谈谈瑞士精密机床(二)

三、斯图德磨床1.斯图德磨床的特点斯图德(Studer)厂以制造高精度外圆磨床闻名于世,它生产的RHU系列液压万能外圆磨床的保证精度如下:不圆度③:标准精度 0.4μm提高精度(两种) 0.2μm;0.1μm不直度:(最大磨削长度)     

中心孔磨削方法

一、中心孔磨削和外圆磨削精度 在轴类零件的磨削加工中,一般都以中心孔作基准。因此,工件中心孔的精度是影响外圆加工精度的重要的因素。通常用中心钻加工出来的中心孔其不圆度是 50～180μm。而用这样的中心孔作基准进行外圆磨削时,得到的外圆的不圆度一般在 2～3μm。 但是,如果对工件中心孔进行磨削加工,提高其不圆度精度,然后再以它为基准来磨削工件外圆时就能得到 0.2μm的外圆不圆度精度。 表1是对5个试件进行试验磨削的结果。由表1可见,用车床加工出的中心孔,其不圆度在 8～10μm。中心孔经过磨削后,其不圆度大约可减少到 1/2。由于…     

主轴部件套类零件高精度立式磨床研制

在分析套类工件结构特点和技术要求基础上,以精度为目标,开展了立式复合磨削工艺路线设计及与之相适应的精密立式磨床研制。所研制的磨床其动态回转精度优于0.3μm的高刚度液体静压直驱式静压回转工作台和运动直线度优于0.2μm/200 mm的高刚度液体静压导轨很好地保证工件磨削圆度和母线直线度。研制的机床实现了内孔磨削圆度0.7μm,外圆磨削圆度优于0.45μm的磨削效果,能满足各种高精度主轴部件套类零件高精度磨削。     

基于电压影响下圆偏振激光束的特性

采用狭缝光束分析仪和偏振仪测量了从铝薄膜表面反射的圆偏振光的光斑位置和偏振特性随外界直流电压变化情况,理论拟合激光从铝薄膜反射后的光斑位置与直流电流电压的关系。测量和多项式拟合结果表明,当外部电压值从0变化到2.5V时,圆偏振激光在x轴和y轴上的位置分别是从-45μm移动到-95μm,从35μm移动到75μm,而激光束的光学偏振度基本上不变化。     

入射激光对激光扫描共聚焦显微镜分辨率的影响

利用点扩散函数(PSF)研究了入射激光的偏振态和光束的束腰直径对激光扫描共聚焦显微镜(LSCM)分辨率的影响。根据Wolf和Richards的矢量衍射积分,建立了LSCM N-1层界面下的照明PSF模型,对零层和两层界面下的PSF进行了计算分析。结果显示:在零层界面下,圆偏振光入射的PSF在xy平面内关于焦点旋转对称,半峰全宽为0.43μm,x向线偏振光入射时PSF在x、y方向的半峰全宽分别为0.48,0.39μm;在圆偏振光入射的PSF中,高斯光束充溢系数为0,1,2,5对应的半峰全宽分别为0.43,0.47,0.62,1.49μm。在两层界面下,当探测深度为50μm时,圆偏振光PSF的半峰全宽为0.26μm,x向线偏振光入射时PSF在x、y方向的半峰全宽分别为0.28,0.24μm;在圆偏振光入射的PSF中,充溢系数为0,1,2,5对应的半峰全宽分别为0.26,0.28,0.32,0.68μm。以上计算结果表明,和线偏振光相比,圆偏振光在一个方向的分辨率优于线偏振光,在相垂直的另一个方向的分辨率弱于线偏振光,圆偏振光PSF在xy平面内关于焦点旋转对称,得到了较好的成像质量;物镜入瞳直径与激光束腰直径比值越小,LSCM的分辨率越好。     

基于电压影响下圆偏振激光束的特性（英文）

采用狭缝光束分析仪和偏振仪测量了从铝薄膜表面反射的圆偏振光的光斑位置和偏振特性随外界直流电压变化情况,理论拟合激光从铝薄膜反射后的光斑位置与直流电流电压的关系。测量和多项式拟合结果表明,当外部电压值从0变化到2.5V时,圆偏振激光在x轴和y轴上的位置分别是从-45μm移动到-95μm,从35μm移动到75μm,而激光束的光学偏振度基本上不变化。     

第五讲 高光洁度高精度磨削

高光洁度磨削可以获得10～14表面光洁度;不圆度可达0.1μm;不柱度1μm/300mm;不同轴度小于1μm;平面工件的不直度小于3μm/1000mm。可适用于内圆、外圆、平面和无心磨削等工序。根据加工的光洁度不同,划分为精密磨削、超精磨削和镜面磨削。通常把光洁度10～11称为精密磨削,它适于液压件的阀类零件、机床主轴、     

超精密主轴的钢球顶磨法

在中心磨床上磨削主轴通常使用60°顶尖进行定位,尽管对工件中心孔经过磨削或研磨,但其磨削所得的圆度精度一般只能达到1,5～0.8μm。这是由于轴两端的中心孔及磨床头尾架顶尖之间存在同轴度误差,顶尖与中心孔之间成点状接触(见图1),这种点状接触在中心孔和顶尖锥面的圆度误差以及磨削过程中磨制力变化等因素的影响,而发生位置变化,产生磨削误差,影响磨削表面的圆度等精度。 我们在无心磨床主轴的轴颈磨削中使用钢球代替顶尖,取得了较为理想的圆度精度。工件要求φ90mm轴颈外圆的圆度误差小于0.5μm,实际磨削达到 0.4μm以内。 用钢球定位顶…     

提高外圆磨床磨削圆度工艺的探讨

机床主轴圆度的好坏将直接影响机床的质量.但在生产中,要使一般精度的外圆磨床,如M1432A,能加工出圆度小于0.5μm的主轴是一件十分困难的事. 最近,我们在M1432A×1000mm外圆磨床上,在机床精度不作任何调整的情况下,对工件圆度的磨削作了一系列工艺试验.结果磨出的试件圆度最好达0.2μ,最差为0.3μm,效果很理想.现将试验情况介绍于下: 一、影响工件圆度的因素 1.拨叉回转半径对圆度的影响以往磨削外圆一般是在头尾架上装上硬质合金死顶尖顶住工件中心孔,用鸡心夹头夹住工件,由头架     

三点法圆外径测量优化研究

为提高三点法圆外径测量方法精度,解决接触式测量精度低和易损伤工件等问题,文中进行了非接触式三点法圆外径测量优化研究。该研究对传感器布放角度进行优化设计,建立考虑传感器安装偏角误差的三点法圆外径测量的数学模型,直接使用解析的方法进行半径求解,避免了傅里叶变换所带来传递函数分母为零的频域特征损失。在此理论研究基础上,搭建了基于电容位移传感器的非接触式三点法圆外径测量装置。使用三坐标测量机建立标定坐标系,拟合测量出3支电容位移传感器的安装偏角,完成三点法圆外径测量装置的参数标定和误差修正。标定完成后应用该测量装置对已知外圆半径为18 mm的标准工件进行测量,6组不同位置的测量结果表明,未考虑传感器安装偏角误差时圆半径测量的最大偏差为19.6μm,标准差为11.9μm,修正传感器安装偏角误差后圆半径测量的最大偏差为3.3μm,标准差为2.2μm,优化的测量方法标准差显著减小,验证了方法的有效性。     

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.     

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....     

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。     

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.