Seam Welder Working Principle And Basic Characteristics
Seam welders are widely used in the welding of metal, household appliances, boxes and sealed thin-walled containers, automobiles, fuel tanks and other industries, the most suitable for welding low carbon steel, stainless steel and other materials, pots, barrels, boxes, and sealed thin-walled containers welding.
Seam formation process (intermittent) seam welding, each welding point to go through the pre-press, electric heating and cooling crystallization of three stages. However, due to the seam welding roller electrode and the rapid changes in the relative position between the welding, so that the three-phase welding is not as obvious when differentiating. It can be considered: 1) Under the direct compression of the roller electrode, the metal that is being electrified and heated is in the "energized heating phase". 2) about to enter the roller electrode below the adjacent metal, subject to some preheating and roller electrode pressure, Department at the "pre-pressure stage." 3) The neighboring metal just emerging from the roller electrode begins to cool while on the other hand it is under partial pressure of the roller electrode, which is in the "cooling crystallization stage". Therefore, the welding area under the roller electrode and the metal material on both sides adjacent to it will be in different stages at the same time. For any welding spot on the weld, the process under the roller passes the three stages of "pre-pressure-electric heating-cooling crystallization". As the process is carried out under dynamic conditions, the pre-pressure and cooling crystallization stage of the pressure is not sufficient, the quality of the seam welded joints should generally be less than spot welding, cracks, shrinkage and other defects prone.
According to the wheel electrode rotation (weldment movement) and the welding current through (power) of the machine - with the electrical cooperation, can be divided into the following three.
Continuous seam welding
Wheel electrode continuous rotation, weldment constant velocity, continuous welding current, forming a welding point every half weeks. Welding speed up to 10 ~ 20m / min due to the poor quality of the weld surface, the practical application is limited.
Intermittent seam welding
Continuous constant velocity welding, welding current intermittent through, each "on - off" once formed a solder joint. According to the thickness of the plate welding speed up to 0.5 ~ 4.3m / min widely used, the main production of black metal gas, water, oil seal welds.
Step welding seam
The weldment moves intermittently, and the weld current passes as the weldment is at rest, forming a weld every "pass-and-move" and forging pressure can be applied. Joint formation and spot welding are very similar. Welding speed is low, generally only 0.2 ~ 0.6m / min only for the manufacture of high-sealing aluminum alloy and magnesium alloy weld.
Seam welding basic features
1) seam welding and spot welding is the same heat - mechanical (force) joint welding process. In contrast, the role of mechanical (force) in the welding process is not sufficient (except for stepwise seam welding), the faster the welding speed, the more obvious performance.
2) seam welding seam is formed by the overlap of a part of the welding spots, welding shunt more serious than spot welding, which gives high conductivity aluminum and magnesium alloy plate welding difficulties.
3) roller electrode surface prone to sticky damage to the weld surface quality deterioration, so the electrode dressing is a particularly noteworthy issue.
4) As the cross-sectional area of seam weld seam is usually more than 2 times the longitudinal load-carrying area of the base material (the thinner the plate the greater the ratio), the destruction will inevitably occur in the base metal heat-affected zone. Therefore, sew weld structure rarely emphasize the strength of the joint, the main requirements of its good sealing and corrosion resistance.