Provided is a method for producing a glass substrate that can reduce the dimensional change during heat treatment while avoiding shortening of facilities' service lives. A method for producing a glass substrate includes melting and forming a glass raw material to produce a glass substrate having a strain point of 690 to 750° C., wherein an average cooling rate in a temperature range from (an annealing point plus 150° C.) to (the annealing point minus 200° C.) in a cooling process during the forming is adjusted to 100 to 400° C./min to obtain the glass substrate having a degree of thermal contraction of 15 ppm or less when subjected to a heat treatment at 500° C. for an hour.

Provided is a method for producing a glass substrate that can reduce the dimensional change during heat treatment while avoiding shortening of facilities' service lives. A method for producing a glass substrate includes melting and forming a glass raw material to produce a glass substrate having a strain point of 690 to 750° C., wherein an average cooling rate in a temperature range from (an annealing point plus 150° C.) to (the annealing point minus 200° C.) in a cooling process during the forming is adjusted to 100 to 400° C./min to obtain the glass substrate having a degree of thermal contraction of 15 ppm or less when subjected to a heat treatment at 500° C. for an hour.

A forming body of a glass forming apparatus may include a first conduit comprising a first conduit wall and at least one slot in the first conduit wall, and a second conduit disposed above and vertically aligned with the first conduit, the second conduit comprising a second conduit wall and a slot extending through the second conduit wall. The forming body may include a first vertical wall and a second vertical wall extending between an outer surface of the second conduit wall and an outer surface of the first conduit wall at a first side and a second side, respectively, of the forming body. The forming body may include a first forming surface and a second forming surface extending from an outer surface of the first conduit wall and converging at a root of the forming body. Methods of forming a continuous laminate glass ribbon are also disclosed.

A forming body of a glass forming apparatus may include a first conduit comprising a first conduit wall and at least one slot in the first conduit wall, and a second conduit disposed above and vertically aligned with the first conduit, the second conduit comprising a second conduit wall and a slot extending through the second conduit wall. The forming body may include a first vertical wall and a second vertical wall extending between an outer surface of the second conduit wall and an outer surface of the first conduit wall at a first side and a second side, respectively, of the forming body. The forming body may include a first forming surface and a second forming surface extending from an outer surface of the first conduit wall and converging at a root of the forming body. Methods of forming a continuous laminate glass ribbon are also disclosed.

An optical fiber coating apparatus that provides increased gyre stability and reduced gyre strength, thereby providing a more reliable coating application process during fiber drawing includes a cone-only coating die having a conical entrance portion with a tapered wall angled at a half angle , wherein 225, and a cone height L.sub.1 less than 2.2 mm, and a cylindrical portion having an inner diameter of d.sub.2, wherein 0.1 mmd.sub.20.5 mm and a cylindrical height of L.sub.2, wherein 0.05 mmL.sub.21.25 mm; a guide die having an optical fiber exit, the guide die disposed adjacent the cone-only coating die such that a wetted length (L.sub.5) between the optical fiber exit of the guide die and the entrance of the cone-only coating die is from 1 mm to 5 mm; and a holder for holding the cone-only coating die and the guide die in a fixed relationship defining a coating chamber between the guide die and the cone-only coating die, the coating chamber having an inner radius L.sub.6 from the optical fiber axis to an inner wall of the holder that is from 3 mm to 10 mm.

A method of manufacturing a glass sheet stably reduces a variation in a thermal shrinkage rate to 15 ppm or less. The method includes a melting step of melting, in an electric melting furnace, a glass batch prepared so as to give glass comprising 3 mass % or less of B.sub.2O.sub.3, a forming step of forming a molten glass into a sheet-shaped glass, an annealing step of annealing the sheet-shaped glass in an annealing furnace, and a cutting step of cutting the annealed sheet-shaped glass into predetermined dimensions, to thereby obtain a glass sheet having a -OH value of less than 0.2/mm and a thermal shrinkage rate of 15 ppm or less. The method includes measuring a thermal shrinkage rate of the glass sheet and adjusting a cooling rate of the sheet-shaped glass in the annealing step depending on variation in thermal shrinkage rate with respect to a target value.

A method of manufacturing a glass sheet stably reduces a variation in a thermal shrinkage rate to 15 ppm or less. The method includes a melting step of melting, in an electric melting furnace, a glass batch prepared so as to give glass comprising 3 mass % or less of B.sub.2O.sub.3, a forming step of forming a molten glass into a sheet-shaped glass, an annealing step of annealing the sheet-shaped glass in an annealing furnace, and a cutting step of cutting the annealed sheet-shaped glass into predetermined dimensions, to thereby obtain a glass sheet having a -OH value of less than 0.2/mm and a thermal shrinkage rate of 15 ppm or less. The method includes measuring a thermal shrinkage rate of the glass sheet and adjusting a cooling rate of the sheet-shaped glass in the annealing step depending on variation in thermal shrinkage rate with respect to a target value.

Provided is a manufacturing apparatus (1) for a glass sheet, including roller pairs (5), which are configured to convey a glass ribbon (G) downward while sandwiching the glass ribbon (G) from both front and back sides, and are arranged in a plurality of vertical stages, wherein each of rollers forming each of the roller pairs (5) is formed so as to be movable between a sandwiching position for sandwiching the glass ribbon (G) a retracted position that is separated from a conveyance path (P) of the glass ribbon (G) and is capable of preventing contact of flying objects flying from above, and wherein, when the glass ribbon (G) during conveyance is damaged, the roller (5a) that is positioned below a damaged part of the glass ribbon (G) moves to the retracted position.

Provided is a manufacturing apparatus (1) for a glass sheet, including roller pairs (5), which are configured to convey a glass ribbon (G) downward while sandwiching the glass ribbon (G) from both front and back sides, and are arranged in a plurality of vertical stages, wherein each of rollers forming each of the roller pairs (5) is formed so as to be movable between a sandwiching position for sandwiching the glass ribbon (G) a retracted position that is separated from a conveyance path (P) of the glass ribbon (G) and is capable of preventing contact of flying objects flying from above, and wherein, when the glass ribbon (G) during conveyance is damaged, the roller (5a) that is positioned below a damaged part of the glass ribbon (G) moves to the retracted position.

A chemically toughenable or toughened glass is provided. The glass has, before chemical toughening, a thickness of at most 500 m. The glass, after chemical toughening, has a BACT (bendability and chemical toughenability) calculated as BACT=(CS*DoL)/(t*E) which is greater than 0.00050 and/or a NS (normalized stiffness) calculated as NS=CS/E which is greater than 0.0085, where CS is a compressive stress in MPa measured at one side of the glass after chemical toughening, DoL is a total depth of all ion-exchanged layers in m on one side of the glass after chemical toughening, t is a thickness of the glass in m after chemical toughening, and E is a E-modulus in MPa after chemical toughening.