| As “Made in China 2025” proposes that digital manufacturing and intelligent manufacturing are the main development directions and the rapid development of numerical control processing technology,Computer Aided Process Planning(CAPP)has been widely used and has occupied a very important position.The description of parts information,tool and machine selection are the basis for CAPP’s process decision making.Therefore,with the background of NC machining technology,this paper studies some key technologies about the intelligent CAPP system,such as establishing the part information model and the selection of feature processing scheme,tool and machine selection,process sequencing optimization.And a tool-centered decision system was established to make the tool and the machine contact each other.According to the definition of features,parts design and manufacturing process,the concept of processing feature is proposed.It unifies the product design features and intermediate features that produces in the manufacturing process.What’s more,it establishes the contaction of parst features,machining methods and tools.Taking the process feature unit as the core,the EER modeling method is used to establish the parts information model.It makes the unit design.and manufacturing information description unify.With the process feature database and reverse reasoning,this paper proposes a method to generate multiple feasible machining plans and their selection priorities for the features.It can provide the basis for the dynamic selection of the feature processing plan in the process optimization and the reasoning of the candidate machine tools.Using object-oriented thinking and database technology to establish the ORDB of the tool and the machine.And establishing the correspondence between the tool and the machine.The choice of the machine is divided into two levels,including the selection according to the ORDB of the tool,and the selection according to the machine specification model.In addition,the algorithm flow is established to improve the efficiency of the machine tool selection.A combination optimization method is proposed,which consists of dynamic selection of processing plan based on selective priority and optimization of process sequencing based on genetic algorithm.With the lowest processing cost as the optimization goal,the mathematical model of combination optimization is established.And it can obtain an optimal route and several approximate optimal routes.In addition,through the examples of a splined sleeve part,the rationality and feasibility of this combination optimization method are verified.Finally,using VB6.0 and SQL Server as development tools,an intelligent CAPP prototype system was developed,which introduces the operation flow and working interface of each module. |
