Interchangeable Measurement Techniques - Geometric Errors

1.Causes of geometric errors

（1）The machining process system is error-free（机床,刀具,卡具）

（2）Vibration during machining,受力变形,磨损

 2.The effect of geometric errors

（1）Affects the functional requirements of the part

The straightness and flatness of the surface of the machine tool guide rail affect the movement accuracy of the machine tool holder

（2）Affects the fit properties of parts

Clearance fit for cylindrical joints（Errors in the shape of the cylindrical surface will accelerate relative rotational wear,Reduced life and motion accuracy）

（3）Affects the free assembly of parts

3.The object of study of geometric tolerance

几何要素：Points, lines and faces that make up the geometric features of a part

4.Classification of geometric features

Classification according to structural characteristics：

组成要素：The point line surface of the part surface

导出要素：The center point obtained from one or more constituent elements,centerline or face

 5.Geometric tolerance features and bullets

 6.Geometric tolerance annotation method

 There is no benchmark

 There is a benchmark

 There are two benchmarks

 There are three benchmarks

There are public benchmarks

 There are multiple requirements

 Tolerance zone is cylindrical is plus diameter symbol,If it is a ball, add itS

 7.datum symbol

 Annotation on the part drawing

 The arrow points to the part surface or an extension of the part surface

 When the actual surface cannot be labeled,Extension cords can be drawn

 对于轴类零件,Arrows should be aligned with dimension lines

 Guide lines are aligned with dimension lines

 A small circle is added to the figure to represent the entire perimeter surface

 图中0.05/200Indicates that the length is only200The straightness of the straight line is 0.05,the rest of the pictures,Both limit the benchmark to the range of the thick blue dotted line

For example, a flat plate or ball that is not installed

 其余的L R等同理

 8.Tolerance type

8.1 直线度

 含义是：Extracted features must be at a spacing of 0.1mmthe area between the lines

 8.2 平面度

含义是：The plane must lie at distance 0.08mmbetween two parallel planes,If the flat surface is not allowed to have bulges,就加上NC

8.3圆度

 8.4圆柱度

9.方向公差

 注意：The shape tolerance must be less than the orientation tolerance

 9.1平行度

 9.2垂直度

 9.3倾斜度

 10.位置公差

 10.1 同心度

 10.2同轴度

 10.3对称度

 11.位置度

 11.1线轮廓度

 11.2面轮廓度

 12.Runout tolerance

 图中,The circular runout value is 0.1,Full beating is0.2