METHOD FOR CONTROLLING FOCUS POSITION IN LASER WELDING

摘要

PURPOSE: A controlling method of a focus position is provided to focus laser beams extraordinarily and to apply to every welding system. CONSTITUTION: A current value is measured in proportion to strength of a plasma. A plasma signal is converted to a digital signal. A computer to be recorded a signal analysis program analyzes the plasma signal of U-shaped curve. A position having the smallest inclination of a tangent line in the U-shaped curve is set as a focus position. Thereby, the focus position is exactly set without adding an external device. Moreover, the welding efficiency is improved by finding the optimum focus position.