JPH0247295A - Electrodeposition coating device - Google Patents

Abstract

PURPOSE:To facilitate the resumption of the operation of an ultrafilter and to improve the efficiency in the filtration and recovery of a paint by replacing an electrodeposition paint in the ultrafilter with its filtrate when the operation of the title electrodeposition coating device provided with the ultrafilter is stopped. CONSTITUTION:The electrodeposition paint from the overflow vessel B of an electrodeposition bath A is introduced into the ultrafilter C, and filtered. The concd. paint is returned to the overflow vessel B through a pipe 11. The filtrate freed of paint by the filtration is introduced into a tank 12a and an auxiliary tank 12b, and then sent to a washing device W by a pump P2 to wash off the paint deposited on the surface of an electrodeposition-coated article. The filtrate is collected in a recovery tank 22, and then returned to the overflow vessel B. When the operation of the filtrafilter C is stopped, the electrodeposition paint in the ultrafilter C is replaced by the filtrate in the auxiliary tank 12b. Since the filtrate is sufficiently stored in the tank 12a when the operation is resumed, the washing filtrate can be supplied to the washing device W, hence the operation is smoothly resumed, and the efficiency in the filtration of paint is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrodeposition coating apparatus. More specifically, the electrodeposition paint in the electrodeposition bath is filtered by an ultrafiltration device, and the filtrate is used to wash the treated material taken out of the tank, and the electrodeposition paint taken out is recovered. This article relates to an electrodeposition coating device.

[Prior Art] A conventional electrodeposition coating apparatus equipped with the above-mentioned paint recovery system, which is employed in automobile manufacturing lines, will be explained with reference to FIG.

(A) is an electrodeposition bath, and (B) is its overflow tank. The electrocoating paint in the overflow tank (B) is sent by a supply pump (Pl) to an ultrafiltration device (C), where it is filtered. Concentrated electrodeposited paint is stored in an overflow tank (
B). The filtrate is sent to a filtrate tank (D) and from there to a cleaning device (envelope) by a filtrate pump (P2). In the cleaning device, the filtrate is sprayed onto the workpiece that has come out of the tank to wash off excess electrodeposited paint. The collected washing liquid is returned to the overflow tank (B).

During regular operation of the electrodeposition coating apparatus, the electrodeposition paint is recovered as described above.

[Problems to be Solved by the Invention] In recent years, from the viewpoint of energy conservation, it has become common practice to stop the operation of ultrafiltration devices except during production line operating hours to reduce power consumption.

In order to protect the ultrafiltration membrane, when the ultrafiltration apparatus is to be stopped, it is necessary to replace the electrocoating paint in the apparatus with the filtrate, wash the ultrafiltration membrane with the filtrate, and then stop the ultrafiltration apparatus. For this purpose, the filtrate in the filtrate tank (D) is supplied to the ultrafiltration device (C) via piping (2) for replacement. In this case, the operation will be stopped with the amount of filtrate in the filtrate tank (D) reduced.

When the production line is restarted under such conditions, the filtrate tank (
It is not possible to supply filtrate to the cleaning device (w) to fill D) with water, and as a result, there is a problem that the efficiency of paint recovery, which is the original purpose of the ultrafiltrate-based paint recovery system, decreases. .

In view of the above-mentioned points, the present invention aims to provide an electrodeposition coating apparatus that can achieve the same paint recovery efficiency as during steady operation even in the early stages of restarting the ultrafiltration apparatus after it has been stopped.

[Means for Solving the Problems] The present invention provides for sending the electrodeposition paint in the electrodeposition bath to an ultrafiltration device, sending the filtrate to a cleaning device via a filtrate tank, and using the filtrate to remove the coating material from the tank. The processed material is washed and the washing liquid is returned to the electrodeposition bath, and when the operation of the ultrafiltration device is stopped, the paint in the ultrafiltration device is replaced with the filtrate, and then the operation is stopped. In the electrodeposition coating equipment,
An auxiliary filtrate tank is installed in addition to the filtrate tank, and the filtrate piping from the ultrafiltration device is divided into two systems to supply the filtrate to the filtrate tank and the auxiliary filtrate tank, respectively, and the auxiliary filtrate is The tank is connected to the filtrate tank by an overflow pipe, and the filtrate is sent to the ultrafiltration device from the lower part of the auxiliary filtrate tank, and during steady operation of the electrodeposition coating device, the filtrate from the ultrafiltration device is transferred to the ultrafiltration device.
The filtrate is supplied to the two filtrate tanks and the auxiliary filtrate tank from the separate filtrate piping, and the filtrate is allowed to overflow from the auxiliary filtrate tank that is full to the filtrate tank, and when the ultrafiltration device is stopped, the filtrate in the auxiliary filtrate tank is drained into the ultrafiltrate tank. The present invention relates to an electrodeposition coating apparatus in which the filtrate is used to replace paint in a feeding device in a filtration device.

[Function] When the operation of the ultrafiltration device is stopped, the paint in the ultrafiltration device is replaced with the filtrate in the auxiliary filtrate tank, not the filtrate in the filtrate tank, and then the operation is stopped. Therefore, a predetermined amount of 7 filtrate is stored in the filtrate tank at the time of restarting the operation, as in the case of steady operation. Therefore, a predetermined amount of filtrate can be supplied to the cleaning device from the beginning of restart. The filtrate piping from the ultrafiltration device is divided into two systems, and the filtrate is supplied to the filtrate tank and the auxiliary filtrate tank, respectively. After the auxiliary filtrate tank is full, the filtrate overflows into the filtrate tank, so that the Fp liquid is maintained throughout the entire operation period. The amount of filtrate flowing into the tank becomes approximately constant.

[Example] Next, the present invention will be explained based on the drawings.

FIG. 1 is a schematic explanatory diagram showing an embodiment of the electrodeposition coating apparatus of the present invention.

The electrodeposition paint in the overflow tank (B) of the electrodeposition bath (A) is sent to the ultrafiltration device (C) by a supply pump (PL) through piping (G)), where it is filtered.

The electrocoating paint concentrated in the ultrafiltration device (C) is transferred to the pipe (It
) is returned to the overflow tank (B).

The filtrate piping 0 force is branched into piping (t2a) and piping (12b), and the filtrate is transmitted through piping (12a) and piping (12b).
b) to filtrate tank (D) and auxiliary filtrate tank (E)
are sent to each. When the auxiliary filtrate tank (E) is full, the filtrate overflows into the filtrate tank (D) through the overflow pipe (131).

The filtrate in the filtrate tank (D) is sent to the washing device (W) through the pipe Q41 by the filtrate pump (F2).

The cleaning device (W) includes a riser (2v) in the cleaning booth that sprays filtrate onto the object to be treated, and a pump that supplies the filtrate in the recovery tank n to the riser (21) in the recovery tank that collects the filtrate containing paint. A plurality of stages of such cleaning devices are provided.

The filtrate from the filtrate tank (D) is sent to the last stage recovery tank, where it is sprayed from the riser Qυ onto the object to be treated, and after washing off the electrodeposition paint that has adhered to the object and taken out, it is sent to the recovery tank. It can be stored in.

The paint-containing filtrate in the recovery tank n is transferred to the overflow pipe Q4.
It is sent to the previous stage recovery tank.

The filtrate, which has been used for cleaning in each stage in this way and has had an increased paint concentration, is returned to the overflow tank (B) from the surface of the collection tank at the first stage through the pipe (■) by the pump (□□□).

When the operation of the production line is to be stopped, after stopping the supply of paint to the ultrafiltration device (C), the filtrate in the auxiliary filtrate tank (E) is pumped into the ultrafilter through the piping port by the pump (F3). The paint is sent to the paint supply side of the filtration device (C) and the ultrafiltration device continues to operate, thereby replacing the paint in the device with the filtrate. After the replacement work is completed, remove the ultrafiltration device (C)
and the supply of filtrate from the filtrate tank (D) to the washing device (W), and the operation of the production line is stopped.

At this time, the filtrate tank (D) is full of water.

When the production line is restarted, the filtrate tank (D) is full of water, so the filtrate can be immediately supplied to the washing device (W). Note that the auxiliary filtrate tank (E) is almost empty when the ultrafiltration device (C) starts operating again, so the auxiliary filtrate tank (E) becomes full and the filtrate tank (D)
Until overflow occurs, the rate of filtrate flowing into the filtrate tank (D) is lower than during steady operation. However, the amount of filtrate flowing into the auxiliary filtrate tank (E) (F2) does not need to be that large (normally, it is enough to fill the water by the next time the operation is stopped), and the filtrate inflow from the piping (12a) (D
) to the filtrate inflow rate (Fl) should be about F2/Ft -8/100 to 10/100, so the filtrate supply flow rate from the filtrate tank (D) to the washing device (W) is It does not decrease enough to affect the paint recovery efficiency. Further, normally, the time from the start of operation until the auxiliary filtrate tank (E) becomes full of water and overflows to the filtrate tank (D) is set to about 480 to B00 minutes.

FIG. 2 shows the increase/decrease situation (1) of the filtrate in the filtrate tank (D) and the auxiliary filtrate tank (E) in the apparatus of the present invention in comparison with that in the conventional example (II). In Figure 2, ■~
■ means the following state.

■ During steady operation ■ When operation is stopped ■ Immediately after restarting operation ■ After a while (for example, several minutes) after restarting operation As is clear from Fig. 2, in the conventional example, from the time when the ultra-filter starts restarting Until the filtrate tank is full (■-■
-■) It is impossible to supply the filtrate to the cleaning device, whereas in the present invention, the ultrafiltration device is constantly supplied from the beginning of operation to the time of stopping, that is, when the ultrafiltration device is in operation. A predetermined amount of filtrate can be supplied to the cleaning device.

In the above embodiment, filtrate replacement when the ultrafiltration device is stopped is performed by supplying the replacement filtrate to the paint inflow side (forward direction) with respect to the ultrafiltration membrane. By changing the connection, the replacement filtrate may be supplied from the filtrate outflow side (reverse direction) of the ultrafiltration membrane for replacement.

[Effect of the invention] In an electrodeposition coating apparatus, filtrate can be supplied to the cleaning device from the initial stage when the ultrafiltration device in the paint recovery system is restarted after the operation is stopped, and the ultrafiltration device is always in operation. The specified paint recovery efficiency can be changed. Therefore, the start and stop of the operation of the ultrafiltration device can be made to coincide with the operation of the automobile production line, and energy saving can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram showing one embodiment of the electrodeposition coating apparatus of the present invention, and FIG.
An explanatory diagram comparing the increase/decrease situation of rJ liquid and that of a conventional example,
FIG. 3 is a schematic explanatory diagram showing a conventional electrodeposition coating apparatus. (Main symbols in the drawing) (A) Double electrodeposition bath (C): Ultrafiltration device No. 1 Garden E: Auxiliary filtrate tank 14.15: Piping (D): Filtrate tank (E) Auxiliary filtrate tank ( W): Cleaning device 02), (12a), (12b), (141, 6: Piping

Claims (1)

[Claims] 1. Send the electrodeposition paint in the electrodeposition bath to the ultrafiltrate device, send the filtrate to the cleaning device via the filtrate tank, wash the object to be treated taken out of the tank with the filtrate, and transfer the washing liquid to the electrodeposition bath. In the electrodeposition coating apparatus, the filtrate tank is configured to return to its original state, and when the operation of the ultrafiltration apparatus is stopped, the paint in the ultrafiltration apparatus is replaced with the filtrate before the operation is stopped. In addition, an auxiliary filtrate tank is installed, and the filtrate piping from the ultrafiltration device is divided into two systems to supply filtrate to the filtrate tank and the auxiliary filtrate tank, respectively, and the auxiliary filtrate tank is connected to an overflow pipe. is connected to the filtrate tank, and the filtrate is sent to the ultrafiltration device from the lower part of the auxiliary filtrate tank, and during steady operation of the electrodeposition coating device, the filtrate from the ultrafiltration device is divided into the two systems. The filtrate is supplied from the piping to the filtrate tank and the auxiliary filtrate tank, and the filtrate is allowed to overflow from the auxiliary filtrate tank that is full to the filtrate tank, and when the ultrafiltration device is stopped, the filtrate in the auxiliary filtrate tank is sent to the ultrafiltration device. An electrodeposition coating device that replaces paint with the filtrate.