• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.153-158
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• 2017

Reducer is a device to transmit and change torque and speed from drive shaft to driven shaft with excellent transmission efficiency, and it is widely used in many areas today. Reduction gear consists of two axes, gear, bearing supporting axes, and housing. The simplest method to transmit rotation or power to multiple axes is to attach circular plates to two axes and contact each other. However, in this case, if increasing number of rotations or if contact pressure is small, because of slipping, it cannot transmit power. For problems for the current reducer case, it is heavy and its assembling and repair is difficult. In addition, there are few studies about manufacturing and performance testing of worm gear reducer, causing lack of the foundation to improve the product competition and the performance.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.439-448
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• 2012

This paper investigates the load sharing of double circular arc helical gears considering the influence of assembly errors. Based on a load sharing formulae, a three-dimensional finite element tooth contact analysis (TCA) is implemented with commercial software package ANSYS. The finite element grid for the double circular arc gear contact model is automatically generated by using the APDL (ANSYS Parameter Design Language) embedded in ANSYS. The realistic rotation of gears is achieved by using a coupling degree-of-freedom method. Numerical simulations are carried out to exemplify the proposed approach. The distribution of contact stress and bending stress under specific loading conditions are computed and compared with those obtained from Hertz contact theory and empirical formulae to demonstrate the efficiency of the proposed load sharing calculation formulae and TCA approach.

• International Journal of Precision Engineering and Manufacturing
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• v.1 no.2
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• pp.94-104
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• 2000

A kinematically admissible velocity field for near-net shape forging of a crown gear form is proposed. This takes into account the profiled shape of the teeth chosen by approximating these kinematically as radially straight taper teeth, (rectangular and trapezoidal teeth). The upper bound to the forging load, the relative forging pressure and the deformed configurations, with both the initially solid circular cylindrical and hollow billets, are predicted using the velocity field at varying incremental punch movements considering differing frictional factors. These and other results are given and commented upon.

• 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 Automotive Engineers
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• v.6 no.1
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• pp.56-62
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• 1984

Various automotive and machine parts are having the shape of circular ring and the study and the verification of its dynamic characteristics can be the important basis of quality control and improvement of performance of inner and outer race of ball and roller radial bearing, ring gear, seal, etc. In this study, three separate sets of governing equations on the flexural vibration of circular ring were formulated each considering the effects of viscous damping, rotatory inertia and shear deformation, and three frequency formulas were derived. Numerical values of frequencies of circular and rectangular cross section ring were tabulated and compared with experimental value. Some important parameters were found in the ring vibration characteristics.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.6
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• pp.577-582
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• 2010

The squeak propensity in the gear box of an automotive seat system is investigated analytically. The mating parts in the gear box are the lead screw and the nut, where the friction stresses are exerted on the thread of the screw. The lead screw is modeled as a circular beam allowing the bending and torsional vibrations. In the system, the lead screw converts rotating to translating motion so that it moves the automotive seat slightly tilted on the floor. The tilting angle is considered one major parameter in this study. Therefore, the equations of motion associated with the non-conservative friction force are derived with the inclusion of the tilting angle. It is found that the squeak noise corresponds to the several bending modes of the lead screw and its propensity is increased by the tilting angle of the seat.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.10a
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• pp.143-149
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• 1995

A simple kinematically admissible velocity field is proposed to drtermine the final-stage extrusion load and the average extruded length in the square-die forward extrusion of non-axisymmetric bars from circular billets. The proposed velocity field is applied to the square-die extrusion of trochoidal gear-shaped bars and rectangular-shaped bars, the profile function of a rectangular being approximated by using a Fourier series. Experiments have been carried out with hard solder billets at room temperature. The theoretical predictions of the extrusion load are in good agreements with the experimental results and there is generally reasonable agreements in average extruded length between theory and experiment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.11
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• pp.837-847
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• 2020

A velocity profile for flapping flight is optimized to increase the power efficiency of 20g weighted flapping wing micro air vehicle in hover. The experimental optimization of flapping velocity profile is carried out with a real sized flapper, and various velocity profiles are realized by non-circular gear. Kriging with noise is adopted as a meta model of the profile optimization to reflect the data noise by uncertainty. The optimization results confirm that the flapping efficiency (thrust-to-power ratio) is substantially improved (11.3%) through the elastic deformation that carries the angular kinetic energy from previous stroke.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.48 no.1
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• pp.51-58
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• 2012

As a basic study to improve hooking ability of long line fishing gear, which is widely used around Jeju-do coast, the researcher performed hooking experiment of parrot fish by manufacturing and installing 7 kinds of model long line fishing gears, whose thickness of branch line are different and 8 kinds of model long line fishing gear, whose length of branch line are different, in indoor circular aquarium, which is installed for the model experiment of thickness and length of branch line that are various by fishing implement and improper. The hooking rate depending on thickness and length of branch line was calculated and the effect of thickness and length of branch line on hooking rate was analyzed. Its results are as follows. When branch line was thin and long, high hooking rate appeared. In the scope of value setting, the relationship between thickness ($B_t$) of branch line and total hooking rate ($Th_r$) can be shown as following formula as. In the scope of value setting, the relationship between length ($B_t$) of branch line and total hooking rate ($B_t$) can be shown as $Th_r=-20.83B_t+26.04$. Through Pearson correlation analysis, the coefficient of correlation between thickness of branch line and hooking rate was -0.718. Therefore it showed significance in 0.01 significance level. Through Pearson correlation analysis, the coefficient of correlation between length of branch line and hooking rate was 0.431. Therefore it showed significance in 0.01 significance level.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.488-491
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• 2006

In this paper, a slim type actuator is proposed rising a bimorph PZT and a circular rotor link. The bimorph contacts the circular rotor, and its displacement generates the rotational motion of the rotor. The rotor causes the linear motion of AF and zoom lens through gear and a motion guide. The proposed model enables the actuations of many lens groups for zoom module by extending the single lens model. The important design parameter is the contact force determined by the frictional coefficient and preload between the rotor and PZT bimorph. A prototype of the single actuator model is manufactured and experiments results using LDV and tachometer are compared to the theoretical and numerical predictions. Experiments show the linear bimorph actuator model meets the performance criteria of the lens actuation, and it can be applicable to various slim type actuators for AF and zoom motions in mobile cameras.