Transverse temperature distribution design method and device for lead-out quantity lifting, forming and annealing

Abstract

The invention discloses a method and a device for designing transverse temperature distribution of lead-out quantity lifting, forming and annealing, and belongs to the technical field of glass substrate manufacturing. According to the design method provided by the invention, the forming annealing process of the glass substrate is divided into an overflow area, a thickness forming area, a pre-annealing area, a soaking area, an annealing area and a subsequent annealing area based on six physical flow state characteristics of glass in an overflow forming annealing area. Meanwhile, in different annealing areas, differential transverse temperature distribution strategies are adopted, so that accurate control over transverse temperature distribution design of glass forming annealing is achieved, and the mechanism in the glass annealing process is deeply analyzed by applying temperature difference, structural difference and thermal stress; a more scientific and reasonable method is provided for the warping size and the curved surface shape of the glass after the glass is annealed and cooled to the room temperature, and the method is particularly suitable for the design of the temperature distribution of a forming annealing area of a large-extraction-amount, wide-plate-width and thin glass substrate.

Description

Technical Field

[0001] The invention relates to the technical field of glass substrate manufacturing, and in particular to a method and a device for designing transverse temperature distribution of lead-out enhancement molding annealing. Background Art

[0002] In the field of TFT-LCD (thin-film transistor display) flat panel display manufacturing, the production of glass substrates is crucial, and the glass substrates manufactured by the overflow down-pull method have significant process and technical challenges. In particular, ensuring the uniformity of glass substrate thickness and controlling residual stress and warpage are key to process technology, and these factors are closely related to the design and process control of the overflow molding annealing device.

[0003] Warpage, as an important indicator of the quality of the final product, has various causes, including uneven heat distribution, improper viscosity control of the overflow brick tip, and interference from external forces. In order to effectively control warpage, the cooling curve from the root of the overflow brick to the strain point must be precisely controlled. Among them, the control of the forming annealing temperature is the key to determining the cooling curve.

[0004] The forming annealing area has the following characteristics: first, the glass is in the hardening process from top to bottom in the forming area; second, when the glass is annealed, the edge glass substrate generally dissipates heat faster than the middle glass substrate, that is, there is a temperature difference between the edge and the middle of the glass substrate; third, it is necessary to reasonably control the temperature difference between the edge and the middle of the forming annealing area, and try to keep the temperature difference from the edge to the annealing area as consistent as possible to avoid edge distortion (edge ​​warping) caused by unbalanced temperature difference. Therefore, in the design of the glass substrate annealing process, special attention needs to be paid to the hardening process of the glass from the forming area to the annealing area, as well as the fine control of the temperature difference, to ensure the balance of the temperature difference between the far end and the middle, thereby avoiding edge distortion caused by temperature difference.

[0005] In the design framework of traditional glass substrate annealing process, designers have long relied on the classical relaxation theory, which simplifies the three main physical states of melt, viscoplastic body and elastic body, and roughly divides the annealing process into thickness formation stage, slow annealing stage and fast annealing stage. However, with the continuous improvement of glass material science and thermal history research, a newer understanding of relaxation theory has emerged.

[0006] This new theory deeply analyzes the complex and changeable physical behavior of glass during the cooling process, and divides it into six distinct stages of physical properties: first is the free flow stage, when the glass is in a highly liquid state with strong fluidity; followed by a high viscosity-plastic stage, when the viscosity increases significantly, but still maintains a certain plastic deformation ability; followed by an elastic-plastic stage, when the glass begins to exhibit the dual characteristics of elasticity and plasticity; after entering the initial state of the elastic body, its elastic response is more significant, but it has not yet fully reached a stable state; followed by a sub-rigid stage, when the physical properties of the glass gradually approach rigidity, but still retains a certain internal relaxation activity; finally, the glass is completely transformed into a rigid body, and its physical properties tend to be stable and no longer change significantly with temperature changes.

[0007] This division not only deepens the understanding of the physical state transformation during the glass annealing process, but also provides a more scientific basis for optimizing the annealing process and improving the quality of glass substrates. By precisely controlling the cooling rate and temperature gradient at each stage, internal stress can be more effectively reduced and structural uniformity can be optimized, thereby producing glass products with better performance. In addition, considering the need to strictly distinguish between irreversible structural differences and reversible structural differences, and between stress relaxation in a narrow sense and stress relaxation in a broad sense, when discussing the division of glass annealing areas, viscosity (not just temperature) must be used as the dimension of physical properties.

[0008] Therefore, how to use viscosity and based on the six physical property stages of the glass cooling process to provide a method and device for designing the lateral temperature distribution of the forming annealing by increasing the lead-out amount has become a technical problem that needs to be overcome urgently by current technicians in this field. Summary of the invention

[0009] The purpose of the present invention is to provide a method and device for designing the lateral temperature distribution of the molding annealing with increased lead-out amount, so as to overcome the problems in the prior art that only three physical properties of the melt, viscous plastic body and elastomer are considered based on the traditional relaxation theory, resulting in simple temperature distribution design in the molding annealing area and inaccurate warpage control.

[0010] The present invention solves the above technical problems through the following technical solutions:

[0011] A method for designing transverse temperature distribution of lead-out enhancement forming annealing comprises the following steps:

[0012] Step 1: Based on the physical flow characteristics of the glass in the overflow forming annealing area in the updated relaxation theory and combined with the glass viscosity corresponding to the physical flow characteristics, the overflow forming annealing area of ​​the annealing furnace is divided into an overflow area, a thickness forming area, a pre-annealing area, a soaking area, an annealing area and a subsequent annealing area;

[0013] Step 2: different transverse temperature distribution design criteria are adopted for the overflow zone, thickness formation zone, pre-annealing zone, soaking zone, annealing zone and subsequent annealing zone.

[0014] Furthermore, in step 1, the physical flow characteristics of the glass in the overflow zone are free-flowing melt, and the corresponding glass viscosity range is 30K~(100K~160K) dPa·s; the physical flow characteristics of the glass in the thickness forming zone are high viscosity plastic, and the corresponding glass viscosity range is (100K~160K)~10 9 dPa·s; the physical flow characteristics of the glass in the pre-annealing zone are elastic-plastic, and the corresponding glass viscosity range is 10 9 ~10 12 dPa·s; the physical flow characteristics of the glass in the soaking zone are the initial state of elastic body, and the corresponding glass viscosity range is 10 12 ~10 13 dPa·s; the physical flow characteristics of the glass in the annealing zone are sub-rigid, and the corresponding glass viscosity range is 10 13 ~10 17.5 dPa·s; the physical flow characteristics of the glass in the subsequent annealing zone are rigid bodies, and the corresponding glass viscosity is at least 10 17.5 dPa·s.

[0015] Furthermore, in step 2, the design criteria for the lateral temperature distribution of the overflow area are as follows:

[0016] Based on the physical flow characteristics of the glass in the overflow area as a free-flowing melt, the lateral temperature ΔT1 distribution of the overflow brick tip in the overflow area is designed as follows:

[0017] 0℃≤ΔT1=T1 C -T1 E ≤20℃

[0018] Among them, T1 E T1 is the temperature of the tip edge of the overflow brick in the overflow area; C T1 is the temperature of the center of the overflow brick tip in the overflow area; E ≥ Glass crystallization upper limit temperature T XU ; The upper limit temperature of crystallization of glass is T XU The calculation method is:

[0019] T XU =T L -(12~22)℃

[0020] Among them, T L is the liquidus temperature, T L <Temperature T when glass viscosity is 160KdPa·s 160K .

[0021] Furthermore, in step 2, the design criteria for the transverse temperature distribution of the thickness forming zone are as follows:

[0022] The transverse temperature ΔT2 distribution of the thickness formation zone along the flow direction is designed as:

[0023] 120℃≤ΔT2=T2 C -T2 E ≤190℃

[0024] And set the lateral temperature difference ΔT2 in the center of the thickness forming area C The temperature range is 0℃~20℃, which is used to control the uniform distribution of the temperature in the center of the thickness forming area;

[0025] Among them, T2 E is the edge temperature of the thickness forming zone; T2 C It is the temperature in the center of the thickness forming zone.

[0026] Furthermore, in step 2, the design criteria for the transverse temperature distribution in the pre-annealing zone are as follows:

[0027] Along the flow direction, from the theoretical annealing starting point of the glass substrate to the expansion softening point, the temperature difference between the central temperature and the edge temperature of the pre-annealing zone gradually decreases; and the lateral temperature ΔT3 distribution of the expansion softening point is designed as:

[0028] 35℃≤ΔT3=T3 C -T3 E ≤50℃

[0029] The boundary between the thickness forming zone and the pre-annealing zone is the theoretical annealing starting point of the glass substrate, and the boundary between the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate. E is the edge temperature of the pre-annealing zone; T3 C is the central temperature of the pre-annealing zone.

[0030] Furthermore, in step 2, the design criteria for the transverse temperature distribution of the heat-saturating zone are as follows:

[0031] Along the flow direction, from the expansion softening point of the glass substrate to the actual annealing starting point, the temperature difference between the central temperature and the edge temperature of the soaking zone gradually decreases, and the lateral temperature ΔT4 distribution at the actual annealing starting point is designed as:

[0032] 17.5℃≤ΔT4=T4 C -T4 E ≤25℃

[0033] Among them, the junction position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, and the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate. Eis the edge temperature of the uniform heating zone; T4 C is the temperature in the center of the uniform heating zone.

[0034] Furthermore, in step 2, the design criteria for the transverse temperature distribution in the annealing zone are as follows:

[0035] Along the flow direction, from the actual annealing starting point of the glass substrate to the actual annealing lower limit point, the temperature difference between the central temperature and the edge temperature of the annealing zone gradually decreases, and the lateral temperature ΔT5 distribution of the actual annealing lower limit point is designed as:

[0036] 0℃≤ΔT5=T5 C -T5 E ≤15℃

[0037] Among them, the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate, and the junction position of the annealing zone and the subsequent annealing zone is the actual annealing lower limit point of the glass substrate. E is the edge temperature of the annealing zone; T5 C is the temperature in the center of the annealing zone.

[0038] Furthermore, in step 2, the design criteria for the lateral temperature distribution of the subsequent annealing zone are as follows:

[0039] Along the flow direction, from the actual annealing lower limit of the glass substrate to the exit position of the annealing furnace, the temperature difference between the central temperature and the edge temperature of the annealing zone gradually decreases, and the lateral temperature ΔT6 distribution at the exit position of the annealing furnace is designed as:

[0040] -35℃≤ΔT6=T6 C -T6 E ≤0℃

[0041] The boundary between the annealing zone and the subsequent annealing zone is the actual annealing lower limit of the glass substrate, T6 E is the edge temperature of the subsequent annealing zone; T6 C is the central temperature of the subsequent annealing zone.

[0042] A device for designing transverse temperature distribution of lead-out amount-enhancing forming annealing is manufactured by adopting any of the above-mentioned transverse temperature distribution design methods of lead-out amount-enhancing forming annealing.

[0043] Compared with the prior art, the positive and progressive effects of the present invention are:

[0044] The present invention provides a method for designing the transverse temperature distribution of the forming annealing with the lead-out amount increased. Based on the six physical flow characteristics of the glass in the overflow forming annealing area: free flow, high viscosity plasticity, elastic plasticity, initial state of elastic body, sub-rigid body and rigid body, the forming annealing process of the glass substrate is divided into an overflow area, a thickness forming area, a pre-annealing area, a soaking area, an annealing area and a subsequent annealing area. At the same time, in different annealing areas, a differentiated transverse temperature distribution strategy is adopted, thereby realizing the precise control of the transverse temperature distribution design of the glass forming annealing; and the "temperature difference, structural difference and thermal stress" are used to deeply analyze the mechanism in the glass annealing process, providing a more scientific and reasonable method for the warping size and curved surface shape of the glass after annealing and cooling to room temperature.

[0045] The present invention provides a device for designing the lateral temperature distribution of the lead-out amount during forming annealing, which not only makes the warping size and curved surface shape of the glass after annealing more accurately controlled, but also improves the overall quality of the product. The device is particularly suitable for forming annealing treatment of glass substrates with large lead-out amount, wide plate width and thin profile that require high difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] 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.

[0047] Figure 1 It is a structural schematic diagram of the overflow system;

[0048] Figure 2 It is a schematic diagram of the structure of overflow drop glass;

[0049] Figure 3 It is a schematic diagram of the temperature distribution design of the forming annealing area in the present invention.

[0050] Among them, 1 is the overflow brick; 2 is the overflow trough; 3 is the glass liquid feeding device; 4 is the root of the overflow brick; 5 is the guide plate; 6 is the formed glass substrate; 7 is the pull-down direction of the glass substrate; W G W is the width of the glass substrate; Y is the width of the glass substrate lead. DETAILED DESCRIPTION

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] See also Figure 1The overflow system is composed of an overflow brick 1 and a glass liquid feeding device 3. An overflow trough 2 is provided in the overflow brick 1, and the bottom of the overflow brick 1 is an overflow brick root 4. When the glass substrate is manufactured by a molten overflow method, the glass liquid melted by the glass melting furnace is supplied to the glass liquid feeding device 3 in the molten overflow molding device in the molding process, and overflows along the overflow trough 2 through both sides of the overflow brick 1, and forms a glass substrate from below the overflow brick root 4.

[0059] As the glass melt is pushed from the proximal end to the distal end of the overflow trough, it is pushed by the mass force and pressure in the running direction, overcomes the laminar viscous resistance and flows downward from the overflow weir. The fluid dynamics equation based on this principle integrates the effects of the above forces and is the basis for the design of the overflow trough. On the vertical surface of the overflow, the mass force and pressure are large enough, and the viscosity is relatively low, the effect of the lateral surface tension is very small, and there is almost no lateral contraction; on the inclined surface, the mass force and pressure components along the inclined surface become significantly smaller, and the viscosity gradually increases, the effect of the lateral surface tension becomes prominent, and a significant lateral contraction occurs. Therefore, a platinum material drainage plate 5 is provided at the proximal and distal ends of the inclined surface of the overflow brick to partially resist the lateral contraction of the glass.

[0060] See also Figure 2 The guide plate is used as the molding basis of the glass substrate. During the process of drawing down the glass substrate, the molded glass substrate 5 moves downward along the glass substrate drawing direction 6. The moving direction of the glass substrate moving downward is the flow direction, and the non-flow direction is perpendicular to the flow direction, that is, from the proximal end to the distal end. The direction of the lateral temperature in this design method refers to the direction along the specification width W of the glass substrate. G The horizontal direction has the same meaning as the commonly used term "non-directional" in the industry.

[0061] See also Figure 3The temperature gradient between the central and edge parts of the substrate glass is controlled to reduce the residual stress, warping and thickness range of the substrate glass. The maximum stress birefringence is less than 0.6nm, the warping value is less than 0.15mm, and the thickness range is less than 10μm to 15μm. The non-flow temperature of the overflow brick tip is uniformly controlled, about 1150℃ (subject to the actual process control specifications). Traditionally, the annealing of glass substrates is simply divided into thickness formation zone, slow annealing zone and fast annealing zone by using three stages of "melt·viscoplastic body·elastic body", which cannot accurately reveal the mechanism of the annealing stage. The present invention obtains the technical route of glass annealing furnace design from six physical property stages of free flow, high viscosity plasticity, elastic-plasticity, initial state of elastomer, sub-rigid body and rigid body, two annealing stages of deformation prevention annealing and non-deformation annealing, and four annealing states of optimal, suboptimal, worst annealing state and subsequent annealing, and uses "temperature difference·structural difference·thermal stress" deduction to analyze the glass annealing mechanism, wherein the pre-annealing zone is deformation prevention annealing 1, that is, the optimal annealing state; the soaking zone is deformation prevention annealing 2, that is, the suboptimal annealing state; the annealing zone is non-deformation annealing, that is, the worst annealing state; and the subsequent annealing zone is the subsequent annealing state. According to the assumption of six physical property stages, the glass annealing theory can be established to guide the design of annealing furnaces and annealing operations. Combined with the concept of plane stress, the causes of glass ribbon warping, cracking and cutting obstacles can be analyzed. It is discussed that the glass annealing furnace must use viscosity (not only temperature) as the dimension of physical properties, and strictly distinguish between irreversible structural differences and reversible structural differences, and between stress relaxation in a narrow sense and stress relaxation in a broad sense. According to the updated research results on the thermal history of glass, glass experiences glass states such as viscosity (free flow, high viscosity plasticity), viscoelasticity (elastic plasticity, initial state of elastic body, sub-rigid body) and elasticity (rigid body) according to its cooling curve. Different lateral temperature distributions are applied to each glass state section of the pre-annealing zone, soaking zone, annealing zone and subsequent annealing zone to ensure that the glass has a stable curved surface shape when annealed and cooled to room temperature.

[0062] The present invention provides a method for designing a transverse temperature distribution of a lead-out enhancement forming annealing, comprising the following steps:

[0063] Step 1. Based on the updated glass substrate relaxation theory, starting from the six physical flow characteristics of free flow, high viscosity plasticity, elastic plasticity, initial state of elastic body, sub-rigid body and rigid body, combined with glass viscosity, the glass substrate forming annealing is divided into overflow zone, thickness formation zone, pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone.

[0064] Specifically, the updated relaxation theory believes that during the forming annealing process, the physical flow characteristics of the glass include free flow, high viscosity plasticity, elastic plasticity, elastic initial state, sub-rigid body and rigid body. Combined with the glass viscosity corresponding to the flow characteristics of the glass, the overflow forming annealing area is divided into overflow area, thickness formation area, pre-annealing area, soaking area, annealing area and subsequent annealing area. Among them, the physical flow characteristics of the glass in the overflow area are free-flowing melts, and the corresponding glass viscosity range is 30K~(100K~160K)dPa·s; the physical flow characteristics of the glass in the thickness formation area are high viscosity plastic bodies, and the corresponding glass viscosity range is (100K~160K)~10 9 dPa·s; the physical flow characteristics of the glass in the pre-annealing zone are elastic-plastic, and the corresponding glass viscosity range is 10 9 ~10 12 dPa·s; the physical flow characteristics of the glass in the soaking zone are the initial state of elastic body, and the corresponding glass viscosity range is 10 12 ~10 13 dPa·s; the physical flow characteristics of the glass in the annealing zone are sub-rigid, and the corresponding glass viscosity range is 10 13 ~10 17.5 dPa·s; the physical flow characteristics of the glass in the subsequent annealing zone are rigid bodies, and the corresponding glass viscosity is at least 10 17.5 dPa·s, since the subsequent annealing zone generates temporary stress, it will automatically eliminate as the temperature is balanced when cooled to room temperature, and will not have a substantial effect on the annealing stress. In order to reduce the length of the entire device, the subsequent annealing zone can be shortened appropriately, and the outlet temperature can be relatively higher, so the upper limit of the viscosity of the subsequent annealing zone is determined according to the design of the outlet temperature of the annealing furnace.

[0065] Furthermore, the glass viscosity of 100K~160KdPa·s is the viscosity of the overflow brick tip η i ; 10 9 dPa·s is the viscosity η corresponding to the theoretical annealing starting point of the glass substrate T ; 10 12 dPa·s is the viscosity η corresponding to the expansion softening point d ; 10 13 dPa·s is the viscosity η corresponding to the actual annealing starting point a ; 10 17.5 dPa·s is the viscosity η corresponding to the actual annealing lower limit ae , the viscosity corresponding to the actual annealing lower limit is greater than the viscosity η corresponding to the theoretical annealing lower limit (strain point) st =10 14.5 dPa·s.

[0066] Step 2: Based on the above-mentioned area division and the principle of glass overflow forming, the molten glass flows downward along the overflow surfaces on both sides through the overflow trough of the overflow brick, bypasses the overflow weir, fuses at the tip of the overflow brick, and is formed by traction, stretching, cooling and forming. Different lateral temperature distribution design criteria are used for the overflow area, thickness formation area, pre-annealing area, soaking area, annealing area and subsequent annealing area, so as to control the thickness uniformity of the glass substrate obtained after annealing and meet a certain warpage.

[0067] The specific lateral temperature distribution design is as follows:

[0068] S1, lateral temperature distribution in the overflow area: The temperature ranges from the top of the overflow brick to the tip of the overflow brick is 1240~1155℃. In this area, the physical flow characteristics of the glass are free-flowing melts, and the corresponding glass viscosity range is 30K~(100K~160K)dPa·s. Considering that the glass has a low viscosity in the overflow area and is a fluid, only the lateral temperature distribution of the overflow brick tip in the overflow area is designed. Since the platinum material guide plates at the far and near ends dissipate heat faster, the actual edge (E) temperature is lower than that of the central part (C), and the edge (E) temperature is controlled to be T1 E The temperature of the center (C) is T1 C Reduce by ≤20℃, that is, based on the physical flow characteristics of the glass in the overflow area as a free-flowing melt, the lateral temperature ΔT1 distribution of the overflow brick tip in the overflow area is designed as:

[0069] 0℃≤ΔT1=T1 C -T1 E ≤20℃

[0070] Among them, T1 E T1 is the temperature of the tip edge of the overflow brick in the overflow area; C is the temperature of the center of the overflow brick tip in the overflow area;

[0071] At the same time, it is necessary to ensure the edge (E) temperature T1 E Not less than the upper limit of crystallization temperature (T XU ). Crystallization upper limit temperature T XU =T L -(12~22)℃;T L The liquidus temperature is the highest temperature at which the crystal phase and the glass can coexist in equilibrium. L <Temperature T when glass viscosity is 160KdPa·s 160K , more viscous glass will grow unacceptable devitrification (crystal) defects, affecting forming stability, and overflow fusion requires a high liquidus viscosity to minimize devitrification of the finished glass.

[0072] S2, transverse temperature distribution in thickness formation zone: The physical flow characteristics of glass in thickness formation zone are high viscosity plastic body, and the corresponding glass viscosity range is (100K~160K)~10 9 dPa·s; Due to the cooling of the edge pull wheel, the non-flow temperature (lateral temperature) of the glass substrate drops rapidly from the center (C) to the two sides (E). The edge (E) where the edge pull wheel is located has the largest temperature drop compared to the center (C). Therefore, it is necessary to suppress the non-flow shrinkage of the glass substrate to ensure sufficient guide plate width and guide plate stability. However, the center (C) (excluding the side plate part) basically maintains a uniform temperature that is higher than the side (E). The lateral temperature difference ΔT2 in the center of the thickness forming area is set C The range is 0℃~20℃, which controls the uniform temperature distribution in the center of the thickness forming area to ensure uniform thickness distribution of the glass substrate and reduce the thickness difference. From the edge pull wheel position to the theoretical annealing starting point η T =

[0073] 10 9 dPa·s, center temperature T2 C and edge temperature T2 E The temperature difference gradually decreases, and the glass thickness is basically set to the target thickness. As the lead-out volume increases and the lead-in speed increases, this section requires more cooling to accelerate the formation of glass thickness, while expanding more space for the subsequent glass transition zone (GTTR) to cope with the increase in flow rate and reduce reheating shrinkage. Therefore, the lateral temperature ΔT2 distribution of the thickness formation zone along the flow direction is designed as follows:

[0074] 120℃≤ΔT2=T2 C -T2 E ≤190℃

[0075] Among them, T2 E is the edge temperature of the thickness forming zone; T2 C It is the temperature in the center of the thickness forming zone.

[0076] S3, transverse temperature distribution in pre-annealing zone: The physical flow characteristics of glass in the pre-annealing zone are elastic-plastic, and the corresponding glass viscosity range is 10 9 ~10 12 dPa·s; from the theoretical annealing starting point of the glass substrate 10 9 dPa·s to expansion softening point 10 12 dPa·s, see Figure 3The non-flow temperature (lateral temperature) distribution in this interval gradually transitions from a uniform distribution in the center of the thickness formation zone to a nearly parabolic distribution that gradually decreases from the center (C) to the edge (E) of the glass substrate. There is a cooling unit (such as water cooling) in the pre-annealing zone. The thermodynamic and kinetic characteristics are structural group displacement and molecular displacement, and the revealed structural relaxation is 0. Although annealing behavior has been theoretically achieved, it is still necessary to maintain a large temperature difference to provide a prerequisite for subsequent equalization and annealing. Therefore, the lateral temperature ΔT3 distribution of the expansion softening point is designed as:

[0077] 35℃≤ΔT3=T3 C -T3 E ≤50℃

[0078] The boundary between the thickness forming zone and the pre-annealing zone is the theoretical annealing starting point of the glass substrate, and the boundary between the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate. E is the edge temperature of the pre-annealing zone; T3 C is the central temperature of the pre-annealing zone.

[0079] S4, lateral temperature distribution in the soaking zone: The physical flow characteristics of the glass in the soaking zone are the initial state of elastic body, and the corresponding glass viscosity range is 10 12 ~10 13 dPa·s; expansion softening point of glass substrate 10 12 dPa·s to the actual annealing starting point 10 13 dPa·s, the non-flow temperature gradient formed in the pre-annealing zone gradually decreases toward the actual annealing starting point, and an extremely low vertical cooling rate is maintained from the expansion softening point to the actual annealing starting point. The equalization zone corresponds to the glass transition zone (GTTR) of the melt overflow pull-down method, and the thermodynamic and kinetic characteristics are that the displacement of structural groups tends to molecular displacement. The sharp increase in viscosity causes a sharp decrease in displacement activity and differential deformation activity. Since the thermal conductivity decreases slightly with temperature drop, even if the lower cooling rate is maintained unchanged, the thermal stress generated by structural relaxation has been revealed and can be measured. The non-flow temperature of flat glass is the temperature region from below the glass softening point to the annealing point. Along the flow direction, the absolute value of the temperature difference between the edge (E) and the center (C) tends to be smaller, and this area is the most effective area for controlling thermal shrinkage and warping of the glass substrate. Therefore, the lateral temperature ΔT4 distribution at the actual annealing starting point is designed as:

[0080] 17.5℃≤ΔT4=T4 C -T4 E ≤25℃

[0081] Among them, the junction position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, and the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate. C is the edge temperature of the uniform heating zone; T4C is the temperature in the center of the uniform heating zone.

[0082] S5, lateral temperature distribution in annealing zone: The physical flow characteristics of glass in annealing zone are sub-rigid body, and the corresponding glass viscosity range is 10 13 ~10 17.5 dPa·s; from the actual annealing starting point of the glass substrate 10 13 dPa·s to the practical annealing lower limit of 10 17.5 dPa·s, the non-flow temperature (lateral temperature) gradient formed in the pre-annealing zone further decreases toward the actual annealing lower limit, and a low vertical cooling rate is maintained from the actual annealing starting point to the actual annealing lower limit, further reducing annealing stress, warping and thermal shrinkage. The annealing zone has transitioned to the stage of complete elastic body (sub-rigid body). Although it exhibits non-deformation annealing, it is already in the worst annealing state relative to the soaking zone and pre-annealing zone, corresponding to the stress control zone of the melt overflow pull-down method. The thermodynamic and kinetic characteristics are molecular displacement. Although it has not yet reached the level where stress is proportional to strain and follows Hooke's law, it has shown the characteristics of a sub-rigid body. The non-flow temperature of the flat glass tends to be minimized from the edge to the central area. The cooling rate in the central area of ​​the flat glass is faster, and tensile stress is formed in the flow and non-flow central parts of the glass substrate, and the tensile stress in the flow direction is much greater than that in the non-flow direction, thereby reducing the warping of the glass substrate. Therefore, the lateral temperature ΔT5 distribution of the actual annealing lower limit is designed as follows:

[0083] 0℃≤ΔT5=T5 C -T5 E ≤15℃

[0084] Among them, the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate, and the junction position of the annealing zone and the subsequent annealing zone is the actual annealing lower limit point of the glass substrate. E is the edge temperature of the annealing zone; T5 C is the temperature in the center of the annealing zone.

[0085] S6, lateral temperature distribution in the subsequent annealing zone: The physical flow characteristics of the glass in the subsequent annealing zone are rigid bodies, and the corresponding glass viscosity is at least 10 17.5 dPa·s from the actual annealing lower limit of glass substrate 10 17.5 dPa·s to the cutting position and naturally cooled to room temperature, the non-flow temperature gradient ΔT6 = T6 formed in the annealing zone C -T6 EIt further decreases toward the outlet of the forming annealing furnace, and even forms a smaller reverse temperature gradient, and finally cools naturally to a uniform room temperature. This interval maintains a high vertical cooling rate, and there is no practical annealing significance for inherent annealing stress, warping and thermal shrinkage. The subsequent annealing zone is already in the stage of complete elastic body (rigid body), and the thermodynamic and kinetic characteristics are particle vibration. The stress is proportional to the strain and follows Hooke's law. The structural difference is fully revealed until the uniform room temperature no longer changes, which is a permanent stress. The temperature difference only produces reversible structural differences. Because there is no differential deformation, the structural difference is fully revealed, and the resulting thermal stress that disappears with temperature uniformity is called temporary stress. Before the temporary stress disappears, it is superimposed with the permanent stress at the point where the vector coincides. When a single stress or superimposed stress exceeds the tensile strength of the glass, cracking will occur. Therefore, the lateral temperature ΔT6 distribution at the outlet of the annealing furnace is designed as:

[0086] -35℃≤ΔT6=T6 C -T6 E ≤0℃

[0087] The boundary between the annealing zone and the subsequent annealing zone is the actual annealing lower limit of the glass substrate, T6 E is the edge temperature of the subsequent annealing zone; T6 C is the central temperature of the subsequent annealing zone.

[0088] The present invention provides a method for designing the transverse temperature distribution of the lead-out-enhanced forming annealing, which overcomes the limitation that the past practice of simply dividing the annealing of the glass substrate into the thickness forming zone, the slow annealing zone and the fast annealing zone using the three stages of "melt·viscous plastic body·elastic body" cannot reveal the limitation of the annealing stage mechanism. Based on the updated glass substrate relaxation theory, starting from the six physical flow characteristics of free flow, high viscosity plasticity, elastic plasticity, initial state of elastic body, sub-rigid body and rigid body, the glass substrate forming annealing is divided into the overflow zone, the thickness forming zone, the pre-annealing zone, the soaking zone, the annealing zone, and the subsequent annealing zone. The technical route of designing the transverse temperature distribution of the glass forming annealing is obtained by using different transverse temperature distributions for the overflow zone, the thickness forming zone, the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone, and the "temperature difference·structural difference·thermal stress" deduction is used to analyze the glass annealing mechanism. The established design ideas, methods and processes for the lateral temperature distribution of overflow molding are based on the developed glass substrate relaxation theory, relaxation mechanism and annealing procedure, providing more scientific design methods and evaluation criteria to ensure that the glass has a reasonable warping size and curved surface shape when it is annealed and cooled to room temperature. It is particularly suitable for the refined design of the lateral temperature distribution of annealing for molding of glass substrates with large lead-out, wide plate width and thin profile.

[0089] 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 designing transverse temperature distribution of lead-out increasing forming annealing, characterized in that: The following steps are involved: Step 1: Based on the physical flow characteristics of the glass in the overflow forming annealing area in the updated relaxation theory and combined with the glass viscosity corresponding to the physical flow characteristics, the overflow forming annealing area of ​​the annealing furnace is divided into an overflow area, a thickness forming area, a pre-annealing area, a soaking area, an annealing area and a subsequent annealing area; Step 2: different transverse temperature distribution design criteria are adopted for the overflow zone, thickness formation zone, pre-annealing zone, soaking zone, annealing zone and subsequent annealing zone.

2. A method for designing transverse temperature distribution of lead-out enhancement forming annealing according to claim 1, characterized in that: In step 1, the physical flow characteristics of the glass in the overflow zone are free-flowing melt, and the corresponding glass viscosity range is 30K~(100K~160K)dPa·s; the physical flow characteristics of the glass in the thickness formation zone are high-viscosity plastic, and the corresponding glass viscosity range is (100K~160K)~10 9 dPa·s; the physical flow characteristics of the glass in the pre-annealing zone are elastic-plastic, and the corresponding glass viscosity range is 10 9 ~10 12 dPa·s; the physical flow characteristics of the glass in the soaking zone are the initial state of elastic body, and the corresponding glass viscosity range is 10 12 ~10 13 dPa·s; the physical flow characteristics of the glass in the annealing zone are sub-rigid, and the corresponding glass viscosity range is 10 13 ~10 17.5 dPa·s; the physical flow characteristics of the glass in the subsequent annealing zone are rigid bodies, and the corresponding glass viscosity is at least 10 17.5 dPa·s.

3. The method for designing the transverse temperature distribution of the lead-out amount-enhancing forming annealing according to claim 2, characterized in that: In step 2, the design criteria for the lateral temperature distribution in the overflow area are as follows: Based on the physical flow characteristics of the glass in the overflow area as a free-flowing melt, the lateral temperature ΔT1 distribution of the overflow brick tip in the overflow area is designed as follows: 0℃≤ΔT1=T1 C -T1 E ≤20℃ Among them, T1 E T1 is the temperature of the tip edge of the overflow brick in the overflow area; C T1 is the temperature of the center of the overflow brick tip in the overflow area; E ≥ Glass crystallization upper limit temperature T XU ; The upper limit temperature of crystallization of glass is T XU The calculation method is: T XU =T L -(12~22)℃ Among them, T L is the liquidus temperature, T L <Temperature T when glass viscosity is 160KdPa·s 160K .

4. The method for designing the transverse temperature distribution of the lead-out amount-enhancing forming annealing according to claim 1, characterized in that: In step 2, the design criteria for the transverse temperature distribution in the thickness formation zone are as follows: The transverse temperature ΔT2 distribution of the thickness formation zone along the flow direction is designed as: 120℃≤ΔT2=T2 C -T2 E ≤190℃ And set the lateral temperature difference ΔT2 in the center of the thickness forming area C The temperature range is 0℃~20℃, which is used to control the uniform distribution of the temperature in the center of the thickness forming area; Among them, T2 E is the edge temperature of the thickness forming zone; T2 C It is the temperature of the center of the thickness formation zone.

5. The method for designing the transverse temperature distribution of the lead-out amount-enhancing forming annealing according to claim 1, characterized in that: In step 2, the design criteria for the transverse temperature distribution in the pre-annealing zone are as follows: Along the flow direction, from the theoretical annealing starting point of the glass substrate to the expansion softening point, the temperature difference between the central temperature and the edge temperature of the pre-annealing zone gradually decreases; and the lateral temperature ΔT3 distribution of the expansion softening point is designed as: <h2 style=";text-align:left;direction:ltr">35℃≤ΔT3=T3<h2 style=";text-align:left;direction:ltr"> C <h2 style=";text-align:left;direction:ltr"> -T3<h2 style=";text-align:left;direction:ltr"> E <h2 style=";text-align:left;direction:ltr"> ≤50℃ The boundary between the thickness forming zone and the pre-annealing zone is the theoretical annealing starting point of the glass substrate, and the boundary between the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate. E is the edge temperature of the pre-annealing zone; T3 C is the central temperature of the pre-annealing zone.

6. The method for designing the transverse temperature distribution of the lead-out amount-enhancing forming annealing according to claim 1, characterized in that: In step 2, the design criteria for the transverse temperature distribution of the heat-saturating zone are as follows: Along the flow direction, from the expansion softening point of the glass substrate to the actual annealing starting point, the temperature difference between the central temperature and the edge temperature of the soaking zone gradually decreases, and the lateral temperature ΔT4 distribution at the actual annealing starting point is designed as: 17.5℃≤ΔT4=T4 C -T4 E ≤25℃ Among them, the junction position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, and the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate. E is the edge temperature of the uniform heating zone; T4 C is the temperature in the center of the uniform heating zone.

7. The method for designing transverse temperature distribution of lead-out enhancement forming annealing according to claim 1, characterized in that: In step 2, the design criteria for the transverse temperature distribution in the annealing zone are as follows: Along the flow direction, from the actual annealing starting point of the glass substrate to the actual annealing lower limit point, the temperature difference between the central temperature and the edge temperature of the annealing zone gradually decreases, and the lateral temperature ΔT5 distribution of the actual annealing lower limit point is designed as: 0℃≤ΔT5=T5 C -T5 E ≤15℃ Among them, the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate, and the junction position of the annealing zone and the subsequent annealing zone is the actual annealing lower limit point of the glass substrate. E is the edge temperature of the annealing zone; T5 C is the temperature in the center of the annealing zone.

8. The method for designing the transverse temperature distribution of lead-out increasing forming annealing according to claim 1, characterized in that: In step 2, the design criteria for the lateral temperature distribution in the subsequent annealing zone are as follows: Along the flow direction, from the actual annealing lower limit of the glass substrate to the exit position of the annealing furnace, the temperature difference between the central temperature and the edge temperature of the annealing zone gradually decreases, and the lateral temperature ΔT6 distribution at the exit position of the annealing furnace is designed as: <h2 style=";text-align:left;direction:ltr">-35℃≤ΔT6=T6<h2 style=";text-align:left;direction:ltr"> C <h2 style=";text-align:left;direction:ltr"> -T6<h2 style=";text-align:left;direction:ltr"> E <h2 style=";text-align:left;direction:ltr"> ≤0℃ The boundary between the annealing zone and the subsequent annealing zone is the actual annealing lower limit of the glass substrate, T6 E is the edge temperature of the subsequent annealing zone; T6 C is the central temperature of the subsequent annealing zone.

9. A device for designing the transverse temperature distribution of the lead-out amount for forming annealing, characterized in that: The invention is manufactured by adopting a design method for lateral temperature distribution of lead-out increasing forming annealing as described in any one of claims 1 to 8.

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