Four basic parameters of ultrasonic welding
We now know that the main parameters of ultrasonic welding are: contact pressure, ultrasonic welding time, ultrasonic vibration frequency and amplitude.
1. Ultrasonic frequency
The vibration frequency is determined by the natural frequency of the mechanical system. For general equipment, its size is actually constant at all times, unless there are special needs. When selecting the vibration frequency, the nature and thickness of the welding material should be considered. When the thickness of the welding material is reduced, a higher frequency ultrasonic wave should be used. In this case, increase the frequency as a way to reduce the amplitude without changing the sound power. After the amplitude is reduced, the positive and negative alternating stress acting on the weldment will also be reduced, thus reducing the risk of fatigue damage. This risk is very large when welding particularly thin weldments. Increase the height, the vibration energy consumed in the process of transmitting vibration to the welding place will also increase. From this, we know that when welding thicker weldments, we should choose low-frequency ultrasonic vibration.
2. Welding pressure
The contact pressure ensures that the transmission of ultrasonic vibration can be realized, and at the same time, the metal produces the plastic flow required to form the joint. For weldments of different materials and different thicknesses, the minimum contact pressure required to form the joint is not equal. Its size increases with the flow limit, hardness and thickness of the weld metal. The generally reasonable contact pressure value also increases with the increase of the amplitude.
3. Ultrasonic welding time
According to the nature of the material, thickness and some other parameters, the welding time has different values, and generally does not exceed 4 seconds. The change in the welding time related to the nature and thickness of the weld metal is related to the change in the contact pressure. similar.
4. Ultrasonic amplitude
Amplitude is the basic parameter of ultrasonic welding. It determines the removal of the surface film, the size and position of the plastic deformation zone, and the heating, and therefore determines the quality of the resulting joint. For an ultrasonic horn with a certain amplification factor, The magnitude of its amplitude can be determined by changing the output voltage parameters of the generator. When welding, determine the amplitude according to the nature and thickness of the material, one in the range of 5 to 25 microns.
