Spot welding principle refers to the welding method of forming solder joints between the contact surfaces of two lap workpieces by using cylindrical electrodes during welding.In spot welding, the first pressure to make the workpiece close contact, then connect the current, the workpiece contact melting under the action of resistance heat, after cooling to form a welding point.
Spot welding joint type
Spot welding main applications
(1) lapping of sheet stamping parts, such as automobile cab, carriage, harvester fish scale screen, etc.
(2) thin plate and shaped steel structure slimming and skin structure, such as carriage side wall and ceiling, carriage towing plate, combine harvester funnel, etc.
(3) screen and space frame and cross reinforcement, etc.
Spot welding characteristics
(1) The heating time of the connection area is very short during spot welding and the welding speed is fast.
(2) Spot welding only consumes electricity, and does not need filling material, flux, gas, etc.
(3) spot welding quality is mainly guaranteed by spot welder.Simple operation, high degree of mechanization, automation, high productivity.
(4) low labor intensity, good working conditions.
(5) Because the welding is energized in a very short time, need to use large current and pressure, so the process of program control is more complex, welding machine electric capacity is large, the price of equipment is high.
(6) It is difficult to conduct non-destructive inspection of solder joints.
Spot welding operation to clean the surface of the workpiece before welding, the commonly used removal therapy is pickling removal, that is, the first pickling in the heated concentration of 10% sulfuric acid, and then wash in hot water.
The specific welding process is as follows:
(1) Put the workpiece joint into the spot welding machine between the upper electrode and the lower electrode and clamp;
(2) electrify, make the contact table of two workpiece and be heated, partial melting, forming nugget;
(3) maintain the pressure after the power is cut off, so that the nugget cools and solidifies under the action of pressure to form a solder joint;
(4) remove the pressure and remove the workpiece.
2021-07-02 
