机械设计基础A课件：第 二 讲 表达机件的常用方法-I

1、1,第 二 讲 表达机件的常用方法-I Fundamental methods for representation of mechanical parts,机械图样的五种基本表示法 Five basic methods for mechanical part drawing： 视图 Views 剖视图 Sectional Views 断面图Cross-Sections 局部放大图Local Enlarged Views 简化画法,技术制图国家标准GB/T 4458.12002 规定,2,一、基本视图Principal Views, 右视图 Right, 主视图 Main (Front) 俯视

2、图 Top 左视图 Left, 后视图 Back, 仰视图 Bottom, 形成Generation,从右向左投射,从下向上投射,从后向前投射,2.1 视图Views,表达机件外部结构形状 Representing Exterior construction,3, 六个投影面的展开 Open the Projection Box,4, 六面视图的投影对应关系 Relations between six views,上Top,下Bottom,左Left,右Right,右 Right,左Left,度量对应关系 ：仍遵守“三等”规律 Rule of Tri-equality, 方位对应关系：,主视

3、Main,俯视 Top,仰视Bottom,左视 Left,右视 Right,后视 Back,除后视图外，靠近主视图的一边是物体的后面，远离主视图的 一边是物体的前面。 All views but back view have the back side of the object close to the main view and front side of the object away from the main vies.,5,完成所给物体的其余四个基本视图，并徒手画斜二轴测图。 Complete the other four principal views of the given

4、object( front and top views）,sketch the cabinet drawing freehand.,这不是斜二轴测 Not Cabinet drawing,6,二、向视图Reference Arrow Views,向视图是可自由配置的视图 Freely Positioned Views, 在向视图的上方标注大写字母，在相应视图附近用箭头指明投射方向，并标注相同的字母。 Each freely positioned view should be identified by a capital letter( say ,A) placed immediately a

5、bove the view and the same letter is placed near the arrow indicating the direction of projection in the relevant view.,7,在理解向视图这一概念及其配置法时必须注意，可以自由配置的向视图，自由是不能超越一定限度的The freedom should be limited：,不能倾斜投射，应当正射。如果倾斜投射则所得不再是向视图，而是斜视图。The projection should be right not oblique or the view would be an in

6、clined view.,不能只画出部分图形，必须完整画出投射所得图形。否则为局部视图而非向视图。The whole projection should be drawn or the view would be local view.,不能旋转配置，即不能是相应基本视图旋转后的图形。否则不再是向视图，而是辅助视图了。The reference arrow view cannot be rotated or it would be an auxiliary view.,8,三、局部视图 Local Views,将物体某一部分向基本投影面投射所得的视图。 View by projecting o

7、f local construction of the whole object,注意事项Note ：,用带字母的箭头指明要 表达的部位和投射方向， 并注明视图名称。Reference arrow and capital letter,局部视图的范围用波浪 线表示。当表示的局部 结构是完整的且外轮廓 封闭时，波浪线可省略。 Wavy or zigzag line confine,局部视图可按基本视图 的配置形式配置，也可 按向视图的配置形式配 置。Local view can be placed in the same way as the principal or the reference

8、 arrow view.,9,10,四、斜视图Inclined Views,问题：当物体的表面与投影面成倾斜位置时，其投影不反映实形。Problem：The Projection of inclined surface of object doesnt show the true shape., 增设一个与倾斜表面平行的辅助投影面。 Add an auxiliary projection plane parallel to the inclined surface.,解决方法Solution：, 将倾斜部分向辅助投影面投射。Project the inclined part to the au

9、xiliary projection plane.,斜视图是物体向不平行于基本投影面的平面投射所得的视图。用于表达机件倾斜结构的外形。 Inclined views are projections of object onto a plane not parallel to any principal plane of projection. Inclined Views are used for the exterior construction of inclined part of the object.,11,A,斜视图的画法Drawing,注意事项Note：,绘制斜视图时，通常只画出

10、倾斜部分的局部外形，而断去其余部分，通常按投射方向放置和标注。Usually only the inclined part is drawn in inclined view . 斜视图的断裂边界用波浪线或双折线绘制 Wavy or zigzag line is used to the border. 允许旋转配置，但需注明。 Inclined view may be rotated to a more convenient position .,箭头指明旋转方向，字母靠近箭头一侧 Letter placed near the arrow which indicates the rotatin

11、g direction,旧标注为“A向旋转”,12,斜视图旋转配置时，旋转方向和角度的确定应考虑便于看图。旋转符号的箭头指向与旋转方向一致。旋转角度不大于45。视图名称大写拉丁字母在箭头端，需要给出旋转角度时，角度写在字母之后。 How to rotate the inclined view depends the convenience of understanding. The rotation angle usually is less than 45 . Rotation angle should be written after the Letter if necessary.,13

12、,作物体的A向局部视图和B向斜视图 Construct the partial view A and the inclined view B of the object,14, 视图小结 Conclusion on Views,基本视图,向视图,局部视图,斜视图,六面视图,六面视图,局部图形,完整图形,局部图形,完整图形,固定配置、不标注,任意配置、标注,基本视图方式配置,向视图方式配置,投射方向或旋转 配置、标注,视 图,15,2.2 剖视图 Sectional Views,问题： 当机件的内部形状较复杂时，视图上将出现许多虚线，不便于看图和标注尺寸。Problem: The numerou

13、s dash lines which show the complicated interior construction make the drawing difficult to interpret.,解决办法Solution？,采用剖视图 Sectional view,16,17,18,一、剖视图的概念 Concept of Sectional Views, 剖视图的形成 Generation,假想用一剖切面将机件剖开，移去剖切面和观察者之间的部分，将其余部分向投影面投射，并在剖面区域(切削平面与机件接触的面)内画上剖面符号。By imagining the object to be c

14、ut by a cutting plane and removing the portion near the observer, we project the remaining portion and fill the section area (the surfaces touched by the cutting plane )with section lines .,19,2.剖视图的画法 Drawing, 确定剖切面的位置 Define the cutting plane, 想象哪些部分材料被切到？剖面区域的形状？哪些部分投影时可看到？Imagine removed half, s

15、ection area and the visible ？, 在剖面区域内画上剖面符号。Fill the section area with section lines.,虚线不画 Not dash lines any more,20,A - A,3.剖视图的标注 Label the sectional views, 剖切符号 :表示剖切面起、迄和转折位置（用粗实线表示）及投射方向（用箭头表示） 。 Section signs show how the cutting plane goes through the object (thick solid lines) and the direc

16、tion of projection (by arrow) ., 剖视图的名称。大写拉丁字母在剖视图上方。为便于读图时查找，应在剖切符号附近注写相同的字母。Name of the section view by capital letter., 剖切线：指示剖切面的位置 (细点画线)。一般可省略。 Cutting Plane lines are dot-and-dash lines which are usually omitted.,21,22,剖切平面可以是倾斜的斜剖视图 Inclined views in section,23,当剖视图按投影关系配置，中间又无其他图形隔开时，可省略表示投

17、射方向的箭头The arrows can be omitted when the section view placed by the default projection direction,省略标注投射方向的剖视图Section view without any label,24,当单一剖切平面通过机件的对称或基本对称面，切剖视按投影惯性配置，中间又无图形隔开时，则不必标注。All the labels can be omitted when the section view with single cutting plane is placed by the default projec

18、tion direction,省略标注的剖视图 Section view without any label,25,在剖视图中的细薄构件,THIN MEMBERS IN SDCTIONAL VIEWS,对于机件的肋板，如按纵向剖切，肋板不画剖面符号，而用粗实线将它与其邻接部分分开。横向剖切肋板则画出剖面线。Rib should be separated by thick solid lines but not section-lined if the cutting plane cuts along the center plane of the rib ,while section-line

19、d if the cutting plane passes crosswise through the plate.,不正确Incorrect,正确Correct,正确Correct,26,选择剖切面位置时，一般不与轮廓线重合。必要时，也允许紧贴机件表面进行剖切，此时，该表面不画剖面线。Cutting plane doesnt coincide with contour surface. If necessary, The surface should be drawn without section lines,沿表面剖切的剖视图 Section view with cutting plan

20、e along the surface,27,剖面符号,SYMBOLS FOR SECTIONS,金属材料 Metallic material,非金属材料 Nonmetallic material,木材(纵剖面) Wood（longitudinal Section）,木材（横剖面） Wood (Transverse section),木制胶合板 Plywood,混凝土 Concrete,砖 Brick,电气绕圈绕组 Electric windings,玻璃及供观察用的 其他材料 Glass and other transparent materials for observation,液体 L

21、iquids,格网 Grid,4. 画剖视图的注意事项, 剖切平面的选择：通过机件的对称面或轴线且平行或垂直于投影面。The cutting plane usually through the symmetry or axis and parallel or perpendicular to the projection plane., 剖切是一种假想，其它视图仍应完整画出，并可取剖视。Imaginary cutting doesnt affect other views,29,剖切面后方的可见部分要全部画出。The feature behind cutting plane should be

22、 drawn.,错误 Incorrect,正确 Correct,30,31,在剖视图上已经表达清楚的结构,在其它视图上此部分结构的投影为虚线时,其虚线省略不画。但没有表示清楚的结构，允许画少量虚线。Adding hidden lines to a section view complicated the drawing, defeating the purpose of clarifying with a section，So a minimum number of hidden lines are needed to represent features other than the pri

23、mary one shown by the section.,32, 不需在剖面区域中表示材料的类别时，剖面符号可采用通用剖面线表示。通用剖面线为与主要轮廓或剖面区域的对称线成45角的细实线；同一物体的各个剖面区域，其剖面线画法应一致。Different section line symbols can be used to represent various types of materials. However, the general purpose section line symbol used in most section view drawings is thin solid

24、lines being drawn at a 45 degree angle . If the visible outline to be sectioned is drawn at a 45 degree angle, the section lines are drawn at a different angle, such as 30 degrees.,不好 Poor,好 Good,不好 Poor,好 Good,33,二、剖视的种类 Section view types,1.全剖视Full Section,用剖切面完全地剖开物体所得的剖视图。 A full section view is

25、 made by passing the cutting plane fully through the object.,外形较简单，内形较复杂，而图形又不对称时。Full section is used to represent object which has simple exterior feature but complicated interior and nonsymmetrical.,适用范围：,34,不能清楚表达外形 Cant tell the external feature clearly.,存在什么问题？ What is the problem?,35,解决办法Solu

26、tion：,以对称线为界,一半画视图,一半画剖视。Cutting plane passes through half way through the object. Half section and half external feature are drawn symmetric to the axis.,2. 半剖视 Half Section,已表达清楚的 内形虚线不画 Hidden lined are omitted,分界线为中心线 Center line to separate the sectioned half from the unsectioned half of the ha

27、lf section view.,36,适用范围：,内、外形都需要表达，而形状又基本对称时。 Half section views are most often used on objects that are symmetrical and complicated in both interior and external.,BB,半剖视 Half Section,37,3. 局部剖视 Broken-out section,A,A,AA,BB,用剖切平面局部地剖开物体所得的剖视图。A broken-out section is used to show interior features o

28、f a part by breaking away some of the object.,局部剖视部分义波浪线与周围断开。A wavy break line separates the sectioned from un-sectioned half of the view.,38,3. 局部剖视Broken-out section,BB,A,A,AA,可用双折线代替波浪线。 The break lines can be zigzag lines.,39,适用范围：,局部剖是一种较灵活的表示方法，适用范围较广。Broken-out section is a rather flexible a

29、nd widely used method.,只有局部内形需要剖切表示时。 When the interior feature of only part of an object,40,实心杆上有孔、槽时，应采用局部剖视。 Solid shaft with only local hole or slot.,41, 当对称机件的轮廓线与中心线重合， 不宜采用半剖视时。When contour line coincides with center line of a symmetrical object , broken-out section view is used instead of the half section.,不好 POOR,好 GOOD,42, 当机件的内外形都较复杂，而图形 又不对称时。Broken-out section view used for non-symmetrical object w