Welding torch for arc welding or cutting and method of using the same

Abstract

The invention relates to a welding torch for plasma processing. The sealing and electrically conductive connection between the different components (A, B) of the welding torch is achieved by using at least one elastically deformable and electrically conductive sealing member (D).

Description

[0001] The present invention relates to a torch for plasma processing (welding, cutting, spraying, etc.). Since the arc requires electrical energy to be conducted from an energy source toward an electrode located in the center of the torch, different parts of the torch (such as the torch body and the electrode or the torch body and the plasma nozzle) need to be connected to each other in an electrically conductive manner, while other parts need to be electrically isolated from each other in order to prevent short circuits. Usually, the conductive connection is achieved by metal-to-metal contact.

[0002] In such torches, different working fluids are used simultaneously, such as cooling water or air, inert shielding gas and / or reactive shielding gas. Therefore, it is necessary to connect the different parts of the torch in a sealed manner so that the different fluids do not mix or contaminate each other, but remain in their respective channels. Usually, such sealing functions are achieved by using deformable members, such as O-rings or gaskets.

[0003] For maintenance purposes, the welding torch needs to be regularly disassembled and reassembled, which requires the replacement of seals. It is difficult to use typical metal sealing components, such as copper washers or gaskets, because special tools are required to ensure proper sealing function.

[0004] The present invention achieves sealing and conductive connection by using at least one elastically deformable and electrically conductive sealing member. The advantage of doing so is that both functions are provided by the same component, thereby providing greater design freedom and making it possible to minimize the overall size of the welding torch, which is desirable for robotic applications and manual applications (welding, cutting, spraying, etc.). Another advantage is that the tolerances of the accessories can be larger because the conductive connection does not rely on metal-to-metal contact, but is affected by the conductive and elastically deformable sealing member, thereby ensuring conductivity over a wider range of distances. Therefore, electrical contact may also occur on radial surfaces, so that the conductive current does not need to hit the surface, that is, the end surface of the part in the conventional design of the welding torch. This greatly reduces the workload of end machining.

[0005] Suitable materials for the corresponding conductive sealing members are conductive polymers, conductive rubbers or non-conductive elastomers, thermoplastic elastomers, chloroprene rubber, silicone rubber, silicone caulking agents, poly(vinyl chloride) or EPDM, which have conductive fillers and / or coatings, including but not limited to aluminum, silver, copper, nickel or other metal materials or graphite or other carbon-based conductive materials such as carbon black, fullerene or carbon nanotubes. The filler and / or coating materials can be used in the form of particles, fibers or textiles.

[0006] The term "conductive" material in the present application is understood to be a material with a resistivity in the range of 0.002 Ωcm to 20 Ωcm.

[0007] In the present application, the "sealing" function means preventing the fluid from penetrating through the corresponding connection to the extent that the contamination in the target fluid does not exceed 20 ppm (by volume).

[0008] The term "elastically deformable" material in the present application is understood to be a material having a Young's modulus or similar non-linear elastic properties in the range of 0.2 MPa to 2 MPa.

[0009] According to the present invention, the current conducted by at least one conductive and elastically deformable sealing member ranges from 1A to 1500A, more preferably from 1A to 400A, and even more preferably from 1A to 150A, while the sealing of different fluid channels is achieved with a fluid pressure ranging from 0.1MPa to 2MPa, and more preferably from 0.2MPa to 1MPa.

[0010] According to the present invention, an electrically conductive and elastically deformable sealing member may be used on both the anode side and the cathode side of a welding torch.

[0011] In another aspect, the electrically conductive and resiliently deformable sealing member may be part of the main conduction path of the torch, such as in the connection between the torch body and the plasma nozzle, which is particularly preferred since these components often need to be disassembled for maintenance and replacement.

[0012] In another aspect, the electrically conductive and resiliently deformable sealing member may be part of a secondary conductive path, such as a pilot circuit.

[0013] In another aspect, an electrically conductive and resiliently deformable sealing member may be used on consumable parts such as electrodes, particularly flux cored wire feeders.

[0014] Preferably, the at least one electrically conductive and elastically deformable sealing member is in the form of an O-ring. This has the advantage of being simple to assemble and low in production costs.

[0015] In one aspect, a plurality of electrically conductive and elastically deformable sealing members are used. The plurality of electrically conductive and elastically deformable sealing members can be used to connect two components at multiple locations, or to join more than two components into a common conductive path.

[0016] In a particularly preferred embodiment, a plurality of electrically conductive and elastically deformable sealing members in the form of O-rings connect the concentric cylindrical surfaces of the two components in the radial direction. This offers the particular advantage of improving the sealing properties in the axial direction while enhancing the electrical conductivity in the radial direction. Another advantage of such an embodiment is that the possibility of moving the components relative to each other in the axial direction is retained.

[0017] In another advantageous embodiment, the electrically conductive and elastically deformable sealing member connects the two components in the axial direction such that it connects two components having substantially the same transverse dimensions at least in the region where the connection is made.

[0018] Generally speaking, in order to achieve a sealed connection, the size of the sealing member should substantially match the geometry of the components to be connected. This means that when more than two torch components are connected with the electrically conductive and elastically deformable sealing member according to the invention, it is particularly advantageous to use sealing members of different sizes and / or shapes to match the respective geometries of the connected components.

[0019] The welding torch according to the invention is preferably configured for use in welding processes, such as metal inert gas welding, metal active gas welding, tungsten inert gas welding or plasma arc welding, or for use in plasma cutting, marking or spraying processes.

[0020] In a preferred embodiment, in a welding torch according to the invention, the fact that poor conductivity means that the seating of the conductive sealing member is not perfect is used to enhance operational safety. Before starting to use the welding torch in operation, the conductivity between the different welding torch components can be measured and compared with the calibration value. If the difference between the measured value and the calibration value exceeds a set threshold, it is likely that the sealing material has failed or the welding torch has been assembled incorrectly and should not be operated before it is completely modified. Therefore, poor conductivity is an indication that a fluid leak may occur.

[0021] In a similar manner, fluid leakage may also indicate poor electrical contact, and detection of fluid leakage may serve as an indication of improper assembly and / or material failure.

[0022] Hereinafter, the present invention will be described in further detail with reference to a preferred embodiment. Figure 1 Schematically visualized in .

[0023] Figure 1 A schematic cross section of the front part of a welding torch according to an advantageous embodiment of the invention is shown.

[0024] Figure 1 The welding torch shown comprises an electrode E, a plasma nozzle A and a torch body B. The nozzle constricts a plasma F generated from a working gas (active gas or inert gas) by causing an electric current to flow from the electrode E to the nozzle A or a workpiece (not shown). The body B and the nozzle are connected by an electrically conductive and elastically deformable sealing member D in the form of an O-ring. In this case, the O-rings have different diameters but exhibit the same cross-section. These O-rings confine the fluid coolant to the cooling channel C and prevent the fluid coolant from leaking into the flow path of the working gas or plasma F, while ensuring that the potential in the nozzle and the torch body is the same.

Claims

1. A welding torch for plasma processing, the welding torch comprising a welding torch body (B), a nozzle (A) and an electrode (E), wherein at least two of the welding torch body (B), the nozzle (A) and the electrode (E) are connected to each other in an electrically conductive manner, characterized in that: The at least two components are connected to each other via at least one electrically conductive and elastically deformable sealing member (D).

2. The welding torch according to claim 1, characterized in that The at least two components are part of a main conductive path of the welding torch.

3. The welding torch according to claim 1 or 2, characterized in that: The sealing member (D) is a conductive O-ring.

4. The welding torch according to claim 1 or 2, characterized in that: The welding torch comprises a plurality of electrically conductive and elastically deformable sealing members (D), wherein at least two of the electrically conductive and elastically deformable sealing members are geometrically different from each other.

5. The welding torch according to claim 1 or 2, characterized in that: Two of the at least two components are the torch body (B) and the nozzle (A).

6. The welding torch according to claim 1 or 2, characterized in that: The torch is configured to be usable for a process selected from the group consisting of: plasma arc welding and plasma cutting, marking and spraying.

7. The welding torch according to claim 1 or 2, characterized in that: The at least one electrically conductive and elastically deformable sealing member (D) comprises at least one material selected from the group consisting of: a conductive polymer, a conductive rubber or a non-conductive elastomer, a thermoplastic elastomer, and optionally coated with a layer containing aluminum, conductive fabric, silver, nickel or graphite or dispersed with conductive particles of aluminum, silver, copper, nickel, graphite or carbon.

8. The welding torch according to claim 1 or 2, characterized in that: The at least one electrically conductive and elastically deformable sealing member (D) comprises at least one material selected from the group consisting of: neoprene, silicone rubber, silicone caulk, polyvinyl chloride and EPDM, and is optionally coated with a layer containing aluminum, conductive fabric, silver, nickel or graphite or dispersed with conductive particles of aluminum, silver, copper, nickel, graphite or carbon.

9. A plasma treatment method, comprising arc welding and / or cutting and / or spraying, characterized in that: A welding torch according to any one of claims 1 to 8 is used.

10. The method according to claim 9, characterized in that The method comprises the step of verifying the leaktight connection of the at least two connected components by measuring the electrical conductivity between the at least two components.

11. The method according to claim 9, characterized in that The method comprises the step of verifying the electrically conductive connection of the at least two components by detecting fluid leakage.

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