JP2008030982A - Method for cooling glass ribbon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the breakage frequency of a glass ribbon, continuously formed by a float method and having thick parts at the both end parts in the width direction and a thin part relatively thinner than the thick parts at the intermediate part between the thick parts, in an annealing furnace by properly cooling the glass ribbon so that the difference between the temperatures of the thick parts and the thin part becomes as small as possible in the annealing furnace. <P>SOLUTION: In the method for cooling the glass ribbon, comprising cooling the glass ribbon 2 in the annealing furnace having a gradually cooling region and a cooling region on the downstream side of the gradually cooling region while transferring the glass ribbon 2 continuously formed by the float method to the downstream side, when the glass ribbon 2 having the thick parts 2a at the both end parts in the width direction and the thin part 2b relatively thinner than the thick parts 2a at the intermediate part between the thick parts 2a is transferred over from the gradually cooling region to the cooling region in the annealing furnace, only the both end parts in the width direction of the glass ribbon 2 are supplementarily cooled only in the cooling area except for the gradually cooling area. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a glass ribbon cooling method in which a glass ribbon that is continuously formed by a float process and conveyed downstream is cooled in a slow cooling furnace.

  As is well known, when manufacturing a glass substrate for a flat panel display (hereinafter, also simply referred to as FPD) such as a liquid crystal display or a plasma display, a method in which a plurality of glass substrates are made from a single glass plate (mother glass). Has been adopted. With the recent increase in the size of FPD glass substrates, the size of mother glass manufactured by glass manufacturers and the like is also being increased.

  As a method of manufacturing a glass plate to be this kind of mother glass, the molten glass is drawn out in the horizontal direction in the same manner as in the case of manufacturing the window glass plate and molded on a float bath in which molten metal such as molten tin is stored. The float process is known. More specifically, according to the float method, when the molten glass is floated on the molten metal of the float bath, it naturally spreads and becomes a stable thickness (hereinafter referred to as equilibrium thickness). A glass ribbon can be formed. Then, the glass ribbon formed in this manner is gradually cooled in a slow cooling furnace, and then the glass ribbon is cut into a predetermined size to produce a glass plate that becomes mother glass.

  By the way, the high-temperature glass ribbon immediately after being molded in the float bath is cooled in the slow cooling furnace as described above and returned to substantially normal temperature. However, if the cooling of the glass ribbon is inappropriate, the inside of the glass ribbon There may be a problem that distortion or the like is generated. Therefore, various measures have been taken for cooling the glass ribbon in this type of slow cooling furnace. Specifically, for example, in Patent Document 1 below, while the glass ribbon (glass strip) is passing through the slow cooling furnace (layer), the temperature at both ends of the glass ribbon is always earlier than the center portion. From the viewpoint of being easy to cool, it has been proposed to cool the glass ribbon by the following method. That is, the inside of the slow cooling furnace is divided into a slow cooling region for slowly cooling the glass ribbon and a cooling region for cooling the glass ribbon from the upstream side to the downstream side. In order to make the temperature difference as small as possible, outside air is additionally introduced into the central part from the cooling zone and gradually cooled, and in the cooling zone, the central part of the glass ribbon is cooled to be lower than both side ends, and a slow cooling furnace In the vicinity of the outlet, a method of cooling both side edges more strongly than the central part of the glass ribbon has been proposed.

  In recent years, as the glass plate becomes thinner, the glass ribbon is usually required to have a thickness smaller than the equilibrium thickness. In this case, generally, a technique is adopted in which a forming device called a top roll is pressed on both ends of the glass ribbon in the width direction, and both ends in the width direction of the glass ribbon are stretched and thinned (for example, Patent Document 2 below). reference). And the glass ribbon formed in this way has thick portions at both ends in the width direction with the place where the top roll is pressed as a boundary, and from the thick portion at the intermediate portion between these thick portions. Will also have a thin portion that is relatively thin. In this case, at the stage of separating the glass plate from the glass ribbon, the thin portion becomes an effective portion of the glass plate, and the thick portion is cut as an ear portion.

Further, in Patent Document 3 below, the thin-walled portion of the glass ribbon carried into the slow cooling furnace protrudes upward from the glass ribbon having the thick-walled portion (ear portion) and the thin-walled portion (center portion) as described above. In order to bend so as to become, a technique for forcibly cooling both thick portions (both ears) of the glass ribbon at a predetermined location between the exit of the float bath and the entrance of the slow cooling furnace is disclosed.
Japanese Patent Publication No.49-47005 Japanese Patent Publication No. 44-23828 JP 2000-72457 A

  By the way, in recent years, as described above, since glass ribbons often have a thick part and a thin part in the width direction as described above, even glass ribbons having such a shape are suitable in a slow cooling furnace. It is essential to perform proper cooling.

  However, when a glass ribbon having a thick part and a thin part in the width direction is cooled in a slow cooling furnace in this way, the thick part of the glass ribbon tends to be less likely to be cooled than the thin part due to the difference in thickness. It is in. This tendency increases as the glass ribbon becomes thinner. This is because as the thickness of the glass ribbon is reduced, the thickness of the thin portion becomes thinner, but on the other hand, the thickness of the thick portion does not change so much. This is because the thickness difference increases. Therefore, the thinner the thickness of the glass ribbon, the larger the temperature difference between the thick part and the thin part.If the glass ribbon is cooled in a slow cooling furnace without taking this temperature difference into account, There is a possibility that the glass ribbon may be damaged in the slow cooling furnace due to internal stress caused by the temperature difference between the meat part and the thin part.

  Therefore, in the glass ribbon having a thickness difference in the width direction as described above, it is important how to correct the temperature difference between the thick part and the thin part in the slow cooling furnace. The fact is that no measures have been taken. That is, the technique disclosed in Patent Document 1 is, as already described, made from the viewpoint that the temperature at both ends of the glass ribbon tends to be cooled more easily than at the center, and both ends in the width direction. It is not intended for glass ribbons that tend to be difficult to cool, in other words, glass ribbons having thick portions at both ends in the width direction and thin portions between these thick portions.

  On the other hand, as disclosed in Patent Document 3, when the thick portion of the glass ribbon is forcibly cooled at a predetermined position from the outlet of the float bath to the inlet of the slow cooling furnace, the glass ribbon is in this region. Since the temperature of the glass ribbon exceeds the strain point, when the glass ribbon is cooled so rapidly that the curve is generated, the glass ribbon is distorted. As a result, the glass ribbon breaks in the slow cooling furnace, or the glass ribbon. Fatal problems such as reduced strength and spontaneous destruction of the glass plate separated from the glass can occur.

  The subject of the present invention is a thin part which is continuously formed by the float process and has a thick part at both ends in the width direction and is relatively thinner than the thick part at an intermediate part between these thick parts. In the slow cooling furnace, the glass ribbon is appropriately cooled so that the temperature difference between the thick part and the thin part becomes as small as possible, and the frequency of breakage of the glass ribbon in the slow cooling furnace is reduced.

  The present invention devised to solve the above problems is a glass ribbon that is cooled in a slow cooling furnace having a slow cooling region and a cooling region downstream thereof while conveying the glass ribbon continuously formed by the float process to the downstream side. In the cooling method, a glass ribbon having a thick portion at both end portions in the width direction and having a thin portion that is relatively thinner than the thick portion at an intermediate portion between the thick portions is a slow cooling region in the slow cooling furnace. When transporting across the cooling zone, only the both ends in the width direction of the glass ribbon are supplementarily cooled only in the cooling zone excluding the slow cooling zone.

  According to the above method, since only the both ends in the width direction of the glass ribbon are supplementarily cooled in the cooling zone in the slow cooling furnace, the thick portions at the both ends in the width direction are additionally cooled. Therefore, it is possible to properly cool both the thin portion and the thick portion that is less likely to be cooled than the thin portion as much as possible. Usually, in the slow cooling region, the glass ribbon is in a temperature region exceeding the strain point, and in the cooling region, the glass ribbon is in a temperature region below the strain point. Therefore, the supplemental cooling of the both ends in the width direction of the glass ribbon in the cooling zone is started after the temperature of the glass ribbon becomes equal to or lower than the strain point. That is, it is possible to avoid a situation in which the glass ribbon is newly distorted by supplementary cooling of both ends of the glass ribbon. Therefore, by supplementarily cooling only the both ends in the width direction of the glass ribbon in the cooling region in this way, it becomes possible to reduce the breakage frequency of the glass ribbon in the slow cooling furnace as much as possible.

  In the above method, it is preferable that supplementary cooling of both ends in the width direction of the glass ribbon is started after the glass ribbon is cooled to a temperature range from the strain point to −100 ° C. of the strain point. Here, “the glass ribbon is cooled to a temperature range from the strain point to −100 ° C. of the strain point” means that the thick portions at both ends in the width direction of the glass ribbon that are most difficult to cool are the above temperatures. Means cooled to range.

  In this way, the cooling of both ends (thick parts) in the width direction of the glass ribbon is started immediately after the glass ribbon enters the cooling zone or at an early stage. Therefore, the glass ribbon in the slow cooling furnace is used. The probability of occurrence of breakage can be more reliably reduced. In this case, it is more preferable to perform supplementary cooling of both ends in the width direction of the glass ribbon in the cooling region until the temperature difference between the thick part and the thin part becomes 35 ° C. or less.

  In the above method, a supplementary cooling of both ends in the width direction of the glass ribbon is performed directly from the auxiliary cooling means disposed in the cooling zone to the thick wall portions at both ends in the width direction of the glass ribbon. It is preferable to carry out by ejecting.

  In this way, for example, compared to a case where a chamber or the like is disposed in the vicinity of the thick part and the cooling fluid is circulated therein to cool the thick part indirectly, the thick part is cooled. Efficiency can be greatly improved. Therefore, the number of auxiliary cooling means for cooling the thick part can be reduced, and the structure in the slow cooling furnace becomes simple and inexpensive.

  In the above method, the cooling fluid ejected from the auxiliary cooling means is preferably a cooling gas.

  As the cooling fluid, a cooling liquid can also be used. However, when the cooling liquid is simply jetted onto the thick part of the glass ribbon, there is a possibility that the thick part of the glass ribbon is excessively cooled. . Therefore, when the cooling liquid is used, it is preferable to take measures such as spraying the cooling liquid in the form of a mist. In such a case, the structure of the auxiliary cooling means becomes complicated. On the other hand, if the cooling gas is used as the cooling fluid, even if the cooling gas is simply jetted out, the above-mentioned problem can be preferably avoided. It is possible to properly cool the thick part of the.

  In this case, it is preferable to exhaust the cooling gas ejected from the auxiliary cooling means to the outside of the slow cooling furnace.

  In this way, it is possible to suitably avoid a situation in which an airflow is formed in the furnace by the cooling gas ejected from the auxiliary cooling means and the temperature in the furnace fluctuates.

  In the above method, even when the thickness of the thick portion of the glass ribbon is 1.5 times or more the thickness of the thin portion, the glass ribbon can be suitably cooled.

  That is, according to the above method, even when the thickness difference between the thick wall portion and the thin wall portion becomes large as described above, the temperature difference between the thick wall portion and the thin wall portion is made as much as possible in the slow cooling furnace. The frequency of breakage of the glass ribbon in the slow cooling furnace can be greatly reduced.

  In the above method, the glass ribbon can be suitably cooled even when the thickness of the thin portion of the glass ribbon is 3.0 mm or less.

  That is, according to the above method, while appropriately responding to the demand for thinning that has been promoted in recent years to the glass ribbon, while making the temperature difference between the thick part and the thin part as small as possible in the slow cooling furnace, The frequency of breakage of the glass ribbon in the slow cooling furnace can be greatly reduced.

  According to the present invention as described above, in the cooling zone, the thick portion of the glass ribbon that is less likely to be cooled than the thin portion is supplementarily cooled, so that a temperature difference between the thin portion and the thick portion is possible. In addition to being reduced as much as possible, such supplementary cooling is performed only in the cooling zone, so that it is possible to avoid a situation in which new distortion occurs in the glass ribbon. Therefore, the breakage frequency of the glass ribbon in the slow cooling furnace can be reduced as much as possible.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a schematic side view illustrating an example of a glass ribbon manufacturing apparatus according to the present embodiment. As shown in the figure, the manufacturing apparatus 1 has a float bath 3 for forming a glass ribbon 2 and a slow cooling furnace 4 for cooling the glass ribbon 2 formed by the float bath 3.

  Molten metal 5 such as tin is stored in the float bath 3, and a top roll (not shown) is pressed to both ends in the width direction of the glass ribbon 2 formed on the molten metal 5 so that both ends in the width direction are pressed. While being stretched, the glass ribbon 2 is continuously conveyed to the downstream side by the traction force of a plurality of conveying rolls 6 arranged in parallel in the longitudinal direction (flow direction). That is, the glass ribbon 2 is formed by a so-called float method, and has thick portions 2a at both ends in the width direction with a portion pressed by the top roll as a boundary as shown in FIG. In addition, a thin portion 2b that is relatively thinner than the thick portion 2a is provided at an intermediate portion between the thick portions 2a.

  The slow cooling furnace 4 cools the high-temperature glass ribbon 2 carried out through the outlet portion 3a of the float bath 3 called a dross box by passing the inside toward the downstream side. Specifically, the inside of the slow cooling furnace 4 is divided into an upstream side and a downstream side by upper and lower partition walls 7a and 7b, and the upstream side is a slow cooling region 4a and the downstream side is a cooling region 4b. In the former slow cooling region 4a, the high temperature glass ribbon 2 is gradually cooled to a strain point at a slow cooling rate.

  On the other hand, in the latter cooling zone 4b, the glass ribbon 2 cooled to the strain point is cooled at a higher cooling rate than the slow cooling zone 4a. At this time, the thick portion 2a of the glass ribbon 2 tends to be less likely to be cooled than the thin portion 2b due to a difference in thickness from the thin portion 2b. Therefore, in the cooling zone 4b, as shown in FIGS. 1 and 3, auxiliary cooling means 8 is disposed in the vicinity of both ends in the width direction along the flow direction of the glass ribbon 2, and the auxiliary cooling means 8 is arranged. Thus, only the both ends in the width direction of the glass ribbon 2 are supplementarily cooled. In the present embodiment, the auxiliary cooling means 8 is disposed on at least one of the upper and lower sides of the thick portion 2a (upward in the illustrated example), and directly on at least one of the upper surface and the lower surface of the thick portion 2a. The cooling gas is ejected. In this way, in the cooling area 4b, the auxiliary cooling means 8 supplementarily cools the thick part 2a that is less likely to be cooled than the thin part 2b, so the temperature difference between the thin part 2b and the thick part 2a. Can be efficiently reduced. Since the auxiliary cooling means 8 is disposed only in the cooling zone 4b where the glass ribbon 2 has a temperature equal to or lower than the strain point, the auxiliary cooling means 8 newly adds to the glass ribbon 2 by cooling the thick part 2a. It is also possible to avoid a situation in which distortion occurs. Therefore, by supplementarily cooling the thick part 2a of the glass ribbon 2 by the auxiliary cooling means 8, it becomes possible to reduce the probability of the breakage of the glass ribbon 2 in the slow cooling furnace 4 as much as possible. .

  And in order to enjoy such an advantage more reliably, the supplementary cooling of the thick part 2a by the auxiliary cooling means 8 is that the thick part 2a of the glass ribbon 2 is a strain point (the glass ribbon 2 is a cooling region). It is preferable to start after cooling to the temperature range from immediately after entering 4b) to the strain point of −100 ° C. In this way, the cooling of the thick portion 2a of the glass ribbon 2 is started immediately after the glass ribbon 2 enters the cooling zone 4b or at an early stage when it enters the cooling zone 4b. The probability of occurrence of breakage of the glass ribbon 2 inside can be more reliably reduced. Further, it is more preferable that the supplemental cooling of the thick part 2a by the auxiliary cooling means 8 is performed until the temperature difference between the thick part 2a and the thin part 2b becomes 35 ° C. or less. This is because, if the temperature difference between the thick portion 2a and the thin portion 2b is reduced to this numerical range, it can be considered that there is practically no temperature difference in the width direction of the glass ribbon 2.

  As described above, in the cooling region 4b, the cooling method according to the present embodiment in which the thick portion 2a is supplementarily cooled by the auxiliary cooling means 8, particularly, the thickness of the thin portion 2b is 3.0 mm or less, and It is suitable for cooling the glass ribbon 2 in which the thickness of the meat part 2a is 1.5 times or more the thickness of the thin part 2b. That is, the glass ribbon 2 having such a shape has a large thickness difference between the thick portion 2a and the thin portion 2b, tends to increase the temperature difference between them, and is easily damaged because the thin portion 2b is thin. Although there is a tendency, according to the cooling method according to the present embodiment, even for the glass ribbon 2 having such a tendency, the temperature difference between the thick part 2a and the thin part 2b is reduced as much as possible. This is because the frequency of breakage in the slow cooling furnace 4 can be reliably reduced.

  In addition, although oxygen, nitrogen, etc. can be used as a cooling gas ejected from the auxiliary cooling means 8, it is preferable to use outside air (air) also from a viewpoint of simplification of an installation. Further, the cooling of the thick portion 2a by the auxiliary cooling means 8 may be performed intermittently along the flow direction of the glass ribbon 2, or may be performed continuously. Specific examples of the auxiliary cooling means 8 include, for example, a nozzle in which a cooling gas is circulated, in which a plurality of ejection holes are formed, or a slit-shaped ejection port is formed.

  As described above, it is possible to efficiently cool the thick portion 2a by jetting the cooling gas directly from the auxiliary cooling means 8 to the thick portion 2a. In addition, an air flow is formed toward the outlet of the slow cooling furnace 4, which may cause a temperature fluctuation in the furnace. Therefore, in this embodiment, in order to prevent the generation of airflow, the cooling gas ejected from the auxiliary cooling means 8 is discharged from the vicinity of the auxiliary cooling means 8 to the outside of the furnace. Specifically, as shown in FIG. 4, an exhaust port 9 is formed on the side wall of the slow cooling furnace 4 corresponding to the cooling region 4 b, and the cooling gas is discharged to the outside of the furnace through the exhaust port 9. It is effective in preventing the generation of airflow.

  In the above embodiment, the auxiliary cooling means 8 is exemplified as one that is configured to directly eject the cooling gas to the thick portion 2a. However, instead of the cooling gas, for example, a cooling liquid such as water is ejected. You may comprise as follows. Further, the auxiliary cooling means, for example, arranges a chamber at least one directly above or below the thick portion 2a of the glass ribbon 2, and circulates a cooling fluid (preferably outside air) in the chamber, The thick part 2a of the glass ribbon 2 may be configured to be indirectly cooled.

In order to demonstrate the usefulness of the present invention, Examples 1 to 3 adopting the slow cooling method according to the present invention that supplementally cools the thick portion of the glass ribbon in the cooling zone, and the thickness of the glass ribbon in the cooling zone A comparative test for confirming the frequency of breakage of the glass ribbon in the slow cooling furnace was performed in Comparative Example 1 employing a slow cooling method in which the meat part was not cooled supplementarily. Details of the test conditions of Examples 1 to 3 and Comparative Example 1 are as follows. (1) In Example 1, an indirect cooling device was inserted from the side of the slow cooling furnace as auxiliary cooling means, and cooling air with a total flow rate of 1400 Nm ³ / h was flowed to cool the thick portion of the glass ribbon. (2) In Example 2, a cooling device was directly inserted from the side of the slow cooling furnace as auxiliary cooling means, and cooling air with a total flow rate of 1400 Nm ³ / h was jetted to cool the thick portion of the glass ribbon. (3) In the third embodiment, a cooling device is directly inserted from the side of the slow cooling furnace as auxiliary cooling means, and the thick portion is cooled by directly jetting cooling air having a total flow rate of 1400 Nm ³ / h. Of the cooling gas jetted in, 1000 Nm ³ / h was discharged out of the furnace by the exhaust device on the side of the slow cooling furnace. (4) In Comparative Example 1, the glass ribbon was cooled without providing auxiliary cooling means. The results of these comparison tests are shown in Table 1 below.

  The direct cooling device directly ejects cooling air (25 ° C.) from the nozzle to the thick wall portion, and the indirect cooling device is disposed directly above the thick wall portion of the glass ribbon. Cooling air (25 ° C.) is circulated through the chamber. Moreover, in these contrast tests, as a sample, a glass having a thickness of 1.8 mm, a thickness of 2.9 mm, and a width dimension of 4.5 m formed by a float method. A ribbon was used. And the breakage frequency of the glass ribbon in a slow cooling furnace was evaluated by the frequency | count of breakage per 1000 tons of glass ribbon (glass raw material). Furthermore, the temperature difference between the thick part and the thin part of the glass ribbon was calculated by measuring the temperature in the width direction of the glass ribbon at the outlet of the slow cooling furnace with a radiation thermometer at intervals of 500 mm. Further, the temperature fluctuation in the slow cooling furnace was calculated as a difference between the maximum value and the minimum value within 24 hours by a thermocouple disposed in the upper part of the slow cooling furnace.

  As shown in Table 1 above, in Comparative Example 1 in which the glass ribbon was cooled without providing the auxiliary cooling means, the temperature difference between the thin portion and the thick portion of the glass ribbon was 42 ° C. The breakage frequency of the glass ribbon was 127 times / 1000 tons.

  On the other hand, in all of Examples 1 to 3 in which the auxiliary cooling means is disposed, both the temperature difference between the thin portion and the thick portion and the frequency of breakage are suitably reduced as compared with Comparative Example 1. It can be confirmed. More specifically, in Example 1 in which the thick part was cooled by the indirect cooling device, the temperature difference between the thin part and the thick part was 33 ° C., and the breakage frequency was 68 times / 1000 tons. Further, in Examples 2 and 3 in which the thick part was cooled by the direct cooling device, the temperature difference between the thin part and the thick part was 18 ° C., and no breakage was observed in the glass ribbon. That is, in Examples 1 to 3, the temperature difference between the thin portion and the thick portion is smaller than that in Comparative Example 1, and particularly in Examples 2 and 3, the temperature difference is suitably reduced to 18 ° C. For this reason, it is considered that the glass ribbon has a low breakage frequency or a good result that becomes zero.

  Further, in Example 2, the temperature fluctuation in the slow cooling furnace region was 5 ° C. by jetting the cooling air to the thick part, but the cooling air was exhausted in addition to the conditions of Example 2. In Example 3, the temperature variation in the slow cooling region was 2 ° C., and the same results as those obtained when no cooling air was jetted (Comparative Example 1 and Example 1) were obtained. This also confirms that the temperature fluctuation in the slow cooling furnace can be reduced by exhausting the cooling air.

  As described above, it can be confirmed that the cooling method according to the present invention in which the thick portion of the glass ribbon is cooled by the auxiliary cooling means can suitably reduce the breakage of the glass ribbon in the slow cooling furnace. Further, as the cooling method, direct cooling is more preferable than indirect cooling, and in the case of direct cooling, it is more preferable to exhaust the jetted cooling gas.

  The glass ribbon cooling method according to the present invention includes a glass substrate used for production of flat display panels for various image display devices such as liquid crystal displays, plasma displays, electroluminescence displays, field emission displays, various electronic display functional elements, It is suitable to be used in the manufacturing process of a glass plate used as a base material for forming a thin film.

It is a schematic longitudinal cross-sectional view which shows the whole structure of the manufacturing apparatus which concerns on one Embodiment of this invention. It is a schematic longitudinal cross-sectional view which shows an example of the glass ribbon shape | molded by the manufacturing apparatus shown in FIG. It is a schematic perspective view which shows the cooling zone in the slow cooling furnace shown in FIG. It is a schematic longitudinal cross-sectional view which shows the cooling zone in the slow cooling furnace shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Glass ribbon 2a Thick part 2b Thin part 3 Float bath 3a Float bath exit part (Dross box)
4 Slow cooling furnace 4a Slow cooling zone 4b Cooling zone 5 Molten metal 6 Transport rolls 7a, 7b Partition wall 8 Auxiliary cooling means 9 Exhaust port

Claims (7)

In the glass ribbon cooling method of cooling in a slow cooling furnace having a slow cooling region and a downstream cooling region while conveying the glass ribbon continuously formed by the float process to the downstream side,
A glass ribbon having a thick portion at both end portions in the width direction and a thin portion that is relatively thinner than the thick portion at an intermediate portion between the thick portions is changed from the slow cooling region in the slow cooling furnace to the cooling region. A glass ribbon cooling method characterized by supplementally cooling only both ends in the width direction of the glass ribbon only in the cooling zone excluding the slow cooling zone when transported over.   The supplemental cooling of the both ends in the width direction of the glass ribbon is started after the glass ribbon is cooled to a temperature range from the strain point to -100 ° C of the strain point. Cooling method of glass ribbon.   By supplementary cooling of both end portions in the width direction of the glass ribbon, the cooling fluid is directly jetted from the auxiliary cooling means disposed in the cooling zone to the thick portions at both end portions in the width direction of the glass ribbon. The glass ribbon cooling method according to claim 1, wherein the glass ribbon cooling method is performed.   The method for cooling a glass ribbon according to claim 3, wherein the cooling fluid ejected from the auxiliary cooling means is a cooling gas.   The method for cooling a glass ribbon according to claim 4, wherein the cooling gas ejected from the auxiliary cooling means is exhausted outside the slow cooling furnace.   The method for cooling a glass ribbon according to any one of claims 1 to 5, wherein the thickness of the thick portion of the glass ribbon is 1.5 times or more the thickness of the thin portion.   The thickness of the thin part of a glass ribbon is 3.0 mm or less, The cooling method of the glass ribbon in any one of Claims 1-6 characterized by the above-mentioned.

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