sectional view.ppt
DESCRIPTION
Sectional views in engineering drawings for mechanical engineers.TRANSCRIPT
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
MID TERM EXAM!!!
Don’t press the PANIC button!
MTS 242 - Computer Aided Drawing (Fall 2009)
Sectional View
MTS 242 - Computer Aided Drawing (Fall 2009)
Motivation
MTS 242 - Computer Aided Drawing (Fall 2009)
Motivation
MTS 242 - Computer Aided Drawing (Fall 2009)
Sectional View of Valves & Cylinder of 100 HP Engine
Motivation
MTS 242 - Computer Aided Drawing (Fall 2009)
Introduction
• A sectional view represents the part of an object which remains after a portion has been removed.
• Used to show hidden shape or form
• Will help to clarify what would normally be shown as hidden detail
• Only solid material being cut is sectioned
• The section is obtained by cutting the component into two parts at some good points
• Sectioning symbol or hatching should be used to indicate the part that has been cut.
MTS 242 - Computer Aided Drawing (Fall 2009)
Types
• Longitudinal Section – Lengthwise
• Cross Section – cross wise
– FULL
– HALF (half way across a symmetric object)
– BROKEN (partial, when a full and half section is not needed)
– REVOLVED (REMOVED)
– OFFSET
– ALLIGNED
– RIB & WEB
– THIN
MTS 242 - Computer Aided Drawing (Fall 2009)
How To?
Part is CUT with an imaginary plane.
MTS 242 - Computer Aided Drawing (Fall 2009)
How To?
MTS 242 - Computer Aided Drawing (Fall 2009)
How To? - Section Example
Notice how the cutting plane is indicated.
Notice how the cut material is shown.
Sectional view label
MTS 242 - Computer Aided Drawing (Fall 2009)
Lines Used in Section Views
• Cutting Plane Line: Used to show where the object is being cut.
– (Phantom line type)
MTS 242 - Computer Aided Drawing (Fall 2009)
How To? - Lines Used in Section Views
Shows where the part is being cut.
Arrows point to the portion being kept.
Section Lines
MTS 242 - Computer Aided Drawing (Fall 2009)
Lines Used in Section Views
• Section Lines: Section lines are used to indicate where the cutting plane cuts the material.
– Section lines are thin lines. – Section line symbols are chosen according to the material of
the object – Section lines are generally drawn at a 45 angle.
MTS 242 - Computer Aided Drawing (Fall 2009)
Introduction - Hatching
Thin continuous line.
Drawn at 45° to the horizontal, in either the right or left direction.
MTS 242 - Computer Aided Drawing (Fall 2009)
Material Symbols
Figure 7.33 (ANSI Standard)Page 169
MTS 242 - Computer Aided Drawing (Fall 2009)
Adjacent Parts
MTS 242 - Computer Aided Drawing (Fall 2009)
How To? - Summary
• Section cutting planes are denoted by chain line
• Arrowheads indicate the direction of viewing
• The section view is identified by 'SECTION A-A'
MTS 242 - Computer Aided Drawing (Fall 2009)
How to? - Example.
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules & Exceptions
As general rule, all material cut by a cutting plane is hatched,
except
for
web, shafts, bolts, rivets, keys, pins, and similar parts
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules of Sectioning
• Rule 1:
A section lined area is always completely bounded by a visible outline.
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules of Sectioning
• Rule 2:
The section lines in all areas should be parallel. – Section lines shown in opposite directions indicate a different
part.
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules of Sectioning
• Rule 3: All the visible edges behind the cutting plane should be shown.
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules of Sectioning
• Rule 4:
Hidden features should be omitted in all areas of a section view.
– Exceptions include threads and broken out sections.
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules & Exceptions - Example
MTS 242 - Computer Aided Drawing (Fall 2009)
Rules & Exception - Example
MTS 242 - Computer Aided Drawing (Fall 2009)
Sectioning
Types of Sections
MTS 242 - Computer Aided Drawing (Fall 2009)
Types of Sections
• The type of section used depends on the situation and what information needs to be conveyed.
• Types of sections– Full Section– Half Section– Offset Section– etc …
MTS 242 - Computer Aided Drawing (Fall 2009)
Full Section
MTS 242 - Computer Aided Drawing (Fall 2009)
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.
MTS 242 - Computer Aided Drawing (Fall 2009)
Exercise
• Given the top and right side views, sketch the front view as a full section.
– The material used is steel.
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the visible lines in the front full sectional view
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the section lines in the front full sectional view
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
Section lines are bounded by visible lines
Visible features behind the cutting plane are shown.
MTS 242 - Computer Aided Drawing (Fall 2009)
Orthogonal View of a Section
MTS 242 - Computer Aided Drawing (Fall 2009)
Isometric Full Section View Example
MTS 242 - Computer Aided Drawing (Fall 2009)
Half Section
1/2
MTS 242 - Computer Aided Drawing (Fall 2009)
Half Section
A half section exposes the
interior of one half of an object while retaining the exterior of the other half
MTS 242 - Computer Aided Drawing (Fall 2009)
Half Section
Half sections are used
mainly for symmetric objects or assembly drawings.
MTS 242 - Computer Aided Drawing (Fall 2009)
Half Section
• A centerline is used to separate the two halves.
• Hidden lines should not be shown on either half.
MTS 242 - Computer Aided Drawing (Fall 2009)
Exercise
• 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.
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the visible lines in the top full section view.
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the section lines in the top full section view.
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the visible lines in the right side half section view.
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the section lines in the right side half section view.
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
No hidden lines
Center line divides the halves
MTS 242 - Computer Aided Drawing (Fall 2009)
Isometric Half Section View
MTS 242 - Computer Aided Drawing (Fall 2009)
Orthogonal Section View
MTS 242 - Computer Aided Drawing (Fall 2009)
Offset Section
MTS 242 - Computer Aided Drawing (Fall 2009)
Offset Section
An offset section is produced by bending the cutting plane to show features that don’t lie in the same plane.
MTS 242 - Computer Aided Drawing (Fall 2009)
Offset Sectional View
Isometric view of an offset section
MTS 242 - Computer Aided Drawing (Fall 2009)
Orthogonal View of an Offset Section
MTS 242 - Computer Aided Drawing (Fall 2009)
Exercise
• Given the front and top views, sketch the three missing section views in their appropriate places. The material is cast iron.
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
MTS 242 - Computer Aided Drawing (Fall 2009)
Broken, Partial, & Revolved Sections
MTS 242 - Computer Aided Drawing (Fall 2009)
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.
MTS 242 - Computer Aided Drawing (Fall 2009)
Removed Section
Not in projection path
Removed sections should be labeled with a name and scale.
A removed section is one that is not in direct projection of the view containing the cutting plane.
MTS 242 - Computer Aided Drawing (Fall 2009)
Revolved Section
• The cross sectional shape of an object may be shown in the longitudinal view by means of a revolved section.
MTS 242 - Computer Aided Drawing (Fall 2009)
Revolved (Removed) Section
MTS 242 - Computer Aided Drawing (Fall 2009)
Shape Symbols
MTS 242 - Computer Aided Drawing (Fall 2009)
Aligned Section
MTS 242 - Computer Aided Drawing (Fall 2009)
Aligned Section
In order to include angled elements in a section, the cutting plane may be bent so that it passes through those features.
Advanced Topic
MTS 242 - Computer Aided Drawing (Fall 2009)
Conventions of Revolution
Features are revolved to the projection plane, and then projected over.
MTS 242 - Computer Aided Drawing (Fall 2009)
Exercise
• Given the front and un-revolved right side views, sketch the right side view as an aligned section using the conventions of revolution. The material is cast iron.
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the visible lines in the sectional view.
MTS 242 - Computer Aided Drawing (Fall 2009)
Fill in the section lines.
MTS 242 - Computer Aided Drawing (Fall 2009)
Notice how much clearer the sectional view is.
MTS 242 - Computer Aided Drawing (Fall 2009)
Ribs & Webs
MTS 242 - Computer Aided Drawing (Fall 2009)
Rib and Web Sections
Cutting plane passes through the web
No section lines in cut area of web
To avoid a false impression of thickness and solidity, ribs and webs are not sectioned
MTS 242 - Computer Aided Drawing (Fall 2009)
Rib and Web Sections
Cutting plane passes through the web
Section lines in cut area of web
If the cutting plane passes crosswise through the rib or web, we include section lines.
MTS 242 - Computer Aided Drawing (Fall 2009)
Non – Sectioned Parts
• It is common practice to show standard parts 'in the round' or un-sectioned.
– Nuts
– Bolts
– Rivets
– Shafts
– Screws
MTS 242 - Computer Aided Drawing (Fall 2009)
Thin Sections
• For extremely thin parts of less than 4 mm thickness, the parts should be shown in solid black or without section lines.
– Sheet metal
– Washers
– Gaskets
MTS 242 - Computer Aided Drawing (Fall 2009)
Best Practices
• Line Spacing
• Ribs
• Holes
• Spokes
}Read Examples From Text
MTS 242 - Computer Aided Drawing (Fall 2009)