Numerical Analysis of Edge Cracking in High-Silicon Steel during Cold Rolling with 3D Fracture Locus

In this study, a 3D fracture locus of high-silicon steel strip was constructed through a series of fracture tests with specimens of various shapes and corresponding finite element (FE) simulations of the fracture tests. A series of FE analyses coupled with the developed fracture locus was conducted, and the effect of the secondary roll-bending ratio (defined as L2/R2, where L2 and R2, respectively, denote the secondary work roll barrel length and the radius of the convex curvature of the work roll surface profile emulating positive roll bending) and the initial notch length on edge cracking in the strip during cold rolling was investigated. The results reveal that the 2D fracture locus that does not include the Lode angle parameter (varying between −0.81 and 0.72 during cold rolling) overestimates the edge cracking in the range of 13.1–22.2%. The effect of the initial notch length on the length of crack grown in the transverse direction of the strip during cold rolling is greatest when the ratio L2/R2 is 0.12.

Evolution of Stress and Strain in 2219 Aluminum Alloy Ring During Roll-Bending Process

The large quenched residual stress of large-scale aluminum alloy ring component induces severe deformation in the subsequent maching process. The conventional methods for reduction of residual stress (such as stepwise cold pressing and bulging) have little effect in the residual stress reduction for large-scale ring component and will induce inhomogeneous stress distribution. In this paper, roll bending process is adopted to reduce the quenched residual stress of 2219 aluminum alloy super-large ring. The numerical model of roll bending process was established, and the evolution and distribution of stress and strain after roll bending were studied. The influence of roll winding number on the uniformity of stress and strain was analyzed. The results show that the arch-shaped quenched residual stress of the ring changes to N-shaped distribution from inside to outside after roll bending process. The value of the residual stress reduces from ±180MPa in quenched state to the value within ±50MPa in roll bended state. With the increase of roll winding number, the stress uniformity is improved, but the stress reduction amplitude is basically the same. By analyzing the elastic-plastic strain distribution characteristics and strain springback law of the ring after roll bending, the formation mechanism of N-shaped residual stress distribution after roll bending is revealed.

Research on a Control Strategy of the Symmetrical Four-Roller Bending Process Based on Experiment and Numerical Simulation

The intelligent production of sheet metal is a comprehensive technology involving control science, computer science, and sheet metal production. Intelligent rolling is an important development in the production process of sheet metal. In this paper, a new symmetrical four-roller bending (SFRB) process is introduced, which consists of feeding, pre-bending, reverse roll bending, second bending, and forward roll bending and unloading. A control strategy is proposed for the process, including on-line monitoring of curvature, on-line identification of the springback law, on-line prediction of final reduction, and control strategy. A convenient and reliable on-line curvature monitoring method is proposed. The quantitative relationship between the reduction and the curvature, in the form of a quadratic function, was established by physical experiments and numerical simulation, and the online identification of the springback law was realized. An on-line prediction method of the final reduction is proposed, and the determination principle of the reduction of three pre-bending processes is given. Finally, the control strategy of the SFRB process was verified by physical experiments. The relative error of the curvature radius of the final formed parts can be controlled within 0.8%. This research provides new insights into intelligent rolling.

Expansion of oval tubes: prediction and experiment

The manufacturing of oval tubes for automotive components from sheets consists of several steps, from the flat sheet to a tube with expanded ends. It involves roll-bending of tubes, welding and several expansion processes with segmented tools. Forming steps in this process are subject to springback after the release of tools. Finite-element-simulations offer an efficient method to predict the springback behavior. For the industrial application it is important to identify the processes which contribute significantly to springback. At first glance one might expect that the consideration of the whole process chain is required to predict the final shape of such tubes. It turns out, that springback is related to the later stages of the process. The difference in springback behavior of circular and oval tubes is investigated. A simulation model is validated on the basis of experiments for circular tubes and applied to predict the final shape of oval tubes. This offers the perspective to adjust the tooling design at an earlier design stage to respect all the influences in the process on the final geometry and therefore meet tighter tolerances.

Perancangan Mekanisme Pelurusan Kawat SAE 304 (UNS S30400) Galvanized Menggunakan Prinsip Pengerolan

Wire is a complement material on the manufacturing product. Therefore, the wire processes usually bestowed to the middle-low industry. Cutting and straightening wire processes are the most basic process for wire materials. In the middle-small industry, demand of wire materials is 150 kg per day. Seeing this potential, the design of a wire straightening mechanism for middle-low industries is necessary to maximize productivity. The main purpose of wire straightening mechanism design is calculating roll diameters and placement to obtain appropriate rolling force. In designing this wire straightening mechanism, the raw materials are used 3 mm SAE 304 (UNS S30400) Galvanized. The rolling method used in this mechanism is Three-Roll Bending. The empirical method is used on this analysis. Based on the analytical results, roll used on this mechanism are 5 pieces or equal with 3 cycle of rolling process with 40 mm of diameters. The vertical gap between center of rolls is 41.5 mm with 54 mm horizontal gap. Rolling force produced by the analytical roll dimension is 1608.69 N/cycle and that’s enough to give plastic deformation on the 3 mm SAE 304 (UNS S30400) Galvanized wire.

Research on Comparison of Simulation and Experiment in Warpage Defects in Roll Forming Process of the Cap-Shaped Part Using a Five-Boundary Condition Forming Angle Distribution Function

Warpage is one of the main defects in multi-pass roll forming. It manifests as the horizontal deviation in the sheet flange part after forming, impacting the final quality of the sheet. In this manuscript, we focus on the cap-shaped part of a small section profile. Considering the lack of previous scientific guidance on the distribution of forming angles—angles that lead to warpage defects and other defects reducing the quality of these products—a five-boundary condition distribution function of forming angle is proposed. We propose a mechanism for warpage defects in roll bending of a cap-shaped part based on this five-boundary condition forming angle distribution function. Furthermore, we examine the effects of forming angle, sheet thickness, and material yield strength on the warpage defects by examining the designed fluctuation of the edge wave, ∆z, and the maximum deviation of the profile curves of the flange edge, z', to test this theory, roll bending experiments are compared to simulation.