JP2014005170A - Method of manufacturing glass plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a glass plate stably for a long period without breaking by reducing abrasion of an annealer roller as much as possible.SOLUTION: A method of manufacturing a glass plate includes the processes of: molding a glass ribbon G by a down-draw method; slowly cooling the glass ribbon G while holding the glass ribbon from both the top and reverse by pairs of annealer rollers 21-24 arranged in a plurality of upper and lower stages and also conveying the glass ribbon downward; and cutting the glass ribbon G in a plate width direction at a cutting position while conveying the glass ribbon downward. In the slow cooling process, a peripheral speed of the annealer roller 21 in the top stage is adjusted to be faster than a peripheral speed of the annealer roller 24 in the bottom stage and a descending speed of the glass ribbon G at the cutting position.

Description

  The present invention relates to an improvement in a technique for producing a glass plate by a downdraw method.

  The down draw method is widely used as a method for continuously producing a glass plate. The down draw method includes, for example, an overflow down draw method, a slot down draw method, a redraw down draw method (also simply referred to as a redraw method), and the like.

  Usually, when manufacturing a glass plate by a down draw method, the manufacturing process is divided roughly into a forming process, a slow cooling process, a cooling process, and a cutting process in order from the upper part. In the slow cooling process, the glass plate is transported downward while being sandwiched from both the front and back sides by a pair of annealing rollers arranged in multiple stages at both ends in the width direction of the formed glass plate, and the glass plate is gradually cooled to cause internal distortion. (For example, refer to Patent Documents 1 and 2).

JP 2009-173525 A JP 2010-143800 A

  By the way, in the slow cooling chamber (annealer) which performs a slow cooling process, it is customary to control so that the peripheral speed of all the annealing rollers may become the same speed.

  However, when the peripheral speed of the annealing roller is controlled as described above, the annealing roller is easily worn, and there is a problem that the service life is shortened. In this case, the replacement frequency of the annealing roller is increased. However, when the annealing roller is replaced, the holding force to the glass plate by the replacing annealing roller is temporarily lost, so that the quality of the glass plate is improved. Since it falls temporarily, the problem that the manufacturing efficiency of a glass plate falls inevitably is caused.

  In addition, when the annealing roller is heavily worn, the friction between the annealing roller and the glass plate increases, so that the surface of the glass plate (both ends in the width direction) is scratched at the contact portion with the annealing roller. The glass plate is easily broken. Further, the wear powder of the annealing roller may contaminate the effective surface (the center in the width direction) of the glass plate, which is a factor that hinders stable production of the glass plate, as well as breakage of the glass plate.

  In view of the above circumstances, it is a technical object of the present invention to reduce the wear of the annealing roller as much as possible and to stably manufacture the glass plate over a long period without damaging the glass plate.

  As a result of intensive studies, the inventors of the present application have come to know the following phenomenon. That is, since the glass plate shrinks as the temperature decreases, the descending speed of the glass plate is not constant in the annealing chamber, which is the stage before the glass plate is completely solidified, but on the upper side where the temperature becomes high. It tends to be slightly faster than the lower temperature side. Therefore, if the peripheral speeds of all the annealing rollers are made constant, a difference occurs between the descending speed of the glass plate and the peripheral speed of the annealing rollers, which causes wear of the annealing rollers. In particular, at the position corresponding to the uppermost annealing roller, the glass plate descends at the highest speed, so that the annealing roller is likely to be worn.

  Accordingly, the present invention, which was created to solve the above-described problems, includes a step of forming a glass plate by a downdraw method, and the glass plate is sandwiched from both front and back sides by a pair of annealing rollers arranged in a plurality of upper and lower stages. In the method for producing a glass plate, comprising the step of slowly cooling while being conveyed downward in the state, and the step of cutting in the plate width direction at the cutting position while conveying the glass plate downward, the periphery of the uppermost annealing roller The speed is characterized by being faster than the peripheral speed of the lowermost annealing roller and the descending speed of the glass plate at the cutting position.

  In this way, the circumferential speed of the uppermost annealing roller is relatively increased according to the descending speed of the glass plate in the slow cooling process, so that the wear of the annealing roller is effectively suppressed. Can do. Here, at the cutting position, the glass plate is completely cooled and solidified, which can serve as a reference for the descending speed of the entire glass plate. Therefore, the peripheral speed of the uppermost annealing roller was set faster than the lowering speed of the glass plate at the cutting position.

  In the above method, it is preferable that a peripheral speed of the lowermost annealing roller is equal to or higher than a descending speed of the glass plate at the cutting position.

  That is, when the peripheral speed of the lowermost annealing roller is slower than the lowering speed of the glass plate at the cutting position, the lowermost annealing roller can be resistant to the movement of the glass plate. Not a little wear occurs. Therefore, the peripheral speed of the lowermost annealing roller is preferably equal to or higher than the lowering speed of the glass plate at the cutting position, and the peripheral speeds of all the annealing rollers are equal to or higher than the lowering speed of the glass plate at the cutting position. Is more preferable. In this case, the relationship of (the lowering speed of the glass plate at the cutting position) ≦ (the peripheral speed of the lowermost annealing roller) <(the peripheral speed of the uppermost annealing roller) is established.

  In the above method, it is preferable that the circumferential speed of each annealing roller is gradually increased from the lowermost annealing roller toward the uppermost annealing roller.

  In this way, since the peripheral speed of the annealing roller is adjusted according to the descending speed of the glass plate in the slow cooling process, it is possible to more reliably reduce the wear of the annealing roller.

  In the above method, it is preferable that the ratio of the circumferential speed of the annealing roller having the fastest circumferential speed to the circumferential speed of the annealing roller having the slowest circumferential speed is more than 100% and 105% or less.

  The change in the descending speed of the glass plate is a slight change because it is mainly caused by the shrinkage of the glass plate in the slow cooling step. For this reason, if there is an excessively large difference between the circumferential speed of the annealing roller with the slowest circumferential speed and the circumferential speed of the annealing roller with the fastest circumferential speed, there is a possibility that the change in the descending speed of the glass plate is not suitable. Therefore, it is preferable to set the ratio of the circumferential speed of the annealing roller with the slowest circumferential speed and the circumferential speed of the annealing roller with the fastest circumferential speed within the above numerical range. The ratio of the peripheral speeds of the fastest annealer roller and the slowest annealer roller is more preferably more than 100% and less than 103%, more preferably more than 100% and less than 101%, assuming that the slowest annealer roller is 100%. Most preferred.

  As described above, according to the present invention, since the peripheral speed of the uppermost annealing roller is set relatively high in the slow cooling process, the speed difference between the peripheral speed of the annealing roller and the descending speed of the glass plate is set. And the wear of the annealing roller can be reduced as much as possible. And when the wear of the annealing roller is reduced in this way, it becomes difficult to form scratches on the glass plate, so that the glass plate is difficult to break during the manufacturing process. In addition, since the service life of the annealing roller is prolonged, the deterioration of the quality of the glass plate due to the replacement work can be reduced, and the stable production of the glass plate can be maintained for a long time.

It is sectional drawing which shows the outline | summary of the manufacturing apparatus of the glass plate which concerns on one Embodiment of this invention. It is a perspective view for demonstrating the cutting | disconnection aspect of the glass plate in the cutting chamber of the manufacturing apparatus of the glass plate which concerns on this embodiment. It is a perspective view for demonstrating the cutting | disconnection aspect of the glass plate in the cutting chamber of the manufacturing apparatus of the glass plate which concerns on this embodiment. It is a perspective view for demonstrating the cutting | disconnection aspect of the glass plate in the cutting chamber of the manufacturing apparatus of the glass plate which concerns on this embodiment.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a longitudinal sectional view showing a main part of a manufacturing apparatus for embodying a glass plate manufacturing method according to an embodiment of the present invention. This manufacturing apparatus continuously forms a glass ribbon G by an overflow downdraw method. Of course, the molding method is not limited to the overflow downdraw method, and may be another downdraw method such as a slot downdraw method or a redraw method. The glass plate Ga obtained by cutting the glass ribbon G is used for substrates and covers of various devices such as flat panel displays such as liquid crystal displays, plasma displays, and organic EL displays, solar cells, touch panels, and lighting. The

  Specifically, this manufacturing apparatus is provided with a molding chamber 1, a slow cooling (annealing) chamber 2, a cooling chamber 3, and a cutting chamber 4 in order from above. Each of the chambers 1 to 4 communicates in the vertical direction.

  In the molding chamber 1, the molten glass Gm is supplied to the molded body 11 having a wedge-shaped cross-sectional shape, and the molten glass Gm overflowing from the top of the molded body 11 is fused at the lower end to flow down. A band-shaped glass ribbon G is formed from the glass Gm. Inside the molding chamber 1, both ends in the width direction of the glass ribbon G are sandwiched from the front and back sides by a pair of cooling rollers 12 just below the molded body 11. This cooling roller 12 is for suppressing the shrinkage | contraction of the glass ribbon G in the width direction, and the width direction both ends of the glass ribbon G which contacts the cooling roller 12 are more than the width direction center part (product part). An inflatable portion (ear portion) that is relatively thick is formed.

  In the slow cooling chamber 2, the internal distortion of the glass ribbon G is removed while the glass ribbon G molded in the molding chamber 1 is gradually cooled to a temperature below the strain point. Inside the slow cooling chamber 2, both ends in the width direction of the glass ribbon G are sandwiched from both front and back sides by a pair of annealing rollers 21, 22, 23, 24 arranged in a plurality of stages (four stages in the illustrated example). The Here, since the atmosphere temperature in the slow cooling chamber 2 is a relatively high temperature near the strain point, the annealing rollers 21 to 24 are composed of inorganic rollers having heat resistance. The number of annealing rollers is not particularly limited as long as it is two or more.

  In the cooling chamber 3, the glass ribbon G gradually cooled in the slow cooling chamber 2 is cooled to near room temperature. Inside the cooling chamber 3, both ends in the width direction of the glass ribbon G are sandwiched from both front and back sides by a pair of support rollers 31, 32, 33 arranged in one or more stages (three stages in the illustrated example). . Here, since the atmosphere temperature in the cooling chamber 3 is relatively low, the support rollers 31 to 33 are configured by rubber rollers (for example, a silicon roller, a neoprene roller, or the like). The support rollers 31 to 33 may be omitted when the plate width of the glass ribbon G is small. When the support rollers 31 to 33 are provided, the subsequent lowering speed of the glass ribbon G (including the lowering speed of the glass plate at the cutting position) substantially matches the peripheral speed of the support rollers 31 to 33. In other words, the support rollers 31 to 33 are hardly worn, and the gripping force for the glass ribbon G is strong, so that the drawing speed of the glass ribbon G becomes a reference.

  In the cutting chamber 4, as shown in FIG. 2, an engraving means 41 and a separating means 42 are arranged. The engraving unit 41 forms a scribe line X in the plate width direction at a predetermined height position on the surface of the glass ribbon G. The separating means 42 is disposed below the engraving means 41, folds a predetermined region on the lower end side of the glass ribbon G along the scribe line X, and separates it as a glass plate Ga.

  Specifically, the engraving means 41 is in contact with the back surface of the glass ribbon G and has a surface plate 43 that is long in the plate width direction of the glass ribbon G, and the glass ribbon G while pressing the glass ribbon G against the surface plate 43. And a scribe cutter 44 for forming a scribe line X on the surface of G. In the illustrated example, the contact surface 43a of the surface plate 43 is a flat surface, but may be a curved surface corresponding to the curved surface of the glass ribbon G when the glass ribbon G is curved in the plate width direction.

  The surface plate 43 and the scribe cutter 44 are held so as to be movable up and down, and are configured to move downward in synchronization with the movement of the glass ribbon G. That is, by moving the scribe cutter 44 in the plate width direction of the glass ribbon G (arrow A direction in the figure) while lowering the surface plate 43 and the scribe cutter 44 at the same speed as the lowering speed of the glass ribbon G, A scribe line X is formed on the surface of the glass ribbon G. The platen 43 and the scribe cutter 44 are lifted away from the glass ribbon G after the operation of forming the scribe line X is finished, and return to a preset initial position. In the illustrated example, when the scribe line X is formed, both ends in the width direction of the glass ribbon G are supported by the support means 46 of the separation means 42. Of course, after the scribe line X is formed, both ends in the width direction of the glass ribbon G may be supported by the support means 46.

  On the other hand, as shown in FIGS. 2 and 3, the separating means 42 includes a fulcrum member 45 that is in contact with the back side (surface) of the glass ribbon G on which the scribe line X is formed, and a lower part than the fulcrum member 45. And supporting means 46 for supporting the glass ribbon G or the glass plate Ga. After the scribe line X is formed on the glass ribbon G, the fulcrum member 45 is replaced with the surface plate 43 so that the lower end edge 45b of the glass ribbon G matches the position where the scribe line X is formed. It abuts along the plate width direction. Further, the contact surface 45 a of the fulcrum member 45 is a flat surface or a curved surface, like the contact surface 43 a of the surface plate 43. Moreover, the support means 46 is arrange | positioned at the width direction both ends of the glass ribbon G thru | or the glass plate Ga, respectively, and when separating the glass plate Ga from the glass ribbon G, it shows by the arrow B in FIG. The glass plate G is rotated in a direction, and a splitting force is applied to the glass ribbon G from the surface on which the scribe line X is formed toward the back side thereof, so that the glass plate Ga is cut and separated. Note that the lower end edge 45b of the contact surface 45a of the fulcrum member 45 does not necessarily coincide with the scribe line X of the glass ribbon G, and may be positioned above the scribe line X. Further, the fulcrum member 45 may be omitted, and the folding force may be applied to the glass ribbon G only by the turning operation by the support means 46.

  The fulcrum member 45 and the support means 46 are held so as to be movable up and down, and the descending speed thereof is configured to be the same as the descending speed of the glass ribbon G. That is, by rotating the support member 46 while lowering the fulcrum member 45 and the support means 46 at the same speed as the lowering speed of the glass ribbon G (the lowering speed at the cutting position), the glass ribbon G is removed from the glass plate. Ga is separated. The fulcrum member 45 and the support means 46 are raised and set in advance after being separated from the glass ribbon G or the glass sheet Ga after the separation operation is completed (the support means 46 delivers the glass plate Ga to the transport means). Return to the initial position.

  In addition, as the support means 46, what supports the glass ribbon G from both the front and back sides of the glass ribbon G, and supports the glass ribbon G by vacuum suction from either the front or back surface of the glass ribbon G, etc. Available.

  The glass plate Ga separated from the glass ribbon G is delivered to a transport means (not shown) for transporting the glass plate Ga to a subsequent process while being supported by the support means 46.

  Next, the manufacturing method of the glass plate by the manufacturing apparatus provided with the above structures is demonstrated.

  First, the glass ribbon G is continuously formed in the forming chamber 1 while the molten glass Gm is caused to flow down. Next, while moving the formed glass ribbon G downward, various treatments are sequentially applied by passing through the slow cooling chamber 2, the cooling chamber 3, and the cutting chamber 4 in order, and a glass plate Ga as a final product is manufactured. Is done. In addition, below, the process in the slow cooling chamber 2 is demonstrated in detail.

  In the slow cooling chamber 2, the both ends of the glass ribbon G are clamped by the annealing rollers 21 to 24 arranged in a plurality of stages.

  Here, in the slow cooling chamber 2, the descending speed of the glass ribbon G varies due to shrinkage, and the descending speed of the glass ribbon G on the high temperature side (upper inlet side of the slow cooling chamber 2) It tends to be faster than the descending speed of the glass ribbon G on the lower outlet side of the cold chamber 2.

  Therefore, the peripheral speeds of the annealing rollers 21 to 24 are not all constant in the slow cooling chamber 2, but are changed so as to correspond to fluctuations in the descending speed of the glass ribbon G. That is, the circumferential speed of the uppermost annealing roller 21 is the circumferential speed of the lowermost annealing roller 24 and the circumferential speed of the supporting rollers 31 to 33 (when the supporting rollers are arranged in a plurality of stages and the circumferential speeds are different). Is set faster than the fastest peripheral speed of the support roller. The peripheral speed of the support rollers 31 to 33 is substantially the same as the descending speed of the glass ribbon G at the cutting position of the cutting chamber 4.

  Specifically, in this embodiment, the circumferential speed of the lowermost annealing roller 24 is set higher than the circumferential speed of the support rollers 31 to 33. Further, the circumferential speed of each of the annealing rollers 21 to 24 is set to gradually increase from the lowermost annealing roller 24 toward the uppermost annealing roller 21. The difference between the peripheral speeds of the annealing rollers 21 to 24 is A / B when the peripheral speed of the annealing roller having the fastest peripheral speed is A and the peripheral speed of the annealing roller having the slowest peripheral speed is B. Is set to be more than 100% and not more than 105%. In this embodiment, the circumferential speed of the uppermost annealing roller 21 is A, and the circumferential speed of the lowermost annealing roller 24 is B.

  In this way, in the slow cooling chamber 2, the peripheral speed of the uppermost annealing roller 21 is set relatively high, so that the peripheral speed of the annealing rollers 21 to 24 and the descending speed of the glass ribbon G are Thus, the wear of the annealing rollers 21 to 24 can be reduced as much as possible. In other words, it is difficult to completely match the actual lowering speed of the glass ribbon G and the peripheral speeds of the annealing rollers 21 to 24, but the uppermost annealing roller 21 is not required to be completely matched. By making the peripheral speed relatively high, it is possible to suppress the wear speed of the annealing rollers 21 to 24 (particularly, the uppermost annealing roller 21). Further, when the wear of the annealing rollers 21 to 24 is reduced as described above, it becomes difficult to form a scratch on the glass ribbon G, and the breakage of the glass ribbon G (or the glass plate Ga) can be suppressed. In addition, the service life of the annealing rollers 21 to 24 can be extended. Therefore, the quality degradation of the glass plate Ga by the replacement | exchange operation | work 1 of the annealing rollers 21-24 can be reduced, and the stable manufacture of the glass plate Ga can be maintained for a long time.

  In addition, this invention is not limited to the said embodiment, It can implement in a various form. For example, the annealing rollers adjacent in the vertical direction may include ones having the same peripheral speed. Further, the peripheral speed of the lowermost annealing roller may be set slower than the peripheral speed of the support roller. Further, an annealing roller above the lowermost annealing roller, excluding the uppermost annealing roller, may include a roller set at a peripheral speed slower than that of the lowermost annealing roller.

  Further, when the circumferential speed of one annealing roller arbitrarily selected from the annealing rollers is C and the lowering speed of the glass ribbon corresponding to the position of the selected annealing roller is D, (C -D) The peripheral speed of each annealing roller may be adjusted so that / D is in the range of 0% to ± 5%.

  Further, the amount of wear of the annealing roller may be detected, and the peripheral speed of each annealing roller may be adjusted according to the detected amount of wear.

  Various changes were made in the peripheral speed of the annealing roller in the annealing chamber, and changes in the amount of wear and the service life of the annealing roller were tested. The annealing rollers were arranged in four stages (upper and lower four), and the supporting rollers were arranged in only one stage (upper and lower). The test results are shown in Table 1.

  In the table, the first annealing roller, the second annealing roller,... Are displayed in order from the upper annealing roller. The circumferential speed of each annealing roller is displayed as a percentage based on the circumferential speed of the support roller (100%). The amount of wear of the roller was evaluated in three stages: “◯”, “Δ”, and “×”. “◯” indicates that the wear amount is small, “Δ” indicates that the wear amount is large, and “×” indicates that the wear amount is extremely large. The roller service life is assumed to be when the diameter of one of the rollers is reduced by 1% because a difference in wear amount is observed between the rollers arranged vertically.

  According to Table 1, as in Comparative Example 1, when the circumferential speeds of all the annealing rollers up to the first to fourth annealing rollers are matched with the circumferential speed of the support roller, the amount of wear is not so good. The service life was about 150 days. Further, even when the peripheral speeds of the first to fourth annealing rollers are changed as in Comparative Examples 2 to 4, if the peripheral speeds of the first annealing roller and the support roller are the same, they are worn. A situation was observed in which the evaluation of the amount and the service life was further worse than that of Comparative Example 1.

  On the other hand, as in Examples 1 to 3, when the circumferential speed of the first annealing roller is faster than the circumferential speed of the fourth annealing roller and the circumferential speed of the support roller, the amount of wear and the number of service days are reduced. It can be recognized that both the evaluations are improved as compared with Comparative Example 1. In particular, the circumferential speed of the fourth annealing roller is made higher than the circumferential speed of the support roller, and the circumferential speed of each annealing roller gradually increases from the fourth annealing roller toward the first annealing roller. In Example 1 set as described above, a very good result was obtained that the service life was 240 days or more.

DESCRIPTION OF SYMBOLS 1 Molding chamber 11 Molded body 12 Cooling roller 2 Slow cooling chamber 21, 22, 23, 24 Annealer roller 3 Cooling chamber 31, 32, 33 Support roller 4 Cutting chamber 41 Cutting means 42 Separating means 43 Surface plate 44 Scribe cutter 45 Support point member 46 Support means G Glass ribbon Ga Glass plate Gm Molten glass X Scribe wire

Claims (4)

A step of forming a glass plate by a down-draw method, a step of slowly cooling the glass plate while being conveyed from the front and back sides in a state of being sandwiched by a pair of upper and lower annealing rollers arranged in a plurality of stages, and the glass plate In the manufacturing method of the glass plate including the step of cutting in the plate width direction at the cutting position while conveying downward,
A method for producing a glass plate, wherein the circumferential speed of the uppermost annealing roller is faster than the circumferential speed of the lowermost annealing roller and the lowering speed of the glass plate at the cutting position.   The method for producing a glass sheet according to claim 1, wherein a peripheral speed of the lowermost annealing roller is equal to or higher than a descending speed of the glass sheet at the cutting position.   3. The method for producing a glass plate according to claim 1, wherein the circumferential speed of each of the annealing rollers gradually increases from the lowermost annealing roller toward the uppermost annealing roller. 4. .   The ratio of the peripheral speed of the annealing roller having the fastest peripheral speed to the peripheral speed of the annealing roller having the slowest peripheral speed is more than 100% and not more than 105%. The manufacturing method of the glass plate of description.

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