Drive control system for motors
AssigneeFujitsu Fanuc Limited
InventorsYoshinori Kohzai, Yoshiki Fujioka
Life of this patent
Estimating the term…
Abstract
A motor drive control system for use in a machine tool having spindle and feed shaft motors. If the spindle motor, which is rotating at a constant speed during a machining operation, is subjected to an overload, and consequently experiences a drop in speed, this fact is detected by a detector for detecting the armature current of the spindle motor. The feed shaft motor is slowed down to a predetermined speed if the overloaded condition continues for a prescribed period of time. The feed shaft motor is stopped if an even greater armature current is detected to be flowing due to a continuing overload despite the fact that the feed shaft motor has been slowed to the predetermined speed.
Claims11
A system for controlling motor drive in a numerically controlled machine tool having speed command means for generating a speed command signal, a spindle motor, operatively connected to the speed command means, driven to rotate a tool in accordance with the speed command signal, a numerical control device for generating a feed command signal, and a feed shaft motor, operatively connected to the numerical control device, driven to transport a workpiece relative to the tool in accordance with the feed command signal, so that the tool may subject the workpiece to a predetermined machining operation, said system comprising:
- first detection means, operatively connected to the spindle motor, for detecting the armature current of the spindle motor;
- second detection means, operatively connected to said first detection means, for detecting when the armature current of the spindle motor has continuously exceeded a preset current value for a period of time greater than a predetermined time period;
- third detection means for detecting an acceleration or deceleration condition of the spindle motor in dependence upon the speed command signal;
- and
- means, operatively connected to said second and third detection means and the feed shaft motor, for slowing down the feed shaft motor when said second detection means detects that the armature current of the spindle motor has continuously exceeded the preset current value for a period of time greater than the predetermined time period under a condition in which the spindle motor is neither being accelerated nor decelerated, as detected by said third detection means.
A system for controlling motor drive in a numerically controlled machine tool having speed command means for generating a speed command signal, a spindle motor, operatively connected to the speed command means, driven to rotate a tool in accordance with the speed command signal, a numerical control device for generating a feed command signal, and a feed shaft motor, operatively connected to the numerical control device, driven to transport a workpiece relative to the tool in accordance with the feed command signal, so that the tool may subject the workpiece to a predetermined machining operation, said system comprising:
- first detection means, operatively connected to the spindle motor, for detecting the armature current of the spindle motor;
- second detection means, operatively connected to said first detection means, for detecting when the armature current of the spindle motor has continuously exceeded a preset current value for a period of time greater than a predetermined time period;
- third detection means for detecting an acceleration or deceleration condition of the spindle motor in dependence upon the speed command signal;
- and
- means, operatively connected to said second and third detection means and the feed shaft motor, for stopping the feed shaft motor when said second detection means detects that the armature current of the spindle motor has continuously exceeded the preset current value for a period of time greater than the predetermined time period under a condition in which the spindle motor is neither being accelerated nor decelerated, as detected by said third detection means.
A system for controlling motor drive in a numerically controlling machine tool having speed command means for generating a speed command signal, a spindle motor, operatively connected to the speed command means, driven to rotate a tool in accordance with the speed command signal, a numerical control device for generating a feed command signal, and a feed shaft motor, operatively connected to the numerical control device, driven to transport a workpiece relative to the tool in accordance with the feed command signal, so that the tool may subject the workpiece to a predetermined machining operation, said system comprising:
- first detection means, operatively connected to the spindle motor, for detecting the armature current of the spindle motor;
- second detection means, operatively connected to said first detection means, for detecting when the armature current of the spindle motor has continuously exceeded a first preset current value for a period of time greater than a first predetermined time period;
- third detection means, operatively connected to said first detection means, for detecting that the armature current of the spindle motor has continuously exceeded a second preset current value, which is greater than the first preset current value, for a period of time greater than the first predetermined time period;
- fourth detection means for detecting an acceleration or deceleration condition of the spindle motor in dependence upon the speed command signal;
- and
- means, operatively connected to said second, third and fourth detection means and the feed shaft motor, for slowing the feed shaft motor down to a predetermined speed when said second detection means detects that the armature current of the spindle motor has continuously exceeded the first preset current value for a period of time greater than the first predetermined time period, and for stopping the feed shaft motor when said third detection means detects that the armature current of the spindle motor has continuously exceeded the second preset current value for a period of time greater than a second predetermined time period.
A system for controlling motor drive in a numerically controlled machine tool having speed command means for generating a speed command signal, a spindle motor, operatively connected to the speed command means, driven to rotate a tool in accordance with the speed command signal, a numerical control device for generating a feed command signal, and a feed shaft motor, operatively connected to the numerical control device, driven to transport a workpiece relative to the tool in accordance with the feed command signal, so that the tool may subject the workpiece to a predetermined machining operation, said system comprising:
- first detection means, operatively connected to the spindle motor, for detecting the armature current of the spindle motor and for generating an armature current signal;
- second detection means for detecting an acceleration or deceleration condition of the spindle motor in dependence upon the speed command signal and for generating an acceleration-deceleration condition signal;
- first commparison means, operatively connected to said first and second detection means, for comparing the value of the armature current signal to a first preset current value and for generating a deceleration command signal when the value for the armature current signal has continuously exceeded the first preset value for a predetermined time period in dependence upon the acceleration-deceleration condition signal;
- and
- control means, operatively connected to said first comparison means, for decelerating the feed shaft motor in dependence upon said deceleration command signal.
Dependencies are inferred from the claim text.