Working pressure control mechanism

Claim 1

A working pressure control mechanism for lapping, honing, and grinding machines having a rotatably mounted shaft bearing the tool within an axially translatable housing such that the shaft is carried along by the housing in the direction of the tool advance, comprising a spring means capable of axially translating the housing; a signal producing means capable of producing a signal corresponding to the magnitude of axial displacement caused by the workpiece and connected to said spring means; a mechanism advance control means capable of receiving a signal from said signal producing means, and advancing the housing to compensate for the degree of axial displacement; and wherein the shaft is rotatably mounted in a first bushing which is parallel to the axis of the shaft; said first bushing being disposed inside the housing, which housing is a hollow piston rod; said first bushing having at least one region, defined by thin wall rings, along its length which is elastically deformable by the force applied to it due to the advancing motion of the hollow piston rod, and which region contains mounted therein at least one strain gauge strip whose electrical resistance varies with changes in its length; said strip being connected to the input of an electrical comparator which controls the advancing force of the hollow piston rod and by it, through the shaft, the tool.