الوصف

Description:
 
Ultrasonic welding is a local rapid heating and cooling process. The welding zone cannot be freely expanded and contracted due to the restraint of the surrounding workpiece body. After cooling, welding stress and deformation occur in the weldment. Important products need to eliminate welding stress after welding and correct welding deformation. Modern welding techniques have been able to weld welds with no internal or external defects and mechanical properties equal to or even higher than the welded joints. The mutual position of the welded body in space is called the welded joint, and the strength of the joint is affected by the quality of the weld, and also related to its geometry, size, stress and working conditions. The basic form of the joint has docking, lap joint, T-joint (orthogonal joint) and corner joints.
Ultrasonic plastic welding machine requirements for welding workpiece materials: Ultrasonic plastic welding machine has requirements for the material to be welded. Not all materials can be welded. Some people think that any material can be welded. This understanding is wrong. Different materials can be welded directly, some are basic phase fusion, and some are not phase fusion. The melting point between the same material is the same, and the principle is that it can be welded, but when the melting point of the workpiece to be welded is greater than **0 ° C, it is not suitable for ultrasonic welding. Because the ultrasonic is instantaneously melting the workpiece molecules, the judgment is based on within 3 seconds, and the welding cannot be performed well.
The selection of the output power of the ultrasonic plastic welding machine: the size of the ultrasonic output power is determined by the diameter and thickness of the piezoelectric ceramic piece, the material and the design process. Once the transducer is shaped, the maximum power is also fixed. Measuring the amount of output energy is a complicated process. The larger the transducer, the more power the circuit uses and the higher the output energy. It requires a fairly complex amplitude meter to accurately measure its amplitude.
 
 
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Influence of plastic parts on ultrasonic welding:
 
1. Ultrasonic waves propagate in plastic parts. Plastic parts absorb or attenuate ultrasonic energy more or less, which has certain influence on ultrasonic processing effect. Plastics generally have amorphous materials, hard rubber and soft according to hardness. The difference between the glue and the modulus is, in general, the high-hardness, low-melting plastic ultrasonic processing performance is superior to the low-hardness, high-melting plastic. Therefore, this involves the near-far problem of ultrasonic machining distance.
2. The influence of the processing conditions of plastic parts on ultrasonic welding, the different processing forms of plastic parts through injection molding, extrusion or blow molding, and different processing conditions will form factors that have certain influence on ultrasonic welding.
A. Humidity Defect: Humidity defects are generally formed during the process of making streaks or loose plastic parts. Humidity defects attenuate energy during welding, so that the sealing position seeps and lengthens the welding time. Therefore, the plastic parts with high humidity should be made before welding. Drying treatment. Such as polyoxymethylene.
B. The influence of the injection molding process: The adjustment of the parameters of the injection molding process will lead to the following defects: 1 dimensional change (shrinkage, bending deformation) 2 weight change 3 surface damage 4 poor uniformity
C. Storage period: After the plastic parts are injection-molded, they are generally placed for at least *4 hours before welding, so as to eliminate the stress and deformation of the plastic parts. Plastic parts that are molded from amorphous plastics may not meet this requirement.
D. Recycled plastics: The strength of recycled plastics is relatively poor, and the adaptability to ultrasonic welding is also poor. Therefore, if recycled plastics are used, various design dimensions should be considered as appropriate.