Product family design for PDM system

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Product family design for PDM system

firstly, the design process of product family is discussed. A product family information model based on tabular layouts of product characteristics in PDM is proposed. By establishing the real-time communication mechanism between PDM and 3D CAD system and the unified product information model, the parametric product family design based on 3D model in the pdm/3d CAD Integrated environment is supported

product family refers to those technical objects (complete machines, components or parts) whose parameter levels are divided according to certain laws within a certain application range and whose functions are the same in the same way. These technical objects should be manufactured with the same manufacturing methods as possible [1]. The product family is characterized by a variety of parameters and performance indicators to meet the needs of different users. These parameters and performance indicators have a certain common ratio difference. The development strategy based on product family is one of the effective ways to solve the problems of the proliferation of parts types and high manufacturing and management costs faced by many enterprises in pursuit of meeting diversified customer needs. As an important application software integration platform for manufacturing enterprise informatization, PDM must effectively support product family oriented design, so as to easily produce a series of products, meet different customer needs, realize technology reuse and technology transfer, so as to effectively reduce the innovation risk and development management cost of new products, and create a complete product chain through the complete product family and new material industry, Covering a variety of market demands, shaping a good product image and corporate image

I. product family design process [2]

product family oriented design designs a product family model that meets the needs of a certain customer group according to the market forecast. On this basis, according to the customer order, it provides users with personalized customized products through the configuration and modification of the product family model. The product family model is a dynamic product model (Figure 1 shows the product family structure model). Logically, product family model consists of function model, principle model and structure model, which can be regarded as different views of product family structure. Physically, the product family model is composed of geometric characteristics, physical characteristics and manufacturing characteristics. The tree structure of the entity shows the topological structure of the product family. Constraints not only define mapping constraints between view objects, but also define Association constraints between entity objects and variant parameters, and between entity parameter values

the design process of product family is a mapping solution process from customer requirements to product family structure model, as shown in Figure 2. First, collect user needs, and extract common needs and individual needs from them; Transform user requirements into design requirements of product family and establish corresponding functional structure. The overall function of any product is composed of some lower level sub functions, and the overall function of the product is realized through the realization of these sub functions. The method of product function analysis is to use the top-down decomposition method to determine the sub functions of each level of the overall product function, and construct the product function tree in Figure 1

then the principle mapping is performed for each functional unit through the function principle mapping unit, and then the principle model of the product is combined. The principle analysis should follow the principle of function decoupling to find the principle module, and consider the realization of multiple feasible principles of a function node, so that it can be configured according to different needs in the future. The result of principle analysis is to establish the function principle relationship tree in Figure 1, that is, the function node is taken as the root node of the tree, and each principle realizing the function is connected with the function root node as a leaf node

product structure planning analyzes the structures that use the principle to realize the required functions for each principle leaf node in the product function principle tree. These structures are connected to the principle node of the function principle tree as leaf nodes to form a function principle structure relationship tree, which is used to express the product structure of the product family. If there are multiple structures for a principle or structure, these structures should be placed in the function principle structure relationship tree

finally, based on the variable parameters extracted from the dynamic product model, determine the customization parameters of the product family, and further plan the coverage of the product family, that is, determine the customization range of the product family. The existing products of the enterprise can be used as product examples of the product family, providing design reference for the design that the Variant 3 countersunk screw should not protrude from the surface of the part. Establish the product instance set of product family, analyze the variation range of the main parameters of product instances in the family, and provide reference for determining the customization range of product family

2. Product family information model

in PDM, in order to effectively retrieve parts and carry out variant design, we use the mechanism of thing characteristic table to describe product family (as shown in Figure 3). The article characteristics table is an ASC Ⅱ file that records the article characteristics in a fixed format and describes the characteristics of parts and components in the form of tables in order to establish the database of parts and components. Because the parts and components based on the tabular layouts of article characteristics adopt a unified description format, information can be exchanged between different systems, making the parts and components system open and easy to expand. A reasonable thing characteristic table not only provides designers with as complete parts information as possible, but also facilitates the variant design of products, parametric query of parts and design, reduces the waste of resources caused by repeated development, and improves the reuse rate and design reliability of green demonstration plants, green demonstration parks, green products and green supply chain demonstration lists [3]

in the product family information model shown in Figure 3, we establish a parameter table for the product family model that complies with the national standard gb10091 general rules for the preparation of the table of characteristics of things (the general rules for the preparation of the table of characteristics of things in gb10091 are formulated with reference to the din4000 series of standards for the table of characteristics of things formulated by Germany in 1971 as the basis for the standard parts information base). The parameters in the parameter table are mapped to the geometric characteristics, functional characteristics and manufacturing characteristics of the entity in Figure 2. Parameters are divided into independent parameters and non independent parameters. The value of independent parameters is obtained according to the user's needs or assigned by the parent parts. The values of dependent parameters are derived from the values of independent parameters and follow the constraint definitions in Figure 1. In principle, after each row of parameters in the parameter table is given a specific value, each specific product instance can be clearly described. However, in order to reduce the types of parts and components and prevent engineers from automatically selecting one of those parts that have not been used without approval or approval, or adding new parts to the PDM system, resulting in a proliferation of parts, only when the lines in the parameter table need to be assembled and used, PDM will generate product instances [4] based on the values of each

parameter on the basis of the product family model, as shown in Figure 3. Otherwise, the row in the parameter table only indicates the recommended value for a row of parameters by the product family designer, not for the product instance, as shown in L in Figure 3

the attributes of the product family model describe the public information of the whole family, such as the name and standard number of the product family, which are shared by product instances. Product instances can also have their own attributes. The document of product family model is the main document based on parameters, including 3D model, 2D engineering drawing, process file, NC code, etc. The product instance combines the data of the row corresponding to the parameter table with the main document of the product family model to derive various related documents. In order to reduce the number of unnecessary documents in PDM, product instances share the documents of product family models. When browsing or 3D model files in product instances, PDM notifies the browser or 3D CAD and other applications according to the parameter values to carry out dimension driving and parameter calculation to obtain the document view of product instances

III. product family design in pdm/3d CAD environment

fully supporting product family design is one of the main contents of pdm/3d CAD integration research. We have established a real-time communication mechanism between PDM and 3D CAD systems and a unified product information model to realize product family design based on 3D models in the pdm/3d CAD Integrated Environment (the implementation principle is shown in Figure 4). Support users to use 3D CAD and PDM for parametric design of product family models at the same time, and realize information synchronization through two-way information interaction

in the 3D CAD file, it is consistent with the product family information model in PDM. It also establishes a parameter table for the product family model, as well as the mapping relationship between the geometric dimension, functional characteristics, manufacturing characteristics and parameters of the model. The integrated plug-in middleware builds a bridge between PDM and CAD, and maintains the consistency of product information in PDM and CAD. The integration plug-in is divided into two parts: the server and the client: the server is an executable file, which is the distributor of messages from both sides of the integration; The client consists of a dynamic library and OCX controls. It is responsible for sending messages to the other party and responding to the received messages to complete the corresponding functions. The client is embedded in CAD and PDM applications. When processing messages, it needs to call the underlying call interface provided by CAD and PDM. According to the coupling degree of messages, messages are divided into modal and non modal to improve the performance of message processing. The modal message requires the destination application software to return after processing the message, and the source application software is in a waiting state. Non modal requires the target application software to return after receiving the message, and then process the message. After the message processing is completed, the server sends the results of processing in its modern vehicle model to the source application. The type, format and semantics of messages are described in the data middleware using the markup language XML. Because XML is a neutral format language, the type of messages has strong scalability and can be used in different 3D CAD applications

pdm/3d CAD Integrated environment automatically keeps the product family model object of PDM system consistent with the parameter table in 3D CAD model file. In other words, the modified parameter values, increased and decreased parameter lines of either party will be automatically transferred to the other party, and the corresponding product instances will be changed through parameter driving according to the parameter mapping relationship and the parameter transfer mechanism. In addition, 3D CAD can also request to execute the functional components in PDM through the integrated plug-in middleware, which can integrate the data management, design process management of PDM system and the design modeling of 3D CAD system

IV. conclusion

with the formation of the global market, the focus of enterprise competition has focused on how to better meet diversified customer needs. Taking kmpdm as the platform, we have realized the integration with a variety of 3D CAD (such as kmcad 3D, solid works, solid edge, etc.), and supported the parametric product family variant design function under the integrated environment. The practical application of this set of solutions in enterprises shows that it can effectively improve enterprises' rapid response to customers' diversified needs and reduce the diversification of internal parts


[1] wangzhongbin, wangningsheng, yewenhua Research on a product family information model supporting MCM Journal of Nanjing University of Aeronautics and Astronautics, 2002, vol34 (3): 301 ~ 305

[2] liuxiaobing, dongjianhua, sunwei Research on product family oriented modeling technology Journal of computer aided design and graphics, 2001, Vol.13 (7):13 ~ 18

[3] qiguoning, schottner J, guxinjian, et al A product modeling method for mass customization CIMS, 2002, VOL8 (1): 12 ~ 15

[4] Anderson d m, pine Ⅱ BJ, agile product development for mass

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