A CAD/CAM System for High Performance Precision Drum Cams

This paper describes a computer-aided design and manufacturing system for the design and production of complex profiles for high-performance drum cams within the specified tolerance. The system graphically generates the cam profile on the cylindrical drum after performing an analysis of the kinematic performance for the prescribed follower motion, using a B-spline representation of follower curves. Eight different types of follower motion for a translating follower are considered. The kinematic performance is based on the criteria of achieving the lowest levels of velocity and acceleration for each curve. The system is also able to simulate the motion of the designed cam graphically. The system also recommends the best cam profile on the basis of comparing the kinematic performance of all the B-spline representations of all the follower motions.     

Machining of plate cam profiles on CNC machine tools using a highly integrated part programming system

The concept of NC (Numerical Control) and CNC (Computerised Numerical Control) in machine tools has contributed a great deal to automation and flexibility in manufacturing. In small/medium batch manufacturing, machining of complex contours with conventional machining is neither economical nor accurate. These can be achieved on a CNC machining centre more economically. The can machining system is designed to provide the necessary CNC program blocks for machining the plate cam profiles. The cam profiles can be defined by geometric curves, by follower motion or through a set of points. A promising new concept for approximating the tool path close to the defined cam profile, within the specified tolerance, has been proposed. The CLIP algorithm, presented in this paper, automatically chooses the best of the available interpolations (e.g. linear and circular interpolations) for selecting the intermediate points on the profile to guide the cutter for machining the profile. It provides the minimum number of intermediate points. This module can also be used for machining the elliptical profiles and pockets. The cam module, with little modification, is also used for machining the scroll threads of any pitch.     

凸轮的新型精确设计及加工方法

随着社会的发展,技术的进步,对机械零件的设计、加工精度要求越来越高。同时,随着CAD\CAM的发展,逐渐把提高零件的精度引入到通过软件来实现。通过对三维设计软件SolidWorks及其凸轮设计插件Camtrax的深入研究,介绍了凸轮设计和数控加工过程的最新方法。该方法不但可提高凸轮设计的精度,而且减少了凸轮设计及加工时间。     

设计盘形凸轮廓线的相对速度法

提出了一种利用凸轮与从动件的相对速度设计盘形凸轮轮廓的新方法，该方法基于从动件和支承绕凸轮轴线反转的原理，利用从动件上的接触线或者滚子轴线相对固定凸轮的速度和凸轮与从动件的几何关系设计盘 形凸轮轮廓，应用该方法导出了四种不同类型凸轮机构的凸轮廓线的解析表达式，并给出了对应的设计实例。     

基于不同滚子从动件类型的弧面凸轮CAD集成系统开发

目前弧面凸轮CAD系统大多都只针对单一类型滚子从动件类型而创建,不能很好地满足用户的需求。因此,本文针对不同类型滚子从动件建立起弧面凸轮廓面统一方程,并在此基础上利用UG／OpenAPI和VC＋＋6．0联合开发了弧面凸轮CAD集成系统。此系统有效地集成了不同廓面类型弧面凸轮的设计和建模功能,并通过UG界面实现三维实体造型结果的输出。最后通过实例证明了此系统的正确性,为后续数控加工刀位数据的生成和运动学分析等奠定了基础。     

凸轮轮廓设计的速度瞬心法

利用凸轮机构的速度瞬心,推导了直动从动件凸轮机构的凸轮廓线方程式,提出了一种新的凸轮廓线解析设计方法,为高精度加工凸轮提供了必要的理论依据。     

空间凸轮机构压力角自动求解的一种新方法

在凸轮廓面自动综合基础上 ,提出空间凸轮机构压力角自动求解的一种新方法。该方法在凸轮廓面数值自动综合的过程中获得接触点上的法矢 ,从而同时求得该位置的机构压力角。这种方法将各种类型凸轮机构的压力角求解按从动件运动方式统一起来 ,为凸轮CAD系统的构建提供了一致的求解模型 ,避免了廓面解析公式和压力角公式的繁琐推导。     

平行分度凸轮机构的类型综合

提出以机构运动谱进行平行分度凸轮机构类型综合的方法.机构运动谱包含了影响机构类型的多种信息:头数H、从动盘的滚子数、分度数、凸轮与从动盘的初始相对位置和相对运动配制,可以较全面地反映机构的运动特征和分度凸轮的结构特征.采用机构运动谱描述机构类型,将有利于建立分度凸轮轮廓的通用设计模型和分度凸轮的统一制造标准.     

空间同心滚子从动件凸轮机构的啮合计算公式

本文将直动从动件圆柱凸轮、蜗杆凸轮等归为一类，用共轭曲线原理导出了它们的精确的啮合计算公式，如压力角、凸轮工作曲面方程、相对速度、沿接触线法线方向的诱导法曲率等。这些公式为提高这类凸轮的设计质量，建立它们的ＣＡＤ系统提供了基础。     

地毯簇绒机横动等径凸轮的计算机辅助设计

地毯簇绒机中用于针床横动的机械凸轮是一种等径共轭凸轮,它的设计与地毯花形图案密切相关.分析了横动等径凸轮的设计原理,提出了由地毯花形走针图求得凸轮从动件运动规律曲线的数学转换算法,提出了基于Delphi的横动凸轮计算机辅助设计方法.用户可根据地毯实物花形图,输入花形针数、从动件运动规律、基圆直径和滚子直径等参数,就可绘制凸轮廓线,并输出用于横动等径凸轮数控加工的数据点.     

空间凸轮精密测量及运动规律反求研究

根据空间凸轮的特点,给出了空间凸轮精密测量及测球半径补偿方法,并编制了可实现实时测球半径补偿的空间凸轮专用测量程序.利用NURBS实现了凸轮轮廓曲线的重构,并给出基于运动仿真实现迅速反求空间凸轮机构从动件运动规律的方法.实验结果表明,该方法能快速、准确地实现空间凸轮的精密测量及从动件运动规律反求.     

A novel reverse measurement and manufacturing of conjugate cams in a diesel engine

This study presents a novel reverse measurement, CAD/CAM, and practical machining of conjugate cams on a computer-numerical-controlled (CNC) machine. This paper consists of five main components: a novel reverse measurement, displacement curve equations, CAD/CAM, practical machining and tests of the conjugate cams in a diesel engine. The diesel engine can output the 13-horse power and the rotational speed of 3500 rpm at the maximum. The results reveal that the torque and power are in good agreement between the reverse and the original conjugate cams in a diesel engine.     

CNC齿轮测量中心上盘形凸轮测量方法研究

研究了直接在CNC齿轮测量中心上检测凸轮并评定误差的方法和理论。在凸轮工件型面上直接采集测量数据,用三次样条插值函数拟合测头中心轨迹,通过测头半径补偿和凸轮从动轮数据转换,得到凸轮升程曲线,运用最小条件法评价凸轮升程误差。此方法具有测量过程简便、测量效率高、计算精度高、应用性广等优点,适用于以CNC齿轮测量中心为检测设备的自动加工系统。     

基于VB和MasterCAM的凸轮参数化设计与加工仿真

介绍了一种凸轮的参数化设计方法。基于解析法设计凸轮轮廓曲线的数学模型,以VB为主体开发语言,实现_『凸轮轮廓绘制,并直接导出坐标值,再利用MasterCAM读取坐标值,最终实现了凸轮的数控自动编程和模拟加工。此方法大大简化了凸轮的设计计算,有利于实现凸轮的CAD／CAM一体化。     

Calculating actual profiles of conjugate disk cams by means of conjugate variation measurement

For an assembled conjugate cam mechanism with two separate oscillating roller followers serving as a conjugation measuring fixture, when the cams rotate, the variation of the subtending angle between the two follower arms can indicate the variation of the cam profile errors. The profile errors of the assembled conjugate disk cams can be indirectly calculated by means of the conjugate variation measurement and the inverse conjugate variation analysis. That is, if a pair of master conjugate cams with known profile errors is available, by means of the measured subtending angle variations of the follower arms induced by a pair of assembled conjugate cams that consists of one master cam and the other being the inspected cam, then the actual profile of the inspected cam can be calculated by applying the inverse conjugate variation analysis. In order to verify the presented concept, experiments meant to calculate the profile errors of a pair of machined conjugate cams were conducted to compare with the measuring results obtained by using a coordinate measuring machine. The experimental results showed that the calculated cam profiles were well consistent with those of the measured ones. The presented method can be an effective alternative means for examining profile errors of assembled conjugate disk cams and could be useful for the quality control in mass production of conjugate cams.     

A CAD/CAM system for precision cams with three CNC interpolation methods

Design and manufacture of cams are complicated engineering tasks usually performed independently of each other. Therefore, a CAD/CAM system for cams would be very useful. The mathematical cam profile must be interpolated at some increment to create the numerical data for CNC machining. The interpolation method has significant effects on the dynamic performance. The focus of this paper is to develop a methodology of computer-aided design and manufacturing for precision cams by consideration of three CNC interpolation methods: linear, circular and R-. Various aspects of the features of the interpolation method are explained and compared. The presented software can simulate a roughing and finishing sequence on a given cam blank. The computerised procedure is detailed with accompanying examples.Nomenclature D_p(h) Jacobian matrix of family at pointp - ⁿ n-dimensional Euclid space - curvature - pressure angle - e offset - h _f family of follower - L step length - s displacement of the follower - first derivative of the displacement with respect to cam angle     

基于Pro/E关系式的圆柱凸轮建模方法研究

针对不同类型的圆柱凸轮机构的空间运动特点,建立啮合过程中滚子与凸轮的空间相对运动关系,研究了在Pro/E平台上利用关系式对圆柱凸轮建模的方法,对移动从动件圆柱凸轮机构采用Pro/E可变截面扫描工具建模,对摆动从动件圆柱凸轮机构使用方程式工具建模。通过在凸轮毛坯模型上建立理论轮廓曲面,并对其法向加厚、实体切除操作得到工作轮廓曲面,完成了圆柱凸轮的精确建模,其建模过程清晰、简练。建模时均使用参数表达,能够实现参数化和系列化设计,以提高效率。     

新型平行分度凸轮机构的综合与仿真

提出了一种新的平行分度凸轮机构 ,它的特点是其分度凸轮具有自共轭的凸轮齿 ,使分度期凸轮具有连续的工作表面 ,从而能够提高机构的动态性能。介绍了该机构的模型和工作原理 ;通过分析和综合 ,给出了该机构存在的一组参数。应用相对运动法导出了自共轭凸轮齿的齿廓方程。基于对该机构的综合结果 ,开发了平行分度凸轮轮廓自动设计和机构运动仿真的CAD程序。设计示例表明 :新机构的运动原理是可行的     

连续分度空间弧面凸轮的多轴数控加工工艺研究

利用空间啮合原理推导了连续分度弧面凸轮的廓面方程,分别基于范成法和仿自由曲面法加工原理建立了连续分度弧面凸轮的通用四轴和五轴数控加工工艺。该工艺已成功应用于连续分度弧面凸轮的多轴数控铣削加工,为连续分度空间弧面凸轮CAD/CAM/CNC系统研究奠定了基础。     

实现轨迹的凸轮连杆机构CAD及图形仿真

针对联动凸轮轨迹再现机构设计和计算都比较复杂的情况,提出了一种基于VBA(嵌入在Auto CAD图形系统中的Visual Basic语言)的轨迹再现联动凸轮机构CAD及图形仿真.该CAD算法和相应的软件程序将联动凸轮轨迹再现分成4个能独立运行的模块,即输入轨迹点数值模块、构造从动件运动规律模块、构造凸轮轮廓曲线模块及联动凸轮机构轨迹再现图形仿真模块.该图形仿真采用了在Auto CAD系统中动态精确显示机构运动简图的方式显示设计结果,因而设计结果具有直观和可靠的特点.