| 摘要 |
When an inner ring of a driving-wheel supporting hub unit is fixed to a hub, a pressing die is displaced downward and an annular working surface at a lower end surface of the pressing die is pressed against a front end of a cylindrical portion over its whole periphery. Further, in this state, the pressing die is pressed downward toward the hub without rocking the pressing die relative to the hub. Thus, the cylindrical portion is plastically deformed radially outward along the working surface simultaneously over its whole periphery. By adopting this method, the operation of plastically deforming the cylindrical portion at the inner end of the hub to form a caulking portion, can be easily and performed accurately. Accordingly, the structure of the caulking portion forming apparatus can be simplified. |
| 主权项 |
1. A driving-wheel supporting hub unit comprising:
a hub, comprising: a flange for supporting a vehicle wheel at an axially outer end of the hub, a first inner ring raceway at an axially intermediate portion of the hub, and a first small-diameter stepped portion at an axially inner end of the hub, an outer diameter of the first small-diameter stepped portion being smaller than an outer diameter of the first inner ring raceway; an inner ring fitted to the first small-diameter stepped portion, the inner ring comprising: a second inner ring raceway formed at an outer circumferential surface of the inner ring, a large-diameter stepped portion comprising an inner diameter larger than a diameter of an axially intermediate portion of an inner circumferential surface of the inner ring, located at an axially inner end of the inner circumferential surface of the inner ring, a stepped surface located between the axially intermediate portion of the inner circumferential surface and the large-diameter stepped portion; an outer ring comprising: a first outer ring raceway facing the first inner ring raceway, and a second outer ring raceway facing the second inner ring raceway formed at an inner circumferential surface of the outer ring; and a plurality of rolling elements provided between the first and second inner ring raceways and the first and second outer ring raceways, respectively; wherein the stepped surface of the inner ring is held by a caulking portion formed by plastically deforming a cylindrical portion radially outward, the cylindrical portion being provided at the axially inner end of the hub, whereby the inner ring is coupled with and fixed to the hub and an axially inner end surface of the inner ring is made to project further axially inward than an axially inner end surface of the caulking portion, wherein a second small-diameter stepped portion is provided at an axially inner end of an outer circumferential surface of the cylindrical portion, an outer diameter of the second small-diameter stepped portion being smaller than the outer diameter of the first small-diameter stepped portion, and an axially outer end of the second small-diameter portion being located axially outward from a chamfered portion connecting the stepped surface of the inner ring and the axially intermediate portion of the inner circumferential surface of the inner ring, wherein the caulking portion is formed by pressing a pressing die axially toward the hub without rocking the pressing die with respect to the hub while an annular working surface provided in a portion of the pressing die is pressed against an axially inner end edge of the cylindrical portion over a whole periphery of the cylindrical portion, under temperature conditions of cold working, thereby plastically deforming the cylindrical portion radially outward along the working surface simultaneously over the whole periphery thereof, and wherein after forming, an outer circumferential edge of the caulking portion does not contact an inner circumferential surface of the large-diameter stepped portion. |
