Correction Method at Time of Feed Axis Reversal

• US 20130173046A1
• Filed: 10/26/2011
• Published: 07/04/2013
• Est. Priority Date: 10/27/2010
• Status: Active Grant

• Current Assignee: Makino Milling Machine Company Limited
• Original Assignee: Makino Milling Machine Company Limited
• Inventors: Kawana, Akira, Mori, Norio, Oda, Mitsunari
• Granted Patent: US 9,588,509 B2
• Time in Patent Office: Days
• US Class Current: 700/186
• CPC Class Codes: G05B 19/182 characterised by the machine tool function, e.g. thread cutting, cam making, tool direction control G05B19/21 - G05B19/40 take precedence
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/41078 Backlash acceleration compensation when inversing, reversing direction
• CPC Class Codes: G05B 2219/41084 Compensation speed axis with changing, reversing direction, quadrant circle
• CPC Class Codes: G05B 2219/41115 Compensation periodical disturbance, like chatter, non-circular workpiece

Abstract

A stick motion correction method which corrects stick motion which occurs at time of reversal of a feed axis of a numerical control machine tool stores a position command to be commanded to a servo motor from an NC program of a numerical control machine tool for each predetermined control period from a current position command to a later position command, calculates a reversal correction command based on the stored position commands, calculates an advancement time for advancing timing of addition of the reversal correction command to a speed or torque command of the motor from reversal timing of the servo motor, based on information obtained from operation of the motor and adds the reversal correction command to the speed or torque command of the servo motor to precisely correct stick motion at a timing advanced from the reversal timing of the servo motor by an exact time.

Claims

1. A stick motion correction method which corrects stick motion which occurs at the time of reversal of a movement direction of a feed axis of a numerical control machine tool, which stick motion correction method comprising steps of:

storing a position command to be commanded to a servo motor from an NC program of said numerical control machine tool for each predetermined control period from a current position command to a position command after a predetermined time;

calculating a reversal correction command based on the stored position commands;

calculating an advancement time for advancing a timing of addition of said reversal correction command to a speed command or torque command of said servo motor from the reversal timing of said servo motor, based on information obtained from operation of said servo motor or commands to said servo motor; and

adding said reversal correction command to the speed command or torque command of said servo motor to correct stick motion at a timing advanced from the reversal timing of said servo motor by exactly said advancement time.

2. The stick motion correction method as set forth in claim 1, wherein the information obtained from operation of said servo motor or commands to said servo motor is acceleration which is found from a plurality of said position commands which are stored in said storage unit.

3. The stick motion correction method as set forth in claim 1, wherein the information obtained from operation of said servo motor is position error between said position commands and an actual position of said servo motor.

4. The stick motion correction method as set forth in claim 1, wherein further said advancement time is adjusted based on at least one of torque error between a torque command and actual torque of said servo motor and current error between a current command and actual current of said servo motor.

5. The stick motion correction method as set forth in claim 2, wherein further said advancement time is adjusted based on at least one of torque error between a torque command and actual torque of said servo motor and current error between a current command and actual current of said servo motor.

6. The stick motion correction method as set forth in claim 3, wherein further said advancement time is adjusted based on at least one of torque error between a torque command and actual torque of said servo motor and current error between a current command and actual current of said servo motor.