• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.43-49
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• 2015

This paper describes the design of a forged fitting form to acquire a method of product design measurement by target measurement standards. The pipefitting connects each pipe and combines seals and nipples with the pipes normally. Therefore, the section combined with the fitting pipe was measured by a 3D scanner, and the acquired measurement and the design measurement were obtained after modification of the forged fitting pipe by that standard. Moreover, the accuracy of the model was verified through leakage testing of the oil and verification of the design measurement for accuracy decisions on the design measurement after modification of the product.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.92-97
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• 2007

A temporary structure is a framework of metal poles and planks, used as a working platform from which building repairs or construction can be carried out safety. The manufacturing process of the existing model consumes a many hour. So, it is modified manufacturing process. In this study, it is attempted to find out the shape of modified working platform considering manufacturing process and using Taguchi method, and it reduces production process. The design parameters are defined to discribe shape of model. As a result of the shape design, maximum Von-Mises stress and displacement considering a safety factor were satisfied with CTEA (Construction Temporary Equipment Association of Korea) standard.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.03a
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• pp.31-40
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• 1995

Powder metallurgy process has many advantages such as hight efficientyof material, mass productivity and complex shape production with good mechanical properties. Among the powder forming processes, incremental forging allows the consolidation to be achieved with amaller force then those required by conventional forging. In particular the proces known as rotary forging is an unique and prodominant process known as rotary forging is an unique and prodominant process in which the working constraints approximate to those in normal closed die forging. This study is concerned with the powder compaction by rotary forging process. An experimental rotary forging press with 500kN load capacity has been developed, which is equippe dwith the rotational conicla die inclined to the central axis of the press at arbitrary angle. It is found that the highly densified P/M parts can be obtained by rotary forging process and the material properties are superior to those of the conventrional sintered parts. The detailedcomparision of the mechanical properties by rotary forging process with those by conventional process are given.

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.81-84
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• 2001

This study introduces the new way for the evaluation criteria of the Mash-Seam Tailored Blank weldability, The materials used are low carbon automotive galvanized and high strength steels and the evaluation of weldability are examined with various thickness. Welding tests were conducted for both similar thickness and dissimilar thickness cases. The criteria developed for optimum welding conditions were based on the relationship among results of die press forming test, forming limit diagram, Erichsen test and microhardness measurements. The application of the developed criteria(fracture ratio, strength ratio, etc) in obtaining optimum welding condition revealed that a weld which satisfied ant of the criteria did not fracture during actual die press test and FLD dome test.

• Korean Journal of Metals and Materials
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• v.50 no.6
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• pp.433-438
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• 2012

Strength change in ultra low carbon steel carburized at $880^{\circ}C$ and $930^{\circ}C$ for 10, 30, 60 and 120 minutes was investigated. The results were analyzed by a tensile test, chemical composition analysis, optical microscopy and scanning electron microscopy. Stress in the 0.5% strain specimen in the tensile test increased as the time treated at $880^{\circ}C$ and $930^{\circ}C$ increased, because the carbon diffusion layer and the martensite of the specimen increased with increasing treatment time. Martensite was found in the ferrite region in the specimen treated at $880^{\circ}C$, which is attributed to grain boundary diffusion.

• Korean Journal of Metals and Materials
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• v.50 no.12
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• pp.883-889
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• 2012

Carbon diffusion of ultra low carbon steel treated at $880^{\circ}C$ and $930^{\circ}C$ for 10, 30, 60 and 120 minutes was investigated using optical microscopy, SAM, EPMA, and Micro Vickers. The martensite patterns of the specimens treated at $880^{\circ}C$ and $930^{\circ}C$ were different. Martensite in the ferrite region was found in the specimen treated at $880^{\circ}C$ because of grain boundary diffusion. Such phenomena is explained by a carbon diffusion model.

• Transactions of Materials Processing
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• v.25 no.1
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• pp.12-20
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• 2016

Press machines and dies are commonly used for 3D curved sheet forming. Using conventional die forming can cause economic problems since various modifications of the die shape are required depending on the product shape. Various types of flexible forming such as multi-point dieless forming (MDF), flexible incremental roll forming have been developed to improve the needed process flexibility. Although MDF can reduce the production cost using reconfigurable dies, it still has significant material loss. Drawbacks such as wrinkling, dimpling, and forming errors can also occur despite continuous investigations to mitigate these defects. A novel sheet forming process for 3D curved surfaces, a flexibly-reconfigurable roll forming (FRRF), has been recently proposed to overcome the economic and technical limitations of current practice. FRRF has no limitation on blank size in the longitudinal direction, and also minimizes or eliminates forming defects such as wrinkling and dimpling. Feasibility studies of FRRF have been conducted using FE simulations for multi-curved shapes and various sheet thicknesses. Therefore, the fabrication of a FRRF apparatus is required for any follow-up studies. In the current study, experiments with reconfigurable rollers were conducted using a simple design pre-FRRF apparatus prior to fabricating the full size FRRF apparatus. There are three candidates for the reconfigurable roller: a bar-type shaft, a flexible shaft, a ground flexible shaft. Among these candidates, the suitable reconfigurable roller for FRRF is determined through various forming tests.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.389-392
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• 2003

The deterioration of dimensional accuracy, caused by springback, is one of problems to always occur in sheet metal forming processes. As the demand for lighter and stronger metals increases, the development of improved forming processes settling the springback problem becomes more important. In this work, springback phenomena are investigated which occur in the press forming process with the anisotropic sheet metal and axisymmetric tools. The improvement possibility of dimensional accuracies, mainly, flatness, will be examined by applying blank holding forces as a method of springback control.

• Journal of Power System Engineering
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• v.6 no.3
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• pp.31-35
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• 2002

Brake tube is considered one of the most important parts in automobile. The shape of brake tube end has a great influence on the function of brake, and the quality and productivity of brake tube have relation to die design. The forming process of brake tube end is performed by hydraulic press forming machine. In this paper, the forming processes of tube end for automobile is analyzed and designed to make the optimal form of brake tube end. Also, finite element analysis has been carried out using $DEFORM^{TM}% 3D to predict the optimal shape of brake tube end and the results obtained showed the optimal length between punch and chuck is $1.0{\sim}1.2mm$. The shape of tube end is in good agreement with the finite element simulations and the experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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• pp.890-896
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• 2008

Sheet metal forming is one of the most useful and important method in manufacturing of the autobody panels because of the excellent production rate. The objectives of sheet metal forming processes are getting a desired geometrical shape of products with good quality, low cost and reasonable lead time. In this paper, we examined the validity of finite element method analysis on the automobile FRT-PLR-L/R stamping process by using the lancing engineering method. Lancing is a press operation in which a single-line cut or slit is made on part way across the strip stock, without removing any metal. As a result, it has shown that the proper lancing engineering method could prevent fracturing by improving sheet metal flow.