Patent ID: 7128468

Claim:
An assemblage for forming a hydrodynamic bearing, the assemblage comprising: a shaft, unit including a shaft having a cylindrical outer circumferential surface defining a first side of a radial hydrodynamic bearing section, and, orthogonal to the cylindrical outer circumferential surface, an end surface where a first joint surface is formed, and a disc member of diameter larger than that of said shaft and having a flat surface where a second joint surface is formed, for facing the end surface of the shaft to be joined and fixed thereto; a bearing member having a cylindrical inner circumferential surface opposing and rotatable relative to the cylindrical outer circumferential surface of said shaft, to define a second side of the radial hydrodynamic bearing section; an annular, axially protruding projection of diameter smaller than that of said shaft and configured so as to melt under a predetermined applied voltage, said projection provided on one of either said first or second joint surfaces; and a recess outer peripherally of diameter smaller than outside that of said shaft yet larger than that of said projection, and dimensioned so as to receive said projection as molten matter, said recess provided on one of either said first or second joint surfaces; wherein by bringing said first and second joint surfaces into contact and applying predetermined voltage across said shaft and said disc member, the said projection becomes molten matter and flows into said recess, bringing said end surface of said shaft and a said flat surface of said disc member into contact with each other and welding said shaft and said disc member together.