Glass plate manufacturing method and manufacturing device

Abstract

To smoothly switch the step from a first cutting step to a second cutting step.SOLUTION: A method for manufacturing a glass sheet includes: a first cutting step of cutting a glass sheet out by a first cutting device 2 from a glass ribbon G that is transported while being shaped; a second cutting step of cutting a glass ribbon G by a second cutting device 3 when the first cutting device 2 is not operated; a first detection step of detecting if a glass ribbon G is present or not with a first sensor 30; and a switching step of switching the first cutting step to the second cutting step on the basis of a detection result in the first detection step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for manufacturing glass sheets, and more particularly to a technology for performing a first cut to cut a glass sheet by cutting a glass ribbon that is being shaped and transported, and a second cut to cut the glass ribbon when the first cut is not performed. [Background technology]

[0002] In the field of glass sheet manufacturing, it is known to perform a first cutting step in which a glass ribbon that is being formed in a forming zone and continuously moving downward is cut in the width direction at predetermined lengths to sequentially cut out glass sheets. In this case, since the melting furnace or the like of the glass sheet manufacturing facility is usually operated continuously, even if the device for performing the first cutting step is unavailable due to maintenance or the like, the glass ribbon generally continues to be formed. Therefore, even if the first cutting step is not performed, it is necessary to cut and recover the glass ribbon that continues to be formed.

[0003] In order to meet such demands, for example, Patent Document 1 discloses that when the first cutting step is not performed, a second cutting step is performed in which the glass ribbon is cut using an apparatus having a configuration different from that of the apparatus used in the first cutting step. The apparatus used in this second cutting step includes a holding member that holds the glass ribbon, a pressing member that applies stress to the glass ribbon while the glass ribbon is held by the holding member, and a scribing member that carves a scribing line in the stress-applied portion of the glass ribbon. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] China Utility Model Publication No. 205493369 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described method for manufacturing a glass sheet, for example, if a cutting defect or the like occurs when cutting the glass ribbon in the first cutting step, a crack may extend in the conveying direction, causing the glass ribbon to break. Furthermore, the glass ribbon may be scratched by rollers conveying the glass ribbon, causing the glass ribbon to break. Among these types of breakage, there is a type in which the glass ribbon being shaped and conveyed is completely broken and disappears. When the glass ribbon is broken, the first cutting step is interrupted, and the second cutting step is made ready to start. When the shaping of the glass ribbon is resumed after the glass ribbon is broken, the second cutting step is started. Conventionally, such a switch from the first cutting step to the second cutting step has been performed by an operator. Therefore, it has been difficult to perform a smooth switchover.

[0006] In view of the above, an object of the present invention is to smoothly switch from the first cutting step to the second cutting step. [Means for solving the problem]

[0007] A first aspect of the present invention, which has been devised to solve the above-mentioned problems, is a method for manufacturing a glass plate, comprising: a first cutting step in which a glass ribbon being formed and transported is cut by a first cutting device to cut out a glass plate; and a second cutting step in which the glass ribbon is cut by a second cutting device when the first cutting device is not operating, characterized in that the method comprises a first detection step in which the presence or absence of a glass ribbon is detected by a sensor, and a switching step in which the first cutting step is switched to the second cutting step based on the detection result in the first detection step.

[0008] According to this configuration, the switching step for switching from the first cutting step to the second cutting step is performed based on the detection result of the sensor that detects the presence or absence of the glass ribbon, and therefore the switching can be performed smoothly. Furthermore, by detecting the presence or absence of the glass ribbon by the sensor, it is possible to accurately know, for example, when the forming of the glass ribbon is resumed, and it is possible to start the second cutting step at an appropriate time.

[0009] In this configuration, the sensors may be installed at a plurality of locations in the width direction of the glass ribbon.

[0010] In this way, the presence or absence of the glass ribbon can be detected at multiple locations across the width using multiple sensors, allowing for precise understanding of the shape of the glass ribbon at the time of breakage and the forming state of the glass ribbon when forming resumes after breakage.

[0011] In the above configuration, the sensors are installed corresponding to at least both widthwise ends and a widthwise middle portion of the glass ribbon, and the detection results in the first detection process may make it possible to distinguish between a first state in which one of the widthwise end ends of the glass ribbon is being shaped while being transported, a second state in which one of the widthwise end ends of the glass ribbon and the widthwise middle portion are being shaped while being transported, a third state in which both widthwise end ends of the glass ribbon are being shaped while being transported, and a fourth state in which the entire widthwise portion of the glass ribbon is being shaped while being transported.

[0012] In this way, the glass ribbon forming process and conveying process when forming is resumed after breakage can be distinguished and understood according to the four states listed above, and the switching process and second cutting process can be appropriately performed in accordance with the four states.

[0013] In the above configuration, in the first detection step, the sensor may detect the presence or absence of the glass ribbon upstream of the first cutting device and the second cutting device in the conveying direction.

[0014] In this way, it is possible to take appropriate measures for the first cutting device and the second cutting device after confirming with the sensor that glass fragments or the like will fall due to breakage. In addition, it is possible to appropriately carry out the switching step and the second cutting step after confirming the formed state of the glass ribbon when forming is resumed after breakage.

[0015] In this configuration, the switching step may include causing a component of the second cutting device to advance from the evacuation area to the cutting area based on the detection result of the first detection step.

[0016] Here, the above-mentioned "cutting area" refers to an area where the second cutting device performs cutting processing of the glass ribbon. Also, the above-mentioned "retreat area" refers to an area where the second cutting device retreats from the cutting area (for example, an area 500 mm to 2000 mm away from the conveying path of the glass ribbon). Furthermore, the above-mentioned "components of the second cutting device" may refer to all or some of the components of the second cutting device.

[0017] In this way, after the glass ribbon breaks, it is possible to advance the components of the second cutting device from the evacuation area to the cutting area after confirming that glass fragments and the like have stopped falling into the cutting area. This makes it possible to avoid problems such as glass fragments and the like colliding with the components of the second cutting device when the second cutting device starts cutting the glass ribbon. Therefore, it is preferable that the evacuation area is an area where the above-mentioned glass fragments and the like do not fall. Furthermore, with this configuration, it is possible to appropriately advance the components of the second cutting device after confirming the forming state of the glass ribbon when forming is resumed after breakage.

[0018] In this configuration, the component of the second cutting device may be a part of all the components of the second cutting device and may be the component that advances earliest among all the components when the cutting process by the second cutting device is started.

[0019] In this way, by protecting the component that advances earliest from falling glass fragments, etc., it is possible to reliably protect other components that advance later. Furthermore, with this configuration, it is possible to appropriately operate the component that advances earliest after checking the forming state of the glass ribbon when forming is resumed after breakage, etc.

[0020] In this configuration, the sensors are installed corresponding to at least both widthwise end portions of the glass ribbon, and the component that advances earliest is one or both of holding members used to hold both widthwise end portions of the glass ribbon when cutting in the second cutting step, and the glass ribbon that is detected to be one of the holding members by the sensors Width The holding members corresponding to the width direction ends may be advanced, and the holding members corresponding to the width direction ends of the glass ribbon whose absence is detected by the sensor may not be advanced.

[0021] In this manner, sensors are installed corresponding to at least both widthwise ends of the glass ribbon, respectively. Therefore, one sensor detects the presence or absence of one widthwise end of the glass ribbon, and the other sensor detects the presence or absence of the other widthwise end of the glass ribbon. Furthermore, at the location corresponding to the widthwise end of the glass ribbon where the presence is detected, glass fragments or the like do not fall due to breakage, and therefore, even if the holding member corresponding to the widthwise end is advanced, problems such as glass fragments or the like colliding with the holding member do not occur. On the other hand, at the location corresponding to the widthwise end of the glass ribbon where the absence is detected, glass fragments or the like do fall due to breakage. Therefore, by not advancing the holding member corresponding to the widthwise end, problems such as glass fragments or the like colliding with the holding member can be avoided. Furthermore, according to this configuration, the widthwise end of the glass ribbon where the presence is detected is continuously shaped and conveyed, so the widthwise end needs to be cut. Therefore, by advancing the holding member corresponding to the widthwise end, the widthwise end can be cut to an appropriate length. On the other hand, the width-wise end of the glass ribbon that is detected as being absent can be left as is until it is subsequently detected that it has been formed, so there is no need to advance the holding member corresponding to that width-wise end.

[0022] In the above-described configuration, a second detection process may be further provided in which sensors are installed corresponding to at least both widthwise ends of the glass ribbon at positions downstream in the conveying direction from the sensors used in the first detection process to detect the presence or absence of the glass ribbon, and based on the detection results of these sensors, cutting processing of the glass ribbon is performed using components of the second cutting device advanced in the switching process.

[0023] In this way, the cutting process of the glass ribbon using the components of the second cutting device (including the above-mentioned holding member) is carried out accurately by incorporating the detection results from the second detection process in addition to the detection results from the first detection process described above.

[0024] In this configuration, the components of the second cutting device may include a cutting blade used to cut the glass ribbon, and the cutting blade may be pressed against the glass ribbon based on the detection results in the second detection process.

[0025] In this way, the cutting process of the glass ribbon can be performed more accurately using the cutting blade and the above-mentioned holding member, etc.

[0026] In this configuration, the components of the second cutting device may include a pressing member that applies stress to the glass ribbon, and the pressing member may be configured to apply stress to the glass ribbon based on the detection results in the second detection process.

[0027] In this way, the cutting process of the glass ribbon can be performed even more accurately using the cutting blade, the pressing member, the above-mentioned holding member, etc.

[0028] A second aspect of the present invention, which was invented to solve the above-mentioned problems, is a glass plate manufacturing apparatus comprising: a first cutting device that cuts a glass ribbon that is being formed and transported to cut out a glass plate; and a second cutting device that cuts the glass ribbon when the first cutting device is not operating, characterized in that the apparatus is provided with a sensor that detects the presence or absence of a glass ribbon, and is configured to perform a switching process to switch operation of the first cutting device to operation of the second cutting device based on the detection result of the sensor.

[0029] This makes it possible to obtain the same effects as those of the previously described manufacturing method, which has substantially the same configuration as this manufacturing apparatus. [Effects of the Invention]

[0030] According to the present invention, the first cutting step can be smoothly switched to the second cutting step. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a side view showing an overall configuration of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 2] 1 is a schematic front view showing a main part of a glass sheet manufacturing apparatus according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic side view illustrating the operation of a first cutting device in the glass plate manufacturing apparatus according to the embodiment of the present invention. [Figure 4] FIG. 3 is an enlarged schematic plan view showing a second cutting device in the glass plate manufacturing apparatus according to the embodiment of the present invention. [Figure 5] FIG. 3 is an enlarged schematic plan view showing a second cutting device in the glass plate manufacturing apparatus according to the embodiment of the present invention. [Figure 6] FIG. 3 is an enlarged side view showing a second cutting device in the glass plate manufacturing apparatus according to the embodiment of the present invention. [Figure 7] FIG. 4 is an enlarged schematic side view showing the operation of a second cutting device in the glass plate manufacturing apparatus according to the embodiment of the present invention. [Figure 8]FIG. 2 is a schematic front view of a main part illustrating an aspect when a glass ribbon is cut using a second cutting device in the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 9] FIG. 2 is a schematic front view of a main part illustrating an aspect when a glass ribbon is cut using a second cutting device in the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 10] 10(a), (b), and (c) are schematic front views each showing an aspect of cutting a glass ribbon using the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 11] 11(a), (b), and (c) are schematic front views each showing an aspect of cutting a glass ribbon using the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 12] 12(a) and 12(b) are each a schematic front view showing an aspect of cutting a glass ribbon using the glass sheet manufacturing apparatus according to the embodiment of the present invention. [Figure 13] 13(a) and 13(b) are each a schematic front view showing an aspect of cutting a glass ribbon using the glass sheet manufacturing apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0033] FIG. 1 is a side view showing the overall configuration of a glass sheet manufacturing apparatus according to this embodiment. As shown in the figure, the glass sheet manufacturing apparatus includes, as main components, a glass ribbon G processing device 1, a first cutting device 2, and a second cutting device 3. In the following description, the second main surface Gb side of the glass ribbon G (the side indicated by the arrow X1 in FIG. 1) is referred to as the "front side," and the first main surface Ga side (the side indicated by the arrow Y1 in FIG. 1) is referred to as the "rear side." In addition, in this embodiment, the downstream side of the conveyance direction of the glass ribbon G is referred to as the "downward side (preferably vertically downward)," and the upstream side is referred to as the "upward side (preferably vertically upward)."

[0034] The processing device 1 includes a forming zone 11 for continuously forming a glass ribbon G, a heat treatment zone 12 for heat treating (slowly cooling) the glass ribbon G, a cooling zone 13 for cooling the glass ribbon G to near room temperature, and a conveying device 14 consisting of roller pairs R arranged in multiple vertical stages in each of the forming zone 11, the heat treatment zone 12, and the cooling zone 13.

[0035] The forming zone 11 and the heat treatment zone 12 are constituted by furnaces in which the transport path of the glass ribbon G is surrounded by walls, and heating devices such as heaters that adjust the temperature of the glass ribbon G are disposed at appropriate locations within the furnaces. On the other hand, the cooling zone 13 is open to the external atmosphere at room temperature without the transport path of the glass ribbon G being surrounded by walls, and no heating device such as a heater is disposed therein.

[0036] A forming body 15 is disposed in the internal space of the forming zone 11, and forms a glass ribbon G from molten glass Gm by the overflow downdraw method. The molten glass Gm supplied to the forming body 15 overflows from a groove (not shown) formed in the top 15a of the forming body 15. The overflowing molten glass Gm flows down both side surfaces 15b, which have a wedge-shaped cross section, of the forming body 15 and joins at the lower end. In this way, a plate-shaped glass ribbon G is continuously formed. The continuously formed glass ribbon G is sent downward in a vertical position (preferably a vertical position).

[0037] The internal space of the heat treatment zone 12 has a predetermined temperature gradient downward. The glass ribbon G in the vertical position is heat-treated (slowly cooled) so that its temperature decreases as it moves downward through the internal space of the heat treatment zone 12. This heat treatment reduces internal strain in the glass ribbon G. The temperature gradient in the internal space of the heat treatment zone 12 is adjusted, for example, by a heating device provided on the inner wall surface of the heat treatment zone 12.

[0038] The plurality of roller pairs R constituting the conveying device 14 clamp both widthwise ends of the glass ribbon G in a vertical position from both the front and back sides. The uppermost roller pair R arranged in the forming zone 11 is a cooling roller. Note that, in the internal space of the heat treatment zone 12, the plurality of roller pairs R may include ones that do not clamp the widthwise ends of the glass ribbon G. In other words, the distance between the opposing roller pairs R may be made larger than the thickness of both widthwise ends of the glass ribbon G, and the glass ribbon G may pass between the roller pairs R.

[0039] In this embodiment, both widthwise end portions of the glass ribbon G produced by the processing device 1 have portions (hereinafter also referred to as "ear portions") that are thicker than the widthwise central portion due to the influence of shrinkage during the molding process and the like.

[0040] The first cutting device 2 is configured to cut the glass ribbon G in a vertical position below the processing device 1 in the width direction at predetermined lengths, thereby sequentially cutting out glass plates from the glass ribbon G. The glass plates become raw glass plates (mother glass plates) from which one or more product glass plates are obtained in a later process by removing the edge portions. Here, the width direction is a direction perpendicular to the longitudinal direction (conveyance direction) of the glass ribbon G and substantially coincides with the horizontal direction in this embodiment. In the following description, when the glass ribbon G is viewed from the rear as shown in FIG. 2, the side indicated by the arrow X2 in the figure is the left side in the width direction, and the side indicated by the arrow Y2 in the figure is the right side in the width direction.

[0041] 1 and 2, the first cutting device 2 includes a bending and splitting device 22. This bending and splitting device 22 is a device that bends and splits the glass ribbon G along a scribe line S at a bending and splitting position P2 provided below the scribe line forming position P1 to cut out a glass sheet. In this embodiment, the bending and splitting device 22 includes a bending and splitting member 23 that abuts against the region where the scribe line S is formed from the second main surface Gb side, and a gripping mechanism 24 that grips a lower region of the glass ribbon G below the bending and splitting position P2.

[0042] The splitting member 23 is composed of a plate-like body (surface plate) having a contact surface (arc-shaped in side view) that comes into contact with the entire width or part of the width direction of the glass ribbon G. The contact surface of the splitting member 23 may be a curved surface that is curved in the width direction in a plan view.

[0043] The gripping mechanism 24 includes chucks 25 arranged at multiple locations in the vertical direction at both widthwise ends of the glass ribbon G, and arms 26 (see FIG. 2) that hold the multiple chucks 25 at both widthwise ends. Note that the chucks 25 may be changed to another holding form, such as holding the glass ribbon G by negative pressure suction.

[0044] A scribe line forming device 27 is provided above the first cutting device 2. This scribe line forming device 27 is a device that forms a scribe line S on the first main surface Ga of the glass ribbon G in a vertical position that has been lowered from the processing device 1 at a scribe line forming position P1. In this embodiment, the scribe line forming device 27 includes a wheel cutter 28 that forms a scribe line S on the first main surface Ga of the glass ribbon G along its width direction, and a support member 29 (e.g., a support bar or a support roller) that supports the second main surface Gb of the glass ribbon G (the surface opposite to the first main surface Ga) at a position corresponding to the wheel cutter 28. The scribe line S may also be formed by laser irradiation or the like.

[0045] As shown in FIG. 3 , the first cutting device 2 and the scribe line forming device 27 are configured to move between a cutting area E1 (hereinafter referred to as the first cutting area E1) including a conveyance path GS of the glass ribbon G and a retreat area F1 (hereinafter referred to as the first retreat area F1) spaced apart from the conveyance path GS of the glass ribbon G on both the front and rear sides. Here, the first retreat area F1 is spaced apart from the conveyance path GS of the glass ribbon G by a predetermined distance La on both the front and rear sides. This predetermined distance La is, for example, 200 to 1000 mm, and preferably 300 to 600 mm. In this embodiment, the first cutting device 2 is configured such that both the splitting member 23 and the gripping mechanism 24 move only from the first cutting area E1 to the forward first retreat area F1. Furthermore, the scribe line forming device 27 is configured such that the support member 29 moves from the first cutting area E1 to the forward first retreat area F1, and the wheel cutter 28 moves from the first cutting area E1 to the rear first retreat area F1.

[0046] Furthermore, a first sensor 30 that detects the presence (state) of the glass ribbon G is disposed at a fixed position above the first cutting device 2 (see FIGS. 1 and 2). In the illustrated example, the first sensor 30 is disposed behind the conveying path GS of the glass ribbon G, but it may also be disposed in front of the conveying path GS. In addition, the first sensor 30 is disposed above the scribe line forming device 27, but it may also be disposed between the first cutting device 2 and the scribe line forming device 27.

[0047] In this case, as shown in Fig. 2, a plurality of first sensors 30 are installed corresponding to a plurality of positions in the width direction of the glass ribbon G. In this embodiment, a total of three first sensors 30 are installed at positions corresponding to both ends in the width direction of the glass ribbon G and at a position corresponding to the center in the width direction. These first sensors 30 are fixed to an installation member not shown in the figure so as to be aligned in a straight line in the width direction. As the first sensors 30, a laser sensor, an ultrasonic sensor, a thermosensor, or the like is used. The first sensors 30 constantly detect the presence or absence of the glass ribbon G.

[0048] As shown in Figures 1 and 2, the second cutting device 3 is arranged below the first cutting device 2, and cuts the glass ribbon G being formed in the forming zone 11 and transported downward when the first cutting device 2 is not in operation (for example, during maintenance or when forming of the glass ribbon G is resumed).

[0049] The second cutting device 3 includes a main body frame 31 consisting of a framework disposed behind the glass ribbon G. A pair of holding devices 32, a pair of cutting devices 33, and a stress applying device 34 are attached to the front end of the main body frame 31 in this order from above.

[0050] The pair of holding devices 32 include holding members 36 arranged corresponding to both widthwise ends of the glass ribbon G, and each of the pair of holding members 36 is rotatable around a rotation shaft 37 (see FIGS. 4 and 5). Therefore, each of the pair of holding members 36 is changeable between a state in which it extends in the front-rear direction away from both widthwise ends of the glass ribbon G as shown in FIG. 4 (a state shown by a solid line in FIG. 6), and a state in which it extends in the left-right direction to hold the second main surface Gb of the glass ribbon G as shown in FIG. 5 (a state shown by a dashed dotted line in FIG. 6).

[0051] Furthermore, as shown in FIG. 6, each of the pair of holding members 36 is connected to the front end of a slide arm 36a that is long in the front-rear direction via a rotation shaft 37. The pair of slide arms 36a are held slidably in the front-rear direction on guide members 36b, each fixed to the upper end of the main body frame 31. As shown in FIG. 7, each of the pair of holding members 36 is configured to move between a cutting area E2 (hereinafter referred to as the second cutting area E2) that includes a conveying path GS of the glass ribbon G and an evacuation area F2 (hereinafter referred to as the second evacuation area F2) that is spaced rearward from the conveying path GS of the glass ribbon G. Here, the second evacuation area F2 is spaced rearward from the conveying path GS of the glass ribbon G by a predetermined distance Lb. This predetermined distance Lb is, for example, 500 to 2000 mm, preferably 700 to 1500 mm, and is longer than the above-mentioned predetermined distance La. These holding members 36 are held at the same height position and can each move independently. In this case, the advancement of each holding member 36 from the second evacuation area F2 to the second cutting area E2 is performed based on the detection result of the first sensor 30. The evacuation of each holding member 36 from the second cutting area E2 to the second evacuation area F2 is also performed based on the detection result of the first sensor 30. In this embodiment, the movement of each holding member 36 (each slide arm) in the front-rear direction is performed by the operation of a driving means (e.g., an air cylinder or a ball screw mechanism) not shown, and the operation of the driving means is controlled based on a signal from the first sensor 30.

[0052] The pair of cutting devices 33 includes rotary blades 38 disposed corresponding to both widthwise ends of the glass ribbon G, and each of the pair of rotary blades 38 is movable in the front-rear direction (a direction inclined upward toward the front) (see FIGS. 2 and 6 ). Furthermore, each of the pair of rotary blades 38 is changeable between a state in which it is retracted rearward from the glass ribbon G as shown in FIG. 4 (a state shown by a solid line in FIG. 6 ) and a state in which it presses both widthwise ends of the glass ribbon G as shown in FIG. 5 (a state shown by a dashed line in FIG. 6 ). Each of the pair of rotary blades 38 is also movable left-right. The pair of rotary blades 38 are held at the same height position and can move and operate independently. When each rotary blade 38 is pressed against the glass ribbon G, it is possible to perform a process of inscribing a scribe line on the widthwise end of the glass ribbon G and a process of cutting the widthwise end of the glass ribbon G.

[0053] The stress applying device 34 has pressing members 41 attached to the tips of a pair of swinging arms 40 that can swing around a support shaft 39 (see FIGS. 2 and 6). The pressing members 41 are roller-shaped members that extend in the width direction and are longer than the width direction length of the glass ribbon G. Furthermore, the pressing members 41 are changeable between a state in which they are retracted rearward from the glass ribbon G as shown in FIG. 4 (a state shown by a solid line in FIG. 6) and a state in which they press the glass ribbon G as shown in FIG. 5 (a state shown by a dashed-dotted line in FIG. 6). When the pressing members 41 are pressing the glass ribbon G, bending stress is applied to the glass ribbon G (details will be described later).

[0054] Furthermore, as shown in FIG. 6 , the second cutting device 3 is equipped with a second sensor 35 that detects the presence or absence of the glass ribbon G. In the illustrated example, the second sensor 35 is fixed to the main body frame 31 and thereby disposed rearward of the conveyance path of the glass ribbon G. The second sensor 35 is also disposed at a height intermediate between the support shaft 39 at the upper end of the stress applying device 34 and the pressing member 41 at the lower end. In this case, as shown in FIG. 2 , a plurality of second sensors 35 are installed corresponding to a plurality of positions in the width direction of the glass ribbon G. In this embodiment, a total of three second sensors 35 are installed at positions corresponding to both widthwise ends of the glass ribbon G and a position corresponding to the widthwise center. These second sensors 35 are fixed to the front end of the main body frame 31 so as to be aligned in a straight line in the width direction and are held at a fixed position. A laser sensor, an ultrasonic sensor, a thermosensor, or the like is used as the second sensor 35. The second sensor 35 constantly detects the presence or absence of the glass ribbon G.

[0055] This manufacturing apparatus is configured to perform a switching process for switching the operation of the first cutting device 2 to the operation of the second cutting device 3. In the present embodiment, the switching process corresponds to advancing the holding members 36, which are extended in the front-rear direction, from the second evacuation area F2 to the second cutting area E2. After the switching process is performed, the second cutting device 3 performs a cutting process on the glass ribbon G while the holding members 36 remain in the second cutting area E2.

[0056] Here, the basic cutting process (hereinafter referred to as the first process) performed by the second cutting device 3 will be described. When performing the first process, first, while the glass ribbon G is continuously conveyed downward as shown by the solid line in FIG. 6 , the pair of holding members 36 rotate around the rotation shaft 37 from a state in which they extend in the front-rear direction. As a result, the pair of holding members 36 extend in the left-right direction as shown by the dashed-dotted line in the same figure, enabling them to hold the second main surface Gb of the glass ribbon G. Next, under this state, the pressing member 41 swings forward. As a result, the pressing member 41 presses the glass ribbon G as shown by the dashed-dotted line in the same figure, applying bending stress to the periphery of the region Gx of the glass ribbon G to be cut. At this time, the pair of holding members 36 hold the second main surface Gb of the glass ribbon G above the region Gx to be cut, preventing the glass ribbon G from displacing forward. Furthermore, under this state, the pair of rotary blades 38 move forward. As a result, the pair of rotary blades 38 press against the first main surface Ga of the glass ribbon G as indicated by the dashed dotted line in the figure, and carve a scribe line (initial crack) into the glass ribbon G. The pair of rotary blades 38 simultaneously carve the initial crack at both widthwise ends of the glass ribbon G. Note that, when sufficient bending stress is applied to the periphery of the region Gx of the glass ribbon G to be cut over the entire widthwise length, one of the rotary blades 38 may carve the initial crack only at one widthwise end of the glass ribbon G. The carved position of the initial crack may be a position that includes or does not include the edge portion of the glass ribbon G. The initial crack then propagates along the widthwise direction of the glass ribbon G, thereby cutting the glass ribbon G. The cut glass becomes unwanted glass Gy and falls downward, and is collected in the collection area 42. Thereafter, the holding member 36 returns to its extended state in the front-rear direction, ready for the subsequent cutting process. An opening 44 is formed in the floor wall 43 on which the second cutting device 3 is mounted to allow the cut glass to fall into the recovery area 42.

[0057] This first process is repeatedly performed while the second cutting device 3 is operating with no breakage in the glass ribbon G. When the second cutting device 3 is not operating, the holding members 36 are retracted to the second retraction area F2 while extending in the front-rear direction.

[0058] In addition to the first process described above, the second cutting device 3 can also perform the second process described below as a cutting process. The second process is a cutting process that is performed, for example, when only one widthwise end of the glass ribbon G is formed when forming is resumed after breakage. When performing the second process, first, as shown in FIG. 8 , when only one widthwise end (the left end in the illustrated example) G1 of the glass ribbon G is transported to the second cutting area E2, only the holding member 36 corresponding to the widthwise end G1 rotates from a state in which it extends in the front-rear direction to a state in which it extends in the left-right direction. At this time, the holding member 36 corresponding to the other widthwise end (the right end in the illustrated example) of the glass ribbon G does not operate. Next, the rotary blade 38 corresponding to the widthwise end G1 of the glass ribbon G presses the widthwise end G1 against the glass ribbon G and moves left-right. As a result, the widthwise end G1 is cut along the line (straight line) indicated by the symbol L1 in the figure. At this time, the rotary blade 38 corresponding to the other widthwise end (the right end in the illustrated example) of the glass ribbon G does not operate. Although the drawing illustrates an example of the cutting operation of only the right end G1 of the glass ribbon G in the width direction, it is also possible to similarly cut only the left end of the glass ribbon G in the width direction. When performing this second process, an operation of applying bending stress to the glass ribbon G by the pressing member 41 is not performed.

[0059] Furthermore, in addition to the first and second processes described above, the second cutting device 3 can also perform the third process described below as a cutting process. The third process is a cutting process performed, for example, when forming of the glass ribbon G is resumed after breakage, and only both widthwise ends are formed without forming the central portion of the glass ribbon G. When performing the third process, first, as shown in FIG. 9 , when only both widthwise ends G1 and G2 of the glass ribbon G are transported to the second cutting area E2, the pair of holding members 36 rotate from a state in which they extend in the front-rear direction to a state in which they extend in the left-right direction. Next, the pair of rotary blades 38 press both widthwise ends G1 and G2, respectively, and move left-right. As a result, both widthwise ends G1 and G2 are cut along the lines (straight lines) indicated by the symbols L1 and L2 in the figure. When performing the third process, the pressing member 41 does not apply bending stress to the glass ribbon G.

[0060] In this embodiment, the rotation of each holding member 36 is performed based on the detection result of the second sensor 35. More specifically, the rotation of each holding member 36 is performed by the operation of a drive means (e.g., a motor) not shown, and the operation of this drive means is controlled based on a signal from the second sensor 35. Furthermore, the forward / backward and left / right movement of each rotary blade 38 is also performed based on the detection result of the second sensor 35. More specifically, the forward / backward and left / right movement of each rotary blade 38 is performed by the operation of a drive means (e.g., an air cylinder or a ball screw mechanism) not shown, and the operation of this drive means is controlled based on a signal from the second sensor 35. Furthermore, the movement of the pressing member 41 is also performed based on the detection result of the second sensor 35. More specifically, the movement of the pressing member 41 is performed by the operation of a drive means (e.g., a motor) not shown, and the operation of this drive means is also controlled based on a signal from the second sensor 35.

[0061] Next, a method for manufacturing a glass sheet using the glass sheet manufacturing apparatus having the above-described configuration will be described.

[0062] The method for manufacturing a glass plate according to this embodiment includes a forming step, a transporting step, a first cutting step, a first detecting step, a second cutting step, a second detecting step, and a switching step.

[0063] The forming step is a step of forming a glass ribbon G in the forming zone 11 .

[0064] The conveying step is a step of conveying the formed glass ribbon G by the roller pair R of the conveying device 14. The conveying step includes a heat treatment step and a cooling step.

[0065] The heat treatment step is a step of carrying out a heat treatment on the glass ribbon G that has been subjected to the forming step while transporting the glass ribbon G in the heat treatment zone 12.

[0066] The cooling step is a step in which the glass ribbon G that has been subjected to the heat treatment step is cooled while being transported in the cooling zone 13.

[0067] The first cutting step is a step in which the glass ribbon G that has been subjected to the cooling step is conveyed and cut in the width direction by the first cutting device 2 to obtain glass plates.

[0068] More specifically, as shown in FIGS. 1 and 2 , in the first cutting step, first, a wheel cutter 28 and a support member 29 move following the glass ribbon G that is continuously moving downward, and form a scribe line S across the entire width or a portion of the width of the glass ribbon G. In the present embodiment, the scribe line S is also formed on the edge portions, which have a relatively large thickness. Next, after the plurality of chucks 25 grip the glass ribbon G, the arm 26 moves the plurality of chucks 25 following the glass ribbon G. At this time, the bending / splitting member 23 also moves following the glass ribbon G. While these movements are being performed, the arm 26 performs an operation (operation in the direction B shown in FIG. 1 ) to bend the glass ribbon G with the bending / splitting member 23 as a fulcrum. This imparts bending stress to the scribe line S and its vicinity, and the glass ribbon G is bent and split in the width direction along the scribe line S. As a result of this cutting by bending, a glass plate is cut out from the glass ribbon G.

[0069] The first detection step is a step of detecting the presence or absence of the glass ribbon G by the three first sensors 30, respectively.

[0070] The second cutting step is a step of cutting the glass ribbon G using the second cutting device 3 while the first cutting device 2 is not in operation.

[0071] The second detection step is a step of detecting the presence or absence of the glass ribbon G by the three second sensors 35, respectively.

[0072] The switching step is a step for switching from the first cutting step to the second cutting step based on the detection result of the first detection step, and is performed between the interruption of the first cutting step and the start of the second cutting step.

[0073] More specifically, while the first cutting step is being performed, that is, while the first cutting device 2 is operating, the holding member 36, the rotary blade 38, and the pressing member 41, which are components of the second cutting device 3, remain in the second retraction area F2 shown in Fig. 7. On the other hand, while the second cutting step is being performed, that is, while the second cutting device 3 is operating, the holding member 36 remains in the second cutting area E2 shown in Fig. 7.

[0074] When the first detection step detects that the glass ribbon G is absent due to breakage during the first cutting step, the first cutting device 2 retreats from the first cutting area E1 to the first evacuation area F1. Then, a switching step is performed based on the detection result of the subsequent first detection step. Specifically, in the switching step, the holding member 36, which is extended in the front-rear direction, is advanced from the second evacuation area F2 to the second cutting area E2. Then, after this switching step, the second cutting step is performed. Therefore, the first cutting step is interrupted due to breakage, and then the holding member 36 advances, and then the second cutting step is performed. In this embodiment, the switching step is smoothly performed by automation, with reduced or no operator intervention required.

[0075] If the glass ribbon G is broken, glass fragments and the like fall into the second cutting area E2, but the holding member 36 remains in the second evacuation area F2. The rotary blade 38 and the pressing member 41 also remain in the second evacuation area F2. The holding member 36 advances from the second evacuation area F2 to the second cutting area E2 earlier than the rotary blade 38 and the pressing member 41. In other words, among the components of the second cutting device 3, the holding member 36 advances from the second evacuation area F2 to the second cutting area E2 earlier than the rotary blade 38 and the pressing member 41.

[0076] Next, the process from when the glass ribbon G is broken during the first cutting step to when the glass ribbon G is cut in the second cutting step will be described with reference to Figs. 10 to 13. In these figures, the three circles arranged at an upper position of the first cutting device 2 represent the detection areas 30a of the three first sensors 30, and the three circles arranged at an intermediate position in the vertical direction of the second cutting device 3 represent the detection areas 35a of the three second sensors 35. In the following description, the case where the first and second sensors 30, 35 detect the presence of the glass ribbon G will be described as "ON," and the case where the absence of the glass ribbon G is detected will be described as "OFF."

[0077] FIG. 10 illustrates a first example of the above process. This first example illustrates a process in which, as shown in FIG. 10, forming is resumed after the glass ribbon G breaks during the first cutting step, so that both widthwise ends and the widthwise center of the glass ribbon G are shaped and conveyed. In this case, as the glass ribbon G is shaped and conveyed, the three first sensors 30 switch from the OFF state shown in FIG. 10(a) to the ON state shown in FIG. 10(b). After this switching, when a predetermined short time (e.g., 0.3 to 0.8 seconds, preferably 0.5 seconds) has elapsed, the pair of holding members 36 are advanced into the second cutting area E2. Here, the predetermined short time is the time required to confirm that the glass ribbon G being shaped and conveyed continues to be detected by the first sensors 30 without breakage even after the first sensors 30 switch to ON. Therefore, even if the pair of holding members 36 are advanced into the second cutting area E2 at this point, glass fragments falling due to breakage will not collide with the holding members 36.

[0078] 10(c), when the glass ribbon G is further shaped and conveyed, and the three second sensors 35 are switched from OFF to ON, the following operation is performed. That is, when, for example, a preset set time has elapsed since the three second sensors 35 were switched ON, the glass ribbon G is cut by the above-described first process by the second cutting device 3. Note that the set time here is set as the time required from when the second sensors 35 are switched ON until the entire lower end Gz of the glass ribbon G is conveyed a predetermined distance below the pressing member 41.

[0079] FIG. 11 illustrates a second example of the above process. This second example illustrates a process in which, by resuming forming after a crack or the like occurs in the glass ribbon G during the first cutting step, the left end and center of the glass ribbon G in the width direction are first formed and conveyed, and the right end of the glass ribbon G is formed and conveyed later, as shown in the same figure. In this case, as the glass ribbon G is formed and conveyed, the first sensors 30 at the left end and center first turn ON, and the first sensor 30 at the right end turns OFF, as shown in FIG. 11( a). When two first sensors 30 turn ON in this way, only the left-side holding member 36 is advanced into the second cutting area E2. When the glass ribbon G is in the formed state shown in FIG. 11( a), the vertical length of the missing portion Gw on the right side of the lower end Gz of the glass ribbon G is usually short, as shown in the figure. Therefore, in this case, three first sensors 30 eventually turn ON, as shown in FIG. 11( b). At this point, the right-side holding member 36 is advanced into the second cutting area E2. In this case, too, if the first sensor 30 that had turned ON turns OFF again after the left-side holding member 36 has been advanced, the same measures as in the first example above are taken. Then, when the glass ribbon G is further formed and conveyed downward, and the three second sensors 35 switch from OFF to ON as shown in Fig. 11(c), the glass ribbon G is cut by the above-described first process by the second cutting device 3 at the point when the above-mentioned preset set time has elapsed. Note that, even if, when forming of the glass ribbon G is resumed here, the right end portion and the central portion in the width direction of the glass ribbon G are formed and conveyed first and the left end portion in the width direction is formed and conveyed later, the glass ribbon G can be cut by the same procedure.

[0080] In the second example described above, when two first sensors 30 turn ON, only one of the holding members 36 is advanced to the second cutting area E2, but when three first sensors 30 turn ON, both of the holding members 36 may be advanced to the second cutting area E2 without advancing one of the holding members 36 to the second cutting area E2, without advancing the other of the holding members 36 to the second cutting area E2.

[0081] FIG. 12 illustrates a third example of the above process. This third example illustrates a process in which, as shown in the same figure, forming is resumed after the glass ribbon G is broken during the first cutting step, so that only the left end G1 in the width direction of the glass ribbon G is formed and conveyed. In this case, as the left end G1 in the width direction of the glass ribbon G is formed and conveyed, first, as shown in FIG. 12( a), the first sensor 30 at the left end turns ON, and the first sensors 30 at the center and right end turn OFF. When the first sensor 30 at the left end turns ON in this way, only the left-side holding member 36 is advanced into the second cutting area E2. In this case, if the first sensor 30 at the left end turns OFF again after the left-side holding member 36 has been advanced, the left-side holding member 36 is retracted and advanced in the same manner as in the first example above. Then, the left end G1 in the width direction of the glass ribbon G is further shaped while being conveyed downward, and when the second sensor 35 at the left end switches from OFF to ON as shown in Fig. 12(b), at the time when the above-mentioned preset time has elapsed, the left end G1 of the glass ribbon G is cut by the above-mentioned second process by the second cutting device 3. Note that even when forming of the glass ribbon G is resumed here, and only the right end in the width direction of the glass ribbon G is shaped while being conveyed, the right end in the width direction of the glass ribbon G can be cut by the same procedure using the right-side holding member 36.

[0082] FIG. 13 illustrates a fourth example of the above process. This fourth example illustrates a process in which, as shown in the figure, forming is resumed after the glass ribbon G is broken during the first cutting step, so that the widthwise left end G1 and widthwise right end G2 of the glass ribbon G are shaped and conveyed. In this case, as both widthwise ends G1 and G2 of the glass ribbon G are shaped and conveyed, the first sensors 30 at the left and right ends first turn ON, and the central first sensor 30 turns OFF, as shown in FIG. 13( a). When the left and right first sensors 30 turn ON in this way, the pair of holding members 36 are advanced into the second cutting area E2. In this case, if at least one of the left-end first sensor 30 and the right-end first sensor 30 turns OFF again after the pair of holding members 36 have been advanced, the corresponding holding member 36 is retracted and advanced in the same manner as in the first example above. Then, the widthwise left end G1 and widthwise right end G2 of this glass ribbon G are further shaped and transported downward, and when the second sensors 35 at the left and right ends switch from OFF to ON as shown in Figure 13(b), the widthwise left end G1 and widthwise right end G2 of the glass ribbon G are cut by the third process described above by the second cutting device 3 once the above-mentioned predetermined set time has elapsed.

[0083] In the above first to fourth examples, the three first sensors 30 constantly detect the presence or absence of the glass ribbon G. Therefore, based on the detection results by the first sensors 30 in the first detection step, it is possible to distinguish between a first state in which one of both widthwise end portions of the glass ribbon G is being shaped while being conveyed, a second state in which one of both widthwise end portions and the widthwise central portion of the glass ribbon G is being shaped while being conveyed, a third state in which both widthwise end portions of the glass ribbon G are being shaped while being conveyed, and a fourth state in which the entire widthwise portion of the glass ribbon G is being shaped while being conveyed.

[0084] Although the above first to fourth examples illustrate cases in which the glass ribbon G is cut using three first sensors 30 and three second sensors 35, the glass ribbon G can also be cut using two first sensors 30 and two second sensors 35. In this case, for each of the three first sensors 30 and three second sensors 35, the central sensor 30, 35 may be omitted and the left and right end sensors 30, 35 may be used instead. In this case, three first sensors 30 may be used and the left and right end second sensors 35 may be used, or the left and right end first sensors 30 may be used and three second sensors 35 may be used.

[0085] The above describes the glass sheet manufacturing apparatus and the manufacturing method thereof according to an embodiment of the present invention, but 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.

[0086] In the above embodiment, the glass ribbon G is formed by the overflow downdraw method, but it may also be formed by other downdraw methods such as the slot downdraw method or the redraw method.

[0087] In the above embodiment, in the first cutting step, the glass ribbon G is cut by bending along the scribe lines S, but it may be cut by other methods such as laser cleaving or laser fusing.

[0088] In the above embodiment, the second cutting device 3 is disposed below the first cutting device 2, but these devices 2, 3 may be disposed side by side so that part or all of them overlap in the vertical direction. In this case, the main body frame 31 of the second cutting device 3 is held in a fixed position, and when the first cutting device 2 is in use, the holding member 36, rotary blade 38, and pressing member 41 are retracted to positions that do not interfere with the operation of the first cutting device 2. Furthermore, the first cutting device 2 and the second cutting device 3 may be mounted (installed) on the same floor wall 23.

[0089] In the above embodiment, the holding member 36, the rotary blade 38 and the pressing member 41 are advanced and retracted without moving the main body frame 31 of the second cutting device 3, but these members 36, 38 and 41 may also be advanced and retracted while moving the main body frame 31 in the forward and backward directions.

[0090] In the above embodiment, the rotary blade 38 is used to cut the glass ribbon G, but any other cutting blade may be used as long as it has a cutting edge.

[0091] In the above embodiment, two or three first and second sensors 30, 35 are arranged in the width direction, but four or more first and second sensors 30, 35 may be arranged in the width direction.

[0092] In the above embodiment, the holding member 36 is advanced in the switching step, but if the configuration of the second cutting device 6 is different from that of the above embodiment, other components of the second cutting device (particularly the components that advance from the second evacuation area F2 to the second cutting area E1 earliest) may be advanced. Furthermore, if the means for switching from the first cutting step to the second cutting step is not a means for advancing the components of the second cutting device 6, the switching step may be performed by a means that does not involve the advancement operation. [Explanation of symbols]

[0093] 1 Glass ribbon processing equipment 2 First cutting device 3 Second cutting device 11 Forming Zone 30 First Sensor 31 Main frame 32 Holding device 34 Stress application device 35 Second Sensor 36 Retaining member 38 Rotary blade (cutting blade) 41 Pressing member E1 First cutting area E2 Second cutting area F1 First Evacuation Area F2 Second evacuation area G Glass ribbon GS Glass ribbon transport route

Claims

1. A method for manufacturing a glass sheet, comprising: a first cutting step of cutting a glass ribbon being conveyed while being formed by a first cutting device to cut out a glass sheet; and a second cutting step of cutting the glass ribbon by a second cutting device when the first cutting device is not operating, A method for manufacturing a glass plate, comprising: a first detection process for detecting the presence or absence of a glass ribbon by a sensor upstream of the first cutting device and the second cutting device in the conveying direction; and a switching process for switching from the first cutting process to the second cutting process when the absence of the glass ribbon is detected in the first detection process.

2. The method for manufacturing a glass sheet according to claim 1 , wherein the sensors are installed at a plurality of locations in the width direction of the glass ribbon, each corresponding to a different location.

3. 3. The method for manufacturing a glass sheet according to claim 1 or 2, wherein the sensors are installed corresponding to at least both widthwise end portions and a widthwise intermediate portion of the glass ribbon, and the detection results in the first detection step make it possible to distinguish between a first state in which one of both widthwise end portions of the glass ribbon is being shaped while being transported, a second state in which one of both widthwise end portions and the widthwise intermediate portion of the glass ribbon is being shaped while being transported, a third state in which both widthwise end portions of the glass ribbon are being shaped while being transported, and a fourth state in which the entire widthwise direction of the glass ribbon is being shaped while being transported.

4. 4. The method for manufacturing a glass sheet according to claim 1, wherein, in the switching step, when the absence of the glass ribbon is detected in the first detection step, components of the second cutting device are advanced from a retreat area to a cutting area.

5. 5. The method for manufacturing a glass sheet according to claim 4, wherein the component of the second cutting device is a part of all the components of the second cutting device and is a component that advances earliest among all the components when the cutting process by the second cutting device is started.

6. 6. The method for manufacturing a glass plate according to claim 5, wherein the sensors are installed corresponding to at least both widthwise ends of the glass ribbon, and the components that advance earliest are one or both of the holding members used to hold both widthwise ends of the glass ribbon during cutting in the second cutting step, and the holding member corresponding to the widthwise end of the glass ribbon detected by the sensor to be present is advanced, and the holding member corresponding to the widthwise end of the glass ribbon detected by the sensor to be absent is not advanced.

7. 7. The method for manufacturing a glass sheet according to claim 4, further comprising a second detection step of detecting the presence or absence of a glass ribbon by sensors installed corresponding to at least both widthwise ends of the glass ribbon at positions downstream in the conveying direction from the sensors used in the first detection step, and performing a cutting process of the glass ribbon using components of the second cutting device advanced in the switching step based on the detection results of the sensors.

8. 8. The method for manufacturing a glass sheet according to claim 7, wherein a component of the second cutting device includes a cutting blade used to cut the glass ribbon, and the cutting blade is pressed against the glass ribbon based on a detection result in the second detection step.

9. 9. The method for manufacturing a glass sheet according to claim 8, wherein components of the second cutting device include a pressing member that applies stress to the glass ribbon, and the pressing member is caused to apply stress to the glass ribbon based on a detection result in the second detection step.

10. A glass sheet manufacturing apparatus including: a first cutting device that cuts a glass ribbon that is being formed and transported to cut out a glass sheet; and a second cutting device that cuts the glass ribbon when the first cutting device is not operating, a sensor for detecting the presence or absence of the glass ribbon upstream of the first cutting device and the second cutting device in the conveying direction, and configured to perform a switching process for switching operation of the first cutting device to operation of the second cutting device when the sensor detects the absence of the glass ribbon.

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