• 소성∙가공
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• 제3권3호
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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.

• 소성∙가공
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• 제8권2호
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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.

• 소성∙가공
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• 제5권3호
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• pp.219-231
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• 1996

The current five-stage cold extrusion process to produce an axle-housing is investigated for the purpose of improved process. The main goal of this study is to obtain an appropriate reduced process sequence which can produce the required part most economically without tensile crack-ing workpiece buckling and overloading of the tools. The current process sequence is simulated and design criteria are examined. during the simulation several remeshings are done due to severe mesh distortions, Based on the results of simulations of the current five-stage process, design strategy for improving the process sequence are developed using the thick hollow pipes. The finished product of an axle-housing is produced in two operations and one annealing treatment while the conventional sequence consists of five operations and one annealing treat-ment. Also die loads of the new process are compared with those of the current one.

• 대한기계학회논문집
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• 제18권9호
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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.

• 한국정밀공학회지
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• 제17권6호
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• pp.127-134
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• 2000

The current three-stage cold farming process to produce a flange is investigated for the purpose of improvement of manufacturing process. The main goal of this study is to obtain an appropriate process sequence, which can produce the required part with less manufacturing cost. The current process sequence is simulated using finite element method and design criteria are examined. Based on the results of simulation of the current three-stage process. a design strategy for improving the process sequence is analyzed using the thick-walled pipes. Because it has a reduced process-sequence without buckling of the workpiece or overloading of tools, the new process has distinct advantages over the conventional process. Numerical results show that the newly proposed process with selected presses is the most economical way to produce the required part.

• 한국정밀공학회지
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• 제11권4호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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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.

• 대한기계학회논문집
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• 제18권8호
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• pp.2039-2052
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• 1994

In this study, an expert system for multi-stage cold forging process design of axisymmetric parts is developed. The available geometries are axisymmetric shape and cylinder with a hold in one end. The overall system is composed of knowledge-based system for process sequence design, output module interfaced with CAD system and material data-base. In the developed system, designed process can be modified in order to reduce the number of processes and make the distribution of forming load be almost equal at various deforming stages within the machine capacity. After process sequence design is completed, results can be stored as a text file or a commercial CAD system file. The capabilities of the developed system are illustrated through various examples of process design.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1995년도 추계학술대회논문집
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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.

• 소성∙가공
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• 제6권4호
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• pp.291-299
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• 1997

This paper is concerned with the design of process sequence to form the inner skin of landing gear. The inner skin of landing gear is a part of airplane which is known to be difficult to form its shape. Our study investigates the production method of inner skin and examines the design criteria by three dimensional elastic-plastic finite element method. Based on the results of simulation, design strategy for improving the process sequence is developed using stretch forming process. The final product of inner skin is produced in multi-stage operations with annealing treatment to meet the required capacity of press. The numerical results show that the newly designed process can produce the required part successfully within the design criteria.