Wednesday, 11 December 2013

Surface Modeling Helmet Windshield

Cross Curve - Cross Breed


CrossCurve: Creates a 3-D curve at the intersection of two curves.
- Solid Edge Help.


What does that mean ?
Everyone knows, its always a point that is formed at the intersection of two curves.


So how exactly does a curve forms at the intersection of two other curves. Is it a cross-breed ?


CrossCurve is a powerful tool to draw a 3D curve.




t3101
 

What is a 3D Curve


There are four other distinct ways Solid Edge allows you to draw curves :

  • Sketching sketch   Lines, arcs, circles or curve in any reference plane. All curves drawn in a plane are 2D curves.
  • Keypoints Curve keycurve   Using this method it is possible to create both 2D and 3D curves.
    You need to key in x-, y- and z-coordinates of the points lying on the desired curve.
  • Curve by Table curvtabl   Same as keypoint curve and here too it is possible to create both 2D and 3D curves.
  • Contour Curve contucur   Draws a curve directly onto a surface. Depending on whether the surface is flat or curved, the curve drawn is 2D or a 3D.
    In short, a 3D curve does not lie in a single plane, but it travels in 3D space.
  • How is a Cross Curve Different


    Cross curve formation is different from the aforesaid four methods, in that, it uses existing curves to form a new curve.
    The other four methods of curve formation do it from scratch, either by keying in point coordinates or picking points with mouse.

    Significance of Cross Curve


    CrossCurve croscurv   is bending of flat curves, wherein a flat (2D) curve bends another 2D curve to form a 3D curve.
    The two curves should necessarily lie in two different planes, preferably mutually perpendicular planes.
    In other words, if you project a CrossCurve onto the reference planes, it will create its component curves.
    In the image on right, the red curve is the cross curve and the white curves are the component curves which create the cross curve.





    t3108

    Helmet Windshield


    A simple example is a transparent windshield of a helmet. This is a bent surface as shown.

     

    t3109

    The plane Surface


    The outline of the plane surface is a closed sketch.
    Drawn this sketch in a vertical plane i.e.. the curve is a 2D curve.

     

    t3110

    The Bending Curve


    The other curve that bends the closed curve is an arc.
    i.e.. the other (bender) curve is also a 2D curve.
    Draw the second curve in a plane perpendicular to that of the earlier curve.

     

    t3111

    Pick the Component the Curves


    Start the CrossCurve croscurv[4]   command on the surfacing toolbar.
    Pick the closed curve as the first curve   pickcur1
    Pick the arc as the second curve   pickcur2
    Click Finish and the cross curve is formed.


    t3113

    Bend the Curve


    Using CrossCurve croscurv[6]   the closed curve is effectively bent by the arc.


    Later a surface is fitted along the edges of the cross (bent) curve.

    The easiest way to do this is by using the Bounded Surface bondsurf


    Start this command from the surfacing toolbar and pick all the tiny bits of the cross curve.






    t3112

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