基于混沌理论砂轮磨钝过程声发射信号试验研究

针对砂轮磨钝过程中声发射信号的非线性特性,通过采集到的砂轮初期、稳定、严重三个不同磨损阶段的声发射信号,在混沌理论的基础上,提取砂轮磨钝过程声发射信号的最大Lyapunov 指数、关联维数以及K熵这三个特征量并进行计算、分析。结果表明,砂轮磨钝过程声发射信号的最大Lyapunov 指数、关联维数和K熵与砂轮磨损阶段存在着对应关系,可以用这三个混沌特征量来对砂轮的不同磨损阶段进行表征,为运用声发射信号实现砂轮磨钝过程的检测提供了一种新的思路。     

浅谈配变电监控系统的开发设计

重点对配变电监控系统展开设计研究,首先分析配变电网监控体系的结构,给出完整的层次划分和体系结构设计方案,并在此基础上完成了对监控终端的设计,从硬件设计,软件设计进行了设计应用和分析,对于进一步提高配变电网监控终端的应用水平和提升配变电网管理水平具有一定的借鉴意义。     

基于VMD-PNN的砂轮钝化声发射检测

在磨削加工过程中,加工刀具即砂轮会发生钝化现象,砂轮表面磨损影响加工精度和工件质量,需要及时检测并修整。磨粒的塑性变形、破碎、断裂等会产生声发射信号,能够作为精确识别砂轮钝化状态的依据,且不易被噪声干扰,因此提出一种基于变分模态分解（Variational Mode Decomposition,VMD）和概率神经网络（Probabilistic Neural Network,PNN）的砂轮钝化声发射检测方法。VMD可以将原始信号分解为多个本征模态函数（Intrinsic Mode Function,IMF）分量,筛选其中峭度较大的分量重构即得到声发射信号。声发射检测的关键是特征参数的选取,在相关研究基础上本文提出了声发射包络能量占比作为一个重要的特征参数,并选取了共5种特征参数,构建出5维特征向量数据集,输入到PNN中进行训练,经过测试识别准确度达到94.5%。该方法建立了声发射信号特征参数与砂轮不同钝化状态的关系,能够对砂轮严重钝化状态给出准确预警,具有实际应用价值。文章比较了声发射信号不同特征参数用于识别砂轮钝化状态的准确度,对特征参数的选用具有参考意义。     

AGT型案秤检修时退桥刀方法

ＡＧＴ型案秤在商业贸易中有着广泛的用途。它属于移动式杠杆秤的一种 ,随着使用时间及频度的增加 ,其杠杆 (刀架 )上的四把桥刀会逐步磨损、崩裂、锈蚀、变钝等。这些因素会直接影响到秤的准确度、灵敏度、从而导致计量性能失准 ,故需要计量器具检修部门修复。检修时一般是将杠杆 (刀架 )上的四把桥刀调换新刀 ,以提高其灵敏度等。从而保证恢复其计量性能。当然刀刃磨损不大的也可退下桥刀在砂轮上把桥刀刀刃磨锋利后再安装上继续使用。而修理时 ,传统的退刀方法是敲击法 :该方法难以掌握。现介绍一种经笔者多年实践且一直在运用的实用退刀…     

居住区配电系统一体化智能信息监控平台研究

本文研究的居住区配电系统一体化智能信息监控平台,采集与监控小区变的实时运行数据,实现主辅设备、视频、消防、安防、门禁、环境等信息监控功能于一体,对采集的信息量、采集的频率进行筛选、分析,对出现的各类问题自动报警,提高无人值守小区变规范管理与设备经济安全运行水平,提高居住区的供电可靠性。系统具有一体化、实时化、智能化、规范化的特点,克服了传统小区变运行状态无法监控,配电设备故障停电时定位困难,故障排除时间较长,客户服务质量不高的缺点。     

数控轧辊磨床砂轮选型和使用

砂轮对于轧辊磨床来说是磨削过程中尤为重要的工具,是与轧辊辊身直接接触的部件,砂轮质量的好坏、砂轮的选型和正确的使用、砂轮磨削前的修整情况及操作者对砂轮特性的熟悉程度,直接决定了轧辊的表面质量及能否满足工艺要求。因此选择砂轮主要是根据轧辊的材质、硬度及表面粗糙度的要求,对砂轮的磨料、粒度、硬度、结合剂及组织进行选择。同时根据铝加工产品要求和数控轧辊磨床特性及磨削工艺进行综合分析使用。     

SiC_p/Al超声振动辅助磨削砂轮选择方法研究

使用电镀金刚石砂轮、钎焊金刚石砂轮、陶瓷结合剂烧结金刚石砂轮和树脂结合剂烧结金刚石砂轮超声振动辅助磨削铝基碳化硅(SiC_p/Al),将砂轮磨损、材料去除、磨削表面形貌进行了对比分析,给出SiC_p/Al超声振动辅助磨削砂轮的选择方法。结果表明,陶瓷结合剂烧结金刚石砂轮在超声振动辅助磨削SiC_p/Al的过程中具有磨削过程平稳、材料去除均匀、工件表面质量好、砂轮磨损小的特点,是磨削SiC_p/Al的理想砂轮。本文的研究工作作为SiC_p/Al磨削工艺研究领域的一个方面,对SiC_p/Al磨削过程中砂轮的选择研究具有一定的指导意义。     

风电场箱变智能监控的发展及应用

具备环保、成本低、占用土地少、投资灵活等优点的风力发电是当前解决我们国家能源紧张的重要途径。风电场的地形复杂,人烟稀少,进而导致对风电场箱变的维护和监控难度加大,因此,我们必须建立有必要建立一套智能监控系统,这样既可以对风电场箱变的性能和维护进行拿面的监控,墨可以针对出现的问题也能都及时的采取相应的解决方案。     

智能工厂集中冷源监控系统设计

对工业集中冷源系统的特点及监控需求进行分析,结合PLC和触摸屏的工控优势,进行监控系统的方案设计,并成功应用于某工厂用集中冷源系统。基于该监控系统,可实现集中冷源设备的自动启停控制和恒压、恒温、变流量供水等功能,还可以对集中冷源的工况进行实时监控。     

基于DSP的低压配变监控单元的硬件设计

以DSP作为核心器件的低压配变监控单元是整套用电侧电能管理系统中的最重要的一个环节,它一般以低压网中的配电变压器(配变)为监测对象,使电力部门及时了解设备运行状况,为线损分析、负荷预测、电压合格率、配电规划等提供科学的依据。本文介绍了以数字信号处理(DSP)芯片为核心器件的低压配变监控单元的设计思路,讲述了低压配变监控单元的硬件组成和工作原理、功能。     

精细陶瓷材料的金刚石砂轮磨削性能

本文探讨了精细陶瓷材料的金刚石砂轮磨削性能的共同特点以及不同种类陶瓷和不同磨削方式的影响。研究结果表明：陶瓷材料磨削时，砂轮磨损大，磨削比小，磨削力大、磨削效率低，磨后陶瓷零件使用寿命大大降低；必须根据陶瓷种类的不同选择不同的磨削方式。     

成型砂轮廓形设计的CAD法

将作图法和计算法相结合,提出成型砂轮廓形的CAD设计方法。该方法以啮合原理为根据,采用反求设计的思路;通过做一系列垂直于砂轮轴线的截面,得到相应的砂轮与螺旋槽的接触点,连接这些接触点得到接触线,将接触线绕砂轮轴线旋转360°,即是成型砂轮的廓形。该方法具有简单直观、结果准确的特点。以球头铣刀螺旋槽的成型磨削为实例,对用CAD法设计成型砂轮的过程进行说明。该方法可用于各种按展成原理进行加工的成型工具的轮廓设计。     

Continuous generating grinding method for beveloid gears and analysis of grinding characteristics

Continuous generating grinding has become an important gear processing method owing to its high efficiency and precision. In this study, an adaptive design model is proposed for the continuous generation of beveloid gears in common gear grinding machines. Based on this model, a method for determining the installation position and grinding kinematics is developed alongside an analytical meshing model for grinding contact trace and derivation of key grinding parameters. By combining these aspects, a general mathematical model for the continuous generation of beveloid gears is presented, comprising the entire grinding process from worm wheel dressing to the evaluation of grinding deviation. The effects of the worm and dressing wheel parameters on the grinding deviation were analysed, facilitating the development of an approach to improve the grinding accuracy. The presented procedure represents a novel design method for the continuous generation of beveloid gears in common gear grinding machines, facilitating the appropriate selection of worm and dressing wheel parameters.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-022-00388-z     

New Vitrified Bond Diamond Grinding Wheel for Grinding the Cylinder of Polycrystalline Diamond Compacts

In this work, a kind of new vitrified bond based on Li2O-Al2O3-SiO2 glass ceramics was used to bond the diamond grains, which is made into grinding wheel and the cylindrical grinding process of polycrystalline diamond compacts （PDCs） by using the new vitrified bond diamond grinding wheel was discussed. Several factors which influence the properties of grinding wheel such as amount of vitrified bond and the kinds and amount of stuff in grinding wheel were also investigated. It was found that the new vitrified bond can firmly combine diamond grains, when there are only diamonds and vitrified bond in the structure of grinding wheel, the longevity of the grinding wheel is about 2.5-3 times as that of resin bond grinding wheel for processing PDCs. The grinding size precision of PDCs can be improved from 4-0.03 mm to 4-0.01 mm because of larger Young＇s modulus of vitrified bond than resin bond. The grinding time of a PDC product can be 1.75-2.0 min from 3.25-3.5 min, so this kind of grinding wheel can save much time for processing PDCs. Also, there is hardly noise when using this new vitrified bond diamond grinding wheel to process PDCs. The amount of vitrified bond in grinding wheel influences the longevity of grinding wheel. When the size of diamond grains is 90-107 μm, the optimal amount of vitrified bond in grinding wheel is 21% （wt pct）. When the amount of vitrified bond exceeds 21%, there are many pores in grinding block, which will decrease the longevity of grinding wheel. The existence of addition stuff such as Al2O3 or SiC can reduce the longevity of grinding wheel.     

立式玻璃磨边机砂轮离心振动特性分析

针对立式玻璃磨边机砂轮架的结构特点,建立其动力学模型及系统运动微分方程,导出砂轮离心力作用下砂轮架与砂轮振动的稳态响应幅值及其动力放大因子β1、β2的理论计算公式,着重分析砂轮离心力激振下砂轮架及砂轮的振动特性及规律,结果表明：β1、β2的大小和砂轮与砂轮架的质量之比µ、固有频率之比α,砂轮角频率与固有频率之比λ,阻尼比ξ等因素有关;合理选择µ、α、ξ值,可使砂轮与砂轮架具有相同且较小的动力放大因子;避免砂轮工作在λ=0.9~1.1对应的转速范围内,可有效减轻砂轮架及砂轮的振动程度。研究结果突破了现有研究将砂轮轴刚性化处理、试验测试装备复杂等缺陷,具有物理概念清晰、计算简单等特点。     

成形磨砂轮圆弧廓形关键参数在位检测方法及试验研究

针对成形磨砂轮精密磨削加工中准确高效地检测砂轮形状精度的需求,提出砂轮廓形参数在位检测新方法。首先采用线状激光位移传感器采集砂轮表面微观形貌数据,构建测量矩阵模型,再通过滤波去噪、宏观轮廓线提取、非线性曲线拟合等算法分析处理出砂轮廓形曲率半径和圆度误差检测指标。通过磨削验证试验分析和检测不确定度评定,证明该方法稳定可靠,检测结果可以准确反映工件加工精度,满足复杂圆弧廓形砂轮检测需求,具有较好的工程应用价值。     

工程陶瓷高效平面磨削表面波纹度试验研究

 以氧化铝和氧化锆两种工程陶瓷在高效磨削条件下的磨削振动和表面波纹度为研究对象,概述了磨削表面波纹度的定义和评价方法以及产生波纹度的原因,在超高速平面磨削实验台上进行磨削工艺试验,通过改变砂轮线速度、进给速度和磨削深度,分析了磨削参数对零件表面波纹度的影响。在试验研究的基础上,对磨削表面波纹度的影响因素和机理进行分析和讨论。试验结果表明,在陶瓷材料高效平面磨削中,砂轮线速度和进给速度是影响磨削颤振与表面波纹度的主导因素。在如120 m/s的较高砂轮线速度时,磨削过程振动主要是由强迫振动引起,工件表面质量好于低速情况。在保证较高磨削效率的前提下,陶瓷材料的高效磨削更适合在大切深和小进给速度条件下进行。     

Controlled wear of vitrified abrasive materials for precision grinding applications

The study of bonding hard materials such as aluminium oxide and cubic boron nitride (cBN) and the nature of interfacial cohesion between these materials and glass is very important from the perspective of high precision grinding. Vitrified grinding wheels are typically used to remove large volumes of metal and to produce components with very high tolerances. It is expected that the same grinding wheel is used for both rough and finish machining operations. Therefore, the grinding wheel, and in particular its bonding system, is expected to react differently to a variety of machining operations. In order to maintain the integrity of the grinding wheel, the bonding system that is used to hold abrasive grains in place reacts differently to forces that are placed on individual bonding bridges. This paper examines the role of vitrification heat treatment on the development of strength between abrasive grains and bonding bridges, and the nature of fracture and wear in vitrified grinding wheels that are used for precision grinding applications.     

Study into grinding force in back grinding of wafer with outer rim

Back grinding of wafer with outer rim (BGWOR) is a new method for carrier-less thinning of silicon wafers. At present, the effects of process parameters on the grinding force remain debatable. Therefore, a BGWOR normal grinding force model based on grain depth-of-cut was established, and the relationship between grinding parameters (wheel infeed rate, wheel rotational speed, and chuck rotational speed) and normal grinding force was discussed. Further, a series of experiments were performed to verify the BGWOR normal grinding force model. This study proves that the BGWOR normal grinding force is related to the rotational direction of the wheel and chuck, and the effect of grinding mark density on the BGWOR normal grinding force cannot be ignored. Moreover, this study provides methods for reducing the grinding force and optimizing the back thinning process of the silicon wafer.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-020-00316-z