Research On Assembly Planning Technology For Complex Product

With the development of large and complex products in the direction of intelligence,precision and opto-mechanical integration,the structure of product parts is becoming more and more complex,such as spacecraft,aircraft,ships,radar,etc.In order to improve production efficiency and product competitiveness,and to cater to the globalization and networking of manufacturing,the virtual manufacturing technology of products becomes increasingly important.Virtual manufacturing,supported by computer simulation technology and threedimensional modeling technology,uses the virtual model of the product to perform full life cycle simulation of the product in the product design process,and evaluates the overall performance and manufacturability of the product,thereby improving prediction and decisionmaking ability to achieve balanced and optimized performance of all aspects of the product.Assembly is a key part of the manufacturing process,so virtual assembly can performing preassembly at the product design stage to verify the accuracy of the assembly process.Under this background,this paper developed a three-dimensional model-based assembly sequence and path planning system,and achieved some results.The main research content and results of the paper are as follows:(1)The system structure and function model of the assembly sequence and path planning system are established,the work flow and data flow of the system are analyzed,the overall functional modules of the system and their relationships are introduced,and the key technologies of the system are studied.(2)An assembly information model for large and complex products is established.The priority connection matrix and its calculation method are proposed and expressed.The Constraint set and cooperation direction set and their classification representation rules,assembly hierarchy model are proposed and expressed.The algorithm for solving the basic parts is expressed.The expression management mechanism of the assembly information model is established.Geometry,constraints and process information are organized and expressed to achieve effective management.(3)Cooperation direction set and interference detection technique are used to achieve assembly path.Related rules for assembly path generation are established.A mixed detection method which includes a rough interference detection based on axis-aligned bounding box and an accurate interference detection is proposed.The concept of interference set was proposed,and the maximum bounding box of parts and the global containment box are used to solve the assembly interference set.The solution methods of assembly space and search step are proposed.A specific method for reasoning the assembly path based on real-time interference inspection and cooperation direction set is proposed.(4)Parallel ant colony algorithm and the similar reconstruction technique are used to achieve the assembly parallel sequence.The effects of assembly operation,process feasibility,assembly efficiency,assembly environment and other factors on the optimization of assembly sequence are comprehensively considered,so as to establish an effective evaluation system for assembly sequence solution.Based on this,the objective function and fitness function of the parallel ant colony algorithm are established and expressed.A specific strategy for solving assembly sequences based on parallel ant colony algorithm is proposed.The similar reconstruction technique for generating assembly synchronization sequences is studied.A method of assembly sequence oriented to reconstruct and generate synchronization sequence is established and expressed.A calculation method for comparing the similarity of assembly sequences based on Spearman rule is proposed.The rules and method flow for generating nonlinear synchronization parallel sequences based on linear sequence reconstruction are proposed.On the basis of the above research,the programming tool MFC and CREO secondary development tool Pro/TOOLKIT are used to develop the assembly sequence and path planning prototype system based on the three-dimensional model.The mechanisms and key technologies involved in the system are verified through application examples.Finally,the practicability and efficiency of generating assembly sequences based on parallel ant colony algorithm are analyzed through comparison.