How to create elliptic paraboloid in Pro/E

Are you asking how to create a curve by equation or wanting the formula for a specific curve?

Insert / Model Datum / Curve / From Equation, define csys type, etc.

I don't know what the definition of an "elliptic parabaloid" is, but try pasting the following in as the equation definition after selecting Cartesian coord sys

height = 2 span = 5 x = (span/2) * cos(t*180) y = (4 * height / span^2) * x^2 Z = x^2/4 + y^2

and see what you get.

I think you need "t" in there somewhere, say, to get the "span" value from 0 to

1. But it's generally the engine for generating the curve by actually calculating and plotting a series of points that the curve passes through.

Jeff, thanks a lot for your answer. Here is how the Elliptic Paraboloid looks like

What I want to define is a surface not a curve. This surface is defined thru 2 variables in an equation in form of z = f(x, y) In MathCAD software I can easily do it. But I don't know how to do it in Pro/E

I think a simple solution would be to generate a parabola using an equation such as

x=4*t y=x^2 z=0

Then using that parabola to generate a revolved surface. I was able to generate a shape such as is shown on your link using that method.

Doug

Doug,Thank you for your input. However, there is basic difference between your geom and the one on the web. When cutting x-section parallel to XY plane, your geom gets circle while the web's geom gets ellipse.

The essence of the problem is whether Pro/E is not able to calculate 2 INDEPENDENT variables at the same time or not. In your equations above, you made y the dependent variable of x, but y should be independent variable. I dont't know how PTC customer service will comment on this. (Our maintenance just expired.)

Xiaoyu

It does appear that the intersection curve shown is truly elliptical, so I think this may be what you want (?).

Is this the same as a ellipsoid , where all curves are parabolic?

You know a pill shaped object..if so then use curves from equations in all planes I have all this worked out, but am short of time.. post over at mcadcentral if this is what you are looking for

this is cut in half otherwise it is full and does become a solid with no seam

full and radius edged hole solid

Thank you all for your help. cad/cam/guy, would you let us know how you create it or send file to my email snipped-for-privacy@gmail.com Thanks again

first I create 3 seperate curve to use for height,major,minor dim ... change the dims to names, so you can modify the shape without having to change the values in the equations then create some additional cys for the formulas.... you could just change the xyz values in the eqs. but I just made cys to allow pasting the equations;

/* --------------------xy_drive_curve -------------------- ratio=minor/major x=major*cos(t*360) y=major*sin(t*360)*ratio z=0 /*--------------------yz_sect_curve1 -------------------- ratio=major/ht x=ht*cos(t*180) y=ht*sin(t*180)*ratio z=0 /*---------------------yz_sect_curve2 ------------------ ratio=major/ht x=-ht*cos(t*180) y=-ht*sin(t*180)*ratio z=0 /*------------------- xz_sect_curve1 ------------------- ratio=minor/ht x=ht*cos(t*180) y=ht*sin(t*180)*ratio z=0 /*------------------ xz_sect_curve2 ------------------- ratio=minor/ht x=-ht*cos(t*180) y=-ht*sin(t*180)*ratio z=0

then surfrace by boundries.. with the xy curve being curve 1.. the others being 2nd direction... but in reality after thinking about this..it's not really a parabola... a parabola will not close up....it's close.. but not true.. anyway I am going to play with this doing some curve>intersection of some cones.. see where that leads

I think it depends on "how close gets the cigar", though I don't pretend to understand the shape (or what Mr X is after in the grand scheme).

The problem is going to be with conic definitions:

Degree two curves with three CV's (conic arcs)...

Ellipse: 0 < rho < 0.5 (for a quadrant it's always 0.414, increasing rho will push the point of max curvature away from quadrant point)

Parabola: rho = 0.5 (always, tangent angles define the "portion" of curve defined)

Hyperbola: 0.5 < rho < 1

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*If* what I did with the VSS is close to what's desired and a closed shape such as the ellipsoid is desired I think I'd planar trim the shape, mirror it, and do a G2 boundary blend between the two. The "long axis normal" xsec will be an ellipse. The position of the trim plane will define the max girth. A little layout geometry could be used to define the trim for any given max girth.

Interesting stuff ...

(Speaking of which: CCG, if I haven't confused aliases; I did get your message a while back. SHTF about that time and I forgot about it. If you are interested in an example of the cylindrical cam groove, holler and I can email it.)

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