• 소성∙가공
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• 제17권8호
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• pp.649-656
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• 2008

Springback is one of factors affecting precision in metal forming. Its effect is particularly prominent in bending process. In this study, bending and forging process are used in order to manufacture a micro spring with two bending region from $60{\mu}m$ diameter wire. Springback in the process lowers the precision of the micro spring. Overbending for springback compensation has wide usage in a general way. However, this method requires repeated modifications of press dies until the tolerance is allowable, which causes that production cost and time increase. In this paper, we analyzed the mechanism of springback in the forming process of the micro spring using finite element method. In addition, a simple method to control springback without modifying dies was proposed by performing numerical analysis with various parameters.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.53-56
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• 2009

Roll forming process is one of important metal processing technology because the process is simple and economical. These days, roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate for productivity. However, it is difficult to apply to the forming of micro scale or sub-micro scale pattern. In this study, the roll forming processing for the micro scale is designed and analyzed. In this study, the forming of micro pattern for solar cell plate by incremental roll forming process is analyzed. The solar cell plate may have thousands of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll forming process. Also experiment is carried out process that is designed through simulation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 춘계학술대회 논문집
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• pp.56-59
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• 2009

Roll forming process is one of important metal processing technology because the process is simple and economical. These days, roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate for productivity. However, it is difficult to apply to the forming of micro scale or sub-micro scale pattern. In this study, the roll forming processing for the micro scale is designed and analyzed. In this study, the forming of micro pattern for solar cell plate by incremental roll forming process is analyzed. The solar cell plate may have thousands of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll forming process.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.379-382
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• 2007

The MEMS (Micro Electro Mechanical Systems) process is used in a micro/nano pattern manufacturing method. This method is based on the lithography technology. But the MEMS process has some problems such as complicated process, long processing time and high production costs. Many researchers are doing research in substitute manufacturing method to work out a solution to these problems. In this paper, we apply a dieless incremental forming technology to a substitute method of MEMS process. This dieless forming technology is using in the commercial scale sheet forming such as a prototype of automobile sheet parts. 5-axes CNC (Computerized Numeric Control) method are applied in this system to get a micro-scale dieless forming results. These 5-axes system are composed of precision AC servo motor stages (4-axes) and PZT actuator (1-axis). A PZT actuator is used in a precision actuating axis because it can be operated in the nano scale stroke resolution. This micro dieless incremental forming system has the advantage of minimization in manipulating distance and working space. As equipment and tools become smaller in size, minute inertia force and high natural frequency can be obtained. Therefore, high precision forming performance can be obtained. This allows the factory to quickly provide the customer with goods because the manufacturing system and process are reduced. To construct this micro manufacturing system, many technologies are necessary such as high stiffness frame, high precision actuating part, structural analysis, high precision tools and system control. To achieve the optimal forming quality, the micro dieless forming system is designed and made with high stiffness characteristic.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.209-212
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• 2001

It is known that the mim forming processes show somewhat different phenomena compared with the conventional metal forming processes, namely, the size effect, enhanced friction effect and etc. Such typical phenomena, however, are not predicted by the conventional finite element analysis, which has been an efficient numerical tool to predict the metal forming processes. It is due to the fact that the constitutive relations used does not describe the microstructural characteristics of the materials. In the present investigation, the finite element formulation using the rate-dependent rigid plastic crystal plasticity model of the face-centered cubic materials is conducted to predict the micro mechanical behaviors during the mim forming processes. The finite element analysis, however, provides mesh-dependent solutions for the intragranular deformations. Therefore, the couple stress energy is additionally introduced into the variational principle and formulated within the framework of the rigid plastic finite element method to obtain mesh-independent solutions. Micro deformations of single crystal and bicrystal with various orientations are calculated to show the potential of the developed formulation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 추계학술대회 논문집
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• pp.455-456
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• 2012

• 소성∙가공
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• 제11권5호
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• pp.439-446
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• 2002

This study presents a new computational model to analyze the grain deformation in a polycrystalline aggregate in a discrete manner and based directly in the underlying physical micro-mechanisms. When scaling down a metal forming process, the dimensions of the workpiece decrease but the microstructure of the workpiece remains the similar. Since the dimensions of the workpiece are very small, the microstructure especially the grain size will play an important role in micro forming, which is called size effects. As a result, specific characteristics have to be considered for the numerical analysis. The grains and grain boundary elements are introduced to model individual grains and grain boundary facets, respectively, to consider the size effects in the micro forming. The constitutive description of the grain elements accounts for the rigid-plastic and the grain boundary elements for visco-elastic relationships. The capability of the proposed approach is demonstrated through application of grain element and grain boundary element in the micro forming.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.715-716
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• 2007

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.165-166
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• 2010

• 소성∙가공
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• 제15권4호
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• pp.326-332
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• 2006

Sandwich structures, which are composed of a thick core between two faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Depending on the sheets by a rolling process, which is a more efficient and economical approach compared to other types of processes, has become an increasingly important subject of study. In this paper, we made a roll forming machine which progressive forming possible and force measurement for a roll forming of the sheet metal forming. And we designed a roll molding that arrayed of embossing size 3mm in diameter fabricate micro dimple inner structure plate. We carried out forming experiment such as array change and thickness to sts304 sheet. Ultimately, this research developed inner structure plate of high stiffness.