Contact tip for welding

Abstract

To provide a contact tip for welding capable of supplying a welding current from a tip holder without any trouble while suppressing deformation of a tip part of a wire insertion hole.SOLUTION: A contact tip according to the present invention is formed with a male screw part 13 having a diameter smaller than that of a main body, at a rear end of a main body 10 made of a copper material. On an outer peripheral surface of the main body 10 and an inner peripheral surface of a wire insertion hole 14, a nickel plating layer 30 is formed, and meanwhile, a male screw part 13 and a rear end surface 16 of the main body 10 adjacent thereto are formed as an exposed surface 31 of a copper material, without forming a nickel plating layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a welding contact tip suitable for arc welding. [Background technology]

[0002] A welding contact tip has a body made of a copper material with excellent conductivity, such as copper or a copper alloy, and a wire insertion hole formed in the center of the body to pass a welding wire through. As shown in Patent Document 1, the welding contact tip is used by being screwed and fixed to the tip of a tip holder made of a copper material. A welding current is supplied to the welding contact tip through the tip holder, and further, a current is passed through the welding wire from the inner surface of the wire insertion hole to perform arc welding.

[0003] The wire insertion hole of a welding contact tip is susceptible to wear due to contact with the welding wire, and its tip in particular is subject to high temperatures during arc welding, which can easily cause deformation or enlargement of the hole diameter. Furthermore, spatter generated during welding is likely to adhere to the outer circumferential surface of the welding contact tip. Therefore, as shown in Patent Document 2, a nickel plating layer is formed on the outer circumferential surface of the welding contact tip and the inner circumferential surface of the wire insertion hole, which suppresses deformation of the tip of the wire insertion hole and prevents spatter from adhering to the outer circumferential surface.

[0004] However, in recent years, arc welding has become more common, with the welding current being periodically switched between positive and negative. In this case, deformation of the tip of the wire insertion hole is more likely to occur. To prevent this, attempts have been made to increase the thickness of the nickel plating layer, but this has led to other problems.

[0005] That is, the nickel-plated layer has lower conductivity than the copper material that makes up the main body of the contact tip. Specifically, the IACS% value, which indicates conductivity, is 100% for copper and 70-80% for chromium copper, while it is 24% for nickel. For this reason, contact tips with a thick nickel plating on the entire surface have problems such as increased resistance in the supply path of the welding current from the tip holder, making arc welding unstable and reducing energy efficiency due to excess heat generation. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Utility Model Registration No. 3105620 [Patent Document 2] Japanese Patent Application Publication No. 2019-136768 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to solve the above-mentioned conventional problems and to provide a welding contact tip that can suppress deformation of the tip of the wire insertion hole while allowing welding current to be supplied from the tip holder without any problems. [Means for solving the problem]

[0008] The welding contact tip of the present invention, which has been made to solve the above problems, is a contact tip in which a male thread portion having a diameter smaller than that of the main body is formed at the rear end of the main body made of a copper material, and a nickel plating layer is formed on the outer surface of the main body and the inner surface of the wire insertion hole, and the nickel plating layer is not formed on the male thread portion and the rear end surface of the main body adjacent to this male thread portion, leaving the copper material exposed.

[0009] The nickel plating layer is preferably an electroless nickel plating layer containing chromium.

[0010] It is also preferable that the rear end surface of the main body is a plane perpendicular to the longitudinal axis of the main body. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view showing the appearance of a welding contact tip according to an embodiment of the present invention; [Figure 2] FIG. 2 is a central vertical cross-sectional view of the welding contact tip according to the embodiment. [Figure 3] FIG. 2 is an enlarged schematic cross-sectional view of a main part. [Figure 4] FIG. 10 is a cross-sectional view showing a state in which the main parts are masked. [Figure 5] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present invention will be described below. Fig. 1 is an external perspective view of a welding contact tip according to an embodiment, and Fig. 2 is a central longitudinal cross-sectional view thereof. The body 10 of this welding contact tip is made of a copper material with excellent conductivity, as in the case of conventional welding contact tips. In addition to pure copper, various copper alloys such as chromium copper, chromium zirconium copper, and beryllium copper can also be used as the copper material. Alumina dispersion strengthened copper can also be used.

[0013] The main body 10 consists of a cylindrical portion 11, a tapered tip portion 12, and a male thread portion 13 at the rear end. A wire insertion hole 14 runs through the center of the main body 10. A flat portion 15 is formed at the connection portion of the outer periphery of the cylindrical portion 11 and the tip portion 12. Although only one side is shown in Figure 1, a flat portion 15 is also formed on the opposite side. These flat portions 15 are used as locking portions for tools such as wrenches when attaching the welding contact tip to a tip holder, which will be described later.

[0014] The rear end surface 16 of the cylindrical portion 11 is a plane perpendicular to the longitudinal axis of the main body 10, and has a shape in which an external thread 13, which is smaller in diameter than the cylindrical portion 11, protrudes from the center in the axial direction. This external thread 13 is a part for threading the main body 10 of the welding contact tip into an internal thread formed at the tip of the tip holder 20, as shown in Figure 5. The tip holder 20 is also made of a copper material with excellent conductivity, and is designed so that a welding current is passed through the external thread 13 to the main body 10 of the welding contact tip.

[0015] A nickel plating layer 30 is formed on the outer peripheral surface of the main body 10 and the inner peripheral surface of the wire insertion hole 14. The nickel plating layer 30 formed on the outer peripheral surface of the main body 10 has the effect of preventing adhesion of spatter generated during arc welding, and the nickel plating layer 30 formed on the inner peripheral surface of the wire insertion hole 14 has the effect of preventing wear of the wire insertion hole 14 by the welding wire. To fully exert these effects, it is desirable that the nickel plating layer 30 has excellent adhesion to copper material and high strength, and in this embodiment, an electroless nickel plating layer containing a small amount of chromium is used.

[0016] Unlike iron materials, copper materials have surfaces covered with oxide films, making it difficult to deposit an electroless plating layer on them as is. Therefore, it is preferable to perform a series of pretreatments, such as preliminary degreasing, immersion degreasing, etching, acid activation, and catalytic activation, before electroless nickel plating. A treatment solution containing palladium is used for catalytic activation, and catalytic activation makes it possible to deposit an electroless nickel plating film on the surface of copper materials.

[0017] Alternatively, nickel strike plating can be performed as a base plating after acid activation without the above-mentioned catalytic activation. This involves reducing the oxide film on the copper substrate surface to metal in a strongly acidic bath, resulting in plating with excellent adhesion. By performing either of these pretreatments followed by electroless nickel plating, it is possible to form a strong nickel plating layer 30 on the surface of the copper substrate.

[0018] However, as mentioned above, the IACS% value, which indicates the electrical conductivity of nickel, is 24%, which is about one-fourth that of copper material. Therefore, in the present invention, a nickel plating layer 30 is formed on the outer peripheral surface of the main body 10 and the inner peripheral surface of the wire insertion hole 14, but the nickel plating layer 30 is not formed on the male thread portion 13 and the adjacent rear end surface 16 of the main body 10, leaving an exposed surface 31 where the copper material is exposed. In Figure 1, the exposed surface 31 of the copper material is shown in white, and the nickel plating layer 30 is shown in gray. This is also shown schematically in the cross-sectional view of Figure 3.

[0019] To expose these portions to the copper material as surface 31, a method can be used in which a washer 40 made of an elastic material is fitted onto the male thread portion 13, a nut 41 is screwed on, and the washer is brought into close contact with the rear end surface 16 to create a masking state, as shown in Figure 4, and then the portion is immersed in the plating bath. With this method, the male thread portion 13 and rear end surface 16 are masked and do not come into contact with the nickel plating bath, so the exposed copper material surface 31 can be maintained.

[0020] As shown in Figure 5, the welding contact tip of the present invention is used by threading the male thread portion 13 at the rear end onto the tip of a tip holder 20. In the example of Figure 5, the base of the tip holder 20 is fixed to a nozzle holder 21, which is equipped with a shield nozzle 22 that covers the outer periphery of the tip holder 20 and a tip nozzle 23 that covers the outer periphery of the welding contact tip. A gas supply port 24 is formed in the tip holder 20, and an inert gas such as argon or carbon dioxide gas is supplied from the base of the tip holder 20 and flows into the inside of the shield nozzle 22 and tip nozzle 23, and is sprayed from around the welding contact tip toward the welding point.

[0021] The tip holder 20 and nozzle holder 21 are made of copper, which has excellent conductivity, and the welding current flows through the nozzle holder 21 and tip holder 20 to the main body 10 of the welding contact tip. As described above, in the welding contact tip of the present invention, the male thread portion 13 that screws into the female thread portion at the tip of the tip holder 20 and the rear end face 16 that contacts the tip holder 20's front end face are exposed copper surfaces 31 without a nickel plating layer 30. This allows these surfaces to directly contact the copper material of the tip holder 20 and the copper material of the welding contact tip. Therefore, in the welding contact tip of the present invention, there is no increase in electrical resistance due to the nickel plating layer 30, as occurs in conventional fully plated welding contact tips.

[0022] Furthermore, in the welding contact tip of the present invention, the outer surface of the main body 10 is covered with a nickel plating layer 30, so that spatter generated during arc welding is less likely to adhere to it, and since the nickel plating layer 30 is also formed on the inner surface of the wire insertion hole 14, wear of the wire insertion hole 14 is less likely to occur and deformation of the tip of the wire insertion hole 14 can also be suppressed.

[0023] As described above, the present invention can provide a welding contact tip that can suppress deformation of the tip of the wire insertion hole 14 while allowing welding current to be supplied without hindrance from the tip holder 20. Furthermore, since the nickel plating layer 30 is not present in the current path, there is an advantage that the supply of welding current is not hindered even if the nickel plating layer 30 is made thick. [Explanation of symbols]

[0024] 10 Main Unit 11 Cylinder 12 Tip 13 Male thread 14 Wire insertion hole 15 Flat area 16 Rear end surface 20 Tip holder 21 Nozzle holder 22 Shield Nozzle 23 Tip nozzle 24 Gas supply port 30 Nickel plating layer 31 Exposed copper surface 40 washer 41 Nut

Claims

1. A contact tip having a main body made of copper material and a male thread portion having a diameter smaller than that of the main body formed at the rear end thereof, A nickel plating layer is formed on the outer peripheral surface of the main body and the inner peripheral surface of the wire insertion hole, A welding contact tip characterized in that no nickel plating layer is formed on the male thread portion and the rear end surface of the body adjacent to the male thread portion, leaving the copper material as exposed surfaces.

2. 2. The welding contact tip according to claim 1, wherein the nickel plating layer is an electroless nickel plating layer containing chromium.

3. 3. The welding contact tip according to claim 1, wherein the rear end surface of the body is a plane perpendicular to the longitudinal axis of the body.

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