Papers by Keyword: Flexible Roll Forming

Abstract: In the present study, the technical feasibility of manufacturing a height-variable profile from an advanced high-strength steel (AHSS) sheet using the roll forming process was investigated through finite element analysis (FEA). The study focused on the production of a cross member used in a B-segment passenger vehicle. For this purpose, the kinematics of the forming rolls in both the height and longitudinal directions were derived and integrated into the finite element model. The sheet metal was modeled using both shell and solid (3D) elements. These two different modeling strategies were evaluated in terms of the formed profile geometry. The results demonstrated that the manufacturing of the selected cross member is feasible with the derived roll kinematics. Additionally, it was observed that the use of shell elements led to higher deviations from the desired geometry compared to solid elements. The analyses are planned to be validated experimentally in the next phase of the study.

Abstract: Flexible roll forming is an advanced sheet metal forming process which allows the production of variable cross-section profiles. In flexible roll forming process, nonuniform transversal distribution of the longitudinal strain can cause the longitudinal bow, which is deviation in height of the web over the length of the profile. To investigate the effect of flange length on the transversal distribution of the longitudinal strain, FEM simulations are conducted with different flange length for three blank shapes; trapezoid, convex and concave. The result shows that the longitudinal strain and longitudinal bow decrease with increasing flange length for a trapezoid and a concave blank. For a convex blank, the longitudinal strain and longitudinal bow increase with increasing flange length. To validate FEM simulation result, numerically obtained longitudinal strain has been compared with experimental results.

Abstract: Roll forming is a highly useful and important forming technique for sheet metal. As an economic profile product, roll forming products are widely used in transportation, engineering machinery, and civil construction because of their uniform sections, high strength, and low energy consumption^[1]. Roll forming is a rapid processing operation used for transforming flat sheets of material into useful profiled sections. However, a lot of components used in the automobile, railway cars, ship construction, and building industries have variable cross sections. Therefore, flexible roll forming was developed recently to produce variable cross section profiles.

Abstract: Focus on fracture defect of DP980 in Flexible roll forming, this research have done a finite-element analysis based on explicit solver and shear damage criterion, and using element deletion of finite element software ABAQUS to realize the fracture evolution of sheet damaged area. During the modeling, parameters of fracture evolution are set, and finally gain the conclusion about the relationship between stress, strain, energy density and fracture. The research provides theoretical guidance for practical production.

Abstract: An image mapping algorithm is proposed to improve the precision of flexible roll forming. The mapping algorithm based on visual feedback and Image analysis technology. On-line detection device realizes image acquisition of cross-section profile. After processing and analysis, geometric feature is extracted by Hough transform in the image. Geometric feature is transformed to matrix which is built a mapping relation with the original matrix. The mapping algorithm describes the displacement and rotary error in the process of flexible roll forming. Closed loop control is realized by feeding back the error to the control system. Experiments results show that the mapping algorithm is a good algorithm for on-line dimensional precision detection in sheet metal forming.

Abstract: Trip steel is broadly used in automobile manufacturing with its high strength and enhanced formability. For the variable section parts with protrusion and hole, roll forming is a kind of feasible way to realize continuous parts manufacturing, In the paper, with deep understanding of roll forming process and reasonable simplification, the FEM model of a multi-step variable section roll forming of 600MPa trip steel parts with protrusion and hole is established to analyze the mechanics and the deformation characteristics of the forming procedure. Equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained to guide the design of the variable section roll forming product line.

Abstract: For the flexible roll forming of the control system, this paper introduces a method that machine vision bind to the flexible roll forming control system. The detection method for sheet metal forming is image acquisition, image processing and other means for the extraction of sheet metal forming in some time section contour curve. Compare extraction section contour curve with the moment theory section contour curve in the control system, get the deviation value and feedback to the control system that interpolation arithmetic to realize closed loop control.

Abstract: How to manufacture high accuracy, complex section, high strength steel products is the current challenge of flexible roll forming technology. This article introduced opening NC system application in flexible roll forming, both in software and in hardware. As the core module of the software system, the interpolation module was discussed. The article mainly focused on how to establish track simulation module. According to the algorithm, we calculated the roller displacement and rotation angle using VC++. At last the simulation processes and results were presented, which prove the trace interpolation algorithm is correct and feasible.

Abstract: Due to the complex motion control in flexible roll forming when processing the sheet metal with variable cross-section, it is required for high real-time and high precision control during the processing. Controlling servo motor by adopting the configuration programming is a common approach to achieve roller motion, but it will not be able or difficult to realize by the configuration programming for complex contour sheet metal without the rules such as hyperbolic, or the molding product in non-symmetric cross-section shape, etc. Based on the process characteristic of flexible roll forming and its motion control technology, this paper adopts the variable time-domain discrete interpolation control method to process the variable cross-section sheet metal. Experiments indicate that this control method provides a good operating method for the sheet metal forming with complex variable cross-section shape in flexible roll forming.

Abstract: Flexible roll forming is a new forming process that produces parts with variable cross sections. This forming process is proposed to meet the need in the weight reduction of automobiles. With deep understanding of this process and reasonable simplification, the FEM model of a nine-step flexible roll forming of an ultra-high-strength steel bumper is established. In order to analyze the mechanics and the deformation characteristics of the flexible roll forming, equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained which can guide the design of the flexible roll forming product line.