Objective  The determination of dimensions of mortise and tenon joint is the premise of editing NC(numerical control) codes of mortise and tenon joint. It is also the foundation of realizing CNC (computer numerical control) machining of mortise and tenon joint. But the existing method of determining the dimensions of mortise and tenon joint by modifying the geometric models repeatedly is low efficiency and high difficulty, which has seriously affected the development of digital machining of mortise and tenon joint. Therefore, it is necessary to design an intelligent method of determining dimension of mortise and tenon joint.

  Method  This paper takes a modified lattice shoulder tenon as example. In the first, the mathematical models of lattices shoulder tenon were established and the dimension parameters of latticed shoulder tenon were extracted by parametric design ideas. Secondly, the correlation functions between dimension parameters of lattice tenon were established based on assembly constraints, which included two perspectives: position relation and match relation. Then, the correlation functions between dimension parameters and process constraints were established, and value ranges and preset values of part dimensions were settled based on process constraints, which included three aspects: NC machining technology, market research and process knowledge. Finally, taking the end dimensions of parts as the input parameters, integrating with associated functions, value ranges, and preset values, the relevant parameter function table was established.

  Result  By establishing the mathematical model of mortise and tenon joint, the dimension parameters of mortise and tenon joint were extracted. According to the assembly and process constraints of mortise and tenon joint, the correlation functions between dimension parameters were established successfully, and the value ranges and the default values were obtained. By founding the correlation function table of dimension parameters, the system can automatically output other dimension parameters by just inputting the cross-section dimensions of the mortise and tenon parts.

  Conclusion  The intelligent method of determining dimension of mortise and tenon joint was established on the combination of assembly and process constraints, that was also the scientific arrangement and reuse of process knowledge. This method can not only help to realize the intelligent determination of dimension, but also provide basic condition for intelligent manufacturing of mortise and tenon joints, even solid wood furniture processing.