The Research On Assembly Sequence Planning Based On Step Cad

In this study,a completely automatic assembly sequence plan is developed.The assembly sequence plan can directly extract geometry information from STEP CAD file,then generate the feasible assembly sequence whose the number of reorientation is a minimum in assembly direction.The study is divided into three parts.The first part of the study,in order to extract geometry information from STEP CAD file and test out parts all the possibility of collision in assembly movement along spindle assembly direction,an algorithm and software about extracting geometry is developed. The software developed directly collect a designed product assembly STEP CAD file,input to the computer and output six degrees of freedom matrix model that describes all the possibility of collision relations between parts in assembly process along the six spindle direction.The second part of the study, the first part developed software synthesize an assembly sequence plan which is based on the genetic algorithms.The improved assembly sequence plan is then used to automatically find optimization or nearly optimal assembly,put assembly direction number of reorientation as user defined criteria.Complete assembly sequence scheme will directly put a product assembly STEP CAD file as input and output the geometry feasible assembly sequence,it depends on minimum of assembly direction adjustment.Research of the third part, through a case study demonstrates that the adjustments of assembly direction effect assembly time, to the assembly of the machine and artificial assembly the same way.Case study results show that the number of assembly reorientation is important for assembly time at assembly sequence.The results support basic research hypothesis that use more the direction of the assembly adjustment,need more assembly time.Case study confirm that use automatic assembly sequence scheme to reduce assembly the number of reorientation, It is very important and effective.