ELECTRIC ARC WELDER USING HIGH FREQUENCY PULSES AND NEGATIVE POLARITY

摘要

An electric arc welder including a high speed switching power supply (10) with a controller for creating high frequency current pulses (110) with negative polarity components through the gap (g) between a workpiece (W) and a welding wire (E) advancing toward the workpiece (W), where the pulses and a background current defining a series of weld cycles. A wave shape generator defines the shape of the pulses (110) and the background current including a controlled ramp up and/or ramp down in each of said cycles, and a circuit to change the shapes of the pulses and/or background current in a repeating pattern in each of the weld cycles, including a negative current in at one of said pulses. The shape change in a cycle can be between first and second shapes or by a rhythmic AC modulation.