gear wheel
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2022 ◽  
pp. 1-10
Author(s):  
Gaurav Nagalia

Abstract This article presents the mechanisms of polymer wear and quantifies wear in terms of wear rate (rate of removal of the material). Interfacial and bulk wear are discussed as well as a discussion on the wear study of "elastomers," "thermosets," "glassy thermoplastics," and "semicrystalline thermoplastics." The article also discusses the effects of environment and lubricant on the wear failures of polymers. It presents a case study on considering nylon as a tribological material and failure examples, explaining wear resistance of polyurethane elastomeric coatings and failure of an acetal gear wheel.


2021 ◽  
Vol 6 ◽  
Author(s):  
Ngoc-Huy Tran ◽  
Chin-Fei Huang ◽  
Jeng-Fung Hung

The purpose of this study is to explore the effectiveness of a STEAM (Science, Technology, Engineering, Arts, Mathematics) -based curriculum on junior high school students’ scientific creativity. The main topic of the STEAM-based curriculum in this study is an ancient mechanical clock that was designed and produced by the authors’ team. Further, the main concept of the ancient mechanical clock is about a gear wheel. Hence, this study designed two stages of courses which were gear wheel science courses (2 weeks) and STEAM-based courses (2 weeks). A total of 62 junior high school students from two different courses participated in this study and were divided into a control group and an experimental group. This study adopted a counterbalance design. The control group joined gear wheel science courses first and joined STEAM-based courses second. In contrast, the experimental group joined STEAM-based courses first. Both groups were asked to complete a pre-test, a middle-test, and a post-test by completing the “Scientific Creativity Test (Cronbach’s α 0.87)”. The results from paired t-test analyses showed that control group students did not show significant differences in scientific creativity before and after joining the gear wheel science courses, but they got significantly higher scores after joining STEAM-based courses than before. On the other hand, the experimental group students got higher scores in scientific creativity after joining STEAM-based courses than before, and persisted in getting higher scores after joining the gear wheel courses than before. Furthermore, the results implied that the STEAM-based courses might help students maintain or continue their scientific creativity. Further discussion is provided.


2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Tamer Tevetoglu ◽  
Mark Henss ◽  
Yvonne Gretzinger ◽  
Bernd Bertsche

One failure mechanism of gear wheels is pitting. If the gear wheel is case hardened, pitting degradation dominates normally at one tooth only. All the other teeth are still intact at the standardized end of life criterion of 4 % pitting area based on the total tooth area. Using an operational strategy that was developed at the Institute of Machine Components, the service life of gear wheels can be extended by a local stress reduction at the weakest tooth. This is accomplished by applying an adapted torque at the transmission input that shifts a minimum torque in the area of the pre-damaged, and thus, weakest tooth. Consequently, all remaining teeth with higher load bearing capacity are subjected to higher torque. Prerequisite for the described theoretical operational strategy is knowledge on pitting-size and -position. The detection of these properties in operation is not state of the art yet. In this work, only the gearbox vibration signal is known without explicit knowledge about the inside pitting. So the challenge is to determine the health for each individual tooth and to choose an optimal adapted torque based on this. This is especially difficult due to differing growth rates of pittings on one individual gear wheel. Hence, different pittings dominate over the service life, which results in the need of a continuous optimization of the torque control. Algorithms of Reinforcement Learning (RL) are particularly suitable for this challenge. In this branch of Machine Learning (ML), an agent interacts inside an environment and learns by getting rewards for taking actions at given states. In this study, the environment is a gearbox-simulation-model, the state is the current vibration signal, and the action is the chosen adapted torque. Thus, it is possible to let the algorithm learn the whole operational strategy, from online failure detection to an adapted torque at the transmission input. The results of this study show the theoretical feasibility of the operational strategy using Double Deep Q Networks as the RL Algorithm. The algorithm is able to learn a suitable reaction to pittings that increase linearly or progressively at an early stage and therefore delays their growth within the defined limits. Thus, the lifetime of the gearbox is extended while maintaining the same total power of the gearbox. As an outlook, the results will be examined for their sensitivity on several influencing factors in a further study. The wider view is to use this simulation on a test rig and validate the results.


2021 ◽  
Vol 1199 (1) ◽  
pp. 012019
Author(s):  
S Sivák ◽  
S Maláková

Abstract The development of modern machines and means of production is characterized by ever-increasing performance parameters with decreasing equipment weight. When designing large gears, it is also necessary to consider the influence of the body shape of the gear wheel. The body shape of gear wheel must meet the basic requirements of stiffness and strength with the lightest possible construction of the gear wheel body. The work is focused on large gears, made with relief. Such gears can be forged, cast, or made by welding. The shape of the gear wheel body depends on several factors such as the size of the wheel, the material, the method of manufacture or use. The paper provides an overview of the body shapes used by large spur gears. These body shapes of spur gears will be the subject of further research, where suitability will be assessed based on stiffness of teeth and wheel weight.


2021 ◽  
Vol 9 (10) ◽  
pp. 1060
Author(s):  
Silvia Maláková ◽  
Michal Puškár ◽  
Peter Frankovský ◽  
Samuel Sivák ◽  
Daniela Harachová

The basic properties of gears must be considered: the shape of their gearing, their load capacity, and the meshing stiffness, which affects the noise and vibration. When designing large gears, it is important to choose the correct shape of the gear body. Large gears used in marine gearboxes must be designed with as little weight as possible. The requirements of sufficient stiffness of the gear wheel body, as well as the meshing stiffness, must be met. This paper is devoted to the influence of spur gear wheel body parameters on gearing deformation and meshing stiffness. The stiffness of the gear is solved on the basis of the deformation of the gearing teeth, which is determined by the finite element method. Examples of the simulation and subsequent processing of results demonstrates how the individual parameters of the gear wheel body influence the stiffness of the gearing teeth. At the same time, the results point to designs of suitable shape and dimensions to achieve the required stiffness of the gearing teeth, but with the lowest possible weight of the spur gear wheel body.


Author(s):  
Marius Fürst ◽  
Joshua Götz ◽  
Michael Otto ◽  
Karsten Stahl

AbstractIn order to respond to a shortened development time of today’s transmission systems, the automation of certain steps in the design process is essential for ensuring an efficient development process. Computer-aided tools are widely used for analyzing given design configurations because standardized methods are available to evaluate the load carrying capacity of all key components of a simple gear train, namely bearings, shafts and gears. At an early stage of development, requirements and restrictions need to be synthesized to design concepts. During this step, engineers typically rely on their experience and proven practice. Design optimization usually is achieved through an iterative and time-consuming process of analyzing and tuning towards an optimization objective. In this paper a time-saving, automated and systematic method for the design of weight optimized helical gearboxes is proposed. The underlying method has been derived from both, norms and guidelines, which exist for the design and layout of shafts, bearings and gear wheel bodies. Starting with only few input parameters, a detailed shaft geometry with different diameter sections can be derived. A discrete set of values from standard tables and rolling bearing catalogs represents the method’s framework for all realizable shaft diameters in each section. A mixed integer nonlinear optimization problem results from the interdependence between these distinct values. For this purpose, a systematic iterative approach has been developed and implemented in an established design program for gearbox systems. The algorithm uses the results drawn from an analytical calculation of the shaft load carrying capacity to directly adjust the shaft’s diameter and length values. The dimensioning of the wheel body, the service life calculation of rolling element bearings and the selection of specific machine elements are embedded in a systematic sequence. As a result, the model is capable to work out a weight-optimized gearbox that consists of gear meshes, shafts and bearings, taking all three components into consideration at a time.


Author(s):  
O. Pilipenko ◽  
D. Kolesnik ◽  
A. Berezniak ◽  
R. Kholodnyi

The types and methods of modifications of teeth and gear wheels, which have found application in gearboxes of aircraft and helicopters, are presented. Features of geometry, parameters of different types of initial produced contours, their modifications, application and influence of various factors on improving the operational characteristics of gear drives of aviation gearboxes are considered. Arcuate (short and long) and short linear options for modifying the tooth profiles of aircraft gearboxes are best suited to absorb the errors of spur gears. There was no significant difference in the use of short and long correction for a relative decrease in temperature in the contact zone of the wheel teeth, therefore, the use of any correction of the tooth profile, with rare exceptions, turns out to be useful. The advantages of using increased profile angles in comparison with the standard ones used in general mechanical engineering are considered. Development of designs of teeth and gear wheels in aircraft gearboxes, the use of gears with teeth of an asymmetric profile, which can be considered as a cardinal modification of the tooth profiles. The use of such gears increases the strength of the teeth due to the increase in the thickness of the teeth. Unsymmetrical teeth have a large thickness at the tip, which reduces teeth chipping and due to their greater height, greater smoothness of engagement is achieved, bending and contact stresses are reduced. The most radical type of modification is the use of asymmetric profiles of the teeth of the wheels of aircraft gearboxes.


Author(s):  
В.В. Куц ◽  
А.А. Панин ◽  
Д.Н. Тютюнов ◽  
К.В. Жилина

Предлагается краткий обзор промышленного производства червячных фрез. Показано, что повышение качества и производительности изготовления зубчатых колес является необходимым условием снижения себестоимости и расширения объемов производства зубчатых колес на отечественных предприятиях. Главным требованием, предъявляемым к зубьям данной фрезы, является то, чтобы в результате заточки по передней поверхности, которая лежит в осевой плоскости фрезы, профиль зубьев сохранялся до почти полного их износа. Поэтому особое внимание уделяется выбору кривой затылования с учётом целого ряда факторов, способствующих совершенствованию процесса обработки. Отмечено, что затылование имеет ряд преимуществ, в сравнении с острой заточкой фрез. Изложен новый подход к проектированию рабочей оснастки для обработки малых колес циклоидной передачи и исследованы теоретически допустимые интервалы изменения задних углов при затыловании. Установлено, что несмотря на преимущества циклоидальной фрезы перед другими типами затылованных фрез в скорости и точности обработки, она имеет один недостаток - довольно малый промежуток применимости на дуге циклоиды. На основе существующих подходов разработан вариант затылования зубьев червячной фрезы по циклоиде The article provides an overview of the industrial production of hob cutters. We show that improving the quality and productivity of gear wheel manufacturing is a necessary condition for reducing the cost and expanding the production of gear wheels at domestic enterprises. The main requirement for the teeth of this cutter is that, as a result of sharpening on the front surface, which lies in the axial plane of the cutter, the profile of the teeth remains sharp until they are almost completely worn out. Therefore, we paid special attention to the choice of the relief curve, taking into account a number of factors that contribute to the improvement of the processing process. We note that relief has a number of advantages in comparison with sharpening of cutters. We give a new approach to the design of working equipment for processing small cycloidal wheels and investigate the theoretically permissible intervals of variation of the rear angles during relief. We established that despite the advantages of a cycloidal cutter over other types of undercut cutters in terms of speed and machining accuracy, it has one drawback - a rather small range of applicability on the cycloid arc. On the basis of existing approaches, we developed a variant of the relief of the teeth of the worm cutter along the cycloid


Author(s):  
N. I. Kitaev ◽  
S. Ya. Pichkhidze

This article studies the static strength, static fracture and stiffness of the teeth of a wheel made of structural alloy steel of 12KhN3А grade before and after the carburizing of the working surface. The results of the analysis show that the static strength and static destruction of the part before and after chemical heat treatment are approximately equal, however, the gear wheel, strengthened by this method, has a higher hardness. The study and simulation of the applied loads were carried out using a 3D-model in the SolidWorks 2018 Simulation software.


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