Rim rolling method, preforming roller die used for the method, and method of manufacturing brake shoe

摘要

The present invention provides a rim rolling method in which slotting can be correctly performed at an arbitrary position in the thickness direction of an outer peripheral face of a blank. A preforming roller die 7 is prepared in which a groove 8 is formed in an outer peripheral face 7a in the circumferential direction, and a groove forming blade portion 9 is protruded in the circumferential direction on an inner bottom portion of the groove 8. A preforming process is performed in which the groove 8 and the groove forming blade portion 9 of the preforming roller die 7 are pressed against an outer peripheral portion 10 of a disk-like metal blank 1, to form an outer peripheral groove 11 in the whole outer peripheral portion of the blank 1 by the groove forming blade portion 9. Thereafter, an expandingly forming roller die 12 in which an expanding blade portion 13 is protruded in the circumferential direction on an outer peripheral face 12a in the circumferential direction is pressed at the expanding blade portion 13 against the outer peripheral groove 11 of the blank 1, whereby rims 15a, 15b are expandingly formed while slotting the outer peripheral portion 10 of the blank 1 into two parts in the thickness direction.