Create sheet metal bodies from complex geometry

Any solid geometry containing offset developable surfaces (linear in one direction) with a constant thickness can in theory be flat patterned. This refers to the types of solids that are created using the following techniques,

1. A linear sketch profile that is swept along a 3d spline curve where the spline curve has curvature in all 3 Cartesian directions.

2. Linear profile sweep along a linear path with "twist along path" applied.

3. Linear profile extrusion with applied twist and bending using the flex feature where the bend must be orthogonal to the twist direction.

These types of solids cannot be created as sheet metal bodies using the traditional sheet metal methods including both bottom up and top down approaches. Bottom up refers to creating the sheet metal parts by adding material and flanges on the fly, whereas top down is defined as creating the solid and converting this to a sheet metal body.

Each sheet metal feature used in both bottom up and top down approaches have specific requirements such as the need for planar faces or linear edges for certain selections. The “complex” solid geometry referred to in this blog does not contain such geometry or simply cannot be selected for the inputs into these sheet metal features.

This blog presents an approach using a combination of sheet metal, surfacing and solid features/ methods to obtain the end result of a Multibody sheet metal part.

The lofted bend feature can be used to create a sheet metal body with complex bending in one direction, it requires two 3d sketches containing 1 open contour in each 3d sketch. The two edges of the first Multibody segment may be converted into two 3d sketches using convert entities. An alternative and faster way to obtain this result is to use the face curves feature. Once the 3 lofted bend sheet metal solids have been created, a method for eliminating interference is presented, utilising the indent feature with the cut option toggled on. The lofted bend feature does not perfectly mimic the original geometry and therefore a method for removing unwanted portions of material using surfacing commands (zero offset and thickened cut) is demonstrated.