JPS601909Y2 - Side weld joint forming device for welded can bodies - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for forming a side weld seam suitable for correcting the weld seam by coating the side weld seam of a welded can body with a resin powder coating.

Until now, welded parts have been partially used in the field of cans for dried fruits such as nuts or near-sol cans, but if the welded part is completely coated, it can also be used for general food and beverage cans, making it a can with a wide range of applications. It is the body.

However, in order to completely cover this welded part, there are the following problems.

In other words, a thick oxide film is formed on the weld metal due to the high temperature of the metal material at the welding part, and when coating this oxide film with paint, the oxide film layer is generally brittle, so it may be damaged by shock or vibration. The coated paint may peel off along with the oxide film, exposing the metal and corroding it, causing perforations or leaching the metal into the contents, resulting in hygiene problems.

Furthermore, the oxide film is destroyed in areas where large external forces are applied due to flanging and double seaming of the can body, making the above-mentioned problems more pronounced.

It goes without saying that this oxide film layer is undesirable because it generally appears black in appearance.

The present invention was completed as a result of various researches in order to eliminate such conventional drawbacks, focusing in particular on the characteristics of the oxide film formed at the welded seam of the welded can body made of tinplate material.
The present invention provides a device that is suitable for correcting the welded seam by coating it with resin powder paint and forms a beautiful welded seam, and forms a can body by polymerizing the side edges of tinplate material 1. A shell forming device 2, a welding device 3 for welding the overlapping side edges to form a welded seam, and an oxide film removing device 4 for removing an oxide film formed on the welded joint provided near the welding completion position of the welded seam. Tokara.

An example of implementing the present invention will be described below with reference to the drawings.

A can body material formed from a tinplate material 1 is overlapped at both side edges by a can body forming device 2 constituted by a Z-shaped guide rail to form a can body.

The overlapping side edge is then transferred to a welding device 3 consisting of a pair of upper and lower welding rolls 5, 5 and copper wire electrodes 6, 6 attached to the welding rolls 5, 5. By applying an alternating current welding current to 6, the parts 6 are compressed and heat-generated welded to form a welded joint.

At this time, a black tin oxide film is formed on the welded joint, but it is removed by an oxide film removing device 4 provided near the welding rolls 5, 5.

As shown in the second figure, the oxide film removing device 4 includes a pair of upper and lower heat-resistant brushes 7.7 that come into contact with each other in a direction reverse to the traveling direction of the welded joint that is being welded and transported, and removes oxidation that adheres to the brushes 7.7. It is composed of souffle bars 8, 8 for removing the film and oxide film receiving trays 9, 9 provided below the souffle bars 8, 8.

Therefore, to explain in detail the removal of the oxide film at the weld joint, tin on the surface of the tin plate 1 forming the can body becomes molten immediately after welding, and tin oxide with a melting point of 1327°C forms a film. The metal tin inside is in a molten state because its melting point is as low as 220°C, and in this state, the heat-resistant brush 7
．． 7, the tin oxide film can be easily peeled off mechanically along with the molten metal tin.

The can body from which the oxide film has been removed is then transported to a coating position while being grounded by a presser rod 10, as shown in the first figure, and at this position, the welded joint is ejected from an ejection hole 12 charged by a high voltage application electrode 11. The resin powder coating is electrostatically applied as a coating and then heated from the outside by a heating burner 13 to bake and harden the powder coating.

During the coating process, once the oxide film has been removed, the temperature of the welded joint will drop rapidly, and no harmful oxide film will be formed again.

In the illustrated embodiment, the oxide film removing device 4 is composed of a heat-resistant brush 7.7, but the material is soft and heat-resistant, such as a reversing felt roller, a fixed brush, or a rag. The purpose of the present invention will not be hindered even if a device composed of certain materials is used.

A can body with resin powder coating on a welded can body with a side weld seam from which the oxide film was removed using the device of the present invention (implemented product) and a can body constructed in the same manner without removing the oxide film (comparative example). The results of the quality test are as follows.

■ Composition of the can body used for quality tests 1) Can body material Tinplate material 2) Can body paint Epoxy phenol paint 3) Weld seam correction paint Epoxy paint 4) Correction painting method
Powder electrostatic coating 5) Can bottom lid
Tinplate material 6) Can bottom lid paint Epoxy/phenol paint (7) Can top lid Aluminum (8
) Can canopy paint Double coat of epoxy/phenol paint and thermosetting vinyl paint■ Iron elution amount comparison test Filling: Cola beverage Storage period: 6 months Test can number: 2 nights each Test can body: 202D, 250 cells Storage condition: ERV value comparison test Test can body: 202D Measurement method: With the can can top down, fill with 30% saline, insert a stainless steel electrode, and set the can body to positive. Measurement of current value (mA) at a voltage of 2V Thus, according to the present invention, since the device 4 for removing the oxide film formed on the surface of the welded joint is provided near the welding completion position of the welded joint, it is possible to remove the oxide film from the tinplate material. The tin oxide film can be easily removed together with the metal tin while the metal tin under the tin oxide film on the surface of the welded joint of the can body is in a molten state.
Therefore, when a correction coating is applied on the weld seam, the correction coating film will not peel off or crack during flange processing or double seam processing, making it suitable for food cans, beverage cans, etc. Since there is no oxide film on the joint, the shiny surface of the iron of the tin plate material appears, and it is effective in providing a device with a simple structure that can form a beautiful side weld joint.

[Brief explanation of the drawing]

What is shown is an example of the implementation of the present invention.
The figure is a diagram to explain the entire process, and Figure 2 is the same as Figure 1.
-■ Line cross-sectional view. 1... Tinplate material, 2... Can body forming device, 3... Welding device, 4... Oxide film removal device.

Claims (1)

[Scope of utility model registration request] A can body forming device 2 that overlaps the side edges of the tin plate material 1 to form a can body shape, a welding device 3 that welds the overlapping side edges to form a welded seam, and a welding device 3 located near the welding completion position of the welded seam. A side weld seam forming device for a welded can body, comprising an oxide film removing device 4 for removing an oxide film formed on the surface of the weld seam provided.