Load-applying device for a double facer

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a load-applying device for a double facer of a corrugator that manufactures corrugated board sheets.

2. Prior Art

In corrugated board sheets, a liner and a core paper are fed out on the upstream side of a corrugator, and after the core paper has been corrugated with a desired flute by a single facer, the core paper is pasted to the liner, thus manufacturing a continuous single-faced corrugated board sheet. Then, as shown in

FIG. 19

, the single-faced corrugated board sheet and a back liner are pasted together in a double facer

1

. Thus, a continuous corrugated board sheet S is formed. Afterward, this sheet is cut and trimmed to desired dimensions by a slitter-scorer and/or cutter (not shown), stacked by a stacker, etc. and then sent to a box-making process or shipping.

As seen from

FIG. 19

, the double facer

1

is comprised of two sections: a heating section

2

and a cooling section

3

.

An upper conveyor belt

4

and a lower conveyor belt

5

which hold and convey the corrugated board sheet S passing through the double facer

1

are provided so as to introduce a single-faced corrugated board sheet conveyed from the upstream side and a liner into the double facer

1

, cause the sheet and liner to pass through the double facer

1

, and then convey the sheet and liner to a slitter-scorer or cutter (not shown) of a downstream process.

The upper conveyor belt

4

is mounted on a driving roll

6

, an introduction roll

7

and tension rolls

8

a

and

8

b

. The driving roll

6

is disposed above the running corrugated board sheet S on the downstream side of the double facer

1

. The introduction roll

7

is disposed on the upstream side of the double facer

1

. The tension rolls

8

a

and

8

b

are disposed above the double facer

1

at intermediate points in the conveying direction. The upper conveyor belt

4

is driven by the driving roll

6

.

The lower conveyor belt

5

is mounted on a driving roll

9

, an introduction roll

10

and a tension roll

11

. The driving roll

9

is disposed beneath the running corrugated board sheet S on the downstream side of the double facer

1

. The introduction roll

10

is disposed on the upstream side of the cooling section

3

at an intermediate point in the conveying direction of the double facer

1

. The tension roll

11

is disposed beneath the double facer

1

at an intermediate point (with respect to the conveying direction) between the introduction roll

10

and the driving roll

9

. The lower conveyor belt

5

is driven by the driving roll

9

.

The upper conveyor belt

4

and the lower conveyor belt

5

are controlled by a driving device (not shown) and a control device (not shown) which controls the driving device, so that the driving rolls

6

and

9

rotate in synchronization with each other.

In the heating section

2

of the double facer

1

, a pressing device

12

is disposed above the corrugated board sheet S. Also, a heating device

15

is disposed beneath the corrugated board sheet S.

The pressing device

12

includes a means in which a plurality of weight rolls are disposed in the sheet conveying direction, and pressure is applied to the running corrugated board sheet S via the upper conveyor belt

4

by the weight of the weight rolls. The pressing device

12

further includes a means such as that shown in FIG.

19

. In this pressing means, a plurality of devices, in which a plate

14

is driven by a driving member

13

so that pressure is applied to the corrugated board sheet S via the upper conveyor belt

4

, are disposed in the sheet conveying direction, and the running corrugated board sheet S is pressed by the pressing force of these pressing devices via the upper conveyor belt

4

.

Numerous patent applications have been filed on such pressing means, etc. including, for instance, Japanese Patent Application Laid-Open (Kokai) Nos. 6-328596, 8-109590, and 2000-62055.

In the heating device

15

, a plurality of heating plates which are heated by high-temperature steam or heating plates which cause induction heating of the corrugated board sheet by means of induction heating devices, etc., are disposed in the sheet conveying direction. In addition, the single-faced corrugated board sheet and liner that are conveyed from the upstream side are heated by the heating members

16

of the heating device

15

so that the glue is gelled and bonding occurs.

The corrugated board sheet S is formed as a result of the bonding of the single-faced corrugated board sheet and liner by the action of the pressing device

12

and heating device

15

. Then, when the corrugated board sheet S has passed through the heating section

2

, the sheet S enters the cooling section

3

.

In the cooling section

3

of the double facer

1

, a plurality of weight rolls

18

of a load-applying device

17

are disposed above the corrugated board sheet S in the sheet conveying direction, and the cooling section

3

is constructed so that the weights of the respective weight rolls

18

are applied to the corrugated board sheet S via the upper conveyor belt

4

. A conveying supporting device

19

is comprised of a plurality of conveying rolls

20

. The conveying rolls

20

are disposed in the sheet conveying direction beneath the corrugated board sheet S and support the corrugated board sheet S from below.

The heated corrugated board sheet S conveyed from the heating section

2

is held and conveyed by the upper conveyor belt

4

and lower conveyor belt

5

. While the corrugated board sheet S passes through the cooling section

3

, the corrugated board sheet S is pressed by the weight rolls

18

while being supported by the weight rolls

18

and conveying rolls

20

. The final bonding is thus accomplished, and the heated corrugated board sheet S is cooled.

In the load-applying device

17

of the cooling section

3

, instead of the weight rolls

18

, a means that presses the corrugated board sheet S via the upper conveyor belt

4

using the pressing device disclosed in the above-described Japanese Patent Application Laid-Open (Kokai) No. 6-328596 may be used.

When the corrugated board sheet S has passed through the cooling section

3

, the corrugated board sheet S leaves the double facer

1

. The corrugated board sheet S is conveyed to a slitter-scorer or cutter (not shown) of a downstream process, and then the sheet is cut and trimmed to a desired size.

In a conventional double facer, the corrugated board sheet S is pressed by weight rolls from above. However, the weight rolls are rotatably shaft-supported on side frames (not shown) of the double facer

1

. They are individually adjusted so that the rolls are parallel with respect to the direction of width of the machine, and so that the height between the respective weight rolls is also uniform. Furthermore, the side frames are raised and lowered in accordance with the flute of the corrugated board sheet S that is to be produced. Accordingly, the weight rolls are raised and lowered in accordance with the raising and lowering movements of the side frames, so that the corrugated board sheet S is pressed.

However, the problem is that in regard to the work of attaching these weight rolls to the side frames of the double facer, time and effort are required for assembly. Also the adjustments that are made require experience and are not easily accomplished. Thus, the adjustment work is a burden on the assembly workers.

Furthermore, in recent corrugators, there has been a progressive increase in the size and speed of the machinery, and double facers also have a machine width of 2500 mm to 2800 mm. In addition, high-speed corrugators in which the speed ranges from 350 meters per minute to 400 meters per minute have also appeared. Accordingly, in order to heat-bond and cool the corrugated board sheet by means of a double facer, the double facer itself must be constructed with a long machine length.

When the machine length and machine width of the double facer are thus increased, adjustment of the weight rolls on an individual basis in the sheet conveying direction becomes difficult, and parallel alignment also becomes difficult in mechanical terms. Also, as the length of the machine increases, the height adjustment of the weight rolls, several tens of which may be lined up in the sheet conveying direction, becomes difficult.

As a result of the factors above, it becomes extremely difficult to apply a uniform load to the corrugated board sheet S using weight rolls alone. Accordingly, the raising-and-lowering device must be used to align the weight rolls with the height of the flute of the corrugated board sheet produced, and a load must be applied by adjusting the raising-and-lowering device so that a sufficient load is applied to the corrugated board sheet S.

Since a plurality of weight rolls lined up in the sheet conveying direction show height differences with respect to the corrugated board sheet, weight rolls that apply an excessive load to the corrugated board sheet will crush the corrugated board sheet. Conversely, weight rolls that apply no load to the corrugated board sheet at all cannot apply a sufficient bonding action, resulting in bonding defects occurring in the corrugated board sheet.

Furthermore, since the weight rolls and corrugated board sheet make linear contact in the direction of width, a concentrated load is applied each time that the corrugated board sheet passed directly beneath a weight roll.

In addition, since the core paper of the corrugated board sheet is corrugated, the reaction force caused by the load of the weight rolls varies between the crests of the corrugations and the areas between the crests of the corrugations, so that the weight rolls vibrate in the vertical direction.

In a double facer, a plurality of weight rolls are disposed in the sheet conveying direction. Thus, the weight rolls vibrate in the vertical direction when the corrugated board sheet runs, so that the load of the weight rolls becomes greater than necessary. Also, since the contact is linear contact, the load of the weight rolls is applied to the corrugated board sheet as a linear pressure, thus causing crushing of the corrugations of the corrugated board sheet. Moreover, the weight rolls also show vibration caused by the vertical movement as described above, and noise that is generated by the vibration, etc. The working environment of the operator is thus not desirable.

In addition, in cases where the width of the corrugated board sheet is narrower than the width of the weight rolls, the entire weight of each weight roll is applied to the corrugated board sheet. This results in that crushing of the corrugations may occur when an excessive load is applied to the corrugated board sheet.

Furthermore, another problem that is different from the weight rolls is warping of the corrugated board sheet.

More specifically, as a result of the progressively higher speeds of corrugators in recent years, the corrugated board sheet passes through the double facer at a high speed. In order to achieve reliable bonding of the corrugated board sheet passing through at a high speed, sufficient heating must be performed in the heating section of the double facer. However, as a result of the application of heat to the corrugated board sheet, the moisture contained in the corrugated board sheet evaporates. As a result of the evaporation of the moisture, warping occurs in the corrugated board sheet, thus causing a drop in product quality and resulting in the manufacture of a defective sheet.

In the case of weight rolls, these rolls make linear contact with the corrugated board sheet (although the contact is via the upper conveyor belt), and there are gaps between the weight rolls. The result is that the evaporation of moisture is unavoidable.

Thus, there are various problems in a system that applies a load to the corrugated board sheet by means of weight rolls.

On the other hand, in devices that use the pressing means as disclosed in Japanese Patent Application Laid-Open (Kokai) Nos. 6-328596, 8-109590 and 2000-62055, pressing is performed by means of a pressing force based on a structure that is mechanically adjusted beforehand. However, the structure is complicated, the number of parts required is large and the manufacturing cost is high. Furthermore, once trouble occurs, maintenance is difficult to perform.

Moreover, the pressing forces apply pressure by means of forces that are determined in design terms by mechanically constructed structural bodies and driving bodies such as springs, etc. Accordingly, for example, in cases where it is desired to alter the pressing force, the amount of compression of the springs must be changed by altering the setting of the gap between the pressing devices and the belt. In the case of driving bodies such as springs, for example, the springs must be replaced with springs that have a different spring constant.

However, in order to alter the setting of the gap between the pressing devices and the belt, it is necessary to make the heights of all of the pressing devices uniform using a dimension gauge, etc. This adjustment work requires time and is extremely difficult to perform during ordinary operations. Furthermore, the replacement of even a single spring requires the calculation of the pressing force in the pressing device that accompanies the spring constant of the spring. Moreover, replacement of the pressing device to which the spring is attached, and adjustment work following the replacement, are required. Thus, this work cannot be easily performed by the operator, making it necessary for the replacement to be performed by a designer or worker who has special knowledge, such as a machine maker, etc.

As seen from the above, there have been various problems in systems that apply a load to the corrugated board sheet using pressing means. Furthermore, in a double facer, these problems are common to both the heating section and the cooling section.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to reduce manufacturing costs of corrugated board sheet by means of a simple structure in which maintenance can easily be performed.

Another object of the present invention is to produce a corrugated board sheet with stable quality by way of preventing crushing of the corrugated board sheet caused by a load that is greater than necessary and preventing faulty bonding caused by the failure to apply a load.

A further object of the present invention is to produce a corrugated board sheet with stable quality by way of inhibiting the evaporation of the moisture content and reducing the generation of warping.

The above objects are accomplished by a unique structure for a load-applying device used in a double facer that comprises:

a heating section into which a single-faced corrugated board sheet and a liner sheet are supplied, and glue applied as a coating to the crests of the corrugations of the single-faced corrugated board sheet is hardened so that the single-faced corrugated board sheet and liner sheet are bonded together, and

a cooling section which cools the corrugated board sheet and said liner sheet bonded together in the heating section, wherein the load-applying device is comprised of:

a surface pressure applying body which is disposed above the corrugated board sheet so as to face the corrugated board sheet and which applies a surface pressure to the corrugated board sheet,

weight blocks which are carried on top of the surface pressure applying body, and

load bodies in which one end of the surface pressure applying body is fastened to the double facer, while the other end is caused to ride on the corrugated board sheet in the sheet conveying direction, and wherein

a plurality of the load bodies are disposed at right angles with reference to the sheet conveying direction.

The above objects are accomplished by another unique structure of the present invention for a load-applying device used in a double facer that comprises:

a heating section into which a single-faced corrugated board sheet and a liner sheet are supplied, and glue applied as a coating to the corrugation crests of the corrugations of the single-faced corrugated board sheet is hardened so that the single-faced corrugated board sheet and liner sheet are bonded together, and

a cooling section which cools the corrugated board sheet bonded in the heating section, wherein

the load-applying device is comprised of:

a surface pressure applying body which has connecting sections on the upstream side and downstream side, the surface pressure applying body being disposed above the corrugated board sheet so as to face the corrugated board sheet and applying a surface pressure to the corrugated board sheet,

weight blocks which are carried on the surface pressure applying body, and

load bodies formed in the form of a chain in which a plurality of the surface pressure applying bodies are disposed in the sheet conveying direction and formed into the form of a chain by being connected at the connecting sections, one end of the surface pressure applying bodies formed into the form of chain being fastened to the double facer, while the other end of the surface pressure applying bodies formed into the form of a chain being caused to ride on the corrugated board sheet in the sheet conveying direction, and wherein

a plurality of the load bodies formed into the form of a chain are disposed at right angles with reference to the sheet conveying direction.

Furthermore, the above objects are accomplished by still another unique structure of the present invention for a load-applying device used in a double facer that comprises:

a heating section into which a single-faced corrugated board sheet and a liner sheet are supplied, and glue applied as a coating to the corrugation crests of the corrugations of the single-faced corrugated board sheet is hardened so that the single-faced corrugated board sheet and liner sheet are bonded together, and

a cooling section which cools the corrugated board sheet bonded in the heating section, wherein

the load-applying device is comprised of:

a surface pressure applying body which is disposed above the corrugated board sheet so as to face the corrugated board sheet, the surface pressure applying body covering the entire surface of the corrugated board sheet in the direction of width and applying a surface pressure to the corrugated board sheet, and

weight blocks which are carried on top of the surface pressure applying body, with two or more of these weight blocks being carried at right angles with reference to the sheet conveying direction, and wherein

one end of the surface pressure applying body is fastened to the double facer while the other end of the surface pressure applying body is caused to ride on the corrugated board sheet in the sheet conveying direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a side view of the load-applying device in accordance with one embodiment of the present invention, the load-applying device being used in the cooling section of a double facer;

FIG. 2

is a side view of the load-applying device and load bodies of the present invention;

FIG. 3

is a plan view of the load-applying device and load bodies of the present invention;

FIG. 4

is a side view of the fastening portion of the load bodies and stay of the present invention;

FIG. 5

is a side view of the connecting members of the load bodies;

FIG. 6

is a plan view of the side guides of the load bodies;

FIG. 7

is a perspective view of the load-applying device and load bodies of the present invention;

FIG. 8

is a plan view showing the relationship between the weight blocks and the corrugated board sheet in the perpendicular direction with reference to the sheet conveying direction;

FIG. 9

is a plan view of an embodiment of the present invention in which the weight blocks are disposed so as to be staggered between the load-applying devices in the sheet conveying direction;

FIG. 10

is a plan view of an embodiment of the present invention in which the load bodies are staggered;

FIG. 11

is a plan view of a load-applying device constructed according to another embodiment of the present invention;

FIG. 12

is a side view of the load bodies constructed according to another embodiment of the present invention;

FIG. 13

is a plan view of the load bodies constructed according to another embodiment of the present invention;

FIG. 14

is a side view of an embodiment of the present invention in which the load-applying device is used in the heating section of a double facer;

FIG. 15

is a side view of the load-applying device and load bodies shown in

FIG. 14

;

FIG. 16

is a plan view of a modification of the surface pressure applying body of the present invention;

FIG. 17

is a sectional view illustrating a modification of the surface pressure applying body of the present invention;

FIG. 18

is a plan view showing a state in which the weight blocks in a modification of the surface pressure applying body are disposed in a staggered configuration; and

FIG. 19

is a side view of a conventional double facer.

DETAILED DESCRIPTION OF THE INVENTION

Preferred embodiments of the load-applying device for a double facer of the present invention will be described with reference to the accompanying drawings.

FIG. 1

is a side view of an embodiment of the present invention in which the load-applying device is installed in a cooling section

3

of a double facer

1

. The structure of the double facer other than the load-applying device is substantially the same as that of a conventional double facer. Accordingly, a detailed description thereof is omitted.

In the cooling section

3

, load-applying devices

21

,

28

and

29

are disposed above the running corrugated board sheet S. It is generally desirable that the load-applying devices be disposed throughout the section in the sheet conveying direction; however, at least one device may be disposed as necessary.

In the embodiment shown in

FIG. 1

, three load-applying devices

21

,

28

and

29

are disposed in the sheet conveying direction. Since the three load-applying devices

21

,

28

and

29

shown in

FIG. 1

all have the same structure, the load-applying device

21

which is positioned in the furthest upstream portion of the cooling section

3

will be described in further detail below with reference to

FIGS. 2 through 10

.

In the load-applying device

21

, a stay

23

is provided on the frame

30

of the double facer

1

via a supporting member

31

(see

FIG. 3

for both); and one end of a surface pressure applying body

24

is fastened to the stay

23

by a fastening member

40

(see FIG.

4

), while the other end of the surface pressure applying body

24

is caused to ride on the upper conveyor belt

4

toward the downstream side of the double facer

1

. In this case, it is generally desirable that the other end of the surface pressure applying body

24

be left as a free end. However, the other end can be held by a stay on the downstream side either.

Weight blocks

27

are carried on one side of the face pressure applying body

24

which is caused to ride on the upper conveyor belt

4

with one end of the surface pressure applying body

24

being fastened to the stay

23

, such one side being an opposite side from the side of the surface pressure applying body

24

that contacts the upper conveyor belt

4

.

FIG. 2

shows the overall load-applying device

21

.

It is sufficient if the surface pressure applying body

24

has a length that allows at least one weight block

27

(described later) to be carried. However, in order to achieve the object of the present invention in a favorable manner, it is desirable to use a surface pressure applying body

24

that has a length that allows a plurality of weight blocks (two or more weight blocks) to be carried.

The surface pressure applying body

24

has a desired thickness. It is sufficient that the thickness allows the transmission of the weight of the weight blocks

27

to the corrugated board sheet S as a surface pressure. If the thickness of the surface pressure applying body

24

is too large, the fit with the running upper conveyor belt

4

is poor, and a desirable surface pressure based on the weight of the weight blocks

27

cannot be obtained.

Accordingly, it is desirable that the surface pressure applying body

24

has a thickness which is such that when the weight blocks

27

are placed on the surface pressure applying body

24

, the surface pressure applying body

24

receives the weight of the weight blocks

27

and applies a load to the corrugated board sheet S as a surface pressure while showing a good fit with the upper conveyor belt

4

.

As to the material of the surface pressure applying body

24

, a material, that reduces the frictional resistance with the upper conveyor belt

4

, is resistant to wear caused by friction, and has a good heat resistance, is generally desirable. The main materials used in this case include stainless steel sheets, steel sheets whose surfaces have been plated, hard resin type materials such as Teflon and nylon, etc., fiber type materials such as carbon and fibers, etc., and ceramic materials, etc.

Furthermore, it is also possible to execute a surface treatment, that reduces frictional resistance as in the canvas belt used for the upper conveyor belt

4

, on a belt and use such a belt as the surface pressure applying body

24

.

The surface pressure applying body

24

that carries the weight blocks

27

of the load body

22

is constructed so that it covers the entire surface of the corrugated board sheet S. Accordingly, there is little escape of moisture even when the corrugated board sheet S is heated by the heating device

15

, and thus warping of the corrugated board sheet S tends not to occur.

As is clear from

FIGS. 3 and 7

, the weight blocks

27

have a specified length, width and thickness.

Each weight block

27

has a weight that applies a load that is required in absolute terms in order to achieve secure bonding of the corrugated board sheet S that is to be produced. Generally, for example, in cases where a double flute in which the corrugated board sheet is formed from two layers is produced, the required weight is that the load is obtained when a specified number of weight blocks

27

are placed on the surface of the surface pressure applying body

24

so that the load of these weight blocks

27

is applied to the corrugated board sheet S.

In concrete terms, the weight of a single weight block is approximately 100 to 1000 grams.

Furthermore, as long as the above-described purpose is achieved, the weight blocks may be physical objects of any type of structure. The principal physical materials used may be metal substances such as iron, copper or aluminum, etc., resin type substances such as Teflon or nylon, etc., stone type substances obtained by hardening and firing clay, etc., and rubber type substances or ceramic type substances, etc. Plastic type boxes containing water, etc. are also conceivable. However, such plastic type boxes containing water, etc. may be expected to absorb heat from the surface of the heated corrugated board sheet S and radiate this heat upward, etc.

The weight blocks

27

may also be long weight blocks that have approximately the same length as the surface pressure applying body

24

.

Each of the weight blocks

27

has a structure which can be simply carried on the upper surface of the surface pressure applying body

24

. This is basically most desirable. However, the weight blocks

27

may also be positioned using an adhesive tape or glue, etc. so that the weight blocks will not fall off of the surface pressure applying body

24

.

In the shown embodiment, the weight blocks

27

are lined up in an orderly manner on the surface pressure applying body

24

. In order to prevent the weight blocks

27

from falling off of the surface pressure applying body

24

, frame-form casings

25

and

26

as shown in

FIGS. 2 through 7

are used. The frame-form casings

25

and

26

are slightly larger than the weight blocks

27

and installed in upright positions so as to surround and support the weight blocks

27

on at least three sides above the surface pressure applying body

24

. Such three sides include both side surfaces and the downstream side with respect to the sheet conveying direction. The weight blocks

27

are accommodated inside these casings

25

and

26

.

It is also possible to use frame-form casings that surround the weight blocks

27

on four sides thereof, so that the upstream sides of the weight blocks

27

in the sheet conveying direction are also supported.

It is further possible to install bottoms on the undersurfaces of the frame-form shapes, so that box-form bodies are formed. These box-form bodies are arranged so that the bottoms are carried on the upper surface of the surface pressure applying body

24

. Furthermore, though not shown, it is also possible to use a structural body in which a frame body is installed directly on the surface pressure applying body, so that the structural body has a casing function which allows the surface pressure applying body itself to accommodate the weight blocks.

Cut-outs

32

are formed in the casings

25

and

26

at specified intervals. Since the casings

25

and

26

are structural bodies that surround the weight blocks

27

on three or four sides, the cut-outs

32

are formed so that slack in the surface pressure applying body

24

can be absorbed by the cut-outs

32

.

More specifically, the surface pressure applying body

24

is a structural body with a thickness that allows an appropriate fit with the corrugated board sheet S and upper conveyor belt

4

. Thus, the slack occurs in the surface pressure applying body

24

when the surface pressure applying body is subjected to a force such as an upward push from the corrugated board sheet S or upper conveyor belt

4

, etc. Such a slack is absorbed by the cut-outs

32

formed in the casings

25

and

26

.

If the cut-outs

32

are disposed in accordance with the length of the weight blocks

27

, then the cut-outs

32

and the connecting joints between the weight blocks

27

will coincide. Accordingly, when slack develops in the surface pressure applying body

24

, the slack can be absorbed by the cut-outs

32

and connecting joints between the weight blocks

27

which are disposed in the same positions.

In the shown embodiment, two casings

25

and

26

are disposed on the upstream side and the downstream side of one surface pressure applying body

24

, and respective weight blocks

27

are carried inside each of the casings

25

and

26

.

Since the weight blocks

27

are merely carried on the surface pressure applying body

24

as described above, these weight blocks can be replaced with weight blocks

27

of a different weight if necessary. In other words, the weight blocks

27

can be replaced in accordance with various production conditions such as the flute that is produced, the paper material, the paper width and the production speed, etc.

Next, the arrangement of installation of the load-applying device

21

in the perpendicular direction or in the right-angle direction with reference to the sheet conveying direction will be described.

As is clear from

FIGS. 3 and 7

, a plurality of load bodies

22

in which weight blocks

27

are carried on surface pressure applying bodies

24

are lined up at right angles with reference to the sheet conveying direction shown by an arrow D, thus forming one load-applying device. The width of a single load body

22

is determined by the widths of the plurality of weight blocks

27

that are carried on the surface pressure body

24

in the direction perpendicular to the sheet conveying direction D (see

FIG. 3

) or in the direction of width of the machine. The size of the single load-applying device

21

in the direction of width of the machine is determined by the load-applying device structured by lining up the weight blocks

27

in the direction of width of the machine or in the perpendicular direction with reference to the sheet conveying direction.

The load-applying device

21

applies a load to the corrugated board sheet S from above with the upper conveyor belt

4

in between. Moreover, the load-applying device

21

is set so that both ends of the corrugated board sheet S are always pressed regardless of the paper width of the corrugated board sheet S that is being produced. In other words, the load-applying device is set so that the ends of the corrugated board sheet S are not positioned between adjacent load bodies

22

.

Generally, corrugated board sheets are produced using a paper width with a pitch of 50 mm. Accordingly, as shown in

FIG. 8

, a weight block

27

with a width of e.g. 75 mm is placed in the center L with respect to the direction of width W (see

FIG. 8

) of the machine as seen from FIG.

8

. Also, weight blocs

27

which all have a width of 50 mm are placed on both sides of the center weight block

27

. Thus, the ends of the corrugated board sheet that is being produced are not positioned between adjacent load bodies

22

.

More specifically, in

FIG. 8

, X indicates a weight block which has a width of 75 mm, and weight blocks with a width of 50 mm indicated by Y are placed on both sides of the weight block X. In this case, when a corrugated board sheet S with a paper width WI of 2000 mm is passed through and produced in

FIG. 8

, the distance of both ends of the corrugated board sheet S from the center L with respect to the direction of width W of the machine is 1000 mm. Accordingly, since both ends of the Yn-th weight blocks

27

are located at a distance of 1037.5 mm from the center L with respect to the direction of width of the machine, a difference of 37.5 mm is generated.

On the other hand, when a corrugated board sheet S with a paper width W2 is passed through and produced, both ends of the corrugated board sheet S are located at a distance of 975 mm from the center L with respect to the direction of width W of the machine; accordingly, both ends of the Yn−1-th weight blocks

27

are located at a distance of 987.5 mm from the center L with respect to the direction of width W of the machine. Thus, a difference of 12.5 mm is generated.

If the setting is made as described above, then in cases where a corrugated board sheet is produced using a paper width with a pitch of 50 mm, both ends of the corrugated board sheet S will always pass through within the widths of the weight blocks of the respective load bodies

22

in the sheet conveying direction. Thus, both end portions of the corrugated board sheet S will always be loaded by the load bodies

22

.

However, if the load bodies

22

are disposed with weight blocks

27

lined up in the same positions in the sheet conveying direction, unloaded regions in which no load at all is applied to the corrugated board sheet S while the corrugated board sheet

21

passes through the load-applying device

21

are generated between adjacent load bodies

22

. Thus, faulty bonding results.

In order to counter this, the load bodies

22

a

,

22

b

,

22

c

and so on are disposed so that the arrangement of the weight blocks

27

is staggered between the upstream side and the downstream side of one load-applying device

21

as shown in FIG.

10

.

More specifically, the load bodies

22

a

,

22

b

,

22

c

and so on which are on the downstream side are disposed so as to be shifted by one-half the dimension of one load body

22

in the direction of width of the sheet relative to the load bodies

22

a

,

22

b

,

22

c

and so on disposed on the upstream side. In the upstream-side load bodies and downstream-side load bodies, respective pins

37

and

38

are installed on the downstream ends of the upstream-side load bodies and the upstream ends of the downstream-side load bodies. These pins

37

and

38

are fastened and connected to each other by fastening members

39

.

As a result of this arrangement, a load is always applied across the entire surface of the running corrugated board sheet in the direction of width of the sheet.

In

FIG. 10

, the load bodies

22

are staggered on the upstream side and downstream side within a single load-applying device

21

. However, it is also possible to arrange the load-applying devices

21

,

28

and

29

shown in

FIG. 1

so that these load-applying devices are respectively staggered as shown in

FIG. 9

or to use a combination of the two configurations described above.

Next, the connection of the load bodies

22

in the sheet conveying direction shown in

FIG. 5

will be described.

Each load body

22

is structured with the downstream side of the corresponding surface pressure applying body

24

left as a free end in the sheet conveying direction, and the upstream side of the surface pressure applying body

24

is fastened in place and allowed to ride. However, in the double facer

1

, the corrugated board sheet S and upper conveyor belt

4

may meander in the sheet conveying direction in some cases. Since the downstream ends of the respective load-applying devices are free ends, meandering of the corrugated board sheet S and upper conveyor belt

4

in the direction of the width of the machine results in the respective load bodies

22

being caught by the meandering so that the load bodies

22

also meander. If this condition worsens, adjacent load bodies

22

may undergo repeated impacts with each other, so that there is a danger that trouble such as one load body riding up over another load body, etc. may occur.

In order to prevent this trouble, the load bodies

22

are connected in the sheet conveying direction as shown in

FIG. 5

, so that the load bodies

22

do not meander. More specifically, for example, spacers

36

are installed above the weight blocks

27

, and connecting members

34

are installed above in the sheet conveying direction via these spacers

36

, and these spacers

36

and the respective weight blocks

27

are fastened together by means of anchoring members

35

. As a result, meandering of the respective load bodies

22

can be prevented.

In

FIG. 3

, the connecting member

35

is disposed in the central portion of the load-applying device

21

. However, the connecting member

35

may be disposed in any position from the upstream side to the downstream side of the load-applying device

21

. Though not shown, a means in which adjacent casings are fastened to each other can be used as another method of preventing meandering of the respective load bodies

22

.

In order to prevent the load bodies

22

as a whole from meandering in the direction of the width of the machine by connecting the load bodies

22

with connecting members

34

, it is also possible to attach side guides

33

to the frame

30

of the double facer

1

. The connecting members

34

are caused to contact the side guides

33

so that the sides (with respect to the direction of width of the machine) of the connecting members

34

that connect the load bodies

22

are regulated as shown in FIG.

6

.

As described above, the load-applying device

21

comprised of the respective load bodies

22

is caused to ride only by the weight of the weight blocks

27

on a stay

23

which is supported on the frame

30

of the double facer

1

by supporting members

31

. Accordingly, no fine gap adjustment or height adjustment according to the thickness of the flute, etc. is required.

Next, the use of the preferred embodiment of the present invention will be described with reference to FIG.

1

.

The single-faced corrugated board sheet and liner introduced into the double facer

1

by the upper conveyor belt and lower conveyor belt

5

are bonded together by being pressed by the pressing device

12

while being heated by the heating device

15

in the heating section

2

of the double facer

1

. Then, when the resulting corrugated board sheet is conveyed into the cooling section

3

, the sheet runs through the cooling section

3

while being held by the upper conveyor belt

4

and lower conveyor belt

5

.

While the sheet is supported from below by the conveying rolls

20

of the supporting conveying device

19

, a load is applied from above by the load-applying devices

21

,

28

and

29

via the upper conveyor belt

4

. In this case, the corrugated board sheet S is loaded only by the weight of the respective load bodies

22

of the load-applying device

21

based on the weight blocks

27

and surface pressure applying bodies

24

. No other load is applied. Accordingly, unnecessarily large pressure such as the pressing force of a pressing device, etc. is not applied.

The respective load bodies

22

are merely caused to ride (by the weight of the weight blocks

27

and surface pressure applying bodies

24

alone) on a stay

23

that is carried on the frame

30

of the double facer

1

via supporting members

31

. Thus, there is absolutely no need for fine gap adjustments or height adjustments according to the thickness of the flute. Since there is almost no damage to the running corrugated board sheet S, crushing of the corrugations can be avoided.

Furthermore, the surface pressure applying body

24

of each load body

22

receives the weight of the weight blocks

27

, and it applies loads on the corrugated board sheet S with this weight as a surface pressure over the entire surface of the surface pressure applying body

24

. Accordingly, no concentrated load caused by the linear pressure of weight rolls, etc. is applied to the corrugated board sheet. In addition, even if the surface pressure applying bodies

24

should receive an upward-pushing force from the corrugated board sheet S or upper conveyor belt

4

, this force is received as a surface pressure. Accordingly, no vibration occurs, and therefore no crushing of the corrugated board sheet S due to roll vibration occurs as it is seen in the case of weight rolls.

The respective load bodies

22

apply a uniform load under the same conditions in the sheet conveying direction. Thus, a non-uniform load balance as a result of a failure to maintain a parallel orientation of the rolls does not occur unlike in the case of use of weight rolls.

Moreover, even in cases where the paper width of the corrugated board sheet that is being produced is narrow, only the load of the weight blocks corresponding to the paper width of the corrugated board sheet that is being produced is applied to the corrugated board sheet. Accordingly, there is no application of the full load of weight rolls (as seen in the case of weight rolls), and there is no crushing of the corrugations due to the application of an excessively large load.

Consequently, a corrugated board sheet of uniform quality can be produced with only a uniform and necessary load being applied in the sheet conveying direction.

As seen from the above, the load-applying device for a double facer provided of the present invention has an extremely simple and easy design. In other words, the load-applying device is caused to ride only by the weight of weight blocks

27

on a stay

23

which is supported on the frame

30

of the double facer

1

via supporting members

31

. Accordingly, complicated mechanism is not required even compared to conventional pressing devices, etc. Thus, the manufacturing cost can be reduced, and there is no need for adjustment of the machinery based on special knowledge or experience.

In addition, setting of the load can be accomplished merely by replacing the weight blocks

27

. Thus, the setting can be simply accomplished with absolutely no need for the replacement of driving members such as springs, etc., and there is no need of setting of the gap between the pressing device and belt.

Moreover, the application of a load to the corrugated board sheet is accomplished by the continuous application of a load in the sheet conveying direction by the load bodies

22

instead of the intermittent application of a load by a pressing device, etc. Accordingly, a good-quality corrugated board sheet that is free of peeling can be produced.

Next, another embodiment of the present invention will be described with reference to

FIGS. 11 through 13

.

A load-applying device

41

consisting of a plurality of load bodies

42

lined up in the sheet conveying direction is disposed above a corrugated board sheet running through the cooling section

3

of the double facer

1

. As seen from

FIG. 11

, the load bodies

42

of the load-applying device

41

are supported by a stay

46

on the frame

30

of the double facer

1

via supporting members

31

as in the above-described embodiment.

One end of an assembly of surface pressure applying bodies

44

formed in the form of a connected chain is fastened to the stay

46

. In the assembly of surface pressure applying bodies

44

, at least two surface pressure applying bodies

44

are connected in the sheet conveying direction by connecting members

43

. The other end of the assembly of surface pressure applying bodies

44

is caused to ride on the upper conveyor belt

4

toward the downstream side of the double facer

1

. The assembly of the surface pressure applying bodies

44

formed in the form of a connected chain is constructed by connecting at least two surface pressure applying bodies

44

. Preferably, however, this assembly is obtained by connecting a plurality of surface pressure applying bodies

44

as shown in

FIG. 11

, etc. In this case, it is generally desirable that the other end of the assembly of surface pressure applying bodies

44

formed into the form of a connected chain be left as a free end; however, the other end can be held by a stay on the downstream side.

Weight blocks

45

are carried on one side of this assembly of surface pressure applying bodies

44

(which is formed in the form of a connected chain with one end fastened to the stay

46

and the other end caused to ride on the upper conveyor belt

4

). Such one side is the opposite side from the side that contacts the upper conveyor belt

4

.

The surface pressure applying bodies

44

formed in the form of a connected chain have a specified thickness. This thickness has an effect substantially the same as that described in the previous embodiment. In other words, the thickness transmits the weight of the weight blocks

45

to the corrugated board sheet as a surface pressure and allows the connecting members

43

to be connected.

Furthermore, it is generally desirable that surface pressure applying bodies

44

that are formed in the form of a connected chain is made of a material which reduces the frictional resistance with the upper conveyor belt

4

, is resistant to the effects of wear caused by friction, and has a good heat resistance. The main materials used in this case include stainless steel sheets, steel sheets whose surfaces have been plated, hard resin type materials such as Teflon and nylon, etc., fiber type materials such as carbon and fibers, etc., and ceramic materials, etc.

Furthermore, it is also possible to execute a surface treatment, that reduces frictional resistance as in the canvas belt used for the upper conveyor belt

4

, on a belt and use such a belt as the surface pressure applying body

44

.

As is clear from

FIGS. 11 through 13

, the weight blocks

45

are members that have a specified length, width and thickness.

The weight, structure and material of the weight blocks

45

are substantially the same as those of the weight blocks

27

in the embodiment described above; accordingly, a detailed description will be omitted here. Furthermore, since the weight blocks

45

are merely carried on the surface pressure applying bodies

44

that are in the form of a connected chain as described above, the weight blocks

45

can be replaced if necessary.

The load bodies

42

as structured above are arranged in the sheet conveying direction as in the embodiment described above. The load bodies

42

form a single load-applying device

41

in the sheet conveying direction, and a plurality of these load-applying devices

41

are disposed in the sheet conveying direction in the cooling section

3

of the double facer

1

in the same manner as described in the above-described embodiment.

In addition, connecting members (not shown), which prevent meandering of the load bodies

42

in the sheet conveying direction, and side guides, which support these connecting members on both sides, etc., are disposed in the same manner as in the above-described embodiment.

Though not shown, the upstream-side and downstream-side load bodies within a single load-applying device

41

can also be constructed with the weight blocks

45

staggered as shown in

FIG. 10

for the above-described embodiment, so that unloaded regions are not generated between the respective load bodies

42

. It is also possible to arrange so that the weight blocks

45

are staggered in the respective load-applying devices

41

disposed in the sheet conveying direction or to use a combination of these two configurations.

Next, the use of another embodiment comprising the load-applying devices

41

and load bodies

42

will be described.

The single-faced corrugated board sheet and liner introduced into the double facer

1

by the upper conveyor belt and lower conveyor belt

5

are bonded together by being pressed by the pressing device

12

while being heated by the heating device

15

in the heating section

2

of the double facer

1

.

Then, when the resulting corrugated board sheet is conveyed into the cooling section

3

, the sheet runs through the cooling section

3

while being held by the upper conveyor belt

4

and lower conveyor belt

5

. While the sheet is supported from below by the conveying rolls

20

of the supporting conveying device

19

, a load is applied from above by the load-applying devices

41

with the upper conveyor belt

4

in between.

In this case, the corrugated board sheet S is given a load only by weight of the weight blocks

45

of the respective load bodies

42

of the load-applying devices

41

and by the weight of the surface pressure applying bodies

44

that are formed into the form of a connected chain. No other load is applied. Accordingly, no unnecessarily large pressure such as the pressing force of a pressing device, etc. is applied.

Furthermore, the respective load bodies

42

are merely caused to ride (by only the weight of the weight blocks

45

and the weight of the surface pressure applying bodies

44

that are formed into the form of a connected chain) on a stay

46

that is carried on the frame

30

of the double facer

1

via supporting members

31

. Accordingly, there is absolutely no need for fine gap adjustments or height adjustments according to the thickness of the flute. In addition, since there is almost no damage to the running corrugated board sheet S, crushing of the corrugations does not occur.

Furthermore, the surface pressure applying bodies

44

(formed into the form of a connected chain) of each load body

42

receive the weight of the weight blocks

45

, and load the corrugated board sheet S with this weight as a surface pressure over the entire surface of the surface pressure applying bodies

44

(formed into the form of a connected chain). Accordingly, no concentrated load caused by the linear pressure of weight rolls, etc. is applied to the corrugated board sheet.

In particular, the surfaces of the load bodies

42

of the load-applying devices

41

that face the corrugated board sheet in this embodiment are comprised of surface pressure applying bodies

44

that are formed into the form of a connected chain. Thus, even if the surface pressure applying bodies

44

that are thus formed into the form of a connected chain should receive an upward-pushing force from the corrugated board sheet S or upper conveyor belt

4

, the upward-pushing force is received as a surface pressure. The upward-pushing force is then absorbed by the connecting members

43

. Accordingly, there is no vibration of the load bodies

42

; and therefore, no crushing of the corrugated board sheet S due to roll vibration occurs unlike in the case of use of weight rolls.

Furthermore, the respective load bodies

42

apply a uniform load under the same conditions in the sheet conveying direction. Thus, a non-uniform load balance as a result of a failure to maintain a parallel orientation of the rolls occurs as in the case of weight rolls.

Moreover, even in cases where the paper width of the corrugated board sheet that is being produced is narrow, only the load of the weight blocks corresponding to the paper width of the corrugated board sheet that is being produced is applied to the corrugated board sheet. Accordingly, an application of the full load of weight rolls would not occur as seen in the case of use of weight rolls, and there is no crushing of the corrugations due to the application of an excessively large load. Consequently, a corrugated board sheet of uniform quality is produced with only a uniform and necessary load being applied in the sheet conveying direction.

As seen from the above, the load-applying device for a double facer of the present invention has an extremely simple and easy design. In other words, the load-applying device is caused to ride only by the weight of weight blocks

45

and by the weight of surface pressure applying bodies

44

that are in the form of a connected chain on a stay

46

which is supported on the frame

30

of the double facer

1

via supporting members

31

. Accordingly, complicated mechanism is not required even compared to conventional pressing devices, etc. Thus, the manufacturing cost can be reduced, and there is no need for adjustment of the machinery based on special knowledge or experience.

In addition, setting of the load can be accomplished merely by replacing the weight blocks

45

. Thus, the setting can be simply accomplished with absolutely no need for the replacement of driving members such as springs, etc., and there is no need of setting of the gap between the pressing device and belt.

Moreover, the application of a load to the corrugated board sheet is accomplished by the continuous application of a load in the sheet conveying direction by the load bodies

42

instead of the intermittent application of a load by a pressing device, etc. Accordingly, a good-quality corrugated board sheet that is free of peeling can be produced.

The load-applying devices and load bodies of the present invention can also be used in the heating section

2

of a double facer

1

.

In the heating section

2

of the double facer

1

, a pressing device is disposed above the paper line of the corrugated board sheet S. The pressing device is comprised of weight rolls or a device in which pressing plates are pressed against the corrugated board sheet by means of a driving device, etc., as described above. However, such weight rolls and pressing devices all suffer from the above-described problems.

As described above, in the load-applying device and load bodies of the present invention the load that is required in absolute terms in order to achieve secure bonding of a corrugated board sheet is applied as a surface pressure. Furthermore, the load-applying device of the present invention has a simple structure in which the load bodies are simply carried by their own weight, and there is absolutely no height adjustment or fine pressure adjustment mechanism for each flute. Thus, there is at least no crushing of the sheet caused by the linear-pressure load and vibration seen in weight rolls, and there is no faulty bonding or bonding imbalance caused by insufficient pressing, etc.

Furthermore, the load-applying device for a double facer of the present invention has an extremely simple and easy structure. More specifically, the load-applying device is caused to ride only by the weight of weight blocks

45

and by the weight of surface pressure applying bodies

44

supported on the frame

30

of the double facer

1

via supporting members

31

. Thus, complicated mechanism is not required even compared to conventional pressing devices, etc. Also, the manufacturing cost is reduced, and there is no need for adjustment of the machinery based on special knowledge or experience.

In addition, setting of the load can be accomplished merely by replacing the weight blocks

45

. Thus, the setting can be simply accomplished with absolutely no need for the replacement of driving members such as springs, etc., and there is no need of setting of the gap between the pressing device and belt.

Moreover, the application of a load to the corrugated board sheet is accomplished by the continuous application of a load in the sheet conveying direction by the load bodies

42

instead of the intermittent application of a load by a pressing device, etc. Accordingly, a good-quality corrugated board sheet with no peeling of the sheet can be produced.

In the embodiment in which the load-applying device and load bodies of the present invention are used in the heating section

2

of a double facer

1

, as shown in

FIG. 14

, load-applying devices

50

,

51

and

52

are disposed above the running corrugated board sheet S. In the heating section

2

, it is desirable that load-applying devices be disposed over the entire surface in the sheet conveying direction. However, it is sufficient to install at least one load-applying device in the sheet conveying direction.

In the embodiment shown in

FIG. 14

, three load-applying devices

50

,

51

and

52

which have the same mechanism are disposed in the sheet conveying direction.

The three load-applying devices

50

,

51

and

52

shown in

FIG. 14

basically have the same structure as the load-applying device

21

and load bodies

22

used in the cleaning section

3

. Accordingly, a detail description will be omitted, and a brief description thereof will be given below.

As a typical example, the structure of the load-applying device

50

disposed on the furthest upstream side of the heating section

2

will be described. In the load-applying device

50

, as shown in

FIG. 15

, a plurality of load bodies

53

are disposed in the sheet conveying direction and form a single load-applying device.

The load bodies

53

of the load-applying device

50

are supported on a stay

54

of the frame

30

of the double facer

1

via supporting members

31

. In each load body

53

, one end of a surface pressure applying body

55

is fastened to the stay

54

, while the other end of the surface pressure applying body

55

is caused to ride on the upper conveyor belt

4

toward the downstream side of the double facer

1

. It is generally desirable that the other end of the surface pressure applying body

55

be left as a free end. However, the other end may also be held by a stay on the downstream side.

Furthermore, weight blocks

58

are disposed inside frame bodies

56

and

57

that are on one side of each surface pressure applying body

55

which is caused to ride on the upper conveyor belt

4

with one end fastened to the stay

54

. Such one side is opposite from the side that contacts the upper conveyor belt

4

.

The thickness and material of the surface pressure applying bodies

55

may be the same as those of the surface pressure applying bodies

24

and

44

used in the cooling section

3

. The heating device

15

is disposed beneath the running corrugated board sheet S in the case of the surface pressure applying bodies

55

used in the heating section

2

. Accordingly, a material which has a greater heat resistance than the material of the surface pressure applying bodies used in the cooling section

3

is required.

The structure, material and weight of the weight blocks

58

are the same as those of the weight blocks

27

used in the cooling section

3

may be used. However, the heating device

15

is disposed beneath the running corrugated board sheet S in the case of the weight blocks

58

used in the heating section

2

. Accordingly, a material that has a greater heat resistance than the material of the weight blocks

27

used in the cooling section

3

is required.

Furthermore, in regard to the installation of the weight blocks

58

to the surface pressure applying bodies

55

, the weight blocks

58

are simply carried on the surface pressure applying bodies

55

; and this is most desirable. However, it is also possible to mount the weight blocks

58

using an adhesive tape, glue, etc., so that the weight blocks

58

do not fall off of the surface pressure applying bodies

55

.

In the present embodiment, thus the weight blocks

58

are lined up in an orderly manner on the surface pressure applying bodies

55

. Also, casings

56

and

57

which accommodate the weight blocks

58

are disposed above the surface pressure applying bodies

55

so that the weight blocks

58

do not fall off. The casings

56

and

57

have the same structure as the casings

25

and

26

used in the cooling section

3

. Furthermore, though not shown, it is also possible to use structural bodies in which frame bodies are directly formed in an upright position on the surface pressure applying bodies, so that the surface pressure applying bodies themselves function as casings that can accommodate the weight blocks.

Since the weight blocks

58

are merely carried on the surface pressure applying bodies

55

, the weight blocks

58

can be replaced upon necessity.

Furthermore, a plurality of load bodies

53

are disposed in the sheet conveying direction and form a single load-applying device

50

, and these load bodies

53

apply load on the corrugated board sheet S from above with the upper conveyor belt

4

in between. As in the above-described embodiments, the load bodies

53

are set in accordance with the paper width of the corrugated board sheet S. Also, the two ends (with respect to the direction of width of the sheet) of the corrugated board sheet S that is being produced are never positioned between adjacent load bodies

53

.

It is also possible to dispose the load bodies

53

and load-applying device

50

so that these elements are staggered with respect to the sheet conveying direction as in the above-described embodiments. Moreover, in regard to connecting members used to prevent meandering and the prevention of meandering of the load bodies as a whole, meandering can be prevented by connecting the respective load bodies

53

and supporting the sides of the connecting members in the same manner as in the above-described embodiments.

As described above, the load-applying device

50

comprised of the respective load bodies

53

of the present invention is caused to ride by the weight of the weight blocks

58

and by the weight of the surface pressure applying bodies

55

alone on a stay

54

which is supported on the frame

30

of the double facer

1

via supporting members

31

. Accordingly, complicated mechanism is not required even compared to conventional pressing devices, etc. Consequently, the manufacturing cost can be reduced, and there is no need for adjustment of the machinery based on special knowledge or experience.

In addition, setting of the load can be accomplished merely by replacing the weight blocks

58

. Thus, the setting can be simply accomplished with absolutely no need for the replacement of driving members such as springs, etc., and there is no need of setting of the gap between the pressing device and belt.

Moreover, the application of a load to the corrugated board sheet is accomplished by the continuous application of a load in the sheet conveying direction by the load bodies

53

instead of the intermittent application of a load by a pressing device, etc. Accordingly, a good-quality corrugated board sheet having no peeling of the sheet can be produced.

Next, the use of a preferred embodiment in which the device of the present invention is used in the heating section

2

of a double facer

1

will be described with reference to

FIGS. 14 and 15

.

The single-faced corrugated board sheet and the liner are conveyed from the upstream side of the double facer

1

and introduced into the heating section

2

by the upper conveyor belt

4

and lower conveyor belt

5

. In the heating section

2

, the corrugated board sheet S is heated from below by the heating device

15

and is applied with load from above by the load-applying device

50

so that the sheet and the liner are bonded.

In the load-applying device

50

, the respective load bodies

56

apply load to the corrugated board sheet S only by the weight of the weight blocks

58

and by the weight of the surface pressure applying bodies

55

, and no other load is applied. Accordingly, unnecessarily large pressure such as the pressing force of a pressing device, etc. is not applied.

Furthermore, the respective load bodies

53

are merely caused to ride by the weight of the weight blocks

58

and by the weight of the surface pressure applying bodies

55

on a stay

54

that is carried on the frame

30

of the double facer

1

via supporting members

31

. Accordingly, there is absolutely no need for fine gap adjustments or height adjustments that would be required by the thickness of the flute. Since there is thus almost no damage to the running corrugated board sheet S, crushing of the corrugations does not occur.

Furthermore, the surface pressure applying body

55

of each load body

53

receives the weight of the weight blocks

58

; and using its entire surface, the surface pressure applying body

55

applies load to the corrugated board sheet S with such weight as a surface pressure. Accordingly, no concentrated load caused by the linear pressure of weight rolls, etc. is applied to the corrugated board sheet. Even if the surface pressure applying bodies

55

should receive an upward-pushing force from the corrugated board sheet S or upper conveyor belt

4

, this force is received as a surface pressure. Accordingly, there is no vibration; and therefore no crushing of the corrugated board sheet S due to roll vibration occurs as seen in the case of weight rolls.

Furthermore, the respective load bodies

53

apply a uniform load under the same conditions in the sheet conveying direction. Thus, a non-uniform load balance as a result of a failure to maintain a parallel orientation of the rolls does not occur unlike in the case of use of weight rolls. Accordingly, a corrugated board sheet of uniform quality is produced at a uniform and minimum required load in the sheet conveying direction.

Though not shown and not described in detail, load bodies and a load-applying device of the same structure as the load-applying device

41

, which is comprised of the load bodies

42

constructed according to the embodiment of

FIGS. 11 through 13

, may be used in the heating section

2

.

Next, a modification of the surface pressure applying body will be described.

The surface pressure applying bodies

24

,

44

and

55

described above in the load-applying devices

21

,

41

and

50

are all split in the sheet conveying direction, and weight blocks

27

,

45

and

58

are disposed on the respective surface pressure applying bodies

24

,

44

and

55

.

FIGS. 16 and 17

show an embodiment used in the cooling section

3

.

FIG. 16

is a top view of a surface pressure applying body, and

FIG. 17

is a sectional view thereof in the sheet conveying direction.

Here, a surface pressure applying body

62

is disposed above the corrugated board sheet S so as to face the corrugated board sheet S. The surface pressure applying body

62

covers the entire surface of the corrugated board sheet S. More specifically, the surface pressure applying body

62

is a single surface pressure applying body which has a width that is slightly greater than the maximum design paper width of the corrugated board sheet that is to be produced.

The length, thickness and material of the surface pressure applying body

62

may be basically the same specifications as those of the various types of surface pressure applying bodies described above. However, in regard to the material in particular, it is desirable to use a material that possesses ample softness. With such a material, no non-uniform surface pressure is applied to the corrugated board sheet in the sheet conveying direction, and the surface pressure applying body shows a good fit with the corrugated board sheet S. For example, a cotton-form canvas belt of the same material as the upper conveyor belt, a resin or plastic film, a ceramic material such as carbon, etc., or a metal material such as a steel, copper plate, stainless steel, etc. may be used. A thin material is desirable in all of these materials.

By way of disposing a plurality of weight blocks

63

on the surface pressure applying body

62

in the direction perpendicular to the sheet conveying direction, a load body

61

is obtained.

In the load-applying device

60

constructed with the elements described above, when the corrugated board sheet S passes through the cooling section, the load body

61

applies a load to the upper surface of the corrugated board sheet S. The load body

61

has a plurality of weight blocks

63

disposed in the sheet conveying direction and comprised of a surface pressure applying body

62

that covers the entire surface of the corrugated board sheet S in the direction of width of the sheet S. Since the surface pressure applying body

62

is, as described above, made of a material that has ample softness, the surface pressure applying body

62

shows a good fit with the corrugated board sheet S. Thus, a uniform minimum required load is applied to the entire surface of the corrugated board sheet S. As a result, a corrugated board sheet of uniform quality is produced with a minimum required load that is uniform in the sheet conveying direction being applied.

Furthermore, since the weight blocks

63

are merely carried on the surface pressure applying body

62

as described above, these weight blocks

63

can be replaced upon necessity. It is also possible to prevent the generation of unloaded regions on the corrugated board sheet S by way of disposing the weight blocks

63

in a staggered pattern in the sheet conveying direction as shown in FIG.

18

.

Though not shown, it is possible to install frame bodies that accommodate the weight blocks

63

on the surface pressure applying body

62

. Moreover, though likewise not shown, it goes without saying that the embodiment of

FIGS. 16 and 17

can be used in a double facer in which an upper conveyor belt is present between the corrugated board sheet S and the surface pressure applying body

62

. Furthermore, though

FIGS. 16 and 17

illustrate an embodiment used in the cooling section

3

, it goes without saying that this embodiment can be used in the heating section

2

.

Furthermore, the load-applying device of the present invention that is comprised of the load bodies can be used in both the heating section

2

and cooling section

3

of a double facer

1

. This provides a synergistic effect, and a good-quality corrugated board sheet with no crushed corrugations or faulty bonding is realized by means of a simple, low-cost apparatus.

Furthermore, in the load-applying device of the present invention, it is not an essential condition that the respective load bodies apply a load to the corrugated board sheet with an upper conveyor belt in between. For example, in cases where the lower conveyor belt is a suction conveyor of the type disclosed in Japanese Patent Application Laid-Open (Kokai) No. 9-117976, etc., direct loading is possible in which the respective load bodies of the load-applying device contact the corrugated board sheet directly and apply a direct load. Furthermore, the respective load bodies of the load-applying device may also contact the corrugated board sheet directly and apply a direct load in the case of a double facer which does not require an upper conveyor belt in the heating section, either.

As seen from the above, in the load-applying device for a double facer provided by the present invention, the device has a simple structure in which the respective load bodies are simply caused to ride on the upper surface of the corrugated board sheet by the weight of weight blocks. Accordingly, the structure is an extremely simple, and the load-applying device has absolutely no height adjustment device for adjusting the height according to respective flutes of the corrugated board sheet or pressure adjustment device for adjusting the pressure. Consequently, the cost can be reduced. In addition, since the structure is simple, there are no complicated adjustments, maintenance is easy, and the work burden on the operator can be reduced.

The respective load bodies receive the weight of the weight blocks and apply the weight as a surface pressure so that only the load that is required for bonding the corrugated board sheet is applied to the corrugated board sheet. Thus, no concentrated load based on a linear pressure (as seen in the case of weight rolls) is applied to the corrugated board sheet.

Furthermore, even if an upward-pushing force is received from the corrugated board sheet or upper conveyor belt, this force is received as a surface pressure. Thus, there is no vibration, and there is no crushing of the corrugated board sheet due to roll vibration as seen in the case of weight rolls.

In addition, the respective load bodies apply a uniform load under the same conditions in the sheet conveying direction. Thus, there is no non-uniform load balance resulting from the failure to maintain the parallel orientation of rolls (as seen in the case of weight rolls). Accordingly, a corrugated board sheet of uniform quality is produced at a uniform load in the sheet conveying direction.

Since no vibration occurs in the load bodies, noise is not generated. This helps to improve the working environment of the operator as well as the surrounding regional environment.

Furthermore, since the surface pressure applying bodies that carry the weight blocks of the load bodies are constructed with a shape that covers the entire surface of the corrugated board sheet, there is little escape of moisture even if the corrugated board sheet is heated. Thus, warping of the corrugated board sheet tends not to occur.

Furthermore, the load-applying device for a double facer of the present invention has an extremely simple and easy structure. In other words, the device is caused to ride only by the weight of the weight blocks on a stay that is supported on the frame of the double facer via supporting members. Thus, no complicated mechanism is required even compared to conventional pressing devices, etc. The manufacturing cost can be reduced, and there is no need for adjustment of the machinery based on special knowledge or experience.

In addition, setting of the load can be accomplished merely by replacing the weight blocks. Such a setting thus can be simply accomplished with absolutely no need for the replacement of urging elements such as springs, etc. Further, setting of the gap between the pressing device and belt is also not required.

Moreover, the application of a load to the corrugated board sheet is accomplished by a continuous application of a load in the sheet conveying direction by the load bodies instead of the intermittent application of a load by a pressing device, etc. Thus, a good-quality corrugated board sheet that is free of peeling of the sheet can be produced.

Number	Name	Date	Kind
4023481	Keeny	May 1977	A
5788803	Sissons et al.	Aug 1998	A
6257296	Pallas et al.	Jul 2001	B1

Load-applying device for a double facer

Information

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CPC

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US Referenced Citations (3)