Papers by Keyword: Roll Forming

Abstract: Roll forming pipes for hydrogen infrastructure poses particular challenges for process design, especially with regard to geometric accuracy and the avoidance of forming defects that could compromise the integrity of the pipelines. Geometric accuracy is crucial to ensure uniform pressure distribution within the pipe. Conventional trial-and-error approaches to developing roll flower designs are time-consuming and cost-intensive, especially when working with high-strength steel grades. This work presents an integrated methodology for roll forming of monolithic sheet by incorporating real-world machine stiffness and experimental anisotropy. A finite element model was developed for S235 and S355 steels, validated through three-point bending and Digital Image Correlation (DIC). While database-derived models (JMatPro) underestimated yield stress by up to 30%, the experimental model precisely predicted strain distributions (error < 2%). A central novelty is the integration of in-situ 3D laser scans of the roll forming mill under load, allowing the simulation to account for elastic machine deflection. This enables the prediction of process-induced residual stresses, which are critical for the long-term integrity of pipelines against hydrogen-induced cracking.

Abstract: Thick-walled longitudinally arc-welded tubes are indispensable in modern infrastructure owing to their exceptional load-bearing capacity and structural integrity. Nevertheless, their fabrication remains highly challenging, as the conventional forming forces demand the use of large-scale industrial presses. To address this limitation, this research introduces a novel process architecture that integrates agile tube roll forming process for tube manufacturing, thereby enabling the production of such tubes using significantly smaller and more flexible manufacturing systems. To this end, three tube support configurations—namely, support-less, dynamic roller support, and static support—were systematically investigated in this study on 7, 9, 11, and 15 mm thick 304 stainless steel. While the supportless condition represents the most economical option, the incorporation of dynamic or static support significantly improves geometric accuracy, yielding near-net cross-sections combined with reductions in tube ovality of approximately 75 and 79 %, respectively, compared to support-less configuration. Considering the straightness of the weld line as a quality indice, the dynamic support provides the highest quality. Using the static/dynamic support strategies, the deformation forces arise between 2 and 3 times compared to support-less strategy.

Abstract: High-strength aluminum alloys, such as the AA7075 alloy, offer great potential for lightweight construction thanks to their high specific strength. However, high strength and low ductility are a challenge for processing these materials. In our study, three different process routes (T6, W-Temper, O) for roll forming of a hat profile are investigated experimentally and in an FE-simulation. Since the targeted production of the hat profile is hindered due to material failure in T6-condition, inline induction heating and subsequent water spray quenching is used to bring the material to the W-Temper state before roll forming. As a third option, a pre heat treatment is applied to a soft annealed (O) material state. The experimental results show fundamental differences of the forming processes, depending on the tempering condition. The FE-simulation involves the roll forming process for the production of a hat profile and shows a high agreement with the experiments. Finally, the experimental results demonstrate how inline solution annealing by induction heating for the W-Temper process affects the properties and the quality of the profiles produced.

Abstract: During the bending operation of the thin sheet materials by the punch with the near-to-zero radius the special technological operation should be carried out. It means that the metal sheet obtained a certain thinning value, which is usually done in the form of the channel-concentrator or groove by pre-drawing operation in a cold state. It follows to the pre-straining and strengthening of the material. The authors investigated the strain hardened sheet's area after roll forming process theoretically, and obtained the strain-stress distribution inside the sheet during the bending operation. It was found out that the increase of the prior deformation during pre-straining in the bend layer follows to the increase of the radial and tangential stresses and displacement of the neutral axis inside the blank during bending operation. As a result, the bending moment changes its values depends on the punch radius and strain hardening.

Abstract: Roll forming has been widely used to produce steel sheet with low formability such as Ultra High Strength Steel (UHSS). It allows the steel sheet to be formed through successive bending process into a desired shape which even cannot be formed by press brake forming. Although the process effectively improves the formability of UHSS, there still the remains accuracy issue such as springback, flair, bow and so on. Especially, springback of UHSS is one of the major challenges in roll forming process as much as press forming process. In this paper, the springback of 1.5 GPa grade steel in roll forming process was numerically investigated for automotive sill-side inner component. The material behavior was described by using the selected hardening models: isotropic hardening (Piecewise linear model), linear kinematic hardening (Prager model [6]), nonlinear kinematic hardening model (Yoshida-Uemori model [7]). A commercial software LS-DYNA was utilized for the analysis. Eighteen successive roll stages were modelled for the simulation. From the results, it was found that the springback prediction during roll forming process could be successfully achieved when the complicated material behaviors including Bauschinger effect, nonlinear transient hardening, and changeable unloading modulus are taken into account for the Finite Element (FE) simulation.

Abstract: Because of relative low investment cost on the installation of equipment and extensive product quality with other advantages, roll forming process has been broadly applied to produce profiles from steel strip bands and has gradually replaced aluminum profiles made by hot extrusion. Moreover, a lightweight design is the trend for reducing carbon emissions and waste. Therefore, a lightweight design of structures with local thinning used the roll forming production will make metal profiles more market competitiveness. In this study, the commercial Finite Element software DEFORM is used to investigate the rolling process preparing the metal strips with local thinning feature for the subsequent roll forming process to form a lightweight metal profile. Two kinds of roll configuration are used in this study, namely symmetrical and non-symmetrical. The symmetrical rolling process has the same diameter for the upper and the lower roll, while the non-symmetrical rolling process has different diameter in both rolls. As the process parameters, the roll speed ratio between the upper and the lower roll is used for the symmetrical rolling process, while the distance between the axis of the upper and lower roll is used for the non-symmetrical rolling process. As a result, the rolled thinning feature has its sidewalls flaring outwards, so that it has a narrow bottom and a wide opening. Furthermore, it can be regarded as defect that the thickness of the rolled thinning feature is not thinned enough as required and a raising at the opening is observed. In general, increasing the roll diameter or keeping the speed of the two rolls as the same can have a better thinning result for the symmetric rolling. In the non-symmetric rolling, increasing the roll diameter can improve the thickness, but no significant effect can be found by changing the roll diameter ratio.

Abstract: Heat-resistant alloys are the basic material of gas turbine engine (GTE) design. Fine-grained structure in these alloys can be formed by isothermal forging and then different axisymmetric GTE components as wheels, shafts, rings can be superplastic roll formed. Examples of the superplastic and isothermal deformation use for manufacturing components out of superalloys and steels for critical applications are given. The possibility of roll forming parts as rings with a diameter up to 800 mm and as flange - cone with a diameter up to 600 mm out of superalloys (Inconel 718, EK79, EP741NP), accordingly, on SRZHD-800 and modified PNC-600 mills were showed. The macrostructure investigations of the components after the roll forming showed that the homogeneous structure was formed. The microstructure at the flange portion was fine-grained and at membrane zone was coarse-grained. Cone part was roll formed at isothermal condition from pre-stamped chromium martensitic steel sheet. Manufacturing technology of roll forming was tested by computer and physical simulation. Service properties of components were obtained by subsequent heat treatment. The effectiveness of the technology associated with increased service properties of components and decreases the labor content by automated equipment.

Abstract: Roll forming has been widely used to manufacture constant cross-section products because of high quality, efficiency and low cost. It is quite epidemic in producing automobile parts made of advanced high strength steels (AHSS) nowadays. However, with the development of the vehicle industry and diversity of the products, variable cross-section profiles have attracted more and more attention. The traditional roll forming technique is difficult to meet the requirements. Chain-die forming which was introduced in recent years makes it possible. Chain-die forming is an extension of roll forming and its key characteristic is enlarging the rotation radii of the moulds, by which the deformation zone is extended. The study focused on the finite element simulations of Chain-die forming U profiles with variable cross-section, including variable width and height. The feasibility of Chain-die forming producing variable cross-section products was verified by the perfect simulation results. The advantage of Chain-die forming was that there was no need to design the intermediate moulds except the finished-profile ones, which reduced the mould quantity immensely. Then the cost was lower.

Abstract: Roll forming is a kind of plastic forming process in which a steel strip is bent by several sets of rolls gradually into the desired shape. The products are cold roll forming steels with various sections. Roll forming is one of the most widely used processes in the world for forming metal. Roll forming is a complex deformation process, which involves large displacement, finite strain and the problems of contact and friction between strip and rolls. This process exhibits obvious geometry, physical and boundary nonliterary. The complex processes contain many aspects such as geometry, kinematics and dynamics, etc. The forming process involves not only transverse bending, but also other additional deformations. In this paper, a group of simulations have been established with ABAQUS software to studying about the spring back and bow defect in the roll forming process. At last, experiments have been accomplished to verify the simulation results. The simulations based on the ABAQUS software calculate the spring back angles and bow displacements. The bow displacement of the roll forming process is considered relate to many factors include inner distance between stands, gaps of the rolls, channel width, the material of the sheet, sheet thickness and so on.To verify the bow displacement in roll forming process, 9 groups of simulations were set up use Taguchi method to figure out the influence on bow displacement of every factor. The longitudinal strain also has been learned in the present study.

Abstract: This research is focused on the helical blades used in the reel mower machine which uses 5 to 10 helical blades. These blades are normally manufactured using the roll forming process which has certain tolerance. This research is to develop an iterative methodology to optimize the manufacture of blades using roll forming. To save cost, time and waste of material the computerized simulation process is being used. The design of the blade and the die for the roll forming and modification are done using software SolidWorks. Simulation is performed using software DEFORM-3D. The simulation result and the actual design are compared using software Geomagic. This study also shows the potential applications of computer aided engineering and its benefits in verifying and reinventing the part manufacturing process.