CN113045184B - Method for precisely adjusting manufacturing thickness of glass substrate - Google Patents

The invention provides a method for accurately adjusting the thickness of a glass substrate, which comprises the steps of firstly setting the air flow to zero, measuring the initial thickness of a group of glass substrates, then setting a group of flow, measuring the thickness of a group of glass substrates, calculating to obtain a flow response mathematical model and a thickness response mathematical model, then obtaining the flow before the thickness correction flow is accurately adjusted, measuring the thickness of the glass substrates, and calculating to obtain the flow after the thickness correction is accurately adjusted; and then applying the flow to a glass substrate manufacturing production line, manufacturing at least one glass substrate, measuring to obtain the thickness of the glass substrate, terminating thickness correction flow fine adjustment when the thickness of the glass substrate meets the thickness standard requirement, and re-performing thickness correction flow fine adjustment calculation when the thickness distribution standard requirement is not met until the requirement is met.

Method for precisely adjusting manufacturing thickness of glass substrate

Technical Field

The invention relates to the field of glass substrate manufacturing, in particular to a method for finely adjusting the manufacturing thickness of a glass substrate.

Background

Glass substrates used in the field of manufacturing flat panel displays such as general TFT-LCDs (thin film transistor displays) and PDPs (plasma display panels) are manufactured by overflow down-draw, and in a molding process, molten glass melted by a glass melting furnace is supplied to a fusion overflow down-draw molding apparatus. Display manufacturing requires larger and larger glass substrates to increase production efficiency and reduce costs. The larger the glass substrate, the more difficult the production thereof, the more complicated the quality control of the glass substrate.

The ribbon passes over edge rolls (edge rollers) and one or more sets of draw (stub) rolls. Edge rolls are used to control the width of the ribbon and pull rolls are used to control the draw force and speed of the ribbon. The cooling air thickness control system is close to the root of the overflow groove. The flow rate (flow) of air in current cooling air thickness control systems is manually adjusted by an operator. The cooling (or hot) air pipe is isolated from the glass belt by a silicon carbide box body (wall) with high conductivity, low expansion rate and high emission coefficient. The silicon carbide wall is relatively close to the glass ribbon to absorb heat from the molten glass. The local heat dissipation affects the local heat loss and thus the local temperature of the molten glass and the resulting thickness distribution of the glass ribbon in the width direction.

Disclosure of Invention

The invention provides a method for precisely adjusting the manufacturing thickness of a glass substrate, aiming at the problems that the sensing non-quantization property, the precision uncertainty and the efficiency instability exist in the manual experience sensing operation in the prior art, the control factors of the manufacturing precision of large-capacity, wide-width and thin glass substrates are more complex, and the control is more difficult to control.

The invention is realized by the following technical scheme:

a method for manufacturing a glass substrate with fine adjustment of thickness comprises the following steps:

Furthermore, cooling air flow and hot air flow are respectively sprayed in the air pipes.

s1, when the glass substrate firstly passes through the silicon carbide box body, the air flow of air pipes of the silicon carbide box body is set to be zero, and the initial thickness distribution t of a group of glass substrates is obtained ₀ (j) (j =1,2,3 \ 8230n); wherein N isThe total number of pairs of the air pipes on one side;

s2, inputting a group of flow Q (i) (i =1,2,3 \ 8230n) on the air flow of an air pipe of the silicon carbide box body; when the glass substrate is introduced into the silicon carbide box body again, measuring the thickness distribution t (j) (j =1,2,3 \8230N; wherein N is the total logarithm of the single side of the air pipe;

s3, setting a calculation formula of thickness response functions of different flows:

f(Q)＝γ ₃ Q ³ +γ ₂ Q ² +γ ₁ Q，

Δt(j)＝t(j)-t ₀ (j)；

wherein, γ ₃ 、γ ₂ And gamma ₁ Coefficients corresponding to different flow times; q is the flow number; delta t (j) is the thickness difference of the cold end measured glass substrate; t (j) is a thickness function of the cold end measured glass substrate; t is t ₀ (j) Measuring an initial thickness function of the glass substrate for the cold end;

s4, calculating to obtain gamma according to the thickness response functions of different flow rates set in the step S3 ₃ 、γ ₂ 、γ ₁ 、β ₁ 、β ₂ 、W _G And W _L The calculation formula is as follows:

wherein: gamma ray ₃ 、γ ₂ And gamma ₁ Coefficients corresponding to different flow times; n is the total number of pairs of the air pipes on one side; q is the flow number; w is a group of _G And W _L The response width of the air duct; beta is a ₁ Is the negative fluctuation coefficient of the air pipe; beta is a ₂ Is the negative offset coefficient of the air pipe; delta t (j) is the thickness difference of the cold end measured glass substrate; t (j) is a thickness function of the cold end measured glass substrate; t is t ₀ (j) Measuring an initial thickness function of the glass substrate for the cold end; j is the number of thickness measurement points; and i is the number of the air pipes.

Furthermore, the flow distribution Q of the glass substrate in the air pipe of the silicon carbide box body before fine adjustment ₀ (i) (i =1,2,3 \8230N) and cold end thickness detection system for measuring thickness distribution t of glass substrate ₀ (j) (j =1,2,3 \8230n); N) the flow rate control of the cooling air for the silicon carbide case was corrected and calculated as follows:

wherein N is the total logarithm of the single side of the air pipe; t is t ₀ (j) Measuring an initial thickness function of the glass substrate for the cold end; w _G And W _L The response width of the air duct; beta is a ₁ Is the negative fluctuation coefficient of the air pipe; beta is a ₂ The negative offset coefficient of the air duct; delta is the target correction thickness; j is the number of thickness measurement points; and i is the number of the air pipes.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention provides a method for precisely adjusting the thickness of a glass substrate, which comprises the steps of firstly, setting all the air flow to zero, and measuring the thickness distribution t of a group of glass substrates ₀ (j) (j =1,2,3 \8230N), optionally setting a group of flow Q (i) (i =1,2,3 \8230N), measuring a group of glass substrate thickness distribution t (j) (j =1,2,3 \8230N), and obtaining a flow response mathematical model and a thickness response mathematical model by least square fitting to obtain a distribution coefficient gamma ₃ 、γ ₂ 、γ ₁ 、β ₁ 、β ₂ 、W _G 、W _L (ii) a Second, the flow distribution before the thickness correction flow fine adjustment is Q ₀ (i) (i =1,2,3 \8230N), the thickness distribution t of the glass substrate was measured ₀ (j) (j =1,2,3 \8230N), and the flow distribution Q after thickness correction and fine adjustment was obtained by least square fitting ₁ (i) (i =1,2,3 \ 8230n); then, the flow rate is distributed Q ₁ (i) (i =1,2,3 \8230N) applied to a glass substrate manufacturing line, at least one glass substrate is manufactured and its thickness distribution t is measured ₁ (j) (j =1,2,3 \8230N), if t ₁ (j) And (j =1,2,3.. N meets the thickness distribution specification requirement, the thickness correction flow rate fine adjustment is stopped, if the thickness distribution specification requirement is not met, a new round of thickness correction flow rate fine adjustment calculation is carried out until the requirement is met, the defects of sensing invariability, precision uncertainty and efficiency instability existing in manual experience sensing operation are overcome, the steps from skilled manual sensing operation to accurate digital analog control are realized, and the plate thickness automatic control is finally realized.

Drawings

FIG. 1 is a flow chart of a method for fine tuning the thickness of a glass substrate according to the present invention;

FIG. 2 is a schematic diagram of an intelligent control structure for fine adjustment of the thickness of a glass substrate according to the present invention;

FIG. 3 is a schematic diagram showing the relative change of local temperature of glass substrates with different cooling air flow rates according to the present invention;

FIG. 4 is a schematic view showing the relationship between the relative change in temperature of the glass substrate and the flow rate of cooling air in the present invention;

FIG. 5 is a schematic view showing the fitting of the temperature of the glass substrate to the relative change of the glass substrate by the cooling wind according to the present invention;

FIG. 6 is a schematic diagram showing the relative variation of the temperature and thickness of the glass substrate according to the present invention;

FIG. 7 is a schematic view illustrating calculation of the relationship between the thickness response amplitude and the flow rate of the glass substrate according to the present invention;

FIG. 8 is a schematic view of a calculation example of relative thickness variation of a glass substrate according to the present invention;

FIG. 9 is a schematic view of a non-flow thickness correction of a glass substrate according to the present invention;

FIG. 10 is a schematic view of the thickness correction flow rate of the glass substrate according to the present invention;

FIG. 11 is a schematic view of a measured thickness profile and a thickness profile resolved in accordance with the present invention;

in the figure: 1-a silicon carbide box body; 2-air pipe; 3-glass substrate.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The invention provides a method for finely adjusting the thickness of a glass substrate, which comprises the following steps as shown in figure 1:

As shown in fig. 3 and 4, the relative change (decrease) in the temperature of the glass substrate due to the cooling air and the position in the width direction of the glass substrate are approximately gaussian in distribution by the simulation results. Along with the increase of the flow of the cooling air, the relative change of the temperature at the center of the glass substrate is intensified, and the flow is larger and closer to a linear law through accurate fitting of a polynomial.

According to FIG. 5, the glass sheet temperature and thickness response functions of the cooling (hot) air ducts are Δ T _i (x) And Δ t _i (x) Based on the results of the simulation study, the calculation formula of the glass substrate temperature response function is as follows:

wherein i is the number of cooling (hot) air pipes (i =1,2,3 \ 8230n); x is a position coordinate of the glass plate in the width direction; x is the number of _i The position coordinate of the ith cooling (hot) air pipe is shown; w _G And W _L To cool the response width of the (hot) ductwork.

The cooling air reduces the central temperature of the glass substrate and increases the thickness of the glass substrate, and the calculation formula of the thickness response function of the glass substrate is as follows:

wherein x is a position coordinate of the glass plate in the width direction; x is the number of _i The position coordinate of the ith cooling (hot) air pipe is shown; w _G And W _L Is the response width of the cooling (hot) air duct; beta is a ₁ Negative fluctuation of the air pipe; beta is a ₂ Is the offset coefficient.

Referring to FIG. 6, the ability of the above function to accurately describe the glass sheet thickness response of the cooling (thermal) plenum is illustrated. In FIG. 6, the vertical axis represents thickness response in microns, and the horizontal axis represents distance in millimeters across the width of the glass substrate from the cooling (heating) air plenum. The cross data points are temperature response functions and the diamond data points are thickness response functions.

The flow distribution function Q (i) (i =1,2,3 \8230n) of the invention satisfies the maximum measuring range Q of the flowmeter _max The unit is L/Hr;

s3, setting a calculation formula of response functions of different flow thicknesses:

f(Q)＝γ ₃ Q ³ +γ ₂ Q ² +γ ₁ Q，

Δt(j)＝t(j)-t ₀ (j)；

wherein, γ ₃ 、γ ₂ And gamma ₁ Coefficients corresponding to different flow times; q is the flow number; delta t (j) is the thickness difference of the cold end measured glass substrate; t (j) is a thickness function of the cold end measured glass substrate; t is t ₀ (j) Measuring an initial thickness function of the glass substrate for the cold end;

s4, calculating to obtain gamma according to the thickness response functions of different flow rates set in the step S3 ₃ 、γ ₂ 、γ ₁ 、β ₁ 、β ₂ 、W _G And W _L The calculation formula is as follows:

wherein: gamma ray ₃ 、γ ₂ And gamma ₁ Coefficients corresponding to different flow times; n is the blast pipeThe total single-sided logarithm of (a); q is the flow number; w _G And W _L The response width of the air duct; beta is a ₁ Is the negative fluctuation coefficient of the air pipe; beta is a ₂ Is the negative offset coefficient of the air pipe; delta t (j) is the thickness difference of the cold end measured glass substrate; t (j) is a thickness function of the cold end measured glass substrate; t is t ₀ (j) Measuring an initial thickness function of the glass substrate for the cold end; j is the number of thickness measurement points; and i is the number of the air pipes.

As shown in FIG. 7 and FIG. 8, which are the relationship between the glass substrate thickness response amplitude and the flow rate and the relative change of the thickness, respectively, γ is obtained from the fitting results ₃ ＝1.617024E-07、γ ₂ ＝-1.241270E-04、γ ₁ ＝3.397899E-02、W _G ＝2.45127、W _L ＝3.07725、β ₁ ＝7.140716E-01、β ₂ ＝3.566278E-02。

wherein N is the total number of pairs of the air pipes on one side; t is t ₀ (j) Measuring an initial thickness function of the glass substrate for the cold end; w _G And W _L The response width of the air duct; beta is a ₁ Is the negative fluctuation coefficient of the air pipe; beta is a ₂ Is the negative offset coefficient of the air pipe; delta is the target correction thickness; j is the number of thickness measurement points; and i is the number of the air pipes.

According to FIG. 9, the diamond-shaped point curve is the initial thickness distribution measured when all cooling ducts have a flow of 0; the square point curve is the thickness distribution measured for the given flow distribution; the circular point curve is the analytic thickness distribution obtained after the flow fine adjustment and correction, and the analytic flow distribution corresponding to the circular point curve is shown in fig. 10.

Referring to fig. 11, a circular dotted curve gives typical curve data for the thickness variation of a glass substrate ribbon calculated based on the present invention; the square point curve is actually measured glass substrate thickness distribution data. The simulation results are very close to the measurement results.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the following descriptions are only illustrative and not restrictive, and that the scope of the present invention is not limited to the above embodiments: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope of the present disclosure; such modifications, changes or substitutions do not depart from the spirit and scope of the embodiments of the present invention, and they should be construed as being included therein. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.