JP7302401B2 - Sheet glass manufacturing apparatus and sheet glass manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sheet glass manufacturing apparatus and a sheet glass manufacturing method.

Metal transport rolls are used to transport sheet glass formed from molten glass. For example, Patent Literature 1 discloses, as a transport roll used for transporting float glass, a transport roll having an outer peripheral surface formed of a coating of a cobalt-based alloy.

JP-A-08-175828

When transporting a glass ribbon (hereinafter also referred to as plate glass) formed from molten glass as described above, if a metal transport roll is used, the outer peripheral surface of the transport roll is easily oxidized, and therefore the transport Scratches are likely to occur on the outer peripheral surface of the roll for use. When the outer peripheral surface of the transport roll is scratched, the scratch is transferred to the plate glass being transported, and cracks are likely to occur in the plate glass. Such a change in the state of the outer peripheral surface of the transport roll contributes to the deterioration of the quality of the plate glass. In addition, when the temperature of the sheet glass after molding drops rapidly during transportation, cracks are likely to occur in the sheet glass.

The present invention has been made in view of such circumstances, and an object thereof is to provide a plate glass manufacturing apparatus and a plate glass manufacturing method capable of maintaining good quality of the plate glass.

A sheet glass manufacturing apparatus that solves the above problems is a sheet glass manufacturing apparatus that includes a conveying unit that conveys a glass ribbon formed from molten glass, wherein the conveying unit includes a plurality of conveying rolls having an outer peripheral surface of ceramics. When the upstream transport roll is the first transport roll and the transport roll arranged downstream of the first transport roll is the second transport roll, the second transport roll The thermal conductivity of the outer peripheral surface is smaller than the thermal conductivity of the outer peripheral surface of the first transport roll.

According to this configuration, oxidation of the outer peripheral surface of the transport roll can be suppressed, so that scratches on the outer peripheral surface of the transport roll can be suppressed. As a result, it is possible to suppress deterioration of the quality of the plate glass caused by the transport roll. In addition, it is possible to reduce the thermal conductivity of the second transport roll arranged on the downstream side, suppress the sudden temperature drop of the glass ribbon, and prevent the glass ribbon from rapidly cooling. of cracks can also be reduced.

In the plate glass manufacturing apparatus, the plurality of transport rolls preferably include a transport roll having an outer peripheral surface of zirconia-based ceramics.
According to this configuration, among ceramics, zirconia-based ceramics have excellent heat resistance and excellent strength, so that changes in the state of the outer peripheral surface of the transport roll can be further suppressed.

In the plate glass manufacturing apparatus, the outer peripheral surface of the zirconia-based ceramics may be formed of a film of the zirconia-based ceramics.
In the plate glass manufacturing apparatus described above, it is preferable that the first transport roll has an outer peripheral surface of zirconia-based ceramics, and the second transport roll has an outer peripheral surface of silica-based ceramics.

Preferably, the plate glass manufacturing apparatus further includes an annealing furnace for annealing the glass ribbon, and the second transport roll is arranged in the annealing furnace.
According to this configuration, since the temperature difference between the glass ribbon and the outer peripheral surface of the second transport roll is small, it is possible to perform slow cooling of the glass ribbon more precisely.

The apparatus for manufacturing sheet glass described above includes a forming roll that rolls the molten glass using a roll-out forming method to form the glass ribbon, and the forming roll includes a first forming roll and the first forming roll. and a second forming roll disposed above the forming roll, wherein each of the first forming roll and the second forming roll has a cylindrical portion for rolling the molten glass, and the second forming roll The wall thickness of the cylindrical portion of the forming roll is preferably thinner than the wall thickness of the cylindrical portion of the first forming roll.

According to this configuration, the heat transferred to the outer peripheral surface of the cylindrical portion of the second forming roll can easily escape into the cylindrical portion. Thereby, the temperature rise of the outer peripheral surface of the cylindrical portion of the second forming roll can be suitably suppressed. The second forming roll tends to be hotter than the first forming roll. Therefore, the temperature difference between the first forming roll and the second forming roll can be reduced, and the molten glass can be prevented from sticking to the outer peripheral surface of the cylindrical portion of the second forming roll. Thereby, the unevenness of the main surface of the plate glass can be reduced.

In the plate glass manufacturing apparatus, the outer peripheral surface of at least one of the first forming roll and the second forming roll preferably has an uneven shape formed by knurling.

According to this configuration, the contact area between the outer peripheral surface of the forming roll and the molten glass is increased by the uneven shape formed by knurling. As a result, the heat of the molten glass is easily conducted to the forming rolls, so that the molten glass in contact with the outer peripheral surface of the forming rolls is easily cooled. The molten glass whose viscosity is increased by being cooled in this way enters the concave portion of the outer peripheral surface of the forming roll, thereby suppressing slippage between the outer peripheral surface of the forming roll and the molten glass. That is, the molten glass easily follows the rotation of the forming rolls, so that the molten glass is stably sent out from between the first forming roll and the second forming roll. Therefore, unevenness and waviness in the plate glass can be easily reduced.

In the plate glass manufacturing apparatus described above, it is preferable that an outer peripheral surface of at least one of the first forming roll and the second forming roll is formed of a Ni-based alloy film.

According to this configuration, the wettability of the molten glass to the Ni-based alloy film is excellent, so slippage between the outer peripheral surface of the forming roll and the molten glass can be further suppressed. This makes it possible to more easily reduce irregularities and undulations in the plate glass.

In the plate glass manufacturing apparatus, the plate glass may be radiation shielding glass.
A plate glass manufacturing method that solves the above problems uses the above-described plate glass manufacturing apparatus.

ADVANTAGE OF THE INVENTION According to this invention, the quality of plate glass can be maintained satisfactorily.

It is a schematic diagram showing a manufacturing apparatus of plate glass. It is a top view which shows a roll for conveyance. FIG. 4 is a partial plan view showing a forming roll; It is explanatory drawing explaining uneven|corrugated shape in the outer peripheral surface of a roll for shaping|molding.

An embodiment of a sheet glass manufacturing apparatus and a sheet glass manufacturing method will be described below with reference to the drawings. In the drawings, for convenience of explanation, part of the configuration may be exaggerated or simplified. Also, the dimensional ratio of each part may differ from the actual one.

<Overview of sheet glass manufacturing equipment>
As shown in FIG. 1, the plate glass manufacturing apparatus 11 of the present embodiment conveys a forming roll RA for forming a glass ribbon G2 by rolling a molten glass G1 using a roll-out forming method, and the glass ribbon G2. A transport section 12 is provided.

The forming roll RA of the plate glass manufacturing apparatus 11 includes a first forming roll 13 and a second forming roll 14 arranged above the first forming roll 13 . In the roll-out molding method, the molten glass G1 is rolled between the first molding roll 13 and the second molding roll 14 to form the glass ribbon G2. The conveying unit 12 of the plate glass manufacturing apparatus 11 includes a plurality of conveying rolls RB having an outer peripheral surface of ceramics. As shown in FIG. 2, the transport roll RB has an outer peripheral shape that contacts the entire width of the glass ribbon G2. The forming roll RA and the transport roll RB are driven to rotate about their axes by a drive unit (not shown).

<Forming roll>
As shown in FIG. 3, the outer peripheral surface of the second forming roll 14 of the plate glass manufacturing apparatus 11 has an uneven shape formed by knurling.

FIG. 4 is an explanatory diagram for explaining an uneven shape formed by knurling according to JIS B0951:1962. As shown in FIG. 4, the uneven shape formed by knurling is defined by using a perpendicular cross-section of the groove when it is assumed that the diameter of the second forming roll 14 is infinite. In FIG. 3, the groove pitch is indicated by pitch t, the groove depth by depth 2h, and the groove angle by angle θ (90° in FIG. 4).

The pitch t of the grooves formed by knurling is preferably in the range of 0.5 mm or more and 2.0 mm or less, more preferably 0.8 mm or more and 1.5 mm or less, and still more preferably 1 0 mm or more and 1.3 mm or less. The depth 2h of the grooves formed by knurling is preferably in the range of 1/4 or more and 3/4 or less, more preferably 1/3 or more and 1/2 or less of the groove pitch t. be. The angle θ of the grooves formed by knurling is preferably in the range of 60° or more and 120° or less, more preferably in the range of 80° or more and 100° or less.

Types of knurling include flat knurling and twill knurling as specified in JIS B0951:1962. The type of knurling is preferably twill knurling.

As shown in FIG. 3, the uneven shape formed by twill knurling includes a plurality of first inclined grooves 14a extending parallel to each other, and a plurality of first inclined grooves 14a extending parallel to each other while intersecting the first inclined grooves 14a. and a plurality of extending second inclined grooves 14b. The first inclined grooves 14a and the second inclined grooves 14b of the twill knurling are arranged so as to be inclined with respect to the flow direction MD of the molten glass G1 and the glass ribbon G2 (the direction orthogonal to the axial direction of the second forming roll 14). extends to

More specifically, the first inclined groove 14a extends so that the clockwise angle α with respect to the axis SL in a plan view of the second forming roll 14 is an acute angle. The angle α of the first inclined groove 14a is preferably in the range of 15° or more and 45° or less, more preferably 20° or more and 40° or less, and still more preferably 25° or more and 35° or less. is in the range. The second inclined groove 14b extends so that the counterclockwise angle β with respect to the axis SL in a plan view of the second forming roll 14 is an acute angle. The angle β of the second inclined groove 14b is preferably in the range of 15° or more and 45° or less, more preferably 20° or more and 40° or less, still more preferably 25° or more and 35° or less. is in the range. The angle α of the first inclined groove 14a and the angle β of the second inclined groove 14b may be the same angle or may be different angles.

Knurling is performed by transferring the uneven shape formed on the outer peripheral surface of the knurling piece to the surface to be processed. As an example of knurling, groove pitch t=1.256 mm (module m=0.4), groove depth 2h=t/2, angle θ=90°, angle α=30°, and angle β= A twill knurling set at 30° can be mentioned.

The outer peripheral surface of the second forming roll 14 is preferably made of a Ni-based alloy film. The Ni-based alloy film is provided on the knurled outer peripheral surface.
The Ni-based alloy contains Ni as a main component, and Hastelloy (registered trademark) is used, for example. Among Ni-based alloys, a Ni-based alloy corresponding to Hastelloy (registered trademark) C276 is suitable. Hastelloy (registered trademark) C276 contains, for example, 15% Cr, 16% Mo, 4% W, 5.5% Fe, 1% Mn, and 2.5% Co in mass%, It contains Ni as the balance.

The thickness of the Ni-based alloy film is preferably in the range of 30 μm or more and 300 μm or less, more preferably in the range of 100 μm or more and 200 μm or less.
The Ni-based alloy film can be composed of, for example, a plated film, but from the viewpoint of increasing the durability of the second forming roll 14 by suppressing peeling of the film, it is preferable to use a thermal spray film. more preferred. The thermal spraying method is not particularly limited, but for example, the HVOF thermal spraying method (high speed flame thermal spraying method) can be used.

The outer peripheral surface of the first forming roll 13 of the present embodiment is not particularly limited, but is preferably sandblasted. In addition, the outer peripheral surface of the first forming roll 13 is preferably formed of a Ni-based alloy film like the second forming roll 14, and more preferably formed of a Ni-based alloy thermal spray coating. The main body of the first forming roll 13 and the main body of the second forming roll 14, which serve as the base of the Ni-based alloy film, are made of a metal material other than the Ni-based alloy. A different metal layer may be further provided between the main body of the first forming roll 13 and the Ni-based alloy coating or between the main body of the second forming roll 14 and the Ni-based alloy coating.

As shown in FIG. 1, each of the first forming roll 13 and the second forming roll 14 has a cylindrical portion for rolling the molten glass G1. The wall thickness T2 of the cylindrical portion of the second forming roll 14 is preferably thinner than the wall thickness T1 of the cylindrical portion of the first forming roll 13 . The wall thickness T2 is more preferably within the range of wall thickness T1×0.50 or more and wall thickness T1×0.99 or less, more preferably wall thickness T1×0.60 or more and wall thickness T1×0. .90 or less.

The inside of the cylindrical portion of the first forming roll 13 and the inside of the cylindrical portion of the second forming roll 14 are preferably cooled using a cooling fluid. That is, it is preferable that the inside of the cylindrical portion of the first forming roll 13 and the inside of the cylindrical portion of the second forming roll 14 have flow paths through which the cooling fluid can flow. Further, the plate glass manufacturing apparatus 11 preferably includes a supply device for supplying a cooling fluid to the flow path in the cylindrical portion of the first forming roll 13 and the flow path in the cylindrical portion of the second forming roll 14 . The cooling fluid may be a liquid such as cooling water or a gas such as cooling air.

<Conveyor>
As shown in FIG. 1, the conveying unit 12 of the plate glass manufacturing apparatus 11 includes a first conveying roll 15 having an outer peripheral surface made of zirconia ceramics. A plurality of first transport rolls 15 are arranged along the flow direction MD of the glass ribbon G2, that is, the transport direction.

Zirconia-based ceramics include zirconia and ceramics containing zirconia as a main component. Ceramics containing zirconia as a main component are, for example, ceramics containing 50% by mass or more of zirconia, and components other than zirconia include, for example, calcia, yttria, and magnesia. As for the 1st conveyance roll 15, the outer peripheral surface which contacts the glass ribbon G2 should just be comprised from zirconia system ceramics at least.

The first transport roll 15 of the present embodiment is composed of a roll body 15a and a zirconia-based ceramic film 15b provided on the outer peripheral surface of the roll body 15a. The thickness of the zirconia-based ceramic film 15b is, for example, preferably in the range of 100 μm or more and 800 μm or less, more preferably in the range of 300 μm or more and 500 μm or less. The zirconia-based ceramic coating 15b of the first transport roll 15 is preferably a thermal spray coating. A thermal spray coating of zirconia-based ceramics can be formed, for example, using a thermal spraying method such as a well-known plasma thermal spraying method. The roll body 15a of the first transport roll 15 is preferably made of a metal material such as stainless steel.

The plurality of transport rolls RB in the transport section 12 of the plate glass manufacturing apparatus 11 further includes a second transport roll 16 disposed downstream of the first transport roll 15 in the flow direction MD of the glass ribbon G2. there is The second transport roll 16 has an outer peripheral surface made of silica-based ceramics. A plurality of second transport rolls 16 are arranged along the flow direction MD of the glass ribbon G2. Examples of silica-based ceramics include silica and ceramics containing silica as a main component. Ceramics containing silica as a main component are ceramics having a silica content of 50% by mass or more, and examples of components other than silica include alumina. As for the 2nd conveyance roll 16, the outer peripheral surface which contacts the glass ribbon G2 should just be comprised from silica-type ceramics at least. The second transport roll 16 is preferably a silica roll made of silica-based ceramics, for example, from the viewpoint of avoiding peeling of the film.

As described above, since the first transport roll 15 having the outer peripheral surface of zirconia-based ceramics and the second transporting roll 16 having the outer peripheral surface of silica-based ceramics are configured, the outer peripheral surface of the second transport roll 16 The thermal conductivity is smaller than the thermal conductivity of the outer peripheral surface of the first transport roll 15 .

<Slow cooling furnace>
The plate glass manufacturing apparatus 11 further includes an annealing furnace 17 for annealing the glass ribbon G2. The slow cooling furnace 17 is equipped with a heater (not shown). The interior of the slow cooling furnace 17 has a temperature gradient that decreases toward the downstream side in the flow direction MD. Thermal strain inside the glass ribbon G<b>2 is removed by passing the glass ribbon G<b>2 through the annealing furnace 17 . The second transport roll 16 in the transport section 12 described above transports the glass ribbon G<b>2 within the annealing furnace 17 . A sheet glass is obtained by slowly cooling the glass ribbon G2 in the slow cooling furnace 17 .

At least one transport roll RB among the plurality of transport rolls RB described above may be configured to be cooled by circulating a cooling fluid inside the transport roll RB.

<Method for manufacturing plate glass>
Next, a method for manufacturing sheet glass will be described together with main effects.
In the sheet glass manufacturing method, first, the molten glass G1 is rolled by the molding roll RA in the sheet glass manufacturing apparatus 11 to form the glass ribbon G2. At this time, the outer peripheral surface of the second forming roll 14 has an uneven shape formed by knurling. Therefore, the contact area between the outer peripheral surface of the second forming roll 14 and the molten glass G1 is enlarged by the uneven shape formed by knurling. Thereby, the heat of the molten glass G1 is easily conducted to the second forming roll 14, so that the molten glass G1 in contact with the outer peripheral surface of the second forming roll 14 is easily cooled. The molten glass G1 whose viscosity has been increased by being cooled in this way enters the recessed portion of the outer peripheral surface of the second forming roll 14, thereby causing the gap between the outer peripheral surface of the second forming roll 14 and the molten glass G1. is suppressed. That is, the molten glass G1 easily follows the rotation of the second forming roll 14, so that the molten glass G1 is stably sent out from between the first forming roll 13 and the second forming roll 14. become. Therefore, unevenness and waviness in the plate glass can be easily reduced.

In addition, since the wall thickness T2 of the cylindrical portion of the second forming roll 14 is thinner than the wall thickness T1 of the cylindrical portion of the first forming roll 13, the heat transmitted to the outer peripheral surface of the cylindrical portion of the second forming roll 14 is easily escapes into the cylindrical portion. As a result, it is possible to suitably suppress the temperature rise of the outer peripheral surface of the cylindrical portion of the second forming roll 14, so that it is possible to suppress the molten glass G1 from sticking to the outer peripheral surface of the cylindrical portion of the second forming roll 14. can.

In the method for manufacturing plate glass, the glass ribbon G<b>2 is transported by the transport unit 12 . At this time, the transport section 12 includes a plurality of transport rolls RB having an outer peripheral surface of ceramics. Also, the thermal conductivity of the outer peripheral surface of the second transport roll 16 is lower than the thermal conductivity of the outer peripheral surface of the first transport roll 15 . According to this configuration, oxidation of the outer peripheral surface of the transport roll RB is suppressed, so that scratches on the outer peripheral surface of the transport roll RB can be suppressed. As a result, it is possible to suppress deterioration in the quality of the plate glass caused by the transport roll RB. In addition, the thermal conductivity of the second transport roll 16 arranged on the downstream side can be reduced, the rapid temperature drop of the glass ribbon G2 can be suppressed, and the glass ribbon G2 can be cooled rapidly. It is also possible to reduce the occurrence of cracks in the sheet glass caused by this.

The sheet glass produced in the present embodiment may be alkali-free glass or glass containing an alkali component. Uses of plate glass include, for example, display uses, touch panel uses, photoelectric conversion panel uses, electronic device uses, window glass uses, building material uses, and vehicle uses. Here, for example, radiation shielding glass (for example, glass containing PbO) used for building materials and the like has a relatively high temperature dependency of melt viscosity, and seizing on the outer peripheral surface of the forming roll and the outer periphery of the forming roll Slippage between surfaces is relatively easy to occur. In such a roll-out molding method for radiation shielding glass, it is particularly advantageous to use the second molding roll 14 of the present embodiment. The thickness of the sheet glass produced in this embodiment is not particularly limited, but is preferably in the range of 5 mm or more and 35 mm or less, for example.

Next, the operation and effects of this embodiment will be described.
(1) The conveying unit 12 of the plate glass manufacturing apparatus 11 includes a plurality of conveying rolls RB having an outer peripheral surface of ceramics. When the upstream transport roll RB is the first transport roll 15 and the transport roll RB arranged downstream of the first transport roll 15 is the second transport roll 16, the second transport roll The thermal conductivity of the outer peripheral surface of 16 is smaller than the thermal conductivity of the first transport roll 15 . According to this configuration, the quality of the plate glass can be maintained satisfactorily due to the above-described action.

(2) In the plate glass manufacturing apparatus 11, the plurality of transport rolls RB preferably include transport rolls having outer peripheral surfaces made of zirconia-based ceramics. In this case, among ceramics, zirconia-based ceramics have excellent heat resistance and excellent strength, so that changes in the state of the outer peripheral surface of the transport roll can be further suppressed. Therefore, the quality of the sheet glass can be maintained even better.

(3) The plate glass manufacturing apparatus 11 further includes a slow cooling furnace 17 that slowly cools the glass ribbon G2, and the second transport roll 16 is preferably arranged in the slow cooling furnace 17 . In this case, since the temperature difference between the glass ribbon G2 and the outer peripheral surface of the second transport roll 16 is small, the slow cooling of the glass ribbon G2 can be performed more precisely. Therefore, it is possible to easily improve the quality of the glass ribbon G2.

(4) The plate glass manufacturing apparatus 11 includes a first forming roll 13 and a second forming roll 14 arranged above the first forming roll 13, and the cylindrical portion of the second forming roll 14 is The wall thickness T2 is preferably thinner than the wall thickness T1 of the cylindrical portion of the first forming roll 13 . In this case, the temperature rise of the outer peripheral surface of the cylindrical portion of the second forming roll 14 can be suppressed appropriately. The second forming roll 14 tends to have a higher temperature than the first forming roll 13 . Therefore, the temperature difference between the first forming roll 13 and the second forming roll 14 can be reduced, and the molten glass G1 can be prevented from sticking to the outer peripheral surface of the cylindrical portion of the second forming roll 14 . Thereby, the unevenness of the main surface of the plate glass can be reduced.

(5) In the plate glass manufacturing apparatus 11, the outer peripheral surface of the second forming roll 14 preferably has an uneven shape formed by knurling. In this case, as described above, the molten glass G1 easily follows the rotation of the second forming roll 14, so that the molten glass G1 is stabilized from between the first forming roll 13 and the second forming roll 14. and will be sent out. Therefore, unevenness and undulations in the plate glass can be easily reduced.

(6) The outer peripheral surface of the second forming roll 14 is preferably made of a Ni-based alloy film. In this case, the wettability of the molten glass G1 with respect to the Ni-based alloy film is good, so slippage between the outer peripheral surface of the second forming roll 14 and the molten glass G1 can be further suppressed. This makes it possible to more easily reduce irregularities and undulations in the plate glass.

(Change example)
This embodiment can be implemented with the following modifications. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.

- In the conveying section 12, the zirconia-based ceramics of the first conveying roll 15 may be changed to other ceramics, and the silica-based ceramics of the second conveying roll 16 may be changed to other ceramics. That is, the ceramics used for the outer peripheral surface of the transport roll RB is not limited to the ceramics described above, and may be, for example, alumina-based ceramics, yttria-based ceramics, or the like. The transport rolls RB in the transport unit 12 may include three or more types of transport rolls having outer peripheral surfaces made of ceramics different from each other.

However, since the conveying roll RB arranged at the position closest to the forming roll RA of the sheet glass manufacturing apparatus 11 is in contact with the glass ribbon G2 at a relatively high temperature, it is made of zirconia having excellent heat resistance and excellent strength. It is preferable to construct the transport roll having an outer peripheral surface of ceramics.

- You may arrange|position the roll 16 for 2nd conveyance which has the outer peripheral surface of silica-type ceramics so that the glass ribbon G2 may be conveyed out of the slow cooling furnace 17. As shown in FIG.
- The conveyance part 12 of the manufacturing apparatus 11 of plate glass may be equipped with the conveyance roll which has outer peripheral surfaces other than ceramics.

- In the plate glass manufacturing apparatus 11, the configuration of the outer peripheral surface of the second forming roll 14 used in the roll-out forming method can also be applied to the outer peripheral surface of the first forming roll 13. The configuration of the outer peripheral surface of the second forming roll 14 can also be applied only to the outer peripheral surface of the first forming roll 13 .

In the plate glass manufacturing apparatus 11, the second forming roll 14 is arranged above the first forming roll 13, but it can also be arranged so as to face the first forming roll 13 in the horizontal direction.

- The configuration of the outer peripheral surface of the second forming roll 14 should be applied to at least the surface that contacts the molten glass G1, and the configuration of the outer peripheral surface that does not contact the molten glass G1 is not particularly limited.

- At least one of the first forming roll 13 and the second forming roll 14 may be changed to a solid forming roll having no cylindrical portion.
・In the sheet glass manufacturing apparatus 11, the forming method for forming the glass ribbon G2 from the molten glass G1 is not limited to the roll-out forming method, and may be, for example, a down-draw forming method, an overflow forming method, a float forming method, or the like. You can change it.

DESCRIPTION OF SYMBOLS 11... Plate glass manufacturing apparatus 12... Conveyance part 13... 1st shaping|molding roll 14... 2nd shaping|molding roll 15... 1st conveyance roll 15b... Film|membrane 16... 2nd conveyance roll 17... Slow cooling furnace, G1...Molten glass, G2...Glass ribbon, MD...Flow direction, RA...Shaping roll, RB...Transport roll, T1, T2...Wall thickness.

Claims (9)

A plate glass manufacturing apparatus comprising a forming roll for rolling molten glass using a roll-out forming method to form a glass ribbon, and a conveying unit for conveying the glass ribbon formed from the molten glass,
The forming roll comprises a first forming roll and a second forming roll disposed above the first forming roll,
Each of the first forming roll and the second forming roll has a cylindrical portion for rolling the molten glass,
The wall thickness of the cylindrical portion of the second forming roll is thinner than the wall thickness of the cylindrical portion of the first forming roll,
The transport unit includes a plurality of transport rolls having a ceramic outer peripheral surface,
When the upstream transport roll is a first transport roll and the transport roll arranged downstream of the first transport roll is a second transport roll, the outer peripheral surface of the second transport roll is smaller than the thermal conductivity of the outer peripheral surface of the first transport roll. The sheet glass manufacturing apparatus according to claim 1, wherein the plurality of transport rolls include a transport roll having an outer peripheral surface of zirconia-based ceramics. 3. The sheet glass manufacturing apparatus according to claim 2, wherein the outer peripheral surface of said zirconia-based ceramics is composed of a film of said zirconia-based ceramics. The first transport roll has an outer peripheral surface of zirconia ceramics,
The sheet glass manufacturing apparatus according to claim 2 or 3, wherein the second transport roll has an outer peripheral surface made of silica-based ceramics. Further comprising a slow cooling furnace for slowly cooling the glass ribbon,
The sheet glass manufacturing apparatus according to claim 4, wherein the second transport roll is arranged in the slow cooling furnace. The outer peripheral surface of at least one of the first forming roll and the second forming roll has an uneven shape formed by knurling, according to any one of claims 1 to 5 An apparatus for producing flat glass as described. 7. The outer peripheral surface of at least one of the first forming roll and the second forming roll is composed of a Ni-based alloy film, according to any one of claims 1 to 6 An apparatus for producing flat glass as described. A plate glass manufacturing apparatus comprising a conveying unit that conveys a glass ribbon formed from molten glass,
The plate glass is radiation shielding glass, and the transport unit includes a plurality of transport rolls having an outer peripheral surface of ceramics,
When the upstream transport roll is a first transport roll and the transport roll arranged downstream of the first transport roll is a second transport roll, the outer peripheral surface of the second transport roll is smaller than the thermal conductivity of the outer peripheral surface of the first transport roll . A method for manufacturing sheet glass, using the apparatus for manufacturing sheet glass according to any one of claims 1 to 8 .

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