Matlab在钣金展开中的应用

针对钣金展开中的积分运算问题,提出了应用Matlab软件解决问题的方法.并以椭圆柱面这一较为复杂的可展曲面为例,在建立展开数学模型的基础上,编程实现了钣金展开图的自动化参数化绘制,从而为数控切割和焊接创造了条件.     

可展开固体反射面天线折展机构设计及分析

针对传统固面可展开天线中旁瓣绕双转轴独立折展造成的系统同步性差及可靠性低的问题，设计并分析了一种单自由度折展方案。首先提出了基于粒子群算法的收拢态位姿确定算法，结合等效轴角定理给出了单自由度旋转展开的参数确定方案；以相邻旁瓣运动轨迹为基础，结合变密度拓扑优化方法给出了反射器背架设计方案，分析结果表明本文所设计背架可使反射器热变形降低62.5%，基频提高了4倍，充分证明了背架设计的有效性。以一款10 m口径固面可展开天线为对象进行了折展机构设计，并分析了折展过程中运动学、动力学参数变化规律。基于螺旋理论对折展机构进行分析，得出了多种消极运动副引入方案，并最终选取RSPRR进行机构非过约束设计。分析结果表明，本文所述的固面可展开天线可以完成收拢态与展开态之间的切换，收纳率达到了0.384，折展过程平稳可靠，验证了该设计方案的可行性。同时，相关研究方法及结论可以为固面可展开天线的设计提供技术参考。     

基于工程条件构造可展面的方法

提出应用单参数平面族包络构造可展面的理论与方法,相应给出按照已知工程条件构造可展面的3种方法:已知可展面上一条曲线及可展面在曲线上的法线构造可展面;过两条已知曲线构造可展面;过已知曲线且与已知曲面相切构造可展面。     

复杂曲面的可展化及其展开方法

提出了一种复杂曲面可展化及其展开的新方法 ,在依附于复杂曲面的两条空间曲线之间 ,构造可展面 ,逼近复杂曲面 ,使复杂曲面可展化并展开。该方法以计算机辅助服装原型设计过程中的前片服装原型的可展化及其展开作为应用实例 ,证明其完全附和工业设计实际要求     

可展面的连接与组合

探讨了可展面连接的两种类型:相交连接与相切连接。通过定理论证,得出重要结论:两个可展面只有在直母线上才能实现相切的接触。该结论为服装设计及其它工程领域构造组合式可展面问题的解决提供了理论依据。     

基于空间可展机构可靠性设计分析

空间可展机构具有展开性能好、稳定性高、可延展性的特点,可适用于太阳能帆板展开机构、太空平面反射天线等领域,空间可展机构在展开和折叠时需要满足高精度、重量轻的要求,需要进一步对其进行模型设计分析与研究。为提高空间可展机构在展开和折叠时的运动精度,基于空间可展机构的杆件尺寸误差、装配误差和主动件角速度周期性波动误差的情况下,利用常规设计方法和可靠性设计方法分别对空间可展机构的驱动杆直径进行设计计算。结果表明：利用可靠性设计方法计算不仅可以起到优化杆件作用,还提高了可展机构的可靠度,验证了可靠性设计对于研究空间可展机构的可行性与有效性,同时对推进空间可展机构的工程应用具有一定的基础理论支撑与实际价值。     

径射状空间可展天线展开过程的智能控制研究

从多体动力学的角度建立径射状桁架可展开天线展开动力学方程,针对系统展开过程中动力学模型的非线性与时变性,基于神经网络设计出了一种具有预测与实时优化功能的过程控制系统,为可展天线展开过程速度控制提供了一种智能控制方法。仿真结果表明,该智能控制系统解决了空间可展天线展开过程中的复杂多变量非线性时变控制问题,并且具有良好的控制精度、自适应性、稳定性和鲁棒性。     

被动输入过约束四面体可展天线机构动力学分析

建立了一种由3RR-3RRR四面体单元组成的被动输入过约束可展天线机构的动力学模型,分析了驱动元件(扭簧)的数量、刚度、初始压缩量对机构展开运动的影响。基于3RR-3RRR四面体单元组成的可展机构的结构特点和空间坐标变换关系建立了机构展开/收拢过程中各构件质心位置与机构展开角之间的关系,得到了各构件的速度解析表达式。根据机构自由度性质,将机构展开/收拢过程中构件的运动分为平移运动、定轴转动、平面运动和复合运动四类。为便于建立3RR-3RRR四面体单元组成的被动输入过约束可展机构的动力学模型,进一步将构件的复合运动分解为平面运动和沿该平面法线方向的平移运动。基于拉格朗日法建立了单元可展机构3RR-3RRR和组合可展机构3(3RR-3RRR)-3RRR-3RRR的动力学模型,得到了机构中扭簧刚度与机构展开角之间的表达式,并讨论了扭簧刚度和数量对机构展开运动的影响。基于ADAMS仿真软件建立了3(3RR-3RRR)-3RRR-3RRR被动输入过约束可展机构的仿真模型,通过添加不同数量、不同刚度的扭簧对机构进行了动力学仿真分析,并讨论了扭簧初始压缩量对机构展开运动的影响,仿真结果验证了理论分析的正确性。研究结果可为由3RR-3RRR四面体单元组成的大型被动输入过约束可展天线机构的协调控制提供理论指导作用。     

模块化构架式空间可展天线支撑桁架展开精度测量与分析

为研究金属网面式可展天线支撑桁架对反射器表面形面精度的影响,开展模块化构架式空间可展天线支撑桁架展开精度测量试验及分析研究,根据支撑桁架的结构特点,基于机器人学基本理论,建立关键节点空间数学模型,设计悬吊随动式微重力展开试验装置,采用数字近景摄影测量原理,对支撑桁架的展开精度进行测量试验,并从支撑桁架的形面精度、重复展开精度和关键节点误差等3个方面进行分析。试验结果表明:支撑桁架上关键节点的均方根误差(RMSE)值较小,由关键节点构成的曲面其形面精度较高;支撑桁架在多次重复展开试验中,关键节点中最大误差小于1 mm,结构展开的一致性较好;完全展开后,关键节点的实测值与理论值接近,支撑桁架的制造及安装精度较高。提出的测量和分析方法为其他类型金属网面式可展天线支撑桁架展开精度的研究提供了借鉴和参考。     

可展收抛物柱面天线机构的设计及分析

可展收抛物柱面天线可用于卫星系统中,实现无线通信、深空探测以及空间目标搜索等功能。近年来随着航天事业的迅猛发展,对空间可展天线的成形精度要求越来越高。提出并设计了一种可展收抛物柱面天线机构,该机构主要由网面支撑机构、柔索、金属丝网、轴向驱动与锁定装置、径向驱动与定位锁定装置组成。其中,网面支撑机构包括径向和轴向展收机构。研究中提出了一种新型平面可展收机构作为径向展收机构的组成单元实现天线的径向展开收拢。对可展收机构的等效机构进行了优化设计。利用剪式单元可展机构实现了轴向展收机构的设计。完成了可展收抛物柱面天线机构的驱动组件设计,在Solidworks中完成建模,对天线机构进行了运动学仿真。     

螺旋曲面误差评定软件研制

螺旋曲面误差评定软件研制是一项系统工程,涉及到测点布置方法、测点数量与误差关系、螺旋曲面拟合、重构模型和标准模型匹配、误差评定、软件功能规划、软件工具选择、软件编制等内容。利用螺杆实例的初步验证,说明本软件的基本思路是正确可行的。     

变截面螺旋曲面的解析几何建模与CAD绘图

扫描变换法和路径拉伸法通常用于螺旋弹簧的近似造型,通过分析比较,指出了两种方法的不足之处.运用解析几何方法,研究了圆截面螺旋曲面的建模方法,并建立了各种截面形状的螺旋曲面通用解析表达式.同时,进一步研究了变截面螺旋曲面的形成与建模方法,并在AutoCAD中给出了基于VisualLISP的各种截面形状螺旋面的CAD绘图技巧.结果表明,此建模方法能大大提高螺旋曲面造型的精确度.     

A study on helical surface generated by the primary peripheral surfaces of ring tool

Often in the engineering practice, cutting tools bounded by primary peripheral surfaces of revolution are used because of their effectiveness. Among these, ring and tangential tools can be used for the generation of constant pitch cylindrical helical surfaces. In this paper, we present an algorithm for the profiling of these types of tools. The algorithm is based on the topological representation of the tool’s primary peripheral surface. The main goal is to devise a methodology for the profiling of tools whose surfaces are reciprocally enveloping with cylindrical helical surfaces. We present a numerical example for the numerical determination of the axial section form for this type of tools. The application method for this algorithm was developed in the CATIA graphical design environment within which the procedure is developed as a vertical application. In addition, we present a solution for the shape correction of the tool’s axial cross-section by considering the existence of singular points on the profile of the helical surface to be generated where multiple normals to the surface exist.     

Modeling and numerical simulation for the machining of helical surface profiles on cutting tools

The classical conjugation and envelope method is very accurate and effective for forward and inverse calculations of grinding helical surfaces. However, this method involves complicated mathematics and requires that the profiles be continuous. It can also result in undercutting or interference to the desired surface profiles. In this paper, a new approach is proposed to simulate the grinding process of helical surfaces on cutting tools. The paper begins with the reconstruction of cutter helicoids from sampled points. Using the recovered helical parameters from the sample points, the cross-sectional profile of the cutter surface is derived using a polynomial curve. A numerical method for calculating the profile of the grinding wheel required for the cutter surface profile is then provided. Finally, an optimization method is presented for solving the problem of inverse calculation to determine the helical surface profile for a given grinding wheel profile and setting parameters. The feasibility of the approach is tested by simulation results, which shows that the proposed approach can eliminate undesired tool-work interferences and undercutting.     

The profiling of end mill and planing tools to generate helical surfaces known by sampled points

Generation of helical surfaces with cylinder-frontal tools (end mill tool or grinding wheels) as so as with cylindrical tools (planing tools) are proceedings used in the small lot productions manufacturing or for reparations. In many situations, the surfaces to be generated are known by measuring on three-dimensional measuring machines. In this way, is possible to define a generatrix expressed by sampled points, which impose specifically algorithms for the end mill tool’s profiling. In this paper, specifically proposed are algorithms for end mill tool and planing tool profiling, designated to generate helical surfaces known in discrete form. More is assumed that the helical surface’s generatrix may be expressed only by few points, three or four, so the helical surfaces generatrix may be expressed by inferior degree Bezier polynomials using topological geometry. One of the goals of this paper is to compare the numerical results obtained by the proposed algorithm with the results obtained from profiling theoretically methods, for the same surfaces types, in order to proof the new method quality.     

Reduction of power and lubricant oil consumption in milling process using a new SiO2 nanolubrication system

In this paper, we propose a method based on the surfaces enveloping theory developed as a vertical application in the CATIA graphical design environment. This method is created for profiling tools intended to generate cylindrical helical surfaces with constant pitch. The devised method is applicable for the profiling of disc tools which are bounded by a primary peripheral surface of revolution. A few examples for the determination of the tool’s 3D primary peripheral surface are presented such as helical flutes of cutting tools, worms with wide pitches, and gear involute flanks. The results are presented in both graphical and tabular form for completeness. Screen snapshots of the CATIA-based vertical application are also shown.     

Determining Worm-Mill Profiles

The proposed mathematical model permits shaping of worm mills for the machining of parts with helical surfaces. The model includes a module generating matrices for the spatial transformation of coordinate systems. An algorithm is presented for formulating a model of the worm-mill surface. Shaping is completed in one stage, without determining the profile of the conjugate helical rack.     

3D graphical method for profiling gear hob tools

This paper approaches the issue of profiling gear hob bounded by a cylindrical helical surface with constant pitch, reciprocally enveloping with an ordered surfaces curl. The process kinematics of generation reproduces the 3D gear between the worm and the wheel. This gear has crossing axes and it is used for the profiling of the primary peripheral surface of the gear hub in the intermediary surface method (the common rack-gear of the surfaces curl to be generated and the primary peripheral surface of the gear hob). An algorithm in the CATIA design environment is presented, based onto an original method for the determination of the reference rack-gear form—the rack-gear reciprocally enveloping with the surfaces curl, using the principle of the cylindrical helical motion decomposition in translation and rotation motions. Graphical and analytical profiling examples are presented for the gear hob for generation of a parallel spline shaft and for the generation of a toothed wheel with involute teeth. Solutions for the interference problems, problems due to the singular points onto the profiles, are presented.     

均匀啮合间隙的合理性分析

从一般螺旋曲面的基本理论出发 ,论证了通常采用的均匀的啮合间隙对传统的渐开线螺旋曲面是合理的 ,但对具有复杂端面齿形的螺旋曲面如双螺杆压缩机的转子齿面则不合理 ,应避免使用