液压膨胀夹头的径向刚度分析

液压膨胀式夹头刀柄是一种采用液压膨胀原理夹持刀具的超高精度刀具夹头,夹头的径向夹持刚度对加工零件的表面质量以及夹头刀具的整体震动都有着非常重要的影响。为了充分发挥液压膨胀夹头刀柄在高速加工中的应用潜能和效用,利用有限元分析法对静压膨胀夹头的径向夹持刚度影响因素进行了分析。分析了夹头-刀具的配合间隙、油腔凸起长度、油压以及转速对夹头径向夹持刚度的影响,研究结果对于夹头的生产制造和合理控制加工质量提供有效的依据和参考。     

高速HSK液压夹头及工具系统的不平衡响应

高速夹头是高速加工工具系统的重要组成部分,其性能直接影响高档数控机床的性能及加工质量。利用有限元分析法,分析不平衡量产生的惯性离心力对带有液压夹头的HSK工具系统动态性能的影响,系统地揭示了刀柄节点、夹头节点和刀尖节点位移的变化规律:随着激振频率的升高,工具系统刀尖、夹头和刀柄位移响应幅值逐步增大;随着不平衡量增大,刀尖、夹头和刀柄动态位移响应幅值呈线性增长,为HSK液压夹头及工具系统的优化设计和其动平衡的控制提供了理论依据。     

高速切削中的几例刀具夹头

高速切削加工除了对刀具有相应的要求外，对刀具夹持系统也有很高的要求。本文分析、介绍了适用于高速加工的静压膨胀式刀具夹头、三棱变形夹头、热缩夹头和高精度弹簧夹头的工作原理及典型产品。     

高速加工用夹头的主要特征及选用

随着高速加工技术的发展,对高速刀具的夹紧提出了新的技术要求。本文对高速夹头的综合性能作了系统的对比分析,整理出各种高速夹头的特性及主要应用范围,为科学合理地选用夹头提供了理论依据。     

一种新的刀具圆弧过渡补偿算法

高速铣削加工中圆弧过渡刀具补偿方法具有补偿曲线平滑、速度冲击小、加工表面质量好等优点。通过建立刀具补偿数学模型，根据理论加工曲线衔接点处切线矢量转角的区间分布特征，给出且证明了圆弧过渡刀具补偿类型的判据公式，并依据此判据公式实现了圆弧过渡刀具补偿算法。实践表明，该算法形式统一，适用于直线、二次曲线、NURBS曲线以及其他高阶样条曲线的刀具加工路径的刀具半径补偿运算，且计算量小、易于实现。     

整体叶盘叶片铣削加工表面质量控制仿真研究

以整体叶盘叶片为研究对象,建立了叶片铣削加工三维有限元仿真模型,运用动态仿真分析方法,结合数控仿真加工无干涉刀具轨迹,分析研究了叶片表面残余应力分布情况及铣削参数对叶片加工表面质量的影响规律。分析结果表明:叶片表面应力分布均匀,只在两缘区域出现应力集中现象;叶片两缘区域表面残留高度值大于中轴区域;相同切削条件下,提高主轴转速和减小每齿进给量均有利于改善叶片加工表面粗糙度。该结果对后续优化叶片加工参数的研究及叶片加工表面质量的提高具有重要指导意义。     

柴油机进气门颈部特征分析与结构优化

气门的颈部是杆部与盘部的过渡区域,也是应力集中的区域,结构不合理导致应力集中程度严重,促进疲劳源的产生,是疲劳断裂的主要原因之一。本文从优化气门颈部结构入手,利用有限元软件Abaqus对气门进行了热-应力耦合分析,对颈部应力集中程度和颈部结构对应力分布的影响进行了探究。利用SolidWorks对进气门的过渡锥角β和过渡圆弧半径R在允许范围内进行调整,再把新的模型导入到Abaqus进行分析,以最大应力最小,应力分布均匀为目标进行优化,研究了β和R对最大应力及应力分布的影响。由此得出：β=21°,R=21mm为最优结构,即过渡锥角为21°,过渡圆角半径为21mm。     

液压膨胀夹头的夹紧疲劳可靠性分析

针对液压膨胀夹头在使用过程中局部出现裂纹现象,通过有限元理论和疲劳分析理论相结合进行了液压膨胀夹头的夹紧疲劳可靠性分析。在夹头静力学分析的基础上定义了液压膨胀夹头的疲劳破坏载荷谱和材料的疲劳特性曲线,采用ANSYS软件中的Ncode疲劳分析模块计算了液压膨胀夹头的疲劳寿命和疲劳损伤,并且确定了夹头最易发生疲劳损伤的区域,最后通过实验验证了仿真的结果,研究结果为夹头的结构优化设计和夹头的实际使用提供有效的依据和参考。     

山特维克可乐满的高精度液压夹头CoroChuck 930

山特维克可乐满推出的CoroChuck 930高精度液压夹头为铣削和钻削工序带来了安全的刀具性能.它完美地满足了高跳动精度的苛刻要求,大量的测试表明,这种新的液压夹头能够提供最佳的抗拔出安全性. 在夹持孔两端采用了铜膜的优化设计,确保了最大的安全夹紧(支点),这也是CoroChuck 930高精度和抗拔出能力背后的秘诀.这些特性确保了优良的扭矩传递性能,从而提高了整体硬质合金立铣刀、钻头和铰刀的加工性能.这种改善的性能确保了夹头寿命,使多次装夹仍然保证高精度,这也确保了高表面质量零件加工并延长了刀具寿命.另外,CoroChuck 930设计有减振功能,在加工期间能够使振动最小化.     

采用静压膨胀原理的精密刀具夹头

静压膨胀式刀具夹头是一种采用静压膨胀原理夹持刀具的超高精度刀具夹头。分析、介绍了静压膨胀式刀具夹头的结构原理、技术性能和使用要求。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.