Matching of Ultrasonic Transducer and Ultrasonic Generator

Let the ultrasonic transducer, generator ultrasonic drive power supply and ultrasonic mold cooperate well to form a complete ultrasonic equipment, which can be referred to as matching. Since the impact of matching on the performance of the whole machine is decisive, it is necessary to emphasize the importance of matching. The most important factor for matching is the capacitance of the ultrasonic transducer, followed by the frequency of the transducer.


It should be emphasized that the ultrasonic transducer itself is not an energy generator, it is just an energy converter. It converts electrical energy into sound energy and it can convert (output) a large amount of energy on the premise that the input and output are well matched.


1. Input matching of ultrasonic transducer and generator ultrasonic


Input matching refers to the matching of the transducer with the generator ultrasonic. If the output matching is good but the input matching is not good, the transducer is weak and the welding is not strong. If the output matching is not good and the input matching is good, the transducer will be overloaded, resulting in wafer dislocation, cracking, breaking, screw breakage, aluminum cracking or burning of the power tube of the electric box. For example, if a car is slammed on the gas pedal in neutral, the engine must be easily damaged. There are four main aspects of matching between ultrasonic transducer and driving power supply, namely impedance matching, frequency matching, power matching and capacitive reactance matching.


2. Frequency matching of ultrasonic transducer and generator ultrasonic


Frequency matching is also very important. This is first because the ultrasonic transducer can only work at its resonant frequency, so the drive power supply, horn, and welding die (tool head) should all work at this frequency. Generally speaking, it is hoped that the difference does not exceed ±0.1khz at most and it is better if it is smaller. It is recommended that the frequency of the matching welding die (welding head) be lower than the frequency of the vibrator by about 0.1khz (small signal frequency). That is to say, if the frequency measured by the small signal of the original vibrator is 14.85khz, it is ideal to measure the frequency of 14.75khz after connecting the mold. At the same time, it should be considered that when the ultrasonic transducer is connected to the horn and the die head, the peak value of the resonance frequency of the system will become very sharp. That is, the bandwidth is very narrow, the mechanical quality factor is large, and a little frequency offset will cause a large increase in impedance. It is manifested in the drive power supply that the power supply (amplitude meter electric power) is very large or overload protection. If it happens to be no-load adjustment at this time, it is likely to cause the wafer to be dislocated, broken, or the center screw to be broken.


3. Power matching and impedance matching of ultrasonic transducer and generator ultrasonic


Power matching and impedance matching are mainly considering that the ultrasonic welding system works in gaps and the load changes greatly. There must be enough power output during welding and the minimum amplitude should be controlled at no-load. Otherwise, as mentioned earlier, the input will be large at no load and the transducer will be damaged. When the power is not up at full load, it is useless if the welding is not firm.

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