JPH0526879B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an electrode in an electrodeposition paint and applies a DC voltage between the electrode and the object to be coated supported by an object supporter to form a coating film. The present invention relates to an electrodeposition coating method and a coating device therefor.

[Conventional technology]

In recent years, electrodeposition coating has been widely practiced as a unique coating method. In the electrodeposition coating apparatus used in this case, the paint tank is formed in a boat shape, and the electrodeposition paint is accommodated inside the tank. Further, a conveyor is installed above the paint tank in the longitudinal direction, and a power supply rail connected to one pole of a voltage supply source is installed parallel to the conveyor only above the paint tank.

Further, the conveyor is provided with a plurality of article supports at intervals, which support the article to be coated while contacting the power supply rail and carry the article into the electrodeposition paint in the paint tank. Further, a plurality of electrodes connected to the other pole of the voltage supply source are provided in the electrodeposition paint in the paint tank.

When forming an electrocoating film on the surface of the object to be coated, the object to be coated is supported on the article support and immersed in the electrodeposition paint in the paint tank while the article support is in contact with the power supply rail. . Along with this, a direct current voltage is applied between the object to be coated and the electrodes in the electrodeposition paint, so that an electrodeposition coating film is formed on the surface of the object to be coated.

[Problem to be solved by the invention]

However, in such electrodeposition coating methods, the electrical resistance of the electrodeposition coating film formed on the surface of the object increases due to electroosmosis, so once the coating thickness reaches a certain level, It is difficult to form an electrodeposition coating film, and due to the coverage property that is one of the characteristics of electrodeposition coating, it is difficult to form an electrodeposition coating film on the area where the existing electrodeposition coating film is formed, The fact is that film formation occurs only in certain areas.

For this reason, although it is excellent in uniformly forming an electrodeposition coating film on the surface of the object to be coated,
There is a problem in that it is not possible to make the electrodeposition coating film thick only on specific parts of the object to be coated.

Therefore, this invention makes it possible to arbitrarily set the voltage of the electrode in the area where a thick film is required independently of other electrodes, so that only a specific part of the electrodeposited film can be coated with a thick film. purpose.

[Means to solve the problem]

Therefore, in the electrodeposition coating method of the present invention, the object to be coated supported by the object support is used as one electrode.
The other electrode is immersed in the electrocoating paint in the paint tank provided inside, and a predetermined DC voltage from a voltage supply source is applied between the two electrodes to form an electrocoating film on the surface of the object to be coated. In the electrodeposition coating method, a second voltage supply source is provided near a portion of the object to be coated that requires thick film coating, while an auxiliary electrode having the same polarity as the other electrode and opposite to the object to be coated is provided. The coating is applied by applying a DC voltage higher than the predetermined DC voltage.

Further, the electrodeposition coating apparatus of the present invention includes a conveyor installed above the paint tank in the longitudinal direction containing the electrodeposition paint, and a power supply connected to one pole of the voltage supply source parallel to the conveyor. A rail is constructed, and a plurality of article supports are provided at intervals on the conveyor to support the object to be coated and carry it into the electrodeposition paint while contacting the power supply rail, and the electrodeposition paint in the paint tank is further provided with a plurality of article supports at intervals. In an electrocoating apparatus having an electrode connected to the other type of voltage supply source, a second power supply rail is installed parallel to the conveyor;
This second power supply rail is connected to the same polarity as the other electrode of the voltage supply source of a second voltage supply source separate from the voltage supply source, and further, the second power supply rail is connected to the same polarity side as the other electrode of the voltage supply source, and An auxiliary electrode that is movable in contact with the second power supply rail is disposed near the area that requires thick film paint.

[Effect]

By the above-mentioned means, an auxiliary electrode opposite to the object to be coated is provided near a portion of the object to be coated that requires thick film coating, and a second voltage supply source is applied to the auxiliary electrode to apply a coating layer to the object. By applying a DC voltage larger than a predetermined DC voltage depending on the required thickness of the electrode, the electrophoretic action becomes more active in this area than in other areas, promoting the formation of an electrodeposition coating film. ,
A thick coating film is formed on a predetermined portion of the object to be painted.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the electrodeposition coating method and its coating apparatus according to the present invention will be explained in detail based on the drawings.

(First Embodiment) FIG. 1 shows a side sectional view of a first embodiment of an electrodeposition coating apparatus according to the present invention.

In FIG. 1, reference numeral 1 denotes a paint tank made of a metal material in the shape of a boat. Inside the paint tank 1, a plurality of electrode rods 2 made of a metal material are arranged with the sides at the bottom. and one end of it is connected to conductor 3.
a to the anode side of the voltage supply source 4. A cationic electrodeposition paint M is housed inside the paint tank 1.

Further, a conveyor 5 is installed above the paint tank 1 in the longitudinal direction, and is sloped sequentially downward from the input side of the paint tank 1, is horizontal above the paint tank 1, and is horizontal on the output side. They are arranged so as to be slanted upward in sequence. An insulating member (not shown) is provided above the conveyor 5 in parallel with the conveyor 5.
A power supply rail 6 is installed through the paint tank 1, and is installed only above the paint tank 1, and is connected to the cathode side of the voltage supply source 4 by a conductive wire 3b.

Further, a plurality of conductive article supports 7 are suspended from the conveyor 5 at appropriate intervals for supporting automobile bodies W as objects to be painted. This article support 7 has frame bodies 7a formed in a gate shape arranged in the front and rear so as to hold the automobile body W, and the frame bodies 7a are connected by horizontal pillars 7b, and the central part of the horizontal pillars 7b A support member 7d, which is provided with a current collector 7c that contacts the power supply rail 6 and supplies power while rotating, is fixed to the support member 7d.

Further, two support members 8a and 8b are arranged with a gap above the power supply rail 6, and power supply rails 9a and 9b are respectively provided above them with an insulating member (not shown) interposed therebetween. It is being One power supply rail 9a is connected to the anode side of the voltage supply source 4 by a conductor 3c, and the other power supply rail 9b is connected to the anode side of the voltage supply source 4 by a conductor 3d. Power supply rails 9a, 9
b has the same polarity as the electrode plate 2 provided inside the paint tank 1.

Furthermore, two auxiliary electrodes 10a and 10b are arranged vertically in the electrodeposition paint M in the paint tank 1, and the upper auxiliary electrode 10a is connected to one power supply rail 9.
The lower auxiliary electrode 10b is provided on a support 12a having a collector 11a that rotates and supplies power while contacting the other power supply rail 9b, and the support 12b has a collector 11b that rotates and supplies power while contacting the other power supply rail 9b.
It is set in. And both auxiliary electrodes 10a,
10b is disposed at a portion of the automobile body W that requires thick film coating, and is adapted to move along with the automobile body W.

A method for forming an electrodeposition coating film on the surface of an automobile body W, which is an object to be coated, using the electrodeposition coating apparatus configured as described above will be described.

First, the automobile body W is supported on the article support 7 suspended from the conveyor 5, and auxiliary electrodes 10a are placed above the ceiling portion Wa and near the floor portion Wb of the automobile body W that requires thick film coating. 10b are respectively arranged. Thereafter, the conveyor 5 is operated and driven in the direction of the arrow shown in FIG.
When the article is conveyed to the power supply rail 6, the current collector 7c of the article support 7 comes into contact with it while rotating, and a cathode potential is applied to the automobile body W.

Subsequently, as the conveyor 5 moves, a part of the automobile body W is carried into the electrocoating paint M charged on the anode side and electrically connected. As the car body W is immersed in the electrodeposition paint M, the voltage gradually increases, and when the car body W is completely immersed in the electrodeposition paint M, the voltage reaches a predetermined value. , the electrodeposition coating process is carried out. In addition, auxiliary electrodes 10a and 10b are arranged near the parts of the ceiling Wa and the floor Wb that require thick film coating, and the current collectors 11a and 11b are provided with the respective supports 12a and 12b. contacts each power supply rail 9a, 9b sequentially. At that time, each auxiliary electrode 10a, 10b becomes an anode potential, and the ceiling part Wa
And the electrophoretic action in the vicinity of the floor Wb becomes active, promoting the formation of an electrodeposition coating film.

In this state, a DC voltage is applied for a certain period of time,
Automobile body W on which a predetermined electrodeposition coating film is formed
are removed from the electrodeposition paint M, and the auxiliary electrodes 10a and 10b disposed near the ceiling Wa and the floor Wb are removed. Then, the article support 7 separates from the power supply rail 6, and the application of voltage to the automobile body W is interrupted.

Thus, the predetermined electrodeposition coating film and ceiling area
The automobile body W, which has been coated with a thick film on Wa and the floor Wb, is conveyed by the conveyor 5 together with the article support 7 through post-processing processes such as a water washing process and a drying process (not shown).
The electrodeposition coating is then transported to the final stage and completed as a complete electrodeposition coating.

(Second Embodiment) FIG. 2 shows a side sectional view of a second embodiment of the electrodeposition coating apparatus according to the present invention.

This second embodiment is the same as the first embodiment in many respects, and the same parts are given the same numbers and their explanations will be omitted and only the differences will be described.

The difference in the second embodiment is that there is a second voltage supply source separate from the voltage supply source 4 connected to the electrode rod 2 in the electrodeposition paint M and the power supply rail 6 near the paint tank 1. Two voltage supply sources 20 and 21 are arranged, and the conductor 3c of the power supply rail 9a is connected to the anode side of one voltage supply source 20, and the conductor 3c of the power supply rail 9b is connected to the anode side of the other voltage supply source 21. It is located where the 3d is connected.

Therefore, it is possible to apply an anodic potential to each auxiliary electrode 10a, 10b separately, and by changing the application of the anode voltage to each auxiliary electrode 10a, 10b, it is possible to apply thick film coating to areas that require thick coating. The thickness of the electrodeposited film can be adjusted freely.

(Third Embodiment) FIG. 3 shows a side sectional view of a third embodiment of the electrodeposition coating apparatus according to the present invention.

This third embodiment is the same as the first embodiment in many respects, and the same parts are given the same numbers and their explanations will be omitted and only the differences will be described.

The difference in the third embodiment is that an insulating member (not shown) is interposed on the upper part of each support member 8a, 8b, and one power supply rail 9c, 9d is provided, respectively.
The additional power supply rails 9c and 9d are additionally provided.
are coated with electrodeposited paint M by conducting wires 3e and 3f, respectively.
It is connected to the anode side of the voltage supply source 4 which is connected to the electrode plate 2 inside and the power supply rail 6, and is separately provided to the other two power supply rails 9a and 9b by conducting wires 3c and 3d, respectively. Second voltage supply source 30
It is connected to the anode side of the

This makes it possible to apply anodic potential to each of the auxiliary electrodes 10a and 10b in two stages from the two voltage supply sources 4 and 30, smoothing the surface of the electrodeposited film formed on the thick film coating area. can be converted into

(Fourth Embodiment) FIG. 4 shows a side sectional view of a fourth embodiment of the electrodeposition coating apparatus according to the present invention.

This fourth embodiment is the same as the third embodiment in many respects, and the same parts are given the same numbers and their explanations will be omitted and only the differences will be described.

The difference in the fourth embodiment is that there is a second voltage supply source separate from the voltage supply source 4 connected to the electrode rod 2 in the electrodeposition paint M and the power supply rail 6 near the paint tank 1. Four voltage supply sources 40, 41, 4
2 and 43, and the conductor 3c of the power supply rail 9a is connected to the anode side of the first voltage supply source 40, and the conductor 3d of the power supply rail 9b is connected to the anode side of the second voltage supply source 41. Furthermore, the conductor 3f of the power supply rail 9d is connected to the anode side of the second voltage supply source 42, and the conductor 3e of the power supply rail 9c is connected to the anode side of the fourth voltage supply source 43.

As a result, it is possible to apply an anode potential to each auxiliary electrode 10a, 10b separately, and by changing the application of anode voltage to each auxiliary electrode 10a, 10b, it is possible to apply thick film coating to areas that require thick coating. The thickness of the electrodeposited film can be adjusted freely. Also,
Two-stage energization from two voltage supply sources 40, 41, 42, and 43 is possible to apply an anode potential to each of the auxiliary electrodes 10a and 10b, and an electrodeposition coating film is formed in areas where thick film coating is required. The surface of can be smoothed.

In the first to fourth embodiments described above, cationic electrodeposition coating is performed in which the automobile body W as the object to be coated is charged as a cathode, and the electrode rod 2 provided inside the paint tank 1 is charged as an anode. However, the present invention can also be applied to anionic electrodeposition coating, which has the opposite polarity to cationic electrodeposition coating.

〔Effect of the invention〕

As described above, the present invention provides an auxiliary electrode opposite to the object to be coated near a portion of the object to be coated that requires thick film coating, and while this auxiliary electrode is accompanied by the object to be coated, a second Since the electrodeposition coating is performed by applying a DC voltage higher than the predetermined DC voltage from the voltage supply source, it is possible to apply a thick electrodeposition coating only to specific areas that require thick coating. At the same time, DC voltage can be applied independently to the auxiliary electrode, so by changing the application of DC voltage to the auxiliary electrode according to the required thickness of the coating film, it is possible to apply thick film coating to areas that require thick coating. The thickness of the electrodeposited film can be set freely.

In addition, by making the electrodeposition coating film thicker only in specific areas, it is possible to make the electrodeposition coating film thinner in areas that do not require a thicker coating, which reduces the amount of electrodeposition paint used. can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a first embodiment of an electrodeposition coating apparatus according to the present invention. FIG. 2 is a side sectional view showing a second embodiment of the electrodeposition coating apparatus according to the present invention.
FIG. 3 is a side sectional view showing a third embodiment of the electrodeposition coating apparatus according to the present invention. FIG. 4 is a side sectional view showing a fourth embodiment of the electrodeposition coating apparatus according to the present invention. 1... Paint tank, 2... Electrode rod, 4... Voltage supply source, 5... Conveyor, 6... Power supply rail, 7...
Article support, 9a, 9b, 9c, 9d...power supply rail, 10a, 10b...auxiliary electrode, 20,2
1, 30, 40, 41, 42, 43...voltage supply source.

Claims (1)

[Scope of Claims] 1. An object to be painted supported by an object support is immersed in electrodeposition paint in a paint tank with the other electrode set as one electrode, and a voltage supply source is connected between the two electrodes. In an electrodeposition coating method in which an electrodeposition coating film is formed on the surface of an object to be coated by applying a predetermined DC voltage from
The predetermined DC voltage is applied from a second voltage supply source while an auxiliary electrode having the same polarity as the other electrode and opposite to the object to be coated is provided near a portion of the object to be coated that requires thick film coating. An electrodeposition coating method characterized by applying a DC voltage higher than that of the electrodeposition coating method. 2. A conveyor is installed above the paint tank containing electrocoated paint in the longitudinal direction, and a power supply rail connected to one pole of a voltage supply source is installed parallel to this conveyor, and the power supply rail is connected to the conveyor. A plurality of article supports are provided at intervals to support the article to be coated and carry it into the electrodeposition paint while being in contact with the electrodeposition paint, and the other pole of the voltage supply source is connected to the electrodeposition paint in the paint tank. In an electrodeposition coating apparatus provided with connected electrodes, a second power supply rail is installed parallel to the conveyor, and this second power supply rail is connected to a second voltage supply source separate from the voltage supply source. A second power supply rail is connected to the same polarity as the other electrode of the voltage supply source, and is moved in contact with a second power supply rail near a portion of the object to be coated that is immersed in the paint and requires thick film paint. An electrodeposition coating device characterized by being equipped with an auxiliary electrode.