Roller problems in a rubber open mixing mill can affect production efficiency and equipment reliability. Common faults include bearing overheating, incorrect roll gap adjustment, inaccurate gap settings, and sudden roller stoppage. The appropriate corrective action depends on the cause of the fault.
1. Roller bearing temperature exceeds 100°C
Excessive temperature around the roller bearings may result from insufficient lubrication, inadequate cooling, excessive material loading, or wear on the journal and bearing bush.
Possible causes and corrective actions
Excessive feed and low roller surface temperature
When the roller surface temperature is below the process requirement and too much material is fed into the mill, the bearing load may increase. The resulting load can disrupt the lubricating oil film, leaving the bearing bush's loaded surface inadequately lubricated. Friction then generates excess heat.
Stop feeding the material and raise the roller surface temperature to the required process setting. Once the temperature is within the specified range, reduce the feed quantity.
Insufficient lubrication pressure or oil supply
Low oil supply pressure, insufficient lubricant flow, or a blocked oil line can prevent the bearing from receiving adequate lubrication.
Stop the machine and inspect the lubrication system. Check the oil supply, pressure, and delivery lines, and clear any blockage before restarting.
Inadequate cooling water flow
Restricted cooling water circulation or insufficient flow can cause the bearing housing temperature to rise.
Increase the cooling water flow as required, and inspect the circulation lines for blockages or other restrictions.
Severe wear on the roller journal or bearing bush
A worn roller journal or bearing bush may develop rough sliding surfaces, increasing friction and operating temperature.
Stop the machine and inspect both contact surfaces. Repair and polish the worn surfaces where feasible, or replace the bearing bush if the damage cannot be corrected adequately.
2. The roll gap cannot be reduced
If the distance between the two roller working surfaces cannot be adjusted to the required minimum, inspect the roller dimensions and bearing bushes.
Possible causes and corrective actions
Excessive reduction in roller diameter
If the roller working surface has been ground down too far, the speed ratio gears may interfere during meshing. Correct the interference by adjusting the gear tooth tip height according to the machine's design requirements.
Excessive bearing bush wear
A severely worn bearing bush may have an excessively large internal bore, affecting the roller's position and adjustment range.
Inspect the bearing bush and replace it if the bore exceeds the allowable dimensions.
3. The roll gap setting is inaccurate
An inaccurate roll gap can affect processing conditions and the thickness of the rubber compound. The adjustment mechanism should be checked for wear or damage.
Possible causes and corrective actions
Worn or damaged safety shim
The safety shim in the roll gap adjustment mechanism may become worn or damaged, affecting the accuracy of the setting.
Inspect the shim and repair or replace it as required.
Worn adjustment screw or nut
Severe wear on the adjustment screw or nut can cause excessive clearance and make the roll gap difficult to control accurately.
Inspect the threaded components and repair or replace any parts that are excessively worn.
4. A roller suddenly stops rotating
A roller that stops unexpectedly may indicate excessive loading, unsuitable processing temperature, excessive feed, or bearing seizure.
Possible causes and corrective actions
Roll gap is too narrow
An excessively narrow gap can place an excessive load on the rollers and drive system, causing the rollers to stop.
Increase the roll gap as required, then check the machine for damage or other causes of overload before resuming operation.
Roller surface temperature is too low
When the roller surface is too cold, the rubber compound may be difficult to process, increasing the load on the rollers.
Remove the remaining material from the roller surfaces after safely stopping the machine. Continue heating the rollers until they reach the required process temperature before feeding material again.
Excessive feed quantity
Feeding too much material at once can overload the rollers and drive system.
Reduce the feed quantity and follow the recommended loading procedure for the machine.
Insufficient lubrication and bearing seizure
If the roller bearings receive insufficient lubricant, the roller journal and bearing bush may seize due to excessive friction.
Stop the machine immediately. Remove the bearing housing for inspection and assess the condition of the journal and bearing bush. Repair and polish the contact surfaces where appropriate, or replace the damaged components before restarting the machine.
5. Custom machining for open mixing mill components
When roller faults result in severe wear or damage to mechanical components, repair or replacement may be necessary. Hansheng Automation can assess custom machining for suitable shafts, bearing related components, and other non-standard metal parts according to customer drawings, material specifications, and dimensional requirements.
Our precision machining services also cover components for rubber processing equipment, tobacco packaging machinery, and filling machinery. We can assess custom parts for yacht equipment and RC racing cars based on the supplied drawings and machining requirements.
