Hierarchical exploded view generation based on recursive assembly sequence planning

Abstract

A method for automatic generation of hierarchical exploded view for complex products based on recursive search of multi-level assembly sequences is proposed. Two interference detection methods based on extruding bounding face and feature face are presented to narrow the detection range and quickly acquire the extended interference matrix, which is used to solve the problem that some components have to be assembled in oblique directions. The method of assembly reconstruction is developed to define a subassembly and edit an assembly tree. The method of merging interference matrix is proposed to flexibly generate hierarchical assembly relation matrices and avoid repetitive interference detection. The whole assembly sequence planning task is subdivided into the subtasks of the customized levels so that the complexity of a large-scale sequence planning is reduced. The multi-rule screening algorithm is applied to each subtask, where interference matrix-based geometric feasibility is taken as the precondition and parallelism, continuity, stability, and directionality as the screening criterions to circularly construct a satisfactory sequence. The recursive explosion algorithm iterates depth-first search for hierarchical assembly sequences and calculates the accumulative bounding box of the exploded components to decide the position of the exploding component. The generated exploded view is uniform in interval, compact in structure and clearly hierarchical, based on which hierarchical assembly trace lines and explosion simulation can be easily implemented. An assembly planning system “AutoAssem” is developed on UG NX, and a gear reducer and the big parts of a car are taken as examples to verify the effectiveness of the methods.