Abstract: An apparatus for polishing an edge surface of a glass substrate for magnetic recording media. The apparatus includes a grindstone including abrasive grains mixed with a resin. The grindstone is configured to polish at least the edge surface of the glass substrate. The grindstone has a reentrant groove with a bottom surface and sidewall surfaces such that the bottom surface of the reentrant groove contacts the edge surface of the glass substrate and the sidewall surfaces of the reentrant groove contacts chamfered sidewalls of the glass substrate. The reentrant groove and sidewall surfaces are formed in the resin of the grindstone by pressing the glass substrate into the resin of the grindstone with a force higher than a pressing force during polishing.

Abstract: An apparatus for polishing an edge surface of a glass substrate for magnetic recording media. The apparatus includes a grindstone including abrasive grains mixed with a resin. The grindstone is configured to polish at least the edge surface of the glass substrate. The grindstone has a reentrant groove with a bottom surface and sidewall surfaces such that the bottom surface of the reentrant groove contacts the edge surface of the glass substrate and the sidewall surfaces of the reentrant groove contacts chamfered sidewalls of the glass substrate.

Abstract: To provide an apparatus for polishing an edge surface of a glass substrate for magnetic recording media and a process for producing a glass substrate for magnetic recording media, whereby with respect to a glass substrate to be used as a substrate for a hard disk, the quality and productivity can be improved without requiring extra effort. In a process for practically producing a hard disk by using a glass substrate 2, the arithmetic average roughness (Ra) required for the outer edge surface of the glass substrate is at most 100 nm. With the roughness of this level, highly productive mechanical polishing by a grindstone is possible. Further, since such mechanical polishing is possible, the productivity can be increased by adopting sheet treatment. Further, by stabilizing the processing margin by employing a grindstone 4 made of resin, variations in the dimensional precision in the individual glass substrates can be minimized.

Abstract: The invention provides a technique which is effective for reusing a hydrated fluid waste product or the like. A fluid raw material containing a water content and a solid content is changed to a lightweight solidifying material while being carried to a destination place, by adding or removing the water content by a gravity adjusting apparatus (1) so as to adjust gravity, next adding and mixing a solidifying material by means of a first pipe-type mixer (4), and next adding and mixing a lightening material by means of a second pipe-type mixer (5).

Abstract: A shield tunneling method of excavating a tunnel with an optional cross section by rotating a center cutter about an axis extending in the direction of propulsion and revolving a planetary cutter around the axis so as to excavate the region between the profile of excavation by the center cutter and the desired profile of excavation. A machine for practicing the method includes a center cutter supported by the body of the machine so as to be rotatable about an axis extending in the direction of propulsion of the body, a rotary body rotatable about the same axis as the center cutter, a planetary cutter supported by the rotary body so as to be movable radially of the rotary body, and operating device for moving the planetary cutter in the radial direction to permit the planetary cutter to revolve along a locus during the rotation of the rotary body so that the planetary cutter excavates the above-mentioned region.