This technology come of Germany, our nation adopts the correlative standard equivalently. Tabular layouts of article characteristics prescribe the expression format of data, it made product data interchange among different system expediently and expressing information set by a fixation format table [10]. This is a kind of design method by which achieving a new part instance by change characteristics value and carry out automatic design effectively. Tabular layouts of article characteristics may describe layer information of parts, it derive parameterized part main model and finish instantiation of model.  3.3 Constructing Standard Part Main Model and the Library Implementing Flow In the light of the library design thinking, establishing standard parts main model is that analyzing the part, modeling entity part and make the variables parameterization. The modeling process is an important step by which realize part  automatic design, we should consider part construct character and engineering design require [11]. Whether the restrict relation of parameter is rational associate with preciseness of design. The restriction relation should be adjusted properly according to design demand in necessary time. Standard part main model was established as follow: firstly, we design corresponding entity model in CAD system, labeling design parameter in sketch phase so that the parameter present to variable table. Then opened the part variable table and edited the variable name to make it possess engineering sense or construct sense, set up relation expression in formula column [12]. Secondly, establishing tabular layouts of article characteristics in database through the function providing by user module, character parameters in tabular layouts of article characteristics are corresponding to variable in variable table, when designing part, we can call parameter value from database to make model instantiation, or saving a new instance in database. Calling main model, reading and writing parameter value are carried out by user module, so the system has expansibility. Figure 5 showed the standard parts library prototype subsystem.    Fig.5 Standard parts library prototype   The table of database was principal and subordinate construct, subordinate was main model table in which recorded information of main model, each table corresponding a type of part expressed by the main model, a record expressed a part instance. Principal table saved the type information of main model in which recorded subordinate table, a record expressed a type of part, so part type could be searched. Principal table and subordinate table set up relationship through common field, and found necessary restrict to keep data coherence. User module may display data and read-write data, it provided an interactive input window by which user input interrelated parameter. These parameters value would update main model in light of mapping relation. Standard parts library may display parameter value of instance, if the new part was required, designer may call main model by interface and evaluate for each parameter based on design demand, then the data would be saved in database to increase a new part instance. 
4. CONCLUSIONS  The project construct standard parts library make use of modeling function and model driving function of CAD system based on part main model and tabular layouts of article characteristics technology, accordingly all standard part may express by main model, designer make the best of design resource, part development efficiency would be improved, it is important for series part design and provided a effectual means for standard part data management.  REFERENCES  [1]  ISO 13584-1: Industrial automation systems and integration-Parts library, Part 1: Overview and fundamental principles, 1999. [2]  ISO 13584-42: Industrial automation systems and integration-Parts library, Part 42: Description methodology, 1998. [3]  Guoning Qi, Xinjian Gu. Mass Customization technology and its application [M], China Machine Press, Beijing, 2003. [4]  Yangdong Wu, Junhe Yu, Guoning Qi. Web-based variant design system [J]. China Mechanical Engineering, 2004, 15(19): 1720-1725  [5]  Yunfu Cao, Feng Li. Information model of parts library and its representation based on PLIB [J]. Journal of computer-aided design & computer graphics, 2002, 14(6): 312-316 [6]  Yang dong. Research on the Application of ISO13584 [J]. China mechanical engineering, 2001, 12(10): 1117-1122 [7]  Junhe Yu, Guoning Qi. Product information modeling based on parts library standard [J]. Computer Integrated Manufacturing Systems, 2004, 8(4): 263-268 [8]  Guoning Qi, Qinghai Yang. Research on Methods of product development and design for mass customization [J]. China mechanical engineering, 2004, 15(19): 1697-1701 [9]  Neng-jian Wang, Chang-hua Qiu. The design of managing and application of the standard part library [J]. Journal of Harbin Engineering University. 2000, 机械三维标准件库的研究英文文献和中文翻译(2):http://www.youerw.com/fanyi/lunwen_55801.html