无侧隙双滚子包络环面蜗杆传动的参数优化

无侧隙双滚子包络环面蜗杆传动是一种能同时满足高精度、大载荷要求的新型环面蜗杆传动.为获得啮合性能优良的无侧隙双滚子包络环面蜗杆传动,提出综合考虑传动齿面接触性能和润滑性能对该新型传动的几何参数进行优选.通过对蜗杆副齿面啮合参数如诱导法曲率、卷吸速度、润滑角以及滚子自转角等的数值计算,分析表征传动啮合性能的齿面接触参数的影响因素,进而确定该新型蜗杆传动优化设计变量的取值范围.以此为基础,建立以蜗杆副的滚子自转角及齿面综合系数为优化目标,建立以传动齿面润滑角、蜗杆轴的强度与刚度以及几何不干涉等为约束的优化设计数学模型,并用Matlab的遗传算法工具箱对数值算例进行求解.数值实例表明,经过几何参数优化的蜗杆传动,其齿面接触性能和润滑性能明显得到改善和提高.     

Stability of fiber trajectories for winding toroidal pressure vessels

In this paper the fiber trajectory stability of filament wound toroidal pressure vessels is evaluated for two most frequently used patterns: single helical winding, helical and hoop winding. The basic equations of equilibrium for fibers on a torus are given based on netting analysis. The governing equations that determine helical winding angles along the meridional direction are derived for the two winding patterns. The slippage coefficients of the obtained fiber trajectories are calculated using the non-geodesic law and differential geometry. The condition between the hoop-to-helical thickness ratio and the relative bend radius of the toroid is also formulated to prevent fiber bridging on the concave surface. The fiber slippage and bridging tendencies are outlined and compared, corresponding to various relative bend radii and hoop-to-helical thickness ratios. The results show that the single helical winding process provides better stability of fiber trajectories, in terms of both fiber slippage and bridging, than the helical and hoop winding. The toroidal vessel with larger relative bend radius requires lower coefficient of friction between the fiber bundle and the supporting surface. The present analysis for fiber trajectory stability affords a useful reference tool for designing filament-wound toroidal pressure vessels.     

微机选配机床挂轮

利用微机选配挂轮,可以快速、准确地选配出在机床备用挂轮限制下的传动比精度最高的挂轮组合,并进行齿轮啮合性校核,实现机床挂轮的优化组合。     

双螺杆中啮合块、螺杆元件混合过程及混合性能的研究

以双螺杆挤出机中的啮合块、螺杆元件作为研究对象,对其混合过程及混合性能进行研究,分析物料与添加剂的相互运动及变化过程。利用网格重叠技术和Ployflow软件对啮合块、螺杆元件的混合性能进行仿真,研究螺杆元件及不同转速下啮合块对应流体区域内的最大剪切应力,粒子在流体区域内的停留时间分布、分布指数、分离尺度等。结果表明:在啮合块流道内的混合过程中,啮合区域的两种粒子进行分布混合,其他区域的粒子在轴向运动到第2片啮合块时开始被带入啮合区,与另一种粒子进行分布混合;在相同转速下,啮合块的混合性能优于螺杆元件,随着转速的提高,啮合块的分散混合性能逐渐增强。     

磁性超环面行星蜗杆传动的啮合原理研究

以超环面传动理论为基础,结合磁性传动理论知识,研究讨论了新型传动机构—磁性超环面行星蜗杆传动的啮合原理,介绍了该传动的基本结构、传动原理及参数关系,分连续啮合和间断啮合两种情况,研究了各构件间的啮合,得到了在不同情况下该机构正确啮合的啮合条件;在此基础上,研究分析了不同情况时的啮合齿数计算,得到了各种情况下的啮合齿数计算公式;分析了行星轮与蜗杆、行星轮与定子啮合的受力情况。项研究为该种传动的设计加工提供了理论基础。     

织物模拟中的自适应网格剖分研究

本文提出一种在织物模拟中的动态网格剖分方法,针对传统模拟算法中因网格剖分固定和曲面整体网格均匀剖分造成模拟误差与计算耗费,分别从织物物理和几何角度出发,提出在动态模拟过程中的自适应的网格剖分方法。利用模拟过程中曲面片局部形变信息,对网格进行动态剖分与合并,有效提高了模拟效率。经实际应用表明：该算法具有模拟效率高、易于计算机实现等优点,特别在对非均匀形变物体模拟中,该算法从模拟效率和精度均得到满意结果。     

计时仪器中渐开线齿轮啮合过程的分析

本文在考虑齿轮有加工误差，并有龆轮切点参与啮合的前提下，按进、出啮点位置的不同，把应用于计时仪器中的渐开线齿轮的啮合过程分成２类５种不同的工作过程，推导出了各种工作过程的进、出啮角的计算公式和具体工作过程的判别准则。     

共轭曲面的界函数 Φ_t、Ψ 和矢量、与啮合性能的关系

共轭曲面的两类界函数Φｔ、Ψ和矢量ｐ→、ｑ→反映了共轭曲面的内在特征和啮合性能。本文探讨了它们的物理意义及其与啮合性能的关系。     

微线段齿廓的形成原理及特性

介绍了微线段齿廓的形成原理,推导出了其齿条及齿轮的齿廓曲线方程,证明了该齿廓满足啮合基本定律且在啮合时有很多点的综合曲率为零,因而该齿廓有较好的啮合特性。根据齿廓曲线的计算公式,设计出了一个齿轮,并给出了部分数据和齿廓图形。     

Variational implicit surface meshing

In this paper, we propose a new algorithm to mesh implicit surfaces which produces meshes both with a good triangle aspect ratio as well as a good approximation quality. The number of vertices of the output mesh is defined by the end-user. For this goal, we perform a two-stage processing: an initialization step followed by an iterative optimization step. The initialization step consists in capturing the surface topology and allocating the vertex budget. The optimization algorithm is based on a variational vertices relaxation and triangulation update. In addition a gradation parameter can be defined to adapt the mesh sampling to the curvature of the implicit surface. We demonstrate the efficiency of the approach on synthetic models as well as real-world acquired data, and provide comparisons with previous approaches.