AutoCAD's tile function is not suitable for the creation of the standard parts library. This is because, whether it is a national standard or an enterprise standard, the same series of standard parts only have similar structures and shapes, but they are not simply scaled by the whole. AutoCAD software does not have a parametric drawing function. Every detail, every line, and every size on a part must be manually manipulated, and cannot be updated by a size-driven graphic. When the tile is inserted, only the overall scale can be scaled. If only one tile is created for a series of standard parts, it is obviously impossible to obtain standard parts of other specifications by scaling during insertion, after inserting into the drawing. It is also necessary to perform various editing operations to obtain the graphics of the required standard parts. This obviously does not meet the requirements of the standard part library for the design work; if the drawing of the standard parts of all specifications is drawn in advance, the workload of the library will be It will be very large, and each standard part is saved as a graphic file on the disk, which not only takes up a lot of storage space, but also is inconvenient to retrieve when calling. If the standard is revised and you need to change the size of a standard part, you need to open its corresponding graphic file for editing and modification. The maintenance of the standard parts library is very difficult. Therefore, the tile function of Auto-CAD is difficult to meet the requirements of creating a standard parts library.
Pro/E's parametric design concept and family table function Pro/E is the CAD/CAE/CAM software researched and developed by American Parametric Technology Company. Since its development in 1988, it has undergone more than 20 revisions and has become a representative of today. One of the CAD/CAM software. The software is famous for its advanced technology based on feature modeling, parameterized driving, single database, 2D and 3D full dynamic correlation, and has become the mainstream of today's 3D CAD software development. Pro/E is an all-round 3D product development software that combines parts design, product portfolio, mold development, NC machining, sheet metal design, foundry design, automatic measurement, mechanism simulation, stress analysis, product database management, etc. Application modules, each with its own independent functionality, but dynamically associated with each other.
Pro/E came out with the idea of ​​parametric design since 1988, bringing the third technological revolution of CAD technology. The parametric design idea is a distinctive feature that distinguishes it from other 3D CAD software. The basic concept of parametric design The so-called parameterization is to use mathematical operations to establish the relationship between the various dimensions of the model, making it an arbitrarily adjustable parameter. When a certain size parameter value is changed, all the dimensions associated with it are automatically changed, and the function of modifying and controlling the geometry by adjusting the parameters is realized.
Parametric design technology is an important branch of CAD technology. Its theoretical basis is variable geometry, so it is also called variable design, and can also be simply understood as size drive. The so-called parametric design is that the structural form of the product is determined in the design. It needs to determine the structural parameters of a certain structural form of the product according to certain specific conditions and specific parameters, thereby designing products with different specifications. The essence is to create new specifications for products of uniform structure by modifying the size. Using a computer for parametric CAD design, you only need to input several key parameters of the mechanical parts on the computer, and the engineering drawings will be generated accurately and automatically.
The basic process of parametric design is: creating the original graphics y to determine the drawing parameters y using professional knowledge to determine the relationship between the original graphical parameters and specific structural parameters y to generate design drawings and related documents. The entire process requires a database and database management system to store and manage various data and graphics.
Pro/E's FamilyTable functional parametric design is the most basic design idea of ​​Pro/E, and the family table is a model of Pro/E parametric design. With this feature, for a highly repetitive, similarly similar part, use a generic piece (GenericPart) and a family table to represent countless similar parts. To make changes or create new parts, modify the parts list or add new data. Pro/E will automatically modify and generate the model under the driving of a single database.
Establishing the parameter relationship In order to realize the change of the number of bolt holes, all the bolt holes are evenly distributed on the circumference. It is necessary to use the parameterized design function of Pro/ENGI-NEER to establish a certain relationship between the angle of the bolt hole array and the number of bolt holes. Relationship, ie / bolt hole angle = 360 / bolt hole number 0.
Creating family tables Because flange standard parts are divided into different nominal pressure levels, each pressure level has a variety of nominal diameter specifications. Therefore, when establishing a family table, it should be divided into two layers. The first layer has different pressure levels, and the second layer is divided into different nominal diameter specifications for each pressure level.
Conclusion Based on the analysis and comparison of the functional differences between AutoCAD and Pro/E, this paper proposes a method to establish an enterprise standard parts library by using the Pro/E family table function.
Using this method, you only need to create a generic part model for each standard piece, and then build the corresponding family table with the size data of the part in the enterprise standard, and then build the parameter database of the part. When used in the future design, the corresponding standard part model can be automatically generated by the software simply by selecting the required specifications from the part table of the part. This avoids the tedious and repetitive work of establishing different standard parts models, greatly improves the design efficiency, and also facilitates the standardization of the design products; not only can fully improve the use efficiency of the Pro/E software, but also can reduce the designer's drawing. The amount of work gives them more time and energy to carry out creative work on product design.
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