Wear situation
Due to the convenient opening, the wear degree of the screw elements and the inner liner of the barrel can be found at any time, so effective maintenance or replacement can be carried out. It will not be found when there is a problem with the extruded product, causing unnecessary waste.

Reduce production costs
When manufacturing masterbatches, colors often need to be changed. If it is necessary to change products, the open processing area can be opened in a few minutes. In addition, the mixing process can be analyzed by observing the melt profile on the entire screw. At present, when ordinary twin-screw extruders change colors, a large amount of cleaning materials are needed for cleaning, which is time-consuming, power-consuming and wastes raw materials. The split twin-screw extruder can solve this problem. When changing colors, only a few minutes are needed to quickly open the barrel for manual cleaning, so that less or no cleaning materials are needed, saving costs.

Improve labor efficiency
During equipment maintenance, ordinary twin-screw extruders often need to remove the heating and cooling systems first, and then withdraw the screw as a whole. However, the split twin-screw extruder does not need this. Just loosen a few bolts and turn the handle device of the worm gear box to lift the upper half of the barrel to open the entire barrel, and then carry out maintenance. This not only shortens the maintenance time but also reduces the labor intensity.

High torque and high speed
At present, the development trend of twin-screw extruders in the world is towards high torque, high speed and low energy consumption. The effect brought by high speed is high productivity. The split twin-screw extruder belongs to this category, and its speed can reach 500 revolutions per minute. Therefore, it has unique advantages in processing high-viscosity and heat-sensitive materials.

Wide application range
It has a wide range of applications and can be suitable for the processing of various materials.

High output and high quality
It has other advantages of ordinary twin-screw extruders and can achieve high output, high quality and high efficiency.

Material transmission mode
In a single-screw extruder, friction drag occurs in the solid conveying section and viscous drag occurs in the melt conveying section. The friction performance of solid materials and the viscosity of molten materials determine the conveying behavior. For example, if some materials have poor friction performance, if the feeding problem is not solved, it is difficult to feed the material into a single-screw extruder. In a twin-screw extruder, especially a meshing twin-screw extruder, the transmission of materials is to some extent positive displacement transmission. The degree of positive displacement depends on the closeness of the relative screw grooves of one screw to the screw flights of the other screw. The screw geometry of a closely meshed counter-rotating extruder can obtain a high degree of positive displacement conveying characteristics.

Material flow velocity field
At present, the flow velocity distribution of materials in a single-screw extruder has been described quite clearly, while the flow velocity distribution of materials in a twin-screw extruder is quite complex and difficult to describe. Many researchers only analyze the flow velocity field of materials without considering the material flow in the meshing area, but these analysis results are very different from the actual situation. Because the mixing characteristics and overall behavior of a twin-screw extruder mainly depend on the leakage flow occurring in the meshing area, however, the flow situation in the meshing area is quite complex. The complex flow spectrum of materials in a twin-screw extruder shows advantages that a single-screw extruder cannot match on a macroscopic scale, such as sufficient mixing, good heat transfer, large melting capacity, strong exhaust capacity and good control of material temperature.

1.Glass fiber reinforced and flame retardant pelletizing (such as PA6, PA66, PET, PBT, PP. PC reinforced flame retardant, etc.).

High filling pelletizing (such as PE, PP filled with 75% CaCO.).

Heat-sensitive material pelletizing (such as PVC, XLPE cable material).

Dark masterbatch (such as filled with 50% toner).

Antistatic masterbatch, alloy, coloring, low filling blending and pelletizing.

Cable material pelletizing (such as sheath material, insulation material).

XLPE pipe material pelletizing (such as masterbatch for hot water cross-linking).

Mixing and extrusion of thermosetting plastics (such as phenolic resin, epoxy resin, powder coatings).

Hot melt adhesive, PU reaction extrusion and pelletizing (such as EVA hot melt adhesive, polyurethane).

K resin, SBS devolatilization and pelletizing.

Straightening device
One of the most common types of plastic extrusion waste is eccentricity, and various types of bending of the wire core are important reasons for generating insulation eccentricity. In sheath extrusion, scratches on the sheath surface are often caused by the bending of the cable core. Therefore, straightening devices are essential in various extrusion units. The main types of straightening devices are: drum type (divided into horizontal type and vertical type); pulley type (divided into single pulley and pulley block); capstan type, which also plays multiple roles such as dragging, straightening and stabilizing tension; pressure wheel type (divided into horizontal type and vertical type), etc.

Preheating device
Cable core preheating is necessary for both insulation extrusion and sheath extrusion. For insulation layers, especially thin insulation layers, the existence of air holes cannot be allowed. The wire core can be thoroughly cleaned of surface moisture and oil stains by high-temperature preheating before extrusion. For sheath extrusion, its main function is to dry the cable core and prevent the possibility of air holes in the sheath due to the action of moisture (or the moisture of the wrapped cushion layer). Preheating can also prevent the residual internal pressure in the plastic due to sudden cooling during extrusion. In the extrusion process, preheating can eliminate the cold wire entering the high-temperature machine head and the huge temperature difference formed when it contacts the plastic at the die opening, avoid the fluctuation of the plastic temperature and thus the fluctuation of the extrusion pressure, thereby stabilizing the extrusion amount and ensuring the extrusion quality. Electric heating wire core preheating devices are all used in extrusion units, which require sufficient capacity and rapid heating to ensure high efficiency of wire core preheating and cable core drying. The preheating temperature is restricted by the payoff speed and is generally similar to the machine head temperature.

Cooling device
The formed plastic extrusion layer should be cooled and shaped immediately after leaving the machine head, otherwise it will deform under the action of gravity. The cooling method is usually water cooling, and according to different water temperatures, it is divided into rapid cooling and slow cooling. Rapid cooling is direct cooling with cold water. Rapid cooling is beneficial to the shaping of the plastic extrusion layer, but for crystalline polymers, due to sudden heating and cooling, internal stress is easily remaining inside the extrusion layer structure, which may lead to cracking during use. Generally, PVC plastic layers use rapid cooling. Slow cooling is to reduce the internal stress of the product. Different temperature water is placed in sections in the cooling water tank to gradually cool and shape the product. For the extrusion of PE and PP, slow cooling is used, that is, three stages of cooling through hot water, warm water and cold water.

After 500 hours of use, there will be iron filings or other impurities worn off by gears in the reduction gearbox. Therefore, the gears should be cleaned and the lubricating oil in the reduction gearbox should be replaced.

After using it for a period of time, a comprehensive inspection of the extruder should be carried out to check the tightness of all screws.

If there is a sudden power failure during production and the main drive and heating stop, when the power supply is restored, each section of the barrel must be reheated to the specified temperature and kept warm for a period of time before the extruder can be started.

If it is found that the instrument and pointer are fully deflected, check whether the contacts of the thermocouple and other wires are in good condition.

Structural principle
For the basic mechanism of the extrusion process, simply put, it is a screw rotating in the barrel and pushing the plastic forward. The screw structure is a slope or ramp wound on the central layer, and its purpose is to increase pressure to overcome greater resistance. For an extruder, there are three kinds of resistance that need to be overcome during operation: one is friction, which includes two kinds of friction between solid particles (feed) and the barrel wall and the mutual friction between them in the first few turns of the screw (feeding zone); the second is the adhesion of the melt on the barrel wall; the third is the internal flow resistance of the melt when it is pushed forward.

Temperature principle
Extrudable plastics are thermoplastics that melt when heated and solidify again when cooled. Therefore, heat is needed in the extrusion process to ensure that the plastic can reach the melting temperature. So where does the heat for melting plastic come from? First of all, the feed preheating of the weighbridge and the barrel/mold heater may play a role and are very important at startup. In addition, the motor input energy, that is, the frictional heat generated in the barrel when the motor overcomes the resistance of the viscous melt and rotates the screw, is also the most important heat source for all plastics. Of course, except for small systems, low-speed screws, high melt temperature plastics and extrusion coating applications. In operation, it is important to realize that the barrel heater is actually not the main heat source. Its effect on extrusion may be smaller than we expected. The temperature of the rear barrel is more important because it affects the conveying speed of solids in the meshing or feeding. Generally speaking, except for some specific purposes (such as glazing, fluid distribution or pressure control), the die and mold temperatures should reach or be close to the temperature required by the melt.

Deceleration principle
In most extruders, the change of screw speed is achieved by adjusting the motor speed. The drive motor usually rotates at full speed of about 1750 rpm, which is too fast for a screw of an extruder. If it rotates at such a high speed, too much frictional heat will be generated, and a uniformly and well-stirred melt cannot be prepared due to the short residence time of the plastic. The typical reduction ratio should be between 10:1 and 20:1. The first stage can use either gears or pulley blocks, but in the second stage, gears are preferably used and the screw is positioned at the center of the last large gear. For some slow-running machines (such as twin-screw extruders for UPVC), there may be three deceleration stages, and the maximum speed may be as low as 30 rpm or lower (ratio up to 60:1). On the other hand, some very long twin screws used for stirring can run at 600 rpm or faster, so a very low reduction rate and more deep cooling are required. If the reduction rate is mismatched with the work, too much energy will be wasted. At this time, a pulley block may need to be added between the motor and the first reduction stage that changes the maximum speed. This either increases the screw speed and even exceeds the previous limit, or reduces the maximum speed. This can increase the available energy, reduce the current value and avoid motor failure. In both cases, due to material and its cooling requirements, the output may increase.