• Tribology and Lubricants
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• v.29 no.6
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• pp.353-359
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• 2013

The rollers and/or races in cylindrical and tapered roller bearings should be profiled to relieve high edge stress concentrations caused by their finite lengths and misalignment. In this study, a numerical analysis was performed to investigate the elastohydrodynamic lubrication (EHL) of a Lundberg profile-type cylindrical roller. A finite difference method with fully nonuniform grids and the Newton-Raphson method were used to present detailed EHL pressure distributions and film shapes, as well as the variations in the minimum and central film thicknesses with the profile modification coefficient. In the Lundberg profile, the maximum pressure and minimum film thickness always occurred near the edges. Proper modification of the Lundberg profile considerably increased the minimum film thickness.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.3
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• pp.299-305
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• 2017

Gate-lifting devices in small- to mid-sized sluice gates mostly employ the mechanical roller rack pinion (RRP) system. This RRP system, which consists of a rack-bar and a pinion, transforms a rotation motion into a linear one. The rack-bar has a series of roller trains that mesh with the pinion. In this study, we adopt an exact involute-trochoid tooth profile of the pinion to obtain a higher contact fatigue strength using the profile modification coefficient. Further, we determine the contact forces and investigate Hertz contact stresses to predict the pitting life of the pinion according to varying the shape design parameters. The results indicate that the design fatigue life of an RRP system for sluice gate can be achieved only when the design value of the profile modification coefficient reaches or exceeds a certain level.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.4
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• pp.38-43
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• 2011

Industrial reducer is in general use to Deck Crane. High-precision and high-efficient reducer is minimized the power-loss and energy-loss of a machine. So it contribute the price reduction and life extension. Reducer is usually using the Planetary gear reducer. Planetary gear reducer is composed the sun gear, planet gear, internal gear and casing. Industrial reducer's wear and breakage have a short-life. To solve this problem, it is using the profile-shifted-gear or tooth modification. This study was carried out the effect of addendum modification coefficient on tooth fillet bending strength to planetary reducer. Tooth fillet bending stress is calculate. And all parameter were expressed the function of addendum modification coefficient. And then stress concentration factor of tooth fillet curve was express the function of addendum modification coefficient using comparison between theory and finite element analysis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1391-1397
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• 2012

A cam ring gear (CRG) system based on a hypotrochoid curve consists of a pinion with roller teeth and its conjugated internal CRG. In this study, we investigated contact forces, contact stresses, and load stress factors to predict the surface pitting life using an exact CRG profile by introducing the profile modification coefficient. The results show that the pitting life can be extended significantly by increasing the profile modification coefficient without any other change of parameters in the CRG system.

• Tribology and Lubricants
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• v.4 no.2
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• pp.60-67
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• 1988

Conventional theory of gear mechanism can't be applied to analyze the harmonic drive due to specific movement of the teeth. This paper deals with an analysis of kinematics and geometry of the tooth engagement of a harmonic drive comprising circular spline, flexspline and wave generator. A theoretical new tooth profile of the flexspline in meshing internal rigid gear with involute profile is obtained. Characteristics of harmonic drive reducer are shown according to parameters such as deviation coefficient, deviation distance, addendum modification coefficient. As an example, the design of harmonic drive with 1:80 reduction ratio is presented.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.1
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• pp.21-29
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• 2016

To overcome the large ring gear manufacturing problems seen in slewing bearings and girth gears, pin gear drive units have been developed. Among them, a novel slewing bearing with an internal pinwheel gear set (i-PGS) is introduced in this paper. First, we consider the exact cam pinion profile of i-PGS with the introduction of a profile shift coefficient. Furthermore, a new root relief profile modification for the i-PGS cam pinion is presented. Then, the contact stresses are investigated to determine the characteristics of the surface fatigue by varying the shape design parameters. The results show that the contact stresses of i-PGS can be reduced significantly by increasing the profile shift coefficient. In addition, the contact ratio, a measure of teeth overlapping action, decreases with the decrease of the allowable pressure angle.

• Tribology and Lubricants
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• v.5 no.2
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• pp.107-112
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• 1989

This paper deals with strength analysis of tooth and method of manufacture of external tooth profile in harmonic drive. From the calculation of load imposed on the contact teeth, moximum contact stress is investigated to design the addendum modification coefficient. New tooth profile of the external gear is generated according to the law of gearing, assuming that internal gear has involute tooth profile. External tooth profile can't be manufactured by conventional exclusive tools which have pressure angle of 20$\circ$. The method to design cutter tooth profile is presented.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.124-130
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• 2005

The research on surface modification technology has been advanced to improve the properties of engineering materials. ion implantation is a novel surface modification technology to enhance the mechanical, chemical and electrical properties of substrate's surface using accelerated ions. In this research, nitrogen ions were implanted into aluminum substrates which would be used for mold of rubber materials. The composition of nitrogen ion implanted aluminum alloy and nitrogen ion distribution profile were analyzed by Auger Electron Spectroscopy (AES). To analyze the modified surface, properties such as hardness, friction coefficient, wear resistance, contact angle, and surface roughness were measured. Hardness of ion implanted specimens was higher than that of untreated specimens. Friction coefficient was reduced, and wear resistance was improved. From the experimental results, it can be expected that ion implantation of nitrogen enhances the surface properties of aluminum mold.

• Transactions of Materials Processing
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• v.3 no.1
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• pp.97-109
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• 1994

Closed-die forging of the spur gears with circular are fillet has been analyses by using the upper-bound method. A kinematically admissible velocity field has been developed, wherein, the tooth profile consists of the involute curve and the circular arc fillet. In the analysis, the deformation regions have been divided into eight zones. A constant frictional stress has been assumed on the contacting surfaces Utilizing the formulated velocity field, numerical calculations have been carried out to investigate the effects of various parameters, such as module, number of teeth, addendum modification coefficient and friction factor, on the relative forging pressure of spur gears. As the result of numerical calculations, the relative forging pressure does not change so much against the variation of module. On the other hand, the relative forging pressure increases at the final filling stage as the addendum modification coefficient increases.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.4
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• pp.245-252
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• 2016

Girth gears are applied in the mining, cement, and mineral processing industries and used in various types of horizontal mills, rotary dryers and kilns, and other heavy-gear ring applications. The large ring gears are normally fitted outside mills or kilns to provide the primary rotational drive. Recently, an external pinwheel gear set (e-PGS) was introduced to overcome manufacturing problems associated with girth gears. e-PGS is also suitable for low-speed, heavy-duty mechanical transmission and dusty and poor-lubrication conditions. This paper first presents a new profile modification of root relief for the e-PGS cam pinion. We then investigate load-stress factors to estimate the surface fatigue life by varying the shape design parameters. The results show that the contact fatigue life of an e-PGS can be extended significantly by increasing the profile shift coefficient. However, support bearing life of the pinwheel depends more on the contact force distribution than the profile shift coefficient.