Servo motor controlling device

Abstract

The invention provides a servo motor controlling device, which includes a speed instruct producing portion for producing speed instructs of the servo motor in each determined period; a reverse rotation detection portion for detecting the reverse rotation of the servo motor in each determined period; a reverse rotation compensation computation portion for computing the reverse rotation compensation for the delay of the servo motor caused by the reverse rotation of the servo motor in case that the reverse rotation is detected by the reverse rotation detection portion; an acceleration instruction computation portion for computing acceleration instruct according to the speed instruct produced by the speed instruct producing portion in each determined period; a pre-reverse rotation acceleration instruct storage portion and a post-reverse rotation acceleration instruct storage portion for storing acceleration instructs before and after the detection of the reverse rotation of the servo motor; and an adjustment portion for adjusting the reverse rotation compensation according to the acceleration instruct and any two from the acceleration before and after. Therefore, even in case of acceleration change before and after the reverse rotation of the servo motor, the machining can be smoothly performed.

Description

technical field [0001] The present invention relates to a servomotor control device for controlling a servomotor, particularly for controlling each of two motors used in a two-axis machine tool. Background technique [0002] In a two-axis machine tool, the workpiece is machined in a desired shape by moving a table on which the workpiece is placed or a machining tool in two directions perpendicular to each other. Figure 8 It is a graph showing the machining error control when the workpiece is machined along an arc-shaped trajectory. exist Figure 8 , the center of the arc-shaped trajectory is taken as the origin. In addition, in Figure 8 In , it is assumed that a table or a machining tool (hereinafter abbreviated as "machining tool, etc.") is rotated clockwise by a first servo motor driving an X-axis and a second servo motor driving a Y-axis. Figure 8 The solid line in is the position instruction of the machining tool determined according to the machining program of the wo...

AI Technical Summary

Problems solved by technology

[0006] However, when the workpiece is machined along a trajectory with a complex shape, for example, when the trajectory is composed of many small line segments, not only the reverse rotation of the servo motor frequently occurs, but also the acceleration changes before and after the rotation.

[0007] In such a case, it is difficult to completely eliminate the influence of invalid travel during reverse rotation, even if the above-mentioned correction is carried out under the premise of constant acceleration.

Therefore, sometimes a protrusion is generated at the processing position of the workpiece because the correction amount is too small, and problems such as damage or recesses occur at the processing position because the correction amount is too large and the processing is performed.

In particular, when damage or recesses occur at the processing position, if such damage cannot be corrected, the workpiece to be processed becomes a defective product.

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