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The principle and theory of ultrasonic plastic welding machine

With the rapid development of the material industry, the application of composite materials such as plastics and metals with light weight, low friction, corrosion resistance and easy processing has received much attention. Various products of plastics have penetrated into various fields of daily life of people, and are also widely used in aviation, shipbuilding, automobiles, electrical appliances, packaging, toys, electronics, textiles and other industries. However, due to factors such as the injection molding process, a considerable number of plastic products with complicated shapes cannot be injection molded at one time, which requires bonding, and the plastic bonding and heat sealing processes that have been used for many years are quite backward, not only inefficient, but also bonding. The agent also has certain toxicity, causing problems such as environmental pollution and labor protection. The traditional process cannot be applied to the development needs of the modern plastics industry, so a novel plastic processing technology.Ultrasonic plastic welding machine need not add any adhesive, filler or solvent when welding plastic products, nor need not consume a lot of heat source. It has the advantages of simple operation, fast welding speed, high welding strength and high production efficiency. Therefore, ultrasonic welding technology is becoming more and more widely used.

The principle of ultrasonic plastic welding machine:

When ultrasonic waves act on the thermoplastic plastic contact surface, high-frequency vibrations of tens of thousands of times per second are generated. This high-frequency vibration reaches a certain amplitude, and the ultrasonic energy is transmitted to the weld zone through the upper weldment, because the weld zone is two the joints at the welded joints have a large acoustic resistance, so local high temperatures are generated. Moreover, due to the poor thermal conductivity of the plastic, it can not be dissipated in time and gather in the weld zone, so that the contact faces of the two plastics melt rapidly, and after a certain pressure, they are integrated into one. When the ultrasonic wave stops, let the pressure last for a few seconds to solidify it, thus forming a strong molecular chain for welding purposes, the welding strength can be close to the strength of the raw material. The quality of ultrasonic plastic welding depends on 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. The amplitude is determined by the transducer and the horn. These three quantities have a suitable value for each other. When the energy exceeds the appropriate value, the melting amount of the plastic is large, and the welding material is easily deformed; if the energy is small, the welding is difficult, and the applied pressure cannot be increased. This optimum pressure is the product of the length of the side of the welded portion and the optimum pressure per 1 mm of the edge. Ultrasonic welding is a high-tech technology for welding thermoplastic technology. Various thermoplastic rubber parts can be processed by ultrasonic welding without adding solvent, adhesive or other auxiliary products. The advantage is to increase productivity, reduce cost and improve product quality.

The generator generates 20KHZ, (or 15KHZ) high-voltage, high-frequency signal, through the conversion system, converts the signal into high-frequency mechanical vibration, which is applied to the workpiece of plastic products, through the working surface and the intrinsic intermolecular, the friction causes the temperature to be transmitted to the interface to rise. When the temperature reaches the melting point of the workpiece itself, the workpiece welding port is rapidly melted, and then filled in the gap between the interfaces. When the vibration stops, the workpiece is simultaneously cooled and fixed under a certain pressure to achieve the perfect welding.

How does the ultrasonic welding wrok?

The principle of ultrasonic welding is to convert 50/60 Hz current into 15, 20, 30 or 40 kHz by ultrasonic generator.　

The converted high frequency electrical energy is again converted same frequency mechanical movement by transducer,and then the mechanical movement is transmitted to the welding horn through a set of amplitude modulator equipment which can change the amplitude.

The welding horn transmit received vibrational energy to the joint of workpiece to be welded, in this area,the vibrational energy isconverted into thermal energy by friction to melt the palstic. The ultrasound is not only used to weld hard thermoplastics, but also process fabrics and films.