Tool driving or impacting – Means to drive tool about an axis
Patent
1996-07-01
1999-02-09
Smith, Scott A.
Tool driving or impacting
Means to drive tool about an axis
279 193, 279 75, 408226, B23B 5102
Patent
active
058682090
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention proceeds from a device on hand-held tool-driving machines for coupling pounding and/or drilling tools as well as from a tool and tool holder used with that device.
Such a device is known from EP- 433 876 A1, whereby the trapezoidal or rectangular coupling grooves on the tool shank and the corresponding coupling gibs on the tool holder have a limited wear allowance on their coupling flanks. Particularly in the case of tools having a large working diameter and in the case of powerful machines, the lands between the grooves or the gibs in the seating hole of the tool holder break off. Moreover, the rear flank of the trapezoidal or rectangular coupling grooves is loaded by hard torque thrusts, especially in the case of tilted chiseling work, and this results in notch effects that promote breakage of the gibs on the tool holder and of the lands between the grooves on the tool shank.
Furthermore, a chord-shaped recess on the tool shank is known from DE 42 11 533 A1, a recess which lies opposite an essentially trapezoidal groove for coupling. The chord-shaped recess is used for improvement of compatibility in that a tool shank of such a shape can be inserted in hand-held tool devices having coupling gibs of different widths on their tool holders. Coupling in this case, however, is effected is a very one-sided manner, almost solely on the opposite groove's coupling flank located in the drive direction, since the locking bodies of the tool holder absorb only a slight torque in the locking depressions on the tool shank assigned to them.
SUMMARY
In order to achieve a more uniform torque loading of the tool shank and the tool holder, the device of the invention is designed to have besides at least two couplings lying at least approximately opposite to one another an additional coupling with a chord-shaped end on at least one longitudinal side of the tool shank or the tool holder in the circumferential area that lies at least approximately opposite the axial locking feature. As a result of this solution the wear allowance for the tool holder can be advantageously increased and the notch effect on the tool shank reduced or completely avoided by means of the flat coupling in this area. A further advantage lies in the fact that when such tools are clamped in the borehole, for example, this can also be done with maximum loading in reverse gear in the case of overload coupling having impact-like response.
BRIEF DESCRIPTION OF THE DRAWING
Several embodiments of the invention are represented in the drawing and explained in greater detail in the following description.
FIG. 1 shows in cross section in an enlarged representation a tool holder for a drilling hammer with the tool inserted,
FIG. 2 shows a longitudinal section through the front end of the tool holder per II--II in FIG. 1, and
FIG. 3 shows the tool shank. Three additional embodiments of a tool shank designed in accordance with the invention in cross section and the correspondingly designed tool holder are shown in FIGS. 4 and 5, 6 and 7, and 8 and 9.
PREFERRED DESCRIPTION OF THE EMBODIMENTS
The device on tool-driving machines for coupling pounding and/or drilling tools in accordance with the invention, especially on impact drilling machines and drilling hammers or pounding devices, comprises essentially a tool holder 10 that can be driven in the direction of the arrow and a tool shank 11 inserted in it for a tool 12 used for drilling and/or pounding. A cross section through such a device is shown in FIG. 1 as the first embodiment, in connection with FIGS. 2 and 3. The tool holder whose front end is shown in FIG. 2 in longitudinal section forms the end, in a manner known from WO 88/09245 but not shown, of a hollow-cylindrical, driven tool spindle of a drilling hammer into which a riveting set is mounted such that it is axially movable, which set is pounded cyclically by a pounding mechanism of the drilling hammer against the end of the tool shank 1, which is inserted in the seating hole 13 of the tool holder 10. The
REFERENCES:
patent: 4717292 (1988-01-01), Phillips
patent: 5320459 (1994-06-01), Kleine
patent: 5324145 (1994-06-01), Kleine
patent: 5340245 (1994-08-01), Bloechle et al.
patent: 5397203 (1995-03-01), Kleine et al.
patent: 5529444 (1996-06-01), Obermeier
Neubert Heinz
Wierspecker Horst
Robert & Bosch GmbH
Smith Scott A.
Striker Michael J.
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