The working principle and application scenarios of ultrasound.

When the ultrasonic wave acts on the thermoplastic plastic touch surface, it will cause high-frequency vibration of tens of thousands times per second. When this high-frequency vibration reaches a certain amplitude, it will transmit the ultrasonic energy to the welding area through welding. Due to the acoustic resistance at the interface of the two welding is large, a local high temperature will be caused. In addition, due to the poor thermal conductivity of the plastic, it cannot be distributed in time and gathers in the welding area, causing the touch surface of two plastics to melt rapidly, with certain pressure, making it merge into one. 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 materials. The quality of ultrasonic plastic welding depends on three factors: the amplitude of the transducer welding head, the applied pressure and the welding time. The welding time and the welding head pressure can be adjusted, and the amplitude is determined by the transducer and the horn. These three quantities have a suitable value. When the energy exceeds the suitable value, the melting amount of the plastic will be large, and the welding object will be easily deformed. If the energy is small, it is not easy to weld firmly, and the applied pressure cannot be large. This optimum pressure is the product of the edge length of the welded part and the optimum pressure per 1mm of the edge. Nowadays, all kinds of plastic products have penetrated into various fields of people's daily life, and are also widely used in aviation, ships, automobiles, electrical appliances, packaging, toys, electronics, textile and medical industries.

However, the plastic bonding and heat-sealing processes that have been used for many years are quite backward, not only low in efficiency, but also the adhesive has a certain toxicity, causing problems such as environmental pollution and labor protection. This traditional process is no longer suitable for the development needs of the modern plastics industry, so a novel plastic processing technology - ultrasonic plastic welding stands out for its advantages of high efficiency, high quality, beautiful appearance and energy saving. When welding plastic products, the ultrasonic plastic welding machine does not need to add any adhesives, fillers or solvents, nor does it consume a lot of heat sources. It has the advantages of easy operation, fast welding speed, high welding strength and high production efficiency. Therefore, ultrasonic welding technology is more and more widely used.