How to adjust the blade angle of a mine-used axial flow fan?
Mine-used axial-flow fans (such as K and DK series) have their blade angles manually adjustable during shutdown. The core process is as follows: power-off shutdown → remove cover plate / open observation window → loosen nuts → align the blade angle with the hub scale → symmetrically tighten → recheck → test operation.
I. Preparation before adjusting the mine-used axial-flow fan (Safety First)
Shut down and power off: Cut off the main power supply of the fan, hang a “Do not close the switch, work in progress” warning sign, and follow the procedures of power-off, voltage check, discharge,挂牌， and locking.
Determine the target angle： Refer to the fan performance curve， combined with the mine’s air volume and negative pressure requirements， select the blade installation angle (usually ±1° to ±2° for fine-tuning).
Tools and protection： Prepare a special wrench， angle ruler， torque wrench， wooden hammer， and wear a safety helmet， gloves， and goggles.
Space preparation： For the rotary fan， disassemble the first and second-level connections， and pull apart a distance of ≥80cm； for single-stage fans， open the hub cover / observation window.
II. Standard adjustment steps for mine-used axial-flow fans (taking FBCDZ/FBCZ as an example)
Remove cover plate / open observation window： Remove the hub end cover or open the machine shell observation window to expose the blade root and the adjusting nut.
Loosen the blade nut： Use a special wrench to symmetrically loosen the nut at the blade root (each side loosen 3 to 4 turns， do not fully loosen)， and use a wooden hammer to gently tap the blade top to make it loose.
Align the scale and adjust the angle： According to the angle scale / positioning hole (0°， ±1°， ±2°…)， align the blade back edge tail edge with the target scale； all blade angles must be consistent， with a deviation of ≤±0.5°.
Symmetrical tightening： Tighten the nuts in a diagonal sequence using a torque wrench， reaching the manufacturer’s specified torque； lock the anti-loosening part (such as stop washers).
Recheck and cleaning： Check the angle of each blade one by one， clean the flow passage of tools / debris； reinstall the cover plate and connect the fan.
Test operation and monitoring： After manual rotation without obstruction， power on and start； monitor air volume， air pressure， motor current， vibration， and temperature， ensuring they are within the rated range.
III. Relationship between the angle of the mine-used axial-flow fan and operating conditions
Angle ↑： Air volume ↑， air pressure ↑， motor power ↑ (easily overloaded).
Angle ↓： Air volume ↓， air pressure ↓， motor power ↓.
After each adjustment， it is necessary to check that the motor current ≤ rated value；严禁 operating beyond the power limit.
IV. Key precautions for mine-used axial-flow fans
Safety red line： Must perform shutdown and power-off operations；严禁 operating / running while adjusting the angle.
Consistent angle： All blade angles must be the same； otherwise， the impeller will be unbalanced， vibration will exceed the limit， and the bearings will be damaged.
Torque compliance： Tighten according to the manufacturer’s requirements， preventing loosening or over-tightening.
Prevent overload： Focus on monitoring the motor current after increasing the angle； if the current exceeds the limit， immediately stop and adjust back.
Lubrication and rust prevention： Apply lubricating grease at the nut after adjustment to facilitate the next operation.
Record and archive： Record the angle， air volume， air pressure， and current before and after adjustment， and establish a ledger.
V. Common problems and handling of mine-used axial-flow fans
Blade jamming： After loosening the nut 3 to 4 turns， use a wooden hammer to gently tap， and if still jammed， check the mating surface of the blade handle and hub， remove rust， apply lubricating grease， and then adjust.
Large angle deviation： Re-loosen the nut， align each blade with the scale one by one， use an angle ruler to recheck， and ensure consistency.
Excessive starting current： Immediately stop， reduce the blade angle， and try again.
