Improvement of accuracy of in-service strength evaluation simulation of cold forged parts

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06856
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Material processing/Microstructural control engineering
• Research Institution: Shizuoka University
• Principal Investigator: Hayakawa Kunio 静岡大学, 創造科学技術大学院, 教授 (80283399)
• Co-Investigator(Kenkyū-buntansha): 上森 武 岡山大学, 自然科学研究科, 准教授 (70335701)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 冷間鍛造 / 塑性力学

Outline of Final Research Achievements

A study was conducted to more accurately evaluate the strength of cold forged parts. First, an elasto-plastic constitutive equation for expressing the effect of load history during machining with high accuracy and an experimental method for identifying its parameters were studied. It was applied to the stainless bolt machining process and subsequent strength prediction. It was found that the proposed method significantly improves the strength prediction accuracy.
Next, a method for evaluating material properties before preforming was proposed by combining tensile, compression and shear tests, in view of the current situation that many cold forging materials are subjected to processing after preforming such as rolling and drawing. As a result, it was confirmed by analysis that the strength after the preforming-forging process was closer to that by experiments.

Free Research Field

塑性加工学

Academic Significance and Societal Importance of the Research Achievements

冷間鍛造の後，熱処理を経ないプロセスは，省エネルギー，低コストの観点から今後の需要の拡大が予想される．しかし，従来の部品強度予測手法では，加工工程中の負荷履歴の強度に及ぼす影響を正しく評価されていなかった．本研究は，その課題を克服する手法を明らかにしたもので，冷間鍛造部品の工程設計および強度評価のための新たな指針となる．
また，冷間鍛造に用いられる材料が既に予成形を受けていることは，周知の事実であるが，従来はそのことを無視して材料パラメーターを決めていた．本研究では，その影響を明らかにしており，今後決定される材料パラメーターについて合理的な意味づけを与えることができる．