Cement Equipment Vertical Mill Cylinder

Same Spec Sheet.
Different Machine.
Different Engineering.

Bore 200–700 mm. Thrust up to 5,387 KN. Stroke ≤500 mm. Pressure 14 MPa. These numbers are identical to the roller press cylinder (#20). But this cylinder operates on a vertical roller mill — where the force direction, the grinding geometry, the lever mechanism, and the dual push/lift requirement are all fundamentally different.

The vertical mill cylinder is typically mounted horizontally or at a shallow angle on the mill housing — not vertically above the roller. The force conversion from horizontal to vertical happens through a rocker arm: a heavy steel lever that pivots on a bearing mounted on the mill body.

The cylinder rod connects to one end of the rocker arm. The grinding roller shaft connects to the other end. The pivot is between them. When the cylinder extends, it pushes the rocker arm upward at the cylinder end — which pushes the roller end downward onto the grinding table. The lever ratio (distance from pivot to cylinder attachment ÷ distance from pivot to roller shaft) determines the force multiplication: a 2:1 ratio means the cylinder's 5,387 KN produces 10,774 KN of vertical grinding force on the roller.

This rocker arm mechanism is unique to the vertical mill — the roller press cylinder (#20) pushes the movable roller directly, without any lever mechanism. The rocker arm adds complexity (an additional pivot bearing, a structural lever arm) but provides force multiplication that allows a smaller cylinder to produce the same grinding force — or the same cylinder to produce significantly more grinding force than the roller press at the same pressure.

Dual Function — Push Down to Grind, Pull Up to Lift

The roller press cylinder only needs to push — retraction simply relieves the grinding force, and the rollers stay in contact with the material by gravity. The vertical mill cylinder must do both: push the rollers down for grinding AND pull the rollers up off the table — a retraction function that the roller press never needs.

This dual push/pull requirement means the vertical mill cylinder must generate meaningful force in both directions — the retraction force (rod-side annular area × pressure) must be enough to lift the roller, the rocker arm, and overcome the roller's weight component on the rocker geometry. Korea Ever-Power verifies both extend and retract forces during the engineering phase. Contact the hydraulic cylinder engineering team for vertical mill cylinder specifications.

On a roller press (#20), the material enters the nip between two rollers from above, in a controlled stream. On a vertical mill, the material is spread across a rotating table by centrifugal force — creating a material bed that is thicker near the centre (where the feed drops) and thinner near the dam ring at the outer edge (where the ground material overflows). The rollers grind the material as the table sweeps it beneath them.

This non-uniform bed creates load variations that the vertical mill cylinder must absorb. As the table rotates, each roller encounters alternating thick and thin zones — the cylinder must compress and extend rhythmically as the material bed thickness varies under the roller. This oscillating load is typically at the table rotation frequency (10–30 RPM) — slower than the roller press vibration but larger in amplitude (10–30 mm of roller travel per revolution).

The nitrogen accumulator absorbs these oscillations — compressing as the thick zone passes under the roller (roller lifts, cylinder retracts slightly) and expanding as the thin zone passes (roller drops, cylinder extends slightly). Without the accumulator, the pressure spikes on the thick zone would overstress the cylinder and the rocker arm bearings.