Method for producing glass article

Abstract

Provided is a method for producing a glass article, the method comprising: a conveyance step P4 for conveying a glass ribbon G along a conveyance path 11; and an acquisition step P5 for acquiring a glass plate Gs from the glass ribbon G at a downstream end 11e of the conveyance path 11. The method further includes a guide step P6 in which, when a defective crack C progressing upstream in the glass ribbon G occurs in the glass ribbon G, the defective crack C is guided to a width-direction end edge Ge of the glass ribbon G. In the guide step P6, a tension difference is provided between one side part G1 and the other side part G2 in the width direction of the glass ribbon G, wherein the one side part G1 and the other side part G2 are divided at the defective crack C that serves as a boundary.

Description

Method for manufacturing glass articles

[0001] The present disclosure relates to a method for manufacturing a glass article.

[0002] Glass articles such as glass sheets and glass rolls are often manufactured from glass ribbons. Patent Document 1 discloses an example of a method for manufacturing a glass roll from a glass ribbon.

[0003] In this method, first, a glass ribbon is continuously formed from molten glass using the down-draw method. Next, the conveying direction of the formed glass ribbon is changed from the vertical direction to the horizontal direction. After that, unnecessary portions present on both sides of the glass ribbon in the width direction are cut off and removed from the glass ribbon. Finally, the glass ribbon from which the unnecessary portions have been removed is wound into a roll around a winding core to form a glass roll.

[0004] Japanese Patent Application Laid-Open No. 2022-40755

[0005] When a glass article is manufactured from a glass ribbon as described above, a production loss of the glass article may occur due to cracks that unintentionally occur in the glass ribbon (hereinafter referred to as "defective cracks").

[0006] For example, as in the embodiment shown in Fig. 6 , production loss may occur when glass sheets 200 are continuously cut from the glass ribbon 100 by repeatedly cutting the glass ribbon 100 conveyed in the A direction at the downstream end of the conveying path. In this embodiment, if the cutting of the glass sheet 200 fails, the glass ribbon 100 may break, causing a defective crack C. The defective crack C propagates toward the upstream side (direction B) of the glass ribbon 100, opposite to the conveying direction (direction A) of the glass ribbon 100. Note that one side portion 101 and the other side portion 102 in the width direction of the glass ribbon 100 shown in the same figure are separated at the defective crack C as a boundary.

[0007] When the above-described defective crack C occurs, it becomes impossible to cut a new glass sheet 200 from the glass ribbon 100 until the defective crack C is removed from the glass ribbon 100. More specifically, the defective crack C does not stop progressing upstream and continues to exist on the glass ribbon 100 unless it deviates to the width-direction edge 100a of the glass ribbon 100. Therefore, cutting of the glass sheet 200 has to be stopped until the defective crack C accidentally deviates to the width-direction edge 100a. This results in a production loss of the glass sheet 200. Therefore, there has been a demand for the establishment of a technology that can quickly remove the defective crack C from the glass ribbon 100 when the defective crack C occurs in the glass ribbon 100.

[0008] In view of the above circumstances, a technical problem to be solved is to enable rapid removal of defective cracks from a glass ribbon when the defective cracks occur in the glass ribbon when a glass article is manufactured from the glass ribbon.

[0009] A first method for manufacturing a glass article to solve the above problem is a method for manufacturing a glass article comprising a conveying step of conveying a glass ribbon along a conveying path and an acquiring step of acquiring a glass article from the glass ribbon at the downstream end of the conveying path, and further comprising a guiding step of guiding a defective crack that propagates toward the upstream side of the glass ribbon to a widthwise edge of the glass ribbon when the defective crack occurs in the glass ribbon, and is characterized in that in the guiding step, a tension difference is created between the tension generated in one side portion of the glass ribbon in the widthwise direction and the tension generated in the other side portion separated by the defective crack.

[0010] In the first method for manufacturing a glass article, as the guiding step is performed, a tension difference occurs between the tension generated in one widthwise region of the glass ribbon and the tension generated in the other widthwise region separated by the defective crack (hereinafter, the region with the greater tension will be referred to as the "high tension region"). Due to this tension difference, the defective crack propagates toward one of the widthwise end edges of the glass ribbon that is included in the high tension region, and quickly reaches that edge. Accordingly, the defective crack can be removed from the glass ribbon. Thus, according to this manufacturing method, when a defective crack occurs in the glass ribbon, the defective crack can be quickly removed from the glass ribbon.

[0011] The second glass article manufacturing method is the same as the first manufacturing method described above, except that in the induction process, a tension difference is created by accelerating the conveying speed of one of the one side section and the other side section.

[0012] In the second method for producing a glass article, the tension difference is created by accelerating the conveying speed of one of the two sections, so that the tension difference can be created quickly and reliably between the two sections. Furthermore, because the conveying speed is accelerated, unlike when the conveying speed is decelerated, the risk of wrinkles or slack in the glass ribbon occurring during the guiding step can be eliminated.

[0013] The third method for manufacturing a glass article is a method similar to the first or second manufacturing method, in which, in the guiding process, a tension difference is created by applying to one of the one side portion and the other side portion (1) an external force directed downstream in the conveying direction of the glass ribbon, or (2) an external force having a component directed downstream in the conveying direction of the glass ribbon and a component directed outward from the center in the width direction.

[0014] In the third method for producing a glass article, the external force (1) or (2) described above is applied to one of the two regions. Both of the external forces (1) and (2) have a component directed downstream in the conveying direction of the glass ribbon. This has the effect of reliably creating a tension difference between the two regions as a result of the application of the external force, and the effect of making it easier for defective cracks to propagate toward the widthwise edges of the glass ribbon.

[0015] The fourth method for manufacturing a glass article is the same as the third manufacturing method described above, except that an external force is applied to a portion of the glass ribbon located between the widthwise edge and the defective crack.

[0016] In the fourth method for manufacturing a glass article, an external force is applied to a region of the glass ribbon that is located inside the widthwise edge. Therefore, it is possible to avoid applying a load to the widthwise edge, which is a region of the glass ribbon that has low strength, when the guiding step is performed. Therefore, it is possible to eliminate the risk of new defective cracks occurring from the widthwise edge to which the load is applied.

[0017] The fifth method for manufacturing a glass article is the third or fourth manufacturing method described above, except that an external force is applied to the portion having the smaller width dimension between the one side portion and the other side portion.

[0018] In the fifth method for manufacturing a glass article, the defective crack propagates toward one of the widthwise edges of the glass ribbon that is closer to the defective crack, thereby shortening the time required for the defective crack to reach the widthwise edge and enabling the defective crack to be removed from the glass ribbon more quickly.

[0019] The sixth method for manufacturing a glass article is a method according to any one of the third to fifth manufacturing methods, in which, when applying an external force, a feed member having a feed direction that is the same as the direction of the external force is brought into contact with the glass ribbon.

[0020] In the sixth method for producing a glass article, an external force is applied by bringing the feed member into contact with the glass ribbon, and therefore the external force can be applied stably.

[0021] The seventh method for manufacturing a glass article is the same as the sixth method, except that the feed member is a roller.

[0022] In the seventh method for producing a glass article, a roller is used as the feed member, so that it is possible to apply an external force with a simple configuration.

[0023] The eighth method for manufacturing a glass article is the seventh method described above, except that the peripheral speed of the roller is made faster than the conveying speed of the glass ribbon when the roller comes into contact with the glass ribbon.

[0024] In the eighth method for producing a glass article, an external force can be applied by the frictional force between the peripheral surface of the roller and the surface of the glass ribbon (one of the one side portion and the other side portion).

[0025] A ninth method for manufacturing a glass article is any one of the third to fifth manufacturing methods described above, wherein the external force is applied by spraying gas toward the glass ribbon.

[0026] In the ninth method for manufacturing a glass article, an external force is applied by spraying gas, so that it is easy to apply an external force even if the width dimension of the area to which the external force is to be applied (one of the one side area and the other side area) is small.

[0027] The tenth method for manufacturing a glass article is any one of the first to ninth manufacturing methods described above, in which the induction process involves photographing the glass ribbon to obtain an image, and then processing the image to detect the occurrence of defective cracks.

[0028] In the tenth method for manufacturing a glass article, images of the glass ribbon are captured and image processing is used, so that defective cracks occurring in the glass ribbon can be detected with high accuracy.

[0029] The eleventh method for manufacturing a glass article is any one of the first to tenth manufacturing methods described above, wherein in the obtaining process, the glass ribbon is repeatedly cut in the width direction to continuously obtain glass plates as glass articles.

[0030] In the eleventh method for producing a glass article, the glass ribbon is repeatedly cut in the width direction, and therefore defective cracks are likely to occur at the edges (cut edges) formed in the glass ribbon as a result of cutting. Therefore, the present production method makes it possible to preferably enjoy the effect of being able to quickly remove defective cracks from the glass ribbon.

[0031] A twelfth method for manufacturing a glass article is a method in which, in any one of the first to eleventh manufacturing methods described above, the glass ribbon has a thickness of 200 μm or less, and is subjected to a forming process, a conveying direction changing process after the forming process, and a cutting process of unnecessary portions after the changing process of the conveying direction, and then is supplied to a conveying process, in which the glass ribbon is formed while being drawn out in the vertical direction from molten glass supplied to a forming body in the forming process, in which the conveying direction changing process changes the conveying direction of the glass ribbon after the forming process from the vertical direction to the horizontal direction, and in which the cutting process of unnecessary portions is performed by cutting and removing unnecessary portions present on one side and the other side of the width direction of the glass ribbon from the glass ribbon.

[0032] In the twelfth method for producing a glass article, the thickness of the glass ribbon is extremely thin, at 200 μm or less, and the unnecessary portion cutting step is performed, so that defective cracks are likely to occur in the glass ribbon that has undergone the unnecessary portion cutting step. Therefore, with this production method, it is possible to more suitably enjoy the effect of being able to quickly remove defective cracks from the glass ribbon.

[0033] A thirteenth method for manufacturing a glass article for solving the above problem is a method for manufacturing a glass article comprising a conveying step of conveying a glass ribbon along a conveying path and an acquiring step of acquiring a glass article from the glass ribbon at the downstream end of the conveying path, and further comprising a guiding step of guiding a defective crack that propagates toward the upstream side of the glass ribbon to a widthwise edge of the glass ribbon when the defective crack occurs in the glass ribbon, wherein the guiding step is characterized in that an external force for guiding is applied to one of one side portion and the other side portion in the widthwise direction of the glass ribbon separated by the defective crack as a boundary.

[0034] The thirteenth method for manufacturing a glass article can achieve the same effects and advantages as the first manufacturing method described above.

[0035] According to the method for manufacturing a glass article according to the present disclosure, when a glass article is manufactured from a glass ribbon, if a defective crack occurs in the glass ribbon, it is possible to quickly remove the defective crack from the glass ribbon.

[0036] Fig. 1 is a side view showing a method for manufacturing a glass article; Fig. 2 is a plan view showing a method for manufacturing a glass article; Fig. 3 is a plan view showing a guiding step; Fig. 4 is a plan view showing the guiding step; Fig. 5 is a side view showing a modified example of the guiding step; Fig. 6 is a plan view for explaining problems in the prior art.

[0037] Hereinafter, a method for manufacturing a glass article according to an embodiment will be described with reference to the accompanying drawings. Note that the X direction, Y direction, and Z direction shown in each drawing referred to in the description of the embodiment are directions that are perpendicular to one another.

[0038] 1 and 2 , in the method for manufacturing a glass article according to this embodiment, a glass sheet Gs as a glass article is cut out from a glass ribbon G formed using a downdraw method (an overflow downdraw method in the illustrated example). This manufacturing method includes, as main steps, a forming step P1, a conveying direction changing step P2, an unnecessary portion cutting step P3, a conveying step P4, and an obtaining step P5.

[0039] In the forming step P1, a glass ribbon G is formed while being drawn out in the vertical direction (Z direction) from the molten glass MG supplied to the forming body 1. A roller group 2 arranged in multiple vertical stages is used to draw out the glass ribbon G. The roller group 2 includes edge rollers 3, annealer rollers 4, and support rollers 5.

[0040] The edge rollers 3 contact the widthwise ends of the glass ribbon G directly below the forming body 1 to suppress shrinkage of the glass ribbon G in the width direction (X direction). The annealer rollers 4 guide the downward movement of the glass ribbon G that is being slowly cooled to a temperature below the strain point in an annealing furnace (not shown). The support rollers 5 support and pull downward the glass ribbon G whose temperature has been reduced to near room temperature in a cooling chamber (not shown).

[0041] Unwanted portions Gx are present on one side and the other side of the formed glass ribbon G in the width direction (in Figure 2, the boundary between the unwanted portions Gx and other portions is indicated by a two-dot chain line). The unwanted portions Gx are portions that are cut off and removed from the glass ribbon G in an unwanted portion cutting process P3, which is executed downstream of the forming process P1. The unwanted portions Gx include ear portions that are thicker than other portions of the glass ribbon G. The thickness of the glass ribbon G (the thickness of the portions excluding the ear portions) is, for example, 200 μm or less, 100 μm or less, or 50 μm or less.

[0042] In the conveying direction changing step P2, the conveying direction of the glass ribbon G after the forming step P1 is changed from the vertical direction to the horizontal direction (Y direction). To change the conveying direction of the glass ribbon G, a roller conveyor 6 consisting of a plurality of rollers is used.

[0043] After the conveying direction change process P2, the glass ribbon G is transported downstream by a belt conveyor 7 and a strip-shaped protective sheet 9 (e.g., a strip-shaped resin sheet) moving on a support table 8, and sent to the unnecessary portion cutting process P3.

[0044] In the unnecessary portion cutting process P3, the unnecessary portions Gx are cut and removed from the glass ribbon G. A laser cutting device 10 is used to cut off the unnecessary portions Gx. A laser L is irradiated from the device 10 toward the glass ribbon G, and the unnecessary portions Gx are cut off by continuously cutting the glass ribbon G along the longitudinal direction (Y direction). The cut unnecessary portions Gx are separated from the conveying path 11 of the glass ribbon G downstream of the unnecessary portion cutting process P3 and discarded.

[0045] In the conveying step P4, the glass ribbon G after the unnecessary portion cutting step P3 (the glass ribbon G from which the unnecessary portion Gx has been removed) is conveyed along the conveying path 11 and sent to the obtaining step P5. To convey the glass ribbon G in the conveying step P4, a strip-shaped protective sheet 9 moving on a belt conveyor 12 and a board 13 is used.

[0046] Above the conveying path 11 for the glass ribbon G, an imaging device 14 and a pair of rollers 15, 15 (feeding members) used in a guiding process P6 described later are arranged.

[0047] The pair of rollers 15, 15 are arranged corresponding to one side and the other side in the width direction of the glass ribbon G, respectively. Each roller 15 is located between the width direction center and the width direction edge Ge of the glass ribbon G when viewed from the Z direction. Both of the pair of rollers 15, 15 are located above the board 13. Each roller 15 can move in the vertical direction, and can contact and separate from the surface of the glass ribbon G as it moves. Each roller 15 contacts the surface of the glass ribbon G when used in the guiding process P6, and separates from the surface when not in use. Details of the function of the imaging device 14 and the operation of the pair of rollers 15, 15 in the guiding process P6 will be described later.

[0048] In the obtaining process P5, the glass ribbon G is repeatedly cut in the width direction (X direction) at the downstream end 11e of the conveying path 11, thereby continuously obtaining glass sheets Gs from the glass ribbon G. Cutting of the glass ribbon G along the width direction can be performed using a known cutting device or by cutting work by an operator. The multiple glass sheets Gs obtained from the glass ribbon G are packaged after being alternately stacked with, for example, buffer sheets.

[0049] In addition to the above-mentioned steps P1 to P5, this manufacturing method further includes an induction step P6 shown in FIGS. 3, 4a and 4b.

[0050] As shown in FIG. 3 , the guiding process P6 is a process executed when a defective crack C propagating toward the upstream side (direction D1) of the glass ribbon G occurs. In the guiding process P6, the defective crack C is guided to the widthwise edge Ge of the glass ribbon G, and the defective crack C is removed from the glass ribbon G accordingly. In this embodiment, an example is given of a case where a defective crack C occurs from the cut end (the leading end of the glass ribbon G) when the glass ribbon G is cut in the width direction in the obtaining process P5. Note that, during the execution of the guiding process P6, the execution of the obtaining process P5 is interrupted to stop the acquisition of the glass sheet Gs from the glass ribbon G. Furthermore, during the execution of the guiding process P6, the glass ribbon G that has reached the downstream end 11e of the conveying path 11 is continuously discarded.

[0051] The defective crack C is a crack that propagates in the opposite direction to the conveying direction of the glass ribbon G. When this defective crack C occurs in the glass ribbon G, one side region G1 and the other side region G2 in the width direction of the glass ribbon G, which are separated by the defective crack C, are separated. In the present embodiment, one occurrence mode of the defective crack C is that the defective crack C occurs closer to one side in the width direction of the glass ribbon G. As a result, the width dimension W1 of the one side region G1 is smaller than the width dimension W2 of the other side region G2. Of course, there are also cases where the defective crack C occurs near the center in the width direction of the glass ribbon G (cases where W1 and W2 are approximately the same dimension).

[0052] In the guiding process P6, it is first necessary to detect the occurrence of a defective crack C in the glass ribbon G. To detect the defective crack C, an imaging device 14 that images the glass ribbon G and an image processing device (not shown) that processes the captured image are used.

[0053] The imaging device 14 has a field of view that covers a predetermined range in the X direction and the Y direction. In the X direction, the field of view covers the entire width of the glass ribbon G after the unnecessary portion cutting process P3 (the entire width after the unnecessary portion Gx has been cut off). In the Y direction, the field of view covers at least a portion of the longitudinal section of the glass ribbon G. This allows the imaging device 14 to reliably capture the defective crack C in its field of view when a defective crack C occurs in the glass ribbon G, regardless of its position in the width direction (whether it is closer to one side or the other side in the width direction).

[0054] The image processing device can detect the defective cracks C by, for example, using a differential image (imaging the difference in pixel values ​​between the captured image and an image captured previously) based on the image captured by the imaging device 14. Of course, other image processing may be used to detect the defective cracks C as long as it is possible to determine the presence or absence of the defective cracks C.

[0055] When the occurrence of a bad crack C in the glass ribbon G is detected, the bad crack C is guided to the widthwise edge Ge of the glass ribbon G, as shown in Fig. 4a. To guide the bad crack C to the widthwise edge Ge, one roller 15 of the pair of rollers 15, 15 is used. Note that Figs. 4a and 4b illustrate only one roller 15 of the pair of rollers 15, 15 that is used to guide the bad crack C (the other roller 15 is not shown).

[0056] The one roller 15 is the roller 15 arranged above the one side region G1, which is the region with the smaller width dimension between the one side region G1 and the other side region G2 of the glass ribbon G. In the guiding process P6, as shown in FIGS. 4a and 4b , the roller 15 is brought into contact with the one side region G1, thereby applying an external force F to the one side region G1 in a downstream direction in the conveying direction of the glass ribbon G. At this time, the feed direction of the roller 15 is the same as the direction of the external force F to be applied, and further, the peripheral speed V1 of the roller 15 is set to be faster than the conveying speed V2 of the glass ribbon G. The position at which the external force F is applied is between the widthwise edge Ge and the defective crack C in the X direction. The position at which the external force F is applied is sufficiently separated in the Y direction from the position at which the unnecessary portion cutting process P3 is performed. Therefore, the risk of the properties of the widthwise edge Ge of the glass ribbon G being deteriorated due to the application of the external force F is eliminated.

[0057] When the roller 15 is brought into contact with the one-side region G1, the one-side region G1 is sandwiched in the thickness direction (Z direction) between the roller 15 and the board 13. In other words, during the execution of the guiding step P6, the board 13 functions as a support member that supports the roller 15 via the glass ribbon G (one-side region G1).

[0058] In the present embodiment, the external force F directed toward the downstream side in the conveying direction of the glass ribbon G is applied to the one-side region G1, but this is not limited to this. An external force F having a component directed toward the downstream side in the conveying direction of the glass ribbon G and a component directed outward from the center side in the width direction may be applied to the one-side region G1. In other words, the direction of the external force F may be inclined with respect to the conveying direction of the glass ribbon G, and the magnitude of the inclination (angle θ shown in FIG. 4a ) may be less than 90°. In this case, the feed direction of the roller 15 is set to the same direction as the direction of the external force F to be applied, and further, the component in the conveying direction of the glass ribbon G at the circumferential speed V1 of the roller 15 is set to be faster than the conveying speed V2 of the glass ribbon G.

[0059] When the external force F is applied to the one-side region G1 as described above, the conveying speed of the one-side region G1 is accelerated. This causes a tension difference between the one-side region G1 and the other-side region G2. Specifically, the tension T1 acting on the one-side region G1 becomes greater than the tension T2 acting on the other-side region G2. Due to this tension difference, the defective crack C propagates (progresses in the D2 direction) toward the edge Ge included in the one-side region G1, one of the widthwise end edges Ge, Ge of the glass ribbon G, and quickly reaches the edge Ge. When the defective crack C reaches the widthwise edge Ge, the propagation of the defective crack C toward the upstream side is stopped. Thereafter, a portion of the glass ribbon G upstream of the defective crack C is cut in the width direction. This separates the section in the longitudinal direction of the glass ribbon G where the defective crack C exists from the section where it does not exist. Accordingly, the defective crack C is removed from the glass ribbon G, and the guiding process P6 is completed. After the completion of the guidance step P6, the execution of the interrupted acquisition step P5 is resumed.

[0060] Here, it is preferable to use, for example, butyl rubber, nitrile rubber, or the like as the material for the peripheral surface of the roller 15 (the surface that comes into contact with the glass ribbon G) from the viewpoint of suitably applying the above-mentioned external force F. Furthermore, from the viewpoint of preventing the tension T1 acting on the glass ribbon G (one side region G1) from becoming excessive, it is preferable to set the peripheral speed V1 of the roller 15 within a range of 101% to 500% of the conveying speed V2 of the glass ribbon G as the reference.

[0061] The following modifications can also be applied to the above embodiment.

[0062] In the above embodiment, when a defective crack C that has occurred in the glass ribbon G is guided to the widthwise edge Ge, one of a pair of rollers 15, 15 is used. However, one of the rollers 15 of the pair of rollers 15, 15 does not necessarily need to be present originally, and only a single roller 15 may be arranged. This single roller 15 may be arranged corresponding to either one side or the other side in the width direction of the glass ribbon G. Regardless of whether a single roller 15 is arranged corresponding to either one side or the other side, as long as there is a tension difference between the tension T1 and the tension T2 (the magnitude relationship between T1 and T2 may be reversed), the defective crack C can be guided to the widthwise edge Ge regardless of the position where the defective crack C occurs (whether closer to one side or the other side in the width direction).

[0063] In the above embodiment, the occurrence of the defective crack C is exemplified by a case in which the defective crack C occurs from the cut end (the leading end of the glass ribbon G) when the glass ribbon G is cut in the width direction in the acquisition process P5. Of course, the occurrence of the defective crack C is not limited to this. The defective crack C may occur from the width direction edge Ge of the glass ribbon G after the unnecessary portion cutting process P3, or may occur in the glass ribbon G upstream of the unnecessary portion cutting process P3. In these cases, the guiding process P6 may be executed. Even in these cases, if the guiding process P6 is executed with the same arrangement of the imaging device 14 and the pair of rollers 15, 15 as in the above embodiment, the defective crack C that occurs in the glass ribbon G can be guided to the width direction edge Ge.

[0064] In the above embodiment, the external force F is applied by bringing the roller 15 into contact with one side region G1 of the glass ribbon G. However, this is not limited to this, and as shown in Fig. 5 , the external force F may be applied by air A (gas) sprayed from a spray nozzle 16 toward the glass ribbon G on the board 13. The spray nozzle 16 is directed from above the conveyance path 11 toward the downstream side in the conveyance direction of the glass ribbon G. Furthermore, instead of the air A sprayed from the roller 15 or the spray nozzle 16, the external force F may be applied manually by an operator.

[0065] In the above embodiment, the conveying speed of the one-side region G1 is accelerated to provide a tension difference between the one-side region G1 and the other-side region G2 of the glass ribbon G. However, this is not limited to this, and the conveying speed of the one-side region G1 may be decelerated to provide a tension difference between the one-side region G1 and the other-side region G2.

[0066] In the above embodiment, the glass sheets Gs serving as glass articles are cut out from the glass ribbon G to be manufactured, but the glass ribbon G may be wound into a roll to manufacture a glass roll.

[0067] REFERENCE SIGNS LIST 1 Formed body 11 Conveying path 11e Downstream end 15 Roller A Air C Defective crack F External force G Glass ribbon G1 One side portion G2 Other side portion Ge Width direction edge Gs Glass sheet Gx Unwanted portion MG Molten glass P1 Forming process P2 Conveying direction changing process P3 Unwanted part cutting process P4 Conveying process P5 Obtaining process P6 Guiding process T1, T2 Tension V1 Circumferential speed V2 Conveying speed W1, W2 Width dimension

Claims

1. A method for manufacturing a glass article, comprising: a conveying step of conveying a glass ribbon along a conveying path; and an acquiring step of acquiring a glass article from the glass ribbon at a downstream end of the conveying path, further comprising a guiding step of guiding a defective crack that propagates toward the upstream side of the glass ribbon to a widthwise edge of the glass ribbon when the defective crack occurs in the glass ribbon, wherein the guiding step provides a tension difference between the tension generated in one side portion of the glass ribbon in the width direction and the tension generated in the other side portion separated by the defective crack.

2. The method for manufacturing a glass article as described in claim 1, characterized in that in the induction process, the tension difference is created by accelerating the conveying speed of one of the one-side portion and the other-side portion.

3. The method for manufacturing a glass article as described in claim 2, characterized in that in the guiding process, the tension difference is created by applying to one of the one side portion and the other side portion (1) an external force directed downstream in the conveying direction of the glass ribbon, or (2) an external force having a component directed downstream in the conveying direction of the glass ribbon and a component directed outward from the center in the width direction.

4. A method for manufacturing a glass article as described in claim 3, characterized in that the external force is applied to a portion located between a widthwise edge of the glass ribbon and the defective crack.

5. A method for manufacturing a glass article as set forth in claim 3 or 4, characterized in that the external force is applied to one of the one-side portion and the other-side portion, whichever has a smaller width dimension.

6. A method for manufacturing a glass article as described in claim 3 or 4, characterized in that when applying the external force, a feed member having a feed direction that is in the same direction as the direction of the external force is brought into contact with the glass ribbon.

7. The method for manufacturing a glass article according to claim 6, wherein the feeding member is a roller.

8. The method for manufacturing a glass article according to claim 7, characterized in that the peripheral speed of the roller is set to be faster than the conveying speed of the glass ribbon when the roller is in contact with the glass ribbon.

9. The method for manufacturing a glass article according to claim 3 or 4, characterized in that when applying the external force, a gas is sprayed toward the glass ribbon.

10. A method for manufacturing a glass article as described in any one of claims 1 to 4, characterized in that in the induction process, the glass ribbon is photographed to obtain an image, and the image is processed to detect the occurrence of the defective cracks.

11. A method for manufacturing a glass article as described in any one of claims 1 to 4, characterized in that in the obtaining step, the glass ribbon is repeatedly cut in the width direction to continuously obtain glass plates as the glass article.

12. A method for manufacturing a glass article as described in any one of claims 1 to 4, characterized in that the glass ribbon has a thickness of 200 μm or less, and is subjected to the conveying step through a forming step, a conveying direction changing step after the forming step, and a cutting step of unnecessary portions after the conveying direction changing step, wherein in the forming step, the glass ribbon is formed while being pulled out in the vertical direction from molten glass supplied to a forming body, in the conveying direction changing step, the conveying direction of the glass ribbon after the forming step is changed from the vertical direction to the horizontal direction, and in the cutting step, unnecessary portions present on one side and the other side of the width direction of the glass ribbon are cut off and removed from the glass ribbon.

13. A method for manufacturing a glass article, comprising: a conveying step of conveying a glass ribbon along a conveying path; and an acquiring step of acquiring a glass article from the glass ribbon at a downstream end of the conveying path, further comprising a guiding step of guiding a defective crack that propagates toward the upstream side of the glass ribbon to a widthwise edge of the glass ribbon when the defective crack occurs in the glass ribbon, wherein the guiding step includes applying an external force for guiding to one of one side portion and the other side portion in the width direction of the glass ribbon that are separated by the defective crack as a boundary.

Images