Split contact tip

Abstract

To provide a contact tip which is hardly worn even when used for aluminum welding and to which spatters are hardly stuck.SOLUTION: The split type contact tip is formed by screwing a tip 20 made of nickel silicon copper to the tip of an adapter 10 made of copper alloy. It is preferable that the copper alloy constituting the adapter 10 is chromium copper or zirconium chromium copper, and the nickel silicon copper constituting the distal end tip 20 has a composition of nickel: 1.0 to 5.0% (mass%, the same applies hereinafter), silicon: 0.4 to 2.0%, and the balance: copper and inevitable impurities.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a split contact tip used in arc welding using a welding wire, and particularly to a split contact tip suitable for welding aluminum materials. [Background technology]

[0002] A contact tip for arc welding has a tip body made of a copper alloy with excellent conductivity and a wire insertion hole formed in the center. The welding wire is guided through the wire insertion hole and is supplied with welding current by contact with the inner surface of the wire insertion hole. The tip of the contact tip is exposed to high temperatures caused by the arc and wears due to contact with the welding wire, expanding the hole diameter and easily resulting in a deterioration in weld quality. For this reason, welding operations must be stopped at regular intervals and the contact tip replaced.

[0003] To address this issue, a split contact tip has been proposed, in which a tip made of ceramic or conductive glass is attached to the tip of a copper alloy tip body, as shown in Patent Document 1. However, this structure is complex and expensive, and there is a risk of cracks occurring in the tip due to the large difference in thermal expansion coefficients between metal and ceramic.

[0004] As described in Patent Document 1, conventional contact tips for arc welding are made of copper alloys, which have excellent electrical conductivity. For example, the electrical conductivity of zirco-chromium copper, which is currently commonly used, is IACS 81%. Contact tips made of such copper alloys are widely used for welding steel materials such as automobile bodies.

[0005] However, when conventional copper alloy contact tips are used to weld aluminum, they suffer from severe tip wear and a shortened service life. Because an oxide film quickly forms on the weld surface during aluminum welding, it is necessary to switch the welding current between AC and DC to remove the oxide film. This switching of the welding current is thought to be one of the causes of increased tip wear. Furthermore, aluminum welding is prone to spatter, and when copper alloy contact tips are used to weld aluminum, aluminum spatter adheres to the tip body, making removal difficult. Because aluminum welding is particularly important in the field of electric vehicles, there is a need for the development of contact tips suitable for aluminum welding. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Utility Model Registration No. 3227420 Summary of the Invention [Problem to be solved by the invention]

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a contact tip which overcomes the above-mentioned conventional problems, is less susceptible to wear when used in aluminum welding, and is less susceptible to spatter adhesion. [Means for solving the problem]

[0008] As a result of extensive research into solving the above problems, the inventors have discovered that when welding aluminum materials, it is necessary to select a material that has low thermal conductivity and is less susceptible to aluminum spatter adhesion, even if it suppresses the electrical conductivity that has traditionally been emphasized.

[0009] The present invention was made based on the above findings, and is characterized in that a tip made of nickel silicon copper is screwed onto the tip of a copper alloy adapter.

[0010] The copper alloy constituting the adapter is preferably chromium copper or zircochromium copper, and the nickel silicon copper constituting the tip preferably has a composition of nickel: 1.0 to 5.0% (mass %, the same applies hereinafter), silicon: 0.4 to 2.0%, and the balance: copper and unavoidable impurities. [Effects of the Invention]

[0011] The contact tip of the present invention has a split structure in which a tip made of nickel silicon copper is screwed onto the tip of a copper alloy adapter. Nickel silicon copper has a significantly lower thermal conductivity than chromium copper or zircochromium copper, which allows for arc concentration and improved bead shape. Furthermore, nickel silicon copper has increased hardness due to the nickel silicon precipitate phase, which reduces wear. Furthermore, aluminum spatter is less likely to adhere, and even if it does adhere, it is easy to remove. Therefore, when used to weld aluminum materials, it is estimated that the service life will be extended by more than five times compared to conventional copper alloy contact tips. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is an exploded cross-sectional view of the split contact tip of the embodiment. [Figure 2] FIG. 2 is a plan view of the split contact tip of the embodiment. [Figure 3] FIG. 10 is a plan view of a split contact tip according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] An embodiment of the present invention will be described below. As shown in the exploded cross-sectional view of Figure 1, the split contact tip of the present invention consists of an adapter 10 and a tip tip 20. A wire insertion hole 21 is formed in the center of the tip tip 20, and a male thread portion 22 is formed at the rear end. A female thread portion 11 into which the male thread portion 22 of the tip tip 20 is threaded is formed at the tip end of the adapter 10, and a wire insertion hole 12 is formed at the center of the adapter 10. A male thread portion 13 is also formed at the rear end of the adapter 10. During use, the tip tip 20 is threaded onto the tip of the adapter 10 and connected to the tip of the tip body 30 as shown in Figure 2. A flat portion 23 for tool engagement is formed on the surface of the tip tip 20, and a flat portion 14 for tool engagement is also formed on the surface of the adapter 10.

[0014] Currently, contact tips with a total length of 40 mm or 45 mm are widely used in Japan, so in this embodiment, the length of the tip 20 is a fixed length of 28 mm, and the adapter 10 comes in two lengths, 20 mm and 25 mm, so that the total length of the split contact tip can be adjusted to 40 mm or 45 mm, as shown in Figures 2 and 3.

[0015] The material of the adapter 10 is a conventional copper alloy with excellent conductivity, and in this embodiment, it is zirco-chromium copper, which is easily available. As mentioned above, the conductivity of zirco-chromium copper is 81% IACS, providing excellent conductivity. In contrast, the material of the distal tip 20 is nickel-silicon copper.

[0016] Nickel silicon copper is a copper alloy in which nickel and silicon are added to copper, and a particularly preferred composition is nickel: 1.0 to 5.0% (mass %, the same applies below), silicon: 0.4 to 2.0%, and the remainder: copper and unavoidable impurities. Nickel silicon copper with this composition has a conductivity of 47% IACS, which is lower than that of zircochromium copper, and therefore it is believed that it has never been used as a material for contact tip bodies.

[0017] Nickel-silicon copper with this composition also has low thermal conductivity, at 180 W / (m·K), roughly half the values ​​of 335 W / (m·K) for chromium copper and 332 W / (m·K) for zirco-chromium copper. Because of this low thermal conductivity, its use in the tip 20 concentrates the arc, improving the bead shape and making it suitable for aluminum welding. The welding wire is energized through the copper alloy adapter 10, and it has been confirmed that even with a conductivity of 47% IACS for the tip 20, there is no problem with the passage of the welding current.

[0018] Nickel-silicon copper with this composition has increased hardness due to the nickel-silicon precipitate phase occurring in the copper matrix, which can suppress wear. Furthermore, age hardening due to arc heat can further increase hardness. In particular, by changing the manufacturing method of the tip 20 from the conventional cutting process to a forging process, the hardness is increased by forging hardening, achieving a high hardness of HV250, which is expected to have a wear suppression effect.

[0019] Furthermore, nickel silicon copper with this composition is resistant to spatter adhesion, similar to beryllium copper, and even if spatter does adhere, it can be easily removed. For these reasons, the split contact tip of the present invention is ideal for welding aluminum materials, which requires switching between AC and DC welding currents, and is expected to have a service life five times longer than that of conventional contact tips made of zircochromium copper.

[0020] Next, we will explain why a composition of 1.0-5.0% nickel, 0.4-2.0% silicon, and the remainder copper and unavoidable impurities is preferable. If the nickel content is less than 1.0%, the nickel-silicon precipitate phase is reduced, resulting in a decrease in hardness and increased abrasion resistance. Conversely, if the nickel content exceeds 5.0%, the hardness increases but the conductivity decreases. Furthermore, if the silicon content is less than 0.4%, the hardness also decreases and the material becomes more abrasive. Conversely, if the silicon content exceeds 2.0%, the heat resistance decreases. Thus, nickel and silicon are components that contribute to improving hardness and abrasion resistance, but also inhibit conductivity and heat resistance. Therefore, the above-mentioned composition range is considered to be the most balanced composition for the material of the tip 20 for aluminum welding. Copper alloys contain trace amounts of unavoidable impurities, which may inhibit properties such as hardness, heat resistance, and conductivity. Therefore, the total amount of these impurities is preferably 0.3% or less.

[0021] Next, the results of aluminum welding using the split contact tip of the above-described embodiment are shown. Nickel-silicon-copper wire having a composition of 3.0% nickel, 0.9% silicon, and the remainder copper and unavoidable impurities was cut, and then forged, threaded by rolling, and drilled to produce a 28 mm long tip 20. The diameter of the welding wire made of aluminum material for aluminum welding was 1.2 mm, and the inner diameter of the wire insertion hole 21 was 1.5 mm. This tip 20 was screwed onto the tip of a zirco-chromium copper adapter 10 to produce a split contact tip with a total length of 45 mm.

[0022] Using this split contact tip, aluminum welding was performed by periodically switching the welding current between DC and AC. For comparison, aluminum welding was also performed using a conventional one-piece contact tip made of zirco-chromium copper.

[0023] As a result, it was confirmed that the split contact tip of the present invention has less wear and its service life is at least five times longer than that of a conventional one-piece contact tip made of zirco-chromium copper. In addition, tests were conducted by changing the type of welding wire to copper-plated wire, low-slag wire, no-plated wire, SUS wire, etc., and regardless of the welding wire used, the service life was at least five times longer than that of a conventional one-piece contact tip made of zirco-chromium copper.

[0024] Furthermore, although aluminum welding generates aluminum spatter, it is difficult for it to adhere to the surface of the tip 20 of the split contact tip of the present invention, and even if it does adhere, it can be easily removed by wiping it off.

[0025] As described above, by using the split contact tip of the present invention, aluminum welding, which has been considered more difficult than welding steel, can be performed easily and economically. [Explanation of symbols]

[0026] 10 Adapters 11 Female thread 12 Wire insertion hole 13 Male thread 14 Tool locking flats 20 Tip 21 Wire insertion hole 22 Male thread 23 Flat part for tool locking 30 Tip Body

Claims

1. A split contact tip characterized by a tip tip made of nickel silicon copper screwed onto the tip of a copper alloy adapter.

2. 2. The split contact tip according to claim 1, wherein the copper alloy constituting the adapter is chromium copper or zirco-chromium copper.

3. The split contact tip according to claim 1 or 2, characterized in that the nickel silicon copper constituting the tip has a composition of nickel: 1.0 to 5.0% (mass %, the same applies below), silicon: 0.4 to 2.0%, and the remainder: copper and unavoidable impurities.

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