Research On Network Collaborative Digital Preassembly Theory And Key Technologies

With the increasing competition in global market, the process of product design and manufacture can't be accomplished by an individual corporation which is instead of teamwork of several cooperative corporations. As a link between product design and process plan, assembly concerns many people and technical fields. Network collaborative digital pre-assembly system can bring the designer, technologists and manufacturers around the world together to take part in the approach of assembly design and verification cooperatively. Through constructing the virtual product simulation and test environment beyond the limit of region and time, the assembly activity can be realized virtually in the computer. The assembly process simulating, assembly sequence planning and assembly tolerance analyzing can all be analyzed under the aid of computer, which support engineers in different places and different fields to work on the assembly design, planning and analysis cooperatively.Based on the analysis of backgrounds of concurrent engineering and virtual manufacturing, the significance of collaborative digital pre-assembly technology is expatiated in this thesis. According to the characterstices and demand of collaborative design, a reconfigurable, reusable and enlargeable system which supports multi-disciplines engineers in different places to carry out a collaborative digital pre-assembly is put forward. The function modules and structure of this system as well as the workflow of digital pre-assembly under the network environment are analyzed.Considering the characteristics of collaborative assembly process, the product feature information is classified. And a precision-oriented digital assembly model is put forward based on the tolerance expression of part feature. This model has five layers, which is made up of hierarchical relation layer, connectivity relation layer, feature information layer, feature element layer and triangle face layer. By establishing a relation chain among the elements in a layer and information mapping among all layers, the product assembly information can be well integrated. Information transformation technology from CAD system to digital assembly system is studied, a method of automatic generation of dimension chains in digital assembly environment is brought out.Based on the diversity and complexity during product assembly process, a reconfigurable product digital assembly environment model is put forward. This model has three layers which are device layer, middle layer and part layer. After categorizing the assembly environment information, the formalized expression of the model is given out and a digital pre-assembly environment is built by the object-oriented technology. The data structure and configure structure of the virtual equipment model in the environment are given, and the key technologies such as the motion simulation and collision detection are broken through.A fuzzy evaluation method of assembly design scheme under digital assembly environment is brought forward. Based on analyzing the characteristics of product assembly designing and planning process including product design (assembly design), manufacture (assembly process), service (assembly maintaining) and environment (pollution abatement, reusable), many factors assembly related are analyzed and classified from dynamic assembly process and static assembly environment under digital assembly environment, and the influence models of assembly quality, time, cost, service and environment are built. The subjection function and weight of each factor are given, and a synthetic evaluation method for product assembly quality, time, cost, service and environment by fuzzy analytical hierarchy process is studied.A method of building a collaborative digital pre-assembly platform is put forward, and the collaborative technology of system is studied. According to the characteristices of collaborative digital pre-assembly, a reconfigurable multi-agent dynamic organization of collaborative assembly is put forward. The action modeling of each intelligent agent that the system composing is build with object oriented-Petri net, and then the communication of each agent is analyzed. The dynamic organization model and process model of collaborative assembly are built, the key technologies of communication and real-time collaboration among multi-agents are studied, and the collaborative digital pre-assembly workflow is also given in this thesis.According to the collaborative digital pre-assembly theories mentioned above, an network collaborative digital pre-assembly system is established by COM technologies. An instance of XXXX gearing system is taken for example to verify the collaborative assembly design and process planning.