JPH0419320B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an outgoing pipe for extracting the paint liquid in the electrodeposition tank and transferring it to the replacement tank, and a return pipe for returning the paint liquid in the replacement tank to the electrodeposition tank. The present invention relates to an electrodeposition coating device in which a pipe is connected to a paint liquid circulation system piping.

[Conventional technology]

In electrodeposition coating equipment, the paint liquid in the electrodeposition tank is cleaned in order to periodically clean the tank and perform maintenance and inspection work on the electrodes installed in the tank, the paint stirring device, etc. Take it out of the tank and transfer it to the replacement tank,
After cleaning and maintenance and inspection of the electrodeposition tank are completed, the paint liquid in the replacement tank is returned to the electrodeposition tank (see Japanese Patent Application Laid-Open No. 1987-19979).

FIG. 2 is a flow sheet diagram schematically showing such a conventional electrodeposition coating apparatus.

In the figure, 1 is an electrodeposition tank consisting of a tank body 2 and a sub-tank 3, and 4 is a paint liquid circulation system piping in which a circulation pump 5 is interposed to pump the paint liquid in the sub-tank 3 into the tank body 2. The paint liquid overflowing from the tank body 2 into the sub-tank 3 is circulated back into the tank body 2 through the paint liquid circulation system piping 4.

The paint liquid circulation system piping 4 is provided with a filter 6 and a heat exchanger 7 on the discharge side of the circulation pump 5, and a drain pipe 8 for drawing out the paint liquid in the tank body 2 on the suction side of the circulation pump 5. It is connected.

Further, the paint liquid circulation system piping 4 includes an outgoing pipe 10 for transferring the paint liquid extracted from the electrodeposition tank 1 through the pipe 4 and the drain pipe 8 to the replacement tank 9, and a pipe 10 for transferring the paint liquid in the replacement tank 9. Return tube 11 that returns the liquid to the electrodeposition bath 1
is connected.

The outgoing pipe 10 is connected to the paint liquid circulation system piping 4 on the suction side of the circulation pump 5, and the displacement pump 12 installed in the outgoing pipe 10 connects the tank main body 2 and the sub tank 3.
The paint liquid in the tank is simultaneously sucked and pumped into the replacement tank 9.

The return pipe 11 is connected to the paint liquid circulation system piping 4 on the discharge side of the circulation pump 5, and the pump 13 installed in the return pipe 11 sucks the paint liquid in the displacement tank 9, and circulates the paint liquid. It is configured to be returned into the tank body 2 through the system piping 4.

In addition, a replacement paint liquid circulation system piping 14 is connected to the return pipe 11 on the discharge side of the pump 13.
4 and return pipe 11, respectively, are valves 15 and 16.
By this switching operation, the paint liquid stored in the displacement tank 9 is circulated again through the pipe 14 on the path to which it is injected from the riser pipe 17 in the displacement tank 9, and is constantly stirred.

Therefore, under normal conditions, the paint liquid that overflows from the tank body 2 of the electrodeposition bath 1 into the sub-tank 3 is circulated through the paint liquid circulation system piping 4 and is again injected from the riser pipe 18 in the tank body 2. This prevents paint from settling, which can cause poor coating.

When cleaning or maintenance inspection is performed inside the electrodeposition tank 1, the paint liquid is extracted from the tank body 2 and sub-tank 3 by the displacement pump 12 installed in the outgoing pipe 10 and transferred to the displacement tank 9. exchange.

Further, by circulating the paint liquid transferred to the replacement tank 9 through the replacement paint liquid circulation system piping 14, it is constantly stirred and precipitation of the paint in the replacement tank 9 is prevented.

When the cleaning work and maintenance inspection work in the electrodeposition tank 1 is completed, the paint liquid in the replacement tank 9 is returned to the tank body 2 of the electrodeposition tank 1 from the return pipe 11 through the paint liquid circulation system piping 4. Pure water serving as cleaning water is supplied from the water supply pipe 19 into the empty replacement tank 9 to clean the inside of the replacement tank 9.

At this time, the cleaning water supplied into the displacement tank 9 is circulated by the pump 13 through the paint liquid circulation pipe 14, thereby cleaning not only the displacement tank 9 but also the inside of the riser pipe 17 provided in the tank. be done.

[Problem that the invention seeks to solve]

However, in this case, although the inside of the displacement tank 9, the displacement paint liquid circulation pipe 14, and the riser pipe 17 are thoroughly cleaned, the inside of the outgoing pipe 10 cannot be cleaned.
There is also a problem that the inside of the return pipe 11 is not effectively cleaned.

Furthermore, it has been difficult to dispose of the used washing water used for washing the inside of the replacement tank 9.

In other words, one possible method for the used cleaning water containing paint is to return it from the return pipe 11 to the tank body 2 of the electrodeposition tank 1 through the paint liquid circulation system piping 4; Meanwhile, the water level in the electrodeposition tank 1 rises by the amount of cleaning water supplied. When the water level of the sub-tank 3 that overflows the paint liquid from the tank body 2 reaches the same height as the water level of the tank body 2 and rises further, the water level of the tank body 2 that immerses the object to be coated rises and the water level of the tank body 2 rises. In such a case, the used cleaning water cannot be returned to the electrodeposition tank 1 because the liquid level in the electrodeposition tank 2 cannot be controlled.

For this reason, the inventor stopped supplying pure water to the electrodeposition tank 1 from about 1 week to 10 days before the scheduled cleaning and maintenance inspection date in the electrodeposition tank 1, and
Gradually lower the water level inside than normal,
An attempt was made to prevent the water level of the tank body 2 from rising by receiving the increased water when used washing water is returned into the electrodeposition tank 1 into the sub-tank 3 whose water level has decreased.

However, in this case, as the scheduled date approaches, the head of the paint liquid flowing down from the tank body 2 into the sub-tank 3 becomes abnormally large, and the amount of bubbles generated in the sub-tank 3 increases significantly. Since this paint liquid containing a large amount of bubbles is sent to the tank body 2 through the paint liquid circulation system piping 4,
Painting defects occur due to the adhesion of bubbles on the surface of the object to be coated immersed in the tank body 2.

In addition, as another means to avoid such damage, a relay tank (not shown) is provided between the substitution tank 9 and the electrodeposition tank 1 to temporarily store the used washing water. A method of returning washing water from the tank to the electrodeposition tank 1 in small amounts over a long period of time can be considered, but in this case, extra equipment is required and the equipment cost increases, and at the same time, the washing water is returned little by little over a long period of time. The disadvantage is that the work is cumbersome.

In addition, in order to reliably prevent the water level from rising in the electrodeposition bath 1 as described above and to shorten the time required for returning the wash water in the relay tank to the electrodeposition bath 1 as much as possible, it is necessary to replace the water from the water supply pipe 19. Although it is necessary to reduce the amount of washing water supplied to the tank 9 as much as possible, in this case, there is a problem that the inside of the replacement tank 9 and the like cannot be sufficiently washed.

Note that if all used washing water is treated as waste water without returning it to the electrodeposition tank 1, the problem of rising water level in the electrodeposition tank 1 will not occur and there will be no need to install an extra relay tank. In this case, a large amount of the paint contained in the wash water must be discarded together with the wash water, resulting in wasted paint.

Therefore, the present invention is designed not only in the replacement tank, but also in the outgoing pipe where the paint liquid in the electrodeposition tank is transferred to the replacement tank,
The inside of the return pipe that returns the paint liquid in the replacement tank to the electrodeposition tank can also be thoroughly cleaned with a large amount of cleaning water supplied to the replacement tank, and the used cleaning water used for cleaning is not wasted. Also, without wastewater treatment,
It is an object of the present invention to provide an electrodeposition coating device that can reliably prevent a rise in the water level in an electrodeposition tank without providing an unnecessary relay tank or the like for storing the washing water.

[Means for solving problems]

In order to achieve this objective, the present invention provides that an outgoing pipe for transferring the paint liquid in the electrodeposition tank to the replacement tank and a return pipe for returning the paint liquid in the replacement tank to the electrodeposition tank are used as paint liquid circulation system piping. In the electrodeposition coating equipment connected to the tank, when the paint liquid in the displacement tank is returned to the electrodeposition tank, the outgoing pipe and the return pipe are connected to each other by switching the valve, and the paint liquid is supplied into the replacement tank. A cleaning water circulation system piping for circulating cleaning water is formed, and the dip is connected to the dip via water supply piping connected between the washing water tank and the cleaning water circulation system piping for washing the workpiece carried out from the electrodeposition bath. The washing water in the washing tank is supplied to the replacement tank, and when the washing water is circulated and the washing in the replacement tank and the washing water circulation system piping is completed, the used washing water is passed through the water supply pipe to the deep washing tank. It is characterized by being configured to be returned to the tank.

[Effect]

According to the present invention, when the paint liquid in the replacement tank is returned to the electrodeposition tank, there is an outgoing pipe that transfers the paint liquid in the electrodeposition tank to the replacement tank, and the paint liquid in the replacement tank is returned to the electrodeposition tank. The return pipe and the return pipe are connected to each other by switching the valves to form a wash water circulation system piping that circulates the wash water supplied into the displacement tank, so that the return pipe and the return pipe are connected to each other by switching the valves to form a wash water circulation system piping that circulates the wash water supplied to the displacement tank. The inside of the return pipe is also thoroughly cleaned, and paint residues are reliably prevented from forming inside these pipes.

Further, since the replacement tank is supplied with the abundant cleaning water stored in the deep washing tank, the interior of the replacement tank, the outgoing pipe, and the return pipe can be sufficiently cleaned with a large amount of cleaning water.

Furthermore, since the used washing water is returned to the original dip rinsing tank, it may become impossible to control the level of the paint liquid stored in the tank body of the electrodeposition tank due to a rise in the water level in the electrodeposition tank. Definitely prevented.

In addition, general electrodeposition coating equipment is always equipped with a filtration device that separates paint components from the washing water in the dip washing tank. The wash water is purified and the paint contained during the wash is recovered.

Therefore, there is no need to provide extra equipment such as a relay tank to store used washing water between the replacement tank and the electrodeposition tank, and the washing water does not need to be wastefully disposed of through drainage treatment. It's over.

〔Example〕

Embodiments of the present invention will be specifically described below based on the drawings.

FIG. 1 is a flow sheet diagram showing an example of an electrodeposition coating apparatus according to the present invention.

Note that portions corresponding to those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In this example, the outgoing pipe 10 and the return pipe 11 are connected to the paint liquid circulation system piping 4 through a common pipe line on the discharge side of the circulation pump 5, and the paint liquid in the displacement tank 9 is transferred to the return pipe. 11 through the paint liquid circulation system piping 4 to the electrodeposition tank 1, the cleaning water is connected to each other by switching the valves 20 and 21, thereby circulating the cleaning water supplied into the displacement tank 9. A system piping S is formed.

That is, when the paint liquid in the displacement tank 9 is returned to the electrodeposition tank 1 by the pump 13 installed in the return pipe 11,
The valve 20 that opened the pipe leading to the paint liquid circulation system pipe 4 was closed, the valve 21 that had closed the pipe leading to the outgoing pipe 10 was opened, and the displacement tank 9 was opened.
A cleaning water circulation system piping S is formed that circulates the cleaning water supplied to the tank from the return pipe 11 through the outgoing pipe 10 and back into the replacement tank 9.

In this state, a dip-type third washing tank 22 is used to wash the object to be coated taken out from the electrodeposition tank 1.
Wash water in the dip wash tank 22 is supplied to the replacement tank 9 through a water supply pipe 23 connected between the pipe S and the wash water circulation system pipe S.

In this case, the normal dip washing tank 22
stores approximately 70 tons of washing water,
A more than sufficient amount of washing water can be supplied to the replacement tank 9.

Note that one end of the water supply pipe 23 is connected via a valve 26 to the discharge side of a circulation pump 25 installed in a wash water circulation system pipe 24 that circulates wash water in the dip wash tank 22, and the other end is ,
It is connected via a valve 27 to a cleaning water circulation system piping S consisting of an outgoing pipe 10 and a return pipe 11.

Therefore, when cleaning the inside of the substitution tank 9 after returning the paint liquid to the electrodeposition tank 1, the valves 26 and 27 installed at both ends of the water supply pipe 23 are opened, and the cleaning water circulation system pipe is opened. Circulation pump 25 interposed in 24
By activating , the washing water in the dip washing tank 22 is supplied to the replacement tank 9 .

When the supply of washing water from the dip washing tank 22 to the displacement tank 9 is completed, the circulation pump 25 is stopped, the valves 26 and 27 installed in the water supply pipe 23 are closed, and then the water is sent to the return pipe 11. The pump 13 is started, and the inside of the displacement tank 9, the outgoing pipe 10, and the return pipe 11 are thoroughly cleaned by circulation of the washing water.

When the cleaning is completed in this way, the valves 26 and 27 installed at both ends of the water supply pipe 23 are opened, and the used cleaning water is transferred from the water supply pipe 23 to the cleaning water circulation system by the pump 13 installed in the return pipe 11. It is returned to the original dip washing tank 22 through the pipe 24.

In this way, if the used washing water is returned to the original dip washing tank 22 without returning to the electrodeposition tank 1, the paint accumulated in the tank body 2 due to the rise in the water level of the electrodeposition tank 1 can be removed. It is possible to eliminate the damage caused by the inability to control the liquid level.

After the used washing water is returned to the dip washing tank 22, the valve 26 of the water supply pipe 23 is closed, and the washing water in the dip washing tank 22 is transferred to the circulation pump installed in the washing water circulation system pipe 24. At the same time, clean washing water is started to be supplied into the dip washing tank 22 from the riser pipe 29 of the shower device 28 provided at the subsequent stage.

As a result, the washing water in the dip washing tank 22 is constantly agitated to prevent the paint components contained in the washing water from settling, and the washing water contaminated with paint is removed from the clean water supplied from the shower device 28. The cleaning water is diluted with cleaning water and overflows in the order of the shower-type second rinsing tank 30 and first rinsing tank 31 provided in the previous stage, is sent to the sub tank 3 of the electrodeposition tank 1, and is returned to the dip rinsing tank 22. The concentration of paint contamination in water will gradually decrease.

From the sub-tank 3 into which overflowing wash water is sent from the wash tanks 22, 30, and 31 in this order, a pump 32 constantly pumps a certain amount of paint liquid to the UF (Ultra Filtration) device, etc. A concentrated liquid of paint components, which is fed to the outer filtration device 33 and separated from the paint liquid by the filtration device 33, is returned to the sub-tank 3 through a pipe 34.

Further, the filtrate obtained by separating the paint components by the ultrafiltration device 33 is stored in a tank 35.
from the tank 35 to the water tank 3 of the shower device 28 by a pump 37 interposed in the piping 36.
8. The filtrate stored in this water tank 38 is then transferred to the riser pipe 29 by a pump 39.
is injected from. Note that when the amount of water in the water tank 38 is insufficient, pure water is replenished from the water supply pipe 40.

In this way, the filtrate and pure water are supplied into the dip washing tank 22 into which the used washing water is returned, and at the same time, the contaminated washing water in the washing tank 22 is overflowed and discharged, and the discharged washing water is discharged. When the water is purified by the filtration device 33 and circulated again into the dip washing tank 22, the washing water in the washing tank 22 is gradually purified and automatically returns to its original clean state.

Here, since the normal filtration device 33 can process approximately 2 tons of water per hour, the time required for the washing water in the dip washing tank 22 to reach a state where it can be used for washing the object to be coated is It takes about 35 hours. Therefore, if you use the two days off, Saturday and Sunday, you can clean and inspect the inside of the electrodeposition tank 1.
The cleaning work of the replacement tank 9 can be completed satisfactorily.

In the above embodiment, the water supply pipe connected between the wash water circulation system pipe S and the dip flush tank 22 is one pipe 23, but the present invention is not limited to this, and even if two pipes 14 are used. good.

In addition, a portion of the used cleaning water is transferred from the cleaning water circulation system piping S to the paint liquid circulation system piping 4 within the limit that does not make it impossible to control the liquid level of the paint liquid stored in the tank body 2 of the electrodeposition tank 1. Of course, it may be returned into the electrodeposition tank 1 through the electrodeposition tank 1.

〔Effect of the invention〕

As described above, according to the present invention, when the paint liquid in the replacement tank is returned to the replacement tank, the outgoing pipe for transferring the paint liquid in the electrodeposition tank to the replacement tank and the paint liquid in the replacement tank are connected to each other. The return pipes that return to the electrodeposition tank are connected to each other to form a cleaning water circulation system piping that circulates the cleaning water supplied into the replacement tank, so that not only the inside of the replacement tank but also the outgoing pipe and The inside of the return pipe was also cleaned,
This has the excellent effect of reliably preventing paint residue from forming inside these pipes.

In addition, since the abundant washing water in the dip washing tank can be fully used for washing water, the inside of the displacement tank, outgoing pipe, and return pipe can be sufficiently washed with a large amount of washing water. There is.

Furthermore, since the used washing water used for cleaning is returned to the original dip rinsing tank, the level of the paint liquid stored in the tank body of the electrodeposition tank can be controlled due to the rise in the water level in the electrodeposition tank. It has the excellent effect of reliably preventing incapacity.

[Brief explanation of drawings]

FIG. 1 is a flow sheet diagram showing an example of an electrodeposition coating apparatus according to the present invention, and FIG. 2 is a flow sheet diagram showing a conventional apparatus. Explanation of symbols 1...electrodeposition tank, 2...tank body, 3
...Sub tank, 4...Paint liquid circulation system piping, 9...Displacement tank, 10...Outgoing pipe, 11...Return pipe, S...Washing water circulation system piping, 22...Dip washing tank, 23...Water supply piping.

Claims (1)

[Claims] 1 An outgoing pipe that transfers the paint liquid in the electrodeposition tank to the replacement tank and a return pipe that returns the paint liquid in the replacement tank to the electrodeposition tank are connected to the paint liquid circulation system piping. When the paint liquid in the tank is returned to the electrodeposition tank,
By switching the valve, the outgoing pipe and the return pipe are connected to each other, forming a cleaning water circulation system piping that circulates the cleaning water supplied to the displacement tank, and also connects the workpieces carried out from the electrodeposition tank. The wash water in the dip wash tank is supplied to the replacement tank through a water supply pipe connected between the dip wash tank and the wash water circulation system piping, and the wash water is circulated to the replacement tank and the wash water circulation system. An electrodeposition coating apparatus characterized in that, when cleaning inside the system piping is completed, the used cleaning water is returned to the dip rinsing tank through the water supply piping.