基于反求技术的摆动从动件空间凸轮CAD

由于测绘点的实际接触点在理论上存在差异,摆动从动件空间凸轮机构的反求问题目前仍未获取很好解决,本文在空间凸轮反求ＣＡＤ中,担子 利用廓面测绘数据根据共轭面面原理反求出从动件运动规律,再利用该运动规律和有关结构参数重新解析设计出廓面的新方法。文中对反求方法和测绘数据进行了分析;提出了理论廓面、实际廓面的相关性质;在此基础上,利用共轭曲面原理导出了从动件运动反求的非线性规划数学模型,给出了算法。本文的     

基于ObjectARX的凸轮机构CAD系统的研究

一、前言 凸轮机构是一种常见的、能使从动件按照给定的运动规律运动的高副传动机构,然而,由于凸轮机构设计复杂、几何形状计算工作繁琐、凸轮轮廓的精度对输出响应影响较大以及凸轮的加工困难等原因,使得其应用范围及应用水平受到限制.     

基于Pro/E的止痛泵凸轮结构设计

止痛泵在临床治疗中得到越来越多的应用。本文首先在Pro/E环境下,根据凸轮从动件的运动规律,建立止痛泵结构中凸轮的廓线,从而完成凸轮的三维实体设计。利用Pro/E强大的造型功能,获得了合理的设计模型,同时还得到了凸轮的精确外形,为后续的分析及加工提供了便利条件。若需设计从动件运动规律不同的凸轮,只需更改运动规律,生成不同的运动规律简图,就可以改变凸轮的设计模型,这种方法操作简单,对各种结构的设计具有良好的借鉴作用。     

高速凸轮摆杆机构参数化设计技术研究

针对高速凸轮摆杆机构参数化设计过程中从动件摆动引起的凸轮转角偏移问题,分析了凸轮转 角偏移产生的原因及影响,提出了基于转角补偿量的参数化设计数学模型,实现了凸轮参数到凸轮轮廓曲线的 精确映射。以改进正弦运动规律为例,基于 UG 软件和二次开发平台实现了凸轮摆杆机构参数化设计和特征曲 线可视化,并通过 UG 运动仿真验证了数学模型和特征曲线的准确性。研究结果表明：推程和回程运动阶段凸 轮轮廓曲线对应的圆心角对比凸轮转角都发生了不同程度的偏移;基于转角补偿量的数学模型可以降低凸轮从 动件的最大加速度,实现凸轮轮廓曲线的精确设计,同时简化了凸轮摆杆机构的设计和修改流程,极大的提高 了设计效率。     

凸轮的计算机辅助设计

<正> 凸轮机构是一种常用机构,广泛地应用于自动化机械、仪表和各种操纵控制装置中,其最大优点就在于:只要凸轮的轮廓曲线设计得适当,就可以使从动件获得任何预期的运动规律。所以,凸轮机构设计的     

Pro/ENGINEER运动分析功能在数控编程中的应用

凸轮是机械传动系统中常见的构件之一,常用以控制从动件的运动规律,这实际上是凸轮的轮廓曲线在起作用.轮廓曲线的机械加工精度不仅影响单个凸轮的质量,更影响凸轮机构的传动效果,比如噪音、振动等,因而加工时应最大限度地逼近理论轮廓曲线.     

CAD在蜗形凸轮设计中的应用

1．引言蜗形凸轮机构是机械设备中运用很广泛的间隙运动机构之一，其参数选择灵活、传动平稳。分度精度高。蜗形凸轮的设计是该机构设计中的重要工作之一，目前普遍采用人工设计方法，其步骤为：选择从动件运动规律，计算机构的运动参数和几何尺寸参数，进行动力学计算，最后绘制零件图。这一系列繁杂的设计过程给设计者带来许多困难，工作量大，设计周期长。同时由于大量繁杂、重复的设计计算，使人工设计难免出错。而运用CAD技术进行蜗形凸轮设计，可使设计和工程计算、分析及模拟结合起来，实现优化设计，同时正确、迅速地绘制工程图。…     

凸轮自动加工微机控制系统

本文介绍了一种凸轮自动加工微机控制系统,它可用于加工盘形凸轮的铣床、磨床或线切割机床。还可用于凸轮毛坯的自动划线。由于采用微机控制,而不使用其他硬件,使其成本低,可靠性高。它适用于各种运动规律,不同从动件凸轮的加工。     

求余算法在程序语言中的运用

随着程序语言的不断发展,通过程序来仿真各种机构的运动变得十分普遍.传统的程序语言根据主从动件位置的对应关系.通过主动件计算从动件的角位移.算法繁琐,可读性不强.求余算法可以有效地降低程序的冗余度.增强程序的可读性.特别是对槽轮机构、齿轮机构及棘轮机构等一系列周向循环机构的动画演示程序,效果显著.通过槽轮机构的VB动画演示程序,介绍了求余算法的原理、特点和算法实现,并简单介绍了算法在数据结构循环队列中的运用,对算法做了拓展.     

凸轮曲线的计算器辅助设计

一、前言凸轮是机器上最常用的零件之一。虽然电气、液压、气动器件等广泛用于自动化系统,但专用自动化机床中,凸轮仍占重要地位。用作图法来求轮廓曲线,既烦琐又不准确。从动杆的运动规律一般可用解析式表达     

Computerized tolerance analysis of disk cam mechanisms with a roller follower

The tolerance analysis is one of the key elements of design and manufacturing of cam mechanisms. This paper presents a computerized method for analyzing the tolerances in disk cam mechanisms with a roller follower. By employing the concept of simulated higher-pair contact analysis, the kinematic deviation of the follower motion arising from the tolerance amount of each design parameter can be determined numerically. The offset translating roller follower and the oscillating roller follower cases are given to illustrate the proposed method. The tolerance analysis results show that, owing to the combined effects of various design parameters, the position accuracy of the follower motion may degrade considerably. But, the tolerance amounts of the design parameters may also have a compensating effect to enhance the relative accuracy of the follower motion between its high and low dwell positions. Hence, it is possible to find the optimal tolerance combination for balancing the kinematic accuracy and the tolerance amounts of disk cam mechanisms with a roller follower.     

离散光滑插值在CATIA V5中的实现

利用CATIA V5的二次开发工具CAA,在CATIA中实现了基于离散光滑插值算法的网格变形功能。首先介绍了CAA中点云数据的体系结构,然后应用离散光滑插值算法,并且结合四种常用的几何约束形式,在CAITA V5中实现了新的三角网格变形功能,并给出了应用实例。     

A method for modelling contact between circular and non-circular shapes with variable radii of curvature and its application in planar mechanical systems

Contact impact has been widely found in the operation of various mechanical systems. These mechanical systems include the type of mechanism typically characterised by circular–non-circular geometric contact. They consist of the mechanisms of the cam with a roller follower, a Geneva wheel with intermittent motion, a cog belt drive with circular-arc teeth, a cycloidal-pin wheel gear, and a roller chain drive. For the two components in contact, one component needs to have an ideal circular shape, while the other is characterised by its non-circular geometry, that is, the contact shape may present varying radii of curvature. Taking this kind of contact mechanical system as a research object, this work proposes a general method for analysing the problems concerning contact impact on this circular–non-circular geometry. This method discretises continuous non-circular geometries to acquire a series of discrete points. Then, the contact areas of components are determined by repeatedly judging the relationships between the positions for various discrete points and the circular geometric centres thereof. In the contact areas, the maximum depth of the contact is measured, and the positions of the contact points between components, in a direction along the maximum contact depth, are determined. Finally, the normal contact force and tangential friction force between contacting components are established at the contact points. This method can be applied to analyse the problems concerning single contact and multi-point contact among various contact components. To verify the validity of this method, this work takes an offset translational roller follower disc cam mechanism (with a single contact) and a cycloidal-pin wheel gear mechanism (with multi-point contact) as examples and investigates the dynamic characteristics of the contact impact for the aforementioned mechanical systems, respectively.     

Object-oriented cam design through the internet

We have developed a Web-based interactive cam design package under the programming paradigm of the language environment. This package was initially developed as a teaching and learning tool for educational use in an undergraduate Computer-Aided Mechanism Design course. Because the system is Web-based and implemented through a client/server model with the user interface through the Web browser, it is easy to use and maintain. The system can also be used to solve practical engineering cam design problems with flat or roller followers and with translating or oscillating motion types. The system can be used to generate the cam profile, transmission angle, position, velocity, and acceleration of the follower. Once a cam/follower system is designed, animation of the cam/follower system can be performed. At the end of the design, the CNC code for manufacturing the designed cam can also be produced through our Web-based cam design system. The package consists of a number of modules including various Web pages, common gateway interface (CGI) programs, a program called cam.ch, and the CCam class which performs the necessary computation for cam design. Two different versions of the cam design package have been designed and implemented. One runs the cam design program on the client machine as a applet, and the other runs the cam design program on the Web server through CGI. In this paper, details of design and implementation of Web-based cam design package will be described. Two application examples with different motion types for the follower will be used to illustrate features of the applet-based and CGI-based implementation schemes. The ideas of the Web-based software design presented in this paper can be applied to other application areas.     

Micro cam system driven by electrostatic comb-drive actuators based on SOI-MEMS technology

Microsystem Technologies - This paper reports a design and fabrication process of a micro cam system (MCS) with a flat-faced translating follower. The cam rim with cover diameter of 2.4&nbsp;mm...     

基于加权支持向量机的凸轮升程误差拟合方法

针对凸轮磨削加工过程中存在局部升程误差严重超差的问题,提出了加权支持向量机的凸轮升程误差补偿方法。首先根据圆率的符号判断凸轮升程误差值是否连续,然后建立了不连续点与相邻点之间夹角与加权值的关系。通过加权支持向量机对凸轮升程误差值进行拟合。然后将原始凸轮升程值减去经拟合后的凸轮升程误差值,获得新的凸轮升程值。再根据圆率自动调整加权值的系数,使凸轮升程值光滑点数最大,即获得最优的凸轮升程值。对上述算法进行仿真和编程,经YTM8336-16数控凸轮轴磨床进行磨削验证。实验表明,凸轮升程误差由原来的±0.059 mm降至±0.011 mm,表面粗糙度由Ra0.32μm降至Ra0.25μm,获得良好的效果。     

Direct Solvers for the Biharmonic Eigenvalue Problems Using Legendre Polynomials

We propose an efficient algorithm based on the Legendre–Galerkin approximations for the direct solution of the biharmonic eigenvalue problems with the boundary conditions of the clamped plate, the simply supported plate and the Cahn–Hilliard type. The key point to the efficiency of our algorithm is to construct appropriate basis functions which satisfying the corresponding boundary condition automatically and leading to linear systems with sparse matrices for the discrete variational formulations. In addition, the error estimate was driven by the minimax principle. Finally, the numerical results demonstrate the accuracy and the efficiency of this method.