JPS6144547B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating method, and more particularly to a coating device for coating a welded portion on the outer surface of a welded can body and exposed metal portions in the vicinity thereof.

Conventionally, welded can bodies used in the production of carbonated beverage cans, youth cans, powdered milk cans, and other miscellaneous cans are coated with anti-corrosion coating on the inside surface of the can body, leaving the area near the welds. It is formed by rolling up a metal blank with a printed coating etc. on the surface that should become the outer surface to form an overlapping part, and then electrical resistance welding (mainly pine seam welding) this overlapping part. There is. Metal blanks are mainly made of steel such as tin-plated steel plate or stain-free steel, but in this case, the welded parts and the exposed metal parts on the outside of the can body near the welds will rust over time. Since this occurs easily, it is desirable to repair it by applying paint.

As a preferable coating method, Japanese Patent Publication No. 58-6542 discloses that the method has a circumferential surface with a width approximately equal to the width of the exposed metal part, and a concave groove that is deeper than the height of the step of the welded part along this circumferential surface. A method of applying the paint using a coating roll has been proposed. As a method for supplying paint to this application roll, a method has been disclosed in which the paint in the paint tank is pulled up by a pull-up roll, transferred to an intermediate roll, and then transferred from the intermediate roll to the application roll.

However, it has been found that the conventional method using three rolls as disclosed in this disclosure has the following problems.

(b) It is preferable from the viewpoint of productivity to apply the paint immediately after exiting the welding equipment, that is, to perform it in-line, but in this case, the space required for the painting equipment increases and the work efficiency of other equipment is affected. This has the disadvantage of impairing the

(b) The coating amount is controlled by adjusting the gap between the pulling roll and the intermediate roll, and the gap between the intermediate roll and the coating roll, so it is difficult to control and it is difficult to obtain the desired coating amount. .

(c) Even if the transfer of the can body is temporarily stopped (for example, for several minutes) due to a problem with the welding equipment, paint will continue to be supplied to the applicator roll for a while, so
Paint builds up on the applicator roll. As a result, the first few can bodies after the transfer is resumed are coated with a large amount of paint, causing defects such as insufficient drying, foaming, and uneven coating, and these defective can bodies must be discarded.

It is an object of the present invention to solve the problems of the prior art described above.

In order to achieve the above object, the present invention provides a welded portion and an exposed metal portion in the vicinity of the outer surface of a welded can body that is transported in the axial direction, having a circumferential surface with a width approximately equal to the width of the exposed metal portion. In a coating method in which a coating material is applied at a coating station using a coating roll having a circumferential groove formed on the circumferential surface, the coating material is directly supplied to the circumferential surface from a coating nozzle at a coating supply station, The paint that has flowed out from the peripheral surface of the coating roll is removed by a side scraper between the supply station and the coating station. The present invention provides a method for painting an exposed metal portion of a welded can body, characterized in that paint remaining on the circumferential surface is removed by a circumferential scraper.

The present invention will be described below with reference to the drawings.

In Figures 1 and 2, 1 is a welded can body, which is usually made by rolling a blank of a thin metal plate based on steel such as tin-plated steel plate or stain-free steel to form side overlapped parts. The welded portion 2 is formed by electric resistance pine seam welding of this overlapping portion using a pair of welding rolls (not shown) disposed on the left side of FIG. As shown in Fig. 2, the welded part 2 and the outer surface (the inner surface is the same) in the vicinity thereof are as follows:
This is an exposed metal portion 3, and a coating film 4 such as a printed coating film is formed on the outer surface of both sides of the exposed metal portion 3.

While the welded can body 1 is being transported along the mandrel 5 in the direction of the arrow X, that is, in the axial direction, by a feeding mechanism (not shown),
At , a paint 7 (for example, an epoxy-based clear paint or a pigment-containing paint) is applied to the exposed metal portion 3 on the outer surface side by a coating roll 6 rotating in the direction of arrow M at the same circumferential speed as the speed of the welded can body 1. be done.

The applicator roll 6 is usually made of metal such as stainless steel, and has a circumferential groove 6b formed in a circumferential surface 6a having a width approximately equal to the width of the exposed metal portion 3. The depth of the circumferential groove 6b is determined to be greater than the height of the stepped portion 2a of the welded portion 2, and during coating, the portion of the circumferential surface 6a within the circumferential groove 6b and the upper corner of the stepped portion are coated. 2a ₁ is designed not to touch.

Reference numeral 8 denotes a needle-shaped application nozzle, which is connected to a sealed paint tank 11 via an air valve 9 and a paint pipe 10. It is connected to a pressurized air source (not shown) via a paint tank 11, an air pipe 12, and a regulator 13. Then, when the pressurized air 14 is fed into the paint tank 11, the paint 7 is pressurized and flows out from the coating nozzle 8 in a linear manner, so that the paint 7 flows in a circumferential direction at the supply station B near the top of the coating roll 6. It is designed to be supplied to the groove 6b.

The supply of paint 7 and its stopping are performed by opening and closing an air valve 9. Further, the supply amount of the paint 7 is controlled mainly by adjusting the air pressure by the regulator 13 and by setting the inner diameter of the coating nozzle 8, so that stability is ensured. The above supply amount is
Normally, so that the circumferential groove 6b is filled with the coating material 7, some coating material 7 is deposited on the side surface 6c of the applicator roll 6 beyond the outer protruding circumferential surface portions 6a' on both sides of the circumferential groove 6b. It is determined by the extent to which it overflows.

In order to remove this overflowing paint 7 from the side surface 6c before reaching the coating station A, gutter-shaped inclined side scrapers 15 are provided on both sides of the coating roll 6 in contact with the side surface 6c. A paint receptacle 16 is provided below the lower end portion 15a of the side scraper 15, and the paint 7 that has entered the side scraper 15 flows down into the paint receptacle 16 and is stored therein. By scraping the paint spilled onto the side surface 6c as described above, it is possible to form a paint film 18 that extends linearly along the outer surface of the exposed metal portion with a sharp side end.

The welded can body 1 has a gap 1 as shown in FIG.
7 (the interval l is usually 1 to 30 mm) and are transferred one after another. Therefore, the amount of paint remaining on the circumferential surface 6a of the applicator roll 6 after passing through the applicator station A is divided into the amount of paint remaining on the circumferential surface 6a of the applicator roll 6. In comparison with part N, the latter is far more variable. With this variation as it is, at the paint supply station B, the peripheral surface 6
When a certain amount of paint is supplied to a, the amount of paint applied to the exposed metal portion 3 that is in contact with the peripheral surface N of the subsequent welded can body 1 will be greater than that of the exposed metal portion 3 relative to the peripheral surface M. has become much more numerous,
This results in uneven coating amount along the longitudinal direction of the exposed metal portion 3. This is undesirable because it causes insufficient drying and impairs the appearance of the product.

In order to prevent the above defects from occurring, the lower surface 19a
A peripheral surface scraper 19 having a shape corresponding to the peripheral surface 6a of the coating roll 6 and having a lower surface 19a in contact with the peripheral surface 6a is provided between the outlet side of the coating station A and the paint supply station B. . By this peripheral surface scraper 19, the paint remaining on the peripheral surface 6a is almost completely removed by the time it reaches the paint supply station B. The removed paint passes along the side surface 6c of the applicator roll, enters the side scraper 15, and is stored in the paint receiver 16.

Note that the paint supply station B has a coating roll 6.
a position B' corresponding to the intersection line of the surface parallel to the axis of the welded can body 1 passing through the center O of the coating roll and the circumferential surface of the applicator roll;
Located above position B', the central angle θ with position B' is approximately
Preferably, it is provided in the middle of position B'' which is 120 degrees.

With the above device, the exposed metal part 3 of the welded can body 1 is
The painting of the outside surface is done as follows.

Immediately after welding, the welded can body 1 is preferably blown onto the welded part 2 with an inert gas, so that the welded part 2 is placed upward and around the applicator roll 6 while the exposed metal part 3 retains its metallic luster. They are transported along the mandrel 5 in the direction of the arrow X at a predetermined distance 1 so that the center line of the surface 6a and the center line of the exposed metal portion 3 are aligned.

Immediately before the first welding can body 1 reaches the coating station A, the air valve 9 opens and the coating nozzle 8
A fixed amount of paint 7 per unit time is supplied to the circumferential groove 6b of the applicator roll, and the paint on the circumferential surface 6a is applied to the exposed metal portion 3.

Since the width of the circumferential surface 6a and the width of the exposed metal portion 3 are approximately equal, the circumferential surface portion 6 protruding outside the circumferential groove 6b
The part of the metal exposed part 3 facing a' is also the circumferential part 6
The paint originally attached to a' and the surrounding surface part 6
In the narrow gap between a' and the exposed metal part 3,
During application, the paint is applied by entering from the circumferential groove 6b. At this time, the paint spreads over a small width outward of the peripheral surface portion 6a', so that the coating is applied even along the edge of the coating film 4, albeit in a very narrow width, and the exposed metal portion 3 is completely covered. covered with paint.

For example, due to problems with welding equipment, etc.
When the transfer of the welded can body 1 stops, the air nozzle 9 is immediately closed and the supply of paint to the applicator roll 6 is stopped.
It is possible to prevent paint from building up on a.

The paint film 18 formed as described above is dried by a drying device provided downstream, for example, a hot air nozzle (not shown), and becomes a dry paint film.

The present invention is not limited to the above examples; for example, the paint may be supplied to the coating roll by a nozzle such as a spray nozzle, a falling nozzle, or a dripping nozzle. Further, the nozzle may be opened and closed using an electromagnetic valve or the like. Alternatively, the welded can body may be moved so that the welded portion is downward, and the coating may be performed by disposing the coating roll below the mandrel.

Further, a scraper having a straight end opposite to the side scraper is provided opposite to the portion of the coating roll shown in the circumferential view, and the amount of paint on the outer circumferential surface portion 6a' after leaving the scraper is adjusted to a desired amount. It may be adjusted to a fixed amount.

According to the present invention, since the coating nozzle supplies the coating material to the coating roll, the space occupied by the coating device is reduced, the amount of coating can be easily adjusted, and the transfer of the welded can body is stopped. By closing the coating nozzle when the paint is dripping, it is possible to easily prevent the paint from building up on the coating roll.

Furthermore, since the side scraper removes the paint that has flowed to the side of the coating roll before application, the side edges of the paint film are not disturbed in a wavy manner, but are sharpened in a straight line, and the formed paint film is It has the advantage of good appearance. Further, since the paint remaining on the circumferential surface of the coating roll after coating is removed by the circumferential scraper, it has the advantage that a coating film of uniform thickness can be formed along the length of the exposed metal portion.

[Brief explanation of the drawing]

FIG. 1 is a front view of an example of an apparatus used for carrying out the present invention, and FIG. 2 is a partially cutaway side view taken along the - line in FIG. 1. DESCRIPTION OF SYMBOLS 1... Welded can body, 2... Welded part, 3... Metal exposed part, 6... Application roll, 6a... Surrounding surface, 6b
... Circumferential groove, 6c... Side surface, 8... Painting nozzle, 15... Side scraper, 19... Circumferential scraper, A... Application station, B... Paint supply station.

Claims (1)

[Claims] 1. The outer surface of the welded can body that is transferred in the axial direction,
Paint is applied to the welded part and the exposed metal part in the vicinity at a coating station by a coating roll having a circumferential surface with a width approximately equal to the width of the exposed metal part and having a circumferential groove formed on the circumferential surface. In the coating method, the paint is directly supplied to the peripheral surface from a coating nozzle at a paint supply station, and the paint flows out from the peripheral surface onto the side of the coating roll during the time from the supply station to the application station. The welded can body is characterized in that the paint remaining on the peripheral surface is removed by a peripheral scraper between the application station and the paint supply station. How to paint exposed metal parts.