The Origin, Principle, Technical Requirements Of Ultrasonic Metal Welding Machine

2021-03-31 10:34:53

Ultrasonic metal welding was discovered by chance in the 1930s. At the time, when the current spot welding electrode was added to the ultrasonic vibration test, it was found that the current could not be welded, and the ultrasonic metal cold welding technology was developed. Although ultrasonic welding was discovered earlier, the mechanism of action has not been clear so far. It is similar to friction welding, but with the difference that the ultrasonic welding time is short and the temperature is lower than recrystallization; it is not the same as the pressure welding because the applied static pressure is much smaller than the pressure welding. It is generally believed that in the initial stage of the ultrasonic welding process, the oxide is tangentially vibrated out of the metal surface, and the protruding portion of the rough surface generates repeated micro-welding and destruction processes to increase the contact area and simultaneously increase the temperature of the soldering zone. High, plastic deformation occurs at the interface of the weldment. In this way, under the action of the contact pressure, the solder joints are formed when they approach each other to a distance at which the atomic attraction can act. The welding time is too long, or the ultrasonic amplitude is too large, so that the welding strength is reduced or even destroyed.Ultrasonic metal welding is to transfer tens of thousands of high-frequency vibration waves per second to the surface of two metal workpiece to be welded, and then apply a certain pressure to make the metal surface friction and form the fusion between molecular layers, so as to achieve the purpose of welding.

What are the differences between ultrasonic metal welding machine and ultrasonic plastic welding machine?

1. First of all, it works in different ways. Generally, the vibration direction of the welding head in ultrasonic plastic welding is perpendicular to the welding position, and the vibration direction of the welding head in ultrasonic metal welding is parallel to the welding position. In some special cases, plastic welding can also be used in parallel direction, such as thin plastic parts.

2. Secondly, as ultrasonic wave is used to weld metals, higher requirements are put forward for ultrasonic welding technology; Compared with ordinary plastic welding, the requirements of power capacity, power density, stability and automatic control are not the same level. At present, domestic ultrasonic plastic welding generators are basically self-excited circuit, the typical representative is: 8400, 8700 full bridge circuit and Taiwan machine commonly used half bridge circuit, with a remarkable characteristic of tuning inductance. If the existing mature technology for plastic welding is directly transferred to the metal welding, its technical deficiencies will lead to unstable use of products; Its only advantage is the low price, but for the high requirements of metal welding itself, this advantage is very pale.

1. High power capacity, stable ultrasonic generator:

The first requirement of stable ultrasonic generator is: automatic frequency tracking. Automatic frequency tracking can ensure that the transducer system can work in the resonant state, i.e. maximize the welding head amplitude. The basic requirement of metal welding is to adopt automatic frequency tracking technology and not to need frequency modulation when changing the mould and working. There are adjustable inductor manual frequency of the equipment, basically can not meet the requirements.

Stable ultrasonic generator also requires: constant amplitude function and amplitude stepless adjustable. Constant amplitude function, which can ensure the consistency of welding, is the key to stable production; Stepless amplitude adjustment is essential for the purpose of the equipment, such as welding both copper and aluminum materials on the same equipment through parameter adjustment.

High power capacity: compared with plastic welding, metal welding requires high energy density, so it must have a relatively high power capacity. For example, a machine of 20kHz basically requires a power capacity of more than 3000W. A lot of companies make false claims about power capacity, so we only need to compare it with the plastic welders they make, because no one believes that plastic welders are labeled too high.

2. High quality welding head: metal welding as an industrial use, the inevitable requirements of high life of the welding head.

3. High quality transducer: for example, a transducer of 20kHz should be able to withstand a long-term load of more than 3kw. A lot of companies have transducers, transducers that are welded to ordinary plastic, that are hard to tell from the outside, and that's irresponsible.

4. Quality control system: with three basic control modes of welding energy, time and height, various quality control software can meet different requirements.

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