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.
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.
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.
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.
Advantages:
Disadvantages:
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.