WO2011089374A1

WO2011089374A1 - Improvements in or relating to rolls

Info

Publication number: WO2011089374A1
Application number: PCT/GB2010/001930
Authority: WO
Inventors: Anthony John Ashton
Original assignee: Richard Hough Limited
Priority date: 2010-01-25
Filing date: 2010-10-19
Publication date: 2011-07-28
Also published as: GB2477157A; GB201001194D0

Abstract

There is disclosed a de-watering roll, and an apparatus comprising such a roll, particularly suitable for use in the textile industry. The roll comprises a shaft (2) and a thin, resilient cover (5) provided around the shaft. The hardness of the shaft is in the range 20 to 600 Brinell, and the hardness of the cover is in the range 50 to 70 Shore A.

Description

IMPROVEMENTS IN OR RELATING TO ROLLS

The present invention relates to a roll and an apparatus comprising such a roll. The invention relates particularly to a squeeze roll and related apparatus suitable for use in the textile industry.

It is known in the textile industry to use squeeze rolls 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.

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 elastomeric substances such as nitrile.

In a typical de-watering machine such as a mangle, two squeeze rolls 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 as the resilient material provided around the central shaft of the roll deforms slightly under the squeezing pressure applied to the roll, 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 rolls 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 .

It is therefore an object of the present invention to provide an improved squeeze roll.

According to a first aspect of the present invention, there is provided a de-watering roll comprising a shaft and a resilient cover provided around the shaft, the shaft having a hardness greater than the hardness of the cover, wherein the cover has a radial thickness of between 0.5mm and 3mm and is formed from a single layer of material having a Shore A hardness of between 50 and 70.

Preferably, the cover has a radial thickness substantially equal to 2mm. Conveniently, the cover is formed from an elastomeric material .

Preferably, the cover is formed from a material selected from the group comprising nitrile, CSPE, EPDM, polyurethane, and HNBR.

Advantageously, the shaft is solid. Alternatively, the shaft is hollow.

Preferably, the shaft is formed from a material having hardness in the range 20 to 600 Brinell.

Advantageously, the combination of the shaft and the cover ha a Shore D hardness in the range 70 to 75.

Preferably, the combination of the shaft and the cover has a Shore D hardness substantially equal to 73.

Advantageously, the squeeze roll has an overall diameter of between 250mm and 600mm

Conveniently, the cover has a substantially constant thicknes over substantially its entire extent.

According to another aspect of the present invention, there i provided an apparatus for squeezing liquid from textiles, the apparatus comprising at least one roll of the type defined above .

Preferably, the apparatus comprises at least one pair of roll of the type defined above, wherein each said roll is arranged to run against the other said roll. So that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments 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 roll according to the present invention;

Figure 2 is a transverse cross sectional view taken through the squeeze roll illustrated in figure 1.

Referring initially to figure 1, there is illustrated a 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 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 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. At least the central section 4 of the shaft 2 is formed from material having a hardness of between 20 to 600 Brinell .

A thin layer of resilient material is provided over and around the central section 4 of the shaft 2 in the form of a

resilient cover 5. As can be seen from figure 1, the cover 5 is relatively thin in comparison to the shaft 2 (thickness being measured in the radial sense) .

The cover 5 may be formed from natural rubber, but is most preferably formed from a synthetic elastomeric material such as nitrile rubber, polyurethane rubber, chlorosulfonated polyethylene (CSPE) (including "Hypalon" and "Super Dynamic", both of which are trade marks for particular forms of CSPE) , ethylene propylene diene M-class rubber (EPD ) or hydrogenated nitrile butadiene rubber (HNBR) . The final choice of material used to form the cover 5 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.

The resilient cover 5 is configured so as to have a level of hardness lower than that of the shaft 2. Accordingly,

preferred embodiments of the present invention are configured such that the material of the resilient cover 5 has a Shore A hardness of between 50 and 70. Preferably, the cover 5 has a Shore A hardness substantially equal to 65.

The relatively thin cover 5, which effectively forms a thin membrane of softer rubber over the shaft 2, may be bonded to the shaft 2 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.

Turning now to consider figure 2, D denotes the overall diameter of the squeeze roll 1, and t denotes the radial thickness of the resilient cover 5. 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 600mm. In one arrangement of the present invention, the roll has an overall diameter D of between 250mm and 400mm. The thickness t of the resilient cover 5 is between 0.5mm and 3mm. Typically, the cover 5 has a thickness t of 2mm.

A squeeze roll in accordance with the preferred embodiment of the present invention with a shaft having a hardness in the range of 20 to 600 Brinell and a cover having a thickness substantially equal to 2mm and a hardness substantially equal to 65 Shore A, has been found to have an effective overall Shore D hardness in the range of 70 to 75. Preferably, the effective overall hardness is substantially equal to 73 Shore D.

The above-described squeeze roll 1 of the present invention has been found to provide significantly improved de-watering performance when used to squeeze liquid from wet textiles. This increased performance arises because the soft cover 5 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. The relatively soft cover 5 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 shaft 2 plays an important role in the improved performance of the squeeze roll 1 of the present invention because it retains a sufficient overall hardness of the roll to provide sufficient squeezing force. Effectively, therefore, the softer cover 5 is provided to gently and closely conform to the textile fabric passing the roll, whilst the underlying relatively hard shaft 2 supports the thin cover 5 and provides sufficient squeezing force . It is known that widening the squeezing nip line area between two rollers generally worsens the squeezing effect.

Accordingly, the present invention maintains a high

concentration of pressure in a narrow nip line area whilst providing a surface top layer that is more deformable than prior art rubber covered squeeze rolls and thus increases the efficiency of the squeezing nip between two such rollers.

Therefore, the interaction between the softer cover 5 and the hard and thick shaft 2 provides a more efficient squeezing effect .

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 lOOOg, and after squeezing the weight of wet fabric is found to be 1500g, the level of expression achieved is said to be 1500/1000g = 50%.

Squeeze rolls according to the present invention have been found to provide increased squeezing performance over

conventional rolls generally in the range of 30 to 50% depending upon the type of fabric processed.

It is important that the cover 5 is not made too thick. It has been found through experiment that the performance

characteristics of a roll in accordance with the present invention begin to deteriorate significantly when the

thickness of the cover 5 is increased beyond 3mm.

It is known to provide squeeze rolls with a parabolically cambered profile in order to ensure substantially uniform nip pressure as the rolls bend when placed under load in the de- watering machine. It is therefore envisaged that rolls in accordance with the present invention could be configured so as to have such a profile, in which case the shaft 2 could be ground so as to have the desired parabolic camber prior to the relatively thin cover 5 being applied over the shaft 2. The cover 5 can then be applied and re-ground to adopt the same parabolic profile, thus maintaining uniform thickness over the entire extent of the cover 5.

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

In the event that the roll of the present invention is to be used for de-watering purposes in the manufacture of paper, then it is envisaged that the two-layer resilient covering would be provided with an array of holes or grooves for connection to otherwise conventional vacuum extraction

equipment .

When used in the specification and claims, the terms

"comprises" and "comprising" and variations thereof mean that the specified features, steps or components are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the forgoing description, or the following claims, or 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 roll (1) comprising a shaft (2) and a

resilient cover (5) provided over and around the shaft (2) , the shaft (2) having a hardness greater than the hardness of the cover (5) , wherein the cover (5) has a radial thickness of between 0.5mm and 3mm and is formed from a single layer of material having a Shore A

hardness of between 50 and 70.

2. A roll according to claim 1, wherein the cover (5) has a radial thickness substantially equal to 2mm.

3. A roll according to claim 1 or claim 2, wherein the

cover (5) is formed from an elastomeric material.

4. A roll according to any preceding claim, wherein the cover (5) is formed from a material selected from the group comprising nitrile, CSPE, EPDM, polyurethane, and HNBR.

5. A roll according to any preceding claim, wherein the shaft (2) is solid.

6. A roll according to any one of claims 1 to 4, wherein the shaft (2) is hollow.

7. A roll according to any preceding claim, wherein the shaft (2) is formed from a material having hardness in the range 20 to 600 Brinell.

8. A roll according to any preceding claim, wherein the combination of the shaft and the cover has a Shore D hardness in the range 70 to 75.

9. A roll according to any preceding claim, wherein the combination of the shaft and the cover has a Shore D hardness substantially equal to 73.

10. A roll according to any preceding claim having an

overall diameter of between 250mm and 600mm

11. A roll according to any preceding claim, wherein the cover has a substantially constant thickness over substantially its entire extent.

12. An apparatus for squeezing liquid from textiles, the apparatus comprising at least one roll according to any preceding claim.

13. An apparatus according to claim 12 comprising at least one pair of rolls according to any one of claims 1 to 11, wherein each said roll is arranged to run against the other said roll.

14. A de-watering roll substantially as hereinbefore

described with reference to and as shown in the accompanying drawings .