Control method of ultra-thin float electronic glass steel bending defect

Abstract

The application discloses a kind of ultra-thin float method electronic glass tempering warping defect control methods, when warping defect is tortoise-shaped warping and glass tin permeation quantity>2 μg / cm 2 When, according to the size of the high-temperature zone of tin bath protective gas pressure and the high and low of hydrogen proportion in protective gas, adjust the amount of protective gas, hydrogen flow or the exhaust emission of tin bath exhaust pipe;When warping defect is tortoise-shaped warping and glass tin permeation quantity≤2 μg / cm 2 When, reduce the amount of sulfur dioxide used under glass plate or pass into sulfur dioxide on glass plate;When warping defect is tortoise-shaped warping, glass tin permeation quantity≤2 μg / cm 2 And the thickness difference of sulfur film under glass plate and on glass plate is≤0.1mm, or warping defect is boat-shaped warping, then adjust annealing lehr temperature.The application is aimed at tin bath section and annealing section in float forming glass process, different process parameters are adjusted according to different process conditions, to achieve the purpose of controlling glass warping defect, and the application scenario is widened.

Description

Technical Field

[0001] This invention relates to the field of glass production technology, specifically to a method for controlling warping defects in ultra-thin float electronic glass. Background Technology

[0002] In the process of forming ultra-thin float electronic glass, factors such as tin infiltration in the tin bath and uneven control of annealing stress often cause warping defects in the produced glass sheets during tempering.

[0003] As glass becomes thinner, its strength decreases. To improve the strength of glass, it is necessary to chemically temper the float glass. At a certain temperature, smaller sodium ions in the glass surface are exchanged with larger potassium ions in the molten salt through ion exchange. Due to the volume change after the exchange, compressive stress is formed on the surface of the glass and tensile stress is formed inside, thereby improving the strength of the glass.

[0004] Ultra-thin electronic glass produced using the float glass process has a different ion concentration on the upper and lower surfaces during the tin bath forming process. This difference in ion exchange during ion tempering can easily lead to warping and deformation. Furthermore, ultra-thin electronic glass has high requirements for flatness, and this tempering warping phenomenon will seriously affect the quality of the glass product.

[0005] Chinese invention patent CN114988675A discloses a control device and method for controlling warping defects in flat glass. It includes a first infrared thermal imaging thermometer and a second infrared thermal imaging thermometer installed inside an annealing furnace. The two thermometers detect the temperature of the upper and lower surfaces of the glass plate and transmit the detected data to an intelligent control system for comparison and analysis. Once an anomaly is identified, the intelligent control system issues a command, and the upper and lower temperature regulators, driven by the first and third drive components respectively, rapidly move to the abnormal temperature point on the glass plate. Nitrogen gas at a suitable temperature and pressure is then used to compensate for the temperature difference between the upper and lower surfaces of the glass, thereby ensuring a uniform temperature that meets the annealing process temperature requirements. This patent achieves the goal of controlling glass warping defects by controlling the uniform temperature of the upper and lower glass surfaces. However, this method is only applicable to glass warping defects caused by annealing temperature, and its application is relatively limited. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for controlling warping defects in ultra-thin float electronic glass. The method adjusts different process parameters according to different process conditions in the tin bath section and annealing section of the float glass forming process to achieve the purpose of controlling glass warping defects and broaden the application scenarios.

[0007] like Figure 1As shown, glass tempering warping defects are generally classified into two types: tortoise-shaped warping (…). Figure 1 (upper middle) and boat-shaped warping ( Figure 1 (Lower middle), most are turtle-shaped warped (the upper surface is the solder bath atmosphere surface, and the lower surface is the contact surface with the molten solder).

[0008] The technical solution of this invention is as follows:

[0009] A method for controlling warpage defects in ultra-thin float electronic glass includes the following steps:

[0010] S1 When the warpage defect is turtle-shaped warpage and the glass tin diffusion content is >2μg / cm 2 This warping, caused by tin penetration onto the lower surface of the glass, is due to the oxidation of the molten tin. The more severe the oxidation, the more severe the tin penetration. The degree of oxidation can be judged by observing the amount of tin ash in the triangular area at the tin bath outlet. A higher degree of oxidation requires consideration of the tin bath's sealing and molten tin protection. Specific procedures are as follows:

[0011] S11 If the protective gas pressure in the high-temperature zone of the solder bath is ≤30Pa, the sealing of the solder bath should be checked first. If the sealing is good, it is because the pressure of the solder bath is too low, and the oxidizing gas from the outside and the cooling section of the furnace seeps into the solder bath, causing the molten solder to oxidize. In this case, the amount of protective gas needs to be increased.

[0012] S12 If the protective gas pressure in the high-temperature zone of the solder bath is >30Pa, and the bath pressure reaches a certain level, the amount of oxidizing gas that has penetrated into the solder bath will basically tend to a small and stable value. At this time, the influence of the bath pressure will be greatly reduced. The hydrogen in the protective gas plays a role in reducing the oxidizing gas that has penetrated into the solder bath. At this time, it should be checked whether the hydrogen content in the protective gas is ≤4.5%. If it is, the hydrogen cannot effectively reduce the oxidizing gas. At this time, the hydrogen flow rate needs to be increased.

[0013] S13 If the protective gas pressure in the high-temperature zone of the solder bath is >30Pa and the hydrogen content in the protective gas is >4.5%, then adjust the exhaust gas discharge of the solder bath vent pipe to 1 / 3-1 / 4 of the total protective gas volume. The main function of venting is to discharge the tin oxide gas in the solder bath, reduce the tin oxide in the solder bath, and reduce the circulation of tin oxide in the solder bath. Vent pipes are arranged in pairs on both sides of the solder bath, and several pairs are arranged from the front end to the rear end of the solder bath.

[0014] S2 When the warpage defect is turtle-shaped warpage and the glass tin content is ≤2μg / cm 2 At this time, the warping defect is caused by excessive sulfur dioxide under the glass plate used in the slag box. Sulfur dioxide will react with the active alkali metal ions (Na+) on the outer layer of the glass plate. + The reaction of sulfur dioxide under the glass plate will cause a difference in ion concentration between the upper and lower surfaces of the glass, leading to warping during chemical tempering. In this case, the following steps should be taken:

[0015] S21 If the difference in sulfur film thickness between the underside of the glass plate and the glass plate is greater than 0.1 mm, then reduce the amount of sulfur dioxide used under the glass plate.

[0016] The introduction of sulfur dioxide under the glass plate in step S22 is to solve other glass defects such as scratches. If the scratches on the glass plate increase after using the method in step S21, the amount of sulfur dioxide used under the glass plate is restored and sulfur dioxide is introduced into the glass plate.

[0017] S3 When the warpage defect is turtle-shaped warpage and the glass tin penetration is ≤2μg / cm 2 Furthermore, when the difference in sulfur film thickness between the glass plate and the glass plate is ≤0.1mm, or when the warping defect is boat-shaped warping, this type of warping is caused by insufficient glass annealing, resulting in significant residual permanent stress in the glass. During chemical tempering, the original equilibrium state of the glass is disrupted due to reheating and ion exchange, causing stress changes that lead to glass warping. Solving warping caused by annealing requires improving the annealing effect. Float glass produced is in large sheets, which are repeatedly cut into smaller pieces for tempering to meet transportation and usage requirements. Additionally, uneven annealing can occur during the production and annealing of large sheets. Each sheet is numbered during production and use to trace its origin and determine whether the warping occurs in the middle, secondary edge, or edge, allowing for corresponding adjustments. Figure 4 As shown. If warping occurs in the middle of the glass plate, the temperature in annealing furnace zone A is 580℃, the temperature in the front zone B1 is 540℃ (upper limit annealing temperature), the temperature in the middle zone B2 is 470℃, the temperature in the rear zone B3 is 400℃ (lower limit annealing temperature), and the temperature in zone C is 300℃. At this time, the following operations can be performed: a combination of one or more of the following: lowering the temperature in zone A, raising the temperature in the middle of zone B, and raising the temperature at the rear of zone B.

[0018] Preferably, in step S11, the increase in protective gas is equal to (maximum amount of tin penetration at the edge of the glass plate - 2) × 12 Pa.

[0019] Preferably, in step S12, the increase in hydrogen flow rate = (maximum tin diffusion at the edge of the glass plate - 2) × 5 Nm 3 / h.

[0020] Preferably, in step S13, a flow meter is installed on the vent pipe to accurately control the amount of waste gas emitted from the tin bath.

[0021] Preferably, in step S3, when adjusting the temperature of the annealing furnace, each adjustment should not exceed 5°C to avoid causing other defects.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention addresses the tin bath and annealing sections in the float glass manufacturing process by adjusting different process parameters according to different process conditions to control glass warping defects, thus broadening the application scenarios.

[0024] 2. The method of the present invention can effectively control the tempering warping defects of ultra-thin electronic glass and improve the yield rate. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 These are schematic diagrams of glass plates with tortoise-shaped and boat-shaped warping.

[0027] Figure 2 This is a schematic diagram of the structure of the venting tube in this invention.

[0028] Figure 3 This is a schematic diagram of adding a sulfur dioxide pipe to a glass plate in this invention.

[0029] Figure 4 This is a schematic diagram of annealing furnace zones A, B, and C in this invention.

[0030] In the diagram, 1 is the tin bath; 2 is the vent pipe; 3 is the slag box; 4 is the sulfur dioxide pipe; 501 is the annealing kiln A zone; 502 is the annealing kiln B zone; 503 is the annealing kiln C zone; and 6 is the flow meter. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] The method for controlling warpage defects in ultra-thin float electronic glass according to the present invention includes the following steps:

[0033] S1 When the warpage defect is turtle-shaped warpage and the glass tin diffusion content is >2μg / cm 2This warping, caused by tin penetration onto the lower surface of the glass, is due to the oxidation of the molten tin. The more severe the oxidation, the more severe the tin penetration. The degree of oxidation can be judged by observing the amount of tin ash in the triangular area at the outlet of tin bath 1. If the degree of oxidation is high, the sealing of tin bath 1 and the protection of the molten tin need to be considered. The specific operation is as follows:

[0034] S11 If the protective gas pressure in the high-temperature zone of tin bath 1 is ≤30Pa, the sealing condition of tin bath 1 should be checked first. If the sealing condition is good, it is because the pressure of tin bath 1 is too low, and the oxidizing gas from the outside and the cooling section of the furnace seeps into tin bath 1, causing the molten tin to oxidize. At this time, the amount of protective gas needs to be increased. The increase in protective gas = (maximum amount of tin seepage at the edge of the glass plate - 2) × 12Pa.

[0035] S12 If the protective gas pressure in the high-temperature zone of solder bath 1 is >30Pa, and the bath pressure reaches a certain level, the amount of oxidizing gas penetrating into solder bath 1 will basically tend to a small and stable value. At this time, the influence of the bath pressure will be greatly reduced. The hydrogen in the protective gas plays a role in reducing the oxidizing gas penetrating into solder bath 1. At this time, it should be checked whether the hydrogen content in the protective gas is ≤4.5%. If so, the hydrogen cannot effectively reduce the oxidizing gas. In this case, the hydrogen flow rate needs to be increased. The increase in hydrogen flow rate = (maximum amount of solder penetrating at the edge of the glass plate - 2) × 5Nm 3 / h;

[0036] S13 If the protective gas pressure in the high-temperature zone of solder bath 1 is >30Pa and the hydrogen content in the protective gas is >4.5%, then adjust the vent pipe 2 of solder bath 1 (e.g., Figure 2 The exhaust gas emission of the tin bath 1 (as shown) is 1 / 3 to 1 / 4 of the total protective gas emission. The exhaust gas emission of the vent pipe 2 of the tin bath 1 is precisely controlled by the flow meter 6 installed on the vent pipe 2. When adjusting, the vent should be opened gradually from the front end of the tin bath to the rear end. The opening degree of the paired vent pipes 2 on both sides of the tin bath 1 should be consistent.

[0037] S2 When the warpage defect is turtle-shaped warpage and the glass tin content is ≤2μg / cm 2 At this time, the warping defect is caused by excessive sulfur dioxide under the glass plate used in slag box 3. Sulfur dioxide will react with the active alkali metal ions (Na+) on the outer layer of the glass plate. + The reaction of sulfur dioxide under the glass plate will cause a difference in ion concentration between the upper and lower surfaces of the glass, leading to warping during chemical tempering. In this case, the following steps should be taken:

[0038] S21 If the difference in sulfur film thickness between the underside of the glass plate and the glass plate is greater than 0.1 mm, then reduce the amount of sulfur dioxide used under the glass plate.

[0039] The introduction of sulfur dioxide under the glass plate in step S22 is to address other glass defects such as scratches. If the number of scratches on the glass plate increases after using the method in step S21, the amount of sulfur dioxide used under the glass plate should be restored, and as follows: Figure 3 As shown, a sulfur dioxide pipe 4 is added to the glass plate to introduce sulfur dioxide into the upper surface of the glass plate;

[0040] S3 When the warpage defect is turtle-shaped warpage and the glass tin penetration is ≤2μg / cm 2 Furthermore, when the difference in sulfur film thickness between the glass plate and the glass plate is ≤0.1mm, or when the warping defect is boat-shaped warping, this type of warping is caused by insufficient glass annealing, resulting in significant residual permanent stress in the glass. During chemical tempering, the original equilibrium state of the glass is disrupted due to reheating and ion exchange, causing stress changes that lead to glass warping. Solving warping caused by annealing requires improving the annealing effect. Float glass produced is in large sheets, which are repeatedly cut into smaller pieces for tempering to meet transportation and usage requirements. Additionally, uneven annealing can occur during the production and annealing of large sheets. Each sheet is numbered during production and use to trace its origin and determine whether the warping occurs in the middle, secondary edge, or edge, allowing for corresponding adjustments. Figure 4 As shown. If warping occurs in the middle of the glass plate, the temperatures in annealing furnace A zone 501 are 580℃, the front zone B1 temperature is 540℃ (upper limit annealing temperature), the middle zone B2 temperature is 470℃, the rear zone B3 temperature is 400℃ (lower limit annealing temperature), and the zone C temperature is 300℃. At this time, the following operations can be performed: lowering the temperature of annealing furnace A zone 501, raising the temperature of the middle zone B zone 502, and raising the temperature of the rear zone B zone 502; a combination of one or more of these methods can be used. When adjusting the annealing furnace temperature, each adjustment should not exceed 5℃ to avoid causing other defects.

[0041] Example 1

[0042] A certain electronic float glass production line received feedback from a customer that the glass sheets exhibited tempering warping during tempering. Samples were taken from the left, middle, and right sides of the glass sheet. The 1.1mm thick glass sheet was cut into 12cm × 7cm samples and then chemically tempered. After tempering, all samples bent towards the tin side, with the center bulging towards the air side, exhibiting a tortoise-shaped warping. The warping amount and tin penetration data for each sample are shown in Table 1.

[0043] Table 1

[0044]

[0045] As shown in Table 1, the tin diffusion amount of the glass sample is >2 μg / cm³. 2 The warping defect was determined to be caused by tin infiltration. Inspection revealed a significant amount of tin ash (tin dioxide) in the triangular area at the outlet of tin bath 1, indicating substantial tin oxidation. The production parameters for tin bath 1 at the time of sampling were as follows: tin bath 1 pressure maintained between 35-38 Pa, and hydrogen consumption in the high-temperature zone was 10 Nm³.3 / h, nitrogen consumption 625Nm 3 / h, meaning the hydrogen content in the protective gas is approximately 1.57%, less than 4.5%. Therefore, according to the formula (maximum tin penetration at the glass plate edge - 2) × 5Nm 3 The increase in hydrogen flow rate can be calculated as (4.6782-2)×5Nm / h 3 / h=13.391Nm 3 / h, rounded up, gives an increase in hydrogen flow rate of 13 Nm. 3 / h. After adjusting the hydrogen flow rate, the glass warpage and tin penetration were observed, and the results are shown in Table 2:

[0046] Table 2

[0047]

[0048] As can be seen from the observation results in Table 2, increasing the hydrogen flow rate significantly reduced both the amount of tin infiltration and the amount of warpage in the glass; however, when the hydrogen flow rate increased by 13 Nm... 3 After / h, the tin penetration amount basically dropped to 2μg / cm 2 As the amount of hydrogen was further increased, the amount of tin infiltration continued to decrease, but the amount of warpage remained basically unchanged, indicating that other factors may be affecting the glass warpage.

[0049] The thickness of the sulfur film on the underside and top of the glass sample was measured, and the difference between the sulfur film thickness on the underside and the sulfur film thickness on the top of the glass sample was calculated.

[0050] =0.18mm, at this time the total operating pressure of sulfur dioxide in slag box 3 is 70pa, the usage is relatively large, it can be reduced to 40pa, and the warping is observed to disappear.

[0051] Example 2

[0052] A certain electronic float glass production line produced glass sheets with tortoise-shell warping defects during tempering. Testing revealed that the lower surface of the glass samples showed tin penetration of 3.1 μg / cm³. 2 The amount of tin penetration is approximately 2 μg / cm² greater than that of the standard sample. 2 This refers to tempered glass warping caused by solder penetration, requiring increased protection of the molten solder. During the production of this sample, the operating conditions of solder bath 1 were: bath pressure: 31 Pa, greater than 30 Pa; hydrogen content in the high-temperature protective gas: 4.73%, greater than 4.5%; the first pair of vent pipes 2 were open at 100%, the second pair at 80%, and the others were closed; the total exhaust volume was 302.4 m³. 3 / h; Total protective gas consumption 1864m³ 3 / h. The tank pressure and the proportion of hydrogen in the protective gas in the high-temperature zone were both higher than standard conditions, and the amount of vented exhaust gas was 16% of the total protective gas. Therefore, increasing the use of vented exhaust gas was adopted to solve the warping defect. The amount of glass warping and tin penetration were observed, and the observation results are shown in Table 3:

[0053] Table 3

[0054]

[0055] As shown in Table 3, increasing the amount of vented exhaust gas significantly reduced both the amount of tin infiltration and the amount of warpage in the glass. When the amount of vented exhaust gas accounted for 1 / 3 of the total protective gas volume, warpage disappeared, and the amount of tin infiltration reached a relatively low level, indicating that tin infiltration reached a level that could not cause warpage even when the exhaust gas volume was less than 1 / 3. Since the tin bath 1 is a complex float glass forming device, significant adjustments to the venting process could cause other problems. Therefore, flow meters 6 were installed on each vent pipe 2 to measure the real-time vented exhaust gas volume, ensuring precise control and minimizing other impacts on the glass.

[0056] Example 3

[0057] A float glass production line in China experienced boat-shaped warping of its raw glass sheets during the tempering process, which was presumably caused by poor annealing. Testing revealed that the tin penetration on the lower surface of the glass was 1.8 μg / cm². 2 The tin penetration amount is less than 2 μg / cm³ than that of the standard sample. 2 The total operating pressure of sulfur dioxide in the slag box 3 of this production line is 20 Pa. The thickness of the sulfur film was measured, and the difference between the thickness of the sulfur film on the lower and upper surfaces of the glass was 0.04 mm, which is less than 0.1 mm of the standard sample. This verifies that the warping of the tempered glass was not caused by tin penetration and sulfur dioxide.

[0058] Tracing the source through sample numbering, the boat-shaped warping was found on the left secondary side of the original glass plate. Sampling and verification showed no warping in other areas. The temperature of the left secondary side of the annealing furnace was adjusted; the temperature in the middle of the left secondary side (zone B, 502) was increased from 467℃ to 472℃. After sampling and testing, the tempering warping disappeared. Generally, the probability of tempering warping caused by poor annealing is relatively low, and it can usually be resolved with minor adjustments.

[0059] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for controlling warpage defects in ultra-thin float glass for electronic tempering, characterized in that, Includes the following steps: S1 When the warpage defect is turtle-shaped warpage and the glass tin diffusion content is >2μg / cm 2 At that time, perform the following operations: S11 If the protective gas pressure in the high-temperature zone of the tin bath (1) is ≤30Pa, then increase the amount of protective gas used; S12 If the protective gas pressure in the high-temperature zone of the tin bath (1) is >30Pa and the hydrogen content in the protective gas is ≤4.5%, then increase the hydrogen flow rate; S13 If the protective gas pressure in the high temperature zone of the tin bath (1) is >30Pa and the hydrogen content in the protective gas is >4.5%, then adjust the exhaust gas discharge of the vent pipe (2) of the tin bath (1) to 1 / 3-1 / 4 of the total protective gas volume. S2 When the warpage defect is turtle-shaped warpage and the glass tin content is ≤2μg / cm 2 At that time, perform the following operations: S21 If the difference in sulfur film thickness between the underside of the glass plate and the glass plate is greater than 0.1 mm, then reduce the amount of sulfur dioxide used under the glass plate. S22 If other defects in the glass plate increase after using the method in step S21, then restore the amount of sulfur dioxide used under the glass plate and introduce sulfur dioxide into the glass plate. S3 When the warpage defect is turtle-shaped warpage and the glass tin penetration is ≤2μg / cm 2 When the difference in the thickness of the sulfur film between the bottom of the glass plate and the glass plate is ≤0.1mm, or when the warping defect is boat-shaped warping, the following operations are performed: a combination of one or more of the following: lowering the temperature of annealing furnace A zone (501), raising the temperature of the middle part of annealing furnace B zone (502), and raising the temperature of the rear end of annealing furnace B zone (502).

2. The method for controlling warpage defects in ultra-thin float electronic glass as described in claim 1, characterized in that, In step S11, the increase in protective gas is equal to (maximum amount of tin penetration at the edge of the glass plate - 2) × 12 Pa.

3. The method for controlling warpage defects in ultra-thin float electronic glass as described in claim 1, characterized in that, In step S12, the increase in hydrogen flow rate = (maximum tin diffusion at the edge of the glass plate - 2) × 5 Nm 3 / h.

4. The method for controlling warpage defects in ultra-thin float electronic glass as described in claim 1, characterized in that, In step S13, a flow meter (6) is installed on the vent pipe (2).

5. The method for controlling warpage defects in ultra-thin float electronic glass as described in claim 1, characterized in that, In step S3, when adjusting the annealing furnace temperature, each adjustment should not exceed 5°C.

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