弧齿锥齿轮双重螺旋法切齿原理及齿面接触分析研究

弧齿锥齿轮双重螺旋法具有高效、可实现干切削的特点,是Gleason制弧齿锥齿轮的先进加工方法。为揭示双重螺旋法的切齿原理,以大轮成形法加工的弧齿锥齿轮双重螺旋法为研究对象,以啮合原理和微分几何学为基础,根据刀盘、机床、工件之间的运动位置关系,利用矢量法、基于齿面3个参考点建立切齿数学模型,推导机床调整参数的计算过程;然后,以齿槽中点作为参考点,修正弧齿锥齿轮副的齿坯几何参数;另外,以小轮产形面方程代替其共轭齿面方程,提出新的齿面失配设计新方法,与传统方法相比简化计算过程。以一对7×43的准双曲面齿轮副为例进行设计计算和切齿加工,齿面接触分析与滚动检查结果验证所提出的双重螺旋法切齿原理的正确性,并根据该切齿原理开发弧齿锥齿轮双重螺旋法的设计软件,为该方法在国内的推广提供理论基础与技术支撑。     

渐开线弧齿圆柱齿轮及其啮合特性

阐明了渐开线弧齿圆柱齿轮的主要几何参数，利用微分几何理论推导出渐开线弧齿圆柱齿轮的齿面方程、共轭齿面方程以及齿轮副的啮合线、齿面接触线表达式，并通过计算机编程对弧齿圆柱齿轮的齿面、共轭齿面、啮合线及齿面接触线实现图形绘制，直观地揭示了弧齿圆柱齿轮在传动过程中的啮合特性。渐开线弧齿圆柱齿轮具有较长的齿面接触线和较大的啮合重合度，齿轮副啮合平稳性好。     

螺旋齿面齿轮两自由度车齿原理研究

针对现有齿轮加工方法不能加工较大螺旋角的螺旋齿面齿轮问题,提出了一种螺旋齿面齿轮的车齿加工方法。根据空间交错轴啮合原理,建立螺旋齿面齿轮两自由度车齿的理论加工模型,研究车齿刀、假想螺旋产形齿轮和螺旋齿面齿轮的安装布置关系,分析面齿轮车齿中的自由度,建立车齿中刀具和面齿轮的展成运动模型。以直齿渐开线作为刀具的切削刃形,运用微分几何与啮合原理,推导车齿加工的啮合方程、螺旋齿面齿轮的工作齿面方程以及过渡齿面方程,并建立了螺旋齿面齿轮的车齿齿面与理论齿面的误差分析模型。仿真表明：凸齿面离散点误差为-0.01～-0.02mm,凹齿面离散点误差接近0,从而验证螺旋齿面齿轮两自由度车齿加工原理的可行性。     

曲面综合法少齿数弧齿锥齿轮加工参数计算仿真与切齿试验

少齿数高减比齿轮传动具有体积小和轻量化的优势。根据综合变位和节锥外啮合原理,设计了一对高减速比弧线等高齿锥齿轮,给出了相关的几何限制条件,推导了大、小轮齿面方程。大轮采用成形法加工,小轮采用单面展成法加工,为弥补大轮齿廓曲率的不足,小轮刀齿采用圆弧刃修形,采用曲面综合法优化求解了小轮加工参数;通过建立ease-off差齿面,对齿面修形梯度、传动误差、接触路径与接触线进行了仿真。切齿和滚检试验,验证了高减比弧齿锥齿轮几何设计、刀盘修形加工方法的可行性。     

分阶式双渐开线齿轮啮合特性及有限元研究

利用空间啮合原理,建立分阶式双渐开线齿轮型线齿廓理论与数学模型,推导双渐开线齿轮端面齿廓方程和接触线方程,对相互啮合的两个双渐开线齿轮端面啮合过程及接触线变化进行模拟分析,基于ANSYS有限元分析软件,利用其中的参数化设计语言APDL,精确建立双渐开线齿轮的单齿啮合和双齿啮合有限元模型,并对其进行接触有限元分析.分析结果表明,节点附近啮合时,双渐开线齿轮接触线发生间断,并且单齿啮合远大于双齿啮合的齿面最大接触应力.     

基于产形齿条端面齿廓的相交轴渐开线变厚斜齿轮建模

根据渐开线齿廓变厚斜齿轮的齿形特征,以斜齿产形齿条为假想加工刀具,建立其端面齿廓参数方程;基于空间啮合原理,推导产形齿条与渐开线齿廓变厚斜齿轮的啮合方程及齿面方程;利用Imageware和UG三维建模软件建立渐开线变厚斜齿轮的实体模型。从产形齿条端面齿廓方程入手推导啮合关系使变厚齿轮的建模思路更为清晰直观,为该类齿形较为特殊的齿轮模型建立提供了新的思路。     

克林贝格摆线齿锥齿轮齿面方程及图形仿真

介绍了平面产形轮及其延伸外摆线齿形的形成过程,根据铣齿过程中刀盘、产形轮和被加工轮坯的相对位置和运动关系,建立了切齿啮合坐标系,推导了产形轮的齿面方程;利用切齿啮合关系和空间啮合原理推导了摆线齿锥齿轮的齿面方程,并用计算机绘制了产形轮和锥齿轮齿面的三维图形。     

螺旋运动及刀具参数对双重螺旋法加工齿面特征的影响规律

双重螺旋法具有高效率、低成本、可干切削等特点是取代"五刀法"的弧齿锥齿轮未来主流加工方法。为了揭示弧齿锥齿轮双重螺旋法的切齿原理,在分析五刀法切齿原理的基础上,研究了刀倾角和齿形角分别在五刀法和双重螺旋法中的不同作用原理,揭示了双重螺旋法切齿原理的本质;分析了螺旋运动在切齿加工中的作用及对齿面几何形貌的影响规律,推导了小轮齿面参考点处的曲率参数计算公式,揭示了螺旋运动系数与参考处曲率的关联规律,并利用轮齿接触分析方法研究了螺旋运动对齿轮副啮合性能的影响规律;利用数值方法研究了刀具齿形角、刀盘半径分别对轮齿接触椭圆长、短半轴半径的影响,建立了刀具参数与轮齿接触特征之间的作用规律。研究工作为优化双重螺旋法的切齿加工参数提供了理论依据。     

基于渐开线齿轮的产形线切齿法研究

渐开线齿轮的加工方法有仿型法和展成法,目前在生产中使用的齿轮刀具,其中只有加工圆柱齿轮可获得要求的渐开线齿形。本文依据齿轮啮合原理,利用产形线形成共轭啮合的原理,采用共轭齿面接触线为刀刃构形的切齿刀具,这样构形的切齿刀具都非常简单,并且容易采用合理的几何角度。为创新开发新型刀具、机床、切齿方法以及新传动副提供了一种新的思路。     

环面渐开线齿轮的动态接触分析

以环面渐开线齿轮为研究对象,根据齿轮啮合原理及滚齿加工原理,利用产形齿条的齿面方程,分别推导出凸、凹环面渐开线齿轮齿面方程。根据不产生尖化或根切的数学条件,基于MATLAB开发了环面渐开线齿轮几何参数设计的Graphical User Interface。以环面渐开线齿轮齿面上点的三维坐标构建三维实体模型,并将实体模型导入Hypermesh中划分网格。基于非线性接触算法,建立凸—凹环面渐开线齿轮啮合的有限元模型,在ABAQUS中对其进行动态接触分析,结果表明环面渐开线齿轮齿宽受根切及尖化的限制,而在齿面接触应力方面,双齿啮合区齿面接触应力较小,单齿啮合区齿面接触应力较大。     

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...     

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.     

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.     

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.     

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....     

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.