JP5327533B2 - Glass ribbon edge position management apparatus and method - Google Patents

Description

  The present invention relates to an edge position management apparatus and method for detecting an edge position of a glass ribbon in a molten metal bath in a float glass manufacturing apparatus.

  A glass plate manufacturing apparatus according to a float glass manufacturing method includes a melting furnace, a forer hearth, a molten metal bath (float bath), a slow cooling furnace, and a cutting device. Molten glass melted in the melting furnace is supplied to the forehearth and flows into the float bath from the opening of the forehearth twill. The float bath is filled with molten tin, so that the molten glass that has flowed into the float bath is cast on the molten tin solution to an equilibrium thickness (about 7 mm) and flattened.

  A lift-out roller for pulling out the glass ribbon from the float bath and carrying it into the slow cooling furnace is provided at the rear stage of the float bath. By driving this lift-out roller, the molten glass cast on the tin bath of the float bath advances in the form of a ribbon having a constant width downstream of the float bath while being pulled in the direction of the slow cooling furnace.

  The glass (glass ribbon) formed in a ribbon shape is carried into a slow cooling furnace from a float bath, and gradually cooled to room temperature while being conveyed by a layer roller in the slow cooling furnace. Then, the glass ribbon that has passed through the slow cooling furnace is cut and folded into a glass plate of a predetermined size by a cutting device.

  By the way, when manufacturing a glass plate with the float glass manufacturing method, the thickness of the glass ribbon is determined by the amount of molten glass flowing into the float bath, the plate thickness, and the pulling speed. Moreover, the inflow amount of a molten glass can be estimated by detecting the edge position of the molten glass in a float bath. Further, the amount of molten glass flowing into the float bath is determined by the gate opening amount that is varied by moving the forehearth wheel up and down.

  That is, in the float glass manufacturing method, the edge position of the glass ribbon is detected in order to make the glass ribbon have a desired thickness, and the vertical movement position of the tool is controlled based on this edge position.

  The edge position detection method is performed by imaging the edge of the glass ribbon with a monitoring camera and subjecting the output signal to an image processing unit. Accurate detection of the edge position of the glass ribbon within the float bath is essential to keep the glass sheet at the desired thickness dimension.

  Patent Document 1 discloses an example of an algorithm in image processing. The output signal from the surveillance camera is differentiated and sliced, and the result is analyzed by a computer to obtain the edge position.

  Patent Document 2 discloses another example of image processing. The output signal from the surveillance camera is displayed on the cathode ray tube, and the edge position is obtained by detecting the difference in luminance between the glass ribbon and the other.

JP-A-53-12919 JP-A-2-248336

  In the conventional glass ribbon edge position management device, it is difficult to detect the initial fluctuation of the glass ribbon at an early stage. For example, depending on where the edge detection position is set on the upstream side or the downstream side, when the subtle fluctuation of the glass ribbon can be detected changes. In addition, the ease of detecting changes also depends on the position.

  When the detection of the fluctuation of the glass ribbon is delayed, the tool cannot be moved in real time with respect to the fluctuation of the edge position of the glass ribbon, so that there is a problem that a time lag occurs in the thickness control of the glass ribbon.

  In the above Patent Documents 1 and 2, the specific position of the edge portion to be inspected is not specified, and the above-described problem may occur.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide an edge position management device and method for a glass ribbon that can detect an initial fluctuation of an edge position early and accurately. .

  According to the present invention, the molten glass is flowed into the molten metal bath from the molten glass supply unit, and an image pickup means for picking up an image of the vicinity region including the edge of the glass ribbon cast on the molten metal bath, and the image pickup means An image processing means for creating an approximate curve of the edge from pixel data included in an inspection image, and a spatial position of the approximate curve and a preset reference curve for a base portion of the glass ribbon An edge position of the glass ribbon, comprising: a detecting means for detecting a deviation; a display means for displaying at least the approximate curve; and a control means for controlling a casting state of the glass ribbon based on the deviation. Provide a management device.

  Further, the present invention provides the glass ribbon edge position management device in which both the approximate curve and the reference curve are simultaneously displayed on the display means.

  Further, the present invention provides the above-described glass ribbon edge position management device in which the image processing means performs at least one noise removal from the pixel data.

  Further, the present invention provides the edge position management device for a glass ribbon, wherein one of the control means is a twist of a molten glass supply unit.

  Further, in the image processing means, two approximate curves corresponding to the right side and the left side of the glass ribbon are calculated, one of them is mirror-reversed, and the edge position of the glass ribbon is determined to determine the degree of overlap between both approximate curves. Provide a management device.

  Moreover, the edge position management apparatus of said glass ribbon whose width | variety of the glass ribbon in a formation process is 2000 mm or more is provided.

  Moreover, the edge position management apparatus of said glass ribbon whose composition of the said molten glass is an alkali free glass is provided.

In addition, an imaging process for imaging a nearby region including an edge of a glass ribbon cast from the molten glass supply unit into the molten metal bath and cast on the molten metal bath, and an inspection image captured in the imaging process An image processing step of creating an approximate curve of the edge from the pixel data included in the image, and detecting a deviation between a spatial position of the approximate curve and a preset spatial position of the reference curve with respect to a root portion of the glass ribbon A detection step, a display step for displaying at least the approximate curve, a control step for controlling a casting state of the glass ribbon based on the deviation,
An edge position management method for a glass ribbon is provided.

  The main feature of the present invention is that the glass ribbon is controlled by first obtaining an approximate curve of the edge of the molten glass flowing into the molten metal bath from the molten glass supply section and comparing the position with the ideal curve. It is in. According to the present invention, the initial fluctuation of the edge position in the glass ribbon can be confirmed early and accurately.

  Furthermore, it is particularly preferable to determine the supply amount of the molten glass based on the edge position of the root portion of the glass ribbon. By adopting this method, the twill can be moved in real time in response to subtle fluctuations in the edge position. This method has an advantage that the thickness of the glass ribbon can be accurately controlled in real time and with high accuracy while the formation state of the glass ribbon is constantly changing due to various parameters.

  Specifically, the vicinity area including the root portion of the edge of the molten glass is imaged by the imaging means, the image signal output from the imaging means is image-processed by the image processing means, and the edge portion of the glass ribbon is removed. To detect. Then, an approximate curve is created based on a plurality of pixel data, and the coordinate data corresponding to the root portion of the approximate curve is compared with the coordinate data of the reference curve set in advance and stored in the edge position management device. Then, the deviation between the two is calculated, and this deviation is displayed on the display means.

  Thereby, the operator can confirm the initial fluctuation of the edge position at an early stage based on the deviation displayed on the display means. And an operator can control the plate | board thickness of a glass ribbon in real time by moving a tween according to the fluctuation | variation of the edge position of a root part.

  Alternatively, the edge position of the glass ribbon can be controlled by fully automatic processing by linking all of the control means from the detection means to computer control.

  According to the present invention, it is preferable that the display means displays the approximate curve and the reference curve simultaneously. The reference curve is an ideal edge curve such that the glass ribbon has a desired thickness. As a result, the deviation of the edge of the glass ribbon can be visually confirmed on the monitor by the operator, and it can be immediately determined whether or not the steady production continues stably.

  Furthermore, according to the present invention, it is preferable that the control means digitally controls a molten glass supply amount by a molten glass supply unit based on the deviation. Thereby, the supply amount of molten glass can be managed with high accuracy, and parameters such as the thickness of the glass substrate to be produced can be dramatically stabilized.

  As described above, according to the edge position management apparatus for glass ribbon of the present invention, the root portion of the edge position in the glass ribbon of molten glass that has flowed into the molten metal bath from the molten glass supply unit is imaged by the imaging means, and the glass Since the approximate curve of the edge of the ribbon is calculated, the initial fluctuation of the edge position can be confirmed early and accurately.

The top view of the glass plate manufacturing apparatus to which the edge position management apparatus of the glass ribbon of embodiment was applied The block diagram which showed the structure of the edge position management apparatus shown in FIG. Explanatory drawing of the inspection area set by the image processor Explanatory diagram of edge information reduced by performing smoothing processing Explanatory drawing showing an example of image processing by the image processing unit Explanatory drawing which created the approximate curve by subdividing the inspection area shown in FIG. The flowchart which shows each step of the inspection method in this invention

  A preferred embodiment of a glass ribbon edge position management device according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view of a glass sheet manufacturing apparatus 12 to which the glass ribbon edge position management apparatus 10 of the embodiment is applied, and FIG. 2 is a block diagram showing the configuration of the edge position management apparatus 10.

  As shown in FIG. 2, the prepared glass raw material is melted in a melting furnace 14 to become a molten glass 16, and this molten glass 16 passes from the melting furnace 14 through a forehearth (molten glass supply unit) 18 to a float bath (melted). Metal bath) 20 and flows into molten metal 22 in 20. As the molten metal 22, tin is generally used. The molten glass 16 that has flowed onto the molten metal 22 becomes a glass ribbon 24 by being cast in the width direction on the upstream side of the float bath 20.

  Further, by pulling the glass ribbon 24 in the casting direction while suppressing the width reduction of the glass ribbon 24 by the plurality of assist rolls 26, 26... Of FIG. It is formed on a glass plate having a target thickness.

  In the present invention, examples of the glass composition that can be used include soda-lime-based glass materials for building materials and plasma displays, and alkali-free glass materials for low-temperature polysilicon TFTs. In general, the glass composition for TFT has a high melting temperature, and various quality and performance required in the market are severe. Therefore, temperature control of the glass from the melting furnace to the molding process is more important.

  In addition, with the increase in the size of the mother glass substrate in recent flat panel display (FPD) applications, the glass ribbon has become wider than before. In the 1990s, instead of CRT, glass substrates for FPD began to be mass-produced, and G3 (550 × 650), G4 (680 × 880), G5 (1000 × 120), G6 (1500 × 1800), G7 ( 1900 × 2200) and the size has been gradually increased. At present, production of larger sizes such as G8 (2200 × 2400) and G10 (2800 × 3000) has already been started.

  Moreover, as a plate | board thickness of the glass plate finally formed, as a general building material use, it is 2-19 mm, a use, such as a solar cell panel, 3.2 mm, a plasma display use, 1.8-2.8 mm, LCD use And the thing of 0.4-0.7mm is mass-produced.

  In addition, as a thin product for LCD application, a product (for example, 0.3 mm) thinner than 0.4 mm can be produced.

  In the float manufacturing method, the assist roll 26 installed in the melting bath presses the surfaces on both sides of the glass ribbon 24 and forms a pair in the width direction, as shown in the partial enlarged view of FIG. The 26 rotation shafts 28 and 28 are arranged so as to have a square shape.

  The glass ribbon 24 formed to a predetermined thickness in the float bath 20 is drawn out from the bath surface of the molten metal 22 by lift-out rolls 30, 30... Disposed at the downstream outlet of the float bath 20.

  Thereafter, the glass ribbon 24 is gradually cooled to a temperature close to room temperature at the outlet of the slow cooling furnace 32 by being conveyed by the layer rolls 34, 34. The slowly cooled glass ribbon 24 is cut and folded by a cutting device 36 installed on the downstream side of the slow cooling furnace 32 to produce a glass plate G of a predetermined size.

  Further, as shown in FIG. 2, a tween 40 is supported on the molten glass supply gate 38 of the forehearth 18 so as to be movable up and down, and the tween 40 is moved up and down by the power of the servo motor 42. Thereby, since the opening amount of the opening part of the gate 38 is varied, the inflow amount of the molten glass 16 to the float bath 20 is adjusted.

  The edge position management apparatus 10 according to the embodiment includes a pair of monitoring cameras (imaging means) 44 and 46, an image processing unit (image processing means) 48, monitors (display means) 50 and 52, and a control unit (control means) 54. Consists of Further, the edge position management device 10 includes a tweezer driving unit 56 controlled by the control unit 54. The tweezer driving unit 56 controls the servo motor 42 that moves the tween 40 up and down based on a control signal from the control unit 54.

  The surveillance cameras 44 and 46 are arranged on the outer side of the observation windows 58 and 60 formed on the upstream side wall surface 21 constituting the float bath 20 as shown in FIG. Placed in position. The surveillance camera 44 disposed on the right side when viewed from the upstream side in the traveling direction of the glass ribbon 24 includes an edge 62A of the root portion of the right edge 62 of the molten glass 16 flowing into the float bath 20 from the opening of the gate 38. The neighborhood area is imaged.

  Further, the monitoring camera 46 disposed on the left side when viewed from the upstream side in the traveling direction of the glass ribbon 24 includes an edge 64A of the root portion of the left edge 64 of the molten glass 16 flowing into the float bath 20 from the opening of the gate 38. The vicinity area is imaged.

  The monitoring camera 44 is connected to the image processing unit 48 via a cable 66 as shown in FIG. 2, and the monitoring camera 46 is connected to the image processing unit 48 via a cable 68. The image processing unit 48 performs image processing on the image signals output from the monitoring cameras 44 and 46 using an algorithm described later, and detects the edge position of the neighboring region.

  Further, the right monitor 50 and the left monitor 52 are connected to the image processing unit 48, respectively. The right monitor 50 displays an image of the vicinity area including the edge 62A of the root portion of the right edge 62, which is captured by the right monitor camera 44, and the left monitor 52 is displayed by the left monitor camera 46. The captured image of the vicinity region including the edge 64A of the root portion of the left edge 64 is displayed.

Further, by switching a switch (not shown) of the image processing unit 48, the monitor 50 shows the thin line of FIG. 2 calculated by the control unit 54 based on the pixel of the root portion 62A imaged by the monitoring camera 44. the approximate curve C _1, the reference curve R ₁ shown by a thick line in FIG. 2 are displayed superimposed. Similarly, the monitor 52, based on the pixel of the root portion 64A, which is captured by the monitoring camera 46, which is calculated by the control unit 54, an approximate curve C ₂ indicated by thin lines in FIG. 2, the reference indicated by a thick line in FIG. 2 curve R ₂ is displayed superimposed. The reference curves R ₁ and R _{2 referred} to here are curves of edges at which the glass ribbon 24 has a desired thickness.

The deviation of the right approximate curve C ₁ (C ₂ ) with respect to the right reference curve R ₁ (R ₂ ) is calculated by the control unit 54, and the tweezer drive unit 56 is controlled based on the calculated deviation to control the tween 40. The opening amount of the opening is controlled.

  That is, when the deviation is biased to the plus side, the inflow amount of the molten glass 16 is larger than the reference amount. In this case, the tween 40 is moved downward to reduce the inflow amount of the molten glass 16. Further, the control unit 54 controls the tweezer driving unit 56. Further, when the deviation is negative, the flow rate of the molten glass 16 is less than the ideal amount. In this case, the control unit 54 controls the tween drive unit 56 so as to move the tween 40 upward. To control.

That is, the control unit 54 creates the right approximate curve C ₁ and the left approximate curve C ₂ based on the plurality of pixel data indicating the edges detected by the image processing unit 48, and these right approximate curves C _1. The left approximate curve C ₂ is compared with the pre-stored right reference curve R ₁ and left reference curve R ₂ , that is, an ideal curve for forming the glass ribbon 24 at a target thickness. Then, based on the comparison result, the twill driving unit 56 is controlled to control the opening amount of the opening 38 of the twill 40 and the like.

  Next, an algorithm of the edge position management device 10 will be described. FIG. 7 shows a flowchart of each step of the inspection method according to the present invention.

  When the image signals are output from the monitoring cameras 44 and 46, the image processing unit 48 sets the inspection area A where the edge of the glass ribbon 24 (the edge of the vicinity area including the root portion) exists as shown in FIG.

  In this case, by setting the inspection area A to a curved shape close to a typical ribbon edge shape instead of a quadrangle, the image processing can be speeded up, and erroneous detection is reduced. FIG. 3 illustrates an example in which image processing is performed on the edge 64 imaged by the left monitoring camera 46, but the image processing unit 48 is similar for the edge 62 imaged by the right monitoring camera 44. Perform image processing.

  Thereafter, pixel data and the like are processed in the inspection area A. In order to remove noise from the input image, the image processing unit 48 normally performs smoothing processing by moving average in the X (lateral image) direction, that is, smoothing processing of the image, and smoothing processing in the Y (vertical image) direction. However, if the smoothing process is performed, the edge information with a low contrast is reduced as shown in FIG. 4, so the image is scanned in the Y direction and becomes “bright ⇒ dark” from the top to the bottom of the image. To extract the area. The luminance of the pixel is a digital value of 255, and is set to 0 otherwise.

  Remove noise from the image. That is, when the image is processed in the order of “expansion → shrinkage → shrinkage → isolation point removal → expansion” and the isolated point noise is removed, it can be seen that the noise is reduced from the entire image as shown in FIG. Furthermore, noise is removed again from the image.

The control unit 54 creates an approximate curve for the entire pixel of luminance 255 remaining after noise removal by the calculation formula of X = aY ² + bY + c, and is away from the curve of the first approximate curve thus obtained by a certain distance or more. Remove the spot as noise.

  Next, the control unit subdivides the detection area into a width W frame (for example, 400 × 400 pixels) B as shown in FIG. 6 while shifting W / 2 in the horizontal direction. Note that the upper and lower sides of the actual frame B are preferably curved so as to follow the detection area A.

Next, the control unit 54 creates a second approximate curve with a formula of X = aY ² + bY + c and displays it on the monitor 52 in each area of the subdivided frame B (reference symbol in the figure). C _2).

Further, the position of the edge 64A at the root portion of the edge 64 of the glass ribbon 24 is obtained from the second approximate curve (C ₁ , C ₂ ). When the edge 64A of the root portion belongs to the subdivision regions of the two frames B and B, the average of the Y values obtained from the respective approximate curve equations is set as the edge position of the glass ribbon.

Next, the control unit 54 compares the obtained position of the edge 64A of the root portion with the edge position of the corresponding reference curve (R ₁ , R ₂ ) to calculate the amount of variation, and corrects the amount of variation. In this way, the tweezers 56 are controlled so that the top and bottom positions of the tween are driven and adjusted by the servo motor 42 to adjust the opening amount of the gate 38.

  Thereby, according to the edge position management device of the glass ribbon of the present embodiment, the edge 64A of the base portion of the edge 64 is imaged, and the twill 40 is controlled based on the inspection image. The thickness control of the glass ribbon 24 with respect to the fluctuation can be executed in real time.

Further, since the position of the edge 64A of the root portion and the edge position of the reference curve (R ₁ , R ₂ ) corresponding to the position are displayed on the monitor, that is, the initial fluctuation of the edge position is displayed. In the case where the human operation is performed together, the operator can confirm the initial fluctuation of the glass ribbon at an early stage. Then, the operator can confirm the initial fluctuation, drive the servo motor 42 of the tool 40, and adjust the vertical position of the tool 40 by manually operating the tool driving unit 56.

  When an approximate curve is used as in the embodiment, there is an advantage that a line passing through a plurality of points is calculated, so that it is not easily affected by noise. There is also an advantage that detection can be performed with high resolution at the sub-pixel level (the Y coordinate of the edge can be obtained with 0.1 pixel or less). Note that the approximate curve need not be a quadratic curve. If the order becomes too high, the approximate curve may be distorted irregularly due to the influence of noise.

  Also, if the order is small, the desired edge shape is not reflected. Therefore, if the subdivision width for obtaining the approximate curve is too wide, the shape of the edge to be obtained is not reflected (except when the type of approximate curve matches the edge shape), and if it is too narrow, it is affected by noise. Since it is easy, it is set to an appropriate area that is not too wide and not too narrow.

  DESCRIPTION OF SYMBOLS 10 ... Edge position management apparatus, 12 ... Glass plate manufacturing apparatus, 14 ... Melting furnace, 16 ... Molten glass, 18 ... Fore hearth, 20 ... Float bath, 21 ... Upstream side wall surface, 22 ... Molten metal, 24 ... Glass ribbon, 26 Assist roll, 28 ... Rotating shaft, 30 ... Lift-out roll, 32 ... Slow cooling furnace, 34 ... Layer roll, 36 ... Cutting device, 38 ... Gate, 40 ... Twill, 42 ... Servo motor, 44 ... Monitoring camera, 46 ... Monitoring camera 48 ... Image processing unit 50 ... Monitor 52 ... Monitor 54 ... Control unit 56 ... Twill drive unit 58 ... Peeping window 60 ... Peeping window 62 ... Right edge 62A ... Right edge 64 ... Left edge, 64A ... Edge of left edge, 66 ... Cable, 68 ... Cable

Claims (8)

Imaging means for imaging the vicinity region including the edge of the glass ribbon cast from the molten glass supply unit into the molten metal bath and cast on the molten metal bath;
Image processing means for creating an approximate curve of the edge from pixel data included in an inspection image imaged by the imaging means;
Detecting means for detecting a deviation between a spatial position of the approximate curve and a spatial position of a preset reference curve for the root portion of the glass ribbon;
Display means for displaying at least the approximate curve;
Control means for controlling the casting state of the glass ribbon based on the deviation;
An edge position management device for a glass ribbon, comprising:   The glass ribbon edge position management device according to claim 1, wherein both the approximate curve and the reference curve are simultaneously displayed on the display unit.   The glass ribbon edge position management device according to claim 1 or 2, wherein the image processing means performs at least one noise removal from the pixel data.   The edge position management device for a glass ribbon according to claim 1, 2 or 3, wherein one of the control means is a twist of a molten glass supply unit.   5. The image processing means calculates two approximate curves corresponding to the right and left sides of the glass ribbon, and mirror-inverts one of them to determine the degree of overlap between both approximate curves. The edge position management apparatus of the glass ribbon of description.   The edge position management device for a glass ribbon according to any one of claims 1 to 5, wherein a width of the glass ribbon in the forming step is 2000 mm or more.   The edge position management device for a glass ribbon according to any one of claims 1 to 6, wherein the composition of the molten glass is an alkali-free glass. An imaging step of imaging a nearby region including an edge of a glass ribbon cast from the molten glass supply unit into the molten metal bath and cast on the molten metal bath;
An image processing step of creating an approximate curve of the edge from pixel data included in the inspection image imaged in the imaging step;
For the root part of the glass ribbon, a detection step of detecting a deviation between the spatial position of the approximate curve and the spatial position of a preset reference curve;
A display step of displaying at least the approximate curve;
A control step of controlling the casting state of the glass ribbon based on the deviation;
An edge position management method for a glass ribbon, comprising:

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