Roller Profile Research Articles

Non-Newtonian Starved Thermal-Elastohydrodynamic Lubrication of Finite Line Contacts

Heavily loaded finite line contacts working under elastohydrodynamic lubrication (EHL) conditions are quite often found in machine elements. However, a perfect line contact requires absolute alignment of the axes of the contacting bodies, which is difficult to achieve. In order to overcome this problem and avoid edge loading, one or both of the contacting cylinders are crowned. This article presents a new model for finite length line contacts. In addition to the finite length of the contact and the profile of the contact bodies, the proposed model takes into account the thermal effects, non-Newtonian lubricant behavior, and starved lubrication. The governing equations are solved using the multilevel multigrid technique. The results were validated by comparing film shape and pressure distribution of a finite line contact against an infinite one. The influence of the lubricant starvation and fillet radius on the pressure distribution, film shape, temperature distribution, and friction coefficient are presented. Finally, the effect of alternative roller profiles is shown.

Study on Roller Profile for Cam Forming by Cross Wedge Rolling

Based on the motion relation between rollers and work piece during cross wedge rolling (CWR) process, roller profile equations for cam forming were studied. A three-dimensional entity model of the roller was established using the profile equations. Process of cam forming by CWR was simulated by DEFORM-3D. The FEM data was used to analyze dimensional accuracy of the formed cam. Results demonstrate that the equations can be used in roller design for cam rolling.

Roller Profile Development for an Axially Loaded, Single Row Spherical Roller Bearing in an Oscillating Application

Abstract Typically it is not recommended to use a single row spherical roller bearing in an application in which there are significant axial loads. The use of these bearings in a less than optimal customer application can be driven by the need for a high load capacity within a limited geometric envelope. Specialized roller profiles can be developed that eliminate high contact stresses on the roller ends that can lead to the premature failure of the bearing. In this paper, analytical results are presented for the roller to raceway contact stress of four different roller profiles with a given load applied to the bearing. The profiles considered are single transverse radius, double transverse radii, and optimized symmetric and asymmetric. The piecewise logarithmic profiles developed are applied to a barrel roller in this paper, but a generalized method is developed such that the profile could be applied to any type of roller—cylindrical, barrel, hourglass, or tapered. The analysis results for two of the profiles are validated by dynamic testing performed within RBC’s Corporate Test Laboratory on a three axis, hydraulic, computer controlled test rig. The bearing inner ring is oscillated while the bearing is subjected to simultaneous radial and axial loads. The control software allows the monitoring of radial displacement and bearing torque during testing. The test results correlate very well with the analytical results. The displacement and torque readouts are shown to predict the onset of raceway fatigue and spalling for one of the roller configurations before testing is complete and the bearing is disassembled.

Design and Simulation of the Drill Groove Squeegee Roller's Profile

Based on the method of vector analysis, the mathematical model of squeegee roller for twist drill groove was setup. At the same time, the parameter design and simulation software for the profile curve of drill groove squeegee roller was developed with Visual C++ Language. The simulation results showed that the mathematical model of squeegee roller was right, and the design accuracy and efficiency of the twist drill squeegee roller was improved greatly.

Cold rolling on textured rollers to obtain regulated surface roughness

At OAO MMK, a new production technology has been developed for cold-rolled steel sheet with regulated surface roughness, used in the auto industry. This technology relies on regulation of the tension in the cold-rolling mills, a special textured barrel surface of the working rollers, new roller profiles, and the use of a wetting liquid in the temper mill.

Stress Analysis of the Skewed-Roller Slipping Clutch Based on Frictional Contact and Dynamic Equilibrium

As a novel power transmission component, the skewed–roller slipping clutch (SRSC) produces resisting torque depending on relative rotation and sliding between askew arranged cylindrical rollers and specially curved races. In this paper, the surface contact stress and von Mises stress between the rollers and the races are calculated and the effects of roller profile modification on reducing stress concentration are investigated under frictional contact and dynamic equilibrium of the rollers and races.

The Effect of Roller Profile Modification on Roller Bearing Performance

According to roller profile modification method, several commonly used modified rollers were selected into the bearing dynamic analysis combined with dynamic model of bearing. As the three types of modified roller an example, simulation program was established to analyze the load distribution of loaded roller under the working conditions of upright loading and offset loading of bearing, respectively. The effects of modified roller on bearing dynamic parameters were discussed. The results provided optimal direction for bearing selection and design under different working conditions.

Surface plastic deformation distribution and microstructural evolution in the compound rolling of Ti–50Al billet

Compound rolling, which uses two different roller profiles to create plastic strain variation in the surface of a material, is described in this study. Based on the local load theory, equipment for the plastic deformation on the surface of the rectangular billet has been produced. The compound rolling behavior of Ti–50Al billet has been studied using this equipment. In order to study the deformation distribution of compound rolling, the flow net method for strain measurement has been employed. The deformation differences between compound rolling and flat rolling have been investigated with the commercial finite element method (FEM) code DEFORM-3D. The microstructure and the hardness from the surface to the center of the Ti–50Al billet developed through compound rolling has been characterized. These results indicate that the compound rolling technique results in severe plastic deformation near the surface with limited strain towards the center of the billet. This can result in compound microstructures, with fine recrystallized grains in the near surface region and the original directionally solidified microstructures in the center, and improve the hardness on the surface of the billet significantly.

Tolerance Design of Logarithmic Roller Profiles in Cylindrical Roller Bearings

A logarithmic profile is essentially optimal crowning geometry for rolling machine elements such as bearing rollers and raceways. Although some design methods of the profile have been proposed, they do not refer to the tolerance of the geometry required in engineering applications and in production. This paper shows how to define the tolerance range associated with the optimum roller profile, previously suggested by one of the authors. The overall tolerance is reasonably defined by giving the reduced amount of roller radius at three points so that the von Mises equivalent stress will not exceed a specified limit, where the point locations are not measured from the roller end but from the intersection of the crowning and the chamfer. For the purpose of design usefulness, the tolerance expression is offered in dimensionless form.

Thermal Deformation Analysis of the Rotating Roller in Planar Flow Casting Process

In planar flow casting (PFC) process for the manufacture of amorphous ribbon, the thermal deformation of the rotating roller is an important phenomenon that is not only for accuracy controlling the proper nozzle/substrate gap size to obtain the desired ribbon with uniform thickness and excellent quality, but also for stabilizing the manufacture and minimizing its cost. In this paper, by mapping and interpolating 2D temperature results (which are obtained by a conjugated solution of the thermal-fluid dynamics of the melt puddle zone and the heat transfer of rotating roller zone) into a 3D temperature distribution of the roller, the thermal behavior and the roller deformation features of rotating roller at a quasi-steady state and over a initial transient evolution in PFC process are analyzed. The effect of operating parameters and PFC configurations on the thermal and deformation behavior is theoretically examined. Results show that in PCF process, the plastic deformation of the roller occurs in a very thin surface layer under melt puddle, sharply decaying a lower value along the circumferential revolution. The thermal expansion is non-homogeneous on the roller surface and the location of the maximum roller expansion is beyond the coverage of the melt puddle due to the roller revolution. There is a rapid increase of the thermal expansion from the melt contact to ribbon separation. However, for the small melt puddle length, the fluctuation of the expansion along circumferential direction is very small (<10 μm) while the variation of the expansion along ribbon width direction is larger. With the evolution of the time, the thermal expansion rapidly increases at the beginning of the casting process and gradually increases, and the fluctuation of the roller surface expansion increases until a quasi-steady state when the heat balance is reached. The operating parameters and PFC configurations affect the magnitude and profile of roller thermal expansion. It is necessary to pay great attention to the effect of large roller deformation on the small nozzle/roller gap and thin ribbon thickness to avoid some qualities and operating problems in PFC process for the formation of amorphous ribbon.

An Optimum Design of Crowned Cylindrical Roller Bearings Using Genetic Algorithms

The long fatigue life is the one of the most important criterion for the design of rolling bearings, however, due to complex and diverse internal geometries, each type of rolling bearings require a different design formulation. To increase the life of cylindrical roller bearings, the profile (or the crowning) of the roller plays an important role. A flat profile of the rolling element results in the edge stress concentrations at roller ends. A circular crowning of roller eliminates the edge stress concentration at the lower and moderate loads only; however, it develops edge stress concentrations at heavy loads. The logarithmic profile of the roller results in no edge stress concentration at the low, medium, and heavy loads; distribution of contact stresses is also nearly uniform along the length of the roller. A design methodology for the optimum design of cylindrical roller bearings with the logarithmic profile has been outlined. A nonlinear constrained optimization problem has been formulated for the design of cylindrical roller bearings with logarithmic profiles and is optimized by using real-coded genetic algorithms. The change in roller profile has not been accounted for explicitly in the standard definition of the dynamic capacity; hence, for the present case directly the Lundberg–Palmgren life equation has been chosen as an objective function. Design variables include four bearing geometrical parameters and the two logarithmic profile generating parameters are considered. In addition to these, another five design constraint constants are also included, which indirectly affect the fatigue life of cylindrical roller bearings. The five design constraint constants have been given bounds based on the parametric studies through initial optimization runs. The effective length of the roller is taken corresponding to the standard roller diameter, which has standard discrete dimensions. Constraint violation study has been performed to have an assessment of the effectiveness of each of the constraints. A convergence study has been carried out to ensure the global optimum point in the design. A sensitivity analysis of various geometric design parameters has been performed using the Monte Carlo simulation technique, in order to see changes in the fatigue life of the bearing. Illustrations show that the multiplier of the logarithmic profile deviation parameter has more effect on the fatigue life as compared with other geometric parameters.

円筒ころ軸受における対数クラウニングの公差設計

A logarithmic profile is essentially optimal crowning geometry for rolling machine elements such as bearing rollers and raceways. Although some design methods of the profile have been proposed, they do not refer to the tolerance of the geometry required in engineering applications and in production. This paper shows how to define the tolerance range associated with the optimum roller profile, previously suggested by one of the authors. The overall tolerance is reasonably defined by giving the reduced amount of roller radius at three points so that the von Mises equivalent stress will not exceed a specified limit, where the point locations are not measured from the roller end but from the intersection of the crowning and the chamfer. For the purpose of design usefulness, the tolerance expression is offered in dimensionless form.

Experimental Comparison Between Partially Crowned and Logarithmic Roller Profiles in Cylindrical Roller Bearings

A logarithmic profile is an essentially optimal geometry for rolling machine elements such as bearing rollers and raceways. Under most conditions of loading, it yields less stresses to give longer endurance. Lundberg first suggested the basic profile, and some researchers followed him by modifying it to suit engineering requirements. The authors also proposed a mathematical optimization method for various profiles including a logarithmic one in roller bearing applications. In this paper, rolling contact fatigue life tests are carried out to make a comparison of logarithmic, standard partially crowned and modified partially crowned rollers when they are applied to cylindrical roller bearings. Results show that the logarithmic and modified partially crowned rollers are comparable in fatigue life, and outlast the standard partially crowed rollers if they are fully lubricated. On the other hand, under poor lubrication, the logarithmic rollers are found to yield outstanding fatigue life over the modified partially crowned ones.

Online dressing of profile grinding wheels

Improving the dressing accuracy and efficiency of profile grinding wheels has been increasingly demanded. The significance is addressed in the practical application of precision engineering. In this study, an online dressing system of profile grinding wheels is introduced. A special feature of the system is the application of the non-contact image measuring method used to evaluate deviation of the grinding wheel’s edge in determining the timing and amount of dressing. Diamond form rollers were selected to generate the profile grinding wheels with steep profile flanks by taking advantage of their high flexibility, short dressing times, and low wear rate. A series of grinding and dressing tests were carried out to investigate the dressing accuracy and surface quality for the profile grinding wheels with the proposed system. Through repeated experimental investigations, it was found that the dressing force is a key parameter in determining the number of passes needed in achieving high efficiency dressing. This is to assure that the length of the dressing time, and waste of the dresser and grinding wheel can be minimized. Other main dressing conditions that influence the grinding wheel and workpiece roughness include speed ratio, cross feed and roller profile radius.

Cage Instabilities in Cylindrical Roller Bearings

A six-degree-of-freedom model was developed and used to simulate the motion of all elements in a cylindrical roller bearing. Cage instability has been studied as a function of the roller-race and roller-cage pocket clearances for light-load and high-speed conditions. The effects of variation in inner race speed, misalignment, cage asymmetry, and varying size of one of the rollers have been investigated. In addition, three different roller profiles have been used to study their impact on cage dynamics. The results indicate that the cage exhibits stable motion for small values of roller-race and roller-cage pocket clearances. A rise in instability leads to discrete cage-race collisions with high force magnitudes. Race misalignment leads to a rise in instability for small roller-cage pocket clearances since skew control is provided by the sides of the cage pocket. One roller of larger size than the others causes inner race whirl and leads to stable cage motion for small roller-race clearances without any variation in roller-cage pocket clearance. Cage asymmetry and different roller profiles have a negligible impact on cage motion.

A study on seamless tube in the planetary rolling process

In this paper, the finite element method and the dual-stream functions upper bound method are selected to analyze the tube rolling process with a planetary rolling mill. Three-dimensional elastic–plastic finite element simulations with special emphasis on the determination of the roller profile and realistic contact conditions between the rollers, workpiece and mandrel are used to reveal the deformation characteristics of seamless tube during the rolling process. In addition, the kinematically admissible velocity field of the deforming tube is described in terms of two stream functions so that the velocity components of the deforming tube can be obtained through the upper bound analysis. In both analysis methods, the equation of meshing is used to determine the contact condition between the rollers and the workpiece. The results from both methods with different variables are observed and compared.

Effect Of Roller Profile On Cylindrical Roller Bearing Life Prediction—Part II Comparison of Roller Profiles

Four roller profiles used in cylindrical roller bearing design and manufacture were analyzed using both a closed form solution and finite element analysis (FEA) for stress and life. The analyzed roller profiles were flat, end tapered, aerospace, and fully crowned and loaded against a flat raceway. Four rolling-element bearing life models were chosen for this analysis: those of Weibull; Lundberg and Palmgren; Ioannides and Harris; and Zaretsky. The flat roller profile without edge loading has the longest predicted life. However, edge loading can reduce life by as much as 98 percent. The end-tapered profile produced the highest lives, but not significantly higher than those produced by the aerospace profile. The fully crowned profile produced the lowest lives. Except for the flat roller profile, the predicted lives with the FEA method exceed those with the closed form solution. The fatigue limit proposed by Ioannides and Harris equates to one-half the value of a compressive residual stress that may exist in a rolling bearing steel. Presented at the 55th Annual Meeting Nashville, Tennessee May 7–11, 2001

Profile determination of a tube-straightening roller by envelope theory

A simple method by applying envelope theory to determine the profile of a tube-straightening roller has been studied. The roller profile is defined as the envelope of a three-parameter family of spatial curves. The three parameters are rotation, translation and rotation, which generate by their motions the spatial curves. The envelope theory is utilized by an implicit function. To avoid undercutting of the surface of the straightening roller, principal curvatures and contact lines are analyzed. It is found that a spherical-end cutter is needed in making the roller. The radius of the spherical-end cutter is similar to that of the radius of the tube. Due to available mathematical software, the complete contour of the tube-straightening roller can be simulated using a personal computer, as shown in this paper.

Parameter Identification and Experimental Investigations of Unconventional Railway Wheelset Designs on a Scaled Roller Rig

SUMMARY In this paper a parameter identification method for multibody systems is applied to a 1:5-scaled two-axled railway vehicle with conical wheels on a roller rig with UIC 60 roller profiles. The aim is to demonstrate how parameter identification in connection with constrained multibody systems and dynamical measurements can be performed The process of mathematical modelling and solution approach is described, where emphasis is laid on the structure of equations, modelling of the wheel-roller contact, numerical methods and the representation of the parameter identification method for the determination of the unknown stiffness and damping parameters as well as uncertain parameters like the coefficient of friction and manufacturing imperfections of the vehicle Additionally it is indicated that the 1:s-scaled railway vehicle can be utilized for running behaviour experiments with unconventional wheelset designs.

Shear spinning technology for manufacture of long thin wall tubes of small bore

Metal spinning is a process in which the deformation stresses are localized to a small region. The material is made to flow and move over the rotating mandrel with the help of a spinning tool mounted on a saddle and moving along the profile of the mandrel. The process has been in use for a long time to produce axi-symmetric shapes and tubular products with small L/D ratio. However, the conventional process fails to produce long, thin-wall, small-bore tubes. The process has been modified to spin long, small-bore, thin-tubes in hard-to-work materials such as CP titanium, Incoloy 825, Inconel 600 and Stainless steel AISI-304. The technology of making tubes in the above materials has been developed. The effect of feed, roller profile, percentage reduction and lubricants used on the surface finish and the power consumption when working with AISI-304 is reported. It is observed that the mechanical properties of the product improve considerably, close dimensional tolerances are obtained on outside and inside diameters and the wall thickness, and high reductions are possible without intermediate annealing. The new process is economically viable for producing tubes in high-strength materials, particularly when the volume of production is not high. The special features of the modified machine are given also.