(1) Vibration and friction stage: The first process of ultrasonic metal welding is mainly a friction process, and its relative friction speed is similar to that of friction welding, but the amplitude is only tens of microns. The main function of this process is to remove impurities such as oil and oxides on the surface of the weldment and expose the pure metal surface. During welding, due to the ultrasonic vibration of the upper sonotrode, friction between the upper sonotrode and the upper weldment causes a temporary connection, and then the ultrasonic vibration energy is directly transmitted to the contact surface between the weldments through them, which produces violent Relative friction, from the initial friction between individual bumps, gradually expands to surface friction, while destroying, squeezing and dispersing the oxide film and other attachments on the surface.
(2) Temperature rise stage: In the continued ultrasonic reciprocating friction process, the temperature of the contact surface rises (the temperature of the welding zone is about 35% to 50% of the melting point of the metal), the deformation resistance drops, and the static pressure and elastic mechanical vibration Under the combined action of the alternating joint stress caused, the plastic flow of the contact surface between the weldments continues, so that the broken oxide film continues to be dispersed and even penetrates into the welded material, and the atoms on the pure metal surface are infinitely close to atomic energy. Within the scope of gravity, atoms diffuse and combine with each other to form common crystal grains or recrystallize.
(3) Solid phase bonding stage: With the progress of the friction process, the microscopic contact area becomes larger and larger, and the plastic deformation of the contact part is also increasing. The eddy current plastic flow layer is even formed in the welding area, and the mechanical interaction between the weldments occurs. Bite. In the initial stage of welding, there are fewer occlusal points and smaller occlusal area, and the joint strength is not high. It is quickly destroyed by the shear stress caused by ultrasonic vibration. As the welding process progresses, the number of occluding points and the occluding area gradually increase. When the bonding force between the weldments exceeds the bonding force between the upper sonotrode and the upper weldment, the tangential vibration cannot cut off the bond between the weldments. Form firm
Contact Person: Ms. Hogo Lv