Grinding Of Glass Research Articles

A Kernel-Based Calibration Algorithm for Chromatic Confocal Line Sensors.

In chromatic confocal line sensors, calibration is usually divided into peak extraction and wavelength calibration. In previous research, the focus was mainly on peak extraction. In this paper, a kernel-based algorithm is proposed to deal with wavelength calibration, which corresponds to the mapping relationship between peaks (i.e., the wavelengths) in image space and profiles in physical space. The primary component of the mapping function is depicted using polynomial basis functions, which are distinguished along various dispersion axes. Considering the unknown distortions resulting from field curvature, sensor fabrication and assembly, and even the inherent complexity of dispersion, a typical kernel trick-based nonparametric function element is introduced here, predicated on the notion that similar processes conducted on the same sensor yield comparable distortions.To ascertain the performance with and without the kernel trick, we carried out wavelength calibration and groove fitting on a standard groove sample processed via glass grinding and with a reference depth of 66.14 μm. The experimental results show that depths calculated by the kernel-based calibration algorithm have higher accuracy and lower uncertainty than those ascertained using the conventional polynomial algorithm. As such, this indicates that the proposed algorithm provides effective improvements.

Comprehensive Review on Research Status and Progress in Precision Grinding and Machining of BK7 Glasses.

BK7 glass, with its outstanding mechanical strength and optical performance, plays a crucial role in many cutting-edge technological fields and has become an indispensable and important material. These fields have extremely high requirements for the surface quality of BK7 glass, and any small defects or losses may affect its optical performance and stability. However, as a hard and brittle material, the processing of BK7 glass is extremely challenging, requiring precise control of machining parameters to avoid material fracture or excessive defects. Therefore, how to obtain the required surface quality with lower cost machining techniques has always been the focus of researchers. This article introduces the properties, application background, machining methods, material removal mechanism, and surface and subsurface damage of optical glass BK7 material. Finally, scientific predictions and prospects are made for future development trends and directions for improvement of BK7 glass machining.

Data analysis and optimization of cutting parameters for CNC rotary grinding of a crystal glass

Data analysis and optimization of cutting parameters for CNC rotary grinding of a crystal glass

Experimental analysis of chemical removal effect in RISA grinding of optical glass

In the large-aperture lens manufacturing, not only high surface quality but also high productivity is required. From this perspective, Reaction-Induced-Slurry-Assisted grinding (RISA grinding), in which cerium oxide slurry is supplied instead of using general grinding fluid, has been developed to achieve high surface quality at high removal rate. However, the surface profile error becomes large due to chemical removal effect of the cerium oxide slurry. Therefore, the purpose of this study is to experimentally investigate the influence of the chemical removal effect on the surface profile error using AE signals and servo current signals in RISA grinding. First, relation between dwell time and removal depth is analyzed by conducting a basic grinding test without the workpiece rotation. The result shows that the actual removal depth increases with increase of dwell time despite applying the constant depth of cut. Then, zero-cut RISA grinding test is conducted. It is found that the removal process proceeds even though zero-cut grinding, and its removal rate varies according to the wheel feed rate. Furthermore, the amount of cerium oxide abrasives adhered to the grinding wheel can be estimated from the AE signals and servo current signals.

ИСЛЕДОВАНИЕ КОМПОЗИЦИОННЫХ МАТЕРИАЛОВ НА ОСНОВЕ АЛЮМОФТОРСИЛИКАТНОГО СТЕКЛА

The results of a comparative analysis of dental glass ionomer cements are compared: "AHfil +" (AHL, United Kingdom), "Ketac Molar Easymix" (3M ESPE, USA), "Fuji IX GP" (GC, Japan), "ProGlass Nine" (Silmet , Israel), "Polyacrylin" (TechnoDent, Russia), "Cemion" (VladMiVa, Russia), "Kemfil" (StomaDent, Russia) and "Glassin Rest" (Omega-Dent, Russia) in terms of working time, hardening time, strength compression, radiopacity, microstructure and chemical composition. It is shown that the main component of the powders of these GICs is crushed calcium ("Kemfil"), strontium ("AHfil +", "Cemion" and "Fuji IX GP"), calcium-strontium ("ProGlass Nine", "Polyacrylin" and "Glassin Rest") and lanthanum-calcium aluminofluorosilicate glass ("Ketac Molar Easymix"). All of them contain phosphorus. Differences in powder granulometric composition indicate a difference in the technology of glass grinding during their production. The working time of the studied GICs is from 1 to 3.5 minutes. The requirements of GOST 31578-2012 and ISO 9917-1:2007 do not correspond to "ProGlass Nine" (36 ± 3 MPa), "Kemfil" (68±6 MPa) and "Glassin Rest" in terms of strength, and "ProGlass Nine" in hardening time. "Fuji IX GP" has the highest strength (201 ± 33 MPa), the rest of the GIC - 142-169 MPa. All studied GICs, with the exception of the non-radiopacity "ProGlass Nine", have a radiopacity corresponding to 1 mm of aluminum. According to the results of the tests, "AHfil +", "Ketac Molar Easymix", "Fuji IX GP", "Polyacrylin" and "Cemion" are recommended for clinical use by dentists

Mechanical Performance of Lean Mortar by Using Waste Glass Powder as a Replacement of Cement

Abstract: In present life, glass is used in construction, soft-drink bottles, medicinal bottles, automobiles, mirrors, windscreen, doors, windows, decorative items, tube lights, bulbs and other electronic gadgets etc. Glass has limited life period, so after completion of its utility period it is either stock piled or sent to landfills without being recycled. The aim of this work was to use the waste glass powder (WGP) as a partial replacement of cement for making mortar and compare its performance with normal cement mortar mix of ratio 1:3. In this research various types of waste coloured glasses and cleared glasses were used for making glass powder. Glass powder was obtained from grinding of waste glass. The main goal of this study is to demonstrate the possibility of using waste glass powder (WGP) as a partial replacement of cement which is used in mortar In this research work cement mortar cubes were used to understand the influence of the waste glass powder (WGP) on the compressive strength. A series of tests were conducted to study the effect of 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35% and 40% replacement of cement by waste glass powder (WGP) on compressive strength test at 7 days and 28 days. Several test such as Consistency test, Initial and Final setting time, and soundness value of cement paste were also determined. And also the particle size effect was evaluated by using glass powder of size 75μm-90μm and glass powder of size less than 75μm. A total of 17 trial mixes were prepared for both sizes of glass powder.

Identification of Tribological Phenomena in Glass Grinding by Acoustic Emission Sensing

Identification of Tribological Phenomena in Glass Grinding by Acoustic Emission Sensing

Morphostructure of garnets from coastal-marine placers
 as a key feature for determining their processing technology

One of the most popular abrasive materials at the
 moment is natural garnet sand. Interest in it increased
 significantly after the collapse of the USSR, as many
 industrially significant geological objects were preserved
 within the borders of the former Soviet republics. Many
 primary deposits of raw garnet materials have been
 explored in Russia, but almost all of them are not of
 industrial interest for economic reasons. Currently, the
 coastal zone of the White Sea is considered prospective
 for the discovery of industrially significant placers and
 placer occurrences of garnet sand. The range of application
 of garnet sand is very wide – it is waterjet cutting,
 cleaning of various surfaces and removal of corrosion
 defects, free grinding of glass and porcelain and
 the production of grinding powders. In 2021, the volume
 of government purchases of garnet sand in physical
 terms increased by 16.3 %, and the volume of commercial
 purchases increased by 64.2 % compared to the same
 period of the previous year. Based on the study of the
 composition of the garnet mineral group, we used a set
 of research methods, including precision (X-ray spectral
 and electron microscopy) in order to determine the
 technology of obtaining industrial concentrates.
 The development of new occurrences of coastal garnet-
 containing sand in the Arkhangelsk region can provide
 the country with highly liquid, strategic raw materials.

Investigations on the micro-interactions of grit-workpiece and forces prediction in ultrasonic vibration side grinding of optical glass

The cutting force in ultrasonic vibration side grinding (UVSG) of brittle materials is of significance for the machined quality. However, the micro-interaction mechanism between abrasive grits and workpiece remains a significant issue in terms of the research on cutting forces in the brittle material grinding due to the stochastic distribution nature of the grits. Meanwhile, these micro-interactions are further affected by ultrasonic vibration in UVSG process. Considering these issues, this paper aims at modeling the cutting force affected by the stochastically distributed grits and ultrasonic vibration to reveal the multi-scale grinding mechanics in UVSG of optical glass. Through modeling the stochastic grinding wheel surface and analyzing the kinematics of multi-grits, the unified motion trajectory and the instantaneous chip thickness in UVSG were enabled to derived to determine the different grit-workpiece interaction stages. With consideration of the ultrasonic vibration effects on the micro-interactions, a novel theoretical cutting force model was developed based on the analysis of force generated at three interaction stages, i.e., rubbing, plowing, and cutting stages. The numerical simulations of this model could provide the time-domain variation features of cutting forces to evaluate the fluctuations and trends of the cutting forces from multi-scales. Experimental verifications indicated that the cutting force and its fluctuations are within the acceptable error margin. Furthermore, a thorough analysis of force fluctuating situations at different ultrasonic vibration amplitudes was conducted. The analytical results indicated that an increase in ultrasonic vibration amplitude was not only beneficial to restrain the force fluctuation, but helpful to reduce the brittle fracture damages of optical glass. The evolution trend of cutting force in different grinding conditions and wheel specifications were discussed in detail to reveal the influence mechanisms of machining parameters on the cutting forces. Afterwards, the detection results of ground workpieces demonstrate that the introduction of ultrasonic vibration would improve the machined quality of optical glass in UVSG process.

Identification of Glass Powders and Sands from the Crushing of Glass Waste from the City of Lomé in Togo

The sustainability of a city depends on the effective and efficient management of its solid waste. Waste recycling channels mainly process glass bottles for direct reuse. Some of these sectors carry out the crushing and grinding of end-of-life glass waste for use in civil engineering without the identification in terms of building materials being clearly established. The present study therefore aims to determine the physical and chemical characteristics of glass powders and sands resulting from the crushing and grinding of glass waste from Grand Lomé in Togo in order to consider their granular potential. Samples of sand and glass powder from the crushing and grinding of white, brown and green glass were subjected to characterization tests in the laboratory followed by analysis of the granular parameters and their modeling by Weibull’s law. The results show that the powder and the glass sand contain a high proportion of silica (SiO2) ranging from 69.11% to 70.18% and a low proportion of alumina (Al2O3) (less than 0.07) and iron (Fe2O3) (lower to 1.09). These three materials have tight and male graded grain sizes (Cu Cc omogeneous (k dab Mf 2.1) make these materials probable aggregates for plaster and coating mortars. Nevertheless, an in-depth study will be made to determine a suitable formula.

COMPARATIVE INVESTIGATION OF GLASS WASTE GRINDING IN VARIOUS MILLS

The present work deals with systematic grinding investigation and determination of grindability of container glass bottles. The systematic grinding tests were carried out in three different kinds of ball mills (a drum mill, a vibrating mill, and a planetary mill) with different energy intensities (low, medium, and high intensity) in dry conditions. In addition, the specific grinding work and specific surface area were determined in every case. The grindability test was performed by the Universal Hardgrove Mill, moreover, the Bond-Work Index was calculated from the Hardgrove Grindability Index. In this research work, the focus was on analysing the grindability of container glass bottles and the goal was energy-efficient milling of glass waste to produce glass foam powder for further utilization (for example glass foam) in a sustainable way. Based on the obtained results, it can be concluded that the optimal milling apparatus for container glass grinding is the drum mill. The reason why is that it has a low specific grinding work (151.52 kWh/t) in comparison with the other two types of mills (3488.37 kWh/t for the planetary mill and 1106.38 kWh/t for the vibrating mill) resulting in a relatively high specific surface area (11314 cm2/g). In the case of grinding industrial quantities of glass waste, the drum mill has a much higher capacity compared to the vibrating mill and the planetary mill.

Subsurface damage evaluation in the single abrasive scratching of BK7 glass by considering coupling effect of strain rate and temperature

BK7 glass has been extensively used in astronomical observation systems, laser fusion devices and precision optical measuring instruments. In order to improve the surface integrity during the high-speed grinding of BK7 glass, the underlying science in the single abrasive scratching of BK7 glass has been theoretically and experimentally explored. It is found that in the abrasive-workpiece contact zone the coupling effect of the strain rate and temperature plays an important role in affecting the material properties, the radius of the plastic deformation zone, the distribution of the elastic stress and the length of the median which in turn affect the subsurface damage in the single abrasive scratching process. The model for predicting the depth of subsurface damage by considering the coupling effect of the strain rate and temperature in the single abrasive scratching of BK7 glass has been theoretically developed and experimentally validated. It is also noted from experimental analysis that with an increase of the strain rate and temperature caused by the high scratching speed at the same cutting depth the radius of plastic deformation zone decreases, and the initiation and propagation of the median crack, lateral crack and radial crack are suppressed, which facilitate for shortening the crack length, reducing the brittle fracture, improving the surface integrity and decreasing the subsurface damage.

Wheel wear-related instability in grinding of quartz glass

Grinding is a popular method for producing high-quality parts made of hard and brittle materials. A lot of researchers have focused on the impact of grinding parameters on surface quality. However, only a few studies discussed the surface quality instability caused by the grinding wheel wear during a long grinding process. In this paper, through wheel state monitoring and surface quality testing of ground samples, it is found that the relationship between ground surface roughness and theoretical undeformed chip thickness is significantly affected by the grinding wheel wear state rather than maintain steady as described in most available models. By introducing the normal grinding force, a linear relationship was found among normal grinding force, undeformed chip thickness, and ground surface roughness. Besides, sensitivity analysis was conducted to guide the parameter adjustment to maintain the stability of ground surface roughness and grinding state. The mechanism of the effect of wheel wear on normal grinding force was also studied in detail. This study will help to further understand the mechanism of the influence of wheel wear on the grinding stability.

Crack Forms Sensitivity-Based Prediction on Subsurface Cracks Depth in Ultrasonic-Vibration-Assisted Grinding of Optical Glasses

Subsurface cracks in ultrasonic-vibration-assisted grinding (UVAG) of optical glasses often exhibit diverse forms and proportions. Due to the variety of loads involved in crack formation and propagation, the crack forms and propagation depths have different sensitivities to each process parameter. Predicting the maximum subsurface cracks depth (MSSCD) by considering the varying effects of process parameters plays a key role in implementing effective control of the UVAG process. In this work, the subsurface crack forms and their proportions are investigated by conducting 40 sets of UVAG experiments. The varying effects of the grinding and ultrasonic parameters on the crack form proportions are unveiled by using grey relational analysis. The weighted least square support vector machine (WLS-SVM) prediction model for the MSSCD was developed. Twelve sets of UVAG experiments were carried out to validate the proposed model. The results show that arc-shaped cracks and bifurcated cracks account for 72.5% of all cracks, while ultrasonic vibration amplitude influences most of the proportions of arc-shaped and bifurcated cracks. Compared to other widely used prediction methods, the maximum and average relative prediction errors of the proposed model are 10.54% and 5.59%, respectively, which proves the high prediction accuracy of the model.

Grinding performance evaluation of 3D-printed porous metal-bonded grinding wheel in BK7 glass grinding

Grinding performance evaluation of 3D-printed porous metal-bonded grinding wheel in BK7 glass grinding

Finite Element Analysis of Subsurface Damage of Optical Glass after Grinding

The interaction between abrasive particles and optical element surface can result in various forms of subsurface damage while removing the material. In order to obtain the stress distribution during optical glass grinding, the finite element analysis of optical glass grinding is carried out by using ANSYS software. The stress distribution of optical glass was obtained by establishing the grinding model of consolidated abrasive and free abrasive. The simulation results show that different abrasives have different damage degrees to the glass surface, which provides a useful reference for improving the quality of optical material processing technology.

Selective grinding of glass to remove resin for silicon-based photovoltaic panel recycling

Secondary grinding was investigated as a mean of liberating glass from locked particles of glass and resin obtained by the primary shredding from the silicon-based PV panels. Many previous studies on separating glass from resin have focused on chemical processes. However, a simple physical process—using an eccentric stirring mill to selectively grind the glass, separating the glass from the resin, and concentrating the glass into a narrower particle size group—resulted in successful liberation. Grinding rate analysis using the population balance model quantitatively confirmed that glass particles were more easily ground than resin particles and that locked particles were more easily ground than free particles. This is because the high specific gravity of the glass particles and the greater adhesiveness of the locked particles cause them to be located near the stirring blade of the mill. The selectivity of grinding became more significant and the grinding time shorter as the rotation speed increased. At the optimal grinding speed of 2500 rpm, 97% of the glass was concentrated into particles under 5.6 mm in size in 5 min. The resulting glass particles had a carbon content of 1% or less, which makes them suitable for the manufacture of glass fiber.

Grinding performance and wear of metal bond super-abrasive tools in grinding of Zr-based bulk metallic glass

Bulk metallic glass (BMG) is the new class of promising materials with exceptional mechanical properties and corrosion resistance. BMG parts need grinding to obtain high dimension precision and surface finish. In present research work, Zr-BMG was ground by mono-layer metal bond super-abrasive grinding tools with different abrasive (diamond, CBN) and bond (Ni electroplated, NiCr and Cu-Sn-Ti brazed). The grinding force, surface roughness, surface crystallization status, wear of tools in grinding of BMG with different tools were examined and compared. The specific grinding energy of Zr-BMG was also compared with SS304 steel. The results showed that diamond tool produces lower grinding forces than that of CBN. Ni electroplated tools own lower grinding force than that of brazed ones. Zr based BMG produce higher grinding force and specific grinding energy than SS304 steel. Ni electroplated tools obtain lower surface roughness of Zr-BMG than that of brazed ones. A severe adhesion of Zr-BMG dominates the wear of super-abrasive grinding tools. Ni-electroplated tools produce less adhesion than the brazed tools.

Manufacturing‐induced surface contaminations

SummaryIn the course of classical optics manufacturing glass components are in permanent direct contact with aqueous operating materials. Such contact leads to a certain absorption of water and hydrogenous compounds that may induce severe glass defects. In this contribution, absorption of hydrogen and other contaminants during grinding of glass was observed and qualitatively detected via laser‐induced breakdown spectroscopy. It is shown that hydrogen, calcium, magnesium, and carbon are implanted into the glass surface where the contaminant concentration increases over grinding time or contact time of the glass surface with water and the grinding tool, respectively. The contaminants hydrogen, calcium, and magnesium can be attributed to the water used as lubricant. In contrast, carbon most likely originates from wear debris of the used silicon carbide grinding pads. Several possible mechanisms that lead to such surface contamination of glasses during grinding – diffusion, accumulation in micro cracks as well as the formation of hydrated silica – are finally introduced.

Clinical Analysis of Acute Lung Injury in 26 Cases of Diffuse Large B-Cell Lymphoma Treated with Rituximab Chemotherapy

To summarize and analyze the clinical characteristics, treatment and prognosis of acute lung injury in patients with diffuse large B-cell lymphoma (DLBCL) after chemotherapy with rituximab chemotherapy, so as to improve the understanding of the disease and guide the clinical treatment. Twenty-Six patients with DLBCL were treated with rituximab chemotherapy and developed to acute lung injury in Third Hospital of Peking University from January 2013 to September 2018 were selected. The clinical features, imaging findings, chemotherapy course, therapeutic effect and prognosis were analyzed. The main clinical symptoms of patients were fever, cough and chest tightness, among which 12 patients showed hypoxia and 3 patients showed respiratory failure type I. The mainly manifested chest CT was diffusive glass grinding in both lungs, and some patients were complicated with a small amount of pleural effusion. The onset chemotherapy time was mainly distributed in 2 to 4 courses, the time between the onset of symptoms and the infusion of rituximab was 8 to 49 days. 25 patients shows no obvious limitation in daily life after effective treatment, and 1 patient died of ineffective treatment. There are no typical clinical symptoms in the early stage of acute lung injury after rituximab chemotherapy in DLBCL. Early detection and early hormone therapy are very important to achieve good therapeutic effect.