Load Distribution Analysis for Industrial Reducer Considering Axis of Gear

( Seung-je Cho ),( Young-jun Park ),( Woo-jin Chung ),( Kyu-jeong Choi ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

The reducer is a device that amplifies the force by lowering the speed of the input part when the load of the operating part is large. In order to optimize the design of the reducer, it is important to make the reducer gear lighter and smaller. For this purpose, it is necessary to accurately predict and analyze the distribution of the load acting on the gear. However, the existing research about analysis of the load distribution of gears was mostly based on only gears. This is problem because misalignment of gears is not properly reflected in the analysis. The misalignment is a phenomenon in which gears cannot be properly engaged due to external and complex influences of components such as shafts, bearings, and housings other than gears. This causes a reduction in the life of gears and noise, the damage of the teeth is also. Because of this problem, it is very important to perform the load distribution analysis considering the influence of misalignment in the optimum design of the reducer. Therefore, in this study, I analyzed how the load distribution of the gears is by taking into account not only the gears but also the axes of the gears. The gears and axes are modeled and the meshes are divided appropriately so that detailed analysis is carried out and the distribution of the maximum load applied to the gears is analyzed by setting analytical boundary conditions for static conditions. As a result of the analysis, I could see the unbalance of the load due to the misalignment of the gear, and conclude the analysis considering the gear axis as well as the gear is meaningful. It can be seen from this point of view that a systematic approach such as gear shafts, bearings, and housings, rather than the sides of the components, is essential for accurately analyzing load bias due to misalignment of gears.

기계유압식 무단변속기용 기어류의 강도해석에 관한 연구

배명호(Myung Ho Bae),배태열(Tae Yeol Bae) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11

The power train of hydro-mechanical continuously variable transmission for forklift makes use of hydro-static unit, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The complex helical & planetary gears are very important parts of the transmission for forklift because of a strength problem. In the present study, calculating specifications of the complex helical & planetary gear train and analyzing the gear bending and compressive stresses of the gears. It is necessary to analyze gear bending and compressive stresses confidently for optimal design of the complex helical & planetary gears in respect of cost and reliability. In the paper, analyze actual gear bending and compressive stresses of complex helical & planetary gears using Lewes & Hertz equation, also verify the calculated specifications of the complex helical & planetary gears by evaluating the results with the data of allowable bending and compressive stress from the Stress - No. of cycles curves of gears. In addition, in this paper also analyze actual gear scoring and evaluate the possibility of scoring failure of complex helical & planetary gear train of hydro-mechanical continuously variable transmission for forklift.

The effect of gear-manufacturing quality on the mechanical and thermal responses of a polymer-gear pair

Zorko Damijan,Wei Peitang,Vukašinović Nikola 한국CDE학회 2024 Journal of computational design and engineering Vol.11 No.1

Gear-manufacturing quality affects the load sharing between the meshing gears as well as the load distribution along the width of the tooth. This study aims to investigate the effect of gear-manufacturing quality on the mechanical and thermal states of polymer-gear pairs and consequently on their lifetime. The deviations of the geometric quality parameters, i.e., the lead profile and pitch, were found to have a substantial effect on the stress (root and flank) state of the gear. The effect of the lead deviation was found to be most pronounced for the quality grades Q12 to Q10, where depending on the load, a 30–80% stress reduction was observed when improving the gear quality from Q12 to Q10. Improving the quality from Q10 to Q8 did not lead to a substantial improvement in the load distribution and the observed stress reduction was in range of 5–20%. Similar trends were found for the pitch deviation, where again the most pronounced stress reduction was seen when improving the quality grade from Q12 to Q10. The study reveals where the most effective changes, leading to an increased gear-life, can be achieved. Improving the gear quality grade from Q12 to Q11 proved to have a much more substantial effect than improving the gear quality from Q9 to Q8. Considering that improving the gear quality from Q12 to Q11 or even Q10 can be achieved by a proper tool design and corrective iterations with the right process parameters, while improving the quality from Q9 to Q8 is by far more challenging. A novel methodology is proposed to assess the effect of the gear’s quality on the generation of heat and the resulting operational temperature. The proposed methodology enables more accurate prediction of the gear pair’s operating temperature.

고감속비를 가지는 베어링일체형 구조의 2단 전위 감속기의 개발

황일규(Il-Kyu Hwang),최정수(Jung-Soo Choi),정문수(Moon-Soo Jung) (사)한국CDE학회 2012 한국CDE학회 논문집 Vol.17 No.5

Planetary gearing is a gear system consisting of one or more planet gears, revolving about a sun gear. While the planetary gear system has many advantages- for example, high power density, large reduction in a small volume, multiple kinematic combinations, pure torsional reactions, and coaxial shafting, it has not been widely used because of its high bearing loads, inaccessibility, and design complexity. It is also necessary to shift several pairs of gear profiles at a same time. Therefore, designing profile shifted planetary gear system is a difficult and know-how dependent job. This study provides a practical solution to design a profile shifted gear system by the procedural design scheme, and proposes a bearing integrated structure of the dual stage profile shifted gear system with a robust output end. A dual stage profile shifted gear system with the bearing integrated structure is manufactured by the proposed design scheme in this study. This gear system is verified that it is good enough to commercialize, because it has high performance with high gear ratio and robust output end against axial and radial directional runouts in a small space.

Dynamic characteristics of a planetary gear system based on contact status of the tooth surface

Ruibo Chen,Jianxing Zhou,Wenlei Sun 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.1

Studies on the planetary gear have attracted considerable attention because of its advantages, such as compactness, large torque-toweight ratio, vibrations, and high efficiency, which have resulted in its wide applications in industry, wind turbine, national defense, and aerospace fields. We have established a novel dynamic model of the planetary gear transmission by using Newton’s theory, in which some key factors such as time-variant meshing stiffness, phase relationships, and tooth contact characteristics are considered. The influences of gear axial tipping, operating conditions, and the meshing phase on the contact characteristics and the dynamic characteristics were researched systematically. It was found that the contact area of the tooth surface was moved due to the axial gear tipping, which obviously affected the meshing stiffness. With the increase in the inclination angle of the sun gear, the meshing stiffness decreases, which produces an evident influence on the high natural frequency in the planetary transmission system. In terms of the dynamic characteristics of the system, the component of rotating frequency appeared in the dynamic meshing force of the sun gear and the planetary gear. Moreover, the floating track of the center wheel varied significantly and exhibited an oval distribution as the inclination angle of the sun gear changed. When the inclination angle of the sun gear increased, the rotating frequency component increased significantly, but the other meshing frequency components remained unchanged; meanwhile, the deformation of the floating track also increased. If the inclination angle of the sun gear changes, the vibration state of the system and the collision impact could become more serious, and the lifetime of the planetary transmission system will reduce. Furthermore, when the load was increased, we found that the gear-tooth contact zone transformed from line contact to surface contact, the meshing stiffness increased, the effect of high natural frequency on the planetary transmission system became more evident, but its low-order natural frequency remained stable. With regard to the dynamic characteristics of the system, the components of the major frequency at the external gearing remained unchanged, but the rotation frequency of the sun gear and the meshing frequency amplitude increased linearly with the increase in load. In conclusion, the variation in the meshing stiffness of the planetary gear system had minor impact on the low-order natural frequency, but had a significant impact on the high natural frequency of the planetary transmission system due to the phase variation of the gear.

Applying Fishing-gear Simulation Software to Better Estimate Fished Space as Fishing Effort

이지훈,이춘우,최무열,이군호 한국수산과학회 2011 Fisheries and Aquatic Sciences Vol.14 No.2

Modeling fishing-gear systems is essential to better understand the factors affecting their movement and for devising strategies to control movement. In this study, we present a generalized mathematical modeling methodology to analyze fishing gear and its various components. Fishing gear can be divided into a finite number of elements that are connected with flexible lines. We use an algorithm to develop a numerical method that calculates precisely the shape and movement of the gear. Fishing-gear mathematical models have been used to develop software tools that can design and simulate dynamic movement of novel fishing-gear systems. The tool allowed us to predict the shape and motion of the gear based on changes in operation and gear design parameters. Furthermore, the tool accurately calculated the swept volume of towed gear and the surrounding volume of purse-seine gear. We analyzed the fished volume for trawl and purse-seine gear and proposed a new definition of fishing effort, incorporating the concept of fished space. This method may be useful for quantitative fishery research, which requires a good understanding of the selectivity and efficiency of fishing gear used in surveys.

Study on Empirical Gear Profile Micro-modifications for Gear Transmission

Qi Zhang(장기),Jiu-Gen Wang(왕주겐),Sung-Ki Lyu(류성기) 한국기계가공학회 2017 한국기계가공학회지 Vol.16 No.3

When gears mesh, shock and noise are produced as results of tooth error and tooth deformation under load. Transmission error (TE) is the most important cause of gear noise and vibration because TEs affect the changes of the force and the speed of gears. Gear tooth modification research plays a positive role in reducing TE and improving the design level and transmission performance of transmission systems. In high-precision manufacturing gear, gear tooth modification is also commonly used to reduce noise in practical applications. In order to study the accuracy of gear transmission, some empirical gear profile micro-modifications are introduced, and a helical gear pair is modeled and analyzed in RomaxDesigner software to investigate the utility of these modification methods. Some of these will be selected as experimental proposals for gear pairs, and these manufactured gears will be tested and compared in a semi-anechoic room later. The final purpose of this study is to find reasonable and convenient empirical formulae to facilitate improved gear production.

백래시와 치형 수정, 크라우닝을 고려한 인벌류트 스퍼 기어 모델링 시스템 개발

이강수(Kang-Soo Lee) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.8

이 연구에서는 스퍼 기어의 치형이 생성되는 이론을 정리하고, 이를 이용해 산업계에서 실제 사용되는 스퍼 기어 자동 모델링 시스템을 개발하였다. 기어 치형은 크게 이끝원, 이뿌리원, 필렛 곡선, 인벌류트 곡선 등 네 개의 곡선으로 이루어진다. 이 연구는 이러한 네 개의 곡선 생성에 대한 이론적인 근거를 제시하고, 이론적인 치형에서 백래시, 치형 수정, 크라우닝 등이 있는 실제로 사용되는 치형에 대한 이론 전개를 한 후 치형을 모델링하는 시스템을 구현하였다. 기존에는 기어 치형 전체를 체계적으로 생성하기 위한 이론 정리가 잘 되어 있지 않고, 특히, 백래시, 인벌류트 치형 수정, 크라우닝을 반영하는 치형 모델링에 대한 연구가 없어 실제 사용되는 기어를 정확하게 모델링하기 어려웠다. 이 연구로 가장 형상이 까다로운 기계 요소인 기어에 대한 모델링 기술이 발전할 것으로 기대한다. 또한, 이 연구는 스퍼 기어 뿐 아니라 헬리컬 기어, 베벨 기어, 스파이럴 베벨 기어의 실질적인 치형을 생성하는 연구에 대한 기초가 될 것으로 기대한다. Based on the theory of generating the practical tooth profile of spur gears, I implemented a spur gear modeling system. Gear teeth are composed of four curves: tip circle, root circle, fillet curve, and involute curve. This paper presents the theoretical basis for the generation of these four curves. Based on the knowledge of the actual gear profile with backlash, profile modification, and crowning, I implemented a modeling system of practical spur gears. The generation of a whole tooth profile has not been well organized in the earlier studies. In particular, a lack of study on gear modeling that reflects backlash, profile modification, and crowning makes it difficult to accurately model the gears that are actually used in the industry field. This study is expected to enhance the modeling technology for gears that have the most difficult shape among mechanical elements. In addition, this study is expected to serve as the basis for the study of modeling a practical tooth profile of spur gears, helical gears, bevel gears, and spiral bevel gears.

Analytical Study on Improvement in Load Sharing for Planetary Gear Set using Floating Ring Gear

Chung, Woo-Jin,Choi, Kyujeong,Oh, Jooseon,Park, Young-Jun,Lee, Ki-Hun Korean Society for Agricultural Machinery 2018 바이오시스템공학 Vol.43 No.4

Purpose: The load on the planet gear of a planetary gear set is uniformly distributed. However, manufacturing and assembly errors cause uneven load sharing in the planetary gear set. To solve this problem, most studies have suggested applying a floating sun gear to the planetary gear set. However, the effect of the floating ring gear and floating carrier has not been extensively studied. This study aimed to investigate the effect of the floating ring gear. Methods: Two models were developed; one was the fixed ring gear model, and the other was the floating ring gear model. In the fixed ring gear model, the clearance between the ring gear and the housing was $0{\mu}m$, and in the floating ring gear model, the clearance was from $10{\mu}m$ to $100{\mu}m$. The load sharing of the planetary gear set was evaluated by the load sharing factor. Results: Our study showed that with increase in clearance, the load sharing factor of the planetary gear set approached unity. In addition, when the clearance increased above a certain level by which a fully floating ring gear was achieved, the load sharing factor was not affected by the clearance. Conclusions: This indicates that the fully floating ring gear increased the power density of the planetary gearbox by uniformly dividing the load of the planetary gear set. For this reason, the size of the gearbox could be decreased by using a fully floating ring gear.

Analytical Study on Improvement in Load Sharing for Planetary Gear Set using Floating Ring Gear

정우진,최규정,오주선,박영준,이기헌 한국농업기계학회 2018 바이오시스템공학 Vol.43 No.4

Purpose: The load on the planet gear of a planetary gear set is uniformly distributed. However, manufacturing and assembly errors cause uneven load sharing in the planetary gear set. To solve this problem, most studies have suggested applying a floating sun gear to the planetary gear set. However, the effect of the floating ring gear and floating carrier has not been extensively studied. This study aimed to investigate the effect of the floating ring gear. Methods: Two models were developed; one was the fixed ring gear model, and the other was the floating ring gear model. In the fixed ring gear model, the clearance between the ring gear and the housing was 0 μm, and in the floating ring gear model, the clearance was from 10 μm to 100 μm. The load sharing of the planetary gear set was evaluated by the load sharing factor. Results: Our study showed that with increase in clearance, the load sharing factor of the planetary gear set approached unity. In addition, when the clearance increased above a certain level by which a fully floating ring gear was achieved, the load sharing factor was not affected by the clearance. Conclusions: This indicates that the fully floating ring gear increased the power density of the planetary gearbox by uniformly dividing the load of the planetary gear set. For this reason, the size of the gearbox could be decreased by using a fully floating ring gear.