弧齿锥齿轮机床加工参数逆向求解的算法研究

研究了弧齿锥齿轮小轮机床加工参数反求的算法实现问题。推导了变性法加工的弧齿锥齿轮小轮齿面方程,建立了理论齿面向目标齿面逼近的最小二乘法优化模型,采用基于置信域策略的Levenberg-Larquardt迭代算法反求小轮的机床加工参数,并与广义逆矩阵法、截断奇异值分解法进行了比较。以小轮的某种修形齿面为例,3种算法识别的齿面与目标齿面的残余偏差平法和分别为1.472 3×10-3 mm2、8.296 9×10-4 mm2、1.499 3×10-5 mm2。结果表明,相对于前两种识别算法,采用基于置信域策略的Levenberg-Marquardt迭代算法可以大大提高齿面逼近的精度。该迭代算法为弧齿锥齿轮的齿面误差修正技术及齿面主动修形设计提供了应用基础。     

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。     

弧齿锥齿轮齿面误差的最少参数修正法

研究弧齿锥齿轮小轮齿面误差与调整参数误差之间的敏感性关系,基于SFT加工法得出对齿面误差影响较大的调整参数,提出齿面误差最少参数修正法。建立刀倾法加工的弧齿锥齿轮齿面数学模型,推导弧齿锥齿轮小轮的理论齿面方程和误差齿面方程,推导机床调整参数误差作用下的齿面任一点加工误差的解析表达式,提出机床调整参数误差对齿面误差的影响系数概念,依此判断各项机床调整参数误差对齿面误差的影响程度。通过理论齿面和误差齿面的比较,确定各项机床调整参数误差作用下的全齿面法向误差的变化规律。由解析法和数值法相互验证,确定弧齿锥齿轮加工过程中对齿面误差影响较大的调整参数误差项。利用函数法建立机床调整参数变化量与齿面法向误差的关系,采用序列二次规划法,求得机床调整参数修正量最优解。通过实例验证,提出的反调修正方法可以有效降低齿面误差。     

弧齿锥齿轮双重螺旋法加工数学模型及齿面偏差修正研究

建立了弧齿锥齿轮双重螺旋法加工的数学模型。基于齿轮啮合原理,完成了弧齿锥齿轮双重螺旋法加工齿面的数字化表达及离散化齿面点的构建,分析了各加工参数误差对齿面拓扑结构的影响程度;建立了齿面修正模型,通过算例验证,结果表明,齿面偏差得到了有效减小。     

螺旋锥齿轮齿面误差修正技术研究

研究了机床调整参数误差对双重螺旋法加工的螺旋锥齿轮小轮齿面误差的影响规律。基于齿轮啮合原理,使用MATLAB软件建立误差齿面方程,推导出了含机床调整参数误差的齿面离散点误差解析式,获得了对应机床调整参数误差的凹、凸两齿面误差拓扑图,分析了机床调整参数误差与齿面误差的映射关系,确定了对齿面误差影响较大的调整参数。借助2阶曲面对齿面误差拓扑图的近似表达,得出机床调整参数误差对齿面误差的影响权重。基于齿面误差及两齿面误差敏感矩阵,建立了齿面误差修正模型,通过广义逆矩阵的最小二乘法解超越方程组,获得机床调整参数的修正量。最后通过实例验证了误差齿面的修正效果,结果表明修正后凹凸两面的齿面误差大幅下降。     

螺旋锥齿轮齿面坐标的检测

螺旋锥齿轮加工时机床调整、试切、修正过程复杂,因此分析齿面曲面结构十分重要。本文利用Visual C 6．0及Madab 6．5编制出大轮齿面坐标的参数化检测程序,能够正确检验螺旋锥齿轮的齿面坐标,帮助加工人员快速地检测到螺旋锥齿轮的加工误差量,为螺旋锥齿轮的切齿调整提供准确的修正数据,为提高螺旋锥齿轮的加工质量提供了途径。     

弧齿锥齿轮齿面误差的分析与修正

建立SGM法加工的弧齿锥齿轮齿面模型,通过推导弧齿锥齿轮的理论齿面方程和误差齿面方程,比较两者之间的差异,分析研究弧齿锥齿轮加工参数误差对齿面误差的影响关系,并以此判断各项加工参数误差对齿面误差的影响程度,从而确定用于误差修正的参数个数,利用解析法求解得出对齿面误差影响较大的加工参数的调整修正值,达到修正弧齿锥齿轮齿面误差的目的。     

有误差的螺旋锥齿轮传动接触分析

以多体系统误差建模理论和齿轮啮合原理为基础,提出含有机床运动几何误差以及齿轮副安装误差的螺旋锥齿轮齿面接触分析(Error tooth contact analysis, ETCA)方法。以SGM法(大轮展成法加工,小轮变形法加工)加工的弧齿锥齿轮为例,通过ETCA分析,得到机床运动误差和安装误差对螺旋锥齿轮齿面加工质量影响的定量关系,对ETCA和TCA的结果进行对比分析,结果表明机床运动误差和安装误差对螺旋锥齿轮的齿面接触质量有较大的影响,为了通过齿面接触分析达到更准确的反调加工参数的目的,采用ETCA的分析结果指导加工参数反调更为合理。     

螺旋锥齿轮齿面离散点空间坐标及法矢的计算

根据螺旋锥齿轮的切齿加工方法和齿轮啮合原理,运用矢量运算的方法建立了大轮成形法加工和小轮刀倾法加工的理论齿面方程并规划了齿面计算网格点区域.运用Visual Studi0 2008编程环境,编写了理论齿面各离散点空间坐标及法矢的计算软件,通过该软件可计算得到螺旋锥齿轮理论齿面各离散点在齿轮坐标系中的坐标值和单位法矢.将得到的理论齿面坐标点及法矢导入到三坐标测量机中进行测量获得各离散点的齿形误差,然后将获得该理论齿面坐标点及法矢的参数输入到CNC3906齿轮测量中心进行齿形误差测量,获得齿面上各离散点的齿形误差.将两组齿形误差测量数据进行对比分析,论证了所开发的计算软件的正确性,为螺旋锥齿轮齿面偏差的测量以及螺旋锥齿轮数字化闭环制造提供了正确的理论齿面数据.     

圆弧刀廓加工螺旋锥齿轮的全齿面分区修形

针对圆弧刀廓加工螺旋锥齿轮副,以提高啮合传动平稳性为目标,研究了螺旋锥齿轮全齿面分区修形的方法。首先推导了圆弧刀廓双重螺旋法加工的小轮齿面方程,将圆弧刀廓修形和主动设计方法相结合,将螺旋锥齿轮齿面划分为5个修形区域,实现了对小轮全齿面的预控设计,得到了高重合度、低传动误差的目标齿面;并运用有限元技术对比分析了优化前后的齿面传动误差、齿面最大应力。结果表明:采用的全齿面预控修形方法降低了圆弧刀廓加工齿轮副的传动误差幅值,提高了重合度,降低了齿面应力;并反求出优化设计后的机床加工参数,为实际生产中制造高重合度螺旋锥齿轮提供指导。     

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.