BLADE EDGE POSITION MATCHING METHOD FOR FORMER-USED TOOL AND LATER-USED TOOL OF MACHINE TOOL

PROBLEM TO BE SOLVED: To prevent the generation of step at a part of a work, on which blade tips of a former-used tool and a later-used tool abut, in the case of continuing the working with the later-used tool on the way of the working with the former-used tool. SOLUTION: A blade tip of a former-used tool is positioned at a position A as a reference of ON of a first detecting unit before or after the working operation with the former-used tool, and a before-working error and an after-working error as a difference between the theoretical position of the former-used tool and the real position thereof before the working is obtained. After installing a later-used tool in a spindle a blade tip of the later-used tool is positioned at the position A, in which the first detecting unit is turned on, and a difference between the theoretical position and the real position of the later-used tool is obtained as a before-working error of the later-used tool. When positioning the later-used tool at a working finish part of the work by the former-used tool, a target position programmed with the relative movement of a work table and the spindle is corrected on the basis of the before- working error and the after-working error of the former-used tool and the before- working error of the later-used tool.