The sound that people hear is an acoustic signal with a frequency of 20-20000 Hz, and the sound waves above 20000 Hz are called ultrasonic waves. Sound waves propagate longitudinally according to a sinusoidal curve, that is, one layer is strong and the other layer is weak, and they propagate in turn. When a weak acoustic signal acts on a liquid, it will produce a certain negative pressure, that is, the volume of the liquid increases, the molecular gap in the liquid increases, and many tiny bubbles are formed. When a strong sound signal acts on a liquid, studies have proved that when ultrasonic waves act on the liquid, the rupture of each bubble in the liquid will produce a shock wave with huge energy, which is equivalent to a high temperature of several hundred degrees and up to several thousand atmospheres. This phenomenon is called "cavitation", and ultrasonic cleaning is to clean and scour the inner and outer surfaces of the workpiece by using the shock wave generated by the bursting of bubbles in liquid.
The second ultrasonic wave propagates in the liquid, so that the liquid vibrates with the cleaning tank at the ultrasonic frequency. When the liquid vibrates with the cleaning tank, it has its own natural frequency, that is, the frequency of sound waves, so people hear buzzing. If you have other unclear questions, please send an email to Miaoda @ 163.com and do my best.
1. What is ultrasound? Waves can be divided into three types, namely infrasound, sound wave and ultrasonic wave. The frequency of infrasound is below 20Hz; The frequency of sound wave is 20 Hz ~ 20kHz, and the frequency of ultrasonic wave is above 20 kHz. Infrasound waves and ultrasonic waves are generally inaudible to human ears. Ultrasonic wave has high frequency, short wave length, good directivity and strong penetration ability, which is the reason for designing and manufacturing ultrasonic cleaning machine.
2. How to finish cleaning with ultrasonic wave?
Ultrasonic cleaning is to use the socialization, acceleration and direct inflow of ultrasonic waves in liquid to directly and indirectly act on liquid and dirt, so that the dirt layer is dispersed, emulsified and peeled off to achieve the purpose of cleaning. Among the ultrasonic cleaning machines currently used, cavitation and direct current are widely used.
(1) Cavitation: Cavitation refers to the transmission of ultrasonic waves to liquid by high-frequency conversion mode of interaction between compression force and decompression of more than 20,000 times per second. When the pressure is reduced, vacuum nucleation bubbles are generated in the liquid, and when the pressure is applied, the vacuum nucleation bubbles are crushed by the pressure to generate strong impact force, thus peeling off the dirt on the surface of the cleaned object and achieving the purpose of accurate cleaning.
In the process of ultrasonic cleaning, the bubbles visible to the naked eye are not vacuum nuclear bubbles, but air bubbles, which inhibit cavitation and reduce cleaning efficiency. Only when the bubbles in the liquid are completely eliminated can the cavitation vacuum nuclear bubble achieve the best effect.
(2) Direct inflow: The phenomenon that ultrasonic waves flow in the direction of sound propagation in liquid is called direct inflow. When the intensity of sound wave is 0.5W/cm2, the naked eye can see a straight inflow, resulting in a flow perpendicular to the vibration surface, with a speed of about10 cm/s. Through this direct inflow, the micro-oil dirt on the surface of the object to be cleaned is stirred, and the cleaning liquid on the surface of the dirt also generates convection, and the dissolved liquid that dissolves the dirt is mixed with new liquid, which accelerates the dissolution speed and plays a great role in the transportation of the dirt.
(3) Acceleration: acceleration caused by liquid particles. For high-frequency ultrasonic cleaning machine, cavitation effect is very insignificant. At this time, the cleaning mainly depends on the ultra-precision cleaning of dirt by the accelerated impact of liquid particles under the action of ultrasonic waves.
3. Composition of ultrasonic cleaning machine: Ultrasonic cleaning machine is mainly composed of ultrasonic cleaning tank and ultrasonic generator. The ultrasonic cleaning tank is made of high-quality stainless steel with strong elasticity and corrosion resistance, and the bottom is equipped with an ultrasonic transducer vibrator; The ultrasonic generator generates high frequency and high voltage, which is transmitted to the transducer through the cable connection line. The transducer and the vibrating plate jointly generate high frequency resonance, so that the solvent in the cleaning tank is cleaned by ultrasonic.
Application of ultrasonic cleaning machine
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1, in general:
When sound waves in a certain frequency range act on the liquid medium, they can play a role in cleaning the workpiece. This cleaning technology has attracted wide attention from all walks of life since it came out. The application of ultrasonic cleaning greatly improves the working efficiency and cleaning effect. In the past, cleaning up dead corners, blind holes and inaccessible filth has always made people feel at a loss. The development and application of ultrasonic cleaning make this work easy. In recent years, with the rapid development of electronic technology, ultrasonic cleaning is also inseparable from our daily work. After several generations of evolution, the technology of ultrasonic cleaning machine is more advanced and the effect is more remarkable. Similarly, their prices are more and more accepted by the society and gradually widely used in all walks of life.
Ultrasonic waves propagate in liquid at the speed of 46,000 vibrations per second. Because ultrasonic wave is a kind of compressed longitudinal wave, with the use of driving medium, the pressure in liquid will change, producing countless tiny vacuum bubbles, thus producing cavitation effect. When bubbles burst under pressure, they will have a strong impact. At the same time, ultrasonic also has the function of emulsification and neutralization, which can effectively prevent the cleaned oil from attaching to the cleaned object again.
2. Scope of application:
Among all cleaning methods, ultrasonic cleaning is the most efficient and effective one. The reason why ultrasonic cleaning can achieve this effect is closely related to its unique working principle and cleaning method. We know that in production and life, there are many things to be cleaned, and there are also many types and links to be cleaned, such as removing pollutants from objects and dredging tiny holes. Common manual cleaning methods can not meet the requirements of irregular objects and hidden places, even steam cleaning and high-pressure water jet cleaning can not meet the requirements of high cleanliness. Ultrasonic cleaning can also kill bacteria, dissolve organic pollutants and prevent excessive corrosion, so ultrasonic cleaning is more and more widely used in various fields.
(1) machinery industry: removal of rust-proof grease; Cleaning of measuring tools; Oil and rust removal of mechanical parts; Cleaning of engine, carburetor and automobile parts; Dredging and cleaning of filters and screens.
(2) Surface treatment industry: degreasing and derusting before electroplating; Cleaning before ion plating; Phosphating treatment; Removing carbon deposits; Removing oxide scale; Transparent polishing paste; Metal workpiece surface activation treatment, etc.
(3) Instrument industry: high cleanliness of precision parts, cleaning before assembly, etc.
(4) Electronics industry: removing rosin and solder joints from printed circuit boards; Clean mechanical and electronic components, such as high-voltage contacts.
(5) Medical industry: cleaning, disinfection and sterilization of medical instruments, cleaning of experimental instruments, etc.
(6) Semiconductor industry: high cleanliness cleaning of semiconductor wafers.
(7) Watch head and accessories industry: removing sludge, dust, oxide layer, polishing paste, etc.
(8) Chemical and biological industries: cleaning and descaling of experimental instruments.
(9) Optical industry: degreasing, sweating and dust removal of optical devices.
(10) Textile printing and dyeing industry: cleaning textile spindles and spinnerets.
(1 1) Petrochemical industry: cleaning and dredging of metal filters, cleaning of chemical containers and exchangers, etc.
3. Advantages of ultrasonic cleaning:
Compared with other cleaning methods, ultrasonic cleaning machine shows great advantages. Especially in specialized and collectivized production enterprises, ultrasonic cleaning machines have gradually replaced the traditional process methods such as soaking, brushing, pressure cleaning, vibration cleaning and steam cleaning. The high efficiency and high cleanliness of ultrasonic cleaning machine benefit from the penetration and cavitation shock wave generated by its sound wave when it propagates in the medium. Therefore, it is easy to clean the parts with complex shapes, holes and gaps. For general degreasing, rust prevention, phosphating and other processes, it only takes two or three minutes under the action of ultrasonic waves, which can increase the speed by several times to dozens of times compared with traditional methods, and the cleanliness can also reach a high standard. It can be seen that in many occasions that require high surface quality and productivity of products, other treatment methods are difficult to achieve or irreplaceable.
Its advantages are summarized as follows:
(1) The cleaning speed is fast, the cleaning effect is good, the cleanliness is high, the cleanliness of the workpiece is consistent, and there is no damage to the surface of the workpiece.
(2) It is safe and reliable to clean the deep holes, thin seams and hidden places of the workpiece without touching the cleaning liquid by hand.
(3) Save solvent, heat energy, site and labor.
4. Precautions:
When there is no water or solvent in the ultrasonic tank of the ultrasonic cleaning machine, never start it, which will cause idle vibration and the vibrating head will be scrapped or damaged. The correct operation and maintenance of ultrasonic equipment should be managed by special personnel.