Chucks or sockets – Expanding – Fluid-pressure actuator
Reexamination Certificate
1999-04-27
2001-01-09
Bishop, Steven C. (Department: 3722)
Chucks or sockets
Expanding
Fluid-pressure actuator
C279S004020, C279S004110, C279S121000, C279S126000, C279S132000, C279S127000
Reexamination Certificate
active
06170835
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a workpiece clamping apparatus.
It will be noted at this point that the term workpiece clamping apparatus embraces both an apparatus with a mechanism adapted to clamp a workpiece on the exterior thereof, which can be referred to as an external workpiece apparatus, such as a chuck, and also an apparatus with a mechanism adapted to clamp a workpiece on the interior thereof, which can be referred to as an internal workpiece clamping apparatus.
BACKGROUND OF THE INVENTION
One form of workpiece clamping apparatus comprises a housing having inclined guides which, as viewed in radial planes thereof, extend inclinedly with respect to the axial direction. A plurality of clamping motion elements are displaceable along the guides and carry clamping jaws for clamping a workpiece to be clamped by the apparatus. A plurality of clamping pistons are associated with respective ones of the clamping motion elements, to provide for clamping the workpiece. The apparatus further includes a displacement actuation assembly which permits the clamping motion elements to be moved into respective released positions and clamping readiness positions in which the clamping motion elements are in a ready position to initiate clamping of the workpiece. An apparatus of that kind is to be found for example in DE-A 41 14 884.
That apparatus has a control member in the form of an actuation disk with the clamping pistons carried thereon, in order to draw respective projections of the clamping motion elements or like clamping bodies against the abutment surface of the actuation disk, thereby to permit displacement of the clamping motion elements. In that way the apparatus closes and the clamping jaws are caused to bear uniformly against the workpiece. The application of clamping pressure to the clamping pistons causes the workpiece which has been previously uniformly embraced to be clamped fast. While that apparatus operates satisfactorily and with a reasonable degree of precision, there are clamping reaction forces which make themselves noticeable at the actuation disk.
Another workpiece clamping apparatus as disclosed in EP 0 800 884 A2 involves the co-operation of motion-producing taper members which are guided in the axial direction and clamping jaws which are guided in radial directions, in order to bear gently against the workpiece before clamping pistons which are actuated by way of a presetting bar definitively clamp the workpiece fast.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a workpiece clamping apparatus so designed as to afford a reduction in reaction forces arising out of a workpiece-clamping procedure.
Another object of the present invention is to provide a workpiece clamping apparatus which provides for an improved workpiece-clamping procedure in terms of precision and delicacy of operation while affording a firm clamping action and enjoying simplicity of structure.
Still another object of the present invention is to provide a workpiece clamping apparatus which is so designed that components can perform a respective plurality of functions.
In accordance with the principles of the present invention the foregoing and other objects are achieved by a workpiece clamping apparatus comprising a housing having inclined guides which, as viewed in radial planes, extend inclinedly with respect to the axial direction of the housing. A plurality of clamping motion elements are displaceable along the inclined guides and carry clamping jaws for clamping a workpiece. A plurality of clamping pistons are each associated with a respective one of the motion clamping elements to cause clamping of the workpiece. A displacement actuation means permits the clamping motion elements to be moved into respective released positions and clamping readiness positions. The clamping pistons are mounted in cylinder chambers which are fixed with respect to the housing and can be acted upon by way of fluid feed ducts which extend in part by way of the displacement actuation means. The fluid feed ducts permit control fluid to be fed to the cylinder chambers selectively either without pressure or with a take-up pressure or with a clamping pressure.
As will become readily apparent from a description hereinafter of preferred embodiments of the workpiece clamping apparatus according to the invention, the displacement actuation means is thus primarily a control fluid feed member.
In addition however the displacement actuation means also involves the function of acting as an abutment for projections on the clamping motion elements which can be displaced controlledly in that way, more specifically into their initial or starting position, in which case the necessary displacement force is applied by way of the displacement actuation means, or into the clamping readiness position, in which case the necessary displacement force is applied by actuation of the clamping pistons.
Further objects, features and advantages of the invention will be apparent from the following description of preferred embodiments.
REFERENCES:
patent: 5102152 (1992-04-01), Grund et al.
patent: 41 14 884 A1 (1992-11-01), None
Bishop Steven C.
Reising Ethington, Barnes, Kisselle, Learman & McCulloch, P.C.
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