TPT January 2007

A two-stage solution to an optimised production result

Given the fact that a full finite element computation is not a matter of minutes, even with the speed of today’s computer systems, a two- stage solution has proven its worth in actual practice. This consists of preliminary optimisation through a fast computing approach by Copra DTM (calculation of plastic strain values), and subsequent validation of the complete tool set by Copra ® FEA RF (finite element analysis). An optical scanning tool for roll and profile cross-sections is available for the analysis and improvement of roll tooling already in use in production. It delivers digitised tool contours that allow quality inspection of roll tools parallel to production and FE analysis of the forming process. Copra ® FEA RF provides the user with important data about possible problem areas in metal forming. The software generates values particularly relating to material strain and inner stress or quite simply to the forming forces or moment. Copra ® FEA RF is a decisive aid in understanding the rollforming process, and in this way contributes to improved quality. A number of examples are illustrated in figures 4, 5, 6 and 7. fi Figure 4 : ‘Air bending’ in a station. There is the risk of marks on the outside surface of the tube, caused by the point contact at the bottom roll. The part with the larger radius than designed must be formed later. This means additional work for the fin stations Simulation of a tube forming process with Copra ® FEA RF

› Figure 6 : Investigation of the V-angle. The V-angle is important in defining the position and geometry of the welding equipment

› Figure 7 : Copra ® FEA RF: thermomechanical coupling for simulation of the welding process; heat distribution model according to Scott 8

Practical example – wall thickness distribution The below simulation shows the forming of a welded tube, and the results are compared to practical values. The example taken is a W-forming of a 60mm steel tube with 27 stands. The thickness of the metal is 1.5mm.

fi Figure 8 : W-forming of a 60 x 1.5mm tube 6

fi Figure 5 :

Verification of tube quality: a poor and a better example

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J ANUARY /F EBRUARY 2007