The Research Of DFD Method Based On DSP Under The Partial Destruction Disassembly Mode

With the environmental damage and shortage of resources becoming prominent increasingly, green consciousness is gradually increased. Green design emerges in such a background. Design for Disassembly (DFD) plays a key role in the demolition, repair and recycling of the products as an important part of green design. The process of DFD includes disassembly model building, Disassembly Sequence Planning (DSP), product disassembly evaluation and disassembly re-design for products. In the background of product disassembly and recycling at the end of the product life cycle, this paper makes a research of the DFD method based on DSP.Model building is basic for DSP and DFD. The points for the existing models of disassembly graph are analysed in detail. Constraints are classified and expressed particularly based on the existing disassembly hybrid-graph model with directed or undirected lines. It is clear and understandable, but not specific enough to represent all kinds of constraints. Combining with the matrix expression method of graph model, an improved disassembly hybrid-graph model is proposed with dashed, solid, black dots, arrows and other graph elements, and the information is expressed in the mathematical form of adjacency matrix and constraint information matrix in this paper.On the basis of the graph model, partial destruction mode in disassembly is introduced. Combined with the Unabled to be Disassembled Theoretically (UDT) problem to diagnosis and model reconstruction by Object Inverse-directed Method (OIM), a method based on target selection disassembly and DSP is proposed and the specific processes are described. In order to increase the efficiency of disassembly under the situation of selective disassembly, partially constraints between product components are destroyed in partial destruction mode. However, environmental damage arises from the destruction. Therefore, improvements are considered to avoid the negative effects and ensure the disassembly efficiency. Keeping the lowest investment and getting the maximum benefit are the optimal target of disassembly and recycling while investment and benefit are always not the same under DSP for different modes. Meanwhile, the meaning of disassembly investment and benefit is different depending on different disassembly values. So, in the form of single and multi-objective evaluation, various disassembly plans are evaluated with the evaluation factors of disassemble time, number of disassembly tools, disassembly costs, disassembly noise and disassembly solid dust. Economic and environmental factors are considered respectively and jointly. Multi-index evaluation system based on the Analytic Hierarchy Process (AHP) weight distribution and multi-index evaluation system based on Pareto dominated degree are established to evaluate and obtain the required optimal disassembly plan. Improved disassembly objects and improving ideas can be provided from the optimal disassembly plan under partial destruction mode.Based on the optimal disassembly plans under different disassembly modes above and the DFD idea of "product design-product use-product disassembly-product redesign", especially for the optimal disassembly plan under partial destruction mode, improving design for relevant components and constraints is implemented to improve the relevance and purposiveness of DFD. Essential information of physical dimension and constraint details is gained from disassembly graph mode and disassembly information matrix.A case of electric corkscrew is shown to test and verify the DFD method based on DSP under partial destruction mode proposed. DSP, disassembly plan evaluation and partial improvement of DFD are explored to the electric corkscrew. The results of the analysis indicate that both of the disassembly economy and the environmental protection are promoted via the proposed DFD method in this paper.