Press device with an extended nip, a paper making machine and a method of operating a press device

1. A press device ( 1 ) comprising:

an extended nip roll ( 2 ); and

a counter roll ( 3 ),

wherein:

the extended nip roll ( 2 ) comprises a flexible jacket ( 4 ) and a support body ( 5 ) inside the flexible jacket ( 4 );

the extended nip roll ( 2 ) comprises internal means for causing the support body ( 5 ) to move or expand radially towards an inner surface ( 6 ) of the flexible jacket ( 4 ) to form a nip with the counter roll ( 3 );

the counter roll ( 3 ) comprises axial ends ( 7 , 8 ) supported in first bearing housings ( 9 );

the extended nip roll ( 2 ) comprises axial ends ( 10 , 11 ) supported in second bearing housings ( 12 );

at least one actuator ( 13 ) connects the first bearing housings ( 9 ) to the second bearing housings ( 12 ) and the at least one actuator ( 13 ) is configured to be capable of acting on the bearing housings ( 9 , 12 ) to cause the bearing housings ( 12 ) of at least one of the rolls ( 2 ) to move at least one of towards the bearing housings ( 13 ) of the other roll ( 3 ) in a closing movement or away from the bearing housings of the other roll ( 3 ) in an opening movement; and

a mechanical stop ( 14 ) separate from the rolls ( 2 , 3 ) is configured to halt the closing movement when the closing movement has brought the rolls ( 2 , 3 ) so close to each other that the axial ends ( 10 , 11 ) of the extended nip roll ( 2 ) and the axial ends ( 7 , 8 ) of the counter roll ( 3 ) are at a predetermined distance from each other.

2. A press device according to claim 1 , wherein the mechanical stop is formed by at least a part of the bearing housing ( 9 , 12 ) for each axial end ( 7 , 8 , 10 , 11 ) of a roll ( 2 , 3 ).

3. A press device according to claim 1 , wherein the actuator ( 13 ) is a hydraulic cylinder with a piston.

4. A press device according to claim 3 , wherein the mechanical stop ( 14 ) is configured to halt the piston before the piston has reached a completely retracted position.

5. A press device according to claim 1 , wherein the mechanical stop ( 14 ) comprises at least one load sensor that is arranged between one of the first bearing housings ( 9 ) and one of the second bearing housings ( 12 ).

6. A press device according to claim 1 , wherein the support body ( 5 ) either comprises or is supported by a flexible hose extending in a cross machine direction and connected to a source of pressurized fluid ( 16 ) such that pressurization of the flexible hose will cause the support body ( 5 ) to expand or move radially in a direction towards the inner surface ( 6 ) of the flexible jacket ( 4 ).

7. A press device according to claim 1 , wherein an actuator ( 13 ) is connected to each bearing housing ( 9 , 12 ) of a roll ( 2 , 3 ).

8. A press device according to claim 1 , wherein:

the rolls ( 2 , 3 ) have axes (A, B) that define a press plane; and

the at least one actuator ( 13 ) is configured to act on one side of the press plane while the bearing housings ( 9 , 12 ) are hingedly connected to each other on the other side of the press plane.

9. A press device according to claim 8 , wherein, at each roll end, the at least one actuator ( 13 ) is connected to the respective second bearing housing ( 12 ) through a connection beam ( 49 ) that is hingedly connected to the first bearing housing ( 9 ) at a first end ( 20 ) of the connection beam ( 49 ) and hingedly connected to the at least actuator ( 13 ) at a second end ( 21 ) of the connection beam ( 49 ).

10. A press device according to claim 9 , wherein, at each roll end, the at least one actuator ( 13 ) is hingedly connected to the first bearing housing ( 9 ) and to the second end ( 21 ) of the connection beam ( 49 ).

11. A press device according to claim 9 , wherein, at each roll end, the connection beam ( 49 ) is detachably connected to the second bearing housing ( 12 ).

12. A press device according to claim 1 , wherein the extended nip roll ( 2 ) is a lower roll and the counter roll ( 3 ) is an upper roll.

13. A press device according to claim 1 , wherein the counter roll is a heatable roll ( 3 ).

14. A paper making machine having a head box ( 33 ) and a press device ( 1 ), wherein the press device being designed according to claim 8 and the at least one actuator ( 13 ) is located upstream of the press plane.

15. The paper making machine of claim 14 , wherein the at least one actuator is located between the head box and the press plane.

16. A method of operating a press device according to claim 1 , wherein the method comprises the steps of using the at least one actuator ( 13 ) that connects the bearing housings ( 9 , 12 ) to perform a closing movement until the closing movement is halted by the mechanical stop ( 14 ); and finally cause the support body ( 5 ) to be pressed against the inner surface ( 6 ) of the flexible jacket ( 4 ) such that the flexible jacket ( 4 ) moves towards the counter roll ( 3 ) to exert pressure in the nip (N).