The role of ultrasonic welding machines on thermoplastics

    When the ultrasonic welding machine acts on the thermoplastic plastic contact surface, it will generate tens of thousands of high-frequency vibrations per second. This high-frequency vibration reaches a certain amplitude, and the ultrasonic energy is transmitted to the weld zone through the upper weldment. That is, the sound resistance at the interface of the two welds is large, so local high temperature is 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. The interaction of these three quantities has a suitable value. 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 not easy, and the applied pressure cannot be too large. 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.

    The control system consists of a time relay or an integrated circuit time timer.

    The main functions are:

    The first is to control the operation of the gas transmission system. The ultrasonic welding machine opens the gas path valve under the timing control during the welding. The cylinder pressure causes the welding head to descend, and the workpiece is pressed under a certain pressure. When the welding is completed, the pressure is maintained for a period of time. Then the control system reverses the gas path valve to cause the welding head to return to reset;

    The second is to control the working time of the ultrasonic generator. The southern force control system automates the entire welding process. When the operation starts, only the start button generates a trigger pulse, which can be automatically completed in the whole welding process. The order of the whole control system is: power start-trigger control signal pneumatic transmission system, cylinder pressure welding head descends and presses the welding trigger ultrasonic generator work, emits ultrasonic waves and maintains a certain welding time to remove ultrasonic emission to maintain a certain pressure time to depressurize The welding head is lifted and the welding is over.