[交通运输]GDampT 福特汽车形位公差培训资料.ppt

2. General Tolerancing and Principles 2) Material Conditions MMC 最大实体原则： 3） Datum 基准 The datum reference Frame (基准参考体系） The datum precedence and minimun contact with a part is　基准优先次序和与部件的最小接触为 Primary datum – three points　第一基准　３点 Secondary datum – two points　第二基准　２点 Tertiary datum – one point 第三基准　１点 Point as Primary Datum Plane as Primary Datum 1) Geometric Characteristic Symbols Flatness Circularity Cylindricity is a condition of a surface of revolution in which all points of the surface are equidistant from a common axis. 圆柱面是当表面上所有的点都与一公共轴线等距离的旋转表面的状态。 The profile tolerance (轮廓度) specifies a uniform boundary along the true profile within which the elements of the surface must lie. It may be applied to an entire surface or to individual profiles taken at various cross sections through the part. Orientation (定向) The tolerances control the orientation of the features to one-anther. 公差带形状与基准相关 4. Reference Documents Straightness is the condition where an element of a surface or an axis is a straight line Flatness is the condition of a surface having all elements in one plane Circularity is a condition of a surface of revolution as cylinder, cone and sphere. Cylindricity is a condition of a surface of revolution in which all points of the surface are equidistant from a common axis. Form tolerance（形状公差） control straightness, flatness, circularity and cylindricity. Straightness is the condition where an element of a flat surface or cylindrical surface is a straight line An axis or a center plane is a straight line. Straightness Specifying straightness of an Axis - RFS 轴线必须在0.04圆柱公差带内， 于尺寸公差无关 每个圆形单元必须在15.98~16.02 尺寸范围之内。 Specifying straightness of an Axis Per Unit 轴线必须在0.5圆柱公差带内 轴线在任何25mm长度内必须位于0.1mm 圆柱公差带内。 每个圆形单元必须在15.8~16.02 尺寸范围之内。 Flatness is the condition of a surface having all elements in one plane 面上所有的点必须位于两个平行平面之间。他们分开的量即为规定的平面度公差 RFS is implied. Specifying flatness of an surface 平面度公差必须小于尺寸公差 表面在间距0.25两平面之间 尺寸必须在45.0~46.0之