| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for efficiently producing a glass substrate for a magnetic recording medium, which is nearly free of edge sagging of the peripheral part of the surface of the substrate on the magnetic recording layer side and having flatness, homogeneity and few surface defects up to a part near the periphery of the surface of the substrate on the magnetic recording layer side. SOLUTION: Surface plates are attached to a double-ended polishing machine for a glass substrate for a magnetic recording medium, a abrasive board for reconditioning is held between the surface plates and the surface plates are turned in opposite directions, while supplying cooling water to polish the surface of the surface plates to <=30 μm in planarity. Abrasive cloths are stuck to the separate surfaces of the surface plates, as desired, the abrasive board is held between the abrasive cloths and the surface plates are turned together with the abrasive cloths, without having to supply cooling water to improve the plane accuracy of the surfaces of the abrasive cloths. The upper and lower surface plates are turned, together with the abrasive cloths without using the abrasive board, if appropriate and the upper and lower abrasive cloths are rubbed together to further improve the plane accuracy of the surfaces of the abrasive cloths. A glass substrate is polished repeatedly with the resulting grinding machine, to produce the objective glass substrate for a magnetic recording medium. |
