| 摘要 |
A drag cup for a plasma arc torch is mounted on a sleeve member of the torch tip having a conical outer surface portion converging toward the torch nozzle and electro de assembly. The drag cup includes a mounting end, a conical portion extending along the conical p ortion of the sleeve member, and an end radially spaced from and surrounding the torch nozzle and including an end wall spaced axially outwardly of the end of the nozzle and having an opening ther ethrough coaxial with the plasma jet outlet orifice in the nozzle. The opening through the end wal l of the drag cup is 3 to 6 times the size of the nozzle orifice and is large enough to provide a shie lding gas flow about the plasma jet without disturbing the jet and, at the same time is small enough to protect the nozzle against molten metal blow-back through the opening.
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