Patent ID: 8077327

Claim:
A method for controlling a machine tool in which a work mounted on a table is machined through relative movement in X, Y and Z axis directions between the table and a main spindle, comprising: a step of irradiating laser beam from an emitting element towards an photosensitive element provided on the table respectively, a step of interrupting the laser beam by making a measuring tool attached to the main spindle move towards the laser beam in the direction substantially at right angle therewith through a relative movement between the main spindle and the table, a step of delivering detection signal of interruption when the measuring tool has interrupted the laser beam, a step of measuring coordinate value for each of said three axes based on said detection signal of interruption, and a step of obtaining displacement value between the main spindle and the table through operation processing of the difference between said measured coordinate value for each of the three axes and the measured coordinate value for each of the three axes measured before similarly and update values for correction of positions of the main spindle and/or the table based on said obtained displacement value, wherein said measuring tool is formed with the interrupting portion of the laser beam shaped as a portion of circular cone form, and said machine tool is controlled with correction of position being performed based on the obtained data.