US2794621A

US2794621A - Drilling attachments

Info

Publication number: US2794621A
Application number: US230941A
Authority: US
Inventors: Martin L Beeson
Original assignee: Individual
Current assignee: Individual
Priority date: 1951-06-11
Filing date: 1951-06-11
Publication date: 1957-06-04
Anticipated expiration: 1974-06-04

Description

M. L. BEESON DRILLING ATTACHMENTS June 4, 1957 3 shets-sheet 1 vFiled June 11, 1.9 51

25 mvENToR MARTIN L. BEESON JjgxJ. I

June 4, 1957 M. L. BEEsoN DRILLING ATTACHMENTS 3 SheejtshSheet 2 Filed June 1;, 1951 June 4, 1957 M. L. BEEsoN DRILLING ATTACHMENTS Filed June 11, 1951 3 Sheets-Sheet 3 NVENTOR MARTIN I .BEESON ATTGRN EY nited States Patent O DmLLING ArrACmuENrs Martin L. Beeson, South Pasadena, Calif., assigner of one-half to William D. Sellers, Pasadena, Calif.

Application June 11, 1951, Serial No. 230,941

20 Claims. (Cl. 25E-41) The present invention relates to drills in general and particularly to an apparatus by which the rotary power of the drill is converted into a rotary reciprocatory movement of the tool bit. More specifically the invention comprises an attachment adapted to be connected between the driving unit and the working drill bit to transform the rotary motion of the unit shaft into a rotary and longitudinally reciprocating motion at the bit.

Rotary drills are used today in working in metals and other materials which, while less hard, are very abrasive. They find great usefulness particularly in the drilling of holes in concrete and cement. Pneumatic hammers have long been used for that purpose but are objectionable in that they are a special purpose tool of relatively great cost. Star drills are also usable but are primitive, slow, `and involve considerable physical effort on the part of the worker. Until recent years rotary drills were not extensively used in `the drilling of concrete and cement but with the production upon large scale of tungsten carbide and other sintered products of great hardness it became possible to incorporate such materials in the drill bit as cutting elements to effect a material increase in the drill life. Thereupon rotary drills became popular but there remained the objection that a relatively great pressure upon the drill was required. In order to force the drill into the material at times one worker would hold the drill, pushing against it, While a second worker pushed the rst. In other applications use would be made of a lever arm by which greater force could be brought to bear upon the drill.

In the apparatus constructed in accordance with the present invention the shortcomings and defects of theprior art constructions have been eliminated while use has been made of their advantages. The present invention incorprates a rotary drill bit with its cutting edge or edges, as in the prior art devices, and makes use ot a rotary driving unit which, in a preferred form, is electric. In addition it incorporates means by which the cutting drill bit is reciprocated longitudinally under a hammer action to eiect :a chipping of the material in the hole so that the rotation of the drill eiects not only a cutting abrasive action but in addition a chipping action. The result is faster drilling and the elimination of the requirement of excessive force upon the drill.

lt has also been found that in working in various materials the force of the hammer blows can be varied advantageously. In extremely hard material the harder the blow the greater the cutting speed. In certain brittle materials, as for example marble, a very hard blow may crack the body being drilled and so it becomes desirable to reduce the force when working in that material.

It is an object of the present invention to provide a new and improved drilling apparatus in which a rotary drill is rotated and reciprocated longitudinally.

it is another object of the invention .to provide a drilling apparatus in which a rotary fdrill bit is hammered into the material by the drill during the drilling operation.

2,794,621 vrPatented June 4, 1957 A still further object of the invention is to provide lan improved drilling apparatus in which the power of the rotary driving unit is translated into rotary power and reciprocating power at the cutting drill.

A further object of the invention is to provide an irnproved attachment adapted to be connected between the usual electric driving unit, commonly known as a rotary drill, and the cutting drill bit, which is also known as a drill, for the purpose of transforming the rotary driving power of the driving unit shaft into rotary and reciprocating motion at the cutting tool.

A further object of the invention is to provide a drilling apparatus of light weight adapted tov be carried by the operator which converts the rotational force of an electric driving motor into a rotary reciprocatory motion at the cutting bit and which includes a manual adjustment by which the impact force can be varied selectively.

These and other more specic objects will appear upon reading the following speciiication and claims and upon considering in connection therewith the attached drawings to which they relate.

Referring now to the drawings in which preferred embodiments of the invention are'illustrated:

Figure 1 is a side View of an ordinary electric drill unit connected to a drill bit by an attachment constructed in accordance with the present invention;

Figure 2 is :an enlarged longitudinal section through the attachment shown in Figure l;

Figure 3 is a transverse section looking in the direction of the arrows upon the line 3.,-3, of Figure 2,;

Figure 4 is a transverse section upon the line 47-4 of Figure 2 and discloses the cam means by which rotational movement of the rotary drill shaft is converted into reciprocatory movement of the drill bit unit;

Figure 5 is a transverse section upon hte line 5 -5 of Figure 2 and shows the sliding connection between the cam :and the shaft which enables the cam to be adjusted longitudinally 01.1 the Shaft;

Figure 6 s a transverse section upon the line 6 6V of Figure 2 and illustrates the slidable connection between the two parts of the attachment shaft and also 4the con centric relationship of the reciprocatory hammer; A

Figure 7 is an enlarged longitudinal section through a second preferred embodiment of the invention. Y Y

Figure 8 is a view of the end of -the attachment looking in the :direction of the arrows upon the line 8-8 of Figure 7;

Figure 9 is a transverse section upon the line 9-,9 of Figure 7; I

Figure 10 is a transverse section upon the line 10-10 of Figure 7; Y

Figure ll is a partial longitudinal section of the am follower adjustment assembly upon the line 11-11 of Figure 7;

Figure 12 is a detail view of the key used to lock the cam follower adjustment -assembly in place in the hammer;

Figure 13 is a View of the cam follower and guide;

YFigure 14 is an enlarged longitudinally section through a third embodiment of the invention; v l,

Figure l5 is a transverse section upon the line 15.-15 of Figure 14 through the manual adjustment by which the impact force is controlled;

Figure V16 isa transverse section upon 'line 16%16 of Figure 14 and shows the face of the cam and the plurality of ca-rn followers riding thereon;

Figure 1-7 is a transverse section on line 17-17 of Figure 14 and shows the connection between the cam and the Vshaft and the concentric relation of the hammer with respect to both; and

Figure 18 is a transverse section on line 18-,18 of Figure 14 and illustrates the means by which the two ice shafts of the attachment are connected for conjoint rotary movement and relative longitudinal translation.

Referringnow to the rst embodiment of the invention shown in Figures l to 6, inclusive, of the drawings, and to Figure l in particular, an electric drill comprising a power unit is generally indicated by .the reference character 2@ and comprises an unshown driving motor, a casing 21 housing said motor, the motor shaft carrying a chuck 22. A handle 23 extends from the upper end of casing 21 and through it pass the leads Y24 which conduct current to the electric motor upon applying finger pressure to lever 26 which closes an unshown switch completing the electric circuit between the power source and the electric motor.' The cutting drill orbit is indicated generally by reference character 25 and 1n the usual prior art devices would be connected directly to the chuck 22 of power unit 20. According to` the present invention, however, the attachment unit., 1ndi cated generally by reference character 30, is positioned between the chuck and the cutting tool as shown Vin Figure l.

, Referring to Figure 2, the unit 30 is seen to include a cup-shaped casing 31, forming the bottom and side walls of a chamber, and an upper end wall 32 fixeclly attached to casing 31 by screws 33. A centrally bored shaft 36 1s rotatably journalled in a bearing 37 positioned in upper end wall 32 and carries a transverse pin 38 near its lower end in casing 31. A second and aligned shaft 39, threaded at its lower end at 64 below the casing, is centrally bored at its upper end at 40 and slidingly encloses the end .of shaft 36. Shaft 39 is formed at its inner end with diametrically apposed notch seats 41 slidingly seating the pin 38 carried by shaft 36. Shaft 39 is itself rotatably and slidingly carried by a sleeve bearing 42 positioned 1n the end face of casing 31. Just inside bearing 42 shaft 39 is formed with a circumferential shoulder or enlargement 43 which serves as an anvil, as will be described.

A hammer 44 slides upon the upper end of shaft 39 within casing 31 and is at all times resiliently urged. in the direction of the anvil 43 by an encircling coil spring 46, one end of which abuts the hammer at a circumferential seat-forming shoulder 47. The other end of spring 46 seats in a retainer ring 48 slidingly positioned in the cylindrical wall of the casing 31 and movable toward and from the end wall 32. Rotation of the hammer 44 in casing 31 is prevented by radial keys 56 fixed to the casing side wall and extended into longtiudinal grooves 51 in the sides of the hammer.

A cam 54 encircles and is adjustably secured to shaft 36 being located within a central bore 58 in hammer 44. As illustrated more clearly in the embodiment shown in Figure 7, the upper face of cam 54 is contoured to provide two gradual lifts each having an abrupt cutoff. Two -diametrically spaced cam followers 56 are affixed on the inside wall of the cylindrical bore 58 of the hammer and ride upon the cam 54 under the force exerted by coil spring 46. The lift of the cams is such that upon the followers 56 reaching the cnt-offs the spring 46 snaps the hammer toward and into contact with the anvil 43. To prevent the latter from striking the end of bearing 42 the inner end of the bearing is positioned just below the surface of the casing end wall. Additionally a raised circular shoulder 45 is constructed on the inside face of the end wall of the casing encircling the anvil 43. The height of the shoulder 45 above the casing end wall is suticient that with the anvil 43 abutting the inside face of the casing end wall, as it will when no rneans are supporting bit 25, the annular shoulder will receive the shock of the downward snap of the hammer.

The central bore in the shaft 36 co-incident with its axis is identied by the reference character 34 and an elongated cylindrical pin 53 is positioned slidingly therein, a .transverse pin 49 secured near its end extending laterally in both directions through diametrically spaced elongated slots 52 in shaft 36 to support the cam 54. Pin

53 carries a second transverse pin 60 at a point above the end wall 32 of casing 31 which extends laterally through elongated slots 65 in shaft 36 which is exteriorly threaded at that point. A knurled nut 59 is threaded on shaft 36 above the casing end wall 32 below and in supporting position to the ends of pin 60. A coil spring in bore 34 urges pin 53 downwardly and transverse pin 60 against the upper surface of nut 59. Compression is applied to spring 55 by a cap 67 threaded interiorly into bore 34 and abutting spring 55 at its upper end. Y

By selectively threading the nut 59 upwardly or downwardly on shaft 36 cylindrical pin 49 with attached cam 54 may be raised or lowered in casing 31 and is adjusted relative to the hammer 44 and the cam followers 56 which it carries. The purpose of the adjustment is to vary the length of longitudinal displacement, that is, the lift of the hammer 44 occurring upon rotation of shaft 36. Clearly the higher the cam 54 is raised in casing 31 the greater will be the lift given the hammer 44. With cam 54 in its uppermost position, determined by the transverse pin 60 striking the upper end of slot 65, the cam followery 56 will, in riding on the cam, be raised to its uppermost position. The length of stroke is substantially equal to the distance between the bottom face of the hammer and the upper face of the annular shoulder 45.

To vary the force with which hammer 44 strikes anvil 43 means are provided to adjust the spring 46 by shifting the position of retainer 4S in casing 31. Pins 48a on the retainer 48 extend upwardly through holes in casing end wall 32. The outer ends of the pins abut aV rotatable collar 61 threaded on the exterior of a flange 63 extending outwardly from plate 32. By threading the adjustment collar inwardly or outwardly the pins, and so the attached retainer 4S, are moved along the casing side wall and the spring 46 is compressed or decompressed.

The lower end of shaft 39 carrier a chuck 66 rotatable therewith and adapted to receive and seat the shank of drill bit 25 formed with a suitable cutting tip at its opposite end adapted to work in concrete and cement. Chuck 66 may be of a type adapted to open and close upon being turned relative to its supporting shaft or, if preferred, may be key operated, it being requisite only that it retain its adjustment in the presence of continued and relatively violent vibration.

It is essential that the attachment casing 31 be fixed with respect to the casing of power unit 20 in order that it not rotate with the motor shaft. To accomplish this result casing 31 is provided with a rigidly connected bracket comprising an elongated spring arm 71 carrying a't its outer end a serrated U-shaped seat 72 adapted partially to enclose the lower end of the motor casing. lf preferred, or if the bracket 71 does not properly engage the motor housing 21, the attachment can be held against rotation by means of a handle 73 extended laterally from the cup-shaped body casing 31.

Referring now to the embodiment of the invention shown in Figures 7 to 13, inclusive, the details of construction are the same as those in the first embodiment except that the adjustable spring retainer means to vary the spring tension in the coil spring 46 is eliminated and a different construction is used to vary the length of the hammer stroke. In this construction a bore 81 is drilled in the hammer 44 from the top face thereof r and slidingly seats the guide post 32 of cam follower 84. A coil spring 83 in bore $1 urges the follower upwardly. The cam follower 84 extends laterally into and is slidable in two vertical slots 85 in the hammer upon opposite sides of the bore 81. The bore 81 is partially counterbored from the upper surface of the hammer and is threaded at 86 to seat the lower enlarged and exteriorly threaded end 87 of an elongated stem 91. Enlarged endV S7 of the stem 91 .abuts the upper surface of cam follower 84 to determine its upper position relative to hammer 44 and under the urging of spring 83. A key 89, shown in detailed perspective in Figure 12. seats in a slot 90 in the top face of the hammer at the mouth of bore 81, as shown best in Figure l1. The key is slotted in order that the stem 91 may be adjusted longitudinally therethrough. The presence of the key prevents the threaded end 87 of the stern from being backed out of its threaded seat in the hammer bore 81. From its seat in the hammer 44 the stem 91 extends upwardly through a bore 92 in the upper end wall 32, as shown in Figure 8, and at it-s end carries knurled knob 93 by which it may be rotated to adjust it in its threaded seat in the hammer.

. In this alternate embodiment as contrasted with the first described embodiment it is noted that the cam 54 is rigidly attached by a pin 54a to a solid shaft 36a and is not adjustable longitudinally relative thereto. By turning the knurled knob 93 the position of the stem 91 is adjusted in the hammer 44 and relative to the cam 54. The purpose of this adjustment is to vary the length of hammer stroke and the force of the blow delivered. As the follower 84 moves with the hammer, although adjustable relative thereto as described, it is clear that its position relative to the hammer and to the longitudinally fixed cam 54 will determine hammer displacement. With the follower adjusted to its lowermost adjusted position in the hammer the hammer stroke will be the greatest, for the follower will travel the maximum longitudinal distance in riding over the cam 54. Similarly with the follower in its highest adjusted position in the hammer the stroke will be the smallest, for the follower will be displaced the least in riding over the cam.

A third preferred lembodiment of the invention is shown in Figures 14 to 18, inclusive, which is generally similar to the rst embodiment except as specied A stem 102 fits slidingly in the bore 95 of upper shaft 36 and 'carries a radial pin 101 extended from it-s upper end outwardly through a slot 110 in the shaft 36, through corresponding slots in an encircling inner sleeve 100, and terminating in helical grooves 99 in an outer or cam sleeve 98. A knurled rotatable control collar 97 ts around cam sleeve 98 and is secured thereto as by a set screw. An annular ring 94 with a knurled outer surface is secured xedly to shaft 36 and by holding that ring firmly with one hand the rotation of shaft 36 may vbe prevented while the other hand turns the collar 97 and the cam sleeve 98. Upon the rotation of outer sleeve 98 the pin 101 riding in the grooves 99 is shifted longitudinally, downwardly or upwardly, on shaft 36, depending on the direction of rotation.

A plate 96 is threaded on shaft 36 and rmly abuts the upper end of inner sleeve 100 forcing it downwardly against a locking ring 117 `securing the bearing 37 in its seat in casing end wall 32. The inner sleeve 1'00 is thus secured relative to the shaft. There is slight 'clearance between the upper ends of the collar 97 and cam sleeve 98 and the plate 96 so that the collar and cam can be rotated manually with respect to the shaft and plate.

At the `lower end of stem 102 .a fixed pin 107 extends laterally on both sides through elongated slots 106 in the wall of the hollow shaft 36 and into a -cam 54. Cam 54 encircles shaft 36 and is longitudinally adjustable thereon as the collar 97 is rotated to adjust the stern 102 inside sthe shaft. Radially extending cam followers 108 are secured to hammer 44 by set screws 109 and ride on cam 54. With the cam '54 in its highest position von shaft 36 hammer 44 will be raised to its highest vertical position as the lfollowers 108 ride thereover and the working stroke of the hammer is a maximum. As the cam is adjusted downwardly the length of the stroke is reduced. In a manner similar to the construction of the rst embodiment a coil spring, here indicated by the reference character 103, is provided acting on the upper end of the stem. Here, however, the spring 'backs 6 against a stop plug 104 and its sole purpose is to prevent looseness and rattling of the stem.

In this embodiment of the invention cam 54 is provided with three gradual lifts and three abrupt cut-offs spaced 120 degrees apart. The same number of followers are used. As in 'the preceding embodiment the lower end of inner shaft 36 iits slidingly in the bored upper end of the outer shaft 39. Relative rotation between the two shafts is prevented by keys 114.

In this embodiment the striking power of the hammer 44 is provided by three coil springs acting in tension as distinguished from the previous embodiments in which the power of a single spring acting in compression was used. The tension springs are positioned in longitudinal grooves or channels circumferentially spaced at equal intervals around cylindrical hammer 44. The upper end of each spring 105 engages a suitable pin 111 fixed to the hammer while its lower end is secured to a iiange 112 integral in the casing 31.

As in the other embodiments of the invention rotation of the attachment with respect to the casing of the power unit 20 is prevented by a bracket comprising a spring arm 71 extending upwardly and carrying at its end a serrated U-shaped seat 72 adapted to enclose the lower end of casing 21.

In the operation of the rst embodiment of the present invention the closing of the control switch 26 results in the ow of current through leads 24 to the electric motor of the power unit 20, whereupon the motor shaft rotates and with it chuck 22 positioned at its lower end. This rotation is transmitted .to connected shaft 36 of unit 30 which rotates in its bearing 37, the casing being prevented from rotation by the bracket 71. Shaft 36 carries the cam 54 and the rotation of the latter eiects longitudinal displacement of the followers 56 and of the hammer 44 xedly connected thereto. The displacement of the hammer under the action of the cam 54 -compresses the spring 46 whereupon the latter effects the return of the hammer 44 with a snap action as followers 56 ride over the cut-offs of the cam. In the second embodiment the same action takes place as the follower 84 rides over its cam 54. In the third preferred embodiment of the invention each displacement under the action of the cam tensions the three springs 105, whereupon the latter effect the return of the hammer with a snap action as the followers 108 ride over the cam cut-offs. In each instance the hammer 44 strikes the anvil 43 a sharp blow resulting in the longitudinal displacement of shaft 39 relative to the driving shaft 36. It is seen that no longitudinal force is 'transmitted by this blow back through the shaft 36 to the driving motor because of the presence of the pin and

slot connection

33 and 41 in lthe first and second embodiments, and because of the presence of the key and

groove connection

114 and 116 in the third embodiment.

The blow transmitted to the shaft 39 is directly effective through chuck 66 on the drill bit 2S to drive the lower cutting end thereof into the material. It is sometimes desirable to vary the force lof the blow struck and this can be done in the .rst preferred embodiment of Figure 2 by :the manual adjustment of collar .61 upon the threaded ange 63 on upper end plate 32. The rotation -of collar 61 in one direction provides greater compression in spring 46 upon lrotation Yof cam 54 and 4results in the striking of a harder blow by hammer v44, while the rotation of collar 61 in 'the reverse direction l,produces the opposite result.

lt is sometimes desirable -to vary the 4length vof `the reciprocatory stroke of the drill -bit 25. This ,may be done by varying the maximum lift of the hammer in the casing. In the first embodiment this is accomplished Vby rotating knurled collar 59 :on shaft 36. its Irotation in one direction moves the cam vertically upward on the shaft 36 to increase the lift of the hammer and so the stroke of the bit which follows the hammer, whereas rotation'of collar 59 in the opposite direction has the opposite effect. In the secondembodiment, Figure 7, the stroke of the bit is increased by rotating knob 93 in one direction to lower cam follower 84 in the hammer 44, whereas by rotating the knob in the opposite direction the follower is raised in the hammer and the stroke of the bit is. decreased.l In the third embodiment, Figure 14, rotation of knurled collar 97 in one direction moves the cam 54 vertically upward on the shaft to increase the lift of the hammer andthe stroke'of the bit, whereas its rotation in the reverse direction has the opposite effeet. In increasing the lift of the hammer in the casing by the adjustments aforesaid a blow ofV greater force, as welly as increased stroke of the drilling bit Z', is` achieved.

With the drilllifted from contact with a surface being worked upon the force of the blow normally delivered to anvil 43 on shaft 39 is transmitted to the inner end face of the annular ring 45 constructed in the bottom of body casing 31. VThe latter is so dimensioned that the downward travel of the hammer is stopped in time to prevent the follower 56 which moves with it from transmitting a blow to cam S4 connected to shaft 36 which would be transmitted directly to the driving motor, an undesirable result.

From the foregoing it is clear that the drill and attachment constructed in accordance with the present inventionV operate with the advantages characterizing the rotary drills of the prior artand in addition thereto insure a more effective drilling operation through providing a reciprocating impact action characteristic of the pneumatic hammers.

While the particular apparatus herein shown and described in detail is fully capable of attaining the objects,

and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as Vdefined in the appended claims.

I claim:

l. In a drill construction, a driving shaft, an aligned driven shaft, means carried by said driven shaft to seat a working tool, an anvil on said driven shaft, means connecting said driving and driven shafts for conjoint rotary and relative longitudinal motion, a cam on said driving shaft, a hammer exterior of said driving and driven shafts and movable relative to said cam to strike said anvil, means including a cam follower connected to said hammer and associated with said cam to effect reciprocation of said hammer to deliver a striking blow to said anvil, and manually adjustable means to adjust said cam relative to said driving shaft to vary the stroke of said reciprocating hammer.

2In a drill construction, a casing, a driving shaft journaled in said casing, an aligned driven shaft journaled in said casing, means carried by said driven shaft to seat a working tool, an anvil on said driven shaft, a cam aiiixed slidingly on said driving shaft for rotation therewith and for longitudinal movement relative thereto, means connecting said driving and driven shafts for conjoint` rotary and relative longitudinal motion, a hammer exterior of said driving and driven shafts and movable relative to said cam to strike said anvil, a cam follower carried by said hammer, a spring retainer adjustably mounted in said casing, a coil spring clamped between said retainer and said hammer in compressed relationship and adapted toi biassaid hammer toward said anvil, said cam rotating against said cam follower to effect movement of said hammer against the pressure of said compression spring and in a direction away from said anvil, means manually to adjust said cam on said driving shaft to vary the stroke of said hammer, andan adjustment for said spring retainer to vary vthe residual compression of said spring and thus the strength of the hammer blow inganni etected by said spring upon release of said cam follower by said cam.

3. In a drill construction, a casing, a driving shaft extended into said casing, a cam axed slidingly on said driving shaft for rotation therewith and for longitudinal movement relative thereto within said casing, a driven shaft aligned with said driving shaft and having'an anvil thereon within said casing, said driven shaft projecting from said casing and being adapted to seat a working tool, means connecting said driving and driven shafts for conjoint rotation and independent longitudinal displace.- ment, a hammer movable in said casing to strike said anvil to deliver a blow through said driven shaft to said working tool, a cam follower on said hammer and op erably associated with said cam, a spring retainer in said casing, a coil spring positioned between saidhammer and said retainer to effect movement of said hammer in one direction after movement thereof in the other direction due to operation of said cam and cam follower, and an adjustment to change the position of said cam on said driving shaft and thus vary the stroke of said hammer.

4. In an attachment for drills, a casing, a drive shaft projecting from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts for conjoint rotation and indepedent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts, a cam affixed slidingly on said drive shaft for rotation therewith `and for longitudinal movement relative thereto, a follower mounted for relative reciprocation upon rotation of said drive shaft and cam, a longitudinally displaceable hammer connected to said follower, an anvil carried by said driven shaft, spring means acting upon said hammer to force it against said anvil, and an adjustment to alter the position of said cam on said drive shaft to vary the Vamplitude of displacement of said hammer.

5. In an attachment for rotary power tools, a casing, a drive shaft projecting from said casing and adapted to be connected to the rotating shaft of a power tool, a driven shaft adapted to be connected to a tool, said driven shaft being aligned with said drive shaft, a connection between said drive and driven shafts in said casing, a cam and cam follower mounted for rotation relative to each other `and for reciprocation of said follower during rotation of said drive shaft, a longitudinally displaceable non-rotating hammer slidably mounted in said casing for movement parallel to the axis of said shafts, said hammer being connectedto said follower for displacement thereby in one direction, said cam being mounted on said drive shaft for longitudinal movement relative thereto, means to adjust said cam in a marmer varying the longitudinal displacement of said follower and said hammer, `an anvil carried by said driven shaft and positioned to be contacted by said hammer, and a spring acting upon said hammer to force it toward said anvil and opposing its displacement by said cam and follower.

6. In an attachment for drills, a casing, a drive shaft projecting from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft Vadapted to -be connected to a drill bit, means connecting saiddrive and driven shafts in said casing, cam and follower means mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable nonrotating hammer slidably mounted in said casing for movement parallel to the axis of said drive shaft, said hammer being connected to said cam and follower means for displacement thereby in a direction away from said drill bit, an anvil carried by said driven shaft and disposed between said hammer and drill bit, said hammer being formed with a seat on its endremote from said drill bit, a retaining ring facing said hammer seat and adjustably mounted in said casing, a compression coil spring retained in clamping relationship between said hammer seat and said retaining ring, and means manually to adjust the position of said retaining ring in said casing to vary the residual compression of said coil spring and thus the force exerted thereby opposing the displacement -of the hammer by said cam and follower means.

7. In a drill construction, a driving shaft, an aligned driven shaft, means carried by said driven shaft to seat a working tool, an anvil on said driven shaft, -means yconnecting said driving and driven shafts for conjoint rotary and relative longitudinal motion, a cam on said driving shaft, a hammer exterior of said driving yand driven shafts and movable relative to said cam to strike said anvil, a cam follower connected to said hammer for movement relative thereto and parallel to the axis thereof, said cam and cam follower effecting reciprocation of said hammer to deliver a striking blow to said anvil, and an adjustment to vary the position of said cam follower on said hammer and thus change the stroke of said hammer.

48. In a drill construction, a casing, a driving shaft extending into said casing, a cam carried by said driving shaft within said casing, a driven shaft aligned with said driving shaft, an anvil on said driven shaft in said casing, a chuck carried by said driven shaft exteriorly of said casing and adapted to seat a working drill, means connecting said driving and driven shafts -for conjoint rotation and independent longitudinal displacement, a hammer exterior of said driving and driven shafts and movable .in said casing to strike said anvil and thus deliver a blow through said driven shaft to said working drill, a compression spring, a cam follower connected to said hammer for adjustment thereon and parallel to the axis thereof, said cam follower and said spring being adapted to reciprocate said hammer upon rotation of said driving shaft and said cam, and an adjustment to shift the position of said cam follower on said hammer to vary its maximum displacement.

9. ln an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill bit, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, a cam mounted for rotation by said drive shaft, a longitudinally displaceable hammer positioned radially outside said driven shaft, a cam follower connected to said hammer for relative movement thereon parallel to its axis, a coil spring seated on said hammer .in said casing, said cam follower riding on said cam to displace said hammer and to compress said spring, an anvil carried by said driven shaft, said spring acting upon said hammer to force it against said anvil upon release of said follower by said cam, and an .adjustment to vary the position of said cam follower on said hammer 'and thus change the stroke thereof.

l0. In an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill bit, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting said drive and driven shafts in said casing, cam and follower means mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable, non-rotating hammer slidably mounted in said casing for movement parallel to the axis of said drive shaft, said hammer being connected toV said cam and follower means for displacement thereby in one direction, said cam follower means being mounted on the hammer for relative movement thereon and parallel to the axis thereof, an anvil carried by said driven shaft and positioned to be contacted by said hammer, a spring acting upon said hammer and opposing its displacement by said cam and follower means, said spring exertingra force to rI() drive said hammer against said anvil upon release of said hammer by said cam and follower means, and meansto adjust the position of said cam follower means on said hammer to vary the longitudinal displacement thereof.

ll. In an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, cam and follower means including a cam and a follower mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable hammer positioned radially outside said driven shaft and connected to said earn and follower means for displacement thereby, a stem mounted for sliding movement within a bore in said drive shaft, an elongated slot pro'- vided in said drive shaft through said bore, a transverse pin extending through said slot and atiixing said cam to said stern, means to adjust said stern .in said bore within the limit of said slot and thus vary the position of said cam and the stroke of said hammer, an anvil carried by said driven shaft at one end of said hammer, and a spring acting on said hammer to force it against `said anvil upon release of said hammer by said cam and follower means. j

12. In an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill lbit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting said drive and driven shafts in said casi-ng, cam and follower means including a cam vand a follower mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable nonrotating hammer mounted in said casing for movement parallel to the axis of said shafts, said hammer being associated with said cam and follower means for displacement in one direction, a stem mounted within an axial bore in said drive shaft for sliding movement relative thereto, an elongated slot formed in said -drive shaft through the bore, a transverse pin amxing said cam to said stem and extending through said elongated slot, means to adjust said stem in said bore to shift the position of the cam on the drive shaft and thus vary the amount of displacement of said hammer, an anvil carried by said driven shaft `and positioned to be contacted by said hammer, and a spring exerting a force to drive said hammer against Vsaid anvil upon its release -by said cam and follower means.

13. In a drill construction, a driving shaft, an aligned driven shaft, means carried by said driven shaft to seat fa working tool, means connecting said driving and driven shafts for conjoint rotation and independent longitudinal displacement, a cam movably mounted on said driving shaft, said driving shaft being provided with an axiai bore, .a stem slidable in said bore, an elongated slot provided in said driving shaft through said bore, a transverse pin extended slidably through said slot and aiiixing said cam to said stem, means to move said stem within said bore to any desired position within the limit of said slot to adjust the position of the cam on the driving shaft, a longitudinally reciprocating hammer movable relative to said cam, an anvil positioned on said driven shaft, and means including 'a cam follower connected to said hammer to effect reciprocation of said hammer to deliver a striking blow to said anvil. t

14. In an lattachment for drills, a casing, a bracket extending from said casing and adapted to seat upon the adjacent end of a drill to prevent relative rotation be- :Maasai tween said casing and drill, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of said drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with said drive shaft, means connecting said drive and drien shafts in said casing for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, cam means, means to adjustably mount said cam means on said drive shaft for rotation therewith, a longitudinally displaceable hammer positioned radially outside said driven shaft and having follower means thereon associated with said cam means, said'hammer being nonrotatably mounted and being longitudinally displaced due to operation on said follower means by said cam means, the longitudinal adjustment of said cam means on said drive shaft adjusting the stroke of said hammer, an anvil carried by said driven shaft at one end of said hammer, and a spring acting upon said hammer to force it against said anvil upon release of said hammer by said cam and follower means.

l5. In an attachment for drills, a casing, a bracket extending from said casing andY adapted to seat upon the adjacent end of a drill to prevent relative rotation between said Vcasing and drill, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of said drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts in said casing for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, cam means and follower means operably associated with each other, a stem slidable in an axial bore in said drive shaft, an elongated slot in said drive shaft intersecting said axial bore, a transverse pin slidable in said slot and aixing said cam means to said stem, means to move said stem within the said bore to any desired position to adjust the position of the cam means on the drive shaft, a longitudinally reciprocating hammer positioned radially outside said driven shaft and connected to said follower means for displacement due to operation on said follower means by said cam means, the stroke of said hammer being varied by adjusting said cam means on said drive shaft, an anvil carried by said driven shaft at one end of said hammer, and a spring acting upon said hammer to force it against said anvil upon the release of said hammer by said cam and follower means.

16. In an attachment for drills, a casing, a bracket extending from said casing and adapted to seat upon the adjacent end of a drill to prevent relative rotation between said casing and drill, a drive-shaft extended from said casing and adapted to be connected to the rotating shaft of said drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts in said casing for conjoint rotation and independent longitudinal displacement, bearings rotatably' supporting each of said drive and driven shafts in said casing, cam and follower means mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable hammer positioned radially outside said driven shaft and connected to said cam and follower means for displacement thereby, an anvil carried by said driven shaft at one end of said hammer, a seat formed on said hammer, a spring retainer adjustably positioned in said casing, a compression coil spring retained in said casing between said hammer seat and said retainer, and means to adjust the position of said retainer in said casing to vary the residual compression of saidV spring ,and the maximum force with which said spring acts upon said hammer to force it against said anvil.

l7. In an attachment for drills, acasing, a bracket extending from said casing and adapted to seat upon the adjacent end of a drill to prevent relative rotation between said casing and drill, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of said drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts in said casing for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, cam and follower means mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable hammerpositioned radially outside said driven shaft and connected to said cam and follower means for displacement thereby, said cam follower means being connected toi the hammer and adjustable'relative thereto parallel to the axis thereof, a manually4 operated adjustment to vary the position of said follower means on said hammer, an anvil carried by said driven shaft at one end of said hammer, and a spring acting upon said hammer to force it against said anvil upon release of said hammer by said cam and follower means.

18. In an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting said drive shaft, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, cam and follower means mounted for rotation relative to each other rotation of said drive shaft, a longitudinally displaceable hammer positioned radially outside saiddriven shaft, said hammer serving as a mounting for said cam and follower means so as to be longitudinally displaced due to rotation of said cam and follower means relative to each other, an anvil carried by said driven shaft at one end of said hammer, and a plurality of springs positioned in grooves spaced around the walls of the hammer, each of said springs being secured to the bottom of said casing and to said hammer, said springs acting upon said hammer to force it against said anvil upon its release by said cam and follower means.

19. In an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill,y a driven shaft adapted to be connected to a drill bit, said driven shaft being aligned with and abutting saidV drive shaft, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings rotatably supporting each of said drive and driven shafts in said casing, cam and follower means mounted for rotation relative to each other upon rotation of said drive shaft, a longitudinally displaceable non-rotating hammer Vmounted in said casing for movement parallel to the axis of said shafts, said hammer serving as a mounting for said cam and follower means so as to be longitudinally displaced due to rotation of said cam and follower means relative to each other, an anvil carried by said driven shaft and positioned to be contacted by said hammer, and a plurality of tension springs positioned in grooves spaced equidistantly around the wall of said hammer, said springs connecting said hammer with said casing and exerting force on said hammer to oppose its displacement by said cam and follower means, said tension springs serving to displace said hammer into contact with said anvil when said hammer is released by said cam and follower means.

20. In an attachment for drills, a casing, a drive shaft extended from said casing and adapted to be connected to the rotating shaft of a drill, a driven shaft adapted to be connected to a drill bit, means connecting said drive and driven shafts for conjoint rotation and independent longitudinal displacement, bearings supporting said drive and driven shafts in said casing, a cam mounted for rotation upon rotation of said drive shaft, a longitudinally displaceable non-rotating hammer mounted in said casing 13 for movement parallel to the axis of said drive shaft, a cam follower provided on said hammer and riding on said rotating cam to displace said hammer in one direction, an anvil carried by said driven shaft and positioned so as to be contacted by said hammer, a spring mounted between said hammer and said casing and exerting force on said hammer to oppose its displacement by said cam and follower, said spring serving to displace said hammer into contact with said anvil when said hammer is released due to movement of said follower on said cam, and means manually adjustable from the exterior of said casing to vary the initial positions of said cam and follower relative to each other and axially of said drive shaft, said last-named means serving to alter the displacement of said hammer from said anvil due to rotation of said cam.

References Cited in the le of this patent UNITED STATES PATENTS 504,912 Demonet Sept. 12, 1893 1,511,566 Kollock Oct. 14, 1924 1,803,458 Berry May 5, 1931 1,925,289 Strobel Sept. 5, 1933 2,223,727 Homer Dec. 3, 1940 2,556,163 Beeson et al. June 12, 1951