JPH0550357B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention corrects the inner surface of the side seam of a welded can with paint, and uses a relatively thick layer of correction paint to prevent welding steps and metal protrusions due to spatter that occurs during welding. This relates to a correction technique that attempts to prevent corrosion caused by the contents by coating the inside of the container.

(Prior art) Tinplate, TFS material, nickel-plated material, etc. are used as materials for welded cans, but in all materials, there is a step in the welded area, and spatters generated during welding can cause the metal to deteriorate. When applying correction coating to the side seams of welded cans, as protrusions occur.
Must be coated with a relatively thick layer of corrective paint of 20-5μ.

As a method that has been proposed so far,
As disclosed in Publication No. 48-4428, the side seam is heated, the paint powder is electrically charged by corona discharge, and low-pressure air is blown against the inner surface of the side seam of the can body to melt it. There is a method that forms a relatively thick layer of correction paint, and it is actually used overseas, but this method has the disadvantage that the paint powder released toward the side seam will adhere to areas other than the side seam of the can. .

Another method, as disclosed in Japanese Patent Application Laid-open No. 53-144941, is to drive a paint roller dipped in a liquid paint pot and bring the roller into contact with the inner surface of the side seam of the can body. A method is actually used in which the correction paint in the paint pot is transferred onto the side seam, and when using this method, a layer of correction paint with a relatively appropriate thickness can be obtained if the painting speed is slow. When the coating speed is increased to improve productivity, it becomes difficult to coat with a uniform thickness, and a complete correction paint layer cannot be obtained.

Still another method is to spray the paint with an airless spray nozzle as disclosed in JP-A No. 47-3893, but with this method it is difficult to obtain a correction paint layer of about 15μ at most. at most, and complete coverage cannot be expected.

Furthermore, as disclosed in Japanese Patent Application Laid-open No. 58-45773, in the spray pattern of correction paint ejected from an airless spray nozzle, a planar part of the non-atomized area near the nozzle tip is used as a side seam. A method of correcting by applying it has also been proposed,
In this case, the correction paint is applied in a non-atomized state compared to a normal air spray, so even if it is possible to avoid scattering of paint particles, the correction paint is thick enough to the extent described above. It was difficult to obtain layers.

Furthermore, as shown in Japanese Unexamined Patent Publication No. 58-27668, correction is made by causing multiple filamentous paint streams to flow down from an airless spray nozzle along the surfaces on both sides of the level difference in the side seam of the metal can body. A method has also been proposed. However, when using this method, it is difficult to maintain a constant application width of the flowing paint stream, and the flowing paint stream flows beyond the side seam and the area around it that requires correction. Since it is difficult to prevent this, it is difficult to obtain a uniform thick layer of correction paint only on the side seam of the welded can and the area around it that requires correction.

(Problems to be Solved by the Invention) As described above, with the conventional technology, only the side seams of welded cans and the areas around them that require correction are coated with a uniform and relatively thick layer of correction paint. There is a need for a means to obtain a thick and uniform correction paint layer even when the coating speed is not perfect and the coating speed is increased.

(Means for Solving the Problems) The present invention aims to eliminate the drawbacks of the conventional correction coating method as described above. A freely rotatable rotor is provided so as to straddle and contact the side seam, and while rolling the rotor, the correction paint is pushed out in a column shape from the extrusion nozzle, thereby correcting the side seam and its surroundings. The aim is to cover only the necessary areas with a relatively thick layer of correction paint.

(Example) To explain the present invention with reference to an example, first, as shown in FIG. Then, the correction paint is extruded in a column shape from an extrusion nozzle 3 provided at the tip of a pipe 2 for feeding the correction paint, and the welded can side seam 5 and its surrounding area are covered with a thick layer of correction paint. Can body 4 indicates a can body that has completed the correction process and is moved to the next baking process.

As is clear from FIG. 2, the extrusion nozzle 3 is located close to the side seam 5 of the welded can. A rotor 6 rotatably attached to both sides of the extrusion nozzle 3 is provided so as to straddle the side seam 5 and contact the can body, and maintains the extrusion nozzle 3 at a constant position with respect to the side seam 5. At the same time, it serves to prevent the correction paint extruded in a column from flowing in the circumferential direction of the can body beyond the side seam 5 (usually about 7 mm wide) and the area around it that requires correction.

FIG. 3 shows a first embodiment of the extrusion nozzle of the present invention, in which a plurality of small-diameter orifices 7 are arranged, and correction paint is distributed and distributed to each orifice 7 through a feed hole 8. The correction paint is applied directly onto the welded can side seam 5 and its surrounding area in the form of a plurality of thin columns. Since the can body passes one after another in contact with the rotor of the extrusion nozzle, the correction paint can be applied in the form of a band of a constant width only to the side seam and the area around it that requires correction.

Generally, there is a gap between the can body and the can body, but if a sensor is used to detect the passage of the can body, and a solenoid valve is used to push out the paint only when the can body is passing, it is possible to Prevents stains caused by dripping.

FIG. 4 shows a second embodiment of the extrusion nozzle of the present invention, in which the correction paint fed through the feed hole 8 becomes thinner than the slit 10 of the extrusion nozzle 3 and forms a thin plate at the side seam of the welded can. 5 and its surrounding areas. Although the rotor 9 in this example is smaller compared to the example of FIG. 3, its action is similar to that of the rotor 6.

Figure 5 shows a case where the side seam of a welded can faces upward, and the correction paint is extruded in a column shape from the upward side seam by an extrusion nozzle having a group of small-diameter orifices. This shows the coating state when the extruded correction paint is applied to the upward side seam.

Figure 7 shows the situation when the side seam of the welded can is facing downward and the correction paint is pushed out downward with an extrusion nozzle having a slit, and Figure 8 shows the situation when the correction paint is applied to the side seam facing downward. Shows the condition of the coating.

The extrusion nozzle described above can be suitably used for any paint such as epoxy resin paint, phenol resin paint, vinyl resin paint, vinyl organosol paint, etc. by appropriately selecting the paint viscosity and extrusion pressure. .

(Effects of the Invention) According to the present invention, the liquid correction paint is applied directly to the side seam by extruding it, and
Since the coating width is kept constant at the width between the rotors on both sides,
The correction paint layer can be made thick and uniform enough to completely cover not only the steps in the welding area but also the metal protrusions caused by spatter during welding.
In addition, since the correction paint layer can be applied only to the side seam and the areas around it that require correction, the correction coating is suitable for filling the welded can with highly corrosive contents. be able to.

The liquid correction paint is applied by flowing down from the extrusion nozzle while rolling the rotor that straddles the side seam and contacts the can body, so the extrusion nozzle can be kept in a fixed position relative to the side seam. Can be painted stably.

Since the application width of the correction paint can be kept constant to the width between the rotors on both sides of the extrusion nozzle, a correction paint with good appearance can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an overall view showing the present invention, FIG. 2 is a sectional view showing the first embodiment of the invention, FIG. 3 is an overall view of the extrusion nozzle in the first embodiment, and FIG. 4 is a second embodiment.
An overall view of the extrusion nozzle in the embodiment, FIGS. 5 and 6 are schematic diagrams explaining the correction coating according to the first embodiment, and FIGS. 7 and 8 are schematic diagrams explaining the correction coating according to the second embodiment. It is. 3... Extrusion nozzle, 5... Welding can side seam, 6, 9... Rotor, 7... Orifice, 1
0...Slit.

Claims (1)

[Claims] 1. A rotor rotatably attached to both sides of an extrusion nozzle placed close to the side seam of a welded can is provided so as to straddle and contact the side seam, and extrude the extrusion while rolling the rotor. A method for correcting the inner surface of a side seam of a welded can, characterized in that the area including the side seam is coated with a relatively thick layer of correction paint by extruding the correction paint in a columnar shape from a nozzle. 2. The method of correcting the inner surface of a side seam of a welded can according to claim 1, characterized in that a plurality of small-diameter orifice groups are arranged in the extrusion nozzle to extrude the correction paint in the form of a plurality of columns. 3. The method of correcting the inner surface of a side seam of a welded can as claimed in claim 1, characterized in that the extrusion nozzle is provided with a narrow slit to extrude the correction paint.