J.S. Lepistö’s research while affiliated with Lappeenranta – Lahti University of Technology LUT and other places

A novel manufacturing process of lightweight cell structures is based on laser cutting and punch pressing techniques. The process based on turret punch press with laser is flexible and, therefore, the cell structure is easy to tailor. The punch press process enables even the cost effective one-off production. The new kind cell structure is considerably simpler than conventional ones. The studied cell structure consists of two plates. Both plates are manufactured using punch pressing and laser cutting. Truncated cones are formed with forming tools of a turret punch press. The flat shape of truncated cone is essential for joining the plates together. Joining methods to be used depend on the nature of the loads and other requirements. This manufacturing method gives an opportunity to tailor the cell structure. For example, the rigidity of the cell structure can be altered by changing the number and location of the embosses. Furthermore, the shape of the embosses can be varied, as well as their height, width and length. This feature makes it possible to manufacture even tapered cells in thickness direction. Formed cell structures are rather new constructions. Therefore, these kinds of structures need studying. The aim of this work is to study the behaviour of a cell structure subjected to compressive load. Main results of the study will be presented in this paper.

A novel manufacturing process of lightweight cell structures is based on laser cutting and punch pressing techniques. The process based on turret punch press with laser is flexible and, therefore, the cell structure is easy to tailor. The punch press process enables even the cost effective one-off production. The new kind cell structure is considerably simpler than conventional ones. The studied cell structure consists of two plates. Both plates are manufactured using punch pressing and laser cutting. Truncated cones are formed with forming tools of a turret punch press. The flat shape of truncated cone is essential for joining the plates together. Joining methods to be used depend on the nature of the loads and other requirements. This manufacturing method gives an opportunity to tailor the cell structure. For example, the rigidity of the cell structure can be altered by changing the number and location of the embosses. Furthermore, the shape of the embosses can be varied, as well as their height, width and length. This feature makes it possible to manufacture even tapered cells in thickness direction. Formed cell structures are rather new constructions. Therefore these kinds of structures need studying. The aim of this study is to research what factors are essential for manufacturing techniques of these structures. Main results of the study will be presented in this paper.

The focus of this paper is on a non-cutting, single stroke clinching method that produces an axisymmetric joint. Here, a simple procedure based on testing and calculation of volumes is introduced. This paper also presents the clinching parameters for several tool combinations, based on the proposed procedure, as well as the results obtained by simulating the clinching process for two tool combinations using finite element analysis. The numerical simulation was performed in order to verify the proposed procedure, although both methods can be used either separately or together to establish optimal clinching parameters. Furthermore, the suitability of the analysis software for this kind of simulation and the kinds of problems that can be encountered in this procedure are discussed here.