GB2241968A

GB2241968A - Calender arrangement

Info

Publication number: GB2241968A
Application number: GB9005807A
Authority: GB
Inventors: Stanley John Heal; Nigel Ashworth
Original assignee: Hunt and Moscrop Ltd
Current assignee: Voith Paper Ltd
Priority date: 1990-03-15
Filing date: 1990-03-15
Publication date: 1991-09-18
Also published as: GB9005807D0

Abstract

A calender arrangement for calendering paper comprises two pairs of rolls 12, 14 forming nips 32, 34 and a guide arrangement 38 for guiding paper which has passed through nip 32 into nip 34 in either one of two directions e.g. along either route A or route B. The direction of rotation of each of the rolls of roll pair 14 is reversible. One roll in either one or both pairs of rolls may be soft and the other hard, or both rolls in one pair may be soft or hard, or the rolls in both pairs may be soft. Each roll may be a controlled deflection roll and each hard roll may be heated. The paper calendered may be supplied from a papermaking machine or a paper coating machine. A range of finishes e.g. gloss or matt of different degrees may be imparted to one or both surfaces of paper. <IMAGE>

Description

IMPROVEMENTS IN OR RELATING TO CALENDER ARRANGEMENTS The present invention relates to calender arrangements for example calender arrangements for treating the surface of a web material such as paper. In particular the invention relates to a calender arrangement comprising a number of hard and soft rolls or soft rolls only arranged to impart a range of finishes to one or both surfaces of the paper web. The finishes can comprise matt and gloss finishes of different degrees of finish.

In the context of calender arrangements the terms 'hard' and 'soft' are relative terms. A hard roll can comprise a chilled iron roll, a steel roll or a roll of other suitable material, having a ground outer surface for contact with the paper web and a soft roll can comprise a cast iron shell covered with a plastics material or a compressed textile fibre material.

Finishes are applied to either or both surfaces of a paper web by passing the web through the nip between a pair or pairs of adjacent rolls. The rolls in each pair can comprise either a soft roll and a hard roll, two soft rolls, or two hard rolls depending on the type and degree of finish required. The surface of the paper web adjacent the hard roll is given a gloss finish, and the surface of the paper web adjacent the soft roll is given a matt finish. The degree of both gloss and matt finish can be varied by adjusting factors such as the nip pressure, web feed speed, the temperature at the nip and the number of passes through different nips.

The hard rolls or some of them can be heated using a medium, such as steam or heated oil, or induction heating, and the soft rolls or some of them can be controlled deflection rolls.

The rolls whether hard or soft control deflection or heated are expensive components of calender arrangements. It is desirable that the number of rolls is kept to a minimum in order to achieve the required finish on one or both surfaces of a paper web at the lowest cost. Usually however, if the number of rolls is kept to a minimum the range of finishes which can be applied to the paper surfaces is limited due mainly to constraints on the direction of that the paper web can take through a succession of nips.

The present invention seeks to provide a calender arrangement which can provide a wide range of finishes to a paper web in relation to the number of rolls used in the calender arrangement.

Accordingly the present invention provides a calender arrangement for treating a web of material, the arrangement comprising two pairs of rolls, the two rolls in each pair defining a nip through which the web of material can pass, the web of material passing in use through the two nips in succession, guide means for the web material located adjacent at least one of said pair of rolls, the guide means being arranged so that the web of material can pass through the nip of the said at least one pair of rolls in either one of two directions, and drive means for each pair of rolls, the drive means for the said at least one pair of rolls being arranged to drive the said at least one pair of rolls in either one of two directions.

The rolls in one or both pairs of rolls can be located vertically one above the other or adjacent one another in a side by side relationship.

The guide means can comprise at least two rollers enabling the web material to pass through the nts of one or both pairs of rolls in either one of the two directions.

At least one roll in each pair of rolls can be moveably mounted to vary the nip between the rolls in each pair. One roll in one pair or both pairs of rolls may be a soft roll and one roll in one pair or both pairs of rolls may be a hard roll. Both rolls in one pair of rolls can either be soft rolls or hard rolls, and the rolls in both pairs of rolls can be soft rolls.

Each soft roll can be a control deflection roll and each hard roll can include heating means.

The soft rolls can have a hardness of between 80 and 94 Shore D.

In one arrangement according to the present invention a calender arrangement comprises a soft roll and a hard roll arranged vertically with respect to one another and a further soft roll and a hard roll arranged horizontally in a side by side relationship with respect to one another, the centres of rotation of the rolls in the second pair of rolls being horizontally aligned with the nip between the first pair of rolls.

Both soft and hard rolls can be control deflection rolls and in the case of the first pair of rolls the soft roll can be located either vertically bove or below the hard roll.

The hard or soft roll in each pair of rolls can be pivotally mounted and the nip adjusted using one or more hydraulic or pneumatic actuators to pivotally move the hard roll towards or away from the soft roll.

Each hard roll can be provided with heating means using a heated medium such as steam or oil, or induction heating.

The present invention will now be more particularly described with reference to the accompanying drawings in which Fig. 1 shows a side elevation of one form of calender arrangement according to the present invention, and Figs. 2-8 inclusive illustrate diagrammatically further calender arrangements in accordance with the present invention.

Referring to Fig. 1 there is shown a calender arrangement 10 comprising two pairs of rolls 12 and 14. Each pair of rolls comprises a hard roll 12A, 14A respectively and a soft roll 12B, 14B respectively.

The pair of rolls 12 is mounted on a support structure 16 and the pair of rolls 14 is mounted on a support structure 18. In both cases the soft rolls 12B and 14B are fixedly mounted to their respective support structures such that their centres of rotation remain fixed in relation to the respective support structures.

Similarly in both cases the hard rolls are fixedly secured to beams 20 and 22 respectively which are pivotted on axes 24 and 26.

The beams are pivotally moved by means of one or more hydraulic jacks 28 and 30.

A nip 32 is provided between the rolls 12A and 12 B and a nip 34 is provided between the rolls 14A and 143. A web of paper 36 is arranged to be fed for example from a paper making machine (not shown) and passes through the nip 32 and then follows either a route A or a route B through the nip 34. A arrangement of rollers which comprises a guide means 38 defines the routes A and B.

Route A is defined by rollers 40, 42, 44, 46 and a roller 48 which is common to both routes. Route B is defined by rollers 50, 52, 54, 56 and the roller 48. The number of rollers required to guide the paper web through a calender arrangement according to the present invention will depend on the conditions at the location of the calender. For example, the space available, the difference between the height at the input to the calender and the output from a prior machine, eg a paper making or coating machine, and the difference between the height between the output of the calender and the subsequent machine or store.

A surface of a paper web in contact with a hard roll in a calender tends to be smoothed and be given a gloss finish, whilst a surface in contact with a soft roll tends to be given a matt or satin finish due to the resilience of the soft roll. As the soft roll can be varied in resilience by the use of different covers, the degree of matt or satin finish can be varied.

Prior to entry to the calender, the paper web can be supplied directly from a paper making machine, or a paper coating machine.

Thus, the paper web prior to being calendered can have the same finish on both surfaces, or a different finish on each surface.

The present invention provides the capability of a wide range of calendering operations which can be performed on a paper web having the same, or different finishes on its opposed surfaces.

The terms 'gloss' and 'matt' are relative terms and can be measured by measuring the reflectivity of the paper surfaces. For the purpose of this specification, a surface in contact with a hard roll is deemed to be given a gloss finish, and a surface in contact with a soft roll is deemed to be given a matt finish. If the same surface is in contact with two rolls of the same type in succession it is deemed to have been given a double finish, while if in contact with only one roll, it is deemed to have been given a single finish.

The paper web 36 has two surfaces 36A and 36B and if it is desired to use the calender arrangement 10 to provide a double matt finish on surface 36A and a double gloss finish on surface 36B, the paper web 36 has to follow route A through the nip 32, over the rollers 40, 42, 44, through the nip 34 and over the rollers 46 and 48.

The paper web can be initially threaded through the calender arrangement by any appropriate technique. For example, the use of pairs of ropes.

The hydraulic jacks 28 and 30 are operated to create the required nips 32 and 34. Also if either or both of the soft rolls 12B and 14B are controlled deflection rolls they can also be operated to exert a load as required. Either or both of the hard rolls 12A and 12B can be provided with heating means (not shown) for example, a supply of a heated medium such as steam or oil so as to provide heat to a desired temperature at either or both nips.

The paper web 36 is driven through the calender arrangement 10 by virtue of the respective drive means of the rolls pairs 12 and 14 driving the rolls in the direction of arrows C and D. It will be appreciated that as the surface 36B of the paper web is in contact with the hard roll 12A a gloss finish will be imparted to the surface 36B as it passes through the nip 32. The same surface 36B is in contact with the hard roll 14A and therefore a double gloss finish will be imparted to the surface 36B as it passes through the nip 34. The other surface 36A is in contact with both of the soft rolls 12B and 14B, and therefore a double matt finish is imparted to the surface 36A of the paper web as it passes through the calender arrangement following route A.This arrangement provides a double gloss finish to one side of the paper web and a double matt finish to the other side of the paper web.

If it is desired that a single finish is applied to both surfaces of the paper web the paper web is passed through the machine so that it follows route B, that is through the nip 32 and over the rollers 50, 52, 54, 56 and the roller 48 which is common to both routes. In this case again the surface 36B will receive a gloss finish as it passes through the nip 32 and as the web passes through the nip 34, the surface 36A is in contact with the hard roll 14A and a single gloss finish will be imparted to the surface 36B. This arrangement provides a single finish to both sides of the paper web.

The degree of gloss or matt finish can be varied by varying such.

factors as the rate at which the paper web is fed through the calender, the temperature at the nip, the pressure applied at the nip and the degree of resilience of the soft roll.

Referring to Figs. 2 to 8 inclusive in which the same references have been used for components shown in Fig. 1, Figs 2A and 2B correspond to Fig. 1 showing routes A and B respectively for the paper web 36. The rolls 12A and 12B are shown vertically disposed with the soft roll 12B vertically above the hard roll 12A and the rolls 14A and 14B are shown horizontally arranged in a side by side relationship. However the vertical relationship of the rolls 12A and 12B can be reversed as shown in Figs. 2C and 2D.

In Fig. 2C, the web 36 follows route B and a double finish is given to both sides of the paper web, whilst in Fig. 2D, a single finish is given to both sides of the paper web.

Referring to Figs. 3A and 3B the rolls in the first pair 12 are in the same position as in Fig. 1, and the rolls in the second pair 14 are shown reversed in position.

Referring to Figs. 3C and 3D the position of the rolls in the pair of rolls 14 is the same as in Figs. 3A and 3B but the position of rolls 12A and 12B have been reversed. Again the guide means 38 provides that the paper web can follow either route A or route B.

Referring to Fig. 4 which shows all of the rolls in both pairs arranged in a side by side relationship, the guide means 38 again provides an arrangement of rollers so that the paper web can follow either route A or route B. It will be noticed that in the case of Figs. 4A and 4B the paper web is fed down into the nip 32, whilst in Figs. 4C and 4D the paper web is fed upwardly through the nip 32 and the guide means 38 again allows the paper web to follow either route A or route B.

Referring to Fig. 5 both of the rolls 12A and 12B are hard rolls so that one side of the paper web has a single finish whilst the other side of the web has a double finish.

Referring particularly to Figs. 5A and 5B the rolls 14A and 14B are in the same position as shown in Fig. 1 whilst in Figs. 5C and 5D the position of the rolls 14A and 14B have been reversed.

Again the guide means 38 provides that the paper web can follow either one of two routes C or D via the guide means 38.

Referring to Fig. 6 in which both of the rolls in the roll pair 12 are soft rolls.

In Figs. 6A and 6B the rolls 14A and 14B are in the same position as shown in Fig. 1 and the guide means 38 provide that the paper web can follow either a route E or a route n. In Figs. 6A and 6B the paper web can receive a single gloss finish on one surface and a double matt finish on the opposite surface.

Referring to Figs. 6C and 6D the position of the rolls 14A and 14B have been reversed so that the finishes on the surfaces of the paper web have been reversed.

Fig. 6 shows the rolls in the roll pair 12 to be both soft rolls.

The rolls in roll pair 14 can also both be soft rolls, so that the calender arrangement can comprise two pairs of soft rolls, the guide means 38 and a drive arrangement for each pair of rolls.

The guide means 38 is arranged to drive a paper web through the nip of one of the pair of rolls in either one of the two directions available.

The hardness of the rolls can be chosen so both of the rolls in a pair are of the same hardness as each other or of different hardness. The rolls in one roll pair can be of a different hardness to the rolls in the other roll pair.

The direction of movement of the paper web through all of the calender arrangements shown in Figs. 2-6 have been indicated by the arrow but it is to be understood that the direction of the paper web can be reversed and the paper web fed through the calender arrangement in the opposite direction to that indicated.

Referring to Figs. 7 and 8 in all cases both pairs of rolls 12, 14 are horizontally arranged in a side by side relationship, and the guide means 38 are arranged to guide the paper web 36 through the nips 32, 34 in either one of two directions A and B.

Referring to Figs. 7A and 7B the paper web is fed downwardly through the nip 32 whilst in Figs. 7C and 7D the paper web is fed upwardly through the nip 32.

In all cases the guide means 38 is arranged so that the paper web can follow either route A or route B. The paper web receives a double gloss finish on one side and a double matt finish on the opposite side when the following route B and single gloss and a single matt finish on its surfaces when following route A.

Referring to Fig. 8 again the rolls in each pair of rolls are arranged horizontally in a side by side relationship. In Figs. 8A and 8B the paper web is fed downwardly into the nip 32 whilst in Figs. 8C and 8D the paper web is fed upwardly through the nip 32.

In Figs. 8A and 8D the paper web receives a double finish on each side and in Figs. 8B and 8C the paper web receives a single finish on both sides.

The guide means 38 shown in Figs. 2 to 8 inclusive are only indicated diagramatically. It will be understood that in all cases the guide means can comprise the number of rollers necessary to guide the paper web in the desired direction, into, through and out of the calender arrangement.

The hard rolls as well as the soft rolls can be controlled deflection rolls, and the soft rolls as well as the hard rolls can be pivotally mounted in a manner similar to the hard rolls.

It will be appreciated that calender arrangements according to the present invention by the use of only four rolls together with appropriate guide means can provide a range of finishes on either or both surfaces of a paper web depending on the direction of feed of the web through the nips between adjacent rolls.

Arrangements according to the present invention are readily adaptable to meet the finish requirements as the paper web only has to be passed through the machine in either one of two directions and the amount of time required to reverse the direction of rotation of either pair of rolls is relatively low.

Also the rolls are readily maintained but more importantly the number of rolls required is reduced as compared to existing calender arrangements.

Claims

1 A calender arrangement for treating a web of material, the arrangement comprising two pairs of rolls, the two rolls in each pair defining a nip through which the web of material can pass, the web of material passing in use through the two nips in successior., guide means for the web material located adjacent at least one of said pair of rolls, the guide means being arranged so that the web of material can pass through the nip of the said at least one pair of rolls in either one of two direction, and drive means for each pair of rolls, the drive means for the said at least one pair of rolls being arranged to drive the said at least one pair of rolls in either one of two directions.

2 A calender arrangement as claimed in claim 1 in which the rolls in at least one of the said pairs of rolls are arranged in a side by side horizontal relationship.

3 A calender arrangement as claimed in claim 1 or claim 2 in which the rolls in one pair of rolls are arranged vertically one above the other.

4 A calender arrangement as claimed in claim 2 in which both pairs of rolls are arranged in a side by side relationship.

5 A calender arrangement as claimed in any one of the preceding claims in which at least one roll in one of said pairs is a soft roll.

6 A calender arrangement as claimed in claim 5 in which at least one of the rolls in one of the pair of rolls is a hard roll.

7 A calender arrangement as claimed in claim 5 in which one pair of rolls comprises a soft roll and a hard roll.

8 A calender arrangement as claimed in claim 7 in which both pairs of rolls comprise a soft roll and a hard roll.

9 A calender arrangement as claimed in claim 5 or claim 6 in which one pair of rolls comprises a soft roll and a hard roll and the other pair of rolls comprises two hard rolls.

10 A calender arrangement as claimed in claim 5 or claim 6 in which one pair of rolls comprises a soft roll and a hard roll and the other pair of rolls comprises two soft rolls.

11 A calender arrangement as claimed in claim 5 in which both rolls in each pair comprise soft rolls.

12 A calender arrangement as claimed in any one of the preceding claims in which the guide means comprises a plurality of rollers, one or more of said rollers defining a first route for the material web to follow and at least one roller defining a second route for the web material to follow.

13 A calender arrangement as claimed in claim 12 in which the first route is defined by three rollers located between the first and second nips and at least one roller located after the second nip.

14 A calender arrangement as claimed in claim 12 in which the second route is defined by at least two rollers located between the first and second nips and at least two rollers located after the second nip.

15 A calender arrangement as claimed in claim 12 including a roller located after the second nip common to both first and second routes.

16 A calender arrangement as claimed in claim 12 in which the roller arrangement is arranged to guide the paper web through the nip of both said pairs of rollers.

17 A calender arrangement as claimed in any one of the preceding claims in which any one of the rolls comprises a controlled deflection roll.

18 A calender arrangement as claimed in any one of the preceding claims in which any one of the hard rolls includes heating means.

19 A calender arrangement constructed and arranged for use and operation substantially as herein described and with reference to the accompanying drawings.