Applicant: NSK LTD

Inventor: IGARASHI KIYOSHI

Priority: JP20120240925

International Classification: B23G1/36; B23G1/44; B24B41/04; B24B49/10

Application Number: WOJP2013/078993

Literature cited: JP2002326144A;JPS6119567A;JPS479093U

In this thread grinder, in which the axis of rotation (T) of a grinding-wheel shaft (51) is angled with respect to the axis (S) of a main shaft (1) and a thread groove is ground into an inside surface of a workpiece, a centering master (3) that has a cylindrical outside surface (3A) is mounted to the main shaft (1). A measuring unit (10) is mounted to said centering master (3), said measuring unit (10) being provided with two measuring instruments (20A, 20B) such that probes (22) can be placed up against two edges of a grinding wheel (52), at the top and bottom thereof. Said probes (22) are placed up against the cylindrical outside surface of the centering master (3) in order to set the origin for each of the measuring instruments (20A, 20B). The measuring unit (10) is moved in the axial direction of the centering master (3) so as to place the probes (22) of the two measuring instruments (20A, 20B) up against the top and bottom edges of the grinding wheel (52), respectively. The position of the grinding-wheel shaft (51) is then adjusted so as to make the measured value obtained by one measuring instrument (20A) and the measured value obtained by the other measuring instrument (20B) equal.