Plasma Welding Torch

Abstract

To provide a plasma welding torch with high cooling capacity by expanding a cooling water path without increasing the torch size.SOLUTION: A plasma welding torch 1 for performing plasma welding includes a torch body 20, an electrode 30 provided at the axial center of the torch body 20, a pilot gas path PG provided around the electrode 30, and a cooling water path W2 provided outside the pilot gas path PG, and the cooling water path W2 uses an insulating portion 66 provided as the outer peripheral wall of the pilot gas path PG as the inner peripheral wall of the cooling water path W2, and uses a metal cylindrical portion 69 and / or an insulating cylindrical portion 13 as the outer peripheral wall.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a plasma torch that utilizes the principle of plasma, such as a plasma welding torch, a plasma powder build-up welding torch, and a plasma cutting torch. [Background technology]

[0002] Plasma welding is performed by discharging electricity using an electrode made of a metal such as tungsten as the cathode, and transferring the plasma arc generated during the discharge to the base material through a hole in a water-cooled insert tip. This allows the high-energy-density plasma arc to be transferred to the base material as a highly concentrated high-temperature plasma flow, resulting in effective welding.

[0003] In recent years, there has been a demand for higher current plasma welding due to the diversification of objects to be welded and the improvement of welding efficiency. When plasma welding is performed at a higher current, the amount of heat in the plasma welding torch during welding increases, causing the temperature of the components constituting the torch to rise, which may damage the insert tip in particular. For this reason, it is necessary to increase the flow rate of cooling water supplied for cooling and improve the cooling capacity of the torch. For example, Patent Document 1 discloses a plasma welding torch in which the shape of the opposing surfaces (insertion surface and inserted surface) of the plasma nozzle and the heat dissipation member is made conical to improve the cooling capacity.

[0004] On the other hand, from the viewpoint of welding workability such as handling of the plasma welding torch, it is desirable to reduce the size of the plasma welding torch. For example, Patent Document 2 discloses a technology for reducing the size of the tip of a plasma welding torch. In Patent Document 2, the tip of the plasma welding torch is reduced in size by configuring the shielding gas flow path to be composed of branch paths that are separated in the circumferential direction around the axis of the electrode. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-224830 A [Patent Document 2] JP 2017-124432 A Summary of the Invention [Problem to be solved by the invention]

[0006] A typical plasma welding torch has, for example, from the center radially outward, components such as an electrode (negative potential), a tungsten chuck, a pilot gas path, a metallic tubular portion (same potential as the electrode), an insulating tubular portion, a metallic tubular portion (positive potential), a cooling water path, and a metallic tubular portion (positive potential).In other words, since it is necessary to provide the pilot gas path, the cooling water path, and components that insulate the negative potential from the positive potential within the plasma welding torch, there are design limitations on how small the plasma welding torch can be made.

[0007] For example, the configuration of the plasma welding torch disclosed in the above Patent Document 1 uses a coolant case having a multiple layer structure to form a coolant flow path, and there is a risk that sufficient miniaturization will not be achieved.

[0008] In addition, for example, in the configuration of the plasma welding torch disclosed in the above Patent Document 2, the cooling water flow passage, for example, the axial flow passage, is provided in the torch body and is a flow passage surrounded by a metallic cylindrical member. Therefore, the cross-sectional area of ​​the cooling water flow passage is small, and there is a risk that it cannot sufficiently handle the increase in heat when the plasma welding current is increased. It is possible to expand the cooling water flow passage by thinning the material, but there is a limit to how thin the material can be from the viewpoint of the strength of the parts and the manufacturing costs, and this is not realistic.

[0009] The present invention has been made in consideration of the above circumstances, and aims to provide a plasma welding torch with high cooling capacity by expanding the cooling water path without increasing the torch size. In particular, although the amount of heat increases when a large current is passed through the insert tip and the electrode, the present invention aims to realize high current plasma welding with the existing torch size by expanding the cooling water path and improving the cooling capacity while keeping the torch size the same. [Means for solving the problem]

[0010] In order to achieve the above object, according to the present invention, there is provided a plasma welding torch for performing plasma welding, comprising a torch body, an electrode provided at an axial center portion of the torch body, a pilot gas passage provided around the electrode, and a cooling water passage provided outside the pilot gas passage, wherein the cooling water passage is: In its entire length, A plasma welding torch is provided, characterized in that an insulating portion provided as an outer peripheral wall of the pilot gas path is used as an inner peripheral wall of the cooling water path, and the outer peripheral wall is constructed using a metal tubular portion and an insulating tubular portion.

[0011] The torch body may include a tip base, an insulating spacer, and an electrode base, the metal tubular portion may include the tip base and the electrode base, and the insulating tubular portion may include the insulating spacer.

[0012] The insulating portion may be inserted in communication with a tip base, an insulating spacer, and an electrode base included in the torch body, and the cooling water path may be formed between the insulating portion and the tip base, the insulating spacer, and the electrode base.

[0013] The insulating portion may be inserted in communication with the tip base, insulating spacer, and electrode base included in the torch body, and an insert tip located at the lower end of the torch body, and the cooling water path may be formed between the insulating portion and the tip base, insulating spacer, electrode base, and insert tip.

[0014] The insulating portion may be configured to be removable. Effect of the Invention

[0015] According to the present invention, it is possible to provide a plasma welding torch having high cooling capacity by enlarging the cooling water passage without increasing the torch size. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic explanatory diagram showing an example of the configuration of a small current plasma welding torch. [Diagram 2] FIG. 2 is a schematic explanatory diagram showing an example of the configuration of a cooling water path in a small current plasma welding torch. [Diagram 3] FIG. 1 is a schematic explanatory diagram of a path configuration including a cooling water path in a conventional high current plasma welding torch. [Figure 4] FIG. 1 is a schematic explanatory diagram of a path configuration including a cooling water path in a conventional low-current plasma welding torch. [Diagram 5] 1 is a schematic explanatory diagram of a path configuration including a cooling water path according to an embodiment of the present invention; [Figure 6] FIG. 4 is a schematic explanatory diagram showing an example of the configuration of a high-current plasma welding torch according to another embodiment of the present invention. [Figure 7] FIG. 11 is a schematic explanatory diagram showing an example of the configuration of a cooling water path in a high-current plasma welding torch according to another embodiment of the present invention. [Figure 8] FIG. 1 is a schematic explanatory diagram showing an example of the configuration of a conventional low-current plasma welding torch. [Figure 9] FIG. 1 is a schematic explanatory diagram showing an example of the configuration of a conventional high-current plasma welding torch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and duplicated description will be omitted. In this embodiment, a so-called low-current plasma welding torch will be mainly described as an example. In this specification, the low-current plasma welding torch refers to an indirect water-cooled welding torch in which the cooling water path does not directly contact the insert tip.

[0018] <Plasma welding torch configuration> Fig. 1 is a schematic explanatory diagram showing an example of the configuration of a small-current plasma welding torch 1 according to this embodiment. Also, Fig. 2 is a schematic explanatory diagram showing an example of the configuration of a cooling water path in the small-current plasma welding torch 1. For the purpose of explanation, Figs. 1 and 2 show a schematic cross section of the small-current plasma welding torch 1.

[0019] As shown in Fig. 1, the low current plasma welding torch 1 includes a tip base (positive potential) 10, an insulating spacer 13, and an electrode base (negative potential) 16, and the tip base 10, insulating spacer 13, and electrode base 16 form a torch body 20. As shown in the figure, the tip base 10 and the electrode base 16 are insulated by the insulating spacer 13 above the tip base 10, and the torch body 20 is formed by integrating these by, for example, sealing them in resin. In addition, O-rings (not shown) are used between each member to prevent water leakage and gas leakage. In addition, a torch cap 25 is attached to the upper end of the torch body 20.

[0020] An electrode 30 is disposed at the axial center of the torch body 20 via a chuck member 31. An insulating water passage 32 (corresponding to an insulating part 66 described later) and a centering stone 33 are provided between the electrode 30 and the torch body 20, and the electrode 30 is positioned and fixed at the axial center. The insulating water passage 32 as an insulating part is configured to be removable, and by inserting the insulating water passage 32 from above so as to communicate with the torch body 20 (communicating with the tip base 10, insulating spacer 13, and electrode base 16), a cooling water path W described later is formed between the tip base 10, insulating spacer 13, electrode base 16, and insulating water passage 32. The electrode 30 may be formed of a metal such as tungsten.

[0021] At the lower end of the torch, an insert tip 35 is provided around the electrode 30, and a shield cap 38 is provided around the insert tip 35. At the lower end of the plasma welding torch 1, the lower end (tip) of the insert tip 35 is configured to protrude from an opening in the lower center of the shield cap 38, and a plasma nozzle port 40 is configured in the center as an outlet for the plasma airflow ejected from the lower end of the electrode 30.

[0022] 2, the small current plasma welding torch 1 is equipped with a pilot gas path PG, a cooling water path W, and a shielding gas path SG that are connected to the inside of the torch (see the shaded areas in FIG. 2). The pilot gas path PG is provided around the electrode 30. The cooling water path W is provided outside the pilot gas path PG, and is inserted, for example, into the inside of the torch body 20. The shielding gas path SG is provided further outside the pilot gas path PG and the cooling water path W with respect to the electrode 30. Although not shown here, the cooling water path W may have an inlet and an outlet formed separately around the periphery of the torch body 20.

[0023] The pilot gas path PG ultimately has the role of ejecting pilot gas from the plasma nozzle port 40 at the lower end of the low-current plasma welding torch 1, generating and maintaining a plasma arc, and generating a high-temperature plasma flow to perform welding. In addition, the shielding gas path SG ejects shielding gas from around the insert tip 35, thereby shielding the plasma arc and the base material melted by the plasma arc from the atmosphere.

[0024] The cooling water path W is provided to directly or indirectly cool each of the components constituting the low current plasma welding torch 1, such as the torch body 20, the chuck member 31, the insulating water passage 32, and the insert tip 35. The components to be cooled are optional and vary depending on the torch configuration, but for example, the cooling water path W may be provided to pass through the inside of the tip base 10 so as to directly cool at least a part of the tip base 10. The cooling water path W may also be provided to pass through the inside of the insulating spacer 13 and the electrode base 16 so as to cool at least a part of the insulating spacer 13 and the electrode base 16. During plasma welding, each component of the plasma torch, particularly the electrode 30, the chuck member 31, and the insert tip 35, is subjected to a high heat amount according to the welding current. In order to prevent burnout due to this high temperature, each component is protected by flowing cooling water. However, if the amount of heat generated exceeds the cooling capacity, the parts will burn. For this reason, even with a high current, it is necessary to improve the cooling capacity of the cooling water path W in order to prevent each component from burning.

[0025] On the other hand, there are dimensional constraints on the low-current plasma welding torch 1 based on the shape of the object (workpiece) to be plasma welded with the low-current plasma welding torch 1 and the shape of incidental jigs, etc. Therefore, the present inventors conducted extensive research into the configuration including the peripheral members of the cooling water path W, and devised a new path configuration to expand the cooling water path W without increasing the torch size and improve the cooling capacity.

[0026] Hereinafter, the configuration of the cooling water path W and its peripheral members according to this embodiment will be described with reference to the drawings. In the following description, including in FIG. 1 and FIG. 2, components having the same functional configuration are illustrated with the same reference numerals, and their description may be omitted.

[0027] <Path configuration including conventional cooling water path W1> First, an example of a configuration of a path including a conventional cooling water path W1 will be described. FIG. 3 is a schematic explanatory diagram of a path configuration 50a (50) including a cooling water path W1 in a conventional high-current plasma welding torch. FIG. 9 is a schematic explanatory diagram showing an example of the configuration of a conventional high-current plasma welding torch. Here, the conventional high-current plasma welding torch refers to a direct water-cooled welding torch in which the cooling water path is in direct contact with the insert tip, as shown in FIG. 9. For the purpose of explanation, FIG. 3 shows a conceptual diagram of a path cross section when a part of a conventional high-current plasma welding torch (see the dashed line part in FIG. 9) is enlarged.

[0028] Fig. 4 is a schematic explanatory diagram of a path configuration 50b (50) including a cooling water path W1 in a conventional low-current plasma welding torch. Fig. 8 is a schematic explanatory diagram showing an example of the configuration of a conventional low-current plasma welding torch. Here, the conventional low-current plasma welding torch refers to an indirect water-cooled welding torch in which the cooling water path does not come into contact with the insert tip, as shown in Fig. 8. For the purpose of explanation, Fig. 4 shows a conceptual diagram of a path cross section when a portion of a conventional low-current plasma welding torch (see the dashed line portion in Fig. 8) is enlarged.

[0029] 3, the path configuration 50a is centered around the electrode 30 at the axial center and includes, in order outward, the electrode 30, the chuck member 31, the pilot gas path PG, a metal cylindrical portion 54, an insulating portion 56, a metal cylindrical portion 58, a cooling water path W1, and a metal cylindrical portion 59. Here, the chuck member 31 and the metal cylindrical portion 54 are at the same potential as the electrode 30, and the metal cylindrical portions 58 and 59 are at a positive potential.

[0030] 4, the path configuration 50b is centered around the electrode 30 at the axis and includes, going outward, the electrode 30, the chuck member 31, the pilot gas path PG, an insulating section 56, a metallic cylindrical section 58, a cooling water path W1, and a metallic cylindrical section 59. Here, the chuck member 31 has the same potential as the electrode 30, and the metallic cylindrical sections 58 and 59 have a positive potential.

[0031] 3 and 4, metallic cylindrical portions 58, 59 are provided on both sides to configure the cooling water path W1. Also, an insulating portion 56 made of, for example, ceramic must be provided to electrically insulate members having a negative potential, such as the electrode 30 and the chuck member 31, from members having a positive potential, such as the metallic cylindrical portions 58, 59.

[0032] The inventors focused on the fact that metal cylindrical portions 58, 59 are provided on both sides to form the cooling water path W1, and that the width of the cooling water path W1 relative to the overall diameter of the torch is small because the metal cylindrical portions 58, 59 have a double structure, and devised the following path configuration.

[0033] <Path configuration including the cooling water path W2 according to the embodiment of the present invention> 5 is a schematic explanatory diagram of a path configuration 60 including a cooling water path W2 according to an embodiment of the present invention. For the purpose of explanation, a conceptual diagram of a path cross section is shown in an enlarged view of a portion of the low-current plasma welding torch 1 (see the dashed line portion in FIG. 2).

[0034] 5, the path configuration 60 according to this embodiment is centered on the electrode 30 at the axial center and includes, going outward, the electrode 30, the chuck member 31, the pilot gas path PG, an insulating section 66, a cooling water path W2, and a metal cylindrical section 69. Here, the chuck member 31 has the same potential as the electrode 30, and the metal cylindrical section 69 has a positive potential.

[0035] 5, when configuring the cooling water path W2, one side (inner peripheral wall) is made of an insulating section 66, and the other side (outer peripheral wall) is made of a metal tubular section 69. In the configuration according to the present embodiment, in addition to the metal tubular section 69 including the chip base 10 and the electrode base 16, an insulating tubular section (not shown) including the insulating spacer 13 may be used as the other side (outer peripheral wall).

[0036] In the path configuration 60, the insulating portion 66 serving as the outer peripheral wall of the pilot gas path PG is also used as the inner peripheral wall of the cooling water path W2. This makes it possible to electrically insulate the members having a negative potential, such as the electrode 30 and the chuck member 31, from the members having a positive potential, such as the metallic tubular portion 69, and to increase the flow path width of the cooling water path W.

[0037] In other words, one of the metal cylindrical portions (58, 59) for forming the cooling water path W1 shown in Figures 3 and 4 can be omitted, thereby reducing the number of components. This makes it possible to increase the width of the cooling water path W compared to the previous width (for example, the width of the cooling water path W1) while keeping the torch size (for example, the radial width) of the low-current plasma welding torch 1 unchanged.

[0038] <Action and effect> According to the low-current plasma welding torch 1 having the path configuration 60 including the cooling water path W2 of this embodiment, the cooling water path W2 is configured by forming one side (inner circumference side) as an insulating portion 66 and the other side (outer circumference side) as a metallic cylindrical portion 69 (see FIG. 5). Therefore, the number of components can be reduced compared to the conventional path configuration, and the width of the cooling water path W2 can be increased compared to the conventional width. If the width of the cooling water path W2 is large, the cross-sectional area also increases, making it possible to flow a large amount of cooling water through the cooling water path W2, thereby improving the cooling capacity.

[0039] Also, by designing the torch with a configuration with fewer components such as the cooling water path W2 in a low-current plasma welding torch 1 having the same torch size, it is possible to increase the width of the cooling water path W2 compared to conventional methods without increasing the overall dimensions of the torch, thereby improving the cooling capacity. In other words, by using conventional components and auxiliary jigs that make up the low-current plasma welding torch 1 and improving the cooling capacity, it is possible to pass a large current through the electrode 30 while maintaining the same torch size, and a high current plasma welding is realized.

[0040] For example, by modifying the design of a plasma welding torch that was previously manufactured for small currents (around 15A) and expanding the cooling water path, it is possible to carry approximately twice the current, up to 30A, even for a plasma welding torch of the same size.

[0041] Although the embodiment of the present invention has been described above, the present invention is not limited to such examples. It is clear that a person skilled in the art can come up with various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0042] For example, in the above embodiment, a so-called indirect water-cooled torch in which the cooling water path W does not directly contact the insert tip 35 has been illustrated and described as an example of the configuration of the low-current plasma welding torch 1, but the scope of application of the technology of the present invention is not limited to this. For example, the technology can be similarly applied to a so-called high-current plasma welding torch that is configured so that the cooling water path W is in direct contact with the insert tip and is called a direct water-cooled torch. Below, a case in which the technology of the present invention is applied to a high-current plasma welding torch (direct water-cooled torch) will be described as another embodiment of the present invention.

[0043] <Another embodiment of the present invention> Fig. 6 is a schematic explanatory diagram showing an example of the configuration of a high-current plasma welding torch 100 according to another embodiment of the present invention. Also, Fig. 7 is a schematic explanatory diagram showing an example of the configuration of a cooling water path in the high-current plasma welding torch 100. For the purpose of explanation, Figs. 6 and 7 show a schematic cross section of the high-current plasma welding torch 100.

[0044] As shown in Fig. 6, the high current plasma welding torch 100 includes a tip base (positive potential) 110, an insulating spacer 113, and an electrode base (negative potential) 116, and the tip base 110, the insulating spacer 113, and the electrode base 116 constitute a torch body 120. As shown in the figure, the tip base 110 and the electrode base 116 are insulated by the insulating spacer 113 above the tip base 110, and the torch body 120 is constituted by integrating these by, for example, sealing them in resin. In addition, a configuration is made in which water leakage and gas leakage are prevented between each member by O-rings (not shown). In addition, a torch cap 125 is attached to the upper end of the torch body 120.

[0045] An electrode 130 is disposed at the axial center of the torch body 120 via a chuck member 131. Between the electrode 130 and the torch body 120, a chuck receiver 127, an insulating water passage 132 as an insulating part, and a centering stone 133 are provided, and the electrode 130 is positioned and fixed at the axial center. An insert tip 135 is provided around the electrode 130 at the lower end of the torch. The insulating water passage 132 as an insulating part is configured to be removable, and by inserting the insulating water passage 132 from above so as to communicate with the torch body 120 and the insert tip 135, a cooling water path W is formed between the tip base 110, the insulating spacer 113, the electrode base 116, and the insert tip 135 and the insulating water passage 132. The electrode 130 may be formed of a metal such as tungsten.

[0046] A shield cap 138 is provided around the insert tip 135. At the lower end of the high current plasma welding torch 100, the lower end (tip) of the insert tip 135 is configured to protrude from an opening in the lower center of the shield cap 138, and a plasma nozzle port 140 is configured in the center as an outlet for the plasma airflow ejected from the lower end of the electrode 130.

[0047] 7, the high current plasma welding torch 100 includes a pilot gas path PG, a cooling water path W, and a shielding gas path SG that are connected thereto (see the shaded areas in FIG. 7). The pilot gas path PG is provided around the electrode 130, and pilot gas is supplied from the top of the torch to the periphery of the electrode 130.

[0048] Cooling water path W allows cooling water supplied from the side of the torch body 120 to flow through the inside of the torch body 120 to the inside of the insert tip 135. As shown in the figure, the high current plasma welding torch 100 may be provided with an inlet 150 and an outlet 152 for the cooling water path W. The shielding gas path SG is provided further outside the pilot gas path PG and the cooling water path W with respect to the electrode 130.

[0049] In the high current plasma welding torch 100 according to the present embodiment, the cooling water path W is provided over a wider area. Specifically, a part of the electrode base 116, the entire tip base 110, and a part of the insert tip 135 are configured to be directly cooled by water cooling. By applying the technology of the present invention to the high current plasma welding torch 100 according to the present embodiment, as in the above embodiment, the width of the cooling water path W can be increased compared to the previous width, a large flow rate of cooling water can be flowed, and the cooling capacity can be improved.

[0050] In the high current plasma welding torch 100, the cooling water path W is provided over a wider range, and the cooling capacity is improved significantly when the width of the cooling water path W is increased compared to the previous width. Specifically, by modifying the design of a high current plasma welding torch manufactured for 180A and expanding the cooling water path, it is possible to realize a configuration capable of passing a large current such as 250A. [Industrial Applicability]

[0051] The present invention can be applied to plasma torches that utilize the principles of plasma, such as plasma welding torches, plasma powder build-up welding torches, and plasma cutting torches. [Explanation of symbols]

[0052] 1. Low current plasma welding torch 10…Chip base 13…Insulating spacer 16...Electrode stand 20…Torch body 25…Torch cap 30...electrode 31...Chuck member 32…Insulated waterway 33…Centering Stone 35…Insert chip 38…Shield cap 40…Plasma nozzle port 50 (50a, 50b)... (conventional) route configuration 54...Metal cylindrical section 56…Insulation section 58...Metal tubular section 59...Metal tubular section 60...(Invention) Route Configuration 66…Insulation section 69…Metal tubular section 100...High current plasma welding torch (according to another embodiment) PG: Pilot gas route SG: Shielding gas route W (W1, W2)…Cooling water path

Claims

1. A plasma welding torch for performing plasma welding, The torch includes a torch body, an electrode provided at an axial center of the torch body, a pilot gas passage provided around the electrode, and a cooling water passage provided outside the pilot gas passage, a cooling water passage that uses an insulating portion provided as an outer peripheral wall of the pilot gas passage as an inner peripheral wall of the cooling water passage along its entire length, and that is constructed using a metal tubular portion and an insulating tubular portion as the outer peripheral wall.

2. The torch body includes a tip base, an insulating spacer, and an electrode base, the metal tubular portion includes the chip base and the electrode base, The plasma welding torch according to claim 1 , wherein the insulating cylindrical portion includes the insulating spacer.

3. The insulating portion is inserted into and communicates with a tip base, an insulating spacer, and an electrode base included in the torch body, 3. The plasma welding torch according to claim 1, wherein the cooling water path is formed between the insulating portion and the tip base, the insulating spacer, and the electrode base.

4. The insulating part is inserted in communication with a tip base, an insulating spacer, and an electrode base included in the torch body, and an insert tip located at a lower end of the torch body; 3. The plasma welding torch according to claim 1, wherein the cooling water path is formed between the insulating portion and the tip base, the insulating spacer, the electrode base, and the insert tip.

5. The plasma welding torch according to claim 1 , wherein the insulating portion is configured to be detachable.

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