At the same time, the influencing factors are not single, but a Comprehensive and complex multi-factor problem. However, based on the analysis of the above failure modes and their causes, we have ideas and methods on how to increase the life of aluminum extrusion dies. The author believes that to improve the life of the die mainly from the following aspects: (1) reasonable design of the die, die Reasonable and proper design is an important part of prolonging its service life. Properly designed mold structure should ensure that there is no possibility of impact cracking and stress concentration under normal use conditions. Therefore, when designing the mold, try to make the parts uniformly stressed, and pay attention to avoid sharp corners, concave angles, and wall thickness differences Disparity, flat width and thin wall section, etc., to avoid excessive stress concentration, causing heat treatment deformation, cracking and brittle fracture or early thermal cracking during use. At the same time, standardized design is conducive to the exchange, storage and maintenance of molds. In general, reasonable mold structure design and reliable strength are more core, and there are constant innovations in mold design theory and methods. The use of electronic computer-aided design is the main way to improve extrusion mold design and increase service life. (2) Reasonable selection of mold materials. Extrusion molds are operated under high temperature and high pressure, and bear the role of periodic loads. The working conditions and environment are very harsh. Therefore, the performance requirements of mold steel are quite high, and the materials used to make molds should be good. The thermal stability, thermal fatigue, thermal wear resistance and sufficient toughness. At present, the mold materials commonly used in China are 4Cr5MoSiV1H13 steel and 3Cr2W8V steel, but in recent years, due to the low toughness of 3Cr2W8V steel and poor fatigue resistance, even high-temperature quenching and other process treatment measures cannot meet the requirements, and the early failure of the mold is more serious , The new steel grade 4Cr5MoSiV1H13 steel has good hardenability, thermal strength, wear resistance and plasticity, high impact toughness, resistance to cold and hot fatigue, small heat treatment deformation, good crack propagation resistance, can improve extrusion The surface roughness of the profile, easy mold repair, good high-temperature comprehensive performance and the structure contain more Cr and Mo elements, which can produce rich and stable nitrides and dispersion characteristics during nitriding treatment, so it gradually replaced Cr2W8V steel has become the material of choice for extrusion dies. Practical data also proves that: 4Cr5MoSiV1 steel and 3Cr2W8V steel are used to manufacture the same kind of mold. The life of 4Cr5MoSiV1 is 3 to 5 times longer than that of 3Cr2W8V 1. Of course, the choice of mold materials is also a very complicated issue, which involves a wide range of areas. Only by combining new materials development and improvement of the quality of the material itself with the research of new heat treatment processes and surface strengthening treatment processes is it an effective way to improve life. (3) Improve the quality of heat treatment and surface treatment. The service life of the extrusion die depends largely on the quality of heat treatment. Therefore, advanced heat treatment methods and heat treatment processes as well as toughening treatment and surface strengthening treatment are particularly important to increase the service life of the die At the same time, strictly control the heat treatment and surface strengthening process to prevent heat treatment defects, adjust the quenching and tempering process parameters, increase the number of pretreatment, stabilization and tempering, pay attention to temperature control, heating and cooling strength, use new quenching media and research New technology and new equipment such as toughening treatment and various surface strengthening treatments are conducive to the improvement of the service life of the mold. (4) Improve the processing quality in mold manufacturing. During the processing of molds, common processing methods include mechanical processing, wire cutting processing, and electrical discharge processing. Mechanical processing is an indispensable important process in the mold processing process. It not only changes the appearance size of the mold, but also directly affects the quality of the profile and the service life of the mold. Wire cutting processing of die holes is a widely used method in mold processing, which improves Processing efficiency and processing accuracy, but also bring some special problems, such as the mold processed by wire cutting, if it is directly used for production without tempering, it is easy to produce slag, flaking and other phenomena, which will reduce the service life of the mold. Therefore, fully tempering the die after wire cutting can improve the surface tensile stress state, reduce residual stress, and increase the service life of the die. Stress concentration is the main reason for mold fracture. Within the range allowed by the design of the drawing, the larger the diameter of the wire cutting wire, the better. This not only helps to improve the processing efficiency, but also greatly improves the distribution of stress and prevents the occurrence of stress concentration; discharge machining It is a kind of electro-corrosion processing carried out by the superposition effect of material vaporization, melting and machining liquid evaporation phenomenon generated during discharge. The problem is that due to the heat effect of heating and cooling and the electrochemical action of the machining fluid, a metamorphic layer is formed at the machining site to generate strain and stress. When the machining fluid is oil, the carbon atoms decomposed by the combustion of the oil Diffusion and carburization to the surface to be processed, while the thermal stress increases, the brittle hard and easy to crack, and at the same time constitute residual stress and attach to the workpiece, which will cause fatigue strength reduction, accelerated fracture, stress corrosion and other phenomena . Therefore, in the process of processing, the above problems should be prevented as bronze cast factory much as possible to improve the processing quality. (5) Improve the working conditions and the extrusion process conditions. The working conditions of the extrusion die are extremely poor and the environment is very bad. Therefore, improving the extrusion process methods and process parameters, improving the working conditions and working environment are beneficial to increasing the life of the die. Therefore, we must carefully formulate the extrusion plan before extrusion, select the best equipment system and blank specifications, formulate the best extrusion process parameters (such as extrusion temperature, speed, extrusion coefficient and extrusion pressure, etc.) and improve Working environment during extrusion (such as water cooling or nitrogen cooling, sufficient lubrication, etc.), reduce the work load of the mold (such as reducing extrusion force, reducing chilling shock and alternating load, etc.), establishing and perfecting process operation rules and Safe use regulations. 3 Conclusion In the actual production and working process, the service life of the extrusion die is a comprehensive technical problem. The five aspects described above are only the main part of it. The reasonable use and maintenance of the die and scientific management of extended extrusion The service life of the mold is also critical.
