System and method for molding plastic gear suppressing shrinkage
AssigneeRicoh Company, Ltd.
InventorYutaka Fukuchi
Life of this patent
Estimating the term…
Abstract
A gear molding method for molding a plurality of plastic gears having a different number of ribs without changing costly gates uses a mold having a prescribed gear shape including a prescribed number of grooves substantially radially arranged in the mold. A prescribed number of gates is provided for pouring molten plastic into the mold. When a plastic gear is molded and separated from the mold, a prescribed number of grooves are additionally cut at a middle angular position between each of the pair of neighboring grooves without changing the gates. Then, another gear having increased number of ribs is molded using the same gates.
Claims6
A gear molding method, comprising the steps of:
- providing a mold having a prescribed gear shape;
- providing a prescribed number of substantially radial grooves on the mold;
- providing a prescribed number of gates for pouring molten plastic into the mold including the prescribed number of grooves;
- molding a gear;
- separating the mold;
- ejecting the gear;
- additionally providing a prescribed number of grooves at angular positions between each of neighboring ones of the grooves without changing the gates;
- and
- molding another gear using said mold.
A gear molding method, comprising the steps of:
- providing a mold having a prescribed gear shape having a constant thickness in a gear bottom;
- providing a prescribed number of substantially radial grooves on the mold;
- providing a prescribed number of gates for pouring molten plastic into the mold including the prescribed number of grooves;
- molding a gear;
- providing a prescribed number of pins for ejecting the gear from the mold, each of said prescribed number of pins having a diameter smaller than a thickness of the gear bottom;
- and
- pushing and ejecting the gear by engaging the prescribed number of pins with the bottom of the gear.
A gear molding system, comprising:
- a mold configured to have a prescribed gear shape, said gear shape including a prescribed number of substantially radial grooves on the mold;
- a prescribed number of gates for pouring molten plastic into the mold including the prescribed number of grooves;
- a separating device configured to separate the mold;
- an ejecting device configured to eject the gear from the mold;
- and
- an additionally cutting device configured to additionally cut a prescribed number of grooves at angular positions between each of neighboring ones of the grooves without changing the gates.
A gear molding system, comprising:
- a mold configured to have a prescribed gear shape having a constant thickness in a gear bottom;
- a cutting device configured to cut a prescribed number of substantially radial grooves on the mold;
- a prescribed number of gates configured to pour molten plastic into the mold including the prescribed number of grooves;
- and
- a prescribed number of pins configured to eject the gear from the mold, each of said prescribed number of pins having a diameter smaller than the thickness of the gear bottom.
Dependencies are inferred from the claim text.