| 摘要 |
PROBLEM TO BE SOLVED: To suppress the rise of an assembling cost, to realize not only a long service life of working tools but also, the lightening of a load to be applied to assembling equipment and to prevent the crack of a cam lobe at expanding time. SOLUTION: In a mandrel 10 used for expanding the hollow shaft 3 of an assembling type cam shaft 1 fixedly composed of the hollow shaft 3 and the cam lobe 2 fixing them together by expanding the hollow shaft 3 inserted into the opening hole 2a of the cam lobe 2, this mandrel is projectively arranged from the peripheral surface of the mandrel body 11 formed as a columnar-state and provided with plurality of the projections 12 for expansion, pressing the inner peripheral wall 3a of the hollow shaft 3 at expanding time. Then, a portion of the projection 12 for expansion, in contact with at least the inner peripheral wall 3a of the hollow shaft 3 is covered with a diamond-like carbon 13 and also, the finished surface roughness is made to be≤0.2μm Ra. COPYRIGHT: (C)2005,JPO&NCIPI
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