Roller Geometry Research Articles

Powder Compaction Characteristics and Modeling of Calendering Process for Powder-based Solvent-free Manufacturing of Electrodes for Lithium-ion Batteries

Abstract Powder-based solvent-free manufacturing of electrodes for Li-ion batteries represents an emerging and promising technology in electrode fabrication. This method involves a two-roll powder calendering process, where electrode powder materials are compressed onto a current collector to form electrodes with desired properties. The calendering or compaction of dry powders onto a current collector is a crucial step in solvent-free electrode manufacturing, significantly impacting the microstructures, mechanical properties, and electrochemical performance of the produced electrodes. In this paper, we investigate the compaction characteristics of electrode powders to gain insights into their behavior. A powder-on-current collector calendering model is developed based on Johanson's rolling theory of granular solids. This model enables us to infer the underlying calendering parameters essential for the solvent-free manufacturing of Li-ion batteries. To validate the model, we compare it with experimental calendering results, utilizing measured powder properties and roll design parameters as inputs. This approach offers a comprehensive understanding of the effects of roll geometries, particularly roll diameter, and various equipment design parameters on final electrode properties. Such insights have not been thoroughly explored in the emerging field of solvent-free battery electrode manufacturing, thereby contributing to advancements in this area.

Deep Rolling Techniques: A Comprehensive Review of Process Parameters and Impacts on the Material Properties of Commercial Steels

The proposed review demonstrates the effect of the surface modification process, specifically, deep rolling, on the material surface/near-surface properties of commercial steels. The present research examines the various process parameters involved in deep rolling and their effects on the material properties of AISI 1040 steel. Key parameters such as the rolling force, feed rate, number of passes, and roller geometry are analyzed in detail, considering their influence on residual stress distribution, surface hardness, and microstructural alterations. Additionally, the impact of deep rolling on the fatigue life, wear resistance, and corrosion behavior of AISI 1040 steel is discussed. Engineering components manufactured by AISI 1040 steel can perform better and last longer when deep rolling treatments are optimized with an understanding of how process variables and material responses interact. This review provides critical insights for researchers and practitioners interested in harnessing deep rolling techniques to enhance the mechanical strength and durability of steel components across diverse industrial settings. In summary, the valuable insights provided by this review pave the way for continued advancements in deep rolling techniques, ultimately contributing to the development of more durable, reliable, and high-performance steel components in diverse industrial applications. The establishment of generalized standardizations for the deep rolling process proves unfeasible because of the multitude of controlling parameters and their intricate interactions. Thus, specific optimization studies tailored to the material of interest are imperative for process standardization. The published literature on the characterization of surface and subsurface properties of deep-rolled AISI 1040 steel, as well as process parameter optimization, remains limited. Additionally, numerical, analytical, and statistical studies and the role of ANN are limited compared with experimental work on the deep rolling process.

Geometry and Kinematics of the Mecanum Wheel on a Plane and a Sphere

This article is devoted to a study of the geometry and kinematics of the Mecanum wheels, also known as Ilon wheels or the Swedish wheels. The Mecanum wheels are one of the types of omnidirectional wheels. This property is provided by peripheral rollers whose axes are deviated from the wheel one by 45 degrees. A unified approach to studying the geometry and kinematics of the Mecanum wheels on a plane and on the internal or external surface of a sphere is proposed. Kinematic relations for velocities at the contact point of the wheel and the supporting surface, and angular velocities of the roller relative to the supporting surface are derived. They are necessary to describe the dynamics of the Mecanum systems taking into account forces and moments of contact friction in the presence of slipping. From the continuous contact condition, relations determining the geometry of the wheel rollers on a plane and on the internal or external surface of a sphere are obtained. The geometric relations for the Mecanum wheel rollers could help to adjust the existing shape of the Mecanum wheel rollers of spherical robots and ballbots to improve the conditions of contact between the rollers and the spherical surface. An analytical study of the roller geometry was carried out, and equations of their generatrices were derived. Under the no-slipping condition, expressions for rotational velocities of the wheel and the contacting roller are obtained. They are necessary for analyzing the motion of systems within the framework of nonholonomic models, solving problems of controlling Mecanum systems and improving its accuracy. Using the example of a spherical robot with an internal three-wheeled Mecanum platform, the influence of the rollers on the robot movement was studied at the kinematic level. It has been established that the accuracy of the robot movement is influenced not only by the geometric parameters of the wheels and the number of rollers, but also by the relationship between the components of the platform center velocity and its angular velocity. Results of the numerical simulation of the motion of the spherical robot show a decrease in control accuracy in

Effect of different roller end-flange constructions on the fatigue life of the cylindrical roller bearings: A novel flange deformation formula

This paper performs the fatigue life analysis of the radial Cylindrical Roller Bearings (CRBs) with consideration of various roller end-flange shapes such as toroidal-toroidal, spherical-toroidal, and spherical-conical. A novel formula for each flange contact deformation in cylindrical roller bearing with different roller end-flange geometry including toroidal geometry is developed. Inner ring misalignment angle and radial deflection results obtained from the present study are verified with numerical and experimental results from the literature. The results approach to that of literature when the flange is changed from toroidal geometry to conical geometry. Using formulas developed in the present study, the effect of various roller end-flange geometries on the bearing life is investigated for different external loadings. It is observed that the bearing life increases when the roller end and flange are changed to toroidal geometry.

Multi-Geometry Parameters Optimization of Large-Area Roll-to-Roll Nanoimprint Module Using Grey Relational Analysis and Artificial Neural Network.

Micro- and nanofabrication on polymer substrate is integral to the development of flexible electronic devices, including touch screens, transparent conductive electrodes, organic photovoltaics, batteries, and wearable devices. The demand for flexible and wearable devices has spurred interest in large-area, high-throughput production methods. Roll-to-roll (R2R) nanoimprint lithography (NIL) is a promising technique for producing nano-scale patterns rapidly and continuously. However, bending in a large-scale R2R system can result in non-uniform force distribution during the imprinting process, which reduces pattern quality. This study investigates the effects of R2R imprinting module geometry parameters on force distribution via simulation, using grey relational analysis to identify optimal parameter levels and ANOVA to determine the percentage of each parameter contribution. The study also investigates the length and force ratio on a backup roller used for bending compensation. The simulation results and the artificial neural network (ANN) model enable the prediction of nip pressure and force distribution non-uniformity along the roller, allowing the selection of the optimal roller geometry and force ratio for minimal non-uniformity on a specific R2R system. An experiment was conducted to validate the simulation results and ANN model.

Hardening and Softening Behavior of Caliber-Rolled Wire.

The different behaviors of the mechanical properties of drawn and caliber-rolled wires with applied strain were investigated to determine the appropriate process between wire drawing and caliber rolling with consideration of materials and process conditions. Ferritic, pearlitic, and TWIP steels were drawn and caliber-rolled under the same process conditions. Caliber-rolled wires exhibited a hardening behavior in the early deformation stage and softening behavior in the later deformation stage compared with the drawn wires, regardless of the steel. The hardening behavior of the caliber-rolled wires was explained by the higher strain induced by caliber rolling compared with wire drawing, especially the higher amount of redundant work in caliber-rolled wire. The caliber-rolled wire had approximately 36% higher strain than the drawn wire and approximately 85% higher strain than nominal strain. The softening behavior of the caliber-rolled wire in later deformation stages was related to the Bauschinger effect or low-cycle fatigue effect caused by the roll geometries and loading conditions during caliber rolling. The different intersection points of the tensile strength between drawn and caliber-rolled wires with the steels were attributed to the different strain hardening rates of each steel. Between the options of the caliber rolling and wire drawing processes, the appropriate process should be selected according to the strain hardening rate of the material and the amount of plastic deformation. For instance, when the wires need to deform at high levels, wire drawing is the better process because of the appearance of the Bauschinger effect in caliber-rolled wire.

Layered disturbance rejection path-following control with geometry-based feedforward for unmanned rollers

As a widely used engineering vehicle, drum rollers have a higher degree of freedom in motion than conventional passenger vehicles. The uncertainties, caused by road and vehicle condition variations, introduce severe disturbances in the path-following control of unmanned rollers. In this work, a single-drum roller is considered, for which a composite disturbance rejection controller (CDRC) is proposed for path following. The CDRC comprises a disturbance rejection controller (DRC) and a modified pure pursuit controller (MPPC). The DRC lumps all the discrepancies of the models from the roller as total disturbance, which is estimated by the extended state observer (ESO) and rejected in the feedback control loop. For enhanced performance, MPPC is added as a feedforward controller, which calculates the target articulation angle based on the roller geometry model. Compared with the DRC, the settling time of the CDRC is reduced by 12.3%, and the lateral errors are reduced by 43.1% and 39.9% in the presence of uncertainties in the positioning system and steering motor, respectively, while it still maintains a low computational cost. The proposed controller have been used in 15 unmanned rollers for 2 years, using which over 5 million square meters area has been compacted.

Roller Geometry Optimization in Order to Minimize Unsteady Bulging of Slab Casters

Roller Geometry Optimization in Order to Minimize Unsteady Bulging of Slab Casters

Mechanized spreading of ceramic powder layers for additive manufacturing characterized by transmission x-ray imaging: Influence of powder feedstock and spreading parameters on powder layer density

Spreading of uniform, dense powder layers is a critical requirement for powder bed additive manufacturing (AM) processes, and layer quality is influenced by powder feedstock selection and spreading parameters. In prior work, quantification of powder layer density has required disruption of the powder layer after spreading, or compromise in the precision and/or design of the spreading mechanism compared to actual AM equipment. This work demonstrates the use of a precision, mechanized powder spreading testbed coupled with transmission x-ray imaging for spatially-resolved, non-contact powder layer density measurements. Specifically, the influence of several variables on the spreading of aluminum oxide powders is studied: powder size and shape, spreading tool choice (i.e., blade versus roller), traverse speed and/or rotation rate, and powder dispensing methodology (i.e., piston-fed vs hopper). For coarse powders, the density of layers spread with a roller geometry outperforms a blade geometry, reaching the tapped density for the coarse spherical powder. In addition, spreading with roller counter-rotation increases layer density for fine powders but decreases layer density for coarse powders. Increasing traverse speed or the use of textured rollers results in reduced powder layer density for fine powders. Finally, for fine powders, deposition with a vibrating hopper dispenser instead of a piston-fed mechanism, coupled with spreading by a counter-rotating roller, gives spread layer density equal to the tapped density.

Experimental field study of floater motion effects on a main bearing in a full-scale spar floating wind turbine

In this paper we present a full-scale experimental field study of the effects of floater motion on a main bearing in a 6 MW turbine on a spar-type floating substructure. Floating wind turbines are necessary to access the full offshore wind power potential, but the characteristics of their operation leave a gap with respect to the rapidly developing empirical knowledge on operation of bottom-fixed turbines. Larger wind turbines are one of the most important contributions to reducing cost of energy, but challenge established drivetrain layouts, component size envelopes and analysis methods. We have used fibre optic strain sensor arrays to measure circumferential strain in the stationary ring in a main bearing. Strain data have been analysed in the time domain and the frequency domain and compared with data on environmental loads, floating turbine motion and turbine operation. The results show that the contribution to fluctuating strain from in-plane bending strain is two orders of magnitude larger than that from membrane strain. The fluctuating in-plane bending strain is the result of cyclic differences between blade bending moments, both in and out of the rotor plane, and is driven by wind loads and turbine rotation. The fluctuating membrane strain appears to be the result of both axial load from thrust, because of the bearing and roller geometry, and radial loads on the rotating bearing ring from total out-of-plane bending moments in the three blades. The membrane strain shows a contribution from slow-varying wind forces and floating turbine pitch motion. However, as the total fluctuating strain is dominated by the intrinsic effects of blade bending moments in these turbines, the relative effect of floater motion is very small. Mostly relevant for the intrinsic membrane strain, sum and difference frequencies appear in the measured responses as the result of nonlinear system behaviour. This is an important result with respect to turbine modelling and simulation, where global structural analyses and local drivetrain analyses are frequently decoupled.

A novel transient infrared-thermography based experimental method for the inverse estimation of heat transfer coefficients in rotating bearings

Heat Transfer at moving bearing interfaces is a key parameter for the thermal characterization and design of high precision machine tools and electrical engine systems for e-mobility application. Yet, the majority of experimental approaches use tactile sensors to obtain the required temperature information for the calculation of heat transfer coefficients. However, only a limited amount of sensors can be placed in the investigated system, also including significant measurement uncertainties, long investigation times, and providing only access to local temperature information. To overcome these shortcomings, a novel method is presented, using infrared thermography to obtain transient and spatially resolved temperature information of bearing front surfaces. The recorded temperature data is used in an inverse evaluation algorithm, to determine the heat transfer coefficient, considering for modeling heat conduction as well as convective fluxes due to rotating components. Finally, experimental temperature data and calculated heat transfer coefficients are presented, discussing further the effect of low angular velocities on the heat transfer. It is shown, that this method is capable to detect changes in heat transfer coefficient due to variations in rotational speed which was not possible with existing methods. Concluding, this approach can be used in future work to focus in detail on the influence of different rolling elements, geometry and interstitial media.

Finite element and experimental study of the residual stresses in 2024-T3 Al alloy treated via single toroidal roller burnishing

This article presents the outcomes of finite element (FE) simulations and X-ray stress measurements of residual stresses in high-strength 2024-T3 Al alloy introduced via the single toroidal roller burnishing (STRB) process. In terms of the deforming toroidal roller geometry, STRB is particularly suitable for deep rolling. A 3D FE model was developed using the flow stress concept, and the actual STRB kinematics was simulated to evaluate both hoop and axial residual stresses. The FE model was validated through a comparison of FE and X-ray residual stress distributions. The effects of the burnishing force, feed rate, and number of passes on the residual hoop and axial stresses were studied. It was established that increasing the feed rate leads to a decrease in the residual hoop stresses and an increase in the residual axial stresses. The greater burnishing force increases the compressive zone depth and only slightly increases the surface residual stresses. The FE and X-ray stress analyses confirm the effectiveness of STRB of 2024-T3 Al alloy to introduce significant residual compressive axial and hoop stresses.

Mathematical modeling the process of wire surfacing by the smoothed particle hydrodynamics method

We discuss issues the process of layer-by-layer synthesis of metal products by wire surfacing. A mathematical model of the process has been developed and implemented. The model allows one to calculate the volumetric distributions of temperatures, melt flow rates, pressures, components of heat fluxes density, the shape and dimensions of the molten bath, the shape of the free surface of the molten metal, the shape and dimensions of the weld bead. For this purpose, the main physical processes that affect the formation of the metal product were considered, namely: melting and crystallization of the metal, surface tension, the Marangoni effect and the heat source features. The smoothed particle method was used to implement this model. A number of numerical experiments were carried out using the developed model. Firstly, the model parameters for steel and titanium were identified and verified. After that, calculations were carried out to verify the model itself using the obtained roller geometry. The numerical solution for the deposition of one layer was compared with the full-scale experiment. The error was no more than 5% in any direction. Thus, the efficiency and correctness of the constructed model is shown.

Effect of the roll stud diameter on the capacity of a high-pressure grinding roll using the discrete element method

The high-pressure grinding roll (HPGR) is a type of roller mill that continuously produces particle-bed comminution. Since the capacity of the HPGR is determined by not only operating conditions but also the roll geometry, knowledge of the effectiveness of the roll geometry is still limited. This study investigated the effect of the stud diameter on the capacity of a stud-type HPGR using the discrete element method with a breakage model. To evaluate the effect of a stud diameter, which is placed on a roll surface, simulations were performed for three types of HPGR having 13-, 6-, and 3.75-mm studs. Simulation results show that the working roll gap increased when a smaller stud was used. This suggests that a roll surface with a smaller stud was likely to provide a stronger force. As a consequence, roll back likely occurred when a smaller stud was used because stronger friction acted on the roll surface. Meanwhile, the stud diameter had less effect on throughput and power during grinding. These trends obtained in simulation qualitatively correspond to those obtained in experiments. Consequently, the study demonstrated that simulation adopting the discrete element method with a breakage model can contribute to the investigation of the effect of roll design in an efficient HPGR grinding.

Improving fatigue resistance of railway axles by cold rolling: Process optimisation and new experimental evidences

Cold rolling is a relatively simple process known as a method to increase the surface hardness and the mechanical fatigue resistance of metal components by the introduction of residual compressive stresses. Cold rolling is also particularly convenient as it is applied in the final part of the manufacturing process. Despite the process being quite common in the manufacturing of various mechanical components, very limited information is available about the actual advantages that are achievable on safety critical components like railway axles. This paper focuses on both optimisation of the process parameters adopted on the Lucchini RS and on the advantages that are obtained when a well calibrated process is applied. The process is optimized by an analytical model, validated by means of an extensive number of residual stress measurements using the X-ray Diffraction method, that estimates the residual stress profile that is generated under the surface depending on different parameters (force, roller geometry, roller feed, axle geometry and steel grade). An overview of various advantages, demonstrated by an extended series of experimental full-scale tests, is then shown: an increase in the fatigue limit even in the presence of artificial micro-notches and corrosion fatigue. An analysis of the driving force at the crack tip is able to confirm the experimental evidences.

Optimization Procedure of Roller Elements Geometry with Regard to Durability of Spherical Roller Bearings

The article deals with an optimization procedure of roller elements geometry with regard to durability of spherical roller bearings. The aim of the article is to examine the impact of change of the roller elements inner geometry on durability and reliability of spherical roller bearings; the contact strain along a spherical roller by means of the Finite Element Method at contact points of components of a spherical roller bearing by means of designed 3D parametric models. The most appropriate shape of roller elements inner geometry of a bearing from the standpoint of calculated durability was determined based on results of the contact analyses.

Influence of rolling condition and geometry of tire tread on its wear intensity

Wheel tire wear annually takes hundreds of thousands of rubber tons. In this regard, the issue of reducing this negative phenomenon is urgent, for which it is necessary to know what and how affects tire wear. Factors affecting the wear of elastic wheels can be different: recipe of the rubber compound, the amount of traction (or braking) force in contact with the road, the type of movement is straight or cornering, the installation angles of the wheels (camber and toe-in angles), tire design, driving mode - uniform or with acceleration (braking). In this paper, we consider the influence on tire wear of such parameters as the value of the longitudinal force acting in the contact, the camber and toe-in angles, the radius of the motion trajectory and such a structural parameter as the convexity of the tread. When assessing the wear intensity, as is accepted by most researchers, we proceed from the fact that wear is proportional to the friction power in the contact of two interacting bodies.

New cross-rolling process for joining of hybrid components

The proposed innovative cross-rolling process can be used to form hybrid components like shaft hub connections and electric drive parts. The advantages as well as the challenges are discussed in detail, especially the resulting notch geometry and possible approaches for mitigating adverse effects. While the shaft ideally should be a high strength steel, generally any other metal, ceramic or composite material can be used as a joining partner. This paper will present a numerical analysis of the joining process regarding work roll path and geometry as well as an experimental evaluation of the achievable properties and the resulting transmissible loads.

Roller burnishing of Ti6Al4V under different cooling/lubrication conditions and tool design: effects on surface integrity

The paper presents a deep experimental study on surface modifications induced by roller burnishing process of Ti6Al4V titanium alloy. The experimental campaign has been performed based on a design of experiments at varying lubrication/cooling strategies, roller geometry, coating, and burnishing speed. The overall surface integrity has been analyzed in terms of surface roughness, micro hardness, topography, microstructural changes, and tribological performance. The results allowed to better define the relationships within burnishing process parameters and the surface quality of the final component. In particular, the obtained evidences show that cryogenic cooling conditions and coating tools significantly improve the hardness of the final component while the MQL lubrication leads to superior surface roughness. Overall, the process always improves the wear resistance of the components with optimal results when cryogenic cooling and coated tools are employed. Thus, the outcomes of the extensive experimental campaign allow to define a combination of process parameters leading to improved Ti6Al4V surface quality.

Investigating the motion modes of smooth/rough micro/nanoparticles with circular crowned roller geometry and computing the maximum force

The exact positioning of micro/nanoparticles is essential in the construction of micro/nanoscale structures. Of course, the shape of a particle and the external force application location on it influence the type of behavior exhibited by that particle during its displacement on a surface. In former works, biological and non-biological particles have been modeled as cylindrical or spherical particles, while the shape of many such particles is a combination of these two geometries. In this paper, the driving and displacement of particles with circular crowned roller geometry on a substrate by means of an AFM cantilever tip have been modeled three-dimensionally. For a more realistic modeling of actual particle conditions, the Cooper model has been developed for this geometry and the effects of surface roughness have been incorporated into the model. By using the presented model, the forces applied on particle during the manipulation process, the deformations induced in the AFM cantilever, the rotation center and the maximum force applied on particle can be computed and the motion modes of particle (sliding, rolling, rotating) at the onset of displacement can be predicted. The findings indicate that the critical forces associated with rough particles are smaller than those for smooth particles. Furthermore, the effects of particle dimensions and roughness parameters such as the radius and height of asperities and also the effect of AFM tip location on a particle on its motion modes have been studied and the suitable conditions for creating different motion modes have been discussed.