Induction welding of metals, the operating principle of the technology and the basic principles for work

Induction welding of metals Involves a method of heat treating metal in which the workpiece is heated by electromagnetic induction, resulting in compression. High-frequency currents, ranging from tens of Hz to hundreds of kHz, are used for this process; they are most convenient for introducing into metal. In practice, this type of current, supplied by machine or vacuum tube generators, is always used. This type of welding lasts only a few seconds because the heating process is unrelated to the thickness of the material or its thermal conductivity. Energy consumption is more economical because the heat is generated at the surfaces being joined.

This type of welding is often used in the production of steel pipes. Because steel pipes have high inductive resistance, the high-frequency current does not spread around the perimeter, and the pipes are crimped and welded. Induction welding of metals, namely pipes, is performed by placing the parts in the inductor.

When the parts being welded pass through the inductor, eddy currents are induced at the joint, flowing in the opposite direction to the current in the inductor. Along their path, the currents encounter the joint gap and are directed toward it. The current is concentrated primarily in the surface areas being welded, rapidly heating the metal to the required welding temperature.

Equipment for this type of welding has various applications, but their operating principle is based on applying current to the metal to heat it and weld or solder it in the desired location, achieving this quickly and reliably. Termomaccin induction equipment is popular in pipe production. It is designed for annealing and welding ribbed smooth carbon and stainless steel pipes, as well as hot end forming, annealing refrigeration tubing, and annealing hydroformed pipe ends.

Induction welding of metals includes the basic operating scheme:

• the edges of the welds must be cleaned to a shine, although scale is allowed;
• To enhance the heating effect, a ferrite magnetic core is introduced into the tubular blank;
• A current is supplied, possibly up to hundreds of kHz, to strongly heat the metal.

The welded pipe thickness ranges from 0.5 to 15 mm for high-carbon and low-carbon steel. It is also used for stainless and acid-resistant alloys, copper pipes, bronze, brass, and aluminum alloy components. It should be noted that with increasing pipe diameter, the efficiency of external inductors significantly decreases. The use of internal inductors reduces losses within the pipe blank. Induction welding is an excellent replacement for arc and resistance welding in industrial production. It is used in mechanical engineering, building structures, oil production, and the gas industry.

Advantages induction welding of metals:

• the speed of heating the metal, lasts for several seconds;
• increased service life of the inductor;
• the weld seam is clean, there are no scratches;
• highly automated welding method.

The disadvantages are as follows:

• It is difficult to maintain a uniform gap between the inductor and the surface of the part;
• difficulty in concentrating heating in the welding zone itself;
• high power consumption of electrical energy.