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안규희(Ku-Hee Ann),강종훈(Jong-Hun Kang),허수진(Su-Jin Heo),신태수(Tae-soo Shin),조해용(Hae-Yong Cho) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.9
Recently, as the weight reduction of vehicles has been actively progressed, parts developed using aluminum 60XX series from existing steel materials are increasing. In this paper, the bushing used for the front frame rail, which is one of the parts for fixing engines and other parts in automobiles, was changed to an aluminum material of the Al60XX series, and it was intended to be produced by applying of cold forging method. The bushing is a part that secures the engine frame, and in order to produce it by cold forging, the molding limit is predicted through process design, and a multi-stage process is designed through finite element analysis. In addition, in order to verify the feasibility of the designed forging process, the limits of the multi-step process were verified based on the Cockcroft Latham theory, and the crack and overlap of the actual forging work were predicted and improved.
안규희(Ku Hee Ann),조해용(Hae Yong Cho),허수진(Su Jin Heo),강종훈(Jong Hun Kang) Korean Society for Precision Engineering 2019 한국정밀공학회지 Vol.36 No.12
Process and die design of cold forging for the asymmetric part, engine mount adapter has been studied. Forging of the asymmetric part frequently causes die failure because of the high forging load and local stress concentration of the die. Thus, performing process design of cold forging to minimize forging load is required. Preform for the engine mount adapter was chosen based on the forging load and filling rate of forgings by the finite element analysis. In the die design, number of stress rings, interface radius, and relative interference were investigated in several cases with maximum principle stress by the finite element method. The shape of the die was determined by comparing the load changing the radius of the flange area. Also, the life of the designed die was calculated using the Goodman theory by cyclic fatigue loading. As a result, it was confirmed that the calculation life and results of the test were identical. In this study, it is verified that stress concentration and fatigue life should be considered simultaneously in the design of cold forging die for the asymmetric part.
유한요소법을 이용한 스프링와셔용 경강선재 롤인발 공정설계
정동환(Dong-hwan Jung),송현정(Hyun-jung Song),김창일(Chang-il Kim),김종희(Jong-hee Kim),박명수(Myung-soo Park),김지훈(Ji-hoon Kim),조해용(Hae-yong Cho) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.10
와셔는 볼트와 너트 사이에 장착되는 기계요소로서 체결물 간의 접촉압력을 낮춰주고 동시에 풀림을 방지한다. 둥근와셔, 사각와셔, 스프링와셔 등 다양한 종류가 있으며, 이 중 스프링와셔는 충격이나 반복적인 외력이 높은 체결력을 필요로 하는 자동차, 항공기, 산업기계 등 다양한 분야에서 사용되고 있다. 스프링와셔는 연강선재를 사다리꼴 단면으로 인발, 코일링, 절단 후 열처리를 하여 제조하는데, 열처리 후 파단되는 문제가 있다. 본 연구는 열처리 후 파단되는 문제를 해결하고자 열처리를 생략하고 기존 제품과 동일한 경도 및 성능이 유지되도록 소재 변경과 인발금형에 초경롤러를 적용하였으며, 유한요소해석 프로그램인 DEFORM-3D와 ANSYS를 이용하여 냉간 인발 시뮬레이션을 실험 결과와 비교 및 분석하여 현장에서 사용할 수 있는 설계표준을 제시하였다. A washer is a mechanical element mounted between a bolt and nut to reduce the contact pressure between fasteners and preventing loosening. Spring washers are used to maintain high clamping forces against impact or repetitive external forces in automobiles, aircraft, and industrial machinery. Spring washers are generally manufactured by heat treatment after drawing, coiling, and cutting; however, there is a problem of increased fracture properties after heat treatment. In this study, to solve this post-heat-treatment problem, the material was changed to a high-strength span wire with a simplified manufacturing process using a carbide roller. The roller and spring washer were designed by Creo and simulated using finite element modeling code DEFORM-3D and ANSYS. The simulated results were analyzed and compared with the experimental results to suggest a design standard.
高冷地農業에 의한 有明山 周邊의 植生破壞 現況 및 對策
安永熙,曺海鏞 한국환경정책학회 1996 環境政策 Vol.4 No.2
This paper searched the present situation of flora destructions by which growing in highland were caused in Mt. Daeboo and around Mt. Yumyoung. Around the crest of Mt. Daeboo and M't. Yumyoung located on the central districts in korea, plentiful temperate vegetations have been inhabited about 800 meters aye sea level, Especialii, this area includes the habitat of Rodgersia podophylla Viola webstreri and Saussurea, seoulensis legal pretected plants, which are Korean rare and endangered plants. Recently, extensive vegetable culture in highland of this area have devastated important vascular plants, The result of analysis suggests that agiculture in highland based on ecological evaluation are needed to minimize the appearance of man-induced vegetation degration.