Note: Descriptions are shown in the official language in which they were submitted.
6~i~
STEERING AN~ CONTROL SYSTEM FOR PERCUSSION BORING TOOLS
~ACXGROUND OF THE _NVENTION
FIELD OF THE INVENTION
This invention relates generally to percusslon boring
tools, and to the ste~ring and control of percus6ion boring
tools.
DESCRIPTION OF THE PRIOR ART
Utility Companies often find i-t necassary to install
or replace piping beneath diff6rent typ0s of surfaces such as
streets, driveways, railroad tracks, etc. To reduce costs
and public inconvanience by eliminating unnecessary excava-
tion and restoration, utilities sometimes use underground
boring tools to install the new or replacement pipes. Exist-
ing boring tools ara suitable for boring short distances (up
to ~0 ft.), but are not sufficiently advanced to provide dir-
ectional control ~or longer distances. This lack of control,
coupled with the inability of these tools to detect and stser
around obstacles, has limited their use to about 20% of all
excavations, with the majori~y of the remaining sxcavations
being performed by open-cut trenching methods.
Therefore, the development of an economic, guided,
horizontal boring tool would be useful to the utility indust-
ry, since it would significantly increase the use of boring
tools by removing the limitations of poor accuracy and by
reducing the occurrence of damage to in-placa utilities. Use
of such a tool instead of open-cut methods, particularly in
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developed areas, should result in the savings of millions of
dollars annually in rspair, landscape restoration and road
rssurfacing costs.
Conventional pneumatic and hydraullc percussion moles
are de6igned to pierce and compact compressible soils for the
installation of underground utilities without the necessity
of digging large launching and retrieval pits, open cutting
of pavemenk or reclamation of largs areas of land. An inter-
nal striker or hammer reciprocates under the action of com-
pressed air or hydraulic fluid to deliver high energy blowsto ths innar face of the body. These blows propel the tool
through the soil to form an sarthen casing within the soil
that remains open to allow laying of cable or conduit. ~rom
early 1970 to 1972, ~ell Laboratories, in Chester, New Jer-
sey, conducted researoh trying to develop a method of steer-
ing and tracking moles. A 4-inch Schramm Pneumagopher was
fitted with two steerin~ fins and three mutually orthogonal
coils which wers used in conjunction with a surface antenna
to track the position of the tool. One of thes0 fins was
fixed and inclined from the tool's longitudinal a~is while
the other fin was rotatable.
Two boring modes could be obtained with this system
by changing the position of the rotatable fin relative to the
fixsd fin. These were (1) a roll mode in which tha mole was
caused to rotate about its longitudinal center line as it
advanced into the soil and (2) a stesring mode in which the
mole was directed to bore in a curved path.
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The roll mode was used for both straight boring and
as a mean~ for selectively positioning the angular orienta-
tion of the i'ins for subsequ~nt changes in the bore path.
Rotation of the mole was induced by bringing the rotatable
~in into an anti-parallel alignment with the fixed fin. This
positioning r6sults in the gen0ration of a force couple which
initi~t~s and mainta~n3 rotation.
The steering mode was actuat~d by locating the rota-
table fin parallel to the fixed fin. As tha mole penetratss
the 80il, the outer surfaces of the oncoming flns are brought
into contact with the soil and a "slipping wsdga" mschanism
craated. This motion caused the mole to veer in the same
direction as the fins point whan viewed from the back of the
tool.
Published information on the actual field performance
of the prototype appears limited to a pr6sentation by J. T.
Sibilia of Bell Laboratories to the Edison Electric Institute
in Cleveland, Ohio on October 13, 19~2. Sibilia reported
that the system was capable of turning the mole at rates of 1
to 1.5 Per foot of travel. However. the Protot~Pe was never
commerciali~ed.
Sevaral percussion mole steering systems are revealad
in the prior art. Goyne et al, U.S. Patent 3,525,405 dis-
closes a steering system which uses a bevelad planar anvil
that can be continuously rotated or rigidly locked into a
given steering orientation through a clutch assembly. Chepur-
~2~ S~
noi et al, U.S. Patent 3,952,813 discloses an off-axis or
eccentric hammer steering syætem in which the striking posi-
tion of the hammer is controlled by a transmission and motor
asaembly. Gagen et al, U.S. Patent X,794,128 discloses a
steering system employing one fixed and one rotatable tail
fin.
However, in spite of these and other prior art Rys-
tems, the practical realization of a technically and cost-
effeotive steering system has been 81usiV0 because the prior
~ystems require complex parts and extensiva modifications to
existing boring tools, or their staering response has been
far too slow to avoid obstacles or significantly change the
direction of tha boring path within the borehole lengths ty-
pically used.
Several steering systems have been developed in an
attempt to alleviate this problem by providing control of
the boring direction. However, experienoe indicates that the
tool substantially resists sideward movement which seriously
limits the steering response. A method is needed by which20 the tool can travel in a curved path without displacing a
significant amount of soil inside the curve. Reducing this
resistive side force would provide higher steering rates for
the tools. The prior art doas not disclose a steerable per-
cussion boring tool having means for reducing friction during
boring and turning.
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The tools of the prior art have been un3at~sfactory
to the extent that their traverse has not been accurats or
controllable. All too ~requently other underground utilltiea
have been pierced or the ob~ective target has been missed by
a substantial margin. It has also be0n dlfficult to steer
around obstacles and get back on course.
The d$rectional drilling of holes has probably reach-
ad its greatest sophistication in the oil fields. Typical
well surveying equipment utilizes magnetometers, inclinome-
ters and inertial guldance system6 which ar0 complex and
expensive. The wells drilled are substantially vertical.
In respect to utilities, Bell Telephone Laboratories
Incorporated has designad a system for boring horizontal
holes wherein the direction of drilling is controlled by
deploying a three wire antenna system on the surface of the
earth and detecting the position and attitude of the drilling
tool in respect thereto by pickup coils on th0 tool. The
signals detected ar~ then used to develop control signals for
controlling the steering of the tool. Sae, for example,
MacPherson United States Patent No. 5,656,161. Such control
systems have been relatively expensive, and it is no always
easy or convenient to deploy the antenna, for exampls, over a
busy highway.
Steering control is also known in controlling ve-
hicles, aircraft and missiles. In one form of control a
53L
radio beacon is used for guidallce, the aircraft sirnply
f~.llowing a beacon to a runway.
SUMMARY OF Ti~E INVEN'I'ION
Accordingly, -this invention in one aspect seeks to
provide a cost-effective guided horizontal boring tool
which can be used to produce small diameter boreholes into
which utilities, e~g., electri,c or telephone lines, TV
cable, gas distribution piping, or the like, can be
installed.
Further, the present invention seeks to provide a
steering system that offers a repeatable and useful
steering response in boreholes which is compatible with
existing boring equipment and methods and requires only
minimal modification of existing boring tools.
Further, this invention seeks to provide a boring
tool which is constructed to permit transmittal of the
impact force of the tool to the soil while permitting free
rotation of the tool.
Still further, this invention seeks to provide an
improved control system for monitoring and controlling the
direction of a percussion boring tool.
By way of example, the invention in one aspect
pertains to a percussion tool ~or drilling holes in the
soil comprising a cylindrical housing with a front end
shaped for boring, the housing having front and rear
portions of a selected outside continuous constant diameter
and an intermediate portion of lesser outside diameter
providing two spaced continuous circumferential zones of
frictional contact with the soil during boring. A first
B
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means on the front end is provided for applying a boring
Lorce to the soil and a second means in the housing is
provided for applying a percussive force to the boring
force applying means. The front and rear portions are
operable to reduce friction with the wall of the bore
formed by the tool and to permit the tool to turn in its
path along a shorter radius.
Another aspect of the invention for example
; comprehends a controllable percussion tool for drilling
holes in the soil comprising a cylindrical housing with a
tapered front end and a first means on the front end for
applying a boring force to the soil. A second means in the
housing is provided for applying a percussive force to the
boring force applying means, the first and second means
lS being cooperable to apply an asymmetric boring force. A
rotatable sleeve member is supported on the rear end of the
housing and fin means is supported on the rotatable sleeve
member and has a fixed angular position thereon, the sleeve
member and fins comprising a fin assembly. Means are
cooperable with at least one component of the fin assembly
to establish one position permitting the fin assembly to
rotate freely on the housing during movement through the
earth and another position fixed in relation to the housing
to cause the housing to rotate on movement through the
~5 earth. The boring means is operable to bore in a straight
direction when the fin assembly is in the fixed position
and to bore in a curved direction when the fin assembly is
freely rotating.
Further, the invention also comprehends a system
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for boring a bore hole comprising a boring tool having a
longitudinal tool axis and including a motive means for
advancing the tool through the earth and steering means for
directing the motion of the tool relative to the tool axis
in response to control signals. Axial electromagnetic
source means generates an axial alternating magnetic field
directed along an axial source axis and a sensing assembly
is remote from the source means and includes first and
second pickup coils for sensing the alternating magnetic
field. Each coil of the first and second pickup coils is
responsive to the change of magnetic flux linked thereby by
generating respective electrical signals systematically
related thereto, has a respective coil axis, and is rigidly
mounted in respect to the other coil with the coil axis of
the first coil at a substantial angle with respect to the
coil axis of the second coil, the coil axes defining a
sensing assembly axis substantially normal to both the coil
axesO Each coil is also balanced in respect to the sensing
assembly axis to generate a respective null electrical
signal when the lines of magnetic flux at the respective
coil are normal to the respective coil axis at the sensing
assembly axis. One and only one of the source means and
the sensing assembly is rigidly mounted on the tool.
Indicating means responsive to electrical signals generated
by respective first and second pickup coils is provided for
indicating the direction of lines of magnetic flux at the
sensing assembly relative to the sensing assembly axis,
thereby indicating the attitude of the source means
relative to the first and second pickup coils, and control
means provide control signals for controlling the steering
means.
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Othar aspects of tha invsntion w~ ecome apparent
from time to tima throughout tha spacification and clalma as
her01naftar ralatad.
A guided horizontal boring tool constructsd ln ac-
cordance w~th tha pregant invsntion ~111 bensflt utilitiesand rate payars by slgnificantly reducing installation and
maintenance costs of undarground utilitias by reducing the
u88 oI sxpsnaive, open-cut trenching mathods.
The above noted aspects and othar aspects of ths in-
vention are accomplished by an improved steerin~ system forpercusslon boring tools. The steering mechanism compriaes a
slanted-face nose member attached to the anvil of the tool to
produce a turning force on the tool and movabla tail fins in-
corporated into the trailing end of the tool which are ad-
apted to ba selectively positioned relative to tha body ofthe tool to negate ths turning forcs. Turning force may also
ba impartsd to the tool by an eccentric hammsr which delivers
an off-axis impact to the tool anvil. Ths fins also allow the
nosepiece to be orisnted in any givan plane for subsequent
turnlng or dlraction change.
Ths percussion boring tool may optionally have a
cylindrical body with overgage sleeves located over a portion
of the outer body afflxed 90 that they can rotate but cannot
~, - 10 -
~.~S565~
slide axially. The overgage arsas at th0 front and back of
the tool, or altsrnately, an undergage section in the centar
of the tool body permits a 2-point contact (front and rear)
of tha outer housing with the soil wall as opposed to the
line contact which occura without the undercut. The 2-point
contact allows the tool to deviate in an arc without distort-
ing the round cross-sectional profile of th~ pi0rced hole.
Thus, for a givsn steering force at the front and/or back of
the tool, a higher rat0 of turning is possible since a small-
er volum0 of 60il needs to be displaced.
The control system for a percussion boring tool in-
cludes a coil disposed on the tool and energi~ed at relative-
ly low frequency to provide a varying magnetic field extend-
ing axially from the tool and providing lines of magnetic
flux substantially symm0trically disposed about the tool
axis. ~irst and second pickup coils are disposed at a dis-
tance from the tool. These coils have respective axes at a
substantial angle with respect to each other and are mounted
to sense the changing ~lux linked thereby and produce res-
pective first and second elactrical signals.
The coil arrangsment provides respe¢tive null signals
when the respective axes o~ the pickup coils lie substantial-
ly perpandicular to the tool axis and the coils are balanced
about the tool axis. The signals therefore indicate the at-
titude of the tool relative to the coils. A third pickup
coil may be used to sense the range o$ the tool when the
~55i65~
third coil has an axis extending gen~rally toward the tool,
with its output used to normalize the detection signals. The
axe6 of the three coils are prefsrabl~ at an~les of 9O from
each other.
The signals from the respective pickup coils may be
used to determine the attitude of the tool relative to ths
pickup coils, and the information used to control the ~teer-
ing mechanism of he tool. This may be done automatically.
Because this is a null-based system, the control signal may
simply oparate th0 steering mechanism to turn the tool the
reduce tha deviation from null. This caus6s the systam to be
a homing device, like a beacon, and directs the tool along a
path to the coils.
On the other hand, it may be desirable to deviate
from a straight path, as to miss obstacles. The system may
then direct the tool out of the path, around an obstacle, and
back on course.
Thus, an important aspect of the present invention is
to provide a null detection system to determine the attitude
of a horizontal boring tool ralative to detection coils and
for controlling the steering of the tool. Another aspect is
to provide a control system for such a tool wherein the tool
may be steered to home in on the detection coil~.
BRIEF DESCRIPTION OF THE DRA~INGS
Fig. l is a 6chematic view and partial vertical sec-
tion through the earth showing a guided horizontal boring
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5g~S~
tool illustrating the present invention used with a magnetic
attitude ssnsing system.
Figs. 2 and 3 are schematic views, in elevation, of a
fixed/lockable tail fin steering system.
Figs. 4 through 7 are schamatic views, in elevation,
of a movable tail fin system.
Fig. 8 is a schematic Vi9W, in elevation, of a mov-
abl~ fin systarn in combination with an eccentric hammer.
Figs. 9A, 9B, and 9C are segmsnts in longitudinal
cross section of a typical boring tool having a slanted nose
member and fixed/lockabla fin arrangement in the unlocked
position.
Fig. lO is a vertical cross sectional view of the
slanted nose member taken along the line lO - lO of Fig. 9A.
Fig. ll is a longitudinal cross section of the fix-
ed/lockable tail fin assembly of Fig. 9C in the locked po&i-
tion.
Fig. 12 i8 a view, in side elevation, of the fix-
ad/lockable tail fin assembly of Fig. 9C in the locked posi-
tion.
Fig. 13 i8 a partial elevation of the drive teeth
assembly of the fixed/lockable tail fin assembly.
Figs. 14 and 15 are schematic views in ?ongitudinal
cross section showing the operation of a typical percussion
boring tool according to this invention.
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Figs. 16 through 19 are partial longitudinal cro~s
sections of a variation~ of the fixed/lockable fin a6sembly
ln the locked or unlocXed positions.
Figa. 20 and 21 are longitudinal cross sections of an
alternate embodiment of the flxed/lockable fin assembly u8ing
a drive pin arrangement as shown with Figs. 14 and 15,
Fig. 22 is a partial elevation of the dowel pin and
drive tseth of the fixed/lockable tail fin assembly.
Fig~. ~3, 24, 27, 28, 53 and 34 are partial longitu-
dinal cros~ sections of variations of the fixed/lockable finassembly uslng a dowel pl~ and drive teeth driv0, while Fig~.
25 and 26 illu~trate a splined connection, and Figs 29 - 32
show a spline and drive teeth connaction..
Fig. 35 is a longitudinal cross section of a movable
tail fin assembly.
Fig. 36 is a vsrtical cros6 section of the movable
tail fin asaembly of Fig. 38 taken along line 36 - 36 of Fig.
3~.
Figs. 5~ and 38 are partial longitudinal cross sect-
ions of the movable tail fin assembly of Fig. 35 showing theoperati OD .
Fig. 39 is an end Yiew of tha movable tail fin as-
sembly showing the fins in the non-parallel position.
~ igs. 40 and 41 are longitudinal cross sactions of a
portion of a boring tool including an eccentric hammer ar-
rang~ment.
5S6S~
Fig. 42 i8 a schematic view and partial vertical ~ec-
tion through the earth showing a guided horizontal boring
tool illustratlng an alternate embodiment of the percussion
boring tool with overgage sections on the tool housing and
5illustrating the tool as used with a magnetic attitude sens-
ing system
Fig. 43 is a view, in elevation, of a percussion bor-
ing tool having overgage collars, shown in section, secured
in fixad positions at the front and rear of the tool housing.
10Fig. 44 is a view, in elevation, of a peraussion bor-
ing tool having overgage collars, shown in section, one in a
fixad position at the front and the other supported on bear-
ings for rotation at the rear of the tool housing.
Fig. 45 is a view, in elevation, of a percussion bor-
15ing tool having overgage collars, shown in section, secured
in fixed positions at the front and rear of the tool housing
and further showing a slant nosed boring member at the front
and spin controlling fins at the rear.
Fig. 46 is a view, in elevation, of a percussion bor-
20ing tool having overgage collars, shown in section, one in a
fixed position at the front and the other supported on bear-
ings for rotation at tha rear of the tool housing and further
showing a slant nosed boring member at the front and spin
controlling fins at the rear.
25Figs. 47A, 47~, and 47C are segments in longitudinal
cross section of a boring tool as shown in Fig 5 having a
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slanted nosa member and fixed/lockable l'in arrangement in the
unlooked position.
Eig. 4~ is a vertical sectional view, partly dlagram-
matic and partly in perspective, of a horizontal borlng opsr-
ation, showing a horizontal boring tool controlled by a con-
trol system according to the present invention;
Fig. ~9 is a diagrammatic illustration of the sensing
system of he control system of the present invention;
Fig. 50A, 50B, 50C and 50D are diagrammatia illu~-
trations of relationships ol' one sensing coil and the magnet-
ic flux generated by the flux genarator of the sensing system
shown in Fig. 49; and
Fig. ~1 is a diagrammatic illustration of the elec-
trical circuitry of the ssnsing system shown in Fig. 49.
DESCRIPTION OF_THE PREFERRED EMBODIMENTS
Referring to the drawings by numerals of reference,
and particularly to Fig. l, there is ~hown a preferred guid-
ed horizontal boring tool 10 used with a magnetic field atti-
tude sensing system. The boring tool 10 may be used with
various sensing systems, and a magnetic attitude sensing
system is depicted generally as one example. The usual pro-
cedure for using percussion moles is to first loGate and pre-
pare the launching and rstrieval pits. The launching pit P
should be dug slightly deaper than the planned boring depth
and large enough to provide sufficient movement for the oper-
ator. The mole or boring tool 10 is connected to a pneumatic
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~Z556S31
or hydraulic ~ource 11, is than startsd in the soil, stopped
and properly align0d, prefsrably with a sighting frame and
level. The tool is then restarted and boring continued unt$1
the tool axits into th0 retrieval pit (not shown).
Ths boring tool lO may have a pair of coils 12 at the
back end, one of which produces a magnetic field parallel to
the axis of the tool, and the other produces a magnetic field
transverse to the axis of the tool. These coils are inter-
mittently excited by a low frequency ganerator 13. To senRe
the attitude of the tool, two coils 14 and 15 ar0 poaitioned
in the pit P, the axes of which are perpendicular to the de-
Rired path o~ the tool. The line perpendicular to the axes
of these coils at the coil intersection determines the bore-
sit0 axis.
Outputs of th0se Goils can be processed to deYelop
the angle of the tool in both the horizontal and vertical
direotions with respect to the bor0site axis. Using the
transverse field, the same aat of coils can be utilized to
d0termine th0 angular rotation of th0 tool to provid0 suffi-
~cient control for certain types of steering systems. For
th0se systems, the angular rotation of the tool is displayed
along with the plane in which the tool is expected to steer
upon actuation o~ the guidance control system.
The mechanical guidance of ths tool ¢an also be con-
trolled at a display panel 16. From controls located at dis-
play pan01 16, both the operation oi~ the tool lO and the
~2~5~
pneumatic or hydraulic actuation of the fins lr ¢an be ac-
complished as descrlbed hereinafter.
As shown in ~ig. 1, the boring tool 10 includes a
steering system with a slanted-face nose member 18 attach0d
to the anvil 33 of the tool to produce a turning force on the
tool and tail fins 17 on a rotary housing 19 on the trailing
end of the tool adapted to be ~alectively posltioned relative
to the body of the tool to negate the turning force. Turning
force may also be imparted to the tool by an internal 0ccent-
ri¢ hammer (~ig. 41) described hereinafter which delivars an
off-axis impact to the tool anvil.
For turning the tool, the tail fins 17 are movad into
a position where they may spin about tha longitudinal axis of
the tool lO and the slanted nose member 18 or eccentric ham-
mer will deflect the tool in a given direction. When the
fins 17 are moved to a poaition causing the tool lO to rotat0
about its longltudinal axis, the rotation will negste the
turning effect of the nose member 18 or accentrlc hammer as
well as provide a means for or~enting the nose piece into any
given plane for subsequent turning or direction change. It
should be understood that either an eccentric hammer or anvil
will produce the desired turning force, since the only re-
quirament is that tha axis of the impact does not pass
through the frontal center of pressure.
The steering system of the present invention will
allow the operator to avoid damaging other underground serv-
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~Z55~
ices ~such as power cables) or to a~oid placing underground
utilitie~ where they may be damaged.
Figs. 2 through 7 illustrate various combinations and
implementations of the combination ~lanted nose member and
tail fins stearing system schematically and lllustrates the
basic operation of each design. The function of the tail fins
i8 to pro~id0 a method of executing controlled changes to ths
boring direction.
A fix0d/lockable tail fin stearing system 17 i8 il-
10 lustated in Figs 2 and 3. To turn the tool 10, the tool isallowed to rotate about th~ longitudinal axis due to the
turning force of the tail finq when in the lock~d po~itio~
until khe proper tool fac0 orlentation is obtained (~ig. 2).
The housing 19 is then unlocked and spins freely, whereby the
15 tool moves in a curved path by the turning force of the
slanted faoe nose member 18. Straight boring by the tool 10
is accomplished by locking tall fin housing 19 to the main
body 20 of the tool 10 (Fig, 3), to rotate the tool body and
thus negate the turning action of the slanted nose member 18.
A boring tool 21 having a movable tail fin system is
illustrated in Figs. 4 - 7. To turn or change direction of
the tool 21, the tail fins 22 are activated to a parallel
position relative to the longitudinal axis of the tool body
20 and the tool 21 i~ allowed to turn relative to the longi-
25 tudinal axis due to the turning force of the nose member 18
or the eccentric hammer. Proper tool face orientation is
-- 19 --
~2~ 6.~3L
obtained (Figs. ~ and 5) by usa of the tail fins in a ske~ed
inclined position. Straight boring of the tool is accom-
plished by activating the fins 22 to an inclined position
r01ative to ths mols axis (Figs. 6 and 7) to rotate tha tool
body and thus negate thH turning aation o~ ths slanted ~ose
member 18.
~ ig. 8 illustratea a boring tool 23 with a movable
tail fln system in combination with an eccentric hammer 24.
It should bs understood that the eccentric hammer may be u~ed
in combination with either the fixed/lockabla fin system or
tho ~o~able fin systHm ~nd with or without the slanted nose
member, depending upon the ~articular application. Either an
eccentric hammer or anvil will produce the desired result,
since the only requirement is that the axis of the impact
does not pass through the frontal center of pr3ssure. Unless
nsgated by one of the previously described fin systems, the
eocentric hammer 24 provides the side force rsquired to turn
the tool.
The eccentric hammer 24 is keyed to the main body 2B
of the tool 23 by a pin 26 or other suitable means to main-
tain the larger mass of the hammer on one sids of the longi-
tudinal axis of the tool. Turning of the tool 23 i6 accom-
p1ished by unlocking the tail fin housing of the fixed/lock-
able embodiment from the main mole body or turning the fins
of the movable fin embodiment to a position parallsl to ths
body axis. The parallel fins or unlocked housing position
- 20 -
~25~
cli~inates the fins ability to negate the eccentric hammer
force. To steer the tool 23, th0 tail fin housing is unlock-
sd or the fins are activated to a skewad inclined poRition
relative to the tool body axis and the tool iB turned by the
eccentric hammer force until the proper tool face ori0ntation
i 8 obtained.
Straight boring is accomplished in all of the previ-
ously described impl0mentations by continuously rotating the
tool. This distributes the turnin~ force over 360 and caus-
es tha tool to bore a helioal (nearly straight) hole.
~ igs. 9A, 9~, 9C, and lO illustrate a typical boringtool 27 having a slanted nose member and fixed/lockable iin
arrangement as described generally in reference to Figs. l
and 2. As shown, the boring tool lO comprises an elongated
hollow cylindrical outer housing or body 28. The outer front
end of th~ body 28 tapers inwardly forming a conical portion
29. The internal diameter of the body 28 tapers inwardly
near the front end forming a conical surface 50 which termin-
ates in a reduced diameter 31 extending longitudinally inward
from the front end. The rear end of the body 28 has internal
threads 32 for raceiving a tail fin assembly (sae ~ig. 9C).
An anvil 33 having a conical back portion 34 and an
elongated cylindrical front portion 3~ is positionsd in the
front end of body 28. The conical back portion 34 of anvil
33 forms an interference fit on the conical surface 30 of the
body 28, and the elongated cylindrical portion 35 extends
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~25~S~
outwardly a predetermined distance beyond the front end of
the body. A flat transverse surface 56 at the back end of
anvil 33 reGeives the impact of a reciprocating hammer 37.
R~ciprocating hammsr 37 is an elongated cylindrical
member sl$dably received within the cylindrical recass 38 oi'
the body 28. A substantial portion of the outer diameter of
the hammer 28 is smaller in diameter than the recess 38 of
the body 28, forming an annular cavity 39 therebetween. A
relatively shorter portion 40 at the back end of the hammer
37 is of larger diameter to provide a sliding fit against the
interior wall of recess 38 of the body 28.
A cantral cavity 41 extends longitudinally inward a
distance from the back end of the hammer 37. A cylindrical
bushing 42 is slidably disposed within the hammer cavity 41,
the oircumference of which provides a 61iding fit against the
inner surface of the central cavity 41. The front surface 45
of the front end of the hammer 37 is shaped to provide an im-
pact centrally on the flat surface 36 of the anvil 33. As
described hereinafter, the hammer configuratlon may also be
adapted to d0liver an eccentric impact force on the anvil.
Air passages 44 in the sidewall of hammer 37 inwardly
ad~acent the shorter rear portion 40 communicate the central
cavity 41 with the annular cavity 39. An air distribution
tubs 45 extends centrally through the bushing 42 and has a
back and 46 extending outwardly of the body 28 connected by
~ittings 47 to a flexible hose 48. For reciprocating the
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~2~65~
hammer 37, the air distribution tube 45 is in permanent com-
munication with a compressed air source 11 (Fig. lj. The
arrangsment of the passages ~ and the bushlng 42 i8 sueh
that, during reciprocation of the hammer 3q, the air distri-
bution tube ~5 alternately communicates via the passage3 44,the annular cavity 39 with either the c0ntral cavity 41 or
atmosphere at regular intervals.
A cylindrical stop member 49 is secured within the
recess 38 in the body 28 near the back end and has a serie6
of longitudinally-extending, circumferentially-spaced pass-
ageways 50 for exhausting the interlor of the body 28 to at-
mosphere and a central passage through which tha air distri-
bution tubs 45 extends.
A slant-end nose member 18 has a cylindrically re-
cessed portion 52 with a central cylindrical bore 53 th0rein
which is received on the cylindrical portion 35 of the anvil
33 (Figs. ~A and 10). A slot 54 through the sidewall of the
cylindrical portion 18 extends longitudinally sub6tantially
the length of the central bore 53 and a transvsrse slot ex-
tends radially from the bore 53 to the outer circumference of
the cylindrical portion, providing flexibility to the cylin-
drical portion for clamping the nose rnember to the anvil. A
flat 56 is provided on one side of cylindrical portion 18 and
longitudinally spaced holes 5q are drilled therethrough in
alignment with threaded bores 58 on the other side. Screws
- 23 -
-
6S~
59 ar0 received in the holes 57 and bores 58 and tightened to
6ecure the nose membar 18 to the anvil 33.
The sidewall of the nosa membar 18 extends forward
from the cylindrical portion 52 and one sid3 iB milled to
form a flat inclined surface 60 which tapers to a polnt at
the extended end. The length and degree of inclination may
vary depending upon the particular application. The nose
member 18 may optionally have a flat rectangular ~in 61
(shown in dotted line) se¢urad to the sidewall of th0 cylin-
driaal portion 52 to extend substantially the length thereofand radially outward therefrom in a radially opposed position
to the inclin0d surfaca 60.
Slanted nose members 18 of 2-1/2" and 3-1/2" dia-
meter with an~les from 10 to 40 (as indicated b~ an~le "A")
have been tested and show the nosa member to be highly ef-
fective in turning the tool with a minimum turning radius of
28 feet b~ing achieved with a 3-1/2 inch 15 degree nose mem-
ber. Testing also demonstrated that the turning effect of
the nose member was highly repeatable with deviations among
tests of any nose membar seldom varying by more than a few
inches in 35 feet of bore. Additionally, the slanted nose
members w~re shown to have no adverse effect on penetration
rate and in some cases, actually increased it.
It has also been found that the turning radius varies
linearly with the angle of inclination. ~or a given nose
- 24 -
~l~5~
angle, the turning radius wSll decrease in direct proportion
to an increase in area.
A tail fin asssmbly 19 is secured in the back end of
the body 28 (Fig. 9C). A fixed/lockable tail fin assembly 19
is illustrated in the example and othsr variations ~ill be
de6crib~d hereinaft~r. The tail fin assembly 10 comprisss a
cylindrical connecting sub 63 having external threads 64 at
the front end which are received within the intarnal threads
32 at the back end of the body 28. Sub 63 has a short re-
duced outside dlameter portion 65 forming shoulder 66 there-
between and a second reduced diameter 67 ad~acent the short
portion 65 forms a second shoulder 68.
An O-ring seal 69 is located on the reduced diameter
65 intermediate the shoulders 66 and 68. The rear portion 70
of the sub 63 is smaller in diameter than the second reduced
diameter 67 forming a third shoulder 71 therabetween and
provided with a circumferentlal O-ring seal 72 and an intern-
al 0-ring seal 73. Internal threads 74 are provided in the
rear portion 70 inwardly of the seal 73. A circumferential
bu~hing 75 of suitable bearing material such as bronze is
provided on the second reduced diameter 67.
A series of longitudinal circumferentially spaced
grooYes or keyways 76 are formed on the circumference of the
r~ar portion 70 of the sub 63. A hollow cylindrical piston
77 is slidably received on the circumference of the rear por-
- 25 -
~2~;S6~
tion 70. A series of longitudinal circumferentially spacsd
grooves or kayways ~8 are formed on the interior surface at
the front portion of the piaton 77 in opposed relation to ths
6ub keyways 76. A series of keys or dowel pin6 79 ars rs-
ceived within the k~yways 76 and 78 to prevent rotary motionbstween the su.b 63 and ths piston 77.
first internal cavity 80 sxtends inwardly from the
~eyway ~8 terminating in a short reduced diam~ter portion 81
which forms a ahoulder 8~ therebetwssn. A second cavity 83
extends lnwardly from the back end 84 of the piston ~ term-
inating at the reducod diametar portlon 81. An internal ann-
ular 0-ring seal 85 is provided on the reduced diameter por-
tion 81. A~ shown in Figs. 9C and 13, a series of drive
teeth 86 are formed on the back end of the piston 77. The
t0eth 86 comprise a series of circumferentlally 6paced raised
surfac0s ~7 having a straight side 88 and an angularly slop-
ing side 89 forming a one-way ratchet configuration. A com-
presaion spring 90 is received within the first cavity 80 of
the piston 77 and is compr6ssed between the back end ~0 of
the sub 63 and the shoulder 82 of th6 piston 77 to urga ths
pi~ton outwardly from the sub.
An elongated, hollow cylindrical rotating fin sleeve
91 is slidably and rotatably recsived on the out~r periphery
of sub 63. Ths fin slesva 91 has a csntral longitudinal bore
92 and a ghort countsrbore 93 of larger diameter extending
inwardly from the front end and defining an annular shouldar
- 26 -
~L~5i5~
94 therebetween. The counterbore 93 fits over the short re-
duced diameter 65 o~ the sub 63 with the 0-ring 69 providing
a rotary seal therebetween. A flat annular bushing 95 of
suitable bearlng matsrial such as bronze is disposed between
tha shoulders 6~ and 94 to reduce ~riction therebstween. A
sacond counterbore 06 extends inwardly from the back end of
th~ fin sleave 91.
A hollow cylindrical slesve 9~ is secured within t~e
kecond countarbore 96 by suitable means such as walding. The
sleeeve 97 has a central bora 08 substantially the same dia-
meter as the second cavity 83 of the piston ~7 and a counter-
bore 99 extending inwardly from the back end defining should-
er 100 therebetween. As shown in Figs. 9C and 13, a series
of drive teeth 101 are formed on the front end of the sleeve
9r. The teeth 101 comprise a series of circumferentially
spaced raised surfaces 102 having a straight side 103 and an
angularly sloping side 104 forming a one-way ratchet config-
uration. The teeth correspond in opposed relationship to the
teeth 86 of the piston 77 for operative engagement therewith.
A seriss of flat radially and angularly oppossd fins
105 are secured to the exterior of the fin sleeve 91 to ex-
tend radially outward ther~from. (Figs. 9C, 11 and 121 The
fins 105 ars secured at opposing angles relative to the lon-
gitudinal axis of the sleevs 91 to impart a rotational force
on the sleeve.
- 2~ -
~SG~l
An elongatsd hollow cap ~laeve 106 having external
threads 107 at the front end i6 slidably received within the
sliding piston 77 and the sleeve 97 and threadedly secured in
the internal threads 74 at the rear portion 70 of the sub 63.
The cap sleeve 106 axtends rsarwardly from the threads 107
and an enlarged diameter portion 108 forms a first shoulder
109 spaced from the threaded portion and a 6econd enlargsd
diametsr 110 forms a second shoulder 111 spaced from the
first 6houlder.
An 0-ring seal 112 is provided on the enlarged dia-
meter 108 near the shouldHr 109 and a second 0-ring seal 113
is providsd on the second enlarged diameter 110 near the
second ahoulder 111. The 0-ring 112 forms a reciprocating
seal on the interior of the second cavity 83 of the piston 77
and the 0-ring 113 forms a rotary seal on the counterbore 99
of the sleeve 97. The 0-ring 85 in the piston 77 forms a
reciprocating seal on the extended sidewall of the cap 106.
An annular chamber 114 is formed between the ext0rior
of the sidewall of the cap 106 and the second counterbore 83
20 which is sealed at each end by the 0-rings 85 and 112. A
circumferential bushing 115 i6 provided on the first enlargad
diameter 108 and an annular bushing 116 on the second enlarg-
sd diameter 110 is captured between the shoulders 100 and 111
to reduce friction between ~he sleeve 97 and the oap 106. The
rear portion of the cap 106 has small bores 117 arranged to
receive a spannsr wrench for effecting the threaded connect-
- 28 -
~25~
ion. A threaded bore 118 at the back end of the cap 106
recslves a hose fitting (not shown) and a small passageway
119 extends inwardly from the threaded bore 118 to communi-
cate the annular chamber 114 with a fluid or air aource (not
shown). A flexible hose extends outwardly of the cap 106 and
i9 connected to the fluid or air source for effecting recip-
rocation of the piston 77. A second small paRsage~ay 120
communicates th~ first cavity 80 with atmosphere to relieve
pressure which might othsrwi6e become trapped therein. Pa6s-
age 120 may also be usad for application of pressure to theforward end of the plston 77 for rsturn movem0nt.
OPERATION
Having thus described the ma~or components of tha
boring tool assembly, an explanation of the opsration of a
typical boring tool and the tail fin assembly follows.
The operation of the percussion boring tool 27 is il-
lustrated schematically in Figs. 14 and 15. Under action of
compressed alr or hydraulic fluid in the central cavity 41,
the hammer 37 moves toward the front of ths body 28. At the
foremost position, the hammer imparts an impact on the flat
surface 36 of the anvil 33.
In this position (Fig. 14), compressed air is admit-
ted through the passagas 44 from ths cantral cavity 41 into
the annular cavity 39. Since the effective area of the ham-
mer including the larger diametar rsar portion 40 is grsaterthan the affactive area of the central cavity 41, the hammer
- 29 -
~zss~
starts moving in the opposite direction. During this move-
ment, the bushing 42 closes ths passages 44 (~ig. 15), thera-
by interrupting the admission of compressed air into annular
cavity 41.
The hammer 37 continues its movemant by ths e~pansion
of the the air in the annular cavity 39 until the passagss 44
ara displaced beyond the end~ of the bushing 42, and the an-
nular cavity axhausts to atmosphere through the holes 50 in
the stop member 49. In this position, tha air i8 exhausted
from tha annular cavity 39 through the passages 44 now above
the trailing edge of the bushing 42 and the holes 50 ln the
stop member 49. Then the cycle is repeated.
The operation of the tail fin assembly 62 is best
seen with reference to Figs. 9C and 11. The compressed air
or fluid in the annular cavity 114 moves the plston 77 again-
st the force of the spring 9O and toward the front of the sub
63. In the foramost position, the front end of tha piston ~7
contacts the shoulder 71 and the drivs teeth 86 and 101 be-
come dis-engaged. In this position (Fig. 9C), compressed air
or fluid is admitted through the passage 119 from the source
into the annular chamber 114. The fin sleave 91 is than free
to rotate relative to tha tool body.
When the air or fluid pressure within the chamber 114
is relieved, ths force of the spring 9O movas the piston 77
in the opposite dirsction (Fig. 11). During this movement,
- 30 -
~2S~
the drive teath 86 and 101 become engaged once again and the
fln sleave 91 b0comes locked against rotational movement rel-
ativs to the tool body. Pressure which may otherwise become
trapped in the first cavity 80 and hindar reciprocation i8
exhausted through the pressure reliaf passage 120 to atmos-
phere. The cycle may be selectively repeated as nece6sary
for propar alignment tha slanted nose member 18 and attitude
ad~ustment of the tool. It should be understood that the
passaga 120 may also be connected to a fluid, i.e. liquid or
air, source for moving tha pi6ton to the raarward position.
ANOTHER EM~ODIMENT
Another embodiment of the tail fin assembly clutch
mechanism is illustrated in Figs. 16 and 17. Some parts are
given the same numerals of reference to avoid repetition.
The tail fin assembly 119 comprises a cylindrical connecting
sub 163 having extarnal threads 164 at the front end which
are received within th0 internal threads 32 at the back end
oi the body 2~. Sub 163 has a short reduced outside diamster
portion 165 forming a shoulder 166. The raar portion 170 of
the sub 163 is smaller in diameter than the reduced diameter
165 forming ~ third shoulder 171 therebetwesn and provided
with a circumferential O-ring sea1 172.
A series of longitudinal circumfarentially-spaced
grooves or keyways 176 are formed on the rear portion 170 of
the sub 163. A hollow cyllndrical piston 1~7 is ~lidably
- 31 -
r3ceived on the circumference of the rear portion 170. A
series of longitudinal circumferentially spaced groovss or
Xeyways 178 ara formed on the lnterior surface at the front
portion of ths piston 177 in oppossd rslation to the sub
keyways 176. A ssries of k3ys or dowel pins 179 are recsSved
within the Xeyways 176 and 178 to prevent rotary motion be-
tween the sub 163 and the piston 177.
A first internal oavity 180 extends inwardly from th3
keyway 178 terminating in a short reduced diameter portion
10 181 which forms a shoulder 182 therebetween. A second cavity
183 smaller than ths first extends inwardly from the bacX end
184 of the piston 77 terminating at the reduaed diameter por-
tion 181. O-rlng seals 173 and 18~ ars provided on the inter-
ior of the first aavity 180 and reduced diamster portion 181
respectively. As previously shown and d3scribed with refer-
ence to Fig. 13, a series of drive teeth 86 are formed on the
back end of the piston 177. Th3 teeth 86 comprise a ssries
of circumferentially spaced raised surfaces 87 having a
straight side 88 and an angularly sloping side 8a forming a
one-way ratchet configuration.
An slongated hollow cylindrical rotating fin sleeve
91 i8 rotatably r3ceived on the outer periphsry of th3 sub
163. Th3 fin sleeve 191 has a central longitudinal bore 192.
The bore 192 is rotatably received on the reduced diamster
25 165 of the sub 163 with the O-ring 169 providing a rotary
- 32 -
6S~L
seal therebetween. A flat annular bushing 195 of suitable
materi~l such as bronze is disposed between the shoulder 1~8
and tha front of the fin sl0eve 191 to reduce friction.
A hollow cylindrical sl0eve 197 i8 secured within the
rear portion of the fin sleeve bore 192 by suitable means
such a~ welding. The slaeeve 197 has a central bore 198 sub-
stantially the same diam0ter as the second cavity 183 of the
piston 177. As previously shown and described with reference
to Fig. 13, a series of drive taeth 101 are ~ormed on the
front end of the sleeve 197. The teeth 101 comprise a serie
of circumferantially spacad raised surfaces 102 having a
straight side 103 and an angularly sloping sid3 104 forming a
one-way ratchet configuration. Tha teeth correspond in opp-
osed relationship to the teeth 86 of the piston 177 for oper-
15 ative engagement therewith. An 0-ring 213 and a bushing 215
are provided in the central bore 198.
A series of ~lat, radially and angularly opposed fins
205 are secured to the e~terior of the fin sleeve 191 to ex-
tend radially outward therefrom. The fins 205 are secured at
20 opposing angles relative to the longitudinal axis of the
sleeve 191 to impart a rotational force on the sleeve.
An elongated hollow cylindrical cylinder cap 206
having external threads 207 at the front end is slidably re-
ceived ~ithin tha sliding piston 177 and the sleeve 197 and
25 threadedly secured in the internal threads 174 at tha rear
- 33 -
6~
portion 1~0 of the Rub 163. The circumference of the cap 206
extends rearwardly from the threads 20~ and an enlarged dia-
meter portion 208 forms first shoulder 20~ spaced from the
threaded portion and a seaond enl~rged diamcter 210 forms sa-
cond ~houldar 211 spaced from the first shoulder. An 0-ring
seal 212 is provided on the enlarged diameter 208 near the
shoulder 209. The 0-ring 212 forms a reciprocating seal on
the interior of the se¢ond cavity 183 of the piston 177 and
tha 0-ring 213 forms a rotary seal on the central bore 198 of
the sleev~ 197. The 0-ring 185 ln the piston 177 forms a
reciprocating seal on the extended sidewall of the cap 206.
An annular rear chamber 214 is formed between the
exterior of the sidewall of the cap 206 and the second small-
er bore 183 which is sealed at each end by the 0-rings 185
and 212. An annular front chamber 216 is formed between the
sidewall of the cap 206, the cavity 180, and the back end of
the sub 163, which is sealed by the 0-rings lq2, 1~3, and
18~. The side wall of the sub 163 has small bores 21~ ar-
ranged to receive a suitable wrench for effecting the ~hread-
ed conneotion. A threaded bore 218 at the back end of thecap 206 receives a hose fitt$ng (not shown) and a small pass-
ageway 219 extend6 inwardly from the threaded bore 218 to
communicate the rear chamber 214 with a fluid or air sourc~
(not shown). Another similar threaded bore at the back ~nd
- 34 -
~2~
of the ¢ap receives a ho~e fltting (not shown) and a small
passageway 220 extends inwardly from the threaded bore to
communicate the front chamber 216 with a fluid or air source
lnot shown). Flexible hoses extend outwardly of the cap ~06
and are connected to the fluid or air source for 0ffecting
reciprocation of the piston 177.
The operation of the tail fin assembly 119 i8 illus-
trated schematically in Figs. 16 and 17. Under action of
compressed air or fluid in the r0ar chamber 214, the piston
177 movas toward the front of the sub 163. When in its fore-
most position, the drive teeth 86 and 101 are disengaged and
the fin sleevs 191 is free to rotate about the longitudinal
axis of thc tool body. In this position (Fig. 16), compress-
ed air or fluid in the front chambcr 216 has been exhausted.
To lock the tail fins against rotational movement, compressed
air or fluid is admitted through the passage 220 into the
front chamber 216 and exhausted from the rear chamber 214 to
move the piston 177 in the oppo~ite direction. In this posi-
tion (Fig. 17), tha drive teeth 86 and 101 are once again
engaged preventing rotational movement. The cycle may be
selectively repeated as necessary for proper alignment the
slanted nose member and attitude adjustment of the tool.
A FURTHER EMBODIMENT
Another variation of the flxed/lockable tail ~in as-
sembly having drive tecth is illustrated ~n Figs. 18 and 19.
- 35 -
~2~S~
To avoid r~petition, some of tha components, detail6, and
reference num~rals pr0viou61y 6hown and de6cribsd with r0~-
erence to Flgs. 9C and 11 will not be repeated here. Other
component~ previously describsd will carry the same numerals
of reference.
The tail fin assembly 210 comprise~ a cylindrical
connacting sub 263 having external threads at the front and
which are r~ceived within ths internal thraads at the back
end of the body. The sub 263 has a short reduced diameter
portion forming a first shoulder and a second reducad dia-
m0ter ad;acent the short portion forms a s0cond shoulder. An
annular O-ring seal is provided on th0 first reduced diameter
intermediate the first and second shoulders. The sidewall of
the sub 263 extends rearwardly from the 6econd shoulder. The
rear portion 270 of the sub 263 is smaller in diam0ter than
the second reduced diameter forming a third 6houlder 268 and
a fourth reduced diam~ter defines a fourth shoulder 271. A
circumferential O-ring seal 272 i8 provided at back end of
the sub 263. External threads 274 are provided in the rsar
portion 270 inwardly of the seal 272.
A series of circumferentially spaced spherical aper-
tures 276 are formed on the circumference of the sidewall of
the sub 263 n0ar ths third shoulder 271 and carry a series of
balls 279. A hollow cylindri~cal piston 277 is slidably re-
ceived on the circumference of the raar portion 270. A ser-
- 36 -
~z~s~
ieB of longitudinal circumferentially 6paced groovss or key-
ways 278 are formed on the int0rior ~urface at the front por-
tion of the piston 277 in oppossd relation to the balls 279.
The balls 279 within apertur~s 276 and keyways 278 prevsnt
rotary motion betwaan ~ub 263 and pi~ton 277.
A first cavity 280 extends inwardly from the front
end of th3 piaton 27r and terminates in a short reduced dia-
meter portion 281 which forms a 6houlder 282. A sacond cav-
ity 283 axtends inwardly from tha back end of th~ piston 2~7
terminating at the reducad diameter portion 281. An 0-ring
seal 285 is provided on the reduced diamster portion 281. As
shown in Fig. 13, a 6~ri0s of drivs teeth 86 ara formed on
the back end of the piston 277. The teeth 86 comprise a ~er-
ies of circumferantially spaced raised surfaces 87 having a
straight side 88 and an angularly sloping side 89 forming a
one-way ratchet configuration. A compression spring 290
surrounds the sidewall o~ the sub 263 and the ends of the
spring are biased against the shoulder 268 of the sub 270 and
the front end of the piston 277 to urge the piston outwardly
from the sub.
As previously describ~d a hollow cylindrical rotating
fin 61eeve 291 having a rear counterbore 296 is slldably and
rotatably received on tha outer periphery of sub 263. A hol-
low cylindrical sleeve 297 i8 secured within the 6scond coun-
terbora 296 by suitable means such a6 wslding. The slaevs
- 37 -
~z5S~
297 has a central bor0 substantially the 6ame diameter as the
second cavity 283 of the piston 277 As shown in Fig. 13, a
saries of drive teeth 101 are formad on the front 3nd o~ the
sleeve 297. The teeth 101 comprise a series of circumferen-
tially ~paced raised surfaces 102 having a straight side 103
and an angularly sloping sida 104 forM1ng a one-way ratchet
configuration. The teeth correspond in opposed relation6hip
to the te~th 86 of the pi~ton 277 for operative engagement
therewith. A s~ries o~ flat radially and angularly opposed
fins as previously described are s0cured to the exterior of
the fin sle0ve to extend radially outward therefrom.
An elongated hollow cylindrical cylinder cap 306
having internal threads 307 at the front end is slidably re-
ceived within the ~liding piston 277 and the sleeve 297 and
threadedly secured on tha external threads 274 at the rear
portion 270 of tha sub 263. An 0-ring seal 312 is provided
on the outer front portion of cap 306 and a second 0-ring
seal 313 is provided on the rear portion. The 0-ring 312
forms a reciprocating seal on the interior of cavity 283 of
piston 277 and 0-ring 313 forms a rotary saal on ths count-
erbore of fin sleeve 291. Tha 0-ring 285 in piston 27~ forms
a reciprocating seal on the ~ldewall of cap 306.
An annular chamber 314 is formed between the exterior
of the sidewall of the cap 306 and the countarbore 283 which
i~ sealad at each end by the 0-rings 285 and 312. Bushings
- 38 -
~55~
as previou~ly described sre provid0d on the sub 263 and cyl-
inder cap 306 to reduce friction therebeween. Tha rear por-
tion of the cap has a threaded bore 318 at the bacX end of
the cap 306 which receives a hose fitting (not shown) and a
small passageway 319 e~tends inwardly from the threadsd bore
318 to communicate the annular chamb0r 314 with a fluid or
air source (not shown). A flexible hose ext3nds out~ardly of
the cap 306 and is connscted to the fluid or air sourcs for
effscting reciprocation of the piston 277.
The operation of the tail fin assembly 219 is best
seen with reference to Figs. 18 and 19. Compressed air or
fluid in the annular cavity 314 moves the piston 277 to over-
come th0 force of the spring 290 and move toward the front of
sub 263. In the foremost position, the driv0 teeth 86 and
lOl b0come disangaged. In this position (Fig. 18), comprass-
ed air or fluid is admitted through the passage 319 from the
source into the annular chamber 314. The fin sleeve 291 is
then free to rotate relative to the tool body.
When the air or fluid pressure within the chamber 314
is relieved, the force of the spring 290 moves tha piston 277
in the opposite diraction (Fig. 19). During this movement,
th0 drive t0eth 86 and 101 become engaged once again and the
fin sleeve 291 becomes locked against rotational movement
relative to the tool body. The cycle may be selectively
repeated as necessary for proper operation of the tool.
- 39 -
~s~s~
STILL ANOTHER EMBODIMENT
~ igs. 20 and 21 are longitudinal cross sections of an
altarnata embodimant of the fixed/lockable fin assembly which
incorporates a driv0 pin arrangement in place of ons of the
drive taeth membsrs previously described. It will be noted
that tha drive pin arrangement nacassitates moving the ~in
sleeve along the longitudinal axis to effect fin positionlng.
The tail fln asAembly 400 compris0s a cylindrical
connecting sub 401 having external threads 402 at the front
end which are received within the intarnal threads 32 at tha
rear portion of th0 body 28. The sub 401 has a first reduced
diameter portion 403 forming a first shoulder 404 and a se-
cond reduced diameter 405 adjacent the first forms a second
shoulder 406 which receives an annular seal 407. The rear
15 portion 408 of sub 401 is smaller in diameter than tha second
reduced diameter 406 and extends longitudinally therefrom.
A thin cylindrical retainer ring 409 i~ secursd on
the first reduced diametsr 403 of thc sub 401 by screws 410
and a small annular rib 411 on the interior surface of the
20 ring captures the seal 407 within the second shoulder 406.
The rear and of ring 409 ext~nds a short distance beyond seal
407 to surround the forward and of the rear portion 408 of
the sub 401.
An elongated, hollow cylindrical rotating fin sleeve
25 412 is slidably and rotatably received within the extended
- 40 -
~z~s~
portion of ring 409 and surround6 the r0ar portion 408 of sub
401. The fin sleeve 412 ha~ a central longitudinal bore 413
and a counterbora 41~ of larger diameter extending inwardly
from the back end and defining an annular shoulder 415 ther0-
between. An 0-ring seal 416 on fin sls0ve 412 provides a
rotary and reciprocating seal on the inner surface of ring
40~. A plurality of circumferentially spaced dowel pins 417
extend radially inwardly through the side wall of the fin
sleeve 412 and terminate a short dlstance from th0 clrcumfer-
enc0 o~ ~he r0ar portion 408 of the sub 401. An annular 0-
ring seal 418 and a bushing 419 is provided on the interior
surface of the fin sleeve 412 intermediate thfl dowel pins 41
and shoulder 415.
A series of radially and angularly opposad fins 420
ar~ secur~d to the exterior of the rotating fin sleeve 412 to
~xtend radlally outward therefrom. The fins are secured at
opposing angles relative to the longitudinal axis of the
sleeve 412 to impart a rotational force on the 61eev~. An
elongated hollow cylindrical cap 421 is slidably received on
the sub rear portion 408 within fin sleeve 412 and secured to
sub 401 by means of a screw 422 at the rear portion theraof.
The cap 421 has a r0duced diamstcr front portion 423 and an
enlarged diameter r0ar portion 424 forming a shoulder 425. A
pair of longitudinally spac~d 0-rings 426 are positioned on
the rcar portion 424 and a bushing 427 is provid0d intermedi-
~zss~
ate the O-rings 426. The enlarged diameter rear portion 424
o~ the cap 421 is rotatably received within counterbore 414
with the O-rings 426 providing a rotary æeal therebetwaen.
As shown in ~igs. 20, 21, and 22, a series of drive
teeth 428 are formed on the front end o~ the cap 421. The
drlve teeth 428 comprise a series o~ circumferentially ~paced
raised surfaces ~29, each having a gsnerally stralght Ride
430 and an angularly sloping sid~ 431 forming a one-way rat-
chet conriguratlon. The spacing o~ th0 driv0 teeth 428 rela-
tiv0 to the dowel pins 41~ i8 BUCh that the pins will be
r~tained by the teeth in the locked position to prevent rot-
ary motion between the fin slesve 412 and cap 421 as describ-
ed h~reinafter.
Whsn properly po~ition0d, an annular chamber 432 is
formed betwean ths should0r 415 of the ~in sleev~ and the
should0r 425 of the cap and sealed at each end by the O-r~ngs
418 and 426. A thr0aded bore g33 at the back end of the cap
421 receives a hose fitting (not shown) and a small passags-
way 434 extends inwardly from the threaded bore to communi-
cate the annular chamber 432 with a fluid or air source (not
shown) for reciprocatiing fin sleev0 412.
The operation of the tail fin assembly with dowel
pins is best seen with refarence to Figs. 20, 21, and 22.
Compressed alr or fluid ln the annular chamber 432 moves the
fin ~leevs 412 toward the front o~ the sub 401. In the fore-
- 42 -
-
~`ss~s~
most position, the front snd of th0 61eeve 412 contact6 ths
seal 40~ and the dowel pins 417 disengage from the drive
teeth 428. In this position (Fig. 20), comprassed air or
fluid is admitted through the passage 434 from the source
into the annular chamber 432. Ths fin sleeve 412 is then
fre0 to rotate relative to the tool body.
When th0 air or fluid pressure within the chamber 432
is relieved, the driving force of the tool hammer carries the
tool including the cap 421 forward (Fig. 21). During this
movement, drlve t0sth 428 and dowel pins 417 become engaged
once again and fin sleeve 412 becomes locked against rotat-
ional movement relative to tha tool body. The cycle may be
~electively r0peated as necessary for proper alignment of the
~lanted nos0 member and attitude ad~ustment of the tool.
A ~URTHER ~MBODIMENT
~igs. 23 and 24 are partial longitudinal cross sect-
ions of variations of the fi~ed/lockable fin a6sembly using a
drive pin. The tail fin assembly 500 comprises a cylindrical
connecting sub 501 having external threads 502 at the front
end which are received within the internal threads 32 at ths
rear portion of the body 28. The sub 501 has a first reduced
diameter portion 505 forming a shoulder 504. Tha rear por-
tion 505 of the sub 501 is smallar in diameter than the first
reduced diameter 503 forming a second shoulder 506. The rear
portion 505 extends longitudinally from shoulder 506 and has
~xt~rior threads 507 at th~ back end.
- 43 -
5~l
A thin cylindrical retainer ring 508 i~ received on
the reduced diameter 503 of sub 501 by scraws 509. The rear
end of ring 508 axtends a short distance beyond the shoulder
506 to surround the forward end of the rear portion 505 of
the sub 501.
An elongated hollow cylindrical rotating fin ~leave
i~ slidably and rotatably received within the extanded por-
tion of ring 508 and surrounds ths rsar portion 505 of sub
501. The fin sleeve 510 has a central longitudinal bore 511
and a counterbore 512 of larger diametsr 0xtending inwardly
from the back end and defining an annular shoulder 513. An
0-ring seal 514 on the fin ~leeve 510 provid0s a rotary and
reciprocating seal on th~ inner surface of the ring 508. A
plurality of circumferentially 6paced dowel pins 515 extend
radially inwardly through the side wall of the fin sl0eve 510
and terminate a short distance from ths oircumference of the
rear portion 505 of the sub 501. An 0-ring seal 516 and a
bushing 51~ are positioned on the interior surfacs of fin
~leeve 410 intermediata the dowel pins 515 and shoulder 613.
A plurality of radially and angularly opposed fins
518 are secursd to the exterior of the rotating fin sleeve
510 and extend radially outward therefrom. The fins 518 ara
securad at opposing angles relative to the longitudinal axis
of the ~leeve 510 to impart a rotational forcs on the sleeve.
A tubular cap 519 having a central bore 520 and a
threaded counterbore 521 extending inwardly from the front
~.ZS~;6~
end is slidably recsived on the air distribution tube 46 and
the sub rear portion 505 within the fin sleeve 510. The cap
519 is threadedly recsived and secured on th0 threads 50~ at
the snd of the sub 501. The cap 519 has a raduced diameter
front portion 522 and an enlarged diameter rear portion 523
forming a shoulder 524 therebetwaen. A pair of longitudin-
ally spaced O-rings 525 are provided on the rear portion 5~3
and a bushing 526 is provided intermediate the O-rings 525.
The enlarged diameter rear portion 523 o~ cap 519 ls
rotatably received within the counterbore 512 with O-rings
525 providing a rotary seal. A8 pr0viously shown and des-
cribed with reference to ~ig. 22, a plurality of drive teeth
428 are formsd on the front end of the cap 519. The rear
portion 523 of the cap 519 has a raduced diametar portion 52~
which removably receives a conical cover member 528. A plur-
&lity of circumferentially spaced longitudinal bore~ 529
extend through the rear portion of the cap 519 for communica-
tlng the interior of the body 28 with ~tmosphere. The drive
taeth ara oonstructed and operate as pr0viously describad for
the other embodiments.
When properly positionad, an annular chamber 530 is
formed between the shoulder 513 of the fin sleeve and the
shouldar 524 o~ the cap and sealed at each end by th0 O-rings
516 and 624. A threaded bore 433 at the back end o~ the cap
519 r0ceives a hose fitting (not shown) and a small pas~age-
- 45 -
~2S~S~
way 434 extends inwardly from the threaded bore to communi-
cat0 the annular chamber 530 with a fluid or air aourca (not
shown) for effecting reciprocation of the fin sleeve 510.
The operation of the tail fin assambly with dowel
pins and drive teeth i~ be~t seen with referance to Figs 23
and 24. Compressed air or fluid in tha annular chamber 530
moves the fin slaeve 510 toward the front of the sub 501. In
lts foremost position, the front end of the sleavs 510 con-
tacts the shoulder 506 and the dowel pins 515 disengage from
the drive teeth 428. In this position (Fig. 23), compressed
air or fluid i8 admittsd through the passage 454 from the
source into the annular chamber 530. The fin sleeve 510 is
then free to rotate rslative to the tool body.
When the air or fluid pressure within the chamber 530
is relieved, the driving force of the tool hammer carries the
tool ln¢luding the oap 519 forward (Fig. 24). During this
movement, the drive teeth 428 and dowel pins 515 engage once
again and the fin sleeve 510 i9 locked against rotational
movement relative to the tool body. The cycl0 may be select-
ively repeated as necessary for proper aligmnent of theslanted nose member and attitude adjustment of the tool.
A STILL FURTHER EMBODIMENT
Flgs. 25 and 26 are partial longitudlnal cross sec-
tional views of a variation of the fixed/lockable fin assem-
bly using an interlocking lug arrangement to prevent rota-
- 46 -
3LZ~S~
tional movement. The tail fin assembly 600 comprises a c~l-
indrical connecting sub 601 having external threads at the
front end which are received within the internal threads at
the rear portion of the body (not shown). The circumfsrence
of the sub 601 ha6 a first rsduced diameter portion 602 form-
ing a ~irst shoulder 603. The rear portion 604 of the sub
661 is 6maller in diameter than the first reduc~d diametsr
602 forming a second shoulder 605. An annular raised sur~ace
606 on the rear portion 604 is spaced rearwardly from the
shoulder 605 and provided with a series of circumferentially
6paced slots 607 forming a series o~ raised lugs or splines
608. The rear portion 604 extends longitudinally from the
lug5 608 and iB provided with exterior threads 609 at the
back end. ~n annular 0-ring seal 610 is providad on the rear
portion 604 lnwardly of the threads 609.
A thin cylindrical retainer ring 508 is received on
tha fir~t redu¢0d diameter 602 o~ the sub 601 by screws 509.
The rear end of the r1ng 508 extends a short distance beyond
the shoulder 60~ to surround the ~orward end of the rear por-
tion 604 of the sub 601.
An elongated hollow cylindrical rotating fin sleeve
611 iB slida~ly and rotatably receivad within tha extended
portion of th0 ring 508 and 6urrounds the rear portion 604 o~
the sub 601. The fin sleeve 611 has a central longitudinal
bore 612, a front and rear counterbore 613 and 614 rsspsct-
- 47 -
;6~3~
ivaly of larger diameter extending inwardly from each end and
dsfining annular 6houlders 615 and 616 therebetween. An an-
nular 0-ring seal 617 and annular bushing 618 are disposed on
central bors 612 intermediate the shoulders 615 and 616, A
reduced diameter 619 is provided on tha inner diameter of tha
front counterbore 613 near the front end and provided with a
seri~ of circumferentially spaced slots 620 forming a ~eriaR
of raisad lugs or ~plinas 621. An 0-ring seal 622 on the
outer circumference of the fin sleevs 611 provides a rotary
and reciproaating seal on the inner surface of the ring 508.
A plurality of radially and angularly opposed fins
518 are secured to the exterior of tha rotating fin sleave
611 to extend radially outward therefrom. The fins 518 are
secured at opposing angles relative to the longitudinal axis
of the sleeve 611 to impart a rotational force on the sleeve.
An elongated hollow oylindrical cap 623 having a
central bare 624 and a larger threaded bore 625 extending
inwardly from the front end i6 slidably received on the air
distribution tube 46 and threadedly secured on the threads
609 at th0 end of the sub 601. Th0 outer circumference of
the cap 623 is received within tha rear counterbore 614 of
the fin slaeve 611. A pair of longitudinally spaced annular
0-rings 626 ara provided on the outer circumfarenca of the
cap 623 and a bushing 62~ iR provided intarmediats 0-rings
626. Ths outer circumferenc0 of the cap 623 is rotatably
- 48 -
~z~s~
rec0ivad within the countsrbore 614 with th0 0-ringa 626
providing a rotary s0al therebetween. Ths rear portion of
the cap 623 has a reduced diamet0r portion 628 which remov-
ably receives a conical cover member 629. A plurality of
circum~ersntially spaced longitudinal bores 630 extend
through the r0ar portion o~ the cap for communicating the
interior o~ the tool body with atmosphere.
When properly positioned, an annular chamber 631 is
formed betwe~n the shoulder 616 of the fin slssve and the
forward 0nd of the cap 623 and sealed at 0ach end by the
0-rings 610, 617, and 626. A threaded bore 433 at the back
and of the cap 623 receives a hose fitting (not shown) and a
small passag6way 434 0xtends inwardly from the threaded bore
to communicate the annular chamber 631 with a fluid or air
source (not shown) for effecting r0ciprocation of the fin
9 leeve.
The operation of the tail fin assembly 600 i8 best
seen with reference to ~ig~. 25 and 26. Under action of
compressed air or fluid in the annular chamber 631 the fin
slQeve 611 beglns to move toward the front of the sub 601.
Whan in its foremost position, tha front end of the ~leeve
611 contacts the shoulder 605 and the lugs 608 and 621 become
disangaged. In this position (~ig. 25), compressed air or
fluid is admitted through the passage 434 from the source
into the annular chamber 631. Tha fin slesva 611 i8 thsn
free to rotate relativ0 to the tool body.
- 49 -
~s~s~
~ han the air or fluid pressure within the chambar 631
is relieved, the driving foroe of the tool hammer carries ths
tool including tha cap 623 forward (~ig. 26). During this
movement, the drive lugs or splines 608 and 821 become engag-
ed once again and the fin sleeve 611 becomes locked against
rotational movamsnt relative to the tool body. The cycle may
be selectively repeated as neces6ary for proper alignment of
thH slanted nose member and attitude adjustment of the tool.
A STILL FURTHER EMBODIMENT
0 ~igB. 27 and 28 are partial longitudinal cro6s sec-
tions of another variàtion of the fixed/lockable fin assembly
using a drive pin. The tail fin assembly 650 comprises a
cylindrical connecting 6ub 651 ha~ing external threads 652 at
the front end which are received wlthin the internal threads
15 32 at the r0ar portion of the body 28. The rear portion 653
of the 6ub 651 i8 smaller in diameter than the front portion
forming a shouldar 654. The rear portion 653 extends longitu-
dinally from the shoulder 654 and has interior threads 655 at
th~ back end.
A thin cylindrical retainer ring 656 is received on
the front portion of the sub 651 betw0en a raised shoulder
65r and the back end of the body 28. The raar end of the
ring 658 axtends a short distance beyond the raisad shoulder
65~ to 6urround the forward end of tha rear portion 853 o~
the 6ub 651. A plurality of circumferantially spaced dowel
- 50 -
~zs~
pins 4lr 0xtend radially outward through th0 side wall of the
rear portion 653 and terminate a short diatance from the
interior surface of the ring 656.
An elongated hollow cylindrical rotating fln sleeve
659 is slidably and rotatably received within the axtended
portion of the ring 656 and surrounds the rear portion 653 of
the ~ub 651 including the dowel pins 417. The fin sleeve 65
has a csntral longitudinal bore 660 and a counterbore 661 of
larger diameter extending inwardly from the bacX 0nd and
defining an annular shoulder 662 therebetween. An 0-ring
seal 663 on the outer circumference of the fin sleeve 65g
provide~ a rotary and reciprocating seal on the inner surface
of the ring 656. An annular 0-ring seal 664 and a pair of
bushings 668 are provided on the interior surface of the fin
15sleeve 659. A plurality of drive teeth 428 (as previously
shown and described) are formed on the front end of the fin
sleeva 659.
A plurality oI radlally and angularly opposed fins
666 are secured to the exterior of the rotating fin sleeve
20659 to extend radially outward therefrom. The fins 666 are
sacured at opposing angles rela~ive to the longitudinal axis
of the sleeve 659 to impart a rotational force on ths sleeve.
An elongated hollow cylindrical cap 66~ having a
central bore 668 and a counterbore 669 extsnding inwardly
from the front end is slidably received on the air distri-
- 51 -
~s~
bution tube 48 within the fin sleeve 659. Exterior threads
6~0 are provided on the front portion of the cap 667 which
are received on the threads 655 at the back end of the sub
651. The rear portion of the cap 667 i8 larger in diameter
than the threaded front portlon forming a shoulder 671 there-
between.
A pair of longitudinally spaced annular O-rings 672
are provided on the outer circumference of the r0ar portion
and a bushing 673 is pro~ided int~rmediate ths O-rings. T~e
anlarged diametsr rear portion of the cap 667 i~ rotatably
received within the counterbore 661 with the O-rings 6r2
providing a rotary seal therebetween. The rear portion of
th0 cap 667 removably receives a conical cover member 674.
To avoid repetition, the detailed description of the drive
teeth and their operation will not be repeated here.
When properly positioned, an annular chamber 675 is
formed between the shoulder 662 of the fin sleeve and the
~houlder 671 of the cap and sealed at each end by the O-rings
663 and 6~2. A threaded bore 433 at the back end of the cap
667 receives a hose fitting (not shown) and a small passage-
way 434 extends inwardly from the threaded bor0 to communi-
cate the annular chamber 6~5 with a fluid or air source (not
shown) for effecting r0ciprocation of the fin sleeve 659.
Fig. 28 6hows the locked position, and since the operation of
th0 tail fin assembly has b0en previously shown and explain-
ed, it will not ba repsated here.
- 52 -
S6S~
A STILL ~URTHER_EMBODIMENT
~ igs. 29 and 30 are partial longitudinal cross sec-
tions of another variation of the fixed/lockable fln asssmbly
using a series of slots or splin0s and dowel pins to prevent
rotational movement. The tail fin assembly 700 compri~as a
cylindrical connecting sub 701 having external threads 702 at
the front end which are received within the internal thraads
32 at the rear portion of the body 28. The circumference of
the sub 701 has a first reduced diameter portion 703 forming
a first shoulder 704 ther0between. A second reduced diameter
705 forms a second shoulder 706. A third reduced diameter
707 forms a third reduced diameter 708. An enlarged diameter
709 approximately the same diameter as the second is spaced
therefrom and provided with a series of circumferentially
spaced slots 710 defining a 6eries of raised lugs or splines
711 on the third reduced diameter 707. A fourth diameter 712
smaller than the third forms a fourth shoulder 714 therebs-
tween. The fourth diameter 712 extends longitudinally from
the ~houlder 714 and is provided with exterior threads 715 at
the back end.
A thin cylindrical retainer ring 716 is received on
the first reduced diameter 703 of the sub 701 by screws 717.
The rear end of the ring 716 e~tends a short distance beyond
the shoulder 706 to surround the forward end of the reduced
25 diameter 705. A rod wiper 718 is oontained on the interior
of the rear end of tha ring 716.
- 53 -
~;~5~X~
An alongatsd hollow cylindrical rotating fin aleeve
719 i8 ~lidably and rotatably recsived within the extsnded
portion of the ring 716 and surrounds the rear portion of ths
sub 701. The fin sleev0 719 has a cen$ral longitudinal bore
5720, a fron~ and rear counterbor0 721 and 722 respectively of
largar diam0t0r extending lnwardly from each end and defining
annular shoulders 823 and q24 therebetwaen. An annular bush-
ing 725 is dispos0d on the inner diamet0r of the counterbore
7~1 and a rod wiper 728 is provided on th0 inner diameter of
tha counterbor0 722. A plurality of circumfsr0ntially spaced
dowel pins 727 0xt0nd radially inwardly through th0 sids wall
of the fin sleeve 719 and terminate a short distancs from the
circumference of the third reduced diameter 707 of th0 sub
701. An annular bushing 728 iB provided on the central bore
15q20 intermediate the shoulders 723 and 724.
A plur~lity of radially and angularly opposed fins
729 are secured to the exterior of ths rotating fin sleevs
719 to extand radially outward therefrom. The fins 729 are
~ecured at opposing angles relative to the longitudinal axis
of the sleeve rl9 to impart a rotational force on th0 sleeve.
An elongated hollow cylindrical cap 730 having a
central bore 731 provided with interior thr0ads 732 and a
counterbore 733 s~tending inwardly from the front end is re-
ceivad on the threads 715 of the sub 701 and within th0
25counterbore 722 of the -fin sleeve 719. An annular O-ring 734
- 54 -
~2~5~5~
on the bore 731 provides a seal on the fourth reduced diame-
ter 712 of the 6ub ~01. A cylindrical reciprocating piston
735 is ~lidably reeived on the fourth reduced diameter 712 of
the 6ub 701 and within the counterbore 733 of the cap 730.
Annular 0-rings 736 and 737 are provided on the inner and
outer diameters respectively of the piston 735.
With the piston 735 propsrly positioned, an annular
chamber 736 is formed between the fourth reducsd diametar 712
and the counterbore 733 and sealed at each end by the 0-rings
754, 736 and 737. A threaded bore 433 at the bac~ end of the
cap 730 re¢aives a hose fitting (not shown) and a small
passageway 434 extands inwardly from the threaded bore to
communicate the annular chamber 736 with a fluid or air
source (not shown) for effecting reciprocation of the piston
735 and fin sleeve 719.
The operation of the tail fin assembly 700 is best
seen with referenoe to ~igs. 29 and 30. ~nder action of
compressed air or fluid in tha annular chambar 736 the piston
73~ begins to move toward the front of the sub 701 and con-
tacts the shoulder 724 of the fin sleeve 719 carr~ing it
forward. When in its foremost position, the front end of the
piston 735 contact6 the shoulder 714 and the dowel pins 727
become disengaged from the slots or spline6 810. In thi6
position ~Fig. 29), compressed air or fluid is admitted
through the passage 434 from the source into th~ annular
- 55 -
~2~
chamber 736. The fin sleeve ~19 is then free to rotate rela-
tive to the tool body.
When the air or fluid pressura within the chamber 736
i6 relieved, the driving force of the tool hammer carries the
tool including the sub 701 ~orward relative to the fin sleeve
719 (Fig. 24). During thia mo~ement, the 6houlder 724 move6
tha plston rearwardly and the dowel pins 727 become sngaged
oncs again in the 610ts 710 and the fin 61eeve 719 becomss
lo¢ked against rotational movement relative to the tool body.
The cycle may be selectively repeated a~ nece6sary for proper
alignment of the slanted no~e member and attitude ad~ustment
o~ th0 tool.
A STILL FURTHER EMBODIMENT
Figs. 31 and 32 are partial longitudinal cro6s sec-
tion6 of another variation o~ the fixed/lockabls fin a6semblyusing a serie6 of slot6 or spline6 and dowel pins to prevent
rotational movement. The tail fin as6embly 750 comprises a
cylindrical connecting ~ub 751 having external threads 752 at
the front end which are received within the internal thread6
32 at the rear portion of the body 28. The circumference of
the 6ub 751 ha6 a fir6t reduced dlameter portion 753 formlng
a first 6houlder 754 therebetween. A second reduced diameter
755 forms a second shouldar 906. A third reduced diamster
757 forms a third shouldar 758. An enlarged diameter 759
approximatsly the 6ams diameter as the second is ~paced
- 56 -
~2SS~
tharefrom and provided with a serias of circumferentially
spaced slots 760 defining a series of raised lugs or splins~
761 on the third reduced diameter 757. The third diametsr
757 extends longitudinally from the lugs or splines 761 and
i~ provided with exterior threads 762 at th0 baok and.
A th~n cylindrical retainer ring 763 is received on
the first reduced diameter 753 of the sub 751 by screws 754.
The rear and of the ring 763 extends a short distance beyond
the shoulder 756 to surround the forward end of the reduced
diameter 755. A rod wipsr 765 is contained on the interior
of the rear end of ths ring 763.
An elongated hollow cylindrical rotating fin sleeve
766 is slidably and rotatably received within the extended
portion oI the ring 763 and surrounds the rear portion of the
~ub 751. The fin sleeve 766 has a central longitudinal bore
767, a front and rear counterbore 768 and 769 respectively of
larger diameter extending inwardly from each end and defining
annular shoulders 770 and 77l therebetween. An annular bu6h-
ing 772. is disposed on the inner diameter of the counterbore
768 and a rod wiper 773 is provided on the inner diameter of
the rear counterbore 769. A plurality of circumferentially
spaced dowel pins 774 extend radially in~ardly through the
side ~all of ths fin sleeve 766 and terminate a short dist-
ance from the circumf0renca of the third reduced diameter ~57
of the sub 75l.
- 57 -
~s~
A plurality of radially and angularly oppossd fins
775 are secured to the exterior of the rotating fin slssve
766 to extend radially outward thsrefrom. Tha flns 77~ are
~scured at opposing anglss relative to the longitud$nal axis
5of ths sle3Ya ~66 to impart a rotational force on the sle~vs.
An elongatsd hollow cylindrical cap 776 havlng a cen-
tral bors ~77 provlded with intsrior threads 778 and a count-
srbore 779 extsnding lnwardly from ths front end is rscaived
on th~ thr~ads 762 of th0 sub 751 and w$thin th~ counterbore
1076~ of ths fin slesve 766. An annular 0 ring 780 on ths bors
r77 provides a ssal on th~ third rsducsd diamstsr 757 of th~
sub 7Bl. An annular bushing 781 is providsd on ths circum-
fer~ncs of the cap 776. A cylindrical raciprocating plston
782 is slidably rsceived on the third reduced diamstsr 757 of
15the sub 751 and within the count0rbore 769 of the cap 778. A
rsducsd diamstsr 783 at the front end of ths piston i8 rs-
csived within the central bore 767 of ths fin sleeve 766.
Annular 0-rings 784 and 785 ars provid~d on ths innsr and
outsr diameters rs6pectivsly of the piston 781.
20With th~ plston 781 propsrly positionsd, an annular
chamber 786 i6 formsd between ths circumfsrsncs of ths sub
751 and ths countsrbore 777 and sealsd at each snd by ths 0-
rings 780, 784 and 785. A thrsaded bors 433 at ths back snd
o~ ths cap 786 rscsives a hose fitting (not shown) and a
25small passagsway 434 extends inwardly from the thrsad~d bors
- 58 -
~Z~5~
to communicate the annular chamber 785 with a fluid or air
source (not shown) for affecting reciprocation of the piston
78~ and fin slseva 766.
Tha operation of the tail fln assembly 750 ls best
seen with reference to ~igs. 31 and 32. Undar action of
compressed air or fluid in the annular chamber 786 the piston
782 begins to move toward the front of the sub 751 and
carrias the fin sleeve 766 with it. When in its foremost
position, the front end of the piston 782 contacts the lugs
or splines 761 and the dowel plns 774 become disengaged from
tha slots 760. In this position (fig. 31), compressed air or
fluid i9 admitted through the passag0 434 from the source
into the annular chamber 786. The fin slaeve 766 is thsn
free to rotate relatlve to the tool body.
When tha air or fluid pressure within the chambar 786
is relieved, the driving force of the tool hammer carries the
tool including the sub 751 forward relative to tha fin sleeve
766 (Fig. 32). During this movemant, the shouldsr 771 moves
the piston rearwardly and the dowel pins 774 become engaged
once again in the slots or splines 760 and ths ~in sleeve 766
b~¢omes locked again~t rotational movement relative to ths
tool body. The cycle may be selectively repeatsd as necess-
ary for proper alignment of the slanted nose membsr and atti-
tuda ad~ustment of the tool.
- 59 -
~L2~ 5~
A STILL FURTHER EMBODIMENT
Figs. 33 and 34 are partial longitudinal cross BeC-
tions of another variation of the ~ixed/lockable fin assembly
using a serias of dowel pins and drive teeth to prevent rota-
tional movement. The tail fin as6embly 800 compriss~ a cyl-
indrical connecting sub 801 having sxternal threads 802 at
the front end which are receivad withi~ the lnternal threads
at ths rear portion of the kool body. Th0 circumfersnce of
the ~ub 801 has a first reduced diameter portion 803, and a
10second reduced diameter 804 forms a shouldar 805 therebe-
twean. A third reducad diametar 806 forms a third shoulder
807. The third diameter 806 extends longitudinally from the
shoulder 807 and is provided with exterior threads 808 at the
ba¢k end.
15A thin cylindrical retainer ring 809 ia received on
the first reduced diameter 803 of the sub 801 by screws 810.
The raar end of the ring 809 extends a short distance beyond
the shoulder 805 to surround the forward end of the reduced
diameter 804. A rod wiper 811 is contained on the interior
of the rear end of the ring 809.
An elongated hollow cylindrical rotating fin sleeve
812 has a central longitudial bore 813, and a rear counter-
bore 814 of larger diameter extending inwardly from khe back
end and defining an annular shoulder 815 therebetwaen. An
annular bushing 816 is provided on the central bore and an-
- 60 -
65~L
other bushing 817 i~ provided on the counterbore 814. The
outer circumference of th~ fin sleeve 812 is providad with
front reduced diam~ter 818 and a rear reduced diameter 819.
The fin sleeve B12 is slidably and rotatably received on the
sub 801 with the cantral bora 813 on the second raduced dia-
metsr 804 and tha front reduced diameter 818 wlthin the ex~
tand~d portion of the ring 809. A series of drive t0eth 428
previously shown and describad with reference to Fig. 22 are
formed on tha back end of the fin sleeve 812.
A plurality of radially alld angularly opposed fins
820 are secured to the exterior of the rotating fin sleeve
812 to axtsnd radially outward therefrom. The fins 820 are
secured at opposing angles ralative to the longitudinal axis
of the sleeve 812 to impart a rotational forc0 on the sleeve.
An elongatad hollow cylindrical cap 821 having a
cantral bore 822 provided with interior thrsads 823 and a
¢ounterbors 824 extending inwardly from the front end and
defining a shoulder 825 therebetween is racsived on the
thread~ 808 of the sub 801 and within ths counterbora 814 of
the fin sleeve 812. An annular 0-ring 826 on the bora 822
providss a seal on the third r~duced diameter 806 of the sub
801, and another 0-ring 82~ on tha counterbore 814 provides a
ssal on ths reduced portion of a piston member describad
hareinaftar. A plurality of circumferentially spacad dowel
pins 828 extand radially outward through the ~ide wall of the
fin slsave 812 (shown out of position).
- 61 -
~z~
A cylindrlcal reclprocating piston 829 is slidably
received on the third reduced diameter 806 of ths sub 801.
The rear portion 830 of the piston 829 i8 amaller in diameter
than the outer circumference defining a shoulder 831 there-
between. The outer circumference of ths piston 8Z9 is re-
ceived in the annulus between the third rsduc~d diameter 806
and the fin ~leeve counterbore 814 and the rear portion 830
i8 receivad in the annulus between the third raduced diamatsr
806 and countsrbore 824 of the cap 821. An annular 0-ring
10 832 is provided on the inner diam0ter of the piston 829.
With the piston 829 properly positioned, an annular chamber
833 i~ formed between the back end of the piston and the
counterbore 824 of the cap 821 and sealed by the 0-rings 826,
82~, and 832.
A threaded bore 433 at tha back end of the cap 821
receives a hose fitting ~not shown) and a small psssageway
434 extends inwardly from the threaded bore to communicate
the annular chamber 833 with a fluid or alr source (not
shown) for effecting reciprocation of the piston 829 ~nd fin
20 8leeve 812.
A second thin cylindrlcal retainer ring 834 is se-
cured on the rear reduced diameter 819 of the fin sleeve 812
by screws 835 and extends rearwardly to surround the drive
teeth 428 and the dowel pins 828 . The rear end of the ring
25 834 extends a distance beyond the dowel pins 828 and is pro-
vided with a rod wiper 836.
~ 62 -
~s~
The operation of the tail fin assembly 800 is bsst
ssen with referen¢e to Figs. 33 and 34. Under action of
compressed alr or fluid in the annular chamber 833 the piston
829 begins to move toward the front of th0 sub 801 contacting
5the shoulder 815 and carrying the fin sleeve 812 with it.
When in it~ foremost position, the front end of the pigton
829 contacts the shoulder 815 and the drive teeth ecome dis-
engaged $rom th0 dowel pins 828. In this position (Fig. 33),
compres6ed air or fluid i8 admitted through the passage 434
10from the source into the annular chamber 833. The fin sleeva
812 i~ th~n free to rotate relative to the tool body.
When the air or fluid pressur~ within the chamber 833
is ralievsd, the driving force of the tool hammer carrie~ the
tool including the sub 801 forward relative to the fin slesve
15812 (Fig. 34). During this movement, the shoulder 815 moves
the piston rearwardly and the drive teeth 428 become engaged
once again with the dowel pins 828 and the fin sleeve 812
becomes locked agalnst rotational movemant relative to the
tool body. The cycle may be selectively rspe~ted as necess-
ary for proper alignment of the slanted no~e member and atti-
tude ad~ustment of the tool.
A STILL FIJRTHER EMBODIMENT
Fig. 35 is a longitudinal cross sectional view of a
movable tail fin assembly. Fig. 36 is a vertical cross sec-
tional view of the movable tail fin assembly of Fig. 35 taken
- 63 -
~X~53L
along line 36 - 3B o~ Fig . 36 . The mo~abl e tall ~in arrange-
mant i8 similar to the fixad/lockable tall fins previously
described with the exception that it rotates the boring tool
through an inclined, anti-parallel or skewed fin arrangement.
When the two fins ara parall01, the soil forces acting on
their faces prevents rotation of tho tool housing and allows
the nose member or eccentric hammer to produce a net deflec-
tiv0 force which causes the tool to veer in a curved tra~ec-
tory.
10The movable tail fin assembly 900 comprises a cylin-
drical connecting sub 901 having external threads at the
front and which are reoeived within the internal threads at
the rear portion of the tool body. The outer rear portion of
the sub 001 i8 reduced in diameter defining a shoulder 902
and provided with external threads 90~. A series of
ciroumferentialy spaced openings 904 extend radially through
the side wall of the sub 901 communicatng the interior of the
tool to atmosphere. A pair of opposed J-slots 905 extend
longitudinally inward from the back end of the sub 901 and
terminate a distance from the openings 904.
An annular 0-ring seal 906 on the c~ntral bore 90
provides a seal on the air distribution tube 46. ~ circular
opening 908 axtends transversly through the rear portion of
the sub 901 and the J-slots 905. In annular arcuata grooYe
25909 i~ formed in the interior of each circular opening 908
- 64 -
~s~
spaced outwardly ~rom each ~ide of the slots 905 and concen-
tric with the opening 008, and a small opening 910 extends
from each groove to the outer aurface o~ the sub 901. Ths
opening~ are used to fill the grooves with ball bearinga 911
after which they ara 0nclosed by threaded plugs 912,
A piston spool 913 is slidably received on the air
distribution tube 46. The piston spool 913 comprisss an
elongated cylindrical member having a c0ntral longitudinal
bore 014 with an 0-ring seal 915 near the back end to seal on
the tube 46. Ths front portion of the spool 913 is in the
~orm of a tubular extension 916 and has a short reduced dia-
meter 917 at the ~orward end. The rear portion of the Rpool
has an enlarged diameter 918 greater than the extension 916
to define a shoulder 919 therebetween. An 0-ring seal 920 is
provided on the enlarged dlameter 918. A pair of radially
opposed threaded bores 921 and 922 extend longitudinally
through the rear portion o~ the spool 913 to receive hose
fittings for connection to an air or fluid source (not
shown).
A ¢ylindrical piston 923 having a central bore 924 is
slidably mounted on the circumference of the tubular exten-
sion 916. A pair of radially opposed bores 925 and 926 in
axial alignment with the bores 921 and 922 extend longitudin-
ally through the piston 923 and are provided with internal
25 threads 92~ at the rear portion. An 0-ring seal 928 disposed
in the central bore 924 provides a reciprocating seal on the
- 65 -
~ZS5G~
tubular extsnsion 916. Another 0-ring saal 929 i8 proYided
on th~ ¢ir¢umference of ths pi 6 ton 923.
A cylindrical bulkhead 930 having a central bore 931
is mounted on the forward end of the tubular extension 91B.
A pair of radially opposed bores 932 and 933 in axial align-
ment with the bora~ g25 and 926 extend longitudinally through
tha bulkh~ad 930 and are provided with intarnal 0-ring seal6
934. An 0-ring seal 935 disposed in the cantral bore 931
provids6 ~ seal on tubular extension 916. Anoth~r 0-ring
saal 936 i8 provided on the circumference of the bulkhaad
930. A slot 937 extends vertically through one side wall of
the bulXhead at the forward and and receives a raotangular
key 938 for keying the bulkhead to the back end of sub 901.
An actuating rod 939 having a flat rectangular front
portion 940 and a longitudinally offset round tail portion
041 is carried by the piston 923. The front portion of the
actuating rod 939 is slidably recived in the elongated por-
tion of the J-slot 90B and the tail portion 941 extends out-
wardly th~refrom to be slidably received through the bulkhead
bore 932 and provided with external threads at the rear snd
which are received on the threads 927 of tha bore 925 in the
piston 923. The rectangular front portion 940 is provid0d
with a transvarse slot 942 which engages tha protruding lug
of ~ cup-shap~d mamber described hereinafter. An 0-ring seal
~48 is di6possd on the circumfarence of the tail portion 941
to provida a ssal on the piston bore 925.
3 25S6~
Similarly, a longer, rev0rse actuating rod 943 havlng
a flat reatangular front portion 944 and a longitudinally
offset round tail portion 943 is carried by the piston 923.
The front portion of the actuating rod 943 is slidably re~
cived in the elongated portion of the opposing d-slot 905 and
the tail portion 945 extends outwardly therefrom to be slid-
ably received through the opposed bulkhead bore 033 and pro-
vided with axternal threads which are received on tha threads
92~ of the bore 926 in the piston 923. A reduced diameter
946 extends rearwardly from the threads 92~ and i8 slidably
received within the bore 922 of the piston spool 913. The
rectangular front portion 944 is providad with a transverse
slot 04r whioh engages the protruding lug of another cup-
shaped member (hereinafter described). An 0-ring seal 948 is
disposed on the circumference of the tail portion 945 to pro-
vide a seal on the plston bor0 926.
An elongated hollow cylindrical outer sleeve 949 is
slidably receiv0d on the outer periphery of the bulkhead 930,
the piston 923, and the piston sleeve 913. The outer sleave
949 has interior threads 950 at the front portion, a central
longitudinal bore 951 0xtending therefrom and terminating at
a reduced bore 952 defining an annular shoulder 953 therebe-
tween. The outer sleeve 949 i8 threadedly received on the
threaded portion of tha sub 901 with a seal 954 provided
between the front end and the sub shoulder 902. A pair of
- 67 -
~S6~1
clrcular openings 955 extend transversly through thfl side
wall of the sleeva in axial alignment with the opening 908 to
receive the cup-shaped members (described hflreinafter). The
reducfld bore 952 is r~ceived on a short reduced diameter 956
of the piston spool 913 and the 0-rings 9Z0, 920, and 936
providing a seal on the central bore 951.
In this manner, the abov0 mantioned components are
encloead, and the sida wall of the slflev~ form~ a sealed
front chamber 957 betwflen the bulkhead 930 and the piston
923. A second rear chamber 958 is formed between the piston
923 and th~ piston 61eeve 913. A small passageway 059 ex-
tends inwardly from the back end of the revarse actuating rod
943 and communicates the bore 922 of the piston sleeve 913
with ths front chamber 96r. The oRposed bore 921 of the
piston sleeve 913 i8 in communication with tha rflar chamber
9B8. It should be understood that the opposed bores 921 and
922 at the back end of the plston sle0vs receive hose i~it-
tings and flexible hoses sxtend outwardly therefrom and to be
connectad to the fiuid or air source for effecting reciproca-
tion of the piston.
A pair of Rteering fins 960 and 961 each comprising a
flat rectangular fin 962 sscured to a cylindrical cup-shapfld
membar 963 and 964 ara rotatably r0ceived within the trans-
verse circular openings 908 and 955. Each cup-shapfld member
i8 provided with an annular 0-ring seal 965 to provida a
- 68 -
~2SS~5~
rotary saal on th0 interior of the opening 908, and a clr¢um-
ferential srcuate groove 966 in alignment with the grooves
909 to rec~ira the ball bearings 9ll. After tha bearings 911
are placed in th0 grooves, the tail fins are locked against
outward mo~ement, and ara free to rotat0 about the transverse
axis within the openings. Th0 opposed cylindrical enda of
the cup-ahaped Members 963 and 964 0xtend inwardly to meet at
the center of the sub 90l.
An arcuate eliptical cut-away portion extends trana-
versly across the ends of each cup-shaped member leaving a
flat raised segment 967 and a dimatrically opposed protruding
lug 968 whiCh is disposed angularly r~lative to tha longitud-
inal axis of the r0ctangular fin 962. In this manner, when
the cylindrical ends are in contact, the lugs 968 ara diamst-
rically opposed and the elliptical opening surrounds the airdistribution tube 46, whether the fins are rotated to a pos-
ition parallel or angularly disposed relative to the longit-
udinal axis of the tool. One lug is received in the ~lot 942
of the actuating rod and the oppo~ing lug is received within
the alot 947 of the reverse actuating rod.
Th0 operation of the movable tail fin assembly is
best seen with reference to Figs. 35, 37, and 38. Under
action of compr0ssed air or fluid in tha front chamber 957,
the piston 923 moves toward the back of the sub 90l carrying
25 the actuating rods 939 and 943 with it. This action causes
- 69 -
~5~S3l
the cup-shaped members 963 and 964 to rotate in opposlte
directions relative to the transverse axis. When in it~
rearmost position, tha air or fluid in the rear chamb0r ~58
ha~ been relieved or exhausted. In this position (Fig. ~5),
the fins are positioned angularly relative to the longitudi-
nal axis of the tool body. When the two fins ara inclined in
opposit0 directions, the ~oil ~orces acting on their faces
causes the tool housing to rotate about it~ longitudinal axis
and the tool bores in a straight direction.
When the air or fluid pres6ure within the rear cham-
ber 958 i8 relieved, the front chamber 95~ is pressurized to
move the pistons ln the opposite direction (~igs. 37 and 38).
In this position, the fins are positioned parallel to the
longitudinal axis of the tool body. In this position, the
flns prevent rotation of tha tool housing and the tool boras
in a curved direction as a result of the asymmetric boring
foroe of the slanted nose member or the eccentric hammer.
The positioning oi the fins in parallel or anti-par-
allel positions may be selectively changed as nece6sary for
proper alignment and attitude ad~ustment of the tool.
Figs. 40 and ~1 are longitudinal cross sections of a
portion of a boring tool including an eccentric hammer ar-
rangement. An off-axis or eccentric hammar may be used in
combination with the tail fin arrangements described prsv-
iously. When the center o~ ma6g of tha hammer is allowed to
- 70 -
S~
strike the lnner anvil at a point radially offset from the
longitudinal axis of the tool, a deflectiva sid0 force re-
sults. This force causes the boring tool to deviate in the
direction opposite to the impact point as depi¢ted in ~ig.
40. Orientation may be controllsd by the external rotation
of the tool body with tail ~ins. The only internal modif~-
¢ation required is the replacem0nt of the existing hammer.
~ ig. 40 ~hows tha front portion dstails of a boring
tool 23 whi¢h was shown previously in s¢hematl¢ form in Fig.
8 with a movable tail fin system in ¢ombination with an ec-
¢entri¢ hammer 24. Tha rear portion of the hammer 24 is not
shown, with the und3rstanding that the rear portion of the
hammer 24 would be the same as the ¢on¢entri¢ hammer 3~ shown
in Fig 9B. The rear portion o~ the tool is not shown in
Figs. 40 or 41 sin¢e the ec¢entri¢ hammer may bs used in
¢ombination with either the fix3d/lo¢kable fin systems or the
movable fin systems and with or without th3 slanted nose
member previously shown and des¢ribed.
Referring now to Figs. 40, 41 and 9B, th0 boring tool
23 comprises an elongated hollow cylindrical outer housing or
body 25. The outer front end of the body 25 tapers inwardly
forming a ¢onical portion 29. The int3rnal diameter of the
body 23 tapers inwardly near the front end forming a ¢onical
surface 30 which terminates in a redu¢ed diameter 31 extend-
ing longitudinally inward from the front end. The rear end
- 71 -
s~
of tha body is provided with internal threads for receiving a
tail fin a6sembly previously described.
An anvil 33 having a conical back portion 3~c and an
elongated cylindrical front portion 35 i8 contained within
the i'ront end of the body 23. The conical back portion 3~ of
the anvil 33 forms and interference fit on th3 conical sur-
face 30 of the body 23, and the elongated cylindrical portion
35 extends outwardly a distance beyond the front end of the
body. ~ flat surface 36 at the back end of anvil 33 recaive6
the impact of sccentric reciprocating hammer 24.
A slanted nose member 18 having a cylindrical back
portion 52 and a central cylindrical bore 53 extending in-
wardly therefrom may be secured on the cylindrical portion 35
of the anvil 53 (Fig. 40). A slot 54 through the sidewall of
the cylindrical portion 51 extends longitudinally substanti-
ally the length of the central bore 53 and a transverse slot
~5 extends radially from the bore 53 to the outer circumfer-
ence of the cylindrical portion, providing flexibility to the
cylindrica,l portion for clamping the nose member to the an-
vil. Longitudinally spaced holes in alignment with threadedbores 58 on the opposing side of the slot 54 receive scre~s
59 which s0cure the nose member 18 to the anvil 33. The
sidewall of the nose member 18 extends forward from the cyl-
indrical portion 62 and one side is milled to form a flat
inclined surface 60.
- 72 -
~ss~s~
Th3 accentric hammer 24 is an elongated cylindrical
memb~r slidably received within the internal diameter 38 of
the body 23. A substantial portion of the outer diametsr of
ths hammer 24 i6 smaller in diameter than the internal dia-
metar 38 of the body, forming an annular cavity 39 thereb~-
tween. The front portion of the hammer is constructed Ln a
manner to offset the center of gravity of the hammer with
re6pect to its longitudinal axis. As shown in Fig. 40, the
side wall of the hammer is provided with a longitudinal slot
970 which places the center of mass eccentric to the longi-
tudinal axis and the front surface 43 of the front end of the
hammer 24 is shap3d to provida an impact centrally on the
flat surface 36 of the anvil 33. In ~ig. 41, the ide wall
of the hammer 24a is provided with a longitudinal slot 9~0
and the front surface 43a is radially offset from the longi-
tudinal axis to place the center of mass eccentric to the
longitudinal axis and thereby deliver an eccentric impact
force on the anvil.
A series of longitudinal circumferentially spaced
slots 9~2 are provided on the outar surface of the front of
the hammer to allow passage of air or fluid from the front
end to the reduced diameter portion.
In order to assurs proper orientation of the hammer,
a key or pin 26 is secured through the side wall of the body
25 to extend radially inward and be received within the slot
- 73 -
~s~
~70 to maintain the larger mass of the hammer cn ona side of
the longitudinal axis of the tool.
As shown in Fig. 9C, a relatively shorter portion 40
at the back end of the hammer 37 i8 of largsr diameter to
provide a ~liding fit against the interior diameter 38 of the
body. A central cavity 41 extends longitudinally inward a
distance from the back end of the hammsr 37. A cylindrical
bushing 42 is ~lidablg disposed within the hammer cavity 41,
the circumferenca of which provides a aliding ~it against the
inner surface of the central cavlty 41.
Air passages 44 are provided through the sidewall of
the hammer 37 inwardly ad;acent the shorter rear portion 40
to oommunicate the central cavity 41 with the annular cavity
59. An air distribution tube 45 extends centrally through
the bushing 42 and its back end 46 axtends outwardly of the
body 28 and 18 connsGted by fitting6 47 to a flexibls hose
48. For eifecting raciprocation o~ the hammer 3~, the ~ir
di~tribution tube 4~ iB in permanent communication with a
compressed air source (not shown). The arrangement oi the
20 pa6sages 44 and the bushing 42 is such that, during recipro-
cation of the hammer 57, the alr distribution tube 45 alter-
nately communicates via the passages 44, the annular cavity
39 with either the central cavity 41 or atmosphere at regular
intarvals.
- 74 -
~2~5~5~
A cylindrical ~top member 49 is secured within the
inner diameter of the body 28 near ths back end and i8 pro-
vided with a series of longitudinally extsnding, circumfer-
entially spacsd passageways 50 ~or communicating the interior
of the body 28 with atmospher0. The air distrlbution tube 45
i8 centrally disposed within the stop member 49.
Under action of compressed air in the central cavity
41, the hammer 24 mov0a toward the front of the body 25.
When in its foremost position, the hammer imparts an impact
on the flat surface 36 of the anvil 33. In this position,
compre~sed air is admitted through the passagss 44 from the
central cavity 41 into the annular cavity 39. Since tha ef-
fective arsa of the hammer including the larger diameter rear
portion 40 is greater than the effective area of the central
cavity 41, the hammer starts moving in the opposite direct-
ion. During this movement, the bushing 42 closes the passag-
es 44, thereby interrupting the admission of compressed air
into annular cavity 41. The hammer 3r continues its movsment
due to th~ expansion of the the air in the annular cavity 39
until the passages 44 are displacéd beyond the ends of the
bushing 42, and the annular cavity is placed to communication
to atmosphere through the holes 50 in the stop member 49. In
thi6 position, the air is exhausted from the annular cavity
39 through the passages 44 now above the trailing edge of the
bushing 42 and the holas 50 in the stop mamber 49. Than tha
cycle is repeatad.
- 75 -
~2~SI~S~
The eccentric hammer can be used for 6traight boring
b~ avera~in~ the deflective side force over 360 b~ rotatin~
the outer body. The ~ins provide orientation capabilities as
prevSously described and are brought into an unlocked rotat-
ing or straight parallel alignment position when executingturns. Straight boring of the tool i8 accomplished by activ-
ating the fins to a apin inducing position counteracting tha
tendency of the eccentric hammer to turn the tool.
I~hen the fins are in a position preventing the tool
housing from rotating the tool will turn under the influence
of the asymmetric boring forces. Either an eccantric hammer
or anvil ~ill producs the desired result, since the only re-
quirement is that the axis of impact does not pass through
tha frontal center of pressure.
STILL ANOTHER EMBODIMENT
This embodiment conslsts of an overgaga sleeve or
sleeves looated over a portion of the tool outer surface
which are affixed such that they can rotate but cannot slide
axially. This permits transmittal of the tool's axial impact
force from the tool to the soil while allowing free rotation
of the tool during spinning operations. Th0 overgage areas
are at the front and bac~ of the tool, or alternately, an un-
dergage s~ction in the center of the tool body. This under-
cut in the center of the tool permits a 2-point contact
(front and rear) of the tool's outer housing with the soil
- 76 -
SS6S~
wall ~s opposed to the line contact which occurs ~ithout tha
undarcut. The 2-point contact allows the tool to deviate in
an arc without distorting the round cross-sectional profile
of the pierced hole. Thus, for a given steering force at the
front and/or back of the tool, a higher rate of turning iB
possible since a small0r volume of soil is displaced.
In ~ig. 42, tharfl is shown a preferred guSded hori-
zontal boring tool 1010, having overgage body sactions, used
with a magnetic field attitude sensing system. The boring
tool 1010 may be used with various sensing systems, and a
magnetic attituds sensing system is dspicted generally as one
exampla. The usual procedur0 for using percussion moles is
to first lo¢ate and prepare the launching and retrieval pits.
The launching pit P should be dug slightly deeper than the
planned boring depth and larga enough to provide sufficient
movement for the operator. The boring tool 1010 i8 connected
to a pneumatic or hydraulic source ll, is then started in tha
soil, stopped and properly aligned, preferably with a sight-
ing frame and level. The tool is then restarted and boring
continued until the tool e~its into the retrieval pit (not
shown).
The boring tool 1010 may have a pair of eoils 12,
shown schematieally at the back end, one of which produees a
magnetic field parallel to the axis of the tool, and the
other produces a magnetic field transverse to the axis of the
-- 7' ?' --
~2~i5~
tool. These coils are intermittently excited by a low fra-
quency generator 13. To sense the attitude of the tool, two
coils 14 and 15 are positioned in tha pit P, the axes of
which are psrpendicular to the desired path of the tool. The
line perpendicular to the axes of the6e coils at the coil
intersectlon determine~ the boresite axis.
Outputs of thesQ coils can bs procassed to develop
the angle of the tool in both the horizontal and vertical
directions with respact to the boresite axis. U~ing the
transverse fisld, the same set of coil6 can ba utilized to
determina the angular rotat~on of the tool to provide suffi-
cient control for certain types of stesring systems. For
these systams, the angular rotation of the tool i8 displayed
along with the plane in which the tool is expected to steer
upon actuation of the guidance control system.
The mechanical guidance of the tool can also be con-
trolled at a display panel 16. From controls located at dis-
play panel 16, both the operation of the tool 1010 and the
pneumatic or hydraulic actuation of tha fins 1017 can be ac-
complished as described hereinafter.
As shown in Fig. 42, the boring tool 1010 includes asteering system comprising a slanted-faca nose member 1018
attached to the anvil 1033 of the tool to produce a turning
force on the tool and tail fins 1017 on a rotary housing
lOl9a on the trailing end of the tool which are adaptad to be
- 78 -
~S6~
selectively po6itionsd relative to the body of ths tool to
negate tha turning force. Turning forca may also be imparted
to tha tool by an internal sccentric hammer, as shown in Fig.
41, above, delivering an off-axis impact to the tool anvil.
~or turning the tool, the tail fins 1017 are moved
i.nto a positlon where they may spin about the longitudinal
axis of the tool 1010 and the slanted nose member 1018 or
eccantric hammer will deflect the tool in a given direction.
When the fins 1017 are moved to a position causing the tool
1010 to rotate about its longitudinal axis, the rotation will
negate the turning affect of the nose member 1018 or eccen-
tric hammer as well as provide a means for orienting the nose
piece into any given plane for subsequsnt turning or direct-
ion change.
The body of the tool 1010 has front 1021 and rear
1022 overgage body sections which giva improved performance
of the tool in angular or arcuate boring. These overgage
sections are fixed longitudinally on the tool body and may be
fixed against rotation or may be mounted on bearings ~hich
permit them to rotate.
The sta0ring system of the presant invention will
allow the operator to avoid damaging other underground serv-
ices (such as power cables) or to avoid placing underground
utilities where they may be damaged. The body construction
of the tool including the overgage sections cooperates with
the steering mechanism to give overall improved performance.
- 79 -
~s~
Figs. 43 through 46 illustrate various embodimsnts of
the boring tool with overgage sections on the tool body. In
Fig. 43, there is shown a boring tool 1010 having a body 1020
enclosing the percussion mechanism driving the tool. The
front end of body 1020 i6 tapered as at 1029 and has the
external portion 1035 of the anvil protruding tharefrom for
percussion boring.
Front sleeve 1021 and raar sleave 1022 are mounted on
tool body or housing 1020 by a shrink or interfersnce fit.
In thls embodiment, overgage sleeves 1021 and 1022 are both
fixed against longitudinal or rotational slippage. The
slseves may be pinned in place as indicated at 1024. The
rear body portion is connected to a hydraulic or air line for
supply of a pressurized operating fluid to the tool.
In ~ig. 44, there is shown another embodiment of the
boring tool in which one of the overgage sleeves is free to
rotate. In this embodiment, boring tool 1010 has a body 1020
enclosing the percussion mechanism driving the tool. The
front end of body 1020 is tapered as at 1029 and has the
external portion 1035 of the anvil protruding therefrom for
percus6ion boring.
Front sleeve 1021 is mounted on tool body or housing
1020 by a shrink or interference fit. The overgage sleeve
1021 is fixed against longitudinal or rotational slippage.
The sleeve 1021 may be piImed in placo as indicated at 1024.
The rear sleeve 1022 is mounted on body 1020 on bearings 1025
- 80 -
~Z~i5~5~
for rotary motion thereon. The rear body portion i3 connac-
ted to a hydraulic or air llne for supply of a pressurizsd
operating fluid to the tool.
In the embodiments of Figs. 43 and 44, the protruding
anvil portion 1035 was not provided with any special boring
surface. In the embodiments of Figs. 45 and 46, the tool has
a slanted nose m0mber which causes to tool to deviate ~rom a
straight boring path at an angle or along an arcuate path.
The rear of the tool has controllable fins which allow the
tool to move without rotation or to rotate about its longi-
tudinal a~is. This arrangement is described further belo~.
In Fig. 45, there is shown a boring tool 1010 having
a body 1020 enclosing the percussion mechanism driving the
tool. The front end of body 1020 is tapered as at 1029 and
has the external portion 1036 of the anvil protruding thare-
from for percussion boring. The protruding portion 105B of
the anvil has a slanted nose member 1018 secured thareon for
angular or arcuate boring.
Front sleeve 1021 and rear sleeve 1022 are mounted on
tool body or housing 1020 by a shrink or interference fit.
In this embodiment, the overgage sleeves 1021 and 1022 ars
both fixed against longitudinal or rotational ~lippage. The
sleeves may be pinned in place as indicated at 1024.
At the rear of body 1020, there is a rotatable hous-
ing 1019a on which there are fins 101~. The housing and fin
- 81 -
~2~i5S~
assembly is actuatable betw0en an inactive position in which
the tool does not rotate about its axis and an actuated posi-
tion whare the fins caus~ the tool to rotate. The rear body
portion i8 connected to a hydraulic or air line for supply of
a pressurized operating fluid to the tool.
In Fig. 46, there is shown another embodiment of the
boring tool in whioh one of the overgage sleeves is free to
rotat.e. In this embodiment, boring tool 1010 has a body 1020
enclosing the percussion mechanism driving the tool. The
10front end of body 1020 is taperad as at 1029 and has the
external portion 1035 of the anvil protruding therefrom for
percu6sion boring. The protruding portion 1055 of the anvil
has a slanted nose member 1018 secured thereon for angular or
arcuate boring.
15Front sleeve 1021 is mounted on tool body or housing
1020 by a shrink or interference fit. The overgage sleeve
1021 is fixed against longitudinal or rotational slippage.
The sleeve 1021 may be pinned in place as indicated at 1024.
The rear sleeve 1022 is mounted on the body 1020 on b0arings
1025 for rotary motion thereon.
At the rear of body 1020, there is a rotatabls hous-
ing 1019a on which there are f iIlS lolr . Tha housing and fin
assembly is actuatable batween an inactive position in which
the tool does not rotate about its axis and an actuated posi-
tion where the fins cause the tool to rotate. The rear bodyportion i6 connected to a hydraulic or air line for supply of
a pressurized operating fluid to the tool.
- 82 -
~2~56S~
Fi~s. 47A, 47B, and 47C illustrate a boring tool 1027
having a slanted nose member and fixed/lockable fin arrange-
mant as dascribed ganerally in raferenca to Figs. 1 and 2
above. As shown, boring tool 1010 comprigas an elongated
hollo~ cylindrical outer housing or body 1028. The out0r
front end of body 1028 tapars inwardly forming a conical por-
tion 1029. Sleeve member 1021 is s0cured on body member 1028
by a shrink or intarferance fit and is fixed against longitu-
dinal or rotary slippage as previously described. The out-
side diameter of body 1028 tapers inwardly near the front endforming a conical surface 1030 which terminates in a reducad
diam0ter 1031 extending longitudinally inward from the ~ront
end. The rear and of the body 1028 has intarnal threads 103
for raceiving a tail fin assembly (sea Fig. 47C).
An anvil 1033 having a conical back portion 1034 and
an elongated cylindrical front portion 1035 i8 poPitioned in
the front 0nd of body 1028. The conical back portion 1034 of
anvil 1033 forms an interference fit on tha conical surface
1030 of the body 1028, and the elongated cylindrical portion
1035 exte.nds outwardly a predetarmined distance beyond tha
front end of the body. A flat transv0rse surface 1036 at the
back end of the anvil 1033 receives the impact of a recipro-
cating hammer 1037~
Reciprocating hammer 1037 is an elongated cylindric-
al membar slidably received within the cylindrical recesR
1038 of thc body 1028. A substantial portion of the outer
~ 83 -
~l25S65~
diameter of the hammer 1037 iR smaller in diameter than the
reca~ 1038 of the body 1028, forming an annular cavity 103~
therebetween. A relativsly shorter portion 1040 at the back
end of hammer 1037 is of larger diameter to provide a ~liding
fit against the interior wall of rec0ss 1038 of body 1028.
A central cavity 1041 sxtends longitudinally inward a
distance from the back end of the hammer 1037. A cylindrical
bu6hing 1042 i8 slidably disposed within the hammer cavity
1041, the circumference of which provides a sliding fit
against the inner surface of the central cavity 1041. The
front surface 1043 of the front end of the hammer 1037 is
shaped to provide an impact centrally on the flat surface
1036 of the anvil 1033. As described abov0, the hammer con-
figuration may also be adapted to deliver an eccentric impact
force on the anvil.
Air passages 1044 in the sid0wall of hammer 1037 in-
wardly adJacent the shorter rear portion 1040 communicats the
central cavity 1041 with the annular cavity 1039. An air
distribution tube 1046 e~tends centrally through the bushing
1042 and has a back end 1046 e~tending outwardly of the body
1028 connected by fittings 1047 to a flexible hose 1048. For
reciprocating the hammer 1037, the air distribution tube 1045
i~ in permanent communication with a compr0ssed air source 11
(Fig. 42). The arrangement of the passages 1044 and the
bushing 1042 is such that, during reciprocation of the hammer
- 84 -
~;~S5~
103~, the air distribution tube 1045 alternately communicates
via the pa~sages 1044, thfl annular cavity 1039 with either
the central cavity 1041 or atmosphere at regular intervals.
A cylindrical stop member 1049 is secured within the
recess 1038 in the body 1028 near the back end and has a
series of longitudinally-extanding, circumferentially-spaced
passageways lOB0 for exhausting the interior of the body 1028
to atmosphere and a c0ntral passag0 through which the air
distribution tube 1045 extends.
A slantsd nose member 1018 has a cylindrically ra-
cessed portion 1052 with a central cylindrical bore 1053
thsrsin which is receivsd on the cylindrical portion 1035 of
the anvil 1033 (~ig. 4~A). A slot 1054 through the sidewall
of the cylindrical portion 1018 extends longitudinally sub-
6tantiall~ the length of the central bore 1053 and a trans-
verse slot axtends radially from the bore 1053 to the outer
circumference of the cylindrical portion, providing flexibil-
ity to the cylindrical portion for clamping the nose member
to ths anvil. A flat i8 provided on one side of cylindrical
portion 1018 and longitudinally spaced holes are drilled
therethrough in alignment with threaded bores on the other
sida. Scrsw6 1059 are receiv~d in the hol0s and bores 1058
and tightened to secura nose member 1018 to anvil 1033.
The sidewall of the nose membsr 1018 extends forward
from the cylindrical portion 1052 and one side is milled to
form a flat inclined surface 1060 which tapers to a point at
- 85 -
~S5~S~
the extended end. The length and degree of inclination ma~
vary depending upon the particular application. The nosa
member 1018 may optionally have a flat rectangular fin 1061
(shown in dotted line) secured to the sidewall of ths cylin-
drical portion 1052 to extend substantially the length there-
of and radially outward thsrefrom in a radially opposed posi-
tion to the inclined surface 1060.
Slanted nose members 1018 of 2-1/2" and 3-1/2" d$a-
meter with an~les from 10 to 40 (as indicated b~ an~le "A")
have baen tested and show the nose member to be highly eff-
ective in turning the tool with a minimum turning radius of
28 feet bein~ achiaved with a 3-1/2 inch 15 nose member.
Testing also demonstrated that the turning effect of the nose
member wa~ highly repeatable with deviations among tests of
any nose member seldom varying by more than a few inches in
35 feet o~ bore. Additionally, the slanted nose members were
shown to have no adverse effect on penetration rate and in
some cases, actually increased it.
It has also been found that the turning radius varies
linearly with the angle of inclination. For a given nosa
angle, thc turning radius will decrease in direct proportion
to an increase in area.
The rear sleeve 1022 is mounted on the rear portion
of housing 1028 on bearings 1025 for rotary motion thereon.
The front sleeve 1021 and rear sleeve 1022 provide a 2-point
sliding contact on movement of the tool through the hole
- 86 -
l~iS6~i~
which ls being bored. Thi3 providcs for reduced friction and
facilitates both the linear movement of the tool through ths
soil and on rotation of th0 tool by tha fins. A tail fin
as6ambly 1062 (19a in Fig. 42) is secured in the bacX end of
the body 1028 (Fig. 47C). A fixed~lockable tail fin assembly
1062 is illustrated in the e~ample and other variation6 will
b0 describad hereinafter.
The tail fin assembly 1062 comprise6 a cylindrical
connecting sub 1063 having external threads 1064 at ths front
end whlch are raceived within the internal threads 1032 at
the back end of the body 1028. Sub 1063 has a short reduced
outside diameter portion 1065 forming a shoulder 1066 there-
between and a second reduced diameter 1067 ad;acent the short
portion 1065 forms a second shoulder 1068. An 0-ring seal
1069 i6 located on the reduced diameter 1065 intermediate the
shoulder6 1066 and 1068. The rear portion 1070 of the sub
1063 is smaller in diameter than the second reduced diameter
1067 forming a third shoulder 1071 thcrebetween and providad
with circumferential 0-ring seal 1072 and internal 0-ring
seal 1073. Internal threàds 1074 are provided in the rear
portion 1070 inwardly of the saal 1073. A circumferential
bushing 1075 of suitable bearing material such as bronzc is
provided on the second reduced diameter 1067.
A serias of longitudinal circumferentially spaced
grooves or keyways 1076 are formed on the circumferenca of
the rear portion 1070 of the sub 1063. A hollow cylindrical
- 87 -
~2S565i
piston 107~ is slidably received on the circumferencs of the
rear portion 1070 A series of longitudinal circumfersntial-
ly spaced grooves or keyways 1078 are formed on the interior
surface at the front portion of the piston 1077 in opposed
relation to the sub keyways 1076. A series of keys or dowal
pins 1079 are raceivad within the keyways 1076 and 1078 to
prevent rotary motion between sub 1063 and piston 1077.
A first internal cavity 1080 extends inwardly from
the keyway 1078 terminating ~n a short reduced diameter por-
tion 1081 which forms a shoulder 1082 therebetween. A sacond
cavity 1083 extends inwardly from tha back end 1084 of the
piston 1077 tarminating at the reduced diameter pcrtion 1081.
An internal annular 0-ring seal 1086 is provided on the re-
duced diameter portion 1081. As shown in Fig. 47C, a series
of drive teeth 1086 are formed on the back end of the piston
1077. The teeth 1086 comprise a series of circumferentially
spaced raised surfaces 1087 having a straight side and an
angularly sloping side forming a ratchet. A spring 1090 is
received within the first cavity 1080 of the piston 1077 and
is compressed between the back end 1070 of the sub 1063 &nd
the shoulder 1082 of the piston 1077 to urge the piston out-
wardly from the sub.
An elongated, hollow cylindrical rotating fin sleeve
1091 iæ slidably and rotatably received on tha outer peri-
phery of ths sub 1063. The fin sleeve 1091 has a central
longitudinal bore 1092 and a short counterbore 1093 of larger
- 88 -
~LZSS6S~
diameter sxtending inwardly from the front end and defining
an annular shoulder 1094 therebetween. The countsrbors 1093
fits over the short reduced diameter 1065 of the sub 1063
with the 0-ring 106~ providing a rotary seal therebetween. A
flat annular bushing 1095 of suitable bearing material such
as bronze is disposed bitween the shoulders 1068 and 1094 to
reduce friction therebetween.
A hollow cylindrical sleeve 1097 is secured within
sleeve 1091 by suitable means such as welding. The sleeve
1097 ha a central bore 1098 substantially the same diameter
as the second cavity 1083 of the piston 10~ and a counter-
bore 1099 sxtending inwardly from the back end deii~ing a
shouldflr 1100 therebetween. As shown in Fig. 47C, a series
of drive teeth 1101 are formed on the front end of the sleave
1097. The teeth 1101 oomprise a series of circumferentially
spaced raised surfaces 1102 having a straight side and an
angularly sloping side forming a one-way ratchet configura-
tion. The teeth correspond in opposed relationship to the
teeth 1086 of the piston 107~ for operative engagement there-
With~
A series of flat radially and angularly opposed fins
1105 are sscured to the exterior of the fin sleeve 1091 to
extend radially outward therefrom. (Fig. 4~C) The fins 1105
ar~ secured at opposing angles rclative to the longitudinal
axis of the sleeve 1091 to impart a rotational force on the
sleeve.
- 89 -
~5S~
An elongated hollow cap sleave 110 having sxternal
thr0ads 110~ at the front end is slidably recelved within the
sliding piston 107r and the sleeve 109~ and threadedly ~ecur-
ed in the internal threads 1074 at the rear portion 1070 o~
th0 sub 1063. The cap sleeve 1;06 extends rearwardly from
the threads 110~ and an enlarged diameter portion 1108 forms
a ~irst shoulder 1109 spaced from the threaded portion and a
second enlargsd diameter 110 ~orms a second shoulder 1111
spac~d from the first shoulder. An 0-ring seal 1112 is pro-
vided on anlarged diameter 1108 nsar shoulder 1109 and a
second 0-ring seal 1113 is provided on the second enlarged
diameter 1110 near the second shoulder 1111. The 0-ring 1112
forms a reciprocating seal on the interior of the sacond
cavity 1083 of the piston 1077 and the 0-ring 113 forms a
rotary seal on the counterbore 1099 of the sl3eve 1097. The
0-ring 1085 in the piston 1077 forms a reciprocating seal on
the extended sidewall of the cap 1106.
An annular chamber 1114 is formad between the exter-
ior oY the sidewall of the cap 1106 and the second counter-
bor0 1083 which is sealed at each end by the 0-rings 1085 and
112. A circumferential bushing 115 is provided on the first
enlarged diameter 1108 and an annular bushing 116 on the sec-
ond enlarged diameter 110 is captured betwaen the shoulders
1100 and 1111 to reduce friction between the sleeve 1097 and
the cap 1106. The rear portion of the cap 1106 ha~ small
bores 111~ arranged to recaive a spanner wrench for effacting
-- 90 --
~2~56~i~
the threaded conneation. A threaded bore 1118 at the back
snd of cap 1106 receives a hose fitting (not shown) and mall
passageway 1119 extends inwardly from threaded bore 1118 to
communicate annular chamber 1114 with a fluid or air source
(not shown). A flexible hose extends outwardly of the cap
1106 and i8 connected to the fluid or air source for effect-
ing reciprocation of the piston 1077. A second small passage-
way 1120 communicates first cavity 1080 with atmosphere to
relieve pressure which might otherwise become trapped thers-
in. Pa~sage 120 may also be used for application o~ pressureto the ~orward end of piston 1077 for return movemcnt.
OPERATION
The tool described abova is capable of horizontal
guidance, has overgage body sections, and is preferably used
with a magnetic field attitude sensing system. The boring
tool may be used with various sensing systems, and a magnetic
attitude sensing system i8 dep~cted generally as one example.
The overgage sleeves may be fixed or rotatable on bearings as
described above. Likewise, the overgage sleeves may be used
with any percussion boring tool of this general type and ia
not limited to the particular guidance arrangement, i.e., the
slanted nose member and controllable tail fins, described
above. It is especlally noted that any of the arrangements
described in our copending patent application can be used
with overgage sleeves to obtain the desired advantages.
- 91 -
~S~5~
The procedure for using this psrcussion tool is to
first locate and prepare th0 launching and retrieval pits.
As de6cribed above, the launching pit P is dug slightly deep-
er than the planned boring depth and large enough to proride
sufficient movement for the operator. The boring tool 1010
is connected to a pneumatic or hydraulic source 11, i8 then
startsd in tha 60il, stopped and properly aligned, preferably
w~ith a sighting frame and level. The tool is than restarted
and boring continued until the tool axits into ths retrieval
pit (not shown).
The tool can move in a straight directlon when used
with an eccentric boring force, a.g., the slantsd nose member
or the eccentric hammer or anvil, provided that the fins are
positioned to cause the tool the rotate about its longitudin-
al axis. When the fins are aet to allow the tool to movewithout rotation about the longitudinal axis, the eccentric
boring forces cause it to move either at an angle or along an
arcuate path.
As previously described, the overgage sleeves, which
are located over a portion o~ the tool outer ~urface, are
affixed such that they can rotate but cannot slida axially.
This permits transmittal of the axial impact force from the
tool to the soil while allowing free rotation of the tool
during spinning operations. The overgage areas are at tha
front and back of the tool, or alternataly, an undergage
section in the center of the tool body. This undercut in
_ 9~ _
~2~S6~
the csnter of the tool permits a 2-point contact (front and
rear) of the tool's outer housing with the soil wall as op-
posed to the line contact which occurs without the undercut.
The 2-point contact allows the tool to dsviata in an arc
withouk distorting the round cross-sectional profile of the
pierced hole. Thus, for a given stearing force at the front
and/or back of the tool, a higher rats of turning is possible
since a smaller volume of 80il needs to be displaced.
In the embodiment shown, for turning the tool t the
tail fins 1017 are moved into a position where they may spin
about the longitudinal axis of the tool 1010 and the slanted
nose member 1018 or eccentric hammer will deflect the tool in
a given direction. When the fins 1017 are moved to a posi-
tion causlng the tool 1010 to rotate about its longitudinal
axis, the rotation will negate the turning effect of the nose
member 1018 or eccentric hammer as well as provide the means
for orientlng the nose piece into any given plane for subse-
quont turnlng or dircction change.
The front 1021 and rear 1022 overgag~ body sections
give improved performance of the tool both in straight boring
and in angular or arcuate boring. These overgage sections
are $ixed longitudinally on the tool body and may be fixed
against rotation or may be mounted on bearings which permit
them to rotate.
Whils the overgags sleeves can be used with any per-
cussion boring tool, they have been shown in aombination with
- 93 -
~2S5~
one the embodiments described abov0. The operation of this
percussion boring tool 1027 is as follows. Under action of
compressed alr or hydraulic fluid in the central cavity 1041,
the hammer 1037 moves toward the front of the body 1028. At
the foremost position, the hammer imparts an impact on the
flat surface 1036 of the anvil 1033.
In thi~ position, compressed air i8 admitted through
the passages 1044 from central cavity 1041 into ths annular
cavity 1039. Since the effective area of the hamm~r includ-
ing the larger diameter rear portion 1040 i6 greatsr than the
effective area of the central cavity 1041, the hammsr starts
moving in the opposite direction. During this movement, the
bushing 1042 closes the passage6 1044, thereby interrupting
the admission of compressed air into annular cavity 1041.
The hammer 1037 continues its movement by the expanR-
ion of the air in the annular cavity 1039 until the passages
1044 are displaced beyond ths ends of the bushing 1042, and
the annular cavity exhaust~ to atmosphere through the holes
10~0 in the stop member 1049. Then the cycle is repeated.
The operation of the tail fin as6embly 1062 is best
saen with reference to Fig. 47C. The compressed air or fluid
in the annular cavity 1114 movas the piston 1077 against the
spring 1090 and toward the front of the sub 1063. In the
foremost position, the front end of the piston 1077 contacts
the Rhoulder 1071 and the drive teeth 1086 and 10101 become
- 94 -
~;~S5~5~
disengaged. In this position, compressed air or ~luia i8
admitted through the passage 1119 from the source lnto the
annular chamber 1114. The fin sleeve 1091 is then free to
rotate relative to the tool body. Pressure which may other-
wise become trapped in the first cavity 1080 and hinder re-
ciprocation is exhausted through the pressura ralief passage
1120 to atmosphero.
When the air or fluid pressure within ths chamber
1114 is relieved, the force of the spring 1090 moves the pis-
ton 10~ in the opposite direction. During this movement,the drive teeth 1086 and 1101 become engaged once again and
the fin sleeve 1091 becomes locked against rotational movem-
ent relative to the tool body. The cycle may be selectively
repeated as necessary for proper alignment the slanted nose
member 1018 and attitude adjustment of the tool. It should
be understood that the passage 1120 may also be connected to
a fluid source, i.e. liquid or air, for moving the piston to
the rearward position.
The reciprocal action of the hammer on the anvil and
nose member as previously described produces an eccentric or
asymmetric boring force which causes the tool to move forward
through the earth along a path which deviates at an angle or
along an arcuate path when the tool i8 not rotating. Whe~
the tool is rotated by operation of the fins, it movss along
a substantially straight path (actually a very tight spiral).
Th~ overgage sleeves support the tool housing at two separ-
- 95 -
~2~565~
at0d points. This 2-point contact ~front and rear) of the
tool housing with the 80il wall allows the tool to dsviats
in an arc without distorting the round cross-sectional pro-
file of the pi~rced hole. Thus, for a given steering force
at the front and/or back of the tool, a higher rat0 of turn-
ing is possible since a smaller volume of 60il needs to be
displaced and the helix length is reduced.
DESCRIPTION 0~ T~E CONTROL SYSTEM
This embodiment relate~ to the control of the guid-
ancs of a percussion boring tool, especially using a magneticsensing system or sensing tool location and attitude.
In the installation of conduits and pipes by various
utilities, such as gas, telephone and electric utilities, a
problem often faced i6 th~ n0ed to install or replace such
conduits or pipes under driveways, roads, streets, ditches
and/or other structures. To avoid unnecessary excavation and
repair of structur0s, th0 utilities use horizontal boring
tools to form the bor0 holes in which to install the conduits
or pipes. 3uch tools hav0 been unsatisfactory to the extent
that th0ir traverse has not been accurate or controllable.
All to frequently other underground utilities hav~ been
pierced or the ob;ective target ha~ been mi6sed by a substan-
tial margin. It has aso be0n difficult to st0er around ob-
stacles and get back on course.
In ~ig. 48 is illustrated horizontal boring operatior.
in which a borehole 1~10 is being bored through the earth
- 96 -
56~
1212 under a roadway 1214 by a horizontal boring tool 1216.
Th0 particular tool illustrated and for which the pre~erred
embodiment of the present invention was specifically de~igned
is a pneumatic percussion tool, operated like a Jackhammer by
a motive m0chanism 1217 using compre6sed air suppliad by a
compressor 1218 by way of an air tank 1219 over a supply hose
1220. Ths tool 1216 is elongated and has a tool axis 1222
extending in the direction of its length. Ths lead end of
th~ tool 1216 has a piercing point (or edge) 1224 eccentric
of he axis 1222. The operation of the percussion tool drives
the point 1224 through the earth, advancing the tool forward,
but slightly off axi6.
The tool 1216 includes a plurality of staering vanes
1226 which may be aotuated by pneumatic or hydraulic control
anargy provided over pneumatic or hydraulic control lines
1228 from a controller 1230 to control the direction and rate
rotation of he tool 1216 about its axis. Control signals may
also control the operation of the motive mechanism 1217. The
controller 1230 is supplied wi~h air from the compressor
1218 over a bore 1232.
The steering vanes 1226 my be turned to cause the
tool to rotate at a relatively constant rate. The tool then
spirals a bit but advances in a substantially straight line
in the direction of the axis 1222 because the piercing point
1224 circles the axi6 and causes the tool to deviate the same
amount in each direction, averaging zero. If the vanes 1226
- 97 -
S6S~
are returned to directions parallel to tha axis 1222, the
rotation may be stopped with the tool in a desired position,
from which it advanoes asymmetrically in a desired dlrsction.
As will be described below, the pre6ent invention
permits an operator to identify the rotatonal orientation of
the tool 1216 about its axis 1222, and, hence, to direct the
advance o~ the tool. Thc ob;ective i8 to bore a hola 1210
relatively horizontally between an input pit 1234 and a tar-
get pit 1236 beneath such obstacles as ths roadway 1214.
10The hole 1210 must avoid piercing other utility lines 1238 or
sewers 1240 or other buried obstacles. Thesa may be identi-
fiad and located from historical æurveyor's drawings or may
be located by 60ms other means as by a metal detector or
other proximity device 1242.
15Armed with this information, an operator may 6tart
the tool off easily enough from the input pit 1236 in a dir-
ection that avoids nearby obstacles and may plot a couræe
that would miss all mor0 distant obstacles. Thedifficulty is
in assuring that the tool follows the plotted course. That
is the function of the present invention. The present in-
vention is directed to a control system for sensing the atti-
tude of the tool 1216 and for controlling the steering vanes
1226 to direct the tool along the plotted course. The con-
trol system includes an electromagnetic source 1244 affixed
to the tool 1~16 for generating appropriate alternating mag-
netic flux, a senslng aæsembly 1246 disposed in ons of the
- 98 -
S~
pits 1234, 1236, preferably the target pit 1236, and circuit-
ry in the controller 1230 which is powered from a motor-gen-
erator set 1248.
Reference may be made to Fig. 49 for an understand$ng
of the prsferred arrangement of the electromagnetic source
1244 and the sensing assembly 1246. The electromagnetic
source 1244 comprise6 an axial coil 1250 and a tran3verse
ooil 1251 rigidly mounted on the tool 1216. The coil~ 12~0
and 1251 are alternatively energized from the motor-generator
power source 1248 through a controlled power supply 6ection
1252 of the controller 1230 over lines 1253. The power
source 1248 operates at a relatively low frequency, for ex-
ample, 1220 ~z.
The axial coil 1250 generates an axial alternatlng
magnetic field which produce~ lines of magnetic flux general-
ly symmetricall~ about the axis 1222 of the tool 1216, as
illustrated in ~ig. 50. The tool 1216 itself is constructed
in such manner as to be ¢ompatible with the generation of
such magnetic field and, indeed, to shape it appropriately.
The transverse coil 1251 generates a transaxial alternating
magnetic field substantially orthogonal to th0 axis 1222 in
fixed relation to the diraction o~ deviation of the point
1224 from the axis 1222 and, hence, indicative of the direct-
ion thereof.
The eensing assembly 1246 is formed o~ three orthog-
onal pickup coils 1254, 1256 and 1258, as shown in Figs. 49
_ 99 _
s~
and 51, which may be called the X, Y and Z coils, respectiv-
ely. These pickup coila are axially sensitive and can be of
the box or solenoidal forms shown in Figs. 49 and 51. The
center of the coils may be taken as the origin of a thrss-
dim0nsional coordinate syst0m of coordinate Rystem of ¢oord-
inates x, y, ~, where x is the general direction oi' the bore-
hole, y i8 vertical and 7~ i5 horizontal. The coils 1254,
1256 and 1258 have respective axes extending from the origin
of the coordinate ystem in the respective x, y and z direct-
10 i ons .
In Figs. 50A, 50B, 50C and 50D are illustrated fourpossible unique relationships of a sensing coil, the Y coil
1256 as an example, to the lines of flux 60 of the axial
magnetic field generated by the axial coil 1250 in the tool
1216. In Fig. 50A is shown the relationship when the X axis
and the tool axis 1222 lie in the same plane with the Y axi6
of he coil 12B6 normal to that plane. That is the relation-
ship when the tool 1216 lies on the plane XZ (the plane per-
pendicular to the Y axis at the X axis) with the axis 1222 of
the tool in that plane. In Fig. 50B is shown the relation-
ship when the tool 1216 lies in the plane XZ with the tool
axis 1222 not in that plane. That is the relationship when
the tool 1216 is tilted up or down (up, clockwise, in the ex-
ample illustrated). In Fig. 50C is shown the relationship
when the tool 1216 is displaoed up or down from the plane gZ
(up, in the example illustrated) with the tool axis 1222
- 100 -
6S~
parallel to the plane XZ. Other relationships involve com-
binations of the relationships shown in Figs. 50B and 50C;
that is, where the tool 1216 lies o$f the XZ plane and has a
component of motion transvers01y thereof. Shown in Fig. 50D
is the ralationship where the combination of displacement
(Fig. 50C) and tilting (Fig. 50B) places tha coil axis Y
normal to the lines of flux 1260 at the coil. The lines of
flux shown in Figs. 50A, 50~, 50C and 50D are for condition6
when tool axis 12a2 lines in the XY plans (containing the X
and Y axes), but the principle is the same when the tool lie6
out of such plana. The lines of flux linking Y coil 1256
would be different, and the relativs signals would be some-
what differant. There would, however, still be positions of
null similar to those illustrated by Figs. 50A and 50D.
As can be seen by inspection and from ths principle
of symmetry, the pickup coil 1256 will generate no signal
under the condition shown in Fig. 50A because no flux links
the coll. On the othar hand, under the conditions of Figs.
50~ and 50C, signals will be generated, of phase dependent
upon which direction the magnetic field is tilted or displac-
ed from the condition shown in ~ig. 50A. Further, under the
condition shown in Fig. 50D, the effect of displacement in
one direction is exactly offset by tilting so as to generata
no signal. As may also be seen from Fig. 50D, if the tool
1216 is off course (off the XZ plane) but the relationship
shown in Fig. 50D is maintained, the tool will move toward
-- 101 --
3~;25~6S~
the sensing assembly 1246 keeping the sensing assembly on æ
given line of flux 1260. That is, the tool 1216 will home in
on the sensing assembly 1246 and get back on course vertical-
ly. Similar relationships exist in respect to the Z coil
1258 and horizontal deviation. The outputs of the pickup
colls 1256, 1258 are applied through a 8 ignal conditioner
1262 to a display 1264 in the controller 1230.
Tha ralationships shown in ~ig. 50 can also be anal-
yzed geom3trically as shown in Fig. 50, where A is the angle
between the tool axis 1222 and a line 1265 connecting the
center of ths tool with the center of the pickup co~l 1256,
and ~ is the angle between the line 1265 and the refsrence
axis X, perpendicular to khe axis Y of the sensing coil 1256.
The well known equation for radial flux density ~R
and angular flux density BA are:
B~ = 122 Kl cos A (1)
BA - Kl sin A (2)
where Kl is a con~tant proportional to the amper~-turns for
the axial coil 1250 and inversely proportional to the cube of
th distance between the tool 1216 and the sensing coil 1256.
The singal V thereupon developed in the pickup coil 1256 is
proportional to the sum of flux components parallel to the
coil axis Y.
That is, V = K2 (BR sin B + BA cos B) ~3)
where K2 is a calibration factor betwaen the developed pick-
up voltag0 and time-rate-of-change of the magnetic field.
- 102 -
lZS56S~
~rom the combination of Equations (1), (2) and (3~:
V = K3 (2 cos A sin ~ ~ A cos B) (4)
when K3= KlK2. As i~ flvident from ~ig. 50D, when tha flu~ at
the coil 1266 is normal to its axis Y, the two componsn~s
balance, i. e., ~R sin ~ = -BA C08 B, making V = 0.
The circuitry for operating the present invention is
shown in greater detail in ~ig. 51 in block diagram form. ~s
there shown, the output of the pickup coil 1256 i6 amplified
by an amplifiar 1266 and applied to a synchronoua detector
1268 to which the output of a regulated powar supply 1270 is
also applied. The regulated power supply 1270 is driven by
the same controlled power supply 1252 that drives the coils
1250, 1251 and producas an a.c. voltage of constant amplitude
in fixed phase relationship to the voltage applied to the ax-
ial coil 1250.
The synchronous detector 1268 therefore produces a
d.c. output of magnitude proportional to the output of the Y
coil 12B6 and of polarity indicative of phase relative to
that of the power supply 1270. An amplifier 1272 and a syn-
chronous detector 1274 produce a similar d. c. output corres-
ponding to the output of the Z coil 1258. Tha outputs of ths
raspactive synchronous datectors 1268 and 1274 ara appliad to
ths display 1264 which displays in y, z coordi-natas the
combination of the two signals. This indicates the dirsction
or attitude the tool is off course, permitting the operator
to provida control signals over the control lines 1228 to
- 103 -
~zs~s~
return the tool to its proper course or to modify the courss
to avoid obstaclss, as the case may be.
The ext0nt to which the tool iB off a course leading
to the target is indicated by the magnituds of the signals
produced in the coils 1256 and 1258. However, the magnitude
of the respective signal6 is also affectsd by the range of
the tool. That is, the farther away the tool, the lesser the
flux denaity and, henc~, the les6er the signals gensrated in
the respe¢tive pickup coils 1256 and 1258 for a given daviat-
ion. It i8 h0 function of the X coil 12B4 to ramove this
variable. The X coil is se~sitive to axial flux density sub-
st,antially ex¢lusively. The y and z directed ~lux oomponents
have negligible effect on its output where the tool 1216 li0s
within a few d0grees of the x direction; e.g., 123.
The signal from the pickup coil 1254 is amplified by
an amplifier 1276 and detected by a synchronous detector 1278
to provida a d. c. output proportional to the flux density
strength at the X coil 1254. This signal i9 applied to 3
control circuit 128~ which provides a field aurrent control
for the power supply 1252. This provides feedback to change
the pow0r applied to tha axial coil 1250 in such dirsction as
to maintain constant the output of the ~ coil 1254.
Thi6 makes the flux density at the sensing assembly
1246 relatively constant, thus normali7.ing the outputs o~ the
Y and Z coils 1256, 1258 and making these outputs relatively
independent of range. However, if wide deviations from dir-
- 104 -
~5S~S~
ect paths between tha launch and e~it polnts are sxp3cted,
the total magnitude of the magnetic flux density should b9
used for this normalizing function. This magnitude may be
developad by appropriately combinlng tha outputs from the
three pickup coils.
It is one thing to know where the tool iB and it~
attitude. It is anothsr to return it to its course. That i8
the function of the transversa coil 1251. Tha power from the
power supply 1252 is appliad to the tool 1216 through a
switch 1282.
~ hen in the 6witch 1282 position 121, the axial coil
1250 is ener~ized, providing the mode of operation explained
above. With the switch 1282 in position 122, the transverse
coil 1261 is energized instead. The resulting magnetic field
is substantially orthogonal to that provided by the a~ial
coil 1250. The signals generated by the Y and Z pickup coils
1256, 1258 then depend primarily upon the relative displace-
ment of th0 coil 1251 around the axis 1222.
~ecause the coil 1251 is mounted in fixed relation-
ship to the piercing point 1224, ths displacement of the
point is indicated by the relative magnitude of the respect-
ive signals from the respective Y and Z coils as detected by
the respactive synchronous detectors 1268 and 12~4 and,
hence, is indicated on the display 1264.
This enables the operator to position the tool 1216
about its axis by controllinbg the po~ition of the vanes 26
- 105 -
~?s~?~s~
and thereby cause the tool 1216 to advance in desirea direct-
ion relative to i9 axis 1222. The i'eedback by way of the
controller circuit 1280 is not used in this mode, as ths sig-
nal from ths X coil 1254 is near zero in this mode.
The present invention is useful in a simple form when
it is deslrable simply to keep the tool on a straight course.
This is achieved simply by directing the tool 1216 toward the
sensing assembly 1246 while kseping th0 outputs picked up by
the Y and Z coils 1256, 1258 nulled. As mentioned above, it
i9 possible to deviate to avoid obstacles and then return to
the course.
Thls is facilitated by keeping track of where the
tool is at all times. This requires measurement of the tool
advance. within the borehole. Although this is indicated to a
degree by the power required to maintaln constant the output
of the X coil 1254, it i5 more accurate to measure x dis-
placement along the borehole more directly by measuring the
length of lines 1253 fed into the borehole or by a distance
indicating potentionmeter 1284 tied to the tool 1216 by a
llne 1286. This provides a signal on a llne 1288 indicating
displacement and incremental displacement of ths tool 1216
within the borehole. This information, in combination with
the signal6 from Y and Z coils 1266, 1258 permits the opera-
tor to keep track of the location of the tool at all times.
When distance is kept track of and position is deter-
mined, it iB possible by more sophisticated electronics to
- 106 -
~2S~
operate with the sensing ass0mbly in the input pit 1234,
particularly if the tool 1216 kept substantially on the x
~xis. For example, if the tool is allowed to progress a
substantial distance from the desired axis, the angla B be-
comes significant and a more complicated set of relationshipsapply than when the siza of the angle B is near O and its
cosine 121. That is, Equation (4~ may not be simply approx-
imated.
In this case, it will be necessary to continuously
develop the position of the tool in ordsr to provide accurate
data on its location. In this case, the initial tool orien-
tation is determined by means of the sensor coils. Then the
tool i8 allowed to advance an incremental di6tance, which is
also measured. The new locatioll is then determined based on
the initial angle and the in¢remental amount of progress, and
integration process. This process is continuously repeated
$or continuous determination of the position of tha tool.
Other modi$ications of tha present invention are also
possible. For example, the sensing assembly 1246 may be
moved from place to placa or its orientation charged during
boring in order to change course. Also the sensor coils can
be located on tha tool and the source coils can be located on
the tool and the source coils placed in either pit. It is
also within the scope of the present invantion to provide
sensors on the tool 1216 for sensing obstaclas, hence permit-
-- 10~ --
~;25S6~;1
ting control of tha direction of tool advance to avoid th~obstacles.
Other types of boring or drilling systems can ba used
in conjunction with the present invention, such as hydraulic
peroussion tools, turbo-drill motors (pneumatic or hydraulic)
or rotary-drill typ0 tools. The important aspects of the
tool are that it include some motivs means and a stsering
mechanism that can be controlled by control signala ~rom
afar.
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