精密主轴回转误差测试的偏心分析

对精密主轴回转误差测试过程中偏心的影响和作用原理进行了深入分析,指出了消除偏心时的一些误区,提出了合适的偏心消除方法,设计了螺钉调整和敲击调整两种偏心调整装置,实验证明敲击调整方案更具操作性和实用性,可使偏心稳定调整到0.5μm以下,对提高精密主轴回转误差的测试精度具有一定意义.     

一种气浮主轴径向回转误差的测量方法

详细论述了双传感器转位法测量气浮主轴径向回转误差的基本原理,该方法能有效地分离出主轴的回转误差和标准钢球的圆度误差,通过消除一次谐波来去除安装偏心。并且设计了回转误差的测试系统,该系统能满足测量的要求。     

车床主轴回转精度数字式单向测量法北大核心

车床主轴回转精度的测量是一项重要的测试课题。针对传统的测量方法需要使用基圆发生器,数据处理困难,测试结果难以在各车床间进行比较等问题,提出了利用数字式单向测量法对车床主轴回转误差进行动态测量。从分析回转误差的测试原理和误差性质出发,建立起回转误差的数学模型,利用信号分析的手段分离出基准球安装偏心误差,并通过计算机仿真对该数学模型及分离方法进行验证和分析。实验结果表明,采用本文的方法对C616主轴回转精度进行测量,其测量结果与DJ-HZ-1型机床回转精度测量分析仪的测量结果基本吻合。     

精密球面磨床主轴回转误差的高精度测量

利用主轴回转误差单点测量法设计了一套测量系统,该系统由高精度标准球、高精度非接触位移传感器和角度传感器组成.阐述了回转误差的测量原理,分析了测量过程中可能引入的测量误差及其消除方法,并进行了实验研究.通过测量系统对测量数据进行了自动获取和分析处理,并用最小二乘法对测量数据进行评定,实现了精密球面磨床主轴回转误差的高精度测量.     

主轴回转精度测试方法研究

回转精度是衡量超精密主轴的关键技术指标。传统的回转精度测试方法存在不足,如单点法和2点法不能实现误差分离;多步法需要进行多次精确转位,不利于在线测量;传统3点法可实现误差分离,但存在原理误差,不能分离主轴回转误差中的一次成分等。文中提出了一种工程测试3点法,该方法采用3个传感器在被测件上严格定点采样;利用3点法圆度误差分离技术分离出被测件圆度误差,利用2点法偏心误差分离技术分离出测试系统偏心误差;从实时采样数据中剔除被测件圆度误差及偏心误差,实现主轴回转误差在线测量及状态监测。揭示了单周采样点数、传感器安装角、偏心误差、传感器误差及角位置误差等因素对3点法测试精度的影响规律,对工程测试3点法的参数选择及形状失真进行了综合分析和优化。试验结果表明:文中所提方法有效。     

主轴顶尖偏心调整机构在数控滚齿机上的应用

数控滚齿机床上误差总是不可避免地存在,特别是数控机床主轴的回转误差更是由多种因素引起的,它的存在将直接影响被加工对象或被测量对象的精度.为此,将自由调节回转偏心的顶尖应用于数控滚齿机上,即使其主轴存在偏心,通过调整此机构,也可使顶尖轴线和回转轴线的回转偏心接近于零.     

数控车床主轴热变形检测及回转精度评定

针对主轴回转热误差包含的多种误差分量,采用双向正交法测量了不同转速温度场下数控车床主轴热变形所引起的回转误差。以复向量描述主轴回转精度理论为基础,利用FFT误差分离方法,从传感器测得的信号中分离并去除检棒的安装偏心及热变形导致的回转中心的偏移量,从而得到精确的主轴回转热误差信息,进而评定数控机床主轴热变形对加工精度的影响。     

Y9025型圆度仪测量钢球圆度时的调偏心方法

甲Y0025型圆度仪测量套圈和钢球圆度时,具重要步骤是调整被测工件截面中心与圆度仪主轴回转中心同心,因为工件与主轴偏心大小直接影响到圆度误差读数的准确性,偏心越小,测值才能越接近真值。用该仪器测量套圈圆度时,可以直接使用仪器上的调心装置,较方便地调整工件与主轴的偏心。但在测量钢球圆度时,调心装置不好用,过去一贯使用电感比较仪进行手工调整,不仅费时费力,而且调整效果不够理想。为了解决这一问题,我们摸索出借助于仪器传动和测量显示系统调整钢球偏心的方法,既提高了工作效率,又有效地控制了偏心量。     

主轴回转精度测试中测量球的残留偏心对测量结果的影响

在主轴回转精度的测试中,有时要求测量球应调整得与主轴中心线愈准确愈好,否则会因残留偏心引起圆图象心形畸变,对测试结果带来误差。本文讨论残留偏心对测试结果影响的程度。     

高速主轴回转误差动态测试与分析

应用双向法设计测试系统,对主轴的回转误差进行动态测试.该系统由高精度标准棒、非接触位移传感器和LMS TEST,LAB采集器组成.阐述了回转误差的测试原理,针对机床主轴测试中标准棒的安装偏心问题,提出了有效解决方法,并进行了实验研究.     

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.