METHOD AND APPARATUS FOR POSITIONING CUTTING TOOL, AND ELECTRICAL DEVICE FOR TOOL POSITIONING

摘要

A positioning device (10) for positioning the point of a cutting tool with respect to the axis of a workpiece bar comprises a spherical material (16) with an electrically conducting surface area (16a); an abutment mechanism (22) that brings the spherical material (16) into contact with the inner edge (20a) of an opening (20) in an end of a holder (18) for holding a workpiece bar to hold a part of it coaxially in the opening (20); a drive mechanism (32) for bringing the cutting tool (28) into contact with the electrically conducting surface area of a spherical material; an electrical unit (24) for supplying current between the cutting tool and the conducting surface area of the spherical material when they are in contact; a detector (34) for detecting a conducting state between the cutting tool and the conducting surface area of the spherical material by means of the electrical unit to determine the contact position of the cutting tool; and a processor (36) that determines the position of the center (16c) of the spherical material based on the contact position of the cutting tool and corrects predetermined tool position data properly depending on the determined center position.