Baixe ProEngineer Tutorial: Creating Revolved and Swept Features, Patterns, and Fill Patterns e outras Notas de estudo em PDF para Engenharia Mecânica, somente na Docsity!
Intermediate Modeling
By D Cheshire Not all shapes are made from extrusions so this second tutorial introducessome new types of features. These include revolved features where acurve is spun around a central axis (like working on a lathe or potterswheel) and simple sweeps where a cross-section curve is swept along acentre line (ideal for making pipes). We will also return to the subject ofpatterns and rounds showing some more options for these commands.The subject of this modeling exercise is a pair of headphones. Once againthis will be a representation model made as
a single part.
In reality
headphones are made from many pieces assembled together and this isthe way you should use ProEngineer if you were going to manufacture theheadphones. As a designer looking at the overall finished product it isoften
easier
to^
model
the
complete
design
until
a^ final
decision
to
manufacture is made then return to break the design down into individualdetailed parts later.
Figure 1 : The Finished Headphones
Revolved Features Now you understand the basic principles of using ProEngineer such asusing the dashboard, defining sketch planes and sketching we will notcover these in detail unless something new is needed.Start
ProEngineer,
Create
a^
new
part
called
headphones
using
the
mmns_part_solid option. Choose the command INSERT > REVOLVE andnotice the revolve feature dashboard appears.
Figure 2 : The Revolve Dashboard
Just like extrusions revolved features use sketches that are created in thesame manner. Enter sketcher (PLACEMENT > DEFINE) choosing FRONTas the sketching plane. Draw the two lines and the arc shown in Figure 3a.If you try to exit sketcher now you will get an error message – No axis ofrevolution. All revolved features must have and axis of revolution – acentre line around which the curve is revolved. This is drawn using theCentreline tool
found by clicking the small arrow next to the normal
line tool
. Select this tool now and draw a centreline on top of the
horizontal line you have already drawn – it should lock onto the referenceline.
Figure 3 : Revolve Sketch and Feature
Exit sketcher. The default option for revolve is to revolve the sketch for afull 360 degrees (see dashboard) which is exactly what we want so justclick on the green tick to finish.The next step is a simple extrusion for which you should not need muchhelp but it gives a chance for us to discuss the options for length ofextrusion.
Intermediate Modeling
By D Cheshire
Figure 4 : Thru Options
Sketch on to the FRONT datum plane and extrude both sides
by a
distance of 50.
Figure 5 : Double Sided Extrusion
Sweep Features Now we need to make a wire to attach the phones to the head strap.There is an easy feature for this called a sweep. This requires two curvesthe centreline of the ‘wire’ known as the trajectory and the second is thecross section of the wire which in this case will be a simple circle – thoughit can be any shape you want.
We need a new datum plane to draw this trajectory curve on. ChooseINSERT > MODEL DATUM > PLANE then click on the RIGHT datumplane then whilst holding the CTRL key click on the axis through the centreof the last extrusion. The Datum plane dialog should now contain tworeferences and next to the RIGHT datum reference it will say Offset - clickon this and choose parallel.
Figure 6 : A New Datum Plane
Now we can draw the trajectory curve for the sweep feature. ChooseINSERT > MODEL DATUM > SKETCH and choose DTM1 (the datumplane just created) as the sketch plane. Draw the sketch shown in Figure8. Notice the two extra vertical references created on the ends of theextrusion. The easiest way of drawing this sketch is to first draw 5 straightlines then add fillets
at each corner.
Sketcher has some intelligence built into it in the form of geometric rules orconstraints. You may have noticed this intelligence in operation – forexample lines drawn near vertical or horizontal have the letters V or H nextto them and lines drawn with similar length are given a reference like L1.These constraints are either automatically assigned by sketcher as youdraw or you can manually tell ProEngineer to add constraints by using thesketcher constraint icon
. See Figure 7 for an explanation of all of the
constraints available to you.
BLIND –
you type in a value as the depth of the extrusion. SYMETRIC –
the^
extrusion goes
both sides of the sketch plane. THRU NEXT – the extrusion stopsat the next surface. THRU ALL –
the^
extrusion goes
through all geometry in the part. THRU SELECTED –
the extrusion
THRU UNTIL – the extrusion goesto selected surface or plane. goes to a plane thru selected point,curve, surface or plane.
Intermediate Modeling
By D Cheshire and draw a 10 circle centered on the automatic references. Exit sketcherand end the feature definition.
Figure 11 : The Ear Muff
A final chance to practice sweeps - for this tutorial at least. We will makethe head strap to show you don’t have to use circular cross sections. Wewill need to draw the curve for this sweep so choose INSERT > MODELDATUM > SKETCH and choose FRONT as the sketch plane. Draw thesketch shown in Figure 12. Remember that additional constraints can beadded using the
icons. Add a vertical constraint between the top end of
the arc and the centre of the arc using the
icon. Now this is quite
tricky till you get the hang of it! - the left hand end of the arc is aligned withcentre of the wire by using the
icon and repeatedly RIGHT clicking
near the centre of the wire until the END:CURVE symbol
highlights.
Exit sketcher.
Figure 12 : Head Strap Trajectory Curve
Now to add the 3D geometry. Choose INSERT > VARIABLE SECTIONSWEEP then click on the first icon
to make a solid. Now, in the main
graphics window click on the curve you have just drawn. Enter sketchmode
and draw the oval in Figure 13 centered on the automatic references. Exit sketcher and end the feature definition.
Figure 13 : Head Strap
To tidy up the strap add a double sided extrusion of a diameter 6 circlethat is 35 long around the join of the strap to the wire.
Figure 14 : Extrusion
More Patterns In the introductory modelling tutorial you were introduced to patterns –multiple copies of features. Those simple patterns were rectangular orlinear patterns. Here we will introduce polar patterns (based on angles)and rather clever Fill patterns unique to ProEngineer.
Intermediate Modeling
By D Cheshire
Fill Patterns Fill patterns are very easy and impressive! Like all patterns you first haveto create something to pattern. So let’s make a cut into the earpiece for thesound to get out. Make a 1 diameter extruded cut 0.5 deep at the centre ofthe flat face of the earpiece.
Figure 15 : Initial Cut for the Pattern
Now to make multiple copies of this cut. Right click on the cut you havejust made in the model tree then choose EDIT > PATTERN. The defaulttype of pattern is to define by Dimensions as shown by the first list box.Change this first list box to the Fill option and the appearance of thedashboard should change to that shown in Figure 16.
Figure 16 : The Fill Pattern Dashboard
This type of pattern fits as many copies of the feature inside a boundary asit^ can.
So
the
first
step
is^
to^ draw
the
boundary.
Click
on
the
REFERENCES > DEFINE and select the flat face of the earpiece as thesketch plane. Draw a 35 circle. This circle will form the outer limit of thecopies – all copies will fit inside this circle.Exit sketcher and you will all ready see to black dots representing thecopies which will be made. They are in the shape of a square as shown bythe 3
rd^ list box. Change this to Diamond and see the difference and change the 4
th^ list box – the spacing – to 5. Note that with this type of
pattern you can also click on any of the black dots (they turn white) to
leave that copy out of the pattern. Close the Dashboard with the greentick.
Figure 17 : Fill Boundary and Diamond Pattern
Polar Patterns The fill pattern is very versatile and can be used in many situations but youshould be aware of other ways of making patterns. So here are someexamples of patterns based on angles – polar patterns.First we will make a cut into the back of the phone. Choose INSERT >EXTRUDE and enter sketch mode choosing DTM1 as the sketch plane.The sketch you need to draw is shown in Figure 18.
Figure 18 : Polar Pattern Sketch
Exit sketcher. Make sure the option for removing material through the backof the phone is set before closing the dashboard. Now add a round featurearound the edge of this cut to make the appearance better.
Intermediate Modeling
By D Cheshire To complete simply RIGHT click on the cut in the browser on the left andchoose PATTERN. Choose the AXIS option and pick the axis you createdearlier, choose 5 cuts and type an increment of 22.5 (use
to make
sure the pattern goes the right way). Close the Dashboard. Elliptical Rounds Use your previous experience to add a round to each edge of the first ofthe holes you have just created. Remember to hold the CTRL key to selectthe two edges (top and bottom of the hole). Before exiting the rounddashboard click on the Sets menu and you will see the dialog in Figure 23.
Figure 23 : Round Sets
This dialog allows you to vary the type of round. Change the word Circularto the option D1 x D2 Conic and you will get two radius values in thedashboard to define a conic round. Change these values to 2 and 1respectively – look on the model to check you get them the right wayround so that the large radius is on the outside of the strap.Right click on the latest round feature then choose EDIT > PATTERN. Thefillet is automatically propagated around each of the cuts because theoriginal cut to which this round ‘belonged’ was itself patterned! Mirroring Finally to create the other half of the headphones click on the nameHEADPHONES.PRT at the top of the browser window then choose EDIT >
MIRROR pick the flat end of the head strap as the mirror plane. Theheadphones should be complete! Review So what should you have learnt?
•^
How to create revolutions to add and remove material.
-^
How to use more complex sketch functions.
-^
How to create fill patterns.
-^
How to create polar patterns.
-^
How to create elliptical rounds.
-^
How to mirror the whole model. Any problems with these? Then you should go back through the tutorial –perhaps several times – until you can complete it without any help.
