Method and system for designing a stirring system in manufacturing glass substrates

Abstract

The present invention discloses a design method and system for a stirring system in the manufacture of glass substrates, which belongs to the field of glass substrate manufacture. The method obtains parameters such as the sweep height of the stirrer blade, withdrawal amount, stirring tank inner diameter, stirrer blade diameter, stirrer output, stirrer rotation speed and stirrer torque in the reference stirring system, respectively establishes shear stress equivalence relationship and stirring effect equivalence relationship, and calculates the actual stirring tank inner diameter, actual stirrer blade diameter and actual stirrer blade sweep height in the actual stirring system according to the corresponding relationship, thereby completing the design of the actual stirring system. The method establishes the design standard for the stirrer blade sweep height, stirring blade diameter and stirring tank inner diameter, and can simultaneously optimize the stirring shaft creep and system cost, and meet the technical requirements of high efficiency and high uniform stirring effect.

Description

[Technical field]

[0001] The present invention relates to the field of glass substrate manufacturing, and more particularly to a method and system for designing agitation systems in the manufacture of glass substrates. [Background technology]

[0002] Glass substrates used in the field of flat panel display manufacturing such as general TFT-LCD (thin film transistor display) and PDP (plasma display) are manufactured by the overflow downdraw method, which is produced by supplying glass liquid melted in a glass melting furnace to a molten overflow downdraw molding device in the molding process. The chemical uniformity and thermal uniformity of glass are important factors to judge whether the glass forming operation is good or not. In the production of liquid crystal substrate glass, the main factor that adversely affects the profits and production volume of the company is glass defects, and the main quality defects of substrate glass are bubbles, knots, striae, etc. Among them, bubbles are divided into bubbles caused by poor fining, secondary bubbles, and mixed bubbles, and knots are mainly platinum-rhodium knots, and striae are mainly caused by the unevenness of the components in the molten glass liquid. In the production of liquid crystal substrate glass, in order to homogenize the components in the molten glass liquid, the stirring device in the passage is an effective means to improve the uniformity of the glass. In the process of molten glass flowing from the top to the bottom of the stirring chamber, the blade plays the role of mixing the molten glass. The stirrer and stir chamber are typically fabricated from a refractory metal to withstand the high temperatures and chemical attack of the glass.

[0003] The volatile oxides in the glass stirrer may be formed by any element present in the glass and the stirrer. The free surface of the glass refers to the surface of the glass melt exposed to the atmosphere in the stirrer. The atmosphere above the free surface of the glass (wherein the atmosphere contains one or all of the above volatile substances) is hotter than the atmosphere outside the stirrer and therefore has a natural tendency to flow upwards through any opening (e.g., the annular space between the stirrer shaft and the stirring vessel lid). The stirrer shaft gets colder as the distance between the stirrer shaft and the free surface of the glass melt increases, and when the temperature drops below the dew point of the above oxides, the volatile oxides contained in the atmosphere of the stirrer can condense on the surface of the shaft. When the condensates reach a critical size, they can break off and enter the glass, forming inclusions or bubble defects in the glass product. It has been proven that heating the shaft above the free surface of the glass is only partially effective in reducing particulate impurities in the glass melt, and only leads to stratification due to condensation. Improving the stirring process is a more effective way to reduce platinum group defects.

[0004] Generally, glass stirring systems are designed according to the highest shear stress, so that they can be consistent with a reasonable stirrer service life. In fact, in normal designs, such systems can generate high shear stress even when operating at low speeds. The high melting point metals (e.g. platinum group metals and their alloys) often used in manufacturing stirring systems are expensive, so it is desirable to achieve maximum stirring with the smallest stirring system. In general, the shear stress can be increased by increasing the blade speed and decreasing the gap (bonding distance) between the stirrer blade and the stirring chamber wall to lower the glass temperature, or by combining these measures. In physical experiments, the evaluation of the stirring effect is a difficulty. Researchers often intuitively show the stirring effect by dyeing simulated fluids in tests, but such methods cannot quantitatively compare experimental data, or experimenters evaluate the stirring effect by measuring the local density of the finished product, but such methods cannot compare the density before and after stirring, and there is a certain error. Since recent years, in order to improve the efficiency of the production line, glass substrates have become larger and larger in size, and the drawing amount is becoming higher and higher. In order to meet the needs of higher generation and higher withdrawal rate, the design of the stirring system becomes one of the core elements of the overall design of the glass substrate manufacturing equipment.

[0005] As can be seen from the above, it is difficult to find a balance between shear stress and mixing effect by the conventional design method of the mixing system, and therefore the technical requirements of high efficiency and high uniform mixing effect cannot be met. Summary of the Invention [Problem to be solved by the invention]

[0006] In order to solve the above technical problems, the present invention provides a design method and system for a stirring system in the production of glass substrates, which can meet the technical requirements of high efficiency and high uniform stirring effect, thereby meeting the needs of higher generation and higher withdrawal amount. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention uses the following technical solutions.

[0008] 1. A method for designing a stirring system in manufacturing a glass substrate, comprising: Selecting a standard stirring system as a reference stirring system, and obtaining parameters such as the sweep height of the stirrer blade, the withdrawal amount, the inner diameter of the stirring tank, the diameter of the stirrer blade, the stirrer output, the stirrer rotation speed and the stirrer torque of the reference stirring system; Establishing a shear stress equivalence relationship based on the inner diameter of the stirred tank, the diameter of the stirrer blade, and the stirrer rotation speed; Establishing an agitation effect equivalence relationship based on the agitator blade sweep height, withdrawal amount, agitator blade diameter, agitator power, agitator rotation speed and agitator torque; and calculating an actual stirring vessel inner diameter, an actual stirrer blade diameter, and an actual stirrer blade sweep height in the actual stirring system based on the reference stirring system, the shear stress equivalence relationship, and the stirring effect equivalence relationship, thereby completing the design of the actual stirring system.

[0009] Furthermore, the specific formula of the shear stress equivalence relationship is: TIFF2025501826000002.tif1226, where N is the actual agitator rotation speed and D Y is the actual diameter of the agitator blade, and D B is the actual inner diameter of the mixing vessel, and N 0 is the agitator rotation speed, and D Y0 is the diameter of the agitator blade, and D B0 is the inner diameter of the mixing vessel.

[0010] Furthermore, the shear stress τ according to the shear stress equivalence relationship is Satisfy the relationship of TIFF2025501826000003.tif1225, where η is the viscosity of the glass, and C is the gap between the agitator blade and the inner wall of the agitation vessel.

[0011] Furthermore, the gap C between the agitator blade and the inner wall of the mixing vessel is Satisfies the relationship TIFF2025501826000004.tif1217.

[0012] Furthermore, the specific formula of the stirring effect equivalence relationship is: TIFF2025501826000005.tif1235 or TIFF2025501826000006.tif1229, where T is the actual agitator torque, P is the actual agitator power, H is the actual agitator blade sweep height, Q is the actual withdrawal amount, and T 0 is the agitator torque, and P 0 is the agitator output, and H 0 is the swept height of the agitator blade, and Q 0 is the withdrawal amount.

[0013] Furthermore, the stirring effect E according to the stirring effect equivalence relationship is as follows: Satisfies the relationship TIFF2025501826000007.tif1225.

[0014] Furthermore, the calculation formula for the actual sweep height H of the agitator blade is: The file is TIFF2025501826000008.tif1221.

[0015] Furthermore, the actual diameter D of the agitator blade Y The calculation formula is: The file is TIFF2025501826000009.tif1255.

[0016] Furthermore, the actual inner diameter of the mixing vessel D B The calculation formula is: The file is TIFF2025501826000010.tif1253.

[0017] A design system for a stirring system in the manufacture of a glass substrate for implementing steps of the design method for a stirring system in the manufacture of a glass substrate, an acquisition module for selecting the standard stirring system as a reference stirring system and acquiring parameters such as the sweep height of the stirrer blade, the withdrawal amount, the inner diameter of the stirring vessel, the diameter of the stirrer blade, the stirrer output, the stirrer rotation speed and the stirrer torque of the reference stirring system; a shear stress module for establishing a shear stress equivalence relationship based on the inner diameter of the mixing vessel, the diameter of the agitator blade, and the agitator rotation speed; a stirring effect module for establishing a stirring effect equivalence relationship based on the agitator blade sweep height, withdrawal amount, agitator blade diameter, agitator power, agitator rotation speed, and agitator torque; and a design module for calculating an actual inner diameter of the stirring vessel, an actual diameter of the stirrer blade, and an actual sweep height of the stirrer blade in the actual stirring system based on the reference stirring system, the shear stress equivalence relationship, and the stirring effect equivalence relationship, to complete the design of the actual stirring system. Effect of the Invention

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The present invention provides a design method for a stirring system in the manufacture of glass substrates. The method obtains parameters such as the stirrer blade sweep height, withdrawal amount, stirring tank inner diameter, stirrer blade diameter, stirrer power, stirrer rotation speed and stirrer torque in the reference stirring system, respectively establishes shear stress equivalence relationship and stirring effect equivalence relationship, and calculates the actual stirring tank inner diameter, actual stirrer blade diameter and actual stirrer blade sweep height in the actual stirring system according to the corresponding relationship, thereby completing the design of the actual stirring system. The method establishes the design standard for the stirrer blade sweep height, stirrer blade diameter and stirring tank inner diameter based on the reference stirring system and the shear stress and stirring effect equivalence relationship, and can balance the stirring shaft creep and system cost optimization, and meet the technical requirements of high efficiency and high uniform stirring effect, thereby meeting the needs of higher generation and higher withdrawal amount.

[0020] The present invention further provides a design system for a stirring system in the manufacture of glass substrates, which can realize the steps of the above design method and meet the needs of higher generation and higher withdrawal amount. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a structural schematic diagram of a geometric model of a mixing system according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the cross-sectional design dimensions of a stirring system according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram of the simulated stirring effect of the stirring system according to an embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart of a method for designing a stirring system in the manufacture of glass substrates according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present invention provides a method for designing a stirring system in the manufacture of glass substrates, as shown in FIG. Selecting a standard stirring system as a reference stirring system, and obtaining parameters such as the sweep height of the stirrer blade, the withdrawal amount, the inner diameter of the stirring tank, the diameter of the stirrer blade, the stirrer output, the stirrer rotation speed and the stirrer torque of the reference stirring system; Establishing a shear stress equivalence relationship based on the inner diameter of the stirred tank, the diameter of the stirrer blade, and the stirrer rotation speed; Establishing an agitation effect equivalence relationship based on the agitator blade sweep height, withdrawal amount, agitator blade diameter, agitator power, agitator rotation speed and agitator torque; and calculating an actual stirring vessel inner diameter, an actual stirrer blade diameter, and an actual stirrer blade sweep height in the actual stirring system based on the reference stirring system, the shear stress equivalence relationship, and the stirring effect equivalence relationship, thereby completing the design of the actual stirring system.

[0023] Specifically, the specific formula for the shear stress equivalence relationship is: TIFF2025501826000011.tif1226, where N is the actual agitator rotation speed and D Y is the actual diameter of the agitator blade, and D B is the actual inner diameter of the mixing vessel, and N 0 is the agitator rotation speed, and D Y0 is the diameter of the agitator blade, and D B0 is the inner diameter of the mixing vessel.

[0024] In particular, the shear stress τ according to the shear stress equivalence relation is Satisfying the relationship of TIFF2025501826000012.tif1225, where η is the viscosity of the glass, and C is the gap between the agitator blade and the inner wall of the agitation vessel.

[0025] The gap C between the agitator blade and the inner wall of the agitation vessel is Satisfy the relationship of TIFF2025501826000013.tif1217, Specifically, the specific formula for the stirring effect equivalence relationship is: TIFF2025501826000014.tif1235 or TIFF2025501826000015.tif1229, where T is the actual agitator torque, P is the actual agitator power, H is the actual agitator blade sweep height, Q is the actual withdrawal amount, and T 0 is the agitator torque, and P 0 is the agitator output, and H 0 is the swept height of the agitator blade, and Q 0 is the withdrawal amount.

[0026] In particular, the mixing effect E according to the mixing effect equivalence relationship is Satisfies the relationship TIFF2025501826000016.tif1225.

[0027] The formula for calculating the actual sweep height H of the agitator blade is: The file is TIFF2025501826000017.tif1221.

[0028] Actual agitator blade diameter D Y The calculation formula is: The file is TIFF2025501826000018.tif1255.

[0029] The actual inner diameter of the mixing vessel D B The calculation formula is: The file is TIFF2025501826000019.tif1253.

[0030] The present invention further provides a design system for a stirring system in the manufacture of glass substrates, the design system comprising an acquisition module, a determination module, a shear stress module, a stirring effect module and a design module, the acquisition module is for selecting a standard stirring system as a reference stirring system and respectively acquiring parameters such as the stirrer blade sweep height, withdrawal amount, stirring tank inner diameter, stirrer blade diameter, stirrer power, stirrer rotation speed and stirrer torque in the reference stirring system, the shear stress module is for establishing a shear stress equivalence relationship based on the stirring tank inner diameter, the stirrer blade diameter and the stirrer rotation speed, the stirring effect module is for establishing a stirring effect equivalence relationship based on the stirrer blade sweep height, withdrawal amount, stirrer blade diameter, stirrer power, stirrer rotation speed and stirrer torque, and the design module is for calculating the actual stirring tank inner diameter, actual stirrer blade diameter and actual stirrer blade sweep height in the actual stirring system based on the reference stirring system, the shear stress equivalence relationship and the stirring effect equivalence relationship to complete the design of the actual stirring system.

[0031] Working Example As shown in FIG. 1, the stirring system comprises an inlet end 1, an outlet end 2, a stirring tank 3, a stirring shaft 5 and a number of stirring blades 4, the stirring tank 3 is a cylindrical hollow, the inlet end 1 is installed at the upper part of the side wall of the stirring tank 3, the outlet end 2 is installed at the bottom of the stirring tank 3, the stirring shaft 5 is inserted and installed at the top of the stirring tank 3, and the plurality of stirring blades 4 are installed in the stirring tank 3 along the shaft body of the stirring shaft 5.

[0032] In the manufacture of glass substrates, the stirring function of the platinum passage is to make the non-uniform molten glass liquid more uniform, and reduce the striae defects of the finished glass substrate. Glass homogenization includes chemical homogeneity and thermal homogeneity. Various chemical phase striae in glass furnaces are caused by the melting of refractory materials, separation of molten metal, volatilization of the glass surface, and temperature differences during the melting process. There are differences in color or refractive index. In the manufacture of glass, platinum-rhodium defects with dimensions smaller than 50 μm are caused by corrosion of the stirrer and the wall of the stirring vessel due to the viscous shear stress of the stirrer. Here, the homogenization mechanism is as follows: (1) by applying shear stress to the glass melt, the non-uniform phase is pulled into thin striae; (2) by cutting the striae into short pieces by the plane of the stirrer blade perpendicular to the flow direction of the glass melt; and (3) by dispersing the pieces by making the glass flow radially by the blade shape that pushes the glass melt perpendicular to the overall flow direction.

[0033] As shown in FIG. 2, H is the sweep height (also called the sweep range) of the agitator blade in the actual mixing system, and D B is the inner diameter of the mixing vessel in the actual mixing system, and D Y is the stirring diameter of the stirrer blade in the actual stirring system. The smallest stirring system can achieve maximum stirring, thereby reducing the cost of precious metals such as platinum and rhodium. By harmonizing the relationship between the stirrer speed, the stirrer / stirring vessel geometry, and the viscosity of the glass, the shear stress can be reduced to below the level at which unacceptable platinum and rhodium defects form, while maintaining the stirring efficiency and flow rate at a level that can only be achieved with high shear stress, thus achieving the goal of harmonizing the contradictions between shear stress, flow rate, and stirring efficiency.

[0034] Here, the formula for calculating the actual sweep height H of the agitator blade is: The file is TIFF2025501826000020.tif1221.

[0035] Actual agitator blade diameter D Y The calculation formula is: The file is TIFF2025501826000021.tif1255.

[0036] Actual inner diameter of mixing vessel D B The calculation formula is: The file is TIFF2025501826000022.tif1253.

[0037] N is the actual agitator rotation speed, and D Y is the actual diameter of the agitator blade, and D B is the actual inner diameter of the mixing vessel, and N 0 is the agitator rotation speed, and D Y0 is the diameter of the agitator blade, and D B0 is the inner diameter of the mixing vessel, and H 0 is the swept height of the agitator blade in the reference stirring system, T is the actual agitator torque, P is the actual agitator power, H is the actual swept height of the agitator blade, Q is the actual withdrawal amount, and T 0 is the agitator torque, and P 0 is the agitator output, and H 0 is the swept height of the agitator blade, and Q 0 is the withdrawal amount.

[0038] A dedicated fluid dynamics numerical analysis software (e.g., Ansys-Fluent) is used to perform a coupled calculation of thermal field and flow for the platinum passage stirring system, as shown in Figure 3. The flow field and temperature field of the molten glass liquid in the stirring tank are studied, and the optimal rotation speed of the stirrer is obtained by analyzing the flow state of the glass liquid in the stirring tank and the law of homogenization effect.

[0039] A suitable (but not too high) shear stress ensures low platinum defect rates and high mixing (homogenization) efficiency. The aim of mixing is to achieve adequate homogenization at a given flow rate Q, and the reduction of the shear stress should not be at the expense of the mixing efficiency, and can extend the service life of the mixing system by maximally reducing corrosion. At a given flow rate Q, to keep the mixing efficiency unchanged and to reduce the shear stress, it is generally necessary to increase the stirrer diameter or the stirring volume to keep H constant. In practice, this means increasing the residence time, which can also be maintained to keep the glass melt sufficiently homogenized even at low stirring rotation speeds. The torque T should be kept low enough to avoid significant creep of the stirrer shaft due to torque stresses at the stirring temperature.

[0040] The specific implementation process is as follows:

[0041] When the stirring system according to this embodiment is in operation, the stirrer is driven by the transmission mechanism to rotate at a constant speed at a set rotation speed, thereby stirring the molten glass liquid that has entered the stirring tank 3 through the inlet end 1. Since the molten glass liquid itself has thermal conductivity, there is a possibility that the temperature of the molten glass liquid at the downstream of the stirring tank 3 has already reached the same temperature.

[0042] The reference mixing system is a mixing vessel with an inner diameter D B0 = 360mm, stirring blade diameter D Y0 = 300mm, Sweep height of the agitator blade H 0 = 610 mm, agitator rotation speed N 0 = 8 rpm, withdrawal amount Q 0 =22T / Day.

[0043] The actual stirring system is designed such that the actual stirrer rotation speed N=8 rpm and the actual withdrawal rate Q=28 T / Day.

[0044] TIFF2025501826000023.tif1214, and assuming that the same motor and rated output P as the reference mixing system are used, and the same rotation speed N as the reference mixing system are used, the inner diameter D of the mixing vessel is B = 460.1 mm, maximum diameter of stirring blade D Y = 383.41 mm, and the sweep height of the agitator blades H = 732 mm.

[0045] To verify the equivalence of shear stresses, TIFF2025501826000024.tif1234 is calculated, To verify the equivalence of the mixing effect, TIFF2025501826000025.tif1256 is calculated, According to the method of this embodiment, the designed actual stirring system has the same stirring effect as the reference stirring system, balances the stirring shaft creep and system cost optimization, and meets the technical requirements of high efficiency and high uniform stirring effect for the needs of higher generation and higher withdrawal amount.

[0046] The above examples are merely examples of embodiments that can realize the technical solutions of the present invention, and the scope of the claims of the present invention is not limited to these examples, but also includes any modifications, substitutions, and other embodiments that may be easily thought of by a person skilled in the art within the technical scope disclosed in the present invention. [Explanation of symbols]

[0047] 1 Inlet end 2 Outlet end 3 Mixing tank 4 Stirring blade 5 Agitation shaft

Claims

1. 1. A method for designing a stirring system in manufacturing a glass substrate, comprising: Selecting a standard stirring system as a reference stirring system, and obtaining parameters such as the sweep height of the stirrer blade, the withdrawal amount, the inner diameter of the stirring tank, the diameter of the stirrer blade, the stirrer output, the stirrer rotation speed and the stirrer torque in the reference stirring system; Establishing a shear stress equivalence relationship based on the inner diameter of the stirred tank, the diameter of the stirrer blade, and the stirrer rotation speed; Establishing an agitation effect equivalence relationship based on the agitator blade sweep height, withdrawal amount, agitator blade diameter, agitator power, agitator rotation speed and agitator torque; and calculating an actual stirring vessel inner diameter, an actual stirrer blade diameter, and an actual stirrer blade sweep height in the actual stirring system based on the reference stirring system, the shear stress equivalence relationship, and the stirring effect equivalence relationship, thereby completing the design of the actual stirring system.

2. The specific formula of the shear stress equivalence relationship is: and where N is the actual agitator rotation speed and D Ｙ is the actual agitator blade diameter, D Ｂ is the actual inner diameter of the mixing vessel, and N ０ is the agitator rotation speed, D Ｙ０ is the diameter of the agitator blade, D Ｂ０ The method for designing a stirring system in manufacturing glass substrates according to claim 1, characterized in that

3. The shear stress τ according to the shear stress equivalence relationship is Satisfying the relationship, 3. The method for designing an agitation system in the manufacture of glass substrates according to claim 2, wherein η is the viscosity of the glass, and C is the gap between the agitator blade and the inner wall of the agitation vessel.

4. The gap C between the agitator blade and the inner wall of the agitation tank is 4. The method for designing a stirring system in manufacturing a glass substrate according to claim 3, wherein the following relationship is satisfied:

5. The specific formula of the stirring effect equivalence relationship is: Or, and where T is the actual agitator torque, P is the actual agitator power, H is the actual agitator blade sweep height, Q is the actual withdrawal amount, and T ０ is the agitator torque, P ０ is the agitator output, and H ０ is the sweep height of the agitator blade, and Q ０ The method for designing a stirring system in manufacturing a glass substrate according to claim 4, wherein the amount of pulling is a pulling amount.

6. The stirring effect E according to the stirring effect equivalence relationship is 6. The method for designing a stirring system in manufacturing a glass substrate according to claim 5, wherein the following relationship is satisfied:

7. The calculation formula for the actual agitator blade sweep height H is: The method for designing a stirring system in manufacturing a glass substrate according to claim 6,

8. The actual diameter D of the agitator blade Ｙ The calculation formula is: The method for designing a stirring system in manufacturing a glass substrate according to claim 7,

9. The actual inner diameter D of the mixing vessel Ｂ The calculation formula is: The method for designing a stirring system in manufacturing a glass substrate according to claim 8,

10. A design system for a stirring system in the manufacture of a glass substrate for implementing the steps of the design method for a stirring system in the manufacture of a glass substrate according to any one of claims 1 to 9, an acquisition module for selecting the standard stirring system as a reference stirring system and acquiring parameters such as the sweep height of the stirrer blade, the withdrawal amount, the inner diameter of the stirring vessel, the diameter of the stirrer blade, the stirrer output, the stirrer rotation speed and the stirrer torque of the reference stirring system; a shear stress module for establishing a shear stress equivalence relationship based on the inner diameter of the mixing vessel, the diameter of the agitator blade, and the agitator rotation speed; a stirring effect module for establishing a stirring effect equivalence relationship based on the agitator blade sweep height, withdrawal amount, agitator blade diameter, agitator power, agitator rotation speed, and agitator torque; and a design module for calculating an actual stirring vessel inner diameter, an actual stirrer blade diameter, and an actual stirrer blade sweep height in the actual stirring system based on a reference stirring system, a shear stress equivalence relationship, and a stirring effect equivalence relationship, thereby completing the design of the actual stirring system.

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