• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.477-483
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• 2016

The spring-back and bow phenomenon in the roll forming process are important factors regarding the accuracy of evaluation of production goods. The purpose of this study was to determine the influence of spring-back and bow phenomenon according to the main variables (forming velocity and roll gap). The material of the forming sheet was high tension steel (SPFH 590), which has been used commonly in recent years. In order to accurately measure the spring-back and bow phenomenon, the forming sheet was formed into a V-shape. The study was applied to OFAT (One Factor at a Time) experimentation, with respect to the experimental variables (the forming speed and the roll gap). In the experimental results, the forming speed had a small influence on the spring-back and bow phenomenon. However, the roll gap had a greater influence on the springback and the bow phenomenon, as opposed to the forming speed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.357-360
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• 2008

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. In this process, each pair of forming rolls installed in a forming machine play a particular role in making up the required cross-section and longitudinal shape of the product. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal SILL SIDE manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle. And also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.42-49
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• 2016

This study was analyed V-bending in order to analyze the spring-back phenomenon in the roll forming process. The material of forming sheet used in the roll forming process is high tension steel and the product name of sheet material is POSTEN 60. The most important variable is the number of roll passes (3-Pass, 4-Pass, 5-Pass, 6-Pass and 10-Pass) and other roll forming process variables were fixed. To determine the characteristics of the tension and compression, the forming sheet was analyzed by dividing the layer (Upper and Bottom) in the thickness direction from the center line. The results of FEM simulation analysis was derived to von-mises stress equivalent strain, and the spring-back value was calculated according to the final forming shape. The more number of the roll pass, von-mises stress and equivalent strain value of forming sheet were lowed. Also, spring-back values tended to decrease. The results of this study can be utilized for prediction and trend of spring-back value in the roll forming process applied to high tension steel sheet. So, development time and cost of the roll forming process is expected to be reduced.

• Transactions of Materials Processing
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• v.23 no.6
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• pp.376-379
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• 2014

During roll forming a sheet metal is continuously and progressively formed into a product of the required cross-section and longitudinal shape. An example product is a circular tube with a required diameter, wall-thickness and straightness. Roll forming occurs by passing the sheet through a series of forming rolls that are arranged in tandem. Each pair of forming rolls in the roll forming line plays a particular role in obtaining the required cross-section and longitudinal shape in the product. In recent years, that process is often applied to car body parts by automotive industries. In the current study, an optimal model design and proper roll-pass sequences as well as the number of forming rolls and bending angles were used to produce a sill side. The effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.44-47
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• 2002

In order to make a doubly curved sheet metal effectively, a sheet metal forming process has been developed by adopting the flexibility of the incremental forming process and the principle of bending deformation which causes slight deformation to thickness. The developed process is an unconstrained forcing process with no holder. For this study, the experimental equipment is set up with the roll set which consists of two pairs of support rolls and one center roll. In the experiments using aluminum sheets and FEM simulation, it is found that the curvature of the formed sheet metal is determined by controlling the distance between supporting rolls in pairs and the forming depth of the center roll. The FEM simulation of the forming process using the roll set along the one path shows the distributions of the curvatures in two directions along the path, and gives information about the characteristics of the proposed forming process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1881-1888
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• 2003

This study show a numerical method to predict roll wear in the roll forming process. Archard's wear model was reformulated in an elemental form to predict volume of roll wear and then wear depth on the roll was calculated using the results of finite element analysis. Abrasive wear occurs at contact area in the roll forming process and the results of simulation are compared with experimental data in production line. The wear simulation approach with 3-D FEM program for roll forming process, SHAPE-RF is in good agreement with it in tendency.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.978-981
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• 2005

In order to manufacture a doubly curved sheet metal effectively, a flexible incremental roll forming process has been developed by adopting the advantages of the incremental forming process and the roll forming process by combining inherent flexibility of the incremental forming process and continuous deformation of the roll forming process. The forming method has been further enhanced to form general quadrilateral blanks (including a square, a rectangle, a symmetrical trapezoid and an asymmetrical trapezoid, etc.) into doubly curved shapes by controlling the forming paths developed by various experiments.

• Transactions of Materials Processing
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• v.17 no.1
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• pp.27-34
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• 2008

In order to manufacture a doubly curved sheet metal, the incremental roll forming process which adopts advantages such as the flexibility of the incremental forming process and continuous bending deformation of the roll forming process has been experimentally investigated. An experimental equipment was developed which was named as unit roll set (URS) consisting of two pairs of support rolls and an upper center roll. The upper roll equipped with the servo control unit is motor-driven and can be positioned in the vertical direction according to the user's commands. Four support rolls are idle, and they freely rotate only along the axis so as to transfer the plate more stably in the tangential direction of the rotation of the driving roll. In the process, the plate is deformed incrementally as deformation proceeds simultaneously in longitudinal and transverse directions. Through the experiments using URS, information regarding to forming schedules is found out to fabricate curved hull plates. This study demonstrates the further application of the incremental roll forming process in shipbuilding industries.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.310-313
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• 2007

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. In this process, each pair of forming rolls installed in a forming machine play a particular role in making up the required cross-section and longitudinal shape of the product. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal roll flower model and proper roll-pass sequence can be suggested by analyzing courcenter strain and longitudinal strain according to the roll-pass with FEM simulation. And also effects of the process parameters on the final shape formed by roll forming defects a evaluated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1213-1219
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• 2001

In this paper, modeling of the multi-pass roll forming process with the finite element method and defect prediction in roll forming process are presented. In the roll forming process, there occurs the defect of scratch. It appears on tubes because of the friction between the strip and the roll, the unexpected sliding velocity and the contact pressure when fabricating the tubes. The surface of the product will be not uniform due to the defect. The scratch can be predicted with the simulation modeling of the finite element method, and can be avoided by modifying the design.