凸焊是点焊的变种，其焊接过程与原理和点焊相同. 因此，所用的凸焊机与点焊机基本相同 。区别在于：
The projection welders are vertical motion type pressurizing mechanisms. Due to the compressibility of the air, the follow-up of the pneumatic welder is superior to that of the hydraulic welder, and the pneumatic system can be used for the vertical motion welder of all powers, so the projection welder mostly uses a pneumatic system. The projection welder has good rigidity, but the extension length of the electrode arm is generally smaller than that of the spot welder.
Projection welding is a variant of spot welding, and the welding process is the same as the principle and spot welding. Therefore, the projection welder used is basically the same as the spot welder. The difference is that:
1. The upper and lower electrodes are not round rods but flat plates, and the working surface is flat. Usually, standard T-shaped grooves are provided for mounting bolts;
2, the welding machine power and electrode pressure is large, determined by the number of bumps or the area of the convex ring.
3. Generally, the electrode pressurization is only suitable for the direct press type, that is, the upper electrode is moved vertically to its working surface.
The projection welding machine is general-purpose and special-purpose. if the spot welding attachment is added to the upper and lower electrodes of the universal welding machine, it becomes a projection welding and spot welding machine.