SPECTACLES LENS MANUFACTURED FROM THERMOPLASTIC MATERIAL BY MOLDING, EJECTION AND DIP COATING Russian patent published in 2000 - IPC

FIELD: lenses for spectacles manufactured from thermoplastic material. SUBSTANCE: perimeter of female die is closed along parting line. The first height of female die equals sum of desired length of working stroke of compression and final thickness of molded article. Prior to injection, female die is partially filled to successively reduce the height in the second closing position. Closing force applied for exceeding the first elastic force is less than the second elastic force. Female die is fully filled by gradual reduction of its height to attain the third position. In this case, closing force exceeds the second elastic force. Molded article in female die is cooled to stable form of thermoplastic material. Female die height is maintained in the third closing position. After cooling molded article is ejected by weakening of closing force and opening of press mold along parting lin. Then article is coated by dipping and coat is hardened. The invention describes device for manufacture of such lenses and lenses manufactured by device with use of the method. EFFECT: improved surface finish of lenses with no burrs. 9 cl, 17 dwg