First, the working belt on the aluminum profile mold must be ground and polished, and the work belt is generally required to be polished to the mirror surface. Check the flatness and verticality of the mold work belt before assembly. The quality of the nitriding determines the smoothness of the working belt polishing to a certain extent. The mold cavity must be cleaned with high-pressure gas and brush, and there must be no dust or foreign matter. Otherwise, it is easy to pull down the working belt in the metal flow, so that the extruded profile product has defects such as thick surface or scribe line.
Second, the mold holding time during extrusion production is generally about 2-3 hours, but can not exceed 8 hours, otherwise the hardness of the nitride layer of the mold working belt will be reduced, resulting in the surface roughness of the profile caused by the non-wearing on the machine, which will cause serious Defects such as scribing.
Third, use the correct alkaline washing (cooking mold) method. After the mold is unloaded, the mold temperature is above 500 °C. If it is immersed in the alkaline water immediately, the temperature of the alkaline water is much lower than the temperature of the mold. If the temperature of the mold drops rapidly, the mold is prone to cracking. The correct method is to place the mold in the air to 100 ° - 150 ° C and then immerse it in the alkaline water after the mold is unloaded.
Fourth, optimize the extrusion process. To scientifically extend the life of the mold, the rational use of the mold for production is an aspect that cannot be ignored. Due to the extremely harsh working conditions of the extrusion die, reasonable measures must be taken in the extrusion production to ensure the structural properties of the die.
5. The mold must be subjected to a reasonable surface nitriding process in the early stage of extrusion. Surface nitriding treatment can greatly improve the surface hardness of the mold while maintaining sufficient toughness to reduce the thermal wear of the mold during use. It should be noted that surface nitriding can not be completed once, and 3-4 times of repeated nitriding treatment must be carried out during the service of the mold. Generally, the thickness of the nitriding layer is required to be about 0.15 mm.
6. The use of the mold from low to high and then low. When the mold enters the service period, the internal metal structure performance is still in a floating stage. During this period, a low-intensity operation plan should be adopted to make the mold transition to a stable period.
7. Strengthen the use and maintenance records of the molds in the extrusion production process, and improve the tracking records and management of each set of molds. The extrusion die is received from the factory and the end of the mold is scrapped. The intermediate time is as short as several months and the length is longer than one year. Basically, the use record of the mold also records the various processes of profile production.
8. Choose a suitable extruder for production. Before the extrusion production, the section of the profile should be fully calculated, and the tonnage of the extruder should be determined according to the complexity of the profile section, the wall thickness and the extrusion coefficient λ.
Nine, aluminum alloy profile extrusion machine itself is ever-changing, and the aluminum extrusion industry has developed to today, aluminum alloy has important advantages such as light weight and good strength. At present, many industries have adopted aluminum profiles instead of the original materials. Due to the special shape of some profiles, the mold is difficult to design and manufacture due to the special section of the profile.
X. Reasonable choice of aluminum ingot and heating temperature. The alloy composition of the extruded ingot should be strictly controlled. At present, the general enterprise requires that the ingot grain size reach the first level standard to enhance plasticity and reduce anisotropy.