Loading and Unloading Tires Hydraulic Cylinder for Vulcanizing Machine

Soft Tire In.
Hot Tire Out.
Same Cylinder. Different Grip.

Every other vulcanizing cylinder works on the mold or the centre mechanism — steel components at known positions and known weights. The loading/unloading cylinder is the only one that handles the tire itself — swinging the loader arm in to grab it, lifting it, and swinging it out. Going in: a soft, sticky green tire that deforms if gripped too hard. Coming out: a stiff, 180 °C cured tire that burns anything it touches. Every second of this transfer is a second the press sits idle.

Every Second Counts — The Loader Arm Sets the Production Rate

A typical passenger car tire cure cycle is 10–15 minutes. The mold open → unload → load → mold close sequence adds 30–90 seconds to every cycle — time during which the press produces nothing and the mold loses heat. The loading/unloading cylinder's speed directly controls how much of that dead time the loader arm consumes.

The loader arm is not a simple linear pusher — it is a multi-axis mechanism that must position the tire precisely in 3D space. The loading/unloading cylinder typically provides one axis of this motion (the horizontal swing or the vertical lift), while separate cylinders or pneumatic actuators handle the other axes (grip open/close, secondary lift, rotation).

The 2,000 mm stroke accommodates the full swing arc from the staging conveyor (outside the press frame) to the mold centre (inside the press frame) — a distance that spans the press's platen width plus the clearance needed for the loader arm to clear the tie bars or the dome structure. On large presses, this swing distance can approach 2 metres.

The cylinder must coordinate with the mold opening/closing cylinder (#30): the loader arm can only swing in after the dome is fully raised, and must swing out before the dome begins lowering. These interlocks are sequenced by the press controller — the loading/unloading cylinder's position sensor confirms "arm clear" before the dome descent is permitted.

The 63–100 mm bore with ≤2,000 mm stroke creates a slender cylinder that must resist lateral loading from the cantilevered loader arm. The loader arm's weight (plus the tire) applies a bending moment at the cylinder rod end — which translates to a side load on the rod guide bearing. Korea Ever-Power specifies an oversized guide bearing length for the loading/unloading cylinder — longer than standard for a 63–100 mm bore — to distribute this side load and prevent eccentric seal wear.

The cylinder operates in the thermal zone between the hot open mold (below) and the warm press frame (around) — ambient temperature 40–80 °C at the cylinder's mounting position. FKM seals are standard. Chrome plating is 50 µm. The bore is honed to Ra 0.2–0.4 µm over the full 2,000 mm stroke. End-of-stroke cushions at both positions (swing-in and swing-out) prevent impact loads on the loader arm stops.

Every loading/unloading cylinder is hydrostatic tested at 1.5× working pressure and speed-tested for full extend and retract at the specified cycle time — verifying that the cylinder completes the full 2,000 mm stroke within the press builder's target loader arm cycle time.