Arc torch nozzle shield for plasma

A shield member for a plasma arc torch that pierces and cuts a metallic workpiece and is so piercing and cutting produces a splattering of molten metal directed at the torch, the shield member protecting a nozzle having a central exit port through which a plasma jet exits and attaches to the workpiece, the shield member comprising:

• a generally cylindrical sidewall and an end wall extending generally transversely to the plasma jet exiting the nozzle, said sidewall and said end wall being formed of a metallic material with good heat transfer properties;
• an exit orifice formed in said end wall generally aligned with said nozzle exit port and having a sufficiently large cross sectional area that it does not interfere with said arc, while being sufficiently small that substantially all of the splattered molten metal strikes the shield member without reaching the nozzle,
• at least one bleed port formed in said shield member and sized and located to divert a first portion of a cooling gas flowing toward the exit orifice between said shield member and the nozzle to the exterior of said shield member so that the remaining second portion of the gas flow impinging on the plasma arc does not destabilize it, and
• means for securing the shield member to the torch with said end wall and sidewall of the shield in a spaced relationship with the nozzle to define therebetween a flow path for the cooling gas flow.