Apparatus for manufacturing glass plates and method for manufacturing glass plates

Abstract

This method reduces the influence of wrinkles that occur during the formation of scribe lines when measuring the movement speed of a glass ribbon, thereby enabling accurate measurement of the movement speed. [Solution] The glass plate manufacturing apparatus 1 comprises a molding apparatus 2 for forming a glass ribbon R, a conveying apparatus 3 for conveying the glass ribbon R downward, a speed measuring apparatus 4 for measuring the movement speed of the glass ribbon R being conveyed downward, and a cutting apparatus 5 for cutting out a single sheet of glass plate Gp from the glass ribbon R. The cutting apparatus 5 includes a scribe apparatus 15 that forms a scribe line S from one end R1 side to the other end R2 side in the width direction of the glass ribbon R. The speed measuring apparatus 4 measures the movement speed of the region on one end R1 side of the glass ribbon R that is closer to the center in the width direction.

Description

Technical Field

[0001] The present invention relates to a manufacturing technique for a glass plate having a configuration for measuring the moving speed of a glass ribbon.

Background Art

[0002] In the field of manufacturing glass plates, a method of forming a glass ribbon by the down-draw method and cutting out a sheet-like glass plate from the formed glass ribbon is known.

[0003] In this method, in order to reduce variations and distortions in the thickness of the glass ribbon, it is necessary to accurately measure the moving speed of the glass ribbon.

[0004] As a method for measuring the moving speed of a glass ribbon, for example, according to Patent Document 1, it is disclosed that the moving speed of the glass ribbon is calculated based on the rotational speed of a traction roller that pulls the glass ribbon downward.

[0005] In this case, it is common for a plurality of traction rollers to be provided at multiple locations to sandwich both end portions in the width direction orthogonal to the moving direction of the glass ribbon. In the same document, it is understood that the moving speed of the glass ribbon is calculated based on the rotational speed of a part (for example, one) of the traction rollers.

[0006] Also, in the same document, cutting out a sheet-like glass plate from the formed glass ribbon is also disclosed. When cutting out the glass plate, as can be understood from FIGS. 2 and 3 of the same document, a scribe line (ruled line (60)) is formed on the glass ribbon (26) using a scribe cutter (ruled wheel (56)). Then, as can be understood from FIGS. 6D and 6E of the same document, bending stress is applied to the location where the scribe line is formed to fold the glass ribbon.

[0007] In this case, the scribe line extends along the width direction of the glass ribbon. Therefore, when forming the scribe line, the scribe cutter travels along the width direction of the glass ribbon. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2013-043828 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, as the scribe cutter travels along the width direction of the glass ribbon, wrinkles may occur in the ribbon. Specifically, wrinkles can occur in the latter half of the process, from the start to the end of the scribe line formation by the scribe cutter. Therefore, wrinkles may occur in the region of the glass ribbon at the end of the scribe line.

[0010] In this case, if some of the traction rollers used to measure the movement speed of the glass ribbon in Patent Document 1 are positioned at the terminal end of the scribed line in the glass ribbon, it becomes difficult to accurately measure the movement speed of the glass ribbon due to the effects of the aforementioned wrinkles.

[0011] From the above perspective, the object of the present invention is to enable accurate measurement of the moving speed of a glass ribbon by making it less susceptible to the influence of wrinkles that occur when scribe lines are formed during measurement. [Means for solving the problem]

[0012] (1) The first aspect of the present invention, which was devised to solve the above problems, is a glass plate manufacturing apparatus comprising: a molded body for forming a glass ribbon from molten glass; a conveying device for conveying the glass ribbon downward; a speed measuring device for measuring the moving speed of the glass ribbon conveyed downward by the conveying device; and a cutting device for cutting a single sheet of glass plate from the glass ribbon, wherein the cutting device comprises: a scribe device for forming a scribe line extending along the width direction of the glass ribbon from one end to the other end in the width direction perpendicular to the conveying direction of the glass ribbon; and a folding device for breaking the glass ribbon at the position where the scribe line is formed to obtain a single sheet of glass plate, and the speed measuring device is characterized by measuring the moving speed of the region on one end side of the center in the width direction of the glass ribbon.

[0013] In this configuration, the scribed line is formed by the scribe device from one end of the glass ribbon in the width direction to the other end, so the other end of the glass ribbon becomes the end of the scribed line. In this case, wrinkles are likely to occur in the region of the glass ribbon at the end of the scribed line during its formation. Therefore, in this configuration, the speed measuring device measures the movement speed of the region of the glass ribbon excluding the region at the end of the scribed line, that is, the region on one end side of the center of the glass ribbon in the width direction. As a result, the speed measuring device can measure the movement speed of the glass ribbon in a region where wrinkles are less likely to occur, enabling accurate measurement of the movement speed.

[0014] (2) In the configuration of (1) above, the molding apparatus further comprises a molded body for forming a glass ribbon from molten glass, and edge rollers for gripping both ends of the glass ribbon in the width direction as it descends from the molded body and feeding it downward, and the speed measuring device may measure the moving speed of the region of the glass ribbon that is on the width side of the contact portion with the edge roller. In this case, the "contact portion" above strictly means the mark left by the contact portion (the same applies hereinafter).

[0015] In this configuration, irregularities are formed at the contact point between the glass ribbon and the edge roller. Therefore, when using a contact-type speed measuring device (such as the measuring roller described later), the movement speed of the glass ribbon cannot be accurately measured due to the influence of these irregularities. Furthermore, the contact point between the glass ribbon and the edge roller has significant residual stress, which may cause the contact point to break and break off as the glass ribbon is transported downwards. For this reason, even when using a non-contact type speed measuring device (such as the non-contact sensor described later), the movement speed of the glass ribbon cannot be accurately measured. With this configuration, however, whether using a contact-type or non-contact type speed measuring device, the movement speed is measured in the area excluding the contact point between the glass ribbon and the edge roller, thus enabling accurate measurement of the movement speed.

[0016] (3) In the configuration of (1) or (2) above, the glass ribbon may have ears at both ends in the width direction that are thicker than the central part in the width direction, and the speed measuring device may measure the moving speed of the region of the glass ribbon that is closer to the center in the width direction than the ears.

[0017] Here, the lugs at both ends in the width direction of the glass ribbon have the aforementioned irregularities formed on some parts. Therefore, when a contact-type speed measuring device is used, the movement speed of the glass ribbon cannot be accurately measured due to the influence of the irregularities. In addition, the lugs have a large amount of residual stress, so they may break and fall off while the glass ribbon is being transported downwards. Therefore, whether a contact-type or non-contact-type speed measuring device is used, the movement speed of the glass ribbon cannot be accurately measured. With this configuration, the movement speed is measured in the area excluding the lugs of the glass ribbon, so accurate measurement of the movement speed is possible regardless of whether a contact-type or non-contact-type speed measuring device is used.

[0018] (4) In any of the configurations described in (1) to (3) above, the speed measuring device may include a measuring roller that rotates in contact with the glass ribbon, and measure the moving speed of the glass ribbon based on the rotational speed of the measuring roller.

[0019] Here, since the glass ribbon is a transparent material that is continuously molded, it is difficult to measure its movement speed non-contact by optical means or other methods. With this configuration, the movement speed is measured by bringing the measuring roller into contact with the glass ribbon, making accurate measurement of the movement speed possible.

[0020] (5) In the configuration of (4) above, the measuring roller may be a free roller. In this case, a free roller means a roller to which no rotational driving force is applied (the same applies hereinafter).

[0021] By using a free roller for the measuring roller, slippage between the glass ribbon and the measuring roller is reduced, making it possible to accurately measure the moving speed of the glass ribbon.

[0022] (6) In the configuration of (4) or (5) above, the molded body may further include an annealing furnace for slowly cooling the glass ribbon below, the conveying device may include an annealing roller for conveying the glass ribbon in the annealing furnace, the annealing roller gripping the area of ​​the glass ribbon on the central side in the width direction from the contact portion with the edge roller, and the speed measuring device may measure the moving speed of the area of ​​the glass ribbon excluding the contact portion with the annealing roller.

[0023] In this configuration, at the contact point between the glass ribbon and the annealing roller, glass powder and other materials adhering to the annealing roller may be pressed against the glass ribbon. This can cause minute cracks to form in the glass ribbon, potentially reducing its strength at that point. Therefore, if the measuring roller were to contact this cracked area to measure the glass ribbon's movement speed, the ribbon might break. With this configuration, the measuring roller contacts the area of ​​the glass ribbon excluding the contact point with the annealing roller to measure the movement speed, thus enabling accurate measurement of the movement speed without damaging the glass ribbon.

[0024] (7) In the configuration of (6) above, the speed measuring device may measure the moving speed of the region on the central side in the width direction rather than the contact portion with the slow cooling roller in the glass ribbon.

[0025] Here, according to the configuration of (6) above, it is also possible to measure the moving speed by bringing the measuring roller into contact with the region between the contact portion with the slow cooling roller and the contact portion with the edge roller in the glass ribbon. However, in this intermediate region, the thickness of the glass ribbon may not be constant. Therefore, if the measuring roller is brought into contact with the region on the central side in the width direction rather than the contact portion with the slow cooling roller of the glass ribbon as in the configuration here, the moving speed can be measured more accurately.

[0026] (8) In any of the configurations of (4) to (7) above, it further includes a cooling chamber for cooling the glass ribbon below the slow cooling furnace, the conveying device includes a support roller for supporting the glass ribbon in the cooling chamber, the support roller sandwiches the region on the central side in the width direction rather than the contact portion with the edge roller in the glass ribbon, and the speed measuring device may measure the moving speed of the region excluding the contact portion with the support roller in the glass ribbon.

[0027] Here, in the contact portion of the glass ribbon with the support roller, a situation may occur where glass powder or the like attached to the support roller is pressed from the support roller onto the glass ribbon. Due to this, minute cracks may be formed in the glass ribbon, and thus the strength at the formation location may become low. Therefore, if the measuring roller is configured to contact the formation location to measure the moving speed of the glass ribbon, the glass ribbon may be damaged. According to the configuration here, since the measuring roller is brought into contact with the region excluding the contact portion of the glass ribbon with the support roller to measure the moving speed, it is possible to accurately measure the moving speed without damaging the glass ribbon.

[0028] (9) In the configuration of (8) above, the speed measuring device may measure the moving speed of the region on the central side in the width direction rather than the contact portion with the support roller in the glass ribbon.

[0029] In the configuration described in (8) above, it is also possible to measure the moving speed by bringing the measuring roller into contact with the region between the contact point with the support roller and the contact point with the edge roller of the glass ribbon. However, the thickness of the glass ribbon may not be constant in this region. Therefore, as in the configuration described here, if the measuring roller is brought into contact with the region on the widthward side of the glass ribbon that is closer to the center than the contact point with the support roller, the moving speed can be measured more accurately.

[0030] (10) In any of the configurations described in (1) to (9) above, the glass ribbon comprises an effective region located towards the center in the width direction and an ineffective region which is the entire region toward the ends in the width direction from the effective region, and the speed measuring device may measure the moving speed of the ineffective region.

[0031] In this way, when using a contact-type speed measuring device, the device will come into contact with the non-effective area of ​​the glass ribbon, but not with the effective area. Therefore, it is possible to prevent foreign matter from adhering to or scratching the effective area. This improves the quality of the finished glass plate. Here, the effective area is the area used as the finished glass plate, and the non-effective area is the area that is discarded as unwanted material.

[0032] (11) In any of the configurations described in (4) to (10) above, the speed measuring device may include an auxiliary roller positioned on either side of the glass ribbon, corresponding to the measuring roller.

[0033] In this configuration, the glass ribbon is sandwiched between the measuring roller and the auxiliary roller, making it less likely for the glass ribbon to slip between them, thus enabling more accurate measurement of the glass ribbon's movement speed.

[0034] (12) In the configuration of (11) above, the auxiliary roller may be a drive roller. In this case, a drive roller means a roller to which rotational driving force is applied (the same applies hereinafter).

[0035] If the auxiliary roller, which is the drive roller, is driven by a motor capable of variable speed control, such as a servo motor, the following effects can be obtained. Specifically, when starting up the manufacturing equipment or during maintenance, the auxiliary roller and the measuring roller are brought into direct contact without the glass ribbon in between, and the measuring roller is rotated by the auxiliary roller. Then, by checking whether the rotation speed of the measuring roller also increases by N times when the rotation speed of the auxiliary roller is increased by N times, it is possible to confirm whether or not there is an error in the measurement result of the measuring roller. Therefore, with this configuration, it is possible to check in advance whether or not the measuring roller is functioning accurately using a simple method.

[0036] (13) In the configuration of (12) above, the rotational speed of the auxiliary roller may be controlled to follow the moving speed of the glass ribbon measured by the measuring roller.

[0037] In this configuration, the rotation speed of the auxiliary roller could be made to follow the conveying speed of the glass ribbon by the conveying device. However, slippage is unavoidable between the rollers of the conveying device and the glass ribbon. Therefore, it is difficult to precisely match the moving speed of the glass ribbon with the rotation speed of the auxiliary roller. With this configuration, the rotation speed of the auxiliary roller is made to follow the moving speed measured by the measuring roller, allowing for a more precise match between the moving speed of the glass ribbon and the rotation speed of the auxiliary roller.

[0038] (14) In any of the configurations (11) to (13) above, the measuring roller may be positioned on one side of the glass ribbon, and the auxiliary roller may be positioned on the other side of the glass ribbon, with a pressing force acting from the auxiliary roller to the measuring roller via the glass ribbon.

[0039] In this way, the pressing force acting from the auxiliary roller on the measuring roller makes it less likely for slippage to occur between the measuring roller and one side of the glass ribbon.

[0040] (15) In the configuration of (14) above, the scribe device may include a scribe cutter that forms a scribe line on the other surface of the glass ribbon, and a support that contacts one surface of the glass ribbon and supports the glass ribbon when the scribe cutter forms the scribe line.

[0041] In this way, when forming scribe lines on the glass ribbon, the direction in which the scribe cutter presses against the support coincides with the direction in which the auxiliary roller presses against the measuring roller. As a result, the glass ribbon is less likely to vibrate during scribe line formation, and the measurement of the glass ribbon's movement speed by the measuring roller becomes even more accurate.

[0042] (16) In any of the configurations described in (1) to (15) above, a guide roller for gripping the glass ribbon may be provided in a region of the glass ribbon that is on the other end side of the center in the width direction and at a height position corresponding to the speed measuring device.

[0043] In this way, the guide rollers can suppress the vibration of the glass ribbon at the appropriate point (a height corresponding to the speed measuring device), enabling more accurate measurement of the moving speed.

[0044] (17) In any of the configurations described in (4) to (16) above, at least the outer circumference of the measuring roller may be made of heat-resistant rubber.

[0045] This method reduces slippage between the glass ribbon and the measuring roller, enabling accurate measurement of the glass ribbon's movement speed. Furthermore, it reduces the impact of the glass ribbon's temperature (high temperature), thus extending the lifespan of the measuring roller.

[0046] (18) In any of the configurations described in (1) to (17) above, the speed measuring device may measure the moving speed of the glass ribbon in an area below the conveying device and above the scribe device.

[0047] If the glass ribbon's movement speed is measured in the area above the conveying device, it may not be possible to accurately measure the movement speed if the glass ribbon is deflected between the molding device and the conveying device. Also, if the glass ribbon's movement speed is measured in the area below the scribe device, it may not be possible to accurately measure the movement speed if the measurement point overlaps with the scribe line, or in the case of a contact-type speed measuring device, the glass ribbon may be damaged starting from the scribe line. With this configuration, the movement speed is measured in the area between the conveying device and the scribe device, so the movement speed can be accurately measured without damaging the glass ribbon.

[0048] (19) In the configuration of (18) above, a restricting member for restricting the vibration of the glass ribbon may be provided in the region below the speed measuring device and above the scribe device.

[0049] In this way, the vibrations of the glass ribbon that occur when forming scribe lines on the glass ribbon or when breaking the glass plate from the glass ribbon are less likely to be transmitted to the position of the speed measuring device, thus enabling accurate measurement of the moving speed.

[0050] (20) In any of the configurations (1) to (3) above, the speed measuring device may measure the moving speed of the glass ribbon in a non-contact manner.

[0051] In this way, since the speed measuring device does not come into contact with the glass ribbon, the moving speed can be measured without damaging or breaking the glass ribbon, and without causing problems due to slippage with the glass ribbon.

[0052] (21) In the configuration of (20) above, the speed measuring device may include a plurality of sensors positioned below the position where the folding device folds the glass ribbon and capable of detecting the presence or absence of the glass ribbon, wherein the plurality of sensors are positioned at different positions in the vertical direction, and the speed of movement of the glass ribbon may be calculated using the time at which each of the plurality of sensors detects the position of the lower end surface of the glass ribbon formed by the folding device, and the vertical distance between each of the plurality of sensors.

[0053] Here, since the glass ribbon is a transparent material that is continuously molded, non-contact speed measurement using optical means is difficult. However, the position of the lower end surface (cut end surface) of the glass ribbon can be easily detected non-contact using a sensor capable of detecting the presence or absence of the glass ribbon. Therefore, by placing multiple sensors at different positions in the vertical direction, the movement speed of the glass ribbon can be accurately measured by a simple calculation using time and distance. Examples of sensors capable of detecting the presence or absence of a glass ribbon include laser sensors, ultrasonic sensors, or thermography.

[0054] (22) In any of the configurations described in (1) to (21) above, the cutting device may move downward in accordance with the moving speed of the glass ribbon measured by the speed measuring device.

[0055] In this configuration, the cutting device's movement speed could be made to follow the glass ribbon's transport speed by the conveying device. However, slippage is unavoidable between the rollers of the conveying device and the glass ribbon. Therefore, it is difficult to precisely match the glass ribbon's movement speed with the cutting device's movement speed. With this configuration, the cutting device's movement speed is made to follow the movement speed measured by the measuring roller, allowing for a more precise match between the glass ribbon's movement speed and the cutting device's movement speed.

[0056] (23) A second aspect of the present invention, devised to solve the above problems, is a method for manufacturing a glass plate, comprising: a molding step of forming a glass ribbon from molten glass; a transport step of transporting the glass ribbon downward; a speed measuring step of measuring the moving speed of the glass ribbon during the transport step; and a cutting step of cutting a single sheet of glass plate from the glass ribbon, wherein the cutting step comprises: a scribing step of forming a scribe line extending along the width direction of the glass ribbon from one end to the other end in the width direction perpendicular to the transport direction of the glass ribbon; and a folding step of folding the glass ribbon at the position where the scribe line is formed to obtain a single sheet of glass plate, and the speed measuring step is characterized by measuring the moving speed of the region on one end side of the center in the width direction of the glass ribbon.

[0057] According to this method of manufacturing glass plates, substantially the same effects and advantages as those in the configuration described in (1) above can be obtained. [Effects of the Invention]

[0058] According to the present invention, when measuring the movement speed of a glass ribbon, the influence of wrinkles that occur as a result of scribe line formation becomes less significant, enabling accurate measurement of the movement speed. [Brief explanation of the drawing]

[0059] [Figure 1] This is a perspective view showing the overall configuration of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 2] This is a longitudinal cross-sectional view taken along line AA in Figure 1. [Figure 3] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 4] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 5] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 6]This is a cross-sectional plan view illustrating the operation of the main part of a folding device, which is a component of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 7] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 8] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 9] This is a plan view showing the configuration of the main part of a speed measuring device, which is a component of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 10] This is a front view of the main components of a glass plate manufacturing apparatus according to the first embodiment of the present invention, viewed from one side (front side) of a glass ribbon. [Figure 11] This is a plan view showing a cross-section of a glass ribbon cut in the width direction. [Figure 12] This is a cross-sectional plan view illustrating the operation of a scribe device, which is a component of a glass plate manufacturing apparatus according to the first embodiment of the present invention. [Figure 13] This is a perspective view showing the overall configuration of a glass plate manufacturing apparatus according to a second embodiment of the present invention. [Figure 14] This is a longitudinal cross-sectional side view taken along the DD line in Figure 13. [Figure 15] This is a rear view of the main components of a glass plate manufacturing apparatus according to the second embodiment of the present invention, viewed from the other side (back side) of the glass ribbon. [Figure 16] This is a side view illustrating the operation of the main part of a glass plate manufacturing apparatus according to a second embodiment of the present invention. [Figure 17] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to a second embodiment of the present invention. [Figure 18] This is a longitudinal cross-sectional side view illustrating the operation of a glass plate manufacturing apparatus according to a second embodiment of the present invention. [Figure 19] This is a longitudinal cross-sectional side view showing the configuration of a glass plate manufacturing apparatus according to a modified example of the second embodiment of the present invention. [Figure 20]A perspective view showing a modified example of a scribe device, which is a component of the glass plate manufacturing apparatus according to the first and second embodiments of the present invention. [Modes for carrying out the invention]

[0060] Hereinafter, a glass plate manufacturing apparatus and a glass plate manufacturing method according to embodiments of the present invention will be described with reference to the attached drawings.

[0061] <First Embodiment> Figure 1 is a perspective view showing the overall configuration of a glass plate manufacturing apparatus 1 according to the first embodiment of the present invention, and Figure 2 is a longitudinal cross-sectional side view obtained by cutting along line AA in Figure 1. In the following description, the BB direction in Figure 1 will be described as the width direction, and the CC direction in Figure 1 will be described as the front-back direction (the same applies to the other figures).

[0062] As shown in Figures 1 and 2, the manufacturing apparatus 1 is broadly composed of a molding apparatus 2, a conveying apparatus 3, a speed measuring apparatus 4, and a cutting apparatus 5, arranged in order from top to bottom.

[0063] The molding apparatus 2 is located inside the molding furnace 6. The molding furnace 6 is a region for forming glass ribbons R from molten glass Gm by the overflow down-draw method. The molding apparatus 2 includes a molding body 7 that forms the glass ribbon R by converging the molten glass Gm overflowing from the upper end at the lower end. Furthermore, the molding apparatus 2 includes edge rollers 8 that clamp the edges R1 and R2 of the glass ribbon R formed by the molding body 7 from both sides in the front-back direction. These edge rollers 8 cool the glass ribbon R and suppress shrinkage of the glass ribbon R in the width direction.

[0064] Some components of the conveying device 3 are located inside the annealing furnace 9. The annealing furnace 9 is a region for reducing warping and distortion of the glass ribbon R, and the inside of the annealing furnace 9 has a predetermined temperature gradient downwards. Furthermore, annealing rollers 10, which are also components of the conveying device 3, are located inside the annealing furnace 9. The annealing rollers 10 are arranged in multiple vertical stages (two stages in the illustrated example) and clamp the ends R1 and R2 of the glass ribbon R in the width direction from both sides in the front-back direction.

[0065] The remaining components of the conveying device 3 are located in the cooling chamber 11. The cooling chamber 11 is a region for cooling the glass ribbon R to near room temperature. A gas at room temperature (e.g., 20°C ± 15°C) (e.g., clean air) is supplied to the cooling chamber 11, and no heating devices such as heaters are placed there. Furthermore, the support rollers 12, which are the remaining components of the conveying device 3, are located in the cooling chamber 11. The support rollers 12 are arranged in multiple vertical stages (two stages in the illustrated example) and clamp the glass ribbon R around both ends R1 and R2 in the width direction from both sides in the front-back direction.

[0066] In Figures 1 and 2, the configurations of the annealing furnace 9 and cooling chamber 11 have been simplified to facilitate understanding of the configurations of the speed measuring device 4 and the cutting device 5. Specifically, the vertical lengths of the annealing furnace 9 and cooling chamber 11 have been shortened, and the number of stages of the annealing rollers 10 and support rollers 12 has been reduced. Also, for convenience, in the following explanation, one end R1 in the width direction of the glass ribbon R shown in Figure 1 will be referred to as "end R1," and the other end R2 in the width direction will be referred to as "other end" (the same applies to other figures). Furthermore, one surface Ra of the glass ribbon R will be referred to as the front surface, and the other surface Rb will be referred to as the back surface (the same applies to other figures).

[0067] The speed measuring device 4 comprises a measuring roller 13 positioned on the surface Ra side of the glass ribbon R and an auxiliary roller 14 positioned on the back Rb side of the glass ribbon R. The measuring roller 13 and the auxiliary roller 14 are positioned opposite each other on both sides of the glass ribbon R in the front-back direction. The measuring roller 13 is in contact with the surface Ra of the glass ribbon R, and the auxiliary roller 14 is in contact with the back Rb of the glass ribbon R. The detailed configuration of the speed measuring device 4 and its surrounding components will be described later.

[0068] The cutting device 5 includes a scribe device 15 that forms scribe lines S extending in the width direction on the back surface Rb of the glass ribbon R, and a folding device 16 that folds the glass ribbon R at the positions where the scribe lines S are formed to obtain a single sheet of glass.

[0069] The scribe device 15 includes a scribe cutter 17 (shown as a solid line in Figure 2 for convenience) positioned on the back surface Rb side of the glass ribbon R, and a traveling mechanism 18 (shown as a dashed line in Figure 2 for convenience) also positioned on the back surface Rb side of the glass ribbon R and forcing the scribe cutter 17 to move in the width direction. In this embodiment, the scribe cutter 17 is composed of a disc-shaped member having blades on its peripheral edge. When forming a scribed line S on the glass ribbon R, the scribe cutter 17 moves from one end R1 side to the other end R2 side of the glass ribbon R by the operation of the traveling mechanism 18. The scribe cutter 17 is configured to move in the front-to-back direction and in the up-and-down direction in conjunction with the traveling mechanism 18.

[0070] Furthermore, the scribe device 15 includes a support 19 positioned on the surface Ra side of the glass ribbon R. The support 19 and the scribe cutter 17 are positioned opposite each other on both sides in the front-back direction of the glass ribbon R. The support 19 is composed of a member that is elongated in the width direction and has a support surface 19a that faces the surface Ra of the glass ribbon R. The support surface 19a is a plane that extends linearly in the width direction and is parallel to the vertical plane. The support 19 is configured to move in the front-back direction and in the vertical direction.

[0071] The folding device 16 consists of an upper folding device 20 positioned relatively above and a lower folding device 21 positioned relatively below.

[0072] The upper splitting device 20 includes a splitting body 22 positioned on the surface Ra side of the glass ribbon R. The splitting body 22 is composed of a member that is elongated in the width direction. Furthermore, the splitting body 22 has a contact end 22a that faces the surface Ra of the glass ribbon R. The contact end 22a is curved so as to be convex toward the tip side when viewed from the side.

[0073] Furthermore, the upper folding device 20 includes a dust collector 23 positioned on the back surface Rb side of the glass ribbon R. The dust collector 23 is elongated in the width direction. In addition, the dust collector 23 has a suction section (not shown) that sucks up glass powder generated when the glass ribbon R is folded. Both the folding body 22 and the dust collector 23 are configured to move in the front-to-back direction and in the up-and-down direction.

[0074] The lower folding device 21 includes a support mechanism 25 which serves as a support for the cutting target Rc, the part from which a single sheet of glass plate is cut from the glass ribbon R. The support mechanism 25 has a pair of arm members 24 positioned at one end R1 and the other end R2 in the width direction of the glass ribbon R. Both arm members 24 extend in the vertical direction. Furthermore, the support mechanism 25 has gripping members 27 attached to multiple locations (two locations in the illustrated example) in the vertical direction of each of the pair of arm members 24. Each gripping member 27 is open and closed, as shown by the solid line and the dashed line. The pair of arm members 24 are configured to rotate together in a vertical plane perpendicular to the width direction.

[0075] Here, we will explain the basic operation of this manufacturing apparatus 1, namely the operation of the scribe device 15 and the folding device 16.

[0076] First, as shown in Figure 3, when the glass ribbon R is moving downward, the arm member 24 of the folding device 16 (lower folding device 21) moves downward in accordance with the movement, and the gripping member 27 grips the portion Rc of the glass ribbon R that is to be cut. Even after gripping, the arm member 24 continues to move downward in accordance with the glass ribbon R. At this time, the scribe cutter 17 and support 19 of the scribe device 15, and the folded body 22 and dust collector 23 of the folding device 16 (upper folding device 20) are waiting in a retracted position.

[0077] Next, as shown in Figure 4, the scribe cutter 17 and support 19 move downward, following the glass ribbon R, from the retracted position to the contact position. With the support 19 in contact with the surface Ra of the glass ribbon R, the scribe cutter 17 travels from one end R1 to the other end R2 of the glass ribbon R. This forms a scribe line S extending along the width direction on the back surface Rb of the glass ribbon R. The scribe cutter 17 and support 19 move downward, following the glass ribbon R, until the formation of the scribe line S is complete. After the formation of the scribe line S is complete, the scribe cutter 17 and support 19 return to their original retracted position.

[0078] Subsequently, as shown in Figures 5 and 6, the folding body 22 and the dust collector 23 move downward, following the glass ribbon R, from the retracted position to the contact position. In this case, the contact end 22a of the folding body 22 is in contact with the surface Ra of the glass ribbon R, while the dust collector 23 is slightly separated from the back surface Rb of the glass ribbon R. At this point, as shown in Figure 6, in a plan view, the glass ribbon R extends in a straight line in the width direction, following the straight shape of the contact end 22a of the folding body 22.

[0079] Under these conditions, as shown in Figure 7, the pair of arm members 24 rotate together, causing their orientation to shift from a vertical to an inclined position. This applies bending stress to the formation of the scribe line S on the glass ribbon R, due to the longitudinal curvature. This bending stress causes the glass ribbon R to break along the scribe line S, and as shown in Figure 8, a glass plate Gp is ​​cut from the glass ribbon R. The glass powder generated during this breaking process is sucked into the dust collector 23.

[0080] Here, the thickness of the glass ribbon R is 10 μm to 1000 μm. The thinner the glass ribbon R, the more likely wrinkles are to form in the glass ribbon as the scribe cutter moves through it. Therefore, the effect of the present invention in reducing the influence of wrinkles and enabling accurate measurement of the glass ribbon's movement speed is significant. For this reason, the upper limit of the thickness of the glass ribbon R is preferably 700 μm or less, and more preferably 500 μm or less. The length in the width direction of the glass ribbon R is 500 mm to 3800 mm. Furthermore, the glass plate Gp cut from the glass ribbon R is used as a glass substrate or cover glass in panel displays such as liquid crystal displays and organic EL displays.

[0081] Next, we will describe the detailed configuration of the speed measuring device 4 and the surrounding configuration.

[0082] Figure 9 is a plan view showing the state in which the measuring roller 13 and auxiliary roller 14 of the speed measuring device 4 are holding the glass ribbon R. As shown in the figure, the measuring roller 13 is in contact with the surface Ra of the glass ribbon R. The auxiliary roller 14 is in contact with the back surface Rb of the glass ribbon R.

[0083] A first roller shaft 30 is integrally attached to the measuring roller 13, extending from one end R1 in the width direction of the glass ribbon R. The first roller shaft 30 is rotatably supported by a plurality of bearings 31 (two in the illustrated example). Therefore, the measuring roller 13 is rotatably cantilevered. The measuring roller 13 is held so as not to move in either the vertical or horizontal direction.

[0084] Furthermore, the measuring roller 13 is a free roller. The outer circumference or all of the measuring roller 13 is made of heat-resistant rubber. Examples of heat-resistant rubbers used include fluororubber, ethylene propylene rubber, and nitrile rubber.

[0085] The measuring roller 13 measures the moving speed of the glass ribbon R by rotating in contact with the surface Ra of the glass ribbon R. For this purpose, the speed measuring device 4 is equipped with a rotational speed detector 32 that detects the rotational speed of the measuring roller 13. In this embodiment, a rotary encoder is used as the rotational speed detector 32. Furthermore, the speed measuring device 4 is equipped with a calculation unit 33 that calculates the moving speed of the glass ribbon R based on the rotational speed of the measuring roller 13 detected by the rotational speed detector 32. In this calculation unit 33, the peripheral speed of the measuring roller 13 (the moving speed of the outer surface of the measuring roller 13) is calculated as the moving speed of the glass ribbon R.

[0086] A signal indicating the movement speed of the glass ribbon R measured by the measuring roller 13 (a signal indicating the measurement result of the measuring roller 13) is sent to the cutting device 5 (scribe device 15 and folding device 16). As a result, the scribe cutter 17, support 19, folding body 22, dust collector 23, and the pair of arm members 24 move downward in accordance with the movement speed of the glass ribbon R measured by the measuring roller 13.

[0087] A second roller shaft 34 is integrally attached to the auxiliary roller 14, extending from one end R1 of the glass ribbon R. The second roller shaft 34 is rotatably supported by multiple (two in the illustrated example) bearings 35. Therefore, the auxiliary roller 14 is rotatably cantilevered. The auxiliary roller 14 is held in place so as not to move in the vertical direction.

[0088] Furthermore, the auxiliary roller 14 is a drive roller that is rotationally driven by a motor M such as a servo motor. The rotational speed of the motor M is variably controlled by the controller 36.

[0089] Furthermore, the auxiliary roller 14 is pressed against the measuring roller 13 by a pressing means 37 such as an air cylinder. Therefore, a pressing force is applied from the auxiliary roller 14 to the measuring roller 13 via the glass ribbon R.

[0090] Furthermore, the rotational speed of the auxiliary roller 14 is controlled to follow the movement speed of the glass ribbon R, which is measured by the measuring roller 13. Here, the signal indicating the measurement result of the measuring roller 13 is input to the controller 36. Therefore, in this case, the control is performed by the controller 36 based on the signal indicating the measurement result of the measuring roller 13 (the signal sent from the calculation unit 33).

[0091] With the configuration of the speed measuring device 4 described above, the following effects can be obtained. Since the measuring roller 13 is a free roller that contacts the surface Ra of the glass ribbon R, slippage between it and the surface Ra of the glass ribbon R is less likely to occur compared to the case where it is a driven roller. Therefore, the moving speed of the glass ribbon R can be measured accurately. Furthermore, since a pressing force from the auxiliary roller 14 acts on the measuring roller 13, slippage between it and the surface Ra of the glass ribbon R is made even less likely to occur.

[0092] Furthermore, since at least the outer circumference of the measuring roller 13 is made of heat-resistant rubber, this also makes it less likely for slippage to occur between it and the surface Ra of the glass ribbon R. Moreover, because it is less affected by the temperature (high temperature) of the glass ribbon R, the lifespan of the measuring roller 13 is extended.

[0093] On the other hand, since the auxiliary roller 14 is a drive roller and its rotational speed is variably controlled, when starting up or performing maintenance on the manufacturing apparatus 1, the auxiliary roller 14 and the measuring roller 13 can be brought into direct contact and the auxiliary roller 14 can be rotated to check whether the measuring roller 13 is operating correctly. More specifically, by checking whether the rotational speed of the measuring roller 13 also increases by exactly N times when the rotational speed of the auxiliary roller 14 is increased by N times while the auxiliary roller 14 and the measuring roller 13 are in direct contact, it is possible to check in advance whether the measuring roller 13 is operating correctly.

[0094] Furthermore, since the rotational speed of the auxiliary roller 14 is controlled to follow the moving speed of the glass ribbon R measured by the measuring roller 13, the moving speed of the glass ribbon R and the rotational speed of the auxiliary roller 14 can be precisely matched. In more detail, if the rotational speeds of the annealing roller 10 and support roller 12 of the conveying device 3 were to follow the moving speed of the glass ribbon R measured by the measuring roller 13, slippage between those rollers 10 and 12 and the glass ribbon R would inevitably occur. Therefore, it would be difficult to precisely match the rotational speeds of those rollers 10 and 12 with the moving speed of the glass ribbon R. In contrast, as described above, if the rotational speed of the auxiliary roller 14 is to follow the moving speed of the glass ribbon R measured by the measuring roller 13, such problems will not occur.

[0095] Furthermore, since the measuring roller 13 and auxiliary roller 14 are positioned below the conveying device 3 and above the scribe device 15, there is no interference with measuring the movement speed of the glass ribbon R. In other words, if the measuring roller 13 and auxiliary roller 14 are positioned above the conveying device 3, the glass ribbon R may bend between the conveying device 3 and the molding device 2, making it impossible to accurately measure the movement speed of the glass ribbon R with the measuring roller 13. On the other hand, if the measuring roller 13 and auxiliary roller 14 are positioned below the scribe device 15, the scribe line S formed on the glass ribbon R may pass through the measurement point of the measuring roller 13 and auxiliary roller 14, making it impossible to accurately measure the movement speed of the glass ribbon R, or the glass ribbon R may be damaged starting from the scribe line S. In contrast, as described above, if the measuring roller 13 and auxiliary roller 14 are positioned below the conveying device 3 and above the scribe device 15, such problems do not occur.

[0096] The auxiliary roller 14 applies a pressing force to the measuring roller 13 from the back side Rb of the glass ribbon R. The scribe cutter 17 runs while applying a pressing force to the support 19 from the back side Rb of the glass ribbon R. Therefore, the direction in which the pressing force is applied by the auxiliary roller 14 and the scribe cutter 17 is the same. As a result, vibrations in the glass ribbon R are less likely to occur when the scribe cutter 17 is running.

[0097] Figure 10 is a front view of the main parts of the manufacturing apparatus 1, viewed from the surface Ra side of the glass ribbon R. As shown in the figure, the annealing roller 10 and support roller 12 of the conveying apparatus 3 are positioned closer to the center in the width direction than the edge roller 8. In this embodiment, the annealing roller 10 and the support roller 12 are positioned at the same location in the width direction.

[0098] Therefore, the contact marks 41 (hereinafter referred to as the first contact marks 41) of the glass ribbon R with the annealing roller 10 and the support roller 12 are located closer to the center in the width direction than the contact marks 42 (hereinafter referred to as the second contact marks 42) of the glass ribbon R with the edge roller 8. In the figure, the first contact marks 41 are shown as a striated region with a relatively large pitch of cross-hatching, and the second contact marks 42 are shown as a striated region with a relatively small pitch of cross-hatching. In this case, the first contact marks 41 and the second contact marks 42 are spaced apart in the width direction, and a striated gap region 43 (a region without cross-hatching 43) exists between the first contact marks 41 and the second contact marks 42.

[0099] Figure 11 is a plan view showing a cross-section of a glass ribbon R when it is cut along its width. As shown in the figure, a tab Rm is formed in the region on the R1 side of the glass ribbon R in the width direction, and this tab is thicker than the central part in the width direction. Furthermore, an uneven surface Rn is formed in the region on the R1 side of the tab Rm in the width direction. This region where the uneven surface Rn is formed is the second contact mark 42. The region on the Rm where the uneven surface Rn is not formed is located within the striated gap region 43. The above explanation also applies to the region on the R2 side of the other end of the glass ribbon R in the width direction. Therefore, the same reference numerals are used for the same constituent elements in the region on the R2 side of the glass ribbon R shown in the figure.

[0100] Here, as shown in Figure 10, the measuring roller 13 is positioned in a region on the side of one end R1 rather than the center Rz in the width direction of the glass ribbon R. This provides the following effect. Specifically, as shown in Figure 12, when the scribe cutter 17 is run from one end R1 to the other end R2 in the width direction of the glass ribbon R to form a scribe line S, wrinkles Rp may occur in the glass ribbon R. More specifically, wrinkles Rp occur in the latter half of the time from the start to the end of the formation of the scribe line S by the scribe cutter 17.

[0101] Therefore, wrinkles Rp occur in the region on the terminal S2 side of the scribe line S in the glass ribbon R shown in Figure 10. Consequently, if the measuring roller 13 is positioned in the region on the terminal S2 side of the scribe line S in the glass ribbon R, it becomes difficult to accurately measure the moving speed of the glass ribbon R due to the influence of wrinkles Rp.

[0102] Therefore, if the measuring roller 13 is positioned in the region on the starting end S1 side of the scribe line S in the glass ribbon R, that is, in the region on the end R1 side of the center Rz in the width direction of the glass ribbon R as described above, the moving speed of the glass ribbon R can be accurately measured without being affected by wrinkles Rp.

[0103] In the following explanation based on Figure 10, the first contact mark 41, the second contact mark 42, the ear portion Rm, and the gap region 43 refer to the respective elements 41, 42, Gm, and 43 located on the R1 side of one end in the width direction of the glass ribbon R.

[0104] The measuring roller 13 is positioned towards the center in the width direction relative to the first contact mark 41. Therefore, the measuring roller 13 is positioned towards the center in the width direction relative to the second contact mark 42, the ear portion Rm, and the gap region 43. The distance L1 from the center Rz of the glass ribbon R in the width direction to the measuring roller 13 is longer than the distance L2 from the second contact mark 42 to the measuring roller 13.

[0105] Even with this arrangement, the measuring roller 13 can accurately measure the movement speed of the glass ribbon R for the following reasons. Specifically, since irregularities Rn are formed on the second contact marks 42 on the glass ribbon R, if the measuring roller 13 is positioned to interfere with the second contact marks 42, the movement speed of the glass ribbon R cannot be accurately measured due to the influence of the irregularities Rn. In addition, since the area where the second contact marks 42 are formed has a large amount of residual stress, the area where the second contact marks 42 are formed may break while the glass ribbon R is being transported downwards. This breakage also prevents the measuring roller 13 from accurately measuring the movement speed of the glass ribbon R. The same problem occurs with the lugs Rm. Therefore, by positioning the measuring roller 13 so as not to interfere with the lugs Rm, including the second contact marks 42, as described above, the movement speed of the glass ribbon R can be accurately measured.

[0106] Furthermore, minute cracks may form in the first contact mark 41 when glass powder and other materials adhering to the annealing roller 10 and support roller 12 are pressed against it by the annealing roller 10 and support roller 12. As a result, the strength of the glass ribbon R decreases at the location where the cracks are formed. Consequently, if the cracks come into contact with the measuring roller 13, it can lead to damage to the glass ribbon R. Therefore, by positioning the measuring roller 13 so as not to interfere with the first contact mark 41 as described above, the movement speed of the glass ribbon R can be accurately measured.

[0107] As a further configuration, as shown in the figure, the glass ribbon R has an effective region Rs, which is the central area in the width direction, and an ineffective region Rt, which is the entire area of ​​both the one end R1 and the other end R2 of the effective region Rs in the width direction. The effective region Rs is the area used as the product glass plate. The ineffective region Rt is the area that will be cut and removed as unnecessary in a later process. The measuring roller 13 is positioned within the ineffective region Rt. This prevents foreign matter from adhering to or scratching the effective region Rs, leading to an improvement in the quality of the product glass plate.

[0108] Here, the measuring roller 13 may be positioned within the grooved gap region 43. Therefore, the measuring roller 13 may interfere with areas in the ear portion Rm where the irregularities Rn are not formed. However, areas in the ear portion Rm where the irregularities Rn are not formed may have residual stress and some variation in thickness. For this reason, it is preferable that the measuring roller 13 be positioned within the grooved gap region 43 so as not to interfere with the entire area of ​​the ear portion Rm.

[0109] Furthermore, unlike the illustrated example, if the widthwise position of the slow-cooling roller 10 differs from the widthwise position of the support roller 12, the widthwise length of the first contact marks 41 will increase, or the two first contact marks 41 will be spaced apart in the widthwise direction. Even in such cases, the measuring roller 13 will be positioned so as not to interfere with the first contact marks 41. Therefore, the measuring roller 13 may be positioned in the striated gap area between the two first contact marks 41.

[0110] In the illustrated example, the second contact mark 42 is located closer to the center in the width direction at the height where the measuring roller 13 is positioned than at a position near the bottom of the edge roller 8. In this case, the position of the second contact mark 42 in the width direction refers to its position in the width direction at the height where the measuring roller 13 is positioned. Therefore, "a position closer to the center in the width direction than the second contact mark 42" means "a position closer to the center in the width direction than the second contact mark 42 at the height where the measuring roller 13 is positioned."

[0111] The explanations based on Figure 10 above also apply to the auxiliary roller 14. While it is preferable that the widthwise length of the auxiliary roller 14 and the widthwise length of the measuring roller 13 are the same, the widthwise length of one may be longer than the widthwise length of the other.

[0112] The surrounding configuration of the speed measuring device 4 is as follows.

[0113] As shown in Figures 1 and 10, a guide roller 45 is positioned in the region of the glass ribbon R on the other end R2 side of the center Rz in the width direction, and at a height corresponding to the measuring roller 13. In the illustrated example, the guide roller 45 is provided at one location in the width direction and consists of a pair that clamps the glass ribbon R from both sides in the front-back direction. Both of the guide rollers 45 are free rollers. The first contact mark 41, second contact mark 42, ear portion Rm, and gap region 43 shown in Figure 10 are formed in a similar manner on the back surface Rb of the glass ribbon R.

[0114] Preferably, the positional relationship between the pair of guide rollers 45 and the first contact mark 41, second contact mark 42, ear portion Rm, and gap region 43 formed on the other end R2 side in the width direction of the glass ribbon R is the same as in the case of the measuring roller 13 described above, on the surface Ra and back surface Rb of the glass ribbon R. In this case, since the clamping force of the pair of guide rollers 45 is smaller than the pressing force acting from the auxiliary roller 14 on the measuring roller 13, the above positional relationship may be partially or completely different from that of the measuring roller 13 described above. However, it is preferable that the pair of guide rollers 45 are arranged without interfering with the second contact mark 42 or the ear portion Rm.

[0115] In the illustrated example, the pair of guide rollers 45 are positioned at the same height as the measuring roller 13, but their vertical positions may differ slightly from those of the measuring roller 13. However, even in this case, it is preferable that they be positioned at substantially the same height. In this case, the pair of guide rollers 45 are positioned above the scribe device 15 and below the conveying device 3 (the lowest support roller 12).

[0116] By providing a pair of guide rollers 45 in this manner, the shaking of the glass ribbon R can be suppressed at a height corresponding to the measuring roller 13, allowing for accurate measurement of the glass ribbon R's movement speed without being affected by shaking.

[0117] Furthermore, a regulating member 46 (regulating roller 46 in the illustrated example) is positioned below the measuring roller 13 and above the scribe device 15 to restrict the vibration of the glass ribbon R by sandwiching it from both sides in the front-back direction. The regulating roller 46 is positioned in a region on one end R1 side of the center Rz in the width direction of the glass ribbon R, and in a region on the other end R2 side of the center Rz in the width direction of the glass ribbon R. Therefore, the glass ribbon R is sandwiched by two pairs of regulating rollers 46. The vertical separation distance L3 between the two pairs of regulating rollers 46 and the measuring roller 13 is shorter than the vertical separation distance L4 between the two pairs of regulating rollers 46 and the scribe device 15 (see Figure 10). Also, the vertical separation distance L3 between the two pairs of regulating rollers 46 and the measuring roller 13 is shorter than the vertical separation distance L5 between the two pairs of regulating rollers 46 and the lowest support roller 12.

[0118] Preferably, the positional relationship between the two pairs of restricting rollers 46 and the first contact marks 41, the second contact marks 42, and the gap region 43 formed on one end R1 and the other end R2 of the glass ribbon R in the width direction is the same as in the case of the measuring roller 13 described above, on the surface Ra and back surface Rb of the glass ribbon R. In this case, since the clamping force of each of the two pairs of restricting rollers 46 is smaller than the pressing force acting from the auxiliary roller 14 on the measuring roller 13, the above positional relationship may be partially or completely different from that of the measuring roller 13 described above. However, it is preferable that the two pairs of restricting rollers 46 are arranged without interfering with the second contact marks 42 or the lugs Rm.

[0119] By providing the restricting roller 46 in this manner, the vibration of the glass ribbon R that occurs when forming the scribe line S on the glass ribbon R using the scribe device 15 can be prevented from being transmitted to the positions of the measuring roller 13 and the auxiliary roller 14, and the moving speed of the glass ribbon R can be accurately measured. It is preferable that the restricting roller 46 is a free roller. If the restricting roller 46 is a free roller, it does not change the moving speed of the glass ribbon R, making it easier to accurately measure the moving speed of the glass ribbon R with the measuring roller 13.

[0120] Next, a method for manufacturing a glass plate according to the first embodiment of the present invention will be described. This manufacturing method comprises a molding step, a conveying step, a speed measurement step, and a cutting step. Furthermore, the cutting step comprises a scribing step and a folding step.

[0121] The molding process is a process in which a glass ribbon R is formed from molten glass Gm by a molding apparatus 2 (in this embodiment, a molded body 7 and an edge roller 8).

[0122] The conveying process involves conveying the glass ribbon R downwards using the conveying device 3 (in this embodiment, the slow-cooling roller 10 and the support roller 12).

[0123] The speed measurement step is a step in which the movement speed of the glass ribbon R is measured by the speed measuring device 4 during the execution of the conveying step. In the speed measurement step, the movement speed of the region of the glass ribbon R on one end R1 side of the center Rz in the width direction is measured.

[0124] The cutting process involves cutting out sheet-shaped glass plates Gp from the glass ribbon R using a scribe device 15 and a folding device 16.

[0125] The scribing process is a process in which a scribe line S is formed by a scribe device 15 from one end R1 to the other end R2 in the width direction of the glass ribbon R.

[0126] The folding process involves using a folding device 16 to fold the glass ribbon R at the position where the scribe line S is formed, thereby obtaining a single sheet of glass Gp.

[0127] <Second Embodiment> Figure 13 is a schematic perspective view showing the overall configuration of the glass plate manufacturing apparatus 1 according to the second embodiment of the present invention, and Figure 14 is a longitudinal cross-sectional side view cut along the DD line in Figure 13. As shown in these figures, the difference between the manufacturing apparatus 1 according to this second embodiment and the manufacturing apparatus 1 according to the first embodiment described above is that the speed measuring device 4 measures the movement speed of the glass ribbon R in a non-contact manner. More specifically, the speed measuring device 4 in this second embodiment is equipped with a plurality of sensors 50 (two in the illustrated example) for measuring the movement speed of the glass ribbon R in a non-contact manner. These sensors 50 are installed in fixed positions. With this configuration, it is possible to accurately measure the movement speed of the glass ribbon R without damaging the glass ribbon R and without causing problems due to slippage that occur when a contact-type speed measuring device is used.

[0128] The other components, namely the molding device 2, the conveying device 3, and the cutting device 5 (scribe device 15 and folding device 16), are the same as those of the first embodiment described above. Therefore, components common to both embodiments are denoted by the same reference numerals in Figures 13 and 14, and their descriptions are omitted (the same applies to other figures shown later).

[0129] As shown in Figures 13 and 14, the two sensors 50 are positioned at different vertical positions in the region below the point where the folding device 16 folds the glass ribbon R (in the illustrated example, the region below the upper folding device 20). Specifically, the two sensors 50 are positioned such that their respective detection positions (measurement positions) Rw and Rx are in the region below the folding point of the glass ribbon R by the folding device 16. The two sensors 50 then detect the position of the lower end surface (cut surface) Rv of the glass ribbon R formed by the folding of the glass ribbon R by the folding device 16. In this embodiment, the two sensors 50 are not tilted in either the vertical or front-to-back direction and are pointed in the same direction, but one sensor 50 and the other sensor 50 may be pointed in different directions.

[0130] In the illustrated example, the two sensors 50 are positioned on the back surface Rb side of the glass ribbon R. The two sensors 50 are capable of detecting the presence or absence of the glass ribbon R. Specifically, the two sensors 50 can be reflective laser sensors, ultrasonic sensors, thermographic sensors, etc. However, in the case of the two sensors 50, transmissive laser sensors may also be used, but in this case, unlike the illustrated example, the components of each sensor 50 (light-emitting part and light-receiving part) must be positioned on both the front surface Ra side and the back surface Rb side of the glass ribbon R. When transmissive laser sensors are used, accurate measurements can be performed without being affected even if the glass ribbon R vibrates.

[0131] On the other hand, as shown in the figure example, if two sensors 50, consisting of a reflective laser sensor, an ultrasonic sensor, and a thermograph, are placed only on the back surface Rb side of the glass ribbon R, the manufacturing apparatus 1 can be made more compact. More specifically, when the glass ribbon R is broken, if the orientation of the part to be cut Rc of the glass ribbon R changes from a vertical orientation to an inclined orientation, the part to be cut Rc of the glass ribbon R moves away from the two sensors 50. Therefore, the two sensors 50 can be placed closer to the glass ribbon R in a vertical orientation, thus making the manufacturing apparatus 1 more compact. Although this advantage cannot be obtained, the two sensors 50 may also be placed only on the front surface Ra side of the glass ribbon R. The advantage of being able to perform accurate measurements without being affected by vibrations occurring in the glass ribbon R can also be obtained in the same way when using a thermograph, as described above.

[0132] Here, since the glass ribbon R is a transparent body that is continuously molded, it is difficult to measure the movement speed of the glass ribbon R non-contact by optical means or the like. In contrast, if the configuration is such that the position of the lower end surface Rv of the glass ribbon R is detected as described above, the position of the lower end surface Rv can be easily detected non-contact by the sensor 50 that detects the presence or absence of the glass ribbon R, and the movement speed can be accurately measured.

[0133] In the illustrated example, the presence of the regulating roller 46 provides the advantage of being able to regulate the vibrations occurring in the glass ribbon R above the scribe device 15. However, the regulating roller 46 does not need to be placed, although this advantage would be lost.

[0134] As shown in Figure 14, the speed measuring device 4 is equipped with a calculation unit 51. The calculation unit 51 calculates the moving speed of the glass ribbon R using the time at which each of the two sensors 50 detects the position of the lower end surface Rv of the glass ribbon R, and the distance Lx between the two sensors 50. In this case, the distance Lx between the two sensors 50 means the vertical separation distance between the respective sensing parts 50a of the two sensors 50. Furthermore, considering that the orientations of the two sensors 50 may differ as described above, the distance Lx between the two sensors 50 means the vertical separation distance between the respective detection positions (measurement positions) Rw and Rx on the glass ribbon R by the two sensors 50. The moving speed of the glass ribbon R calculated by the calculation unit 51 is the value obtained by dividing the distance Lx between the two sensors 50 by the difference in the time at which each of the two sensors 50 detected the position.

[0135] Figure 15 is a front view of the main part of the manufacturing apparatus 1, viewed from the back surface Rb side of the glass ribbon R. As shown in the figure, the first contact marks 41, second contact marks 42, and gap areas 43 formed on the back surface Rb of the glass ribbon R are identical in appearance to the first contact marks 41, second contact marks 42, and gap areas 43 formed on the surface Ra of the glass ribbon R (see Figure 10).

[0136] As shown in Figure 15, the two sensors 50 are positioned to measure the moving speed of the glass ribbon R in the region on the side of one end R1 (which is also the region on the side of the starting end S1 of the scribe line S) rather than the center Rz in the width direction of the glass ribbon R. Therefore, the two sensors 50 can accurately measure the moving speed of the glass ribbon R without being affected by wrinkles Rp that may occur in the region on the end S2 side of the scribe line S in the glass ribbon R when the scribe cutter 17 is run.

[0137] Furthermore, the two sensors 50 are positioned at the same location in the width direction. More specifically, the sensing parts 50a of each of the two sensors 50 are positioned at the same location in the width direction. More specifically, the two sensors 50 are positioned so that their respective detection positions (measurement positions) on the glass ribbon R are at the same location in the width direction. In this way, even if there are cracks or chips in the lower end surface Rv of the glass ribbon R, or if the lower end surface Rv is cut at an angle, that is, even if the lower end surface Rv of the glass ribbon R does not extend in a straight line along the horizontal direction, the movement speed of the glass ribbon R can be accurately measured.

[0138] Furthermore, the two sensors 50 are positioned to measure the movement speed of the region on the widthward side of the ear portion Rm in the glass ribbon R. However, because the ear portion Rm has a large residual stress, it may break and fall off during measurement (between the time the upper sensor 50 detects the position of the lower end surface Rv and the time the lower sensor 50 detects the position of the lower end surface Rv). Therefore, even if the movement speed of the ear portion Rm is measured, the movement speed of the glass ribbon R cannot be accurately measured. In contrast, as described above, if the movement speed of the region on the widthward side of the ear portion Rm is measured, such a problem does not occur.

[0139] Furthermore, the two sensors 50 are positioned to measure the movement speed of the region of the glass ribbon R between the starting end S1 and the ending end S2 of the scribe line S. Here, the region of the glass ribbon R on one end R1 side of the starting end S1 of the scribe line S (and similarly the region on the other end R2 side of the ending end S2 of the scribe line S) is not folded along the scribe line S, so the cut end surface (lower end surface) Rv of the glass ribbon R is prone to damage. Therefore, after the upper sensor 50 detects the cut end surface Rv, but before the lower sensor 50 detects the cut end surface Rv, new chips or defects may occur on the cut end surface Rv in the region of the scribe line S on one end R1 side of the starting end S1. As a result, the movement speed of the glass ribbon R cannot be accurately measured in the region of the scribe line S on one end R1 side of the starting end S1. In contrast, as mentioned above, if the cutting surface Rv is in the intermediate region between the starting point S1 and the ending point S2 of the scribe line S, the cutting surface Rv will be the end surface that has been folded along the scribe line S, and therefore such a problem will not occur.

[0140] Furthermore, the two sensors 50 are positioned to detect the position of the lower end surface Rv of the glass ribbon R before the support mechanism 25 of the folding device 16 changes the orientation of the portion Rc to be cut from a vertical position to an inclined position. Here, as shown in Figure 16, after the support mechanism 25 changes the orientation of the portion Rc to be cut from a vertical position to an inclined position, the position of the lower end surface Rv of the portion Rc moves relatively upward by δ1 compared to when the portion Rc moves downward while remaining in a vertical position (shown by a dashed line in the same figure) (shown by a solid line in the same figure). Therefore, if the lower sensor 50 is positioned to detect the position of the lower end surface Rv of the portion Rc after the above orientation change, the time at which the lower sensor 50 detects the lower end surface Rv of the portion Rc will be delayed by the amount corresponding to δ1. The same applies if the upper sensor 50 is positioned to detect the position of the lower end surface Rv of the portion Rc after the above orientation change. Therefore, the movement speed of the glass ribbon R cannot be accurately measured. However, if the two sensors 50 are arranged to detect the position of the lower end surface Rv of the part to be cut Rc before the above-mentioned change in posture, such a problem will not occur.

[0141] In addition, a signal indicating the movement speed of the glass ribbon R, calculated by the speed measuring device 4 (calculation unit 51), is sent to the cutting device 5 (scribe device 15 and folding device 16). As a result, the scribe cutter 17, support 19, folding body 22, dust collector 23, and the pair of arm members 24 move downward in accordance with the movement speed of the glass ribbon R calculated by the calculation unit 51. Here, it is conceivable that the downward movement speed of the cutting device 5 should follow the conveying speed of the glass ribbon R by the conveying device 3, but slippage can inevitably occur between the rollers 10 and 12 of the conveying device 3 and the glass ribbon R. Therefore, it is difficult to accurately match the movement speed of the glass ribbon R with the movement speed of the cutting device 5. On the other hand, as described above, if the movement speeds of the components 17, 19, 22, 23, and 24 of the cutting device 5 are made to follow the movement speed of the glass ribbon R calculated by the calculation unit 51, such problems will not occur.

[0142] In the above configuration, it is preferable that the speed measuring device 4 measures the movement speed of the glass ribbon R when the gripping member 27 of the support mechanism 25 in the folding device 16 is moving downward while gripping the portion Rc of the glass ribbon R to be cut, as shown in Figure 17. That is, as shown in Figure 18, if the glass ribbon R has a warp that curves in the vertical direction, the lower end surface Rv of the glass ribbon R may swing up and down due to the effect of the warp between the time the glass ribbon R is folded by the folding device 16 and the time the glass ribbon R is gripped by the gripping member 27. Therefore, it is preferable that the speed measuring device 4 measures the movement speed of the glass ribbon R when the gripping member 27 is gripping the glass ribbon R and moving downward, and does not measure the movement speed of the glass ribbon R at any other time. During periods when the movement speed of the glass ribbon R is not measured, the movement speeds of components 17, 19, 22, 23, and 24 of the cutting device 5 should be adjusted to match the most recently measured movement speed of the glass ribbon R by the speed measuring device 4. If no problems arise due to the warping of the glass ribbon R, the speed measuring device 4 may always measure the movement speed of the glass ribbon R.

[0143] Furthermore, as a modification of this embodiment, the two sensors 50 of the speed measuring device 4 may measure the moving speed of the glass ribbon R by detecting the scribe lines S formed on the glass ribbon R. In this case, the arrangement of the two sensors 50 in the width direction is such that they measure the moving speed in the region between the start end S1 and the end end S2 of the scribe line S shown in Figure 15. In contrast, the arrangement of the two sensors 50 in the vertical direction is as shown in Figure 19. That is, the two sensors 50 are arranged below the scribe device 15 and above the folding device 16. Specifically, the two sensors 50 are arranged such that their respective detection positions (measurement positions) Rw and Rx exist in the region below the position where the scribe lines S are formed by the scribe device 15 on the glass ribbon R and above the folding position of the glass ribbon R by the folding device 16.

[0144] The calculation unit 51 of the speed measuring device 4 then calculates the moving speed of the glass ribbon R using the time at which each of the two sensors 50 detects the position of the scribe line S formed on the glass ribbon R, and the distance between the two sensors 50. In this case, the moving speed of the glass ribbon R calculated by the calculation unit 51 is the value obtained by dividing the distance between the two sensors 50 by the difference in the time at which each of the two sensors 50 detected the scribe line S. In this modified example, thermographic cameras or cameras (for example, industrial cameras for inspection) can be used as the two sensors 50.

[0145] Next, a method for manufacturing a glass plate according to the second embodiment will be described. This manufacturing method comprises a molding step, a conveying step, a cutting step, and a speed measurement step.

[0146] The molding process, conveying process, and cutting process are the same as those described in the manufacturing method according to the first embodiment.

[0147] The speed measurement process is a non-contact process for measuring the movement speed of the glass ribbon. A non-contact sensor is used in this speed measurement process.

[0148] Although embodiments of the present invention have been described above, the embodiments of the present invention are not limited thereto, and various modifications can be made without departing from the spirit of the invention.

[0149] For example, the scribe device 15 in the above embodiment may be replaced with a scribe device 15 as shown in Figure 20. More specifically, the scribe device 15 shown in Figure 20 has a support body 19 that supports a scribe cutter 17, which is positioned on the back surface Rb side of the glass ribbon R, from the surface Ra side of the glass ribbon R. This support body 19 is composed of a roller-shaped first support rotating body. This first support rotating body 19 moves together with the scribe cutter 17 in the direction of arrow E (the direction from one end R1 side to the other end R2 side in the width direction of the glass ribbon R). Furthermore, this scribe device 15 is equipped with a coating roller 52 that moves ahead of the scribe cutter 17 and at the same speed in the direction of arrow E on the back surface Rb side of the glass ribbon R. The coating roller 52 applies a liquid such as ethanol or methanol to the back surface Rb of the glass ribbon R. In addition, this scribe device 15 is equipped with a second support rotating body 53 that supports the coating roller 52 from the surface Ra side of the glass ribbon R. This second support rotating body 53 moves together with the coating roller 52 in the direction of arrow E. When a scribe line S is formed on a glass ribbon R using a scribe device 15 with such a configuration, wrinkles Rp may occur in the region of the glass ribbon R on the terminal S2 side of the scribe line S, as in the case described above.

[0150] In the above embodiment, the present invention was applied to an apparatus and method for manufacturing glass plates using the overflow downdraw method, but the present invention may also be applied to an apparatus and method for manufacturing glass plates using other methods, such as the slot downdraw method.

[0151] In the above embodiment, when the glass ribbon R is broken by the breaking device 16, the broken body 22 is in contact with the glass ribbon R while bending stress is applied to the glass ribbon R. However, the broken body 22 may be brought into contact with the glass ribbon R while bending stress is applied to the glass ribbon R.

[0152] In the above embodiment, when the glass ribbon R is broken by the breaking device 16, the broken body 22 is brought into contact with the position where the scribe line S is formed on the glass ribbon R. However, the broken body 22 may also be brought into contact with a position above the scribe line S on the glass ribbon R (including the abutment described above).

[0153] In the above embodiment, a restricting roller 46 was used as a restricting member to restrict the vibration of the glass ribbon R, but the restricting member does not have to be in the shape of a roller, and may be, for example, a spherical body that rotates similarly to the restricting roller 46.

[0154] In the above embodiment, the regulating rollers 46 restrict the movement of the glass ribbon R by sandwiching it from both sides in the front-back direction. However, the regulating rollers 46 do not necessarily need to sandwich the glass ribbon R. That is, the gap between the pair of regulating rollers 46 may be made larger than the thickness of the glass ribbon R, so that the glass ribbon R only contacts the regulating rollers 46 when the glass ribbon R is moving.

[0155] In the above embodiment, the starting end S1 and ending end S2 of the scribe line S are located on the widthwise side of the first contact mark 41 of the glass ribbon R. However, the starting end S1 and ending end S2 of the scribe line S may be located within the first contact mark 41 or within the groove-shaped gap region 43. However, it is preferable that the starting end S1 and ending end S2 of the scribe line S are located on the widthwise side of the lug portion Rm of the glass ribbon R.

[0156] In the above embodiment (first embodiment), the measuring roller 13 is integrally attached to the first roller shaft 30, but the first roller shaft 30 may be fixed in place and the measuring roller 13 may be rotatably attached to the first roller shaft 30.

[0157] In the above embodiment (first embodiment), the measuring roller 13 is cantilevered, but the measuring roller 13 may also be attached to a first roller shaft 30 that is supported at both ends in the width direction. The same applies to the auxiliary roller 14.

[0158] In the above embodiment (second embodiment), two sensors 50 were arranged at different positions in the vertical direction, but three or more sensors 50 may be arranged at different positions in the vertical direction. Even in this case, only two sensors 50 are actually used, and if, for example, one of the sensors 50 being used malfunctions or becomes unusable due to reaching the end of its lifespan, the system can switch to using another sensor 50. This allows for continuous measurement of the glass ribbon R's movement speed without interruption. In this case, multiple movement speeds can be calculated from the signals of three or more sensors 50, the movement speed of the components of the cutting device 5 can be made to follow the movement speed of one of these speeds, and the remaining calculated movement speeds can be used to verify whether the one movement speed is accurate or not. [Explanation of Symbols]

[0159] 1 Manufacturing equipment 2 Molding equipment 3. Conveying device 4 Speed ​​measuring device 5 Cutting device 6 Molding furnace 7 Molded body 8 Edge rollers 9 Annealing furnace 10 Uncooled roller 11 Cooling room 12 Support rollers 13 Measuring rollers 14 Auxiliary rollers 15. Scribe device 16 Folding device 17 Scribe Cutter 19 Support (First Support Rotating Body) 22 Folded body 25 Support mechanism (support part) 27 Gripping member 41. First contact mark (contact point between the glass ribbon and the edge roller) 42. Second contact marks (contact area between the glass ribbon and the annealing roller and support roller) 45 Guide rollers 46. ​​Regulating member (regulating roller) 50 sensors Gm molten glass GP glass plate Lx: Distance between multiple sensors R Glass Ribbon R1 One end of the glass ribbon in the width direction (one end in the width direction) R2 The other end of the glass ribbon in the width direction (the end on the other side in the width direction) Surface (one side) of Ra glass ribbon Rb Glass ribbon back side (the other side) Cutting area of ​​Rc glass ribbon Rm Glass Ribbon Ears Effective area of ​​Rs glass ribbon Unusable area of ​​Rt glass ribbon Rv Glass ribbon lower end face (cut end face) Rz Glass ribbon width direction center (center position) S scribe line S1 scribe line starting point S2 scribe line termination

Claims

1. A glass plate manufacturing apparatus comprising: a molding apparatus for forming a glass ribbon from molten glass; a conveying apparatus for conveying the glass ribbon downward; a speed measuring apparatus for measuring the movement speed of the glass ribbon conveyed downward by the conveying apparatus; and a cutting apparatus for cutting out a single sheet of glass plate from the glass ribbon, The cutting apparatus comprises a scribe device that forms a scribe line extending along the width direction of the glass ribbon from one end to the other end in the width direction perpendicular to the transport direction of the glass ribbon, and a folding device that breaks the glass ribbon at the position where the scribe line is formed to obtain a single sheet of glass. The glass plate manufacturing apparatus is characterized in that the speed measuring device measures the movement speed of the region on one end side of the glass ribbon, rather than the center in the width direction.

2. The molding apparatus further comprises a molding body for forming the glass ribbon from the molten glass, and edge rollers for gripping both ends of the glass ribbon in the width direction as it descends from the molding body and feeding it downward. The glass plate manufacturing apparatus according to claim 1, wherein the speed measuring device measures the movement speed of the region of the glass ribbon that is on the central side in the width direction rather than the contact portion with the edge roller.

3. The glass ribbon has tabs at both ends in the width direction that are thicker than the central part in the width direction. The glass plate manufacturing apparatus according to claim 1, wherein the speed measuring device measures the movement speed of the region of the glass ribbon that is closer to the center in the width direction than the ear portion.

4. The glass plate manufacturing apparatus according to any one of claims 1 to 3, wherein the speed measuring device comprises a measuring roller that rotates in contact with the glass ribbon, and measures the moving speed of the glass ribbon based on the rotational speed of the measuring roller.

5. The glass plate manufacturing apparatus according to claim 4, wherein the measuring roller is a free roller.

6. The molded body is further provided with an annealing furnace for slowly cooling the glass ribbon below it, The conveying device includes an annealing roller for conveying the glass ribbon within the annealing furnace, The slow-cooling roller grips the area of ​​the glass ribbon that is closer to the center in the width direction than the contact portion with the edge roller. The glass plate manufacturing apparatus according to claim 2, wherein the speed measuring device measures the moving speed of the glass ribbon in a region excluding the contact portion with the annealing roller.

7. The glass plate manufacturing apparatus according to claim 6, wherein the speed measuring device measures the movement speed of the region of the glass ribbon that is on the central side in the width direction rather than the contact portion with the annealing roller.

8. The annealing furnace further comprises a cooling chamber for cooling the glass ribbon below it, The conveying device includes support rollers that support the glass ribbon in the cooling chamber, The support roller grips the area of ​​the glass ribbon that is closer to the center in the width direction than the contact portion with the edge roller. The glass plate manufacturing apparatus according to claim 6, wherein the speed measuring device sets the moving speed of the region of the glass ribbon excluding the contact portion with the support roller.

9. The glass plate manufacturing apparatus according to claim 8, wherein the speed measuring device measures the movement speed of the region of the glass ribbon that is on the central side in the width direction rather than the contact portion with the support roller.

10. The glass ribbon comprises an effective region located on the central side in the width direction and an ineffective region which is the entire area on the end side in the width direction from the effective region. The glass plate manufacturing apparatus according to any one of claims 1 to 3, wherein the speed measuring device measures the moving speed of the non-effective area.

11. The glass plate manufacturing apparatus according to claim 4, further comprising an auxiliary roller positioned on either side of the glass ribbon, corresponding to the measuring roller.

12. The glass plate manufacturing apparatus according to claim 11, wherein the auxiliary roller is a drive roller.

13. The glass plate manufacturing apparatus according to claim 12, wherein the rotational speed of the auxiliary roller is controlled to follow the moving speed of the glass ribbon measured by the measuring roller.

14. The glass plate manufacturing apparatus according to claim 11, wherein the measuring roller is positioned on one side of the glass ribbon, the auxiliary roller is positioned on the other side of the glass ribbon, and a pressing force is applied from the auxiliary roller to the measuring roller via the glass ribbon.

15. The glass plate manufacturing apparatus according to claim 14, further comprising: a scribe cutter that forms the scribe line on the other surface of the glass ribbon; and a support that contacts the one surface of the glass ribbon and supports the glass ribbon when the scribe cutter forms the scribe line.

16. The glass plate manufacturing apparatus according to claim 1 or 2, further comprising a guide roller for gripping the glass ribbon in a region of the glass ribbon that is on the other end side of the center in the width direction and at a height corresponding to the speed measuring device.

17. The glass plate manufacturing apparatus according to claim 4, wherein at least the outer circumference of the measuring roller is formed of heat-resistant rubber.

18. The glass plate manufacturing apparatus according to claim 1 or 2, wherein the speed measuring device measures the moving speed of the glass ribbon in an area below the conveying device and above the scribe device.

19. The glass plate manufacturing apparatus according to claim 18, further comprising a regulating member for regulating the vibration of the glass ribbon in a region below the speed measuring device and above the scribe device.

20. The glass plate manufacturing apparatus according to any one of claims 1 to 3, wherein the speed measuring device measures the moving speed of the glass ribbon in a non-contact manner.

21. The speed measuring device is positioned below the position where the folding device folds the glass ribbon and includes a plurality of sensors capable of detecting the presence or absence of the glass ribbon, the plurality of sensors being positioned at different locations in the vertical direction. A glass plate manufacturing apparatus according to claim 20, which calculates the moving speed of the glass ribbon using the time at which each of the plurality of sensors detects the position of the lower end surface of the glass ribbon formed by folding by the folding device, and the vertical distance between each of the plurality of sensors.

22. The glass plate manufacturing apparatus according to claim 20, wherein the cutting device moves downward in accordance with the moving speed of the glass ribbon measured by the speed measuring device.

23. A method for manufacturing a glass plate, comprising: a molding step of forming a glass ribbon from molten glass; a conveying step of conveying the glass ribbon downward; a speed measuring step of measuring the movement speed of the glass ribbon during the conveying step; and a cutting step of cutting out a single sheet of glass plate from the glass ribbon, The cutting process comprises a scribing step of forming a scribe line extending along the width direction of the glass ribbon from one end to the other end in the width direction perpendicular to the transport direction of the glass ribbon, and a folding step of folding the glass ribbon at the position where the scribe line is formed to obtain a single sheet of glass. A method for manufacturing a glass plate, characterized in that the speed measurement step measures the movement speed of the region on one end side of the glass ribbon, rather than the center in the width direction.

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