Method for detecting abnormality of temperature sensor in machine tool

Abstract

The invention enables an abnormality of a temperature sensor to be simply detected. In S 1 , a temperature measurement is performed with each temperature sensor, and measured signals are digitalized to obtain a temperature value. Then, in S 2 , a detection temperature Tb' equivalent to a detected temperature of a corresponding temperature sensor is calculated with use of an arithmetic expression and a characterization factor stored in a parameter storage device, and in S 3 , an absolute value DeltaT of a temperature difference between Ta and Tb' is obtained. Subsequently, in S 4 , the calculated absolute value DeltaT is compared with a limit value gamma, and when DeltaT is larger than the limit value gamma, Ta or Tb is determined to be abnormal and an alert is issued with an alarm or the like in S 5 , followed by issuance of a command to a correcting device in S 6 not to change a correction amount set before the abnormality occurs.

Description

technical field [0001] The present invention relates to a method of detecting an abnormality of a temperature sensor used for thermal displacement correction of a machine tool. Background technique [0002] In machine tools, thermal displacement correction methods that correct machining dimensional errors caused by ambient temperature changes or cutting heat are widely used. In this thermal displacement correction method, a temperature sensor such as a thermocouple or a thermistor is installed in a component of a machine tool, and temperature information from the temperature sensor is obtained by a temperature measuring device such as a voltmeter or an ammeter. The thermal displacement is estimated to calculate the correction amount of a moving body such as a spindle or a tool post, and the moving body is controlled based on the correction amount (see Patent Documents 1 to 3). [0003] [Patent Document 1] Japanese Patent Publication No. 61-59860 [0004] [Patent Document 2...

AI Technical Summary

Problems solved by technology

However, for example, an abnormality caused by aging of a thermistor cannot be detected by a temperature sensor or a temperature measuring device alone, and a method of detecting an abnormality by installing a plurality of temperature sensors at the same place and comparing temperature information with each other is used.

Therefore, the number of temperature sensors and temperature measurement devices increases, leading to an increase in cost

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