Patent ID: 7435158

Claim:
An initial position setting method of grinding wheels, before starting a grinding operation, in a vertical type of double disc surface grinding machine for a work-piece in which a pair of vertically opposing upper and lower grinding wheels are rotatably driven by grinding wheel rotation drive motors and vertically driven by grinding wheel vertical drive motors respectively so as to carry out the surface grinding simultaneously on the upper and lower ground surfaces of the work-piece; the method comprising: a first vertical moving stroke in which the grinding wheels are rotatably driven by grinding wheel rotation drive motors and are vertically driven by grinding wheel vertical drive motors so that the grinding wheels move toward the ground surfaces of the work-piece from setting-start positions which are vertically separated away from the ground surfaces of the work-piece, a first detection stroke in which a contact between a first grinding wheel and a first ground surface of the work-piece is detected, and the grinding wheels are stopped in the vertical direction on the basis of the detection, a first initial position setting stroke in which the first grinding wheel is vertically moved by a predetermined amount so that the first grinding wheel moves away from the first ground surface of the work-piece, while the second grinding wheel remains at stopped position in the vertical direction, a second vertical moving stroke in which the second grinding wheel is moved by the grinding wheel vertical drive motor so that the second grinding wheel further moves toward the second ground surface of the work-piece, a second detection stroke in which a contact between the second grinding wheel and the second ground surface of the work-piece is detected, and the second grinding wheel is stopped in the vertical direction on the basis of the detection and, a second initial position setting stroke in which the second grinding wheel is vertically moved by a predetermined amount so that the second grinding wheel moves away from the second ground surface of the work-piece.