Rolling Radius Research Articles

Numerical study on heat transfer of two-phase fluid in helical coil pipe under ocean condition

The thermal hydraulic characteristics and heat transfer of two-phase fluid in helical coil once-through steam generator under ocean conditions like rolling and heaving motions are studied numerically. A CFD model is established to analyze the effects of motion parameters like amplitude, period and rolling radius and the heat flux distribution are discussed. The analysis shows that the overall heat transfer decreases under ocean conditions, but the overall deterioration is limited, indicting the helical coil pipe has the stability for ocean conditions. The additional forces like Coriolis, centrifugal and inertial forces introduced by rolling motion are analyzed theoretically and the result shows it detorts the original two main vortexes responsible for high heat transfer due to its spiral geometry, making heat transfer fluctuates up and down periodically near the steady state value. As rolling height increases, the heat transfer is nonlinear due to the competition between Coriolis force and centrifugal and inertial forces. As rolling amplitude increases, the heat transfer variation increases and the local heat transfer deterioration is severely aggravated, indicating high rolling amplitude should be avoided as possible. Increasing rolling period makes heat transfer behavior more approximate to static case as gravity and centrifugal force due to spiral geometry is dominate. Under heaving motion, the overall heat transfer decreases, and increasing heaving amplitude and decreasing period make the fluctuation more severe.

Research on the service life of bearings in the gearbox of rolling mill transmission system under non-steady lubrication state

A rolling bearing plays a key role in the gearbox of the cold rolling mill transmission system. As a result, the degradation and failure of bearings can lead to unplanned shutdowns of the entire rolling mill system. Since on-site cold rolling mills work usually in non-steady lubrication rolling conditions originating form variations of multiple parameters, the uncertainty affecting bearing performance in a cold rolling mill transmission system increases, making it more difficult to assess health status and predict the remaining service life of bearings, Therefore, by establishing a coupling model describing the relationship for the rolling mill and normal /faulty gearboxes under non steady rolling conditions, quantitatively studies the influence of various rolling parameters of a rolling mill on the fatigue service life of bearings in the gearbox of the rolling mill transmission system, and verify the effectiveness of linear cumulative damage theory for bearing fatigue service life through experiments and on-site bearing vibration data. The results indicate that as the thickness of the strip steel inlet, lubricant viscosity, and rolling speed increase, or the thickness of the strip steel outlet and rolling roll radius decrease, the service life of bearings gradually decreases. As the fluctuation amplitude of various rolling parameters in the cold rolling mill increases, the service life of bearings in the gearbox of the rolling mill transmission system gradually shortens. Moreover, when the rolling parameter value or fluctuation amplitude increases to a specific values, the remaining service life of bearings will sharply decrease. Under the same rolling conditions, the service life of bearings in gearboxes with faults decreases more significantly than that in normal gearboxes.

Study on the influence of rolling process parameters on the microscopic plastic deformation of nickel-based superalloy single crystal at atomic scale

Nickel-based superalloy workpieces strengthened by rolling process are widely used in the aviation field. However, there remains a need for further investigation into the influence of rolling parameters on the micro-plastic deformation of nickel-based superalloys. In this study, we establish micro-rolling and analysis models to investigate the impact of rolling parameters on nickel-based superalloy single crystals. We delve into the micro-effects of rolling depth, rolling speed, roller rotation speed, and roller radius. The micro-analysis model elucidates the influence mechanism of rolling parameters on nickel-based superalloy single crystals. The research methods and findings offer a novel microscopic perspective and approach for studying the strengthening of nickel-based superalloys through rolling. Additionally, they provide a microscopic theoretical foundation for optimizing rolling parameters.

Research on Rock-Breaking Characteristics of Cutters and Matching of Cutter Spacing and Penetration for Tunnel Boring Machine

Tunnel boring machine (TBM) tunnel construction in composite strata relies heavily on understanding the rock-breaking characteristics of TBM cutters and optimizing cutter spacing and penetration. Utilizing a full-scale rock rotary cutting machine (RCM), this study conducted rock-breaking tests with disc cutters under varying rolling radii. An analysis of rock debris shape and cutter behavior provided insights into rock-breaking mechanisms. Two main types of rock fragments were identified, with both shear and compression failure observed during cutter–rock interactions. The influence of the rolling radius and cutter spacing on cutter forces was analyzed, along with numerical modeling using the particle flow method. Optimal cutter selection in soft–hard composite strata should prioritize cutter force, with the greatest force required in hard rock. Cutter force increases with penetration, while the force difference between cutters decreases with reduced cutter spacing. These findings offer practical guidance for efficient rock-breaking in composite geological formations during tunnel construction.

9‐1: Invited/Distinguished Paper: Flexible TFT Backplane Development for Extremely Small Bending Radius with Organic ILD and Island TFT Structure

A new flexible low‐temperature polycrystalline silicon thin film transistors (LTPS TFTs) backplane on PI substrate with organic dielectric layer and low‐stress structure of island TFT is proposed. This new extremely low stress backplane is able to withstand 20,000 inward bending cycles at a bending radius of 1mm without any noticeable TFT degradation. After 200,000 bending inward cycles at bending radius of 1 mm, the stability test results show that the change of on‐current is 10.07% for hot carrier instability (HCI) test, the change of threshold voltage ‐0.31V for negative bias thermal instability (NBTI) test, the change of threshold voltage ‐0.24V for hysteresis test, and the breakdown voltage of gate insulator 7.73MV/cm, respectively. The AMOLED display panel manufacured with organic ILD does not show any visible degradation of panel image just after 200K rolling at rolling radius of 4mm or 200K folding at folding radius of 1mm.

Flexible TFT backplane development for extremely small bending radius with organic ILD and novel TFT structures

AbstractA new flexible low‐temperature polycrystalline silicon thin film transistors (LTPS TFTs) on PI substrate with organic ILD layer, island TFT, and TFT channel perpendicular to stress direction was proposed. AMOLED display panel manufactured with organic ILD did not show any visible degradation of panel image after outward rolling cycles of 200,000 at rolling radius of 4 mm or inward folding cycles of 200,000 at folding radius of 1 mm. Another novel structure of TFT with channel perpendicular to stress direction significantly reduced change of threshold voltage of −0.03 V compared with change of threshold voltage of −0.6 V for TFT with channel parallel to stress direction for reliability test of high drain current (HDC) after 100,000 outward‐bending cycles at bending radius of 3 mm. After inward‐bending cycles of 200,000 at bending radius of 1 mm, reliability test results for TFT device with organic ILD layer showed that change of on‐current is 10.07% for hot carrier instability (HCI) test, change of threshold voltage −0.31 V for negative bias thermal instability (NBTI) test, change of threshold voltage −0.24 V for hysteresis test, and breakdown voltage of gate insulator 7.73 MV/cm, respectively, and these performances are similar to those of TFT device with inorganic ILD (SiNx).

Energy loss comparison between kinematically equivalent mechanisms: Slider-crank and eccentric cam

The reduction of energy consumption in industrial processes is a challenge to be confronted within the framework of the United Nations’ Sustainable Development Goals. The present study compares the energy loss per cycle of two kinematically equivalent mechanisms: a slider-crank and an eccentric cam with a translational roller follower. We use the work-energy theorem to evaluate energy losses by using a viscous friction model in a stationary regime. The innovation of this study lies in the energetic comparison to identify the best and worst alternatives by analyzing the contribution of their main geometrical parameters, such as crank length, rod-crank length ratio, roller radius and follower offset. The aim is to provide guidelines to help machinery designers to take relevant preliminary decisions that affect energy efficiency. Herein, we include analytical models, numerical simulations and experimental results using a test stand that can be adapted to other planar one degree-of-freedom mechanisms. In this context, we conclude that an eccentric cam mechanism with a big roller radius and no offset provides the best energetic efficiency among the aforementioned mechanisms.

The Optimal Design of the Press Roller to Improve the Winding Molding Quality of Heat Insulation.

In the heat insulation winding molding process of solid rocket motors, the pressure applied by the press roller directly affects the quality of the winding molding. Insufficient pressure can result in poor bonding quality and may cause defects. This paper aims to provide an optimal design of the press roller to improve the winding molding quality of the heat insulation. The effect of the cylindrical press roller on the pressure distribution was analyzed using the elastic foundation model and a finite element (FE) model, which was assessed by Hertz theory. Subsequently, the press roller was optimized to an elliptical concave design. The effect of the radius of the elliptical concave press roller on the pressure distribution was analyzed. A comparison of the effect of the elliptical concave press roller and the cylindrical press roller on the pressure distribution was conducted using the FE model. The results show pressure uniformity is significantly improved when the elliptical concave press roller is employed on the mandrel with the smallest radius. Additionally, the elliptical concave press roller increases the pressure at the edge of the tape, which reduces the risk of lifted edges and, thereby, improves the winding molding quality of the heat insulation.

THREE-DIMENSIONAL MODEL OF EQUIVALENT ROLL GAP OF CVC MILL UNDER CONDITIONS OF ROLL CROSSING AND NO LOAD

Traditional roll technologies focus solely on the contour of the roll gap at the outlet under ideal conditions. However, upon roll crossing, the three-dimensional distribution of the deformation zone becomes asymmetrical, leading to an adverse impact on the rolling pressure in the deformation zone. To study the screw-down load deviation of plate mills, it is necessary to accurately calculate the equivalent three-dimensional roll gap in the deformation zone under roll-crossing conditions. In this paper a model for calculating the equivalent three-dimensional roll gap under the conditions of roll crossing and no load was established based on the method of the coordinate nonlinear transformation of the spatial rectangular coordinate system. Based on this model, the influences of roll-crossing angles and translation parameters on the symmetry of the equivalent three-dimensional roll gap were analyzed. The distribution of the three-dimensional equivalent roll gap was calculated with different roll lengths, roll radii, and the roll gap’s nominal thickness. The intuitive contour map reveals that under the same condition of crossing angle and translation parameters, the larger the roll length and roll radii and the smaller the roll gap’s nominal thickness are, the greater the influence of the roll crossing on the asymmetrical distribution of roll gap is. It put forward a quantitative calculation method for evaluating the symmetrical distribution of the roll gap, and the calculation results can provide the equivalent roll profile for the roll-deformation model.

Estimation of vehicle tire effective rolling radius and vertical wheel/road contact force

In a vehicle, knowledge of physical wheel/road contact parameters is valuable for the design of dynamic control and active safety systems. In this paper, a new method is designed to estimate the effective rolling radius and the vertical wheel/road contact force using an extended Kalman filter and the Pacejka magic formula. Moreover, it allows the estimation of the longitudinal force, the rolling resistance force, and the longitudinal slip. The method is designed in four blocks. First, a comparison with other research is carried out to validate both the controller and quarter-vehicle model blocks. Then, the blocks of the extended Kalman filter and the Pacejka magic formula are applied to estimate all parameters. The relative mean estimation errors are calculated, and the results show that the developed method is capable of estimating all parameters simultaneously and in real-time with satisfactory accuracy.

Оцінка ресурсу фрикційних поверхонь гальмівних дискових механізмів за показниками відносного зношення для легкових автомобілів

Modern development of vehicle designs requires paying great attention to braking properties, which will depend on the design parameters of the brake mechanisms. The article discusses a scheme where a disc brake is installed on the front wheels, and drum brakes are installed on the rear wheels. From the diagram of the distribution of forces that act on the vehicle during braking, the maximum friction forces for the front and rear axles were determined. A general formula was obtained for the braking distance of a vehicle, during which wear of the brake mechanism occurs. We used the results of the well-known theory of friction and wear by I.V. Kragelsky. The mathematical wear model was built for each friction pair. The wear model takes into account the design parameters of the vehicle, the wear resistance coefficient of materials, the initial braking speed of the vehicle, the mileage and braking distance. The main design parameters of the brake system are the friction radius, the kinematic rolling radius of the wheel, and the amount of drive pressure.
 To assess the service life of the brake mechanism, it was proposed to use such an indicator as the relative wear of associated parts. A formula has been obtained for calculating this indicator based on changes in geometric parameters and operating modes of the brake mechanism under operating conditions. A forecast was made of the service life of the brake mechanisms of the front and rear axles of passenger cars, which is proposed to be carried out according to the indicator of relative wear of friction surfaces. Graphic dependences of the distribution of relative wear of the friction surfaces of brake mechanisms for Chevrolet Aveo and Forza cars were constructed. It was shown using the example of Chevrolet Aveo passenger cars that the relative wear of the front axle brakes is maximum and it varies from 22.5 to 26.1%, and for the rear axle this figure varies from 21.0 to 22.5%. The service life of the brake disc is 4.44 times greater than the service life of the friction lining for the Chevrolet Aveo. For the Forza car this figure is 4.76. The results of the work can be used to estimate the residual life of brake mechanisms, taking into account operating conditions.

Prediction of Energy Consumption in Horizontal Roughing Process of Hot Rolling Strip Based on TDADE Algorithm

The steel industry is the key industry of energy consumption. The optimization of rolling process parameters is an effective measure to reduce and optimize energy consumption. Accurate energy consumption prediction has an indispensable guiding function in the planning of process parameters. However, the traditional energy consumption prediction and machine learning methods have been unable to fit the needs of high precision and reliability. Taking the horizontal roughing process (HRP) of hot rolling process as the research object, this paper mainly introduces an energy consumption prediction mechanism model (ECPMM) based on a roller adaptive wear strategy by analyzing the strip forming mechanism and rolling process. Then, two directions adaptive differential evolution (TDADE) algorithm is proposed based on a novel adaptive strategy. This algorithm has better convergence speed and global optimization ability than other optimization algorithms in the parameter optimization of ECPMM. We carried out comparative experiments on five machine learning algorithms. The results show that the ECPMM optimized by TDADE is superior to the five machine learning algorithms in prediction accuracy and stability. Finally, we conducted ablation experiments on the energy consumption characteristics of the HRP process, which turns out that using a smaller reduction and roller radius can reduce energy consumption. Summarizing the above experimental results suggests that the ECPMM has high accuracy and robustness, and satisfies the requirements of practical application. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —It is necessary to carry out the deep analysis and research of energy consumption prediction involved in the process planning of strip hot rolling, the inspiration of this article is stem from this point. The commonly used energy consumption prediction methods include mechanism modeling and machine learning, but both have disadvantages, like low prediction accuracy and black box, which must have to be performed to solve by adapting the production demand of high reliability. In this paper, the combination of the mechanism model and data-driven method is used to realize the accurate prediction of energy consumption and improve the reliability of the model. To the best of our knowledge, this is the first paper about the research on energy consumption prediction of hot rolling process based on mechanism model and data-driven, especially in data size, time granularity, algorithm design, and prediction performance. Such research is helpful to guide engineers to design rolling energy consumption. We will dive a bit deeper into learning the energy consumption and process parameters during the rolling process in future studies.

Calculation formulas for contact curves of technological machine

The problem of describing the contact curves of technological machines has been solved. At the same time, contact interaction was studied taking into account changes in the technological parameter and deformation of the materials of the contacting bodies. The obtained dependencies make it possible to find rational parameters of the technological process with sufficient accuracy. The obtained models indicate that the shape of the contact is influenced by such parameters as strip thickness, roll radii, external forces, as well as parameters characterizing the deformations of the contacting bodies.

Leather squeezing efficiency analysis

This paper presents the results of an efficiency analysis on the pressing of leather after dyeing, determined by the residual moisture content of the leather. The study establishes the law of changes in humidity during the leather pressing process. It was found that as the thickness and initial moisture content of the skin decreases, its final moisture content also decreases. An analytical dependence of the residual moisture content of the skin has been derived, which can be used to determine rational parameters for squeezing machines. The results show that reducing the skin thickness and increasing the roller radius lead to a decrease in the residual moisture content of the leather.

Force analysis of roller squeezing mechanism

Force analysis of roller squeezing mechanisms was conducted on the basis of analytical dependencies obtained to determine the energypower parameters of roller squeezing of semi-finished leather products after dyeing. These dependencies were determined taking into account the hydraulic pressure during squeezing. It was revealed that the thickness of the leather layer and the radius of the roll have the greatest influence on the energy-power parameters. With a decrease in the thickness of leather and the radius of the roll, the gripping force can be reduced due to a decrease in the extent of the contact zone. A decrease in the roll radius reduces the torque and power required to rotate the roll.

Calculation of energy-power parameters of roll mechanisms

Calculation formulas for determining the energy-power parameters of roll mechanisms, such as the forces created by the roll gripping devices, the torque, and the power required to rotate the rolls were derived in the study. It was revealed that the radii of the rolls and the thickness of the processed material have the greatest influence on the energy-power parameters. Reducing the roll radius and material thickness makes it possible to reduce the gripping force related to a decrease in the length of the contact zone. As the radius of the roll decreases, the torque decreases as well due to the decrease in the radius of action of the resulting friction force.

ПРОГНОЗИРОВАНИЕ НАГРУЗОЧНЫХ И ЖЕСТКОСТНЫХ ХАРАКТЕРИСТИК ПНЕВМАТИЧЕСКИХ ШИН МЕТОДАМИ КОМПЬЮТЕРНОГО МОДЕЛИРОВАНИЯ

Methods are considered for calculation of load and stiffness characteristics of pneumatic tires of radial and diagonal design, as well as modeling of flat and curvilinear motion of a car wheel with pneumatic tires. The calculated values of load characteristic and radial stiffness of 235/55R17 passenger tire and 46/90R57 all-steel truck tire obtained by finite element modeling in MSC.Marc software package are compared with the results of Biderman model calculation. In a quasi-static setting, the rolling process of the wheel with the 235/55R17 passenger car tire is analyzed in flat motion at a speed of 90 km/h and a rotational speed of 10.1–13.5 Hz. The following load and stiffness characteristics of the tire affecting smooth running, stability and controllability of the wheel are determined: dependence of the rolling radius on torque, circumferential stiffness, dependence of traction with the road surface on the amount of slip, coefficient of slip resistance, dependencies of lateral force and stabilizing torque on the angle of lateral skid.

Process Parameters Optimization of One-Step Spin Forming of Top Cover with Center Flanged Hole

To assist the low-cost manufacturing of tanks, a one-step method of marginal-restraint mandrel-free spin forming is therefore proposed in this study for the forming of top covers with flanged holes. With the finite element simulation analysis, three different forming strategies are discussed, and the best spinning process is identified. The proposed forming strategies involve preforming the flanged surface first and then preforming the spherical and flanged surfaces in a subsequent trajectory and is proved to have better forming accuracy. Furthermore, the forming quality of the spun parts is improved and optimized by employing more passes, smaller feed ratios, and larger roller fillet radii. It was experimentally verified that the marginal-restraint mandrel-free spinning one-step method with five passes, a feed ratio of 1 mm/r, and a roller fillet radius of 60 mm for the cylindrical roller can achieve accurate forming of a top cover with a center flange hole.

Theoretical modeling and transmission characteristics analysis of a novel double-roller hourglass worm drive based on enveloping principle

Traditional planar double-enveloping hourglass worm pairs have the characteristics such as the strong bearing capacity, high transmission efficiency and long life-span. However, the high relative sliding velocity and the serious agglutination or abrasion may also occur at the contact point on tooth surfaces. In this paper, a novel type of double-roller hourglass worm pair is proposed and analyzed, wherein, the worm part adopts from the planar double-enveloping worm pair, the corresponding meshing tooth surface of worm gear is replaced by two rows of cylinder rollers for reducing friction and enhancing meshing efficiency. That is, the original meshing tooth surfaces in worm gear are replaced by the common tangent plane of rollers to form a special type of meshing drive, the original line-contact form between tooth surfaces was changed to point-contact so that the sliding friction was transformed into rolling friction, and the meshing efficiency can be greatly improved. The theoretical model of double-roller hourglass worm pair was established based on spatial enveloping principle, the meshing equation and tooth surface equations were derived. The solid models of worm and gear were established and assembled. The parameters of enveloping surface angle, roller radius and friction coefficient, which affecting relative motion velocity at meshing contact point and efficiency during the whole transmission process was analyzed and discussed systematically. The results showed that comparing to the traditional worm pair, the roller’s rotation greatly reduced the relative sliding velocity and improved meshing efficiency at the contact point in this double-roller hourglass worm pair.

Theoretical analysis and a parametric study on forced vibration of large statically deformed curved beam with rigid links and moving support

Forced vibration characteristics around large statically deformed configuration of curved beam system with rigid links and moving support are analyzed. In addition, the paper also investigates various parametric effects of height to span ratio and roller radius to height ratio coupled with support connection mechanism and profile shape, on dynamic characteristics of the curved beam system. The subject problem includes two interrelated problems: determining deformed configuration under static load and dynamic response of the loaded beam under harmonic excitation. The static problem is analyzed incrementally through the variational principle-based energy method in body-embedded curvilinear frame considering geometric nonlinearities due to combined bending-stretching and non-uniform initial curvature. In each incremental step, the nonlinear governing equation is solved iteratively, and kinematic constraints due to interactive deformation of the flexible curved beam with rigid links are imposed to obtain the global solution. Concerning the statically deformed configuration, governing equation for forced vibration is derived through Hamilton’s principle in curvilinear frame. Nonlinear effects caused by combined bending-stretching modes of vibration, non-uniform curvature, and lumped mass of the dead static load are considered. The set of inhomogeneous governing equations is solved through Broyden’s method. A direct substitution technique through successive relaxation is also employed to obtain an initial guess solution. Besides the forced vibration, free vibration analysis at static deformed configuration is also carried out for the completeness of the study. The theoretical model is validated through comparisons of loaded natural frequency results with finite element package. After the validation study, the effects of the mentioned geometric parameters on the dynamic response of the curved beam system are investigated and presented suitably. The physically insightful framework along with the parametric study may facilitate simulation and design of several practical structures involving moving support and rigid links subjected to continuous excitation around large statically deformed configurations.