Patent ID: 7354386
Filing Date: 2008-04-08
Classification: B23Q,Y10T

Abstract:
1. A thermal displacement correcting device, provided in a machine tool furnished with a spindle device having a spindle for carrying a tool, the spindle device for rotating the spindle on its center axis, and being provided so as to be relatively movable axially, a feeder for relatively moving the spindle device along the spindle axis, a tool changer having a tool magazine in which tools are accommodated, the tool changer for exchanging tools accommodated in the tool magazine with tools attached to the spindle-device spindle, and a controller for controlling operations of the spindle device, the feeder, and the tool changer, the controller configured to control the feeder on the basis of spindle-device target shifting-position data, to relatively move the spindle device to the target shifting position, and configured to control the tool changer on the basis of identification data for an exchange-target tool accommodated in the tool magazine, to exchange the tool corresponding to the identification data with a tool on the spindle, and which corrects thermal displacement axially occurring in the tool carried by the spindle, the thermal displacement correcting device comprising: a log information storage unit for storing as information pertaining to the use log, for each tool accommodated in the tool magazine, temperature directly after that tool's use; a spindle temperature estimating unit for estimating a temperature of the spindle on the basis of an operational status of the spindle device obtained from the controller; a tool temperature estimating unit for recognizing a tool corresponding to the identification data on the basis of the identification data obtained from the controller, reading from the log information storage unit the directly-after-use temperature of the recognized tool, and estimating the tool temperature directly before use on the basis of the read tool temperature and lapsed time, obtained from the controller, since the previous use of said tool corresponding to the identification data, and for estimating a during-use temperature of the tool on the basis of the estimated directly-before-use tool temperature and the temperature of the spindle estimated by the spindle temperature estimating unit, and for storing in the log information storage unit temperature of the spindle-carried tool, directly before tool exchange by the tool changer, as that tool's temperature directly after use; a correction determining unit for estimating an axial thermal displacement of the tool on the basis of the during-use tool temperature estimated by the tool temperature estimating unit, and determining a correction amount for canceling out the displacement; and a correction executing unit for correcting the target shifting position on the basis of the correction amount determined by the correction determining unit.