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Trade 05: Mechanical Engineering Drawing and Design CADD
Post-
Secondary/Secondary Ontario - 2011
This competition consists of two sessions both sessions must be
attempted toreceive a final grade.
Part 1: (3.0 Hours - 55% of total mark)
READ ALL THE QUESTION BEFORE YOU START
These questions are derived from a project proposal for the
Montreal, 2001 World Skillscompetition from the German delegation.
The part is known in Germany as a Maltese Cross, butin North
America we commonly know it as a Geneva Wheel. Its function is to
index an output
shaft a specific amount for every revolution of an input shaft.
In this instance the output shaft(part #3) increments 60o for every
revolution of the input shaft (part #4).
Required:
Part A Morning Session (40% of total mark)
Two parts are to be drawn as details part #4 (Input Shaft) and
part #7 (Maltese Cross). Both ofthese parts are to be extracted
from the given assembly. You may choose to redraw or use thegiven
drawing from which to create the parts its up to you. The finished
drawings requireCOMPLETE dimensioning, including ISO standard
tolerances, geometric dimensions andsurface finishes. You are to
determine the appropriate values based on your understanding of
the parts application.
Complete the title block supplied on the disk with your
competition number only no names orschools please. Save the file on
the disk as DETAILS_YOUR NUMBER GOES HERE.
Part B Challenge Question - Kinematics (15% of total mark)
As previously mentioned, this particular Geneva wheel indexes
1/6th of a turn for everyrevolution of the Input Shaft. Your last
task for the morning session is to design a Geneva wheelthat
increments 1/8th of a turn for every one revolution of the Input
Shaft. Using the originaldimensions for part #7 replace the 6, 14mm
slots with 8slots of the same size - draw the
changes that would have to be made to part #4 to enable the
wheel to work. This will meanchanges to the center distance between
part #4 and part #7, modifications to the distance fromthe center
of the input shaft (part #4) to the center of the driving pin (part
#18), and changes tothe clearance arcs on part numbers 4 and 7. A
hint: study the front view of the given assembly look for a
geometric relationship. There are calculations involved to
determine the requiredanswers. Place the edited drawings on the
same sheet as Part #1 these should be in a single
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assembled view and dimensioned as outlined above no other
details/parts ordimensioning/tolerancing is required for this
edited version. Partial marks will be given forattempts at this
question.
Given:
A 1:1 paper copy of the assembly shown in THIRD ANGLE
PROJECTION.Copies of the assembly in dwg and dxf formats on the
supplied disks.Data sheets that may aid you in determining values
for dimensioningAppropriate title block in .dwg and .dxf
formats
General:
You are to use your own discretion in determining features that
may not be clear to you. If thereare missing dimensions on the
hardcopy you may use the 2D drawing to determine them as thepart
has been created at a 1:1 scale. The judges WILL NOT answer any
questions pertaining tothe challenge. Software, calculators and
reference manuals are allowed. Maintain the C.S.Astandards for all
your drawings.
You must submit the drawing file on the disk provided. Use your
number to identify the drawingfile. Do NOT exit the drawing file or
switch off the machine, judges may wish to mark or viewaspects of
the design on the screen.
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Afternoon Session (2.5 Hours 45% of total mark)
READ entire question FIRST it will affect how you build the
model!
Part A: (36 Marks)
Create a PARAMETRIC SOLID MODEL of part #1 - Housing (30). Plot
a single isometric viewon a single sheet at full size that will
best describe the part. NO OTHER VIEWS SHOULD BEON THIS SHEET (3).
Assigning Aluminum as the parts material, determine the Volume (mm
3)and the Weight of the part (Kg) (3). Print/Insert this
information on the same sheet as theisometric view. Save this part
as Housing_Your Number goes here. Insert a title block andplace
your competitor number in an appropriate location - you will find a
suitable title block onthe disk as a .dwg or a .dxf file or you can
create a simple block yourself.
Part B: (9 Marks)
Due to a change in the design (the edited Geneva wheel) the
housing needs to have thefollowing changes made to it:
Change the position of the Input Shaft bore location relative to
the Output shaft bore locationfrom 86.6mm to 81.18mm (this is the
answer to the morning question!), the entire outer bodyshould
change position as well to maintain concentricity between the input
shaft bore and therelated housing features. Save this edited
drawing as Housing_Edited_your number goes here(5). Plot TWO
isometric drawings on the same sheet one looking from the front
area and onelooking from the back this will enable the judges to
see the effect of your edits on both sides ofthe part. (4) Insert a
title block and place your competitor number in an appropriate
location -you will find a suitable title block on the disk as a
.dwg or a .dxf file or you can create a simpleblock yourself.
General:
You are to use your own discretion in determining features that
may not be clear to you. If thereare missing dimensions on the
hardcopy you may use the 2D drawing to determine them as thepart
has been created at a 1:1 scale. The judges WILL NOT answer any
questions pertaining tothe challenge. Software, calculators and
reference manuals are allowed.You must submit the drawing file on
the disk provided. Use your number to identify the drawingfile. Do
NOT exit the drawing file or switch off the machine, judges may
wish to mark or viewaspects of the design on your machine.
