Technology and method of coating and printing inside metal container（1）
knowledge of steel pail metal bucket
1. Coating principle
Coating the inner surface of the metal container is to print and coat the appropriate paint on the smooth surface of the thin steel plate with a roller coater before the thin steel plate is cut into barrel blanks to form a uniform, thickness-controllable coating. The coating machine can independently carry out the coating operation through its own feeding device, and can also be matched with the iron printing machine to form a printing and coating operation line.
The rotating stainless steel feeding roller is half immersed in the feeding tray, and the paint brought up is transferred to the rubber cylinder through the uniform roller. There is an embossing cylinder under the rubber cylinder, which is equipped with a gripping device. When the thin steel plate runs to the front of the rubber cylinder, the teeth of the impression cylinder hold one end of the iron sheet, and the rubber cylinder and the impression roller cooperate to push the iron sheet through to complete the printing operation. The thickness of the coating is controlled by the feed roller, leveling roller and the gap between the rubber cylinder and the impression cylinder. Due to the gap between the thin steel sheet and the sheet, a small amount of paint is taken away by the impression roller. Use a scraper to scrape off the impression cylinder (avoid the material on the back of the iron sheet), and the scraped paint flows into the receiving tray, and after being collected, it flows back to the storage barrel through the conduit and is recycled.
The welded part of the side seam of the metal container cannot be painted with paint, otherwise, the barrel blank will easily break through the side seam during the high-frequency resistance welding process and cause waste barrels. Therefore, the operator should make grooves on the rubber cylinder according to the printing area of the metal container. The paint is applied and printed on the tinplate sheet through the slotted rubber roller, and the blank iron left at the slotted part is the high-frequency resistance welding part of the empty barrel.
We realized in the actual operation that the size of the slot should be 1-2mm wider than the actual welding gap size so that the printed gap size can meet the empty barrel welding requirements.
The coated iron sheet is transported to the drying room through the conveyor belt and is cured at a high temperature in the drying room driven by the circulating chain. The drying room is generally divided into three parts: the first part is to preheat the iron sheet to the baking temperature; the second part is to bake at a constant temperature; the third part is to fully cool the iron sheet. The whole baking time takes 10-15 minutes. After that, the iron sheet is unloaded by an automatic unloading machine, and the coating is transferred to the barrel making process after passing the inspection and physical and chemical tests.
