Double facer

Abstract

 A double facer in a corrugate machine has weight rolls (4) for pressing a double-faced corrugated cardboard sheet in a heating part against a heating box via a canvas belt (14). In order to comparate for uneven pressing effects of the weight rolls along the widthwise direction of the corrugated cardboard sheet due to deformation of the heat­ing box caused by temperature change, a plurality of weight rolls are disposed as aligned in the widthwise direction of the corrugated cardboard sheet, and the weight rolls are arranged so as to be able to move up and down respec­tively and individually. Preferably, weight roll rows in each of which a plurality of weight rolls are aligned in the widthwise direction of the corrugated cardboard sheet, are disposed in multiple as arrayed in the direction of traveling of the corrugated cardboard sheet, and the weight rolls in the adjacent rows are disposed in a staggered relationship so as to form a checker pattern.

Description

BACKGROUND OF THE INVENTION:

Field of the Invention:

[0001] The present invention relates to a double facer that is available in a heating part of a double facer system within a corrugate machine.

Description of the Prior Art:

[0002] A general construction of the heretofore known double facer system is illustrated in Fig. 10, and de­tailed structures of a weight roll section in the double facer system in the prior art and problems involved in these structures are shown in Figs. 5 to 9.

[0003] As shown in Fig. 10, a double facer system in a corrugate machine is constituted of a heating part 10 and a cooling part 15, and this is a system for manufac­turing various kinds of double-faced corrugated cardboard sheet 3 by sticking a single-faced corrugated cardboard sheet 1 produced by a single facer in the preceding stage and a liner 2 to each other. The above-mentioned heating part 10 is composed of a preheater section 16, a heating box (hot plate) section 13, a canvas belt section 14, a pressing section 17 and the like, and the cooling part 15 is composed of a conveyor belt section 18, a canvas belt section 14, a pressing section 19 and the like.

[0004] Now explaining the operation of the above-­ described double facer system in the prior art, a single-­faced corrugated cardboard sheet 1 produced by the single facer in the preceding stage has starch paste 24 applied to crests 20 of its corrugations in a glue machine 20, and then it is conveyed into the heating part 10 of the double facer system. On the other hand, the liner 2 is preheated by the preheater 16, and is likewise conveyed into the heating part 10 of the double facer system. Thus the single-faced corrugated cardboard sheet 1 and the liner 2 conveyed into the heating part 10 in the double facer system join and overlap with each other at an intro­ducing port of the heating part 10, and then they are pinched between the canvas belt 14 driven to travel by a roll 22 and the heating box 13, and conveyed as held pressed via the canvas belt 14 by weight rolls 23. When they pass through the heating part 10, the starch paste 24 is solidified, hence the single-faced cardboard sheet 1 and the liner 2 are sticked to each other, and a double-­faced corrugated cardboard sheet 3 is formed. The cooling part 15 in the next step is a cooling section for the double-faced cardboard sheet 3, in which the corrugated cardboard sheet 3 is pinched by upper and lower conveyor belts 14 and 18 and is conveyed out under a condition where an appropriate pressing force is applied to the corrugated cardboard sheet 3 by means of pressing rolls 25, and then it is fed to the next step of the process.

[0005] The weight rolls 23 of the double facer in the prior art are constructed as shown in Figs. 5 to 7, in which an integral type weight roll 23 having such length that it can press the corrugated cardboard sheet over the entire width is pivotably secured to one ends of a pair of arms 26 via bearings provided at its opposite ends, and the other ends of the same arms 26 are pivotably secured to a fulcrum shaft 9 via bushes or bearings 8. The oppo­site ends of the fulcrum shaft 9 are fixedly secured to frames 30 positioned on the opposite sides of the heating part 10. The weight rolls 23 each of which is constructed as described above, are disposed as arrayed in the travel­ing direction of the corrugated cardboard sheet 3.

[0006] In the above-described pressing section in the prior art, there was a shortcoming that in the case where the heating box 13 has deformed along the widthwise direc­tion of the device due to temperature change, uneven distribution (variation) of the pressing force W exerted by the weight roll 23 corresponding to the amount of deformation, cannot be avoided. The upper surface temper­ature of the heating box 13 preset so as to promote stick­ing of the single-faced corrugated cardboard sheet 1 to the liner 2, is far higher than the temperature of the preheated liner 2 which slides along the heating box 13, hence the upper surface of the heating box 13 would con­tract due to the fact that during the period when the liner 2 moves through the heating part 10, heat is taken away from the upper surface of the heating box 13 to the liner 2, and normally the upper surface would deform into a concaved shape along the widthwise direction as shown in Fig. 9. Accordingly, there occurs a tendency that pressing forces at the opposite ends become large as com­pared to the central portion of the machine, and so, uneven pressing forces W are applied to the surface of the double-­faced corrugated cardboard sheet 3 as shown in Fig. 8. It is to be noted that the amount of deformation of the heat­ing box 13 would be increased or decreased depending upon the amount of heat released from its upper surface, and it can be arbitrarily changed by changing a traveling speed, a specification of a paper sheet (material, thick­ness and width), paste and the like.

[0007] When the upper surface of the heating box 13 deforms into a concaved shape in the above-described manner, while the weight roll 23 would flex to a certain extent due to its own weight, it cannot make the deforma­tion along the concaved surface of the heating box 13, and hence it becomes impossible to apply a uniform weight along the widthwise direction of the corrugated cardboard sheet 3. In other words, as the deformation into a concaved shape becomes larger, there occurs a tendency that the weights at the opposite end portions become large and at the central portion a very small weight is applied. If a corrugated cardboard sheet is manufactured under such condition, poor sticking in the corrugated cardboard sheet would occur, resulting in a loss cardboard sheet, and it becomes impossible to maintain the quality of the cor­rugated cardboard sheet homogeneous due to uneven pressing along the widthwise direction.

[0008] As described above, in the prior art between the upper surface temperature of the heating box 13 which was preset so as to assist sticking between the liner 2 traveling as held in slide contact with the upper surface and the single-faced cardboard sheet 1, and the temper­ature of the preheated liner which slides along the upper surface of the heating box 13, is present the relation of [heating box temperature (about 180°C)] > [liner temper­ature (about 100°C)], and while the liner 2 is being conveyed through the heating part 10, heat is taken away from the heating box 13 to the liner 2, thus the upper surface of the heating box 13 would contract due to the fact that the upper surface temperature of the heating box 13 is lowered, and the upper surface deforms into a concaved shape along the widthwise direction as shown in Fig. 9. Whereas, the weight roll 23 cannot make the deformation along the concaved surface of the hot plate, although it flexes to a certain extent due to its own weight. Accordingly, the pressing force exerted by the weight roll 23 would become uneven along the widthwise direction of the machine. In other words, there occurs a tendency that pressing forces at the opposite end por­tions become large as compared to the pressing force at the central portion of the machine. Thus, the prior art double facer system involved the problems that loss sheets were produced due to poor sticking caused by the uneven pressing and it was difficult to insure the quality of the produced corrugated cardboard sheet.

SUMMARY OF THE INVENTION:

[0009] It is therefore one object of the present inven­tion to provide a novel double facer, in which the above-­described problems in the prior art can be resolved by allowing weight rolls to successively follow the deforma­tion of a hot plate of a heating box during continuous operation of the double facer, and thereby always uniform weights along the widthwise direction can be applied to a corrugated cardboard sheet.

[0010] According to one feature of the present invention, there is provided a double facer having weight rolls con­structed so as to press a double-faced corrugated cardboard sheet in a heating part against a heating box via a canvas belt, in which a plurality of weight rolls are disposed as aligned in the widthwise direction of the corrugated card­board sheet, and the weight rolls are arranged so as to be able to move up and down respectively and individually.

[0011] According to another feature of the present invention, there is provided the above-featured double facer, in which weight roll rows in each of which a plu­rality of weight rolls are aligned in the widthwise direc­tion of the corrugated cardboard sheet, are disposed in multiple as arrayed in the direction of traveling of the corrugated cardboard sheet, and the weight rolls in the adjacent rows are disposed in a staggered relationship so as to form a checker pattern.

[0012] According to the present invention, since such structure that each weight roll in the prior art is divided into a plurality of minor weight rolls along the axial direction of the weight roll and the respective minor weight rolls are respectively swingable independently of each other, is employed, always uniform pressing forces can be obtained regardless of deformation of the heating box, hence it becomes possible to make heat and tension applied to the corrugated cardboard sheet uniform along the widthwise direction, and so manufacture of a corrugated cardboard sheet of excellent quality becomes possible. In addition, by appropriately disposing a plurality of sets of weight rolls in juxtaposition along a traveling direc­tion of the corrugated cardboard sheet, uniform pressing forces over the sheet traveling direction of the corrugate machine can be applied to the double-faced corrugated cardboard sheet.

[0013] The above-mentioned and other objects, features and advantages of the present invention will become more apparent by reference to the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

[0014] In the accompanying drawings:

Fig. 1 is a schematic side view of an entire weight roll section in a double facer according to one preferred embodiment of the present invention;

Fig. 2 is an enlarged partial plan view partly in cross-section of an essential part of the weight roll section in Fig. 1;

Fig. 3 is a side view of the portion shown in Fig. 2;

Fig. 4 is a weight (pressing force) distribution diagram in the case of employing the weight rolls shown in Fig. 3;

Fig. 5 is a schematic side view of an entire weight roll section in a double facer in the prior art;

Fig. 6 is an enlarged front view of a weight roll in Fig. 5;

Fig. 7 is a side view of weight rolls in Fig. 6;

Fig. 8 is a weight (pressing force) distribution diagram in the case of employing the weight rolls in the prior art;

Fig. 9 is a schematic view to be referred to for explaining the problems involved in the double facer in the prior art; and

Fig. 10 is a schematic side view showing an entire construction of a general double facer system in a known corrugate machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

[0015] Now the present invention will be described in greater detail in connection to one preferred embodiment of the invention illustrated in Figs. 1 to 4. With regard to the function of a double facer in a corrugate machine, that is, with regard to a series of working steps and a schematic construction of an apparatus for manufacturing a double-faced corrugated cardboard sheet 3 by sticking a single-faced corrugated cardboard sheet 1 produced by a single-facer in the preceding step and a liner 2 carried in through a separate route, it is quite similar to that described above in connection to the prior art. In these figures, reference numeral 1 designates a single-faced corrugated cardboard sheet, numeral 2 designates a liner, numeral 3 designates a double-faced corrugated cardboard sheet, numeral 7 designates a pin, numeral 8 designates a bush or a bearing, numeral 9 designates a fulcrum shaft, numeral 10 designates a heating part, numeral 12 designates a stopper, numeral 13 designates a heating box, numeral 14 designates a canvas belt, and these are the same as de­scribed previously in connection to the prior art.

[0016] The weight rolls 4 shown in Figs. 1 to 3 respec­tively have a individual roll shape formed by dividing a single weight roll extending over the entire width of the corrugated cardboard sheet as used in the prior art into a plurality of shorter weight rolls aligned in the width­wise direction, each of the weight rolls 4 is pivotably supported by pins 7 projected from free ends of a pair of arms 6 via self-aligning bearings 5 provided at its oppo­site ends, and the other ends of the same arms 6 are pivotably secured to the fulcrum shaft 9 via bushes or bearings 8. In addition, the opposite ends of the fulcrum shaft 9 are fixedly secured to frames not shown which are positioned on the opposite sides of the heating part 10.

[0017] As shown in Fig. 2, the weight rolls 4 formed in the above-described manner are aligned in multiple in the widthwise direction of the corrugated cardboard sheet to form a weight roll row, and the weight rolls 4 in adjacent two rows are disposed in a staggered relationship so as to form a checker pattern along the traveling direc­tion of the double-faced corrugated cardboard sheet 3. It is to be noted that while the arms 6 for pivotably supporting one row of weight rolls 4 and arms 11 for pivot­ably supporting another row of weight rolls 4 disposed at adjacent positions are illustrated to be pivotably supported from the same fulcrum shaft 9 in the figure, modification could be made such that the row of arms 6 and the row of arms 11 are pivotably supported respectively from different fulcrum shafts. The stoppers 12 are provided for the pur­pose of restraining the position of the arms 6 and 11 in the axial direction.

[0018] According to the present invention, since a pre­determined number of rows of weight rolls are disposed along the traveling direction of the corrugated cardboard sheet 3 as shown in Fig. 1 and the respective weight rolls 4 can swing individually, even in the event that the upper surface of the heating box 13 has deformed along the width­wise direction due to temperature variations, the respective weight rolls 4 can swing by the distance corresponding to the amount of deformation so as to follow the deformation, and therefore, always uniform pressing forces W can be applied to the surface of the double-faced corrugated card­board sheet via the canvas belt 14 as shown in Fig. 4. Accordingly, heat and tension applied to the corrugated cardboard sheet 3 can be made uniform over the entire region in the widthwise direction, and so, various troubles in the prior art as described previously can be eliminated.

[0019] Since the double facer according to the present invention is constructed in the above-described manner, uniform pressing forces over the entire region in the widthwise direction of the liner sliding along the heating box can be applied to the corrugated cardboard sheet. Accordingly, a uniform heating temperature and a uniform frictional resistance (tension) can be applied to the liner over its entire width, and so, prevention of loss sheets caused by poor sticking or the like and insurance of quality of a corrugated cardboard sheet can be expected.

[0020] While a principle of the present invention has been described above in connection to one preferred em­bodiment of the invention, it is intended that all matter contained in the specification and illustrated in the accompanying drawings shall be interpreted to be illus­trative and not as limitation to the scope of the inven­tion.

Claims

1. A double facer having weight rolls con­structed so as to press a double-faced corrugated cardboard sheet in a heating part against a heating box via a canvas belt, characterized in that a plurality of weight rolls are disposed as aligned in the widthwise direction of the corrugated cardboard sheet, and said weight rolls are arranged so as to be able to move up and down respectively and individually.

2. A double facer as claimed in Claim 1, characterized in that weight roll rows in each of which a plurality of weight rolls are aligned in the widthwise direction of the corrugated cardboard sheet, are disposed in multiple as arrayed in the direction of traveling of the corrugated cardboard sheet, and the weight rolls in the adjacent rows are disposed in a staggered relation­ship so as to form a checker pattern.

Drawing