In China, most of the molding process and mold design of automobile panels still mainly rely on the experience of designers, relying on some qualitative theoretical analysis and empirical data. Not only is the design time long and cannot keep up with the pace of the international market, but also because the influence of various parameters on stamping is difficult to determine, it must be repeatedly modified in the trial phase after the design, which consumes a lot of material and financial resources, and even many large molds still need to be imported . Group companies like FAW also rely on imported advanced CAD/CAM systems and equipment to produce high-quality and high-precision panel molds. The domestic specialized panel mold CAD/CAM system is basically being researched and tried in colleges and universities, and no forming system has appeared yet. Universities such as Huazhong University of Science and Technology, Jilin University of Technology, and Shanghai Jiaotong University that have made certain achievements in this regard are still in their infancy.
Looking at the development history of the world’s automobile industry, it can be seen that automobiles have gradually developed and improved along / chassis 0y/engine 0y/body 0. From the perspective of automobile production practices at home and abroad, chassis and engine production technologies are becoming more and more mature. The development of vehicle production capacity depends on the body production capacity, and the upgrading of automobiles also depends on the body to a large extent. When the basic models reach saturation, only by relying on body modification or modification can the market be opened up. Modern automobile body styling technology is gradually becoming mature. The body styling fully considers the requirements of aerodynamics and aesthetics, giving the car a strong sense of the times, and its surface is required to be smooth and beautiful.
Automobile covering parts refer to the surface parts and internal parts of the thin steel plate profiled bodies that cover the engine, the chassis, the cab and the car body, including the outer cover, the inner cover and the support part. Compared with general stamping parts, covering parts have thin materials, complex shapes, mostly spatial curved surfaces, and high structural dimensions and surface quality. Moreover, for the beauty and rigidity of the car body, it is necessary to design ridges, ribs, convex hulls and other shapes on the cover, which further enhances the complexity of the profile. At the same time, the cover part is a nonlinear, elastoplastic, and large deformation process during the stamping process. Only with the aid of CAD/CAM technology can we understand the material deformation and flow of the blank during the stamping process, and can prevent ripples, wrinkles, and wrinkles on the cover surface. Process defects such as dents, and serious process problems such as tearing and springback. In fact, CAD/CAM technology has become an important guarantee for the production of beautiful, cheap, and high-quality cars in developed countries. In the entire cycle of model design, mold design and debugging, and manufacturing, mold design and manufacturing account for about 2/3 of the time. Therefore, the application of CAD/CAE/CAM technology for cover molds has played a key role in shortening the development cycle.
Cover mold CAD/CAM integration program At present, many large-scale foreign CAD/CAM systems have been introduced in China. Aiming at the development of the domestic automobile industry, we have made extensive investigations and studies, and made a general plan for the CAD/CAM integration scheme of automobile panel molds. The topological relationship is shown in the figure. The system mainly relies on general CAD/CAM software to develop a complete set of automotive panel mould CAD/CAM integrated system, and design several functional modules in the system.
The discrete point data of the main model of the data acquisition cover is usually measured by a three-coordinate measuring instrument, and the CAD software reads these discrete point data through the interface program. However, because the amount of data is too large for practical application, it is often necessary to simplify the node to greatly reduce the amount of data, so as to achieve the purpose of practical application. Then in the AutoCAD environment, the simplified discrete point data is converted into a visual surface wireframe.
Curved smooth coverings generally require surface smoothing, which can reduce the air resistance in the driving of the car, but also meet the user’s requirements for the beautiful and generous viewing effect of the car body. Before surface fitting, each type value point must be smoothed, so as to fit a high-quality panel surface and lay the foundation for subsequent work. Generally, CAD software does not have a module for smoothing discrete point data. Even with such a module, it is difficult to achieve satisfactory results. Therefore, in order to fit a high-quality smooth cover surface model, the collected discrete point data must be smoothed.
Concluding remarks Auto covering parts are the main parts that make up the car body, most of which are spatial curved shapes with large outline dimensions, so the development of covering parts molds is quite difficult. In China, most of the work of automobile covering mold design mainly relies on some qualitative theoretical analysis and empirical data of the designer. Not only the design time is long, but the influence of various parameters on the stamping forming is difficult to determine. After the design, it must be repeated in the trial phase. Modifications consume a lot of material and financial resources. Most of the large-scale CAD/CAM systems introduced in China are general-purpose software. In the process of designing and manufacturing panel molds, they often cannot meet the actual needs of production. Therefore, feature-based product modeling and systematic secondary development in the field of mold design and manufacturing can take advantage of the powerful functions of existing commodity software and save a lot of time in the development of grassroots software, thereby establishing a set of mold design suitable for domestic automotive panels A complete CAD/CAM integrated system for manufacturing, which can promote the development of the automotive industry efficiently, quickly and steadily.
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