JPS637670B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for preventing dew condensation in an induction heating drying oven in a continuous coating line.

``Prior Art'' As shown in FIG. 1, a continuous coating line is equipped with an induction heating type drying oven 2 for drying and baking the coating film of the painted steel plate 1. The painted steel sheet 1 passing through the induction coil 3 is heated by the eddy current flowing through the induction coil 3 to the painted steel sheet 1, thereby drying and baking the paint film.

"Problems to be Solved by the Invention" By the way, some paints use water-soluble solvents and others use organic solvents, but regardless of which paint is applied to the steel plate 1, the above-mentioned induction When drying and baking the coating film using coil 3,
Steam is generated from the paint film.

Since the induction coil 3 is cooled by cooling water circulating inside, the steam condenses on the induction coil 3 and eventually drips onto the surface of the painted steel sheet 1, reducing the product quality of the painted steel sheet 1. There was a risk of damaging the

Also, among the steam condensed on the induction coil 3,
The so-called viscous tar generated by the decomposition of the resin in the paint accumulates over time, and eventually the tar drips and adheres to the surface of the coated steel plate 1, which may significantly impair the product quality of the coated steel plate 1, as well as induce induction. Residual resin adhered to the coil 3 and significantly contaminated the induction coil 3.

This is particularly noticeable in paints using organic solvents.

"Means for Solving the Problems" In order to solve the above-mentioned conventional problems, the present invention provides an arrangement in which the outer periphery of the induction coil is spaced apart from the outer periphery of the induction coil so that at least the surface facing the painted steel plate is Surrounded by a shielding plate made of a breathable porous material, air having a temperature that does not reduce the cooling efficiency of the induction coil is pumped into the gap between the induction coil and the shielding plate, and the air is removed from the breathable porous material. The gist of this invention is to diffuse the vapor generated from the paint film of the painted steel sheet that is being dried and baked by the induction coil, thereby preventing the vapor from adhering to the shielding plate, especially the induction coil.

"Example" Examples of the method of the present invention will be described below with reference to FIGS. 2 to 4.

What is shown in FIG. 2 is a first embodiment of the present invention, in which the outer periphery of the induction coil 3 is connected to a shielding plate made of an air-permeable porous material with a required gap g and through a bushing 4. 5, and a required flow rate of air having a temperature (150 to 250° C.) that does not reduce the cooling efficiency of the induction coil 3 is pumped into the gap g between the shielding plate 5 and the induction coil 3.

Note that the shielding plate 5 includes at least the coated steel plate 1.
The surface facing the part may be made of a breathable porous material, and the other part may be made of a non-ventilated material.

The air being forced into the gap g passes through the shielding plate 5.
The steam emitted from the coating film of the painted steel sheet 1 is diffused to prevent the steam from adhering to the shielding plate 5, especially the induction coil 3.

What is shown in FIG. 3 is a second embodiment of the present invention, and in the first embodiment, the outer periphery of the induction coil 3 was surrounded by a shielding plate 5 along the spiral. In the second embodiment shown in FIG.
They are grouped together and enclosed.

In this case, it goes without saying that the passage w in the painted steel plate 1 must be formed in advance.

What is shown in FIG. 4 is a third embodiment of the present invention, in which the outer periphery of the shielding plate 5 in the first embodiment is provided with a required gap g and through a bushing 4. It is surrounded by a shielding plate 6 made of an air-permeable porous material.

In this case, the internal shielding plate 5 is, for example, at least partially made of a breathable porous material, and the external shielding plate 6
For example, at least the surface facing the coated steel plate 1 may be made of an air-permeable porous material.

In the third embodiment, relatively low-temperature (100 to 150°C) air is pumped into the gap g between the induction coil 3 and the internal shielding plate 5, and the internal shielding plate 5 and the external Air at a relatively high temperature (150 to 250°C) and lower pressure than the low temperature air is pumped into the gap g between the shielding plate 6 and the low temperature air, thereby increasing the cooling efficiency of the induction coil 3. In addition, the high-temperature air blown out from the external shielding plate 6 is intended to prevent the adhesion of steam and to prevent the concentration of the coated steel sheet 1 itself from decreasing.

Note that the outer periphery of the shielding plate 5 in the second embodiment shown in FIG. 3 may be further surrounded by a shielding plate 6 with a required gap g and through the bushing 4.

Next, the induction coil 3 and the shielding plate 5 in the first and second embodiments shown in FIGS. 2 and 3 will be described.
The means for supplying air under pressure into the gap g will be explained with reference to FIG.

The air supply means shown in FIG. 5 is applied to the second embodiment shown in FIG. 3 for convenience of explanation, but in principle it can be applied to the first embodiment shown in FIG. Of course, it can also be applied.

As shown in FIG. 5, steam generated from the coating film of the painted steel sheet 1, which is heated by the induction coil 3 surrounded by the shielding plate 5 in the induction heating type drying oven 2, is recovered from the drying oven 2. The steam is collected into an incinerator 10 via an intake damper 8 and an intake fan 9 in a pipe 7, and is incinerated in this incinerator 10.

The burner 10a of the incinerator 10 is provided with an automatic temperature control valve 11 that detects the temperature inside the incinerator 10 and adjusts the amount of burner fuel supplied.

The high-temperature exhaust gas of the steam incinerated in the incinerator 10 is sent to the heat exchanger 12, and released from the heat exchanger 12 to the outside air.

On the other hand, clean room temperature air is passed from the blower 13 to the heat exchanger 1 through the outlet pipe line 13a of the blower 13.
2, the clean air exchanges heat with the high-temperature exhaust gas, and the air at the required temperature is pumped into the gap g between the induction coil 3 and the shielding plate 5 through the supply pipe line 14, and from the shielding plate 5. to diffuse the steam generated from the coating film of the painted steel plate 1, and
Above all, it prevents vapor from adhering to the induction coil 3.

In addition, a part of the air that is pumped into the gap g between the induction coil 3 and the shielding plate 5 is also supplied into the space between the oven wall 2a and the shielding plate 5, so that the inside of the drying oven 2 is kept warm. Good too.

Further, the air supply flow rate is adjusted by an automatic flow rate adjustment valve 15 provided in the supply pipe line 14.

Next, relatively low temperature and relatively high pressure air is pumped into the gap g between the induction coil 3 and the internal shielding plate 5 in the third embodiment shown in FIG.
A means for supplying relatively high temperature and relatively low pressure air to be pumped into the gap g between the internal shielding plate 5 and the external shielding plate 6 will be explained with reference to FIG.

As shown in FIG. 6, the relatively high temperature and relatively low pressure air pumped into the gap g between the internal shielding plate 5 and the external shielding plate 6 is similar to that shown in FIG. Automatic flow rate adjustment valve 15 for supply line 14
Using heat exchanged air through.

Also, the gap g between the induction coil 3 and the internal shielding plate 5
The relatively low temperature and relatively high pressure air to be pumped into the supply pipe 1 immediately after the outlet of the heat exchanger 12
4, a check valve 17 and a temperature sensor 18 are provided in the branch supply pipe 16, and a branch supply pipe 16 located between the check valve 17 and the temperature sensor 18 is provided with a branch supply pipe 16. , a branched outlet pipe 13b branched from the outlet pipe 13a of the blower 13 is connected, and a flow rate is automatically adjusted in the branched outlet pipe 13b according to the temperature detection signal from the temperature detector 18. Air is used which is a mixture of heat-exchanged air and room temperature air through a supply circuit provided with an automatic flow rate adjustment valve 19 for performing this process.

The air supply means as shown in FIGS.
It is most suitable for the induction heating type drying oven 2.

In other words, it is non-polluting by incinerating the vapor of the paint film using an organic solvent, and the incinerated vapor heats the air to prevent dew condensation in the induction coil by exchanging heat with high-temperature exhaust gas, and/or the pre-treatment process in the continuous coating line. This is because it has two major energy-saving effects: heating the air used in the dryer for treated steel sheets.

"Effects of the Invention" As described above, according to the present invention, when a painted steel plate is dried and baked in an induction heating type drying oven, the steam generated from the coating film can be completely shielded by air. It is possible to prevent steam condensation on the induction coil, and therefore there is no possibility of deterioration in product quality due to vapor condensation dripping onto the painted steel plate surface.

In addition, it is non-polluting by collecting and incinerating the vapor generated from the paint film, and it is also used to heat the air for preventing dew condensation in the induction coil by exchanging heat with the high-temperature exhaust gas of the incinerated vapor, and for use in continuous painting lines. It also has the energy-saving effect of heating the air used in the dryer for pre-treated steel sheets.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing a conventional example of an induction coil in an induction heating type drying oven for painted steel sheets, FIGS. 2 to 4 are explanatory views showing each embodiment of the method of the present invention, and FIGS. FIG. 6 is a block diagram showing an example of each air supply means in the present invention. 1... Painted steel plate, 2... Induction heating drying oven, 2a...
Furnace wall, 3... Induction coil, 5, 6... Shield plate made of breathable porous material, 7... Recovery pipe, 8... Intake damper,
9... Intake fan, 10... Incinerator, 12... Heat exchanger, 13... Air blower, 13a... Outlet pipe line, 13b...
Branch outlet pipe line, 14... Supply pipe line, 15... Automatic flow rate adjustment valve, 16... Branch supply line, 17... Check valve, 18... Temperature detector, 19... Automatic flow rate adjustment valve.

Claims (1)

[Scope of Claims] 1. The outer periphery of the induction coil in the induction heating drying oven is surrounded with a shielding plate made of a porous material with a permeable air permeability, at least on the surface facing the painted steel plate, with a required gap. Induction heating in a continuous painting line, characterized in that air having a temperature that does not reduce the cooling efficiency of the induction coil is pumped into the gap between the shielding plate and the induction coil, and the air is blown out from the permeable porous material. How to prevent condensation in drying ovens. 2 The outer periphery of the induction coil in the induction heating drying oven is surrounded with a shielding plate, at least a part of which is made of an air permeable porous material, with a required gap, and the outer periphery of this shielding plate is further surrounded with a required gap. At least the surface facing the painted steel plate is surrounded by a shielding plate made of an air-permeable porous material, and relatively low-temperature air is pumped into the gap between the induction coil and the internal shielding plate. Continuous coating characterized by pumping air at a relatively high temperature and a pressure lower than the pressure of the low temperature air into the gap between the shielding plate and the external shielding plate, and blowing out the air from the external shielding plate. Method for preventing condensation in induction heating drying ovens in production lines.