Roll Gap Research Articles

Optimization of Grinding Process of Sunflower Meal for Obtaining Protein-Enriched Fractions

In this study, dry fractionation process was proposed in order to obtain protein-enriched sunflower meal fractions. The process includes two-stage grinding using a hammer mill and a roll mill, and fractionation of sunflower meal by sieving. Central composite design (CCD) with four variables on three levels within response surface methodology was applied in order to estimate the influence of grinding parameters (sieve openings diameter of the hammer mill: 2, 4, and 6 mm, roll gap: 0.15, 0.2, and 0.25 mm, feed rate: 0.1, 0.175, and 0.25 kg/cm min, and roll speed: 400, 500, and 600 rpm) on responses (protein content, fraction yield and grinding energy consumption). Sieve openings diameter expressed the highest impact on fraction yield while roll gap expressed the most dominant influence on protein content in the fraction and grinding energy consumption. The highest protein content obtained was 48.06%(dm) with fraction yield of 77.22%. A multi-response optimization procedure was performed and optimal values were: sieve openings diameter of 2 mm, roll gap of 0.25 mm, feed rate of 0.2 kg/cm min, and roll speed of 400 rpm, while predicted values for a desired range of responses were: protein content 45.5%(dm), fraction yield 77.89%, and grinding energy consumption 8.31 Wh/kg.

Experience in obtaining laminated aluminum composites by asymmetric accumulative roll bonding

The issue of asymmetric processing of long products in the range of speed ratios of work rolls from 2 to 5 has not been widely studied and is of interest from the point of view of increasing both the strength and ductility of metal products. An area of severe plastic deformation was found, showing the relationship between shear strain and shear angle, at which large compressive strains and ultra-high shear strains occur. An analysis was made of the values of equivalent deformations of laminated aluminum composites obtained both after the first and second processing cycles, modeled in the DEFORM and QForm software systems. The paper defines a rational range of the speed ratios of work rolls, which makes it possible to obtain not only the rectilinear movement of the metal at the exit from the deformation zone, but also the maximum elongation, the ratio of tensile strength to the yield strength for laminated aluminum composites. A regularity has been deduced showing that with an increase in the speed ratio of work rolls, the rolling forces decrease, the value of the relative reduction at a constant roll gap increases. At the maximum speed ratio of the rolls (5), melting of the samples occurs.

Influence of roll diameter configuration of 20 high mill on roll shifting control characteristics of wide titanium strip cold rolling

In the production of wide titanium strips cold rolled by 20 high mill, when the diameter of the 1st intermediate roll is reduced, the work roll with a large roll diameter will be used to match it, which is called non-standard roll diameter configuration in this study. In order to master the control characteristics of the 1st intermediate roll shifting under non-standard roll diameter configuration, the coupled static model of roll system and strip is established by FEM, and the model is verified by using the corresponding relationship between the change of load roll gap and the change of titanium strip residual stress after cold rolling. The simulation results show that under the same rolling force, the contact stress peaks of non-standard roll diameter configuration in flat area and cone area of the 1st intermediate roll are about 1.44 times and 1.51 times of standard roll diameter configuration respectively. Compared with the standard roll diameter configuration, when the roll shifting amount increases, the longitudinal plastic strain of non-standard roll diameter increases most significantly in the range of 0-300mm from the titanium strip edge. Under the non-standard roll diameter configuration, increasing the roll shifting amount is more prone to occur the high-order buckle problem.

Center Line Globular Structure of Strip Cast Using High Speed Twin Roll Caster

Formation of a centerline globular structure in an aluminum alloy strip cast using a vertical type high-speed twin-roll caster was investigated. The theory that the crystals form at tip of the nozzle and are conveyed to the roll gap was investigated by roll casting using a cooling slope and clad-strip-casting in this study. In high-speed roll casting, the center of the strip thickness is semisolid, and the temperature gradient in the thickness direction is small. The latent heat of the semisolid metal heats the dendrite structure, which is divided by melting. The dendrite structure was divided as in thixocasting, which is the mechanism of formation of a globular crystal form. The zone of the semisolid metal becomes narrow as the roll load increases or the pouring temperature of the molten metal decreases. As result, the zone containing globular crystal structures becomes thinner.

Design and Fabrication of a One Stand Hot Tandem Rolling Mill

Over the years, metalworking processes have emerged as a promising paradigm to modify materials' intrinsic workability and microstructural evolution. However, due to the stringent requirement of the state-of-the-art, non-uniform original grain structure of the metal ingot comprising large columnar grains growth in the direction of solidification, resulting in brittleness, weak grain boundaries, shrinkage, porosity, etc. remain a major bottleneck. This paper proposes a novel metalworking process to overcome this challenge. In particular, a one-stand hot tandem rolling mill that can break the grain structure and destroy the boundaries having uniform grain structures is developed. The proposed one-stand hot tandem rolling mill was constructed using 60 mm diameter work rolls, 150 mm diameter backup rolls, 120 mm diameter spur gears, a 3 hp electric motor, and a 50 mm diameter shaft. The components were installed, and the roll was fixed at a roll gap of 60 mm. Experimental investigations using a 65 mm aluminium sheet metal at a draft of 5 mm per pass after heating the metal sheet above its re-crystallization temperature were performed to validate the superiority of the proposed model. Available results indicate a robust improvement in the toughness, strength, and resistance of materials. Specifically, the results showed an efficiency of 86 % at an average draft of 4.3mm per pass.

Procedure to implement shear evolution in fast rolling models with online capability on the example of an aluminum flat rolling process

The rolling process induces a heterogeneous deformation over the rolling stock height. The causes are the frictional shear stress between the contacting surfaces and the roll gap geometry. They induce a complex material flow within the rolling stock describable by the shear evolution. The shear evolution has a significant impact on rolling values like grain size and crystallographic texture and therefore on the final material properties of the rolled product. Industry and academia use fast rolling models for flat rolling processes to predict the material properties due to their short computation time. The time advantage enables online applicability to adapt processes in real time or to evaluate the influence of different process conditions several times within seconds. However, these models have a limitation regarding the shear evolution. They do not consider all relevant influences or apply simplifying assumptions, valid only for specific rolling cases. This work presents a general approach to extend fast rolling models to consider the shear evolution without any restrictions to specific rolling cases. The approach derives the shear evolution as shear angle alpha evolution based on FE simulations. The shear angle alpha is a geometrical description and not influenced by rotations, which occur during the rolling process. This enables an enhanced and simple analysis of the material flow. The outcome is an extended model that completely describes the deformation along a deformation path and enables the calculation of each desired deformation value (strain, deformation gradient, velocity gradient, etc.).

Shifting strategy optimization of the thermal work roll in hot strip rolling based on three particle swarms and differential evolution algorithm

ABSTRACT During fast-paced rolling of the same type strip of hot tandem rolling, the thermal expansion of the work rolls has a significant influence on the shape of the on-load roll gap, which needs to be considered in the free shifting of the work rolls. In this paper, the thermal crown evaluation index and the thermal expansion simulation model of the work roll are established, and the influence of different roll shifting parameters on the thermal crown of the roll in the service cycle of the work roll is analyzed. A special roll shifting strategy of the downstream stand is designed, and intelligent optimization is carried out with the goal of thermal roll shape and uniform wear of work rolls. The optimized roll shifting strategy can significantly improve the strip shape quality.

PSIX-7 Sorghum Silage: Effects of Processing on Performance of Backgrounding Beef Cattle

Abstract The aim of the experiment was to evaluate the effect of processing sorghum silage (SS) at harvest, on ADG, DMI and FE of beef heifers. We used 96 Angus heifers in a completely randomized design with 6 pens of 8 heifers per treatment. Mixed model of SAS was used, and the model included the fixed effect of treatment [SS processed (PRO) or not (NPR)] with initial BW used as covariate. Significance was declared at P< 0.05. A dual-purpose sorghum (ADV2450IG, Advanta seeds, Irving, TX) was harvested (Claas Jaguar 930, Harsewinkel, Germany) at the late drought stage of grain maturity and PRO or NPR were obtained with a specific SS cracker (196 mm rolls of 125 teeth each, 40% speed differential, 1.1 mm roll gap). Each treatment was chopped at 15 mm theoretical length of cut and ensiled in polyethylene ag-bags (60 m long and 2.74 m diameter), for 45 d until starting the feeding trial. Two backgrounding diets containing (DM basis), 91.5% SS PRO or NPR (31.4±1.4% grain content on average), 6.5% soybean meal (expeller) and 3% supplement (ROC90, Provimi, Argentina); were offered for a 15 d of adaptation and 60 d of experimental period. Diets were adjusted daily to score 0.5, using the SDSU 4-point bunk scoring system and samples were taken for analyses (Rock River Laboratories, Argentina). Initial, middle and final BW was measured, while DMI was calculated from differences between DM offered and refused, within each pen. In conclusion, harvesting SS using a sorghum-specific cracker led to a 15 and 21% increase in ADG and FE, respectively, when SS was included in diets fed to backgrounding Angus heifers.

PSVI-18 Effect of Processing Method and Severity for Hybrid Fall rye on dry Matter Intake, Ruminal Fermentation, and Apparent Total Tract Nutrient Digestibility in Ruminally Cannulated Beef Heifers

Abstract This study evaluated the effect of processing method and severity of hybrid fall rye on dry matter intake (DMI), ruminal fermentation, and apparent total tract nutrient digestibility for beef cattle. Ruminally cannulated Simmental heifers (n = 8; 327±33 kg) were used in a replicated 4×4 Latin square (21-d periods) balanced for carry-over effects with a 2×2 factorial treatment. Tempered rye [water added to achieve 80% dry matter (DM)] was compared with dry-rolled rye. Roller gap width of 1.23-mm and 0.8-mm were used for coarse and finely processed rye, respectively. This resulted in processing index values of: 80.9% for dry-rolled and coarse; 72.7% for dry-rolled and fine; 92.9% for tempered and coarse; and 88.2% for tempered and fine processed rye. Diets (DM basis) included hybrid rye grain (86%), barley silage (15%), mineral (6%), and dry distillers’ grain plus solubles (3%). Feeding tempered rye increased (P< 0.01) DMI by 0.87 kg compared with dry-rolled rye, and feeding coarse rye increased (P=0.04) DMI by 0.33 kg compared with fine rye. Cattle fed dry-rolled and finely processed rye had greater (P< 0.04) area that pH was < 5.5 compared with tempered and coarse rye, respectively. Ruminal short-chain fatty acid concentrations and ammonia were not affected (P≥0.12). Feeding dry-rolled rye increased DM digestibility by 2.4% (P=0.02), and crude protein digestibility in 3.0% (P=0.01) compared with tempered rye. Starch digestibility was not affected by processing severity of dry-rolled rye, but increased from 92.8 to 95.9% for tempered rye with increasing severity (interaction, P=0.03). Rolling tempered rye at the same roller gap as dry-rolled rye decreases processing severity but may allow for a greater severity of processing without marked reductions in DMI and ruminal pH, while achieving similar total tract starch digestibility. When increasing processing severity (81 vs. 73%), dry-rolling hybrid rye may reduce DMI and ruminal pH.

Novel analytical heat source model for cold rolling based on an energy method and unified yield criterion

Accurate calculation of the heat source in the roll gap during the cold rolling process is the basis for a well-designed coolant system, which is particularly important for reducing roll wear and improving the flatness quality of strip steel. Although many established numerical models have high precision when calculating the work roll temperature, complex modeling processes and large calculation times result in the inability to predict the work roll temperature quickly for the application of automatic control systems. Therefore, the authors developed a new analytical heat source model to calculate the axial temperature distribution of the work roll in the cold rolling process. First, according to the deformation characteristics of strip cold rolling, the deformation zone is divided into a plastic zone and two elastic zones, and the length of each deformation zone is calculated considering the effect of tension. Then, the friction heat generated in the elastic zone is calculated. Second, new exponential velocity and corresponding strain-rate fields satisfying kinematically admissible conditions are proposed to calculate the deformation heat and friction heat generated in the plastic zone. Finally, the work roll temperature prediction model is established by contemplating the heat source of the roll gap, emulsion heat transfer, air cooling, and contact heat transfer with the intermediate roll. By repeatedly optimizing the weighted coefficient d of intermediate principal shear stress on the yield criterion, the maximum error between the calculated results and the actual measured cold roll temperature data was reduced to 3.1%. The effects of the reduction ratio, rolling speed, and resistance to deformation on the deformation heat and friction heat are discussed, and the variation of temperature field of the work roll with time is analyzed quantitatively.

The Effect of the Thermal Deformation of Casting Roll on Strip Thickness in the Strip Casting Process

Many factors affect the strip thickness in the industrial production process of twin‐roll strip casting, such as pouring temperature, casting speed, cooling capacity, cast‐rolling force, and so on. When the pouring temperature and cooling capacity are specified, the magnitude of the cast‐rolling force is determined by the actual roll gap, which has a significant effect on the thickness, shape, and surface quality of the cast strip. As a result, the actual roll gap size is critical for smooth realization. In the actual casting process, thermal deformation is a direct factor influencing the change in roll gap shape for a given roll gap value. Hence, any factor influencing the thermal deformation indirectly influences the roll gap shape. Thus, the critical factors determining the thermal deformation are simulated and studied in this research, which is integrated with actual production, based on the application and secondary development of ANSYS. The effect law of each process parameter on the thermal deformation of the casting roll is given, and corresponding mathematical models are established. This research lays the foundation for the establishment of the cast strip thickness control model and the realization of online control of strip thickness.

Simulation of the Calendering Process of NMC‐622 Cathodes for Lithium‐Ion Batteries

Calendering is the final step in electrode production during the manufacturing of lithium‐ion batteries. It is a crucial process that significantly influences the electrodes’ mechanical and electrochemical properties and is decisive in defining their volumetric energy density and performance. Herein, a discrete element method modeling approach is proposed to predict the process parameters of the calendering process. In particular, the roll gap width is required for a given target porosity. For this purpose, a particle bed of 9 mm in length is compacted using a roll section enabling a deeper look into the compaction behavior of the microstructure. Six NMC‐622 electrodes with different thicknesses are produced and compacted to different porosities. In the experimental investigation, the roll gap width is set and measured allowing a simulative replica of the process. With the process simulation, the force propagation within the electrode can be observed on a particle level. Furthermore, nanoindentation measurements with NMC‐622 cathodes provide information on the densification behavior of cathodes and support the parameterization of the particle bed. The particle‐based simulation of the compaction process is experimentally validated using nanoindentation measurements on NMC‐622 cathodes.

Research Mechanism of Formation on Transverse Corner Cracks in the Continuous Casting Slab of Peritectic Steel

To figure out the formation mechanism of transverse corner cracks at the inner and outer arc of peritectic steel slab, the metallurgical microscope, scanning electron microscope with energy‐dispersive X‐ray spectroscopy, and electron probe‐X‐ray microanalysis, are used to study cracks. High‐temperature mechanical properties and the stress distribution of the outer arc of the bending section under different roll gap schemes are studied and simulated. The outer arc cracks expand along the grain boundary, while the inner arc cracks not only extend along the grain boundary but also traverse along the grains. The outer arc cracks are mainly generated at the bending section and are formed and expanded along the ferrite film. The inner arc cracks' cracking temperature is higher than the temperature of austenite transformation to ferrite. The third brittle temperature ranges are 650–850 °C, and the transverse corner crack sensitivity zone is 680–837 °C. The inner arc cracks are generated because of the element segregation and low temperature of the corner and then extended at the straightening section, and new cracks exist. The weakened cooling intensity and bending earlier at the bending section help to reduce the equivalent stress on the slab. The optimized experiments are conducted, and the transverse corner cracks are reduced significantly.

Fabrication of Mg/Al Clad Strips by Direct Cladding from Molten Metals

This work describes the fabrication of AZ91D/A5052 clad strips by direct cladding from molten metals using a horizontal twin roll caster. Subsequently, the effects of roll speed, pouring sequence, and solidification length on the AZ91D/A5052 clad strips were investigated. The AZ91D/A5052 clad strips with a thickness of 4.9 mm were successfully cast at a roll speed of 9 m/min and with a 5 mm roll gap. The cladding ratio of AZ91D/A5052 was about 1:1. The single-roll casting results showed that the experimental solidification constants of AZ91D and A5052 were 62 mm/min0.5 and 34 mm/min0.5, respectively. The twin-roll casting results showed that the effect of rolling speed on the surface condition of A5052 was greater than that of AZ91D. In addition, the high melting point A5052 alloy poured into the lower nozzle could solve the remelting problem of the low melting point AZ91D. Moreover, extending the upper solidification distance could reduce the generation of intermetallic compounds. The EDS analysis results showed no voids at the bonding interface, while three intermetallic compound layers were also found at the bonding interface of AZ91D/A5052 strips, namely α-Mg + Mg17Al12, Mg17Al12, and Al3Mg2. This study could be instructive for dissimilar sheet metal bonding.

Temperature of Aluminum Alloy Strip During Casting Using a Vertical Type High Speed Twin Roll Caster

The temperature of a strip cast using a vertical type high-speed twin-roll caster was measured by inserting a k-type thermocouple into the strip. The effects of the roll speed and roll load on the cooling rate and temperature at the roll gap were investigated using two aluminum alloys: A383 and Al–4.8%Mg. The thickness of the thermocouple was 0.1 mm, and the sampling time was 0.01 s. The cooling rate increased and the temperature at the roll bite decreased with decreasing roll speed and increasing roll load. The positions of the liquidus and solidus lines were measured, and the reduction of the thickness of the strip was inferred from the roll gap at the solidus line.

Prediction and Analysis of the Force and Shape Parameters in Variable Gauge Rolling

Variable gauge rolling is a new process to obtain a plate for which the thickness changes continuously by continuously and dynamically adjusting the roll gap upward and downward in the rolling process. This technology is an effective method for producing lightweight, low-cost, and economical plates. However, variable gauge rolling is an unsteady process, and the changes in the force and deformation parameters are complex. In this research, based on the minimum energy theory of the variational principle and considering the characteristics of the roll movement and workpiece deformation comprehensively, the internal plastic deformation, friction, shear and tension powers, and the minimum result of the total power functional in upward and downward rolling are obtained with the first integral and then with a variation of adopting the specific plastic power and strain rate vector inner product. The analytical results of the deformation and force parameters are also established using the variational method. Then the precision of this model is certified using the measured values in a medium plate hot rolling plant and the experimental data for Tailor Rolled Blank rolling. Good agreement is found. Additionally, the variation rule of bite angle, neutral angle, and location neutral points are shown, and the change mechanism of the friction parameter on the stress state effect coefficient is given in variable gauge rolling. This research proposes a new mathematical model for rolling process control that provides a scientific basis and technical support for obtaining an accurate section shape in variable gauge rolling production.

Simulation on the Direct Powder Rolling Process of Cu Powder by Drucker–Prager/Cap Model and Its Experimental Verification

For better clarifying the influence of processing factors on the forming quality of the direct powder rolling (DPR) process, finite element simulation based on the modified Drucker–Prager/Cap (DPC) model was established and the key physical parameters of the powder were confirmed by experimental measurements. Subsequently, the effect of the main factors in the DPR process, viz., powder gradation, rolling speed and rolling gap, on the density and morphology of a green sheet were discussed by using an orthogonal experiment design followed by experimental verification. The influence of DPR parameters on the density of the green sheet is examined by a range analysis, which can reflect the sensitivity of influencing factors to the forming quality of the green sheet. The larger the range value is, the more sensitive the influencing factor is. This suggests that the quality of the green sheet is mainly influenced by particle gradation. The results show that the density of the resulting DPR green sheet with optimal parameters is mainly 7.5~8.0 g/cm3, reaches 80% of the theoretical density, and the mechanical strength can also afford the transferring process of the green sheet for the next sintering craft. The methods for modeling, obtaining physical parameters and the numerical simulation results can be used to guide rapid formation of the metal sheet by using direct powder rolling craft.

Influence of intermediate roll shifting on strip shape in a CVC-6 tandem cold mill based on a 3D multi-stand FE model

Intermediate roll shifting (IRS) is widely used for improving the strip shape in the six-high tandem cold mill, but most related studies are limited to a single stand. To fill the knowledge gap, a three-dimensional (3D) multi-stand elastic–plastic finite element (FE) model was developed for a continuously variable crown (CVC)-6 tandem cold mill using data transfer, which was then validated by industrial experimental results. Based on this FE model, the effects of the IRS on the strip crown, strip flatness, loaded roll gap profile and contact normal stress between rolls at each stand were quantitatively analysed. The results show that from Stand 1 (S1) to Stand 5 (S5), the regulation ability of the IRS on the strip crown shows a decreasing trend, which depends on the strip plastic rigidity; in contrast, the regulation ability on the quadratic flatness experiences an obvious increase from S1 to Stand 4 (S4), then a drop at S5, while the IRS exerts little effect on the quartic flatness and quartic crown of the loaded roll gap. Moreover, the most uniform distribution of contact normal stress emerges at different IRSs from S1 to S5. These findings can contribute to a better understanding of the role of the IRS in controlling the strip shape during tandem cold rolling (TCR).

The Development of Pedestrian Gap Acceptance and Midblock Pedestrian Road Crossing Behavior Utilizing SUMO

While there are several published studies for modelling pedestrian behavior at signalized crossings in SUMO, the behavior of pedestrians crossing a road at a location other than a designated crossing, has not been considered to date. This work looks at how to represent pedestrian agents selecting to cross a road at arbitrary locations along the length of the road. The pedestrian agents utilize a gap acceptance model that represents how a pedestrian decides when to cross a road, based on the frequency and speed of approaching vehicles, while considering the spacing between them. Furthermore, the gap acceptance model allows the pedestrians to choose to cross all lanes in one go, when safe to do so, known as Double Gap or one stage crossing. Alternatively, if an agent is identified as a risk-taker, they may choose to cross lane by lane, sometimes waiting in the middle of the road, known as Rolling Gap or risk-taker crossing behavior. The inclusion of these two crossing behaviors allows for situations where urgency plays an important role in behavioral decision making, such as in emergencies, rush hour or in crowd management events. The outlined pedestrian crossing model is attained by integrating the pedestrian model EXODUS with SUMO, via the TraCI API.

LABORATORY ROLLING MILL 150 STUDY AS AN OBJECT OF AUTOMATION

Experimental studies of the process of rolling lead samples were carried out on a laboratory mill 150. During rolling, the rolling force, the roll gap, and the dimensions of the rolled products before and after rolling were measured. Based on the results of the research, the transmission coefficients were determined, which determine the effect of the thickness of the rolled stock and the roll gap on the thickness of the finished rolled product, the rigidity of the stand and the strip. Imitation of the automated system for stabilizing the thickness of rolled products has been performed. It is shown that these studies can be performed in laboratory work on the study of automation objects.