Mold material technology R & D is facing revolution.
With the development of China's die and mould industry, higher and newer requirements have been put forward for the quantity, quality, variety and performance of die and mould materials, and the market of die and mould materials has been developing rapidly. According to Luo Baihui, executive secretary of the International Association of Mold and Hardware Plastic Industry Suppliers, the range of materials used for dies and moulds is very wide, ranging from ordinary carbon structural steel, alloy structural steel, carbon tool steel, alloy tool steel, high speed tool steel, stainless steel, maraging steel to cemented carbide, refractory alloy, superalloy and non-alloy. Iron and metal can be selected, mainly belonging to the die steel of alloy tool steel. At present, the output of China's alloy tool steel ranks the highest in the world, of which the alloy die steel is about 100 thousand tons. China's die and mould industry consumes 300,000-400,000 tons of die and mould materials annually, including 130,000-150,000 tons of alloy die steel.
Li Guangchao, an expert consultant to the Steels Committee of the International Association of Mold and Hardware Plastic Industry Suppliers, said that at present, the quality of domestic mold steel is relatively low, and a considerable number of high-quality mold steel are required to undergo vacuum refining and electroslag remelting to ensure the high purity, high density and high orientation of the steel. The proportion of die steel for ESR is very small. About 80% of the die steel market is black leather round bar, users get the material after their own forging system, material utilization rate is low, production cycle is long, can not meet the needs of modern die manufacturing industry.
Traditional steel substitution technology
Shenzhen Zhuwei Special Steel Co., Ltd. developed a new type of high-efficiency TS4 mold copper alloy material, hardness can reach HRC38-45 degrees, without heat treatment, production and processing easy, low friction coefficient, and in the alloy with wear-resistant elements, so that the wear resistance of the original wear-resistant copper alloy is further improved, especially suitable for drawing. The need for stretch die. In the cost of mold manufacturing, the cost of material often only accounts for about 20% of the cost of mold, but the competition of the mold industry is the competition of the efficiency of mold use, rather than the low price of mold materials to win, so for the higher requirements of long life mold, the choice of mold materials often needs to be improved. For example, the service life of the drawing die made of Cr12MoV steel with carbide inhomogeneity of 5-6 grade is often less than 10,000 pieces, while the service life of the drawing die made of TS4 copper alloy die can reach 70,000 pieces or more. This is because the TS4 copper alloy mold has good thermal conductivity, which can ensure the uniform temperature distribution of the mold in work, will not cause cracks in the mold due to local high temperature, and will not cause cold welding stripping and wrinkling on the surface of the stretched product. It can shorten the opening time, improve the life of the mold, and improve the production efficiency and product quality. Now TS4 copper alloy mold has been successfully used in stainless steel sheet drawing mold, aluminum alloy die casting mold, plastic injection mold, copper alloy gravity casting and low pressure casting mold, glass bottle manufacturing mold, will replace the traditional mold steel and cast iron, can be called a revolution in the field of mold materials.
Laser surface hardening of metal materials can be used for surface hardening of metal materials to solve the contradiction between the whole strengthening and other surface hardening methods. It can also be used for surface modification of metal materials to obtain high-performance surface layer of low-grade materials. The die material substitution technology initiated by laser surface hardening technology opens up a new way to reduce the cost of die manufacturing.
1. Material substitution technology for cold working dies
Cold working die requires strength, toughness, wear resistance, fatigue resistance and bite resistance. The cold working die is made of medium and high carbon steel, low alloy steel or cast iron by laser phase transformation strengthening and replaced by traditional high grade materials. There is a wide range of technical application space. Although high alloy steels widely used in cold working dies have unique wear resistance of alloy carbides, laser transformation strengthening can compensate for the wear resistance of high alloy steels because of its non-oxidation, non-decarbonization and equal strength working layers such as dispersion strengthening, distortion strengthening, processing and heat treatment. Therefore, the advantages of laser enhanced process flexibility can be widely applied in the field of material substitution technology. When the working temperature of plastic mold is below 350 degrees, the same material is replaced by cold working die.
2. Material substitution technology for hot work dies
Hot working die materials require not only strength, toughness, wear resistance, fatigue resistance and bite resistance, but also red hardness and tempering resistance. Therefore, low material laser phase transformation can not replace high alloy steel with high temperature resistance. Mold remanufacturing technology and laser cladding can make carbon steel, low alloy steel or cast iron have high temperature resistance. When the working temperature of plastic mould is above 400 C, the same material substitution technology can be used for hot working die.
3. Cast iron mold
The enhancement potential of cast iron dies depends on whether the matrix is pearlite. If there is too much ferrite in the matrix, the hardenability of the material will be reduced, so the material substitution of the cast iron mold aims at improving the strengthening potential. According to the national standard, nodular cast iron should be selected over QT600, vermicular cast iron should be selected over RT380, and gray cast iron should be selected over HT200. At present, a large number of HT150 dies exist in the market.
4. Gear and mold remanufacturing technology
Laser cladding process is used to clad specific alloy materials on damaged or defective parts of gears or dies to form a good metallurgical bond with base metal materials. This repair process is not only for gears or dies