A novel connector-knowledge-based approach for disassembly precedence constraint generation

Maintenance and recycling of a product often requires its disassembly. To have a successful disassembly process, it essentially asks for a comprehensive study of disassembly constraints. Related studies have revealed that precedence constraints offer important information to remove the infeasible disassembly plans to attain practical and feasible ones. Standard connectors play an important role to fasten two or more components together. By analyzing the disassembly knowledge and experiences of connectors, it is possible to derive precedence constraint directly. In this paper, different approaches for disassembly precedence constraint generation are first reviewed. Then, a novel connector-knowledge-based approach is presented for automatic generation of disassembly precedence constraints. As a preliminary research, threaded fasteners and keys are analyzed and corresponding precedence rules are extracted. By integrating this novel knowledge-based reasoning (KR) with the geometric reasoning approach, both approaches are utilized to their best advantages. Necessary disassembly constraint information can be automatically generated with less computational complexity. A typical shaft assembly in a gear reducer is selected as the case study to illustrate the proposed approach. The result has shown that this KR approach is simple and efficient in generating reasonable disassembly constraints.