WO2003040472A1

WO2003040472A1 - Arrangement for closing and opening a roll nip in a shoe calender

Info

Publication number: WO2003040472A1
Application number: PCT/FI2002/000860
Authority: WO
Inventors: Kari Hasanen
Original assignee: Metso Paper, Inc.
Priority date: 2001-11-06
Filing date: 2002-11-05
Publication date: 2003-05-15
Also published as: FI5264U1; FIU20010418U0

Abstract

The invention relates, for example, to an arrangement for closing and opening a roll nip in a shoe calender (1), whereby the shoe calender has a shoe roll (4) provided with at least one shoe (2), a backing roll (5) being opposite to the shoe roll, and the roll nip (N) is left between the shoe roll and the backing roll, in which roll nip it is possible to calender a fibrous web (W). An axle journal (5) is attached to the end of the body (4; 41) of the shoe roll, a torque roll (9) being attached to the axle journal. The axle journal (5) is attached to the body (4; 41) of the shoe roll so that the longitudinal axis (P2) of the axle journal and the longitudinal axis (P1) of the shoe roll are on different levels.

Description

Arrangement for closing and opening a roll nip in a shoe calender

The invention relates, for example, to an arrangement according to claim 1 for closing and opening a roll nip in a shoe calender. In the shoe calender, there is a shoe roll, opposite to which there is a heated thermo roll. The thermo roll and the shoe roll are attached to an enclosed body at their bearing housings. Between the jackets of the shoe and the thermo rolls, there is a roll nip, wherein it is possible to calender a fibrous web, such as a paper or board track. One of the most commonly used shoe rolls consists of a stationary roller body, around which an endless belt, i.e., the jacket of the shoe roll rotates. The jacket of the shoe roll is attached to rotatable end flanges of the roller body. In the shoe roll, next to the roll nip, there is a shoe, the curvature of its shoe element corresponding to the curvature of the backing roll, whereby the length of the roll nip in the machine direction increases compared with the roll nip between two ordinary rolls. The shoe of the shoe roll can be pressurized by means of a loading element that is under the shoe element, which loading element in one type of a shoe roll consists of two rows of hydraulic cylinders under the shoe, which are supported on a sheet body below the cylinders.

When the calendering of the fibrous track is stopped, the roll nip must be opened to prevent overheating the jacket surrounding the roller body of the shoe roll. To arrange an air slot in the roll nip, the shoe roll is lowered by means of the hydraulic cylinders connected to the bearing housings located at the ends of the shoe roll, and when restarting calendering, the jacket of the shoe roll is lifted from its bearing housing into a close contact with the bearing housing of the backing roll (the thermo roll), whereby the roll nip is closed.

One drawback in opening and closing the roll nip between the shoe roll and the thermo roll implemented in this way is that lifting and lowering the entire shoe roll from the bearing housings requires a considerable amount of energy and thus in- creaces the calendering costs. Another drawback is the great investment cost caused by the enclosed stationary body.

The purpose of the invention is to eliminate the drawbacks of the prior art. Consequently, the main object of the invention is to provide a method for opening and closing the roll nip between the shoe roll and the thermo roll, whereby it would not be necessary to lift and lower the entire shoe roll. Another purpose of the invention is to decrease the investment cost caused by the present enclosed body by making the present structure of the roll mounting arrangement lighter. The above objects are accomplished by the arrangement according to the invention. To be more precise, the invention relates to the arrangement according to Claim 1.

The basic idea of the invention is to give up the enclosed body and to attach the bearing housings of the thermo and the shoe rolls to each other by means of fasten- ing members, such as long bolts. Torque rods are fixed to the axle journals at the ends of the shoe roll. The axle journals are located eccentrically with respect to the roller body. By turning the axle journal by means of the torque rod, the body of the shoe roll, which is eccentrically attached to the axle journal, and the shoe of the shoe roll that is supported on the body are turned at the same time. Because of the eccentric fastening between the torque rod and the body, the body and the shoe of the shoe roll move along the movements of the torque rod and away from the thermo roll and then back towards the thermo roll. The jacket of the shoe roll surrounds the body of the shoe roll, following the movements of the body, whereby the air slot between the shoe roll and the thermo roll can be opened and closed. In the arrangement according to the invention for closing and opening the roll nip, the shoe calender has a shoe roll provided with at least one shoe, a backing roll being provided against the shoe roll, and a roll nip being formed between the shoe roll and the backing roll, wherein it is possible to calender the fibrous track. An axle journal is attached to the end of the body of the shoe roll, a torque rod being at- tached to the axle journal. In the invention, the axle journal is attached to the body of the shoe roll so that the longitudinal axis of the axle journal and that of the shoe roll are on different levels, and it is possible to turn the body of the shoe roll around its longitudinal axis by means of the torque rod attached to the axle journal. The bearing housing of the shoe roll and the bearing housing of the backing roll are at- tached to each other by means of elongated fastening members.

In a preferred embodiment of the invention, the longitudinal axis of the axle journal and that of the shoe roll are located with respect to each other so that the distance of the straight line running through the longitudinal axis of the axle journal from the jacket of the shoe roll is shorter than the distance of the straight line running through the longitudinal axis of the shoe roll from the jacket of the shoe roll.

In another preferred embodiment of the invention, the shoe roll has two shoes, the width of their shoe elements in the machine direction being different.

The fastening arrangement of the thermo roll and the shoe roll according to the invention has a structure that is considerably lighter and thus incurs less investment costs than the enclosed body used before. To open and close the roll nip in the invention, it is not necessary to lift the entire shoe roll with its bearing housings, but it is sufficient to turn the body of the shoe roll by means of the axle journal and the torque rod attached thereto so that the shoe of the shoe roll moves away from the roll nip and back to the roll nip. At the same time, the jacket of the shoe roll moves away from the backing roll and then back into contact with the backing roll, whereby the roll nip opens and closes.

Regarding any further advantages provided by the invention, it should be mentioned that in the method according to the invention, the shoe width of the shoe roll (in the machine direction) can be adjusted, if there are two shoes in the shoe roll at opposite sides of the body, the width of the shoe elements of the shoes in the machine direction being different. In that case, the body can be turned by means of the torque rod so that the shoe of the shoe roll of a desired width comes to the roll nip. In that case, the shoe is preferably a convex or straight sheet that is hydrodynamically lubricated, and the angle between the edges of the shoe and the fibrous track is about 45 degrees. The fastening arrangement between the thermo roll and the shoe roll used in the invention also enables an easier replacement of the belt of the shoe roll than before; when the shoe and the thermo rolls are no longer located in a stationary enclosed body but are attached to each other at their bearing housings only, the shoe roll can be detached by supporting the thermo roll against a pole and by moving the shoe roll aside and up, after which the belt of the shoe roll can be replaced. In the following, the invention is described in detail with reference to the appended drawings.

Figs. 1A and IB show schematically a shoe calender as viewed directly to the end of the pair of rolls formed by a shoe roll and a thermo roll.

Figs. 2 A and 2B show schematically a longitudinal section of one end of the shoe roll with its axle journals.

In the following, we will first briefly describe the aspects of the invention we intend to illustrate in the respective figures and, after that, the structures shown in tl e figures.

Figs. 1A and IB illustrate the shoe calender 1 according to the invention, and the opening and closing of the roll nip N of the shoe calender by means of a torque rod 9 mounted on bearings to an axle journal 5. Figs. 1A and IB show the shoe calender 1 as viewed directly towards the end of the calender. Fig. 1A shows the roll nip N between a thermo roll 6 and a shoe roll 4 in a opened position and Fig. IB shows the same roll nip N in a closed position. The shoe calender 1 shown in Figs. 1A and IB is provided with the thermo roll 6 and the shoe roll 4 that is opposite to the thermo roll. The roll nip N is formed be- tween the thermo roll and the shoe roll, the fibrous track W that is to be calendered travelling in the nip. The bearing housing 7 of the thermo roll and the bearing housing 8 of the shoe roll are interconnected by means of two long bolts 3; there is no separate enclosed body in the calender. Around the body 4; 1 of the shoe roll of the shoe calender, there is an endless belt, i.e., the jacket 4; 42 of the shoe roll. The torque rod 9 is mounted on bearings to the axle journal 5 of the shoe roll, being used to compensate for any stresses exerted on the ends of the shoe roll 4 during calendering. A lubricating oil channel 12 leads inside the axle journal.

Figs 2 A and 2B illustrate in detail the structure and the location of the axle journal 5 of the shoe roll 4 and the body 4; 41 of the shoe roll, and those of the shoe 2 of the shoe roll with respect to one another, when the axle journal 5 and the body 4; 41 of the shoe roll are located in different positions with respect to one another. In Fig. 2A, the axle journal 5 is in its upper position, whereby the body 4; 41 is in its lower position. The shoe 2 of the shoe roll has turned away from the roll nip. In Fig. 2B, the axle journal 5 is turned to its lower position by means of the torque rod 9, whereby the body 4; 41 of the shoe roll, in turn, is turned to its upper position and, at the same time, the shoe 2 of the shoe roll is turned next to the roll nip.

Figs. 2A and 2B show part of the body 4; 41 of the shoe roll. A short body pin 4; 44 is attached to the end of the body 4; 41 in a coaxial relationship to the centre line PI of the body. The axis 5; 52 of the axle journal is eccentrically attached to the body pin 41 ; 44. The body 4; 41 of the shoe roll is attached to the body 5; 51 of the axle journal by means of bolts 11. The axis 5; 52 of the axle journal is located inside the axle journal 5 in a coaxial relationship to its centre line P2, which is why the centre line P2 of the axle journal 5 (the longitudinal axis of the axle journal) and the centre line PI of the body 4; 41 of the shoe roll (the longitudinal axis of the body) are located in an eccentric relationship to one another. An end flange 4; 43 of the shoe roll, to which the jacket 4; 42 of the shoe roll is attached, is rotatably supported on a portion of the axle journal body 5; 51 on the side of the shoe roller body, i.e., on the rear of the axle journal. The front of the axle journal body 5; 51 is rotatably attached to the bearing housing 8 of the shoe roll. The front of the axle journal body 5; 51 is also provided with a torque rod 9, by which the axle journal 5 can be pivoted around its longitudinal axis P2. When the axle journal is turned around its longitudinal axis P2, the body 4; 41 of the shoe roll turns simultaneously around its longitudinal axis PI. The longitudinal axis PI of the shoe roller body is located on the centre line of the shoe roll. A loading element 2; 21 of the shoe 2 is attached to the shoe roller body 4; 41, consisting of loading members. The loading members consist of two rows of hydraulic cylinders, which can be used to pressurize the shoe element 2; 22 of the shoe 2, which is supported on the upper surface of the loading members. For the sake of simplicity, Figs. 2 A and 2B do not show the hydraulic fluid and lubricant circulations used for pressurizing the hydraulic cylinders and for lubricating between the shoe of the shoe roll and the jacket of the shoe roll. In the shoe calender shown in Fig. 1A, the hydraulic delivery and return hoses of the lubricating oil channel 12 have turned on top of each other, i.e., the plane running through them is in a 90 degree angle to the plane of the fibrous web W. The axle journal 5 has been turned around its longitudinal axis by means of the torque rod 9. The longitudinal axis of the axle journal is above the longitudinal axis of the shoe roller body, i.e., in its upper position, and the body of the shoe calender and the shoe that is attached to the body (shown in detail in Figs. 2 A and 2B) have moved away from the roll nip N, simultaneously forcing the jacket 4; 42 of the shoe calender to withdraw from the jacket of the thermo roll, whereby the roll nip N is opened. In Fig. IB, the hydraulic delivery and return hoses 12 of the lubrication and pressurizing system of the shoe of the shoe roll are side by side, i.e., as a result of the shoe 2 of the shoe calender moving back next to the roll nip N, the plane running through the hoses runs in parallel with the plane of the fibrous track W. The axle journal 5 has been turned around its longitudinal axis by 180 degrees with respect to the situation in Fig. 1 A. The axle journal 5 is in its lower position, i.e., its longitudinal axis is below the longitudinal axis of the body, and the shoe of the shoe roll below the jacket 4; 2 of the shoe roll, and the body of the shoe roll (shown in detail in Figs. 2A and 2B) are in their upper positions. In that case, they have approached the jacket of the thermo roll 6, at the same time forcing the jacket 4; 2 of the shoe roll into contact with the fibrous web W, whereby the roll nip N is closed.

In Fig. 2A, the axle journal 5 has been turned around its longitudinal axis P2 by means of the torque rod 9 so that the longitudinal axis P2 of the axle journal is above the longitudinal axis PI of the shoe roller body. The axle journal 5 is in its upper position and the body 4; 41 of the shoe roll is in its lower position. The dis- tance K2 of the straight line S2 running through the centre line of the axle journal 5 and, at the same time, the longitudinal axis P2 of the axle journal, from the jacket 4; 42 of the shoe roll is shorter than tl e distance Kl of the straight line SI running through the centre line of the shoe roller body and, at the same time, the longitudinal axis PI of the shoe roll/shoe roller body, from the jacket 4; 42 of the shoe roll. The shoe 2 of the shoe roll has turned away from the roll nip N to its lower position, where it is located on the opposite side of the shoe roll as viewed from the roll nip. In Fig. 2B, the axle journal 5 has been turned around its longitudinal axis P2 by means of the torque rod so that the longitudinal axis PI of the shoe roller body 4; 41 has moved above the longitudinal axis of the axle journal. The body 4; 41 of the shoe calender and the shoe 2 of the shoe roll that is supported on it have turned to their upper positions, i.e., next to the roll nip N. The distance of the straight line S2 running through the centre line of the axle journal 5 and, at the same time, the longitudinal axis P2 of the axle journal, from the jacket of the shoe roll is K2, which is shorter than the distance Kl of the straight line SI running through the centre line of the shoe roller body and, at the same time, the longitudinal axis PI of the shoe roll/shoe roller body, from the jacket 4; 42 of the shoe roll.

When the axle journal 5 is turned around its longitudinal axis by means of the torque rod 9, the longitudinal axis P2 of the axle journal is thus ever closer to the jacket 4; 42 of the shoe roll than the longitudinal axis PI of the shoe roller body 4; 41. During the transfer, the shoe 2 of the shoe roll remains in contact with the jacket 4; 42 of the shoe roll. At the same time, a rotation of the body and the shoe away from the backing roll (the thermo roll) and towards the backing roll forces the jacket 4; 42 of the shoe roll to move away from the nip contact and into a nip contact with the jacket of the backing roll. During calendering, a bed of lubricant, which is not shown in the figure, is formed between the shoe 2 of the shoe roll and the jacket 4; 42 of the shoe roll.

Only one embodiment of the calendering arrangement according to the invention is disclosed above, and it is obvious to those skilled in the art that the invention can also be implemented in various other ways within the inventive idea described in the claims. Consequently, the calendering arrangement according to the invention can also be used to implement any changes in the shoe width of the calender roll: if a first shoe is attached to one side of the body of the shoe calender, the shoe element of which has a first width in the machine direction, and a second shoe is attached to the opposite side of the body, the shoe element of which has a second width in the machine direction, any changes in the shoe width are easy to make by turning the axle journal by means of the torque rod so that the shoes change places. In such a calender roll, the lubrication between the shoe of the shoe roll and the jacket of the shoe roll is preferably hydrodynamic; in other words, the lubricant runs from one side of the shoe to the other in the machine direction. The arrangement according to the invention can also be implemented so that in the bearing housing of the shoe roll of the shoe calender, there is a piece around the axle journal 5, the longitudinal axis of which is in an eccentric relationship to the longitudinal axis of the axle journal, and the torque rod 9 is attached to this eccentric piece. The longitudinal axis of the axle journal in this embodiment is on the same plane as the longitudinal axis of the shoe roll, whereby the longitudinal axis of the eccentric piece is on a different plane to both the longitudinal axis of the axle journal and that of the shoe roll.

Claims

1. An arrangement for closing and opening a roll nip in a shoe calender (1), whereby the shoe calender has a shoe roll (4) provided with at least one shoe (2), a backing roll (5) being opposite to the shoe roll, and the roll nip (N) is left between the shoe roll and the backing roll, in which roll nip it is possible to calender a fibrous web (W), and an axle journal (5) is attached to the end of the body (4; 41) of the shoe roll, a torque rod (9) being attached to the axle journal, characterized in that - the axle journal (5) is attached to the body (4; 41) of the shoe roll so that the longitudinal axis (P2) of the axle journal and the longitudinal axis (PI) of the shoe roll are on different levels.

2. An arrangement according to claim 1, characterized in that the body (4; 41) of the shoe roll can be turned around its longitudinal axis (PI) by means of the torque rod (9) attached to the axle journal (5).

3. An arrangement according to any of the previous claims, characterized in that the longitudinal axis (P2) of the axle journal and the longitudinal axis (PI) of the shoe roll are located with respect to one another so that the distance (K2) of the straight line (S2) running through the longitudinal axis of the axle journal from the jacket (4; 42) of the shoe roll is shorter than the distance (Kl) of the straight line (SI) running through the longitudinal axis of the shoe roll from the jacket (4; 42) of the shoe roll.

4. An arrangement according to any of claims 1 to 3, characterized in that in the shoe roll (4), there are two shoes (2), the width of the shoe elements (2; 22) of the shoes in the machine direction being different.

5. An arrangement according to any of the preceding claims, characterized in that the bearing housing (8) of the shoe roll (4) and the bearing housing (7) of the backing roll (6) are attached to each other by means of elongated fastening members (3).