• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.87-90
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• 2004

In this paper, net-shape forming of an automobile gear is investigated. Barrel, a component of automobile start motor, is adopted as a net-shape forming. In order to accomplish the goal of net-shape forming without cutting of tooth and cam after forming, forming ability is raised through billet treatment and die design. As a technique of billet treatment spheroidizing annealing of billet to get low hardness and molybdenum disulphide coating to get low contact friction between billet and die is carried out. One of critical points of die design, fillet radii variation of tooth of die is applied to get smooth surface of barrel after cold forging. As a measurement of tooth accuracy, distance between two pins and lead-tooth alignments are investigated. Cam profile accuracy is checked with a 3D measuring instrument. Results obtained from the tests revealed reasonable result with respect to design goal. By these results, the paper shows that reasonable results can be obtained by billet treatment and die design for net-shape forming.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.11 no.8
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• pp.364-373
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• 2001

The gear whine noise of vehicle transmission is directly correlated tilth the gear transmission error of mating gear The object of this study is to build up the synthesized countermeasure for the reduction of gear whine noire of vehicle transmission by developing the program which can be used to analyze and predict the vibrational characteristics caused by gear transmission error of mating gears of vehicle transmission. The developed mathematical models on the elements of transmission, for example, helical gear pairs, bearings and shafts are used and the modeling of the excitation forces are developed by the gear transmission error of mating gear which is defined by the amount of the elastic deformation of gear tooth & shaft and gear profile & lead errors. The mathematical system model of vehicle transmission developed by the substructure synthesis method Is also verified by the experiments.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.5
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• pp.632-637
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• 2011

A new tooth profile which is adjusted on the amount of addendum modification factor is proposed for reducing vibration and noise of gears. The transmission error of the new profile can be designed more uniformly than that of the standard involute profile. The basic concepts of tooth profile modification are to reduce the load in contact area and to find the appropriate profile modification factor for operation condition. In this study, gears were estimated to constructive safety of bending strength and contact strength durability by using ROMAX program, and were compared with results by design formula of AGMA standard.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3142-3151
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• 1996

As plastics shrink when changing from a molten to a solid state, mold cavities must by made larger than the product specification, In making molded gears, the teeth in the cavity must be carefully compensated for shrinkage so that the teeth of gears will have the correct profile. Two compensation methods are widely used in the cavity design. One is the compensation of a module and the other is the modification of a pressure angle and profile shifting coefficient. These methods, however, do not provide a gear cavity with all disign parameters for gears and several parameters are determined by experience. In this paper, the new design technique, namely the compensation method of design parameters, was proposed , which is based on the three kinds of shrinkage rates obtained from the measuring data of the prototype of molded gears. Using the shrinkage rates in the tip circle, tooth heigth and tooth thickness, we calculate the whole design parameters of a gear cavity. Thus, the gear cavity is considered as a complete gear with the compensated module, pressure angle, profile shifting coefficient, clearance coefficient and back lash amount so that the formula of gears can be applied to the cavity design effectively. Experimental results show that more precision molded gears can be made by using the proposed design method.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.3
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• pp.50-55
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• 2002

A roller gear cam mechanism is presented. It consists of two or more plate cams with particular teeth, called Conjugate Cam Tooth (CCT) and a turret with axially located rollers. A practical and available configuration has been found out by synthesizing its parameters. The profile equations of the conjugate cam are derived by using a relative velocity method. A program fur the design automation of shape of the conjugate cam and the motion simulation of this kind of mechanism has been deve1oped using the derived formulae with C++ language. Finally, an example is given.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.809-810
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• 2008

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.15-20
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• 2014

The wind industry grew in the first decade of the 21st century at rates consistently above 20% a year. For wind turbine, gearbox failure can be extremely costly in terms of repair costs, replacement parts, and in lost power production due to downtime. In this paper, gear tooth micro-modification for the high speed stage was used to compensate for the deformation of the teeth due to load and to ensure a proper meshing to achieve an optimized tooth contact pattern. The gearbox was firstly modeled in a software, and then the various combined tooth modification were presented, and the prediction of transmission under the loaded torque for the helical gear pair was investigated, the normal load distribution and root stress were also obtained and compared before and after tooth modification under one torque. The simulation results showed that the transmission error and normal load distribution under the load can be minimized by the appropriate tooth modification. It is a good approach where the simulated result is used to improve the design before the prototype is available for the test.

• Tribology and Lubricants
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• v.23 no.3
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• pp.117-122
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• 2007

This study deals with the TE (Transmission Error) of gear tooth by modifying a profile and lead of a surface of tooth. First, we experimentally confirmed that the TE is a synthesis of the sliding velocity between both gears. Since various types of TE appear in the experiments, we introduced definition of transmission error and the optimism design by modifying a surface parameters. The test stand's performance is then evaluated through a series of multiple torque transmission error tests. Comparisons are made between data recorded before and after the test stand's redesign, and subsequently repeatability studies are performed to verify the veracity of the measured data. Finally, the experimental results are compared to the analytical predictions of two different gear analysis programs.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.1
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• pp.69-78
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• 1997

Main sources of the vibration in gear driving system are transmission error and backlash. Transmission error is the difference of the rotation between driving and driven gear due to tooth deformation and profile error. Vibro-impacts induced by backlash between meshing gears lead to excessive vibration and noise in many geared rotation systems. Nonlinear dynamic characteristics of the gear driving system due to transmi- ssion error and backlash are investigated. Transmission error is calculated for spur gear. Nonlinear equation of motion for the gear driving system is developed with the calculated transmission error and backlash. Numerical analysis of the equation and the experimental results show the existence of meshing frequency, superharmonic compon- ents. Instability of the gear driving motion is found on the basis of Mathieu equation. Rattle vibration due to backlash is also discussed on the basis if nonlinear jump phenomenon.

• 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.