The Working Principle Of Ultrasonic Welding Machine
What is the working principle of ultrasonic welding machine
Sounds when an object vibrates. Scientists call the number of vibrations per second the frequency of sound, and its unit is hertz. The frequency of sound waves that can be heard by our human ears is 16 Hz to 20 kHz (kilohertz). Therefore, when the vibration of an object exceeds a certain frequency, that is, above the upper limit of the human ear's hearing threshold, people cannot hear it. Such sound waves are called "ultrasonic waves". The ultrasonic frequency used for medical diagnosis is usually 1 to 5 MHz.
Although humans cannot hear ultrasound, many animals have this ability. They can use ultrasound to "navigate", hunt food, or avoid dangerous objects. You may have seen many bats flying back and forth in the courtyard on summer nights. Why do they fly without light without getting lost? The reason is that bats can emit 20,000 to 100,000 hertz of ultrasound, which is like an active "radar station". Bats use this "radar" to determine whether they are flying insects or obstacles.
We humans did not learn to use ultrasound until World War I. This is the use of the sonar principle to detect targets in the water and their states, such as the position of submarines. At this time, people send a series of ultrasonic waves with different frequencies to the water, and then record and process the reflected echo. From the characteristics of the echo, we can estimate the distance, shape and dynamic change of the detected object. The earliest use of ultrasound in medicine was in 1942. The Austrian doctor Dusick first used ultrasound technology to scan brain structures. Later in the 1960s, doctors began to use ultrasound to detect abdominal organs. Ultrasound scanning technology has become an indispensable tool for modern medical diagnosis.
The working principle of medical ultrasound examination is similar to that of sonar, that is, the ultrasound is emitted into the human body. When it encounters the interface in the body, it will reflect and refract, and it may be absorbed and attenuated in human tissues. Because the shape and structure of various tissues of the human body are different, the degree of reflection and refraction and the degree of absorption of ultrasonic waves are different. Doctors use the characteristics of the wave pattern, curve, or image reflected by the instrument to distinguish them. they. In addition, combined with anatomical knowledge, normal and pathological changes, you can diagnose whether the examined organ is diseased.
Sound waves with frequencies above 20KHz (Hertz). The branch of acoustics that studies the generation, propagation, and reception of ultrasound, as well as various ultrasonic effects and applications, is called ultrasound. The ultrasonic generating devices include mechanical ultrasonic generators (such as air whistle, whistle, liquid whistle, etc.), electric ultrasonic generators made by the principles of electromagnetic induction and electromagnetic action, and the use of piezoelectric crystals' electrostrictive effect and ferromagnetism. Electroacoustic transducers made of the magnetostrictive effect of matter, etc.
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