平面五杆机构的惯性力平衡问题的研究

平面双自由度五杆机构惯性力平衡 ,可以通过加平衡质量来实现。通过对此类杆机构的研究 ,可以得到其惯性力完全和部分平衡的条件 ,并对一种特殊形式的双自由度五杆机构进行了分析。给出了实例 ,对惯性力平衡的效果加以仿真 ,并与不加平衡措施的机构就仿真结果进行了对比     

平面机构惯性力部分平衡最佳平衡量的选取

论述了构件质心加速度或角加速度产生的惯性力对平面机构的影响及其主要平衡方法。根据惯性力平衡的原理。利用回转质量能够部分平衡曲柄滑块机构惯性力；并以曲柄滑块机构为例，以剩余惯性力的最大值为最小作为优化目标进行最佳平衡质量的选取。给出了求取最佳平衡量的简单计算框图。     

平衡曲柄滑块机构惯性力的研究

论述了曲柄滑块机构在高速运转过程中会产生很大惯性力的原因,并提出了部分平衡惯性力和完全平衡惯性力的常见方法.     

曲柄群机构的惯性力和惯性力矩平衡

在对曲柄群机构特点进行探讨的基础上,进行了曲柄群机构的惯性力和惯性力矩的分析,给出了曲柄群机构惯性力和惯性力矩平衡的条件,得出了在实际应用中对曲柄群机构进行惯性力和惯性力矩平衡的方法。结果表明,在曲柄群机构中确定适当的平衡质量的质径积使机构满足惯性力平衡后,只需在设计中调整连杆质心在特定位置,即可满足该机构惯性力矩的平衡。该结果对于工业生产中设计曲柄群机构的结构尺寸,以减小或消除该机构的基础振动有一定的实际意义。     

刚性连杆机构平衡问题综述

连杆机构的平衡由来已久,1968年G·G·lowen对惯性力、惯性力矩和输入力矩的平衡方法已进行了全面的总结,对惯性力的完全平衡,归纳为五种方法,即质量替代法;主要点向量法;线性独立向量法;凸轮平衡法和对称机构平衡法。惯性力矩的完全平衡,归纳为三种方法,即凸轮平衡法;齿轮平衡法和对称机构平衡法。输入力矩的平衡则主要采用飞轮和弹簧。惯性力和惯性力矩的部分平衡,则主要用齿轮平衡重平衡其简谐波部分。本文仅就刚性平面连杆的平衡问题综述如下: 一、震动力的平衡 72年F·R·Tepper对“线性独立向量法”作了进一步的补充,一是应用回路原理证明了一个机构能否进行完全力平衡的条件;二是得出了可进行完全力平衡的一般n杆平面连杆机构的最少平衡重数量为n/2的结     

基于ADAMS直线往复振动筛惯性力平衡的研究

利用三维建模软件Pro/E,建立了直线往复振动筛(以下简称振动筛)的实体简化模型;并通过数据交换,导入动力学仿真软件ADAMS中,建立了直线往复振动筛的运动学模型。在适当增大机构尺寸的情况下,对稳定体筛体的惯性力进行了部分平衡设计,减少了整个振动筛的总质心运动范围,使总质心运动稳定,减少了机构的惯性力,进而减少了机构的振动,提高了振动筛的使用寿命。在稳定体填充量不同的几种情况下进行仿真,将各种情况下的惯性力平衡效果进行对比,得出最佳方案,为振动筛或类似机构惯性力的部分平衡提供参考和借鉴。     

曲柄滑块机构惯性力优化平衡的新方法

针对曲柄滑块机构的部分平衡,提出了一种新方法。这种方法考虑了最大惯性力和惯性力绝对值的平均值两项优化指标,能更加合理地选择最佳平衡量,并且给出了设计算例和计算结果,结果表明这种方法效果良好,具有较强的理论价值和实用价值。     

精梳机钳板机构的振动平衡优化

钳板机构是纺织工业上精梳机的关键部件,在工作时钳板系统做前后往复运动,引发的振动平衡问题一直是国内各厂家进一步提高纺纱速度的技术难点.文中对钳板机构惯性力平衡进行了分析,得出了该机构惯性力完全平衡和部分平衡条件;运用线性无关向量法,以在一定范围内能完全覆盖总质心轨迹的矩形面积最小为目标函数,摆轴的质量和质心位置为优化变量,利用matlab编制程序对钳板机构的惯性力进行了平衡优化.研究结果有助于指导精梳机的设计,改善惯性力引起的振动,提高精梳机的速度.     

某型号收割机割刀机构及其传动部件惯性力平衡的研究

针对某型号收割机割刀执行及传动机构的实际工作中的性能需求,在完成机构惯性力最小的基础上,考虑实际工作情况权衡各方面因素的部分平衡的最优方案,最终得出了最优的设计参数,其研究方案可为类似杆机构惯性力平衡问题提供有益的参考。     

曲柄滑块机构惯性力部分平衡的研究

指出了以往运用质量代换方法对曲柄滑块机构惯性力进行部分平衡的不足，运用MATLAB编程计算重新描绘出分别考虑一级惯性力和二级惯性力时各惯性力的变化曲线，通过优化程序重新估算了使机构中残存的最大惯性力的最小配重条件，并进行了理论对比。     

Formation of a flange from a flat blank with a hole

A model of axisymmetric formation of a flange from a flat blank with a hole by expanding by a hard punch with a fixed flat flange is given, taking into consideration contact friction, change of wall thickness, strengthening of material, and the tool bending radius. Elastic, elastic-plastic and hard-plastic process stages are studied.     

变遗憾为精彩

从我做杂志起,我就知道自己选择了一个创造遗憾的职业,一个需要不停地变遗憾为精彩的职业。 每期杂志的出版都使我惴惴不安,在反思杂志的不足与期盼您评判到来中度过,在深入的思考与尖锐的批评中杂志不断汲取了营养,     

用体视显微镜改制体视摄影器

详细地介绍了XSD型体视显微镜改制体视摄影器的方法与效果。并提出摄影接筒的长度可为30～225mm,其变化对摄影器总的放大倍数没有影响。     

高效镜面抛光技术

一次加工就可将刀槽表面抛光到镜面质量。DIAMETAL公司最新开发的MNT-MS金刚石砂轮以其卓越的加工能力而备受关注。他们甚至还可以一次就加工完成深度达若干毫米的刀槽。     

Collision between a ring and a beam

With car–parapet collision accidents in mind, a normal collision between a free-flying half ring and a simply supported beam with/without axial constraints is studied, in which an elastic–plastic half ring with an attached mass and the elastic–plastic beam are taken as the simplest models of a car and a parapet, respectively. Particular attention is paid to the energy partitioning between the two structures and the evolution of the contact regions during collision. A mass–spring finite difference (MS–FD) model is employed whilst the large deflection and axial stretching/compression are incorporated. The numerical results show that the less stiff (i.e. softer) structure will dissipate more energy and the contact regions will move away from the initial contact points. With the increase of the relative thickness of the beam to the ring, the final deformation of the half ring will transform from a “U” shape to a “W” shape.     

Estimation of a Bottom Echo-Signal Level Reflected from a Plane Surface of a Cylindrical Article Using a Normal Probe Operating in a Pulsed Mode

The influence of the pulsed operating mode on a bottom echo-signal level reflected from a plane surface of a cylindrical article is studied during variations in the article's radius. It is shown that the pulsed character of a signal smoothens this function significantly as compared to that in the previously computed continuous mode. Numerical estimates of the bottom echo signal have been made for the ultrasonic inspection of wheel-pair axles of railway vehicles.     

八关节三动杆蛇形机器人的运动模拟

蛇形机器人是一种高冗余度的机器人,由于其结构可变形,能够通过松软地面以及跨越(或避开)障碍物,能代替人完成某些危险场所如核电厂等维修及城市搜救.本文提出了一种类正弦波形的八关节三动杆蛇形机器人结构,做了运动模拟并给出了结论,该蛇形机器人的研制成功为设计相关类型的机器人提供了参考.     

On the problem of a longitudinal impact on a bar supported with a plate

The wave processes that evolve in a plate-supported bar hit with a hard striker with a yielding spherical impact surface are considered. The linearized Hertz contact characteristics are used to derive analytical solutions describing the wave processes that may be conveniently applied for engineering calculations. The reliability of the results obtained with the proposed models is confirmed by experimental data.     

Solving a new mathematical model for a hybrid flow shop scheduling problem with a processor assignment by a genetic algorithm

This paper presents a new mathematical model for a hybrid flow shop scheduling problem with a processor assignment that minimizes makespan (i.e., C _max) and cost of assigning a number of processors to stages. In this problem, it is assumed that there are a number of parallel identical processors which are assigned to all of the stages with an unlimited intermediate storage between any two successive stages. To solve such a hard problem, first a new heuristic algorithm is proposed to compute the makespan that is embedded in the proposed genetic algorithm in order to find the best sequence of jobs, and then processors are assigned to the stages simultaneously. A number of test problems have been solved and related results are illustrated and analyzed.