Analysis method and inhibition method for bright line defect formation of glass substrate

Abstract

The invention discloses an analysis method and an inhibition method for bright line defect formation of a glass substrate, and belongs to the technical field of glass substrate manufacturing. The analysis method comprises the following steps: acquiring key parameters of a feeding structure, including the shoulder height of a main glass flow transition area, the diameter of a feeding exhaust straight pipe and the liquid level height, setting the liquid level height inevitably formed by nitrogen bubbles, and acquiring the internal vortex height and the liquid level height accidentally formed by the nitrogen bubbles; according to the parameters, abnormal glass layer tearing caused by liquid level imbalance due to nitrogen bubbles is a sufficient condition for forming the bright line defect of the glass substrate, the forming risk of the bright line defect of the glass substrate is analyzed and determined, and a scientific basis is provided for optimizing the liquid level height and preventing defect formation. Meanwhile, based on an analysis method for forming the bright line defect of the glass substrate, a suppression method is provided, and the formation of the bright line defect of the glass substrate is suppressed by accurately controlling the liquid level height of the feeding exhaust straight pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of glass substrate manufacturing, and in particular to an analysis method and a suppression method for bright line defects of a glass substrate. Background Art

[0002] In the manufacturing field of TFT-LCD (Thin Film Transistor Display) flat panel displays, the glass substrates used are generally manufactured by the overflow down-pull method, which supplies the molten glass liquid in the glass melting furnace to the molten overflow down-pull molding device to efficiently produce high-quality glass substrates. With the continuous upgrading of the production line, the size of the glass substrate is increasing, and the lead-out amount has also increased significantly, which has posed a more severe challenge to the quality control in the production process, especially the guarantee of the stability of the glass lead plate. Therefore, effectively controlling the formation of defects in the glass substrate manufacturing process has become the key to improving product quality and production efficiency.

[0003] In the manufacturing process of glass substrates, the stirred and homogenized glass melt is supplied to the overflow trough through the feeding exhaust straight pipe and L-tube, and then diverted to both sides through the overflow weir and fused at the root of the overflow brick, and then pulled downward to form a glass substrate with target specification thickness. However, there are two vortex zones in the feeding exhaust straight pipe and L-tube joint area exposed to the factory atmosphere. The vortex pattern of the vortex zone affects the glass quality of the liquid surface in this area, such as the formation of abnormal glass layer and nitrogen bubble defects. Therefore, the vortex pattern of the vortex zone has an important influence on the stability and quality of the glass liquid surface. The intensity, range and dynamic changes of the vortex are directly related to whether abnormal glass layer and nitrogen bubble will appear on the glass liquid surface. The far and near ends, surface and bonding line of the glass substrate have a corresponding positional relationship with the cross section of the feeding exhaust straight pipe and the L-tube. Using this positional relationship, the defects in the glass vortex zone can be controlled to be introduced into the non-important areas of the glass substrate, such as the far and near end side plates, bonding lines, etc., so as to avoid them appearing in the useful areas of the substrate, especially the surface, thereby preventing the periodic appearance of defects from adversely affecting the molding quality of the glass substrate.

[0004] Bright line is a structural defect in glass substrate that seriously affects the quality of glass substrate. Its width is generally within 50mm, and the thickness is often at the micron level. It will present different light angles under special light angles, which can also be seen visually. The impact of this defect on glass substrate is 100% defective rate, which directly threatens the overall quality of the product. Any unstable operation of normal process operation of the production line, such as furnace pressure fluctuation, pool furnace liquid level fluctuation, replacement of cover bricks + rod washing, lead-out amount or viscosity temperature adjustment, sudden change of ambient airflow, but it does not necessarily trigger bright line defects, unless these unstable inducements suddenly occur violently or cause the liquid level to be low, see Figure 7-8, nitrogen bubbles burst or crack suddenly; the relative equilibrium and stillness of the liquid surface is broken, causing the abnormal glass layer to tear; the comprehensive pressure at the imbalanced liquid surface causes the surrounding gas to be sucked back into the internal vortex and inertially enter the main glass flow; the surrounding abnormal glass is subjected to inward pressure and enters the internal vortex and inertially enters the main glass flow, which will increase the probability of bright line defects. That is, the formation of the abnormal glass layer is related to the diameter of the feeding and exhaust straight pipe structure, the liquid level, and the internal vortex flow state.

[0005] Therefore, for the supply and exhaust straight pipe that has been designed but has structural design defects, how to provide an analysis method and a suppression method for the formation of bright line defects on the glass substrate, and control the generation of bright line defects on the glass substrate based on the supply structure design, has become a technical problem that technical personnel in this field urgently need to overcome. Summary of the invention

[0006] The object of the present invention is to provide an analysis method and a suppression method for the formation of bright line defects on a glass substrate, so as to overcome the bright line problem caused by the structural design defects of the supply and exhaust straight pipes.

[0007] The present invention solves the above technical problems through the following technical solutions: A method for analyzing the formation of bright line defects on a glass substrate comprises the following steps: Obtain parameters related to the feeding structure, including the shoulder height of the main glass flow transition zone and the diameter of the supply and exhaust straight pipe Liquid level ; According to the position relationship between the liquid level of the supply exhaust straight pipe and the main glass flow, set the liquid level height where nitrogen bubbles must be formed ; Based on diameter , Shoulder height , the internal vortex height related to the formation of the heterogeneous glass layer in the supply and exhaust straight pipe is obtained through fluid simulation ; Based on the positional relationship between the internal vortex and the main glass flow, calculate the liquid level height where nitrogen bubbles occasionally form ; Based on the principle of nitrogen bubbles and heterogeneous glass layer formation, according to the liquid level height of the supply and exhaust straight pipe The liquid level that must be formed with nitrogen bubbles , internal vortex height and the liquid level where nitrogen bubbles occasionally form The relationship between them is used to analyze the formation of bright line defects on glass substrates. Among them, nitrogen bubbles causing the liquid level to be unbalanced and leading to the tearing of the abnormal glass layer is a sufficient condition for the formation of bright line defects on glass substrates.

[0008] Furthermore, the liquid level at which nitrogen bubbles must form is set .

[0009] Furthermore, when the diameter , Shoulder height When the following relations are satisfied:

[0010]

[0011] Obtaining Internal Vortex Height Using Flow Simulation , specifically: .

[0012] Furthermore, when When the liquid level of the supply exhaust pipe is too close to the main glass flow, any process fluctuation or other unstable action of the main glass flow will cause nitrogen bubbles to form near the wall of the liquid level of the supply exhaust pipe. The internal vortex coincides with the liquid level of the feed and exhaust straight pipe, making the liquid level of the feed and exhaust straight pipe completely active. The probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to cause the liquid level to be unbalanced and cause the abnormal glass layer to tear. Therefore, no bright line defects on the glass substrate will be formed.

[0013] Furthermore, when Specifically include: Calculate the liquid level when nitrogen bubbles occasionally form , when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable actions in the main glass flow, which may cause occasional nitrogen bubbles to form near the wall of the feed exhaust straight pipe; When the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, the liquid surface of the feeding and exhaust straight pipe is fully active, the probability of forming an abnormal glass layer is 0, and there are no nitrogen bubbles to unbalance the liquid surface and cause the abnormal glass layer to tear. Therefore, no bright line defect of the glass substrate will be formed; however, when When the glass near the liquid surface of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. Therefore, there are nitrogen bubbles that cause the liquid surface to be unbalanced, resulting in the tearing of the abnormal glass layer and the formation of bright line defects on the glass substrate. when When, due to , the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, and after a long period of circulation, an abnormal glass layer will be formed; however, since the liquid level of the feeding and exhaust straight pipe exceeds the liquid level occasionally formed by nitrogen bubbles There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

[0014] Furthermore, when Specifically include: Calculate the liquid level when nitrogen bubbles occasionally form , when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable movements in the main glass flow, which may cause occasional nitrogen bubbles to appear near the wall of the feed exhaust straight pipe. , the internal vortex coincides with the liquid level of the feeding and exhaust straight pipe, making the liquid level of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to unbalance the liquid level and cause the abnormal glass layer to tear, so no bright line defects will be formed on the glass substrate; when When the liquid level in the feed exhaust pipe exceeds the liquid level where nitrogen bubbles occasionally form , there is no nitrogen bubble causing the liquid level to be unbalanced, and, , the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, making the liquid surface of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0, so no bright line defect of the glass substrate will be formed; when When the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. However, the liquid level of the feeding and exhaust straight pipe exceeds the liquid level formed by nitrogen bubbles occasionally. There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

[0015] Furthermore, any process fluctuations or other unstable actions of the main glass flow specifically include: fluctuations in furnace pressure, fluctuations in liquid level in the furnace, replacement of cover bricks and washing rods in the stirring tank, adjustment of the lead-out amount or viscosity-temperature, and sudden changes in ambient airflow.

[0016] A method for inhibiting the formation of bright line defects on a glass substrate, based on the above analysis method for the formation of bright line defects on a glass substrate, when the internal vortex height for: When controlling the liquid level of the supply and exhaust straight pipe ,make , inhibiting the formation of bright line defects on the glass substrate.

[0017] Furthermore, when the diameter =60 mm, shoulder height =47.55 mm, the internal vortex height is obtained through fluid simulation , specifically , control the liquid level of the supply and exhaust straight pipe for: .

[0018] Furthermore, when the diameter =50 mm, shoulder height =76 mm, the internal vortex height is obtained through fluid simulation , specifically , control the liquid level of the supply and exhaust straight pipe for: .

[0019] Compared with the prior art, the positive and progressive effects of the present invention are: The method for analyzing the formation of defects on a glass substrate provided by the present invention obtains key parameters of a feeding structure, including a diameter of a main glass flow transition region of a channel, a shoulder height, and a liquid level height of a feeding exhaust straight pipe, sets a liquid level height that is inevitably formed by nitrogen bubbles, and obtains an internal vortex height and a liquid level height that is occasionally formed by nitrogen bubbles; based on the above parameters, the formation risk of a bright line defect on a glass substrate is analyzed and determined based on the fact that nitrogen bubbles cause liquid level imbalance and lead to tearing of an abnormal glass layer, which is a sufficient condition for the formation of a bright line defect on a glass substrate, thereby providing a scientific basis for optimizing the liquid level and preventing the formation of defects.

[0020] The present invention also provides a method for suppressing the formation of bright line defects on a glass substrate, and establishes a design benchmark for the liquid level for suppressing the generation of bright lines. Based on the analysis method for the formation of bright line defects on a glass substrate, the formation of bright line defects on a glass substrate is suppressed by precisely controlling the liquid level of the supply and exhaust straight pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 A schematic diagram of the overflow system structure for manufacturing a glass substrate; Figure 2 A schematic diagram of an overflow pull-down structure for manufacturing a glass substrate; Figure 3 It is a schematic diagram of the positional relationship between the near and far ends, the surface and the bonding line of the glass substrate and the cross section of the feeding exhaust straight pipe and the cross section of the L pipe; Figure 4 It is a schematic diagram of the internal vortex in the feed exhaust straight pipe; Figure 5 It is a schematic diagram of the feeding structure; Figure 6 is the liquid level where nitrogen bubbles must form , internal vortex height and a schematic diagram of the liquid level height of the supply and exhaust straight pipe; Figure 7 Schematic diagram of the formation mechanism of the heterogeneous glass layer and nitrogen bubbles; Figure 8 Schematic diagram of the mechanism of bright line formation.

[0023] In the figure: 1- overflow brick; 2- overflow trough; 3- glass liquid feeding device; 4- overflow brick root; 5- drainage plate; 6- molded glass substrate; 7- downward pulling direction of glass substrate; -Glass substrate specification width; -Glass substrate guide plate width; ① is the internal vortex; ② is the vortex in the main glass flow area. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0027] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0028] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0029] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings, which are intended to explain the present invention rather than to limit it.

[0031] See also Figure 1 When the glass substrate is manufactured by molten overflow, the molten glass is supplied to the molten glass feeding device 3 in the molten overflow forming device, and overflows along the overflow trough 2 through both sides of the overflow brick 1 to form a glass substrate from below the root 4 of the overflow brick.

[0032] See also Figure 2 The guide plate serves as a molding basis for the glass substrate. During the process of pulling down the glass substrate, the molded glass substrate 5 moves downward along the glass substrate pulling down direction 6 .

[0033] See also Figure 3 The stirred and homogenized glass melt is supplied to the overflow trough through the feeding and exhaust straight pipe and the L pipe, and then diverted to both sides through the overflow weir and fused at the root of the overflow brick, and then pulled downward to form a glass substrate with target thickness. The far and near ends, surface and bonding line of the glass substrate have a corresponding positional relationship with the cross section of the feeding and exhaust straight pipe and the L pipe. By using this positional relationship, defects in the glass vortex zone (abnormal glass, nitrogen bubbles) can be introduced into non-important areas of the glass substrate (such as the far and near end side plates, bonding lines, etc.), avoiding defects from appearing in the useful area of ​​the glass substrate (especially the surface), which affects the molding quality of the glass substrate.

[0034] See also Figure 4 There are two vortex zones in the supply and exhaust straight pipe and L-tube junction area exposed to the factory atmosphere. The vortex pattern in the vortex zone, including the range and intensity, will affect the glass quality of the liquid surface in this area, resulting in the formation of vortex abnormal glass layer and nitrogen bubbles.

[0035] See also Figure 5 The internal vortex flow pattern in the feed exhaust straight pipe and the shoulder height of the transition area between the feed exhaust straight pipe and the main glass flow in the channel And the liquid level height of the supply and exhaust straight pipe Related.

[0036] See also Figure 7 , the left side is a schematic diagram of the formation mechanism of the abnormal glass layer. The flow speed / temperature of the glass liquid at different positions of the internal vortex of the feeding and exhaust straight pipe and the mainstream area are obviously different. Due to the small diameter of the feeding and exhaust straight pipe, the shoulder is too tilted or the liquid level is relatively high, the free liquid surface is far away from the internal vortex and the main glass flow of the feeding bowl, the surface glass flows slowly (even stagnant), and undergoes surface volatilization (such as boron), slight changes in composition or slow crystallization for a long time. A layer of abnormal glass layer may be formed on the liquid surface at the top of the straight pipe. Any process fluctuation or other unstable action of the main glass flow, such as drastic fluctuations in furnace pressure, drastic fluctuations in liquid level, rod washing, sudden changes in viscosity and temperature, sudden changes in lead volume, sudden changes in ambient air flow or others, are necessary conditions for liquid level imbalance, but not sufficient conditions; only local physical damage to the liquid surface (bubbles or one of the inducements) is the necessary and sufficient condition for liquid level imbalance. The abnormal glass layer is introduced into the main glass flow from the imbalance due to pressure, and undesirable line defects, gloss loss defects or bright lines are generated in the fixed position range of the glass substrate. The composition of the bright line is generally the same as that of the basic glass, the regional thickness changes, and the waviness of the A / B surface of the glass substrate is convex. The position of the bright line is related to the physical damage position of the liquid surface, and may appear at the far end, near end or other positions.

[0037] See also Figure 7 , on the right is a schematic diagram of the formation mechanism of nitrogen bubbles. Since the liquid level of the feeding exhaust straight pipe (top of the feeding tank) is close to the main glass flow, and the glass flow in the feeding exhaust straight pipe is active. Any process fluctuations or other unstable actions, such as fluctuations in the furnace pressure of the pool furnace, fluctuations in the liquid level of the pool furnace, replacement of the cover brick + washing rod of the stirring tank, adjustment of the lead-out amount or viscosity and temperature, sudden changes in the ambient air flow, and others, will affect the fluctuation of the liquid level and cause local deformation or cutting (especially close to the wall). When the deformation recovers, a small amount of gas will be mixed to form small nitrogen bubbles (nitrogen bubbles may become one of the triggering factors of the bright line). It is also possible that individual nitrogen bubbles are involved in the vortex and inertially enter the main glass flow, resulting in the generation of nitrogen bubbles on the glass substrate, and in severe cases, bubble defects are formed. When the liquid level is too low, nitrogen bubbles may stay at the intersection of the vortex bottom and the main glass flow (the residence rate increases with the decrease of the liquid level). Therefore, the design of the structure of the feeding exhaust straight pipe and the liquid level height should consider both the generation of the abnormal glass layer and the generation of nitrogen bubbles.

[0038] See also Figure 8 , the free liquid surface layer (relatively static) on the upper part of the vortex zone is subjected to abnormal (or process operation) large impact (such as: furnace pressure fluctuation, pool furnace liquid level fluctuation, replacement of cover bricks + rod washing, surface nitrogen bubble sudden (burst) etc.), the relative balance (static) of the liquid surface is broken, causing the abnormal glass layer to tear (if nitrogen bubble impact, local small range tearing). The specific manifestations are: (1) The junction between the liquid surface and the wall is the most vulnerable area. At the imbalance point, the combined pressure first causes the upper and surrounding gases to be sucked back into the internal vortex flow, and then inertia enters the lower main glass flow, producing a bright line within the fixed position range of the glass substrate.

[0039] (2) After the back-sucked air enters, it creates an inward pressure on the surrounding abnormal glass, causing it to begin to enter the internal vortex flow, and then inertia enter the lower main glass flow, and after overflow, a bright line band is generated within the fixed position range of the glass substrate.

[0040] (3) When the bright line cycle ends, the last abnormal glass layer breaks and sucks in air, and then establishes a new local equilibrium with the surrounding glass liquid.

[0041] Embodiment 1 See also Figure 4 and Figure 6 The present invention provides a method for analyzing the formation of bright line defects on a glass substrate, comprising the following steps: obtaining parameters related to the feeding structure, including the shoulder height of the main glass flow transition zone and the diameter of the supply and exhaust straight pipe Liquid level ; According to the position relationship between the liquid level of the supply exhaust straight pipe and the main glass flow, set the liquid level height where nitrogen bubbles must be formed ; Based on diameter , Shoulder height , the internal vortex height related to the formation of the heterogeneous glass layer in the feed exhaust straight pipe is obtained through simulation ; Based on the positional relationship between the internal vortex and the main glass flow, calculate the liquid level height where nitrogen bubbles occasionally form ; Based on the principle of nitrogen bubbles and heterogeneous glass layer formation, according to the liquid level height of the supply and exhaust straight pipe The liquid level that must be formed with nitrogen bubbles , internal vortex height and the liquid level where nitrogen bubbles occasionally form The relationship between them is used to analyze the formation of bright line defects on glass substrates. Among them, nitrogen bubbles causing the liquid level to be unbalanced and leading to the tearing of the abnormal glass layer is a sufficient condition for the formation of bright line defects on glass substrates.

[0042] Specifically, set the liquid level at which nitrogen bubbles must form .

[0043] Specifically, when the diameter , Shoulder height When the following relations are satisfied:

[0044]

[0045] Obtaining Internal Vortex Height Using Flow Simulation , specifically: .

[0046] In this embodiment, Pro / Engineer software is used to perform modeling based on diameter and shoulder height, and Ansys Fluent software is used for fluid simulation. Of course, any other modeling software, simulation software or program algorithm can also be used. There is no specific limitation here, as long as the internal vortex height can be obtained through the simulation results.

[0047] Specifically, when When the liquid level of the supply exhaust pipe is too close to the main glass flow, any process fluctuation or other unstable action of the main glass flow will cause nitrogen bubbles to form near the wall of the liquid level of the supply exhaust pipe. The internal vortex coincides with the liquid level of the feed and exhaust straight pipe, making the liquid level of the feed and exhaust straight pipe completely active. The probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to cause the liquid level to be unbalanced and cause the abnormal glass layer to tear. Therefore, no bright line defects on the glass substrate will be formed.

[0048] Specifically, when Specifically include: Calculate the liquid level when nitrogen bubbles occasionally form , when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable actions in the main glass flow, which may cause occasional nitrogen bubbles to form near the wall of the feed exhaust straight pipe; When the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, the liquid surface of the feeding and exhaust straight pipe is fully active, the probability of forming an abnormal glass layer is 0, and there are no nitrogen bubbles to unbalance the liquid surface and cause the abnormal glass layer to tear. Therefore, no bright line defect of the glass substrate will be formed; however, when When the glass near the liquid surface of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. Therefore, there are nitrogen bubbles that cause the liquid surface to be unbalanced, resulting in the tearing of the abnormal glass layer and the formation of bright line defects on the glass substrate. when When, due to , the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, and after a long period of circulation, an abnormal glass layer will be formed; however, since the liquid level of the feeding and exhaust straight pipe exceeds the liquid level occasionally formed by nitrogen bubbles There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

[0049] Specifically, when Specifically include: Calculate the liquid level when nitrogen bubbles occasionally form , when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable movements in the main glass flow, which may cause occasional nitrogen bubbles to appear near the wall of the feed exhaust straight pipe. , the internal vortex coincides with the liquid level of the feeding and exhaust straight pipe, making the liquid level of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to unbalance the liquid level and cause the abnormal glass layer to tear, so no bright line defects will be formed on the glass substrate; when When the liquid level in the feed exhaust pipe exceeds the liquid level where nitrogen bubbles occasionally form , there is no nitrogen bubble causing the liquid level to be unbalanced, and, , the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, making the liquid surface of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0, so no bright line defect of the glass substrate will be formed; when When the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. However, the liquid level of the feeding and exhaust straight pipe exceeds the liquid level formed by nitrogen bubbles occasionally. There is no nitrogen bubble that causes the liquid level to be unbalanced, so there will be no bright line defects on the glass substrate Specifically, any process fluctuations or other unstable actions of the main glass flow include: fluctuations in the furnace pressure of the pool furnace, fluctuations in the liquid level of the pool furnace, replacement of the cover bricks + washing rods in the stirring tank, adjustment of the lead-out amount or viscosity temperature, and sudden changes in the ambient airflow.

[0050] Embodiment 2 See also Figure 5 , the diameter of the supply and exhaust straight pipe structure , Shoulder height of main glass flow transition zone Satisfies the following relationship:

[0051]

[0052] Obtaining Internal Vortex Height Using Flow Simulation , specifically , based on the positional relationship between the internal vortex and the main glass flow, the liquid level height of the occasional nitrogen bubble formation is calculated =50mm.

[0053] at this time, , the analysis is as follows: at this time, , specifically: .

[0054] when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable movements in the main glass flow, which may cause occasional nitrogen bubbles to appear near the wall of the feed exhaust straight pipe. , the internal vortex coincides with the liquid level of the feeding and exhaust straight pipe, making the liquid level of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to unbalance the liquid level and cause the abnormal glass layer to tear, so no bright line defects will be formed on the glass substrate; when When the liquid level in the feed exhaust pipe exceeds the liquid level where nitrogen bubbles occasionally form , there is no nitrogen bubble causing the liquid level to be unbalanced, and, , the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, making the liquid surface of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0, so no bright line defect of the glass substrate will be formed; when When the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. However, the liquid level of the feeding and exhaust straight pipe exceeds the liquid level formed by nitrogen bubbles occasionally. There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

[0055] Therefore, control the liquid level of the feed exhaust straight pipe for: .

[0056] Embodiment 3 See also Figure 5 , the diameter of the supply and exhaust straight pipe structure , Shoulder height of main glass flow transition zone Satisfies the following relationship:

[0057]

[0058] Obtaining Internal Vortex Height Using Flow Simulation , specifically , based on the positional relationship between the internal vortex and the main glass flow, the liquid level height of the occasional nitrogen bubble formation is calculated =75mm.

[0059] at this time, , the analysis is as follows: at this time, , specifically: .

[0060] when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable actions in the main glass flow, which may cause occasional nitrogen bubbles to form near the wall of the feed exhaust straight pipe; When the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, the liquid surface of the feeding and exhaust straight pipe is fully active, the probability of forming an abnormal glass layer is 0, and there are no nitrogen bubbles to unbalance the liquid surface and cause the abnormal glass layer to tear. Therefore, no bright line defect of the glass substrate will be formed; however, when When the glass near the liquid surface of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. Therefore, there are nitrogen bubbles that cause the liquid surface to be unbalanced, resulting in the tearing of the abnormal glass layer and the formation of bright line defects on the glass substrate. when When, due to , the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, and after a long period of circulation, an abnormal glass layer will be formed; however, since the liquid level of the feeding and exhaust straight pipe exceeds the liquid level occasionally formed by nitrogen bubbles There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

[0061] Therefore, control the liquid level of the feed exhaust straight pipe for: .

[0062] In summary, the physical mechanism of bright line generation: the formation of abnormal glass layer is related to the structure of the feeding and exhaust straight pipe (diameter, shoulder tilt height), liquid level, and internal independent vortex flow state. The system structure design (small straight pipe diameter, too large shoulder tilt, low liquid level) is the fundamental factor that increases the probability of bright line occurrence. (1) Surface bubbles suddenly appear (break) or crack; (2) The relative balance (stillness) of the liquid surface is broken, causing the surface abnormal glass layer to tear; (3) At the imbalance point, the combined pressure effect causes the surrounding gas to be sucked back into the internal vortex and inertially enter the main glass flow; (4) The surrounding abnormal glass is subjected to inward pressure and enters the internal vortex and inertially enters the main glass flow.

[0063] Therefore, among the conditions for the generation of bright lines, the generation of an abnormal glass layer on the liquid surface of the supply and exhaust straight pipe is a necessary condition for the generation of bright lines; if there is no abnormal glass layer, any triggering factor will never lead to the appearance of bright lines. Bright line triggering factors: Unstable operation leading to local physical damage to the liquid surface (nitrogen bubbles are one of the inducements) is a necessary and sufficient condition for liquid level imbalance, such as furnace pressure fluctuations, pool furnace liquid level fluctuations, replacement of cover bricks + rod washing, lead-out volume or viscosity temperature adjustment, sudden changes in ambient airflow, and other unstable factors. Among them, nitrogen bubbles causing the liquid surface to be unbalanced and leading to the tearing of the abnormal glass layer is a sufficient condition for the formation of bright line defects on glass substrates.

[0064] Based on the quality requirements of the production line for glass substrates, it is necessary not only to suppress the generation of bright lines, but also to avoid the formation of nitrogen bubble defects. for: When controlling the liquid level of the supply and exhaust straight pipe ,make .

[0065] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for analyzing the formation of bright line defects on a glass substrate, characterized in that: The following steps are involved: Obtain parameters related to the feeding structure, including the shoulder height of the main glass flow transition zone and the diameter of the supply and exhaust straight pipe Liquid level ; According to the position relationship between the liquid level of the supply exhaust straight pipe and the main glass flow, set the liquid level height where nitrogen bubbles must be formed ; Based on diameter , Shoulder height , the internal vortex height related to the formation of the heterogeneous glass layer in the supply and exhaust straight pipe is obtained through fluid simulation ; Calculate the liquid level where nitrogen bubbles occasionally form based on the positional relationship between the internal vortex and the main glass flow ; Based on the principle of nitrogen bubbles and heterogeneous glass layer formation, according to the liquid level height of the supply and exhaust straight pipe The liquid level that must be formed with nitrogen bubbles , internal vortex height and the liquid level where nitrogen bubbles occasionally form The relationship between them is used to analyze the formation of bright line defects on glass substrates. Among them, nitrogen bubbles causing the liquid level to be unbalanced and leading to the tearing of the abnormal glass layer is a sufficient condition for the formation of bright line defects on glass substrates.

2. The method for analyzing the formation of bright line defects on a glass substrate according to claim 1, characterized in that: Set the liquid level where nitrogen bubbles must form .

3. The method for analyzing the formation of bright line defects on a glass substrate according to claim 2, characterized in that: When diameter , Shoulder height When the following relations are satisfied: Obtaining Internal Vortex Height Using Flow Simulation , specifically: .

4. The method for analyzing the formation of bright line defects on a glass substrate according to claim 3, characterized in that: when When the liquid level of the supply exhaust pipe is too close to the main glass flow, any process fluctuation or other unstable action of the main glass flow will cause nitrogen bubbles to form near the wall of the liquid level of the supply exhaust pipe. The internal vortex coincides with the liquid level of the feed and exhaust straight pipe, making the liquid level of the feed and exhaust straight pipe completely active. The probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to cause the liquid level to be unbalanced and cause the abnormal glass layer to tear. Therefore, no bright line defects on the glass substrate will be formed.

5. The method for analyzing the formation of bright line defects on a glass substrate according to claim 3, characterized in that: when Specifically include: Calculate the liquid level when nitrogen bubbles occasionally form , when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable actions in the main glass flow, which may cause occasional nitrogen bubbles to form near the wall of the feed exhaust straight pipe; When the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, the liquid surface of the feeding and exhaust straight pipe is fully active, the probability of forming an abnormal glass layer is 0, and there are no nitrogen bubbles to unbalance the liquid surface and cause the abnormal glass layer to tear. Therefore, no bright line defect of the glass substrate will be formed; however, when When the glass near the liquid surface of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. Therefore, there are nitrogen bubbles that cause the liquid surface to be unbalanced, resulting in the tearing of the abnormal glass layer and the formation of bright line defects on the glass substrate. when When, due to , the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, and after a long period of circulation, an abnormal glass layer will be formed; however, since the liquid level of the feeding and exhaust straight pipe exceeds the liquid level occasionally formed by nitrogen bubbles There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

6. The method for analyzing the formation of bright line defects on a glass substrate according to claim 3, characterized in that: when Specifically include: Calculate the liquid level when nitrogen bubbles occasionally form , when When the liquid level of the feed exhaust straight pipe is close to the wall, the probability of nitrogen bubbles forming will gradually decrease as the liquid level of the feed exhaust straight pipe increases. However, since the liquid level of the feed exhaust straight pipe does not exceed the liquid level where nitrogen bubbles occasionally form, , there are still any process fluctuations or other unstable movements in the main glass flow, which may cause occasional nitrogen bubbles to appear near the wall of the feed exhaust straight pipe. , the internal vortex coincides with the liquid level of the feeding and exhaust straight pipe, making the liquid level of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0. There are no nitrogen bubbles to unbalance the liquid level and cause the abnormal glass layer to tear, so no bright line defects will be formed on the glass substrate; when When the liquid level in the feed exhaust pipe exceeds the liquid level where nitrogen bubbles occasionally form , there is no nitrogen bubble causing the liquid level to be unbalanced, and, , the internal vortex coincides with the liquid surface of the feeding and exhaust straight pipe, making the liquid surface of the feeding and exhaust straight pipe completely active, and the probability of forming an abnormal glass layer is 0, so no bright line defect of the glass substrate will be formed; when When the glass near the liquid level of the feeding and exhaust straight pipe tends to be like dead water, after a long period of circulation, an abnormal glass layer will be formed. However, the liquid level of the feeding and exhaust straight pipe exceeds the liquid level formed by nitrogen bubbles occasionally. There is no nitrogen bubble that causes the liquid level to be unbalanced, so no bright line defect of the glass substrate will be formed.

7. A method for analyzing the formation of bright line defects on a glass substrate according to any one of claims 1 to 6, characterized in that: Any process fluctuations or other unstable actions of the main glass flow specifically include: fluctuations in the furnace pressure of the pool furnace, fluctuations in the liquid level of the pool furnace, replacement of the cover bricks + washing rods in the stirring tank, adjustment of the lead-out amount or viscosity and temperature, and sudden changes in the ambient airflow.

8. A method for suppressing the formation of bright line defects on a glass substrate, characterized in that: Based on the analysis method for the formation of bright line defects on a glass substrate according to claim 5 or 6, when the internal vortex height for: When controlling the liquid level of the supply and exhaust straight pipe ,make , inhibiting the formation of bright line defects on the glass substrate.

9. The method for suppressing the formation of bright line defects on a glass substrate according to claim 8, characterized in that: When diameter =60 mm, shoulder height =47.55 mm, the internal vortex height is obtained through fluid simulation , specifically , control the liquid level of the supply and exhaust straight pipe for: .

10. The method for suppressing the formation of bright line defects in a glass substrate according to claim 8, characterized in that: When diameter =50 mm, shoulder height =76 mm, the internal vortex height is obtained through fluid simulation , specifically , control the liquid level of the supply and exhaust straight pipe for: .

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