Rail Grinding Research Articles

Development of rail technology for high speed railway in China

PurposeThe purpose of this paper is to summarize the status and characteristics of rail technology of high-speed railway in China, and point out the development direction of rail technology of high-speed railway.Design/methodology/approachThis study reviews the evolution of high-speed rail standards in China, comparing their chemical composition, mechanical attributes and geometric specifications with EN standards. It delves into the status of rail production technology, shifts in key performance indicators and the quality characteristics of rails. The analysis further examines the interplay between wheels and rails, the implementation of grinding technology and the techniques for inspecting rail service conditions. It encapsulates the salient features of rail operation and maintenance within the high-speed railway ecosystem. The paper concludes with an insightful prognosis of high-speed railway technology development in China.FindingsThe rail standards of high-speed railway in China are scientific and advanced, highly operational and in line with international standards. The quality and performance of rail in China have reached the world’s advanced level. The 60N profile guarantees the operation quality of wheel–rail interaction effectively. The rail grinding technology system scientifically guarantees the long-term good service performance of the rail. The rail service state detection technology is scientific and efficient. The rail technology will take “more intelligent” and “higher speed” as the development direction to meet the future needs of high-speed railway in China.Originality/valueThe development direction of rail technology for high-speed railway in China is defined, which will promote the continuous innovation and breakthrough of rail technology.

Optimisation design of grinding rail profile of metro lines for small radius curved track based on the GFC method: a case study

The rail side wear in small radius curved track of metro lines is a serious problem in railway maintenance, which reduces the curve passing performance and shortens the service life of the wheel and rail. To improve the vehicle's curve passing performance and reduce rail wear, a localized grinding profile design method for sharp curves was developed. The GFC profile generation method was used to generate the profiles for the curved track of the metro line. Then a metro vehicle-track dynamic model was established to calculate the wheel rail contact parameters, objectives and constraints. The profiles are optimized by the KSM-PSO optimization algorithm. Finally, a simulation analysis of the curve passing performance and wheel-rail wear of the optimized profile was carried out. When the metro vehicle passes through the curved track with a curve radius of 450m, the optimized rail profile can effectively reduce the wear of the rail, the wear of the high rail in the curved track is reduced by 20.18%. The localized rail grinding of the curved track can effectively reduce the rail side wear, the GQI index is also significantly improved. This study can guide the design of rail grinding profiles for the metro lines.

Optimisation of rail profile and grinding pattern in the curve section of a subway

During routine rail maintenance, rail grinding of sharp curves is challenging. In particular, setting up the grinding pattern is essential. A rail-grinding pattern optimisation method is proposed based on the mathematical relationship between the grinding pattern parameters and geometric parameters of the rail grinding profile. In this method, the design variables and constraints are reasonably selected, and a multi-objective optimisation function considering the wheel-rail contact stress, wheel-rail lateral force, and rail grinding amount is established. The optimisation model is solved using a chaotic microvariation adaptive genetic algorithm. The optimisation method is applied to the repairable grinding of a worn rail in a metro curve section. The results demonstrate that using this method can realise an ideal grinding pattern with the expected grinding effect in addition to high accuracy and high optimisation speed. The wheel-rail contact characteristics, wear characteristics, and train dynamic performance are significantly improved after rail grinding; this is significant for conducting grinding operations and improving the train’s curve-passing ability. Therefore, this study provides theoretical guidance for formulating rail-grinding patterns.

Acoustic roughness outcomes from rail maintenance processes

Rail roughness is a key determinant of the rolling noise emissions of many railway systems, particularly those systems where wheel roughness is relatively low. Rail roughness can vary considerably. The noise emissions from trains operating on very smooth, quiet, worn in systems can be 25 dBA less than the noise from identical trains operating on the same trackform but with rough or corrugated rails. Rail roughness varies over time, with changes resulting from gradual wear during normal operations but also from maintenance interventions. Rail grinding, milling or acoustic polishing can cause immediate and sometimes dramatic changes in rail acoustic surface condition, and noticeable changes in noise character. This paper documents the acoustic roughness outcomes achieved by various rail maintenance processes, in comparison to acoustic roughness from worn in tracks. The data presented includes measurements of surface finish from conventional rail grinding, rail milling, and from newer specialist acoustic grinding technologies. The rail roughness results are used to demonstrate the differences in noise emissions following rail maintenance activities. The results confirm the importance of maintaining low rail roughness as a means of noise control at source.

Экспериментальные исследования режимов скоростного шлифования рельсов

Introduction. Rails’ grinding in the conditions of a railway track is a priority for extending its life cycle due to the timely removal of tread surface defects and formation of required transverse profile. Today, 14 RSHP-48 rail grinding trains are used in Russia. At the same time, most rail grinding trains are ending its service life. Therefore, the development of a fundamentally new rail grinding train with increased efficiency is an urgent task. Siberian transport university is working together with the Kaluga plant “Remputmash” to create a new rail grinding train named RSHP 2.0. The rail grinding train RSHP 2.0 is based on the technology of high-speed rail grinding, which is based on increasing working speed of rail grinding train by increasing rotational speed of grinding wheels and setting the angle of attack. The aim of this work is to study rails’ grinding modes on a specially designed installation URSH, which implements the technology of high-speed grinding rails by increasing speed of grinding wheels rotation up to 5,000 rpm. Research methods. Grinding wheel speed control was carried out by IT-5-ChM “Termit” electronic tachometer and “Megeon 18005” laser tachometer. The angle of attack of grinding wheel was measured by digital, three-axis accelerometer-inclinometer ATst 90. The force of pressing grinding wheel to the rail was evaluated by strain-resistive sensors M50-0.5-C3. The measurement of head rail transverse profile before and after grinding and evaluation of metal removal were carried out by a PR-03 rail profiler. The width of grinding track was controlled by ShTsTs-I-300-0.01 caliper. The surface roughness of rail sample after machining was measured by TR 200 portable instrument. Results and discussion. Based on research results of CRS, the parameters of the working equipment of designed grinding rail train, which implements the technology of high-speed rail grinding, the influence of grinding modes on the formation of the quality parameters of the machined rail surface are established, and the optimal values of the forces of pressing the grinding wheel to the rail are determined.

Simulation-based evaluation of maintenance strategies from a life cycle cost perspective

A methodology that combines simulations of long-term mechanical degradation including maintenance interventions with an assessment of the associated socio-economic impact is proposed. This development responds to an urgent need within the railway sector to enable the evaluation of maintenance strategies from a LCC perspective. The functionality of the methodology is demonstrated in an investigation of rail grinding strategies for a curve on the Swedish Iron-ore line. The results indicate a reduction in LCC of 50% when using a harder rail material (R400HT) combined with annual rail grinding as compared to a softer rail material (R350LHT) and two grinding campaigns per year.

Исследование влияния компонентов абразивного инструмента на его эксплуатационные свойства при скоростном шлифовании рельсов

Исследование влияния компонентов абразивного инструмента на его эксплуатационные свойства при скоростном шлифовании рельсов

Hunting motion of high-speed emu during cross-line operation: Mechanism and countermeasures

During the operation of the Chinese 250 km/h-level EMU, hunting occurs when the EMU crosses from Line B to Line A. Numerous tests and simulations have been conducted to investigate the mechanism of this phenomenon. Comparisons of the measured rail profiles of the two lines indicate that the left rail in Line A is higher than that in Line B at the inner rail shoulder. In addition, the top position of the right rail in Line A is approximately 2–3 mm closer to the inside than that of the right rail in Line B, with the right rail in Line A being higher than that in Line B at the inner rail shoulder. These differences cause a significant increase in the wheel–rail equivalent conicity when the EMU crosses from Line B to Line A and further cause the hunting phenomenon. Moreover, simulations and experiments are conducted to investigate the countermeasures for EMU cross-line hunting. Field test results show that both increasing the damping of the yaw damper and wheel reprofiling can improve the stability during EMU cross-line operation; however, the effect of increasing the damping of the yaw damper is limited under particularly poor wheel–rail relationship. Simulation results reveal that rail grinding of Line A referring to the Chinese 60N rail profile can also improve the stability of the EMU during cross-line operation.

Monitoring and Evaluation of High-Speed Railway Turnout Grinding Effect Based on Field Test and Simulation

Turnouts are the weak spot in high-speed rail systems, and it is simple for the phenomenon of the wheel–rail force and the carbody lateral acceleration over-limit to arise when the train passes through, which affects the service life of the rail and the running stability of the train. In this paper, the turnout with wheel–rail force over-limit and carbody lateral acceleration over-limit is selected for analysis, and the profiles of the wheel and rail are monitored. Then, the vehicle–turnout coupled multi-body dynamics model is simulated. Additionally, the portable vibration analyzer, the comprehensive inspection train, and the wheel–rail contact dynamic stress tester monitors the data and evaluates the impact of rail grinding on high-speed railway. The results of this study demonstrated that the turnout profiles are in good agreement with the standard wheel profiles following grinding, and the wheel–rail contact point and equivalent conicity both improved. When the train passes the ground turnout at high speed with and without the wheel polygonal wear, the wheel–rail force and the carbody acceleration were clearly improved. Using the wheel–rail contact dynamic stress tester, the comprehensive inspection train, and the portable vibration analyzer monitoring the changes in the carbody acceleration, the wheel–rail force and the carbody acceleration are definitely better after grinding. Similar to the pattern in the simulation, the train’s running steadiness increased by grinding.

Assessment of rail grinding maintenance surface quality and damage propagation in subsequent loading cycles for premium rail grades

Rail samples were tested under various scenarios as part of a complete analysis of the rail grinding process. Two main group of tests were performed which assessed the following: 1) preventive and corrective maintenance on fresh rail samples and 2) post-grinding tribological performance of the ground samples. The results allowed further knowledge to be acquired with regards to the performance and effectiveness of the grinding process and its effect on the surface quality of the rail samples. Results indicated a correlation between White Etching Layer and the formation of cracks and defects. Additionally, the harder grades were found to retain larger quantities of White Etching Layer upon completion of the rolling/sliding testing due to the hardness gradient between the White Etching Layer and bulk material, promoting the formation of cracks.

Fracture mechanism and control method of elastic strip of Cologne-egg fastener in the high-prevalence section of rail corrugation

Rail corrugation is a typical problem on rail surface, and its high-prevalence section is often accompanied by the fracture of fastener elastic strip. The present paper focuses on the fracture mechanism and control method of the Cologne-egg fastener elastic strip in the high-prevalence section of rail corrugation. Firstly, the numerical simulation model of wheel-rail-fastener system considering the key components of Cologne-egg fastener is completely constructed. Then, the fracture mechanism of Cologne-egg fastener is explored by comprehensively considering the resonance response and fatigue failure of the fastener elastic strip. Finally, the corresponding control methods are proposed by the passive control of rail grinding and active adjustment of fastener structure. Analysis results show that the intensified wheel-rail friction coupling vibration in the corrugation zone leads to the resonance response of the Cologne-egg fastener elastic strip, which intensifies the vibration response of elastic strip. Then, the aggravation of vibration response of the Cologne-egg fastener elastic strip leads the fatigue of the elastic strip, and the outer elastic strip is easier to fracture than the inner elastic strip on the low rail of small-radius curve. Controlling the corrugation depth before 0.16 mm or adjusting the elastic modulus of the damping rubber to be 2.20 MPa and 9.40 MPa can increase the service life of Cologne-egg fastener elastic strip.

Study on the grinding force of single grain in rail grinding based on open-type belt grinding

In the realm of machining, there exists a heightened demand for improved surface integrity of workpieces. Abrasive belt grinding presents several advantages, including a high grinding ratio, superior surface finish quality, and lower grinding temperature. Additionally, the precision placement of abrasive grains in the form of triangular pyramids further enhances the efficacy of this method. It has played an important role in the field of precision machining. Accurately predicting its grinding force is vital for improving its processing quality. In this study, an open-type belt grinding method was developed, the grinding force of triangular pyramid-shaped abrasive grains in rail grinding was analyzed and calculated using oblique cutting theory, the accuracy of the proposed model was verified experimentally, and the effects of abrasive rotation angle, wear height, cutting depth, grinding speed, and rake angle on the grinding force were analyzed, and the relevant laws were obtained. According to the findings, the grinding force displays an initial rise followed by a decline as the triangular pyramid abrasive particles' rotational angle increases. The grinding force demonstrates a linear growth in tandem with an increase in grinding depth. Furthermore, the grinding force rises proportionally with an increase in abrasive wear height. The proposed model can be used for the prediction and calculation of grinding forces of other shape abrasive grains as well.

Several tests for verification of material deterioration evaluation method of rail steel using X-ray diffraction analysis

Quantitative evaluation of rail deterioration due to rolling contact contributes to the optimization of rail maintenance such as rail grinding. A technique for evaluating rail deterioration due to rolling contact using X-ray diffraction has been reported. To use this method as a practical method for quantifying the degree of influence of rolling contact on rails, we should clarify experimentally the basic issues such as the correlation between the calculated index and the degree of rolling contact fatigue.In this study, the validity of this X-ray diffraction analysis method is verified by evaluating specimens at different loading stages via tensile and rolling tests. The results are also compared with Kernel average misorientation (KAM) values from electron back scattered diffraction. The same method was also used to evaluate rail degradation conditions for 700 million tons of passing tonnage.The following findings are identified from the above results. Dislocation density, one of the indicators obtained by X-ray diffraction, is directly related to crack initiation in rail steels. The X-ray crystallite size, which is also linked to the increase in the KAM value, makes it suitable for evaluating the degree of strain due to rolling contact.

Multidiscipline Design Optimization for Large-Scale Complex Nonlinear Dynamic System Based on Weak Coupling Interfaces

For high-tech manufacturing industries, developing large-scale complex nonlinear dynamic systems must be taken as one of the basic works, formulating problems to be solved, steering system design in a more preferable direction, and making correct strategic decisions. By using effective tools of big data mining, Dynamic Design Methodology was proposed to establish a technical platform for Multidiscipline Design Optimization such as High-Speed Rolling Stock, including three key technologies: analysis graph of full-vehicle stability properties and variation patterns, improved transaction strategy of flexible body to MBS interface, seamless collaboration with weldline fatigue damage assessments through correct Modal Stress Recovery. By applying the above methodology, a self-adaptive improved solution was formulated with optimal parameter configuration, which is one of the more favorable options for higher-speed bogies. While within a velocity (140–200) km/h at λe < 0.10, car body instability’s influence on ride comfort can be easily improved by using a semi-active vibration reduction technique between inter-vehicles through outer windshields. Comprehensive evaluations show that only under rational conditions of wheel-rail matching, i.e., 0.10 ≥ λeN > λemin and λemin = (0.03–0.06), can this low-cost solution achieve the three goals of low track conicity, optimal route planning, and investment benefit maximization. So, rail vehicle experts are necessary to collaborate and innovate intensively with passenger transportation and steel rail ones. Specifically, by adopting rail grinding treatment, occurrence probability is controlled at 85% and 5% for track conicity of (0.03–0.10) and (0.25–0.35). By optimizing routing planning, operating across dedicated lines of different speed grades can achieve self-cleaning of central hollow tread wear over time. According to the inherent rigid-flex coupling relationship, geometric nonlinearities of worn wheel-rail contact should be avoided as much as possible for HSR practices. Only under weak coupling interfaces in the floor frame can the structural integrity of an aluminum alloy car body be ensured.

An assessment method of rail corrugation based on wheel–rail vertical force and its application for rail grinding

In practice, the assessment and treatment of rail corrugation are quantitatively based on the corrugation depth. Wheel–rail vertical forces (WRVF), as a direct reflection of wheel–rail interaction, can give expression to the corrugation depth and thus serve as a key parameter for assessing the corrugation. In this paper, we propose an evaluation method for rail corrugation based on the WRVF. First, a 3D wheel–rail dynamic finite element (FE) model was developed with typical parameters of CRTS II slab track and CRH3 vehicle for high-speed railways in China. The accuracy of the model was then validated with the measured WRVF data in the field. Second, using the validated model, the time–frequency domain distribution of WRVF (vehicle speed: 300 km/h) was obtained with consideration of the corrugation wavelength in the range of 40–180 mm. The non-linear least squares method and rational equation were used to fit the function between the large value of WRVF and the corrugation depth value under the conditions of different corrugation wavelengths. Next, effects of the Pinned–Pinned resonance frequency and vibration mode on the fitted parameters were analysed, by which an indicator for corrugation treatment (grinding) was proposed. Finally, the indicator was applied in the monitoring of rail corrugation for high-speed railway lines in the field. The results show that the misjudgement rate of rail grinding decisions (using the proposed indicator) is low with the accuracy at 92.5%. The proposed method can provide a basis for the rail corrugation evaluation and grinding decisions-making.

Possibilities of manual eddy current testing for measuring the depth of contact-fatigue cracks of the surface of rolling rails

The possibility of using the eddy current method to assess the depth of cracks in the surface of rolling rails in operation for planning the work of a rail grinding train is investigated. Experimental studies of the influence of the excitation frequency and the angle of inclination of the eddy current converter, the state of the surface, the depth and angle of inclination of the surface crack on the amplitude and phase of the eddy current signal are carried out. The possibilities of the amplitude-phase method of detuning from interfering factors associated with the slope of the transducer and the curvature of the controlled surface are determined. The resolution of the flaw detector was investigated when evaluating the characteristics of two or more closely spaced cracks - a defect of the "grid" type of cracks. The depth of surface cracks in the range from 0.1 to 1.4 mm was determined by metallographic examination after eddy current control. Optimal control parameters have been experimentally substantiated and a correlation between the crack depth and the projection of the signal amplitude in the direction perpendicular to the direction of change of the interfering factor - the angle of inclination of the transducer - has been established.

Study on the Preparation and Performance of Silicone-Modified Phenolic Resin Binder for Rail Grinding Wheels.

A scheme for manufacturing heavy-duty rail grinding wheels with silicone-modified phenolic resin (SMPR) as a binder in the field of rail grinding is presented to improve the performance of grinding wheels. To optimize the heat resistance and mechanical performance of rail grinding wheels, an SMPR for industrial production of rail grinding wheels was prepared in a two-step reaction using methyl-trimethoxy-silane (MTMS) as the organosilicon modifier by guiding the occurrence of the transesterification and addition polymerization reactions. The effect of MTMS concentration on the performance of silicone-modified phenolic resin for application in rail grinding wheels was investigated. The molecular structure, thermal stability, bending strength, and impact strength values of the SMPR were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and mechanical property testing, and the effect of MTMS content on the resin properties was investigated. The results indicated that MTMS successfully improved the performance of the phenolic resin. The thermogravimetric weight loss temperature of the SMPR modified by MTMS with 40% phenol mass at 30% weight loss is 66% higher than that of common phenolic resin (UMPR), exhibiting the best thermal stability; in addition, its bending strength and impact strength were enhanced by approximately 14% and 6%, respectively, compared with those of common UMPR. This study utilized an innovative Bronsted acid as a catalyst and simplified several intermediate reactions in the conventional silicone-modified phenolic resin technology. This new investigation of the synthesis process decreases the manufacturing cost of the SMPR, liberates it from the restrictions of grinding applications, and enables the SMPR to maximize its performance in the rail grinding industry. This study serves as a reference for future work on resin binders for grinding wheels and the development of rail grinding wheel manufacturing technology.

Predicting rail corrugation in a real line by means of a fast non-linear vertical and lateral model

This work is the result of a problem of premature development of rail corrugation found on a new metro line. As urgent solutions, a rail grinding was carried out and friction modifier started to be applied. Experimental corrugation measurements have been taken periodically in this line at 60 control points since 2018, and an extensive database has been collected since then. As a second stage, a computationally efficient new model has been developed to predict corrugation growth under different running conditions. The aim of this work has been to obtain feasible solutions to delay corrugation growth in metro type lines.

Contact Mechanism of Rail Grinding with Open-Structured Abrasive Belt Based on Pressure Grinding Plate

The current research of abrasive belt grinding rail mainly focuses on the contact mechanism and structural design. Compared with the closed structure abrasive belt grinding, open-structured abrasive belt grinding has excellent performance in dynamic stability, consistency of grinding quality, extension of grinding mileage and improvement of working efficiency. However, in the contact structure design, the open-structured abrasive belt grinding rail using a profiling pressure grinding plate and the closed structure abrasive belt using the contact wheel are different, and the contact mechanisms of the two are different. In this paper, based on the conformal contact and Hertz theory, the contact mechanism of the pressure grinding plate, abrasive belt and rail is analyzed. Through finite element simulation and static pressure experiment, the contact behavior of pressure grinding plate, abrasive belt and rail under single concentrated force, uniform force and multiple concentrated force was studied, and the distribution characteristics of contact stress on rail surface were observed. The results show that under the same external load, there are three contact areas under the three loading modes. The outer contour of the middle contact area is rectangular, and the inner contour is elliptical. In the contact area at both ends, the stress is extremely small under a single concentrated force, the internal stress is drop-shaped under a uniform force, and the internal stress under multiple concentration forces is elliptical. Compared with the three, the maximum stress is the smallest and the stress distribution is more uniform under multiple concentrated forces. Therefore, the multiple concentrated forces is the best grinding pressure loading mode. The research provides support for the application of rail grinding with open-structured abrasive belt based on pressure grinding plate, such as contact mechanism and grinding pressure mode selection.

Grinding limit and profile optimization in the high-incidence section of rail corrugation in mountainous city metro

As the most common and direct control method for rail corrugation, the rail grinding can effectively improve the service life of rails, but requires scientific theoretical guidance to achieve the efficient grinding. Therefore, it is necessary to formulate corresponding grinding limits and profile optimizations for different characteristics of rail corrugations. According to the on-site investigation of rail corrugation in the overlapping section of horizontal-vertical curves of the mountainous city metro, the corresponding dynamic model of vehicle-track system is constructed. Through the safety evaluation of the dynamic characteristics of the vehicle-track system, the safety limit of the rail corrugation grinding is preliminarily determined. Then, based on the wheel-rail friction-coupled vibration theory, the finite element model of the wheel-rail system is built. By exploring the wheel-rail friction-coupled vibration characteristics in the corrugated section with typical characteristics, the optimal limit of rail corrugation grinding is further confirmed. Finally, the treatment effects before and after rail grinding are compared using the profile optimization. Results show that when the corrugation wavelengths in the overlapping section are 30 mm, 40 mm, 50 mm, 60 mm, and 70 mm, the safety limits for rail corrugation grinding are 0.03 mm, 0.04 mm, 0.05 mm, 0.08 mm, and 0.15 mm. For the typical rail corrugation with the wavelength of 50 mm, the optimal limit of the rail corrugation grinding is 0.02 mm. Moreover, the earlier the rail corrugation is polished, the better the relative optimization effect is, but it is necessary to consider the grinding cost for targeted grinding.