WO2013136047A1

WO2013136047A1 - Improvements in or relating to de-watering rolls

Info

Publication number: WO2013136047A1
Application number: PCT/GB2013/050479
Authority: WO
Inventors: Anthony ASHTON
Original assignee: Richard Hough Limited
Priority date: 2012-03-16
Filing date: 2013-02-27
Publication date: 2013-09-19
Also published as: GB201204762D0; GB2500269A

Abstract

There is disclosed a de-watering roll having a shaft, a resilient sub-layer provided around the shaft, and a resilient outer cover provided around the sub-layer. The sub-layer has a hardness which is greater than the hardness of the outer cover. A circumferential groove is formed in the sub-layer, the groove being substantially filled by the outer cover.

Description

IMPROVEMENTS IN OR RELATING TO DE-WATERING ROLLS

The present invention relates to a de-watering roil, and more particularly relates to a de- watering roil suitable for use in the textile industry.

It is known in the textile industry to use squeeze roils for mechanical drying of wet textiles. Conventionally, rubber covered squeeze rolls are used for this purpose in textile handling machinery such as squeezers, de-watering machines, mangles, foulards, hydro-extractors and presses. However, rubber covered rolls can also be used in the steel, plastic and printing industries, and so it is envisaged that the present invention could be used in such

applications. It is also to be appreciated that rolls in accordance with the present invention could be used for de-watering purposes in the paper industry, where suction rolls and press rolls are used.

Conventional rubber covered rolls comprise a central metal shaft having a journal section located at each end. A resilient cover material is provided over the shaft, the resilient material typically having a radial thickness of between 10mm and 20mm. Whilst natural rubber can be used for the resilient covering, it is more conventional to use synthetic eiastomeric

substances such as nitrile.

In a typical de-watering machine such as a mangle, two squeeze roils are arranged to run against one another, and are urged towards one another so that wet textile material can be passed through the nip defined between the two rollers, the rollers serving to squeeze liquid out of the textile material.

Rubber covered squeeze rolls have been found to be particularly useful in squeezing water from textile materials because the resilient material provided around the central shaft of the roll deforms slightly under the squeezing pressure applied to the roil, thereby increasing the area of the roll in contact with the textile material as it passes through the nip between the two rolls.

Prior art rubber covered squeeze roils of the type described above typically use resilient material having a hardness of approximately 95 Shore A. Resilient material of this level of hardness has been found to provide a reasonable balance between allowing sufficient defamation in order to increase the surface area of the roll in contact with textile material at the nip, whilst also retaining sufficient rigidity to provide an effecting squeezing action. However, prior art rubber covered squeeze rolls of the type described above are not without problems and although they have been found to provide reasonable results when used in textile de-watering machines, significant nip-pressure is still required in order to provide acceptable squeezing performance. More recently it has therefore been proposed to provide squeeze roils which have a plurality of resilient layers instead of just a single layer.

Typical multi-layer squeeze roils generally comprise a resilient sub-layer which is provided over and around the shaft of the roil, and a resilient outer cover which is provided around the sub-layer. The sub-layer is generally formed from a relatively hard rubber, and the outer cover is generally a relatively soft rubber which is bonded to the relatively hard sub-layer. The bond line between the two layers of rubber is normally protected by an end shroud of hard rubber which is bonded to the end surface of the roll so as to lie perpendicular to the axis of the roil, and which abuts the end edges of the sub-layer and outer cover at each end of the roil. The end shroud thus covers the edge of the bond formed between the two resilient layers, thereby protecting it from the ingress of water or moisture which could damage the integrity of the bond.

However, the use of end shrouds of the general type mentioned above is not without problems. For example, the join between the end shroud and the end edges of the sub-layer and the outer cover is generally a simple butt joint rather than a chemical bond, which is less effective at sealing against moisture ingress. This is because a chemical bond in this area is not normally possible due to the very high amount of elastic movement that takes place, particularly in the relatively soft outer cover, during use of the roll. The imperfect seal provided by the end shroud becomes more problematic the thinner the outer layer of the roil is.

It is a preferred object of the present invention to provide an improved de-watering roil.

According to the present invention, there is provided a de-watering roil having a shaft, a resilient sub-layer provided around the shaft, and a resilient outer cover provided around the sub-layer, the sub-layer having a hardness greater than the hardness of the outer cover, wherein a circumferential groove is formed in the sub-layer, the groove being substantially filled by the outer cover.

Preferably, said groove is formed in a region of the sub-layer adjacent an end of the roll. Advantageously, said groove is spaced inwardly of the end edge of the sub-layer. Conveniently, said groove is spaced inwardly of the end edge of the sub-layer by a distance of between 10mm and 20mm. In a preferred embodiment, the groove is spaced inwardly of the end edge of the sub-layer by a distance of 15mm.

Preferably, said groove has a radial depth of between 1 mm and 4mm, and most preferably of 2.5mm.

Advantageously, said groove has a minimum axial width of between 10mm and 20mm, and most preferably 12mm.

Conveniently, said groove has a tapered radial cross-sectional profile which narrows in a radially outwards direction.

Preferably, the radial cross-sectional profile of the groove is generally dovetail-shaped.

Alternatively, the radial cross-sectional profile of the groove is substantially rectangular.

Advantageously, the roll has a said groove at each end of the roll.

Conveniently, the sub-layer is relatively thick, and the outer cover is relatively thin.

Preferably, the radial thickness of the outer cover is approximately equal to 10% of the radial thickness of the sub-layer.

Advantageously, the sub-layer has a radial thickness of between 10mm and20 mm. in a preferred embodiment, the sub-layer has a radial thickness of 12 mm.

Conveniently, the outer cover has a radial thickness of between 1 mm and 3mm. in a preferred embodiment, the outer cover has a radial thickness of 2mm.

Preferably, the sub-layer is formed from material having a Shore D hardness of between 60 and 95.

Advantageously, the sub-layer is formed from material having a Shore D hardness of between 80 and 90.

Conveniently, the sub-layer is formed from material having a Shore D hardness of at least 85. Preferably, the outer cover is formed from material having a Shore A hardness of between 60 and 80.

Advantageously, the outer cover is formed from material having a Shore A hardness of between 65 and 75.

Conveniently, the outer cover is formed from material having a Shore A hardness

substantially equal to 70.

Preferably, the sub layer and the outer cover are each formed from an elastomeric material.

Advantageously, the sub-layer and the outer cover are each formed from a respective material selected from the group comprising nitrile rubber, polyurethane rubber, CSPE, EPDM, and HNBR.

Conveniently, the roll has an overall diameter of between 250mm and 400mm.

Preferably, an additional circumferential groove is formed in the shaft and is substantially filled by the sub-layer.

Advantageously, said additional groove is provided in axial alignment with said groove, or one of said of grooves, formed in the sub-layer.

Conveniently, the roll has a said additional groove at each end of the roil, each said additional groove being axiaily aligned with a respective said groove formed in the sub-layer.

Preferably, the or each said additional groove formed in the shaft is substantially identical in radial cross-section to the or each said groove formed in the sub-layer.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, an embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a squeeze roil in accordance with the present invention;

Figure 2 is a transverse cross sectional view taken through an end region of the roll, along line ll-il illustrated in figure 1 ; Figure 3 is a longitudinal cross-sectional view taken through the end part of the roll's central shaft, along line HI-HI illustrated in figure 2, and showing shaft prior to application of the resilient layers;

Figure 4 is a longitudinal cross-sectional view similar to that of figure 3, but which shows a resilient sub-layer applied over and around the central shaft; and

Figure 5 is another longitudinal cross-sectional view similar to that of figures 3 and 4, showing the complete roll, including an outer cover provided over and around the sub-layer.

Referring initially to figure 1 , there is illustrated a de-watering squeeze roll 1 in accordance with the present invention. The roll comprises an elongate central shaft 2 which is typically made from solid metal, and most preferably steel. The shaft 2 has a short journal section 3 provided at each end, the journal sections 3 being configured for engagement with, and support by, a cooperating bearing provided in a de-watering machine (not shown). It is to be appreciated that the shaft 2 can be .made either from solid metal, tubular metal, or in a form comprising a solid metal core provided within an overhanging metal tube, as is known for use in providing a variable pressure roll or an anti-deflection roll. Alternatively, the shaft 2 can be made from composite materials such as carbon fibre material.

Between the two journal sections 3, the shaft 2 has an elongate central section 4 of substantially uniform circular cross section. As illustrated most clearly in figures 2 and 3, a shallow circumferential groove 5 is formed in the shaft 2, the groove extending

circumferentially around the central section 4 of the shaft. As can be seen in figure 3, the circumferential groove is provided. generally adjacent, but spaced inwardly a short distance from the end of the central section 4. The groove is preferably spaced inwardly from the end of the central section by a distance of between 10mm and 20mm, and most preferably by a distance of 15mm. It is to be appreciated that the shaft is preferably provided with a substantially identical groove at its opposite end (not shown).

As shown in figure 3, the groove 5 has a substantially uniform tapered radial cross-sectional profile which narrows in a radially outwards direction, such that its base 6 represents its widest point. More particularly, it will be noted that the preferred cross-sectional profile illustrated in figure 3 is generally dovetail-shaped, having two inwardly directed opposing sidewalls 7. The groove 5 preferably has a minimum axial width w_{1 ;} measured axially between the tops of the sidewa!ls 7 at the narrowest part of the groove, of between 10mm and 20mm, and most preferably of approximately 12mm, The maximum axial width of the groove, measured axially along the base 6 of the groove at its widest point, is preferably approximately 2mm wider than w_{1 ;} and so in the most preferred embodiment Wj is 14mm. The radial depth di of the groove 5 is preferably between 1 mm and 4mm, with the most preferred depth being 2.5mm.

As illustrated in figures 1 , 2 and 4, a resilient sub-layer 8 of eiastomeric material is provided around the central roil section 4 of the shaft 2, the resilient sub-layer 8 thus having a substantially tubular configuration. The resilient sub-layer 8 can be formed from any convenient eiastomeric material, such as those typically used in conventional squeeze roll technology. However, for the purposes of the present invention, it is preferred that the eiastomeric material of the sub-layer 8 be selected from the group comprising nitrite rubber, polyurethane rubber, chlorosulfonated polyethylene (CSPE) (commonly known by the trade mark Hypalon), ethylene propylene diene M-ciass rubber (EPDM), and hydrogenated nitriie butadiene rubber (HNBR).

The resilient sub-layer 8 is configured so as to have a Shore D hardness of between 60 and 95, but more preferably to have a Shore D hardness of between 80 and 90. It has been found that the squeeze roil of the present invention performs most effectively when the sublayer is formed from material having a Shore D hardness of at least 85. As illustrated in figure 4, the material of the sub-layer 8 substantially fills the circumferential groove 5 formed around the central section 4 of the shaft 2. The region of the sub-layer 8 which fills the groove 5 can thus be considered to represent a tenon, and the groove 5 itself can be considered to represent a mortise such that the material of the sub-layer is securely anchored within the groove 5, thereby filling the groove around its entire circumferential extent.

As illustrated most clearly in figure 4, another shallow circumferential groove 9 is formed in the sub-layer 8, the groove 9 extending circumferentiaily around the sub-layer 8. As can be seen in figure 4, the circumferential groove 9 in the sub-layer 8 is provided generally adjacent, but spaced inwardly a short distance from the end edge of the sub-layer 8 such that it is provided in axial alignment with the groove 5 provided in the shaft 2. The groove 9 in the sub-layer is thus preferably spaced inwardly from the end edge of the sub-layer 8 by a distance of between 10mm and 20mm, and most preferably by a distance of 15mm. if is to be appreciated that the sub-layer is also preferably provided with a substantially identical groove 9 at its opposite end (not shown).

As shown in figure 4, the groove 9 in the sub-layer 8 has a radial cross-sectional profile which is generally identical to the profile of the underlying groove 5 in the shaft 2, The groove 9 in the sub-layer 8 thus also has substantially uniform tapered radial cross-sectional profile which narrows in a radially outwards direction, such that its base 10 represents its widest point. More particularly, it will be noted that the preferred cross-sectional profile illustrated in figure 4 is generally dovetail-shaped, having two inwardly directed opposing sidewails 1 1 .

The groove 9 in the sub-layer preferably has a minimum axial width w₂, measured axially between the tops of the sidewails 1 1 at the narrowest part of the groove, of between 10mm and 20mm, and most preferably of approximately 12mm. The maximum axial width W₂ of the groove, measured axially along the base 10 of the groove at its widest point, is preferably approximately 2mm wider than w₂, and so in the most preferred embodiment W₂ is 14mm. The radial depth d₂ of the groove 9 is preferably between 1 mm and 4mm, with the most preferred depth being 2.5mm. As will thus be appreciated, in the preferred arrangement illustrated in figure 4, d₁=d₂, W₁=w₂ and W₁=W₂.

A thin layer of resilient material is provided over and around the resilient sub-layer 8 in the form of a resilient outer cover 12. As can be seen from figures 2 and 5, the outer cover 12 is relatively thin in comparison to the relatively thick resilient sub-layer 8 (thickness being measured in the radial sense).

The outer cover 12 may be formed from natural rubber, but is most preferably formed from a synthetic elastomeric material such as nitrite rubber, polyurethane rubber, chlorosulfonated polyethylene (CSPE) (commonly known by the trade mark Hypaion) or etheylene propylene diene M-class rubber (EPDM).

The resilient outer cover 12 is configured so is to have a level of hardness lower than that of the underlying sub-layer 8. Accordingly, preferred embodiments of the present invention are configured such that the material of the resilient outer cover 12 has a Shore A hardness of between 60 and 80. More preferably the material of the outer cover 12 has a Shore A hardness of between 65 and 75, with a Shore A hardness of substantially equal to 70 being most preferable. The relatively thin outer cover 12, which effectively forms a thin membrane of softer rubber over the underlying sub-layer 8, may be bonded to the sub-layer 8 in calendered sheet form or tape form, or may be open cast or ribbon-flow cast in one-component or two-component form, or extruded in strip or cross-head form, or formed as a cast compound. The final choice of material used to form the outer cover 12 has been found to depend on various factors such as the running temperature, and the running pressure of the de-watering machinery, and the required level of resistance to processing chemicals and abrasion resistance.

As illustrated in figure 5, the material of the outer cover 12 substantially fills the

circumferential groove 9 formed around the sub-layer 8. The region of the outer cover 12 which fills the groove 9 can thus be considered to represent a tenon, and the groove 9 itself can be considered to represent a mortise such that the material of the outer cover 12 is securely anchored within the groove 9, thereby filling the groove around its entire

circumferential extent, in a generally similar manner to that in which the material of the sublayer 8 fills the groove 5 provided around the shaft 2.

Turning now to consider figure 2, D denotes the overall diameter of the squeeze roll 1 , T denotes the radial thickness of the resilient sub-layer 8, and t denotes the radial thickness of the resilient outer cover 12. it is envisaged that most practical embodiments of the squeeze roll of the present invention will have an overall diameter D of between 250mm and 400mm. The thickness T of the resilient sub-layer 8 is between 10mm and 20mm, with the relatively thin resilient outer cover 12 having a thickness t of less than or equal to 2mm. Most preferably, the outer cover 12 has a thickness t of between 1 mm and 2mm. As will therefore be appreciated, preferred embodiments of the squeeze roll have an outer cover 12 which is approximately equal in thickness to 10% of the thickness of the under lying sub-layer 8.

A squeeze roll in accordance with the preferred embodiment of the present invention, where the relative thicknesses of the sub-layer 8 and the outer cover 12 are provided in the ratio described above, with the sub-layer 8 having a Shore D hardness substantially equal to 85 and the outer cover 12 having a Shore A hardness substantially equal to 70, has been found to have an effective Shore A hardness of the combination of the two layers falling in the range of 70 to 78. The above-described squeeze roll 1 of the present invention has been found to provide very good de-watering performance when used to squeeze liquid from wet textiles. This performance arises because the softer outer cover 12 is sufficiently resilient to conform closely to the textured surface of the fabric, thereby squeezing liquid out of cavities between the warp and weft yarns of the fabric or between the surface contours of the fabric. Also, the relatively thin and softer outer cover 12 provides a surface top layer that is more deformable than conventional single-layer rubber covered squeeze roils and thus increases the efficiency of the squeezing nip between two such rollers by effectively increasing the area of contact between the two rollers and the fabric with minimum loss of nip force. The relatively softer outer cover 12 also gives the added advantage of squeezing the textile fabric more gently than would be the case with prior art rubber coated squeeze rolls having a significantly harder outer surface.

However, the relatively hard and thick underlying sub-layer 8 plays an important role in the improved performance of the squeeze roll 1 of the present invention because it retains sufficient resilience to provide sufficient squeezing force. Effectively, therefore, the softer outer cover 12 is provided to gently and closely conform to the textile fabric passing the roll, whilst the underlying relatively hard sub-layer 8 supports the thin outer cover 12 to provide sufficient squeezing force.

The performance of de-watering squeeze rolls and associated machinery is generally expressed as a percentage weight of the dry fabric. For example, if a sample of dry fabric weighs 10OOg, and after squeezing the weight of wet fabric is found to be 1500g, the level of expression achieved is said to be 1500/1 OOOg = 50%.

Squeeze rolls in accordance to the present invention have been found to provide increased squeezing performance of between 10 to 50% (averaging 30%) depending upon the type of fabric processed.

Furthermore, the provision of the circumferential groove 9 in the material of the sub-layer 8, with the material of the outer cover 12 substantially filling the groove 9 not only serves to securely anchor the two layers together in the end regions of the roll, but also importantly creates an obstacle to the flow or movement of moisture along the interface between the sub-layer 8 and the outer cover 12. The groove 9 and the material of the outer cover 12 filling it, thus serves to prevent, or at least minimize, significant penetration of water or moisture between the sub-layer 8 and the outer cover 12. This means that the bond between the two layers is more effectively protected than in prior art roll arrangements which solely on the provision of end shrouds as discussed above.

Similarly, the circumferential groove 5 provided in and around the central section 4 of the shaft 2, being substantially filled by the material of the sub-layer 8 not only serves to securely anchor the sub-layer to the shaft in the end regions of the roil, but also creates a similar obstacle to the flow or movement of moisture along the interface between the sub-layer 8 and the shaft 2, The groove 5 and the material of the sub-layer 8 filling if, thus serves to prevent, or at least minimize, significant penetration of water or moisture between the sublayer 8 and central shaft 2 of the roll 1 .

Whilst the invention has been disclosed above with specific reference to an embodiment having grooves 5, 9 with a tapered radial cross-sectional profile of dovetail form, it is to be appreciated that other embodiments could be provided with one or more grooves 5, 9 with alternative profiles in radial cross-section. For example, in a simple proposal it is envisaged that the grooves 5, 9 could each be shaped so as to have a uniform rectangular radial cross- sectional profile in which the opposing side wails 7, 1 1 are substantially parallel to one another and orthogonal to the longitudinal axis of the roil. Whilst such a groove configuration may contribute less to the secure anchorage of the sub-layer 8 to the central shaft 2, or the outer cover 12 to the sub-layer 8, it will still create an obstacle to the axial flow or movement of moisture along the respective interface.

A roll in accordance with the present invention can be used in conjunction with a

conventional steel roil or a conventional rubber covered squeeze roll in order to define a nip between the two roils, although optimum performance will be obtained by running two squeeze roils in accordance with the present invention in combination with one another.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or integers.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

Claims

1 . A de-watering roil having a shaft, a resilient sub-layer provided around the shaft, and a resilient outer cover provided around the sub-layer, the sub-layer having a hardness greater than the hardness of the outer cover, wherein a circumferential groove is formed in the sub-layer, the groove being substantially filled by the outer cover.

2. A roll according to claim 1 , said groove being formed in a region of the sub-layer adjacent an end of the roll.

3. A roll according to claim 2, said groove being spaced inwardly of the end edge of the sub-layer.

4. A roll according to claim 3, said groove being spaced inwardly of the end edge of the sub-layer by a distance of between 10mm and 20mm.

5. A roll according to any preceding claim, said groove having a radial depth of between 1 mm and 4mm.

6. A roll according to any preceding claim, said groove having a minimum axial width of between 10mm and 20mm.

7. A roll according to any preceding claim, said groove having a tapered radial cross- sectional profile which narrows in a radially outwards direction.

8. A roll according to claim 7, wherein the radial cross-sectional profile of the groove is generally dovetail-shaped.

9. A roll according to any one of claims 1 to 6, wherein the radial cross-sectional profile of the groove is substantially rectangular.

10. A roll according to any preceding claim, comprising a said groove at each end of the roil.

1 1 . A roll according to any preceding claim, wherein the sub-layer is relatively thick, and the outer cover is relatively thin.

12. A roll according to claim 1 1 , wherein the radial thickness of the outer cover is

approximately equal to 10% of the radial thickness of the sub-layer.

13. A roll according to any preceding claim, wherein the sub-layer has a radial thickness of between 10mm and 20 mm.

14. A roil according to any preceding claim, wherein the outer cover has a radial thickness of between 1 mm and 3mm.

15. A roil according to any preceding claim, wherein the sub-layer is formed from material having a Shore D hardness of between 60 and 95.

16. A roll according to any preceding claim, wherein the outer cover is formed from

material having a Shore A hardness of between 60 and 80.

17. A roll according to any preceding claim, wherein the sub-layer and the outer cover are each formed from an eiastornerie material.

18. A roll according to any preceding claim, wherein the sub-layer and the outer cover are each formed from a respective material selected from the group comprising nitrile rubber, poiyurethane rubber, CSPE, EPDM, and HNBR.

19. A roll according to any preceding claim having an overall diameter of between 250mm and 400mm.

20. A roll according to any preceding claim, wherein an additional circumferential groove is formed in the shaft and is substantially filled by the sub-layer.

21 . A roll according to claim 20, wherein said additional groove is provided in axial

alignment with said groove, or one of said of grooves, formed in the sub-layer.

22. A roll according to claim 21 , as dependent upon claim 10, having a said additional groove at each end of the roll, each said additional groove being axiaily aligned with a respective said groove formed in the sub-layer.

23. A roll according to any one of claims 20 to 22, wherein the or each said additional groove formed in the shaft is substantially identical in radial cross-section to the or each said groove formed in the sub-layer.

24. A roll substantially as hereinbefore described with reference to and as shown in the accompanying drawings.