戴克伊GD&T基础资料课件.ppt

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1、Fundamentals of GD&T基础几何尺寸与公差概述 Based on ASME Y14.5M-2009Edited by:Mike Long编译：龙东飞ASME Y14.5M-2009 CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级GOAL 目标Understand what an engineering drawing is.懂得什么是工程图纸Understand why geometric tolerancing is superior to coordinate tolerance.懂得为什么几何公差优于坐标共差Unders

2、tand the modifiers and symbols used in geometric tolerancing.懂得几何公差修饰符和符号Remember:Tolerances should be as large as possible to keep manufacturing cost low.记住:为了降低制造成本，公差应该越大越好。CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级ENGINEERING DRAWINGS 工程图纸The Need for Precise Communications 精确交流的需要Enginee

3、ring drawings are a communications tools.Engineering drawings affect many parts of an organization.They have major impact on costs.工程图纸是精确交流的工具，对机构许多部门和成本构成重大影响。Consequences of Poor Drawings 品质差图纸后果(Cost in four ways:Money,Time,Material,Unhappy customers)（4 种成本：钱、时间、材料、不满意的客户）Cost of a Drawing Error

4、 图纸错误的成本When discovered by the Design Dept.设计 Model shop 样件 Production Group 生产 Customer 客户$1-10$100-500$2,000-100,000$50,000-$1,000,000Figure 1-1CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级Interpreting Dimensional Limits 解读尺寸极限 All dimensional limits are absolute.A dimension is considered to b

5、e followed by zeros after the last specified digit.所有极限尺寸都是绝对精确值，其最后一个数字后面都是零。26.02 means 26.020026 means 26.0016.54 means 16.540016.5 means 16.500For this dimension 26.0-26.2A part measuring26.201would be rejectedAnd 25.999 would be rejectedGD&T in the United States GD&T在美国ASME(American Society of

6、Mechanical Engineers)Y14.5(the standard number)M(Metric)-2009(the year the standard was approved)is a revision of ASME Y14.5M-1994 ASME（美国机械工程师协会）Y14.5（标准编号）M（公制）-2009（标准批准年份）是ASME Y14.5M-1994标准的升级版The ISO and ASME Y14.5M dimensioning standards are currently 80-90%common.ISO标准和ASME Y14.5M标准目前有80-90%

7、相同。CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级ASME and ISO Dimensioning Standard Comparison ASME和ISO标准比较ISOASME Y14.5Approach to dimensioning 编写方式Theoretical definition 理论性强Function of product功能性强Level of explanation 解释方式Few words/many figures文字少/图表多Thorough explanation解释透彻Cost of standards 标准

8、售价Over$1000Less than$200Number of standards 标准数目10-151CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级FUNDAMENTAL DIMENSIONING RULES(Rule#6)(ASME Y14.5M-1994)基本尺寸规则（6号规则）(ASME Y14.5M-1994)1.Each dimension shall have a tolerance,except those dimension

9、s specifically identified as reference,maximum,minimum,or stock(commercial stock)size.每个尺寸都应该有一个公差，但是，参考、最大/最小或型钢尺寸除外。2.Dimensioning and tolerancing shall be complete so there is full definition of each part feature.尺寸和公差应完整，才能完全定义零件形体。3.Dimensions shall be selected and arranged to suit the function

10、 and mating relationship of a part and shall not be subject to more than one interpretation.尺寸选择和布置，要适合零件功能和装配关系，而且只能有一种解释。4.The drawing should define a part without specifying manufacturing methods.图纸只定义零件，不要注明生产工艺。5.A 900 angle applies where centerlines and lines depicting features are shown on a

11、drawing at right angles,and no dimension is shown.900角在图纸上不标出。CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级THE COORDINATE TOLERANCILNG SYSTEM 坐标公差Definition 定义 Coordinate tolerancing is a dimensioning system where a part feature is located(or defined)by means of rectangular dimensions with given

12、 tolerances.用直角坐标系尺寸和公差定义零件位置或用尺寸和公差定义形体。SHORTCOMINGS OF COORDINATE TOLERANCING 坐标公差缺点Square Tolerance Zones 方形公差带(Figure 1-2)Fixed-Size Tolerance Zones 固定尺寸公差带(Figure1-2)Figure 1-2 Cylindrical vs.Square tolerance zone 圆柱对比方形公差带Square tolerance zone that results from coordinate tolerances坐标公差方形公差带Cy

13、lindrical tolerance zone that results from geometric tolerancing 几何公差圆柱形公差带(57%additional tolerance 增加公差带57%)CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级Appropriate uses for coordinate tolerancing 正确使用坐标公差-Plus/minus tolerancing is basically a caliper or micrometer type measurement.It works ver

14、y well for individual feature of size(Rule#1 Taylor Principle)but does not control the relationship between individual feature very well.This does not mean that limit tolerancing cannot be used.It is just important that we realize its limitations and problems.坐标（正负）公差基本上就是卡尺或千分尺类型测量，它可很好的测量单个形体尺寸（规则

15、#1）但不能控制两个形体之间的关系。这并不意味着坐标公差不能用，但我们要知道它的局限性和问题。Coordinate Dimension Usage 坐标公差使用Type of Dimension 尺寸类型Appropriate Use 好Poor Use 不好Size 尺寸XChamfer 倒角XRadius 半径XLocating Part Features 位置XControlling Angular Relationships 角度XDefining the Form of Part Features 形状XCH1 Introduction to the GD&T Hierarchy 介

16、绍GD&T组成层级 CONPARISON BETWEEN GD&T AND COORDINATE TOLERANCING 几何与坐标公差比较Drawing ConceptCoordinate Tolerancing 坐标公差 Geometric Tolerancing 几何公差Tolerance Zone Shape公差带形状孔公差带是方形或长方形-孔公差带较小-制造成本更高公差带是圆形，可使用直径符号-增加公差带57%-制造成本更低Tolerance Zone Flexibility公差带灵活性公差带尺寸固定-好零件被废弃-生产成本更高使用MMC修饰符使公差带在一定条件下增加-好零件被使用-

17、生产成本更低Ease of Inspection方便检测检测可以得到不同的检测结果-好零件被废弃-坏零件被接受基准系统可以统一检测设置-清楚指导检测-消除是否接受零件的争议CH2 Features,Rules and Concepts of GD&T 形体、规则和概念GOAL 目标Understand key terms and how they affect the interpretation of a drawing.懂得影响解读图纸的关键术语Understand Rule#1 and Rule#2.懂得规则#1和规则#2Understand the concepts of basic

18、dimensions,virtual condition,inner and outer boundary and bonus tolerance.懂得：基本尺寸、实效状况、内部边界、外部边界、奖励公差。FEATURES 形体Definition 定义 A feature is a general term applied to a physical portion of a part,such as a surface,hole,or slot.(Figure 2-1)形体就是一个零件上的一部分，如：表面、孔或槽。(A feature is any surface on a part.形体就

19、是零件的任何一个表面。）Figure 2-1 Examples of Features (This part has seven features 这个零件有7个形体)Left sideHole surfaceRight sideFrontTopBackBottomCH2 Features,Rules and Concepts of GD&T 形体、规则和概念Features of Size 尺寸形体 -A feature of size(FOS)is one cylindrical or spherical surfaces,or a set of two opposed elements

20、or opposed parallel surfaces associated with a size dimension,such as,the diameter of hole,or shaft.一个尺寸形体是一个圆柱面、球面、或一组两个相对的平行的元素或表面，且由一个尺寸连接。如：孔径或轴径。-Contains opposing elements or surfaces.包含相对元素或表面。-Can be used to establish an axis,median plane,or centerpoint.能被用来建立轴心线、中心面或中心点。-Is associated with

21、a size dimension.用一个尺寸连接。-Every feature of size contains one or more features surface(s)within it.A cylindrical FOS contains one feature:the cylindrical surface.A planar FOS is a FOS that contains two feature:the two parallel plane surfaces.每个尺寸形体包含一个或两个形体（表面）。一个圆柱尺寸形体包括一个表面。一个平面尺寸形体包括两个形体：两个平行平面表面。

22、-Usually(99%of the time),the opposing elements will both be the same type,for example,two opposing surfaces or two opposing line elements.通常（99%情况下），两个相对的元素是相同类型的，如两个表面或两条线。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念CH2 Features,Rules and Concepts of GD&T 形体、规则和概念Figure 2-2 Examples of feature

23、of size and non-feature of size(This part has four feature of size dimensions and three non-feature of size dimensions)（这个零件有4个尺寸形体尺寸和3个非尺寸形体尺寸）R514.2-4.82.0-2.6EG36-3824-2545036-37Internal and External Features of size 内部和外部尺寸形体In Figure 2-2,the 4.2-4.8 is internal 是内部 FOS;36-38,24-25 and 36-37 are

24、 external 是外部 FOS.CH2 Features,Rules and Concepts of GD&T 形体、规则和概念MATERIAL CONDITIONS 材料状况Maximum Material Condition(MMC)最大实体状况 The condition in which a feature of size contains the most amount of material everywhere within the stated limits of size.For example,the largest shaft diameter,the smalles

25、t hole diameter.尺寸形体包含有最多的材料，但仍然在尺寸范围内。如：最大的轴径，最小的孔径。Least Material Condition(LMC)最小实体状况 The condition in which a feature of size contains the least amount of material everywhere within the stated limits of size.For example,the smallest shaft diameter,the largest hole diameter.尺寸形体包含有最少的材料，但仍然在尺寸范围内

26、。如：最小的轴径，最大的孔径。(The MMC and LMC concepts can only be used when referring to a FOS)（MMC和LMC 概念只能应用于尺寸形体）Regardless of Feature Size(RFS)(ANSI Y14.5M-1982)不管形体尺寸 A term that indicates a geometric tolerance applies at any increment of size of the feature within its size tolerance,in-other-word,a geometr

27、ic tolerance applies at whatever size the part feature is produced.几何公差应用于尺寸形体在尺寸范围内任何尺寸。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念RULES 规则Rule#1 规则#1(Individual Feature of Size Rule 单个尺寸形体规则)-Often referred as the“envelope principle”or“perfect form at MMC”Rule#1 states where only a tolerance

28、of size is specified,the limits of size also control the limits of form.经常被称为“包容原则”或“MMC理想形状”。规则#1规定一个尺寸公差控制尺寸极限，还控制形状极限。(Rule#1 is a dimensioning rule used to ensure that features of size will assemble with one another.规则#1保证尺寸形体能相互装配。)-For features of size,where only a tolerance of size is specifi

29、ed,the surfaces shall not extend beyond a boundary(envelope)of perfect form at MMC.尺寸形体公差指定后，形体表面将不能突出MMC理想形状边界。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念How to Override Rule#1(Figure 2-3)怎样能否掉规则#1-Rule#1 applies whenever a feature of size is specified on a drawing.There are two ways Rule#1 ca

30、n be overridden.规则#1应用于任何尺寸形体，但有两种方法可否掉规则#1：-A straightness control applied to a FOS.直线度应用在尺寸形体。-A special note applied to a FOS.一个说明应用在尺寸形体。Rule#1 Limitation 规则#1 局限性 -Does not control the location,orientation,or relationship between features of size(i.e.angle E,G).(Figure 2-2)规则#1 不能控制位置度、方向度或尺寸形体

31、之间的关系。Rule#1 Exceptions 规则#1 例外 -A FOS on a non-rigid part 非刚性尺寸形体 -Stock sizes,such as bar stock,sheets,tubing or structural shapes etc.型钢尺寸，如：棒料、薄板、管材、结构钢材等。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念Figure 2-3 Feature control frame（FCF）placement 形体控制框放置 0.02 12.2-12.712.2-12.7 0.02A:形体控制框（FC

32、F）应用在形体 B:形体控制框（FCF）应用在尺寸形体OB=12.7Rule#1 applies.规则#1应用 OB=12.72Rule#1 overridden.规则#1失效CH2 Features,Rules and Concepts of GD&T 形体、规则和概念Rule#2 规则#2 RFS applies,with respect to the individual tolerance,datum reference,or both,where no modifying symbol is specified.MMC or LMC must be specified on the

33、drawing where required.(RFS-from Y14.5M-1982)不管形体尺寸（RFS）应用在单个公差、基准系或同时在两者，RFS不出现。MMC和LMC就必须在应用处出现。INTRODUCTION TO BASIC DIMENSIONS 介绍基本公差Basic Dimension 基本尺寸 -A basic dimension is a numerical value which have two uses on the engineering drawing.One is to define the theoretically exact location,size,

34、orientation,or true pro a part feature,Basic dimension is the goal,and a geometric tolerance specifies the amount of acceptable variation from the goal;the other is to define gage information(example:datum target):基本尺寸在图纸上有两个基本用途：一是定义理论精确位置、尺寸、方向或真实轮廓；基本尺寸是目标，必须伴有几何公差表示允许偏离目标的范围。二是定义测量基准目标。CH2 Featu

35、res,Rules and Concepts of GD&T 形体、规则和概念-Titleblock tolerance do not apply to basic dimension.Basic dimensions must get their tolerances from a geometric tolerance or from a special note.标题栏公差不能应用在基本尺寸。基本尺寸必须从别处得到它自己的公差。-Basic Dimension are theoretically exact,but gage-makers tolerances do apply.Gage

36、s should have no tolerances,but in industry gages do have tolerances.A rule of thumb is that gage tolerances are 10%of the part tolerances.基本尺寸是精确值，理论上没有公差，但实际操作上可用检具公差。检具理论上应该没有公差，但实际操作上要用检具公差，原则上，检具公差可用零件公差的10%来处理。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念INTRODUCTION TO:VIRTUAL CONDITION&BO

37、UNDARY CONDITIONS介绍实效状况和边界状况Definitions 定义-Virtual Condition(VC)is a extreme-case boundary generated by the collective effects of a feature of size with geometric tolerance at MMC or at LMC.The VC of a FOS includes effects of the size,orientation,and location for the FOS.The virtual condition bounda

38、ry is related to the datums that are referenced in the geometric tolerance used to determine the VC.实效状态VC是一个由尺寸形体在MMC或LMC和几何公差形成的极限边界。尺寸形体VC包括尺寸、位置和方向的影响，且与基准系关联。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念MMC Virtual Condition 实效状况(When in tol portion of feature control frame)VC=OB=MMC+Geometr

39、ic Tol 几何公差(External 外部 FOS)VC=IB=MMC Geometric Tol 几何公差(Internal 内部 FOS)LMC Virtual Condition 实效状况(When in tol portion of feature control frame)VC=IB=LMC Geometric Tol 几何公差(External 外部 FOS)VC=OB=LMC+Geometric Tol 几何公差(Internal 内部 FOS)RFS Inner and Outer Boundary 内部和外部边界OB=MMC+Geometric Tol 几何公差(Ext

40、ernal 外部 FOS)IB=MMC Geometric Tol 几何公差(Internal 内部 FOS)CH2 Features,Rules and Concepts of GD&T 形体、规则和概念INTRODUCTION TO BONUS TOLERANCE 介绍奖励公差Definition 定义-Bonus tolerance is only permissible when an MMC(or LMC)modifier is shown in the tolerance portion of a feature control frame.当MMC或LMC出现在FCF公差部分，奖

41、励公差才有可能产生。-Bonus tolerance comes from the FOS tolerance.奖励公差来自尺寸形体公差。-Bonus tolerance is the amount the actual mating size departs from MMC(LMC).当尺寸形体实际包容体尺寸从MMC或LMC离开，奖励公差才能等量产生。The MMC modifier is frequently used when the function of the FOS is assembly.When the function is assembly,the worst-case

42、 is when the FOS is at MMC with the full tolerance applied,or in other words,at its virtual condition.Since the fixed gage is made to the virtual condition,it represent the worst-case mating part.Therefore,if the part fits the gage,it will fit the mating part.The bonus concept works because the gage

43、 is fixed,and when the part departs from MMC,it can have more tolerance and still fit in the gage.尺寸形体装配常常使用MMC，而MMC实效状况就是最难装配的状况。由于固定检具就是用这个实效状况制成，能通过检具的零件就能保证与其它零件装配。由于检具固定，当零件尺寸从MMC离开时，就会产生奖励公差，仍然能通过检具。CH2 Features,Rules and Concepts of GD&T 形体、规则和概念Figure 2-4 Bonus tolerance examples 奖励公差案例0.70.

44、50.22.0 LMC0.60.40.22.10.50.30.22.20.40.20.22.30.30.10.22.40.20.00.22.5 MMCTotal Tolerance总公差Bonus tolerance奖励公差Flattness tolerance 平面度Feature AME2.0-2.5 0.22.7Note:Maximum bonus occurs when the AME is at LMC 最大奖励产生在AME在LMCGage opening检具开口0.2 bow at MMC弯曲0.2在MMCDrawingInterpretationCH3 Datums 基准GOAL

45、 目标Understand the datum system(planar datums)懂得基准系统（平面基准）Interpret datum targets.解读基准目标Interpret FOS datum specifications.解读尺寸形体基准（RFS or MMC）PLANNAR DATUMS 平面基准General Information on Datums 总体基准知识-Datums are theoretical reference planes,points,or axes and are simulated by the inspection equipment.基

46、准是理论上的基准平面、点或轴心线，它们由检测设备模拟。CH3 Datums 基准-A datum feature is a part feature that contacts a datum.Datum feature are part features and they exist on the part.基准形体是零件接触基准的那个形体，基准形体是在零件上。-A planar datum is the true geometric counterpart of a planar datum feature.一个平面基准是基准形体的真实几何模拟体-A datum feature simul

47、ator is the inspection equipment(or gage surfaces)used to establish a datum.(Of such quality that they are assumed to be perfect and are used as simulated datum).a simulated datum is considered a datum.一个基准形体模拟体是检测设备（表面），它们的质量好到被认为是完美的，用来建立基准，被认为就是基准。CH3 Datums 基准Datum Feature Symbol 基准形体符号 To speci

48、fy a planar datum,the datum identification symbol must be associated with a surface.基准形体符号要联到零件表面来指定一个平面基准。Datum Reference Frame(DRF)基准坐标系-A datum reference frame is a set of three mutually perpendicular datum planes.The datum reference frame provides direction as well as an origin for dimensional m

49、easurements.一个基准坐标系由三个相互垂直的平面组成，提供了方向和尺寸测量的起点。The 3-2-1 Rule 3-2-1规则-The 3-2-1 Rule defines the minimum points of contact with the primary datum as 3,the secondary datum as 2,and the tertiary datum as 1.零件与第一基准面最少三点接触，与第二基准面最少两点接触，与第三基准面最少一点接触。CH3 Datums 基准DATUM TARGETS 基准目标General Information on Da

50、tum Targets 总体基准目标知识-Datum targets are symbols that describe the shape,size and location of gage elements that are used to establish datum planes,axes,and points.Datum targets may also be used to establish a datum axis or centerplane.基准目标是描述检具形状、尺寸和位置的符号，它们被用来建立基准平面，基准线和基准点，也能被用来建立基准轴心线和中心面。Datum Ta