jain_chap4_Summer08 - IV. Sections 4.1. Cutting Planes...

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Unformatted text preview: IV. Sections 4.1. Cutting Planes & Cutting Plane Lines Sections UCLA MAE94 Using a cutting plane to cut an object to reveal its internal features by orthographic projection of the features onto the cutting plane. Cutting-plane lines Typical cutting-plane lines used to represent sections. For instance, the cutting plane marked B-B in a drawing will produce a section view labeled B-B in the same drawing. 1 Section Views UCLA MAE94 B B 2 Cutting Planes B B UCLA MAE94 3 Cutting Plane Line Types UCLA MAE94 4 Cutting Planes Lines and Section Location UCLA MAE94 Always View Immediately Behind Arrows 5 UCLA MAE94 4.2. Section Symbols 6 Standard Section Symbols UCLA MAE94 7 Special Section Symbols UCLA MAE94 8 UCLA MAE94 4.3. Section Line Practices 9 UCLA MAE94 10 UCLA MAE94 11 Section Line Practices UCLA MAE94 12 UCLA MAE94 13 UCLA MAE94 14 Outline Sectioning UCLA MAE94 15 4.4. Full Sections UCLA MAE94 Full Section: A full section is formed by a cutting plane that passes completely through the part. 16 Full Section UCLA MAE94 17 Full Section Review UCLA MAE94 18 Exercise: Full section problem Draw full section view of the part UCLA MAE94 19 Exercise: Full section problem Draw the full section of the given part UCLA MAE94 20 4.5. Half Sections UCLA MAE94 Half Section: The cutting plane of a half section passes halfway through the object, which results in a sectional view that shows half the outside (not regular orthographic views) and half the inside of the object. Hidden lines are omitted unless they are needed to clarify the view. 21 Half Sections Note: No hidden lines shown on the drawing of the outside half UCLA MAE94 Optional Arrow 22 UCLA MAE94 23 UCLA MAE94 24 UCLA MAE94 25 Exercise: Half Section Problem Use the front and right side views below to sketch the top view as a half section UCLA MAE94 26 Half Section Result UCLA MAE94 27 4.6. Broken-Out Sections When it is necessary to show only a portion of the part in section, the sectioned area is limited by a freehand break line, and the section is called a broken-out section. UCLA MAE94 28 UCLA MAE94 29 UCLA MAE94 30 UCLA MAE94 31 4.7. Revolved Sections UCLA MAE94 Revolved Section: An axis of revolution is shown in a given view. The cutting plane would appear as an edge in the given view if it were shown. The vertical section is revolved so that the section can be seen true size in the given view. Object lines are discontinued by break lines and are not drawn through the revolved section. 32 UCLA MAE94 33 UCLA MAE94 34 UCLA MAE94 35 Revolved Sections UCLA MAE94 36 4.8 Removed Sections Removed sections show the special or transitional details of a part. They are like revolved sections, except that they are placed outside the principal view. In some cases, removed sections are drawn to a larger scale. 37 UCLA MAE94 38 UCLA MAE94 39 4.9. Offset Sections To include features of a part not located in a straight line, the cutting plane may be stepped, or offset, at right angles to pass through these features. Offset sections reduce the number of required sections for a complicated part. An offset section is drawn as if the offsets were in one plane, and the offsets are not indicated in the section view. 40 Note: Do not show offset lines in the section views UCLA MAE94 41 UCLA MAE94 42 UCLA MAE94 43 Exercise: Offset Section Problem Replace the front view with the required offset section UCLA MAE94 44 4.10. Assembly Sections Assembly sections show two or more mating parts in section. Usually rivets, pins, screws, bolts, nuts, shafts, cylinders, balls, etc. are not sectioned lined in assembly sections. UCLA MAE94 45 UCLA MAE94 46 UCLA MAE94 47 4.11 Part Not Hatched UCLA MAE94 48 4.12. Thin Parts - Webs, Ribs, Spokes, and Lugs UCLA MAE94 Thin solid shapes are sometimes represented without section lining or are sometimes double sectioned. 49 Section Conventions on Thin Parts UCLA MAE94 50 UCLA MAE94 51 UCLA MAE94 52 UCLA MAE94 53 UCLA MAE94 54 4.12. Aligned Sections If the true projection of a part results in foreshortening or requires unnecessary drawing time, inclined elements such as lugs, ribs, spokes, and arms are rotated into a plane perpendicular to the line of sight of the section. Cutting-plane lines are normally omitted for rotated features. This type of section is called an aligned section. 55 Aligned Parts Section Conventions on Symmetrical Features UCLA MAE94 56 UCLA MAE94 57 UCLA MAE94 58 UCLA MAE94 Aligned Section Through a Rib. An alternative method of sectioning a rib with double-spaced section lines is also shown. 59 UCLA MAE94 60 UCLA MAE94 61 UCLA MAE94 62 Exercise: Aligned Sections Symmetrical ribs and holes UCLA MAE94 63 Exercise: Spokes in section UCLA MAE94 64 UCLA MAE94 65 UCLA MAE94 66 Exercise: Section the right side view of the part UCLA MAE94 67 Exercise: Drawn an offset section of the part. Pass the cutting plane through the two holes and the slots. UCLA MAE94 68 ...
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