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What are the factors that affect the performance of the twin screw extruder

Date:2020-01-03

In recent years, with the continuous development of polymer modified materials, their requirements for mixing equipment have become higher and higher. Co-rotating parallel twin-screw extruder is one of the most widely used equipment in continuous mixers. Naturally, it has received wide attention from everyone, and more research has been conducted around it. At present, according to the development trend at home and abroad, the co-directional parallel twin screw extruder is mainly developed in terms of high speed, high torque, large extrusion volume and low energy consumption. Split-type parallel twin-screw extruder is a high-speed high-torque extruder that can quickly open the barrel for material cleaning.
The remarkable feature of the co-directional parallel twin-screw extruder is that the barrel can be split, and the screw and the barrel liner can be combined at will.
1. Split barrel. The barrel of the conventional co-rotating twin-screw extruder is integral and cannot be opened. The split parallel twin-screw extruder is a split type. It consists of two upper and lower half barrels, the lower half barrel is fixed on the frame, and the upper half barrel is connected to the lower half barrel through a worm reducer. . The upper and lower barrels are usually bolted with two rows of bolts. When the barrel needs to be opened, simply loosen the bolts and turn the handle of the worm gear box to open the barrel.
2. Building block screw and barrel. The screw and barrel of the main body of the split-type parallel twin-screw extruder adopt an advanced "block type" design. The screw is composed of various types of screw blocks set on the mandrel, and the liner inside the barrel The sleeve can be adjusted according to the different screw blocks, so that the ideal thread element structure can be flexibly combined according to the process requirements of the material type, etc., to achieve the material transportation, plasticization, thinning, shearing, venting, building pressure and extrusion. This process can better solve the contradiction between the so-called universality and specificity of the screw, which is generally difficult to take into account, and achieve the purpose of one machine with multiple functions and one machine with multiple functions. Another advantage of the "block type" design is that the worn screw and barrel components can be replaced locally, which avoids the scrap of the entire screw or barrel and greatly reduces maintenance costs.
The feeding system is the input end of the co-rotating parallel twin-screw extruder. Whether it works normally, stably, and on the ground will directly affect the performance of the co-rotating parallel twin-screw extruder. It is mainly reflected in the following three aspects:
(1) Feeding amount
The size of the main feeding amount affects the saturation of the whole machine. The feeding amount in the multi-channel feeding system not only affects the saturation of the whole machine, but also affects the formula of the material. Therefore, the matching of the feeding amount with the host and the nature of the feeding amount are very important.
(2) Stability
The feeding system of the parallel twin-screw extruder must work stably to ensure the normal operation of the parallel twin-screw extruder and the product quality. The stability here mainly refers to the rotational speed. A stable rotational speed can ensure a stable feeding amount, so the electronic control system generally outputs at a constant torque.
(3) Adaptability to materials
The same-direction parallel twin-screw extruder has many types of materials and different performances. According to the appearance, there are pellets, powders and mixtures, and a variety of additives are added. It is impossible for the same feeding system to achieve stable and ground feeding of each material. Therefore, it is difficult to improve the adaptability of the feeding system of the co-rotating parallel twin-screw extruder to the material, which is also a development direction.

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