螺纹测量的解决方案

随着装备制造业的发展以及螺纹零件加工精度和检验标准的提高,传统的测量方式越来越难以满足精密螺纹的测量需求。螺纹测量的解决方案是利用精密测量仪器一次性完成螺纹大径、小径、中径、螺距以及牙型角等项目的测量,不仅能够满足在线测量、智能测量以及测量结果统计等需求,还以其高精度、高效率和低误差等优点在螺纹测量中发挥重要作用。     

中径及单一中径与螺纹加工径向误差

本文通过用车刀车削螺纹时刀具径向位置与完工螺纹中径及单一中径之间的对应关系,说明中径误差不是单纯的径向误差,中径误差应是加工时径向误差与轴向误差综合作用的结果。而单一中径误差能确切地反映车削螺纹时的径向误差。1981年我国颁布的螺纹术语标准［’冲,不仅有中径术语,还出现了单一中径术语。对圆柱螺纹而言,它们的定义分别为：中径：一个假想圆柱的直径,该圆柱的母线通过牙型上沟槽和凸起宽度相等的部位。该假想圆柱称为中径圆柱（图略）。单一中径：一个假想圆柱的直径,该圆柱的母线通过牙型上沟槽宽度等于1／2基本螺距的…     

螺纹千分尺的正确选用及测量误差

在大批量生产中螺纹零件通常用螺纹量规进行检测,而在小批量和单件加工中则普遍使用万能量具检测。螺纹中径的测量,属于螺纹基本要素的检验项目。其检验方法应理解为确定螺旋副旋合条件的中径、螺距和牙型角各项。本文不对螺距、牙型角的测量进行讨论,仅对螺纹中径的测量进行讨论。     

螺纹单一中径与螺纹中径的区别

1在定义上，对圆柱螺纹而言，单一中径与中径的区别单一中径的定义为：一个假想圆柱的直径，该圆柱的母线通过牙型上沟槽宽度等于基本螺距一半的地方。中径的定义为：一个假想圆柱的直径，该圆柱的母线通过牙型上沟槽和凸起宽度相等的地方。2在加工误差原因上，单一中径与中径的区别对用车刀车削螺纹而言，引起单一中径尺寸误差的主要原因，是加工时刀具径向对刀尺寸的调整误差，而加工时轴向送进量的误差。对单一中径的大小没有影响。对用车刀车削螺纹而言，引起中径尺寸误差的原因，既与刀具径向对刀尺寸的调整误差有关．也与加工时轴向送…     

用坐标法测量螺纹量规的中径及误差分析

通过测量任意相邻三个牙型上的三点获得螺纹量规中径的方法,符合GB／T14791－93《螺纹术语》中的中径定义,不存在明显误差,操作过程简便。误差分析表明,螺距误差、牙型半角误差对中径测量及单一中径测量没有影响。     

螺纹中径测量中fp与f a／2的正确计算

螺纹中径是衡量螺纹互换性的重要指标。螺纹螺距误差与牙型半角误差中径当量的计算对于判断螺纹中径合格性至关重要。本文给出螺距误差和牙型半角误差中径当量的计算式,对于正确贯彻螺纹标准和得到准确的螺纹中径值有一定参考价值。 由于螺纹公差标准对螺纹顶径、中径和底径的公差作了规定,所以螺纹中径尺寸就成了衡量螺纹互换     

普通螺纹中径光学测量的新方法

介绍了测量任意相邻３个芽型上的３点获得螺纹中径和单一中径的方法。该方法符合ＧＢ２５１５－８１定义，不存在原理误差。     

螺纹量规中径光学测量的“坐标点”方法

文章提出的“坐标法”测量螺纹量规中径的方法 ,符合 GB/T1 4791 - 93螺纹中径的定义 ,不存在原理误差。螺纹牙型半角误差及螺距误差对中径测量不产生影响。中径测量结果与三针法量值的可比性较好。在国产 JX1 3B微机型万能工具显微镜上用影像法、轴切法或干涉法测量时 ,可以直接显示测量数据和打印测量结果。     

普通螺纹牙侧角误差对螺纹结合互换性的影响

介绍了与普通螺纹有关的基本术语，针对螺纹牙型半角误差常被作为衡量螺纹牙型角度误差对其互换性的影响参数的实际状况，提出牙侧角误差(非牙型半角误差)才是真正影响螺纹的作用中径从而影响螺纹结合互换性的参数，并从理论上进行了分析与推导。     

螺纹中径测量中fp与fα／2的正确计算

螺纹中征是衡量螺纹互换性的重要指标。而螺纹螺距误差与牙形半角误差中径当量的计算对于判断螺纹中经合格性至关重要。本文给出了螺距误差和牙形毕角误差中经当量的计算式，对于正确贯彻螺纹标准和得到准确的螺纹中径值有一定参考价值。由于螺纹公差标准对螺纹顶径、中径和底径的公差作了规定，所以，螺纹中径尺寸就成了衡量螺纹互换性的重要指标。这一点由螺纹其它几何要素（螺距、牙形半角）的误差均在螺纹中径上有反映可以得到证明．这样螺距误差与牙形半角误差都和中径相关，可以通过几何关系折算到中径上，该拆算值分别称为螺距误差中…     

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...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

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.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

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...