The present invention is intended to provide a method for manufacturing a resin gear with a core metal by which there is no reduction in strength even with gates allowing decrease in material costs such as pin gates in the molding die for injection molding.

The manufacturing method includes: gates at a primary molding step and gates at a secondary molding step are pin gates or the like. The number of the gates at the primary molding step and the number of the gates at the secondary molding step are plural and identical, and the gates are arranged circumferentially. Gate positions G21, . . . at the secondary molding step are circumferentially intermediate or nearly circumferentially intermediate between gate positions G11, . . . and weld positions W11, . . . adjacent to the gate positions G11, . . . in the primary molded article.

A manufacturing method of a resin molded member includes: an insert member molding step of building an insert member by stacking layers of a base resin containing continuous fibers by using a 3D printer; an aligning step of aligning the insert member in a cavity of an injection molding mold; and a resin portion molding step of molding a resin portion integrated with the insert member by filling an injection molding resin into the cavity, wherein the insert member is arranged on a surface of a weld portion by the resin portion molding step, and the continuous fibers in the insert member are oriented in direction crossing over the weld portion, the weld portion being formed in the resin portion.

[Object] To provide a technology capable of further improving the performance of an aromatic polyetherketone molded body.

[Solving Means] An aromatic polyetherketone molded body includes: a body portion; and a surface layer portion covering the body portion. An infrared absorption spectrum is obtained by measurement using an infrared spectrophotometer for both the body portion and the surface layer portion, the infrared absorption spectrum including a peak A and a peak B, the peak A appearing in a wavenumber range of 1295 to 1340 cm.sup.1, the peak B appearing in a wavenumber range of 1265 to 1295 cm.sup.1. A ratio A/B of strength A of the peak A to strength B of the peak B is higher in the surface layer portion than in the body portion.

A multi-stage helical gear manufacturing apparatus includes a first mold member, a second mold member, a large gear rotation core, a sleeve pin, a small gear rotation insert, and an insert pin. The second mold member moves the insert pin and the small gear rotation insert after the insert pin is caused to retreat in relation to the small gear rotation insert at the time of mold opening. The first mold member prohibits rotation of the large gear rotation core at the time of mold clamping, permits rotation of the large gear rotation core when the insert pin and the small gear rotation insert of the second mold member are moved at the time of mold opening, and causes the sleeve pin to advance toward the second mold member in relation to the plastic after the insert pin and the small gear rotation insert are separated from the plastic.

A gear formed of a resin containing a filler includes a plurality of recesses that are formed on a shaft-direction end surface of the gear, that spread from one side to the other side of respective straight lines extending outward in the radial direction of the gear from respective corresponding gate points, and that have asymmetric shapes with respect to the respective straight lines, where each of a plurality of points on the shaft-direction end surface corresponding one-to-one to a plurality of pin gates used to eject the resin during molding of the gear is taken as the gate point.

To align the orientation of resin fibers of a resin molded gear produced by insert molding and suppress the manufacturing cost of the resin molded gear.

The present invention includes a resin molded gear 1 and a gear-shaped insert 2. The insert 2 includes a web portion 21 and tooth portions 22. Each tooth portion 22 has tooth bottom portions 22a that oppose the tooth bottoms 12a of the resin molded gear 1 and a tooth tip portion 22c that opposes a tooth tip 12c of the resin molded gear 1. An annular first flow path 23 is formed in the surface of the web portion 21, and outlets 23a are provided on the outer edge of the first flow path 23 to allow molten resin 31 to flow out to the tooth bottom portions 22a.

A method for manufacturing a worm wheel including an inner wheel element including a side plate portion and a tubular eave portion, and an outer wheel element including a wheel tooth portion on an outer circumferential surface thereof, and coupled and fixed to the inner wheel element in a manner of covering a radially outer portion of the side plate portion and the eave portion, the method includes: molding the outer wheel element by disposing a mold around a radially outer portion of the inner wheel element, and feeding the molten synthetic resin from an annular or arc-shaped injection gate toward a pocket portion that is continuous over an entire circumference of a cavity present between an inner surface of the mold and a surface of the inner wheel element and that is present on a radially inner side of the eave portion.

A power transmission resin gear includes an annular resin part having, on an outer peripheral surface thereof, teeth of a gear. The annular resin part includes an annular inner resin member that covers an outer periphery of a core metal and an annular outer resin member that covers an outer periphery of the annular inner resin member. The annular inner resin member has a plurality of axially downgauged portions arranged at intervals in a circumferential direction. The annular outer resin member has filling portions respectively filling the axially downgauged portions and an axial surface covering portion that is located radially inward of a tooth side of the teeth and covers the filling portions.