US 12,084,376 B2
Method for manufacturing glass substrate and method for manufacturing magnetic disk
Shuhei Azuma, Hung Yen (VN)
Assigned to HOYA CORPORATION, Tokyo (JP)
Appl. No. 17/263,019
Filed by HOYA CORPORATION, Tokyo (JP)
PCT Filed Jul. 26, 2019, PCT No. PCT/JP2019/029530
§ 371(c)(1), (2) Date Jan. 25, 2021,
PCT Pub. No. WO2020/022510, PCT Pub. Date Jan. 30, 2020.
Claims priority of application No. PCT/JP2018/028269 (WO), filed on Jul. 27, 2018.
Prior Publication US 2021/0230042 A1, Jul. 29, 2021
Int. Cl. C03B 33/02 (2006.01); B23K 26/53 (2014.01); C03B 33/04 (2006.01); C03C 19/00 (2006.01)
CPC C03B 33/0222 (2013.01) [B23K 26/53 (2015.10); C03B 33/04 (2013.01); C03C 19/00 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for manufacturing a glass substrate that includes an opening, comprising:
forming a line of an inner circumferential portion and a line of an outer circumferential portion by irradiating a laser beam along substantially concentric circles in a surface of a glass blank from which the glass substrate is obtained;
separating a portion on an inner side of the line of the outer circumferential portion of the glass blank and a portion on an outer side of the line of the outer circumferential portion of the glass blank from each other, by selectively heating an entirety of the portion on the outer side of the line of the outer circumferential portion with radiant heat without intentionally heating the portion on the inner side of the line of the outer circumferential portion, to cause the portion on the outer side of the line of the outer circumferential portion to thermally expand outward such that a diameter of an inner circumference of the portion on the outer side of the line of the outer circumferential portion is relatively larger than a diameter of an outer circumference of the portion on the inner side of the line of the outer circumferential portion, and to form a gap along the line of the outer circumferential portion; and
separating a portion on an inner side of the line of the inner circumferential portion of the glass blank and a portion on an outer side of the line of the inner circumferential portion of the glass blank from each other, by selectively heating an entirety of the portion on the outer side of the line of the inner circumferential portion with radiant heat without intentionally heating the portion on the inner side of the line of the inner circumferential portion, to cause the portion on the outer side of the line of the inner circumferential portion to thermally expand outward such that a diameter of an inner circumference of the portion on the outer side of the line of the inner circumferential portion is relatively larger than a diameter of an outer circumference of the portion on the inner side of the line of the inner circumferential portion, and to form a gap along the line of the inner circumferential portion, and
the selectively heating of the entirety of the portion on the outer side of the line of the inner circumferential portion with the radiant heat is performed
by placing, in a heating space between heaters for the separating of the portions on the inner and outer sides of the line of the inner circumferential portion, the portion on the outer side of the line of the inner circumferential portion,
the heaters for the separating of the portions on the inner and outer sides of the line of the inner circumferential portion being provided on both main surface sides of the glass blank, being in non-contact with main surfaces of the glass blank, and emitting the radiant heat, and
by placing, outside the heating space, the portion on the inner side of the line of the inner circumferential portion.