Hoya Corporation

Shuhei Azuma

Toshio Takizawa

A method for producing an intermediate glass plate includes a defect formation step, a separation step, and a polishing step. In the defect formation step, a defect is formed on main surfaces of glass blanks by irradiating a laminate of the glass blanks with a laser beam from one side in a lamination direction in which the glass blanks are laminated, along the lamination direction, and moving the laser beam relative to the laminate such that a circle is drawn in a view from the main surfaces of the glass blanks. In the separation step, a cylindrical laminate is formed by separating a removal target portion along the defect while maintaining the laminate. In the polishing step, a side wall surface of the laminate is polished while maintaining the cylindrical laminate so as to obtain a disk-shaped intermediate glass plate that has been subjected to edge surface polishing.

Method for producing glass plate, and laminate

A disk-shaped glass substrate manufacturing method for manufacturing a glass substrate () includes preparing a disk-shaped glass blank having main surfaces () and an outer circumferential end face (), and irradiating the disk-shaped glass blank with a laser beam (L) along a distance longer than one lap of the outer circumferential end face () of the disk-shaped glass blank.

Magnetic disk-use glass substrate manufacturing method, discoidal glass substrate, glass substrate, and magnetic disk-use glass substrate

Chamfering processing for chamfering an edge face of a disk-shaped glass plate includes a step of disposing the glass plate such that a portion of the glass plate is disposed in a heating space for heating the glass plate and the remaining portion is disposed outside the heating space; and a step of softening a portion of the edge face of the glass plate by irradiating a circumferential portion of the edge face with a laser beam outside the heating space while rotating the glass plate in one direction around the center of the glass plate, and heating the softened portion of the edge face that has reached the heating space through the rotation.

Method for manufacturing glass plate, method for manufacturing magnetic-disk glass substrate, and method for manufacturing magnetic disk

A method for manufacturing a disk-shaped glass plate in which shape processing is performed on an edge surface of the glass plate includes processing the edge surface into a target shape by irradiating the edge surface with a laser beam while moving the laser beam relative to the edge surface in a circumferential direction of the glass plate. A cross-sectional intensity distribution of the laser beam with which the edge surface is irradiated is a single mode, and W>Th holds true and Pd×Th is in a range of 0.8 to 3.5 [W/mm] when a width of luminous flux of the laser beam in a thickness direction of the glass plate at an irradiation position of the edge surface is W[mm], a thickness of the glass plate is Th [mm], and a power density of the laser beam is Pd.

Method for manufacturing glass plate, method for chamfering glass plate, and method for manufacturing magnetic disk

A magnetic-disk substrate according to an embodiment includes two main surfaces and an outer circumferential edge surface. In the magnetic-disk substrate, the outer circumferential edge surface includes two chamfered surfaces that are respectively connected to the main surfaces, and a side wall surface that is curved and extends to protrude outward between the two chamfered surfaces. The side wall surface has a radius of curvature of 1100 μm or more on a cross-section of the magnetic-disk substrate extending along a plate thickness direction of the magnetic-disk substrate.

Magnetic disk substrate, magnetic disk, annular-shaped substrate, and method for manufacturing magnetic disk substrate

A method for manufacturing a glass substrate including an opening includes forming lines of inner and outer circumferential portions irradiated with a laser beam along substantially concentric circles in a surface of a glass blank, 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 from each other by heating the portion on the outer side of the line of the outer circumferential portion with radiant heat, 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 from each other by heating the portion on the outer side of the line of the inner circumferential portion with radiant heat.

Method for manufacturing glass substrate and method for manufacturing magnetic disk

A glass blank is cut out from a glass plate by forming a crack starting portion inside the glass plate by moving a first laser beam relative to the glass plate such that a focal position of the laser beam is located in an inner portion of the glass plate in its thickness direction and the focal position forms a circle when viewed from a surface of the glass plate, then causing cracks to develop from the crack starting portion toward main surfaces of the glass plate, and splitting the glass plate to separate, from the glass plate, a glass blank that includes a separation surface having an arithmetic average surface roughness Ra smaller than 0.01 μm and a roundness not larger than 15 μm. Thereafter, main surfaces of the glass blank are ground or polished.

Method for manufacturing disk-shaped glass blank and method for manufacturing glass substrate for magnetic disk

A method for manufacturing an annular glass plate that has an outer circumferential edge surface, an inner circumferential edge surface, and a thickness not larger than 0.6 mm includes processing for manufacturing an annular glass plate by irradiating each of the outer circumferential edge surface and the inner circumferential edge surface of an annular glass blank with a laser beam to melt the outer circumferential edge surface and the inner circumferential edge surface and form molten surfaces such that the molten surfaces in the outer circumferential edge surface and the inner circumferential edge surface each have an arithmetic average surface roughness Ra not larger than 0.1 μm, and the surface roughness of the molten surface in the inner circumferential edge surface becomes larger than the surface roughness of the molten surface in the outer circumferential edge surface.

Method for manufacturing annular glass plate, method for manufacturing glass substrate for magnetic disk, and method for manufacturing magnetic disk

A magnetic-disk glass substrate contains an alkaline earth metal component as a glass composition and includes a pair of main surfaces, and an outer circumferential side edge surface that is a mirror surface. The outer circumferential side edge surface includes a surface having a roughness percentage of 40% or more and 68% or less when a bearing ratio of a roughness cross-sectional area is 50% in a bearing ratio curve of roughness cross-sectional areas obtained when a surface roughness of the outer circumferential side edge surface obtained after the outer circumferential side edge surface is etched by 2.5 &#x3bc;m is measured. A glass transition point of the glass composition that constitutes the magnetic-disk glass substrate is 700&#xb0; C. or more. The glass composition that constitutes the magnetic-disk glass substrate is alkali-free glass.

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Hung Yen Province, Vietnam

Shuhei Azuma