Patent ID: 8350713
Filing Date: 2013-01-08
Classification: G05B,G07C

Abstract:
1. A numerical controller for controlling a machine, comprising: temperature sensors and relative humidity sensors which are disposed, being placed close together, at individual places of the machine and configured to monitor states of the individual places, or absolute humidity sensors which are disposed at individual places of the machine so as to monitor states of the individual places; and an abnormality determining unit for determining whether the machine is normal or abnormal from detected temperature information and detected relative humidity information obtained from at least one temperature sensor and at least one relative humidity sensor, from among the temperature sensors and the relative humidity sensors which are disposed, being placed close together, at individual places of the machine, or detected absolute information obtained from the absolute humidity sensors which are disposed at individual places, and internal information about the numerical controller which includes at least any one of alarm information about a motor driving unit and alarm information about the numerical controller; wherein the detected temperature information and detected relative humidity information at a time when the machine is powered off and at a time when the machine is powered on are obtained from the temperature sensor and the relative humidity sensor which are disposed, being placed close together, at individual places of the machine so as to monitor states of the individual places, or the absolute humidity information at a time when the machine is powered off and at a time when the machine is powered on is obtained from the absolute humidity sensors which are disposed at individual places of the machine so as to monitor states of the individual places; and wherein the abnormality determining unit has a dew condensation occurrence inferring means configured to use detected temperature information obtained from the temperature sensor, detected relative humidity information obtained from the relative humidity sensor, and a relational equation for temperature and an amount of saturated vapor or uses absolute humidity information obtained from the absolute humidity sensors, resulting in a difference in the amount of water vapor per unit volume in air being obtained between at a time when the machine is powered off and at a time when the machine is powered on as a differential amount of water vapor, and then infers occurrence of dew condensation at a time when the machine is powered on from the obtained differential amount of water vapor; and if the dew condensation inferring means infers occurrence of dew condensation when the alarm information about the motor driving unit or the alarm information about the numerical controller, which are the internal information, is generated, a determination can be made indicating a place of the machine where the temperature sensor and the relative humidity sensor are disposed or where the relevant absolute humidity sensor is disposed is abnormal and the dew condensation is handled as a candidate cause of the alarm information.