JP2008223091A - Electrode for welding, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for welding whose wear and deposition can be suppressed while maintaining its strength even if service temperature reaches a high temperature of ≥500°C by performing welding at a high current, and to provide a method for producing the same. <P>SOLUTION: The electrode 2 for welding is formed of an electrode material in which at least one kind of hard grains selected from SiO<SB>2</SB>hard grains, Mo<SB>2</SB>C hard grains and TiC hard grains are dispersed by 0.1 to 2 wt.% in total, and the balance Cu. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a welding electrode and a method for manufacturing the same, and in particular, a welding electrode capable of suppressing wear and welding while maintaining strength even when the operating temperature becomes high temperature of 500 ° C. or higher by welding at a high current. It relates to the manufacturing method.

Hereinafter, a conventional welding electrode will be described.
The following (1) to (4) may be mentioned as the required characteristics of the material for the welding electrode (for example, contact tip, electrode tip, etc.).
(1) A material having high conductivity in order to suppress the chip from generating heat.
(2) A material having high high-temperature strength in order to improve wear resistance and seizure resistance, and to prevent the wire supplied from the contact chip from being stopped.
(3) The material is difficult to adhere to spatter.
(4) The material is difficult to oxidize.

  In particular, as a countermeasure for increasing the high temperature strength of (2) above, a conventional electrode material uses an alloy based on copper to obtain conductivity and thermal conductivity, and the alloy has a high temperature hardness. In order to maintain, metal elements such as chromium and zirconium are contained. The reason why this metal element is contained is to obtain high hardness due to the precipitation effect.

  As a specific example of the conventional electrode tip, chrome copper hardened by the precipitation effect is most widely used. This chromium copper contains 0.3 to 1.2% by mass of Cr in Cu. This Cr creates precipitates by heat treatment and increases the hardness of copper of the electrode (see, for example, Patent Document 1).

JP 2005-111483 A (paragraph 0008)

  By the way, in recent welding, the current has been increasing, and accordingly, the temperature of the welding electrode tends to increase during welding. For example, at high currents exceeding 400 amps, the temperature of the welding electrode may exceed 500 ° C. In the above-described welding electrode made of chromium copper, the required hardness is maintained until the use temperature is about 500 ° C., but when the use temperature exceeds 500 ° C., the chromium copper starts to soften. Once softened, chrome copper will not regain hardness. Therefore, it is vulnerable to repeated heat applied by repeatedly using the welding electrode. For this reason, the welding electrode was worn and welded at an early stage, thereby increasing the frequency of replacement of the welding electrode, resulting in a problem that the facility operation rate was lowered as a whole.

  The present invention has been made in consideration of the above circumstances, and its purpose is to wear and weld while maintaining the strength even when the operating temperature becomes 500 ° C. or higher by welding at a high current. It is providing the welding electrode which can be suppressed, and its manufacturing method.

In order to solve the above-mentioned problems, the welding electrode according to the present invention comprises at least one hard particle of SiO ₂ hard particles, Mo ₂ C hard particles, and TiC hard particles in a total amount of 0.1 wt% to 2 wt%. Dispersed, and the remainder is formed of an electrode material made of Cu.

  In the welding electrode according to the present invention, the electrode material further contains at least one element selected from the group consisting of Zn, Sn, Mn, Al and P, and the upper limit content of Zn Is 0.9 wt%, the upper limit content of Sn is 0.14 wt%, the upper limit content of Mn is 0.1 wt%, and the upper limit content of Al is 0.1 wt% It is preferable that the upper limit content of P is 0.02% by weight.

Further, in the welding electrode according to the present invention, the powder made of the electrode material may be formed and produced by sintering.
In the welding electrode according to the present invention, the kneaded material containing the electrode material may be injection-molded and produced by sintering.

In the method for producing a welding electrode according to the present invention, at least one kind of hard particles among SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles is dispersed in a total amount of 0.1 wt% to 2 wt%, and the balance Is a method of manufacturing a welding electrode made of Cu,
Mixing at least one hard particle powder and Cu powder among SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles;
A step of compacting the mixed powder;
Sintering the green compact molded body at a temperature of 900 ° C. to 1100 ° C .;
It is characterized by comprising.

In the method for producing a welding electrode according to the present invention, at least one kind of hard particles among SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles is dispersed in a total amount of 0.1 wt% to 2 wt%, and the balance Is a method of manufacturing a welding electrode made of Cu,
A step of mixing at least one hard particle powder, Cu powder and binder among SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles;
A step of injection molding the kneaded kneaded product;
Sintering the injection molded molded body at a temperature of 900 ° C. to 1100 ° C .;
It is characterized by comprising.

  In the method for manufacturing a welding electrode according to the present invention, the welding electrode contains at least one element selected from the group consisting of Zn, Sn, Mn, Al, and P, and the mixing step. Then, it is also possible to further mix a powder containing at least one element selected from the group consisting of Zn, Sn, Mn, Al and P.

  As described above, according to the present invention, there is provided a welding electrode capable of suppressing wear and welding while maintaining the strength even when the operating temperature becomes 500 ° C. or higher by welding at a high current, and a method for manufacturing the same. can do.

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a diagram schematically showing welding using a contact tip that is an example of a welding electrode according to Embodiment 1 of the present invention.

  A contact tip 2 is attached to the nozzle 1 of the welding machine, and a hole (not shown) for feeding the welding wire 3 is provided in the contact tip 2. A welding current is supplied to the welding wire 3 by the contact tip 2, and the welding object 4 is welded by accurately supplying the welding wire 3 to a target position. At this time, since a large current flows through the contact chip 2, the temperature of the contact chip 2 becomes high.

The following properties (1) to (5) are preferable as the material of the contact chip 2.
(1) A material having high conductivity in order to suppress heat generation of the chip.
(2) The hardness or strength of the contact chip 2 does not decrease even when heat is repeatedly applied due to use at a high temperature or when the temperature fluctuates. That is, in order to ensure the target property of accurately supplying the welding wire 3 to the target position, the wear resistance at high temperature should be increased and the hole of the contact tip 2 should not be widened.
(3) In order to suppress the supply stop of the welding wire 3, it is difficult to be seized and difficult to be fused.
(4) Spatter is difficult to adhere.
(5) It is difficult to oxidize.

1. Contact Chip Material The contact chip 2 is made of Cu having excellent electrical conductivity as a base material. The base material contains 1% by weight or less of a sintered densified material, and 0.1 to 2% by weight. The hard particles are dispersed. The hard particles do not decrease in hardness even in a temperature range of 600 ° C. to 800 ° C., are resistant to thermal shock, and are more excellent in wear resistance than conventional chromium copper. Abrasion resistance and seizure resistance can be ensured by dispersing hard particles. Incidentally, the lower limit amount of the base material in the material of the contact chip 2 is 97% by weight.

Examples of the hard particles include SiO ₂ , Mo ₂ C, and TiC. One type of these hard particles may be contained in an amount of 1% by weight or less, or a plurality of types of hard particles may be contained in a total of 1% by weight. The reason why SiO ₂ is cited as the hard particles is that it is confirmed that the wear resistance of the sliding material containing 0.5 wt% of SiO ₂ in Cu-10 wt% Sn-10 wt% P is improved. Because. Moreover, Mo ₂ C as hard particles is superior in wear resistance and seizure resistance to Mo and has good non-oil lubrication characteristics. TiC is very excellent in high temperature seizure resistance and wear resistance.

When Cu contains impurities, the electrical conductivity decreases, but the electrical conductivity of the contact chip 2 is preferably 35 m / Ohm · mm ² or more. Here, the electric conductivity of the Cu base material is about 50 m / Ohm · mm ² . Therefore, in order to make the contact chip 2 have an electrical conductivity of 35 m / Ohm · mm ² or more, the maximum addition amount of each element functioning as a sintered densification material to the Cu base material is as shown in Table 1. Table 2 shows composition examples of the base material. An example of the sintered densified material is Cu-10 wt% Sn-0.2 wt% P.

2. 2. Contact chip manufacturing method 2-1. Press Forming-Sintering FIG. 2 is a diagram showing a first manufacturing method (press forming-sintering) according to Embodiment 1 of the present invention.

  First, the hard particle powder is 0.5 to 1% by weight, the Cu-10% by weight Sn-0.2% by weight P powder is 1% by weight, and the remainder is Cu powder (# 51 manufactured by Nikko Metal Co., Ltd.). Weigh and mix as above.

Next, 4 t / cm < ² > compacting is performed with 100 t Amsler. Thereby, a molded body of 10 mm × 12 mm × 80 mm is formed.

  Next, the molded body is vacuum sintered at a temperature of 900 ° C. to 1100 ° C. (preferably 1050 ° C.). By sintering at a temperature higher than the melting point of the sintered densified material and immediately below the melting point of Cu, the sintered densified material can be made into a liquid phase and the sintered density can be increased.

  Next, the vacuum sintered body is rolled by 15%. Thereby, the oxide film can be broken to increase the density.

  Next, vacuum annealing is performed at a temperature of 400 ° C. or higher (preferably 400 ° C.) on the rolled body. The reason why the temperature is set to 400 ° C. is that it is the temperature at which the electrical conductivity is recovered most in the copper-based material, and is equal to or higher than the recrystallization temperature in order to completely remove the processing strain.

  Next, outer diameter processing and inner diameter processing are performed by machining. Thereby, the contact chip 2 is manufactured.

2-2. Extrusion molding-degreasing-sintering (metal injection molding method)
FIG. 3 is a diagram showing a second manufacturing method (metal injection molding method) according to Embodiment 1 of the present invention.

  First, the hard particle powder is 0.5 to 1% by weight, the Cu-10% by weight Sn-0.2% by weight P powder is 1% by weight, and the balance is Cu powder (# 51 made by Nikko Metal Co., Ltd.) Weigh as follows. These metal powders and an amide compound binder are kneaded.

Next, the kneaded mixture is injection molded.
Next, the molded body is degreased by holding the injection-molded molded body at a temperature of 400 ° C. ± 10 ° C. for 40 hours. Next, the compact after degreasing is vacuum sintered at a temperature of 900 ° C. to 1100 ° C. (preferably 1050 ° C.). By sintering at a temperature higher than the melting point of the sintered densified material and immediately below the melting point of Cu, the sintered densified material can be made into a liquid phase and the sintered density can be increased.

  Next, outer diameter processing and inner diameter processing are performed by machining. Thereby, the contact chip 2 is manufactured.

  In the present embodiment, the manufacturing method of the contact chip 2 is 2-1. Press molding-sintering, 2-2. Although the metal injection molding method is described, the present invention is not limited to this, and the contact chip 2 can be manufactured by casting.

3. 3. Welding test and results 3-1. As a test contact tip material, Cu contains 1 wt% Cu-10 wt% Sn-0.2 wt% P as a sintered densification material and 0.5 wt% SiO ₂ as hard particles. material (0.5SiO2), materials obtained by adding Mo ₂ C 1 weight percent hard particles with Cu-10 to wt% Sn-0.2 wt% P and containing 1 wt% as a sintering densification material Cu ( 1Mo2C), a material containing 1% by weight of Cu-10% by weight Sn-0.2% by weight P as a sintered densification material and 1% by weight of TiC as hard particles (1TiC) was used. Using these materials, contact chips were manufactured by the first manufacturing method (press molding-sintering) described above.

Weldability and durability were evaluated when welding length 11 m was continuously welded for 30 minutes with each of the contact tips. Specifically, the following (1) to (3) were evaluated.
(1) It was evaluated whether or not the contact tip was welded to stop feeding the welding wire.
(2) Welding voltage and current stability were evaluated.
(3) The amount of wear at the tip of the contact tip was evaluated by the change in roundness before and after welding.

The roundness was obtained by measuring the tip hole diameter at four points and calculating the difference between the maximum value and the minimum value. The welding conditions are as follows.
・ Bead on plate ・ Power supply Matsushita AEII-500
・ Current 400A ・ Voltage 36V
・ Feed 37cm / min
・ Welding wire diameter φ1.4
・ Protrusion 25mm
・ Use of mixed gas of Ar 80% and CO ₂ 20%

3-2. Results The results for the above evaluation are shown in Table 3. As shown in Table 3, the wear resistance was better than that of the conventional contact tip, and the effect of improving the wear resistance by the hard particles could be confirmed. Further, the feeding of the welding wire did not stop, and the welding wire was not clogged or seized. Further, the contact tip to which 0.5 wt% SiO ₂ was added had higher current and voltage stability than the conventional material, and the amount of spatter scattered during welding was small. In addition, the target property is expected to be good from the result of roundness before and after welding.

  According to the first embodiment, since the heat resistance is improved by dispersing the hard particles, it does not re-dissolve like the conventional precipitation effect type chrome copper. Therefore, even if the welding electrode is used at a temperature exceeding 500 ° C. due to a high current flowing through the welding electrode, it is difficult to soften and can maintain high wear resistance and seizure resistance. Is resistant to thermal shock such as repeated heating. For this reason, the lifetime of the welding electrode can be extended, the replacement frequency of the welding electrode can be reduced, and the facility operation rate can be increased as a whole. Further, the severer the welding conditions, the longer the life can be achieved than chromium copper which is a conventional welding electrode material.

  In addition, in conventional welding electrodes made of chrome copper, iron easily diffuses into the electrode, and the iron content abnormally melts, resulting in a decrease in conductivity and abnormal contact resistance between the welding wire and the welding electrode. Increased welds occur. In contrast, in the welding electrode according to the present embodiment, it is considered that the hard particles can suppress the diffusion of iron, suppress the distortion of the base material, and maintain high strength even at high temperatures.

  In the first embodiment, since the welding electrode is manufactured by powder sintering, the degree of freedom of the shape can be increased, the electrode can be manufactured in a near net shape, and the manufacturing cost can be reduced.

(Embodiment 2)
FIG. 4 (A) is a plan view showing a spot welding electrode which is an example of a welding electrode according to Embodiment 2 of the present invention, and FIG. 4 (B) shows the spot welding electrode shown in FIG. 4 (A). It is a figure which shows a mode that a workpiece | work is welded using.

  While the workpiece 4 as a welding object is crimped by the spot welding electrodes 5 and 6, electricity is passed from the + electrode to the − electrode, and the metal is melted and welded by resistance heat.

  As the material of the spot welding electrodes 5 and 6, the same material as that of the contact tip of the first embodiment is used. Moreover, the manufacturing method of a spot welding electrode uses the manufacturing method similar to Embodiment 1, ie, the 1st manufacturing method (press molding-sintering) and the 2nd manufacturing method (metal injection molding method). it can.

  In the second embodiment, the same effect as in the first embodiment can be obtained.

In addition, this invention is not limited to the said embodiment and said Example, A various change can be implemented within the range which does not deviate from the main point of this invention. For example, in the first and _second embodiments, the welding electrode in which any one hard particle of SiO ₂ hard particles, Mo ₂ C hard particles, and TiC hard particles is dispersed by 0.1 wt% to 2 wt% is used. Although it is used, the present invention is not limited to this, and at least one kind of hard particles out of SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles is dispersed in a total amount of 0.1 wt% to 2 wt%. It is also possible to use a welding electrode.

It is a figure which shows typically a mode that it welds using the contact tip which is an example of the electrode for welding by Embodiment 1 of this invention. It is a figure which shows the 1st manufacturing method (press molding-sintering) by Embodiment 1 of this invention. It is a figure which shows the 2nd manufacturing method (metal injection molding method) by Embodiment 1 of this invention. (A) is a top view which shows the spot welding electrode which is an example of the electrode for welding by Embodiment 2, (B) typically shows a mode that a workpiece | work is welded using the spot welding electrode shown to (A). FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Nozzle 2 ... Contact tip 3 ... Welding wire 4 ... Welding object (workpiece)
5, 6 ... Spot welding electrode

Claims (7)

At least one hard particle of SiO ₂ hard particles, Mo ₂ C hard particles, and TiC hard particles is dispersed in a total amount of 0.1 wt% to 2 wt%, and the balance is formed of an electrode material made of Cu. An electrode for welding.   2. The electrode material according to claim 1, further comprising at least one element selected from the group consisting of Zn, Sn, and P, wherein the upper limit content of Zn is 0.9 wt%, The upper limit content of Sn is 0.14 weight%, The upper limit content of the said P is 0.02 weight%, The electrode for welding characterized by the above-mentioned.   3. The welding electrode according to claim 1, wherein the powder made of the electrode material is molded and sintered.   3. The welding electrode according to claim 1, wherein the kneaded material containing the electrode material is injection-molded and produced by sintering. This is a method for producing a welding electrode in which at least one hard particle out of SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles is dispersed in a total amount of 0.1 wt% to 2 wt%, and the balance is made of Cu. And
Mixing at least one hard particle powder and Cu powder among SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles;
A step of compacting the mixed powder;
Sintering the green compact molded body at a temperature of 900 ° C. to 1100 ° C .;
The manufacturing method of the electrode for welding characterized by comprising. This is a method for producing a welding electrode in which at least one hard particle out of SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles is dispersed in a total amount of 0.1 wt% to 2 wt%, and the balance is made of Cu. And
A step of mixing at least one hard particle powder, Cu powder and binder among SiO ₂ hard particles, Mo ₂ C hard particles and TiC hard particles;
A step of injection molding the kneaded kneaded product;
Sintering the injection molded molded body at a temperature of 900 ° C. to 1100 ° C .;
The manufacturing method of the electrode for welding characterized by comprising.   7. The welding electrode according to claim 5 or 6, wherein the welding electrode contains at least one element selected from the group consisting of Zn, Sn, and P, and in the mixing step, the group consisting of Zn, Sn, and P. A method for producing a welding electrode, further comprising mixing a powder containing at least one element selected from the group consisting of:

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