Flexible Roll Research Articles

Research on forming effect of material with different thickness structure in continuous flexible rolling process

Continuous flexible rolling is a novel advanced manufacturing technology for vehicle body surface, the forming mechanism of this process is based on the uneven thickness reduction of rolled plate along the transversal direction. In the rolling forming process, working hardening is always an important factor for affecting thickness reduction of rolled plate. In this work, the method of decreasing working hardening was studied deeply in continuous flexible rolling process for 3D surface. By finite element analysis, the forming effect of metal plate with different thickness structure was studied in continuous flexible rolling process. The rolled plate consists of three piece of metal plate; in the comparing experiments, the total thickness of rolled plate is 3mm, from compression surface to tension surface, the thickness ratio of each layer metal plate is 1:1:1, 1:2:2, 2:1:2, 2:2:1 in order. The results show that: with the location of the thinnest metal plate moves down, plastic strain in the middle surface of rolled plate is increasing greatly, the thickness reduction is also improving significantly, and the thickness distribution is almost unchanged. Therefore, to optimize rationally the thickness structure is an effective method to decreasing working hardening, the forming precision of 3D surface can get improving in continuous flexible rolling process.

On Recoated Powder Quality with a Forward Rotating Flexible Roller in Laser Powder Bed Fusion of 30wt% 5μm Sicp/Alsi10mg Composites

On Recoated Powder Quality with a Forward Rotating Flexible Roller in Laser Powder Bed Fusion of 30wt% 5μm Sicp/Alsi10mg Composites

A continuous spatial confining process towards high electrical conductivity of elastomer composites with a low percolation threshold

Electrically conducting elastomer composites are indispensable in the development of flexible, wearable and soft electronic products. The continuous fabrication of highly electrically conductive polymeric composites at large scale remains a technical challenge due to the lack of control of the dispersion and orientation of the conductive fillers, interfacial interaction and filler-filler network stability in the polymer matrices. Herein, an innovative design was investigated by combining continuous compression molding and curing through a flexible roller enabled continuous process. This approach forced the alignment of short carbon fibers (SCF) along the rolling direction in a polydimethylsiloxane (PDMS) matrix due to the deformation of the flexible roller and effectively condensed the conductive SCF network in PDMS. The distance between SCFs can be further reduced with the rolling cycles which is ascribed to a spatial confining-forced network assembly. With a rolling cycle of 20, dual electrical conducting percolation thresholds reached at 0.1 wt% and 0.5 wt% SCF, respectively. A maximum electrical conductivity of 49.69 S/m was achieved with a SCF loading of 4 wt%. A fiber contact model was proposed to predict the electrical conductivity of the composites. The PDMS/SCF composites were tested for conductive electrodes and flexible pressure sensors. The present work provides a facile method for continuous fabrication of conductive elastomeric composites, with potential for continuous fabrication of thermosetting composites.

Dynamic Recrystallization Behavior of Low‐Carbon Steel during the Flexible Rolling Process: Modeling and Characterization

Dynamic recrystallization (DRX) is the predominant softening mechanism under high‐temperature large‐plastic deformation and determines the microstructure evolution of steel. Herein, an equivalent substitution method is proposed to investigate the coupling effect of deformation conditions on microstructural evolution during the flexible rolling process. Low‐carbon steel is compressed using a Gleeble 3800‐GTC thermal–mechanical physical simulation system at temperatures ranging from 900 to 1100 °C and strain rates ranging from 0.01 to 10 s−1. The flow stress behaviors under different deformation conditions are discussed. Accordingly, the relationship between strain rate and temperature is established using the Zener–Hollomon equation. Further, a new DRX model is proposed by combining the theoretical implications of previous models. The effectiveness of the experimental model and predicted model is statistically evaluated to accurately determine the DRX volume fraction of the experimental steel. Based on the dynamic material model, a hot processing map of the experimental steel is also developed to evaluate the steel's hot workability. Finally, the microstructure of the experimental steel is analyzed under specific deformation parameters. The results demonstrate that DRX behavior decreases as the upper roller is raised and the lower roller is lowered during the flexible rolling process.

Optimising part quality in the flexible roll forming of an automotive component

Optimising part quality in the flexible roll forming of an automotive component

Characterization of dynamic recrystallization behavior of low carbon steel under flexible rolling process

The uplifting process of the flexible rolling causes different deformations at different positions of the rolled strip, which will affect the microstructure and dynamic recrystallization behavior of the material under the coupling effect of contact heat transfer and plastic deformation. The equivalent substitution method and the Gleeble-3800 thermal simulation experimental machine were used to study the effect of dynamic recrystallization behavior of a low carbon steel in the flexible rolling process at a temperature of 900–1100 °C, a strain rate of 0.01–10 s−1, and strains in the range 0.2–1.2. Firstly, the critical condition of dynamic recrystallization was determined by analyzing the flow stress curve at high temperature, and the Zener-Hollomon equation under the coupling interaction of stress, strain rate, and temperature was established. Secondly, the method of solving the dynamic recovery coefficient r is optimized, and the dynamic recrystallization volume fraction model is established based on the optimized model, and the experimental value is compared with the predicted value. Finally, the microstructure of the experimental steel was analyzed. Through the equivalent substitution method, it can be concluded that as the roll uplifting reduces the reduction of the strip during the flexible rolling process, the number of dynamically recrystallized grains decreases with the decrease of deformation degree.

The flexible rolling process of three-dimensional curved parts using an auxiliary plate based on rigid arc-shaped rollers

The flexible rolling process of three-dimensional curved parts using an auxiliary plate based on rigid arc-shaped rollers

On the prediction of wrinkling in flexible roll forming

Flexible roll forming process is an advanced manufacturing process, for producing complex and lightweight profiles with variable cross-section. One of the major observed defects in this process is the flange wrinkling of the profiles, which has limited its development especially for the automotive industry. In this paper, the deformation mechanics of the flexible roll forming process is revisited, and the methodology for predicting the onset of wrinkling, which had previously been developed based on the wrinkling limit curve in the space of effective strain versus stress triaxiality, is improved. Then, a new criterion based on the wrinkling limit curve is proposed to predict the possibility of wrinkling in finite element analysis. The criterion is applied to analyze the influence of geometric parameters of the variable cross-section profile and material properties of the sheet on the occurrence of wrinkling. The prediction accuracy is evaluated by performing experiments with different profile shapes. Results show that the new proposed criterion can successfully predict the onset of wrinkling in the flexible roll forming process, and its utilization is recommended for predicting wrinkling in the finite element analysis of sheet metal forming processes.

Modeling of Performance Decay Prediction Based on LSTM-SVM Flexible Circuit Board Processing Roll

The roller is the core component of the flexible material roll-to-roll equipment, and its performance will affect the processing quality, so it is necessary to predict the health of the roller. In order to improve the prediction accuracy and effectively extract the time sequence information hidden in the signal, a LSTM-SVM-based processing roll performance degradation prediction model is proposed. By collecting the bearing vibration sensor data, extracting the characteristics of the vibration signal after normalization, using the extracted features as the input of the prediction model, inputting a part of the samples as the training set into the LSTM-SVM prediction model, and inputting the model in batches for network training, and Adjustment parameters. After the model is trained, use the test set for testing. Compared with support vector machines, the SLTM-SVM model is more effective in predicting the performance degradation of roll-to-roll equipment.

Effect of asymmetry forming technology on longitude curvature radius of 3D curved part in continuous flexible rolling process

Continuous flexible rolling is a novel plastic forming process for 3D curved parts. In this work, asymmetry forming technology was firstly applied in continuous flexible rolling process, which can effectively compensate the lack of longitude bending deformation caused by work hardening. In the process of asymmetry forming technology, by changing the relative longitude elongation between the tensile surface and compressive surface of the sheet metal, the adjusting of longitudinal bending deformation is achieved. In this paper, the finite element model with different friction ratio was designed; the effect of asymmetry forming technology on longitude curvature radius of 3D curved parts was studied. As results demonstrate that: When the friction ratio between the upper (compressive) and lower (tensile) surface are 0.2:0.2, 0.2:0.15, 0.2:0.10, 0.2:0.05 and 0.2:0.2, 0.15:0.2, 0.10:0.2, 0.05:0.2 in turn, the corresponding longitude curvature radiuses of convex curved parts are 226 mm, 236 mm, 254 mm, 272 mm and 226 mm, 219 mm, 207 mm, 199 mm in turn. When the friction ratio between the upper (tensile) and lower (compressive) surface are 0.2:0.2, 0.2:0.16, 0.2:0.12, 0.2:0.08 and 0.2:0.2, 0.16:0.2, 0.12:0.2, 0.08:0.2 in turn, the corresponding longitude curvature radius of saddle curved parts are 330 mm, 321 mm, 315 mm, 306 mm and 330 mm, 339 mm, 345 mm, 350 mm in turn. The longitude bending deformation of sheet metal can be effectively adjusted in the asymmetry forming technology, so the feasibility of this technology is verified.

Application of Support Vector Regression and Genetic Algorithm to Reduce Web Warping in Flexible Roll-Forming Process

Abstract In a flexible roll-forming process, a metal blank is incrementally deformed into the desired shape with a variable cross-sectional profile by passing the blank through a series of forming rolls. Because of the combined effects of process and material parameters on the quality of the roll-formed product, the approaches used to optimize the roll-forming process have been largely based on experience and trial-and-error methods. Web warping is one of the major shape defects encountered in flexible roll forming. In this study, an optimization method was developed using support vector regression (SVR) and a genetic algorithm (GA) to reduce web warping in flexible roll forming. An SVR model was developed to predict the web-warping height, and a response surface method was used to investigate the effect of the process parameters. In the development of these predictive models, three process parameters—the forming-roll speed condition, leveling-roll height, and bend angle—were considered as the model inputs, and the web-warping height was used as the response variable. The GA used the web-warping height and the cost of the roll-forming system as the fitness function to optimize the process parameters of the flexible roll-forming process. When the flexible roll-forming process was carried out using the optimized process parameters, the obtained experimental results indicated a reduction in web warping. Hence, the feasibility of the proposed optimization method was confirmed.

Effect of the arc profile roll gap on forming results in flexible rolling process

Flexible rolling is a new-style process, it is suitable to produce the small batch and various size forming parts. In this paper, a new design scheme of roll gap was applied to form spherical surface. Two arc with different curvature radius are used as the upper and lower profile of the roll gap. Theoretically, the smooth and continuous arc can’t cause instability and wrinkling in the local area of sheet metal. Based on the process of flexible rolling, the finite element model was established, and the boundary conditions were determined. The forming process of spherical surface formed by arc profile roll gap was simulated. The results show that: By simulating forming process, the forming part is smooth without forming defects, the forming quality is better, it verifies the feasibility of the application.

Research on the influence of end effect on forming result of saddle curved part in flexible rolling process

Flexible rolling is suitable to manufacture small batch of 3D curvature parts with various shapes. In this paper, the influence of end effect on saddle curved part was studied firstly. The finite element model was designed based on the flexible rolling forming apparatus. The areas characteristics of forming saddle curved part were analysed, and the influence of end effect on the saddle curved part with different forming size was studied. The results demonstrate that: the forming saddle curved part consists of three forming areas by characteristics, and the forming mechanism of each forming area is analyzed deeply; under the end effect action, with the sheet length increases, the plastic strain and minimum forming thickness of forming curved part are stable; when the sheet length is 200mm, 300mm, 400mm and 500mm, the percent of the stable forming area of forming curved part is 52%, 72%, 79% and 83% respectively, and the percent of stable forming area increases by 20%, 27%, 31% respectively, therefore the utilization rate is obviously improved. With the increasing sheet width, the plastic strain is increasing and the minimum forming thickness is decreased; when the sheet width is 85mm, 90mm, 95mm and 100mm, the percent of stable forming area of forming curved part is 67%, 61%, 59%, 58% respectively, and the percent of stable forming area decreases by 6%, 8%, 9% respectively, therefore the utilization rate is decreasing.

Springback and end flare compensation in flexible roll forming

Flexible roll forming enables the forming of complex automotive components from Advanced High Strength Steels (AHSS) and Ultra High Strength Steel (UHSS) but common shape defects such as end flare and springback occur and need to be compensated. In flexible roll forming a pre-cut blank is fed through a set of rolls which are computer numerically controlled (CNC) to follow the 3D contour of the part. The company, dataM Sheet Metal Solutions, have established a new 3D flexible roll forming facility at Deakin University which allows the manufacture of flexible roll formed prototypes.In this study, Deakin’s flexible roll forming facility is employed to implement an approach to overcome springback and end flare defects in a flexible roll formed automotive component of variable width. To do this, the flexible roll forming process is simulated using the commercial software package Copra FEA. Non-uniform springback due to end flare is observed and a variable overbending approach developed and implemented to overcome this defect. Experimental validation is performed on Deakin’s flexible roll forming facility and the results suggest that the flexible overbending approach can be used to control final shape in flexibly roll formed components.

Application and Progress of Microstructure and Mechanical properties Control Methods for Ultra-High Strength Steel in Rolling Process

This paper introduces traditional ultra-high steels and the dilemma of its processing, the application of the rolling method in the production of ultra-high strength steel, Nano-fine grain preparation techniques for improvement of strength and toughness, Phase composition regulation to improve mechanical properties. Summed up microstructure and mechanical properties control methods for ultra-high strength steel in the rolling process, Using the methods innovatively solves the flexible rolling process produces 1600 MPa grade ultra-high strength and toughness nano-scale B/M complex phase under the existing equipment conditions of ordinary steel enterprises.

The flower pattern and rolls design for ERW pipes with the different specification in the flexible roll forming process

To produce electrical resistance welding (ERW) pipes with the different specification efficiently and economically, flexible roll forming technology is urgently required. Based on the elastic plasticity deformation theory, combined with the basic parameters of typical roll forming units, the 3D finite element analysis (FEA)models of ERW pipes with seven kinds of sizes were built and the numerical simulations were conducted with the professional roll forming software COPRA. The mechanics law between strip and rolls in conventional roll forming was revealed and the results were obtained that the edge arc segment of rolls plays a major role and the straight segment restricts the deformation of strip in the W-shaped forming process. Considered the mechanics law and forming mechanism, the modular and compact design of flower pattern and rolls in first to fifth stands were conducted; a set of involute-tangent-arc roll profile for flexible roll forming of ERW pipes with seven kinds of sizes in first to fifth stands was proposed and verified with the numerical simulations. Results showed that the final product with the flexible design of flower pattern and rolls satisfied the accuracy requirement and the transverse strain distribution was optimized during the roll forming. The flexible roll forming technology reduces the time and costs for the preparation and replacement of rolls in first to fifth stands when ERW pipes with the different specification are produced, and the total weight of rolls is reduced by about 35%, realizing the lightweight production, which provides a novel method for the flexible roll forming of ERW pipes.

Understanding the role of water-based nanolubricants in micro flexible rolling of aluminium

To comprehend the role of water-based nanolubricant in micro flexible rolling, corresponding characterisation with respect to different concentrations of nanolubricants, surface roughness variation subjected to each micro flexible rolling phase and dispersion of nanoparticles (NPs) were studied systematically. The results reveal that increasing NPs get trapped into the surfaces from the thicker zone to the thinner zone. Downward transition zone with favourable deformation features leads to the smoother surface roughness. Nanolubricants can effectively decrease rolling traces due to the beneficial nanolubrication mechanisms. Notably, the maximum reduction for rolling force is around 18% for the case under 2.0 wt% nanolubricant rolling condition. The current study provides great potential insights in how nanolubrication takes effect in microforming areas.

Non-sorting multi-objective optimization of flexible roll forming using artificial neural networks

The main defects due to flexible roll forming (FRF) processes include longitudinal bow and wrinkling. In this study, experimental and numerical analyses were performed using three different blank shapes to characterize the effects of the process parameters on defects in parts fabricated by FRF with and without leveling roll. Owing to the complexity of the FRF process, two algorithms were combined for its optimization. Artificial neural network-based Non-dominated Sorting Genetic Algorithm II (NSGA-II) was used to optimize the effective parameters of the FRF process, such as the sheet thickness, yield strength, and blank shape, with respect to the target bend angle to minimize the longitudinal bow and wrinkling of the product. The back-propagation neural network (BPNN) was used to identify two objective functions, while non-sorting multi-objective algorithm simulation was used to optimize the input parameters to minimize the objective functions. The results showed that the sheet thickness had the greatest effect on the minimization of the two objective functions, followed by the yield strength and blank shape, respectively.

Effect of Roll Gap Setup on Shape Defects during a Flexible Roll Forming Process

Effect of Roll Gap Setup on Shape Defects during a Flexible Roll Forming Process

Annealing of HC340LA tailor rolled blanks—Control of mechanical properties and formability

Abstract Tailor rolled blanks (TRB) have been extensively used in the automotive industry because of lightweight. Through the flexible rolling process and appropriate annealing treatment, the target geometry, required mechanical properties, and good formability of TRB can be achieved. In this study, two types of annealing processes were attempted, i.e. batch annealing and continuous annealing. The effects of annealing parameters on the microstructure, mechanical properties and formability of HC340LA TRB were investigated. First, a series of batch annealing and continuous annealing were conducted on cold rolled TRB. Next, the microstructure distribution of TRB was evaluated. The mechanical properties and formability of annealed specimens were tested through the uniaxial tensile test and Erichsen cupping test, respectively. The results showed that the mechanical properties and formability were controlled by reduction, annealing type and annealing parameters. During the batch annealing, mechanical properties along the rolling direction were influenced by the degree of recrystallization and the average grain size, the formability increased with the increase of annealing temperature. TRB annealed at 700 °C for 60 min showed relatively homogeneous mechanical properties and good formability in the reduction range of 36–54 %. During continuous annealing, the mechanical properties and formability were determined by the degree of austenitization and the average grain size. TRB annealed at 930–950 °C for 3 min showed homogeneous mechanical properties and good formability for the entire range of reduction.