Thermal displacement compensating device for machine tool

摘要

A thermal displacement compensating device calculates a thermal displacement amount which is produced by heat generation or dissipation as a machine tool is actuated or stopped and changes with time. A thermal displacement compensation amount is calculated by multiplying the calculated thermal displacement amount by a coefficient. A position command is compensated by adding the thermal displacement compensation amount to the position command. On the other hand, a variation between a thermal displacement amount calculated last time and a current thermal displacement amount is determined for each predetermined time. A plurality of thermal displacement amount change states are identified based on comparison between the determined variation and a predetermined threshold. The coefficient is calculated based on the identified thermal displacement amount change state.

主权项

1. A thermal displacement compensating device for a machine tool, which comprises a thermal displacement amount calculation unit configured to calculate a thermal displacement amount which is produced by heat generation or dissipation as the machine tool is actuated or stopped and changes with time, a thermal displacement compensation amount calculation unit configured to calculate a thermal displacement compensation amount by multiplying the thermal displacement amount calculated by the thermal displacement amount calculation unit by a coefficient, and a position command compensation unit configured to compensate a position command for a feed shaft by adding the thermal displacement compensation amount to the position command,
the thermal displacement compensating device further comprising: a thermal displacement state identification unit configured to determine a variation between a thermal displacement amount calculated last time and a current thermal displacement amount for each first predetermined time by means of the thermal displacement amount calculation unit and identifying a plurality of thermal displacement amount change states based on comparison between the determined variation and a predetermined threshold; and a coefficient calculation unit configured to calculate the coefficient based on the thermal displacement amount change state identified by the thermal displacement state identification unit.