Introduction to Ultrasonic Transducers
The ultrasonic transducer is a sandwich component made of lead zirconate titanate piezoelectric ceramic material. Most ultrasonic cleaners use horn-type ultrasonic transducers, which increase the coupling and sound radiation efficiency by enlarging the radiation surface of the front cover. With proper prestress, the transducer has good electromechanical conversion efficiency under the conditions of high power and high amplitude.
1. development path
At the beginning of the 20th century, the development of electronic technology enabled people to use the piezoelectric and magnetostrictive effects of certain materials to manufacture various electromechanical transducers. In 1917, French physicist Lang Zhiwan made a sandwich ultrasonic transducer using natural piezoelectric quartz and used it to detect submarines on the sea floor. With the continuous development of ultrasonic applications in various fields of military and national economy, magnetostrictive transducers with greater ultrasonic power and electric, electromagnetic and electrostatic transducers for various purposes have appeared. Ultrasonic transducer.
2. Material classification
There are usually two types of ultrasonic transducers: magnetostrictive transducers and piezoelectric crystal transducers.
There are magnetostrictive nickel sheet transducers and ferrite transducers.
The electro-acoustic conversion efficiency of ferrite transducers is low. Generally, after one or two years of use, the efficiency will decrease and the electro-acoustic conversion capability will almost be lost. The process of nickel chip transducer is complicated and expensive, so it is rarely used so far.
Piezoelectric crystal type
The most mature and reliable device is the piezoelectric effect, which realizes the mutual conversion of electric energy and sound energy, and is called a piezoelectric transducer. The piezoelectric effect of the material converts electrical signals into mechanical vibrations. This kind of transducer has high electroacoustic conversion efficiency, cheap raw materials, convenient production and not easy to age.
Commonly used materials are quartz crystal, barium titanate and lead zirconate titanate. The expansion and contraction of the quartz crystal is too small, and the voltage of 3000V produces a deformation lower than 0.01um. The piezoelectric effect of barium titanate is 20-30 times that of quartz crystal, but its efficiency and mechanical strength are not as good as quartz crystal. Lead zirconate titanate has the advantages of both, and can usually be used as a sensor for ultrasonic cleaning, flaw detection and low-power ultrasonic processing.
Central piezoelectric ceramic element
Front and rear metal cover
This kind of sandwich transducer will generate stable ultrasonic waves when the load changes. This is the most basic and main method to obtain the power ultrasonic drive source.
4. Before leaving the factory, all ultrasonic transducers have been inspected and qualified.
Use a dedicated vibration head impedance tester to test the main parameters of the vibrating head: Fs R1 C0 Qm, perform sub-inspection on the vibrating head, the sub-inspection rules are: impedance ≤25Ω is qualified, impedance difference is within 10Ω, and frequency <±0.5KHz , The first gear is within 100Hz.
Vibrating head: 1. There are matching parameters 2. Both have been aging for 3 months, and the function is stable.