Shaftless Screw Conveyor

Shaftless Screw Conveyor

The shaftless screw conveyor is an industrial conveying device that abandons the traditional central shaft design. It employs a shaftless screw body as its core conveying component, driven by an electric motor to rotate the screw body. This continuously pushes materials along a closed U-shaped/O-shaped trough.

It fundamentally addresses the common issues of entanglement and blockage found in traditional shaft-type conveyors, making it particularly suitable for handling paste-like, viscous, fibrous, or lumpy materials (such as sludge, waste pulp, slag, municipal solid waste, etc.). It combines sealed environmental protection, compact structure, and easy maintenance, finding extensive application in environmental protection, chemical, mining, food, and other industries.

Shaftless screw conveyors are categorized into single shaftless screw conveyors and double shaftless screwconveyors.

Single-shaft screw conveyor—composed of a single screw body, lacking mixing or stirring capabilities.

Double-shaft screw conveyor—composed of two screw bodies with counter-rotating screw blades to prevent material jamming. It offers 1.5 to 2 times the conveying capacity of a single-shaft conveyor and ca simultaneously perform conveying, mixing, and stirring functions.

Structural Components

The shaftless screw conveyor primarily consists of a drive unit, head assembly, housing, shaftless screw element, trough liner plates, inlet, outlet, cover (if required), and base.

Drive Unit: Utilizes a cycloidal pinwheel reducer or shaft-mounted hardened gear reducer. Design should prioritize positioning the drive unit at the discharge end to maintain the screw shaft in tension during operation. The drive unit should be located as close as possible to the material outlet. Its protection rating is typically IP65.

The head assembly incorporates thrust bearings to withstand axial forces generated during material conveyance. Thrust bearings: Installed at the head to bear axial forces during material transport, preventing backward slippage of the screw shaft. Thrust bearings have a service life of no less than 100,000 hours, ensuring long-term stable operation.

Housing: Available in U-shaped or O-shaped configurations, featuring a rainproof cover on the upper section. Materials include stainless steel, carbon steel, or fiberglass-reinforced plastic (FRP).

Shaftless Screw: Constructed from stainless steel or carbon steel. Screw blades have a minimum thickness of 20mm to ensure adequate strength and durability. The blade height is no less than 80mm, enabling efficient material conveyance to the destination.

Trough Lining Plates: Installed on the outer surface of the screw body to prevent friction wear between material and screw. Made of wear-resistant plastic, rubber, or cast stone plates.

Inlet/Outlet Ports: Available in square or round configurations, with the specific form typically determined by the user.

Working Principle

The shaftless screw conveyor operates by an electric motor driving a cycloidal reducer. The screw rotates through mechanical seal shafts connected to the drive discs on the shaftless screw body. Sludge discharged into the inlet at the top of the U-shaped trough is conveyed by the screw mechanism and discharged through the outlet at the bottom of the U-shaped trough.

Product Advantages

Strong Anti-Wrapping Performance: Compared to shafted screw conveyors, shaftless screw conveyors lack intermediate bearings. This design offers distinct advantages when handling strip-shaped, viscous, or easily entangled materials, effectively preventing material blockages.

High Conveying Capacity: Shaftless screw conveyors deliver torque up to 4000 N·m, significantly exceeding shafted models. Their conveying capacity reaches 1.5 times that of shafted conveyors.

Long Conveying Distance: A single unit can convey materials up to 60 meters. Shaftless screw conveyors enable extended conveying distances and support multi-stage series installation based on user requirements.

Excellent Sealing: Trough covers with appropriate gaskets ensure odor-free operation and form a barrier preventing atmospheric ingress. This guarantees environmental hygiene, prevents material contamination and odor leakage, and maintains sanitary conveying conditions.

Flexible operation: Supports single-point or multi-point feeding with adaptable discharge configurations—either bottom or end discharge—suiting diverse production scenarios to enhance efficiency and flexibility.

Extended service life: Utilizes specialized plastic, rubber, or cast stone plates to eliminate direct friction between blades and housing. Superior wear resistance prolongs equipment lifespan, reduces maintenance costs, and boosts production profitability.

Application Areas

The shaftless screw conveyor employs a shaftless design for handling municipal solid waste, screened materials and floating solids, dewatered, thickened, or conditioned sludge, packaged foodstuffs, creams or pastes, as well as waste generated during meat, fish, fruit, and vegetable processing. Primary application areas include: wastewater treatment, sugar mill waste, fish processing, solid waste management, fruit and vegetable processing plants, beverage industry, pulp and paper manufacturing, chemical industry, general food processing, meat processing plants, slaughterhouses/abattoirs, restaurants, cafeterias, and general food service.

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