Sheet metal design is an integral part of the design commands of TopSolid. These commands will enable you to design sheets and to carry out their unbending in compliance with the unbending rules.

These are divided into three major categories:

• Creation commands: from the sketch (Sheet metal on sketch), from shapes (Sheet metal by thickening) or from documents from other CADCAM software (Sheet metal recognition).

• Modification commands: Flange, Bends upon edge, Bend along a line, Angle relief, Edge relief, Standard layout and Change faces side

• Unbending commands: Unfolding rules...

The unbending is then done in a unfolding document which also contains the part to unbend.

What is an unfolding surface?:

A lot of definitions are available, but intuitively, each surface which can be created with a lofted surface between 2 curves or between a curve and a point can be considered as unfoldable for an unfolding operation.

Examples of unfolding surfaces:

- Cylinders

- Cones

- Extruded surfaces

- Inclined cylinders

- Inclined cones

- Inclined pipes

- Helix

These surfaces are characterized by the presence of linear section curves in one or two of their main directions.

Strictly speaking, a surface is unfoldable if, along one of each section curve, all normals to the surface are parallels. In the opposite case, the surface is said "quasi developpable". TopSolid allows to unfold this kind of surfaces, but they are modified by adding an additional deformation, so they are not strictly "rollable".

With transition part, we are sometimes forced to use this kind of surfaces, if the additional deformation is low. In this case, we add some intermediate folding lines to allow the manufacturing by crunch faces.