Plasma arc torch Number:7,145,098 from the United States Patent and Trademark Office (PTO) owispatent A plasma arc torch is provided that comprises a set of torch consumable components secured to a torch head, wherein a supply of cooling fluid flows coaxially through the torch to cool torch components and a supply of plasma gas and secondary gas flows through the torch to generate and stabilize a plasma stream for operations such as cutting workpieces. The torch consumable components, in part, comprise an electrode and a tip that include a variety of configurations for improved cooling, electrical contact, and attachment to adjacent torch components. Further, a consumables cartridge is provided for ease of use and replacement of the torch consumable components. Additionally, methods of operating the plasma arc torch at relatively high current levels are also provided by the present invention.<H Plasma, torch, Plasma, arc, torc, 7145098.html, Patent, pto, 7145098

Title: Plasma arc torch

Abstract: A plasma arc torch is provided that comprises a set of torch consumable components secured to a torch head, wherein a supply of cooling fluid flows coaxially through the torch to cool torch components and a supply of plasma gas and secondary gas flows through the torch to generate and stabilize a plasma stream for operations such as cutting workpieces. The torch consumable components, in part, comprise an electrode and a tip that include a variety of configurations for improved cooling, electrical contact, and attachment to adjacent torch components. Further, a consumables cartridge is provided for ease of use and replacement of the torch consumable components. Additionally, methods of operating the plasma arc torch at relatively high current levels are also provided by the present invention.

Patent Number: 7,145,098 Issued on 12/05/2006 to MacKenzie, et al.

Inventors: MacKenzie; Darrin H. (Windsor, VT), Conway; Christopher J. (Wilmot, NH), Kinerson; Kevin J. (Corinth, VT), Gugliotta; Mark (Concord, NH)
Assignee: Thermal Dynamics Corporation (West Lebanon, NH)

Appl. No.: 11/204,438

Filed: August 16, 2005

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
10409650	Apr., 2003	7019254

Current U.S. Class: 219/121.48 ; 219/121.49; 219/121.51; 219/75

Current International Class: B23K 10/00 (20060101)

Field of Search: 219/121.48,121.5,121.51,121.52,121.49,74,75 313/231.41,231.31

References Cited [Referenced By]

U.S. Patent Documents


3976852	August 1976	Van Horn
4156306	May 1979	Seidel et al.
4423304	December 1983	Bass et al.
5856647	January 1999	Luo
6403915	June 2002	Cook et al.

Primary Examiner: Paschall; Mark
Attorney, Agent or Firm: Harness, Dickey & Pierce P.L.C.

Parent Case Text

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation U.S. application Ser. No. 10/409,650, titled "Plasma Arc Torch," filed Apr. 7, 2003 now U.S. Pat. No. 7,019,254.

Claims

What is claimed is:

1. An assembly for use in a plasma arc torch comprising: a tip comprising a plurality of flutes; and a coolant guide comprising a plurality of radial tabs disposed within the flutes of the tip, wherein the radial tabs direct a flow of fluid through the plasma arc torch.

2. An assembly for use in a plasma arc torch comprising: a tip comprising a plurality of flutes; a coolant guide comprising a plurality of radial tabs disposed within the flutes of the tip; and a coolant seal disposed at a distal end portion of the coolant guide, wherein the assembly directs a flow of fluid and current through the plasma arc torch.

3. An assembly for use in a plasma arc torch comprising: an electrode comprising a plurality of ribs and flutes configured for the passage of fluid and electrical contact with an adjacent cathodic member; and a spacer disposed at a distal end portion of the electrode, wherein the assembly directs a flow of plasma gas and current through the plasma arc torch.

Description

FIELD OF THE INVENTION

The present invention relates generally to plasma arc torches and more particularly to devices and methods for automated, high current plasma arc torches.

BACKGROUND OF THE INVENTION

Plasma arc torches, also known as electric arc torches, are commonly used for cutting, marking, gouging, and welding metal workpieces by directing a high energy plasma stream consisting of ionized gas particles toward the workpiece. In a typical plasma arc torch, the gas to be ionized is supplied to a distal end of the torch and flows past an electrode before exiting through an orifice in the tip, or nozzle, of the plasma arc torch. The electrode has a relatively negative potential and operates as a cathode. Conversely, the torch tip constitutes a relatively positive potential and operates as an anode. Further, the electrode is in a spaced relationship with the tip, thereby creating a gap, at the distal end of the torch. In operation, a pilot arc is created in the gap between the electrode and the tip, which heats and subsequently ionizes the gas. Further, the ionized gas is blown out of the torch and appears as a plasma stream that extends distally off the tip. As the distal end of the torch is moved to a position close to the workpiece, the arc jumps or transfers from the torch tip to the workpiece because the impedance of the workpiece to ground is lower than the impedance of the torch tip to ground. Accordingly, the workpiece serves as the anode, and the plasma arc torch is operated in a "transferred arc" mode.

In automated plasma arc torch applications, the plasma arc torch operates at current levels between approximately 30 amps and 1,000 amps or more. At the higher current levels, the torch correspondingly operates at relatively high temperatures. Accordingly, torch components and consumable components must be properly cooled in order to prevent damage or malfunction and to increase the operating life and cutting accuracy of the plasma arc torch. To provide such cooling, high current plasma arc torches are generally water cooled, although additional cooling fluids may be employed, wherein coolant supply and return tubes are provided to cycle the flow of cooling fluid through the torch. Additionally, a variety of cooling and gas passageways are provided throughout various torch components for proper operation of the plasma arc torch. However, the flow of cooling fluids in plasma arc torches of the known art have been relatively limited due to the positioning and configuration of internal cooling passageways.

With automated plasma arc torches of the known art, concentricity of components within the torch, such as the electrode and the tip, or nozzle, is critical in order to maintain accuracy when cutting a workpiece. Further, the electrode and the tip are commonly known as consumable components, which must replaced after a certain period of operation due to wear and/or damage that occurs during operation. Accordingly, concentricity of such consumable components must be maintained throughout the many replacements that occur over the life of a plasma arc torch.

Additionally, when the consumable components are replaced, tools are often required for removal due to the type of connection between the consumable components and a torch head. For example, the consumable components may be threaded into the torch head and tightened with a wrench or other tool. As a result, the replacement of consumable components is often time consuming and cumbersome for a plasma arc torch operator. Moreover, each of the consumable components are typically replaced on an individual basis, rather than all at once, thereby making removal and installation of several different consumable components at different even more time consuming and cumbersome.

Accordingly, a need remains in the art for a plasma arc torch and associated methods that improve cutting efficiency and accuracy. A further need exists for such a plasma arc torch and methods that provide for relatively quick and efficient replacement of consumable components, (e.g., electrode, tip), disposed therein.

SUMMARY OF THE INVENTION

Generally, the present invention provides a plasma arc torch that comprises a set of torch consumable components secured to a torch head. The torch head comprises an anode body that is in electrical communication with the positive side of a power supply and a cathode that is in electrical communication with the negative side of the power supply. The cathode is further surrounded by a central insulator to insulate the cathode from the anode body, and similarly, the anode body is surrounded by an outer insulator to insulate the anode body from a housing, which encapsulates and protects the torch head and its components from the surrounding environment during operation. The torch head is further adjoined with a coolant supply tube, a plasma gas tube, a coolant return tube, and a secondary gas tube, wherein plasma gas and secondary gas are supplied and cooling fluid is supplied and returned for operation of the plasma arc torch. Furthermore, a negative lead connection is provided through the plasma gas tube or a liquid tube to the cathode, and a pilot signal connection is provided through the anode body to a torch cap.

The torch consumable components comprise an electrode, a tip, a spacer, a distal anode member, a central anode member, a baffle, a secondary cap, a shield cap, and a secondary spacer, which are housed by a cartridge body in one form of the present invention. The tip, central anode member, and distal anode member are anodic elements that comprise a portion of the positive side of the power supply, whereas the electrode is a cathodic element that comprises a portion of the negative side of the power supply. Accordingly, the spacer is disposed between the electrode and the tip and provides electrical separation between the anodic and cathodic sides of the power supply, in addition to certain gas distributing functions as described in greater detail below. The baffle is disposed between the distal anode member and the shield cap and provides for cooling fluid distribution during operation. The secondary cap is disposed distally from the tip and provides for secondary gas distribution, and the secondary spacer provides spacing between the tip and the secondary cap. Additionally, the shield cap surrounds the other consumable components and is secured to a torch head using a locking ring or other attachment member as described in greater detail below.

In another form of the present invention, the consumable components further comprise a coolant seal and guide disposed between the tip and the secondary cap to direct and control the flow of cooling fluid. The electrode is centrally disposed within the cartridge body and is in electrical contact with the cathode along an interior portion of the electrode. The electrode and cathode are configured such that a passageway is formed therebetween for the passage of a cooling fluid proximate, or through an adjacent vicinity of, the electrical contact. The electrode further defines a central cavity that is in fluid communication with the coolant tube such that the cathode and electrode, along with other torch components, are properly cooled during operation. Further, the cartridge body generally distributes cooling fluid, plasma gas, and secondary gas, while providing separation or dielectric between various torch components as described in the detailed description that follows. Moreover, the fluid (cooling, plasma, secondary) is distributed in a coaxial flow between various torch components, which increases the total amount of flow and cooling within the plasma arc torch.

As used herein, the term "coaxial" shall be construed to mean a flow that is annular and that flows in the same direction at any given radial location from the central longitudinal axis of the plasma arc torch. Additionally, the term "annular" shall be construed to mean a flow that is distributed circumferentially about the central longitudinal axis of the plasma arc torch (although not necessarily continuously). Therefore, coaxial flow is a flow that is distributed circumferentially about the central longitudinal axis of the torch and that is flowing in the same direction at any radial location from the central longitudinal axis. For example, a flow that crosses over the central longitudinal axis of the plasma arc torch such as that described in U.S. Pat. Nos. 5,396,043 and 5,653,896, incorporated herein by reference) is not a coaxial flow. Coaxial flow is shown and described in greater detail in the detailed description that follows.

The tip is disposed distally from the electrode and is separated therefrom by the spacer. Similarly, the secondary cap is disposed distally from the tip and is separated therefrom by the secondary spacer. The distal anode member is generally disposed around the tip and is in electrical contact with both the tip and the central anode member. The tip and distal anode member are configured such that a passageway is formed therebetween for the passage of a cooling fluid proximate, or through an adjacent vicinity of, the electrical contact. Further, the central anode member is in electrical contact with the anode body within the torch head for electrical continuity within the positive, or anodic side of the power supply. Additionally, the baffle is disposed around the distal anode member, and the shield cup is disposed around the baffle. Accordingly, passageways are formed between the cartridge body and the distal anode member, and between the distal anode member and the baffle for cooling fluid flow. Similarly, a passage is formed between the baffle and the shield cup for secondary gas flow.

In other forms, several electrode and tip configurations are provided that improve cooling, provide electrical continuity through the cathode and anode side of the power supply, respectively, and that provide efficient attachment of the electrode and tip to the plasma arc torch. Additionally, configurations for consumable cartridges are provided, wherein a single cartridge containing one or more consumable components is removed and replaced when the one or more consumable components require replacement, rather than replacing individual consumable components one at a time. Moreover, configurations for securing the torch head to adjacent components such as a positioning tube are also provided by other forms of the present invention.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a plasma arc torch constructed in accordance with the principles of the present invention;

FIG. 2 is an exploded perspective view of a plasma arc torch constructed in accordance with the principles of the present invention;

FIG. 3 is a longitudinal cross-sectional view, taken along line A--A of FIG. 1, of the plasma arc torch in accordance with the principles of the present invention;

FIG. 4 is an exploded longitudinal cross-sectional view of the plasma arc torch of FIG. 3 in accordance with the principles of the present invention;

FIG. 5 is an enlarged longitudinal cross-sectional view of a distal portion of the plasma arc torch of FIG. 3 in accordance with the principles of the present invention;

FIG. 6 is a longitudinal cross-sectional view of torch consumable components constructed in accordance with the principles of the present invention;

FIG. 7 is a cross-sectional view of anode members constructed in accordance with the principles of the present invention;

FIG. 8 is a perspective view of a cartridge body illustrating flexible tabs for a central anode member constructed in accordance with the principles of the present invention;

FIG. 9a is a longitudinal cross-sectional view of a plasma arc torch illustrating coaxial flow in accordance with the principles of the present invention;

FIG. 9b is a lateral cross-sectional view of a plasma arc torch illustrating coaxial flow in accordance with the principles of the present invention;

FIG. 10 is a perspective view of a torch cap of a plasma arc torch and constructed in accordance with the principles of the present invention;

FIG. 11 is a cutaway perspective view of a plasma arc torch illustrating fluid passageways in accordance with the principles of the present invention;

FIG. 12a is a cutaway perspective view of an electrode constructed in accordance with the principles of the present invention;

FIG. 12b is a perspective cutaway exploded view of a cathode within a torch head and an electrode constructed in accordance with the principles of the present invention;

FIG. 12c is a cross-sectional view of an electrode disposed around a cathode in accordance with the principles of the present invention;

FIG. 12d is a lateral cross-sectional view, taken along line B--B of FIG. 12c, illustrating adjacent perimeter surfaces between an electrode and a cathode in accordance with the principles of the present invention;

FIG. 13a is a perspective view of a second embodiment of an electrode constructed in accordance with the principles of the present invention;

FIG. 13b is a longitudinal cross-sectional view of the electrode of the second embodiment secured within a plasma arc torch in accordance with the principles of the present invention;

FIG. 13c is a lateral cross-sectional view of the electrode of the second embodiment secured within a plasma arc torch in accordance with the principles of the present invention;

FIG. 14a is a perspective view of a third embodiment of an electrode constructed in accordance with the principles of the present invention;

FIG. 14b is a longitudinal cross-sectional view of the third electrode embodiment secured within a plasma arc torch in accordance with the principles of the present invention;

FIG. 15 is a longitudinal cross-sectional view of a fourth embodiment of an electrode secured within a plasma arc torch and constructed in accordance with the principles of the present invention;

FIG. 16 is a longitudinal cross-sectional view of a fifth embodiment of an electrode secured within a plasma arc torch and constructed in accordance with the principles of the present invention;

FIG. 17a is a longitudinal cross-sectional view of a fluid passageway formed in a cathode adjacent electrical contact with an electrode and constructed in accordance with the teachings of the present invention;

FIG. 17b is a lateral cross-sectional view, taken along line C--C of FIG. 17a, of the cathode and electrode in accordance with the principles of the present invention;

FIG. 17c is a longitudinal cross-sectional view of a fluid passageway formed by a third element between a cathode and an electrode in accordance with the principles of the present invention;

FIG. 17d is a longitudinal cross-sectional view of a fluid passageway formed by a helical flute between a cathode and an electrode in accordance with the principles of the present invention;

FIG. 17e is a longitudinal cross-sectional view of a fluid passageway formed through a cathode and an electrode in accordance with the principles of the present invention;

FIG. 17f is a longitudinal cross-sectional view of a fluid passageway formed through an electrode in accordance with the principles of the present invention;

FIG. 18 is a longitudinal cross-sectional view of an electrode holder constructed in accordance with the teachings of the present invention;

FIG. 19 is a perspective view of a tip constructed in accordance with the principles of the present invention;

FIG. 20 is a side view of the tip of FIG. 19 in accordance with the principles of the present invention;

FIG. 21 is a longitudinal cross-sectional view of the tip, taken along line D--D of FIG. 20, in accordance with the principles of the present invention;

FIG. 22 is a top view of the tip of FIG. 19 in accordance with the principles of the present invention;

FIG. 23 is a cross-sectional view of the tip disposed adjacent a distal anode member in accordance with the principles of the present invention;

FIG. 24a is a cross-sectional view of a fluid passageway formed in a tip adjacent electrical contact with the distal anode member in accordance with the principles of the present invention;

FIG. 24b is a cross-sectional view, taken along line E--E of FIG. 24a, of the tip and distal anode member in accordance with the principles of the present invention;

FIG. 24c is a cross-sectional view of a fluid passageway formed by a third member disposed between a tip and a distal anode member in accordance with the principles of the present invention;

FIG. 24d is a cross-sectional view of a fluid passageway formed between by a helical flute between a tip and a distal anode member in accordance with the principles of the present invention;

FIG. 25a is a perspective view of a secondary cap constructed in accordance with the principles of the present invention;

FIG. 25b is a top view of a secondary cap constructed in accordance with the principles of the present invention;

FIG. 26a is a longitudinal side cross-sectional view of secondary gas bleed passageways constructed in accordance with the principles of the present invention;

FIG. 26b is a top view of a shield cap comprising secondary gas bleed passageways and constructed in accordance with the principles of the present invention;

FIG. 26c is a longitudinal side cross-sectional view of an alternate torch embodiment for bleeding secondary gas and constructed in accordance with the principles of the present invention;

FIG. 27a is a perspective view of a secondary cap spacer constructed in accordance with the principles of the present invention;

FIG. 27b is a side view of the secondary spacer constructed in accordance with the principles of the present invention;

FIG. 28a is a perspective view of a consumables cartridge constructed in accordance with the principles of the present invention;

FIG. 28b is a longitudinal cross-sectional view of the consumables cartridge, taken along line E--E of FIG. 28a, in accordance with the principles of the present invention;

FIG. 29 is a longitudinal cross-sectional view of a second embodiment of a consumables cartridge constructed in accordance with the principles of the present invention;

FIG. 30 is a longitudinal cross-sectional view of a stepped cartridge attachment illustrating cooling fluid passageways and constructed in accordance with the principles of the present invention;

FIG. 31 is a longitudinal cross-sectional view of a stepped cartridge attachment illustrating gas passageways and constructed in accordance with the principles of the present invention;

FIG. 32a is a longitudinal cross-sectional view of a face seal cartridge attachment illustrating cooling fluid passageways and constructed in accordance with the principles of the present invention;

FIG. 32b is a longitudinal cross-sectional view of a face seal cartridge attachment illustrating gas passageways and constructed in accordance with the principles of the present invention;

FIG. 33a is a longitudinal cross-sectional view of a straight cartridge attachment illustrating cooling fluid passageways and constructed in accordance with the principles of the present invention;

FIG. 33b is a longitudinal cross-sectional view of a straight cartridge attachment illustrating gas passageways and constructed in accordance with the principles of the present invention;

FIG. 34a is an enlarged longitudinal cross-sectional view of a ball-lock mechanism connected and constructed in accordance with the principles of the present invention;

FIG. 34a is an enlarged longitudinal cross-sectional view of a ball-lock mechanism disconnected and constructed in accordance with the principles of the present invention;

FIG. 35a is a longitudinal cross-sectional view of a torch head having alignment geometry and constructed in accordance with the principles of the present invention;

FIG. 35b is a top view of a torch head having alignment geometry and constructed in accordance with the principles of the present invention;

FIG. 36 is a longitudinal cross-sectional view of a second plasma arc torch embodiment constructed in accordance with the teachings of the present invention;

FIG. 37 is a longitudinal cross-sectional view of a torch head of the second plasma arc torch embodiment in accordance with the principles of the present invention;

FIG. 38 is a longitudinal cross-sectional view of consumable components of the second plasma arc torch embodiment in accordance with the principles of the present invention;

FIG. 39a is a perspective view of a cartridge body constructed in accordance with the teachings of the present invention;

FIG. 39b is a proximal perspective view of a cartridge body constructed in accordance with the teachings of the present invention;

FIG. 39c is a top view of a cartridge body constructed in accordance with the teachings of the present invention;

FIG. 39c is a bottom view of a cartridge body constructed in accordance with the teachings of the present invention;

FIG. 40 is a perspective view of a central anode member constructed in accordance with the teachings of the present invention;

FIG. 41 is a perspective view of a distal anode member constructed in accordance with the teachings of the present invention;

FIG. 42 is an exploded perspective view of a tip, a tip guide, and a tip seal constructed in accordance with the teachings of the present invention;

FIG. 43 is a side view of a tip assembly constructed in accordance with the teachings of the present invention;

FIG. 44 is a longitudinal cross-sectional view of a plasma arc torch illustrating the cooling fluid flow in accordance with the principles of the present invention;

FIG. 45 is a longitudinal cross-sectional view of a plasma arc torch illustrating the plasma gas flow in accordance with the principles of the present invention;

FIG. 46 is a longitudinal cross-sectional view of a plasma arc torch illustrating the secondary gas flow in accordance with the principles of the present invention;

FIG. 47a is a longitudinal cross-sectional view of a consumables cartridge constructed in accordance with the teachings of the present invention;

FIG. 47b is a longitudinal cross-sectional view of a second embodiment of a consumables cartridge constructed in accordance with the teachings of the present invention;

FIG. 47c is a longitudinal cross-sectional view of a third embodiment of a consumables cartridge constructed in accordance with the teachings of the present invention;

FIG. 47d is a longitudinal cross-sectional view of a fourth embodiment of a consumables cartridge constructed in accordance with the teachings of the present invention;

FIG. 47e is a longitudinal cross-sectional view of a fifth embodiment of a consumables cartridge constructed in accordance with the teachings of the present invention;

FIG. 47f is a longitudinal cross-sectional view of a sixth embodiment of a consumables cartridge constructed in accordance with the teachings of the present invention;

FIG. 48a is a longitudinal cross-sectional view of a consumables assembly constructed in accordance with the teachings of the present invention;

FIG. 48b is a longitudinal cross-sectional view of a second embodiment of a consumables assembly in accordance with the principles of the present invention;

FIG. 48c is a longitudinal cross-sectional view of a third embodiment of a consumables assembly in accordance with the principles of the present invention;

FIG. 48d is a longitudinal cross-sectional view of a fourth embodiment of a consumables assembly in accordance with the principles of the present invention;

FIG. 48e is a longitudinal cross-sectional view of a fifth embodiment of a consumables assembly in accordance with the principles of the present invention;

FIG. 48f is a longitudinal cross-sectional view of a sixth embodiment of a consumables assembly in accordance with the principles of the present invention;

FIG. 48g is a longitudinal cross-sectional view of a seventh embodiment of a consumables assembly in accordance with the principles of the present invention;

FIG. 49 is an exploded longitudinal cross-sectional view of torch head connections constructed in accordance with the teachings of the present invention;

FIG. 50 is a longitudinal cross-sectional view of another plasma arc torch embodiment constructed in accordance with the teachings of the present invention; and

FIG. 51 is a schematic view illustrating a plasma arc torch employed within a plasma arc torch cutting system in accordance with the various embodiments of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

Referring to the drawings, a plasma arc torch according to the present invention is illustrated and indicated by reference numeral 10 in FIG. 1 through FIG. 6. The plasma arc torch 10 generally comprises a torch head 12 disposed at a proximal end 14 of the plasma arc torch 10 and a plurality of consumable components 16 secured to the torch head 12 and disposed at a distal end 18 of the plasma arc torch 10 as shown.

As used herein, a plasma arc torch should be construed by those skilled in the art to be an apparatus that generates or uses plasma for cutting, welding, spraying, gouging, or marking operations, among others, whether manual or automated. Accordingly, the specific reference to plasma arc cutting torches or plasma arc torches should not be construed as limiting the scope of the present invention. Furthermore, the specific reference to providing gas to a plasma arc torch should not be construed as limiting the scope of the present invention, such that other fluids, e.g. liquids, may also be provided to the plasma arc torch in accordance with the teachings of the present invention. Additionally, proximal direction or proximally is the direction towards the torch head 12 from the consumable components 16 as depicted by arrow A', and distal direction or distally is the direction towards the consumable components 16 from the torch head 12 as depicted by arrow B'.

Torch Head

Referring more specifically to FIG. 5, the torch head 12 includes an anode body 20 that is in electrical communication with the positive side of a power supply (not shown), and a cathode 22 that is in electrical communication with the negative side of the power supply. The cathode 22 is further surrounded by a central insulator 24 to insulate the cathode 22 from the anode body 20, and similarly, the anode body 20 is surrounded by an outer insulator 26 to insulate the anode body 20 from a housing 28, which encapsulates and protects the torch head 12 and its components from the surrounding environment during operation. The torch head 12 is further adjoined with a coolant supply tube 30, a plasma gas tube 32, a coolant return tube 34, and a secondary gas tube 35 (shown in their entirety in FIGS. 1 and 2), wherein plasma gas and secondary gas are supplied to and cooling fluid is supplied to and returned from the plasma arc torch 10 during operation as described in greater detail below.

The cathode 22 preferably defines a cylindrical tube having a central bore 36 that is in fluid communication with the coolant supply tube 30 at a proximal portion 38 of the torch head 12. The central bore 36 is also in fluid communication with a cathode cap 40 and a coolant tube 42 disposed at a distal portion 44 of the torch head 12. Generally, the coolant tube 42 serves to distribute the cooling fluid and the cathode cap 40 protects the distal end of the cathode 22 from damage during replacement of the consumable components 16 or other repairs. As further shown, the cathode 22 comprises an internal annular ring 46 that engages a proximal groove 48 formed in the cathode cap 40. As further shown, a flexible collar 49 formed on the cathode cap 40 engages the annular ring 46 such that the cathode cap 40 is properly secured within the cathode 22. To secure the coolant tube 42, the cathode cap 40 defines an internal shoulder 50 against which an annular ring 52 of the coolant tube 42 abuts. Further, the coolant tube 42 defines an o-ring groove 54 that houses an o-ring 56 to seal and retain the interface between the cathode cap 40 and the coolant tube 42. Preferably, the coolant tube 42 is formed of a durable material such as stainless steel, and the cathode cap 40 is insulative and is preferably formed of a material such as Torlon.RTM. or other material known in the art that is also capable of operating at relatively high temperatures (For example, approximately 250.degree. C. to approximately 350.degree. C.).

The central insulator 24 preferably defines a cylindrical tube having an internal bore 60 that houses the cathode 22 as shown. The cathode 22 defines a proximal external shoulder 62 that abuts a proximal internal shoulder 64 of the central insulator 24 to position of the cathode 22 along the central longitudinal axis X of the plasma arc torch 10. Further, the cathode 22 comprises an external o-ring groove 65 that houses an o-ring 66 to seal the interface between the cathode 22 and the central insulator 24. The central insulator 24 is further disposed within the anode body 20 as shown along a central portion 68 and also engages a torch cap 70 that accommodates the coolant supply tube 30, the plasma gas tube 32, and the coolant return tube 34.

Electrical continuity for electric signals such as a pilot return is provided through a contact 72 disposed between the torch cap 70 and the anode body 20. The contact 72 comprises a proximal flange 74 that abuts a recessed shoulder 76 formed in the torch cap 70 and a distal end 78 that engages the anode body 20 as shown. Preferably, the contact 72 is threaded into the anode body 20, however, other attachment methods such as a press fit or soldering may also be used while remaining within the scope of the present invention. Additionally, a distal annular wall 80 of the torch cap 70 abuts an o-ring 82 disposed within an o-ring groove 84 within the outer insulator 26 to seal the interface between the torch cap 70 and the outer insulator 26. Similarly, a distal internal wall 86 of the housing 28 abuts an o-ring 88 disposed within an o-ring groove 90 of the consumable components 16 to seal an interface between the housing 28 and the consumable components 16. Additional o-ring grooves 92 with corresponding o-rings (not shown) are provided between a plurality of interfaces as shown to seal the fluid (plasma gas, secondary gas, cooling fluid) passageways and are not described in further detail herein for purposes of clarity.

Alternately, electrical continuity for the pilot return or other electrical signals may be provided directly through an interface between the torch cap 70 and the anode body 20 using detents engaging a shoulder as shown and described in U.S. Pat. No. 6,163,008, which is commonly assigned with the present application and the contents of which are incorporated herein by reference. The detents may be incorporated on the torch cap 70 or the anode body 20 with a corresponding shoulder and cap on the anode body 20 or torch cap 70, respectively. Further, the detents provide a connection that is relatively simple and easy to engage and disengage. Similarly, other components within the plasma arc torch 10 may also employ the detents and shoulder for their respective connections while remaining within the scope of the present invention.

Consumable Components

The consumable components 16, which are shown in greater detail in FIG. 6, comprise an electrode 100, a tip 102, and a spacer 104 disposed between the electrode 100 and the tip 102 as shown. The spacer 104 provides electrical separation between the cathodic electrode 100 and the anodic tip 102, and further provides certain gas distributing functions as described in greater detail below. The consumable components 16 further comprise a cartridge body 106, which generally houses and positions the other consumable components 16. The cartridge body 106 also distributes plasma gas, secondary gas, and cooling fluid during operation of the plasma arc torch 10, which is described in greater detail below. Additionally, the consumable components 16 comprise a distal anode member 108 and a central anode member 109 to form a portion of the anodic side of the power supply by providing electrical continuity to the tip 102. A baffle 110 is also shown disposed between the distal anode member 108 and a shield cap 114, which forms fluid passageways for the flow of a cooling fluid as described in greater detail below. Further, the consumable components 16 comprise a secondary cap 112 for the distribution of the secondary gas and a secondary spacer 116 that separates the secondary cap 112 from the tip 102. A locking ring 117 is shown disposed around the proximal end portion of the consumable components 16, which is used to secure the consumable components 16 to the torch head 12 (not shown).

The electrode 100 is centrally disposed within the cartridge body 106 and is in electrical contact with the cathode 22 (FIG. 5) along an interior portion 118 of the electrode 100 as described in greater detail below. The electrode 100 further defines a distal cavity 120 that is in fluid communication with the coolant tube 42 (FIG. 5) and an external shoulder 122 that abuts the spacer 104 for proper positioning along the central longitudinal axis X of the plasma arc torch 10. The cartridge body 106 further comprises an internal annular ring 124 that abuts a proximal end 126 of the electrode 100 for proper positioning of the electrode 100 along the central longitudinal axis X of the plasma arc torch 10. Additionally, the connection between the cartridge body 106 and the cathode 22 may employ the detents and shoulder as previously described while remaining within the scope of the present invention. In addition to positioning the various consumable components 16, the cartridge body 106 also separates anodic member (e.g., central anode member 109) from cathodic members (e.g., electrode 100). Accordingly, the cartridge body 106 is an insulative material such as PEEK.RTM. or other similar material commonly known in the art that is further capable of operating at relatively high temperatures.

For the distribution of cooling fluid as described in greater detail below, the cartridge body 106 defines an upper chamber 128 and a plurality of passageways 130 that extend through the cartridge body 106 and into an inner cooling chamber 132 formed between the cartridge body 106 and the distal anode member 108. Preferably, the passageways 130 (shown dashed) are angled radially outward in the distal direction from the upper chamber 128 (shown dashed) to reduce any amount of dielectric creep that may occur between the electrode 100 and the distal anode member 108. Additionally, outer axial passageways 133 are formed in the cartridge body 106 that provide for a return of the cooling fluid, which is further described below. For the distribution of plasma gas, the cartridge body 106 defines a plurality of distal axial passageways 134 that extend from a proximal face 136 of the cartridge body 106 to a distal end 138 thereof, which are in fluid communication with the plasma gas tube 32 (not shown) and passageways formed in the tip 102 as described in greater detail below. Additionally, a plurality of proximal axial passageways 140 are formed through the cartridge body 106 that extend from a recessed proximal face 142 to a distal outer face 144 for the distribution of a secondary gas, which is also described in greater detail below. Near the distal end of the consumables cartridge 16, an outer fluid passage 148 is formed between the distal anode member 108 and the baffle 110 for the return of cooling fluid as described in greater detail below. Accordingly, the cartridge body 106 performs both cooling fluid distribution functions in addition to plasma gas and secondary gas distribution functions.

As shown in FIGS. 5 and 6, the distal anode member 108 is disposed between the cartridge body 106 and the baffle 110 and is in electrical contact with the tip 102 at a distal portion and with the central anode member 109 at a proximal portion. Further, the central anode member 109 is in electrical contact with a distal portion of the anode body 20. Preferably, a canted coil spring (not shown) is disposed within a groove 146 to provide electrical contact between the central anode member 109 and the anode body 20. Alternately, electrical continuity for the pilot return or other electrical signals may be provided directly through an interface between the central anode member 109 and the anode body 20 using detents engaging a shoulder as shown and described in U.S. Pat. No. 6,163,008, which is commonly assigned with the present application and the contents of which are incorporated herein by reference. The detents may be incorporated on the central anode member 109 or the anode body 20 with a corresponding shoulder and cap on the anode body 20 or central anode member 109, respectively. Accordingly, the anode body 20, the distal anode member 108, the central anode member 109, and the tip 102 form the anode, or positive, potential for the plasma arc torch 10.

The detents are illustrated in greater detail in FIGS. 7 and 8, wherein the central anode member 109 is preferably secured to the cartridge body 106 using detents 260 as shown. (Certain portions of the plasma arc torch 10 and the cartridge body 106 are omitted for purposes of clarity). The detents 260 extend radially inward to engage a shoulder 262 formed at the proximal end of the cartridge body 106 that extends radially outward as shown. Alternately, the detents 260 may extend radially outward while the shoulder 262 extends radially inward in another form of the present invention. Additionally, the detents 260 are formed in flexible tabs 264 of the central anode member 109 as shown, wherein the tabs 264 provide additionally flexibility for assembly of the central anode member 109 to the cartridge body 106.

Referring again to FIG. 6, the shield cap 114 surrounds the baffle 110 as shown, wherein a secondary gas passage 150 is formed therebetween. Generally, the secondary gas flows from the proximal axial passageways 140 formed in the cartridge body 106 into the secondary gas passage 150 and through the secondary cap 112, as described in greater detail below, to stabilize the plasma stream exiting the secondary cap 112 in operation. The shield cap 114 further positions the secondary cap 112, wherein the secondary cap 112 defines an annular shoulder 152 that engages a conical interior surface 154 of the shield cap 114. Alternately, the shield cap 114 may define a rounded corner (not shown) rather than a conical surface to engage the annular shoulder 152 for an improved fit. Similarly, the secondary cap 112 may alternately define a rounded corner that engages the conical interior surface 154 of the shield cap 114.

The secondary spacer 116 spaces and insulates the secondary cap 112 from the tip 102. Preferably, the secondary spacer 116 comprises a proximal face 156 that abuts an annular shoulder 158 of the tip 102 and a distal face 160 and shoulder 162 that abut an internal shoulder 164 of the secondary cap 112. As further shown, a secondary gas chamber 167 is formed between the tip 102 and the secondary cap 112, wherein the secondary gas is distributed to stabilize the plasma stream, as described in greater detail below. The secondary cap 112 further comprises a central exit orifice 168 through which the plasma stream exits and a recessed face 170 that contributes to controlling the plasma stream. Additionally, bleed passageways 171 may be provided through the secondary cap 112, which are shown as axial holes although other configurations may be employed as described in greater detail below, to bleed off a portion of the secondary gas for additional cooling during operation.

The tip 102 is electrically separated from the electrode 100 by the spacer 104, which results in a plasma chamber 172 being formed between the electrode 100 and the tip 102. The tip 102 further comprises a central exit orifice 174, through which a plasma stream exits during operation of the plasma arc torch 10 as the plasma gas is ionized within the plasma chamber 172. Accordingly, the plasma gas enters the tip 102 through an annular ring 176 and swirl holes 178, which are described in greater detail below, formed through an interior wall 180 of the tip 102 as shown.

As further shown, the locking ring 117 secures the consumable components 16 to the torch head 12 when the plasma arc torch 10 is fully assembled. The locking ring 117 forms an internal shoulder 182 that engages an annular ring 184 formed on the cartridge body 106 and is preferably secured to the torch head 12 through a threaded connection. Alternately, the torch head 12 may be secured to the torch consumable components 16 using a dual pitch locking connector as shown and described in copending application Ser. No. 10/035,534 filed Nov. 9, 2001, which is commonly assigned with the present application and the contents of which are incorporated herein by reference.

Cooling Fluid Flow

Referring again to FIGS. 5 and 6, in operation, the cooling fluid flows distally through the central bore 36 of the cathode 22, through the coolant tube 42, and into the distal cavity 120 of the electrode 100. The cooling fluid then flows proximally through the proximal cavity 118 of the electrode 100 to provide cooling to the electrode 100 and the cathode 22 that are operated at relatively high currents and temperatures. The cooling fluid continues to flow proximally to the radial passageways 130 in the cartridge body 106, wherein the cooling fluid then flows through the passageways 130 and into the inner cooling chamber 132. The cooling fluid then flows distally towards the tip 102, which also operates at relatively high temperatures, in order to provide cooling to the tip 102. As the cooling fluid reaches the distal portion of the distal anode member 108, the cooling fluid reverses direction again and flows proximally through the outer fluid passage 148 and then through the outer axial passageways 133 in the cartridge body 106. The cooling fluid then flows proximally through recessed walls 190 (shown dashed) and axial passageways 192 (shown dashed) formed in the anode body 20. Once the cooling fluid reaches a proximal shoulder 193 of the anode body 20, the fluid flows through the coolant return tube 34 and is recirculated for distribution back through the coolant supply tube 30.

As a result, the cooling fluid flow is "coaxial," which is illustrated in FIGS. 9a and 9b, wherein the flow of the cooling fluid is shown by the heavy dark arrows. As shown, the cooling fluid generally flows distally, then proximally, then distally again, and then proximally to return the cooling fluid for recirculation. Additionally, the cooling fluid flows annularly, which is best shown in FIG. 9b, wherein the flow is generally annular about the central longitudinal axis X of the plasma arc torch 10. As further shown, the flow is in the same direction (i.e. proximal or distal) at each radial location K, L, M, and N. At radial location K, the cooling fluid is flowing distally; at radial location L, the cooling fluid is flowing proximally; at radial location M, the cooling fluid is flowing distally, and at radial location N, the cooling fluid is flowing proximally again. Also note that the cooling fluid does not flow radially to cross the central longitudinal axis X of the plasma arc torch 10 for fluid return. Rather, the cooling fluid flows coaxially and progressively outwardly to cool components of the plasma arc torch 10 and to return for recirculation.

Therefore, as used herein, the term coaxial flow shall be construed to mean a flow that is annular and that flows in the same direction at any given radial location from the central longitudinal axis X of the plasma arc torch 10. Additionally, the term "annular" shall be construed to mean a flow that is distributed circumferentially about the central longitudinal axis of the plasma arc torch. Therefore, coaxial flow is a flow that is distributed circumferentially about the central longitudinal axis of the torch and that is flowing in the same direction at any radial location from the central longitudinal axis. Accordingly, a coaxial cooling flow is provided by the present invention to efficiently cool components throughout the plasma arc torch 10.

Plasma Gas Flow

Referring to FIGS. 5 and 6, the plasma gas generally flows distally from the plasma gas tube 32, through an axial passage 194 (shown dashed) in the torch cap 70, and into a central cavity 196 formed in the anode body 20. The plasma gas then flows distally through axial passageways 198 formed through an internal distal shoulder 200 of the anode body 20 and into the distal axial passageways 134 formed in the cartridge body 106. The plasma gas then enters the plasma chamber 172 through passageways in the tip 102, which are described in greater detail below, to form a plasma stream as the plasma gas is ionized by the pilot arc.

Secondary Gas Flow

Referring to FIGS. 5, 10, and 11, the secondary gas generally flows distally from the secondary gas tube 35 (shown in FIGS. 1 and 2) and through an axial passage 202 formed between an outer wall 204 of the torch cap 70 and the housing 28. The secondary gas then continues to flow distally through axial passageways 206 formed through an annular extension 208 of the outer insulator 26 and into the proximal axial passageways 140 of the cartridge body 106. The secondary gas then enters the secondary gas passage 150 and flows distally between the baffle 110 and the shield cap 114, through the distal secondary gas passage 209. Finally, the secondary gas enters the secondary gas plenum 167 through passageways formed in the secondary cap 112, which are described in greater detail below, to stabilize the plasma stream that exits through the central exit orifice 174 of the tip 102.

Operation

In operation, the cathode or negative potential is carried by the cathode 22 and the electrode 100. The anode or positive potential is carried by the anode body 20, the distal anode member 108, the central anode member 109, and the tip 102. Therefore, when electric power is applied to the plasma arc torch 10, a pilot arc is generated in the gap formed between the electrode 100 and the tip 102, within the plasma chamber 172. As the plasma gas enters the plasma chamber 172, the plasma gas is ionized by the pilot arc, which cause a plasma stream to form within the plasma chamber 172 and flow distally through the central exit orifice 174 of the tip 102. Additionally, the secondary gas flows into the secondary gas plenum 167 and stabilizes the plasma stream upon exiting the central exit orifice 174 of the tip 102. As a result, a highly uniform and stable plasma stream exits the central exit orifice 168 of the secondary cap 112 for high current, high tolerance cutting operations.

Electrode Embodiments

Referring now to FIGS. 12a through 18, the electrode 100 may comprise a variety of configurations for proper cooling, electrical contact with the cathode 22, and attachment to the cartridge body 106. In the embodiments shown and described herein, cooling of the electrode 100 is provided proximate, or through an adjacent vicinity of, the electrical contact between the electrode 100 and the cathode 22, which is further defined in the description that follows.

In a first embodiment as shown in FIGS. 12a through 12d, the electrode 100a defines flutes 220 and raised ribs 222. The flutes 220 form a fluid passageway between the electrode 100a and the cathode 22a (best shown in FIG. 12d) for cooling proximate the electrical contact between the electrode 100a and the cathode 22a. More specifically, the flutes 220 produce a relatively high velocity flow proximate the interface between the electrode 100a and the cathode 22a, where cooling is critical. Additionally, the raised ribs 222 are in electrical contact with an outer wall 224 of the cathode 22a, which provides electrical continuity between the cathodic members (i.e. cathode, electrode) of the plasma arc torch 10. Preferably, the outer wall 224 defines a plurality of axial tabs 226 as shown in FIG. 12b such that the cathode cap 40 and the coolant tube 42 may be more easily assembled within the cathode 22a.

Referring specifically to FIG. 12d, which is a view showing the lateral interface between the electrode 100a and the cathode 22a, the electrode 100a defines a perimeter surface 225 and the cathode 22a similarly defines a perimeter surface 227. The perimeter surfaces 225 and 227 are thus defined by taking a section cut along a lateral plane through the interface between the electrode 100a and the cathode 22a or other cathodic element. (The surfaces are shown in FIG. 12d with a slight gap for illustration purposes only, and the perimeter surface 225 of the electrode 100a physically contacts the perimeter surface 227 of the cathode 22a during operation). Accordingly, the perimeter surface 225 of the electrode 100a is adjacent the perimeter surface 227 of the cathode 22a, wherein the adjacent perimeter surfaces 225 and 227 provide both the electrical contact and the passage of a cooling fluid. Thus, a novel aspect of the present invention is providing both the electrical contact and the passage of the cooling fluid through the adjacent perimeter surfaces. As a result, both cooling and electrical contact are provided proximate, or in an adjacent vicinity to, one another, which provides for more efficient operation of the plasma arc torch 10.

As shown in FIGS. 13a through 13c, a second embodiment of the electrode indicated as 100b may alternately define axial passageways 230 rather than the flutes 220, wherein the axial passageways 230 produce the relatively high velocity flow of the cooling fluid that flows proximally therethrough. Accordingly, the cooling fluid flows proximally through the axial passageways 230 to cool the interface between the electrode 100b and the cathode 22b. For electrical contact, an internal wall 228 is formed within the electrode 100b that makes contact with the outer wall 224 of the cathode 22b.

Referring to FIG. 13c, which is a lateral view through the interface between the electrode 100b and the cathode 22b, the electrode 100b defines a perimeter surface 229 and the cathode 22b defines a perimeter surface 331. Accordingly, the perimeter surface 229 of the electrode 100b is adjacent the perimeter surface 331 of the cathode 22b. (The surfaces are shown in FIG. 13c with a slight gap for illustration purposes only, and the perimeter surface 229 of the electrode 100b physically contacts the perimeter surface 331 of the cathode 22b during operation). Although the adjacent perimeter surfaces 229 and 331 provide only electrical contact in this form of the present invention, the passage of cooling fluid through axial passageways 230 is proximate, or through an adjacent vicinity of the electrical contact as shown such that effective cooling of the interface between the electrode 100b and the cathode 22b is achieved. For example, the distance P between the axial passageways 230 and the perimeter surface 331 of the cathode 22c is approximately 0.050 inches to define an adjacent vicinity in one form of the present invention. However, other distances may be employed so long as the electrical interface between the electrode 100c and the cathode 22c is properly cooled by the cooling fluid flowing through the fluid passageways. Therefore, the terms "proximate" or "adjacent vicinity" as used herein with respect to cooling the interface between the electrode 100 and the cathode 22b shall be construed to mean along or within a close distance to the electrical contact such that effective cooling is achieved. Accordingly, the adjacent perimeter surfaces throughout the remaining electrode embodiments shall not be illustrated for purposes of clarity.

In a third embodiment of the electrode indicated as 100c in FIGS. 14a and 14b, the electrode 100c defines radial passageways 232 and axial slots 234 to provide cooling between the electrode 100c and the cathode 22c. The cooling fluid generally flows proximally to the radial passageways 232 and then proximally to the axial slots 234, wherein the cooling fluid exits the interface between the electrode 100c and the cathode 22c and proceeds through the passageways 130 as previously described. For electrical contact, an internal wall 236 is similarly formed within the electrode 100c that makes contact with the outer wall 224 of the cathode 22c. Accordingly, a perimeter surface of the electrode 100c is adjacent a perimeter surface of the cathode 22c to form a fluid passageway for cooling proximate the electrical contact.

Referring now to FIG. 15, a fourth embodiment of the electrode indicated as 100d comprises an internal undercut 240 to provide additional cooling of the electrode 100d and the interface between the electrode 100d and the cathode 22d. Additionally, the cathode 22d defines radial passageways 242 that provide a return path for the cooling fluid to flow proximally between the coolant tube 42d and the cathode 22d as shown. Therefore, the cooling fluid flows distally through the coolant tube 42d, proximally through the internal under cut 240, then radially inward through the radial passageways 242, and then proximally between the coolant tube 42d and the cathode 22d for recirculation. Further, electrical contact is provided between an internal wall 244 of the electrode 100d and the outer wall 224 of the cathode 22d. Accordingly, a fluid passageway is formed such that cooling is provided proximate the electrical contact between the electrode 100d and the cathode 22d. Alternately, the electrode 100d may comprise an external undercut rather than an internal undercut as described herein while remaining within the scope of the present invention.

As shown in FIG. 16, a fifth embodiment of the electrode indicated as 100e is preferably secured within the cathode 22e using detents 250 as shown and described in U.S. Pat. No. 6,163,008, which is commonly assigned with the present application and the contents of which are incorporated herein by reference. In the illustrated embodiment, the detents 250 engage a shoulder 252 of a cap 254 secured to a distal end of the cathode 22e as shown. Similarly, the tip 102 as shown may also be secured to the cartridge body 106 using detents 256, wherein the detents 256 engage a shoulder 258 of an insulator element 260 secured to a distal end of the cartridge body 106 (not shown). As shown, the detents 250 and 256 extend radially outward to engage the shoulders 252 and 258, respectively. However, the detents 250 and 256 may alternately extend radially inward to engage shoulders (not shown) that extend radially outward in another form of the present invention.

Referring now to FIGS. 17a through 17f, additional embodiments of the electrode 100 and the cathode 22 are illustrated, wherein cooling is provided proximate or through an adjacent vicinity of the electrical contact between the electrode 100 and the cathode 22 and the cooling fluid flows through at least one fluid passageway formed through the electrode 100 and/or the cathode 10. In each of the following embodiments, the fluid passageway may be formed in either the electrode 100 or the cathode 22, depending on whether the cathode 22 is disposed within the electrode 100 or whether the electrode 100 is disposed around the cathode 22. Accordingly, illustration and discussion of fluid passageways through the electrode 100 shall also be construed to mean fluid passageways through the cathode 22 in alternate forms of the present invention and vice versa.

FIGS. 17a and 17b illustrate an electrode 100f defining an extended inner wall 251 and a cathode 22f defining at least one spot recess 253. Accordingly, the cooling fluid flows distally through the cathode 22f and then proximally through the spot recesses 253. Since the spot recesses 253 are not continuous around the perimeter of the cathode 22f, the extended inner wall 251 of the electrode 100f contacts an outer wall 23f of the cathode 22f as shown for the electrical contact. Therefore, the electrode 100f and cathode 22f define adjacent perimeter surfaces that provide both cooling and electrical contact as previously described.

FIG. 17c illustrates an embodiment of a plasma arc torch 10 wherein a third element