Screw Conveyor

Equipment Introduction

Screw conveyors are closed, continuous conveying equipment without traction components. The industry mainstream models are divided into two main series: LS (shafted U-type/tubular) and WLS (shaftless). They rely on rotating helical blades to push materials and are widely used in complete production lines for organic fertilizers and compound fertilizers. They are primarily used for short-distance closed transfer, quantitative feeding, and integrated mixing of powders and granules. Core Advantages (Suitable for the Fertilizer Industry)

1. Fully Enclosed and Dust-Free: U-shaped cover/tube-type sealed structure ensures no dust leakage during the conveying of fertilizers and manure powder, meeting environmental protection standards.

2. Compact Space and Flexible Layout: Can be arranged horizontally or at an angle of ≤20°, with multiple feeding and unloading points, suitable for batching silos and granulators for quantitative feeding.

3. Combines Conveying and Mixing Functions: Simultaneously mixes materials during conveying, eliminating the need for separate mixing equipment.

4. Low Cost and Small Footprint: Replaces belt conveyors for short-distance conveying, making it the preferred choice for small plant environments.

5. Variable Frequency Precision Material Control: Enables stable quantitative batching, making it a core feeding device in fertilizer batching processes.

Structural Composition

A complete screw conveyor typically consists of three main parts: the screw conveyor body, the inlet/outlet device, and the drive unit. The screw conveyor body is the core component, composed of a head section, an intermediate section, and a tail section.

Specifically, its main components include:

Screw (Auger): The main component for material conveying, consisting of screw blades and a screw shaft. Screw blades come in various types depending on the material, such as solid (full-surface) and ribbon-face. The screw shaft is usually made of hollow steel tubing with a diameter of 30–70 mm.

Bearings: Used to support the screw, and are classified into three types according to their location:

Head Bearing: Installed at the discharge end, bearing radial and axial forces, using a radial thrust bearing.

Tail Bearing: Installed at the inlet end, bearing only radial forces, using a radial spherical bearing.

Intermediate Hanger Bearing: When the screw shaft length exceeds 3 meters, it needs to be installed in the middle to prevent bending.

Material trough (casing): Usually made of thin steel plate, with a semi-circular bottom cross-section, used to hold the conveyed material.

Drive unit: Consists of an electric motor, reducer, and transmission components, providing power to the equipment.

Working Principle

The motor drives the screw shaft to rotate at a constant speed. Material falls into the machine casing from the feed inlet. The rotating screw blades generate axial thrust. Constrained by friction at the bottom of the trough, the material does not rotate with the blades circumferentially, but is propelled forward along the axial direction of the casing and continuously discharged from the discharge port.

1. Horizontal Conveying: Thrust directly pushes the material.

2. Inclined Upward Conveying: Relies on the blades to lift and counteract the downward force of the material; the larger the angle, the lower the conveying efficiency.

3. Shaftless Model: Flexible integral screw directly pushes the material, eliminating the obstruction of viscous wet materials by the absence of a hanging shaft, preventing entanglement and blockage.

Equipment applicable raw materials