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권용남(Yong-Nam Kwon),김남용(N. Y. Kim),김국주(K. J. Kim),이진모(J. M. Lee),이영선(Y. S. Lee) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
본 연구에서는 대형단조품 열간단조에 미치는 단보지의 영향을 조사하기 위하여 실제 실험과 유한요소해석을 실시하였다. 본 연구에서 수행한 열간단조 조건내에서는 열간단조비의 영향이 크게 발생하지 않는 것을 확인할 수 있었다. 이와 함께 서영 및 냉각공정의 해석을 통하여 실제 단조품의 미세조직을 예측하는데 활용할 수 있음을 확인하였다. Hot forging characteristics of S355NL steel for wind mill parts have been studied in the present study. Firstly, three different sized billets were prepared and forged at the temperature of 1250℃. Forged microstructure as well as mechanical properties was characterized to verify the effect of forging ratio. Also, a conventional finite element analysis consisting of both forging and cooling of forged billets was carried out to simulate forged part’s microstructure numerically. These data were compared with thermodynamic calculation results in the end.
권용남(Yong-Nam Kwon),김상우(S. W. Kim),천세환(S. H. Chun),박은수(E. S. Park),차달준(D. J. Cha) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Cold flow forming was investigated with both forming experiment and numerical analysis. Flow forming is a kind of incremental forming processes which uses a roller to form a cylindrical part with repeated turning of both roller and sheet. This process has several advantages over conventional forming methods to fabricate cylindrical parts. One of the advantages is that flow forming enables a quite high degree of near net shaping of a cylindrical part. Also, it usually increases mechanical properties such as fatigue strength due to strain hardening which occurs during the process. In the present study, optimum process parameters were tried to be sought by both using a series of experiments and numerical analysis.
권용남(Yong-Nam Kwon),김상우(S. W. Kim),구본규(B.G.Gu) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
A cold forging process for hollow shaft shape was designed by using finite element method in the present study. Hollow shaft products have been widely used for auto transmission parts and other applications. Hollow shaft has been usually fabricated with gun drill machining to lower the weight of final product. However, more cost efficient ways to manufacture hollow type product has been sought since conventional machining usually costs quite much. There have been several ways to make hollow type forgings such as rotary swaging and rotary forging, which cost a lot of initial machine cost. In the present study, a conventional cold forging process was designed to make hollow shaft product using several step forgings.
권용남(Yong-Nam Kwon),김상우(S. W. Kim),김봉준(B. J Kim),박은수(E. S. Park),차달준(D. J. Cha) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
In the present study, flow forming process for the manufacturing hollow shape transmission component was investigated with both forming experiment and numerical analysis. Flow forming is a kind of incremental forming processes which uses a roller to form a cylindrical part with repeated turning of both roller and sheet. Hollow type parts can be effectively flow-formed with the use of tube as starting material compared to a usual sheet since an average strain accumulation during whole flow forming process is much lower in the case of tube as staring material. However, it is still hard to flow-form high strength steel sheet in a tool path. Therefore, it is quite usual to distribute the amount of thickness reduction or strain into several tool paths. In the present study, optimum processing paths were tried to be sought by both using a series of experiments and numerical analysis. Also, trial sample was examined to verify flow forming process design.
권용남(Yong-Nam Kwon),김다영(Da Young Kim),구본규(Bo Kyu Gu) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
A cold forging process for hollow shaft shape was designed by using finite element method in the present study. Hollow shaft products have been widely used for auto transmission parts and other applications. Hollow shaft has been usually fabricated with gun drill machining to lower the weight of final product. However, more cost efficient ways to manufacture hollow type product has been sought since conventional machining usually costs quite much. There have been several ways to make hollow type forgings such as rotary swaging and rotary forging, which cost a lot of initial machine cost. In the present study, a conventional cold forging process was designed to make hollow shaft product using several step forgings.
권용남(Yong-Nam Kwon),김태옥(T. O. Kim),김국주(K. J. Kim) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.10
Ring rolling process was designed for wind mill forging part using 18NiCrMo14-6 steel. Dimensional accuracy as well as microstructure during ring rolling was needed to be sought for a successful forging part in the present study. For this purpose, both physical and thermodynamic properties were calculated with using commercial software, Jmat-Pro. Also, high temperature compression tests were performed to get deformation characteristics of 18NiCrMo14-6 steel. These compression data was interpreted under the dynamic deformation theory. Using these data, finite element analyses were carried out for a proposed ring rolling process. After finite element simulation, a modified process was proposed to hider ring rolling defects.