Evaluation of the Relationship Among Dressing Conditions Using Prismatic Dresser, Dressing Resistance, and Grinding Characteristics

In the grinding process, the grinding wheel surface condition changes depending on the dressing conditions, which affects the ground surface roughness and grinding resistance. Several studies have been reported on the practical application of dressing using prismatic dressers in recent years. However, only a few studies that quantitatively evaluate the effects of differences in dressing conditions using prismatic dresser on the ground surface roughness and grinding resistance have been reported. Thus, this study aims to evaluate quantitatively the effect of the difference in dressing conditions using the prismatic dresser on the ground surface roughness and grinding resistance by focusing on the dressing resistance. In the experiment, dressing is performed by changing the dressing lead and the depth of dressing cut with a prismatic dresser, and the ground surface roughness and grinding resistance are measured. Consequently, by increasing the dressing lead and the depth of dressing cut, the ground surface roughness increased, and the grinding resistance decreased. This phenomenon was caused by the increase in dressing resistance when the dressing lead and the depth of dressing cut were increased, which caused a change in the grinding wheel surface condition. Furthermore, the influence of the difference in dressing conditions using the prismatic dresser on the ground surface roughness and grinding resistance can be quantitatively evaluated by using the dressing resistance.

Effect of Graphene nanoplatelets (GNP) reinforcement on grindability of zirconium diboride ceramics

The grindability of graphene nanoplatelets (GNP) reinforced ZrB2 was studied using resin bonded diamond grinding wheel under dry and wet conditions. A comparative study of grinding forces was performed at selected wheel surface speeds and depth of cuts for surface grinding. ZrB2-GNP showed lower normal grinding forces due to the reduced hardness. The presence of GNP reinforcement in ZrB2 resulted in lower tangential forces and reduced specific grinding energy due to the role of GNP as solid lubricant. The measured forces showed good correlation with the micro cutting model for ZrB2 and ZrB2-GNP under dry condition. The tangential forces showed same trend as normal forces at different depth of cuts and wheel surface speeds for both ZrB2 and ZrB2-GNP with average force ratios of 0.3 and 0.35 respectively. The presence of porosity in ZrB2 increased the normal grinding forces during wet grinding. Scanning Electron Microscope (SEM) images of the grinding chips indicated a mixture of both the ductile mode and the brittle mode of material removal with predominantly brittle fractured chips. Energy Dispersive Spectroscopy (EDS) confirmed the presence of GNPs in ZrB2-GNP grinding chips. The topography of the grinding wheel showed higher wheel loading after the dry grinding than that of wet grinding. The wet grinding resulted in relatively lower surface roughness (Ra values) compared to that of dry grinding.

Analysis of the Impact Factor of Rail Grinding on Their Condition

The Doctoral Thesis “Analysis of the impact of rail grinding on their condition” is developed by Viktors Ivanovs to obtain a Doctoral Degree in Engineering. The scientific supervisor is Assoc. Professor Dr. sc. ing. Pāvels Gavrilovs. In this Doctoral Thesis rail steels are considered according to standards EN 13674-1:2011 and GOST R 51685-2013. Rail steel defects and reasons for their causes are reviewed. The statistics of damaged and heavily damaged rails in the network “Latvijas dzelzceļš” in the period 2011–2019 is studied and analysed in detail. The statistics of rail grinding train operation in “Latvijas dzelzceļš” within the year period 2011–2019 is gathered and analysed. A research of hardness of 60 E1 type rail running surface, of metal chemical composition of the damaged rail with code X 10.1., and structure analysis was performed. Likewise, statistics of wheelset rejection in the network “Latvijas dzelzceļš” in the period 2016–2019 are gathered and analysed, as well as the number of wheel rim defects in the railway of Russian Federation. The main defects of wheelsets are reviewed. The actual wear of wheels and rails in Latvia and the stated wear in the railway of Russia are modelled. Repair profiles of rail head grinding for Latvian rail ways are modelled and their influence on side wear determined due to the rail and wheel surface interaction. Calculations regarding the wheels with flange angle of 66.8° from worn out profile durability coefficient were performed for Latvian railway according to the entry conditions on rail profiles, developed in this dissertation. A rail grinding method was developed. The wheelset repair and wheel grinding economic expenses were calculated. Recommendations for wheel and rail side wear reduction are presented.

On the resonance sound generated in a vehicle cabin moving at low speed due to breaking force

To improve the comfortability in a vehicle cabin, unwanted noise which is recognized as an allophone generated from automobile wheels was experimentally studied to investigate its generation mechanism and to develop its reduction countermeasures. In this experiment, simultaneous measurements of sound pressure and vibrational acceleration of the wheel surface were performed. Then, frequency analysis, vibrational modal analysis and operational transfer path analysis were performed by using measured data. The results show that this kind of noise started in a low frequency first and then became higher. Furthermore, the high-frequency noise was mainly generated by vibrational acceleration at its center and near the rim when the wheel spoke gets close to the brake caliper. The high-frequency noise is around 250Hz, 750Hz, 1000Hz and 1250Hz, and the wheel spoke easily gets vibration and resonance mainly from around 750Hz and 1000Hz. Vibration at 750Hz occurs on the side of the wheel spoke in the rotation direction, while vibration at 1000Hz occurs at the midpoint of the wheel spoke. The closer to the brake caliper, louder noise was generated at the wheel spoke.

Geometrical- and Tooth Contact Analysis of the Areas and Perimeters on the Archimedean Worm Wheels Depending on the Modification of the Axial Module

With the knowledge of the recommendations from reference literatures - six types of Archimedean worm gear drives were designed with the modification of the axial module. After that computer aided models were generated. These pairs were loaded by the same torque to analyse the mechanical parameters on the tooth contact zone. Due to the geometrical establishment, three teeth are connected with the worm surface at the same time, that is why these teeth are analysed. Polygon method was used to approach the kinematical impression on the worm wheel surface. As a result, we were able to define the area- and perimeter percentages of these impressions on the worm wheel surface for each tooth. We also determined the correlation between the axial module and the analysed mechanical parameters supposing average values on the contact surfaces.

Modeling And Simulation of The Advanced Structured Surfaces Machined By Specially Patterned Grinding Wheels Via The Structuring Grinding Process

In this work, the ability to reshape the grinding wheels with special patterns to produce advanced structured surfaces with several geometries is studied. Firstly, a mathematical model is built for the process relating geometries of the grinding wheel, geometries of wheel patterns, the produced structured surface with the grinding operating parameters. Then, different regular and irregular geometries are designed to be patterned over the wheel surface. Afterward, a simulation method to express the patterned wheels and the structured surface at different working conditions is developed. The effects of the pattern geometries on the obtained structured surfaces are investigated.

Development of technological equipment for restoration of rolled wheeled pairs of railway wagons

Introduction. The problem of the shortage of energy-efficient restoration technologies makes it a priority to develop new technological equipment for the restoration of the rolling surfaces of railway wheels using highly concentrated energy sources. Currently, in the practice of repair DPO, discarded non-bonded wheels are increasingly replaced with new ones, but their resource potential is high during the operation. This approach is not technically and economically feasible.Materials and methods. This article presents the results of the strength calculation of the main moments of forces and dynamic loads per wheel pair. The problem of repair equipment related to the lack of the independent mobile complexes that ensure prompt arrival at the work site and high quality restoration of the design geometry of the wheel surface is formulated.Results. To solve this problem, a mobile complex was designed and developed, which allows to restore the design geometry and modify the high physical and mechanical properties of the riding surface with optimal stresses in the phase structure of the wheel base.Discussion and conclusion. It is recommended to use the results of the research carried out for the design, creation and production of high-tech repair equipment.

Simulation to Microtopography Formation of CBN Active Abrasives on a Honing Wheel Surface

The microtopography of a honing wheel surface composed of active abrasive grains is the key factor affecting the honing characteristics, and control of it is a sufficient condition to realize high-efficiency precision honing. Based on the magnetron sputtering method and phase field method, a theoretical model of cubic boron nitride (CBN) coating formation on a honing wheel surface is established. The physical vapor deposition (PVD) discrete phase field equation is solved by the finite difference method. A MATLAB program is compiled to simulate the formation process and micromorphology of the CBN coating on the honing wheel surface. A Taguchi method is designed to study the relationships of the sputtering time, substrate temperature, gas flow rate, and reaction space with the number of active abrasives and the length, width, height, and size of the abrasives. The simulation results are highly similar to the scanning electron microscopy (SEM) examinations, which shows that the model can accurately and effectively simulate the abrasive morphology of the wheel surface under different process conditions and provide a theoretical basis for the prediction and control of the CBN wear morphology on a honing wheel surface.