[Ultrasonic welding machine] the role of the transducer on ultrasonic welding

The welding specification of ultrasonic welding machine, especially the amplitude of ultrasonic vibration and the frequency of output current, has a great influence on the stability of joint quality. The welding characteristics with the first thermal cycle, the stability of the amplitude is low, this welding in the case of small ultrasonic vibration power. Because, in order to obtain the amplitude that can guarantee the welding quality, it is necessary to weld under the condition of near resonance. In this case, of course, even if the natural frequency of the mechanical vibration system changes very small, the amplitude will be significantly reduced.

Because the welding quality is very sensitive to changes in external conditions, the resulting joint quality is very unstable. Under actual welding conditions, the natural frequency of the vibration system will also vary significantly due to the formation of a sufficiently strong joint between the two welds under the vibration head and at the contact point on the table surface.

With the increase of the power of ultrasonic transducer, the amplitude change of ultrasonic welding process is correspondingly small, and the joint strength has a greater stability. There are two reasons for this situation. Firstly, the load change has little effect on the high-power ultrasonic transducer; Second, the mass of the object attached to the vibrating transfer bar is relatively small due to the continuous failure of the connection joint at the contact point at a contact point. Therefore, the power of ultrasonic transducer can be increased to improve the stability of the joint quality.

The relationship we discuss between the amplitude and the change in the system's natural frequency will occur only if the frequency of the generator's output current is constant. When the current frequency changes occasionally, the amplitude variation characteristics become very complex, which reduces the quality stability of the joint. When a generator can automatically adjust the current frequency according to the natural frequency of the vibration system, the stability of operation will be completely different. Under the working condition of the stabilizer, the amplitude is very stable, reaching the larger value of the sensor, and improving the stability of the joint quality. When we adjust the generator to the same power, we can solder thicker welds.