********** README FILE FOR THE MACRO, 'FLAT_PATTERN' ************
Written by Darren C. Haverstick
Paul Mueller Company Springfield, MO
Phone: 800-683-5537 Ext 725 Email: dhaverst@mail.orion.org
This macro creates flat patterns that result from the intersection
of a fitting of some particular cross-section and a cylindrical shell. It
also will create a pattern for a repad to go around the fitting at the
point of intersection. A repad is simply a band of material welded onto
the shell to reinforce the fitting/shell intersection.
My company makes a variety of products out of plate and coil steel.
Often times, we have a fitting intersecting a cylindrical shell and we
need to precisely cut the hole in the shell that the fitting will go
into. We do this by making a flat pattern of the 3D surface of
intersection, place it on the shell, and cut around it. We also make a
pattern to wrap around the outside of the fitting so it can be cut to
accurately fit the shell. While creating these flat patterns might be
easy in a 3D graphics package, doing it in ME10 is tricky. This macro
uses rotational matrices and a descriptive geometry technique to get the
job done.
You are given a choice of five cross-section types for your
fittings: 1) Circular 2) Elliptical 3) Oval 4) Rectangular with Square
Corners 5) Rectangular with Rounded Corners. By answering a series of
questions, you will tell the macro how your fitting is positioned in
3-dimensional space with respect to cylindrical shell. Several graphics
are generated to clarify the questions and aid you in answering them.
Once all the questions are answered, the macro calculates points along
the perimeter of the cross-section you chose and places them in 3D space.
These perimeter points are then projected through the cylindrical shell
and the points of intersection a determined. The points of intersection
define the boundary of the 3-dimensional surface of intersection. Using a
descriptive geometry technique found in any drafing book, the macro takes
the 3D points, determines the relationships between them, and 'flattens'
them out in to 2D space. The result is a flat pattern of the surface of
intersection.
The macro can take this process a step further by using the same 3D
boundary points to create a pattern to wrap around the fitting itself.
The fitting can then be cut by this pattern so that it fits snugly
against the shell.