Hollow Roller Research Articles

Study of CNC skew rolling of hollow rail axles with a mandrel

The manuscript presents a new manufacturing technology for the production of hollow railway axle forgings. The manufacturing technology analyzed is based on three-roll skew rolling (TRSR) using a computer numerically controlled (CNC) rolling mill. The study focused on comparing the rolling capability of hollow products without and with a mandrel calibrating the hole of the forging. The influence of tube billet size on the rolling process was also analyzed. FE analysis and experimental studies were carried out. An analysis of the accuracy of the internal hole of the forging depending on the adopted parameters of the rolling process was carried out. Based on numerical simulations, the state of strain and the flow pattern of the material and temperature distribution during rolling were determined. The force parameters of the rolling process of hollow forgings were also analyzed. Based on the research, a two-stage rolling technology for rolling hollow railway axle forgings was proposed. The results obtained indicate the suitability of using a calibrating mandrel to improve hole accuracy in hollow forgings rolled from a tubular billet. The gap c between the bore diameter of the forging and the diameter of the mandrel was measured. Increasing the tubular billet dimensions from Ø42.4 × 10 mm to Ø48.3 × 12.5 mm reduced the gap c by 49.8%. Rolling the billet Ø51 × 14.2 mm in two passes compared to rolling in one pass reduced the gap c by 45.5%.

Finite Element Analysis of Solid and Hollow Roller Bearings to Predict the Influence of Contact Factors on Cage Slip

This study examines the influence of contact factors such as bearing deformation, contact width and contact pressure on cage slide in cylindrical roller bearings. A cylindrical shaped roller bearing test setup is designed in order to determine the operating speed of bearing components under varying working circumstances. Solid and hollow roller bearings are analyzed using finite element technique, and the contact parameters are obtained. The cage slip obtained by experimental work is correlated with the contact parameters of hollow and solid shaped roller bearings. The specific load acting on solid rollers at various angular positions and the corresponding bearing deflection are obtained by FEA and the bearing run out is estimated. A new methodology is developed for deriving the contact mechanics of hollow roller to predict contact pressure and contact width from the roller deflection. The effect of hollowness on these parameters is derived and the corresponding cage slip is correlated. The effect of hollowness on bending and resultant stresses is obtained by numerical and analytical methods to correlate the stability of hollow roller bearing with the percentage of hollowness.

Experimental and Theoretical Study on Forming Film Properties of Hollow Cylindrical Rollers

Bending deformation of a hollow cylindrical roller (HCR) was calculated by curve bending theory and slice technology. Furthermore, an elastohydrodynamic lubrication (EHL) model involving hollow rollers was established by coupling the finite line EHL model and bending deformation. Measurements of film thickness for hollow rollers were carried out by using a line-contact optical EHL test rig, and the experimental data and theoretical results agreed well with each other. For a roller with a straight-line profile, the hollow structure could reduce pressure peak at the roller ends, but the edge effect was still present. The film thickness at the ends unfortunately could not be improved by such hollow structures, unless a profile modification for the operating surface is designed.

Classification of Hollow Rollers of Roller Machines for the Treatment of Polymeric Materials and Rubber Compounds (Survey of Patents)

Classification of Hollow Rollers of Roller Machines for the Treatment of Polymeric Materials and Rubber Compounds (Survey of Patents)

Dynamic investigation and alleviative measures for the skidding phenomenon of lubricated rolling bearing under light load

The skidding phenomenon occurs during the operation of rolling bearing under the light load owing to the design error, which will intensify the surface damage and lead to noise and abnormal vibration. In this study, a skidding dynamics model of lubricated rolling bearing is established considering the interactions between the roller and races, as well as the cage. The effect of lubricant on the dynamic characteristics of the rolling bearing is characterized as the lubricating oil stiffness, central film thickness, time-varying friction coefficient between the roller and race, passing flow resistances of rollers, and resistance torques. In addition, the nonlinear contact and structure deformations of rollers are formulated. For mitigating the skidding phenomenon of the roller under light load, the effect of roller number, inside radius of the hollow roller, density and viscosity of the lubricant, interference fit, and radial load are analyzed. The results indicate that the skidding phenomenon of the roller is induced by the lesser tangential roller-race friction forces and larger passing flow resistances of rollers. It is helpful to intensify the interactions at the roller-race interface or/and decrease the running resistance by reducing the roller number, decreasing the lubricant density, or choosing the correct viscosity of the lubricant. Besides, the effect of interference fit and increasing radial load is significant on the premise of not changing the design parameters of the rolling bearing.

Relative contact width evaluation of end hemispherical cavities rollers as an indication of Hertzian contact pressure

In a recent investigation, the end hemispherical cavities (EHC) rollers exhibited better strength against fracture than hollow rollers. Furthermore, EHC rollers looked promising from a higher fatigue life aspect than conventional solid rollers in a simulation study. Therefore, it necessitated further exploration of the EHC roller concept and to this end, in the present investigation, the contact widths of EHC rollers were relatively evaluated to judge its contact stresses' behavior with respect to the solid roller because the contact stresses are responsible for the fatigue life of rolling bearings. In the experiments, the contact footprints were obtained by forcing specimens of rollers against chemically etched surfaces and were examined by a microscope for measurement of contact widths. The experimental trials were performed with individual roller-on-plate tests and also with full-bearing samples. The etch correction factor was used to correct anomalies of real and observed contact widths due to etching film thickness. The parabolic relationships were established for roller variants which yielded constants signifying their relative ranks. The contact semi-widths, thus derived from corrected experimental results of individual roller-on-plate tests, demonstrated good agreement (<5%) with those derived from simulation results. The results of full-bearing sample tests for roller variants also ranked same as individual roller-on-plate tests. The encouraging results of contact semi-width assuredly favor the prospects of relatively higher fatigue life in case of EHC rollers.

Dynamics of exit section of automatic mill of pipe rolling line

Nonuniformity of pipe wall thickness is one of significant indices, determining quality of hot-rolled seamless pipes. One of the reasons of increased nonuniformity arising is dynamics of exit section mechanisms of pipe rolling line (PRL). Results of study of mandrel holding mechanism dynamics of PRL presented. Dynamic models of exit section, accounting parameters of technological process and inertia of a rolled hollow billet elaborated, which enabled to determine the character of dynamic processes at the exit section of PRL automatic mill. Differential equations of exit section elements motion at the exit section of PRL automatic mill were made up. The solution of the differential equations system was obtained in a numerical form by application of Runge‒Kutta method for correspondent dynamic models of exit section based on the example of calculations for ТПА-350 automatic mill. The pattern of dynamic processes arising at the exit section was specified at realization of the whole technological process of a hollow billet rolling at automatic mill, taking into consideration alternative action from the side of deformation center and mass of the rolled hollow billet. It was shown, that the specified solution of the task for three advanced dynamic models of mechanical system considerably differs from those of the known mathematical models. It was established, that the dynamics of the mandrel holding mechanism of ТПА-350 automatic mill equivalently form the mechanism of finished pipes geometry forming. Analysis of dynamic models of the mill exit section enabled to select the necessary technological and dynamic parameters of the mechanical system, to determine stable modes of hollow billets rolling at the ТПА-350 automatic mill. Results of the study of dynamics of exit section ТПА-350 automatic mill presented. A scheme of modernization of the exit section ТПА-350 automatic mill proposed, which enables to realize rational modes of operation accounting level of mechanical system dynamics and to control quality (geometric parameters) of the rolled pipes.

Study of the process of formation of tubes end sections during longitudinal rolling in grooves formed by a different number of rolls

The work substantiates the relevance and highlights the degree of development of the research topic. The main advantages and disadvantages of the process of rolling hollow billets with the use of modern longitudinal rolling mills with 2 and 3 roll grooves are noted. With the help of physical and computer modeling, a study of the process of longitudinal rolling of pipes using 2 and 3 roll passes was carried out, for the formation of end sections (scrap). Established and numerically reflected the relationship between the size of the reduction of passes of a continuous rolling mill with 3-roll and 2-roll stands and the length of the end sections of the pipes. It is clear that the use of 3 rolls, forming a groove, allows to reduce the total end cut by 1.5 times, in contrast to 2 rolls. It has been determined that the main technological factors influencing the formation of the end sections are the ratio of the external diameter to the wall thickness of the strip (D/S), the reduction along the wall thickness, the elongation ratio, and the number of rolls required to form the groove. An empirical formula has been obtained for calculating the length of the end trim, which makes it possible to evaluate the influence of the number of rolls in the stand, the D/S ratio and the stretch ratio.

Contact Mechanics Response of Composite Cylindrical Roller Bearings Based on FEM

In response to the increasing demand for the working performance of cylindrical rollers in the industry, in this paper, PTFE and hollow cylindrical roller bearings are combined and improved to form composite cylindrical roller bearings. Establish a numerical calculation model of composite cylindrical roller bearings, which compares with hollow cylindrical rollers, and analyze the influence of filling degree and magnitude of load on various parameters of composite cylindrical rollers. The result shows that the mechanical properties of composite cylindrical roller bearings are better than hollow cylindrical rollers. It can significantly improve the bending stress of the inner wall of the roller; the greater the filling degree, the less obvious the stress concentration phenomenon at the two ends of the roller contacting the bus bar, and the higher the equivalent stress value on the inner wall of the roller. The optimal filling degree is affected by the load, and the optimal filling degree is different under different load conditions. The greater the working load, the more obvious the stress concentration at both ends of the composite cylindrical roller.

Strength Against Fracture of End Hemispherical Cavity Roller Under Static Loading: Experimental and Simulation Investigation

Abstract Enhancement in fatigue life of the rolling-element bearing has been captivating since years. The hollow concept had been triggered years back; however, it could not catch widespread applications due to catastrophic failure. Thus, any novel concept of the rolling element must be assessed for its strength against catastrophic failure before competing for better fatigue life on field with other alternatives. This paper commences with the outcomes of the comparative assessment of the experimental evaluation of strength against fracture under static loads for layered and hollow rollers with solid rollers, which devise the requirements for new concepts. The end hemispherical cavity (EHC) roller concept, being a proper geometrical blending of solidity and hollowness, prospects to overcome the strength concern along with a considerable reduction in contact stresses. Thus, experimental investigation was conducted with full-bearing fracture tests and individual roller specimens fracture tests for five variants: EHC, solid, layered, 61H, and 37H (hollow rollers with 61% and 37% hollowness, respectively). The simulations were carried out to support the outcomes of experimental trials. The experimental results with full-bearing samples and individual roller specimens demonstrated ranking as follows: EHC, 37H, layered, and 61H. The EHC roller concept was substantiated to be stronger than hollow and layered rollers besides prompting appreciable reduction in contact stresses compared with the solid roller. The simulation results agreed well with experimental results of fracture tests, and the recommendations from findings of failure theories (maximum normal stress, distortion energy, and maximum shear stress) adopted for estimating fracture load for rollers have been discussed.

Study of the dynamics of ТПА 350 automatic mill working stand elements

To form a necessary geometry of a hollow billet to be rolled at a pipe rolling line, stable dynamics of the base equipment of the automatic mill working stand has a practical meaning. Among the forces, acting on its parts and elements, significant by value short-time dynamic loads are the least studied phenomena. These dynamic loads arise during transient interaction of the hollow billet, rollers, mandrel and other mill parts at the forced grip of the hollow billet. Basing of the calculation scheme and dynamic model of the mechanical system of the ТПА 350 automatic mill working stand was accomplished. A mathematical model of dynamics of the system “hollow billet (pipe) – working stand” within accepted calculation scheme and dynamic model of the mechanical system elaborated. Influence of technological load of the rolled hollow billet variation in time was accounted, as well as variation of the mechanical system mass, and rigidity of the ТПА 350 automatic mill working stand. Differential equations of oscillation movement for four-mass model of forked sub-systems of the automatic mill working stand were made up, results of their digital calculation quoted. Dynamic displacement of the stand elements in the inter-roller gap obtained, which enabled to estimate the results of amplitude and frequency characteristics of the branches of the mill rollers setting. It was defined by calculation, that the maximum amplitude of the forced oscillations of elements of the ТПА 350 automatic mill working stand within the inter-roller gap does not exceed 2 mm. It is much higher than the accepted value of adjusting parameters of the deformation center of the ТПА 350 automatic mill. A scheme of comprehensive modernization of the rollers setting in the ТПА 350 automatic mill working stand was proposed. It was shown, that increase of rigidity of rollers setting in the ТПА 350 automatic mill working stand enables to stabilize the amplitude of forced oscillations of the working stand elements within the inter-rollers gap and considerably decrease the induced nonuniform hollow billet wall thickness and increase quality of the rolled pipes at ТПА 350.

Development of a novel low-temperature differential hollow roller using an ultra-thin heating element of graphene polymeric composite material

In this study, an easy and low-temperature differential hollow roller using an ultra-thin heating element of graphene polymeric composite material by wire bar coating technique was first demonstrated and fabricated successfully. In contrast to the conventional hot roller, this study confirmed the flexibility of high uniform temperature distribution in the rolling system. The dynamic-state temperature differential of four quarter positions and horizontal positions can be controlled within 2.8 °C and 1.2 °C with a voltage of 40 V, respectively. High-Temperature stability of long-term steady-state temperature was confirmed and the voltage only needs 25 V to get a steady-state temperature of almost 160 °C.

Experimental investigation of an elastic contact between a layered cylindrical hollow roller and flat plate

A novel roller design, a layered cylindrical hollow roller is suggested for roller type bearings, in which a small hollow cylinder is embedded into another large hollow cylinder with the same percentage of hollowness. This paper deals with a theoretical and experimental investigation for the cylinder-on-flat type contact interaction. In theoretical calculation Hertz theory is used for half contact width calculation. While experimental analysis is carried out with the help of “footprint method” for analyzing a real contact area between elastic solids. In footprint method the indentation of the roller on flat plate with regard to the applied load is measured. The theoretical data is compared for the validation of experimental technique. The test results are very close and similar with the theoretical data. With the help of this experimental technique, contact analysis between hollow roller and flat plate and between layered cylindrical hollow roller and flat plate have been carried out. Finally, in this work, experimentally evaluated contact width values are compared between hollow roller and layered cylindrical hollow roller. The experimental results suggested that the layered cylindrical hollow roller has larger contact width as compared to hollow roller with the same outside dimension and hollowness under same compressive loading conditions.

The optimisation of the cylinder-spiral soil-cultivating roller

Designed cylinder-tillage spiral skating rink with spiral work items, which form a fine lumpy structure of the sowing layer of soil with grain size corresponding to agrotechnical requirements, while helping the soil surface, mulching the top layer of soil over the seeds, seal the depth of their placement, providing the required contact of seeds with soil is necessary to ensure the uniformity of germination. At the theoretical level, it is determined that an increase in the pinching angle leads to an increase in the size of the hollow smooth pipe of the roller. This occurs while increasing the depth of deformation of the layer of crushed soil and the radius of the clump of soil. However, a change in the radius of a hollow smooth roller of more than 0.3 m does not lead to a slight increase in the pinching angle. Therefore, increasing the radius of the hollow smooth roller over 0.3 m is not rational, as it will increase the metal content of the structure. After analyzing the obtained mathematical models of the soil treatment process with a roller, we optimized the parameters of a cylindrical-spiral roller: speed of 11 km/h, mass of ballasting loads of 100 kg, step of the spiral turn of 40 mm, and the departure of the spiral screw of 35 mm. These modes ensure the formation of a qualitatively compacted soil layer in the zone of planting seeds of agricultural crops, which is confirmed by the maximum value of the processing quality criterion for matching the density of the soil after rolling with a cylindrical-spiral roller CCS = 0.98 (while the density of the sown layer addition 1185...1215 kg/m3), which fully satisfies the agrotechnical optimum. The yield of barley of the Nutans-553 variety became higher after the use of an innovative cylindrical-spiral roller by 6.4 % and 9.3 %, respectively, of the yield after the impact of serial ККSh rollers and ring rollers of the seeding machine. In the course of evaluating the metal consumption of structures of the innovative cylindrical-spiral roller and the ring-spur roller, a difference of 70% per unit width of the grip was revealed.

Investigation on the hole evolution and forming dimensions during cross wedge rolling hollow shaft with mandrel

The cross wedge rolling (CWR) is an efficient and green process for manufacturing hollow shafts. The mandrel plays an important role in controlling hole shape during the process of CWR hollow shafts with mandrel. To obtain precise dimensions of rolled parts, the hole evolution during rolling in different parameters is need to be investigated further. This paper deeply studied the effect mechanism of mandrel on hole of hollow shaft. A finite element model (FEM) was developed to analyse the evolution process of inner hole during CWR hollow shaft, and the results shown that the wall of hollow shaft is rolled and the hole dimensions is grow after inner hole contacts mandrel. The hole evolution process can be considered as the rolling of wall under the effect of CWR dies and mandrel. A layer gap between the mandrel and the hole of rolled parts, defined as diameter difference, is caused because of the hole expansion. The effect of process parameters on the diameter difference was investigated by conducting CWR experiments. It shown that the diameter difference increases with stretching angle and mandrel diameter; and decreases with forming angle, compression ratio and wall thickness. The results reveals the hole evolution and the causes of the diameter difference during CWR hollow shafts with mandrel, and can provide theoretical guidance for the production application.

Step and scanning lithography for patterning seamless microstructures on the inner surface of a hollow roller

This paper presents a step-and-repeat photolithography method for patterning seamless microstructures on the inner cylindrical surface of a hollow roller. The purpose is for subsequent replication of the microstructures onto the surface of another mold for roller imprinting. The processes include coating of a photoresist (PR) layer, ultraviolet (UV) exposing the PR layer with a photomask, and finally PR developing to obtain patterned microstructures on the inner cylindrical surface. To achieve seamless patterning, UV exposure process is first conducted locally on a narrow and slender area and then consecutively repeated. Through efforts on precision mechanical system design and using a collimated UV light source, consecutively exposed areas can be seamlessly stitched together to form a complete UV exposed pattern on the inner cylindrical surface. Experiments have been carried out using three photomasks with hexagonal arrays of hexagons and circles. Typical feature sizes are around ten to a few tens of micrometers. Details on the experimental results as well as future perspectives on the applications of this new type of lithography for roller imprinting will be addressed.

Numerical and experimental research on cross wedge rolling hollow shafts with a variable inner diameter

The precise forming of inner hole has been a major technical difficulty in the cross wedge rolling (CWR) of hollow shaft. This paper proposes a new process to form hollow shafts with variable inner diameters by using the CWR with mandrel control. The forming characteristics and dimension precision of this process are analyzed by combining finite element modelling (FEM) and forming trials. The hole step of hollow shaft with variable inner diameter is formed in a spiral pattern. The helixes result in many micro-steps in hole step when forming the right-angle inner step. The metal flow lines demonstrated that mandrel step hindered the axial metal flow of inner hole and the metals were accumulated in hole step. The rolling load increases in the process of forming hole step. The mandrel is subjected to axial load when hole contacts the mandrel step. The roundness can be improved by reducing the mandrel diameter in knifing position. The axial accuracy of inner diameter can be classed as three parts: hole expansion, stable rolling, hole shrinkage. The compensated mandrel was designed to improve axial precision of inner diameter. The results showed that the inner hole dimension can be effectively controlled.

Алгоритм расчета энергосиловых параметров процесса раскатки гильзы в непрерывном стане

Алгоритм расчета энергосиловых параметров процесса раскатки гильзы в непрерывном стане

Analysis of Machine Maintenance Processes by using FMEA Method in the Sugar Industry

Sugar is the daily basic need of human life. It is made from cane trees and manufactured using a milling machine in the early stages. This machine is operated 24 hours per day; consequently, it should be in a good condition and the company must be able to ensure the machine can run well by scheduling regular maintenance. This study aimed to investigate the potential failure of manufacturing process to provide some recommendations for improvement. Failure Mode and Effect Analysis (FMEA) method was applied to analyze the situation, and Logic Tree Analysis (LTA) was implemented to classify the types of improvement. This study found 13 failure modes, including a loose hammer tip, a broken end of the cutter, a non-balanced hammer rotation, a broken hammer handlebar, a broken wheel bearing, a loose switch, a loose split pen, a loose fastener bolt, an overload, a destroyed rubber seal, a broken turbine coupling, a broken screw-bolt, and a hollow roller. Meanwhile, the classification of improvement consisted of 3 categories namely safety problem (A), outage problem (B), and economic problem (C). Subsequently, the A category recommended setting up the machine in accordance with SOP while the B category recommended inspecting the machine routinely and preparing parts. In addition, the C category recommended performing accurate installation, lubrication, and cleaning.

Mechanism and force-energy parameters of a hollow shaft’s multi-wedge synchrostep cross-wedge rolling

First, the rotation condition of a hollow shaft’s multi-wedge synchrostep cross-wedge rolling (MSCWR) is determined and the relevant influencing rule is illustrated based on a mechanical model of the hollow shaft and the theory of solid shaft’s rotation condition. The influence rule states that the increasing number of wedges increases the shrinkage rate of the hollow shaft and diminishes the rotation conditions, which can be improved by increasing μ on the forming surface of the hollow rolling mold, setting the stretching β, and forming α angles at approximately 4°–12° and 15°–35°, respectively. Second, a rigid-plastic finite element model is established for the hollow shaft with MSCWR by using the DEFORM-3D software, and the deformation mechanism of the hollow shaft is illustrated. The deformation degree of the rolling piece at the stretching stage decreases gradually from the surface to the interior of the hollow shaft, and radial compressive and transverse tensile strains interact with each other, thus resulting in an elliptic cross section of the hollow shaft. Stress field is mainly distributed in the exterior margin and then permeates into the inner part along the direction of the wall thickness, gradually transforming from compressive stress into tensile stress. Third, the influence of mechanical parameters on hollow shaft rolling is analyzed. The increased stretching angle increases the radial force, transverse force, and rolling torque and decreases the axial force. Moreover, the enlarged forming angle reduces the radial and transverse forces, while the decreased rolling torque increases the axial force. Finally, the 1:5 MSCWR experiment on the hollow shaft verifies the proposed finite element model’s accuracy. Results of the research provide a theoretical basis for the MSCWR of a precise hollow shaft.