WO2004096468A1

WO2004096468A1 - Composite rod and production method therefor and arc welding contact tip and resistance welding electrode comprising the composite rod

Info

Publication number: WO2004096468A1
Application number: PCT/JP2003/005496
Authority: WO
Inventors: Tsuyoshi Isejima
Original assignee: Kansai Pipe Industries, Ltd.
Priority date: 2003-04-30
Filing date: 2003-04-30
Publication date: 2004-11-11
Also published as: AU2003235977A1; JPWO2004096468A1

Abstract

A composite rod which is suitably used as an arc welding contact tip and a resistance welding electrode material, and is formed by inserting a core material having a dispersion-strengthened copper alloy section at at least the inner side portion thereof excluding a outer skin portion into an outer tube material consisting of copper or copper alloy and drawing them together, a ratio between the diameter of the whole rod and that of the dispersion-strengthened copper alloy section being 0.1-0.49. In this composite rod, a proportion accounted for by the dispersion-strengthened copper alloy section can be minimized while still retaining a performance required when the rod is worked into an arc welding contact tip or a resistance welding electrode, thereby enabling a significant cost reduction compared to a conventional aluminum dispersed copper rod.

Description

Specification

TECHNICAL FIELD The present invention relates to a composite rod, a method for producing the same, a contact tip for arc welding comprising the composite rod, and an electrode for resistance welding.

The present invention relates to a composite rod having excellent conductivity, heat resistance, abrasion resistance and welding resistance, and particularly suitably used as a conductive material such as a contact tip for arc welding and an electrode for resistance welding. Background art

Contact tip materials used in arc welding such as MIG welding and MAG welding are required to have electrical conductivity and heat resistance, and copper alloys such as chromium copper, zirconium copper, and zirconium chromium copper are generally used to meet these requirements. I have been. Also, as for the material of the electrode used for resistance welding such as spot welding, since conductivity and heat resistance are required, chromium copper, diconium copper, zirconium chromium copper, etc., as in the case of the contact tip, are also used. Has been used.

However, with the improvement of productivity and diversification of materials to be welded, the use conditions of contact tips and electrodes have become more severe, and the conventional ones made of the above-mentioned copper alloy have problems such as wear resistance and welding resistance. , It has become impossible to obtain satisfactory results.

Thus, in recent years, alumina dispersion strengthened copper has been used as a material for contact chips and electrodes. Alumina dispersion strengthened copper is obtained by dispersing fine particles of alumina in a copper matrix, and is usually formed by an internal oxidation method. In the case of a contact chip or an electrode, it is generally manufactured by first forming an alumina dispersion strengthened copper rod and subjecting it to the required processing. When producing alumina-dispersed copper, the diffusion rate of oxygen in the copper matrix is low.If copper, which is a matrix, is formed into a rod and then subjected to internal oxidation treatment, the entire rod becomes internal acid. It will take a very long time to convert.

Thus, for example, as disclosed in Japanese Patent Application Laid-Open No. 1-263203, an aluminum-containing copper powder having a large surface area is internally oxidized to produce an alumina-dispersed copper powder, which is then converted from oxygen-free copper. It is common practice to produce an aluminum-dispersed copper alloy rod by encapsulating it in a container and performing hot extrusion.

However, in the case of the above-mentioned alumina-dispersed copper alloy rod, there is a problem that productivity is low and manufacturing cost is high.

An object of the present invention is to provide a rod which is suitably used as a material for an arc welding contact tip, a resistance welding electrode, or the like at a lower cost. Disclosure of the invention

In the case of a conventional alumina-dispersed copper rod, an oxygen-free copper portion is formed on the outer skin portion, and an alumina-dispersed copper alloy portion is formed on the remaining inner portion. Japanese Patent Application Laid-Open No. Hei 1-263203 discloses that the ratio of the diameter of the alumina-dispersed copper alloy portion to the diameter of the entire rod is 0.5 to 0.94.

However, the contact tip electrode usually needs to be made of an alumina-dispersed copper alloy having excellent wear resistance, welding resistance, etc., only at the inner central portion.

Further, in the conventional alumina-dispersed copper rod, the proportion occupied by the alumina-dispersed copper alloy part cannot be reduced so much due to its manufacturing method, and the ratio of the diameter of the alumina-dispersed copper alloy part to the diameter of the entire rod is 0. In fact, it is about 4 or slightly larger. '

Therefore, the present inventors have focused on research and development of a composite rod that can minimize the proportion occupied by the dispersion-strengthened copper alloy portion, and have reached the present invention.

That is, in the composite rod according to the present invention, a core material having a dispersive copper alloy part at least on the inner part excluding the outer skin part is inserted into an outer pipe material made of copper or a copper alloy, and these are drawn. The ratio of the diameter of the dispersion-strengthened copper alloy portion to the diameter of the entire rod is 0.1 to 0.49.

In the composite rod composed of the above-mentioned core material and outer tube material, If the ratio of the diameter of the copper oxide alloy portion is less than 0.1, the intended performance may not be exhibited when it is processed into a contact tip for arc welding and an electrode for resistance welding. When the above ratio is larger than 0.49, the ratio of the dispersion-strengthened copper alloy part occupies the same area even if the performance when processed into a contact tip for arc welding or an electrode for resistance welding does not change. Increases the cost. The ratio is more preferably between 0.15 and 0.4.

Therefore, according to the composite rod of the present invention, the proportion occupied by the dispersion-strengthened copper alloy portion is within a range capable of maintaining the performance required when processed into an arc welding contact tip or a resistance welding electrode. Since it has been minimized, the cost can be greatly reduced compared to conventional alumina-dispersed copper alloy rods.

In the composite rod according to the present invention, the dispersion-strengthened copper alloy portion is, for example, at least one oxide selected from the group consisting of alumina, zirconia, thoria, yttria, beryllia, and polonia dispersed in a copper matrix. . These oxides are harder than the matrix copper and have lower oxide formation energy. It is possible to obtain a dispersion-strengthened copper alloy having similar properties by dispersing boride and carbide in addition to oxides in a copper matrix. .

In the above case, the amount of the oxide in the dispersion strengthened copper alloy part is preferably 0.15 to 1% by mass. If the amount of the oxide is less than 0.15% by mass, the strength is insufficient. If the amount of the oxide is more than 1% by mass, machining such as cutting and forging becomes difficult.

In the composite rod according to the present invention, the core material is usually formed by encapsulating the dispersion-strengthened copper alloy powder obtained by the internal oxidation method in a container made of copper or a copper alloy and subjecting them to hot extrusion. The dispersion-strengthened copper alloy portion is formed on the inner portion of the core material excluding the outer skin portion made of copper or a copper alloy. As the copper or copper alloy constituting the container, for example, oxygen-free copper, copper oxide, chromium copper, zirconium copper, zirconium chromium copper, or the like is used, and this is used as the outer shell of the core material.

In the composite rod according to the present invention, the outer tube material is usually one of pure copper (oxygen-free copper, phosphorous deoxidized copper, etc.), chromium copper, zirconium copper, and zirconium chromium copper. Of ingots.

The present invention also includes a method for producing the composite rod. This manufacturing method is based on a method in which a dispersion-strengthened copper alloy powder obtained by an internal oxidation method is sealed in a container made of copper or a copper alloy, and the core material formed by hot-extrusion of the powder is converted into a copper or copper alloy. Injecting into the outer tube material made of the ingot material and drawing them out. According to the above manufacturing method, a composite rod in which the proportion occupied by the dispersion-strengthened copper alloy portion is minimized can be easily obtained.

In the method for manufacturing a composite rod according to the present invention, it is preferable to perform annealing in order to metal-bond the interface between the drawn core material and the outer tube material.

In the above case, annealing is preferably performed in a vacuum or a weak reducing atmosphere at 400 to 700 ° C. for 0.25 to 24 hours. Further, it is preferable to start annealing when the degree of drawing becomes 20% or more.

In the method of manufacturing a composite rod according to the present invention, the material of the container and the outer pipe material may be the same.

In the above case, the bonding strength at the interface between the drawn core material and the outer tube material increases, and the properties of the parts other than the dispersion strengthened copper alloy after annealing become uniform, which is advantageous for processing such as forging. It is.

The present invention includes a contact tip for arc welding formed from the composite rod.

A contact tip is usually formed by cutting a rod, which is a material, into a desired external shape and opening a hole in the center. Since a welding wire is passed through these pores and energized, there is a possibility that the surroundings of the pores may be changed due to wear and spatter. In the case of the contact tip according to the present invention, only the periphery of the pores is formed from the dispersion-strengthened copper alloy portion that is unlikely to undergo the above-mentioned deterioration. Therefore, according to the contact tip of the present invention, despite having the same conductivity, heat resistance and wear resistance as the conventional contact tip formed from the alumina-dispersed copper alloy rod, , Can significantly reduce costs.

Further, the present invention includes an electrode for resistance welding formed from the composite rod. The electrodes are usually formed by subjecting the material rod to the required forging and Z or cutting. In particular, the electrodes used in automobile assembly lines, etc., are tapered at the tip in order to improve current strength and pressure, and this tip is most likely to be worn during welding. In the case of the contact tip according to the present invention, only the tip portion is formed from the dispersion-strengthened copper alloy portion that is unlikely to cause the above-described wear. Therefore, according to the electrode for resistance welding of the present invention, both weldability and cost can be achieved. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view of a core material and an outer pipe material used as a material of a composite rod according to the present invention.

FIG. 2 is a cross-sectional view of a composite rod according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

(Example 1)

A Cu 0.3 mass% A1 alloy powder having an average particle size of 50 m was produced by a water atomizing method. To this Cu—A1 alloy powder, a cuprous oxide powder having an average particle size of 5 m was mixed so as to correspond to a stoichiometric amount for oxidizing the aluminum. Then, the obtained mixed powder was heated and maintained at 850 ^ for 8 hours in an argon gas atmosphere, and further heated and maintained at 50,000 for 3 hours in a hydrogen gas atmosphere. Thus, an alumina dispersion-strengthened copper powder in which alumina was dispersed in a copper matrix was produced.

Next, the alumina dispersion-strengthened copper powder was sealed in a cylindrical container with a lid made of oxygen-free copper having an outer diameter of 25 O mm and an inner diameter of 25 mm, and was subjected to underwater extrusion at 800 to a diameter of 3 O mm. This was further drawn to obtain a rod-shaped core material having a diameter of 6.5 mm. As shown in Fig. 1 (a), the core material (1) has an oxygen-free body (2) on its outer surface, and the remaining inner portion is made of an alumina dispersion strengthened copper alloy (3). The alumina content in the alumina dispersion strengthened copper alloy part (3) was about 0.5 mass%.

Separately, a zirconium chromium copper alloy was melted and formed, and the resulting ingot was subjected to hot extrusion, rolling, and drawing to produce an outer tube material (4) having an outer diameter of 25 mm and an inner diameter of 7 mm. (See Figure 1 (b)). After inserting the core material (1) into the outer pipe material (4) and drawing them out to a diameter of 12 mm, they are placed in a weak reducing gas atmosphere (inert gas containing 4% H + CO) at 500 ° C. Annealed for 1 hour. Thus, a composite rod (5) as shown in FIG. 2 was obtained.

In the above composite rod (5), the alumina dispersion strengthened copper alloy part (20) has a diameter (B) of 3 mm, and is 25% of the entire outer diameter (A) (12 mm) of the rod (5). Account for the percentage of A zirconium chromium copper part (40) is formed around the alumina dispersed high strength copper alloy part (20) via an oxygen-free copper part (30) with a thickness of 2 mm.

(Comparative Example 1)

The same alumina-dispersed strong copper powder produced in the process of Example 1 was sealed in a cylindrical container with a lid made of oxygen-free copper having an outer diameter of 25 Omm and an inner diameter of 235 mm, and was extruded underwater to a diameter of 3 Omm at 800. This was further processed and drawn to obtain an alumina dispersion strengthened copper rod having a diameter of 12 mm.

In the above alumina dispersion strengthened copper rod, the diameter of the alumina dispersion strengthened copper alloy part is 11.3 mm, which accounts for 94% of the outer diameter (12 mm) of the entire rod.

When the manufacturing costs of the composite rod (5) of Example 1 and the alumina dispersion-strengthened copper rod of Comparative Example 1 were calculated and compared, the cost of Example 1 was only about half that of Comparative Example 1. Did not.

The electrical conductivity and the hardness of the composite rod (5) of Example 1 and the alumina dispersion-strengthened copper rod of Comparative Example 1 were measured.

The electrical conductivity of the composite rod (5) of Example 1 was 80% ACS in the alumina dispersion strengthened copper alloy part. The hardness of the composite rod (5) was 165 HV in the alumina dispersion strengthened copper alloy part (20) and 17 OHV in the zirconium chromium copper part (40).

On the other hand, the conductivity of the alumina dispersion strengthened copper rod of Comparative Example 1 was 80% ACS in the alumina dispersion strengthened copper alloy part. The hardness of the rod was 165 HV in the alumina dispersion strengthened copper alloy part and 90 HV in the oxygen-free copper part of the outer skin.

As is clear from the above, the composite rod (5) according to the present invention (Example 1) is a Despite having the same excellent electrical conductivity and abrasion resistance as the luminous dispersion strengthened copper rod (Comparative Example 1), it can be manufactured at about one-half the cost.

(Example 2)

The composite rod (5) produced in Example 1 was subjected to required cutting, and a hole having a diameter of 1.2 mm was drilled at the center thereof to produce a contact tip for MIG welding.

(Comparative Example 2)

The alumina dispersion strengthened copper rod produced in Comparative Example 1 was subjected to the same cutting and drilling as in Example 2 to produce a contact tip for MIG welding.

(Comparative Example 3)

A 12 mm diameter rod made of ingot material of zirconium chromium copper was subjected to the same cutting and drilling processes as in Example 2 to produce a contact tip for MIG welding. Contacts of Example 2 and Comparative Examples 2 and 3 We measured the welding life (time allowed for continuous welding) when MIG welding mild steel sheets using the tip. The evaluation was performed by rotating a drum made of a mild steel plate (thickness: 5 mm) and placing a bead while moving the torch little by little in the length direction of the drum, until the excess was not continuously formed. Time.

The welding life when the contact tip of Example 2 was used was almost the same as that when the contact tip of Comparative Example 2 was used, and was about 4 times the welding life when the contact tip of Comparative Example 3 was used. It was twice.

(Example 3)

A composite rod (5) having a diameter of 16 mm (diameter of the alumina dispersion strengthened alloy part: 7 mm) produced in the same manner as in Example 1 was forged and cut into a required shape to produce an electrode for resistance spot welding. The electrode shape was a CR (dom) shape, and the diameter of the flat part at the tip was 5 mm.

(Comparative Example 4)

An alumina dispersion strengthened copper rod having a diameter of 16 mm (diameter of the alumina dispersion strengthened alloy part: 15 mm) manufactured in the same manner as in Comparative Example 1 was processed in the same manner as in Example 3 to form an electrode for resistance spot welding. Was prepared. (Comparative Example 5)

A rod having a diameter of 16 mm made of ingot material of zirconium chromium copper was subjected to the same cutting processing as in Example 3 to produce an electrode for resistance spot welding.

Using the electrodes of Example 3 and Comparative Examples 4 and 5, the electrode life (number of spots) when spot welding of a zinc plated steel sheet was performed was measured. The evaluation was performed with the number of spots for which the nugget (melted part) diameter was less than 4 t (t = plate thickness) for the first time.

The electrode life when the electrode of Example 3 was used was almost the same as that when the electrode of Comparative Example 4 was used, and was about 2.5 times the electrode life when the electrode of Comparative Example 5 was used. Was.

(Example 4)

A composite rod was produced in the same manner as in Example 1, except that the material of the container was the same zirconium chromium copper alloy as the outer tube material. Then, the composite rod was subjected to forging and cutting in the same manner as in Example 3 to produce an electrode for resistance spot welding.

Comparing the workability of the composite rod in Example 4 with that of Example 3, the processing of the composite rod, particularly forging, was easier in Example 4. Industrial applicability

As described above, the present invention provides a composite rod having a minimum required dispersion-strengthened copper alloy part. In particular, the present invention provides a conventional rod as a conductive material such as a contact tip for arc welding and an electrode for resistance welding. Despite having the same high performance as alumina-dispersed copper rod, it is useful in that it can be supplied at low cost.

Claims

The scope of the claims

1. A core material having a dispersion-strengthened copper alloy part at least on the inner part excluding the outer skin part is inserted into an outer pipe made of copper or a copper alloy, and these are formed by drawing. A composite rod, wherein the ratio of the diameter of the dispersion-strengthened copper alloy part to the diameter of the copper rod is 0.1 to 0.49.

2. The composite rod according to claim 1, wherein the ratio of the diameter of the dispersion-strengthened copper alloy part to the diameter of the entire rod is 0.15 to 0.4.

3. The composite according to claim 1, wherein the dispersion-strengthened copper alloy part is obtained by dispersing an oxide of at least one of alumina, zirconia, tria, yttria, beryllia, and polonia in a copper matrix. rod.

4. The composite rod according to claim 3, wherein the amount of the oxide in the dispersion-strengthened copper alloy part is 0.15 to 1% by mass.

5. The core material is formed by encapsulating the dispersion-strengthened copper alloy powder obtained by the internal oxidation method in a container made of copper or copper alloy and subjecting them to hot extrusion.

The composite rod according to any one of claims 1 to 4, wherein the dispersion-strengthened copper alloy portion is formed on an inner portion of the core material excluding an outer skin portion made of copper or a copper alloy.

6. The composite rod according to any one of claims 1 to 5, wherein the outer pipe is made of a smelted material of any one of pure copper, chromium copper, zirconium copper, and zirconium chromium copper.

7. The method for producing a composite rod according to claim 1, wherein the dispersion-hardened copper alloy powder obtained by the internal oxidation method is enclosed in a container made of copper or a copper alloy, and these are subjected to hot extrusion. A method of manufacturing a composite rod, wherein the core material formed as described above is introduced into an outer tube material made of ingot material of copper or a copper alloy, and is drawn.

8. The method for producing a composite rod according to claim 7, wherein annealing is performed to metal-bond the interface between the drawn core material and the outer tube material.

9. The method of manufacturing a composite rod according to claim 8, wherein the annealing is performed in a vacuum or a weak reducing atmosphere at a temperature of 400 to 700 for 0.25 to 24 hours.

10. The method according to claim 8, wherein the annealing is started when the bow I punching degree reaches 20% or more. Or the method for producing a composite rod according to item 9.

11. The method for producing a composite rod according to claim 8, wherein the material of the container and the outer pipe material are the same.

12. A contact tip for arc welding, formed from the composite rod according to claim 1.

13. An electrode for resistance welding formed from the composite rod according to claim 1.