Method for manufacturing glass article

Abstract

The present invention provides a method for manufacturing a glass article, which prevents the occurrence of blank exhaustion and reliably continues the production of the glass article. The method for manufacturing a glass article includes: a grasping step (S6) of grasping the state of a glass raw material on molten glass in a melting furnace; a measurement step (S7) for measuring the liquid level of the molten glass in the transfer device; and a determination step (S8) for determining the state of the glass raw material on the molten glass and the liquid level of the molten glass. In the determination step (S8), when it is determined that the glass raw material on the molten glass increases and the liquid level of the molten glass decreases, a first feeding step in which the glass raw material is continuously fed into the melting furnace at a first average feeding speed is stopped. And executing a second feeding step of feeding the glass raw material at a second average feeding speed slower than the first average feeding speed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a glass article. Background Art

[0002] In a method for manufacturing glass products such as glass fibers and glass plates, for example, the method includes: a charging step of continuously charging glass raw materials into a melting furnace; a melting step of heating and melting the glass raw materials charged into the melting furnace to generate molten glass; a discharging step of discharging the molten glass generated in the melting furnace to the outside of the melting furnace; a transferring step of transferring the molten glass discharged to the outside of the melting furnace by a transferring device; and a forming step of forming a glass product from the molten glass transferred by the transferring device (for example, refer to Patent Document 1).

[0003] In the above-mentioned manufacturing method, the glass raw material put into the melting furnace is put into the liquid surface of the molten glass that has been melted previously. As a result, a material layer composed of unmelted glass raw material is formed on the liquid surface of the molten glass, and the material layer is heated and melted to gradually generate molten glass.

[0004] The material layer is heated and melted, for example, by burning a gas fuel with a burner disposed above the liquid surface of the molten glass or by heating the molten glass with electricity with electrodes immersed in the molten glass (see, for example, Patent Document 1).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2022-183902 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the above-mentioned manufacturing method, when the material layer is too thick or the material pile contained in the material layer becomes large, the temperature in the melting furnace (for example, the top temperature in the melting furnace, the ambient air temperature, the temperature of the molten glass) decreases, and the glass raw materials in the material layer are difficult to melt. As a result, the liquid level of the molten glass in the melting furnace decreases, and there is a possibility that the molten glass in the melting furnace and the transfer device disappears, that is, the so-called blank is exhausted. The exhaustion of blanks causes a serious problem that the production of glass products cannot be continued.

[0010] An object of the present invention is to prevent the occurrence of blank depletion and to reliably continue the production of glass products.

[0011] Solutions to Solve Problems

[0012] (1) The present invention made to solve the above-mentioned problems is a method for manufacturing a glass article, comprising: a first charging step of continuously charging glass raw materials into a melting furnace at a first average charging speed; a melting step of heating and melting the glass raw materials charged into the melting furnace to generate molten glass; a discharging step of discharging the molten glass generated in the melting furnace to the outside of the melting furnace; a transferring step of transferring the molten glass discharged to the outside of the melting furnace by a transferring device; and a forming step of forming a glass article from the molten glass transferred by the transferring device, wherein the method for manufacturing a glass article comprises: a grasping step of grasping the state of the glass raw materials on the molten glass in the melting furnace; a measuring step of measuring the liquid level of the molten glass in at least one of the melting furnace and the transferring device; and a judging step of judging the state of the glass raw materials on the molten glass and the liquid level of the molten glass based on the results of the grasping step and the measuring step, and when it is judged in the judging step that the glass raw materials on the molten glass increase and the liquid level of the molten glass decrease, the first charging step is stopped and a second charging step of charging the glass raw materials at a second average charging speed slower than the first average charging speed is executed.

[0013] Thus, in the second input process, the glass raw material is input at a second average input speed slower than the first average input speed in the first input process, so that the temperature in the melting furnace (e.g., the top temperature in the melting furnace, the atmosphere temperature, and the temperature of the molten glass) rises, and the heating and melting of the glass raw material on the molten glass is promoted. As a result, the state of increasing glass raw material on the molten glass is alleviated, and the liquid level of the molten glass can be suppressed from further decreasing. Therefore, even when the glass raw material on the molten glass increases, the blank is prevented from being exhausted, and the production of glass articles can be reliably continued.

[0014] (2) In the configuration of (1) above, it is preferred that the glass raw material is intermittently added in the second adding step.

[0015] In this manner, the second feeding step can be reliably performed even with a feeding machine that cannot finely adjust the feeding speed of the glass-making raw material.

[0016] (3) In the configuration of (1) or (2) above, preferably, in the measuring step, a liquid level of the molten glass in the transfer device is measured.

[0017] Goblet depletion is more likely to occur in the transfer device than in the melting furnace. Therefore, in the determination step, if the measurement result of the liquid level of the molten glass in the transfer device is used, the occurrence of goblet depletion can be reliably prevented.

[0018] (4) In the configuration of (3) above, preferably, in the determination step, when the liquid level of the molten glass in the transfer device drops below a threshold value, it is determined that the liquid level of the molten glass has dropped, and the threshold value is 80 to 95% of the liquid level when the liquid level is stable.

[0019] In this way, the occurrence of blank depletion can be prevented more reliably.

[0020] (5) In any one of the above-mentioned structures (1) to (4), in the second charging step, it is preferable that the glass raw material on the molten glass is reduced while the liquid surface level of the molten glass is maintained in a lowered state.

[0021] In this way, the occurrence of raw material depletion can be more reliably prevented, and the temperature in the melting furnace can be reliably increased, thereby further promoting heating and melting of the glass raw material in the melting furnace.

[0022] (6) In any one of the above-mentioned structures (1) to (5), it is preferred that, when it is determined in the determination step that the glass raw material on the molten glass has decreased due to the second feeding step, the second feeding step is stopped, and a third feeding step of feeding the glass raw material while gradually increasing the feeding speed from the second feeding step is executed.

[0023] In this manner, the liquid surface level of the molten glass can be raised and restored to the original state while suppressing a decrease in the temperature in the melting furnace.

[0024] (7) In the configuration of (6) above, when it is determined in the determination step that the liquid surface level of the molten glass has risen due to the third charging step, it is preferable that the third charging step be stopped and the first charging step be restarted.

[0025] In this way, the production of glass articles can be stabilized.

[0026] Effects of the Invention

[0027] According to the present invention, the occurrence of blank depletion is prevented and production of glass articles can be reliably continued. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a side view which shows the manufacturing apparatus of the glass article which concerns on 1st Embodiment.

[0029] Figure 2 It is a cross-sectional view of the melting furnace of the first embodiment (in a stable state).

[0030] Figure 3 This is a flowchart of the method for producing a glass article according to the first embodiment.

[0031] Figure 4This is a flowchart of the method for producing a glass article according to the first embodiment.

[0032] Figure 5 It is a cross-sectional view of the melting furnace according to the first embodiment (in a non-stationary state).

[0033] Figure 6 It is a cross-sectional view of the clarification tank of the first embodiment (in a stable state).

[0034] Figure 7 It is a cross-sectional view of the clarification tank of the first embodiment (in a non-stationary state).

[0035] Figure 8 This is a flowchart of the method for producing a glass article according to the first embodiment.

[0036] Fig. 9 This is a graph illustrating the time transition of the feeding speed in the feeding process.

[0037] Fig.10 It is a cross-sectional view of the melting furnace according to the first embodiment (in a non-stationary state).

[0038] Fig.11 This is a graph showing a modified example of the time transition of the feeding speed in the first feeding step.

[0039] Fig.12 This is a graph showing a modified example of the time transition of the feeding speed in the second feeding step.

[0040] Fig.13 This is a graph showing a modified example of the time transition of the feeding speed in the feeding process.

[0041] Fig.14 It is a cross-sectional view of the melting furnace of the second embodiment (in a stable state).

[0042] Description of Reference Numerals

[0043] 1 Glass object manufacturing device

[0044] 2 Melting furnace

[0045] 3 Transfer device

[0046] 4 Forming device

[0047] 5 Clarification tank

[0048] 5a Discharge section

[0049] 6 Mixing tank

[0050] 7 cauldron

[0051] 8 Upstream connection pipeline

[0052] 9 Midstream connecting pipeline

[0053] 10 Cooling pipes

[0054] 11 formed body

[0055] 14 Input port

[0056] 15. Input machine

[0057] 16 Exhaust port

[0058] 17 Electrode

[0059] 18 Level

[0060] 21 Bubble level

[0061] 22 Piping

[0062] Ga glass raw materials

[0063] Gb Stockpile

[0064] Gm Molten glass

[0065] Gma liquid level

[0066] Gr Glass Ribbon

[0067] S1 Input process

[0068] S11 First input process

[0069] S12 Second input process

[0070] S13 The third input process

[0071] S2 Melting Process

[0072] S3 discharge process

[0073] S4 Transfer process

[0074] S5 Forming process

[0075] S6 Mastering the process

[0076] S7 Measurement Process

[0077] S8: Determination process. DETAILED DESCRIPTION

[0078] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the same reference numerals are used for the corresponding components in each embodiment, so that repeated descriptions are sometimes omitted. In the case where only a part of the structure is described in each embodiment, the structure of other embodiments previously described can be applied to the other parts of the structure. In addition, not only the combination of structures explicitly stated in the description of each embodiment, but also the structures of multiple embodiments can be partially combined with each other even if not explicitly stated, as long as there is no particular obstacle in the combination.

[0079] (First embodiment)

[0080] like Figure 1 As shown, the manufacturing device 1 of the glass article of the first embodiment comprises: a melting furnace 2, which is arranged at the upstream end and generates molten glass Gm; a transfer device 3, which transfers the molten glass Gm flowing out of the melting furnace 2 toward the downstream side; and a forming device 4, which forms a glass ribbon Gr from the molten glass Gm transferred by the transfer device 3.

[0081] The transfer device 3 includes a clarification tank 5, a stirring tank 6, and a kettle 7 in order from the upstream side. The clarification tank 5 is connected to the melting furnace 2 via an upstream connection pipe 8. The stirring tank 6 is connected to the clarification tank 5 via a midstream connection pipe 9. The kettle 7 is connected to the stirring tank 6 via a cooling pipe 10.

[0082] The molten glass Gm generated in the melting furnace 2 is clarified in the clarification tank 5. A discharge portion 5a for discharging bubbles in the molten glass Gm in the clarification tank 5 is provided at the upper portion of the downstream end portion of the clarification tank 5. It should be noted that a plurality of discharge portions 5a may be provided in the clarification tank 5.

[0083] In the stirring tank 6 , the molten glass Gm subjected to the clarification treatment is stirred, and the molten glass Gm is homogenized. In addition, a plurality of stirring tanks 6 may be provided in the transfer path of the transfer device 3 .

[0084] In the cooling duct 10 , the molten glass Gm subjected to the homogenization treatment is cooled, and the viscosity and the like of the molten glass Gm are adjusted.

[0085] In the kettle 7 , the viscosity, flow rate, and the like of the molten glass Gm adjusted in the cooling duct 10 are further adjusted.

[0086] In the forming device 4, a forming process of forming a band-shaped glass ribbon Gr from the molten glass Gm adjusted in the kettle 7 is performed. In the present embodiment, the forming device 4 includes: a forming body 11 that forms the glass ribbon Gr by flowing the molten glass Gm down by an overflow down-draw method; and a large-diameter introduction pipe 12 that guides the molten glass Gm to the forming body 11. The molten glass Gm is supplied from the kettle 7 of the transfer device 3 to the introduction pipe 12 through a small-diameter pipe 13.

[0087] After passing through the annealing furnace, the glass ribbon Gr is cut into a predetermined size by a cutting device and becomes a plate glass as a glass article. Plate glass has a thickness of, for example, 0.01 to 2 mm and is used as a glass substrate or cover glass for displays such as liquid crystal displays and organic EL displays. It should be noted that the forming device 4 may also perform other down-drawing methods such as a slit down-drawing method, or may perform methods other than the down-drawing method such as a float method.

[0088] As the molten glass Gm, for example, silicate glass, silica glass, borosilicate glass, soda-lime glass, aluminosilicate glass, alkali-free glass, aluminosilicate glass, etc. are used. It should be noted that the material of the plate glass is substantially the same as that of the molten glass Gm. When the plate glass is aluminosilicate glass, it can also be chemically strengthened glass.

[0089] like Figure 2 As shown in FIG. 1 , glass raw material Ga is heated and melted in a melting furnace 2 to generate molten glass Gm. The glass raw material Ga may contain cullet (recycled glass) in addition to natural raw materials and chemically generated raw materials.

[0090] The front wall 2a of the melting furnace 2 is provided with an inlet 14. An inlet machine 15 for inserting glass raw material Ga into the melting furnace 2 is provided at the inlet 14. The glass raw material Ga is inserted into the liquid surface Gma of the molten glass Gm that has been melted previously by the inlet machine 15. A material layer consisting of unmelted glass raw material Ga is formed on the liquid surface Gma of the molten glass Gm. As the inlet machine 15, for example, a screw inlet machine, a pusher inlet machine, etc. can be used. In the present embodiment, the case where the inlet machine 15 is a screw inlet machine is illustrated. In the case of the screw inlet machine, the material layer includes a material pile Gb. The material pile Gb is formed by piling up the glass raw material Ga supplied by the screw inlet machine. The inlet 14 and the inlet machine 15 can also be provided with a plurality of inlets 14 and the inlet machine 15 in the melting furnace 2. In this case, a material pile Gb is formed in each inlet machine 15.

[0091] A discharge port 16 for discharging the molten glass Gm is provided on the rear wall 2b of the melting furnace 2. The upstream connection duct 8 is connected to the discharge port 16, and the molten glass Gm is sequentially supplied to the downstream side.

[0092] A plurality of electrodes 17 are provided on the bottom wall 2c of the melting furnace 2. The electrodes 17 are immersed in the molten glass Gm and electrically heat the molten glass Gm. The electrodes 17 are formed, for example, of molybdenum (Mo) or the like. It should be noted that the electrodes 17 may also be provided on the side wall of the melting furnace 2 or the like in a state immersed in the molten glass Gm. In addition, the heating method in the melting furnace 2 is not limited to the all-electric melting method using only the electrical heating based on the electrodes 17. For example, it may also be a method of heating only by the combustion (burner) of a gas fuel (for example, a hydrocarbon gas fuel such as natural gas, a hydrogen fuel, an ammonia fuel, etc.) from above the liquid surface Gma of the molten glass Gm, and a method of heating by electrical heating and the combustion of a gas fuel, etc.

[0093] Next, a method for producing a glass article according to the first embodiment will be described. This production method is performed using the above-mentioned production apparatus 1 .

[0094] like Figure 3 As shown, the manufacturing method includes: a charging step S1, charging glass raw material Ga into the melting furnace 2; a melting step S2, heating and melting the glass raw material Ga charged into the melting furnace 2 to generate molten glass Gm; a discharging step S3, discharging the molten glass Gm generated in the melting furnace 2 to the outside of the melting furnace 2; a transferring step S4, transferring the molten glass Gm discharged to the outside of the melting furnace 2 by using a transferring device 3; and a forming step S5, forming a glass ribbon Gr from the molten glass Gm transferred by the transferring device 3.

[0095] like Figure 4 As shown, the manufacturing method also includes: a grasping step S6, which grasps the state of the glass raw material Ga on the molten glass Gm in the melting furnace 2; a measuring step S7, which measures the liquid level of the molten glass Gm in the transfer device 3; and a judgment step S8, which judges the state of the glass raw material Ga on the molten glass Gm and the liquid level of the molten glass Gm based on the results of the grasping step S6 and the measuring step S7.

[0096] like Figure 2 as well as Figure 5 As shown, in the grasping step S6, for example, the state of the glass raw material Ga on the molten glass Gm is grasped based on the height of the pile Gb. The height of the pile Gb is measured, for example, by visual observation, a camera, etc., through a through hole X1 provided on a wall portion (e.g., a side wall) of the melting furnace 2 at a position higher than the liquid level Gma of the molten glass Gm. The position of the through hole X1 is not particularly limited as long as the height of the pile Gb can be measured.

[0097] like Figure 6 as well as Figure 7As shown, in the measuring step S7, the liquid level of the molten glass Gm in the clarification tank 5 included in the transfer device 3 is measured. The liquid level of the molten glass Gm is measured by contact, for example, using a level 18. Specifically, the level 18 is inserted from the discharge portion 5a to a predetermined position in the clarification tank 5 and then withdrawn, and the liquid level of the molten glass Gm is measured based on the adhesion range of the molten glass Gm in the level 18. The level 18 is preferably made of platinum or a platinum alloy.

[0098] The liquid level of the molten glass Gm in the melting furnace 2 is correlated with the liquid level of the molten glass Gm in the transfer device 3 such as the clarification tank 5. That is, if the liquid level of the molten glass Gm in the melting furnace 2 decreases from the liquid level H0 when it is stable, the liquid level of the molten glass Gm in the transfer device 3 such as the clarification tank 5 also decreases from the liquid level when it is stable. On the other hand, if the liquid level of the molten glass Gm in the melting furnace 2 increases, the liquid level of the molten glass Gm in the transfer device 3 such as the clarification tank 5 also increases. However, the amount of change in the liquid level of the molten glass Gm is different in the melting furnace 2 and the transfer device 3.

[0099] In the determination process S8, based on the result of the grasping process S6, the increase or decrease of the glass raw material Ga on the molten glass Gm in the melting furnace 2 is determined, and based on the result of the measuring process S7, the rise or fall of the liquid level of the molten glass Gm in the clarification tank 5 is determined. And, based on these determination results, the input conditions of the input process S1 are appropriately changed. It should be noted that in the determination process S8, the determination criteria for determining the increase or decrease of the glass raw material Ga on the molten glass Gm and the determination criteria for determining the rise or fall of the liquid level of the molten glass Gm in the clarification tank 5 can be appropriately changed. In addition, the increase or decrease of the glass raw material Ga on the molten glass Gm and the up and down movement of the liquid level of the molten glass Gm are easy to occur when, for example, the blank of the molten glass Gm is replaced, the discharge amount of the molten glass Gm in the discharge process is changed, the variety of various raw materials contained in the glass raw material Ga is changed, and the content of cullet in the glass raw material Ga is changed.

[0100] like Figure 8 As shown, the input process S1 includes a first input process S11, a second input process S12 and a third input process S13. Fig. 9As shown, the first input step S11, the second input step S12, and the third input step S13 have different input conditions for the glass raw material Ga. The first input step S11, the second input step S12, and the third input step S13 are sequentially executed based on the determination result of the determination step S8 (the first input step S11 → the second input step S12 → the third input step S13). It should be noted that the second input step S12 and the third input step S13 are not executed during the normal execution of the first input step S11.

[0101] In the charging step S1 , first, a first charging step S11 is performed in which the glass-making raw material Ga is continuously charged into the melting furnace 2 at a first average charging speed V1 .

[0102] The first average input speed V1 can be defined by a value [kg / h] obtained by dividing the total input amount (total input amount) of the glass raw material Ga in the first input step S11 by the execution time of the first input step S11. In simple terms, the first average input speed V1 can be obtained, for example, by the input amount [kg / h] of the glass raw material Ga per hour in the first input step S11.

[0103] Next, during the execution of the first charging step S11, when it is determined in the determination step S8 that the glass raw material Ga on the molten glass Gm increases and the liquid level of the molten glass Gm decreases, the first charging step S11 is stopped, and a second charging step S12 (see FIG. 1 ) in which the glass raw material Ga is charged at a second average charging speed V2 slower than the first average charging speed V1 is executed. Fig. 9 ). If the second input step S12 is performed in this way, the temperature in the melting furnace 2 (for example, the top temperature in the melting furnace, the atmosphere temperature, and the molten glass temperature) rises, and the heating and melting of the glass raw material Ga on the molten glass Gm is promoted. As a result, the state of increasing glass raw material Ga on the molten glass Gm is alleviated, and the liquid level of the molten glass Gm can be suppressed from further decreasing. Therefore, even if the glass raw material Ga on the molten glass Gm increases, the blank is prevented from being exhausted, and the production of plate glass can be reliably continued.

[0104] The second average input speed V2 can be defined by a value [kg / h] obtained by dividing the total input amount (total input amount) of the glass raw material Ga in the second input step S12 by the execution time of the second input step S12. In simple terms, the second average input speed V2 can be obtained, for example, by the input amount [kg / h] of the glass raw material Ga per hour in the second input step S12.

[0105] The second average charging speed V2 is preferably 0.5 to 0.95 times, and more preferably 0.7 to 0.9 times, the first average charging speed V1. The execution time of the second charging step S12 is preferably, for example, 0.5 to 24 hours.

[0106] In the determination step S8, for example, Figure 5 As shown in FIG. 1 , when the height of the pile Gb exceeds the top height H1 of the inlet 14, it is determined that the glass raw material Ga on the molten glass Gm has increased (the first execution condition of the second input step S12). In other words, in the determination step S8, for example, Figure 2 As shown, when the height of the pile Gb is equal to or less than the top height H1 of the inlet 14, it is determined that the glass feedstock Ga on the molten glass Gm has not increased.

[0107] Alternatively, in the determination step S8, for example, when the height T1 (mm) of the pile Gb grasped by the grasping step becomes greater than the first threshold, it may be determined that the glass raw material Ga on the molten glass Gm has increased. The first threshold can be set, for example, to 1.5 to 2.0 times the height T0 (mm) of the pile Gb when stable. Here, the height T0 and T1 of the pile Gb are the distances from the liquid surface of the molten glass Gm in the melting furnace 2 to the top of the pile Gb.

[0108] In the determination step S8, for example, Figure 7 As shown in FIG. 1 , when the liquid level of the molten glass Gm in the clarification tank 5 drops below the second threshold value H2, it is determined that the liquid level of the molten glass Gm has dropped (the second execution condition of the second input step S12). In other words, in the determination step S8, for example, Figure 6 As shown in FIG. 1 , when the liquid level of the molten glass Gm in the clarification tank 5 exceeds the second threshold value H2, it is determined that the liquid level of the molten glass Gm has not decreased. The second threshold value is preferably set to 80 to 95% of the liquid level when the clarification tank 5 is stable. Figure 6 In the figure, no gas phase space is formed in the clarification tank 5 but the molten glass Gm is filled therein. However, the gas phase space may be formed in the clarification tank 5 when the clarification tank 5 is stable.

[0109] The second input step S12 is executed when both the first execution condition and the second execution condition mentioned above are satisfied. Fig.10 As shown, it is preferred that in the second input step S12, while maintaining the state of the liquid level of the molten glass Gm being lowered, the glass raw material Ga on the molten glass Gm is reduced to reduce the material pile Gb. Thus, while more reliably preventing the occurrence of blank exhaustion, the temperature in the melting furnace 2 is reliably increased, thereby further promoting the heating and melting of the glass raw material Ga on the melting furnace 2.

[0110] Thereafter, during the execution of the second charging step S12, if it is determined in the determination step S8 that the glass raw material Ga on the molten glass Gm is reduced, the second charging step S12 is stopped, and a third charging step S13 (see FIG. 1 ) is executed in which the glass raw material Ga is charged while gradually increasing the charging speed from the second charging step S12. Fig. 9 ). Thus, it is possible to raise the liquid level of the molten glass Gm and restore it to its original state while suppressing a decrease in the temperature in the melting furnace 2.

[0111] In the determination step S8, for example, Fig.10 As shown, when the height of the pile Gb becomes equal to or less than the top height H1 of the inlet 14 , it may be determined that the glass feedstock Ga on the molten glass Gm has decreased (execution condition of the third input step S13 ).

[0112] Alternatively, in the determination step S8, for example, when the height T1 (mm) of the pile Gb grasped in the grasping step becomes less than the third threshold, it can be determined that the glass raw material Ga on the molten glass Gm is reduced. The third threshold can be set to, for example, 0.8 to 1.2 times the height T0 (mm) of the pile Gb when stable, preferably smaller than the first threshold. Here, the height T0 and T1 of the pile Gb are the distances from the liquid surface of the molten glass Gm in the melting furnace 2 to the top of the pile Gb.

[0113] Furthermore, during the execution of the third input step S13, if it is determined in the determination step S8 that the liquid level of the molten glass Gm has risen, the third input step S13 is stopped, and the first input step S11 is started again (see Fig. 9 ). Thus, the production of plate glass can be stabilized. The execution time of the third input step S13 is preferably 0.5 to 8 hours, for example.

[0114] In the determination step S8, for example, when the liquid level of the molten glass Gm in the clarification tank 5 is above the fourth threshold value, it is determined that the liquid level of the molten glass Gm has risen (the execution condition (restart condition) of the first input step S11). The fourth threshold value can be set to 90 to 100% of the liquid level when stable, and is preferably greater than the second threshold value.

[0115] Here, in Fig. 9 , the figure shows a case where the feeding speeds in the first feeding step S11 and the second feeding step S12 are constant, but the feeding speeds at any moment are not particularly limited as long as the first average feeding speed V1>the second average feeding speed V2 is satisfied.

[0116] For example, Fig.11As shown, the first feeding process S11 may also include: a high-speed process S11a, in which the screw of the feeding machine 15 rotates at a high speed and the feeding speed of the glass raw material Ga is set to a relatively fast feeding speed V1a; and a low-speed process S11b, in which the screw of the feeding machine 15 rotates at a low speed and the feeding speed of the glass raw material Ga is set to a relatively slow feeding speed V1b.

[0117] Likewise, Fig.12 As shown, the second feeding process S12 may also include: a high-speed process S12a, in which the screw of the feeding machine 15 rotates at a high speed and the feeding speed of the glass raw material Ga is set to a relatively fast feeding speed V2a; and a low-speed process S12b, in which the screw of the feeding machine 15 rotates at a low speed and the feeding speed of the glass raw material Ga is set to a relatively slow feeding speed V2b.

[0118] The low speed step S12b of the second feeding step S12 may also be a stop step of stopping the rotation of the screw of the feeding machine 15 and setting the feeding speed V2b to zero. In this case, the glass raw material Ga is intermittently fed in the second feeding step S12. Thus, even if a feeding machine that cannot finely adjust the feeding speed (rotation speed of the screw) is used, the second feeding step S12 can be reliably performed.

[0119] When the second feeding step S12 includes the stopping step S12 b , the feeding speed V2 a may be the same as the feeding speed V1 a or the feeding speed V1 b of the first feeding step S11 .

[0120] The execution time of each stop step S12b is preferably within 2 hours. This is because if the execution time of the stop step S12b is too long, the glass feedstock Ga inside the input machine 15 may solidify or the liquid level of the molten glass Gm may drop.

[0121] exist Fig. 9 In the figure, the feeding speed of the third feeding process S13 is gradually increased and only the feeding speed of the final stage of the third feeding process S13 is faster than the feeding speed of the first feeding process S11, but it is not limited to this. Fig.13 As shown, the total input speed from the initial stage to the final stage of the third input step S13 can also be made faster than the input speed of the first input step S11. In this case, the glass raw material Ga on the molten glass Gm is likely to increase in the third input step S13, so the execution time of the third input step S13 needs to be shorter than the case where the input speed is gradually increased.

[0122] (Second embodiment)

[0123] like Fig.14As shown, in the manufacturing apparatus and manufacturing method of the glass article of the second embodiment, the position and method of measuring the liquid level of the molten glass are different from those of the first embodiment.

[0124] In the present embodiment, in the measuring step S7, the liquid level of the molten glass Gm in the melting furnace 2 is measured. In the judging step S8, based on the result of the grasping step S6, the increase or decrease of the glass raw material Ga on the molten glass Gm in the melting furnace 2 is judged, and based on the result of the measuring step S7, the increase or decrease of the liquid level of the molten glass Gm in the melting furnace 2 is judged. And, based on these judgment results, appropriate changes are applied to the input step S1.

[0125] In the measuring step S7, for example, a bubble-type level gauge 21 is used to measure the liquid level of the molten glass Gm in the melting furnace 2. Specifically, the level gauge 21 supplies gas to the molten glass Gm through the pipe 22 to generate bubbles B from the front end of the pipe 22, and measures the liquid level of the molten glass Gm based on the pressure (back pressure) in the pipe 22 in a state where the bubbles B are generated.

[0126] In the present embodiment, the pipe 22 is guided into the melting furnace 2 through a through hole X2 provided on a wall portion (e.g., a side wall) of the melting furnace 2 at a position higher than the liquid level Gma of the molten glass Gm, and its front end portion is immersed in the molten glass Gm. In this way, the pipe 22 can be extracted from the through hole X2, so the maintenance operation of the level gauge 21 becomes easy. It should be noted that, although the maintenance operation of the level gauge 21 becomes difficult, the pipe 22 can also be guided into the melting furnace 2 through a wall portion (e.g., a bottom wall 2c, etc.) of the melting furnace 2 at a position lower than the liquid level Gma of the molten glass Gm.

[0127] The present invention is not limited to the configuration of the above-described embodiment, nor is it limited to the above-described effects. The present invention can be modified in various ways without departing from the gist of the present invention.

[0128] In the above-mentioned embodiment, the case where the liquid level of the molten glass Gm in the clarification tank 5 is measured and the case where the liquid level of the molten glass Gm in the melting furnace 2 is measured as the measuring step S7 is described, but in the measuring step S7, it is sufficient to measure the liquid level of the molten glass Gm in at least one of the melting furnace 2 and the transfer device 3. That is, in the measuring step S7, the liquid level of the molten glass Gm may be measured in both the melting furnace 2 and the transfer device 3. In addition, when the liquid level of the molten glass Gm in the transfer device 3 is measured, the liquid level of the molten glass Gm in the portion other than the clarification tank 5 included in the transfer device 3 may be measured.

[0129] In the above-mentioned embodiment, the method for measuring the liquid level of the molten glass Gm in the measuring step S7 is not particularly limited. For example, the liquid level of the molten glass Gm in the melting furnace 2 may be measured using the level gauge 18 described in the above-mentioned first embodiment. In addition, the liquid level of the molten glass Gm in the clarification tank 5 may be measured using the bubble level gauge 21 described in the above-mentioned second embodiment.

[0130] In the above-mentioned embodiment, the case where the height of the pile Gb is measured in the grasping step S6 is described, but the method of grasping the state of the glass raw material Ga on the molten glass Gm in the melting furnace 2 is not limited to this. For example, the cross-sectional area and volume of the pile Gb may be measured in the grasping step S6. In addition, when the material layer does not include the pile Gb, the thickness of the material layer and the area of ​​the molten glass Gm covered by the material layer may be measured.

[0131] In the above-mentioned embodiment, the case where the state of the glass raw material Ga on the molten glass Gm in the melting furnace 2 is directly grasped based on the height of the pile Gb in the grasping step S6 is described, but the state of the glass raw material Ga on the molten glass Gm in the melting furnace 2 may be grasped indirectly. For example, in the grasping step S6, in order to indirectly grasp the state of the glass raw material Ga on the molten glass Gm in the melting furnace 2, the temperature in the melting furnace 2 (for example, the top temperature of the melting furnace 2) may be measured. In this case, for example, in the determination step S8, when the temperature in the melting furnace 2 drops below a predetermined temperature, it may be determined that the glass raw material Ga on the molten glass Gm in the melting furnace 2 increases. Specifically, when the top temperature of the melting furnace 2 becomes 400° C. or less and the liquid level of the molten glass Gm in at least one of the melting furnace 2 and the transfer device 3 drops below a predetermined level, the first input step S11 may be stopped and the second input step S12 may be performed.

[0132] In the above-mentioned embodiment, a glass plate and a glass roll are exemplified as the glass article, but the glass article can be, for example, a glass ball, a glass tube, a glass block, a glass fiber, etc., and may be in any shape other than these.

Claims

1. A method for manufacturing a glass article, comprising: A first charging step of continuously charging glass raw materials into the melting furnace at a first average charging speed; A melting step of heating and melting the glass raw materials put into the melting furnace to generate molten glass; a discharging step of discharging the molten glass generated in the melting furnace to the outside of the melting furnace; A transferring step of transferring the molten glass discharged out of the melting furnace by using a transferring device; as well as forming a glass article from the molten glass transferred by the transfer device, The method for manufacturing the glass article is characterized by comprising: A grasping step of grasping a state of the glass raw material on the molten glass in the melting furnace; a measuring step of measuring a liquid level of the molten glass in at least one of the melting furnace and the transfer device; and a judging step of judging the state of the glass raw material on the molten glass and the liquid level of the molten glass based on the results of the grasping step and the measuring step, When it is determined in the determination step that the glass raw material on the molten glass has increased and the liquid level of the molten glass has decreased, the first feeding step is stopped and a second feeding step of feeding the glass raw material at a second average feeding speed slower than the first average feeding speed is performed.

2. The method for manufacturing a glass article according to claim 1, wherein: In the second charging step, the glass raw material is charged intermittently.

3. The method for manufacturing a glass article according to claim 1 or 2, wherein: In the measuring step, the liquid level of the molten glass in the transfer device is measured.

4. The method for manufacturing a glass article according to claim 3, wherein: In the determining step, when the liquid level of the molten glass in the transfer device drops below a threshold value, it is determined that the liquid level of the molten glass has dropped, The threshold value is 80-95% of the liquid level at steady state.

5. The method for manufacturing a glass article according to claim 1 or 2, wherein: In the second charging step, the glass raw material on the molten glass is reduced while the liquid surface level of the molten glass is maintained in a lowered state.

6. The method for manufacturing a glass article according to claim 1 or 2, wherein: When it is determined in the determination step that the glass raw material on the molten glass has decreased due to the second feeding step, the second feeding step is stopped, and a third feeding step of feeding the glass raw material while gradually increasing the feeding speed from the second feeding step is performed.

7. The method for manufacturing a glass article according to claim 6, wherein: When it is determined in the determining step that the liquid surface level of the molten glass has risen due to the third charging step, the third charging step is stopped and the first charging step is restarted.

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