DZ-22 Reducing Mill

Precautions.

1. Condensation can form on the contactors when humidity changes — take measures to prevent phase-to-phase short circuits.
2. Keep the machine clean, especially the dirt between incoming and outgoing phases.
3. Inspect, service and maintain the machine regularly.
4. Carry out a full overhaul every 5,000 operating hours.
5. Check all fasteners for looseness regularly.
6. Stop the machine if it makes an abnormal noise, find the fault, then restart.
7. Replace the die when wear causes bent or out-of-tolerance reduced ends.

Applications and features. This is a chipless machine: hydraulic force pushes the part into a dedicated die and it is cold-reduced in one stroke. Output is high, operation is simple, material is saved and quality is consistent. The reduced section becomes denser, so compressive strength rises while plasticity and impact toughness are retained. It compresses 3–5 parts per minute, 3–5 times faster than turning, and 2,000–3,000 pieces per shift — well suited to volume production. After reducing, diameter, roundness and taper errors stay within 0.03 mm, surface finish reaches Ra 1.6 or better, and parts can be extended 10–15% in length, saving material: a 20 mm bar at 864,000 pieces a year saves about 30 tonnes of steel.

Installation and adjustment. The machine has lifting points; use a wire rope of suitable length and diameter with soft padding to protect the paint. It can stand on a level, solid floor — pour a concrete foundation where there is shock or vibration. Connect the power, check that the motor turns the right way, and set the limit switch for the required reduced length. Set hydraulic pressure as low as possible while still completing the reduction: finer work needs less pressure, and lower pressure means slower but safer operation. To change the die, loosen the front screws, remove the end cover and tap the die out from the rear with a soft wedge — never strike the carbide — then fit the new die and tighten the cover. To change clamping blocks, open the clamping cylinder cover, withdraw the two pins, swap the blocks in their numbered positions and reassemble; clean and oil the removed blocks for spares.

Troubleshooting. Pressure gauge needle vibrating — blocked oil intake, clean it. Vibration on feed or return — air in the cylinder, bleed it; or the slide is short of oil. Oil too hot — viscosity too high, feed time too long, pressure too high or ambient temperature too high; fit a cooler. Pressure will not build — worn pump, oil viscosity too low, faulty relief valve or worn coupling. Contactor humming — clean oil and rust from the core faces. Breaker tripping at start-up — short circuit, burnt motor, broken supply line or stuck push-button. Loss of leakage current — inspect the control and supply wiring above and below the contactor.