摘要:
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.
摘要:
A glass substrate for a magnetic disk of the invention is a disk-shaped glass substrate for a magnetic disk where the substrate has a main surface and end face and is subjected to chemical reinforcement treatment, and is characterized in that the penetration length in the uppermost-portion stress layer on the main surface is 49.1 μm or less, and that assuming that an angle between the main surface and compressive stress in the stress profile by a Babinet compensator method is θ, a value y of {12·t·ln(tan θ)+(49.1/t)} is the penetration length in the uppermost-portion stress layer or less.
摘要翻译:本发明的磁盘用玻璃基板是用于磁盘的盘状玻璃基板,其中基板具有主表面和端面并进行化学强化处理,其特征在于,最上面的穿透长度 主表面的应力层为49.1μm以下,假设通过Babinet补偿方法在应力分布中的主表面与压缩应力之间的角度为θ,则{12·t·ln (tan& t s)+(49.1 / t)}是最上部应力层的贯通长度以下。
摘要:
The present invention provides a method for efficiently manufacturing a glass substrate for magnetic disk having good accuracy of a surface irregularity and an impact resistance. The method includes the steps of: performing press forming to molten glass to prepare a sheet glass material, the sheet glass material having a roughness of the principal surface of 0.01 μm or less and target flatness of a glass substrate for magnetic disk; chemically strengthening the sheet glass material by dipping the sheet glass material in a chemically strengthening salt, thereby preparing a disk substrate; polishing the principal surfaces of the disk substrate. A thickness of the sheet glass material prepared in the press forming step is larger than a target thickness of the glass substrate for magnetic disk by a polishing quantity of the principal surface polishing step.
摘要:
A method of manufacturing a glass blank for a magnetic recording medium glass substrate in which, after a pair of press molds placed so as to be opposed to each other in a horizontal direction with press-molding surfaces thereof and the temperatures of the press-molding surfaces being substantially the same are brought into contact with a molten glass gob substantially at the same time, press molding is carried out to produce plate glass and the plate glass continues to be pressed with the pair of molds, and then, when the plate glass is taken out, the duration time of pressing the plate glass is controlled so that the flatness of the glass blank is 10 μm or less, and a method of manufacturing a magnetic recording medium glass substrate, a method of manufacturing a magnetic recording medium, and an apparatus for manufacturing a glass blank for a magnetic recording medium glass substrate using the same.
摘要:
Provided is a method of manufacturing a glass blank for a magnetic recording medium glass substrate, including: manufacturing a glass blank by at least press molding a falling molten glass gob with a pair of press molds both so as to face each other in a direction perpendicular to a direction in which the molten glass gob falls, in which: the molten glass gob is formed of a glass material having a glass transition temperature of 600° C. or more; and when the press molding is carried out so that the molten glass gob is completely extended by pressure and molded into a flat glass between press-molding surfaces of the pair of press molds, at least a region in contact with the flat glass in each of the press-molding surfaces of the pair of press molds forms a substantially flat surface. Also provided are a method of manufacturing a magnetic recording medium glass substrate and a method of manufacturing a magnetic recording medium each using the method of manufacturing a glass blank for a magnetic recording medium glass substrate.
摘要:
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.
摘要:
Provided are a method of manufacturing a glass blank, the method including press-molding a molten glass gob under a state in which a separation mark formed on an upper surface of the molten glass gob faces at least one of the molding surface sides of a pair of press molds arranged facing each other in a horizontal direction, when the molten glass gob falls into a space between the pair of press molds, and a method of manufacturing a magnetic recording medium substrate and a method of manufacturing a magnetic recording medium, both using the glass blank.
摘要:
An aspect of the present invention relates to a glass substrate for a magnetic recording medium, which is comprised of glass with a glass transition temperature of equal to or greater than 600° C., an average coefficient of linear expansion at 100 to 300° C. of equal to or greater than 70×10−7/° C., a Young's modulus of equal to or greater than 81 GPa, a specific modulus of elasticity of equal to or greater than 30 MNm/kg, and a fracture toughness value of equal to or greater than 0.9 MPa·m1/2.
摘要:
A manufacturing method of a sheet glass material for magnetic disk, the method includes, dropping process for dropping a lump of molten glass; pressing process for sandwiching simultaneously the lump from both sides of the dropping path of the lump with surfaces of a pair of dies facing together, and performing press forming to the lump to obtain a sheet glass material, wherein at least one of the pair of dies has a convex shape with respect to the dropping path of the lump.
摘要:
A manufacturing method of a sheet glass material for magnetic disk, the method includes, dropping process for dropping a lump of molten glass; pressing process for sandwiching simultaneously the lump from both sides of the dropping path of the lump with surfaces of a pair of dies facing together, and performing press forming to the lump to obtain a sheet glass material, wherein at least one of the pair of dies has a concave shape with respect to the dropping path of the lump.