JP2018083155A - Vacuum degreasing and washing apparatus and washing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To replace greases on a portion of a complex shape having upward, downward and bottomed deep holes and a complex shape having a closed part by making supply of washing liquid with respect to such complex shapes possible.SOLUTION: A vacuum degreasing and washing apparatus 1 includes: a washing chamber 2 which has an air-tight sealed structure and can heat the interior; a washing liquid tank 3 which warms and retains washing liquid; a nozzle 7 which injects pre-warmed washing liquid to the interior of the washing chamber 2; an opening/closing valve V4 for sending out inactive gas to the washing chamber 2; a vacuum pump 9 which turns the interior of the washing chamber 2 into a vacuum state; and a controller 10. A pressure reduction process of preliminarily heating washing liquid to a temperature just below a predetermined temperature at which the washing liquid is boiled at a prescribed degree of vacuum, reducing pressure of the washing chamber 2 up to the predetermined vacuum state and heating an interior temperature to a predetermined temperature or more is executed and a pressure recovery process of blowing out the heated washing liquid to the interior of the washing chamber in which the pressure reduction process is completed and elevating the interior pressure in the washing chamber by means of washing liquid and inactive gas is executed. Further, the pressure reduction process and the pressure recovery process are repeated two times or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vacuum degreasing and cleaning apparatus used for degreasing and cleaning machine parts and the like, and a cleaning method therefor.

As a technique for degreasing and cleaning machine parts and the like, there are known a method of cleaning an object to be processed by immersing it in a cleaning liquid and a method of cleaning with a vapor of the cleaning liquid. Thus, there exists a technique shown by patent document 1 as a technique, for example. Further, as a technique for making the cleaning chamber have a negative pressure, cleaning with the cleaning liquid vapor and showering, and finally evacuating and drying, there is one disclosed in Patent Document 2, for example. Further, for example, Patent Document 3 discloses a technique in which cleaning liquid staying in a cleaning chamber is circulated and used again for shower cleaning when cleaning with steam and shower.

JP-A-2-198678 JP-A-3-101881 Japanese Patent Laid-Open No. 11-47705

Since cleaning with steam causes vapor to adhere to the object to be processed and condensate, the object to be processed may be a concave or convex part with a concave shape facing upwards and downwards, with a deep hole with a bottom. Steam can get into. However, the oil accumulated in the concave shape and deep hole portion has almost the same specific gravity as the cleaning liquid and the oil to be cleaned, so that it cannot be replaced with the cleaning liquid and is difficult to clean. In addition, especially in complicated shapes, if there is a place where the planar shape is in close contact with the object to be processed or a closed part (detail) such as a screw part to which a bolt is attached, the place does not communicate with the outside. Cleaning is extremely difficult because no replacement is performed with the cleaning liquid and no replacement (cleaning) is performed.
The present invention enables supply of a cleaning liquid to a concave shape having an upward and downward direction, a complicated shape having a deep hole with a bottom, and a complicated shape having a closed portion, and by replacing the oils and fats at these parts with the cleaning liquid. It makes it possible to remove the adhered oil.

The cleaning method of the present invention includes a pressure reducing step for reducing the pressure in a cleaning chamber having an airtight and sealed structure to a predetermined vacuum state,
A return pressure step of increasing the pressure in the cleaning chamber with a shower of cleaning liquid and an inert gas;
The decompression step and the decompression step are repeated twice or more in order.

Further, the vacuum degreasing cleaning apparatus of the present invention has an airtight and sealed structure, and a cleaning chamber capable of heating the interior,
A cleaning solution tank that holds the cleaning solution by heating;
A nozzle for injecting the heated cleaning liquid into the cleaning chamber;
A vacuum pump that evacuates the cleaning chamber;
An on-off valve for delivering an inert gas to the cleaning chamber;
A controller,
The controller is
The cleaning chamber is depressurized to a predetermined vacuum state by the vacuum pump, and the depressurization step for controlling the cleaning chamber so as to heat the room temperature to a temperature higher than the temperature at which the cleaning liquid boils at the vacuum degree and the cleaning liquid boil at the vacuum degree in advance. Controlling the cleaning liquid tank to heat to a temperature immediately below the temperature to be
A pressure-reducing step in which the cleaning liquid heated by controlling the nozzle is ejected into the chamber of the cleaning chamber after the depressurization step, and the pressure in the cleaning chamber is increased by the cleaning liquid and the inert gas;
The decompression step and the decompression step are repeated twice or more.

According to the present invention, the oil and fat is drawn out from the blockage portion due to the pressure difference by the pressure reduction process and replaced with the cleaning liquid staying on the surface on the outer surface of the object to be processed, and then the cleaning liquid is blocked by the pressure recovery process. By diluting the oil and fat inside the closed part by being drawn into the part and repeating the decompression process and the return pressure process, it becomes a complicated shape with a concave shape facing upwards, a deep hole with a bottom, and a complicated shape with a closed part. The attached oil and fat can be removed.

It is a block diagram of the vacuum degreasing cleaning apparatus by embodiment of this invention. It is a figure for demonstrating the cleaning method of a vacuum degreasing cleaning apparatus.

In recent years, cleaning liquids used in industrial cleaning include hydrocarbon-based cleaning liquids, water-based cleaning liquids, organic solvent-based cleaning liquids, and the like. Hydrocarbon cleaning liquids are widely used because of their high detergency and environmental considerations. The hydrocarbon-based cleaning liquid is a compound composed only of carbon and hydrogen, and can be recycled by distillation regeneration.

In general, using hydrocarbon-based cleaning liquid in a tank that is heated and maintained under reduced pressure when removing oil and fat adhering to the object to be processed in a hydrocarbon-based cleaning device, it is cleaned by shower, steam, immersion, etc. Replaces oils and fats adhering to the product with a cleaning solution. Next, when the pressure in the tank is reduced, the substituted cleaning liquid remaining in the object to be processed exceeds the boiling point due to the reduced pressure, evaporates, the object to be processed becomes dry, and the cleaning is completed.

In the present invention, a hydrocarbon-based cleaning liquid having a boiling point lower than that of oil (eg, heavy oil) adhering to an object to be degreased and cleaned is used in an environment (temperature and pressure) exceeding the boiling condition of the hydrocarbon-based cleaning liquid. By introducing a hydrocarbon cleaning liquid just under boiling conditions into the tank placed in the tank, the cleaning chamber is instantly saturated and maintained. As the hydrocarbon cleaning liquid, it is desirable to use a light hydrocarbon cleaning liquid containing a light component (= substance having a low boiling point). Hereinafter, the hydrocarbon-based cleaning liquid is simply referred to as “cleaning liquid”.

Further, in the present invention, after the oil and fat adhering to the object to be cleaned is replaced with the cleaning liquid by shower, steam, immersion, or the like, the cycle of decompression and re-pressure is repeated in the cleaning chamber. In depressurization, the oil and fat existing in the closed portion of the object to be processed is drawn to the surface of the object to be processed, and the pressure in the cleaning chamber is restored by supplying the cleaning liquid and the inert gas that are vaporized to the cleaning chamber. The cleaning liquid is drawn into a closed portion where there is no communication of the cleaning liquid. By repeating this, the oil adhering in the closed portion is replaced with the cleaning liquid. Then, the cleaning liquid is heated and evaporated under reduced pressure to remove oil from the processed product.

A vacuum degreasing and cleaning apparatus 1 according to an embodiment of the present invention will be described. In FIG. 1, a vacuum degreasing and cleaning apparatus 1 includes an airtight and sealed structure cleaning chamber 2, a cleaning liquid tank 3, a regenerator 4, a septic tank 5, a steam generator 6, various pumps, various on-off valves, and a controller for controlling these. 10

The cleaning chamber 2 is provided with an on-off valve V3 for cleaning liquid shower and an on-off valve V5 for cleaning liquid vapor. On-off valves V6 and V7 for discharging the cleaning liquid staying at the bottom of the cleaning chamber 2 and the chamber of the cleaning chamber 2 are exhausted. An on-off valve V2 is provided. The cleaning liquid that has passed through the on-off valve V <b> 3 is sprayed from nozzles 7 that are disposed at various locations in the cleaning chamber 2. Further, the cleaning chamber 2 is provided with a heating pipe H1 that performs indirect heating with a heat medium oil that heats the cleaning agent staying in the chamber and promotes the generation of heated steam. The cleaning chamber 2 further includes a pressure detector S1, a vacuum gauge A1, and liquid level detectors R1-R3. Nitrogen gas was used as the inert gas.

The cleaning liquid tank 3 has an on-off valve V9, holds the cleaning liquid regenerated by the regenerating device 4, and an indirect heating pipe H2 made of heat medium oil is provided in the tank. The septic tank 5 temporarily holds the cleaning liquid discharged from the cleaning chamber via the on-off valve V6, and sends it to the regenerator 4 as needed by the pump P1 asynchronously with the cleaning by the vacuum degreasing cleaning apparatus 1. The steam generator 6 vaporizes the cleaning liquid from the on-off valve V8 and sends it into the cleaning chamber 2 through the on-off valve V5. The pump P2 sends the cleaning liquid from the on-off valve V7 or the on-off valve V9 to the pipelines that reach the on-off valve V3 and the on-off valve V8.

The condenser 8 receives the exhaust from the cleaning chamber 2 via the exhaust on-off valve V2, condenses the cleaning liquid contained in the exhaust, and returns it to the cleaning liquid tank 3 via the on-off valve V1 (in this figure, this return line) Was omitted). The vacuum pump 9 is disposed downstream of the condenser 8 and discharges the remaining exhaust gas condensed with the cleaning liquid to the atmosphere.

A cleaning method using the vacuum degreasing cleaning apparatus 1 will be described with reference to FIGS.
In the description, as an example of a machine part having a closed portion such as a complicated shape such as a deep hole with a bottom, a deep hole with a bottom, a close contact portion with a flat shape, a bolt attachment portion, or the like, a cylindrical base body w1 is used. 2 shows a workpiece W in which a bolt hole bn is provided and a bolt w2 is screwed into a fastening shape. It is assumed that the workpiece W has oil and fat (indicated by oblique line segments) attached to the base surface of the base w1 and the head surface of the bolt w2 exposed from the base w1 and the bolt hole bn.

The workpiece W is set in a dedicated jig or a general-purpose jig and is carried into the chamber of the cleaning chamber 2 and set so as not to be immersed in the cleaning liquid, and the cleaning chamber is sealed. Thereafter, the controller 10 starts the cleaning process.

First, normal cleaning is started (STEP 1). Normal cleaning may be performed by immersion, shower, or steam, but the case of cleaning by shower shown in Patent Document 3 will be described. The inside of the cleaning chamber 2 is evacuated by the vacuum pump 9 via the exhaust opening / closing valve V2 and decompressed. The on-off valve V9 is opened. After confirming that the predetermined vacuum level in the cleaning chamber 2 has been reached by the vacuum gauge A1 in the cleaning chamber 2, the cleaning liquid heated by the heating pipe H2 in the cleaning liquid tank 3 passes through the on-off valve V3 when the pump P2 is started. Injected from the nozzle 7 in a high-pressure shower state. The on-off valves V6 and V7 at the bottom of the cleaning chamber 2 are in a closed state, and the cleaning liquid sprayed by the shower stays in the cleaning chamber 2, and at the same time, is reheated by the heating pipe H1 and is filled with heated steam.

After confirming that the liquid level has risen to a predetermined level by the liquid level detectors R1-R3, the on-off valve V9 is closed, the supply of the cleaning liquid from the cleaning liquid tank 3 is stopped, and the on-off valve V7 is opened for cleaning. The cleaning liquid staying in the lower part of the chamber 2 is ejected from the nozzle 7. This is continued for a specified time, and normal cleaning ends. The pump P2 is stopped, the on-off valve V6 is opened, the on-off valve V3 is closed, the inert gas on-off valve V4 is opened, and the inert gas is introduced into the cleaning chamber 2, thereby cleaning the cleaning liquid remaining in the cleaning chamber 2. Collect in the septic tank 5. The to-be-processed object W is the state from which the fats and oils adhering to the base | substrate w1 and the head surface of the volt | bolt w2 exposed from the base | substrate w1 were removed. Instead of or in addition to cleaning with a shower, cleaning with steam may be performed. In this case, the cleaning liquid is vaporized by the steam generator 6.

Next, a cleaning process is performed for the concave shape upward and downward, the bottomed deep hole, or the closed portion. This cleaning process is performed by repeating the two steps of decompression and decompression as one set in order.

In the decompression step (STEP 2), the on-off valve V2 is opened, the on-off valves V3, V4, V5, V6, V7 are closed, and the pressure in the cleaning chamber 2 is reduced to a predetermined vacuum state (high vacuum). . This lowers the temperature at which the cleaning liquid boils. Furthermore, the room is adjusted to a temperature exceeding the boiling point temperature at which the cleaning liquid boils at that degree of vacuum. By depressurizing the interior of the cleaning chamber 2, the closed portion that has not been conventionally communicated is also depressurized due to the details, and a pressure difference is generated to draw out the gas. At the same time, the oil that is the object to be cleaned inside is also drawn out to the surface of the workpiece W. The to-be-processed object W is the state by which the fats and oils were pulled out by the base | substrate w1 and the head surface of the volt | bolt w2 exposed from the base | substrate w1. The on-off valve V2 is closed and the vacuum pump 9 is stopped.

At an appropriate time before the next re-pressure step (STEP 3), in the cleaning liquid tank 3, the heating pipe H2 is used to bring the cleaning liquid to a temperature just below the boiling point where the cleaning liquid boils in the vacuum degree set in the cleaning chamber 2 by reducing the pressure of STEP 3. Warm the cleaning solution.

In the return pressure step (STEP 3), the cleaning liquid is sprayed from the nozzle 7 by opening the on-off valve V3 via the on-off valve V9 and the pump P2. Thereafter, the on-off valve V4 is opened and the inert gas is supplied at different times. The reason for shifting the time is to first promote the vaporization of the cleaning liquid. Since the interior of the chamber is depressurized and heated by the operation of the previous depressurization step (STEP 2), the cleaning liquid heated immediately below the boiling point is boiled at the same time as being introduced into the chamber under a high depressurization (vacuum) and becomes steam. Instantly becomes saturated vapor. This saturated vapor is cooled and liquefied on the surface of the workpiece W, and the oil and fat extracted in the decompression step (STEP 2) is diluted and washed and stays on the surface of the workpiece W.

After that, by supplying an inert gas from the on-off valve V4 together with a shower of the cleaning liquid supplied into the cleaning chamber 2, the pressure in the cleaning chamber 2 is increased by the vapor of the cleaning liquid and the inert gas, and the pressure is restored. . Of the cleaning liquid supplied into the cleaning chamber 2, the liquid cleaning liquid cleans away the oil and fat remaining on the surface of the workpiece W. By returning the pressure in the cleaning chamber 2, a differential pressure is generated between the indoor atmosphere and the closed portion of the workpiece W, and the cleaning liquid staying on the surface of the workpiece W is drawn into the closed portion. Thereby, the oil and fat adhering to the closed portion of the workpiece W is diluted with the drawn cleaning liquid. The oil and fat adhering to the surface of the substrate w1 of the workpiece W and the oil and fat adhering to the head surface of the bolt w2 exposed from the substrate w1 are washed away by the cleaning liquid.

Next, returning to the pressure reduction step (STEP 2), the pressure inside the cleaning chamber 2 is reduced again. As a result, the oil and fat diluted with the cleaning liquid drawn in the previous pressure-recovery step (STEP 3) is drawn out to the outer surface of the workpiece W by a pressure difference. When the oil in the closed portion is sufficiently drawn out, next, the return pressure step (STEP 3) is performed. In this process, the washing liquid saturation state is regenerated again by showering and steam, and the oil and fat drawn out by being supplied to the surface of the cleaning product is cleaned (replaced). Then, the pressure in the cleaning chamber 2 is restored by resupplying the steam and the inert gas. As the pressure in the cleaning chamber 2 increases, the cleaning liquid is again drawn into the details of the cleaning product and further dilutes the oil and fat in the closed portion.

By repeating this process an arbitrary number of times (the number of loops N, N is a natural number of 2 or more), the oils and fats adhering to the details of the cleaning product are replaced with the cleaning liquid, and the cleaning is completed. Next, in the drying step (STEP 4), after the cleaning liquid staying at the bottom of the cleaning chamber 2 is transferred to the septic tank 5, the inside of the cleaning chamber 2 is evacuated. By this operation, the low boiling point cleaning liquid evaporates and the cleaning liquid adhering to the workpiece is evaporated and dried. The evaporated cleaning liquid is liquefied again by the condenser 8 installed between the cleaning chamber 2 and the vacuum pump 9 and collected in the cleaning liquid tank 3.

The number N of loops for repeating the decompression step (STEP 2) and the return pressure step (STEP 3) is preferably determined in advance in consideration of conditions such as the shape of machine parts and attached oil and fat. According to the present embodiment, each time the decompression step (STEP 2) and the decompression step (STEP 3) are repeated, the oil and fat is drawn out from the blockage portion due to the pressure difference, and the cleaning liquid staying on the surface on the outer surface of the workpiece After the replacement, the cleaning liquid is drawn into the closed portion of the object to be processed by the return pressure, and the oil and fat inside the closed portion can be diluted.

In the above embodiment, when the cleaning liquid used in the return pressure step (STEP 3) accumulates at the bottom of the cleaning chamber 2, the predetermined level is set so that the workpiece is not immersed during the return pressure step (STEP 3). The on-off valve V6 is opened so as not to exceed, and is transferred to the septic tank 5. Alternatively, as shown in Patent Document 3, the on-off valve V9 is closed, the supply of the cleaning liquid from the cleaning liquid tank 3 is stopped, and the on-off valve V7 is opened to remove the cleaning liquid retained in the lower part of the cleaning chamber 2 You may be in the endless shower state which injects from 7.

In the above embodiment, in the return pressure step (STEP 3), the cleaning with the cleaning liquid and the return pressure with the cleaning liquid (vapour) and inert gas were performed in parallel. It is possible to perform cleaning with a cleaning liquid that has been filled with steam but has not been vaporized, and then stop the injection of the cleaning liquid from the nozzle 7, open the on-off valve V5, and increase the pressure in the cleaning chamber 2 with an inert gas. .

DESCRIPTION OF SYMBOLS 1 Vacuum degreasing cleaning apparatus 2 Cleaning chamber 3 Cleaning liquid tank 4 Regenerating apparatus 5 Soil tank 6 Steam generator 7 Nozzle 8 Capacitor 9 Vacuum pump 10 Controller A1 Vacuum gauge bn Bolt hole R1-3 Liquid level detector H1, Heating pipe N Inert gas V1-9 On-off valve W Processed object w1 Base w2 Bolt

The cleaning method of the present invention includes a pressure reducing step for reducing the pressure in a cleaning chamber having an airtight and sealed structure to a predetermined vacuum state, and heating the chamber temperature to a temperature equal to or higher than a temperature at which the cleaning liquid boils at the degree of vacuum.
Preliminarily heating the cleaning liquid to a temperature immediately below the boiling temperature at the degree of vacuum;
The heated cleaning liquid is instantaneously boiled by being spouted into the cleaning chamber where the depressurization step is completed,
A return pressure step for increasing the pressure in the cleaning chamber with the cleaning liquid and the inert gas;
The depressurization step and the decompression step are repeated twice or more .

Claims (4)

A depressurization step for depressurizing the interior of the cleaning chamber having an airtight and sealed structure to a predetermined vacuum state;
A return pressure step of increasing the pressure in the cleaning chamber with a shower of cleaning liquid and an inert gas;
A cleaning method, wherein the pressure reduction step and the pressure reduction step are repeated twice or more in order. A depressurization step of reducing the pressure in the cleaning chamber having an airtight and sealed structure to a predetermined vacuum state and heating the chamber temperature to a temperature equal to or higher than a temperature at which the cleaning liquid boils at the degree of vacuum.
Preliminarily heating the cleaning liquid to a temperature immediately below the boiling temperature at the degree of vacuum;
The heated cleaning liquid is instantaneously boiled by being spouted into the cleaning chamber where the depressurization step is completed,
A return pressure step for increasing the pressure in the cleaning chamber with the cleaning liquid and the inert gas;
A cleaning method, wherein the decompression step and the decompression step are repeated twice or more. 3. The cleaning method according to claim 1, wherein the cleaning liquid is a light hydrocarbon-based cleaning liquid, and is for cleaning heavy oil adhering to an object to be processed. A cleaning room that has an airtight and sealed structure and can be heated.
A cleaning solution tank that holds the cleaning solution by heating;
A nozzle for injecting the heated cleaning liquid into the cleaning chamber;
A vacuum pump that evacuates the cleaning chamber;
An on-off valve for delivering an inert gas to the cleaning chamber;
A controller,
The controller is
The cleaning chamber is depressurized to a predetermined vacuum state by the vacuum pump, and the depressurization step for controlling the cleaning chamber so as to heat the room temperature to a temperature higher than the temperature at which the cleaning liquid boils at the vacuum degree and the cleaning liquid boil at the vacuum degree in advance. Controlling the cleaning liquid tank to heat to a temperature immediately below the temperature to be
A pressure-reducing step in which the cleaning liquid heated by controlling the nozzle is ejected into the chamber of the cleaning chamber after the depressurization step, and the pressure in the cleaning chamber is increased by the cleaning liquid and the inert gas;
A vacuum degreasing and cleaning apparatus, wherein the depressurization step and the decompression step are repeated twice or more.