Contact tube for welding

Abstract

According to the contact tip for welding, the whole contact tip main body is made of a copper alloy with components including, in mass%, 1.0-5.0% of Ni, 0.4-2.0% of Si, and the balance Cu and unavoidable impurities. The manufacturing cost can be restrained, and the service life can be prolonged to 6-8 times of that of the prior art. In addition, it is preferable that the total amount of unavoidable impurities is 0.3% or less. In addition, it is particularly preferable that Ni: 2.0-4.0%, and Si: 0.8-1.5%.

Description

TECHNICAL FIELD

[0001] The present application relates to an electrically conductive nozzle for welding, which has a function of guiding a wire for welding and supplying a welding current to the wire for welding. BACKGROUND

[0002] The electrically conductive nozzle for welding is formed with a wire insertion hole in a center portion of a rod-shaped electrically conductive nozzle body composed of a copper alloy excellent in electrical conductivity, guides the wire for welding by the wire insertion hole, and supplies a welding current by contact with an inner wall surface of the wire insertion hole. The tip portion of the electrically conductive nozzle for welding is easily abraded by contact with the wire for welding on the basis of exposure to high temperature caused by an arc, thereby causing an increase in hole diameter and easily causing a decrease in welding quality. Therefore, it is necessary to replace the electrically conductive nozzle for welding at regular intervals, and it is necessary to stop welding work during this period.

[0003] Therefore, there is a strong demand for the electrically conductive nozzle for welding to have excellent abrasion resistance and a long service life, and various studies have been made in the past. For example, Patent Literature 1 describes an electrically conductive nozzle for welding in which a ceramic material cylindrical body is embedded in the tip portion of the wire insertion hole to improve abrasion resistance. In addition, Patent Literature 2 describes an electrically conductive nozzle for welding in which a nickel-boron plated film and a coating layer of a lubricant are formed on the surface of the inner surface of the wire insertion hole to improve abrasion resistance. However, these structures require special processing, and therefore, there is a problem of an increase in manufacturing cost.

[0004] Therefore, as shown in Patent Literature 3, studies have also been made on the material of the copper alloy constituting the electrically conductive nozzle for welding. In this Patent Literature 3, the copper alloy contains 0.03 to 0.7% of silver, and drawing processing and cold processing are performed, thereby improving the hardness and electrical conductivity of the electrically conductive nozzle for welding. However, since silver, which is expensive, is used, there is a problem of an increase in manufacturing cost. The electrically conductive nozzle for welding is a consumable product, and therefore, the cost problem cannot be ignored for the user.

[0005] In addition, in recent years, welding in which the polarity of a welding current is periodically switched has become mainstream, and in this case, the tip hole diameter of the wire insertion hole is easily further increased.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Laid-Open No. 10-193122

[0009] Patent Literature 2: Japanese Patent Application Laid-Open No. 2017-189816

[0010] Patent Literature 3: Japanese Patent Application Laid-Open No. 2009-90355 SUMMARY

[0011] The present application has an object to provide a welding electrode tip which suppresses manufacturing cost and greatly improves service life compared with the past.

[0012] The welding electrode tip of the present application, which has been achieved to solve the above problem, is characterized in that the electrode tip body is composed of a copper alloy having components of Ni: 1.0 to 5.0%, Si: 0.4 to 2.0%, and the remainder: Cu and inevitable impurities, in mass%.

[0013] Further, it is preferable that the total amount of the inevitable impurities is 0.3% or less. In addition, it is particularly preferable that the range of Ni: 2.0 to 4.0%, Si: 0.8 to 1.5%.

[0014] Effects of the Invention

[0015] The welding electrode tip of the present application can balance the electrical conductivity and the wear resistance by setting the content of Ni and Si to the above range, and as a result, it is possible to successfully suppress the manufacturing cost and greatly improve the service life compared with the past. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a cross-sectional view of the welding electrode tip of the embodiment. DETAILED DESCRIPTION

[0017] The embodiment of the present application will be described in detail below.

[0018] Figure 1 is a cross-sectional view of the welding electrode tip of the embodiment, a through hole 11 of a welding wire is formed in the center of a cylindrical electrode tip body 10, and an external thread portion 12 is formed in the rear end. The rear end of the through hole 11 is formed into a tapered wire introduction portion 13. The electrode tip body 10 is composed of a copper alloy having components of Ni: 1.0 to 5.0%, Si: 0.4 to 2.0%, and the remainder: Cu and inevitable impurities.

[0019] Ni is easily alloyed with copper, and has a higher hardness than copper, and thus, Ni is a component which contributes to the improvement of the wear resistance. In addition, Si also functions as a surfactant to promote the intermetallic bonding, and has a higher hardness than copper, and thus, Si is a component which contributes to the improvement of the wear resistance. Therefore, the welding electrode tip of the present application composed of the copper alloy containing Ni and Si can suppress the breakage due to the wear and prolong the service life in welding with a fast wire feeding speed or in welding with a large degree of wear.

[0020] However, on the other hand, the conductivity of Ni and Si is lower than that of copper. Therefore, increasing their content will decrease the conductivity of the welding contact tip, leading to increased heat generation, scorching of the contact tip, and a decrease in welding quality. Furthermore, Si has poorer heat resistance than copper. Therefore, increasing its content may cause the welding contact tip to soften or melt due to high temperatures.

[0021] Thus, while Ni and Si contribute to improved wear resistance, they also hinder conductivity and heat resistance. Therefore, the inventors of this invention conducted repeated experiments and determined that a composition of Ni: 1.0–5.0%, Si: 0.4–2.0%, with the remainder being Cu and unavoidable impurities, is the optimal balance that can be achieved as a conductive tip for welding.

[0022] That is, if Ni is less than 1.0%, the hardness decreases; if it exceeds 5.0%, the hardness increases, but this leads to a decrease in electrical conductivity and heat resistance. Similarly, if Si is less than 0.4%, the hardness decreases; if it exceeds 2.0%, this leads to a decrease in electrical conductivity and heat resistance. In particular, the range of Ni: 2.0–4.0% and Si: 0.8–1.5% in the middle of the above ranges is the most preferred range.

[0023] Furthermore, copper alloys contain trace amounts of unavoidable impurities, which hinder conductivity; therefore, their total amount is preferably set to 0.3% or less. Additionally, there are copper alloys with added hard metals such as chromium and cobalt to increase hardness, but these all lead to a decrease in conductivity and become a major cause of increased cost. Therefore, they are not preferred materials for conductive tips used in welding.

[0024] The following shows the results of experiments conducted to confirm the performance of the present invention.

[0025] As shown in Table 1, a welding contact tip was made from a copper alloy wire with altered Ni and Si compositions. Additionally, for comparison, conventionally used chromium-copper contact tips and silver-containing copper contact tips as shown in Patent Document 3 were prepared. These were placed on a physical machine and subjected to periodically switching welding currents in both forward and reverse phases, and service life data were collected. The percentages in Table 1 are by mass, with the remainder being copper and unavoidable impurities.

[0026] Regarding the measurement of service life, stainless steel wire was used as the welding wire, and the service life of a chrome-copper conductive tip was used as the standard. Service life of equal quality was rated as ○, service life below that was rated as ×, and service life above that was rated as ◎. Furthermore, the service life of the conductive tips of products No. 2, 3, and 6 of this invention is 6 to 8 times that of the standard products, representing a significant extension compared to existing products. When using both unplated and plated wires as welding wire, the service life of the welding conductive tips of No. 2, 3, and 6 was also confirmed to be 6 to 8 times that of the standard products. The evaluation results are shown in Table 1.

[0027] Table 1

[0028]

[0029] As shown in Table 1, the welding conductive tips No. 2, 3, and 6, which are products of this invention, have excellent conductivity, low cost, and significantly improved service life compared with existing chromium copper welding conductive tips.

[0030] Regarding the No.1 welding contact tip, the Ni and Si content is low, and all evaluation items except conductivity are marked as ×. The No.4 has a low Si content; therefore, its service life is equivalent to that of the standard product No.8. The No.5 has an excessively high Si content, resulting in decreased heat resistance and conductivity. The No.7 has an excessively high Ni content, resulting in decreased conductivity. The No.9 silver-containing copper contact tip has performance equivalent to or better than the standard product, but at a higher cost. Furthermore, the high Ni and Si content in No.5 and No.7 indicates a tendency for sputtering particles to adhere.

[0031] As explained above, the welding conductive tip of the present invention can balance conductivity and wear resistance, resulting in reduced manufacturing costs and a leap in service life to 6 to 8 times that of existing products, demonstrating excellent practicality.

[0032] Explanation of reference numerals in the attached figures

[0033] 10 conductive nozzle body

[0034] 11. Through-hole for welding wire

[0035] 12 External thread section

[0036] 13. Wire introduction section.

Claims

1. A conductive tip for welding, characterized in that, The main body of the conductive tip is made of a copper alloy having a composition of Ni: 1.0-5.0%, Si: 0.4-2.0%, Cu, and unavoidable impurities by mass%.

2. The conductive nozzle for welding according to claim 1, characterized in that, The total amount of unavoidable impurities is less than 0.3%.

3. The conductive nozzle for welding according to claim 1, characterized in that, Ni: 2.0 to 4.0%, Si: 0.8 to 1.5%.

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