• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.4
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• pp.93-99
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• 2019

A cross drilling/milling Unit is an important mechanical part which is widely used in many kinds of machining tool, and various gear trains with good accuracy and reliability features are widely used in power transmission systems. A study on a novel power transmission optimization method for driving gear trains in cross drilling/milling units is presented in this paper. A commercial program for gear system simulation, Romax Designer, was used in this research to intuitively observe the gear meshing and the load distribution conditions on the gear teeth. We obtained the optimal modification value through comparing the results of repeated experiments. For validation, optimized gears were fabricated and then measured with a precision tester.

• 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 Mechanical Science and Technology
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• v.14 no.9
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• pp.968-977
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• 2000

The motion of an aircraft landing gear over a rough runway can be modeled by a nonclassically damped system subject to nonstationary random excitations. In this paper, the approximate analysis methods based on either the real or complex normal modes for the computation of nonstationary response covariances are proposed. It has been found by simulation involving a realistic example that, for the nonclassically damped random vibrational systems, the approximate solution method based on the complex normal mode is superior to other approaches with respect to the accuracy and computation time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.1
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• pp.92-99
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• 2003

Bevel gears are important mechanical parts to transmit power in transportation system high precision parts like bevel gears might be manufactured by closed die forging process for dimensional accuracy. Closed die forging of bevel gears offers the high quality and good mechanical properties and also leads to considerable cost saving. To determinate the proper closed-die forging process for bevel gear forms, three-dimensional finite element simulation for the progressive forging process was earned out and also the simulation results were compared with experimental results.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.147-151
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• 2003

In the study, the modeling strategies in connection with the quantitative prediction and improvement of product accuracy and quality are proposed. The analysis models are composed of process chain, geometry of die, interface conditions between die and workpiece, material parameters, forming velocity of machine, and so on. A 3D simulation platform, around the software MSC. Superforge, is built up for the applications in net-shape forming parts. Some results for bevel gear are shown to demonstrate the efficiency of the modeling system.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.104-110
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• 2008

A lot of straight bevel gears have been manufactured by the cold forging process in order to improve the productivity and mechanical property of the product. The die for the cold forging of the gear needs high precision and reproducibility. In the study, cold forging die has been modeled by CAD/CAM and manufactured by machining center using ball end mill coated by (Al, Ti)N for heat-treated alloy steel(STD11, HRC 60). Through the measurement of the machined die, satisfactory dimensional accuracy and surface roughness were obtained. In the future, many 3-d cold forging dies will be directly machined instead of electric discharge machining.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.147-152
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• 2000

The ASF(Automatic Sheets Feeders) part of the printer has many bosses supporting gear-trains. Steel-pin bosses are substituted for plastic mold bosses because of advantages such as cost reduction, convenience of manufacturing and accuracy in dimension, but they have a weak point such as fatigue fracture due to low material strength, which causes a serious problem in the reliability of product. To prevent the fatigue fracture of bosses, we should exactly estimate the life to failure of the various shapes of bosses. We take the linear FEM analysis and the statistical method in this paper to figure out the life to failure of bosses. The maximum stress and life to failure of bosses can be easily estimated by this method. This paper specifies how to figure out the life to failure of bosses.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.10a
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• pp.169-174
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• 2000

This paper is about automatic design of measuring master gears. Master gears are usually thought of as gears of extreme accuracy level, but are better defined as gages to check the meshing action of production gears. This is usually not recognized because most mechanical gages are associated with static measurements rather than having the form of machine elements used in a functional check involving machine motion. In this paper the interface that allows beginners to design easily and quickly is provided. The addition and modification of data is easy and the reduced design lead time is feasible with the program even though users don't know much about program since it is developed with Visual Lisp and DCL.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.5
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• pp.24-33
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• 2003

This study proposed a technique for inverse problem, linear approximation of contact position and loading in single and double meshing of transmission contact element using 2-dimension model considered near the tooth by root stress. Determination of root stress is carried out far the gear tooth by finite element method and boundary element method. Boundary element discretization near contact point is carefully performed to keep high computational accuracy. The predicted results of boundary element method are good accordance with that of finite element method.

• 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.