ROLL SLEEVE

Abstract

A roll sleeve for use in a press device for the dewatering of paper, cardboard, tissue or another fibrous web in a papermaking machine for the production and/or conversion of the web. The roll sleeve including an outer sleeve having a surface. The surface including a plurality of grooves progressing approximately in a circumferential direction. The grooves being axially adjacent and arranged in the same direction. The grooves having a length, The grooves being offset against each other by a substantially equal amount. The amount of the offset being between 10% and 50% of the groove length.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a roll sleeve for a press device for the dewatering of a paper, cardboard, tissue or other fibrous web in a machine for the production and/or conversion of the web.

2. Description of the Related Art

Roll sleeves known from DE 197 52 725 allow for a gentle, yet intensive dewatering. On entry of a groove on the outer sleeve surface in the press nip, the pressure builds up only slowly due to the connection to the atmospheric pressure of the environment. If the groove exceeds the press nip end, a drop in pressure occurs, resulting in water spraying out of the groove. This increases its water receptivity when re-entering the press nip and thereby also increases the dewatering capacity.

However the bridges remaining in the circumferential direction between the grooves which, due to irregular hydraulic pressure, can lead to considerable marking of the fibrous web which is detrimental.

Furthermore, the production of these grooves is very expensive.

What is needed in the art is an apparatus to reduce the production costs for these grooves as well as to limit possible marking of the web.

SUMMARY OF THE INVENTION

In the present invention the outer sleeve surface includes grooves progressing in approximately circumferential direction, whereby axially adjacent grooves are arranged in the same direction and are offset against each other by the same amount and the amount of the offset is between 10 and 50% of the groove length. This creates not only a uniform groove positioning, but when milling the grooves, relatively numerous grooves starting on one axial sleeve line can be milled simultaneously in one work process,.

Here it is advantageous if the amount of the offset is 20% or 25% or 33%. Accordingly, every third to fifth groove begins on the same axial sleeve line. In the interest of a large open roll sleeve surface the distance between adjacent grooves in the circumferential direction should be between 5 and 15 mm. In the same context the axial distance between adjacent grooves should be between 2 and 4 mm.

In order to ensure great water receptivity, the grooves should be between 0.4 and 2 mm wide and between 0.5 and 2 mm deep, preferably between 1 and 1.5 mm deep. The axial side walls of the grooves can progress vertically or slightly slanting. They may also be chamfered.

In order to hereby minimize the danger of tears at the transition between the side walls and the groove bottom, the groove bottom is formed in an axial direction by the arc of a circle whose radius is between 0.2 mm and 1 mm, preferably between 0.5 and 0.8 mm.

In order to avoid marking on the fibrous web, caused by abrupt transitions at the groove ends, the groove bottom at the groove ends should be formed in a circumferential direction by the arc of a circle whose radius is between 30 and 150 mm, preferably between 60 and 100 mm.

Here it has proven to be advantageous if the grooves, in the circumferential direction, have a length of between 50 and 150 mm. In addition, a return flow in the direction of the press nip inlet of the water, which was collected by the groove, is impeded if the grooves have a length in the circumferential direction, which corresponds to between 20 and 60% of the length of the press nip, which is formed by the roll sleeve and a mating roll.

In order to increase the open area of the roll sleeve and thereby of the water retention volume it can be advantageous if the roll shell is equipped with blind bores which can be located between the grooves and/or in the grooves.

In addition it can be advantageous to combine the large water receptivity of recesses with the improved dewatering characteristic of the grooves in that the roll sleeve additionally include recesses extending over the entire roll circumference.

Depending upon the type of fibrous web which is to be dewatered and depending upon the amount of water to be removed it is advantageous if the recesses are located axially between the grooves and/or if at least one recess zone with several axially adjacent recesses.

In order to ensure sufficient flexibility, stability and load capacity of the roll sleeve, the roll sleeve is made of a flexible material and should preferably contain woven, fibrous or thread-type reinforcement material.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a schematic cross section view through a shoe press in a papermaking machine;

FIG. 2 is a partial top view of an embodiment of a roll sleeve of the present invention;

FIG. 3A illustrates a cross sectional view through a groove of the roll sleeve of FIG. 2; and

FIG. 3B illustrates a longitudinal cross sectional view through the groove of the roll sleeve of FIG. 2.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, and more particularly to the press arrangement illustrated in FIG. 1, there is shown a fibrous web 1 together with a water absorbing and a water permeable dewatering belt 11 and 12 on each side of fibrous web 1 in the form of a press felt is carried through the press nip, which is formed by a shoe press roll 3 and a mating roll 6. The water, which is pressed from fibrous web 1, is absorbed by dewatering belts 11 and 12 and is partially transferred to roll sleeves 2. In order to increase the water receptivity at least roll sleeve 2 of shoe press 3 is contoured.

In the interest of a gentle, but intensive dewatering of fibrous web 1, the press nip is extended. Therefore, shoe press roll 3 possesses a flexible roll sleeve 2, constructed of a fiber reinforced synthetic material which is pressed by a pressure element 10 having a concave press surface onto a cylindrical mating roll 6.

The contour of roll sleeve 2 is essentially provided by grooves 4 which progress in a circumferential direction 9 and which also may be supplemented by blind bores and/or continuous recesses progressing in circumferential direction 9.

In order to ensure an as uniform as possible dewatering, the axially adjacent grooves 4 as viewed in an axial direction are located offset to each other by 33% of the groove length in the same direction, as shown in FIG. 2 in circumferential direction 9. Therefore, every third axially adjacent groove 4 starts on the same axial sleeve line so that several of these grooves 4 can be milled simultaneously, using one milling cutter.

While the distance between adjacent grooves 4 in circumferential direction 9 is between 5 and 15 mm, the axial distance between adjacent grooves is between 2 and 4 mm.

In order to create a large water retention capacity grooves 4 have a width of between 0.4 and 2 mm and a depth of between 1 and 1.5 mm.

Side walls 5 of grooves 4 are essentially vertical and transition into a groove bottom 7 which, in order to minimize tensions in roll sleeve 2, according to FIG. 3A, as viewed in the axial direction is formed by the arc of a circle whose radius is between 0.5 and 0.8 mm.

In order to create an as gradual as possible transition between grooves 4 and groove bridges, groove bottom 7 at groove ends 8, as viewed in circumferential direction 9 as shown if FIG. 3B, is formed by an arc of a circle whose radius is between 60 and 100 mm. This supports an as uniform as possible dewatering characteristic and allows for short groove bridges between grooves 4 in circumferential direction 9.

To prevent the water in grooves 4 in the press nip from flowing back in the direction of the press nip inlet, grooves 4 have a length in circumferential direction 9 which is consistent with between 20 and 60% of the length of the press nip, in this instance specifically between 50 and 150 mm.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1. A roll sleeve for use in a press device for the dewatering of at least one of a paper, cardboard, tissue and other fibrous web in a papermaking machine for the production and/or conversion of the web, the roll sleeve comprising: an outer sleeve having a surface including a plurality of grooves progressing approximately in a circumferential direction, said grooves being axially adjacent and arranged in a corresponding direction, said grooves having a length, said grooves being offset against each other by a substantially equal amount, said amount of said offset being between 10% and 50% of said groove length.

2. The roll sleeve of claim 1, wherein said amount of said offset is 20%.

3. The roll sleeve of claim 1, wherein said amount of said offset is 25%.

4. The roll sleeve of claim 1, wherein said amount of said offset is approximately 33%.

5. The roll sleeve of claim 1, wherein said grooves have a distance between adjacent grooves in a circumferential direction, said distance being between 5 mm and 15 mm.

6. The roll sleeve of claim 5, wherein said grooves have a width, said width being between 0.4 mm and 2 mm.

7. The roll sleeve of claim 6, wherein said grooves have an axial distance between adjacent grooves, said axial distance being between 2 mm and 4 mm.

8. The roll sleeve of claim 7, wherein said grooves have a depth, said depth being between 0.5 mm and 2 mm.

9. The roll sleeve of claim 8, wherein said depth is between 1 mm and 1.5 mm.

10. The roll sleeve of claim 9, wherein said grooves have a bottom formed in the axial direction by an arc of a circle, said arc having a radius of between 0.2 mm and 1 mm.

11. The roll sleeve of claim 10, wherein said radius is between 0.5 mm and 0.8 mm.

12. The roll sleeve of claim 10, wherein said bottom of said grooves have two ends, said groove ends being formed in the circumferential direction by an arc of a circle whose radius is between 30 and 150 mm.

13. The roll sleeve of claim 12, wherein said groove ends are formed in the circumferential direction by an arc of a circle whose radius is between 60 mm and 100 mm.

14. The roll sleeve of claim 12, wherein said length of said grooves is between 50 mm and 150 mm in the circumferential direction.

15. The roll sleeve of claim 12, wherein said grooves have a length, said length being in the circumferential direction, said length corresponding to between 20% and 60% of a length of a press nip which is formed by said roll sleeve and a mating roll.

16. The roll sleeve of claim 15, wherein the roll sleeve is equipped with blind bores.

17. The roll sleeve of claim 16, wherein said blind bores are located between said grooves.

18. The roll sleeve of claim 16, wherein said blind bores are located in said grooves.

19. The roll sleeve of claim 1, wherein said outer sleeve surface includes a plurality of recesses extending over the entire roll circumference.

20. The roll sleeve of claim 19, wherein said recesses are located axially between said grooves.

21. The roll sleeve of claim 19, wherein said outer sleeve surface includes at least one recess zone having a plurality of axially adjacent recesses.

22. The roll sleeve of claim 21, wherein said at least one recess zone is positioned at an end of the roll.

23. The roll sleeve of claim 1, wherein said roll sleeve consists of a flexible material.

24. The roll sleeve of claim 23, wherein said flexible material includes at least one of a woven material, a fibrous material and a thread-type reinforcement material.