Wheel Shape Research Articles

Use of magnetic flux techniques to detect wheel tread damage

Rail vehicle wheelsets are regularly maintained to ensure their safe operation on track and prolong their life. This is achieved through measurements to inspect roundness, profile shape, rim thickness and visual inspections of surface damage. If necessary, wheels are re-profiled on a lathe to preserve the optimal wheel shape and remove any visible surface damage. Surface damage is difficult to classify visually, leading to highly subjective results. It is also not possible to establish defect depth through visual inspections. Magnetic flux leakage (MFL) technology has been successfully applied to the detection of defects in rails. This technology has been adapted for the evaluation of wheel damage, resulting in a fast and repeatable method of quantifying damage to railway wheels. This paper describes the theory behind the MFL technique and how it has been applied to the detection of wheel damage. This includes a summary of the assessment of the depth of damage into the wheel tread for a range of wheelsets. The benefits to train operators of adopting this technology are also presented.

3호선 실제선로 조건에서의 레일경좌 변화에 따른 철도차량 주행안전성 해석

It is very hard to analyze the train derailment safety quantitatively at the curved section because of the diversified affect parameters including the complex interaction between wheel and rail, the train conditions such as the shape of wheel, suspension system, the track conditions such as the radius of curve, cant, transition curve, and the operation conditions, etc. Two major factors related to the running safety of railway vehicle are classified as the railway vehicle and the track condition. In this study, when the railway vehicle passing through curves of actual track condition of subway line NO.3 in seoul (<TEX>$Yeonsinnae{\leftrightarrow}Gupabal$</TEX>), the effect that has influence on running safety depending on rail inclination. The analysis result of 1/40 rail inclination condition is more favorable on running safety than other rail inclination conditions because derailment coefficient and wheel unloading ratio are the lowest.

DETERMINATION OF STEERING WHEEL ANGLES DURING CAR ALIGNMENT BY IMAGE ANALYSIS METHODS

Abstract. Optical systems for automatic visual inspections are of increasing importance in the field of automation in the industrial domain. A new application is the determination of steering wheel angles during wheel track setting of the final inspection of car manufacturing. The camera has to be positioned outside the car to avoid interruptions of the processes and therefore, oblique images of the steering wheel must be acquired. Three different approaches of computer vision are considered in this paper, i.e. a 2D shape-based matching (by means of a plane to plane rectification of the oblique images and detection of a shape model with a particular rotation), a 3D shape-based matching approach (by means of a series of different perspectives of the spatial shape of the steering wheel derived from a CAD design model) and a point-to-point matching (by means of the extraction of significant elements (e.g. multifunctional buttons) of a steering wheel and a pairwise connection of these points to straight lines). The HALCON system (HALCON, 2016) was used for all software developments and necessary adaptions. As reference a mechanical balance with an accuracy of 0.1° was used. The quality assessment was based on two different approaches, a laboratory test and a test during production process. In the laboratory a standard deviation of ±0.035° (2D shape-based matching), ±0.12° (3D approach) and ±0.029° (point-to-point matching) could be obtained. The field test of 291 measurements (27 cars with varying poses and angles of the steering wheel) results in a detection rate of 100% and ±0.48° (2D matching) and ±0.24° (point-to-point matching). Both methods also fulfil the request of real time processing (three measurements per second).

DETERMINATION OF STEERING WHEEL ANGLES DURING CAR ALIGNMENT BY IMAGE ANALYSIS METHODS

Optical systems for automatic visual inspections are of increasing importance in the field of automation in the industrial domain. A new application is the determination of steering wheel angles during wheel track setting of the final inspection of car manufacturing. The camera has to be positioned outside the car to avoid interruptions of the processes and therefore, oblique images of the steering wheel must be acquired. Three different approaches of computer vision are considered in this paper, i.e. a 2D shape-based matching (by means of a plane to plane rectification of the oblique images and detection of a shape model with a particular rotation), a 3D shape-based matching approach (by means of a series of different perspectives of the spatial shape of the steering wheel derived from a CAD design model) and a point-to-point matching (by means of the extraction of significant elements (e.g. multifunctional buttons) of a steering wheel and a pairwise connection of these points to straight lines). The HALCON system (HALCON, 2016) was used for all software developments and necessary adaptions. As reference a mechanical balance with an accuracy of 0.1° was used. The quality assessment was based on two different approaches, a laboratory test and a test during production process. In the laboratory a standard deviation of ±0.035° (2D shape-based matching), ±0.12° (3D approach) and ±0.029° (point-to-point matching) could be obtained. The field test of 291 measurements (27 cars with varying poses and angles of the steering wheel) results in a detection rate of 100% and ±0.48° (2D matching) and ±0.24° (point-to-point matching). Both methods also fulfil the request of real time processing (three measurements per second).

A relativistic trolley paradox

We present an apparent paradox within the special theory of relativity, involving a trolley with relativistic velocity and its rolling wheels. Two solutions are given, both making clear the physical reality of the Lorentz contraction, and that the distance on the rails between each time a specific point on the rim touches the rail is not equal to 2πR, where R is the radius of the wheel, but 2πR/1−R2Ω2/c2, where Ω is the angular velocity of the wheels. In one solution, the wheel radius is constant as the velocity of the trolley increases, and in the other the wheels contract in the radial direction. We also explain two surprising facts. First that the shape of a rolling wheel is elliptical in spite of the fact that the upper part of the wheel moves faster than the lower part, and thus is more Lorentz contracted, and second that a Lorentz contracted wheel with relativistic velocity rolls out a larger distance between two successive touches of a point of the wheel on the rails than the length of a circle with the same radius as the wheels.

小型移動ロボットの切り掛け車輪形状に関する検討

小型移動ロボットの切り掛け車輪形状に関する検討

Imaging features and diagnosis of hepatic cystic echinococcosis

Objective To summarize the features of computed tomography (CT) and magnetic resonance imaging (MRI) of hepatic cystic echinococcosis, and investigate the key points of identification and diagnosis. Methods The clinical data of 58 patients with hepatic cystic echinococcosis who were admitted to the Affiliated Hospital of Inner Mongolia Medical University from August 2011 to August 2014 were retrospectively analyzed. Patients received plain and enhanced scan of CT and MRI. Hepatic cystic echinococcosis was divided into the 5 types according to the literatures, including unilocular echinococcasis in type Ⅰ, multivesicular hydatid cysts in type Ⅱ, anechoic content with detachment of laminated membrane from the cyst wall in type Ⅲ, calcification of lesions in type Ⅳ and mixed echinococcosis in type Ⅴ. Patients who were diagnosed as with definite or suspected hepatic cystic echinococcosis underwent surgery. The follow-up including observing the recurrence of hepatic cystic echinococcosis was performed by outpatient examination and telephone interview at postoperative month 3, 6, 12 for 1 year and then once every year up to August 2015, and was ended if there was no recurrence for more than 5 years. Results (1) The results of CT and MRI examinations: of the 58 patients, 54 received scan of CT and 21 received scan of MRI. Seventeen patients were detected in type I with clear-boundary and low-density cystic lesions by CT examination; MRI examinations showed there were single or multiple, round or oval abnormal signal including low T1WI signal, high T2WI signal and low T1WI and T2WI signal of cyst wall. Thirteen patients were detected in type Ⅱ, CT examination showed the daughter cysts of multiple sizes were found in the mother cyst, arranged in honeycomb or wheel shape; MRI examination showed there were lower T1WI signal in the daughter cyst and higher T2WI signal in the daughter cyst compared with signal in the mother cyst, and low signal in the cyst wall of the daughter cyst and mother cyst. Six patients were detected in type III with in sign and water snake sign by CT examination and ribbon sign by MRI examination. Thirteen patients were detected in type Ⅳ, CT examination showed there were irregular high-density calcified shadow with the performances for return or sample volume skins changes. Nine patients in type Ⅴ had more than 2 kinds of lesions. (2) Diagnosis: 4 patients were misdiagnosed by CT examination including 3 with preoperative diagnosis of hepatic cyst and 1 with preoperative diagnosis of metastatic carcinoma of liver, with an accurate rate of diagnosis of 92.6%(50/54). Two patients with preoperative diagnosis of hepatic cystic adenocarcinoma were misdiagnosed by MRI examination, with an accurate rate of diagnosis of 90.5%(19/21). (3) Treatment and follow-up: 58 patients underwent surgery, including 40 undergoing internal capsule removal with external capsule suturing (31 with open operation and 9 with laparoscopic operation), 10 undergoing partial hepatectomy and 8 undergoing external capsule enucleation. Of 58 patients, 3 were complicated with effusion of residual cavity, 2 with unclosed external capsule, 1 with bile leakage and then was cured after 4-8 week drainage. Fifty patients were followed up for 12.0-48.0 months with a median time of 27.1 months and a follow-up rate of 86.2%(50/58). During the follow-up, 1 patient undergoing internal capsule removal had recurrence at postoperative month 8 and was cured by CT-guided interventional therapy using absolute alcohol, and other patients had no recurrence. Conclusions There was a higher accuracy in CT and MRI examinations for hepatic cystic echinococcosis. Honeycomb and wheel shapes are characteristic findings of hepatic cystic echinococcosis in type II. The characteristic performances of CT examination for hepatic cystic echinococcosis in type III are in capsule and water snake signs, and characteristic performances of MRI examination is ribbon sign. The ring-like enhancement of edge by MRI examination is an essential of identification and diagnosis between hepatic cystic echinococcosis and hepatic cyst, and irregular calcification is a differential point between hepatic echinococcosis and hepatic tumor. Key words: Echinococcosis, hepatic; Tomography, X-ray computed; Magnetic resonance imaging; Diagnosis

An investigation on high-efficiency profile grinding of directional solidified nickel-based superalloys DZ125 with electroplated CBN wheel

Profile grinding is an established technology for manufacturing aircraft engine components with a high surface quality and a high dimensional accuracy, for instance, the dovetails of gas turbine blades. In spite of recent advantages, the employment of profile grinding has been impeded by drastic wheel wear and thermal damage, especially when machining difficult-to-cut materials such as titanium and nickel alloys. In this study, grinding experiments with directional solidified nickel-based superalloy DZ125 were performed with the aim to enhance the wheel shape retention, suppress thermal damage, and increase the material removal rate. Instead of conventional abrasive wheels, a monolayer electroplated cubic boron nitride (CBN) profile wheel was employed, and the measurement results showed that the dimensional deviation of the machined surface profile was within tolerance. An analysis of the specific grinding energy revealed that a low specific grinding energy can be achieved by effectively controlling the maximum chip thickness. Only a slight variation of the grinding temperature was measured in the grinding zone between different points along the profile when using a profile-adapted needle nozzle. For the grinding parameters used in this study, a high shape accuracy and a good surface integrity was obtained even at a specific material removal rate of 50 mm3/mm s and grinding in a single pass.

CFD modeling and simulation of a hydropower system in generating clean electricity from water flow

In this study, electric generation capacity of a hydropower system was evaluated through computational fluid dynamics (CFD) modeling and simulation. Performance of paddle wheels in producing hydropower out of running water under different speeds was evaluated, and effects of side and bottom fins and paddle wheel shape on power generation were discussed based on the CFD results. It was also found that, compared to the regular straight paddles, the curved paddles can increase the electricity generation capacity of the entire system by 10–20 % at different water speeds. A preliminary economic analysis revealed the great prospects of applying the presented hydropower technology in regions with rich water resource to produce and supply low-cost, clean, and renewable electricity for a large amount of households and industries.

행성탐사 로버 휠 테스트 베드 설계 및 주행 실험

In this paper, the consideration factors that affect the actual driving of a rover wheel was examined based on the wheel-terrain model. For the evaluation of driving performance in a real environment, the test bed of the rover wheel consists of the driving part of the wheel and sensing part of the various parameters was designed and assembled. Using the test bed, the preliminary driving experiment concerning the slip ratio, sinkage, and friction force according to the rotational velocity and the shape of the wheel were carried out and evaluated. The wheel test bed and the experiment results are expected to contribute to finding the optimal result in the designing of the wheel shape and the planning of the driving conditions through further study.

Modeling vibrations of manual grinding machine ИП2014П

Mathematical models of the manual grinding machine (MGM) ИП2014П were given and their analysis in idling and working stroke conditions was performed. An adequacy of the presented mathemati­cal models with the real modeling object was achieved. The results of the analysis of existing standard requirements to unbalanced masses of abrasive wheels based on the compliance with requirements to local vibrations, affecting the operator were provided. By modeling vibrations on the left handle of the MGM in the idling conditions, it was found that the wheel imbalance is equal to 0.004 mкр on its radius, i. e., at its maximum permissible value according to GOST 23182-78 does not guarantee fulfilling sanitary standards. An assessment of the vibration safety of the MGM in idling and working stroke conditions with abrasive wheels made using tradi­tional shaping technology was carried out. It was found that with the existing ПП 150х25х32 wheel shaping technology, maximum error of the wheel shape and placing it on the spindle of the MGM lead to the vibration excitation on the left handle of the MGM in the idling conditions in the range of (33÷49) mm/s, and (26÷56) mm/s in the working stroke conditions, which is on average 1.6 times higher than sanitary standards.

Simulation of powder flow in a lab-scale tablet press feed frame: Effects of design and operating parameters on measures of tablet quality

The feed frame of a pharmaceutical tablet press is an important process component critical in defining both the total tablet mass and the amount of the active pharmaceutical ingredient (API) within the tablets. In addition to these quantities, the mechanical agitation of the feeder can cause attrition or over-lubrication of the powder blend or granulation flowing through the device. In order to better understand these effects, the discrete element method is used to model powder flow in a single paddle wheel feed frame of a laboratory-scale tablet press with varying particle, process, and equipment parameters. Results show that widely varying particle flow patterns and residence time distributions are achieved for varying paddle wheel shape, rotation direction, and rotation speed. Faster paddle wheel speeds generally lead to more uniform tablet masses whereas slower paddle wheel speeds perform less work on the particles (a surrogate for attrition) and move the particles a smaller distance (a surrogate for the extent of lubrication) in the feed frame before they enter a die and are compressed into a tablet. Finally, the effects of paddle wheel design and powder cohesion are also described.

Verification of simulation of surface texturing on planar surface by grinding

Surface texturing is a means of pattern generation on a workpiece surface to provide functionality or for aesthetic reasons. Grinding is one of the various technology used for surface texturing. Compared with other methods (such as lasers, abrasive jet machining, mechanical cutting or rolling, and etching), grinding has some advantages for large-area texturing. In texturing by grinding, the grinding wheel needs particular shapes such as helical grooves on the peripheral surface of the wheel, depending on the shape of patterns to be generated on a workpiece. A grinding wheel with a helical groove generates patterns on the workpiece by the relative motion of the wheel and the workpiece. The pattern shapes are determined according to the combination of the grinding wheel speed and feed rate, as well as the geometry of the helical groove of the wheel. Before texturing, it is important to predict the textured patterns with a mathematical model. If the textured patterns are predictable, the shape of the grinding wheel and the grinding parameters can be determined. This paper proposes a mathematical model for the prediction of pattern generation, and verification of texturedpatterns based on the simulation resultsis given.

Bread Mould Potmarks from a Protodynastic and Early Dynastic Site in the Nile Delta, Egypt

This article focuses on potmarks from the Western, Eastern and Central Koms of the Tell el-Farkha site. They date back to the Protodynastic and Early Dynastic periods (up until the 1st Dynasty) and are associated with Phases 4 and 5 of the settlement. 91 of the potmarks have been identified and analysed. They were all incised on wet clay and covered either the inside or outside walls of bread moulds. 16 categories of patterns have been distinguished: cross, criss-cross, vertical and horizontal line combination, horizontal line, vertical line, curvilinear line, rectangular-like shape, animal-like shape, plant-like shape, star-like shape, arch-like shape, radial wheel shape, strokes on the rim, V-shaped sign, circle and semi-circle.

Simulation of micro-patterns engraved by grinding process with screw shaped wheel

Grinding is an important means of realizing precision and ultra-precision machining of workpiece surface. The surface patterning of workpiece directly affects its mechanical properties such as friction, wear, contact stiffness, fitting property. Therefore, prediction of the geometry of the workpiece surface is very important to evaluate the workpiece quality to perform mechanical function accurately. In this paper using MATLAB simulation, prediction for the geometry pattern of the workpiece according to the developed shape of the grinding wheel dressed by thread cutting was studied. The model for the geometry of the grinding wheel surface was first developed and subsequently, a new simulation model for surface pattern by grinding process was established. The simulation results could be used to optimize the grinding process and to improve the workpiece surface quality or predict the surface pattern by given grinding parameters.

Constant Depth Scoring of Fibre Reinforced Plastic Structures to Prevent Delamination

Scoring of the outer layers of a workpiece with small engagement (ae) using circular saws is a well known method to avoid unwanted delamination of these layers, such as coatings of wooden particle boards. In edge milling fibre reinforced plastics (FRP), delamination also occurs in the top or bottom layer of the component and requires time intensive rework or scrapping of material. A combined process of scoring and milling is presented in this paper as a means to avoid delamination during machining of FRP structures such as aircraft carbon FRP parts. For the scoring process a diamond electroplated circular wheel is used. To guarantee a constant width of the scored slot, a constant depth of engagement is needed due to the shape of the grinding wheel. Therefore the profile of the scoring path on the workpiece surface is measured with respect to the machine coordinate system to correct a variation in the workpiece thickness and to compensate for uneven clamping. Next, the workpiece is scored with constant depth of engagement (ae,s < 0.5mm) and a high feed velocity of up to 16 m/min. Subsequently, the scored component is machined with a conventional polycrystalline diamond (PCD) milling tool. From experiments it is proven that a delamination-free edge is achievable even with a worn tool (cutting edge radius rn > 50μm) at an increased feed velocity (vf,m = 4.5 m/min). Without scoring, flawed workpiece edges have been obtained with cutting edge radii beyond rn > 23μm (progressive uniform wear stage) and a feed velocity of vf,m = 1.5 m/min. Hence, high performance cutting (HPC) edge milling of composites may be realized by an initial scoring step to fulfil quality requirements of the machined edges and simultaneously increase the tool life of the milling tool.

On the Influence of Wheel Shape upon the Drag Coefficient of a Road Vehicle

On the Influence of Wheel Shape upon the Drag Coefficient of a Road Vehicle

굴삭기휠의 형상별 구조 강도에 대한 내구성 연구

굴삭기휠의 형상별 구조 강도에 대한 내구성 연구

Finite Element Simulation as a Tool to Evaluate Gear Quality after Gear Rolling

Gear rolling is a manufacturing technique for gears with many advantages like reduced material consumption, reduced scrap generation, fast cycle times, good surface quality and improved final properties of the gear wheels compared to conventional production technology based on machining. In order to make use of all these advantages it is desired to reach the final shape of the gear wheel already after rolling. This means that post treatments like grinding should be avoided. This puts high requirements on the shape accuracy after gear rolling. In this paper it was studied if finite element simulation could be used to evaluate the shape accuracy after gear rolling. The measurement of shape accuracy of gear wheels is specified in standards like ISO1328-1. The allowed deviations from nominal shape are often of the order of 10-30 μm for very good qualities. So if such evaluation shall be possible from a finite element simulation the accuracy must be of the same order. In order to have sufficient accuracy of the finite element simulation 2D simulations were performed on a spur gear. The FE code DEFORM was utilized. The shape accuracy was evaluated for gear rolling of two cases. One case had gears with the module of 1 mm. The other case involved gears with a significantly larger module of 4 mm. This was an interesting case since it is known that it is more difficult to roll the gear with good accuracy in large modules.

Brownian ratchet in a thermal bath driven by Coulomb friction.

The rectification of unbiased fluctuations, also known as the ratchet effect, is normally obtained under statistical nonequilibrium conditions. Here we propose a new ratchet mechanism where a thermal bath solicits the random rotation of an asymmetric wheel, which is also subject to Coulomb friction due to solid-on-solid contacts. Numerical simulations and analytical calculations demonstrate a net drift induced by friction. If the thermal bath is replaced by a granular gas, the well-known granular ratchet effect also intervenes, becoming dominant at high collision rates. For our chosen wheel shape the granular effect acts in the opposite direction with respect to the friction-induced torque, resulting in the inversion of the ratchet direction as the collision rate increases. We have realized a new granular ratchet experiment where both these ratchet effects are observed, as well as the predicted inversion at their crossover. Our discovery paves the way to the realization of micro and submicrometer Brownian motors in an equilibrium fluid, based purely upon nanofriction.