JP2017031018A - Float plate glass transfer roll, float plate glass transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transportation roll of a float plate glass capable of contributing to molding of a sheet glass having improved strength by preventing generation of fine flaws during transportation.SOLUTION: There is provided a transportation roll 7 of a float plate glass in which at least a part having a contact with a float plate glass 1 on the surface of a roll barrel part is constituted of carbon. In the transportation roll of the float plate glass, average strength by Ball-on-Ring method of the glass plate after a friction test by carbon is 190 N or higher.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a roll for conveying a float sheet glass and a method for conveying a float sheet glass.

  In the float method for forming a float plate glass, a float plate glass (glass ribbon) formed by a float bath is transported to a slow cooling furnace by a transport roll and gradually cooled while being transported.

  A plurality of transport rolls used for the transport are arranged in the slow cooling furnace, but in the low temperature region (400 ° C. to 500 ° C. or less) of the slow cooling furnace, the saliva part contacting the float plate glass is made of ceramics. A roll is being used.

  Since this ceramic is softer and has a lower rolling resistance than steel, there is an advantage that the float plate glass is hardly damaged. However, there are problems such as cullet (glass fragments) generated by slight cracking of the float plate glass that has been hardened because it is soft and sticks into the brim part, generating nano-level minute wrinkles on the bottom surface of the float plate glass being conveyed. is there.

  In recent years, thin glass has been used for televisions, smartphones, and the like, and if there are minute nano-level wrinkles on the surface of such thin glass due to contact with the brim portion, it will directly lead to strength deterioration.

In view of the above points, for example, in a slow cooling furnace, there is a technique in which sulfurous acid gas (SO ₂ gas) is sprayed onto a float plate glass by a nozzle disposed between transport rolls. Sulfurous acid gas reacts with the components of the float plate glass, so that a protective film of sodium sulfate (Na ₂ SO ₄ ) can be generated on the surface of the float plate glass, and this protective film prevents wrinkles that occur during transportation. For example, Patent Document 1 discloses that strength deterioration can be suppressed.

International Publication No. 2002/51767

  However, the technique of Patent Document 1 has the following problems. That is, sulfurous acid gas is sprayed toward the float plate glass from a nozzle installed between the conveying rolls. Therefore, it is difficult to uniformly form a protective film of sodium sulfate on the entire surface of the float plate glass, and there is a possibility that a thin part of the protective film or a fragile part where the protective film is not generated exists. Then, nano level minute wrinkles are generated in the fragile portion due to contact with the brim portion of the conveying roller, leading to deterioration of the strength of the manufactured thin plate glass.

  The present invention has been made in view of the above problems, and provides a float sheet glass conveyance roll that can prevent the formation of minute wrinkles during conveyance and contribute to the formation of thin glass with improved strength. It is in.

In order to solve the above problems, according to one aspect of the present invention,
A float plate glass transport roll composed of carbon at least in contact with the float plate glass on the surface of the roll body,
There is provided a roll for conveying a float sheet glass in which the average strength of the glass sheet after the friction test using carbon is 190 N or more according to the Ball on Ring method.

  According to one aspect of the present invention, it is possible to provide a float sheet glass conveyance roll that can prevent the formation of minute wrinkles during conveyance and contribute to the formation of thin glass with improved strength.

It is a section explanatory view of a slow cooling furnace where a roll for float glass sheet conveyance concerning one embodiment of the present invention is arranged. It is a figure which shows partially an example of the roll for float glass plate conveyance which concerns on one Embodiment of this invention. It is a figure which shows the arrangement pattern of the roll for float glass plate conveyance which concerns on one Embodiment of this invention. It is a table | surface which shows the result of the strength test in Example 1 and Comparative Examples 1 and 2. FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof is omitted. In this specification, “to” representing a numerical range means a range including numerical values before and after the numerical range.

  FIG. 1 is a cross-sectional explanatory view of a slow cooling furnace in which a float glass transport roll according to an embodiment of the present invention is arranged.

  As shown in the drawing, the float glass sheet 1 formed in a ribbon shape on the molten tin 2 of the float bath 3 is melted by the lift-out roll 8 installed in the lift-out part 4 disposed at the outlet of the float bath 3. And is conveyed to a slow cooling furnace 5 disposed adjacent to the lift-out unit 4. In the lift-out part 4, several rolls other than the lift-out roll 8 are arranged at a position higher than the molten tin surface. The float glass plate 1 formed into a ribbon shape by the float bath 3 is pulled up by the lift-out roll 8 and then cooled in the lift-out portion 4 having the enclosure structure 10 to be sent to the slow cooling furnace 5 as a stable ribbon-like glass. It is done.

  The slow cooling furnace 5 is provided with a plurality of transport rolls 7 for transporting the float glass sheet 1. These transport rolls 7 are driven by a drive motor (not shown) to transport the ribbon-like float glass sheet 1. The transport roll 7 disposed in the slow cooling furnace 5 includes a transport roll 71 disposed in the high temperature region C1 (upstream side) of the slow cooling furnace 5 and a transport roll 72 disposed in the low temperature region C2 (downstream side) of the slow cooling furnace 5. It consists of.

  The roll for glass sheet conveyance corresponding to the present invention is a conveyance roll 72. This conveyance roll 72 is arrange | positioned at the low temperature area | region C2 side of the slow cooling furnace 5, and if it says further, it will be arrange | positioned in the area | region where the float glass plate 1 will be 400 degrees C or less. The rolls 71 and 72 for conveyance are substantially the same in overall shape, but are different in the configuration of the portion in contact with the float glass sheet 1. This point will be described later. Hereinafter, the transport roll 72 according to the present invention is referred to as a low temperature transport roll 72 and is distinguished from the transport roll 71 disposed in the high temperature region C1.

  The float glass sheet 1 transported from the lift-out unit 4 is strained at a glass temperature so that undesirable thermal stress does not remain while being transported by the transport roll 7 (the transport roll 71 and the low-temperature transport roll 72) in the slow cooling furnace 5. Slowly cooled to the following.

  The float glass sheet 1 is cooled to a temperature at which it can be cut in the slow cooling furnace 5, and then cut into a predetermined size by a cutting device 15 in a cutting work place located downstream of the slow cooling furnace 5. In the present embodiment, the temperature at which the float glass sheet 1 can be cut is usually around room temperature, but may be slightly higher.

(Conveying roll)
Next, the low temperature conveyance roll 72 of this invention is demonstrated based on drawing. In FIG. 2, an example of the low-temperature conveyance roll 72 which concerns on one Embodiment of this invention arrange | positioned in the low temperature area | region C2 started from the downstream of the slow cooling furnace 5 was partially shown. FIG. 2 is a view when viewed from the front in the conveying direction of the float glass sheet 1 (arrow X in FIG. 1).

  In the low temperature region C2 starting from the downstream side of the slow cooling furnace 5, the ambient temperature is, for example, 400 ° C. or lower. In this temperature region, the float glass sheet 1 is cooled and the surface is hardened.

  The low-temperature transport roll 72 that transports the float plate glass 1 in this state includes a rotation shaft portion 720 that forms a roll body portion, and a flange portion 721 that is provided on the outer periphery of the rotation shaft portion 720 and whose surface is in contact with the float plate glass 1. Composed.

The flange portion 721 is a ring-shaped annular member that surrounds the outer peripheral surface of the rotating shaft portion 720, and at least the surface thereof is formed of carbon having an appropriate hardness. The brim portion 721 has a carbon shore hardness of 20 to 85 HS and a Young's modulus of 5 to 20 GPa.
It is said that.

  Since the low-temperature transport roll 72 having the carbon brim portion 721 has an appropriate hardness, a minute crack of the float plate glass 1 pierces the brim portion 721 and generates wrinkles on the bottom surface of the float plate glass 1. There is no fear of doing it. Therefore, the strength of the manufactured thin glass can be improved.

  In addition, since the plurality of flange portions 721 are provided at intervals along the axial direction of the rotating shaft portion 720, the contact area with the float glass sheet 1 is small, and the probability that wrinkles are generated can be reduced. Moreover, the low temperature conveyance roll 72 is arrange | positioned in the low temperature area | region C2. Since the float plate glass 1 in this region is cooled and hardened, even if the flange portion 721 of the low-temperature transport roll 72 partially supports the float plate glass 1 along the width direction, the float plate glass 1 does not hang down due to its own weight. Almost no.

  The rotating shaft portion 720 may be the same as that of, for example, a conventional roll for conveying sheet glass. The size, material, shape, and the like of the rotating shaft portion 720 are not particularly limited, and may be the same as a conventional one such as stainless steel. The rotating shaft portion 720 is separated from the float glass sheet 1 by a plurality of flange portions 721 provided on the outer periphery of the rotating shaft portion 720.

  The brim part 721 rotates together with the rotating shaft part 720 and conveys the float glass sheet 1 in a predetermined direction. The flange portion 721 is formed separately from the rotation shaft portion 720 and is detachably fitted to the outer periphery of the rotation shaft portion 720.

  In addition, in this embodiment, although the rotating shaft part 720 and the collar part 721 are separately formed so that attachment or detachment is possible, you may form integrally.

  FIG. 3 is a diagram illustrating an arrangement pattern example of the brim portion 721 of the low-temperature conveyance roll 72 arranged in the low temperature region C2. 3A is a plan view, and FIG. 3B is a view when viewed from the front in the conveying direction of the float glass sheet 1 (arrow X in FIG. 3A).

  As shown in FIG. 3, the plurality of brim portions 721-1 to 721-4 included in the plural (for example, four) low-temperature conveyance rolls 72-1 to 72-4 do not overlap each other in a predetermined direction (conveyance direction). May be placed in position.

  When a defect such as a defect occurs on the surface of the float glass sheet 1 due to the rotation of the plurality of low-temperature transport rolls 72-1 to 72-4, the defect position in the width direction of the float glass sheet 1 is examined, thereby causing a problem. The transport roll can be easily identified. As a case where a defect occurs, for example, a case where foreign matter adheres to the outer peripheral surface of any of the plurality of brim portions 721-1 to 721-4 or wrinkles are formed. In these cases, a defect is formed on the surface of the float glass sheet 1 each time the low-temperature transport rolls 72-1 to 72-4 make one rotation. Defects appear periodically at intervals in the conveying direction of the float glass sheet 1. The low-temperature transport roll 72 that causes a malfunction is repaired or replaced.

  A plurality of conveyance roll groups including a plurality of low-temperature conveyance rolls 72-1 to 72-4 may be provided in a predetermined direction (conveyance direction). Also in this case, by examining the position of the defect in the width direction of the float glass sheet 1, it is possible to narrow down the transport roll candidates that cause the problem.

  As a method for further narrowing down the candidates, the plurality of candidates are divided into two groups, the low temperature transport roll 72 belonging to one group is separated from the float glass sheet 1, and the defect disappears when the low temperature transport roll 72 is rotated. Can be examined.

  In the above embodiment, the four low-temperature transport rolls 72-1 to 72-4 have the flange portions 721-1 to 721-4 having different arrangement patterns, but the number of arrangement patterns of the flange portions is not limited. It may be a staggered arrangement.

<Manufacturing method>
The manufacturing method of the float sheet glass of this embodiment may be the same as the manufacturing method of the conventional float sheet glass except using the low-temperature conveyance roll 72 of this invention in order to convey the float sheet glass 1 of 400 degrees C or less. With reference to FIG. 1 again, the manufacturing method of the float plate glass using the low-temperature conveyance roll 72 of the said structure is demonstrated.

  For example, after supplying a glass raw material to the melting furnace set to about 1600 degreeC and obtaining the molten glass 2, the molten glass 2 is poured into the float bath 3 with which molten tin was filled, and the float plate glass 1 is formed. There is a manufacturing method in which the float glass sheet 1 discharged from the float bath 3 and supplied to the slow cooling furnace 5 is cooled while being conveyed by a conveying roll 7. In particular, in the low temperature region C2 starting from the downstream side of the slow cooling furnace 5, the low temperature transport roll 72 having the carbon brim portion 721 of the present embodiment is disposed. The float glass sheet 1 is conveyed only to the low temperature region C2 where the temperature of the float glass sheet 1 is 400 ° C. or lower, using the low temperature conveyance roll 72 of the present embodiment. This is because carbon cannot be used by burning when the temperature exceeds 400 ° C.

  As mentioned above, according to the manufacturing method of the float plate glass which comprises the process which cools using the low-temperature conveyance roll 72 of this invention in order to convey the float plate glass 1 of 400 degrees C or less, the bottom of the float plate glass 1 is comprised. Generation | occurrence | production of the flaw in a surface can be suppressed and a thin glass with high intensity | strength can be manufactured.

  The plate thickness of the float glass sheet manufactured by being transported and cooled by the low-temperature transport roll 72 is, for example, 1.0 mm or less, preferably 0.7 mm or less. That is, the thickness of the flat portion of the float glass sheet is, for example, 1.0 mm or less, preferably 0.7 mm or less.

  The produced float glass is used as a glass substrate for display, a cover glass for display, and a window glass, for example.

The float glass plate to be produced may be alkali-free glass when used as a glass substrate for a display. The alkali-free glass is a glass that does not substantially contain an alkali metal oxide such as Na ₂ O, K ₂ O, or Li ₂ O. The alkali-free glass may have a total content of alkali metal oxides of 0.1% by mass or less.

Alkali-free glass, for example, represented by mass% based on _{oxide, SiO 2: 50% ~73%} , Al 2 O 3: 10.5% ~24%, B 2 O 3: 0% ~12%, MgO : 0% to 10%, CaO: 0% to 14.5%, SrO: 0% to 24%, BaO: 0% to 13.5%, MgO + CaO + SrO + BaO: 8% to 29.5%, ZrO ₂ : 0% Contains ~ 5%.

When the alkali-free glass has both a high strain point and high solubility, it is preferably expressed in terms of mass% on the basis of oxide, SiO ₂ : 58% to 66%, Al ₂ O ₃ : 15% to 22%, B ₂ O ₃ : 5% to 12%, MgO: 0% to 8%, CaO: 0% to 9%, SrO: 3% to 12.5%, BaO: 0% to 2%, MgO + CaO + SrO + BaO: 9% to Contains 18%.

When it is desired to obtain a particularly high strain point, the alkali-free glass is preferably expressed by mass% based on oxide, SiO ₂ : 54% to 73%, Al ₂ O ₃ : 10.5% to 22.5%, _{B 2 O 3: 0% ~5.5} %, MgO: 0% ~10%, CaO: 0% ~9%, SrO: 0% ~16%, BaO: 0% ~2.5%, MgO + CaO + SrO + BaO: 8 % To 26%.

  The float glass plate to be produced may be chemically strengthened glass when used as a cover glass for a display. What chemically-strengthened the glass for chemical strengthening is used as a cover glass. In the chemical strengthening treatment, ions having a small ion radius (for example, Li ions or Na ions) among alkali ions contained on the glass surface are replaced with ions having a large ion radius (for example, K ions) to obtain a predetermined depth from the glass surface. A compressive stress layer is formed.

Chemically strengthened glass, for example as represented by mol% based on _{oxides, SiO 2: 62% ~68%} , Al 2 O 3: 6% ~12%, MgO: 7% ~13%, Na 2 O: 9% to _17%, K 2 O: containing 0% to 7%, the difference obtained by subtracting the content of _Al 2 _{O 3} from the total content of Na ₂ O and _{K 2} O is less than 10%, a ZrO ₂ When it contains, the content is 0.8% or less.

Another chemically strengthened glass is represented by mol% based on _{oxides, SiO 2: 65% ~85%} , Al 2 O 3: 3% ~15%, Na 2 O: 5% ~15%, K 2 O : 0% to less than 2%, MgO: 0% to 15%, ZrO ₂ : 0% to 1%, the total content of SiO ₂ and Al ₂ O ₃ SiO ₂ + Al ₂ O ₃ is 88% or less It is.

The float glass plate to be produced may be soda lime glass when used as a window glass. Soda lime glass, for example, represented by mass% based on _{oxide, SiO 2: 65% ~75%} , Al 2 O 3: 0% ~3%, CaO: 5% ~15%, MgO: 0% ~15% , Na ₂ O: 10% to 20%, K ₂ O: 0% to 3%, Li ₂ O: 0% to 5%, Fe ₂ O ₃ : 0% to 3%, TiO ₂ : 0% to 5% CeO ₂ : 0% to 3%, BaO: 0% to 5%, SrO: 0% to 5%, B ₂ O ₃ : 0% to 5%, ZnO: 0% to 5%, ZrO ₂ : 0% _{~5%, SnO 2: 0%} ~3%, SO 3: contains 0% to 0.5%.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

  First, the inventors changed the material of the roll member used for the float glass transport roll (low temperature transport roll), and performed a friction test on the thin glass (test body) to compare the strength. .

  As the material of the roll member used for the friction test, carbon (Example 1), glass fiber carbon (Comparative Example 1), and ceramics (Comparative Example 2) used for the low-temperature transport roll of the present invention were used.

The carbon of Example 1 has a Shore hardness of 35 HS and a Young's modulus of 7 to 9 GPa. Further, a thermal expansion coefficient of 3.0 × 10 ⁻⁶ / ° C. and a maximum carbon particle diameter of 0.8 mm were used.

  The glass fiber carbon of Comparative Example 1 was made by New Hudson.

  The ceramic of Comparative Example 2 was non-asbestos, and a product made by New Hudson was used.

Moreover, the thin glass used as the test body contains 68% of SiO ₂ , 10% of Al ₂ O ₃ , 14% of Na ₂ O, 8% of MgO, 50 mm in length, expressed in mol% based on oxide. Three test samples were prepared using glass for chemical strengthening processed to a width of 50 mm and a thickness of 0.7 mm.

  The friction test was performed by the following method. A roll member whose load was adjusted so that the contact pressure with the test body was 0.2 MPa was brought into contact with one upper surface of the test body. Thereafter, the roll member was moved 5 mm at a speed of 100 mm / min while maintaining a contact pressure of 0.2 MPa. The same operation was repeated three times with a shift of 1 mm in the direction perpendicular to the moving direction. That is, a total of four linear scratches having a length of 5 mm were formed on the upper surface of the test body at intervals of 1 mm. The contact pressure was confirmed using a Fujifilm pressure measurement sheet (PRESCALE LLLWPS 270X200 5S).

  The above friction test was repeated 20 times for each roll member (Example 1, Comparative Examples 1 and 2), and then the average strength was determined by the BoR (Ball on Ring) method.

  The Ball on Ring method is introduced in, for example, ASTM Standard F-394 and the like, but in the present invention, measurement was performed by the following method.

  Placed on a stainless steel ring with a diameter of 30 mm and a rounded part with a radius of curvature of 2.5 mm so that one side of the specimen faces downward and a steel ball with a diameter of 10 mm contacts the other side of the specimen. I let you. The sphere was loaded at the center of the ring under static load conditions, and the breaking load (unit N) when the specimen was broken was defined as the BoR strength. The BoR intensity was measured 20 times, and the average value was taken as the average intensity. However, if the fracture starting point of the specimen is away from the position directly below the steel ball on one side of the specimen, it is excluded from the data for calculating the average value.

  The result is shown in FIG.

  Focusing on the average strength of the test results, Example 1 shows a high strength value of 230N. This is twice to seven times that of Comparative Example 1 and Comparative Example 2. This means that wrinkles that cause strength deterioration in the test specimen are not generated.

  Therefore, when the float glass sheet is conveyed by the low-temperature conveyance roll 72 using Example 1, it is possible to prevent generation of minute wrinkles that induce strength deterioration on the bottom surface of the float glass sheet. It can be seen that the strength can be secured.

The roll for glass sheet conveyance according to the present invention has a configuration in which the brim portion that comes into contact with the glass sheet is made of carbon, and is arranged as a low temperature conveyance roll in a low temperature region of 400 ° C. or lower of the slow cooling furnace. Further, the carbon has a Shore hardness of 20 to 85 HS, a Young's modulus of 5 to 20 GPa, and a thermal expansion coefficient of 0.5 × 10 ⁻⁶ / ° C. to 6 × 10 ⁻⁶ / ° C. When the diameter is 0.01 to 3.5 mm, it is possible to prevent nano level minute wrinkles that cause strength deterioration on the bottom surface of the thin float glass sheet. In this way, the strength (BoR strength) of the manufactured thin glass can be dramatically improved.

  As mentioned above, although embodiment of the roll for glass sheet conveyance and the manufacturing method of float glass sheet etc. was described, this invention is not limited to the said embodiment etc., In the range of the summary of this invention described in the claim Various modifications and improvements are possible.

DESCRIPTION OF SYMBOLS 1 Float glass 2 Molten tin 3 Float bath 4 Lift-out part 5 Slow cooling furnace 7 Transport roll 71 Upstream transport roll 72 Downstream transport roll (low temperature transport roll)
720 Rotating shaft portion 721 Head portion 8 Lift out roll 15 Cutting device

Claims (10)

A float plate glass transport roll composed of carbon at least in contact with the float plate glass on the surface of the roll body,
The roll for glass sheet | seat conveyance which the average intensity | strength by the following Ball on Ring method of the glass plate after the following friction test by the said carbon is 190 N or more.
(The friction test)
The carbon is brought into contact with one surface of a glass plate having a length of 50 mm, a width of 50 mm, and a thickness of 0.7 mm so that the contact pressure with the carbon is 0.2 MPa. Thereafter, the carbon is moved 5 mm with respect to the glass plate at a speed of 100 mm / min while maintaining a contact pressure of 0.2 MPa. The same operation is repeated three times with a shift of 1 mm in the direction orthogonal to the moving direction. That is, a total of four linear scratches having a length of 5 mm are formed on the upper surface of the glass plate at intervals of 1 mm. A friction test is performed on a total of 20 glass plates.
(The above Ball on Ring method)
On a ring made of SUS304 having a diameter of 30 mm and a contact portion rounded with a radius of curvature of 2.5 mm and mirror-polished, the glass plate is placed so that one side faces downward, and the other side of the glass plate is placed on the other side. A 10 mm diameter mirror-polished steel ball made of SUS304 is brought into contact. The steel ball is loaded at the center of the ring under static load conditions, and the breaking load (unit N) when the glass plate is broken is defined as BoR strength. The BoR intensity is measured 20 times, and the average value is defined as the average intensity. However, when the fracture starting point of the glass plate is away from the position directly below the steel ball on one surface side of the glass plate, it is excluded from the data for calculating the average value.   The roll for glass sheet conveyance according to claim 1, wherein the carbon has a Shore hardness of 20 to 85 HS.   The roll for glass sheet conveyance according to claim 1 or 2, wherein the Young's modulus of the carbon is 5 to 20 GPa. The roll for glass sheet conveyance according to any one of claims 1 to 3, wherein the carbon has a coefficient of thermal expansion of 0.5 × 10 ^-6 / ° C to 6 × 10 ^-6 / ° C.   The float roll glass conveyance roll according to any one of claims 1 to 4, wherein the carbon has a maximum particle size of 0.01 to 3.5 mm.   The roll roll glass conveyance roll according to any one of claims 1 to 5, wherein the roll body portion has a brim portion, and at least a portion of the surface of the brim portion that is in contact with the float plate glass is composed of the carbon. .   The float for conveying a flat sheet glass according to claim 6, wherein a plurality of the flange portions are provided at intervals along the axial direction of the roll body portion.   The float plate glass conveyance roll according to claim 7, wherein the plurality of flange portions included in the plurality of float plate glass conveyance rolls are arranged at positions that do not overlap each other in the conveyance direction of the float plate glass.   The manufacturing method of float plate glass which has the process of carrying out slow cooling using the roll for float plate glass conveyance of any one of Claims 1-6 in the downstream of the slow cooling furnace which anneals the said float plate glass. In the transporting and slow cooling step,
The float sheet glass manufacturing method according to claim 9, wherein the float sheet glass transporting roll transports the float sheet glass at 400 ° C. or lower.

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