Research And Application Of Assembly Unit Division And Assembly Sequence Planning For Independent Rear Suspension

Assembly sequence planning refers to the planning and design of assembly sequence of parts in assembly body aiming at high efficiency,high quality and low cost.Intelligent assembly sequence planning is the key technology to realize assembly automation in intelligent factory,and it is an important means to improve production efficiency and product quality of enterprises.In this paper,the status quo and shortcomings of assembly sequence planning methods are analyzed.Taking the independent rear suspension of typical automobile parts as the research object,the assembly characteristics are analyzed,and the assembly sequence planning method and key technologies are studied.A set of assembly sequence planning automation method from product modeling,assembly unit partition to assembly sequence planning is formed,and the assembly process planning subsystem is developed.Firstly,the assembly model of the independent rear suspension is established and the assembly unit division method based on hierarchical assembly relationship is proposed.The assembly information needed for assembly sequence planning is analyzed,and the assembly model of independent rear suspension based on assembly adjacent matrix,assembly relationship matrix and assembly undirected graph structure is established.At the same time,aiming at the assembly characteristics of independent rear suspension,the non-orthogonal interference matrix of independent rear suspension is established through the technology of axial bounding box.Combining the assembly model of independent rear suspension and the weight theory,the hierarchy of assembly relationship is completed;according to the hierarchy of assembly relationship,the importance of assembly relationship in assembly process is fully considered and the weight of assembly relationship is given to determine the basic parts of assembly unit;The logical and fast division of the the assembly unit of independent rear suspension is realized by using the results of assembly unit basic components,the hierarchical relationship between the parts and the interference matrix.Then,after analyzing the advantages and disadvantages of ant colony algorithm,an assembly sequence planning method based on improved ant colony algorithm is proposed.Based on the theory of quantitative evaluation method,the assembly sequence evaluation function and assembly unit assembly sequence evaluation function are established respectively by analyzing the three evaluation indexes of assembly tool replacement,assembly direction transformation and assembly unit transportability.The advantages and disadvantages of basic ant colony algorithm and several typical improved ant colony optimization algorithms are analyzed.By comparing and analyzing the advantages and disadvantages of basic ant colony algorithm and several typical improved ant colony optimization algorithms,considering the difference between assembly sequence planning and traveling salesman problem,an improved ant colony algorithm is proposed.The solving models of part assembly sequence planning and assembly unit assembly sequence planning are established respectively on the basis of improved ant colony algorithm and evaluation functions.Finally,taking the independent rear suspension of a vehicle as an example,the model of parts assembly sequence planning and assembly unit assembly sequence planning based on improved ant colony algorithm is solved in MATLAB to verify the feasibility of the algorithm.On the basis of this research,the second development is carried out based on the enterprise PLM(Product Lifecycle Management)system platform,and the assembly process planning of typical automobile parts is completed.Design and development of planning subsystem.