Method for centering grinding wheel in thread grinder and measurement device for centering

A method for centering a grinding wheel in a thread grinder which includes:

• a grinding wheel shaft;
• a grinding wheel attached to the grinding wheel shaft;
• and a main shaft which faces the grinding wheel shaft and to which a workpiece having a cylindrical inner surface to be ground with a thread groove is attached, wherein a rotation axis of the grinding wheel shaft is inclined with respect to an axis of the main shaft in accordance with a lead angle of the thread groove, the method comprising:
• mounting a centering master having a cylindrical outer surface to the main shaft such that a center axis of the centering master is matched with the axis of the main shaft;
• mounting a measuring unit to the centering master to be movable in an axis direction of the centering master, the measuring unit including:
• a first measuring instrument having a first probe configured to contact one edge part of the grinding wheel in an orthogonal direction orthogonal to the axis direction of the centering master;
• and a second measuring instrument having a second probe configured to contact another edge part of the grinding wheel opposite to the one edge part in the orthogonal direction;
• setting origins of the first and second measuring instruments by bringing the first and second probes into contact with the cylindrical outer surface of the centering master;
• moving the measuring unit in the axis direction of the centering master to thereby bring the first and second probes into contact with the respective edge parts of the grinding wheel in the orthogonal direction;
• and
• centering a center of the grinding wheel with respect to the axis of the main shaft by adjusting a position of the grinding wheel shaft such that a measured value obtained based on the origin of the first measuring instrument and a measured value obtained based on the origin of the second measuring instrument become same.