Type and parameters of the screw conveyorAccording to the different types of materials transported, the screw conveyor can be divided into a screw with a shaft, a screw without a shaft, and a screw with a double shaft. Different types have different characteristics and applications. The following are some common models and parameters:
- Screw-type screw conveyor with shaft: It has a central shaft and is suitable for transporting materials that are not easy to stick and have a certain friction. There are certain requirements for the wear resistance of the screw conveyor. Its model parameters are consistent with the conventional model.
- Shaftless Auger Screw Conveyer (Take WLS Shaftless Auger as an example): It is suitable for transporting sticky, viscous and slow materials, such as sludge, garbage, etc. The shaft of the conveying screw and its internal bearings are not present, eliminating the problem of material accumulation and flow blockage, thus simplify the conveying process of these materials and generally improve the conveying efficiency. It is also used to convey products from the compounder, centrifugal machine and filter.
- Two-axis screw conveyor: Two seamless steel pipes are equipped with solid screw rods respectively. The screw rods on both sides turn in different directions to avoid material blockage caused by material accumulation. At the same time, it has the functions of conveying, mixing and stirring. The conveying capacity is 1.5 - 2 times that of a single shaft.
According to the different transportation methods, the screw conveyor can be divided into three types: horizontal, inclined, and vertical:
- Horizontal Auger Screw Conveyer: Horizontal arrangement, used to transport bulk materials from one part of a process to another part. By using multiple entrances and discharge points, the bulk materials can be effectively distributed to various positions on the Auger Screw Conveyer. Its model parameters are consistent with the conventional model.
- Inclined Engraving Spiral Conveyer: The angle of inclination ranges from 0 to 45 degrees above the horizontal line. With the increase of the inclination angle, the efficiency and load capacity of the screw conveyor decreased, and the power demand increased due to the gravitational pull and fall of the bulk material. It can be compensated by using a conveying screw with a reduced pitch (for example, one-half or two-thirds of the screw diameter). The use of a tube groove can also reduce the material fallback, and its model parameters are consistent with the conventional model.
- The vertical augers were used to transport bulk materials on vertical paths and very steep slopes (45 degrees above the water level). They were space and cost efficient in transporting bulk materials. However, controlling the amount of bulk materials fed into the screw conveyor was crucial to maintain a constant speed, reduce wear and power consumption, and improve the efficiency of the vertical screw conveyor. Therefore, a large number of measuring devices were needed, such as the screw feeder, whose model parameters were consistent with the conventional model.
In addition, different manufacturers may have their own specific models and parameters. For example, WAM's screw conveyor has the following different types:
- The vertical screw conveyor: The speed of the screw is higher than that of the ordinary screw conveyor. Under the effect of centrifugal force, the added material and the shell produce friction to prevent the material from rotating with the spiral blade, overcoming the gravity of the material falling, thus realizing the vertical transportation of the material. The machine has a small conveying capacity, a small conveying height, a high rotating speed, and a high energy consumption. It is especially suitable for conveying powder materials with good mobility. It is mainly used to lift materials. The lifting height is generally not more than 8 meters.
- Horizontal screw conveyor: When the material is added to the fixed tank, due to the gravity of the material and the friction between the material and the tank, the material piled up under the tank will not rotate with the screw, but will only move forward under the push of the rotating spiral blades. The machine is easy to load and unload at multiple points, and the mixing, stirring or cooling functions can be completed at the same time. It is sensitive to overload, easy to block, and has the loss of broken materials. It has a simple structure, convenient installation and maintenance, and convenient fault handling. It is suitable for horizontal or inclined (20 - 80 ° C). Compared with the vertical conveyor, its speed is relatively low, mainly used for horizontal or small inclination transportation of materials, the transmission distance is generally no more than 70 meters.
- Spiral pipe (roller conveyor) Conveyors: Continuous spiral blades are welded in a cylindrical shell, and the shell and spiral blades rotate together. Due to the effect of centrifugal force and friction force, the added material will rotate and rise together with the shell. Under the effect of the material gravity, it will slide along the spiral surface, causing the material to rotate with the spiral tube, thus realizing the forward movement of the material. This function has low energy consumption and low maintenance cost. When feeding from the end, it can meet the requirements of uneven feeding, and at the same time complete the process requirements of transportation, stirring, mixing, etc., and will not be blocked when too much material enters. It is convenient for multi-point loading and unloading, and can transport high-temperature materials. It is suitable for the horizontal transportation of high-temperature materials, and has good adaptability to high-temperature, uneven feeding, materials with crushing requirements and pollution requirements, and processes that require multi-point loading and unloading. Practice has proved that it has a good effect when transporting cement clinkers, dry limestone, phosphorous ore, titanium-iron powder, coal and slag. The particle size of the material added from the end feed port shall not be greater than 1/4 of the spiral diameter; the particle size of the material added from the middle feed port shall not be greater than 30mm. In order to ensure that the cylinder would not be deformed, the feeding temperature must be controlled below 300 ° C. When the machine was transporting the grinding materials, the blades and grooves were extremely worn.
- Curved Spiral Conveyer: The spiral core is flexible, and the transmission line can be arranged according to the space curve as needed. According to the length ratio of the horizontal and vertical (large inclination) sections in the layout of the line, the working principle of the ordinary screw conveyor or the vertical screw conveyor was designed. The transmission line needs to be arranged according to the space curve to avoid material transfer. When too many materials or hard materials enter the shell, the spiral body will float freely without blockage and low noise. It is mainly used to complete the horizontal and vertical transportation of materials at the same time. The vertical transportation generally requires a high speed, no less than 1000r/min.
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