What is the function of the welding head of the ultrasonic welding machine
Ultrasonic welding machineThe function of the welding head is to manufacture specific plastic parts to meet the requirements of the shape and processing range of the plastic parts. The transducer, horn, and welding head are designed according to the half-wavelength of the working ultrasonic frequency, and their size and shape should be specially designed. Any change may lead to changes in frequency and processing effects, and requires professional production. Depending on the material used, the amount of durability will vary. The materials suitable for ultrasonic transducers, horns and welding heads are: titanium alloy, aluminum alloy, alloy steel, etc. Due to the high-frequency continuous vibration of ultrasonic waves around 20kHz, the requirements for materials are very high, which is unacceptable by ordinary materials of.
When ultrasonic waves propagate in the medium, due to the interaction between the ultrasonic waves and the medium, the medium undergoes physical and chemical changes, resulting in a series of mechanical, thermal, electromagnetic and chemical ultrasonic effects, including the following four effects:
1. Mechanical effect:
The mechanical action of ultrasound can promote liquid emulsification, gel liquefaction and solid dispersion. When a standing wave is formed in the ultrasonic fluid medium, due to the action of mechanical force, the small particles suspended in the fluid condense in the nodes and form periodic accumulation in the space. When ultrasonic waves propagate in piezoelectric materials and magnetostrictive materials, the mechanical action of ultrasonic waves causes the excitation electric polarization and induced magnetization.
When ultrasonic waves act on the liquid, a large number of small bubbles are generated. One reason is that the local tensile stress in the liquid forms a negative pressure. The decrease in pressure makes the gas originally dissolved in the liquid supersaturate, and then escape from the liquid and become a small bubble. Another reason is that strong tensile stress "tears" the liquid into cavities, called cavities. There is liquid vapor or another gas dissolved in the liquid in the cavity, even in a vacuum. The small bubbles formed by cavitation move, grow, or burst with the vibration of the surrounding medium. When the liquid enters the bubbles, it will produce high temperature, high pressure and shock waves. Internal friction related to cavitation can form charges in bubbles and cause light emission due to discharge. Liquid ultrasonic treatment technology is mainly related to cavitation.
3. Thermal effect:
Due to the high frequency and high energy of ultrasound, it will produce obvious thermal effect when absorbed by the medium.
4. Chemical effects:
The effect of ultrasound can promote or accelerate certain chemical reactions. For example, after ultrasonic treatment, pure distilled water will generate hydrogen peroxide, after ultrasonic treatment, nitrogen in the water will generate nitrous acid, and the dye aqueous solution will change color or fade after ultrasonic treatment. These phenomena are always accompanied by cavitation. Ultrasound can also accelerate the hydrolysis, decomposition and polymerization of many chemical substances. Ultrasound also has obvious effects on photochemistry and electrochemistry. After ultrasonic treatment, the characteristic absorption bands of amino acids and other organic substances disappeared, indicating that cavitation changed the molecular structure.