Displaying Characteristic Curves

Characteristic curves are displayed in the folded and/or unfolded view of the part. They can be selected, though not edited, and used as a support (to create points for example).

Characteristic curves can be computed for surfacic flanges or stamping features with a fillet. They can be also computed for swept flanges.

Available Characteristic Curves

The following characteristic curves can be computed on both folded and unfolded view, except when otherwise specified:

• BTL: Bend Tangent Line
  Limits of the fillet.
• IML: Inner Mold Line
  Intersection between internal surfaces of the base feature and the flange (both extrapolated in tangency if necessary), without the bend.
• OML: Outer Mold Line
  Intersection between external surfaces of the base feature and the flange (both extrapolated in tangency if necessary), without the bend.

• Second OML: Second Outer Mold Line
  Corresponds to a parallel curve to the BTL support in the direction of the base feature SB distance value. It is only available in the unfolded view.
  
  Illustration of Set back or SB: (Radius+Thickness)*tan(Alpha/2). Alpha is a constant for swept flanges, so SB does not depend on the plane where it is computed:
  
  
  
  Illustration of the IML, OML and Second OML curves:
  
  
• CLB: Center Line of Bend
  Positioned midway between the BTLs. It is available in the flat view.

Features which Support Characteristic Curves

Characteristic curves can be computed for the following features:

• Surfacic Flange/ Swept Flange (both brake-formed and hydro-pressed):
  • BTL on the base feature
  • BTL on the support
  • IML
  • OML
  • Second OML (unfolded view only)
  • CLB

• Stamps with an internal cutout (flanged hole and flanged cutout):
  • BTL on the base feature
  • IML
  • OML
• Stamps without an internal cutout (bead, curve stamp, user-stamp, other stamping types, etc):
  • BTL on the base feature

Open the CharacteristicCurves1.CATPart document. This sample includes two surfacic flanges, a bead and a flanged hole. All characteristic curves are put in show in the following images.

Characteristic Curves Computed on the Folded View

Characteristic Curves Computed on the Unfolded View

More about Characteristic Curves

Standard Management of Characteristic Curves

Administrators can now customize characteristic curves through standards:

• Graphic properties (color, line type, thickness) apply to both 3D views (in the Aerospace SheetMetal Design workbench) and 2D views (in the Generative Drafting workbench).
• Visibility specifies whether characteristic curves should be generated in 2D views.

Refer to the Administration Tasks section for more information on this subject.

Characteristic Curves and Settings

As a user, you can manage the visibility of characteristic curves in folded and unfolded 3D views through settings. Refer to Display in the Customizing section for more information.

When you need to update a feature created before V5 R18 or create a feature generating a CBL curve on a part created before V5 R18, a warning message appears indicating that the graphic properties of the CLB in 3D and in 2D are attributed by default and cannot be changed. The CLB is represented as follows:

Characteristic Curves in Hybrid Design Context

In hybrid design context, if you define a feature as a working object in the specification tree, the characteristic curves of features created after the Define In Work Object are not displayed anymore on the geometry.

Surfacic Flange.1 defined as a Working object on a hybrid part

Surfacic Flange.1 defined as a Working object on a non-hybrid part