| In current manufacturing for can making, a time consuming and therefore expensive process involves the spray of food-contact safe polymer coatings onto the can interior before filling. This process can be eliminated by using a polymer pre-laminated metal workpiece as long as the polymer survives the manufacturing operations involved in can making. The most demanding operation in can making is the ironing process because of the high pressures involved as well as the necessary generation of new surface. Previous research has shown that polymer laminated steels are quite stable and survive ironing operations with proper tooling geometry at room temperature and very low ironing speeds. However, much higher speeds are industrially relevant, suggesting elevated tooling temperatures need to be investigated as well. The intimate contact between the hot tooling and workpiece may soften or even melt the polymer. This dissertation investigates the thermal effects of hot tooling under realistic conditions in order to develop polymer laminated steel into a robust alternative can stock.; Ironing of polymer laminated steels with heated tooling was examined experimentally with an ironing simulator. Tooling temperature and ironing die angle are identified as the two most important variables affecting the formability of the coating. Higher die angles allow larger thickness reduction but lower coating survivability. Elevated tooling temperatures have an adverse influence on both formability and survivability of polymer coated steels.; Upper bound models of coated ironing were also developed for theoretical analysis and to provide design guidelines. The initial coating thickness was identified as a critical variable for successful ironing. It is also suggested that the coating shear strength should be used as an input in the ironing models. Therefore, single asperity plowing experiments in an atomic force microscope were conducted to characterize the mechanical properties of those thin polymer films.; To study the heat transfer in coated ironing, finite element models were developed using the commercially available software package, ABAQUS. A number of industrially relevant geometries and speeds were considered in this analysis to allow evaluation of process parameters that lead to successful ironing. |
