TIME SHORTENING METHOD FOR WARMING-UP MACHINE TOOL

PURPOSE:To shorten time for warming up a machine tool by a required spindle revolution which is to be continued to the stationary condition of the machine tool in a NC machine and a machine tool equipped with a rotating spindle. CONSTITUTION:Rotation time required to the stationary condition of a machine tool, and the quantity of variation due to the thermal expansion of a spindle at its stationary condition by each required main spindle revolution and by each specified revolution higher in velocity than the each required main spindle revolution, are actually measured so as to be formed into a data base, so that they are store in a NC machine, and the main spindle is then rotated at a specified revolution for the period of time that the quantity of variation for a stationary condition at a designated main spindle revolution is accomplished. Since the quantity of variation at a specified revolution for the same rotation time is greater than that of each required revolution, it becomes clear from the data base. The rotation of the main spindle at a specified revolution by the period of time that the quantity of variation at a designated revolution is accomplished enables time for warming up to be shortened.