• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.48-53
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• 1999

In this paper, a practical method for design and machining of cycloid gear was investigated. Based on the proposed method, a systematic program was developed for automatically designing the tooth profiles of epicycloid and hypocycloid gears for the case fo one difference between the number of teeth of cycloid gear and the number coordinates of tooth profiles and pressure angles. The error analysis between cycloid curve and Biarc curve was performed to show the effective method of equidistant partitioning of cycloid curve so that efficient method of Biarc curve fitting was also proposed for the partitioned curve.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.1
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• pp.70-80
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• 2001

A cycloid reducer is one of the rotational velocity reduction equipments of machinery. It has advantages of the higher reduction ratio, the higher accuracy, the easier adjustment of transmission ratio and the smaller workspace than other kinds of reducer. A cycloidal plate gear is a main part of the cycloid reducer. Its tooth shape is peculiar because of gearing with the roller gear that has the several rollers on the circular line. And then it can be designed to contact all teeth to rollers. So, the cycloid reducer has the good characteristics in the dynamic properties and the zero-backlash in the contact motion. It can be used in robots, high-precision machines and high capacity machinery. This paper proposes a new approach for the shape design of the cycloidal plate gear and presents a Computer-Aided-Design program developed by the proposed method. The first part of this paper defines the two types of the cycloid reducers and explains their mechanisms. The second part defines the instant velocity centers for each type of the cycloid reducers and calculates the contact angles and the contact points by using te geometric relationships and the kinematical properties of the reducers. The third part generates the full shape of the cycloidal plate gear by the coordinate transformation technique. Finally, this paper presents two examples for the shape design of the cycloidal plate gear in order to prove the theory of the proposed method in this paper and the accuracy of the \"CycloGear Designer\".

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.113-118
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• 2017

In this paper, a study on the performance evaluation of a cycloid reducer for remote weapons systems is presented. Reduction gears applied to remote weapons vehicles need to be compact and capable of large torque transmissions as well as require structural optimization, high load capacity, and high precision position control. To meet these requirements, a cycloid reducer with low backlash, high precision, high overload capability, high rigidity, and high efficiency is required. Thus, a cycloid reducer with a reduction ratio of 127:1, backlash of 1 arcmin (1/60 deg) or less, and reduction gear efficiency of 70% or more, which are the design requirements for a remote weapons system, was designed utilizing a design and analysis program (HEXAGON) for gear engineering. To confirm the performance of the cycloid reducer, the hardness of the main components of the manufactured cycloid reducer, reduction ratio, and efficiency were measured.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.80-85
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• 2002

The free curve gear is a non-circular gear without any relating center, which can perform free curve motion for complicated mechanisms, and minimize the work area. In this study, an algorithms for tooth profile generation of free curve involute gear is developed. The algorithm uses the involute gear creating principle in which a gear can be generated by rolling with another standard involute one. Cycloid me and third polynomial curve gears were designed and verified by computer graphics. These gears are manufactured in the wire-cut EDM and examined in engagement with a standard spur gear. The results showed that the proposed algorithm is successful to design and to manufacture the free curve gear with concave and convex profiles.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.46-52
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• 2004

The most of reducers consist of many gear parts, but a ball reducer never contains a gear. As the ball reducer with gearless has no back lash, it is necessary more and more to precision machine. The reducing of ball reducer happens by cycloid curves and all instant relative velocity centers always pass on a given constant position when rotational running. Then, it is difficult to calculate cycloid curve for design and machining. So, this paper studied a software for the design of the ball reducer design and machined all parts included among cycloid curve. By using the developed software, this study has large benefit to design every ball reducer.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.9
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• pp.895-902
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• 2015

In this paper, finite element analysis of a cycloidal pitch reducer for a 2 MW-class wind turbine is reviewed. The system is composed of one cycloid set, one spur gear set, an input shaft, an output shaft, and a housing. The system was also evaluated for stability by analyzing spur gear strength according to ISO 6336. An analysis of the natural vibration characteristics of the 2 MW-class wind turbine cycloid pitch reducer was performed with attention to critical speed with input mass unbalance, output mass unbalance, spur gear transmission error, cycloid gear transmission error, and excitation frequency.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.1
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• pp.1-10
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• 1993

A design method of gear tooth profile which can reduce the noise of gear is studied. The tooth profile is generated by combining involute and cycloid tooth curves in which the involute tooth profile is near the pitch point and cycloid tooth profile at the addendum and the dedendum. Considering parameters which have an influence on the reduction of gear noise and building up a design conditions for the noise reduction of gear, the lower-noise combined gear tooth profile is designed. For the check of noise reduction of the combined gear profile, two pairs of combined profile gear, two pairs of involute gear, and a pair of cycloid gear were manufactured by the NC Wire Cutting Machine, and the experiment for measuring of gear noise was carried out on each pair. The noise reduction of the combined profile gear was obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.816-821
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• 2005

The cycloid reducer has very high efficiency, high ratios, high stiffness and small size, in comparison with a conventional gear mechanism, which makes it an attractive candidate for limited space and precision application such as industrial robot. There are several publications on analysis and design of the cycloid reducer, however, it was assumed that the contact stiffness of pin rollers and cycloid disk is constant regardless of their contact geometry. Moreover, the torsional stiffness of the cycloid reducer couldn't be calculated due to the assumption. In this paper, we present a new procedure of calculating torsional stiffness of the cycloid reducer using Hertz contact theory. First, conventional force analysis of the cycloid reducer is briefly reviewed. Then, iterative numerical calculation procedure of the contact stiffness is proposed based on the Hertz contact theory where the contact stiffness depends on the contact force. In addition, total torsional stiffness of the cycloid reducer is estimated considering its rolling element bearing stiffness. The torsional stiffness of the cycloid reducer is dominated by the rolling element bearing stiffness since the contact stiffness of the cycloid disk is too large.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1217-1224
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• 2009

This paper presents a finite element (FE) analysis of the torsional rigidity of a two-stage cycloid drive. The cycloid disk makes contact with a number of pin-rollers simultaneously and eccentric shafts transmit not only torque of the spur gear stage to the cycloid disk, but also that of the cycloid disk to the output disk. Contacts between the disk and pin-rollers are simplified as linear spring elements, and the bearing of eccentric shaft is modeled as a rigid ring that has frictional contact to the disk and an elastic support. FE analysis for an ideal solid cycloid drive was performed and verified by a theoretical calculation. Accurate contact forces were then estimated by iterating between FE analysis for contact forces and Hertz theory calculations for nonlinear contact stiffness. In addition, torsional rigidity of the cycloid drive is analyzed to show that the bearing and nonlinear Hertz contact theory should be considered in analysis and design of a cycloid drive, which was verified with experiments. Finally, the effects of contact stiffness, bearing stiffness and cycloid disk structural stiffness according to the cycloid disk rotation on the torsional rigidity were investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1398-1401
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• 2004

This paper proposes a new approach for the shape design of the rotating outer-ring type epicycloid plate gear by using instant velocity center. First, this method defines the instant velocity centers for rotating outer-ring type epicycloid plate gear and calculates the contact angles and the contact points by using the geometric relationships and the kinematic properties of the reducer. Second, it generates the full shape of the cycloidal plate gear. Finally, the paper develops CAD-program for construction of the design automation using the proposed method. This CAD-program is developed to have the functions of the friendly user interface and the simulation of the real operation for the cycloid reducer.