Study On The Key Technology Of Thin-Walled Aluminum Can Forming With Variable Thickness And Large Tapers

Monobloc aerosol aluminum can is wide applicated in the packaging industry because of its good gas barrier properties, excellent moisture resistance, shading performance and easy printing etc.With the material cost increasing, it becomes the purposes for many factories that to lower the weight of a single can, to reduce costs and to increase profit. At the same time, as people pursue product's personalize,diversification,quality etc., large taper packaging cans are increasing, which has become an important means to promote production.Therefore, it is the packaging industry's development trend that how to product the new products which are lighter,saving in material,more environmental protection and good visual effects. Accordingly, in this paper the variable tube thickness optimization and large taper aerosol aluminum can forming are completed. The following are the main content of the paper.Die surface optimization of variable thickness backward extrusion.The variable diameter backward extrusion die was developed, in which the surface structure is different from the traditional cold extrusion concave. using it the variable thickness aluminum tube can be formed only once.Backward extrusion finite element model of ladder,linear,cosine,elliptical transition surface is established. According simulation, the influence of different transition surface on extrusion load,metal flowing and stress field are studied, it is presented that elliptical transition surface is better than others. It can reduce the warping phenomenon of variable thickness tube.Discusses the influence of process parameters on the variable thickness backword extrusion, the optimal process parameters were presented.The theoretical analysis of large taper nosing deformation. Mechanical analysis is carried out for conical die nosing and circular die nosing by axisymmetric revolving-shell membrane theory. Then, mechanical models of conical die nosing and circular die nosing with straight pipe were established. Based which the comparison between two types of die structure was carried. The results show that: circular nosing- mold is very effectiveon on lower nosing force,controlling the deformation,increasing the tube nosing limit (buckling occurring at the cylinder). Based on the loading models of conical die nosing, the conversion conditions of conical nosing deformation was studied, Critical half-angle is presented as 50-55 degrees. The study of exit free bending in nosing deformation. Through studying the exit bending of the thin-wall tube nosing, the radius formula of the exit free bending was presented. It is proved by experiment and simulation that the bending radius decrease with half- angle and increase with the diameter of export terminal and tube thickness. This formula was demonstrated practicality by part forming and can be served as guidelines for process-planning and die designing.The forming process analysis of large taper aluminum tube and numerical simulation study. Large taper aluminum forming process was established and the new type nosing die were developed. For the characteristics of thin-wall and large half-angle,circular structure was introduced in the die mouth. The forming process can be divided into nosing stage and rolling stage. The main purpose of nosing stages were to form the half-angle and nosing factor, provide the blank of rolling. Roll forming stage provide the final part shape. Finite element simulation and the parts forming verify the forming process.