• Journal of Mechanical Science and Technology
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• 제18권8호
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• pp.1319-1326
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• 2004

Transient 3-dimensional elasto-hydrodynamic lubrication (EHL) analysis is performed on the contacting teeth surfaces of involute spur gears. Kinematics of the gear and the pinion are taken into account to get accurate geometric clearance around the EHL region of the contacting teeth. The surface pressure and film thickness distribution for the whole contact faces in a lubricated condition at several time steps are obtained through the analysis. Besides the pressure spike at the outlet region, a representative phenomenon in EHL regime, the pressure at the inlet region is slightly higher than that of the center region. The film thickness of transient condition is thicker than that of steady condition.

• 동력기계공학회지
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• 제12권6호
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• pp.78-82
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• 2008

Plastic gears are more and more widely used in many industrial machine elements. Plastic gear has higher properties such as light weight, wear resistance, and vibration absorbing ability than metallic gears. But, in case of using an inaccurate plastic gear, its tooth breakage happen and fatigue life is shortened due to increase of applying load and temperature rising on the tooth flank. Inaccuracy of plastic gears such as pitch circle roundness and tooth profile generates vibration and noise. In this study, an internal plastic gears which is molded by a new injection mold structure are developed. The new mold structure is called the HR3P(hot runner type 3plate mold) that has an improved runner system in order to have good filling balance. As a result from this study, an internal gear with very accurate roundness was developed by using design of experiment.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.81-82
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• 2002

A non-steady 3-dimensional elastohydrodynamic lubrication analysis was performed on the contacting teeth surfaces of involute spur gears. Kinematics of the gear and the pinion were taken into account to get accurate geometric clearance around the elastohydrodynamic lubrication region of the contacting teeth. Pressure and film thickness distribution for the whole contacting faces in lubricated condition at several time steps were obtained through the analysis. Besides the pressure spike at the outlet region, a representative phenomenon in elastohydrodynamic lubrication regime, the pressure at the inlet region was slight higher than that of the center region. The film thickness of non-steady condition was thicker than that of steady condition.

• Tribology and Lubricants
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• 제19권2호
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• pp.65-71
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• 2003

An elastohydrodynamic lubrication analysis was performed on the contacting teeth surfaces of involute spur gears. Kinematics of the gear and the pinion were taken into account to get accurate geometric clearances around the elastohydrodynamic lubrication region of the contacting teeth. Pressure and film thickness distribution for the whole contacting faces in lubricated condition at several time steps were obtained through the analysis. Besides the pressure spike at the outlet region, a representative phenomenon in elastohydrodynamic lubrication regime, the pressure at the inlet region was slightly higher than that of the center region. The film thickness of transient condition was thicker than that of steady condition.

• 한국기계가공학회지
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• 제3권3호
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• pp.64-70
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• 2004

The sub-surface stress field beneath the spur gear's contact surface in lubricated condition has been analysed. The surface pressure was obtained by the elasto-hydrodynamic lubrication analysis using the accurate geometric clearances around the contact region of the teeth. The sub-surface stress field was calculated by using the Love's rectangular patch solution. The analysis results show that the sub-surface stress distribution is quite dependent on the surface pressure distribution. The pattern of sub-surface stress field is similar to that of the external load. The depth where the maximum effective stress occurs is not proportional to the intensity of the external load.

• 수산해양기술연구
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• 제53권3호
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• pp.219-227
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• 2017

In pelagic longline, deploying the gear such that the depth of the hook is the same as that of the target fish is important to improve the fishing performance and selectivity. In this study, the depth of the tuna longline hook was estimated using the mass-spring model, catenary curve method, and secretariat of the pacific commission Pythagorean method in order to improve the performance of the longline gear in Fiji. The former two methods were estimated to be relatively accurate, and the latter showed a large error. Further, the mass-spring model accounted for the influence of tidal current in the ocean, which was found to be appropriate for use in field trials.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.373-378
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• 2013

Impact wrench has a sophisticated structure to implement various pre-designed mechanisms with specific functions. In the structure of impact wrench, the gear box has an important role to generate impacting force of anvil from actuating torque. Since, it requires to design systematically the gear box for accurate mechanism of operation and transferring motions. In this paper, a methodology of dynamic analysis, which is useful to design mechanical system, is proposed and applied to impact wrench, sequentially. At first, the way to perform dynamic analysis for design, which is progressed from component to assembled system, is introduced. Secondly, the proposed methodology is applied to designing impact wrench. Eventually, the results of parameter study with proposed methodology are applied to actual design for design optimization. And optimized-design is evaluated in the view of accurate operation and structural stability.

• Journal of Computational Design and Engineering
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• 제1권1호
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• pp.27-36
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• 2014

Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufacturability (and its limitation in logarithmic spiral bevel gears) is analyzed using precision forging and multiaxis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multiaxis freeform milling also need to be solved in a further study.

• 소성∙가공
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• 제16권8호
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• pp.575-581
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• 2007

The high dimensional accuracy of the cold forged part could be acquired by the accurate dimensional modification for the die, which is, the dimensional changes from the die through forged part to final part after heat treatment were considered. The experimental and FEM analysis are performed to investigate the dimensional changes from the die to final part on cold forged part, comparing with the machined gear. The dimension of forged part is compared with the die dimension at each stage, such as, machined die, cold forged part, and heat-treated-part. The elastic characteristics and thermal influences on forging stage are analyzed numerically by the $DEFORM-3D^{TM}$. The analyzed residual stress of forged part is considered into the FE-analysis for heat treatment using the $DEFORM-HT^{TM}$. The effects of residual stress affected into the dimensional changes could be investigated by the FEA. Each residual stress of gears was measured practically by laser beam type measurement.

• 수산해양기술연구
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• 제48권4호
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• pp.301-309
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• 2012

A net-assembling company for gill net fishing gears makes a design based on the size of nets provided and determines floats, types of weights, and numbers. In addition, through the accurate examination of net weights in the process of fishing gear designing, it can prevent an excessive use of designing costs. The weight of twine can be easily calculated by its thickness differences, but the weight of netting has errors to be calibrated since the weight of netting is not changing exponentially with the changes of number and size of meshes. This study aims to suggest and empirically analyze the methods for estimating the weights of netting in accordance with the changes of number, size and thickness of meshes for a sound management of netting and net-assembling companies. Results indicated that the method using the knots and legs of netting was not practically usable because the errors were increased as the number of mesh increased. However, the method using netting area shown its usage potentiality with the calibration of the increasing ratio of mesh numbers.