JPH01136994A - Method for electrodeposition-coating automobile body - Google Patents

Abstract

PURPOSE:To form a coating film free of stage difference on an automobile body without using a special device by completely dipping the body in an electrodeposition tank to coat the body, and then sending out the body from the tank while continuing the current application at the time of electrodeposition-coating the body by batch equipment. CONSTITUTION:The automobile body W turned sideways is lowered and completely dipped in the electrodeposition tank 1, and then an electric current is applied. The body W is then oscillated several times by the rotation of a jig within the specified electrodeposition time to drive off the air accumulated in the recess of the body W, and the entire surface of the body W is electrodeposition-coated. The body W still turned sideways is raised close to the electrodeposition soln. surface, and then placed in a horizontal position. The horizontal body W is raised at the low speed of about 20-40mm/sec while continuing current application, and sent out from the tank in about 30sec-1min. By this method, the lower part of the body is efficiently electrodeposition-coated while being sent out from the tank, the coating film on the lower part of the body is thickened, and steps are not formed on the side of the body.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electrodeposition coating method using batch-type electrodeposition coating equipment in which an automobile body is moved up and down in a fixed position into and out of an electrodeposition tank. .

(Prior art) Conventionally, when performing electrodeposition painting using batch-type equipment, as shown in Japanese Patent Publication No. 44-3111, electricity is applied to the entire surface of the car body by applying electricity while the car body is completely immersed in an electrodeposition bath. After painting, it is common practice to remove the vehicle from the tank with the power turned off.

However, with this method, it is necessary to increase the immersion time in order to form the desired thickness of the paint film on the lower part of the car body, which requires high rust prevention properties, which may result in an unnecessarily large amount of paint film on the upper part of the car body. There was a problem with it being wasted.

Also, although it does not use batch-type equipment,
According to Japanese Patent No. 0-46897, as shown in FIG. 5, the car body W is completely immersed in the first half of the long electrodeposition #fJa in the transport direction of the car body W, and the entire surface of the car body is electrocoated. The upper part of the car body is exposed from the '1t1a liquid level in the latter half of the deposition tank a, and the car body W is held in this state for a certain period of time. During that time, electricity is applied to apply electrodeposition coating only to the lower part of the car body. A device with a thicker film is known.

(Problems to be Solved by the Invention) In the above-mentioned method, when the lower part of the car body is electrocoated, a step is formed in the coating film at the boundary with the electrodeposition liquid level on the side surface of the car body, resulting in poor appearance.

In order to solve this problem, Japanese Patent Application Laid-Open No. 60-46398 discloses spraying washing water at the boundary with the liquid surface during electrodeposition coating on the lower part of the car body, and Japanese Patent Application Laid-Open No. 80-50198.
According to the publication, a shielding plate is placed near the boundary with the liquid surface to suppress electrodeposition at the boundary, but this method does not allow the spray equipment, shielding plate, etc. There is a problem that a device for eliminating the level difference is required, which increases the cost.

SUMMARY OF THE INVENTION In order to solve these problems, it is an object of the present invention to provide a batch-type electrodeposition coating method that does not require a special device for eliminating level differences.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an electrocoating system using batch type electrocoating equipment in which the body of a car is moved up and down in a fixed position to enter and exit the electrocoat tank. In the coating method, the car body is completely immersed in an electrodeposition bath and the entire surface of the car body is coated with electrodeposition, and then the car body is gently lifted up in an almost horizontal position without stopping midway while the electricity is continued. It is characterized by having a tank.

(Function) In order to continue energizing the car body and take it out of the tank, electrodeposition coating is applied even while the car body is being taken out of the tank.In this case, as the car body rises, the area of the car body that is immersed in the electrolyte liquid and the area of the electrodes in the tank. The relative polarity ratio, which is the ratio between Become.

Furthermore, since the car body is raised without stopping midway, there is no difference in level on the paint film on the side of the car body.

(Example) Referring to FIGS. 1 to 3, (1) shows an electrodeposition tank in which a large number of electrodes (2) are arranged in a row on the side surface of the tank, and the electrodeposition tank (1) is A pair of columns (3) (3) are erected at the front and rear of the arrangement section, and a pair of elevating frames are provided on both columns (3) (3) that can be raised and lowered along rails (3a) fixed thereto. (4) (4
), and the supporting legs (4a) are suspended from the tip portions of each lifting frame (4) facing the electrodeposition bath (1), and both lifting frames (4) are supported.
) (4) The lower end of the support leg (4a) (ia) is attached to the vehicle body W.
A jig (5) supporting the is rotatably supported around an axis (5a) in the vehicle length direction, and each elevating frame (4) is equipped with a double-speed rack and pinion type double-speed mechanism using a cylinder (6) as a driving source. Mechanism (7
), and one lifting frame (4) is attached to the jig (5).
Rotation is provided via a chain (9) by a motor (8) mounted on the motor (8).

Then, the car body W is attached to an electrodeposition bath (1) using a hanger (not shown).
), the lifting frame (4) is raised to allow the jig (5) to receive the vehicle body W, and then the lifting frame (4) is raised to receive the vehicle body W.
4) The vehicle body W was immersed in the electrodeposition tank (1) by lowering the step (4), and the entire apparatus constituted a batch type electrodeposition coating equipment.

Next, the procedure for electrodeposition coating using the above-mentioned equipment will be explained with reference to FIG.

First, by rotating the jig (5), the vehicle body W is lowered in a rolled-over position with the vehicle width direction facing the vertical direction (Fig. 4(a)).
When the car body W is completely immersed in the electrodeposition bath (1), electricity is started (Fig. 4 (b)), and then the electricity is turned on for a predetermined time in order to eliminate the air accumulated in the recesses of the car body W. (for example, 1 minute and 30 seconds), the vehicle body W is rocked several times by the rotation of the jig (5) (FIG. 4(C) to (h)), and the entire surface of the vehicle body W is electrocoated.

Next, the vehicle body W is raised in a rollover position to near the electrodeposition liquid level, and then the vehicle body W is returned to a horizontal position (Figure 4 (iHj)).
While continuing to energize, raise the car body at a slow speed of 20 mm/sec to 40+ m/sec (Fig. 4 (k)), 30 seconds to
After allowing the tank to exit the tank for about 1 minute, turn off the power (
Figure 4 UD).

According to this, as explained in the section of the above-mentioned effect, the electrodeposited coating is efficiently applied to the lower part of the car body during tank removal, the paint film on the lower part of the car body becomes thicker, and the paint film on the sides of the car body becomes uneven. Not at all.

It is also possible to return the vehicle body W to the horizontal position and raise it from the state shown in FIG. 4 (1'0);
In contrast, in the above embodiment, when the roof is exposed above the electrolyte surface, it receives a large amount of resistance.However, according to the above embodiment, when the roof is swung from the state shown in FIG. It is advantageous because it is exposed above the liquid surface in a cutting manner, allowing the vehicle body W to exit the tank smoothly.

(Effects of the Invention) As described above, according to the present invention, by allowing the car body to be taken out of the tank while being energized, it is possible to form a thick coating film on the lower part of the car body without creating a step on the coating film on the side surface of the car body. This has the effect of improving productivity, eliminating the need for a special device for eliminating level differences, reducing equipment costs, and significantly improving productivity.

[Brief explanation of the drawing]

Fig. 1 is a cutaway side view of an example of a batch-type electrodeposition coating equipment used to carry out the method of the present invention, Fig. 2 is a plan view thereof, and Fig. 3 is a cross-sectional view taken along the line ■-■ in Fig. 1. Figures (a) to ω are process diagrams showing the procedure for coating electric tubes, and Figure 5 is a side view of the conventional technique.

Claims (1)

[Claims] In an electrodeposition painting method that uses batch-type electrodeposition painting equipment that moves the car body up and down in a fixed position into and out of the electrodeposition tank, the car body is completely immersed in the electrodeposition tank and the entire surface of the car body is electrodeposited. A method for electrocoating an automobile body, which is characterized in that after coating, the vehicle body is gradually lifted up and taken out from the tank in a substantially horizontal position without stopping while the current is being applied.