Hammer drill

Details Hammer drill Hammer drill

1993-11-08

1994-12-20

Smith, Scott A.

Tool driving or impacting

Impacting devices

With means for rotating tool

173122, B25D 1104

Patent

active

053739051

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a hammer drill.
More particularly, it relates to a motor-driven hammer drill which has a casing and a multi-part hammering sleeve with a guide tube and a tool socket driven in rotation by a motor.
DE 38 28 309 C2 discloses a hammer drill in which, contrary to the customary design, the guide tube for the striking mechanism and the tool socket is in two parts. The two parts are connected by locking elements which, in the form of balls, engage in recesses in both parts, this entailing high point loading of the parts. For this reason, it was necessary to heat-treat or harden both the guide tube and the tool socket. Moreover, the construction requires a high constructional outlay.


SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a hammer drill which avoids the disadvantages of the prior art.
In keeping with these objects and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a motor-driven hammer in which the tool socket is attached to the hammering sleeve by means of an axial connection which has a resilient slotted profiled ring which, in its assembled position, can be inserted completely under radial prestress into an annular assembly groove, and with the hammering sleeve fully assembled engages in an annular groove of the component to be connected, and the annular assembly groove has a bearing surface set obliquely to a normal to the longitudinal axis of the tool socket against which bearing surface the profiled ring rests with the hammering sleeve fully assembled.
When the motor-driven hammer is designed in accordance with the present invention, it has the advantage that the high axial forces deriving from the striking mechanism are transmitted over a larger area. This makes possible the use of an unhardened guide tube, hardening distortion and finishing work on the guide tube thereby being avoided. Not least, the lower weight of the components to be hardened is also accompanied by a significant reduction of the burden on the environment by the elimination of hardening steps.
The use of a resilient profiled ring and corresponding grooves, preferably of matching shape, in the guide tube and in the tool socket avoid shear stresses on the connecting element, with the result that the profiled ring is only subjected to compressive stress and the pressures which occur between "hard" and "soft" components are not in the form of point loads but only of loads distributed over a surface. By running-in during operation, at the very latest, the grooves adapt precisely to the shape of the profiled rings, with the result that they bear the loads with their entire surface. The axial connection according to the invention has the further advantage that the hammering sleeve is easy to produce by plug-in assembly and that satisfactory truth of running of the tool holder is guaranteed.
Advantageous further developments and improvements of the hammer drill are possible. In its oblique position relative to the longitudinal axis, the bearing surface can be flat or, alternatively, have a concave curvature in order to adapt to the outer contour of the profiled ring used. The profiled ring can, in particular, have a circular or oval, rectangular or some other cross-section.
It is particularly advantageous to transmit the torque required at the tool socket via a press fit since only limited forces can be transmitted in the circumferential direction via the profiled ring. Also advantageous is a latching ring as a coupling part for a safety clutch, the ring being secured by means of a plurality of rollers which rest in linear fashion in recesses, of which there are preferably three. This makes the latching ring easy to exchange in the event of wear. While providing the possibility of easy manufacture, the rollers make it possible to transmit the torque well between the latching ring and the guide sleeve. To provide axial securing, a round ring can preferably be addi

REFERENCES:
patent: 3828863 (1974-08-01), Bleicher et al.
patent: 3874460 (1975-04-01), Schmid et al.
patent: 4719976 (1988-01-01), Bleicher et al.
patent: 4750567 (1988-06-01), Grossmann et al.

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