基于三级串联力放大机构的气动夹具设计及应用

介绍了由三个角度效应串联作用的三级力放大机构与无杆缸组成的气动夹具系统,给出了其力放大系数和输出力的计算公式.该三级力放大机构具有结构简单、布置紧凑的优点,将其应用于气动夹具中,能够显著减小气缸的直径.或是在气缸直径相同的条件下,夹具的输出力得到了明显的提高.     

增力自锁型手动夹具的设计及力学分析

设计了一种能够自锁的手动夹具增力机构,利用典型的杠杆、铰杆和斜楔增力模块组合成杠杆-铰杆-斜楔式串联传动机构,通过长度和角度效应,实现了力的三级放大。介绍了该机构的组成及工作原理,按照力学模型推导出了增力系数和输出力的计算公式,分析了各工作参数对增力效果的影响。该机构具有绿色环保,结构简单、紧凑,增力系数大等优点。     

铰杆——斜楔式气动夹具增力机构设计及力学分析

设计了一种气动夹具增力机构,是利用典型的铰杆和斜楔增力模块组合成铰杆-斜楔式串联传动机构,通过角度效应,实现力的三级放大.介绍了该机构的组成及工作原理,按照力学模型推导出了增力系数和输出力的计算公式,分析了各工作参数对增力效果的影响.该机构具有结构简单、紧凑、增力系数大等优点,同时可利用单一输入力,实现气动夹具对工件进行双侧对称夹紧的过程.     

具有三级力放大机构的气动夹具设计及应用

设计了一种由三级力放大机构和无杆缸组成的气动夹具系统,力的放大基于三个角度完成。该三级力放大机构具有结构简单、布置紧凑的优点,将其应用于气动夹具中,能够显著减小气缸的直径;或是在气缸直径相同的条件下,使夹具的输出力得到明显的增大。为解决气动夹具体积过大这一棘手问题提供了新的思路。     

偏心夹紧流体传动夹具

在常见的夹紧机构中,偏心夹紧机构不仅具有自锁和力的放大功能,而且具有结构简单和动作快速的优点。因此,偏心夹紧机构在手动夹具中得到了非常广泛的应用。但是,在流体传动夹具(如液压传动夹具和气动夹具)领域,由于受有杆液压缸(或气缸)结构的限制,使带有偏心夹紧机构的流体传动夹     

铰杆-杠杆串联组合机构分析及其应用

在对长度效应的杠杆增力机构和基于角度效应的铰杆增力机构进行分析分类的基础上,用串联、对称、反向、双向对中输出、双向浮动输出等创新演绎方法,创新设计出了系统性的单边铰杆-杠杆串联组合增力机构和双边铰杆-杠杆串联组合增力机构,形成了该类机构的完整图谱,并对各类型机构进行了力学分析,最后应用到实践中。     

基于三级增力机构的气动肌腱压紧装置

介绍了由2个角度效应作用的三级力放大的气动肌腱压紧装置,给出了工作原理和力学计算公式及其力放大系数。该机构结构紧凑,能对输入力进行高倍放大后输出。     

四杆机构替代齿轮机构的设计方法

四杆机构与齿轮机构都是比较古老的传动机构,由于其各有特点,故在机械工程中都得到了广泛应用。两者相比,齿轮机构传动平稳,分度精确,但加工、安装、维护的要求比四杆机构高。因此,在一些运动要求不严格的场合,可以利用四杆机构安装、维护、加工比较简单的特点替代齿轮机构。如我厂的下煤仓嘴,结构简图如图1所示。要求机构的左、右鄂板在汽缸的作用下向左、右打开,将煤放出。     

串联气缸驱动肘杆-杠杆增力机构内夹持装置设计

介绍了一种基于肘杆—杠杆增力机构的串联气缸驱动的内夹持装置的创新设计思路,说明了其主要工作原理和基本的技术性能,并给出了说明参照图片和相应的夹紧力计算公式,介绍了这种机构的主要优点和优越性能。所介绍的这种内夹持装置机构,主要是以串联气缸、肘杆—杠杆增力机构来解决气压传动输出力不足的缺陷,以满足较大的输出力,而且通过变换杠杆的形状和长度以满足不同尺寸工件的加工要求,整体结构采用对称布置,使得整体布局美观。     

基于固定式无杆活塞缸驱动的增力夹紧机构

介绍了由固定式无杆活塞缸驱动的增力夹紧机构及其优越性,分析其工作原理,并给出了理论、实际夹紧力和力放大系数的计算公式.     

断路器弹簧操动机构双四杆机构优化设计

断路器弹簧操动机构中四杆机构的结构参数直接影响着断路器动触头的速度和位移。很多厂家在生产弹簧操动机构过程中,四杆机构设计较多为经验设计,需要不断试验、修改、比较。为适应实际生产过程中不同机构输出要求,能够快速准确给出四杆机构系统的理论设计方法和修改方案尤为重要。文中通过分析四杆机构与断路器弹簧操动机构的输出特性的关系,按照输出力特性设计铰链四杆机构结构参数。基于粒子群优化算法求解计算结果,运用MATLAB编程设计图形用户界面。图形用户界面中通过调整相应参数可以快速修改方案并得到计算结果,使弹簧操动机构四杆机构设计直观方便。     

Analytical modeling and FEM Simulations of single-stage microleverage mechanism

Microleverage mechanisms have potentially wide applications in micro-electro-mechanical systems (MEMS) for transferring an input force/displacement to an output to achieve mechanical or geometrical advantages. Constrained by micro-fabrication technology, a microleverage mechanism is made of planar flexures, achieving mechanical transformation through elastic deformation. This kind of mechanism is referred to as a compliant mechanism. In this paper, the analysis and optimization of a single-stage microleverage mechanism is presented with a double-ended tuning fork as the output system in a resonant accelerometer to address the design issues. A very good agreement is obtained between the results of analytical modeling and those of FEM simulation with a SUGAR software package. Although the SUGAR data are more accurate, the analytical equations give clearer insights as to how to design a microleverage mechanism. While high axial spring constants and low rotational spring constants are desirable, the axial and rotational spring constants at pivot need to match those at the output system to achieve the maximum force amplification factor. This compliance-match concept is very important for the design of both single-stage and multiple-stage leverage mechanisms.     

一种形封闭型手动压力机

介绍一种形封闭型手动压力机的工作原理,并给出其力学计算式.该压力机利用偏心凸轮机构与二次正交连杆增力机构的串联组合,给手柄施加一个较小的作用力,能够获得一个很大的输出力.由于采用形封闭型偏心凸轮机构,可在不需要复位弹簧的条件下,仅依靠反向转动偏心凸轮,便可实现压头的复位.     

The force transmissivity index of planar linkage mechanisms

In this paper, a new force transmissivity index (FTI) of planar linkage mechanisms is proposed. The index is used to quantitatively measure the force transmission quality from the input link to an output link. Traditionally, the transmission angle is used to measure the ability to transmit motion for planar four-bar linkages. However, the transmission angle is usually limited to be used at four-bar linkages due to the structural simplicity. For complex multi-loop mechanisms, it is often difficult to define the force transmissivity. Here we have established a procedure of force transmissivity analysis for planar linkage mechanisms. The method is based on the static force analysis and the concept of power flow path. It is found that the force transmissivity of a mechanism depends not only on the configurations of the mechanism, but also on the selection of the output link and the forms of the loading. We have compared the results based on the FTI with the results from the Jacobian matrix method and the joint force index (JFI) method for four-bar mechanisms. It shows that the proposed FTI can describe the force transmission performance more accurately than other methods do. It is concluded that the index can be used as a better measure of force transmissivity analysis for planar linkage mechanisms.     

曲柄摇杆机构依据最佳传力性能的图解优化设计

本文讨论了平面连杆机构中有关行程速比系数和极位夹角的概念问题,分析了极位夹角在曲柄摇杆机构中的取值范围及其对机构传力性能的影响,并在此基础上提出了简便易行的图解优化设计方法。     

Thickness improvement in single point incremental forming deduced by sequential limit analysis

Multistage forming is one of the most practical solutions to avoid severe thinning in single point incremental forming (SPIF). A successful implementation of multistage SPIF is strongly dependent on an appropriate deformation path. In this paper, firstly, a simplified modeling technique is proposed using sequential limit analysis. It is shown that sequential limit analysis can predict the thickness distribution faster than an equivalent model in a commercial finite element modeling code like Abaqus can. The reliability of the model is assessed by comparing experimental and simulated results for single-stage and multistage SPIF cones. This model is utilized to study the effect of various deformation paths on the thickness distribution. As a result, a new multistage strategy is designed and implemented to form a 70° wall angle cone in three stages. The thickness distribution of the cone is improved significantly compared to cones formed by a single-stage and a conventional three-stage strategy. Besides this improvement, the new multistage SPIF can be carried out in much less time.     

四构件带传动机构引导给定轨迹的研究

介绍了一种新型机构 ,即将四连杆机构中的其中两个构件用盘状构件和柔性带替代 ,组成一四构件带传动机构。该机构用于点的轨迹引导较一般的四连杆机构具有结构简单、引导精度高、传力性能好的特点。最后通过算例详细地叙述了该机构引导给定点轨迹的原理和方法。     

Non-axisymmetric flow field in an axial impulse turbine

Phenomena such as hard landings or geometric flaws can cause non-axisymmetric tip clearance in turbines. Such geometric imperfections induce flow distortions which can, in turn, cause self-excited vibration of the rotor, or rotordynamic instability. Flow field perturbations in a single-stage, unshrouded impulse turbine caused by non-axisymmetric tip clearance have been investigated experimentally. Steady velocity and pressure data have been acquired at the design point with and without static turbine casing offset. Perturbations in tangential velocity and casing wall pressure have been obtained, and rotordynamic forces along and perpendicular to the axis of offset have been inferred. Compared to an unshrouded 20% reaction turbine, the forces due to tangential force asymmetry are much smaller, but the forces due to pressure asymmetry are comparable.     

四杆直线导向机构综合新方法的研究

提出了四杆直线导向机构综合的数值比较法,运用鲍尔点附近的连杆曲线以３阶精度逼近给定的直线,建立起了连杆曲线中具有直线段的四杆机构数据库。将给定的直线段条件与数据库中的参数进行比较,即可得到一系列满意的四杆直线导向机构。该数值比较法解决了四杆直线导向机构综合的难题。应用该方法编制了一套四杆直线导向机构综合的设计软件,对单、双直线导向机构进行了综合与仿真,实现了导路上无摩擦、磨损的四杆直线导向机构综合的自动化与可视化,大大缩短了设计周期。