• Transactions of Materials Processing
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• v.7 no.1
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• pp.12-22
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• 1998

An expert drawbead model is developed for the finite element analysis of stamping processes. The expert model calculates drawbead restraining forces and bead-exit thinnings with the forming condi-tions and drawbead size. The drawbead restraining forces and bead-exit thinnings of a circular draw-bead and stepped drawbead are computed by mathematical models and corrected by the multiple lin-ear regression method based on experimental measurements. The squared drawbead preventing the sheet from drawing-in inside die cavity is assumed to have a very huge drawbead restraining force and no pre-strain just after drawbead. The combined beads are considered as a combination of basic draw-beads such as circular a drawbead stepped drawbead and squared drawbead so that the drawbead restraining forces and bead-exit thinnigs are basically sum of those of basic drawbeads.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.402-405
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• 2005

Such press-forming process are the used machine ability and the characteristic, used material, tile accuracy of the part, condition of a process are considered the designed. In order to estimate in automotive sheet forming processes used AutoForm software. A through in simulation result comparison with experimentation result, it was possible to know that much the same estimated spring-back through a forming analysis. By making apply this to an industrial site the productivity improvement and cost reduction etc. effect able was predicted.

• Laser Solutions
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• v.5 no.2
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• pp.23-29
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• 2002

As automotive manufacturers have taken a growing more interest in tailored sheet metals for improving the rigidity, weight reduction, crash durability, and cost saving application of the tailored sheet metals to automotive bodies has been resently increased greatly. In this study, we investigated the characteristics of fatigue crack initiation behavior of laser welded sheet use for vehicle body panel. We experimented three types of specimens which were machined of the same base metal : one is 1.4㎜ thick, another is 1.6㎜ thick, the others is laser welded of the 1.4mm thick specimen and 1.6㎜ thick specimen. The results indicated that laser welded metal (1.4＋1.6㎜) is the best one for fatigue strength and fatigue life.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.180-188
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• 2000

Fine multi-hole sheet metal product(FMSMP) is a specific metal plate which is used in color TV and computer monitor. Processes of manufacturing FMSMP are generally composed of coating cleaning exposure and etching processes. After a thin metal plate is made by rolling photosensitive liquid is coated on the metal plate in coating process. Then the coated thin metal plate consecutively passes through exposure process in which upper and lower glasses are compressed by vacuuming the space between glasses and metal plate. In this lowered glasses are compressed by vacuuming the space between glasses and metal plate. In this lowered vacuum state certain part of metal plate is desirably exposed to light and will be etched into forming lots of well-arranged holes with a specific diameter, nowadays to manufacture FMSMP of 17 inch braun tube 80 second is required for complete vacuum but 35 second is applied to manufacture FMSMP in reality. In the present study vacuuming time is tried to reduce for improvement of productivity by analyzing vacuum system and proposing several solutions, for faster vacuuming speed degree of vacuum state between glasses and metal plate is improved by the proposed method and experiments using the proposed method are performed for verification. In addition microstructure of FMSMP is investigated to prevent stain phenomena and to improve quality of the product.

• Transactions of Materials Processing
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• v.25 no.5
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• pp.295-300
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• 2016

Recently, Ultra High Strength Steel (UHSS) sheet metal has been widely used to improve lightweight structures in the automobile industry. Because UHSS sheets have high strength but low elongation, it is difficult to control winkle and thinning for complex shaped products. The draw beads on die surface were introduced in this study to reduce wrinkle and thinning. The positions and strength values of draw beads were selected as design variables and optimized using finite element analysis. The beads positions and strength of a mold for B-pillar part were designed with the proposed optimization method. The accuracy of die design from optimization was verified by comparing with the results from 3-D scanned geometry.

• 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.

• Transactions of Materials Processing
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• v.18 no.1
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• pp.39-44
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• 2009

This paper is concerned with forming technology of an automotive front side member part with ultra high strength steel sheet of DP980. The forming technology considered in this paper is the draw & form type, which installs the upper pad and lower pad to produce the complicated shape of ultra high strength steel sheet. In order to produce sound product, comparison between form type and draw & form type and between draw type and draw & form type are investigated by FE-analysis. FE-analysis is carried out with commercial sheet metal forming analysis S/W, DYNAFORM. It was shown from FE-analysis that the draw & form type satisfied the required specifications such as the dimensional accuracy and soundness of automotive front side member part. The effectiveness of the analytical result was verified by the experiment. From this investigation, the draw & form type is proved to be able to supply useful forming technology in forming ultra high strength steel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1082-1086
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• 2004

Since the sheet forming of Mg alloy has many difficulties due to the low formability, many forming conditions need to be selected properly. Especially, the process variables should be investigated to increase the formability, such as, forming temperature. In this paper, the effects of forming process variables has been investigated using the bending and deep drawing process. A simple U-bending designed for mobile part could be formed in room temperature and springback amounts are surveyed. On the other hand, square cup part couldn't be formed in room temperature due to the low formability. Therefore, the effects of forming temperature are investigated in deep drawing process for square cup part. As a experimental and FEM results, the optimum forming temperature is presence and formability in a higher temperature is less than that of lower temperature. Above experimental results are compared with the FEM analysis and well coincided with the experimental results. Therefore, more detail investigations could be progressed to select more appropriate process conditions by the FEA.

• Design & Manufacturing
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• v.13 no.4
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• pp.17-22
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• 2019

Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.

• Design & Manufacturing
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• v.2 no.3
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• pp.40-44
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• 2008

Shaving in sheet metal forming is defined as a finish process to make the sheared surface clean which was blanked or pierced in the previous shearing stage. In this study the new shaving technique is applied to the progressive operation. The specimen is automatically fed by continuous movement of the strip. Which improve the positioning accuracy higher. For this study a square part which consist of blanking and piercing is selected for investigation and the progressive die which includes pre-piercing, pierce-shaving, half-blanking and blank-shaving etc is prepared for specimens of steel sheet(SPCC) and aluminum alloy sheet(AL5052). Experiments are carried out for several working variables such as shaving allowance, pre-shearing clearance and relative half-blanking depth. Consequently it was confirmed that the shaving by progressive die can be successfully employed to produce the clean parts requiring shaving process and optimum working conditions for shaving SPCC and AL5052 sheet metal are shaving allowance of 0.2mm(1.3% of thickness) and pre-shearing clearance of 5%.