Metal sanitary can and outer complementary coating device and method for weld joint blank area of metal sanitary can

Abstract

The invention discloses a metal sanitary can which comprises a can body, wherein a weld joint is formed in the can body; weld joint blank areas are formed in two sides of the weld joint; the weld joint blank areas coated by UV photocuring coating layers. The invention further discloses an outer complementary coating device the for weld joint blank areas of the metal sanitary can. The outer complementary coating device comprises a bracket, wherein a can body conveyer belt is arranged above the bracket; an outer weld joint coating device and a photocuring device for coating a UV photocurin coating on the can body are sequentially arranged above the can body conveyer belt; the photocuring device comprises a shell; a UV lamp is arranged inside the shell; a UV lamp reflecting cover is arranged on the outer side of the UV lamp; a ventilation mechanism is further arranged inside the shell; an inlet and an outlet of the can body are formed in two sides of the shell. The invention further provides an outer complementary coating method of the weld joint blank area of the metal sanitary can. The weld joint blank area caused by a conventional outer complementary coating process is eliminated, the production efficiency is greatly improved, the problem of atmospheric pollution and operator body health damage caused by the conventional outer complementary coating process can be solved, and the UV photocuring material has little discharge or volatilization in curing.

Description

technical field [0001] The invention relates to the field of metal packaging, in particular to a new type of external repair coating device and method for a metal three-piece can and its welding seam blank area. Background technique [0002] In the field of metal packaging at home and abroad, the basic process of almost all metal welding three-piece cans is: cutting - welding round can body - inner weld repair (powder or liquid repair, some Japanese products are film coating) - Traditional paint recoating (spray or roll coating) on ​​outer welds—heat drying and curing in a U-shaped drying furnace (used to heat cure powder and liquid paints)—transmission—necking, flanging—subsequent processing, etc. Among them, the external weld repairing process is to use traditional paint (basically all acrylic type, with a solid content of about 30%) for repairing. Using this repairing method (using spray or roller coating device) for construction, if the coating film is thin, it cannot C...

AI Technical Summary

Problems solved by technology

Among them, the external weld repairing process is to use traditional paint (basically all acrylic type, with a solid content of about 30%) for repairing. Using this repairing method (using spray or roller coating device) for construction, if the coating film is thin, it cannot Completely cover the gap area of ​​the weld seam; if the coating film is thicker, due to the high temperature (about 40-60 degrees Celsius) in the gap area of ​​the weld seam of the tank body, the subsequent U-shaped drying furnace uses heat-cured coating, During the heat-curing coating process, there will be dense bubbles in the blank area of ​​the weld (a large amount of solvent overflows when heated), and there will be holes in the coating film and appearance defects; therefore, it is difficult to adjust the thickness of the coating film

[0003] Therefore, the above-mentioned traditional paint coating method for external touch-up coating seriously restricts production efficiency and product quality. At the same time, this coating method also has the following defects: 1. At the steps of the weld seam, no matter how the thickness of the coating film is adjusted, there is red rust. Point (according to the inspection standard: 20% copper sulfate, 10% dilute hydrochloric acid, 70% water solution, immerse the weld part in the solution, take it out after 3 minutes, and visually observe the blank area of ​​the weld under strong light), this is Chemical reaction, iron ions will replace copper ions in the incomplete or gapped weld area covered by the coating film, resulting in red rust spots on the part. This is a test method to check whether the repair coating of the outer weld is complete , this defect will cause appearance corrosion and container leakage; however, limited by the "natural" defects of the external repair coating process, the customers of the can factory have lowered the inspection standards for external repair coating welds, allowing abnormal Dense, non-linear corrosion spots

2. Environmental pollution. Because traditional coatings contain 70% solvents (30% solid content), most of the solvents are volatilized into the atmosphere (although there is a suction system), causing pollution; 3. Occupational health effects of employees The solvents of traditional paints contain toluene, xylene and other organic substances that have a significant impact on human health. These organic substances volatilize into the surrounding environment and cause adverse effects on the health of employees.

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