JPH0222318B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat treatment furnace suitable for use in heat treatment of glass products such as cathode ray tubes, and particularly relates to a heat treatment furnace that can reduce fuel costs. .

[Prior Art] Conventionally, as this type of heat treatment furnace, there is, for example, a radiant tube type heat treatment furnace. This heat treatment furnace has a plurality of radiant tubes arranged inside the furnace body along the furnace wall, and is equipped with a fan for stirring the atmosphere inside the furnace.
The furnace is configured to burn gas in the radiant tube to raise the furnace atmosphere temperature, thereby heating the product inside the furnace, and to gradually lower the furnace atmosphere temperature to gradually cool the product.

By the way, when a glass product is heated in such a heat treatment furnace, the front side of the glass material exposed to the atmosphere in the furnace is first heated, and the thermal energy is transmitted to the back side, raising the temperature of the entire product. Furthermore, when slowly cooling a product, thermal energy is removed from the front side of the glass material, and thermal energy is transferred to the back side of the glass material to the front side, thereby cooling the entire glass material.

[Problems to be Solved by the Invention] However, when heat treating a relatively thick glass material such as a cathode ray tube, there is a temperature difference between the front side and the back side of the glass material as the temperature rises and falls. The product may crack due to the difference in thermal expansion length between them. For this reason, in the above-mentioned heating furnace, the rate of temperature rise and fall of the product must be set extremely slow to prevent a large temperature difference between the front and back sides of the glass material, which reduces the work efficiency of heat treatment. Not only was the heat treatment bad, but the heat treatment required a long time, resulting in relatively high fuel costs.

[Purpose of the Invention] This invention was made in view of the above circumstances, and it is possible to raise and lower the temperature of glass products in a short time, and therefore it is possible to improve the work efficiency of heat treatment. In other words, it is an object of the present invention to provide a heat treatment furnace that can significantly reduce fuel costs.

[Means for Solving the Problems] The heat treatment furnace of the present invention comprises: a far-infrared panel that is placed inside the furnace body at a distance from the furnace wall, and that irradiates far-infrared rays from a surface that is heated and faces inward; A hot air generating means for heating the far infrared panel by supplying hot air to a space between the far infrared panel and the furnace wall, and a hot air flow path for returning the hot air that heated the far infrared panel to the hot air generating means. , the hot air flow path includes an air supply port opening into the space, an air supply duct interposed between the air supply port and the hot air generation means, and the hot air in the space to the hot air generation means. It is configured to include an exhaust port for discharging the air.

[Function] When heating a glass product in a heat treatment furnace with the above configuration, high-temperature far-infrared rays are irradiated from a far-infrared panel, and when this passes through the glass material, the thermal energy of the far-infrared rays is released into the inside of the glass material. Therefore, the glass material is heated evenly from the front side to the back side. In addition, when slowly cooling glass products, far infrared rays at a temperature lower than the product temperature are irradiated from a far infrared panel, and when this passes through the glass material, it absorbs the thermal energy inside the glass material. Cooling is uniform from the front side to the back side. Therefore, even if the temperature of the product is raised or lowered in a short period of time, there will be no temperature difference in the glass material, and no cracks will occur in the product.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. FIG. 1 is a sectional view showing a heat treatment furnace of an example. The heat treatment furnace shown in this figure is
It heats the inside of the cathode ray tube when it is evacuated and evaporates impurities such as paste attached to solder from the electronic equipment housed inside. By configuring a plurality of cold regions in succession, it is possible to continuously heat treat a plurality of transported cathode ray tubes.

In the figure, numeral 1 is the furnace main body. Furnace body 1
It has a cylindrical shape and is composed of a hearth 2, side walls 3, and a ceiling wall 4. The hearth 2 is made of a refractory material such as refractory bricks, and has an opening 2a extending in the depth direction of the furnace body 1 (in the direction of arrow A in the figure) at its center. The cathode ray tube has its head positioned inside the furnace body 1, and its tail is supported by a conveyance mechanism (not shown) provided under the hearth 2 and is conveyed in the direction of arrow A. It's getting old. The side walls 3 and the ceiling wall 4 are constructed by fixing a heat insulating material such as ceramics to the surface facing the inside of the furnace of an iron plate serving as the outer shell of the furnace body 1, and a plurality of air supply ports 5 are provided on those surfaces.
... and an exhaust port 6... are provided.

Further, inside the furnace body 1, a far-infrared panel 7 whose surface is positioned parallel to the ceiling wall 4 is installed at a distance from the ceiling wall 4. The far-infrared panel 7 has a rectangular plate shape, and
It is configured to irradiate far infrared rays from the surface facing the inside of the furnace when heated. Further, the surface of the far-infrared panel 7 is formed in a wavy shape, so that far-infrared rays are directed and irradiated in random directions inside the furnace. Further, inside the furnace body 1, a far-infrared panel 8 similar to the above is attached with its surface positioned parallel to the side wall 3 and spaced apart from the side wall 4.

On the other hand, hot air generating means 9 is provided outside the furnace body 1. Air supply port 9 of this hot air generating means 9
a is connected to air supply ports 5 of the side wall 3 and ceiling wall 4 via a circulation fan 10 and an air supply duct 11, respectively. In addition, the intake port 9b of the hot air generating means 9
is connected to the side wall 3 via the exhaust duct (hot air flow path) 12.
and an exhaust port 6 of the ceiling wall 4, respectively. Note that reference numeral 15 in the figure is an exhaust duct for discharging a portion of the hot air returned to the hot air generating means 9 to the outside.

Next, the operation when heat-treating glass products using the above heat-treating furnace will be explained.

First, hot air is generated by the hot air generating means 9,
Rotate the circulation fan 10. Then, the hot air passes through the air duct 11 and enters the space 13 defined by the ceiling wall 4 and the far-infrared panel 7, as well as the side wall 3 and the far-infrared panels 7 and 8, as shown by the solid arrow in the figure. is supplied to a space 14 defined by
The far infrared panels 7 and 8 are heated. The hot air then flows through the exhaust port 6, as shown by the dashed-dotted arrow in the figure.
... and is returned to the hot air generating means 9 through the exhaust duct 12. In this case, the hot air
30% is discharged outside from exhaust duct 15, 70%
is returned to the hot air generating means 9.

Here, in the heat treatment furnace constituting the heating area, the far-infrared panel 8 is heated by hot air, and far-infrared rays with a wavelength of 5 to 50 microns are irradiated from the surface facing the inside of the furnace. This far-infrared rays pass through the glass material of the product being transported inside the furnace body 1, and at that time, the thermal energy of the far-infrared rays is released into the glass material, so that the glass material is uniformly distributed from the front side to the back side. heated. Then, the heated products are transported and sequentially enter the constant temperature holding area, and after being maintained at a constant temperature, they are transported to the slow cooling area. Next, in the heat treatment furnace constituting the slow cooling area, the temperature of the hot air to be supplied is set lower than the product temperature. Then, far infrared rays having a temperature lower than the product temperature are irradiated from the surfaces of the far infrared panels 7 and 8. This far-infrared rays pass through the glass material of the product and absorb the thermal energy of the product, so that the glass material is uniformly cooled from the front side to the back side.

In the heat treatment furnace, the far infrared panel 7,
Since the glass product is configured to be heated or cooled by the far infrared rays irradiated from 8, the temperature of the product can be raised or lowered in a short time without causing a temperature difference in the glass material. Therefore, the temperature of the product can be raised and lowered in a short time without causing cracks in the product, and the work efficiency of heat treatment can be improved. In addition, since the hot air discharged from the spaces 13 and 14 is reheated by the hot air generating means 9, the amount of heat dissipated from the furnace body 1 to the outside can be reduced, resulting in significant savings in fuel costs. can do.

Although the above embodiment is configured to supply hot air to the spaces 13 and 14 defined by the side wall 3, ceiling wall 4, and far-infrared panels 7 and 8, the present invention is not limited to such a configuration. Instead, for example, a tube is arranged inside the furnace body 1 to blow hot air supplied from the hot air generating means 9 onto the surfaces of the far-infrared panels 7 and 8 facing the inside of the furnace, and the hot air is passed through a circulation fan similar to the above. Alternatively, the hot air may be forcibly returned to the hot air generating means 9. Furthermore, the same effects as described above can be obtained not only in heat treatment of cathode ray tubes but also in heating for strain relief annealing, coating treatment, baking, molding, strengthening, etc. of other glass products.

[Effects of the Invention] As explained above, in the heat treatment furnace of the present invention,
A far-infrared panel is placed inside the furnace body at a distance from the furnace wall, and emits far-infrared rays from a heated surface facing the inside, and hot air is supplied to the space between this far-infrared panel and the furnace wall. a hot air generating means for heating the far-infrared panel with a hot air flow path; The structure includes an air supply duct interposed between the air supply port and the hot air generation means, and an exhaust port for discharging the hot air in the doki space to the hot air generation means. The temperature can be raised and lowered in a short period of time without causing cracks, and the efficiency of heat treatment can be improved. Also,
The structure is such that the hot air heated by the far-infrared panel is returned to the hot air generating means and heated again, so the amount of heat dissipated from the furnace body to the outside can be reduced, resulting in significant savings in fuel costs. Effects such as being able to do this can be obtained.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention,
It is a sectional view showing a heat treatment furnace. 1... Furnace body, 5... Air supply port, 6... Exhaust port,
7... Far infrared panel, 8... Far infrared panel,
9...Hot air generation means, 11...Air supply duct, 12
...exhaust duct, 13, 14...space.

Claims (1)

[Claims] 1 Located inside the furnace body and separated from the furnace wall,
a far-infrared panel that emits far-infrared rays from a surface that is heated and faces inward; a hot-air generating means that supplies hot air to a space between the far-infrared panel and the furnace wall to heat the far-infrared panel; a hot air flow path that returns hot air that has heated the infrared panel to the hot air generation means; the hot air flow path includes an air outlet opening into the space; 1. A heat treatment furnace comprising: an air supply duct interposed in the space; and an exhaust port for discharging hot air in the space to the hot air generating means.