1. Definition
A screw conveyor (also known as an auger conveyor, and referred to as 绞龙 in Chinese industrial practice) is a continuous conveying machine that moves powdery, granular and small-lump materials along the axis of an enclosed trough by means of a rotating screw shaft fitted with helical flights.
2. Working Principle
When the screw shaft rotates, the material does not rotate with the flights; restrained by gravity and by friction with the trough wall, it is pushed forward along the axis like a “non-rotating nut” and is finally discharged from the outlet. Horizontal screw conveyors convey materials mainly by friction, while vertical screw conveyors rely mainly on centrifugal force.
3. Structure and Main Components
A screw conveyor mainly consists of: the drive unit (motor and gear reducer), the screw shaft (central shaft with helical flights), the casing or trough (U-shaped or tubular), the feed inlet, the discharge outlet, and the head and tail bearings. For conveyors longer than about 5 m, intermediate hanger bearings are installed in the middle section to maintain shaft stiffness and limit deflection; the trade-off is a more complex structure and slightly obstructed material flow. The LS series is the current mainstream product and is an upgraded version of the earlier GX series.
4. Classification
- By installation angle: horizontal (0°–20°), inclined, and vertical screw conveyors.
- By shaft structure: the shafted type (with a central shaft; LS and GX series, the most widely used) and the shaftless type (suitable for easily entangled materials such as sludge and municipal solid waste).
- By pitch form: standard pitch (S = D, universally applicable), short pitch (S ≈ 2/3D, recommended for inclinations above 20° and for screw feeders, to prevent free flow of fluidized materials), and double-flight screws (giving smooth and uniform conveying).
5. Key Parameters and Selection
The main parameters of a screw conveyor are: screw diameter D (commonly 160–1250 mm for the LS series), pitch S (generally 0.5–1.0 times the diameter; standard pitch S = D), rotation speed n (depending on diameter and material, typically 36–112 r/min for the LS series), capacity Q, filling factor ψ (empirical value 0.15–0.45, selected according to material abrasiveness and flowability), and inclination correction factor C (which decreases as the installation angle increases). Capacity increases with D, S, n, ψ and C. Table 1 gives typical capacity figures of the LS series.
| Model | Screw diameter (mm) | Rotation speed (r/min) | Capacity (m³/h) |
|---|---|---|---|
| LS160 | 160 | 112 / 90 / 71 / 56 | 9.7–3.2 / 7.8–2.6 / 6.2–2.1 / 4.9–1.6 |
| LS200 | 200 | 100 / 80 / 63 / 50 | 16.9–5.6 / 13.5–4.5 / 10.7–3.6 / 8.5–2.8 |
| LS250 | 250 | 90 / 71 / 56 / 45 | 29.9–9.9 / 23.5–7.8 / 18.5–6.2 / 14.9–5.0 |
| LS315 | 315 | 80 / 63 / 50 / 40 | 52.9–17.6 / 41.6–13.9 / 33.1–11.0 / 26.4–8.8 |
| LS400 | 400 | 71 / 56 / 45 / 36 | 85.3–28.2 / 67.3–22.4 / 54.1–18.0 / 43.2–14.4 |
Note: The capacity ranges correspond to different material filling ratios; actual values vary with material properties, conveying length and installation conditions.
6. Advantages and Disadvantages
Advantages:
- Simple structure and low manufacturing cost;
- Fully enclosed conveying with good dust sealing;
- Multiple feed and discharge points can be arranged;
- Suitable for medium- and short-distance conveying of powdery, granular and small-lump materials.
Disadvantages:
- Relatively high wear of the flights and the trough;
- Not suitable for sticky, easily caked, highly abrasive, or large-lump materials;
- Limited conveying distance and capacity.
7. Typical Applications
Screw conveyors are widely used in grain and feed, cement and fly ash, chemical raw materials, environmental protection (sludge and solid waste), food processing, mining and beneficiation, and other industries.
Post time: Sep-21-2026