Projection welding - a kind of spot welding, in which the parts are connected in some areas with a pre-prepared or natural projections (reliefs) by application of compression force and the supply current.
The essence of the process
On the surface, one or both of the welded blanks advance vyshtampovyvayutsya protrusions (relief), round, circular, oblong or other shapes. Then the parts are clamped between the electrodes, usually shaped plate, with application to him force F St. , and turn the welding current.
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| Projection welding process |
Metal protrusion begins to heat rapidly and progressively deformed. At a certain stage in the contact zone is formed by melting the workpieces as in spot welding. As the flow of welding current increases the volume of zone melting, and the metal ledge, deformed, out on the outer surface of the workpiece. After switching off the current melt is cooled and crystallized to form a nucleus surrounded by a sealing belt plastically deformed metal, in which connection is formed without melting.
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| formation of compounds with projection welding |
The main difference from the projection welding point is that the contact between the workpiece and weld shape and size are determined by projection rather than the form of the working electrode surface, as in the conventional spot welding. Thus, the pre-prepared projections for a course of projection welding machines can produce up to several tens of spot welds.
The electrodes have a long service life due to the large contact surface and the concentration of power and pressure in the reliefs of the workpiece.
The disadvantage of this technology is the increased electrical power required for welding presses.
Welding technology:
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