Cooling plasma torch nozzles and related systems and methods

1. A nozzle for a plasma arc torch, the nozzle comprising:

a first body having a first tip end, a second end, and a longitudinal axis; and

a second body disposed about a portion of the first body to complement the first body, the second body comprising a set of axial features extending inwardly from an internal surface of the second body, the axial features having a radial height sufficient to form a surface-to-surface seal between the first body and the second body, the axial features being shaped to form a set of longitudinal liquid flow passages forming a coolant loop between the first body and the second body,

the second body at least partially defining at least one coolant inlet and at least one coolant outlet to the set of longitudinal liquid flow passages; and

a fluid seal formed between the first body and the second body at or near the first tip end to limit liquid within the coolant loop from exiting the nozzle at the tip end of the nozzle,

the set of liquid flow passages defined by the axial features being configured to:

receive a liquid coolant from the at least one inlet;

direct the liquid coolant distally between the first body and second body toward the tip end; and

direct the liquid coolant around the axial features to reverse direction and flow proximally away from the tip end and expel the liquid coolant from between the first body and second body through the at least one outlet.

2. The nozzle of claim 1 wherein the second body is formed of an electrically insulative material.

3. The nozzle of claim 1 wherein an outer surface of the second body defines a set of annular channels, a first annular channel of the set is fluidly connected to the at least one inlet and a second annular channel of the set is fluidly connected to the at least one outlet.

4. The nozzle of claim 1 wherein the first body is rotationally symmetric about the longitudinal axis.

5. The nozzle of claim 1 wherein the coolant loop includes at least one annular passage, at least one of the annular passages being formed at an end of the set of longitudinal liquid flow passages.

6. The nozzle of claim 1 wherein the second body comprises an electrically insulative portion.

7. A nozzle for a liquid-cooled plasma arc torch, the nozzle comprising:

a first body comprising a distal end, a proximal end, and a central axis;

a shell, formed of a non-electrically conductive material, disposed about a portion of the first body, the first body and the shell together defining a set of axial features extending inwardly from an internal surface of the second body, the axial features having a radial height sufficient to form a surface-to-surface seal between the first body and the second body, the axial features being shaped to form a set of longitudinal liquid flow passages forming a coolant loop between the first body and the shell; and

a fluid seal formed between the first body and the shell at or near the distal end to limit liquid within the coolant loop from exiting the nozzle at the distal end of the nozzle,

the set of longitudinal liquid flow passages defined by the axial features being configured to:

receive a liquid coolant from an inlet;

direct the liquid coolant distally between the first body and shell toward the distal end; and

direct the liquid coolant around the axial features to reverse direction and flow proximally away from the distal end and expel the liquid coolant from between the first body and the shell through an outlet.

8. The nozzle of claim 7 wherein the non-electrically conductive material comprises a plastic material.

9. The nozzle of claim 7 wherein the shell is substantially fully formed of the non-electrically conductive material.

10. The nozzle of claim 7 wherein the shell is partially formed of an electrically conductive material.

11. The nozzle of claim 10 wherein the shell comprises a coating of the non-electrically conductive material.

12. The nozzle of claim 11 wherein the coating is formed along an exterior surface of the shell.

13. The nozzle of claim 7 wherein the first body and the shell are snap-fit to one another.

14. The nozzle of claim 7 wherein the shell limits electrical arcing between the nozzle and an adjacent shield.

15. A nozzle for a liquid-cooled plasma arc torch, the nozzle comprising:

a first body having a first end, a second end, and a longitudinal axis, the first body comprising an outer axial alignment flange having a proximal surface configured to mate with a torch body and an opposing distal surface exposed to liquid coolant flow; and

a second body disposed about a portion of the first body, the second body comprising:

an outer surface defining a set of annular channels, at least one inlet to a liquid coolant loop being at least partially defined within a first annular channel of the set and at least one outlet to the liquid coolant loop being at least partially defined within a second annular channel of the set,

the liquid coolant loop being at least partially formed by a set of fluid flow passages defined by a set of axial features forming a surface-to-surface seal between the first body and the second body, the set of fluid flow passages being configured to:

receive a liquid coolant from the at least one inlet;

direct the liquid coolant distally between the first body and second body toward the first end; and

direct the liquid coolant around the axial features to reverse direction and flow proximally away from the first end and expel the liquid coolant from between the first body and second body through the at least one outlet;

the distal surface of the alignment flange and the first annular channel together forming the inlet.

16. The nozzle of claim 15 wherein the first annular channel is disposed at a closer longitudinal position to the second end than the second annular channel.

17. The nozzle of claim 15 wherein the first annular channel and the second annular channel are separated by an annular flange extending from the outer surface of the second body.

18. The nozzle of claim 15 wherein the at least one inlet spans about 5 percent to about 35 percent of the circumference of the second body.

19. The nozzle of claim 15 wherein the first annular channel is also defined by the alignment flange.

20. The nozzle of claim 19 wherein an axial length of the first annular channel is greater than an axial length of the second annular channel.