Principle of 20KHZ ultrasonic plastic welding machine
The principle of ultrasonic plastic welding is to convert the 20KHZ (or 15KHZ) high-voltage high-frequency signal generated by the generator into high-frequency mechanical vibration through the energy conversion system, and then apply it to the plastic workpiece and cause transfer through the surface and internal molecular parts. The interface temperature rises. When the temperature reaches the melting point of the target itself, the interface of the workpiece will melt rapidly and then fill the gap between the interfaces. When the vibration stops, it is under a certain pressure at the same time. After cooling and forming, the welding can be completed.
When ultrasonic waves act on the contact surface of thermoplastics, tens of thousands of high-frequency vibrations are generated every second. This high-frequency vibration with a certain amplitude will transfer the ultrasonic energy to the welding area through the upper weldment. Because the welding area is two. The acoustic resistance at the welding interface is very large, so local high temperatures are generated. In addition, due to the poor thermal conductivity of the plastic, it cannot be distributed and gathered in the welding area in time for a period of time, which causes the contact surface of the two plastics to melt rapidly after a certain pressure is applied. , It merges into one. When the ultrasound stops, let the pressure continue for a few seconds to solidify and shape, thereby forming a solid molecular chain to achieve the purpose of welding, and the welding strength can be close to the strength of the raw material. The quality of ultrasonic plastic welding depends on three factors: the amplitude of the welding head of the transducer, the pressure applied and the welding time. The welding time and welding head pressure can be adjusted, and the amplitude is determined by the sensor and welding head. The interaction of these three quantities has an appropriate value. When the energy exceeds a proper value, the melting amount of the plastic is large and the welding material is easily deformed; when the energy exceeds the proper value, the welding material is easily deformed. When the energy exceeds an appropriate value, the welding material is easily deformed. When the energy exceeds an appropriate value, the welding material is easily deformed. If the energy is small, it is not easy to weld firmly, and the pressure applied cannot be too large. The pressure is the product of the side length of the welded part and the pressure per 1 mm edge.
Hangzhou Altrasonic's ultrasonic welding machine and ultrasonic welding machine use high-density energy generated by ultrasonic high-frequency mechanical vibration. Produce plastic deformation on the surface of the workpiece and destroy the layer under pressure so that the welded metals are physically connected at room temperature. The heat conduction efficiency is better, and ultrasonic welding has certain advantages in material cost. The center frequency of the ultrasonic welding machine is 20KHz, 40KHz, etc. The working frequency of the welding machine mainly depends on the mechanical resonance frequency of the transducer, welding head and welding head. Adjust the frequency of the generator according to the mechanical resonance frequency to achieve consistency and make the welding head resonate. Each part is designed as a half-wavelength resonator. Ultrasonic welding machines often encounter some bad problems when welding products, these problems will affect the production process and damage the plastic surface of the product! How to repair this damage?
After turning on the ultrasonic welding machine, it will automatically test and run once. The end point of the actual operating frequency of the ultrasonic component will be stored and the current frequency will be displayed. Design frequency: First determine the approximate frequency of the transducer and cutter head, and then input the approximate frequency to the setting. (For example, it is estimated that the transducer combination is about 20KHz, and the set frequency can be 20~20.5KHz): Store the actual working frequency, and display the current frequency at the end of each welding. After welding, the frequency drift caused by the heat of the welding head or other factors is always in the best resonance state and stored.