Patent ID: 6136261
Filing Date: 2000-10-24
Classification: B29C,G03B

Abstract:
A method of producing disks for a photo film cassette, said photo film cassette being of the type including a spool core on which photo film is wound in a form of a roll; a cassette shell for containing said spool core in rotatable fashion; and a pair of said disks in each of which a bearing hole is formed, and which is secured to first and second ends of said spool core, for regulating edges of said photo film; said disk producing method comprising the steps, in the following order, of:partially masking an unheated sheet of thermoplastic synthetic resin with a mask plate formed as a single plate and having a plurality of openings in the shape of said disks, to provide a masked sheet portion at a rim portion of each opening and an unmasked sheet portion at a central portion of each opening; thensqueezing said masked sheet portion at a rim portion of each opening of said unheated sheet against said mask plate and retaining said mask while forming a disk-shaped portion in said sheet to avoid occurrence of wrinkles in said masked sheet portion; thenheating said unmasked sheet portion at the central portion of each opening to at temperature higher than a softening point of said sheet;heating said masked sheet portion at said rim portion of each opening to a temperature lower than a softening point of said sheet using heating passageways included in said mask plate;subjecting said unmasked sheet portion at said central portion of each opening by vacuum forming, or air-pressure forming, or vacuum/air-pressure forming in combination with vacuum forming and air-pressure forming, to form a plurality of disk-shaped portions in said sheet; andcutting said bearing hole and a contour of each of said disks in each said disk-shaped portions, to produce said disks.