JPH06104919B2 - Electrodeposition coating method for automobile bodies - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrodeposition coating method for an automobile body capable of forming a thick electrodeposition coating film on the lower portion of the vehicle body which requires high rust prevention.

(Prior Art) Conventionally, according to Japanese Patent Laid-Open No. 60-46397, after the vehicle body is completely immersed in the electrodeposition tank and the entire surface of the vehicle body is subjected to electrodeposition coating, the upper part of the vehicle body is exposed from the liquid surface of the electrodeposition tank. It is known that the film is made to come out and only the lower part of the vehicle body is subjected to electrodeposition coating to thicken the coating film at the lower part of the vehicle body.

(Problems to be solved by the invention) By the way, in order to improve the stirring property of the electrodeposition liquid in the electrodeposition tank and prevent the paint from settling, too many electrodes can be arranged on the bottom part of the electrodeposition tank. Instead, many electrodes are arranged on the side surface portion of the electrodeposition tank. Here, in the above-described conventional technology, since the vehicle body is held in a horizontal posture, even if only the lower part of the vehicle body is immersed in the electrodeposition tank. , The current density on the floor of the vehicle is insufficient,
If the dipping time is increased so that the coating on the floor becomes thinner and a sufficient thickness is formed on the floor, the coating on the lower side of the vehicle body becomes too thick and There is a step and the appearance is poor.

The present invention solves such problems and provides an electrodeposition coating method capable of forming a coating film having a sufficient thickness on a floor portion of a vehicle body without generating a step on the coating film on the side surface of the vehicle body. Is its purpose.

(Means for Solving the Problems) In order to achieve the above object, the present invention completely immerses a vehicle body of an automobile in an electrodeposition tank, and in this state, the vehicle body is in a rollover posture in which the vehicle width direction faces the vertical direction. While standing still for a certain period of time, it intermittently oscillates about the vehicle length direction, and when standing still in the overturning position, the floor part of the vehicle body is made to face the electrodes arranged on the side part of the electrodeposition layer to grow the coating film on the floor part. It is characterized by

(Operation) When the vehicle body is in the overturned posture, the floor portion of the vehicle body faces the electrodes arranged on the side surface portion of the electrodeposition tank to increase the current density in the floor portion, and the vehicle body is kept stationary in the overturned posture for a certain period of time to cause the floor to fall. A thick coating film is formed on the part.

Further, when the vehicle body swings, the side surface of the vehicle body faces the electrode on the side surface portion of the electrodeposition tank, and a coating film is formed on the electrode. In this case, the vehicle body is completely immersed in the electrodeposition tank. There is no step on the coating film.

(Example) With reference 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 inside the tank. A pair of columns (3) and (3) are erected in front of and behind the arrangement portion, and rails (3) fixed to the columns (3) and (3) are fixed to the columns.
A pair of elevating frames (4) (4) that can be raised and lowered along a) are supported, and a supporting leg (4a) is hung at the tip of each elevating frame (4) facing the electrodeposition tank (1). And the both elevating frames (4) (4)
A jig (5) for supporting the vehicle body W is rotatably supported around the shaft (5a) in the vehicle length direction at the lower end of the supporting legs (4a) (4a) of each of the elevating frames (4). A rack and pinion type double speed mechanism (7) using a cylinder (6) as a drive source is moved up and down and a chain (9) is mounted on the jig (5) by a motor (8) mounted on one of the lifting frames (4). And the rotation via.

Then, after the vehicle body W is conveyed to a position above the electrodeposition tank (1) by a hanger (not shown), the jigs (5) are made to receive the vehicle body W by raising the elevating frames (4) (4), and then the elevating frame (4) is received. (4) The vehicle body W was immersed in the electrodeposition tank (1) by descending (4), and the batch type electrodeposition coating equipment was configured as a whole.

Next, the work procedure of electrodeposition coating by the above equipment will be described with reference to FIG.

First, the vehicle body W is completely immersed in the electrodeposition tank (1) in a state in which the jig (5) is rotated so that the vehicle width direction is in the vertical direction (FIGS. 4 (a) and (b)). , A certain time after immersion (eg 10
After resting the vehicle body W in the overturning posture, the vehicle body W is slowly swung by turning the jig (5) in the reverse overturning posture for about 20 seconds (see FIG. 4 (c)). ) (D)), and after the vehicle body W has been stationary in this rollover posture for a certain period of time,
To the original overturning posture and remain stationary for a certain period of time (Figs. 4 (e) and (f)). Then, the vehicle body W is swung again in the reverse overturning posture and remains stationary for a certain period of time (Fig. 4 (e)). g) (h)), and after that, the vehicle body W is taken out from the tank in the reverse rollover posture to complete the electrodeposition coating (FIG. 4 (i)).

According to the above method, the coating film is formed on the side surface portion of the vehicle body W when the vehicle body W is rocked, and the floor portion is formed on the electrode (2) on one side of the electrodeposition tank (1) when the vehicle body W is stationary in the rollover posture. A thick coating film is formed facing the floor. A coating film is formed on the roof portion while the roof portion at this stationary time faces the electrode (2) on the opposite side of the electrodeposition tank (1). At this time, the voltage applied to the electrode (2) facing the roof portion is applied. If the current density in the roof portion is reduced by lowering the temperature, it is possible to prevent the film in the roof portion from becoming unnecessarily thick.

Further, by swinging the vehicle body W, the air accumulated in the recess of the vehicle body W is removed, and the entire inner and outer plates of the vehicle body W are electrodeposited.

In the above embodiment, the vehicle body W is taken out in the rollover posture. However, before the tank is taken out, the vehicle body W is placed in a horizontal posture, and the roof portion is raised to a position where it does not come out to the liquid surface. Alternatively, the vehicle body W may be allowed to stand out for a certain period of time, whereby the coating film on the lower portion of the side surface of the vehicle body W can be formed thick without any step.

(Effects of the Invention) As described above, according to the present invention, the coating film on the side surface of the vehicle body can be thickly formed on the floor portion without causing a step difference, and the air is eliminated by the swinging of the vehicle body. It is possible to prevent the occurrence of coating defects due to the accumulation of air, and it is possible to obtain good electrodeposition coating.

[Brief description of drawings]

FIG. 1 is a cutaway side view of an electrodeposition coating facility used for carrying out the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a cross-sectional view taken along line III-III of FIG. 1, and FIG. (I) is a process diagram showing a work procedure of electrodeposition coating. W: car body, (1) ... electrodeposition tank

Claims (1)

[Claims] 1. A vehicle body of an automobile is completely immersed in an electrodeposition tank, and in this state, the vehicle body is stationary in a rollover posture in which the vehicle width direction faces the vertical direction for a certain period of time and intermittently oscillates about the vehicle length direction. An electrodeposition coating method for an automobile body, wherein the floor portion of the vehicle body is made to face an electrode arranged on a side surface portion of the electrodeposition tank to grow a coating film on the floor portion when the vehicle is stationary in a rollover posture.