• 소성∙가공
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• 제9권5호
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• pp.504-511
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• 2000

Hydroforming is a forming process enabling circular metal tubes to be produced in complex cross sections along curved axial paths. This forming process is widely used to manufacture parts in automotive industry. This paper presents bending and forming results to following angle of weld line positions. These compare to good bending, bad bending and without weld line model case. And then this result of after forming compare to each forming cases. The purpose of this paper is found that adaptive weld line position for bended final shape.

• 한국정밀공학회지
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• 제30권7호
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• pp.733-740
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• 2013

The high-velocity electromagnetic forming (EMF) process is based on the Lorentz force and the energy of the magnetic field. The advantages of EMF include improved formability, wrinkle reduction, and non-contact forming. In this study, numerical simulations were conducted to determine the practical parameters for the EMF process. A 2-D axis-symmetric electromagnetic model was used, based on a spiral-type forming coil. In the numerical simulation, an RLC circuit was coupled to the spiral coil to measure various design parameters, such as the system input current and the electromagnetic force. The simulation results show that even though the input peak current levels were at the same level in each case, the forming condition varied due to differences in the frequency of the input current. Thus, the electromagnetic forming force was affected by the input current frequency, which in turn, determined the magnitude of the current density and the magnetic flux density.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2002년도 춘계학술대회 논문집
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• pp.125-128
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• 2002

The automotive industry have made an effort to reduce the weight of vehicle structures with increased safety, while initial model of the final product does not contain any prehistoric effects in a design stave. It takes lots of time to calculate forming effects that have great influences on the energy absorption of structures. In this paper, finite element inverse analysis is adopted to calculate forming effects, such as thickness variation and effective plastic strain as well as an initial blank shape with small amount of computation time. Crash analysis can be directly performed after inverse analysis of the forming process without remeshing scheme. The direct mesh mapping method is used to calculate an initial guess from the sliding constraint surface that is extracted from the die and punch set. Analysis results show that energy absorption of structures is increased with consideration of forming effects and finite element inverse analysis is usefully applicable to calculate forming erects of vehicle structures for the crash analysis.

• 소성∙가공
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• 제4권1호
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• pp.28-38
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• 1995

An integrated process planning system can determine desirable operation sequences even if they have little experience in the design of multistage cold forging process. This system is composed of seven major modules such as input module, pre-design module, formability check module, forming sequence design module, forming analysis module, FEM verification module, and output module which are used independently or in all. The forming sequence for the part can be determined by means of primitive geometries such as cylinder, cone, convex, and concave. By utilizing this geometrical characteristics(diameter, height, and radius), the part geometry is expressed by a list of the primitive geometries. Accordingly, the forming sequence design is formulated as the search problem which starts with a billet geometry and finishes with a given product one. Using the developed system, the sequence drawing with all dimensions, which includes the dimensional tolerances and the proper sequence of operations for parts, is generated under the environment of AutoCAD. Several forming sequences generated by the planning system can be checked by the forming analysis module. The acceptable forming sequences can be verified further, using FE simulation.

• 한국세라믹학회지
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• 제46권1호
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• pp.94-101
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• 2009

The physical properties of artificial aggregates made from clay and inorganic wastes with poor plasticity depends largely on forming method. The artificial aggregates composing of coal fly ash, stone sludge and clay were fabricated using 4 different forming methods and those physical properties were comparatively analyzed. The surface of aggregates made through the extrusion forming process was dense and smooth but was rough for the aggregates obtained by crushing a tile-shaped green body. The aggregates made by pelletizing process had a weak green strength and bumpy surface. The shell generated at surface during a high temperature sintering process induced the most aggregates to be bloated due to a dense shell. But the aggregates made through pelletizing process with dense surface layer showed no significant change in bulk density with sintering temperatures. The water absorption of aggregates decreased with sintering temperature, and that of pelletized specimen was standing $1.8{\sim}2.2$ times higher than that of made by other forming methods. It is concluded that the aggregates having various properties could be fabricated from one batch by using different forming methods.

• 한국기계가공학회지
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• 제17권4호
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• pp.143-149
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• 2018

A cable tray is a fixture to support and protect electrical and communication cables. In this study, a roll-forming analysis is conducted to produce an all-in-one cable tray. The number of process stands is calculated using an empirical formula. By applying bending methods to the design of the roll flower pattern, the final process stands and forming angles are determined. The shape and stress variations in the cable tray are modeled and observed by roll forming analysis using LS-DYNA Software. The width of the side rail and the maximum stress on all stands does not exceed the reference values. The forming machine and rolls are manufactured based on the results of the roll forming analysis. In addition, all-in-one cable trays satisfy the National Electrical Manufacturers Association standards when they are manufactured according to this design.

• 한국재료학회지
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• 제16권2호
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• pp.111-115
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• 2006

High-finned tubes have good thermal conductivity and have better cooling efficiency than plain tubes or low-fined tubes due to bigger air contact area. During high-fined tubes are manufactured by roll forming, the main technique is illustrated to optimizing primary material(copper pipe), optimized die matrix designing technique for roll forming, control manufacturing speed to develop productivity etc. In this study, a roll forming system was developed in oder to produce high-finned tube. Also a multi-step roll forming die was designed & built to produce high-finned tube that has over 10 mm fin height. And then, roll forming test using copper pipe was performed to produce high-finned tube. Roll forming process for producing highfinned tube was optimized by analyzing and adjusting misrostructure, hardness, and surface roughness of roll formed high-fined tube.

• 소성∙가공
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• 제9권1호
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• pp.35-42
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• 2000

In this paper, we developed the hydroforming simulator which can apply an axial compressive force and high internal pressure to bulge a tube. Experimental dtudies have been performed to investigate the effect of each parameters such as internal pressure and axial compression stroke required for the forming of circular components. Under the improper forming conditions there were two forming failures. One was the axial buckling due to excessive axial compressive load and the other was the circumferential necking fracture due to relatively high internal pressure. A safe forming zone without any failures exists between these two extreme zones. Also the condition of forming failure such as fracture is examined throughout the theoretical analysis. This paper covers a brief overview of the mechanism of hydroforming process as well as the design of die and tools.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.126-129
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• 2008

This paper concerns the progressive die design for an automotive bracket part aided by the computer simulation in order to eliminate the inferiority such as the crack. The computer simulation of the progressive forming process is utilized in order to investigate cause of the cracks. This paper proposes a new guideline for the die design which modifies intermediate shapes and adds intermediate forming stages in progressive forming process. The effectiveness of the proposed design is verified by the computer simulation. The simulation result shows that the modified die design for the progressive forming process can eliminate the crack and improve quality of the automotive bracket part.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.226-229
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• 2008

Hot press forming is an advanced forming technology fur manufacturing of complex and crash-resistant automotive parts using ultra high strength steels. The 3-dimensional FE analysis of hot press forming process, in which process the deformation, heat transfer and phase transformation behavior are fully coupled, is carried out. The vast amount of material properties for the FE analysis is obtained from material properties calculation software which is based on thermodynamic calculations. The overall methodology for the FE analysis of HPF process and the analysis results are discussed here.