Development Of High-speed Cutting Database System With Hybrid Reasoning

High-speed cutting is an advanced manufacturing technology developing rapidly in recent years. It can prompt the manufacturing process and the renewal of equipment, improve production efficiency and quality significantly, and reduce the manufacturing cost and process time by over 50%. As an advanced manufacturing technology, high-speed cutting has not fully developed. There is less data related to machining parameters and process instances and the data accumulated in conventional machining cannot be used directly. One of the main problems in the application of high-speed cutting is that there is no complete and practical high-speed cutting database.The study of the high speed cutting database has a great value in current mechanical engineering. It makes a great impact on the application of high speed cutting technology. The principal aim of the present study is twofold: (1) to discuss the model of the high-speed cutting database in order to realize the integration, intelligence, practicality and network of the cutting database; (2) to build a high-speed cutting database that meets the contemporary needs so that the user can obtain the whole solution of one working operation from this database, including the information of machine tools, cutting medium, cutting tools, cutting parameters, etc.The high speed cutting database system is studied in this dissertation from two aspects: theory model and system developing. Based on the theory model of high speed cutting database system built, the B/S mode high speed cutting database system is developed. The theory model presented includes: knowledge-based integrated manufacturing reference model; the method for knowledge base building; case parameters model; STEP-NC based case coding scheme. In the development of the high speed cutting database system, the following databases are built: material classifying database; material standard database; material database; turning operation case base; milling operation case base; hole making operation case base. The hybrid reasoning combining rule-based and case-based reasoning is realized. The method for computing cutting speed on the base of workpiece materials or cutting tool materials similarity is put forward. Finally, the B/S mode high speed cutting database system is developed.A reference model for knowledge based integrated manufacturing is put forward. Today, many a new manufacturing mode such as concurrent engineering provides many important benefits such as greater process flexibility. But these realizations of integrated manufacturing mostly stay on information and source level. Therefore, a reference model to realize the function integration is needed urgently. By analyzing CIM reference models, knowledge based integrated manufacturing model is put forward. This model consists of three models and three layers. And the corresponding model realizing methods are given, which can offer unified machining knowledge to support function integration and make the knowledge sharing available.The method for knowledge base building is put forward. The ability of intelligent systems to solve problems mainly depends on the knowledge quantity and quality that they have. Then how to store, manage, organize, maintain and update knowledge efficiently, and how to reason and solve problems using these knowledge efficiently, will directly influence the performance of the intelligent systems. The study of the method for knowledge base building can help to direct knowledge base establishing, and to speed up intelligent system developing. By analyzing the software developing process and on the basis of the case parameters model presented, the method for knowledge base building is given.The architecture of the high speed cutting database system is built. The system makes the case base the center, and provides work steps information. In the development of this system, object oriented methods and structural methods are used. By combining UML case diagram and class diagram to express the composition of machining unit, with the IDEF0 diagram to express function of system, with the IDEF3 to express the cutting tool selecting process, the architecture of high speed cutting database system is established.Rule-based and case-based hybrid reasoning is realized. Reasoning means the process during which a new judgment is obtained from old judgments. Today, in artificial intelligent system, reasoning is realized by computer program, and this computer program is called reasoning machine. By analyzing the normal reasoning methods, the mechanism of rule based and case based reasoning is discussed, and the practical methods are given.The scheme of STEP-NC based case coding is put forward. Speed of case based reasoning depends on case coding, and therefore influences the practicability of the system. The case code in the high speed cutting system adopts flexible code. This coding method borrows the coding thought from IP address coding, which adopts hierarchical coding scheme, and it makes case code practical and efficient. First the contents of case code are determined by analyzing STEP-NC data model, then the process of case retrieve is further discussed, which includes two indexing methods: case attributes indexing and code indexing. Retrieving case by indexing code makes the building of a large practical case base possibly. At last, turning, milling and hole making operation case coding schemes are given.The high speed cutting database system is developed. Three levels application program model is adopted to develop high speed cutting database system. According to the system function logic level, the system is divided into three layers, namely, express layer, function logic layer and data access layer. Express layer corresponds with user interface layer, function logic layer is responsible for accessing data and sending the data to user interface, and data level corresponds with database. First the database is built, then the interface is determined, and thirdly the program is developed.High speed cutting experiments are done. In the high speed cutting database system, the cases are collected mainly from manual handbooks of various cutting tools manufacturers. The experiments can provide some cases on the one hand; on the other hand, the parameters provided by high speed cutting database can be evaluated. Most importantly, the cutting parameters obtained by similarity calculation are verified.