Tool and chuck for hammer drill

Abstract

A hammer drill has a chuck forming a tool receptacle defining a chuck axis and provided with a tool-holding element radially displaceable into a position protruding into the tool receptacle. The tool has a shank defining a tool axis receivable axially in the receptacle. This shank is formed with a radially outwardly opening recess closed at both axial ends and shaped to receive the tool-holding element, and with an axially extending groove separate from the recess and opening axially at the end of the shank. This groove has at least one flank extending substantially radially of the tool axis. A rotary-entrainment formation in the receptacle is formed with at least one side flatly engageable with the flank for maximum force transmission and minimum wear.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to the commonly assigned and copending patent application No. 574,715 filed May 5, 1975 (now U.S. Pat. No. 3,995,703) the entire disclosure of which is herewith incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a hammer drill. More particularly this invention concerns the combination 11 and the grooves 9 is effected along surfaces extending perfectly perpendicular to the direction that the force is exerted. In addition FIG. 1 shows how the groove 9 is of the same axial length as the ridge 11, insuring a long surface for force transmission between these two formations.

The arrangement shown in FIGS. 3 and 4 is for use with workpieces having shanks 5 with a diameter d equal to more than 10 mm. In this arrangement the recess 7 is identical to that shown in FIGS. 1 and 2, but on the opposite side there is formed a force-transmitting groove 19 with adjacent its base planar flanks 20 identical in function to the flanks 10, but also formed with part-cylindrical surfaces 21 of the same radius of curvature as the recess 7. The dpeth t of the groove 19 is once again equal to 0.2 d. This arrangement can use a ball as shown in FIGS. 1 and 2 or a cylindrical roller with ball-shaped ends to secure it in the chuck 3.

The advantage of the arrangement shown in FIGS. 3 and 4 is that the edges of the recess 19 are substantially less sensitive to damage, so that the corresponding formation 11 will always fit snugly into the groove 19 flatly against the faces 20 thereof.

In FIGS. 5 and 6 a shank 35 is shown which is formed with a pair of diametrically opposite part-cylindrical recesses 27 centered on axes spaced from the shank 25 and lying in a plane perpendicular to the axis A thereof. It is also possible in this arrangement to form the grooves 9 similarly to the grooves 19 of FIGS. 3 and 4.

In FIG. 7 a tool shank 35 is shown having a part-cylindrical section circumferential groove 37 adapted to receive the balls 8 and extending completely around the shank 35. This groove 37 is of a depth less than the depth of the grooves 9. This arrangement is, once again, provided with two torque-transmitting grooves 9 of trapezoidal section. Such an arrangement is able to transmit considerable rotational forces between the chuck and the shank 35. It is also possible in this arrangement to provide two further grooves 9 offset by 90° to the grooves 9 shown in FIG. 4 so that four formations can be used to transmit force between the chuck 3 and the shank 35.

The arrangement shown in FIG. 9 is identical to that shown in FIGS. 3 and 4 except that here surfaces 21 are provided which are planar rather than part-cylindrical.

In FIG. 10 a shank 45 is shown which has on one side a recess identical to the recess 7 and on the other side a recess 39 formed as two trapezoidal-section grooves having outer flanks 40 and separated by an intermediate ridge 42 that does not extend all the way out to the outer circumference of the shank 45. In addition, the flanks 40 are beveled off at 41 much as shown in FIG. 9 so that slight damage to the outer part of the shank 45 will not prevent a correspondingly shaped ridge from fitting into the double groove 39 snugly in contact with the intermediate ridge 42 and flanks 40 thereof.

Finally, FIG. 11 shows a shank 55 which is adapted to be rotated in a direction 56. This shank 55 is formed with a pair of diametrically opposite recesses 7 and a pair of diametrically opposite recesses 19 identical to those shown in FIGS. 3 and 4 and having surfaces 57 corresponding to the surface 20 in FIGS. 3 and 4. In this arrangement, however, each of the grooves 19 lies in the direction of rotation 56 at an angle α offset from the corresponding recess 7. This angle α is equal to 60° and ensures that relatively wide webs are provided on the bearing sides of the grooves 19 for maximum force transmission between the chuck 3 and the shank 55. Such an arrangement has been found to have an extremely long service life and to be able to transmit enormous torque.

With the tools according to the present invention it is therefore possible to obtain a service life which is a multiple of the service life normally obtained by bits in a hammer drill. Indeed it is possible to use the tool until its working end is completely worn away, whereas in normal situations the shank often wore out before the working tip did.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of structure differing from the types described above.

While the invention has been illustrated and described as embodied in a hammer-drill arrangement, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. In a combination with a chuck having a tool receptacle defining a chuck axis, a rotary and impact tool having a shank defining a tool axis and receivable in said receptacle; cooperating means on said shank and said receptacle for retaining said tool in said receptacle against extraction therefrom while permitting axial displacement of the tool relative to the receptacle so that the tool can transmit axial impact to a workpiece; and means separate from said cooperating means and operative for transmitting torque between said chuck and said tool, including an axially extending groove separate and circumferentially spaced from said cooperating means, said groove being axially open at the end of said shank and having at least one flank extending substantially radially of said tool axis, said torque transmitting means further including a rotary-entrainment formation in said receptacle formed with at least one side flatly engageable with said flank.

2. The combination defined in claim 1 wherein said groove has a pair of such flanks both being coplanar with said tool axis.

3. The combination defined in claim 2 wherein said formation has an axial length substantially equal to the axial length of said groove.

4. The combination as defined in claim 1, wherein said cooperating means includes a radially outwardly opening recess formed in said shank and closed at both axial ends of said recess, and a tool-holding element radially displaceable into a position protruding into said receptacle so as to be received into said recess.

5. The combination defined in claim 4 wherein said shank is of regular section, said recess extending circumferentially completely around said shank and through said groove.

6. The combination defined in claim 4 wherein said shank is generally cylindrical and has a predetermined diameter, said groove having a radial depth equal to between three-twentieths and one-quarter of said diameter.

7. The combination defined in claim 4 wherein said groove and said recess lie on diametrically opposite sides of said tool axis.

8. The combination defined in claim 4 wherein said tool-holding element has a round inner end and said recess is similarly of rounded shape complementary to that of said inner end.

9. The combination defined in claim 4 wherein said shank is formed with two such recesses on diagonally opposite sides and with two such grooves also on diagonally opposite sides but angularly offset from said recesses.

10. The combination defined in claim 9 wherein said grooves are offset angularly relative to said tool axis from said recesses by between 45° and 90°.

11. The combination defined in claim 1 wherein said groove is of prismatic shape.

12. The combination defined in claim 11 wherein said shank has two such grooves on diagonally opposite sides.

13. The combination defined in claim 11 wherein said recess is of part-cylindrical shape and said groove is formed in the base of said recess.

14. In a power tool, a combination comprising a chuck having a tool receptacle defining a chuck axis; a rotary and impact tool having a shank defining a tool axis and being receivable in said receptacle; cooperating means on said shank and said receptacle for retaining said tool in said receptacle against extraction therefrom while permitting axial displacement of the tool relative to the receptacle so that the tool can transmit axial impact to a workpiece; and means separate from said cooperating means and operative for transmitting torque between said chuck and said tool, including an axially extending groove separate and circumferentially spaced from said cooperating means, said groove being axially open at the end of said shank and having at least one flank extending substantially radially of said tool axis, said means further including a rotary-entrainment formation in said receptacle formed with at least one side flatly engageable with said flank.

15. A rotary and impact tool for the use with a chuck having a tool receptacle, a first formation in the receptacle and a projection in the receptacle separate from the first formation, the tool comprising a shank defining a tool axis; a second formation on said shank and cooperating with the first formation of the chuck so as to form together cooperating means for retaining the tool in the receptacle of the chuck against extraction therefrom while permitting axial displacement of the tool relative to the receptacle whereby the tool can transmit axial impact to a workpiece; and an additional formation on said shank and formed as an axially extending groove which is separate and circumferentially spaced from said second formation, said groove being axially open at the end of said shank and having at least one flank extending substantially radially of said tool axis so that the projection of the chuck can engage in said groove and at least one side of the projection can flatly engage with said one flank, whereby said groove of said shank and the projection of the chuck together form means which is separate from the cooperating means and operative for transmitting torque between the chuck and the tool.

16. A rotary and impact tool as defined in claim 15, wherein said second formation of said shank is arranged so that it is in direct contact with the first formation of the receptacle of the chuck without interposition of additional means. 17. A rotary and impact tool as defined in claim 15, wherein said one flank of said groove of said shank is arranged so that it is in direct contact with the projection of the chuck without interposition of additional means. 18. A rotary and impact tool as defined in claim 15, wherein said second formation of said shank is formed as a concave recess which is closed at both its axial ends. 19. A rotary and impact tool as defined in claim 15, wherein said second formation of said shank is formed as a recess having a part-cylindrical cross section and two part-spherical axial ends. 20. A rotary and impact tool comprising a shank defining a tool axis; a formation on said shank allowing limited axial displacement of said shank so that the tool can transmit axial impact to a workpiece and at the same time preventing complete axial extraction of said shank from a holding structure; and an additional formation on said shank and formed as an axially extending groove which is separate and circumferentially spaced from said first-mentioned formation, said groove being axially open at the end of said shank, having at least one flank extending substantially radially of said tool axis and being operative for transmitting torque to said shank. 21. A rotary and impact tool as defined in claim 20, wherein said first-mentioned formation on said shank is formed as a concave recess

which is closed at both its axial ends. 22. A rotary and impact tool as defined in claim 20, wherein said first-mentioned formation on said shank is formed as a recess having a part-cylindrical cross section and two part-spherical axial ends.