PULSED DIRECT CURRENT ARC WELDING

摘要

A method of pulsed direct current (DC) arc welding is disclosed wherein special pulses of positive direct current are used to weld together work pieces. The special pulses increase the magnitude of the current flowing across the arc gap to a peak value which can provide sufficient power to melt the work pieces and which is of sufficient magnitude that a power flow is provided which is capable of dissipating oxides on the surfaces of the work pieces during the time interval in which the increase in current flow occurs. Thus, the special DC pulses are capable of dissipating difficult to reduce oxides which may be present on the surfaces of the work pieces without using a flux as required in certain prior arc welding processes. Also, the method according to the present invention is especially useful for fluxless arc welding of aluminum, particularly thin wall aluminum tubing used in making heat exchangers for air conditioning systems, for which conventional alternating current (AC) and DC arc welding techniques are not particularly suitable. Further, the method according to the present invention has the advantage of precise power control to work pieces, a feature not easily or readily attained by many conventional arc welding techniques.