Method for processing surface and apparatus for processing same

#1. Field of the Invention

#The present invention relates to a precision processing technology of a surface, especially a curved surface, which is capable of processing an optical object or device including the curved surface and a metal mold for molding the optical device precisely and efficiently while reducing variations of the processing precision.

#2. Description of the Prior Art

#FIG. 1 is a front view schematically showing a whole of a processing apparatus of polishing processing for a curved surface.

#FIG. 2 is a schematic view inflatedly showing a tolerance between a desired designed shape and a measurement result of a shape of a worked surface before processing (concretely, before polishing).

#FIG. 3 is a graph showing correction of a unit removal shape in Embodiment 1.

#Next, description will be made for embodiments with reference to the drawings.

#As shown in FIG. 1, in a polishing processing apparatus used in the present invention, a tool 1 having a rotating tire shape or a rotating spherical shape or alternatively having a shape composed of a part of such shapes is fixed to a spindle which also serves as a direct moving slide. A specified load is given to the direct moving slide 3 by a load generating mechanism unit 5, and the load is transmitted to the tool 1 to generate a load (thrust force) between the tool 1 and a worked surface of a work piece 7 or processed matter. The load is detected by a load sensor 4, and the load generating mechanism unit 5 is controlled by an unillustrated control unit (for example, a personal computer) so that the load can reach a specified value. In FIG. 1, reference numeral 2 denotes a shaft of the tool, reference numeral 6 denotes a column. The work piece 7 or processed matter can be subjected to so-called normal line control, in which a normal line of the worked surface is made to coincide with a direction where the load from the tool is loaded by an X-axis, a Y-axis and Z-axis and movements of a A-axis and a B-axis, which are parallel to the X-axis and the Y-axis, respectively. When the worked surface is a plane, processing for the same as it is may be considered by this normal line control. On the other hand, when the worked surface is a curved surface, processing for a surface obtained by developing the curved surface to an approximate plane may be considered. Here, a reason why the “approximate plane” is mentioned is described as follows. Specifically, when the worked surface has a cylinder shape, the worked surface can be developed into a plane. However, when the worked surface has other shapes, the worked surface cannot be developed into a perfect plane, and the developed surface becomes an approximate plane. In this case, a degree of developing a plane should be examined and decided in accordance with a target precision.

#A method for processing a worked surface of a work piece, according to the present invention comprises steps of processing a reference surface of a same material as a material of the work piece prior to processing the worked surface, obtaining a relationship between a processing condition and a removal quantity or removal depth of the material by the processing of the reference surface, correcting the relationship between the processing condition and the removal quantity or removal depth in the reference surface in accordance with a shape of the worked surface, and processing the worked surface of the work piece by use of the condition.