US2434725A - Electric hammer - Google Patents

Description

Jani 20, 1948. B. w. sNoDGRAss ELEC TRI C HAMMER Filed March l, 1946 3 Sheets-Sheet l l N V EN TOR.

rrams Y V A w Jam 20, 1948l B. WQ sNoDGRAss 2,434,725

ELECTRIC HAMMR Filed March l, 1946 3 Sheets-Sheet 2 l Jan. 20, 1948. B. w. sNoDGRAsS ELEC TR I C HAMMER Filed March l, 1946 3 Sheets-Sheet 3 I N V EN TOR. 5 NJA/WN h( /voeqss Troef/Ey Patented Jan. 20, 1948 Benjamin W. Snodgrass, nver,f(lolo, ssiigiiioi' of one-half to Benjamin F. Englandr'nver,

Colo.

Appiicsfiofi March 1, 194e,seriiiibftsin e claims. (ci. ess-e6) This in`vention relates to powered hammer devices adapted to Agenerate rapidly successive impacts applicable Afor work eiect and t'o direct ysaid impacts to the effective actuation of drills,vchisels, tamps, and analogous tools susceptible of interchangeable association therewith, and more particularlyto electrically-driven such hammer devices, and has as an object to provide an improved constructionanvd cooperative arrangement of elenifentfs constituting 'an improved hammer of high ei'ciency and "wide utility.

AT further `object of the inventionv is to provide an improvedconstrl'iction and'operative mounting for a reciprocatory impact member in an electrically-driven hammer. 1 ,n

A furtherfobject oi the invention is to provide jimproved impactgtrans'mitting tool mounting in 'an electrically-driven hammer.

` AA further object `of the invention is to provide an improved construction and arrangement of rnea'n's automatically operable as an incident of 'ipaot ii'iehlb'er aotton to rotate the tool mounting andgassociated tool of an electricallydriven hammer. A

A `fu-rtherobjeot of the invention is to provide an improved construction and arrangement of means automatically eiective as an incident of hammer "actuation to pressure feed liquid to and 'through thelwork 'end of a t'ol associated 'with an eiec'tncaiiy-driven liiaiiiiiiei.

A further object of the invention is to provide {iniproved operative driving connections between "an impact member reciprooably responsive to rotation 'and a powered shaft in a-Xial alignment with Asaid member. l y I With the foregoing and other objects in view, 'my invention consists in the construction, arrangement, and combination of elements hereinafter s'etrforth, pointed out in my claims, and illustrated by the accompanying drawings, in whch- V g, Figure lisa view, largely in longitudinal, axial section, of a typical embodiment of the invention 'as assembled ready for 'practicall use` Figure 2 an exterior elevation of the assembly according to Figure l takenat arright angle and on a reduced Scale rfr'elativeto said latter figure. Fi`gure 3 is a fragmentary, detail, axial section, on rxan enlarged scale, through tool mounting and 'actuating elements of the assembly according to ajnd substantiallyon the indicated line 3 3 of Figure 1 depicting 4said elements on a plane 15erpendicular to thelshowingwof said latter 'gure and jatfan opposite 'extreme of their range of actuation. Figure 4 is a cross section, von the `'same "of the type s scale as rigie taken jgmrtiiexiniiicatee une lr-44 of Figure 1.A Fijgurefis across section/pri the 'saine scale fais,y Figure 3,., taken Aon thein'dicate'd tiongon the same scale as Figure, taken on the indicated line Sri-6 of Figure 1. Figure 'i kis a cross section, ,on the same scale as Figure 3, taken gouine iiiciiated iiiife 1+i of 4Figure 1. AFigure s A1944, and `are applicable to use with and to enh "ce the pra'cticability and `eilieienoy of electrically-driven ita'ower haiin'ers n 'in Asiil patenti, particularly when suchh rnesar'e employed in the drilling if rieles incident t -infiniiig 'and blasting opera- 'tiorfsr l As Shown rthe daw'igsfa cylindrical casing vitl 'opera'velyiii-nts, houses, and protects the lfilature oidiven shaft "H Vis suitably jurled in 'ai'al coincidence "with said casing. Fixed to and 'for 'rotation vwith one end of the shaft Il, disc-like drive ,iplat I2 is operatively housed 'somewhat iiivvaiaiy from 'one end of the casing ijn @lowly-adjacent, independently-rotatable, hovering relation with thel axially and cylindri- "c'ally recessed end "of a clutch member I3 carried `'iit'e'riorly of said casing end for rotation about an airis 'aligned that 'f the shaft ll`. The recess of the 'irnembe'r l`3covere`d by the plate I2 cojo ratively receives fa pairof complementary, semi-circm i4 having' manica-lagged, rouate outer margins f5 adapted to 'Conform tO and engage at times' against the inner cylindrical wail 'f the ksaid reces-s, and pins it nxediy projec'ting 'a-iial y fron'i the 'outer "face of the plate il. are received tangentially-elongate slots l1 formed in and adjacent the ends of said shoes 'to engage the vlatter'in constantdriven relation fvith said plate y"and shaft Il in a manner permitti g ofv'siepartion and 'iappro'chment of "the shoe elementsaiaiiieiificaiiy bf jsid plate within said u e coil springs T8 of suitable tensile resi e `'oper tively engage between inn margins df trie Sintes r4 and iena to honi said shoes in end abutment the inner limit of their geiilsepar'at out of margin len'gage- Ynt the Inbe'r `i`3 recess inner cylindrical wail; iii which@ @utp saidnshqe's are free to rptft I2 interfi'orly of and Without driving 'eiect on the vrecess and member until such a speed of rotation is attained as will generate centrifugal forces acting on the mass of said shoes suicient to induce outward separation of the shoe elements such as will overcome the tension of the springs I8 and frictionally engage the shoe margins I against the recess wall and in driving relation with the member I3. Wedge blocks I9, having each an outwardly-directed point disposed for Wedging engagement between abutted ends of the shoe I4 elements, are asso- 'ciated with and interiorly of said shoes for limited travel radially of the assembly and for outward shifting in response to speed-generated centrifugal forces, said blocks I9 functioning in an obvious manner to enhance and maintain the frictional grip of the margins I5 against the member I3 recess wall, at proper rotative speeds, and to thereby minimize vagrant fluctuations in the soestablished frictional driving relation. The speed-responsive clutch just described is functionally identical With and structurally very similar to that shown in myearlier patent and in and of itself forms no part of the instant invention, being herein illustrated and described merely to facilitate understanding of the structural and operative relationships of a complete hammer assembly.

The clutch member I3 is formed with a transverse web closing the end of its shoe-containing recess remote from the plate I2 and an annular flange outstanding axially from said web to define a cylindrical cup concentric with the plate I2 and opening outwardly of the casing I9 therefrom; said annular ange projecting axially beyond the adjacent end of the casing I3 for journaled reception within the cylindricallyrecessed end of a tubular casing member 23 xedly end-engaged with and forming an axiallyaligned extension of said casing I0. The casing member 23 is axially traversed by a straight, cylindrical bore opening at one end into the cup defined by the member I3 annular flange and at its other end into a radially-enlarged, concentric, two-diameter, cylindrical chamber whereof the lesser portion is adjacent and communicates through an abrupt angular shoulder 2I with said bore and the greater portion is adjacent and arranged to open outwardly through the casing member 20 end remote from the clutch member I3. A suitably-worked, straight stern 22 is disposed axially of and to extend entirely through the straight bore portion of the casing member 20 in adjustable, interconnecting relation between a double-cone impact head 23 housed within the two-diameter chamber at one end of said bore and a drive disc Ztl housed within the cylindrical cup of the clutch member I3 at the other end of said bore, said stern, impact head, and drive disc constituting a unitary assembly rotatable and reciprocable relative to the casing member 2B. Work-effecting reciprocation of the stem 22, head 23, and disc 2li assembly is developed as a consequence of assembly power rotation through the agency of a double-faced, suitably-contoured cam block 25 adjustably xed to an intermediate portion of the stem 22 within the casing member 2D bore between and f or reaction against independently-rotatable cam followers 26 radially overhanging the block 25 cam margins from their diametrically-oppose'd, axially-spaced, paired mountings in the casing member 20 wall, in much the same manner and with the same effect described in my earlier patent, and power to rotate said assembly is transmitted thereto from the clutch member I3 4 through a plurality of posts 21 fixedly outstanding from the member I3 web in uniformly-spaced angular relation inwardly adjacent and axially paralleling the annular ilange surrounding the drive disc 211, which posts register with and slidably engage through corresponding marginal notches or apertures intersecting said disc 2li, thereby locking said drive disc to and for rotation with the clutch member in a manner to accomvcycle determined by the lobe arrangement and contour of the block cam faces; the illustrated construction being designed to eiect two complete reciprocatory cycles for each revolution of the stem 22 and to free the reciprocatory assembly from every mechanical actuating force or restraint at each limit of its reciprocatory travel, in the manner and for the purposes set forth in my above-identiiied, previous patent.

The end of the casing member 20 remote from the casing I0 xedly engages and cooperates with one end of a tubular sleeve 28 thereby mounted and supported in axial alignment with and as an extension outwardly beyond said casing member end, said sleeve having a straight, axial bore of a diameter somewhat less than that of and communicating at its inner end with the larger portion of the two-diameter chamber housing the impact head 23, so that the sleeve 28 inner end serves to partially obstruct and limit the axial length of said chamber. A tool mounting unit is formed with a straight, tubular end portion 29 of a length slightly greater than that of the sleeve 28 and an external diameter engageable Within the sleeve bore to rotatably and reciprocably mount said portion 29 within and through said sleeve with its inner end projecting into the greater portion of the two-diameter chamber for engagement at times by the impact head 23. An annular, radially-outstanding collar 33 formed integrally about a midportion of the tool mounting unit determines the exterior length of the tubular portion 29 and is t adapted to engage at times against the outer end of the sleeve 28 and thereby limit projection of said portion 29 inwardly beyond the adjacent sleeve end, and a cylindrical extension 3I of said unit axially and outwardly beyond the said collar 3l] is formed with an end-opening, concentric, inwardly-tapered socket 32 separated `from the bore of the tubular portion 29 by a solid transverse web 33 and adapted to telescopically receive, seat, and frictionally grip the correspondingly-tapered end of a tool stock 34. The tool mounting unit is held against separation from and limited in its range of reciprocation outwardlyof the sleeve 2li by an annulus 35 rotatably and reciprocably embracing the extension 3l adjacent the collar 30, said annulus being equipped with fixed, radially-outstanding ears 33 adapted to register with and end-abut against corresponding ears 31 fixedly carried by the sleeve '28 outer end and be clamped thereto by means of bolts 38 engaged through registered holes intersecting said ears in parallelism with the longitudinal axis ofthe tool assembly, adjustment in the spacing between the sleeve 28 outer end land the annulus 35, and hence in the reciprocatory range ofthe tool `mounting unit as determined -by engagemen-t of the collar Swithin such space, being conveniently had -in a usual manner through the use of shims or spacers between adjacent ends of the ears 36 and 31.

As should be manifest from the drawings and Yforegoing description, axial 4reciprocation of the stem `22 deriving from actuation of the shaft Il is reflected adjacent t-he limit of stem Vtravel re- -mote -fromthe casing 'l as impact engagement of the head 23 against the inner end of ^the tool mounting 'unit Atubular portion v2-9, and through `the elements of said tool mounting unit to and ifor -work effect through the stock 34 and tool associated therewith, weight or feed pressure of the -tool assembly applied 4to the stock 34 serving to normally vurge the tool mounting unit to vmaximum inward projection of its tubular portion 29 yfor maintenance of said tubular portion in position for repetitious impact engagement by said head 23. Stem 22 travel Itoward. the casing I ll is arrested by engagement of the impact head inner cone base against the annular shoulder 2l, and the range of stem travel, normal position of the -tool'mounting unit tubular portion inner end, land clearances between cam surfaces of the lblock 25 and the followers '26, are so correlated with other pertinent operative factors and with each other as to synchronously utilize rebound of the head Z3 and associated elements for initiation of travel in a direction adapted for smooth subsequent acceleration by means of the Lpowered associations iprovided.

Certain operations to Awhich the improved hammer is applicable are facilitated and expedited by providing for rotation of the working tool, to -which end means and operative associations effective for such purpose are `incorporated in and with the elements hereinabove described. The tool mounting unit of the improvement being rotatably, as well as reciprocably, carried by the sleeve 28 and annulus 35, and arranged for frictional, rotation-imparting grip with the associated end of the tool stock 34, it is convenient and wholly feasible to apply the powered rotation of the stem 22 and head `23 to eifect tool mounting unit rotation in a practical manner free from disastrous consequences occasioned by sticking tools. As shown, a pair of complementary, semi-cylindrical shoes 39, of suitable rigid material, have their exterior, cylindrical "surfaces suitably friction-lagged, as at 40, and are sized to slip axially within and cooperate to substantially ll the bore in the tubular portion 29 of the tool mounting unit; the lengths of said shoes 39 being slightly less than that of the tubular portion bore, so as to clear said shoe ends from any possible driving engagement with the impact head 23. The plane, diametric faces of the shoes 39 interengageable to complete a shoe cylinder housable within the tubular portion 29 are centrally and longitudinally grooved or routed to form -corresponding transversely-arcuate, relatively wide, shallow channels cooperable when the said shoes .are assembled as shown to denne a transverselyoval bore extending axially of and entirely through the cylinder comprised from the shoes; the so-iormed oval bore being adapted to t snugly about and :slidably accommodate a similarly transversely-oval tongue 4l xedly projecting axially and outwardly from the impact head 23 a distance slightly less than the axial depth of the 6 tubular yportion bore. With the arrangement of elements shown and described, rotation-induced reciprocation-ofthe impact membercarrying the head 23 is reflected without impairment or restriction by a corresponding axial play of the tongue 4l longitudinally vwithin andbetween the shoes 39'; the powered rotation of said impact Vmember operating, -by virtue of -the interengaged tongue and shoe bore cross-sectional outlines, to rotate the shoe assembly and to simultaneously :urge said shoes radially apart and linto 4such frictional `engagement of their 'lagged surfaces :against the tubular portion 29 inner Wall as will rotate the tool mounting and the tool therewith associated. 'While the centrifugal forces of rota- Iencountered by the tool may instantly be accommodated through slippage between the shoe `surfaces 49 and tubular portion 29 without undue strain on, damage to, or interruption in the operation of the hammer assembly elements.

In rock, coal, concrete, and like drilling operations to which the improved hammer is effectively applicable, it is a highly desirable common practice to continuously supply liquid, such as Water,

to the working face of the drill for cooling -eifect on the latter and to free the working area of dust and chips which `impair drilling eiciency, it being usualand convenient to form the tool stock 34 with an axial bore or channel 42 wherethrough such liquid-may Vbe fed to and outwardly from the tool Working end, and a further novelty of the instant invention resides in the provision of means automatically operable .as an incident of hammer actuation to pressure-supply liquid to and through the tool stock. Conveniently adapting the improved hammer for liquid supply to the tool actuated thereby, the driven shaft ll of the hammer motor is extended, through suitable packing glands (not shown), axially and outwardly beyond its'supporting bearing remote from the drive plate `l2 and 'into an end-opening compartment formed in the casing l0 free end, where said shaft engages in driving relation with a gear 43, rotatably housed in said compartment. Radially--offset from and in-meshing relation with the gear 43, a second gear 44 is housed and mounted for rotation about its axis within said casing end compartment, and the inner walls of said compartment are formed and contoured to provide chambers on each side of the diametric plane containing the axes of the gears 43 and 44 and inwardly-extending abutments closely cooperating with the outer opposite arcs of said gears in separating relation between said chambers. A cap 45 removably and replaceably cooperates with the free end of the casing l0 to operatively confine the gears 43 and 44 and to complete the chambers oppositely adjacent thereto, said cap being apertured to provide access to the casing chambers covered thereby and supporting iiow lines 46 and 41 communicating through the cap apertures and with the respective chamber interiors. The meshed gears 43 and 44 constitute a pump operable to draw liquid through one of the flow lines and into the chamber served thereby, to transfer the incoming liquid from the inow chamber to the other chamber of the casing compartment, and to deliver the liquid under pressure as outflow through the other of the flow lines, according to the direction of gear rotation, the line 46 in Figure 1 accommodating liquid inflow and the line 41 functioning as a conduit for pressure outflow when the gear 43 of Figure 6 is rotated in a clockwise direction. The gear pump being productive of operatively adequate suction eifect, the inow line 45 may connect with any convenient source or supply of liquid, such as a sump, tank, reservoir, or the like, and need not be pressure served. The pressure outiiow line 41, which may be either a flexible conduit or a rigid pipe assembly, is led exteriorly of and along the hammer assembly to connection of its delivery end with and radially through the annulus 35, said latter element advantageously being formed with an annular groove 48 shallowly intersecting its inner face and arranged to receive and distribute liquid inflow circumferentially about the adjacent exterior area of the tool mounting extension 3|, and with annular marginal shoulders cooperating with complementary elements on the collar 30 and extension 3l to minimize liquid leakage therebetween. A plurality of flow channels 49 is formed radially of the extension 3| in communicating relation between the inner end of the socket 32 and the outer surface portion of said extension underlying the groove 48, so that the flow delivered to said groove from the line 41 may freely enter the inner socket end and the bore 42 of the tool stock 34 engaged in said socket and be thence pressure-impelled through and outwardly of the tool working face. Thus, actuation of the hammer power unit may be directly and automatically applied to maintain a liquid iiow to and through the tool actuated thereby, whenever and wherever liquid serving of the tool is desired.

The improved hammer assembly may be equipped with manipulating and operating handles and switch in such speciiic construction and arrangement as may be deemed to be practical, such features being conventional in association with hammers of the type disclosed herein, and suitable lugs and brackets for operative engagement with manual or powered feeding mechanisms and supports may be provided in fixed relation with the casing l!) and casing member 2i), as is customary in the application of powered hammers to particular uses.

Since many changes, variations, and modifications in the specific form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claims, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention:

1. In an electric hammer of the character described having a tubular casing assembly, an electric motor housed in one end and with its power shaft axially of said assembly, and a speedresponsive clutch including a shaft-concentric driven member `operatively associated with the motor power shaft inner end interiorly of said assembly, a tool mounting unit rotatably and reciprocably carried in the end of said assembly remote from said motor, an impact member rotatable and reciprocable axially within said assembly between said clutch driven member and tool mounting unit, an axially-slidable, angularly-fixed, rotational driving connection be.. tween said clutch driven member and one end of said impact member, a head on the other end of said impact member for repetitious work-effecting engagement against the tool mounting unit adjacent end, cooperating impact member cam and casing assembly follower means eifective to reciprocate said impact member as an incident of its rotation, a tongue xedly projecting axially from said impact member head in slidably-supported association with said tool mounting unit, and means reactive to rotation of said tongue for frictional engagement with and consequent rotation of said tool mounting unit.

2. Apparatus as Set forth in claim 1, wherein the rotational driving connection between the clutch driven member and the impact member comprises a plurality of studs iixedly projecting toward the adjacent impact member end from, in axial parallelism with, and in angularlyspaced relation on said clutch driven-member, a disc radially of and xed to said impact member adjacent end, and holes in said disc in registraf tion with and to telescopically receive said studs.

3. Apparatus as set forth in claim 1, wherein said tool mounting unit comprises a generally cylindrical body formed with a radially-projecting annular collar intermediate its ends, an axially-bored tubular portion on one side of said collar for journaled reception through the casing assembly end and impact-receiving cooperation with the impact member of the hammer, and a cylindric extension on the other side of said collar formed with an end-opening tool-receiving socket and adapted for journaled cooperation with an annulus xedly supported from and in axial alignment with said casing assembly,

4. Apparatus as set forth in claim 1, wherein the impact member comprises a stem disposable axially of the casing assembly, a disc radially of and threadedly fixed to `one end of said stem for driven association with a rotatable hammer clutch member, a spool-like, double-cone head concentric with and threadedly fixed to the other end of said stem for impact engagement against work-transmitting elements of the hammer, a

" slide tongue projecting iixedly and axially from said head, a tubular cam block on and threadedly fixed to said stem between said disc and head, and cam faces formed on the ends of said block for member-reciprocating cooperation incident to member rotation with followers supported by and in radially-inward projection from said casing assembly.

5. Apparatus as set forth in claim 1, wherein the tool mounting unit rotating means reactive to rotation of the impact member tongue comprises a tool mounting unit tubular portion axially aligned with and opening toward the impact member in telescoping relation over the impact member tongue, a pair of semi-cylindrical shoes nested within and substantially filling the bore of said tubular portion, complementary, transverseiy-arcuate grooves axially of the juxtaposed shoe diametric faces to define an axiallystraight, transversely-oval throat, and a throatconforming, exterior contour on the impact member tongue,

6. In a hammer of the character described having a casing assembly, an impact member power-rotatable within and reciprocable as an incident of its rotation axially of said assembly, and a tool mounting unit journaled in an end of said assemblyk in axial alignment' with said impact member to receive and transmit impacts therefrom, means responsive to impact member rotation for frictionally engaging and yieldably rotating said tool mounting unit, said means com.. prising a tubular unit end portion aligned with and opposed to said impact member, a pair of semi-cylindrica1 shoes nested within and substantially filling the bore of said tubular portion, friction lagging on the shoe cylindrical surfaces, complementary, transversely-arcuate grooves axially of the juxtaposed shoe diametric surfaces to define an axially-straight, transversely-oval throat, and an axially-straight, transversely-oval tongue projecting xedly and axially from the adjacent impact member end for slidable, nonrotatable engagement within said throat.

BENJAMIN W. SNODGRASS.

REFERENCES CITED The following references are of record in the le of this patent:

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