Method and apparatus for operating an arc-transfer type torch

Claim 1

In the method of operating an arc-transfer type torch having a cathode rod and first and second coaxially spaced annular bodies, the space between the cathode rod and the first annular body defining a first gas flow channel and the space between the first and second annular bodies defining a second gas flow channel, in which a flow of an inactive gas is supplied to the first channel, a flow of an inactive gas is supplied to the second channel and there is established an arc between the cathode and first annular body, the anode foot of which arc is subsequently transferred to the second annular body and thence to a workpiece; the improvement which comprises the steps of reducing the flow rate of the inactive gas in said first channel to a predetermined value above the minimum required to prevent invasion of gas into the first channel and within a flow rate range which, if the flow rate of inactive gas is increased, the wall electrode potential at said second annular body decreases and the heat loss at said second annular body increases; replacing the flow of inactive gas in said second channel with a flow of an active gas; and increasing the arc current to a predetermined value.