JP2929928B2 - Vacuum cleaning method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning technique, and particularly to a technique effective when applied to a cleaning technique for components of a precision device.

[0002]

2. Description of the Related Art In general, components of a precision electric device such as a magnetic disk device are cleaned with high precision in order to prevent an obstacle due to dust adhesion, and are assembled after removing adhering dust. ing.

[0003] Conventionally, this kind of parts has been washed with chlorofluorocarbon, but alternative cleaning methods have been sought from international consent to ban the use of chlorofluorocarbons. For example, JP-A-2-86878
The technology disclosed in Japanese Patent Laid-Open Publication No. H11-216,199, immersed an article by putting a cleaning liquid in a closed container, and rapidly released and increased the pressure after reducing the internal pressure of the container, thereby causing a rapid rise in the liquid level in the container. The surface of the article is cleaned by a high-speed flow of the liquid. In addition, although such a simple vacuum cleaning method has a certain degree of effectiveness in smooth cleaning of articles, it does not penetrate the inside of the holes when cleaning precision articles having bag holes or the like. By repeating pressure reduction and pressure increase (opening to atmosphere) (hereinafter referred to as “pressure swing”), air in the blind hole of precision parts is eliminated, and a detergent is sent into the blind hole using this process to clean the details. Possible ways have been proposed. Also, transfer the detergent to the auxiliary tank after vacuum cleaning, empty the vacuum cleaning tank,
The process of reducing the pressure in the vacuum cleaning tank again to remove residual oil and detergent in the blind hole of the precision part (hereinafter, referred to as liquid removal) is also performed. As such a pressure reducing means for adopting such a washing step, an oil rotary vacuum pump or a water ring type vacuum pump is generally used in order to exhaust air from a pressure reducing tank.

[0004]

However, in the conventional vacuum cleaning, there is a problem in that the detergent remaining in the vacuum tank at the time of vacuum is circulated to the exhaust side connected to the vacuum means. When the detergent goes around, the oil deteriorates in the case of an oil rotary vacuum pump, and in the case of a water ring vacuum pump,
The detergent is mixed in the sealing water. In any case, the vacuum pump cannot perform a predetermined performance, and a problem arises in that the cleaning performance is reduced.

[0005] It is an object of the present invention to prevent the detergent from flowing into the vacuum exhaust side connected to the tank when the pressure in the vacuum tank is reduced during the vacuum cleaning, and to maintain the cleaning performance of the vacuum cleaning at a constant high level. It is in.

[0006]

In order to achieve the above object, a reduced-pressure cleaning method according to the present invention comprises placing an article to be cleaned and a cleaning liquid in a reduced-pressure cleaning tank, and cleaning the article by reducing and increasing the pressure. Cleaning under reduced pressure
Before the main cleaning at a lower vacuum than the reduced vacuum
Preliminary decompression was performed, and at the time of each depressurization including preliminary depressurization, ultrasonic waves were irradiated into the decompression cleaning tank to perform cleaning while suppressing growth of cleaning liquid bubbles.

Further, the ultrasonic waves are irradiated into a reduced-pressure cleaning tank.
Position at least includes the position above the cleaning liquid level.
Configured.

[0008]

[0009]

[0010] The reduced-pressure cleaning apparatus according to the present invention has a reduced-pressure cleaning tank in which a cleaning liquid and an article to be cleaned are put.
A pressure reducing means and an air passage are connected to the reduced pressure cleaning tank via opening / closing valves, respectively .
The reduced pressure cleaning device comprising mounting an ultrasonic oscillator for irradiating ultrasonic waves to the cleaning target object, the vacuum in the cleaning vessel irradiation of ultrasonic waves to a position above the washing liquid surface, in addition to the <br/> ultrasonic oscillator
Mounting an ultrasonic oscillator for by defoaming to morphism, operation of the defoaming ultrasonic oscillator when intracisternal vacuum value reaches the preset value
It was configured so that

[0011]

The present inventor has confirmed that the following method is effective through a study for preventing the detergent from flowing into the exhaust side when the pressure is reduced. In the first method, by irradiating the ultrasonic wave during the depressurization, it is possible to prevent the detergent from flowing into the exhaust side.
Table 1 shows that detergent was placed in a 300 mm diameter stainless steel beaker.
This is the result of measuring the time and growth rate of the detergent foam growing to a height of up to 200 mm when irradiating ultrasonic waves during decompression and when irradiating ultrasonic waves.

[0012]

[Table 1]

As can be understood from the above table, by irradiating the ultrasonic wave during the decompression, the growth rate of the detergent foam can be suppressed to less than half, so that the detergent can be prevented from flowing into the exhaust side. .

According to the second method, by performing preliminary depressurization before performing decompression cleaning, it is possible to prevent the detergent from flowing into the exhaust side. 100-150 before pressure swing or drainage
Preliminary decompression of Torr can eliminate most of the detergent bubbles on the liquid surface of the vacuum cleaning tank, the wall surface of the vacuum cleaning tank, and the surface of the object to be cleaned, thus preventing the detergent from flowing to the exhaust side. .

According to the above-described structure of the present invention based on such knowledge, the growth of bubbles of the cleaning liquid is suppressed by irradiating ultrasonic waves during depressurization, and preliminary depressurization is performed before performing decompression cleaning. This makes it possible to eliminate bubbles adhering to the inner wall surface of the reduced-pressure cleaning tank, thereby preventing the detergent from flowing from the inside of the reduced-pressure cleaning tank to the exhaust side. Thereby, the cleaning performance of the reduced pressure cleaning can be kept constant and high.

[0016]

FIG. 1 is a piping diagram of a reduced pressure cleaning apparatus according to one embodiment of the present invention. The reduced-pressure cleaning tank 10 has a cleaning ultrasonic vibrator 12 provided on the bottom surface thereof, and has another bubble-eliminating ultrasonic vibration different from the cleaning ultrasonic vibrator 12 on the side wall surface. The child 14 is attached. The reduced-pressure cleaning tank 10 is connected to an auxiliary tank 16 for replacing the cleaning liquid supplied to the inside, and the replacement of the cleaning liquid is caused to flow by opening a discharge valve 20 provided in a discharge line 18. The cleaning liquid is returned to the cleaning tank 10 via the pump 26 and the filter 28 by opening the liquid supply valve 24 provided in the liquid supply pipe 22 to perform the cleaning.

A vacuum pump 30 as a decompression means for exhausting air from the inside of the tank is provided at an upper position of the reduced pressure washing tank 10.
Is connected via an exhaust valve 32, and an atmosphere opening pipe 34 for increasing the pressure by opening the depressurized tank to the atmosphere is also connected via an opening valve 36. Further, a pressure sensor 38 for monitoring the internal pressure of the reduced pressure washing tank 10 is provided. The vacuum cleaning tank 1
0 can be sealed by the lid 40 as a matter of course. Further, the auxiliary tank 16 is provided with a heater 42 for heating the removed cleaning liquid to a predetermined temperature (for example, about 40 ° C.).

An article washing process performed by the reduced pressure washing apparatus will be described with reference to FIG. First, FIG.
As shown in (1), the articles 4 to be cleaned are stored in the reduced-pressure cleaning tank 10.
4 is introduced by a transporting means (not shown), and a detergent liquid diluted to a concentration of 5 to 10% by diluting a stock solution of a surfactant into a tank is supplied by heating the cleaning liquid to a temperature of 30 to 50 ° C. by a heating means. After injecting the cleaning solution and before starting the main cleaning,
As shown in FIG. 2 (2), preliminary pressure reduction is performed. This is because the lid 40 is closed and the cleaning liquid discharge valve 2 is closed.
0, the liquid supply valve 24 and the release valve 36 are closed, the exhaust valve 32 is opened, and the vacuum pump 30 is driven.
Reduce the pressure to 150 Torr. Pressure sensor 38 is 10
When the pressure becomes 0 to 150 Torr, as shown in FIG. 2C, the exhaust valve 32 is closed, the opening valve 36 is opened, and the reduced-pressure cleaning tank 10 is returned to the atmospheric pressure.

Thereafter, the cleaning process is started. This is repeated while controlling the opening and closing of the open valve 36 and the exhaust valve 32 by the pressure sensor 38, and as shown in FIG.
Since the pressure is reduced to 50 Torr for a certain period of time, the exhaust valve 32 is closed, the release valve 36 is opened, and the pressure-reducing cleaning tank 1 is returned to the atmospheric pressure a plurality of times. is there.

After the main cleaning is completed, as shown in FIG. 2 (5), the discharge valve 20 is opened and the cleaning liquid in the reduced pressure cleaning tank 10 is transferred to the auxiliary tank 16 by gravity drop, and the reduced pressure cleaning is performed. When the washing liquid having a height of about 2 cm remains in the tank 10, the discharge valve 20 is closed (FIG. 2 (6)). And reduced pressure washing tank 1
0 is reduced to the value at the time of the main washing in the same manner as above, and at the same time, the defoaming ultrasonic vibrator 14 is actuated to perform the dewatering treatment (FIG. 2 (7)).

On the other hand, in the auxiliary tank 16, the heater 42 is operated to heat the cleaning liquid during the liquid removal, and the temperature of the cleaning liquid is adjusted to a temperature suitable for cleaning (FIG. 2 (8)). After completion of the liquid removal, the reduced-pressure cleaning tank 10 is returned to the atmospheric pressure, the liquid supply valve 24 is opened, and the cleaning liquid in the auxiliary tank 16 is transferred by the pump 26 (FIG. 2).
(9)). At this time, the cleaning liquid is filtered by the filter 28 and supplied to the reduced-pressure cleaning tank 10 in a clean state. Therefore, the cleaning liquid in the reduced-pressure cleaning tank 10 is cleaned for each cleaning. Such a series of operations is performed under the control of a sequence program defined by the controller 46.

During the series of cleaning operations, including the pre-depressurization, the ultrasonic vibrator 12 and the bubble elimination ultrasonic vibrator 14 installed in the cleaning tank 10 are operated during the depressurizing operation to apply ultrasonic waves to the cleaning tank 10. By irradiating, the growth rate of the bubbles of the cleaning liquid can be controlled, and therefore, the cleaning liquid can be prevented from flowing into the exhaust side.

[0023]

As described above, according to the present invention,
Preliminary depressurization is performed prior to the main cleaning to eliminate bubbles of the cleaning liquid adhering to the inner wall of the tank.During depressurization, the growth of bubbles can be suppressed by an ultrasonic vibrator, Since the growth of bubbles that reach the exhaust side can be suppressed even during the operation, it is possible to prevent the trouble due to the bubbles of the cleaning liquid that hinders the operation of the decompression means during the decompression cleaning operation by the pressure swing, and to perform the decompression cleaning. An excellent effect that the cleaning performance can be kept constant high can be obtained.

[Brief description of the drawings]

FIG. 1 is a piping system diagram of a reduced pressure cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is a process explanatory view of a reduced pressure cleaning method according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Decompression washing tank 12 Ultrasonic oscillator for cleaning 14 Ultrasonic oscillator for bubble elimination 16 Auxiliary tank 18 Discharge line 20 Discharge valve 22 Liquid supply line 24 Liquid supply valve 26 Pump 28 Filter 30 Vacuum pump 32 Exhaust valve 34 Atmosphere Opening line 36 Opening valve 38 Pressure sensor 40 Lid 42 Heater 44 Article to be cleaned 46 Controller

Continuation of the front page (56) References JP-A-3-30329 (JP, A) JP-A-5-269446 (JP, A) JP-A-63-10531 (JP, A) JP-A-56-24081 (JP, A) JP-A-7-136604 (JP, A) JP-A-5-269446 (JP, A) JP-A-5-169039 (JP, A) JP-A-6-296940 (JP, A) 5-212360 (JP, A) JP-A-4-58527 (JP, A) JP-A-2-23620 (JP, A) JP-A-61-178185 (JP, U) JP-A-5-71766 (JP, A) U) JP 32 9843 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB name) B08B 1/00-11/04 H01L 21/304 341

Claims (3)

(57) [Claims] In a reduced-pressure cleaning method in which an article to be cleaned and a cleaning liquid are placed in a reduced-pressure cleaning tank and the article is cleaned by reducing and increasing the pressure, a reduction in the main cleaning is performed before performing the reduced-pressure cleaning.
Preliminary depressurization at a lower vacuum than the pressure
A vacuum cleaning method comprising irradiating an ultrasonic wave into the vacuum cleaning tank at each pressure reduction including a preliminary pressure reduction to perform cleaning while suppressing growth of bubbles in the cleaning liquid. 2. A position for irradiating the ultrasonic wave into a reduced-pressure cleaning tank.
Is characterized by including at least a position above the cleaning liquid level.
The reduced pressure cleaning method according to claim 1 . 3. A reduction in the amount of washing liquid and articles to be washed.
It has a pressure washing tank.
Each air passage is connected via an open / close valve
Ultrasonic irradiation of the object to be cleaned in the cleaning liquid
In a reduced-pressure cleaning device equipped with a sonic oscillator,
In addition to the ultrasonic oscillator, the vacuum cleaning tank
Attaching ultrasonic vibrator to irradiate ultrasonic wave to one side
When the decompression value in the tank reaches the set value,
Characterized in that the ultrasonic oscillator is operated.
Pressure washer.