Note: Descriptions are shown in the official language in which they were submitted.
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UnNULAR AIR-H~MMER APPARA~US ~OR DRILLING HOLES
Industrial ~pplication
The invention relate~ to air-h~mmer appara-
tus employed for drilling hole~ in mining, con-
struction and pro~pecting which use a conce~tric3tring and transport the rock broken up at the bot-
tom of the hole through the central pipe in the
form of ¢ores and chips to the surface b~ means
of the retur~ flow oi the agent p~o~iding motive
power. More specifically~ the in~ention i3 concern-
ed with snnular air-hammer apparatus for drilling
holes~
The invention may be of utility in drilling
holes for ~arious applications such as searching
for mineral deposlt~ in permafrost regions and on
the Continental Shelf~ blasting rock in open pits
and sinking pile foundation~ at construction sites.
~a¢kground of the Inve~tion
Specifi¢ conditions of ~ir-hammer drilling
; 20 render the dust-collecting equipment commonly pro-
vided at the wellhead ineffective as a meQns of
maintaining the du~t content of the atmosphere at
the work~ng place within the limits speciried by
hygisnic~. ~or dodu~bing~ an aerated solution can
bo fed into the hole. However9 as fsr as the
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drilling in permafro~t i8 concerned, this ~ethod
i~ inapplicable: the wall of hole may t}~w and
cs~e or, in the case of pro~pecting, a mineral
30ught may displace from a higher l~vel of a hole
to a lower one ~o that the factual geological data
msy become mi~leading~ ~herefore, air-hammer dril-
ling find~ limited application in permafro~t re-
gion~-
A radical 301ution to the problem o~ thawing
and caving of holes, dedu~ting the drillman~s work-
ing place and ac~uiring trust-worthy geolo~ical
information can be obtained by employing annular
air-hammer drilling apparatus ~hich dispose of the
chips via the central pipe of concentrio string
with a constant cro~s-secltional area connected to
a duet-colleoting equipment~ e.g. a cyclone, at
the ~urface. Since the agent providing motive power
i8 i~olated fro~ direct contact with the wall of
hole and the velocity of the chips-laden return
flow of the agent through the central pipe i8 con-
3tant, the difficulties referred to above are in-
existent in thi~ ca~e.
~ here i~ ~nown an annular air-hammer drilling
apparatue (of. Patent~chrift Nr. 2854461 Bundes-
republlc Deut¢hland, IPC E21C 3/24~ 1978) termedperforator which incorporate~ a rock-cutting tool
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and a~ a~nular hammer reciprocating in a ¢ylind-
rical case with air-dl~tributing port~ and ~trik-
ing again~t the tool. ~he perforator i3 provided
with a non-return val~e and an internal chips re-
ceiver, ~nd i9 employed with a concentric 8tring-
The known p~rforator and ~imilar apparatusfor core drilling rsly on a combined effect of an
impact against~ and a rotary motion of, the tool.
~hey are pro~ided in the form oi air-operated down-
the-hole units in which air reaches the hammer via
the annular gap in the concentric 3tring and the
non-return ~alve. Spent air leaves into the bottom-
hole region.
~he known annulsr air-hammer drilling appara-
tus has an intrioate ~ystem of distributing air,
and many parts thereof are made of light-gauge
~hapes. Therefore, it lack~ operational reliabill-
ty a~d tails to iind a wide-~pread industrial ap-
plicatio~ ~o far.
Also known i~ an annular air-hammer drilling
apparatus (cf. U~R InYento~'s Certi~icate No.n33398,
IPC E21C 3/24, 1985) a hollo~ ¢~lindrical ¢ase
whereof is fitted ~t the front end with a ro¢k-cut-
tin~ tool ha~lng blo~ off ports and contains a
chips recei~er ~nd a stepped annular hammer capable
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of reciprocating back and ~orth. ~he hammer i8
~itted concentrically with the case and i~teract~
with the outside surfsce of 8 ~tepped sleev~
which ha~ in~et and outlet ports and i~ fixed in
the oa~e bore. I~ reciprocatingj the hammer forms
an idle-stroke chamber with the case and a working-
stroke chsmber with the ~tepped sleeYe. Another
sleeve interposed bet~een 8 ~tep of the stepped
slee~e oi ~ larger diameter and the hammer with
provision ior axial displacement hs~ an annular
recess st its midlength fitting whereinto i~ a
pro~ecti~g stop of the h~mmer.
~he abo~e features of desien permit control
Or the time interval during which air is being ad- -
mitted into the working-stroke chamber and, conse-
quently, inc~ease the impact *oroe Or the appara-
tus. But in the kno~n apparatus the outflow oi ~pent
air from the worklng-~troke chamber is pa~sed into
the chips re¢eiver through the ports oi the stepped
31ee~e which are located at some distance from the
bottom hole. Only a ~mall iraction oi the air
~about 20%) escapes into the bottom hole space ~ia
the blow oif porte oi the rock-cuttln~ tool, by-
pa~oing the hammer. Thereiore~ the rate of advance
of the material iorced up the chips receiver in the
i260~54
~orm o~ disintegrated core and chips, as broken
oif at the bottom hole, i~ ~low until the outlet
por~s are reached where a combined current of air
accelerate~ th~ material to the ~peci~ied velocity
of lifting up th~ chip~ recei~er. Such a pattern
of air flow may bring about plugging up of the rock-
cutting tool and the chips receiver at it~ lo~er
~nd by the material. Not excluded i8 al~o an ingress
of particulate material into the working-stroke
chamber through the ports of the air-distributing
~leeve whlch ma~ lead to an abrasiYe wear of the
rubbing ~urfaoes or even to the sizing of the ham-
mer in the ca~e.
A plugging up oi the core receiver~ may cause
the baokpre~sure in the ~utlet line oi the known
annular air-hammer apparatus to ri~e greatly, de-
~tabilizing the operation oi the hammer throughout
a cycle. It~ frequenoy and ~mpaot foroe may devi-
ate from the design values.
All ~n all, these faotors hs~e an ad~erse e~-
fect on the reliability and efficiency of the known
an~ular air-hammer apparatus.
; Summary of the Invention
It is an ob~oct of the invention to improve
i 25 the periormanoe (i.e. inorease the frequenoy and
impaot force of stro~es) of the apparatus.
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.~nother object of the invention iB to increase
the operational reliability of the apparatu~.
These and other ob~ects are realized by pro~id-
ing an annular sir-hammer apparatus for drilling
holes compri~ing a hollow cylindrical case with
a stepped bore; inlet port3 in a ~tep o~ the bore
of a ~maller diameter and outlet ports in a step
o~ the bore of a larger diameter; a rock-cutting
tool attached to the forward end of the case and
provided with a~ axial openlng; a chip~-receiving
sleeve and a stepped ring-~haped hammer which are
both located in the bore o~ the case; whereby the
hammer i8 fitted ¢onoentrically with the ca~e with
pro~ision ~or reciprocating ba¢k and iorth 90 as
to form a working-~troke chamber with the ca~e
and an idle-stroke chamber with the csae, the rock-
cutting tool and the chips-receiving slee~e; the
two chambers alternstely oommunicating ~ia the in-
let port~ with a line ~or ~eeding a compres~ed ga~e-
ou8 fluid and Yia the outlet ports with the bottomhole~ wherein according to the invention the ¢hips-
recei~ing slee~e has a cylindrical protuberance .
Bt its upper end which interaots with the hammer,
when thi~ come~ into its topmo~t position, and
separates the idle-stroke chamber into an upper
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~pace and a lower space at the ~ame time~ whereby
a channeling means serving to conneot the working-
atroke chamber to the upper space o~ the idle-
stroke chamber at regular inter~als i~ proYided ln
the idle-~troke chamber at that ~ide thereo~ which
faces th~ upper end face o~ the hammer.
It will be noted that in the disclosed appa-
ratus th~ hammer i8 accelerated during the idle
3troke, for the idle-stroke chamber i~ ~eparated
into an upper and a lower space and compressed air
is expelled from that space where it~ pre~ence
would ~low down the progres~ of the hammer.
The acceleration o~ the hammer on the working
~troke i8 higher than in the Xnown apparatus. ~he
hammer ~ aoted upon by alresultant force due to
the pre~ure Or compressed air in the worXing-~troke
chamber, which i8 connected to the compre~sed air
line at regular intervale, and the pre~ure in the
upper space o~ the idle-stroke chamber which is
formed by the cylindrical protuberance o~ the chip8-
recei~ing slee~e and communicates with the ~orking-
stroke chamber~ The two forces acting on the hsmmer
co~ncide i~ dire¢tion snd it~ ~peed on the working
~troko there~oro in¢rea~es.
Summing up, two ac¢eleratione of the hammer
occur in the discloeed apparatus, on the idle ~troke
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~6~454
3nd on the working one. ~here~ore, the frequency
and impact foxce of the strokes i~crea~e~ there.
It i8 expedient that the channeling means i9
pro~ided in the ~orm of at lea~t a single lo~gi-
tudinal groove which e~tend~ between the inlet portsof the case through a full-length ~troke of the
hammer.
Thi3 plan permit~ an optimum perfor~ance of
the ring-shaped hammer to be achieved in spite of
a limited radial extent of its working ~uriace. An
optimum relation#hip between the cross-se¢tional
area of the chann~ling mean~ and the volume of the
chambers which is established in thi~ case pro~ides
~or a minimum con~umption of compressed air~ ensur-
in8 economical operation ~f the hammer unit andthe apparatus as a whole.
Briei~ Description of the Drawing~
A preferred embodiment of the invention will
now be described with reference to the accompany-
ing drawing~ in which
Pig. 1 i~ a schematic cross-~ectional eleva-
tion of the annular air-hammer apparatus for dril-
; ling hole~ according to the in~ention, in a po~i-
tion when the hammer strike~ again~t the rock-cut-
ting tool~
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~ ig. 2 i~ a ~chematic cro~s-~ectional eleva-
tion o~ the annular air-hammer apparatu~ for dril-
ling holes according to the in~ention, in a posi-
t~on when the hammer i8 on the idle stroke and ar-
rive~ at it~ topmo~t ~tation;
Fig. 3 i~ a as¢tion on line III-III of Fig. 1-
Detailed Description of the I~Yention
Referring to Fig~. 1 and 2, the annular air-
hammer apparatus for drilling holes incorporates
~ a hollow ¢ylindrical ca~e 1 with a stepped bore.
A step 2 Or ~ smaller diameter locatad at the top
of the case 1 i~ pro~ided with inlet ports 3 ad-
mitted wherethrough irom a line i9 a compre~ed
ga~eous fluid~i and a step 4 of a larger diameter
15 whioh faces the bottom holle is pro~ided with outlet
ports 5. The case 1 is rigidly attached at its top
to an external pipe 6 oi a concentric string 7.
rock-cutting tool 8 with an axial chips-receiv-
ing opening 9 and blow ofi passages 10 i~ fitted
20 to the step 4 at the lower end oi the case 1 with
pro~ieion for a~ial displacement. Contained in the
bore of ths stepped ca~e 1 there are a stati¢ chips-
receiving clee~e 11 and a ~teppod ring-shaped ham-
mer 12 capablo of re¢iprocating ba¢k and forth
25 ¢on¢entri¢slly ~ith the ¢ace 1 ~o ae to form a
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i260~i4
working-stroke chamber 13 with the ca~e 1 and a~
ldle-~troke chamber 14 with the ca~e 1~ the rock-
cutting tool 8 ~nd the chips-recei~ing ~leeve 11
The chambers 13 and 14 alternately communicate
with the bottom hole 15 via the outlet ports ~.
The lower end 16 of the chips-recei~ing ~leeve
11 ~it~ into the axial chipa-receiving opening 9
of the rock-cutting tool 8~ and the upper end 17
of the chip~-receiving ~lee~e 11 i8 linked to the
internal pipe 18 of ~e concentr~c string 7. A
cylindri¢al protuberance 19 of the ohips-recei~-
ing slee~e 11 provided at the upper end thereof
interacts with the bore 20 of the hammer 12 when
thi~ arrives into its topmost position ~Pig. 2)
~o a~ to separate the idle-stroke chamber 14 into
an upper space 21 and a lower space 22 which com-
municates with eaoh other through an annular pas-
sage 23. ~he idle-etroke chamber 14 18 pro~ided
with a channeling means ln the form o~ a single
lo~gitudinal groove 25 lo¢ated in the cyl~ndrical
bore 24 of the step 2 o~ the case 1 between the in-
let ports 3 (Figo 3). Alternati~ely, a plural~ty
Or su¢h grooves 25 ¢an be provided for.
A ahell 26 ser~es to protect the apparatus,
e.g- it~ work~n4-etroke chsmber 13, against an
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lngres~ o~ chips. A pac~er 27 pro~ided at the bottom
of the ~hell 26 i901ate9 the bottom hole 15 from
L,he shell-borehole annulu~ 28 in order to induce
a flow of spent air from the bottom hole 15 into
the bore 29 o~ the chip~-receiving sleeve 11.
The fact that in the ambodiment of the inven-
tion disclosed hereinabove the cylindrical protu-
berance 19 o$ the chipa-receiving sleeve 11 at the
upper end thereof interacts with the bore 20 of
the hammer 12 and separate~ the upper ~pace 21
o~ the idle-~troke chamber 14 from the lower ~pace
22 thereof at regular interval~ and that the chan-
neling means i8 provided in the idle-stroke cham-
ber 14 at the side thereof faci~g the upper end
face of the hammer 12 to bonnect this chamber to
the compressed air line through the working-atroke
chamber 13 at regular intervals when the hammer 12
arrive~ into its topmost position ensures an ef-
fecti~e utilization of the area of the upper end
ZO iace 30 of the hammer 12 with the result that the
force~ acting thereupon during every operati~g cycle
sugment and the performance of the apparatu~ (i.e.
the frequency and force of strokes) impro~es and
its reliability in¢rea~es.
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12604~4
In operation, the compressed air fed over the
annular space between the internal pipe 18 (Fig. 1)
and the external pipe 6 of the string 7 is admitted
into the idle-stroke chamber 14 through the inlet
ports 3, whereby the working-stroke chamber 13
is connected to the bore 29 of the chips-receiving
sleeve 11 via the open outlet ports 5, the blow
off passages 10 of the rock-cutting tool 8 and the
bottom hole 15. The air admitted into the idle-
stroke chamber 14 acts on both the upper and lower
end faces 30 and 31, respectively, of the hammer 12.
The resulting forces oppose one another in direc-
tion. However, the area of the lower end fase 31
is larger than that of the upper end face 30, and
; the hammer 12 starts moving upwards (Fig. 1),
beginning an idle-stroke. As ~oon as collars 32 and
33 of the hammer 12 overlap the outlet ports 5 and
the inlet ports 3, respectively, the flow of air
~ into the idle-stroke chamber 14 is interrupted. In
- continuing on the idle stroke, the hammer reaches
the cylindrical protuberance 19 of the chips-
receiving sleeve 11 which closes the annular
passage 23, separating thus the upper space 21 of
the idle-stroke chamber 14 from the lower space 22
thereof. At the same time, the hammer 12 uncovers
the longitudinal grooves 25 which connect the
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upper ~pace 21 of the idle-stroke chamber 14 to
the working-~troke chamber 13. The air contained
in the upper ~pace 21 o~ ~ idle-~troke chamber
14 escap~ into the working-stroke chamber 13, and
the pre~sure in the two chambers 13 and 14 is
equalized. But ~ince the volume of the working-stroke
chamber 13 exceeds that of the idle-~troke chamber
14 three- to sixfold whereas the volume of the up-
per space 21 oi the idle-~troke chnmber 14 i~ be-
10 tween only 1/6 and 1J10 of the volume of the work-
ing-stroke chamber 13, the equalized pres~ure in
the two chamb~rs i8 slightly abo~e the atmo~pheric
~ressure and greatly le~s than the pressure in
the compreesed air mains. The air pressure applied
15 to the upper end faoe 30 df the hammer 12 and
hampering its progress decreases whereas the pres-
sure which the air in the lower ~pace 22 of the
; idle-stroke chamber 14 exerts on the lower.~nd
face 31 o~ the hammer 12 rem~ins unchanged. The
20 re~ultin~ pres~ure difference accelerate~ the hammer
12, e~abling it to complete the idle ~troke within
a shorter time inter~al.
Purther upward progreos oi the hammer 12 oon-
nects the outlet port~ 5 to the lower ~pace 22
25 Or the idle-stroke chamber 14 and the inlet port~ 3
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1260454
to the working-stroke chamber 13. The air contain-
ed in the lower ~pace 22 of the idle-~troke cham-
ber 14 e~capes, and compressed air is'admitted
into the working-~troke chamber 13 and.hen¢e,into
the upper ~psce 21'of the idle-stroke chamber 14
via the groove~ 24.
The air pressure ~et up in the two chambers
and spplied to the upper end ~a¢e 30 of the hammer
12 and the annular area ~ormed due to the dif~e-
rence between the diameter~ o~ the large-diameter
collar 32 and the ~mall-diameter collar 33 causes
the hammer 12 to stop a~d rever~e the direotion of
its travel, 3tarting a working ~troke down~ards
(Pig. 2)- As the ¢ollar~ 32 and 33 oi the hammer
~5 12 overlap the inlet ports 3 and the outlet ports
5, the source o~ the motive power of the hammer 12
i~ the energy of the a~r expanding in the working-
~tro~e chamber 13 and the upper space 21 of the
idle-~troke chamber 14. Continuing it~ downward
travel, the hammer 12 disconnect~ the working-
stroke ohamber 13 from,the upper space 21 o~ the
idle-stroke chamber 14 due to its collar 32 which
overlaps the longitudinal grooves 24 and connects
the Uppor space 21 to the lower space 22.of the
' Z5 idle-stroke chamber ~4 through the uncovered
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iZ60454
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annuiar pa~age 23. The pres~ure in the two ~paces
21 and 22 of the idle-stroka chamber 14 equalizes-
At the same time~ the inlet ports 3 are connected
to the idle-~troke chamber 14 and the outlet ports
5 to the working-~troke chamber 13. The ~ir contain-
ed in the working-stroke chs,mber 13 e~cspes and
compres~ed air enters the idle-stroke chamb~r 14.
The hammer 12 strikes against the rock-cuttin~
tool 8, and the rock broken of~ i~ carried to the
surface by ~ current of spent air ~ia the annular
chips-recei~ing opening 9 in the rock-cutting tool
8, the bore 29 of the chip3-recei~ing sleeve 11
and the internal pipe 18 of the concentric ~tring 7.
The regular ~epsrations of the idle-stroke
chamber 14 into two spaceb followed by the connec-
tlons of its upper space 21 to the working-~troke
chamber 13 are the factors whi¢h augment the forc-
es applied to the hammer 12 in operation. The area
of the hPmmer acting whereupon i~ compres~ed air
i~ expanded both during the work~ng and idle strokes.
Th~ speed of the hammer 12 increases~ and the pe-
riods of effecting the idle and working strokes
sre shortened.
~he disclosed apparatus compares fa~ourably
~, 25 with the known annular air-hammer apparatus ~or
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drilling holes, ~eatu~ing a 1 .5-fold increaee in
the fre quency of stroke~, high impact ~tre~lgth and
operstional reliability.
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