JPH07157322A - Heat treating device for glass plate - Google Patents

Abstract

PURPOSE:To prevent warpage, thermal cracking and self-run of the cracking and improve wind pressure resistant strength by introducing a heated glass plate into a heat treating device and blowing hot wind of a specific temp. to both surfaces to treat this glass plate by heating, then uniformly cooling the glass plate. CONSTITUTION:The glass plate 1 heated to 570 to 660 deg.C in a heating furnace is carried downstream by a transporting means 2 and the hot air of 50 to 400 deg.C through a heater 4 mounted at a fan 3 and blast duct 5 is blown from plural blow ports opened toward the glass plate 1 in the longitudinal direction of blowing means 6 to both surfaces of the glass plate 1 under a wind pressure of 1 to 1000Pa. A part of the hot air from nozzles 7 at the front end is made to escape in another directions to suppress a change of the wind pressure. This wind pressure is measured by a pressure detector 8 disposed at the blowing means 6. The measured value is fed back to a motor driver 10 controlling a motor 9, by which the disturbance in the wind pressure is regulated to -50 to 50Pa and the temp. difference to -50 to 50 deg.C. The glass plate having a central tensile stress of 85 to 200kg/cm<2> and a ratio of surface compressive stress and central tensile stress of 1.5 to 3.0 is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing a heat-treated glass sheet which does not self-propel even when a glass sheet is cracked, has sufficient wind pressure resistance and is not thermally cracked.

[0002]

2. Description of the Related Art In a high-rise building, a thick glass plate having a thickness of about 10 mm to 20 mm is used in order to improve the wind pressure resistance of a window glass plate. When using a glass plate of such a thickness, there is a drawback that the weight is significantly increased, and when a thick heat ray absorbing glass or a colored coated glass plate is used, the risk of thermal cracking becomes particularly high. There are drawbacks.

Although it is possible to use an air-cooled tempered glass plate as a measure for reducing the weight and preventing heat cracking, since the air-cooled tempered glass plate becomes many small pieces when broken, it is air-cooled in a high-rise building. The use of a tempered glass plate is not preferable because there is a risk that fragments of the glass plate will fall down from the windows of a high-rise building when damaged.

For this reason, attempts have been made to prevent self-propagation of cracks by adjusting the degree of strengthening of the glass plate as so-called semi-strengthening. Particularly when the thickness of the glass plate is large, JP-A-59-8628. As disclosed in Japanese Patent Laid-Open No. 2-175624 and Japanese Patent Laid-Open No. 2-175624, the glass plate is cooled when the heated glass plate is cooled so that the cooling rate of the glass plate is lower than the natural cooling in the atmosphere. It has been proposed to blow hot air onto.

That is, when a glass plate is rapidly cooled, a compressive stress is generated on its surface and a tensile stress is generated at its center,
The glass plate becomes tempered glass, but the surface compression stress value of the glass plate is suppressed by slowing the cooling rate,
Semi-tempered glass can be obtained. Especially when the thickness of the glass plate is large, a large surface compressive stress is generated even if it is naturally cooled, so it is proposed to suppress the cooling rate of the glass plate and suppress the surface compressive stress value generated in the glass plate. Is the above publication.

[0006]

The cooling rate of the glass plate described in the above publication is determined by the temperature and wind pressure of the hot air blown onto the glass plate, and the balance between the two determines the stress value generated in the glass plate. It becomes an element. Therefore, in order to cool the glass plate so as to have a predetermined stress value, it is necessary to accurately blow the temperature and the wind pressure of the hot air onto the glass plate.

That is, if there is unevenness in the temperature or pressure of the hot air blown onto the glass plate, the stress generated in the glass plate will vary, and as a result, the glass plate will warp and the like, resulting in (especially 12 mm It has been difficult to mass-produce semi-tempered glass having a large plate thickness (exceeding the above).

An object of the present invention is to produce a heat-treated glass sheet which has sufficient wind pressure resistance as a window glass for a high-rise building and the like, has no thermal cracking, is practically inconvenient, and can be mass-produced. To provide a device.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is 570 ° C. to 66 ° C. in a heating furnace.
Conveying means for conveying the glass plate heated to 0 ° C. downstream from the heating furnace, and 50 ° C. arranged so as to face both sides of the glass plate conveyed downstream of the heating furnace.
In a heat treatment device for a glass plate, which comprises at least a blowing means having a plurality of blowout ports for blowing hot air of 400 ° C. toward a glass plate, and a blower which is in communication with the blowing means and supplies hot air to the blowing means, The blowing means and the blower are connected so that hot air is supplied to the blowing means from a direction perpendicular to the glass plate surface direction and the conveying direction, and the tip of the blowing means is directed toward the glass plate surface. And a nozzle for letting out hot air in a different direction from the above, to provide a heat treatment apparatus for any glass plate.

Further, according to the present invention, the temperature in the heating furnace is 570 ° C.
A conveying means for conveying the glass plate heated to 660 ° C. downstream from the heating furnace, and a glass plate conveyed downstream of the heating furnace are arranged so as to face both sides of the glass plate.
A heat treatment apparatus for a glass sheet, which is provided with at least a blowing unit having a plurality of blowout ports for blowing hot air of 0 ° C. to 400 ° C. toward a glass plate, and a blower communicating with the blowing unit and supplying hot air to the blowing unit. In the above, the blowing means and the blower are communicated so that hot air is supplied to the blowing means from a direction perpendicular to the conveying means, and the side surface of the blowing means is an opening opened parallel to the conveying surface of the glass plate. A heat treatment device for a glass sheet according to any one of claims 1 to 3, wherein a portion is provided.

Furthermore, according to the present invention, 57
A conveying means for conveying a glass plate heated to 0 ° C. to 660 ° C. downstream from the heating furnace and a glass plate conveyed downstream of the heating furnace are arranged so as to face both sides of the glass plate. In a heat treatment apparatus for a glass plate, which comprises at least a blowing means having a plurality of blowout ports for blowing hot air of ℃ to 400 ° C toward a glass plate, and a blower communicating with the blowing means and supplying hot air to the blowing means. The air outlet blows hot air having a wind pressure of 1 Pa to 1000 Pa, and the difference in temperature of the hot air blown out at each air outlet is within a range of −50 ° C. to 50 ° C. Provided is a heat treatment apparatus for a glass plate, which is in the range of 50 Pa to 50 Pa.

Furthermore, according to the present invention, 57
A conveying means for conveying a glass plate heated to 0 ° C. to 660 ° C. downstream from the heating furnace and a glass plate conveyed downstream of the heating furnace are arranged so as to face both sides of the glass plate. At least a blowing means having a plurality of blowout ports for blowing hot air of ℃ to 400 ℃ toward the glass plate, and a blower in communication with the blowing means for supplying hot air to the blowing means, and heated glass The central tensile stress σ _t of the glass plate is 85-85 by blowing hot air onto the plate.
In the range of 200 kg / cm ^2, and the ratio σ _c / σ _t and the surface compressive stress sigma _c and the central tensile stress sigma _t is 1.
In the apparatus for heat-treating a glass plate in the range of 5 to 3.0, the blower blows hot air having a wind pressure of 1 Pa to 1000 Pa, and the difference in temperature of the hot air blown out from each blower is in the range of -50 ° C to 50 ° C. The present invention provides a heat treatment apparatus for a glass sheet, characterized in that the bleeding of the air pressure during the blowing of hot air is within the range of -50 Pa to 50 Pa.

In addition, the present invention provides a heat treatment device for a glass plate, wherein the outer periphery of the spraying means is covered with a heat insulating material,
It is intended to provide a glass plate heat treatment apparatus in which a heater is arranged near the outer periphery of a spraying unit, and a glass plate heat treatment apparatus in which a heater is interposed between the spraying unit and the glass plate.

[0014]

When the temperature of the hot air blown toward the glass plate differs depending on the part of the blowing means, the cooling rate of the glass plate is different, and the glass plate after heat treatment may be warped or the glass plate may be corrugated. Inconvenience will occur. The temperature of the hot air blown from each of the blowers in the present invention has a difference in the range of −50 ° C. to 50 ° C. at each of the blowers, and only the wind pressure during the blowing of the hot air is −50 Pa.
Since it is in the range of up to 50 Pa, a stable temperature distribution of the glass plate can be obtained, and the glass plate after heat treatment does not warp or the like.

Specifically, since heat is radiated from the surface of the blowing means, the temperature of the hot air becomes lower in the downstream side than in the upstream side where the hot air is supplied to the blowing means.
Therefore, the temperature difference between upstream and downstream can be reduced by increasing the amount of hot air in the blowing means, but the wind pressure of the hot air changes as the amount of hot air increases, and the glass plate is cooled at the desired cooling rate. I couldn't.

Therefore, in the present invention, by providing a nozzle or an opening at the downstream end of the blowing means to which the hot air is supplied, the amount of hot air in the blowing means is increased to reduce the temperature difference between the upstream and downstream sides. Moreover, the wind pressure at that time can also be sprayed toward the glass plate with a stable size.

Further, the outer circumference of the spraying means is covered with a heat insulating material, the heater is arranged in the vicinity of the outer circumference of the spraying means, and the heater is arranged between the spraying means and the glass plate, so that the spraying means is blown out from the nozzle. The difference in temperature due to the location of the hot air is reduced, and the wind pressure at that time can be blown with a stable size.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic cross-sectional view showing an example of the heat treatment apparatus according to the present invention, and FIG. 1B is a front view of a main part as seen from the carrying direction. Downstream of the heating furnace 20, a transporting means 2 comprising a plurality of rollers for horizontally transporting the glass plate 1
Blowing means 6 for blowing hot air to the upper and lower surfaces of the glass plate 1 are disposed above and below the glass plate 1. The spraying means 6 has a tubular shape extending in the glass plate surface direction and perpendicular to the transport direction, and a plurality of sets are arranged in parallel in the transport direction of the glass plate 1.

The blowing means 6 is arranged above and below the conveying means 2 and is in communication with the blower 3 via the blower duct 5. A heater 4 is attached to the blower 3, and hot air of 50 ° C. to 400 ° C. passes through the blower duct 5
It is supplied to the blowing means 6 from the direction of the glass plate surface and the direction perpendicular to the conveying direction. Further, the glass plate 1 is heated and blown with a wind pressure of 1 Pa to 1000 Pa from a plurality of blow ports provided so as to open toward the glass plate 1 in the longitudinal direction of the blowing means 6. Further, the downstream side of the blowing means 6 to which the hot air is supplied, that is, the blowing means 6
A nozzle 7 is attached to the tip of the spraying means 6
Even if the amount of hot air supplied to the glass plate 1 is large (changes), the amount of hot air blown to the glass plate 1 does not increase (the wind pressure does not change) in the longitudinal direction of the blowing means 6. Let it escape horizontally.

As shown in FIG. 1 (b), in order to control the wind pressure and temperature of the hot air in a well-balanced manner so as to give a stress value that gives a better quality product to the glass plate, pressure is applied to the air outlet or blowing means. The detector 8 is provided to measure the wind pressure of the hot air, and the measured value is used as an electric motor 9 including an induction motor of the blower 3, transmission of servo control, and an inverter control motor.
The wind pressure of the hot air can be changed to a predetermined value by feeding back to the electric motor driver 10 for controlling. In addition, when the wind pressure droops during the blowing of the hot air onto the glass plate, the wind pressure can be adjusted by the above feedback information, and the wind pressure droop can be reduced by -50.
It can be kept within the range of Pa to 50 Pa.

In this way, it is possible to reduce variations in the temperature of the hot air blown onto the glass plate from the respective air outlets and the wind pressure during the blowing of the hot air. The amount of heat radiated from the hot air to the blowing means is almost equal to that before increasing the amount of hot air, so
Temperature drop T _{2 of the} hot air blown from the outlet to the glass plate
Let T _{1 be} the temperature drop of the hot air before the nozzle is provided, Q _{1 be} the hot air amount before the nozzle is provided, and Q _{2 be} the hot air amount after the nozzle is provided, T ₂ = T ₁ × (Q ₁ / becomes Q _2), smaller than the temperature drop of the previous hot air to provide a nozzle, thus the heat treatment the glass plate obtained is not generated warping. This is also shown in FIG. 2 which compares the temperature distribution of hot air in the longitudinal direction of the blowing means with and without the nozzle.

FIG. 3 is a front view of a main part of another example of the heat treatment apparatus according to the present invention as viewed from the transport direction. The blowing unit 6 is arranged above and below the conveying unit 2 and communicates with a blower (not shown) via the blow duct 5. A heater 4 is attached to the blower, and hot air of 50 ° C. to 400 ° C. is supplied to the blowing means 6 through a blower duct 5 from a direction perpendicular to the glass plate surface direction. Furthermore, from a plurality of blow ports provided so as to open toward the glass plate 1 in the longitudinal direction of the blowing means 6, 1 Pa to 100
Hot air is blown onto the glass plate 1 with a wind pressure of 0 Pa. Further, an opening 17 is provided on the side surface of the blowing means 6, so that even if the amount of hot air supplied to the blowing means 6 is large, the hot air is blown to the glass plate 1 so that the amount of hot air is not increased. Allow it to escape horizontally in the plate transport direction.

FIG. 4 (a) is a front view of the main part of the heat treatment apparatus of another example according to the present invention as seen from the transport direction.
(B) is an enlarged longitudinal sectional view of a main part of the spraying means (AA).
It is a line sectional view). In this example, the spraying means 6 is provided with neither a nozzle nor an opening. Similar to the above example, the blowing means 6 is arranged above and below the conveying means 2 and is in communication with the blower via the blower duct 5. A heater 4 is attached to the blower, and is supplied as hot air of 50 ° C. to 400 ° C. through a blower duct 5 to a blowing means 6 from a direction perpendicular to the glass plate surface direction, and this hot air is directed toward the glass plate. To be sprayed.

The body portion 61 of the spraying means 6 is provided with a plurality of outlets 62 which are provided so as to open toward the glass plate 1 in the longitudinal direction thereof.
The hot air is blown toward the glass plate 1 with a wind pressure of 1 Pa to 1000 Pa. The outer circumference of the main body 61 is
Since it is covered with the heat insulating material 11, heat radiation from the blowing means 6 is reduced, and the temperature difference between the upstream side and the downstream side of the blowing means 6 to which hot air is supplied can be reduced.

FIG. 5 is an enlarged vertical sectional view of an essential part showing an example of the spraying means in the present invention. The main body 61 of the spraying means 6 is provided with a plurality of air outlets 62 provided so as to open toward the glass plate 1 in the longitudinal direction thereof, and a heater is provided near the outer periphery of the main body 61. 1
2 are arranged, and therefore, the temperature difference between the upstream side and the downstream side of the blowing means 6 to which the hot air is supplied can be reduced.

FIG. 6 is a front view of a main part of another example of the heat treatment apparatus according to the present invention as viewed in the carrying direction. The blowing unit 6 is arranged above and below the conveying unit 2, and the wind supplied from the blower via the blowing duct 5 is blown toward the glass plate. A heater 13 is arranged between the blowing means 6 and the conveying means 2, and the temperature range of the hot air blown onto the glass plate 1 by the heat of the heater 13 is 5
It becomes 0 to 400 ° C.

The heat treatment apparatus for a glass plate in the present invention is
Of course, it is not limited to the above examples. For example, the spraying means with a nozzle shown in FIG. 1 may be provided with a heater in the vicinity of the outer periphery thereof, or may be covered with a heat insulating material on the outer periphery thereof. In such a case, it is possible to further reduce the temperature difference depending on the part of the blowing means, and it is possible to blow hot air onto the glass plate with a stable wind pressure.

The nozzle shown in FIG. 1 is capable of adjusting the wind pressure by its squeezing, and with the driver for the electric motor of the blower or without the driver for the electric fan, the droop of the wind pressure is -50 Pa to 50 Pa.
It can be suppressed to the range of. Similarly, by providing a shutter or the like at the opening in FIG. 3, it is possible to change the wind pressure of the hot air by adjusting the opening degree of this shutter.

The conveying means may be composed of a plurality of rollers as described above, but the present invention is not limited to this. Immediately after the glass plate is heated while being horizontally conveyed by using a gas hearth, and immediately after exiting from the gas hearth outlet, Even after heat treatment of the heated glass plate, or while the glass plate is hung by the hanging hand and heated in the heating furnace, immediately after exiting from the outlet of this heating furnace,
A transporting means which is usually used for heat treatment of a glass plate such as heat treatment of a heated glass plate is used. When the glass plate is hung by the hanging hand and conveyed, it is preferable that the blowing means is arranged on the left and right of the carrying means which is the hanging hand because of the arrangement of the device.

The heater for heating the air from the blower to a predetermined temperature is provided inside the blower or on the side of the blower, blower / heater / blast duct, heater / blower / blast duct Alternatively, the blower / blower duct / heater may be connected in series in this order, and there is no particular limitation as long as the temperature of the hot air blown out can be in the range of 50 ° C to 400 ° C. Furthermore, the heated air in the heating furnace can be drawn into the blower and supplied to the blowing means as hot air, or the air separately heated by combustion gas or the like can be drawn into the blower and supplied to the blowing means as hot air.

As the heater, an electric heater,
For example, a heat source such as a combustion gas obtained by burning a fuel such as gas or petroleum, or a heat source such as steam or a heat medium fluid is introduced into a heat exchanger for heat exchange. The same applies to the heater arranged near the outer periphery of the spraying means or between the conveying means and the spraying means. In this case, the pipe or the heat exchanger into which the heat medium fluid, the combustion gas, etc. are introduced is arranged at a predetermined position.

The hot air in the present invention is controlled so that the temperature difference at each outlet of the blowing means is 50 ° C. or less, but it is preferably 10 ° C. or less by combining the above various means. Further, hot air is blown onto the glass plate at a wind pressure of 1 Pa to 1000 Pa, but a desired stress value can be sufficiently given to the glass plate even at a wind pressure of 100 Pa or less, and the accuracy at that time is 50P.
It is within a, but it is preferable to be sprayed onto the glass plate with an accuracy within 2 Pa.

The blowing means for blowing hot air toward the glass plate is elongated in a direction parallel to the glass plate surface and perpendicular to the conveying direction of the glass plate, as shown in the drawing, and a plurality of them are arranged in parallel. The glass plate may extend in the carrying direction of the glass plate, and the blowing means having substantially the same shape as the glass plate may be provided in one set above and below the carrying means. When the air from the blower is supplied to the blowing means from the horizontal direction, the arrangement of the blowing means as shown in the figure is preferable in view of the arrangement of the device.

Further, the direction of the hot air supplied from the blower toward the blowing means does not have to be exactly the horizontal direction or the vertical direction as in the above example, but the blowing means has a nozzle or an opening. In this case, it is preferable to be along the horizontal direction and the vertical direction to some extent in view of balancing the wind pressure.

A plurality of air outlets of the spraying means are provided on the surface of the spraying means facing the glass plate.
If the hot air is uniformly blown onto the glass plate, its arrangement is not particularly limited.

The surface of the blowing means and the conveying means, and the surface of the stage on which the hot air is blown, which is surrounded by a wall, has a thermal emissivity of 0.1 to 0.1 such as brass and chrome stainless steel.
It is preferable that it is coated with a material of 0.3 or that the blowing means, the conveying means, and the like are formed of these materials because it can help suppress the cooling rate of the glass plate.

[0037]

According to the present invention, the temperature difference of the hot air blown toward the glass plate due to the part of the blowing means is small, and the variation of the wind pressure of the hot air and the bleeding are also-
Since it is contained within the range of 50 Pa to 50 Pa, the glass plate can be cooled uniformly, the glass plate after heat treatment can be prevented from warping, and a flat and semi-tempered glass plate with a good reflected image can be obtained. Obtainable.

That is, in the blowing means according to the present invention, the temperature difference of the hot air blown onto the glass plate at each of the blow openings is within the range of -50 ° C to 50 ° C, and only the pressure during the blowing of the hot air is -50Pa to 50Pa. Within the range, a stable temperature distribution of the glass plate can be obtained, and the glass plate after heat treatment does not warp.

Therefore, when the present invention is used, the wind pressure resistance is practically sufficient, there is no thermal cracking, and even if cracks occur, the cracks do not run by themselves and the heat-treated glass sheet does not break into fine shreds. (For example, the central tensile stress σ _t is in the range of 85 to 200 kg / cm ² , and the ratio of the surface compressive stress σ _c and the central tensile stress σ _t is σ _c / σ.
_t is in the range of 1.5 to 3.0 and the thickness is 8 mm to 19 m
m glass plate) can be provided. Even if this glass plate is broken, there is little risk that some or all of the fragments will fall off the window frame, and it is useful as a glass plate for construction such as buildings and houses. In particular, while a glass plate that is free from the risk of falling fragments of the glass plate is required, the heat-treated glass plate of the present invention is optimal as a building glass plate for windows for high-rise buildings.
In particular, the heat-treated glass plate of the present invention is suitable for a glass plate such as a heat-absorbing glass plate used for a window or a spandrel having a high risk of heat cracking, a colored coated glass plate, and a heat-ray reflecting glass plate. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a heat treatment apparatus according to the present invention (a) and a front view of a main part as seen from a conveying direction thereof (b).

FIG. 2 is a graph showing the temperature distribution of hot air in the longitudinal direction of the blowing means.

FIG. 3 is a front view of essential parts showing an example of the heat treatment apparatus according to the present invention as viewed from the transport direction.

FIG. 4 is a front view of a main part showing an example of the heat treatment apparatus according to the present invention as viewed from the carrying direction (a) and an enlarged vertical sectional view of the main part of its spraying means (b).

FIG. 5 is an enlarged vertical sectional view of an essential part showing an example of a spraying device according to the present invention.

FIG. 6 is a front view of essential parts showing an example of the heat treatment apparatus according to the present invention as viewed from the transport direction.

[Explanation of symbols]

 1: Glass plate 2: Conveying means 3: Blower 4: Heater 5: Blower duct 6: Blowing means 7: Nozzle 8: Pressure detector 9: Electric motor 10: Electric motor driver 11: Heat insulating material 12, 13: Heater 17: Opening Part 61: Main body part 62: Blow-off mouth

Claims (7)

[Claims] 1. Conveying means for conveying a glass plate heated to 570 ° C. to 660 ° C. in a heating furnace toward the downstream side of the heating furnace, and both sides of the glass plate conveyed to the downstream side of the heating furnace. And a blower having a plurality of blowout ports that blow hot air of 50 ° C. to 400 ° C. toward the glass plate, and a blower that communicates with the blower and supplies hot air to the blower. In the heat treatment apparatus for a glass plate comprising at least, the blowing means and the blower are connected so that hot air is supplied to the blowing means from the direction perpendicular to the glass plate surface direction and the conveying direction, and the blowing A heat treatment apparatus for a glass sheet, characterized in that a nozzle for letting out hot air in a direction different from the direction toward the glass sheet surface is provided at the tip of the means. 2. Conveying means for conveying a glass sheet heated to 570 ° C. to 660 ° C. in a heating furnace downstream from the heating furnace, and both sides of the glass sheet conveyed downstream of the heating furnace. And a blower having a plurality of blowout ports that blow hot air of 50 ° C. to 400 ° C. toward the glass plate, and a blower that communicates with the blower and supplies hot air to the blower. In the glass plate heat treatment apparatus comprising at least, the blowing means and the blower are communicated so that hot air is supplied to the blowing means from a direction perpendicular to the conveying means, and the side surface of the blowing means is a glass plate. 2. An apparatus for heat treating a glass plate, wherein the glass plate is provided with an opening that is opened in parallel with the transport surface of the glass plate. 3. Conveying means for conveying a glass sheet heated to 570 ° C. to 660 ° C. in a heating furnace toward the downstream side of the heating furnace, and both sides of the glass sheet conveyed to the downstream side of the heating furnace. And a blower having a plurality of blowout ports that blow hot air of 50 ° C. to 400 ° C. toward the glass plate, and a blower that communicates with the blower and supplies hot air to the blower. In the heat treatment apparatus for a glass plate, the blower outlet has a wind pressure of 1
Hot air of Pa to 1000 Pa is blown out, and the difference in temperature of the hot air blown out from each of the outlets is within the range of −50 ° C. to 50 ° C., and only the wind pressure droops during blowing of the hot air −5.
A heat treatment apparatus for a glass plate, which is in a range of 0 Pa to 50 Pa. 4. Conveying means for conveying a glass plate heated to 570 ° C. to 660 ° C. in a heating furnace downstream from the heating furnace, and both sides of the glass plate conveyed downstream of the heating furnace. And a blowing unit having a plurality of blowing ports that blow hot air of 50 ° C. to 400 ° C. toward the glass plate, and a blower that communicates with the blowing unit and supplies hot air to the blowing unit. At least, the heated glass plate is blown with hot air, the central tensile stress σ _t of the glass plate is in the range of 85 to 200 kg / cm ² , and the surface compressive stress σ _c and the central tensile stress are in the apparatus the ratio σ _c / σ _t and sigma _t is a heat treatment of the glass plate in the range of 1.5 to 3.0, said吹口the wind pressure 1
Hot air of Pa to 1000 Pa is blown out, and the difference in temperature of the hot air blown out from each of the outlets is within the range of −50 ° C. to 50 ° C., and only the wind pressure droops during blowing of the hot air −5.
A heat treatment apparatus for a glass plate, which is in a range of 0 Pa to 50 Pa. 5. The heat treatment apparatus for a glass plate according to claim 1, wherein the blowing means has an outer periphery covered with a heat insulating material. 6. The heat treatment apparatus for a glass plate according to claim 1, wherein a heater is arranged near the outer periphery of the spraying means. 7. Between the spraying means and the glass plate,
A heater is interposed.
A heat treatment apparatus for glass plate according to any one of 4 above.