US1559709A - Rock drill - Google Patents

Description

M. A. KNAPP ROCK DRILL Filed Sent. 18, 1920 W xii l 2 Y l 63 I AIEA/volumi? I I l if W /f ATTORNEYS 6 Sheets-Sheet 1 Nov. 3, 1925. 1,559,709

M. A. KNAPP ROCK DRILL Filed Sept. 18, 1920 6 Sheets-Sheet 2 Mm mm Nov. s, 192s; h f 1,559,109

. M. A. KNAPP ROCK DRILL Filed sept. 15y 1920` 6 Sheets-snee?h s /Ml //Z 3.

2 ATTORNEYS MVG/2,27%,

Nav. 3, 1925. 1,559,709

M. A. KNAPP ROCKDRILL Filed set. 18) 1920 e sheets-shei 4 la ATTORNEYS W 1 TNESS' M. A. KNAPP ROCK DRILL Nov, 3, 19.25.

a ATTORNEYS w MN RVMQ ilim g w Vlll 1./ 1 Y wm\ Nm. N. v m mw NI A 1 Filledl sept. 18

v um... 'Nrw mmv hd.. ggg u i. fiiLif -i k A, W IlllvlHF//mzu IIYIIVNI I .INPK Hlwiisnutlldlwn" |rI11- Nov.' 34 1925.

M. A. KNAPP ROCK DRILL Filed Sept. L8. 192.0 '6 Sl'xeets--Shee'c 6 wmlmlml.

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, ATTORNEYS Patented Nov.v3, 1925.

UNITED STATES ROCK Application filed September To all 'whom it may concern.'

Be it known that I, Mosns ARTHUR KNAPP, a citizen of the United States, and a resident of Oakland, county of Alameda, State of California, have invented certain new and useful Improvements in Rock Drills7 of which the following is a specification.

The Vinvention relates to rock drills and especially to'drill rods used with hammer rock drills which are operated kby a series of heavy' `percussive blows delivered in rapid succession by a compressed air operated hammer. y

An object of the invention is to provide means for transferring a high percentage of the energy of the hammer blow of a rapidly striking hammering machine external to the drill hole to a light rock cutting drill bit' wholly inserted in the drill hole and free to move forward under the impulses 'of the hammer blows. A y

Another object of the invention is to provide means for aligning the' drill hole and Vfor maintaining it atp the necessary diameter.

A further object of the invention is to provid-e means fortalring al fairly consecutive sample of the rock cuttings' continuously from the drill holes to ldetermine the loca-V tion of ore bodies cut by the holes.

A further object of theinvention is to provide means for rotating the-.drill bits in the drill hole for inserting and withdrawing the drill rods and for sustaining them while drilling. A

A further object of the invention is to provide a new form of hammering machine whereby a plurality of heavy percussive .blows may be delivered in very rapid succession. j n

A further object of the invention is to provide a rock drill comprising a plurality of rods interposed between the drillV bit and the hammering machine with means for holding the rods in longitudinal contact so that a high percentage of the energy of each of the high frequency hammerblows delivered to the outermost rod is transferred through the rod series to the drill bit. The vdrill bit is generally separate from the energy transmitting means and is carried by a tube surrounding the rods and the `drill bit is mounted so that it is capable of longitudinalmovement independenty of the tube.

PATE-.N OSFHCif-y MOSES'ARTAHUR'KNAPP, or OAKLAND, caiiron'mn.

DRLL. p .y

1a, 1920. serial No. 4.114,064.` j

The invention possesses other advantageous features, some of which, with the fore-v going, will be set forth at length in the following `description where` I shallv outline in fulll that form of ther4 invention which I have selected for illustration in the. draw# ings accompanying and formingpart of the present specification. v have shown several embodiments ofthe rock drill of my invention, but it is to'be under In- 4said vdrawings I bodiments shown since the invention as set forth in the claims may be embodied in'a plurality of other forms..

Generally considered the'invention comprises a series of abutting rods enclosed in a tube or pipe and elasticallyheld in the pipel at the forward end or at both vends of the rod series, and very strongly held in vcontact at their ends by the tensile strength of the pipe; and a self-aligning,jself-clear-f ing drill bit loosely held at the forward ,y end of the pipe and adapted .toreceive the impulses transmitted through the' rod seriesv from the rapidly reciprocating hammergarranged external to the drillho'le; together with means of collecting consecutively the sample cuttings and of rotating and.. handling the rods and pipe sections and other I accessory apparatus necessary to the oom-` plete operation.

Referring to said "drawings:

Fig. 1 isan elevation of the general arrangement 0f the drillingapparatus in aA mine drift when. drilling a slightly downcast hole. f Fig.2 is a plan view of thev hammerdrill on its shell showing the means for handlingl the rods.

Fig. 3 is la section taken on the line'3-3, Fig. 2.

` Fig.` 4 is an elevation oftherod-pulling clamp.

Fig. 5 is a longitudinal section of the rodpulling clamp. l

Fig. 6 is a longitudinal'se'ction through the ydrilling machiner showing the reciprocating hammer. f

Fig. 7 is ahorizontal section through the hammering machine showing the tappet and the end rod of therodseries, and showing an outlet for the sample'fromthe drill hole.

Fig. 8 is a plan and partial horizontal secy i of tion of a portion of a hammer drilling machine in operative position against the rear rod of` the composite. drill: rrod showingv means for rotating the rod tube by-liands Fig. 9 is a longitudinal lsection througha portion of a drillingmachineshowingthe outlet for the sample from the vdrill""rod through a swivel in front of a self-rotatinglg hammer ldrill adapted to rotate the composite rod series by power.,

Fig. 10 is a longitudinal section of a modified form; of` tappet adapted eto. enter.. the yfront endof a standard hammerdrilling machine (and to be used infcoiinectioiiwith.V handirotation. of the rod allowing the drill chuck:7 toV rotate freely.

` Fig; l1 is an elevation of the end of the drillingmachine showing means to. connecttherodsand the drilling machine. t

Fig. 12 isV an elevation of Ythe yolie used in. the structure shown in" Fig. 1l.` i

Fig. 13 is a longitudinal section through.. one section ofthe composite drill fiod.' l

Fig. 14 'is .a` longitudinalsection through the composite drill rodshowing a plurality.. of Vrods in series,'thedrillrod .being'fbrolien away at parts tliereoffto reducethelength ofthe gure. i i

Figi` 15k isa cross section taken on the. line 15 15, of-Fig. 14.

Fig. 16 -is a cross section taken on the. line 1li-1G. of Fig. 19.

Fi l? is longitudinal.section through a reaiiier for use in c'onnectionwith the roel: drill of my invention.

Fig. 18 is across lsection taken onthe line isie, Fig. i7. 1

Fig.v 19 is a longitudinal section on a laigeifscyale of. a connectionmeans betweenV the tube and the forward :rod Yshown in' Fig.

20 is a longitudinal section of the. drill bit of my invention.Y f

Fig. 21is a plan View. of the drill bit of my inyention inserted' in vthe, rod tube.r

l QQis .af yiew of the. cutting face of: the drill bit of my invention. 23 yis an eleyationr of'a modified form :drillbit Fig. Q4 is a cross section of the bit shown 23.: l v i is an elevation of the cuttingend yliedrill bit shown inF-ig; l Fig. 26 is a front elevation of the forni ci drill bit` shown inlig.

Fig. 27 is a longitudinal section of, Va portion of.v the feel cylinder,` sliowingthe. air conduits and control Valve. v

Fig. 28 is a longitudinal section through the drill tube `showing the.r drill; secured thereto by a rubber filler.

The; cl: drill -of my invention comprisesdiilliug engine of the hammer type a drill: bit wholliY inserted in the drill hole and energy.4 transmitting means interposed .ybez

tween the hammer and the drill bit for transmitting the energy of hammers blows to the drill bit. The energytransmitting means comprises va composite drilling. rod

compose-dof a plurality of sections of pipe or tubing securely fastened. together and a plurality vof rods" disposed in longitudinal er i e iient within the pipe. The drill bit is car ed by aiidi'otated by the pipe and lie.iinpac t offtheihaminer blow is transiiiitted freni the hammer to the drill bit through the rod seriesinithep-ipe. Therods in the series. are.v in tighti abuttingengagef.

ment. and the eiidiof the leadingrod is in.. Y

abutting. contact withthe. shank; of thesdrill ait,v so .that the..y energy o f the ,hainnier blowv is transmitted tothe drill bit with the, .minimum energy. loss.. "llhepipfe andf'rodsarc.

formed in .sect-ions, and additional sections.

are addedto the vcomposite.` .drillirodfas ithe drilled.y hole .,`deepens, rendering .1. thev dri-llt particularlyadaptable Y to they formation.of.l deepy holes. Eachs'ection.preferably; Coniprises. a pipe Ysection.and.a contained rodfsection of the saine length the pipe section, so thatwhen acompositeisection isfscreu 'l inv placefthe rodfin tlieadded sectionAAV is. brought into tightabiitt w ends of the. radj lacellt .'rods. Thel Vaiioiisicojinf. positie rod sections are preferably. ofdiiieient.- forin,`as;, willl behereinafter set forth.

. Contact. with in Fig.:V 14, 1 have; shown a composite drilling rod formed of four sections,al-

though it 1 is to. .bev understood l.that l de` i sired number. of sectioiisinay be employed,... dependingl upon the!depth'v ofcthe:y hole.`V

i/eans are provided. Within the Composite rod .f forv holding the., rod sections.v pressed tightly together under heavy pressure, so.

that thevibifationof ,the-rods. due to the rapidly recniji'ing.hammerv blows, will notl cause the .rods .tosepaiate. Tlhi'eiodl-sectioii in theL outer composite sectionusually placedv ,longitudinally ,.by the `contiguous rod l section, thus indicating tha-tall ofthe rod sectiens arefin pressing.Contact.l The vlead-i ing rod sections are firmly and resiliently held to Uthe containing pipeJ sections and these; Sections aredisrled Slight-lr lonel-L tudin:illy` when the sections are screwed together vthus placing they entire rod series under longitudinal.pressure.

Ther leadiiiglpipe section 21fcoinprises a socket for the shank 22.of the drill bit 23 which. has a limited longitudinal` motion. withv respect to lthepipeito* permit the drill bit to spring forward againstfthe face of they rock7 under the.transinitted impulses ofthe hammer. Firnily and tightlyiscrewed to the pipe section 21 by anipplejis the second, pipe SeGtQaQ. in. Whehis. disposed.;

a rodv section 26 which is resiliently heldto the pipe section so that it is capable of longitudinal vibration, withoutl permanentv longitudinal displacement. This rod .section, which l have termed the rebounding rod section, springs forward from the fol-i lowing or contiguous rod section, under the impulses of the hammer blows, and strikes andimparts the energy of the blow totheA drillbit. The rod sectioninay be i'csiiiently held to the pipe section in any suitable manner, such as bythe introduction of a cylinder of rubber 2? into the annular spaoe between the rod and the pipe; The rubber is introduced into the annular space in sucli manner that it is under pressure-and in tight contact with the rod and pipe, permitting the rod to move slightly with respect to the pipe, but preventing it from Vbeing permanently displaced. Y The rubber maybe in the form of a cylinderor may comprise a strip of rubber wrapped spirally around the rod or may comprise longitudinal strips or may be otherwise suitably formed and inserted, as' will kbe hereinafter s et 'foi-th. I prefer to use rubber, rather than a metallic spring, since the rubber will not transmit the vibration of the rod tothe pipe and since the rubber will remain live under vibration, whereas metal may crystallize.

Secured to the pipe section 25 by the nipple 28 is another pipe section 29 containing a rod'section 3l which is held rmly andy resiliently to the pipe by a rubber retainer 32, of similar constructionV as the retainer 27, orvinore strongly made so that it holds l the rod more firmly to the pipe. This rod section I have Ytermed the rubber heldsection, in distinction to the rebounding section 26. The rod section 31 is held so firmly that while it is capable of longitudinal displacement, the pressure tending to return it to normalposition is so great that l there is no relative movement of the rod section 3l with respect to the succeeding rodsections of the composite rod. In some instances, it may be advisable to employ twol rebounding rod sections between the rigidly held rubber held rod 31 and thedrill bit, but in most instances, one rebounding rod section is sufficient. composite rod comprises combined pipe and rod Vsections 30, the number used depending upon the depth of the drill hole.

in handling. Y' The outer section ofthe coinposiie rod, usually comprises a pipe section The remainder lof theot rubber or other conformable or re 37,-afrod section 38 and a rubber retainer 39 `inserted and compressed .in the annular 'v space'between the rod and t-liepipe. 'The rod 38 is firmly held in the pipe in substantially the saine degree asthe rod section 3l,

so thatwlien the pipe sections are screwedl togethertightly, the rod section 38 will be a,

displaced vlo'.aekiwrdly to the same extent as the section 3i is displaced forwardly, thereby indicating the pressure with which the rods of thesei'ies are held together. It is advisable that this ,pressure be suoli that there is no separation of the rods during the operation of tlieliammer. 'Means other than the rubber insertion may be usedfor extends fromthe pipe 3T at'the rear, and is providedV with an upset head 4l -which is y.held in iirni contact'wit-h the tappet 42 of the drilling engine.

The forward section 2l of the'coniposite drill rod is provided with a bayonet slot 43 in which a lug 44 on the shank of the drill bit 23 is disposed. rllie slot is longer than the lug so that the drill bit has a free Vholding the rear rod pressed forward, as will Y be setforthhereinafter.` rlhe rearrod 38 a longitudinal lmovement with respect to the pipe, but is at the saine time rotatable with the pipe.

securedto the rear length of pipe, as shown in Fig. 8, or may be rotated by power oper- The pipe may be rotated vin any suitable manner, vsuch as by the handles 45,v

ated means, as will-be hereinafter set forth.A

ln operation, the drill vlcit 'is' held close to the' face "of the rock being cut and the pipe is continuously rotated. i Fitted into thel drill hole at the outer end is a 'flanged bushing 46, through which the l composite drill rod extends and with which it formsa turning fit. Air and water under pressure are entered into the drill hole` at the bushing for the purpose of keeping the lhole clean and tlieair and water flowsV l through "the space between the pipe and the drilledhole tothe drill bit and in high angley holes is flowed'inward throughtlie i hollow rods. For the purposeofremoving the Adrilled rock and obtaining vfairly consecutive samples, of the rock .cut, tlie drill bit is provided with ai passage 47 opening on the `side of thefbit adjacent the cuttingv1 "facefand disposed axiallyvof the shank. ofl

The Vrod sections are hollow, formthe'bit. ing a continuous passage 48 through the composite rod series for the discharge of the air, water andk cut rock. The. upset end 4l of the rear rodV 38 seats in the tappet 42,

which is pi'oyided with a saiiiple'exit passage 49, one end of which opens on thev end` of the tappet in alinement with the passage 48. A sliortrubber nipple "lforms a con-y nection betweeny the passages 48 and 49. i

At its other endtliegpassage 49 opens on.

the side of thetappetfandis connected by a short rubber nipple'52 with the discharge conduit,k 53, secured toftheishellj. 54 oi the drilling.4 engine. Theitappeteis :heldA pressed 'crvmrd zigsinst theendrod; h-yn spring,

55 .endsis=vihreted..or. reciprecrited4r longitudinally hy the hammer et the.drilling;

enginey The, shell 54- is i provide-d with y an enlztrgedlpocliet suHound-ingI vvthe nipple 52, toV permit the nippleto movefleteie-.lly freely es the tappet'endnmchine are `sepa-- rated the. herinner vibrations.

ln Fig. 9,1 havehown e inodiiisd. forni c'l inerme-.for rotating. the dri-ll rod-tend e1;- tizretin tir. ip le. ln this .construetionrodisection 23S/is provided with :i ensien 5? which entendsinto rotary e piece 58 otfthe-drillingqenif e; the rodheing provided-.with s. lngg) vv.hieh engeges .sislet in the-clinch pieeeso ded v-.nithe thickened orupse't portion 611 sage/i8 in the rod, terminates Tini. this `poi'-` tion in coi'nninnication withV the-transverse passe-ge 62g opening; on the side of-.the rod',

und. the surface of. the. rod, to

SeXtends is beveled tocorrespondtofth'e bevel.

4 on the enlarged portion .ottherodend a spring 68 is interposed.'between theshelL ot thedrillingengine. and thecasing, to hold= the rod ser-ies vpushed forward and away 40 lronrthe drill-ing engine.. The .ruhher con.

e nection bctweenthefrod Vand' the surroundinpipipeis not. sufficiently strongto be re-` lied in continuous operation, to transmit therotary motion of the rear rod to the ,pipe rindy for ,thisA purpose, :they lrod l:is` provided.V

with' a luglseafted inaslotTQfin the rear, pipe section, s

Secured', .tothe reenpipe. section are two spaced rings 73-74 between which isdisr.

.posed a lloiosethrust hearing and the ineens; for insertingend removing Athe coni-V posite drill from thedri-ll hole engages between one oi the ringsfand thel thrust bearing,K depending., upon Y the direction Iof niovei inentfof the composite drill rod.

The ,hammer drilling engine Z6-is mounted Yon the erin 77 of n drill coluinnfS', to which it is held by the clampv 7 9. The composite drill' rod, extends v'rorn the", drilling 1 engine .into `the drillhole, KthroughV the air tightl bushing m46.' Coinpressedeirfis supplied. to thenpperatushy the pipel, which is connected to the drilling engine, to the cylinder,

for handlingwthe rod vseries and tothe Water ..tenk 82, fronrvvhich Water under pressure i that it lrotates therewith.. The rodBS isfpro-VV iacent its rear end and the longitlidinnla chamber andivired down totheI therod is e rubherflange ring.; the `iointsbetween tl1eAvalls oi.

The aperture in they rear fiows into theedrilll.holesA The sample,withVr its mixed eaters sfdiseharg/ed ffromethefrods.; through i the ,f conduit 3 into. ..thefszirnpl'e'TrefA ceivingY snel; 83 frommhich, theweterfdreins.; T he bushing, et@ et the; n'iouth., fot the drillf 70 hole, is screwed` to, 11...-shert-.vlengr'h otY pipe 1 Slet .iinedsecurely und tightly`v inv the enlarged. inouthoi thedrillflholef. l l

The drilling engine 76..is mountedv onffthe drilli shell ieross .the (nidsl ot fthe Y shell r 75 are. .boltedtwinKV pla-tes; 85. rand r8.6.,- betweenwhieheis fastened etstetinnzri piston. rod il 7^ ecipgeeutes deylinderh88-i over apistensecuredIto the pistonyro nir; is uppliedrto Abotl,ifends fofthe cylinder in trontoic endfinihaclnot lthe,:pistonthrough4 conduits 91 ,en-.d 92loneof.theonduits .cone nectin x ith. :i passe-ge 93 rextendingthrough ther pistonied.` .and opening.; in front ofv the, piston, the. ,otherU` conduit. opening ,pinto .85. theylinder in heck' of the piston.. The icone. duiitds .secured by, si,packing,d ring 193 l to .the f startinner-ylv pistonA .rod ,187,1 which".l is.. providediviih ports; 194T1l95 von opposite sides:l otf the .,ringg 1933 to y-perfrnit; .the .passa-ge 90. of sirinto thefcyli'nde'r SSoneither.sideotjf the piston 89 which is arranged in. the. same pleinesfis.,-thefringg`l93 The. conduitsnfl and 32 lere iconnectedfto the coinpressedfair p supply pipe. 8l .ande ,our-.Wayvalv'fe 1961' is arranged 'inwtheconduit to fcontrollthe.; introduction; otfand "discharge of fair' from... th e. cylinder.;. The cylinder `Uis Afthus. movable. longitudinally over the. iixedfg'pistonrod-jvr Secured 'to the cylinder preferably Eloy-.Weldinguaretwonngle irons 94f95nnd sli'da'hlel betweenthe angle', ir'onsise` channel 'ironVA 9G Whic'h'rinay he secured ftothe `angles in adjusted 'position bypins orholts-Q extending through ,seats 98 "in-.the angle' irons andIapertures in the `@henne-l iron. Inithis mannen the position ot the channel with respecte to the snglesfiniy he variedizis desirable toproduce a inoveinen-t'ot "the chen'- nel-of greeter extent than the stroke of .the cylinder.A

Detachnbly secured to the channel iron at itsforWard--endfis an arm 10.2"lia-vingen.Y hifurcated ,-'endxsdaptedlto 4enga-ge the. outer pipe section between the rings73#74 thereon 'ofr the purpose of ymoving Vthefcornposite rod:v longitudinally.v In the' drilling operer-VY tion the composite'drill'rod is edvancedfintoV the-hole' and thebt held ,up to the Work by adinittingeir into the cylinder-,in front of the piston; This device 'is also used for inserting the composite rodvv into andre- .moving it from a steep angle; drilllhole ivhich'has already4 been started and which:

may be of considerable"depth as set VJforth .below Means 'areprovidedv-ffor pulling the 'coinposite rod troni' vlthe drill 'hole' when.l `necesseryor desirable.: yTo accomplish this the drill shell is. shifted laterally on the arm dog 106.

77 to bring the piston 88 into substantial alineinent with 'the drill rod. `The arm 102 is then removed and inA its place there is attached a block 103 having an arm, 10-1 pivoted thereto and adapted to be locked there-` to by the bolt 105. Swinging from the arm 104 in a slot in the block is a spring held` The composite drill rod extends.v

through the slot in the block and on the .forward movement of the block theA dog does not engage the pipe, but on` the backward lmovement of the block the dog grips the sive blows in rapid succession., In the drawings I have shown a valveless hammer drill since'I am of the opinion that thisl typel ofV drill is preferable for use in connection with ,I

the drilling apparatus of my invention, but it is to be understood that I do not limit myself to the use of` a valveless hammer drill. Y

In Fig. 6, I have shown one form of valveless hammer drilling engine which is particularly adapted for use in connection with my invention. This hammer drill comprises a cylinder 112 in which there is disposed a differential piston or hammer 113, thepiston is provided with piston rings forming a tight joint between the piston and the cylinder and these piston rings 114V are simple flat rings breaking joints in the ringed Y groove. YThe piston is provided with an eX- .f

tension 115 of rlesser diameter than the body of the piston and this extension forms the hammer which strikes against the tappet. The hammer A115 forms a tight sliding joint in the shell 112 and piston rings 117 seated in the shell and engaging the face of the extension form a substantially air tight joint. The cylinder is divided into two parts longitudinally by an annular wall118 which forms a cushion plate. The piston is vprovided with a bore 119'into which the cushion tube 121 extends, the vtube being yopen at both ends and being secured at its rear end to theA wall 118. Piston rings A122 cylinder, permitting air under pressure to pass through the passage '123, bore'119 and tube 121 into the reserve air chambery125 behind the wall 118 and into the chamber 126 behind the piston, through the apertures 127 in the tube. This forms an air cushion, protected by piston rings 1.14; `and 122 and Vthe air cushion catches and rebounds the j piston. The area ofthe rear face of theiplston exposed to air pressureis greaterthan the area of the front face 0f the piston eX- posedto air pressure, so that vthe piston .is

ward, the compressed air in theyy reserve chamber 125 enters the cushion chamber 126, and accelerates the forward movement of the piston. .The advantage Ofthis construction lies in the very rapid rearward. movement of the piston due to the large front shoulder on the piston combined with high speed of forward movement due to both the perfect rebound due tothe aircushion and the 'eX- pansion of the air in the reserve chamber.

vAs the piston approaches the end of its fore ward movement, and the hammer 115 is in close relation to the tappet 128,. the passage 123 opens into Vthe exhaust port 129, permitting the air behind the piston to exhaust. The*r wall 118 is'provided with a check valve 130 to permit the flow of air from there*r serve air Chamber 125 to the cushion chamber 126. Thecheck valve is more of a precaution against sticking of the hammer or worn piston rings, than a necessary element in a well designed hammer.

In Fig. 10, I have shown the. front end of a hammer drilling engine not adapted'to rotate the rods of this drilling system.- The tappet 4.2 is provided with a sample discharge which extends directly from the headA of the tappet in front of the drilling engine so that the chuck may be' rotated without interfering with the discharge of the sample. The rear ,section of pipe 37 is provided with a seat or pocket 131 inwhich a pinor .lug 132 on the rear section of drill rod 38 is disposed. The tappet is heldl forward against the rear end of the drill rod by a spring 133 and this ,spring is secured to the tappet and to the shell ofthe drilling 4may chine to prevent 'rotation of theftappet byy the rotating chuck 0f the machine; v f In the construction shown in Figs. 11iand 12, I have provided ayoke piece 135 which fits yover the sleeve on therear vend. of the;

thrown forward.- As, the piston moves forso,k

compositerod between the rings 73' and 74 thereon. Two rods 136 are Vrigidly fastened f to theyokes and these rods pass through they front head 137 of the' drilling engine, springs 138 are interposed between the rear yends ofi the rods and the frontk head andpull the yoke vand rod back against'the machine. This yoke is used as will be hereafter eX- plained in connection with a reamer or rubber held'drill bit to hold the rods elastically against the machine whentheyare not supported as bythe contact yof the drill bit against the face of the rock. If quite long and properly adjusted springs are lused on the yoke and the vibration of the machine is Y.

ffthefpressure cylinder '88 to support thev` vWeight oflthe ro'dsin f rather @high angle doivncastlholes. Similarly in drilling-up-A cast holes it a long spring is used to'hold the yoke f. piece forward it may sustain considerable Iiveight ofl the rod f Without Vallowing the vibrationot the machine to interfere Vmaterially with drilling.

` ln F'gs. 20, 21i1rd 22,21 have shown a -Iiform of -dri ll{bitwhich is fp articularly -adaptedior use in connection with the drilling'systemfof my invention. The drill bit has a round shanlr22 having a passage l141 extending axially therethroil-gh aiid being deflected at the forward end of thebit to open o-n the'face of the bit. toone side thereo'f.- The shanlrincreases insize at the base otthebit andis provided Witht'ivo cylindrical Steps143a`nd 144. l he 'front end of the elongated head is cruciform in shape for about'tivo incliesback Aof the'tip. Back of ^that"thr`ee ofthe-grooves ofthe cruciforin shape continue `JorI thelengthlo'f the bit, but 'the iourth groote is filled level across as shown at 1545,-Fig- 22, the'pasage 142fin ythe'bit extends through this ,filled in porrti`on1145 and opens on the face of suclrporjtion abOuttWinChes'back ot' the jtip'o'f the bit. In order toprev'ent the clogging of the opening offthe passage 47 by the drilled material, a plurality of openings `146 are 'provided on the side of "the drill bit and ytheseopenings communicate with the passage 47. The tvvooribs of the cruciform" end oflitheVE bit opposite the passage y47- and opposite. the {ile'd in-portion '145 are provided on their' vends with 45 degree vinclined 4V yshaped.cutting edges 147, the othert-Wo ribs en d in practically` square cutting-edges 148 `'Wliich are positioned at about the Abase of the inclined cutting edges. The lbit head may be straight and parallel .vithgthe shank or maybe slightlyftapered to be of slightly less Width at the rear end. 'The Jio'rvzard pipe Asection21 is counterboredso Yas 'to ifit loosely about-the cylindrical steps 143 and Y fthe'arms or extensionsf172 yandareltorced outwardly ,the pointed rods.V `Inserted 1144, thus supporting the 'oscillating bits in all ,positions even lfatter thelpipe section 21 InFigsfQ-S and 24, I 'have shown amodi- Vtied 'form of drill bit which is in general similar to that showen in Fig. 21, with the lexception that its f tWo sloping cutting `edges lj-lfare made materially Athinner and are fboundedfby generally parallel'planes atthe opposite sides oftsuch edges. "The purpose of this shape of bit/edge -is to retain ahigh cuttingspeed until the Whole wedge is wenn roti". The result is only obtainable by special steel land careful temperingfand 1is applicable in this form of bit sincrethe ,outer portion Vofthese.cutting edges do ,notream the drill Jholesdas do the oblique edges ,ofthe points et 4the ordinary cross-bit. VtBy'matlringI Athe cntting edges narrouv they:retain-.theirsharpness u'ntil they are Worn dovvn and vare not f blunted rapidly as are-the cutting edgesA oi theordinary cross bit. These two cutting Aedges-are'joined at the point o'ithe bit in a rather smoothv curveand the otliertuto ribs :ofthe bit are provided with the square cuttingedges as described in connection with ythe bitshown infF1g.--2l. The Voblique cutting. edges are preferably Vbrouz'ghi'; Yout' as AWinding a*r Astrip of rubber v164y spirally-'about l the rod. This rubbenis under compression *and* permits the j rod' to move slightly longitudinally 'with respect to the pipe but 1 prevents any permanent displacement of Athe rod. 165 ltoa forward pipe section-1:66 Within which are arrangedfthe Vlaterally movable .cuttingblades 167. he pipe section 166 hasgtWo diametrioally opposedslots' through Which'the cutting blades lextend. Ehe forward end `of Vthe pipe section 166 is strengthened and reen'torce'dby tivofhalfround sections '1168 vfitting into the endetl the section on opposite sides '.oi" the cutting `bla-.des 1.67. 'The' cuttingblades are provided With thin spring steel'extensions 172 Ywhich are'turnedoutyvardly attheir ends and are Secured'in holes'in the sides'ofJthe pipe section 166. "The .cuttingblades are thus re- .siliently mounted and a're'free'to move outwardly under theection of'theinclined end 163 ,of the rod 162. The lcutting'bladesare normally held inwardlyby the .resilie vot :between the extensions 172 and the. pipe are rubber strips 17 3 Whichactfzpartly as springs 'Ehe-pipe ,161 is secured lby anipplef but merely vibrates longitudinally under such blows and since the inner sides ofthe cutting edge of the cutting blades 16'( are substantially parallel to the inclination ofV the pointed end 163.y it is apparent that longitudinal vibration of the rod lf 2 will cause lateral vibration of the cutters 16T.

When desired the drill bit 23 may be se-` cured to its surrounding pipe 2l by rubber 21a under compression inserted between the. shank of the bit and the pipe, so that the bit is allowed to oscillate from one-eighth to one-quarter of an inch longitudinally under the hammer blows as delivered to it by the rebounding rod of the rod series, as show in Figure 28. y

In Fig. 19, I have shown a modified method of securing the rod'to the pipe by means ofthe inserted rubber piece.` In this construction a short length of rubber cylinder is wired ,down at one end to the rod and inside of the other end of the shortrubber tube a thin hard steel ringVK 176 is inserted. The outer steel tube or pipe is then sprung or swaged down over the rubber about the rin 176; This forms an extremely elastic bond between the rod and the pipe through the rubber so that the rod may not be permanently displaced longitudinally with respect to the pipe. the ring, and the pipe touching the rubber are preferably roughened to increase the bond between the rubber and the metal. One or more of these rubber connections may be used between the rod Vand the pipe, depending upon the strength of bond that is required between the tube and the rebounding rod.

The action of this drilling apparatus is l substantially as follows: The rapid blows of a heavy hammer in a modern hammer drilling engine when deliveredk upon the rear end of a rod series such as shown cause the rods to jump apart unless they are very strongly heldtogether and such jumping apart rapidly lowers the percentage of energy of the hammers blows that can be passed through such rod series.V For that reason, by screwing the pipe together with a'slightly greater total length of enclosed rods than that of the pipe, I extend the rubber bond of the rear rod and the front strongly held rod or both of them to produce a compressive strain on the rodseries and I have obtained good results with a pressure of about 2000 pounds on the rod series.

With very light hammer drills striking slowly, that is about 600 per minute, it is possible to hold the rods effectively together by a forward pressure external to the drill hole forcing the bit against the rock. With modern high speed machines-striking very The surface of the rod,

heavy blows 2000 to 3000` pery minute-,a very high pressure on the rods is absolutely necessary for effective work, which pressure' is far too-great to be sustained by thefrotating bit point against the rock. Such pressure of the bit on the rockwould make impossible its effective rotation and would cause it to dullvery rapidly. l In practice with this apparatus the bits are normally rebounding yquite free from the rock andcutting at least four times as fast'as if pressed continuously against the hard rock. The blows of the hammer so delivered upon the rear end of the rod series cause waves of compression to Vtravel forward through the' rod series. The`A rebounding rodv is held elastically. against the strongly held rod by its rubber bond and Y generally under a pressure of less ,than 500 pounds. These advancing waves of compression cause the rebounding rod to fly off` .from the strongly held rod with a velocity representing a high percentage of the energy of such compressive waves.

By proper Vhandling'of the feed screw of the machine, the bit, rebounding from the rock face, is caused to be so close to the for-A wardfend of the rebounding rod that its motion is not over le of an inch or thereabout before it strikes the nearly equal length of drill bit. In this impact over'95 per-cent of the VVenergy lof the rod is transmitted to the V,bit ateach blow. With only the short distance of l of anlinch to. return, the rod is at rest f i against the strong rod at the time of the ar-y -rival of the next compression wave.

The tappet is elastically held against the outer rod partially in order to avoid -loss of 'energy by impact between them, also the springholding forward the tappet or-the` vrod and the spring actingqto hold the rods away from the drilling engine act to eliminate any vibration ofv the drilling engine` and to hold theV rods elastically vforward against the'spring action on the rod series of the rebounding bit and shank. This elastic support of the rod seriesand bit between the rock and the drilling engine is veryimportant in securing high drilling speed. AIn

high angle holes the air pressure cylinder anditscross arms are used to support-such the feed screw motion to freelyfadjust this pressure of the rods againstfthe bit and the i I i ltio'n'also throws the shovel or square.` edges of the bit into the angle of the hole cutting portion of the weight of the rods as to allowA out the small shelf of oversize carried by lthis bit. The thin edges of the bit shown in Fig. 23V when vrworn down half their height are still cuttingas fast as when only the yfirst lg of-an i'nch'hadbeen Worn off them and c'ontinuegat the saine speed until Worn out.

VThe -V shaped Yedges on the bit shown in Fig. 20, on the contrary, cut slower ask they Wear back.A

The oii'set bore hole ot the drill bit head is of importance since it allows the Working over of the metal of the ribs 'on-this side to supply tlie'wear of the edges on the other side.Y

In vremoving the bits from the drill hole VWhile the lioleis short, they may be pulled out by hand. Vil hen pulling long composite rods the'drilling engine is slid 'along the column bar'to alinement with the rods and the lpulling clamp is then used to. remove the rods troni the drill holes.

vWhat-is claimed is:

l. In a roclrdrill, a composite drillrod comiirising a tube, a rod disposed Within 'said' tube and means elastically holding the rodi-toithe tube. n y Y 2. In a rock drill,'a tube, a rod elastically held Within said tube, a drill bit carried byfthe ytube and a hammer associated With' tudin`al engagement insaid tube.

r5. Ina' rock drill, a composite drill rod icomprising a tube and aholloW rodV elastically' held Within said tube.

I6; lIn a Vrock drill,A a composite drill "rod comprising a tube, .a rod disposed Within "said "tube and elastic material interposed between therod and the tube Wherebf,7 the rod has limited longitudinal movement with 'respe'ct vto the tube.

7.111 a rock drill, a composite drill rod vcomp'rising -a tube, a rod Vdisposed Within 'said 'tribe and elastic rubber interposed be- Vtween"and forming an elastic connection be- 'tween the rod 'and tube.

8. In ka rock drill, a compositedrill rod i'coiuprising 'a tube and a rod 'ot substantially )the same 'lengthas the tube, elastically held i @as Within 'sa-id'tube.

'9. fIn, a rock drill, a composite drill rod comprising a tube and a hollow rodoi:A substantially vthe saine length as the :tube elas- 'tic'ally held Within the tube.

10. In a rock drill, a composite drill rod comprising a tube, a .drill bit arranged at the front end of said tube and capable ot vlon'gitudi-na'l movement vWithresvpect to the .tube and 'a rod cooperating with the drill bit andelastically held in said'tube. 1

lll. In a rock drill, a c )inposite\cliill rod rcomp'risir'ig a tube formed of tube sections secured-together, a rod of substantially the san'ie length as each tube section disposed in each Iection and means roiA holding the rods in tight longitudinal engagement.

l2. ln a roel; drill, a composite drill rod comprising a tube torn'ied oi? tube sections secured togetlier,'a rod ol substantially the same length as each tube section disposed in each section and means Within the tube ifor holding the rods in tight longitudinal engagement.

13. In a rock drill, a composite drill rod comprising a tube i'fornied oit tube sections secured together, a rod 'or' substantially the same length as each tube section disposed in each section means elastically holding the rods against longitudinaldisplacement.

let. ln a rock drill, a compositedrill rod comprisingl a tube formed ot tube sections secured together, a rod oit substantially the same length as each tube section disposed in each section and means'within the tube elastically .holding` the rods against longitudinal displacement. n

15. In ai rock drill, composite drill rod -comprising` a tube formed oiivtube sections secured together, a rod of substantially the same lengthas'eachltube'section disposed in each section and means elastically holding the rods against longitudinal displacement and in tight ylongitudinal engagement.

16. In a rock drill,a composite drill rod comprising a tube, a series of alined contiguousirods in 'said tube elast-ic'ally held to s'aid tube and a rebounding rod associated with said rod series.

17. In a 4rock drill,`a composite drill rod comprising a tube, a rrod elastically held in said tube adjacent the front'endthereot, and a rod seriesf'elastically heldin said tube' behind and in contact With said rod, the v'rods in the rod series being in pressure Contact. 18. Ina roclrdrill, a composite drill rod comprising` a tube, a series'of alined contiguous' rods insaid tube, means 'for holding` said rods in pressure contact and an elastically held rod associated with said rod series. Y

19. In a roclrdrill, 'a composite drill rod comprising a` tube, a series of 'alined contiguous rods in said tube, meanstor holding` said rods in pressure contact and substanti'ally lined with respect to said tube and an elastically lield rod engaging the forward end of said rod series.

` 20. In a rock drill, a composite drillrod comprising a tube, a series 'ot alined lcon.- tiguous rods in said tube, means interposed between the rods and th-e tube 'i'or holding the rod series under longitudinal 'compression and an elastically heldrod'engagingthe forward 'end of said series.

2l. 'ln a rock drill,'a composite drill rod comprising a tube, a series of alined convtigi'ious 'rods in said tude, means 'interposed between rvthe rods andthe tube vfor holfding the rodi series under longitudinali compression and; ior'prev-enting substantial longitudinal'l movement* oi the rod'sfand an elasticallyheld rod engagingj the forward' end-v of'said series.

22. -I'n a rock drill, aA compositedrilli rod comprising' a tube, a seriesr or" alined contiguous-rods in saidtube, n'ieans for' holding the rod series under longitudinali pres'- sure and a rubber-held rod engaging the entlottlie rod. series. f

23. In a rock drill, a composite drill rod comprisingy a tube, a series oi alined contiguous rods in said tube, means for holding the rod series under longitudinal pressure, a drill bit arranged at the end of the tube and an elastically held rebounding rod interposed between and cooperating with the rod series and bit.

24. In a rock drill, a composite drill rod comprising a tube, a series of alined contiguous rods in said tube, means for holding the rod series under longitudinal pressure, a drill bit arranged at the end of the tube to move longitudinally with respect thereto and an elastically held rodinterposed between and cooperating with the rod series and drill bit. i

25. In a rook drill, a composite drill rod comprising a tube, a series of alined contiguous rods in said tube, means for holding the rod series under longitudinal pressure, a drill bit arranged at the end of the tube and a rubber held rod interposed between and cooperating with the rod series and drill bit.

26. In a rock drill, a composite drill rod comprising a tube, a series of alined contiguous rods in said tube, means in the tube Jfor holding the rod series under longitudinal pressure, a drill bit arranged at the end of the tube and an elastically held rod interposed between the rod series bit.

27. In a rock drill, acomposite drill rod comprising a tube, a series of alined contiguous rods in said tube, -means for holding the rod series under longitudinal'pressure and substantially immovable longitudinally with respect to the tube, a drill bit arranged at the end of the tube and a rubber held rod interposed between the rod series and the drill bit. l

28. In a rock drill, a composite drill yrod comprising a tube, a series of alined contiguous rods in said tube, means :for holding the rod series under longitudinal pressure and substantially immovable longitudinally with respect to the tube, a drill bit arranged at the end of the tube and an elastically held rod interposed between the rod series and the drill bit and adapted tobe moved longitudinally.

29. In a rock drill, a composite drill rod comprising a tube, a series of alined contiguand drill ous ,rods linsai'd tube, means for lioldin'gthe` rodj series2 under lbngitudiiial pressure and.

substantially immovable longitudinally with' respect to'the' tube, a drill bit arranged at the endl ofthe tubel and ani elasticall'y lield rod interposed between'- the rod-series -and the drill bit and normally liel'djin cont'act with the rod'series l A 5 auf nl a roue dan, a eompo'isaefdiilll'mu' tube andelastic means holding the end rodsV to the tube, said elastic means being under tension so that the rods are held together'in pressure contact. l f l 32. In a rock drill, a composite drill rod comprising a tube, a series of rods in said tube and means" within the tube and engag-` ing the end rods for holding the rods together under pressure.

33. In a rock drill, a composite drill rod comprising a tube, a series of rods held in tight longitudinal contact in said tube and substantially immovable longitudinally with respect to said tube, a rapidly reciprocating hammer arranged to impart the energy of its blowsto said rod series, a drill bit arranged at the end of the tube opposite the hammer. and anelastically held rod interposed between the rod series and the drill bit and adapted to reciprocate.

34.'In a rock drill, a composite drill rod comprising a tube, a series of rods held in tight longitudinal contact in said tube and substantially immovable longitudinally with respect to said tube, a rapidly reciprocating hammer arranged toimpart the energy ot' its blows to said rod series, a drill bit arranged at the end of the tube opposite the hammer and a rubber held rod arranged within the tube between the rod series andy the drill bit. y

35. In a rock drill, the combination with a hammer drilling engine arranged externallyof the drill hole, of a tube extending from the engine intoV the drill hole, means on the l engine for moving the tube longitudinally into and out of the drill hole, a drill bit arranged'on the forward end of said tube and movable longitudinally with respect thereto and a series of elastically held rods insaid tub-e adaptedto transmit the energy of 'the hammer blows to said drill bit.

36. In a rock drill, a drill rod comprising a series of hollow rods pressed together longitudinally in tight'abutting contact, a

hammer drilling engine, a tappet having a passage therein registering with the' passage in the drill rod and means for holdinglthe tappet pressed againstthe end of the Vdrill rod. v

37, In a yrock drill, the combination with a tube, of' a drill bit shank extending into said tube and means elastically holdingthe shank to the tube.

38. In a rock drill, a tube, a drill bit shank extending intel said tube and means interposed between the shank and the tube for elastieally holding the shank to the tube.

89. In a rock drill,fa drill rod adapted to extend into the drill hole, a drilling engine, a rod handling devicemounted on said engine, and an arm on which said engine is 15 mounted for ylongitudinal adjustment, whereby the rod handling device may be moved into alinement with the drill hole.

In testimony whereof, I have hereunto set my hand.

MOSES ARTHUR KNAPP.

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