The spiral hopper, also known as a spiral feeder, spiral conveyor bin, or pre-feeding device, is a crucial automatic feeding and pre-processing unit at the front end of a metal scrap baler (or metal scrap packer). Its main function is to continuously, stably, and controllably transport loose, irregular, and bulky metal scraps (such as steel scraps, aluminum scraps, copper scraps, cast iron scraps, etc.) into the mold cavity of the main pressing mechanism, laying the foundation for efficient baling.

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Core Functions and Importance

1. Automatic Continuous Feeding: Replaces manual shoveling, automating the production process, significantly improving efficiency, and reducing labor intensity.

2. Pre-compression and Densification: During conveying, the spiral blades initially compress and expel air from the loose metal scraps, increasing the material density and making the material entering the main pressing mold cavity more uniform and compact. This helps improve the density and forming quality of the final baler (bread), and reduces the impact load on the main pressing cylinder.

3. Uniform and Stable Feeding: By controlling the screw speed (usually controlled by a frequency converter), the amount and speed of material delivered to the main pressing cavity can be precisely adjusted, ensuring a stable pressing process and avoiding "material spraying" or insufficient feeding, thus guaranteeing the consistency of cake weight and size.

4. Arch Breaking and Anti-Blocking: For fine or poorly flowing metal shavings (such as cast iron shavings), the screw device in the storage hopper effectively breaks the "bridging" phenomenon formed by the material, ensuring smooth material flow and preventing hopper blockage.

5. Storage and Buffering: The upper conical or square hopper has a certain capacity to temporarily store a certain amount of metal shavings, providing a buffer between upstream processing (such as crushing and magnetic separation) and subsequent cake pressing, making the production line run more smoothly.

Main Structure and Components

A typical spiral hopper usually includes the following parts:

Hopper Body: The upper part is a large-volume storage bin, often square or conical in shape, welded from thick steel plates. The inner wall is smooth or lined with plates (such as wear-resistant steel plates or high-molecular-weight polyethylene plates) to reduce friction and adhesion.

Screw Conveyor Shaft: The core component, a robust steel shaft with continuous spiral blades welded on it. The blades are designed according to the material characteristics, usually solid, thick, and wear-resistant.

Drive Unit: Includes a geared motor (commonly a gear reducer or worm gear reducer) and a frequency converter. The frequency converter is used for stepless speed regulation to precisely control the feed rate.

Bearing Housings and Seals: Support the two ends of the spiral shaft and equipped with good seals (such as labyrinth seals, packing seals, or mechanical seals) to prevent fine metal dust from entering the bearings and extend the equipment's lifespan.

Discharge Port: Connects to the inlet of the main pressing cavity of the briquetting machine. It is usually designed with an adjustable gate or valve to open and close in conjunction with the briquetting cycle.

Protective and safety devices: including inspection covers, safety guards, and overload protection devices (such as safety pins or torque limiters).

Work Process

1. Metal shavings are fed into the hopper above the screw hopper via a crane, conveyor belt, or manually.

2. The operator starts the equipment and sets or adjusts the screw conveyor speed.

3. The geared motor drives the screw shaft to rotate, and the screw blades push and compress the metal shavings at the bottom of the hopper forward (towards the discharge port).

4. The initially compressed metal shavings fall evenly and continuously from the discharge port into the die cavity of the pressing machine below.

5. When the main press begins pressing, the screw may pause or run at a low speed to avoid interference; after pressing is complete, the screw restarts feeding, and the cycle continues.

Processing Capacity: Must match the tonnage and production cycle of the briquetting machine, usually measured in cubic meters per hour or tons per hour.

Screw Diameter and Power: Determined based on the type of material (steel chips are heavier and more wear-resistant than aluminum chips), conveying volume, and conveying distance (hopper length).

Wear Resistance: When processing steel chips, the screw blades, shaft, and inner wall of the hopper must be made of highly wear-resistant materials or undergo hardening treatment (such as welding a wear-resistant layer).

Anti-jamming design: For long, coiled steel scraps, the auger and feed inlet require special design to prevent entanglement.

Control system: Linked with the main PLC, achieving fully automatic cyclic control.

The auger hopper is far more than a simple "funnel"; it is the key pre-processing hub for modern metal scrap briquetting machines to achieve efficient, automatic, stable, and high-yield production. Its performance directly affects the overall working efficiency of the briquetting machine, the quality of the briquettes, and the reliability of equipment operation. Therefore, when purchasing a briquetting machine, equipping it with a well-designed, robust, and durable auger hopper is crucial.