Since the tin solder used in the production process of soldered three-piece cans contains metallic lead (tin solder is generally composed of 98% of lead and 2% of tin), the packaged material is easily contaminated, so the soldering method Gradually eliminated, replaced by resistance welding and sticking. The production process of resistance welded three-piece cans and bonded three-piece cans is the same as the production process of three-piece tin cans. The two processes of processing cans and the combined process of can bodies and can ends are the same. The main difference lies in the processing of can bodies. .

(1) The resistance welding three-piece can body processing process is: can body blank cutting → slab feeding → double sheet detection and elimination → bending treatment → rounding → resistance welding seam → supplementary coating material → drying → Flange → can finish.

The process of full-automatic resistance welding for can bodies is as follows: The cut can body blank is placed in a slab crucible of a full-automatic can body forming a resistance welding machine, and sent to the feeding roller one by one by a vacuum suction device (if two Or the above billets are bonded together, then detected by the detector and excluded into the collector box), the single sheet slab is sent to the flexure roll for bending treatment by the feed roll, and then enters the molding apparatus to roll into a cylindrical can body, and the can The body is fed into a resistance welding machine, and after accurate positioning, resistance welding is performed. After the welded can body is coated with a weld, applied paint, dried, flanged and other processed, the can body is processed.

(2) Production of bonded three-piece cans. In the production of bonded three-piece cans, as long as the can seam welding equipment and process are changed to bonding equipment and processes, the rest of the equipment is the same as the process and welded three-piece cans. The bonding process consists of adhesive bonding process and adhesive lamination. Two kinds of process. 1 Adhesive laminating process is to apply nylon adhesive about 5mm wide at the seam end of the chrome plated steel sheet (or tin-free steel plate). When the can body is round, its adhesive part overlaps, and after heating (generally It is 260. C) It is fully pressed and allowed to solidify and cool, that is, the joint of the can body joint is completed. 2 The adhesive lamination process is to heat the film-like nylon adhesive and press it on both ends of the can body joint of the chrome-plated steel sheet (tin-free steel sheet) (that is, the breadboard side of the joint is to be breaded). Bonding with the outer end of the board and adhering the joints of the can body to complete the bonding of the can body joints.

Adhesion of three-piece cans using chrome-plated steel sheet, low raw material cost, saving tin, avoiding heavy metal contamination, full-plate printing, low energy consumption in production process, low operating cost; but poor heat resistance and water resistance, mainly used Solid or powdered product packaging.