Large Cover Mold Surface Reconstruction And Applied Research, In The Stamping Process

A set of discrete data sampled from an object is given in advance during the research on large-scale metal pressing and forming. The object's CAD model based on these data must be faithfully reconstructed in order to calculate the length of all pressing-poles, and that is one of the most crucial steps for the CAM in practice.The study on surface reconstruction has been reached a very high level. Being a physical process, metal pressing and forming is an elastic deformation which result from effect of a force on a sheet of metal. Taking that fact into account, this paper will fit the model's surface in a parametric bicubic spline surface. However, some model's surface with flatter shape(differentiated by a given tolerance) will be fitted in hyperbolic paraboloid so that the length of pressing-poles can be immediately calculated and programmed.The purpose of model's surface reconstruction is to calculate the length of pressing-poles and to program for CAM. Because the differential operation on a parametric free-form surface's model has been remaining a hurdle, a special technique for the surface subdivision is given. According to the given tolerance, the surface is subdivided into many small patches and these .patches will be fitted in hyperbolic paraboloids. Being farther operated, these hyperbolic paraboloids will be fitted in the mid-planes of these hyperbolic paraboloids. The mid-planes are used to calculate the length of the pressing-poles and make the calculation simple.For the sake of application to metal pressing and forming in practice, the programming in C++ has been completed and debugged successfully.With respect to computer-aided manufacturing of the large-scale cover of an automobile, it is proved that the technique given in this paper is an effective measure which can meet a need in practice.