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类型戴克伊GD&T基础资料.pptx

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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-2009 Edited by: Mike Long戴克伊公司参考资料 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

    2、几何公差优于坐标共差Understand 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 Communica

    3、tions 精确交流的需要Engineering 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

    4、客户),Figure 1-1,CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级,Types of Tolerances 公差的类型- A limit tolerance 极限公差 (12.0-12.5)- A plus-minus tolerance 正负公差 (12.250.25 equal bilateral tolerance)- A unilateral tolerance 单项公差 (12+0.50)- An unequal bilateral tolerance 双向不等公差 (12.2+0.3-0.2 ) (Where limit

    5、 or bilateral tolerancing is used, each tolerance value should have the same number of decimal places, using zeros where necessary. )当使用极限或双向公差时,每个公差值小数点后应该有同样多位数,必要时用零),CH1 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 dim

    6、ension is considered to be 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。,GD&T in the United States GD&T在美国ASME (American Society of Mechanical Engineers) Y14.5 (the standard number) M (Metric) -2009 (the year the standard was approved) is a revision of ASME Y14.5M-199

    7、4 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%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,CH1 Int

    8、roduction 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)Each dimension shall have a tolerance, except those dimensions specifically identified as reference, maximum, minimum

    9、, 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。Dimensions shall be selected and arranged to suit the function and mating relationship of a part and shall not be

    10、 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。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。A 900 angle applies where centerlines and lines depicting features are shown on a drawing at right angles, and no dimension is shown. 90

    11、0角在图纸上不标出。,CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级,Implied basic 900 angles - A 900 basic angle applies where centerlines of features in a pattern (or surfaces shown at right angles on a drawing ) are located and defined by basic dimensions and no angle is specified. 基本900角在图纸上不标出。Implied

    12、basic zero dimension Where a centerline or centerplane of a FOS is shown in line with a datum axis or centerplane, the distance between the centerlines or centerplanes is an implied basic zero. 基本0尺寸在图纸上不标出。Unless otherwise specified, all dimensions are applicable at 200 C.零件常温200 CAll dimensions an

    13、d tolerances apply in the free-state condition. 零件自由状态。Unless otherwise specified, all geometric tolerances apply to the full depth, length, and width of the feature. 除非另有说明,几何公差应用全部形体长、宽、高。Dimensions and tolerances apply only at the drawing level where they are specified. A dimension specified on a

    14、 detail drawing is not mandatory for that feature on the assembly drawing. 尺寸公差应用于它标明的层级,装配图尺寸公差不能强制该层级尺寸公差。,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 defi

    15、ned) by means of rectangular dimensions with given 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,CH1 Introduction

    16、 to the GD&T Hierarchy介绍GD&T组成层级,Ambiguous instructions for Inspection 检测指导不明确 (Figure 1-3)Should the hole location be measured as shown in setup A or B 应该用A或B方法测孔的位置A BFigure 1-3 Method of Inspection 检测方法,CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级,Appropriate uses for coordinate tolerancing

    17、正确使用坐标公差- Plus/minus tolerancing is basically a caliper or micrometer type measurement. It works very 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. I

    18、t 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#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。,CH1 Introduction to the GD&T Hierarchy介绍GD&T组成层级,THE GEOMETRIC DIMENSIONING AND TOLERANCEING SYSTEM 几何尺寸和公差系统Definition and Philosophy 定义和哲学GD&T i

    19、s an international language that is used on engineering drawings to accurately describe a part. Geometric tolerancing encourages a dimensioning philosophy called “functional dimensioning.” which is a dimensioning philosophy that defines a part based on how it functions in the final product.GD&T是一个在工

    20、程图纸上精确描述零件的国际语言。几何公差鼓励一个“功能尺寸”的哲学,就是以零件的功能来确定如何定义零件。GD&T BENEFITS 优点 Improves Communication 改善交流 Provides Better Product Design 提供更好的产品设计 Increases Production Tolerances 增加生产公差,CH1 Introduction to the GD&T Hierarchy 介绍GD&T组成层级,CONPARISON BETWEEN GD&T AND COORDINATE TOLERANCING 几何与坐标公差比较,CH2 Features

    21、, 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 dimensions, virtual condition, inner and outer boundary and bonus tolerance. 懂得:基本尺寸、实效状况、内部边

    22、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)

    23、,CH2 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 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

    24、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 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 F

    25、OS 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。- Usually (99% of the time), the opposing elements will both be the same type, for example, two opposing surf

    26、aces 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 of size and non-feature of size ( This part has four feature of size dimensions and three non-fea

    27、ture 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),Internal 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 external 是外部 FOS.,CH2 Features, Rules and Concepts of GD&T 形体、规则和概念,Actual Local Size (ALS) 实际局部尺寸Actual local size is the val

    28、ue of any individual distance at any cross section of a FOS. A two-point measurement is often considered an actual local size.一个实际局部尺寸是尺寸形体任何一个截面间的距离。两点测量通常被认为是一个实际局部尺寸。Actual Mating Envelope (AME) 实际包容体For an external feature of size; a similar perfect feature counterpart of the smallest size which

    29、 surrounds the feature so it contacts the high points of the surface(s). For an internal feature of size; a similar perfect feature counterpart of the largest size which fits inside the feature so it contacts the high points of the surface(s) 对外部尺寸形体:就是一个最小尺寸包在该形体上的一个与其相似的完美形体。对内部尺寸形体:就是一个最大尺寸膨胀在该形体

    30、上的一个与其相似的完美形体。(Actual mating envelope is a variable value, derived from an actual part)(实际包容体是一个由实际零件得来的变值),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 e

    31、verywhere within the stated limits of size. For example, the largest shaft diameter, the smallest 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 limit

    32、s 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。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 t

    33、olerance applies at any increment of size of the feature within its size tolerance, in-other-word, a geometric 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 Ru

    34、le 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 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 featu

    35、res 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 specified, 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,- When t

    36、he actual local size of a FOS has departed from MMC toward LMC, the form is allowed to vary by the same amount. 当尺寸形体实际局部尺寸从MMC向LMC变化,形体形状被允许相 同量变形。- The actual local size of an individual feature of size must be within the specified tolerance of size. 单个尺寸形体实际局部尺寸必须在规定的尺寸公差范围内。- There is no require

    37、ment for a boundary of perfect form at LMC. If a feature of size is produced at LMC, it can vary from true form by the amount allowed by the MMC boundary. 没有 LMC理想形状边界要求。,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 feat

    38、ure of size is specified on a drawing. There are two ways Rule #1 can 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 relationsh

    39、ip 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,Figur

    40、e 2-3 Feature control frame (FCF) placement 形体控制框放置,12.2-12.7,12.2-12.7,A: 形体控制框(FCF) 应用在形体,B: 形体控制框(FCF)应用在尺寸形体,OB = 12.7 Rule #1 applies. 规则#1应用,OB = 12.72 Rule #1 overridden. 规则#1失效,CH2 Features, Rules and Concepts of GD&T 形体、规则和概念,Inspecting a Feature of Size 检测尺寸形体- The MMC size and the Rule #1

    41、 envelope can be verified with a Go gage. A Go gage is a gage that is intended to fit into (for a internal FOS) or fit over (for an external FOS) the FOS. A Go gage is made to the MMC limit of the FOS and has perfect form. To fully verify the Rule #1 effects, a Go gage must be at least as long as th

    42、e FOS it is verifying. 通规可测量尺寸形体MMC尺寸和规则#1 包容体。通规就是尺寸形体MMC理想形状形体,至少要与被测形体一样长,能完全通过为合格。- The minimum size (LMC) of a FOS can be measured with a No-Go gage. A No-Go gage is a gage that is not intended to fit into or over a FOS. A No-Go gage is made to the LMC limit of the FOS. A No-Go gage makes a two

    43、-point check; a caliper or snap could be used as a No-Go gage. Multiple two-point checks are required. 止规可测量尺寸形体LMC尺寸。止规就是尺寸形体LMC尺寸,要做许多位置两点检测,不能通过为合格。,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, wher

    44、e no modifying symbol is specified. MMC or LMC must be specified on the 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 th

    45、e engineering drawing. One is to define the theoretically exact location, size, orientation, or true profile of 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 t

    46、arget): 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 Features, 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。

    47、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.Gages 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

    48、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 & BOUNDARY 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

    49、LMC. The VC of a FOS includes effects of the size, orientation, and location for the FOS. The virtual condition boundary 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, Rule

    50、s and Concepts of GD&T 形体、规则和概念,- Inner Boundary (IB) is a extreme-case boundary generated by the smallest feature of size minus the stated geometric tolerance (and any additional tolerance, if applicable). (Usually IB is used on internal FOS)内部边界IB是最小的尺寸形体减去几何公差(和可能的额外公差)形成的最小极限边界。- Outer Boundary (OB) is a extreme-case boundary generated by the largest feature of size plus the stated geometric tolerance (and any additional tolerance, if applicable). (Usually OB is used on external FOS)外部边界OB是最大的尺寸形体加上几何公差(和可能的额外公差)形成的最大极限边界。,

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