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Hitachi

Corporate InformationResearch & Development

October 21, 2014

Report from Presenter

Metal Forming 2014 (15the International Conferences) was held in Palermo, Italy during September 21- 24 2014. Metal Forming Conference series was organized biennially since 1974. The aim of the Conference is to provide a forum for academics and industrialists to discuss and disseminate recent developments, innovations and advances in metal forming processes. This year, almost 200 papers from about 20 countries were submitted [1].


Fig. 1 About structural channels
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Hitachi's Yokohama Research Laboratory made a presentation entitled "Influence of Roller Shape on Deformation Behavior in Roll Bending of Structural Channels."

Structural channels are members that have the same shape in cross section over the entire length, and they are widely used in building materials and frame members for automobiles, as shown in Fig. 1. Structural channels are sometimes used as bent parts. However, bending of structural channels with complicated sectional shapes can cause cross-sectional deformation, wrinkling and twisting. There are several ways to bend structural channels. For example, stretch bending, rotary-draw bending and press bending. Each method has its own advantages. However, the disadvantage of all of these methods is that a different die is needed for each bending radius. This means that the die cost is high. For this reason, a more flexible forming method is required, especially for diversified small-quantity products.

Fig. 2 shows the principle of roll bending. Flexible forming is possible because it can manufacture products with various bending radii by adjusting the amount of displacement of the side-rollers. For this reason, roll bending is a useful technology for manufacturing of a wide variety of products in small quantities. However, Irregular deformation is likely to occur because the workpiece is not well constrained compared with other bending methods. So, we conducted a finite element analysis (FEA) to investigate the effect of the roller shape on the deformation behavior of structural channels during roll bending.


Fig. 2 Principles of roll bending
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Fig. 3 Finite element analysis model
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Fig. 3 shows the FEA model. Dynamic explicit FEA was used to numerically simulate the roll bending process. The main evaluation item is the cross-sectional shape of the structural channel. The evaluation positions are the web and the flange regions. These parameters were evaluated using a spring-back analysis. By using the analysis model as shown in Fig. 3, we investigated not only the Influence of roller shape on deformation behavior in roll bending of structural channels but also the deformation mechanism [2].

It will be possible to bend of structural channels with more complicated sectional shapes, by clarifying the deformation mechanism of a simple shape. In Yokohama Research Laboratory, we will continue to contribute to the development of high-precision processing technology by clarifying the mechanism of deformation using finite element analysis.

References

  • [1] Metal Forming 2014 Website (Final Program)
    http://www.metalforming2014.com/doc/MF_FinalProgram.pdf
  • [2] Y. Murasato, T. Makiyama, T. Teramae, Influence of Roller Shape on Deformation Behavior in Roll Bending of Structural Channels, Key Engineering Materials (Volumes 622 - 623), 2014, P936-942
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