Ultrasonic metal welding machine was invented occasionally in 1930's. In the current spot welding electrode plus ultrasonic vibration experiment, the invention of under current can also be welded, which is to grow the ultrasonic metal cold welding skills. Although ultrasonic welding was invented earlier, up to now, its influence mechanism is not very clear. It is similar to friction welding, but there is a difference. Ultrasonic welding has a short time, and the temperature is lower than recrystallization; it is also different from pressure welding, because the static pressure applied is much smaller than pressure welding.
It is generally believed that in the initial stage of ultrasonic welding process, the tangential vibration enters the oxide outside the metal, and the convex part outside the rough and clumsy surface produces repeated micro welding and damage process, which increases the contact area, reduces the temperature of the welding area, and produces plastic deformation at the interface of the weldment. In this way, under the influence of pressure, the solder joints are formed when they are close to the interval where the atomic gravity can produce the influence. The welding time is too long, or the ultrasonic amplitude is too large, which makes the welding strength reduce, even damage.