Integrative Sheet Metal Processing CentreCopyright: Image: Thilo Vogel
Flexibility is a key issue in modern production technologies. In recent years, most industries experience a rising demand for customized products. The manufacturing of customized products creates opportunities for economic growth and secures international competitiveness. Modern production systems have to be sustainable and ensure a high product quality. At the same time, they have to allow for an economic and flexible modification of the process. Hence, concepts that meet the target “First Time Right” need to be developed in order to save time, money and resources during the development and production of the product. The rapid development of industrial sectors processing sheet metal parts, such as the automotive industry, requires flexible production processes adapted to their needs. That way sheet metal parts which are adjusted at its best to their functionality could be produced cost-efficiently.
Challenges in Application
The establishment of a both flexible and resource-efficient production represents a major challenge for production engineers. Customized sheet metal parts are usually characterized by a high complexity and low production volumes. Common sheet metal forming processes, e. g. deep drawing and stretch drawing, are in many cases not capable to meet the requirements of the customers. Furthermore, a specific forming tool is needed for every single geometric variety. The production of forming tools, however, is expensive and time-consuming. Another issue is the processing of different material grades. Especially the aerospace industry uses high strength metals, such as titanium alloys. The possibilities of forming these materials with common sheet forming processes at room temperature are limited. Combining different technologies renders the manufacturing of components made of high strength materials with complex geometries possible.
ApproachCopyright: Image: Thilo Vogel
In Incremental Sheet Forming (ISF) the final part is formed by a sum of localized plastic deformations. A generic forming tool moves along the contours of the desired part. The forming process can be supported by a full or partial die. Since the forming tool is independent of the produced geometry, this production method is excellent for the manufacturing of prototypes and small production volumes. A combination of stretch drawing and ISF expands the production possibilities of the Integrative Sheet Metal Processing Centre. The first process step is stretch drawing followed by the incremental shaping of geometric details. Due to the combination of these two processes the comparatively large process time of pure ISF can be reduced significantly. Additional advantages in the process combination of stretch drawing and ISF are the homogenization of the sheet thickness distribution and the increased geometric accuracy of the entire part. Hence, more complex geometries can be produced within a shorter time. In general, ISF is characterized by low forming forces due to the locally limited forming area and a low tooling effort. These features turn ISF into an economic alternative for industrial sectors with specific product requirements, such as the aerospace industry. Many geometric varieties, small production volumes, large parts and the use of high strength materials are characteristic for this industry. Typically, titanium alloys which are difficult to form at room temperature, e. g. TiAl6V4, are used. Their formability can be increased by a local heating of the forming area during ISF. To realize ISF of high strength alloys, a laser beam is integrated into the Integrative Sheet Metal Processing Centre. The two introduced hybrid technologies enable a flexible production of sheet metal parts with an extended component and material spectrum. The parts are produced in consecutive processes by combining different technologies in one single production unit. That allows the customized production of geometrically accurate components made of sophisticated materials. Simultaneously, stock costs and set-up times can be reduced.
The integration of different technologies and manufacturing processes is challenging. The different technologies have to be mounted in a limited workspace and linked within the control unit. Furthermore, complex forming strategies have to be implemented to apply the combination of stretch drawing and ISF. Another task is the temperature regulation of laser-assisted ISF. During the process neither blank nor forming tool should overheat. The optimal process temperature for a specific material has to be analyzed and kept constant during the forming
process. Thus, the temperature of the locally formed area has to be measured and controlled precisely. Suitable solutions have been developed and tested on industry related components.