Plasma arc torch, useful for cutting a metal part, comprises an electrode, a nozzle, an arcing chamber arranged between the electrode and the nozzle, a plasma gas supply conduit arranged upstream of arc chamber, and a plasma gas diffuser

摘要

The plasma arc torch comprises an electrode (3), a nozzle (5), an arcing chamber (10) arranged between the electrode and the nozzle, a plasma gas supply conduit arranged upstream of the arc chamber, a plasma gas diffuser (4) fluidly communicating the supply conduit and the arc chamber, and an intermediate member (24) arranged in the supply conduit upstream of the plasma gas diffuser. The intermediate member comprises a set of internal passages fluidly communicating the supply conduit and the arc chamber through the plasma gas diffuser. The plasma arc torch comprises an electrode (3), a nozzle (5), an arcing chamber (10) arranged between the electrode and the nozzle, a plasma gas supply conduit arranged upstream of the arc chamber, a plasma gas diffuser (4) fluidly communicating the supply conduit and the arc chamber, and an intermediate member (24) arranged in the supply conduit upstream of the plasma gas diffuser. The intermediate member comprises a set of internal passages fluidly communicating the supply conduit and the arc chamber through the plasma gas diffuser. The internal passages include a main internal passage and a secondary internal passage. The secondary internal passage has a section lower than a section of the main internal passage. The internal passages are recesses of cylindrical form. The intermediate element is arranged in the supply conduit so as to delimit an upstream part and a downstream part of the supply conduit. Each internal passage comprises an upstream opening emerging in the upstream part of the supply conduit and a downstream opening emerging in the downstream part of the supply conduit. The torch further comprises a first torch component formed by the electrode, the gas diffuser and the supply conduit to selectively seal the downstream opening of the internal passages, a second torch component formed by an electrode holder, a conduit carrier and a insulating block, and a third torch component different from the first torch component, formed by the electrode holder, the conduit carrier and the insulating block and including a second peripheral wall defining a part of the supply conduit. The intermediate element is interdependent the second torch component. The intermediate element, the first torch component and the second torch component are symmetrical with a revolution around a same longitudinal axis. The intermediate element extends from the longitudinal axis. The intermediate element is a shoulder formed on a first peripheral wall of the second torch component and projecting across the supply conduit. The intermediate element transversely extends from the supply conduit until defining a first contact area between the intermediate element and a third peripheral wall. A first sealing unit is arranged on the level of the first contact area. The intermediate element includes a downstream face on the level of the downstream opening of the internal passages. The second torch component includes an upstream face arranged compared to the downstream face. A second contact area is defined between the intermediate element and the second torch component. The second contact area is located between the downstream face and the upstream face or between the downstream face and the first peripheral wall. A second sealing unit is arranged on the level of the second contact area. An independent claim is included for a method for cutting a metal part.