Method for manufacturing glass articles

Abstract

A method for manufacturing glass articles based on an overflow down-draw method includes: a heating step for heating a forming body (3) arranged in a forming furnace (2); and a forming step for supplying molten glass (Gm) to the heated forming body (3) and forming a glass ribbon (Gr) from the molten glass (Gm). In the heating step, a furnace heater (15) arranged in the forming furnace (2) is used to heat the lower part of the forming body (3) including the lower end part (3a).

Description

Technical Field

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

[0002] As a method for manufacturing glass products such as glass sheets, an overflow down-draw method is sometimes used. In this method, a forming device is provided with a roughly wedge-shaped forming body in a forming furnace. After the molten glass supplied to the forming body overflows from the groove formed on the top of the forming body, it merges at the lower end along the two outer sides of the forming body. Thus, a ribbon-shaped glass ribbon is continuously formed from the molten glass. According to this method, the front and back sides of the formed glass ribbon do not contact the forming body during the forming process, so there is an advantage that a smooth glass ribbon without damage on the front and back sides can be formed (for example, refer to Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-214349 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the case of a method for manufacturing glass products using an overflow down-draw method, the molten glass during forming is at a high temperature, so before starting the process (before supplying molten glass to the forming body), a heating step is performed to raise the temperature of the periphery of the forming body and the temperature of the forming body.

[0008] However, in this temperature-raising process, the formed body is easily damaged by the thermal shock caused by the temperature change of the formed body. In particular, the lower part of the formed body has a smaller cross-sectional area (thickness) due to its roughly wedge-shaped shape, so the heat capacity is small and it is easy to cool. In addition, the lower part of the formed body is prone to tensile stress due to the deflection caused by its own weight. Therefore, when the temperature of the lower part of the formed body is reduced due to the rising airflow generated in the forming furnace, the formed body is easily damaged starting from the lower part of the formed body.

[0009] The present invention suppresses breakage of a molded body used in an overflow down-draw method in a temperature raising step.

[0010] Solutions to Solve Problems

[0011] The present invention made in order to solve the above-mentioned problems is a method for manufacturing glass products using an overflow down-draw method. The method for manufacturing glass products is characterized in that it includes: a heating step of heating a forming body arranged in a forming furnace; and a forming step of supplying molten glass to the heated forming body and forming a glass ribbon from the molten glass, and in the heating step, the lower part of the forming body is heated using an in-furnace heater arranged in the forming furnace.

[0012] If the furnace heater is arranged in the forming furnace in this way, the heater can be arranged near the lower part of the formed body compared to the case where the furnace heater is arranged outside the forming furnace. As a result, even if an upward airflow or the like is generated in the forming furnace, the temperature of the lower part of the formed body can be stabilized by the furnace heater, thereby reducing damage such as cracking of the formed body.

[0013] In the above-mentioned configuration, it is preferable that, after the molten glass is supplied to the forming body, the heating of the lower portion of the forming body by the heater in the furnace is reduced or stopped.

[0014] That is, when molten glass is supplied to the forming body, the forming body is covered with high-temperature molten glass, so it is difficult to cause the temperature of the lower part of the forming body to drop. On the other hand, when the lower part of the forming body is heated by the furnace heater in a state where the forming body is covered with high-temperature molten glass, the molten glass and / or the glass ribbon are overheated, and it may be difficult to stably form the glass ribbon. Therefore, after the molten glass is supplied to the forming body, it is preferable to reduce or stop the heating of the furnace heater as in the above-mentioned structure.

[0015] In the above-described configuration, it is preferable that, after the molten glass is supplied to the forming body, the in-furnace heater is retracted from a position where the lower portion of the forming body is heated.

[0016] Thus, the heating of the lower part of the forming body by the furnace heater can be reduced or stopped simply and reliably. In addition, the furnace heater is separated from the molten glass and the glass ribbon, so the furnace heater does not become an obstacle in the production process.

[0017] In the above configuration, the furnace heaters are preferably arranged in pairs to sandwich both outer side surfaces of the lower portion of the forming body in the thickness direction of the glass ribbon or a glass ribbon passage portion below the lower portion of the forming body from both sides in the thickness direction.

[0018] In this way, the lower portion of the formed body can be heated uniformly from both sides.

[0019] In the above-mentioned configuration, it is preferable that the in-furnace heater is arranged in the forming furnace through an opening for a conveying roller of the glass ribbon provided in a side wall portion of the forming furnace.

[0020] In this manner, the furnace heater can be arranged without providing a new opening in the forming furnace, thereby suppressing an increase in equipment cost.

[0021] In the above-described configuration, it is preferable that a thermometer for measuring the temperature of the lower portion of the formed body is disposed in the forming furnace in the temperature raising step.

[0022] This makes it easier to manage the temperature of the lower portion of the molded body, and it is possible to further reduce damage to the molded body.

[0023] In the above-mentioned structure, outside the forming furnace, a first external furnace heater for heating the upper part of the formed body is arranged at a position corresponding to the upper part of the side wall of the forming furnace, a second external furnace heater for heating the lower part of the formed body is arranged at a position corresponding to the lower part of the side wall of the forming furnace, and a third external furnace heater for heating the upper part of the formed body is arranged at a position corresponding to the top of the forming furnace. In the heating process, the first external furnace heater, the second external furnace heater and the third external furnace heater are used to further heat the formed body.

[0024] By using the external furnace heater in this manner, the temperature of the compact can be increased in a state where a desired temperature distribution is given to the compact.

[0025] Effects of the Invention

[0026] According to the present invention, it is possible to suppress the molded body used in the overflow down-draw method from being damaged in the temperature raising step. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a side view of the manufacturing apparatus of the glass article of the first embodiment, and shows the state of the production process.

[0028] Figure 2 It is a front view of the manufacturing apparatus of the glass article of the first embodiment, and shows the state of the production process.

[0029] Figure 3 It is a side view of the periphery of the forming furnace of the first embodiment, and shows the state of the temperature raising process.

[0030] Figure 4 It is a front view of the periphery of the forming furnace of the first embodiment, and shows the state of the temperature rising process.

[0031] Figure 5 It is a perspective view of the periphery of the side wall portion of the forming furnace of the first embodiment, and shows the state of the production process.

[0032] Figure 6 It is a perspective view of the periphery of the side wall portion of the forming furnace of the first embodiment, and shows the state of the temperature rising step.

[0033] Figure 7 This is a side view of the periphery of a forming furnace for explaining the step of transition from a temperature raising step to a production step in the first embodiment.

[0034] Figure 8 This is a side view of the periphery of a forming furnace for explaining the step of transition from a temperature raising step to a production step in the first embodiment.

[0035] Fig. 9 This is a side view of the periphery of a forming furnace for explaining the step of transition from a temperature raising step to a production step in the first embodiment.

[0036] Fig.10 It is a side view of the periphery of the forming furnace of the second embodiment, and shows the state of the temperature rising process.

[0037] Fig.11 It is a side view of the periphery of the forming furnace of the third embodiment, and shows the state of the temperature raising process. DETAILED DESCRIPTION

[0038] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that, in the orthogonal coordinate system composed of XYZ shown in the figure, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction. In addition, the direction corresponding to the width direction of the formed glass ribbon Gr is referred to as the width direction X, and the direction corresponding to the thickness direction of the formed glass ribbon Gr is referred to as the thickness direction Y. Moreover, the same reference numerals are marked on 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 described previously can be applied to the other parts of the structure. In addition, not only the combination of the structures explicitly described 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.

[0039] (First Embodiment)

[0040] like Figure 1 to Figure 4 As shown, the manufacturing method of the glass article of the first embodiment is a method of manufacturing a glass sheet G as a glass article by using a manufacturing apparatus 1 for glass articles and an overflow down-draw method. The manufacturing method includes: a heating step ( Figure 3 as well as Figure 4 ), heating the formed body 3 disposed in the forming furnace 2; and production process ( Figure 1 as well as Figure 2 ), including a forming step of supplying molten glass Gm to a heated forming body 3 and forming a glass ribbon Gr from the molten glass Gm.

[0041] The production process is implemented after the heating process. In this embodiment, the production process includes a forming process, an annealing process, a cooling process, and a cutting process.

[0042] Hereinafter, the state of the manufacturing apparatus 1 in the production process (molding process) will be described first, and then the state of the manufacturing apparatus 1 in the temperature increase process will be described. Thereafter, the transition procedure from the temperature increase process to the production process (molding process) will be described.

[0043] like Figure 1 as well as Figure 2 As shown, a manufacturing device 1 in a production process includes: a forming furnace 2; an annealing furnace 4, which is located below the forming furnace 2; a cooling chamber 5, which is located below the annealing furnace 4; and a cutting chamber 6, which is located below the cooling chamber 5. The forming furnace 2 and the annealing furnace 4, the annealing furnace 4 and the cooling chamber 5, and the cooling chamber 5 and the cutting chamber 6 are respectively separated by partition members (such as the floor surface of a building) F1, F2, and F3 having openings (such as slits) for passing the glass ribbon Gr.

[0044] like Figure 1 as well as Figure 2 As shown, the forming furnace 2 is an area for forming a glass ribbon Gr from molten glass Gm by an overflow down-draw method. Inside the forming furnace 2, a forming body 3 for forming the glass ribbon Gr from the molten glass Gm and a first conveying roller 7 for cooling both ends of the glass ribbon Gr formed by the forming body 3 in the width direction X are arranged.

[0045] The formed body 3 is formed of a refractory material that is elongated along the width direction X. Examples of the refractory material include zircon, zirconia, alumina, magnesia, and xenotime.

[0046] A groove (overflow groove) 8 formed along the width direction X is provided at the top of the forming body 3. A supply pipe 9 is connected to one end side of the groove 8 in the width direction X. The molten glass Gm is supplied into the groove 8 through the supply pipe 9. The supply method of the molten glass Gm is not limited thereto. For example, the molten glass Gm may be supplied from both end sides of the groove 8 in the width direction X, or may be supplied from the top of the groove 8.

[0047] The formed body 3 is symmetrical in the thickness direction Y. The two outer side surfaces 10 of the formed body 3 in the thickness direction Y respectively include: a vertical surface 11, which is a plane along the vertical direction; and an inclined surface 12, which is connected to the bottom of the vertical surface 11 and is a plane inclined relative to the vertical direction. Each vertical surface 11 is a plane parallel to each other. Each inclined surface 12 is a plane inclined in a manner that approaches each other in the thickness direction Y as it tends to go downward. That is, the formed body 3 is formed by forming each inclined surface 12, so that when viewed from the width direction X, it is a wedge shape that tends to go downward and becomes thinner at the front end, and the corner where each inclined surface 12 intersects forms the lower end 3a of the formed body 3. It should be noted that the vertical surface 11 can be changed in shape to an inclined surface, a curved surface, etc., or it can be omitted.

[0048] The first conveying roller 7 is configured as a pair of rollers that clamp the ends of the glass ribbon Gr in the width direction X in the thickness direction Y just below the forming body 3. The first conveying roller 7 is a cantilever type roller, and is always cooled internally during the forming process. The first conveying roller 7 is also called a cooling roller or an edge roller. It should be noted that the first conveying roller 7 can be provided with multiple sections (for example, two sections) in the up and down direction Z. For example, in the case of two sections, it is preferred that the first conveying roller 7 in the upper section is provided as a driving roller, and the first conveying roller 7 in the lower section is provided as a free roller.

[0049] like Figure 1 as well as Figure 2 As shown, the annealing furnace 4 is an area for reducing the warping and internal strain of the glass ribbon Gr. A second conveying roller 13 is arranged inside the annealing furnace 4. The second conveying roller 13 is also called an annealing roller. The second conveying roller 13 is configured as a roller pair that clamps each end of the glass ribbon Gr in the width direction X in the thickness direction Y. The second conveying roller 13 can also be a double-supported type roller configured in a manner that spans the entire area of ​​the glass ribbon Gr in the width direction X, but in this embodiment, it is a cantilever type roller. The second conveying roller 13 is provided with multiple sections in the up and down direction Z.

[0050] like Figure 1 as well as Figure 2 As shown in FIG. 1 , the cooling chamber 5 is an area for cooling the glass ribbon Gr to near room temperature. A third conveying roller 14 is arranged inside the cooling chamber 5. The third conveying roller 14 is configured as a roller pair that clamps each end of the glass ribbon Gr in the width direction X in the thickness direction Y. The third conveying roller 14 may also be a double-supported type roller arranged in a manner spanning the entire area of ​​the glass ribbon Gr in the width direction X, but in this embodiment, it is a cantilever type roller. The third conveying roller 14 is provided in multiple stages in the up-down direction Z.

[0051] Here, the second conveying roller 13 and / or the third conveying roller 14 may include rollers that do not clamp the two end portions of the glass ribbon Gr in the width direction X. That is, the opposing interval of the roller pair constituting the second conveying roller 13 and / or the third conveying roller 14 may be set to be larger than the thickness of the two end portions of the glass ribbon Gr in the width direction X, so that the glass ribbon Gr passes between the roller pairs. It should be noted that in the present embodiment, the two end portions of the glass ribbon Gr in the width direction X obtained by the manufacturing device 1 include ear portions having a thickness greater than that of the central portion in the width direction X due to the influence of shrinkage in the forming process and the like.

[0052] like Figure 1 as well as Figure 2 As shown, the cutting chamber 6 is an area for cutting the glass ribbon Gr into a predetermined size and obtaining a glass plate G as a glass article. A cutting device (not shown) for cutting the glass ribbon Gr is arranged inside the cutting chamber 6. In the present embodiment, the cutting method of the glass ribbon Gr by the cutting device is a scoring cutting method in which the glass ribbon Gr is broken along the scoring line after the scoring line is formed on the glass ribbon Gr, but it is not limited to this. The cutting method of the cutting device may also be, for example, laser cutting, laser melting, etc.

[0053] The glass plate G is a glass original plate (mother glass plate) from which one or more product glass plates are obtained. The thickness of the product glass plate is, for example, 0.2 mm to 10 mm, and the size of the product glass plate is, for example, 700 mm×700 mm to 3500 mm×3500 mm. The product glass plate is used, for example, as a substrate or cover glass of a display. It should be noted that the substrate or cover glass of a display is not limited to a flat plate, but may also be a curved plate.

[0054] like Figure 1 as well as Figure 2 As shown, in the production process using the above-mentioned manufacturing device 1, first, in the forming furnace 2, molten glass Gm is supplied to the groove 8 of the forming body 3, so that the molten glass Gm overflowing from the groove 8 to both sides flows down along the vertical surface 11 and the inclined surface 12 and merges again at the lower end 3a. Thus, a ribbon-shaped glass ribbon Gr is continuously formed from the molten glass Gm (forming process). Next, in the annealing furnace 4, the glass ribbon Gr is annealed (annealing process), and in the cooling chamber 5, the glass ribbon Gr is cooled to near room temperature (cooling process). Thereafter, in the cutting chamber 6, the glass ribbon Gr is cut to obtain a glass plate G (cutting process). The cutting process includes: a first cutting process, in which the glass ribbon Gr is cut along the width direction X according to each specified length to obtain a glass plate G; and a second cutting process, in which the ears at both ends of the glass plate G in the width direction X are cut and removed. It should be noted that in the production process, the post-forming process is not particularly limited. For example, the production process may further include a cleaning process, an inspection process, a packaging process, and the like.

[0055] like Figure 3 as well as Figure 4 As shown, the manufacturing apparatus 1 of the glass article in the heating process is provided with a furnace heater 15 for heating the lower part of the forming body 3 and a furnace thermometer 16 for measuring the temperature of the lower part of the forming body 3 in the forming furnace 2. Here, the lower part of the forming body 3 means, for example, a part corresponding to the inclined surface part 12 of the forming body 3.

[0056] The furnace heater 15 is arranged in pairs so as to sandwich the passage portion of the glass ribbon Gr below the lower end portion 3a of the forming body 3 from both sides in the thickness direction Y. In the present embodiment, the furnace heater 15 is composed of a pair of rod-shaped heaters (e.g., sheath heaters) extending along the width direction X and facing each other in the thickness direction Y. In detail, the furnace heater 15 is cross-sectionally arranged along the width direction X inside the forming furnace 2, and its two ends penetrate the side wall portion 2a of the forming furnace 2 and are held outside the forming furnace 2. It should be noted that a plurality of furnace heaters 15 may be arranged in pairs in the vertical direction. In addition, the holding method of the furnace heater 15 is not limited to a method of holding both ends outside the furnace (double support holding), for example, it may also be a method of holding only one end outside the furnace (cantilever holding).

[0057] The width dimension W1 of the furnace heater 15 in the forming furnace 2 is arranged to be wider than the width dimension W2 of the lower end portion 3a of the formed body 3. That is, the furnace heater 15 heats the entire width of the lower end portion 3a of the formed body 3.

[0058] Here, in Figure 3 The configuration position of the furnace heater 15 is preferably within the range of a circle C centered on the lower end portion 3a of the formed body 3 when viewed from the side. The diameter D of the circle C is preferably, for example, 50 mm to 300 mm, more preferably 100 mm to 200 mm. In this way, the lower portion of the formed body 3 including the lower end portion 3a can be efficiently heated.

[0059] The furnace thermometer 16 (e.g., a thermocouple) is disposed just below the lower end portion 3a of the forming body 3, that is, the passage portion of the glass ribbon Gr. The position of the furnace thermometer 16 is not particularly limited as long as the temperature of the lower portion of the forming body 3 can be measured. For example, the furnace thermometer 16 may be disposed in contact with the lower portion of the forming body 3, or a plurality of furnace thermometers 16 may be disposed.

[0060] In the present embodiment, the manufacturing apparatus 1 of the glass article in the temperature raising process is provided with: a first furnace external heater 17 for heating the upper part of the formed body 3; a second furnace external heater 18 for heating the lower part of the formed body 3; and a third furnace external heater 19 for heating the upper part of the formed body 3 outside the forming furnace 2. The first furnace external heater 17 is arranged at a position corresponding to the upper part of the side wall portion 2a of the forming furnace 2. The second furnace external heater 18 is arranged at a position corresponding to the lower part of the side wall portion 2a of the forming furnace 2. The third furnace external heater 19 is arranged at a position corresponding to the top 2b of the forming furnace 2.

[0061] In addition, the manufacturing device 1 of the glass article in the heating process is provided outside the forming furnace 2 with: a first furnace-outside thermometer 20 for measuring the temperature of the side wall portion 2a at a position corresponding to the first furnace-outside heater 17; a second furnace-outside thermometer 21 for measuring the temperature of the side wall portion 2a at a position corresponding to the second furnace-outside heater 18; and a third furnace-outside thermometer 22 for measuring the temperature of the top portion 2b at a position corresponding to the third furnace-outside heater 19. It should be noted that the furnace-outside heaters 17, 18, and 19 may be divided into a plurality of parts in the width direction X and may be composed of a plurality of local heaters. In this case, the furnace-outside thermometers 20, 21, and 22 may be provided for each local heater.

[0062] like Figure 5 As shown in FIG. 1 , in the production process, the first conveying roller 7 is inserted from outside the forming furnace 2 into the furnace through the opening 23 provided in the side wall 2a of the forming furnace 2. The gap between the opening 23 and the shaft 7a of the first conveying roller 7 is sealed by, for example, a first sealing member 24 made of refractory fiber. One end of the shaft 7a is held by a bearing (not shown) arranged outside the forming furnace 2. On the other hand, as shown in FIG. Figure 6 As shown, in the heating process, the furnace heater 15 is arranged in the furnace from outside the forming furnace 2 through the opening 23 for the first conveying roller 7. The gap between the opening 23 and the furnace heater 15 is sealed by a second sealing member 25 made of refractory fiber, for example. The furnace heater 15 and one end of the furnace thermometer 16 are held by a member arranged outside the forming furnace 2.

[0063] like Figure 3 as well as Figure 4 As shown, in the temperature raising step using the manufacturing apparatus 1 described above, the lower portion of the formed body 3 is heated by the furnace heater 15 disposed in the forming furnace 2. Thus, even when an upward airflow or the like is generated in the forming furnace 2, the temperature of the lower portion of the formed body 3 can be stabilized by the furnace heater 15 disposed near the lower portion of the formed body 3, thereby reducing damage such as cracking of the formed body 3 caused by thermal shock.

[0064] In addition, in the temperature raising process of the present embodiment, the formed body 3 is also heated by the furnace external heaters 17, 18, and 19 arranged outside the forming furnace 2. Thus, the temperature distribution in the forming furnace 2 can be appropriately adjusted. The temperature distribution in the forming furnace 2 is not particularly limited. For example, in the forming furnace 2, the temperature near the top 2b can be set higher than the temperature near the lower part of the formed body 3, the temperature near the top 2b can be set lower than the temperature near the lower part of the formed body 3, and the temperature near the top 2b can be set the same as the temperature near the lower part of the formed body 3.

[0065] The heating temperatures of the in-furnace heater 15 and / or the external-furnace heaters 17 , 18 , 19 are adjusted based on the temperatures measured by the in-furnace thermometer 16 and / or the external-furnace thermometers 20 , 21 , 22 .

[0066] like Figure 7 to Figure 9 As shown in FIG. 1 , when the molded body 3 is heated to a predetermined temperature in the heating step, the heating step is transferred to the production step. When transferring from the heating step to the production step, first, as shown in FIG. Figure 7 As shown in FIG. 1 , the furnace heater 15 and the furnace external heaters 17, 18, 19 are kept heating the formed body 3, and the furnace thermometer 16 is removed from the furnace. Figure 8 As shown in FIG. 1 , the furnace heater 15 and the furnace heaters 17, 18, and 19 are kept heating the forming body 3, and the molten glass Gm is supplied to the groove 8 of the forming body 3, and the molten glass Gm overflowing from the groove 8 covers the outer side surfaces 10 of the forming body 3. After the outer side surfaces 10 of the forming body 3 (particularly the lower end portion 3a of the forming body 3) are covered with the molten glass Gm, as shown in FIG. Fig. 9 As shown, the furnace heaters 17, 18, 19 are kept heating the formed body 3, and the furnace heater 15 is retracted from the position heating the lower part of the formed body 3. In this embodiment, the furnace heater 15 is removed from the furnace through the opening 23 of the forming furnace 2.

[0067] The production process including the forming process starts at the stage where the predetermined preparation process such as placing the first conveying roller 7 at a predetermined position in the furnace through the opening 23 of the forming furnace 2 is completed, so as to manufacture the glass sheet G to be the product. It should be noted that in the production process, it is also preferable to manage the temperature distribution in the forming furnace 2 using the external heaters 17, 18, 19.

[0068] When the molten glass Gm is supplied to the forming body 3, the forming body 3 is covered with the high-temperature molten glass Gm, so that the temperature of the lower part of the forming body 3 is not easily reduced. On the other hand, in a state where the forming body 3 is covered with the high-temperature molten glass Gm, when the lower part of the forming body 3 is heated by the furnace heater 15, the molten glass Gm and / or the glass ribbon Gr are excessively heated, and it may be difficult to stably form the glass ribbon Gr. Therefore, in the production process (forming process), it is preferable not to perform heating by the furnace heater 15.

[0069] (Second Embodiment)

[0070] In the second embodiment, a modified example of the arrangement position of the furnace heater 15 in the temperature raising process is illustrated. Fig.10 As shown, in this embodiment, in the temperature raising step, the furnace heaters 15 are arranged in pairs to sandwich both outer side surfaces 10 of the lower portion of the formed body 3 from both sides in the thickness direction Y. That is, the furnace heaters 15 are arranged at a higher position than in the first embodiment.

[0071] (Third Embodiment)

[0072] In the third embodiment, a modified example of the arrangement position of the furnace heater 15 in the temperature raising process is illustrated. Fig.11 As shown, in this embodiment, in the temperature raising step, the furnace heater 15 is arranged in a state of being buried inside the lower part of the formed body 3. That is, the present invention is not limited to the case where the furnace heater 15 is arranged outside the formed body 3.

[0073] It should be noted that 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.

[0074] The shapes of the in-furnace heater 15 and the out-furnace heaters 17, 18, 19 are not particularly limited, and they may be rod-shaped heaters or planar heaters. In addition, the out-furnace heaters 17, 18, 19 may be omitted.

[0075] The in-furnace thermometer 16 may be disposed in the furnace through the opening 23 for disposing the first conveying roller 7 in the furnace.

[0076] If the furnace thermometer 16 is located at a position that does not hinder the conveyance of the molten glass Gm and the glass ribbon Gr, the furnace thermometer 16 may be kept in the forming furnace 2 during the production process. Alternatively, the furnace thermometer 16 may be omitted during the heating process and the production process. When the furnace thermometer 16 is omitted, the heating temperature of the furnace heater 15 during the heating process can be adjusted based on the furnace external thermometers 20, 21, and 22, for example.

[0077] In the temperature raising step, both width direction end portions of the formed body 3 may be pressed (pressurized) from both sides.

[0078] When transferring from the heating process to the production process, the furnace heater 15 may not be retreated, but only the heating of the furnace heater 15 may be stopped. In this case, an opening portion for arranging the heater 15 in the furnace independently of the opening portion 23 for arranging the first conveying roller 7 in the furnace may be provided.

[0079] In the above-mentioned embodiment, the glass sheet G is exemplified as the glass article, but the glass article is not limited thereto. The glass article may be, for example, a glass roll in which a glass ribbon Gr is wound around a core in a roll shape.

[0080] Description of Reference Numerals

[0081] 1 Glass object manufacturing device

[0082] 2 Forming furnace

[0083] 3 formed body

[0084] 4 Annealing furnace

[0085] 5 Cooling chamber

[0086] 6 Cutting chamber

[0087] 7 First transport roller (edge ​​roller)

[0088] 13. Second transport roller (annealing roller)

[0089] 14 Third transport roller

[0090] 15 Furnace heater

[0091] 16 Furnace thermometer

[0092] 17 First furnace external heater

[0093] 18. Second external heater

[0094] 19 Third furnace external heater

[0095] 20 First furnace external thermometer

[0096] 21. Second furnace external thermometer

[0097] 22 The third furnace external thermometer

[0098] 23 Opening

[0099] G Glass Plate

[0100] Gm Molten glass

[0101] Gr Glass tape.

Claims

1. A method for manufacturing a glass article, using an overflow down-draw method, The method for manufacturing the glass article is characterized by comprising: A heating step of heating the formed body disposed in the forming furnace; as well as A forming step of supplying molten glass to the heated forming body and forming a glass ribbon from the molten glass, In the temperature raising step, the lower portion of the formed body is heated by a furnace heater disposed in the forming furnace. After the molten glass is supplied to the forming body, the in-furnace heater is retracted from a position where the lower portion of the forming body is heated to the outside of the forming furnace.

2. The method for manufacturing a glass article according to claim 1, wherein: After the molten glass is supplied to the forming body, the heating of the lower portion of the forming body by the in-furnace heater is reduced or stopped.

3. The method for manufacturing a glass article according to claim 1 or 2, wherein: The furnace heaters are arranged in pairs so as to sandwich both outer side surfaces of the lower portion of the forming body in the thickness direction of the glass ribbon or a passage portion of the glass ribbon below the lower portion of the forming body from both sides in the thickness direction.

4. The method for manufacturing a glass article according to claim 1 or 2, wherein: The in-furnace heater is disposed in the forming furnace through an opening for a conveying roller of the glass ribbon provided in a side wall portion of the forming furnace.

5. The method for manufacturing a glass article according to claim 1 or 2, wherein: In the temperature raising step, a thermometer for measuring the temperature of the lower portion of the formed body is disposed in the forming furnace.

6. The method for manufacturing a glass article according to claim 1 or 2, wherein: Outside the forming furnace, a first furnace heater for heating the upper part of the formed body is arranged at a position corresponding to the upper part of the side wall of the forming furnace, a second furnace heater for heating the lower part of the formed body is arranged at a position corresponding to the lower part of the side wall of the forming furnace, and a third furnace heater for heating the upper part of the formed body is arranged at a position corresponding to the top of the forming furnace. In the temperature raising step, the formed body is further heated by the first heater outside the furnace, the second heater outside the furnace, and the third heater outside the furnace.

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