Development of Vacuum Cleaning Technology

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1. Take out the air in the cleaning agent to reduce the attenuation of ultrasonic waves. In order to improve the cleaning effect, ultrasonic technology is generally used in the cleaning machine, and the ultrasonic vibrator vibrates tens of thousands of times per second to emit more than 100000 times the sound pressure that can be heard by the human ear. In the case of cleaning, the ultrasonic wave is radial in the liquid, which makes the cleaning liquid flow and produces a large number of vacuum bubbles. This phenomenon is the effect of cavitation. The liquid flow generated by this cavitation and the energy generated by the instantaneous explosion of tens of thousands of high-pressure vacuum bubbles constantly impact the surface of the object to be cleaned, causing the dirt in the surface and the gap to peel off rapidly. However, under normal pressure, the air particles dissolved in the cleaning agent produce bubbles when they encounter ultrasonic waves, and the cavitation effect of ultrasonic waves will be greatly attenuated, and the cleaning effect will be weakened. In a vacuum,Cleaning agentThe gas in it will be removed, thus avoiding the attenuation of ultrasonic waves. This effect can be verified from the aluminum foil experiment: in the cleaning tank were added without vacuum degassing and after vacuum degassinghydrocarbon cleaning agentThe aluminum foil was cleaned with ultrasonic waves of the same power for one minute. As a result, the cleaning agent without degassing showed a slight vibration, and the aluminum foil was basically unchanged. And after vacuum degassing cleaning agent violent vibration, aluminum foil soon appeared many holes.
2. Eliminate the air in the surface and pores of the workpiece to improve the cleaning effect. In traditional cleaning, the cleaning effect is not ideal is often because the air in the blind hole, rough surface and small gap can not be discharged, affecting the infiltration of cleaning agent, resulting in cleaning blind area. After the application of vacuum technology, the air in the surface, gap and blind hole of the component can be completely discharged, so that the cleaning agent can be completely immersed in each part of the workpiece, so that all parts of the workpiece can achieve the best cleaning effect. For workpieces with complex structures and deep blind holes, all air can be discharged through more than two vacuuming and exhausting processes. Therefore, in the vacuum state, the cleaning effect is better than that under normal pressure.
3. Reduce the boiling point so that hydrocarbon cleaning agent can also achieve gas phase cleaning. The use of halogenated hydrocarbon cleaning agent ultrasonic cleaning machine, the use of halogenated hydrocarbon cleaning agent low boiling point characteristics, in the last step of cleaning, the cleaning agent is heated to produce pure cleaning agent steam, with solution steam on the workpiece gas phase cleaning, so that the oil dissolved in the cleaning solution will not remain on the surface of the workpiece. Since the boiling point of the hydrocarbon cleaning agent is higher than the flash point, it is impossible to steam clean the workpiece under normal pressure. The vacuum cleaning dryer uses the principle that the boiling point of the liquid is reduced in the vacuum state. By vacuuming the sealed cleaning tank, the boiling point of the hydrocarbon solvent is greatly reduced. The hydrocarbon cleaning agent can be heated to about 80°C to make it Boiling to achieve gas phase cleaning.
4. The use of vacuum sudden boiling effect, improve the drying speed. Since the boiling point of the hydrocarbon cleaning agent is above 140°C, it generally takes about an hour to completely volatilize under normal temperature and pressure. Such a drying speed certainly can not meet the requirements of the rhythm of the process cleaning. The method of heating and drying is prone to fire danger, which is also one of the main reasons why hydrocarbon cleaning agents have not been widely used in China. Vacuum cleaning and drying machine is generally steam cleaning and vacuum drying in a tank, in the workpiece steam cleaning at the same time to raise the temperature of the workpiece, and then make the drying tank quickly into a higher vacuum state, the cleaning fluid on the surface of the workpiece will suddenly boil (vacuum sudden boiling effect) and quickly volatilize clean. In this way, the drying time of the workpiece can be reduced to less than 1 minute.
5. Vacuum distillation, so that the hydrocarbon cleaning agent regeneration reuse. The distillation regeneration of the cleaning agent is to use the boiling point difference between the cleaning agent and the dirt to heat the oil-soluble cleaning agent above the boiling point of the cleaning agent and control it below the boiling point of the oil, so that the cleaning agent vaporizes and then condenses it into a pure cleaning agent through a condensation device, while the oil and mechanical impurities with higher boiling point remain at the bottom of the distillation tank. Halogenated hydrocarbon cleaning agent due to low boiling point and non-flammable, distillation regeneration is relatively easy, so many halogenated hydrocarbon cleaning agents are accompanied by distillation regeneration device. The hydrocarbon cleaning agent due to the high boiling point and low flash point, at atmospheric pressure distillation regeneration is not possible. The distillation regeneration device of the vacuum cleaning dryer reduces the boiling point of the hydrocarbon cleaning agent to 80°C under high vacuum, so that the cleaning solution dissolved in the cleaning tank is continuously pumped into the distillation device, heated and evaporated in a vacuum, and then condensed into a cleaning solvent to return to the cleaning tank, so that the cleaning liquid is always kept clean. The oil remains at the bottom of the distillation unit and is discharged periodically.
6. Isolation of oxygen, so thathydrocarbon cleaning agentLoss of burning conditions. Most of the hydrocarbon cleaning agents have a flash point of about 50 ℃, which is a high flash point flammable liquid in the classification and marking of commonly used hazardous chemicals in China. Although the flash point is high, there is still a risk of burning at high temperatures or in the presence of combustion aids (such as paper and cotton wool). Therefore, the control of fire insurance has become a problem that must be solved in its promotion and use. Combustion requires three necessary conditions: combustibles, temperature and oxygen. As long as one is missing, combustion cannot occur. In the vacuum state, the oxygen content is very low, in the process of cleaning, drying and distillation regeneration, even ifhydrocarbon cleaning agentThe temperature reaches above the flash point, because there is no oxygen, losing a necessary condition for combustion,hydrocarbon cleaning agentIt will not burn, thus ensuring the safety of use.