removed view

advertisement
2D DRAWING
REPRESENTATION
CHAPTER SIX
OBJECTIVES
1. Represent curved surfaces in multiview drawings
2. Show intersections and tangencies of curved and planar surfaces
3. Represent common types of holes
4. Show fillets, rounds, and runouts in a 2D drawing
5. Use partial views
6. Apply revolution conventions when necessary for clarity
7. Draw removed views and projected views
8. Show right- and left-hand parts
9. Project curved surfaces by points
10. Show and label an enlarged detail
11. Show conventional breaks
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
2
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Common Manufactured
Features
• Fillet
• Round
• Counterbore
• Countersink
• Spotface
• Boss
• Lug
• Flange
• Chamfer
• Neck
• Keyway/Keyseat
• Knurl
• Bushing
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
3
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Conventional Representations
Standard orthographic projections
don’t always show complex shapes as
clearly and simply as you may wish,
so certain alternative practices,
referred to as conventions, are
accepted.
Conventions are like rules for breaking
the rules. Note how these views are
projected
Orthographic Views of Intersecting
and Tangent Surfaces.
(Lockhart, Shawna D.; Johnson, Cindy M., Engineering Design
Communication: Conveying DesignThrough Graphics, 1st, ©
2000. Printed and Electronically reproduced by permission of
Pearson Education, Inc., Upper Saddle River, New Jersey.)
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
4
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
VISUALIZING AND DRAWING
COMPLEX CYLINDRICAL SHAPES
Steps
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
5
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
CYLINDERS WHEN SLICED
Cylinders are often machined to form plane or other types of surfaces.
Normal surfaces appear true shape in the view where the line of sight is
perpendicular to the surface. In the two other views that normal surface
appears on edge. The back half remains unchanged.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
6
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
CYLINDERS AND ELLIPSES
If a cylinder is cut by an inclined plane, the inclined surface is bounded by
an ellipse. This ellipse will appear as a circle in the top view, as a straight
line in the front view, and as an ellipse in the side view.
When a circular shape is shown inclined in another view and projected into
the adjacent view it will appear as an ellipse, even though the shape is a
circle.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
7
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
INTERSECTIONS AND TANGENCIES
Where a curved surface is tangent to a plane surface no line is drawn, but
when it intersects a plane surface, a definite edge is formed.
When plane surfaces join a contoured surface, a line is shown if they are
tangent, but not shown if they intersect.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
8
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Intersections of Cylinders
When the intersection is small, its
curved shape is not plotted
accurately because it adds little to
the sketch or drawing for the time it
takes. Instead it is shown as a
straight line.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
When the intersection is larger,
it can be approximated by
drawing an arc with the radius
the same as that of the large
cylinder.
9
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
FILLETS AND ROUNDS
A rounded interior corner is called a fillet. A rounded exterior
corner is called a round.
Rounds on a CAD Model of a
Design for a Three-Hole Punch
Fillets on a CAD Model.
(Courtesy of Douglas Wintin.)
(Courtesy of Ross Traeholt.)
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
10
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
RUNOUTS
Small curves called runouts are used to represent
fillets that connect with plane surfaces tangent to
cylinders.
Runouts from different filleted
intersections will appear
different owing to the shapes of
the horizontal intersecting
members.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
11
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
CONVENTIONAL EDGES
There is a conventional way of showing rounded and filleted edges for
the sake of clarity. Added lines depicting rounded and filleted edges.
Rounded and filleted intersections eliminate sharp edges and can make it difficult to
present the shape clearly.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
12
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
NECESSARY VIEWS
What are the absolute minimum views
required to completely define an object?
One-View Drawing
Two-View Drawing
Three-View Drawing
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
13
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
PARTIAL VIEWS
A view may not need to be complete but needs to show what is necessary to clearly
describe the object. This is called a partial view and is used to save sketching
time and make the drawing less confusing to read.
OR
You can use a break line to limit the partial view…
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
14
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Showing Enlarged Details
When adding a detail,
draw a circle
around the features
that will be included in
the detail
Place the detail view on the
sheet as you would a removed
view. Label successive details
with the word DETAIL followed
by a letter, as in DETAILA,
DETAIL B,
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
15
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Conventional Breaks
To shorten the view of a long object, you can use break lines…
Using a break to leave out a portion of the part, but allows the scale for the ends
to be increased to show the details clearly.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
16
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
ALIGNMENT OF VIEWS
Always draw views in the “standard” arrangement...
Because CAD makes it easy to move whole views, it is
tempting to place views where they fit on the screen or
plotted sheet and not in the standard arrangement. This
is not acceptable.
3D CAD software that generates 2D drawing views as
projections of the 3D object usually has a setting to
select from third-angle or first-angle projection. Check
your software if you are unsure which projection methods
are available.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
17
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
REMOVED VIEWS
A removed view is a complete or partial view removed to another place on the sheet
so that it is no longer in direct projection with any other view.
Removed View Using
View Indicator Arrow
Removed View Using
Viewing-Plane Line
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
18
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
RIGHT-HAND AND LEFT-HAND PARTS
Often, parts function in pairs of similar opposite parts, but opposite
parts can rarely be exactly alike.
On sketches and drawings a left-hand part is noted as LH, and a right-hand part as RH.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
19
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
REVOLUTION CONVENTIONS
Regular multiview projections are sometimes awkward, confusing, or
actually misleading.
Revolutions like these are
frequently used in connection
with sectioning. Revolved
sectional views are called
aligned sections.
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
20
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Common Hole Features Shown in
Orthographic Views
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
21
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Common Features Shown in Orthographic
Views
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
22
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Common Features Shown in Orthographic
Views Continued…
Technical Drawing with Engineering Graphics, 14/e
Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman
23
© 2012, 2009, 2003, Pearson Higher Education,
Upper Saddle River, NJ 07458. • All Rights Reserved.
Download