Screw conveyor

Screw conveyor is a common material conveying device that uses a central shaft or shaftless spiral blade to rotate in the trough to push the material in a horizontal, inclined or vertical direction. The equipment is mainly composed of spiral blades, bearing supports, drive mechanisms and closed or semi-enclosed troughs. After the material enters the trough, it is transported forward under the push of the blades and transferred or unloaded at the outlet. The layout of the screw conveyor can be adjusted according to the on-site space and process requirements. It can be laid horizontally or installed at an angle or vertically. The equipment has a compact structure and occupies a relatively small area. The blades and trough can be cleaned through the inspection port during maintenance. The applicable material range covers dry powder, granules, small pieces and semi-fluid materials of a certain viscosity. Principle of screw conveyor
The core component of screw conveyor is the spiral blade welded or wound along the central axis. It is installed in a U-shaped trough or round tube. The blade is driven to rotate by the motor and reducer, thereby pushing the material along the bottom of the trough or tube. When the blade rotates, the material forms a pushing force between the spiral blade and the trough, causing the material to move along the axial direction, thereby realizing horizontal, inclined or vertical transportation.
According to the structural form, screw conveyors are divided into two types: shafted and shaftless. The shafted screw has blades welded on the central axis. The structure is simple, but it may cause hanging or blockage when conveying sticky or wet materials; the shaftless screw replaces the central axis with a continuous spiral body, which reduces the adhesion and blockage of materials during the conveying process. According to the conveying direction and installation angle, it can be divided into three types: horizontal, inclined and vertical. When arranged horizontally, the material mainly moves along the horizontal plane under the thrust of the blades, and does not rely on gravity for unloading; the inclined arrangement angle generally does not exceed 45°. When the inclination angle increases to the critical value, it is necessary to set a variable pitch on the blade or install an anti-backflow device; when arranged vertically, it is necessary to overcome the gravity of the material, and the spiral blades often adopt a variable pitch design, and the driving power is required to be increased accordingly.
In addition, the screw conveyor can be equipped with a closed structure, an inspection door, a cleaning device and a flow adjustment mechanism according to the process requirements to meet the requirements of closed transportation, leakage prevention and online cleaning. Advantages and characteristics of screw conveyors
Compact structure and small footprint: The combination of the trough and the screw shaft of the screw conveyor is simple, and can be arranged along the wall or beside the equipment without taking up too much plane space.
Good sealing performance: The fully enclosed pipe body or U-shaped trough with a cover plate design helps to suppress dust escape and liquid leakage, and meet the process cleanliness requirements.
Applicable to a wide range of material types: It can convey dry powder, particles, small pieces and slurry materials with a certain viscosity, and its application scope covers grain, chemical industry, building materials, mining and other fields.
Easy installation and maintenance: An inspection port or disassembly door is set on the trough body, and the screw can be quickly replaced and the residual material can be cleaned up in the shutdown state; the tensioning device can adjust the gap between the screw and the trough body, which is convenient for daily maintenance.
Adjustable conveying capacity: By frequency conversion speed regulation or selecting spiral blades with different pitches, the material conveying capacity per unit time can be adjusted within a certain range.
Pressure resistance and corrosion resistance: The selection of stainless steel or wear-resistant alloy materials can operate in corrosive environments or high temperature occasions, and the closed structure can withstand a certain internal pressure. Application of screw conveyors
Building materials industry: In cement plants, screw conveyors are used for discharging materials from grinding mills, pipe transportation of mixtures after clinker cooling, and discharging materials from the bottom of cement silos. In sand and gravel plants, it is often used for transitional transportation between crushers and screens to maintain the continuity of material flow.
Chemical industry: In the chemical production process, screw conveyors can complete the quantitative mixing, batching and dryer feeding of solid raw materials;
Grain and feed processing: Granaries and feed plants often use screw conveyors for in-silo transportation of bulk grains such as grains, corn, and soybeans and feeding of batching systems. Shaftless screws can reduce the frequency of blockages and cleaning when conveying feed raw materials that are prone to dust or adhesion.
Mining and metallurgy: Screw conveyors are used for the transportation of ore, mineral powder and tailings in the mineral processing process, and can also undertake the task of closed transportation of high-temperature slag or ash in metallurgical plants. In steel plant auxiliary equipment, screw conveyors can also be used for quantitative addition of coal powder and coke powder. The screw conveyor achieves continuous material conveying and quantitative control by means of the synergistic effect of the rotating blades and the trough. Its design can be divided into two forms, with or without a shaft, to meet the requirements of different material adhesion and fluidity; in horizontal, inclined or vertical arrangements, the equipment can be docked with other devices to complete multi-link process flows. Daily maintenance includes cleaning up residual materials, checking bearings and tensioning devices to ensure smooth conveying channels. Selecting the appropriate pitch, blade form and drive power according to the material characteristics can reduce blockage and backflow while ensuring stable conveying.