DE102012200461A1 - Roller cover for roller in web manufacturing or processing machine, has circumferential grooves and multiple holes formed as blind holes or suction holes, where cross section of circumferential grooves and blind holes has continuous profile - Google Patents

Abstract

The roller cover (2) has one or multiple circumferential grooves (6) and multiple holes formed as blind holes (4a) or suction holes (4b). Cross section of the circumferential grooves and blind holes has a continuous profile. A wall (8) of the blind holes and circumferential groove passes in an area (9) of the blind holes or the circumferential groove without edges. Shape of the cross section is substantially conical with a rounded end or cylindrical with a hemispherical end.

Description

The invention relates to a roll cover for a roll for use in a web-forming, web-processing or web-finishing machine such as a paper, board or tissue machine according to the preamble of claim 1.

Such rolls are known in a variety of positions in fibrous web machines and usually have on a roll core, which may for example consist of metal or a fiber composite material, a roll cover as a functional layer. This is in some positions directly, in other positions indirectly via a papermachine fabric with the fibrous web in contact. The roll cover fulfills various tasks, for example the dewatering of the fibrous web, the drying or smoothing of the same.

Depending on the position, the roll cover can be formed of various materials, preferably of polyurethane or rubber mixtures, furthermore thermal coatings with metals and ceramics as well as fiber composite materials as a functional layer are known.

In the case of polyurethane and rubber covers, which are used in the majority in the wet end of paper, board or tissue machines, according to the current state of the art in a Arbeitskontaktfläche the roll cover many surface forms are attached, which serve better drainage of the fibrous web. The surface shapes are mostly in the form of holes and grooves. The holes may be in evacuated positions in the form of through or suction holes. Blind holes or blind holes may be provided in suctioned rolls in addition to increasing the dewatering capacity, or may be present in unsatisfied positions alone. The holes can be combined with grooves made as spiral grooves or as single cuts. Even grooves alone are known.

From the EP1103654 For example, a roll having a hollow shell with perforations and a roll cover is known wherein the roll cover is provided on the perforated hollow shell and includes an outwardly facing work contacting surface in which a plurality of through bores are provided extending through the roll cover and aligned with respective shell perforations are to provide suction holes in the roller. The work contact surface further includes a plurality of drilled blind holes, wherein the cross-sectional area of each through hole corresponds to the each drilled blind hole. The working contact surface also includes a continuous circumferential groove connecting the through-holes.

A disadvantage of the surface forms used hitherto and known from the prior art is, in particular, that on the one hand, due to their mere presence and, on the other hand, due to their shape and manufacturing process, they can weaken the roll cover with the consequence of cracking, so that fractures occur under continuous load during operation the roll cover with at least partial detachment of the same can occur from the roll core, which can subsequently cause severe damage to the fiber web machine and also hold a high risk potential for the operator by uncontrolled flying away reference parts.

It is accordingly an object of the invention to provide a roll cover in which the risk of cracking is reduced by the introduced surface shapes and which thus on the one hand allows safer use and at the same time ensures good drainage of the fibrous web.

The object is achieved by the characterizing features of claim 1 in conjunction with the generic features.

According to the invention, it is provided that a cross-section of the surface shapes such as blind holes or circumferential grooves has a substantially continuous course, in which a wall of the respective surface shape merges edge-free in a base surface of the respective surface shape.

Further advantageous embodiments and modifications of the invention are specified in the subclaims.

Advantageously, the shape of the cross section may be substantially conical. According to a further advantageous embodiment variant, the shape of the cross section may be substantially cylindrical with a semicircular termination.

Both forms have in common that they have a constant application of force through the walls in the base areas and thus reduce the formation of cracks in deformation of the roll cover during operation of the machine. The service life and reliability are thus increased.

Another advantage of the forms described is the improved release of water from the surface forms, since the capillary forces and the surface tension of the water when rounded Cross sections come less to fruition than in the usual according to the prior art polygonal cross-sectional shapes.

The invention will be explained in more detail with reference to the drawings. Showing:

1 a roll cover according to the prior art, and

2 a highly schematic embodiment of an inventively designed roller cover.

In 1 is for better understanding of the inventive measures, first a section of a known roll cover 2 a roller 1 for use in a web forming, refining or processing machine such as a paper, board or tissue machine according to the prior art.

The roll cover 2 consists of an elastomer such as polyurethane or rubber. On a detailed description of materials, thickness, base and the like can be omitted here, since the construction of elastic roll covers for paper machines has long been known.

The roll cover 2 is on a roll core 3 arranged and preferably firmly connected thereto. In roll cover 2 are holes 4 formed, which as blind holes 4a and suction holes 4b are executed. The latter are on through holes 5 in the roll core 3 aligned and serve the extraction of water from the fibrous web, for example by means of a suction box, not shown in the interior of the roller 1 ,

Furthermore, at least one circumferential groove 6 in roll cover 2 provided, which is formed spirally and at least with a part of the holes 4 communicates.

How out 1 apparent, are both the blind holes 4a as well as the at least one circumferential groove 6 formed with a cross-section which is substantially cylindrically shaped. It is thus in the circumferential groove 6 as well as in the blind holes 4a edge 7 present, which has a sharp transition between walls 8th and footprint 9 form the respective surface shape at an angle of about 90 °.

These edges 7 are potential starting points for stress cracks that develop under load due to deformation of the roll cover 2 during operation of a paper machine train and large-scale detachment of the roll cover 2 being able to lead.

To counter this, the cross-sectional shape of the blind bores is provided according to the invention 4a and / or the at least one circumferential groove 6 so modify that the sharp edges 7 be avoided and the surface shapes obtained a cross-sectional shape, which provides no point of attack for cracking more and thus the stability and reliability of the roll cover 2 guaranteed. Detachment of the roll cover 2 can be prevented or at least delayed.

How out 2 apparent, are the blind holes 4a and the at least one circumferential groove 6 provided with a cross-section which is shaped substantially conically with a rounded end. This is the transition from the wall 8th to the base area 9 the mathematical speaking continuous surface form and has no abrupt changes in gradients or discontinuities.

It is also possible to have the cylindrically shaped cross sections with one in the case of blind bores 4a hemispherical or in the case of the circumferential groove 6 semicircular rounded conclusion to provide.

The cross-sectional shapes described here have not only the advantage of reliability and service life of the roll cover 2 but also to provide improved drainage performance. The reason for this is that the capillary action of the surface shapes and the adhesion of the water due to its surface tension is less pronounced in continuous surface shapes and thus the discharge of water from the surface shapes is facilitated.

The introduction of such shaped surface forums is possible with simple means, for example with so-called. Step drills.

The invention is not limited to the illustrated embodiments. In particular, it is possible to combine the different aspects with each other.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1103654 [0005]

Claims (3)

Roll cover ( 2 ) for a roller ( 1 ) for use in a web-making, processing or finishing machine, such as a paper, board or tissue machine, comprising at least one circumferential groove ( 6 ) and / or a plurality of holes ( 4 ), which are used as blind holes ( 4a ) or as suction holes ( 4b ) are formed, characterized in that a cross section of the at least one circumferential groove ( 6 ) and / or the plurality of blind bores ( 4a ) has a substantially continuous course, in which a wall ( 8th ) of the blind holes ( 4a ) and / or the at least one circumferential groove ( 6 ) free of edges into a base area ( 9 ) of the blind holes ( 4a ) and / or the at least one circumferential groove ( 6 ) passes over. Roll cover according to claim 1, characterized in that the shape of the cross section is substantially conical with rounded end. Roll cover according to claim 1, characterized in that the shape of the cross section is substantially cylindrical with a semicircular termination.

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