While improving the conductivity, it can effectively prevent the “bite” phenomenon of the bearing bush. It is widely used in the welding of hardware, home appliance barrels, boxes and sealed thin-walled containers, automobiles, fuel tanks and other industries. It is most suitable for welding low-carbon steel, stainless steel and other materials. Welding of pots, barrels, boxes, and sealed thin-walled containers.
The weldment of the seam welder is assembled into a lap or butt joint and placed between two roller electrodes. The roller electrode presses the weldment and rotates, and continuously or intermittently transmits electricity to form a continuous weld. Resistance welding method. It can also be said that seam welding is an evolution of spot welding. Another form of spot welding by spot welding machine, during seam welding, the individual welding spots that form a continuous seam overlap each other without any division. Due to the close distribution of adjacent welding points, although the thermal metal resistivity adjacent to the welding point is high, the current shunting is still very large. stability.
Upset forging can also discharge oxides out of the weld with the liquid metal. There are fewer defects such as inclusions and incomplete penetration in the weld. The flashing process has a strong self-adjusting function, and the requirements for strict compliance with specifications are low, and the welding quality is low. Stable. Electric power per unit of welding cross-sectional area is small, and low-carbon steel only needs (0.1-0.3) KVA/mm2 electric power. Electroslag welding can only be used for vertical welding of steel bars, and cannot be used for welding in other directions. The highest pass rate is air pressure welding, which can fully achieve a 100% pass rate; among several welding methods, the threaded connection method has the highest cost, which is about 20 times the cost of air pressure welding. If the electricity consumption is calculated, the air pressure welding method has the lowest cost of about 0.3 yuan/head. If the electricity consumption is not calculated, the flash welding method has the lowest cost. From the point of view of equipment investment: the lowest input cost is the threaded connection. Some threaded casing equipment manufacturers rent out steel bar buckle machines for free due to the high cost of threaded casing joints.
Secondly, the investment cost of air pressure welding is small. Because both flash welding and electroslag welding need to be equipped with a large electric welding machine, the investment cost is the largest in the order of flash welding and electroslag welding. The principle of seam welder is a kind of resistance welding. That is to say, two conical roller electrodes are used to press the metal cover plate to be encapsulated and the metal frame on the tube shell, and the welding current is divided into two currents from one end of the transformer secondary coil through one of the conical roller electrodes, one is The current flows through the cover plate, and another current flows through the shell, through another conical electrode, and returns to the other end of the transformer secondary coil. The high resistance of the whole circuit is at the contact between the electrode and the cover plate, due to the pulse current Generates a lot of heat.