• 한국정밀공학회지
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• 제12권11호
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• pp.118-124
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• 1995

In the paper, we have proposed a new technique to determine the initial billet for the forged products using a function approximation in neural network. A three-layer neural network is used and a back propagation algorithm is employed to train the network. An optimal billet which satisfied the forming limitation, minimum of incomplete filling in the die cavity, load and energy as well as more uniform distribution of effective strain, is determined by applying the ability of function approximation of the neural network. The amount of incomplete filling in the die, load and forming energy as well as effective strain are measured by the rigid-plastic finite element method. This new technique is applied to find the optimal billet size for the axisymmetric rib-web product in hot forging. This would reduce the number of finite element simulation for determining the optimal billet of forging products, further it is usefully adopted to physical modeling for the forging design

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.198-203
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• 1995

In the paper, we have proposed a new technique to detemine the initial billet for the forged products using a function approximation in neural network. A three-layer neural network is used and a back propagation algorithm is employed totrain the network. An optimal billet which satisfied the forming limitation, minimum of incomplete filling in the die cavity, load and energyas well as more uniform distribution of effective strain, is determined by applying the ability of function approximation of te neural network. The amount of incomplete filling in the die, load and forming energyas well as effective strain are measured by the rigid-plastic finite element method. The new technique is applied tofind the optimal billet size for the axisymmetric rib-web product in hot forging. This would reduce the number of finite element simulation for determing the optimal billet of forging products, further it is usefully adapted to physical modeling for the forging design.

• Journal of Advanced Marine Engineering and Technology
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• 제29권3호
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• pp.275-280
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• 2005

Recently there has been a growing interest in the design and manufacturing of the muffler tube due to the strict environment regulations, A muffler is an important part used to reduce noise and to purify exhaust gas in cars and heavy equipment. The shape of the muffler tube and the number of the tube hole has been made variously according to the weight and function of the car. The perforating technique of the muffler tube has a great influence on the manufacturing cost. In this study, metal forming analysis has been carried out to investigate the perforating process for the muffler tube and predict an optimal forming conditions of the muffler tube, Also its simulation results by the finite element method were reflected to the die design and the manufacturing system for the muffler tube. The perforating process is performed in the longitudinal direction of the tube. According to the simulation results, when the shear angle of punch was similar to the tube curvature, the optimal shape was obtained. Also when the clearance of die was 0.2mm, the burr was minimized and optimal shear section was obtained.

• 한국정밀공학회지
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• 제20권5호
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• pp.73-81
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• 2003

In case of hollow cylinder extrusion using porthole die, the effects of extrusion parameters-temperature, the speed of extrusion, the shape of the die and mandrel-on metal flow in porthole die extrusion of aluminum have been investigated. However, there have been few studies about condenser tube extruded by porthole die. Original metal flow of condenser tube by porthole die extrusion is similar to hollow cylinder extrusion but the estimation of metal flow for extrusion parameters is different. For example, variation of chamber length in hollow extrusion only affects the welding pressure, however, the welding chamber length in condenser tube extrusion influences to the welding pressure as well as the deflection of mandrel. This study was designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection according to angular variation in the bottom of chamber in porthole die. Estimation was carried out using finite element method in as non-steady state. Analytical results can provide useful information the optimal design of porthole die.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 춘계학술대회논문집
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• pp.40-43
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• 2000

A process optimal design methodology applicable to steady-state forming with a strain-hardening material is presented. in this approach the optimal design problem is formulated on the basis of a rigid-viscoplastic finite element process model and a derivative based approach is adopted as an optimization technique The process model the schemes for the evaluation of the design sensitivity considering the effect of strain-hardening and an iterative procedure for design optimization are described. the validity of the proposed approach is demonstrated through application to die shape optimal design in extrusion.

• 한국기계가공학회지
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• 제12권6호
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• pp.84-92
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• 2013

This study improves the formability in fine-blanking the lock plate of car seat belts using a low carbon steel(SM35C) plate. The optimal die design for the forming process is proposed using rules for process planning based on theories and field experiences. The optimal design is analyzed using commercial finite element software in order to solve the fracture problems in the extrusion process. Through the improved layout based on the FEM results, the fracture of the extruded part and the roll over problem are solved. Furthermore, it is demonstrated through the shown from experiments that the extruded part does not break in the modified die.

• 한국주조공학회지
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• 제20권2호
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• pp.97-103
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• 2000

In this study, a design of experiment, Taguchi method, was applied to optimize gating system design of escalator step die casting parts. Six shape factors which affect filling sequence of melt are adopted and divided into two levels respectively. Initial feeding differences of melt which were calculated by using S/N(signal-to-noise) ratio in each condition were demonstrated with the simulation of Flow-3D software program. Variations of S/N ratio according to shape factors were obtained and the optimal condition of gating system could also be obtained. It could be found that width of gate, contact angle of gate, thickness of runner are more effective factors on the filling sequence of melt than the others in this case of escalator step die casting parts. It showed that the economical gating system and sound filling sequence of melt were obtained by using Taguchi method.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 춘계학술대회논문집
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• pp.199-203
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• 2003

Idler of excavator are large product with diameter 500 - 600 mm and parts of a power transmit device. The object of the paper is developed large products by hot closed-die forging. The forging process which is proposed from numerical analysis and various tests is developed a large products with good quality. To estimate the design process parameters such as working load, temperature and flash thickness so on, numerical analysis are used by DEFORM 2D. To obtain a flow stress data and optimal forging temperature is carried out hot compression and tensile test at a various temperature range. Developed product is tested mechanical properties of elongation, hardness and tensile strength so on. Test results are presented excellent mechanical properties.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 International Symposium
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• pp.79-94
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• 2002

Root cause -Thermal expansion coefficient mismatch -Tape warpage -Initial die crack (die roughness) Guideline for failure prevention -Optimized tape/Substrate design for minimizing the warpage -Fine surface of die backside Root cause -Thermal expansion coefficient mismatch - Repetitive bending of a signal trace during TC cycle - Solder mask damage Guideline for failure prevention - Increase of trace width - Don't make signal trace passing the die edge - Proper material selection with thick substrate core Root cause -Thermal expansion coefficient mismatch -Creep deformation of solder joint(shear/normal) -Material degradation Guideline for failure Prevention -Increase of solder ball size -Proper selection of the PCB/Substrate thickness -Optimal design of the ball array -Solder mask opening type : NSMD -In some case, LGA type is better

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.231-234
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• 1998

This study presents steady-state finite element analysis of three-dimensional hot extrusion of sections through square dies. The objective of this study is to develop a steady-state finite element method for hot extrusion through square dies, and to provide theoretical basis for the optimal die design and process control in the extrusion technology. In the present work, steady-state assumption is applied to both analyses of deformation and temperature. The analysis of temperature distribution includes heat transfer. Convection like element is adopted for the heat transfer analysis between billet and container, and also billet and die. Distributions of temperature, effective strain rate, velocity and mean stress are discussed to design extrusion die effectively.