共查询到20条相似文献,搜索用时 78 毫秒
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并联机构的静刚度大、动力响应迅速等优点,使其在金属切削机床、工业自动化、医疗设备等领域具有广泛的应用前景;然而,并联机构在运动学、动力学等方面上的复杂特性使它在实际应用遇到许多困难。从传统并联机构的性能出发,结合并联柔索机构的特点,提出了一种基于刚柔结合的并联机构的新构型。对基于刚柔结合的并联机构进行构型设计,在此基础上,对影响机构精度的主要因素和误差问题进行分析。基于刚柔结合的并联机构在保持机构原有特点的基础上,提高了机构的精度和动力学性能,并有效的抑制了机构在运动过程中的振动问题,为机构的应用奠定了良好的基础。 相似文献
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一种新型完全解耦移动并联机构的运动和奇异性分析 总被引:1,自引:0,他引:1
提出一种新型三自由度完全解耦移动并联机构,机构的三条分支中各包含一个平行四边形结构,推导出该机构运动位置和速度的正、逆解析解,讨论了机构主动副的移动范围,并根据机构正、逆雅可比矩阵的奇异性对机构奇异位形进行了系统地分析。由于在整个运动过程中机构雅可比矩阵为三角阵,因此机构为完全解耦并联机构,这使得机构在控制和轨迹规划等方面较为简单。此外,分支中平行四边形结构增加了机构的刚度。该机构在坐标测量机和虚轴机床等方面具有广阔的应用前景。 相似文献
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电机驱动型广义机构概念设计知识库的建立方法和应用 总被引:3,自引:2,他引:1
在现代机构学及计算机辅助概念设计(CACD)深入研究的前提下,探讨了广义机构的形成与发展,对广义机构进行了分类。剖析了现有的传统机构知识库的不足之处。在此基础上,建立电机驱动型广义机构概念设计知识库。对于优选出的机构类型,配以应用实例。本知识库在广义机构概念设计的过程中,能有效地辅助机械功能原理方案的拟定,进行广义机构型综合,有效地支持产品的创新设计。 相似文献
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求解3-RPS并联机构刚度的新方法 总被引:9,自引:1,他引:8
对于少自由度机构来说,由于结构约束的存在,机构中出现了约束反力,约束反力会在机构中产生变形,影响整个机构的精度,在机构分析中必须加以考虑。基于此,以传统的3-RPS并联机构为例,给出考虑约束反力产生变形的刚度模型的建立方法。首先,用观察法分析该机构中存在的约束反力。其次,建立该机构的6×6形式雅可比矩阵,并运用虚功原理建立该机构的静力学模型。最后,分析机构在驱动力和约束力共同作用下产生的弹性变形。在约束反力产生的变形方向上虚设P副,将3-RPS机构的变形和刚度分析转化为一个等效的无约束反力的6自由度并联机构3-RPPS的变形和刚度分析。这种方法给少自由度机构的研究提供了一些新观点。 相似文献
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结合现有并联机构与柔索并联机构的特点,设计出一种刚柔结合的并联机构。在机构中加入柔索,达到提高机构精度、减小机构振动的目的。首先系统介绍了机构的构型,然后应用ADAMS仿真软件建立了并联机构的虚拟样机模型,进行了运动学仿真分析,证明了机构设计的合理性。 相似文献
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推导了凸轮数控磨床速度的计算公式,分析比较了恒线速度和恒角速度两种磨削方式的磨削参数,从而得出了恒线速度磨削优于恒角速度磨削的结论,为凸轮数控磨床速度程序设计提供了理论依据。 相似文献
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Generation of velocity profiles with speed limit of each axis for high-speed machining using look-ahead buffer 总被引:1,自引:0,他引:1
An efficient look-ahead algorithm to generate velocity profiles is presented in this paper. Algorithm allows for a nonzero
starting point velocity and end point velocity of every line segment to increase machining productivity. The paper considers
the intelligence of look-ahead to achieve faster machining speed, along with required accuracy. Speed limitation of a specific
axis and the direction change of an axis are newly added to the constraints of the velocity profile problem. This paper solves
graphically the problem of generating velocity profiles and derives the equations for representing the velocity profile. A
method to manage the look-ahead buffer is also proposed. To generate velocity profiles using the look-ahead buffer, three
phases are proposed. Phase 1 determines the velocity conditions such as the maximum velocity, starting point velocity and
end point velocity. In phase 2, velocity profiles are generated independently. Phase 3 handles the change of the start or
end point velocity. This phase 3 is repeated until all adjacent point velocities are the same. The proposed method was utilized
in the manufacturing field to engrave aluminum tire molds. It was demonstrated that this method contributes to an increase
of the machining accuracy and a reduction of the production time. 相似文献
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芯辊进给速度对环件冷轧工艺的影响规律 总被引:7,自引:0,他引:7
环件冷轧是一种先进的塑性加工工艺,而其中芯辊的进给速度对环件冷轧工艺有重要影响。本文针对环件冷轧工艺的特点,以数值仿真法为主要研究方法,以有限元分析软件ABAQUS为平台,利用弹塑性动态显式有限元法对环件冷轧变形过程进行了三维数值模拟,研究揭示了矩形截面环件开式冷轧工艺中总压下量不变时芯辊进给速度对轧制力、轧制力矩和环件轴向宽展的影响规律,并分析了进给速度与环件咬入之间的关系。结果表明:进给速度相对较小时,环件的宽展以及鱼尾形状系数随进给速度的增大而急剧减小,端面变得平整;当进给速度进一步增大时,环件宽展以及鱼尾形状系数变化不大;进给速度对鱼尾形状系数的影响主要取决于进给速度对环件外层附近金属的轴向流动的影响;随着芯辊进给速度的增大,轧制力和轧制力矩也相应增大,因此对轧环机力能参数的要求也提高;芯辊进给速度的增大不利于环件的咬入。 相似文献
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针对玻璃成形抛光中玻璃与抛光轮接触点相对线速度持续减小从而影响加工效率的问题,以控制相对线速度基本恒定、保证加工效率和精度为目标,提出基于三次NURBS曲线的速度控制算法。基于线性加减速方案,确定速度特性曲线控制点。结合Preston公式,以相对线速度基本恒定为约束条件,求解抛光轮中心末速度。以加加速度连续为约束条件,求取与控制点对应的权因子,确定抛光轮中心速度变化时的控制方程。采用四阶龙格-库塔数值方法确定插补初始点,再由米勒-汉明数值方法进行迭代校正,实现参数式曲线插补控制算法。试验结果表明,该速度控制方法能够有效保持玻璃与抛光轮接触点相对线速度基本恒定,加工效率较传统方法有较大提高。 相似文献
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This paper describes an electromagnetic flow meter for velocity profile measurement in single phase and multiphase flows with non-uniform axial velocity profiles. A Helmholtz coil is used to produce a near-uniform magnetic field orthogonal to both the flow direction and the plane of an electrode array mounted on the internal surface of a non-conducting pipe wall. Induced voltages acquired from the electrode array are related to the flow velocity distribution via variables known as ‘weight values’ which are calculated using finite element software. Matrix inversion is used to calculate the velocity distribution in the flow cross section from the induced voltages measured at the electrode array. This paper presents simulations and experimental results including, firstly the effects of the velocity profile on the electrical potential distribution, secondly the induced voltage distribution at the electrode pair locations, and thirdly the reconstructed velocity profile calculated using the weight values and the matrix inversion method mentioned above. The flow pipe cross-section is divided into a number of pixels and, in the simulations, the mean flow velocity in each of the pixels in single phase flow is calculated from the measured induced voltages. Reference velocity profiles that have been investigated in the simulations include a uniform velocity profile and a linear velocity profile. The results show good agreement between the reconstructed and reference velocity profiles. Experimental results are also presented for the reconstructed velocity profile of the continuous water phase in an inclined solids-in-water multiphase flow for which the axial water velocity distribution is highly non-uniform. The results presented in this paper are most relevant to flows in which variations in the axial flow velocity occur principally in a single direction. 相似文献
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计算了点到点运动控制中能量最优的速度轮廓——抛物线速度轮廓。分析了常用的梯形速度曲线和S型速度曲线。以S型速度曲线为参照对象,分析了三角函数型速度曲线和高阶多项式插值曲线的加速度以及加加速度的特性。 相似文献
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气象低速风洞参数及性能测试 总被引:2,自引:0,他引:2
通过对风洞不同风速段进行“频率—速度”参数拟合,校正了气象风洞的实验参数,并对风洞的风场气流均匀性及风速稳定性进行了测试.当风速相对较低时,整个风洞风场属于层流及缓冲层范畴,而在高风速下,风场属于湍流范畴.在0~1 m/s风速段,特别是在风速低于0.5 m/s时,风速变异系数C.V及风速相对偏差δ都达到了较高的水平,外界环境的变化对风洞风场的影响较大;而当风速在1~30m/s范围时,两个指标均相对较低,这说明随着风速的提高,风洞风场对外界环境变化的反映变得不敏感. 相似文献
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The influence of velocity gradients, in a laminar approach flow, on the local burning velocity was investigated, to supplement and verify recent theoretical work.Different velocity profiles were obtained at the exit from a circular burner, using pipes of different lengths between the exit and a settling chamber, and these profiles were measured using hot wire anemometry. The burning velocity and the velocity component parallel to the flame front were obtained by means of the “angle method” using direct photographs of the flame.The results, presented as burning velocity versus velocity gradient along the flame front, show that the local laminar burning velocity decreases as the rate of “stretching” of the flame is increased. 相似文献