Some current development trends in metal-forming technology

Abstract

Various trends in metal-forming technology which will change future plant construction and production technology are already becoming apparent. The report describes the shortening, flexibilization and integration of a number of processes. Moreover hollow structure technologies become more and more interesting for innovative production. Furthermore FEM-simulation and optimization, also reported on in the paper, are increasingly important tools for the development of new or improved processes and plants. In view of the need to minimize production costs, to increase environmental compatibility and to manufacture products to a defined quality standard, long, complex processes should be shortened as far as is possible or necessary. In the field of strip production, mention should be made of the development of thin slab technology and thin strip casting, in which certain manufacturing steps are eliminated completely. For formed parts, possible methods for shortening the process include forming in the solidus-liquidus range (thixoforming). Another possibility is a combination of forming with heat treatment. Shorter process chains often mean more favourable mechanical properties for the products and hence new applications. Against a background in which forming processes are becoming more flexible in order to enlarge the spectrum of products, it is necessary to use flexible forming units with adaptable links to preceding and succeeding steps as well as universal dies and intelligent controls. For example, robot-manipulated open die forging allows reproducible manufacture of complex forgings with relatively small allowances. A variable rolling gap in the rolling process means that sheet metals can be produced with a defined longitudinal thickness profile matching the load case for the subsequent component. The integration of different production processes also paves the way for new approaches. Existing process limits can be extended and the final properties of components optimized by using partial heating methods during or directly after forming and by coupling forming processes with parting or joining techniques. A promising approach in the field of innovative lightweight construction is the systematic use of hollow structures; new processes for generating cavities and production techniques for processing the new hollow structures are being developed. Apart from suitable tests, physical and numerical simulation can be used to optimize existing or develop new methods of manufacture. Physical simulation may be especially successful in solving questions of material flow. A new material flow simulator is presented. Numerical simulation is used especially for quantitative analysis of local process variables; methods have recently been developed for taking the modification of structure during the forming process into account.