Hoya Corporation

Akira Murakami

Hideki Isono

Takashi Sato

Hidekazu Tanino

Masamune Sato

Shinji Eda

Yoshinori Iguchi

Tetsuya Saito

Katsumi Utsugi

Masahiro Yoshida

Jun Saito

Atsushi Uezaki

Yoshikane Shinkuma

Atsushi Watabe

Junichi Watanabe

Shizuo Suzuki

Toshio Sekiba

Takeo Otagiri

Katsuya Nagakura

Tomomasa Takeuchi

Masaru Onishi

Takumi Yata

A method for manufacturing a glass blank for magnetic disk and a method for manufacturing a glass substrate for magnetic disk are provided which are capable of producing a glass blank for magnetic disk having a good surface waviness by press forming. The method includes a forming process of press-forming a lump of molten glass using a pair of dies, wherein in the forming process, press forming is performed using thermally equalizing means for reducing a difference in temperature in the press forming surface of the die during pressing of the molten glass.

Method for manufacturing glass blank for magnetic disk, method for manufacturing glass substrate for magnetic disk, glass blank for magnetic disk

A method for manufacturing a glass substrate for magnetic disk is provided in which a glass is kept from being fused to a mold during press forming and shape processing to achieve a good circularity is efficiently performed. The method includes: a forming process of forming a disk-shaped glass blank by direct-pressing a molten glass by a pair of dies; and a shape processing process of performing at least one of inner hole formation and outer shape formation for forming a disk-shaped glass substrate by forming a cutting line on the principal face of the glass blank, followed by growing the cutting line to perform cutting. In the forming process, press forming is performed while the temperature of the pair of dies, over a period of time until a molten glass is separated from the die after coming into contact with the die, is set at a temperature lower than a glass transition point (Tg) and a mold release material is not attached to the surfaces of the pair of dies.

Method for manufacturing glass blank for magnetic disk, method for manufacturing glass substrate for magnetic disk

To provide a method for manufacturing a glass blank for magnetic disk and a method for manufacturing a glass substrate for magnetic disk, which are capable of producing a glass blank for magnetic disk having a good surface waviness by press forming, and a method for manufacturing a glass substrate for magnetic disk. A method for manufacturing a glass blank for magnetic disk, which includes a forming process of press-forming a lump of molten glass using a pair of dies, wherein in the forming process, press forming is performed using thermally equalizing means for reducing a difference in temperature in the press forming surface of the die during pressing of the molten glass.

Manufacturing method of glass blank for magnetic disk, manufacturing method of glass substrate for magnetic disk, glass blank for magnetic disk, glass substrate for magnetic disk, and magnetic disk

A method for manufacturing a glass substrate for magnetic disk, the internal strain of which is reduced without performing annealing treatment, is provided. The method includes a forming process of forming a plate-shaped glass blank by pressing a lump of molten glass using a pair of dies, wherein the method includes: a removing process of removing at least a part of a residual stress layer formed on the principal face of the glass blank press-formed in the forming process; and a process of forming a donut-shaped glass substrate by subjecting the glass blank after the removing process to machining.

Method for manufacturing glass substrate for magnetic disk

A method of manufacturing a glass blank for a substrate for an information recording medium, the method including steps of: cutting out a gob of a glass material from a molten glass material by cutting the molten glass material discharged from a glass material outlet at a predetermined timing; causing the gob of the glass material to fall downwardly; pinching and pressing the gob of the glass material by a press unit having a pair of molds, the molds' surfaces facing to each other being press surfaces which are planes without an unevenness, so as to contact the falling gob of the glass material only to the press surfaces; and forming a circular flat plate-shaped glass blank having a target flatness as a glass substrate for a magnetic disk such that a ratio between a diameter and a thickness of the glass blank is within a range of from 50:1 to 150:1, from the gob of the glass material.

Method of producing glass blank for substrate of information recording medium, substrate for information recording medium, and information recording medium; and manufacturing apparatus for glass blank for substrate of information recording medium

The present invention provides a manufacturing method of a sheet glass material excellent in flatness. A manufacturing method of glass substrate for magnetic disk including a pair of principal surfaces, the method comprising the steps of: dropping process for dropping a lump of molten glass; pressing process for forming a sheet glass material by performing press forming to the lump while sandwiching the lump from both sides of the dropping path of the lump with facing surfaces of a pair of dies, the pair of dies being set to substantially the same temperature; and processing process for processing the sheet glass material, while the lump drops down while revolving around its dropping axis.

Manufacturing method for a glass substrate for magnetic disk

A manufacturing method of a glass blank for magnetic disk including a pair of principal surfaces, the method including: dropping process for dropping a lump of molten glass; pressing process for forming a sheet glass material by sandwiching simultaneously the lump from both sides of the dropping path of the lump with surfaces of the pair of dies facing together, and performing press forming to the lump; and temperature adjusting process for adjusting temperature of the lump before the pressing process such that viscosity variation of the lump is reduced with respect to positions over the entirety of the lump in the pressing process.

Manufacturing method of a glass blank for magnetic disk and manufacturing method of a glass substrate for magnetic disk

A method of manufacturing high-quality preforms from glass melt, manufacturing glass elements, such as lenses, by press molding these preforms and, manufacturing optical elements by reheating and press molding these glass gobs. In the method glass gobs are continuously separated from a glass melt flow continuously flowing out of a nozzle and the separated glass gobs are formed with glass forming members that are intermittently or continuously moving. A support member is made to approach the front end of the nozzle, the front end of the glass melt flow is received by the support member, and the support member is dropped more rapidly than the rate of flow of the glass melt flow to separate a glass gob from the glass melt flow. The separated glass gob is transferred from the support member to a stopped or moving glass forming member to mold a glass article.

Method of manufacturing glass articles, method of manufacturing glass gobs, and method of manufacturing optical elements

A method for producing a thin-plate-shaped substrate blank that is an intermediate for a glass substrate, in which the occurrence of undulation is prevented and the substrate blank is produced with high accuracy, the method comprising press-molding a glass in a softened state with a mold having an upper mold member and a lower mold member to produce the thin-plate-shaped substrate blank, wherein the glass in a softened state is press-molded without causing any surrounding edge portion of the substrate blank under the production to come into contact with the mold, to produce the substrate blank at least having no notch portion.

Methods for producing substrate blank

A process for stably and efficiently producing quality glass articles such as preforms at high yields, and a process for producing an optical device from the preform obtained by the above process. In the process for producing a glass article, molten glass gobs having a predetermined weight each are poured, or molten glass drops having a predetermined weight each are dropped through a nozzle, into a boiling liquid having a boiling point lower than the class transition temperature of the glass constituting said glass article or a liquid which is temperature-adjusted beforehand so as to be caused to boil by the amount of heat of the glass, to form glass articles.

Processes for the production of glass article

There are disclosed a method of manufacturing a thin-plate glass having a good flatness with a high mass productivity and a method of manufacturing a high-quality and high-performance glass substrate for an information recording medium and a magnetic recording medium with a high mass productivity. A glass gob is press-formed between upper and lower dies to form a thin-plate glass. The press forming is finished when the inside of the thin-plate glass is at a softening point Ts or a higher temperature. Subsequently, warp modification pressing is performed to modify a warp of the thin-plate glass. The warp modification pressing is finished when the inside of the thin-plate glass is at a transition point Tg or a higher temperature.

Method of manufacturing thin-plate glass article, method of manufacturing glass substrate for information recording medium, and method of manufacturing magnetic recording medium

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Akiruno, Japan

Akira Murakami