Synthesis of a mechanism with a flexibly attached slider for space curve generationSynthese eines mechanismus mit flexibel gekoppeltem schieber zur erzeugung räumlicher kurven

Generation of space curves is rather a difficult problem and not much work is reported in the literature. Planar 4-bar mechanisms with rigid links have been investigated for plane curve generation but the methods reported are complex. In this paper a slotted link mechanism with a flexibly attached slider is proposed for space curve generation. Equation of motion for the slider mass comes out to be nonlinear but the solution, i.e. the displacement of the slider mass is expressed in a linear form so that the synthesis either by precision point approach or through the method least squares becomes extremely simple. An example problem is included.     

Dynamic synthesis of a 2-degree-of-freedom function-generator with flexible elements

Kinematic synthesis of planar 2-degrees-of-freedom linkages with at least seven links hitherto reported in the literature is very difficult due to the highly nonlinear equations that result. Special techniques are needed to solve these nonlinear equations. Both the formulation and the solution are extremely tedious and time consuming. In what follows a linkage with a flexibly attached slider is proposed. The differential equation of motion of the slider mass and its solution lead to a much simpler displacement equation which can be used for the closed form synthesis of a function generator for two independent variables. The resulting equations are linear simultaneous, the solution of which is a routine matter. The dimensions obtained can be used as starting values for optimisation by least squares method etc. An example problem is solved to illustrate the application.     

曲柄滑块机构连杆轨迹的同源机构与运动仿真

研究了利用数值图谱法进行带有预定时标的曲柄滑块机构连杆轨迹的尺度综合 ;对于其同源机构在尺度综合中的应用进行了探讨。通过开发的机构尺度综合 CAD应用软件 ,给出了曲柄滑块机构及其同源机构的运动仿真实例     

曲柄滑块型6杆函数机构的近似综合

以主动曲柄和从动滑块间的给定运动关系为基础 ,通过引入 2自由度 5杆机构及其连杆铰接点曲线 ,提出了曲柄滑块型 6杆函数机构的轨迹逼近———函数插值轮换综合法。最后用综合算例验证了本方法的正确性     

Use of orthogonal arrays in mechanism synthesis

No single optimization method exists that is best suited to solve all path generation problems effectively [Erdman 1991]. Graphical illustrations of the mechanism design space, given in this paper, attest to the difficulties encountered in the optimization of path generation tasks. An example has also been provided to illustrate the importance of a good initial guess in achieving proper convergence. Use of experimental design techniques that are based on statistically designed orthogonal arrays is suggested in this paper, as an alternate method to solve mechanism design tasks. It will also be benificial to use this method to obtain a good starting point for the traditional optimal synthesis procedures. Also, when a theoretical solution is translated into physical reality, manufacturing tolerances, joint clearances, and elasticity in link members cause variations in mechanism performance. Orthogonal arrays and the related robust design procedures, suggested here, account for such variations as well. Design examples are given to illustrate the use of orthogonal arrays.     

Kinematic synthesis and analysis of the rack and pinion mechanism for planar path generation and function generation for six precision conditions

The rack and pinion mechanism is synthesized for generating both three prescribed path points with input coordination and three positions of function generation. This mechanism has a number of advantages over the four bar linkage. First, since the rack is always tangent to the pinion, the transmission angle is always the same (optimum) value of 90° minus the pressure angle of the pinion. Second, with both translation and rotation of the rack occuring, multiple outputs are available. Other advantages include the generation of monotonic functions for a wide variety of motion and nonmononotomic functions for the full range of motion as well as nonlinear amplified motions. In this work, the mechanism is made to satisfy a number of practical design requirements such as a completely rotatable input crank and others. The method of solution developed in this work utilizes the complex number method of mechanism synthesis and the solution is programmed on a VAX 11/785 computer and is being made available to interested readers.     

曲柄滑块机构振动力和力矩的附加平衡机构

对机械中常用的曲柄滑块机构的振动力和振动力矩的平衡问题进行了探讨。提出了一种新的附加平衡机构。通过对机构的运动学和动力学分析，给出了振动力平衡的条件。振动力完全平衡后机构的振动力矩，可通过调整附加机构中偏心齿轮的回转中心得到部分平衡。根据振动力矩的均方根值最小原则，确定了偏心齿轮的回转中心的具体位置。提出的机构增加质量较小，不需要额外增加移动副。可以在工程中简化使用。     

Synthesis of mechanisms for single and hybrid tasks using differential evolution

The optimal dimensional synthesis for planar mechanisms using differential evolution (DE) is demonstrated. Four examples are included: in the first case, the synthesis of a mechanism for hybrid-tasks, considering path generation, function generation, and motion generation, is carried out. The second and third cases pertain to path generation, with and without prescribed timing. Finally, the synthesis of an Ackerman mechanism is reported. Order defect problem is solved by manipulating individuals instead of penalizing or discretizing the search space for the parameters. A technique that consists in applying a transformation in order to satisfy the Grashof and crank conditions to generate an initial elitist population is introduced. As a result, the evolutionary algorithm increases its efficiency.     

基于轨迹局部特性的机构并行优化综合

采用曲线离散点处曲率半径及相对转角作为局部特征参数表示平面连续曲线,建立包含多种机构的程序化轨迹数值图谱,构造基于局部特性的轨迹机构优化模型,利用遗传算法的多点搜索实现多种机构的并行优化,将机构的型综合与尺度综合在一定范围内合二为一。     

Design of single- and multiple-dwell six-link mechanisms through design optimization

Nonlinear programming techniques are applied to a class of six-bar linkages to produce single- and multiple-dwell mechanisms. The six-bar linkage consists of a four-bar crank-rocker mechanism driving a slider crank mechanism from a coupler point. The dwell position(s) may be specified at any value of input link rotation and may last for any reasonable duration. The total stroke and the location of the slider at each dwell position may also be specified. A design optimization problem is formed which attempts to generate a linkage in which the slider link will travel in a circular path and thus produce a dwell period in the cycle at the appropriate link position. This problem is then solved by an exterior penalty function technique. The linkage model is constructed using the vector loop approach and examples for both a single- and double-dwell mechanism are included. Extensions including velocity, acceleration and transmission angle constraints are also discussed.     

可调节型连续轨迹生成机构的优化综合

提出一种可调节型连续轨迹生成机构的优化综合方法。在确定了可调节型双曲柄机构轨迹柔性的基础上，基于从动杆杆长结构误差建立机构的优化综合模型，采用改进遗传算法获取综合结果。从动杆杆长结构误差不仅计算便利，且能有效反映出实际生成的轨迹曲线与预期的理想轨迹曲线间的差异，避免了在两轨迹曲线上选取对应比较点的困难。改进遗传算法保证了获得全局最优解。综合实例结果表明了本方法的有效性。     

Dynamics of the slider-crank mechanism with clearance in the sliding bearingÜber die dynamik des schubkurbelgetriebes mit lagerspiel in der kreuzkopffuhrung

A method of predicting the detailed motion of the slider of a slider crank mechanism within slider-guide clearance is given. The effects of changing the geometry and the mass distribution are presented, and the analysis, which includes the effects of gas loads on the slider, is applied to the motion of a piston in a diesel engine.     

用广义逆矩阵及Roberts-Chebyshev定理进行再现计时轨迹平面铰链四杆机构的近似运动综合

提出了再现计时轨迹平面铰链四杆机构近似运动综合的一种新方法。首先利用 Ｒｏｂｅｒｔｓ Ｃｈｅｂｙｓｈｅｖ 定理将再现计时轨迹四杆机构运动综合转化为刚体导引四杆机构的运动综合。然后用广义逆矩阵将刚体导引四杆机构的近似运动综合方程组转化为二元二次多项式方程组,采用连续法或消元法求解该方程组,即可得到刚体导引四杆机械近似运动综合方程组的所有解。由刚体导引四杆机构近似运动综合方程组的每一组解出发,利用 Ｒｏｂｅｒｔｓ Ｃｈｅｂｙｓｈｅｖ 定理,可分别得到再现计时轨迹四杆机构近似运动综合的两组解,这样便求得再现计时轨迹四杆机构近似运动综合的所有机构方案。     

可调节型曲柄摇杆连续轨迹生成机构的优化综合

提出了利用机架杆方向结构误差优化综合可调节型曲柄摇杆连续轨迹生成机构的方法。在确定了可调节型曲柄摇杆机构的轨迹柔性的基础上,基于机架杆方向结构误差建立机构的优化综合模型,采用改进遗传算法获取综合结果。机架杆方向结构误差不仅计算便利,且能有效反映出实际生成的轨迹曲线与预期的理想轨迹曲线间的差异,避免了在两轨迹曲线上选取对应比较点的困难。改进遗传算法保证了获得全局最优解。综合实例结果表明了本方法的有效性。     

定常力输出柔性滑块机构的优化综合

定常力输出机构就是在一定的输入范围内输出一恒定力的机构。本文首先利用虚功原理建立了实现定常力输出柔性滑块机构中力与位移间的关系式 ,进而提出了当考虑和不考虑零件中的应力时柔性滑块机构的优化综合方法 ,最后给出了优化综合实例以证明该方法的正确性     

Stephenson六杆机构近似位姿的计算机辅助几何法

机构尺寸综合的两个基本工具是几何法和解析法,它们只适用于位置较少的机构尺寸综合,而且解析法求解复杂不直观.提出基于CAD几何的Stephenson六杆机构近似位姿综合法.先用CAD的几何约束和尺寸驱动技术,在多个复合精确和近似位姿情况下,构造一个基本六杆模拟机构.再根据轨迹和运动综合的原则,由基本六杆模拟机构分别创造出轨迹和运动的近似位姿综合模拟机构.计算机模拟结果表明,这种方法不仅具有简捷直观、求解精度高和重复性好的优点,而且可以增加机构综合的规定位置个数,为机构的尺寸综合提供更有效的工具.     

平面连杆机构轨迹发生器的高阶综合

以运动约束原理为基础，讨论平面连杆机构轨迹发生器高阶综合的一种新方法，并给出全铰链三支座Ｓｔｅｐｈｅｎｓｏｎ型六杆机构的综合实例．     

Thermal diagnostics of friction in self-lubricating radial slider bearings with swinging movement: Part 1. Algorithm for determination of power function of heat generation

It is proposed to find the moment of friction in a slider bearing undergoing oscillatory motion by the solution of the inverse boundary problem of frictional heat generation on the values of temperature measured in the vicinity of a friction zone. Basic boundary value problems and relationships for construction of the algorithm to determine the specific power of heat generation are obtained.     

Synthesis of optimum slider-crank mechanismsCИ

For the spatial slider-crank mechanism formulas are obtained to allow the user determine the link sizes and slider offset for a predetermined stroke with an acceptable pressure angle at the extremes of slider travel as well as by a given angle between the crosshead guide of the slider and a plane in which the crank revolves. Formulas for determining the sizes of links of the plane slider-crank mechanism as a special case of the spatial mechanism are also presented. The particular cases of mechanisms havingequal angles of pressure as well as at extreme values of an angle between crosshead guide and the revolution plane of the crank are discussed. It is shown, that the plane mechanism case provides maximum slider travel when other things are equal.     

平面四杆机构刚体导引综合的小波特征参数法

针对傅里叶级数理论不能进行非整周期刚体导引综合的问题,提出了基于Haar小波级数的解决方法,将早期提出的解决平面四杆机构轨迹综合问题的方法扩展到平面四杆机构的刚体导引综合中。通过对刚体转角和其对应基本尺寸型的连杆转角小波系数进行分析,发现了二者的内在联系。在此基础上建立了101 408组基本尺寸型的平面四杆机构刚体导引输出特征参数数据库。将位置输出问题转化为平面四杆机构轨迹综合问题,并给出了计算平面四杆机构实际尺寸和机构安装位置参数的理论公式。利用建立的数据库和理论公式,实现了平面四杆机构非整周期刚体导引综合。以生产线上的输送工件的铰链四杆机构为例,证明了本文方法的有效性和可行性。