Abstract:

A method for generating hierarchical exploded view automatically for complex product using the strategy of recursive iteration and depth-first searching hierarchical assembly sequences is proposed. To meet the requirements of assembly sequence planning (ASP), assembly reconstruction function that can conveniently define subassembly and edit assembly tree is designed. To avoid repetitive interference detection, the method of merging interference matrix based on assembly tree is studied, which can flexibly generate hierarchical structure-oriented assembly relation matrices by integrating the original ones. To reduce the complexity of large-scale ASP, the whole ASP task is divided into sub-tasks of hierarchies according to assembly tree. Within each sub-task, multi-rule screening (MRS) algorithm is applied to circularly construct a sequence, taking interference matrix-based geometric feasibility as precondition while parallelism, continuity, stability and directionality as optimization screening criterions. The proposed recursive explosion algorithm iterates depth-first searching hierarchical assembly sequences and real-time calculating the accumulative bounding box of exploded components to decide the displacement vector of each exploding component. The generated exploded view is full of sense of hierarchy, uniform in interval and compact in structure. An assembly planning system “AutoAssem” is developed on Siemens NX, and a gear reducer and big parts of a car are taken as examples to verify the effectiveness of the method and algorithm.

Key words: accumulative-bounding box, extended interference matrix, hierarchical exploded view, recursive iteration, assembly sequence planning