Method for controlling a machine tool and apparatus therefor

摘要

Relative movement in X, Y and Z axis directions is made between a main spindle and a table 6 for application in a machine tool in which a work is machined. An emitting element 12 for irradiating laser beam 11 and a photosensitive element 13 are disposed on the table 6. A measuring tool 8 with its top end being shaped as a cone form is attached to the main spindle 4. The laser beam 11 is interrupted with the cone form portion 15 of the measuring tool 8 through relative movement between the table 6 and measuring tool 8 before and after machining a work. Detection signal of interruption is generated at the moment of interruption, position is detected, operation processing is performed so that difference in X, Y and Z axes before and after machining is obtained along with values for correction. Positional coordinate values for three axis directions are detected simultaneously with a measuring device of a simple constitution by use of laser beam and values for correction such as of thermal displacement is obtained by operation processing of displacement values.