JPH072999B2 - Electrodeposition coating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application The present invention relates to an electrodeposition coating method capable of preventing the generation of hash marks.

b. Conventional technology While moving the object to be coated into the electrodeposition tank containing the paint,
In the continuous coating method, in which the electrodeposition coating takes several minutes as in the case of electroplating, the object to be coated is hung on the hanging tool of the overhead conveyor and the tank is energized at a constant conveyor speed for transfer. The format is adopted.

The conveyor speed of mass-produced electrodeposition coating lines such as automobiles is around 4 m / min, and the vertical speed at the time of entering the tank, and the descending inclination angle of the conveyor is about 30 ° (about 45 ° on the exit side). Then, it becomes 2 m / min, which is not a problem than 1 to 1.5 m / min. However, in the case of limited small-volume production models,
Conveyor speed may be reduced considerably, and if it is 1.5m
/ min, the vertical velocity is 0.75
It becomes m / min and causes a problem.

In addition, in the case of overseas production, in order to reduce the equipment cost, a very small electrodeposition tank, in an extreme case, only one car body can be put in, so naturally the conveyor speed becomes low and there is a problem. It becomes a factor of the point.

FIG. 3 abc shows various modes of electrodeposition coating methods.

In this case, as shown in FIG. 3a, a plurality of objects 101 to be coated are hung and conveyed on the conveyor 100, and generally immersed in the paint 103 of the electrodeposition tank 102 of several tens of meters long even for several tens of meters. However, there is no problem in the normal state where the electrodeposition coating is performed, or when the single object 101 to be coated is electrodeposited in the electrodeposition tank 102 as shown in FIG.

However, as shown in FIG. 3C, the objects 101 to be coated are spaced apart from each other so that when one object 101 to be coated exits from the electrodeposition tank 102, the other object 101 to be coated enters. In that case,
At the time of entering the tank, a coating film defect (pinhole-shaped depression) called a hash mark (or step) is formed on a part of the object to be coated 101.

In the case of FIG. 3a, since there are many objects 101 to be coated, current does not concentrate on the object 101 to be coated, and in the case of FIG. 3b, soft start can be performed. Therefore, the generation of hash marks can be prevented.

c. Problems to be Solved by the Invention However, in the case as shown in FIG. 3c, the coating film is not formed on the article 101 to be coated when entering the tank, so that the resistance is low,
Since a large amount of current flows, a hash mark is generated.

It is an object of the present invention to solve the above problems and provide an electrodeposition coating method capable of preventing the generation of hash marks.

d. Means for Solving the Problems The present invention is an electrodeposition method for carrying out electrodeposition coating by immersing an object to be coated hung on a main conveyor through a suspending tool and immersing it in an electrodeposition tank containing a paint. In the coating method, in the section including the range in which the object to be coated enters the electrodeposition tank, an auxiliary conveyor that can be transported at a higher speed than the main conveyor is installed side by side with the main conveyor, and the object to be coated only when entering the tank. Transfer from the main conveyor to the auxiliary conveyor, and increase the tank entry speed until all the objects to be coated are completely submerged in the electrodeposition tank, depending on the number of objects to be completely immersed in the electrodeposition tank. I have done so.

e. Action When the object to be coated conveyed by the main conveyor is put into the electrodeposition tank, it is transferred to the auxiliary conveyor and put into the tank.
Then, the entry speed of the object to be coated is increased from the normal transport speed to prevent the generation of hash marks. After being completely destroyed, it is transferred to the main conveyor again and conveyed.

f. Examples Hereinafter, the present invention will be described in detail with reference to the illustrated examples.

1 and 2 show a coating apparatus used in the electrodeposition coating method of the present invention, in which 1 is an electrodeposition tank containing a paint 2. 3 is a main conveyor that conveys the object to be coated 4,
This is to suspend the article 4 to be coated on a suspending tool 5 provided at a constant interval and convey it at a constant speed by a driving device (not shown).

Reference numeral 6 denotes an auxiliary conveyor which is juxtaposed at the same height as the main conveyor 3 corresponding to the tank section 1 of the object to be coated, and the auxiliary conveyor 6 is driven by a drive device (not shown) so as to be faster than the main conveyor 3. It conveys at high speed. The main conveyor 3 and the auxiliary conveyor 6 are provided side by side at the same height, and the suspenders 5 can be transferred to each other when they are close to each other.

The tank section 1 is an obliquely descending section of the conveyor 6 and is a section from the time the object 4 to be coated comes into contact with the electrodeposition liquid (paint) to the time it is completely submerged in the electrodeposition liquid.

In the section 1 in which the auxiliary conveyors 6 are arranged in parallel, the route of the main conveyor 3 is changed via the sprocket 7, and the hanging tool 5 for the article 4 to be coated in this section 1 is transferred via the auxiliary conveyor 6. I am doing it.

Numerals 8 and 9 are air cylinders for pushing out the suspending tool 5 for the article to be coated 4, and 8 is arranged in front of the auxiliary conveyor 6 to push out the suspending tool 5 for the article to be coated 4 from the main conveyor 3 to the auxiliary conveyor 6. The reference numeral 9 is arranged in front of the entry position and is transferred from the auxiliary conveyor 6 to the main conveyor 3. The auxiliary conveyor 6 can be switched to two speeds and is usually synchronized with the speed of the main conveyor 3. At high speed, the auxiliary conveyor 6 sets the vertical entry speed of the article 4 to be coated to 1 m / min or more, preferably 1.5 m / min or more.

10 is a direct current power supply, which is connected to the electrodeposition tank 1 for positive measurement via a voltage controller 11 and is connected to the bus bar 12 arranged on the negative side above the main conveyor 3 via this. The object to be coated 4 is energized.

Next, a coating method in the case of coating based on the coating device will be described.

The suspending tool 5 for the article 4 to be coated, which has been transported by the main conveyor 3 after finishing the pretreatment, is released from the driving force by the stopper at the set position, becomes a free state, and stops.

On the other hand, the unshown detecting means detects the entering state of the article 4 to be coated in the vessel, and if there is no article 4 to be coated, the auxiliary conveyor 6 is operated at high speed. The entry state is the number of objects 4 to be coated which are totally or almost completely immersed in the electrodeposition vessel, and the limited value of this number is used as a criterion for deciding whether or not to accelerate the auxiliary conveyor 6.

Then, the suspending tool 5 for the article 4 to be coated is transferred from the main conveyor 3 to the auxiliary conveyor 6 via the air cylinder 8 and is conveyed at a high speed by the auxiliary conveyor 6. The auxiliary conveyor 6 conveys the suspending tool 5 for the object to be coated 4 at a higher speed than the main conveyor 3 and allows the object to be coated 4 to enter the tank. At this time, the object to be coated 4
Electric current concentrates on the surface of, but since the bathing speed is fast,
Hash mark does not occur. Then, after the completion of entering the tank, the suspending tool 5 for the article 4 to be coated is again transferred to the main conveyor 3 by the air cylinder 9 and conveyed to be subjected to electrodeposition coating. As a method for increasing the speed of the hanging tool 5 for the article to be coated 4, the upper end of the hanging tool 5 is slidably supported with respect to the main conveyor 3, while the auxiliary conveyor 6 causes the hanging tool 5 to slide.
It is also possible to provide a pressing means such as, for example, an arm so that the arm is engaged with the suspending tool 5 for pressure feeding.

g. Effect of the Invention As described above, according to the electrodeposition coating method of the present invention,
In an electrodeposition coating method, in which an object to be coated hung on a main conveyor via a suspending tool is transported while being immersed in an electrodeposition tank containing a coating material, the object to be coated is an electrodeposition tank. Auxiliary conveyors that can be transported at a higher speed than the main conveyor are installed in parallel with the main conveyor in the section including the area to enter, and the objects to be coated are transferred from the main conveyor to the auxiliary conveyor only when entering the tank. In order to prevent the occurrence of hash marks, the entry speed until the object to be completely immersed in the electrodeposition tank is increased according to the number of objects to be completely immersed in or close to it. it can.

[Brief description of drawings]

1 and 2 show one embodiment of the electrodeposition coating method according to the present invention, FIG. 1 is a conceptual diagram, FIG. 2 is an enlarged plan view of the tank section of FIG. 1, and FIG. FIG. Abc is a conceptual diagram showing a coating mode of the electrodeposition coating method. 1 ... Electrodeposition tank, 2 ... paint, 3 ... main conveyor, 4 ... painted object, 5 ... hanging tool, 6 ... auxiliary conveyor.

Claims (1)

[Claims] 1. An electrodeposition coating method for carrying out electrodeposition coating by immersing an object to be coated hung on a main conveyor through a suspending tool and immersing it in an electrodeposition tank containing a paint. Auxiliary conveyors that can be transported at a higher speed than the main conveyor are installed side by side with the main conveyor in the section including the range where the products enter the electrodeposition tank, and the objects to be coated are transferred from the main conveyor to the auxiliary conveyor only when entering the tank. In addition, according to the number of objects to be completely immersed in or near the electrodeposition tank, the entry speed until the objects to be completely immersed in the electrodeposition tank is increased. How to paint.