The Study About Modeling Method Of Assembly Model Based On Top-Down Design

Aimed at the faultiness of computer aided design system and existent problems of Bottom-up design, assembly modeling based on Top-Down design method is adopted to design, on the basis of study of Top-Down design method and assembly modeling technology. First, this paper introduces the origin, concept and research actuality of Top-Down design method, key technologies which sustain Top-Down design method. Assembly model is the key to achieve Top-Down design, so its definition, sort, and expression are deeply studied in the paper. Based on above, the assembly feature and assembly relation are then studied. According to thought of Top-Down design, in order to accomplish the parts' abstract expression above assembly plane and the assembly modeling expression based on abstract parts, the concept of assembly structure tree is put forward, and is applied to express assembly structure model. Thus it makes complicated problem simple. Then skeleton model (SM) is introduced into assembly structure model. Design information is passed through SM, and then parts are designed in detail by taking assembly conceptual prototype as a skeleton of product. In the end using the theory and methods above, a portable drill is designed. Yet standard parts base and parts in common use are built, so it improves design efficiency and speed. The result of emulation shows there's no interference into the assembly model, thus it validates the feasibility and correctness of the theory and methods above.