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김경률(Kyung-Ryool Kim),김영석(Young-Suk Kim),안대철(Dae-Cheol Ahn) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-
본 논문에서는 환형 부품의 다중형상 링 롤링 제조공정 개발에 관한 연구이다. 링 롤링 공법의 여러 가지 장점 중 특히, 재료의 회수율을 극대화시키기 위한 다중의 형상의 링 롤링 제조 공정을 제안하였 다. 또한 유한요소해석과 시험 제작한 결과를 토대로 공정 체적화와 제품의 품질을 검증하였다.
외경이 큰 환형 부품의 다중형상 열간 링 롤링 공정의 개발
김경률(Kim, Kyung-Ryool),김영석(Kim, Young-Suk) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.2
열간 링 롤링 공법은 열간단조 후의 잠열을 이용하기 때문에 가공 부하가 적고 최종 환형제품에 가까운 제품을 제조하는 장점이 있다. 본 연구에서는 열간 링 롤링 공법에 의한 대형 직경의 환형 부품의 다중형상 링 제조를 목표로 AFDEX2D 및 AFDEX3D/HEXA/RING 시뮬레이터(simulator)를 이용하여 열간 단조공정부터 링 롤링 공정까지 연계된 공 정을 유한요소 해석하였다. 또한 링 롤링공정의 유한요소해석 시간을 줄이기 위해 소성변형이 일어나고 있는 영역에서만 요소망을 조밀하게 재구성하는 이중요소 시스템을 적용하였다. 이 유한요소해석 결과를 바탕으로 실제 공정을 설계하고 실 험하여 개발된 제품이 품질 규격을 만족하는지를 확인하였다. 또한 링 롤링 실험 완성품을 통하여 부품의 품질수준 및 공정 능력을 평가하였다. 그 결과, 개발된 환형 부품은 40%의 투입재료 감소과 최종 제품의 원소재 회수율이 24% 증가하였다. 또한 링 롤링 제품은 내, 외경의 진원도가 0.5mm로 우수하였으며 공정능력 분석결과 외경 Cpk 1.49, 내경 Cpk 0.85를 확보하여 환형 부품의 다중 형상 열간 링 롤링 공정의 최적화를 실현하였다. In this study, multilayered rings with a large outer diameter have been developed using a hot ring rolling process. The ring rolling process has been analyzed by rigid plastic finite element analyses (FEA) using the AFDEX2D and AFDEX3D/HEXA/RING simulators, where the finite element meshes received severe plastic deformation are remeshed into a fine mesh-size using a dual-mesh system. According to the simulated results, the design variables of the multilayered rings were determined and real tests were conducted to check the validity of the simulation results. By adopting the hot ring rolling process, the input weight of raw materials was reduced by 40% against the conventional hot forging process and that the recovery rate was increased by 24%. The measurement of the averaged roundness was satisfied within 0.5 mm for both the inner and outer diameters. Moreover, the hot ring rolling processes yielded 1.49 Cpk for the outer-diameter and 0.84 Cpk 0.84 for the inner-diameter.
초소형 전기차용 3단 변속기 가속수명평가 방법에 관한 연구
최승민(Seung Min Choi),김진복(Jin Bok Kim),김형준(Hyung Joon Kim),이정일(Jeong Il Lee),김경률(Kyung Ryool Kim),정훈(Hoon Jeong) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
In this study, the accelerated life test method was designed by extracting parameters from a transmission for a micro-electric vehicle with a motor of less than 15 Kw and calculating a shortened accelerated life test time based on the linear cumulative damage theory. Major parameters were selected to develop an accelerated life test method, and accelerated test time calculation and test pattern were presented. As a result of calculation using the shape parameter values, a test with a failure-free test time of 1,506 hours is required to guarantee a service life of 60,000 km (equivalent to 3 years) on a passing basis of 90% confidence level. Based on the maximum design torque that can be output at each stage, taking into account the cumulative damage effect. If the accelerated test is performed at 132%, the accelerated index is calculated as 23.4, reducing the time for the fault-free accelerated life test to 64.3 hours. The pattern was set so that the fatigue durability test of 64.3 hours for each stage of reversing and advancing the no-failure accelerated life test time was performed. However, since the forward first stage and the backward stage are composed of the same power transmission logic, the test time was divided. The test was designed to perform a total of 193 hours.
초소형 전기차용 3단 변속기 가속수명평가 방법에 관한 연구
최승민(Seung Min Choi),김진복(Jin Bok Kim),김형준(Hyung Joon Kim),이정일(Jeong Il Lee),김경률(Kyung Ryool Kim),정훈(Hoon Jeong) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.11
In this study, the accelerated life test method was designed by extracting parameters from a transmission for a micro-electric vehicle with a motor of less than 15 Kw and calculating a shortened accelerated life test time based on the linear cumulative damage theory. Major parameters were selected to develop an accelerated life test method, and accelerated test time calculation and test pattern were presented. As a result of calculation using the shape parameter values, a test with a failure-free test time of 1,506 hours is required to guarantee a service life of 60,000 km (equivalent to 3 years) on a passing basis of 90% confidence level. Based on the maximum design torque that can be output at each stage, taking into account the cumulative damage effect. If the accelerated test is performed at 132%, the accelerated index is calculated as 23.4, reducing the time for the fault-free accelerated life test to 64.3 hours. The pattern was set so that the fatigue durability test of 64.3 hours for each stage of reversing and advancing the no-failure accelerated life test time was performed. However, since the forward first stage and the backward stage are composed of the same power transmission logic, the test time was divided. The test was designed to perform a total of 193 hours.
픽업 유틸리티 전기차용 듀얼 모터 EVT의 가속수명평가에 관한 연구
최승민(Seung Min Choi),이정일(Jeong Il Lee),김형준(Hyung Joon Kim),이수정(Su Jeong Lee),김경률(Kyung Ryool Kim),정훈(Hoon Jeong) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11
In this study, an accelerated life test method based on the linear cumulative damage theory was designed to ensure the reliability of the dual motor EVT for a 500kg utility electric vehicle. In order to develop an accelerated life test method, major parameters were selected, and accelerated life calculation and test patterns were presented. As a result of calculation using the shape parameter values, a test with a fault-free time of 3,765 hours is required to ensure the service life of 150,000 km(equivalent to 7 years) based on 90% confidence level acceptance criteria. Considering the cumulative damage effect, the maximum design torque that can be output at each stage was used as a reference. When performed at 132 percent of the maximum design torque, the acceleration index is calculated as 23.4 and the acceleration life test time is shortened to 161 hours. For the accelerated life test, the pattern was set to perform a constant-speed durability test of 80.5 hours each reverse and forward. As a result of the test, no physical abnormality was found, and the efficiency was 96% before and after the test. Accordingly, it is judged that the reliability of the durability capability of EVT has been secured.