Production and maintenance of ultrasonic cleaning transducer molds

Piezoelectric ultrasonic transducer means that the vibration frequency is greater than 20KHz, and the number of vibrations per second (frequency) is very high, which exceeds the upper limit of the human ear (20000Hz). People call this inaudible sound wave ultrasonic. Ultrasound and audible sound are essentially identical. They have a common point of mechanical vibration, which is usually propagated in an elastic medium in the form of a longitudinal wave. It is a form of energy propagation, and the difference is that the ultrasonic frequency is high. The wavelength is short, and it has good beamability and directivity along a straight line within a certain distance. In 2013, the frequency range used for abdominal ultrasound imaging is between 2∽5MHz, usually 3∽3.5MHz (one vibration per second) 1 Hz, 1 MHz = 10 ^ 6 Hz, that is, 1 million vibrations per second, and the frequency of audible waves is between 16 and 20,000 Hz.

Two main parameters of ultrasound：

Two main parameters of piezo ceramic ring: Frequency: F ≥ 20KHz; Power density: p = Transmit power (W) / Emission area (cm2); Usually p ≥ 0.3w / cm2; Ultrasonic waves propagating in liquid can stain the surface of the object .The principle of "cleaning" can be explained by the phenomenon of "cavitation": when the ultrasonic wave propagates in the liquid to a pressure of one atmosphere, the power density is 0.35w/cm2, and the ultrasonic wave pressure peak can reach the vacuum or negative pressure, but in fact ,no negative pressure exists, so a large pressure is generated in the liquid, which breaks the liquid molecules into voids and cavitation nuclei. This cavity is very close to the vacuum, which ruptures when the ultrasonic pressure is reversed to the maximum, and the strong impact due to the rupture strikes the dirt on the surface of the object. 

This shock wave phenomenon caused by the cracking of numerous small cavitation bubbles is called the "cavitation" phenomenon.The design and production of ultrasonic molds must be very simple. Don't be misled, when using a mishandled or untuned weld head, it will cost you a lot of production -- it will destroy the welding effect, and even more serious will directly lead to the transducer or happen Damage to the device. Therefore, the design of the ultrasonic mold is not as simple as its shape. On the contrary, it requires a lot of professional knowledge and skills - how to ensure the most economical work of the ultrasonic textile welding transducer head? How to ensure that the welding head can effectively convert the mechanical vibration of the transducer? Transfer to the workpiece to form a consistently stable weld - the ultrasonic mold is one of the most technically deep aspects of ultrasonic technology. Different tool heads are required for different welding objects. Whether it is near-field welding or transmission welding, only a half-wavelength tool head can achieve the maximum amplitude of the welding end face. The tool head has two kinds of amplitude and no amplitude amplification.

The tool head of the acoustic system for plastic ultrasonic welding transducer is usually made of aluminum alloy. The end face is plated with hard alloy. When the power is high, it is also made of titanium alloy material. In this case, the fatigue strength of the material is more than twice as high as that of the aluminum alloy.Because the ultrasonic welding head works under high frequency vibration, it should try to maintain a symmetrical design to avoid the unbalanced stress and lateral vibration caused by the asymmetry of sound wave transmission. Unbalanced vibration can cause the hair to heat and break. Ultrasonic welding is applied to different industries and has different processing precision requirements. For particularly thin workpieces such as lithium ion battery pole pieces and tab welding, gold foil coating, etc., the machining accuracy is very high, and high precision is required. The processing equipment is processed so that the molds produced meet the requirements for use. Ultrasonic welding requires metal materials to have good flexibility (small mechanical loss during sonic transmission). Therefore, the most commonly used materials are aluminum alloy and titanium alloy materials, which are the main reasons for ensuring the life of ultrasonic molds in welding products. First, the process of completing the mold is complicated. Therefore, it is not only the design of the mold engineer that the material must be carefully selected, but also the material that the product requires to be used to avoid inadvertent influence on its timeliness and quality of vibration cleaning transducer.