• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.431-432
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• 2010

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.44-51
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• 2006

This paper deals with the aspects of die design for the multistage fine tooth hub gear in the cold forging process. In order to manufacture the cold forged product for the precision hub gear used as the ARD 370 system of bicycle, it examines the influences of different designs on the metal flow through experiments and FE-simulation. To find the combination of design parameters which minimize the damage value, the low gear length, upper gear length and inner diameter as design parameters are considered. An orthogonal fraction factorial experiment is employed to study the influence of each parameter on the objective function or characteristics. The optimal punch shape of fine tooth hub gear is designed using the results of FE-simulation and the artificial neural network. To verify the optimal punch shape, the experiments of the cold forging of the hub gear are executed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.769-772
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• 2005

This paper deals with the aspects of die design for the multistage fine tooth hub gear in the cold forging process. In order to manufacture the cold forged product fur the precision hub gear used as the ARD 370 system of bicycle, it examines the influences of different designs on the metal flow through experiments and FE-simulation. To find the combination of design parameters which minimize the damage value, the low gear length, upper gear length and inner diameter as design parameters are considered. An orthogonal fraction factorial experiment is employed to study the influence of each parameter on the objective function or characteristics. The optimal punch shape of fine tooth hub gear is designed using the results of FE-simulation and the artificial neural network. To verify the optimal punch shape, the experiments of the cold forging of the hub gear are executed.

• 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

• Transactions of Materials Processing
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• v.20 no.2
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• pp.154-159
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• 2011

The roll die forming (RDF) process is a new manufacturing technique for producing gear parts such as clutch drum and clutch hub in automotive transmission. In the RDF process, the material is deformed by a roll installed on a die set. Excellent productivity, low forming load and improved dimensional accuracy have quantitatively been shown to be the benefits of the RDF. In this study, the RDF process is applied to manufacture a clutch hub with a gear shaped part. A finite element (FE) analysis was performed in order to investigate the material strain field and dimension of the final product. Based on the result of the FE analysis, a RDF experiment was performed and the dimensional accuracy of the final product was validated. This work demonstrates that RDF is a process capable of producing a sound clutch hub.

• Transactions of Materials Processing
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• v.17 no.2
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• pp.124-129
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• 2008

Net shape forging technologies give many effects into the costs and qualities for the finished products. So, the studies to reduce the additional machining amount are very important in forging industry. Specially, there are two main topics in cold forging industry, such as, tool life and precision forging. In this study, new forging technique was proposed to eliminate the machining process for fixing up the length and improve the lead accuracy of gear. The luck-up hub is manufactured through many processes, such as upsetting, piercing and direct extrusion. The gear is formed in direct extrusion process; however, lead accuracy of the gear is over allowance limit. Therefore, the additional sizing process must be added. In this study, process design for closed-die forging of a lock-up hub used for a component of automobile transmission was made using three-dimensional finite element simulations, and the strain distributions and velocity distributions are investigated through the post processor. The rigid-plastic finite-element method for back pressure forging has been used in order to reduce development time and die cost. Using the FEM simulation, we found the optimum value of back pressure. The prototypes of lock-up hub parts were forged into the net-shape. In the experiment, lead precision of tooth are measured by the CCMM(Contact Coordinate Measuring Machine). The dimensional accuracy of forged part was improved up to the 40% when back press was applied.

• Tribology and Lubricants
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• v.29 no.6
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• pp.397-402
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• 2013

This study examined the tribological characteristics of the drive shaft and axle system in vehicles. The first drive shaft example contained end play for a CV joint that transferred part of the transmission power to the wheel. The joint part of the drive shaft was deformed because of reduced durability due to wear. Thus, vibrations caused the body to shake and become unbalanced when the drive shaft transferred the power. The second example was the cross-section of a shaft that connected the slip-connection of the propeller shaft on the input side to the yoke flange of the output side; the durability was reduced because of corrosion. End play caused by wear between the bearing and cross-section shaft appeared to cause shaking. In the third example, a grease leak reduced lubrication and thus caused damage to the hub bearing and inside the knuckle. The failure was produced by sticking. The fourth example had noise produced by the gear and gear transfer. This was due to the backlash of the pinion and few ring gears for the differential gear. Therefore, drive shaft and axle systems must be thoroughly checked and managed to minimize and reduce failure phenomena.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.393-400
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• 2014

In this study, an automatic transmission was developed for a bicycle. This transmission uses the pedal rpm and riding speed information for efficient riding. This transmission was installed on a bicycle using an internally geared hub. The automatic transmission was developed for a beginner to ride with proper gear changes. Indoor ride tests were performed to assess the performance of this transmission. Here, a 'beginner' is defined as a bicycle rider who can maintain a riding power of ~150W with a maximum heart rate of ~80%. Furthermore, 'ride with proper gear change' means that the rider could ride the bicycle while maintaining an efficient pedal rpm by the automatic transmission. One expert and four beginners participated in the ride test. The expert was chosen for the comparison with the beginners. To minimize environmental disturbances, the ride test was performed indoors. In this test, two types of gear changes manual and automatic were tested on two types of roads a road with a gradual incline of 0-3% and a road that simulates the bicycle road along the Han river in Seoul. The results of the ride tests show that the algorithm applied for the automatic transmission helps beginners to ride the bicycle efficiently.

• Journal of the Korean Society for Railway
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• v.11 no.2
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• pp.203-210
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• 2008

Since hub wheel BLDC Motor consisted of wheel and BLDCM (Brushless DC Motor) without gear reducer has high efficiency and low operation noise, it can be utilized to a driving wheel at some light rail systems. However, installing sensors for speedometer on a Hub-Wheel motor is not easy, so it requires a different speed control mechanism method for speed measurement. This paper introduces a speed control method based on simple mathematical model which uses discrete Kalman Filter to estimate and control the speed of the motor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.256-262
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• 2016

This study performed the back-pressure cold forging analysis to minimize the non-forming area of gear teeth for the output hub and reaction hub in automatic transmission. Two important factors of the back-pressure cold forging process, the load of the punch and the backup force applied to the sleeve, were determined through displacement control analysis. The non-forming area of the gear teeth was compared with both cases of the displacement control analysis and load control analysis, and their solution is similar to the measuring result of a real workpiece. The results show that the load of the punch is dependent on the reduction area of the workpiece, and the backup force applied to the sleeve is determined with regard to the cross-section-area of sleeve. This analysis procedure can be useful and effective in determining the manufacturing condition of the back-pressure cold forging process to minimize the non-forming area.