Cone Crusher Product

Overview

A cone crusher is a secondary or tertiary crushing machine that reduces pre-crushed stone (50–200 mm) into smaller, more cubical aggregate (10–30 mm). Unlike jaw crushers, which compress material between fixed and moving plates, cone crushers rotate a cone-shaped mantle inside a fixed concave bowl. This eccentric rotation creates a continuous crushing cavity that circles the mantle, producing uniform, shaped aggregate suitable for concrete and asphalt. Cone crushers are favored for secondary crushing because they produce less fines (dust) and more cubical product than impact crushers.

How it works

Stone fed into the hopper falls into the crushing cavity, the space between the rotating mantle cone and the fixed concave bowl. An eccentric shaft, driven by an electric motor through a gearbox, imparts an off-center rotating motion to the mantle. As the mantle rotates eccentrically, it moves inward (compressing material against the concave) and outward (releasing material toward the discharge). This cycle repeats 600–1800 times per minute (depending on gearbox reduction).

The eccentric motion ensures that all material in the cavity is crushed: stones near the bottom of the cavity receive multiple compression cycles as the mantle rotates, while stones near the top exit toward the discharge opening. The hydraulic system automatically maintains cavity size—as liners wear, hydraulic cylinders push the bowl outward slightly, keeping the discharge opening constant. An overload relief valve protects the machine if an un-crushable object enters the cavity.

Components and subsystems

Crusher Frame

The main structure consists of a fixed outer bowl (cast steel or fabricated) and an inner bowl containing the fixed concave surface. The bowl is supported on four legs or channels and incorporates spring dampers around the upper frame. These springs allow the mantle to oscillate freely and reduce vibration transmission to the foundation. The concave surface is bolted to the inner bowl and is replaceable, typically lasting 1000–2000 hours of operation.

Rotating Mantle

A cone-shaped rotating element (1–1.5 m height) that forms one surface of the crushing cavity. The mantle is forged or cast steel with replaceable manganese-steel liners bolted to the outer surface. As material is crushed, liners gradually wear and must be changed. Modern mantles can be exchanged in 2–4 hours by removing a few dozen bolts and sliding the new assembly into place.

Fixed Concave Surface

The fixed inner surface of the bowl, also manganese-steel and replaceable. The concave and mantle liners work together to define the crushing cavity geometry. As both wear, they must be replaced in coordinated sets to maintain proper cavity shape and clearance.

Eccentric Shaft and Bearing

The heart of the drive mechanism. A forged alloy steel shaft (60–120 mm diameter) rotates on a large spherical roller bearing. The shaft has an eccentric portion (30–50 mm throw), creating the off-center rotation. As the shaft rotates at 600–1800 rpm, the mantle traces a complex path: it rotates and moves in and out, compressing material throughout the crushing cavity. Oil-cooled seals prevent lubrication from escaping.

Hydraulic System

A proportional hydraulic system automatically adjusts the cavity size and protects against overload. As mantle and concave liners wear, hydraulic cylinders beneath the bowl push outward slowly, maintaining a constant discharge opening. A pilot-operated relief valve monitors system pressure; if pressure exceeds a setpoint (typically 150–200 bar, indicating a stuck or un-crushable object), the relief valve opens, allowing the mantle to move back and the object to be ejected. This hydraulic protection eliminates the need to manually shut down the machine when a large tramp iron or concrete fragment enters.

Drive Motor Assembly

A three-phase AC electric motor (30–90 kW, 900–1500 rpm) provides the input power. This is connected via a flexible coupling to a gearbox (planetary or helical reducer, 4:1–10:1 ratio), which increases torque and reduces speed to match the required eccentric shaft rotations. The gearbox is coupled directly to the eccentric shaft via a second coupling.

Hopper and Feeder

A large receiver bin (5–15 ton capacity) feeds stone to the cavity. A distributor ring (sometimes rotating) spreads incoming material around the mantle circumference, ensuring even feed distribution and preventing bridging. The chute is tapered to guide material into the cavity center.

Discharge Conveyor

A heavy-duty belt conveyor (0.8–1.2 m wide, 20–40 m long) removes crushed product from the discharge chute. Because cone crusher discharge consists of angular, hard material with high kinetic energy, the conveyor must be robust with impact-rated idlers and strong support frames.

Engineering considerations

Cavity geometry and gradation: The shape of the crushing cavity (formed by the mantle and concave) determines product shape. A steep cavity (narrow angle) produces coarse, blocky product with less fines; a gentler cavity produces finer product with more dust. Operators adjust this by selecting appropriate mantle-concave combinations and discharge settings.

Hydraulic adjustment: The automatic cavity adjustment system is a major advantage over jaw crushers. As liners wear, the machine maintains discharge size automatically, improving product consistency and extending liner life. When liners become too thin (near breakthrough), operators replace both mantle and concave in a coordinated maintenance event.

Fines generation: Cone crushers generate fewer fines than impact crushers but more than jaw crushers. The cyclic compression and grinding action produces more dust (particles <1 mm) than would be ideal, especially with soft or friable stone. Wet material fines are often recycled back to the feed.

Product shape: The eccentric rotating motion and multi-pass compression produce highly cubical (shaped) aggregate, preferred for concrete strength and paving. Jaw crushers produce more irregular slabby particles; impact crushers produce very angular but less uniform shapes.

Throughput and speed: Higher rotational speeds increase throughput but also increase wear and vibration. Most cone crushers operate at 600–1200 rpm for secondary duty (finer product) or 1200–1800 rpm for coarser duty. Some designs use variable-speed gearboxes to allow operators to adjust throughput and product size simultaneously.

Vibration and noise: Cone crushers generate rhythmic vibration at the operating frequency (10–30 Hz). Foundation design must account for this, typically requiring a dedicated concrete pad with isolation springs. Sound pressure levels are 90–100 dB, requiring noise barriers or enclosures in populated areas.

Overload protection: The hydraulic relief system is critical for field reliability. A jam-up (hard, un-crushable object) triggers the relief valve, allowing the crusher to eject the object and continue operating without shutdown. This contrasts with jaw crushers, where a jam requires stopping and manual removal.