AUTOCAD 3 FILE - Unesco

Transcription

UNESCO-NIGERIA TECHNICAL &
VOCATIONAL EDUCATION
REVITALISATION PROJECT-PHASE II
NATIONAL DIPLOMA IN
MECHANICAL ENGINEERING TECHNOLOGY
AUTOCAD 3
COURSE CODE: MEC 223
YEAR II- SEMESTER IV
THEORY/PRACTICAL
Version 1: December 2008
UNESCO-NIGERIA TECHNICAL &
VOCATIONAL EDUCATION
REVITALISATION PROJECT-PHASE II
NATIONAL DIPLOMA IN
MECHANICAL ENGINEERING TECHNOLOGY
AUTOCAD 3
COURSE CODE: MEC 223
YEAR II- SEMESTER IV
THEORY/PRACTICAL
Version 1: December 2008
TABLE OF CO NTENT
COVER PAGE
WEEK 1
1.0
REPRESENTING THE ISOMETRIC SCREW
THREADS ON DRAWINGS
WEEK 2
1.1
Using design center in AutoCAD
1.2
Task 1
2.0
REPRESENTING THE ISOMETRIC SCREW
THREADS ON DRAWING II
WEEK 3
WEEK 4
WEEK 5
WEEK 6
2.1
Using design center in AutoCAD
3.0
CONVENTIONS AND SYMBOLS
3.1
Technical Drawing Abbreviations & symbols
3.2
Mechanical Parts Abbreviations & symbols
3.3
Machine Parts Abbreviations & symbols
3.4
Standard Parts Abbreviations & symbols
3.5
Quiz 1
4.0
WORKING DRAWING
4.1
Introduction
4.2
Types of Working Drawings
4.3
Quiz 2
5.0
ASSEMBLY DRAWING
5.1
Sequence of Producing Assembly Drawing
5.2
Task 2
6.0
RULES AND FEATURES OF ASSEMBLY
DRAWING
6.1
Layout of Drawing
6.2
Part List
WEEK 7
WEEK 8
WEEK 9
WEEK 10
6.3
Dimensions
6.4
Task 3
7.0
ASSEMBLY DRAWING
7.1
Pin Joint Assembly
8.0
ASSEMBLY DRAWING
8.1
Screw Jack Assembly
9.0
ASSEMBLY DRAWING
9.1
Pulley Bracket Assembly
10.0 ASSEMBLY DRAWING
10.1 Clamp Assembly
WEEK 11
11.0 ENGINEERING DRAWING ANALYSIS
11.1 Solved Example 1
11.2 Solved Example 2
11.3 Quiz 3
WEEK 12
12.1 Guide Bracket with Inspection Plate
WEEK 13
13.1 Sliding Block Assembly
WEEK 14
14.1 Machine Vice Assembly
WEEK 15
15.1 Bracket and Glad Assembly
WEEK 1
1.0
REPRESENTING THE ISO METRIC SCREW THREADS ON
DRAWINGS
1.1
Using Design Center in AutoCAD
Metric Fasteners made easier with AutoCAD, you have the access to unlimited numbers
of conventions and symbols for different types of industries. You can insert and edit the
convention symbols as much as you want to suite the drawing.
You can log to design center from "Design Center" Command available at standard
toolbar as shown below
.
Once you click the design center bottom a file search window like the one below will
open.
From the folders list select
design center,
From the right window select
Fasteners-Metric.
Then open the block display,
From block display you can select the type of fasteners you want to use.
Now let us try to select the Hex Nut -10 mm,
Click the right click bottom, a short cut menu will allow you to insert the symbol with the
possibility of editing it.
Try to double the scale before inserting the Hex Nut, remember that the Hex Nut will be
inserted as an object you can not modify it before you explode it's lines
Although the drawing will not be precise after scaling, however using design library will
save you time and effort (Fig. 1).
Fig. 1
1.1 Task 1
1- Using AutoCAD Design Center assemble the two plates shown in (Fig. 29) use
M20 for the Hex Nut & Bolt.
Fig. 1.1
2- Try to draw a 2D engineering drawing of your own and add to it as many standard
parts needed (use design center).
WEEK 2
2.0
REPRESENTING THE ISO METRIC SCREW THREADS ON
DRAWINGS II
2.0
Using Design Center in AutoCAD II
Using AutoCAD design center assemble the two halves of coupling shown in (Fig. 2)
below, use M20 for the Hex Nut & bolt, also add suitable washers and spring washers. .
Fig. 2
WEEK 3
3.0
CONVENTIONS AND SYMBOLS
Different industries use different symbols and abbreviations in their drawings, this to
minimize time consumed in drawing and at the same time standardizes professional
dialog and communication.
3.1
Technical drawing Abbreviations & Symbols
Table (3.1.1 & 3.1.2), explains symbols and abbreviations commonly used in
engineering drawings.
Term
Abbreviation
Across flats
AF
Assembly
Centers
Center line on a view in
a note
Cylinder or cylindrical
ASSY
CRS
C
CL
CYL
Diameter (in a note)
Diameter (preceding a
dimension)
Dimension
Drawing
DIA
ø
DIM.
DRG
Figure
FIG.
Long
Machine
LG
MC
Material
Maximum
MATL
MAX
Not to scale
NTS
Number
Radius (in a note)
NO.
RAD
Radius (preceding a dimension)
Standard
R
STD
Table 3.1.1
3.2 Mechanical parts abbreviations & symbols
Table 3.1.2
3.3
Machine parts abbreviations & symbols
Table 3.1.3.
3.4
Standard parts Abbreviations & Symbols
Table 3.1.4
3.5
Quiz Sheet 1
1- Select from the right table the correct names of the conventional representations
in the left table, the first row is given as an example.
2- Select from upper table the correct abbreviation and fill the lower table.
A
B
C
D
1
ACROSS
FLAT
RADIUS
SCRAPE
DIAMETER
(Preceding a
dimension)
2
CLEARENCE
SPHERICAL
LONG
DRAWING
3
ASSEMBLED
STATED
ACROSS FACES
RIGHT HAND
4
DIAMTER
(in a note)
STANDARD
ASSEMBLY
CHAMFER
5
PLACED
SPECIFICATIONS
PITCH
CIRCLE
DIAMETER
CENTER LINE
6
CHAMFERED
DRAWN
SCREWED
LIGHT GAUGE
Abbreviation
No.
1
2
3
4
5
6
7
8
Abbreviation
AF
ASSY
ø
DIA
DRG
LG
R
RAD
WEEK 4
4.0
WORKING DRAWINGS
4.1
Introduction
A working drawing is the final constructed drawing produced in the design stage. After
that the drawing would be sent to the workshop floor for production. Thus, the drawing
should be precise and drawn to an appropriate scale and it usually includes a set of the
interrelated parts and details that are needed in production stage.
4.2
Types of working drawings
Working drawings can be divided into two main types, they are, Assembly drawings and
Detail drawings.
1) Assembly drawings
A complete assembly drawing is presentation of the product or structure put together,
showing all parts in their operational positions. The parts are logically connected
according to the designer specifications. (Fig. 4)
Fig. 4 - Assembly drawing
2) Detailed drawings
A detail drawing is used to magnify and focus on individual items in more details, this to
be helpful to the shop-floor personnel in producing each part precisely, and to be in
accordance with the designers requirements. (Fig.4.1)
Fig. 4.1– Detail drawing
3) Outline Assembly Drawings
Usually used when general idea of exterior shape of machine or structure is required and
contains only the principle dimensions (Fig. 4.2)
Fig. 4.2 - Outline Assembly Drawing
4) General Assembly Drawings
It shows the general arrangement of the machine or structure having the relative positions
of different parts in working order (Fig. 4.3).
Fig. 4.3 - General Assembly Drawing
5) Sub-Assembly
It is a drawing of a related group of parts and usually used to show the assembly of
complicated machinery for which it would be practically impossible to show all the
features on one drawing (Fig. 4.4)
Fig. 4.4 - Sub-Assembly Drawing
6) Exploded Assembly Drawing
Commonly drawn in isometric, these drawings are usually useful for persons who are not
trained to read Two Dimensional Drawings. (Fig. 4.5 and 4.6)
Fig. 4.5 - Exploded Assembly Drawing
.
4.3
Fig. 4.6 - Exploded Drawings
QUIZ 2
1) Name three (3) types of drawing used in engineering.
•
•
•
…………………..………
…………………………..
…………………………..
2) Name the command that is available in CAD that allows you to see all the sides of
the component easily?
3) What is the main feature of an exploded drawing?
WEEK 5
5.0
ASSEMBLY DRAWINGS
5.1
Sequence of producing Assembly Drawings
To be able to draw a complete assembly drawing Fig. (5) you should follow carefully the
below steps:
1- Study the application of the machine or structure
2- Try to match the dimensions and understand the relationship between parts
3- Study carefully the assembly guide given to identify the relationship between
parts, in case no assembly guide is given try to draw one to help you in your
assembly.
Fig. 5- Assembly Guide
4- Select the suitable scale for the entire assembly drawing.
5- Draw the main part and make sure that all parts are correctly assembled.
6- Prepare the title block
7- Label each component by leader and line and number it
8- Add overall dimensions necessary for workshop production
5.2
Task 2
For the below drawing, Fig. (5.1), draw a free hand sketch of the assembly guide
Fig. 5.1
WEEK 6
6.0
RULES AND FEATURES OF ASSEMBLY DRAWING
It is important that you follow some simple rules when producing an engineering
drawing which although may not be useful now, will be useful when working in
industry
6.1 Lay-Out of Drawing
All assembly drawings should follow a standard layout therefore interpreting and analysis
will be easier
Make your own Template follow the steps below
1- Open AutoCAD New File
2- Draw a frame according to your limits (use the size of paper you are using
often)
3- Add Title Block and Parts List table, add the information shown below
4- Now save your template using save as command, change the file type to
AutoCAD Drawing Template and then name your file ASSEMBLY
TEMPLATE
6.2 Parts list
Each part is given a unique number, indicated on the drawing by a circle with the number
in it and a leader line pointing to the part. The leader line terminates in an arrow if the
line touches the edge of the component..
A table of parts should be added to the drawing to identify each part, an example of a
parts list is shown below:
PART
NO.
PART NAME
NO.
OFF
MATERIAL
6.3 Dimensions
Detailed dimensions required for manufacture are excluded from assembly drawings. But
overall dimensions of the assembled object are usually indicated
6.4
Task 3
Fig (35) illustrates the details of V BLOCK ASSEMBLY, using scale 1:1 and first angle
of projection draw the following:
1- An assembled sectional Front View
2- Add Title block and parts list
3- Add 8 main dimensions
Fig 6
WEEK 7
7.0
ASSEMBLY DRAWING
7.1
Pin Joint Assembly
The drawing below (Fig. 7) shows the details of PIN JOINT ASSEMBLY, using scale
1:1 and first angle of projection draw the following:
4- Complete Sectional Front View with all parts correctly assembled
Fig. 7
WEEK 8
8.0
ASSEMBLY DRAWING
8.1
Screw Jack Assembly
The drawing below shows (Fig. 8) the details of SCREW JACK ASSEMBLY, using
scale 1:1 and first angle of projection draw the following
Fig.8
WEEK 9
9.0
ASSEMBLY DRAWING
9.1
Pulley Bracket Assembly
The drawing below shows (Fig. 9) the details of PULLEY BRACKET ASSEMBLY,
using scale 1:1 and first angle of projection draw the following
11- Use Design center library to obtain the required Hexagon Nut
Fig. 9
WEEK 10
10.1
Clamp Assembly
The drawing below (Fig. 10) shows the parts of CLAMP, using scale 1:1 and first angle
of projection draw the following:
15- Side View without hidden lines
16- Use Design center library to obtain the required Hexagon Nut
Fig. 10
WEEK 11
11.0 ENGINEERING DRAWING ANALYSIS
The goal of engineering drawing is to identify the contents and elements and understand
the details of the parts and objects drawn, in addition to any suggestions and
modifications to be added.
11.1
Solved Example (1)
The figure below (Fig. 11) shows the two views of a cylinder cover, study the drawing
carefully then answer the below questions.
Fig. 11
No
1
2
3
4
5
6
11.2
Questions
For what purpose this cover is used?
What is the pitch circle diameter of (p 10 mm,
8 holes?
What is the angle between any two adjacent
holes
What is the thickness of the cover?
What is the diameter of the dotted
lines.
Why are the holes located radially?
Answer
To close the cylinder
90 mm
45
10 mm ,8 mm
70 mm
Because the cover is circle
Solved Example (2)
The figure below (Fig. 11.1) shows details of a screw jack, study the drawing carefully
then answer the below questions.
Fig. 11.1
Question
Answer
M: Metric thread
16: Nominal diameter
2: thread pitch
1
What is meant by M 16 x 2
2
What is the maximum diameter of part No. (1)?
50 mm
3
What is the total length (X)?
87 mm
4
What does U/Cut 5 x 2 in the bolt view mean?
It means under-cut with 5 mm
width & 2 mm depth.
5
What is the shape of the material used inside?
Round bar Ø55 mm
7
It means chamfer operation 2 mm
length & 45° angle
boring, threading, counter
Name the internal machining operations. drilling ,bore,
counter-sink.
8
Name the external machining operations.
6
11.3
What is meant by 2 / 45 °
parallel turning, taper, u/cut,
threading, knurling.
QUIZ SHEET 3
1) The figure below Fig. (11.2) Shows the details of C-Clamp study the views
carefully and answers the questions below.
Fig. 11.2
Question
Answer
1
What is the maximum length of the clamped work
piece?
2
What is the section of part No. 1 at X-X?
3
What is the angle of projection of part No. 3 &
No. 4?
4
Why is the type of fit between part No. 1 & No. 4?
5
What is the purpose of hole q> 6 in part No. 2?
6
What is the material required for each part ?
7
Is the true shape of surface a shown on the
drawing? If your answers NO how can you get the
true shape?
The figure below Fig. (11.3) shows the details of a screw jack, study the views carefully
and answer the questions below
Fig. 11.3
Question
1
What is the purpose of the four grooves in the cup?
2
How can we clamp the screw to drilling hole Ø 12?
3
What is the minimum diameter of the handle that
turns the screw?
4
Why is there a gap of 3 mm at bottom of the base?
5
What is the total length of the Nut
WEEK 12
Answer
12.1
Guide Bracket with Inspection Plate
Figure 12
Figure 12, shows a pictorial view of a guide bracket, which incorporate inspection plate.
Draw full size and in correct orthographic projection the following views of the guide
bracket with the inspection plate fitted into its slot:
(a) An elevation in direction of arrow A
(b) A sectional elevation on plate PQ and in the direction of arrow B
(c) A plan in the direction of arrow C
Show in views (a) and (c) all hidden edges and includes on your drawing six
important dimensions.
Either first or third angle (but not both) methods of production may be used:
The method chosen must be stated on the drawing.
WEEK 13
13.1
Sliding Block Assembly
Figure 13
Orthographic views of a sliding block are shown in figure 13. Do not copy the views as
shown but draw the following views:
(a)
In place of elevation F a sectional elevation, the plane of the section and
the direction of required view being indicated at XX.
(b)
A complete outside end elevation in the direction of arrow E.
(c)
A complete outside plan in the direction of arrow P and in projection with
view (a).
Hidden part lines are not required on any of the views. Insert on the drawing
six dimensions, the title and the scale.
WEEK 14
14.1
Machine Vice Assembly
Figure 14
Figure 14 shows the details of small machine vice and a key to its assembly.
Draw, full size, in correct orthographic projection the following views of the completely
assembled vice, the sliding jaw being approximately 25mm from the fixed jaw.
(a)
A sectional elevation, in a vertical plane passing through the axis of the
square threaded screw, in the direction indicated by XX in the key.
(b)
A plan projected from the above.
Either first angle or third angle (but not both) methods of projection may be
used; the method chosen must be stated on the drawing.
WEEK 15
15.1
Bracket and Gland Assembly
Figure 15
Figure 15 shows the details of the parts of a bracket and gland assembly.
Details drawings of the parts of a bracket and gland assembly are given in Figure 15.
The studs are fitted into the holes A. The packing is then inserted into the 38mm diameter
hole at D, following the gland, which is fitted so that the 11mm diameter holes pass over
the projecting studs. The washers and nuts are then fitted to the studs and the nuts
tightened. Do not draw the given views but make the following views, full size, of the
assembly, in first angle projection:
(a)
A sectional elevation, the plane of section and the direction of the required
view being indicated at BB.
(b)
Half of a sectional elevation, the plane of section and the direction of the
required view being indicated at CC. Draw that half which appears on the left of
the vertical centerline
(c)
A half plan. Draw that half which appears above the horizontal center line,
in plan.

AUTOCAD 3 FILE - Unesco

Transcription

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