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Title:
METHOD FOR PRODUCING GLASS SUBSTRATE FOR MAGNETIC DISK
Document Type and Number:
WIPO Patent Application WO/2019/151185
Kind Code:
A1
Abstract:
In the present invention, when a glass blank is being cut out from a glass plate, first laser light is moved relative to the glass plate such that a focal position of the laser light is located in the interior of a plate thickness direction of the glass plate and such that the focal position traces a circle as seen from a surface of the glass plate, whereby a cracking start section is formed in the glass plate interior. Thereafter, the cracking is advanced from the cracking start section to a principal surface of the glass plate, thus cutting the glass plate, and the glass blank is separated from the glass plate, the glass blank having a separation surface where the surface roughness is less than 0.01 μm in terms of arithmetic mean roughness Ra, and the roundness is 15 μm or less. Thereafter, the principal surface of the glass blank is ground or polished.

Inventors:
AZUMA, Shuhei (Plot A-9, Thang Long Industrial Park II Lieu Xa Commune, Yen My Distric, Hung Yen Province ., VN)
Application Number:
JP2019/002758
Publication Date:
August 08, 2019
Filing Date:
January 28, 2019
Export Citation:
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Assignee:
HOYA CORPORATION (6-10-1 Nishi-Shinjuku, Shinjuku-ku Tokyo, 47, 〒1608347, JP)
International Classes:
C03B33/09; B23K26/361; B23K26/53; B24B1/00; B24B7/24; B24B37/08; G11B5/84
Domestic Patent References:
WO2015002152A12015-01-08
Foreign References:
JP2009087409A2009-04-23
JP2009241154A2009-10-22
JP2015083320A2015-04-30
JP2015181085A2015-10-15
JP2017508691A2017-03-30
JP2012218103A2012-11-12
JP2015076115A2015-04-20
Attorney, Agent or Firm:
GLOBAL IP TOKYO (CARMEL II, 8-3-30 Nishi-Shinjuku, Shinjuku-k, Tokyo 23, 〒1600023, JP)
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