JP2000226696A - Electrodeposition coater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeposition coater by which the electrodeposition bubble floating on the surface of a coating liq. is prevented from depositing on a material to be coated. SOLUTION: This electrodeposition coater has an electrodeposition tank 1 filled with a coating liq. L, coating liq. circulating lines 12, 21 and 31 to let the liq. in the tank 1 flow in the longitudinal direction of the tank 1 and a overflow tank 3 installed at the outlet side of the tank 1. In this case, a nozzle 315a is provided to direct the surface flow of the electrodeposition tank on the overflow tank 3 side toward the overflow tank 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-dip or half-dip electrodeposition coating apparatus installed in a coating line for an automobile body or an automobile part, and more particularly to an electrodeposition foam floating on a coating liquid surface. The present invention relates to an electrodeposition coating apparatus capable of preventing the adhesion of a coating.

[0002]

2. Description of the Related Art As a coating system for an automobile body, a three-coat coating system consisting of a base coat, a middle coat and a top coat is widely used. Alternatively, in a process such as electrodeposition coating, a dipping coating method in which an automobile body is completely immersed in a processing liquid or a coating liquid is widely used.

In this type of dipping coating method,
Since the continuously transported automobile body needs to be completely immersed for a predetermined time, a large amount of a processing liquid or a coating liquid is stored in the processing tank or the coating tank.

[0004] In particular, since the electrodeposition coating liquid is diluted to a low solid content, sedimentation of the pigment occurs unless constantly or intermittently agitated, and the amount contained in the tank is large.
Once the pigment has settled, it is very difficult to redisperse. If the pigment dispersion in the electrodeposition coating liquid is not uniform, the gloss of the coating film fluctuates, which affects the overcoat film.

[0005] In electrodeposition coating in which a coating is formed by electrophoresis, a reactive gas is generated on the surface to be coated when the coating is formed, that is, at the time of dipping. And become coating defects.
From this point of view, it is necessary to give an appropriate flow rate to the electrodeposition coating liquid in the tank, thereby removing the reaction gas from the surface to be coated.

Furthermore, in electrodeposition coating, reaction heat is generated during the formation of a coating film, so that the temperature of the coating material near the surface to be coated rises and the resistance of the coating film decreases. . If the electrodeposited film thickness is non-uniform, the surface quality of the coating film, for example, sharpness and coating surface become non-uniform. Therefore, the agitation in the tank is necessary also from the viewpoint of sending the appropriate temperature coating liquid to the surface to be coated and cooling.

On the other hand, in the welding process, which is a pre-process of the painting process, the vehicle body panels are joined by spot welding or arc welding and assembled, so that the metal powder such as spatter at the time of the spot welding adheres to the vehicle body while the painting process is performed. It is carried in. In the pretreatment step of the electrodeposition coating step, a multi-step washing step is provided to wash such foreign matters, but it is not possible to completely remove fine metal powder and foreign matters adhering to the room.

When such metal powder is brought into the electrodeposition tank, it is re-adhered to an automobile body, particularly to a horizontal portion, etc.
Penetration into the electrodeposited coating will cause coating defects. For this reason, the inside of the tank is used for the purpose of removing foreign matter such as metal powder that is likely to adhere to the surface to be coated and discharging the foreign matter to the outside of the tank by a filter.

As described above, the agitation in the electrodeposition tank is performed from various viewpoints such as prevention of pigment sedimentation, uniformization of pigment dispersion, removal of bubbles and heat, and prevention of adhesion of foreign matter.

The applicant of the present application has previously proposed that the liquid flow direction in the electrodeposition tank be opposed to the moving direction of the body, and that an overflow tank be disposed on the entry side of the electrodeposition tank. By doing so, the relative speed between the liquid flow and the body is increased, the effect of removing bubbles and reaction heat is enhanced, and dust introduced by the body can be directly discharged from the tank into the overflow tank.

[0011]

However, in this type of liquid-flow facing electrodeposition coating, the surface flow of the electrodeposition tank flows down from the outlet to the tank of the electrodeposition tank. Electrodeposited bubbles are generated on the outlet side due to the return liquid and the outlet of the body, and the bubbles float on the liquid surface and flow toward the inlet side. For this reason, when the body enters or leaves the tank, there is a problem in that the flowing bubbles are entrapped and an appropriate coating film cannot be formed.

The present invention has been made in view of such problems of the prior art, and provides an electrodeposition coating apparatus capable of preventing electrodeposition bubbles floating on a coating liquid surface from adhering to an object to be coated. The purpose is to:

[0013]

According to a first aspect of the present invention, there is provided an electrodeposition coating apparatus comprising: an electrodeposition tank filled with a coating liquid; And a coating liquid circulation system in which the flow of the coating liquid in one direction along the longitudinal direction of the electrodeposition tank is provided, and the coating liquid circulation system is provided on the upstream side in the one direction among the entry side or the exit side of the electrodeposition tank. In the electrodeposition coating apparatus having an overflow tank, the surface flow of a predetermined area on the overflow tank side of the electrodeposition tank,
It is characterized by further comprising a surface flow adjusting means for adjusting the direction toward the overflow tank.

According to the first aspect of the present invention, the flow of the coating liquid in the electrodeposition tank is made to flow in one direction by the coating liquid circulation system. An overflow tank is provided.) The surface flow in a predetermined area is directed to the overflow tank.
Therefore, even if electrodeposited bubbles are generated on the upstream side in one direction, the electrodeposited bubbles are directly guided to the overflow tank provided on the upstream side by the surface flow adjusting means, whereby the electrodeposited bubbles are formed. It is prevented from spreading inside.

The predetermined area on the overflow tank side of the electrodeposition tank according to the first aspect of the present invention is not particularly limited with respect to the longitudinal direction of the electrodeposition tank. 10% to 30% of the total tank length (more preferably 2% to 30%)
0%). If the length of the predetermined region in the longitudinal direction is less than 10%, the effect of removing the electrodeposited bubbles by the surface flow adjusting means cannot be sufficiently expected. Conversely, if the length of the predetermined region in the longitudinal direction exceeds 30%. This is because the effect of the original one-way coating liquid flow cannot be sufficiently expected.

However, the predetermined area in the first aspect of the present invention can be specified by a physical quantity other than the length of the electrodeposition tank. In other words, according to the third aspect of the present invention, the surface flow adjusting means sucks the coating liquid in an amount of 10% to 30% of the coating liquid filled in the electrodeposition tank from the electrodeposition tank or the overflow tank. Then, this is discharged into the electrodeposition tank.

The predetermined area on the overflow tank side of the electrodeposition tank is 10 times the entire length of the electrodeposition tank.
% To 30%, if the circulation amount of the coating liquid (discharge amount to the electrodeposition tank) can be sufficiently secured by the surface adjusting means, the electrodeposited bubbles generated on the outlet side overflow as they are. Can be led to the tank. 10% to 30% in this case
Is the ratio of the coating liquid in the electrodeposition tank to the total circulation amount of the coating liquid, and the remaining coating liquid is provided to the coating liquid in one direction by the coating circulation system.

The surface flow in the predetermined region according to the first to third aspects of the present invention is not particularly limited. However, as long as the effect of the paint flow in one direction is not significantly impaired, the surface flow is defined as being below the liquid surface in the vertical direction. It means an area with a certain width toward it.
In this way, in addition to guiding the large electrodeposited bubbles floating on the liquid surface to the overflow tank, even bubbles that are about to float on the liquid surface can be guided to the overflow tank.

The specific structure of the surface adjusting means in the above invention is not particularly limited. For example, as in the invention according to the fourth aspect, the surface flow adjusting means is configured to suck the coating liquid from the electrodeposition tank or the overflow tank. And a circulating system including a pump for discharging the liquid into the electrodeposition tank.

In the above invention, it is within the scope of the present invention to provide another overflow tank at another position as long as the overflow tank is installed at least upstream in one direction.

In the above invention, the relationship between the flow direction (one direction) of the coating liquid in the electrodeposition tank and the moving direction of the object to be coated is not particularly limited, and the same direction or the opposite direction is included in the present invention. It is. In particular, in the invention according to claim 5, the one direction is a direction opposed to a moving direction of the object to be coated, and the overflow tank is provided on the outlet side of the electrodeposition tank. I do.

According to the fifth aspect of the present invention, since the flow of the coating liquid in the electrodeposition tank is in one direction, an appropriate liquid flow that does not stay in the electrodeposition tank is ensured.
This prevents pigment sedimentation or uniform pigment dispersion,
Removal of air bubbles and heat and prevention of adhesion of foreign matter can be achieved. In addition, since the liquid flow direction of the electrodeposition tank is opposed to the moving direction of the object to be coated, the relative speed between the liquid flow and the object to be coated can be increased, and as a result, the metal contained in the electrodeposition liquid can be increased. Adhesion of foreign substances such as powder can be more effectively prevented, and air bubbles and heat generated on the surface of the object can be effectively removed. In particular, if an overflow tank is provided on the entry side of the electrodeposition tank, foreign substances brought in at the time of entry of the object to be coated can be flowed out to the overflow tank as it is, thereby forming a coating film such as "Butsu" Defects can be reduced.

(2) In order to achieve the above object, the electrodeposition coating apparatus according to the sixth aspect of the present invention is characterized in that a voltage is applied between an electrode immersed in a coating liquid in an electrodeposition tank and an electrode. A first circulatory system in which at least the flow of the coating liquid in the electrodeposition tank is in one direction, and at least a surface flow on the upstream side in the one direction. And a second circulatory system that makes the direction opposite to the one direction.

In this case, although not particularly limited, claim 7
As in the invention described, each of the first circulating system and the second circulating system has a pump that sucks the coating liquid in the electrodeposition tank or the overflow tank, and discharges the pump into the electrodeposition tank. More preferably, a plurality of nozzles are provided on a side wall and / or a bottom surface in the electrodeposition bath.

With respect to the flow direction of the coating liquid in the electrodeposition tank,
In making the upstream surface flow in the opposite direction, by using a plurality of nozzles provided on the side wall and / or the bottom surface in the electrodeposition tank as the second circulation system, existing nozzles can be used. . That is, by turning the nozzle provided on the upstream side in one direction in the opposite direction and turning the other nozzles in one direction, existing equipment can be easily diverted without extensive remodeling work. .

However, in order for the main flow direction of the coating liquid in the electrodeposition tank to be one direction, the first circulating system is provided on the downstream side in the one direction. More preferably, the apparatus further includes a hopper provided in the electrodeposition tank for sucking the coating liquid in the electrodeposition tank.

By doing so, most of the coating liquid (for example, 70% to 90%) in the electrodeposition tank can be sucked and discharged into the electrodeposition tank, so that the paint flow in one direction can be realized.

(3) The immersion method for the object to be coated in the electrodeposition coating apparatus of the present invention described above includes a full dip method in which the object is completely immersed and a half-dip method in which a part of the object is immersed. And law. Further, the electrodeposition coating apparatus of the present invention can be applied to electrodeposition coating of various metal parts such as an automobile body and an automobile part.

[0029]

According to the first to fifth aspects of the present invention, even if electrodeposited bubbles are generated on the upstream side in one direction, the electrodeposited bubbles are provided on the upstream side by the surface flow adjusting means. Since the liquid is directly guided to the tank, it is possible to prevent the electrodeposition foam from spreading into the electrodeposition tank. As a result, bubbles are prevented from being entrained in the object to be coated, and the incidence of coating film defects is reduced.

In addition, according to the second and third aspects of the present invention, a paint flow in one main direction in the electrodeposition tank can be realized, thereby effectively preventing dust from adhering to the object to be coated. In addition, air bubbles and heat generated on the surface of the object to be coated can be effectively removed.

According to the fifth aspect of the invention, the relative speed between the liquid flow and the object to be coated can be increased, and as a result,
Adhesion of foreign matter such as metal powder contained in the electrodeposition liquid can be more effectively prevented, and bubbles and heat generated on the surface of the object can be more effectively removed. Further, since the liquid flow speed can be reduced to a speed at which pigment sedimentation does not occur, energy saving can be achieved by reducing the capacity of the circulation system to a necessary minimum. In addition, if an overflow tank is provided on the entry side of the electrodeposition tank, foreign substances brought in at the time of entry of the object to be coated can be flowed out to the overflow tank as it is, so that a coating film such as "buts" can be formed. Defects can be reduced.

According to the inventions described in claims 6 to 8, the existing equipment can be easily diverted without large-scale remodeling work to achieve the proper one-way flow and the prevention of foam diffusion. it can.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing an embodiment of an electrodeposition coating apparatus of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 shows a coating liquid flow in an electrodeposition tank of the embodiment. It is sectional drawing.

The electrodeposition coating apparatus of this embodiment has a long boat-shaped electrodeposition tank 1, and the electrodeposition tank 1 is filled with an electrodeposition coating liquid L. The car body B to be coated is a hanger H
The overhead conveyor C is transported at a constant speed by the overhead conveyor C in a state where the overhead conveyor C is placed at about 20 ° on the entrance side of the electrodeposition tank 1 in order to completely sink the body B into the electrodeposition tank 1. In the effective range of the electrodeposition tank, the body B is kept at a height where the body B is completely immersed, and the inclination is about 20 ° to 40 ° on the outlet side. In FIG. 1, the left side of the figure is the tank entrance side and the right side is the tank exit side.

The effective range of the electrodeposition tank, that is, the length of the electrodeposition tank 1 in the range in which the body B is completely immersed, is set such that a total immersion time of, for example, 3 minutes or more is secured. When the body B is put in the tank, in the cationic electrodeposition paint, via the electrode plate 4 (see FIG. 2) arranged on the side wall and the bottom wall of the electrodeposition tank 1,
A DC voltage of about 300 V is applied to the electrodeposition paint L, thereby causing electrophoresis of the paint particles between the grounded body B and the electrodeposition coating film formed on the inner and outer plates of the body B and the inner surface of the bag structure. You.

A hopper 11 is provided on the bottom surface of the electrodeposition tank 1 on the entry side.
The hopper 11 is for collecting a part of the electrodeposition coating liquid L that has flowed down from the outlet side to the inlet side in the electrodeposition tank 1, and the tip thereof has a coating material. Piping 12
1, a suction pump 122, a filter 123, and a heat exchanger 124 are provided, and a plurality of nozzles 125 are provided at the tip thereof.

These constitute a first electrodeposition liquid circulation system 12, whereby a part of the electrodeposition coating liquid L flowing down the electrodeposition tank 1 from the exit side to the entry side is transferred to the hopper 11. guided by,
After being suctioned by the pump 122 and filtered by the filter 123, the temperature is controlled to an appropriate value by the heat exchanger 124, and the water is discharged again from the nozzle 125 toward the entry side in the electrodeposition tank 1.

The nozzle 12 of the first electrodeposition liquid circulation system 12
Numeral 5 is attached to, for example, each of a plurality of pipes erected on the bottom surface and both side walls of the electrodeposition tank 1, and provided so that the discharge direction of the electrodeposition coating liquid L is in the direction of the arrow in FIG. .

As shown in FIG. 2, the nozzle 125 provided on the bottom surface of the electrodeposition tank 1 is provided on the side wall (right side in the figure) of the electrodeposition tank 1.
Is provided from the main pipe P1 extending in the longitudinal direction, extending beyond the upper edge of the electrodeposition tank 1, and extending along the width of the side surface along the inner surface of the side wall. The nozzle 125 is mounted here. Such branch pipes are provided at a predetermined pitch in the longitudinal direction of the electrodeposition tank 1. On the other hand, the nozzles 125 provided on both side walls of the electrodeposition tank 1 are provided on the side walls (left side in the figure) of the electrodeposition tank 1.
Is branched from the main pipe P2 extending in the longitudinal direction, exceeds the upper edge of the electrodeposition tank 1, and hangs down on the inner surface of the side wall. The nozzle 125 is mounted here. This branch pipe is also provided at a predetermined pitch with respect to the longitudinal direction of the electrodeposition tank. Although only the left side is shown in FIG. 2, the same main pipe P2, branch pipe and nozzle 125 are provided on the right side wall of the electrodeposition tank 1. Is also provided.

In this example, as shown in FIG. 1, the electrodeposition tank 1 is mounted on a plurality of pipes provided on the bottom surface and both side walls at the center. Along with the later-described second and third electrodeposition liquid circulation systems 13 and 14, a discharge force from these nozzles 125 causes a one-way liquid flow in the electrodeposition tank 1.

Overflow tanks 2 and 3 are provided outside the entrance and exit sides of the electrodeposition tank 1, respectively, and a weir 2 between the electrodeposition tank 1 and the overflow tanks 2 and 3 is provided.
The electrodeposition coating liquid L that has exceeded 2 and 32 flows into the overflow tanks 2 and 3. Therefore, the liquid level of the electrodeposition tank 1 is determined by the height of the weirs 22 and 32.

A suction pump 212, a filter 213, and a
A second having a heat exchanger 214 and a plurality of nozzles 215
The electrodeposition coating liquid L in the overflow tank 2 is sucked by the pump 212 and filtered by the filter 213, and then the heat exchanger 214
Is adjusted to an appropriate temperature, and is discharged from the nozzle 215 into the electrodeposition tank 1.

The nozzle 21 of the second electrodeposition liquid circulation system 21
5 is attached to each of a plurality of pipes provided in the width direction on both side walls and the bottom surface of the electrodeposition tank 1 on the entry side, for example, so that the discharge direction of the electrodeposition coating liquid L is directed to the entry side. Provided.

In the overflow tank 3 on the outlet side, a suction pump 312, a filter 313,
A third electrodeposition liquid circulation system 31 having a heat exchanger 314 and a plurality of nozzles 315 and 315a is provided.
After being suctioned by the filter 2 and filtered by the filter 313, the temperature is adjusted to an appropriate temperature by the heat exchanger 314, and the nozzles 315 and 3
15a is discharged into the electrodeposition tank 1.

The nozzle 31 of the third electrodeposition liquid circulation system 31
5, 315a is attached to each of a plurality of pipes provided in the width direction on both side walls and the bottom surface on the outlet side of the electrodeposition tank 1, for example.

Particularly in the present embodiment, among the nozzles of the third electrodeposition liquid circulation system 31, the nozzle 315 provided on the bottom surface (strictly, the inclined bottom surface) of the electrodeposition tank 1 is provided with the electrodeposition coating liquid L. The nozzles 315a provided on both side walls of the electrodeposition tank 1 are attached to the pipe so that the discharge direction is toward the tank entrance side.
The electrodeposition coating liquid L is mounted so that the discharge direction of the electrodeposition coating liquid L is toward the outlet tank, that is, toward the overflow tank 3.

The area in which the nozzle 315a for discharging in the opposite direction is provided can be specified by the length in the longitudinal direction of the electrodeposition tank 1, as shown in FIG.
The range is 30%. Similarly, if specified by the circulation amount of the electrodeposition coating liquid L, the ratio of the electrodeposition coating liquid L discharged from the nozzle 315a is 10% to 30%.

Also, a nozzle 315a for discharging in the opposite direction
If specified in the depth direction of the electrodeposition tank 1, it is sufficient that the depth is such that a surface flow sufficient to guide the electrodeposited bubbles floating on the liquid surface to the overflow tank 3, that is, at least a region close to the liquid surface. 1, in the example shown in FIG.
Are mounted in the reverse direction, and the lowermost nozzle 315 is mounted in the forward direction.

Next, the operation will be described. FIG. 3 shows the inside of the electrodeposition tank 1 when the first to third coating liquid circulation systems 12, 21, 31 are driven to circulate the electrodeposition coating liquid L in the electrodeposition tank 1 and the overflow tanks 2, 3. Are indicated by arrows.

The first to third coating liquid circulation systems 12, 21,
When the pump 31 is driven, the electrodeposition coating liquid L in the electrodeposition tank 1 and the overflow tanks 2 and 3 is sucked, and the electrodeposition coating liquid L is filtered by a filter and adjusted to an appropriate temperature by a heat exchanger. After that, the plurality of nozzles 125, 2
It is discharged to the electrodeposition tank 1 from 15, 315, 315a. Of these nozzles, a large one-way liquid flow from the outlet section to the inlet section is generated as a whole by the discharge force of the coating liquid L from the nozzles 125, 215, and 315 (right in FIG. 3). From left to left).

When the body B is immersed in the thus-stirred electrodeposition coating liquid L, bubbles are generated by the reaction heat generated on the surface thereof, float on the liquid surface and appear as bubbles S. In addition, bubbles S are generated on the liquid surface even when the electrodeposition paint is dropped when the body B leaves the tank at the outlet part. Furthermore, electrodeposition tank 1
The recovered liquid in the subsequent rinsing step, particularly in the UF (ultrafiltration) rinsing step, flows into the overflow tank 3, so that bubbles S are also generated in the overflow tank 3,
Over the electrodeposition tank 1.

However, in the electrodeposition coating apparatus of this embodiment, the nozzle 315a provided on both side walls on the outlet side causes the surface flow near the outlet to be opposite to the main flow as shown in FIG. The bubble S flows in the direction (from left to right in FIG. 3), and the bubbles S which are going to enter the electrodeposition tank 1 or are generated in the outlet section flow out onto the overflow tank 3 on the surface flow in the opposite direction. Will be. Thereby, the spread of the electrodeposited bubbles in the electrodeposition tank 1 is prevented, and the entrainment of the bubbles into the body B can be prevented.

Further, the main body in the electrodeposition tank 1
Is formed, the relative speed between the body B and the coating liquid L in the tank is increased, and as a result, adhesion of dust to the body B can be more effectively prevented. . In addition, bubbles and heat generated on the body surface can be effectively removed.

Furthermore, in the present embodiment, the main flow and the surface flow in the tank can be adjusted mainly by the arrangement and the mounting direction of the nozzles. Therefore, most of the existing facilities are manufactured without major remodeling work. be able to.

The embodiments described above are described for facilitating the understanding of the present invention, but not for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above-described embodiment, the overflow tank 2 is provided also on the entry side, but in the electrodeposition coating apparatus of the present invention, it is necessary to provide the overflow tank 2 on the downstream side in the main flow direction of the electrodeposition tank 1. Absent.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an electrodeposition coating apparatus of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a cross-sectional view showing a coating liquid flow in the electrodeposition tank shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrodeposition tank 12 ... 1st electrodeposition liquid circulation system (paint liquid circulation system) 2, 3 ... Overflow tank 21 ... 2nd electrodeposition liquid circulation system (paint liquid circulation system) 31 ... 3rd electrodeposition Liquid circulation system (paint liquid circulation system) 315a: nozzle (surface flow adjusting means) B: automobile body (object to be processed) C: overhead conveyor

Claims (8)

[Claims] 1. An electrodeposition tank filled with a coating liquid, a coating liquid circulation system in which the flow of the coating liquid in the electrodeposition tank is in one direction along a longitudinal direction of the electrodeposition tank, and the electrodeposition tank. An electrodeposition coating apparatus having an overflow tank provided on the upstream side in the one direction out of the tank side or the tank side, wherein the surface flow of a predetermined area of the overflow tank side of the electrodeposition tank is An electrodeposition coating apparatus further comprising a surface flow adjusting means for directing the flow toward the overflow tank. 2. The predetermined area where the surface flow is directed to the overflow tank is 10% to 3% of the total length of the electrodeposition tank.
2. The electrodeposition coating apparatus according to claim 1, wherein the length is 0%. 3. The method according to claim 1, wherein the surface flow adjusting means sucks a coating liquid in an amount of 10% to 30% of the coating liquid filled in the electrodeposition tank from the electrodeposition tank or the overflow tank, and sucks the liquid. 2. The immersion type surface treatment apparatus according to claim 1, wherein the apparatus is discharged into an electrodeposition tank. 4. A pump for sucking a coating liquid from the electrodeposition tank or the overflow tank;
The electrodeposition coating apparatus according to any one of claims 1 to 3, further comprising a nozzle for discharging the liquid into the electrodeposition tank. 5. The apparatus according to claim 1, wherein the one direction is a direction facing a moving direction of the object to be coated, and the overflow tank is provided on a discharge side of the electrodeposition tank. 4
An electrodeposition coating apparatus according to any one of the above. 6. An electrodeposition coating apparatus for applying a voltage between an object to be coated and an electrode immersed in a coating liquid in an electrodeposition tank to form a coating film, wherein at least the coating liquid in the electrodeposition tank is A first circulatory system having a flow in one direction, and a second circulatory system having at least a surface flow upstream of the one direction in a direction opposite to the one direction. Electrodeposition coating equipment. 7. Each of the first circulation system and the second circulation system includes a pump for sucking a coating liquid in the electrodeposition tank or the overflow tank, and a nozzle for discharging the coating liquid into the electrodeposition tank. The electrodeposition coating apparatus according to claim 6, wherein a plurality of the nozzles are provided on a side wall and / or a bottom surface in the electrodeposition tank. 8. The apparatus according to claim 1, wherein the first circulation system further includes a hopper provided in the electrodeposition tank on the downstream side in the one direction and for sucking a coating liquid in the electrodeposition tank. 7. The electrodeposition coating apparatus according to 7.