• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.131-135
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• 2003

The form-joining process (or clinching) uses a set of die and punch to impose the plastic deformation-induced geometric constraint on a sheet metal pair, But their joining strength ranges 50-70 percent of that of the resistance spot welding. In this paper, a new form-joining process with the aid of adhesive is proposed in which an epoxy adhesive is applied to a sheet metal pair, to improve joining strength. The strength and mechanical properties of the new process are discussed and compared for other joining processes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.389-392
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• 2003

The deterioration of dimensional accuracy, caused by springback, is one of problems to always occur in sheet metal forming processes. As the demand for lighter and stronger metals increases, the development of improved forming processes settling the springback problem becomes more important. In this work, springback phenomena are investigated which occur in the press forming process with the anisotropic sheet metal and axisymmetric tools. The improvement possibility of dimensional accuracies, mainly, flatness, will be examined by applying blank holding forces as a method of springback control.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.381-385
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• 2007

In order to examine the effect of the blank holding force on the friction behavior in the sheet metal forming, a sheet metal friction tester is designed and manufactured, which can measure friction forces in various forming conditions such as lubrication, die roughness, drawing speed, radius of die corner, blank holding force, etc., and the friction tests are performed, in which friction coefficients in various blank holding forces and pulling speeds are calculated using Coulomb's friction law. The friction test reveals that friction coefficient decreases as the blank holding force, the drawing speed and lubricant viscosity increase together or individually.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.400-404
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• 1997

This paper presents spatial relationshaps and engineering features for the feature based modeling of Sheet Metal Weld Assemblies (SMWA) that are made of sheet metal components through are welding processes. Spatial relationships in ProMod-S, a sheet metal product modeler,are further extended for the SMWA modeling. Some spatial relationships for special weld joint types are newly introduced. The geometrical and topological relations between spatial reationship, mating features, and assembly features are defined. Finally, assembly data stucturess for the product modeling of SMWA are proposed. They are an engineering relation to represent the constraints between component features, and a mating bond to integrate component design information.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.5
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• pp.50-58
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• 1998

A proper model of expert system for the very thin sheet metal press die design has been suggested. Using the suggested model, an expert system of the very thin sheet metal press die has been developed. This study contains that the results from the developed system for three kinds of specimens have the adaptability in the actual site. In addition, the possibility for expansion of this system has been discussed. The developed system, which is based on the knowledge base, has been included in a lot of expert's technology in the practice field. C-language under the HP-UNIX system and CIS customer language of the EXCESS CAD/CAM system have been used as the overall CAD environment. Results from this system will provide effective aids to the designer in this field.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.2
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• pp.125-136
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• 2012

Wrinkle and fracture are two major defects frequently found in the sheet metal forming process. In this process there are more than one design attributes to optimize and several uncontrollable factors which cannot be ignored in determining the optimal values of design variables. Therefore, attempts to reduce defects through a traditional optimization technique are often led to failures. In this research, a new design method for reducing the wrinkle and fracture under uncontrollable factors is presented by using decision-making theory. To avoid the psychological difficulties in determining the scaling constants of the multi-attribute utility function by using the ordinary lottery questions, a pair-wise comparison procedure is adapted to avoid this problem. The effectiveness of the proposed method is illustrated through a robust design of sheet metal forming process of a side member of an automotive body.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.10a
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• pp.24-27
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• 1997

In the present work, rigid-plastic continuum elements employing the shape change and anisotropic effects are derived for the purpose of applying more realistic blankholding force condition in three-dimensional finite element analysis of sheet metal forming process. In order to incorporate the effect of shape change effectively in the derivation of finite element equation using continuum element for sheet metal forming, the convected coordinate system is introduced, rendering the analysis more rigorous and accurate. The formulation is extended to cover the orthotropic material using Hill's quadratic yield function. For the purpose of applying more realistic blankholding force condition, distributed normal and associated frictional tangent forces are employed in the blankholder, which is pressed normal and associated frictional tangent forces are employed in the blankholder, which is pressed against the flange until the resultant contact force with the blank reaches the prescribed value. As an example of sheet metal forming process coupling the effect of planar anisotropy and that of blankholding boundary condition, circular cup deep drawing has been analyzed considering both effects together.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.28-31
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• 2001

Friction for sheet metal forming affects improvement of deep drawing formability. The deep drawing is affected by many process variables, such as lubricant, blank shapes, shape radius and so on. Especially, lubrication is very important formability factor. In this study, in order to investigate fraction coefficient of sheet metal forming, we examined friction test about three conditions, such as non-lubrication, full lubrication and film lubrication. We measured friction coefficient according to pin load under the conditions like deep drawing die. Mean friction coefficient for film lubrication condition would be very useful value to improve drawability.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09c
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• pp.49-54
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• 2010

In order to study the performance of levees reinforced with steel sheet piles under high water condition, a series of model tests was conducted by simulating the high water condition before and after applying severe seismic loading history. As a result, the seepage behavior through the subsoil layers underlying the levee was not significantly affected by the seismic loading history. It was also verified that, irrespective of the seismic loading history, the sheet piles installed at the levee crest or shoulder are effective in preventing the breakage of levees caused by overflow. In addition, applicability of drainage works at the foot of the levee in preventing the seepage failure was confirmed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1107-1118
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• 2001

The forming limit diagram introduced by Keeler and Goodwin has been used generally to analyze the formability of sheet metal. However, path dependent forming limit curves based on the state of strain can be explained only by a single criterion which is based on the state. In this study, experimental forming limits in strain space of some metal sheets are transformed into forming limit curves in stress space. Effects of yield criterion are investigated in transforming the forming limit curves. Some important design aspects which are based on the close prediction of movements in forming limit curves during sheet forming are concluded.