4 w, }" z9 G, g. C8 n+ G' h" S作者: 喀秋莎 時間: 2012-7-20 12:07 本帖最后由 喀秋莎 于 2012-7-20 12:09 編輯 , l% ?' f) o$ U2 A, R+ R- X) Y3 }- ~
Geometric Dimensioning and Tolerancing (GD&T) is a language used on mechanical engineering drawings composed of symbols that are used to efficiently and accurately communicate geometry requirements for associated features on components and assemblies. GD&T is, and has been, successfully used for many years in the automotive, aerospace, electronic and the commercial design and manufacturing industries.In today's modern and technically advanced design, engineering and manufacturing world, effective and accurate communication is required to ensure successful end products. Currently, ASME Y14.5-2009 is the accepted geometric dimensioning and tolerancing standard superseding ANSI Y14.5M-1994 used within the USA and ISO 1101-2004 is used outside of the the USA.Success oriented industries and organizations which, require accurate and common lines of communications between engineering, design, manufacturing and quality should consider geometric dimensioning and tolerancing (GD&T) as their mechanical drawing standard. Some advantages of GD&T (geometric dimensioning and tolerancing) are; 1 d$ h7 `; m; ?. Y
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1.Provides a clear and concise technique for defining a reference coordinate system (datum's) on a component or assembly to be used throughout the manufacturing and inspection processes. 7 ~+ A8 T4 `% \9 P9 Y
2.Proper application of geometric dimensioning closely dovetails accepted and logical mechanical design process and design for manufacturing considerations. $ T9 ^. ]' T% K7 I7 H) A- Y$ A: W7 N3.Geometric dimensioning dramatically reduces the need for drawing notes to describe complex geometry requirements on a component or assembly by the use of standard symbology that accurately and quickly defines design, manufacturing and inspection requirements. ! I, G( X. c( O) t" M* l: V
4.GD&T concepts such as MMC (maximum material condition) when applied properly will facilitate and simplify the design of cost saving functional check gages, manufacturing fixtures and jigs. " }" j: H5 N7 S" F/ a8 x4 EThe following ar common reasons one should apply GD&T principles: # j/ q3 B4 q. G' F' g1.Part features are critical to function or interchangeability. n) a: C+ S$ C7 g k2 t0 g Q( x5 c' e
2.When functional gauging techniques are desired. " e. X+ o1 B: p4 P! y3.When a common reference (origin) or datum is required to ensure communication is consistent between design, manufacturing and inspection. ; c* d0 x9 ~5 w* r) |0 l4.When a standard interpretation or tolerance is not already implied. , m; i8 Y& b0 e4 q( `1 Y$ ?' c0 m7 W% |
5.Simplify tolerance analysis. ! d# e* t0 A: g' t: T3 m9 y. J6.Replace complex or long geometry requirement description notes with a single geometric symbol. 作者: 原諒我今天 時間: 2012-7-21 10:11
憨老馬 發(fā)表于 2012-7-20 10:44 ; F. z& t1 G L3 t4 `, m. ~啊!人人都如樓主這么認真的話,那該多好。 * G H" B# H" D. p+ {* g( O: s3 N; y9 c
昨天我給單位的同事發(fā)了個電郵,內(nèi)容是:
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現(xiàn)在國內(nèi)基本上整個行業(yè)都浮躁的一塌糊涂。一些最基本的準則都沒人在意了。以前,我們只是技術上落后,但起碼大家還是認認真真的按規(guī)范做事,現(xiàn)在,我們連標準和規(guī)范都落后了,沒幾個人考慮這些了。看看以前一些國企的圖紙,再跟現(xiàn)在的比一下,感覺就是在倒退。從企業(yè)到個人,幾乎都把工程設計的一些基本原則丟掉了。美國人的優(yōu)勢在于高速的創(chuàng)新,德國人的優(yōu)勢在于認真,我們呢?看看整個行業(yè)的現(xiàn)狀,真讓人傷心。: H& L8 w* o* `) W1 S* i/ a- F 作者: 機械神話 時間: 2012-7-21 21:30
從圖紙標注公差來看,公差標注確實很重要,GD&T確實解釋得很清楚了,論壇不少版塊都以后討論,討論了幾年了。 4 P; i! F- m! O8 @2 f: K我感覺是,GD&T懂60%就夠了,再多就純粹是玩數(shù)學了,是質(zhì)檢的人在玩設計的人。% t* Z8 s0 H, n0 m2 h
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從機械設計來說,圖紙公差的標注的重要性應該不是最重要的的,原理設計,材料,功能實現(xiàn)遠比他重要。當然,硬是較真,圖紙公差也沒有什么不重要的理由。 % ]! J3 U- c- L- E- D0 p # w' |' L" b( c5 F1 z; ~很多初始設計,是根本不標公差或者忽略公差的,機器造出來了,原理實驗了,后續(xù)內(nèi)容才是如何設定合理公差,或者補充或者根據(jù)實際調(diào)試結(jié)果。! |" U; g. ]; h# F) q5 Y* n) ~