Development and Application of CAD 3D Standard Parts Library for Punching Dies

The study of stamping dies CAD/CAE/CAM integrated system plays an important role in the development of the manufacturing industry. Due to the large number of repetitive labor in engineering design, complicated engineering calculations have become common problems in various engineering designs. In order to make better use of CAD software, it is necessary to standardize parts, generalize parts, and parameterize typical parts. Practice has proved that 3D design is an inevitable trend in the development of CAD applications, and in order to more effectively use the CAD system The role must be secondary development of the system to achieve the professionalization and customization of CAD/CAE/CAM systems. CAA is a module in the CATIA software package, and is a software tool provided by IBM for secondary development of CATIA. CAA Languages ​​are used to create programs that are similar to FORTRAN. Integration with CATIA systems Because CAA and CATIA are tightly integrated, CAA programs can be used to accomplish various interactions with CATIA.

1 Establishment of three-dimensional standard parts library for punching die

The advantage of program parametric modeling is that it is convenient and flexible. It has low requirements on the system. It is suitable for parts with simple structure and easy programming. For example, direct system modeling of pins, the establishment of models is easier, but it requires a lot of modeling work. Structures that are complex but stable, with few possible changes, such as lateral punches, are built using direct system modeling. Parameterized system modeling can use the system's parameterization functions to modify the expressions of the model that is created. The realization of parameterization is applicable to parts that change more freely, such as punches and mold clamps.
Therefore, in conjunction with specific requirements, to achieve as many standard parts as possible into the standard parts library, the system's modeling idea is to analyze different standard parts, decide which one to use, and adopt different methods for different methods. The implementation steps of simple and variable parts adopt parametric modeling of the program, complex and less variable parts adopt direct system modeling, and complex and variable parts adopt parametric system modeling. Different modeling approaches are uniformly managed under the CAA program and integrated in CATIA. In the environment.
1. 1 Implementation method of punching die three-dimensional standard parts library According to the analysis of the method of developing the three-dimensional standard parts library in front, combined with specific requirements, the construction process of the parameterized standard parts library in this system is to analyze different standard parts. Deciding which modeling method to use, and using different implementation steps for different methods. This section mainly introduces the parametric system modeling method.
The parametric modeling workflow for the program is shown in Figure 1. The workflow for direct system modeling is shown in Figure 2.


The parameterized standard part library construction process of this system parameterized system modeling method is divided into the following steps:
1) Establish parametric solid model of standard parts The process of establishing parametric models is mainly realized by using the functions of CATIA. The model driving technology is a key technology of model parameterization. Only the change in size occurs before and after the parts are driven, and the topology relationship does not change. In the part model, including part entities and their dimensions, drive variables, and reference variables, etc., correspond to the three dimensions of CATIA. 1 The numerical form: the size in the form of numerical values; 2 variable name form: one for each size Codes are marked with d0,d1,...dn. Representation; 3 equation form: such as d3 = d1,
The model entity determines the topological relationship of the part, the constant size is the constant constraint in the model, the driving variable is a variable constraint with a certain value, and the reference variable is the combination of the driving variables. The model-driven only directly changes the value of the driving variable. The reference variable is automatically changed according to the change of the driving variable. The modeling software recalculates according to the modeling process of the model solid and the new variable value to obtain the new part.
2) Reading the relevant parameter values ​​The parameter data organization means that according to the characteristics of the standard part parameters, a reasonable data structure is developed to describe the parameter data of the standard parts. The parameter data can be divided into two categories: 1 main parameter (single parameter) There is only one decisive parameter in the parameter data of the standard part. When the main parameter is determined, the corresponding other parameters are all determined. 2 The main parameter, the sub-parameters (double-parameters): Except for these parts In addition to a main parameter, there is a minor main parameter group corresponding to the main parameter series. After the main parameter is determined, the minor main parameter can only determine the range of one value, and only after the value of the minor main parameter is determined. All component parameters can be determined.
3) Alignment model for assembly All models are stored in one path to form a library file. The program should provide a function to automatically search for the required parts, and adjust it to install in the appropriate location.
4) Output Expression File Since the CATIA system has the following convention: to adjust the part, the expression is added to the original expression "single quotation marks" and a numeric serial number to distinguish, so change the expression to automatically extract this number 5) Press Related parameters modify the expression to modify the model according to the new expression. The workflow of the parametric system modeling is shown in Figure 3.

1.2 The function of the management interface of the system integration standard part is to implement the user's selection of the type of standard parts required. Therefore, it is necessary to display the series, specifications and parameters of the corresponding standard parts according to the user's selection in the interface. And the meaning of each parameter, for the user to confirm. Integrate all the functions together, thus forming a powerful professional library of functions.
The main application interface lists the buttons for the names of all the standard parts. Click the button to enter the next level of the dialog box. At this time, the related information of the corresponding standard parts and related information of each parameter are displayed. Then the user is prompted according to the specific situation. Enter the relevant parameters or select the appropriate button.
In the CAA language, powerful human-computer interaction statements are provided. The user can use the CAA program to provide the function of dialogue with the system and complete the interactive operation. Therefore, these management interfaces can be implemented using the standard parts library operation interface using the CAA program. VC The application program interface has its advantages, standard parts of the relevant information using VC program to achieve.
For graphics editing and solid modeling, the CAA program is incapable. Therefore, the system uses the CAA program to organize the data, make the interface, and perform data processing. For solid modeling, it is performed in the CATIA system. Can play their own advantages, the three systems integration, the formation of a friendly interface, powerful die-cutting computer aided design system.
2 Application examples of punching die three-dimensional standard parts library Take the product digital die of the crossbeam reinforcement plate on the left and right side of the car console as an example, the material thickness is 1mm.
The entire process is for the left and right pieces of the same mold manufacturing, this example is a 4/4 punching process, due to the hole position and the accuracy of the hole diameter, the stamping direction is adjusted so that the five mounting holes are flushed out, the two mounting holes on the slope The need to lift to achieve, therefore, the structure of the mold for most of the composition of: 1 hanging punching device, the use of standard components UCSMC50 Japan 30; 2 lower mold assembly, lower mold base in the form of casting, directly on it Cast the positioning profile, install the die insert and waste box at the punching position, install the guide post and guide slide at the guide position (provided by the standard parts library), 3 press plate assembly, use the base casting, and inserts Form, between the pressure plate and the upper mold base guided by the guide slide, and connected with the side pin, elastic unloading components using spring preload assembly (provided by the standard parts library); 4 mold base assembly, in cast form, in its Guide guides and guiding plates are installed on the guiding legs, and pads, punches, mold clamps and screws, and pins are provided on the bosses (provided by the standard parts library).
First, the design of the positioning surface and positioning body. The product digital model is saved as a Part file for the lower mold part design. Using the free surface modeling function of CATIA, the product number model surface is postponed and cut according to the positioning needs, and then performed. Stitching. Use the Solid Modeling function to give the cuboid where the locator needs the size in the desired position. Cut the upper part of the cuboid with the sutured surface. The desired locator body design is completed. Then the CATIA entity modeling function and features. The modeling function designed the basic shape of the lower mold solid model, as shown in Fig. 4 and 5.
The lower die assembly is composed of a lower die body and some standard parts. It can directly use the standard parts library in the die cutting CAD system to directly generate a solid model for assembly. If the guide slide is installed at the guide position, the current work coordinate is firstly transformed. To the installation location, you can then call the standard parts you need to install in the standard parts library.
Open the File--.Execute CATIA/Open-CAA system interface for selecting the type of standard parts, as shown in Figure 5. Click on the guide slide icon and enter the parameters of the standard part selection system interface, as shown in Figure 6.


Click OK, the input parameter dialog box appears, as shown in Figure 7, enter the length of 150, wide l00, click OK, complete the standard component guide skateboard installation.


The installation process of other standard parts is consistent with the installation process of skid-slide. The physical model of the lower die assembly after loading the standard parts is shown in Figure 8.


3 Conclusions From the digital product definition to the application of digital assembly technology, mold design is gradually moving from 2D-assisted design to the digital era of 3D mainstream design. Nowadays, various specialized 3D design softwares are becoming more mature and diversified. Units use national standards. With enterprise standards, and the use of specific standards for some units, the widespread use of general-purpose parts/standard parts, the development of standard parts libraries has become a key goal of our research and implementation of digital design and manufacturing technology applications. More intelligent, and can be integrated with full-text databases such as national standards, national military standards, industry standards, etc., to enable intercommunication of two-dimensional information and three-dimensional information, query of nonparametric attributes of standard parts, etc. The punching die three-dimensional standard parts developed in this paper The library is just an important part of the mold CAD. The mold CAD should be developed in the direction of intelligence, and the mold knowledge base and typical structure library should be established, and the computer aided design system of the mold should be gradually improved.

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