Correction value measurement method and correction value measurement system of position measurement sensor in machine tool

A correction value measurement system for a position measurement sensor in a machine tool for measuring a length direction correction value and a radial direction correction value of the position measurement sensor in the machine tool, the machine tool including translational axes of three or more axes, a main spindle rotatable with a tool mounted thereon, a table, the position measurement sensor mountable to the main spindle, and a control device that controls the translational axes and the main spindle, the correction value measurement system comprising:

• a reference tool serving as a reference for a length of the tool;
• a tool sensor configured to detect a distal end position of the reference tool mounted to the main spindle;
• a reference sphere installed on a side of the tool sensor;
• and
• the control device, which includes:
• a tool sensor position acquisition unit configured to use the reference tool mounted to the main spindle and the tool sensor, and acquire and store a sensing position of a distal end of the reference tool;
• a reference tool measurement position acquisition unit configured to acquire a given tool measurement position using the reference tool mounted to the main spindle and store the given tool measurement position;
• a position measurement sensor measurement position acquisition unit configured to acquire a given sensor measurement position using the position measurement sensor mounted to the main spindle and store the given sensor measurement position;
• a position measurement sensor length calculation unit configured to obtain a difference between the tool measurement position and the sensor measurement position, calculate a length of the position measurement sensor based on the difference and a length of the reference tool, and store the length of the position measurement sensor;
• a reference sphere position acquisition unit configured to measure a position of the reference sphere using the position measurement sensor mounted to the main spindle and store the position of the reference sphere;
• a relative position calculation unit configured to calculate a relative position of the reference sphere with respect to the sensing position from the sensing position acquired by the tool sensor position acquisition unit, the position of the reference sphere acquired by the reference sphere position acquisition unit, the length of the position measurement sensor calculated by the position measurement sensor length calculation unit, and the length of the reference tool, and store the relative position;
• a reference tool position acquisition unit configured to acquire a reference tool position as the distal end position of the reference tool using the reference tool mounted to the main spindle and the tool sensor, and store the reference tool position;
• a length correction value calculation unit configured to calculate a length direction correction value of the position measurement sensor from the reference tool position acquired by the reference tool position acquisition unit, the position of the reference sphere acquired by the reference sphere position acquisition unit, the relative position calculated by the relative position calculation unit, and the length of the reference tool, and store the length direction correction value;
• and
• a diameter correction value calculation unit configured to measure the position of the reference sphere using the position measurement sensor mounted to the main spindle to calculate a radial direction correction value of the position measurement sensor using the measured position of the reference sphere and a preliminarily stored diameter dimension of the reference sphere, and store the radial direction correction value.