Due to their characteristics of a high power-to-weight ratio, stringent lightweight requirements, and harsh working environments, straight face gears are prone to issues such as tooth fracture and inadequate fatigue strength. Meanwhile, because of the lack of fatigue information and weak fatigue life prediction method, the fatigue life of face gears cannot be effectively evaluated. In this study, the key technologies involved in the hot rolling forming process, fatigue experiments, and numerical modeling of straight face gears are studied. A technical foundation for straight face gears formed by hot rolling processing is established, and a fatigue experiment of the hot rolling forming of straight face gears is carried out. Due to the lack of information on fatigue experiments, a numerical prediction model is constructed. Sample expansion is carried out using a BP neural network–Bootstrap model to calculate the reliable lifespan of hot-rolled straight face gears, and fatigue life prediction for hot-rolled straight face gears is completed via the improved GM(1,1,λ) model based on the artificial bee colony algorithm, and thus the accurate evaluation of the fatigue life of rolling forming face gears is realized. The feasibility and superiority of the improved fatigue life prediction model are demonstrated by comparing it with the traditional prediction model and experimental results. The theoretical basis and technical support for the research of the fatigue resistance and installation application of face gears are provided.

Edge cracking is prone to occur during the rolling of Mg/Al composite foils. Herein, a hybrid hot-cold rolling process was adopted to fabricate 30 μm thick Mg/Al composite foils with low edge cracking. AZ31B magnesium alloy and 5052 aluminum alloy sheets, both with an initial thickness of 0.5 mm, were chosen as research materials. Numerical simulations of composite pass were conducted at 300-450 °C with reduction ratios of 25-40%, and the optimal parameters were identified as 400 °C and a 35% reduction ratio. Based on this, multi-pass rolling experiments were performed: composite pass was heated at 400 °C for 10 min with 35% reduction ratio, hot rolling passes at 300 °C for 1-3 min, and subsequent cold rolling with 15% reduction ratio. After 21 rolling passes, 30 μm thick Mg/Al composite foils with low edge cracking were successfully prepared. Interface and metallographic characterizations demonstrated that the diffusion layer thickness varied slightly during hot rolling and increased moderately during cold rolling. For the magnesium alloy, hot rolling improved microstructural uniformity and reduced shear bands, while cold rolling caused decreased uniformity and the gradual emergence of shear bands. The research results provide a reference for the preparation of high-quality Mg/Al composite foils.

Investigation on corner thickening mechanism of Q460NH square tube using "Ω" new pass design in the hot roll forming

The conventional flat rolling (FR) process suffers from low bonding strength and significant edge cracks when preparing Mg/Al laminates. This paper proposes a Lattice Severe Deformation Pre-Rolling (LSDPR) corrugated interface scheme and compares it with the FR process. The forming characteristics of Mg/Al laminates prepared using the LSDPR process were investigated through experimental and simulation methods. The results show that the bonding interface of Mg/Al laminates prepared by LSDPR exhibits an obvious three-dimensional network of corrugations. Compared to the FR process, the bonding area at the interface increases, and multiple cross-shear bands are formed. This accelerates the cracking of metal oxide film, the forming of the hardened layer at the interface and the diffusion of elements. Furthermore, the waveform structure provides a mechanical interlocking effect, significantly enhancing the bonding strength. The trough positions of Mg/Al laminates prepared by LSDPR exhibit the highest shear strength, with values of 58.81 MPa and 55.93 MPa along the transverse direction (TD) and rolling direction (RD), respectively. These values are 52.5% and 78.4% higher than the shear strengths of 38.56 MPa and 31.34 MPa in the FR process. Additionally, the LSDPR process helps suppress edge cracks in the magnetism alloy plate. The corrugated structure along the TD inhibits the inward propagation of edge cracks, and the structure along the RD distributes the damage, making the edge damage at the peak lower than that at the trough, which effectively prevents the initiation and expansion of edge cracks. The proposed LSDPR process provides a valuable reference for the roll forming of high-quality metal laminates.

This study investigates the technological and chemical causes of early zinc-coating degradation on cold-formed steel sections produced from DX51D+Z140 galvanized coils. Commercially manufactured products exhibiting early corrosion symptoms were used in this study. The entire processing route, which included strip preparation, cold rolling, hot-dip galvanizing, passivation, multi-roll forming, storage, and transportation to customers, was analyzed with respect to the residual surface chemistry and process-related deviations that affect the coating integrity. Thirty-three specimens were examined using electromagnetic measurements of coating thickness. Statistical analysis based on the Cochran’s and Fisher’s criteria confirmed that the increased variability in zinc coating thickness is associated with a higher susceptibility to localized corrosion. Surface and chemical analysis revealed chloride contamination on the outer surface, absence of detectable Cr(VI) residues indicative of insufficient passivation, iron oxide inclusions beneath the zinc coating originating from the strip preparation, traces of organic emulsion residues impairing wetting and adhesion, and micro-defects related to deformation during roll forming. Early zinc coating degradation was shown to result from the cumulative action of multiple technological (surface damage during rolling, variation in the coating thickness) and environmental (moisture during storage and transportation) parameters. On the basis of the obtained results, a methodology was proposed to prevent steel product corrosion in industrial conditions.

Abstract Storage rack legs are made of various materials and using various technologies. The selection of the appropriate material and technology depends on many factors such as: production volume, storage rack load capacity, purpose, etc. In the case of using steel legs, their production technologies may also be different. In the case of storage racks with a high load-bearing capacity, mainly cold-bent profiles (usually angle bars) are used. For medium and lower load capacities, additional shaping is attempted to protect the dangerous edges of the rack legs from injury during assembly and use, as well as to achieve adequate stiffness with the lowest possible material consumption. This paper attempts to develop a roll forming process for rack legs with a safe edge. For each profiling section, roll shapes were proposed and the profiling process was simulated using the Simufact Forming program. As part of the simulation, the forces acting on individual sections of the profiling roller sets and the shape of the storage rack legs were obtained similar to the previously assumed shape.

Abstract Ensuring the stability and safety of steel storage racks is essential to withstand applied loads over time. Rack columns are typically produced through a cold roll‐forming, enabling high productivity and open‐section profiles, known as uprights. However, roll‐forming imperfections can adversely affect buckling capacity. Stub column compression tests, as defined by the EN 15512 standard, experimentally determine the buckling capacity, while numerical methods further analyze it. A common way to introduce geometric imperfections in FEM models is by superposing scaled eigenmodes obtained from an elastic buckling analysis. Although standards specify imperfection types (local, distortional, global) and magnitudes, combining them remains unclear, often requiring multiple scenarios that may overly penalize capacity, as some imperfections rarely occur simultaneously. This work determines imperfection values from predefined roll‐forming imperfections and identifies which combination most significantly affects open‐section column buckling capacity. The initial roll‐forming imperfections were measured and each amplitude established. A FEM model incorporating these imperfections was developed and validated against experimental data. Finally, the effects of these errors and their most critical combination on buckling capacity were determined, contributing to improved design procedures and a more reliable assessment of structural performance.

Coiled tubing (CT) is an efficient method used in petroleum well drilling, involving winding a High Strength Low Alloy (HSLA), flexible metal tube onto a reel, creating thousands of meters in length. The tube is unwound, straightened, and inserted into the well, repeating until the tubing requires removal due to fatigue. Precise manufacturing of these tubes is crucial for their mechanical resistance, performance, and lifespan. This study introduces a hybrid analytical-numerical geometric approach, referred to as the Geometry-Based Method, to predict spring-back effects during the roll-forming process of thin-walled tubes. Specifically, it simulates the roll-forming of a 1.5 inches (38.2 mm) QT-70 tube using a reverse bending flower pattern. Following this, a 12-m tube was manufactured using the same technique. Results show strong agreement between theoretical predictions and experimental findings, with the simulation showing no errors in average thickness. The experimental error was just 0.32%, but the simulated tube had an ovality of 2.68%, compared to 1.80% for the manufactured tube. In conclusion, the Geometry-Based Method uses three-dimensional geometry to analyze the properties of forming materials and rollers, helping manufacturers reduce costs while maintaining accuracy.

A New Forming Method of Titanium Bipolar Plate for PEMFC: Multi-step Rolling Forming

Abstract Roll forming is a sheet metal forming process used in a wide range of manufacturing industries that has high material utilisation and high production rates. The raw material is incrementally bent into the desired shape by consecutive forming stands. Due to the spatial bending, different longitudinal strains develop along the profile cross-section, leading to defects such as horizontal and vertical bowing or twisting. As a result, it is often necessary to rework the parts using straighteners. Their adjustment is typically based on trial-and-error procedures that are manual work intensive and dependent on individual experience. To obtain a higher level of automation, this paper presents a novel data-driven approach to controlling a straightener. Reinforcement Learning is used to control the complex system by learning through interaction. To generate the data needed for learning, a simulation pipeline is implemented, focusing on a symmetric hat profile. The core of the approach is a model-free Soft Actor-Critic algorithm for determining the optimal position of the straightening device. The algorithm was able to predict an optimal position for a specific maladjustment in all test cases and for a varying misalignment in eight out of nine cases.

Abstract With the rapid development of the electric vehicle industry, the safety and lightweight of battery pack frames have become key design factors. This paper studies the application of advanced high-strength steel (AHSS) in battery pack frames, especially the roll forming process. Modal analysis was used to evaluate the vibration characteristics of different AHSS materials, revealing that materials with the tensile strength from 1180MPa to 1470MPa can achieve an optimal balance between lightweight and safety performance. The study also optimised the roll forming process and die design and solved the cracking, spring-back and warping problems of AHSS in cold stamping. A 32-station roll forming line was employed to produce battery pack frames with high precision and efficiency through laser welding. The results demonstrate the suitability of roll forming technology for AHSS materials and its effectiveness in the manufacture of electric vehicle battery pack frames.

Abstract This study adopts the method combining experiments and numerical simulations to investigate the springback of roll forming. The forming force and hardness of each pass from 0° to 50° were measured, and the springback rate of each pass was calculated. The research results show that the change in hardness is similar to the change in springback rates. The work hardening phenomenon on the outside of the corner is larger than that on the inside of the corner. The springback phenomenon of the sheet metal under repeated overbending and rebending is analyzed through a numerical model. The springback decreases when the number of gradual approximation passes increases.

To meet forming requirements for sheets of varying thicknesses, the roll gap size must be adjusted regularly during the roll forming process. Traditional manual adjusting methods have low efficiency and high mistake rates. To address this issue, we present a unique electromagnetic sheet-thickness-adaptive roll forming auxiliary device that is essentially an adjustable-stiffness spring device with an electromagnetic spring and a disc spring functioning in parallel. Finite element analysis was utilized to improve the structural dimensions of the device, and a performance test was carried out to guarantee that it operated smoothly. The stiffness of the devices may be quickly adjusted by changing the current. The experimental peak value of the electromagnetic force of an electromagnetic spring under a particular current differed by no more than 5.7% from the simulation value. The application results of the proposed device with a roll forming machine show that when forming a given sheet thickness, the forming force of the roll forming machine in the adaptive forming mode is stable to within 10% of the forming force in the traditional forming mode, achieving the goal of adaptive roll forming. As a result, an adjustable stiffness spring device can solve the roll gap and forming force adaption problems encountered during the roll forming process.

Porous aluminum is a multi-functional porous material. This is a lightweight and low-density material with excellent shock absorption, thermal insulation and sound absorption properties. In this study, the precursors were fabricated by a friction stir welding process, which involved the butt-joining of A1050 aluminum and A6061 aluminum alloy precursors. We foamed the joined precursor by heating with halogen lamps. Immediately after foaming, roll forming was conducted. The X-ray CT images of the samples obtained in the experiment show that the porosity of the samples was maintained after they were roll formed. In addition, the fracture surfaces of the samples obtained via four-point bending test had a porous structure, indicating that A1050 aluminum and A6061 aluminum alloy were metallurgically joined. Furthermore, we prepared samples with the addition of iron powder to the A6061 side. The X-ray CT image of this sample showed that a mixture of the two metals can be formed, and it was confirmed that a two-layered porous aluminum can be obtained.

Increased demands on lightweight and high-performance battery casings of electric vehicles (EVs) and energy storage systems require cutting-edge forming technology to overcome challenges of conventional deep drawing and stamping, where usually thickness inhomogeneity, residual stress, and defects would be caused. The research deals with the designing and optimisation of an ultra-thin square aluminium shell power battery forming die utilising roll forming technology for improving size accuracy and mechanical reliability. A finite element model for simulation to optimise roll forming parameters, such as rolling force and pass geometry, was established and verified experimentally for thickness distribution assessment, defect minimisation, and spring back minimisation. The comparative study against deep drawing and stamping techniques reveals that roll forming results in 50% thickness variation reduction, 63% dimensional accuracy improvement, and 75% defect rate minimization. Furthermore, spring back effects were decreased by 42–60%, and shape retention and structural stability were improved. The results confirm that roll forming enhances production accuracy, reduces human errors, and improves overall efficiency, making it a good candidate for scalable next-generation production of batteries. From the data, it can be deduced that roll forming is a better alternative when compared to traditional forming as it helps in achieving better sustainability, less material waste, and increased reliability for future energy storage technologies.

Set-up and validation of numerical modeling techniques to simulate the cold roll forming of martensitic and high strength steel

The paper provides an analyzes modern technologies of roll forming for 3D-bent profiles and their applications in the automotive industry, construction, manufacturing, and agriculture. Approaches to optimizing the number of technological transitions are considered, contributing to reduced production time and increased productivity. Special attention is given to controlling the stress-strain state of the metal, which is crucial for ensuring high product quality. The impact of sensor technologies on real-time process monitoring is assessed, allowing for defect reduction and lower production costs. The use of advanced solutions in roll forming opens new opportunities for production optimization.

Purpose. To develop an approach for simulating the roll forming process of U-shaped bent profiles using the QForm software package. Methodology. The study is based on the finite element method implemented in QForm. The process was simulated in a 3D environment, accounting for elastic–plastic deformation, using a single operation of the «Sheet Bulk Forming» type. A sequential forming scheme was implemented using 12 roll stands, which incorporated the elastic–plastic properties of the material. Appropriate boundary conditions were defined to replicate real technological parameters of the roll forming process. Results. The simulation yielded stress and strain distributions in the blank at various stages of its passage through the roll stands. It was found that maximum plastic strains occur in the bending zones, while the edge regions are predominantly subjected to tensile stresses. The simulation results are consistent with the physical nature of the bending process and confirm the validity of the proposed approach. Scientific Novelty. An adaptation of the QForm software package is proposed for simulating the roll forming of bent profiles, which is not covered by its standard modules. Simulation algorithm and boundary condition setup were developed, enabling the analysis of the stress–strain state of the blank during profile formation. Practical Significance. The results of the study can be used to optimize technological parameters of the roll forming process, reduce the likelihood of defect formation, and expand the functional capabilities of QForm in the field of sheet metal forming simulation. The proposed approach is valuable for technologists, engineers, designers, and researchers working in the field of metal forming.

This paper evaluates the fatigue life of a roll-formed center sill part in a coil-carrying railway wagon underframe assembly. The loading cycles experienced by this rail wagon architecture are taken from a recorded railroad data available in the Association of American Railroads (AAR) Manual of Standards and Recommended Practices. To estimate the fatigue life of the roll-formed center sill under the given loading history, a two-step finite element (FE) analysis is carried out, considering the residual stresses and thinning introduced in the center sill due to roll forming. Firstly, a COPRA ® FEA RF model is used for roll forming analysis to predict the residual stresses in the center sill, followed by modeling of the actual loading history on the wagon underframe and prediction of fatigue life using commercial FE codes ABAQUS and fe-safe. To validate the results from fe-safe, experimental results of the fatigue tests of pre-strained lab-scale tensile specimens are compared with the predicted values obtained from fe-safe. Our prediction of the roll-formed center sill life shows that the residual stresses introduced due to roll forming are locally detrimental, as the fatigue life is reduced compared to the conventional center sill. This proposed method of evaluating the fatigue life of a part using railroad spectrum load data and roll forming residual stresses developed in the process of center sill fabrication, can be effectively used during the design phase of a rail wagon at both the part and assembly levels.

The torsional behavior during the deformation process of the axial closed die rolling the axial closed rolling (ACDR) forming is studied in this paper using a numerical simulation technique on TC11 titanium alloy. The axial and radial pinch angles, as well as the degree of specimen torsion, increased with the amount of deformation. The orientation distribution function (ODF) maps of the α-phase and β-phase were obtained by Electron Back Scatter Diffraction (EBSD) treatment of the TC11 titanium alloy. It can be noticed that there were different types of texture with different strengths in the ACDR samples, and in the xz and yz planes, textures in the direction of the column were predominantly of {0001} <21¯1¯0> and {011¯0} <21¯1¯0>; the weaker the texture was, the closer to the edge of the sample. In the xy plane, the texture structure was mainly distributed along the cone direction, and the textures were {1¯21¯0} <101¯0> and {011¯0} <21¯1¯0>. However, the closer to the edge position of the specimen, the higher the intensity of the texture, and the texture was {12¯12¯} <12¯16>. The β-phase is mainly distributed as {001} <100>, {110} <11¯0>, and {110} <001> textures within the specimen, and the texture strength is about 8.5 times. However, owing to the small proportion of the β-phase content in the specimen, the distribution pattern of its texture has a weak impact on the texture distribution of the overall specimen. A high degree of isotropy in the radial and tangential tensile properties, with a strength isotropy of over 99 percent and a plasticity isotropy of over 95 percent, resulted from the distribution of texture types with varying strengths and orientations within the ACDR specimens, which weakened the TC11 discs' overall orientation.