| 摘要 |
PROBLEM TO BE SOLVED: To ensure high rigidity and strength by forming an intermediate annular part between collars formed at the inner and outer peripheries of an annular steel plate, into hat-shaped cross section to enclose needle rollers, and specifying the minimum plate thickness of the bent corner part. SOLUTION: Collars 2, 3 formed by bending and folding are provided at the inner and outer peripheries of an annular thin steel plate blank. Hat-shaped cross section 4 is formed at an intermediate annular part between the collars 2, 3 and provided with pockets 5 equally spaced in a circumferential direction to enclose needle rollers 6. The minimum plate thickness of a bent corner part is to be 75% or more of material plate thickness, preferably 85% or more. In a manufacturing method, cross-sectional length and the cross-sectional radius- of-curvature of the bent corner part are preformed to be larger than product dimensions, and finish-forming of the cross section 4 is applied after forming annular bent step difference on both inner and outer peripheral sides to relax the concentration of tensile flexural deformation consequent to drawing, on the bent corer part. The strength of the bent corner part weakest as a strength component is therefore heightened to ensure a long service life.
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