Research On Methods & Several Key Techniques Of Parametric Simulation Design For Panel Stamping Die_Face

With rapid development of China's automobile industry and customer differentiation of individual desire to consume, higher requirements have been raised for the design and manufacturing capabilities of mold companies. In order to shorten the development cycle and reduce mold development costs, sheet metal forming CAE software Play a decisive role in mold developing. Designed mold was imported CAE simulation software by panel mold designer, simulations was carried out after parameters set correctly, then the simulation results was used as reference for judging pros & cons of mold and modifying design. Simulation mold of panel was generated by adding the mold surface and addendum based on part's geometry datum, so the surface design is One of the key to mold design.Die face design of the traditional mold is achieved in CAD software, but in order to verify the correctness of die face design, the simulation results of CAE software was standard for verifying and modifying. The basic flow is divided into five steps. First, die face design of mold is achieved in CAD software. Second, the mold is exported from CAD software. Third, the mold was imported into CAE software. Fourth, Sheet metal stamping simulation is done in CAE software. Fifth, the result of simulation is analyzed. If die face design has defect that Indicating by simulation results, the simulation flow would be re completed until the satisfactory design results was achieved. The geometrical model datum which was imported or exported between CAD software and CAE software are Easy to lose datum, meanwhile operation for the datum transmission is cumbersome. Die face digital design theory was proposed based on CAE in order to overcome shortcomings of traditional die face design. The core idea of the theory is the Parametric Design for die face in CAE system. The basic flow is divided into three steps. First, die face design of mold is achieved in CAE system. Second, Sheet metal stamping simulation is done in CAE software. Third, the result of simulation is analyzed. Die face design would be changed without CAD software within the system if die face design has defects. The stamping simulation of mold which has been changed is done again until a reasonable design of die face was got. Advantages of die face digital design based on CAE mainly includes two aspects , on the one hand, Drawback of datum loss was overcome when datum was imported or exported between CAD software and CAE software, on the other hand, the efficiency of mold development can be enhance greatly.The research on die face digital design supported by the National Automotive Electronics major projects of high tech industry "CAD/CAE/CAM software platform for digital auto body parts fine design and manufacturing"(SDRC No:2040), the Ministry of Science and Innovation Fund "Stamping forming simulation technology applications", the Key Project of the National Natural Science Foundation of China(No.19832020) ,the National Outstanding Youth Science Fund "The CAD expert system theory based KBE of stamping design and the research on the polymer forming theory and calculation method "(10125208) and the Project 985 Automotive Engineering of Jilin University. The related theories and key technologies of panel die face digital design were studied thoroughly based on CAE system. This paper has researched on the following several key technical issues:Module of KMAS/Die Surface digital design for auto body panels based on Spatial's ACIS platform, and it includes the following function: unfold flange, hide flange, inner fill, outer smooth, symmetry, turn normal, tipping, binder surface, addendum surface. The extension name which is opened in Text file of ACIS platform is .SAT, geometry and topology of model is described by Boundary representation. In order to expand the application scope of platform, it is necessary that KMAS/Die Surface can identify file generation in other CAD software. Data Interface was designed in this paper based on standard neutral file IGES, the datum is shared in both KMAS/Die Surface and other CAD software by the data interface.Preprocessing operation would be done before KMAS/Die Surface design based on Part geometry, the key operations are hide Flange and inner fill. Usually, hide flange is a manual operation. Manual operation would be very time consuming and laborious when there are many tiny pieces of part need to hide. In regulations, Mesh surface need to hide if the angle is greater than 91°between normal of mesh surface and initial tipping. Surface need to hide if hidden mesh threshold(K) of a surface is greater than 2. Self developed hidden flange algorithm can identify surfaces which need to be hidden automatically and accurately and hide the surface. Particularly, the surface is not removed from the structure but not displayed on the topology during hidden operation.Inner fill operation of foreign CAE software is divided into five steps. First, the type of fill hole is confirmed, e.g. round holes, square holes, internal holes, border holes. Second, the holes would be filled is selected. Third, fill in holes. The Inner fill operation have some defects, on the one hand, operation is cumbersome, on the other hand, there is boundary line between inner fill surface and part surface. The existence of the boundary line is not conducive to the overall part surface for meshing. Algorithms of automatic fill holes is proposed, all holes are confirmed by comparing the size of the border bounding box, then a bi cubic Coons surface is generated as fill hole surface by inner hole boundary. In order to achieve the purpose that parts mesh is generated as a whole, fill hole surface and part surface need to healing.Automatic outer smooth is the most important function in Die Surface digital design. This paper presents an automatic outer smooth algorithm, algorithm flow is as follows: First, with largest bounding box principle to determine the part's outer boundary. Second, with equal arc length discrete principle to part's outer boundary. Third, the judging cylinder radius value is determined. Fourth, outer smooth regions are determined by judging cylinder. Fifth, the start and end of outer smooth region are determined by split half approximation method. Sixth, adjacent outer smooth regions if should be merged is judged. Seventh, mapping Points is adjusted so that boundary mapping Points has a "convex" character. Eighth, uniform quadratic B spline curves is generated along mapping as curve of boundary of smoothing region. Ninth, the curvature extension curve of boundary control points is dispersed in accordance with arc length. Uniform quadratic B spline curves which is generated based on discrete points is as contour. Then the quadratic B spline surface as a Smooth Surface is generated by masked method to meet the requirements. Tests show algorithms can accurately determine the smooth region and generate to meet the requirements of smooth surface.