1. Field of the Invention
This invention relates, in general, to technology for designing fold lines in sheet material and more particularly to a method, a computer program product and a method for designing fold lines in sheet material.
2. Description of Related Art
A commonly encountered problem in connection with bending sheet material is that the locations of the bends are difficult to control because of bending tolerance variations and the accumulation of tolerance errors. For example, in the formation of the housings for electronic equipment, sheet metal is bent along a first bend line within certain tolerances. The second bend, however, often is positioned based upon the first bend, and accordingly, the tolerance errors can accumulate. Since there can be three or more bends which are involved to create the chassis or enclosure for the electronic components, the effect of cumulative tolerance errors in bending can be significant. Moreover, the tolerances that are achievable will vary widely depending on the bending equipment, and its tooling, as well as the skill of the operator. The problem of controlling the positioning of bend lines, of course, can occur in connection with may other three-dimensional products.
One approach to this problem has been to try to control the location of bends in sheet material through the use of slitting or grooving. Slits and grooves can be formed in sheet stock very precisely, for example, by the use of computer numerically controlled (CNC) devices which control a slit or groove forming apparatus, such as a laser, a water-jet cutting apparatus, a punch press, a knife or other tool. Such slits and grooves have been used in prior systems as a basis for bending sheet material. For example, U.S. Pat. No. 6,640,605 to Gitlin et al. describes a method of bending sheet metal to form three-dimensional structures. The bend forming techniques of such prior slitting-based systems may, however, significantly weaken the resulting structure.
Industrial Origami, Inc. (IOI), the assignee of the present invention, is presently developing new and improved approaches to overcome the disadvantages of prior sheet material bending systems. Namely, by providing sheet materials with new and improved slit configurations, IOI has developed an approach that allows bending of the sheet material along a fold line that results in a three-dimensional structure having edge-to-face engagement along the fold line. Such edge-to-face engagement greatly increases the strength of the resultant three-dimensional product compared with prior art slitting methods. Additionally, IOI's new slit-based bending designs result in structures that may be more rigid than traditionally bent structures that are un-slit. Furthermore, IOI's new and improved slit designs advantageously reduce stress concentrations in the three-dimensional structure along the fold lines.
While it is possible to draw IOI's new and improved slit configurations with the standard sketch tools of conventional computer-aided design (CAD) systems, a CAD user may find that drawing, locating, scaling and shaping individual compound-shaped slits that constitute IOI's slit configurations rather repetitive and challenging. What is needed is a method, computer program product and system that is able to readily allow a CAD designer to determine an improved fold geometry based on IOI's new and improved slit configurations and efficiently apply such fold geometry to a sheet material design.