Bead Grinding Research Articles

Scalable Fabrication of Silicon‐Graphite Microsphere by Mechanical Processing for Lithium‐Ion Battery Anode with Large Capacity and High Cycling Stability

AbstractIn order to combine the high stability of graphite and the large theoretical capacity of silicon, silicon‐graphite composites attract tremendous attentions. However, the cycling stability is still a bottleneck hindering their commercialization due to the large volume expansion and poor interface compatibility. In this study, the bead grinding method is used to break micro‐sized silicon and graphite particles by strong shear force simultaneously, inducing the solid‐solid interface reaction between fresh silicon nanoparticles and graphite nanosheets. Subsequently, an evaporation induced self‐assembly happens in spray drying process, allow for scalable synthesis of Si‐graphite microsphere. The silicon‐graphite microsphere (Si−G microsphere) delivers an excellent cycling performance, with a reversible capacity of 1895 mAh g−1 at a current density of 0.5 A g−1 over 500 cycles and a capacity retention of 99.8 %. Moreover, the pouch‐type full battery of Si−G microsphere/graphite||LiNi0.5Co0.2Mn0.3O2 exhibits remarkable cycling stability with the capacity retention of 79.3 % after 800 cycles. The manufacture process using commercial raw materials and simple mechanical strategy demonstrates great potential for the low‐cost and scaled synthesis of high‐performance silicon‐graphite anodes.

A Robotic Grinding Motion Planning Methodology for a Novel Automatic Seam Bead Grinding Robot Manipulator

Industrial robotics is a continuously developing area of in-depth robotics research, as industrial robots have demonstrated to possess advantages in the robotic automation solutions in the industrial automation applications. In this paper, a novel automatic seam bead grinding robot manipulator with the integration of machining and measuring is proposed and an experimentation platform is developed for the robotic removal of the seam weld beads at welded pipe ends. Also, a robotic grinding motion planning methodology, which consists of a robotic operation process motion planning approach and a robotic seam bead grinding method, is presented for the appropriate motion planning and applications of the operational processes. Furthermore, the effectiveness of the robotic grinding motion planning methodology and the superiorly operational manipulation performance of the proposed robot manipulator are verified through a robotic grinding experiment for the removal of external seam weld beads at a helical welded pipe end.

Anomalous Size Distribution of Chiral Crystals during Deracemization by Grinding

With the use of a generalized Becker–Döring model, we study the anomalous crystal size distribution (CSD) of chiral crystals during deracemization (chirality conversion) under grinding. Ultrasound grinding yields a large amount of small clusters, and large crystals can grow due to the temporal large supersaturation, which leads to the anomalous spread of the CSD. Glass bead grinding produces crystals of various sizes, and the steady CSD is maintained. The amplification of the crystal enantiomeric excess is realized in both models. Therefore, temporal spread of the CSD observed in experiment is not an essential condition for the deracemization.

Particle Breakage Kinetics and Mechanisms in Attrition-Enhanced Deracemization

In this study, we report on experiments designed to deconvolute the particle breakage kinetics and mechanism from the parallel phenomena (growth-dissolution, agglomeration) in attrition-enhanced deracemization processes. Through such experiments, we derived the specific breakage rates and cumulative breakage distribution functions for three grinding methods typically used in deracemization experiments: (a) bead grinding, (b) ultrasound grinding, and (c) the combination of bead and ultrasound grinding. Subsequently, we tested these methods on their ability to induce deracemization. We show that in the conventional bead grinding process, breakage occurs mostly by fracture. This results in slow deracemization rates due to the delayed formation of submicron particles that are essential to the process. Conversely, ultrasound grinding very efficiently breaks particles by abrasion. This leads to fast generation of an abundance of submicron fragments resulting in fast deracemization. However, using ultrasound, la...

Genetically shaping morphology of the filamentous fungus Aspergillus glaucus for production of antitumor polyketide aspergiolide A.

BackgroundFor filamentous fungi, the basic growth unit of hyphae usually makes it sensitive to shear stress which is generated from mechanical force and dynamic fluid in bioreactor, and it severely decreases microbial productions. The conventional strategies against shear-sensitive conundrum in fungal fermentation usually focus on adapting agitation, impeller type and bioreactor configuration, which brings high cost and tough work in industry. This study aims to genetically shape shear resistant morphology of shear-sensitive filamentous fungus Aspergillus glaucus to make it adapt to bioreactor so as to establish an efficient fermentation process.ResultsHyphal morphology shaping by modifying polarized growth genes of A. glaucus was applied to reduce its shear-sensitivity and enhance aspergiolide A production. Degenerate PCR and genome walking were used to obtain polarized growth genes AgkipA and AgteaR, followed by construction of gene-deficient mutants by homologous integration of double crossover. Deletion of both genes caused meandering hyphae, for which, ΔAgkipA led to small but intense curves comparing with ΔAgteaR by morphology analysis. The germination of a second germ tube from conidiospore of the mutants became random while colony growth and development almost maintained the same. Morphology of ΔAgkipA and ΔAgteaR mutants turned to be compact pellet and loose clump in liquid culture, respectively. The curved hyphae of both mutants showed no remarkably resistant to glass bead grinding comparing with the wild type strain. However, they generated greatly different broth rheology which further caused growth and metabolism variations in bioreactor fermentations. By forming pellets, the ΔAgkipA mutant created a tank environment with low-viscosity, low shear stress and high dissolved oxygen tension, leading to high production of aspergiolide A (121.7 ± 2.3 mg/L), which was 82.2% higher than the wild type.ConclusionsA new strategy for shaping fungal morphology by modifying polarized growth genes was applied in submerged fermentation in bioreactor. This work provides useful information of shaping fungal morphology for submerged fermentation by genetically modification, which could be valuable for morphology improvement of industrial filamentous fungi.

713 溶接ビード研削作業をロボット化するための能動工具ホルダーの開発 : 効果的なビード研削を実現するための剛性制御(GS07-1 ロボティクス・メカトロニクス)

713 溶接ビード研削作業をロボット化するための能動工具ホルダーの開発 : 効果的なビード研削を実現するための剛性制御(GS07-1 ロボティクス・メカトロニクス)

1A1-A04 溶接ビード研削をロボット化するための能動工具ホルダーの開発(生産システム・生産機器メカトロニクス)

1A1-A04 溶接ビード研削をロボット化するための能動工具ホルダーの開発(生産システム・生産機器メカトロニクス)

1A1-F05 溶接ビード研削をロボット化するための能動工具ホルダーの開発 : 非線形力フィードバックを用いた剛性制御(生産システム・生産機器メカトロニクス)

1A1-F05 溶接ビード研削をロボット化するための能動工具ホルダーの開発 : 非線形力フィードバックを用いた剛性制御(生産システム・生産機器メカトロニクス)

Rapid and effective DNA extraction method with bead grinding for a large amount of fungal DNA.

To identify a rapid method for extracting a large amount of DNA from fungi associated with food hygiene, extraction methods were compared using fungal pellets formed rapidly in liquid media. Combinations of physical and chemical methods or commercial kits were evaluated with 3 species of yeast, 10 species of ascomycetous molds, and 4 species of zygomycetous molds. Bead grinding was the physical method, followed by chemical methods involving sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), and benzyl chloride and two commercial kits. Quantity was calculated by UV absorbance at 260 nm, quality was determined by the ratio of UV absorbance at 260 and 280 nm, and gene amplifications and electrophoresis profiles of whole genomes were analyzed. Bead grinding with the SDS method was the most effective for DNA extraction for yeasts and ascomycetous molds, and bead grinding with the CTAB method was most effective with zygomycetous molds. For both groups of molds, bead grinding with the CTAB method was the best approach for DNA extraction. Because this combination also is relatively effective for yeasts, it can be used to extract a large amount of DNA from a wide range of fungi. The DNA extraction methods are useful for developing gene indexes to identify fungi with molecular techniques, such as DNA fingerprinting.

1105 ロボットによる溶接ビード研削のための能動工具ホルダー(OS11-1 ロボットシステムと要素技術,オーガナイズドセッション:11 ロボティクス・メカトロニクスの応用)

1105 ロボットによる溶接ビード研削のための能動工具ホルダー(OS11-1 ロボットシステムと要素技術,オーガナイズドセッション:11 ロボティクス・メカトロニクスの応用)

2A1-A17 溶接ビード研削をロボット化するための能動工具ホルダーの開発

To automate bead grinding tasks by industrial robots, compliant motion of a grinding tool is necessary. However, almost industrial robots are designed on the basis of position control schemes and are not appropriate for force control tasks. In order to solve the problem, this paper proposes an active tool holder which adjusts the tool position independently of robot motion. The developed active tool holder consists of a brushless DC motor, a ball screw and a parallel links mechanism. The translational motion of the grinding tool is realized by the compact mechanism. A simple stiffness controller using force sensor was designed and implemented in the active tool holder to achieve compliant motion of the tool. The developed system was applied to a simple bead grinding task. Experimental results show that the system enables the smooth bead grinding tasks using industrial robots.

Fabrication of Fine AlN Particles by Pulverizing with Very Small ZrO2 Beads

Nano‐sized aluminum nitride (AlN) powders can enhance the sinterability of AlN ceramics. The present work examined the pulverization and dispersion of AlN powder using ZrO2 beads of 0.1 mm in diameter as grinding medium in order to obtain nano‐sized powder for low‐temperature sintering. An attracting feature of the bead grinding is that the rotor creates centrifugal and shearing forces, which lead to efficient pulverization that exceeds the conventional grinding limit. The AlN powder with agglomerates and average particle size of 0.38 μm was broken up into more homogeneous particles with a narrow particle size distribution after 90 min of grinding. Qualitative examinations of the powder by transmission electron microscopy and BET indicated that the particle size was 50–100 nm and specific surface area was 70 m2/g.

Stochastic dynamic programming applied to planning of robot grinding tasks

This paper proposes an intelligent manufacturing system that can make decisions about the process in light of the uncertain outcome of these decisions and attempts to minimize the expected economic penalty resulting from those decisions. It uses robot weld bead grinding as an example of a process with significant process variation. A three tier hierarchical control system is proposed to plan an optimal sequence of grinding passes, dynamically simulate each pass, execute the planned sequence of controlled grinding passes, and modify the pass sequence as grinding continues. The top tier, described in this paper, plans the grinding sequence for each weld bead, and is implemented using stochastic dynamic programming, selecting the volumetric removal and feedspeed for each pass in order to optimize the satisfaction of the task requirements by the entire grinding sequence within the equipment, task, and process constraints. The resulting optimal policies have quite complex structures, showing foresight, anxiety, indifference, and aggressiveness, depending upon the situation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Predictive Control of a Robotic Grinding System

This paper describes a modified predictive controller that has been interfaced with the robotic weld bead grinding system currently under development at The Charles Stark Draper Laboratory. The objective of the predictive control in the grinding system is to invert the previously modeled grinding dynamics. This is accomplished via a link between the controller and a grinding simulator that has been developed, based on an exchange of geometric and force data used by both algorithms. The interface utilizes vision data obtained from previous grinding passes to generate a force trajectory used by the robot on the subsequent pass. This trajectory is precomputed by the predictive controller to yield a specific weld bead shape. Due to system limitations, measurement noise, and modelling errors, the beads are not ground perfectly flat. However, their cross sectional area (or height) variations are reduced significantly. Thus, the bead is flattened although not completely.

Development and Control of an Automated Robotic Weld Bead Grinding System

In a robotic weld bead grinding system there are large interaction forces between the robot and the workpiece. Jigging errors and robot compliance make position control unreliable. Instead, metal removal can be controlled by controlling the power applied to the workpiece. The approach used in this work has been to develop a nonlinear force control law for the PUMA 560 robot and implement a structured light vision system that measures material volume in real time. A power trajectory planner has also been incorporated into the system permitting the delivery of a power (the product of force and wheel speed) trajectory to the weld bead. The resulting system is able to plan and execute a multi-pass grinding sequence for removing a weld bead.

Verification of a Dynamic Grinding Model

Many applications of industrial robot automation can be made possible or improved with the introduction of a force feedback system. The task of weld bead removal is being studied in an effort to develop a real time force controlled intelligent system. The process of weld bead grinding must be analyzed and modelled to develop a weld bead removal system. Previous research has developed and verified static models of grinding. This paper describes a dynamic model developed from the grinding characteristics demonstrated previously. An experimental grinding system was built and the measured process behavior was compared with a grinding simulation based on the dynamic model. The profile of the specimen was measured prior to and subsequent to grinding. The initial profile was used as an input to the simulation, and the output from the simulation was compared with the final measured profile. A variety of conditions was tested. For typical mean cut depths of 0.10 mm the simulator predicted the final height of the grinding specimen within a standard deviation of 0.02 mm. The dynamic model was verified within 10 percent of the actual results.

Low cycle fatigue properties of weld metals for structural carbon steel.

Completely reversed strain controlled low cycle fatigue properties at room temperature are investigated for structural carbon steels and weld metals. The weld metal specimens deposited by gas metal arc welding (GMAW) were taken from multi-pass weld metal such that gage length consisted entirely of the weld metal. The results indicate that there is a trend toward reductions in the low cycle fatigue life of weld metals as compared with the base metals. They are explained in terms of local plastic strain concentration by lack of uniformity of the multi-pass weld metals. The weld metals have not the same mechanical properties anywhere as confirmed by hardness distribution, and the fatigue crack grows preferentially through temper softening region of multi-pass welds. This study leads to the conclusion that fairly accurate estimates of the low cycle fatigue life of structural carbon steel weld metals are obtained by the results of base metals from the ratio of temper softening region. It is also confirmed by experiment that low cycle fatigue life of multi-pass welds can be improved significantly using half bead grinding technique and/or welding conditions.