Basic principle of inner coating of tinplate cans

The coating on the inner surface of the cans was coated with a suitable coating on the smooth surface of the tinplate using a roller coater before the tin cans were cut into can body blanks to obtain a uniform, thickness-controllable coating. The coating machine can perform the coating operation independently by its own feeding device, and can also be combined with a printing machine to form a printing and coating line.

The rotating stainless steel feed roller was half immersed in the supply pan and the stripped paint was transferred to the blanket cylinder via a screed roller. There is an impression roller underneath the blanket cylinder. When the tinplate skin runs to the rubber roller, the pressure roller squeezes one end of the iron plate, and the rubber roller and the impression roller cooperate to push the tinplate through and complete the painting operation. The thickness of the coating is controlled by the feed roller, the screed roller, and the gap between the blanket cylinder and the impression cylinder. Due to the gap between the tinplate sheet and the sheet, a small amount of paint is taken away by the impression cylinder. The squeegee is used to scrape the squeegee clean (avoiding the back surface of the iron coating). The scraped coating material flows into the splicing tray and is collected and returned through the conduit to the storage drum for recycling.

Canned seam welding can not be coated with paint, or can body billet in high-frequency resistance welding process easily break through the seam and cause waste cans. Thus, the operator should slot the blanket cylinder according to the application area of ​​the can container. The slotted rubber roller of the paint is applied on the tinplate. The blank iron left in the slotted part is the high frequency resistance welding part of the empty can.

We realized in actual operation that the size of the slot should be 1~2mm wider than the actual size of the blank, so that the size of the blank to be printed out can meet the requirements of the empty cans.

After the coated tinplate is transported to the drying room via a conveyor belt, it 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 baking temperature; the second part is constant temperature baking; and the third part is to fully cool the iron sheet. The whole baking time needs 10 to 15 minutes. After that, the iron sheet was unloaded by an automatic plate unloader, and the coating was transferred to the canning process after passing the inspection, passing the physical and chemical tests.