Papers by Author: Yan Cao

Abstract: Through the sheet metal digital information classification, induces the 2D graphics, 3D model, data forms, the information such as process design chart, file information is automatic extracted and meta data description information is interactively supplemented , data is stored in the database records, two kinds of query is designed for recorded data query and keywords retrieval methods.Engineering database system designed to define meta data, storage, retrieval, information coding and classification of four levels, combined with the engineering application of system requirements and function module design,interface of sheet metal unfolding system is developed.The system improve the design capability of sheet metal enterprises, reduce manufacturing cost, enhance the capacity of information management .

Abstract: MBD (Model Based Definition) technology is the development trend of digital design and manufacture. Design information includes geometric elements, annotations and process attributes. In the paper, the focus is concentrated on digital three-dimensional (3D) labeling of annotations. The 3D labeling system of product design information is seamlessly integrated with NX platform to define digital information of a 3D product model. The Key technologies of the 3D labeling system realization on NX platform mainly includes transformation of space coordinates, reference plane construction based on solid modeling and 3D dimensioning. NX internal program mode is adopted where the developed program is compiled and linked to generate the dll file whose codes are small and whose connection speed is fast. Integrated digital definition of a 3D model shortens product development cycle and improves product design and manufacturing efficiency.

Abstract: According to analysis of manufacturing enterprise coding requirements, Visual flexible coding system (VFCS) is proposed based on code classification theory. It has four function modules: code structure design, code segment & bit design, visual coding and interpreting, code query. Firstly, code rules are expressed by extendable XML format as data structure. Secondly, code design is regulated into two stages: code structure design and code segment design, so as to realize separation of code structure logical and contents. finally, code segment structure information is described as graphic nodes, using interactive graphics drawing for visual modeling, finite state machine algorithm are used implementing code structure interpreter.

Abstract: Spatial curved blades have been widely used in major aerospace manufacturers due to their light weight, high structural efficiency, high reliability, etc. However, their processing deformation, processing difficulty, and so on limit their use. In order to deal with the situation, flexible multi-point auxiliary supporting fixture for the processing of spatial curved thin-walled parts has become a major topic of current researches. The layout of positioning and clamping points of the flexible multi-point fixture direct affects the stiffness of clamping positions on the thin-walled parts to be processed. When cutting force is definite at a certain point in machining, the greater the stiffness at the processing positions on the part, the smaller the processing deformation due to the cutting force. Therefore, in order to reduce the machining deformation due to the poor stiffness, a suitable positioning and clamping layout is needed to improve the surface stiffness at the machining positions. Thus, the machining quality of thin-walled parts can be improved.

Abstract: Based on the Group Technology, Family part technology is adopted for standard part design, as well as parametric driven technology is adopted for non-standard part design, combined with assemble knowledge description and associated driven technology, typical structure parts library is realized by parametric driven assemble parts. For typical structure parts library in machine tool fixture, firstly, multi-classification and key words index is designed for management; secondly, several format files are managed in mapped directory by keywords and meta-data is generated by content description of those files based on analysis constitute of design information; Thirdly, process of making use of library is designed for top-down functional design. Typical structure parts library can maximize reuse the knowledge and parts of fixture design, greatly promote design efficiency.

Abstract: Blades are important components of aircraft engines. Free-form surface blade machining generally adopts sub-regional processing and cutting parameters vary greatly. Rational optimization of the cutting parameters can improve blade processing quality and efficiency in aerospace industry. To control the processing deformation of the blades, a method using artificial neural network and genetic algorithm is presented to optimize the cutting parameters. The method can reduce cutting parameter selection time and improve blade processing quality.

Abstract: Manufacturing Execution System (MES) is a job-shop production oriented management information system and the bridge between production plan management layer and job-shop control layer in an enterprise. Job-shop scheduling is the core module of MES, which direct affects the efficiency of production and management in the enterprise. According to the characteristics of discrete production management, a job-shop production scheduling system is presented that adapts to multi-variety small-batch production. A MES architecture for dynamic discrete production and its core modules are presented. Then, dynamic job-shop production scheduling problem is visually modeled and simulated based on Witness to realize optimal resource deployment.

Abstract: Aiming at the low machining accuracy, low efficiency, cumbersome programming process, strong empirism and great programming difficulty of special shape blades, a new NC spiral milling method of high-quality and high-efficiency is put forward to process aviation blades. Three methods of constructing spiral tool path are studied, i.e., constructing the spiral using interpolation in parametric domain, constructing the spiral based on a driving surface and projection technology, and segmentally constructing the spiral by plane intersection. By comparison and analysis, their advantages and disadvantages are presented. According to the characteristics of spiral milling, the principles and algorithms of interference-free cutter location calculation for space free-form curved surface are introduced and the focus is put on cutter contact point calculation algorithms.

Abstract: In order to improve the join fastness of silent chain, a new silent chain assembly method is proposed. It increases the capability that the silent chain stands against transverse vibration, reduces the meshing noise of silent chain without changing the space size of silent chain, by replacing the installing of outer link plate and pin as a press-fit configuration, and taking wire lock on the joint. The result of extrusion force comparative experiment showed that the extrusion force of outer link plate press-fit configuration was 2.5 times than gasket press-fit configuration. Through the platform contrast test, a noise test of two types of silent chain were made at the same speed, the result showed that the new silent chain drive more smoothly than the traditional one, the average noise level was decreased by 1.5dB. The two test results verified that the new silent chain assembly method is validity.

Abstract: Aiming at the problems such as updating difficulty, searching slowly and calling inconveniently occurs in use of current 3D Standard Part Library, the method to classify Standard Part data by function and the corresponding operations of each type of classified Standard Part data are analyzed firstly based on the real application and management requirements of the 3D Standard Parts Data. Then, the conception and the architecture of the data driven 3D Standard Part library is discussed based on the goal such as quick retrieve, automatic modeling and dynamical update of the Standard Part data and the methods as well as the key technology to develop the data driven 3D Standard Part Library are discussed based on the Pro/E and Access.