JPH07150394A - Method for removing sludge depositing on electrode in electrodeposition coating device and device therefor - Google Patents

Abstract

PURPOSE:To prevent the diffusion of the sludge released from a bare electrode provided at the bottom of an electrodeposition tank into an electrodeposition paint and to prevent the deposition of the sludge on a material to be coated. CONSTITUTION:A side electrode 4 covered with a diaphragm 7 and a bare bottom electrode 5 having no diaphragm 7 are provided in an electrodeposition tank 1. The bottom electrode 5 is enclosed with an electrode case 24 on which a net permeable to an electrodeposition paint and impermeable to sludge is wound. A pump 28, filter 29 and flow control valve 30 are furnished to an electrodeposition paint circulating pipeline 26 with one end connected to the inside of the case 24 and the other end to a riser 31 in the tank 1. The sludge released from the bottom electrode 5 is sucked into the pipeline 26 along with the paint and passed through the filter 29, and a clean electrodeposition paint free from sludge is returned to the tank 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing sludge deposited on electrodes arranged in an electrodeposition tank of an electrodeposition coating apparatus, and an apparatus for carrying out the method.

[0002]

2. Description of the Related Art For example, in an electrodeposition coating apparatus used for undercoating an automobile body, the acid generated in the electrodeposition tank at the time of coating is discharged to the outside through a semipermeable membrane. It controls the pH of the paint. That is,
When the acid contained in the electrodeposition paint is sucked into the electrode (anode) housed in the diaphragm device, the polar liquid in this diaphragm device is discharged to the polar liquid tank, where it is diluted with pure water to be stored in the diaphragm device. Will be returned. As a result, the pH of the electrodeposition paint is maintained at an appropriate value.

[0003]

By the way, if a diaphragm device is provided for all the electrodes in the electrodeposition tank, the acid in the electrodeposition paint is excessively discharged. In this case, the electrode disposed at the bottom of the electrodeposition tank) was used as a bare electrode having no diaphragm device.

However, when sludge is deposited on the surface of a bare electrode having no diaphragm device, the sludge separated from the electrode diffuses into the electrodeposition paint and adheres to the object to be coated,
There was a problem that caused defective painting.

The present invention has been made in view of the above circumstances, and an object thereof is to prevent diffusion of sludge deposited on a bare electrode provided in an electrodeposition tank into an electrodeposition paint.

[0006]

In order to achieve the above object, the method of removing sludge from electrode precipitation in an electrodeposition coating apparatus according to claim 1 is such that an electrodeposition coating tank stores an electrodeposition coating tank. The dipped coating object is used as one electrode, the other electrode is arranged along the side wall and bottom wall of the electrodeposition tank, and the coating object is electrodeposited by applying a DC voltage to the one electrode and the other electrode. In an electrodeposition coating apparatus for coating, at least the periphery of the electrode disposed along the bottom wall of the electrodeposition tank is covered with a non-conductive electrode case that allows the passage of the electrodeposition coating and blocks the passage of electrode deposition sludge. At the same time, the electrodeposition coating material containing the electrode-precipitated sludge sucked from the electrode case by a pump is passed through a filter to filter the electrode-precipitated sludge and then returned to the electrodeposition tank.

Further, in the electrodeposition sludge removing device in the electrodeposition coating device according to the second aspect of the present invention, the electrodeposited sludge is immersed in the electrodeposition tank in which the electrodeposition coating material is stored, and one of the electrodes is used for electrodeposition. In the electrodeposition coating apparatus for arranging the other electrode along the side wall and the bottom wall of the tank, and applying the DC voltage to the one electrode and the other electrode to electrocoat the object to be coated,
A non-conductive electrode case which is provided so as to cover at least the periphery of the electrode arranged along the bottom wall of the electrodeposition tank, allows the passage of the electrodeposition paint, and prevents the passage of electrode deposition sludge,
An electrodeposition paint circulation pipe having one end opened in the electrode case and the other end connected to a riser provided in the electrodeposition tank,
A pump provided in the electrodeposition paint circulation pipe for sucking the electrodeposition paint containing electrode deposition sludge in the electrode case and supplying it to the riser, and a filter provided downstream of this pump for filtering the electrode deposition sludge It is characterized by having.

In addition to the structure of claim 2, the electrode deposition sludge removing device in the electrodeposition coating device according to claim 3 further includes a branch pipe branched from the filter downstream position of the electrodeposition paint circulation pipe. It is characterized in that it is opened in the electrode case.

According to a fourth aspect of the present invention, in the electrodeposition sludge removing device in the electrodeposition coating apparatus, in addition to the configuration of the second or third aspect, the electrode case has a cylindrical support having a large number of openings. It is characterized by comprising a frame and a porous body wound around the outer periphery of the support frame.

Further, in addition to the structure of claim 4, the electrode deposition sludge removing device in the electrodeposition coating device according to claim 5 is characterized in that an opening is formed in the upper half of the support frame. To do.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of an electrodeposition coating apparatus, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is an electrode case. It is an expansion perspective view.

As shown in FIGS. 1 and 2, a car body of an automobile, which is an object to be coated W, is provided above an electrodeposition tank 1 in which an electrodeposition paint containing a polar liquid of lactic acid and formic acid as a solvent is stored. Is mounted on a hanger 2 and an overhead conveyor 3 for immersing the hanger 2 in the electrodeposition paint is provided. A pair of side electrodes 4, 4 are provided along the left and right inner side walls of the electrodeposition tank 1, and a bottom electrode 5 is provided along the inner bottom wall of the electrodeposition tank 1. The hanger 2 of the overhead conveyor 3 is connected to the negative pole of the rectifier 6, whereby the object W to be coated is negatively charged so as to adsorb the positively charged paint particles. On the other hand, the side electrodes 4, 4 and the bottom electrode 5 are connected to the positive electrode of the rectifier 6 in order to attract the negative polar liquid ions contained in the electrodeposition paint.

The outer periphery of the side electrodes 4, 4 is a container-shaped diaphragm device 7, 7 made of a diaphragm (ion exchange membrane) that allows ions and low molecules to pass but does not allow polymers such as paint particles to pass.
Covered with. The insides of the diaphragm devices 7 and 7 are connected to a polar liquid tank 9 through a polar liquid discharge pipe 8, and the polar liquid tank 9 is a pump 10
The diaphragm device 7 via the polar liquid supply pipe 11 with
7 is connected inside. A pure water tank 15 is connected to the polar liquid tank 9 via a pure water supply pipe 14 having a motor valve 13 driven by an actuator 12. A signal from an ionization meter 16 provided in the polar liquid tank 9 is input to a controller 17, and the motor valve 13 is controlled to open and close by a command from the controller 17.

Overflow tank 1 connected to electrodeposition tank 1
A first electrodeposition coating material circulation pipe 22 having a pump 19, a filter 20 and a flow rate adjusting valve 21 interposed therein is connected to 8, and the first electrodeposition coating material circulation pipe 19 is located near the bottom of the electrodeposition tank 1. It is connected to the first riser 23 having a large number of nozzles 23 ₁ ...

As will be apparent by referring also to FIG.
The bottom electrode 5 arranged at the bottom of the electrodeposition tank 1 is housed inside an electrode case 24 made of a non-conductive material. The electrode case 24 includes a support frame 25 having a substantially cylindrical shape,
The end wall 25 ₁ formed at one end of the support frame 25 has a second
The electrodeposition paint circulation pipe 26 is connected, and the other end is the electrodeposition tank 1
It is opened inside. A large number of openings 25 ₂ are formed in the upper half of the peripheral wall of the support frame 25, and 50 μm are formed outside the openings
A porous body 27 made of a mesh of about 500 μm mesh is wound.

A pump 28 and a filter 29 are installed in the second electrodeposition paint circulating pipe 26, one end of which is connected to the electrode case 24.
And a flow rate adjusting valve 30 are interposed, and the other end is provided with a large number of nozzles 31 ₁ ... arranged near the bottom of the electrodeposition tank ₁ .
Connected to the second riser 31 having

Next, the operation of the first embodiment of the present invention having the above construction will be described.

The polar liquid in the diaphragm device 7, 7 whose ionization degree has been increased by attracting the polar liquid ions contained in the electrodeposition paint to the side electrodes 4, 4 overflows from the diaphragm device 7, 7. Is supplied to the polar liquid tank 9. The ionization degree of the polar liquid in the polar liquid tank 9 is detected by the ionization meter 16, and the controller 17 adjusts the opening degree of the motor valve 13 based on the output thereof. As a result, the ionization degree of the polar liquid is adjusted to an appropriate value by the pure water supplied from the pure water tank 15, and the ionization-adjusted polar liquid is separated by the pump 10 provided in the polar liquid supply pipe 11 into the diaphragm device 7. , 7 back inside. In this way, by discharging the polar liquid ions in an amount commensurate with the amount of paint particles applied to the object W to be coated, the pH of the electrodeposition paint in the electrodeposition tank 1 is maintained at a constant value, It is possible to prevent the defect that the defective skin occurs on the surface of the object W.

On the other hand, the electrodeposition paint in the overflow tank 18 is sucked by the pump 19 provided in the first electrodeposition paint circulation pipe 22, passes through the filter 20, and is filtered to remove sludge and other impurities. , Are jetted from the nozzle 23 ₁ of the first riser 23 into the electrodeposition tank 1. This allows
Stirring of the electrodeposition paint in the electrodeposition tank 1 prevents the pigment components in the electrodeposition paint from settling.

By the way, sludge is deposited on the surfaces of the side electrodes 4, 4 and the bottom electrode 5 which are in contact with the electrodeposition paint, and this sludge eventually comes from the surfaces of the side electrodes 4, 4 and the bottom electrode 5. Peel inside. At this time, the side electrodes 4,
Since 4 is separated from the inside of the electrodeposition tank 1 by the diaphragm devices 7 and 7, there is no possibility that the sludge separated from the side electrodes 4 and 4 will be mixed with the electrodeposition paint and adhere to the object W to be coated. .

On the other hand, the sludge separated from the bottom electrode 5 having no diaphragm device may be mixed in the electrodeposition paint in the electrodeposition tank 1, but the electrode around which the bottom electrode 5 is wrapped with the porous body 27 is used. It is covered with the case 24, and moreover, the electrode case 2
Since the electrodeposition paint in 4 is sucked by the pump 28 provided in the second electrodeposition paint circulation pipe 26, the sludge separated from the bottom electrode 5 does not diffuse into the electrodeposition tank 1 and the second It flows into the electrodeposition paint circulation pipe 26. The sludge sucked together with the electrodeposition paint is filtered by the filter 29, and only the clean electrodeposition paint is ejected from the nozzles 31 ₁ of the second riser 31 and returned to the electrodeposition tank 1.

As described above, the sludge separated from the bottom electrode 5 which is a bare electrode is collected by the filter 29 provided in the second electrodeposition paint circulating pipe 26 without being diffused in the electrodeposition tank 1. Therefore, it is possible to reliably prevent the occurrence of coating failure due to the sludge adhering to the object W to be coated. Further, by providing the opening 25 ₂ in the upper half portion of the support frame 25 of the electrode case 24, the electrodeposition coating material can be positively sucked from the upper layer portion of the electrodeposition tank 1 to enhance the stirring effect. .

Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, the flow rate adjusting valve 32 is provided from the position downstream of the filter 29 of the second electrodeposition paint circulating pipe 26.
The branch pipe 33 having a branch is branched, and the branch pipe 33 is connected to the end face of the support frame 25 of the electrode case 24 on the opposite side of the connection portion of the second electrodeposition paint circulating pipe 26. The other structure is the same as that of the first embodiment.

Thus, according to the second embodiment, not all of the electrodeposition paint that has passed through the filter 29 of the second electrodeposition paint circulation pipe 26 is supplied to the second riser 31, but a part thereof. Of the sludge, which is not completely removed by the filter 29, passes through the filter 29 again by refluxing the sludge into the electrode case 24 through the branch pipe 33, thereby improving sludge removal efficiency. Can be made.

Next, a third embodiment of the present invention will be described with reference to FIG.

In the third embodiment, the overflow tank 18 is used.
A first electrodeposition paint circulating pipe 22 extending from the pump, and a pump 19 and a filter 2 installed in the first electrodeposition paint circulating pipe 22.
0 is eliminated, and instead, the upstream position of the pump 28 of the second electrodeposition paint circulation pipe 26 is branched and connected to the overflow tank 18. Then, the second electrodeposition paint circulation pipe 2
6 to branch the branch pipe 34, the branch pipe 34 through the flow rate adjusting valve 21 to the first riser 23, the second
The electrodeposition paint circulation piping 26 is connected to the second riser 31 via the flow rate adjusting valve 30, respectively. The other structure is the same as that of the first embodiment.

Thus, according to the third embodiment, the electrodeposition paint is sucked in the overflow tank 18 and the electrode case 24 is used.
A common second electrodeposition paint circulation pipe 2 for sucking the electrodeposition paint inside
Since it is circulated through the first riser 23 and the second riser 31 via the pump 28 and the filter 29 provided in FIG. 6, the first electrodeposition paint circulation pipe 22 and the pump 19 installed therein.
Also, the number of parts can be reduced by eliminating the filter 20.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

The fourth embodiment is the same as the second embodiment and the third embodiment.
In combination with the embodiment, the branch pipe 33 connected to the opposite end face of the electrode case 24 is further branched from the downstream side where the branch pipe 34 connected to the first riser 23 is branched from the second electrodeposition paint circulation pipe 26. It is a thing.

Thus, according to the fourth embodiment, it is possible to combine the effects of the second and third embodiments.

Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design changes can be made.

For example, the porous body 27 wound around the support frame 25 of the electrode case 24 may be any one as long as it allows the passage of the electrodeposition paint and prevents the passage of the sludge. Etc. can be used. Also, the bottom electrode 5
In addition, when some of the plurality of side electrodes 4 and 4 are bare electrodes, an electrode case may be attached to the side electrodes to prevent sludge diffusion.

[0035]

As described above, according to the invention as set forth in claim 1, electrode deposition is allowed by allowing passage of the electrodeposition paint at least around the electrodes arranged along the bottom wall of the electrodeposition tank. The non-conductive electrode case that prevents the passage of sludge is covered, and the electrodeposition paint sucked from the electrode case by a pump is passed through the filter and then returned to the electrodeposition tank to separate the electrode from the electrode. It is possible to collect sludge with a filter and prevent it from diffusing into the electrodeposition tank. As a result, it is possible to prevent the problem that the electrode-precipitated sludge in the electrodeposition coating material adheres to the object to be coated and coating failure occurs.

According to the invention described in claim 2,
In addition to the effect of the invention of claim 1, since the electrodeposition coating material circulation pipe is connected to the riser provided in the electrodeposition tank, the electrodeposition coating material in the electrodeposition tank is agitated by the electrodeposition coating material ejected from the riser. However, sedimentation of the pigment component can be prevented.

According to the invention described in claim 3,
Since the branch pipe branched from the filter downstream position of the electrodeposition paint circulation pipe was opened in the electrode case, the electrodeposition paint containing electrode deposition sludge effectively passed through the electrodeposition paint circulation pipe filter multiple times. Purified.

According to the invention described in claim 4,
Since the electrode case is composed of the cylindrical support frame having a large number of openings and the porous body wound around the outer periphery of the support frame, it is possible to effectively prevent the diffusion of the electrode-precipitated sludge separated from the electrode while preventing the diffusion of electricity. The electrodeposition paint can be guided to the electrodeposition paint circulation pipe.

According to the invention described in claim 5,
By forming the opening in the upper half of the support frame, the electrodeposition coating in the upper layer of the electrodeposition tank can be positively sucked to enhance the stirring effect of the electrodeposition coating.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an electrodeposition coating apparatus according to a first embodiment.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an enlarged perspective view of an electrode case.

FIG. 4 is an enlarged view of a main part of the electrodeposition coating apparatus according to the second embodiment.

FIG. 5 is an enlarged view of a main part of an electrodeposition coating apparatus according to a third embodiment.

FIG. 6 is an enlarged view of a main part of an electrodeposition coating apparatus according to a fourth embodiment.

[Explanation of symbols]

1 Electrodeposition Tank 4 Side Electrode (Electrode) 5 Bottom Electrode (Electrode) 24 Electrode Case 25 Support Frame 25 ₂ Opening 26 Second Electrodeposition Paint Circulation Piping (Electrodeposition Paint Circulation Piping) 27 Porous Body 28 Pump 29 Filter 31 Riser 33 Branch pipe W Object to be coated (electrode)

Claims (5)

[Claims] 1. An electrode (W) to be coated is immersed in an electrodeposition tank (1) in which an electrodeposition paint is stored, and the other electrode is formed along the side wall and bottom wall of the electrodeposition tank (1). An electrodeposition coating apparatus for arranging electrodes (4,5) and applying a DC voltage to the one and the other electrodes (W, 4, 5) for electrodeposition coating of an object to be coated, at least an electrodeposition tank The periphery of the electrode (5) arranged along the bottom wall of (1) is covered with a non-conductive electrode case (24) which allows the passage of the electrodeposition paint and prevents the passage of the electrode deposition sludge. The electrodeposition paint containing the electrode precipitation sludge sucked by the pump (28) from the electrode case (24) is passed through the filter (29) to filter the electrode precipitation sludge, and then returned to the electrodeposition tank (1). Characteristic,
Removal method of electrode sludge in electrodeposition coating equipment. 2. An object to be coated immersed in an electrodeposition tank (1) in which an electrodeposition coating material is stored is used as one electrode (W), and the other electrode is formed along the side wall and bottom wall of the electrodeposition tank (1). An electrodeposition coating apparatus for disposing electrodes (4, 5) and applying a DC voltage to the one and the other electrodes (W, 1, 2) for electrodeposition coating of an object to be coated, at least an electrodeposition tank A non-conductive electrode case (24) which is provided so as to cover the periphery of the electrode (5) arranged along the bottom wall of (1) and allows the passage of the electrodeposition coating composition and prevents the passage of electrode deposition sludge. ) And an electrodeposition paint circulation pipe (26) having one end opened in the electrode case (24) and the other end connected to a riser (31) provided in the electrodeposition tank (1)
A pump (28) provided in the electrodeposition paint circulation pipe (26) for sucking and supplying the electrodeposition paint containing electrode deposition sludge in the electrode case (24) to the riser (31); 28) A filter (29) which is provided on the downstream side of the electrode (28) for filtering electrode-precipitated sludge, and which is used for removing electrode-precipitated sludge in an electrodeposition coating apparatus. 3. The branch pipe (33) branched from the position downstream of the filter (29) of the electrodeposition paint circulation pipe (26) is opened in the electrode case (24). Electrode deposition sludge removal equipment in the electrodeposition coating equipment of. 4. An electrode case (24) has a cylindrical support frame (25) having a large number of openings (25 ₂ ), and a porous body (27) wound around the outer periphery of the support frame (25). An electrodeposition sludge removing device in an electrodeposition coating device according to claim 2 or 3, wherein 5. An opening (25) in the upper half of the support frame (25).
₂ ) is formed, The removal device of the electrode precipitation sludge in the electrodeposition coating apparatus of Claim 4 characterized by the above-mentioned.