If the twin-screw extruder is divided into two key parts of "Extrusion" and "transmission", then the "extrusion part" is the key part of "ensuring quality", and the "transmission part" is the key part of "improving efficiency" and "ensuring quality".
Correspondingly, torque is the key parameter of transmission technology, which restricts the amount of feed and is also the most key technical index for the improvement of twin-screw performance. The screw clearance is the key parameter of the extrusion parts, controlling the residence time distribution of the processing material, the smaller the residence time distribution interval of the material in the barrel, indicating that the mixing time of the raw material in the barrel is consistent, the more stable the quality of the product, so the screw clearance is the most critical technical indicator for the stability of the quality of the extrusion product.
Small screw clearance can increase the efficiency of screw propulsion, reduce reflux and increase production; The uniform screw clearance ensures the uniform residence time distribution of the material in the barrel, so as to ensure the stability and consistency of the product quality, making it possible to precision extrusion and stable extrusion. The residence time of the material is stable and uniform, and the stability of the temperature control is improved, and the stability of the processing temperature ensures the process stability, and on the other hand, the quality of the extrusion products is stable.
As we all know, the screw clearance of German extruder is often very excellent, and it is also based on the breakthrough of their transmission system stable output technology, and only on the basis of stable output shaft runout and no change can a small screw clearance be used.
Table 1 lists several basic indicators representing the progress of twin-screw technology, 1, 2 and 3 respectively represent the grade of the product, the first level is the highest level, that is, the top level of extrusion technology in the world, the second level is the standard high-end configuration, and the third level is the current domestic general configuration. As can be seen from Table 1: under the premise of ensuring the bearing capacity of the gearbox, increasing the screw speed has a great contribution to improving production efficiency and reducing operating costs. With the increase of screw speed, the wear between the material and the component is accelerated, which reduces the service life of the component, and puts forward the requirements of the wear resistance of the material to us.
The main scheme is: the hot isostatic pressing powder metallurgy molding process (PM-HIP) is used to manufacture high-abrasion resistant materials. The steel WR15E and WR30 produced by this smelting process have both high wear resistance and high toughness, among which WR30 also has high corrosion resistance, and is the best material for processing high-strength and high-toughness long mandrel; WR5, WR14, MM60 have high wear resistance and excellent machinability, is the best material for processing screw components, WR14 has high corrosion resistance, MM60 has ultra-high wear resistance, can be used for processing metal powder processing technology; WR13 and WR5 can be cast into monolithic steel sleeves as barrel linings, of which WR13 not only has high wear resistance, but also has high corrosion resistance.
As can be seen from Table 4 and Table 5, the impact absorption work of the mandrel processed by powder metallurgy materials WR30 and WR15E is far greater than the corresponding value of the domestic common mandrel material 40CrNiMoA, which is about 3 times that of the domestic material, proving that the material has high impact performance and good toughness. It can be equipped with high torque gear box, which can greatly improve the output torque and production capacity of the equipment.
The application of the above materials can effectively improve the overall wear resistance of the extrusion parts of the equipment, so that it is possible to improve the service life of the extruder at high speed, which is also one of the several evaluation indicators of the extrusion equipment mentioned above. Of course, with the development of the domestic iron and steel smelting industry, the choice of such materials will be more and more.
Jwell started manufacturing screws and barrels in 1978, making it one of the earliest screw and barrel manufacturers in China. Its brand, "Jinhailuo", has become well recognized in the industry. In 1997, Jwell was established to begin the production of extrusion machinery. Today, Jwell is the vice president unit of the China Plastics Machinery Industry Association and one of the technology leaders in the extrusion machinery industry.
