US Patent No. 9,092,025

THERMAL DISPLACEMENT COMPENSATING DEVICE FOR MACHINE TOOL


Patent No. 9,092,025
Issue Date July 28, 2015
Title Thermal Displacement Compensating Device For Machine Tool
Inventorship Susumu Maekawa, Yamanashi (JP)
Assignee FANUC CORPORATION, Yamanashi (JP)

Claim of US Patent No. 9,092,025

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.