Flattening of a Fold in a High-strength Steel by Five Point Reverse Bending

高張力鋼板部材の5 点支持逆曲げ法による曲げ癖の矯正

High-strength steels are increasingly used in automobiles as a means of reducing auto body weight. However, in many cases, deterioration of dimensional accuracy is a problem. In particular, the increased springback of high-strength steels is a problem when press-forming parts. As a fundamental study, the relationship between springback and residual folds in formed parts was examined by experiments and calculation. In the actual manufacturing process, parts are formed in multiple steps, and the fold remaining in the work after bending must be flattened. While folds in mild steel are easily flattened using a flat die, it is difficult to flatten folds in high-strength steel using the same die. Although this is one cause of poor dimensional accuracy, little research has examined the problem of residual folds. In this study, two methods of flattening folds were examined by experiments and CAE, and a five-point reverse bending method was proposed. The results showed that flattening with a flat tool is insufficient to eliminate the fold in high-strength steel, but in contrast, a fold in a 980MPa high-strength steel sheet was completely flattened by five-point reverse bending.自動車の軽量化,衝突性能向上のために骨格部品のハイテン化が進められている.ハイテン材は成形性が低く浅い形状で成形後,次工程で壁を立てる工法が適用されるが,最初に曲げた部分が,曲げ癖となって残留する.本報告では,曲げ癖発生メカニズムの解明と,曲げ癖部と周辺を局所的に逆曲げする曲げ癖矯正手法を提案する.

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  • Accession Number: 01673488
  • Record Type: Publication
  • Source Agency: Japan Science and Technology Agency (JST)
  • Files: TRIS, JSTAGE
  • Created Date: Jan 31 2018 3:22PM