MOTOR CONTROLLER DETECTING ABNORMALITY OF POWER TRANSMISSION UNIT BETWEEN MAIN SPINDLE AND MOTOR

• US 20150115855A1
• Filed: 10/27/2014
• Published: 04/30/2015
• Est. Priority Date: 10/30/2013
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Naitou, Genzou
• Granted Patent: US 10,018,677 B2
• Time in Patent Office: Days
• US Class Current: 318/467
• CPC Class Codes: G01R 31/343 in operation
• CPC Class Codes: H02K 11/21 Devices for sensing speed or position, or actuated thereby specially adapted for machines having non-mechanical commutating devices H02K29/06, H02K29/14
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage

Abstract

A motor controller includes a single-rotation signal detector detecting a single-rotation signal that indicates a single rotation of a main spindle, a rotation angle detector detecting a rotation angle of a motor every predetermined time, and a counter adding up the rotation angle. A value of the counter is reset when the single-rotation signal detector detects the single-rotation signal of the main spindle. The motor controller further includes a judgment unit judging that a power transmission unit has abnormality when a value of the rotation angle of the motor added up in the counter deviates from a predetermined range.

Claims

1. A motor controller detecting an abnormality in a power transmission unit that connects a motor and a main spindle of a machine tool and has a known speed reduction ratio, the motor controller comprising:

a single-rotation signal detector detecting a single-rotation signal that indicates a single rotation of the main spindle;

a rotation angle detector detecting a rotation angle of the motor every predetermined time;

a counter adding up the rotation angle detected by the rotation angle detector every predetermined time, a value of the counter being reset when the single-rotation signal detector detects the single-rotation signal of the main spindle; and

a judgment unit judging that the power transmission unit has an abnormality when a value of the rotation angle of the motor added up in the counter deviates from a predetermined range.

2. The motor controller according to claim 1, wherein a mechanism is provided that changes the speed reduction ratio of the power transmission unit, and when the mechanism changes the speed reduction ratio of the power transmission unit, the predetermined range is changed according to the change of the speed reduction ratio.

3. The motor controller according to claim 1, wherein the predetermined range is set as an upper limit value of the rotation angle of the motor, and

when the added-up value of the rotation angle of the motor exceeds the upper limit value, the judgment unit judges that the power transmission unit has an abnormality.

4. The motor controller according to claim 2, wherein the predetermined range is set as an upper limit value of the rotation angle of the motor, and

when the added-up value of the rotation angle of the motor exceeds the upper limit value, the judgment unit judges that the power transmission unit has an abnormality.

5. The motor controller according to claim 1, wherein the predetermined range is set as a range between an upper limit value and a lower limit value of the rotation angle of the motor,

when the added-up value of the rotation angle of the motor exceeds the upper limit value during acceleration or constant-speed driving of the motor, the judgment unit judges that the power transmission unit has an abnormality, and when the value of the rotation angle of the motor added up in the counter at the time of detection of the single-rotation signal of the main spindle falls down the lower limit value during deceleration or stop of the motor, the judgment unit judges that the power transmission unit has an abnormality.

6. The motor controller according to claim 2, wherein the predetermined range is set as a range between an upper limit value and a lower limit value of the rotation angle of the motor,

when the added-up value of the rotation angle of the motor exceeds the upper limit value during acceleration or constant-speed driving of the motor, the judgment unit judges that the power transmission unit has an abnormality, and when the value of the rotation angle of the motor added up in the counter at the time of detection of the single-rotation signal of the main spindle falls to the lower limit value during deceleration or stop of the motor, the judgment unit judges that the power transmission unit has an abnormality.

7. The motor controller according to claim 1, wherein the power transmission unit includes a belt and pulleys for winding the belt therearound.

8. The motor controller according to claim 2, wherein the power transmission unit includes a belt and pulleys for winding the belt therearound.

9. The motor controller according to claim 1, further comprising an alarm unit generating an alarm when the judgment unit judges that the power transmission unit has an abnormality.

10. The motor controller according to claim 2, further comprising an alarm unit generating an alarm when the judgment unit judges that the power transmission unit has an abnormality.

11. The motor controller according to claim 9, wherein, a zero speed command is further given to the motor to stop the motor when the judgment unit judges that the power transmission unit has an abnormality.

12. The motor controller according to claim 10, wherein, a zero speed command is further given to the motor to stop the motor when the judgment unit judges that the power transmission unit has an abnormality.

13. The motor controller according to claim 9, wherein, excitation of the motor is interrupted when the judgment unit judges that the power transmission unit has an abnormality.

14. The motor controller according to claim 10, wherein, excitation of the motor is interrupted when the judgment unit judges that the power transmission unit has an abnormality.