• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.173-176
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• 2007

The characteristics of the tool system give many effects into the costs and qualities for the finished components. This study proposes a new method for manufacturing of high manufacturing productivity, production process reduction and low cost through back pressure forming. The Lock-up hub is manufactured through many processes, such as upsetting($1^{st}$ Forming), piercing, direct extrusion($2^{nd}$ Forming), final sizing process($3^{rd}$ Forming). 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.

• 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.

• Journal of the Korean Institute of Gas
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• v.9 no.3 s.28
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• pp.44-48
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• 2005

Experimental works were carried out to evaluate the service life of low pressure LPG regulators for domestic use. Experimental results showed that the operating pressure of regulators used for 7 years notably deviated from the standard value of the adjusting pressure and the lock-up pressure. Thus, it is estimated that low pressure LPG regulators have approximately 6 years of service life.

• Tribology and Lubricants
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• v.21 no.3
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• pp.122-129
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• 2005

The floating ring seal has the ability of minimizing clearance without rubbing phenomenon. However, the seal ring can be unstable due to extremely high lock-up eccentricity ratio arisen from the poor design of height and surface finish of the ring. The exact prediction of the lock-up position of the floating ring is necessary to design the floating ring properly. The governing equations are developed and solved numerically. The test facility for the measurement of the boundary-lubrication-friction coefficient of the ring‘s surface has been established. Based on the results of analysis, the geometric conditions of the floating ring seal are suggested for operating at a low lock-up eccentricity ratio.

• Journal of Aerospace System Engineering
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• v.17 no.1
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• pp.10-15
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• 2023

Wet multi-disk clutch, a power switching device of the ducted fan, was optimized and results were analyzed. The clutch was divided into two types depending on whether a mechanical lock-up was applied or not. It was optimized under each design condition. Transfer torque capacity, friction material surface pressure, friction surface temperature, and drag torque were calculated as factors to optimize the clutch. The volume of separator plate and drag torque were used as the objective function for optimization. In the case of Type 1, which did not include a mechanical lock-up, the clutch could be operated regardless of the pitch angle of the ducted fan. However, the outer diameter of the friction surface was doubled, the volume was increased by 5~7 times, and the drag torque was increased by 7~12 times compared to those of Type 2, which included a mechanical lock-up.

• Journal of Energy Engineering
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• v.15 no.1 s.45
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• pp.23-27
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• 2006

This paper presents the evaluation of LPG (Liquefied petroleum gas) regulators for home use. For the evaluation, several properties of the regulators were experimentally analyzed, such as the operation of safety device, the adjusting and lock-up pressure, the adjusting spring and the diaphragm, with respect to the used time of the regulators. Experimental results showed that the initial operation performance of regulators were degraded with increase of the service time and also showed that the degradation of the performance and material property could become serious after six-year-use of the regulator.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1334-1339
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• 2003

An efficient method is developed for the shape optimization of 2-D structures. The sequential linear programming is used for minimization problems. Selected set of master nodes are employed as design variables and assigned to move towards the normal direction. After adapting the nodes on the design boundary, the B-spline curves and mesh smoothing schemes are used to maintain the finite element in good quality. Finally, a numerical implementation of optimum design of an automobile torque converter piston subjected to pressure and centrifugal loads is presented. The results shows additional weight up to 13% may be saved after the shape optimization.

• Tribology and Lubricants
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• v.19 no.6
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• pp.349-356
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• 2003

A damper floating ring seal with round hole pattern surfaces is suggested for better leakage control. The flat plate test of the round hole pattern surfaces has been performed to yield an empirical friction factor model. The exact predictions of the lock­up position of the damper floating ring, the leakage performance, and the rotordynamic coefficients of the seal are necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations including the empirical friction factor model for round hole pattern surfaces are solved by the Fast Fourier Transform method. The lock­up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the damper floating ring seal. Theoretical results show that the damper floating ring seals yield less leakage and better rotordynamic stability than the floating ring seal with a smooth surface.

• The KSFM Journal of Fluid Machinery
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• v.4 no.3 s.12
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• pp.29-38
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• 2001

The floating ring seal has the ability of minimizing clearance without the rubbing phenomenon. It is often used in the turbo pump units of liquid rocket engines due to its superior leakage performance. The exact prediction of the lock-up position of the floating ring, the leakage performance, and the rotordynamic coefficients of the seal is necessary to evaluate the rotordynamic performance of the turbo pump unit. The governing equations(which are based on the Bulk-flow Model) we solved by the Fast Fourier Transform method. The lock-up position, leakage flow rate, and rotordynamic coefficients are evaluated according to the geometric parameters of the floating ring seal.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.471-477
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• 2003

The floating ring seal is often used in the turbopump (TP) unit of liquid rocket engine (LRE) owing to its inherent ability of minimizing the leakage flow and superior dynamic characteristics as well. This paper describes the test results concerned with the lock-up and dynamic characteristics of the floating ring seals in the turbopump. The characteristics of the floating ring seals were extracted from the frequency response function (FRF) by instrumental variable method. The experiment was tested at 7.0MPa and 0-24,800 rpm. And the test results were introduced about the dynamic characteristics of floating ring seal related with the eccentricity and attitude angle.