Maintenance of finishing mill roll boxes

The roller box is a closed reduction gear box mechanism, and the maintenance requirements are strict, especially for oil sealing, dustproof and waterproof. The roller box has 3 shafts as the key points of sealing, and the sealing requirements are strict, so the mechanical seal and the skeleton seal are installed in pairs.
 

Maintenance inspection content
1. Check whether the roller shaft moves in the axial direction. The roller ring can be pryed with a wrench.
2. Check whether the connection bolts are loose, the sealing cover, the adjustment box tile, the short shaft coupling bolts, etc.
3. Check whether the oil inlet and water inlet pipes are loose. Whether the aluminum wire is tightly bound. If the oil inlet pipe falls off, it will burn the box, and if the water inlet pipe falls off, it will collapse and affect the product quality.
4. Check the oil and gas and seal wear of the roller box.
5. Check whether the glasses plate is worn or not. The guide wheel wears out the glasses plate and can be repaired with 528 glue.
6. Check whether the position of the vent hole is correct, otherwise it will cause water ingress.
7. Visually check whether the oil pressure, water pressure and prestress are normal.
8. Regularly refuel the axial adjustment lock nut. (Twice a week) Otherwise, it will bring inconvenience to the post personnel to adjust the roller wrongly.
9. Regularly clean the water jacket of the finishing mill. (one month)
10. When shunting or crawling, listen to the sound inside the roller box for any abnormality.
11. It is planned to replace the seal within 20 days of maintenance.
12. Understand the online use of the roller box with the post workers. Whether there is a change in the roll gap, whether there is abnormal sound, whether there is abnormal temperature, and whether there is roll swing.

Common faults and treatment methods of roller boxes
When the roller box fails, it is often the post personnel who find it first. For example, during maintenance during the shift, if the post personnel pay attention to the temperature of the roller box or pay attention to the sound of the roller box when turning the car, they will also find the failure of the roller box. In general, the faults that occur after the in-shift maintenance and start-up can be found during the in-shift maintenance. If you pay attention to the high temperature of the roller shaft, the roller shaking, the abnormal sound, and the change of the roller gap, etc.
1. Shaft channeling. Check that the axial movement is greater than 0.05mm, and replace the roller box immediately.
2. Beating teeth: The roller box vibrates greatly, and there is a rhythmic rattling sound in the box when crawling or when turning the car at 200 rpm, and the roller box should be replaced immediately.
3. Sintering box: smoke is emitted from the exhaust hole, and the temperature of the shaft head is very high, which is obviously different from other roller boxes, and should be replaced immediately.
4. Shaft breakage: steel stacking, serious roll error, roll box roll gap change, shaft does not rotate when crawling. Replace immediately.
 

5. The roll gap of the roll box cannot be adjusted: if the set roll gap cannot be adjusted, replace it immediately. The reason is that the oblique iron screw is stuck and the screw buckle is damaged. At present, there are three reasons that can cause this phenomenon: when the prestress is not lowered, the roller box is adjusted, and the lead screw is stuck; when the roller gap reaches the large and small positions, the lead screw is blocked; die.
6. Roller shaking: turn the car to hit the meter, hit the bottom of the roller groove first and then hit the roller shaft. If the coaxiality of the roller shaft is below 0.05mm, re-install the roller. If the coaxiality of the roller is more than 0.05mm, the roller is bent or the bearing is faulty, and the roller box should be replaced immediately.
7. Prestressed pressure relief: confirm the pressure or open the oil discharge hole to check and confirm and replace it.
8. Broken shaft journal sleeve: It is difficult to check it out at present, and it is necessary to measure the shaft head regularly to avoid some accidents. Shattered journal bushings may cause scorching and denting. Pay attention to the details of installing the roller ring. If it is found that the roll is not pressed during maintenance, notify the maintenance workshop to check the journal sleeve and roll diameter seal to prevent failure.
9. Grinding and sealing: the roller ring is not pressed; the journal sleeve is broken; if it is the upper roller shaft, the adjustment may be too low or the adjustment lock nut is not locked, causing the roller box to drop; the roller ring is biased.
10. The size of the finished product fluctuates: it is not easy to judge online. Replaceable roll box.
11. Oil film shedding and roller shedding: It is difficult to detect this phenomenon. The shedding of the inner surface of the oil film bearing can be checked by measuring the axial and radial clearance of the roller box. It is required to measure the axial and radial clearances of the roll box one by one during maintenance, and the radial clearance is required to be 0.24-0.35mm and the axial clearance to be within 0.03mm.