Research On The 3D Sheet Metal Flattening And Process Planning

Sheet metal parts is widely used in some industrial production field, such as automobile,aviation,chemical manufacture and so on. With the development of design and manufacturing level, more and more products related to sheet metal parts, especially the parts with undevelopable surface, which brings difficulty in pattern calculation. Meanwhile, under the promotion of information technology and digital manufacturing trends, sheet metal computer aided process planning (CAPP) is one of the useful ways to shorten the production cycle, improve the working efficiency and enhance the competitiveness of enterprise. As a result, research on the key technologies, approximate development of sheet metal undevelopable surface and sheet metal CAPP, has important significance and value in engineering.In this paper, algorithms based on vertices and energy model are adopted to flatten the sheet metal surface respectively. Firstly, the surface is discretized into many triangles in 3D environment, the data of discrete vertices is got, then according to the different mapping ruler and deformation ways, triangles is mapped to 2D plane, the surface flattening is completed. For the vertices algorithm, take the discrete point as the object, analyze and calculate the change values of all angles which include the discrete point after flattening, the values of angles after flattening can be work out, and the pattern can be got. This algorithm is simple and fast operation, it is suited to some simple parts and parts with little bending degree. For the algorithm based on energy model, basic triangle is selected, then the surrounding triangles are found and mapped to 2D plane in unconstrained and constrained flattening ways. In the flattening process, discrete boundaries are assumed to be elastic bars along the surface, energy model is used to search the minimum deformation energy of triangle, the optimized flattening result can be got. This algorithm is complex but very useful, it is suited to developable surface and complex surface. Some examples are given to certify and analyze these two algorithms.Features and difficulties of sheet metal traditional process planning are also analyzed in this paper. On this basis, sheet metal CAPP system is designed, which has many functions such as process design,database management,enterprise resource management,and files output.In the end. by constructing the 3D environment, the sheet metal design and process system is realized. The system has the advantages of simple operation and strong practicability.