Abstract: A semiconductor strain sensor has a semiconductor substrate having a pair of major surfaces parallel to each other. The substrate is worked to constitute a frame and a thin diaphragm by forming a circular blind hole from one major surface. The bottom surface of the blind hole is formed in a conical shape projecting upward from the edge portion to a central portion thereof. The substrate has a thickness of not less than 0.5 mm and not less than about five times that of the diaphragm. The blind hole is formed by grinding and the inner surface of the blind hole is then etched to eliminate a scratch formed in the inner surface by grinding. Resistance layers are formed on the other major surface of the substrate. Each layer has a piezoresistance which varies in accordance with the pressure applied to the diaphragm.

Abstract: An apparatus for machining the periphery of a work is provided with a grinding wheel, a holding mechanism for holding the work, and a moving mechanism for moving the holding mechanism toward or away from the wheel. A touch sensor for detecting the contact between a grinding surface of the wheel and a test piece held by the holding mechanism is connected to the wheel and the holding mechanism. The forward or backward movement of the moving mechanism is numerically controlled by a sequence controller using a microcomputer. Data representing the position of the holding mechanism when the touch sensor detects the contact between the grinding surface of the wheel and the test piece is stored in an internal memory of the controller as machining end position data (N1). The memory also prestores machining amount data (N2) and total stroke data (N2+N3).