Winding machine and method for controlling a second nip pressure
A winding machine for winding a finishing roll having a radius R of a sheet material on a core having a radius r c is provided. The winding machine includes: a support drum assembly arranged on a first side of the finishing roll and configured to support the finishing roll from the first side; a rider roll arranged on a second side of the finishing roll opposite to the first side and configured to apply a first nip pressure onto the finishing roll from the second side the finishing roll being supported by the support drum assembly; and a control unit configured to adaptively control the second nip pressure applied by the rider roll onto the finishing roll depending on an ascent rate of the rider roll.
1. A winding machine for winding a finishing roll having a radius R of a sheet material on a core having a radius re, comprising:
a support drum assembly arranged on a first side of the finishing roll and configured to support the finishing roll from the first side;
a rider roll arranged on a second side of the finishing roll opposite to the first side and configured to provide a second nip pressure onto the finishing roll from the second side while the finishing roll is supported by the support drum assembly; and
an adaptive control unit configured to adaptively control the second nip pressure applied by the rider roll onto the finishing roll depending on an ascent rate of the rider roll, which is proportionate to a derivative of the radius of the finishing roll.
2. The winding machine according to claim 1 , wherein the control unit is configured to calculate the rider roll ascent rate based on the radius of the finishing roll, a velocity of the sheet material with which the sheet material is fed to the finishing roll, a thickness of the sheet material and a geometry of the winding machine.
3. The winding machine according to claim 1 , wherein a first nip pressure is generated between the finishing roll and the support drum assembly by the first nip pressure and a weight of the finishing roll, and wherein the control unit is configured to adaptively control the first nip pressure to obtain a constant or slightly decreasing first nip pressure.
4. The winding machine according to claim 1 , wherein the adaptivity of the control unit is a function of the ascent rate of the rider roll.
5. The winding machine according to claim 1 , further comprising an actuator connected to the rider roll and configured to adjust the first nip pressure, wherein the actuator is operably connected to the control unit.
6. The winding machine according to claim 1 , wherein the support drum assembly is configured to feed the sheet material to the finishing roll.
7. The winding machine according to claim 1 , wherein the support drum assembly includes at least a first drum having a radius.
8. The winding machine according to claim 7 , wherein the support drum assembly includes a second drum having a radius and being arranged with a distance to the first drum.
9. The winding machine according to claim 8 , wherein the control unit is configured to calculate the ascent rate of the rider roll based on the radius of the finishing roll, a velocity of the sheet material with which the sheet material is fed to the finishing roll, a thickness of the sheet material, a radius of the first drum and the second drum, and a spacing being half the distance between the first drum and the second drum.
10. The winding machine according to claim 8 , wherein the accent rate is determined by the following expression (1):
AR
=
d
*
v
2
*
π
*
R
*
(
1
+
R
+
r
(
r
+
R
)
2
-
(
r
+
s
)
2
)
,
(
1
)
where d is a thickness of the sheet material,
v is a velocity of the sheet material with which the sheet material is fed to the finishing roll,
r is the radius of the first drum and the second drum, and
R is the radius of the finishing roll, and
s is a spacing being half the distance between the first drum and the second drum.
11. A method for controlling a second nip pressure applied by a rider roll onto a finishing roll during winding of a sheet material on the finishing roll, comprising:
supporting the finishing roll by a support drum assembly arranged on a first side of the finishing roll and configured to support the finishing roll from the first side; and
adaptively controlling, via an adaptive control unit, the second nip pressure applied by a rider roll onto the finishing roll, wherein the rider roll is arranged on a second side of the finishing roll opposite to the first side,
wherein the second nip pressure is adaptively controlled depending on an ascent rate of the rider roll, which is proportionate to a derivative of a radius of the finishing roll.
12. The method according to claim 11 , wherein the ascent rate of the rider roll is a function of growth rate of the finishing roll relative to the support drum assembly due to the sheet material being wound on the finishing roll.
13. The method according to claim 11 , wherein the ascent rate of the rider roll is calculated based on the radius of the finishing roll, a velocity of the sheet material with which the sheet material is fed to the finishing roll, a thickness of the sheet material and a geometry of the winding machine.
14. The method according to claim 11 , further comprising:
controlling the second nip pressure applied from the second side to generate a constant or slightly decreasing first nip pressure between the finishing roll and the support drum assembly.
15. The method according to claim 11 , further comprising:
feeding the sheet material to the finishing roll by the support drum assembly.