초록 ▼

Method and apparatus for lens thickness adjustment in injection molding of thermoplastic vision-corrective spectacle lenses without manual addition or removal of shims, of inserts or of any other mold part. Thickness adjustment can be made quickly between molding cycles with a simple manual setting

Method and apparatus for lens thickness adjustment in injection molding of thermoplastic vision-corrective spectacle lenses without manual addition or removal of shims, of inserts or of any other mold part. Thickness adjustment can be made quickly between molding cycles with a simple manual setting and locking step while the lens mold is kept at very hot operating temperatures, yet with minimal risk of burning the operator. A rotatable adjustment head is mounted externally onto the mold's operator side, and manually-driven rotation turns a threaded screw which engages a mechanical assembly which produces an axially perpendicular motion which in turn drives forward or back the settable position of an optically polished insert within the lens mold's cavity. Preferably, this manually-driven rotation turns a worm gear mechanism which rotates a threaded male shaft within a mated threaded female bore axially perpendicular to the parting line. The mated threaded shaft and bore are part of a loadbearing support assembly joined to an optical insert which is one of an opposing pair within a lensmold cavity. The shaft's rotational displacement produces an axial change in the separation distance of these opposing inserts, and thereby a change in lens thickness. Alternatively, a toggle mechanism replaces the worm gear, shaft and bore assembly.

대표청구항 ▼

[ We claim:] [1.] An injection mold apparatus for molding thermoplastic spectacle lens, said injection mold having a mechanism for determining a thickness of said lens by precisely adjusting and then locking into a fixed position said mechanism, the apparatus comprising:a. said injection mold having

[ We claim:] [1.] An injection mold apparatus for molding thermoplastic spectacle lens, said injection mold having a mechanism for determining a thickness of said lens by precisely adjusting and then locking into a fixed position said mechanism, the apparatus comprising:a. said injection mold having at least one mold cavity formed between two mold halves which open and close about a parting line, with each mold half housing at least one of an opposing pair of optically polished mold inserts, each of said inserts having a surface facing into said mold cavity and each of said inserts having a back surface which faces away from said mold cavity,said insert optically polished surface facing into said mold cavity being of specified surface curvature and said opposing pair of mold inserts thereby forming partforming surfaces of said mold cavity,said insert back surface being mechanically supported against a substantially mating face of a loadbearing support assembly which is capable of transmitting forces from said insert to a clamping platen of a injection molding machine, such that melt pressures which are exerted upon said partforming surfaces are ultimately supported by a countervailing clamping force applied by said injection molding machine;b. an mated combination of a bore within said loadbearing support assembly, said bore having a threaded female surface which is coupled to a rotary threaded male shaft,wherein a rotary displacement of said shaft causes a predetermined displacement of said insert back surface being mechanically supported against said substantially mating face of said loadbearing support assembly, so as to make proportional the rotary displacement of said shaft to a corresponding change in the thickness of said lens;c. means for adjustment of said thickness of said lens, said means for adjustment being capable of being moved to a plurality of positions when the mold is not filled with plastic;d. means for mechanical linkage of motions of said mated combination of said shaft operating within said bore, in response to motions of said means for adjustment, by which motions a specified amount of rotary displacement of said shaft is produced when the mold is not filled with plastic; ande. means for locking said mated combination of said shaft operating within said bore, after said adjustment is made when the mold is not filled with plastic;such that there is substantially no slippage between said mated combination of said shaft operating within said bore during subsequent injection molding cycles.