• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.11
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• pp.1453-1459
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• 2011

A roller pinion gear (RPG) system composed of either a pin or a roller and its conjugated cam gear can improve the gear endurance from that of a conventional gear system by reducing the sliding contact while increasing the rolling motion. In this paper, we first proposed the exact cam gear profile and the self-intersection condition obtained when the profile shift coefficient is introduced. Then, we investigated the Hertzian contact stresses and the load stress factors while the varying the shape design parameters to predict the gear surface fatigue life, which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.2
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• pp.283-289
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• 2012

Cam rack pinion (CRP) system which consists of cam rack and roller pinion transforms the rotation motion into linear one. The roller pinion has the plurality of rollers and meshes with its conjugated cam rack. The exact tooth profile of the cam rack and the non-undercut condition to satisfy the required performance have been proposed by introducing the profile shift coefficient. The load stress factors are investigated by varying the shape design parameters to predict the gear surface fatigue limit which is strongly related to the gear noise and vibration at the contact patch. The results show that the pitting life can be extended significantly by increasing the profile shift coefficient.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.523-526
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• 2000

This paper performs the motion analysis for a disk cam and a follower mechanism using a circular arc method, a coordinate transformation method and an instant velocity method in order to find a contact point between the cam and the follower. Based on the proposed method, the displacement and the velocity are calculated by using the geometric relationships of the cam mechanism. Also, the acceleration is determined on using the central difference method. As the results, this paper presents the original curve and the analyzed curve for the motion analysis of the disk cam for an example.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.639-642
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• 1997

A cylindrical cam with a translation roller follower provides to transfer the translation motion and it s very useful mechanism in the automation. But. it's very difficult that the shape is defined accurately. This paper, proposes a new shape design method of the cylindrical cam with translation roller follower using the relative velocity method[l]. The relativc velocity method lculates the relative velocity of the follower versus the cam at a center of roller, and then determines a contact point by using the geometric relationships and the kinematical constraints. Finally, we present an example in order to prove the accuracy of the proposed methods.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.916-919
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• 2002

Cam mechanism is one of the common devices used in lots of automatic machinery. This paper introduces to an inverse cam mechanism. The inverse cam mechanism has a reverse structure as compared with common cam mechanism. For shape design of the inverse cam the approach used in this paper is an instant velocity center method that find the contact point between cam and roller at any contact time. And a computer program is developed for shape design and simulation by visual $C^{++}$ language. As the results, this paper presents two examples for the shape design of the inverse cam mechanism in order to prove the accuracy of the design procedures.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.6
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• pp.147-154
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• 2000

A numerical procedure to analyze 3-dimensional elastohydrodynamic lubrication was applied on the cam-roller contact of the valve mechanism for a marine diesel engine. Both the pressure distribution and the film thickness between the cam and roller follower were calculated for each time step of the whole cycle. The pressure spike is shown at the outlet of the roller edge and it is getting higher as the external load is increased. An effective profiling method for the roller edge was suggested using the results of elastohydrodynamic lubrication analysis and the peak pressure was removed completely with the new profiling.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.121-128
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• 1999

In this study, a numerical procedure to analyze 3-dimensional unsteady elastohydrodynamic lubrication was developed. The procedure was applied to the actual cam and roller follower of the valve mechanism for a marine diesel engine. The pressure distribution between the cam and roller follower was calculated for the several cam rotating angles. The pressure spike is shown near the roller edge and it is getting higher as the external load is increased. The roller profile for reducing the pressure spike was suggested by the Hertzian contact analysis.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.117-117
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• 2004

일반적으로 접촉 피로 마멸은 구름 또는 미끄럼 접촉시 작용하는 반복 응력에 의해 표면과 표면 아래에 균열이 형성되고 성장 및 합체의 과정을 거쳐 표면의 일부가 떨어져 나가는 손상으로 기어나 캠-롤러, 구름 베어링과 같이 구름-미끄럼 접촉상태로 운전하는 기계요소에서 가장 중요하게 고려되어야 할 파손 메커니즘이다. 특히 기어나 구름 베어링 같이 고주기 접촉 피로 특성을 지니는 기계요소의 수명은 피로수명 실험과 통계적 기법을 이용한 Weibull 이론을 기초로 한 수명식을 대부분 사용하고 있다.(중략)

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.113-119
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• 2000

There are two major factors which affect the cam design : the pressure angle and the radius of curvature, Cam shape will have an instantaneous radius of curvature at every point. Even though the design constraint of the pressure angle has been satisfied the follower may still not complete the desired contact motion. If the radius of the follower roller is larger than the concave(negative) radius on the cam it occurs the gap between the cam and the follower roller at the contact point. And also if the curvature of the pitch curve of the cam is too sharp the cam profile may be undercut. This paper proposes a new approach which uses the relative velocity of the follower roller parallel to the tangent line at the contact point on the cam surface for determining the pressure angle and the relative acceeration for determining the radius of curvature.