Wheel Shape Research Articles

High-precision MRI of liver and hepatic lesions on gadoxetic acid-enhanced hepatobiliary phase using a deep learning technique.

The purpose of this study was to investigate whether the high-precision magnetic resonance (MR) sequence using modified Fast 3D mode wheel and Precise IQ Engine (PIQE), that was collected in a wheel shape with sequential data filling in the k-space in the phase encode-slice encode plane, is feasible for breath-hold (BH) three-dimensional (3D) T1-weighted imaging of the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI in comparison to the compressed sensing (CS) sequence using Advanced Intelligent Clear-IQ Engine (AiCE). This retrospective study included 54 patients with focal hepatic lesions who underwent dynamic contrast-enhanced MRI. Both standard HBP images using CS with AiCE and high-precision HBP images using modified Fast 3D mode wheel and PIQE were obtained. Image quality, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were evaluated using the Wilcoxon signed-rank test. p values of < 0.05 were considered to be statistically significant. Scores for image noise, conspicuity of liver contours and intrahepatic structures, and overall image quality in high-precision HBP imaging using modified Fast 3D mode wheel and PIQE were significantly higher than those in HBP imaging using CS and AiCE (all p < 0.001). There was no significant difference in the presence of artifact and motion-related blurring. There were no significant differences between the sequences in SNR (p = 0.341) or CNR (p = 0.077). The detection rate of focal hepatic lesions was 71.4-85.3% in CS with AiCE, and 82.2-95.8% in modified Fast 3D mode wheel and PIQE. A high-precision MR sequence using a modified Fast 3D mode wheel and PIQE is applicable for the HBP of BH 3D T1-weighted imaging.

Detectability of residual stress anomalies in railway wheels with different geometries subjected to thermal overload based on back gauge change

Temperature increases of railway wheels due to frictional braking on the running surface (wheel tread) can lead to maintenance challenges such as tread wear and thermal cracking. While heating within the anticipated design range should not adversely affect the structural safety of the wheels, excessive temperature rises resulting from brake system failures can induce tensile residual stresses in the rim, potentially leading to wheel fracture. Detecting wheels with abnormal residual stresses is therefore crucial for railway safety, and monitoring residual displacements in the rim due to changes in circumferential residual stresses is an implementable approach. However, the shape of the wheel web varies, and the displacement response to thermal input differs depending on the wheel geometries. This study aims to explore general deformation behaviours related to wheel shape and elucidate the relationship between shape and heat resistance. The elastic-plastic finite element analysis employing simplified intense thermal input revealed that residual deformation after excessive thermal loading consistently results in back gauge expansion, although the deformation and stress responses differ based on the web geometry. Differences in heat resistance are indicated by the variation in the temperature at which compressive yielding due to thermal stress occurs, depending on the web shape. The residual stress detectability of each wheel is determined based on the principle that greater residual displacement at lower stress indicates higher anomaly detectability.

Design and analysis of a mobile robot with novel caster mechanism for high step-overcoming capability

The mobile robot market is experiencing rapid growth, playing a pivotal role in various human-centric environments like restaurants, offices, hotels, hospitals, apartments, and factories. However, current differential-driven mobile robots, employing conventional casters and wheel motors, encounter limitations in surmounting uneven surfaces and high steps due to constraints caused by wheel and caster dimensions. While some robots address these challenges by incorporating optimized wheel shapes and additional motors, this invariably leads to an increase in both size and cost. This research introduces an innovative solution; a novel caster-wheel mechanism designed to enhance the high-step overcoming capability of mobile robots without necessitating alterations to their overall size and structure. By incorporating a sub-wheel linked to a passive joint, the driving force is effeciently converted into a vertical force, thereby empowering the mobile robot to navigate obstacles 85% larger than its caster-wheel radius. Crucially, this innovative caster can be seamlessly manufactured and integrated, offering the potential for widespread adoption as a replacement for conventional casters. Validation through comprehensive simulations and experiments conducted on a prototype robot has been presented in this article, demonstrating its effectiveness even at a robot velocity of 0.1 m/s. This pioneering solution holds significant promise for diverse applications across various mobile robot configurations, presenting a compelling avenue for further exploration and implementation in the field.

Effect of the Axial Profile of a Ceramic Grinding Wheel on Selected Roughness Parameters of Shaped Surfaces Obtained in the Grinding Process with a Dual-Tool Grinding Head.

The use of CNC equipment that integrates several machining operations eliminates downtime due to changes in setup and clamping of workpieces in more than one machining device. A review of CNC equipment and tools known from the literature and from manufacturers' offerings indicates that new technical solutions are being developed to integrate two or more technological operations. However, these examples have numerous limitations and are mostly not suitable for machining surfaces with complex shapes. An example of such solutions is the use of a dual-tool grinding head, which integrates the process of rough grinding with a ceramic grinding wheel and finish grinding with a flexible grinding wheel. Unfortunately, it has the disadvantage of being limited by the angular shape of the ceramic grinding wheel, making it unable to adapt to the complex geometries of the shaped surfaces being ground. The need to overcome this limitation became the motivation for the research work described in this article. By means of experimental research, it was verified what effect the radial outline on the periphery of a ceramic grinding wheel realized by rough grinding would have on the surface roughness parameters obtained in the process of grinding shaped surfaces. For this purpose, grinding processes using a ceramic wheel with a conical and radial outline were compared. The result of the study was a summary of the surface roughness parameters Sa, St, Sq, Spk, Str, and Sds obtained after two-stage machining (rough and finish grinding). The obtained analysis results showed that changing the axial outline of the ceramic grinding wheel makes it possible to significantly expand the range of applications of the dual-tool head without negatively affecting the quality of the machined surface. Thus, such an improvement will make it possible to increase the applicability of the head by grinding shaped surfaces with a radial profile of curvature.

Performance improvement of the self-power control valve based on digital twin technology

Providing stable energy for intelligent pipe network systems is a complex problem. Ball valves are widely used in intelligent pipe network systems, and a self-power control valve is designed by integrating a flow-matching wheel in the ball valve. While the spool is throttling the fluid, a part of the energy can be extracted from the fluid and converted into the power. In order to optimize the energy capturing characteristics of the self-power control valve, the shape of the flow-matching wheel must be designed to form a precise match with the valve cavity. In this paper, a lightweight digital twin of the self-power control valve is developed using an agent model. Based on this, an optimized design method for the flow-matching wheel that can dynamically take into account the operating conditions of the valve in real time, is proposed by combining the agent model with the dynamic data from multiple sensor sources. The research results show that after the twin optimization of the flow-matching wheel, the average value of the energy capturing efficiency is improved by 3.21 % compared to the pre-optimization; the average value of the output power is improved by 20.57 % compared to the pre-optimization.

Surface topography prediction of slider races using formed grinding wheel shape and material removal mechanism

Compared with the roughness, the three-dimensional (3D) topography parameters, surface microstructure geometric characteristics and other information can more fully evaluate the grinding quality of the slider raceway surface. In this paper, based on the 3D topography model of the abrasive particle distribution on the surface of the formed grinding wheel, the material removal mechanism between the abrasive particle and the raceway surface is analyzed. With the undeformed chip thickness distribution model as the intermediate variable, the 3D topography model of the slider raceway surface is established, and the model verification is carried out from the roughness and the geometric characteristics of the surface microstructure, respectively. At the same time, the surface microstructure is extracted from the topography model, and the effects of different grinding process parameters on the geometric characteristics such as the height to width ratio, depth to width ratio and distribution density of groove, convex peak and peak valley structures are studied. Results are shown that AS,TH increase from [0.05 0.6 μm] to [0.25 0.8 μm] and FGH grows from [0.11 1.05 μm] to [0.5 1.61 μm] when the grinding depth rises from 1 μm to 4 μm. AS, TH are firstly decreased from [0.17 0.61 μm] to [0.08 0.52 μm] and then increased to [0.26 0.78 μm], and the FGH declines from [0.34 1.01 μm] to [0.16 0.86 μm] and then increases to [0.51 1.38 μm] with the feeding speed is in [25, 28 m/min]. In addition, in the range of grinding wheel linear velocity [28, 34 m/s], the AS,TH decreases from [0.19 0.81 μm] to [0.1 0.55 μm] and the FGH decreases from [0.55 1.6 μm] to [0.2 1.1 μm]. This can prepare for the subsequent research on the impact of the topography characteristics on the friction coefficient and wear amount of the slider raceway surface.

Role of catalyst topology in methanol synthesis

AbstractMethanol synthesis is carried out in a catalytic, packed bed reactor, where the shape and size of catalyst play a critical role in dictating overall reactor performance. In the current study, the effect of five different catalyst shapes including cylindrical, ring, trilobe, wagon wheel, and spherical on the reactor performance was investigated by conducting particle‐scale computational fluid dynamics (CFD) simulations. The predictions of pressure drop, velocity, temperature, reactant distribution and product yield were analyzed. When the performance of the simulated shapes was compared at the same tube Reynolds number of 50,000, internally contoured shapes (wagon wheel and ring) resulted in 40% higher pressure drops due to the tortuous flow path. However, the shape with internal void provided access for the reactant to reach the internal part of catalyst, resulting in higher yield produced per volume of catalyst. The wagon wheel shape produced 15% and 5% more yield per volume against the cylindrical shape and trilobe, respectively. The performance of the wagon wheel can be attributed to the lower diffusion limitation due to higher surface area available for reactant to penetrate the internal part of the catalyst.

Evaluation of parametric sedan wheel hub based on Kansei Engineering and regression analysis

&lt;p&gt;&lt;strong&gt;Purpose:&lt;/strong&gt; Parametric design has become one of the most important means of sedan design. The purpose of this paper is to construct a linear regression model to explore the matching relationship between Kansei words and the morphological elements of sedan wheels and to incorporate perceptual factors into the rational thinking of parametric wheel hub design. &lt;strong&gt;Design/methodology/approach:&lt;/strong&gt; To forecast the matching relationship between wheel shape design features and semantics, this research offers a multiple linear regression model. First, using sample similarity matrix data analysis and offline research, 20 typical samples of car wheels were collected. Third, the wheel shape design elements are obtained by applying the semantic difference (SD) method to four groups of users’ evaluation data on the perceived words of the car wheels. Firstly, the wheel shape is divided into six basic features and seventeen subdivided features using morphological analysis. The collected car wheel samples are then researched and coded. Ultimately, a multiple linear regression model is built utilizing shape coding matching to the styles to direct the wheel parametric design process, yielding sedan wheel design schemes with various semantics of style. &lt;strong&gt;Findings:&lt;/strong&gt; The results show that the regression models can provide good prediction performance (R&lt;sup&gt;2&lt;/sup&gt; values are greater than 0.7). This study shows that the use of multiple regression models can accurately and cost-effectively predict the wheel hub morphological elements that meet the user’s perceptual needs through morphological elements and Kansei words. &lt;strong&gt;Originality/value:&lt;/strong&gt; This paper is the first to use a multiple regression model to predict a parametric wheel shape that fits the user’s sensibility, which helps the user to present and feel the design scheme in a digital environment. The different wheel hub schemes generated by parametric design can be virtually displayed in the metaverse, helping users and designers to carry out more convenient scheme selections.&lt;/p&gt;

A study of precision grinding of micro-pitch internal thread for planetary roller screw mechanism

Planetary roller screw mechanism (PRSM) is a new type of precision-heavy-duty threaded transmission mechanism. The thread profile accuracy directly determines the transmission accuracy and bearing capacity of PRSM. The PRSM nut has characteristics such as micro-pitch, hard tooth surface, and small aperture inner surface forming, and its precision grinding is a huge challenge. In this study, a systematic experimental study on the precision grinding of micro-pitch internal threads of PRSM was conducted, including grinding wheel dressing, grinding wheel installation, and grinding process parameters, and a numerical model for the PRSM nut grinding with multiple errors such as center distance error and installation angle error was established, aiming to explore the relationship between grinding wheel dressing-installation-grinding process parameters and the profile accuracy of micro-pitch nuts. The results show that the dressing amount has a significant impact on the shape of the grinding wheel. The installation angle of the grinding wheel and the linear velocity of the grinding wheel have a greater impact on the internal thread profile, and corresponding optimal parameter combinations are proposed. This study provides support for efficient and precise machining of micro-pitch PRSM nuts in engineering practice.

Assessment of residual stresses in railway rails using ultrasonic and Barkhausen noise techniques

Residual stress, a factor affecting the fatigue and fracture characteristics of rails, is formed during the processes of fabrication and heat treatment, and is also generated by shrinkage/tension due to the temperature differences and vertical loads on wheels due to the weight of vehicles. Moreover, damage to rails tends to accelerate due to residual stress caused by the continuous increase in the number of passes and the high speed of passing vehicles. Because this can have a direct effect on safety accidents on railroad rails, having a technique to evaluate and analyse the residual stresses in rails accurately is very important. In this paper, firstly, residual stresses applied in rails were evaluated using longitudinal critically refracted (LCR) wave. Non-destructive stress measurement using ultrasonic techniques is based on calculation of the acoustoelastic coefficient obtained from the relationship between material stress and LCR wave velocity. This is because LCR waves exhibit a relatively large change in flight time in relation to a change in stress compared to other ultrasonic modes. Barkhausen noise technique is also very suitable for measuring residual stresses on railway rails, which are ferromagnetic materials. Tensile and compression tests were performed with the specimens extracted from the inspection object, and the difference between the ultrasonic speed and the magnetization amplitude according to the applied stress was measured. Then, the feasibility of calculating the internal stresses in railway rails using the reference data obtained from the extracted specimens was determined, and the reliability of each method was verified. Furthermore, based on these results, the difference in the results for the loads asymmetrically applied according to the wheel shape was analysed by measuring for each part of new and used rails.

First Reportof Colletotrichum fructicola Causing Anthracnose on Glycine max in China.

Soybean (Glycine max L.) is one of the important oilseed and vegetable crop worldwide and provides the main source of vegetable oil and proteins for human and livestock (Hartman et al. 2011). In October 2021, approximately 35% of soybean pods suffered from anthracnose in the farmer's field in Chongzhou, Sichuan Province, China (103°40'12"E, 30°37'48"N), and the occurrence area accounted for about 3.3 hm2. Symptoms of soybean were characterized by yellow spots at the initial stage, gradually expanded into dark brown spots, and eventually amounts of small black particles were densely arranged in the wheel shape on dead spots. Diseased spots of soybean pods were cut into pieces and sequentially sterilized in 75% alcohol for 30 s, 4% sodium hypochlorite for 30 s, sterile water for 3 times. After that, these pieces were placed on potato dextrose agar (PDA), and incubated at 25±2°C in the dark for 5-7 days. Single spore was separately picked and transferred to a fresh PDA plate to obtain pure culture isolates. Total six pure isolates were collected, and among them the hyphae of representative isolate 8-B were initially white, turned grey gradually on PDA medium, and the colonial reverse were radiating, whorled or a mixture of both. Conidia of 8-B were septate, hyaline, unicellular, cylindrical, obtusely rounded at both ends with 1 or 2 oil balls inside, and 10.5-17.6 µm in length and 7.0 µm-3.6 µm in width (n=100). The conidial appressoria were brown subspherical, 6.9 µm-13.3 µm in length and 5.6 µm-10.1 µm (n=50) in width. Based on morphological and cultural characteristics, the isolate 8-B was tentatively identified as Colletotrichum gloeosporioides species complex（Weir et al. 2012). To test pathogenicity,the mycelial plugs were inoculated on 20 detached soybean pods at full seed (R6) stage, and three areas of each pod were lightly scratched using a needle prior to inoculation. As controls, the PDA plugs were attached to the pinned-treated pods. Three independent replicates were conducted for control and inoculated pods, respectively. All pods were incubated in a greenhouse at 25 ± 2°C with a relative humidity of approximately 90%. After 4-5 days post-inoculation, typical anthracnose lesions were observed on the inoculated pods while the control pods remained healthy only with small wound spots. The pathogen re-isolated from all the inoculated pods were morphologically identical to the inoculation isolate (8-B). For further molecular verification, the six gene fragments including the internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase 1 (CHS-1), actin (ACT), β-tubulin 2 (TUB2) and calmodulin (CAL) were amplified and sequenced (Weir et al. 2012, Damm et al. 2012), and the obtained sequences were deposited in GenBank (Accession numbers ON960278, ON685214, ON964475, ON974476, ON685215 and ON964477, respectively). All six gene sequences of 8-B had a high identity to C. fructicola (the stand isolate ICMP 18581) with the accession numbers ON960278 (100%), ON974476 (96%), ON685214 (99%), ON964475 (99%), ON685215 (100%), and ON964477 100%), respectively. Anthracnose disease caused by C. fructicola has previously been reported to affect a range of plant hosts worldwide (Guarnaccia et al. 2017). However, it is still unknown on C. fructicola causing anthracnose in soybean in China. This study firstly reports C. fructicola as the causal agent of anthracnose on soybean in the country, and provides a theoretical basis for the diagnosis and control of this disease.

Technological Aspects of Variation in Process Characteristics and Tool Condition in Grinding Process Diagnostics

The article presents the technological aspects of the diagnostics of grinding processes. The main features of the grinding process and their importance in diagnostic issues are discussed. Selected issues of research and assessment of the condition of the active surface of grinding wheels are presented. The authors pointed out that the parameters used to assess the topography of the ground surfaces do not have sufficient possibilities to differentiate the surface condition of the grinding wheels. This publication draws attention to the possibility of using new dedicated parameters to assess the properties of the grinding wheel surface. These parameters have a high ability to differentiate changes occurring as a result of the abrasion of grain vertices, their chipping or loading of the grinding wheel surface. The methodology of assessing the processes of abrasive grain wear and changes in the shape and dimensions of the grinding wheel, taking into account the probabilistic features of the grinding process, was formulated. The directions for the development of abrasive tools are presented, pointing to hybrid tools with a multi-phase structure, modified by additions of abrasive aggregates. A new research direction has also been formulated on the use of additive technology to produce specialised abrasive tools, including those with built-in process sensors.

Analysis Of Variation Of Paddle Wheel Photovoltaic Wheel Form In Microalgae Cultivation On Electricity Consumption

The main problem that is often found in the failure of microalgae production is poor water quality during the maintenance period. One of the causes of deteriorating water quality is the lack of oxygen which endangers microalgae which can inhibit cell growth so that it can reduce its productivity. On this basis, efforts are needed to refresh the water or aeration to help increase the dissolved oxygen (DO) level in the microalgae growth container using a paddle wheel. The development of an aerator blade design that has optimum efficiency is needed to reduce high electricity consumption and see more effective cell growth. For these problems, in this study, variations of the paddle wheel will be analyzed. Variations in the shape of the wheel used, namely straight and curved with the available aerators, are expected to have an optimum speed, area coverage and increase the amount of dissolved oxygen (DO). The method used is the experimental method . Based on this research, it was found that an increase in the value of cell growth occurred in variations in the shape of a straight paddle wheel of 122 cells/ml .

Towards the understanding of wheel-rail flange squeal: In-situ experiment and genuine 3D profile-enhanced transient modelling

Wheel-rail squeal noise during train turning has been a tricky problem influencing passengers and nearby residents. The tonal curve squeal that mainly occurs at the inner rail has been extensively studied, while the broadband flange squeal that takes place at the outer rail that can be equally annoying is seldom mentioned and hardly investigated. This paper presents a study aiming at understanding the mechanism of wheel-rail flange squeal from phenomenon to the underlying source. The study systematically demonstrates the connection between the observed wheel-rail flange squeal noise and contact force, with measurements taken from a series of well-controlled in-situ experiments on an operating metro line, and numerical simulations. An integrated transient model consisting of three submodels on train dynamics, rail dynamics, and wheel-rail contact incorporating genuine 3D surface irregularities is developed specifically for flange squeal analysis. The developed model can reproduce the characteristics of flange squeal and correlates wheel-rail contact force with the flange squeal noise with satisfactory performance. Features of flange squeal under four-speed levels corresponding to in-situ experiments are reappeared from global dynamics to local contact status. An explanation of the generation mechanism of flange squeal is proposed by measurement observation and confirmed through the proposed model with multiple influencing key factors, including train speed, contact position, shape of contact patch, contact creepages, and wheel and rail irregularities. The present study is expected to establish a footstone for the mechanism comprehension of flange squeal and inspire further research in this area.

Optimisation of wheelset maintenance by using a reduced flange wear wheel profile

This paper investigates whether it is possible to develop a wheel profile design that will extend wheelset life compared to an existing commonly used Great Britain passenger wheel profile, the P8. The P8 wheel profile was originally developed in the late 1960s as an alternative to a 1:20 coned wheel profile (the P1). The P1 often required frequent turning as the conicity could increase quickly over time as the wheel wore in service. The P8 was designed based on an average worn shape of a P1 wheel. The P8 was found to stay closer to its original shape as it wore in service. However, new P8 wheels or newly profiled P8 wheels tend to experience a high initial flange wear rate in the first 20,000–30,000 miles, until the worn wheel shape reaches ‘dimensional stability’; after this, the flange width typically remains relatively constant. A ‘Reduced Flange Wear’ (RFW) wheel profile has been developed, based on the P8 profile but with a modified flange root geometry. The Wheel Profile Damage Model has been used to calculate how the proposed RFW wheel profile could reduce wear rates and therefore increase wheelset life. This paper presents results for a typical electric multiple unit train (EMU1) running on rural and suburban routes and a higher speed variant (EMU2) running on an inter-city route. The effect of the proposed RFW profile on rail rolling contact fatigue (RCF) has also been evaluated using the Whole Life Rail Model, for the same routes. The results suggest that the proposed RFW profile does reduce flange wear compared to a P8, with larger reductions achieved on routes that are more curvaceous. For wheel turning based purely on restoring wheel profile geometry, the RFW profile could half the amount of material removed at each turning (based on turning wheels at 250,000 miles). Furthermore, the results show that the RFW profile experiences slightly less wheel RCF damage than the P8. When new, the RFW profile appears to cause slightly higher rail RCF than a new P8 (For radii 700 m &lt; R &lt; 1300 m); however, the results suggest that worn RFW profiles cause very similar rail RCF to that caused by worn P8 wheels.

A Study of Design and Analysis of Automobile Wheel Rim Using Different Fillet Radius and Different Y Spoke Angle

Abstract: Wheel rims are the most important part of automobile, in an automobile there are fatigue loads and static loads which are actively participated in design. There are several ways of failure of wheel rim like critical stresses and material failure due to design, dimension and shape of wheel also play vital role in its dimensions and shape vehicle rim design. Present paper studied the Y angle optimization in alloy wheel rim. The present design analysed by ANSYS software. For the structural analysis for the remote force the magnitude applied is 1000N and for the pressure which applied on the wheel is 245kPa. Therefore, so comparing the wheels with the total deformation occurred alloy wheels are better than the steel wheel and comparing the both the alloy wheels multi-spoke alloy wheel is better than the 6-spoke alloy wheel. The total deformation of 8 spoke alloy wheel with 55° Y spoke angle, figure clearly depicted the total deformation maximum value 0.00155mm maximum at base of wheel or outer periphery of wheel rim. Keywords: Wheel Rim, Y Spoke Angle of rim, fillet radius of rim, total deformation occurring, ANSYS

Flow-noise characteristics of turbocharger compressors with rotational balance cuttings

To correct the balance of the rotating assembly of a turbocharger, some parts of the compressor wheel are removed by cutting. A numerical investigation of the turbulent flows and flow noises produced by compressor wheels modified with such cutting parts was performed by a turbulence model and detached-eddy simulations. For the 6-cutting case, 0, 2, 4, and 6 circular cuttings and two additional—rectangular and triangular—shapes were used. To investigate the effects of the balance cuttings in a compressor wheel, the evaluation process using computational fluid dynamics was tried. It was found that the fluid forces due to the various wheel shapes have the potential to restore the eccentricity by approximately 50%. Severe variations of velocity, pressure, and turbulent kinetic energy in the interspace between the wheel and volute were observed. In particular, the wavelike patterns of pressure and turbulent kinetic energy were intensified for the modified wheels. The turbulent kinetic energy of the 6-cutting case had a dominant frequency at approximately 3000 Hz. The spectrum of the sound-pressure level of the modified compressor wheels exhibited the features of buzz-saw noise. The flow fields suggested that this feature of the sound pressure is related to the tip-clearance flow affected by the balance cuttings. In addition, the acoustic pressure and flow characteristics of the different types of modified compressor wheels were discussed and the resulting acoustic power was evaluated.

Numerical modeling of material removal mechanism and surface topography for gear profile grinding

Gear profile grinding is more complex than surface grinding owing to the specific shape of the grinding wheel and geometric characteristics of the gear tooth, resulting in difficulties in modeling grinding components. Consequently, conventional grinding models tend to fail. To address this issue, a novel semi-analytical modeling method of the material removal mechanism and surface generation for gear profile grinding is proposed. Firstly, the grinding wheel model is represented by a multi-information fusion matrix that contains kinds of information about grinding grits. Compared with the traditional models that require several matrices to represent respective information, the proposed wheel model incorporates multi-dimensional information without extending the original matrix size and data length, which is more efficient. Then, a numerical model for the grinding process is developed by analyzing grit kinematics and grit-workpiece contact to reveal the material removal mechanism, and it is found that the cross-section shape of 3D cutting chips changes in the direction of the contact line. Furthermore, a surface topography model is established considering the specific pile-up effect. In this process, based on the length conservation of the tooth profile curve after straightening, the body Boolean operation is replaced by matrix calculation which reduces the dimension of data from 3D to 2D. Thus, computing time is reduced greatly, and this method does not require knowledge of the generation mechanism for tooth profile. Finally, experiments are conducted and the effects of grinding parameters on surface topography are investigated. The experimental results match well with model predictions, proving the model is effective. This work provides further understanding of the material removal mechanism for gear profile grinding. Meanwhile, it can also be extended and applied to other grinding processes for workpieces with complex geometry.

Mechanical Wear Contact between the Wheel and Rail on a Turnout with Variable Stiffness

The operation and maintenance of railroad turnouts for rail vehicle traffic moving at speeds from 200 km/h to 350 km/h significantly differ from the processes of track operation without turnouts, curves, and crossings. Intensive wear of the railroad turnout components (switch blade, retaining rods, rails, and cross-brace) occurs. The movement of a rail vehicle on a switch causes high-dynamic impact, including vertical, normal, and lateral forces. This causes intensive rail and wheel wear. This paper presents the wear of rails and of the needle in a railroad turnout on a straight track. Geometrical irregularities of the track and the generation of vertical and normal forces occurring at the point of contact of the wheel with turnout elements are additionally considered in this study. To analyse the causes of rail wear in turnouts, selected technical–operational parameters were assumed, such as the type of rail vehicle, the type of turnout, and the maximum allowable axle load. The wear process of turnout elements (along its length) and wheel wear is presented. An important element, considering the occurrence of large vertical and normal forces affecting wear and tear, was the adoption of variable track stiffness along the switch. This stiffness is assumed according to the results of measurements on the real track. The wear processes were determined by using the work of Kalker and Chudzikiewicz as a basis. This paper presents results from simulation studies of wear and wear coefficients for different speeds. Wear results were compared with nominal rail and wheel shapes. Finally, conclusions from the tests are formulated.

Constructional design of the body shape of large gear wheels

The development of modern machines and means of production is characterized by ever-increasing performance parameters with decreasing equipment weight. When designing large gears, it is also necessary to consider the influence of the body shape of the gear wheel. The body shape of gear wheel must meet the basic requirements of stiffness and strength with the lightest possible construction of the gear wheel body. The work is focused on large gears, made with relief. Such gears can be forged, cast, or made by welding. The shape of the gear wheel body depends on several factors such as the size of the wheel, the material, the method of manufacture or use. The paper provides an overview of the body shapes used by large spur gears. These body shapes of spur gears will be the subject of further research, where suitability will be assessed based on stiffness of teeth and wheel weight.