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이강희,박용복,박태식 公州大學校工科大學生産技術硏究所 1999 論文集 Vol.7 No.-
The die for cold forging gets a very high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain a product with highly accurate dimension. Therefore, it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between a die and a product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lame's formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion, which can be applied in the die design for the product with accurate dimension.
Can-Flange 성형에서 금형형상에 따른 소재 유동특성
고병두,이하성,Ko, Byung-Du,Lee, Ha-Sung 한국금형공학회 2012 한국금형공학회지 Vol.6 No.2
The paper deals with an analysis of an extrusion process with a divided material flow in a combined radial - backward extrusion. We have discussed the influences of tool geometry such as punch nose angle, relative gap height, die corner radius on material flow and surface expansion into can and flange region. To analyse the process, numerical simulations by the FEM and experiment by physical modeling using Al alloy as a model material have been performed. Based on the results, the influence of fixed parameters on the distribution of divided material flow and surface expansion are obtained.
이지훈(Jihoon Lee),박주성(Jusung Park),윤태건(Taegeon yun) 한국추진공학회 2016 한국추진공학회 학술대회논문집 Vol.2016 No.12
로켓 추진기관 외피인 연소관은 고압, 고온 등 가혹한 환경에 견뎌야 하기에 고강도 소재가 이용되며, 주로 소성가공을 통해 제작된다. 소성가공에는 다양한 방법이 있지만 고강도 소재를 이용하기 때문에 공정이 까다롭고 균일한 기계적 특성을 만족하는데 어려움이 있다. 본문에서는 고강도 소재의 추진기관 연소관 공정개발을 위해 설계를 최적화하고, 고강도 소재인 마레이징강을 이용하여 열간후방압출공정을 통해 연소관을 제작, 기계적 특성을 확인하였다. Case in Roket propulsion has to endure harsh environments, such as the high-pressure and high-temperature. So, it widely makes of material that high degree of strength and toughness steel through plastic deformation processes. Also, it is hard to satisfying uniform mechanical properties due to material of high strength. In this study, it is optimization of manufacturing process for development of Rocket propulsion case with maraging steel through hot backward extrusion. Also we evaluated the mechanical properties.
김현수(Hyun Soo Kim),김용조(Yohng Jo Kim) Korean Society for Precision Engineering 2004 한국정밀공학회지 Vol.21 No.1
Traditional forging of a hollow T-shaped part has been applied to forge a solid T-shaped product from a solid billet and then to machine the hollow in that. In a case, a hollow T-shaped part can be forged by backward-extruding from a solid billet. In this study, four types of forging were suggested for manufacture of hollow T-shaped parts. Forging simulations for each of these forging methods were carried out to investigate folding defect, metal flow pattern, effective strain, and forging loads. Experimental works were carried out to be compared with the simulation results. Here, the ratio of the thickness of the hollow tube to that of the flange was selected to investigate a forging defect like folding.
에어 서스펜션 부품 개발을 위한 Al6061 소재의 후방 충격압출 일체 성형공정 설계인자에 관한 연구
김현성(HyunSung Kim),손원식(WonSik Son),황종일(Jongil Hwang),이진규(Jinkyu Lee),임성한(SungHan Rhim) 한국자동차공학회 2019 한국자동차공학회 부문종합 학술대회 Vol.2019 No.5
This study has conducted a forming analysis to establish design factors optimized for process of backward impact extrusion one-piece molding process. backward impact extrusion and gas bulging were performed, Finite element analysis was carried out assuming rigid-plastic and isotropic materials. In the backward impact extrusion analysis, The effective-stress distribution was higher than the tension test results. However, The materials fluidity was shown by the somewhat low critical damage value. It is expected that the shape completeness will increase if the thickness of the backward impact extrusion product decrease over the high temperature, high pressure and retention time in the gas bulging molding analysis.
A Study on the Backward Extrusion of Internal Spline
YongIl Cho(조용일),JongUng Choi(최종웅),Yuangen Qiu(추연근),Heayong Cho(조해용) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.9
Spline is a machine component using transmits rotating energy with grooves on internal of boss and external periphery of shaft. Internal spline is generally produced by machining process. However, to reduce manufacturing cost and save time, plastic deformation process such as backward extrusion is gradually adapted for spline production. In plastic deformation process, forming load, stress on tools and flow flaws should be taken into account to have sound products. For this purpose, kinematically admissible velocity fields for Upper Bound Method in backward extrusion of internal spline has been suggested, then forming load and relative pressure have been calculated. Internal spline forming experiments have been con-ucted under hydraulic press and the calculated forming load well predicts the load of experiment.
박세제(S. J. Park),고대철(D. C. Ko),김병민(B. M. Kim),김영환(Y. H. Kim),김동환(D. H. Kim) 한국소성가공학회 2013 압출 및 인발 심포지엄 Vol.2013 No.9
In hot forging of bushing for track-link parts, the extrusion height depends on the section of initial billet. So, in this paper, the section cutted by press has been consider to increase production of bushing in hot forging process. But, because of uneven surface, the metal flow is not uniform in backward extrusion process. It should be solve the problems caused by forward-backward extrusion process using the uneven cutting surface. The purpose of this study is to design the forward-backward extrusion for track-link bushing through the regular position method.
전기자동차용 알루미늄 밧데리케이스 충격후방압출공정 해석을 위한 마찰에 관한 고찰
김민철(M. C. Kim),이민철(M. C. Lee),이민철(M. C. Lee),전만수(M. S. Joun) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.10
In this paper, appropriate frictional law and conditions for predicting the cold impact backward extrusion process of an aluminum battery case of electric vehicles are presented. Some limitations in simulating the battery case backward extrusion process using finite element method are explained with emphasis on mesh effects and frictional phenomena. A hybrid frictional law is proposed to simulate battery case backward extrusion, based on the investigation into the frictional flow marks on the internal bottom.
Numerical and Experimental Analysis of Rotating Backward Extrusion as a New SPD Process
Xin Che,Qiang Wang,Beibei Dong,Mu Meng,Zhiming Zhang 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.12
Rotating backward extrusion (RBE) as a new severe plastic deformation technique is a continuous process to produce cylindricaltubes with fine grains and superior properties. In this study, the RBE process with an open punch was applied to theAZ80 alloy at 653 K, and the deformation mechanisms and the microstructure evolution were examined by the finite elementmethod (FEM) and thermal simulation experiment. The results showed that the effective strain of the RBE process was higherthan that of the conventional backward extrusion (CBE) process, and the strain increased with revolutions increasing. Thestrain improvement of the RBE process was related to the large cumulative plastic deformation imposed by the continuousrotation of the open punch. Furthermore, the extrusion load was reduced significantly in the RBE process comparing withthe CBE process, due to the change of friction stress and stress state of the materials. And the maximum load reduction ofthe FEM and experiment was 47.33% and 31.6%, respectively. The average grain size of the RBE sample could be reducedby up to 90% in the region A at 30 N compared with the CBE sample. The maximum increase in microhardness of the RBEsample relative to the CBE sample was 23% at 30 N in the region A. Therefore, the grain refinement and mechanical propertiesof the materials can be substantially improved by the RBE process.
포머의 냉간 후방압출 공정을 위한 금형 소재의 충격 특성 평가
노남수(N. S. Rho),박은기(E. K. Park),박효영(H. Y. Park),최정묵(J. M. Choi) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.10
This study is for the backward extrusion process of cold forging. In the backward extrusion process, the material flows in the opposite direction to the upper punch. The work piece is formed either in the cavity formed between the punch and die, or in the cavity of the punch. Backward extrusion is used to produce circular inside and outside diameters, squares with rounded corners, multiple outside diameters and multiple inside diameters. In this process, unique loads applied on the tool. This loads are reduce tool life cycle. We evaluate load applied to the tool using the FEM simulation, and impact property of materials for cold-forging die.