Papers by Author: Michael Trompeter

Abstract: The development of manufacturing methods for producing plastic-metal hybrid structures has already opened new possibilities for lightweight design. Contrarily to the existing technologies i.e. Insert, Outsert and Hybrid Technology, the new forming process “Polymer Injection Forming” (PIF) offers the advantages associated with injection moulding technology and hydroforming technology in a way that hybrid structures can be produced in a single step. The polymer which is used as pressure medium in a melted state to form geometrical features in the sheet metal remains as a functional part in the final hybrid structure. This paper focuses on the experimental investigation of Polymer Injection Forming. Particularly, the interaction between process parameters of injection moulding including injection pressure, cavity pressure, volume flow rate, melt temperature and the resulting part properties e.g. shape and strain distribution of the sheet metal structure from the preliminary results are discussed. The experiments comprise the bulging of a (free form) dome geometry and simple cup geometry of Aluminium and steel sheets by using thermoplastic Polypropylene (PP) as working medium.

Abstract: This paper presents a sectionwise hydroforming technique for manufacturing of large-area multi-cell sheet metal structures in terms of hump plates. The sectionwise hydroforming technique allows production of hump sheets with variable width and length. The hump plates are based on hexagonal hump geometry. The hump height is optimized for the application as a partition wall in light utility vehicles. Manufactured hump sheets feature a high contour accuracy which allows joining of two hump sheets to a large-area hump plate (up to 1,800 x 2,000 mm). The hump plates have been successfully tested in a load test which proves their potential for light utility vehicles.

Abstract: In this paper, the use of partially or tailored cladded blanks is proposed for the production of multifunctional lightweight components. Therefore, the non-joined sheet areas will be formed to hollow structures by hydroforming subsequent to the partial cladding operation. The paper presents results of research work on the production processes and potential applications of partially cladded blanks in the field of thermal engineering and automotive engineering. Furthermore, it is focused on possible developments regarding the use of multiple materials and process combinations for sophisticated applications e.g. in the field of lightweight constructions.

Abstract: A promising approach to control the material flow within deep drawing and workingmedia based forming processes is the structuring of the tool surfaces in the contact zones between workpiece and die. In order to obtain a sufficient and an optimised material flow respectively – especially for non-symmetric or non-uniform workpiece geometries – a locally adapted distribution of surface structures is a practicable solution. The macroscopic, and also the microscopic surface structures can be manufactured sufficiently by means of a high-speed cutting process. The shape of the tool surface structure has a significant influence on the tribological conditions between workpiece and die. To adjust the surface structure distribution to the required material flow distribution, detailed knowledge about the correlation of the material flow from the tribological conditions between sheet and the forming tool is required. A further innovative approach, particularly for decreasing the friction coefficient, is the use of an innovative hydrostatic pressure system using fluid ducts. Its functional principle is based on the reduction of the contact shear stress at the sheet surface in the contact zone with the forming tool by means of locally applying a hydrostatic fluid pressure. To obtain information about the correlation of the material flow from the tool surface structures and from the parameters of the hydrostatic pressure system respectively, fundamental investigations have been carried out. In order to optimise the material flow, these toolbased approaches can be used as stand-alone solution, or in addition to other systems. If the surface structures and a hydrostatic pressure system are used in combination with the multi-point blank holder, which has already been qualified for the high-pressure sheet metal forming (HBU), a powerful system for the material flow control is available.