A drawing quantity improving overflow forming annealing device and a design method thereof

Abstract

The application discloses an overflow forming annealing device with improved drawing amount and a design method thereof, and belongs to the technical field of glass substrate manufacturing. A mature glass substrate overflow forming annealing device is selected as a design blueprint, geometric structure parameters, specific parameters and common parameters thereof are obtained as design references, a length similarity relationship of a thickness forming area is established, and a similarity relationship of lengths and heater powers of a pre-annealing area, a soaking area, an annealing area and a subsequent annealing area is established. According to the established similarity relationship, length parameters of the overflow forming annealing device with improved drawing amount are obtained, and the design of the glass substrate overflow forming annealing device is completed. By using the design method, the problem of a long cooling distance in traditional theory is overcome, more accurate, efficient and low-cost overflow forming annealing device design is realized, key forming quality indexes such as thickness, compression, stress and warping of the glass substrate are effectively guaranteed, and remarkable benefit improvement is brought to the glass substrate manufacturing industry.

Description

Technical Field

[0001] This invention relates to the field of glass substrate manufacturing technology, specifically to an overflow forming annealing apparatus for increasing lead yield and its design method. Background Technology

[0002] In the manufacturing of TFT-LCD (Thin Film Transistor Display) flat panel displays, the production of glass substrates plays a crucial role, and its production process mainly relies on the advanced overflow pull method. This method uses precise control to transport molten glass from a glass melting furnace to a specific molten overflow pull forming device, thereby forming a high-quality glass substrate.

[0003] To improve production efficiency and reduce overall manufacturing costs, the industry is constantly exploring innovative strategies. On the one hand, increasing lead-out volume has effectively expanded production capacity; on the other hand, through high-generation upgrades, higher-generation overflow forming annealing equipment has been designed, aiming to achieve wide-width, high-capacity production and compatibility with glass substrates of various thicknesses. Simultaneously, this innovation also focuses on shortening the overall length of the production line, significantly reducing the vertical distance from the base of the overflow brick to the separation point between the substrate and the glass ribbon.

[0004] In the design of overflow pull-down equipment, comprehensive considerations must be given to increasing production capacity, using high-strain point feedstocks, overall manufacturing, and reducing production line construction costs. Furthermore, ensuring the stability of FDM and BOD cross-cutting processes is also crucial. However, with the increase in lead-out rates and the implementation of higher-generation upgrades, controlling melt quality and forming quality has become a key technical challenge, especially in the manufacturing of LTPS / IGZO glass substrates, where thermal stability issues are particularly prominent.

[0005] The continuous and gradual change in the physical properties of glass as it cools from a molten state to room temperature is the core of annealing theory. The quality of forming annealing directly affects the performance of the glass substrate. Traditional theory simplifies this process as a continuous change from "melt (viscous) → viscous plastic (viscoelastic) → elastomer". However, forming annealing apparatus designed based on this theory often requires a longer cooling distance when using a uniform scaling-up method, thus increasing capital investment.

[0006] To achieve breakthroughs in high lead-out / thinning and LTPS / IGZO technologies, more precise cooling control of the forming section is essential. Product quality can be improved by reducing the length of the target thickness region during forming, widening the glass transition zone (GTTR), and reducing compression. In terms of annealing design and process control, cutting-edge theories, concepts, and guidelines need to be introduced, combined with updated annealing thermodynamic mechanisms, comprehensively considering key factors such as glass substrate annealing design, forming annealing device length design, annealing cooling curve design, design of the correlation between stress and warpage of multiple (short) rollers, and control of the chimney effect and ambient pressure difference.

[0007] Recent research on the thermal history of glass indicates that glass undergoes multiple glassy states during cooling, including viscous (free flow, high viscous plasticity), viscoelastic (elastoplastic, initial elastomer state, subrigid body), and elastic (rigid body). To optimize the annealing process, different proportional rules need to be applied based on the characteristics of each glassy state. By rapidly cooling to reduce the distance in the viscous region, extending the vitrification and annealing time, and appropriately reducing the elastic region interval, quality indicators such as stress and compression can be improved while maintaining the physical shell of the forming device unchanged. In the viscous region, radiation dominates the cooling curve, and changes in cooling method or time have almost no effect on compression; therefore, a fixed length can be maintained, and the thickness formation zone can be shortened by rapid cooling. In the viscoelastic region, compression, residual stress, and shape are basically determined; the length of this region is closely related to factors such as flow rate, viscosity, and strain point. In the elastic region, as a non-value-adding region, the temporary stress caused by uneven cooling should be minimized. It is evident that the quality of forming annealing encompasses multiple aspects such as annealing stress, thermal shrinkage, BOW shape and warpage, and thermal stability of the glass substrate. Only by introducing a comprehensive perspective of "temperature difference, structural difference, and thermal stress" to analyze the annealing mechanism of glass can we provide a more comprehensive and in-depth theoretical basis for annealing theory.

[0008] Therefore, how to provide an overflow forming annealing device and its design method to improve the yield and overcome the misconceptions in traditional theory has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to provide an overflow forming annealing device with improved lead-out volume and its design method, so as to overcome the problem of excessively long cooling distance in the forming annealing device designed based on traditional theory in the prior art.

[0010] The present invention solves the above-mentioned technical problems through the following technical solution:

[0011] A design method for an overflow forming annealing device with improved yield includes the following steps:

[0012] Step 1: Select a mature glass substrate overflow forming annealing apparatus as the reference forming annealing apparatus, and obtain the geometric structure parameters, specific parameters, and common parameters of the reference forming annealing apparatus. The geometric structure parameters include the length of the thickness forming zone of the reference apparatus. Length of pre-annealing zone Length of the heat spreader Annealing zone length and the length of the subsequent annealing zone Specific parameters include the heating power of the pre-annealing zone heater. Heating power of the heat spreader heater Heating power of the annealing zone heater and the heating power of the heater in the subsequent annealing zone Extraction volume Overflow brick overflow surface width Glass substrate specifications and width Average edge width of glass substrate and the height of the overflow brick slope Common parameters include the half-angle of the overflow brick slope. Density of glass substrate and viscosity at the base of the overflow brick ;

[0013] Step 2: Based on the parameters obtained in Step 1, calculate the unit length lead-out amount of the reference forming annealing device. Critical contraction width of the drainage plate and the width of the guide plate ;

[0014] Step 3: Based on the parameters obtained in Step 1 and the parameters calculated in Step 2, calculate the thickness of the glass ribbon leaving the base of the overflow brick in the reference forming annealing device. and the speed of the pilot plate ;

[0015] Step 4: Draw out the required amount per unit length The thickness of the glass strip away from the base of the overflow brick Establish length similarity relationships for the thickness formation zone; based on the obtained pre-annealing zone length... Length of the heat spreader Annealing zone length Length of subsequent annealing zone and the speed of the guide plate The length similarity relationships of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone are established respectively; based on the obtained heating power of the pre-annealing zone heater... Heating power of the heat spreader heater Heating power of the annealing zone heater and the heating power of the heater in the subsequent annealing zone Establish similarity relationships in heating power between heaters in the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone;

[0016] Step 5: Based on the length similarity of the thickness forming zone, the length similarity of the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone, and the heating power similarity of the heaters in the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone, complete the design of the overflow forming annealing device for increasing the lead-out amount.

[0017] Furthermore, the unit length lead-out amount of the reference molding annealing device Based on the obtained extraction volume and overflow brick overflow surface width The calculation is as follows:

[0018]

[0019] Furthermore, the critical shrinkage width of the guide plate of the reference molding annealing device... To determine the overflow surface width of the overflow brick and the height of the overflow brick slope The calculation is as follows:

[0020]

[0021] Furthermore, the width of the guide plate of the reference molding annealing device To determine the width based on the obtained glass substrate specifications and the average edge width of the glass substrate The calculation is as follows:

[0022]

[0023] in, The edge panel cutting factor. Average edge width of glass substrate It is 150~175 mm.

[0024] Furthermore, the thickness of the glass strip from the base of the overflow brick in the reference molding annealing apparatus... Based on the obtained half angle of the overflow brick slope Density of glass substrate Viscosity at the base of the overflow brick and the amount of lead-out per unit length The calculation is as follows:

[0025]

[0026] Where g is the acceleration due to gravity.

[0027] Furthermore, the speed of the guide plate in the reference molding annealing device... To determine the density of the obtained glass substrate Overflow brick overflow surface width Glass substrate specifications and width , width of the guide plate and the critical shrinkage width of the drainage plate The calculation is as follows:

[0028]

[0029] in, The thickness of the glass substrate is the target molding thickness.

[0030] Furthermore, the length similarity relationship of the thickness formation region is specifically as follows:

[0031]

[0032] in, The unit length lead-out amount for the design forming annealing device is specifically as follows:

[0033]

[0034] The thickness of the glass ribbon separating the annealing device from the base of the overflow brick is specifically designed as follows:

[0035]

[0036] To design the thickness forming zone length of the forming annealing apparatus, To design the lead-out amount of the forming annealing device, The overflow surface width of the overflow brick in the design of the molding annealing device.

[0037] Furthermore, the length similarity relationship of the pre-annealing zone is specifically as follows:

[0038]

[0039] The specific similarity relationship of the lengths of the homogeneous heating zone is as follows:

[0040]

[0041] The specific similarity relationship of the annealing zone lengths is as follows:

[0042]

[0043] The specific similarity relationship of the lengths of the subsequent annealing regions is as follows:

[0044]

[0045] in, The specific speed of the guide plate for the forming annealing device is as follows:

[0046]

[0047] The design guide plate width for the forming annealing device is as follows:

[0048]

[0049] To design the glass substrate width specifications for the molding annealing apparatus, The average edge width of the glass substrate in the design forming annealing apparatus is 150~175 mm.

[0050] The critical shrinkage width of the guide plate for designing the forming annealing apparatus is specifically as follows:

[0051]

[0052] To design the overflow slope height of the overflow brick; , , , These refer to the lengths of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone in the design forming annealing apparatus. , , , These are the guide plate speed adjustment coefficients for the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the design forming annealing apparatus, respectively. , , , , The width of the design guide plate for designing the forming annealing device.

[0053] Furthermore, the specific heating power similarity relationship of the pre-annealing zone heaters is as follows:

[0054]

[0055] The specific heating power similarity relationship of the heaters in the heat spreader zone is as follows:

[0056]

[0057] The specific heating power similarity relationship of the annealing zone heaters is as follows:

[0058]

[0059] The specific heating power similarity relationship of the heaters in the subsequent annealing zone is as follows:

[0060]

[0061] in, , , , These refer to the heating power of the heaters in the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the design forming annealing apparatus.

[0062] An overflow forming annealing apparatus for increasing lead yield is designed and manufactured based on the above-mentioned design method for overflow forming annealing apparatus for increasing lead yield.

[0063] Compared with the prior art, the positive and progressive effects of the present invention are as follows:

[0064] This invention provides a design method for an overflow forming annealing device with enhanced yield. It not only considers the changes in physical properties of glass during cooling, from free flow, high viscosity plasticity, elastoplasticity, the initial state of an elastomer, to a subrigid body, and finally to a rigid body, but also strictly distinguishes between irreversible and reversible structural differences, and narrow and broad stress relaxation phenomena. Furthermore, it fully considers the two key annealing stages of preventing deformation and non-deformation annealing, as well as the influence of four annealing states: optimal, second-best, worst, and subsequent annealing. A comprehensive analysis method of "temperature difference, structural difference, and thermal stress" is employed to deeply analyze the annealing mechanism of glass, thereby ensuring precise control of forming quality aspects such as thickness, compression, stress, and warpage during the annealing process. By rapidly cooling to reduce the viscous zone distance, extending the vitrification and annealing zone time, and appropriately reducing the elastic zone interval, the physical shell of the forming device remains unchanged while improving quality indicators such as stress and compression.

[0065] Furthermore, the overflow forming annealing apparatus provided by this invention fully considers eight key aspects, including overflow forming material supply, overflow, forming, warpage, annealing, BOW forming, BOD, and environmental airflow control. Based on advanced glass substrate relaxation theory, relaxation mechanism, and annealing procedures, compared to traditional annealing apparatuses designed using a uniform scaling method, the overflow forming annealing apparatus provided by this invention can achieve a more precise, efficient, and cost-effective annealing process using the overflow method. It is particularly suitable for the refined design of annealing apparatuses for forming and annealing large-volume, wide-format, and thin glass substrates, while also meeting the refined performance design requirements of LTPS / IGZO glass substrate forming and annealing apparatuses. Attached Figure Description

[0066] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0067] Figure 1 This is a schematic diagram of the overflow forming system of the present invention;

[0068] Figure 2 This is a schematic diagram of the overflow forming pull-down glass structure of the present invention;

[0069] Figure 3 This is a partial structural schematic diagram of the overflow forming pull-down glass of the present invention;

[0070] Figure 4 This is a schematic diagram of the overflow forming annealing device of the present invention.

[0071] Among them, 1 is the overflow brick, 2 is the overflow trough, 3 is the glass melt supply device, 4 is the root of the overflow brick, 5 is the guide plate, 6 is the forming glass substrate, and 7 is the downward pull direction of the glass substrate. For glass substrate specifications, width, For the width of the glass substrate lead plate, For the overflow brick overflow surface width, For the critical contraction width of the drainage plate, The height of the overflow slope. Detailed Implementation

[0072] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0073] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0074] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0075] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0076] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0077] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0078] The present invention will be further described in detail below with reference to the accompanying drawings. These descriptions are for explanation purposes only and not for limitation.

[0079] See Figure 1 The overflow forming system consists of an overflow brick 1 and a glass melt supply device 3 connected together. An overflow groove 2 is provided inside the overflow brick 1, and the bottom of the overflow brick 1 is the overflow brick root 4. When the glass substrate is manufactured by molten overflow, the glass melt melted by the glass melting furnace is supplied to the glass melt supply device 3 in the molten overflow forming device during the forming process, and overflows along the overflow groove 2 through both sides of the overflow brick 1, forming the glass substrate from below the overflow brick root 4.

[0080] As the molten glass propels from the near end to the far end of the overflow channel 2, it is propelled by mass force and pressure in the direction of travel, overcoming laminar viscous resistance, and flows downwards from the overflow weir. The fluid dynamics equations based on this principle integrate the effects of these forces and form the foundation of the overflow channel design. On the vertical overflow plane, the mass force and pressure are sufficiently large, and the viscosity is relatively low, resulting in minimal influence from lateral surface tension and almost no lateral contraction. On the inclined plane, the components of the mass force and pressure along the inclined plane decrease significantly, and the viscosity gradually increases, highlighting the effect of lateral surface tension and causing noticeable lateral contraction. Therefore, a platinum guide plate 5 is installed at both the near and far ends of the inclined surface of the overflow brick to partially resist the lateral contraction of the glass.

[0081] See Figure 2 During the glass substrate pulling process, the platinum guide plate 5 serves as the forming base for the glass substrate, and the formed glass substrate 6 moves downward along the glass substrate pulling direction 7.

[0082] See Figure 3 In the picture The width of the glass substrate is specified. The width of the glass substrate lead plate. The overflow surface width of the overflow brick. This is the critical contraction width of the drainage plate. This refers to the height of the overflow slope. During the downward forming process, the molten glass gradually forms the glass substrate along the glass guide plate. In the width direction, from the center to both ends of the glass substrate, the thickness of the glass substrate in the middle is thin and uniform, and the thickness of the glass substrate gradually increases from the center to the two sides. To determine the width of the target glass substrate, the middle section with uniform thickness is typically selected; the width of the lead plate is then determined. Remove glass substrate width specifications This is the thickness of the edge plate that needs to be removed.

[0083] See Figure 4 The temperature range of the thickness forming zone in different functional sections of the forming annealing furnace device is as follows: The temperature range of the pre-annealing zone is: The temperature range of the homogenization zone is: The temperature range of the annealing zone is: The temperature range of the subsequent annealing zone is The viscosity corresponding to different temperature ranges is: overflow brick tip temperature. Set the corresponding viscosity. The theoretical annealing initiation temperature of the glass substrate Set the corresponding viscosity. Expansion and softening point temperature Set the corresponding viscosity. Actual annealing start temperature Set the corresponding viscosity. The temperature at which the strain point is the lower limit of annealing. Set the corresponding viscosity. Annealing furnace outlet temperature Corresponding viscosity Among them, the overflow brick tip temperature Corresponding viscosity , Annealing furnace outlet temperature Preferably, .

[0084] A design method for an overflow forming annealing apparatus for glass substrates with improved lead extraction includes the following steps:

[0085] Step 1: Select a mature glass substrate overflow forming annealing apparatus as a design reference, and obtain the geometric structural parameters, specific parameters, and common parameters of the design reference forming annealing apparatus. The geometric structural parameters include the thickness forming zone length of the reference apparatus. Length of pre-annealing zone Length of the heat spreader Annealing zone length and the length of the subsequent annealing zone The specific parameters include the heating power of the pre-annealing zone heater. Heating power of the heat spreader heater Heating power of the annealing zone heater and the heating power of the heater in the subsequent annealing zone Extraction volume Overflow brick overflow surface width Glass substrate specifications and width Average edge width of glass substrate and the height of the overflow brick slope The common parameters include the half-angle of the overflow brick slope. Density of glass substrate and viscosity at the base of the overflow brick ;

[0086] Step 2: Based on the parameters obtained in Step 1, calculate the unit length lead-out amount of the reference forming annealing device. Critical contraction width of the drainage plate and the width of the guide plate ;

[0087] Step 3: Based on the parameters obtained in Step 1 and the parameters calculated in Step 2, calculate the thickness of the glass ribbon leaving the base of the overflow brick in the reference forming annealing device. and the speed of the pilot plate ;

[0088] Step 4: Based on the unit length lead-out amount, the thickness of the glass strip leaving the root of the overflow brick, and the target forming thickness, establish a similarity relationship for the length of the thickness forming zone; based on the lead-out plate speed, establish a similarity relationship for the length of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone; based on the heating power of the heaters in the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone, establish a similarity relationship for the heating power of the heaters in the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone.

[0089] Based on the above similarity relationship, the design of the overflow forming annealing device for glass substrates was completed.

[0090] Furthermore, the formula for the unit length lead-out amount of the forming annealing device is:

[0091]

[0092]

[0093] in, The lead-out amount is for designing the molding annealing device; For reference to the lead-out amount of the forming annealing device; To design the overflow surface width of the overflow brick in the molding annealing device; For reference, the overflow surface width of the overflow brick in the molding annealing device; The unit length lead-out amount for designing the forming annealing device; For reference, the amount of material drawn out per unit length in the forming annealing device.

[0094] Furthermore, the formula for the thickness of the glass ribbon leaving the base of the overflow brick in the forming annealing device is:

[0095]

[0096]

[0097] in, The thickness of the glass strip leaving the base of the overflow brick in the design of the molding annealing device; For reference, the thickness of the glass strip leaving the base of the overflow brick in the forming annealing device; It is half the angle of the overflow slope of the overflow brick; The density of the glass substrate; It is the acceleration due to gravity; The viscosity at the base of the overflow brick.

[0098] Furthermore, the formula for designing the width of the lead plate is:

[0099]

[0100]

[0101] in, , The width of the lead plate for the design and reference molding annealing apparatus are respectively; , The average edge width of the glass substrate for the design and reference molding annealing apparatus, respectively. , ; The edge panel cutting factor. ; , The width of the glass substrate is specified for the design and reference molding annealing apparatus.

[0102] Furthermore, the formula for the critical contraction width of the drainage plate is:

[0103]

[0104]

[0105] in, , The critical shrinkage width of the guide plate for the design and reference molding annealing apparatus; , These refer to the overflow ramp height for designing and referencing overflow bricks; , The overflow surface width of the overflow brick is respectively designed for the reference molding annealing device.

[0106] Furthermore, the formula for the speed of the guide plate in the forming annealing device is:

[0107]

[0108]

[0109] in, To design the sprue speed of the forming annealing device; For reference, the speed of the guide plate in the forming annealing device; The thickness of the glass substrate is the target molding thickness.

[0110] Specifically, the formula for the similarity relationship of the thickness forming region length is:

[0111]

[0112] in, To design the thickness forming zone length of the forming annealing device; For reference, the thickness forming zone length of the forming annealing device; Target forming thickness.

[0113] Specifically, the formula for the similarity relationship of the lengths of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone is as follows:

[0114]

[0115]

[0116]

[0117]

[0118] in, , , , These refer to the lengths of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the design forming annealing apparatus; , , , These are the lengths of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the reference molding annealing apparatus, respectively. , , , These are the guide plate speed adjustment coefficients for the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the design forming annealing apparatus. Preferably, , , , .

[0119] Specifically, the formula for the similarity relationship of heating power between the pre-annealing zone, the soaking zone, the annealing zone, and the subsequent annealing zone is as follows:

[0120]

[0121]

[0122]

[0123]

[0124] in, , , , These refer to the heating power of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the design forming annealing apparatus; , , , These are the heating powers of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the reference molding annealing apparatus, respectively.

[0125] Specifically, based on the above similarity relationship, the total length of the glass substrate overflow forming annealing apparatus is... for:

[0126] .

[0127] The continuous and gradual change in the physical properties of glass during its cooling from a molten state to room temperature is the sole basis for annealing theory. However, the traditional theoretical framework of "melt (viscous) → viscoplastic body (viscoelastic) → elastomer" does not fully reveal the complete picture of this complex process. Research has found that glass undergoes several different glass states during its cooling process, including a viscous state (free flow, high viscosity-plasticity), a viscoelastic state (elastoplastic, initial elastomer state, subrigid body), and finally enters an elastic state (rigid body). Therefore, only by introducing a comprehensive perspective of "temperature difference, structural difference, and thermal stress" to analyze the annealing mechanism of glass can a more comprehensive and in-depth theoretical basis be provided for annealing theory.

[0128] Based on new theoretical research findings, glass substrate annealing is classified into six basic fluid characteristics:

[0129] 1. Free-flowing melt stage, viscosity range: The melting overflow zone corresponding to the melt overflow downflow method: from melting, clarifying, homogenizing to the overflow brick tip (root). Thermodynamic and kinetic characteristics: free flow. It is the melting viscosity of glass; It is close to the viscosity of the overflow brick tip glass melt.

[0130] 2. High-viscosity plastic stage, viscosity range: The thickness formation zone corresponding to the melt overflow down-draw method: from the tip (root) of the overflow brick through the thickness zone to the theoretical annealing point. Thermodynamic and kinetic characteristics: high displacement activity, rapid structural adjustment. It has a viscosity close to that of the glass melt at the tip of the overflow brick; It is the starting viscosity and relaxation time for theoretical glass annealing. Start from 0 to change (Approximately a few seconds). Despite the temperature difference, no structural difference is generated, and no stress field exists in the glass.

[0131] 3. Elastic-plastic stage, viscosity range: (Avoid deformation annealing; optimal annealing state). Pre-annealing zone corresponding to the melt overflow pull-down method: from the theoretical annealing point to the expansion and softening point (deformation point). Thermodynamic and kinetic characteristics: structural group displacement and molecular displacement. Narrowly defined stress relaxation is a typical characteristic of this stage; structural adjustment reduces structural differences. Plus the implicit structural differences Equal to the structural difference caused by temperature difference The structural difference is 0, which means that the stress dissipation effect is complete.

[0132] 4. Viscosity range in the initial state of the elastomer: (Avoid deformation annealing; suboptimal annealing condition). Corresponding to the glass transition region (GTTR) of the melt overflow pull-down method: from the expansion softening point (deformation point) to the actual annealing point. Thermodynamic and kinetic characteristics: structural group displacements tend towards molecular displacements. A sharp increase in viscosity leads to a sharp decrease in displacement activity and differential deformation activity. Since thermal conductivity decreases slightly with temperature drop, the temperature difference increases accordingly, even if the cooling rate remains constant. Instead of decreasing, it increased. Approximately At that time, the remaining structure, except for some implicit stresses, showed a measurable proportion of exposed thermal stresses. The narrow definition of stress relaxation was eventually replaced by the broad definition, with internal stresses being partially implicit and partially explicit, i.e., an incomplete stress dissipation effect.

[0133] 5. Transition to a fully elastic (subrigid) stage, viscosity range: (Non-deformation annealing, worst annealed state). The stress control zone corresponding to the melt overflow pull-down method: from the actual annealing upper limit to the theoretical annealing lower limit. Thermodynamic and kinetic characteristics: molecular displacement. Displacement and differential deformation tend to decrease as viscosity increases further. , Although it has not yet reached the point where stress and strain are directly proportional and follow Hooke's Law, it already exhibits characteristics of a subrigid body.

[0134] 6. Perfectly elastic (rigid) body stage, viscosity range: (Subsequent annealing). The subsequent annealing zone corresponding to the melt overflow pull-down method: theoretical annealing lower limit minus actual annealing lower limit. Below room temperature. Thermodynamic and kinetic characteristics: particle vibration. Viscosity: hour, , This refers to the annihilation of the generalized stress relaxation phenomenon, where stress and strain are directly proportional and follow Hooke's Law. All structural differences are revealed until homogeneous room temperature, at which point they no longer change, representing permanent stress. Viscosity greater than... At this temperature, the temperature difference only produces a reversible structural difference because there is no differential deformation; this structural difference is fully exposed, and the resulting thermal stress that disappears as the temperature homogenizes is called temporary stress. Before the temporary stress disappears, it superimposes with the permanent stress at the point where the vectors coincide. When a single stress or superimposed stress exceeds the tensile strength of the glass, it will crack.

[0135] The annealing stage is a process of preventing deformation during annealing ( ) and non-deformation annealing ( It consists of two smaller stages. Based on annealing efficiency, it is divided into three annealing states, each corresponding to one of the three physical property stages. This is the theoretical starting viscosity for annealing. This is the actual initial viscosity after annealing. Annealing stage ( Irreversible structural differences caused by temperature variations The structural difference is related to viscosity, duration of exposure, and temperature difference; structural adjustment reduces the structural difference ( The remaining structural difference is related to viscosity and time, but not to the magnitude of the temperature difference; It is only related to viscosity, and has nothing to do with the time or temperature difference. Viscosity determines whether the remaining structural difference is partially or completely implicit.

[0136] Exposed (measurable) structural differences (residual structural differences) The corresponding stresses include thermal stress (caused by temperature difference) and expansion stress (caused by expansion difference). Temperature difference generates viscosity difference, expansion difference, and density difference, reflecting the irreversible structural differences resulting from structural adjustments. The corresponding stresses include thermal stress (caused by temperature difference) and expansion stress (caused by expansion difference). As viscosity increases dramatically, thermal conductivity decreases slightly with temperature drop, causing thermal stress to increase accordingly. Even with a constant cooling rate, irreversible structural differences increase rather than decrease. Structural differences reduced by structural adjustments caused by structural groups or molecular displacements (…) As viscosity increases dramatically, displacement activity decreases sharply, significantly reducing the structural difference. The structural difference implied (undetectable) by differential deformation (residual structural difference) Unlike structural adjustment, it does not reduce structural differences at all; it is only a temporary, implicit effect. As viscosity increases dramatically, the differential deformation activity decreases sharply, thus significantly reducing the structural difference.

[0137] The present invention provides a design method for an overflow forming annealing apparatus for glass substrates with increased flow rate, overcoming the misconceptions of traditional theories. This achieves a more precise, efficient, and cost-effective overflow forming annealing apparatus design, ensuring quality control in terms of thickness, compression, stress, warpage, and other forming parameters. By rapidly cooling to reduce the viscous region distance, extending the vitrification and annealing time, and appropriately reducing the elastic region interval, the physical shell of the forming apparatus remains unchanged while improving quality indicators such as stress and compression. Specifically, in the viscous region, radiation dominates the cooling curve, and changes in cooling method or time have almost no effect on compression; therefore, a fixed length can be maintained, and the thickness formation zone can be shortened through rapid cooling. In the viscoelastic region, compression, residual stress, and shape are essentially determined; the length of this region is closely related to factors such as flow rate, viscosity, and strain point. In the elastic region, as a non-value-adding region, temporary stress caused by uneven cooling should be minimized.

[0138] The present invention will be further described in detail below with reference to the embodiments.

[0139] A design method for an overflow forming annealing device with improved yield includes the following steps:

[0140] 1. Obtain the geometric parameters of a mature glass substrate overflow forming annealing apparatus, including the length of the thickness forming zone. Length of the pre-annealing zone Length of the heat spreader Length of the annealing zone and the length of the subsequent annealing zone ; Obtain specific parameters, including extraction amount Overflow brick overflow surface width Overflow brick slope height Glass substrate specifications and width Average edge width of glass substrate Heating power of the pre-annealing zone heater Heating power of the heat spreader heater Heating power of the annealing zone heater and the heating power of the heater in the subsequent annealing zone .

[0141] II. Obtain common parameters for mature glass substrate overflow forming annealing apparatus and target design forming annealing apparatus, including the half angle of the overflow brick bevel. Density of glass substrate Viscosity at the base of the overflow brick .

[0142] III. Setting the target design for the extraction volume of the forming annealing device Overflow brick overflow surface width Overflow brick slope height Glass substrate specifications and width Average edge width of glass substrate and the target forming thickness of the glass substrate .

[0143] IV. Calculate the length of the thickness formation zone:

[0144] The calculation method for the thickness forming zone length of the overflow forming annealing apparatus includes the following steps:

[0145] L1 calculates the lead-out length per unit length:

[0146]

[0147]

[0148] L2 Calculates the thickness of the glass ribbon leaving the base of the overflow brick in the forming annealing device:

[0149]

[0150]

[0151] in, It is the acceleration due to gravity;

[0152] L3 Calculate the length of the thickness forming zone of the forming annealing device. :

[0153]

[0154] V. Calculate the length of each annealing zone in the design of the forming annealing apparatus:

[0155] The method for calculating the length of each annealing zone in an overflow forming annealing apparatus includes the following steps:

[0156] S1 Calculates the width of the lead plate:

[0157]

[0158]

[0159] in, , , .

[0160] S2 calculates the critical contraction width of the drainage plate:

[0161]

[0162]

[0163] S3 Calculate the speed of the guide plate in the forming annealing device:

[0164]

[0165]

[0166] S4 Calculate the length of each annealing zone in the design forming annealing apparatus. , , , :

[0167]

[0168]

[0169]

[0170]

[0171] in, , , , .

[0172] S5 Calculate the total length of the forming annealing device. :

[0173]

[0174] VI. Calculate the heating power of each annealing zone in the design of the forming annealing apparatus:

[0175]

[0176]

[0177]

[0178]

[0179] The moving glass ribbon from temperature Cool to Its heat loss rate (unit: )for:

[0180]

[0181] in, This refers to the amount of glass substrate lead-out; It is the specific heat capacity of glass; ; The theoretical annealing initiation temperature of the glass substrate; Thickness Formation Zone The temperature difference.

[0182] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method of designing a draw height boosting overflow mold annealing apparatus, characterized by, The method comprises the following steps: Step one, selecting a mature glass substrate overflow forming and annealing device as a reference forming and annealing device, respectively obtaining the geometric structure parameters, specific parameters and common parameters of the reference forming and annealing device, the geometric structure parameters including the length of the thickness forming area of the reference device , the length of the pre-annealing area , the length of the soaking area , the length of the annealing area and the length of the subsequent annealing area ; the specific parameters include the heating power of the pre-annealing area heater , the heating power of the soaking area heater , the heating power of the annealing area heater and the heating power of the subsequent annealing area heater , the lead-out amount , the overflow brick overflow surface width , the glass substrate specification width , the average edge plate width of the glass substrate and the overflow brick bevel height ; the common parameters include the overflow brick bevel half angle , the density of the glass substrate and the viscosity of the overflow brick root ; Step two, according to the parameters obtained in step one, calculate the unit length of the reference forming and annealing device , critical contraction width of the flow guide plate and the width of the guide plate ; Step three, calculating the thickness of the glass ribbon leaving the root of the isopipe of the reference forming and annealing apparatus based on the parameters obtained in step one and the parameters calculated in step two and the speed of the tab ; Step four, the length of the thickness forming zone is determined according to the drawing amount per unit length and the thickness of the glass ribbon leaving the root of the overflow brick , the length similarity relationship of the thickness forming zone is established; the length similarity relationship of the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone is respectively established according to the obtained length of the pre-annealing zone , the length of the soaking zone , the length of the annealing zone , the length of the subsequent annealing zone and the speed of the drawing plate ; the heating power similarity relationship of the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone is established according to the obtained heating power of the pre-annealing zone heater , the heating power of the soaking zone heater , the heating power of the annealing zone heater and the heating power of the subsequent annealing zone heater ; The length similarity relationship of the thickness forming area, the length similarity relationship of the pre-annealing area, the soaking area, the annealing area and the subsequent annealing area, and the heating power similarity relationship of the pre-annealing area, the soaking area, the annealing area and the subsequent annealing area are used to complete the design of the drawing amount improving overflow forming annealing device; The length similarity relationship of the thickness forming area is specifically as follows: wherein, is the glass substrate gauge thickness, i.e., the target formed thickness; is the designed unit length draw of the forming lehr, specifically: The thickness of the glass ribbon leaving the root of the isopipe for a design- in-place annealing apparatus is specifically: length of the thickness forming zone of the design forming annealing device, the draw of the design forming annealing device, the width of the overflow face of the overflow brick of the design forming annealing device; g is the acceleration of gravity; The length similarity relationship of the pre-annealing area is specifically as follows: The length similarity relationship of the soaking area is specifically as follows: The length similarity relationship of the annealing area is specifically as follows: The length similarity relationship of the subsequent annealing area is specifically as follows: wherein, The speed of the guide plate of the designed forming annealing device is specifically: To design the width of the guide plate of the designed forming annealing device, specifically: a glass substrate specification width for a design forming annealing apparatus, a glass substrate average edge panel width for a design forming annealing apparatus, the glass substrate average edge panel width ranging from 150 to 175 mm; an edge panel cutting factor, ; The critical contraction width of the flow guide plate designed for the forming annealing device is specifically: To design the overflow slope height of the overflow brick; , , , These refer to the lengths of the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone in the design forming annealing apparatus. , , , These are the guide plate speed adjustment coefficients for the pre-annealing zone, soaking zone, annealing zone, and subsequent annealing zone of the design forming annealing apparatus, respectively. , , , , The design guide plate width for designing the forming annealing device; The heating power similarity relationship of the pre-annealing area heater is specifically as follows: The heating power similarity relationship of the soaking area heater is specifically as follows: The heating power similarity relationship of the annealing area heater is specifically as follows: The heating power similarity relationship of the subsequent annealing area heater is specifically as follows: wherein, , , , are the heating powers of the pre-annealing zone, the soaking zone, the annealing zone and the subsequent annealing zone heaters of the designed-shape annealing device, respectively.

2. A method of designing a draw height boosting overflow mold annealing apparatus according to claim 1, wherein The reference forming and annealing device has a unit length of the lead-out amount According to the obtained lead-out amount And the width of the overflow brick overflow surface The calculation formula is: 。 3. A method of designing a draw height boosting overflow mold annealing apparatus according to claim 2, wherein Critical contraction width of the flow guide plate of the reference molding and annealing device Width of the overflow face of the overflow brick obtained according to the obtained overflow brick overflow face And the height of the inclined surface of the overflow brick The calculation formula is: 。 4. A method of designing a draw height boosting overflow mold annealing apparatus according to claim 3, wherein The reference forming and annealing device's guide plate width To calculate the glass substrate specification width And the glass substrate average edge plate width The calculation is as follows: Among them, the average edge width of the glass substrate It is 150~175 mm.

5. A method of designing a draw height boosting overflow mold annealing apparatus according to claim 4, wherein Thickness of the glass ribbon exiting the root of the isopipe of the reference forming and annealing apparatus To obtain the half angle of the isopipe bevel Density of the glass substrate Viscosity of the root of the isopipe And the draw per length The calculation formula is: 。 6. A method of designing a draw height boosting overflow mold annealing apparatus according to claim 5, wherein The strip speed of the reference forming and annealing apparatus To obtain the density of the glass substrate The overflow width of the overflow brick The width of the glass substrate specification The strip width And the critical shrinkage width of the strip The calculation formula is: 。 7. A draw height increasing overflow mold annealing apparatus characterized by A drawing amount improving overflow forming annealing device is designed and manufactured based on the design method of any one of claims 1-6.

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