What maintenance need to do for gearbox of conical double screw extruder?
The gearbox of Conical double screw extruder is the core component that transmits power and regulates speed. Its maintenance directly affects the stability and service life of the equipment.
Considering its working characteristics (high load, continuous operation, susceptible to dust/high temperature), Yongte recommends users to formulate the following maintenance plans for the gearbox:
Lubricant selection
1. Gear oil of the specified model (usually medium and high viscosity extreme pressure gear oil, such as 220#,320# industrial gear oil) must be used. Avoid mixing different brands or models of oil (may lead to chemical reaction and performance degradation).
2. When the ambient temperature is high (such as summer or near the heating area), oil with slightly higher viscosity (such as 320#) can be selected; 220# can be selected in low temperature environment to ensure the fluidity at startup.
Change lubricating oil regularly
1. First oil change: the new machine must be replaced after 100-200 hours of operation (metal debris will be produced during the running-in period, and the failure to replace it in time will aggravate the wear).
2. Conventional oil change cycle: according to the operation intensity, it is generally replaced every 3000-5000 hours; if the environment is dust and load is large, it is shortened to 2000-3000 hours.
3. Oil change operation:
l After stopping, wait for the oil temperature to drop to 40-50℃ (to avoid high temperature oil splash, and the hot oil flow is good, easy to drain), open the oil screw plug, completely drain the old oil (the equipment can be tilted to assist the oil discharge).
l Add a small amount of new oil to flush the interior (about 10% of the total amount), run for 1-2 minutes, then drain, and then tighten the oil release screw plug. Add new oil to the oil gauge center line according to the standard (do not overfill, otherwise it will cause oil temperature rise and leakage).
Daily oil level and oil quality inspection
1. Check the oil level gauge before starting each batch of machine. If the oil level is lower than the lower limit, replenish it in time (replenish the same type of oil, do not mix different types of oil).
2. Check the oil quality every month: if the oil color is black, cloudy, with metal fragments or odor, it indicates that the oil has deteriorated, and it should be replaced immediately (simultaneously check whether there are gear wear, bearing damage and other problems).
3. Prevent water from mixing into the oil (such as leakage of the cooling system). Water intake will lead to emulsification and failure of lubrication. The water leakage point should be replaced and repaired in time.
Temperature monitoring
1. During normal operation, the oil temperature of the reducer should be ≤60℃ (when the ambient temperature is 30℃), and if it exceeds 70℃, stop the machine for inspection:
(1) Possible reasons: too low/too high oil level, oil quality deterioration, gear meshing failure, bearing damage, excessive load, etc.
(2) Treatment: First check the oil level and oil quality, if the high temperature is still after elimination, the gear and bearing should be disassembled for inspection.
Noise and vibration monitoring
1. During normal operation, there should be no obvious abnormal sound (such as "click" or "squeak") or abnormal vibration.
2. If abnormal noise occurs, it may be gear tooth surface wear, broken teeth, bearing damage or loose installation, and the machine should be stopped immediately for inspection to avoid fault expansion.
3. Excessive vibration: Check whether the anchor bolts are loose (re-tighten to ensure horizontal installation) or whether the gear/bearing is unbalanced and needs to be calibrated or replaced.
External cleaning
Clean the oil and dust on the surface of the reducer every week (blow with high pressure air gun and wipe with wet cloth) to avoid accumulation affecting heat dissipation and facilitate observation of oil leakage points.
Seal inspection and replacement
1. Focus on checking the oil seals (skeleton oil seals) of input and output shafts, as well as the sealing pads of end covers and flanges. If oil leakage is found (oil leakage at the end of shaft, oil dripping on the joint surface), it should be dealt with in time:
l Minor oil leakage: tighten the bolt first (even force to avoid deformation of the seal due to over-tightening);
l Continuous oil leakage: stop the machine and replace the seal (select the same model of oil-resistant rubber parts, and avoid scratching the lip when installing).
2. When replacing the seal, it is necessary to clean the residual old sealant and impurities on the joint surface. If necessary, a thin layer of oil-resistant sealant (such as silicone sealant) should be applied to enhance the sealing.
Start and stop
1. Before starting, confirm that the oil level is normal. Start under no load (first open the reducer, then start the main machine to feed), so as to avoid instantaneous impact overload of the gear caused by starting under load.
2. When stopping, stop feeding first, and then stop the gearbox after the main machine is emptied to reduce the reverse torque of the gear caused by residual material.
load control
1. Overload operation is strictly prohibited (such as sudden increase of torque caused by material blockage). When the equipment is equipped with torque protector, it should be ensured that it is sensitive and effective, and the machine should be stopped in time to protect itself when overloaded.
2. Avoid frequent start-stop (especially multiple start-stop in a short time) to reduce impact wear of gears and bearings.
1. Remove the gearbox and check the gear tooth surface (whether it is slightly corroded, worn or cracked) and the tooth side clearance (if it exceeds the manual value, replace the gear).
2. Check the shaft clearance (measure with feeler gauge or instrument, too large indicates bearing wear, replace with high precision bearing of the same model).
3. Clean the internal oil channel and oil tank (prevent impurity blockage and affect lubricating oil circulation).
4. During reassembly, ensure that the gear meshing is correct (the contact spots of the tooth surface meet the requirements), the bearing preload is appropriate, and all bolts are tightened with the specified torque.
1. If the machine is stopped for more than one month, the lubricating oil should be emptied (to prevent the oil from deteriorating and corroding the metal for a long time), cleaned inside, and anti-rust oil should be applied on the surface of the gear and bearing.
2. Cover the reducer with a dust cover to avoid dust and water vapor entering, and manually turn the input shaft 1-2 times regularly (monthly) to prevent the parts from sticking together for a long time.
Through the above measures, the service life of the reducer can be effectively extended and sudden failures can be reduced. The key is "regular inspection and timely treatment" to avoid small problems accumulating into big faults (such as gear tooth breakage and bearing seizure, which may lead to the whole machine stopping for maintenance).
