Curved hull plates of marine vessels have been fabricated by skilled workers using line heating or flame bending method. Recently in Korean shipyards, mechanical bending such as multi-point press forming or die-less forming has been tried to replace the flame bending since the mechanical bending is more efficient than the flame bending. This paper discusses a multiple point pressing machine composed of a pair of reconfigurable punches in order to achieve the rapid forming of curved hull plates and presents how forming information is obtained from the given design surface. Although the mechanical forming can be efficient in the metal forming, springback after pressing is a phenomenon which must be carefully considered when quantifying the process variables. If the springback is not accurately controlled, the fabricated shell plate cannot meet assembly tolerance. In this study, the proper stroke of each punch is determined by an iterative process of sequential pressing and springback compensation from an unfolded flat shape to its given design surface. It is finally aimed to develop an integrated system that can automatically perform the springback compensation process and calculate strokes of punches of the double sides’ reconfigurable multiple-press machine. The deformation is numerically simulated by elastic-plastic FEA and springback compensation adjusts the offset of pressing punches from the deformation results and the design surface. For the practical application, a software configuration has been implemented to automatically calculate the strokes of pressing punches for the division multi-point forming work from the given design surface of a curved shell plate. The present study also provides several experiments of real forming processed by the suggested process.
Mechanical Bending Process and Application for a Large Curved Shell Plate by Division Multi Point Forming
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Hwang, S. Y., Lee, J. H., and C. Ryu. "Mechanical Bending Process and Application for a Large Curved Shell Plate by Division Multi Point Forming." Paper presented at the SNAME Maritime Convention, Bellevue, Washington, USA, November 2010. doi: https://doi.org/10.5957/SMC-2010-P28
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