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发表于 2013-2-4 00:14:06
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本帖最后由 datafield 于 2013-2-4 00:40 编辑
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我先占座,有空再来一点一点翻译。
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metaldork (Agricultural) | 8 Mar 12 12:53
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Can anyone please clarify if a perpendicularity call out is controlled by a basic dimension or not? In other words is the tolerance zone centered on a basic dimension? & `9 i1 z& ]% b5 a
哪位可以帮忙介绍一下,垂直度要求,是否须与理论尺寸相关联?或者说,垂直度的公差带,是否以理论尺寸为中心?, W9 W) M/ b: O7 H
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1 z2 k! J1 M8 p3 D9 yCheckerHater (Mechanical) | 8 Mar 12 13:03
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No, it is sufficient by itself.
! v: p% c* j" u# v$ _+ C, x不,垂直度本身已经够了。9 A+ E b) M5 `# {* B; w' |
9 G( B9 N4 K7 G! ^It MAY be used together with basic dimensions when used to refine the Position.3 M/ o, B. _% }
当然,在定义位置的情况下,也可以与理论尺寸联合使用。
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powerhound (Mechanical) | 8 Mar 12 13:42
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No, the tolerance zone moves with the feature being controlled. 不,公差带随着其控制的形体而移动。
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Powerhound, GDTP T-0419
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* e+ M+ l, l0 qmetaldork (Agricultural) | 8 Mar 12 13:56 / [1 @, p, o6 v
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The surface is dimensioned from a parallel surface ...would the perp callout control the dimension and if so should it be basic? 8 A1 v! _& N( P7 d
平面从互相平行的另一个面来定义尺寸……会要求用垂直度来控制尺寸吗?若是,尺寸要为理论尺寸吗? |
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! J8 O/ m& G' j8 ^CheckerHater (Mechanical) | 8 Mar 12 14:17
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There is a difference between Perpendicularity and Parallelism. 垂直度与平行度,是不一样的。
; E$ {! |1 n. u. WEven in case of Parallelism the dimension can be toleranced; the Parallelism will refine the tolerance. 就算是平行度,尺寸也可以标明公差;平行度将进一步限定公差。
1 F4 }8 Y& L% m4 R8 fIf I don't understand something, please provide a picture. 如果不太明白,请给图示意。9 X# j) b T$ g- V
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3 y5 {- y" R$ @+ B5 o/ pBelanger (Automotive) | 8 Mar 12 14:35 . u9 z" N/ a9 o# _4 F) x
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First, there is an implied basic dim with perpendicuarity. It is the 90 degree relationship to the datum. That's not the kind you were thinking of, but I feel obligated to mention it. 首先,垂直度有一个默认的基本前提,即:与基准的90度关系。这不是你所想的,但我有义务得先申明一下。! R% r9 D7 N7 V& K# b* ~
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You ask about locating the perp tolerance zone. That should never happen with basic dims. The perp tolerance zone can float freely within whatever other constraints there might be. 你问的是垂直度公差带的位置。这与理论尺寸无关。垂直度公差带的位置,可以在其它约束里自由移动,如果有约束的话。& F$ h' n- Z8 m3 `, x
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IOW, the per tolerance never controls the distance from the parallel surface. There should be something else to do that, such as plus/minus. The perp doesn't get added to that; it must operate within it. 哦,平行平面的距离,不受垂直度控制,而受控于其它因素,比如+/-。垂直度不会扩大它;垂直度必须在此范围内。( _/ ?" v) X( X% g& ?/ }
' \( r- k" m; t* @. VJohn-Paul Belanger3 c& f6 u3 P5 [: i Y1 Y; h
Certified Sr. GD&T Professional
2 f9 e* Q6 X! \1 JGeometric Learning Systems/ i9 v; G7 Q8 \, V3 [& T0 O( f
http://www.gdtseminars.com
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' ] i; d* `" f \/ V0 K+ sdgallup (Automotive) | 8 Mar 12 14:38
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The surface can be dimensioned from a parallel surface and still have a perpendicularity to a datum that is normal to both surfaces. The dimension will control location and to the extent that the envelope principal applies, form. The perpendicularity must be a refinement of the dimension tolerance, typically half or less. 某个面,可以从与其平行的另一个面来标注尺寸来定义距离,同时,可以标注垂直度(基准与此两面都垂直)。尺寸,按包容原则来控制位置。垂直度公差,必须小于尺寸公差,通常为尺寸公差的一半或更少。 ----------------------------------------
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
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axym (Industrial) | 8 Mar 12 15:09 4 }$ p. U I5 O, d
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metaldork,! T! s2 F! |) ?- p
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The way I like to look at it is that the Perpendicularity zone can always freely translate - its location is never controlled relative to anything. So the Perpendicularity zone is always completely independent of any linear dimensions (basic or directly toleranced) connected to the considered feature. 我认为,垂直度公差带,是可以自由移动的——它的位置,不受任何约束。故,垂直度公差带,总是与被测形体的线性尺寸(理论尺寸或直接标注公差的尺寸)相互独立的。
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In the scenario you described, the Perpendicularity doesn't have to be a refinement of anything. The directly toleranced dimension doesn't control the squareness, so the Perpendicularity tolerance doesn't need to refine it.Evan Janeshewski: G0 V! r" O M
9 e+ m o% x/ [3 M3 M7 ~. LAxymetrix Quality Engineering Inc.5 r) F9 l) h: E' I" {
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& u0 M3 f9 L9 H5 v- Z" u Ppmarc (Mechanical) | 8 Mar 12 15:13
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I am with J-P on this, the only basic dimension that applies for perpendicularity is basic 90 degrees to the datum and it is usually not shown on a print due to implied basic 90 deg dimension rule.
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4 N% A; i* [0 i9 v+ _+ q; ?dgallup,
' S5 d3 Y- u+ g D) n( jYou said: "The perpendicularity must be a refinement of the dimension tolerance, typically half or less."
9 S4 h. N+ f( a2 u) n% cI would be careful with that. If perpendicularity callout is applied only to one "side" of a dimension, its value can be whatever one can imagine (assuming there is no general angular tolerance shown on the print that would control a relationship of the other "side" of the dimension relative to the datum).
, O7 m- |7 Y4 U% K: |. Q( c7 UThe other story is when there are two perpendicularity callouts applied to both "sides" of the dimension. In that case, my vote is their values can be as big as the dimension tolerance (and not half of it).
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CheckerHater (Mechanical) | 8 Mar 12 15:57
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Evan,
6 {7 g/ Z. r0 G) QCould you please clarify: Do you believe that perpendicularity tolerance zone can "freely translate" OUTSIDE of linear dimension /position tolerance zone?2 [ |* H2 e$ M. V
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2 ~) O. @' E. S, H1 l& BBelanger (Automotive) | 8 Mar 12 16:39
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CH, picture a U-shaped bracket -- sort of like field-goal posts. Now take both vertical posts and bend them 20 degrees to the left. Are they within the size (width) tolerance? Yes. Is the post on the left within its perpendicularity tolerance to the ground? No.
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- D H2 G0 p5 d8 WSo there is no relationship between the tolerance number for the size across the posts and the tolerance number chosen for the perpendicularity.0 f8 `( s+ y& F. u" w5 o
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Sorry for jumping in, Evan. Feel free to modify my explanation John-Paul Belanger" r% l' J# }' o% r2 i- i( ]/ U
Certified Sr. GD&T Professional
* q5 G" j9 q& t5 A$ h( HGeometric Learning Systems
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# p/ ], k8 T u7 S! Uaxym (Industrial) | 8 Mar 12 17:54 7 X' ` o" D/ m
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Quote (checkerhater):"Could you please clarify: Do you believe that perpendicularity tolerance zone can "freely translate" OUTSIDE of linear dimension /position tolerance zone?" " \- B% ^2 L! ^" p8 q
( X5 ?1 `' a2 v, N3 P: [1 H+ m( HCH,
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1 c- N# q/ I+ IQuick answer, yes. But of course there's more to it.
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If we think purely in terms of the tolerance zone mechanics, which I always try to do, then the Perpendicularity zone is allowed to translate outside of the linear dimension / Position tolerance zone.9 Z2 ?& W$ W$ B! i9 ?. y. v
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It is true that the feature might not conform to the Position tolerance if the Perpendicularity zone had to translate partly outside of the Position zone. It definitely wouldn't conform if the Perpendicularity zone had to translate completely outside of the Position zone. But that is a different consideration./ x0 P4 [4 v9 D% f) t5 O
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The way I like to look at it is that the Position tolerance and the Perpendicularity tolerance are independent requirements, that can be evaluated independently of each other. This is the only way that I am able to make sense of it all. Some GD&T books state or imply that the orientation zone must float within the location zone, but to me this is an oversimplification. It is possible for part of the orientation zone to extend outside of the location zone, and still have the feature conform to both tolerances.Evan Janeshewski) _" {. ?( Q' Q, K6 p7 N. y
) p/ k( o5 Y2 OAxymetrix Quality Engineering Inc.7 v* @2 H* v2 z V) z0 g( q/ f
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CheckerHater (Mechanical) | 9 Mar 12 6:32
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Thank you Evan,
' o0 n* l( x U* fAppreciate straight "Yes" - rare thing nowadays.
! e- _" U( c- fUnfortunately I am not convinced. Imagine the hypothetical situation:4 {# t# l4 w- F" I
You are using some sort of measuring machine. You find out that the axis of certain hole (or boss) is laying WITHIN perpendicularity tolerance, but OUTSIDE of position tolerance.2 Y3 J: w; H0 N
Would you suggest the part to be accepted or rejected? (Another straight Yes or No will be appreciated) z& Z. u* k& ?* x/ a% ~! C
I personally believe that your position and perpendicularity zones should at least partially overlap. (It will create some interesting conditions that probably were never fully documented, but nevertheless).. T8 r6 f" U8 v( @9 B: }
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Joan-Paul,
& D' g. |' u, U% J8 C4 wYour argument appears to be far stretched and borderline cheating (Sorry)2 X) [, y) z7 R/ R; m" z) ^) [* {1 b
You said it yourself: "Is the post on the left within its perpendicularity tolerance to the ground? No." So what you describe is "bad" part that should never be accepted in the first place. The purpose of GD&T is to describe the parts we will accept, right?
7 i% \8 E. y! Q; G0 [) m" eAnother stretch: "tolerance number for the size across the posts". Most people would consider "fork" being two features of size, not one. Is space between two holes feature of size?
8 d' r4 Z- `4 e/ V; X. \ BSo your argument basically is: "If we can make bad part from ambiguous drawing, then there is no relationship between the tolerances". Sorry, but I am not buying it.3 } m5 H: K' M+ M5 x, Z" u
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9 Q; a Z$ \" q1 o, t( bBelanger (Automotive) | 9 Mar 12 7:03
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CH -- I don't quite understand your concern. First, yes, the space bewteen the posts is a feature of size; so is the outside of the posts. But my example was really meant to discuss surface perpendicularity (I just used the posts as a visual example. Sorry for the confusion.)
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"Is the post on the left within its perpendicularity tolerance to the ground? No."
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+ W, I7 n: D* x9 }The reason I wrote that is that many people think that a size dimension also controls orientation -- that's not true! So I'll rephrase it differently: Two vertical surfaces can lean in the same direction and still be within perpendicularity tolerance. They are also within the size tolerance. But there is no connection between the tolerance values for the perpendicularity and the size.John-Paul Belanger1 A5 V: `3 `/ C; P j9 k$ r
Certified Sr. GD&T Professional
: }5 n; V8 \! y/ N1 h8 d1 p4 N; ?Geometric Learning Systems
9 @! w* h) U# V! ?http://www.gdtseminars.com
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CheckerHater (Mechanical) | 9 Mar 12 7:54 & G& j- p: A9 S- ~' U
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0 j% t' W0 ~. J1 U% rThank you JP, we are getting somewhere.
6 K0 U2 O8 @+ Y- VLet say, we have FOS with perpendicularity requirement added. The size tolerance is .001, the perp. .100. But they both affect VIRTUAL CONDITION, right? Now, what if we add position requirement to our virtual condition?! P# L$ v z$ Y) D* @) F
You see, I never said perpendicularity is a refinement of size. But I still insist on the following conditions: Perp. tolerance zone being outside of position tolerance zone makes no sense. Perp. tolerance zone being larger than position tolerance zone makes no sense. It may be legal though.
r9 s9 M' t4 qWhen you have 2 FCFs applied to same feature, their requirements have to be met together (I didn't say "simultaneously"). If perp. tolerance is .100 and position is .010 position requirement controls perp. indirectly and makes perp. requirement useless.9 q; r' D" G0 U3 [2 |
So, when used together with position requirement, perpendicularity only makes sense when perp. tolerance zone is smaller than position tolerance zone, and both tolerance zones overlap at least partially. To me it means "refinement".
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pmarc (Mechanical) | 9 Mar 12 8:57 3 e$ T2 Y R2 _7 L: w! ~4 o
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Apologies for jumping into main topic.1 ]( n, f1 E$ @2 d3 M
Can you have a look at attached picture?
8 H" d; |8 Z( Dhttp://files.engineering.com/getfile.aspx?folder=a7879b3a-d0d7-459f-b9ac-829eb08891da&file=surf_perpendicularity.JPG4 w6 C' D. ^- n. b9 ^: D$ {' F0 p
How big can those perpendicularity tolerance values be, assuming they both have to be equal? Is there any limit or not? Thanks.
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- X( t/ F1 t' k( w" H6 @fsincox (Aerospace) | 9 Mar 12 9:15
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I believe it is acceptable to use a space between to pins say as a feature of size, right?5 V# L+ u" Y0 ]8 `" B0 R ^) I" Y
Frank
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CheckerHater (Mechanical) | 9 Mar 12 9:29
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Frank,
( D( [4 l: J: w Y( }$ F% J! T' aYes, but it will make them more ambiguous, than 2 FOS with position requirement, right?' R% e( F5 o# D* N6 c5 X! Y% } [# n- R
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What do YOU think?
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CheckerHater (Mechanical) | 9 Mar 12 10:03 0 x: N& U9 x4 P& V
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pmark,
1 w A9 x2 Y! [, `! yYou are a genius - I think this is exactly what OP was asking: do you use basic dimension to control perpendicularity of parallel elements.
& G6 ? k4 u6 N8 u1 g$ Y. \I would use basic dimension with profile to control the whole contraption. That will also make it less ambiguous.
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- W& i5 J, `9 L0 ~1 Rpmarc (Mechanical) | 9 Mar 12 10:04 % Z' e# y1 D/ f$ q" Q1 [5 f. y
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CH,
1 l# e; S& V. M+ `You are asking what do I think about my sketch or about your modified version of my sketch? Or is your sketch showing only one of situations that may occur for my tolerancing scheme?
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fsincox (Aerospace) | 9 Mar 12 10:20
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Sure ideally all should be controlled, that is right out of the book. Frank5 A( h2 z- y! s- X
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CheckerHater (Mechanical) | 9 Mar 12 10:22
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Actually both (or all three?).
: L) u# p5 O8 r* M4 II feel like using direct dimensioning may create ambiguity here. There is a reason ISO calls it "two-point dimension".0 B; k! W% g0 ?9 S# h+ m
(See my post about using Profile) $ U# c0 b5 W9 ^. E& l* c, {8 S
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CheckerHater (Mechanical) | 9 Mar 12 10:36
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Frank,
B5 t$ }: K# D+ K& AOff-topic, but since you brought it up; have you ever seen round hole dimensioned to the edge rather than center?
( i5 H$ K! p0 \3 U0 TI did, I was even forced to do it myself, I still don't like it. ; u; f* l2 V: A- v) ^
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" V0 y3 U6 Q4 n2 ]% Lfsincox (Aerospace) | 9 Mar 12 10:55
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CH,
- \8 o5 b% i5 h6 z M! Z' T3 C2 Q! |, NAre you kidding? I cut my teeth on that. It is what I was looking to GD&T to help me escape from. ;)
( p% l$ k% A% Z5 cThis thread has confused me a bit with the whole perpendicularity zone centered, center implies a location. Seems like at least part of the perpendicularity zone must be in the location tolerance zone or you would just move it./ ^( { M/ D' j+ G+ F
Frank + Y+ V3 ~' M& S% k
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