{
  "$type": "site.standard.document",
  "description": "A cylindrical portion 10 is not quenched, and its hardness of a cylindrical portion 10 is set at Hv200 to 300. An average cross sectional area of the crystal particle in this portion is set to be within 0.03mm. Accordingly, when a caulking portion is formed by expanding the cylindrical portion 10b…",
  "path": "/patents/1111975",
  "publishedAt": "2001-06-27T00:00:00.000Z",
  "site": "at://did:plc:oql6ds5vnff4ugar6rruliwd/site.standard.publication/3mn3ohu7oxx5w",
  "tags": [
    "B21J9/025",
    "NSK LTD [JP]"
  ],
  "textContent": "A cylindrical portion 10 is not quenched, and its hardness of a cylindrical portion 10 is set at Hv200 to 300. An average cross sectional area of the crystal particle in this portion is set to be within 0.03mm. Accordingly, when a caulking portion is formed by expanding the cylindrical portion 10b to an inner ring 3 to a hub 2b made of carbon steel, cracks or the like are not formed in the resultant caulking portion.",
  "title": "Wheel-support rolling bearing unit and a method manufacturing the same"
}