Plasma arc torch tip providing a substantially columnar shield flow

A torch tip for a plasma arc torch for marking or cutting a metallic workpiece, the plasma arc torch having a hollow torch body which includes a plasma chamber in which a plasma arc is formed, the torch tip comprising:

• a nozzle mounted relative to an electrode in the torch body to define the plasma chamber, the nozzle comprising a hollow nozzle body portion and a substantially solid nozzle head portion formed integrally with the nozzle body portion and defining a nozzle exit orifice extending therethrough;
• and
• a shield which includes (1) a shield body portion with a fastening mechanism for securing the shield to the torch body in a spaced relationship relative to the nozzle such that a shield gas passes through a space between the shield body and the nozzle body portion and (2) a shield head portion formed integrally with the shield body portion and defining a shield exit orifice having an inlet and an outlet, the shield exit orifice dimensioned such that the nozzle head portion extends to a position between the inlet and the outlet of the shield exit orifice (a) to provide a substantially columnar flow of the shield gas that passes through a gap between the shield head portion and the nozzle head portion, the substantially columnar flow surrounding the plasma arc without substantially interfering with the plasma arc and (b) such that the nozzle head portion is recessed within the shield head portion relative to said outlet of said shield exit orifice to prevent a substantial portion of splattered molten metal produced during marking or cutting of the workpiece from reaching the nozzle.

A shield for a plasma arc torch for marking or cutting a metallic workpiece, the plasma arc torch having a torch body and an electrode and a nozzle mounted in the torch body to define a plasma chamber in which a plasma arc is formed, the nozzle having a nozzle exit orifice through which the plasma arc passes, the shield comprising:

• a hollow shield body having (1) a generally cylindrically shaped shield upper body portion with a fastening mechanism for securing the shield to the torch body in a spaced relationship relative to the nozzle such that a shield gas passes through a space between the shield body and a nozzle body portion and (2) a substantially conically shaped shield lower body portion, formed integrally from the shield upper body portion;
• and
• a shield head portion formed integrally with the shield lower body portion and defining a shield exit orifice having an inlet and an outlet, the shield exit orifice dimensioned such that a nozzle head portion can extend to a position between the inlet and the outlet of the shield orifice (1) to provide a substantially columnar flow of the shield gas that passes through a gap between the shield head portion and the nozzle head portion, the substantially columnar flow surrounding the plasma arc without substantially interfering with the plasma arc and (2) such that the nozzle head portion is recessed within the shield head portion relative to said outlet of said shield exit orifice to prevent a substantial portion of splattered molten metal produced during marking or cutting of the workpiece from reaching the nozzle.

A method of operating a plasma arc torch for marking or cutting a metallic workpiece, the method comprising:

• providing a torch body which includes a plasma chamber formed by mounting a nozzle in a spaced relationship relative to an electrode, the nozzle comprising a hollow nozzle body portion and a substantially cylindrical solid nozzle head portion formed integrally with the nozzle body portion and defining a nozzle exit orifice extending therethrough;
• securing a shield, comprising a shield body and a shield head defining a shield exit orifice, to the torch body in a spaced relationship relative to the nozzle such that the nozzle head portion extends to a position between an inlet and an outlet of the shield exit orifice
• passing a plasma gas to the plasma chamber to form a plasma arc therein;
• passing the shield gas through the space between the shield body and the nozzle body portion (1) to provide a substantially columnar flow of shield gas surrounding the plasma arc without substantially interfering with the plasma arc and (2) such that the nozzle head portion is recessed within the shield head portion relative to said outlet of said shield exit orifice to prevent a substantial portion of splattered molten metal produced during marking or cutting of the workpiece from reaching the nozzle.