Design method and system for a stirring system in glass substrate manufacturing

Abstract

The present invention discloses a design method and system for a stirring system in glass substrate manufacturing, belonging to the field of glass substrate manufacturing. This method obtains parameters such as the sweeping height of the stirrer blades, the extraction volume, the inner diameter of the stirring tank, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer of a reference stirring system, respectively establishes an equivalent relationship of shear stress and an equivalent relationship of stirring effect, and calculates the inner diameter of the actual stirring tank, the diameter of the actual stirrer blades, and the sweeping height of the actual stirrer blades of the actual stirring system according to the corresponding relationships, thereby completing the design of the actual stirring system; based on the reference stirring system and the equivalence of shear stress and stirring effect, this method establishes design benchmarks for the sweeping height of the stirring blades, the diameter of the stirring blades, and the inner diameter of the stirring tank, and at the same time takes into account the creep of the stirring shaft and the optimization of system cost, can meet the technical requirements of high-efficiency and high-homogenization stirring effect, and thus meet the needs of higher generations and higher extraction volumes.

Description

Technical Field

[0001] The present invention relates to the field of glass substrate manufacturing, and particularly to a design method and system for a stirring system in glass substrate manufacturing. Background Art

[0002] Generally, glass substrates used in the manufacturing fields of flat panel displays such as TFT-LCD (Thin Film Transistor Liquid Crystal Display) and PDP (Plasma Display Panel) are manufactured by the overflow down-draw method. In the forming process, the molten glass melted by a glass melting furnace is supplied to a molten overflow down-draw forming device for manufacturing. The chemical homogeneity and thermal homogeneity of the glass are key factors for judging whether the operation of forming the glass is good. In the production of liquid crystal substrate glass, the main factors affecting the enterprise benefits and output are glass defects. The main quality defects of the substrate glass include bubbles, stones, streaks, etc. Among them, the bubbles are divided into bubbles caused by poor clarification, secondary bubbles, entrained bubbles, etc. The stones are mainly platinum-rhodium stones, and the streaks are mainly caused by the uneven composition of the molten glass liquid. In the production of liquid crystal substrate glass, in order to homogenize the composition of the molten glass liquid, the stirring device in the channel is an effective way to improve the glass homogeneity. During the process of the molten glass flowing from the top to the bottom of the stirring chamber, the blades play a role in mixing the molten glass. In order to withstand high temperatures and the chemical corrosion of the glass, the stirrer and the stirring chamber are usually made of high-melting-point metals.

[0003] Volatile oxides in the glass stirring device can be formed by the glass and any elements present in the stirring device. The glass free surface refers to the surface of the glass melt exposed to the atmosphere inside the stirring device. Since the atmosphere above the glass free surface (the atmosphere includes one or all of the above-mentioned volatiles) is hotter than the atmosphere outside the stirring device, there is a natural flow tendency upward through any opening (such as the annular space between the stirrer shaft and the stirring container lid). As the distance between the stirrer shaft and the free surface of the glass melt increases, the stirrer shaft becomes colder. If the temperature is lower than the dew point of the above oxides, the volatile oxides contained in the atmosphere of the stirring device can condense on the surface of the shaft. When the condensate reaches a critical size, it will fall off into the glass, forming inclusions or bubble defects in the glass product. It has been proven that heating the shaft above the glass free surface only achieves partial effects in reducing particulate impurities in the glass melt, only causing layering of the condensate. Improving the stirring process is a more effective way to reduce platinum group defects.

[0004] Typically, glass stirring systems are designed according to the maximum shear stress to make it possible to be consistent with a reasonable stirrer life. In fact, in normal designs, such systems can generate high shear stress even when operating at low speeds. Due to the high cost of high melting point metals commonly used in manufacturing stirring systems (such as platinum group metals and their alloys), it is desired to achieve the maximum degree of stirring with the smallest stirring system. Generally speaking, by increasing the blade speed, reducing the gap (coupling distance) between the stirrer blades and the wall of the stirring chamber, lowering the glass temperature, or combining these measures, the shear stress can be increased. In physical experiments, it is a difficult point to measure the stirring effect. Researchers mostly use the method of dyeing the simulated fluid in the experiment to visually show the stirring effect, but this method cannot quantitatively compare experimental data; or the experimenters measure the stirring effect by measuring the local density in the finished product, but this method cannot compare the density before and after stirring and there are certain errors. In recent years, in order to improve the production line efficiency, the size of glass substrates has become larger and the drawing volume has become higher. To meet the requirements of higher generations and higher drawing volumes, the design of the stirring system is one of the cores of the design of the entire glass substrate manufacturing equipment.

[0005] It can be seen from this that in the existing design methods of stirring systems, it is difficult to find the balance point between shear stress and stirring effect, resulting in the inability to meet the technical requirements of high efficiency and high homogenization stirring effect. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a design method and system for a stirring system in glass substrate manufacturing, which can meet the technical requirements of high efficiency and high homogenization stirring effect, so as to meet the requirements of higher generations and higher drawing volumes.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A design method for a stirring system in glass substrate manufacturing, including the following steps:

[0009] Select a standard stirring system as a reference stirring system, and respectively obtain the following parameters of the reference stirring system: the sweeping height of the stirrer blades, the drawing volume, the inner diameter of the stirring tank, the diameter of the stirrer blades, the power of the stirrer, the rotational speed of the stirrer, and the torque of the stirrer;

[0010] Establish an equivalent relationship of shear stress based on the inner diameter of the stirring tank, the diameter of the stirrer blades, and the rotational speed of the stirrer;

[0011] Establish an equivalent relationship of stirring effect based on the sweeping height of the stirrer blades, the drawing volume, the diameter of the stirrer blades, the power of the stirrer, the rotational speed of the stirrer, and the torque of the stirrer;

[0012] Based on the reference stirring system, the shear stress equivalence relationship, and the stirring effect equivalence relationship, the actual inner diameter of the stirring tank, the actual diameter of the stirrer blades, and the actual swept height of the stirrer blades of the actual stirring system are calculated to complete the design of the actual stirring system.

[0013] Further, the specific formula for the shear stress equivalence relationship is:

[0014]

[0015] where N is the rotational speed of the actual stirrer, D Y is the actual diameter of the stirrer blades, D B is the actual inner diameter of the stirring tank, N 0 is the rotational speed of the stirrer, D Y0 is the diameter of the stirrer blades, D B0 is the inner diameter of the stirring tank.

[0016] Further, the shear stress τ of the shear stress equivalence relationship satisfies the following relationship:

[0017]

[0018] where η is the viscosity of the glass and C is the clearance between the stirrer blades and the inner wall of the stirring tank.

[0019] Further, the clearance C between the stirrer blades and the inner wall of the stirring tank satisfies the following relationship:

[0020]

[0021] Further, the specific formula for the stirring effect equivalence relationship is:

[0022]

[0023] or

[0024]

[0025] where T is the actual torque of the stirrer, P is the actual power of the stirrer, H is the actual swept height of the stirrer blades, Q is the actual extraction amount, T 0 is the torque of the stirrer, P 0 is the power of the stirrer, H 0 is the swept height of the stirrer blades, Q 0 is the extraction amount.

[0026] Further, the stirring effect E of the stirring effect equivalence relationship satisfies the following relationship:

[0027]

[0028] Further, the calculation formula for the actual swept height H of the stirrer blades is as follows:

[0029]

[0030] Further, the actual diameter D of the stirrer blades Y has the following calculation formula:

[0031]

[0032] Further, the actual inner diameter D of the mixing tank B has the following calculation formula:

[0033]

[0034] A design system for a stirring system in glass substrate manufacturing, which is used to implement the steps of the above-mentioned design method for a stirring system in glass substrate manufacturing, includes:

[0035] An acquisition module, which is used to select a standard stirring system as a reference stirring system, and respectively acquire parameters such as the swept height of the stirrer blades, the extraction amount, the inner diameter of the mixing tank, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer of the reference stirring system;

[0036] A shear stress module, which is used to establish an equivalent relationship of shear stress based on the inner diameter of the mixing tank, the diameter of the stirrer blades, and the rotation speed of the stirrer;

[0037] A stirring effect module, which is used to establish an equivalent relationship of stirring effect based on the swept height of the stirrer blades, the extraction amount, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer;

[0038] A design module, which is used to calculate the actual inner diameter of the mixing tank, the actual diameter of the stirrer blades, and the actual swept height of the stirrer blades of the actual stirring system according to the reference stirring system, the equivalent relationship of shear stress, and the equivalent relationship of stirring effect, and complete the design of the actual stirring system.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention provides a design method for a stirring system in glass substrate manufacturing. This method obtains parameters such as the swept height of the stirrer blades, the extraction volume, the inner diameter of the stirring tank, the diameter of the stirrer blades, the power of the stirrer, the rotational speed of the stirrer, and the torque of the stirrer of a reference stirring system, and respectively establishes an equivalent relationship of shear stress and an equivalent relationship of stirring effect. According to the corresponding relationships, the inner diameter of the actual stirring tank, the diameter of the actual stirrer blades, and the swept height of the actual stirrer blades of the actual stirring system are calculated, thereby completing the design of the actual stirring system. Based on the reference stirring system and the equivalence of shear stress and stirring effect, this method establishes design benchmarks for the swept height of the stirring blades, the diameter of the stirring blades, and the inner diameter of the stirring tank, and at the same time takes into account the creep of the stirring shaft and the optimization of system cost, and can meet the technical requirements of high-efficiency and high-homogenization stirring effect, so as to meet the needs of higher generations and higher extraction volumes.

[0041] The present invention also provides a design system for a stirring system in glass substrate manufacturing. Through this system, the steps of the above design method can be realized, meeting the needs of higher generations and higher extraction volumes. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic structural diagram of the geometric model of the stirring system provided by an embodiment of the present invention;

[0043] Figure 2 It is a schematic diagram of the cross-sectional design dimensions of the stirring system provided by an embodiment of the present invention;

[0044] Figure 3 It is a schematic diagram of the stirring simulation effect of the stirring system provided by an embodiment of the present invention;

[0045] Figure 4 It is a flowchart of a design method for a stirring system in glass substrate manufacturing provided by the present invention.

[0046] REFERENCE SIGNS:

[0047] 1 - Inlet end; 2 - Outlet end; 3 - Stirring tank; 4 - Stirring blades; 5 - Stirring shaft. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present invention provides a design method for a stirring system in glass substrate manufacturing, as Figure 4 shown, including the following steps:

[0049] Select a standard stirring system as the reference stirring system, and respectively obtain the parameters such as the swept height of the stirrer blades, the extraction volume, the inner diameter of the stirring tank, the diameter of the stirrer blades, the power of the stirrer, the rotational speed of the stirrer, and the torque of the stirrer of the reference stirring system;

[0050] Establish an equivalent relationship of shear stress according to the inner diameter of the stirring tank, the diameter of the stirrer blades, and the rotational speed of the stirrer;

[0051] Establish an equivalent relationship of stirring effect based on the swept height of the stirrer blade, the extraction volume, the diameter of the stirrer blade, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer;

[0052] According to the reference stirring system, the equivalent relationship of shear stress, and the equivalent relationship of stirring effect, calculate the inner diameter of the actual stirring tank, the diameter of the actual stirrer blade, and the swept height of the actual stirrer blade of the actual stirring system to complete the design of the actual stirring system.

[0053] Specifically, the specific formula for the equivalent relationship of shear stress is:

[0054]

[0055] where N is the rotation speed of the actual stirrer, D Y is the diameter of the actual stirrer blade, D B is the inner diameter of the actual stirring tank, N 0 is the rotation speed of the stirrer, D Y0 is the diameter of the stirrer blade, D B0 is the inner diameter of the stirring tank.

[0056] Especially, the shear stress τ of the equivalent relationship of shear stress satisfies the following relationship:

[0057]

[0058] where η is the viscosity of the glass and C is the clearance between the stirrer blade and the inner wall of the stirring tank.

[0059] And, the clearance C between the stirrer blade and the inner wall of the stirring tank satisfies the following relationship:

[0060]

[0061] Specifically, the specific formula for the equivalent relationship of stirring effect is:

[0062]

[0063] or

[0064]

[0065] where T is the torque of the actual stirrer, P is the power of the actual stirrer, H is the swept height of the actual stirrer blade, Q is the actual extraction volume, T 0 is the torque of the stirrer, P 0 is the power of the stirrer, H 0 is the swept height of the stirrer blade, Q 0 is the extraction volume.

[0066] Especially, the stirring effect E of the equivalent relationship of stirring effect satisfies the following relationship:

[0067]

[0068] The calculation formula for the actual swept height H of the agitator blade is as follows:

[0069]

[0070] The above-mentioned actual agitator blade diameter D Y The calculation formula is as follows:

[0071]

[0072] The above-mentioned actual inner diameter D of the mixing tank B The calculation formula is as follows:

[0073]

[0074] The present invention also provides a design system for a mixing system for manufacturing a glass substrate, including: an acquisition module, a determination module, a shear stress module, a mixing effect module, and a design module; the acquisition module is used to select a standard mixing system as a reference mixing system, and respectively acquire the swept height of the agitator blade, the extraction amount, the inner diameter of the mixing tank, the agitator blade diameter, the agitator power, the agitator speed, and the agitator torque of the reference mixing system; the shear stress module is used to establish an equivalent relationship of shear stress according to the inner diameter of the mixing tank, the agitator blade diameter, and the agitator speed; the mixing effect module is used to establish an equivalent relationship of mixing effect according to the swept height of the agitator blade, the extraction amount, the agitator blade diameter, the agitator power, the agitator speed, and the agitator torque; the design module is used to calculate the actual inner diameter of the mixing tank, the actual agitator blade diameter, and the actual swept height of the agitator blade of the actual mixing system according to the reference mixing system, the equivalent relationship of shear stress, and the equivalent relationship of mixing effect, and complete the design of the actual mixing system.

[0075] Embodiment

[0076] As Figure 1 shown, the mixing system includes an inlet end 1, an outlet end 2, a mixing tank 3, a mixing shaft 5, and a plurality of mixing blades 4; the mixing tank 3 is a cylindrical cavity, the inlet end 1 is arranged at the upper part of the side wall of the mixing tank 3; the outlet end 2 is arranged at the bottom of the mixing tank 3, the mixing shaft 5 is inserted and arranged at the top of the mixing tank 3, and the plurality of the mixing blades 4 are arranged in the mixing tank 3 along the shaft body of the mixing shaft 5.

[0077] In the manufacture of glass substrates, the stirring function in the platinum channel is to make the uneven molten glass more uniform and reduce the stripe defects in the finished glass substrates. Glass homogenization includes chemical uniformity and thermal uniformity. Different chemical phase stripes in the glass furnace are caused by refractory dissolution, melt stratification, glass surface volatilization, and temperature difference during the melting process. There are differences in color or refractive index. Platinum-rhodium defects smaller than 50 μm in glass manufacturing originate from the corrosion of the stirrer and the stirrer tank wall caused by the viscous shear stress of the stirrer. Among them, the homogenization mechanism: (1) By applying shear stress to the glass melt, stretching the non-uniform phase into thin stripes; (2) Cutting the stripes into short fragments through the plane of the stirrer blades perpendicular to the glass melt flow direction; (3) Making the glass generate radial flow to disperse the fragments through the blade shape that pushes the glass melt perpendicular to the overall flow direction.

[0078] According to Figure 2 shown, H is the sweep height (or sweep range) of the stirrer blades of the actual stirring system; D B is the inner diameter of the stirrer tank of the actual stirring system; D Y is the stirring diameter of the stirrer blades of the actual stirring system. Use the smallest stirring system to achieve the maximum degree of stirring to reduce the cost of precious metals such as platinum-rhodium. By coordinating the relationship between the stirrer speed, the shape of the stirrer / stirrer tank, and the glass viscosity, reduce the shear stress to a level lower than the level where unacceptable platinum-rhodium defects are formed, while maintaining the stirring efficiency and flow rate at a level that can only be achieved with high shear stress, so as to achieve the purpose of coordinating the contradiction between shear stress, flow rate, and stirring efficiency.

[0079] Among them, the calculation formula for the actual sweep height H of the stirrer blades is:

[0080]

[0081] The actual diameter D Y of the stirrer blades is calculated as:

[0082]

[0083] The actual inner diameter D B of the stirrer tank is calculated as:

[0084]

[0085] N is the rotational speed of the actual stirrer, D Y is the diameter of the actual stirrer blades, D B is the inner diameter of the actual stirrer tank, N 0 is the rotational speed of the stirrer, D Y0 is the diameter of the stirrer blades, D B0 is the inner diameter of the stirrer tank, H 0is the swept height of the stirrer blades of the reference stirring system; T is the actual stirrer torque, P is the actual stirrer power, H is the actual swept height of the stirrer blades, Q is the actual extraction rate, T 0 is the stirrer torque, P 0 is the stirrer power, H 0 is the swept height of the stirrer blades, Q 0 is the extraction rate.

[0086] As Figure 3 shown, a numerical analysis software for professional fluid mechanics (such as Ansys - Fluent) is applied to perform the coupled calculation of the thermal field and flow of the platinum channel stirring system. By studying the flow field and temperature field of the molten glass in the stirring tank, the flow pattern and homogenization effect law of the glass in the stirring tank are analyzed, and the optimal rotation speed of the stirrer is obtained.

[0087] Appropriate (not too large) shear stress results in a low platinum defect rate and high stirring (homogenization) efficiency. Stirring aims to achieve moderate homogenization at a given flow rate Q. The reduction of shear stress should not be achieved at the expense of stirring efficiency. Minimizing corrosion can extend the service life of the stirring system. For a given flow rate Q, to keep the stirring efficiency unchanged and reduce the shear stress, it is usually necessary to increase the stirrer diameter or the stirring volume, keeping H constant. In fact, this means increasing the residence time, so that even when the stirring speed is slow, sufficient homogenization of the glass melt can be maintained. The torque T should be kept low enough to prevent significant creep of the stirrer shaft due to torque stress at the stirring temperature.

[0088] The specific implementation process is as follows:

[0089] When the stirring system involved in this embodiment is working, the stirrer rotates uniformly at a set rotation speed under the drive of the transmission mechanism, so as to stir the molten glass entering the stirring tank 3 through the inlet end 1. The molten glass itself has thermal conductivity, and the temperature of the molten glass in the rear section of the stirring tank 3 may have reached the same temperature.

[0090] Reference stirring system: Inner diameter D of the stirring tank B0 = 360 mm, diameter D of the stirring blades Y0 = 300 mm, swept height H of the stirrer blades 0 = 610 mm, rotation speed N of the stirrer 0 = 8 rpm, extraction rate Q 0 = 22 T / Day.

[0091] Design the actual stirring system: Actual rotation speed N of the stirrer = 8 rpm, actual extraction rate Q = 28 T / Day.

[0092] Assume Adopting the same motor and rated power P as the reference stirring system, and the same rotational speed N as the reference stirring system, then: the inner diameter D of the stirring tank B = 460.1 mm, the maximum diameter D of the stirring blades Y = 383.41 mm, the sweeping height H of the stirring blades of the stirrer = 732 mm.

[0093] In order to verify the equivalence of the shear stress, through calculation:

[0094]

[0095] In order to verify the equivalence of the stirring effect, through calculation:

[0096]

[0097] Through the method of this embodiment, the designed actual stirring system has the same stirring effect as the reference stirring system, taking into account the creep of the stirring shaft and the optimization of the system cost, and meeting the technical requirements of high-efficiency and high-homogenization stirring effect for the needs of higher generations and higher extraction amounts.

[0098] The above-mentioned embodiments are only one of the implementation manners that can implement the technical solution of the present invention. The scope of protection required by the present invention is not only limited by this embodiment, but also includes any changes, substitutions and other implementation manners that are easily conceivable by those skilled in the art within the technical scope disclosed by the present invention.

Claims

1. A design method for a stirring system in glass substrate manufacturing, characterized in that, it includes the following steps: Select a standard stirring system as the reference stirring system, and respectively obtain the swept height of the stirrer blades, the extraction amount, the inner diameter of the stirring tank, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer of the reference stirring system; Establish a shear stress equivalence relationship based on the inner diameter of the stirring tank, the diameter of the stirrer blades, and the rotation speed of the stirrer; Establish a stirring effect equivalence relationship based on the swept height of the stirrer blades, the extraction amount, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer; Based on the reference stirring system, the shear stress equivalence relationship, and the stirring effect equivalence relationship, calculate the actual inner diameter of the stirring tank, the actual diameter of the stirrer blades, and the actual swept height of the stirrer blades of the actual stirring system to complete the design of the actual stirring system; The specific formula of the shear stress equivalence relationship is: Among them, N is the actual agitator rotation speed, D Y is the actual agitator blade diameter, D B is the actual inner diameter of the mixing tank, N 0 is the agitator rotation speed, D Y0 is the agitator blade diameter, D B0 is the inner diameter of the mixing tank; The shear stress τ of the shear stress equivalence relationship satisfies the following relationship: where η is the viscosity of the glass, and C is the clearance between the stirrer blades and the inner wall of the stirring tank; The clearance C between the stirrer blades and the inner wall of the stirring tank satisfies the following relationship: The specific formula of the stirring effect equivalence relationship is: or Among them, T is the actual agitator torque, P is the actual agitator power, H is the actual agitator blade sweep height, Q is the actual extraction volume, T 0 is the agitator torque, P 0 is the agitator power, H 0 is the agitator blade sweep height, Q 0 is the extraction volume; The stirring effect E of the stirring effect equivalence relationship satisfies the following relationship: The calculation formula of the actual swept height H of the stirrer blades is: The actual agitator blade diameter D Y is calculated by the following formula: The inner diameter D of the actual stirring tank B The calculation formula is as follows:

2. A design system for a stirring system in glass substrate manufacturing, which is used to implement the steps of the design method for a stirring system in glass substrate manufacturing described in claim 1, characterized in that, it includes: An acquisition module, which is used to select a standard stirring system as the reference stirring system, and respectively obtain the swept height of the stirrer blades, the extraction amount, the inner diameter of the stirring tank, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer of the reference stirring system; A shear stress module, which is used to establish a shear stress equivalence relationship based on the inner diameter of the stirring tank, the diameter of the stirrer blades, and the rotation speed of the stirrer; A stirring effect module, which is used to establish a stirring effect equivalence relationship based on the swept height of the stirrer blades, the extraction amount, the diameter of the stirrer blades, the power of the stirrer, the rotation speed of the stirrer, and the torque of the stirrer; A design module, which is used to calculate the actual inner diameter of the stirring tank, the actual diameter of the stirrer blades, and the actual swept height of the stirrer blades of 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.

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