2012第4講尺寸注法-II

1、第 四 講 尺寸標注2 Dimensioning2組合體尺寸標注 Composite solid dimensioning尺寸標注的一些規(guī)則 Some conventional rules常見機件結構尺寸標注 Dimensioning of general features一、標注尺寸的基本要求 Basic requirements4.1 標注尺寸的基本要求與規(guī)則Basic requirements for dimensioning 正確Correct：完全Complete：要符合國家標準的有關規(guī)定。Drawing of dimensions according to Standards or

2、 conventions.要標注制造零件所需要的全部尺寸，不遺漏，不重復。All dimensions for manufacturing without missing and redundant清晰Clear：尺寸布置要整齊、清晰，便于閱讀。Dimensions layout should be clear and convenient for reading合理Rational：標注的尺寸要符合設計要求及工藝要求。Dimensions represent requirements of design (function) and manufacturing 以毫米為單位，如采用其它單位時

3、，則必須注明單位名稱。Dimensions are given in millimeters without adding mm and the other units should be shown. 圖中所注尺寸為零件完工后的尺寸。Dimensioning part as it machined completely 每個尺寸一般只標注一次，并應標注在最能清晰地反映該結構特征的視圖上。Each dimension can be given only once ,generally , and on the view which demonstrate the feature most cl

4、early.二、標注尺寸的基本規(guī)則Basic rules 尺寸數(shù)值為零件的真實大小，與繪圖比例及繪圖的準確度無關Dimensions indicate the true size of the object and irrespective of the scale and drawing accuracy.三、尺寸三要素 Three key elements of a dimension 尺寸界線 尺寸線 尺寸數(shù)字C1.510C1.5162035尺寸數(shù)字Text數(shù)字高度3.5毫米尺寸線Dimension line這些間距7毫米最好不超過10毫米。尺寸界線超出箭頭約2毫米尺寸界線Extensi

5、on line16允許Fine10不可以Incorrect 用形體分析法將組合體分解為若干個基本體和簡單體，在形體分析的基礎上標注三類尺寸。Break down the complex part into basic geometric components , then give three types of dimensions: 定形尺寸 Size dimensions確定各基本體形狀和大小的尺寸。 Dimensions which show the shape and sizes of the basic geometric components. 定位尺寸 Location dime

6、nsions確定各基本體之間相對位置的尺寸。Dimensions which locate the basic components with each other. 要標注定位尺寸，必須先選定尺寸基準。零件有長、寬、高三個方向的尺寸，每個方向至少要有一個基準。Location dimensions must be measured from properly selected datums. At least one datum should be determined along each directions of the part : along length ,along width

7、 and along height directions.一、基本方法Primary method4.2 組合體的尺寸標注方法 Dimensioning of complex part ( 總體尺寸) (Overall dimensions)零件長、寬、高三個方向的最大尺寸。(不一定需要直接標注)The maximum sizes in the directions of length, width and height which may be inferred by the other dimensions. 總體尺寸、定位尺寸、定形尺寸可能重合，這時需作調整，以免出現(xiàn)多余尺寸。Adjus

8、tment should be made if the three types of dimensions may be coincide to avoid redundant dimensions. 通常以零件的底面、端面、對稱面和軸線作為基準。Datums can be the base, a main side face, symmetry plane ,or center line.二、一些常見基本體的定形尺寸30102030201025143025143025S25三、截切后基本體的定形尺寸標注方法Dimensioning of truncated solid標注基本體的尺寸，確定截

9、平面的位置。Dimension the full solid and locate the cutting plane.不標注截交線的尺寸。 Dont dimension the intersections.SR18182056505220565020不標注截交線的尺寸。 Dont dimension the intersections.四、一些常見形體的定位尺寸 Locating dimensions of some common-used features 一組孔的定位尺寸 group of holes 長方體的定位尺寸 Cube 圓柱體的定位尺寸 Hollow cylinder基準基準基

10、準基準基準Datum基準基準基準R84030252016403016相貫形立體的尺寸標注 dimensioning of solid with intersecting features不標注相貫線的尺寸。 Dont dimension the intersections.151212不以回轉體的外形線作為定位基準Contour line cannot be used as the datum既是定形尺寸也是定位尺寸This dimension determine both size and location7530304050 45100851051907518068559011090五、標

11、注示例： 形體分析 Shape analysis。總體尺寸,調整 Overall dimension and adjustment if necessary 逐個標注每一基本形體的定形、定位尺寸。Dimensioning size and location of the basic geometric solid one by one基準基準基準41216例1：RRRRRR4.3 尺寸的清晰布置 The clarity of dimensions一、應盡量標注在視圖外面，以免尺寸線、尺寸數(shù)字與視圖的輪廓線相交。Place dimensions outside a view as much as

12、 possible for clarity。好Good不好Poor二、同心圓柱的直徑尺寸，最好注在非圓的 視圖上。Diameters of concentric cylinders are best placed on the linear view.好Good不好Poor44AAAAAA4RAAAAAA4R三、相互平行的尺寸，應按大小順序排列，小尺寸在內，大尺寸在外。Parallel dimensions are arranged as the larger outside of the smaller one.好Good不好Poor四、內形尺寸與外形尺寸最好分別注在視 圖的兩側。Exter

13、ior and interior dimensions are best placed separately on the both side of the view.好Good不好Poor4.4 尺寸標注必須合理 Reasonable dimension 所謂合理就是標注尺寸時，既要滿足設計要求又要符合加工測量等工藝要求。Reasonable dimensioning meets design , machining and measurement requirements.一、正確地選擇基準 Correct datum 設計基準Design datum 工藝基準 machining dat

14、um設計時用以確定零件在部件中的位置的基準。Datum used to locate the part in the assembly during design period加工或測量時用以確定零件位置的基準。Datum used to locate the part during its machining or measuring 設計基準Design datum設計基準Design datum工藝基準Machining datum例如：AAAA二、主要的尺寸(或功能尺寸)應直接注出Key dimension should be given directly 主要尺寸指影響產品性能、工作

15、精度和配合的尺寸。Key dimensions means those that influence the performance, working accuracy and assembling of the part. 非主要尺寸指非配合的直徑、長度、外輪廓尺寸等。Secondary dimensions include the diameter , length or contour that does not have to match with the other featurescbcd正確Correct錯誤Incorrectbcdebcd三、避免出現(xiàn)封閉的尺寸鏈 Avoid c

16、lose dimensions loop 長度方向的尺寸 b、c、 e 、d 首尾相接，構成一個封閉的尺寸鏈。Dimensions b, c, e and d form a close loop 由于加工時，尺寸 c、d、e 都會產生誤差，這樣所有的誤差都會積累到尺寸 b上，不能保證尺寸 b 的精度要求。All the machining errors added to dimensions c, d and e would be accumulated on dimension b such that the accuracy of b could not be guaranted. 錯誤I

17、ncorrect 正確Correct262036458C1 1016四、應盡量符合加工順序 Consider the machining order加工順序Machining order262036558C1 1016加工順序Machining order1015五、應考慮測量方便 Dimensioning to measure conveniently 好Good不好Poor不好Poor好Good例：標注組合體尺寸 Eg. Dimensioning1.底板Base board2.圓筒hollow cylinder3.凸臺bulge4.支撐板support board5.肋板rib六、尺寸配置

18、合理 Dimensioning reasonably 功能尺寸應直接注出。Key size dimensioned directly 同一要素的尺寸應盡可能集中標注， 如孔的直徑和深度、槽的深度和寬度等。Place all dimensions of one feature together if possible, like the diameter and depth of on hole, or the depth and width of one groove. 盡量避免在不可見的輪廓線上標注尺寸。Dimensioning on hidden lines should be avoided.作業(yè) 注尺寸：P69，P70補充 ：典型結構的尺寸標注 有一些典型結