To understand lithium battery spot welding machine, then we have to start from its source resistance welding technology.
Definition of resistance welding principle: the method of welding by applying pressure through the electrode after the weldment is combined, and the resistance heat generated by the current passing through the contact surface of the joint and the adjacent area is also known as contact welding. When working, the two electrodes squeeze the workpiece, so that the two layers of metal (metal and battery positive and negative electrodes) form a certain contact resistance under the pressure of the two electrodes. When the welding current flows from one electrode to the other, instantaneous thermal welding is formed at the two contact resistance points, and the welding current flows instantaneously along the two workpieces from the other electrode, forming a loop without destroying the internal structure of the workpiece to be welded.
Main features of resistance welding:
(1) The welding voltage is very low (1~12V), the welding current is very large (tens ~ thousands of amps, amperes), and the welding time to complete a joint is extremely short (0.01~a few seconds), so the productivity is high.
(2) When heating, mechanical pressure is applied to the joint, and the joint is welded under the action of pressure, so there is no need to fill the metal during welding.
Resistance welding is divided into spot welding, seam welding, convex welding and butt welding according to different process methods.
The lithium battery spot welding machine is also a kind of resistance welding.
Spot welding is a resistance welding method in which weldments assemble joints and press between two electrodes, and use resistance to heat melt the base metal to form a solder joint. Spot welding is mostly used for the connection of thin plates.
Process of spot welding:
(1) Pre-pressurization to ensure good contact of the workpiece.
(2) Turn on electricity to form a molten core and a plastic ring at the weld.
(3) Power off forging and pressing, so that the molten core cools and crystallizes under the pressure to form a solder joint with dense structure, no shrinkage holes and cracks.
Spot welding process parameters such as welding current, electrode pressure, power-on time and electrode working surface size have a significant impact on welding quality.
