Precision prototyping technology is commonly used in the rapid manufacturing industry, which includes precision casting (wet film forming, rigid casting, core forming), precision forging (cold, wet forming, blanking), precision thermoplastic prototyping, precision welding, and cutting. These technologies are widely used in the production of key parts of automobiles, washing machines, home appliances, electrical appliances, etc., such as the manufacture of air ducts, steering knuckles, precision connecting rods and complex contour parts (such as automobile bodies).
For the processing of mechanical components, the blank is first produced. After cutting, grinding and other processes, products that meet the design requirements can be obtained. The traditional processing methods from blank to product, the consumption of materials, energy, and time are very large, and a large amount of waste is generated. Precision prototyping technology can greatly change this situation. The use of physical and chemical changes such as melting, crystallization, plastic deformation, diffusion, and other changes, the mechanical components are formed according to predetermined design requirements, with the aim of bringing the shaped article to or near the final desired shape or size – this is precision prototyping technology. It is a combination of modern technology (computer technology, new materials technology, precision CNC machining, and measurement technology) and traditional prototyping technology (casting, forging, welding, cutting, etc.). It can not only improve the utilization of materials, reduce pollution, but also make the component materials obtain the chemical composition and organizational structure that are difficult to obtain by traditional methods, thereby improving the quality and performance of the products. Precision prototyping is a key technology for the production of high-tech products such as computers, electronics, communications, aerospace, instrumentation, and other products.
Precision Prototyping Technology Development Trend
At present, the precision prototyping of some small and medium-sized parts has been achieved without cutting or machining allowance. The International Machining Technology Association predicts that the combination of precision forming and grinding at the beginning of the next century will replace the cutting of most small and medium-sized parts.
Precision prototyping technology has been widely used in industrialized countries. Through the cooperation with advanced CNC prototyping process equipment and testing methods, prototype manufacturing units of different grades have been formed, and the traditional prototyping process and equipment have been replaced. In the coming period, China will use the automotive industry as the main application object, combine the typical parts to develop precision forming technology, and form a complete set of technologies for production. The first point is to increase the proportion of local production of car production equipment, and the second is to increase the proportion of localization of car parts.
Application of Digital Precision Plastic Prototyping Technology
Digital precision prototyping mainly includes digital precision plastic forming and digital precision casting. Digital precision plastic machining technology is a technical system that integrates digital technology in the whole process of plastic prototype and based on system engineering to achieve high quality, high efficiency, low consumption, and clean production. The research includes: establishing a digital model based on computer graphics, interacting with different requirements with a unified data exchange standard and engineering database, realizing model and information sharing; product design based on precision plastic forming Based on the digital model, to go the product performance analysis; digital manufacturing of products including process and digitalization of manufacturing equipment.
At present, the simulation of precision plastic forming process has entered a practical stage in industrialized countries. The analysis of the finite element program AL PID (Analysis of Large Plastic Incremental Deformation) developed by the American Batllle Research Laboratory under the auspices of the US military is the beginning of plastic forming numerical simulation technology. In the design and manufacture of engine cover molds in the United States, it is required to pass the computer simulation test after the design is completed, in order to put into the manufacture of the test soft mold. Biba et al. of Quntor, Russia, used numerical simulation methods to optimize the forging die, which improved the life of the die and improved the accuracy of the parts. The specific method is to use numerical simulation results to optimize mold parameters, such as fillet radius, reduce stress concentration, and use shrink rings and inserts.
General Motors Corporation of the United States has developed a digital development platform and system for stamping dies. The system uses a three-dimensional design platform to parameterize and variable the mold and develops the mold surface based on the expert system and manufacturability design to make the traditional technological mold development process was transformed into a science-based digital development. The system integrates GM’s decades of stamping process experience and specifications and uses numerical simulation software to perform part formability and quality analysis and modification to quantitatively predict and solve problems in mold development. Formed the mold design, mold manufacturing, trial mold, stamping production in the digital environment, the accuracy of formability prediction is 90% to 95%, overcoming the limitations of the mold developer’s personal experience, the general mold test mode 1 to 2 days It can be done. Taking the stamping parts such as the military Hummer body as an example, the digital mold development system is used to reduce the mold development cycle by 80% and the mold cost by 50%. In addition, General Motors has combined optimization techniques with numerical simulation techniques to achieve numerical simulation-based optimization.
Shim from Yeungnan University in South Korea used the sensitivity method to determine the shape of the initial sheet. The shape sensitivity was determined by Pam2Stamp finite element simulation, and the design of the stretch forming process for any shape of sheet metal parts could be optimized. The Canadian Forming (FTI) company’s CA TIA method for sheet metal design simulation unifies design and analysis in one program. By simply changing the geometry, material properties, or sheet thickness, computer-aided optimization is used, and the simulation results serve as an early warning system.
In recent years, CNC machining China has carried out some research on digital precision forming technology, but lack of systematic integration research, cannot achieve single-item promotion integration, partially drive the whole, technical advantages cannot be transformed into product advantages, the whole industry precision forming technology. There is no qualitative jump in level. Therefore, the research of domestic precision forming technology should strengthen independent innovation and break through key technologies. Such as product information modeling technology, process simulation, and optimization technology, mold design intelligent generation technology, etc., to achieve integrated integration of precision forming technology, improve process design level, further realize the digital design and manufacturing integration, shorten the product development cycle, reduce manufacturing costs. At the same time, the application of results should be strengthened to improve the level of proto manufacturing technology in the whole industry.