| 摘要 |
PURPOSE:To attempt to prevent unbalance of amt. of fed resins among a plurality of cavities by starting a decreasing operation of a cavity vol. when injection of a resin proceeds and before the whole amt. of a measured resin in advance is injected and controlling an injection pressure and an amt. of injection so as to get rid of unfilled part or excess filling during the vol. of the cavity is decreased to a vol. wherein a vol. of molding shrinkage is estimated from a vol. of a product. CONSTITUTION:Choosing the time when a resin flows in cavities 32 and 33 in such a degree that no welding occurs even the vol. of the cavities 32 and 33 are decreased, a decreasing operation of the vol. of the cavities 32 and 33 is started. When a position sensor 35 detects that the resin corresponding to 95% of the premeasured resin has been injected, a clamping cylinder 3 is controlled in such a way that the vol. of the cavities 32 and 33 reaches a vol. corresponding to 110% of a vol. of a lens to be molded. In addition, an injection pressure of the resin by means of a plunger 28 is lowered to 30kgf/cm<2>. When the vol. of the cavities 32 and 33 reaches 105% of the vol. of the lens to be molded, filling in the cavity 33 is thoroughly completed. |
