基于齿轮传动系统横-扭-摆耦合非线性动力学模型的齿廓修形优化设计

基于齿轮传动系统动力学模型的齿廓修形优化设计可真实地反映修形参数对齿轮动态特性的影响。考虑几何偏心、陀螺力矩和齿向偏载力矩,建立了单级齿轮传动系统10自由度横-扭-摆耦合非线性动力学模型。提出了考虑齿轮实际运动状态并可适用于齿廓修形齿轮的啮合刚度模型,并采用解析法计算啮合刚度。为了降低齿轮传动系统的振动和噪声,以减小齿轮传动系统的动载系数为目标,建立了基于齿轮传动系统横-扭-摆耦合非线性动力学模型的齿廓修形优化模型。对某重载车辆齿轮传动系统进行了齿廓修形优化设计,优化结果有效的降低了齿轮的动载荷,可为设计低振动和低噪声的齿轮传动系统提供依据。     

基于OpenGL的双圆弧齿轮专用三维实体软件DAM的开发

在齿面接触强度和轮齿弯曲强度方面,双圆弧齿轮比渐开线齿轮高,但其几何设计和力学计算比较复杂.为了推广这种性能优异的齿轮,必须实现设计自动化．DAM软件正是针对这一目的开发的,它是基于OpenGL图形内核,集几何设计和力学计算乃至数控代码生成于一体的专业圆弧齿轮软件．限于篇幅,主要介绍几何设计部分．     

刨齿刀的三维可视化设计

三维参数化、可视化设计是现代机械设计的发展趋势之一。在AutoCAD软件的二次开发工具VBA(visual basic for application)中,开发了刨齿刀三维参数化和可视化设计软件。在AutoCAD软件中进行刨齿刀三维参数化建模,利用生成的刨齿刀三维实体模型,在Pro/Engineer,ANSYS软件中进行刨齿刀有限元分析。制造了硬齿面圆锥直齿轮刨齿刀,对刀具的磨损进行分析,为刀具的快速开发提供条件。     

基于VB的渐开线齿轮计算机辅助设计

齿轮是机械设计中应用最为广泛的零件之一,为了适应现代社会对产品需求的小批量、多品种以及更新换代快的特点,提高机械设计的效率。以Windows操作系统为平台,采用Visual Basic:6.0来开发渐开线齿轮的计算机辅助设计系统。可进行不同类型的齿轮传动的设计计算及强度校核,并输出符合设计要求和辅助条件的齿轮参数,提高了设计质量,大大减少了设计工作量。     

机械加工工艺实训系统的研究与实现

研究典型零件机械加工工艺的特点及经验知识,利用Visual Basic 6.0开发基于典型零件机械加工工艺实训系统。针对轴、箱体、齿轮、连杆四类典型零件建立工艺知识学习模块、工艺知识测试模块、典型工艺分析模块、典型工艺实训模块和管理模块。同时在典型工艺分析模块里还建立针对轴、箱体、齿轮、连杆四类典型零件常见机械加工表面的典型工艺知识库,通过交互界面的可视化设计,根据指定零件被加工表面的特点自动生成加工方案,针对指定零件进行工艺规程编写实训以及对数据库中的内容进行可视化管理。     

齿廓修形斜齿轮副啮合刚度解析计算模型

斜齿轮的轮齿误差是一个三维空间问题,其齿廓修形后啮合刚度的解析计算方法不同于直齿轮。改进了斜齿轮三维空间啮合线长度及位置计算方法,实现了斜齿轮啮合线长度及啮合位置的快速计算;根据力、变形分解原理和刚度/误差耦合关系,提出了一种考虑轴向变形以及齿廓修缘的斜齿轮啮合刚度解析计算模型;以一组斜齿轮副为例,研究了斜齿轮啮合刚度与啮合线长度在一个啮合周期内的变化规律,分析了不同齿廓修形参数对斜齿轮啮合刚度的影响规律。研究结果表明:利用该模型不仅可以准确快速地计算斜齿轮副啮合刚度,而且还可以确定最佳齿廓修形量,为斜齿轮的齿廓修形提供理论指导。     

立磨减速机斜齿轮副啮合性能分析及齿形优化

齿轮运转过程中,偏载会影响齿面啮合性能,降低齿轮的寿命,因此,需要减小偏载带来的不利影响.利用Romax软件的微观几何设计功能,以传动误差的波动值最小为目标函数,以齿廓的修缘量和起始角、齿向的偏斜和鼓形量为设计变量,对立磨减速机平行级斜齿轮副的修形参数进行优化,以寻找最佳修形量.对比发现,修形后齿轮副的传动误差、单位长度的法向载荷、最大接触应力以及轮齿所受载荷均有较大改善,优化效果较为明显.齿轮微观几何设计可有效解决偏载,改善轮齿的啮合性能,提高传动的平稳性.     

基于CATIA工程斜齿圆柱齿轮精确建模与失效有限元分析

以准确绘制齿廓渐开线和螺旋线为基础,通过多截面曲面绘制出齿型曲面并运用曲面缝合功能实现齿型闭合,最后结合技术细化处理,实现斜齿轮的精确建模．在此基础上,利用CATIA软件CAE功能并结合斜齿轮传动原理,对斜齿轮实际工况进行有限元分析,从而为工程失效分析提供精确的数据参考．     

一种改进的齿轮非线性动力学模型

在考虑齿面摩擦、齿轮时变啮合刚度和齿侧间隙的情况下,推导出了改正的齿轮副系统的非线性动力学模型,应用符号运算软件,编写符号运算程序,得到了齿轮副非线性振动微分方程。该模型在计算摩擦力时,考虑了载荷在啮合区的动态分配,并根据啮合区单双齿交替的特点提出用周期扩大法建立摩擦力、齿轮时变刚度的模型,改正的齿轮非线性动力学模型是一个周期系数分段线性的非自治系统,与以前所建立的模型相比,该模型的参变系数是具有相同周期的周期函数,新的齿轮非线性动力学模型的建立为求解时变的齿轮动力学方程近似解析解带来方便。     

基于OpenGL的渐开线弧齿锥齿轮三维参数化建模

 通过对渐开线弧齿锥齿轮研究,以齿廓啮合定律为出发点,提出一种与加工方法无关的弧齿锥齿轮的精确建模方法.以此理论为依据,开发了一种基于OpenGL图形内核,集几何设计﹑动态仿真和力学计算于一体的弧齿锥齿轮专用建模软件,通过便捷的参数输入,自动完成渐开线弧齿锥齿轮的三维实体造型.且在建模过程中直接利用方程建立球面渐开线,从而保证了齿形的准确性,为后续直齿锥齿轮的有限元力学计算提供了精确的模型.     

螺旋锥齿轮球面渐开线齿面形成原理及推论

从螺旋锥齿轮的精确齿面形状出发,详细地论述了球面渐开线齿面的基本组成。基于球面渐开线理论在螺旋锥齿轮方面已取得的研究成果,分析并总结其特点与不足,提出了螺旋锥齿轮的球面渐开线齿面形成原理。并对球面渐开线齿面形成过程中的关键环节产形线、工作齿廓和球面渐开线齿面的基本方程进行了推导和论述,为其设计及加工提出了一些方案,以便为螺旋锥齿轮的研究提供理论基础和思路。     

球面渐开线齿形的螺旋锥齿轮NURBS设计

 为避免传统设计和加工的近似球面渐开线齿形螺旋锥齿轮存在的缺陷,提出了一种新型螺旋锥齿轮设计方案．从齿面精确组成和形状特征出发,将球面渐开线理论应用于齿面基本曲线的方程表达式求导中,实现了齿面曲线的分段参数化．然后,对组成齿面的各区域分别求取齿面离散点数据,并采用三次均匀B样条曲面方法进行初步的拟合与拼接．为了进一步提高齿面精度,借助NURBS方法对拼接后的齿面进行了统一的NURBS精确拟合,并给出了齿面统一参数化的优化方法．最后的算例表明了相关方法的精确性和可行性,为螺旋锥齿轮的数字化设计与NURBS加工提供了新的思路与途径．     

基于接触应力优化的摆线轮修形设计

对摆线轮进行合理的修形能够极大改善RV（rotary vector,旋转矢量）减速器的传动性能和承载能力。为了进一步优化“反弓”齿廓的接触应力,在综合分析组合修形对反弓齿廓啮合力和接触应力的影响的基础上,提出了一种两段修形方法。该方法是将摆线轮齿廓分成2段,并根据需要对不同工作段的齿廓采用不同的修形量,以更灵活地设计摆线轮的齿廓。以RV-40E减速器为例,先利用MATLAB软件建立摆线轮受力分析模型,并按照两段修形方法确定新齿廓的修形量和方程;再利用ANSYS软件建立摆线轮与针齿接触的有限元模型,并对比新齿廓与反弓齿廓的接触应力。理论计算结果显示,新齿廓的最大接触应力降低了8.34%;有限元仿真结果显示,新齿廓的最大接触应力降低了4.39%,并分析了可能的误差来源。研究表明,两段修形方法可以改善摆线轮齿廓的接触应力和延长摆线轮的使用寿命,这为摆线轮的修形设计提供了一定的参考。     

非圆齿轮三维造型设计系统的开发

基于非圆形节曲线的非圆齿轮设计和计算要比圆齿轮复杂得多。由于非圆齿轮各轮齿的形状不尽相同,因此无法使用阵列、镜像等方法进行建模。目前的三维机械CAD软件还不能直接进行非圆齿轮实体建模。文章利用Visual Basic语言对三维软件SolidEdge进行二次开发,实现了齿轮的根切校验、凸性校验、压力角计算等功能,建立了非圆齿轮的三维建模系统,为非圆齿轮三维建模参数化设计提供了一种方法。生成的齿轮三维实体可用于装配设计、运动仿真及计算机辅助教学中。     

Design systems for gear elements made of cotton fiber-reinforced plastics

We look on the cotton fiber reinforced plastics as industrial gear materials, and have been developing design systems for industrial gears made of cotton fiber-reinforced plastics. In this report, we deal with a method estimating for tooth root stresses caused by bending movements under running conditions. The gear material used was cotton fiber plain woven cloth reinforced phenolic resin laminates. Paper-reinforced phenolic resin laminates, a commonly used material, was used as a control for comparison. The main dimensions of the gears were module 3–5 mm and tooth width 25 mm. First, accelerations of gears were measured under running conditions to estimate dynamic performance. Second, fracture tests of gear teeth were carried out under bending loads. Different fracture modes at tooth roots for cotton fiber-reinforced plastics and phenolic resin gears were observed. The fractures occurred at a high position from the tooth root in the case of the cotton fiber-reinforced plastics gear because the cotton fiber-reinforced plastics had excellent cleavage and shear strength. This gear also had higher strength for tooth bending loads. Third, the mechanical properties of the gears were researched by tensile, bending, and shearing tests. It was clear that the cotton fiber-reinforced plastics had excellent properties in cleavage fracture between laminates and shear strength. Finally, we proposed a design method for this gear, which considers the cleavage and shear strength.     

Quantitative evaluation of safety-critical software at the early development stage: an interposing logic system software example

In order to produce highly reliable software, designers and developers pay particular attention to the early development phases, that is, the requirement phase and the design phase. In this work, a few novel quantitative measures are suggested for estimating how much influence the development methods at the early stage have on the reliability elevation. Three complexity measures are suggested in this work, which are Operation Complexity, Interface Complexity, and Micro-Complexity. These measures are based on the entropy concept. The entropy-based complexities need information on probability distributions. For this purpose, the operational profile for Operation Complexity, the relative frequencies of module couplings for Interface Complexity, and the relative frequencies of module strengths for Micro-Complexity are introduced.

We further developed estimation standards for these complexities. In order to demonstrate the utility of these standards, the software design of a digital Interposing Logic System (ILS) of an Engineered Safety Feature Actuation System (ESFAS) in nuclear power plants has been evaluated using the standards presented in this work. The results show that the proposed standards are useful in developing more reliable softwares and minimizing the efforts or costs for coding, testing, etc.     

直齿圆柱齿轮双向镦挤精密成形工艺对比研究

为实现直齿圆柱齿轮精密成形,并克服传统工艺存在的成形力大、模具结构复杂等一些不足,在已有齿形凸模双向镦挤成形直齿圆柱齿轮的基础上提出了另外2种改进的成形工艺,分析了不同成形工艺下端面摩擦力对载荷的影响,利用有限元模拟软件DEFORM-3D分别对3种成形工艺进行了数值模拟研究,并提出了一种优化的成形新工艺——无齿凸模双向镦挤精密成形.结果表明:采用无齿凸模镦挤成形直齿圆柱齿轮在载荷及模具结构方面优于有齿凸模镦挤成形,其中,无齿凸模双向镦挤较有齿凸模双向镦挤,上、下凸模载荷下降约55%;无齿凸模双向镦挤较非对称凸模双向镦挤,上、下凸模载荷分别下降约50%、38%;无齿模具加工制造更容易,强度更高;新工艺的等效应力最大值为3种方案中最小,而且等效应力变化正常,无破坏现象出现.对优化后的成形工艺进行了试验研究,得到了齿形轮廓清晰、充填饱满、无折叠、开裂等缺陷的铅质试件,试验结果与模拟结果基本吻合.     

Effect of the load location along the involute curve of spur gears on the applied stress at the fillet radius

In this study, attempts are carried out to determine the amount of stress at the fillet radius region of spur gears when the applied load location changes, along the involute curve, from the top surface to the bottom. For this purpose the photoelastic method and numerical MSC/NASTRAN software are used. The gears with pressure angle (ϕ) 20^o, and 25^o were prepared from photoelastic material type PLM‐4B in this study. Practical calibration is used to determine the fringe order value of this material. Four different modules (m); 6, 10, 14, and 20 mm were prepared for two different numbers of teeth (N); 18 and 26, with different face widths (B₁, B₂, B₃); 10, 17, 25.4 mm respectively. Four load values were applied on each tooth at five to six different load locations along the involutes curve profile. In order to accomplish the comparison between the results for different methods, the same sample dimensions and parameters were prepared again for the MSC/NASTRAN software. The results showed that the maximum applied stress at the fillet radius occur when the applied load location is on the top land of a tooth, and then that amount is decreased when the applied load positions change toward the bottom land. The results of the NASTRAN method showed that the applied stress at the fillet radius would be minimum when the loading point locates between the pitch circle and dedendum circle, in particular around 1.5 times module (1.5 m) of the total tooth height which equals 2.25 module, and then the applied stresses are increased again. However, in the photoelastic method the applied stresses were decreased continuously to the bottom land. The reasons behind such results can be attributed to the type of failure theories that can be used in NASTRAN software for characterization the applied stresses, i.e. considering types of applied stresses into account, such as bending, direct compressive, and shear stresses. Moreover, in order to compare the applied stress values at fillet regions, obtained by theoretical and practical approaches, four different standard mathematical equations are used for stress calculation at fillet radius of spur gears to show the difference of the parameters and variables that can affect the applied stress results.     

基于RTLinux的模块化、网络化开放式控制器系统

现代开放式控制系统追求方便的扩展、灵活的定制、容易的移植和无缝的集成等特性。本文提出了一种基于RTLinux的开放式控制器系统(RTOC)。文章首先提出一种包含硬件平台、操作系统模块和应用软件模块的参考模型。然后,在实时操作系统RTLinux上开发完成了RTOC。由于RTLinux操作系统平台的开放性,在RTOC中,应用软件模块和操作系统模块都可以被轻松地扩展与定制。同时由于核心部分采用标准C语言进行开发,加之：RTLinux本身具有良好的可移植性,RTOC的软件部分能够很容易地移植到其它硬件平台上。为了保证模块之间的无缝连接,RTOC中实现了基于文件系统的通讯方法和硬件无关访问接口。整个系统采用层次化、模块化的设计,结构清晰,便于二次开发。同时由于RTLinux的支持和RTOC系统设计的优势,本系统具有明显的网络化特征。在RTOC执行控制任务时,关键任务会被加载到系统的核心态运行,从而保证了实时性能。最后,RTOC系统被成功地应用于虚拟漫游平台的控制试验中,证明了其具有良好开放性的优势。