US2259807A - Rock drill - Google Patents

Description

- Oct. 21, 1941.

ROCK DRILL Filed July 18, 1939 3nventor Thomas J-Edwards 1w Brede Knudsen t orneg T. J. EDWARDS ET AL- 2,259,807

2 Sheets-Sh'eet 1 7 4 T. J. EDWARDS ETAL 2,259,807

nocx DRILL 2 Sheets-Sheet 2 Filed July 18, 1939 Thdmas J- Edwcl B rede K Patented Oct. 21, 1941 Thomas J. Edwards, near 1 Seattle, and 'Brede Knudsen, near Monroe, Wash.

' hpplicationiuly 18', 1939, 'Serial Nc. 285,056 I 4 Claims. (Cl

been a great deal of seemingly unavoidable com- Our invention relates to percussion drills, intended primarily for rock drilling, and particularly to percussion drills of the type in which a rapidly rotating hammer, having impact elements projecting outwardly from a, surface, lengages complemental impact elements upon a striker which is in striking engagement with the end of the drill shank, thereby to effect rapid vibratory reciprocation of the drill shank in'the direction of its length. I

Such devices, as heretofore proposed, have been of two general types. In one such type the hammer is retracted by cam means, in opposition to a stiff spring, and is suddenly released; the hammer, when released, advances towards and strikes the striker with a force that is dependentprimarily upon the stored forcejof the spring thus suddenly released. In the second type a rotative hammer element is engaged by the striker element, which is rriovable-with relation to the hammer element, the hammer and the striker each having impact elements upstanding from their adjacent surfaces, some} timesof hardened ball or roller for-m, whereby with each impact the striker is repelled and the drill bit through a workcaused to advance ins stroke; the force of each drill stroke is" a function primarily of the rapidity of the'striking impact. The latter type of drill, as heretofore employed, relies primarily upon' very rapidly repeated light blows,rather thanjlpor less i r'fequent but heavier blows. 4 Certain objections have been encountered practical operation of each of these types. In

the first type, wherein the impact is'ipr'oduc'ed by plexity, both in the tool itself and in its adjuncts, for instance in devicesfor supplying water to and through the hollow shankof thedr'ill bit, thereby renderin such tools complicated and;

- expensive.

One of the primary objects of the present in: vention is to simplify the structured-f such tools and thereby to make them extremely ruggedand far better suited to the conditionsunder which they will see service; This end is achieved in part by elimination of parts, and in part by ma terially increasing the mass of thehamm'erfas compared to the mass of ther'emainingpar't's.

It is a further object to provide such a tool in which the force of the'impact', or'theeffective the release of energy stored in a spring, the I spring is liable to break in time, because of fatigue of the material, and during 'operation it has a certain inherent periodicitywhich to some extent limits the periodicity of the vibrations and the force of the impact. Neither is it possible, with ease or certainty, to vary the force of the blows. In the second type, which involves rapidly repeated impacts between impact elements on the rotative hammer and on the rec'iprocative striker, perhaps in an attempt to lighten the tool, the hammer is of no large mass, and'the weight of the blow it strikes is thereforelargely or primarily dependent upon the weight,not of the hammer alone, but of the entire tool, which is itself and in its entirety set into rapid vibration by the repeated impacts. As mentioned, reliance for effectiveness is placed upon repeated light blows, rather than upon heavy blows. In both such types as heretofore proposed there has ness of the drill, is in "nowise'controlled by'the stored force of a spring, nor primarily by rapidity of impact,but"pi-imarily by the greater mass of the hammer initiating the impact as 'com-' pared to the impacted parts 'of'the tool;

It'is a further object of the invention to provide such a tool which may'incorpdrate the desirable features'of prior devices, siich as antifriction rollers or balls, arota'tive chuck or drill support, and water supply means, but which will be materially simplified and improved in the respects indicated above.

It is a further object to provide such a tool in' which, at will and by simple means, it is possible to accomplish rotation of the bit intermediate each working stroke to a new position, or to per-- mit' the "bit to remain with'ou'trotation. J

it is a further object to provide such a drill, the principles whereof may be adapted to a' tool in which the hammer and the striker are in axial alignment, or to a tool in which the hammer and the striker are disposed with the axis of one transverse to'the axis of the other.

With these and other objects in mind, a will appear hereafter, our invention comprises the novel parts, and the novel combination and arrangement thereof, as shown'in the accompany-- ing dr'awings, described in this specification, and as will 'be more particularly defined'by the claims which terminate the same.

In the accompanying drawings we have shown our invention embodied in forms which are at presentipreferred by us, it being understood that various changes may 'bemade in the form; char-' acter, and arrangement of parts, within the scope of the invention as hereinafter defined by the claims. 4

Figure l is in general an axial section through a typical form of ourdevicafandFigure 2 is a shank of the drill bit 4 is supported. Thus supported, the end of the drills shank engages, and

is engaged by, the striker 2, and the latter is y guided for movement towards and from a surface of the hammer I, whereby impact elements.

H upon the hammer engage complemental impact elements 2| upon the striker to effect re-.

ciprocation of the striker 2 and of thedrill 4 which is in engagement with the striker. urally it is necessary to provide a suitable sup-' port for thethree essential elements, whichsupport should be common'to all of them, and to this end there is provided a casing 5,within which the hammer l is;journaled, the'chuck 3 is rotatively held, and the striker 2 is guided for movement in a direction'lengthwise of the drills shank. Preferably the striker is not permitted to rotate, and to this end a key 52 is held within the casing and engages within a keyway 25 in the striker. Since it is desirable thatthe drill support 3 be permitted to rotate,"it is supported in rotative bearings 35 within the casing 5. The hammer l is likewise rotatively supported within the casing, and in the form of Figure 1 its axis of rotation is transverse to the axis of'the drill shank 4, and hence it is supported by trunnioned ends H1 in radial bearings 55. -In the form shown in Figure 3 the hammer I is rotative about an axis which c'oincideswith the axis of the drills shank, therefore it must be provided with end thrust bearings 54, which may-also take radial thrust, or which may be supplemented with additional radial bearings 55.

Insofar as certain functions, accomplishments and advantages of the invention are concerned, the impact elements II and 2|.mi ht take vari-' ous forms. They might be, for instance, mere- 1y outstanding impact cams, raised above the adjoining surfaces of the hammer and of e the striker, and incapable of movement each relative to its supporting member. They may also be in the form of balls, as shown at H and at 2| in Figures 3 and 4, or as shown at H and 2| in Figures 1 and 2, they may take the form of rollers. While cylindrical rollers are shown, other forms may be employed. The supporting member in each case is provided with apocket for the reception and retention of each such im-. pact element. while pocket and element are of such shape that the element may roll relative to the member which supports it, to present a fresh point or line of contact with each sucopposing deflection from a given position, and relatively speaking, the striker 2 and drill 4 have materially less inertia resisting departure from a given position. The result is that the hammer strikes an actual blow with each impact, and repels the striker 2 and drill 4 through the impact engagement of the elements II and 2!, or II and 2|, yet because of the simplification of the device, through omission of intricate or unnecessary parts, and through the omission of springs, the device as a whole is not of such great weight but what it can be carried about and used without undue difliculty. In particular it should be noted that because the inertia of the massive hammer absorbs the greatest part of the shock of impact, that shock is not transmitted undulytothe device as a whole. and the Nat-' latter does not vibrate with undue intensity. As a result a workman, supporting the device, as for: instance by the handles 53, is not unduly fatigued byrapid vibration, of appreciable amplitude, the amplitude of vibration of the striker and drill being much greater than that of the hammer and casing because of the large inertia of the hammer.

It is desirable, after a hole is started, indeed necessary, to rotate the working point 46 of the drill bit to a fresh position frequently or substantially continuously. However, in starting a holeit is preferable that the working point be not permitted to rotate, in order that it may achieve a start and-not wander over the face of the work. The present invention, in either form, is designed to accomplish either of these ends at will and by a simple adjustment.

- Since it is necessary to allow the drillto be handled in use, hence to keep its total weight within reasonable bounds, notwithstanding the massive hammer, it is preferred to employ means other than a self-contained motor to effect the necessary rotation of the hammer. Thus there is provided a coupling at for a flexible drive shaft 6 or like means, extending from a distant motor (not shown). Journaled at 6|, within the casing or generalsupport 5, is a two-part jack shaft, the two parts being illustrated at 62 and 63. The, part 62 is always in connection with the drive shaft 6 through the coupling 66, and carries a gear which meshes with a complemental gear upon the hammer I, whereby the latter is rotated. In the form shown in Figure 1 the meshing gears 64 and I6 are bevel gears, whereas: in Figure 3 the corresponding gears 64' and I6 are spur gears.

The two parts of the jack shaft are capable of being clutched together for conjoint rotation by simple clutch means. In the form shown in Figure 1 a clutch element 65, splined upon the live shaft part 62, is provided with a tapered cessive impact. Any suitable means to this end v 7 may be employed, such means being already known in the art.

It is desired to point out here that the hammer I is of large mass with respect to thestriker and drill. The hammer, for instance, may weigh 50 pounds, of a total weight of perhaps 125 pounds for the entire device; in other words, the mass of the hammer represents a large proportion, preferably about 40%, as in the example given, of the whole mass. The striker 2 and drill 4 combinedbeing of materially less mass than the hammer, the hammer has large inertia socket engageable with a tapered tip 66 on the second part 63 of the jack shaft, and is urged into engagement by-a spring 61. A sleeve 68 threaded at 56 in the general support 5, within and relative to which clutch element 65 rotates,

serves to control engagement or disengagement of the sleeve 65 and tip 66. The sleeve 65 effects rotation of the part 63 when the tapered clutch elements are engaged by downward screwing of sleeve 68, and when such sleeve is sufficiently raised by unscrewing it these clutch elements are positively separated by pressure of sleeve 68 against the flange of sleeve 65, compressing spring 61, so that it rotates freely without driving shaft 63. In the form shown in Figure 3 the tapered tip 66 is carried upon the live jack shaft pm 62, and the part 63' is provided with a templemental socket, engagement being accomplished by threading of the sleeve-68', within and relative to which shaft 62-rotates into the general support 5. Unscrewing movement "of sleeve '68 lifts tipfBG positively out ofengagement'with its socket in shaft 63, so that its driving connection is interrupted. 1 J I In each form of the device the disconnectible jack shaft part 63 isprovided with a driving gear 69, whichmeshes at all times with a gear 36 carried'by the chuck ordrill support 3; Wh'e n'ever the part 63 is connected with the drive the chuck 3 is causedto rotate positively, 3 When the' pa'rts 62 and 63 are disconnected the 'chuck'3 will-not normally .rotate.'- It is desired to point outthat it is given no impulse to rotate by the striker, since thelatter is held against rotation, and may only reciprocate in the direction of the length of the shank of the drill bit.

Itis desired to point out also that the ratio between the gears 69 andfi is such, with respect to the ratio between the gears 64 and It, or 64' and I6, that the chuck 3 is rotated at a rate considerably slower than the hammer is rotated, which is desirable.

It is necessary, during rock drilling operations, to supply water adjacent the working tip 40 of the drill bit, and to this end the drill is provided with a central bore 4|, and with outlets adjacent the point 40, which latter are not shown. Since the device as a whole is intended to be portable, Water must be supplied through a flexible connection, and guided, through conduits incorporated within the device, to the hollow bore 4!. The form shown in Figure 3 is particularly adapted to doing this, in that the rotative hammer I is coaxial with the striker 2 and with the drill 4, and therefore the water, supplied at 10, opposite the drill bit 4, may be supplied through a conduit 1, which passes through the axis of the hammer I, through the striker 2, and its tip H may enter and be reasonably well packed within the bore 4|. No interference with working parts is thereby entailed in any way, nor is there likelihood of intermingling of water and lubricant contained within the chamber of the casing 5. In the form shown in Figures 1 and 2 the same result can be accomplished by bending the conduit l, as indicated at 12 in Figure 2, so that I it passes around the transversely disposed hammer I. The bend 12 may indeed embrace the hammer I much more closely than is illustrated, and without danger of efiecting vibration or wear of the conduit by direct contact with the hammer, by reason of the fact that the hammer l, due to its relatively great mass, has no appreciable tendency to vibrate. In the latter form the impact elements H need not extend the entire length of the cylindrical periphery of the hammer I, but may be divided, as also the impact elements 2|, whereby to afiord space for the bend 12 between the divided impact elements, as is best seen in Figure 1.

The number of such impact elements, and consequently the number of impulses for each rotation of the hammer, is a matter which may be varied as desired. By employing the form shownin Figures 1 and 2 the surface of the hammer which carries such impact elements is increased, over the surface available in the form shown in Figures 3 and 4, and consequently more such impact elements may be employed in that surface, and more impacts may be obtained for each revolution of the hammer. By such an expedient the r ateof rotation of the hammer may be lessened withoutlessening-the number of impacts in aigivenpenod or time."-

It is -desi red to- :point out What is true in this arrangement, as in othersimilar arrangements, namely,' 'that the force of each impact depends substantially entirely upon the-degree to which the impact elements 2 are moved, by pressure upon the working poi-nt -of the drill and transmitted through the- -dr ill to the striker, into the path of the impact element's l1.v If the impact elements2l only-barely"enter the path of the elements H then the force of each impact is but slight. If the=elements 2i are pressed moredeeplyinto the path ofnthe elements ll,'the force of each impact will be greaterQand this is a matter which;is wholly within the control of the operator, for he can transmit more or less pressure or-resistance from the point 40 'to the impact elements II, and thereby control or vary the force of the 1 1 128 01? from very light impact tothemaximum permitted by the mass and-rate of rotation of the hammer. It is desired also to point out that there are a minimum number of parts, and each part is rugged and substantial, and practically impossible to wear out, other than perhaps the hardened impact elements, which can be readily replaced, if necessary. In particular there are no springs which are necessary to the hammering operation, and consequently there is no possibility of placing the drill as a whole out of operation, due to a defect in or breakage of a spring. Because of the ruggedness and simplicity of the machine as a whole, superfluous parts may be eliminated, and though the hammer itself is of very large mass, and constitutes a large part of they total weight, the weight of the device as a whole is yet within reasonable bounds, and it can be transported and moved about in operation with all the facility required, and fatigue upon the operator is lessened by elimination, to a large degree, of vibration at the supporting handles.

What we claim as our invention is:

1. A percussion drill comprising, in combination with a casing having means to support a drill bit for vibratory movement in the direction of its length, a cylindrical rotative hammer, supported in said casing, the axis whereof is disposed transversely of the drill bits shank, a centrally bored striker disposed withinthe casing to be engaged by the drill bit, and guided therein for movement under the pressure of the drill bit towards the axis of the hammer, upstanding impact elements carried by the adjacent faces of the hammer and striker, in position for engagement by such movement of the striker, upon engagement to repel the striker, and a water supply conduit entering the casing at the sid opposite the drill bit, extending about th hammer, and entering the central bore of the striker, to be conducted, via a bore along the drill shank, to the working tip of the drill bit.

2. A percussion drill comprising a casing, means rotatively supported thereby for supporting a drill bit for vibratory reciprocation in the direction of its length, a rotative hammer journaled in the casing, and disposed with its axis transversely of the drills shank, and in a plane common thereto, a striker guided within the casing against rotation, and for movement, in the direction of the length of th drills shank, towards and from the hammer under the pressure of the drill shank engaged therewith, comadjacent surfaces of the hammer and striker, in

position for engagementmoreor less in accordance with the extent of the advance of the striker towards the hammer, by such engagement being repelled to eifecta working stroke of the drill bit, a two-part jack shaft journaled in the'casing, parallel to the drills shank, drive means to rotate one part of the jack shaft, a positive driving connection between itsother part and the rotative drill-supporting, means, and clutch means for operative engagement or disengagement of its two parts, at will.

3. A percussion drilling machine comprising a casing, a. rotatable hammer therein, a striker mounted in said casing for unrestrained reciprocable movement, means for reciprocally mounting a drill bit in a position to be struck by said striker, and means whereby rotation of said hammer imparts blows to said striker to be transmitted by the latter to the drill bit, the weight of the hammer being approximately forty per cent of the weight of the complete machine including the drill bit when the drill bit is of a weight approximately midway between the I Weights of the heaviest and the lightest drill bits which the machine is designed to use, whereby vibration of the drilling machine is largely absorbed by the hammer.

4. A percussion drilling machine comprising a casing, a rotatable hammer therein, a striker mounted in said casing for unrestrained reciprocable movement, means for reciprocally mounting a drill bit in a position to 'be struck by said striker, and means whereby rotation of said hammer imparts blows to said striker to be transmitted bythe latter to the drill bit,the weight of the hammer being at least forty per cent of the weight of the complete machine including the drill bit when thedrillv bit is of a weight approximately 'midway between the weights of the heaviest and the lightest drill bits which the machine is designed to use, whereby vibration of the drilling machine is largely absorbed by the hammer.

THOMAS J. EDWARDS. BREDE KNUDSEN.

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