US 3268014 A
Description (OCR text may contain errors)
Filed April 1964 INVENTQ Ambrose W Drew ATTORNEY.
r 3,268,014 [Ce Patented August 23, 1966 Filed Apr. 17, 1964, Ser. No. 360,719 3 Claims. (Cl. 17397) This application is a continuation-in-part of application, Serial No. 251,180, filed January 14, 1963, now Patent 3,149,681.
This invention relates generally to tools and is more particularly concerned with a rotary hammer device for simultaneously rotating and axially impacting a tool bit and other member.
Conducive to a better understanding of the invention, it may be well to point out that tools of this type have a common defect in that they are subject to excessive heating, due to friction generated between the impacting elements which comprise a rotating anvil portion against which a non-rotating hammer is repeatedly driven. Since the anvil and its shaft are ordinarily operated at speeds of 1800 r.p.m., it will be evident that even during the short period of impact there is a substantial frictional drag between the stationary and rotating parts.
To reduce the heating effect, various schemes of lubrication, cooling air circulation, and heat dissipating fins have been used.
The primary object of this invention, therefore, is to provide a rotary impact hammer whose anvil and hammer elements rotate together and impact, without relative rotation, in friction free engagement.
Another object is to provide a device of the type stated whose tool holding element is free to move axially of its center of rotation under impact.
A further object is to provide a rotary hammer mechanism for rotating a drill bit, or the like, and simultaneously applying frictionless axial impacts thereto, which device is simple in construction, fully adjustable as to the force of the delivered impact, heat free in operation, and relatively inexpensive to manufacture.
With the foregoing and other objects in view which will appear as the description proceeds, the invention resides in the combination and arrangement of parts and in the details of construction hereinafter described and claimed, it being the intention to cover all changes and modifications of the example of the invention herein chosen for purposes of the disclosure, which do not constitute departures from the spirit and scope of the invention.
The invention is illustrated in the accompanying drawing, wherein:
FIGURE 1 is a longitudinal sectional view of the rotary hammer device.
FIGURE 2 is a longitudinal sectional view of an alternate form of the device.
FIGURE 3 is a horizontal section on line 33 of FIGURE 2.
FIGURE 4 is a side elevation of the hammer portion shown in FIGURES 2 and 3.
By referring to the drawing, and FIGURE 1 in particular, it will be seen that the rotary impact hammer that is the subject of this invention is adapted to be mounted on a conventional portable electric drill case having a shoulder and a motor drive shaft 11.
An elongated, hollow housing 12 is mounted on the shoulder 10 through a collar 13, which is fitted over the shoulder 10 and clamped thereon by means of a bolt 14.
The housing 12 is threaded at its forward end 15 and a cam cap 16, having internal threads, is mounted on the housing threads and rotatable thereon. The cap 16 has a centered hole 17 therethrough.
A cam ring 18 is mounted inside the cap 16 by means of screws 19. The cam ring 18 also has a central bore 20 surrounded by a series of sharply inclined and spaced cam teeth 21 rising to an abruptly vertical end face 22. A rotating axially movable spindle 23 is mounted on the threaded end of the motor drive shaft 11, through a coupling sleeve 24 so as to form a continuation thereof. A bearing 25 serves as a journal supporting the sleeve 24 in the housing 12. The spindle 23 extends through the housing 12 and beyond the end cap 16. The cam ring 18 has a shouldered secondary bore which holds a bearing unit 26 which supports the spindle 23 in the housing 12 adjacent the end cap 16. The coupling 24 has a bore 27 therethrough which is threaded at one end to engage the threaded end of the motor drive shaft 11 as heretofore described, and the other end of the sleeve 24 has a diametrical slot 28 cut thereacross.
The free end of the spindle 23 is threaded as at 29 to receive a tool holding device, such as a drill chuck, not illustrated.
A secondary coupling sleeve 30, having a diametrically disposed upstanding key 31 which mates with slot 28 of the coupling sleeve 24, is mounted on the spindle 23, which extends therethrough in a free sliding fit.
The secondary coupling sleeve 30 has a pair of aligned longitudinally extending slots 32 cut through the walls thereof, which are engaged by a pin 33 mounted through the spindle 23 and which acts to lock the sleeve 30 and spindle 23 against relative rotation but leaves the spindle 23 free to reciprocate axially in the sleeve within the length of the slots 32.
It will be seen that there is no direct connection between the spindle 23 and the motor drive shaft 11, so that the spindle 23 is free to reciprocate in the two coupling sleeves 24 and 30, toward or away from the drive shaft 11.
The spindle 23 has an anvil 34 thereon adjacent the end face 22 of the cams 21 and the anvil 34 may be either formed integral with the spindle 23 or may be a separate piece, immovably mounted thereon. The anvil 34 is located within the counter bore 20 of the cam ring 18.
The cam ring 18 has four cam track teeth 21 thereon.
A hammer 35 is slidably mounted, through a central bore 36, on the spindle 23, inwardly of the cam ring 18. The hammer has four cam follower balls 37 embedded therein which operate co-operatively with the teeth 21 of the cam ring 18. An annular head is formed on the hammer 35 faced toward and aligned with the anvil 34. An elongated slot 38 cut through the opposed walls of the hammer 35 is engaged by a pin 39 mounted through the spindle 23. The pin 39 acts to lock the hammer and spindle against relative rotation, but leaves the hammer 35 free to reciprocate longitudinally of the spindle 23, the length of the slots 38.
The hammer 35 is normally biased toward the anvil 34 and in contact with the cam teeth 21 'by a spring 40 anchored at one end in a groove 41 in the coupling sleeve 30 and seated at its other end in a second groove 42 in the hammer 35.
It will now be evident that the anvil 34 and the hammer 35 rotate with the spindle 23 and at the same speed as the spindle. As a result, when the hammer 35 is impacted against the anvil by the co-operative action of the camming components together with the biasing action of the spring 40, there is no wiping or sliding action between the anvil and hammer to create friction. Therefore, the device will remain'cool even after prolonged operation.
Since the spindle 23 is slidably mounted through the coupling sleeve 30, at the moment of impact, the spindle 23 and anvil 34 are free to move axially away from the hammer 35 to carry the tool retained on the spindle end 29 forward in the direction of the impact blow, thereby providing a true hammer impact.
It will occur to those skilled in the art that modifications of the structure just described are sometimes desirable, and one such modification incorporating advantages as hereinafter set forth may be seen, as by referring to FIGURES 2, 3, and 4 of the drawings.
In FIGURE 2 of the drawings, a portion of a case 44 of a portable electric drill may be seen and which case is provided with a threaded shoulder 45 surrounding a drive shaft 46 and spaced with respect thereto by a bearing assembly 47. The alternate form of the rotary hammer device is attached directly to the threaded shoulder 45 and comprises an elongated hollow housing 48 threaded at one of its ends for engagement with the threaded shoulder 45 of the portable electric drill.
The opposite end of the housing 48 is closed with the exception of a central opening 49. A coupling sleeve 59 has a threaded socket 51 in one end thereof which is threaded for engagement on the drive shaft 46 of the motor, and the other end of the coupling 59 has a bore 52 therein for the reception of one end of a spindle 53. A slot 54 is formed in the spindle 53 and a pin 55 is positioned transversely of the sleeve 50 and through the slot 54 so that the spindle 53 may move axially relative to the sleeve 50. A bearing assembly 56 is mounted in the end of the housing 48 adjacent the opening 49 and journals the spindle 53, and it will be seen that this construction hglds the spindle in desired axial position of the housing 4 An anvil 57 is formed on the spindle 53 inwardly of the bearing assembly 56 and within the chamber 58 in the housing 48 as defined by an annular sleeve 59 which is secured in position by set screws 60'. The annular sleeve 59 has oppositely disposed openings 61 therein which partially cage the balls 62 for relative rotation. A hammer 63 having an axial bore 64 therethrough is positioned on the spindle 53 in spaced relation to the anvil 57 and includes a striking face 65 which is adapted to be moved in a reciprocal motion relative to the anvil 57 so as to impart hammer-like blows thereto when the spindle 53 and the hammer 63 are revolved.
A secondary slot 66 transversely of the hammer 63 engages a pin 67 positioned through a spindle 53 so that the hammer 63 may move within the limitations of the slot 66. A coil spring 68 is positioned between the hammer 63 and the coupling 50 and normally biases the hammer 63 toward the anvil 57. The hammer 63 has a pair of cams 69 formed thereon in oppositely disposed relation with interconnecting camming surfaces 70 and the area of the hammer 63- between the earns 69 and the striking face 65 is of a reduced diameter so that the balls 62 which comprise cam followers will engage the annular area of the hammer 63 beyond the earns 69 and simultaneously engage the cams 69 and the intermediate camming surfaces 70.
It will thus be seen that rotation of the spindle 53 by the motor in the portable electric drill will rotate the hammer 63 relative to the balls 62 which comprise cam followers and that the hammer 63 will therefore be moved in a reciprocal hammering action relative to the anvil 57 and the spindle 53 due to the biasing of the coil spring 68.
It will further be seen that the distance of movement may be varied by varying the height of the cams 69 so that maximum hammer blows are obtained on the anvil 57.
In FIGURE 3 of the drawings, a cross section on line 33 of FIGURE 2 illustrates the balls 62 which comprise cam followers in position adjacent the earns 69, and in FIGURE 4 of the drawings a side elevation of the hammer 63 and a portion of the spindle 53 on which it is mounted may be seen with the cams 69 and camming surfaces in plan view.
It will occur to those skilled in the art that the particular construction disclosed herein is particularly suitable in a torque wrench of the impact type.
It will thus be seen that an improved alternate construction has been disclosed which provides for a remarkably increased striking distance of the hammer with respect to the anvil as compared with the form of the invention illustrated in FIGURE 1 and heretofore described.
It will thus be seen that the rotary hammer disclosed herein meets the several objects of my invention, and having thus described my invention, what I claim is:
1. In combination with a portable electric drill of the type having a case and a drive shaft protruding therefrom, a rotary impact hammer, comprising, an elongated hollow housing mounted on the case at the drive shaft; a spindle journaled in the housing for rotary and limited axial movement relative to the housing and extending through the forward end thereof, the spindle having tool holding means at its outer end; coupling means on said spindle, within said housing, for connection to the motor drive shaft; anvil means comprising a shouldered collar positioued on the spindle intermediate its ends; hammer means slidably mounted on and keyed to the spindle for rotation therewith and movement axially thereof between a first position, in engagement with the spindle anvil, and a second position, spaced from the anvil; spring means mounted on the spindle in pressed egagement with the hammer for normally biasing the hammer to its first position; said spindle anvil being movable between a first and second position, the spindle anvil being clear of the hammer when the spindle anvil is in its first position; and co-operating cam means on said hammer and housing for alternately moving the hammer between its first and second positions for imparting impact to the spindle anvil along its axis of rotation when the spindle is rotated in the housing and the spindle anvil is moved to its second, retracted position, against the biasing action of the spring, by reason of inward pressure by the held tool exerted against the spindle and; said co-operating cam means comprising a plurality of circumferentially arranged carnming portions on an annular shoulder of the hammer, and rotating therewith, and a plurality of e c-operating, circularly arranged rotatable cam engaging portions on the housing and held thereby.
2. A rotary impact hammer for use with a portable electric drill having a case and a drive shaft protruding therfrom comprising an elongated hollow housing arranged for attachment to said case at one end, a spindle journalled in said housing for rotary and limited axial movement relative to said housing, detachable coupling means on said spindle engaging said drive shaft, a cylindrical hammer slidably mounted on said spindle, means on said spindle engaging said hammer arranged to permit reciprocal movement of said hammer on said spindle, an anvil on said spindle spaced relative to said hammer and positioned for engagement by said hammer, spring means on said spindle biasing said hammer toward said anvil, circumferentially arranged interconnecting cam means on said hammer, an apertured sleeve received in said housing, rotatable cam followers positioned in said apertured sleeve for registry with said cam means.
3. A rotary impact hammer for use with a portable electric drill having a case and a driveshaft protruding therefrom and comprising an elongated hollow housing arranged for attachment to said case at one end, a spindle journalled in said housing for rotary and limited axial movement relative to said housing, detachable coupling means on said spindle engaging said driveshaft, a cylindrical hammer slidably mounted on said spindle, means on said spindle engaging said hammer arranged to permit reciprocal movement of said hammer on said spindle, an anvil on said spindle spaced relative to said hammer and positioned for engagement by said hammer, spring 5 6 means .on said spindle biasing said hammer toward said References Cited by the Examiner anvil, circumferentially arranged interconnecting cam UNITED STATES PATENTS means on said hammer, an apertured sleeve in said housing, rotatable cam followers positioned in said apertured 2,293,443 8/1942 Mossberg 173 119 sleeve for registry with said cam means on said hammer, 5 2,492,840 12/1949 Bugg 17395 said hammer comprising a solid cylindrical member having 3,123,156 3/ 1964 Gapstur 1731 19 two different outer diameters forming a larger portion FOREIGN PATENTS and a smaller portion thereof and wherein said cam means on said hammer are formed on the larger portion ad- 564,001 9/ 1944 Great Brltallh jacent the smaller portion, said smaller and larger por- 10 I tions of said hammer being telescopically engaged in said MILTON KAUFMAN 1mm y Examiner apertured sleeve and movable axially relative thereto. LAWRENCE P. KESSLER, Examiner.