• Journal of Advanced Marine Engineering and Technology
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• v.26 no.4
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• pp.450-456
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• 2002

Die desig for manufacturing hooks from steel wires has been depended on empirical procedures based on trial and error method. To design die, at first the curvature and bending angle of hook are computed by using AutoCAD and developed program which is composed of Visual Basic. Then spring back should be considered because the elastic recovery of material is very important in bending process. In this study, bending analysis of elastic-plastic materials is applied to predict curvature of hook and spring back. Therefore, systematic procedure of die design for bending hook is achieved to consider elastic recovery in terms of hook shapes. Experimental results are good agreement with calculated results.

• Transactions of Materials Processing
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• v.8 no.6
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• pp.563-568
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• 1999

The study has been performed for the relation between die and product in closed die upsetting by the experiment. The strain of die has been given by the simple experiment using the strain gauge located at the outer surface of die and the deformation history of die and product has been given by the experiment and Lame's formula. The inner pressure of die causes the deformation of die that affects the accuracy of dimension and shape of product. The product with accurate dimension and shape can be obtained by analysing elastic deformation of die during upsetting process. The deformation of die during metal forming process has been usually predicted by the experience of industrial engineers or finite element analysis. But it is difficult to predict the dimension of product at unloading and ejected states. The study has given useful result for the deformation history of die and product through the experiment and Lame's formula at closed die upsetting, and can be applied in the die design for product with accurate dimension.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.76-79
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• 1999

The study has been performed for the relation between die and product in forward extrusion by the experiment. Strains of the die have been given by the simple experiment using the strain gauge located at the outer surface of the die and the history of the deformation of the die and product is given by the experiment and Lame's formula. The inner pressure of the die causes the deformation of die that affects the accuracy of dimension and shape of product. The product with accurate dimension and shape can be obtained by analysing elastic deformation of the die during process. The deformation of the die during metal forming process has been usually predicted by the experience of industrial engineer or finite element analysis. But it is difficult to predict the dimension of product at unloading and ejected states. The study has given useful results for the deformation history of the die and product through the experiment and Lame's formula at forward extrusion for solid cylinder and can be applied to the die design for product with accurate dimension.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.75-79
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• 2001

The study has been performed for the relation between die and product during forward extrusion by the experiment. Stains of the die have been given by the simple experiment using the strain gauge located at the outer surface of the die. The history of the deformation of the die and the product has been given by the experiment and Lame's formula. The inner pressure of the die causes the deformation of die that affects the accuracy of dimension as well as shape of the product. The product with accurate dimension and shape can be obtained by analysing elastic deformation of the die during the process. The deformation of the die during metal forming process has been usually predicted by the experience of industrial engineer or finite element analysis. But it is difficult to predict the dimension of the product at unloading and ejected states. In the present study, useful results for the deformation history of the die and the product were obtained through the experiment and Lame's formula in forward extrusion which can be applied to the die design for the product with accurate dimension.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.83-87
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• 2000

The die for cold forging gets a ver high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain a product with highly accurate dimension therefore it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between a die and a product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lames' formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion which can be applied in the die design for the product with accurate dimension

• Transactions of Materials Processing
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• v.13 no.5
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• pp.409-414
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• 2004

TRIP steel has got attention in automobile industry because of its high strength and high formability. However, the information on deformation behavior of TRIP steel, including bending and springback, is not enough until now. In this research, the V-die bending experiment and analysis have been done to obtain the information of springback of TRIP steel. And a new numerical method, where elastic modulus is varied with the change of the strain, was suggested. Tensile test for TRIP steel was done to get tensile properties as well as strain dependency of elastic modulus of the material. Strain-dependency of elastic modulus was used the numerical analysis of V-die bending and unbending process to predict springback amount. The results were compared with experiment, showing reasonable agreement. Through the analysis of V-die bending as well as draw bending of TRIP steel, the proposed scheme with variable elastic modulus was proven to well predict the deformation behavior of TRIP steel during bending and springback.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.29-37
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• 1995

In many metal forming processes, it is common to use stress rings for reducing elastic deformation and failures of forming dies. But, shrink fit of dies inner diameter of die insert, machining is reuqired after shrink fit processes. The reduction of inner diameter can be predicted by the analysis of elastic-plastic finite element method. The dimension of dies before shrink fit can be determined to minimize or remove machining after shrink fit processes by deformation analysis of die. The computation of contacting stresses along die surface was analyzied by rigid plasitic finite element method, and data were interpolated by the contact search algorithm. In this paper, we propose the analysis method of forging dies after shrink fit and forming to improve dimensional accuracy of final products.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.40-46
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• 2001

An integrated analysis for the thermo-elastic deformation, fatigue, wear and brittle damage evolution of the shrink-fitted die with multi stress-ring of dissimilar materials is presented. A simple numerical algorithm for the moving elastic boundaries characterizing the contacts of the insert and multi stress-rings is presented. The initial stress distribution in the die due to shrink-fit is considered and the traction at the die surface contacting with the work piece is obtained by analyzing the elasto-plastic deformation of work piece. Elastic analysis of the separate-type die is performed and then the evolution of brittle damage, wear and fatigue life are predicted. This integrated analysis is applied to the extrusion die with two layers of stress-rings and the results are discussed in detail.

• Transactions of Materials Processing
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• v.12 no.5
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• pp.498-503
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• 2003

The die for cold forging gets a very high axial load and radial pressure during processing and hence deforms considerably in the radial direction. This radial deformation of die becomes a important factor influencing the dimensional accuracy of a product. In order to obtain the product with highly accurate dimension, therefore, it is essential to acquire some information on elastic deformation of the die and the product. The study has been performed for the relation of the deformation between the die and the product in backward extrusion. The strain of the die has been given by the simple experiment using the strain gauges attached to the outer surface of the die. Also the history of the deformation of the die and the product has been given by the experiment and Lames' formula. The results has been compared with the previous another method. The study has given useful results for the deformation history of the die and the product through the experiment and Lame's formula in backward extrusion, which can be applied in the die design for the product with accurate dimension.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10b
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• pp.59-62
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• 2003

The precision cold forging of helical gear for steering pinion has been studied. Because of the large helix angle, there are many difficult problems to control the material flow and part dimension. The die shape was proposed to improve the flow of workpiece. In order to improve the dimensional accuracy of forged part, a FE analysis was performed. The proposed die shape drives to flow amicably workpiece. The applied load was reduced up to 10 percent, compared to the conventional-shaped-die. The elastic deformation of die has been investigated quantitatively by the 3-dimensional FE analysis. The die-land has been expanded up to $10{\mu}m$ on loading stage, based on the FEM results. Therefore, the elastic deformation amounts should be taken into consideration to improve the dimensional accuracy of forged helical gear.