JP4604527B2 - Method for adjusting atmospheric temperature in induction heating furnace, and drying and baking equipment for painted metal strip - Google Patents

Description

  The present invention relates to a method for adjusting the atmospheric temperature in a heating furnace for adjusting the atmospheric temperature of a heating furnace for drying and baking a coated metal band such as a coated steel sheet, and the drying and baking of a coated metal band for performing such drying and baking. Relates to the device.

Painted steel sheets are used in a wide range of fields such as home appliances, building materials, automobiles, etc., and depending on the application, they are used as they are in visible parts, so there is a demand for a good appearance such as a beautiful painted surface. It is getting more and more strict. Such a coated steel sheet is continuously coated by a coating device such as a roll coater, and then dried, baked, and cooled to become a product.
As drying and baking methods, there are generally a heating method using a heating gas and a heating method using induction heating. A heating method by induction heating is frequently used for reasons such as downsizing of equipment, ease of control, and quick response.

FIG. 2 shows an example of equipment that employs a heating method by induction heating.
As shown in FIG. 2, in this equipment, the surface of the steel plate 200 is coated with a roll coater 101 which is a continuous coating device, the coated steel plate 200 is dried and baked in a drying / baking furnace 102, and the coated steel plate 200 is cooled by the cooling device 103. Here, in the drying / baking furnace 102, the coated steel sheet 200 is heated by an induction current with an induction heating device (not shown), and the outside air is ventilated by the air supply fan 104 and the exhaust fan 105.
Patent Document 1 discloses a drying / baking apparatus using induction heating.
JP-A-6-79218

When the induction heating method described above is used, only the steel sheet is heated by the induction current, so only slight convection heat transfer and radiant heat transfer are generated in the drying / baking furnace. Atmospheric temperature and inner wall temperature hardly increase. For this reason, water vapor generated by evaporation of moisture in the paint in the drying and baking process of the coated steel sheet is condensed on the inner wall of the furnace. However, if dew condensation occurs on the inner wall of the furnace, it becomes water droplets and falls on the undried coated steel sheet, causing coating defects.
As a technique for preventing dew condensation on the inner wall of the furnace, Patent Document 1 discloses that in an induction heating type drying / baking apparatus, hot air and hot air are sent into the furnace and the inner wall of the furnace is heated to a temperature higher than the atmospheric temperature in the furnace. As settable, it is disclosed to prevent vaporization from the belt-like coating body and condensation on the inner wall of the evaporated material.

However, even if the technique described in Patent Document 1 is applied, for example, if the output of the induction heating device is increased with an increase in the conveyance speed, the amount of moisture evaporated in the furnace increases, and it is difficult to prevent condensation. If the temperature of hot air / hot air sent into the furnace is always high in order to prevent or prevent this, the temperature of hot air / hot air will be increased unnecessarily when the plate passing speed is slow. Thus, the energy cost for heating the air fed into the furnace is high. Furthermore, when the temperature of the hot air / hot air is set higher than necessary, a coating defect due to intense evaporation of moisture from the coating film called “WAKI” may occur.
The present invention has been made in view of the above problems, and a method for adjusting the atmospheric temperature in a heating furnace, which prevents dew condensation from occurring in a drying / baking furnace (heating furnace), drying of a coated metal strip, and The purpose is to provide a printing device.

Ambient temperature adjusting method of the induction heating furnace according to claim 1, wherein the ambient temperature adjusting method of the induction heating furnace to adjust the ambient temperature of the induction furnace a coated metal strip by Tsuban performing drying and baking of the coating in, and adjusting the ambient temperature of the induction heating furnace based on the dew point temperature of the induction heating furnace.
The atmosphere temperature adjusting method in the induction furnace according to claim 2, wherein, in the ambient temperature adjusting method in the induction furnace according to claim 1, wherein the atmosphere by adjusting the temperature of the vent gas in the induction heating furnace It is characterized by adjusting the temperature.

The method for adjusting the atmospheric temperature in the induction furnace according to claim 3 is the method for adjusting the atmospheric temperature in the furnace according to claim 1 or 2, wherein the atmospheric temperature is increased within a certain range from the dew point temperature. It is characterized by.
The drying and baking device coated metal strip according to claim 4, wherein, in the drying and baking device dry and coated metal strip for performing the baking of the coating of the coated metal strip by Tsuban an induction heating furnace, the induction Induction heating furnace atmosphere temperature detection means for detecting the atmosphere temperature in the heating furnace and dew point temperature detection means for detecting the dew point temperature in the induction heating furnace, and detected by the induction heating furnace atmosphere temperature detection means the ambient temperature and on the basis of the said dew-point temperature of dew point temperature detected by the detecting means, and controlling the induction heating furnace atmosphere temperature control means the ambient temperature of the induction heating furnace.

Further, the coating metal strip drying and baking apparatus according to claim 5 is the coating metal strip drying and baking apparatus according to claim 4, wherein the induction heating furnace atmosphere temperature control means is configured to vent the interior of the induction heating furnace. The temperature of the atmosphere is controlled by adjusting the temperature of the gas.
Further, the drying and baking apparatus for a coated metal strip according to claim 6 is the drying and baking apparatus for a coated metal band according to claim 4 or 5, wherein the induction furnace atmosphere temperature control means is constant from the dew point temperature. The atmospheric temperature is increased within the range.

According to the invention of claim 1 or 4, wherein, since the adjusting or controlling the ambient temperature of the induction heating furnace based on the dew point temperature of the induction heating furnace, the generation of reliably dew condensation can be prevented.
According to the invention of claim 2 or 5, the temperature of the aeration gas in the induction heating furnace is adjusted to adjust or control the atmosphere temperature, and the atmosphere temperature in the induction heating furnace is simplified as a configuration. Can be adjusted or controlled.
According to the invention of claim 3 or 6, since the ambient temperature is increased within a certain range from the dew point temperature, it is possible to prevent the occurrence of condensation by using energy without waste.

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
The present embodiment is a facility for applying, drying, baking, and cooling a coated steel sheet to which the present invention is applied (hereinafter referred to as a processing facility for a coated steel sheet). FIG. 1 shows the configuration of a processing facility for coated steel sheets.
The processing equipment for the coated steel sheet is to coat the surface of the steel sheet 200 with the roll coater 1, to dry and bake the coated steel sheet 200 in the drying / baking furnace 2, which is a heating furnace, and to cool the coated steel sheet 200 with the cooling device 3. Cooling. Here, the drying / baking furnace 2 includes an air supply fan 4, an exhaust fan 5, a heat exchanger 6, a control device 7, a flow rate adjustment valve 8, a temperature measurement unit 9, and a dew point measurement unit 10.

In the coated steel sheet processing facility, the outside air is first taken into the heat exchanger 6. The taken-in outside air is heated by heat exchange with steam as a heat medium in the heat exchanger 6. Here, the flow rate of the steam flowing into the heat exchanger 6 is adjusted by the flow rate adjusting valve 8 controlled by the control device 7. Thus, the temperature of the outside air can be increased by a predetermined amount by adjusting the flow rate of the steam. The control of the flow rate adjustment valve 8 by the control device 7 will be described later.
The outside air whose temperature has been raised by the heat exchanger 6 (hereinafter referred to as aeration gas) is supplied into the drying / baking furnace 2 by the air supply fan 4.

A coated steel plate 200 from the roll coater 1 is passed through the drying / baking furnace 2. The drying / baking furnace 2 includes an induction heating device (not shown) for heating the coated steel plate 200 by an induction current. The induction heating device dries and bake the coated steel plate 200 that is passed through. At this time, the temperature in the drying / baking furnace 2 (specifically, the furnace atmosphere temperature) and the dew point are measured by the temperature measuring unit 9 and the dew point measuring unit 10.
The temperature measuring unit 9 and the dew point measuring unit 10 respectively output the measured furnace temperature and dew point temperature to the control device 7. Here, the dew point measuring unit 9 measures the dew point temperature based on, for example, information in the drying / baking furnace 2, for example, water vapor pressure.
In general, the dew point temperature is a temperature at which air becomes saturated when cooled at a constant atmospheric pressure without adding moisture.

In the control device 7, the flow rate adjusting valve 8 is adjusted based on the furnace temperature and the dew point temperature, and the flow rate of the steam fed into the heat exchanger 6 is controlled. Thereby, the temperature of the outside gas sent into the drying / baking furnace 2 from the heat exchanger 6 through the air supply fan 4 is adjusted.
The coated steel sheet 200 dried and baked in the drying / baking furnace 2 is then cooled by the cooling device 3. Further, the aeration gas supplied to the drying / baking furnace 2 is ventilated in the drying / baking furnace 2, for example, is vented in the same direction as the passing direction of the coated steel plate 200, and is dried / baked by the exhaust fan 5. It is discharged out of the furnace 2.

Next, adjustment of the flow rate adjustment valve 8 by the control device 7, that is, control contents of the temperature of the aeration gas will be described.
The control device 7 adjusts (specifically opens and closes) the flow rate adjustment valve 9 so that the in-furnace temperature obtained from the temperature measurement unit 9 becomes larger than the dew point temperature obtained from the dew point measurement unit 10, Control the temperature. At this time, the control device 7 controls the temperature so that the furnace temperature is close to the dew point temperature, that is, within a certain range.

In this way, by controlling the temperature of the aeration gas so that the furnace temperature does not fall below the dew point temperature, condensation in the drying / baking furnace can be prevented. Thereby, the coated steel sheet can be dried and baked in a drying / baking furnace without causing coating defects.
Further, the temperature is controlled so that the furnace temperature is close to the dew point temperature, that is, within a certain range, so that the furnace temperature does not become higher than necessary. Thereby, energy use efficiency can be made high and dew condensation prevention can be realized. Furthermore, since the furnace temperature (atmosphere temperature) does not become too high, dew condensation can be prevented without causing coating defects due to intense evaporation of the coating film during the drying process.

The embodiment of the present invention has been described above. However, the present invention is not limited to being realized as the above-described embodiment.
That is, in the above-described embodiment, the case where the coated metal strip is a coated steel plate has been described, but another metal strip may be used.
In the description of the above-described embodiment, the drying / baking furnace 2 realizes the coating metal strip drying and baking apparatus according to the present invention. That is, the temperature measuring unit 9 realizes an in-furnace atmosphere temperature detecting unit that detects the atmospheric temperature in the heating furnace, and the dew point measuring unit 10 realizes a dew point temperature detecting unit that detects the dew point temperature in the heating furnace. The control device 7 includes a furnace atmosphere temperature control means for controlling the atmosphere temperature in the heating furnace based on the atmosphere temperature detected by the furnace atmosphere temperature detection means and the dew point temperature detected by the dew point temperature detection means. Realized.

It is a figure which shows the structure of the processing equipment of the coated steel plate which is embodiment of this invention. It is a figure which shows the conventional installation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Roll coater 2 Drying / baking furnace 3 Cooling device 4 Air supply fan 5 Exhaust fan 6 Heat exchanger 7 Control device 8 Flow control valve 9 Temperature measurement part 10 Dew point measurement part 200 Steel plate

Claims (6)

The coated metal strip by Tsuban at ambient temperature adjusting method of the induction heating furnace to adjust the ambient temperature of the induction furnace of drying and baking of the paint,
Ambient temperature adjusting method of the induction heating furnace and adjusting the ambient temperature of the induction heating furnace based on the dew point temperature of the induction heating furnace. The method for adjusting the atmospheric temperature in the induction heating furnace according to claim 1, wherein the temperature of the aeration gas in the induction heating furnace is adjusted to adjust the atmospheric temperature. The method for adjusting the atmospheric temperature in an induction heating furnace according to claim 1 or 2, wherein the atmospheric temperature is increased within a certain range from the dew point temperature. In a coating metal strip drying and baking apparatus that passes through the induction heating furnace and performs drying and baking of the coating of the coating metal strip,
Induction heating furnace atmosphere temperature detection means for detecting the atmosphere temperature in the induction heating furnace;
Dew point temperature detecting means for detecting the dew point temperature in the induction heating furnace;
The induction heating furnace atmosphere temperature detecting means on the basis of the dew point temperature of said ambient temperature and said dew point temperature detecting means detects the detected induction heating furnace atmosphere temperature control means for controlling the atmospheric temperature of the induction heating furnace When,
An apparatus for drying and baking a coated metal strip, comprising: The induction heating furnace atmosphere temperature control means, drying and baking device coated metal strip according to claim 4, wherein by adjusting the temperature of the vent gas in the induction heating furnace and controlling the ambient temperature. 6. An apparatus for drying and baking a coated metal strip according to claim 4, wherein said induction heating furnace atmosphere temperature control means raises said atmosphere temperature within a certain range from said dew point temperature.

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