공구유닛 구동기어의 치형 최적설계에 관한 연구

류성기(Sungki Lyu),김동선(Dongseon Kim),백권인(Gwon-In Baek),진진(Zhen Qin) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11

질소이온코팅 SCM415강의 마찰ㆍ마모특성에 관한 연구

류성기(Sungki Lyu),하휘파(HuiBo He),이상현(Sanghyun Lee),이동규(Donggyu Lee),손유선(Yusun Son) 한국생산제조학회 2006 한국공작기계학회 춘계학술대회논문집 Vol.2006 No.-

SCM415 alloy was implanted with nitrogen ions using plasma source ion implantation(PSII), at a dose range of 1×10 to 6×10¹?N?㎝?². Auger electron spectrometry(AES) was used to investigate the depth profile of the implanted layer. Friction and wear tests were carried out on a block-on-ring wear tester. Scanning electron microscopy(SEM) was used to observe the micro-morphology of the worn surface. The results revealed that after being implanted with nitrogen ions, the frictional coefficient of the surface layer decreased, and the wear resistance increased with the nitrogen dose. The tribological mechanism was mainly adhesive, and the adhesive wear tended to become weaker oxidative wear with the increase in the nitrogen dose. The effects were mainly attributed to the formation of a hard nitride precipitate and a supersaturated solid solution of nitrogen in the surface layer.

The Study on the Analytical Prediction of Bearing Life and Load Distribution for Plugin HEV

Qi Zhang(장기),Zhezhu Xu(허철수),Sungki Lyu(류성기) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.5

The transportation is almost dependent on a single fuel petroleum with transportation energy dilemma. Hybrid Electric Vehicle(HEV) technology holds more advantages on efficiency improvements for petroleum consumption at the transportation. And bearing is recognized as the important component of gearbox. Gearboxes for HEV transmission have been ensured the highest reliability over some years in withstanding high dynamic loads. At the same time, the demands of lilghweight design and cost minimization are required by thought-out design, high-quality material, superior production quality and maintenance. In order to design a reliable and lightweight gearbox, it is necessary to analyze bearing rating life methods between standard and different bearing companies with calculation methods for modification factors. In this paper, the influence of life time of bearings will be pointed out. Bearing contact stress and load stress distribution of HEV gearbox are obtained and compared with Romaxdesigner and BearinX. And the unequal wear of the left bearing for the gearbox internediate shaft is investigated between simulation and test.

The Calculation and Experiment for Measurements over Pins of the External Helical Gears with an Odd Number of Teeth

Zhang, Qi,Kang, Jaihwa,Li, Qing,Lyu, SungKi 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.12

For the calculation and measurement between pins in the external helical gears with an odd number of teeth, they have been studied for many years. And the calculation methods and measurements are also described in DIN and AGMA standards. However, for ISO standard, a clear conclusion has not been given yet. The differences between the research results and standards are still inconsistent in some cases of the actual situation. In the actual measurements, the pin instead of the ball is always used by survey crew. It is unreasonable that an incorrect value (usually the value across the ball) and measuring methods are used. In this paper, different calculations and measuring methods of different standards are firstly expressed. For different measurement tools, like dial caliper, outside micrometer and disc micrometer, the measurement results are not the same. Therefore, two test gears were manufactured and analyzed to verify the accuracy and reliability of the measurement methods between software calculation and manual measurement over pins. It is found that the calculation and measurement methods of DIN, AGMA or similar methods are feasible and reliable, but for the measuring surface of the measuring tools, the pin should be in a steady state along the spiral groove. Reliable measurement values are obtained to ensure the accuracy of the measurement. It is helpful to understand the measurements of the standard or similar methods through theoretical analysis and experiments.

Design and Structural Stability Investigation of Novel Flat-Face Multi-coupling Systems for Hydraulic Power Equipment

Zhen Qin,Xiaoran Tang,Yu-Ting Wu,Sungki Lyu,Sang-Hu Park 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.10

Hydraulic power transmission systems have been widely used in recent years by virtue of their precise transmission, large driving force, safety, and reliability. Designs of hydraulic systems are being proposed that provide more convenient installation, greater driving force, and are more environmentally friendly. With this evolution, traditional hydraulic couplings are gradually becoming unable to meet the ever-changing hydraulic circuit connection requirements. In this paper, based on the fluid-structure interaction numerical investigation method and experimental verification methods, the construction safety and stability of the novel flat-face coupling system (NFFCS) is investigated, and the safety level of its construction stability is compared with that of a conventional flat-face coupling system. In addition, the mechanism design for 4-circuit and 6-circuit hydraulic quick coupling equipment based on the NFFCS technology is proposed, and the kinematic principles of its rapid and safe connection are explained. A series of structural stability simulations are implemented and the safety and reliability are discussed.

유압 구동시스템용 체크 밸브의 유동특성 및 구조안정성에 관한 연구

우위팅(Yu-Ting Wu),진진(Zhen Qin),곽기명(Gimyeong Gwak),류성기(Sungki Lyu),조용민(Yongmin Cho),백승호(Seoungho Back),박상후(Sanghu Park) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.7

유압 구동시스템은 여러 산업기계에서 널리 사용되며 체크 밸브는 유압 동력전달시스템의 중요한 부품이다. 하지만 유로와 하우징의 부적절한 설계로 인하여 고압의 오일이 전달될 때 체크 밸브의 누유 및 손상과 같은 문제가 빈번하게 나타난다. 이러한 문제를 해결하기 위하여 본 연구에서는 유한체적법(FVM)과 유체 동역학 기반의 수치적 연구 수단을 활용하여 유압 기계에 사용하는 “L”자형 고압 체크밸브를 바탕으로 설계를 평가하였다. 또한 유한요소법(FEM)을 바탕으로 내부 고압을 고려하여 체크 밸브 하우징의 구조적 안정성에 대해 시뮬레이션을 진행하였다. 본 논문에서 사용한 연구방법은 다양한 유압시스템용 체크 밸브에 적용이 가능하며 유압 동력전달 과정의 안전성을 보장하기 위하여 중요한 설계 평가 사례를 보였다. Hydraulic drive systems are widely used in the equipment used in various industries, such as agriculture and construction. The internal check valve is an important part of the hydraulic power transmission system in a hydraulic machinery. Because of improper design of the flow circuit and housing, check valves are exposed to various problems, such as leakage and damage, frequently during high pressure transmission. To solve this problem, the L-shaped high-pressure check valve used in hydraulic machinery was designed and evaluated using the finite volume method and numerical research method based on fluid dynamics. Furthermore, considering the impact of high internal pressure on the check valve shell, the structural stability of the valve was simulated using the finite element method. The research method adopted in this study can be applied to check valves in various hydraulic systems. Additionally, an important design and evaluation example is provided to ensure the safety of the hydraulic power transmission process.

Characteristic Evaluation of Friction and Wear in the C-N and TiN Coated Gear

Lu, Long,Xu, Feng,Jiang, Tao,Zhang, Qi,Lyu, Sungki 한국정밀공학회 2010 International Journal of Precision Engineering and Vol.11 No.1

C-N films were deposited on the 20CrMo alloy steel substrate by the Plasma Source Ion Implantation (PSII) method and TiN films were coated on the same material by the Physical Vapor Deposition (PVD) method. It was found that friction coefficient of C-N coating were relatively lower than TiN coating. And with the load increased, the friction coefficients of C-N coating and TiN coating were both decreased. Then the author puts forward the test rig, working under the conditions of 1,800 rpm, $20\;N{\cdot}m$ for 100 h. The observations by microscope showed the wear reduced. The antiwearing performance enhanced prominently. But the TiN coated gear had a more serious friction phenomenon than C-N coated gear. This is caused by that coating of TiN, which was made at a high temperature about $500^{\circ}C$. The high temperature led to the substrate intenerated and the surface hardness had decreased from 850 HV to 630 HV. PSII method eliminates the tempering problem of the coating of C-N films, which had better wear resistance than TiN films. The friction and wear resistance of gears which coated by C-N films ameliorated significantly.

Experimental Application of Pitting Formation for 20MnCr5 Carburized Gear Tooth

Zhang, Jing,Zhang, Qi,Wu, Changhong,Xu, Zhezhu,Lyu, SungKi 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.5

Gear tooth contact analysis and a FZG gear test rig were applied to study and analyze gear contact fatigue in this paper. Under the range of operating conditions, experiments were performed in the test rig by using standard FZG type C spur gear test specimens which were made from 20MnCr5 gear steel. Test rig, spur gear test specimens, the properties of the gear material were also introduced. After the test, pitting formation was investigated using scanning electron microscopy. Two kinds of fatigue spallings caused by subsurface fatigue failure and surface fatigue failure were investigated. And energy spectral analysis for two kinds of fatigue positions were analyzed by the EDS detector, the materials of subsurface fatigue failure are the oxide $Al_2O_3$ and the carbide, and the black textures of surface fatigue failure are the oxide and the non-martensitic material. Through the mechanism analysis of this gear contact fatigue failure, it is founded that reducing the oxygen content in the material, can effectively reduce the oxide inclusions in the steel. It would provide a reliable reference study for 20MnCr5 carburized gear.

400 N급 사이드 스러스터 설계 및 시험검증

김형민(Hyeong-Min Kim),정회택(Hoe-Taek Jung),진진(Zhen Qin),류성기(Sungki Lyu) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

노벨 정량 분말 공급 장치의 설계 및 연구

우위팅(Yu-Ting Wu),진진(Zhen Qin),이윤승(Yunseung Lee),류성기(Sungki Lyu),백승호(Seoungho Back),박상후(Sanghu Park) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.8

분말을 친환경적이고 정량적으로 공급하기 위하여 본 논문에서는 노벨 분말 공급 장치의 설계를 제안하고 그 메커니즘 설계 원리에 대해 분석한다. 장치내 분말의 유동 특성을 관찰하기 위하여 분유를 연구 대상으로 선정하였다. 분말 입자 사이의 공극률과 충돌효과를 고려하여 유동영역 내에서 고밀도의 입자 유동 모델을 구축하였으며 Fluent를 활용하여 순간적인 CFD 시뮬레이션을 수행하였다. 무거운 하중을 받는 장치의 구조적 안전성을 고려하여 일련의 유한요소법 기반 구조 강도의 시뮬레이션을 실시하고 메커니즘의 신뢰성을 검증하였다. 또한 3D 프린터를 활용하여 분말 공급 장치의 시제품을 제작하였으며 섭취량 실험을 수행하였다. 결론적으로 제안된 분말 공급 장치는 내부 유동 특성, 구조적 안전성, 실제 분말 공급의 정량 정밀성 등 측면에서 만족스럽다고 평가할 수 있다. 본 연구에서 사용된 설계 및 검증 방법과 다양한 메커니즘의 설계를 위한 유용한 이론을 제시하였다. To precisely feed powders or particles in an environmentally friendly manner, a novel apparatus for powder feeding is proposed. The kinematics and design principles of the mechanism were analyzed. To observe the flow characteristics of the powder in the apparatus, milk powder was selected as the study object. By considering the voidage and collision effect between particles, the dense discrete phase method–discrete element method collision model was established and investigated based on the commercial computational fluid dynamics software ANSYS Fluent. To observe the structural stability of the proposed apparatus under an extreme load condition, a series of finite-element-method-based structural simulations were implemented and the reliability of the design was verified. A prototype was made based on three-dimensional printing technology, and the feeding precision was compared with that of the traditional measuring spoon. The design was satisfactory in terms of flow characteristics, structural safety, and quantitative feeding. The design and investigation methods used in this study can provide an important theoretical reference for the design of a variety of apparatus.