JP2000239872A - Method and device for aqueous degreasing cleaning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous degreasing cleaning method and a device therefor in which no traces are left on a surface of a work to be cleaned, and a water discharging device can be dispensed with. SOLUTION: The device comprises a cleaning tank 3 filled with an aqueous cleaning solution 2, an elevator device 4 as a means for immersing a work to be cleaned in the cleaning solution 2 and efficiently degreasing and cleaning the work, shower nozzles 7a, 7b which are shower means to spray shower of the aqueous cleaning solution 2 against the work taken out of the cleaning solution 2, and a mist spraying nozzle 14 which is a means to spray pure water in a mist manner. The mist of pure water atomized in a mist manner is adhered to the surface of the work to form a pure water film, and a trace composition can be totally removed with a small volume of pure water by the spray rinse to flow away pollution composition without any water discharging device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved method and apparatus for degreasing and cleaning an object to be treated to which oil has adhered using an aqueous cleaning liquid, and particularly to a method for preventing a stain from remaining on the surface of the object to be treated and a wastewater treatment apparatus. The present invention relates to an aqueous degreasing and cleaning method and apparatus that are not required.

[0002]

2. Description of the Related Art Conventionally, steam cleaning using 1,1,1-trichloroethane or a chlorine-based organic solvent having high cleaning performance has been used as a degreasing cleaning method for metal materials or the like to which oil has adhered. However, it has been found that such organic solvents cause environmental destruction such as destruction of the ozone layer, and their use has been banned or strictly regulated, and various alternative cleaning methods have been developed.

[0003] Current alternative cleaning methods include alkali,
A water-based cleaning using an aqueous solution of a surfactant and a cleaning method using a hydrocarbon-based solvent are often employed. But,
The latter hydrocarbon solvents are flammable and their use is restricted. Therefore, at present, the former water-based cleaning method is often used. FIG. 5 shows an example of a step of removing chips and cutting oil by a water-based cleaning method. In general, in a cleaning process, a degreasing cleaning is performed by using a weak alkaline cleaning agent to perform showering, ultrasonic cleaning, or the like. If the stain on the surface of the product is a problem, the rinsing step with water is performed once or twice thereafter. As the rinsing means, a shower or an ultrasonic wave is used in addition to the vertical swing. After rinsing, blow off as much water as possible with an air blow, and then blow dry with hot air.

[0004]

In the conventional aqueous degreasing method, a large amount of tap water or pure water is used as a shower in the rinsing step. Usually, Ca, Na, S in tap water
i, Cl, etc. are contained in an ionized state, and only moisture evaporates during drying, and Ca, Na, Si, Cl, etc. are concentrated, and finally become water spots (water marks) to be cleaned. However, there is a problem that it is difficult to obtain a good surface quality because it remains on the surface of the film, which may affect a subsequent process.

Also, in the method of shower rinsing with pure water, if the alkaline cleaning agent and the surfactant used in the degreasing cleaning step are not completely removed, ions remain and water marks are generated. To avoid leaving a watermark, a large amount of pure water must be used to rinse the entire surface of the object to be cleaned. Need to be neutralized and discarded. However, in general, there are few places where a wastewater treatment device is provided, and a large amount of equipment and running costs are required for construction and maintenance of the wastewater treatment device.

Conventionally, rinsing using steam has been attempted. However, this method requires a boiler for generating steam, and further requires drainage treatment of a cleaning solution in which steam condenses and overflows. As described above, there is a problem that the equipment cost and the running cost are required. For the above reasons, when water spots (watermarks) on the object to be treated become a problem, hydrocarbon-based cleaning had to be selected despite concerns about safety. .

Accordingly, the present invention has been made in view of such conventional problems, and provides an aqueous degreasing method and apparatus which do not leave stains on the surface of an object to be cleaned and do not require a wastewater treatment apparatus. It is intended to be.

[0008]

According to a first aspect of the present invention, there is provided a water-based degreasing method for cleaning an object to which oil has been adhered using a water-based cleaning liquid, followed by pure water spraying. It is characterized by rinsing. Claim 2
The aqueous degreasing cleaning method according to the step of immersing in a water-based cleaning liquid in a cleaning tank to perform degreasing cleaning, a step of withdrawing from the cleaning liquid and showering, and then spraying pure water in a spray form to spray the cleaning object, Spray rinsing step of cleaning the surface.

A water-based degreasing cleaning device according to a third aspect of the present invention provides a cleaning tank containing an aqueous cleaning liquid, means for immersing the object in the cleaning liquid to perform degreasing cleaning, and a method for cleaning the object removed from the cleaning liquid. It is characterized by comprising shower means for spraying a shower of an aqueous cleaning liquid, and spray rinsing means for spraying pure water in a spray form.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of the water-based degreasing and cleaning apparatus of the present invention. The water-based degreasing cleaning device 1 includes a cleaning tank 3 having an upper space and storing a water-based cleaning liquid 2. As the aqueous cleaning liquid 2 here, water may be used alone, but if necessary (in the case of a hot quenching oil having a high boiling point), an anionic surfactant or a nonionic surfactant may be used. Any of a surfactant, a cationic surfactant and an amphoteric surfactant may be used alone or in combination. Alternatively, a small amount of a weak alkaline detergent may be added. Thereby, separation of the attached oil from the metal surface is promoted, and the cleaning ability can be enhanced.

An opening / closing door 3A is provided on a side surface of the cleaning tank 3 for taking in and out a work as an object to be processed.
Inside the cleaning tank 3, an elevator device 4 serving as an elevating device and a swinging device is disposed as a means for immersing the work in the cleaning liquid 2 for efficient degreasing and cleaning. The elevator apparatus 4 includes an elevator frame 4A on which a basket 5 for accommodating a work is mounted, and a drive cylinder 4B mounted on an upper portion of the cleaning tank 3 for driving the elevator frame up and down and swinging up and down.

A shower nozzle 7a is provided on the ceiling of the washing tank 3 as a rinsing shower means for spraying a shower of a water-based washing liquid from above onto the work housed in the basket 5 raised in the upper space. Is installed, and a shower nozzle 7b that sprays a shower of an aqueous cleaning liquid on the side wall of the upper space from the side of the work.
Is installed. Each shower nozzle 7a, 7b has
The cleaning liquid 2 in the cleaning tank 3 is circulated and supplied by a shower / jet pump 9 connected via a pipe 7c and a three-way switching valve 8, respectively, and the cleaning liquid 2 is jetted. Further, on the lower side surface of the cleaning tank 3 containing the cleaning liquid 2, a number of jet nozzles 10 are arranged so as to surround the elevator frame 4A immersed in the cleaning liquid 2.
The cleaning liquid 2 pumped by the shower / jet pump 9 is circulated through the three-way switching valve 8 and the pipe 10a to form a jet.

On the other hand, an air nozzle 1
1, air supplied by a blower 12 is guided through a pipe 11a, and is continuously injected into the cleaning liquid 2 to generate a large number of bubbles. The cleaning liquid 2 is vigorously stirred by the air bubbling action of the rising bubbles to accelerate degreasing from the work. A floating oil removal nozzle 13 is provided at the level of the cleaning liquid 2 in the cleaning tank 3 so that the oil floating on the liquid surface is separated from the cleaning liquid 2 and discharged. In addition, as the air nozzle 11,
In addition to a nozzle for injecting relatively large air bubbles for air bubbling, extremely high air bubbles are continuously discharged into the cleaning liquid 2 to adhere to oil particles degreased from the work, thereby promoting oil floating. A micro air nozzle for separation (for example, one using a sintered metal filter or the like) can also be provided.

The water-based degreasing / cleaning apparatus 1 of the present invention comprises:
In addition to a means for immersing the work in the cleaning liquid to perform degreasing cleaning and a shower means for removing and rinsing the work from the cleaning liquid, a spray rinsing means for performing a final rinse by spraying pure water in a spray state is further provided. The spray rinsing means is constituted by a mist spray nozzle 14, for example, by mixing and spraying two fluids of pure water and air to generate fine mist (fog) of fine pure water having an average particle diameter of 100 microns or less. A two-fluid nozzle (commercially available) that can wet the surface of the liquid can be suitably used. The mist spray nozzle 14 is provided so as to surround the basket 5 in the upper space of the washing tank 3, and a supply pipe of pure water supplied from a compressed air pipe 14 a and a pure water device (not shown) through a switchable filter 15. 14b is connected. The branch pipe 1 of the pure water supply pipe 14b
4c is connected to the bottom of the cleaning tank 3,
b, 14c are supplied to the respective on-off solenoid valves 16, 17
It can be switched by using.

Next, a description will be given of a degreasing cleaning step of the oil adhering to the workpiece by the above-mentioned water-based degreasing cleaning apparatus with reference to a process flowchart shown in FIG. In advance, cleaning tank 3
A water-based cleaning liquid 2 is put in the lower half. Step 1: The door 3A of the cleaning tank 3 is opened, and the basket 5 containing the work is inserted into the lifted elevator frame 4A to close the door 3A. Step 2: First, rough cleaning by a shower is performed. That is, the shower pump / jet pump 9 is started to pump up the cleaning liquid 2 in the tank, and the three-way switching electromagnetic valve 8 and the pipe 7c
After that, a shower of the cleaning liquid 2 is sprayed from the shower nozzles 7a and 7b toward the work in the basket 5 for a predetermined time to wash off the oil adhering to the work. In this rough cleaning process, a large amount of adhering oil is removed from the work and falls together with the cleaning liquid 2 to be mixed into the cleaning liquid 2 at the bottom of the tank. The mixed oil is cleaning liquid 2
Of the floating oil removal nozzle 13
From the washing tank 3. Step 3: Next, the drive cylinder 4B is operated to lower the elevator frame 4A, and the basket 5 is immersed in the aqueous cleaning liquid 2 in the cleaning tank 3. Then, while immersed, the drive cylinder 4B is operated within a limited stroke range to swing the basket 5 up and down. At the same time, the three-way switching electromagnetic valve 8 is switched to the pipe 10a so that the cleaning liquid 2 is jetted from the jet nozzle 10. Further, the blower 12 is started to send a large amount of air from the pipe 11 a to the air nozzle 11, thereby ejecting a large amount of bubbles into the cleaning liquid 2. The oil adhering to the surface of the object to be processed is peeled off by the cooperative action of the pulsation and the jet in the cleaning liquid. If a surfactant or a weak alkaline detergent is added to the aqueous cleaning liquid 2, removal of the adhering oil is promoted. After swinging for a predetermined time, the elevator frame 4A is raised above the liquid level. During the rising, the jet from the jet nozzle 10 is continued to prevent the oil once separated from re-adhering to the surface of the workpiece. In addition, when the air nozzle 11 is used not only with a nozzle for discharging large bubbles for air bubbling but also with a micro air nozzle for oil floating separation, the separation of oil adhering by air bubbling and the floating of separated oil by fine bubbles are promoted. Is also performed. In that case, the separation of the adhered oil by the rocking and the air bubbling is separated, and the floating of the separated oil by the fine bubbles is promoted by using the micro air nozzle while the basket 5 is gently immersed in the cleaning liquid 2 (standby standby). It is preferred to do so.

The above steps 2 to 3 are the degreasing and cleaning process. Step 4: When pulled above the liquid surface of the dip tank 11 to be treated for a predetermined time period injecting a treatment object to wash shower from the shower nozzle 12 by driving the shower pump P _1. As a result, the deposits remaining on the surface of the workpiece are washed away. Step 4 is a shower process for finish cleaning. The cleaning liquid 2 used in the steps up to here (steps 2 to 4) is all circulated and used in the cleaning tank 3. When the cleaning liquid in the same cleaning tank is repeatedly used while being circulated in this way, dirt dissolves and accumulates in the cleaning liquid as the number of times of cleaning increases, so when the shower cleaning is performed and then the drying is performed, the work surface is noticeably stained. Become like The process proceeds to the next step 5 in order to prevent occurrence of this stain. In addition, depending on the degree of contamination of the cleaning liquid 2 in the cleaning tank 3, the opening / closing solenoid valve 17 is opened occasionally to supply new pure water, whereby the progress of the contamination of the cleaning liquid 2 in the tank can be suppressed and used continuously. Step 5: A spray rinsing step. Here, the opening / closing electromagnetic valve 16 is opened, pure water is sent to the mist injection nozzle 14 as a spray rinsing means via a pipe 14b, and a predetermined flow rate of compressed air is supplied via a compressed air pipe 14a. Thereby, a fine mist having an average particle diameter of 100 μm or less is generated from the mist injection nozzle 14. The fine particles of the fog float in the upper space of the cleaning tank 3 and adhere to the surface of the work being lifted from the cleaning liquid 2 in the cleaning tank 3 one after another to form a water film. Then, dirt such as the cleaning liquid 2 and residual oil on the work surface is washed away and rinsed. Floating fog penetrates deeply and in shaded areas that are difficult to reach with ordinary showers, even for intricately shaped or overlapping workpieces. There is no watermark left. The amount of pure water used for the spray rinsing may be such that a part of the cleaning liquid 2 in the cleaning tank 3 flows out from the floating oil removing nozzle 13 together with the separated floating oil and is reduced, and in the case of ordinary shower rinsing, Can be suppressed to 1/50 to 1/100. Therefore, a wastewater treatment device is not required. By the way, in the case of conventional shower rinsing with pure water, a large amount of pure water is required so as to cover the entire surface of the object to be cleaned, and since the pure water used once must be discarded, it overflowed from the cleaning tank. A wastewater treatment device for treating a large amount of cleaning wastewater is required.

The work thus degreased and washed is taken out of the washing tank 3 while being kept in the basket 4, sent to a drying step, and dried by an appropriate drying means such as hot air drying, reduced pressure drying, and suction drying. (Example): Tables 1 and 2 and FIGS. 3 and 4 show that a work which has been subjected to water-based degreasing through the spray rinsing process of the present invention and a conventional water-based degreasing method which requires only pure water shower rinse. An example of a test result obtained by measuring the presence or absence of a stain (watermark) using an energy dispersive X-ray analyzer with respect to a work that has been performed is shown.

[0018]

[Table 1]

Table 1 shows the results of analysis of residual elements on the work surface after degreasing and cleaning according to the present invention and the measurement conditions. FIG.
FIG. 3 is a diagram in which the results of analysis of residual elements on the surface of a workpiece after degreasing and cleaning according to the present invention are recorded.

[0020]

[Table 2]

Table 2 shows the results of analysis of residual elements on the surface of the workpiece after degreasing and cleaning according to the conventional method and the measurement conditions. FIG.
FIG. 3 is a diagram in which the results of analysis of residual elements on the work surface after degreasing and cleaning by a conventional method are recorded. In this test, after the work to which the heat-treated oil has adhered is subjected to aqueous degreasing and washing, the work is cut in accordance with the size of the sample holder to prepare a test piece, and the test piece is subjected to energy dispersive X-ray. It is set on the analyzer and irradiated with an electron beam, the intensity of characteristic X-rays generated from the test specimen is measured, and qualitative and quantitative analysis of surface deposits such as "stains (water marks)" remaining on the surface is performed. The fact that the intensity of the characteristic X-ray is proportional to the weight concentration of the element contained in the substance is used.

According to the test results, the work surface after the degreasing and cleaning by the conventional method has F
In addition to the e element, in particular, many residual elements such as Na, Si, and Cl were detected, indicating the presence of a watermark. On the other hand, on the work surface after the degreasing cleaning according to the present invention, only the Fe element, which is a component of the sample body, is detected, and no watermark forming element remains (that is, no watermark is formed). It is clear. Although the residual oil amount is not directly measured, it can be said that there is no residual oil on the work surface since no watermark forming element remains.

In the above embodiment, the case where the heat-treated oil has adhered has been described as an example. However, the present invention is not limited to this and can be suitably used for other degreasing. Further, the object to be processed is not limited to metal, and can be applied to nonmetal. In addition, when an alkaline detergent, a surfactant, or the like is added to the cleaning liquid to increase the degreasing and cleaning performance, the workpiece may not necessarily need to be swung or air bubbled in the degreasing and cleaning step.

[0024]

As described above, according to the present invention,
Pure water spray rinsing is applied to the workpiece degreased and washed with an aqueous cleaning solution, so that rinsing can be performed with a very small amount of water without leaving a watermark, and a wastewater treatment device is not required, reducing equipment and running costs. High quality processing can be obtained while suppressing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an embodiment of a water-based degreasing and cleaning apparatus of the present invention.

FIG. 2 is a process flowchart of an embodiment of the aqueous degreasing cleaning method of the present invention.

FIG. 3 is a diagram showing a result of analysis of residual elements on a work surface after degreasing and cleaning according to the present invention.

FIG. 4 is a diagram in which the results of analysis of residual elements on the work surface after degreasing and cleaning by a conventional method are recorded.

FIG. 5 is a process flowchart for removing chips and cutting oil by a conventional aqueous degreasing method.

[Explanation of symbols]

 Reference Signs List 1 water-based degreasing cleaning device 2 cleaning liquid 3 cleaning tank 4 immersion means 7a shower means 7b shower means 14 spray rinsing means

Claims (3)

[Claims] 1. An aqueous degreasing method comprising the steps of: degreasing and cleaning an object to which oil has adhered with a water-based cleaning liquid; and then performing pure water spray rinsing. 2. A step of immersing the object to be treated with oil in a water-based cleaning liquid in a cleaning tank to perform degreasing cleaning, a step of withdrawing from the cleaning liquid and showering, and then spraying pure water in a spray form. And a spray rinsing step of cleaning the surface of the object to be treated. 3. A cleaning tank containing an aqueous cleaning liquid, means for immersing the object in the cleaning liquid to perform degreasing cleaning, shower means for injecting a shower of the aqueous cleaning liquid onto the object taken out of the cleaning liquid, A water-based degreasing cleaning device comprising: a spray rinsing means for spraying pure water in a spray state.