History of Ultrasonic Development
Ultrasonic waves are a type of sound wave with a frequency higher than 20000Hz (Hertz), which is the propagation process of mechanical vibration in a medium. They have high frequency, short wavelength, good directionality, strong penetration, high power, cavitation and a series of special physical properties. At the beginning of the 20th century, humans began to develop and promote ultrasound technology, which played a huge role in fields such as medicine, military, industry, and agriculture. It has a wide range of basic applications in various disciplines and industries such as aerospace, metallurgy, machinery, agriculture, biology, materials, and food. Ultrasonic technology, as a fundamental interdisciplinary field, will have a broader development and application prospect as research deepens.
Principle of Ultrasonic Welding
Ultrasonic welding is the process of converting 50/60 Hz current into 15, 20, 30, or 40 KHz electrical energy using an ultrasonic generator. The converted high-frequency electrical energy is converted back into mechanical motion of the same frequency through a transducer, and then the mechanical motion is transmitted to the welding head through a set of amplitude changing rod devices. The welding head transfers the received vibration energy to the joint of the workpiece to be welded, where the vibration energy is converted into heat energy through friction, melting the plastic. Ultrasonic waves can not only be used for welding hard thermoplastic plastics, but also for processing fabrics and films. The heat energy comes from the reciprocating movement of a workpiece on another surface with a certain displacement or amplitude under a certain pressure. Once the expected welding level is reached, the vibration will stop, while there will still be a certain amount of pressure applied to the two workpieces, causing the just welded part to cool and solidify, thus forming a tight bond.
Introduction to the Structure of Ultrasonic Plastic Welding Machine
The main components of an ultrasonic plastic welding machine include:
1、 Power control system
Control the working time and sequence of the ultrasonic generator and pneumatic transmission system to achieve automation of the entire welding process.
2、 Pneumatic pressure system
Including filters, pressure reducing valves, oil mist devices, commutators, throttle valves, cylinders, etc., it drives the ultrasonic transducer vibration system to move up and down to the appropriate working position.
3、 Ultrasonic generator
The mainstream ultrasonic generators use self-excited power oscillators with certain frequency tracking capabilities. Some high-end products adopt phase-locked frequency automatic tracking circuits to achieve fully digital management.
4、 Ultrasonic transducer
It consists of two parts: ultrasonic transducer and ultrasonic amplitude rod. Generally, a longitudinal vibration transducer clamped with bolts is used, and the amplitude rod provides system support and amplitude amplification effect. Ultrasonic generator
5、 Ultrasonic mold welding head
There are two types: one with amplitude amplification and one without amplitude amplification. The acoustic system tool head is usually made of aluminum alloy and carbon steel, and titanium alloy material is also used. Ultrasonic transducer
6、 Other components include racks, workbenches, etc.
