Glass sheet production method

Abstract

This glass sheet production method, which includes an end face processing step in which while moving a grindstone 12 and a glass sheet G relative to each other, the grindstone 12 is brought into contact with a first end face Ga1 of the glass sheet G extending in the direction of the relative movement, and the end face Ga1 is processed comprises: an abnormality detection step for detecting an abnormality of the glass sheet G by bringing a contact 6 of an abnormality detection device 4, which moves relative to the glass sheet G together with the grindstone 12 and can be brought into contact with the first end face Ga1 of the glass sheet G before the grindstone 12, into contact with at least one end face among the first end face Ga1 of the glass sheet G and a second end face Gb2 orthogonal to the first end face Ga1; and a stop step for stopping the end face processing step when an abnormality of the glass sheet G is detected in the abnormality detection step.

Description

Glass plate manufacturing method

[0001] The present invention relates to a method for manufacturing a glass sheet, and more particularly to a method for manufacturing a glass sheet including an edge processing step.

[0002] In the manufacturing process of glass substrates used for liquid crystal displays and the like, one or more glass plates are cut out from a large glass blank (preformed blank). The edge surfaces of the cut glass plates are usually subjected to grinding (rough processing) and polishing (finishing processing). When such edge processing of the glass plate is performed, abnormalities may occur in the glass plate.

[0003] One example of a measure to address abnormalities in glass sheets is disclosed in Patent Document 1. In this document, abnormal irregularities occurring on the edge surface of a glass sheet are considered to be abnormalities in the glass sheet. This document also discloses that, when a processing tool (e.g., a grinding wheel) is pressed against the edge surface of the glass sheet to perform an edge surface processing step, the processing tool is caused to detect the abnormal irregularities, and upon detection, the processing tool is moved away from the edge surface of the glass sheet.

[0004] Another example of a solution is disclosed in Patent Document 2. In this document, misalignment of the edge surface of a glass plate is considered to be an abnormality of the glass plate. This document also discloses a method in which a contactor that can come into contact with the edge surface of the glass plate before a processing tool (grinding wheel) detects the misalignment of the edge surface of the glass plate, adjusts the position of the processing tool according to the detected misalignment, and then performs the edge processing step using the processing tool.

[0005] Patent No. 6978724 Patent No. 7108240

[0006] According to the solution disclosed in Patent Document 1, an abnormality in the glass plate is detected when a processing tool that is pressed strongly against the edge face of the glass plate reaches an abnormal unevenness occurring on the edge face. Therefore, at the time when the abnormality in the glass plate is detected, there is a risk that the glass plate will be broken or otherwise damaged, with the unevenness serving as the starting point.

[0007] On the other hand, as disclosed in Patent Document 2, the measure of performing the edge processing step by adjusting the position of the processing tool in accordance with the positional deviation of the edge of the glass sheet is prone to errors in the adjustment of the position of the processing tool, making it difficult to perform high-precision edge processing. Moreover, when the positional deviation of the edge of the glass sheet is large, it may not be possible to address the problem by simply adjusting the position of the processing tool.

[0008] From the above perspective, the object of the present invention is to prevent damage to the glass plate when detecting an abnormality in the glass plate, while enabling the edge processing process to be properly carried out after detecting an abnormality in the glass plate.

[0009] (1) A first aspect of the present invention, which has been invented to solve the above-mentioned problems, is a method for manufacturing a glass plate, which includes an edge processing step in which a processing tool and a glass plate are moved relative to each other, and the processing tool is brought into contact with an edge surface of a first side of the glass plate extending in the direction of relative movement to process the edge surface; the method is characterized by including an abnormality detection step in which a contactor of an abnormality detection device, which moves relative to the glass plate together with the processing tool and is configured to contact the edge surface of the first side of the glass plate before the processing tool does, is brought into contact with at least one of the edge surface of the first side and the edge surface of a second side orthogonal to the edge surface of the first side of the glass plate, to detect an abnormality in the glass plate; and an abort step in which an abnormality in the glass plate is detected in the abnormality detection step.

[0010] With this configuration, since the detection of an abnormality in the glass sheet is performed by the contact of the abnormality detection device, it is not necessary to apply a strong pressing force to the glass sheet as with a processing tool. Moreover, since the edge processing process is stopped when an abnormality in the glass sheet is detected, when the edge processing process is performed again thereafter, a new edge processing process can be performed regardless of the abnormality in the glass sheet. This prevents damage to the glass sheet when an abnormality in the glass sheet is detected, and allows the edge processing process to be performed properly after the abnormality in the glass sheet is detected.

[0011] (2) In the configuration of (1) above, the abnormality of the glass plate is a convex or concave portion partially occurring on the end face of the first side of the glass plate, and an abnormality detection process is carried out during the end face processing process, and in the abnormality detection process, if the contactor climbs onto the convex portion or enters the concave portion, it may be determined that the glass plate is abnormal.

[0012] In this way, a protrusion or recess that occurs partially on the edge face of the glass plate can be properly detected as an abnormality in the glass plate.

[0013] (3) In the configuration of (2) above, in the stopping step, the processing tool is retracted to a position where it does not interfere with the glass plate, and after the stopping step is performed, the glass plate may be discarded or reused by removing the convex or concave portions.

[0014] In this way, as soon as the contactor detects the presence of a convex or concave portion, the processing tool can be retracted to a position where it does not interfere with the glass plate, thereby quickly preventing unnecessary edge processing by the processing tool.

[0015] (4) In any of the above configurations (1) to (3), the contact of the abnormality detection device may have a smaller contact pressure with the end face of the first side of the glass plate than the processing tool.

[0016] This makes it possible to more reliably prevent damage to the glass plate when detecting an abnormality in the glass plate.

[0017] (5) In any of the configurations (1) to (4) above, the abnormality detection device may include a swingable arm member, the contactor is attached to the tip of the arm member and is biased toward the end face of the first side of the glass plate, the glass plate is set in a fixed position, and the processing tool and the arm member may be held on a single movable base and move together.

[0018] In this way, the end face processing step and the abnormality detection step can be smoothly performed by a compact device.

[0019] (6) In any of the configurations (1) to (5) above, the edge processing step may be performed by bringing a pair of processing tools into contact with the edge surfaces of a pair of first sides of the glass plate, and an abnormality detection step may be performed before the edge processing step is performed.

[0020] In this way, abnormalities in the posture or position of the glass plate can be detected.

[0021] (7) In the configuration of (6) above, the abnormality in the glass plate is an abnormality in the position of the glass plate in a direction along the first side, and in the abnormality detection process, a case in which a pair of contacts contact an end face of one of the second sides of the glass plate at the same position in the direction along the first side and the position is different from the normal position may be determined to be an abnormality in the glass plate.

[0022] In this way, in the abnormality detection step, an abnormality in the position of the glass plate in the direction along the first side is appropriately detected as an abnormality in the glass plate.

[0023] (8) In the configuration of (7) above, in the stopping step, the relative movement between the pair of processing tools and the glass plate may be stopped, and after the stopping step is performed, the positional abnormality may be corrected and the edge processing step may be performed on the glass plate.

[0024] In this way, the stopping step is performed properly, and the subsequent edge processing step is also performed properly. In this case, if the stopping step is performed when an abnormality in the glass sheet is detected in the abnormality detection step, that is, when the pair of contacts are in contact with the edge of the second side of the glass sheet, the relative movement of the processing tool and the pair of contacts can be stopped before the processing tool reaches the edge of the first side of the glass sheet. This appropriately prevents the edge of the first side of the glass sheet from being improperly processed by the processing tool.

[0025] (9) In the configuration of (6) above, the abnormality in the glass plate is an abnormality in the position of the glass plate in the direction along the second side, and in the abnormality detection process, when the pair of contacts are in contact with the end faces of the pair of first sides of the glass plate, the glass plate may be determined to be abnormal if the positions of the pair of contacts in the direction along the second side of the glass plate are both different from the normal positions and the distance between the pair of contacts is the same as the normal distance.

[0026] In this way, in the abnormality detection step, an abnormality in the position of the glass plate in the direction along the second side is appropriately detected as an abnormality in the glass plate.

[0027] (10) In the configuration of (9) above, in the stopping step, the pair of processing tools may be retracted to a position where they do not interfere with the glass plate, and after the stopping step is performed, the positional abnormality may be corrected and the edge processing step may be performed on the glass plate.

[0028] In this way, the stopping step is properly performed, and the subsequent edge processing step is also properly performed. In this case, after an abnormality in the glass sheet is detected in the abnormality detection step, the stopping step can be performed to retract the processing tool before the processing tool reaches the edge of the first side of the glass sheet. This can appropriately avoid the problem of the processing tool improperly processing the edge of the first side of the glass sheet.

[0029] (11) In the configuration of (6) above, the abnormality of the glass plate is a deviation in the dimensions of the glass plate in the direction along the second side, and in the abnormality detection process, when the pair of contacts are in contact with the end faces of the pair of first sides of the glass plate, a case in which the spacing between the pair of contacts is different from the normal spacing may be determined to be an abnormality of the glass plate.

[0030] In this way, in the abnormality detection step, deviation in the size of the glass plate in the direction along the second side is appropriately detected as an abnormality in the glass plate.

[0031] (12) In the configuration of (11) above, in the stopping step, the pair of processing tools may be retracted to a position where they do not interfere with the glass plate, and after the stopping step is performed, the glass plate may be discarded or the size of the glass plate may be adjusted and reused.

[0032] In this way, the interruption step is properly performed, and the subsequent edge processing step is also properly performed. In this case, as in the case of the above-mentioned configuration (10), it is possible to properly avoid the problem of the edge of the first side of the glass sheet being improperly processed by the processing tool.

[0033] (13) In the configuration of (6) above, the abnormality of the glass plate is a misalignment of the glass plate such that the glass plate is in an inclined position, and in the abnormality detection process, the glass plate may be determined to be abnormal when one contact and the other contact of a pair of contacts contact an end face of one second side of the glass plate at different positions in the direction along the first side, or when one contact contacts an end face of one second side of the glass plate and the other contact contacts an end face of the first side of the glass plate.

[0034] In this way, in the abnormality detection step, a deviation in the orientation of the glass plate that causes it to be in an inclined orientation is appropriately detected as an abnormality in the glass plate.

[0035] (14) In the configuration of (13) above, in the stopping step, the relative movement between the pair of processing tools and the glass plate may be stopped, and after the stopping step is performed, the misalignment of the glass plate may be corrected and the edge processing step may be performed on the glass plate.

[0036] In this way, the stopping step is performed properly, and the subsequent edge processing step is also performed properly. In this case, if the stopping step is performed when an abnormality in the glass sheet is detected in the abnormality detection step, that is, when at least one of the pair of contacts is in contact with the edge of the second side of the glass sheet, the relative movement of the processing tool and the contacts can be stopped before the processing tool reaches the edge of the first side. This appropriately prevents the edge of the first side of the glass sheet from being improperly processed by the processing tool.

[0037] According to the present invention, it is possible to properly execute the edge processing step after detecting an abnormality in the glass plate while preventing breakage of the glass plate when detecting an abnormality in the glass plate.

[0038] FIG. 1 is a plan view showing the overall configuration of a glass sheet manufacturing apparatus used to implement a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 2 is a plan view showing the configuration of a main part of a glass sheet manufacturing apparatus used to implement a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 3 is a plan view showing the operation of a main part of a glass sheet manufacturing apparatus used to implement a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 4 is a plan view showing the configuration of a main part of a glass sheet manufacturing apparatus used to implement a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 5 is a schematic plan view showing a state of implementation of a first example of a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 6 is a schematic plan view showing a state of implementation of a second example of a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 7 is a schematic plan view showing a state of implementation of a third example of a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 8 is a schematic plan view showing a state of implementation of a fourth example of a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 9 is a schematic plan view showing a state of implementation of a fifth example of a method for manufacturing a glass sheet according to an embodiment of the present invention; FIG. 10 is a schematic plan view showing a state of implementation of a sixth example of a method for manufacturing a glass sheet according to an embodiment of the present invention; and FIG. 11 is a schematic plan view showing a state of implementation of a seventh example of a method for manufacturing a glass sheet according to an embodiment of the present invention.

[0039] Hereinafter, a method for manufacturing a glass plate according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0040] 1 is a plan view showing a state in which a glass sheet manufacturing method according to an embodiment of the present invention is carried out using a glass sheet manufacturing apparatus 1. First, the glass sheet manufacturing apparatus 1 will be described with reference to the drawing.

[0041] The glass sheet manufacturing apparatus 1 includes two processing units 2. Each of these processing units 2 includes a movable base 3, an abnormality detection device 4, and two edge processing devices 5. In this embodiment, the two processing units 2 are configured to move in the X direction in the figure with a rectangular glass sheet G set in a fixed position.

[0042] The two processing units 2 are arranged to correspond to end faces Ga1 of a pair of first sides Ga along the X direction of the glass sheet G (hereinafter referred to as first end faces Ga1). The abnormality detection devices 4 and two edge face processing devices 5 of the two processing units 2 are both held on a single movable base 3. Therefore, the abnormality detection devices 4 and two edge face processing devices 5 of the two processing units 2 are configured to move integrally in the X direction. When the two processing units 2 move in the X direction, one abnormality detection device 4 first contacts the first edge face Ga1 of the glass sheet G, and then the two edge face processing devices 5 contact the first edge face Ga1 of the glass sheet G in turn.

[0043] Since the upper and lower processing units 2 in the figure have substantially the same configuration, the following description will be given taking the lower processing unit 2 as an example.

[0044] The abnormality detection device 4 in the processing unit 2 is configured to contact not only the first end face Ga1 of the glass sheet G but also one end face Gb2 (hereinafter referred to as the second end face Gb2) of the end faces Gb1, Gb2 of a pair of second sides Gb along the Y direction perpendicular to the X direction. The second end face Gb2 is the rear end face of the end faces Gb1, Gb2 in the X direction (movement direction).

[0045] More specifically, the anomaly detection device 4 includes a roller 6, which is a contactor that contacts the second end face Gb2 of the glass sheet G and then contacts the first end face Ga1. As shown in FIG. 2 , the contactor 6 is configured as a cylindrical roller in this embodiment. The diameter of the roller 6 is 10 to 500 mm. As shown in the figure, the roller 6 is attached to the tip of an arm member 7 via a support shaft 8. The roller 6 may be a free roller that rotates around the support shaft 8, but in this embodiment, it is fixed to the tip of the arm member 7. The material of at least the outer periphery of the roller 6 is preferably resin, but may also be metal such as aluminum, hard rubber, or the like.

[0046] Furthermore, the abnormality detection device 4 includes a servo motor 9 that swings the arm member 7 so as to change the angle. The servo motor 9 has a motor shaft 9a that can rotate in both forward and reverse directions. The base end of the arm member 7 is connected to the motor shaft 9a of the servo motor 9. Therefore, the arm member 7 can swing within a plane along the main surface G1 of the glass sheet G as the motor shaft 9a rotates.

[0047] The arm member 7 is configured to change its posture between an upright posture in which it extends in a direction along the second edge surface Gb2 of the glass sheet as shown by the chain line in the figure, and an inclined posture in which it extends in an inclined direction as shown by the solid line in the figure, in accordance with the rotation of the motor shaft 9a of the servo motor 9. The arm member 7 is also biased by the servo motor 9 in a direction in which it transitions from the inclined posture to the upright posture. In this case, when the arm member 7 is in the upright posture, a stopper (not shown) restricts the arm member 7 from swinging clockwise.

[0048] With this configuration, as shown by the solid line in the figure, while the abnormality detection device 4 moves in the X direction in conjunction with the movement of the machining unit 2, the roller 6 is pressed against the first end face Ga1 of the glass sheet G while being urged toward the first end face Ga1 by the arm member 7. In this state, the roller 6 moves over the first end face Ga1. Also, as shown by the dotted line in the figure, when the abnormality detection device 4 moves in the X direction from a state in which the roller 6 is in contact with the second end face Gb2 of the glass sheet G, the roller 6 is pressed against the second end face Gb2 of the glass sheet G while being urged toward the second end face Gb2 by the arm member 7. From this state, the arm member 7 gradually tilts as the roller 6 moves over the second end face Gb2.

[0049] In this case, the X-direction position and Y-direction position of the roller 6 relative to the machining unit 2 are calculated from the angle α formed between a line L1 along the Y direction and the center line L2 of the arm member 7 (in the illustrated example, the line L2 connecting the support shaft 8 and the motor shaft 9a). In this embodiment, the base end of the arm member 7 is directly connected to the motor shaft 9a of the servo motor 9, so the angle α is the rotation angle of the motor shaft 9a. In this case, the position of the roller 6 is calculated by the control unit 10 of the servo motor 9. The servo motor 9 is fixed to an assembly base 11.

[0050] 3 illustrates the states of the roller 6 and the arm member 7 as the abnormality detection device 4 moves in the X direction in conjunction with the movement of the machining unit 2. As indicated by the solid line in the figure, the arm member 7 is maintained in an upright position when the roller 6 contacts the second end face Gb2 of the glass sheet G. From this state, the roller 6 climbs over the corner Gc between the second end face Gb2 and the first end face Ga1 of the glass sheet G as indicated by the symbol A in the figure, and reaches the first end face Ga1 of the glass sheet G as indicated by the symbol B in the figure. When the roller 6 climbs over the corner Gc and when it reaches the first end face Ga1, the arm member 7 assumes an inclined position.

[0051] As shown in FIG. 4 , each of the two edge processing devices 5 includes a motor 13 that rotates a grinding wheel 12 serving as a processing tool, a support member 14 that rotatably supports the grinding wheel 12, and a first actuator (not shown) that generates a driving force for the grinding wheel 12 to press against the first edge Ga1 of the glass sheet G. Furthermore, each of the two edge processing devices 5 is moved between a position indicated by a solid line in the figure and a position indicated by a dashed line in the figure by the operation of a second actuator (not shown). The solid line indicates a state in which the grinding wheel 12 is processing the first edge Ga1 of the glass sheet G. The dashed line indicates a state in which the grinding wheel 12 is retracted from the first edge Ga1 of the glass sheet G. In this case, each of the two edge processing devices 5 is guided by a guide member (not shown). These guide members are fixed to the movable base 3. The two edge surface processing devices 5 both move linearly along the Y direction on a plane parallel to the surface 3a of the movable base 3. The two edge surface processing devices 5 can also move independently of each other.

[0052] The motor 13 may be, but is not limited to, a synchronous motor, an induction motor, a servo motor, etc. The first actuator may be, but is not limited to, a coreless linear motor from the viewpoint of compactness, etc. The second actuator may be, but is not limited to, an air cylinder, a linear cylinder using a ball screw mechanism, etc.

[0053] The grinding wheels 12 that first process the first end surface Ga1 of the glass sheet G are used for grinding (rough processing) and have a large pressing force (contact pressure) against the first end surface Ga1. The grinding wheels 12 that subsequently process the first end surface Ga1 are used for polishing (finish processing) and have a smaller pressing force (contact pressure) against the first end surface Ga1 than the grinding wheels 12. These grinding wheels 12 are all controlled so that the pressing force against the first end surface Ga1 is constant. Furthermore, the pressing force of these grinding wheels 12 against the first end surface Ga1 is greater than the pressing force of the roller 6 described above against the first end surface Ga1. The grain size of the abrasive grains in the polishing grinding wheels 12 is the same as or larger than the grain size of the abrasive grains in the grinding grinding wheels 12. The grain size of the abrasive grains in the grinding wheel 12 can be, for example, #100 to #1000, and the grain size of the abrasive grains in the polishing wheel 12 can be, for example, #200 to #3000. The diameter of each of these grinding wheels 12 is, for example, 100 to 200 mm.

[0054] The direction in which these grinding wheels 12 move between the processing position P1 and the retracted position P2 is the Y direction. The lower limit of the distance M1 between the processing position P1 of these grinding wheels 12 when processing the first end face Ga1 of the glass sheet G and the retracted position P2 of these grinding wheels 12 when retracted from the first end face Ga1 of the glass sheet G is preferably 50 mm, more preferably 80 mm. The upper limit of this distance M1 is preferably 500 mm, more preferably 300 mm.

[0055] 5, the assembly base 11 of the abnormality detection device 4 is fixed to the movable base 3. Therefore, the abnormality detection device 4 and the two end face processing devices 5 are configured to move integrally in the X direction.

[0056] The glass sheet manufacturing apparatus 1 also includes a control device (not shown). The control device includes a storage unit that stores various pieces of positional information, a calculation unit that calculates the positions of the above-described components based on the various pieces of positional information, and a main control unit that controls the operations of the components based on the positions.

[0057] Next, a method for manufacturing a glass sheet using the glass sheet manufacturing apparatus 1 having the above configuration will be described.

[0058] This manufacturing method includes a preparation step of setting a glass sheet G in a fixed position, an edge processing step of processing a pair of first edge surfaces Ga1 of the glass sheet G, an abnormality detection step of detecting an abnormality in the glass sheet G, and a cancellation step of canceling the edge processing step when an abnormality is detected in the glass sheet G. Note that after the edge processing step, steps such as cleaning, inspection, and packaging of the glass sheet G may be performed.

[0059] In the preparation step, the glass sheet G is fixed by any method, such as suction, on a mounting table (e.g., a surface plate) arranged in a fixed position. At this time, the processing unit 2 waits upstream of the second end surface Gb2 of the glass sheet G (on the left side in FIG. 1 ). In the following description, this waiting position is referred to as the initial position. The initial position is stored as position information in the memory unit of the control device. The processing position P1 and the retreat position P2 described above are also stored as position information in the memory unit of the control device.

[0060] The glass sheet G is obtained by obtaining a forming base plate by a predetermined forming method and then cutting the forming base plate to a predetermined size. Examples of forming methods that can be used include downdraw methods such as the overflow downdraw method, slot downdraw method, and redraw method, as well as the float method. Among these, the overflow downdraw method is preferred because it produces high-quality surfaces on both sides. The glass sheet G is cut out, for example, by forming scribe lines on the forming base plate and then bending and breaking the forming base plate along the scribe lines. In this case, the pair of first end faces Ga1 and the pair of second end faces Gb2 of the glass sheet G are surfaces formed by bending and breaking. The glass sheet G is used, for example, as a glass substrate for flat panel displays such as liquid crystal displays.

[0061] The glass sheet G has a rectangular plate shape. The thickness of the glass sheet G is, for example, preferably 0.05 to 10 mm, and more preferably 0.2 to 0.7 mm. Of course, the glass sheet G to which the present invention can be applied is not limited to the above-mentioned form. For example, the present invention can also be applied to glass sheets having shapes other than rectangular (e.g., polygonal) and glass sheets having thicknesses outside the range of 0.05 to 10 mm.

[0062] First to seventh examples of this manufacturing method (particularly, first to seventh examples of the end face processing step, the abnormality detection step, and the suspension step) will be described below.

[0063] 6 is a schematic plan view showing a first example of the manufacturing method. As shown in FIG. 6, in this first example, an abnormality in the glass sheet G occurs in one of the first end faces Ga1 (the lower first end face Ga1 in the figure), resulting in a recess Gx such as a crack or chip. This recess Gx cannot be removed by the grinding wheel 12.

[0064] Furthermore, in this first example, the abnormality detection process is executed during the edge surface processing process, and the abort process is executed after the abnormality detection process is executed. Specifically, in the edge surface processing process, as the processing unit 2 moves in the X direction, the two grinding wheels 12 sequentially grind and polish the first edge surface Ga1, as shown by the solid lines in the figure. Prior to this, the roller (contactor) 6 moves in contact with the first edge surface Ga1. At this time, the abnormality detection process is executed. Then, as the roller 6 enters the recess Gx, the abort process is executed when the position of the roller 6 in the Y direction is displaced from the normal position toward the center of the glass sheet G in the Y direction. Here, "displaced from the normal position toward the center of the glass sheet G in the Y direction" strictly means that the roller 6 has been displaced from the normal position toward the center of the glass sheet G in the Y direction by more than a predetermined threshold. This threshold is set to 0.1 to 10 mm. The normal position and threshold are stored as position information in the memory unit of the control device. The position of the roller 6 in the Y direction here is the position of the roller 6 in the Y direction calculated by the control unit 10 of the servo motor 9 from the angle α.

[0065] In the stopping step, the two grinding wheels 12 are retracted from the processing position P1 to the retracted position P2. At this time, the roller 6 may also be retracted to a retracted position away from the first end face Ga1. However, since the pressing force from the roller 6 against the first end face Ga1 is significantly smaller than that of the two grinding wheels 12, the roller 6 may be left as is. This prevents problems such as damage to the glass sheet G originating from the recess Gx of the first end face Ga1. Furthermore, the retraction of the grinding wheels 12 to the retracted position P2 is performed in the shortest time possible, thereby improving productivity. Furthermore, the movement of the processing unit 2 in the X direction may be stopped at the same time as the retraction of the grinding wheels 12 to the retracted position P2, and the processing unit 2 may be returned to its initial position.

[0066] After the abort step is performed, the glass plate G is discarded. Alternatively, the recess Gx on the first end face Ga1 may be removed to form a smaller glass plate (product) for reuse.

[0067] FIG. 7 is a schematic plan view showing the implementation of a second example of the manufacturing method. As shown in the figure, this second example differs from the first example described above in that an abnormality in the glass sheet G is a convex portion Gy, such as an uncut portion, on one of the first end faces Ga1 (the lower first end face Ga1 in the figure). This convex portion Gy cannot be removed by the grindstone 12. Therefore, according to this second example, the stopping step is executed when the Y-direction position of the roller 6 is displaced from the normal position to the outside of the glass sheet G in the Y-direction as the roller 6 rides over the convex portion Gy. Here, "displaced from the normal position to the outside of the glass sheet G in the Y-direction" strictly means that the glass sheet G is displaced from the normal position to the outside of the Y-direction by more than a predetermined threshold. This threshold is set to 0.1 to 10 mm. Other details are the same as those described in the first example described above.

[0068] FIG. 8 is a schematic plan view showing the implementation of a third example of this manufacturing method. The dotted line in FIG. 8 indicates the contour shape of the glass sheet G when there is no abnormality (the same applies to the following FIGS. 9 to 12). In this third example, an abnormality in the glass sheet G is detected when the positions of the pair of second end faces Gb2 of the glass sheet G are both misaligned by a dimension a in the X direction. In other words, the glass sheet G is misaligned by a dimension a on the rear side in the movement direction of the processing unit 2. In this third example, an abnormality detection process is performed before the edge processing process (the same applies to the following fourth to seventh examples). The abnormality detection process is performed during the process in which the rollers 6 contact the second end face Gb2 of the glass sheet G as the processing unit 2 moves from its initial position in the X direction, as shown in FIG. Specifically, in this abnormality detection process, an abnormality in the glass sheet G is detected when the pair of rollers 6 contact the second end face Gb2 of the glass sheet G at the same position but that position is different from the normal position. The term "same position" means, strictly speaking, that the difference between the two positions is below a predetermined threshold. This threshold is set, for example, to 5 mm or less, preferably 2 mm or less. Furthermore, the term "different from the normal position" means, strictly speaking, that the difference from the normal position exceeds a predetermined threshold. This threshold is set, for example, to 10 mm or more, preferably 15 mm or more. The normal position and the two thresholds are stored as position information in the memory unit of the control device. The position when the abnormality detection process is performed can also be determined by detecting time. In this abnormality detection process, if the pair of rollers 6 contact the second end surface Gb2 of the glass sheet G at the same time but at a different time from the normal time, an abnormality in the glass sheet G is detected. The term "same time" means, strictly speaking, that the difference between the two times is below a predetermined threshold. This threshold can be calculated from the threshold at the "same position" according to the movement speed of the processing unit 2. Furthermore, the term "different from the normal time" means, strictly speaking, that the difference from the normal time exceeds a predetermined threshold. This threshold value can also be calculated from the threshold value in the case where the position is different from the normal position described above, depending on the movement speed of the machining unit 2. Here, the position of the roller 6 in the X direction is determined with reference to the initial position.Therefore, the X-direction position of the roller 6 is determined based on the X-direction position of the processing unit 2, which is determined by the movement distance from the initial position, and the X-direction position of the roller 6 relative to the processing unit 2, which is determined by the control unit 10 of the servo motor 9 using the angle α. In this third example, when the roller 6 contacts the second end face Gb2 of the glass sheet G, the angle α becomes 0° or approximately 0°. As the processing unit 2 further moves in the X-direction, the roller 6 moves along the second end face Gb2, increasing the angle α. That is, whether or not a positional deviation occurs in the X-direction can be determined from the position where the angle α begins to change from 0° and the normal position stored in the memory unit of the control device. If the above-mentioned abnormality of the glass sheet G is detected in the abnormality detection process, the movement of the pair of processing units 2 in the X-direction is stopped in the interruption process. After the interruption process is performed, the pair of processing units 2 is returned to the initial position, the above-mentioned positional deviation of the glass sheet G is corrected, and the edge processing process is then performed on the pair of first end faces Ga1 of the glass sheet G. In this way, when the pair of rollers 6 are in contact with the second end surface Gb2 of the glass sheet G, the movement of the pair of processing units 2 in the X direction is stopped, thereby allowing sufficient time to avoid the problem of the pair of first end surfaces Ga1 of the glass sheet G being inappropriately ground and polished by the grinding wheels 12. This makes it possible to increase the movement speed of the processing units 2 in the X direction, thereby improving productivity.

[0069] In the above third example, we have explained the case where a positional deviation of the glass sheet G occurs on the rear side of the movement direction of the processing unit 2, but this third example can also be applied in the same manner when a positional deviation of the glass sheet G occurs on the front side of the movement direction of the processing unit 2.

[0070] FIG. 9 is a schematic plan view showing a fourth example of the manufacturing method. In this fourth example, an abnormality in the glass sheet G is detected when the positions of the pair of first end faces Ga1 of the glass sheet G are misaligned by a dimension b in the same direction along the Y direction. In other words, the glass sheet G is misaligned by a dimension b toward the lower side in the figure. The abnormality detection process is performed when the processing unit 2 moves from the initial position in the X direction, after the rollers 6 contact the second end faces Gb2 of the glass sheet G as shown by the dashed line in the figure, and then reach the first end faces Ga1 of the glass sheet G as shown by the solid line in the figure. Specifically, in this abnormality detection process, when the pair of rollers 6 contact the pair of first end faces Ga1 of the glass sheet G, if the positions of the pair of rollers 6 in the Y direction are both different from the normal positions and the spacing between the pair of rollers 6 is the same as the normal spacing, the glass sheet G is determined to be abnormal. Strictly speaking, the term "different from the normal positions" means that the positions are different from the normal positions by more than a predetermined threshold. This threshold is set, for example, to 10 mm or more, preferably 15 mm or more. The phrase "same as the normal spacing" strictly means that the distance is less than a predetermined threshold relative to the normal spacing. This threshold is set, for example, to 5 mm or less, preferably 2 mm or less. The normal position, normal spacing, and two thresholds are stored as position information in the memory of the control device. In this case, the Y-direction positions of the pair of rollers 6 when in contact with the pair of first end surfaces Ga1 of the glass sheet G are calculated from the angle α by the control unit 10 of each servo motor 9. Here, the Y-direction position of the processing unit 2 is always constant. Therefore, in order to recognize the Y-direction position of the rollers 6, it is not necessary to consider the Y-direction position of the processing unit 2. The X-direction positions of the pair of rollers 6 when determining whether the glass sheet G is misaligned in the same direction along the Y direction are positions when they are spaced apart in the X direction by a predetermined length M2 (e.g., 10 to 50 mm) from the corner Gc of the glass sheet G. If the above-mentioned abnormality of the glass sheet G is detected during this determination, all of the grinding wheels 12 are retracted to the retracted position P2 in the abort step. In this case, when the pair of rollers 6 is spaced apart from the corner Gc of the glass sheet G in the X direction by the above-mentioned predetermined length M2, none of the grinding wheels 12 has reached the pair of first end faces Ga1 of the glass sheet G.Therefore, by retracting all grinding wheels 12 to the retracted position P2 at this time, it is possible to avoid the problem of the pair of first end faces Ga1 of the glass sheet G being inappropriately ground and polished by the grinding wheels 12. After the execution of this suspension step, the pair of processing units 2 are returned to their initial positions, the above-mentioned positional deviation of the glass sheet G is corrected, and then the edge processing step is performed on the pair of first end faces Ga1 of the glass sheet G. Alternatively, even after the execution of the suspension step, the processing units 2 may be continuously moved to the movement end position and then returned to their initial positions, the above-mentioned positional deviation of the glass sheet G is corrected, and the edge processing step may be performed on the pair of first end faces Ga1 of the glass sheet G.

[0071] In the above fourth example, we have described a case where the glass sheet G is misaligned on the lower side in Figure 9, but this fourth example can also be applied in the same manner to a case where the glass sheet G is misaligned on the upper side in Figure 9.

[0072] FIG. 10 is a schematic plan view showing a fifth example of the manufacturing method. In this fifth example, an abnormality in the glass sheet G is detected when one of the first end faces Ga1 of the glass sheet G is misaligned by a distance c away from the center of the glass sheet G in the Y direction, and the other of the first end faces Ga1 is misaligned by a distance d away from the center of the glass sheet G in the Y direction. In other words, the glass sheet G has a dimensional deviation along the Y direction. The abnormality detection process is performed when the processing unit 2 moves from the initial position in the X direction, after the rollers 6 contact the second end face Gb2 of the glass sheet G as shown by the dashed line in the figure, and then reach the first end face Ga1 of the glass sheet G as shown by the solid line in the figure. Specifically, in this abnormality detection process, a difference in the distance between the pair of rollers 6 when the pair of rollers 6 contact the pair of first end faces Ga1 of the glass sheet G is detected as an abnormality in the glass sheet G. Strictly speaking, the phrase "when the spacing differs from the normal spacing" means when the spacing differs from the normal spacing by more than a predetermined threshold. This threshold is set, for example, to 0.5 mm or more, preferably 1 mm or more. The normal spacing and threshold are stored as position information in the memory of the control device. In this case, the Y-direction positions of the pair of rollers 6 when in contact with the pair of first end surfaces Ga1 of the glass sheet G are determined in the same manner as in the fourth example described above. The X-direction positions of the pair of rollers 6 when determining whether the glass sheet G is abnormal are also determined in the same manner as in the fourth example described above. Furthermore, if the abnormality of the glass sheet G is detected in the abnormality detection step, the stopping step involves retracting all grinding wheels 12 to the retracted position P2, and the timing of retracting all grinding wheels 12 is the same as described in the fourth example described above. Therefore, in this fifth example, the problem of the pair of first end surfaces Ga1 of the glass sheet G being improperly ground and polished by the grinding wheels 12 can be avoided. In this fifth example, the glass sheet G is discarded after the stopping step is performed. Therefore, after the abort process is performed, the processing unit 2 is returned to its initial position (including the case where it is returned to the initial position via the end position of movement), and all grinding wheels 12 are returned to the processing position P1, and then the processing unit 2 is moved again in the X direction, and the end surface processing process is performed on a pair of first end surfaces Ga1 of the subsequent glass sheet G that is free of abnormalities.In addition to being discarded, the glass plate G may be reused by adjusting its size.

[0073] In the above fifth example, we have described a case where the length of the glass plate G along the Y direction is longer than the normal length, but this fifth example can also be applied in the same manner when the length of the glass plate G along the Y direction is shorter than the normal length.

[0074] FIG. 11 is a schematic plan view showing a sixth example of the manufacturing method. In this sixth example, an abnormality in the glass sheet G is detected when a pair of first end faces Ga1 and a pair of second end faces Gb2 of the glass sheet G are inclined. In other words, the glass sheet G is misaligned and in an inclined position. The abnormality detection process is performed when the pair of rollers 6 contact the second end faces Gb2 of the glass sheet G as the processing unit 2 moves from the initial position in the X direction. In this abnormality detection process, a difference in the positions of one roller 6 and the other roller 6 when they contact the second end faces Gb2 is determined to be an abnormality in the glass sheet G. Strictly speaking, the "different positions" refers to a difference between the position of one roller 6 when it contacts the second end faces Gb2 and the position of the other roller 6 when it contacts the second end faces Gb2 that exceeds a predetermined threshold. This threshold is set to, for example, 0.5 mm or more, preferably 1 mm or more. This threshold is stored as position information in the memory unit of the control device. The position when the abnormality detection process is performed can also be determined by detecting time. In this case, in the abnormality detection process, if the timings at which one roller 6 and the other roller 6 contact the second edge surface Gb2 of the glass sheet G differ, it is determined that the glass sheet G is abnormal. Strictly speaking, the "different timings" means that the timings differ by more than a predetermined threshold. This threshold can be calculated from the threshold value for the "different positions" depending on the movement speed of the processing unit 2. In this case, the X-direction position of the roller 6 when it contacts the second edge surface Gb2 of the glass sheet G is determined in the same manner as in the third example. Also, if the abnormality of the glass sheet G is detected in the abnormality detection process, the movement of the pair of processing units 2 in the X direction is stopped in the same manner as in the third example. After the stopping process is performed, the pair of processing units 2 are returned to their initial positions, and the misalignment of the glass sheet G is corrected. Then, the edge processing process is performed on the pair of first edge surfaces Ga1 of the glass sheet G.

[0075] In the above sixth example, a case has been described in which the glass plate G is inclined so that the first end face Ga1 moves upward in FIG. 11 as it moves in the X direction. However, this sixth example can also be applied in the same manner to a case in which the glass plate G is inclined so that the first end face Ga1 moves downward in FIG. 11 as it moves in the X direction.

[0076] FIG. 12 is a schematic plan view showing the implementation of a seventh example of the present manufacturing method. In this seventh example, an abnormality in the glass sheet G is detected when a pair of first end faces Ga1 and a pair of second end faces Gb2 of the glass sheet G are inclined. Therefore, the glass sheet G is misaligned and inclined, but the degree of inclination is greater than in the sixth example. Therefore, in the abnormality detection process, an abnormality in the glass sheet G is detected when one roller 6 contacts the second end face Gb2 of the glass sheet G and the other roller 6 contacts the first end face Ga1. Whether one roller 6 contacts the second end face Gb2 of the glass sheet G and the other roller 6 contacts the first end face Ga1 is determined by comparing the difference between the rate of change in the Y direction of one roller 6 and the rate of change in the Y direction of the other roller 6 when the rollers 6 move in the X direction. Specifically, in FIG. 12 , the angle α between a line extending from one roller 6 in the X direction and the first end face Ga1 is smaller than the angle β between a line extending from the other roller 6 in the X direction and the second end face Gb2. Therefore, the rate of change in the Y direction when one roller 6 moves in the X direction is small. In this case, the X-direction position of one roller 6 when it contacts the second end face Gb2 is determined in the same manner as in the third example. Furthermore, the X-direction position of the other roller 6 when it contacts the first end face Ga1 and is determined to be an abnormality is determined in the same manner as in the fourth example. Similarly to the sixth example, if the abnormality of the glass sheet G is detected in the abnormality detection step, the movement of the pair of processing units 2 in the X direction is stopped in the interruption step. Furthermore, after the interruption step is performed, the pair of processing units 2 are returned to their initial positions, and the misalignment of the glass sheet G is corrected. Then, the edge processing step is performed on the pair of first end faces Ga1 of the glass sheet G.

[0077] In the seventh example described above, the case where the glass plate G is inclined so that the first end face Ga1 moves upward in FIG. 12 as it moves in the X direction has been described. However, this seventh example can also be applied in the same manner to the case where the glass plate G is inclined so that the first end face Ga1 moves downward in FIG. 12 as it moves in the X direction.

[0078] The method for manufacturing a glass plate according to an embodiment of the present invention has been described above. However, the embodiment of the present invention is not limited to this, and various modifications are possible within the scope of the gist of the present invention.

[0079] For example, in the above embodiment, the glass sheet G was set in a fixed position, and the anomaly detection device 4 and the edge surface processing device 5 were moved in the X direction as the processing unit 2. However, the anomaly detection device 4 and the edge surface processing device 5 may be set in a fixed position (not necessarily as the processing unit 2) and the glass sheet G may be moved in the direction opposite to the X direction. In this case, it is preferable to move multiple glass sheets G continuously in sequence. As a moving method, it is preferable to clamp each glass sheet G between belts extending in the moving direction from both the front and back sides so that the entire first edge surface Ga1 and a portion of the second edge surface Gb2 of each glass sheet G are exposed, and transport each glass sheet G by the belts. In this case, the transport speed of each glass sheet G can be increased, which may cause problems such as the rollers 6 of the anomaly detection device 4 colliding with the second edge surface Gb2 of the glass sheet G and damaging the anomaly detection device 4. Therefore, in this case, the arm member 7 of the abnormality detection device 4 is kept in an inclined state, and the roller 6 is configured to contact the corner Gc and then the first end face Ga1 without contacting the second end face Gb2. Even in this case, the roller 6 may be brought into contact with the second end face Gb2 if the conveying speed at which each glass sheet G approaches the abnormality detection device 4 is approximately the same as the speed at which the glass sheet G is set in a fixed position and the abnormality detection device 4 and the edge face processing device 5 are moved.

[0080] In the above embodiment, two edge processing devices 5 are arranged corresponding to one first edge face Ga1 of the glass sheet G, but the number of the edge processing devices 5 may be one or three or more. When there are three or more edge processing devices 5, the pressing force (contact pressure) from all the grinding wheels 12 of the edge processing devices 5 to the first edge face Ga1 is greater than the pressing force (contact pressure) from the roller 6 to the first edge face Ga1.

[0081] In the first and second examples of the manufacturing method in the above embodiment, the abnormality detection device 4 and the edge surface processing device 5 are arranged corresponding to a pair of first end surfaces Ga1 of the glass plate G, respectively, but the abnormality detection device 4 and the edge surface processing device 5 may also be arranged corresponding to only one of the first end surfaces Ga1.

[0082] DESCRIPTION OF SYMBOLS 1 Glass plate manufacturing device 2 Processing unit 3 Moving base 4 Abnormality detection device 5 Edge surface processing device 6 Roller (contactor) 7 Arm member 9 Servo motor 12 Grinding stone (processing tool) G Glass plate Ga First side of glass plate Ga1 First end surface of glass plate (end surface of first side) Gb Second side of glass plate Gb1 Other end surface of second side of glass plate Gb2 Second end surface of glass plate (one end surface of second side of glass plate) Gx Concave portion (abnormality occurring on first end surface of glass plate) Gy Convex portion (abnormality occurring on first end surface of glass plate) α Angle of arm member

Claims

1. A method for manufacturing a glass plate, comprising an edge processing step of moving a processing tool relative to a glass plate and bringing the processing tool into contact with an edge surface of a first side of the glass plate extending in the direction of the relative movement to process the edge surface, the method comprising: an abnormality detection step of detecting an abnormality in the glass plate by bringing a contactor of an abnormality detection device, which moves relative to the glass plate together with the processing tool and is configured to contact the edge surface of the first side of the glass plate before the processing tool does, into contact with at least one of the edge surfaces of the first side and the edge surface of a second side perpendicular to the end surface of the first side of the glass plate; and an interruption step of interrupting the edge processing step when an abnormality in the glass plate is detected in the abnormality detection step.

2. The method for manufacturing a glass plate as described in claim 1, characterized in that the abnormality in the glass plate is a convex or concave portion that occurs partially on the end face of a first side of the glass plate, the abnormality detection process is carried out during the end face processing process, and in the abnormality detection process, the glass plate is deemed to be abnormal when the contactor climbs onto the convex portion or enters into the concave portion.

3. The method for manufacturing a glass plate as described in claim 2, characterized in that, in the stopping step, the processing tool is withdrawn to a position where it does not interfere with the glass plate, and, after the stopping step is performed, the glass plate is discarded or reused by removing the convex portion or the concave portion.

4. A method for manufacturing a glass plate as described in any one of claims 1 to 3, characterized in that the contactor exerts a smaller contact pressure on the end face of the first side of the glass plate than the processing tool.

5. A method for manufacturing a glass plate as described in any one of claims 1 to 3, characterized in that the abnormality detection device is provided with a swingable arm member, the contactor is attached to the tip of the arm member and is biased toward the end face of the first side of the glass plate, the glass plate is set in a fixed position, and the processing tool and the arm member are held by a single movable base and move together as a unit.

6. The method for manufacturing a glass plate as described in claim 1, characterized in that the edge processing step is performed by contacting a pair of the processing tools with the edge faces of a pair of first sides of the glass plate, and the abnormality detection step is performed before the edge processing step is performed.

7. A method for manufacturing a glass plate as described in claim 6, characterized in that the abnormality in the glass plate is an abnormality in the position of the glass plate in a direction along a first side, and in the abnormality detection process, a case in which a pair of contacts contact an end face of one of the second sides of the glass plate at the same position in the direction along the first side and the position is different from a normal position is determined to be an abnormality in the glass plate.

8. The method for manufacturing a glass plate as described in claim 7, characterized in that in the interruption process, the relative movement between the pair of processing tools and the glass plate is interrupted, and after the interruption process is performed, the positional abnormality is corrected and the edge processing process is performed on the glass plate.

9. A method for manufacturing a glass plate as described in claim 6, characterized in that the abnormality in the glass plate is an abnormality in the position of the glass plate in the direction along the second side, and in the abnormality detection process, when the pair of contactors are in contact with the end faces of a pair of first sides of the glass plate, the glass plate is deemed to be abnormal if any of the positions of the pair of contactors in the direction along the second side of the glass plate differs from a normal position and the distance between the pair of contactors is the same as the normal distance.

10. A method for manufacturing a glass plate as described in claim 9, characterized in that in the interruption process, the pair of processing tools are retreated to a position where they do not interfere with the glass plate, and after the interruption process is performed, the positional abnormality is corrected and the edge processing process is performed on the glass plate.

11. A method for manufacturing a glass plate as described in claim 6, characterized in that the abnormality in the glass plate is a deviation in the dimension of the glass plate in the direction along the second side, and in the abnormality detection process, a case in which the distance between the pair of contacts is different from the normal distance when the pair of contacts are in contact with the end faces of a pair of first sides of the glass plate is determined to be abnormal.

12. A method for manufacturing a glass plate as described in claim 11, characterized in that, in the interruption process, the pair of processing tools are retracted to a position where they do not interfere with the glass plate, and after the interruption process is performed, the glass plate is discarded or the size of the glass plate is adjusted and reused.

13. A method for manufacturing a glass plate as described in claim 6, characterized in that the abnormality in the glass plate is a misalignment in which the glass plate is in an inclined position, and in the abnormality detection process, an abnormality in the glass plate is detected when one contactor and the other contactor of the pair of contactors contact an end face of a second side of the glass plate at different positions in a direction along the first side, or when one contactor contacts an end face of the second side of the glass plate and the other contactor contacts an end face of the first side of the glass plate.

14. A method for manufacturing a glass plate as described in claim 13, characterized in that in the interruption process, the relative movement between the pair of processing tools and the glass plate is interrupted, and after the interruption process is performed, the misalignment is corrected and the edge processing process is performed on the glass plate.

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