| 摘要 |
A spherical core type lens grinding device (1) performs an operation wherein a dish-shaped grindstone (8) provided with a spherical grindstone surface (8a) which is equipped with diamond abrasive grains, is pressed against a surface-to-be-ground (7a) of a lens blank (7) to be ground, and wherein the dish-shaped grindstone (8) is rotated and is simultaneously swung, resulting in said surface-to-be-ground (7a) being ground to a spherical surface. In an initial-stage grinding process, grinding is performed at first processing pressure and first rotational speed. In an intermediate-stage grinding process, grinding is performed at second processing pressure and second rotational speed. In a last-stage grinding process, grinding is performed at third processing pressure and third rotational speed. The second processing pressure is a pressure at which the spherical grindstone surface (8a) can bite into the lens blank (7). The biting amount of the dish-shaped grindstone (8) is obtained from the hardness of the lens blank (7) and the contact area between the surface-to-be-ground (7a) and the spherical grindstone surface (8a). The second processing pressure is calculated from the biting amount thus obtained. A coarse grinding process and a precision grinding process are unified into a single process. Therefore, the surface of the lens blank can be ground to a spherical surface by using only a dish-shaped grindstone used for precision grinding. |
