机械专业文献综述

机械专业文献综述
机械专业文献综述

文献综述

齿轮作为传递运动和动力的基础元件,在工业发展的历程中,发挥了十分重要的作用。它在机械传动中的地位是其它元件一直都无法替代的。随着现代科学技术的发展,齿轮技术有了很大的进步,它的方方面面都在产生着巨大的变化。例如,在设计上,基于动态弹性啮合理论的齿轮动态设计将取代基于刚性力学的静态设计;在加工上,齿轮加工机床及刀具的原始精度正在不断地提高;在检测上,齿轮测量技术正朝着高效率、高精度、多功能和智能化的方向发展;等等。

齿轮以其形状复杂而著称于世,其各项误差的检验项目种类繁多,并且技术上难度较大,是近一个世纪以来工程界最为关注的一项课题。我国精密测量技术和仪器的现状仍然远远不能满足国内机械装备制造业迅速发展的需求,尤其是在先进测量技术和仪器的基础理论研究、共性关键技术的开发方面与国外的差距越来越大。因此,齿轮测量的发展尤其是复杂齿轮测量的发展必然受到很大的限制。随着我国经济、技术与世界接轨,测量检测行业受到国外先进技术的冲击,其竞争能力也就必须加强。

目前国外发展了一些齿轮测量智能化仪器,但其价格昂贵,使用维修的技术性很强,所以大多企业还是沿用传统的齿轮测量仪器或通用仪器进行齿轮测量。这些仪器的电气控制及数据处理部分可靠性差、故障频繁,直接影响齿轮生产和新产品开发。为了缓解这种高新科技与落后环境的矛盾,低成本地提高我国几何量检测的智能化程度,用微机技术对该仪器升级改造、实现检测系统智能化很有必要。

研究真正反映齿轮三维几何空间形状和制造误差组成因素的齿轮整体检测方法在我国具有积极的现实意义,特别是研究用检测简便、精确、迅速的测量方法改造现有测量机更为突出。

20世纪80年代以前,齿轮测量原理主要以比较测量为主,其实质是相对测量。具体方式有两种:一是将被测齿轮与一个标准齿轮进行实物比较,从而得到各项误差;二是展成测量法,就是将仪器的运动机构形成的标准特征线与被测齿轮的实际特征线作比较,确定相应误差。而精确的展成运动是借助一些精密机构来实现的,不同的特征线需要不同的展成机构。比较测量的主要缺点是:测量精度依赖于标准件或展成机构的精度,机械结构复杂,柔性差,同一个齿轮需要多台仪器测量。对于齿廓误差测量而言,展成式测量技术仅限于渐开线齿廓误差测量上。对于非渐开线齿轮的端面齿廓测量,采用展成法测量是十分困难得,因为展成机构太复杂并且缺乏通用性。

多年来,国内外诸多学者在大型齿轮测量领域进行了广泛的研究,丰富了大型齿轮测量方面的理论和方法。在检测仪器方面,各国均开发了由计算机控制的齿轮量仪,其机构大量应用新技术和新元件,如计算机数控技术运用于控制、驱动、数据处理等;光栅、同步感应器、容栅、磁栅、电感测微技术、电容测微技术、激光测量技术等用于位移测量,不断提高齿轮测量精度。总的发展趋势为:1)测量软件功能的增强和扩展,由于大齿轮的结构复杂大、重量重等原因,这就要促使其必须实现自动化的要求,即机电一体化的趋势。用计算机进行控制,用软件进行复杂的数据处理,也就大大提高了效率。2)

实现自动控制系统,由于很多机械加工场地存在一定的危险性,为了达到安全生产的目的,实现远程控制是大势所趋的事情。在远程控制室工作进行实时监控在机测量的同时还可以整理数据报告,检验和打印报告单,既节约时间又节约人力资源。对于测量数据的处理与利用,在早期的齿轮测量中。人工读指示表(如千分表等)获取齿轮误差,得到的是误差幅值,仅仅能用来评判被检项目合格与否。电动记录器的出现,靠人工读曲线,使工艺误差分析成为可能。而计算机的采用,使自动处理测量结果、分析工艺误差并将分析结果反馈到加工系统进而修正加工参数成为现实[9]。目前,在齿轮测量数据处理方面,通常采用的方法为最小区域法和最d'--乘法。理论上讨论最多的是最小区域法,实际中广泛使用的是最小二乘法,同时数字滤波技术也得到一定应用。如今的常用渐开线圆柱齿轮测量仪器有几十种。它们的测量方法都已经为人们所熟知。按照齿轮测量的原理不同,可以大致把它们分为两大类。~类是比较法测量,或者称为相对测量法测量。例如。齿形测量仪通过用机械范成或电子范成的渐开线与被测齿轮的实际曲线比较并获得误差。这种测量方法现在用途极为广泛。另一类是绝对测量法。例如,测量齿形时,把实际的齿形曲线与数学理论曲线相比较并获得误差。

2齿轮精度设计概述口]

渐开线圆柱齿轮精度设计涉及面广,现简述如下。

(1)公差组与精度等级

对齿轮传动一般有四个方向的要求

①传动准确,即传动比变化尽量小;

②传动平稳,即振动与噪声尽可能小.避免产生动

载荷与撞击;

③工作点面接触好,即载荷分布要均匀,避免动载荷

大时齿面应力集中,引起早期点蚀、折断而降低使用寿命;

④齿轮副侧隙要合适。

按上述分析,齿轮精度标准按误第特性对传动性能的

主要影响划分为三个公差组.

关丁齿厚极限偏差和公法线平均长度偏差两个项H,由于它们属于侧隙配台系统,所以不包括在上述三个公差组内。齿轮精度设计就是要确定两个公差组的精度等级,同时还要根据实际情况确定三个公差组内帽膻评定指标。

圆柱齿轮加工误差分析

何淑菊,邱淑英

(哈尔滨工程大学机电工程学院,黑龙江哈尔滨150001)从加工误差来看,影响齿向方向接触精度的主要因素是齿向误差,影响齿距累积误差的主要因素是齿轮的几何偏心,就齿轮坯基准面误差对齿向误差及齿距累积误差所产生的影响进行分析,并找出齿轮坯基准面跳动值的一种确定方法,并对加工齿轮改进方法进

行探讨。

1齿轮坯的基准面误差对齿向误差的影响

准面是指加工齿轮时的定位面,齿轮坯基准端面对齿轮轴心线的垂直误差,会使被

加工齿轮产生齿向误差或轴向齿距误差同理,当安装齿轮坯的夹具之端面(基准面)出现跳动时也会出现类似上述结果齿向误差不仅取决于上述两个方面,也受其他诸多因素的影响:

(1)齿轮安装误差;齿轮端面不平(端面跳动);夹具定位面不平(支承端面跳动)(2)机床刀架几何误差:横向倾斜,纵向倾斜

2基准面误差对齿距累积误差的影响

齿轮的齿距累积误差是分度圆上任意两个同侧齿面的实际弧长与公称弧长之差最大值的绝对值,而影响齿

距累计误差的主要因素是齿轮的几何偏心。,齿距累积误差是齿轮的几何偏心的 2倍.在实际加工中,引起工件偏心的齿轮几何偏心的原因有:

1)由夹具心轴的径向跳动所引起的齿轮几何偏心e1

2)由齿坯基准孔与夹具轴间的装配间隙引起的齿轮几何偏心e2 3)由夹具支承端面与心轴轴线不垂直即夹具支承面跳动造成的齿轮几何偏心e3

4)由齿坯端面跳动引起的齿轮几何偏心e4

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