Pipe longitudinal seam welding machine

Seam welding is the same as spot welding, which is a joint process of thermo-mechanical (force). It can be said that seam welding is an upgrade and evolution of spot welding. Spot welding is to obtain a certain strength of the weld joint, while seam welding forms a continuous weld. Seam welding machines are widely used in the welding of thin plates of oil drums, cans, radiators, aircraft, and automobile fuel tanks, as well as sealed containers in jet engines, rockets, and missiles.
The spot welding machine adopts the principle of double-sided double-point overcurrent welding. When working, two electrodes press the workpiece to make the two layers of metal from a certain contact resistance under the pressure of the two electrodes, and the welding current flows from one electrode to the other electrode When the two contact resistance points form an instantaneous thermal fusion, and the welding current flows from the other electrode along the two workpieces to this electrode to form a loop without damaging the internal structure of the welded workpiece. The welding machine uses the high-temperature arc generated by the positive and negative poles in an instant short-circuit to melt the solder and the material to be welded on the electrode to achieve the purpose of combining them. To ensure the size of the nugget and the strength of the solder joint, the welding time and the welding current Can complement each other within a certain range. To obtain a certain strength of the solder joints, high current and short time (strong condition, also called hard specification) can be used, or small current and long time (weak condition, also called soft specification).
Seam welding machine refers to a resistance welding machine in which the weldment is assembled into a lap or butt joint and placed between two roller electrodes. The roller electrode presses the weldment and rotates, continuously or intermittently pulses the power to form a continuous weld. It can also be said that the seam welding machine is an evolution of spot welding. Seam welding is widely used in the manufacture of joints that require tightness. Sometimes it is also used to weld ordinary non-sealed sheet metal parts. The thickness of the welded metal material is usually 0.1~2.5mm.

One of the key factors of weld quality is the configuration of the welding power source. There are currently four power supply configurations or welding methods at home and abroad, the comparison is as follows:
(1) CO2 gas protection power supply (melting pole) uses CO2 gas for protection. Advantages: the low price of C02 gas, high production efficiency, high welding current density, deep weldment matrix molten pool, high melting efficiency, fast deposition speed, production efficiency 2 to 4 times higher than manual welding, and anti-rust and anti-crack performance it is good. Disadvantages: When welding with high current, the welding surface is poorly formed and spattered. After welding, the spatter sticking to the workpiece must be manually removed.
(2) MIG gas shielded welding (melting pole) uses argon gas for protection. Advantages: large welding pool depth, stable welding arc, good weld seam formation, and high production efficiency. Disadvantages: Because the shielding gas uses argon to achieve the welding process, the price of argon is relatively high and the MIG welding power source is 3 to 4 times more expensive than the C02/MAG welding power source.
(3) MAG gas shielded welding power source (melting pole). Use argon and CO 2 mixed gas protection, where argon is 80% and CO 2 is 20%. Advantages: large welding pool depth, high deposition efficiency, small welding spatter, stable welding process, and beautiful welding seam can be obtained.
(4) TIG gas protection power supply (non-melting electrode), using argon gas for protection. The welding power source usually used by our company is this one (manual argon tungsten arc welding). Advantages: Since the electrode only heats the workpiece through the current, the workpiece and the welding wire form a molten pool, so there is no spatter, and the weld is beautifully formed; Disadvantages: the depth of the arc molten pool is shallow, the deposition rate is low, and the production efficiency is not high. Since the welding process uses argon gas for protection, the price is high.

The principle of a seam welding machine is essentially the same as that of spot welding or projection welding. The seam of seam welding is formed by overlapping solder joints. If compared with spot welding or projection welding, it has the following Strengths and weaknesses point:
Advantages: Air-tight or liquid-tight welded joints can be obtained. The welding width of seam welding is narrower than the diameter of spot welding or projection welding, so the overlap width (or margin) of seam welding is smaller.
Disadvantages: Due to the small spot pitch, the shunt of the welding current is larger than that of spot welding. If stepping seam welding is not used, the pressure of each welding spot changes during welding, which is caused by the continuous rolling of the roller electrode. Generally, welding must be performed on a straight line or curved surface. There should be no obstacles along the path of the roller electrode on the weldment, otherwise, special measures such as changing the design of the roller electrode are needed to realize welding. The length of the joint welded by the longitudinal seam welder is limited by the length of the electrode arm (called the depth).

1.Use a grinder to clean the burrs and sundries on both sides of the groove to be welded, and strictly check and control the dimensional tolerance of the groove. Usually, the gap of the seam should be controlled within 10% of the plate thickness.
2.Use acetone or other solvents with a strong degreasing ability to clean the oil and impurities within 15-20mm on both sides of the groove. To avoid welding defects such as pores and slag inclusions.
3.Ensure assembly accuracy to ensure product welding quality.
A. The longitudinal seam welding of the cylinder. A crane can be used to hoist the rounded barrel to be welded to the designated position. The weld is centered by the mechanical centering device.
B. Adjust the weld gap. When the length of the weld is short, not more than 0.5m, the weldment can be tightly fitted from beginning to end during assembly. If the welding seam is long, to prevent the welding seam from shrinking and squeezing each other and causing misalignment and deformation, a gap should be reserved when the weldment is assembled. For example, for a SUS304 stainless steel plate with a length of 1.5 m and a thickness of 8 mm, after many experiments, it is found that the empirical value of the reserved gap is 4 mm, which is more appropriate, and a relatively high-quality weld can be welded.
C. Add arc ignition board. Since arc ignition and arc extinguishing are prone to large splashes and various welding defects, arc ignition plates and lead plates are installed at both ends of the joint. So that the penetrating holes are first produced on the arc pilot plate, and finally the keyholes on the lead plate.
D. Longitudinal seam welding machine for fixing weldments. The pneumatic key-pressing mechanism tightly presses the edge of the workpiece to be welded on the copper backing plate of the supporting shaft, which can effectively prevent the deformation of the weldment during the welding process and ensure the stability of the welding process.
When the diameter of the cylinder is small, process welding is used to weld the outer longitudinal seam of the cylinder. When the diameter of the cylinder is large, the welding of the longitudinal seam of the cylinder is performed from the inner side.

We can provide saw, tig, mig, mag, and other welding methods according to your workpiece thickness and material.