double screw extruder is the key equipment in the modification process of plastic polymer materials. The design and manufacturing level of cylinder and screw in the processing section is the core factor to determine the quality of processing materials. In production practice, its service life is the focus of many users.
Nanjing KY Chemical Machinery Co., Ltd. (hereinafter referred to as Nanjing KEYA) is committed to the research on the high-speed and high torsion development of double screw extruder, as well as the optimization of processing section and the innovation of product service life technology.
In daily production, in order to improve the wear resistance of the inner surface of the cylinder, the traditional method is to inlay the splayed hole in the cylinder with the alloy sleeve to improve the wear resistance of the cylinder. The defect of this method is that the gap between the alloy sleeve and the cylinder is easy to squeeze into the raw materials, resulting in corrosion damage of the cylinder materials and increased material residue.
In order to solve the defects of the above methods, the common improvement technical schemes in production practice are: the alloy sleeve is made into a whole and embedded into the cylinder body. Although this method solves the above problems, the thermal expansion coefficient of the body and the overall alloy sleeve is quite different after the cylinder is heated, resulting in the possible material leakage due to the gap between the body and the alloy sleeve. Especially when the viscosity difference between the two materials is large, the service life is still not long.
In view of the above problems, Nanjing KEYA pioneered the use of metal sintering technology to sinter the alloy powder on the surface of the splayed hole in the cylinder through a special technology to form a uniform and dense alloy layer. The alloy layer not only solves the defects of the traditional scheme, but also has good corrosion and wear resistance, long service life and low cost.
The realization of this technology can solve the frequent shutdown and replacement of spare parts caused by wear-resistant problems of the majority of double screw extruder users under working conditions. It can also customize alloy materials according to the corrosion-resistant and wear-resistant requirements to meet the process requirements of various materials.
After the test, the wear resistance and corrosion resistance of the scheme are greatly improved (compared with 6542 tool steel, the weight loss ratio is 1:3; corrosion test: it is immersed in hydrogen chloride HCl solution with 304 stainless steel, and the corrosion rate ratio is 0.4:1).
In addition to being successful in the design and development of special screw components, Nanjing KEYA has also continued to increase investment in the processing accuracy and processing technology of screw components in recent years.
The improvement of the surface finish of the screw element of the double screw extruder not only reduces the wear of the material to the element, but also makes the replacement rate of the material on the surface of the screw higher (reducing the residence time of the material on the surface of the screw), especially for the performance improvement of heat sensitive materials; The high finish of the screw also makes the screw cleaning more convenient, reduces the labor intensity and improves the production efficiency.
In addition, the special surface treatment technology of screw components newly developed by Nanjing KEYA can make the surface hardness of components reach HV3500. The color is black gray and the coating thickness is 4.0-6.0 μm. The maximum working temperature is 900 ℃ and the friction coefficient is 0.3. While improving the surface hardness, it also maintains good coating toughness, adhesion and lubricity.
The application of the new technology in the above processing section can facilitate the IE engineers to adapt to more material formulas for process design, reflect the comprehensive competitiveness and wide applicability of Nanjing KEYA's complete machine products, and provide a reliable guarantee for more users to replace high-speed and high torque equipment.
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