Devices for gas cooling plasma arc torches and related systems and methods

1. A nozzle cooling system for a plasma arc torch comprising:

a nozzle having a body with a first end and a second end that define a longitudinal axis, a plenum region substantially formed within the body, the plenum region extending from the first end of the body and configured to receive a plasma gas flow, an exit orifice located at the second end of the body and oriented substantially coaxially with the longitudinal axis, the exit orifice fluidly connected to the plenum region, and a feature on an outer surface of the body configured to increase cooling by receiving a cooling gas flow flowing at high velocity generally in a direction of the longitudinal axis along a length of the body, an impingement surface of the feature configured to receive the cooling gas flow at a substantially perpendicular direction relative to the impingement surface and to redirect the cooling gas flow to promote cooling and uniform shield flow; and

a nozzle retaining cap comprising a generally cylindrical body and a securing flange, the securing flange of the retaining cap including a plurality of shield gas supply ports angled generally along the longitudinal axis of the nozzle at an angle that is substantially perpendicular to the impingement surface of the feature of the nozzle.

2. The nozzle cooling system of claim 1 wherein the nozzle retaining cap comprises about 10 shield gas supply ports.

3. A nozzle-shield cooling system comprising:

a nozzle having a body with a first end and a second end that define a longitudinal axis; a plenum region substantially formed within the body, the plenum region extending from the first end of the body and configured to receive a plasma gas flow; an exit orifice located at the second end of the body and oriented substantially coaxially with the longitudinal axis, the exit orifice fluidly connected to the plenum region; and a feature on an outer surface of the body configured to increase cooling by receiving a cooling gas flow flowing at high velocity generally in a direction of the longitudinal axis along a length of the body, an impingement surface of the feature configured to receive the cooling gas flow at a substantially perpendicular direction relative to the impingement surface and to redirect the cooling gas flow to promote cooling and uniform shield flow; and

a shield for the plasma arc torch comprising a generally conical body and an end face having a shield exit orifice, an interior surface of the shield comprising a mixing chamber at a location corresponding to the impingement feature of the nozzle when assembled together, the mixing chamber comprising an inlet edge positioned to direct the cooling gas from the impingement feature into the mixing chamber.

4. The nozzle-shield cooling system of claim 3 , wherein the mixing chamber and inlet edge extend about a circumference of the interior surface of the shield.

5. The nozzle-shield cooling system of claim 3 wherein a profile of the inlet edge defines an acute angle.

6. The nozzle-shield cooling system of claim 3 wherein the inlet edge extends toward the first end of the nozzle body.

7. The nozzle-shield cooling system of claim 3 wherein the inlet edge extends toward the second end of the nozzle body.

8. The nozzle-shield cooling system of claim 3 wherein the shield comprises at least two inlet edge features.

9. The nozzle-shield cooling system of claim 3 wherein the mixing chamber has a bulbous cross section.

10. The nozzle-shield cooling system of claim 3 wherein the mixing chamber is of sufficient volume to increase a flow uniformity of the cooling gas by performing as a buffering chamber to reduce cooling gas flow transients.