Welding torch, arc welding apparatus, and arc welding method

Abstract

To provide a welding torch which enables improvement of a work environment and welding workability, and to provide an arc welding device and an arc welding method.SOLUTION: A welding torch 10 has: a welding torch body which supplies a welding wire 12 to a base material; a contact tip 13 which guides the welding tire 12; a nozzle 15 which surrounds the contact tip 13 and forms a shield gas supply passage 14 between at least the contact tip 13 and itself; and a first cylindrical member 16 which surrounds the nozzle 15. The first cylindrical member 16 has: a contact part 17 which is placed in contact with a base material and located in a base material side tip; and a first gas discharge port 18 which is spaced apart from the contact part 17 and formed at a position facing an outer peripheral surface of the nozzle 15. Further, a first discharge passage 19 communicating with the first gas discharge port 18 is formed between the nozzle 15 and the first cylindrical member 16.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a welding torch, an arc welding apparatus having the welding torch, and an arc welding method.

Background Art

[0002] Conventionally, gas shielded arc welding has been carried out in a wide range of fields, and various studies have been conducted on the weldability during welding. For example, Patent Document 1 proposes an apparatus for performing a welding operation so that substances inconvenient for a welder are removed. The apparatus described in Patent Document 1 is an apparatus for performing a welding operation, and includes a central member capable of guiding a welding wire therein, a removal member disposed outside the central member for removing substances inconvenient for a welder, and a gas supply member disposed outside the removal member for supplying gas. According to the configuration of the above apparatus, since the fumes generated during welding are exhausted through the fume gas outlet passage and the exhaust duct, it is possible to suppress the scattering of the fumes to the surroundings.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the apparatus described in Patent Document 1 is used, depending on the structure of the removal member and the suction conditions, the flow state of the shielding gas may be deteriorated, resulting in deteriorated shielding performance and leading to the occurrence of porosity defects by entraining the atmosphere. In addition, factors that deteriorate the environment of the welder and the weldability include not only fumes but also spatter and arc light. However, even when the conventional welding apparatus is used, it is impossible to completely prevent spatter and arc light.

[0005] Furthermore, when welding an aluminum or aluminum alloy material by MIG (Metal Inert Gas) arc welding, in addition to the specific strong light, soot composed of Mg oxide etc. called "smut" adheres to the surface. Therefore, there arises a problem that the working environment and the appearance after construction deteriorate. Therefore, generally, as necessary, a process for scraping smut, a pickling process, etc. are required to remove the smut.

[0006] Also, when forming a rivet-shaped weld metal by MIG arc spot welding (ASW: Arc Spot Welding) at the position where a hole is formed, with an aluminum alloy plate as the lower plate and a steel plate having a hole as the upper plate, if electrodeposition coating is applied to the surface of the steel plate, since the electrodeposition coating film has poor wettability with the metal, the weld metal is difficult to spread. As a result, the head of the rivet-shaped weld metal may easily come out of the hole, and the joining strength may decrease.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a welding torch capable of improving the working environment and welding workability, preferably capable of preventing a decrease in joining strength, an arc welding apparatus having the welding torch, and an arc welding method.

Means for Solving the Problems

[0008] The above object of the present invention is achieved by the following configuration (1) related to the welding torch.

[0009] (1) A welding torch main body part for supplying a welding wire to a base material, A contact tip for guiding the welding wire, A nozzle surrounding the periphery of the contact tip and forming a supply path for shielding gas at least between the nozzle and the contact tip, A first cylindrical member surrounding the periphery of the nozzle, and having The first cylindrical member has a contact portion that contacts the base material at the tip on the base material side, and a first gas discharge port that is separated from the contact portion and is formed at a position facing the outer peripheral surface of the nozzle. A first discharge path that communicates with the first gas discharge port is configured between the nozzle and the first cylindrical member. A welding torch, characterized in that.

[0010] Further, a preferred embodiment of the present invention relating to a welding torch relates to the following (2) to (5).

[0011] (2) The welding torch according to (1), characterized in that the contact portion has an elastic sealing member at a position where it contacts the base material.

[0012] (3) The nozzle has an extension portion whose tip on the base material side extends to a position substantially on the same plane as the contact portion. The extension portion has a nozzle-side gas discharge port that communicates with the first discharge path. The tip surface of the extension portion has a nozzle tip hole through which the shielding gas and the welding wire pass, and a concave portion centered on the nozzle tip hole. The welding torch according to (1) or (2), characterized in that.

[0013] (4) Further, it has a second cylindrical member that surrounds the periphery of the first cylindrical member. The second cylindrical member has a second gas discharge port, and a second discharge path that communicates with the first discharge path is configured between the first gas discharge port and the second gas discharge port. The welding torch according to any one of (1) to (3), characterized in that.

[0014] (5) The second gas discharge port is configured between the first cylindrical member and the second cylindrical member at a position closer to the base material side than the first gas discharge port. The first cylindrical member has a flange portion that extends outward in the circumferential direction of the first cylindrical member on the base material side of the second gas discharge port. The welding torch according to (4), characterized in that.

[0015] Further, the above object of the present invention is achieved by the following configuration (6) related to an arc welding apparatus.

[0016] (6) A welding torch according to any one of (1) to (5), and a dust collecting device that collects the gas flowing through the first discharge path, characterized by an arc welding apparatus.

[0017] Further, the above object of the present invention is achieved by the following configurations (7) to (10) related to an arc welding method.

[0018] (7) An arc welding method in which an arc is generated between a welding wire and a base material while supplying a shielding gas to the tip of the welding wire to weld the base material, characterized in that a shielding space for shielding the shielding gas is formed in a region from the surface of the base material to a position spaced apart from the surface of the base material in a perpendicular direction by a predetermined interval.

[0019] (8) An arc welding method having a step of generating an arc between the welding wire and the base material using the welding torch according to any one of (1) to (5) to weld the base material, characterized in that, in the step of welding the base material, with the contact portion of the first cylindrical member in contact with the base material, the shielding gas supplied from the tip of the nozzle to the tip of the welding wire is discharged through the first discharge path.

[0020] (9) An arc welding method having a step of generating an arc between the welding wire and the base material using the welding torch according to (3) to weld the base material, wherein the step of welding the base material includes a step of discharging the shielding gas supplied from the tip of the nozzle to the tip of the welding wire through the first discharge path with the contact portion of the first cylindrical member in contact with the base material, and a step of controlling the shape of the weld metal at the tip surface of the extending portion.

[0021] An arc welding method having a step of generating an arc between the welding wire and the base material using the welding torch according to (10), (4), or (5) to weld the base material, In the step of welding the base material, with the contact portion of the first cylindrical member in contact with the base material, the shielding gas supplied from the tip of the nozzle to the tip of the welding wire is discharged from the second gas discharge port through the first discharge path and the second discharge path. An arc welding method characterized by that.

Effect of the Invention

[0022] According to the present invention, it is possible to prevent fumes, spatter, and spatters from scattering around, and to prevent the arc light from adversely affecting the welding operator. Thus, it is possible to provide a welding torch, an arc welding apparatus, and an arc welding method that can improve the working environment and welding workability.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Figure 10

BEST MODE FOR CARRYING OUT THE INVENTION

[0024] Hereinafter, embodiments of the welding torch, arc welding apparatus, and arc welding method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below, and can be arbitrarily modified and implemented without departing from the gist of the present invention. Also, the present invention includes those in which the configurations of the first to third embodiments described below are appropriately combined.

[0025] [First Embodiment] [Welding Torch] FIG. 1 is a schematic diagram showing a welding torch according to the first embodiment of the present invention. Further, FIG. 2 is a cross-sectional view showing an enlarged part of FIG. 1. The welding torch according to the first embodiment will be described with reference to FIGS. 1 and 2.

[0026] The welding torch 10 has a welding torch main body 11, a contact tip 13, a nozzle 15, a first cylindrical member 16, and a second cylindrical member 21. The welding torch main body 11 supplies the welding wire 12 and the shielding gas 35 toward the base materials (steel plate 1 and aluminum alloy plate 2). The contact tip 13 is supported by the welding torch main body 11 and guides the welding wire 12 supplied from the welding torch main body 11 to a predetermined position on the base material. The cylindrical nozzle 15 is supported by the welding torch main body 11 in the same manner as the contact tip 13, and is disposed around the contact tip 13 so as to surround the contact tip 13. And a shielding gas supply passage 14 is formed between the nozzle 15 and the contact tip 13.

[0027] The cylindrical first cylindrical member 16 is attached to the nozzle 15 and is arranged so as to surround the periphery of the nozzle 15. Further, the first cylindrical member 16 has an elastic seal member 20 made of heat-resistant rubber in the entire circumferential direction at the tip on the base material side, and the elastic seal member 20 has a contact portion 17 that contacts the base material. Therefore, when the contact portion 17 is brought into contact with the base material, a shielding space S1 is formed inside the first cylindrical member 16, in which one end face of the first cylindrical member 16, that is, the surface on which the contact portion 17 is formed, is blocked by the base material.

[0028] Furthermore, the first cylindrical member 16 is formed with first gas discharge ports 18 that penetrate in the thickness direction of the first cylindrical member 16 at a plurality of positions that are separated from the contact portion 17 and face the outer peripheral surface of the nozzle 15. And a first discharge path 19 is configured between the shielding space S1 and the first gas discharge ports 18.

[0029] A cylindrical second cylindrical member 21 having a larger diameter than the first cylindrical member 16 is attached to the first cylindrical member 16 on the side of the welding torch main body portion 11 in the first cylindrical member 16. The second cylindrical member 21 surrounds the first cylindrical member 16 and is arranged so that at least the first gas discharge ports 18 are hidden. Therefore, the end portion on the base material side of the second cylindrical member 21 is located on the base material side of the first gas discharge ports 18 and is open, and a second gas discharge port 22 is configured between this end portion and the outer peripheral surface of the first cylindrical member 16. On the other hand, the end portion of the second cylindrical member on the side opposite to the base material is attached to the first cylindrical member and is blocked. And a second discharge path 23 communicating with the first discharge path 19 is configured between the first gas discharge ports 18 and the second gas discharge ports 22.

[0030] Note that a male screw portion 15a is formed at a predetermined position on the outer peripheral surface of the nozzle 15, and a female screw portion 16b is formed at a predetermined position on the inner peripheral surface of the first cylindrical member 16. By screwing these together, the first cylindrical member 16 is attached to the nozzle 15. Further, a male screw portion 16a is formed on the outer peripheral surface facing the position where the female screw portion 16b of the first cylindrical member 16 is formed, and a female screw portion 21b is formed at a predetermined position on the inner peripheral surface of the second cylindrical member 21. By screwing these together, the second cylindrical member 21 is attached to the nozzle 15 via the first cylindrical member 16. Therefore, the first cylindrical member 16 and the second cylindrical member 21 are each configured to be removable from the nozzle 15.

[0031] Further, in the present embodiment, when the height of the second cylindrical member 21 is changed by the degree of screwing between the second cylindrical member 21 and the first cylindrical member 16, the width of the second gas discharge port 22 is configured to change, and the degree of gas discharge from the second gas discharge port 22 can be controlled.

[0032] <Arc Welding Method> Next, an arc welding method using the welding torch according to the first embodiment will be described with reference to FIG. 2.

[0033] (Step of preparing the base material) First, a steel plate 1 is superposed on an aluminum alloy plate 2 as a base material. A hole 1a is provided in advance at the planned joining position of the steel plate 1 with the aluminum alloy plate 2.

[0034] (Step of welding the base material) Next, the welding torch 10 is arranged above the base materials (steel plate 1 and aluminum alloy plate 2) so that the welding wire 12 is positioned at the center of the hole 1a in the steel plate 1. Then, with the contact portion 17 in the elastic seal member 20 of the first cylindrical member 16 in contact with the upper surface of the steel plate 1, as indicated by the arrow in FIG. 2, shielding gas 35 is supplied toward the tip of the welding wire 12 through the shielding gas supply passage 14 between the contact tip 13 and the nozzle 15. Thereby, the shielding space S1 surrounded by the first cylindrical member 16 is filled with the shielding gas 35. By continuously supplying the shielding gas 35, the shielding gas 35 in the shielding space S1 is discharged to the outside from the second gas discharge port 22 through the first discharge passage 19 between the nozzle 15 and the first cylindrical member 16, the first gas discharge port 18 provided in the first cylindrical member 16, and the second discharge passage 23 between the first cylindrical member 16 and the second cylindrical member 21.

[0035] Then, while flowing the shielding gas 35 toward the shielding space S1, a voltage is applied to the welding wire 12 and the aluminum alloy plate 2 to generate an arc between them. Thereby, the welding wire 12 made of aluminum or an aluminum alloy and the aluminum alloy plate 2 are melted, the hole 1a is filled with a welding metal (not shown), a welding metal having a diameter larger than that of the hole 1a is formed above the hole 1a and on the upper surface of the steel plate 1, and the aluminum alloy plate 2 and the steel plate 1 are joined by the welding metal.

[0036] In the welding torch and arc welding method according to the first embodiment, the contact portion 17 of the first cylindrical member 16 is in contact with the base material. For this reason, in a region from the surface of the base material to a position separated from the surface of the base material at a predetermined interval in the perpendicular direction to the surface of the base material, specifically, in a region from the surface of the base material to the first gas discharge port 18 of the first cylindrical member 16, a shielding space S1 for shielding the shielding gas 35 is formed. And since welding is performed within this shielding space S1, it is possible to suppress the fumes, spatter, and spatters generated during welding from scattering outward from the first cylindrical member 16. Further, since the second cylindrical member 21 is arranged so as to hide the first gas discharge port 18 formed in the first cylindrical member 16, it is possible to prevent the deterioration of the working environment due to the generation of arc light within the visual field range of the welding operator.

[0037] Further, in the present embodiment, since the first cylindrical member 16 and the second cylindrical member 21 are configured to be detachable from the nozzle 15, even if fumes, spatter, spatters, etc. adhere to the inner surface of the first cylindrical member 16, they can be easily removed and cleaned or replaced. Therefore, the welding workability can be improved.

[0038] Furthermore, in the present embodiment, by changing the screwing strength between the second cylindrical member 21 and the first cylindrical member 16, the gas discharge amount from the second gas discharge port 22 can be controlled. Therefore, the gas discharge amount can be increased or decreased as needed, and the filling amount of the shielding gas 35 into the shielding space S1 can be adjusted.

[0039] In the first embodiment described above, the elastic seal member 20 is attached to the tip of the first cylindrical member 16 on the base material side. As a result, the contact portion 17 of the first cylindrical member 16 and the steel plate 1 can be brought into close contact without a gap. As a result, an excellent effect of preventing the scattering of fumes, spatter, and smut can be obtained. However, in the present invention, the elastic seal member 20 may not be attached, and the tip surface of the first cylindrical member 16 on the base material side may be used as the contact portion 17. Even with such a configuration, depending on the surface shape of the steel plate 1, the welding posture, etc., the scattering of fumes, spatter, and smut can be sufficiently prevented.

[0040] Further, the welding torch 10 according to the first embodiment has the second cylindrical member 21 surrounding the first cylindrical member 16, but the second cylindrical member 21 is not necessarily required. Specifically, the shielding gas 35 in the shielding space S1 may be discharged to the outside from the first gas discharge port 18 provided in the first cylindrical member 16 through the first discharge path 19 between the nozzle 15 and the first cylindrical member 16. Even with such a configuration, compared with a conventional welding torch to which the first cylindrical member 16 is not attached, it is possible to prevent the scattering of fumes, spatter, and smut and to prevent the deterioration of the working environment due to arc light.

[0041] [Second Embodiment] <Welding Torch> FIG. 3 is a cross-sectional view showing a part of the welding torch according to the second embodiment of the present invention in an enlarged manner. In the second embodiment shown in FIG. 3, the same components as those in the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed descriptions of the welding torch and the arc welding method are omitted or simplified. Further, since the overall view of the welding torch 40 according to the second embodiment shown in FIG. 3 is the same as that in FIG. 1, the illustration thereof is omitted.

[0042] In the second embodiment, the nozzle 15 has an extension portion 25 whose tip on the base material side extends to a position substantially flush with the contact portion 17 of the first cylindrical member 16. The extension portion 25 is made of the same copper as the nozzle 15, and a nozzle-side gas discharge port 24 is formed near the tip. The nozzle-side gas discharge port 24 communicates with a first discharge passage 19 formed between the nozzle 15 and the first cylindrical member 16. Further, the tip surface 25a of the extension portion 25 has a nozzle tip hole 26 through which the shielding gas 35 and the welding wire 12 pass, and a concave portion 27 centered on the nozzle tip hole 26.

[0043] In the second embodiment, the first cylindrical member 16 is formed with a flange portion 28 that extends outward in the circumferential direction of the first cylindrical member 16 on the base material side with respect to the second gas discharge port 22.

[0044] <Arc welding method> The arc welding method using the welding torch 40 according to the second embodiment will be described with reference to FIG. 3. Since the process of preparing the base material is the same as that of the first embodiment, the description thereof is omitted.

[0045] (Step of welding the base material) Similar to the arc welding method according to the first embodiment, welding is performed while filling the shielding space S1 with the shielding gas 35 in a state where the contact portion 17 of the elastic seal member 20 of the first cylindrical member 16 is in contact with the upper surface of the steel plate 1. In this embodiment, the shielding gas 35 that has passed through the shielding gas supply passage 14 is filled into the shielding space S1 through the nozzle-side gas discharge port 24. Further, since the shielding space S1 is shielded by the first cylindrical member 16, the shielding gas 35 is also supplied to the small space S2 between the concave portion 27, the steel plate 1, and the aluminum alloy plate 2 through the nozzle tip hole 26. Thereafter, the shielding gas 35 in the small space S2 moves to the shielding space S1 through the nozzle tip hole 26 and the nozzle-side gas discharge port 24. The passage of the shielding gas 35 after the shielding space S1 is the same as that of the first embodiment.

[0046] Thereafter, an arc is generated between the welding wire 12 and the aluminum alloy plate 2 to form welding metal inside the hole 1a of the steel plate 1 and on the upper surface of the steel plate 1. At this time, the shape of the welding metal is controlled by the tip surface 25a of the extending portion 25.

[0047] Also in the welding torch 40 and the arc welding method according to the second embodiment, since the shielding space S1 is formed by the first cylindrical member 16, it is possible to suppress fumes, spatter, and spatters generated during welding from scattering outward from the first cylindrical member 16, and the working environment of the welder can be kept good. Further, when electrodeposition coating is applied to the upper surface of the steel plate 1, the electrodeposition coating film has poor wettability with the metal, so the welding metal is less likely to spread. On the other hand, according to the present embodiment, the tip surface 25a of the extending portion 25 has the concave portion 27, and the head of the molten metal can be expanded in a direction parallel to the upper surface of the steel plate 1 by the concave portion 27 and the shape can be adjusted, so that excellent joint strength can be obtained. In the present embodiment, since the extending portion 25 is made of copper, the molten metal and the tip surface 25a of the extending portion 25 are not joined, and a welding metal having an excellent shape along the shape of the concave portion 27 can be obtained.

[0048] Here, for example, when welding is performed using the welding torch 10 according to the first embodiment, if Mg or the like in the welding wire 12 is mixed as an oxide in the shielding gas 35 discharged from the second gas discharge port 22 through the second discharge path 23, this oxide may be discharged together with the shielding gas 35 and spatters may occur. In the present embodiment, since the first cylindrical member 16 is formed with the flange portion 28 extending outward in the circumferential direction thereof, Mg oxide or the like discharged from the second gas discharge port 22 toward the base material side can be received on the upper surface of the flange portion 28. Therefore, according to the present embodiment, it is possible to completely prevent even a small amount of spatters that may diffuse outside the first cylindrical member 16.

[0049] When the extending portion 25 of the nozzle 15 extends to a position on the same plane as the contact portion 17 of the first cylindrical member 16, the tip of the extending portion 25 contacts the upper surface of the steel plate 1, similar to the first cylindrical member 16. Therefore, a welded metal with an excellent shape can be obtained. However, the extending portion 25 of the nozzle 15 does not necessarily need to be exactly on the same plane as the contact portion 17 of the first cylindrical member 16. For example, even when the tip of the extending portion 25 is slightly separated from the upper surface of the steel plate 1 with the contact portion 17 of the first cylindrical member 16 in contact with the upper surface of the steel plate 1, the effect of controlling the shape of the welded metal can be sufficiently obtained.

[0050] [Third Embodiment] <Arc Welding Device> FIG. 4 is a schematic diagram showing an arc welding device according to the third embodiment of the present invention. In the third embodiment shown in FIG. 4, the same components as those in the first embodiment shown in FIG. 2 are denoted by the same reference numerals, and detailed descriptions of the welding torch and the arc welding method are omitted or simplified. Also, since the overall view of the welding torch 50 in the third embodiment shown in FIG. 4 is the same as that in FIG. 1, the illustration thereof is omitted.

[0051] In the third embodiment, the arc welding device 51 includes a welding torch 50 and a dust collecting device 34 connected to the welding torch 50. In the welding torch 50, the second cylindrical member 21 surrounding the first cylindrical member 16 is composed of a lower member 29 and an upper member 30. The lower member 29 is fixed to the first cylindrical member 16 at an end on the base material side rather than the first gas discharge port 18 of the first cylindrical member 16 and is closed, and the end on the side opposite to the base material rather than the first gas discharge port 18 is open. The upper member 30 is attached to the lower member at the end on the base material side and is attached to the nozzle 15 at the other end and is closed. Further, a through hole serving as the second gas discharge port 31 is provided on the side surface of the upper member 30, and a hose connection portion 32 protruding outward is provided at a position where this through hole is formed. Furthermore, the hose connection portion 32 is connected to the dust collecting device 34 by a hose 33.

[0052] <Arc Welding Method> The arc welding method using the arc welding apparatus 51 according to the third embodiment is different from the arc welding method described in the first embodiment only in the flow path of the shielding gas 35, and the other steps are almost the same as those in the first embodiment. Therefore, regarding the parts different from the first embodiment, the arc welding method according to the third embodiment will be described below.

[0053] (Step of welding the base material) Before generating an arc between the welding wire 12 and the aluminum alloy plate 2, the shielding gas 35 is supplied toward the tip of the welding wire 12 through the shielding gas supply path 14, and the shielding space S1 surrounded by the first cylindrical member 16 is filled with the shielding gas 35. Then, the shielding gas 35 in the shielding space S1 is discharged from the first discharge path 19 between the nozzle 15 and the first cylindrical member 16, the first gas discharge port 18 provided in the first cylindrical member 16, the second discharge path 23 between the first cylindrical member 16 and the second cylindrical member 21, and the second gas discharge port 31, and is collected by the dust collector 34 via the hose 33.

[0054] In the welding method using the arc welding apparatus 51 according to the third embodiment as well, the same effects as those in the first embodiment can be obtained. Further, according to the present embodiment, the shielding gas 35 flowing through the first discharge path is discharged from the second gas discharge port 31 through the first gas discharge port 18 and the second discharge path 23 together with oxides such as Mg generated by welding, and can be completely recovered by the dust collector 34. Therefore, it is possible to completely prevent the spatter from spreading outside the first cylindrical member 16.

[0055] Note that the nozzle 15 in the arc welding apparatus 51 according to the third embodiment may have an extension portion 25 as shown in the second embodiment. Thereby, even when the steel plate 1 having an electrodeposition coating film formed on the upper surface is used, a weld metal with an excellent shape can be obtained, and a high bonding strength can be obtained.

[0056] Next, the welding method, base material, and welding wire that are preferably used in the present embodiment will be described below.

[0057] <Welding method> The welding torch and arc welding apparatus according to the present invention are applicable to a gas shielded arc welding method in which an arc is generated between a welding wire and a base material for welding, and other welding conditions and the like are not particularly limited. For example, it can be particularly preferably used for welding methods in which a specific strong arc light and spatters are generated, such as MIG arc welding. Further, the welding torch according to the second embodiment is particularly suitable when electrodeposition coating is applied to the surface of the steel plate to be the upper plate in MIG arc spot welding in which the upper plate and the lower plate are joined by forming a rivet-shaped welding metal in the hole of the upper plate.

[0058] <Base material> In the arc welding method according to the present invention, the type of the base material is not particularly limited, but a steel plate, aluminum, or an aluminum alloy plate can be used.

[0059] <Welding wire> In the arc welding method according to the present invention, the type of the welding wire is not particularly limited, and it can be appropriately selected according to the base material and the performance of the required welding metal. It is known that spatters are generated when an Al-Mg based welding wire is used. Therefore, the present invention that can suppress the generation of spatters over a wide range is particularly suitable when an Al-Mg based welding wire is used.

Example

[0060] [First embodiment] <Spot welding> As an example of the invention, spot welding was performed using the welding torch 10 shown in FIG. 2, and the adhesion of spatter around the welded metal was evaluated. FIG. 5 is a perspective view showing the spot welding method for evaluating the invention example in the first embodiment, FIG. 6 is a side view thereof, and FIG. 7 is a top view thereof. As shown in FIGS. 5 to 7, a steel plate 1 provided with a plurality of holes 1a was overlapped and arranged on an aluminum alloy plate 2, and a back plate (not shown) was arranged under the aluminum alloy plate 2, and spot welding was performed on each hole 1a. The types of the steel plate 1 and the aluminum alloy plate 2, and the welding conditions are shown below.

[0061] Steel plate 1: GA980MPa grade steel sheet, thickness 1.4 mm Aluminum alloy plate: 6000 series aluminum alloy plate, thickness 2.0 mm Welding machine power source: Pulse MAG / MIG welding power source Welbee Inverter P500L, manufactured by Daihen Corporation Current-voltage (command value): 150 A - 25 V Current-voltage (measured value): 153 A - 25 V Arc time: 2.0 seconds Shielding gas: 100% Ar Welding wire: A-5356WY, wire diameter 1.2 mm Others: With wire supply control (synchronization feed mode)

[0062] Note that the steel plate 1 and the aluminum alloy plate 2 are rectangular in top view. The steel plate 1 has a width of 150 mm and a longitudinal length of 500 mm, and a total of 60 holes 1a with a diameter of 9 mm are formed at intervals of 30 mm in the width direction and 15 rows at intervals of 30 mm in the longitudinal direction. Then, welding metal was formed in order on the 4 holes 1a closest to the longitudinal end face of the steel plate 1, and then welding metal was formed on the 4 holes 1a in the adjacent row, and this was repeated until the 8th row, and welding was performed on a total of 32 holes 1a.

[0063] As a comparative example, a steel plate having one hole was placed on an aluminum alloy plate, and spot welding was performed using a conventional welding torch to which the first cylindrical member 16, the second cylindrical member 21, etc. were not attached.

[0064] <Evaluation of Smartness and Working Environment> FIG. 8 is a photographic substitute for a drawing showing the welded metal and its surroundings in the inventive example. The arrows in FIG. 8 indicate the order of welding from the start of welding to the eighth hole, and welding is thereafter carried out in the same order. Further, FIG. 9 is a photographic substitute for a drawing showing the welded metal and its surroundings in the comparative example. As shown in FIG. 8, when welding was carried out using the welding torch according to the present invention, on the inner side of the first cylindrical member 16, a smart 61 adhered around the welded metal 60, but almost no smart adhered to the outside of the first cylindrical member 16. Also, during welding, no arc light was visible to the welder, and welding could be carried out in an excellent working environment. Note that since the same excellent results were obtained for all 32 welds, the welding was completed at 32 locations.

[0065] On the other hand, as shown in FIG. 9, for the comparative example in which welding was carried out using a conventional welding torch, a smart 71 diffused and adhered over a wide area around the welded metal 70. Also, a strong arc light was generated during welding, resulting in a poor working environment.

[0066] [Second Embodiment] <Spot Welding> Two sets of base materials were prepared by stacking and arranging a steel plate 1 having a hole 1a and having an electrodeposition coating film 1b formed on its surface on an aluminum alloy plate 2, and spot welding was carried out using different welding torches to evaluate the shape of the welded metal. Specifically, for test material No. 1, the welding torch 10 shown in FIG. 2 was used, and for test material No. 2, the welding torch 40 shown in FIG. 3 was used. The welding conditions and the like were the same as those in the first embodiment described above.

[0067] <Evaluation of Shape of Welded Metal> Figure 10 is a drawing substitute photograph showing the appearance and cross-section of the weld metal of each test piece. As shown in Figure 10, for test piece No. 1, the spread of the head of the weld metal 62 became smaller compared to the weld metal 60 of the first embodiment where the electrodeposition coating film 1b was not formed. On the other hand, for test piece No. 2 using the welding torch 40 shown in Figure 3, compared to test piece No. 1, the head of the weld metal 63 spread, and a joint portion having excellent strength was formed.

Explanation of Signs

[0068] 1 Steel plate 2 Aluminum alloy plate 1a Hole 10, 40, 50 Welding torch 13 Contact tip 14 Shield gas supply path 15 Nozzle 16 First cylindrical member 17 Contact portion 18 First gas discharge port 19 First discharge path 20 Elastic seal member 21 Second cylindrical member 22, 31 Second gas discharge port 23 Second discharge path 24 Nozzle side gas discharge port 25 Extension portion 28 Flange portion 34 Dust collector 35 Shield gas 60, 62, 63, 70 Weld metal 61, 71 Smart

Claims

1. A welding torch body for supplying a welding wire to a base material, a contact tip for guiding the welding wire, a nozzle surrounding the periphery of the contact tip and forming a supply path for shielding gas at least between the contact tip and the nozzle, and a first cylindrical member surrounding the periphery of the nozzle, wherein the first cylindrical member has a contact portion that contacts the base material at the tip on the base material side, and a first gas discharge port formed at a position spaced apart from the contact portion and facing the outer peripheral surface of the nozzle, and a first discharge path communicating with the first gas discharge port is formed between the nozzle and the first cylindrical member. The welding torch is characterized by this.

2. The welding torch according to claim 1, wherein the contact portion has an elastic sealing member at the position where it contacts the base material.

3. The nozzle has an extension portion whose tip on the base material side extends to a position where it is substantially on the same plane as the contact portion, the extension portion has a nozzle-side gas discharge port communicating with the first discharge path, and the tip surface of the extension portion has a nozzle tip hole for passing the shielding gas and the welding wire, and a concave surface portion centered on the nozzle tip hole. The welding torch according to claim 1 is characterized by this.

4. Furthermore, it has a second cylindrical member surrounding the periphery of the first cylindrical member, the second cylindrical member has a second gas discharge port, and a second discharge path communicating with the first discharge path is formed between the first gas discharge port and the second gas discharge port. The welding torch according to claim 1 is characterized by this.

5. The second gas discharge port is formed between the first cylindrical member and the second cylindrical member at a position closer to the base material side than the first gas discharge port, and the first cylindrical member has a flange portion extending outward in the circumferential direction of the first cylindrical member on the base material side of the second gas discharge port. The welding torch according to claim 4 is characterized by this.

6. A welding torch according to any one of claims 1 to 5, and a dust collecting device for collecting the gas flowing through the first discharge path. The arc welding device is characterized by this.

7. An arc welding method for welding a base material by generating an arc between a welding wire and a base material while supplying shielding gas to the tip of the welding wire. An arc welding method, characterized in that a shielding space for shielding the shielding gas is formed in a region from the surface of the base material to a position spaced apart from the surface of the base material at a predetermined interval in a direction perpendicular to the surface of the base material.

8. An arc welding method having a step of generating an arc between the welding wire and the base material and welding the base material by using the welding torch according to any one of claims 1 to 5, In the step of welding the base material, with the contact portion of the first cylindrical member in contact with the base material, the shielding gas supplied from the tip of the nozzle to the tip of the welding wire is discharged through the first discharge passage. An arc welding method characterized by this.

9. An arc welding method having a step of generating an arc between the welding wire and the base material and welding the base material by using the welding torch according to claim 3, The step of welding the base material includes a step of discharging the shielding gas supplied from the tip of the nozzle to the tip of the welding wire through the first discharge passage with the contact portion of the first cylindrical member in contact with the base material, And a step of controlling the shape of the weld metal at the tip surface of the extending portion. An arc welding method characterized by this.

10. An arc welding method having a step of generating an arc between the welding wire and the base material and welding the base material by using the welding torch according to claim 4 or 5, In the step of welding the base material, with the contact portion of the first cylindrical member in contact with the base material, the shielding gas supplied from the tip of the nozzle to the tip of the welding wire is discharged from the second gas discharge port through the first discharge passage and the second discharge passage. An arc welding method characterized by this.

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