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section for var sec swp

S

surajcad

New member
hi everyone!


I have to use Pro-E 2001 for a particular valve casing design. I am using --var sec swp>nrm to traj, option. The trajectories are comming good but it wont accept a circle c/s through the begin points of 4 trajectories (1 origin and 3 other trajectories). If i place a spline c/s though the 4 points the curvature is steep and i am not getting the desired sections. I am not supposed to use surfaces offsetsand quilts for this particular applications since this is to be used for mould flow analysis.


could anyone help me please!
 
Please esecify which release you are using and explain your question with sketches and/or attachments. This way forum members will be in better position to help you.


Israr
 
Try using the "swept blend" feature. Sketch the trajectory and add "breaks" to create vertexes wherever you want a "cross section". After completing the sketch, specify where you want to add your cross sections. It defaults to putting cross sections at the ends of your sketch, (highlighted in red). Just pick on all points to add sections, amd select "done". Now sketch the cross sections, (or select curves), and your done.
 
the circle centre point should be on the master trajectory and the circle propile should passes thro' the other trajectory. try this it will work. if not post the photo copy of the trajectory u drawn.
Edited by: sathian83
 
hi friends,


thanks for the posts. I have tried your suggestions. my problem is, i cannot useSWEPT BLENDbecause only, origin section dimensions is given. I have completed the model using var sec swp>nrm to traj. But i am not able to give circle as the begin section. I have used orign traj as one of the traj on the circumference and norm traj at the centre. than 3 other traj at the quadrants of the circle section i want to give. but the circle does not snap with all the traj. It follows only one traj, ie origin traj. I tried using break point and curve conics. It is just not working. I am posting the prt file of the model I have done. The source projection scans are larger that 50k. so someone could give me a tip on how to post them. please go through the model and tell me how to snap a circular section on the trajectories.


thank you.


Suraj2006-01-19_091300_valve.prt.zip
 
If you can't use 4 distinct sections connected at eachtrajectory pointfor each quadrant than what you have is the best you can do. There's no way a circle will maintain its diameter along all points of your trajectories.
 
How about this section: two conics on the left and a 3 point spline on the right. If not you can try contraining the section with more trajectories. I think boundary surfaces can work also - you just need to solidify them which shouldn't be too much trouble.


View attachment 1679
 
Your problems, I believe, are simply limitations of the curves which might be understood by looking at how they are defined.

Arc (and circle):
Center and radius.
Two points on circumference and radius.
Three points on circumference.

Conics can not inflect, requires a degree three curve. (Had doubts about getting them to reverse, can be done if the tangents pass thru zero simultaneously. Learn sumpin new every day.)

--------

Sathya, edit your section, set selection filter to Constraint, select with crossing window and you will see two constraints highlight; center and radius. Three of the trajectories are doing nothing.
 
By "degree three curve" are you suggesting sketchinga spline? The more I look at it the more I think Style is the best way to model these features.
 
Uh huh. Technically (which makes it a stretch for me) the conic is also a spline representation (degree 2). The center Control Vertex is at the intersection of the tangent vectors and it's "weight" determines Rho (think I got that right, subject matter I have only a slippery grip on and I don't know for fact that Pro/E doesn't elevate to degree 3 internally). The degree 3 curve has (minimum) 2 in-span CV's, thus can inflect (not even sure if I'm using that term correctly).

Style might be good, don't have it, don't know. Maybe quicker in the long run?

I would (fwiw) probably model that differently. Hard to say how not knowing the exact drivers or intent. Regardless I'd probably break some of it up into more features and would probably rely on surface tools to some extent and merge the results into the solid. The cavity cuts I'd at least start by extruding a true diameter thru the flanges and go from there. I think I'd also try to work off the Geom Chks. Like I say, FWIW.

addendum: ... and would probably change my mind a time or two, once into the practical application of the details.
smiley9.gif
Don't mean to detract from efforts shown. It's a moderately trick shape.
Edited by: jeff4136
 
Thanks Jeff. Just wondering... I know the Rho is defined as A/(A+B) where C=D as noted in the image. Do you know any corresponding equation defining control vectors for a degree three curve that can be applied to sketcher modeling?





View attachment 1689
 
I didn't even know that.
smiley5.gif


I must say, to start, that I'm seriously (if I
had a brain I'd take it out and play with it)
challenged by mathematics and abstractions.
I believe tho', that the addition of a derivative
and lack of (?) an algebraic solution makes calcs
for a degree 3 curve much more involved, certainly
out of my league. Is there a specific application
or result you had in mind?

Consistent with my "take it (no, not That It
smiley1.gif
)
out and play with it" approach to such things I found
the following relationships (tangent vector intersect,
height, tangent to base offset, etc.) for a parabola
(rho = .5) interesting. I'll have to digest your
layout, think it answers some questions I hadn't been
able to fathom re conics other than the parabola.
Thanks for sharing it.

View attachment 1690

2006-01-20_165544_parabola_wf2.prt.zip
 
If you can post the Pro/E file - I'd be interested in taking a look at it. Are the boundaries conics?
 
How do you make the parabola extend past the line that goes throught the focal point. I have to extend the curve pass the focal point line.


texaspete
 
I'm sorry I should have been more specific, when "mgnt8" on Janurary 20 2006, posted the drawing of the parabola, This drawing help me alot. Now if I can extend the parabola curve pass the line which goes thought the focal point. I am designing a cavity for a rear Tail lamp for a car.


Thanks Texaspete
 
Hey, TexasPete. What parta Texas ya from?

Can you post something that illustrates or defines what you are trying to do? (What version Pro/E, if you haven't already said?)
Edited by: jeff4136
 
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