Principle Of Ultrasonic Welding Machine
Principle of ultrasonic plastic welding: When ultrasonic waves act on the contact surface of thermoplastics, high-frequency vibrations of tens of thousands of times per second will be generated. This high-frequency vibration with a certain amplitude transmits ultrasonic energy to the welding area through the upper weldment. Due to the large acoustic resistance in the welding area, that is, the interface between the two welding parts, local high temperature will be generated, and due to the poor thermal conductivity of the plastic, it cannot be dissipated in time, and it gathers in the welding area, resulting in the rapid melting of the contact surface of the two plastics, adding a certain pressure. and then merged into one. When the ultrasonic wave stops working, let the pressure continue for a few seconds to make it solidify and form a solid molecular chain, so as to achieve the purpose of welding, and the welding strength can be close to the strength of the raw materials.
Ultrasonic welding process:
1. Welding Welding refers to the butt welding of plastic parts. The design of the two joint surfaces is very important to obtain the best welding effect. The use of various designs depends on many factors, such as plastic type, part geometry and welding requirements (i.e. tack, strength seal, etc.).
2. Insertion Insertion is a method of inserting metal components in thermoplastic parts. During the welding process, ultrasonic vibration is transmitted through the element to the interface between the metal insert and the plastic, and the heat generated by the metal insert against the plastic vibration causes the plastic to melt immediately, thereby driving the insert into place, and the melted plastic flows into the insert saw teeth Shape protrusions and undercuts, the inserts are cured when the plastic cures, and several inserts can be inserted at the same time.
3. Riveting Ultrasonic riveting is an assembly method in which a plastic column is melted and then shaped to fix another component, which is usually made of a different material. The design of the piling and the cavity is determined by the requirements of the application and the physical dimensions of the piling. But the fundamentals of each design are the same. That is, the initial contact area between the welding head and the pile should be kept to a minimum so that the concentrated energy can be rapidly melted. Ultrasonic riveting generally requires high amplitude and low pressure. Some materials with high melting temperature are prone to form fragile pile heads. In this case, standard column ends, high pressure, high amplitude and high trigger pressure can be used to obtain better results. . When welding, the weld head should be lowered onto the pile at a moderately slow stroke speed to allow time for the material to melt and prevent the pile from deforming due to pressure.
4. Swaging uses ultrasonic energy to melt plastic to form a raised part to mechanically fix another part in the assembly. This processing method is called swaging. The deformation method of swaging allows plastics to be forged into a variety of shapes, and the forming technology is not limited to circular cross-sections. In general, materials that are easy to swage or form include polypropylene, polyethylene, polymethylpentene, propylene glycol, styrene copolymers, polystyrene, and cellulose. Relatively hard materials are not as easy to mold. forging.
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