Rolling Radius Research Articles

Effect of the elastic deformation of rolls on the surface texture transfer in skin-pass rolling

This paper investigates the surface texture transfer with elastically deformed work rolls in skin-pass rolling. A numerical approach was developed to efficiently overcome the multiscale challenges associated with the numerical characterisations. To couple the microscale plastic deformation of strip surface asperities with the microscale elastic deformation of roll surface asperities, a specific method was first developed to generate the characteristics between normal contact pressure and interface separation. To deal with the three-dimensional deterministic rough surfaces, a material redistribution scheme was used to predict the plastic deformation of the strip surface asperities and a discrete fast Fourier transform algorithm was employed to efficiently calculate the elastic deflection of the roll surface asperities. These enabled the subsequent multiscale analysis in coupling the microscale interface contact with the macroscale deformation of the metal strip and work roll. As such, the stick/slip transition in the rolling bite due to the elastic deformation of the roll as well as the surface topography of the rolled strip have been quantified. The new method has successfully revealed the effects of elastic roll deformation, roll radius, and strip thickness/roughness on the resultant surface texture of strips in skin-pass rolling.

Tension modeling and precise tension control of roll-to-roll system for flexible electronics

This study proposes the design of a roll-to-roll system for flexible electronics that enables accurate and precise tension control. It analyzes the factors for change in the tension of a roll-to-roll system and develops a tension model for each section to successfully predict the tension that is applied to such a system, the sagging of film according to tension, and deformation due to residual stress. This series of modeling processes allow engineers to design a roll-to-roll system for flexible electronics. Both a velocity control method for the tension between in-feeder and out-feeder—where there is no change of roller radius—and torque control method for the tension in modules like the rewinder, where the roll radius changes, are proposed. A roll-to-roll system according to the proposed design procedure and tension control methods was manufactured and experimented on under various test conditions. The accuracy and precision of velocity control between the in-feeder and the out-feeder were 100.01% and 1.15%, respectively, whereas those of torque control between the out-feeder and the rewinder were 99.9% and 1.35%, respectively, both at one sigma. The experiments confirmed that the two proposed types of tension control methods were accurate and precise. The experimental result with a monitoring sensor showed that the modeling was valid and that an accurate roll-to-roll system minimizing tension reduction was built. This study successfully demonstrated roll-to-roll system design and control techniques that are applicable to various pieces of roll-to-roll process equipment.

Numerical Analysis and Investigation on the Drawbending Springbackand Fracture

In this paper, the effect of process parameters on the drawing springbackand fracture mechanism of high strength steel in drawbending process was investigated. The fracture behaviour and fracture morphology were observed and analyzed using Scanning Electron Microscope (SEM). The process parameters studied in this paper includes drawing speed, roll radius, drawing force and roll radius. The springback angle measurement method for drawing springback was also introduced and applied. The conclusions were drawn from the results. The drawbending springback angle increases withthe increase of drawing velocity. The springbackdecreases with the increase of the round roll. The large bending angle leads to the large springback. The large tension force can decrease the springback angle. The springback increases with the increase of the drawing distance. The fracture with theplane angle of 60 indicates a shear fracture and thedominated brittleness mode, which is induced by a large radius against thickness value. The fracture vertical to straight side indicates the ductility tension fracture, which is induced by a small radius against thickness value.

Single Ping Filtering of Multi-Beam Sounding Data Based on Alpha Shapes

AbstractFrom the standpoint of complex marine environments relative to underwater acoustic signal propagation, the application of multi-beam systems for the filtering and processing of multi-beam sounding data is critical. However, currently existing automatic filtering methods estimate data, which involve several calculations and require the respective computer to possess significant processing capabilities. In this study, raw data are measured using an interferometer multi-beam echo sounder, and the characteristics of the noise data are analyzed. The noise data are discontinuous; however, accurate data can be approximated as a continuous distribution. Under the assumption of continuous underwater terrain, in consideration of a circle of the appropriate radius rolling on the terrain profile, the continuous underwater terrain data can be extracted from the raw data by means of the alpha-shapes algorithm. Finally, on the basis of the measured data in a sail trial, the effectiveness of the proposed algorithm is verified.

Кинематический расчет и построение графиков высоты подъема и скорости толкателя тангенциальных кулачков с использованием программы MATHCAD

The article shows the design features of tangential cams with a rounded top, provides a method for determining the lifting height and speed of the pusher when the roller is rolling in a straight line and in contact with the actual profile of the cam. The formulas for the kinematic calculation of the tangential cam are refined taking into account the radius of the initial circumference of the shaft, the radius of the rounding of the cam tip and the value of the radius of the pusher roller. Calculations are given to determine the stroke and speed of the pusher when the roller is rolling on the sections of the straight and arc-shaped surface of tangential cams with a radius of rounding of 6 and 10 mm. Formulas are proposed for determining the lift of the pusher in the rolling section of the roller along the radius of the cam tip at a constant coefficient λ = 1 and λ = 1,5. Using the Mathcad program calculations are performed and combined graphs of the pusher lift and the change in its speed are constructed for two types of tangential cams

An Improved Parallel Inverse Design Method of EMU Wheel Profile from Wheel Flange Wear Viewpoint

An improved parallel inverse design method is proposed for wheel profile optimization. The dominant merit of this method is the ability to automatically search the target performance curve and obtain the optimized profile without artificial experience. With the help of vehicle system dynamic theory, an EMU model has been established in Simpack, and the dynamic performance is calculated with two profiles, i.e., optimization profile and original profile. The contact and mechanical characters are analyzed by Hertz’s theory, Kalker global algorithm, and CONTACT program. It is found that the rolling radius difference (RRD) with the optimization profile is higher than the original one, especially when the lateral displacement is greater than 3 mm. The creep force density with the optimization profile is significant with a wheelset displacement of 6∼9 mm. Compared with the original one, the distribution of contact points with the optimization profile is more uniform, and the contact position is more biased towards the root of the wheel flange. It means the optimization profile can provide higher RRD value and creep force with large lateral displacement, which is beneficial for reducing wheel flange wear. The dynamic simulation indicates that the optimization profile can help reduce the wheel flange force and wheel flange wear in a sharp curve. Meanwhile, the dynamic behaviors and wheel tread wear on a tangent track or a large curved track are also favorable with the optimization profile.

Principles of Wheelset Hunting and Construction of Total Solution to Hunting

Wheelset hunting is a motion with two degrees of freedom. The second degree of freedom of hunting is investigated in this paper. Rolling radius difference is commonly understood as the root cause of wheelset hunting. Normally, hunting will begin as soon as the truck begins to move. Rolling radius difference will initiate the hunting and can only be used to determine the configuration of the first quarter of a hunting cycle. Then a mechanism will come into exist to determine the configuration of the second quarter of the hunting cycle, which is exactly the same as the one of first quarter but in the opposite direction. The second half of the hunting cycle is a mirror of the first half. The information from wheelset hunting is too large and too complicated for people to understand and analyze. However, the radius of curvature of wheelset circular motion can be calculated exactly, especially at some special configurations, even though the radius of curvature of wheelset circular motion keeps changing in both magnitude and direction. Furthermore, comparison of the radii of curvature between hunting curve and a cosine curve shows that the curve for the wheelset in hunting motion is sinusoidal. This is proven mathematically in the paper. The limits in Klingel’s results were discussed. Due to the fact that Klingel’s results are unable to provide a strong theoretical base for further understanding the complicated dynamic characteristics caused by hunting, misleading in hunting is overwhelmed. After understanding the principles of wheelset hunting, three critical speeds in hunting and dynamic loading for truck design in three directions were calculated; wheelset hunting curve while curving was generated; wheelset dynamic interaction was analyzed and the question “Why trains stay on tracks” was answered correctly, just to name a few. Thus, a total solution to the hunting problems can be expected and was discussed in the paper.

High-speed 3D digital image correlation for measuring tire rolling resistance coefficient

A novel method is proposed to measure rolling resistance coefficient of high-speed running tire. Compared with the existing rolling resistance coefficient measurement methods, the new approach is non-contact measurement based on the calculation of relative flexible principal strain rate. A high-speed stereo vision system is utilized to capture the transient deformation of high-speed rolling tire. In order to better understand the full-field dynamic distribution characteristics of high-speed rolling tire, an improved digital image correlation is proposed to accurately measure the relative coupled displacement and the relative flexible deformation. The rolling resistance mechanism of high-speed rolling tire could be clearly observed from the relative flexible principal strain rate distribution. On this basis, the tire rolling radius and rolling offset could be acquired by analyzing the relative displacement distribution and the relative flexible principal strain rate, and then the rolling resistance coefficient of high-speed rolling tire could be calculated. The experimental results demonstrate that it is feasible to measure the resistance coefficient of high-speed rolling tire by using high-speed 3D digital image correlation.

A novel approach for the edge rolling force and dog-bone shape by combination of slip-line and exponent velocity field

This study presents a new mathematical model for edge rolling force and dog-bone shape using the combination of slip-line and exponent velocity field. The slip-line field of the dog-bone area is drawn out based on the deformation characteristics of edge rolling and the maximal depth of dog-bone zone is determined. Then a new exponent velocity field and corresponding strain rate field which satisfy kinematically admissible condition are proposed to analyze the edge rolling force based on upper bound approach. The upper bound solutions of dog-bone shape and rolling force are obtained by minimizing the total power which contains the internal plastic power, frictional and shear powers. The effects of reduction rate, initial thickness and roll radius on dog-bone shape size and edge rolling force are discussed. The results obtained by the combined solution in this paper are compared with measured data in strip hot rolling field and finite element method (FEM) simulation results, and a good agreement is found.

Theoretical and experimental evaluation of no-slip feeding condition in ECAP-Conform of a square-section metallic rod

This study addresses the applicability of the equal channel angular pressing–Conform (ECAP-Conform) process, which is recently used to obtain the fine-grained structure via severe plastic deformation (SPD). A novel theoretical method based on preventing the deformed rod from slipping on the feeder roll called slip threshold criterion (STC) was presented. Firstly, the total required torque was calculated by combining the energy balance and the upper bound methods. The amount of the minimum roll-contact angle was specified so that no slip happened between the rod and the roll. The STC was achieved in terms of the roll radius, roll-contact angle, raw material strength, and frictional condition between the rod and the tooling. To validate the analytical model, the ECAP-Conform process for a square cross-section rod of grade 2 commercially pure titanium was performed, and the reactive torque was measured empirically then compared with the analytically calculated value. It was found that there is a reasonable agreement between the theoretical model and the experimental outcome (an error of less than 11%). The results revealed that the performance of the process improves by increasing the roll-contact angle, roll friction, and roll radius, as well as decreasing the friction of the segment and die surfaces.

Study on asymmetrical cold rolling considered sticking friction

A new model considered the sticking friction for analyzing the asymmetrical cold rolling process is proposed by the slab method. This friction model is composed of the Coulomb friction model and yield shear stress. The analytical models of the rolling pressure are given respectively based on Coulomb friction model, constant friction model and Orowan friction model to compare the effects of different friction models on the friction stress and rolling pressure. The proposed model can avoid the problems of the friction stress exce eding the yield shear stress in Coulomb model and the friction factor m>1in the mixed friction model. The influences of the rolling parameters on the friction stress and the proportion of the sticking zone in the deformation zone are analyzed. The results show that the proportion of the sticking zone increases with the increases of the reduction rate, friction coefficient and roll radius, and decreases with the increases of the roll speed ratio and tensions. The calculated values by the proposed model agree well with the experimental results.

Determination of pin-roller parameters and evaluation of the uniformity of granular fertilizer application metering devices in precision farming

The application of fertilizer to the soil for the subsequent extraction by plants is a method to increase crop production. Fertilizer spreaders with an outer groove wheel (OGWFSs) have a large volume, and current metering devices are suitable for precision farming systems. However, the study of OGWFSs has shown that fertilizer metering is impaired due to sudden releases of fertilizer batches. Research has shown the performance advantage of using a pin-roller metering device whose pins are configured in the form of a truncated pyramid. This configuration not only provides highly uniform fertilizer discharge but is also advantageous for use with wet fertilizers and prevents clogging. In this study, an orifice was added between the pins to increase the working volume of the metering device and the amount of fertilizer discharge. The uniform distribution of the fertilizer particles and the amount of fertilizer discharge depends on the pin parameters. Therefore, the objective of this study was to determine the pin-roller parameters to increase the uniformity of the distribution and the amount of discharged fertilizer for variable-rate fertilizer applications. The pin-roller configurations that were investigated included the α angle, height of the roller pin, β angle, and radius between two pins for six right and left entry lines. As a preliminary test, 25 pin-roller configurations were designed and evaluated for fertilizer distribution at three rotation speeds of the metering device. The uniformity of the fertilizer distribution was evaluated in a laboratory test, and the coefficient of variation was used as an evaluation index. A compound fertilizer, N-P2O5-K2O, was used in the experiment. The results indicated that different pin-roller characteristics of the metering device had significant effects on the uniformity of the distribution and discharge capacity of the fertilizer. Based on the results of the preliminary test, a new pin-roller design was developed. The performance of this pin-roller was evaluated and compared to that of the OGWFS. The coefficient of variation and the amount of discharged fertilizer was evaluated at three different rotational speeds. The discharge capacity of the new pin-roller was not as high as that of the OGWFS at all rotation speeds of the metering device, but the coefficient of variation was higher for the pin-roller than the OGWFS at lower speeds. However, there was no significant difference in the coefficient of variation between the metering devices at higher speeds.

Experimental study on effects of vehicle speed variations on effective rolling radius according to the changes in tire pressure

This study aims to experimentally examine the effects of vehicle speed changes on the vertical resonance frequency of effective rolling radius variations for applying to TPMS (Tire Pressure Monitoring System). For this, the road tests have been conducted at constant vehicle speeds 30, 60, 90km/h for tire pressures 15, 20, 25, 30, 35psi. In these tests, the effective rolling radius changes have been measured. Test results show that the vehicle speed changes cause the resonance frequency to shift at same tire pressure. Therefore, this study shows that the changes in vertical resonance frequency resulting from vehicle speed changes may cause wrong tire pressure information to be taken by TPMS.

Prediction of Longitudinal Curvature Radius of 3D Surface Based on Quadratic Relationship between Strain and Coordinates in Continuous Roll Forming

Continuous roll forming (CRF) is a new method for the rapid forming of three-dimensional (3D) surfaces developed in recent years, and the significant advantage of CRF compared with traditional die forming is that the longitudinal dimension of the sheet metal is not limited. By controlling the curvature radius and gap shape of upper and lower bending rolls, three-dimensional parts with different shapes and sizes can be precisely formed. When the elastic deformation is ignored during the forming process, the transversal curvature radius of the three-dimensional surface is consistent with the radius of the roll gap centerline. Therefore, the calculation of longitudinal curvature radius is the key to improve the accuracy of the 3D surface in CRF. In this paper, the basic principle of CRF is described. The modified formulas for calculating the longitudinal curvature radius of convex and saddle surfaces based on the quadratic relationship between the strain and coordinates are deduced in detail, and the corresponding design method of the roll gap is derived. Furthermore, the mathematical equations of convex and saddle surfaces are given. Through numerical simulation and theoretical analysis, it is found that the relative errors of the longitudinal centerline radius are reduced from 13.67% before modification to 4.35% after modification for a convex surface and 6.81% to 0.41% for a saddle surface when the transversal curvature radius is 800 mm and the compression ratio is 5%. The experimental and measured results indicate that the shapes of formed parts are more consistent with the target parts after modification, which further proves the applicability of the modified formulas.

Prediction and analysis of cold rolling mill vibration based on a data-driven method

Mill chatter is one of the most common problems in cold rolling. Thus, it is important to investigate the mill chatter phenomenon to ensure a high-speed and stable rolling process. The traditional mill chatter mechanism model cannot meet the monitoring and rapid diagnosis needs of the rolling process in the field. In this paper, a data-driven mill vibration analysis method is proposed. The main objective of this study was to develop a mill vibration monitoring method and an intelligent algorithm for mill chatter early warning. Rolling experiments showed that the proposed monitoring method could be a promising and effective technique for assessing the chatter phenomenon. The mill vibration acceleration amplitude prediction performance of a support vector regression, neural-network-based method, and extreme gradient boosting method were evaluated. The results proved that the prediction performances of the proposed extreme gradient boosting method were highly reliable with the highest determination coefficient value of 0.779, lowest mean absolute percentage error of 9.7%, and better forecast robustness under all of the dataset ratios. Meanwhile, the contribution rates of the variables on the mill vibrations were investigated, and results showed that an effective way to eliminate the mill chatter was to control the rolling speed, cumulative rolling strip length, tension and roll radius.

ANALYSIS OF RAIL-WHEEL INTERACTION IN CURVES WITH SMALL RADII

Purpose. The authors goal is to point out that the new geometric design of the curves of tramways is recommended, furthermore the introduction of a new parameter too. This new parameter is the Creepage Index (CI), which takes into consideration the values of wheel creep from the optimal rolling radii difference on every wheelset in the bogie. Methodology. The several types of railprofiles and railway wheel tread profile geometres have been analised with a special softver and compared with standards, TSIs and BOStrab. Findings. The result of the analisys is that the mechanical conformity of rail/wheel interaction (running characteristic) in tramway tracks are unfavourable and new regulations are necessary to reduce the rail/wheel wear and corrugation especially in curves with small radii. Originality. In the EU the Technical Specifications for Interoperability (TSI) are in force, which regulate the parameters of running behaviour for the international and national public railways. However, the regulation does not apply to domestic tramways. In the course of the analysis, the author propose to introduce a system of regulation, which based on the mechanical suitability of the rail/wheel interaction. This is especially justified, because for example the regulation of German light rails (BOStrab) only requires the geometric dimensions of the wheel and the groove of the rail and their limits. Practical value. The author developed new geometric design and limit systems of narrow curves and straight tracks and a new test parameter, which shows degree of coherence for running characteristic of the given curve and vehicle, from the aspect of infrastructure, in case of all wheelsets of bogie. This CI (Creepage Index) parameter takes into account all wheel creep values resulting from the variations (+, –) of the optimum rolling radius difference. This results the tightening of bogie design principles and for running characteristic reasons, it requires the continous flange running of the outer wheel in narrow curves.

Measurement of Wheel Radius in an Automated Guided Vehicle

In the case of automated guided vehicles using odometry, a very important issue is to know the actual rolling radius of the wheel used to calculate the position of the vehicle. This radius is not constant. Its changes depend on the elastic deformation of the band layer and wheel slip. The theoretical determination of the value of the radius and the nature of the change is very difficult. For this reason, it was decided to determine the rolling radii by the experimental method. For this purpose, an appropriate test stand was built and the proposed research method was checked. Within the tests, there was also obtained a number of interesting results characterizing the material used to build bands and the ranges of changes rolling radii for the tested material were specified.

Development and application of a calculation method for the equivalent conicity in high-speed turnout Zones

ABSTRACT Equivalent conicity is an equivalent mean parameter for reflecting the effects of lateral wheel-rail forces on passenger comfort on trains. Based on the asymmetry of the variable cross-section rails in the turnout zone, this paper views the equivalent conicity of a wheelset in the turnout zone as an equivalent conicity of a wheelset in which the wheels match all constant-section asymmetrical rails. A calculation method is established for the equivalent conicity of the turnout zone according to the hunting motion wavelength formula of wheelsets; considering the Rolling Radius Difference (RRD) curve of several ‘zero-crossings’, the principle of minimum gravitational stiffness is used as reference for determining the point ye at which the equivalent conicity of a large lateral displacement is calculated. For fluctuating RRD, the equivalent conicity is calculated using the zoning method; the paper also proposes to evaluate wheel-rail contact geometry in the turnout zone based on the nominal equivalent conicity of the most probable lateral displacement of the wheelsets. Using the matching of wheelsets of different service lengths and the No.18 turnout switch zone as an example, this paper studies the effects of a changing wheel profile on the equivalent conicity of the turnout zone.

84‐2: Study on Reliability for Impact and Rolling of Film Stacks in Rollable AMOLED Display by Finite Element Analysis

In this study, the film stacks of rollable AMOLED display are analyzed and designed by FEA (finite element analysis). The control for the layer thicknesses and stiffness of film stacks are two of the key designs for rollable AMOLED display. Also, the use of OCA (optically clear adhesives) brings a particular effect to the setting of neutral plane. In the FEA, constitutive model of hyperelasticity is chosen to describe the mechanical behavior of adhesives since the nonlinear elastic behavior and large deformation characteristics of adhesives. A 7.4‐inch WQHD prototype rollable AMOLED display has been successfully rolled up more than 15,000 cycles in dynamic at 10mm rolling radius without damages.

Wheel profile optimisation for mitigating flange wear on metro wheels and verification through wear prediction

Metro trains often encounter the problem of wheel flange wear when they pass through sharp curves, especially for the poor wheel–rail profile matching or lack of lubrication, evidently increasing the maintenance and replacement costs for wheelsets and rails. Based on the field investigation and numerical simulation, the cause of severe flange wear of the original S1002 wheel profile on a Chinese metro line is analysed. An optimised wheel profile is proposed according to the rolling radius difference (RRD) for improving vehicle curving performance and mitigating wheel flange wear. A wheel wear prediction model is developed by combining the metro vehicle dynamics model considering multipoint contact with the long-term wear simulation model, and then validated with the field measurement results. The performance of the optimised wheel profile is evaluated numerically. The results indicate that the root cause of the wheel flange wear is the improper matching of wheel and rail profiles. The optimised wheel profile generally proves to perform better in terms of wheel–rail contact geometry, mechanical properties, vehicle running stability, curving negotiation and wear performance. The wheel flange thickness loss of the optimised wheel profile is decreased by 55.7% compared with that of S1002 profile.