JPH069901B2 - Corrugator - Google Patents

Description

The present invention relates to a corrugator that is a corrugated board manufacturing facility,
In particular, it relates to control of a heating device for adhering a sheet and glue.

[Conventional technology]

In the corrugator line, the glue and the sheet are bonded to each other in two places, a single facer and a double facer. Here, as an example, a double facer is taken as an example. FIG. 6 shows a schematic side sectional view of a conventional double facer.

In the figure, the single-faced corrugated cardboard sheet 1 made of a single facer (not shown) in the previous step is coated with the starch paste 13 by the glue machine 14 on the top of the corrugated core paper and enters the double facer 5. On the other hand, the liner 2 is preheated by the preheater 4 and similarly enters the double facer 5. Single-faced corrugated sheet 1 and liner 2 in a double facer
In the heating part 6, the weight rolls 1 sandwiched between the belt 8 driven by the roll 12 and the heating box 9 and further arranged in line on the back side of the belt 8.
It is pressurized at 0 and transferred. When the single-faced cardboard sheet 1 and the liner 2 pass through the heating part 6, heating of the heating box 9 having high-temperature steam therein causes the attached starch paste to gelatinize, and the single-faced cardboard sheet 1
The corrugated core paper and the liner 2 are bonded to each other to form the double-sided corrugated cardboard sheet 3. The double-faced corrugated cardboard sheet 3 is carried out while being sandwiched between the belt 8 and the lower belt 11 in the subsequent cooling part 7 and sent to the next step.

Here, the conventional double facer has the following problems.

That is, the heating method of the glue portion is mainly heat transfer through the vessel wall of the heating box 9 and the liner 2 which is in contact with the vessel wall, and the efficiency is low due to indirect heating and the heating part becomes long. Furthermore, as shown in FIG. 7, adjustment of load fluctuations such as fluctuations in operating speed is performed by empirically manually tilting the heating box, removing the pressure roll of the heating box, and contact heat transfer. It requires a hardware adjustment, such as control, which causes a large loss of time.

[Problems to be solved by the invention]

As described above, in the conventional heating method, since the glued portion is heated by the heat conduction through the liner, enormous energy is required to raise the temperature of the liner, and the heating length is inevitably long. I can't help it. In addition, the control of the heating capacity against load fluctuations such as an increase in the operating speed of the sheet-to-be-heated is an empirical adjustment by actual work such as inclining the heating box and removing the pressure roll, resulting in a large time loss. . Therefore, it is difficult to flexibly change the heat quantity control according to the load fluctuation with respect to the load fluctuation such as the increase of the operating speed, and the energy loss is large. The present invention is intended to solve the above problems.

[Means for solving problems]

Electrodes for concentrated dielectric heating of the gluing part are placed near the sheet of the corrugated corrugated sheet to be glued which runs in the corrugated line. The load fluctuation is detected by a sensor, etc., and it is fed back to the dielectric heating and oscillating circuit, and the oscillation frequency is kept constant by changing the capacitance of the capacitor incorporated in the dielectric heating oscillating circuit. As a means for solving the problem, the voltage between the electrodes is controlled so that an output according to the load can always be supplied to the heating section.

[Action]

When a high frequency voltage is applied between the electrodes arranged in the vicinity of the sheet, an electric field is generated. The target dielectric is E ² εtanδ
f (ε: relative permittivity, tan δ: dielectric loss coefficient, f: frequency,
Heat is generated in proportion to (E: electric field strength), but the value of ε tan δ peculiar to the dielectric is 20 to 30 times higher in water in the glue and in the paper. Concentrate on the glue part. That is, the temperature of the paper hardly rises, and only the temperature of the glue portion rises rapidly to cause gelation. The electric field strength E is proportional to the interelectrode voltage V. According to the test by the inventors, the adhesive portion is 60 to 60% in the application time of 0.2 to 0.5 sec.
The temperature rises by 80 ° C, but the paper hardly rises. In other words, this method does not heat the target portion to be raised by using heat conduction as in the past, but induces self-heating inside.

Further, with respect to a load change due to an increase in the operating speed of the sheet-specific heating material, the change amount is detected by a sensor, and the change amount of the equivalent capacitor capacity between the electrodes corresponding to the change amount is detected by the high frequency oscillation circuit. The resonance frequency is always kept constant and stable oscillation is performed by adjusting the variable capacitance type capacitor provided inside. In addition, with respect to the absolute amount of the load, the voltage between the electrodes is controlled as a result of the above action, and an input corresponding to the load is always supplied to the heating section.

〔Example〕

An example in which the embodiment of the present invention is applied to a double facer will be described below with reference to FIGS. FIG. 3 shows an example in which the grid electrode 15 as an electrode is tilted with respect to the glue line of the sheet on the horizontal surface parallel to the sheet on the lower surface side of the corrugated board sheet.
A parallel plate electrode can also be used as the electrode, and the electrode installation position, the inclination method, and the like are not particularly limited here.

In addition, when tilted, as shown in FIG.
The size and shape are determined under the condition of P.

Here, L is the width of the corrugated board sheet, P is the pitch interval of the electrodes, and θ is the angle of inclination of the electrodes in the corrugated board sheet width direction.

Next, the dielectric heating by the grid electrode will be described. When a high frequency alternating voltage is applied to the grid electrode 15, electric fields are generated between the respective electrodes as shown in FIG.

Incidentally, FIG. 5 shows a cross section taken along the line AA shown in FIG.

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

Next, load variation detection and output control of the sheet heated object will be described. FIG. 1 shows an overall side sectional view of a double facer in which the above grid electrode is arranged. 17 in FIG.
Reference numerals 19 to 19 denote sensors for detecting load fluctuations associated with increase in operating speed. Here, as an example, 17 is a driving speed detection sensor, 18 is a sheet width detection sensor, and 19 is a sheet adhesion amount detection sensor, but the items to be detected and the number, the type of sensor, etc. are not limited. .

Next, FIG. 2 will be described. FIG. 2 is a conceptual diagram of output control when the present invention is applied. The high-frequency oscillator circuit is composed of a variable capacitor C _o and a fixed capacitor C ₁ , and an equivalent capacitor C ₂ and a fixed coil L when a load such as a sheet or glue passes between the electrodes. The arithmetic circuit K is for associating the electric signal of the detected load fluctuation with the capacitance of the equivalent capacitor C ₂ between the electrodes which changes due to the load fluctuation. In general, the increase / decrease in load and the increase / decrease in capacitance of the capacitor C ₂ are proportional. Next, the capacitor capacity control circuit S ₁ is a circuit for controlling the variable capacitor C _o, which is the main feature of the present invention, with respect to the C ₂ and always obtaining a stable oscillation frequency. Here specifically, accompanied no C _o is reduced to increase the C _2, when C ₂ is decreased conversely has a function of increasing the C _o. This function will be described later. Next, the output control circuit S ₂ is a circuit for supplying an output V required for the absolute load amount when the load changes. Generally, the increase / decrease in load is proportional to the increase / decrease in output. V'denotes an output take-out device.

A specific operation example of the dielectric heating device having the control system as described above is as follows.

First, when the load as described above fluctuates during the traveling of the seat, the fluctuation is taken out as an electric signal by the sensor. Here, the fluctuation amount is replaced by the fluctuation of the capacitance of the equivalent capacitor C ₂ by the arithmetic circuit K.

By the way, the resonance frequency f is In because it represented by, if if the C _o is fixed, accompanied no f decrease to an increase in C _2, is accompanied not f the decrease of C ₂ in the opposite on the increase, the load variation Nitaishitea constant value It cannot be maintained at stable oscillation. Here, a capacitor capacity control circuit S ₁ is provided to eliminate such a problem. That is, constantly stable state built oscillation frequency f decreases the C _o if, also an electrical circuit to increase the C _o Conversely if C ₂ is decreased as the S ₁ to C ₂ to the C _o variable increases It is something to keep.

Note that the output control for the absolute amount of load is performed by taking out the voltage between the electrodes specifically by the output extracting device V'from the relationship between the load amount previously incorporated in the output control circuit S ₂ and the required output, and supplying it to the object to be heated. To do.

As shown above, by incorporating two control circuits, stable oscillation and optimum output control are possible.

In the embodiment, only the application example to the double facer is described, but this control is also applicable to the case where the dielectric heating device is arranged to the single facer, so that it is added.

〔The invention's effect〕

As described above, according to the present invention, the provision of the dielectric heating device enables an efficient heating system, and eliminates the enormous amount of energy conventionally used for raising the temperature of the paper.
Further, the adoption of the above-mentioned control circuit enables stable oscillation and output, which leads to quality improvement.

Further, productivity is improved by reducing the loss time during adjustment for load fluctuations due to an increase in the operating speed of the sheet-to-be-heated object. Further, since any empirical know-how is not required for adjustment, anyone can implement it.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention which is suitable for a double facer, and FIG. 1 is a side sectional view showing the whole structure, and FIG.
FIG. 3 is an oscillator circuit diagram, FIG. 3 is a perspective view showing an array of grid electrodes, FIG. 4 is a plan view of FIG. 3, FIG. 5 is a side sectional view of FIG. 3, and FIG. 6 is a conventional double facer. FIG. 7 is a side sectional view showing the overall structure of FIG. 7, and FIG. 7 is an explanatory view showing the heat supply amount control of FIG. DESCRIPTION OF SYMBOLS 1 ... Single-sided corrugated board sheet, 15 ... Lattice electrode, 17 ... Operating speed detection sensor, 18 ... Sheet width detection sensor, 19
… A glue amount detection sensor.

Claims (1)

[Claims] 1. An apparatus for arranging an electrode in the vicinity of a continuously running strip-shaped corrugated cardboard sheet glued to the top of a step and applying a high frequency voltage to the electrode to heat the sheet, the sheet traveling A speed detection sensor, a sheet width detection sensor, a glue adhesion amount detection sensor, a device for constantly controlling the frequency of the high frequency voltage by electric signals from these sensors, and a voltage of the same high frequency voltage by the electric signal. A corrugator, which is provided with a device for controlling.