Error identification method of machine tool and error identification system of the same

An error identification system for measuring a position of a measured jig in a three-dimensional space and identifying a geometric error in a machine tool from a value of the measured position, in which the measured jig is secured on a table by a position measurement sensor installed to a main spindle in the machine tool, the machine tool including three or more translational axes, one or more rotation axes, the rotatable main spindle to which a tool is to be installed, the table, and a control device configured to control the respective translational axes, rotation axis, and main spindle, the error identification system comprising:

• a reference tool for a length reference of the tool;
• a tool sensor configured to detect a distal end position of the reference tool installed to the main spindle;
• a reference block installed to the tool sensor side;
• a tool sensor position acquisition unit configured to move the reference tool installed to the main spindle in the translational axes and acquire and store a sensing position of the distal end of the reference tool with the tool sensor;
• a reference block position acquisition unit configured to move the reference tool installed to the main spindle in the translational axes to directly or indirectly bring the reference tool into contact with the reference block, the reference block position acquisition unit being configured to acquire and store positions of the translational axes at the contact;
• a relative position calculation unit configured to calculate and store a relative position of the reference block with respect to the sensing position from the sensing position acquired in the tool sensor position acquisition unit and the positions of the translational axes acquired in the reference block position acquisition unit;
• a reference tool position acquisition unit configured to move the reference tool installed to the main spindle in the translational axes, the reference tool position acquisition unit being configured to acquire and store a reference tool position with the tool sensor, the reference tool position being the distal end position of the reference tool;
• a measurement position acquisition unit configured to measure and store a position of the reference block with the position measurement sensor installed to the main spindle;
• a length compensation value calculation unit configured to calculate and store a length direction compensation value of the position measurement sensor from the reference tool position acquired in the reference tool position acquisition unit, the position of the reference block acquired in the measurement position acquisition unit, the relative position acquired in the relative position calculation unit, and the length of the reference tool;
• a diameter compensation value acquisition unit configured to acquire and store a radial direction compensation value of the position measurement sensor with the measured jig;
• a position compensation unit configured to index the rotation axis to a plurality of any given angles and compensate and store the respective values of the measured position of the measured jig measured by the position measurement sensor using the length direction compensation value and the radial direction compensation value;
• and
• a geometric error identification unit configured to identify the geometric error from the plurality of the values of the measured position compensated in the position compensation unit.

An error identification method for measuring a position of a measured jig in a three-dimensional space and identifying a geometric error in a machine tool from a value of the measured position, in which the measured jig is secured on a table by a position measurement sensor installed to a main spindle in the machine tool, the machine tool including three or more translational axes, one or more rotation axes, the rotatable main spindle to which a tool is to be installed, the table, and a control device configured to control the respective translational axes, rotation axis, and main spindle, the error identification method comprising:

• a tool sensor position acquisition stage of installing a reference tool for a length reference of the tool to the main spindle and acquiring a sensing position of a distal end of the reference tool with a tool sensor;
• a reference tool measurement position acquisition stage of acquiring any given tool measurement position with the reference tool installed to the main spindle;
• a position measurement sensor measurement position acquisition stage of acquiring any given sensor measurement position with the position measurement sensor installed to the main spindle;
• a position measurement sensor length calculation stage of acquiring a difference between the tool measurement position and the sensor measurement position and acquiring a length of the position measurement sensor based on the difference and the length of the reference tool;
• a first reference block position acquisition stage of measuring a position of a reference block disposed at the tool sensor side with the position measurement sensor installed to the main spindle;
• a relative position calculation stage of calculating a relative position of the reference block with respect to the sensing position from the sensing position acquired in the tool sensor position acquisition stage, the position of the reference block acquired in the first reference block position acquisition stage, the length of the position measurement sensor calculated in the position measurement sensor length calculation stage, and the length of the reference tool;
• a reference tool position acquisition stage of installing the reference tool to the main spindle and acquiring a reference tool position with the tool sensor, the reference tool position being a distal end position of the reference tool;
• a second reference block position acquisition stage of installing the position measurement sensor to the main spindle and measuring a position of the reference block with the position measurement sensor;
• a length compensation value calculation stage of calculating a length direction compensation value of the position measurement sensor from the reference tool position acquired in the reference tool position acquisition stage, the position of the reference block measured in the second reference block position acquisition stage, the relative position calculated in the relative position calculation stage, and the length of the reference tool;
• a diameter compensation value acquisition stage of acquiring a radial direction compensation value of the position measurement sensor with the measured jig;
• a position measurement stage of indexing the rotation axis to a plurality of any given angles and measuring respective positions of the measured jig by the position measurement sensor;
• a position compensation stage of compensating the values of the measured position at the position measurement stage using the length direction compensation value and the radial direction compensation value;
• and
• a geometric error identification stage of identifying the geometric error from the plurality of the values of the measured position compensated in the position compensation stage.

An error identification system for measuring a position of a measured jig in a three-dimensional space and identifying a geometric error in a machine tool from a value of the measured position, in which the measured jig is secured on a table by a position measurement sensor installed to a main spindle in the machine tool, the machine tool including three or more translational axes, one or more rotation axes, the rotatable main spindle to which a tool is to be installed, the table, and a control device configured to control the respective translational axes, rotation axis, and main spindle, the error identification system comprising:

• a reference tool for a length reference of the tool;
• a tool sensor configured to detect a distal end position of the reference tool installed to the main spindle;
• a reference block installed to the tool sensor side;
• a tool sensor position acquisition unit configured to move the reference tool installed to the main spindle in the translational axes and acquire and store a sensing position of the distal end of the reference tool with the tool sensor;
• a reference tool measurement position acquisition unit configured to acquire and store any given tool measurement position with the reference tool installed to the main spindle;
• a position measurement sensor measurement position acquisition unit configured to acquire and store any given sensor measurement position with the position measurement sensor installed to the main spindle;
• a position measurement sensor length calculation unit configured to acquire a difference between the tool measurement position and the sensor measurement position, the position measurement sensor length calculation unit being configured to calculate and store a length of the position measurement sensor based on the difference and the length of the reference tool;
• a first reference block position acquisition unit configured to measure and store a position of the reference block with the position measurement sensor installed to the main spindle;
• a relative position calculation unit configured to calculate and store a relative position of the reference block with respect to the sensing position from the sensing position acquired in the tool sensor position acquisition unit, the position of the reference block acquired in the first reference block position acquisition unit, the length of the position measurement sensor calculated in the position measurement sensor length calculation unit, and the length of the reference tool;
• a reference tool position acquisition unit configured to move the reference tool installed to the main spindle in the translational axes, the reference tool position acquisition unit being configured to acquire and store a reference tool position with the tool sensor, the reference tool position being the distal end position of the reference tool;
• a second reference block position acquisition unit configured to measure and store a position of the reference block with the position measurement sensor installed to the main spindle;
• a length compensation value calculation unit configured to calculate and store a length direction compensation value of the position measurement sensor from the reference tool position acquired in the reference tool position acquisition unit, the position of the reference block acquired in the second reference block position acquisition unit, the relative position calculated in the relative position calculation unit, and the length of the reference tool;
• a diameter compensation value acquisition unit configured to acquire and store a radial direction compensation value of the position measurement sensor with the measured jig;
• a position compensation unit configured to index the rotation axis to a plurality of any given angles and compensate and store the respective values of the measured position of the measured jig measured by the position measurement sensor using the length direction compensation value and the radial direction compensation value;
• and
• a geometric error identification unit configured to identify the geometric error from the plurality of the values of the measured position compensated in the position compensation unit.