Feb 23, 2021
The following methods of calender roll removal are recommended by Valmet. Other methods may be used, depending on the style and size of calender and the lifting equipment available at the mill.
Before attempting to remove a roll, make certain that all air, steam, water and lubrication hoses are disconnected from the roll and outboard doctor.
Unbolt the outboard doctor and remove with the overhead crane. Place the doctor carefully on the floor supported by blocks at each end and with the holder pointed up.
If all the rolls of a calender stack are being removed, start at the top roll and remove one at a time. When removing one roll from within the stack, activate the roll lift unit and separate the rolls to the maximum. This will provide clearance for removal.
An overhead crane with two or three hooks is the recommended equipment for calender roll removal, As illustrated in the following procedures, the overhead crane may be attached to the roll with a roll removal lift bar, a sling around the journal or a sling around one end of the roll.
CAUTION: Regardless of how the crane is attached to the roll, the bolt (possibly 2) which attaches the bearing housing to the roll arm should not be removed until the roll is firmly held by the overhead crane. Do not remove bolts from a roll other than the one being held by the overhead crane. Rolls not supported by the crane could cause bodily injury to personnel working near the stack if accidentally bumped off the roll arm. |
Secure the housing to the lift hook (Figure 1) or lift the roll slowly allowing the housing to rotate to a balanced position.
CAUTION: The unbalanced weight of the calender bearing housing may cause bodily injury if allowed to rotate suddenly after being lifted out of the stack. |
Figure 2 shows the calender roll being removed with roll removal lift bars. No overhead framing interferes with removal from the stack.
This method is an alternate which can be used on a calender stack as shown in Figure 2, Instead of roll removal lift bars, wire rope slings attached to an overhead crane and come-a-longs are used for lifting the roll.
Figure 4 illustrates a calender stack where overhead framing is present but is designed especially to allow rolls to be removed out and up from the stack. An overhead crane is attached to the roll as described in either method 1 or 2. The roll is lifted vertically out of the overhead framing and lowered onto prepared blocks.
Figure 5 illustrates a calender stack in which the overhead framing prevents the roll from being removed from the stack in one operation. An overhead crane (or cranes) with three hooks is recommended for this removal operation.
For more assistance with your calender operation and maintenance, contact your Valmet representative.