浅谈共轭凸轮加工方法

一、普通仿形磨削存在的问题我厂在加工共轭凸轮时,过去采用普通仿形磨削法,即分别用外轮廓线靠模和内轮廓线靠模仿形磨削凸轮的内外轮廓线。所加工出的凸轮共轭精度误差为0.15mm,同名凸轮同步精度误差为0.12mm。误差较大的原因主要是由于: 1.凸轮的内外轮廓线之间存在着较大的位置误差。这种误差可通过配位角(凸轮上定位孔的基线OD与确定凸轮上传动函数零点的直线之间的夹角;见图     

无接触仿形控制原理的研究

一、无接触仿形的提出无接触仿形是在光电跟踪实践的基础上提出来的。前者跟踪样板,后者跟踪图线。由于图线的绘制误差较大,使产品的尺寸精度受到影响。故提出直接对样板进行仿形。样板既是加工依据也是检验依据。此外,这种仿形还适用于模具制造,可利用阳模来仿制阴模。目前,为了解决曲线加工,除用数控外,还可用液压仿形,但光电仿形与前两者比较,有它的优点:     

夹江水工机械厂生产出我国最大的船闸反弧门

我国最大的船闸反弧门———三峡三程永久船闸输水廊道第 6闸首第一套反弧门在近日通过验收。这套由夹江水工机械厂生产制造的反弧门重 80余吨 ,门宽 4 4 7ｍ ,高 5 99ｍ ,面板圆弧半径 8 2ｍ ,是三峡工程永久船闸通航的重要设备。反弧门作为永输水廊道的工作阀门在每级闸首左右对称布置 ,共 2 4套。这种类型的弧门面板采用不锈钢复合板 ,面板与支臂连成一体 ,门体止水部位、支铰孔等多处部位均为要求极高的整体加工。为保证良好的止水效果 ,底止水采用硬止水方式 ,加工后直线度不得大于 0 1ｍｍ。由三峡总公司设备部、技术部、航建项目部…     

机床部件非均匀接触对系统精度稳定性影响研究现状

针对机床结合部非均匀接触对系统精度时变特性的影响问题,文章综述了机床运动副和紧固部件结合部的几何特征误差引起的非均匀接触特性对系统精度稳定性影响的研究现状,主要体现在运动副部件形位误差造成运动过程滚动体接触部位处于非均匀接触时变状态、紧固结合面的加工形位误差和粗糙度特征的切向非均匀分布及其法向误差幅值的非均匀变动、刮研结合面呈现的非均匀接触点误差特征;并且这些接触部位在部件非对称力矩、非均匀预紧力、振动、温度、运动形式等变动因素作用下,呈现结合部形位的非均匀非线性变化特点,成为影响精密机械系统精度稳定性关键因素,并导致了机床精度的复杂非线性时变特性,造成结合部对机床精度变动产生机理的研究困难;因此,需要重点突破机床结合部的几何特征误差曲面建模、形位非线性变动预测和几何特征误差对机床精度时变特性预测等关键技术,深入研究机床结合部的非均匀应力场的形成与表征、结合部的非均匀温度场建模及变动特性研究、力热作用的结合部摩擦时变特性,揭示结合部几何误差特征造成的机床精度时变机理,增进机床精度稳定性优化设计和精度稳定性技术体系。     

液体火箭发动机U形环密封界面优化设计

U形密封环是液体火箭发动机常用的一种密封结构,其密封性能是决定发动机可靠性的关键因素。为研究U形环的密封机制,改善其整体结构的密封性能,构建U形环密封结构的有限元分析模型,分析常温预紧工况和低温工作工况下密封环的密封性能。结果表明：相对于常温（20 ℃）预紧工况,低温（-183 ℃）工作工况下U形环密封面的有效接触宽度和接触应力更大,但仍存在密封面接触不充分的问题。采用密封界面形貌的优化设计方法对U形环密封界面进行优化设计,优化后U形环密封面从平坦形貌变为非平坦的非线性形貌,低温工作工况下U形环密封面的有效接触宽度增加了138%,接触应力分布均匀程度提升了99%,密封面的有效接触宽度大幅增加,接触应力分布的均匀性大幅改善,整体结构的密封性能显著提升。     

用新工艺改造W-125仿形龙门铣

W-125摇连杆仿型铣床能耗高，精度低，设备故障多，功效低。对其驱动系统采用三菱A500数字变频器改造，并用新的工艺对机械部分进行修理，性能达到国内同类机床的先进水平，延长了设备使用寿命，缓解了企业购置设备的资金压力，且设备节能效果显著。就此对W-125仿形龙门铣驱动系统的变频改造，机床导轨TSF软带修复，设备修理改造后的节能效果作一简介。     

液压仿形车床随动阀的修复

液压仿形车床随动阀的修复长城机床厂张同波关键词随动阀，修复，仿形车床液压仿形车床的随动系统经过长期使用，均有不同程度的磨损，导致车床加工误差增大、工作稳定性变差和灵敏度降低等现象。因此，根据具体情况需及时修复系统中的核心元件随动阀。下面以我厂生产的Ｃ...     

高精度非线性凸轮曲线的加工研究

介绍了一种特殊的仿形加工高精度非线性凸轮曲线的方法。详细叙述了加工原理、结构和精度分析以及测量方法和结果。最大加工误差不超过0 .0 2 mm。     

单座标液压随动仿形铣床

我厂生产图1所示的刹车凸轮,过去是在一台机械仿形铣床上加工的。该铣床结构复杂,零部件容易磨损,加工精度难以保证。为解决这一问题,我们把本厂一台二号普通立式铣床改装成单座标液压随动价形铣床,用来加工凸轮,仿形误差 0.03 mm,重复精度达 0.02 mm。这台机床自 80年使用以来     

基于Pro/E软件的仿形靠模轮廓曲线设计与运动仿真

设计仿形靠模轮廓曲线常用方法有作图法与计算法。计算法过程烦琐,需要计算机辅助编程完成,而传统作图法又具有误差大、精度不高的问题。以某一生产零件为例,利用Pro/E软件将作图法融入其中获得仿形靠模理论轮廓曲线的坐标,并生成较高精度的仿形靠模理论轮廓曲线及其实体,提高了仿形靠模的设计精度与效率。实践证明,这是一种有效的方法。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.