Wednesday, April 8, 2020

Several ways to improve the metallurgical quality of die steel in China

With the development of science and technology in recent years, the application of technology in the mold industry is constantly improving. Mold companies have been focusing on the research of ways to improve the metallurgical quality of mold steel. After years of hard work and exploration, at present, the main metallurgical production departments at home and abroad are committed to improving the quality of mold steel metallurgy mainly in the following aspects:
Several ways to improve the metallurgical quality of die steel in China

1. Smelting quality For high-quality mold steels, domestic and foreign extensive use of external refining, vacuum treatment, vacuum smelting, powder spraying, electroslag remelting and other processes to reduce harmful elements, oxygen, hydrogen and inclusions in steel Content, fine-tuning the chemical composition and pouring temperature. Electroslag remelting can also effectively improve the low-power structure and density of steel, and improve the isotropy of mold steel. Tests by some domestic manufacturers have shown that the transverse impact toughness value of 4Cr5MoSiV1 steel produced by electric arc furnace is only 31% of the longitudinal direction, and the transverse impact toughness value of 4Cr5MoSiV1 steel after electroslag remelting can be equivalent to 70% of the longitudinal direction Increase more than 1 times. For mold steel with special requirements, powder high-speed steel and powder high-alloy mold steel produced by powder metallurgy process can better improve the structure and performance of steel.

2. On the basis of guaranteeing a certain forging ratio, the forging rolling process adopts upsetting and drawing long forging and cross rolling processes as much as possible to improve the isotropy of the mold material. In order to reduce the processing margin and improve the utilization rate of materials, precision forging machines, fast forging hydraulic presses, and high-precision continuous rolling machines are widely used to provide high-precision steel products to meet the needs of mold manufacturing.

3. Heat treatment and heat treatment of forged and rolled materials should use controlled atmosphere or vacuum heat treatment to avoid oxidative decarburization. Some plastic mold steels and hot work mold steels should be pre-hardened by the metallurgy department. For some high-demand hot work die materials, the metallurgical department should pre-organize and refine the structure to eliminate coarse carbides and chain-like carbides in the steel to obtain a fine and uniformly distributed carbide structure to further improve the steel Various properties, especially isotropy. According to some foreign reports, some hot work die steels are electroslag remelted—multidirectional forging (rolling) —structure refinement treatment to produce high quality and isotropic die steels, the transverse impact toughness value of which can be comparable More than 90% of the vertical. Many steel mills have named trade names for the steel produced by this process, such as ISODISC of Bole Steel in Austria; ISOTROPY of Hitachi Metals in Japan; MICROFINE of Japan High Frequency Steel Co., Ltd., etc. this work. In addition, considering the metallurgical quality of each part of the steel, when manufacturing the mold, care should be taken to select the main working surface of the mold (such as the cavity or blade) to be close to the surface of the steel; because the surface of the steel is generally a clean part of the steel The core of the steel is the area where the low-magnification defects of the steel are concentrated; especially in the large-section Leidenite steel, the eutectic carbide unevenness of the steel in the central part will be 2 to 3 higher than the surface part. Also, the main load bearing direction of the mold can be selected to be consistent with the deformation direction of the steel to reduce the adverse effect of the anisotropy of the steel on the mold.

4. Thermal conductivity Thermal conductivity is also one of the main performance indicators of mold steel, especially some hot work mold steel and plastic mold steel. The mold steel with good thermal conductivity can quickly transfer the heat generated during processing and the heat transferred from the processed workpiece to avoid overheating on the working surface of the mold and improve the working conditions of the mold. For some thermoplastic forming molds and some die casting molds, in order to speed up the production rhythm, it is hoped that the pressed workpieces will be quickly cooled and demolded to improve productivity. In order to solve this problem, sometimes some mold materials with better thermal conductivity than steel are used, such as High strength copper alloy, high strength aluminum alloy, etc.

The focus of fine blanking die technology products and technology development

1. Research on key technologies for design and manufacture of continuous precision die for complex parts

    Continuous fine blanking dies for complex parts is the leading basic technology of fine blanking technology. With this as the leader, research is expected to drive the substantial improvement of fine blanking technology in China. Taking the synchronizer ring, clutch plate, longitudinal composite continuous fine blanking process and continuous fine blanking of complex parts such as molds as breakthroughs, we have studied the key technologies of fine blanking mold design and manufacturing, and realized the rapid improvement of fine blanking mold technology in China. National gaps.
The focus of fine blanking die technology products and technology development

2. Research on life improvement of fine blanking die and related key technologies

    Mold life is a comprehensive reflection of the level of mold materials, small arts and supporting products. Taking the life of fine blanking molds as the leader to launch technical research can not only solve the problem that the long life of fine blanking molds that are urgently needed in China is too low, but also drive mold materials, fine blanking Technological development of processes and supporting tooling and other auxiliary products.

3. Research and development of fine blanking-precision forging composite process technology

    Fine blanking and fine forging are two advanced manufacturing technologies developed in parallel. Fine blanks are too thick and require precision forging. Fine forgings must be fine blanking. The two are closely related and closely related. The basic idea of ​​developing the fine forging-fine blanking composite process is to find the combination of these two processes (such as gear parts with hubs and cam parts with short shafts), and precision forging in China has a long history and the level is already very high It is a good way to improve the overall level of fine blanking technology in China

Development status and main problems of fine blanking die technology

Fine blanking technology has been invented in Europe in the 1920s and has gone through more than 80 years. It is one of the most important precision plastic forming methods for the manufacture of thick plates. It is an economical production of high-volume, high-quality, multi-functional ferrous metals. And non-ferrous metal parts with high technical content and good economic benefits. The fine blanking press completes a stamping process. Through the processing of the special fine blanking die, one or more pieces of high-precision shaped parts that can be directly used for assembly will be manufactured. They have been widely used in electronics, computers, power, and home appliances. , Automotive and aviation. According to incomplete statistics, at present, 40 countries in the world have adopted fine blanking technology, with a total of about 4500 fine blanking machines and about 10,000 parts produced. For example, in a car (car) including gear shift forks, seats and seat belt angle adjusters, planetary gears, brake shoes and steel back, there are nearly 100 kinds of fine blanking parts.
Development status and main problems of fine blanking die technology

China's fine blanking die technology has made great progress during the "Eleventh Five-Year Plan" period, and has achieved a series of scientific research results in fine blanking technology, materials, fine blanking presses, die holders, molds and lubrication. As of the end of 2008, there are nearly 20 provinces and cities in China with professional fine blanking production equipment, more than 80 fine blanking presses (excluding hydraulic formwork), more than 5,000 employees in fine blanking, and about 2000 types of fine blanking parts. And has formed several independent fine blanking die development demonstration base. Metal materials are expanded from non-ferrous metal punching to ferrous metal punching. The punching thickness of low carbon steel, low alloy steel and stainless steel reaches 12mm; the punching thickness of non-ferrous metals such as aluminum alloy and copper alloy reaches 18mm; with the advancement of mold materials and processing methods and the perfection of the spheroidizing process of punched plates With popularization, some harder high-carbon steels, high-alloy steels, and other low-toughness materials such as nickel-based or cobalt-based alloy materials have also begun to be used in the production of fine blanking parts. In addition, the proportion of self-developed progressive compound fine die, transfer die and modular die in domestic fine die has increased significantly. Especially the progressive compound fine die for complex parts of automobile transmission system has basically been localized. The research, development and application of finite element numerical simulation technology for fine blanking forming process, fine blanking die structure optimization technology, fine blanking die intelligent design and knowledge base technology have enhanced and enriched the technical connotation of fine blanking die in China. However, at present, fine blanking companies are generally small in size, dispersed in resources, low in production efficiency, lack of talents and incomplete. Although it has certain development capabilities in the development of fine blanking dies, there is still a lack of experience in the development of complex fine blanking dies, especially fine blanking composite forming dies, and imported dies still account for a large proportion

High-speed development of the precision mold market

Nowadays, there are more and more mold companies, and the requirements for molds in many industries are increasing. Therefore, the development of the precision mold industry is gradually hot. With the vigorous development of the electronic information industry and the information transformation of traditional industries, the plastic mold market has a bright future. The global high-end, precision plastic mold market is in short supply.

     In recent years, China's plastic mold manufacturing level has been greatly improved. The weight of a large set of large plastic molds has reached more than 50t, the precision of precision plastic molds has reached 3cm, and a multi-cavity plastic mold has been able to produce a 7800 cavity The plastic molds and high-speed molds have been able to produce high-speed plastic profile extrusion molds with an extrusion speed of more than 4m / min and main cavity double-cavity co-extrusion molds. With the rapid development of the plastics industry and the continuous improvement in strength and other aspects of general and engineering plastics, the application range of plastic products is also expanding, and the amount of plastic products is also rising. It is understood that the output of China's plastic products in 2012 was close to 60 million tons, and it is still in the process of continuous growth. This shows that domestic demand has a huge driving force for China's plastic mold industry.

Precision mold market

At present, plastic molds account for about 30% of the entire mold industry, and the proportion of mold imports and exports is as high as 50 to 70%. In recent years, China's plastic molds have developed rapidly. The application of plastic products is increasingly widespread, providing a very broad market for plastic molds. The trading market of China's mold industry is very large, and it is still growing at a rate of 15% to 20% every year. This is mainly due to the development of China's auto, household appliances, IT industry, packaging, building materials, daily necessities and other major user industries.

Precision mold market

      Affected by various national policies and the continuous expansion of market space, the development momentum of the automotive, IT industry, packaging and other industries in recent years has been very rapid. Not only has there been a great development in production capacity, but also in the high-end aspects of these industries Great progress, therefore, the above industries have strong mold demand in the three aspects of high school and low end. According to the statistics of relevant industries, the output of China's plastic products in 2012 was close to 60 million tons, and it is still in the process of continuous growth. This shows that domestic demand has a huge driving force for China's mold industry.

      The development degree of a product in the market is affected by many factors. The first is market demand. When this product is needed by the market, there is an opportunity for development. Then there is the quality of the product itself. If the quality and technology of the product can continue to innovate and improve, then the value of the product itself can be made higher, and at the same time, it will be more popular in the market. The development of the plastics industry is inseparable from the mold, then at this time the mold industry needs to continue to develop and innovate to consolidate and perfect its market position, and carry out the rapid development of the mold industry to the end.



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