Liquid-cooled plasma arc welding torch

Abstract

A plasma arc torch includes a cathode extending along an axis of the torch, an arc conductor, and a nozzle body. A first fluid conduit and a second fluid conduit extend parallel to the axis of the torch. A first offset fitting includes: a first conduit coupled to and in fluid communication with the first fluid conduit; and a second conduit in fluid communication with the first conduit, radially offset from the first conduit, and extending away from the first conduit in a proximal direction. A second offset fitting includes: a third conduit coupled to and in fluid communication with the second fluid conduit; and a fourth conduit in fluid communication with the third conduit, radially offset from the third conduit, and extending away from the third conduit in the proximal direction. A spring compression plug electrically connects the arc conductor to the nozzle body.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 62 / 932,550 filed on November 8, 2019, U.S. Non-Provisional Patent Application Serial No. 16 / 893,563 filed on June 5, 2020, and U.S. Non-Provisional Patent Application Serial No. 17 / 060,203 filed on October 1, 2020, the disclosures of which are incorporated herein by reference. Background of the Invention Technical Field

[0004] The present invention relates to a liquid-cooled plasma arc torch for cutting a workpiece using a plasma arc.

[0005] Description of related technologies

[0006] In many cutting operations, plasma arc torches are used. These torches operate at very high temperatures, which may damage many parts of these torches. As such, some torches use liquid cooling to transfer heat away from some cutting torch parts. The cooling liquid passes through various fluid chambers within the torch and then returns from the torch and recirculates. The plasma arc torch may use both plasma gas and shielding gas during operation, and may include a high-frequency starting circuit for initiating the arc. Therefore, the plasma arc torch may include an internal conduit for different fluids (e.g., cooling liquid and plasma and shielding gas) passing through the torch, and a conductor for initiating the arc. This structure affects the diameter or width of the torch. Narrower torch designs are generally required because narrower torches can be more easily used in "tight" spaces, such as in the internal corners of a workpiece. An example workpiece with an internal corner that may be difficult to cut is a wide flange beam (e.g., a W-beam or H-beam) or an I-beam with a wide flange, the beam having an internal corner where the beam flange meets the center web. The width of conventional welding torches can make it difficult to maneuver such torches within the interior corners of a workpiece. A narrower welding torch design is also desirable because it allows the use of smaller diameter consumables (e.g., electrodes, nozzles, swirl rings, etc.), thereby reducing the cost of the welding torch and consumables. Further limitations and disadvantages of these conventional welding torches will become apparent to those skilled in the art by comparing conventional liquid-cooled plasma arc welding torches with the embodiments of the present invention set forth in the remainder of this application with reference to the accompanying drawings.

[0007] Brief Summary of the Invention

[0008] The following overview presents a simplified overview to provide a basic understanding of some aspects of the devices, systems and / or methods discussed herein. This overview is not an extensive review of the devices, systems and / or methods discussed herein. It is not intended to point out key elements or to delimit the scope of such devices, systems and / or methods. The only purpose is to present some concepts in a simplified form as a preface to a more detailed description presented later.

[0009] According to one aspect of the present invention, a plasma arc torch is provided. The plasma arc torch includes a cathode, an arc conductor, and a nozzle body, wherein the cathode extends along the axis of the torch. A first fluid conduit in the torch extends parallel to the axis of the torch. A second fluid conduit in the torch extends parallel to the axis of the torch. A first offset fitting includes a first conduit in fluid communication with the first fluid conduit and a second conduit in fluid communication with the first conduit. The first conduit is coupled to the first fluid conduit, the second conduit is radially offset outward from the first conduit and extends away from the first conduit in a proximal direction parallel to the axis of the torch. A second offset fitting includes a third conduit in fluid communication with the second fluid conduit and a fourth conduit in fluid communication with the third conduit. The third conduit is coupled to the second fluid conduit, the fourth conduit is radially offset outward from the third conduit and extends away from the third conduit in the proximal direction parallel to the axis of the torch. A spring compression plug electrically connects the arc conductor to the nozzle body.

[0010] According to another aspect of the present invention, a plasma arc torch is provided. The plasma arc torch includes: a cathode extending along the axis of the torch and having a first plurality of cooling liquid orifices; a nozzle; and a nozzle body having an internal cooling liquid passage that delivers cooling liquid toward the nozzle. An internal separator has a second plurality of cooling liquid orifices in fluid communication with the first plurality of cooling liquid orifices. An external separator is radially offset from the internal separator to form a gap space through which the cooling liquid is delivered to the nozzle body. A distal end of the external separator is radially offset from the internal separator so that the gap space extends to a distal end of the external separator. The internal separator and the external separator electrically insulate the nozzle body from the cathode. The torch further includes a cooling liquid return conduit, and a cooling liquid return offset fitting, the cooling liquid return offset fitting including a first cooling liquid return conduit in fluid communication with the cooling liquid return conduit, and a second cooling liquid return conduit in fluid communication with the first cooling liquid return conduit. The first cooling liquid return conduit is coupled to the cooling liquid return conduit, and the second cooling liquid return conduit is radially offset outward from the first cooling liquid return conduit and extends in a proximal direction away from the first cooling liquid return conduit parallel to an axis of the welding torch.

[0011] According to another aspect of the present invention, a plasma arc torch is provided. The plasma arc torch includes a cathode, an arc guide conductor, a nozzle body, a plasma gas conduit, a shielding gas conduit, and a cooling liquid return conduit, wherein the cathode extends along the axis of the torch. A plasma gas offset accessory includes a first plasma gas conduit in fluid communication with the plasma gas conduit, and a second plasma gas conduit in fluid communication with the first plasma gas conduit. The second plasma gas conduit is radially offset outward from the first plasma gas conduit and extends away from the first plasma gas conduit in a proximal direction parallel to the axis of the torch. A shielding gas offset accessory includes a first shielding gas conduit in fluid communication with the shielding gas conduit, and a second shielding gas conduit in fluid communication with the first shielding gas conduit. The second shielding gas conduit is radially offset outward from the first shielding gas conduit and extends away from the first shielding gas conduit in the proximal direction parallel to the axis of the torch. A cooling liquid return offset accessory includes a first cooling liquid return conduit in fluid communication with the cooling liquid return conduit, and a second cooling liquid return conduit in fluid communication with the first cooling liquid return conduit. The second cooling liquid return conduit is radially offset outward from the first cooling liquid return conduit and extends in the proximal direction parallel to the axis of the torch away from the first cooling liquid return conduit.A spring compression plug electrically connects the arc conductor to the nozzle body. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The above and other aspects of the present invention will become apparent to those skilled in the art to which the present invention relates after reading the following description with reference to the accompanying drawings, in which:

[0013] Figure 1 A plasma arc welding torch is shown;

[0014] Figure 2 is an exploded view showing components of a plasma arc torch;

[0015] Figure 3 is an end view of a plasma arc welding torch;

[0016] Figure 4 is a cross-sectional view of a plasma arc welding torch;

[0017] Figure 5 is a cross-sectional view of a plasma arc welding torch;

[0018] Figure 6 is a cross-sectional view of a second embodiment of a plasma arc torch;

[0019] Figure 7 is a cross-sectional view of a second embodiment of a plasma arc torch;

[0020] Figure 8 is a cross-sectional view of a third embodiment of a plasma arc torch;

[0021] Fig. 9 is a cross-sectional view of a third embodiment of a plasma arc torch; and

[0022] Fig.10 Shown is the coolant flow path in a plasma arc torch. DETAILED DESCRIPTION

[0023] The present invention relates to a plasma arc welding torch. The invention will now be described with reference to the accompanying drawings, in which the same reference numerals are used throughout to refer to the same elements. It will be understood that these different figures are not necessarily drawn in a proportional manner to each other, and the same is true within a given figure, and in particular, the sizes of the components are arbitrarily drawn to facilitate the understanding of the drawings. In the following description, for the purpose of explanation, a number of specific details are set forth in order to provide a comprehensive understanding of the invention. However, it may be apparent that the invention can be practiced without these specific details. In addition, other embodiments of the invention are possible and the invention can be practiced and implemented in a manner other than as described. The terms and phrases used in describing the invention are adopted for the purpose of facilitating the understanding of the invention and should not be considered limiting.

[0024] As used herein, "at least one," "one or more," and "and / or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B, and C," "at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C," and "A, B, and / or C" refers to A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B, and C together. Any disjunctive words and / or phrases that give two or more alternative terms, whether in the description of the embodiments, claims, or drawings, should be understood to cover the following possibilities: including one of these terms, any of these terms, or all of the terms. For example, the phrase "A or B" should be understood to include the following possibilities: "A," or "B," or "A and B."

[0025] Discussed herein is a plasma arc torch having, among other things, fluid and electrical connections at an upstream end of the torch and a nozzle and shield at a downstream or cutting end of the torch. The term "proximal end" as used herein refers to the upstream direction of the torch, toward the end of the torch having the fluid and electrical connections. The term "distal end" as used herein refers to the downstream direction of the torch, toward the cutting end of the torch.

[0026] Figure 1 An example plasma arc or plasma cutting torch 100 is shown. The plasma arc torch 100 is a liquid-cooled torch having a narrow proximal end and an even narrower distal end. The torch 100 is attached to a handle portion 102. The handle portion 102 can be clamped into an automated cutting device, such as a computer numerically controlled (CNC) plasma cutting table or a robotic arm. The torch body 104 is at the distal end of the handle portion 102. The torch body 104 can be made of a metallic material and forms a majority of the outer portion of the torch 100. In the example embodiment, the torch body 104 is made of brass. However, the torch body can be made of a variety of different metals and alloys, as will be appreciated by one of ordinary skill in the art. An outer retaining hood 106 is attached to the torch body 104, which secures a protective hood 108 to the torch 100.

[0027] In an exemplary embodiment, the length of the welding torch 100 (from the bottom of the handle portion 102 to the top of the protective cover 108) can be about 7 inches or 178 mm, and the width of the welding torch can be about 1.5 inches or 38 mm. It should be understood that the length and width of the welding torch 100 are exemplary and other dimensions are possible. The narrow width of the welding torch 100 combined with its length can facilitate maneuvering the welding torch near certain workpieces with vertical members or internal corners and cutting the workpieces. Examples of such workpieces include wide flange beams (e.g., W-beams or H-beams with wide flanges of about 14 inches in length), I-beams, or other metal workpieces with internal corners (e.g., bulkheads). The width of the handle portion 102 can be about 2 inches or 51 mm. By making the diameter of the welding torch 100 smaller, small diameter consumables (e.g., electrodes, nozzles, swirl rings, etc.) can be used in the welding torch, which reduces the cost of the welding torch and the cost of the consumables that must be replaced from time to time.

[0028] Figure 2 is an exploded view of a welding torch showing various components and consumables of the welding torch presented along an axis 109 of the welding torch. Figure 2 1 , a torch body 104, an outer retaining shroud 106, and a protective shroud 108 are shown. A nozzle body 110, or anode, and a cooling tube 112 extend from the torch body 104. The cooling tube 112 is attached to a cathode within the torch, as is the electrode 114. The torch further includes a swirl ring 116 and a nozzle 118. The swirl ring 116 and nozzle 118 are held in place by an inner retaining shroud 120, which is threaded onto the nozzle body 110. The electrode 114, swirl ring 116, nozzle 118, inner retaining shroud 120, protective shroud 108, and outer retaining shroud 106 can all be considered consumables of the torch 100.

[0029] Figure 3A proximal end view of a plasma arc torch 100 is shown. Various connections or accessories are located at the proximal end of the torch 100. These accessories include a power and cooling liquid accessory 122, a plasma gas offset accessory 124, a shielding gas offset accessory 126, a cooling liquid return offset accessory 128, a high frequency starting circuit accessory 130 for an arc pilot conductor, and a plate sensing connection 132 for sensing contact between the torch 100 and the workpiece. In addition to the plate sensing connection 132, the accessories are Figure 2 however, other types of connectors may be used. The offset fittings 124, 126, 128 help provide a narrow width for the welding torch 100, as discussed further below.

[0030] Figure 4 1 is a cross-sectional view of a plasma arc torch 100. The power and cooling liquid fitting 122 is located at the proximal end of a coolant supply tube or conduit 134 that directs the current to the cathode 136 and electrode 114 in the torch 100 and also delivers cooling liquid to the distal end of the torch. The cathode 136 penetrates into the distal end of the coolant supply tube 134 and is directed along the axis 109 ( Figure 2 ) extends toward the nozzle 118. The cooling tube 112 and the electrode 114 are attached to the cathode 136. The inner diameter of the electrode 114 is larger than the outer diameter of the cooling tube 112, so that there is a gap space between the electrode and the cooling tube. The cooling liquid is delivered to the distal end of the welding torch 100 through the coolant supply tube 134, the cathode 136 and the cooling tube 112. The cooling liquid then flows in the proximal direction in the gap space between the outer surface of the cooling tube 112 and the inner surface of the electrode 114 to cool the electrode. As will be discussed further below, after cooling the electrode 114, the cooling liquid also flows through the orifice in the cathode 136 and flows through the internal separator 138 and the external separator 140 around the cooling tube and the electrode and flows into the nozzle body 110 to cool the nozzle 118. The internal separator 138 and the external separator 140 electrically insulate the nozzle body 110 from the cathode 136 and the electrode 114.

[0031] At the proximal end of the welding torch 100 is a threaded portion 142 that connects the welding torch to a handle portion (not shown). Extending distally from the threaded portion 142 is an isolator 144 that insulates the welding torch body 104 from the interior portion of the welding torch 100. The threaded portion 142 and the isolator 144 may be integrally formed, or may be formed as separate components. Another isolator 146 is located in the central portion of the welding torch 100. The welding torch body 104 rests on another isolator 146 that may limit or set the axial position of the welding torch body, wherein an internal epoxy is used to prevent rotational movement. Various isolators in the welding torch may be formed of non-metallic materials, such as high temperature plastics. Example high temperature non-metallic materials include PEEK (polyetheretherketone), polyetherimide (e.g., ULTEM), VESPEL, and the like.

[0032] The outer retaining shroud 106 is attached to the torch body 104 and holds the protective shroud 108 in place. The swirl ring 116 and nozzle 118 are held in place by an inner retaining shroud 120, which is threaded onto the nozzle body 110. The swirl ring 116 imparts a swirling motion to the plasma gas as it passes through the swirl ring.

[0033] In addition to the coolant supply pipe 134, Figure 4 1 and 2. Also shown are fluid conduits for plasma and shielding gases. A plasma gas conduit 148 delivers plasma gas to the nozzle body 110. The plasma gas flows through passages in the nozzle body 110 and is exhausted near the swirl ring 116. A shielding gas conduit 150 delivers shielding gas to the nozzle body 110. The shielding gas flows through passages in the nozzle body 110 and is exhausted at a central location along the nozzle body. In the exemplary embodiment, the plasma gas conduit 148 and the shielding gas conduit 150 are aligned with the axis 109 ( Figure 2 However, the plasma gas conduit 148 and the shielding gas conduit 150 can be angled relative to the axis of the torch when desired.

[0034] To help achieve the narrow width of the welding torch 100, offset fittings are used for various fluid connections. The welding torch 100 includes a plasma gas offset fitting 124 attached to a plasma gas conduit 148, and a shielding gas offset fitting 126 attached to a shielding gas conduit 150. The plasma gas offset fitting 124 includes a first plasma gas conduit 152 in fluid communication with the plasma gas conduit 148, and a second plasma gas conduit 154 in fluid communication with the first plasma gas conduit. The first plasma gas conduit 152 is coupled to the plasma gas conduit 148, and the second plasma gas conduit 154 is radially offset outward from the first plasma gas conduit and extends in a proximal direction away from the first plasma gas conduit parallel to the axis of the welding torch 100. The shielding gas offset fitting 126 includes a first shielding gas conduit 156 in fluid communication with the shielding gas conduit 150, and a second shielding gas conduit 158 ​​in fluid communication with the first shielding gas conduit. A first shielding gas conduit 156 is coupled to the shielding gas conduit 148, and a second shielding gas conduit 158 ​​is radially offset outwardly from the first shielding gas conduit and extends in a proximal direction away from the first shielding gas conduit parallel to the axis of the torch 100. It can be seen that the offset fittings / connectors 124, 126 have an inward recess or axial discontinuity toward the center of the torch 100. The offset fittings 124, 126 provide fluid communication between two axially extending conduits or channels that are parallel but radially offset so that fluid can be directed from the proximal end through the torch to the distal end. Conventional plasma arc torches have fittings in a straight line that do not have an inward recess as shown, and therefore conventional torches are wider than the torch of the present invention. At the proximal end of the torch 100, the offset fittings 124, 126 allow for wider spacing between the fluid tubes and the electrical conductors and their connection to the fluid / power source, with tighter spacing between the tubes / conductors along the distal portion of the torch. Instead of an offset fitting, the torch 100 may use a curved fluid tube, but curved fluid tubes are not manufacturing friendly. The offset fitting may be implemented by one or more machined parts, which may include different materials.

[0035] Figure 5 is another cross-sectional view of the plasma arc torch 100 . Figure 5 The cooling liquid return offset fitting 128 and the cooling liquid return conduit 160 are shown. After the distal end of the welding torch 100 is cooled, the cooling liquid flows through the passage in the nozzle body 110 and is delivered to the proximal end of the welding torch through the cooling liquid return conduit 160. In the exemplary embodiment, the cooling liquid return conduit 160 is aligned with the axis 109 ( Figure 2) extends parallel to the axis of the torch. However, the cooling liquid return conduit can be angled relative to the axis of the torch when desired. The cooling liquid return offset fitting 128 is constructed similarly to the plasma gas and shielding gas offset fittings and is attached to the cooling liquid return conduit 160. Similar to the plasma gas and shielding gas offset fittings, the cooling liquid return offset fitting 128 has an inward recess or axial discontinuity toward the center of the torch 100 to reduce the diameter of the torch while maintaining sufficient spacing between the connectors at the proximal end of the torch. The cooling liquid return offset fitting 128 includes a first cooling liquid return conduit 162 in fluid communication with the cooling liquid return conduit 160, and a second cooling liquid return conduit 164 in fluid communication with the first cooling liquid return conduit. The first cooling liquid return conduit 162 is coupled to the cooling liquid return conduit 160, and the second cooling liquid return conduit 164 is radially offset outward from the first cooling liquid return conduit and extends away from the first cooling liquid return conduit in a proximal direction parallel to the axis of the torch.

[0036] Figure 5 Also shown in the figure is a high frequency starting circuit accessory 130 or arc pilot accessory. An arc pilot conductor 166 within the welding torch 100 directs a high frequency starting current from a starting circuit within a plasma cutting power supply (not shown) to the nozzle body 110. The starting current flows through the accessory 130 to the arc pilot conductor and to the nozzle body 110 to form a pilot arc between the electrode 114 and the nozzle 118 during arc starting. A spring compression plug 168 electrically connects the arc pilot conductor 166 to the nozzle body 110. The spring compression plug 168 is similar to a banana plug. In an exemplary embodiment, the spring compression plug 168 is a ferrule connector available from Stauby Electrical Connectors, Inc. ( The nozzle body 110 has a MULTILAM plug connector available from GE Electrical Connectors AG. The nozzle body 110 has a hole that receives a spring compression plug 168. The spring compression plug 168 has a flexible spring element that is compressed when the connector is inserted into the hole. During assembly of the welding torch 100, when the nozzle body 110 is connected to the arc pilot connector 166, the spring compression plug 168 facilitates rotation and repositioning of the nozzle body.

[0037] Figure 6 and Figure 7 A first quick disconnect embodiment of a plasma arc torch 200 is shown. Figure 8 and Fig. 9 A second quick disconnect embodiment of a plasma arc torch 300 is shown. Figure 6 and Figure 7 Plasma arc torch ratio Figure 8 and Fig. 9The welding torch 200, 300 is short. Both welding torches 200, 300 have a torch base 202, which connects the welding torch to a handle portion (not shown). The welding torch head 203, 303 is at the distal end of the welding torch base 202, and the welding torch head is easily separated from the welding torch base. The welding torch head 203, 303 includes a threaded connection collar 204, which secures the welding torch head to the welding torch base and allows the welding torch head to be removed from the welding torch base. When the threaded connection collar 204 is removed from the welding torch base, the fluid and electrical connections between the welding torch head 203, 303 and the welding torch base 202 are separated. Specifically, when the threaded connection collar 204 is removed from the welding torch base, the male adapter in the welding torch head 203, 303 is pulled out of the female socket in the welding torch base 202. Although the quick disconnect connection between the torch base 202 and the torch head 203, 303 is shown as a threaded connection, other quick disconnect connection styles may be used in the torch 200, 300, such as a snap-on or ball latch, bayonet latch, etc.

[0038] exist Figure 6 and Figure 7 In the figure, the outer retaining cover, the inner retaining cover, the protective cover, the nozzle, the swirl ring and the electrode are not shown. The nozzle body 110 and the welding torch body 206 are Figure 6 and Figure 7 206 is shown together with various other torch components discussed above. Figure 4 , Figure 5 , Figure 8 and Fig. 9 The torch body shown in is much shorter. Figure 6 and Figure 7 The fluid conduit and arc conductor in the welding torch embodiment are also shorter.

[0039] The power and cooling liquid fitting 122 is located at the proximal end of the first coolant supply tube 208. The cathode 136 is threaded into the distal end of the second coolant supply tube 210, which can be disconnected from the first coolant supply tube 208 when the torch head 203 is removed from the torch base 202. The torch base 202 includes a female receptacle 212 for supplying cooling liquid and electrical power to the torch head 203, into which the second coolant supply tube 210 is inserted. The second coolant supply tube 210 can include a seal, such as an O-ring that seals against the female receptacle 212.

[0040] The torch base 202 further includes a shielding gas connection 214 and a plasma gas connection 216 and associated female receptacles 218, 220. The torch head 203 includes fluid carrying tubes or adapters 222, 224 that plug into the female receptacles 218, 220. The fluid carrying tubes or adapters 222, 224 may include seals, such as O-rings that seal against the female receptacles 218, 220. Although a female receptacle is shown in the torch base 202 and a male plug is shown in the torch head 203, this is merely exemplary and any of the connections discussed herein may be modified such that the male plug is in the torch base and the female receptacle is in the torch head.

[0041] A fluid carrier tube or adapter 222 for shield gas is threaded into a shield gas offset fitting 226, and a fluid carrier tube or adapter 224 for plasma gas is threaded into a plasma gas offset fitting 228. The shield gas offset fitting 226 delivers the shield gas to a short shield gas conduit 230, and the plasma gas offset fitting 228 delivers the plasma gas to a short plasma gas conduit 232. The shapes of the conduits within the shield gas offset fitting 226 and the plasma gas offset fitting 228 are similar to those described above with respect to Figure 4 and Figure 5 The offset fittings are discussed because they have an inward indentation or axial discontinuity toward the center of the torch 200 and they extend parallel to each other in opposite directions.

[0042] Figure 7 2 and 3. The cooling liquid return fitting 234 and the high frequency starting circuit fitting 236 or arc pilot fitting are shown in FIG. The torch base 202 includes a female receptacle 238 for a cooling liquid return fluid carrying tube or adapter 240, which can be sealed against the receptacle as discussed above. The cooling liquid return fluid carrying tube or adapter 240 is threaded into a cooling liquid return offset fitting 242. The cooling liquid return offset fitting 242 delivers cooling liquid returned from the nozzle body 110 to the proximal end of the torch. The cooling liquid return offset fitting 242 receives cooling liquid from a short cooling liquid return conduit 244, which flows through the offset fitting to the adapter 240 and into the torch base 202.

[0043] The high frequency starting circuit accessory 236 or arc pilot accessory is electrically connected to the arc pilot conductor 246 through the adapter plug 248 in the welding torch head 203. The arc pilot conductor 246 has an inward recess toward the center of the welding torch 200, similar to the offset accessories discussed above for fluid flow through the welding torch. Figure 5 A spring compression plug 250 , similar to the spring compression plug discussed above, electrically connects the arc conductor 246 to the nozzle body 110 .

[0044] Because the welding torch 200 can be disconnected frequently, it is possible for coolant to drip into the welding torch when the welding torch is disconnected. Coolant can accumulate in the internal voids in the welding torch 200 and increase the possibility of undesirable arc formation or arc discharge within the welding torch. In order to reduce the possibility of such arc discharge events, the offset fittings 226, 228, 242 can be constructed of a high temperature non-metallic, electrically insulating material (such as a high temperature plastic). Example high temperature non-metallic, electrically insulating materials include PEEK (polyetheretherketone), polyetherimide (e.g., ULTEM), VESPEL, etc. The offset fittings 226, 228, 242 act as electrical insulators. An axially extending isolator 252 is at the distal end of the offset fittings 226, 228, 242, and the isolator is located between the welding torch body 206 and the nozzle body 110. The offset fittings 226, 228, 242 and the isolator 252 can be integrally or integrally formed, or can be formed as separate components. Furthermore, the offset fittings 226, 228, 242, and the passageway for the arc conductor 246 may be integrally or unitarily formed from high temperature non-metallic materials as a single isolator component with the various conduits described above, or they may be formed as two or more separate components.

[0045] As pointed out above, Figure 8 and Fig. 9 A second quick disconnect embodiment of a plasma arc torch 300 is shown. Figure 6 and Figure 7 The torch length shown in is Figure 8 and Fig. 9 The welding torch shown in FIG. 300 has features that have been discussed above, so they will not be discussed in detail. The proximal half of the welding torch 300 includes a welding torch base 202, and a threaded connection collar 204 on a welding torch head 303 for disconnecting the welding torch head from the welding torch base. The welding torch head 303 also includes an offset fitting and a male fluid carrying tube or adapter, and an arc pilot adapter plug, which is plugged into a corresponding female receptacle in the welding torch base 202, as described above with respect to Figure 6 and Figure 7 The distal half of the welding torch 300 is structurally similar to Figure 4 and Figure 5 Similar to the welding torch shown and discussed above.

[0046] Fig.10 The coolant flow path at the distal end of the plasma arc torch 100 is shown. Fig.10 yes Figure 5 Detailed view of a cross section of the distal end of the torch 100 is shown. However, the coolant flow path shown and described also applies to Figures 6 to 9 A welding torch embodiment. Fig.101 and 1 . The flow path of the cooling liquid at the distal end of the welding torch 100 is shown by arrows. The cooling liquid is delivered to the distal end of the welding torch 100 through the coolant supply tube, the cathode 136, and the cooling tube 112. The inner diameter of the electrode 114 is larger than the outer diameter of the cooling tube 112, so that there is a gap space between the electrode and the cooling tube. Initially, the cooling liquid flows in the cooling tube 112 toward the distal end of the electrode 114. Then, as shown, the cooling liquid flows in the electrode 114 in the gap space between the outer surface of the cooling tube 112 and the inner surface of the electrode 114 in the proximal direction to cool the electrode. The cathode 136 has a first plurality of cooling liquid orifices 400. The orifices 400 can be arranged as a circle of holes through the cathode wall, which are circumferentially located around the cathode 136 and allow the cooling liquid to escape radially (in the radial direction) from the cathode. The internal separator 138 located around the cathode 136 and the electrode 114 has a second plurality of cooling liquid orifices 402. Similar to the orifices 400 in the cathode 136, the second plurality of cooling liquid orifices 402 can be arranged as a circle of holes through the inner separator 138. The first plurality of cooling liquid orifices 400 and the second plurality of cooling liquid orifices 402 are in fluid communication so that cooling liquid can flow radially through the cathode 136 and through the inner separator 138, as shown. In certain embodiments, the first plurality of cooling liquid orifices 400 and the second plurality of cooling liquid orifices 402 are aligned with each other; however, if the cooling liquid can flow circumferentially between the cathode 136 and the inner separator 138, the orifices 400, 402 do not need to be aligned with each other. The outer separator 140 is radially offset from the inner separator 130 to form an interstitial space through which the cooling liquid is delivered into the nozzle body 110. After the cooling liquid flows in the proximal direction between the cooling tube 112 and the cathode 114, the cooling liquid flows radially through the first plurality of orifices 400 and the second plurality of orifices 402, and then flows in the distal direction in the interstitial space between the inner separator 138 and the outer separator 140. The cooling liquid then flows into one or more openings in the nozzle body 110 and flows distally through a plurality of internal cooling liquid passages 404 in the nozzle body. The internal cooling liquid passages 404 in the nozzle body 110 are short and narrow, such as less than one inch in length (e.g., less than 25 mm), less than 0.1 inches in diameter (e.g., less than 0.25 mm), and together provide a small pressure drop for cooling the cooling fluid. In the example embodiment, the nozzle body 110 includes three internal cooling liquid passages 404; however, it should be understood that the nozzle body may include less than three or more than three cooling liquid passages, depending on the cooling requirements of the welding torch. The cooling liquid exits the internal cooling liquid passages 404 in the nozzle body 110 and flows between the inner retaining shroud 120 and the nozzle 118 to cool the nozzle.The cooling liquid then flows into another opening in the nozzle body 110 and flows proximally through the second internal cooling liquid passage 406. The second internal cooling liquid passage 406 is in fluid communication with the cooling liquid return conduit 160 for recirculation from the welding torch 100.

[0047] As can be seen, the distal end of the outer isolator 140 is radially offset from the inner isolator 138 so that the interstitial space between the isolators extends to the distal end of the outer isolator. The proximal end of the inner isolator 138 contacts the inner wall of the outer isolator 140, and the second plurality of cooling liquid orifices 402 are located just distal to the proximal end of the inner isolator. The inner isolator 138 extends at the distal end of the outer isolator 140 and the outer isolator extends at the proximal end of the inner isolator. The outer isolator 140 has no cooling liquid orifices, such as those found on the inner isolator 138. The inner isolator 138 and the outer isolator 140 provide a low pressure drop for the cooling liquid without reducing the arc discharge distance separating the conductive portions of the plasma arc torch 100.

[0048] It should be clear that the present disclosure is by way of example, and that various changes may be made by adding, changing or removing details without departing from the reasonable scope of the teachings contained in the present disclosure. Therefore, the present invention is not limited to the specific details of the present disclosure, unless the appended claims are necessarily so limited.

Claims

1. A plasma arc welding torch comprising: a cathode extending along an axis of the welding torch; Arc conductor; Nozzle body; a first fluid conduit within the welding torch, the first fluid conduit extending parallel to an axis of the welding torch; a second fluid conduit within the welding torch, the second fluid conduit extending parallel to an axis of the welding torch; a first offset fitting comprising a first conduit in fluid communication with the first fluid conduit and a second conduit in fluid communication with the first conduit, wherein the first conduit is coupled to the first fluid conduit, the second conduit being offset radially outward from the first conduit and extending in a proximal direction parallel to an axis of the torch away from the first conduit; as well as a second offset fitting including a third conduit in fluid communication with the second fluid conduit and a fourth conduit in fluid communication with the third conduit, wherein the third conduit is coupled to the second fluid conduit, the fourth conduit being offset radially outward from the third conduit and extending in the proximal direction parallel to an axis of the torch away from the third conduit; as well as a spring compression plug electrically connecting the arc conductor to the nozzle body; wherein the cathode comprises a first plurality of cooling liquid orifices, and the nozzle body comprises an internal cooling liquid passage for conveying cooling liquid toward a nozzle of the welding torch, wherein the welding torch further comprises: an internal isolator having a second plurality of cooling liquid orifices in fluid communication with the first plurality of cooling liquid orifices; and an outer separator radially offset from the inner separator to form an interstitial space through which the cooling liquid is delivered into the nozzle body, wherein a distal terminal end of the outer separator is radially offset from the inner separator such that the interstitial space extends to a distal terminal end of the outer separator, and the inner separator extends distally of the outer separator and the outer separator extends proximally of the inner separator, and wherein the inner separator and the outer separator electrically insulate the nozzle body from the cathode.

2. The plasma arc torch according to claim 1, wherein: The internal cooling liquid passage is less than one inch in length and less than 0.1 inches in diameter.

3. The plasma arc torch according to claim 1, wherein: The proximal terminal end of the inner isolator contacts an inner wall of the outer isolator, and the second plurality of cooling liquid orifices are located distal to the proximal terminal end of the inner isolator.

4. A plasma arc welding torch comprising: a cathode extending along an axis of the torch and having a first plurality of cooling liquid orifices; nozzle; a nozzle body having an internal cooling liquid passage that delivers cooling liquid toward the nozzle; an internal isolator having a second plurality of cooling liquid orifices in fluid communication with the first plurality of cooling liquid orifices; an outer separator radially offset from the inner separator to form an interstitial space through which the cooling liquid is delivered into the nozzle body, wherein a distal terminal end of the outer separator is radially offset from the inner separator such that the interstitial space extends to a distal terminal end of the outer separator and the inner separator extends at a distal end of the outer separator and the outer separator extends at a proximal end of the inner separator, and wherein the inner separator and the outer separator electrically insulate the nozzle body from the cathode; a cooling liquid return conduit; and A cooling liquid return offset fitting comprising a first cooling liquid return conduit in fluid communication with the cooling liquid return conduit, and a second cooling liquid return conduit in fluid communication with the first cooling liquid return conduit, wherein the first cooling liquid return conduit is coupled to the cooling liquid return conduit and the second cooling liquid return conduit is radially offset outward from the first cooling liquid return conduit and extends in a proximal direction parallel to the axis of the welding torch away from the first cooling liquid return conduit.

5. The plasma arc torch according to claim 4, wherein: The internal cooling liquid passage is less than one inch in length and less than 0.1 inches in diameter.

6. The plasma arc torch of claim 4, wherein: The proximal terminal end of the inner isolator contacts an inner wall of the outer isolator, and the second plurality of cooling liquid orifices are located distal to the proximal terminal end of the inner isolator.

7. The plasma arc torch of claim 4, further comprising: plasma gas duct; as well as A plasma gas offset accessory, the plasma gas offset accessory including a first plasma gas conduit in fluid communication with the plasma gas conduit, and a second plasma gas conduit in fluid communication with the first plasma gas conduit, wherein the first plasma gas conduit is coupled to the plasma gas conduit, and the second plasma gas conduit is radially offset outward from the first plasma gas conduit and extends away from the first plasma gas conduit in the proximal direction parallel to the axis of the welding torch.

8. The plasma arc torch of claim 4, further comprising: Shielding gas conduit; as well as A shielding gas offset accessory, the shielding gas offset accessory comprising a first shielding gas conduit in fluid communication with the shielding gas conduit, and a second shielding gas conduit in fluid communication with the first shielding gas conduit, wherein the first shielding gas conduit is coupled to the shielding gas conduit, and the second shielding gas conduit is radially offset outward from the first shielding gas conduit and extends away from the first shielding gas conduit in the proximal direction parallel to the axis of the welding torch.

9. The plasma arc torch of claim 4, further comprising: Arc conductor; as well as A spring compression plug electrically connects the arc conductor to the nozzle body.

10. A plasma arc welding torch comprising: a cathode extending along an axis of the welding torch; Arc conductor; Nozzle body; plasma gas duct; Shielding gas conduit; a cooling liquid return conduit; a plasma gas offset accessory including a first plasma gas conduit in fluid communication with the plasma gas conduit and a second plasma gas conduit in fluid communication with the first plasma gas conduit, wherein the second plasma gas conduit is radially offset outward from the first plasma gas conduit and extends in a proximal direction parallel to an axis of the torch away from the first plasma gas conduit; a shielding gas offset fitting comprising a first shielding gas conduit in fluid communication with the shielding gas conduit, and a second shielding gas conduit in fluid communication with the first shielding gas conduit, wherein the second shielding gas conduit is radially offset outward from the first shielding gas conduit and extends away from the first shielding gas conduit in the proximal direction parallel to an axis of the welding torch; a cooling liquid return offset fitting comprising a first cooling liquid return conduit in fluid communication with the cooling liquid return conduit, and a second cooling liquid return conduit in fluid communication with the first cooling liquid return conduit, wherein the second cooling liquid return conduit is radially offset outward from the first cooling liquid return conduit and extends away from the first cooling liquid return conduit in the proximal direction parallel to the axis of the torch; and a spring compression plug electrically connecting the arc conductor to the nozzle body; wherein the cathode comprises a first plurality of cooling liquid orifices, and the nozzle body comprises an internal cooling liquid passage for conveying cooling liquid toward a nozzle of the welding torch, wherein the welding torch further comprises: an internal isolator having a second plurality of cooling liquid orifices in fluid communication with the first plurality of cooling liquid orifices; and an outer separator radially offset from the inner separator to form an interstitial space through which the cooling liquid is delivered into the nozzle body, wherein a distal terminal end of the outer separator is radially offset from the inner separator such that the interstitial space extends to a distal terminal end of the outer separator, and the inner separator extends distally of the outer separator and the outer separator extends proximally of the inner separator, and wherein the inner separator and the outer separator electrically insulate the nozzle body from the cathode.

11. The plasma arc torch of claim 10, wherein: The internal cooling liquid passage is less than one inch in length and less than 0.1 inches in diameter.

12. The plasma arc torch of claim 10, wherein: The proximal terminal end of the inner isolator contacts an inner wall of the outer isolator, and the second plurality of cooling liquid orifices are located distal to the proximal terminal end of the inner isolator.

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