Motor drive control device for limiting output of motor

Abstract

If it is predicted that the sum of the output of a servo motor and the output of a spindle motor exceeds power supplied by a rectifier unit, during a cutting operation, a motor drive control device controls alternating-current power of a first inverter unit so as to reduce the feed speed of at least one feed axis and controls alternating-current power of a second inverter unit so as not to limit torque of the spindle motor. Further, if it is predicted that the sum of the output of the servo motor and the output of the spindle motor exceeds power supplied by the rectifier unit, during an operation other than the cutting operation, the motor drive control device controls the alternating-current power of the second inverter unit so as to limit the torque so as not to reduce the feed speed.

Description

technical field [0001] The present invention relates to a motor drive control device for driving and controlling at least one servo motor driving a feed axis for moving a table or a tool of a machine tool and a spindle motor having the function of moving the table or tool of a machine tool. A spindle on which the tool rotates. Background technique [0002] In such a motor drive control device, in order to drive and control the servo motor and the spindle motor, the AC voltage or AC current from a commercial AC power source such as a three-phase AC power source is once converted into a DC voltage or DC current, and then converted into a DC voltage or DC current. AC voltage or AC current of any frequency, and the converted AC voltage or AC current is provided to the servo motor and the spindle motor respectively. Therefore, the motor drive control device has a first inverse conversion unit and a second inverse conversion unit. The first inverse conversion unit is connected to...

AI Technical Summary

Problems solved by technology

[0006] In the case of limiting the torque of the servo motor in order to limit the sum of the output of the servo motor and the output of the spindle motor, because the ratio of the output of the servo motor to the sum of the output of the servo motor and the output of the spindle motor is small (for example, 10 %), so it is difficult to effectively limit the sum of the output of the servo motor and the output of the spindle motor

[0007] In addition, when the torque of the servo motor is limited in order to limit the sum of the output of the servo motor and the output of the spindle motor, the followability of the position command of the servo motor deteriorates, which may adversely affect the cutting operation of the workpiece by the machine tool. influences

[0008] On the other hand, when the torque of the spindle motor is limited in order to limit the sum of the output of the servo motor and the output of the spindle motor, in the cutting operation of the workpiece by the machine tool, especially in the heavy cutting operation, due to insufficient torque Sometimes the spindle motor stops and cannot continue the cutting operation, so it may have a bad influence on the cutting operation of the workpiece by the machine tool

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