JPH0468024B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a device for repairing the inner surface of the side seam of a can body, and more specifically, the present invention relates to a repair device for repairing the inner surface of the side seam of a can body, and more specifically, the present invention relates to a repair device for repairing the inner surface of the side seam portion of a can body, and more particularly, The present invention relates to a device for repairing the inner surface of a seam portion by coating the inner surface with a powder coating.

(Prior Art) U.S. Pat. No. 4,259,923 discloses that a powder paint charged by a corona electrode is applied to the inner surface of the can body near the side seam, that is, by an electrostatic powder coating method. A method for repairing the inner surface is described, but in this case, in order to prevent the powder paint ejected from the ejection port of the horn from adhering to the inner surface of the can body away from the vicinity of the side seam, it is necessary to repair the ejection port. The apparatus is shown with a pair of masking brushes attached to the horn that extend axially along opposite sides of the horn.

However, according to the experience of the present inventors, when such a masking brush is used, a gap (see 19 in Fig. 3) is formed in the longitudinal direction (axial direction), and the powder passing through this gap is Paint tends to adhere to the inner surface of the can body that is farther from the vicinity of the side seam. Heating to melt and weld the applied powder coating to the vicinity of the side seam is carried out only in the vicinity of the side seam, so powder adhering to the inner surface of the can body away from the vicinity of the side seam is The body paint does not weld, and after filling and sealing the contents, it separates from the inner surface and enters the contents, staining the contents. This increases the frequency of replacing the masking brush, which reduces productivity. This results in a problem that the amount of energy decreases.

The reason for the above gap is that powder paint is usually applied while the side seam is still hot immediately after the side seam is formed, but at that time, the powder paint adhering to the lower part of the masking brush coagulates due to the heat. death,
This is believed to be because the aggregated powder paint draws the lower portions of the brush fibers together, creating a dense lower portion of the brush.

It is also possible to use a plate instead of a brush as a masking device, but in this case, a slight gap should be provided between the end surface of the plate and the inner surface of the can body to prevent scratches from occurring on the inner surface of the can body. There is a need. Therefore, the powder coating material that has passed through this gap adheres to the inner surface of the can body away from the vicinity of the side seam, causing a problem in that it is likely to stain the contents in the same manner as described above.

(Problems to be Solved by the Invention) The present invention provides an electrostatic discharge system that prevents powder coating from adhering to the inner surface of the can body away from the vicinity of the side seam even if there is a slight delay in the masking device. The purpose of the present invention is to provide a device for repairing the inner surface of the side seam of a can body using a powder coating method.

(Means for Solving the Problems) The apparatus for repairing the inner surface of the side seam of a can body according to the present invention includes a powder coating spout and a corona for charging the powder coating spouted from the spout. a horn provided with an electrode; a conveyor device for transporting the can body with the inner surface of the side seam portion facing the spout; and a conveyor device installed to extend in the axial direction of the horn along the vicinity of both sides of the spout; It is characterized by comprising a masking device for the powder coating, and an electrode body having a polarity different from that of the corona electrode, which is attached to the horn near the outside of the masking device in parallel with the masking device (hereinafter referred to as (referred to as the first invention).

The apparatus for repairing the inner surface of the side seam of a can body according to the present invention includes a powder coating nozzle, a horn equipped with a corona electrode for charging the powder coating ejected from the nozzle, and a side seam inner surface of the can body. a conveyor device for transporting the can body so as to face the spout; a masking device for the powder coating installed to extend in the axial direction on the horn along both sides of the spout; It is characterized by comprising an electrode body having the same polarity as the corona electrode, which is attached to the horn near the outside of the masking device in parallel with the masking device (hereinafter referred to as the second invention).

Examples of the masking device include a masking brush and a masking plate. Examples of the can body include a pine seam electric resistance welded can body and a butt laser welded can body.

(Operation) In the case of the first invention, in parallel with the masking device,
An electrode body having a different polarity from the corona electrode is provided near the outside of the horn masking device. Therefore, the electrostatic charge of the powder coating and the potential of the electrode body are of opposite polarity (for example, if the former is -, the latter is +),
The powder paint that has passed through the gap between the masking devices is attracted to the electrode body and does not adhere to the inner surface of the can body outside the masking device and away from the vicinity of the side seam.

In the case of the second invention, in parallel with the masking device, an electrode body having a different polarity from the corona electrode is provided near the outside of the masking device of the horn. Therefore, the electrostatic charge of the powder coating and the potential of the electrode body have the same polarity (for example, if the former is -, the latter is also -), so
The powder paint that has passed through the gap in the masking device is immediately repelled by the electrode body and adheres to the inner surface of the can body near the outside of the masking device. Therefore, the powder coating does not adhere to the inner surface of the can body outside the masking device and away from the vicinity of the side seam.

(Example) In Fig. 1, 1 is a can body preform made of tin-plated steel plate, stain-free steel, etc., and while being transferred in the direction of arrow A, its overlapping portions 2 are placed in a pair of opposing positions. A can body 6 having a welded portion 5 is formed by electrical resistance welding of the pine seam by the outer electrode roll 3 and the inner electrode roll 4 via a wire electrode (not shown). An inner surface coating film (not shown) is formed on the inner surface of the can body except in the vicinity of the welded portion 5, and the inner surface near the welded portion forms an exposed metal portion 5a (FIG. 2).

Reference numeral 7 denotes a horn, which includes a conduit 12 for supplying the powder coating 10 from a powder tank (not shown), a powder coating nozzle 8 connected to the conduit 12, a spout 8a at the lower end of the nozzle 8, and a spout 8a. It is provided with a corona pin 9 provided on the upper side, a downstream guide hole 13 and an upstream guide hole 14 for sucking uncoated powder paint and sending it to a powder tank (not shown). The corona pin 9 is connected to a high-voltage DC power source (for example, -20 kV), not shown, via a conductor 15.

11 is a masking brush, which has a spout 8a.
It is attached to the horn 7 via a holder 11b so as to extend in the axial direction of the horn 7 along the vicinity of both sides (FIG. 2). The brush 11 is the brush 11
Even if there is no powder coating 10, the blown out powder coating 10
A location where there is no risk of it flying to the inner surface of the can body that is further away, for example, about 7 cm downstream of the spout 8a.
It extends to about 11cm on the upstream side.

The brush 11 is made of a ceramic fiber having high heat resistance and abrasion resistance, such as a glass fiber, and its tip is bent toward the welding part 5, that is, inward, as shown in FIG. It is in contact with the inner surface. Masking brush 11
An electrode plate 16 having approximately the same length as the brush 11 is attached to the horn 7 in parallel with and near the outside thereof. The electrode plate 16 is connected to a DC high-voltage power source of the same polarity or different polarity as the corona pin 9 (for example, the power source of the corona pin 9 is -20kV) via a conductor (not shown).
When the electrode plates 16 have the same polarity, the power supply voltage of the electrode plates 16 is -5 kV). Electrode plate 16 is covered with an electrical insulator (not shown). Reference numeral 17 denotes a brush that contacts the outer surface (metal is exposed) of the welded portion 5 for grounding the can body 6.

21 is a belt conveyor device for transporting the can body 6, and is driven by a drive roll 22. The can body 6 is arranged so that the inner surface of the welded part 5 faces the spout 8a, that is, passes directly under the latter.
Preferably, the can bodies 6 are transferred so that the distance x between adjacent can bodies 6 is substantially zero (to prevent the powder coating from escaping to the outside of the can bodies as much as possible).

While the can body 6 is being transported, the powder coating 10 is sprayed from the powder coating nozzle 8 onto the exposed metal portion 5a on the inner surface near the welding portion 5 between the pair of brushes 11, resulting in a coating layer 18 (in the circumferential direction). (for example, a width of approximately 10 mm). Next, an outer surface repair paint is applied to the outer surface of the welded part 5 by a coating device (not shown), and the vicinity of the welded part 5 is heated by a heating device (for example, a hot air blowing device) not shown, so that the powder coating of the applied layer 18 is applied. 10 is melted and welded to the exposed metal portion 5a, and the outer surface repair paint is dried.

The fibers 11a forming the brush 11 are originally attached to the horn 7 so as to be substantially parallel to each other, but as the powder coating process progresses, as shown in FIG. The lower end of the fiber 11a is locally close to form a triangular space 19.
is formed. It is presumed that this is because the heat retained in the welding part 5 heats the vicinity of the lower end of the fiber 11a, and the powder coating 10 adhering to the heated vicinity of the lower end aggregates to form the agglomerated part 10a.

When the corona pin 9 and the electrode plate 16 are of the same polarity, the powder coating material 10 that has passed through the gap 19 is immediately repelled by the potential of the electrode plate 16 and is deposited on the can body inner surface 23 near the outside of the brush 11. attached (Figure 2). This deposited powder coating 10 is welded to the inner surface of the can body during the heating described above. On the other hand, in the case of different polarities, the powder coating material 10 passing through the gap 19 is deposited on the electrode plate 16. Therefore, in either case, the time until the brush 11 is replaced can be extended.

FIG. 4 shows a case where a pair of masking plates 24 are used in place of the brush 11, and there is a slight gap 25 between the plates 24 and the inner surface of the can body. In this case as well, if the corona pin 9 and the electrode plate 16 have the same polarity, the powder coating material 10 that has passed through the gap 25 is immediately repelled by the potential of the electrode plate 16, and the powder coating material 10 is immediately repelled by the inner surface of the can body near the outside of the plate 24. It is attached on 23. This deposited powder coating 10 is welded to the inner surface of the can body during the heating described above. On the other hand, in the case of different polarities, the powder coating material 10 passing through the gap 25 is deposited on the electrode plate 16.

(Effects of the Invention) The device for repairing the inner surface of the side seam portion of a can body using the electrostatic powder coating method of the present invention is capable of repairing the inner surface of the side seam portion of a can body even if there is a slight gap in the masking device. This has the effect that there is no risk of adhesion to the inner surface of the trunk.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of a device that is an embodiment of the present invention, Fig. 2 is a vertical sectional view taken along the - line in Fig. 1, and Fig. 3 is an enlarged longitudinal sectional view taken along the - line in Fig. 2. FIG. 4, which is a diagram showing a state after long-time work, is a longitudinal cross-sectional view corresponding to FIG. 2 in a case where the masking device is a masking plate. 5... Welding part (side seam part), 6... Can body,
7...Horn, 8a...Ejection port, 9...Corona pin (corona electrode), 10...Powder coating, 11...
Masking brush, 16... Electrode plate, (electrode body), 18... Paint layer, 21... Belt conveyor device (conveyor device), 24... Masking plate.

Claims (1)

[Claims] 1. A horn equipped with a powder coating nozzle and a corona electrode for charging the powder coating ejected from the nozzle, with the inner surface of the side seam facing the nozzle. a conveyor device for transporting the can body, a masking device for the powder coating installed to extend in the axial direction on the horn along both sides of the spout; A repair device for the inner surface of a side seam portion of a can body, comprising an electrode body having a polarity different from that of the corona electrode, which is attached near the outside of the masking device of the horn. 2. A horn equipped with a powder coating nozzle and a corona electrode for charging the powder coating spouted from the nozzle, and transporting the can body so that the inner surface of the side seam portion faces the nozzle. a conveyor device, a masking device for the powder coating mounted to extend axially on the horn near both sides of the spout, and a masking device for the horn in parallel with the masking device; 1. A repair device for the inner surface of a side seam portion of a can body, comprising an electrode body of the same polarity as the corona electrode, which is attached near the outside.