两道关于公差简单的题，大家可以测试一下

佳速精机 · 发表于 2015-10-6 16:23:14

前来围观，学习

aysuio · 发表于 2015-10-6 22:50:05

ValleyViews 发表于 2015-10-6 03:56 % d }1 A9 ?. f8 B2 A( V9 B. B
关于第一题，目前我个人的看法仍然是0.2。尺寸公差只是控制该材料的厚度，而直线度是控制它箭头所指的平面的 ...

大侠可能对直线度平面度的适用范围有点混淆，
直线度是二维的，平面度是三维的。直线度的公差带是没有方向的，控制的是所标平面视角的所有线元素。
具体的，可以看看ASME Y14.5 所有问题迎刃而解
小子真是有些解释不动啦。不是敷衍大侠，小子最近实在心情不太好。呜呜。

ValleyViews · 发表于 2015-10-7 02:44:48

aysuio 发表于 2015-10-6 22:50
% h* w5 \, B: o1 d: S. \大侠可能对直线度平面度的适用范围有点混淆，- i S" f& C( m7 ^
直线度是二维的，平面度是三维的。直线度的公差带是没有方 ...

直线度是可以在某些平面上指定的。既然在平面上可以指定，就是可以应用在平面上的。ASME Y14.5 中的图 Fig. 5-6 Specifying Straightness of a Flat Surface 恰巧指的就是本题案例相同的情况。而您13楼给出的图示，也是在指定的平面上的。

aysuio · 发表于 2015-10-7 04:58:26

本帖最后由 aysuio 于 2015-10-7 05:08 编辑

ValleyViews 发表于 2015-10-7 02:44 0 g8 f3 {& A) ]6 ?( }7 }
直线度是可以在某些平面上指定的。既然在平面上可以指定，就是可以应用在平面上的。ASME Y14.5 中的图 Fi ...

:）
大侠，别用您啦，小子真担待不起，我是小弟：D
大侠这么认真，小子自然很愿意来跟大侠说一下。

In Y14.5
Application:
1. Straightness tolerance specifies a tolerance zone within which the EACH (This word is not in the standard, but the following explanations indicate the "EACH" information) considered element in the surface or derived median line must lie.
2. Straightness tolerance is applied in the view where the elements to be controlled are represented by a straight line.

These 2 sentences give us 3 information:
1. straightness tolerance controls each line elements of a surface when it is applied to the surface, or the derived median line when it is applied to the feature of size.
2. Straightness tolerance is ONLY applied in ONE VIEW where it refers to.
3. Straightness tolerances is applied to a nominal straight line. If the line is a curve, please use profile tolerance.

For this problem, straightness tolerance is applied to the surface, and in 2 VIEWS.
So it means 2 straightness tolerance control the straightness of each line elements of the surface in 2 VIEWS.
Line element is a 2D element, like it just has dimensions in X and Y, and NEVER think about you can measure line elements in Z axis. What you do is just to measure the line one by one according to the actual local sizes of the component (Means the straightness tolerance zone totally depends on the actual local sizes of your produced part)
When you talk about the flatness tolerance. This is a 3D element. I.E. it has dimesions in X,Y,Z. So when you check the tolerance, you check the whole surface at the SAME TIME where the flatness tolerance refers to.

This is why the straightness tolerance in that figure which I posted before can be 0, but the flatness tolerance can reach 0.6
If you still have any problem about this, please read the standard again from the first sentence of form tolerance section, then I think you will understand about this problem clearly and thoroughly.

If you are willing to talk with me about the problem, feel free to contact me

I'm here with you.

aysuio · 发表于 2015-10-7 05:02:43

Hi, Valleyviews,

You were saying the fig in Y14.5-2009. And yes, it is talking about this problem. I was confused by this section before, but this question just helped me to get over it! I hope that this question also let you clear some confusing theories up. Have a good day!

94371734 · 发表于 2015-10-7 12:15:14

请解释下为什么不是0.05。
机械设计手册给直线度的定义是：在给定方向上公差带是距离为公差值t的两平行平面之间的区域（第三章5-271）。
该面既要0.05又要0.2，那理所当然的可以认为平面度最大值为0.05。

类似于茴字有四种写法，实际应用中并没有多大的意义。

补充内容 (2015-10-8 10:07):
最近智商余额不足，给定方向上这几个字被我无视了。

aysuio · 发表于 2015-10-7 19:57:47

大侠，我自以为解释得很清楚了。。。再让我解释，说不过去啦吧- -！

bukeking · 发表于 2015-10-7 20:26:13

0.2,平面度可以限定直线度,反过来直线度也可以影响平面。4.7,只需考虑孔的尺寸和位置公差,c如果有平面度需要考虑,但是0位置度变的无意义。

bukeking · 发表于 2015-10-8 00:19:08

bukeking 发表于 2015-10-7 20:26
1 h$ Y6 s, f" i0.2,平面度可以限定直线度,反过来直线度也可以影响平面。4.7,只需考虑孔的尺寸和位置公差,c如果有平面度需要 ...

你好，如果直线度不能控制平面的话，这张图的意义何在，两向可以控制，一向足以影响，我认为没有问题。此处大部分人都可能直接标平面度，设计者应该是在完全符合性能要求的前提下，考虑到批量件或是工件长宽相差太多，结合机床的精度，让加工者选择合适的走刀方向进给量速度等参数，以最经济方式做出。

傻瓜丶 · 发表于 2015-10-8 00:58:02

看了第一题，觉得也是0.6，第二题就不懂了

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两道关于公差简单的题，大家可以测试一下

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