BEVERAGE CANS USING ALUMINUM ALLOY

Beverage cans using Aluminum Alloy

Beverage cans using Aluminum Alloy

Introduction

The parameters involved in the beverage cans manufacturing process have been analyzed by many authors. These parameters are used to determine the quality of the raw material before it is used to manufacture the cans. It is shown that the strain-hardening exponent together with the forming limit curve can predict whether the sheet metal will have a good draw ability throughout its length. It is also shown how much others parameters such as angle of the ironing die, friction coefficient and clearance between punch and ironing die influence the ironing force and consequently the manufacturing process. Deep drawing and ironing are the most frequently used manufacturing processes to produce thin-walled cans. Due to their importance these processes are currently the subject of many studies (Rubio et al., 2006; Campion, 1980; Chang and Wang, 1997; Danckert, 2001; Penteado, 2002; Courbon, 2003; Gotoh et al., 2003; Hackworth and Henshaw, 2000; Jianjun, 1994; Kammerer et al., 1995; Kampus and Kuzman, 1995; Ragab and Orban, 2000; Yanran et al., 1995). Danckert (2001) shows that there is a thickness reduction rate in which the ironing process becomes unstable. This leads to a variation of thickness along the can in the circumferential direction. These problems are generally solved in the industry by trial and error, with changes in the material geometry. Over the years, can thickness has diminished without reduction in mechanical resistance followed by added density (Courbon, 2003). However, there are related problems such as the reject rate of defective cans during manufacturing, where for a given roll coil, there is a higher rate than for others. This, however, fromthemanufacturer's point of viewis very difficult to predict, since there is no normalized method or equipment for this purpose.

Analysis of the manufacturing process of beverage cans using aluminum alloy

The strain-hardening exponent, strain-hardening coefficient and plastic strain ratio were obtained using a tensile test to construct the stress curve versus true strain (DIN, 1991). Based on this curve, the flow curve is obtained that will supply the values of the strain-hardening exponent and strain-hardening coefficient. The aluminum beverage can consists of two pieces — the can body and the can end (or lid). The manufacturing process begins with coils of aluminum. Each coil typically weighs about 25,000 pounds and, when rolled out flat, can be anywhere from 20,000 feet to 30,000 feet long and five to six feet wide.

The aluminum coils are loaded onto an "uncoiler" at the beginning of the can making line. The uncoiler unrolls the strip of aluminum and feeds it to the lubricator. The lubricator deposits a thin film of water-soluble lubricant on both sides of the aluminum sheet. Lubrication allows the metal to flow smoothly over the tooling surfaces during the forming processes that follow. Metal forming begins in a large machine called a cupping press. The press cuts circular discs from the aluminum sheet and forms them into cups. The cups drop from the press onto the cup ...