Method for correcting a position of a tip of a machine tool

A method for correcting a position of a tip of a machine tool, wherein the machine tool comprises:

• a mounting table on which a workpiece is placed;
• a tool configured to machine the workpiece placed on the mounting table, the tool including the tip;
• a shade detector fixed on the mounting table and configured to provide an optical path of a laser light and detect a shade state of the laser light;
• and
• a tool controller connected to the mounting table via a pair of columns and configured to control an orientation and a position of the tool,
• wherein a reference point associated with the tool is provided to the tool controller, and the method for correcting comprises:
• a matching process in which the tool controller actually matches the tip of the tool with a measurement position of the laser light, while keeping a first orientation which is an orientation of the tool for machining, the matching being based on the first orientation and a length of the tool, the matching process comprising:
• a first moving process in which the tool controller moves the tool in one axial direction while keeping the first orientation;
• and
• a specifying process in which the tool controller specifies, in the first moving process:
• a first reference point position that is a position of the reference point in a state in which the measurement position of the laser light is shaded in a first portion of the tool, and
• the second reference point position that is a position of the reference point in a state in which the measurement position of the laser light is shaded in a second portion of the tool when the tool is moved in said axial direction;
• and
• a first tool position specifying process in which the first tool position, which is a position of the reference point in a state in which the tip is actually matched with the measurement position of the laser light, is specified, the first tool position specifying process comprising:
• a first process wherein the tool controller controls positioning of the tool such that the reference point is positioned on a straight line connecting the measurement position of the laser light and a central point of a line defined by the first reference point position and the second reference point position, while keeping the first orientation of the tool and moving the tool such that the reference point is positioned along the straight line while keeping the first orientation of the tool;
• and
• a second process wherein the tool controller specifies a third reference point position that is the position of the reference point in a state in which the measurement position is shaded by the tip when the tool is moved along the straight line.