Back to results
US 5,963,380 AGranted
Mold for inner gear and mold for cylindrical product with inner gear
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsHiroshi Nomura, Takamitsu Sasaki
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsHiroshi Nomura, Takamitsu Sasaki
Estimating the term…
A mold for a cylindrical product with an inner gear formed by injection molding is disclosed. The mold includes a plurality of sets of first and second inner slide cores each having inner molds with under-cut forming portions. The first and second inner slide cores move in a direction perpendicular to a center line of the inner cores at different velocities.
A mold for injection molding including a plurality of sets of first and second inner slide cores, said first and said second inner slide cores having inner molds with undercut forming portions adjacent to each other constituting one set of said first and said second inner slide cores, wherein said first and said second inner slide cores move in a direction perpendicular to a center line of said inner cores at different velocities from each other to open and close said inner cores, satisfying the formula:
A mold for injection molding for forming an element including an inner gear, said mold comprising:
Dependencies are inferred from the claim text.
From the US filing history. Foreign family members aren’t listed.
Drawings are temporarily unavailable. Open the PDF at USPTO
Toothed members; Worms: toothed wheels
Moulds: having screw-threaded mould walls
Moulds: with rotatable mould parts
For undercut articles: using expansible or collapsible cores
Term ended 19 Dec 2014 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a cylindrical product with an inner gear formed by injection molding, a mold for the cylindrical product, and a method of manufacturing the same.
2. Description of the Related Art
The present invention will be more apparent from the ensuing description with reference to the accompanying drawings wherein:
FIG. 1 is an exploded isometric view of a zoom lens barrel according to an embodiment of the present invention;
FIG. 2 is an enlarged isometric view of the rear portion of the zoom lens barrel shown in FIG. 1;
Embodiments of the present invention will be explained with reference to the drawings. A zoom lens barrel in a camera according to this embodiment is provided with a zoom lens system comprising of a front lens group L1 and a rear lens group L2. The focusing operation is carried out by the front lens group L1.
Referring to FIGS. 7 and 8, a fixed lens barrel 11 of the zoom lens barrel 9 secured to a camera body 10 to which the present invention is applied is provided with an inner cylinder 11a and an outer cylinder 11b. Rear ends of the inner cylinder 11a and the outer cylinder 11b in the direction of an optical axis X of the zoom lens system are connected to each other through the connecting wall 11c, and the front ends of the cylinders 11a and 11b are open. A rotation cylinder (i.e., cylindrical product) 12, which is inserted from the open end of the cylinders 11a, 11b, is rotatably mounted on the outer periphery of the inner cylinder 11a. Three straight guide grooves 11e, each extending in a direction parallel to the optical axis X are formed on the inner wall 11a. Only one of the three straight guide grooves 11e is shown in FIG. 8.
The rotation cylinder 12 as a cylindrical product to which the present invention is applied is made of a synthetic resin, and a spur gear 12a is integrally formed with the cylinder 12 on an outer periphery thereof as illustrated in FIG. 9. A fine thread 12b is integrally formed with the cylinder 12 at a tip of the outer peripheral portion thereof. On the inner wall of the rotation cylinder 12, three spiral lead grooves 12c which are parallel to one another and each inclined to the circumferential direction of the cylinder 12, an inclined spiral inner gear 12d parallel to the lead grooves 12c, and a spiral relief groove 12e are formed. The spiral relief groove 12e is formed in the vicinity of the gear 12d and is larger than the root circle of the inclined inner gear 12d in diameter and wider than the tooth width of the inner gear 12d.