Patent ID: 6215100
Filing Date: 2001-04-10
Classification: B23K

Abstract:
An apparatus for short circuiting arc welding two spaced ends of a first and a second workpiece forming an elongated groove there between which defines a gap by melting an advancing welding wire and depositing said melted wire into said groove to join said two spaced ends, said apparatus comprising: a switching power supply for creating a series of small width current pulses constituting a welding cycle with a short circuit transfer portion and a plasma arc melting portion, said current pulses in said cycle each having a given electrical polarity of said advancing wire with respect to said two metal plates; and, a selector to select the polarity of said pulses in said cycle between a first polarity with said wire being positive and a second polarity with said wire being negative, said selector including a decoder with a first condition for selecting one of said first or second polarity for a first number of consecutive welding cycles and a second condition for selecting the other of said polarity for a second number of consecutive cycles and a switch mechanism to alternate between said first and second conditions during a welding operation.