Radial Rolling Research Articles

Research the Dimensional Accuracy of C45 Steel Ring Forgings Produced by Radial Rolling.

The rolling process of rings is a commonly used method for producing annular forgings. There are two primary types of this process: radial-axial rolling and radial rolling. This article presents the research results regarding the latter, in which obtaining a product with the assumed dimensions constitutes a major problem. In industrial practice, the process parameters are based on the experience of technologists and/or by trial and error. This is why the authors considered it justified to undertake the research aimed at determining the influence of the main process parameters, that is, preform temperature and tool speed, on the shape and dimensions of the cross-section, which determine the internal and external diameters of the rolled ring. The research was based on numerical simulations and experimental studies. The results obtained proved that the higher the feed speed of the main roll, the greater the change in the cross-sectional height during rolling, and the smaller the cross-sectional deformation (the so-called fishtail). Nevertheless, a higher preform temperature reduces the final height of the ring and reduces cross-section deformation. On the basis of the obtained test results, guidelines for the process design were postulated, considering the influence of temperature and speed parameters on the final dimensions of the forging and the dimensions of the preform.

Fatigue Life Analysis of Remanufactured Radial Rolling Bearing with the Replaced Loading Zone

The replacement of the loading zone is not considered in the active calculation method on fatigue life of remanufactured bearings. In practical application, when the radial bearings are reinstalled after remanufacturing, it is required to replace the loading zone, which results in a large deviation between the calculated fatigue life according to the active calculation method and the actual life. In this paper, the fatigue life factors of radial bearings with different remanufacturing levels are calculated according to the actual application condition. The results of case studies show that with the improvement of the remanufacturing level, regardless of whether the loading zone is replaced or not, the remanufacturing bearing life factor is gradually increased and the maximum can reach 1. Considering the replacement of the loading zone, the life factors of remanufactured bearings with different fixed rings are also very different, among which the remanufacturing deviation of fixed outer-ring level II is the largest, reaching 11.3%. However, with the increase of the remanufacturing level, the deviation decreases gradually. The life factors by the method presented in this paper of remanufactured radial bearings with the replaced loading zone are significantly higher than those of the active calculation method. The research results of this paper provides a more accurate calculation scheme for the fatigue life of remanufactured radial rolling bearings, which is a supplement to the active calculation method and has important practical significance for the practice of bearing remanufacturing engineering.

A novel method for ball forming by cross wedge rolling

In this paper, a novel method for ball forming by cross wedge rolling (CWR) was proposed, and the finite element (FE) simulation and experimental verification were carried out with the 26 mm diameter steel ball as an example. First of all, the die parameters including spreading angle β and forming angle α were selected and the 3D models of the die and guide plate were designed. Then, the FE model was established and preliminary simulation was carried out using the Simufact 16.0 software. The preliminary simulation results showed that the pushing empty defect occurred in the process due to lack of transition from spreading stage to sizing stage and conical die section. Modifying the die design by adopting the method of adding transition spreading angle θ and forming angle α´ increasing with the increase of rolling depth to, the defect could be eliminated and the full filling can be obtained. In addition, the simulation analysis after modified also included effective strain and stress distribution, the kinematic analysis of metal flow, the damage distribution based on the Cockcroft-Latham criterion, the temperature evolution and force parameters in the CWR process. Finally, the rolling experiments and radial rolling force testing experiments were carried out to verify the numerical results. The results indicated that the FE simulation results were consistent with the experimental results through quantitative analysis, which proved that the novel method for ball forming by CWR was feasible simultaneously.

Influence of symmetric/asymmetric boundaries on axisymmetric convection in a cylindrical enclosure in the presence of a weak vertical throughflow

The linear and nonlinear stability of axisymmetric convection of a viscous fluid in a cylindrical enclosure heated from below is investigated for various radius to height ratios. A weak vertical throughflow is imposed in a gravity-aligned or a gravity-opposing manner. Symmetric and asymmetric boundaries of free-free, rigid-rigid and rigid-free types are considered for lower and upper boundaries with isothermal temperature boundary condition. The side-walls are assumed to be rigid and adiabatic. A convergent Maclaurin series representation is considered for the finding of axial trial eigenfunctions. In order to corroborate the results of the present study with those of a previous investigation, the critical Rayleigh number and the number of radial rolls manifesting for any given aspect ratio are determined in the case of no throughflow and an exact match is found. Further, the influence of boundaries and the effect of throughflow on chaotic and periodic regimes of motion are studied with the help of a time series solution and the largest Lyapunov exponent as indicators of chaos. The novelty of the present study is the use of a Maclaurin series representation for the eigenfunctions of the linear problem and using the same in determining the solution with the convective mode.

Influence of Diameter Increase Speed on Diameter-Axial Rolling of Large 40Cr13 Stainless Steel Ring

Rolling speed ratios during the rolling process are critical to ring forming in this pepper. The selected roll feed mode is constant with the increasing speed of ring diameter during the main rolling stage. Based on Deform-3D finite element software, a large size ring with a diameter of φ1530 mm was taken as the research object. The numerical model of a large 40Cr13 stainless steel ring is established. The radial-axial rolling process of rings under different diameter increase speeds was simulated, and the changes in radial rolling force, temperature, and strain distribution of rings after rolling were analyzed under different diameter increase speeds. The results show that under the same conditions as other parameters, increasing the ring diameter increase speed has less effect on the temperature and equivalent standard deviation of variation inside the ring after rolling, but has more effect on the external surface, and both SDP and SDT decrease with the increase of ring diameter increase speed. The ring diameter increase speed on the maximum rolling force is more obvious, with the diameter increasing speed increasing. Using the rolling force, temperature standard deviation, and equivalent effect variation standard deviation as reference indexes, the diameter increase rate suitable for 40Cr13 rings is 6 mm/s.

A Novel Set-Up for In Situ Measurement and Mapping of Lubricant Film Thickness in a Model Rolling Bearing Using Interferometry and Ratiometric Fluorescence Imaging

This paper describes a unique experimental set-up constructed for studies of lubricant behaviour in an operating rolling element bearing including in situ quantitative measurements of film thickness in and around the element-raceway contact. The set-up is based on a deep groove ball bearing in which the outer race is made of sapphire to allow full optical access to the zone in which the rolling elements are loaded against it. This allows direct imaging of lubricant films under both steady-state and transient conditions and at contact pressures and rotational speeds representative of those present in real rolling element bearings. Optical interferometry is used to measure thin EHL films inside the ball–raceway contacts while a specific laser induced fluorescence approach, referred to as ratiometric fluorescence, is implemented to observe the lubricant distribution and quantify its thickness ahead of the ball–raceway contact. Results are presented to validate the accuracy of the method and to investigate the influence of bulk lubricant viscosity and bearing speed on contact film thickness, inlet starvation and lubricant distribution around the ball–raceway contact. To the best of our knowledge, the work described here is the first to directly measure lubricant distribution and EHL film thickness in a ball–raceway contact in an operating radial rolling bearing.Graphical

Bonding mechanism and preparation process of titanium/iron composite thin sheet by non-vacuum rolling

As a new type of layered metal composite sheet, titanium/iron composite thin sheet has attracted much attention because it can meet the dual requirements of the environment and material properties. This paper reports a non-vacuum rolling method that is more suitable for preparing titanium/iron composite thin sheet in industrial production. Herein, the bonding mechanism of the layered metal composite sheet was elucidated by analyzing the forces on the sheets during the non-vacuum rolling process then it was applied to explain the influence mechanism of the rolling reduction rate on interfacial bonding properties. The titanium/iron composite thin sheet was prepared by non-vacuum rolling with a 65% rolling reduction rate, and the interfacial microstructure was studied to verify the accuracy of theoretical judgments. The results show that a shear deformation zone exists at the interface of the layered metal composite sheet in the rolling process. In this zone, the oxide film on the interface breaks, and the exposed fresh metal undergoes metallurgical bonding under the action of radial rolling force to form a composite interface. With the increase of rolling reduction rate, the range of the shear deformation zone expands, and the radial rolling force acting on the interface increase, which is the main reason for the improvement of the rolling reduction rate on the bonding effect. Shear deformation caused vast dislocations in the interface microstructure of composite sheet. The texture of the titanium layer has a certain width under the action of shear deformation. The texture of the iron layer is mainly α-fiber, caused by shear deformation. Moreover, broken oxide films and diffusion layers of titanium and iron elements were observed at the interface.

Rotordynamics of an Improved Face-Grinding Spindle: Rotational Stiffness of Thrust Bearing Increases Radial Stiffness of Spindle

Abstract The support is a key factor affecting performance of face-grinding spindle. However, advantage of traditional rolling element bearing is not highlighted when it is for large-size face grinding. This technical brief aims to develop a combined support for the face-grinding spindle consisting of a water-lubricated hydrostatic thrust bearing and two types of radial rolling bearings, and the flexible rotor dynamics of the spindle with the combined support is analyzed using the modified transfer matrix method. The results show that the rotational stiffness of water-lubricated hydrostatic thrust bearing can increase the radial stiffness of the face-grinding spindle, so the small-size rolling bearings can be utilized as the radial support for the spindle by aid of such rotational stiffness. A comparative study of comprehensive performance between the spindle supported by rolling bearings and the replacement spindle designed with our proposed combined support shows that the proposed one has technical advantage of large axial load-carrying capacity, low frictional power loss, low temperature rise, etc.

Research of the Tool Velocity and Product Shape Aspects of the Hot Radial Rolling of C45 Steel Rings

Research of the Tool Velocity and Product Shape Aspects of the Hot Radial Rolling of C45 Steel Rings

Manufacturing large shafts by a novel flexible skew rolling process

When manufacturing large shafts with multi-specification and small-batch production, both the conventional forging and rolling process bring a high tooling cost due to heavy forging press or large-sized specialized roller. In this study, a novel flexible skew rolling (FSR) process is proposed by adding degrees of freedom to the rollers as compared to the typical skew rolling process. Since each of the FSR rollers has three degrees of freedom (circle rotating, radial rotating, and radial feeding), the FSR process can be divided into four stages: radial rolling, rollers inclining, skew rolling, and rollers leveling. Therefore, the FSR process can produce various shafts with the same rollers via programming different movements. To verify the feasibility of FSR process, a physical investigation corresponding with a numerical simulation for a single-step shaft is undertaken with a Φ80 × 390 mm C45 steel billet. According to the results from physical experiments and numerical simulations, the FSR formed shaft has a maximum deviation of 0.99 mm, and its microstructure and properties have been improved obviously. Moreover, although there is a tendency of the center crack in FSR products as predicted by numerical results, both the transverse and longitudinal sections of the physical shaft are free from central cracking. The major forming defects that existed on the rolled shaft are knurled pockmarks, surface threads, and side cavity, which are the typical defects of the conventional skew rolling and cross-wedge rolling and can be removed by machining. To the authors’ knowledge, this novel process has a good combination of flexible production and less loading, which will be of great engineering significance to reduce the tooling cost in large shafts manufacturing.

Early Weak Fault Diagnosis of Rolling Bearings Based on Fiber Bragg Grating Sensing Monitoring

Aiming at the problems of weak dynamic response and difficulty in diagnosis of early damage of rolling bearings, a diagnosis method for early damage of rolling bearings is proposed. Taking radial rolling bearings as the main research object, the load symmetric structure of deep groove ball bearings is analyzed. Based on the mechanical second-order system theory, the sensor monitoring structure is constructed. The generalized resonance principle is used to identify weak signals, and the fiber Bragg grating is used for signal sensing. The signal is obtained through the fiber Bragg grating high-speed demodulator. When a continuous periodic generalized resonance wave appears in the amplitude–frequency analysis of the signal, and there is a high-frequency resonance frequency, it can be proved that the bearing is faulty. The diagnosis method can effectively avoid the interference of low-frequency signals, the frequency spectrum is pure and there is no electromagnetic interference. It fully shows that the fiber Bragg grating sensor is suitable for the monitoring and diagnosis of the early weak fault of the bearing.

Numerical investigation of the radial cold rolling process of the grooves

The radial cold rolling process is widely used in industry due to the advantages of chip removing processing. In this study, circular complex profiles were formed by cold-rolling with radial feed, using a patented device with two roller-tools. By achieving several numerical simulations of the radial rolling process, the study aimed to establish the influence that the maximum set force and the diameter of the workpiece have on the productivity of the process and the quality of the formed trapezoidal and metric grooves. The numerical simulations were performed with ABAQUS/Explicit software and by using a previously validated finite element model. The penetration curve of the roller-tools in the material was introduced in the simulation as an analytical function and was determined based on experimental researches. To express the dependency of the penetration curve coefficients on other rolling conditions, a multivariable analysis using a design of experiments technique was performed. The parameters that result from numerical simulations and were analyzed in this study are the profile forming time, the maximum radial force, the distribution of the equivalent strains in the axial section of the profiles, and the profile dimensions. The conclusions that were drawn from the analysis of the results regarding the influence of the set maximum force and the workpiece diameter on the analyzed parameters of the numerical simulations, together with the definition of efficient process criteria, allowed also the identification of the optimal conditions of the rolling process.

EFFECTS OF DESIGN PARAMETERS ON STATIC EQUIVALENT STRESS OF RADIAL ROLLING BEARINGS

The aim of this study is to theoretically investigate the effects of design parameters on the static equivalent stress of radial rolling bearings, such as the point contact case for ball bearings and line contact case for roller bearings. The contact pressure, contact area and von Misses stress of bearings are calculated based on geometrical parameters, material parameters and loading parameters by using the developed MATLAB program. To achieve this aim, both the maximum contact pressure pmax and Von Mises effective stress σVM are simulated with respect to design parameters such as varying ball and roller element diameters and varying ball and roller element elasticity modulus. For the point contact case and line contact case, it was concluded that increasing the diameter of ball and roller elements results in reducing the maximum contact pressure pmax Furthermore, increasing the elasticity modulus of the ball and roller elements results in increasing the maximum contact pressure σVM. Furthermore, increasing the elasticity modulus of the ball and roller element results in increasing the maximum contact pressure pmax and Von Mises effective stress σVM because of the decrease of contact area A. The determination of the diameter of the ball and roller elements and the selection of material are crucial and play an effective role during the design process. Therefore, bearing designers and manufacturers should make the bearing geometrical dimensions as large as possible and bearing material as elastic as possible. Furthermore, the stress-based static failure theory can also be used instead of the standard static load carrying capacity calculation. Moreover, Von Mises stress theory is also compatible with the finite element method.

Study on the metal flow behaviour of deformation areas of large ring radial-axial rolling process

Ring radial-axial rolling technology is the best method to produce high quality large seamless ring. The metal flow behaviour of deformation areas of large ring radial-axial rolling process is studied. It is found that the fishtail pit of up-down surface of the ring section arises after the section passes through radial rolling area and that of in-out surface of the ring section arises after the section passes through axial rolling area. In order to gain better ring section, single radial rolling process is needed to remove the fishtail pit of in-out surface after double radial-axial rolling process. The study is very useful to constitute the process scheme of large ring radial-axial rolling.

Observation of Tribological Wear on PEEK Shaft with Artificial Defect under Radial Rolling Sliding Point Contact

This paper’s aim is to develop the tribological repair method in PEEK (Poly-ether-ether-ketone) polymer mechanical parts with surface damage. The radial rolling sliding contact tests were carried out by using a machined PEEK shaft with an artificial defect as surface damage. An alumina ball and a PTFE composite pin contacted a PEEK shaft specimen under cyclic compressive stress with friction. The particle as solid lubricant from a PTFE composite pin filled up the crevice of the artificial defect. After that, the artificial defect was covered with the deformed microgrooves on the PEEK shaft surface. Due to adhesion by compressive stress and friction, the crevice of the artificial defect was closed. In a running-in process, the artificial defect could be reduced by the adhesion repair.

Investigation of bond formation behaviour in composite ring rolling

Ring rolling is an incremental bulk metal forming process used to produce seamless rings with a wide variety of sizes as well as processible materials. Combining the principle of roll bonding and ring rolling could enable production of seamless composite rings with different materials on the inside and outside, therefore giving the opportunity to manufacture rings tailored to specific applications. A fundamental condition to achieve this is a stronger growth tendency of the inner ring compared to the outer ring, which is satisfied at respective forming temperature by choosing a material combination of a stainless steel outer ring and a tempering steel inner ring. A closed-loop controlled Finite Element ring rolling model is used in conjunction with a contact interaction subroutine for modelling generation and rupture of local material bonds by implementation of an empiric model for bond generation. Efforts to prevent oxidation of the joining surface for ring rolling trials were successful but did not lead to a lasting material bond after rolling. A lasting material bond between both rings was only achieved after adjusting the process strategy to initially allow free lateral spread of the rings in the radial roll gap without reduction to the original ring height in the axial roll gap. FE simulations provided the crucial hints for this adjustment, as they were able to show repeated bond formation and rupture during the process as well as the impact of the adjustment on the combined stress state between both rings.

Surface layer microhardness and roughness after applying a vibroburnishing process

The ball vibroburnishing process of external cylindrical surfaces involves workpiece rotation, while a ball is being pressed and forced to roll on the cylindrical surface, simultaneously, achieving an axial vibration. Experimental research was designed in accordance with the principles of a full factorial experiment with six independent variables at two levels on the test pieces made of two distinct steels, the medium-carbon steel 1C45 and the low-carbon alloy steel 18CrMn4-4. The frequency and amplitude of the vibration motion, ball diameter, radial rolling force, workpiece peripheral speed, and feed rate were considered as process input factors. The process output parameters were the surface roughness parameter Ra, Vickers microhardness of the surface layer measured at a certain distance from the hardened surface, and the hardened layer thickness. Through mathematical processing of the experimental results, power type functions were determined as empirical models. Worth mentioning is the fact that significant influence is exerted by the vibration amplitude on the size of the surface roughness parameter Ra, as well as the vibration motion frequency on the surface layer Vickers microhardness.

Three-Dimensional Numerical Simulation on Thermocapillary Convection of Moderate Prandtl Number Fluid in an Annular Shallow Pool with Surface Heat Dissipation

In order to understand the effect of surface heat dissipation on thermocapillary convection of moderate Prandtl number fluid in an annular shallow pool, we performed a series of three-dimensional numerical simulations by using the finite volume method. An annular shallow pool is full of 0.65cSt silicone oil with Prandtl number of 6.7. The radius ratio and the aspect ratio of the pool are respectively fixed at 0.5 and 0.1. Surface heat dissipation Biot number is varied from 0 to 50. Results indicate that the critical Marangoni number of flow destabilization mainly depends on the coupling effect of the thermocapillary force and surface heat dissipation on the free surface, which decreases first, and then increases gradually. When Biot number is small, the steady axisymmetric flow after the flow destabilization will bifurcate to the hydrothermal wave. With the increase of Marangoni number, the flow pattern evolution at a small Biot number is similar to that of an adiabatic free surface, and the fundamental oscillatory frequency increases gradually. With the increase of Biot number, the radial roll cells near the outer cylindrical wall gradually extend to the inner wall, and eventually occupy the whole liquid pool. When Biot number is large, the flow pattern after the flow destabilization is a radial rolling cell pattern with alternating azimuthal direction. Then it gradually evolves into azimuthal waves, and the fundamental oscillatory frequency has a slight decrease.

Математическое моделирование процессов радиального нагружения и качения колеса с безвоздушной шиной

Математическое моделирование процессов радиального нагружения и качения колеса с безвоздушной шиной

Localized Radial Roll Patterns in Higher Space Dimensions

Localized roll patterns are structures that exhibit a spatially periodic profile in their center. When following such patterns in a system parameter in one space dimension, the length of the spatial interval over which these patterns resemble a periodic profile stays either bounded, in which case branches form closed bounded curves ("isolas"), or the length increases to infinity so that branches are unbounded in function space ("snaking"). In two space dimensions, numerical computations show that branches of localized rolls exhibit a more complicated structure in which both isolas and snaking occur. In this paper, we analyse the structure of branches of localized radial roll solutions in dimension 1+$\varepsilon$, with $0<\varepsilon\ll1$, through a perturbation analysis. Our analysis sheds light on some of the features visible in the planar case.