GB2079339A - Multi-ply paperboard machine - Google Patents

Abstract

Multi-ply paperboard is manufactured by forming consecutive paper plies 1-8 on individual moving fabrics. The plies are alternately mated to one side and then the next of the partly-formed paperboard. A machine for manufacturing the paperboard in this way a fabric belt 15 which passes over a set of four rolls 11, 12, 13, 14 with a first, low-vacuum box 22 to dewater the ply before it is laminated to the other plies and a second, high-vacuum box 24 to dewater the mated plies and improve the bonding between the plies. <IMAGE>

Description

SPECIFICATION Multi-ply paperboard machine This invention relates to apparatus and methods for manufacturing multiply paperboard from paper making stock. More particularly, this invention is concerned with a method for producing multiply paperboard by combining a plurality of separately formed plies as the plies and the partially produced paperboard travel in a generally downwards direction. The invention is also concerned with an apparatus for carrying out the method.

Paperboard is a widely used commercial product, both as an integral part of manufactured goods such as furniture, appliances and shelter, but also in the manufacture of storage and shipping containers and cartons.

In the manufacture of paperboard, two or more webs or plies of paper stock are formed simultane ously or sequentially on a suitable fabric belt and while still wet the plies are mated, often with pressure and an applied vacuum to cause the plies to bond together. Once all of the plies are so combined, the wet multiply paperboard is generally carried by a felt blanket to a drier where the water is evaporated and from which dry paperboard emerges. The strength of the paperboard so produced depends, to a large extent, upon the number of plies of which it is made, the thickness of the finished product and the nature of the fibrous paper stock from which the plies are made.

In one conventional method of producing multiply paperboard, the plies are added consecutively starting at the bottom and building up until all ofthe plies are laminated together. A machine used to produce paperboard in this way is generally arranged for horizontal flow of the product with the result that a long space is needed to accommodate it. In addition, as the plies are added the flow of water is usually in one direction, i.e., downwardly (as a result of gravity and vacuum applied below the paperboard), with the result that the fibers of each ply do not have much of an opportunity to penetrate into the ply immediately above.

German Patent Application No. 1,921,378 discloses a combination horizontal and vertical machine for making paperboard by building up the number of plies from the inside to the outside. The machine, however, is one which would require a large installation space. Furthermore, the water from each consecutively added new ply is not caused to flow into the previously deposited plies of the partially formed paperboard but, instead, is largely removed before that can be achieved.

U.S. patent No. 3,471,367 discloses a vertical paperboard machine in which the plies are formed and mated, with downward travel, from the inside to the outside by alternately applying an added ply to each side. After water is removed simultaneously from both sides of the partially formed product, a vacuum is applied to the side having the new ply.

The effect of this is that the water is not caused to flow from it through the other plies. In turn, this makes it more difficult to develop a good bond by increased fiber intermeshing at the mating ply surfaces.

According to the present invention, multiply paperboard is formed outwards from the inside, with multiple reversal of water flow through the plies for improved bonding. Pressure is used to adjust ply thickness and to enhance bonding and water removal. The invention employs solid or continuous surface rolls, as distinguished from vacuum rolls, and outside vacuum boxes.

Production of paperboard according to the invention can be effected in a downwardly moving, essentially vertical direction on a machine using two or more fibrous ply forming apparatus units.

It is expected that an eight-ply paperboard manufacturing machine produced according to the invention could be about 8 metres high and wide and have a length of 5 metres in the machine direction. Such a machine therefor occupies a relatively small space, thus lowering capital investment in the machine and its housing.

According to one aspect of the invention, a multiply paperboard is produced by consecutively forming a series of two or more separate paper plies on individual moving fabrics. The second formed paper ply is mated to one side of the first formed paper ply and, when more than two plies are used, the third formed paper ply is mated to the other side of the first formed paper ply. Any additional, consecutively formed paper plies are then mated first to the second ply and then to the third ply, continuing the alternate side mating of any additional plies to be deposited.

As the second and each subsequent ply is mated to the board being manufactured, water in the newly added ply is made to flow from it into and out of the one or more plies constituting the partially formed paperboard. A combination of applied vacuum and roll pressure is preferably employed to make the water flow in this way. The flow path of the paperboard being formed is preferably in a substantially downward directed vertical path.

The method can be carried out using a fibrous ply forming apparatus unit which can be assembled with one or more additional units which are essentially identical, so as to form a multiply paperboard making machine. Each unit has four horizontal, spaced-apart rolls equally spaced from a vertical plane normal to the axes of the rolls and parallel to each other. These rolls are, respectively, a tail roll, a head roll, a foot roll and a guide roll. A fibrous plyforming, endless fabric belt runs over the four rolls and a low-vacuum box is disposed beneath the run of the fabric belt extending from the tail roll to the head roll for dewatering the fibrous ply-forming material deposited on this fabric run. A high-vacuum box is positioned behind the run of the fabric belt extending from the head roll to the foot roll. Each of the rolls preferably has a solid continuous surface.

The fabric belt is arranged to run in a direction from the tail roll to the top roll.

Each unit may also include a headbox positioned to deposit a fibrous ply-forming material on the fabric belt run between the tail roll and the head roll.

To faciiitate deposition of the fibrous ply and partial water removal, the top of the tail roll is preferably arranged lower than the top of the head roll so that the fabric belt run between these two rolls is inclined.

In a particularly suitable embodiment of the mod use, the head roll is located substantially vertically above the foot roll. Also the guide roll is suitably located between the foot roll and the tail roll.

The tail roll is advisably made adjustable normal to its axis to enable the tension on the fabric belt to be altered, to apply a substantially constant pressure to the ply and forming paperboard, no matter what the thickness of the ply or paperboard. The tail roll is generally made adjustable in a plane parallel to the fabric belt run between the tail roll and the head roll so as to keep the belt in line with respect to the vacuum box between these two rolls. An air cylinder is desirably used to achieve the adjustability of the rail roll because it readily maintains a set pressure and tension on the fabric belt.

Two or more of the described units can be employed, together with a fibrous ply top holding unit and a bottom or end pressure roll to form a paperboard manufacturing machine. Such a machine comprises: A. ATop Fibrous Ply Top Holding Unit. Thisunit is similar to the forming units except, basically, it has no headbox. It comprises: (i) four horizontal, spaced-apart rolls equally spaced from a vertical plane normal to the axes of the rolls (these rolls are, respectively, a tail roll, a head roll, a foot roll and a guide roll, parallel to each other), (ii) a fibrous ply-forming endless fabric belt wound over the four rolls, (iii) a vacuum box beneath the run of the fabric belt extending from the tail roll to the head roll, and (iv) a vacuum box behind the run of the fabric belt extending from the head roll to the foot roll.

B. At least two Fabrous Ply Forming Apparatus Units. These are forming units of the type described above and are similar to the Holding Units except that appropriate headboxes for the fibrous plyforming material are provided.

In the machine, the first fibrous ply forming apparatus is positioned to have its head roll opposite the vacuum box of the holding unit and behind the run of the fabric belt extending from the head roll to the foot roll of the holding unit. Also, the foot roll of the holding unit is positioned opposite the upper portion of the high-vacuum box of the first fibrous ply forming apparatus and, finally, the foot roll of the first fibrous ply forming apparatus is positioned opposite the upper portion of the high-vacuum box of the second fibrous ply forming apparatus.

A bottom pressure roll may be provided opposite the lower portion of the high-vacuum box of the second fibrous ply forming apparatus.

A paperboard manufacturing machine according to the invention will include one ofthe fibrous ply forming apparatus units or modules for each ply to be built into the paperboard, and every other unit will be located, figuratively, on opposite sides of a more or less vertical line. The head roll and tail roll of each unit and the run of fabric belt supported by these two rolls will constitute a front face or eievation which is more or less adjacent at least a portion of the front faces of the next higher and lower units.

In a preferred embodiment of the paperboard manufacturing machine, a top holding unit is provided (of the type described above) together with a number ofthe fibrous ply forming apparatus units.

These units are positioned in a substantially vertical arrangement with the front face of every other apparatus fronting on, and being on, the same side of a line. The uppermost forming apparatus for the first fibrous ply is positioned to have its head roll opposite the vacuum box ofthe holding unit behind the run of the fabric belt extending from the head roll to the foot roll of the holding unit. The head roll of the second and any subsequent ply forming apparatus is positioned opposite the lower portion of the high-vacuum box of the next higher fibrous ply forming apparatus.

The foot roll of each fibrous ply forming apparatus, except the lowermost apparatus, is positioned opposite the upper portion of the highvacuum boxofthe next lower fibrous ply forming apparatus. A bottom pressure roll is disposed opposite the lower portion of the high-vacuum box of the lowermost fibrous ply forming apparatus.

In such a machine, it is 'advisable to have the bottom pressure roll support a paperboard pick-up felt belt blanket for transporting the formed paperboard for further, conventional processing, such as to a drier.

In a particularly useful form of machine, the axes of the head rolls and foot rolls of the holding unit and all of the fibrous ply forming apparatus are positioned to be in or close to a vertical center line.

Further features and advantages of the invention will be apparantfrom the following description of the preferred embodiments, given with reference to the accompanying drawings in which: FIGURE lisa side elevational view of the fibrous ply forming apparatus unit provided by the invention; FIGURE 2 is a side elevational view of a paperboard manufacturing machine, using two of the units illustrated by FIGURE 1, a fibrous ply top holding unit, and a bottom pressure roll; FIGURE 3 is a side view of a two-ply paperboard which can be manufactured using the machine illustrated in FIGURE 2; FIGURE 4 is a side elevational view of a paperboard manufacturing machine, using eight of the units illustrated by FIGURE 1, a fibrous ply top holding unit, and a bottom pressure roll; and FIGURE 5 is a side view of an eight-ply paperboard which can be manufactured using the machine illustrated by FIGURE 4.

So far as is practical, the same or similar elements which appear in the various views ofthe drawings are identified by the same number.

The fibrous ply forming apparatus unit 10 shown in Figure 1 has a tail roll 11, a head roll 12, a foot roll 13 and a guide roll 14. Each of the four rolls has a smooth, continuous, uninterrupted cylindrical surface. The axes of the four rolls are parallel to each other and are equally spaced from a vertical plane normal to the axes of the rolls.

Tail roll 11 is adjustably mounted so as to maintain a suitable tension on endless fabric belt 15 would over the four rolls. Thus, tail roll 11 is joined at each end to a connecting rod 18 operably associated with a piston (not shown) in air cylinder 19. The tail roll 11 is movable in a direction parallel with the run of belt 15 between the tail roll 11 and head roll 12. Guide roll 14 is also adjustably mounted so as to enable fabric belt 15 to be tensioned properly when it is initially installed on the rolls.

Positioned below the run of belt 15 between tail roll 11 and head roll 12 is a low vacuum box 22.

Behind the run of belt 15 between the head roll 12 and the foot roll 13 is a high vacuum box 24. Spray device 16 is provided to wash belt 15. A drip pan 25 is located beneath the entire unit 10 to collect water which drops from the unit during operation.

The fibrous ply forming apparatus includes a fibrous stock headbox 28 from which a fibrous ply 1 is deposited on belt 15 as it moves from the tail roll 11 to the head roll 12. As the ply passes over low vacuum box 22, water is withdrawn from ply 1.

The paperboard manufacturing machine 30 (Figure 2) has a fibrous ply top holding unit 40, two fibrous ply forming apparatus 10 further identified as I and II, and a bottom pressure roll 50. Unit II is rotated 1800 about a vertical axis from I so that the belt on each unit rotates in an opposite direction with respect to the other belt.

The fibrous ply top holding unit 40 has a tail roll 41, a head roll 42, a foot roll 43 and a guide roll 44.

Each of the rolls has a smooth continuous surface.

Tail roll 41 is adjustably mounted in the same way as tail roll 11, and guide roll 44 is adjustably mounted similar to guide roll 14.

The top holding unit 40 has an endless belt 45 mounted on the rolls 41,42,43 and 44. This belt rotates in a direction opposite to the belt on unit I. A vacuum box 46 is located below the belt run extending from tail roll 41 to head roll 42 to dry the belt 45 after it is spray washed with water from spray 47.

Located behind the run of belt from head roll 42 to the foot roll 43 is a high vacuum box 48 which is so located as to be opposite the head roll 12 of unit I. A drip pan 48 is positioned below the unit.

From the above it will be seen that the top holding unit 40 is very similar to the ply forming unit 10 with the main difference being that the vacuum boxes 46 and 48 are smaller than those used in the unit 10.

Top holding unit 40, however, is not used to form a ply, and because it has a different function, no headbox 28 is associated with it. The function of the top holding unit 40 is to apply pressure to ply 1 formed on unit 1 and to dewaterthe ply by means of vacuum box 48.

After a ply 1 is deposited on belt 15 of unit I in Figure 2, it is carried by the belt between head roll 12 of unit I and belt 45 of top holding unit 40. This causes pressure to be applied to ply 1 and the pressure plus the vacuum box 48 cause the water in ply 1 to move to the right. When ply 1 is carried by belts 15 and 45 between foot roll 43 of top holding unit 40 and vacuum box 24 of unit I, the water is caused to move to the left. Equally important, the vacuum box 24 assures that the ply transfers to the fabric that is continuing instead of following the fabric which is pulling away. This important feature carries through all of the embodiments of the invention.

Ply 2 is formed by depositing fibrous material on belt 15 of unit II (Figure 2). After being partly dewatered by low-vacuum box 22, the belt carries the ply over head roll 12 into pressure contact with the ply on the belt of unit I. Movement around roll 12 of unit II causes slight variations in the relative movement of the plies, thus mechanically aiding the bond between the plies. The pressure, together with the high vacuum in box 24 of unit I causes the water in the now mated plies 1 and 2 to flow to the left. As the so-mated plies move downwardly they pass bet ween foot roll 13 of unit I and belt 15 of unit 11. The resulting pressure and the high vacuum in box 24 now cause the water in the mated plies to flow to the right, and the two plies to disengage from the fabric on unit I and to follow the fabric on unit II.

A felt blanket 60 rolls over carrier roll 61 (Figure 2), vacuum box 62 and then over bottom pressure roll 50. The two-ply paperboard so formed is pressed between bottom pressure roll 50 and the lower portion of high-vacuum box 24 causing water to flow to the right. The two-ply paperboard (Figure 3) is carried between felt 60 and belt 15 of unit II over support roll 63 at which location the paperboard is removed from belt 15 and supported entirely by felt 60. The paperboard is then further treated to complete the paperboard manufacturing process.

The paperboard manufacturing machine of Figure 2 has the top holding unit 40 and the two fibrous ply forming apparatus units 10, identified as I and li, vertically arranged. Specifically, it will be noted that all of the head rolls 42 and 12, and foot rolls 43 and 13, have their axes in a vertical line.

Figure 4 illustrates a further embodiment of paperboard manufacturing machine which is readily produced from the basic machine illustrated in Figure 2 by incorporating an additional fibrous ply forming apparatus 10 into the machine for each additional ply it is desired to add to the two-ply paperboard. The pressure roll 50 and associated rolls 61 and 63 supporting felt 60 are, in this case, placed at the bottom ofthe lowermost unit 10. Forathree-ply paperboard, only unit Ill would be added after unit II and the direction in which felt 60 moves to complete the machine would be reversed.

The specific machine shown in Figure 4 is for the production of an eight-ply paperboard built from the inside out as shown in Figures. Each of the units I to VIII is an identical unit 10 with the even numbered units II, IV, VI and VIII rotated 180"about a vertical axis to put their front faces opposite portions of the front faces of odd numbered units, l, Ill, V and VII.

Each pairof adjacent units II and 111,111 and IV, IV and V and soon in Figure 4 are so positioned with respect to each other as to function in the same way as the units I and II described in conjunction with Figure 2. Furthermore, all the head rolls and foot rolls of the units I to VIII, and of the top unit 40, have their axes positioned in a vertical line. Furthmore, the plies of the paperboard shown in Figure 5 pro duced by the machine of Figure 4 from the inside out. Unit I forms ply 1, unit II forms ply 2, unit Ill forms ply 3, unit IV forms ply 4 and so on.

In a machine as illustrated by Figure 4, the flow of water through the paperboard being formed reverses direction nine times and this greatly increases the interconnection of fibers at the ply boundaries, this improves the bonding between the plies and enables a strong multiply paperboardto be produced.

The amount of vacuum in low vacuum box 22 and in high vacuum box 24 will vary according to the fibrous material used to make the paperboard. For recycled material, a vacuum of 250 to 2500 Pa. would be suitableforthe low vacuum box and a vacuum of 50 to 80 kPa. for the high vacuum box is considered acceptable. However, other values may be more suitable if the fibrous matter is rayon or another synthetic fiber.

Claims (12)

1. Afibrous ply forming apparatus, which can be assembled with at least one additional essentially identical fibrous ply forming apparatus to form a multiply paperboard making machine, comprising: four parallel, horizontally-positioned spaced-apart rolls comprising a tail roll, a head roll, a foot roll and a guide roll.

a fibrous ply-forming endless fabric belt wound over the four rolls, a low-vacuum box beneath the run of the fabric belt extending from the tail roll to the head roll for dewatering a fibrous ply forming material deposited on the fabric run, and a high-vacuum box behind the run ofthefabric belt extending from the head roll to the foot roll.

2. A fibrous ply forming apparatus according to claim 1 in which the top or tail roll is lower than the top of head roll and the fabric belt run between these two rolls is inclined.

3. Afibrous ply forming apparatus according to claim 1 or 2 in which the head roll is located substantially vertically above the foot roll.

4. Afibrous ply forming apparatus according to any of claims 1 to 3 in which the guide roll is between the foot roll and the tail roll.

5. Afibrous ply forming apparatus according to any of claims 1 to 4 including a headbox positioned to deposit a fibrous ply-forming material on the fabric belt run between the tail roll and the head roll.

6. A fibrous ply forming apparatus according to any of claims 1 to 5 in which each of the rolls has a solid continuous surface.

7. Afibrous ply forming apparatus according to any of claims 1 to 6 which includes a plurality of such apparatus and a fibrous ply holding unit which comprises: four parallel horizontally-positioned spaced-apart rolls, with said rolls being a tail roll, head roll, foot roll and guide roll, an endless fabric belt wound over the four rolls, a vacuum box beneath a run of the fabric belt extending from the tail roll to the head roll, and a vacuum box behind a run of the fabric belt extending from the head roll to the foot roll; each such forming apparatus including a headbox positioned to deposit a fibrous ply-forming material on the run of the fabric belt between the tail toll and the head roll, the holding apparatus and the plurality of forming apparatus being positioned such that: (i) the first forrning apparatus is positioned to have its head roll opposite the vacuum box of the holding unit and behind the run of the fabric belt extending from the head roll to the foot roll ofthe holding unit; (ii) the foot roll ofthe holding unit is positioned opposite the upper portion of the high-vacuum box of the first forming apparatus; (iii) the head roll ofthe second forming apparatus is positioned opposite the lower portion of the high-vacuum box of the first forming apparatus;; (iv) the foot roll ofthefirstforming apparatus is positioned opposite the upper portion ofthe highvacuum box of the second forming apparatus; and (v) a bottom pressure roll is positioned opposite the lower portion of the high-vacuum box of the second forming apparatus.

8. Apparatus according to claim 7 which includes more than two such forming apparatus, positioned in a substantially vertical arrangement with the front face of every other apparatus fronting on and being on the same side of a line, the bottom pressure roll being positioned opposite the lower portion of the high vacuum box of the lowermost forming apparatus.

9. Apparatus according to claim 7 or 8 in which the bottom pressure roll supports a paperboard pick-up felt belt blanket.

10. A machine according to any of claims 7 to 9 in which the axes of the head rolls and foot rolls of the holding unit and of all the forming apparatus are positioned to be in or close to a vertical center line.

11 A method of manufacturing multiply paperboard, which comprises: consecutively forming a serios of separate paper plies on individual moving fabrics, mating a second formed paper ply to one side of a first formed paper ply, mating a third formed paper ply to the other side of the first formed paptrply, subsequently mating any additional, consecutivelyformed paper plies first to the second ply and then to the third ply and continuing such alternating side mating of any additional plies to be deposited, and as the second and each subsequent ply is mated to the board being manufactured, causing water in the newly added ply teflow from it to and out of the one or more plies constituting the partially formed paperboard.

12. A method according to claim 11 in which the flow path of thepaperboard being formed is in a substantially downwardly directed vertical path.