Abstract: This invention provides a manufacturing method of a molded glass object in which generation of defects such as dents and wrinkles due to catching of ambient gas between a molten glass drop and an upper mold is restrained in the case of manufacturing a molded glass object by press-molding of a dropped molten glass drop, and a manufacturing method of an upper mold for the manufacturing method of a molded grass object. A molten glass drop is press-molded by use of an upper mold having been subjected to a roughening treatment to roughen the surface on the molding surface to compress the molten glass drop.

Abstract: A magnetic recording medium includes, in a main surface of a glass substrate on which a magnetic recording layer is formed, a plurality of annular first thermally-conductive regions having a larger thermal conductivity than the glass substrate that are provided concentrically with the glass substrate. The first thermally-conductive regions are each provided so that it extends across a plurality of tracks. The first thermally-conductive region has a radial width larger than a depth, from the main surface, of the first thermally-conductive region.

Abstract: In one aspect, there is provided a process for manufacturing a lower mold for receiving a falling molten glass droplet, in which without narrowing the option for material for a lower mold, any occurrence of air retention can be favorably prevented and a lower mold excelling in durability can be obtained. The process comprises the film forming step of forming a coating layer on a base material and the surface roughening step of roughening the surface of the coating layer. Preferably, the coating layer contains at least one element selected from among chromium, aluminum and titanium.

Abstract: A magnetic recording medium includes, in a main surface of a glass substrate (1G) on which a magnetic recording layer (20) is formed, a plurality of annular first thermally-conductive regions (101) having a larger thermal conductivity than the glass substrate (1G) that are provided concentrically with the glass substrate (1G). The first thermally-conductive regions (101) are each provided so that it extends across a plurality of tracks (T). The first thermally-conductive region (101) has a radial width (W) larger than a depth (H), from the main surface, of the first thermally-conductive region (101).

Abstract: This invention provides a molding die in which increase of the surface roughness due to crystal growth of chromium oxide is restrained, and thereby allowing long term use without deteriorating surface roughness of a glass gob or a molded glass article. The invention also provides a method for manufacturing the molding die, a glass gob, and a molded glass article. A molding die is provided with a substrate having a molding surface and protective film containing chromium formed thereon, and the protective film has the X-ray diffraction peak intensity of (110) plane of chromium higher than the X-ray diffraction peak intensity of (200) plane.

Abstract: A substrate protective film composed of chromium metal is formed on a molding surface of a mold base material composed of cemented carbide. The substrate protective film is oxidized by heat treatment or ion implantation, so that a surface protective film composed of chromium oxide is formed. A pair of molds having such a constitution are prepared. Softened glass is pressed between the surface protective films of the paired molds, so that optical glass elements are molded.

Abstract: Disclosed is a lower molding die that can well prevent the occurrence of an air bubble without narrowing the range of choice for materials for the lower molding die and, at the same time, is highly durable. Also disclosed is a method for manufacturing a molding die for molding molten glass droplets. The method comprises a step of machining a molding surface of the molding die, a polishing step of polishing the molding surface to an arithmetic average roughness (Ra) of not more than 10 nm after the machining step, a step of forming at least one cover layer on the surface of the molding surface after the polishing step, and a step of roughening the surface of the cover layer formed on the molding surface.

Abstract: Disclosed is a lower molding die for receiving a molten glass droplet which is dripped. A cover layer is formed on a substrate with an intermediate layer therebetween, and a roughening process is performed on the surface of the cover layer in order to increase arithmetic average roughness Ra. The surface of the cover layer subjected to the roughening process has an arithmetic average roughness Ra of 0.01 ?m or more, and an average length RSm of a roughness curvilinear element of 0.5 ?m or less.

Abstract: This invention provides a method for manufacturing a molding die having excellent durability, with which durability film peeling and air bubbles are effectively reduced. A molding surface having a predetermined shape is formed on a substrate, and a cover layer is deposited on the molding surface by a sputtering method which cover layer is then roughened by etching. In the above method, the cover layer is deposited with the substrate held by a substrate holding member which is rotated around a predetermined rotation axis to vary the relative position between a sputtering target and the substrate holding member in such a way that the angle between the normal line of the surface of the sputtering target and the rotation axis is temporarily varied.

Abstract: Provide is a method for manufacturing a glass molding die in which deformation of a molding die in a process after machining is restrained without increased wear of a bit, and a method for manufacturing a molded glass article utilizing the glass molding die. A plated layer made of Ni—P plating is formed on the surface of a substrate, a rough machining is performed on the plated layer to form a shape similar to the desired final shape, the plated layer is then subjected to a thermal treatment, and finally finish machining is performed to form the desired final shape.

Abstract: This invention provides a molding die in which increase of the surface roughness due to crystal growth of chromium oxide is restrained, and thereby allowing long term use without deteriorating surface roughness of a glass gob or a molded glass article. The invention also provides a method for manufacturing the molding die, a glass gob, and a molded glass article. A molding die is provided with a substrate having a molding surface and protective film containing chromium formed thereon, and the protective film has the X-ray diffraction peak intensity of (110) plane of chromium higher than the X-ray diffraction peak intensity of (200) plane.

Abstract: In one aspect, there is provided a process for manufacturing a lower mold for receiving a falling molten glass droplet, in which without narrowing the option for material for a lower mold, any occurrence of air retention can be favorably prevented and a lower mold excelling in durability can be obtained. The process comprises the film forming step of forming a coating layer on a base material and the surface roughening step of roughening the surface of the coating layer. Preferably, the coating layer contains at least one element selected from among chromium, aluminum and titanium.

Abstract: This invention provides a manufacturing method of a molded glass object in which generation of defects such as dents and wrinkles due to catching of ambient gas between a molten glass drop and an upper mold is restrained in the case of manufacturing a molded glass object by press-molding of a dropped molten glass drop, and a manufacturing method of an upper mold for the manufacturing method of a molded grass object. A molten glass drop is press-molded by use of an upper mold having been subjected to a roughening treatment to roughen the surface on the molding surface to compress the molten glass drop.

Abstract: A substrate protective film composed of chromium metal is formed on a molding surface of a mold base material composed of cemented carbide. The substrate protective film is oxidized by heat treatment or ion implantation, so that a surface protective film composed of chromium oxide is formed. A pair of molds having such a constitution are prepared. Softened glass is pressed between the surface protective films of the paired molds, so that optical glass elements are molded.

Abstract: A die for forming an optical element, comprising: (i) a base member having a base surface which comprises a foundation area including a die surface to form an optical surface of the optical element and a peripheral area provided around the foundation area; (ii) a first layer covering both of the foundation area and the peripheral area and removable by being dissolved in a processing solution; and (iii) a second layer covering a part of the first layer corresponding in position to the foundation area so that a remaining part of the first layer corresponding in position to the peripheral area is not covered by the second layer.

Abstract: A glass material is press-molded by an upper die and a lower die in a closed space, so that an optical element is manufactured. A temperature variation of an atmosphere in the closed space is controlled within ±0.5° C. The glass material is dropped from a nozzle of a fusion furnace onto the lower die. A dropping space between the nozzle and the lower die which receives molten glass droplets is surrounded by an enclosure. Further, a die moving space in which the lower die moves from the dropping position where the molten glass is dropped to a molding position where the upper die stands by is enclosed by another enclosure. The molten glass dropped from the nozzle of the fusion furnace is press-molded in an atmosphere of stable temperature, so that optical glass elements with less variation can be manufactured.

Abstract: A substrate protective film composed of chromium metal is formed on a molding surface of a mold base material composed of cemented carbide. The substrate protective film is oxidized by heat-treatment or ion implantation, so that a surface protective film composed of chromium oxide is formed. A pair of molds having such a constitution are prepared. Softened glass is pressed between the surface protective films of the paired molds, so that optical glass elements are molded.

Abstract: A die for forming an optical element, comprising: (i) a base member having a base surface which comprises a foundation area including a die surface to form an optical surface of the optical element and a peripheral area provided around the foundation area; (ii) a first layer covering both of the foundation area and the peripheral area and removable by being dissolved in a processing solution; and (iii) a second layer covering a part of the first layer corresponding in position to the foundation area so that a remaining part of the first layer corresponding in position to the peripheral area is not covered by the second layer.