Wheel Profile Research Articles

A form-grinding wheel optimization method for helical gears based on a PSO-SVM model

A gear form-grinding optimization method is proposed to obtain an optimal profile of a form-grinding wheel by solving a transcendental equation of the contact line between a form-grinding wheel and a helical gear workpiece. Since the equation of the contact line is transcendental, the relationship between the installation angle of the form-grinding wheel and the shape of the contact line cannot be represented by explicit functions, which makes it difficult to obtain the optimal profile of the form-grinding wheel. An optimization method of the contact line between the form-grinding wheel and the gear is proposed using three evaluation parameters that are the overrun, the shift, and the offset. Some gear form-grinding performances, such as machining stroke, tooth deviation, and grinding chatter, can be quantitatively described using those evaluation parameters. Further, a method for optimizing evaluation parameters is proposed, which uses a particle swarm optimization-support vector machine (PSO-SVM) model with the advantage of small-sample robustness to solve evaluation parameters. The PSO-SVM model is trained under the condition of different installation angles of the form-grinding wheel as the input and the evaluation function as the output. The R-squared value of the overrun is 0.986 that vilidate the high accuracy of the PSO-SVM model. Gear form-grinding test results show the proposed method can effectively improve grinding accuracy.

An optimized calculation method of the grinding wheel profile for the helical flute forming grinding

An optimized calculation method of the grinding wheel profile for the helical flute forming grinding

An Analysis of Power Friction Losses in Gear Engagement with Intermediate Rolling Elements and a Free Cage

Currently, mechanical gears with cycloid engagement are increasingly used in mechanisms along with involute ones. In modern drive mechanisms, using pin gears and gears with intermediate rolling elements (IRE) is widespread, which simultaneously use cycloid gears. To a greater extent, pin gears are now being investigated, but IRE gears have their undeniable advantages. Many works are devoted to the study of cycloid toothing for certain gears, but the efficiency, especially that of IRE gears, has practically not been investigated. Therefore, the analysis of power losses in the engagement of a gear with IRE and a free cage (IREFC) is relevant. In this analysis, the authors of the work have used laws of mechanics, methods of energy flows and a secant normal. Mathematical expressions have been obtained to estimate slip speeds and power friction losses in the engagement of a gear with IREFC, and a formula has been derived to determine the efficiency of a mentioned mechanical transmission. The calculation of slip speeds and power losses at the points of contact of a rolling element with cycloid profiles of wheels for selected initial parameters of a gear with IREFC has been presented. The friction power and the overall efficiency of the entire gear engagement have also been calculated. This work shows that power friction losses at the points of contact of a rolling element with cycloid profiles of tooth wheels of a gear with IREFC are not the same. The friction power in the contact of a rolling element with a cycloid profile of a cam is an order of magnitude higher than the friction power in the contact of a rolling element with a cycloid profile of a crown.

ТЕХНОЛОГИЧЕСКИЕ МЕТОДЫ УВЕЛИЧЕНИЯ ДОЛГОВЕЧНОСТИ КОЛЕС ПАССАЖИРСКОГО ЖЕЛЕЗНОДОРОЖНОГО ВАГОНА

The cut of passenger cars due to wear damage to the rolling surface of the wheelset in 2022 is considered. It is found out that the most typical damage is a shelled tread. An analysis of the methods for restoring the rolling profile of wheels showed that the wheel milling with an end mill can be used as a promising one. To assess the effectiveness of the method, metallographic and tribological studies of wheel samples subjected to turning and milling are compared. According to the study results, it is found that when machining samples of wheel steel by end milling, their wear resistance is 22% higher, compared with samples machined by turning, the wear rate of samples of rail steel is lower in a friction pair with milled samples than with turned samples due to a decrease in the friction factor of milling samples.

Wheel wear prediction for high-speed trains by considering wheel-rail elastic deformation

Wheel-rail geometric parameters are crucial for determining wheel wear in high-speed trains. Under the action of a wheel-rail load, both the wheel and rail suffer elastic deformation, which affects the wheel-rail contact relationship and further influences the wheel profile and its evolution. In this study, a field test was conducted on a high-speed train operating at 250 km/h, and the worn wheel profiles and wear curves were continuously measured for one reprofiling cycle. Subsequently, a vehicle dynamics model is built using a wheel wear prediction model based on the integrated USFD wear algorithm. In this model, the finite element model of the wheel-rail contact is considered. The wheel-rail geometric parameters are obtained by determining their elastic deformation through the finite element method, which considers the effect of three parameters: the track gauge, back-to-back space of the wheelset, and rail cant. After considering the wheel-rail elastic deformation, the track gauge decreases from 1435 to 1434.5 mm, the back-to-back space varies from 1353 to 1352.3 mm, and the rail cant changes from 1:40 to approximately 1:37. Finally, the simulation and experimental results are compared, revealing that the wheel-rail elastic deformation has a significant impact on the wheel wear after the vehicle travels 150,000 km. The wear depth and wheel-rail equivalent conicity after considering the elastic deformation are closer to the measured results.

Wheel profile optimization for intercity EMUs based on the Gaussian function correction method

Intercity EMUs are prone to wheel flange wear and tread wear due to the high operating speed and many small radius curved tracks. The problems caused by wheel wear have seriously affected the safety of high-speed railway operations in China. In this paper, based on the original LMA wheel profile, the Gaussian function correction (GFC) method is proposed to design the wheel profile. The GFC method mainly changes the root region of the wheel flange, to enhance the curve passing performance and reduce wheel wear of the vehicle. The optimal profile is optimized by the Kriging surrogate model (KSM) and the whale optimization algorithm (WOA). The wheel-rail contact characteristics, dynamic characteristics and the wheel wear of the wheel profiles before and after optimization are simulated and analyzed. The results show that the equivalent conicity of the optimized profile is reduced; the critical speed is increased by 9.3 km/h, the lateral ride index and comfort index of the vehicle are further reduced. The curve passing performance is also improved, the wheel-rail wear of the optimized profile is further reduced and the maximum wear depth of the wheels before and after optimization is 43.4e-9m and 34.1e-9m on the curved track with a radius of 500m, which is reduced by 21.43%. This method provides a reference and basis for wheel profile design and profile re-profiling of intercity EMUs.

Addressing perceptions regarding the influence of relative hardness on wheel/rail performance

An age-old debate amongst railway practitioners has revolved around the potential effects of increased wheel and/or rail steel hardness on corresponding damage rates. In specific, whether raising the hardness of one partner will have a deleterious impact on the wear rates of the other. This paper addresses that question through two methods.• Laboratory and field evidence on performance of rail/wheel pairs of differing hardness is reviewed.• A survey was sent to railway practitioners around the world to collect perceptions on how relative hardness might influence wheel-rail performance. These perspectives are then addressed using principles of contact mechanics, fracture mechanics and general material characteristics.Through the review of available evidence, and application of fundamental principles, it can be seen that increasing the hardness of one partner in the wheel-rail system is not expected to have a direct or causal effect on the wear rates experienced by the other. However, increasing the hardness of one or both partners does motivate increasing care in maintaining wheel and rail profiles, along with other maintenance considerations.

Theoretical study on wheel wear mechanism of high-speed train under different braking modes

The high-speed train wheel wear problem persists throughout the whole service cycle, including the traction-braking stage, constant-speed stage, acceleration and deceleration stage, and so on. This article focuses on the wheel wear of high-speed trains under various braking modes. Firstly, high-speed motor cars and trailers are created, and the two are linked by the coupler buffer device, and the former considers detailed gear transmission system. A comprehensive wheel wear prediction process is then established based on the vehicle model, wheel-rail contact model, wear model, and wheel tread update strategy. Secondly, vehicle model and wheel wear prediction procedure are validated using the measured dynamic data and worn wheel profile. Thirdly, common braking modes and emergency braking modes are used for the braking process of high-speed trains. Finally, wheel wear and wear mechanism of high-speed trains during braking process is revealed. The results demonstrate that with the increase of braking mode level, the amplitude of longitudinal creepage also increases synchronously, while lateral creepage and spin creepage do not change significantly. According to wheel wear depth under different braking processes, the order from large to small is emergency braking mode >8-level common braking mode >6-level common braking mode >4-level common braking mode >3-level common braking mode >B1-level common braking mode. Furthermore, with the increase of rail slope, wheel wear is increasing during braking process. With the increase of friction coefficient, wheel wear depth decreases gradually during braking process.

A case study of the economic reprofiling method for a high-speed train's wheel tread in the frequent contact area

The wheel-rail contact geometry strongly affects the dynamic running behavior of a railway vehicle, so it is a key factor for its operational safety. Although wear in the wheel-rail contact is generally inevitable, a particular problem is the occurrence of nonuniformly distributed wear, which changes the wheel profile and thereby often leads to a deterioration of the vehicle's running behavior. Therefore, the restoration of the wheel profile, known as reprofiling, is an important maintenance action for ensuring operational safety. The exact restoration of the original wheel profile, however, often requires the removal of a high volume of material, which can drastically shorten the service life of the wheel. An incomplete restoration of the wheel profile, which requires the removal of less material, extends the wheel's service life and is therefore also known as “economic reprofiling”. Nevertheless, an incompletely restored wheel profile, too, must still fulfill the same requirements as the original profile with respect to the vehicle's running behavior and thereby to its operational safety. While previous work mainly dealt with the impact of flange wear, the present study focuses on the wheel tread frequent contact area (WTFCA). This study presents a long-term wheel wear prediction model for a high-speed train and proposes a design method for the wheel profile in the WTFCA for economic reprofiling. After optimizing the key factors, the utilization of the wheel profile for economic reprofiling can comprehensively consider the dynamic performance, wear behavior, and economic performance of the vehicle, which can be applied to guide the maintenance of the wheel profile.

Force modeling of vertical surface grinding considering wheel-workpiece contact geometry

Vertical surface grinding (VSG) is an effective method that can adapt to multiple machining tasks, including stock removal machining to get high productivity and finish machining to obtain high-quality surfaces. Force prediction can reveal some mechanisms in the VSG process, conducing to the improved machining quality and efficiency. This paper aims to develop a novel analytical force model considering the actual wheel-workpiece contact geometry (WWCG). In the modeling process, the cup grinding wheel was divided into many micro-cutting layers along the wheel axis, and the expressions of geometrical-kinematic parameters were derived to characterize the material removal at different positions of the primary grinding zone (PGZ). A single-grain grinding force model was proposed based on chip formation and plastic pile-up mechanisms from an energy perspective. Based on the analysis of multiple-grain interactions at each micro-cutting layer, equations of the local and total grinding forces in the VSG process were then derived by synthesizing the single-grain forces. Findings show that the developed model could accurately predict the magnitudes of total grinding forces and provide the distributions of local grinding forces. The WWCG variation could significantly affect the grinding forces by altering the material removal rate of different micro-cutting layers. This work provides a new method for predicting grinding forces and theoretical guidance for optimizing machining parameters and tailoring the edge profiles of cup grinding wheels to adapt to specific machining tasks.

Профіль ободу коліс вантажного вагона з перспективними візками для умов спільної експлуатації на українських і європейських залізницях

To solve the important problem of speeding up the integration of Ukraine into the European railway transportation, an interest has recently grown in the introduction of automatic car transfer from one track gauge to another using gauge-changeable wheelsets, thus dispensing with truck exchange or transshipment and thereby significantly shortening the delivery time. However, the combined operation of trains on the Ukrainian (1,520 mm gauge) and European (1,435 mm gauge) railways calls for the compatibility of the wheel-rail contact pair on both railways: R65 rails and a cant of 1/20 in Ukraine and UIC60 rails and a cant of 1/40 in Europe. The goal of this work is to develop a wheel profile for a freight car with prospective 18-7020 trucks for combined operation on the Ukrainian and European railways and predict the ride performance of a car with that wheel profile and its dynamic interaction with rails on both railways. An investigation was conducted into the wheel?rail interaction indices and the ride performance of a freight car with prospective 18-7020 trucks and wheels with existing profiles. It was shown that it is expedient to develop a new wheel profile to improve the service compatibility of the Ukrainian and European networks. A number of new wheel profiles were constructed, the efficiency of each profile in terms of dynamic stability at service speeds and wheel flange wear on the Ukrainian and European railways was calculated, and a compromise profile, ITM-73ES, was chosen. It was shown that the use of the chosen profile in a car with 18-7020 trucks will offer a high dynamic performance and improved indices of wheel?rail interaction for both truck gauges.

Grinding wheel profile design and temperature field analysis of the pinion for internal meshing gear with curve configuration

To further develop the performance testing and practical application of internal meshing gear with curve configuration, the grinding manufacturing method is proposed in this paper. Based on basic principle of internal meshing gear with curve configuration, Newton’s iterative method is used to derive the contact line condition equation during the process of form grinding. Then, the spatial coordinate transformation relationship of the pinion is established, and normal profile of the grinding wheel is derived. An improved transversal algorithm is proposed to analyze the tooth profile error after form grinding simulation, and the results verify the correctness of the designed grinding wheel. A meshing model with single tooth is established. The effects of different parameters on the grinding temperature field under dry and wet grinding conditions are simulated respectively, which will be helpful to the optimization and control of temperature in grinding process. The research results lay the essential theoretical foundation and engineering analysis for practical form grinding applications of the new internal gears. Further study on experimental analysis of grinding manufacturing process of the new tooth surfaces will be carried out.

Investigation of dynamic gauge widening in small radius curves and its impact on lateral wheel-rail contact forces

In this paper, the lateral interaction between a rail vehicle and the track is investigated during cases of an occurrence of dynamic gauge widening. This is composed of the nominal track gauge, wear of the rail profiles and track widening due to wheel-rail forces on sections of curved track. A multibody simulation model is used to investigate the various influencing parameters. This model not only analyses the single rail’s lateral displacement but also tilting. Furthermore, the simulation of rail pads with adjustable stiffnesses is enabled. The resulting different contact points between the wheel and rail are represented, affecting the wheel-rail contact forces. The results reveal that changes in contact geometry caused by rail tilting depend strongly on the specific wheel and rail profiles. This is illustrated by comparing a new rail profile with a heavily worn rail profile. Particular attention is also paid to the distinction between leading and trailing wheelsets. Finally, the model is validated using measured wheel-rail forces and rail head movement, as measured on the track. A better understanding of dynamic track widening can improve the running behaviour of the wheelset on small radius curves, help protect against derailment and reduce wear on the wheel and rail.

Impact of wheel profile evolution on the lateral motion characteristics of a high-speed vehicle navigating through turnout

The wheel-rail contact asymmetry on the left and right sides of the wheelset while navigating high-speed vehicles through turnouts can lead to lateral motion of the wheelset, ultimately resulting in substantial vibrations in the vehicle system. This study employs the trace method to examine the changing pattern of the wheel-rail equivalent conicity in the turnout area as the wheel profile evolves. A coupled system dynamics model containing flexible turnouts is established. Specifically, the model examines the lateral position of wheel-rail contact points, the lateral motion of the wheelset, and the lateral vibration acceleration of the vehicle system. The study indicates that the lateral motion characteristics of high-speed trains passing through turnouts are influenced by the degree of wheel wear. When the wheels are slightly worn (for mileage below or equal to 100,000 km), the lateral dynamic responses of the vehicle system are affected by the inherent structure of the turnout. When the wheels are severely worn (for mileage above or equal to 150,000 km), the lateral dynamic response of the vehicle system is no longer affected by the inherent structure of the turnout.

Design for manufacturing of a spur gears profile modification based on the static transmission error for improving the dynamic behavior

This study presents a novel iterative algorithm for obtaining an improved profile modification for spur gears based on minimizing the peak-to-peak static transmission error. Two improved profile modifications, obtained with different initial constraints applied to the tooth profile, were calculated and characterized. The static behavior of the gears was analyzed using a finite element model, by which the modifications were compared considering the maximum contact pressure and peak-to-peak static transmission error. The dynamic behavior of the gears was analyzed using a lumped parameter model. The dynamic overload and the dynamic transmission error were evaluated under several working regimes. The grinding wheel profiles used to realize the proposed profile modifications and the total volume of material removed were calculated using a CAD model. The results showed that the proposed modifications lead to a significant improvement in the static and dynamic behavior of the transmission by reducing both the maximum dynamic overload and meshing noise. The profiles of the grinding wheel were found to be accurately represented by polynomial functions, thus a feasible manufacturing process can be obtained. The total volume of material removed was lower than that produced by commonly adopted profile modifications, thus reducing material waste and increasing the productivity of the manufacturing process compared to standard profile modifications.

A grinding profile design method for rails in the switch area considering a representative set of wheel profiles

A grinding profile design method for rails in the switch area considering a representative set of wheel profiles

Applicability Verification of Restoration by Welding to Extend the Lifetime of Railway Wheel

Railway wheels, when subjected to wear beyond their designated usage standards due to the operation of railway vehicles, are traditionally managed through a turing maintenance method. This process involves turing the entire worn portion to secure the requisite cross-sectional shape. This approach often leads to disposal after just 2 to 3 turing maintenance cycles. Excessive turing, extending beyond the worn parts, can cause the wheels to fail to meet railway operating specifications. Discarded railway wheels, which contain a high carbon content essential for driving performance, are not repurposed but are instead entirely stockpiled. This research introduces a novel welding restoration technology for railway wheels, targeting the flange portion, a principal area of wear. Utilizing submerged arc welding techniques, this method enables the localized repair of worn parts, minimizing the turing thickness and thus extending the useful life fo railway wheel. To evaluate the on-site applicability and dependability of this welding restoration method, real rail vehicle driving tests were conducted using both conventionally turned and welding-restored railway wheels. Analysis of the wheel profiles substantiated that the welding restoration method delivers mechanical performance comparable to that achieved by traditional turning maintenance.

Wayside wheelset lateral motion detection and vehicle hunting instability evaluation

Wheel profile wear, or bogie suspension failure will result in hunting instability of the vehicle system which will lead to dramatic changes in the lateral motion of the wheelset. The occurrence of hunting instability will worsen the ride performance of the vehicle or even cause the danger of wheelset derailment. Thus, the in-time and effective detection of wheelset lateral motion is very important for the vehicle hunting stability evaluation. By installing a certain amount of displacement sensors on the rail side along the track and detecting the distance between the wheel and rail when the wheelset passing by, the lateral displacements of the wheelset in measuring points can be obtained. The detection method of wheelset lateral motion by the wayside is studied, which includes the measuring principle, structure design, sensor installation, data acquisition and data analysis, and the application of the method to on-site detection for typical instability cases are demonstrated. At the same time, innovate on the existing on-board hunting instability monitoring method, proposed an evaluation method of hunting instability for wayside lateral movement monitoring system. The results show that: installing 20 eddy current sensors on both sides of the straight track to measure the lateral displacement of the wheelset can meet the requirement of detecting the vehicle hunting instability. At the same time, analyzing the measurement data and fitting the maximum value of the signal collected by each sensor can obtain the lateral trajectory of the wheelset. The wheelset lateral displacement can be used to monitor the occurrence of vehicle hunting instability if periodic motion is detected. The amplitude of the motion can determine the hunting instability level, and the frequency can be used to describe the wheel wear level and calculate the wheel/rail contact equivalent conicity. This method is able to provide a reliable data support for the vehicle operation safety. The proposed monitoring method and monitoring index are also of reference value to the development of other wayside hunting instability monitoring systems.

Testing the wear of wheelsets of EN97 series vehicles in terms of geometrical parameters of the wheel profile in two-year operation

The article presents the results of wheel wear tests of selected EN97 series electric multiple units. In the tests carried out on the 14 vehicles mentioned above, which were driven on the same route, geometrical parameters of the profile of all wheels were recorded during periodic inspections. The analyzed data concerned the period of over two years of use, when the vehicles were delivered from the manufacturer to the carrier as new. In the form of graphs, cases of exceeding a given parameter in relation to the requirements set in the Maintenance System Documentation are presented, broken down into individual wheelsets. The article presents the results of operational tests, which show which wheel set parameters (wheel diameter, rim steepness, rim thickness, rim height, etc.) are most often exceeded and which are least. The analyzes of the geometric parameters of the wheel profile on the tested group of vehicles, which were used on the same route in the same period, clearly prove that the parameters most often exceeded are wheel diameter and rim steepness. These two exceeded parameters were the basis for turning the wheelsets.

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.