Jan 21, 2020
Check the screws of screw connections and mounting bolts for appropriate torques. The torques must be as specified. If a screw connection has slipped, open the screw connection, clean the joint surfaces, change the screws and reinstall the connection.
Checking is also recommended when increasing the machine speed, the masses or the loads from the initial values. Check the condition of the screw couplings also after exceptionally heavy loading (e.g. if a roll explodes).
The critical welded seams of the reel should be inspected after 20 years using magnetic particle technique and ultrasonic inspection. Check the structure for fatigue cracks on the weld surface and on the back of weld. Effective throat thickness of the design weld should be found in the structure undamaged. Repair any damaged welds.
Checking is also recommended when increasing the machine speed, the masses or the loads from the initial values. The mechanical structures of the machine are designed to bear specific loads, speed and masses, which must not be exceeded. The increased loads substantially shorten the service life of the mechanical structures of the machine.
The reel has mechanical parts which wear down in daily use. Check and service the wearing parts regularly to ensure flawless operation of the machine.
The hydraulic and pneumatic actuators of the reel, such as the cylinders, must be checked and, if necessary, serviced or replaced at regular intervals. The most common fault in these actuators is wear of the piston and piston rod seals, causing leakage in the cylinder.
Remember to protect the cylinders if someone is welding or grinding, etc. in the vicinity in order to avoid damage to the rod or seals.
Replacing the seals is a fairly simple procedure but it requires removing the cylinder from the machine, i.e. a shutdown. Normally, mills have spare cylinders for important positions, so all that is needed during shutdown is replacement of the cylinder. The cylinder removed from the machine is then overhauled after the shutdown and stored for the next replacement instance.
For assistance with maintenance and optimization of your reel, contact your Valmet representative.