• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1243-1244
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• 2012

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.90-95
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• 2011

This paper presents the study on the contact stress analysis of a pair of mating helical gears for turbo blower during rotation. Turbo blowers need high speed rotation of impeller in structure and high rate gear ratio. The use of helical gear indicated that noise was an important problem when the application involves high speeds and large power transmission. An example is presented to investigate the variation of contact stress on a pair of mating gears with contact positions. The variation of contact stress during rotation is compared with the contact stress at the lowest point of single tooth contact(LPSTC) and AGMA Equation for contact stress. In this study, the gear design considering the contact stress on a pair of mating gear is more severe than that of AGMA standard.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.132-137
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• 2011

Many studies are being conducted to improve high speed, light weight and safety of passenger. To improve safety of rolling stock, safety of running performance is most important, and optimizing flow lubrication in driving gear is essential. This study simulates lubricant flow change in driving gear casing which is splashed by the surface of low speed gear teeth following rotational direction of driving gear unit for EMU by using CFD analysis, and based on analysis detail, non-load actual test is conducted for similar driving condition to find out suitability of analysis, selection of lubricate and stability of driving gear.

• Journal of KSNVE
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• v.9 no.3
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• pp.593-599
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• 1999

A rotordynamic analysis is performed with a motor-bull gear rotor system supported on two partial bearings, which is intended to drive a high-speed turbo-chiller compressor impeller shaft through its built-in pinion gear. The motor-bull gear rotor system has a rated speed of 3,600 rpm, and is modeled utilizing the finite element method for analysis. As loadings on the bearings due to the gear action are significant in the system considered, each resultant bearing load is calculated statically by considering the generalized forces of the gear action as well as the rotor itself. The two support partial bearings are designed to take their varying loads along with their varying load angles, and they are also analyzed to give their rotordynamic coefficients. Then, a complex rotordynamic analysis of the motor-bull gear rotor-bearing system is carried out to evaluate its whirl natural frequencies and mode shapes and unbalance responses under various loading conditions. Results show that the bearings and entire rotor system are well designed regradless of operating conditions, i.e., loads and operating speeds.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.2
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• pp.57-64
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• 2001

In recent years, the concern of designing multi-stage gear drives ha increased with more application of them in high-speed and high-load. Until now, however, the researches on the design of gear drives have been focused on single gear pairs. Thus the design practice for multi-stage gear drives has been depended on experiences and expertise of designers and carried out commonly by trial and error. We propose an automation algorithm for the design of two-and three-strage cylindrical gear drives. The two types of dimensional design processes have been proposed to determine gear dimensions in a formal way. The first design process(Process I) uses to total volume of gears to determine gear ration , and uses K factor , unit load and aspect ration to determine gear dimensions, The second one(Process II) makes use of Niemann's formula and center distance to calculate gear ratio and gear dimensions. Process I and Process II employ material date from AGMA and ISO standards, respectively. The configuration design determines the positions of gears with minimizing the volume of gearbox by using a simulated annealing algorithm. The availability of the design algorithm is validated by the design examples to two-and three=stage gear drives.

• Journal of Biosystems Engineering
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• v.18 no.2
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• pp.91-99
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• 1993

Kinematic analysis was made on a gear type high speed planting mechanism for riding-type rice transplanters. The kinematic equations thus derived were computer coded to simulate its motion characteristics such as a planting locus, velocities and accelerations of gears and planting knife, etc. Using the simulation program a sensitivity analysis of design parameters was also carried out to determine their effects on the planting performance. Of the design parameters the eccentricity of the gear was found most influential.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.202-209
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• 2000

In recent years the concern of designing multi-stage gear drives increases with the more application of gear drives in high-speed and high-load. until now however research on the gear drive design has been focused on single gear pairs and the design has been depended on experiences and know-how of designers and carried out commonly by trial and error. We propose the automation of the dimensional design of gears and the configuration design for gear arrangement of two-and three-stage cylindrical gear drives. The dimensional design is divided into two types of design processes to determine the dimensions of gears. The first design process(Process I) uses the total volume of gears to determine gear ratio and uses K factor unit load and aspect ratio to determine gear dimensions. The second one(Process II) makes use of Niemann's formula and center distance to calculate gear ratio and dimensions. Process I and II employ material data from AGMA and ISO standards respectively. The configuration design determines the positions of gears to minimize the volume of gearbox by simulated annealing algorithm. Finally the availability of the design algorithm is validated by the design examples of two-and three-stage gear drives.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.20-25
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• 2016

Recently, the requirements for high precision and efficiency machining are gradually increased to raise international competitiveness at the industrial fields of automotive and gears. This trend had made effects on the industrial fields in Korea and which needs further studying of high accuracy and efficiency machining. This study is to investigate the effects of Jig type chuck for roundness improvement in CNC turning machining of high stage speed gear. After hobbing machining, Dimensional change before and after heat treatment was very largely generated. In order to solve this problem was to develop a jig type chuck. After the heat treatment, the operation of the chuck which was the most distinguished equipment among Jig type chuck(0.006mm), Scroll type chuck(0.05mm) and Bolt type chuck(0.04mm). Therefore, Jig type chuck was satisfied the requirement from the actual field(0.02mm).

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.88-98
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• 1990

The purpose of this study was twofold : first, to reduce as much as possible the shaking moments of the crank-type transplanting mechanism of walking-type rice transplanters, and second, to evaluate whether or not a crank-type transplanting mechanism, if its shaking moment is reduced, can be used in riding-type transplanters for high speed transplanting operations. For these purposes, kinematic and force analyses of the currently available crank-type transplanting mechanisms were made and their results were compared with those observed by experimentation. The degree of shaking moment effect was also estimated Various efforts to minimize the shaking moments led to the development of a crank-type mechanism with a balancing gear, in which an eccentric balancing gear is combined into the driven link axis. Analysis of the developed mechanism showed that about 20% of the shaking energy can be reduced and about 40% of reduction in peak shaking moment can be obtained when comparing with those obtained without the balancing gear. It was concluded that crank-type transplanting mechanisms can be used for high speed operations with a forward speed of 0.9-1.2m/s if the balancing gear is additionally mounted. However, further considerations must be made to solve the space constraints in relation to the structural frame of riding type of rice transplanters.

• Tribology and Lubricants
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• v.38 no.3
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• pp.115-119
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• 2022

This paper selected three kinds of grease with the same type but different consistency for the experiment. The purpose of the experiment is tested the effect of different consistency of grease on the wear of the gear surface. Different torque test groups were selected in the test, and the lubrication effect of different greases was tested in the test groups with the same torque. After each set of tests, the wear of the gear surfaces was observed and recorded. The data recorded in the experiment included the area of the wear area on the gear surface, the type of wear and the volume of wear. After the test, the gear surface roughness was measured. By calculating the wear volume, the effects of different concentrations of grease on the gear surface wear were compared. The experimental results show that under different stress conditions, the consistency of the grease has a great influence on the lubricating effect of the gear surface and the gear wear. Under the condition with low speed and high torque, different grease consistency affect the gear surface wear, the high consistency grease can reduce the wear of the gear surface, so that the gear can get better lubrication effect during the work.