JPH058373A - Web drying equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the drying capacity of the dryer of a gravure printing machine. A far-infrared radiation material is provided on a perforated plate 15 at the tip of a plurality of perforated plate type hot air nozzles 10 for blowing hot air onto the web 1 traveling while being guided by guide rollers 6, and hot air is blown onto the web through the perforated plate 15. Along with heating the far infrared radiation material on the surface of the perforated plate with hot air,
The web is configured to be heated by far infrared radiation.
An electric heater may be provided for heating the far-infrared radiation material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying device for drying a running web in a printing machine, a coater or the like.

[0002]

2. Description of the Related Art Conventionally, in a gravure printing machine, as a drying device for drying ink adhered to a printed web, a hot-air type which guides a running web by rollers and blows hot air on the web. Dryers are widely used. In addition, a perforated plate type hot air nozzle configured to blow out hot air from the perforated plate in order to increase the drying efficiency by blowing the hot air is also known (for example, the actual open sho 6).
No. 0-136774, No. 60-136775, No. 60-136767, No. 60-138195
(See the official gazette).

[0003]

However, in such a conventional drying apparatus, even if a porous plate type hot air nozzle is used to enhance the drying efficiency, the drying capacity is limited, and a comparison is made with respect to a solvent type ink. Even if it is possible to perform good drying, there is a problem that satisfactory drying cannot be performed for water-based ink that is difficult to dry. In particular, when using a plastic film as a printing web, since the plastic film does not have hygroscopicity, a large amount of dryness is required, but the film itself cannot easily be heated at high temperature because it is easily stretched. Therefore, the hot air temperature is 60-100
It is limited to about ° C and it is extremely difficult to dry water-based ink. In order to perform the necessary drying on the water-based ink, the running speed of the web may be reduced or the drying device itself may be enlarged. However, this will reduce the production capacity and increase the size and cost of the device. The problem arises.

The present invention has been made in view of the above problems, and is suitable for a web printed with a water-based ink on a plastic film without increasing the size of the apparatus and reducing the running speed of the web. It is an object of the present invention to provide a drying device that enables stable drying.

[0005]

As a result of intensive studies to solve the above problems, the present inventors have found that a far infrared heater is extremely effective in drying water-based ink, and completed the present invention. That is, the present invention is arranged along the traveling path of the web to be dried, a plurality of perforated plate type hot air nozzles for blowing hot air to the web, and a far infrared radiation material provided on the perforated plate surface at the tip of the hot air nozzle. The gist is a drying device for the web.

Here, in the drying device having the above-mentioned structure, it is preferable to further provide an electric heater for heating the far infrared ray emitting material.

The drying device of the present invention is suitable for use in a gravure printing machine, but is not limited to this, and may be used in other types of printing machines, and is not limited to printing machines. It may be used in other machines that handle webs, such as coaters.

[0008]

In the drying device having the above structure, the perforated plate type hot air nozzle blows hot air to the web at a high speed in a large number of spots during running to efficiently heat and dry the web and the ink applied thereto, At the same time, the far-infrared radiation material on the surface of the perforated plate is heated by hot air to radiate far-infrared rays to the web, thereby more rapidly heating the web, ink, and the like. Therefore, the drying ability is improved without increasing the size of the drying device. Here, since far infrared rays have the property of selectively heating the water-based ink, it is particularly effective for drying the water-based ink.

By the way, the far infrared radiation amount of the far infrared radiation material increases as the temperature rises. For this reason, in the configuration in which the far-infrared radiation material is heated only by the hot air blown onto the web, the far-infrared radiation amount decreases when the hot air temperature is low, but by providing an electric heater, the far-infrared radiation material can be heated to a higher temperature. , The far infrared radiation amount can be increased. Thus, when the hot air temperature cannot be made high, such as when a plastic film is used as the web, the electric heater can be used to increase the drying capacity.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention shown in the drawings will be described below. FIG. 1 is a schematic cross-sectional view showing an embodiment in which the present invention is applied to a gravure printing machine. Reference numeral 1 is a web to be heated, 2 is a plate cylinder for printing on the web 1, and 3 is a web 1.
Is a pressing cylinder for pressing the plate cylinder 2 against the plate cylinder 2, 4 is a guide roller for guiding the web 1, and 5 is a drying device. The guide roller 4 is a heat roller having an induction heating coil inside, and can preheat the web 1 before entering the drying device 5.

The drying device 5 comprises a number of guide rollers 6 arranged to support the non-printing side of the running web 1.
And a first drying hood 7 and a second drying hood 8 arranged to cover the traveling path of the web 1, a hot air chamber 9 provided in the second drying hood 8, and the like. The hot air chamber 9 has a large number of perforated plate type hot air nozzles 10 at positions facing the web 1, and the hot air supplied from the hot air supply pipe 11 into the hot air chamber 9 is ejected from the perforated plate 15 at the tip to cause the web 1 to flow. It is designed to be sprayed on. The hot air chamber 9 is provided with a return passage 12 for hot air blown onto the web 1 at an appropriate position. An exhaust pipe 13 is provided on the back surface of the second drying hood 8 to exhaust used hot air. Although illustration is omitted, a hot air supply device is connected to the hot air supply pipe 11 and the exhaust pipe 13 so that the exhaust air from the exhaust pipe 13 is reheated and supplied to the hot air supply pipe 11. Has become.

Each of the perforated plate type hot air nozzles 10 has a perforated plate 15 having a large number of small holes 16 at its tip, as shown in an enlarged view in FIG. The porous plate 15 is composed of a substrate 15a made of a thin metal plate and a far-infrared radiation material 15b provided thereon by coating or the like.
The far-infrared radiation material 15b has a wavelength of 2 to 20 μm.
It is preferable to emit radiation of about m. Specifically,
Far-infrared emitting ceramics such as alumina, mullite and cordierite can be mentioned. The metal substrate 1
Instead of attaching the far infrared radiation material 15b on the surface of 5a, the whole perforated plate 15 may be formed of a far infrared radiation ceramic plate.

Next, the operation of the drying apparatus having the above structure will be described. After the web 1 has been printed by the plate cylinder 2 and the impression cylinder 3,
It enters the drying device 5 through the guide rollers 4 and is guided and guided by the guide rollers 6 therein. At that time, since the guide roller 4 at the entrance of the drying device 5 is a heat roller, the web 1 is preheated by the heat roller. Next, hot air is blown onto the web 1 running in the drying device 5 in a large number of spots at high speed from the porous plate 15 at the tip of the hot air nozzle 10, and the web 1 is efficiently heated and dried. At the same time, the hot air passing through the hot air nozzle 10 heats the far-infrared radiation material on the surface of the perforated plate 15, and the far-infrared radiation material radiates far-infrared rays to the web, and the far-infrared radiation mainly heats the ink applied to the web. To be done. Thus, the web 1 and the ink are efficiently heated and dried. Here, since far infrared rays have an effect of selectively heating the water-based ink, it is extremely effective in drying a web printed with the water-based ink, which is difficult to dry with only hot air.

In the above embodiment, the far-infrared radiation material provided on the porous plate 15 at the tip of the hot air nozzle 10 is used as the hot air nozzle 10
Although it is configured to be heated by the hot air passing through, it is also possible to employ a configuration in which this far infrared radiation material is heated by an electric heater. FIG. 3 shows an embodiment in that case, and an electric heater 17 is provided at a position where it does not interfere with the small hole on the back surface of the perforated plate 15 to heat the perforated plate 15. The electric heater 17 may be provided on the surface of the porous plate 15. In addition, the far-infrared radiation material provided on the porous plate 15 may have an electric heater embedded therein, or the far-infrared radiation material itself may be made conductive.
You may use itself as an electric heater.

The terminals of the electric heater 17 are connected via an explosion-proof type connection terminal so that sparks do not leak outside when energized.
A heating power supply (not shown) equipped with a controller is connected. A temperature sensor (not shown) such as a thermocouple is attached to the surface of any one of the many electric heaters 17 to detect the heater surface temperature. The output of the temperature sensor is input to the control device provided in the heating power source, and the control device controls the electric heater 17 so that the detected heater surface temperature is maintained at a predetermined set temperature. Control energization to. Thereby, one of the many electric heaters 17 is selected as a control target, and all the electric heaters 17 can be controlled by one control device based on the selection. Here, the electric heater to which the temperature sensor is attached has the highest surface temperature with respect to the same electric input among all the electric heaters 17.

The control device for the electric heater further includes a safety device for cutting off the electric power to the electric heater when the temperature detected by the temperature sensor reaches a predetermined maximum allowable temperature. The maximum allowable temperature is a temperature slightly lower than the temperature at which the explosive gas generated by drying the web may ignite. This eliminates the risk of explosion due to the electric heater. The safety device used here is preferably one having safety measures in two stages. That is, when the temperature detected by the temperature sensor reaches a predetermined temperature (eg, 300 ° C) lower than the maximum allowable temperature, an alarm is issued and the power is turned off, and the temperature detected by the temperature sensor is changed to the maximum allowable temperature. (Eg 320 ° C)
It is preferable to have a function of issuing an alarm again and turning off the power at the time when the temperature reaches. If a safety device having such two-step safety measures is used, the surface temperature of the electric heater can be reliably kept below the maximum allowable temperature, which is safe.

A gas concentration sensor (not shown) for detecting the explosive gas concentration in the hoods is provided at an appropriate position in the drying hoods 7, 8. As a mounting position of this gas concentration sensor, a return passage 1 provided in the hot air chamber 9 is provided.
Within 2 is preferable. The output of the gas concentration sensor is input to the control device for the heating power source of the far infrared heater. This control device monitors the gas concentration in the hood by the signal from the gas concentration sensor, and this gas concentration is detected as an explosion. It also has a function of turning off the electric current to the electric heater 17 when the concentration reaches a fear level.

The second drying hood 8 is provided so as to be movable together with the hot air chamber 9 in the illustrated operating position and the retracted position retracted to the right from the illustrated position, and is moved to the second drying hood 8. A drive mechanism 20 such as an air cylinder for performing the operation is connected. This drive mechanism 20
It operates when the electric heater 17 is in an emergency stop or when the printing press is in an emergency stop.

In the drying device 5 having the above structure, the electric heater 17 heats the far infrared radiation material while the web 1 is running,
As a result, a large amount of far infrared rays are radiated to the web 1, and at the same time, the hot air is blown from the perforated plate 15 at the tip of the hot air nozzle 10 into a large number of spots at high speed. Thereby, the web 1 and the ink are efficiently heated and dried. This apparatus is particularly effective when the hot air temperature cannot be raised so much as when the web 1 is a plastic film.

The electric heater 17 for heating the far-infrared radiation material is controlled so that the surface temperature is constant while the web 1 is being dried, and radiates a certain amount of far-infrared radiation. The surface temperature at this time is naturally lower than a predetermined maximum allowable temperature. By the way, although the surface temperature of the electric heater 17 is controlled, the surface temperature of the electric heater 17 may rise for some reason. In that case, the safety device provided in the control device operates to turn off the electric power to the electric heater 17. As a result, the electric heater 17 does not ignite the explosive gas generated by the drying of the ink. Further, during the drying operation, the gas concentration sensor constantly monitors the explosive gas concentration in the dry hood, and when the explosive gas concentration approaches the explosive concentration, the electric heater 17 is deenergized. This further secures safety. Further, as described above, when the electric heater 17 is de-energized due to an abnormal situation or when the printing machine is stopped, the drive mechanism 20 connected to the second drying hood 8 is operated. , The second drying hood 8 is retracted together with the hot air chamber 9 inside. For this reason, cold outside air flows into the periphery of the web, and the temperature of the portion rapidly decreases, so that trouble such as overheating of the web is prevented.

In the embodiment shown in FIG. 3, the surface temperature of one electric heater is measured, and energization to all electric heaters is controlled based on the measured value. Is not limited to this configuration, the many electric heaters used in one drying device are divided into a plurality of blocks,
The control may be performed for each block, or further, each electric heater may be controlled independently. In addition, in the embodiment of FIG. 1, a mechanism for reciprocating the second drying hood 8 is not provided, but the drying machine of FIG. 1 is also emergency-stopped as in the embodiment of FIG. At that time, a mechanism for retracting the second drying hood 8 may be provided.

[0022]

As described above, according to the present invention, a plurality of perforated plate type hot air nozzles for blowing hot air to the web are arranged along the traveling path of the web, and far infrared rays are provided on the surface of the perforated plate at the tip of the hot air nozzle. Since the radiant material is provided, the far-infrared radiating material radiates far-infrared rays to the web during traveling, and the hot air nozzle blows hot air in a spot shape at high speed, so that the web and the ink applied to it, etc. Can be efficiently heated and dried. Moreover, since the far-infrared radiation material is provided at the tip of the hot air nozzle, it is not necessary to enlarge the drying device itself. For this reason,
The drying device of the present invention does not need to be so large as a whole,
It has an effect that the drying ability is enhanced and the web can be dried at a high speed.

If an electric heater for heating the far-infrared radiation material provided at the tip of the hot-air nozzle is provided, the far-infrared radiation material can be heated to a high temperature regardless of the temperature of the hot-air to increase the far-infrared radiation amount. Further, the heating capacity can be further increased, the temperature of the far-infrared radiation material can be raised quickly, the rise time of the apparatus can be shortened, and the production efficiency of the apparatus can be improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

2 is an enlarged cross-sectional view of the tip of a hot air nozzle in the apparatus of FIG.

FIG. 3 is a schematic sectional view showing another embodiment of the present invention.

[Explanation of symbols]

1 Web 2 plate body 3 impression cylinder 4 Guide roller 5 dryer 6 Guide roller 7 first dry food 8 second dry food 9 Hot air chamber 10 hot air nozzles 12 passages 15 Perforated plate 15b Far-infrared radiation material 17 Electric heater

Claims (2)

[Claims] 1. A plurality of perforated plate type hot air nozzles arranged along a running path of a web to be dried and blowing hot air to the web, and a far infrared ray emitting material provided on the surface of the perforated plate at the tip of the hot air nozzles. Web drying equipment. 2. The web drying apparatus according to claim 1, further comprising an electric heater for heating the far infrared ray emitting material.