Pull rate increasing method and device for designing forming and annealing transverse temperature distribution

Abstract

The present invention belongs to the technical field of glass substrate manufacturing. Disclosed are a pull rate increasing method and device for designing forming and annealing transverse temperature distribution. In the design method provided in the present invention, on the basis of six physical flow state characteristics of glass in an overflow, forming and annealing region, a forming and annealing process of a glass substrate is divided into an overflow area, a thickness formation area, a pre-annealing area, a soaking area, an annealing area and a subsequent annealing area. Moreover, in different annealing regions, differentiated transverse temperature distribution strategies are used, thereby realizing precise control of the design of glass forming and annealing transverse temperature distribution; and "temperature difference • structural difference • thermal stress" is used to deeply analyze a mechanism in a glass annealing process, thereby providing a more scientific and rational method for the warpage magnitude and curved-surface shape of the glass after the glass is annealed and cooled to room temperature. The method and the device are particularly suitable for the design of temperature distribution in forming and annealing regions of a glass substrate, which has a high pull rate and a large width and is thin.

Description

A method and device for designing a cross-sectional temperature distribution of a forming and annealing process for improving a draw rate TECHNICAL FIELD

[0001] The present application relates to the technical field of glass substrate manufacturing, and particularly relates to a method and device for designing a cross-sectional temperature distribution of a forming and annealing process for improving a draw rate. BACKGROUND

[0002] In the field of TFT-LCD (Thin Film Transistor-Liquid Crystal Display) flat panel display manufacturing, the production of glass substrates is of great importance, and the glass substrates manufactured by the overflow down-draw method have significant process and technical challenges. In particular, ensuring the thickness uniformity of the glass substrate, controlling the residual stress and warping are one of the key process technologies, which are closely related to the design and process control of the overflow forming and annealing device.

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

[0004] The forming and annealing area has the following characteristics: first, from top to bottom in the forming area, the glass is in the hardening process; second, when the glass is annealed, the edge of the glass substrate generally cools faster than the middle of the 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 and annealing area, and to keep the temperature difference between the edge and the middle of the forming and annealing area as consistent as possible from the forming area to the annealing area, so as to avoid the distortion of the edge caused by the unbalanced temperature difference (edge warping). Therefore, in the design of the glass substrate annealing process, special attention should be paid to the hardening process of the glass from the forming area to the annealing area, and the fine regulation of the temperature difference, so as to ensure the balance of the temperature difference between the far end and the middle, and thus avoid the distortion of the edge caused by the temperature difference.

[0005] In the design framework of the traditional glass substrate annealing process, designers have long relied on the classic relaxation theory, which relatively simply covers the three main physical states of melt, viscous plastic and elastic body, and accordingly roughly divides the annealing process into thickness forming stage, slow annealing stage and rapid annealing stage. However, with the continuous improvement of the research on glass material science and thermal history, a newer understanding of the relaxation theory has emerged.

[0006] This new theory deeply analyzes the complex and variable physical behavior of glass during the cooling process, and finely divides it into six distinct physical property stages: first, the free-flowing stage, the glass is in a highly liquid state with strong flowability; then the high-viscosity plastic stage, the viscosity increases significantly but still maintains a certain plastic deformation ability; followed by the elastic-plastic stage, the glass begins to exhibit both elastic and plastic properties; into the initial state of the elastomer, its elastic response is more significant, but has not yet reached a stable state; then the sub-rigid stage, the physical properties of the glass gradually approach rigidity, but still retain some internal relaxation activity; finally, the glass completely changes into a rigid body, and its physical properties tend to be stable and no longer change significantly with temperature.

[0007] This division not only deepens the understanding of the physical state transition during glass annealing, 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, resulting in glass products with better performance. Furthermore, considering the need to strictly distinguish between irreversible structural differences and reversible structural differences, as well as the narrow sense of stress relaxation and the broad sense of stress relaxation, viscosity (not just temperature) must be used as the dimension of physical properties when discussing the division of the glass annealing region.

[0008] Therefore, how to utilize viscosity and based on the six physical property stages during the cooling process of glass to solve the problem of simple temperature distribution design and inaccurate warpage control in the existing forming annealing region has become a technical problem that needs to be overcome by current technical personnel in the field. SUMMARY

[0009] The purpose of the present application is to provide a lead-out quantity improving forming annealing transverse temperature distribution design method and device to overcome the problem of simple temperature distribution design and inaccurate warpage control in the existing forming annealing region based on the traditional relaxation theory, which only considers three physical properties of melt, viscous plastic and elastomer.

[0010] The present application solves the above technical problems by the following technical solutions:

[0011] A lead-out quantity improving forming annealing transverse temperature distribution design method, comprising the following steps:

[0012] Step one, based on the physical flow state characteristics of the glass in the overflow forming annealing region in the updated relaxation theory, and combining the corresponding glass viscosity of the physical flow state characteristics, the overflow forming annealing region of the annealing furnace is divided into overflow zone, thickness forming zone, pre-annealing zone, soaking zone, annealing zone and subsequent annealing zone;

[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 one, the physical flow characteristics of the glass in the overflow zone are those of a free-flowing melt, corresponding to a glass viscosity range of [missing value]. The physical flow characteristics of the glass in the thickness formation region are that of a highly viscous plastic body, with a corresponding glass viscosity range of [missing value]. The physical flow properties of the glass in the pre-annealing zone are elasto-plastic, and the corresponding glass viscosity range is [missing value]. The physical flow characteristics of the glass in the soaking zone are those of an elastic body in its initial state, corresponding to a glass viscosity range of [missing value]. The physical flow properties of the glass in the annealing zone are subrigid, and the corresponding glass viscosity range is [missing value]. The physical flow properties of the glass in the subsequent annealing zone are rigid, and the corresponding glass viscosity is at least [value missing]. .

[0015] Furthermore, in step two, the design criteria for the lateral temperature distribution in the overflow zone are as follows:

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

[0017]

[0018] in, The temperature of the tip edge of the overflow brick in the overflow zone; The temperature at the center of the overflow brick tip in the overflow zone; Upper limit temperature for crystallization of glass Upper limit temperature for crystallization of glass The calculation method is as follows:

[0019]

[0020] in, Liquidus temperature The viscosity of glass is Temperature at time .

[0021] Furthermore, in step two, the design criteria for the lateral temperature distribution in the thickness formation zone are as follows:

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

[0023]

[0024] and setting the temperature difference in the transverse direction of the central part of the thickness forming zone to be 0 ℃~20 ℃, for controlling the temperature uniform distribution of the central part of the thickness forming zone;

[0025] wherein, is the temperature of the edge part of the thickness forming zone; is the temperature of the central part of the thickness forming zone.

[0026] Further, in step two, the design criteria of the transverse temperature distribution of 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 part temperature and the edge part temperature of the pre-annealing zone gradually decreases; and the transverse temperature distribution of the expansion softening point is designed as:

[0028]

[0029] wherein, the junction position of the thickness forming zone and the pre-annealing zone is the theoretical annealing starting point of the glass substrate, the junction position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, is the temperature of the edge part of the pre-annealing zone; is the temperature of the central part of the pre-annealing zone.

[0030] Further, in step two, the design criteria of the transverse temperature distribution of the soaking 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 part temperature and the edge part temperature of the soaking zone gradually decreases, and the transverse temperature distribution of the actual annealing starting point is designed as:

[0032]

[0033] wherein, the junction position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate, is the temperature of the edge part of the soaking zone; is the temperature of the central part of the soaking zone.

[0034] Further, in step two, the design criteria of the transverse temperature distribution of 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 part temperature and the edge part temperature of the annealing zone gradually decreases, and the transverse temperature distribution of the actual annealing lower limit point is designed as: ​​​

[0036]

[0037] wherein 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, is the edge temperature of the annealing zone; is the central temperature of the annealing zone.

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

[0039] From the actual annealing lower limit point of the glass substrate to the outlet position of the annealing furnace along the flow direction, the temperature difference between the central temperature and the edge temperature of the annealing zone gradually decreases, and the lateral temperature distribution of the outlet position of the annealing furnace is designed as:

[0040]

[0041] wherein the junction position of the annealing zone and the subsequent annealing zone is the actual annealing lower limit point of the glass substrate, is the edge temperature of the subsequent annealing zone; is the central temperature of the subsequent annealing zone.

[0042] A device for designing the lateral temperature distribution of the drawing amount improving forming annealing is used to realize the lateral temperature distribution design method of the drawing amount improving forming annealing.

[0043] Compared with the prior art, the positive progress effect of the present application is that:

[0044] The present application provides a lateral temperature distribution design method of the drawing amount improving forming annealing, which divides the forming annealing process of the glass substrate into an overflow zone, a thickness forming zone, a pre-annealing zone, a soaking zone, an annealing zone and a subsequent annealing zone based on six physical flow state characteristics of the overflow forming annealing zone glass: free flow, high viscous plasticity, elastic plasticity, elastic body initial state, sub-rigid body and rigid body. Meanwhile, in different annealing zones, differentiated lateral temperature distribution strategies are adopted, thereby realizing accurate control of the lateral temperature distribution design of the glass forming annealing; and the "temperature difference • structure difference • thermal stress" is used to deeply analyze the mechanism in the glass annealing process, thereby providing a more scientific and reasonable method for the warping size and curved shape of the glass after annealing and cooling to room temperature.

[0045] The device for designing the lateral temperature distribution of the drawing amount improving forming annealing provided by the present application not only makes the warping size and curved shape control of the annealed glass more accurate, but also improves the overall quality of the product, and is especially suitable for the forming annealing treatment of high-difficulty large-drawing amount, wide plate width and thin glass substrates.​ BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the present application and serve to explain the present application, and do not limit the present application in any manner.

[0047] Fig. 1 is a structural schematic diagram of an overflow system;

[0048] Fig. 2 is a structural schematic diagram of overflow down-draw glass;

[0049] Fig. 3 is a schematic diagram of temperature distribution design of a forming and annealing area in the present application.

[0050] Wherein, 1 is an overflow brick; 2 is an overflow channel; 3 is a glass liquid feeding device; 4 is a root of the overflow brick; 5 is a flow guide plate; 6 is a formed glass substrate; 7 is a down-draw direction of the glass substrate; W G is a width of the glass substrate specification; W Y is a width of the glass substrate flow guide plate. Embodiment of the present application

[0051] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative labor are within the scope of protection of the present application.

[0053] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0054] In the description of the embodiments of the present application, it should be noted that if the terms "upper", "lower", "horizontal", "inner" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" and the like 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 inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0056] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or can be detachably connected, or integrally connected; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0057] The present application will be further described in detail below in conjunction with the drawings, which is an explanation of the present application rather than a limitation.

[0058] Referring to FIG. 1, the overflow system is composed of an overflow brick 1 and a glass liquid supply device 3. An overflow groove 2 is formed in the overflow brick 1, and the bottom of the overflow brick 1 is an overflow brick root 4. When a glass substrate is manufactured in a molten overflow manner, the glass liquid melted by a glass melting furnace is supplied to the glass liquid supply device 3 in the molten overflow forming device in the forming process, and flows along the overflow groove 2 through the overflow brick 1 on both sides, and forms a glass substrate from the overflow brick root 4.

[0059] The glass melt is pushed from the proximal end to the distal end of the channel, driven by the mass force and pressure, and overcomes the laminar viscous resistance to advance and flow downward from the overflow weir. The fluid dynamics equation based on this principle integrates the effects of the above-mentioned forces, and is the basis for the design of the overflow channel. In the vertical plane of the overflow, the mass force and pressure are large enough, and the viscosity is relatively low, the effect of the transverse surface tension is small, and there is almost no transverse contraction; on the inclined plane, the component force of the mass force and pressure along the inclined plane decreases significantly, and the viscosity gradually increases, the effect of the transverse surface tension is highlighted, and there is obvious transverse contraction. Therefore, the inclined plane of the overflow brick is provided with a platinum material flow guide plate 5 at each of the proximal end and the distal end, for partially resisting the transverse contraction of the glass.

[0060] Referring to FIG. 2, the guide plate serves as the forming basis of the glass substrate, and in the process of down-draw forming of the glass substrate, the formed glass substrate 6 runs downward along the down-draw direction 7 of the glass substrate, the moving direction of the glass substrate running downward is the flow direction, the non-flow direction is perpendicular to the flow direction, i.e. from the proximal end to the distal end, the direction of the transverse temperature in the design method refers to the transverse direction along the width W of the glass substrate specification G , which has the same meaning as the commonly used term "non-flow direction" in the industry.

[0061] Referring to Fig. 3, the temperature gradient of the central part and the edge part of the substrate glass is controlled to reduce the residual stress, warpage and thickness difference of the substrate glass. The maximum stress birefringence is less than 0.6 nm, the warpage value is less than 0.15 mm, and the thickness difference is less than 10-15 μm. The temperature of the overflow brick tip is uniformly controlled at about 1150 DEG C (subject to actual process control specifications). The traditional three-stage division of the glass substrate annealing into the thickness forming zone, the slow annealing zone and the rapid annealing zone cannot accurately reveal the mechanism of the annealing stage. The present application divides the glass substrate annealing into the overflow zone, the thickness forming zone, the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone from the six physical state characteristics of free flow, high viscous plasticity, elastic plasticity, elastic body initial state, sub-rigid body and rigid body, and the two annealing stages of deformation annealing and non-deformation annealing, and the four annealing states of the best, the second best, the worst and the subsequent annealing. The technical route of the glass annealing furnace design is obtained, and the glass annealing mechanism is analyzed by using the temperature difference, the structure difference and the thermal stress. The pre-annealing zone is the deformation annealing, that is, the best annealing state; the soaking zone is the deformation annealing, that is, the second best annealing state; the annealing zone is the non-deformation annealing, that is, the worst annealing state; and the subsequent annealing zone is the subsequent annealing state. The glass annealing theory can be established according to the assumption of the six physical state characteristics, and the annealing furnace design and the annealing operation are guided. In combination with the use of the plane stress concept, the causes of the glass ribbon warpage, explosion and cutting obstacles can be analyzed. It is discussed that the viscosity (not only the temperature) must be used as the dimension of the physical characteristics for the glass annealing furnace, and the irreversible structure difference and the reversible structure difference, the narrow sense stress relaxation phenomenon and the broad sense stress relaxation phenomenon must be strictly distinguished. According to the updated research results of the glass thermal history, the glass experiences the viscosity (free flow, high viscous plasticity), the viscoelasticity (elastic plasticity, elastic body initial state, sub-rigid body) and the elasticity (rigid body) according to the cooling curve. Different transverse temperature distributions are applied to the glass state sections of the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone to ensure that the glass annealing cooled to room temperature has a stable curved shape.

[0062] The present application provides a kind of lead-out quantity promotion forming annealing transverse temperature distribution design method, including the following steps:

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

[0064] Specifically, the updated relaxation theory considers that in the forming and annealing process, the physical flow state characteristics of the glass include free flow, high viscous plasticity, elastoplasticity, elastomer initial state, sub-rigid body and rigid body, combined with the corresponding glass viscosity of the glass flow state characteristics, the overflow forming and annealing region is divided into overflow zone, thickness forming zone, pre-annealing zone, soaking zone, annealing zone and subsequent annealing zone. Among them, the physical flow state characteristic of the glass in the overflow zone is free-flowing melt, and the corresponding glass viscosity range is ; the physical flow state characteristic of the glass in the thickness forming zone is high viscous plasticity, and the corresponding glass viscosity range is ; the physical flow state characteristic of the glass in the pre-annealing zone is elastoplasticity, and the corresponding glass viscosity range is ; the physical flow state characteristic of the glass in the soaking zone is elastomer initial state, and the corresponding glass viscosity range is ; the physical flow state characteristic of the glass in the annealing zone is sub-rigid body, and the corresponding glass viscosity range is ; the physical flow state characteristic of the glass in the subsequent annealing zone is rigid body, and the corresponding glass viscosity is at least Since the subsequent annealing zone produces temporary stress, it is automatically eliminated with temperature equalization to room temperature, and has no substantial effect on annealing stress. In order to reduce the length of the entire device, the subsequent annealing zone can be appropriately shortened, and the outlet temperature can be relatively high. Therefore, the upper limit of the viscosity of the subsequent annealing zone is designed according to the outlet temperature of the annealing furnace.

[0065] Further, the glass viscosity is the viscosity of the overflow brick tip ; is the viscosity corresponding to the theoretical annealing starting point of the glass substrate ; is the viscosity corresponding to the dilatant softening point ; is the viscosity corresponding to the actual annealing starting point ; is the viscosity corresponding to the actual annealing lower limit The viscosity corresponding to the actual annealing lower limit is greater than the viscosity corresponding to the theoretical annealing lower limit (strain point) .

[0066] Step two, according to the above region division, combined with the principle of glass overflow forming: the molten glass flows downward along the two sides of the overflow face of the overflow brick overflow groove through the overflow brick overflow groove, and is formed by cooling and stretching with the help of traction. Different transverse temperature distribution design criteria are used for the overflow zone, the thickness forming zone, the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone, so as to control the thickness uniformity of the glass substrate after annealing and meet certain warping.

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

[0068] S1, the lateral temperature distribution of the overflow zone: the temperature range of the overflow zone is from the top of the overflow brick to the tip of the overflow brick . In this area, the physical flow state of the glass is a free-flowing melt, and the corresponding glass viscosity range is . Considering that the glass has a low viscosity in the overflow zone and is a flowing body, only the lateral temperature distribution of the tip of the overflow brick of the overflow zone is designed. Since the platinum material of the far and near end drainage plates cools down quickly, the actual edge is lower than the central part , the edge temperature is lower than the central part temperature is reduced , that is, based on the physical flow state of the glass in the overflow zone, which is a free-flowing melt, the lateral temperature distribution of the tip of the overflow brick of the overflow zone is designed as follows:

[0069]

[0070] wherein, is the edge temperature of the tip of the overflow brick of the overflow zone; is the central temperature of the tip of the overflow brick of the overflow zone;

[0071] At the same time, it is necessary to ensure that the edge temperature is not lower than the upper limit of crystallization temperature . The upper limit of crystallization temperature ; is the liquidus temperature, which is the highest temperature at which the crystal phase and the glass are in equilibrium. The liquidus temperature , a more viscous glass will grow unacceptable devitrification (crystal) defects, affecting the forming stability, and the overflow fusion needs high liquidus viscosity to minimize the crystallization devitrification of the finished glass.

[0072] S2, the lateral temperature distribution of the thickness forming zone: the physical flow state of the glass in the thickness forming zone is a highly viscous plastic body, and the corresponding glass viscosity range is ; due to the cooling of the edge roller, the non-flow direction temperature (lateral temperature) of the glass substrate decreases rapidly from the central part to the two edge parts , and the temperature of the edge part where the edge roller is located decreases the most compared with the central part , so it is necessary to suppress the non-flow direction shrinkage of the glass substrate to ensure sufficient drainage plate width and stability. However, the central part (except the edge plate part) basically maintains a uniform relative edge part Higher temperature, set the thickness of the central part of the transverse temperature difference The range is 0℃~20℃, control the thickness of the central part of the temperature distribution, to ensure the uniform distribution of glass substrate thickness, reduce the thickness of the difference. From the position of the edge of the glass to the theoretical annealing starting point The temperature difference between the central part of the temperature And the edge temperature Gradually reduced, the glass thickness is basically shaped as the target thickness. With the increase of the lead-out amount, the lead plate speed is accelerated, and more cooling is needed in this section to accelerate the glass thickness formation, and to expand more space for the subsequent glass transition zone ) To deal with the increase of flow rate and reduce the reheating shrinkage, so the transverse temperature Distribution of thickness forming area along the flow direction is designed as:

[0073]

[0074] Wherein, The edge temperature of the thickness forming area is T1; The central temperature of the thickness forming area is T2.

[0075] S3, the transverse temperature distribution of the pre-annealing zone is designed as: the physical flow state of the glass in the pre-annealing zone is elastoplastic body, and the corresponding glass viscosity range is From the theoretical annealing starting point of the glass substrate To the expansion softening point , see Figure 3, the non-flow direction temperature (transverse temperature) distribution in this interval gradually transitions from the uniform distribution in the central part of the thickness forming area to the nearly parabolic gradually decreasing distribution from the central part of the glass substrate To the edge The pre-annealing zone has a cooling unit (such as water cooling), and the thermodynamic and kinetic characteristics are structure group displacement and molecular displacement, and the revealed structure relaxation is 0. Although the annealing behavior has been theoretically achieved, it is still necessary to maintain a large temperature difference To provide a prerequisite for subsequent soaking and annealing. Therefore, the transverse temperature Distribution of the expansion softening point is designed as:

[0076]

[0077] Wherein, the intersection position of the thickness forming area and the pre-annealing zone is the theoretical annealing starting point of the glass substrate, the intersection position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, The edge temperature of the pre-annealing zone is T3; The central temperature of the pre-annealing zone is T4.

[0078] S4, the transverse temperature distribution of the soaking zone is designed as follows: the physical flow state of the glass in the soaking zone is elastomer initial state, and the corresponding glass viscosity range is ; from the expansion softening point of the glass substrate to the actual annealing starting point , the non-flow direction temperature gradient formed by the pre-annealing zone gradually decreases to the actual annealing starting point, and the overall vertical temperature drop speed from the expansion softening point to the actual annealing starting point is maintained to be very low. The soaking zone corresponds to the glass transition zone of the fusion overflow down-draw method , and the thermodynamic and kinetic characteristics are structural group displacement tending to molecular displacement. The viscosity sharply increases, so that the displacement activity and the differential deformation activity sharply decrease. Due to the slight decrease of the thermal conductivity coefficient with the temperature drop, even if the lower cooling speed is maintained, the thermal stress generated by the structural relaxation has been revealed to be measurable. The non-flow direction temperature of the flat glass is below the glass softening point to the annealing point temperature region. Along the flow direction, the absolute value of the temperature difference between the edge and the center tends to be small, and this region is the most effective region for controlling the thermal shrinkage and warping of the glass substrate. Therefore, the transverse temperature distribution of the actual annealing starting point is designed as follows:

[0079]

[0080] Wherein, the junction position of the pre-annealing zone and the soaking zone is the expansion softening point of the glass substrate, the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate, is the edge temperature of the soaking zone; is the center temperature of the soaking zone.

[0081] S5, the transverse temperature distribution of the annealing zone is designed as follows: the physical flow state of the glass in the annealing zone is sub-rigid body, and the corresponding glass viscosity range is ; from the actual annealing starting point of the glass substrate to the actual annealing lower limit , the non-flow direction temperature gradient formed by the pre-annealing zone further reduces the actual annealing lower limit, a lower vertical temperature drop speed is maintained from the actual annealing starting point to the actual annealing lower limit, the annealing stress, warpage and thermal shrinkage are further reduced. The annealing zone has transitioned to a completely elastic body (sub-rigid body) stage, although it appears to be non-deformation annealing, it is the last annealing state compared to the soaking zone and the pre-annealing zone, and corresponds to the stress control zone of the fusion down-draw method. The thermodynamic and kinetic characteristics are molecular displacement. Although it has not reached the degree that the stress is proportional to the strain and follows Hooke's law, it has shown the characteristics of a sub-rigid body. The temperature gradient of the flat glass in the non-flow direction tends to be minimized from the edge to the central region. The cooling speed of the central region of the flat glass is faster, forming a tensile stress in the flow direction and the non-flow direction central region 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 warpage of the glass substrate. Therefore, the lateral temperature distribution at the actual annealing lower limit point of the glass substrate is designed as:

[0082]

[0083] , the junction position of the soaking zone and the annealing zone is the actual annealing starting point of the glass substrate, the junction position of the annealing zone and the subsequent annealing zone is the actual annealing lower limit point of the glass substrate, is the edge temperature of the annealing zone; is the central temperature of the annealing zone.

[0084] S6, the lateral temperature distribution of the subsequent annealing zone is designed as: the physical flow state characteristic of the glass in the subsequent annealing zone is a rigid body, and the corresponding glass viscosity is at least from the actual annealing lower limit point of the glass substrate to the cutting position and naturally cooled to room temperature, the non-flow direction temperature gradient formed by the annealing zone further reduces to the forming annealing furnace outlet, and even forms a smaller reverse temperature gradient, and finally naturally cools to a uniform room temperature. This interval maintains a higher vertical temperature drop speed, and there is no actual annealing significance for the inherent annealing stress, warpage and thermal shrinkage. The subsequent annealing zone is a completely elastic body (rigid body) stage, 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 exposed, and there is no change until the uniform room temperature, which is a permanent stress. The temperature difference only produces a reversible structural difference, because there is no differential deformation, and the thermal stress caused by the complete exposure of the structural difference disappears with the temperature uniformity and is called a temporary stress. Before the temporary stress disappears, it is superimposed with the permanent stress at the vector coincidence position. When the single stress or superimposed stress exceeds the tensile strength of the glass, explosion will occur. Therefore, the lateral temperature distribution at the outlet position of the annealing furnace is designed as:

[0085]

[0086] wherein the junction position of the annealing zone and the subsequent annealing zone is the actual annealing lower limit point of the glass substrate, is the edge temperature of the subsequent annealing zone; is the central temperature of the subsequent annealing zone.

[0087] The present application provides a drawing amount improvement forming annealing transverse temperature distribution design method, which overcomes the limitation that the past simple division of the glass substrate annealing into a thickness forming zone, a slow annealing zone and a fast annealing zone using the "melt • viscous plastic body • elastic body" three stages cannot reveal the annealing stage mechanism. Based on the updated glass substrate relaxation theory, starting from the six physical flow state characteristics of free flow, high viscous plasticity, elastic plasticity, elastic body initial state, sub-rigid body and rigid body, the glass substrate forming annealing is divided into an overflow zone, a thickness forming zone, a pre-annealing zone, a soaking zone, an annealing zone, and a subsequent annealing zone. Different transverse temperature distributions are used for the overflow zone, the thickness forming zone, the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone to obtain the technical route of the glass forming annealing transverse temperature distribution design, and the "temperature difference • structure difference • thermal stress" deduction is used to analyze the glass annealing mechanism. The overflow forming transverse temperature distribution design idea, method and process established based on the developed glass substrate relaxation theory, relaxation mechanism and annealing program provides a more scientific design method and evaluation standard, which guarantees that the glass annealing cools to room temperature with reasonable warping size and curved surface shape, and is especially suitable for the fine design of the glass substrate forming annealing transverse temperature distribution of large drawing amount, wide plate width and thin type.

[0088] The above content only illustrates the technical idea of the present application and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical scheme falls within the protection scope of the claims of the present application.

Claims

1. A method for designing transverse temperature distribution in annealing for improved lead extraction, characterized in that, The method comprises the following steps: Step one: based on the physical flow state characteristics of overflow forming annealing area glass in the updating relaxation theory, and combining the corresponding glass viscosity of the physical flow state characteristics, the overflow forming annealing area of the annealing furnace is divided into overflow area, thickness forming area, pre-annealing area, soaking area, annealing area and subsequent annealing area; Step two: different transverse temperature distribution design criteria are respectively used for the overflow area, thickness forming area, pre-annealing area, soaking area, annealing area and subsequent annealing area.

2. The method of claim 1, wherein, In Step One, the physical flow regime of the glass in the overflow zone is a free flowing melt corresponding to a glass viscosity in the range of ; the physical flow regime of the glass in the thickness formation zone is a highly viscous plastic corresponding to a glass viscosity in the range of ; the physical flow regime of the glass in the pre-anneal zone is an elastic plastic corresponding to a glass viscosity in the range of ; the physical flow regime of the glass in the soak zone is an elastic body initial state corresponding to a glass viscosity in the range of ; the physical flow regime of the glass in the anneal zone is a sub-rigid body corresponding to a glass viscosity in the range of ; and the physical flow regime of the glass in the post-anneal zone is a rigid body corresponding to a glass viscosity of at least .

3. The method of claim 2, wherein, In step two, the transverse temperature distribution design criterion of the overflow area is specifically as follows: Based on the physical flow regime characteristics of the overflow zone glass as a free flowing melt, the lateral temperature The distribution design is: wherein, the temperature of the tip edge of the overflow brick of the overflow zone; temperature at the center of the spout brick tip of the spout area; Crystallization upper limit temperature of glass ; upper crystallization temperature of the glass The calculation mode is: wherein for the liquidus temperature, Glass viscosity is temperature of the time 。 4. The method of claim 1, wherein, In step two, the transverse temperature distribution design criterion of the thickness forming area is specifically as follows: transverse temperature of the thickness forming zone in the flow direction The distribution design is: And set the thickness of the central part of the transverse temperature difference The temperature of the central part of the thickness forming area is 0 ℃~20 ℃, which is used for controlling the temperature of the central part of the thickness forming area to be uniformly distributed; wherein temperature of the edge portion of the thickness formation region; The temperature of the central part of the thickness forming area.

5. The method of claim 1, wherein, In step two, the transverse temperature distribution design criterion of the pre-annealing area is specifically as follows: The temperature difference between the central portion temperature and the edge portion temperature of the pre-annealing zone gradually decreases from the theoretical annealing starting point of the glass substrate to the expansion softening point in the flow direction; and the lateral temperature of the expansion softening point is The distribution design is: The interface position of the thickness forming area and the pre-annealing area is the theoretical annealing starting point of the glass substrate, and the interface position of the pre-annealing area and the soaking area is the expansion softening point of the glass substrate, temperature of the edge portion of the pre-annealing zone; The temperature of the central part of the pre-annealing area.

6. The method of claim 1, wherein, In step two, the transverse temperature distribution design criterion of the soaking area is specifically as follows: The temperature difference between the central portion temperature and the edge portion temperature of the soaking zone gradually decreases from the expansion softening point of the glass substrate to the actual annealing starting point in the flow direction, and the lateral temperature difference at the actual annealing starting point is 10°C or less The distribution design is: 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, temperature of the edge portion of the soaking zone; The temperature of the central part of the soaking area.

7. The method of claim 1, wherein, In step two, the transverse temperature distribution design criterion of the annealing area is specifically as follows: The temperature difference between the central portion temperature and the edge portion temperature of the annealing zone gradually decreases from the actual annealing start point to the actual annealing lower limit point of the glass substrate in the flow direction, and the lateral temperature of the actual annealing lower limit point is The distribution design is: 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, temperature of the edge portion of the annealing zone; The temperature of the central part of the annealing area.

8. The method of claim 1, wherein, In step two, the transverse temperature distribution design criterion of the subsequent annealing area is specifically as follows: The temperature difference between the central portion temperature and the edge portion temperature of the annealing zone gradually decreases from the actual annealing lower limit point of the glass substrate to the exit position of the annealing furnace in the flow direction, and the lateral temperature of the exit position of the annealing furnace is made to be uniform The distribution design is: wherein the junction of the annealing zone and the subsequent annealing zone is the actual lower annealing limit point of the glass substrate, for the edge temperature of the subsequent annealing zone; The temperature of the central part of the subsequent annealing area.

9. A device for designing the transverse temperature distribution during annealing to improve lead extraction, characterized in that, A method for designing the transverse temperature distribution of the drawing and forming annealing is used to realize any one of claims 1~8.

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