• Transactions of Materials Processing
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• v.3 no.3
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• pp.359-374
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• 1994

Process sequence design in sheet metal forming process by the finite element method is investigated. The forming of sheet metal into a washing machine container is used to demonstrate the design of an improved process sequence which has fewer operations. The design procedure makes extensive use of the finite element method which has simulation capabilities of elastic-plastic modeling. A one-stage process to make an initial blank to the final product is simulated to obtain information on metal flow requirements. Loading simulation for a conventional method is also performed to evaluate the design criteria which are uniform thickness distribution around the finished part and maximum punch load within limit of available press capacity. The newly designed sequence has two forming operations and can achieve net-shape manufacturing, while the conventional process sequence has three forming operations. This specific case conventional process sequence has three forming operations. This specific case can be considered for application of the method and for development of the sequence design methodology in general.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.4
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• pp.77-87
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• 1994

This paper deals with an automated forming sequence design system by which designers can determine desirable operation sequences even if they have little experience in the design of cold forging process. The forming sequence design in the cold forging is very important and requires many kinds of technical and empirical knowledge. They system isproposed, which generates forming sequence plans for the multistage cold forging of axisymmtrical solid products. Since the process of metal forming can be considered as a transformation of geometry, treatment of the geometry of the product is a key in planning process. To recognize the geometry of the product section, section entity representation and primitive geometries were used. Section entity representation can be used for the calculation of maximum diameter, maximum height, and volume. 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 product geometry is expressed by a list of the priitive 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 proper sequence of operations for the part, is generated under the environment of AutoCAD. Based on the results of forming sequence, process variables(strain, punch pressure, die inner pressure, and forming load) are determined.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.200-205
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• 1993

The automatic forming sequence design system can determine desirable operation sequences even if they have little experience in the design of cold forging process. This system is proposed,which generates forming sequence plans for the multistage cold forging of zxisymmetrical solid products. Since the process of metal forming can be considered as a transformation of geometry, treatment of the geometry of the product is a key in planning processes. 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 product geometry is expressed by a list of the pnmitive 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 proper sequence of operations for the part, is generated under the environment of AutoCAD. The preliminary choice of some feasible forming sequences can verify by using the finite element simulation.

• Transactions of Materials Processing
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• v.4 no.1
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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.

• Transactions of Materials Processing
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• v.8 no.2
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• pp.160-168
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• 1999

This paper is concerned with the process sequence design of longneck flange forming by using cold extrusion with thick hollow pipe. The conventional hot forming process to produce a longneck flange is investigated by thermo-viscoplastic finite element method to observe the metal flow in detail and evaluate design requirements. Based on the results of simulation of the current hot forming process, design strategy for improving the process sequence are developed using the thick hollow pipe. The main goal is to obtain an appropriate improved process sequence which can produce the required product most economically without tensile cracking, workpiece buckling, and overloading of tools. Newly process condition such as semi-die angle, reductio ratio of cross-sectional area of axisymmetrical extrusion process. The final designed process can provide very useful guidelines to other flange forming industries.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.217-222
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• 1994

This paper describes the determination of optimal initial billet size for axisymmetric cold forging products using neural networks. The determination of optimal initial billet size is very important in forging design and forming sequence design, because the result of such designs and forming load can be different by variable initial billet sizes. The forming difficulty has been defined as the degree of difficulty in forming by 3 process ' forward extrusion, backward extrusion and upsetting. By neural networks a forming difficulty can be determined with the ratio of shape and forming process. From the graph of maximum, minimum, and average forming difficulties by variable billet sizes, the optimal billet size can be determined. The initial billets of a solid part and a hollow part whichwas determined by this study are compared with the sequence drawing generated by the one of forming sequence design system.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.10a
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• pp.30-36
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• 1995

Conventionally design for multi-stage cold forging depends on the designer's experience and decision-making. Due to such non-deterministic nature of the process sequence design, a flexible inference engine is needed for process design expert system. In this study, A* searching algorithm was introduced to arrive at the vetter process sequence design considering the number of forming stages and levels of effective strain, effective stress, and forming load during the porcess. In order to optimize the process sequence in producing the final part, cost function was defined and minimized using the proposed A* searching algorithm. For verification of the designed forming sequences, forming experiments and finite element analyses were carried out in the present investigation. The developed expert system using A* searching algorithm can produce a flexible design system based on changes in the number of forming stages and weights.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2234-2244
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• 1994

A process sequence of multi-operation cold forging for actual application in industry is designed with the rigid-plastic finite element method to form a constant velocity joint housing(CVJ housing). The material flow during the CVJ housing forming is axisymmetric until the final forging process for forming of ball grooves. This study treats the deformation as an axisymmetric case. The main objective of the process sequence design is to obtain preforms which satisfy the design criteria of near-net-shape product requiring less machining after forming. The process sequence design also investigates velocity distributions, effective strain distributions and forging loads, which are useful information in the real process design.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.4
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• pp.43-52
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• 1996

This paper describes interactive computer procedures for design the forming sequences in cold forging. This system is implemented on the personal computer and its environment is a commercial AutoCAD system. The programming language. AutoLISP, was used for the configuration of the system. Since the process of metal forming can be considered as a transformation of geometry, treatment of the geometry of the part is a key in process planning. To recognize the part section geometry, the section entity representation, the section coordinate-redius representation and the section primitive geometru were adopted. This system includes six major modules such as input module, forging design module, forming sequence design module, die design module, FEM verification module and output module which are used independently or in all. The sequence drawing wigh all dimensions, which includes the dimensional tolerances and the proper sequence of operations, can generate under the environment of AutoCAD. The acceptable forming sequences can be verified further, using the FE simulation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.4
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• pp.712-720
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• 1988

This paper describes some development of computer-aided system called "COLD-FORMING" and "DESIGN-DIE". "COLD-FORMING" is designed for the forming sequence and "DESIGN-DIE" for the die design of press forming rotationally symmetric parts. The computer program developed is used in interactive and written in BASIC. Design rules for process planning and die design are formulated from process limitations, plasticity theory and know-how of experience of the field. "COLD-FORMING" capabilities include (1) analysis of forming sequence and recognition of individual operation involved each step, (2) determination of intermediate shape and dimensions, (3) calculation of forming loads to perform each forming operation and (4) graphic out put for the operation sheet. "DESIGN-DIE" capabilities include (1) optimum die design corresponding to the output of "COLD-FORMING" and (2) graphic output for the die design.of "COLD-FORMING" and (2) graphic output for the die design.ie design.