• Journal of the Korean Society for Precision Engineering
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• v.16 no.12
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• pp.168-173
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• 1999

It is investigated that internal defect of planetary gear which consists of two gears with different number of teeth on both side. The internal defect, central burst, begin to form at the place of adiabatic shear band which usually has maximum ductile fracture value during the forming operation, forward and backward extrusion. It makes the plastic forming of planetary gear difficult. The prediction of defect to minimize the cost to produce the planetary gear. The finite element simulation code DEFORM is applied to analyze the defects. In the analysis, the toothed gears are assumed as axisymmetric cylinders whose diameters are equal to those of pitch circles of the each gears. Experiments were carried out with the SCM415 alloy steel as billet material and AIDA 630-ton knuckle-joint press. The calculated results and experimental inspections are compared to design a die and blank without defects and the results are useful to predict the internal defect.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.57-65
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• 2016

The power flow of an 8-speed automatic transmission was analyzed using a lever analogy for the manufacturing of planetary gears. From the analysis, we found that the engine power was split between the first and second double-pinion planetary gears (DPPG1 and DPPG2), and was then passed to the DPPG3 for the fourth speed. For the fifth speed, the engine power was split between the DPPG1 and DPPG3. For the speeds 6-8, the engine power was passed only to SPPG2, while the seventh speed contained the power circulation.

• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.15-20
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• 2011

This study deals with the effect of the shot peening in SCM420H planetary gears. The hardness and roughness of the gear surface can be improved by shot blast and shot peening. there in, the shot peening techniques are welcomed especially as one of the physical surface improvement methods. The two treatments are used widely, because of the qualitative analysis of shot blast and shot peening has become possible and the surface treatment can be done with little costs compared with other surface improvement methods. Therefore, this study investigates the effects of shot blast and shot peening in surface shape. The fatigue strength test at a constant stress amplitude is performed by using an electrohydraulic serve-controlled pulsating tester. And fatigue test also explained characteristics of shot blast and shot peening of planetary gears.

• Tribology and Lubricants
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• v.35 no.1
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• pp.71-76
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• 2019

The differential planetary gear reducer as a main component of the concrete mixer driving mechanism requires a strong torque to mix concrete compounds. As this component is currently dependent on imports, it is necessary to develop it by conducting a study on vibration analysis and the resonance problem. The noise and vibration of a concrete mixer reducer increase owing to the transmission error of planetary gears, and the damage of components occurs owing to the problems in design and production. In this study, the tooth-passing frequency is calculated to evaluate the noise and vibration of a mixer reducer, and a fast Fourier transform (FFT) analysis is conducted through a vibration test using an acceleration sensor. The vibration of the reducer is measured at three points of input and output of the shaft and planetary gear housing with fixed and variable revolutions per minute. The operating conditions of gears and bearings are evaluated by performing the FFT analysis, and the resonance problem is verified. The results show that No. 1 pinion and ring gears revolve disproportionately. The amplitude values appear high, and the wear of tooth faces occur in tooth-passing frequencies and harmonic components of No. 1 and No. 2 pinion-ring gears. Therefore, we conclude that design changes in the reducer and a correction of tooth profiles are required.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.108-116
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• 2005

Transplanting accuracy of a rice transplanter mainly depends on the trajectory of the hoe for picking, conveying and transplanting of seedlings as well as the return motion. The trajectory can be decided and prescribed to be suitable in treating seedlings fur a prevailing soil condition. For the purpose of the transplanting accuracy, the design of a transplanting mechanism would be carried out using a planetary-gear-train system instead of the four bar linkage system. In this study, a design method of transplanting mechanism is theoretically proposed by synthesizing a noncircular planetary-gear-train system fur the tool (hoe) to trace a prescribed trajectory. The method utilizes an optimization approach to decide the lengths of an arm and a tool, the inverse kinematics to figure out the configuration angles of the two links, the roll contact condition in transmitting motion between the gears, and a linearization approach to obtain the shapes of the gears. Based on the proposed method, the shapes of the gears and the lengths of the tools of the planetary-gear-train system are determined fur three prescribed trajectories. A kinematical simulation with a commercialized package program is also carried out to confirm that the gear-train system synthesized with the proposed method is able to trace the prescribed trajectory.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.5
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• pp.48-56
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• 2016

In this paper, we analyze the power flow of an eight-speed automatic transmission by using a lever analogy for the manufacturing of planetary gears. The results indicate that the engine power is passed down to the carrier and ring gear in the first double pinion planetary gear (DPPG1), and to the sun gear, carrier, and ring gear in DPPG3 for the first speed. Although the power flow is similar in the second speed, the power circulation occurs in the second single pinion planetary gear (SPPG2). For the third speed, the engine power is passed from the carrier to the ring gear in DPPG, at which point the power is split between the sun gears of SPPG2 and DPPG3.

• Journal of Biosystems Engineering
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• v.22 no.4
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• pp.497-502
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• 1997

Automation facilities of greenhouses have been continuously developed. However, the conventional two-stage worm gear reducer reveals some problems, including low transmission efficiency. The worm gear reducer also have some difficulties in manufacturing and short life. Therefore, this study was performed to develop a planetary gear reducer, having a high Sear reduction ratio and high torque transmission efficiency. The planetary gear system consisted of a fixed ring gear and a 2-teeth differential ring gear turning slow, as the planetary pinion orbits fast around the fixed ring gear. The developed gear system can achieve a high speed reduction rate at one stage. The reducing system was employed to the greenhouse ventilation system. The reducer has the transmission efficiency of 70.5%, 2∼3 times longer life time, and twofold roll-up torque at an affordable price, comparing with conventional reducers. This reducer can be also applied to many industrial equipments, such as industrial crane, hoist, elevator and gondola etc.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.5
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• pp.28-34
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• 2014

A planetary gear train is more compact and endures greater amounts of transmission power compared to other gear systems. Although planetary gear systems operate in small volumes, they are capable of very high efficiency due to the compact combination of their gears in the planetary gear system. They also have outstanding efficiency of only 3% for power transmission, tantamount to the power loss that occurs in each of the shift stages. Given these advantages, planetary gear systems are used in the driving systems of, which are widely used in automobile transmissions, machine tools, semiconductor equipment, and in other areas in industrial fields. Current structural equipment requires higher efficiency and greater torque levels. According to these needs, we have designed a complex planetary gear system which creates higher levels of torque. In this paper, an evaluation of strength designs for the proposed planetary gear system was conducted to ensure the stability of the gear. In addition, a durability analysis based on Miner's rule was performed using RS B 0095 device.

• Journal of Drive and Control
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• v.12 no.4
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• pp.77-81
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• 2015

In general, the gears of mixer reducer for concrete mixer truck make use of the differential type planetary gear system to rotate mixer drum smoothly on the initial conditions. The planetary gear system is very important part of mixer reducer for concrete mixer truck because of strength problem. In the present study, calculating the gear specifications and analyzing the gear bending & compressive stresses of the differential planetary gear system for mixer reducer are necessary to analyze gear bending and compressive stresses confidently, for optimal design of the planetary gear system in respect to cost and reliability. As a result, analyzing actual gear bending and compressive stresses of the planetary gear system using Lewes & Hertz equation and verifying the calculated specifications of the planetary gear system, evaluate the results with the data of allowable bending and compressive stress from the Stress-No. of cycles curves of gears.

• Journal of Drive and Control
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• v.14 no.4
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• pp.71-78
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• 2017

The power train of hydro-mechanical continuously variable transmission (HMCVT) for 8-ton class forklift includes hydro-static units, hydraulic multi-wet disc brake & clutches and complex helical & planetary gears. The helical & planetary gears are key components of HMCVT's power train wherein strength problems are the main concerns including gear bending stress, gear compressive stress, and scoring failure. Many failures in power train gears of HMCVT are due to the insufficient gear strength and resonance problems caused by major excitation forces, such as gear transmission error of mating gear fair in the transmission. In this study, wherein excitation frequencies are the gear tooth passing frequencies of the mating gears, a Campbell diagram is used to calculate the power train gears' critical speeds. Mode shapes and natural frequencies of the power train gears are calculated by CATIA V5. These are used to predict resonance failures by comparing the actual working speed range with the critical speeds due to the gear transmission errors of HMCVT's power train gears.