戴克伊GD&T基础资料.ppt

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1、FundamentalsofGD&T基础几何尺寸与公差概述BasedonASMEY14.5M-2009Editedby:MikeLong戴克伊公司参考资料编译：龙东飞ASMEY14.5M-2009CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级GOAL目标Understandwhatanengineeringdrawingis.懂得什么是工程图纸Understandwhygeometrictolerancingissuperiortocoordinatetolerance.懂得为什么几何公差优于坐

2、标共差Understandthemodifiersandsymbolsusedingeometrictolerancing.懂得几何公差修饰符和符号Remember:Tolerancesshouldbeaslargeaspossibletokeepmanufacturingcostlow.记住:为了降低制造成本，公差应该越大越好。CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级ENGINEERINGDRAWINGS工程图纸TheNeedforPreciseCommunications精确交流的需要

3、Engineeringdrawingsareacommunicationstools.Engineeringdrawingsaffectmanypartsofanorganization.Theyhavemajorimpactoncosts.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。ConsequencesofPoorDrawings品质差图纸后果(Costinfourways:Money,Time,Material,Unhappycustomers)（4种成本：钱、时间、材料、不满意的客户）CostofaDrawin

4、gError图纸错误的成本Whendiscoveredbythe…DesignDept.设计Modelshop样件ProductionGroup生产Customer客户$1-10$100-500$2,000-100,000$50,000-$1,000,000Figure1-1CH1–IntroductiontotheGD&THierarchy介绍GD&T组成层级TypesofTolerances公差的类型-Alimittolerance极限公差(12.0-12.5)-Aplus-minustolerance正负公差(12.250.25

5、equalbilateraltolerance)-Aunilateraltolerance单项公差(12+0.50)-Anunequalbilateraltolerance双向不等公差(12.2+0.3-0.2)(Wherelimitorbilateraltolerancingisused,eachtolerancevalueshouldhavethesamenumberofdecimalplaces,usingzeroswherenecessary.)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–In

6、troductiontotheGD&THierarchy介绍GD&T组成层级InterpretingDimensionalLimits解读尺寸极限Alldimensionallimitsareabsolute.Adimensionisconsideredtobefollowedbyzerosafterthelastspecifieddigit.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。26.02means26.020…0means26.0…016.54means16.540…016.5means16.50…0Forthisd

7、imension26.0-26.2Apartmeasuring26.201wouldberejectedAnd25.999wouldberejectedGD&TintheUnitedStatesGD&T在美国ASME(AmericanSocietyofMechanicalEngineers)Y14.5(thestandardnumber)M(Metric)-2009(theyearthestandardwasapproved)isarevisionofASMEY14.5M-1994ASME（美国机械工程师协会）Y14.5（标准编号）M（

8、公制）-2009（标准批准年份）是ASMEY14.5M-1994标准的升级版TheISOandASMEY14.5Mdimensioningstandardsarecurrently80-90%common.