Modeling sheet metal intersection in Autodesk Inventor

The intersection of two sheet metal bodies will often challenge the best Inventor user. Your company may build complex material handling duct work or storage bins that often will have another sheet metal body intersecting at odd angles on curved surfaces. A simple example of this is shown below.

You have to develop the sheet metal flat pattern for both the branch duct and the run duct. Inventor makes this task very easy. If you have worked with Inventor surface modeling and sheet metal methods, you have to tools to do the job. The issue that must be avoided is a flat pattern with taper edges. There are not may lasers or water jets cutters in industrial use that can cut the flat pattern with taper edges.

The first step is to model both run and branch ducts each as single surfaces. Normally you will model these using final outside dimensions. You must make sure they fully intersect.

I will be developing the finished branch duct in this article but a similar workflow can be used to create the run duct. Using the Inventor “Trim Surface” tool, remove the end of the branch duct protruding inside the run duct.

Next you need to use the Inventor “Thicken/Offset” command to add the desired sheet meal thickness to the inside of the branch duct surface. In my example, I am using 0.075″ (14 GA Mild Steel). Please note that I have made the surface model invisible in the second screen shot.

The next step is to set the sheet metal default to match the thickness used in the Thicken/Offset command. It this value is not exact, the creation of a flat pattern will fail. The next step is to use the Inventor sheet metal “Rip” command to add a gap to the duct.

Finally, select the side of the duct you desire to be on the outside of the flat pattern, and pick the “Create Flat Pattern” tool.

Sure does beat using a calculator and drawing board!

For more of Mark’s Inventor tips and tricks, check out IMAGINiT Manufacturing Solutions Blog.

Mark Flayler is a senior application engineer with IMAGINiT Technologies, specializing in manufacturing environments. He is also PSE and ATC certified in AutoCAD, AutoCAD Mechanical, AutoCAD Electrical, Autodesk Data Management and Autodesk Inventor.