JP3801904B2 - Cleaning device and cleaning method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cleaning apparatus and a cleaning method for cleaning electronic parts, mechanical parts, and the like, and more particularly to a cleaning apparatus and a cleaning method for realizing high-performance vacuum ultrasonic cleaning with a hydrocarbon solvent.
[0002]
[Prior art]
Conventionally, it is known to immerse an object to be cleaned in a cleaning tank in which a cleaning liquid is stored, and to vacuum-clean the object to be cleaned. The ultrasonic wave generally means a sound wave of 20 kHz or higher. By using such a high frequency sound wave, water or a solvent is vibrated to wash a complicated shape object or to wash a vulnerable object safely. Ultrasonic cleaning.
[0003]
It is said that there are three effects of ultrasonic cleaning: cavitation, acceleration due to water molecules, etc., and acceleration of physical and chemical reactions such as minute signals of the object to be cleaned. It is said to be expensive. Cavitation is an infinite number of cavities generated when a pressure of a predetermined level or higher is applied to the cleaning liquid, and bubbles such as dissolved oxygen are generated as nuclei.
[0004]
And since the ultrasonic signal forms a standing wave in the cleaning liquid, countless cavitations generated at the position of the large amplitude ultrasonic signal are destroyed inward during the ascent process, and the strong impact force at this time is The cleaning action will be demonstrated.
[0005]
[Problems to be solved by the invention]
Thus, since ultrasonic cleaning is exclusively based on the destruction of the generated cavitation, reducing the pressure of the cleaning tank has only halved its effect. This is because, under reduced pressure conditions, the generated cavitation is always pulled outward, so that it does not break inward but rises as simple bubbles.
[0006]
However, some objects to be cleaned have various shapes and those that are in close contact with each other and are difficult to clean, and there are some that cannot be effectively cleaned by conventional common-sense cleaning methods. For example, an object to be cleaned that does not have an open hole vertically above in the state where it is introduced into the cleaning tank will generate an air pocket, and the cleaning liquid will not reach the air pocket, so that it will not be cleaned at all. Also, the plate material that is in an adhesive state due to oil or the like may not be able to exhibit the cleaning effect because the cleaning liquid does not reach the bonding surface.
[0007]
The present invention has been made in view of the above circumstances, and a main object thereof is to provide a cleaning apparatus and a cleaning method capable of effective cleaning regardless of the shape and the degree of adhesion of an object to be cleaned. .
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a cleaning apparatus according to the present invention includes a cleaning tank capable of immersing an object to be cleaned in a cleaning liquid, a pressure reducing mechanism capable of depressurizing the cleaning tank, and a reduced pressure state of the cleaning tank instantaneously. A depressurizing return pressure mechanism, and in a state in which the object to be cleaned is immersed, operates including a cleaning step of repeating a depressurization state and a return pressure state of the cleaning tank while applying ultrasonic vibration to the cleaning liquid. After reaching the level of the reduced pressure state, the first time T1 for maintaining the reduced pressure state and the second time T2 for maintaining the recovered pressure state are set such that T2 ≧ T1 . The cleaning liquid to be used is not particularly limited, but a solvent that boils at a low pressure such as a chlorinated solvent is difficult to use, and a hydrocarbon solvent or a water-soluble solvent is preferable. This point is the same in the following inventions.
[0009]
The reduced pressure state is set to a pressure at which the cleaning liquid does not boil, and is specifically determined according to the vapor pressure-liquid temperature characteristic of the cleaning liquid.
[0011]
The cleaning method according to the present invention includes a cleaning tank capable of immersing an object to be cleaned in a cleaning liquid, a pressure reducing mechanism capable of depressurizing the cleaning tank, and a pressure-reducing mechanism capable of instantaneously destroying the reduced pressure state of the cleaning tank. And a bubbling cleaning step that repeats the depressurization state and the return pressure state of the cleaning tank while applying ultrasonic vibration to the cleaning liquid in a state where the object to be cleaned is immersed, and after reaching a predetermined level of depressurization state The first time T1 for maintaining the decompressed state and the second time T2 for maintaining the decompressed state are set such that T2 ≧ T1.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the cleaning apparatus of the present invention will be described in more detail based on examples.
FIG. 1 is a diagram illustrating a cleaning apparatus and a cleaning method according to an embodiment.
[0013]
As shown in this figure, the cleaning apparatus includes a cleaning tank 1 for cleaning an object 7 to be cleaned. The cleaning tank 1 of the present embodiment has a box shape opened upward, and the lid 2 can be opened and closed at the upper opening. Since the lid 2 is closed, the inside of the cleaning tank 1 can be maintained in a sealed state. The cleaning tank 1 has a structure capable of withstanding a reduced pressure of a vacuum level of 1 Toll or less.
[0014]
In the cleaning tank 1 having such a configuration, in order to perform vacuum ultrasonic cleaning, a cleaning liquid 6 is stored inside, and an object to be cleaned 7 is immersed in the cleaning liquid 6. At that time, the cleaning liquid 6 is not put up to the upper end of the cleaning tank 1 but halfway. The type of the cleaning liquid 6 is not particularly limited, but a hydrocarbon solvent that is a flammable liquid can be used.
[0015]
The cleaning tank 1 is provided with an ultrasonic oscillator 9 that applies ultrasonic waves to the cleaning liquid 6 stored in the tank. In the ultrasonic oscillator 9 of the present embodiment, an ultrasonic vibrator having a structure capable of withstanding decompression is provided at the lower portion of the cleaning tank 1.
[0016]
A vacuum pump 8 is connected to the cleaning tank 1 as a pressure reducing mechanism for reducing the pressure in the tank. The vacuum pump 8 is connected to the cleaning tank 1 via the pressure reducing valve 3, and the communication with the cleaning tank 1 is opened and closed by operating the pressure reducing valve 3. The pressure reducing valve 3 is connected to a position above the liquid level of the cleaning tank 1.
[0017]
The cleaning tank 1 is further connected with a return pressure valve 4 that can destroy the reduced pressure in the cleaning tank 1. In this embodiment, the pressure in the cleaning tank 1 is released to the atmospheric pressure by opening the return pressure valve 4. The return pressure valve 4 is connected to a position above the liquid level of the cleaning tank 1.
[0018]
The cleaning tank 1 is provided with a pressure reducing sensor (pressure sensor) 5 for measuring the pressure in the tank and controlling the opening and closing of the pressure reducing valve 3 and the pressure-reducing valve 4 based on the measured pressure. The decompression sensor 5 is provided at a position above the liquid level of the cleaning tank 1. By using the decompression sensor 5, the inside of the tank can be decompressed by the vacuum pump 8 until the pressure of the cleaning tank 1 reaches a predetermined level.
[0019]
Next, a characteristic cleaning method by the cleaning device of the above embodiment will be described by naming it piston cleaning and bubbling cleaning.
[Piston cleaning]
Here, piston cleaning means a cleaning method in which the object to be cleaned is immersed in the cleaning liquid and the pressure reduction state and the pressure-recovery state are repeated a plurality of times, and the object to be cleaned that does not have an open hole vertically above in the immersion state. It is preferably applied to. Hereinafter, the cleaning procedure will be described with reference to FIG.
[0020]
First, the cleaning object 7 is immersed in the cleaning tank 1 in which the cleaning liquid 6 is stored, and the lid 2 of the cleaning tank 1 is covered. Next, the vacuum pump 8 is operated in a state where the pressure-reducing valve 4 is closed and the pressure-reducing valve 3 is opened, and the space above the liquid level in the tank is depressurized. When the pressure in the cleaning tank 1 is reduced in this manner, air is released from the air pocket portion 7a and a similar vacuum is obtained (FIGS. 2A and 2B). To what extent the pressure is reduced is appropriately set. For example, in this embodiment, the pressure in the cleaning tank 1 is reduced to about 60 mmHg (−700 mmHg). The pressure level is grasped by the decompression sensor 5 installed in the cleaning tank 1.
[0021]
When the pressure is reduced to a predetermined level by the pressure reducing sensor 5, the pressure reducing valve 3 is closed and the pressure return valve 4 is opened. Thereby, since the inside of the tank is changed to the atmospheric pressure, the air pocket portion 7a in the object 7 to be cleaned is also decompressed, and thus the cleaning liquid 6 is forced to flow into the air pocket portion 7a (FIG. 2). (C)). The decompression is performed over about 10 seconds, for example, and the decompression is preferably performed all at once in a minute time of about 0.5 seconds, for example. In the present embodiment, the operation of the vacuum pump 8 is continued and the return pressure operation is performed.
[0022]
After that, when the pressure inside the cleaning tank 1 is reduced again by the above-described method, the cleaning liquid 6 that has entered the air pocket 7a escapes from the pocket portion 7a according to the pressure, and becomes the original vacuum space. In the cleaning apparatus of the present invention, the pressure reduction by the vacuum pump 8 and the pressure return by the pressure-reducing valve 4 are repeated alternately over a plurality of times instead of once. Although the number of repetitions is not particularly limited, for example, it is usually performed 3 to 4 times or more.
[0023]
After repeating depressurization and return pressure a plurality of times as described above, the ultrasonic oscillator 9 is operated in an atmospheric pressure state to start ultrasonic cleaning. Of course, ultrasonic cleaning may be performed prior to piston cleaning.
[0024]
According to the piston cleaning of the present embodiment, reliable cleaning can be achieved even if the object to be cleaned 7 has the air pocket 7a. That is, under atmospheric pressure, the air pocket 7a is not in contact with the cleaning liquid 6 as shown in FIG. 2 (a), but when the inside of the tank is depressurized, the air expands as shown in FIG. 2 (b). It escapes from the inside of the pocket 7a, and the space is evacuated. Then, when the inside of the tank is restored, the cleaning liquid is filled in the vacuum air pocket 7a as shown in FIG.
[0025]
Moreover, when the pressure is restored from the vacuum state, a slight amount of air remains even if the pressure is restored by returning the pressure at a stretch in a short time. Almost the entire area in the pocket 7 a is filled with the cleaning liquid 6. Further, the effect of the cleaning liquid 6 at the time of returning pressure to slide and clean the air pocket surface can be expected. In addition, by alternately and repeatedly performing such pressure reduction and return pressure, there is an effect that the cleaning liquid 6 is forcibly and surely permeated into the air pocket portion (a blind hole or a close gap between parts) 7a.
[0026]
In this way, by performing decompression and decompression of the cleaning tank 1, it is possible to clean the portion of the air pocket that the cleaning liquid 6 was not able to contact, and this series of processes is reproducible, so it is operated repeatedly. Thus, there is an effect of washing out foreign matter by taking in and out the cleaning liquid 6 that has entered the air pocket.
[0027]
[Bubbling cleaning]
Next, bubbling cleaning according to the embodiment will be described. Here, bubbling cleaning refers to a cleaning method in which the object to be cleaned is immersed in a cleaning liquid and subjected to ultrasonic vibration while repeating a reduced pressure state and a return pressure state a plurality of times. It is suitably applied to the cleaning of the object to be cleaned. Hereinafter, the cleaning procedure will be described with reference to FIG.
[0028]
The ultrasonic vibration is realized by an ultrasonic vibrator that can withstand the reduced pressure provided in the lower part of the cleaning tank 1. Originally, ultrasonic cleaning is performed by generating vacuum bubbles (cavitation) by ultrasonic vibration generated in the liquid. In other words, the air bubbles tend to break down due to the vacuum, which appears as a cleaning effect.
[0029]
However, when ultrasonic vibration is applied under reduced pressure, the cavitation that occurs almost uniformly turns into bubbles, which widens the gaps between the objects 7 to be cleaned and promotes contact with the cleaning liquid 6. Be expected. In addition, the bubbles remain inflated under reduced pressure. However, when the pressure is restored, the bubbles become smaller and are destroyed. For example, minute bubbles are infiltrated between the plate-like workpieces 7 and 7 that are in close contact with each other. By expanding the bubbles, it is possible to effectively wash by allowing the cleaning liquid 6 to enter while separating the plate-like workpieces 7 from each other. Thus, under the reduced pressure, the original effect of ultrasonic cleaning is lower than the atmospheric pressure state, but a strong effect is expected in the case of a close contact part or a thin plate.
[0030]
FIG. 3 illustrates this relationship. As shown in FIG. 3 (a), under atmospheric pressure, the cleaning liquid 6 does not easily enter the space between the plate-like workpieces 7 and 7 that are in close contact with each other, and it takes time to separate the close contact surface even with ultrasonic waves. I can't expect it. However, as shown in FIG. 5B, when the inside of the tank is depressurized and ultrasonically oscillated, an infinite number of high-density bubbles are generated in the entire liquid, and the gap between the contact surfaces can be widened. Then, it is preferable to periodically repeat such bubbling cleaning under reduced pressure and ultrasonic cleaning performed in a state where the inside of the tank is decompressed as shown in FIG. By repeating the depressurization and the return pressure, as described above, the expansion of the gap between the contact surfaces is more efficiently performed by the expansion action of the microbubbles that have entered the clearance between the contact surfaces. Therefore, as shown in FIG. 2C, the gap between the objects 7 and 7 which are sufficiently released from the close contact is strongly cleaned by the original cavitation effect of the ultrasonic waves.
[0031]
Thus, according to the bubbling cleaning method, the contact surface of the object 7 to be cleaned can be separated by the expansion force of the bubbles, so that the penetration of the cleaning liquid 6 is assisted and a stirring action is also obtained by uniform bubbles. Further, by repeating the depressurization and return pressure under ultrasonic vibration, effective bubbling and original ultrasonic cleaning are alternately applied to the object to be cleaned, and a more accurate cleaning effect can be obtained. In addition, although immersion cleaning may be completed by such bubbling cleaning, as shown in FIG. 3, it may be fixed to an atmospheric pressure state from the middle and may be shifted to normal ultrasonic cleaning. In this case, it is preferable to shift to ultrasonic cleaning after repeating the decompression and the decompression 4 to 5 times.
[0032]
Here, the time required for decompression is normally about 5 seconds, but when the predetermined decompression level is reached, the state is maintained by T1, and after the instantaneous decompression, the decompressed state is maintained by T2, T2 ≧ T1 It is preferable to set to. More preferably, T2 ≧ 2 × T1, typically T1 = about 5 seconds and T2 = about 10 seconds or more.
[0033]
In addition, in order to satisfy the use of vacuum ultrasonic waves, it is necessary to control the pressure in the tank, and the reason is that the boiling point of the cleaning liquid 6 is lowered by reducing the pressure. When the pressure of the vacuum ultrasonic wave is excessively reduced, the cleaning liquid 6 boils, and the ultrasonic vibrator is operated without touching the liquid. Further, the fine and uniform bubbles generated by the ultrasonic waves are hindered by the boiling of the cleaning liquid 6 and a uniform cleaning effect cannot be obtained. Therefore, when using vacuum ultrasonic waves, it is necessary to control the decompression force, and it is necessary to control the pressure (determine the decompression level) according to the vapor pressure-liquid temperature characteristic of the cleaning liquid 6.
[0034]
The cleaning apparatus of the present invention is not limited to the configuration of the above embodiment, and can be changed as appropriate. For example, in the above embodiment, the cleaning of the bag hole (air pocket) part, the close contact part, and the thin plate part has been mainly described. However, the cleaning object 7 applied to the cleaning apparatus of the present invention is not limited to these, and for example, a small diameter. Applicable to various shapes such as pipe parts and porous parts.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to realize a cleaning apparatus and a cleaning method capable of effective cleaning regardless of the shape and the degree of close contact of an object to be cleaned.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating an embodiment of the present invention.
FIG. 2 is a diagram illustrating a cleaning method according to an embodiment.
FIG. 3 is a drawing for explaining another cleaning method according to the embodiment.
[Explanation of symbols]
1 Washing tank 2 Lid 3 Pressure reducing valve 4 Pressure reducing valve 5 Pressure sensor (pressure reducing sensor)
6 Cleaning liquid 7 Object to be cleaned 8 Depressurization mechanism (vacuum pump)
9 Ultrasonic oscillator

Claims (4)

A cleaning tank capable of immersing an object to be cleaned in a cleaning liquid, a decompression mechanism capable of depressurizing the cleaning tank, and a return pressure mechanism capable of instantaneously destroying the decompressed state of the cleaning tank,
In a state where the object to be cleaned is immersed, it operates including a cleaning step that repeats the reduced pressure state and the return pressure state of the cleaning tank while applying ultrasonic vibration to the cleaning liquid,
A cleaning apparatus characterized in that, after reaching a reduced pressure state of a predetermined level, a first time T1 for maintaining the reduced pressure state and a second time T2 for maintaining the recovered pressure state are set to T2 ≧ T1. .   The cleaning apparatus according to claim 1, wherein objects to be cleaned that are in close contact with each other are included in the cleaning target.   A cleaning tank capable of immersing an object to be cleaned in a cleaning liquid, a pressure reducing mechanism capable of depressurizing the cleaning tank, and a pressure-reducing mechanism capable of instantaneously destroying the reduced pressure state of the cleaning tank, and immersing the object to be cleaned In this state, a cleaning step of repeating the pressure reduction state and the pressure recovery state of the cleaning tank while applying ultrasonic vibration to the cleaning liquid is included. After reaching a predetermined level of the pressure reduction state, the first time T1 for maintaining the pressure reduction state And the 2nd time T2 which maintains a return pressure state is the washing | cleaning method set to T2> = T1.   The cleaning method according to claim 3, wherein the objects to be cleaned are in close contact with each other.

Images