• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.18-23
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• 1998

This paper describes a research work of developing a computer-aided design of blanking and piercing for irregular-shaped sheet metal products. An approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, production feasibility check, and strip layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend. material and thickness of product, complexities of blank geometry and punch profile, and availability of press. This system is capable of unfolding a formed sheet metal part to give flat pattern and automatically account for the adjustment of bend allowances to match tooling requirements by checking the dimensions and relationships of parts of the folded product. Also this system can carry out a process planning which is obtained from results of irregular shape of product that was successful in production feasibility check module according to flat pattern layout and generate strip layout drawing in graphic forms. The developed system provides its efficiency for flat pattern layout, and strip layout for the irregularly shaped sheet metal products.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.214-218
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• 1995

Much labor, an exceedingly long lead time, and the skills of experienced engineers are required for press tool design. To reduce such problems, several CAD systems for blanking or piercing have been developed. This paper describes a computer-aided design for blanking or piercing of irregularly shaped sheet metal products. An approach to the system is based on knowledge base rules. The process planning & die design system is designed by considering several factors, such as complexity of blank geometry, punch profile, and availability of press equipment and standard parts. Therefore, after checking a production feasibility for irregular shaped sheet metal products, this system which is implemented strip layout module can carry out a process planning and generate the strip layout in graphic forms. Also this system implemented die layout module can carry out a die design for each process which is obtained form the result of an automated process planning and generate parts and assembly drawing of a die set.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.46-50
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• 2000

The progressive die are multiple operations performed by means of a die having above two stages, on the each of stages performs a different operation as the sheet metal passes through the die hole. In the field of design and making tool for press working, the progressive die for sheet metal (STS 304, thickness : 0.5mm) is a specific division. In order to prevent the defects, the optimum design of the production part, strip layout, die design, die making and tryout etc. are necessary. They require analysis of many kinds of important factors, I. e. theory and practice of metal press working and its phenomena, die structure, machining condition for die making, die materials, heat treatment of die components, know-how and so on. In this study, we designed and constructed a progressive die of multi-stage and performed try out. Out of these processes the die development could be taken for advance. Especially the result of tryout and its analysis become the characteristics of this paper (part 1 and part 2) that nothing might be ever seen before such as this type of research method on all the processes. In the part 1 of this study we treated die design mostly.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.213-217
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• 2000

The progressive die are multiple operations performed by means of a die having above two stages, on the each of stages performs a different operation as the sheet metal passes through the die hole. In the field of design and making tool for press working, the progressive die for sheet metal (STS 304, thickness : 0.5mm) is a specific division. in order to prevent the defects, the optimum design of the production part, strip layout, die design, die making and tryout etc. are necessary. They require analysis of many kinds of important factors, i.e. theory and practice of metal press working and its phenomena, die structure, machining condition for die making, die materials, heat treatment of die components, know-how and so on. In this study, we designed and constructed a progressive die of multi-stage and performed try out. Out of these processes the die development could be taken for advance. Especially the result of tryout and its analysis become the characteristics of this paper (part 1 and part 2) that nothing might be ever seen before such as this type of research method on all the processes. In the part 1 of this study we treated die design mostly.

• Transactions of Materials Processing
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• v.7 no.6
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• pp.554-561
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• 1998

This paper describes a research work of developing a computer-aided design of lead frame semicon-ductor with piercing operation which is very precise for progressive working. An approach to the sys-tem is based on to knowledge-based rules. Knowledge for the system is formulated from plasticity theories experimental results and the empirical knowledge of field experts. This system has been writ-ten using AutoLISP to AutoCAD on a personal computer and is composed of three main modules which are input and shape treatment production feasibility check and strip-layout module. Based on the knowledge-based rules the system is designed by considering several factors such as material and thickness of product complexities of blank geometry and punch profile, and availability of press. Also strip-layout drawing generated by piercing operation according to punch profiles considered V-notch dimple. pad chamfer spank cavity punch camber and cross bow of lead frame is displayed in graphic forms. This system can be used by a novice who may not have any knowledge of tool design and will invrease efficiencies to the designer in this field.

• Corrosion Science and Technology
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• v.10 no.1
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• pp.1-5
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• 2011

The major purpose of the present study is to evaluate the performance of various galvanized (GI) or galvannealed (GA) mild steels and AHSS in stamping applications. Finite Element Analysis (FEA) of selected stamping operations was conducted to estimate the critical pressure boundary conditions that exist in practice. Using this information, laboratory tribotests, e.g. Twist Compression (TCT), Deep Drawing (DDT) and Strip Drawing (SDT) Tests, were developed to evaluate the performance of selected lubricants and die materials/coatings in forming galvanized steels of interest. The sheet materials investigated included mild steels and AHSS (e.g. DP600 GI/GA, DP780 GI/GA, TRIP780 GA and DP980 GI/GA). Experimental results showed that galvanized material resulted in more galling, while galvannealed material showed more powdering and flaking. The surface roughness and chemical composition of galvanized sheet materials affected the severity of galling under the same testing conditions, i.e. lubricants and die materials/coatings. The results of this study helped to determine the critical interface pressure that initiates lubricant failure and galling in stamping selected galvanized sheet materials. Thus, to prevent or postpone the critical interface conditions, the results of this study can be used to select the optimum combination of galvanized sheet, die material, die coating and lubricant for forming structural automotive components.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.591-594
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• 2000

This paper describes a research work of developing a computer-aided design of product with bending and piercing for progressive working. An approach to the system for progressive working is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of four main modules, which are input and shape treatment, flat pattern layout, strip layout and die layout module. Based on knowledge-based rules, the system is designed by considering several factors such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, bending sequence, and availability of press. Strip layout drawing generated by the piercing processes with punch profiles divided into for external area is simulated in 3-D graphic forms, including bending sequences for the product with piercing and bending. Results obtained using the modules enable the manufacturer for progressive working of electronic products to be more efficient in this field.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.22-32
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• 1998

This paper describes a research work of developing a computer-aided design of irregularly shaped-sheet metal product with bending and piercing operation for progressive working. An approach to the CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of five main modules, which are input and shape treatment, flat pattern-layout, production feasibility check, blank-layout, and strip-layout module. Based on knowledge-based rules, the system is designed by considering several factors, such as radius and angle of bend, material and thickness of product, complexities of blank geometry and punch profile, and availability of press. This system is capable of unfolding a formed sheet metal part to give flat pattern and automatically account for the adjustment of bend allowances to match tooling requirements by checking dimensions and the best utilization ratio of blank-layout within bending production feasibility area which is beyond ${\pm}30^{\circ}$ degrees intersecting angle between grain flow and bending edge line and which is suitable to progressive bending operation. Also the strip-layout drawing generated by a bending and a piercing operation according to punch profiles divided into automatically for external area of irregularly shaped-sheet metal product is displayed in graphic forms.

• Design & Manufacturing
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• v.12 no.1
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• pp.13-17
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• 2018

It was analyzed and experimented on the change of the material thickness according to the size of the "R" of the punch and die corners using the material of SCP-1 0.25mm As a result, the following conclusions were obtained. Tensile strength analysis and safety analysis of materials are very important process for each process in strip layout, and Through this, the Influx of material and the deformation of the material were found. As a result of safety analysis and tensile thickness analysis, when the corner R of the punch was 0.3 mm and the edge R of the die was 1.0 mm The inflow of the material was not smooth, and the thickness of the corner part became 0.2 mm, causing cracks. when the corner R of the punch was 0.5 mm and the edge R of the die was 1.5 mm The inflow of the material was smooth, The thickness of the corners of the product is 0.21mm and It was considered that cracks do not occur when the thickness of the bottom surface and the body part becomes thin. The results obtained by applying the results obtained from the analysis, In Experimental Condition 1, a crack occurred in the same part of the analysis In Experimental Condition 2, the flow of the material was smooth and the drawing processing could be performed without generating cracks.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2165-2172
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• 1995

Optimization of mesh discretization has been proposed to improve the accuracy of limit analysis solution of collapse load by using the Rigid Body Spring Model(R. B. S. M) under the plane strain condition. Moreover, the fracture behaviour of materials was investigated by employing the fracture mechanism of a spring connecting the triangular rigid body element. It has been clarified that the collapse load and the geometry of slip boundary for optimized mesh discretization were close to those of the slip line solution. Further, the wedge-shaped fracture of a cylinder under a lateral load and the central fracture of a strip in the drawing process were well simulated.