JP7625972B2 - Cleaning Equipment - Google Patents

Description

The present invention relates to a cleaning device for degreasing and cleaning objects to be cleaned that have oils and greases attached, such as machine parts before surface treatment or after machining, and in particular to a cleaning device for aqueous cleaning that uses both an aqueous cleaning agent and fine bubbles.

Cleaning agents that are mainly composed of fluorocarbon or chlorine-based solvents or hydrocarbon solvents, which have a large environmental impact, are being replaced by aqueous cleaning agents that use water as the main component in combination with physical means. In aqueous cleaning that uses microbubbles as a physical means, the oil and fat are peeled off from the surface of the object to be cleaned by the oil-adsorbing action of the microbubbles, and are floated to the liquid surface by buoyancy. The oil is then collected from the cleaning tank into an oil-water separation tank using a drainage weir, and separated and removed with an oil skimmer. The purified cleaning liquid is then mixed with microbubbles and circulated to the cleaning tank (see, for example, Patent Document 1).

Patent No. 5430286

In a cleaning device that also uses microbubbles, it is necessary to quickly and reliably collect the oil and grease that has been peeled off from the object to be cleaned in the cleaning tank into an oil-water separation tank. However, in the device of Patent Document 1, the cleaning liquid that has been sucked in from the most downstream part of the oil-water separation tank and that contains microbubbles is simply circulated to the bottom of the cleaning tank, and the flow inside the cleaning tank is not taken into consideration, which creates an issue where some of the floating dirt (including sludge and cutting debris) and oil and grease accumulate in the corners of the cleaning tank.

The present invention was made in consideration of these circumstances, and its purpose is to quickly and reliably separate and recover the oil and grease that has risen to the surface in the cleaning tank from the drainage weir.

In order to solve the above problems, the cleaning device of the present invention comprises:
A cleaning tank for storing a cleaning liquid;
a support means for supporting an object to be cleaned at a predetermined position in the cleaning tank while immersed in the cleaning liquid;
a first drainage weir provided on an upper portion of a first partition wall defining one side of the cleaning tank;
a first intermediate tank for receiving the cleaning liquid overflowing from the first drainage weir, and an oil-water separation tank including a means for separating oil and grease from the cleaning liquid;
A circulation means for circulating the cleaning liquid from which the oil and grease components have been separated in the oil-water separation tank back to the cleaning tank;
Equipped with
The circulation means is provided with an injection nozzle for injecting the cleaning liquid sucked from the oil-water separation tank into the cleaning tank while containing fine bubbles,
The spray nozzle is provided adjacent to the lower part of the first partition in the cleaning tank and is oriented so as to cross the lower part of the object to be cleaned by the support means and face the opposite side of the first partition in the cleaning tank.

As described above, the cleaning device according to the present invention is configured to spray cleaning liquid containing fine bubbles from the lower part of the cleaning tank on the same side as the first drainage weir, across the lower part of the object to be cleaned, and toward the other side of the cleaning tank. When the cleaning liquid containing fine bubbles comes into contact with the periphery of the lower part of the object to be cleaned, a flow is induced that rises around the object to be cleaned and along the inner space, and a flow that reaches the other side of the cleaning tank and reverses upward. A flow is formed near the liquid surface in the cleaning tank toward the first drainage weir, and dirt (including sludge and cutting chips) and oil and grease that have risen to the surface in the cleaning tank can be quickly and reliably separated and collected from the first drainage weir into the first intermediate tank.

1 is a schematic cross-sectional plan view showing an internal structure of a cleaning device according to an embodiment of the present invention. 1 is a schematic cross-sectional side view showing an internal structure of a cleaning device according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in Figures 1 and 2, a cleaning device 1 according to an embodiment of the present invention includes a cleaning tank 10 for cleaning an object W to be cleaned (hereinafter simply referred to as an object), an oil-water separation tank 20 for separating dirt and grease from the cleaning liquid, and two systems of circulation means 3 and 4 for circulating the cleaning liquid between them.

The cleaning tank 10 and the oil-water separation tank 20 are defined by dividing the inside of a bottomed rectangular cylindrical tank structure 2, which has a bottom surface 16 and two sets of opposing side walls 17, 18, by a first partition wall 14 approximately in the center, or are constructed and joined by sharing the first partition wall 14.

Inside the cleaning tank 10, there is provided a support means 13 for supporting the object W at a predetermined position. The support means 13 has a support structure that blocks the flow of the cleaning liquid as little as possible, such as a cleaning basket or hook structure made of wire mesh, perforated plate, or wire material, and is configured to be movable up and down by a lifting device (not shown) between a cleaning position (13) shown by a dashed line in the figure and an introduction position 13' shown by a two-dot chain line in the figure. The upper space of the cleaning tank 10, including the introduction position 13', is covered with a shielding structure, and an opening/closing shutter is provided at the entrance 19 for the object W adjacent to the introduction position 13'.

A first drainage weir 15 is formed on the upper part of the first partition 14 of the cleaning tank 10, which is at the rear side of the loading entrance 19, to allow the cleaning liquid stored in the cleaning tank 10 to overflow into the oil-water separation tank 20 (first intermediate tank 21) and to discharge dirt and oil floating near the liquid surface from the cleaning tank 10. This first drainage weir 15 is provided in a notched shape in a part adjacent to one corner of the cleaning tank 10 in the width direction of the first partition 14.

In order to continuously overflow the cleaning liquid in the cleaning tank 10 from the first drainage weir 15, clean cleaning liquid must be continuously circulated and supplied to the cleaning tank 10. As a means for circulating and supplying such cleaning liquid, a supply port 12 for the cleaning liquid circulated by the circulation means 3 and a spray nozzle 11 for the cleaning liquid circulated by the circulation means 4 are provided inside the cleaning tank 10.

The injection nozzle 11 is a supply unit for the cleaning liquid that is pumped through the supply pipe 43 by the pump 42 that constitutes the circulation means 4, and is also a device for generating fine bubbles. Inside the injection nozzle 11, suction occurs due to the separation flow of the pressurized cleaning liquid, and air is sucked in through the air supply pipe 47 and simultaneously sheared, so that it is sprayed into the cleaning tank 10 as cleaning liquid in an air-liquid mixture state that contains fine bubbles. The flow rate of the sucked air is controlled to a predetermined flow rate by the air flow rate adjustment means 46 (air flow meter).

The fine bubbles are preferably spherical bubbles with a diameter of 1 mm or less, particularly fine bubbles (microbubbles) with a diameter of 0.1 mm or less, and can also be nanobubbles. Such fine bubbles have a smaller buoyancy than normal bubbles and carry a negative charge (zeta potential) in the cleaning solution, so they do not disappear immediately but remain dispersed and stably in the cleaning solution. However, to maintain the spherical bubbles more stably in the cleaning solution, a small amount of additives such as alcohol-based compounds and surfactants may be added to the water-based cleaning solution.

As described above, when the negatively charged microscopic bubbles in the cleaning liquid come into contact with the object W, the microscopic bubbles are adsorbed onto the positively charged dirt and oil, and the dirt and oil are captured within the bubbles, which are electrically neutralized and detached from the object W, and rise to the surface of the liquid due to the buoyancy acting on the dirt and oil. In order to quickly and reliably separate and recover the dirt and oil that has risen to the surface of the liquid from the first drainage dam 15, the injection nozzle 11 is arranged as follows.

As shown in Figures 1 and 2, the spray nozzle 11 is disposed adjacent to the lower part of the first partition wall 14 at one corner of the cleaning tank 10 where the first drainage weir 15 is provided, and is oriented so as to cross the lower part of the support means 13 toward the other side of the cleaning tank 10 toward the lower corner of the support means 13 in the cleaning position. The spray nozzle 11 is oriented at an angle of approximately 45 degrees in the horizontal plane or approximately diagonally relative to the side wall 18 and first partition wall 14 of the cleaning tank 10, and at an elevation angle of 10 to 35 degrees relative to the bottom surface 16 of the cleaning tank 10.

On the other hand, the supply port 12 for the cleaning liquid circulated through the supply pipe 33 by the pump 32 constituting the circulation means 3 is provided away from the spray nozzle 11 in another corner adjacent to the first partition 14 in the cleaning tank 10, and opens at the lower end of the supply pipe 33 near the bottom surface 16 at the bottom of the cleaning tank 10, just like the spray nozzle 11.

The inside of the oil-water separation tank 20 is divided into a first intermediate tank 21 and a second intermediate tank 22 by a second partition wall 26, and on the second intermediate tank 22 side, an oil-water separation section 23 and a cleaning liquid intake section 24 are defined by partition walls 28 and 29. An oil skimmer 30 is provided in the oil-water separation section 23 as a means for separating oil and grease from the cleaning liquid.

The first intermediate tank 21 is adjacent to the cleaning tank 10 via the first partition 14, and is configured to receive the cleaning liquid spilled from the first drainage weir 15 of the cleaning tank 10. A second drainage weir 25 is formed on the upper part of the second partition 26 to allow the cleaning liquid received in the first intermediate tank 21 to spill into the second intermediate tank 22 when the liquid level reaches L2 or higher. The height (L2) of the second drainage weir 25 is formed to be the same as or slightly lower than the height (L1) of the first drainage weir 15.

The second drainage weir 25 is adjacent to the side wall 18 away from the first drainage weir 15 and is cut out in a portion of the width of the second partition wall 26. When the cleaning liquid overflows from the second drainage weir 25, a flow of cleaning liquid is formed inside the first intermediate tank 21, particularly near the liquid surface, from the first drainage weir 15 side toward the second drainage weir 25.

A water intake 31 for a pump 32 constituting the circulation means 3 is provided at the bottom of the first intermediate tank 21 adjacent to the first drainage weir 15. The cleaning liquid sucked in from the water intake 31 by the operation of the pump 32 is filtered by a filter 34 and pumped through a supply pipe 33 to the supply port 12, from which it is circulated into the cleaning tank 10.

The second intermediate tank 22 is adjacent to the first intermediate tank 21 via the second partition 26, and is configured to receive the cleaning liquid that has overflowed from the second drainage weir 25 of the first intermediate tank 21. The oil-water separation section 23 and the cleaning liquid intake section 24 are adjacent to the downstream side of the second intermediate tank 22 via the partition 28, and the second intermediate tank 22 and the oil-water separation section 23 are connected through the communication section 27 located on the side of the partition 28 away from the second drainage weir 25. Therefore, the second intermediate tank 22, the oil-water separation section 23, and the cleaning liquid intake section 24 are at the same liquid level L3. This liquid level L3 is monitored by a liquid level gauge 45 provided in the cleaning liquid intake section 24.

The second intermediate tank 22 has the function of floating up the oil and grease components of the cleaning liquid that has overflowed from the second drainage weir 25 of the first intermediate tank 21 and guiding them to the oil skimmer 30 in the oil-water separation section 23. As the oil skimmer 30, a belt type in which the oil and grease components are adsorbed onto an endless belt made of an oleophilic material such as a metal belt and the oil and grease components are scraped off and removed from the belt by a scraper outside the cleaning liquid is preferable, but other types of oil skimmers such as a float type, disk type, or drum type can also be used.

The cleaning liquid intake section 24 is separated from the oil-water separation section 23 by a bulkhead 29 at its upper part, which includes the range of liquid level fluctuations except for the lower part, and is connected to the oil-water separation section 23 below the bulkhead 29. The oil and grease in the cleaning liquid floats near the liquid surface and cannot flow into the cleaning liquid intake section 24 from the bulkhead 29. Only the cleaning water that has been purified by separating the oil and grease with the oil skimmer 30 flows into the cleaning liquid intake section 24 from the communication section below the bulkhead 29.

The cleaning liquid intake section 24 is provided at its lower part with an intake port 41 for a pump 42 that constitutes the circulation means 4. The cleaning liquid sucked in from the intake port 41 by the operation of the pump 42 is filtered by a filter 44 and pumped through a supply pipe 43 to the spray nozzle 11, from which it is configured to be circulated within the cleaning tank 10 in a state containing fine air bubbles.

The pumps 32, 42 of the two circulation means 3, 4 are linked to the lifting device of the support means 13 and are sequence-controlled by a control device (not shown). That is, the object W is supported on the support means 13' at the introduction position, and the support means 13 is lowered by closing the shutter 19 or other operation to start a predetermined cleaning process, and when the cleaning process is completed, the support means 13 is raised and the object W can be removed.

Next, we will explain the operation of the cleaning device based on the above embodiment.

During the cleaning process, the pump 32 of the circulation means 3 is constantly operating, and the cleaning liquid in the first intermediate tank 21 is constantly circulated and supplied from the supply port 12, so that the liquid level L1 in the cleaning tank 10 is maintained near full capacity, and the cleaning liquid overflows from the first drainage weir 15 to the first intermediate tank 21, resulting in a flow toward the first drainage weir 15 near the liquid level in the cleaning tank 10.

On the other hand, the pump 42 of the circulation means 4 operates intermittently only during cleaning. However, when the cleaning liquid is replaced, such as during the first cleaning, the pump 42 may be operated in advance to make the cleaning liquid in the cleaning tank 10 (and the first intermediate tank 21) into a gas-liquid mixed state containing fine bubbles.

In this state, the support means 13 supporting the object W is lowered, immersing the object W in the cleaning liquid. At the same time, the pump 42 of the circulation means 4 is operated to spray the cleaning liquid containing fine bubbles from the spray nozzle 11. As shown by the arrows in Figures 1 and 2, a flow of cleaning liquid is induced that surrounds the object W from below and rises along the periphery (and the inner space) of the object W, and a flow that crosses the bottom and periphery of the object W and reaches the other side of the cleaning tank 10 (the side wall 17 opposite the first drainage weir 15) and reverses upward. Dirt and oil that are adsorbed by the bubbles upon contact with the object W and peeled off from the object W rise to the liquid surface.

Near the liquid surface of the cleaning tank 10, in addition to the overflow flow of the cleaning liquid constantly circulated and supplied from the supply port 12, the cleaning liquid sprayed from the spray nozzle 11 forms a flow toward the first drainage weir 15 as shown by the two-dot chain line in the figure, and this flow of cleaning liquid quickly and reliably drains dirt and grease that has risen to the surface into the first intermediate tank 21.

In addition, while the object W is being washed, the cleaning liquid in the oil-water separation tank 20 is supplied to the washing tank 10 by spraying the cleaning liquid from the spray nozzle 11, so the liquid level L2 in the first intermediate tank 21 is also maintained near full capacity, and an overflow of the cleaning liquid from the second drainage weir 25 to the second intermediate tank 22 is formed, resulting in a flow toward the second drainage weir 25 near the liquid level.

Therefore, dirt and grease that flow into the first intermediate tank 21 move toward the second drainage weir 25 while floating near the liquid surface, and are discharged from the second drainage weir 25 into the second intermediate tank 22. Therefore, even if the cleaning liquid is sucked in from the water intake 31 by the operation of the pump 32 of the circulation means 3, dirt and grease will not be mixed in.

The second intermediate tank 22 is connected to the oil-water separation section 23 and the cleaning liquid intake section 24, so that the cleaning liquid in the second intermediate tank 22 flows from the second drainage weir 25 side to the oil-water separation section 23 side due to the intake of cleaning liquid from the intake port 41 by the operation of the pump 42 of the circulation means 4 and the inflow of cleaning liquid from the second drainage weir 25. Therefore, the dirt and oil that flowed into the second intermediate tank 22 together with the cleaning liquid move toward the oil-water separation section 23, where they are collected by the oil skimmer 30 and separated and removed.

When the cleaning process in the cleaning tank 10 is completed for a predetermined time, the pump 42 of the circulation means 4 is stopped, the spraying of cleaning water and fine bubbles from the spray nozzle 11 is also stopped, and the support means 13 is raised to pull the object W out of the cleaning liquid. At this time, the liquid level L1 of the cleaning liquid in the cleaning tank 10 temporarily drops, but as described above, the pump 32 of the circulation means 3 continues to operate, and the liquid level L1 of the cleaning liquid is restored to near full capacity before the next object W is added. In addition, even after the spraying of the cleaning liquid and fine bubbles from the spray nozzle 11 is stopped, the fine bubbles in the cleaning tank 10 do not disappear in a short time, but remain dispersed in the cleaning liquid in a gas-liquid mixed state, so that in the next cleaning process, cleaning can be performed as rated as soon as the object W is added.

In the initial stage of the cleaning process, when the support means 13 is lowered and the object W is immersed in the cleaning liquid, the cleaning liquid flows around the object W, providing good contact between the object W and the cleaning liquid, and a relatively large amount of dirt and grease is peeled off from the object W. Therefore, the pump 32 of the circulation means 3 is operated in advance, the liquid level L1 of the cleaning liquid is maintained near full capacity, an overflow flow toward the first drainage weir 15 is formed, and fine air bubbles remain in the cleaning liquid to maintain a gas-liquid mixed state, so that a sufficient cleaning effect can be obtained in the initial stage of the cleaning process, and the dirt and grease released from the object W can be reliably separated and collected.

In addition, by using the pump 32 of the circulation means 3 to circulate the cleaning liquid from the first intermediate tank 21 to the cleaning tank 10, there is no need to constantly operate the pump 42 of the circulation means 4 to maintain overflow from the first drainage weir 15, and the cleaning liquid can be circulated to the cleaning tank 10 without relying on the processing capacity of the oil skimmer 30. Also, since only a partial amount of the cleaning liquid circulates to the oil-water separation section 23 side, there is a surplus in the processing capacity of the oil skimmer 30.

In addition, by having the cleaning liquid spilling out of the cleaning tank 10 received in the first intermediate tank 21 and then flowing into the second intermediate tank 22, fluctuations in the liquid level L3 from the second intermediate tank 22 onwards are reduced, and dirt and oil can be guided to the oil skimmer 30 in a state where they are sufficiently floated.

As a specific example, in the case of an object (such as a cylinder block) that requires a single cleaning process of 4 to 5 minutes, spraying from the spray nozzle 11 for about 20 seconds each time the object is added fills the cleaning tank with fine bubbles, and it has been confirmed that the fine bubbles remain in the cleaning liquid for 3 to 4 minutes thereafter. Therefore, by spraying from the spray nozzle 11 continuously or intermittently at the beginning of the cleaning process, it is possible to achieve the desired cleaning effect while also reducing power costs by shortening the pump operating time.

The cleaning device 1 is expected to be used for pre-treatment and in-process cleaning in metal surface treatment processes such as anodizing, plating, and pickling, as well as for cleaning metal parts after machining such as cutting and pressing. In aqueous cleaning, alkaline, neutral, or acidic cleaning solutions are used depending on the purpose of the cleaning.

Microbubbles (fine bubbles) have the property of taking on a positive charge when the cleaning solution is acidic at or below pH 4, and a negative charge when the solution is above that. This also depends on the particle size of the bubbles, and the smaller the particle size, the greater the change in electric potential. For example, microbubbles with diameters of 1 to 40 μm have the property of shrinking, and the change in electric potential at that time is large. Under such circumstances, the microbubbles take on a positive charge, which attracts anions, sludge, oil, dirt, and other substances with the opposite charge to their surroundings.

On the other hand, in a cleaning solution with a pH of 4 or higher, by taking advantage of the characteristic that microscopic bubbles are negatively charged, if a chemical that is attracted to negative charges (which carries a positive charge) is added, the chemical can be circulated together with the microscopic bubbles in the cleaning tank 10 or in any tank thereafter.

Therefore, we used butylbenzoic acid, which has an anti-rust effect, as a positively charged additive and conducted an experiment to compare the content of the additive with and without micro-bubbles. When using a water-based cleaning solution in a cleaning device that includes piping for circulating the cleaning solution, anti-rust is necessary, but because butylbenzoic acid has a specific gravity slightly greater than that of water, it tends to accumulate at the bottom of the cleaning tank. Therefore, if this tendency can be improved by using micro-bubbles, it is thought that this will lead to improved anti-rust effects.

In the experiment, 0.2 g/l of butylbenzoic acid was added to the cleaning water, and the two pumps were operated for 20 minutes. After 5 minutes, the cleaning liquid was sampled from the top (near the liquid surface) and middle of the cleaning tank, and the butylbenzoic acid content was measured using the hexane extraction method. The results are as follows:

Butyl benzoic acid content (mg/l)
No bubbles Bubbles Highest 3.1 9.6
Medium 1.5 1.3

The experimental results showed that when there were bubbles, the content at the top of the cleaning tank was more than three times higher than when there were no bubbles, and by utilizing the properties of fine bubbles to transmit additives, it is expected that the rust prevention effect will be improved.

In the above embodiment, the case where there are two systems of circulating means 3, 4 for the cleaning liquid has been described, but the circulating means 3 from the water intake 31 in the first intermediate tank 21 to the supply pipe 12 can be omitted, and the system can be configured with only one system of circulating means 4. In that case, the second drainage weir 25 must be a communication part that connects to the bottom at that position, so that the liquid level L2 in the first intermediate tank 21 is the same as the liquid level L3 in the second intermediate tank 22 and beyond.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications and variations are possible within the scope of the present invention.

REFERENCE SIGNS LIST 1 Cleaning device 3, 4 Circulation means 10 Cleaning tank 11 Injection nozzle 12 Supply port 13 Support means 14 First partition 15 First drainage weir 20 Oil-water separation tank 21 First intermediate tank 22 Second intermediate tank 23 Oil-water separation section 24 Cleaning liquid intake section 25 Second drainage weir 26 Second partition 30 Oil skimmer 31, 41 Intake port 32, 42 Pump 33, 43 Supply pipe 34, 44 Filter 45 Liquid level gauge 46 Air flow rate adjustment means

Claims (5)

A cleaning tank for storing a cleaning liquid;
a support means for supporting an object to be cleaned at a predetermined position in the cleaning tank while immersed in the cleaning liquid;
a first drainage weir provided on an upper portion of a first partition wall defining one side of the cleaning tank;
a first intermediate tank for receiving the cleaning liquid overflowing from the first drainage weir, and an oil-water separation tank including a means for separating oil and grease from the cleaning liquid;
A circulation means for circulating the cleaning liquid from which the oil and grease components have been separated in the oil-water separation tank back to the cleaning tank;
Equipped with
The circulation means is provided with an injection nozzle for injecting the cleaning liquid sucked from the oil-water separation tank into the cleaning tank while containing fine bubbles,
A cleaning apparatus, wherein the spray nozzle is provided adjacent to a lower portion of the first partition in the cleaning tank and is oriented so as to cross the lower portion of the object to be cleaned by the support means and face the opposite side of the first partition in the cleaning tank. The oil-water separation tank further includes a second intermediate tank for receiving cleaning liquid overflowing from a second drainage weir of the first intermediate tank , and the means for separating the oil and grease components is disposed in the second intermediate tank or downstream thereof,
2. The cleaning device according to claim 1, wherein the circulation means comprises a first circulation means for circulating the cleaning liquid sucked in from a first water intake port downstream of the oil and grease separating means to the spray nozzle, and a second circulation means for circulating the cleaning liquid sucked in from a second water intake port at the bottom of the first intermediate tank to a supply port at the bottom of the cleaning tank. The cleaning apparatus of claim 2, wherein the injection nozzle is provided adjacent to one corner of the lower part of the first partition of the cleaning tank, the supply port is provided adjacent to the other corner of the lower part of the first partition of the cleaning tank, the first drain weir is provided adjacent to one corner of the upper part of the first partition of the cleaning tank, and the second drain weir is provided adjacent to the other corner of the first intermediate tank separated from the first drain weir. a control device that operates the second circulation means so that the liquid level in the cleaning tank is maintained at the first drainage weir and that operates the first circulation means when cleaning an object to be cleaned;
4. The cleaning apparatus according to claim 2 or 3, wherein the second drainage dam is formed to be the same height as or slightly lower than the first drainage dam. The cleaning device according to claim 3, wherein the spray nozzle is oriented at an elevation angle so as to cross the lower part from the lower end corner of the support means toward the other side of the cleaning tank.