Application of Welding Machines in Transformer Production

In transformer production, the selection of welding machines is highly correlated with the material, thickness and process requirements of the welding parts:

1. Conductive parts (windings, lead wires) → TIG welding machines are preferred to ensure electrical conductivity.
2. Lap welding of thin steel structural parts (iron cores, small accessories) → Resistance welding (spot/seam welding) is preferred for high efficiency and low loss.
3. Long straight welds of thick plates (main welds of oil-immersed transformer tanks) → Submerged arc welding is preferred for high efficiency and high quality.
4. Special-shaped structure/all-position welding (tank corners, enclosures, supports) → Gas metal arc welding is preferred for flexible adaptability.
5. Oil-immersed transformers have much higher requirements for the type and power of welding machines than dry-type transformers, with the core difference lying in the submerged arc welding and high-power gas metal arc welding adopted for tank welding.

The corrugated tank of an oil-immersed transformer (a steel plate welded structure) is the part involving the largest welding workload in production. The metal enclosures and protective frames of dry-type transformers also require welding, which is the main application scenario for submerged arc welding and gas metal arc welding.

Differences Between Submerged Arc Welding, Gas Metal Arc Welding and Resistance Welding

1. Submerged Arc Welding

It belongs to arc welding. It uses the electric arc generated between the welding wire and the workpiece as the heat source to melt the metal. The welding area is completely covered by granular welding flux (buried under the flux layer), and the electric arc burns inside the flux layer. The molten welding flux forms slag and gas to isolate the air and protect the molten pool.

2. Gas Metal Arc Welding (GMAW)

It also falls into the category of arc welding, using an electric arc as the heat source. Its core feature is that a continuously delivered shielding gas (single/mixed gas) is ejected from the welding torch nozzle to form a gas shielding layer around the molten pool for air isolation. The welding wire used is a continuously fed solid or flux-cored welding wire. Gas metal arc welding is further divided into CO₂ gas shielded welding, mixed gas shielded welding (Ar+CO₂/Ar+O₂) and argon gas shielded welding (MIG/MAG). It is currently the most versatile welding process in the industry.

3. Resistance Welding

It is a type of pressure welding without electric arc or welding wire involved. It uses the resistance heat at the contact of workpieces as the heat source. When a large current passes through the contact interface of two workpieces, the resistance heat generated melts the metal at the contact area, and a certain pressure is applied at the same time to fuse the molten metal and form a weld.