Patent ID: 8875397

Claim:
A vehicle wheel manufacturing method, the vehicle wheel including: front and back flange portions and bead seat portions for supporting a bead of a tire; a well portion in a front-back direction which is formed between the front and back bead seat portions; a rim portion in which in an annular outer rim portion having the front flange portion and the front bead seat portion formed therein and/or in an annular inner rim portion having the back flange portion and the back bead seat portion formed therein, a rim cavity portion is circumferentially formed along a wheel circumferential direction, an internal space of the rim cavity portion is defined by a plurality of partition wall portions in the wheel circumferential direction to form sound absorbing spaces for damping a sound wave in a tire-internal space which is sealed by the rim portion and the tire mounted on the rim portion; and a disc portion coupled with an axle, the method comprising: a casting step of circumferentially forming, in a portion adjacent to at least either one of the front and back sides, a ring-shaped wall portion which protrudes outward in a radial direction from an outside surface of the well portion of the rim portion and forming the plurality of partition wall portions at regular intervals in the wheel circumferential direction between the ring-shaped wall portion and the flange portion; a bending process step of bending the ring-shaped wall portion of the rim portion toward either one of the flange portions, bringing an inside wall surface of the ring-shaped wall portion into contact with an outside end surface of each of the partition wall portions, and bringing the outer circumferential end portion of the ring-shaped wall portion into contact with the flange portion in the wheel circumferential direction; a joining step of joining the outer circumferential end portion of the bent ring-shaped wall portion with the flange portion entirely in the wheel circumferential direction to form the bead seat portions and the rim cavity portion and to produce the sound absorbing spaces parted by each of the partition wall portions; a heat treatment step of performing a prescribed heat treatment; and a hole process step of drilling a communication hole in the bent ring-shaped wall portion, the communication hole communicating the sound absorbing spaces with outside; the steps being sequentially performed, wherein before the bending process step, a separation groove having a curved shape groove bottom surface at a prescribed depth is formed in a width direction of each of the partition wall portions between the ring-shaped wall portion and each of the partition wall portions, and by bending the ring-shaped wall portion toward the flange portion in the bending process step, communication gaps which communicate the adjacent sound absorbing spaces with each other are defined by the separation groove between the inside wall surface of the ring-shaped wall portion and the outside end surfaces of the partition wall portions.