Rolling Radius Research Articles

Roller design and optimization based on RSM with categoric factors in power spinning of Ni-based superalloy

Power spinning is a single-point high-pressure forming process which is usually studied with ideal regular blank. However, in some cases, the blank adopted in this process is from conventional spinning process with non-uniform wall thickness and springback. Therefore, the forming accuracy cannot be guaranteed because of the irregular blank. In this paper, cone, step, and arc rollers are compared and the length change of deformation zone is calculated to further understand the forming mechanism of different roller shapes. Multi-step process simulation considering conventional spinning and power spinning is established. The influence of roller parameters such as roller nose radius, straightening zone in step roller, and bite angle on the maximum roller force in feeding direction is discussed. In addition, the continuous factors such as installation angle and discrete factor roller shape are studied based on the response surface method (RSM) with categoric factors. The results show that roller shape has a big influence on the workpiece forming quality in power spinning process. Step roller is more suitable for use in this work. The roller nose radius and installation angle have great impacts on the maximum roller force in feeding direction.

Effect of rolling motion with large radius on flow and heat transfer characteristics of supercritical methane in a mini channel

• Rolling results in the violent fluctuation of flow and heat transfer in supercritical methane. • Additional force along the flow direction is the key to affect the flow and heat transfer. • Hysteresis exists in the coupling of rolling, flow fluctuation and temperature fluctuation. • Rolling produces greater fluctuation in the near-wall area than that in the inner center area. The offshore floating storage and regasification unit (FSRU) is developing rapidly as a new type of storage and gasification system for liquefied natural gas (LNG), and the heat transfer and system stability of offshore LNG vaporizers are greatly affected by ocean rolling. To reveal the regular pattern and mechanism of supercritical methane heat transfer performance under ocean motion, this research numerically studied the flow and heat transfer characteristics of supercritical methane in a 1 × 1 × 100 mm mini channel under the additional inertial force by large radius rolling. Based on the non-inertial coordinate system, the normal inertial acceleration, radial inertial acceleration and Coriolis inertial acceleration were considered. Moreover, Nusselt number, degree of fluctuation and friction factor were investigated. The ranges of Reynolds number and Nusselt numbers are 15,000 to 45,000 and 35 to 130 respectively. The results show that the Nusselt number and friction factor violently fluctuate under rolling motion, and the fluctuation period is similar to the rolling period. Besides, the fluctuation degree of Nusselt number is greater than that of friction factor, and the largest fluctuation degree of Nusselt number is 27.9%. The effect of the fluctuation increases with the decrease of the rolling period and the increase of the rolling amplitude. Hysteresis exists in the coupling of rolling, flow fluctuation and temperature fluctuation. In addition, the degree of fluctuation is reduced with the increase of fluid temperature and mass flux. For the effect of rolling, the additional force in the mainstream direction plays a leading role. Besides, the influence of radial force is greater than that of normal force for horizontal flow condition.

Finite Element Study on Forming Metal Sheets with an English Wheel

Because of the application trends of Industry 4.0, small-volume large-variety production becomes the daily life in the manufacturing industry. Techniques to flexibly shape sheet metal parts are therefore more and more inquired. This paper is thus aimed to have a preliminary glimpse at the shaping process made by the English wheel, which is broadly used by craftsmen, via Finite Element Analysis. As a result, the parts shaped by an English wheel with a zigzag path show a curved surface having a homogeneous curvature. The more the impression from the bottom roll onto the sheet metal, the smaller the radius of the bottom roll, and the thinner as well as the more compliant the sheet metal, the larger the curvature of the shaped metal part.

Profile Design of the Grooved Die and Rolling Force Prediction in the Cold Pilger Rolling Process

The objective of this study was to design the die groove profile and predict the rolling force produced when employing the variable curvature rolls and mandrel for manufacturing seamless pipes using the cold pilger rolling process. The parameters of the key process design were the diameter of the initial tube and final product, as well as the feed amount, reduction area, principal deformation zone, and roller radius. The rolling forces during the pilger rolling process were theoretically calculated to enable their prediction, and the characteristics of the cold pilger rolling process were identified. The calculated values were in close agreement with the experimental data. The die groove design is important in the prediction process because the dimensional accuracy of the tubes and the life of the dies are highly dependent on this design. The presented design method can be successfully applied to fulfill this objective. The tube shape and adequate tolerance can be attained by using the proposed design method. The mechanical properties of the pipe are evaluated by calculating the Q factor.

Method for measuring the position of the normal reaction on the vehicle wheel

The paper deals with the study of the reaction positions of the support surface on the vehicle wheels. The problems is that the longitudinal drifts of the normal reaction are not fully described. There is no initial data on the rolling radii in the presence of a moment on the wheel. The existing problem does not allow considering components of the longitudinal drifts of normal reactions. The authors noted that the accuracy of predicting the stability and controllability of the vehicle deteriorates. The way out of this is to search other ways to determine the values of these drifts. In conclusion, the authors admitted dividing the general drift of the normal reaction into three components. The paper proposes a measurement method to determine the existence and numerical value of the third component. This method includes indirectly measuring the normal reaction drift that was implemented on an experimental setup.

Research on the Counter Roller Spinning of Large Thin-walled Cylindrical Parts

The counter roller spinning process is an effective method to form large thin-walled cylindrical parts. By using the internal roller instead of the core mould, may solve the problem of high cost of the mould spinning and the failure of forming large-sized cylindrical parts. In order to study the mechanism of counter roller spinning and break through its precision control technology, the finite element method is used to analyse the effect of pass thinning ratio, feed rates, spinning roller angle and inter spinning roller fillet radius on roundness, straightness and wall thickness difference of spinning parts.

Exploration of polar crane geometric parameters with the use of modern geodetic electronic gauges

The paper presents recent explorations of polar crane parameters with the use of the latest geodetic electronic gauges, instead of conventional devices recommended by normative documents for measuring instruments. A set of basic geometric conditions for polar cranes was specified with required precision, namely: convergence of diagonals at the specified points, inside rolling radius of the wheels, lateral sliding of the wheels, longitudinal sliding of the wheels, position of wheels at a given radius, position of wheels at a given diameter, rolling radius of virtual wheels in small balancers, transverse slippage of bridge virtual wheels in small balancers. All basic parameters are shown not to surpass theoretical (design) parameters. The findings illustrate that the main operational characteristics of the polar crane explored herewith are permissible.

Improving the mathematical stability in the numerical simulation of the vehicle movement with an electronic movement control system

The aim of the study is to determine the influence of the calculated radius type on the calculated parameters of the vehicle movement, equipped with an electronic movement control system. A numerical simulation of the vehicle movement equipped with an electronic movement control system was carried out. Under calculated conditions, there are forces that disrupt the stable and controlled vehicle movement. The studies carried out have shown that in the numerical simulation of the parameters of the vehicle movement, the use of a dynamic radius instead of a rolling radius never affects the calculated values of the vehicle’s longitudinal shifts. In this case, the values of the lateral shifts and the turning angle of the vehicle on a dry hard surface change insignificantly, but there is a significant mathematical instability of the solution. On a wet hard surface, the influence of the calculated radii types on the characteristics of the simulated vehicle movement is preserved, but this influence is less pronounced.

HD-lubricated high-speed small reduction rolling of hard steel strips with elastically deformable work rolls

This research investigates the effects of elastic work rolls on the hydrodynamic (HD)-lubricated high-speed rolling of hard steel strips with a small reduction. An innovative numerical method was established to couple the interactions across deformable rolls, pressurised lubricant and strips undergoing elastoplastic deformation. A dynamic explicit finite element analysis (FEA) was used to obtain the deformed solid bodies while a transient Reynolds equation was utilised to govern the hydrodynamic pressure. A non-linear lubricant shearing stress was integrated in obtaining the interface friction. The analysis demonstrates that the hydrodynamic pressure can be more affected by the yield strength of the metal strip and roll radius for a fixed rolling gap in lubricated strip rolling.

Mesh Force Modelling and Parametric Studies for Compound Oscillatory Roller Reducer

A compound oscillatory roller reducer (CORR) with a first-stage gear transmission and a second-stage oscillatory roller transmission is presented. The transmission principle of oscillatory roller transmission is introduced, and the tooth profile equation of the inner gear is derived. The analytical model of mesh force considering the installation errors and manufacturing errors is proposed. Then, parametric studies considering different errors on the mesh force are conducted. Results show that the design parameters are significant factors for mesh force. The mesh force is reduced by 17% as the eccentricity of disk cam increases from 2.5 mm to 4 mm. When the radius of the movable roller increases from 7 mm to 20 mm, the mesh force decreases by 8%. As the radius of disk cam increases from 125 mm to 170 mm, the mesh force is decreased by 26.5%. For the impacts of errors, the mesh force has a noticeable fluctuation when these errors exist including the manufacturing error of disk cam, the installation error of disk cam and the manufacturing error of movable roller change. The prototype of the reducer is manufactured and preliminary run-in test proved the feasibility of the transmission principle.

Effects of Process Parameters on Surface Straightness of Variable-Section Conical Parts during Hot Power Spinning

How to form high-quality variable-section thin-walled conical parts through power spinning is a key issue for superalloy spinning manufacturing. A study into the hot power spinning deformation law of variable-section thin-walled conical parts and the effects of process parameters on surface straightness of forming quality are delineated in this paper. Through the establishment of finite element (FE) models using the single-factor and orthogonal design of experiments, the effects of four key process parameters on the surface straightness have been investigated and the optimal combination of process parameters have been yielded. These key factors include spinning temperature, roller nose radius, mandrel rotation rate and roller feed ratio. The results of FE simulation have been validated through the comparison of the surface straightness of modeled parts with those measured during a spinning experiment. The results reveal that, among the studied process parameters, the spinning temperature has the greatest influence on the surface straightness, followed by the roller nose radius and mandrel rotation rate, and the roller feed ratio has the least influence on the straightness. Larger mandrel rotation rate, smaller feed ratio and suitable spinning temperature can enhance the surface straightness.

Maximum Admissible Slip of Tractor Wheels without Disturbing the Soil Structure

One of the most important parameters that characterize the traction-coupling properties of a wheeled tractor is its slip. The more tractor’s gross traction exists, the higher its traction-coupling properties are. However, this gross traction should not exceed its maximum possible value, which, in turn out, is to be determined by the maximum permissible slip, δmax. This article provides the equation to calculate this crucial parameter and establishes the dependencies between the tractor’s slip and soil structure coefficient. It was shown that the value of δmax basically depends on such soil characteristics as the bulk deformation coefficient and the coefficient of rolling resistance. Calculations showed that, for the average value of the soil bulk deformation coefficient at 4000 kN·m−3, the average value of rolling resistance coefficient at 0.16, and the ratio value of the maximum permissible soil pressure to the tractor wheel rolling radius at 222 kPa·m−1, the maximum permitted amount slip of the tractor wheels should not exceed 15%. With more slip, the soil structure deteriorates significantly. In this case, its structure coefficient may be less than critical, equal to 0.4.

Analysis of the thermal-force roll profile control ability under different hole structures and slot structures in the RPECT

Roll profile electromagnetic control technology (RPECT) is a control technology for strip flatness based on the flexible control of roll profiles. As the core component, electromagnetic sticks can bulge with induction heating of induction coils. To ensure the integrity of the coil circuit, the surfaces of the electromagnetic sticks need to be provided with slots. Moreover, the inner hole of the electromagnetic control roll is also needed to install the electromagnetic stick in the roll. The structures of the inner hole and slots affect the local structure of the electromagnetic stick and the electromagnetic control roll and then change the roll profile control ability. To research the radial bulging ability, the roundness of bulging, and the composition between the thermal crown and force crown under different holes or slots, a finite element model of circumferential RPECT is established by using the finite element software Marc. After analysis, the results showed that the radial bulging ability and the roundness under the influence of the roll radius were larger than those under the influences of the slot radius and slot amount, and the composition characteristics of the comprehensive roll profile were different under different conditions. Therefore, to achieve accurate roll profile control, the influences of the structures of holes and slots need to be included in the RPECT index.

Vibration Characteristics of Hot Rolling Mill Rolls Based on Elastoplastic Hysteretic Deformation

Based on the analysis of the influence of roll vibration on the elastoplastic deformation state of a workpiece in a rolling process, a dynamic rolling force model with the hysteresis effect is established. Taking the rolling parameters of a 1780 mm hot rolling mill as an example, we analyzed the hysteresis between the dynamic rolling force and the roll vibration displacement by varying the rolling speed, roll radius, entry thickness, front tension, back tension, and strip width. Under the effect of the dynamic rolling force and considering the nonlinear effect between the backup and work rolls as well as the structural constraints on the rolling mill, a hysteretic nonlinear vertical vibration model of a four-high hot rolling mill was established. The amplitude-frequency equations corresponding to 1/2 subharmonic resonance and 1:1 internal resonance of the rolling mill rolls were obtained using a multi-scale approximation method. The amplitude-frequency characteristics of the rolling mill vibration system with different parameters were studied through a numerical simulation. The parametric stiffness and nonlinear stiffness corresponding to the dynamic rolling force were found to have a significant influence on the amplitude of the subharmonic resonance system, the bending degree of the vibration curve, and the size of the resonance region. Moreover, with the change in the parametric stiffness, the internal resonance exhibited an evident jump phenomenon. Finally, the chaotic characteristics of the rolling mill vibration system were studied, and the dynamic behavior of the vibration system was analyzed and verified using a bifurcation diagram, maximum Lyapunov exponent, phase trajectory, and Poincare section. Our research provides a theoretical reference for eliminating and suppressing the chatter in rolling mills subjected to an elastoplastic hysteresis deformation.

The hydrodynamics of self-rolling locomotion driven by the flexible pectoral fins of 3-D bionic dolphin

The novel autonomous rolling performance is realized by the pair of pectoral fins of a three-dimensional(3-D) bionic dolphin in this paper numerically. 3-D Navier–Stokes equations are employed to simulate the viscous fluid around the bionic dolphin. The effect of self-rolling manoeuvrability is explored using the dynamic mesh technology and user-defined function (UDF). By varying the parameter ratios, the interaction of flexible pectoral fins is divided into two motion modes, amplitude differential and frequency differential mode. As the primary driving source, the differential motion of a pair of pectoral fins can effectively provide the rolling torque, and the trajectory of the entire rolling process is approximately the clockwise spiral. The results demonstrate that the rolling angular velocity and driving torque in the steady state can be improved by increasing parameter ratios, and the rolling efficiency can reach the maximum under the optimal parameter ratio. Meanwhile, different parameter ratios do not affect the rolling radius of the self-rolling dolphin. The evolution process around the pair of pectoral fins is shown by the flow structures in self-rolling swimming, reasonably revealing that self-rolling locomotion is produced by the pressure and wake vortices surrounding the pair of pectoral fins, and the wake structures depend primarily on the variation of parameter ratio. It properly turns out that the application of the pair of pectoral fins can realize the self-rolling performance through parameter differential modes.

Use of the kinematic radius in the rolling mechanics of an elastic wheel

The analysis of the physical essence of the kinematic and dynamic radii of the wheel is given. It is stated that the rolling radius of the wheel is a conditional kinematic parameter that characterizes only the rolling mode of the wheel. It is not the shoulder of all longitudinal forces acting on the wheel and should not be used to determine tractive forces, rolling resistance and wheel braking forces. Specific examples are given to illustrate the inappropriateness of using the kinematic radius to determine forces and moments. Keywords: elastic wheel, rolling radius, kinematic radius, dynamic radius, arm of force, traction force, rolling resistance force, braking force, rolling mode

Rolling friction in a 3D printed stringless pendulum

The motion of a billiard ball rolling on a 3D printed stringless pendulum was studied by video analysis. This allows for the measurement of the eigenfrequency as well as the coefficients of viscous drag and rolling friction. The stringless pendulum consisted of two circle sectors with variable distance, such that friction coefficients could be determined as a function of rolling radius. Rolling resistance decreases with increasing rolling radius, but does not follow a simple power law; instead the data suggest an exponential dependence.

Bifurcation analysis of a railway wheelset with nonlinear wheel–rail contact

Stability is a key factor for the operation safety of railway vehicles, while current work employs linearized and simplified wheel/rail contact to study the bifurcation mechanism and assess the stability. To study the stability and bifurcation characters under real nonlinear wheel/rail contact, a fully parameterized nonlinear railway vehicle wheelset model is built. In modeling, the geometry nonlinearities of wheel and rail profiles come from field measurements, including the rolling radius, contact angle, and curvatures, etc. Firstly, four flange force models and their effects on the stability bifurcations are compared. It shows that an exponent fitting is more proper than a quintic polynomial one to simulate the flange and works well without changing the Hopf bifurcation type. Then the effects of each term of the nonlinear geometry of wheel/rail contact on the Hopf bifurcation and limit circle bifurcation are discussed. Both the linear term and nonlinear term of rolling radius have a significant influence on Hopf bifurcation and limit point of circle (LPC) bifurcation. The linear critical speed (Hopf bifurcation point) and the nonlinear critical speed (LPC bifurcation point) changes times while within the calculated range of the linear term of the rolling radius. Its nonlinear term changes the bifurcation type and the nonlinear critical speed almost by half. The linear term of the contact angle and the radius of curvature of the wheel and rail profiles should be taken into consideration since they can change both the bifurcation point and type, while the cubic term can be ignored. Furtherly, the field measured wheel profiles for several running mileages are employed to examine the real geometry nonlinearities and the corresponding Hopf bifurcation behavior. The result shows that a larger suspension stiffness would increase the running stability under wheel wear.

Analysis and manufacturing of bistable metallic profiles

Bistable metal sheets with a coiled transport geometry and an unfolded profile as second stable state, are of great interest as lightweight components. It is well known that a specific distribution of residual stresses is necessary to enable bistable properties. With the help of numerical FE models, the optimal process parameters for production of such sheets are evaluated. Afterwards, incremental bending and roll forming experiments are conducted in order to analyse possible continuous production methods for bistable metallic profiles. Finally, the influence of bending and rolling radii on bistability and profile geometries in stable states are investigated.

Method for Determining the Kinematic Parameters of Longitudinal Pass Rolling

A new generalized method for calculating the rolling radius is developed. It is based on an analysis of the real shape of the neutral line in the deformation zone provided that the workpiece in equilibrium under the forces applied to it. It is established that there can be four characteristic positions of the neutral line within the contact surface between the roll and the workpiece. The particular case where the neutral line lies in a plane parallel to the rolling axis and the calculated rolling radius is effective is considered. The actual and effective rolling radii in the case of plugless rolling of pipes in oval roll passes are calculated and compared. A best-fit formula for correcting the calculated values of the effective rolling radius is obtained.