Guide bush units for machine tools have heretofore been known in which a guide bush with a predetermined adjusted inner diameter dimension guides a bar material inserted in the guide bush.
One of what are known as guide bush adjusting devices configured to adjust the inner diameter dimension of the guide bush includes: a guide bush sleeve configured to house the guide bush; a guide bush adjusting nut provided to be displaceable with respect to the guide bush sleeve; and a fixing device to fix the guide bush adjusting nut to the guide bush sleeve (see Patent Literature 1, for example).
The guide bush adjusting device is configured to adjust the inner diameter dimension of the guide bush by: connecting the guide bush adjusting nut and the guide bush together; releasing the guide bush adjusting nut from its fixation, displacing the guide bush adjusting nut in a rotational direction by rotating the guide bush adjusting nut, and fixing the guide bush adjusting nut at a predetermined rotational position; and moving the guide bush with respect to the guide bush sleeve, and positioning the guide bush.
Patent Literature 1: Japanese Utility Model Registration Application Publication No. Sho 61-99404 (Claim of Utility Model Registration, and FIGS. 1 to 4)