Generating smooth parting lines for mold design for meshes

ABSTRACT

This paper considers the mold design problem of computing a parting line for a complex mesh model, given a parting direction. Existing parting line algorithms are unsuitable for this case, as local variations in the orientations of the facets of such models lead to a parting line which zig-zags across the surface in an undesirable way. This paper presents a method to compute a smooth parting line which runs through a triangle band composed of triangles whose normals are approximately perpendicular to the parting direction. The skeleton of the triangle band is used to generate a structure representing distinct topological cycles, and to decompose the triangle band into singly-connected surface pieces, giving candidate paths. We choose a set of paths giving a good cycle; the final smooth parting line is then constructed by iteratively improving the quality of this cycle. Compliance in the physical material, or minor modifications to the surface itself, will ensure that such a parting line is appropriate for use.

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INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.5 Computational Geometry and Object Modeling
          Subjects: Geometric algorithms, languages, and systems

Additional Classification:
  J. Computer Applications
  J.6 COMPUTER-AIDED ENGINEERING
      Subjects: Computer-aided design (CAD)

Keywords:
mesh, mold design, parting line