Positive and negative pressure ultrasonic cleaning system and method for water conservancy project

Abstract

The positive and negative pressure ultrasonic cleaning system comprises a cleaning tank, an electric control device is arranged on the upper portion of the side wall of the cleaning tank, a plurality of ultrasonic transducers are evenly embedded in the bottom wall of the cleaning tank, the section of the top of the cleaning tank is round, and a frequency modulation ultrasonic generator is installed on the upper portion of the side wall of the cleaning tank. The electric control device is connected with the frequency modulation ultrasonic generator, and the frequency modulation ultrasonic generator is connected with the ultrasonic transducers through wires; the electric control device is connected with a display screen; the cleaning tank is connected with a negative pressure aeration box through a cleaning liquid exchange mechanism, a positive pressure generation structure is arranged at the top of the cleaning tank, and a negative pressure generation structure is arranged at the top of the negative pressure aeration box. The invention further discloses a corresponding cleaning method. The device has the advantage of cleaning after negative-pressure degassing, the cleaning efficiency and the cleaning effect are improved through positive-pressure cleaning, gas dissolved in cleaning liquid is rapidly removed through negative-pressure aeration, standing waves are eliminated through frequency conversion so as to enhance the cleaning uniformity, and the cleaning effect is improved. Standing waves are generated through fixed frequency, and the cleaning effect on the part, with most dirt, of a workpiece is enhanced through an antinode on the premise that power is not increased.

Description

Technical Field

[0001] The invention relates to cleaning and decontamination technology, in particular to ultrasonic cleaning technology for water conservancy equipment. Background Art

[0002] Water conservancy projects involve many devices and parts, some of which are exposed to humid, dusty and corrosive environments for a long time. In order to reduce corrosion, maintain lubrication, improve safety, clean appearance and prevent pollution, these parts need to be cleaned. For example, the steel wire rope of the sluice, some valves, the blades and sealing parts of the turbine, water quality monitoring equipment and other parts, regular or irregular cleaning of these parts can achieve the above purposes, extend their service life and ensure their safe operation.

[0003] In the related prior art, commonly used parts cleaning methods include (but are not limited to): 1. Chemical cleaning: Use specific chemical cleaning agents to clean parts. The disadvantage is that the wastewater produced is somewhat polluting.

[0004] 2. Mechanical cleaning: Use brushes, steel wool, sandpaper and other tools to physically wipe to remove dirt and rust. The disadvantage is that it consumes a lot of manpower and may cause physical damage to the surface of parts.

[0005] 3. Ultrasonic cleaning.

[0006] Ultrasonic cleaning is a highly efficient cleaning technology that uses the cavitation effect produced by ultrasound in liquid to remove dirt from the surface of objects. Compared with traditional cleaning methods, ultrasonic cleaning can penetrate into tiny gaps and hard-to-reach areas on the surface of objects, with good cleaning effects and high cleaning efficiency. The surface cleaning effect of parts is more uniform, and the cleaning process will not damage the parts. It is safe and environmentally friendly. The cleaning process does not require flammable and explosive chemical solvents, and does not produce harmful wastewater or exhaust gas with chemical pollution. The energy required for cleaning is relatively small, saving water and energy. The entire cleaning process is more energy-saving and environmentally friendly than other cleaning methods (except manual physical cleaning), and has therefore been increasingly widely used.

[0007] The working principle of ultrasonic cleaning is to use the high-frequency sound waves generated by the ultrasonic vibrator to form tiny bubbles through the conduction of the cleaning liquid, which quickly expand and burst in the liquid, generating high-temperature and high-pressure shock waves (i.e. cavitation effect), thereby effectively stripping the dirt from the surface of the parts. At the same time, the vibration of the ultrasonic wave can also help the cleaning liquid penetrate into the tiny gaps of the parts (such as wire ropes) to achieve a comprehensive cleaning effect.

[0008] The gas dissolved in the liquid has an inhibitory effect on the cavitation effect, specifically: ① Sound wave attenuation. The gas dissolved in the liquid absorbs ultrasonic energy and reduces the intensity of the cavitation effect. Specifically, when cavitation bubbles burst in the liquid (cleaning liquid), they will produce strong shock waves and high-speed microjets, which is the main mechanism of ultrasonic cleaning. If there is too much gas dissolved in the liquid, the impact force generated when the bubbles burst will be weakened, reducing the cleaning effect. ② The formation and growth of bubbles. The gas dissolved in the liquid will increase the saturated vapor pressure of the liquid, making it more difficult for cavitation bubbles to form and grow.

[0009] ③ Stability of cavitation nuclei. The gas dissolved in the liquid can serve as the source of cavitation nuclei (i.e. the initial core of the bubbles). If there is too much gas dissolved in the liquid, these bubbles may be too stable and difficult to burst, thus weakening the cleaning effect.

[0010] Based on the above reasons, it is generally believed in the art that negative pressure degassing technology is beneficial to ultrasonic cleaning, and therefore negative pressure is often created in the cleaning tank to degas the cleaning liquid to solve the problem that the gas dissolved in the liquid has an inhibitory effect on the cavitation effect.

[0011] Through in-depth research, the applicant found that in addition to negative pressure conditions being beneficial to ultrasonic cleaning, positive pressure conditions are also beneficial to ultrasonic cleaning. The principle that positive pressure conditions are beneficial to ultrasonic cleaning is: ① Enhance the cavitation effect. Under moderate positive pressure, the bubbles in the liquid will be compressed, which increases the rupture strength of the bubbles under the action of ultrasound, thereby enhancing the shock wave and high-speed micro-jet intensity when the bubbles rupture, and improving the cleaning efficiency and cleaning effect.

[0012] ② Enhance the cleaning depth. The positive pressure environment can increase the density of the cleaning fluid and the speed of sound therein to a certain extent, enhance the propagation efficiency of ultrasonic waves in the cleaning fluid, and facilitate the ultrasonic waves to penetrate deeper into the tiny gaps of the parts being cleaned, thereby improving the cleaning depth and cleaning effect.

[0013] ③ Increased gas solubility. Under positive pressure, the solubility of gas in liquid increases, which reduces the number of free bubbles in the liquid, thereby reducing the interference caused by bubbles during the cleaning process, improving the propagation efficiency of ultrasonic waves, and reducing the propagation loss of ultrasonic waves.

[0014] One of the innovative ideas of the present invention is to comprehensively utilize negative pressure environment and positive pressure environment, and utilize their respective advantages to improve cavitation effect, cleaning efficiency and cleaning effect. In the prior art, negative pressure environment and positive pressure environment cannot coexist, so there is only negative pressure degassing ultrasonic cleaning technology, no positive pressure ultrasonic cleaning technology, and even less ultrasonic cleaning technology that comprehensively utilizes negative pressure environment and positive pressure environment.

[0015] The second innovative idea of ​​the present invention is to use the antinode of the standing wave to enhance the cleaning effect of local stubborn dirt. The applicant has found that when the ultrasonic vibrator is installed at the bottom of the cleaning tank (usually installed at the bottom of the tank), a standing wave will be formed in the cleaning liquid, and the antinode and the node will appear alternately in the vertical direction. The antinode area vibrates strongly (the position with the largest amplitude in the standing wave), which helps to enhance the cleaning effect. The node area vibrates weakly (the position with the smallest amplitude in the standing wave), and the cleaning effect is relatively poor.

[0016] On the one hand, the applicant uses frequency conversion technology to change the position of the antinodes and nodes to make the cleaning effect more uniform. On the other hand, the applicant uses frequency conversion technology to control the antinode position of the standing wave at the position of stubborn dirt on the parts of the water conservancy project, so that the energy is more concentrated on the stubborn dirt position (antinode position) without increasing the power, thereby utilizing the antinode to improve the cleaning effect of stubborn dirt.

[0017] The third innovative idea of ​​the present invention is aeration and degassing technology. In the existing water treatment technology, aeration is an important means to increase dissolved oxygen in water, not a degassing technical means. The present invention uses aeration technology as a technical means to enhance the degassing effect. Summary of the invention

[0018] The purpose of the present invention is to provide a positive and negative pressure ultrasonic cleaning system for water conservancy projects, which comprehensively utilizes positive and negative pressure technical means, not only to eliminate the inhibitory effect of dissolved gas in the liquid on cavitation effect through negative pressure degassing, but also to improve cleaning efficiency and cleaning effect through positive pressure cleaning.

[0019] To achieve the above-mentioned purpose, the positive and negative pressure ultrasonic cleaning system for water conservancy projects of the present invention comprises a cleaning tank, an electric control device is provided on the upper part of the side wall of the cleaning tank, and a plurality of ultrasonic transducers are evenly embedded on the bottom wall of the cleaning tank, and the characteristics are: the top cross section of the cleaning tank is circular, a frequency-modulated ultrasonic generator is installed on the upper part of the side wall of the cleaning tank, the electric control device is connected to the frequency-modulated ultrasonic generator, and the frequency-modulated ultrasonic generator is connected to each ultrasonic transducer through a wire; the electric control device is connected to a display screen; The cleaning tank is connected to a negative pressure aeration tank through a cleaning liquid exchange mechanism. A positive pressure generating structure is provided on the top of the cleaning tank, and a negative pressure generating structure is provided on the top of the negative pressure aeration tank. The cleaning liquid exchange mechanism is used for two functions, AB. The function of A is to send the cleaning liquid that has been aerated by negative pressure into the cleaning tank to perform ultrasonic cleaning on the parts of the water conservancy project; The function of B is to send the cleaning liquid that has been cleaned under positive pressure and dissolved with a certain amount of gas into the negative pressure aeration box for negative pressure aeration and degassing.

[0020] The cleaning liquid exchange mechanism includes a connecting pipe, a second filter cover is provided at the bottom of one side of the cleaning tank, and a liquid extraction cavity is formed between the second filter cover and the inner wall of the cleaning tank. One end of the connecting pipe is connected to the liquid extraction cavity at the bottom of the cleaning tank and the other end is connected to the negative pressure aeration tank; A filter, a two-position three-way solenoid valve at the inlet end, a liquid pump and a two-position three-way solenoid valve at the outlet end are sequentially arranged on the connecting pipe from the negative pressure aeration box to the cleaning tank; the two-position three-way solenoid valve at the inlet end and the two-position three-way solenoid valve at the outlet end are both connected to the electric control device; The two-position three-way solenoid valve at the inlet end is connected to the cleaning tank through the first bypass pipe; the inlet of the liquid pump is selectively connected to the negative pressure aeration tank or the cleaning tank through the two-position three-way solenoid valve at the inlet end; The two-position three-way solenoid valve at the outlet is connected to the negative pressure aeration tank through the second bypass pipe, and the outlet of the liquid pump is selectively connected to the cleaning tank or the negative pressure aeration tank through the two-position three-way solenoid valve at the outlet; A first ventilation pipe is connected to the top of the negative pressure aeration box, and a first ventilation solenoid valve is provided on the first ventilation pipe; A second ventilation pipe is connected to the top of the cleaning tank, and a second ventilation solenoid valve is arranged on the second ventilation pipe; the first ventilation solenoid valve and the second ventilation solenoid valve are both connected to the electric control device.

[0021] The top section of the negative pressure aeration box is circular and has external threads; The negative pressure generating mechanism includes a negative pressure top cover threadedly connected to the top of the negative pressure aeration box. The negative pressure top cover is provided with a vacuum pump and an electronic negative pressure gauge. The electronic negative pressure gauge is used to monitor the pressure in the negative pressure aeration box. The vacuum pump is connected to an exhaust pipe. The exhaust pipe is provided with an exhaust solenoid valve. The exhaust pipe passes through the negative pressure top cover and extends into the negative pressure aeration box.

[0022] A first filter cover is provided at the bottom of the negative pressure aeration box, and a micro-circulation pump is provided in the first filter cover. The inlet of the micro-circulation pump is communicated with the bottom of the negative pressure aeration box, and the outlet of the micro-circulation pump is connected with a hard vertical pipe. The vertical pipe is connected with multiple layers of horizontally arranged aeration disks from top to bottom, and the diameter of each layer of aeration disk increases step by step from top to bottom; the top end of the vertical pipe is opened at the uppermost aeration disk; the vacuum pump, electronic negative pressure gauge, exhaust solenoid valve and micro-circulation pump are all connected with the electronic control device.

[0023] The top cross-section of the cleaning tank is circular and has an external thread; the positive pressure generating structure includes a positive pressure top cover threadedly connected to the top of the cleaning tank, on which an air pump and an electronic pressure gauge are provided, and the electronic pressure gauge is used to monitor the pressure in the cleaning tank; the air pump is connected to an air supply pipe, on which an air supply solenoid valve is provided, and the air supply pipe passes through the positive pressure top cover and extends into the cleaning tank; the air pump, the electronic pressure gauge and the air supply solenoid valve are all connected to the electronic control device.

[0024] The side wall of the cleaning tank is provided with a vertically arranged observation window, and a number of vibration sensors are installed on the observation window from top to bottom at intervals. Each vibration sensor is used to sense the vibration intensity at its position so as to locate the antinode of the standing wave at the position with the strongest vibration; each vibration sensor is connected to the electronic control device.

[0025] The present invention also discloses a cleaning method using the positive and negative pressure ultrasonic cleaning system for water conservancy projects, which is carried out according to the following steps: The first step is the preparation step; the parts of the water conservancy project to be cleaned are called workpieces; collect all the workpieces of the same model to be cleaned, put the first workpiece into the cleaning tank, inject cleaning liquid into the negative pressure aeration tank, cover the positive pressure top cover and the negative pressure top cover, and keep all valves in a closed state; The second step is the negative pressure aeration degassing step; Start the micro-circulation pump to pump the cleaning liquid at the bottom of the negative pressure aeration box to the top aeration plate. The cleaning liquid is spread out on the top aeration plate and falls from the edge of the top aeration plate to the adjacent aeration plate on the lower layer and spread out. The cleaning liquid is spread out on each layer of aeration plates and falls down layer by layer until it falls back into the cleaning liquid from the bottom aeration plate. Start the vacuum pump to evacuate the negative pressure aeration box, thereby reducing the pressure in the negative pressure aeration box; when the electronic pressure gauge detects that the pressure in the negative pressure aeration box is lower than or equal to the predetermined target negative pressure, turn off the vacuum pump and the exhaust solenoid valve; Each layer of aeration disc provides space for the cleaning liquid to be spread out in multiple layers. The cleaning liquid falls layer by layer to form a multi-layer liquid curtain, thereby increasing the contact area between the cleaning liquid and the gas in the negative pressure aeration box, and combining the negative pressure environment to improve the degassing efficiency and degassing effect; The third step is to send the degassed cleaning solution into the cleaning tank; The fourth step is a positive pressure cleaning step; The fifth step is a cyclic cleaning step, replacing the next workpiece of the same type, and repeating the second to fourth steps until the cleaning of all workpieces of the same type is completed.

[0026] The third step is specifically: Turn off the vacuum pump, open the first ventilation solenoid valve and the second ventilation solenoid valve, so that the inlet of the liquid pump is connected to the negative pressure aeration tank through the two-position three-way solenoid valve at the inlet end, and the outlet of the liquid pump is connected to the cleaning tank through the two-position three-way solenoid valve at the outlet end; Turn on the liquid pump to send the cleaning liquid in the negative pressure aeration tank into the cleaning tank; the staff sets the corresponding cleaning liquid level for the same type of workpiece; Observe the liquid level in the cleaning tank through the observation window, and when the liquid level reaches the cleaning liquid level, close the liquid pump, the first ventilation solenoid valve and the second ventilation solenoid valve.

[0027] The fourth step is specifically: turning on the air pump and the air supply solenoid valve to increase the air pressure in the cleaning tank; when the pressure in the cleaning tank is higher than or equal to the predetermined target positive pressure, turning off the air pump and the air supply solenoid valve; The electronic control device controls the frequency-modulated ultrasonic generator to emit an electrical signal with a certain frequency and transmits it to each ultrasonic transducer. Each ultrasonic transducer generates ultrasonic waves of the same frequency. For specific types of workpieces, the staff sets the central frequency and cleaning time for cleaning. When the first workpiece of the same model is being cleaned, the staff controls the ultrasonic frequency to the central frequency for cleaning through the electronic control device and the frequency-modulated ultrasonic generator, and a standing wave is formed in the cleaning liquid. Then the readings of each vibration sensor are observed on the display screen to determine the location of each antinode of the standing wave, and a marker is used to draw an antinode marking line at the corresponding position of the observation window, which provides a basis for subsequent workpieces of the same model to use the antinode to clean stubborn dirt. After the antinode marking line is drawn or when the subsequent workpiece of the same model begins to be cleaned, the frequency of the ultrasonic wave is controlled by the electronic control device to oscillate up and down around the center frequency to weaken the standing wave phenomenon and improve the uniformity of cleaning; When the positive pressure cleaning time reaches the cleaning time, turn off the frequency-modulated ultrasonic generator and each ultrasonic transducer to complete the fourth step.

[0028] The fifth step is specifically: open the first ventilation solenoid valve and the second ventilation solenoid valve, so that the inlet of the liquid pump is selectively connected to the cleaning tank through the two-position three-way solenoid valve at the inlet end, and the outlet of the liquid pump is selectively connected to the negative pressure aeration tank through the two-position three-way solenoid valve at the outlet end; turn on the liquid pump to send the cleaning liquid in the negative pressure aeration tank into the cleaning tank, and then close the first ventilation solenoid valve; For the negative pressure aeration box, the second step is performed, and the positive pressure top cover is opened at the same time, the cleaned workpiece is taken out, and the next workpiece of the same model to be cleaned is placed. The staff visually judges the part with the most dirt on the workpiece, and when placing the workpiece into the cleaning tank, the part with the most dirt on the workpiece is aligned with a drawn antinode marking line; then the positive pressure top cover is closed; After the second step is completed for the negative pressure aeration box, the third and fourth steps are re-executed; During the execution of the fourth step, when the positive pressure cleaning time reaches the cleaning time, the staff observes the most contaminated part of the workpiece through the observation window; If the cleaning effect of the part with the most dirt on the workpiece meets the requirements, the fifth step is executed again; If the staff determines that the part of the workpiece with the most dirt needs further cleaning, the frequency of the ultrasonic wave is controlled by the electronic control device to be stable at the set cleaning center frequency for fixed-frequency cleaning. At this time, a standing wave is formed in the cleaning liquid and the part of the workpiece with the most dirt is located at the anti-trend position, so that the energy of ultrasonic cleaning and the cavitation effect are more concentrated on the part of the workpiece with the most dirt, thereby improving the cleaning effect of the part of the workpiece with the most dirt. After the fixed-frequency cleaning is performed for three to five minutes, the cleaning work on the workpiece is ended and the fifth step is performed again.

[0029] The present invention has the following advantages: By utilizing the structure of the present invention, the cleaning liquid can be degassed by negative pressure aeration in a negative pressure aeration box, and the degassed cleaning liquid is sent to a cleaning tank for positive pressure ultrasonic cleaning. In a positive pressure environment, it is not easy for gas to dissolve into the cleaning liquid, and ultrasonic cleaning itself is highly efficient, so the amount of gas in the cleaning liquid can be kept low during the cleaning process, avoiding excessive gas dissolved in the cleaning liquid and inhibiting the cavitation effect in ultrasonic cleaning. In the cleaning tank, a positive pressure generating structure is used to apply a certain positive pressure (usually less than 2 times the atmospheric pressure, such as maintaining 1.4 times the atmospheric pressure in the cleaning tank) to the cleaning liquid and the parts of the water conservancy project to be cleaned for positive pressure cleaning. The positive pressure environment enhances the bubble rupture strength (bubbles need to resist greater pressure when they rupture), enhances the cavitation effect, reduces the propagation interference of ultrasonic waves in the cleaning liquid, and improves the propagation efficiency of the cleaning liquid, thereby improving the efficiency and effect of ultrasonic cleaning.

[0030] Since a certain amount of gas will be dissolved in the cleaning fluid during the cleaning process of parts in a positive pressure environment, if the cleaning fluid is not degassed again, the gas in it will gradually increase as the cleaning fluid participates in the cleaning operation again and again. Therefore, the cleaning fluid exchange mechanism can alternately play the two roles of AB to continuously maintain the cleaning fluid in a state with a small amount of dissolved gas, avoiding excessive dissolved gas from inhibiting the cavitation effect.

[0031] Aeration technology is used as a degassing technology. Aeration increases the contact area between the cleaning liquid and the air in a negative pressure environment, making the gas in the cleaning liquid easier to evaporate under the same negative pressure conditions, thereby achieving the purpose of promoting degassing.

[0032] The cleaning liquid exchange mechanism has a simple structure, and a liquid pump is used to send the cleaning liquid from the cleaning tank to the negative pressure aeration tank, or from the negative pressure aeration tank to the cleaning liquid. The second filter cover and the liquid extraction cavity can prevent impurities generated during cleaning from clogging the connecting pipe.

[0033] The vacuum pump and the exhaust solenoid valve are used to form and maintain a negative pressure state in the negative pressure aeration box; during degassing, the micro-circulation pump continuously pumps the cleaning liquid at the bottom of the negative pressure aeration box to the top aeration plate, and then the cleaning liquid falls from the top aeration plate to the lower aeration plate layer by layer until it falls from the bottom aeration plate back to the cleaning liquid in the negative pressure aeration box; the above process greatly increases the contact area between the cleaning liquid and the low-pressure air, improves the effect of negative pressure degassing, and allows the gas in the cleaning liquid to be separated from the cleaning liquid faster and more effectively. The positive pressure generating structure can easily form and maintain positive pressure in the cleaning tank.

[0034] Since cleaning is performed in a positive pressure environment using a degassed cleaning fluid (rather than directly performing negative pressure cleaning in a negative pressure environment, which fails to utilize the mechanism of positive pressure cleaning to improve cleaning efficiency and effectiveness), the present invention not only has the advantages of negative pressure degassing cleaning, but also utilizes positive pressure cleaning for the first time to further increase the cleaning depth of the workpiece, reduce the number of free bubbles in the cleaning fluid, and enhance the cavitation effect, thereby further improving the efficiency and effectiveness of ultrasonic cleaning.

[0035] In the present invention, the frequency of the ultrasonic wave oscillates up and down around the central frequency, so that the standing wave cannot be stably formed, and a uniform cavitation effect is formed in all parts of the cleaning liquid, thereby improving the uniformity of cleaning.

[0036] The present invention comprehensively utilizes variable frequency cleaning to eliminate standing waves and improve the uniformity of cleaning at all locations of the workpiece. At the same time, the present invention also comprehensively utilizes the antinodes of standing waves to concentrate more cleaning capacity on the most contaminated locations of the workpiece, generating a stronger cavitation effect there while keeping the overall power constant, thereby improving the cleaning efficiency (speed) and cleaning effect (contaminant removal rate) at the most contaminated locations of the workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a structural schematic diagram of the present invention.

[0038] Figure 2 It is a schematic diagram of the electric control structure of the present invention. DETAILED DESCRIPTION

[0039] like Figure 1 and Figure 2 As shown, the positive and negative pressure ultrasonic cleaning system for water conservancy projects of the present invention comprises a cleaning tank 1, an electric control device 2 is provided on the upper part of the side wall of the cleaning tank 1, a plurality of ultrasonic transducers 3 are evenly embedded on the bottom wall of the cleaning tank 1, the top cross-section of the cleaning tank 1 is circular, a frequency-modulated ultrasonic generator 4 is installed on the upper part of the side wall of the cleaning tank 1, the electric control device 2 is connected to the frequency-modulated ultrasonic generator 4, and the frequency-modulated ultrasonic generator 4 is connected to each ultrasonic transducer 3 through a wire; the electric control device 2 adopts a single-chip microcomputer (including a PLC) or an industrial control computer, and the electric control device 2 is connected to a display screen 5; The cleaning tank 1 is connected to the negative pressure aeration box 6 through the cleaning liquid exchange mechanism. A positive pressure generating structure is provided on the top of the cleaning tank 1, and a negative pressure generating structure is provided on the top of the negative pressure aeration box 6. The cleaning liquid exchange mechanism is used for two functions AB. The function of A is to send the cleaning liquid that has been aerated by negative pressure into the cleaning tank 1 to perform ultrasonic cleaning on the parts of the water conservancy project; The function of B is to send the cleaning liquid that has been cleaned under positive pressure and dissolved with a certain amount of gas into the negative pressure aeration box 6 for negative pressure aeration and degassing.

[0040] By utilizing the structure of the present invention, the cleaning liquid can be degassed by negative pressure aeration in the negative pressure aeration box 6, and the degassed cleaning liquid is sent to the cleaning tank 1 for positive pressure ultrasonic cleaning. In a positive pressure environment, it is not easy for the gas to dissolve into the cleaning liquid, and the ultrasonic cleaning itself is highly efficient, so the amount of gas in the cleaning liquid can be kept low during the cleaning process, avoiding excessive gas dissolved in the cleaning liquid and inhibiting the cavitation effect in ultrasonic cleaning. In the cleaning tank 1, a positive pressure generating structure is used to apply a certain positive pressure (usually less than 2 times the atmospheric pressure, such as maintaining 1.4 times the atmospheric pressure in the cleaning tank 1) to the cleaning liquid and the parts of the water conservancy project to be cleaned for positive pressure cleaning. The positive pressure environment enhances the bubble rupture strength (a greater pressure is required when the bubble ruptures), enhances the cavitation effect, reduces the propagation interference of ultrasonic waves in the cleaning liquid, and improves the propagation efficiency of the cleaning liquid, thereby improving the efficiency and effect of ultrasonic cleaning.

[0041] Since a certain amount of gas will be dissolved in the cleaning fluid during the cleaning process of parts in a positive pressure environment, if the cleaning fluid is not degassed again, the gas in it will gradually increase as the cleaning fluid participates in the cleaning operation again and again. Therefore, the cleaning fluid exchange mechanism can alternately play the two roles of AB to continuously maintain the cleaning fluid in a state with a small amount of dissolved gas, avoiding excessive dissolved gas from inhibiting the cavitation effect.

[0042] The cleaning liquid exchange mechanism includes a connecting pipe 7, a second filter cover 8 is provided at the bottom of one side of the cleaning tank 1, and a liquid extraction cavity is formed between the second filter cover 8 and the inner wall of the cleaning tank 1; One end of the connecting pipe 7 is connected to the liquid extraction cavity at the bottom of the cleaning tank 1 and the other end is connected to the negative pressure aeration tank 6; A filter 9, a two-position three-way solenoid valve 10 at the inlet end, a liquid pump 11 and a two-position three-way solenoid valve 12 at the outlet end are sequentially arranged on the connecting pipe 7 from the negative pressure aeration tank 6 to the cleaning tank 1; the two-position three-way solenoid valve 10 at the inlet end and the two-position three-way solenoid valve 12 at the outlet end are both connected to the electronic control device 2; the filter 9 is used to remove most of the impurities that may be present.

[0043] The two-position three-way solenoid valve 10 at the inlet end is connected to the cleaning tank 1 through the first bypass pipe 13; the inlet of the liquid pump 11 is selectively connected to the negative pressure aeration tank 6 or the cleaning tank 1 through the two-position three-way solenoid valve 10 at the inlet end; The two-position three-way solenoid valve 12 at the outlet end is connected to the negative pressure aeration tank 6 through the second bypass pipe 14, and the outlet of the liquid pump 11 is selectively connected to the cleaning tank 1 or the negative pressure aeration tank 6 through the two-position three-way solenoid valve 12 at the outlet end; A first ventilation pipe 15 is connected to the top of the negative pressure aeration box 6, and a first ventilation solenoid valve 16 is provided on the first ventilation pipe 15; A second ventilation pipe 17 is connected to the top of the cleaning tank 1, and a second ventilation solenoid valve 18 is provided on the second ventilation pipe 17; the first ventilation solenoid valve 16 and the second ventilation solenoid valve 18 are both connected to the electronic control device 2. The heights of the first ventilation pipe 15 and the second ventilation pipe 17 are both higher than the liquid level of the cleaning liquid.

[0044] The cleaning liquid exchange mechanism has a simple structure, and a liquid pump 11 is used to deliver the cleaning liquid from the cleaning tank 1 to the negative pressure aeration tank 6, or from the negative pressure aeration tank 6 to the cleaning liquid. The second filter cover 8 and the liquid extraction cavity can prevent impurities generated during cleaning from clogging the connecting pipe 7.

[0045] The top cross-section of the negative pressure aeration box 6 is circular and has external threads; the negative pressure generating mechanism includes a negative pressure top cover 19 threadedly connected to the top of the negative pressure aeration box 6, and the negative pressure top cover 19 is provided with a vacuum pump 20 and an electronic negative pressure gauge 21, and the electronic negative pressure gauge 21 is used to monitor the pressure in the negative pressure aeration box 6, and the vacuum pump 20 is connected to a suction pipe 22, and the suction pipe 22 is provided with a suction solenoid valve 23, and the suction pipe 22 passes through the negative pressure top cover 19 and extends into the negative pressure aeration box 6. A sealing gasket is preferably pressed between the negative pressure top cover 19 and the negative pressure aeration box 6, and a sealing gasket is preferably pressed between the positive pressure top cover and the cleaning tank 1 (the sealing gasket is a horizontal annular sealing ring at the lower surface of the top cover).

[0046] A first filter cover 24 is provided at the bottom of the negative pressure aeration box 6, and a micro-circulation pump 25 is provided in the first filter cover 24. The inlet of the micro-circulation pump 25 is communicated with the bottom of the negative pressure aeration box 6, and the outlet of the micro-circulation pump 25 is connected to a hard vertical pipe 26. The vertical pipe 26 is connected with multiple layers of horizontally arranged aeration discs 27 at intervals from top to bottom, and the diameter of each layer of aeration disc 27 increases from top to bottom (that is, in the two adjacent layers of aeration discs 27, the diameter of the aeration disc 27 of the lower layer is larger than the diameter of the aeration disc 27 of the upper layer); the top end of the vertical pipe 26 opens at the topmost aeration disc 27; The vacuum pump 20 , the electronic negative pressure gauge 21 , the air extraction solenoid valve 23 and the micro circulation pump 25 are all connected to the electronic control device 2 .

[0047] The vacuum pump 20 and the exhaust solenoid valve 23 are used to form and maintain a negative pressure state in the negative pressure aeration box 6; during degassing, the micro-circulation pump 25 continuously pumps the cleaning liquid at the bottom of the negative pressure aeration box 6 to the top aeration plate 27, and then the cleaning liquid falls layer by layer from the top aeration plate 27 to the lower aeration plate 27 until it falls back into the cleaning liquid in the negative pressure aeration box 6 from the bottom aeration plate 27; the above process greatly increases the contact area between the cleaning liquid and the low-pressure air, improves the effect of negative pressure degassing, and allows the gas in the cleaning liquid to separate from the cleaning liquid faster and more effectively.

[0048] The top section of the cleaning tank 1 is circular and has an external thread; the positive pressure generating structure includes a positive pressure cover 28 threadedly connected to the top of the cleaning tank 1, and an air pump 29 and an electronic pressure gauge 30 are provided on the positive pressure cover 28, and the electronic pressure gauge 30 is used to monitor the pressure in the cleaning tank 1; the air pump 29 is connected to an air supply pipe 31, and an air supply solenoid valve 32 is provided on the air supply pipe 31, and the air supply pipe 31 passes through the positive pressure cover 28 and extends into the cleaning tank 1; the air pump 29, the electronic pressure gauge 30 and the air supply solenoid valve 32 are all connected to the electronic control device 2. The positive pressure generating structure can easily form positive pressure in the cleaning tank 1 and maintain the positive pressure state.

[0049] The side wall of the cleaning tank 1 is provided with a vertically arranged transparent observation window 33, and a plurality of vibration sensors 34 are installed at intervals from top to bottom on the observation window 33, and each vibration sensor 34 is used to sense the vibration intensity at its position so as to locate the antinode of the standing wave at the position where the vibration is the strongest; each vibration sensor 34 is connected to the electric control device 2. Each vibration sensor 34 and the connection line between each ultrasonic transducer 3 and the electric control device 2 are preferably buried in the side wall of the cleaning tank 1.

[0050] Figure 1 The top two vibration sensors 34 exceed the current liquid level 35. This is because different components require different liquid levels. The setting of the vibration sensor 34 needs to meet the need to locate the wave nose position of all components at the predetermined cleaning center frequency as much as possible (that is, the cleaning liquid level required by the current workpiece is not the highest liquid level required by all workpieces).

[0051] In the present invention, the connection lines of the air pump 29, the vacuum pump 20, the electronic negative pressure gauge 21 and the electronic pressure gauge 30 are preferably provided with connectors, and the lines at both ends of the connectors are respectively connected to the equipment (air pump 29, vacuum pump 20, electronic negative pressure gauge 21 or electronic pressure gauge 30) and the electronic control device 2. After the negative pressure top cover 19 and the positive pressure top cover 28 are connected to the corresponding negative pressure aeration box 6 and the cleaning tank 1, the corresponding connectors are connected to connect the air pump 29, the vacuum pump 20, the electronic negative pressure gauge 21 and the electronic pressure gauge 30 to the electronic control device 2 through the connection lines with the connectors. Of course, the connectors can also be eliminated, and each connection line can be directly set to have a sufficient redundant length, so that when the negative pressure top cover 19 and the positive pressure top cover 28 are rotated to install or remove, the connection lines will not hinder the installation and removal of the negative pressure top cover 19 and the positive pressure top cover 28.

[0052] The present invention also discloses a cleaning method using the positive and negative pressure ultrasonic cleaning system for water conservancy projects, which is carried out according to the following steps: The first step is the preparation step; the parts of the water conservancy project to be cleaned are called workpieces; all workpieces of the same type to be cleaned are collected, the first workpiece is placed in the cleaning tank 1, the cleaning liquid is injected into the negative pressure aeration tank 6, the positive pressure top cover 28 and the negative pressure top cover 19 are covered, and all valves (solenoid valves) are kept in a closed state; The second step is the negative pressure aeration degassing step; Start the micro-circulation pump 25 to pump the cleaning liquid pump 11 at the bottom of the negative pressure aeration box 6 to the uppermost aeration plate 27. The cleaning liquid is spread out on the uppermost aeration plate 27 and falls from the edge of the uppermost aeration plate 27 to the lower adjacent aeration plate 27 and spread out. The cleaning liquid is spread out layer by layer on the aeration plates 27 and falls layer by layer until it falls from the lowermost aeration plate 27 back into the cleaning liquid below. Figure 1 It is a structural diagram. In fact, the negative pressure aeration box should be larger than the cleaning tank so as to provide sufficient degassed cleaning fluid for the cleaning tank, and all or part of the cleaning fluid can be replaced after cleaning several workpieces.

[0053] The vacuum pump 20 is started to evacuate the negative pressure aeration box 6, thereby reducing the pressure in the negative pressure aeration box 6; when the electronic pressure gauge 30 detects that the pressure in the negative pressure aeration box 6 is lower than or equal to the predetermined target negative pressure (such as 100 mbar, i.e., about 0.1 atmosphere), the vacuum pump 20 and the exhaust solenoid valve 23 are turned off; Each layer of aeration disc 27 provides a space for the cleaning liquid to be spread out in multiple layers, and the cleaning liquid falls layer by layer to form a multi-layer liquid curtain, thereby greatly increasing the contact area between the cleaning liquid and the gas in the negative pressure aeration box 6, and combining with the negative pressure environment to improve the degassing efficiency (referring to a faster degassing speed) and degassing effect (referring to more gas being finally removed by the cleaning liquid); The third step is to send the degassed cleaning solution into the cleaning tank 1; The fourth step is a positive pressure cleaning step; The fifth step is a cyclic cleaning step, replacing the next workpiece of the same type, and repeating the second to fourth steps until the cleaning of all workpieces of the same type is completed.

[0054] The third step is specifically: Turn off the vacuum pump 20, open the first ventilation solenoid valve 16 and the second ventilation solenoid valve 18, so that the inlet of the liquid pump 11 is selectively connected to the negative pressure aeration tank 6 through the two-position three-way solenoid valve 10 at the inlet end, and the outlet of the liquid pump 11 is selectively connected to the cleaning tank 1 through the two-position three-way solenoid valve 12 at the outlet end; Turn on the liquid pump 11 to send the cleaning liquid in the negative pressure aeration tank 6 into the cleaning tank 1; the staff sets the corresponding cleaning liquid level for the same type of workpiece (the liquid level required for cleaning the workpiece of this type is usually located at one-half to four-fifths of the cleaning tank 1 from bottom to top, including both end values); The liquid level in the cleaning tank 1 is observed through the observation window 33. When the liquid level reaches the cleaning liquid level, the liquid pump 11, the first ventilation solenoid valve 16 and the second ventilation solenoid valve 18 are closed.

[0055] The fourth step is specifically: turning on the air pump 29 and the air supply solenoid valve 32 to increase the air pressure in the cleaning tank 1; when the pressure in the cleaning tank 1 is higher than or equal to a predetermined target positive pressure (such as 1400 mbar or 1600 mbar, i.e., about 1.4 standard atmospheres or about 1.6 standard atmospheres; this pressure is usually not preferably higher than 2 standard atmospheres), turning off the air pump 29 and the air supply solenoid valve 32; The electric control device 2 controls the frequency modulated ultrasonic generator 4 to emit an electrical signal with a certain frequency and transmits it to each ultrasonic transducer 3, and each ultrasonic transducer 3 generates ultrasonic waves with the same frequency; for a specific type of workpiece, the staff sets the cleaning center frequency and cleaning time (the appropriate cleaning center frequency and cleaning time can be set for a specific type of workpiece through trial operation, such as 45KHz and 10 minutes), When the first workpiece of the same model begins to be cleaned, the staff controls the ultrasonic frequency to the central frequency for cleaning through the electronic control device and the frequency-modulated ultrasonic generator, and a standing wave is formed in the cleaning liquid at this time; then the display screen 5 is used to observe the readings of each vibration sensor 34, and the position of each antinode of the standing wave is determined (the position with the strongest vibration is the antinode position, and the position with the weakest vibration is the node position), and a marking pen (such as a marker or a fluorescent pen) is used to draw an antinode marking line at the corresponding position of the observation window 33, so as to provide a basis for subsequent workpieces of the same model to use the antinode to clean stubborn dirt; Since different types of workpieces have different cleaning liquid levels and cleaning center frequencies, resulting in different antinode positions, different antinode positions need to be marked for different types of workpieces.

[0056] After the anti-node marking line is drawn (this is for the first workpiece of the same model to be cleaned) or when the subsequent workpieces of the same model begin to be cleaned, the frequency of the ultrasonic wave is controlled by the electronic control device 2 (the direct control object of the electronic control device 2 is the frequency of the frequency-modulated ultrasonic generator 4 and the frequency of the electrical signal it emits) to oscillate up and down around the center frequency for cleaning to weaken the standing wave phenomenon and improve the uniformity of cleaning; when the ultrasonic frequency oscillates up and down around the center frequency, the highest frequency is less than or equal to 2.5 times the center frequency for cleaning, and the lowest frequency is greater than or equal to 0.35 times the center frequency for cleaning. The ultrasonic frequency range, such as 0.5 times the center frequency for cleaning to twice the center frequency for cleaning, is specifically set by the staff.

[0057] When the positive pressure cleaning time reaches the cleaning time, the frequency modulated ultrasonic generator 4 and each ultrasonic transducer 3 are turned off to complete the fourth step.

[0058] The fifth step is specifically: open the first ventilation solenoid valve 16 and the second ventilation solenoid valve 18, so that the inlet of the liquid pump 11 is selectively connected to the cleaning tank 1 through the two-position three-way solenoid valve 10 at the inlet end, and the outlet of the liquid pump 11 is selectively connected to the negative pressure aeration tank 6 through the two-position three-way solenoid valve 12 at the outlet end; open the liquid pump 11, and send the cleaning liquid in the negative pressure aeration tank 6 into the cleaning tank 1 (it is not necessary to send 100% into the cleaning tank 1, and a small amount of cleaning liquid must be left in the cleaning liquid), and then close the first ventilation solenoid valve 16; The negative pressure aeration box 6 performs the second step, and at the same time opens the positive pressure cover 28, takes out the cleaned workpiece, and puts in the next workpiece of the same model to be cleaned. The staff visually judges the part with the most dirt on the workpiece, and when putting the workpiece into the cleaning tank 1, aligns the part with the most dirt on the workpiece with a drawn antinode marking line; then closes the positive pressure cover 28; After the second step is completed for the negative pressure aeration box 6, the third step and the fourth step are re-executed; During the execution of the fourth step, when the positive pressure cleaning time reaches the cleaning time, the staff observes the most contaminated part of the workpiece through the observation window 33; If the cleaning effect of the part with the most dirt on the workpiece meets the requirements, the fifth step is executed again; If the staff determines that the part of the workpiece with the most dirt needs further cleaning, the electronic control device 2 controls the frequency of the ultrasonic wave to be stable at the set cleaning center frequency for fixed-frequency cleaning. At this time, a standing wave is formed in the cleaning liquid and the part of the workpiece with the most dirt is located at the anti-trend position, so that the energy of ultrasonic cleaning and the cavitation effect are more concentrated on the part of the workpiece with the most dirt, thereby improving the cleaning effect of the part of the workpiece with the most dirt. After the fixed-frequency cleaning is performed for three to five minutes, the cleaning work on the workpiece is ended and the fifth step is re-executed.

[0059] Since cleaning is performed in a positive pressure environment using a degassed cleaning fluid (rather than directly performing negative pressure cleaning in a negative pressure environment, which fails to utilize the mechanism of positive pressure cleaning to improve cleaning efficiency and effectiveness), the present invention not only has the advantages of negative pressure degassing cleaning, but also utilizes positive pressure cleaning for the first time to further increase the cleaning depth of the workpiece, reduce the number of free bubbles in the cleaning fluid, and enhance the cavitation effect, thereby further improving the efficiency and effectiveness of ultrasonic cleaning.

[0060] In the present invention, the frequency of the ultrasonic wave oscillates up and down around the central frequency, so that the standing wave cannot be stably formed, and a uniform cavitation effect is formed in all parts of the cleaning liquid, thereby improving the uniformity of cleaning.

[0061] The present invention comprehensively utilizes variable frequency cleaning to eliminate standing waves and improve the uniformity of cleaning at all locations of the workpiece. At the same time, the present invention also comprehensively utilizes the antinodes of standing waves to concentrate more cleaning capacity on the most contaminated locations of the workpiece, generating a stronger cavitation effect there while keeping the overall power constant, thereby improving the cleaning efficiency (speed) and cleaning effect (contaminant removal rate) at the most contaminated locations of the workpiece.

[0062] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A positive and negative pressure ultrasonic cleaning system for water conservancy projects, comprising a cleaning tank, an electric control device is arranged on the upper part of the side wall of the cleaning tank, and a plurality of ultrasonic transducers are evenly embedded on the bottom wall of the cleaning tank, characterized in that: The top section of the cleaning tank is circular, a frequency-modulated ultrasonic generator is installed on the upper part of the side wall of the cleaning tank, the electric control device is connected to the frequency-modulated ultrasonic generator, and the frequency-modulated ultrasonic generator is connected to each ultrasonic transducer through a wire; the electric control device is connected to a display screen; The cleaning tank is connected to a negative pressure aeration tank through a cleaning liquid exchange mechanism. A positive pressure generating structure is provided on the top of the cleaning tank, and a negative pressure generating structure is provided on the top of the negative pressure aeration tank. The cleaning liquid exchange mechanism is used for two functions, AB. The function of A is to send the cleaning liquid that has been aerated by negative pressure into the cleaning tank to perform ultrasonic cleaning on the parts of the water conservancy project; The function of B is to send the cleaning liquid that has been cleaned under positive pressure and dissolved with a certain amount of gas into the negative pressure aeration box for negative pressure aeration and degassing.

2. The positive and negative pressure ultrasonic cleaning system for water conservancy projects according to claim 1 is characterized in that: The cleaning liquid exchange mechanism includes a connecting pipe, a second filter cover is provided at the bottom of one side of the cleaning tank, and a liquid extraction cavity is formed between the second filter cover and the inner wall of the cleaning tank. One end of the connecting pipe is connected to the liquid extraction cavity at the bottom of the cleaning tank and the other end is connected to the negative pressure aeration tank; A filter, a two-position three-way solenoid valve at the inlet end, a liquid pump and a two-position three-way solenoid valve at the outlet end are sequentially arranged on the connecting pipe from the negative pressure aeration box to the cleaning tank; the two-position three-way solenoid valve at the inlet end and the two-position three-way solenoid valve at the outlet end are both connected to the electric control device; The two-position three-way solenoid valve at the inlet end is connected to the cleaning tank through the first bypass pipe; the inlet of the liquid pump is selectively connected to the negative pressure aeration tank or the cleaning tank through the two-position three-way solenoid valve at the inlet end; The two-position three-way solenoid valve at the outlet is connected to the negative pressure aeration tank through the second bypass pipe, and the outlet of the liquid pump is selectively connected to the cleaning tank or the negative pressure aeration tank through the two-position three-way solenoid valve at the outlet; A first ventilation pipe is connected to the top of the negative pressure aeration box, and a first ventilation solenoid valve is provided on the first ventilation pipe; A second ventilation pipe is connected to the top of the cleaning tank, and a second ventilation solenoid valve is arranged on the second ventilation pipe; the first ventilation solenoid valve and the second ventilation solenoid valve are both connected to the electric control device.

3. The positive and negative pressure ultrasonic cleaning system for water conservancy projects according to claim 2 is characterized in that: The top section of the negative pressure aeration box is circular and has external threads; The negative pressure generating mechanism includes a negative pressure top cover threadedly connected to the top of the negative pressure aeration box. The negative pressure top cover is provided with a vacuum pump and an electronic negative pressure gauge. The electronic negative pressure gauge is used to monitor the pressure in the negative pressure aeration box. The vacuum pump is connected to an exhaust pipe. The exhaust pipe is provided with an exhaust solenoid valve. The exhaust pipe passes through the negative pressure top cover and extends into the negative pressure aeration box.

4. The positive and negative pressure ultrasonic cleaning system for water conservancy projects according to claim 3 is characterized in that: A first filter cover is provided at the bottom of the negative pressure aeration box, and a micro-circulation pump is provided in the first filter cover. The inlet of the micro-circulation pump is communicated with the bottom of the negative pressure aeration box, and the outlet of the micro-circulation pump is connected with a hard vertical pipe. The vertical pipe is connected with multiple layers of horizontally arranged aeration disks from top to bottom, and the diameter of each layer of aeration disk increases step by step from top to bottom; the top end of the vertical pipe is opened at the uppermost aeration disk; the vacuum pump, electronic negative pressure gauge, exhaust solenoid valve and micro-circulation pump are all connected with the electronic control device.

5. The positive and negative pressure ultrasonic cleaning system for water conservancy projects according to claim 4, characterized in that: The top cross-section of the cleaning tank is circular and has an external thread; the positive pressure generating structure includes a positive pressure top cover threadedly connected to the top of the cleaning tank, on which an air pump and an electronic pressure gauge are provided, and the electronic pressure gauge is used to monitor the pressure in the cleaning tank; the air pump is connected to an air supply pipe, on which an air supply solenoid valve is provided, and the air supply pipe passes through the positive pressure top cover and extends into the cleaning tank; the air pump, the electronic pressure gauge and the air supply solenoid valve are all connected to the electronic control device.

6. The positive and negative pressure ultrasonic cleaning system for water conservancy projects according to claim 5, characterized in that: The side wall of the cleaning tank is provided with a vertically arranged observation window, and a number of vibration sensors are installed on the observation window from top to bottom at intervals. Each vibration sensor is used to sense the vibration intensity at its position so as to locate the antinode of the standing wave at the position with the strongest vibration; each vibration sensor is connected to the electronic control device.

7. A cleaning method using the positive and negative pressure ultrasonic cleaning system for water conservancy projects as claimed in claim 6, characterized in that Follow these steps: The first step is the preparation step: the parts of the water conservancy project to be cleaned are called workpieces; collect all the workpieces of the same model to be cleaned, put the first workpiece into the cleaning tank, inject cleaning liquid into the negative pressure aeration tank, cover the positive pressure top cover and the negative pressure top cover, and keep all valves in the closed state; The second step is the negative pressure aeration degassing step: Start the micro-circulation pump to pump the cleaning liquid at the bottom of the negative pressure aeration box to the top aeration plate. The cleaning liquid is spread out on the top aeration plate and falls from the edge of the top aeration plate to the adjacent aeration plate on the lower layer and spread out. The cleaning liquid is spread out on each layer of aeration plates and falls down layer by layer until it falls back into the cleaning liquid from the bottom aeration plate. Start the vacuum pump to evacuate the negative pressure aeration box, thereby reducing the pressure in the negative pressure aeration box; when the electronic pressure gauge detects that the pressure in the negative pressure aeration box is lower than or equal to the predetermined target negative pressure, turn off the vacuum pump and the exhaust solenoid valve; Each layer of aeration disc provides space for the cleaning liquid to be spread out in multiple layers. The cleaning liquid falls layer by layer to form a multi-layer liquid curtain, thereby increasing the contact area between the cleaning liquid and the gas in the negative pressure aeration box, and combining the negative pressure environment to improve the degassing efficiency and degassing effect; The third step is to send the degassed cleaning solution into the cleaning tank; The fourth step is a positive pressure cleaning step; The fifth step is a cyclic cleaning step, replacing the next workpiece of the same type, and repeating the second to fourth steps until the cleaning of all workpieces of the same type is completed.

8. The cleaning method according to claim 7, characterized in that: The third step is specifically: Turn off the vacuum pump, open the first ventilation solenoid valve and the second ventilation solenoid valve, so that the inlet of the liquid pump is connected to the negative pressure aeration tank through the two-position three-way solenoid valve at the inlet end, and the outlet of the liquid pump is connected to the cleaning tank through the two-position three-way solenoid valve at the outlet end; Turn on the liquid pump to send the cleaning liquid in the negative pressure aeration tank into the cleaning tank; the staff sets the corresponding cleaning liquid level for the same type of workpiece; Observe the liquid level in the cleaning tank through the observation window, and when the liquid level reaches the cleaning liquid level, close the liquid pump, the first ventilation solenoid valve and the second ventilation solenoid valve.

9. The cleaning method according to claim 8, characterized in that: The fourth step is specifically: turning on the air pump and the air supply solenoid valve to increase the air pressure in the cleaning tank; when the pressure in the cleaning tank is higher than or equal to the predetermined target positive pressure, turning off the air pump and the air supply solenoid valve; The electronic control device controls the frequency-modulated ultrasonic generator to emit an electrical signal with a certain frequency and transmits it to each ultrasonic transducer. Each ultrasonic transducer generates ultrasonic waves of the same frequency. For specific types of workpieces, the staff sets the central frequency and cleaning time for cleaning. When the first workpiece of the same model is being cleaned, the staff controls the ultrasonic frequency to the central frequency for cleaning through the electronic control device and the frequency-modulated ultrasonic generator, and a standing wave is formed in the cleaning liquid. Then the readings of each vibration sensor are observed on the display screen to determine the location of each antinode of the standing wave, and a marker is used to draw an antinode marking line at the corresponding position of the observation window, which provides a basis for subsequent workpieces of the same model to use the antinode to clean stubborn dirt. After the antinode marking line is drawn or when the subsequent workpiece of the same model begins to be cleaned, the frequency of the ultrasonic wave is controlled by the electronic control device to oscillate up and down around the center frequency to weaken the standing wave phenomenon and improve the uniformity of cleaning; When the positive pressure cleaning time reaches the cleaning time, turn off the frequency-modulated ultrasonic generator and each ultrasonic transducer to complete the fourth step.

10. The cleaning method according to claim 9, characterized in that: The fifth step is specifically: open the first ventilation solenoid valve and the second ventilation solenoid valve, so that the inlet of the liquid pump is selectively connected to the cleaning tank through the two-position three-way solenoid valve at the inlet end, and the outlet of the liquid pump is selectively connected to the negative pressure aeration tank through the two-position three-way solenoid valve at the outlet end; turn on the liquid pump to send the cleaning liquid in the negative pressure aeration tank into the cleaning tank, and then close the first ventilation solenoid valve; For the negative pressure aeration box, the second step is performed, and the positive pressure top cover is opened at the same time, the cleaned workpiece is taken out, and the next workpiece of the same model to be cleaned is placed. The staff visually judges the part with the most dirt on the workpiece, and when placing the workpiece into the cleaning tank, the part with the most dirt on the workpiece is aligned with a drawn antinode marking line; then the positive pressure top cover is closed; After the second step is completed for the negative pressure aeration box, the third and fourth steps are re-executed; During the execution of the fourth step, when the positive pressure cleaning time reaches the cleaning time, the staff observes the most contaminated part of the workpiece through the observation window; If the cleaning effect of the part with the most dirt on the workpiece meets the requirements, the fifth step is executed again; If the staff determines that the part of the workpiece with the most dirt needs further cleaning, the frequency of the ultrasonic wave is controlled by the electronic control device to be stable at the set cleaning center frequency for fixed-frequency cleaning. At this time, a standing wave is formed in the cleaning liquid and the part of the workpiece with the most dirt is located at the anti-trend position, so that the energy of ultrasonic cleaning and the cavitation effect are more concentrated on the part of the workpiece with the most dirt, thereby improving the cleaning effect of the part of the workpiece with the most dirt. After the fixed-frequency cleaning is performed for three to five minutes, the cleaning work on the workpiece is ended and the fifth step is performed again.

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