机械制造工艺机械制造工艺机电工程系 张莉Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.第三章 机械加工精度3.1加工精度与加工误差3.2工艺系统的几何误差3.3工艺系统变形引起的误差3.4加工误差的统计分析法及综合分析3.5提高加工精度的方法Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.重点 1. 影响加工精度的因素 2. 获得加工精度的方法及加工误差控制难点 1. 影响加工精度的因素 2. 加工误差的分析学习目的 了解各种因素对加工精度的影响规律，找出提 高加工精度的途径，以保证零件的加工质量。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.3. 2 工艺系统的几何误差一、加工原理误差加工原理误差是指由于采用了近似的加工方法、近似 的成形运动或近似的刀具轮廓而产生的误差。例如滚齿用的齿轮滚刀，就有两种误差，一是为了制 造方便，采用阿基米德蜗杆代替渐开线基本蜗杆而产生的 刀刃齿廓近似造形误差；二是由于滚刀切削刃数有限，切 削是不连续的，因而滚切出的齿轮齿形不是光滑的渐开线 ，而是折线，见图。成形车刀、成形铣刀也采用了近似的刀具轮廓。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.例如用模数铣刀铣齿轮，对于每种模数，可以只 用一套模数铣刀来分别加工在一定齿数范围内的 所有齿轮，见下表。用一把铣刀铣一组齿数的齿 轮，故存在加工原理误差。 Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.采用近似的成形运动和刀具刃形，不但可以简化机床或刀具的结构，而且能提高生产效率和加工的经济效益。只要能保证加工精度和零件的使用性能，一定的加工原理误差是允许的。这种误差不应超过相应公差的1015%。说 明Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.二、机床几何误差u 加工中刀具相对于工件的成形运动一般都是通过机床完成的，因此，工件的加工精度在很大程度上取决于机床的精度。u 机床制造误差对工件加工精度影响较大的有：主轴回转误差、导轨误差和传动链误差。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.机床几何误差的来源机床制造磨损安装机床几何误差的组成主轴回转误差导轨误差传动链误差Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.机床的几何误差组成机床几何误差机床传动链误差机床主轴回转误差机床导轨误差轴向窜动 径向跳动 角度摆动水平面内直线度 垂直面内直线度 前后导轨的平行度内联传动链始末两 端传动元件间相对 运动误差Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.1、机床主轴回转误差1）机床主轴回转误差的概念主轴的实际回转轴线对其理想回转轴线（一般用平均 回转轴线来代替）产生的偏移量。主轴回转误差的基本形式 轴向窜动 纯径向跳动 纯角度摆动Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.（1） 轴向窜动 轴向窜动是指瞬时回转轴线沿平均回转轴线方向的轴向 运动，如图所示，它主要影响工件的的端面形状和轴向尺寸 精度。 （2） 径向跳动 径向跳动是指瞬时回转轴线平行于平均回转轴线的径向 运动量。如图所示。它主要影响加工工件的圆度和圆柱度。 （3） 角度摆动 角度摆动是指瞬时回转轴线与平均回转轴线成一倾斜角 度作公转，如图所示，它对工件的形状精度影响很大，如车 外圆时，会产生锥度。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.实际上主轴回转误差是上述三种形式误差的合成。由 于主轴实际回转轴线在空间的位置是在不断变化的，由上 述三种运动所产生的位移（即误差）是一个瞬时值。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.主轴回转误差在实际中多表现为漂移。 漂移是指主轴回转轴线在每一转内的每一瞬时的变动 方位和变动量都是变化的一种现象。理想回转轴线实际回转轴线Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.轴承本身误差轴承间隙轴承间同轴度误差各段轴颈、轴孔的同轴度误差主轴系统的刚度和热变形等但它们对主轴回转精度的影响大小随加工方式而不同。2）影响主轴回转精度的主要因素Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.主轴采用滑动轴承（承载能力大，回转精度高，润滑 膜具有抗冲击作用 ）的车床类，主轴受力方向一定， 主轴颈圆度误差影响较大，轴承内径圆度误差没影响镗床主轴受力随镗刀旋转方向不断变化，轴 承孔误差影响大Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Clien