Summary of modern manufacturing technology of the

2022-07-26
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The rapid development of mold manufacturing technology has become an important part of modern manufacturing technology. For example, cad/cam technology, laser rapid prototyping technology, precision forming technology, ultra precision machining technology, dynamic simulation technology of flow, cooling and heat transfer process using finite element method and boundary element method in mold design, CIMS technology of mold, DNM technology and numerical control technology of mold under development almost cover all modern manufacturing technologies

modern mold manufacturing technology is developing in the direction of accelerating information driven, improving manufacturing flexibility, agile manufacturing and systematic integration

I. high speed milling: the third generation mold making technology

high speed milling not only has high processing speed and good machining accuracy and surface quality, but also has low temperature rise (the workpiece is only increased by 3 ℃) and small thermal deformation compared with traditional cutting, so it is suitable for processing temperature and thermal deformation sensitive materials (such as magnesium alloys); Due to the small cutting force, it is suitable for machining thin-walled and poor rigidity parts; A series of advantages such as hard material (HRC60) machining can be realized by reasonably selecting cutting tools and cutting parameters. Therefore, high-speed milling technology is still a hot topic at present. It has developed to a higher agile, intelligent and integrated direction, and has become the third generation of molding technology

II. EDM milling and green product technology

from the perspective of foreign EDM machine tools, the performance, process index, intelligence and automation have reached a very high level. At present, the new trend in foreign countries is to carry out the research and development of EDM milling technology (EDM), which is a new technology to replace the traditional cavity machining with formed electrodes, It uses high-speed rotating simple tubular electrodes for three-dimensional or two-dimensional contour machining (like NC milling), so it is no longer necessary to manufacture complex shaped electrodes, which is obviously a major development in the field of EDM

recently, Mitsubishi Corporation of Japan launched edscan8e EDM machine tool, which has made new progress. This machine can automatically compensate electrode loss. The special cam system developed for this machine on Windows95 can be linked with general CAD such as AutoCAD, and can carry out precision measurement to ensure high-precision machining. In order to confirm whether the machining shape is abnormal or incomplete, the cam system can also realize simulation machining

with the progress of EDM technology, people pay more and more attention to the safety and protection technology of EDM. Many EDM machine tools consider the safety protection technology. At present, the European community has stipulated that machine tools without CE mark cannot enter the European Community market. At the same time, the international market is paying more and more attention to the requirements of safety protection technology. At present, the main problem of EDM machine tools is radiation disturbance, because it has a great impact on safety and environmental protection. Under the situation that the international market pays more and more attention to green products, the green product technology of EDM machine tools, as the leading equipment for mold processing, will be a difficult problem that must be solved in the future

III. new generation mold cad/cam software technology

at present, the mold software developed by some universities and scientific research institutes in Britain, the United States, Germany and other countries has the characteristics of intelligence, integration and mold manufacturability evaluation of the new generation mold cad/cam software

the new generation of mold software should be based on a large amount of knowledge summarized from the mold design practice. These knowledge have been systematized and scientifically sorted out, stored in the engineering knowledge base in a specific form and can be easily called by the mold. With the support of intelligent software, mold CAD is no longer an imitation of traditional design and calculation methods, but under the guidance of advanced design theory, making full use of the rich knowledge and successful experience of experts in this field, the design results must be reasonable and progressiveness

the new generation of mold software designs the mold structure with three-dimensional thought and intuitive feeling. The generated three-dimensional structure information can be easily used for mold manufacturability evaluation and NC machining. This requires that the mold software achieve a fairly perfect degree and a high level of integration in three-dimensional parametric feature modeling, molding process simulation, numerical control machining process simulation, information exchange, organization and management. To measure the degree of software integration, we should not only see whether the functional modules are complete, but also whether these functional modules share the same data model and form a global dynamic database in a unified way, so as to realize the comprehensive management and sharing of information, so as to support the whole process of mold design, manufacturing, assembly, inspection, testing and production

the function of mold manufacturability evaluation is very important in the new generation of mold software. It is necessary to screen multiple schemes, evaluate the rationality and economy in the process of mold design, and provide modification basis for mold designers

in the new generation of mold software, manufacturability evaluation mainly includes mold design and manufacturing cost estimation, mold assembly evaluation, mold part manufacturing process evaluation, mold structure and formability evaluation, etc. The new generation software should also have assembly oriented function, because the function of the mold can only be reflected through its assembly structure. After adopting the assembly oriented design method, the mold assembly is no longer a simple assembly of parts one by one. Its data structure can not only describe the functions of the mold, but also define the assembly features of the relationship between the mold parts, so as to realize the correlation of the parts, so as to effectively ensure the quality of the mold

IV. advanced rapid tooling manufacturing technology

1. The rapid development of Laser Rapid Prototyping Technology (RPM) has reached the international level in China, and has gradually realized commercialization. The world's commercialized rapid prototyping processes mainly include SLA (stereolithography), LOM (layered split manufacturing), SLS (selective laser sintering) and 3d-p (3D printing)

Tsinghua University first introduced sla250 (stereolithography or photosensitive resin laser curing) equipment and technology from American 3D company and carried out development and research. After several years of efforts, it has improved and launched m-rpms-type multi-functional rapid prototyping manufacturing system (with layered solid manufacturing SSM and melt extrusion MEM), which is the only system in the world with two rapid prototyping processes (national patent) with independent intellectual property rights in China, It has good performance price ratio. 2. Dieless multi-point forming technology is another advanced manufacturing technology that uses highly adjustable punch groups to replace traditional dies for sheet metal surface forming. The dieless multi-point forming system takes cad/cam/cat technology as the main means to realize the automatic forming of three-dimensional surface quickly and economically. Jilin University of technology has undertaken the national key science and technology project on dieless forming, and has independently designed and manufactured the internationally leading dieless multi-point forming equipment

compared with the Massachusetts Institute of technology in the United States, Tokyo University in Japan and Tokyo University of technology in Japan, this technology in China is in a leading position in theoretical research and practical application. At present, it is developing towards popularization and application. 3. The resin stamping die has been successfully applied in the trial production of domestic cars for the first time. FAW mold manufacturing Co., Ltd. has designed and manufactured 12 sets of resin molds for the modification and trial production of the new xiaohongqi car. These 12 sets of molds are large-scale drawing molds such as trunk, engine hood, front, rear, left and right fenders, etc. 3. The machine can also be used for steel tube bending experiments. The main feature is that the mold surface is based on the main model processed by cad/cam, and is cast and formed with high-strength resin refined by Ciba, The clearance between male and female dies is accurately controlled by imported special wax sheets. The dimensional accuracy of the dies is high, the manufacturing cycle can be shortened by one half to two thirds, and the manufacturing cost can be saved by about 10million yuan (12 sets of dies). It opens up a new way for the trial production and small batch production of cars in China, which is the first in China. Relevant experts of Ciba Specialty Chemicals in Switzerland believe that it can reach the international level in the 1990s

v. field mold inspection technology

with the development of precision molds, the requirements for measurement are becoming higher and higher. The precision CMM has been limited by the environment for a long time, and is rarely used in the production site. The new generation of three coordinate measuring machines basically have the characteristics of temperature compensation, anti vibration materials, improved dust prevention measures, improved environmental adaptability and operational reliability, so that they can be easily installed in the workshop for use, so as to realize the field measurement

VI. mold surface engineering technology of mirror polishing

mold polishing technology is an important part of mold surface engineering and an important post-treatment process in the mold manufacturing process. It has a correlation with the cutting method and rolling direction of samples. At present, domestic polishing equipment, abrasives and processes for polishing molds to ra0.05 M can basically meet the needs, while mirror polishing equipment, abrasives and processes to be polished to Ra0.025 m are still in the exploratory stage. With the large-scale application of mirror injection mold in production, mold polishing technology has become a key issue in mold production. As there are still some problems in domestic polishing technology and materials, for example, the injection mold for the lens of point and shoot cameras, CD, VCD discs and injection molds with high transparency requirements for tools still rely on imports

it is worth noting that the mold surface polishing is not only affected by the polishing equipment and process technology, but also by the specularity of the mold material, which has not attracted enough attention, that is, the polishing itself is restricted by the mold material. For example, when 45# carbon steel is used as the injection mold, when polished to Ra0.2 m, obvious defects can be seen by the naked eye. If it continues to be thrown, it can only increase the brightness, and there is no hope to improve the roughness. Therefore, at present, China has increased its efforts in technological innovation. In the production of mirror mold, imported mold materials are often used, such as Sweden's yishengbai 136, Japan's Datong pd555, and so on, to obtain a satisfactory mirror degree

the mirror mold material is not only a problem of chemical composition, but also a series of advanced processes such as vacuum degassing, argon protection ingot, vertical continuous casting and rolling, and flexible forging are required during smelting, so that the mirror mold steel has a series of advantages, such as less internal defects, fine particle size of impurities, high dispersion, fine grain size of metal, good uniformity and so on, so as to meet the requirements of polished to mirror mold steel

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