Abnormality detecting device having function for detecting abnormality of machine tool, and abnormality detecting method

Patent metadata

Field	Value
Publication number	US-10024758-B2
Application number	US-201615135495-A
Country	US
Kind code	B2
Filing date	Apr 21, 2016
Priority date	May 19, 2015
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

An abnormality detecting device and method for detecting a symptom of a failure of a spindle of a machine tool before the spindle malfunctions. The abnormality detecting device for detecting an abnormality or malfunction includes a spindle motor and a motor controller. The motor controller includes a time measuring part which measures a spindle stopping time from when a free-run of the spindle motor accelerated to a predetermined number of rotations is started to when the spindle motor is stopped, a storing part which stores the spindle stopping time measured by the time measuring part, and a comparing part which compares a plurality of data with respect to the spindle stopping time stored in the storing part, and judges as to whether or not an abnormality exists in the spindle or the spindle motor.

First claim

The invention claimed is:

1. An abnormality detecting device comprising:
a spindle motor for driving a spindle of a machine tool; and
a motor controller for controlling the spindle motor,
wherein the motor controller comprises:
a time measuring part which measures a spindle stopping time from when the spindle motor is accelerated to a predetermined number of rotations to when the spindle motor is stopped after free-run of the spindle motor;
a storing part which stores the spindle stopping time measured by the time measuring part; and
a comparing part which compares a plurality of data with respect to the spindle stopping time stored in the storing part, the plurality of data including data when the spindle is normal, and judges as to whether an abnormality of the spindle or the spindle motor exists or not based on a comparison result.

2. The abnormality detecting device as set forth in claim 1 , further comprising at least one of: a spindle temperature sensor which detects a temperature of the spindle; and a motor temperature sensor which detects a temperature of the spindle motor,
wherein the comparing part judges as to whether an abnormality of the spindle or the spindle motor exists or not based on data of the spindle stopping time stored in the storing part, and the temperature of the spindle detected by the spindle temperature sensor or the temperature of the spindle motor detected by the motor temperature sensor.

3. The abnormality detecting device as set forth in claim 1 , further comprising at least one of: a spindle velocity sensor which detects a velocity of the spindle; and a motor velocity sensor which detects a velocity of the spindle motor,
wherein the comparing part judges as to whether an abnormality of the spindle or the spindle motor exists or not based on data of the spindle stopping time stored in the storing part, and the velocity of the spindle detected by the spindle velocity sensor or the velocity of the spindle motor detected by the motor velocity sensor.

4. The abnormality detecting device as set forth in claim 1 , wherein the comparing part judges that an abnormality of the spindle or the spindle motor exists when the spindle stopping time is below a predetermined threshold.

5. The abnormality detecting device as set forth in claim 1 , wherein the comparing part judges that an abnormality of the spindle or the spindle motor exists when a change rate of the spindle stopping time periodically measured is out of a range of a predetermined stopping time.

6. The abnormality detecting device as set forth in claim 2 , wherein the comparing part judges that an abnormality of the spindle or the spindle motor exists when the spindle stopping time is below a predetermined time, under constant temperature.

7. The abnormality detecting device as set forth in claim 2 , wherein the comparing part judges that an abnormality of the spindle or the spindle motor exists when the spindle stopping time at a first state, in which the temperature of the spindle or the spindle motor is a first value, is shorter than the spindle stopping time at a second state, in which the temperature of the spindle or the spindle motor is a second value lower than the first value.

8. The abnormality detecting device as set forth in claim 2 , wherein the comparing part judges that an abnormality of the spindle or the spindle motor exists when a change rate of the spindle stopping time periodically measured is out of a range of a predetermined stopping time, under constant temperature.

9. The abnormality detecting device as set forth in claim 3 , wherein the comparing part judges that an abnormality of the spindle or the spindle motor exists when a deceleration rate of the spindle or the spindle motor at the free-run exceeds a predetermined threshold.

Assignees

• Fanuc Corp

Inventors

• Kamiya Yohei

Classifications

• G01M13/00 Primary

  Testing of machine parts · CPC title

• G01M13/04

  Bearings · CPC title

• G01M15/00

  Testing of engines · CPC title

• B23Q17/008

  Life management for parts of the machine (tool life management B23Q17/0995) · CPC title

• B23Q1/70

  Stationary or movable members for carrying working-spindles for attachment of tools or work {(B23Q1/01 takes precedence; designed to be moved by using particular mechanisms B23Q1/44)} · CPC title