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From the perspective of the direction in which the material is conveyed, screw conveyors can be divided into two main types: horizontal screw conveyors and vertical screw conveyors. Screw conveyors that use high-strength plastic for their conveying screws are also known as food screw conveyors or screw elevators; they are primarily used for transporting large-sized products. Such as cartons, turnover boxes, bottled water, etc. Depending on the requirements of the materials being transported and the structure, screw conveyors include horizontal screw conveyors, vertical screw conveyors, bendable screw conveyors, and screw tube (roller conveyor) conveyors. (1) Vertical screw conveyor: The rotation speed of the screw in a vertical screw conveyor is higher than that in a conventional screw conveyor. The material fed into this conveyor experiences friction with the casing due to centrifugal force; this friction prevents the material from rotating together with the screw blades and overcomes the gravitational force acting on the material, thereby enabling the vertical transport of the material. This machine has a low conveying capacity, a low conveying height, a high rotation speed, and high energy consumption. It is particularly suitable for transporting powdery and granular materials with good fluidity, and is mainly used for lifting such materials; the lifting height is generally not more than 8 meters. (2) In a horizontal screw conveyor, when material is fed into the fixed trough, due to the gravity of the material and the friction between it and the trough, the material piled at the bottom of the trough does not rotate along with the screw. Instead, it moves forward only under the push of the rotating screw blades, similar to a non-rotating nut moving in translation along a rotating screw, thereby achieving the purpose of transporting the material. This machine facilitates loading and unloading at multiple points, and can perform mixing, stirring, or cooling functions simultaneously during the conveying process. Sensitive to overload, prone to clogging ； There is crushing loss of the material, and the horizontal screw conveyor has a simple structure, making it easy to install, maintain, and troubleshoot. Suitable for the continuous and uniform transport of loose materials in a horizontal or slightly inclined position (up to 20°). The operating temperature range is -20 to +40°C, while the temperature of the materials being transported ranges from -20 to +80°C. Its rotation speed is lower compared to vertical conveyors; it is mainly used for transporting materials horizontally or at a slight inclination, with the conveying distance generally not exceeding 70 meters. (3) Screw tube (conveyor belt) conveyor: A screw tube conveyor is a device in which continuous spiral blades are welded inside a cylindrical casing, and the casing rotates together with these spiral blades. The material added rotates together with the shell due to centrifugal force and friction; after being lifted, it slides down along the spiral surface under the effect of gravity, causing the material to rotate along with the spiral tube and thus enabling its forward movement. This is similar to a non-rotating screw moving in translation relative to a rotating nut, thereby achieving the purpose of transporting the material. This machine has low energy consumption and low maintenance costs ； When feeding at the end, it can meet the requirements of uneven feeding, and it is capable of fulfilling various process requirements such as conveying, stirring, and mixing; there is no risk of blockage even when an excessive amount of material is fed in ； It facilitates multi-point loading and unloading, and can transport materials at higher temperatures. Suitable for horizontally transporting high-temperature materials ； It has good adaptability to materials that require high temperatures, uniform feeding, impact protection, and contamination prevention, as well as to processes that involve multiple loading and unloading points. Practice has shown that it performs well in transporting materials such as cement clinker, dried limestone, phosphate rock, ilmenite powder, coal, and slag. The material fed in through the end inlet must have a particle size not larger than 1/4 of the spiral diameter ； The particle size of the material fed through the intermediate feed port must not exceed 30 millimeters. To prevent deformation of the cylinder, the feeding temperature must be kept below 300°C. This machine causes extremely severe wear on the blades and chutes when transporting materials with high abrasiveness. The screw conveyor designed this time is mainly used for transporting silicon micropowder; due to its high abrasiveness, it is not suitable to use a screw tube conveyor. (4) Flexible screw conveyor: The screw shaft of this conveyor is flexible, allowing the conveying path to be arranged in a spatial curve as required. Depending on the length ratio of the horizontal and vertical (high-inclination) sections in the layout, its operating principle is designed either as a conventional screw conveyor or a vertical screw conveyor. Used in transmission lines that need to be arranged along spatial curves to avoid the need for material transfer ； When too much material or hard objects enter the casing, the screw will float freely and there will be no jamming ； Low noise. It is mainly used to simultaneously perform horizontal and vertical transportation of materials. For vertical transportation, it is generally required that the rotational speed be high, not less than 1000 r/min.