Method for producing glass sheet with bent portion and glass sheet with bent portion
Provided is a method capable of producing a glass sheet with a bent portion in which a flattened portion has high flatness and high smoothness. A flat glass sheet 20 is radiationally heated with a first portion 21 thereof held between first and second heat-insulating members 31, 32 . And then, a second portion 22 a, 22 b of the flat glass sheet 20 not held between the first and second heat-insulating members 31, 32 is bent.
1. A method for producing a glass sheet with a bent portion, the glass sheet including a flattened portion and the bent portion continued to the flattened portion,
wherein a flat glass sheet is radiationally heated with a first portion of the flat glass sheet held between and in contact with first and second heat-insulating members and then a second portion of the flat glass sheet not held between the first and second heat-insulating members is bent while the first portion is held between and in contact with the first and second heat-insulating members,
wherein the flat glass sheet is heated by radiationally heating an entire region of the second portion until the first portion of the flat glass sheet reaches a temperature equal to or higher than a strain point of the flat glass sheet while the first portion is held between and in contact with the first and second heat-insulating members,
wherein the first and second heat-insulating members include a through hole and a coolant is fed through the through hole to control a temperature of the first and second heat-insulating members holding the first portion so as to avoid a temperature of the first portion from becoming above a softening point of the flat glass sheet, and
wherein the through hole is provided in an internal portion of the first and second heat-insulating members and is configured to direct coolant to the internal portion of the first and second heat-insulating members.
2. The method for producing a glass sheet with a bent portion according to claim 1 , wherein the flat glass sheet is heated so that the second portion of the flat glass sheet reaches a higher temperature than the first portion thereof.
3. The method for producing a glass sheet with a bent portion according to claim 1 , wherein the flat glass sheet used is a flat glass sheet having a linear coefficient of thermal expansion of 120×10 −7 /° C. or less at 30° C. to 380° C.
4. The method for producing a glass sheet with a bent portion according to claim 1 , wherein the heat-insulating members have a lower thermal conductivity than the flat glass sheet.
5. The method for producing a glass sheet with a bent portion according to claim 1 , wherein the heat-insulating members are formed of ceramic material.
6. The method for producing a glass sheet with a bent portion according to claim 1 , wherein the second portion is bent with the flat glass sheet pressed by the first and second heat-insulating members.
7. The method for producing a glass sheet with a bent portion according to claim 1 , wherein the flat glass sheet is heated by a heater disposed at a lateral side of the flat glass sheet.