Introduction to the principle of ultrasonic metal and plastic welding
The main components of the ultrasonic welding system include:
Ultrasonic generator/transducer/horn/welding head triple group/mold and frame.
1. The principle of ultrasonic welding
Ultrasonic welding uses high-frequency vibration waves to be transmitted to the surfaces of two objects to be welded. Under pressure, the surfaces of the two objects are rubbed against each other to form a fusion between molecular layers.
2. The principle of ultrasonic metal welding
The principle of ultrasonic metal welding is a special method of connecting the same or dissimilar metals by using the mechanical vibration energy of the ultrasonic frequency (over 16KHz). When metal is ultrasonically welded, it neither delivers current to the workpiece nor applies a high-temperature heat source to the workpiece, but under static pressure, the vibration energy of the frame is converted into friction work, deformation energy and limited temperature rise between the workpieces. The metallurgical bonding between the joints is a solid state welding that is realized without the base material being melted. Therefore, it effectively overcomes the spatter and oxidation caused by resistance welding. Ultrasonic metal welding machine can perform single-point welding, multi-point welding and short strip welding on thin wire or sheet materials of non-ferrous metals such as copper, silver, aluminum, and nickel. It can be widely used in the welding of SCR leads, fuse pieces, electrical leads, lithium battery pole pieces, and tabs.
3. The principle of ultrasonic plastic welding
When ultrasonic waves act on the thermoplastic plastic contact surface, it will produce tens of thousands of high-frequency vibrations per second. This kind of high-frequency vibration with a certain amplitude will transmit the ultrasonic energy to the welding area through the upper weldment. Because the welding area is two The acoustic resistance at the welding interface is large, so local high temperature will be generated. In addition, due to the poor thermal conductivity of the plastic, it cannot be distributed in time for a while, and it gathers in the welding area, causing the contact surface of the two plastics to melt rapidly, and after a certain pressure is applied, they are merged into one. After the ultrasonic stops, let the pressure continue for a few seconds to make it solidify and shape, so that a strong molecular chain is formed to achieve the purpose of welding, and the welding strength can be close to the strength of the raw material.
The quality of ultrasonic plastic welding depends on three factors: the amplitude of the transducer's welding head, the applied pressure and the welding time. The welding time and welding head pressure can be adjusted, and the amplitude is determined by the transducer and the horn. There is a suitable value for the interaction of these three quantities. When the energy exceeds the suitable value, the melting amount of the plastic is large, and the welded material is easy to deform; if the energy is small, it is not easy to weld firmly, and the applied pressure cannot be too large.