《公差原则》PPT课件.ppt

1、4.3 公差原则 Tolerance principles GB/T4249-1996,基本内容：Basic contents: 公差原则 1.Tolerance principles 有关术语及定义 2.Related terms and definitions 相关原则 3.Related principles 难点内容： Aporia contents: 相关原则的应用 The applications of related principles,一.公差原则 1. Tolerance principles 处理形位公差和尺寸公差之间关系的规定。 The regulations to s

2、olve the relationships between geometrical tolerances and dimensional tolerances,独立原则 公差原则 包容要求 相关原则 最大实体要求 最小实体要求,Tolerance principles,Independence principles,Envelope requirements,Maximum material requirements,Least material requirements,1.独立原则 Independence principles,定义：Definitions: 图样上给定的每一个尺寸公差

3、和形位公差要求，均是独立的，各自满足要求。Each size tolerance and geometrical tolerance requirements given on the drawings are both independent and satisfy the requirements 标注：Label: 不需加注任何符号 There is no need to add labeling any symbol,2.相关原则 Relative principles,定义图样上给定的形位公差与尺寸公差相互有关的公差要求。 DefinitionThe tolerance requir

4、ements that the given geometrical tolerances on drawings relate to size tolerances.,二. 有关术语及定义 Related terms and definitions,1 体外作用尺寸 External mating sizes,Dfe ：在被测要素的给定长度上，与实际内表面体外相接的最大理想面的直径或宽度。The maximum ideal surfaces diameter or width on the given length of measured elements and connects with

5、actual internal surface externally.,External,Internal,dfe：在被测要素的给定长度上，与实际外表面体外相接的最小理想面的直径或宽度。The minimum ideal surfaces diameter or width on the given length of measured elements and connects with actual external surface externally.,External,Internal,2 最大实体状态（尺寸）Maximum material condition (Size),最大实

6、体状态（MMC）：Maximum material condition(MMC) 实际要素在给定长度上,处处位于极限 尺寸之间，并具有实体最大时的状态.The state that actual elements are on the given lengthes.And each position is between the limit sizes thus containing the maximum material. 最大实体尺寸（MMS）：Maximum material size 实际要素在最大实体状态下的极限尺寸.The limit size that the actual e

7、lements are in the maximum material condition DM=Dmin dM=dmax 实体最大：占有材料量最多 Actual material is maximum:The possessed material volume is the most.,3 最小实体状态（尺寸）Least material condition(size),最小实体状态（LMC）：Least material condition(LMC) 实际要素在给定长度上,处处位于极限尺寸间，并具有实体最小时的状态. The state that actual elements are o

8、n the given lengthes.And each position is between the limit sizes thus containing the minimum material. 最小实体尺寸（LMS）：Least material size(LMS) 实际要素在最小实体状态下的极限尺寸. The limit size that the actual elements are in the minimum material condition DL=Dmax dL=dmin 实体最小：占有材料量最少 Actual material is minimum:The po

9、ssessed material volume is the least.,4 最大实体实效状态（尺寸）Maximum material virtual condition(Size),MMVC：给定长度上，实际要素处于最大实体状态，且该要素轴线、中心平面的形位误差等于给出公差值时的综合极限状态. MMVC:The comprehensive limit state when the geometrical deviations of this element axis and midplane equal to the given tolerance values and the actua

10、l elements are in maximum material conditions on given lengthes. MMVS：最大实体实效状态下的体外作用尺寸 MMVS:Exteral effect sizes in maximum material virtual condition. dMV = dmax+t DMV = Dmin-t,最大实体实效尺寸 Maximum material virtual size,最大实体实效尺寸 Maximum material virtual size,5 最小实体实效状态（尺寸） Least material virtual condit

11、ion(Size),LMVC： 给定长度上，实际要素处于最小实体状态，且该要素轴线、中心平面的形位误差等于给出公差值时的综合极限状态 The comprehensive limit condition that actual elements are in least material condition on given length and the geometrical errors of axis and central plane equal to the given tolerance values. LMVS： 最小实体实效状态下的体外作用尺寸 External mating s

12、izes under least material virtual condition dLV=dmin-t DLV=Dmax+t,L,L,4.形状公差（ t ）与尺寸公差（ T ）的关系：The relationships between geometrical tolerances and size tolerances,最大实体状态时：形状公差tmin=0 When in maximum material condition:Form tolerances tmin=0 最小实体状态时：形状公差 tmax=T When in least material condition:condit

13、ion:Form tolerances tmax=T,中心轴线 Central axis 垂直度 Verticality,小结：Summary:,尺寸公差Th Ts与形状公差 t Size tolerances Th Ts and form tolerances t 尺寸公差具有双重职能：控制尺寸公差和形状公差 Size tolerances contain dual functions:Controling size tolerances and form tolerances.,dmin Dmax,dmax Dmin,5.最大实体要求应用举例（一） Application examples

14、 of maximum material requirements(1),该轴应满足下列要求：This shaft should satisfy the following requirements: 实际尺寸：9.985 10 Actual size: 边界：实际轮廓不超出最大实体实效边界 Boundary:Actual cam doesnt overstepping maximum material virtual boundary. dMV=dM+t1=10+0.005 =10.005mm 即体外作用尺寸：External mating size dfe10.005,A, 10h7,A,

15、 0.005 M,合格条件：Acceptance condition: 轴：dfe dMV dmax+t1=10.005 Shaft 9.985 da 10,尺寸公差：Ts=0.015 Size tolerance: 形状公差：Form tolerance: When: 当：dM=dmax=10 t=t1=0.005 When: 当：dL=dmin=9.985 t=t1+t2=t1+Ts=0.005+0.015=0.02,直线度 Straightness,da,9.985, 10（dM）, 10.005(dMV),0.005,0.02,-0.3,动态公差图 Dynamic tolerance chart,1.尺寸公差Th Ts与形位公差t的关系：The relationships between size tolerances Th Ts and geometrical tolerances t. 当 Da = Dmin da = dmax ： 允许形位公差 t=tmin=t1 All