Aluminum can forming process and tooling

Abstract: The drawing process of tank body, thinning drawing process and bottom forming process are analyzed, and some key technologies in the design and manufacture of molds related to these processes are studied.  Key words: cans;  Forming process;  Mold;  Thinning stretch

1 Quote

Aluminum cans occupy a considerable proportion in beverage packaging containers.  The manufacture of cans integrates the advanced technology of metallurgy, chemical industry, machinery, electronics, food and many other industries, and has become a microcosm of aluminum deep processing.  With the increasing competition in the beverage packaging market, for many canning enterprises, how to minimize the thickness of sheet metal in the production of cans, reduce the quality of single cans, improve the utilization of materials, and reduce production costs is an important goal pursued by enterprises.  Therefore, technological transformation and technological innovation characterized by light-weighting are quietly emerging.  The lightweight of cans involves many key technologies, among which can forming process and mold technology are very important aspects.

2 Tank manufacturing process and technology

2.1 Tank manufacturing Process The main manufacturing process of CCB-1A tank body is as follows: coil conveying → coil lubrication → blanking, stretching → tank forming → trimming → cleaning/drying → Stacking/unloading → primer coating → drying → color printing → bottom coating → drying → internal spraying → internal drying → tank mouth lubrication → necking → rotary compression neck.

In the process flow, blanking, drawing, tank forming, trimming, reducing, rotary compression diameter/flanging processes need mold processing, among which blanking, drawing and tank forming processes and molds are the most critical, the level of its process and mold design and manufacturing level, directly affect the quality of cans and production costs.

2.2 Tank manufacturing process analysis

(1) blanking and stretching compound process.  When stretched, the material at the edge of the billet forms a cup along the radial direction, so the element body in the plastic flow area is in a three-way stress state of bidirectional pressure and unidirectional tension, as shown in Figure 1.  Due to the action of the punch arc and the tensile die arc, the lower wall thickness of the cup is reduced by about 10%, and the mouth of the cup is thickened by about 25%.  The size of the arc at the corner of the cup has a great influence on the subsequent process (tank forming), if not controlled well, it is easy to break the tank.  Therefore, the blanking and drawing process must consider the following factors: the diameter of the cup and the tensile ratio, the punch arc, the tensile die arc, the convex, the concave die gap, the mechanical properties of aluminum, the friction properties of the die surface, the lubrication of the material surface, the drawing speed, the lug rate, etc.  The production of lug is mainly determined by two factors: one is the performance of the metal material, and the other is the design of the drawing die.  The lug appears at the highest point and thinnest point of the cup, which will affect the forming of the tank, resulting in incomplete trimming and increased scrap rate.