MANUFACTURE OF OPTICAL RECORDING DRUM

摘要

PURPOSE: To obtain an optically smooth and concentric circular surface by forming a layer having smoothness of the level obtainable only by ordinary coating or intricate grinding and polishing treatments on the surface of a cylindrical drum, to eliminate the ellipticity or non-roundness at a large scale by the cylindrical surface and to eliminate the cause for the fluctuations of the other surface admitted with the conventional drums produced by mass production. CONSTITUTION: In the process for producing the rotary recording drum 12 by using a single cylindrical mold rotating around the axial line direction of a central mold shaft, a mold 32 is first rotated around the revolving axial line and a metered fluid material is charged into a mold cavity. This fluid material is radiated centrifugally toward the mold wall and forms the cylindrical layer of the fluid material having the inner flank of the concentric and smooth circular shape equidistant from the revolving axial line described above. Next, a surface forming material composed of epoxy having the density lower than the density of the fluid material is charged into the mold cavity adjacently to the inner flank of the fluid material. This surface forming material is cured.