00 Digital Pre-assembly Simulation Technology

In 21 st century, manufacturing enterprises face with increasingly intense competition of global market. The purpose of research on digital pre-assembly technology is to offer an environment and tools to evaluate product assemblability, reduce modification or rework caused by design error, shorten product development cycle, cut the product cost and enhance competition ability of enterprise. Based on the analysis of research situation of digital pre-assembly technology, an architecture of digital pre-assembly system is given, which is open, reconfigurable, reusable and extendible.A new model of digital pre-assembly system combined hierarchical relation and connectivity relation is studied based on analysis of assembly model. An assembly model with layers is presented by using feature technology. A database of feature template is built, a resolution method which different three-dimensional CAD models can be inputted DPAS(digital pre-assembly system) is put forward by feature identifying, and then the system examples is given by using UG.The task of assembly path planning is to find an optimal, collision-free assembly path for part from the feeding position to the assembly position. In this paper, assembly path planning is studied with disassembly path planning for product, the disassembly direction for part can be obtained by using methods of routine, automated analyze or interactive input. And then global feasibility is assured by using mapping method. In the end, the technology of collision detecting combined Bounding Box and Octree method is used to assure the components along their disassembly direction in the whole assembly simulation.According to the theories we have developed a Digital Pre-assembly System (DPAS) in our lab. A case study is also introduced to illustrate it.