GB2304124A

GB2304124A - Corrugating:single facer:pressing material onto fluted roll

Info

Publication number: GB2304124A
Application number: GB9523020A
Authority: GB
Inventors: Eiichi Isowa
Original assignee: Isowa KK
Current assignee: Isowa KK
Priority date: 1995-08-11
Filing date: 1995-11-09
Publication date: 1997-03-12
Also published as: ES2125156B1; ITMI960747A0; ITMI960747A1; IT1283743B1; JPH0952298A; TW325439B; ES2125156A1; FR2737679A1; GB9523020D0; FR2737679B1; DE19546766A1

Description

1 SINGLE FACER IN CORRUGATOR

BACKGROUND OF THE INVENTION

Field of the Invention

2304124 This invention relates to an apparatus which achieves bonding of a corrugating medium with a liner by nipping them together at plural positions to form a single-faced corrugated board.

Description of the Related Art

In the apparatus for forming a single-faced corrugated board (hereinafter referred to as single facer), a first fluted roll and a second fluted roll each having wavy flutes formed on th circumference are rotatably supported between frames in a vertical relationship in such a way that they may engage with each other by their flutes, and a press roll is designed to be brought into press contact with the second fluted roll via a corrugating medium and a liner which are the webs of the single-faced corrugated board. Namely, the corrugating medium, which is fed between the first fluted roll and the second fluted roll, is allowed to have a predetermined corrugation (flutes) when it passes between these rolls. A starchy glue is applied to the crests of corrugation thus formed by a gluing roll provided in a gluing mechanism. Meanwhile, the liner being fed from the opposite side with respect to the corrugating medium via the press roll is pressed against the glued crests of the corrugating medium, between the press roll and the second fluted roll, to be pasted together and form a single-faced corrugated board.

The press roll employed in the conventional single facer is of a largediameter metallic roll which is normally urged toward the second fluted roll so as to apply a predetermined nip pressure to the corrugating medium glued at the crests and the liner passing between these rolls. Since flutes consisting of alternative repetition of crests and troughs are formed continuously at a predetermined pitch on the circumference of the second fluted roll, the distance between the rotation center of the second fluted roll 2 and that of the press roll shift slightly as the point of press contact of the second fluted roll shifts from the trough to the crest or vice versa. Thus, as the result that the rotation centers of these rolls make cyclic reciprocating motions to be closer or farther relative to each other as they rotate, great vibration and big noise are generated during formation of the single-faced corrugated board, causing the working environment in the plant to be worsened considerably. Besides, such relative periodical shift of the rotation centers of these rolls causes the crests of the second fluted roll to hit the surface of the press roll to apply impact periodically (so-called the hammering phenomenon). Accordingly, linear press marks corresponding to the pitch of the crests of the second fluted roll are formed crosswise on the surface of the liner in the thus formed single-faced corrugated board, disadvantageously.

As a countermeasure for the problems described above, it is proposed to use an endless belt in place of the metallic press roll so as to nip the corrugating medium and the liner in cooperation with the second fluted roll. More specifically, the endless belt is disposed adjacent to the second fluted roll to be able to run freely, and the corrugating medium and the liner passing between the second fluted roll and the endless belt are adapted to be nipped therebetween and pasted together by bringing the endless belt closer to the outer surface of the second fluted roll. Thus, the use of the endless belt can prevent generation of great vibration and big noise and also formation of press marks on the single-faced corrugated board.

In a single facer in which a corrugating medium and a liner are designed to be pasted together by an endless belt and the second fluted roll, the corrugating medium and liner are designed to be nipped between the endless belt and the second fluted roll by applying a predetermined tension to the endless belt. In this case, the crosswise (in the axial direction of the second fluted roll) tension of the endless belt tends to be weaker toward the center, and it is difficult to apply uniform tension over the entire width of the belt. In other words, the nip pressure to be applied to the crosswise center of the corrugating medium and liner is weak to prevent them from being securely bonded together at such portion, causing bonding failure, disadvantageously.

3 Meanwhile, it is important to apply an optimum nip pressure depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium and of the liner so as to ensure bonding between the corrugating medium and the liner. However, it is difficult to accurately adjust the nip pressure of the endless belt at each position, as described above, and thus good adhesion between the corrugating medium and the liner cannot be constantly achieved under the present circumstances. Further, it can be also pointed out that the endless belt meanders during running to cause bonding failure between the corrugating medium and the liner, leading to unstable productivity. Besides, the endless belt also involves a problem that it is worn out soon to increase the running cost.

When a metallic press roll is employed, hot steam is distributed through the inside of the roll to heat the roll gurface to a predetermined temperature and to apply sufficient heat to the bonding portions of the corrugating medium and liner nipped between the press roll and the second fluted roll, so that gelation of the starchy glue may be accelerated. Thus, adhesion between the corrugating medium and the liner can be ensured. Accordingly, when an endless belt is employed, it is difficult to apply sufficient heat to the bonding portions of the corrugating medium and liner at the portions where they are nipped between the belt and the secondfluted roll. Thus, it can be pointed out that bonding failure caused by insufficient heat quantity, particularly when a thick single-faced corrugated board is to be formed.

SUMMARY OF THE INVENTION

The present invention was proposed in view of the problems inherent in the prior art, as described above, and in order to solve them successfully, and it is an objective of this invention to provide a single facer which can reduce not only vibration or noises to be generated when a single-faced corrugated board is formed by pasting a corrugating medium with a liner but also press marks to be formed on the liner, and which can ensure bonding between the corrugating medium and the liner.

In order to solve the above-described problems and attain the intended object, A one aspect of this invention is to provide a single facer, containing a first fluted roll having wavy flutes formed on the circumference; a second fluted roll, also having wavy flutes formed on the circumference to be engageable with the flutes of the first fluted roll, for imparting a required corrugation to a corrugating medium to be passed between the two rolls; and a gluing mechanism for gluing crests of the thus corrugated corrugating medium, which achieves bonding of the corrugating medium at the glued crests with a liner to form a single-faced corrugated board; the single facer comprising: a first press roll which is located on the circumference of the second fluted roll at a position adjacent to the route of feeding the liner to be rotatable as the liner is fed and to be able to adjust nip pressure to be applied in cooperation with the second fluted roll, and which presses the corrugating medium fed along the circumference of the second fluted roll and the liner to be pasted therewith against the second fluted roll; and at least one application means, which is located on the circumference of the second fluted roll at a position adjacent to the route of feeding the liner and on the downstream side of the first press roll with respect to the direction of feeding the corrugating medium being fed along the circumference of the second fluted roll to be able to adjust nip pressure to be applied in cooperation with the second fluted roll and to press the corrugating medium fed along the circumference of the second fluted roll and the liner to be pasted therewith against the second fluted roll; wherein the nip pressure of the first press roll and that of the application means are designed to be adjusted depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium. and of the liner.

Another aspect of this invention is to provide a single facer, containing a first fluted roll having wavy flutes formed on the circumference; a second fluted roll (14), also having wavy flutes formed on the circumference to be engageable with the flutes of the first fluted roll, for imparting a required corrugation to a corrugating medium to be passed between the two rolls; and a gluing mechanism for gluing crests of the thus corrugated corrugating medium, which achieves bonding of the corrugating medium at the glued crests with a liner to form a singlefaced corrugated board; the single facer comprising:

a first press roll which is located on the circumference of the second fluted roll at a position adjacent to the route of feeding the liner to be rotatable as the liner is fed and to be able to adjust nip pressure to be applied in cooperation with the second fluted roll, and which presses the corrugating medium fed along the circumference of the second fluted roll and the liner to be pasted therewith against the second fluted roll; a second press roll, which is located on the circumference of the second fluted roll at a position adjacent to the route of feeding the liner and on the downstream side of the first press roll with respect to the direction of feeding the corrugating medium being fed along the circumference of the second fluted roll to be rotatable as the liner is fed and to be able to adjust nip pressure to be applied in cooperation with the second fluted roll, which presses the corrugating medium fed along the circumference of the second fluted roll and the liner to be pasted therewith against the second fluted roll; an application means, which is located on the circumference of the second fluted roll at a position adjacent to the route of feeding the liner and between the first press roll and the second press roll to be able to adjust nip pressure to be applied in cooperation with the second fluted roll and to press the corrugating medium fed along the circumference of the second fluted roll and the liner to be pasted therewith against the second fluted roll; wherein the nip pressure levels of the first press roll, second press roll and application means are designed to be adjusted depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium and of the liner.

BRIEF DESCRIPTION OF THE DRAWINGS

The features of this invention that are believed to be novel are set forth with particularity in the appended claims. The invention, together with the objects and advantages thereof, may best be understood by reference to the following description of the preferred embodiment taken in conjunction with the accompanying drawings in which:

Fig. I shows schematically a constitutional view of a single facer according to a first embodiment of the invention; 6 Fig. 2 shows an explanatory view of an eccentric mechanism of the press roll according to the first embodiment; Fig. 3 shows a schematic side view of an application mechanism according to the first embodiment; Fig. 4 shows a schematic front view of the application mechanism according to the first embodiment;; Fig. 5 shows in schematic side view a modification of the application mechanism; Fig. 6 shows in schematic front view another modification of the application mechanism; Fig. 7 shows schematically a constitutional view of a single facer according to a second embodiment of the invention; and Fig. 8 shows schematically a constitutional view of a single facer according to a third embodiment of the invention.

DETAILED DESCRIPT10N OF THE PREFERRED EMBODIMENTS The single facer according to this invention will now be described by way of preferred embodiments referring to the attached drawings.

(First embodiment) Fig. 1 shows schematically a constitutional view of a single facer according to a first embodiment of the invention. In the single facer, a first fluted roll 12 having wavy flutes formed on the circumference and a second fluted roll 14 also having flutes formed on the circumference are rotatably supported between a pair of frame main bodies 10 (only one frame is shown in Fig. 1) which are spaced from each other at a predetermined distance. The rotary shaft of the first fluted roll 12 locates diagonally below that of the second fluted roll 14, and the flutes of the first fluted roll 12 are designed to be 7 engageable with those of the second fluted roll 14 via a corrugating medium 16 (to be described later). Meanwhile, a gluing mechanism 22 consisting of a gluing roll 18 and a doctor roll 20 is disposed beside the first fluted roll 12 and diagonally below the second fluted roll 14. A corrugating medium 16 is fed from a web feeding source (not shown) assumed to locate on the right side in Fig. 1, via a plurality of guide rolls 24, to the engagement zone defined between the first fluted roll 12 and the second fluted roll 14 to be corrugated as required by passing the engagement zone. The thus corrugated corrugating medium 16 is glued at the crests by the gluing mechanism 22 and then diverted upward along the circumference of the second fluted roll 14. Meanwhile, a liner 26 is fed from another web feeding source (not shown) assumed to locate on the left side in Fig. 1 via a pair of roll-like preheaters 28, which are steam- heated, to the second fluted roll 14 to be pasted with the glued crests of the corrugating medium 16 and fed as such upward. The corrugating mediiim 16 is also designed to be heated by hot steam distributed from a supply source (not shown) into the guide roll 24.

The gluing mechanism 22 is housed in a substantially closed pressure chamber 32 which is opening toward the first fluted roll 12 and the second fluted roll 14, and which is sealed between the opening and a first press roll 34 (to be described later) locating diagonally above the first fluted roll 12 and second fluted roll 14. Compressed air is supplied into this pressure chamber 32 from a supply source (not shown) so that the internal pressure of the pressure chamber 32 may be slightly higher (e.g. by 0. 15 atm.) than the atmospheric pressure. Circumferential grooves (not shown) are defined on the surface of the second fluted roll 14, so that the outer surface of the roll 14 facing the pressure chamber 32 may assume the atmospheric pressure. Accordingly, the corrugating medium 16 corrugated by passing between the first and second fluted rolls 12,14 is stably fed as pressed against the roll surface by the difference between the internal pressure of the pressure chamber 32 and the pressure on the outer surface of the second fluted roll 14. The corrugating medium 16 diverted upward along the outer surface of the second fluted roll 14 is then securely pasted with the liner 26 by two press rolls 34,36 (to be described later) and pressing members 38.

A pair of supporting frames 40 (only one frame is shown in Fig. 1) are 8 provided in the frame main bodies 10 locating above the second fluted roll 14. These supporting frames 40 are designed to be adjustable vertically by hydraulic cylinders (not shown), respectively. Two press rolls 34,36 for pasting the corrugating medium 16 with the liner 26 in cooperation with the second fluted roll 14 are disposed between the supporting frames 40 to be spaced from each other in the circumferential direction of the second fluted roll 14. Specifically, as shown in Fig. 1, a first press roll 34 is rotatably supported between the supporting frames 40 to be in contact with the circumference of the second fluted roll 14 adjacent to and on the left side of the route of feeding the liner 26, so that the corrugating medium 16 fed along the circumference of the second fluted roll 14 and the liner 26 to be pasted therewith may be pressed against the second fluted roll 14. Meanwhile, a second press roll 36 serving as an application means 15 rotatably supported between the supporting frames 40 to be in contact with the circumference of the second fluted roll 14 adjacent---toand on the right side of the route of feeding the liner 26, so that the corrugating medium 16 being fed along the circumference of the second fluted roll 14 and the liner 26 to be pasted therewith may be also pressed against the second fluted roll 14. More specifically, the liner 26 passed the preheaters 28 is first fed along the circumference of the first press roll 34 to the bonding zone where it is pasted with the corrugating medium 16. It should be noted here that the supporting frames 40 are designed to be shifted by the hydraulic cylinders between an operational position close to the second roll 14 and a retracted position spaced from the roll 14. At the operational position, the corrugating medium 16 is pasted with the liner 26 between these press rolls 34,36 and the second fluted roll 14; whereas at the retracted position, web passing, maintenance, etc. can be carried out.

These press rolls 34,36 are connected to a hot steam supply source (not shown) to allow hot steam to be distributed through the roll and heat the roll surface to a predetermined temperature. The liner 26 brought into contact with the press rolls 34,36 is thus heated to apply heat to the bonding portions of the corrugating medium 16 and the liner 26 and accelerate gelation of the starchy glue to ensure bonding between the corrugating medium 16 and the liner 26. These press rolls 34,36 are designed to be shiftable toward and away from the second fluted roll 14 by independent eccentric mechanisms 42, 9 respectively, to provide optimum nip pressure depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium 16 and of the liner 26.

As the eccentric mechanisms 42, for example, one shown in Fig. 2 may be employed, and the eccentric mechanism 42 disposed to the second press roll 36 will be described. Specifically, the rotary shaft 36a of the second press roll 36 is fitted to be rotatable in a through hole 44a of a race 44 rotatably supported on the corresponding supporting frame 40 via a bearing 46. The race 44 has a sectorial gear 44b integrally formed on the circumference, and the center Pi (axis of the rotary shaft 36a of the second press roll 36) of the through hole 44a is designed to be offset by a predetermined stroke x from the center P2 with respect to the circumference of the race. The sectorial gear 44b meshes with a pinion gear 48 rotatably supported on the supporting frame 40, and this pinion gear 48 is connected to a motor 50 disposed on the supporting frame 40 to be turned by the motor 50 as required. More specifically, when the motor 50 is driven to rotate the pinion gear 48, the sectorial gear 44b is turned together with the race 44. In this turning, since the center P2 with respect to the circumference of the race 44 is offset by the predetermined stroke x from the center Pi of the through hole 44a, the second press roll 36 is offset with the turning of the race 44. Thus, the axis-to-axis distance between the second press roll 36 and the second fluted roU 14 can be changed to adjust the nip pressure between these rolls 36,14. Incidentally, the eccentric mechanisms 42 are disposed on each aidal end of the second press roll 36 to shift the second press roll 36 eccentrically under synchronous driving of the pair of motors 50.

An application means 52 is interposed between the first press roll 34 and the second press roll 36, which achieves bonding between the corrugating medium 16 and the liner 26 in cooperation with the second fluted roll 14. Pressing members 38 in this application mechanism 52 serve as an application means. Specifically, as shown in Fig. 3, a pair of first cylinders 54 are supported at the bottom on the frame main bodies 10 to be spaced in the axial direction of the second fluted roll 14, a supporting plate 56 is connected to the piston rods 54a of the air cylinders 54 to maintain the supporting plate 56 to be parallel to the axis of the second fluted roll 14. A plurality of second air cylinders 58 are disposed on the surface of the supporting plate 56 opposing the second fluted roll 14 at predetermined intervals in the longitudinal direction (in the axial direction of the second fluted roll 14), and the piston rod 58a of each air cylinder 58 directing toward the second fluted roll 14 carries a holding member 60. Each holding member 60 holds a pressing member 38 via a plurality of rods 62 inserted slidablY into the member 60 such that the pressing member 38 can be moved closer to or farther from the second fluted roll 14, with a compression spring 64 being interposed between each pressing member 38 and each holding member 60 to normally urge the pressing member 38 toward the second fluted roll 14. The surface of each pressing member 38 opposing the second fluted roll 14 is arcuated after the circumferential profile of the roll 14, as showninFig.4. The plurality of pressing members 38 arranged in the axial direction of the second fluted roll 14 are closely arranged with no clearance, as shown in Fig. 3, to press the corrugating medium 16 and liner 26 against the second fluted roll 14 over the entire width of the roll 14. It is recommended that each pressing member 38 is positioned such that its edges may be aligned with the circumferential grooves defined on the second fluted roll 14.

Operation of the first air cylinders 54 disposed respectively on the frame main bodies 10 is controlled to shift the supporting plate 56 between the operational position near the second fluted roll and the retracted position away from the roll 14. With the supporting plate 56 locating at the operational position, the corrugating medium 16 and the liner 26 are pasted together between the pressing members 38 and the secon4 fluted roll 14; whereas with the supporting plate 56 locating at the retracted position, web passing, maintenance, etc. are adapted to be carried out. Meanwhile, operation of the second air cylinders 58 disposed on the supporting plate 56 is controlled to move the pressing members 38, Via the holding members 60, between a pressing position near the second fluted roll 14 and a nonpressing position away from the second fluted roll 14. More specifically, when the second air cylinders 58 are operated to extend the piston rods 58a in the state where the supporting plate 56 is located at the operational position by the first air cylinders 54 to move the holding members 60 and the pressing members 38 to the pressing position, the pressing members 38 are pressed, 11 via the liner 26 and the corrugating medium 16, against the second fluted roll 14 under the resilience of the compression springs 64. The nip pressure between the pressing members 38 and the second fluted roll 14 can be adjusted by adjusting the extending strokes of the piston rods 58a of the second air cylinders 58. Incidentally, when an excess load happens to be applied to the pressing members 38 during formation of a single- faced corrugated board, the pressing members 38 retract from the second fluted roll 14 against the resilience of the compression springs 64 to prevent the application mechanism 52 from undergoing the excess load.

(Action of the first embodiment) Next, action of the single facer according to the first embodiment of the invention will be described. When a single-faced corrugated board is to be produced, the supporting frames 40 are moved to the operational position to allow the first press roll 34 and the second press roll 36 disposed on the frames 40 to press the corrugating medium 16 fed along the circumference of the second fluted roll 14 and the liner 26 to be pasted therewith against the surface of the second fluted roll 14. The first press roll 34 and the second press roll 36 are offset by the eccentric mechanism respectively to adjust the nip pressure to be applied in cooperation with the second fluted roll 14 depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium 16 and of the liner 26. Meanwhile, the first air cylinders 54 are operated to bring the supporting plate 56 to the operational position to allow the plurality of pressing members 38 arrange on the supporting plate 56 to press the corrugating medium 16 fed along the circumference of the second fluted roll 14 and the liner 26 to be pasted therewith against the surface of the second fluted roll 14. The second air cylinders 58 are then operated to move the holding members 60 and pressing members 38 to the pressing position to bring the pressing members 38 into press contact with the second fluted roll 14 with a predetermined nip pressure. Incidentally, the nip pressure of each pressing member 38 is set at an optimum level depending on the various conditions for production. Further, with respect to those pressing members 38 locating in the region where the corrugating medium 16 and liner 26 do not run, the corresponding second air cylinders 58 remain 12 unoperated and are retained at the nonpressing position.

It has been proved by experiments and the like that bonding between the corrugating medium 16 and the liner 26 can be ensured by basically subjecting them to an initial bonding by applying first a high pressure, followed by application of a low nip pressure to achieve complete bonding. Accordingly, the levels of nip pressure to be applied by the first press roll 34, second press roll 36 and each pressing member 38 to the corrugating medium 16 and liner 26 may be smaller from the upstream end toward the downstream end with respect to the direction of feeding the corrugating medium 16. That is, the levels of nip pressure (NP) satisfy the following relationship: NP of first press roll 34 > NP of pressing members 38 > NP of second press roll 36.

The corrugating medium 16 fed from the web feeding source through the guide rolls 24 to the engagement zone defined between the first fluted roll 12 and the second fluted roll 14 under rotation of the first and second rolls 12,14 is corrugated as required when it passes through the zone. The thus corrugated corrugating medium 16 is glued at the crests of corrugation by the gluing mechanism 22 and then diverted upward along the circumference of the second fluted roll 14 (see Fig. 1).

Meanwhile, the liner 26 supplied from the web feeding source through the preheaters 28 is fed to the bonding zone defined between the second fluted roll 14 and the first press roll 34. The liner 26 is pressed against the crests of the corrugating medium 16 as nipped between the first press roll 34 and the second fluted roll 14 to undergo initial bonding. The corrugating medium 16 and the liner 26 underwent the initial bonding as nipped between the second fluted roll 14 and the first press roll 34 is then fed to the bonding zone defined between the second fluted roll 14 and the pressing members 38, where the corrugating medium 16 and the liner 26 are further pressed to be adhered. The corrugating medium 16 and the liner 26 are further fed to the bonding zone defined between the second fluted roll 14 and the second press roll 36, where they are fully adhered to provide a singlefaced corrugated board.

13 If the conditions for production including speed of feeding the corrugating medium 16 and the liner 26, as well as, kind, material, thickness, etc. thereof are changed in accordance with an order change and the like, the nip pressure of the first press roll 34, that of the second press roll 36 and those of the pressing members 38 are adjusted respectively depending on the conditions, and then production of a singlefaced corrugated board is started according to the new order. In this case, the levels of nip pressure (NP) are basically set as follows. NP of first press roll 34 > NP of pressing members 38 > NP of second press roll 36. Since the nip pressure of the first press roll 34, that of the second

press roll 36 and those of the pressing members 38 are designed to be adjustable in the first embodiment, optimum nip pressures can be provided depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium 16 and of the liner 26, constantly ensuring bonding between the corrugating medium 16 and the liner 26. Further, since the levels of nip pressure to be applied by the press rolls 34 and 36 and those of the pressing members 38 can be set lower compared with the case where one press roll is employed like in the prior art single facer, not only the vibration and noises to be generated during the formation of a singled-faced corrugated board but also press marks to be formed on the liner of the single-faced corrugated board can be notably reduced.

(Modification of the means for ascending and descending the supporting plate in the application mechanism), Figs. 5 and 6 show an ascending and descending means for the supporting plate 56 to be used in place of the first air cylinders 54 in the application mechanism 52. Specifically, a pair of gear boxes 66 are disposed on the opposing inner surfaces of the frame main bodies 10, respectively, and a horizontal ascending and descending shaft 68 is rotatably extended across these gear boxes 66. A bracket 70 is fixed to one frame main body 10 above the gear box 66, and a motor 72 is secured on the lower surface of the bracket 70. A gear 74 is attached to the output shaft of the motor 72 and is meshed 14 with a gear 76 attached to the ascending and descending shaft 68. A vertical ball screw 78 is rotatably supported in each gear box 66, and a bevel gear 80 attached to one end of the ball screw 78 is meshed with a bevel gear 82 attached to the end of the ascending and descending shaft 68 locating within the gear box 66. The lower portion of each ball screw 78 extended below the gear box 66 is screwed into a nut (not shown) provided on the supporting plate 56 disposed parallel to the axis of the second fluted roll 14. Accordingly, when the motor 72 is driven to rotate the ascending and descending shaft 68 in the positive or negative direction, the supporting plate 56 is moved parallelwise closer to or farther from the second fluted roll 14 under the cooperative action of the ball screws 78 and the nuts.

(Second embodiment) Fig. 7 shows schematically a conAtitutional view of a single facer according to a second embodiment of the invention. What is different from the first embodiment is that a third press roll is employed as the application means. Specifically, a third press roll 84, which is rotatably supported between supporting frames 40, is interposed between a first press roll 34 and a second press roll 36. The nip pressure of the third press roll 84 with respect to the second fluted roll 14 is designed to be adjustable by the eccentric mechanisms 42 described above. In this second embodiment, ensured bonding between the corrugating medium 16 and the liner 26 can be constantly achieved by adjusting the levels of nip pressure to be applied by these three press rolls 34,36,84 depending on the various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium 16 and of the liner 2G. The third press roll 84 is connected to a hot steam supply source (not shown) to allow hot steam to be distributed within the roll 84, so that the roll surface may be heated to a predetermined temperature. The liner 26 contacted with the third press roll 84 is heated to apply heat to the bonding portions of the corrugating medium 16 and liner 26, and thus gelation of the starchy glue is accelerated to ensure bonding between the corrugating medium 16 and the liner 26.

(Third embodiment) Fig. 8 shows schematically a constitutional view of a single facer according to a third embodiment of the invention. What is different from the first embodiment is the positional relationship of the fluted rolls 12,14. Specifically, a second fluted roll 14 is rotatably supported diagonally below a first fluted roll 12 rotatably supported between frame main bodies 10, wavy flutes of the former roll are designed to be engaged with those of the latter roll via a corrugating medium 16. A gluing mechanism 22 housed in a pressure chamber 32 is located immediately below the first fluted roll 12 and diagonally below the second fluted roll. The corrugating medium 16 is fed from a web feeding source (not shown) assumed to locate on the left side in Fig. 8 through a plurality of guide rolls 24 to the engagement zone defined between the first fluted roll 12 and the second fluted roll 14 to be corrugated as required by passing through the zone. The thus corrugated corrugating medium 16 is glued at the crests by the gluing mechanism 22 and then diverted upward along the circumference of the second fluted roll 14. Meanwhile, a liner 26 is fed from a web feeding source (not shown) assumed to locate on the right side in Fig. 8 via a plurality of preheaters 28 to the second fluted roll 14 to be pasted with the glued crests of the corrugating medium 16 and fed as such upward. Incidentally, the pressure chamber 32 in the third embodiment is designed to be sealed between the first fluted roll 12 and a seal roll 30 located immediately below the second fluted roll 14.

A pair of press rolls 34,36 and pressing means 38, which cooperate with the second fluted roll 14 to achieve bonding between the corrugating medium 16 and the liner 26 are disposed to be spaced from one another in the circumferential direction of the second fluted roll 14, at the positions across the second fluted roll 14 from the first fluted roll 12, respectively. Specifically, as shown in Fig. 8, a first press roll 34 is rotatablY located to be in contact with the circumference of the second fluted roll 14 and at a lower position adjacent to the route of feeding the liner 26, so that the corrugating medium 16 fed along the circumference of the second fluted roll 14 and the liner 26 to be pasted therewith may be pressed against the second fluted roll 14. Meanwhile, a second press roll 36 is rotatably supported to be in contact with the circumference of the second fluted roll 14 and at an upper position adjacent to the route of feeding the liner 26, so that the corrugating medium n 16 fed along the circumference of the second fluted roll 14 and the liner 26 to 16 be pasted therewith may be also pressed against the second fluted roll 14. More specifically, the first press roll 34 and the second press roll 36 are arranged in the vertical relationship to be in contact with the circumference of the second fluted roll 14 and adjacent to the route of feeding the liner 26. The liner 26 fed through the preheaters 28 is first fed along the circumference of the first press roll 34 to the bonding zone where it is pasted with the corrugating medium 16.

The nip pressure of the first press roll 34 and that of the second press roll 36 with respect to the second fluted roll 14 are designed to be adjustable by the same eccentric mechanisms 42 as described in the first embodiment. Incidentally, the first press roll 34 is designed to be abutted against the seal roll 34 so that the pressure chamber 32 can be maintained closed.

The application mechanism 52 i interposed between the press rolls 34,36, so that the corrugating medium 16 fed along the circumference of the second fluted roll 14 and the liner 26 to be pasted therewith may be pressed against the second fluted roll 14 by the pressing members 38 of the application mechanism 52. The nip pressure of each pressing member 38 with respect to the second fluted roll 14 is adapted to be adjustable by operating the corresponding second air cylinder 58.

More specifically, in the third embodiment, a single-faced corrugated board can be produced after the nip pressure levels of the two press rolls 34,36 and those of the pressing members 38 are adjusted depending on various conditions for production including the feeding speed, kind, material, thickness, etc- of the corrugating medium 16 and of the liner 26. Accordingly, not only ensured bonding between the corrugating medium 16 and the liner 26 can be constantly achieved, but also vibration and noises to be generated during the production, as well as, press marks to be formed on the liner of the single-faced corrugated board can be reduced.

In the third embodiment shown in Fig. 8, a third press roll may be employed as the application means.

(Variation) 17 While eccentric mechanisms are employed as the means for adjusting the nip pressure of the press rolls in any of the foregoing embodiments described above, the present invention is not limited to such constitution, but other mechanisms such as hydraulic cylinders, screw shafts, etc. can be also employed. Meanwhile, the levels of nip pressure to be applied by the first press roll, second press roll and application means to the corrugating medium and liner are basically set such that they may be gradually lower from the upstream end to the downstream end. However, these pressure levels can be set at random as required depending on various conditions for production. For example, these nip pressure levels may be higher from the upstream end to the downstream end or may be all the same, or the nip pressure of one member may be set at a high or low level. Further, the means for nipping the corrugating medium and liner in cooperation with the second fluted roll may consist of th-e first press roll and the second press roll only or of the first press roll and the application means only. Incidentally, as the means for retaining the corrugating medium on the circumference of the second fluted roll, it is also possible to employ a constitution in which the corrugating medium is sucked onto the circumference of the second fluted roll via through holes defined in the circumferential grooves of the roll by allowing the second fluted roll to assume a negative internal pressure.

is

Claims

What is Claimed is:

1. A single facer, containing a first fluted roll (12) having wavy flutes formed on the circumference; a second fluted roll (14), also having wavy flutes formed on the circumference to be engageable with the flutes of said first fluted roll (12), for imparting a required corrugation to a corrugating medium (16) to be passed between said two rolls (12,14); and a gluing mechanism (22) for gluing crests of the thus corrugated corrugating medium (16), which achieves bonding of said corrugating medium (16) at the glued crests with a liner (26) to form a single-faced corrugated board; said single facer comprising: a first press roll (34) which is located on the circumference of said second fluted roll (14) at a position adjacent to the route of feeding said liner (26) to be rotatable as said liner (26) is fed and to be able to adjust nip pressure to be applied in cooperation with said second fluted roll (14), and which presses said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner (26) to be pasted therewith against said second fluted roll (14); and at least one application means (36,38,84), which is located on the circumference of said second fluted roll (14) at a position adjacent to the route of feeding said liner (26) and on the downstream side of said first press roll (34) with respect to the direction of feeding said corrugating medium (16) being fed along the circumference of said second fluted roll (14) to be able to adjust nip pressure to be applied in cooperation with said second fluted roll (14) and to press said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner (26) to be pasted therewith against said second fluted roll (14); wherein the nip pressure of said first press roll (34) and that of said application means (36,38,84) are designed to be adjusted depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium (16) and of the liner (26).

2. A single facer, containing a first fluted roll (12) having wavy flutes formed on the circumference; a second fluted roll (14), also having wavy flutes formed on the circumference to be engageable with the flutes of said first fluted roll (12), for imparting a required corrugation to a corrugating 19 medium (16) to be passed between said two rolls (12,14); and a gluing mechanism (22) for gluing crests of the thus corrugated corrugating medium (16), which achieves bonding of said corrugating medium (16) at the glued crests with a hner (26) to form a single-faced corrugated board; said single facer comprising: a first press roll (34) which is located on the circumference of said second fluted roll (14) at a position adjacent to the route of feeding said liner (26) to be rotatable as said liner (26) is fed and to be able to adjust nip pressure to be applied in cooperation with said second fluted roll (14), and which presses said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner (26) to be pasted therewith against said second fluted roll (14); a second press roll (36), which is located on the circumference of said second fluted roll (14) at a position adjacent to the route of feeding said liner (26) and on the downstream siM -of said first press roll (34) with respect to the direction of feeding said corrugating medium (16) being fed along the circumference of said second fluted roll (14) to be rotatable as said liner (26) is fed and to be able to adjust nip pressure to be applied in cooperation with said second fluted roll (14), which presses said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner (26) to be pasted therewith against said second fluted roll (14); an application means (38,84), which is located on the circumference of said second fluted roll (14) at a position adjacent to the route of feeding said liner (26) and between said first press roll (34) and said second press roll (36) to be able to adjust nip pressure to be applied in cooperation with said second fluted roll (14) and to press said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner (26) to be pasted therewith against said second fluted roll (14); wherein the nip pressure levels of said first press roll (34), second press roll (36) and application means (38,84) are designed to be adjusted depending on various conditions for production including the feeding speed, kind, material, thickness, etc. of the corrugating medium (16) and of the liner (26).

3. The single facer according to Claim 2, wherein the nip pressure of said first press roll (34), that of said second press roll (36) and that of said application means (38,84) are set according to a predetermined pattern.

4. The single facer according to Claim 2, wherein the nip pressure to be applied by said first press roll (34), that of said second press roll (36) and that of said application means (38,84) to said corrugating medium (16) and said liner (26) are designed to be smaller gradually from the upstream end to the downstream end with respect to the direction of feeding said corrugating medium (16).

5. The single facer according to any of Claims 1, 2, 3 and 4, wherein said application means consists of pressiaig members (38) which can be brought into slide contact with said liner (26) and which is designed to press said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner to be pasted therewith against said second fluted roll.

6. The single facer according to any of Claims 1, 2, 3 and 4, wherein said application means is a third press roll (84) which rotates as said liner (26) is fed, and which is designed to press said corrugating medium (16) fed along the circumference of said second fluted roll (14) and said liner (26) to be pasted therewith against said second fluted roll (14).

7. A single facer substantially as hereinbefore described with reference to the accompanying drawings.