Controller For Machine Tool Including Main Shafts

Abstract

A controller for a machine tool includes a converter converting AC power on the power supply side to DC power, a feed-shaft motor inverter converting DC power on a DC link side and AC power on a feed shaft motor side, first and second main-shaft-motor inverters converting DC power on the DC link side and AC power on first and second main shaft motors side, a power failure detection unit detecting a power failure on the power supply side, a voltage detection unit detecting a DC link voltage value, a feed-shaft-motor command unit outputting a deceleration command to the feed-shaft-motor inverter upon a power failure, and a main-shaft-motor command unit outputting an acceleration / deceleration command to the first main-shaft-motor inverter in accordance with the DC link voltage value and a power shutoff command to the second-main-shaft-motor inverter upon a power failure.

Description

technical field [0001] The present invention relates to a control device for a machine tool having a feed shaft motor for driving a feed shaft and a spindle motor for driving a spindle, and particularly relates to a machine tool protection during power failure that synchronizes the movements of two spindles via a workpiece being held. control device. Background technique [0002] In machine tools having a feed shaft motor and a spindle motor, most of the spindle motors are used, for example, as a drive source for driving a spindle on which workpieces, tools (various tools) are mounted, and the feed shaft motor is used, for example, as a drive source for driving the spindle. The drive source of the moving feed axis. In such a machine tool motor control device, AC power input from an AC input side is once converted into DC power and then converted into AC power, and the AC power is used as driving power for a motor provided for each drive shaft. In such a machine tool, the m...

AI Technical Summary

Problems solved by technology

Since the power-off operation is performed independently between the two spindles, there is a problem that the acceleration and deceleration of the spindle motor is different, and the synchronous relationship between the two spindles held by the gripped workpiece is broken, causing workpiece distortion. Failure such as damage or deformation

[0013] In order to avoid the distortion of the workpiece in the machine tool to which such a power failure backup operation is applied, it is also conceivable to further apply the invention described in the above-mentioned Japanese Patent Application Laid-Open No. 2001-105209, but to slow down the movement of the chuck of one spindle when a power failure occurs. It must be done instantaneously, and the mechanical structure to realize it becomes complicated

In addition, when a power failure occurs, control must be performed, and both the power failure backup operation and the slowdown of the chuck operation of one spindle will inevitably complicate the control system.

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