The principle of ultrasonic plastic welding is the heating caused by the impact effect of the contact dissociation of the welding surface, or the heating caused by the alternating sinusoidal stress compression imposed on the welding surface. There is no definite conclusion for these two theories. It is also possible that the two heating effects occur simultaneously. In any case, always this kind of heating effect, so that the welding surface fusion and combination, so plastic ultrasonic welding is sometimes called ultrasonic fusion or ultrasonic bonding.

The absorption of ultrasonic energy varies from plastic material to plastic material, not ultrasonic vibration as a whole, but local selective heating, for example, in hard plastic sandwiching good absorption of hard plastic or then agent, can make hard plastic not heat can be welded. When conveying welding, ultrasonic wave is transmitted to the joint surface in plastic, which causes heat and welding. When hard plastic is used, ultrasonic wave is easier to spread.

2>. Characteristics of ultrasonic plastic welding
1. It can be welded to the welding surface by foreign body such as water or oil
2. Compared with other welding techniques, ultrasonic can weld all thermoplastic plastics
3. Welding time is very short
4. Simple and clean operation, no pollution and environmental protection problems
5. Can reach strong and beautiful welding

Structure design of ultrasonic welding line
Ultrasonic welding does not require all vibration heating, but hope to choose the heat in the welding part, ultrasonic welding, ultrasonic in the plastic is transmitted to the joint with Energy guide Angle < Energy Director >, here heat and welding. Ultrasonic energy can be given out by the very rapid transmission of vibration, but the fusion condition of upper cover and lower cover is impossible, because although on the surface of the surface and the friction can borrow the heat generated by the friction vibration rapidly, but not to destroy the molecular structure of end face materials for fusion, can guide is the main reason why some design and welding parameters setting; Without opening the energy guide point to destroy the surface material molecular structure, it is impossible to weld. Therefore, the surface mechanism design of ultrasonic plastic welding affects the difficulty of welding, the appearance of welding department, processing accuracy, welding strength and water, air tightness, etc.

Factors to be considered in the design of energy point and interface of ultrasonic waveguide
1. It must be a reduced contact surface to facilitate the concentrated transmission of ultrasonic energy, so as to achieve the effect of fast welding without damaging the surface.
2. The fixed part of the melt shall have enough support surface so that the other part can vibrate freely to achieve the effect of sound wave conduction and friction heating and fusion.
3 to reserve enough space, so that the flow of molten material stagnation to prevent the overflow of molten material, and damage the beauty of the product.
4. For the welding of water-tight and air-tight components, plastic material must be considered first, and special surface design should be given.
5. The contact surface (pressing surface) between welding HORN and the processed object should have an appropriate plane to avoid damage to the surface.
6. There should be an appropriate pressing surface above the energy guide point, so that Eli HORN can directly press to transmit ultrasonic wave.
7. The joint surface of the two welds should not be designed too close, but should be a loose joint surface, otherwise it will affect the welding effect.