Algorithm Research And Application Development Of Soft Interference Checking On Automobile Panel Dies

Due to the size deviation of castings, even if the mold’s design size is correct, interferences may exist when the real mold is assembled. So the clearance analysis should be performed to meet manufacturing requirements when the mold is finished to be designed. Using 3D modeling software to design the mold can reduce the difficulty of interference checking, but it is still inefficient and unreliable by manual operations, which will extend the design cycle. This problem can be solved by using an interference checking application. NX Application provides this function, but it can’t meet all the requirements, such as setting multiple critical distances, calculating all the interference locations and so on.Through reading many related papers and analyzing the demand of the 2014 industrial transformation and upgrading strong base project “Automobile Automatic Multi-position Precision Progressive Die”, the key technologies were studied and Clearance Analysis Wizard was developed which is based on NX platform.In the traditional soft interference checking method, results are judged directly by the minimum distance between complicated objects. This paper proposed an interference checking algorithm based on information facets, by studying basic theories and related technologies about collision detection and considering the mold’s design requirements. The surface of checking solids was discretized into large numbers of triangle facets, and distances between complicated objects can be obtained by computing distances between triangle facets. In order to check interferences between casting surface and machining surface synchronously, surface information was saved into triangle facets. This algorithm has a linear time complexity, and it is highly efficient even though the mold is very complex.In order to improve the algorithm’s efficiency further, spatial grid were used and triangle distance computation was limited within the same or adjacent grid cell. The method of triangle distance computation was simplified through building local coordinate system, and spatial triangle distance computation was converted into coordinate calculation and intersecting detection of plane triangles. Parameters were optimized by analyzing the influence of triangle facet size and spatial grid size on calculating time. This algorithm is very efficient, and it can be used to check N body’s interference quickly.The NX-CAW application contains preprocessing module, solver module and post processing module. Every module is independent with each other, which ensures high maintainability. To verify the application’s high efficiency and accuracy, a wheel house panel drawing die was taken for example and solving time and interference results were analyzed. Compared to NX interference checking module, NX-CAW can get more detailed soft interference information and all the interference regions, which means more significant. Therefore, NX-CAW can meet the requirements of automobile panel dies’ soft interference checking, and it can be used to improve design efficiency and reduce design errors.