变速箱外操纵护板拉深模设计与制造

变速箱外操纵护板,系典型的板料冲压件,本次设计和制造的模具是拉深模,根据该冲压件的特点,拉深模采用倒装式较好,采用刚性推件装置,采用弹簧压边装置,模具靠压力机的气垫通过托杆对压边圈作用进行压边,气垫的压边力随行程变化很小,可以认为是不变的,因此压边效果较好。采用导柱导套进行导向。该拉深凸、凹模的形状比较复杂,其工作部分带有R5的圆角和15度的锥度,其形状只能用自由曲面来描述,凸凹模的工作部分很难用一般的机械加工方法来加工,故应该采用数控铣削来加工。     

基于新型加减速曲线和实时控制方案的步进电机运行平稳性及噪声研究

基于步进电机的加减速曲线和控制方案两方面对步进电机的运行平稳性及噪声进行了分析和研究。首先通过角加速度和角速度的关系式(a-ω方程)构造出不产生柔性冲击的S型、e/e型及Cos型步进电机加减速曲线;其次优化步进电机控制方案,包括改善步进电机速度过渡的平滑性,运用迭代算法简化计算以提高控制器的运算速度,采用实时计算的方式节省存储资源。噪声实验结果表明,与传统的驱动方案相比,采用Cos型加减速曲线和实时控制方案的步进电机系统运行平稳,启动过程噪声明显减小。     

一种直径很小的减速器

提出了一种新型的减速器，它主要由两套螺母丝杆机构组成，第一套螺母丝杆机构将电机的转动转换为丝杆的移动，实现第一级减速，第二套丝杆螺母机构将移动又转换回螺母的转动，并实现第二级减速。这种减速器的优点是传动比很大，直径很小，适合于要求尺寸很紧凑的机器中。     

微型机控制步进电动机自动寻找最佳加、减速规律的研究

本文在分析了步进电动机加速、减速规律的基础上,研制了控制步进电机自动寻找最佳加、减速规律的微型机硬件系统和一套软件程序。对于单独的步进电机或带有负载的步进电机实用伺服系统,利用研制出的软、硬件可将其最佳加、减速规律自动找到,并将求得控制信息列表存入RAM中,然后微处理机就自动查表对步进电机实行最佳加、减速开环控制。这对于测定步进电机的快速性,以及使实用中的步进电机伺服系统处于快速起、制动运行状态有一定的实用意义。     

液压随动压边机构

在压力机上利用凸模、凹模压制各种形状复杂的薄片零件时,为了保证零件表面质量,须设置压边圈。施加在压边圈上的压力对一定形状和尺寸的零件要有一个定值。否则,若压力过大易压裂;压力过小易起皱。过去通常采用螺丝压边、偏心压边、弹簧压边及橡胶压边等。不过,这些压边形式产生的压边力,一方面压力大小无法调节和控制,另一方面也形成不了定值。而且只适合压制成型深度较小的简单形状零件。近几年来液压压边装置得到了应用,通过溢流阀可调节压边力的大小,适合于压制形状复杂、成型深度较大的零件。但这种装置往往要一套复杂的液压系统。需有电机、油泵、溢流阀、单向阀、调速阀及换向阀等。这种装置不但结构复杂,而且操纵控制麻烦。现介绍一种新型液压随动压边机构。该机构是在     

机械辅助血管介入治疗导丝输送力测量系统分析

为实现机械辅助血管介入治疗中导丝输送所受阻力的测量,针对导丝输送力信号测量和标定问题开展研究,提出了一种综合传感器位置信息的导丝输送力与传感器信号的标定方法。在此基础上,建立了导丝输送力测量系统并进行了输送力标定试验。实验结果表明,采用提出的标定方法较常规最小二乘法所获得的结果精度予以提高。     

钢管剪切装置控制方案设计

钢管剪切实验装置利用两台步进电动机同步改变两台丝杆升降机高度来实现任意轨迹剪切,具有结构简单可靠、柔性大等优点.首先介绍钢管剪切实验装置的工作原理与实际结构方案,建立剪切轨迹曲线与升降机高度的函数关系,利用普通两轴控制器实现对剪切装置工作轨迹的控制,然后给出了部分剪切方案的G代码指令.     

基于ANSYS Workbench的滚珠丝杆模态分析

滚珠丝杆传动速度的快慢、刚度的大小直接影响机床的加工精度。为研究其固有频率对步进电机的控制影响,采用SolidWorks对滚珠丝杆建立三维模型,在Workbench中进行网格划分与施加边界条件,并对其模态进行求解,得出其前6阶固有频率和振型。通过对各阶模态的固有频率和步进电机共振范围的比较,可确定步进电机的合理转速范围,也为滚珠丝杆的设计及其制造提供了参考依据。     

基于S曲线的步进电机加减速的控制

针对不同约束条件下步进电机加减速的控制问题,首先分析了S曲线算法原理,寻找s曲线算法与其它常见的步进电机运动控制算法之间的联系。然后在分析S曲线传统的七段模型后,提出了基于S曲线的步进电机加速度和速度控制方法,并讨论了当约束参数发生变化时实际的S曲线规划方法。最后,给出了不同约束条件下步进电机的加减速仿真曲线。研究结果表明,这种方法可以满足不同约束条件下步进电机加减速的控制。     

基于DSP的步进电机升降频控制

步进电机在启动和停止时容易发生失步和过冲的现象，为提高步进电机系统的定位精度，提出了一种按指数型加减速曲线控制步进电机升降频的方法，取得了较好的实际效果。     

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.     

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.     

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.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.