Application Principle Of Ultrasonic In Plastic Welding

1. Application principle of ultrasonic in plastic welding:

Ultrasonic waves used in plastic processing, several existing operating frequencies are 15KHZ, 18KHZ, 20KHZ, 40KHZ. The principle is to use the peak position of the longitudinal wave to transmit the amplitude to the gap of the plastic part. Under the condition of pressure, the molecules of the two plastic parts or other parts in contact with the plastic part collide with each other to melt, so that the contact plastic is fused. Processing purposes.

2, the composition of the ultrasonic welder

The ultrasonic welding machine is mainly composed of the following components: generator, pneumatic part, program control part, and transducer part.

The main function of the generator is to convert the power supply of the power frequency 50HZ into a high-frequency (for example, 20KHZ) high-voltage electric wave by using an electronic circuit.

The main function of pneumatics is to complete the pressure, pressure and other pressure work needs during the processing.

The program control controls the workflow of the whole machine to achieve consistent processing results.

The transducer is used to convert the high-voltage electric wave generated by the generator into mechanical vibration, which is transmitted, amplified, and reaches the machined surface.

3. The transducer consists of three segments: Transducer (TRANSDUCER); Amplifier (also known as secondary rod, horn, BOOSTER); Weld head (also known as welding, HORN or SONTRODE).

1 Transducer (TRANSDUCER): The function of the transducer is to convert electrical signals into mechanical vibration signals. There are two physical effects that can be applied to convert an electrical signal into a mechanical vibration signal. A: Magnetostrictive effect. B: The inverse effect of the piezoelectric effect. The magnetostrictive effect is more commonly used in early ultrasonic applications. The advantage is that the power capacity can be made large; the disadvantage is that the conversion efficiency is low, the production is difficult, and it is difficult to mass-produce industrial production. Since the invention of the Langevin piezoelectric ceramic transducer, the application of the piezoelectric effect counter effect has been widely adopted. Piezoelectric ceramic transducers have the advantages of high conversion efficiency, mass production, etc. The disadvantage is that the power capacity produced is small. Existing ultrasonic machines generally use piezoelectric ceramic transducers. Piezoelectric ceramic transducers are made by sandwiching piezoelectric ceramics with two metal front and rear load blocks and tightly connecting them by means of screws. The amplitude of a typical transducer output is about 10 μm.

2 Welding head (HORN): The function of the welding head is to make for a specific plastic part, in accordance with the shape and processing range of the plastic part.

The transducers, horns, and horns are designed to be half the wavelength of the ultrasonic frequency at work, so their size and shape are specially designed; any changes may cause changes in frequency and processing effects. Professional production. Durability varies depending on the materials used. The materials suitable for ultrasonic transducers, horns and welding heads are: titanium alloy, aluminum alloy, alloy steel, and the like. Since the ultrasonic waves are constantly vibrating at a high frequency of about 20 kHz, the material requirements are very high and are not affordable for ordinary materials.