Controller for laser beam machining for controlling approaching operation of machining head

A controller for laser beam machining for machining an object by irradiating a laser beam thereto from a machining head at a reference gap position situated at a predetermined distance away from the object, the controller comprising:

• a gap sensor for detecting an amount of gap between the machining head and the object;
• a gap position command calculation part for producing a gap position command in cooperation with the gap sensor;
• a servo mechanism part for driving the machining head to the reference gap position based on the gap position command;
• a servo position deviation reading part for reading an amount of position deviation of the servo mechanism part;
• a position gain calculation part for calculating a corrected position gain of the servo mechanism part, based on the amount of position deviation of the servo mechanism part;
• and
• a position gain replacing part for replacing the position gain of the servo mechanism part with the corrected position gain calculated by the position gain calculating part.