JPH0532210Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a repair device for the inner surface of the welded part of a can body.
More specifically, the present invention relates to a device for repairing the inner surface of a welded portion of a welded can body used for youth cans, beer cans, etc. by coating the inner surface of the welded portion with a powder coating.

(Prior art) U.S. Patent No. 4,259,923 discloses that a powder paint charged by a corona electrode is applied to the inner surface of a can body near a weld (including a weld), that is, electrostatic powder coating is applied. Depending on the method, means for repairing the inner surface are described, but in this case, in order to prevent the powder paint ejected from the horn nozzle from adhering to the inner surface of the can body away from the vicinity of the welding part. , a device is shown in which a pair of masking brushes are attached to the horn and extend axially along the sides of the spout.

However, according to the experience of the present inventors, when such a masking brush is used, a gap (see 23 in Fig. 3) is generated in the longitudinal direction (axial direction), and this gap is formed along with the carrier gas ejected from the nozzle. Powder paint blown into the can body through the welding part tends to adhere to the inner surface of the can body away from the vicinity of the weld. After application, the powder coating is heated to melt it and weld it to the vicinity of the welding area.Since heating is carried out only in the vicinity of the welding area, the powder coating that adheres to the inner surface of the can body away from the vicinity of the welding area is Without welding, when the contents are filled and sealed, it separates from the inner surface, enters the contents, and contaminates the contents, which increases the frequency of masking brush replacement and reduces productivity. This causes a problem.

The reason why the above-mentioned gap is formed is that powder paint is usually applied while the weld is still hot immediately after the weld is formed, and the powder paint adhering to the masking brush at that time coagulates due to the heat, and the agglomerated powder This is believed to be because the lower portions of the brush fibers are drawn together by the body paint, creating a dense lower portion of the brush.

(Problems to be Solved by the Invention) The present invention provides an apparatus for repairing the inner surface of the welded part of a can body using an electrostatic powder coating method, which reduces the frequency of masking brush replacement and increases productivity. With the goal.

(Means for Solving the Problems) The device for repairing the inner surface of the welded part of the can body of the present invention has a powder coating spout, an upstream inlet that extends along the welded part continuously from the spout, and a downstream inlet. having a mouth
A horn equipped with a suction conduit for uncoated powder paint spouted from the jet nozzle, and a corona electrode for charging the powder paint spouted from the spout, the inner surface of the welded part is the jet nozzle and the upstream side is introduced. A conveyor device that transfers the can body so as to face the mouth and the downstream inlet, and the tip portion contacts the inner surface of the can body near the welding part along both sides of the upstream inlet and the downstream inlet. The present invention is characterized by comprising an inner masking brush and an outer masking brush attached to the horn.

(Function) Powder paint that has spouted out from the spout and has not been electrostatically applied, that is, uncoated powder paint, is passed through a conduit that has an upstream inlet and a downstream inlet that extends along the weld. The powder is sucked out and sent to a powder tank.

Therefore, most of the uncoated powder paint is sucked through the inlet in the direction of the weld, and only a small amount is scattered in the lateral direction of the weld, that is, toward the masking brush.

This extremely small amount of scattered powder paint adheres to the inner masking brush and aggregates, gradually filling the gap 23.
will develop. The powder paint that has passed through this gap 23 hits the outer masking brush, but the amount of powder paint that hits the outer masking brush is small even when the gap 23 between the inner masking brush and the inner masking brush is considerably developed.
It is less than the husband of the inner masking brush. Therefore, the development of the gap 23 on the outer masking brush is much slower than on the inner masking brush. Therefore, the gap 2 between the inner masking brush
3. The working time required for the powder paint to pass through the gap between the outer masking brush and adhere to the inner surface of the can body away from the welded part (for example, the part 18 in Figure 2) and cause actual damage is Compared to the case where the side inlet and the downstream inlet are not provided, and the masking brushes are provided in one row on one side, the length is significantly shortened, and therefore the frequency of masking brush replacement can be reduced.

(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. The corona pin 9 provided at the upper end and uncoated powder coatings 10' and 10'', which are not electrostatically applied, are passed through the downstream inlet 13a and the upstream inlet 14a, respectively, which are continuous with the spout 8a. The corona pin 9 is provided with a downstream guide hole 13 and an upstream guide hole 14 for suctioning and sending the powder to a powder tank (not shown).
A high-voltage DC power supply (not shown) (for example -
20kV).

Reference numeral 16 denotes an inner masking brush, which is held by a holder 16a and extends in the axial direction of the horn 7 along both sides of the downstream introduction port 13a and the upstream introduction port 14a that are continuous with the jet port 8a. , is attached to the horn 7 via a holder 16a (FIG. 2). Even without the inner brush 16 and the outer masking brush 17 (described later), the inner brush 16 can remove the powder paint that is blown and not applied to the inner surface of the can body away from the welding part 5, for example, the part 1.
It extends to a position where there is no risk of it flying up to No. 8 and becoming attached, for example, approximately 7 cm on the downstream side and approximately 11 cm on the upstream side of the jet nozzle 8a.

The inner brush 16 is made of a ceramic fiber 16b having high heat resistance and abrasion resistance, such as glass fiber, and its tip 16c is made of a second ceramic fiber 16b.
As shown in the figure, it is bent toward the welding portion 5 side, that is, inward, and is in contact with the inner surface of the can body near the welding portion 5. Therefore, at the beginning of the painting work, powder paint does not jump out beyond the brushes 16 on both sides. Furthermore, since the brush is relatively flexible, there is no risk of damaging the inner surface of the can body.

Parallel to the inner brush 16 and near its outer side,
An outer masking brush 17 having approximately the same length as the inner brush 16 is attached to the horn 7 via a holder 17a. The outer brush 17 is also the inner brush 16.
Similarly, it is made of a ceramic fiber, for example a glass fiber, and its tip 17c is bent inward and comes into contact with the inner surface of the can body near the welding part 5.

Reference numeral 19 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 such that the distance x between the gaps 30 between adjacent can bodies 6 becomes substantially zero.

By making the interval x substantially 0 in this way, unapplied powder coatings 10' and 10'' are transferred to the spout 8.
In addition to being sucked along the downstream inlet 13a and the upstream inlet 14a that are continuous with a, the uncoated powder paint 10', 10'' is prevented from escaping to the outside of the can body. Therefore, there is no need to provide a hopper to catch the powder paint that has escaped outside the can body.

While the can body 6 is being transferred, a pair of inner brushes 1
In the exposed metal part 5a on the inner surface near the welding part 5 between 6,
A powder coating 10 is sprayed from a powder coating nozzle 8 to form a coating layer 11 (with a circumferential width of about 10 mm, for example). Unpainted powder coating 10',
10'' (see Figure 2) is sucked through the downstream inlet 13a and the upstream inlet 14a, sent to a powder tank (not shown), and collected. Extremely small amount of powder coating 1
0', 10'' adheres to the inner brush 16. Next, after an external surface repair paint is applied to the outer surface of the welded portion 5 by a coating device (not shown), the vicinity of the welded portion 5 is coated by a heating device (not shown, for example, a hot air blowing device). When heated, the powder coating 10 of the coating layer 11 is melted and adhered to the exposed metal portion 5a, and the outer surface repair coating is dried.

Fiber 16b forming inner brush 16
are arranged so that the holding bodies 1 are originally substantially parallel to each other.
However, as the powder coating process progresses, the lower ends of the fibers 16b locally approach each other, forming a triangular gap 23, as shown in FIG. Ru. This is presumed to be because the heat retained in the welding portion 5 heats the lower end portion of the fiber 16b, and the powder paint adhering to the heated lower end portion coagulates to form the agglomerated portion 10a.

The fibers forming the outer brush 17 are also attached to the holder 17a in such a way that they are essentially parallel to each other. At the beginning of the powder coating work, the powder paint does not adhere to the outer brush 17 because it is blocked by the inner brush 16. As time passes during powder coating work, a gap 23 develops in the inner brush 16, and this gap 23
The powder paint that has passed through adheres to the outer brush 17, and eventually a gap (not shown) is formed in the outer brush 17 as well. However, the powder coating passes through both the gap 23 of the inner brush 16 and the gap of the outer brush 17 and adheres to the inner surface of the can body away from the welding part 5, for example, the part 18, until the product loses its commercial value. Painting time is for inner brush 1
If only the spout 6 is installed, and the spout 8a
It is longer than the case where the downstream side introduction port 13a and the upstream side introduction port 14a which are continuous to each other are not provided.
Therefore, the frequency of replacing the brushes 16, 17 is reduced.

A specific example is shown below.

A so-called Sudronik welding device of the type described in Japanese Patent Publication No. 54-26213 was used to
A welded can body (height 182 mm, outer diameter 153 mm) was manufactured at a speed of 10 minutes, and an inner masking brush 16 and an outer masking brush 17 (both of the type shown in FIG. Powder paint (linear polyester, melting point 170°C) was electrostatically applied (corona electrode voltage: -20kV) to the inner surface of the welded part of the welded can body using a repair device equipped with a glass fiber (made of glass fiber). Repairs were made. in this case,
The time it takes for powder paint to adhere to the inner surface of the can body away from the welding area and for the product to lose its commercial value is approximately
It was hot in 24 hours.

For comparison, when the repair was carried out in the same manner as described above except that the outer masking brush 17 was not used, it took about 4 hours until the product lost its commercial value.

Note that the can body may have a welded portion other than the pine seam electric resistance welded portion, such as a butt laser beam welded portion.

(Effects of the invention) The device for repairing the inner surface of the welded part of the can body using the electrostatic powder coating method of the present invention has the effect of reducing the frequency of masking brush replacement and increasing the productivity of repairing the inner surface of the can body in the welded part. play. Furthermore, by transferring the can bodies so that the distance between adjacent can bodies is substantially zero, there is an advantage that there is no need to provide a hopper for receiving uncoated powder paint.

[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. 7 is a drawing showing the state of the inner masking brush after long-time work. 5... Welding part, 6... Can body, 7... Horn, 8
a... Jet nozzle, 9... Corona pin (corona electrode),
10... Powder paint, 10', 10''... Unapplied powder paint, 13, 14... Guide hole, 13a...
...Downstream side inlet, 14a...Upstream side inlet, 16
...Inner masking brush, 16c...Tip,
17... Outer masking brush, 17c... Tip, 21... Belt conveyor (conveyor device).

Claims (1)

[Scope of utility model registration request] a powder coating spout; a suction conduit for powder paint spouted from the spout and not coated; and a horn equipped with a corona electrode for charging the powder paint ejected from the spout, and a conveyor device that transports the can body so that the inner surface of the welded part faces the spout, the upstream inlet, and the downstream inlet. and an inner masking brush and an outer masking brush attached to the horn along both sides of the upstream inlet and the downstream inlet so that their tips contact the inner surface of the can body near the welding part. A repair device for the inner surface of a can body welded part, which is characterized by: