Thermal displacement compensation method and thermal displacement compensation device for machine tool

Abstract

The invention provides a thermal displacement compensation method for a machine tool and a thermal displacement compensation device. In the thermal displacement compensation method for the machine tool, in which a feed shaft thermal displacement amount is obtained and an amount which cancels the obtained feed shaft thermal displacement amount is added as a thermal displacement compensation amount to a position command for a feed axis, a position where a signal is first output by a position sensor for detecting the position of a movable part of the machine tool is first stored as an initial position. Then, the position where the signal is output by the position sensor is detected, and the thermal displacement compensation amount is modified according to a compensation error, which is the difference between the detected position (actual position) and the initial position.

Description

technical field [0001] The invention relates to a thermal displacement compensation method and a thermal displacement compensation device in a machine tool. Background technique [0002] In a machine tool, the feed screw and the main shaft are driven by a motor, so due to the heat generated by the motor, the frictional heat caused by the rotation of the bearing, and the frictional heat of the meshing portion of the ball screw and ball nut of the feed screw, the main shaft or the feed screw Expansion, displacement of mechanical position. That is, a deviation occurs in the relative positional relationship between the workpiece to be positioned and the tool. Such heat-induced displacement of the mechanical position becomes a problem in the case of high-precision machining. [0003] In order to eliminate the displacement of the mechanical position due to heat, the technique of compensating the thermal displacement simply and at low cost without using a temperature sensor has b...

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Problems solved by technology

[0014] In the technology disclosed in the above-mentioned patent documents, when the variation of the compensation amount is large, instead of using the thermal displacement measured in advance by using an approximate formula, the thermal displacement measured by the sensor is used as the compensation amount, and it is not based on the result measured by the sensor. Since the coefficients of the calculation formula used to estimate the thermal displacement are corrected, the results measured by the sensor are not reflected in the subsequent estimation of the thermal displacement, and the estimation accuracy of the thermal displacement is not high.

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