A method of manufacturing a washer capable of improving a material yield is provided. The method includes: a preparation step of preparing a longitudinal member which includes an upper crest portion and a lower crest portion formed on at least one of an upper surface and a lower surface of the longitudinal member, and an upper valley portion and a lower valley portion continuous to the upper crest portion and the rower crest portion in the right-left direction, respectively, the upper valley portion and the lower valley portion provided with projections, respectively; and a deformation step of deforming the longitudinal member such that the upper surface and the lower surface are arcuate as viewed in the direction from the front to the rear.

A nut and washer assembly includes a washer unit that is coupled to a nut. The washer unit includes a housing and a washer that is disposed within a sleeve on an inner surface of the housing such that the washer is inseparable from and axially rotatable with respect to the housing. The housing is attached to the nut such that the washer captured within the housing of the washer unit and the nut operate as a single unit.

A washer that includes: an inner peripheral face formed in an arc shape; an outer peripheral face formed in an arc shape concentric with the inner peripheral face on a radially outer side of the inner peripheral face; and outer peripheral cut-out portions (such as a left outer peripheral cut-out portion and a right outer peripheral cut-out portion) formed at positions of the outer peripheral face corresponding to end portions (a first end portion and a second end portion) of the inner peripheral face to have the same shapes as outside shapes of the corresponding end portions of the inner peripheral face.

A washer that includes: an inner peripheral face formed in an arc shape; an outer peripheral face formed in an arc shape concentric with the inner peripheral face on a radially outer side of the inner peripheral face; and outer peripheral cut-out portions (such as a left outer peripheral cut-out portion and a right outer peripheral cut-out portion) formed at positions of the outer peripheral face corresponding to end portions (a first end portion and a second end portion) of the inner peripheral face to have the same shapes as outside shapes of the corresponding end portions of the inner peripheral face.

The present disclosure relates to a terminal part for a cylindrical secondary cell. The terminal part comprises a shaft configured to extend axially through a casing of the secondary cell, wherein a first end of the shaft is configured to provide an electrical connection with an electrode roll in the secondary cell; and a head arranged at a second end of the shaft, configured to form an external terminal for the cylindrical secondary cell. The shaft comprises a ridged shaft portion on a lateral surface of the shaft, wherein said ridged shaft portion comprises at least one ridge extending around the lateral surface of the shaft.

The present disclosure relates to a terminal part for a cylindrical secondary cell. The terminal part comprises a shaft configured to extend axially through a casing of the secondary cell, wherein a first end of the shaft is configured to provide an electrical connection with an electrode roll in the secondary cell; and a head arranged at a second end of the shaft, configured to form an external terminal for the cylindrical secondary cell. The shaft comprises a ridged shaft portion on a lateral surface of the shaft, wherein said ridged shaft portion comprises at least one ridge extending around the lateral surface of the shaft.