Note: Descriptions are shown in the official language in which they were submitted.
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FASTENER SYSTEM INCLUDING A
SWAGE FASTENER AND TOOL FOR INSTALLING SAME
SUMMARY BACKGROUND OF THE INVENTION
The present invention relates to a fastener
system for multi-piece swage type fasteners, methods of
installation and a tool for installing such fasteners.
The present invention relates to two-piece swage
type fasteners or lockbolts generally of the type
illustrated in U.S. Patent Nos. 2,531,048 and 2,531,049 to
L. Huck both.~issued on November 21, 1950, and in U.S.
Patent No. 3,915,053 to J. Ruhl, issued October 28, 1975.
Swage type fasteners of the type noted are
freguently of a two-piece construction comprising a pin and
a collar adapted to be swaged into locking grooves on the
pin. The fasteners shown in the referenced '048 and '049
patents are pull type swage fasteners while those shown in
the '053 patent include both pull type and stump type
versions of swage fasteners. In the typical pull type
fastener, the: pin is provided with an enlarged head and a
pin shank having locking grooves in a lock groove portion;
the pin shank terminates in a pintail portion constructed
with pull grooves adapted to be gripped by a jaw assembly
of an installation tool. A swage anvil is provided on the
tool to engaige and swage the collar into the locking
grooves. A relative axial force is applied between the pin
and collar, ;end hence between workpieces to be fastened
together, as the tool pulls on the pin via the pintail
portion with the force being reacted by the engagement of
the swage anvil with the collar. This relative axial force
pulls the workpieces together under an initial clamp load.
As the relative axial load increases the swage
anvil moves axially to radially overengage the collar,
swaging it into the locking grooves, whereby the pin and
collar are locked together and the final clamp load on the
workpieces is developed. The swage anvil has a swage
cavity which :receives the collar circumferentially for 360°
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and axially aver the majority of the length of the collar
or collar shank where a flanged collar is employed whereby
a substantia7_ portion of the swageable collar material is
deformed into the locking grooves of the pin, generally
uniformly around its circumference.
The pintail portion is connected to the locking
groove portion by a breakneck groove which is constructed
to break at a preselected axial load after the swaging step
has been completed whereby the pintail portion is severed
and discarded.
In the stump type version, the lockbolt is set
by a squeeze type tool which has a stationary member at one
end of the workpieces for engaging the pin head and a swage
anvil at the opposite end for engaging the collar. The
fastener is set as the anvil moves axially against and
radially over the collar with the axial force being reacted
by the engagement of the stationary member with the pin
head. Thus the stump type fastener has the advantage of a
shorter pin shank since the pintail portion with pull
grooves and breakneck groove is not required. Because of
the latter t:he stump version has the advantage of being
lighter and of a lower cost.
Bu.t there are other advantages of the stump type
swage fastener relative to the pull type fastener. With
the pull type fastener, the severed pintail portion creates
debris in the' work area requiring periodic collection and
disposal. Also the stump version will assure a smooth,
finished end at the pin shank whereas the pull type pin
shank will occasionally have a rough surface from the break
at the breakneck groove. Finally the noise occasioned by
pinbreak is absent in the stump type fastener.
There are, however, numerous applications in
which a stump type fastener cannot be used or it is not
expedient to do so. One example is an assembly in which
there is insufficient clearance on the pin head side of the
workpieces to permit access for the related stationary
portion of the squeeze tool. Another example is an
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assembly having insufficient clearance to permit insertion
of the longer pull type pin into the mating openings of the
workpieces. The present invention addresses such problems.
Thus with the present invention a unique fastening system
including a awage type fastener and installation tool is
provided for a pull type installation but, as will be seen,
having advantages of a stump type fastener and
installation. Indeed, where both squeeze type and
installation type applications and apparatus are present,
the fastener of the present invention can be installed in
either fashion resulting in a reduction in overall
inventory and in the numbers of different parts to be
stocked.
Thus the present invention is of a swage type
fastener with a pin having a shank constructed without a
severable pintail portion but terminating in a short,
threaded pull portion of minimal length. A unique tool is
shown which functions to provide a pull type installation;
the tool includes a threaded, hardened nut member adapted
to threadably engage the short pull portion via rotation by
a rotary drive motor. Once a sufficient number of threads
have been engaged or gripped by the nut member, the pull
tool is actuated to apply a relative axial force by pulling
on the pin, through the nut member, with a swage anvil
engaging the collar to react the pulling force. At this
juncture, the fastening system performs similarly to a pull
type installation system. Thus as the magnitude of the
relative axial force increases the workpieces being secured
are pulled and clamped together under a desired preload.
Upon further increases in the axial force the anvil will be
moved axially to radially overengage the collar and swage
it radially into the locking grooves on the pin shank
providing the' final clamp load. Next the direction of
relative axial force between the swage anvil and nut member
is reversed moving the swage anvil in the opposite axial
direction to 'thereby eject the swaged collar. Finally, the
hardened nut member is reverse rotated from the short,
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threaded pull portion removing the installation tool and
completing tree installation. A rotary drive motor in the
pull tool is used to thread the nut member onto and off
from the threaded pull portion. Thus no pintail portion is
required to he removed after swage and hence there is no
related debris. In addition the installation is quieter
since pinbreak noise is eliminated. The length of pin
shank comprising the short, threaded pull portion is
minimal, i.e. around four threads, such that only a small
difference in length of pin shank remains relative to a
comparable stump type pin set by a squeeze tool and/or the
pin shank of a pull type fastener after the pintail portion
has been removed by a conventional pull type tool.
In one form of the invention the lock grooves
and threads of the pull portion of the pin are in the form
of a continuous helical male thread. The collar is
provided with a mating, female thread of a preselected
extent such that an initial clamp of the workpieces can be
accommodated. However, the female collar thread is
selected to be of a limited circumferential extent and
shear strength such that, in response to the relative axial
force and at a level prior to the initiation of collar
deformation into the lock grooves of the pin, it will shear
or deform; in this condition the collar will be generally
free to move axially over the pin and to respond to the
installation loads in the same manner as a collar without
such limited female thread form.
The preceding fastener structure with limited
threaded collar is sometimes referred to as a "fit-up
fastener" and is shown and described in the U.S. Patent No.
4,867,625 issued September 19, 1989 to R. Dixon for
"Variable Clamp Fastener and Method"; that structure,
however can be considered as prior art to the present
invention. Cane advantage of the fit-up fastener structure
in a combination in the present invention is that the
workpieces
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can be initially pulled together to remove gap thereby
providing greater certainty that a sufficient number of the
threads of the pull portion will extend beyond the collar
and be accessible for gripping by the nut member.
Alternatively, a collar with a flexible tab can
be used for fit-up; such a structure is shown in the United
States Patent No. 4,813,834 for "Fit-Up Fastener With
Flexible Tab-Like Structure and Method of Making Same"
issued March 21, 1989 to Walter J. Smith.
In a preferred form of the invention, the tool
nut member i.s designed simply to threadably engage and
thereby grip the minimum length pull portion of the pin;
thus, in this first step, the tool nut member is not moved
against the collar with any significant force and hence is
not used to pull the workpieces together and/or clamp them
under an initial preload. After the threaded engagement
step, the installation tool is actuated to cause the swage
anvil to move axially against the collar in response to a
relative axial force applied between the nut member and the
anvil. Thu:~ the initial clamp up and preload of the
workpieces is substantially provided for the first time by
the relative axial force applied between the nut member as
engaged with the pull portion of the pin shank and the
engagement of the swage anvil with the collar. As
previously described, the relative axial force is increased
until the swage cavity of the anvil is moved axially to
radially overengage the collar swaging the collar material
into the pin. With this construction, the rotary drive
motor for the nut member simply provides the function of
threading the nut member on and off the short pull portion
of the pin shank and is not used to apply any significant
axial load to the workpieces. Thus the capacity of the
drive motor can be small permitting the overall size of the
installation tool to be minimized. In one form of the
invention, the engagement of the tool nut member on the
threaded pull portion is limited and the nut member
positioned thereon such that the collar, upon elongation in
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swage, will essentially not engage the nut member. Thus no
significant axial bearing load will be applied against the
nut member from collar elongation after swage; this
inhibits increases in friction between the engaged threads
of the nut member and pull portion which would result from
such bearing load. In this way removal torque can be
maintained law which also facilitates the use of a rotary
motor of minimal size.
Prior crimp type fasteners, while utilizing a
pintail-less or stump-like structure would not provide the
same advantages and/or ease of installation as the present
invention. For example, a threaded crimp type fastener
would not provide the same flexibility and ease of
installation and would require more complex installation
tools. In this regard see the U.S. Patent No. 3,421,562 to
J. Orloff et al issued on January 14, 1969. There a
threaded fastener nut or collar is first installed on a
threaded pin shank and torqued to provide initial pull
together and clamp up of the workpieces of a first
magnitude; th.e final clamp load is achieved by crimping a
smooth portic>n of the nut resulting in elongation of the
nut and an increase in clamp load to a desired final
magnitude. Thus in the system of the '562 patent the
fastener is not set as either a stump type or pull type as
described and is unlike the system and fastener of the
present invention. In this regard see also the U.S. Patent
No. 3,803,793 to W. Dahl issued on April 16, 1974.
Another crimp type fastener is shown in the U. S.
Patent No. 4,012,828 to W. Dahl issued March 22, 1977.
There a threaded mandrel on a tool is first threaded onto
a threaded pin shank until the mandrel engages a smooth
bored collar to clamp the workpieces together and to apply
an initial preload of a first magnitude. Next crimping
jaws, spaced radially about the collar, are actuated to
move radially inwardly to deform the material of the collar
into threads or locking grooves in the pin. The resultant
collar elongation reacts between the engaged workpiece and
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the engaged end of the threaded mandrel to provide an
increased clamp load of a final magnitude. After
disengaging t:he crimping jaws, the mandrel is threaded off
the pin to complete the installation. Thus, again, in the
system of the: '828 patent, the fastener is not set as the
stump or pull type fastener in the manner previously
described and. also is unlike the system and fastener of the
present invention. See also the U.S. Patent No. 3,920,338
issued to W. Dahl on November 18, 1975.
The U.S. Patent No. 3,025,730 issued to H.
Brilmyer et al on March 20, 1962 discloses the use of a
manual installation tool on a swage fastener having a
threaded pintail partion and a breakneck groove with a nut
on the tool threadably engageable with the pintail portion.
The system and fastener of the '730 patent is also unlike
the system and fastener of the present invention.
The U.S. Patent No. 4,299,519 issued to R.
Corbett on November 11, 1981 discloses a fastener with a
minimum length removable pintail portion; it also discloses
a pin having an internally engageable pull groove structure
and no removable pintail portion. That fastener, however,
does not di:~close the externally, threaded short pull
portion nor does it disclose an internally threaded
gripping portion.
As will be seen from the description of the
embodiments which follows, various combinations of fastener
pins and collars can be used with the system and
installation tool of the present invention. Thus it is an
object of the present invention to provide a unique
fastener system including novel swage type fasteners having
the advantages of a stump type fastener and being installed
generally as a pull. type fastener.
It is another object of the present invention to
provide a novel fastening system including a unique
installation tool for use in setting swage type fasteners.
It is another general object to provide a unique
fastening system including a novel swage type fastener and
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a novel installation tool.
Other objects, features, and advantages of the
present invention will become apparent from the subsequent
description and the appended claims, taken in conjunction
with the accompanying drawings, in which:
Figure 1 is an elevational view with some parts
shown broken away and others shown in section of a swage
type fastener including a pin and a collar and embodying
features of the present invention shown in relationship to
a portion of a tool of the present invention for installing
the fastener with the tool not yet applied to the fastener
for installing the fastener;
Figure 2 is a view, to reduced scale, of the
fastener and tool portion of Figure 1 shown after a nut
member of the tool portion has been initially threadably
applied to a threaded pull portion of the pin;
Figure 3 is a view, to reduced scale, of the
fastener and tool portion of Figure 1 shown after the
collar has been swaged via a swage anvil into locking
grooves on th.e pin;
Figure 4 is a view, to reduced scale, of the
fastener and tool portion of Figures 1-3 shown after the
swage anvil of the tool portion has ejected the swaged
collar but while the nut member of the tool portion is
still threadably engaged with the pull portion of the pin;
Figure 5 is an enlarged, fragmentary view of a
portion of an: installation tool, similar to that shown in
Figures 1-4, but with the tool nut member having a
different thread configuration;
Figure 6 is a view similar to Figure 1 but
depicting a modified swage type fastener having a pin of a
different form including a threaded pull portion and a
locking portion with annular locking grooves;
Figure 7 is a view similar to Figure 1 of a
swage type fastener and portion of a tool but depicting a
modified swage type fastener including a collar having a
partial thread to provide initial fit-up of the workpieces
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via engagement with a threaded pin;
Figure 8 is a view, to reduced scale, of the
fastener and tool portion of Figure 7 shown after a nut
member of the tool portion has been initially threadably
applied to a threaded pull portion of the pin;
Figure 9 is a view, to reduced scale, of the
fastener and tool portion of Figure 7 shown after the
collar has been swaged into locking grooves on the pin and
initial swaging or snubbing of the collar has occurred;
Figure 10 is a view, to reduced scale, of the
fastener and tool portion of Figures 7-9 shown after a
swage anvil of the tool portion has ejected the swaged
collar but while the nut member of the tool portion is
still threadably engaged with the pull portion of the pin;
Figure 11 is a fragmentary view to enlarged
scale depicting a pin with different thread forms for the
pull groove ~>ortion and the locking groove portion of the
pin;
Figure 12 is a fragmentary view to enlarged
scale depicting a pin with still another combination of
different thread forms for the pull groove portion and
locking groove portion of the pin;
Figure 13a is a pictorial view with some parts
shown broken away and others shown in section of a modified
swage fastener of a fit-up type including a collar with a
flexible tab for engagement with a threaded pin;
Figure 13b is a pictorial view of the collar of
Figure 13a;
Figure 14 is an elevational view of a swage type
fastener having a modified pin structure where the locking
groove and pull groove portions have opposite hand threads
and with the' pull groove portion being of a reduced
diameter whereby a collar with a limited thread can be
threaded onto the locking groove portion;
Figure 15 is an elevational view similar to
Figure 14 bu.t showing a different form of swage type
fastener with the pin having opposite hand threads for the
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locking groove and pull groove portions but with such
portions being of a similar dimension and with the collar
having a flexible tab such as depicted in Figure 11;
Figure 16 is an elevational view of a swage
type fastener_ depicting the fastener with a threaded pin
after it has been set with the pin being deformed by the
swaged collar. to have an hour glass configuration whereby
removal of the swaged collar by unthreading is resisted;
Figure 17 is a fragmentary elevational view of
a swage type fastener and a portion of an installation tool
with the pin having an internal thread at its outer shank
end and with the tool portion having a threaded mandrel
adapted to engage the internal thread to apply thereby a
relative axial force for setting the fastener;
Figure 18 is a fragmentary elevational view of
a swage type fastener and portion of an installation tool
similar to that of Figure 17 but with the pin having both
internal and external gripping threads and with the tool
portion having a mandrel and a nut for separate engagement
of both the .i.nternal and external threads for setting the
fastener;
Figure 19 is a drawing depicting the
installation apparatus of the present invention and
including a longitudinal sectional view of an installation
tool for use with the controller system shown in Figure 20;
Figure 20 is a block diagram of a controller
system including portions of the installation tool of
Figure 19 and embodying features of the present invention;
and
Figure 21 is a fragmentary view depicting a
variation of the installation tool of Figure 19.
Referring to Figures 1 through 4, there is shown
a multi-piece fastener 10 that includes a pin 12 and
tubular collar 14. The pin 12 includes an enlarged head 16
and a pin shank 18 adapted to be received in aligned
openings 20 and 22 in a pair of workpieces 24 and 26,
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respectively. The fastener 10 is a swage type fastener
with the pin. 12 being of a stump type construction but
which is adapted to provide installation as a pull type
fastener; alternatively the pin 12 facilitates installation
of the fastener 10 as a stump type fastener. Thus the pin
shank 18 is constructed without a pintail portion and
breakneck groove for severing such pintail portion. Pin
shank 18 has a smooth shank portion 28 adjacent the
enlarged head 16 followed by a lock groove portion 30 (in
brackets) having locking grooves 32 and terminating in a
short pull portion 34 (in brackets) having helical pull
grooves 36. In the embodiment shown in Figures 1-4 the
lock grooves 32 and pull grooves 36 are defined by a
uniform, continuous helical thread which can be of a
standard thread form such as a UNC and/or UNF thread form.
Collar 14 is of a cylindrical construction with an
elongated co:Llar shank 40 terminating at one end in an
enlarged flange 38. The collar 14 is adapted to be
received upon the threaded lock groove portion 30 via a
smooth through bore 42 of generally uniform diameter.
Th.e fastener 10 can be used to join together
workpieces 24 and 26 of varying combined thicknesses from
a maximum thickness X to a minimum thickness X'. The
length of the pin shank 18 is selected to be minimal to
accommodate workpieces varying in such total thickness
within this grip range. In order to accomplish this, the
pull portion 34 is maintained at a minimal length. Thus
the pull portion 34 is of a short, limited length Y such
that the excess length of pin shank 18 extending beyond the
outer end of collar 14 will be Y for a maximum grip
condition X and a greater distance of Y' for a minimum grip
condition X'., As will be seen, the length Y of pull
portion 34 is selected to provide a sufficient number of
threads to accept the pulling force to be applied
therethrough to set the fastener 10 as a pull type
fastener. In addition the pin shank 18 can be provided
with a slight excess length such that the pull portion 34
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will be spaced from the outer end of the collar 14 before
and after swage for a purpose to be described.
Figures 1-4 show a portion of a tool 44 for
installing the modified stump type fastener 10 as a pull
type fastenez-. The tool 44 comprises a rotary nut member
46 having internal gripping threads 48 sized to threadably
engage the helical pull grooves 36 of pull portion 34. The
tool 44 further includes an annular anvil member 50 having
a swage cavity 52 which receives the nut member 46; as will
be seen, the anvil member 50 is connected to an outer,
anvil housing 54 adapted for axial movement relative to the
nut member 46. The swage cavity 52 of the anvil member 50
is of a generally circular cross section of a diameter OD
which is smaller than the circular outside diameter OD' of
collar shank 40 such that as the anvil member 50 moves
axially along and radially over collar shank 40, the collar
material is swaged radially into the helical locking
grooves 32 on pin shank 18, thereby securing the pin 12 and
collar 14 to each other and securing the workpieces 24 and
26 under a desired clamp load. The swaging occurs
generally over 360° of the engaged circumference of the
collar shank 40 and generally over the majority of its
length, i.e. preferably between around 75% and around 900
of the length of collar shank 40.
Figure 2 shows the tool 44 after nut member 46
has been threaded to a predetermined position onto the pull
portion 34 of pin shank 18 to initially grip the pin 12.
Next, as shown in Figure 3, the tool 44 is actuated to
cause the anvil housing 54 to move axially forwardly
relative to t:he nut member 46 and hence relative to the
gripped pin 12. This action brings the swage anvil member
50 into engagement with the outer end of the collar shank
to apply a relative axial force between the pin 12 and
collar 14. As this force continues the workpieces are
35 initially clamped together under a desired preload. The
relative axial force increases moving the anvil swage
cavity 52 axially to radially overengage the collar shank
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40 to swage the collar material radially into the locking
grooves 32 of the pin 12. After the swaging step has been
completed the relative axial force between the anvil
housing 54 and the nut member 46 is reversed whereby the
swaged collaz- shank 40 is ejected from the swage anvil 50
(see Figure ~6). T:he nut member 46 is now reverse rotated
to remove it from the pin pull portion 34 and the
installation is complete; with workpieces 24 and 26 of
maximum grip or combined thickness X, the set fastener 10
will have a minimal excess length Y of pin shank 18
extending beyond the outer end of the collar shank 40.
Thus no pintail portion is required resulting in the
advantages previously noted.
In a preferred form of the invention, the pull
portion 34 at maximum grip X is located a minimal clearance
distance of around one thread pitch P from the outer end of
the collar shank 40 after initial clamp up and prior to
swage (see Figures 1 and 2). This clearance P is selected
to avoid engagement of the outer end of collar shank 40
with the nut member 46 upon elongation of the shank 40 from
swage whereby loading of the engaged threads between the
nut member 46 and pull portion 34 is avoided or negligible
such that the removal torque required on the nut member 46
can be kept low permitting the use of a small capacity
rotary motor whereby the overall size of tool 44 can be
minimized.
The internal gripping threads 48 of the nut
member 46 are of greater strength than the threaded pull
grooves 36. Nut member 46 can be formed from a high
strength alloy or case hardened material having a hard,
wear-resistant surface on its internal gripping thread 48.
In one form of the invention nut member 46 was formed of a
ferrous material having a Rockwell hardness of around 50
Rc.
In the form of the fastener 10 of Figures 1-4
the pin 12 can be constructed of a ferrous material and
have a Rockwell hardness of around 33 to around 39 Rc for
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a grade 8 type fastener and a hardness of around 25 to
around 35 Rc for a grade 5 type fastener; however, in order
to enhance the strength of the pull grooves 36 and hence
minimize the necessary overall length of pull portion 34,
the pull portion 34 can be hardened to a Rockwell hardness
of at least .around 5 Rc greater than the hardness of the
remainder of the shank or preferably abound 15 Rc harder.
In any event it is desirable that no more than around four
threads or pull grooves 36 be required to sustain the
relative axial pulling loads required to set the fastener.
In this regard, it is desirable that the number of pull
grooves 36 be: selected having a shear strength no greater
than around 30% and preferably 20% more than that required
to sustain tree maximum load applied to the fastener 10 by
the tool 44 to set the fastener 10 in a maximum grip
condition. Thus the number of threads of the helical pull
grooves 36 engaged is selected to provide adequate strength
to withstand. the relative axial pulling load to be
subsequently applied in setting the fastener 10.
In. the embodiment shown in Figures 1-4 the
internal gripping threads 48 on nut member 46 and threaded
pull grooves 36 can be of a generally conventional, mating
construction. However, it may be advantageous to use a
somewhat modified thread on the nut member. Such a
modified structure is shown in Figure 5 where components
similar to like components in the embodiment of Figures 1
to 4 are given the same numeral designation with the
addition of the letter postscript "a" and unless described
otherwise are substantially identical with the like
components of Figures 1-4. Looking now to Figure 5 the
threads of the nut member are constructed to facilitate
initial engagement. Thus the internal gripping threads 48a
of nut member 46a have shoulders 55 which are of a width W
which is less than the width W' of associated grooves 55'
across the pitch line. In one form of the invention the
shoulder width W across the pitch line was around 75% of
groove width W'. Also the crest diameter D of each
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gripping thread shoulder 55 closely approaches the root
diameter D' of the pull grooves 36a in order to maximize
the effective shear are of the pull grooves 36a. Thus, the
gripping threads 48a, utilizing the features noted, are
configured relative to the helical pull grooves 36a to
facilitate initial engagement onto the pull portion 34a
without cross threading or thread stripping and to enhance
the effective' shear areas. It will be seen, however, that
various combinations of internal gripping threads 48, 48a
on nut member 46, 46a and pull grooves 36, 36a on pull
portion 34, _94a can be advantageously utilized.
In some applications, it may be desirable that
the locking groove portion not be threaded and that the
locking grooves be annular and not helical. Such a
construction is shown in the embodiment of Figure 6 where
components similar to like components in the embodiment of
Figures 1 to 4 are given the same numeral designation with
the addition of the letter postscript "b" and unless
described otherwise are substantially identical with the
like components of Figures 1 to 4.
Thus looking now to Figure 6 , the pin 12b has
its locking groove portion 30b formed with locking grooves
32b which are annular, i.e. generally circular and not
helical, see '048 and '049 patents to L. Huck. The
remainder of the structure of fastener lOb is the same as
fastener 10 such that pull grooves 36b of pull portion 34b
are defined by a helical thread form whereby the
installation of fastener lOb will be essentially the same
as that for fastener 10.
As indicated, the fit-up fastener construction
of the R. Dixon patent could be used advantageously in the
present invention to provide initial pull together of the
workpieces and hence to assist in providing that the
desired length of pin pull portion will be accessible to
the nut member-. Such a construction is shown in Figures 7
to 10 where components similar to like components in the
embodiment of Figures 1-4 have been given the same numeral
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designation with the addition of the letter postscript ~~c~~
and unless described otherwise are substantially identical
with the like components of Figures 1 to 4.
Looking now to Figures 7 to 10, a fastener lOc
is shown to include a pin member 12c and tubular collar
14c. Pin member 12c has an elongated shank 18c which
extends with a clearance fit through aligned openings 20c
and 22c in a pair of workpieces 24c and 26c, respectively,
to be secured together. An enlarged protruding head 16c at
one end of pin shank 18c engages one side of workpiece
26c. A straight shank portion 28c extends from pin head
16c and is followed by a lock groove portion 30c defined by
a plurality of lock grooves 32c having a continuous,
helical thread form. The outer end of the pin shank 18c
terminates in a pull portion 34c having a plurality of pull
grooves 36c defined by a continuous, helical thread form.
The tubular collar 14c has a generally straight
shank 40c terminating in an enlarged flange 38c. Both the
pin head 16c and collar flange 38c can be provided with
wrenching flats to facilitate gripping by a wrench or other
suitable tool for applying a relative torque between the
pin member 12c and collar 14c (see Figures 7 and 9). With
regard to the latter, the collar 14c has a generally smooth
bore 42c of an internal diameter to be in clearance with
the pin shank 18c; a female thread 56 is formed at the
flange end of the bore 42c and is adapted to
complementarily, threadably engage the helical locking
grooves 32c. For a reason to be seen the collar thread 56
is of a limited extent.
In operation, then, the workpieces 24c and 26c
can be first joined together by the threaded engagement
between the limited collar thread 56 and the threaded lock
grooves 32c. The wrenching surfaces on the pin head 16c
and collar f:Lange 38c facilitate torquing to a desired
magnitude or extent of clamp. After this has been
accomplished the installation tool 44c is applied to the
fastener lOc and a relative axial force is applied between
CA 02256996 1999-09-13
- 17 -
the pin 12c and collar 14c via the nut member 46c
threadably engaging the threaded pull grooves 36c of pull
portion 34c and the swage anvil member 50c engaging the
outer end of the collar shank 40c. As the relative axial
force increases, the limited collar thread 56 will shear or
deform sufficiently to permit the shank 40c of collar 14c
to move further axially relative to the pin 12c. Figure 8
depicts the fastener lOc after the nut member 46c has been
threaded onto the pull grooves 36c, the collar thread 56
has been deformed, and the relative axial force has been
increased to initially swage or snub the collar 14c into
the lock grooves 32c. In this condition, the pin 12c and
collar 14c will now act in the same manner as pin 12 and
collar 14 in. the embodiment of Figures 1-4. Thus the
workpieces 24c and 26c are clamped together at a
preselected preload by the relative axial force initially
applied by the tool 44c between the pin 12c and collar 14c;
as the axial force increases, the collar shank 40c is
swaged into the helical locking grooves 32c completing the
swaging operation (see Figure 10). Subsequently, upon
further actuation of the tool 44c the swaged collar shank
40c will be ejected from the anvil swage cavity 52c and the
nut member 46c threaded off from the pull portion 34c thus
completing the installation.
Note that the contour of the swage cavity 52c of
the anvil member 50c and the contour of the outer end of
the collar shank 40c are such that swaging of the collar
shank 40c into the locking grooves 32c will not start to
occur at the. lower magnitude of relative axial force
required to shear or deform the limited collar thread 56 at
the initiation of the swage step.
In one form of the invention, the helical
locking grooves 32c are of a shallow construction and have
a contour closely approximating a streamlined root
configuration as shown in the Dixon patent. With the
fastener construction of Figures 7-10, it has been found
that the depth of the locking grooves 32c can be selected
CA 02256996 1999-09-13
- 18 -
to provide a desired minimum ratio of depth h to the crest
diameter Du of the pin 12c. The major criteria of groove
depth h is i:hat it be sufficiently deep as a practical
matter to receive and retain the material of the collar 14c
after swage. A groove depth h of around 0.04 x Du or less
is desirable,, i.e. (h/Du) x 102 - 4. With such a shallow
groove, the :root diameter Dr will be maximized for a pin
with a given crest diameter Du. This will provide that a
pin 12c of a given material will have nearly the maximum
tensile strength available since tensile failure would
generally occur across the root diameter Dr which, when
maximized, is only slightly less than the crest diameter
Du. The maximized root diameter Dr will also provide
improved fatigue life.
With a shallow groove construction, it is
desirable to provide the collar shank 40c with a volume
such that when swaged into the helical locking grooves 32c
it will have an excess volume over that required to fill
the grooves 32c. In one embodiment, the volume of collar
shank 40c was selected to provide 'overpacking', i.e., a
volume of coT_lar shank 40c to provide substantially more
volume of col:Lar material for filling grooves 32c than they
could normally accept within the swage envelope of the
swage cavity 52c of anvil member 56c and the confronting
portion of pin 12c. It has been found desirable to provide
a volume of collar material which has an excess of at least
around 16%. The percentage 'overfill' or 'overpacking'
noted can be generally determined in the manner described
in the noted :Dixon patent.
Because of the shallowness of the locking
grooves 32c, it is desirable that the pin 12c be hard
enough relatirre to the hardness of the collar 14c to resist
crushing or substantial yielding in tension or necking down
from the high compressive swage loads. Thus, in one form
of the invention, the pin 12c could be made of AISI 4140
alloy steel or AISI 1541 carbon steel having an ultimate
shear strength of at least around 95 KSI. The collar 14c
CA 02256996 1999-09-13
- 19 -
could be made of AISI 1035 carbon steel having an ultimate
shear strength of at least around 45 KSI. Generally it is
desirable to utilize a pin 12c having an ultimate shear
strength relative to that of collar 14c in the ratio in a
range of around 1.8:1 to around 2.4:1. Thus the pin 12c
has a sufficient hardness to accept both the high tensile
preloads desired and the swage loads on the collar 14c
substantially without yielding. The wall thickness of
collar shank 40c is selected to provide the necessary
material to promote swaging into the shallow helical
locking grooves 32c and flow in elongation to provide the
desired clamp load. At the same time, the collar wall
thickness at final swage is also selected to provide
sufficient, radial stiffness or hoop strength to resist
significant radial spring back from the locking grooves 32c
both during initial swage and also under subsequent tensile
loading. Also, the volume of the collar 14c and swage
cavity 52c are selected to provide movement of the material
of collar shank 40c into the locking grooves 32c to assure
a good fill. See the noted Dixon patent.
It is also desirable, that the widths of the
groove portions 57 and pin shoulder portions 58 of locking
grooves 32c and the complementary groove portions 59 and
shoulder portions 60 of the swaged collar 14c be
proportioned in width relative to the respective shear
strengths of the materials of pin 12c and collar 14c such
that both the pin shoulder portions 58 and the collar
shoulder portions 60, defined by interlocking material of
the swaged collar 14c, are in incipient or simultaneous
failure in shear at or above the preselected minimum
ultimate design tensile load for the fastened joint of
workpieces 24c and 26c (see Figures 7 and 10). It is
preferred that. the design provide for the collar shoulder
portions 60 to fail prior to the pin shoulder portions 58,
i . a . the pin shoulder portions 58 would fail in shear at
approximately 110% of the tensile load at which the collar
shoulder portions 60 would fail. By proportioning the
CA 02256996 1999-09-13
- 20 -
grooves as nated, the engaged length of pin and collar can
be minimized for a given tensile load. Of course, by
providing sufficient collar length, the above shear
strength relationship can be maintained while providing for
a tensile failure diametrically across the pin lock groove
portion 30c.
Another advantage of employing proportioned
strength as noted is that the shear strength of the limited
collar thread 56 can now be maximized permitting the pre-
fastened clamp via torquing to be at a relatively high
magnitude and/or permitting the fastener lOc in its pre-
fastened clamp condition to withstand the necessary loads
to hold the ;structure together during a fit-up operation.
This is achieved by virtue of the fact that the width of
collar threat. 56 is substantially the same as the width of
the pin groove portions 57 of helical locking grooves 32c.
While the preceding relationships are taught in
the noted Dixon patent they can be of particular advantage
in combination with the present invention. Thus, for
example, in some instances the workpieces could be pulled
together removing the gap therebetween and assuring that a
minimum length pin could be used.
In some applications it is desirable that the
fastener be readily removed the same as a nut and a bolt.
However, in a. swage type fastener with a threaded pin the
forces applied to the pin by the collar material during
swage could result in distortion of the pin thread such
that removal of the collar by unthreading would be severely
hampered. With the fastener lOc, the pin 12c is
constructed of a high strength material relative to the
strength of the collar 14c and the lock grooves 32c are of
the shallow form all as previously described; this results
in little distortion of the lock grooves 32c from the
swaged collar 14c thereby facilitating removal of the set
fastener lOc by simply unthreading the swaged collar 14c
from the pin 12c.
As previously noted, it is desirable that the
CA 02256996 1999-09-13
- 21 -
nut member 46c be readily, threadably applied to the
helical pull grooves 36c. In the embodiment of Figure 5
the internal gripping threads 48a of nut member 46a were
configured to facilitate initial engagement with the pull
portion 34a where the pull grooves 36a had a generally
standard thread form. But such initial engagement is also
facilitated by a construction of pull grooves where the
crests or shoulders are of a lesser width than the width of
the associated grooves. In the embodiment shown in Figures
7 to 10, the helical pull grooves 36c are a continuation of
and of the same construction as the associated locking
grooves 32c previously described. For purposes of ease of
engagement it is believed that a ratio of the width of pin
groove portions 57 of pull grooves 36c to the width of pin
shoulder portions 58 of around 1.25:1 and greater may be
desirable. On the other hand and as noted, a ratio of
around 1.8:1 to around 2.4:1 would be more desirable for
the full advantage of proportioned strength of the locking
grooves 32c in the locking groove portion 30c. The lower
ratio for the pull groove portion 34c is also desirable to
provide increased shear area and hence shear strength to
resist the pull loads. Both can be accommodated by
providing the locking grooves 32c to be constructed to have
the higher r<~tio for proportioned strength and the pull
grooves 36c to have a lower ratio for increased shear
strength to resist the pull load. This would also permit
the use of fewer pull grooves thereby facilitating the
construction of a pull portion of a minimum length. Such
a construction is shown in Figure 11 where components
similar to like components in Figures 7 to 10 have been
given the same numeral designation with the addition of the
letter postscript "d".
Looking now to Figure 11, the pin 12d has a lock
groove portic>n 30d with locking grooves 32d and a pull
portion 34d with pull grooves 36d. The width Wg of the
groove portions 57d of locking grooves 32d is greater than
width Wg' of groove portions 57d' of pull grooves 36d. At
CA 02256996 1999-09-13
- 22 -
the same time the width Ws of lock groove shoulder portions
58d is less than the width Ws' of pull groove shoulder
portions 58d'. In this way the lock groove portion 30d can
be constructed to optimize the advantages of proportioned
strength while the pull portion 34d can be optimized to
provide ease of initial engagement by the nut member and
adequate shear strength over a minimal length to resist the
applied pull loads. Note that the thread pitch Pd can be
maintained the same for both the threads on the lock groove
portion 30d and on the pull portion 34d. In this case the
collar thread, such as thread 56 in Figure 7, can be
constructed to accept the threads of both the lock groove
portion 30d and the pull portion 36d. Note that in the
construction shown in Figure 11 the root diameter Drd is
the same for both the threads of the lock groove portion
30d and the pull portion 36d. By the use of a nut member
constructed generally as shown in Figure 5, the ease of
initial engagement will be further enhanced.
Another means of providing for a similar,
balanced difference in threaded groove constructions would
be to make the root of the pull grooves deeper thereby
providing wider pull groove shoulders at the root. Such a
construction .is shown in Figure 12 where components similar
to like components in the embodiment of Figure 11 are given
the same numeral designation with the addition of the
letter postscript "e".
Looking now to Figure 12, the pin 12e has a lock
groove portion 30e with locking grooves 32e and a pull
portion 34e with pull grooves 36e. The groove portions
57e' of pull. grooves 36e are deeper than the groove
portions 57e of locking grooves 32e and hence have a root
diameter Dre' smaller than locking groove root diameter
Dre. Thus the width Wse of lock groove shoulder portions
58e is less than the width Wse' of pull groove shoulder
portions 58e'. In this way the lock groove portion 30e can
again be constructed to optimize the proportioned strength
advantages while the pull portion 34e can be optimized to
CA 02256996 1999-09-13
- 23 -
provide adequate shear strength over a minimal length to
resist the applied pull loads. With a nut member
constructed <~enerally as shown in Figure 5, the ease of
initial engagement will also be present. As with the prior
embodiment, the thread pitch Pe can be maintained the same
for both thread farms so as to accept the collar thread
such as thread 56 of Figures 7-10.
As. noted another fit-up fastener construction
could be used. employing the flexible tab-like structure of
the Smith patient (supra); such a construction is shown in
Figure 13 where components similar to like components in
the embodiment of Figures 7 to 10 are given the same
numerical designation with the addition of the letter
postscript "f" and unless described otherwise are
substantially identical with the like components of Figures
7 to 10.
Thus looking now to Figure 13 fastener lOf is
shown to include a pin member 12f and tubular collar 14f.
Pin member 12f has an elongated shank 18f which extends
through aligned openings 20f and 22f in a pair of
workpieces 24f and 26f, respectively, to be secured
together. Ari enlarged protruding head 16f at one end of
shank 18f engages one side of workpiece 26f. Adjacent the
head 16f, the shank 18f has a straight portion 28f which is
adapted to be received within aligned bores 20f and 22f
with a clearance fit. Following the straight portion 28f
is a lock groove portion 30f defined by locking grooves 32f
in the form of a continuous helical thread. The pin shank
18f terminates in a pull portion 34f defined by pull
grooves 36f which are also in a helical thread form and can
be a continuation of the thread form of lock grooves 32f.
The tubular collar 14f has a generally straight
collar shank 40f terminating in an enlarged flange 38f.
The collar 14:E is provided with a flexible tab 56f located
generally at t:he forward end of the collar shank 40f within
smoot h bore 4 2 f .
In operation the pin 12f is located in the
CA 02256996 1999-09-13
- 24 -
workpiece bores 20f and 22f and the collar 14f is located
over the pin shank 18f. The flexible tab 56f extends
radially inwardly sufficiently to engage the ridges of the
lock grooves 32f. The tab 56f, however, being flexible can
deform or bend over the ridges of the lock grooves 32f
until the collar flange 38f engages the workpiece 24f. The
tapered or wedge like construction of the flexible tab 56f
facilitates movement of the collar 14f onto the pin 12f.
In some applications, it is advantageous to have
the workpieces 24f and 26f lightly clamped or even loosely
held together to permit an appropriate fit-up of the
associated structure prior to final installation. After
the pin 12f and collar 14f have been preassembled as noted
the installation tool (such as tool 44c), is applied in the
manner previously described, to the fastener lOf, by
threading the nut member (such as 46c) onto the pull
grooves 36f; :next a relative axial force is applied between
the pin 12f and collar 14f via the nut member (such as nut
member 46c) dripping the pull groove portion 34f and the
swage anvil (such as 50f) engaging the outer end of the
shank 40f of collar 14f. As the relative axial force
increases the flexible tab 56f will deform sufficiently to
permit the collar 14f to move further axially relative to
the pin 12f. The workpieces 24f and 26f can now be clamped
together at a preselected preload by the relative axial
force initially applied between the pin 12f and collar 14f
and, as the axial force increases, the collar 14f is swaged
into the lock groove portion 30f. Subsequently, upon
further actuation of the tool the swaged collar 14f will be
ejected from the anvil (such as 50f) and the nut member
spun off thus completing the installation.
Note that the contour of the swage cavity of the
anvil (such as 50c) and the contour of the outer end of the
shank 40f of collar 14f are such that swaging of the collar
14f into the lock grooves 32f will not start to occur at
the lower magnitude of relatively axial force required to
deform, and in a sense to ratchet, the flexible tab 56f
CA 02256996 1999-09-13
- 25 -
over the lock grooves 32f during the pull up of the
workpieces 24f and 26f at the initiation of the swage
operation.
Although a variety of materials would be
suitable for the tab 56f, a flexible urethane of about a
Shore A70 to around a Shore A90 hardness was found
satisfactory. Another suitable material for tab 56f is an
ethylene copolymer such as ethylene vinyl acetate of about
a Shore A70 to around a Shore A90 hardness.
In some applications it may be desirable to
provide the threads of the pull portion to be of a reverse
hand to that of the lock groove portion. In this way, any
tendency to turn the swaged collar threads off from the
threaded locking grooves on removal of the nut member of
the tool would be obviated. Such a construction is shown
in Figure 14 where components similar to like components in
the embodiment of Figures 7 to 10 are given the same
numeral designation with the addition of the letter
postscript "g" and unless described otherwise are
substantially identical with the like components of Figures
7 to 10.
Thus looking now to Figure 14 , the pin 12g of
fastener lOg has a lock groove portion 30g with the helical
locking grooves 32g being in the form of a right hand
thread. The ;pull portion 34g is provided with ids helical
pull grooves 36g in the form of an opposite or left hand
thread. Thus after the completion of the swage step, when
the nut member of the tool (not shown) is oppositely
rotated to disengage from the helical pull grooves 36g on
pull portion :34g the reaction on the pin 12g to the removal
torque will tend to torque the pin 12g relative to the
collar 14g to tighten the connection rather than loosen it.
In the embodiment shown in Figure 14, the pull portion 34g
is of a reduced diameter relative to the lock groove
portion 30g such that the limited collar thread 56g can be
axially moved in clearance over the pull portion 34g and
threaded onto the lock groove portion 30g. Where a non-
CA 02256996 1999-09-13
- 26 -
threaded collar is used the pull portion 34g can be of the
same diameter as the lock groove portion. This is shown in
Figure 15 where components similar to like components in
the embodiment of Figure 14 are given the same numeral
designation with the addition of the letter postscript "h"
and unless described otherwise are substantially identical
with the like: components of Figures 7 to 10 and 14.
Thus in Figure 15 the pull portion 34h of pin
12h is of the same diameter as the lock groove portion 30h
with the helical locking grooves 32h being of an opposite
hand thread to the helical pull grooves 36h. The length of
the pull pori:ion 34h, however, is increased such that it
will have at least one thread 61 in line with the collar
shank 40h; in this way when the collar shank 40h is swaged
onto the pin shank 18h some of the collar material will be
swaged onto t:he opposite hand thread of the pull grooves
36h which will provide an anti-rotation feature resisting
loosening from vibration. Note also that the combination
of opposite hand threads will provide a substantially
tamper proof joint. Note that a collar, such as collar 14f
having a flexible tab 56f, could be used to provide the
fit-up function regardless of the use of the combination of
right and left hand threads of same diameter on pin shank
18h.
Another tamper proof construction is shown in
Figure 16 where components similar to like components in
the embodiment of Figures 1 to 4 have been given the same
numeral designation with the addition of the letter
postscript "i" and unless described otherwise are
substantially identical with the like components of Figures
1 to 4.
Looking now to Figure 16 the lock groove portion
30i of pin 12i of fastener l0i can be formed with standard
UNC or UNF threads and can be made of a material which is
somewhat soft relative to the material of the collar 14i.
Thus upon swaging the collar shank 40i into the lock groove
portion 30i, the lock groove portion 30i will neck locally
CA 02256996 1999-09-13
- 27 -
such that the diameter Dch in the center is less than the
diameter Deh at opposite ends; this defines an "hourglass"
or concave configuration which resists unthreading of the
swaged colla~~ 14i from the pin 12i. Such a construction
can be provided where the pin 12i had a standard thread
form and was of a ferrous material having a hardness of
around 35 Rc and the collar 14i was of a ferrous material
having a hardness of around 75 Rb. This relationship would
differ for different thread forms such as the shallow lock
grooves herein described. Localized necking has occurred
in swage type fasteners with annular grooves but is
generally avoided with threaded grooves where removability
by unthreading is desired. The hour glass construction
resists rotation and unthreading of the swaged collar 14i
from the pin 12i such that the set fastener provides a
tamper proof construction. The degree of concavity need
not be extreme but in some cases will provide sufficient
resistance to removal by torquing where the center diameter
Dch has been reduced by at least around 2% relative to the
end diameter Deh. Note that the threaded pull portion 34i
could be hardened, as previously noted, to increase the
strength of the helical pull grooves 36i.
It is desirable that the pull portion be
maintained as short as possible; yet the minimum length of
the pull portion is dictated by the minimum number of pull
grooves required to provide sufficient shear strength to
withstand the pulling loads to set the fastener. In some
constructions the pull portion can be defined by internal
threads at the end of the pin shank adapted to be gripped
by a threaded male mandrel. Such a construction is shown
in Figure 17 where components similar to like components in
the embodiment of Figures 1 to 4 have been given the same
numeral designation with the addition of the letter
postscript "j". Thus looking now to Figure 17, the pin 12j
of fastener lOj has a lock groove portion 30j extending
generally over the outer end of the pin shank 18j. The
outer end of pin shank 18j is formed with an axial bore 64
CA 02256996 1999-09-13
- 28 -
defining the pull portion 34j; the bore 64 is provided with
internal, female helical pull grooves 36j. The tool 44j
has an axially extending threaded male, mandrel 66 adapted
to threadably engage the internal pull grooves 36j whereby
the relative axial force can be applied between internal
pull grooves 36j and the swage anvil member 50j to set the
fastener lOj in the manner as described before. Thus with
this construction the overall length of the pin shank 18j
can be minimized.
In. another form of the invention the pull
portion of the pin can be defined by a combination of
external and internal threads. Such a construction is
shown in Figure 18, where components similar to like
components in the embodiments of Figures 1-4 and 17 are
given the same numeral designation with the addition of the
letter postscript "k". Thus looking now to Figure 18, the
fastener lOk has pin 12k a lock groove portion 30k
terminating in a limited pull portion 34k having external
helical pull grooves 36k and internal helical pull grooves
36k' in an a;tcial bore 64k. The tool 44k in addition to
having nut member 46k which will engage the external,
helical pull grooves 36k is provided with an axially
extending threaded male, mandrel 66k adapted to engage the
internal pull grooves 36k'. The mandrel 66k is separate
from the nut member 46k so that each are threaded
separately onto the mating internal pull grooves 36k' and
external pull grooves 36k, respectively. The combination
of internal and external pull grooves will also permit the
use of a pul7_ portion 34k of minimal length resulting in
pin shank 18k being minimal in length.
The tool 44 also represents a unique element of
the fastening system of the present invention and is shown
in greater detail in Figure 19. Figure 19 illustrates
structural features of the tool 44 operating in accordance
with the sequE~nce shown in Figures 1 through 4 and is shown
in combination with a control system 67 shown in Figure 20
to be described.
CA 02256996 1999-09-13
- 29 -
Thus looking to Figures 19 and 20 and Figures 1-
4, the tool X64 has a sensing rod 68 which extends axially
through nut member 46 to detect the extent that the nut
member 46 has been moved onto the pull portion 34 of pin
shank 18. As the nut member 46 is rotated by a reversible
air motor 70 it advances axially on the pull portion 34
until sensing' rod 68 contacts the end surface of pin shank
18 and is moz~ed axially rearwardly relative to nut member
46. The rearward movement of sensing rod 68 and/or a timer
is used to determine actuation of a source of compressed
air 71 for the motor 70 that rotates nut member 46. The
movement of sensing rod 68 may also be used to determine
actuation of a fluid power source 69 to move anvil member
50 axially relative to nut member 46 such that it will
first engage the outer end of the collar shank 40 to apply
an initial preload to the workpieces 24 and 26 and then
upon continuesd actuation will move axially to radially
overengage the collar 14 swaging it into locking grooves 32
on the pin shank 18.
The tool 44 includes an elongated annular
housing assembly 72 having a central, longitudinal axis 74.
The housing assembly 72 has a cylinder housing 76
internally contoured to form a fluid cylinder cavity 78.
A piston 80 is disposed within cylinder housing 76 for
reciprocating movement in the cylinder cavity 78 in
response to selective introduction of hydraulic fluid
through ports 84 and/or 86 in the cylinder housing 76.
Cylinder housing 76 is threadably connected to outer anvil
housing 54 via a threaded connection 88 and hence is
connected to swage anvil member 50 whereby the piston 80
will move axially relative to the anvil member 50 as shown
in Figures 1 through 4 to swage collar 14 onto pin 12.
Swage anvil member 50 is also threadably connected to the
forward end of outer anvil housing 54 via a threaded
connection 90. Housing assembly 72 also includes rear
housing member 92 which is affixed to the cylinder housing
76 via a ring of bolts 94.
CA 02256996 1999-09-13
- 30 -
The nut member 46 is rotatably mounted within
the swage cavity 52 of anvil member 50. Nut member 46 is
rotatably driven around the tool axis 74 by the reversible
air motor 70. The drive system includes a first bevel gear
96, a second bevel gear 98, and an elongated drive shaft
100. Shaft 7.00 extends axially through piston 80 but can
rotate relative thereto to impart the rotary drive force to
nut member 46.
Fluid piston 80 includes a piston head 102 and
a piston rod 104 with the piston head 102 dividing the
fluid cylinder cavity 78 into forward and rearward chambers
106 and 108, :respectively. A tubular extension 110 extends
rearwardly from piston head 102 through a bore 112 in the
end wall 114 of cylinder housing 76. Introduction of
pressurized hydraulic fluid through port 84 into the
forward cylinder chamber 106 causes a hydraulic force to be
exerted on the forward or rod end of piston 80 to drive the
piston 80 axially rearwardly relative to housing assembly
72. Introduction of pressurized fluid through port 86 into
the rearward cylinder chamber 108 causes a hydraulic force
to be applied to the rearward or head end of piston 80
causing it to move axially forwardly, i.e. to the position
shown in Figures 1 and 19.
Air motor 70 is attached to rear housing member
92 in a radial orientation such that the motor rotational
axis 116 extends radially or transversely from central
housing axis '74. A motor shaft 118 carries the first bevel
gear 96 that meshes with the second bevel gear 98 supported
in anti-friction bearings 120 for rotation around central
housing axis 74 while anti-friction bearings 121 support
the first bevel gear 96 for rotation around its axis 116.
Drive shaft 1.00 is splined with grooves 122 to mate with
ball splines :124 on second bevel gear 98, such that gear 98
can transmit a rotary drive force to drive shaft 100 and
the drive shaft 100 can move axially relatively thereto
along central housing axis 74.
Drive shaft 100 extends forwardly from second
CA 02256996 1999-09-13
- 31 -
gear 98 through piston 80. The extreme forward end of
drive shaft 7_00 is configured as a square cross-sectioned
male drive element 126 seatable within a similarly
sectioned socket 128 formed in the confronting end face of
nut member 4Ei . The outer side surfaces of nut member 46
are cylindri~~al surfaces slidably and rotatably mounted
within the swage cavity 50 of swage anvil 36. An annular
sleeve 130 carried by the piston rod 104 blocks nut member
46 from axial motion while permitting the nut member 46 to
rotate relatively thereto around central housing axis 74.
Th.e elongated, non-rotary position sensing rod
68 extends through nut member 46 and elongated drive shaft
100. The rearward end of sensing rod 68 is attached to a
disk 132 that. is located within an annular ring structure
134 of a stepped construction and which is axially slidable
within rear housing member 92. A coil spring 136 within
nut member 46 biases sensing rod 68 rearwardly to the
position shown in Figures 1 and 19.
During rotary motion of nut member 46 onto pin
pull portion 34 (Figure 2) and in response to its axial
movement onto the pin shank 18, sensing rod 68 engages the
end face of the pin shank 18. The rod 68 is thus moved
rearwardly (as in Figure 2) so that disk 132 moves
rearwardly a slight distance. This slight movement permits
a light spring 138 to slide ring structure 134 rearwardly
in a manner to sequentially operate two electric position
sensing switches 140 and 142. The second switch 142 is
located a very slight distance to the rear of the first
switch 140 such that first switch 140 is actuated before
second switch 142. For example, the first position switch
140 would be actuated when nut member 46 was only partially
threaded onto the threads of pull portion 34, i.e. only two
threads instead of the desired four threads; on the other
hand the second position switch 142 would be actuated only
after the nut member 46 had been fully threaded the desired
amount onto the threads of the pull portion 34, i.e. four
threads.
CA 02256996 1999-09-13
- 32 -
Thus the actuation point for second switch 142
is predetermined and can be selected so that nut member 46
will be threaded a known distance onto the threads of pull
portion 34 such that a sufficient number of threads on the
pull portion 34 are engaged to fully accept the reaction
loads for the swaging of the collar 14 into the lock groove
portion 30.
Position switches 140, 142 are incorporated into
the controller system 67 which includes a programmable
controller 144; the programmable controller 144 includes a
manually actuable trigger switch 146 actuable by the
operator fox initiating the installation cycle by
energizing motor 70 via air supply 71 and starting a timer
148. Assuming that the second position switch 142 is
actuated within the time period allowed by the timer 148,
i.e. approximately one or two seconds, the programmable
controller 144 will signal the air supply 71 to de-energize
motor 70 and i~hen energize a solenoid valve 150 controlling
flow of hydraulic fluid from the fluid pressure supply 69
to port 84 (b'igure 19). With motor 70 and nut member 46
motionless, the hydraulic fluid will act on the rod end of
piston 80 to effectively move the tool housing assembly 72
forwardly, thereby moving anvil 36 forwardly relative to
nut member 46 to perform the swaging operation on collar
14. In this mode the high pressure output line from fluid
source 69 will be connected to the solenoid valve 150 via
control valve 151.
As the anvil 36 reaches the end of the swage
stroke it generates high back pressure on the fluid in the
line leading to port 84. The high back pressure operates
a second fluid pressure switch 154 to signal the
programmable controller 144 to actuate the solenoid valve
150 to its original condition relative to ports 84 and 86.
Port 84 is thus connected to a drain or return line, while
port 86 is-connected to the high pressure side of the fluid
pressure source 69 until return and then held there under
a low idle pressure. Accordingly, housing assembly 72 is
CA 02256996 1999-09-13
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returned rearwardly to its Figure 2 position ejecting the
swaged collar 14 from the swage cavity 52 of anvil 50. A
second fluid pressure switch 154 in the line leading to
port 86 responds to back pressure to signal the
programmable controller 144 to energize motor 70 via the
air source 71 in the reverse direction, whereby nut member
46 is spun off of the threads on pull portion 34 to
approximate the condition shown in Figure 1.
First pasition switch 140 is in the nature of a
safety switch. to enable the programmable controller 144 to
provide a second chance at achieving a collar swage action
if nut member 46 is initially threaded an insufficient
distance onto pin pull portion 34. In this case, if the
timer 148 times out and first position switch 140 is
actuated but second position switch 142 is not actuated
this signifies a minimal but insufficient threading of nut
member 46 onto pull portion 34. The time period for the
first actuation of first switch 140 is around 5 to 10
seconds. If ;switch 140 is not actuated in that time period
the controller 144 will abort the cycle and bring the
system 67 back to its original state requiring another
actuation of the trigger switch 144. Thus in response to
these signals from switches 140 and 142 and timer 148 the
programmable ~~ontroller 144 actuates the solenoid valve 150
to provide hydraulic fluid at a predetermined low, holding
pressure to ~>ort 84. This holding pressure will be less
than the full pressure for swage but of a sufficient, low
magnitude only to move swage anvil 50 against the end of
collar shank 40 to take up the gap between workpieces 24
and 26. In this regard the first fluid pressure switch 152
senses the magnitude of pressure to port 84 and will
generate a signal when the low holding pressure is
attained; in response the controller 144 will interrupt the
cycle and return the piston 80 to its return position.
Thus when the gap is taken up, the programmable controller
144 will have returned the piston 80 to its original
position and will again initiate the timer 148 to give
CA 02256996 1999-09-13
- 34 -
motor 70 a second chance to thread nut member 46 the
required distance onto pull portion 34. If second position
switch 142 is now actuated on the second attempt, then the
swaging operation will be carried out in the desired
fashion as previously described. If the second switch 142
is not actuated on the second attempt, the programmable
controller 144 will return the controller system 67 to its
return condition, reversing the pressure at ports 84 and 86
and actuating' the air supply 71 to unthread the nut member
46 from the pull portion 34.
Thus the controller system 67 is designed so
that the swaging operation will not be attempted until
after second position switch 142 has been actuated, i.e.,
until the system is assured that nut member 46 has been
threaded a sufficient distance onto pull portion 34 to
adequately resist the axial loads imposed by the swaging
operation.
In. a similar manner controller system 67 will
not initiate the actuation of the pull up of the workpieces
via the low holding pressure if first position switch 140
is not actuated within a time prescribed by timer 148, i.e.
lass than around two threads engaged. Again the nut member
46 will be unthreaded from pull portion 34 without the
application of fluid pressure and without application of a
relative axial pulling force to the fastener 10.
In the system of~Figures 19 and 20 a reversible
air motor 70 of a type Model No. MMR-0002X by Micro Motors,
Inc. of Santa Ana, California, U.S.A. was utilized; at the
same time a programmable controller 144 of a type produced
by DeVilbiss U.S.A. was used and can be programmed to
provide the noted sequence of operation by one skilled in
the art.
Figure 21 illustrates the operation of another
tool embodying the invention. In the embodiment of Figure
21 components similar to like components in the embodiment
of Figures 1 through 4 and 19 are given the same numeral
designation with the addition of the letter postscript "m"
CA 02256996 1999-09-13
- 35 -
and unless described otherwise are substantially identical
with the like components of Figures 1 to 4 and 19. In this
case there is no position sensing rod 68. Instead, nut
member 46m of tool 44m is rotated until the end face 156 of
the nut member cavity 158 abuts against the end surface of
pin shank 18m. When this occurs a back pressure is
developed at ~~ reversible air motor (such as motor 70) used
to rotate nut member 46m. Such a back pressure can be
sensed by the controller system (such as system 67) and
upon attainment of a known magnitude can generate a signal
to stop the air motor. After nut member 46m stops
rotating, the swage anvil member 50m is driven axially and
radially over' the collar 14m to swage the collar material
into the threads of lock groove portion 30m on pin shank
18m. Thus t:he operation of the tool 44m is generally
similar to that of the tool 44 in Figure 19, one difference
being that the magnitude of air pressure on the motor (such
as 70) is sensed instead of nut position on the pin via a
sensing rod 68 and such pressure signal is used to halt
rotation of nut member 46m. In this case, however, the
repeatability factor noted with the embodiment of Figure 19
will not be present.
It should be noted that other groove forms could
be used for the locking grooves and pull grooves. For
example the pull grooves could be in the form of a multiple
thread; with a mating thread on the nut member the full
engagement could occur with fewer turns of the nut member.
Also the pull portion of the pin could be colour
coded so as to provide a visual indication to the operator
that the tool nut member has engaged a sufficient number of
pull grooves and/or that the pull groove portion extends
the desired distance beyond the end of the collar shank.
