JPS63264169A - Method for coating metallic band in continuous coating line - Google Patents

Abstract

PURPOSE:To improve yield for material by performing welding by means of butt welding or lap welding in a slightly overlapped state and pasting a tape stuck with an adhesive on whole parts of the welded part and continuously coating the welded part pasted with the tape with a roll coater. CONSTITUTION:After welding both the rear end of the preceding metallic band 1 and the tip of the following metallic band 2 with resistance welders 3, 3a, pretreatment is preformed with a pretreatment equipment and the welded part is continuously coated with a roll coater. In the case of coating the metallic bands in the continuous coating line, the above-mentioned welding is performed by means of butt welding or lap welding in a slightly overlapped state and a tape 5 stuck with an adhesive is pasted on whole part 4 of the welded part and also the welded part pasted with this tape is continuously coated with the roll coater. In other words, the welded part is continuously coated without damaging the applicator roll of the roll coater and the front and rear parts of the welded part can be coated in the aimed coating specification. Therefore only the welded part pasted with the tape is made to scrap and yield for material can be remarkably improved in comparison with a conventional method which is compelled to speed-down of continuous coating machine train or taking-off of coating applicator at the coating of welded parts.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention is a method of welding metal strips in sequence using a roll coater.
The present invention relates to a method for coating metal strips on a continuous coating line, which improves the relative yield.

(Prior Art) Conventionally, coating of metal strips such as steel strips has been generally carried out on a continuous coating line using the a-le coat method.

The painting process in this painting line usually involves welding the rear end of the leading metal band and the leading end of the trailing metal band using a resistance welding machine, and then
Perform pre-treatment with a pre-treatment device and paint with a roll twoter.
This is followed by a step of drying using a baking dryer.

When painting metal strips on this painting line, the two-coat, two-bake method that coats the metal strip with an undercoat and a topcoat is common, so the roll coater and baking dryer are each Install two units and place them alternately,
First, an undercoat is applied with a roll coater, then baked and dried, and then a top coat is applied with a human roll coater and then baked and dried.

In addition, roll coaters use a rubber applicator roll that applies paint to the metal strip, and can be applied to the metal strip during painting so that it can be used to start and stop painting, change colors, stop the line, etc. It has a structure that ends with advance and retreat. Therefore, the applicator roll is moved gently toward and away from the metal band. This is because in AM, the paint pan containing the paint moves along with the applicator roll, so the paint flows out from the paint pan, and since the applicator roll is made of rubber, it suddenly hits the metal band. This is because if the roll comes into contact with the roll, the drive source motor may be overloaded or the roll may become partially worn out, making it unusable.

By the way, when welding metal strips on this painting line, the metal strips are welded with a resistance welder butt against each other or slightly overlapping each other, but when welding with the former method, there may be a step or weld at the overlapped part of the metal strips. Even if the latter is used for welding, bead-like protrusions will occur on the melt #kS, and if it is coated with a cool coater, it will damage the applicator roll. For this reason, when the weld area is too close during painting, the applicator roll is moved backward, and after passing the weld area, it is moved forward again to paint.

The applicator roll must be moved forward and backward when applying the undercoat, topcoat, and backside coating, but when applying the undercoat and backside coating, it should be done based on the welding area standards, and when applying the topcoat, it should be applied to the base coat of the preceding metal strip. This is done based on the area where painting has finished and the area where undercoating of the trailing metal band has started. When applying the topcoat, use the end and start portions of the undercoat as a reference. If you use the fB contact area as a reference, you will end up painting to areas where there is no undercoat, and after painting, there will be no undercoat. Since the presence or absence of paint cannot be determined, defective products with only top coats may be mixed in.

(Problem to be solved by the invention) Therefore, before and after the weld, there are unpainted areas or areas where only the undercoat is applied. (Around 10-) This occurred.

However, since this part cannot be used as a product, it is scrapped, but there is a FIRM in which the yield of the sealing material decreases when scrapped. In particular, as coating speeds have increased in recent years, the applicator roll must be advanced and retracted quickly with safety in mind, which has led to an increase in the amount of parts to be scrapped, leading to a significant decline in sealant yield.

For this reason, it was necessary to take measures to improve the yield of sealing material.

(Means for Solving the Problem) The present invention, when painting a metal strip, performs welding by butt welding or overlap welding in a slightly overlapping state,
The sealing material yield was improved by applying adhesive tape to the entire weld area and continuously coating the area to which the tape was applied using a roll coater.

Here, the tape attached to the welding part is heated in a baking furnace, so the temperature at which the metal strip is heated in the furnace (plate ff1
) Use a material that does not melt entirely at around 250°C (around 350°C at ambient temperature) 0 For example, use metal tape or foil made of aluminum or stainless steel, resin tape or cloth tape made of polyimide resin, etc. do it.

It is preferable to use a thickness of 30 to 200 μm.

If you want to paint both sides of the metal strip, apply tape to both sides.

The attached drawings show one example of the method for applying tape to the welding part. Figure 1 shows the state in which the leading metal strip and the trailing metal belt are welded by resistance welding, and Figure 2 shows the state in which the leading metal band and the trailing metal band are welded by resistance welding. , FIG. 3 shows the state after welding is completed, FIG. 3 shows the state in which the tape is pasted to the welded part, and FIG. 4 shows the state after the tape pasting is completed. In the figure, 1 is a leading metal band, 2 is a trailing metal band, and 3.
3a is an electrode, 4 is a welding bead, and 5 is a tape.

(Function) As described above, when the tape is applied to the welded part, the metal plate steps and bead-shaped protrusions at the welded part are covered and become smooth. Therefore, even if you apply with an applicator roll, a
- The welds can be painted continuously, as the tubes are not damaged. In addition, even if the tape softens or partially melts in the baking oven, it is cooled by the cooling device installed on the exit side of the baking oven, so even if it comes into contact with the deflector roll or support roll after baking, the tape or #i No adhesive adheres)
.

After painting, there are no unpainted parts or areas that are only coated with the undercoat before and after the weld, so you only need to cut and remove the weld. It can be identified by the tape when it comes close to the surface.

(Example) Example 1 A continuous coating line with one type of 01 coater, plate thickness 0.27
-11. The rear end of the preceding steel strip with a plate width of 914-1 and a plate thickness of 0.35
mm, the tip of the trailing hot-dip galvanized steel strip of plate @914a+m is butt welded with the resistance groove **, 200 μ thick adhesive-coated aluminum foil is pasted on both sides of the weld, phosphate treated, undercoated, The hot-dip galvanized steel strip was painted through the processes of baking drying, top coating and back coating, and baking drying. For the undercoat, epoxy paint was applied using the natural rotation method to a dry film thickness of 5μ, and for the top coat and back coating, polyester paint was applied using the reverse rotation method to a dry film thickness of 15μ. The former was baked at a board temperature of 200°C, and the latter was baked at a board temperature of 230°C. During undercoating, topcoating, and backside coating, even if the welded area was rough, the applicator roll was continuously coated without separating it from the steel strip, but the applicator roll was not damaged. Furthermore, when the aluminum foil was observed at the cutting machine on the exit side of the line, no deformation was observed.

Example 2 In the same manner as Example 1, the plate thickness was 1. Osm, board width 12191! 1.1.2-Zeng, a hot-dip galvanized steel strip with a width of 1219 mm was continuously coated. A stainless steel foil with a thickness of 30 μm was used as the tape to be attached to the welded portion, and an alkaline pretreatment was performed on the tape. In addition, the undercoat is a polyester paint with a dry film thickness of 5μ, and the temperature is 215℃ (board temperature).
For the top coat, a fluorine-based paint was applied to a dry film thickness of 13 μm and baked at 250°C. As a result, the applicator roll was not damaged and the stainless steel foil remained attached.

(Effects of the Invention) As described above, the present invention allows continuous coating of the welded part of the metal strip without damaging the applicator roll of the roll coater, so it is possible to paint the front and back of the welded part to the desired coating specifications. can. Therefore, only the tape-applied portion of the welded portion is scrapped, and the sealing material yield can be improved more significantly than in the conventional painting method. In addition, since the tape covers the deposited metal scum generated at the welded part due to welding, the welded metal scum adheres to the rolls in the painting line and causes scratches, abrasions, and other damage to the coating metal strip and coating. can be prevented.

[Brief explanation of drawings]

Figure 1 shows the leading metal band and trailing metal band JIjG by resistance welding.
Fig. 2 is a perspective view after welding is completed, Fig. #43 is a perspective view of tape being applied to the welded part, and Fig. 4 is a perspective view of the welded area being welded. It is a perspective view after completion.

Claims (1)

[Claims] When painting the metal strip in a continuous coating line where the rear end of the leading metal strip and the tip of the trailing metal strip are welded using a resistance welding machine, pre-treatment is performed using a pre-treatment device, and coating is performed using a roll coater. A continuous coating line in which welding is performed by butt welding or slightly overlapping overlap welding, adhesive tape is applied to the entire welded area, and the welded area to which the tape is applied is also continuously coated with a roll coater. How to paint metal strips.