(1) Amplitude: Amplitude is a key parameter for materials that need to be welded [9]. Different transducers have different output amplitudes. The same transducer can also be equipped with different horns and welding heads. Change the working amplitude of the welding head to meet the welding requirements of different materials. The output amplitude of the usual transducer is 5-20 sm, and the working amplitude is generally about 10-30 sm. The working amplitude is the same as the output amplitude of the transducer, the shape of the horn and the welding head, the front-to-rear area ratio and other factors. related.
(2) Frequency: Any ultrasonic welding machine has a center frequency, such as 20, 40kHz, etc. The working frequency of the welding machine is mainly composed of ultrasonic transducer (Transducer), ultrasonic horn (Booster), and welding head (Horn ) Is determined by the mechanical resonance frequency. The frequency of the ultrasonic generator is adjusted according to the mechanical resonance frequency to achieve consistency, so that the welding head works in a resonant state, and each part is designed as an integral multiple of a half-wavelength resonator. Both the ultrasonic generator and the mechanical resonance frequency have a resonance working range. Taking 20kHz as an example, the resonance working range is generally set to (20 to 0.3)kHz, and the welding machine can basically work normally within this range. When making each welding head, the resonant frequency will be adjusted, and the error between the resonant frequency and the design frequency is required to be less than 0.1kHz. At present, the frequency used in ultrasonic metal welding is usually 20kHz. In fact, the frequency of the welding head is generally controlled at 19.90~20.10kHz, with an error of less than 5‰.
(3) Node: The welding head and the ultrasonic horn are designed as a half-wavelength resonator of the working frequency. In the working state, the amplitude of the two end faces is the largest and the stress is the smallest, and the node amplitude corresponding to the middle position is Zero, the maximum stress. The node position is generally designed as a fixed position, but the thickness of the usual fixed position design is greater than 3mm, or the groove is fixed, so the fixed position is not necessarily zero amplitude, which will cause some calls and a part of energy loss. For calls, rubber rings are usually used to isolate them from other components, or to use vibration-reducing structure design for shielding. Energy loss should be fully considered when designing amplitude parameters. The rubber ring is called soft fixation, and the vibration reduction structure design is generally called hard fixation. In ultrasonic metal welding, a hard fixed structure is usually used, and the hard fixed structure also has an end surface fixed mode.
(4) Texture: Ultrasonic metal welding is usually on the surface of the welding position, and the surface of the base is designed with a mesh. The purpose of the mesh design is to prevent the sliding of metal parts and transfer energy to the welding position as much as possible. The mesh design generally has square, diamond, and strip mesh. The size and depth of the mesh are determined according to the specific welding material requirements.
(5) Power supply: There is no big difference between the ultrasonic power supply used for metal welding equipment and the ultrasonic power supply used for plastic welding equipment. The particularity is that the welding metal has higher requirements. In order to meet the needs of metal welding, it is necessary to use an intelligent ultrasonic power source-ultrasonic generator. The ultrasonic generator has an automatic frequency tracking system. During the welding process, changes in load and temperature rise will cause the resonance frequency of the vibration system to change. Therefore, the ultrasonic generator is required to track the frequency of the vibration system, so that the generator and the vibration system Always in a resonance state, the frequency automatic tracking system can compensate for the changes in the working state during the welding process, so that the system is in resonance again and the welding parameters are stabilized. The focus is on the stability of the amplitude, which is of great significance for metal welding.
(6) Transducer: There is no big difference between the transducer used for metal ultrasonic welding equipment and the transducer used for plastic ultrasonic welding equipment. The special feature is that the welding metal materials have higher quality requirements, because When welding metal materials, large instantaneous power is often required, and the transducer is required to have high power capacity and low impedance. Therefore, low-power transducers used for plastic ultrasonic welding devices cannot be used for ultrasonic welding of metals.
