| 摘要 |
PURPOSE:To enable the title device to eliminate a weld line of a plastic lens and reduce a power cost by shortening the time required for lens molding cycle, by a method wherein a minute groove is formed on the whole circumference or a part of the surface of a cavity of a mold for molding the lens by corresponding to the external circumferential surface or the surface close to the external circumference of the outside of the effective diameter of the lens. CONSTITUTION:A groove whose width is 5mum or narrower and depth is 5mum or deeper is formed in a meshy state through etching on a groove surface 1'a of a stationary insertion piece 5, a groove surface 3' of a movable mold 6 and a groove surface 2'a of a movable insertion piece 7. A minute groove is provided in the meshy state similarly on groove surfaces 5b, 7b of the stationary insertion piece 5 and movable insertion piece 7. Resin 9 entered into a cavity 9' through a gate 8 is met at a position of a weld line alpha, gas collected in a V notch beta of the weld line alpha is diffused into a space gammaof the bottom of the grooves of the surfaces 1'a, 2'a, 3' by an increase of a resin pressure and an exhaust action of a rotary pump 21. The gas arrives at a space 12 and ventilation hole 25 by passing through a connection of the space gamma of the bottom of the groove and a gap 26 between the groove surface 5b of the stationary insertion piece 5 and a stationary mold 4. The gas is discharged similarly at a gap 27 and space 13. |
