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Research on 3D parametric part library driven by UG generation table

this paper expounds the methods and steps of 3D parametric part library driven by UG generation table, and discusses in detail how to establish parametric model, determine design variables, assign design variables to model, and set up and electronic table with an example. Practice has proved that it is expected to reach 113.7 billion US dollars. Using this method, we can easily and quickly establish the three-dimensional parametric model library of parts, so as to realize the serial design of parts and greatly improve the design efficiency

parts with similar shapes but different sizes are often encountered in design, such as serialized product parts, commonly used standard parts, etc. At present, the two-dimensional design of these parts is relatively mature. However, with the development of cad/cam technology, the design and manufacturing of products have a new development, that is, the design steps from three-dimensional to two-dimensional, that is, first establish a three-dimensional model, and then automatically generate two-dimensional engineering drawings, or use three-dimensional part models to directly generate NC code, so as to realize drawing free processing and save time and cost. Therefore, the establishment of three-dimensional parametric model of parts is particularly important. It will make it possible to serialize the structural design of the product with an annular groove on the top of the cylinder, greatly shorten the structural design cycle, and reduce the amount of work brought to engineers by the size change of parts

I. principle of establishing table driven part model library

in the process of product serialization design, in order to speed up the product design process and reduce repetitive labor, a three-dimensional model library of parts with the same structure and shape but different sizes should be established, such as screws, bolts, nuts, washers, seals, lubricants, bearings and other standard parts. Although UG provides many secondary development tools (such as ug/open grip, ug/open API, ug/open, etc.), using secondary development tools requires designers to have relatively high technology, which is difficult for ordinary designers to complete. The table driven technology provided by UG can also be used to create 3D model libraries of standard parts, general parts and product seriation design

after establishing the 3D parametric model, set the design variables and assign them to the model, then create an external spreadsheet containing these variables and link the spreadsheet to the current model. Because the variables in the spreadsheet are referenced by the part size of the current drawing file, this table can be used to change the size of the parts in the current drawing file, so users can control these parameters outside. Our technicians also introduce the spreadsheet to modify the parts in detail, avoiding the loss caused by having to modify a large number of model parameters due to design changes, And with one model, many parts of the same structure can be expressed

2. Establish a three-dimensional parametric model of parts based on table drive

1 Analyze part features

in order to efficiently create a table driven part, the part must be carefully analyzed before design. First, form a general idea about the modeling of the part as a whole, and clarify what features need to be created in the design part and the order of creating these features; At the same time, we also need to pay attention to the internal relationship of various features to be created and their respective characteristics. Finally, it is clear that the part needs several parameters to drive

in order to realize the parametric design of three-dimensional model, we must first carry out dimensional constraints and geometric constraints on the parts, so as to determine the unique shape of the parts. As shown in Figure 1, ------- Associate Professor Huang Shixin of Jianxing University of science and technology, parts need 8 dimensional constraints and some geometric constraints. See Figure 1 for dimensional constraints. Geometric constraints include: four lines in the top view are tangent to adjacent arcs respectively; Three circles or arcs with a diameter of 25mm, 40mm and a radius of 28mm have the same center; An arc with a radius of 15mm and a circle with a diameter of 16mm have the same center; The center line of two circles with a diameter of 16mm is horizontal. Through the establishment of the above dimensional constraints and geometric constraints, the uniqueness of the part is guaranteed

2. Establish part model

based on the analysis of parts, according to the respective characteristics of parts, create various features required by the three-dimensional parametric model, including geometric features and auxiliary features, and completely constrain the three-dimensional model of parts with all the constraints analyzed above

3. Create and assign design variables

ug provides the function of establishing an association between the driving dimension and the model of the part through expressions. Before establishing the table drive, the determined design variables should be assigned to the corresponding dimensions through the rename expression, as shown in Figure 2 and figure 3. In UG, the constraint size is re carried out, so the allocation of design variables is completed

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Figure 1 dimensional constraints of parts

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Figure 2 allocation of design variables

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Figure 3 rename expression

4. Establish table drive

in UG, the series dimensions of a part can be completely established in the spreadsheet to form a part database. This is very convenient for the management and expansion of this database. Specifically, one or some data in the table can be modified at will, a new set of part data can be added, design variables can be added, and finally the same can be used A three-dimensional model of a series of parts of a solid model

the creation steps of the spreadsheet in UG are as follows:

1) click the menu "tools → expression" to rename and modify the parameter expression, as shown in Figure 2

2) click "tools → part families" in the menu, and the "part families" dialog as shown in Figure 4 will pop up

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