Expanded – threaded – driven – headed – tool-deformed – or locked-thr – Internally threaded fastener element – e.g. – nut – etc. – Multipart
Patent
1989-07-24
1990-07-17
Wilson, Neill R.
Expanded, threaded, driven, headed, tool-deformed, or locked-thr
Internally threaded fastener element, e.g., nut, etc.
Multipart
411535, 403259, 403261, F16B 3708, B24B 4500, B27B 532
Patent
active
049417908
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a clamp device for axially clamping a tool, particularly a disc, and which comprises a clamp nut and a clamp located between the disc and the clamp nut and connected with the clamp nut with a possibility of an axial movement relative thereto. Clamp devices of this kind are mainly suitable for portable hand machine tools and in this connection particularly grinding machines. A clamp device of the kind mentioned is known (German Patent Specification No. 3,012,836), in which the clamp disc consists of a member which has an approximately hat-shaped cross-section and which is supported axially against the flange of the clamp nut by a coil spring. When the clamp nut is screwed on and tightened, this clamp disc is pressed axially against the tool by the axially compressed spring and thus the tool is tightened against the flange on the spindle side, while the, end face of a cylindrical extension of the clamp nut abuts directly against a facing axial side of the flange on the spindle side and, when the clamp nut is further tightened the flange on the spindle side is tightened, together with the clamp nut, possibly until the rear flange abuts axially against the spindle shoulder surface forming the supporting member. It is thereby intended, in the case of an angle grinder, to enable the grinding wheel to be clamped with a predetermined contact pressure and to ensure that this contact pressure is maintained. This clamp device is also intended to allow rapid and, simple changing of the grinding wheel and at the same time, to avoid overloading of the hand machine tool, particularly of the angle grinder. If in fact the torque acting on the grinding wheel is too high, the grinding wheel stops whereas the rear flange and the clamp nut together with the clamp disc make a relative movement in relation to it. This clamp device counteracts the effect of the further spontaneous tightening of the clamp nut during operation, which would otherwise make it considerably more difficult to loosen the clamp nut for the purpose of changing the grinding wheel. Nevertheless, the clamp nut can here be unscrewed only with aid of a special auxiliary tool, while, depending on the construction of the machine, the spindle has to be securely held correspondingly fast with a second auxiliary tool, for example a spanner.
SUMMARY OF THE INVENTION
The object of the invention is to provide a clamp device which makes possible to change the tool without any auxiliary tool, while in addition this tool change can be made quickly and reliably. The object of the invention is achieved by providing a clamp device of the type mentioned above in which the clamp disc and/or the clamp nut is (are) provided with stops for respective rolling members guided on tracks of an operating member disposed between the clamp nut and clamp disc, and the operating member is spring-loaded in a direction which is opposite to the nut release direction. Another advantage of the clamp device according to the invention is that even existing hand machine tools can be converted without any particular reconstruction. For this purpose, it is for example sufficient simply to replace the existing conventional clamp nut with the complete unit consisting of a clamp nut with clamp disc and operating member. In the externally accessible region the clamp nut can still in all respects be of conventional construction, for example in conformity with standards, so that in particularly obstinate cases, for example when the clamp nut has severely rusted, a spanner can still be applied and the clamp nut released with this auxiliary tool. The same principle in accordance with the clamp device according to the invention can also be put into practice for the rear flange on the spindle side, in which case this flange is then replaced with the complete unit consisting of a clamp nut with clamp disc and operating member, the clamp disc then is pressed at the rear against the tool.
It may be sufficient for the supporting members to have correspondin
REFERENCES:
patent: 2290215 (1942-07-01), Stenberg
patent: 4525097 (1985-06-01), Ziegelmeyer
Robert & Bosch GmbH
Striker Michael J.
Wilson Neill R.
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