An Analysis of the Orthogonal Crank-rocking Lever Spatial Mechanism for the Weft Insertion in Rapier Looms

On the basis of the analysis of typical orthogonal crankrocking lever spatial mechanism for the weft insertion in rapier looms, the rules of the outputting lever motion and the mechanism pressure-angle variety are studied when the maximum swing angle of rocking lever and the length of outputting lever have different values, and the optimum parameters suitable for motion transmission can be chosen. At the same time some existing shortpoints of the mechanism are also pointed out.

Kinematic Modeling and Characteristic Analysis of Eccentric Conjugate Non-circular Gear & Crank-Rocker & Gears Train Weft Insertion Mechanism

A novel weft insertion mechanism named eccentric conjugate non-circular gear & crank-rocker & gears train weft insertion mechanism was proposed in order to better meet the requirements of rapier loom's weft insertion mechanism as well as reduce the manufacturing difficulty. Meanwhile, based on the working principle of this mechanism, kinematical mathematic models of this mechanism were established and an aided analysis and simulation software was compiled. The influences of eccentricity ratio, deformation coefficient, and other important parameters on the kinematics characteristics of this mechanism were analyzed by using the software. A group of preferable parameters which could meet the requirements of weft insertion technology were obtained by means of human-computer interactive optimization method. The maximum velocity, maximum acceleration, and variation of acceleration of this mechanism are smaller than those of the conjugate cam weft insertion mechanism applied on TT96 rapier loom under the conditions of the same unilateral total stroke of rapier head and the same rotary speed of loom spindle; meanwhile the other demands of weaving technology can be met by this novel weft insertion mechanism.

An Optimization Design of a Weft Insertion Mechanism for Rapier Looms

By analyzing a combined and spatial 6-bar linkage weft insertion mechanism, its practical model for optimization design is set up and the modification of penalty strategy is put forward so that the genetic algorithm can be better used in optimization design for mechanisms with non- linear constraints. The design result is discussed.

Reverse Solution and Parametric Design of the Conjugate Cam Weft Insertion Mechanism Based on VB.NET and UG

In order to realize the parametric design of the conjugate cam weft insertion mechanism,according to the necessary parameters of weft insertion process,ideal kinematic curves of the weft insertion mechanism were given,and the mathematical model of reverse solution for this mechanism was established.The parameters of this mechanism were obtained by reverse solution on the basis of the given ideal kinematic curves and kinematic requirements.The parametric design platform which was integrated with the functions of parametric reverse solution,motion simulation,three-dimensional modeling and virtual assembly was developed based on VB.NET and Unigraphics(UG) NX.After entering the technological parameters of weft insertion process and essential structural parameters by users,three-dimensional drawing of the main parts such as the conjugate cam and shaft,can be obtained by this platform,also the processing data of the cam can be calculated.This platform provides a rapid approach for parametric design of weft insertion mechanism.

Reverse Design and Test of Non-circular Gear & Crank-Rocker & Gear Trains Weft Insertion Mechanism

For the purpose of obtaining satisfactory performance of the non-circular gear & crank-rocker & gear trains (NCCRG) weft insertion mechanism which was proposed in this paper, the ideal kinematic curve of this weft insertion mechanism was given, and the reverse solution models of this mechanism were established. A reverse design and simulation software was compiled based on Visual Basic 6.0 to obtain the mechanism parameters, including the pitch curves and tooth profiles of the non-circular gears. A test-bed of this mechanism was developed according to these parameters. The kinematic performance of this weft insertion mechanism was tested by high-speed video tape recorder with its corresponding video analytical software Blaster's MAS. And the test results were identical with the theoretical calculation. Compared with the conjugate cam weft insertion mechanism which is applied on TT96 rapier loom, under the condition of same weft insertion rate, the variation of acceleration of this mechanism is smaller. This novel weft insertion mechanism can meet the requirements of weft insertion on rapier looms with smooth and steady motion.

Simulation and Analysis of Spatial Weft Insertion Mechanism Considering Flexibility and Clearance

A 3D model of the spatial four-bar weft insertion mechanism was built with unigraphics NX(UG) according to the actual requirement,and dynamics simulation was carried out by importing the model into ADAMS.Without considering the clearance,the motion characteristic curve of the sword belt was generated through ADAMS combined with MATLAB.In this paper the hinge between the rod and the sector gear was selected as an example with different values of clearance,outputting the motion characteristic curve of the sword belt.Finite element analysis(FEA)was conducted,the flexible body was generated by importing the forked frame into ANSYS,and flexible dynamics simulation was carried out by importing the flexible body into ADAMS to replace the rigid rod.A comprehensive comparison of the output characteristics of the sword belt was conducted in the consideration of the clearance or flexible.Analysis of the force on the left hinge of the rod was carried out with the ADAMS post processing module.With the same clearance,considering the flexibility,amplitude of fluctuation of the force on the hinge increased obviously.

Dynamic Modeling of Variable Stiffness and Damping for Spatial Linkage Weft Insertion Mechanism with Clearance

In order to further analyze the influence of clearance on the kinematic performance of spatial linkage weft insertion mechanism,it is necessary to study the dynamic characteristics of contact impact force model with the variable stiffness and damping coefficient.Firstly,the parameters in the output process of the system are solved by describing of the flexible joint clearance.Then,based on Lankarani-Nikravesh contact force model,the contact impact stiffness and damping coefficient is modified from fixed values to time-varying coefficients.The dynamic model of spatial linkage weft insertion mechanism with modified clearance is established by Lagrange method,and the dynamic characteristics of the system are calculated.The results show that the joint clearance can directly affect the output performance of the mechanism.With the increase of the clearance value,the curve fluctuations of acceleration,driving torque and collision force are obvious,and it will be further intensified with the increase of spindle speed,which greatly affects the stability of mechanism and fabric quality.Finally,the virtual prototype is established by the SolidWorks software and simulated by the ADAMS software.The simulation results are compared with the numerical results,which verifies the accuracy of the modeling method in this paper.

空间连杆引纬机构的刚柔耦合磨损分析

为准确预测空间连杆引纬机构间隙磨损机制,通过结合Lankarani-Nikravesh与Bai碰撞力模型,建立可变刚度与阻尼系数非连续接触碰撞力模型,采用改进的Coulomb摩擦力模型描述含间隙机构旋转铰的切向摩擦力,通过Lagrange方法对系统动力学建模;其次选取空间连杆为柔性化对象,综合Ansys与Adams分析,对空间连杆引纬机构进行刚柔耦合动力学仿真;最后将系统的动态仿真响应结果与Archard模型相结合,求解运动副磨损情况。结果表明:柔性构件可以有效缓解机构间隙碰撞的冲击作用,间隙为0.15 mm条件下,剑头加速度振荡最大幅值缩减53.2%;当间隙升至0.5 mm后,虽磨损范围大幅增加,但间隙磨损深度并未随之大幅提升。

喷水引纬机构动态特性对自由射流的影响

为适应不同喷水引纬织机幅宽的需求,基于伯努利与液体连续性原理建立喷水引纬机构动力学模型,喷嘴自由射流初始段最大距离与纬纱所受射流牵引力的数值模型,分析其动态特性并通过弹簧刚度系数确定凸轮系统最低转速,探讨不同弹簧刚度系数与弹簧最大压缩量条件下机构动态特性对柱塞运动周期、射流最大速度、雷诺数、射流初始段最大距离、纬纱所受射流牵引力的影响;仿真结果表明:弹簧刚度系数增大时,柱塞运动周期变小,对应的凸轮系统最低转速变大,当弹簧最大压缩量取0.029 m,弹簧刚度系数取40 000、50 000、60 000 N/m时,水射流速度最大值为62.19、69.85、78.99 m/s,射流初始段最大距离为937、1 000、1 074 mm,纬纱所受水射流牵引力为5.37、6.44、7.28 N;而弹簧最大压缩量对上述变量的影响幅度很小,故在大幅宽织机需求下应首要考虑使用更大刚度系数的弹簧。

巴斯噶蜗线齿轮-曲柄滑块式引纬机构设计

为了优化引纬机构性能,在现有引纬机构的基础上进行了创新研究,提出了一种巴斯噶蜗线齿轮-曲柄滑块组合传动的新型引纬机构。为便于分析新型引纬机构的运动特性,基于数值分析和几何图形建立了该机构的运动学数学模型,并利用MatLab建立了该引纬机构的可视化设计分析平台。为分析各设计参数对该引纬机构的运动特性的影响,以剑带加速度为优化目标,利用正交试验优化方法对该机构进行优化分析,得出展长与发生圆直径比值、连杆长度与曲柄长度比值和传剑轮半径这3个参数对引纬运动规律有较大影响;变性系数和丝杠螺距则影响不大。研究结果可为全面研究引纬机构运动特性提供参考意见。

变导程螺旋引纬机构运动特性分析

为了研究曲柄滑块机构及变导程螺旋传动机构运动特性,采用平面解析法建立了曲柄滑块机构的运动学模型,并利用MatLab对其机构特性进行仿真。以标准椭圆比函数作为引纬运动规律,应用多项式拟合,建立了滑块位移与螺杆转角的函数方程,并推导出变导程螺杆的螺旋线方程、螺旋升角及导程的表达式;分析了螺旋传动的工作原理和影响螺旋传动效率的因素,将螺旋升角控制在合理的范围以提高螺旋传动效率;选择摩擦因数较小的螺旋副材料并配以合理的润滑方式。

衬纬复合材料经编机推纬机构的设计

为了开发双轴向衬纬经编机、研究其中推纬机构的设计方法,文章分析了推纬工艺过程,发现推纬针有最后、最前和最高3个关键点位置,前后和上下运动位移,以及相对应的主轴转角要求。选用平面五连杆执行机构与两组并行的平面多连杆机构串联,构成两自由度平面多连杆推纬机构;采用矢量方程参数法求得执行机构的两个运动输入摆角,并据此采用图解反转法综合出第一、第二推纬机构的尺度;对设计的推纬机构进行运动仿真,得到推纬针运动轨迹、3个关键点坐标和对应主轴转角大小,前后、上下运动位移分别为19、7.7 mm,关键点坐标、主轴转角的误差均小于±5%,满足设计及工程应用要求。

全幅衬纬针织物/沙林树脂柔性复合材料制备及弹道冲击性能

为平衡防弹材料自重、灵活性、舒适性与防弹性能之间的关系,以芳纶纤维全幅衬纬针织物为增强体、沙林树脂为基体材料,制备3种不同规格的柔性防弹复合材料。为探究全幅衬纬针织物/沙林树脂复合材料的弹道侵彻性能,对其进行不同速度下的弹道冲击测试,并采用XCT断层扫描探究复合材料内部的损伤扩展情况,分析其损伤机理及失效模式。结果表明:3种全幅衬纬针织物/沙林树脂复合材料的弹道极限速度分别为365.31,339.76和338.29 m/s;且在弹丸冲击作用下,复合材料迎弹面倾向于发生剪切破坏,背弹面倾向于发生拉伸破坏,复合材料具体损伤模式受到弹丸入射速度的影响。研究结果验证了全幅衬纬针织物增强复合材料在防弹领域的应用潜力。

椭圆齿轮—曲柄摇杆引纬机构的运动学建模与特性分析

为了分析椭圆齿轮—曲柄摇杆引纬机构的运动学特性,建立了该机构的运动学数学模型,开发了辅助分析软件,分析了一些重要参数对该机构运动学特性的影响,得到了一组较佳的参数。对该组参数下的引纬机构进行了运动分析,并和比利时PICANOL公司生产的GTM剑杆织机的空间四连杆引纬机构进行了比较,证明了椭圆齿轮-曲柄摇杆引纬机构能满足引纬要求。

非圆齿轮行星轮系引纬机构的反求设计与运动学分析

为了分析非圆齿轮行星轮系引纬机构的运动学特性并获得一组较优的参数,建立了该机构的运动学分析模型,基于Visual Basic 6.0平台编写了该机构的辅助分析与运动仿真软件,分析了几个重要参数对机构中非圆齿轮节曲线的影响,得到了一组较优的机构参数。对该组参数下的引纬机构进行运动仿真分析,在相同筘幅和织机主轴转速条件下,对非圆齿轮行星轮系引纬机构和TT96剑杆织机引纬机构的运动学特性进行了比较,结果表明非圆齿轮行星轮系引纬机构具有较小的最大速度值和最大加速度值,能够满足引纬要求。

基于改进NSGA-Π算法的新型引纬机构的参数优化

为了得到椭圆齿轮曲柄摇杆新型引纬机构的最佳参数,以剑头加速度变化最小和等腰梯形加速度规律为目标,以满足引纬工艺和机构运动性能要求为约束条件,建立了该机构的优化模型,该模型为高维带约束的非线性多目标优化模型。结合适应性不可行度和精英保留非劣排序遗传算法(NSGA-Π),提出改进优化算法,编写辅助优化程序,得到一组最佳参数,并对该组参数下的引纬机构进行运动分析和比较。结果表明该优化算法能有效地解决多目标非线性约束优化问题。

基于ANSYS和ADAMS空间四连杆引纬机构的柔性动力学仿真

针对空间四连杆引纬机构的引纬要求,用PROE建立该机构的三维实体模型,生成空间四连杆引纬机构的刚体模型,并选取叉形架作为柔性体,用ANSYS划分网格,生成中性文件,然后导入ADAMS中替换刚性叉形架进行柔性动力学联合仿真,最后将仿真生成的载荷文件添加到ANSYS叉形架中,对其进行应力分析。与刚性动力学仿真数据相比,柔性动力学仿真的位移和速度曲线平滑度好,但加速度曲线局部有波动。对叉形架进行的有限元应力分析显示3个连接点处应力最大。此研究结果可为引纬机构后续的优化设计提供参考。

碳纤维多层立体织机引纬机构振动动力学仿真

针对现有碳纤维立体织机引纬机构剑杆高速运动振动剧烈、运动稳定性不佳的弊端,以Adams平台为基础,建立立体织机引纬机构的动力学模型,根据Hertz接触理论来考虑齿轮齿条的动态啮合过程,对立体织机引纬机构采用正弦运动规律和修正梯形运动规律的动力学性能进行仿真对比分析.仿真分析结果表明:相比采用不同运动加速度规律,由于齿轮齿条啮合产生的啮合力冲击对引纬机构的振动影响更大,是剑杆产生振动的主要原因.

含间隙和尺寸误差空间连杆引纬机构运动精度综合分析

为分析间隙和尺寸误差对引纬机构运动精度的影响,详细介绍了非连续接触模型和等效杆长理论的使用方法,针对空间连杆引纬机构中的空间四杆机构和平面四杆机构,在考虑制造误差和磨损或装配间隙的情况下,以概率分析方法和非连续接触理论为基础建立了运动学模型。运用Mat Lab的计算和仿真模块进行运动仿真,得出了相关曲线。详尽分析了机构的尺寸误差和间隙对整个机构运动输出的影响,在考虑构件误差和间隙影响时,剑头的输出误差比单独考虑1种影响因素时明显,且误差最大值都出现在速度的极大值点附近,可见间隙和构件误差对高速机构的影响尤为显著,此研究结果可为后续对空间连杆引纬机构的运动精度分析提供参考。

剑杆织机空间连杆引纬机构载荷特性研究

为了研究剑杆织机空间连杆引纬机构对主轴产生的载荷的变化规律,运用Pro/E软件的机构分析功能,针对不同的空间连杆引纬机构,以主轴为等效构件,分析了引纬机构中各构件的等效转动惯量分布和变化规律,以及引纬机构的等效载荷等。研究结果表明:剑头、剑带、传剑轴的等效转动惯量占整个引纬机构的等效转动惯量的比例极大,而且随着门幅的加宽,所占比例增大;引纬机构的等效载荷主要来自于自身的惯性载荷。降低剑头、剑带及传剑轴的质量和转动惯量是高速织机发展的趋势。