scholarly journals Influence of Grain Shape in Grinding Wheels on the Machining Quality of Bearing Rings

2022 ◽  
Author(s):  
A. Korotkov
Keyword(s):  
Shape Factor ◽  
Grinding Wheels ◽  
Machining Quality ◽  
Operational Capabilities ◽  
Bearing Factory ◽  
Digital Microscope ◽  
Different Shapes ◽  
Special Computer Program ◽  
Bearing Rings

Abstract. The quality of grinding of bearing races is related to their performance and durability. The aim of this work is to establish how the machining quality of bearing rings depends on the characteristics of grinding wheels, in particular, on such a parameter as the shape of abrasive grains. Several batches of experimental grinding wheels were made, containing grains of different shapes (from isometric to lamellar varieties). Quantitatively, the shape of the grains was estimated by the shape factor parameter (SF), which is equal to the ratio of the diameters of inscribed and circumscribed circles in the contours of the used grains. The shape factor was determined using a scanner or a digital microscope and a special computer program. The tests were carried out on circular, plunge, and finishing grinding, using coolant, on a SIW 4E machine in a bearing factory. The machining quality of the bearing rings was assessed by studying the microstructure, microhardness and roughness of their bearing races. The durability of grinding wheels was determined by the number of machined rings before maximum tool wear. It has been established that by a differentiated approach to the choice of grain shapes in the wheel, it is possible to significantly increase its operational capabilities: increase the microhardness of the ground surfaces, reduce the roughness of processing, and increase the durability of grinding wheels.

scholarly journals Classification of endonasal HHT lesions using digital microscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
F. Haubner ◽  
A. Schneider ◽  
H. Schinke ◽  
M. Bertlich ◽  
B. G. Weiss ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Treatment Modalities ◽  
Hereditary Haemorrhagic Telangiectasia ◽  
Digital Microscopy ◽  
Digital Microscope ◽  
Lower Severity ◽  
Gender Specific Differences ◽  
Vegf Level

Abstract Background Recurrent spontaneous epistaxis is the most common clinical manifestation and the most debilitating symptom in hereditary haemorrhagic telangiectasia (HHT) patients. To this date, there exist only a classification of HHT patients by different genetic mutations. There is no standard classification for the mucocutaneous endonasal manifestations of HHT. The aim of the present study was to document the variety of endonasal HHT lesions using digital microscopy and to propose a clinical classification. Methods We recorded the endonasal HHT lesions of 28 patients using a digital microscope. We reconstructed the 3D images und videos recorded by digital microscope afterwards and classified the endonasal lesions of HHT in two classes: Grade A, presence of only flat telangiectasias in the mucosa level and Grade B, (additional) presence of raised berry or wart-like telangiectasia spots. We investigated also Haemoglobin level by routine laboratory procedures, plasma VEGF level by ELISA, Severity of epistaxis by epistaxis severity score (ESS) and quality of life by a linear visual analogue scale (VAS). Results We found a higher quality of life and a lower severity of epistaxis in Grade A patients in comparison to Grade B patients. No difference in plasma VEGF level and in Haemoglobin between Grad A patients and Grade B patients could be detected. Plasma VEGF levels showed no gender specific differences. It could also not be correlated to the extranasal manifestation. Conclusion The classification for endonasal manifestation of HHT proposed in this study indicates severity of epistaxis und quality of life. Digital microscopy with the ability of 3D reconstruction of images presents a useful tool for such classifications. The classification of endonasal HHT lesions using digital microscopy allows to evaluate the dynamic of HHT lesions in the course of time independent of examiner. This allows also to evaluate the efficacy of the different treatment modalities by dynamic of HHT lesions. Moreover digital microscopy is very beneficial in academic teaching of rare diseases.

scholarly journals Hardened Steels and Their Machining

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 182
Author(s):  
Karel Osička ◽  
Josef Chladil
Keyword(s):  
Cubic Boron Nitride ◽  
Tool Material ◽  
Hardened Steel ◽  
Engineering Industry ◽  
Technical Equipment ◽  
Correct Operation ◽  
Assembly Unit ◽  
The Subject ◽  
Bearing Rings

This article discusses the issue of hardened steel machining. Many components in the engineering industry use hardening as the final heat treatment. These components usually occupy a significant position in a given assembly unit. They guarantee the correct operation of the entire technical equipment in total cooperation with other components. The quality of these components depends on the integrity of their surface. The production of these parts is usually carried out by traditional technological procedures. Clearly, an example of such a technology is grinding. However, this article discusses the application of other finishing technologies using a tool material made of cubic boron nitride (CBN). The technology used is finishing turning with subsequent tumbling technology. The subject of the evaluation is the integrity of the surface. In this part of the experiments, there are mainly individual parameters of surface roughness. Compared components are bearing rings, in this case the inner surface of the housing ring.

Machining quality of high speed helical milling of carbon fiber reinforced plastics

2021 ◽  
pp. 095440622199673
Author(s):  
Adel Abidi ◽  
Sahbi Ben Salem ◽  
Mohamed Athmane Yallese
Keyword(s):  
Surface Roughness ◽  
Carbon Fiber ◽  
High Speed ◽  
Hole Diameter ◽  
Feed Speed ◽  
Carbon Fiber Reinforced Plastics ◽  
Reinforced Plastics ◽  
Machining Quality ◽  
Fiber Reinforced Plastics

Among advanced cutting methods, High Speed Milling (HSM) is often recommended to improve the productivity and to reduce the costs of machining parts. As every cutting process, HSM is characterized by some defects like surface roughness and delamination are the main defects generated in composite materials. The aim of this experimental work is the studying of the machining quality of woven Carbon fiber reinforced plastics (CFRP) using the HSM technology. Experiments were done using different machining parameters combinations to make opened holes in CFRP laminates. This study investigated the effect of cutting speed, orbital feed speed, hole diameter on the delamination defect and surface roughness responses generated in the drilled holes. The design of experimental tests was generated using the approach of Central Composite Design (CCD). The characterization of these responses was treated with the Analysis of variance (ANOVA) and Response surface methodology (RSM). Results showed that the surface roughness is highly affected by the orbital feed speed (F) with contribution of 22.45%. The delamination factor at entry and exit of holes is strongly influenced by the hole diameter D (25.97% and 57.43%) respectively. The developed model equations gave a good correlation between the empirical and predicted results. The optimization of the milling parameters was treated using desirability function to minimize the surface roughness (Ra) and the delamination factor simultaneously.

Effect of copper or carbon fiber addition to the 3D printing of polylactid samples

2020 ◽  
Vol 62 (7) ◽  
pp. 727-732
Author(s):  
L. Zárybnická ◽  
D. Machová ◽  
K. Dvořák
Keyword(s):  
3D Printing ◽  
Fused Deposition Modeling ◽  
Depth Of Field ◽  
3D Print ◽  
Fused Deposition ◽  
Printing Quality ◽  
Digital Microscope ◽  
Effect Of Copper ◽  
The Right

Abstract This paper presents the effect of additives on the quality of a product created by 3D print. The product is created by the most widely used 3D printing method - Fused Deposition Modeling (FDM). Polylactic acid (PLA) filaments are tested without and with the addition of carbon fibers or copper. The specimens are characterized by different methods, such as mechanical testing, measuring roughness by digital microscope with a large depth of field and thermal analysis. In fact, FDM is a problematic process with numerous criterions that affect printing quality. Printing parameters such as print temperature, pad temperature, print speed for 3D printing, printing orientation etc. have an important impact on the performance and quality of FDM components. Due to the correct parameters, the product of the required quality with a longer service life is obtained. The results of testing show that the quantity and choice of the right ingredient has a major impact on the mechanical properties and overall quality of the investigated product.

New Active Online Balancing Method for Grinding Wheel Using Liquid Injection and Free Dripping

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Xining Zhang ◽  
Xu Liu ◽  
Huan Zhao
Keyword(s):  
Grinding Wheel ◽  
Time Varying ◽  
Residual Liquid ◽  
Grinding Wheels ◽  
Abrasive Particles ◽  
Balance Condition ◽  
Liquid Injection ◽  
Grinding Machines ◽  
The Relationship

Grinding is a vital method in machining techniques and an effective way to process materials such as hardened steels and silicon wafers. However, as the running time increases, the unbalance of grinding wheels produce a severe vibration and noise of grinding machines because of the uneven shedding of abrasive particles and the uneven adsorption of coolant, which has a severe and direct impact on the accuracy and quality of parts. Online balancing is an important and necessary technique to reduce the unbalance causing by these factors and adjust the time-varying balance condition of the grinding wheel. A new active online balancing method using liquid injection and free dripping is proposed in this paper. The proposed online balancing method possesses a continuous balancing ability and the problem of losing balancing ability for the active online balancing method using liquid injection is solved effectively because some chambers are full of liquid. The residual liquid contained in the balancing chambers is utilized as a compensation mass for reducing rotor unbalance, where the rotor phase is proposed herein as a target for determining the machine unbalance. A new balancing device with a controllable injection and free dripping structure is successfully designed. The relationship between the mass of liquid in the balancing chamber and the centrifugal force produced by liquid is identified. The performance of the proposed method is verified by the balancing experiments and the results of these experiments show that the vibration of unbalance response is reduced by 87.3% at 2700 r/min.

scholarly journals Quality of screen printing in knit fabric for different mesh count on semi solid design

2020 ◽  
Vol 6 (6) ◽  
Author(s):  
Rasheda Begum Dina ◽  
Md Zulhash Uddin ◽  
UmmulKhair Fatema
Keyword(s):  
Screen Printing ◽  
Visual Assessment ◽  
Color Difference ◽  
Mesh Screen ◽  
Microscope Images ◽  
Different Types ◽  
Digital Microscope ◽  
Semi Solid ◽  
Screen Mesh

In semi solid design, the parameters of the quality of the printed fabric were color fastness, level of print detail, color difference, print coverage, saw-tooth effect, line sharpness etc. Actually, printed fabric quality was evaluated by these parameters. Again, print coverage, saw-tooth effect, line sharpness, etc. were examined by estimating different distances, angles etc. in printed fabric and these factors were compared with image positives. Mesh opening effect on the quality of screen printed fabric was investigated after printing the semi solid design on knit fabric using different mesh count screens and different types of the link. To print semi solid design on knit fabric different types of ink as well as non-identical mesh count was used. Then mesh screen out come on the design and form of printed fabric in screen printing was examined. For the evaluation of semi solid design effect there remains two different methods.The first one is visual assessment and another way is microscope observation. Here, to determine the probability of the amount of ink flowing by the screen, mesh opening area of every screen was considered and it was done from respective digital microscope images.

scholarly journals Operational capability assessment for the hyperspectral sensor NA-GS using statistical and simulation modeling

2019 ◽  
pp. 74-83
Author(s):  
S. A. Zotov ◽  
E. V. Dmitriev ◽  
S. Yu. Shibanov ◽  
V. V. Kozoderov ◽  
S. A. Donskoy
Keyword(s):  
Simulation Modeling ◽  
Experimental Testing ◽  
Space Station ◽  
Quality Criteria ◽  
Statistical Simulation ◽  
Hyperspectral Images ◽  
Scientific Instrument ◽  
Operational Capabilities ◽  
Monitoring And Forecasting

Within the framework of the program on Earth remote sensing from space, the hyperspectral camera NA-GS (scientific instrument "Hyperspectrometer") produced by NPO Lepton (Zelenograd, Moscow) will be installed on the Russian segment of the International Space Station (ISS) for experimental testing of the ground-space system for monitoring and forecasting natural and man-made disasters. The practical use of this system is associated with solving certain problems of thematic processing hyperspectral images that must meet certain quality criteria. In this paper, we propose a technique for determining the operational capabilities of NA-GS instrument based on statistical simulation modeling (SSM) data. The concept of the proposed SSM includes the ability to perform model experiments for a test polygon of complex shape, simulation of hyperspectral imaging of selected parts of the polygon with a specified accuracy, and taking into account the clouds and the zenith angle of the sun. The influence of external observation conditions on the quality of hyperspectral images is considered. Numerical experiments were carried out for selected test areas. The analysis of the results obtained confirms reliability of the proposed technique.

scholarly journals THE EFFECT OF ABRASIVE GRAIN SHAPES ON QUALITY OF FERRITE MAGNETS GRINDING PROCESS

2020 ◽  
Vol 14 (2) ◽  
pp. 117-124
Author(s):  
Bayu Rahmat Saputro ◽  
Amin Suhadi
Keyword(s):  
Chemical Composition ◽  
Single Layer ◽  
Processing Parameters ◽  
Grinding Process ◽  
Model Design ◽  
Grinding Wheels ◽  
Abrasive Grains ◽  
Abrasive Grain ◽  
Shape And Size

Abstract A research was conducted on the grinding process of ferrite magnet with Strontium ferrite type (SrO.6 (Fe2O3)) using electroplated single layer grinding wheels. Many cracks have been found on work pieces during this work, which is coming from grinding processes. Research is conducted starting from chemical composition test and the effect of the shape and size of the abrasive grain of grinding wheels to the quality of grinding process results by measuring crack ratio of the work piece.  In this experiment, 3 (three) model design of grinding wheels with three different size and shape of abrasive grains are made. All of processing parameters are set at the same value as ordinary process.  The experimental results shown that 3rd model have the best results from the outputs number and also the lowest reject crack ratio compared to 1st and 2nd models. This is because the 3rd model has blocky shape which its distribution structure is denser and more uniform compared to the irregular shape, so that continuous grinding on hard and brittle work pieces is more stable and suitable

The temperature of the holes of the bearing rings when grinding with a precast textured wheel

2022 ◽  
Vol 2022 (1) ◽  
pp. 29-36
Author(s):  
Vladimir Gusev
Keyword(s):  
Thermal Stress ◽  
Experimental Models ◽  
Grinding Process ◽  
Grinding Wheels ◽  
Average Temperature ◽  
Bearing Rings ◽  
Grinding Time

The problem of reducing the thermal stress of the grinding process of bearing rings has been viewed. The possibility of reducing the temperature of the treated surface based on the use of precast textured grinding wheels has been presented. Experimental models of pulse, contact, average temperature, velocities and rates of their change in the function of grinding time are found.

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