• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.56-59
• /
• 2009

Roll forming process is one of important metal processing technology because the process is simple and economical. These days, roll forming process is tried to be employed in manufacturing the circuit board, barrier ribs and solar cell plate for productivity. However, it is difficult to apply to the forming of micro scale or sub-micro scale pattern. In this study, the roll forming processing for the micro scale is designed and analyzed. In this study, the forming of micro pattern for solar cell plate by incremental roll forming process is analyzed. The solar cell plate may have thousands of patterns, and the analysis of forming considering all the patterns is impossible due to the computational costs. In this study, analyses are carried out for various numbers of patterns and the results are compared. It is shown that the analyses results with four row patterns and twelve row patterns are same. So, it is considered that the analysis can be carried out for only four rows of pattern for the design of incremental roll forming process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1999.03b
• /
• pp.207-212
• /
• 1999

A computational method based on the three-dimensional finite element method is developed for the deformation analysis of roll forming process. the method approximates the process as a kinematically steady state deformation of strip. For industrial usefulness of the simulation method several rolls with arbitrary shapes in one stand can be considered. The shapes and the thickness distributions of strip after roll forming were examined by comparing computation results with experiments It is concluded that the tool is useful enough to predict the process. The overall simulation method was integrated into a sorftware package to help the industrial roll-design.

• Transactions of Materials Processing
• /
• v.20 no.2
• /
• pp.110-117
• /
• 2011

The purpose of this work is to develop of a press forming process for mobile phone battery cover as an alternative to the current manufacturing process by laser welding. This press forming process consists of a combination of bending, side pressing and side bending operations. The dimensional error for each process was investigated by finite element(FE) analysis and the Taguchi optimization method. The spreading of the cover width in the side pressing process was adjusted by modifying the blank shape with a notch. The over-bending method was adopted to compensate the spring-back which occurs after bending. Forming experiments were performed to verify the reliability of the developed press forming process. In addition, the strength of the product was evaluated to verify the suitability of the battery cover manufactured with this new press forming process. The results of the forming experiments indicate that the dimensional accuracy of the battery cover is within the required tolerance. The strength of the battery cover was evaluated to 547N which is larger than required strength of 400N.

• Transactions of Materials Processing
• /
• v.17 no.3
• /
• pp.218-224
• /
• 2008

A recent trend in automotive parts has been an integration of sub-assemblies with unified shapes. Tube structures also have been integrated to one body structure by using a near net shape forming instead of adopting welding. A cylindrical elastomer-forming process can be utilized to form a steel tube compressed in a radial direction. This process has some advantages compared to a hydro-forming or a swaging process in the viewpoint of a lower investment and a higher productivity. In order to predict a feasible specification of products within a work capability of the elastomer-forming equipment developed previously, effects of geometrical parameters of a tube on its shape accuracy are examined. Two characteristic parameters to account for the shape accuracy are chosen. One is the curvature radius at the corner part and the other is the straight ratio of the formed region. Careful examination of two parameters has led that the shape accuracy can be easily predicted by the regression equation obtained from the response surface method.

• Journal of the Korean Society for Precision Engineering
• /
• v.26 no.10
• /
• pp.89-96
• /
• 2009

In recent years, there has been a considerable interest in the application of super plastic forming in the aircraft and automotive industries. This requires a detailed design of the technological process in order to exploit its peculiar potentialities better. Nowadays, the finite element method is used to plan the sheet metal forming processes whose simulation requires determination of material constants for super plastic materials. The present work is aimed to show a simple method to characterize super plastic materials duplex stainless steel which was formed by a constant gaspressure to hemispheres with and without back pressure. The forming operation was performed using an in-house designed and built biaxial forming apparatus. The temporal change of dome heights of hemispheres were measured for applying the pressures. The flow stresses and strain rates developed at the top of the dome during the forming step were shown to follow closely the flow stress - strain rate relationship obtained from the strain rate change tests performed at the same temperature.

• Journal of Ocean Engineering and Technology
• /
• v.16 no.2
• /
• pp.38-43
• /
• 2002

Die-less forming is a cold forming process which is to bend thick flat plates into compound curved plates using two asymmetric rollers. This forming method has several advantages compared with line heating which is widely used to fabricate compound curved pieces in shipyards. The die-less forming, however, has scarcely been studied. Even the deformation mechanism in this forming process has not been understood clearly. So, in this paper, the deformation characteristics of die-less forming is investigated analytically and numerically. for the analytic investigation, slab method based on equilibrium equation is applied. And the mechanism of curvature generation is derived for the asymmetry in roller applied. And three dimensional numerical analyses are performed with realistic modeling of interactions between the rollers and work-piece using finite element program, ABAQUS. It is shown that curvature generation is mainly due to the difference of normal positive strain distribution between the top and bottom surface of the work-piece. And a convex-type curved plate is formed if the center region of the work-piece is rolled with asymmetric rollers of which the lower is larger than the upper in diameter.

• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.6
• /
• pp.419-427
• /
• 2018

In case high strength steels are applied for press-formed automotive parts, it is very difficult to secure forming accuracy due to large springback compared to moderate strength steels. In this study, a repetitive step-wise forming analyses based on secant method was proposed as the die design method for mandrel(bending tool) for the 2-axis bending equipments. A bending die with circular mandrel was designed for the DP780 blow motor case of which diameter and thickness are 70.8mm and 2.0mm respectively. Forming tests were performed to verify the validity of established die design and the results were compared with that of conventional HGI(Hot galvanized iron steel) blow motor case. For additional improvement in forming accuracy, an elliptical mandrel was proposed and its validity was verified using forming analyses based on secant method.

• Design & Manufacturing
• /
• v.18 no.2
• /
• pp.29-34
• /
• 2024

This study intends to reduce forming load by adding die rotation to flange-upsetting process. Materials arc formed by the compression and rotational torque which are accrued from rotation of the lower die accompanied by axial compression of the punch. For the theoretic analysis of flange-upsetting process using rotation die, slab method was used. Furthermore, for the verification of the theoretic analysis results, FEM simulation using DEFORM 3D a commercial software was done, and through the model material experiment using Prasticine, the results were compared and reviewed. Flange-upsetting process using rotation die shows reduced forming load compared with process without die rotation and demonstrates uniform distribution of strain. And as for the effect of the reduction of forming load, the less the aspect ratio(h₀/d₀) and the greater friction coefficient, the greater effect is. With increase in die rotation velocity, the effect of forming load reduction also increases little by little, but its effect on forming load reduction is very negligible compared with other forming parameters. Theoretic analysis results and simulation results coincided pretty well. The flange-upsetting process using die rotation are evaluated as useful process that can produce reduction of forming load and uniform strain.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.1 no.2
• /
• pp.21-26
• /
• 2000

Flow forming is a chipless metal forming method for axi-symmetric parts, which is more economical. efficient and versatile method of producing parts than the other sheet metal forming process such as stamping or deep drawing. In this study, flow forming process with 1-Roller is applied to produce auto-transmission parts of automobiles which have been produced by Press drawing process so far. It can be known that flow forming process is applicable to the flexible manufacturing system due to the low cost for the establishment and it can be combined with press forming process to promote productivity and to improve the accuracy of products.

• Fire Science and Engineering
• /
• v.21 no.1 s.65
• /
• pp.98-105
• /
• 2007

On this study, we verified the possibilities of making T-branch pipe forming with carbon steel pipes and stainless steel pipes used by common FEM Program(ABAQUS) which are widely used in the fire protection and building construction fields. In this kind of T-branch pipe forming works, in principle, the seamless pipe is used. If the pipe has the seam, the forming face must be the opposite side of the seam. The forming works are carried out by a truncated cone shaped plug. We found that the face slope and the length of plug are the most important factor in pipe forming. Based on the results of forming analyses, we proposed the minimum height and thickness of pipe branch forming.