The seam welder is widely used in industries such as hardware, household appliances, barrels, boxes, and sealed thin-walled containers for welding, as well as the automotive and fuel tank industries. It is most suitable for welding pots, barrels, boxes, and sealed thin-walled containers made of low carbon steel, stainless steel and other materials.
Working principle of seam welder
The process of forming a seam weld joint (intermittent) requires each welding point to go through three stages: pre-pressure, electric heating, and cooling and crystallization. However, due to the rapid change in the relative position of the roller electrode and the workpiece during seam welding, these three stages are not as distinct as in spot welding.
It can be considered that:
The metal directly pressed by the roller electrode and being electrically heated is in the "electric heating stage".
The adjacent metal below the roller electrode, which is about to enter, undergoes certain preheating and partial pressure from the roller electrode, and is in the "pre-pressing stage".
The adjacent metal that has just come out from below the roller electrode begins to cool on the one hand, and is still subject to partial pressure from the roller electrode, and is in the "cooling and crystallization stage".
Therefore, the welding area under the roller electrode and the two adjacent metal materials will be in different stages at the same time. For any welding point on the weld seam, the process of passing through the roller is to experience the "pre-pressure-electric heating-cooling and crystallization" three stages.
Since this process is carried out under dynamic conditions, the pressure during the pre-pressure and cooling crystallization stages is not sufficient. As a result, the quality of seam weld joints is generally poorer than that of spot welding, and defects such as cracks and shrinkage holes are more likely to occur.
Working method of seam welder
According to the mechanical-electrical coordination mode of roller electrode rotation (workpiece movement) and welding current passing (electrical connection), there are three types:
Continuous seam welding
The roller electrode rotates continuously, the workpiece moves at a uniform speed, and the welding current passes continuously, forming a welding point every half cycle. The welding speed can reach 10-20m/min, but due to poor surface quality of the weld seam, its practical application is limited.
Intermittent seam welding
The workpiece moves continuously at a constant speed, and the welding current passes intermittently, forming a welding point every time it is connected or disconnected. The welding speed can reach 0.5-4.3m/min according to the plate thickness. It is widely used in the manufacture of gas, water, and oil-sealed weld seams of black metal.
Stepping seam welding
The workpiece moves intermittently, and the welding current passes when the workpiece is stationary, forming a welding point every time it is connected or moved, and can apply forging pressure. The joint formation process is similar to spot welding. The welding speed is relatively low, generally only 0.2-0.6m/min, and is only used for the production of high-sealed weld seams of aluminum and magnesium alloys.