Mold for manufacturing a fiber reinforced polymer utility vault lid
A method of manufacturing a fiber reinforced composite material lid for an utility vault including mixing an unsaturated polyester thermosetting matrix in to a resin paste, compounding the resin paste into a fiber reinforced composite material, maturing the compounded fiber reinforced composite material, cutting the matured compound into a charge pattern, molding the charge pattern in a mold cavity of a heated mold under low pressure to form the lid and cooling and machining the lid. The mold includes a cavity die and a core die having a shear angle for interfacing the core die within the cavity die and a steam pot for heating the cavity die and the core die, wherein the lid is molded between the cavity die and the core die and removed from the mold by a lid ejection mechanism.
1. A mold for molding a fiber reinforced polymer
material utility vault lid comprising:
a cavity die having a mold surface;
a core die having a telescoping shear edge for interfacing the core die within the cavity die, wherein the fiber reinforced polymer material utility vault lid having a plurality of individual fibers within polymer material is molded between the cavity die and the core die; and
a lid ejection mechanism for removing the molded lid from the mold;
wherein the mold surface of the cavity die has a textured surface along the entire mold surface comprising a pattern of non-uniform spaced recesses extending into the mold surface of different sizes and depths and a plurality of protrusions of irregular height, size and shape, a protrusion of the plurality of protrusions being positioned between each recess and extends outwardly to engage and push the individual fibers of the fiber reinforced polymer material utility vault lid inwardly away from an upper surface of the lid to create a resin rich layer above the individual fibers along the upper surface of the lid during molding and preventing the individual fibers from reaching the upper surface of the lid.
2. The mold of claim 1 further comprising means for aligning the cavity die and the core die.
3. The mold of claim 2 wherein the means for aligning are alignment pins and bushings.
4. The mold of claim 1 wherein the telescoped shear edge provides for a gap between the core die and the cavity die to allow air to escape during a molding period.
5. The mold of claim 1 further comprising means to heat and control temperature of the cavity die and the core die.
6. The mold of claim 5 wherein the means to heat and control temperature is a steam pot including internal supports and a sealing plate.
7. The mold of claim 1 wherein the lid ejection mechanism are pins extending through the die core and actuated by a pin plate.
8. The mold of claim 7 wherein the pin plate is hydraulically actuated.
9. The mold of claim 1 where the cavity die further has a plurality of boss recesses for forming bosses on an upper surface of the lid.
10. The mold of claim 9 wherein the boss recesses are of varying depths.