Shaftless screw conveyor

Spiral conveyor is a mechanical device that uses an electric motor to drive a spiral to rotate and push materials to achieve the purpose of conveying. It can be transported horizontally, obliquely or vertically, with the advantages of simple structure, small cross-sectional area, good sealing, easy operation, easy maintenance, and convenient enclosed transportation. Spiral conveyors are divided into two types in terms of conveying form: axial spiral conveyors and shaftless spiral conveyors. They are also divided into U-shaped spiral conveyors and tubular spiral conveyors in terms of appearance. Axial screw conveyor is suitable for non viscous dry powder materials and small particle materials (For example: cement, fly ash, lime, grain, etc.) and shaftless screw conveyors are suitable for conveying materials that are viscous and easily entangled. The working principle of a screw conveyor (such as sludge, biomass, garbage, etc.) is that the rotating spiral blades push the material and transport it. The force that prevents the material from rotating together with the spiral conveyor blades is the weight of the material itself and the frictional resistance of the screw conveyor housing to the material. The spiral blades welded on the rotating shaft of the screw conveyor have different surface types depending on the conveyed material, including solid surface type, belt surface type, and blade surface type. The screw shaft of the screw conveyor has a thrust bearing at the end of the material movement direction to provide axial reaction force to the screw along with the material. When the machine is long, an intermediate suspension bearing should be added.

Features and Applications: Spiral conveyors have the following characteristics

1) The structure is relatively simple and the cost is low.

2) Reliable work and easy maintenance and management.

3) Compact size, small cross-sectional dimensions, and small footprint. Easy access to hatches and carriages during unloading operations at ports.

4) It can achieve sealed transportation, which is beneficial for transporting materials that are prone to flying, hot, and have strong odors, reducing environmental pollution, and improving the working conditions of port workers.

5) Easy loading and unloading. The horizontal screw conveyor can be loaded and unloaded at any point on its conveying line; The configuration of a vertical spiral conveyor with a relatively spiral material retrieval device can have excellent material retrieval performance.

6) It can be used for reverse conveying or for a conveyor to simultaneously transport materials in two directions, either towards the center or away from the center.

7) The unit energy consumption is relatively high.

8) Materials are prone to crushing and wear during transportation, and the wear of spiral blades and material troughs is also quite severe.

structure characteristics

(1) There are three types of spiral blades for screw conveyors: solid spiral surface type, belt spiral surface type, and blade spiral surface type. The solid spiral surface is called the s-method, and its spiral pitch GX type is 0.8 times the blade diameter. The LS type spiral conveyor is suitable for conveying powdered and granular materials. Belt type helical surface, also known as D method, has a helical pitch equal to the diameter of the helical blades, and is suitable for conveying powdered and small materials. The blade type helical surface is rarely used and is mainly used for conveying materials with high viscosity and compressibility. During the conveying process, it completes mixing and other processes simultaneously, and its helical pitch is about 1.2 times the diameter of the helical blade.

(2) The spiral blades of a screw conveyor have two directions of rotation: left-handed and right-handed.

(3) The types of screw conveyors include horizontal fixed screw conveyors and vertical screw conveyors. Horizontal fixed screw conveyor is a commonly used type. Vertical spiral conveyor is used for short distance material lifting, with a conveying height generally not exceeding 8m. The spiral blades are solid surface type, and it must have horizontal spiral feeding to ensure the necessary feeding pressure. 

(4) The material outlet end of LS and GX spiral conveyors should be equipped with 1/2 to 1 circle of reverse spiral blades to prevent powder from blocking the end.

(5) The screw conveyor consists of three parts: the screw machine body, the inlet and outlet, and the driving device. The main body of the screw machine consists of a head bearing, a tail bearing, a suspension bearing, a screw, a casing, a cover plate, and a base. The driving device consists of an electric motor, a reducer, a coupling, and a base.