Glass Edge Research Articles

Development of a diamond scribing wheel with unequal-pitch micro-penetration teeth

ABSTRACT A “diamond scribing wheel with symmetrical micro-penetration teeth with unequal-pitch design” is proposed for glass cleaving under a low-stress regime in this study. The teeth train is symmetrical in lineup and generated by grinding using a self-developed symmetrical high-speed grinding system that efficiently and effectively produces teeth in half the time of a single teeth grinding system. The diamond scribing wheel created was subjected to a glass scribing test on a grinding system. The breaking stress at glass’s edge was only half that of the equal-pitch design. The experiments also proved that favorable short radial cracks and deep median cracks were created with an 80° cone angle, 2° pitch angle and 10 N penetration force. The depth of median cracks was created by the penetration force of teeth and stress concentration. The resultant glass edges after cleaving were smooth with no evident wrinkles. This technology has great commercial potential.

Monocular Depth Estimation for Glass Walls with Context: A New Dataset and Method.

Traditional monocular depth estimation assumes that all objects are reliably visible in the RGB color domain. However, this is not always the case as more and more buildings are decorated with transparent glass walls. This problem has not been explored due to the difficulties in annotating the depth levels of glass walls, as commercial depth sensors cannot provide correct feedbacks on transparent objects. Furthermore, estimating depths from transparent glass walls requires the aids of surrounding context, which has not been considered in prior works. To cope with this problem, we introduce the first Glass Walls Depth Dataset (GW-Depth dataset). We annotate the depth levels of transparent glass walls by propagating the context depth values within neighboring flat areas, and the glass segmentation mask and instance level line segments of glass edges are also provided. On the other hand, a tailored monocular depth estimation method is proposed to fully activate the glass wall contextual understanding. First, we propose to exploit the glass structure context by incorporating the structural prior knowledge embedded in glass boundary line segment detections. Furthermore, to make our method adaptive to scenes without structure context where the glass boundary is either absent in the image or too narrow to be recognized, we propose to derive a reflection context by utilizing the depth reliable points sampled according to the variance between two depth estimations from different resolutions. High-resolution depth is thus estimated by the weighted summation of depths by those reliable points. Extensive experiments are conducted to evaluate the effectiveness of the proposed dual context design. Superior performances of our method is also demonstrated by comparing with state-of-the-art methods. We present the first feasible solution for monocular depth estimation in the presence of glass walls, which can be widely adopted in autonomous navigation.

Heterogeneous metallic glass composites with a unique combination of strength, plasticity and conductivity

Metallic glass-reinforced Cu-based composites offer a promising avenue for overcoming the trade-off between high strength and high electrical conductivity in materials. In this investigation, heterogeneous CuZrAl metallic glass-reinforced CuCrZr alloy composites are prepared through spark plasma sintering and a one-step hot pressing. The microstructural evolution of the composites during the preparation process and its correlation with mechanical and electrical properties are revealed. Grain refinement and dislocation accumulation in the CuCrZr alloy matrix resulted in strength gain and a trade-off in electrical conductivity. However, precipitation of the Cr-rich phase compensates for the loss of conductivity. Directional strengthening and toughening of the composites are achieved by inducing deformation of the CuZrAl metallic glass reinforcement in the undercooled liquid region to attain its ordered arrangement. Furthermore, the electrical and mechanical properties of the crystalline phase Cu10Zr7 at the edge of metallic glass are predicted and investigated using first-principles calculations, with a focus on its impact on the performance of composites. A novel Cu-based metallic glass composites fabricated using an efficient processing approach offers valuable insights into material selection for electrical conductor applications.

Effect of 3d-transition metal ions on the structural, optical and magnetic properties of chromium-bearing barium borate glass

This article reports the effect of 3d-transition metal ions on the optical features of chromium ions bearing glass host. Interestingly, this study unveiled the charge transfer of Cr ions at high energy (at 347 nm), which is often hidden in earlier reports due to its vicinity to the glass edge, and its immersion in the lattice band of the glass host. In addition to the well-defined charge transfer at low energy (at 378 nm). In this vein, glass composition [(TM)1−(B2O3)80−(BaO)18.7−(Cr2O3)0.3], where TM is the transition metal ions in their oxide form, was prepared via the melt-quenching method at about 1100 °C. X-ray diffraction patterns confirmed the amorphous structure of the glass, and the chemical composition was examined using energy-dispersive X-ray spectra. The decrease in density (from 2.74 gcm−3 to 2.59 gcm−3) and the increase in molar volume (from 31.92 cm3mol−1 to 34.32 cm3mol−1) were demonstrated. Moreover, the refractive index is attained at an average value (1.50). The glass structure was studied using infrared spectroscopy, which elucidated an increase in N4 (33.2%–37.5 %) and an increase in NBO (15.3%-18.4 %). Bewitshingly, the charge transfer of Cr6+ ions, at high energy (347 nm), was explored. This, in turn, leads to a proper investigation of glass absorption edges that undergo a blue shift of about 1.25 eV. Adding 3d-transition metal ions affects crystal field splitting energy and interelectronic interaction within the d-orbitals of Cr ions. Finally, ESR data confirmed the Cr5+ state (with ESR signal at 1.92) and Cr3+ state (with ESR signal at 4.6, 4.07 and 2.04) of chromium ions. Such a cohesive investigation of the structure, optical and magnetic properties of 3d-transition metal ions-bearing chromium barium borate glass paved the route toward utilization of these samples in the optoelectronic realm.

Batch testing and noise rate optimization of MRPC3b for CBM-TOF/STAR-eTOF

The Compressed Baryonic Matter (CBM) experiment is one of the major scientific spectrometers of the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt. As one of the core sub-systems in CBM experiment for charged hadron identification, the Time-of-Flight (TOF) system is required to have a time resolution better than 80 ps. According to the final state particle flux distribution, the CBM-TOF will be constructed with several types of Multi-gap Resistive Plate Chambers (MRPC). In the outer region of the TOF wall where the particle fluxes are around 1 kHz/cm2, MRPCs with ultra-thin float glass electrodes are considered as a cost effective solution. MRPC3b prototypes have been developed and tested with excellent performance which could meet all the requirements. Before the construction of CBM-TOF, approximately 80 MRPC3bs are assembled for the STAR endcap TOF (STAR-eTOF) upgrade at RHIC as part of the FAIR Phase-0 programs for CBM-TOF which provides a valuable opportunity for detector stability test under high flux environments. This paper will introduce the batch test of the MRPC3bs for STAR-eTOF upgrade. Time resolution of better than 70 ps and efficiency of around 95% are achieved. Notably, during the batch test, it has been observed that the noise rates of the two edge strips in each counter are significantly higher than those of the middle strips. Simulations with Computer Simulation Technology (CST) Studio Suite are carried out and several kinds of MRPC prototypes are designed and tested accordingly. Based on the simulation and test results, the design of the MRPC3b has been further optimized by modify the shape and position of High-Voltage injection pad and increasing the distance between the glass edge and both end strips, resulting in a significant suppression of noise rates in the edge strips.

Light along curves: photonic shaping tools

A structured light concept is reported enabling to distribute a large number of focus copies at arbitrary positions in a working volume. Applying this holographic 3D-beam splitter concept to ultrashort laser pulses allows to deposit energy along accelerating trajectories in the volume of transparent materials. Based on the entirety of the volume modifications created in this way, the material can be separated, for example, to create chamfered glass edges. These photonic tools impress with enormous versatility, which enable equally diverse application strategies ranging from cutting and welding to data storing.

Numerical analysis of glass edge chipping by impact loading

This study presents numerical analyses for edge chipping by impact loading. As a numerical analysis method, we extend Particle Discretization Scheme Finite Element Method (PDS-FEM) developed by the authors to be able to simulate fracture due to impact loading. We performed simulations targeting edge chipping of soda-lime glass by impact of rigid steel sphere and examined the crack morphology while varying the diameter of the impactor, the impact velocity, and the impact distance. The proposed method successfully simulates the 3D complex crack pattern on edge chipping such as Hertzian cone crack and conchoidal chip scar. The method also reproduces the change of crack morphologies depending on the impact force and the impact distance. Also, a series of numerical analyses is presented to reveal the effect of the impactor geometry on the chip dimensions. The height of chip is independent of the impactor geometry while the width of chip depends on it. According to the agreement with experimental results, it is confirmed that the proposed method is capable of realizing edge chipping due to impact loading.

High temperature near IR spectral absorption of clear SiO2‐based glasses

AbstractExperimental high temperature near infrared (NIR) absorption spectra of different SiO2‐based glasses, including lead silicate crystal glass, clear soda lime silicate (SLS) glass and fused silica with low and high OH content, are compared. The more polarizable the glass, the stronger is the increase in the high temperature NIR absorption at wavelengths < 2 µm, involving a red shift of the optical bandgap edge with increasing temperature. It appears that the modified glassy Urbach's rule provides a framework for describing the temperature red shift of the absorption edge of lead silicate crystal glass, even above Tg. This red shift causes a 4–7 times lower Rosseland thermal radiation conductivity of lead crystal glass melts compared to clear SLS glass melts. Low OH fused silica is practically transparent for NIR thermal radiation, also at high temperatures above Tg. Incorporation of water in fused silica increases the NIR absorption in the spectral region 1.7–3.4 µm, for all temperatures. An upper limit of the diffusion coefficient D of water in fused silica was estimated from the time to measure the high temperature NIR spectra of thin (∼2 mm) samples: D < 4 * 10−10 m2/s at temperatures up to around 2000°C.

Axial multi-focus stealth cutting method based on the fractional Fourier transform for quartz glass

Aiming at the problems of quality defects, low efficiency, and insufficient flexibility in the traditional glass cutting process, this paper proposes a holographic ultrafast laser axial multi-focus stealth cutting method. By changing the fractional Fourier transform order, combined with the 3D-GSW iterative optimization algorithm, the spatial position and energy of the axial multi-focus can be flexibly adjusted. Focusing the axial multi-focus inside the quartz glass not only improves cutting efficiency but also eliminates the defects such as chipping and microcracks. This processing method has good prospects for applications in optical material processing and optical manipulation. A holographic ultrafast laser parallel processing system was built, and the diffraction efficiency and light intensity uniformity of the axial multi-focus were simulated and analyzed. Using this stealth cutting method, a single scanning cutting of quartz glass (200 μm) was successfully achieved with intact glass edges and no microcracks. The minimum roughness of the cutting section is 2.21 μm.

A review of the FIVA project: Novel windows employing vacuum glazing products

Vacuum glazing products have been in development for the past decades. Such glazing products regularly feature two parallel glass panes that have a small, evacuated gap in their interstitial space. To maintain the vacuum and the form of the glass product, regularly vacuum tight edge seals and a grid of distance pillars are integrated. During the years of development, the major focus was set on the production and durability aspects of the glass products, but relatively few efforts had been conducted towards the integration of such glass products into window constructions. Employing typically used double- and triple glazing windows’ frames does not represent a feasible option. This is due to the specification given by vacuum glazing products, such as their small thickness and the requirement for sufficient glass edge coverage due to the major thermal bridge adjacent to the edge seal.The authors, together with major players from the window producing industry, started a R&D effort that targeted disruptive new concepts for vacuum glass windows. Four different designs were developed that not only integrated vacuum glass products, but also featured unusual opening patterns, the latest generation of electrically driven fitting products, and specific seals. The thermal and acoustical performance of the prototypes was improved during the development via employment of numeric thermal simulation and lab testing. The present contribution illustrates the four prototypes and their performance, which – for instance – pertaining to the UW-value is down to 0.6–0.7 W · m−2 · K−1 at a glass thickness of less than 1 cm.

Laminated Glass Plates Subjected to High-Velocity Projectile Impact and Their Residual Post-Impact Performance

This study aims to analyze the performance of laminated glass against ballistic loading and investigates its residual load-bearing capacity. Two groups of specimens were used in quasi-static four-point bending experiments, first without prior ballistic damage and then with it. The main objective was to compare the load-bearing capacity of these two groups to see the effect of ballistic damage. Three different layer compositions were used. The ballistic loading was conducted using an in-service 9 mm bullet fired from a semiautomatic carbine with the glass specimens hanging on steel ropes in a free boundary setup. Numerical simulation and analytical methods were used and validated against the measured response of the undamaged specimens. The simulations were in good agreement with the experimental results. All of the glass specimens were able to withstand the ballistic loading, and the subsequent performance during the quasi-static bending loading was similar to that of the undamaged specimens. The quality of the glass edges seemed to be more important than ballistic damage. The front-plate damage played a negligible role, and the back-plate damage needed to be extensive to influence subsequent performance. Provided that ballistic damage is mainly localized only to the centers of the plates, it did not affect the post-impact loading capacity.

Three-dimensional modelling on the impact fracture of glass using a GPGPU-parallelised FDEM

Due to the brittleness and the wide use of glass in modern engineering applications, its vulnerability to impact actions and the corresponding fracture behaviour attracted growing attentions from academics and engineers. In this study, impact fracture responses of glass have been modelled and simulated using a 3D GPGPU-parallelised hybrid finite-discrete element method, i.e., the FDEM. Glass is discretised into discrete elements where finite element formulation is incorporated, enabling accurate predictions on contact forces and structural deformation. A cohesive fracture model accounting for the rupture of glass is implemented, and numerical examples are presented and validated with results from literatures. The influence of impact velocity, boundary condition and projectile nose shape on the fracture of glass has been investigated. It is found that: (i) fracture pattern changes with the change of velocity; (ii) a rigid boundary support can be used should no damage occur in the edge of glass; (iii) under the same circumstance, a larger contact surface results in more severe damage. The GPGPU-parallelised FDEM provides a practical, efficient and robust computational approach in analysing the impact transient dynamic behaviour of glass in 3D.

Development and behavior of a thin fitting connection for lamination with structural PVB

Intended for the construction of a double curved, frameless modular glass shell demonstrator, a stainless steel fitting connection with a trapezoidal, thin sheet laminated into the interstice of two-ply safety glass has been developed. For the bonding within the glass laminate, structural PVB interlayer is used. Various interlayer plies of different PVB types can be stacked depending on the necessary interstice thickness and the intended esthetical appearance. The fitting is designed to mainly transfer translational forces, but it also provides some bending stiffness via a crossbar supported against the glass edge. Various tests, including tension, shear and bending load application, have been performed at the Lucerne University of Applied Sciences and Arts (HSLU) to explore the structural behavior and the load bearing capacity of the fitting connection. In addition, parameter studies using finite element models were made to explore the influence of the fitting geometry, dimensions, interlayer properties and loading type on the structural behavior of this type of connection. These parameter studies and test results allow to identify further shape optimization and application possibilities of such thin, laminated fittings for load bearing glass structures.

Role of high energy [formula omitted] optical transition induced by rare earth ion ([formula omitted]) in compositional-dependent borate glass

In this contribution, borate glasses co-doped with La2O3 and a fixed ratio of Cr2O3 were produced by the melt-quenching method. The role of La2O3 on the glass characteristics was investigated, and then the optical transitions of Cr6+ were reevaluated. The low energy Cr6+ transition is well defined, while the high energy Cr6+ is often immersed in the glass because of its vicinity to the glass edge. The novelty of this paper is unveiling the high energy Cr6+ transition, which is often hidden in earlier reports, through both La2O3 doping and deconvoluted process. ESR was additionally used to confirm this dissertation. The addition of La2O3 led to a blue shift in the absorption edges (～ 6 nm) and regularly activated the role of novel identified high energy Cr6+ transition (at 337 nm) through a wide optical gap of size ～ 3.05 eV and modified refractive indices. Thus, using these glasses as a base material for UV optics is possible.

Two-Step Glass Molding Process for Forming Glass Edges with Obtuse Angles for Mobile Displays.

The domain of edge displays with 2.5D or 3D curved designs has been expanded to improve user convenience. The currently available 3D cover glass offers a limited curvature radius of at least 5 mm and a curvature less than 88°, due to limitations in the undercuts and formability of parts. The development of a full 3D cover, applicable to next-generation displays, requires cover glass molding technology with a curvature exceeding 90°. Here, a mold design and molding process, which addresses the current limitations by dividing the existing glass molding press (GMP) process into two stages, is proposed. The bending geometry of the glass prepared on the basis of the proposed mold design plan during single-step compression forming and two-step compression forming was predicted using commercial analysis software. A molding product with a curvature radius of 2.5 mm and an angle of curvature of 138.9° was produced when process conditions with bending by up to 180° with no damage were applied during actual forming experiments. Further research on annealing and cooling processes of GMP is expected to enable the design and process implementation to manufacture curved glass with a single curvature of at least 90° and multiple curvatures.

Impact of Cutting Process Parameters on the Mechanical Quality of Processed Glass Edges

The inspection of glass edges is gaining in importance in research, as the strength of a glass edge has been found to be highly dependent on its processing. Glass edges are produced by cutting. Depending on their type, they may be additionally seamed, ground or polished in the grinding process. Cutting and grinding processes create mechanical interference in the brittle material, leaving flaws and cracks in the edge surfaces. The current state of the art presents cutting process parameters which correlate with minor flaws and a high glass edge strength. Research at the Technische Universität Dresden aims to understand the impact of grinding processes and to develop parameters for processing glass edges with a defined and reproducible optical and mechanical quality. To isolate observations of the grinding process from the cutting process, this paper examines the impact of cutting process parameters on further processed glass edges. Several different cutting parameter-sets formed the basis of various test series that were performed on specimens whose glass edges were processed by the same manufacturer. This paper presents an optical and mechanical examination of the specimens. The results show that higher optical and mechanical qualities of the cut edge and arrised edge can be obtained by adjusting the cutting process parameters. It had no major impacts on smooth ground and polished edges.

The Performance of Vacuum Insulating Glazing Units Subjected to a Soft Body Impact

The Vacuum Insulated Glazing is a highly thermally insulating structure consisting of two (or more) glass sheets, separated by an evacuated gap, and sealed hermetically at the glass edges. An array of support pillars maintains the separation of the panes under the constant load of atmospheric pressure. The performance and durability of the VIG, in terms of thermal loads and atmospheric pressure, has been well studied and ISO Standards have recently been published (ISO 19916-1:2018 and 19916-3:2021). However, the mechanical performance of the VIG, especially when exposed to dynamic loads, has not been dealt with in the scientific literature. The goal of this work is to investigate the mechanical performance of VIG’s subjected to soft body impact and gain insight into the failure mechanisms of the VIG when exposed to dynamic loads. Measurements of the surface stress on the glass were performed, when the VIG is subjected to the twin-tire pendulum impact test, as outlined in the Standard DIN EN 12600:2002. Two VIG units and one laminated VIG unit were tested and the results were compared to numerical data of a monolithic glass pane. It was found that the VIG failed at drop heights much lower than that prescribed in the Standard. An examination of the glass fracture patterns highlighted an origin of fracture caused by the contact of pillar-to-glass.

Cutting glass with photons

AbstractA comprehensive report is provided here about the state of the art and recent advances in cutting glass with ultrashort pulsed lasers. Several optical concepts are discussed that enable single‐pass, full thickness modification of transparent articles in the most diverse geometries, such as architectural glass or glass tubes. We also highlight the trend towards tailored glass edges for substrate protection with laser‐fabricated chamfers. A completely new beam‐shaping concept is used here, in which a large number of focus copies are distributed along any edge shape in order to combine cutting and chamfering within a single laser process.

Laser strengthening of additive manufactured edge seal for vacuum insulated glazing with micro-size glass frit

Sealing of glass edge is a key step in developing cost-effective and durable vacuum insulated glazing for the drive towards net-zero energy buildings. To achieve a high-strength sealing with scalable and low-cost processing, we investigated a novel sealing method based on additive manufacturing and laser process and reported quantitative analysis of the laser assisted method sealing strength and the requirement of vacuum insulation glazing. Micro-size glass frits in printing ink and a continuous-wave laser curing were employed to allow the formation of a hermetic bonding layer with low thermal budget. Controlling various sealing parameters including laser traveling speed, spot diameter, and laser power, the water seepage and mechanical strength of the resulting glass-to-glass bonding were examined. Through the response surface methodology, we identified the optimized sealing condition where the bonding strength reached 5.68 MPa. A comparation of the bonding strength between thermal sealing method and laser-assisted method has been analyzed as well.

Protecting the edge: Ultrafast laser modified C-shaped glass edges

A procedure and optical concept is introduced for ultrashort pulsed laser cleaving of transparent materials with tailored edges in a single pass. The procedure is based on holographically splitting a number of foci along the desired edge geometry including C-shaped edges with local 45° tangential angles to the surface. Single-pass, full-thickness laser modifications are achieved requiring single-side access to the workpiece only without inclining the optical head. After having induced laser modifications with feed rates of ∼1m/s, actual separation is performed using a selective etching strategy.