Chucks or sockets – Socket type – Lost motion
Patent
1989-11-20
1991-07-02
Bishop, Steven C.
Chucks or sockets
Socket type
Lost motion
279 75, 408 16, 408226, B23B 3122, B23B 5102
Patent
active
050280570
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is related to a device on hand machine tools.
Such a device is already known from DE-PS 25 51 125. Tools constructed according to this patent are also usable in principle in tool receptacles provided according to AT-PS 285 405, wherein the locking elements applied in the latter engage in the recesses which are closed on both sides and arranged in the tool shaft outside the rotary driving grooves. The width and depth of the rotary driving grooves opening out at the end of the tool shaft are selected in such a way that they can not receive the locking elements, and accordingly the tool can not be incorrectly inserted.
However, particularly in severe construction site operation, the rotary driving grooves can become worn out after long use of the tool to such an extent that the tool can unintentionally be inserted into the tool holder in a position in which the locking elements engage in the rotary driving grooves. This brings about the risk that the machine may be unexpectedly disengaged from the tool when withdrawing the machine from the workpiece during operation, since the locking elements of the tool receptacle can slide out of the rotary driving grooves, which are open toward the end of the tool, in an unimpeded manner. This is particularly dangerous because when working with the machine the operator can not determine in certain cases that the tool is incorrectly inserted. In this case, the operator will only notice it--but in an entirely unanticipated manner--when he withdraws the machine from the workpiece and the tool, which is possibly stuck in the workpiece, remains in the latter. Since this separation of machine and tool is entirely unanticipated by the operator, there is the danger that he will lose his balance when working on a ladder or scaffold, which brings about a considerable risk of accident.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a tool of the above-described percussive and rotative type which is safer to operate than that currently available.
In keeping with this object and with others which will become apparent hereinafter, one feature of the present invention is that the rotary drivers of the tool receptacle assigned to the rotary driving grooves in the tool shaft are distributed around the circumference of the receptacle bore hole in such a way that two rotary drivers are never located diametrically opposite each other. The device according to the invention has the advantage that the tool can never be inserted in the tool holder in a position in which the locking elements arranged in the tool receptacle can engage in the rotary driving grooves opening out at the end of the tool shaft; this can be achieved without the necessity of applying additional locking means or the like.
It is particularly advantageous that a plurality of rotary driving grooves be arranged between the recesses which are closed on both sides, since the specific surface loading during the transmission of the driving torque is reduced as the number of rotary driving grooves increases, and the wear is accordingly decreased.
If one of the rotary driving grooves in the tool shaft is constructed so as to be deeper than the other rotary driving grooves and the respective strip-shaped rotary driver of the tool receptacle is constructed so as to be correspondingly higher, another advantageous step consists in providing a conical inserting bevel at the inserting end of the tool shaft, which inserting bevel encloses an angle .alpha. with the tool axis, and in providing the front sides of the strip-shaped rotary drivers at the tool side with inserting bevels which enclose an angle .beta. with the axis of the tool receptacle which is greater than the angle .alpha.. If, in addition to this, the conical inserting bevel is dimensioned in such a way that it cuts into the bases of the shallower rotary driving grooves, while leaving the base of the deeper rotary driving groove untouched, this arrangement provides the advantage that when
REFERENCES:
patent: 4107949 (1978-08-01), Wanner et al.
patent: 4335295 (1982-06-01), Fowler
patent: 4943192 (1990-07-01), Lafforgue et al.
Bishop Steven C.
Robert & Bosch GmbH
Striker Michael J.
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