Through the friction between the molecules of the object, the vibration energy generated by the ultrasonic wave is converted into heat energy, so that the welding surfaces of the object parts are fused together. This is the principle of the ultrasonic welding machine. Ultrasonic welding machine uses the vibration frequency of ultrasonic waves to weld objects. There are many kinds of equipment for welding objects through ultrasonic waves, including pneumatic transmission systems, transducers and ultrasonic generators, control circuits and welding heads. The working process of the ultrasonic welding machine: first, the ultrasonic generator converts the high-voltage current into high-frequency electric energy, and then the converted high-frequency electric energy is converted into mechanical vibration of the same frequency through the transducer, and then the mechanical vibration passes through the action of the horn. It is amplified and transmitted to the welding head, and finally the welding head transfers the received vibration energy to the joint surface between the welding objects.
From the parameters of each ultrasonic welding machine, most of the ultrasonic welding frequencies are around 15KHz-40KHz, and the main parameters of the ultrasonic welding machine are the pressure generated during welding, the amplitude, the time generated during welding, and the welding time. power and ultrasonic frequency.
1. The welding power and ultrasonic frequency of the ultrasonic welding machine
In the process of welding objects with ultrasonic waves, the generated ultrasonic frequency does not directly affect the quality of the welded objects, but if the frequency generated during ultrasonic welding is not in harmony with the fundamental frequency generated by the horn of the ultrasonic welding machine, it will It emits noise that hurts people's ears, and the large ultrasonic clutter is not conducive to the fixation of the welding workpiece, and even makes the welding workpiece fly out and cause accidents. At the same time, the selection of the ultrasonic welding frequency should take into account the resonance frequency of the entire system to avoid the phenomenon of resonance.
2. Amplitude of ultrasonic welding
The amplitude of the process parameters of the ultrasonic welding machine needs to be determined at the first time, and the output power of the ultrasonic welding machine has a direct relationship with the amplitude generated during welding. Different amplitudes should also be selected for different welding materials. The amplitude of the amplitude is not only related to the hardness of the welding material, but also to the yield strength of the material; for the different materials of the welding object, the amplitude of the selected amplitude is usually 15μm. -60μm or less. At the same time, the magnitude of the amplitude is also related to the frequency of the welding equipment, the welding form and other factors.
3. The pressure generated by ultrasonic welding and the time used
In the process of using ultrasonic to weld objects, the pressure during welding has a direct impact on the strength of the welded joint. Only when the welding pressure is sufficient can the fusion of the welding workpiece be ensured, thereby improving the firmness of the welding. However, if the welding pressure is too high, the workpiece material of the molten layer will be seriously extruded, so that the thickness of the molten layer will be reduced and the welding will be weak. The time used for welding will directly determine the amount of heat generated by the welding interface. If the time used for welding is not enough, the welding material will not be melted in place and the fusion will not be tight, resulting in weak welding; but if welding If the time is too long, the material will be melted excessively, and the material other than the welding line will be melted, resulting in the failure of the welding work. Therefore, the time spent in welding will directly affect the firmness of the welded joint.