Numerical Simulation On Hull Plate’s NO-pair Multi-press Head Stamping Forming

In shipping manufacture, Line-heating is the generally used method in processing complex double curvature of the hull plate shipyard in shipyard at home and abroad.This method has been one of shipbuilding problem because of low production efficiency, labor strength and backward production mode.No-pair punch loose forming method with square press heads(NPF) has been proposed and used,which provide a new way to realize the ship plate processing mechanization and auto-mation.This method is a kind of sheet stamping forming technology based on discrete mould,which realize the various surface of reconfigurable forming. Its forming effect is much better than traditional whole mold.In industries field such as shipbuilding,it will have a good application prospect.Numerical simulation method in the research on the laws of material plastic deformation have strong superiority,numerical simulation of no-pair punch loose forming method with square press heads can intuitively observe plastic deformation under the law of his method and various problems appearing in the complex sheet metal forming,which can also predict the formability of sheet metal.This will have a great reference significance for improving processing craft and perfect pressure head design.This article use the no-pair punch loose forming technology with square press heads as the foundation, which use sail surface and saddle surface as the research object. Useing sheet metal stamping forming analysis professional software DYNAFORM for the finite element analysis of sheet forming.According to the special structure characteristics and forming technology of forming principle established the finite element model of sheet metal stamping forming.Research numerical simulation loading forming process and the key problems of the finite element analysis.Through the analysis of forming resultst,we find that the same curvature of sail doubly curvature stamping effect is very good,but the different curvature of saddle doubly curvature exists a small defects.This simulation basically realized the pressure head swing around the base plate of spherical with the surface change,which also raalized the reconfigurable tool.And the forming limit digram displays that the sheet metal using this stamping technology have a very good formability.The actual processing defects appears in forming, numerical simulation can real reaction comes out.Combined with experiment, we find the contrast of theory calculation results consistent with the experimental results, the error is very small.Numerical simulation analyse the forming effect of sail and saddle surface which have the same thickness and curvature radius, respectively use whole mould forming and no-pair punch loose forming method with square press heads,we find the forming quality of use the latter method is significantly better.This is attributable to the unique pressure head structure design of loose square pressure head forming-the pressure head swing around the base plate of spherical with the surface change.Respectively analysis of the wrinkling phenomenon among the same curvature radius but different thickness and the same tickness with different curvature radius in the process of sail surface forming. Simulation found that for small curvature plate,thickness among1-4mm wrinkling will occur in the edge area, for thickness more than5mm sheet metal basicly won’t happen wrinkling phenomenon.Under the same thickness,the wrinkle will be more obvious when the curvature get largeer.Based on shell element,the springback simulation of sail plate can predict its springback to a certain extent.