• 한국기계가공학회지
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• 제9권5호
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• pp.28-33
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• 2010

A computer code was developed to simulate all three stages of the injection molding process: filling, packing and cooling by finite element method. The constitutive equation used here was compressible Leonov model. The PVT relationship was assumed to follow the Tait equation. The flow-induced birefringence was related to the calculated flow stresses through the linear stress-optical law. Based on the simulation, the Taguchi method was used to investigate the influences of injection molding conditions on the birefringence of a center gate disk. In addition, the optimal processing conditions were selected to minimize the birefringence and the birefringence difference along the positions of the disk.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.274-280
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• 1998

The welding technology and qualities are developed significantly, in recent years, in the use of automated processing technology and welding robot systems. But these automated welding technologies have many difficulties for finding the optimal welding parameter conditions. Because of the lack of mathematical model for determination of optimal welding process parameters. In this study, the sensitivity analysis of the empirical equations for finding weld bead width, height and penetration depth by using the published formulae. The selected major welding process parameters effected to weld bead geometries are the welding speed, current, voltage and weld wire diameter.

• 한국기계가공학회지
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• 제13권2호
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• pp.55-63
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• 2014

Fractures and wrinkles are two major defects frequently found in the sheet metal forming process. The process has several noise factors that cannot be ignored when determining the optimal process conditions. Therefore, without any countermeasures against noise, attempts to reduce defects through optimal design methods have often led to failure. In this study, a new and robust design methodology that can reduce the possibility of formation of fractures and wrinkles is presented using decision-making theory. A two-attribute value function is presented to form the design metric for the sheet metal forming process. A modified complex method is adopted to isolate the optimal robust design variables. One of the major limitations of the traditional robust design methodology, which is based on an orthogonal array experiment, is that the values of the optimal design variables have to coincide with one of the experimental levels. As this restriction is eliminated in the complex method, a better solution can be expected. The procedure of the proposed method is illustrated through a robust design of the sheet metal forming process of a side member of an automobile body.

• 한국생산제조학회지
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• 제21권2호
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• pp.349-353
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• 2012

As the world wind energy market grows rapidly, the productions of wind power generation equipment have recently increased, but manufacturers are not able meet this requirement. Particularly offshore wind energy industry is one of the most popular renewable energy sectors. To generalize welding processes, the welding automation is considered for steel structure manufacturing in offshore wind energy to get high quality and productivity. Welding technology in construction of the wind towers is depended on progress productivity. In addition, the life of wind tower structures should be considered by taking account of the natural weathering and the load it endures. The root passes are typically deposited using Gas Tungsten Arc Welding(GTAW) with a specialized backing gas shield. Not only the validation consists of welders experienced in determining the welding productivity of the baseline welding procedure, but also the standard testing required by the ASME section IX and API1104 codes, toughness testing was performed on the completed field welds. This paper presents the welding characteristics of the root-pass welding of high tensile steel in manufacturing of offshore wind tower. Based on the result from welding experiments, optimal welding conditions were selected after analyzing correlation between welding parameters(peak current, background current and wire feed rate) and back-bead geometry such as back-bead width(mm) and back-bead height performing root-pass welding experiment under various conditions. Furthermore, a response surface approach has been applied to provide an algorithm to predict an optimal welding quality.

• 한국공작기계학회논문집
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• 제15권1호
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• pp.113-118
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• 2006

In this work, we observed the changes in mass difference according to Al-foam's amount of Ca contents which depends on the viscosity control of fusion, quality of foamed addition, mixing, temperature tests. These are crucial influencing factors in determining foam-metal's size in the manufacturing process. In order to obtain the specimen, we changed the specific gravity from 0.2 to 0.3 for the study of the light weight, and obtained the optimal values of specific gravity, and then showed the mechanical characteristics of ultra-lightweight metal according to the changing mass. The optimal conditions for aluminum foam is when the addition of Ca content in $1.5wt\%~2.0wt\%$

• 한국생산제조학회지
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• 제21권4호
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• pp.593-600
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• 2012

Thixomolding of Mg-alloy is a semi-solid injection molding process utilizing thixotropic phenomenon. Using this process, higher strength, thinner wall section and tighter tolerance without porosity are obtained. It has been applied for production of near-net-shape magnesium component. To design optimal thixomolding process of Mg-alloy part, molding conditions such as slurry temperature, mold temperature and injection time should be determined properly. Selection of these parameters has been dependent upon engineers' experience and intuitiveness. In this paper, to improve mechanical properties of the thixomolded product, optimal selection of process variables such as injection velocity, barrel temperature and die temperature in the process has been studied through microstructural analysis and Taguchi method. Performance of the process is verified through experiments.

• 한국기계가공학회지
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• 제8권1호
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• pp.71-76
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• 2009

In a running blower, there are various exciting forces which can generate noise. The noise of an running industrial fan or blower depends on the structure of a fan, the machining accuracy of each element, and assembled conditions. Many studies have been carried out to reduce the noise of it. In this study, 3-hole buffs are used in pipe of blower to study the influence the number and position of buffs on the noise reduction at inlet and outlet in pipe. Commercial engineering software ANSYS and SYSNOISE were employed to analyze the characteristics and reduction ratio of pressure. It is concluded that optimal position and number of buffs in pipe of blower to show the least reduction ratio of pressure.

• 한국생산제조학회지
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• 제20권6호
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• pp.735-739
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• 2011

In this study, a chair with 5 or 6 legs was designed using the commercial program CATIA V5 in order to efficiently design considering the load conditions. In addition, the stress analysis and shape optimization were carried out using ANSYS Workbench for the chair consisting of stainless steel, aluminum alloys, magnesium alloys and structural steel. As a result, a chair with five legs showed the maximum equivalent stress at the end of the edge of the wheel parts and on the other hand, a chair with six legs showed the maximum equivalent stress at the corner of the connecting parts of the pillar and leg. In addition, the material and the weight was reduced by shape optimization for the chair model with 5 legs and maximum equivalent stress for stainless steel was found that greatly relaxed, compared with that of before shape optimization model.

• 한국생산제조학회지
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• 제20권3호
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• pp.232-238
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• 2011

In the present study, Taguchi method is used to determine the rough region first, followed by RSM technique to determine the exact optimum value during milling on a machining center. A region reducing algorithm is applied to narrow down the region of the Taguchi method for RSM. The result from the Taguchi method is fed to train the artificial neural network (ANN), whose optimum value is used to drive the region reducing algorithm. The proposed algorithm is tested under different cutting condition and results show that the introduced algorithm works well during milling process. It is also shown that theoretically obtained optimal cutting condition is very close to experimentally obtained result.

• Design & Manufacturing
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• 제18권3호
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• pp.9-14
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• 2024

Among the various plastic polymer molding methods, thermoplastic resins are most commonly used for mass production due to their suitability for high-volume manufacturing. However, recently, thermosetting resins have been utilized depending on product design and functionality, necessitating appropriate mold design and injection conditions to achieve suitable molded products. Therefore, resin selection must be considered not only in terms of product design but also based on functionality, taking into account the physical and mechanical properties of the resin. Additionally, since the flow characteristics of the resin are critical in injection molding, molding conditions should be set according to the thermal, physical, and rheological properties of the resin.This study focuses on the effects of filler content (glass fiber) in thermosetting fiber-reinforced plastics (FRP), specifically Bulk Molding Compound (BMC) resin, which is crucial for thermal deformation in automotive motor housing products. The resins used in this study include Generic BMC1 resin, BMC1 with 15% glass fiber, and BMC1 with 30% glass fiber. The research employs CAE (Computer-Aided Engineering) to investigate strain under basic conditions for the BMC resin and the strain variations with the addition of glass fiber. It also examines the impact of filler content on injection molding conditions, specifically mold temperature and curing time. Experimental results indicate that mold temperature has the most significant effect among the injection conditions, while the impact of curing time was relatively minor.