Sectional Views. DFTG-1305 Technical Drafting by Prof. Francis Ha. Session 6. Geisecke s textbook: 14 th Ed. Chapter 7 p th Ed. Chapter 8 p.

Transcription

1 DFTG-1305 Technical Drafting by Prof. Francis Ha Session 6 Sectional Views Geisecke s textbook: 14 th Ed. Chapter 7 p th Ed. Chapter 8 p.326 Update:

2 What is this? An ugly rock? Sectional Views

3 A pretty rock? Sectional Views

4 An apple

5 Cutting

6 Application Sectional View

7 Sectioning 1. Sectional Views 2. Rules of Sections 3. Types of Sections 4. Advanced Topics

8 Sectional Views A sectional view or section looks inside an object. Sections are used to clarify the interior construction of a part that can not be clearly described by hidden lines in exterior views. By taking an imaginary cut through the object and removing a portion, the inside features may be seen more clearly.

9 The part is cut using an imaginary cutting plane. Creating a Section View

10 The part is cut using an imaginary cutting plane. Creating a Section View

11 Creating a Section View The unwanted portion is mentally discarded exposing the interior construction.

12 Notice how the cut material is shown. Section Example Notice how the cutting plane is indicated. Sectional view label

13 Lines Used in Section Views Section Lines Arrows point to the portion being kept. Shows where the part is being cut.

14 Visualizing Cutting-Plane Direction Correct and Incorrect Cutting-Plane Line Placement

15 Cutting Plane Lines Used in Section Views Cutting plane line is a thick line, 1mm, B

16 Lines Used in Section Views Cutting Lines: Cutting or section lines are used to indicate where the cutting plane cuts through the material. Cutting lines are thin lines, 0.3mm, HB Cutting lines are generally drawn at a 45 angle. Cutting line symbols (or patterns) are chosen according to the material of the object. (ANSI Y- 14)

17 Lines Used in Section Views Common section line symbols: (More section line symbols are found in the book)

18 Sectioning 1. Sectional Views 2. Rules of Sections: Four major rules

19 Rule 1: Rules of Sectioning A section lined area is always completely bounded by a visible outline.

20 Rule 2: Rules of Sectioning The section lines in all areas should be parallel. Section lines shown in opposite directions indicate a different part.

21 Rule 3: Rules of Sectioning All the visible edges behind the cutting plane should be shown.

22 Rule 4: Rules of Sectioning Hidden features should be omitted in all all areas of a section view. Exceptions include threads and broken out sections.

23 Sectioning 1. Sectional Views 2. Rules of Sections 3. Types of Sections The types of section used depend on the situation and what information needs to be conveyed.

24 Types of Sections a. Full Section b. Half Section c. Offset Section d. Aligned Section

25 Full section

26 Full Section

27 a. Full Section To create a full section, the cutting plane passes fully through the object. Used in many cases to avoid having to dimension hidden lines.

28 Exercise Full Section Given the top and right side views, sketch the front view as a full section. The material used is steel.

29 Fill in the visible lines in the front full sectional view

30

31

32 Section lines are bounded by visible lines Visible features behind the cutting plane are shown.

33 Half Section

34 Half Section

35 b. Half Section A half section exposes the interior of one half of an object while retaining the exterior of the other half.

36 Half sections are used mainly for symmetric objects or assembly drawings.

37 A centerline is used to separate the two halves. Hidden lines should not be shown on either half.

38 Exercise Full and Half Sections Given the front and right side views, sketch the top view as a full section and create a half sectioned front view. The material is brass.

39 Fill in the visible lines in the top full section view.

40 Fill in the section lines in the top full section view.

41

42 Fill in the section lines in the right side half section view.

43

44 Center line divides the halves No hidden lines

45 c. Offset Section An offset section is produced by bending the cutting plane to show features that don t lie in the same plane.

46

47 Exercise Offset Section Given the front and top views, sketch the three missing section views in their appropriate places. The material is cast iron.

48

49

50

51

52 In order to include angled elements in a section, the cutting plane may be bent so that it passes through those features. d. Aligned Section

53 Features are revolved to the projection plane, and then projected over. Aligned Section

54 Sectioning 1. Sectional Views 2. Rules of Sections 3. Types of Sections 4. Advanced Topics Two typical types

55 Broken Section

56 Broken Section

57 a. Broken Section Sometimes only a partial or broken out section is needed. Hidden lines are shown in the non-sectioned area of a broken section. Scale 2:1

58 b. Removed Section A removed section is one that is not in direct projection of the view containing the cutting plane. Not in projection path and size

59 b. Removed Section Removed section should be labeled with Name and Scale.

60 This Slide Show is available on the instructor s Learning Web: learning.hccs.edu/faculty/francis.ha