JPH0628932B2 - Double phaser - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a double facer, which is a papermaking machine for continuously producing double-faced corrugated board sheets.

(Prior Art) FIG. 9 shows a side sectional view of a conventional double facer. In the figure, the single-faced corrugated board 1 made of a single facer (not shown) in the previous step enters the double facer 5 after the starch paste 13 is applied to the corrugated core paper by the glue machine 14. On the other hand, the liner 2 is preheated by the preheater 4 and similarly enters the double facer 5. The single-faced cardboard sheet 1 and the liner 2 that have entered the double facer 5 are sandwiched between the belt 8 driven by the roll 12 and the heating box 9 in the heating part 6, and the weight rolls arranged in line on the back side of the belt 8 are also provided. It is pressurized at 10 and transferred.

When the single-faced corrugated board 1 and the liner 2 pass through the heating part 6, heating of the heating box 9 having high-temperature steam inside causes the attached starch paste to be gelatinized, so that the corrugated core paper of the single-sided corrugated board sheet 1 is formed. Step and Liner 2
Are bonded together to form the double-sided corrugated board sheet 3. The double-faced corrugated cardboard sheet 3 is carried out in the subsequent cooling part 7 while being sandwiched between the belt 8 and the lower belt 11,
It is sent to the next process.

Here, the weight roll 10 in the conventional double facer is intended to apply the laminating pressure to the double-faced corrugated cardboard sheet 3 and to promote heating in the heating part 6, but at the same time, the following problems occur. Had.

That is, since the pressure applied by the weight roll 10 acts on the double-sided corrugated board sheet 3 via the belt 8 as a linear pressure due to its own weight, particularly in the case of a corrugated cardboard sheet or a narrow corrugated board sheet which is soft against local pressure, The linear pressure applied by the weight roll 10 becomes too large, causing step collapse as shown in FIG.

The main reason for this is that the heating of the glue adhering part by the heating box 9 is mainly due to the conduction heat through the vessel wall of the box 9 and the liner 2 that is in contact with it, so that both are crimped as much as possible. This is because it is necessary to enhance the thermal conductivity, and therefore it is necessary to apply a considerably strong pressing force to the both sides from the back surface of the single-faced corrugated board sheet 1 by the weight roll 10. Moreover, since the heating method is such an intermittent heating method, the heating efficiency is low, the heating part is inevitably long, and the production speed is low.

(Problems to be Solved by the Invention) As described above, according to the heating and pressurizing means in the conventional double facer, since the heating depends on the heat conduction, most of the heat energy is wasted and the heat conductivity is high. Since a large amount of pressure is required to maximize the temperature, a step collapse phenomenon may occur, resulting in waste of energy, generation of defective products, and hindrance to miniaturization of the device.

The present invention has been developed in view of these points, and an object of the present invention is to provide a double facer in which all of the above-mentioned conventional problems are eliminated by improving heating efficiency and simultaneously using a uniform pressing means.

(Means for Solving Problems) Therefore, the present invention provides a double facer for manufacturing a double-faced corrugated sheet by attaching a liner to the corrugated core paper of the single-faced corrugated sheet, and an appropriate sheet supporting means on the back side of the single-faced corrugated sheet. And a dielectric heating device is disposed on the surface side of the liner with an appropriate gap from the liner surface, and an air jetting device that covers the device and generates static pressure by air between the liner surface and the liner. Is provided. This is a means for solving the problem.

(Function) Utilizing the fact that one side of the corrugated board sheet absorbs much more power in the glue part than in the paper part than in the dielectric heating device, applying a high-frequency voltage between the electrodes to selectively dielectrically heat the glue to improve efficiency. Adhesive and dry. At the same time, air pressure from the air jetting device is applied to the liner surface of the corrugated board sheet to uniformly and uniformly press the single-sided corrugated board sheet and the liner to be attached, thereby further strengthening the adhesion between the two.

(Example) Hereinafter, the present invention will be described based on Examples of the drawings.
FIG. 1 is a side sectional view showing the entire double facer which is an embodiment of the present invention. This apparatus includes a conventional heating box 9 shown in FIG.
Instead of the weight roll 10 arranged on the back surface of the belt 8,
A single-sided corrugated cardboard sheet 1 and a liner 2 interposed, and a dielectric heating device having a grid electrode 15 on one surface, and covering the device.
An air jetting device 16 is arranged so as to face the liner surface, and a guide roll 10 'for keeping the belt surface flat is arranged at a proper position on the back surface of the belt 8.

As the arrangement of the grid electrode 15, as shown in FIG. 2 to FIG. 4, there are three types of arrangement that can be arranged in parallel, at right angles, or obliquely with respect to the flow direction of the corrugated cardboard sheet. As shown in the figure, the size and shape are determined under the condition of Lsin θ ≧ P. Here, L represents the width of the corrugated board sheet, P represents the pitch interval of the electrodes, and θ represents the inclination angle of the electrodes in the corrugated board width direction.

Next, the dielectric heating by the grid electrode will be described. When a high frequency alternating electrode is applied to the grid electrode 15, an electric field is generated between the respective electrodes as shown in FIG. Incidentally, FIG. 6 shows a cross section taken along line AA of FIG.
The generation of the electric field is the same in the cases of FIGS. 3 and 4.

By the way, the electric power absorbed inside by the dielectric heating is f
・ Proportional to E ² · ε · tan δ. Here, f is the frequency, E is the strength of the electric field, ε is the relative permittivity of the heated object, and tan δ is the dielectric loss coefficient of the heated object. By the way, since the value of f · E ² ε · tan δ in the glue part is 20 to 30 times higher than that of the paper part, the absorbed power is concentrated in the glue part, and the paste material is gelatinized and dried. Will be promoted. In the case of conventional heating with a heating box, heat conduction is through the paper, and about 70% of the heat is spent to raise the temperature of the paper part, but this dielectric heating is an efficient heating. Is the way.

Next, the pressing means required for bonding the corrugated board sheets will be described. In the present invention, instead of the conventional pressurizing method by the weight roll, the pressurizing method by the static air pressure by the air ejecting device 16 is adopted. FIG. 7 and FIG. 8 show an example in which the static pressure pads 18 are arranged in a row, and an example in which the entire box is a single static pressure container 19. The arrows shown in these drawings indicate the flow of jet air, and the pressurized air forms a static pressure region between the pad and the corrugated cardboard sheet facing each other while being pressed into the container. , It acts uniformly and effectively as the bonding pressure for corrugated board sheets.

The grid electrodes 15 of the dielectric heating device are accommodated in the air ejecting devices 16, and the corrugated cardboard sheet 3 is a belt which is a supporting member of the corrugated cardboard sheet due to the air pressure from the air ejecting device as described above. Since it is pressed and supported in a non-contact manner on the 8 side, on the grid electrode array,
There is no need for inclusions such as corrugated cardboard sheet support materials that cause a loss of electric power, which is extremely advantageous in terms of dielectric heating. As the sheet supporting means installed on the back side of the single-sided corrugated cardboard, a belt structure which has been conventionally adopted, or an appropriate supporting means such as an air jetting device or a roller for generating air dynamic pressure or static electricity can be adopted. The type and structure of the means are not limited.

Here, it is also possible to use high-temperature dry air as the air to be supplied to the air jetting device 16, and in this case, in addition to the pressurizing action, in addition to the effect of promoting the drying of the glue portion,
The effect of improving the insulation around the electrodes and preventing electrical damage due to discharge, leakage, etc. can also be expected.

Next, the operation of manufacturing double-faced corrugated board by the apparatus of this embodiment will be described with reference to FIG. The single-faced corrugated cardboard sheet 1 and the liner 2 to which the sizing agent is attached are merged at the entrance of the heating part 6 ′ by the transport roll 22 and transported. In the heating part 6 ′, as described above, the electric field is particularly concentrated on the glue surface portion of the corrugated cardboard sheet by the dielectric heating device having the grid electrode 15 installed on the lower surface side of the sheet, and at the same time, the sheet is discharged from the air jetting device 16. Uniform pressure is applied by static air pressure, and the glued portion is heated in a pressure-bonded state, and the glue material is gelled and dried and adhered. Further, as described above, by using high temperature air having an air temperature of 150 to 180 ° C.,
The effect of further heating gelling and drying of the paste material due to the heating effect of dielectric heating can be expected. Then, the double-faced corrugated cardboard sheet 3 after the bonding is completed is the belt 8 and the lower belt 1.
It is sandwiched by 1 and guided to enter the cooling part 7, and then sent to the next process.

(Effects of the Invention) As described above in detail, according to the present invention, because of the non-contact method utilizing the static pressure of air instead of the weight roll, a local pressure does not act on the corrugated cardboard sheet, Uniform pressure is obtained, collapse of the step is avoided, and the quality of the sheet can be improved. At the same time, in the present invention, by utilizing the dielectric heating by the grid electrode, it is possible to significantly reduce the heat energy as compared with the conventional indirect heating method, and only the glue portion is selectively heated, so that the heating efficiency is high. Since it is possible to eliminate the factor that hinders the dielectric heating effect by combining with the non-contact pressurization method using the static air pressure, the productivity of the corrugated board sheet can be further enhanced.

Further, since the pressurizing means is pneumatic, it is not necessary to interpose a sheet supporting member between the dielectric heating device and the corrugated cardboard sheet facing the dielectric heating device. It does not affect the heating of the glue and may cause a loss of power. Further, by controlling the air pressure and the flow rate to be supplied to the air ejection device, it is possible to apply the optimum pressing force to the bonding of the corrugated cardboard sheets, and the heating of the glue as in the conventional device depends on the heat conduction. However, since the above-mentioned pressing force can also be reduced as compared with the conventional device, the step collapse is not generated.

[Brief description of drawings]

FIG. 1 is an overall side sectional view of a double facer showing an embodiment of the present invention, and FIGS. 2, 3, and 4 are perspective views showing arrangement examples of different grid electrodes showing the embodiment of the present invention, respectively. Fifth
4 is a condition diagram for determining dimensions in the embodiment shown in FIG. 4, FIG. 6 is a cross-sectional view showing a state of electric field generation in the AA cross section of FIG. 2, and FIG. 7 is a static pressure type air jet. FIG. 8 is a side sectional view when a static pressure pad is used as an example of the apparatus, and FIG. 8 is a side sectional view when a static pressure container is used as an example of the apparatus.
FIG. 9 is an overall side sectional view of a conventional double facer, and FIG.
The figure is a side view showing the occurrence of collapse of the corrugated cardboard sheet. Description of main parts of the figure 1 …… Single-sided corrugated sheet 2 …… Liner 3 …… Double-sided corrugated sheet 15 …… Lattice electrode 16 …… Air ejection device 18 …… Static pressure pad 19 …… Static pressure container

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-58-134734 (JP, A) JP-B-45-17879 (JP, B2) JP-B-39-13747 (JP, B2)

Claims (1)

[Claims] 1. A double facer for producing a double-faced corrugated sheet by attaching a liner to a corrugated core paper of a single-faced corrugated sheet, and providing an appropriate sheet supporting means on the back side of the single-faced corrugated sheet and the surface of the liner. Place the dielectric heating device on the side with an appropriate gap with the liner surface,
A double facer is also provided, which covers the same device and is provided with an air ejection device for generating static pressure by air between the liner and the liner.