On the composition of electrode materials used in spot welding machine and touch welding machine

1. What is the difference between CuCr and CuCrZr?

Common points: they are all copper alloy materials, suitable for resistance welding electrode, with high hardness and strength; it has the characteristics of high temperature softening, and can resist high temperature while maintaining its chemical and physical properties; the temperature is about 450 ℃ ~ 550 ℃; it has certain wear resistance and long service life; it has good electrical conductivity.

Difference: in copper alloy smelting, CuCr only adds Cr element to copper; CuCrZr, in addition to adding certain Cr element, also adds Zr element, and Zr element has the characteristics of wear resistance and toughness. Therefore, compared with CuCr, CuCrZr has better wear resistance, longer service life and higher high temperature softening temperature. Therefore, CuCrZr is used as electrode material Material has more advantages.

2. Why do electrodes stick when welding galvanized sheet?

This is because the electrode material used is CuCr or CuCrZr. When the Cu in the material is melted at high temperature during welding, the zinc (Zn) and Cu of the galvanized sheet will react to form the alloy of Cu and Zn, and CuZn is exactly the composition of brass alloy. Therefore, chemical reaction occurs, which leads to the loss of electrode material and adhesion.

3. How to solve the problem of bonding when welding galvanized sheet?

a) The best solution is to use dispersion strengthened copper (cual2o3). Cual2o3 is an excellent electrode material for resistance welding. Its softening temperature is up to 900 ° and it has good electrical conductivity and wear resistance, long service life and no adhesion between electrode and workpiece.

b) If CuCr or CuCrZr are to be used, the two-stage current welding method can be used. The spot welding machine must have two sections of current output. The first current (smaller) will break down the coating first, and the second current will weld the workpiece. In this way, the workpiece will be firmly welded, and the phenomenon of electrode sticking will be improved.

4. What is KCF and why should it be used for welding nuts and bolts?

KCF is a kind of special ferrochromium alloy. It has good hardness, strength and toughness. After special heat treatment, it has the characteristics of low-voltage insulation on the surface. When welding nuts or bolts, insulation protection is required for the thread part to prevent the thread from being burned due to shunt flow. As KCF is used as the bar forming material, the processing is more convenient and the cycle will be shorter. Therefore, KCF is used The material is ideal as the positioning core.

Of course, ceramic materials can also be used as positioning cores. The hardness of ceramics is completely no problem. However, because it is easy to be broken and broken, it is not ideal, and the molding needs a mold. Therefore, it is more difficult to process the special positioning core, and the production cycle is longer, and the side cost of small batch is very high. If the batch is large and standardized, the cost will be lower.

5. Introduction to electrode materials:

Chromium zirconium copper (CuCrZr)

Chromium zirconium copper (CuCrZr) is the most commonly used electrode material for resistance welding, which is determined by its excellent chemical and physical properties and good cost performance.

1) Chromium zirconium copper electrode, it achieves a good balance of four performance indexes of welding electrode

Excellent electrical conductivity --- ensure the minimum impedance of welding circuit and obtain excellent welding quality?

High temperature mechanical properties --- high softening temperature guarantees the performance and life of electrode materials in high temperature environment?

Wear resistance: the electrode is not easy to wear, prolong the service life and reduce the cost?

High hardness and strength - ensure the electrode head work under a certain pressure, not easy to deform and crush, ensure the welding quality

explain:

1) The chemical composition of the alloy was analyzed according to zbh62-003.1-h62003.8;

2) The hardness of the alloy is measured according to gb230, and the average value of three points is measured for each sample;

3) Eddy current conductivity meter (eddy current comparison method) is used for conductivity measurement. Three points shall be measured for each sample, and the average value shall be taken. The sample with diameter less than 15mm can be measured according to gb3048.2;

4) For the softening temperature test, put the sample in the furnace heated to 550 ℃ (after closing the furnace door, it is required to return to this temperature within 15 min after closing the furnace door, keep the temperature for 2 h, then quench water to cool down, and measure the temperature value of the sample chamber (take the average value of three points)) and its hardness shall not be reduced by more than 15% compared with the original hardness value.

2) Electrode is a kind of consumable in industrial production, and its consumption is relatively large, so its price and cost is also an important factor to be considered. Compared with its excellent performance, chromium zirconium copper electrode is cheaper and can meet the needs of production.

3) Chromium zirconium copper electrode is suitable for spot welding and projection welding of carbon steel plate, stainless steel plate, coated plate and other parts. Chromium zirconium copper material is suitable for manufacturing electrode parts such as electrode cap, electrode connecting rod, electrode head, electrode holding rod, projection welding special electrode, roll welding roller, conductive nozzle and other electrode parts.

Beryllium copper (BeCu)

Beryllium copper (BeCu) electrode material has higher hardness (up to hrb95 ~ 104), strength (up to 800MPa / N / mm2) and softening temperature (up to 650 ℃) compared with Cr Zr Cu electrode material, but its conductivity is much lower and worse. Beryllium copper (BeCu) electrode material is suitable for welding plate parts with high pressure, as well as hard materials, such as roll welding roller for welding seam; it is also used for some electrode accessories with high strength requirements, such as crank electrode, connecting rod, robot converter; at the same time, it has good elasticity and thermal conductivity, which is very suitable for manufacturing stud welding chuck. Beryllium copper (BeCu) electrode is a kind of special electrode material because of its high cost

Copper alumina (cual2o3)

Copper alumina (cual2o3) is also called dispersion strengthened copper. Compared with chromium zirconium copper, it has higher strength (up to 600MPa / N / mm2), excellent high temperature mechanical properties (softening temperature up to 900 ℃) and good electrical conductivity (conductivity 80 ~ 85 IACS%), with excellent wear resistance and long service life. Copper aluminum oxide (cual2o3) is a kind of electrode material with excellent performance, no matter its strength, softening temperature or conductivity are very superior. Especially, it is used to weld galvanized sheet. It will not stick to the workpiece like Cr Zr Cu electrode. It can effectively solve the problem of welding galvanized sheet, improve the efficiency and reduce the production cost. Aluminum oxide copper electrode has excellent welding performance, but its current cost is very expensive, so it can not be widely used at present. However, the excellent welding performance of galvanized sheet and the widespread use of galvanized sheet make its market prospect broad. Aluminum oxide copper electrode is suitable for welding galvanized steel plate, aluminum products, carbon steel plate, stainless steel plate and other parts

Tungsten (W), molybdenum (MO)

Tungsten electrode materials include pure tungsten, tungsten based high specific gravity alloy and tungsten copper alloy. Tungsten based high density alloy is sintered by adding a small amount of nickel iron or nickel copper into tungsten. Tungsten copper composite material contains 10-40% copper by weight

Molybdenum electrode (molybdenum) tungsten and molybdenum electrode has the characteristics of high hardness, high melting point and excellent high-temperature working performance. It is suitable for welding non-ferrous metals such as copper braided belt of switch and metal sheet.

Appendix: chemical and physical properties of electrode materials

1) The forming process of CuCrZr is as follows

Vacuum melting → hot forging (extrusion) → solid melting → cold forging (drawing) → aging treatment

The above process and strict quality control ensure excellent conductivity, high strength and good wear resistance.

The standard electrode head, electrode cap and special-shaped electrode are manufactured by cold extrusion process and precision machining, which further improves the density of products, makes the product performance more excellent and durable, and ensures the stability of welding quality.

The size of round bar is 3.0 ~ 45mm. The square or disc is usually forged and customized according to the customer's requirements.

Chemical composition and physical properties of Al 2O 3 Cu and BeCu