磨料水射流技术在特殊管道的应用

采用磨料水射流进行清洗作业技术是较为环保,经济,高效的一种工艺。本文介绍了磨料水射流清洗技术的原理以及在管道内的应用实例。     

奢料浆体连续射流循环系统研究与应用

磨料射流在除漆除锈中的清洗效果、清洗效率及运行成本都优于纯水射流,然而目前使用的磨料射流系统多为间断不连续供给磨料、而且磨料不易循环使用,因而限制了磨料射流的使用范围。采用该系统能将磨料循环使用,显示出磨料射流更多的优势。     

奢料浆体连续射流循环系统研究与应用

磨料射流在除漆除锈中的清洗效果、清洗效率及运行成本都优于纯水射流,然而目前使用的磨料射流系统多为间断不连续供给磨料、而且磨料不易循环使用,因而限制了磨料射流的使用范围。采用该系统能将磨料循环使用,显示出磨料射流更多的优势。     

旋转磨料射流除锈实验研究

采用锈蚀钢板为试件,进行前混合式旋转磨料射流清洗试验.找出了喷嘴出口段长度、喷距、叶片导向角、叶轮长度等参数对清洗效果的影响规律.确定了旋转磨料射流进行表面清洗的压力应用范围为(1.5 ～ 8)MPa.     

引射式高压水磨料射流制作与工作原理

本文重点介绍高压水磨料射流的分类和引射式高压水磨料射流制作与工作原理、工作效率和制作方式,使用户和读者更好地利用高压水磨料射流,高效率地完成工业清洗任务。     

石化钢结构防腐涂装前表面清理方法的选择

从石化企业实际出发,对钢结构与设备防腐涂装前表面清理方法进行对比,包括干啧砂、湿啧砂、磷化、酸洗、手工与动力工具除锈、高压磨料水射流清洗等清洗方法,从中提出如何合理地选择清理方法.     

纯铁零件镀镍弊病分析及改进

对电工纯铁材料制成的继电器磁路零件电镀镍后镀层表面出现的浅红色和黄斑弊病进行了探讨。采用扫描电镜分析方法,对置换铜引发的镀层氧化变色问题和振光去毛刺工序磨料残留引发的发黄问题进行分析,并提出对工艺设备进行改进,采用超声波清洗磨料残留物的解决措施,故障得到了解决。     

某后混合磨料水射流除锈喷嘴的流场数值模拟

后混合磨料喷嘴内部流场流速大,沿径向速度变化较快,且喷嘴内部存在多相物质,所以依靠试验和理论去进行喷嘴的流场计算研究,从而优化喷嘴性能是十分复杂不便的。本文基于fluent仿真软件,针对某种清洗除锈功能的后混合磨料喷嘴,在较少简化其物理模型基础上,合理设置边界条件,通过数值计算得到喷嘴内部流场。最后利用流场的数值计算结果得出该种喷嘴的最佳工作区域位于远离磨料入口侧,出口的中间区域因磨料与高压水在混合腔内速度差别过大,磨料粒子很难进入高速水流内部,导致中间区域工作性能不佳,研究结论可为喷嘴的结构性能设计提供一定的理论支撑。     

一种快速回收陶瓷结合剂cBN砂轮中高纯磨料的方法

研究开发了陶瓷结合剂cBN砂轮中磨料的提取技术,该技术得到的cBN磨料晶型好,纯度高,工艺简便快捷,回收的磨粒可进行重复使用而不影响磨粒固有特性。回收筛分后的cBN磨料制备的砂轮无论是在硬度、粗糙度、圆度、寿命上均与首次使用的新磨料制备的砂轮性能基本相同,由此可知回收筛分后的cBN磨料与首次使用的新磨料具有相同的性能,在后续的多次使用中不影响cBN砂轮产品的品质。     

易燃易爆环境下冷切割技术及其应用研究

在石油化工及危化品生产中，油气介质具有易燃易爆性等特点，较易引发安全事故。针对易燃易爆环境下，有计划维修与事故情形下的应急切割，指出了采用冷切割技术的必要性。基于磨料水射流切割的技术特点，分析了磨料水射流切割技术在易燃易爆环境下的适应性。探讨了磨料水射流应急切割的应用模式，分别说明了其磨料前混合与后混合技术形式的优缺点与应用场合，以及应急切割场合的磨料水射流切割装置的防爆模式与集成模式的特性及方法。提出了射流冷切割技术在专用切割执行机构开发、提高装置可靠性的技术攻关、新型射流开发等方面的新发展趋势。     

Mechanism of Cf/SiC hole making with high shape precision using abrasive waterjet based on response surface method

This paper aims to explore the accurate control of hole shape for AWJ hole-making of C_f/SiC based on experimental and mathematical analysis methods, and the influence mechanism involved is emphatically analyzed. The results reveal that D_difference is most influenced by the standoff distance, followed by the traverse speed, while it is less influenced by the pressure and the abrasive flow rate. The traverse speed, pressure and abrasive flow rate affect the D_difference by changing the total energy of the jet; while the standoff distance mainly affects the D_difference by changing the effective impact area, which is fundamentally different from other process parameters. In terms of interaction effects, decreasing the traverse speed and increasing the waterjet pressure can amplify the effect of interaction with the involvement of the standoff distance on the D_difference. Based on the established D_difference model and D_offset model, a control method that can gain acquired hole shape is finally obtained for selecting the process parameters of AWJ machining.     

Material removal mechanisms of ceramics turned by abrasive waterjet (AWJ) using a novel approach

Ceramics are the most typical difficult-to-machine materials for high-performance applications. The paper utilized AWJ to turn the alumina ceramics. A prediction model of the depth of penetration (DOP) after AWJ turning of alumina ceramic was established. The variation trends of predicted and experimental results with respect to process parameters were consistent. Within the range of this study, it may be stated that the developed model can achieve good predictions both qualitatively and quantitatively. The material removal mechanism of alumina ceramics turned by AWJ was also analyzed. The turned surface topography analysis showed that the main removal mechanism of alumina ceramics in turning was plastic shearing at a shallow nozzle tilt angle but brittle fracture at a larger nozzle tilt angle. Through the analysis of chip morphology during AWJ turning, it was proved that the removal mechanism of ceramics turned by AWJ was mixed (brittle fracture and plastic shear). Gained predicted model and material removal mechanisms will provide more details to understand and improve the AWJ turning technology.     

Abrasive water jet machining and mechanical behavior of banyan tree saw dust powder loaded polypropylene green composites

Banyan tree saw dust powder (BSD) filled Polypropylene (PP) green composites have been fabricated with varying amounts viz., 0%, 20%, and 40% of BSD particulate filler by using a co‐rotating twin screw extruder followed by injection molding. The mechanical properties such as surface hardness, tensile behavior, and impact strength of the fabricated PP/BSD green composites have been studied in order to standardize the composites. Abrasive water jet (AWJ) machining has been reported mainly for ceramics, concrete, and glass but not much literature is available on AWJ machining of polymer composites. This research is aimed at examining the AWJ machining of green polymer composites. The effect of BSD loading on the AWJ machining behavior of the PP/BSD green composites has been investigated. Furthermore, the effect of addition of 4% maleic anhydride grafted PP (coupling agent) and 4% talc (mineral filler) on the machining behavior of PP/BSD composites has also been evaluated. Surface roughness and optical micrographs of the AWJ cut composite specimens were examined to assess the effect of BSD content, AWJ traverse speed and pressure on the machining behavior of the composites. In order to probe the mechanism of AWJ machining behavior of PP/BSD composites, the kerf width and taper have been measured and results are correlated. POLYM. COMPOS., 37:1754–1764, 2016. © 2014 Society of Plastics Engineers     

氧化铁涂衣磨料性能的实验研究

实验研究了氧化铁涂衣磨料与未涂衣磨料的单颗粒抗压强度和亲水性;对分别用它们制成的涂附磨具(砂布)的磨削性能进行了对比实验.证明了涂衣磨料的性能明显的优于未涂衣磨料,用涂衣磨料制成的涂附磨具的磨削性能好,使用寿命长,较显著地提高了磨具的质量,具有推广应用的价值.     

Wear characteristics of single-layer cBN abrasive tools using ultrasonic vibration–assisted induction brazing techniques

Single-layer brazed superhard abrasive tools have been widely employed in grinding of difficult-to-machine materials in aerospace, aiming at the improvement of the grinding performance and quality. However, the chemical metallurgical reaction during conventional induction brazing (CIB) is severe, and the brazing quality is poor, resulting in a rapid wear and thus reducing service life of abrasive tools. In this case, the single-layer brazed cBN abrasive tools were fabricated using ultrasonic vibration-assisted induction brazing (UVAIB) technology, and the wear comparative experiments of Ti–6Al–4V alloys was carried out using UVAIB and CIB abrasive tools. Results indicate that compared to the CIB abrasive tool, the UVAIB abrasive tool has the higher average exposure height of abrasive grains, lower grinding forces and more stable grinding force ratio during wear processes. Meanwhile, the UVAIB abrasive tool has a slowly decreased exposure height of abrasive grains, a superior wear state and low proportion of macro-fracture as the material removal volume raises. In addition, UVAIB abrasive tool possesses micro-cracks at the top of abrasive grains, leading to micro-fractures of abrasive grains to improve the self-sharpening ability and grinding performance.     

纳米TiO2对PTFE基复合材料磨粒磨损性能的影响

利用自行改制的销-盘式磨粒磨损试验机测定纳米TiO2用量对聚四氟乙烯（PTFE）复合材料试件在干摩擦滑动条件下的磨粒磨损性能。考察了载荷、磨粒、转速等参数的变化对试件摩擦学性能的影响。结果表明,在实验条件下,纳米TiO2／PTFE复合材料的抗磨粒磨损性能,以纳米TiO2质量分数为2％时,填充PTFE复合材料抗磨损性能最好。随纳米TiO2用量的增大,抗磨损性能有所减弱。在载荷、磨粒、转速等参数的变化对PTFE复合材料耐磨性的影响中,磨料粒度对磨损的影响最大,转速的影响最小。     

Morphological evolution and grinding performance of vitrified bonded microcrystal alumina abrasive wheel dressed with a single-grit diamond

Dressing experiments under different conditions were carried out on a vitrified bonded microcrystal alumina abrasive wheel with a single-grit diamond dresser. The grinding performance of the as-dressed abrasive wheels was investigated. The dressing force, grinding force and the surface morphology of abrasive wheel and machined workpiece were studied to shed light on the relationship among the dressing processing vectors, morphology of abrasive wheel and the grinding performance. The results obtained show that the dressing forces increase with the increasing volume of the abrasive wheel material removed per unit time. The sensitive analysis reveals that the dressing feed speed take a greater effect than the single dressing depth on the dressing force. The self-sharpness of vitrified bonded microcrystal alumina abrasive wheel brings into some functions under certain dressing conditions, but a deep dressing depth would lead to an excessive abrasive self-sharpness, i.e. abrasive grits fall off and embed into the workpiece surface.     

蓄能式前混合连续磨料水射流系统

蓄能式前混合连续磨料水射流系统采用了两个蓄能器,工作时蓄能器隔膜一端为液压油,另一端为磨料浆体,通过小型液压泵站使蓄能器腔体内产生的液压油压力变化,进而带动蓄能器隔膜运动实现蓄能器腔内磨料浆体的吸入和排出,两个蓄能器腔内的磨料浆体交替吸入和排出能实现磨料浆体的连续排出,排出的磨料浆体通过高压胶管输送至喷枪,通过喷嘴进行喷射。试验和实际应用表明该系统工作稳定、磨料浆体输送均匀,可实现长距离输送和系统连续工作,整个系统采用自动控制,操作简单方便。     

Molecular dynamics simulation of SiC removal mechanism in a fixed abrasive polishing process

Precision polishing of mono-crystalline SiC wafers on a fixed abrasive pad is investigated by double-nano-abrasives cutting at micro/nano scale in this report. Prior to this report, a single abrasive approach in molecular dynamics simulation had been employed to illustrate the material removal mechanism in SiC polishing process, which is quite different from the real situation of the fixed abrasive polishing process. Cutting depth and spacing of abrasive particles in a fixed abrasive pads were tested to gain insights on phase transformation, subsurface damage, surface quality, material removal and friction characteristics of polished SiC wafers by molecular dynamics simulation. By following the coordination number and radial distribution function, we clearly see that the number of phase transformation atoms caused by cutting and abrasion increases with the cutting depth of nano-abrasives on the surface of SiC workpiece. Simulation results also suggest that the phase transformation of the SiC crystal phase increases with the lateral spacing of abrasive particles in pads, while does not change much with the increase of the longitudinal spacing. It is also found that the deeper the abrasive cutting depth, the deeper subsurface damage, resulting more materials’ removal from SiC workpiece. The lateral and longitudinal abrasive spacings lead to little change the depth of subsurface damage on the wafer in MD simulation for a fixed double abrasive polishing. The surface roughness is better with the larger lateral abrasive spacing, but no clear correlation with the longitudinal abrasive spacing.     

超精密表面研抛磨粒的研究进展

半导体材料的超精密加工是一种获得高表面质量和表面完整性的加工技术,研抛磨粒是实现半导体材料超精密加工的关键耗材之一.从研抛磨粒的组成方式和结构特点,概述了研抛磨粒的研究现状和发展趋势.首先,构建了研抛界面内半导体材料工件-研抛磨粒-研抛垫的接触模型,讨论了研抛磨粒的材质、形状、浓度、粒径等因素对半导体材料研抛质量和研抛...