Abstract:
A steel strip is fed and compressed between a driving roller and a compression roller to generate a stress greater than a yield stress in the steel strip and to elongate one periphery portion of the steel strip, which is on one side, more than the other periphery portion of the steel strip, which is on the other side, in a sending direction. The compression roller includes a first contact portion and a second contact portion. The second contact portion extends from an end of the first contact portion in the axial direction of the compression roller. The end of the first contact portion has an outer diameter less than an outer diameter of the second contact portion.
Abstract:
A protrusion forming device includes a holding portion holding an object that is be processed, a tool bit having a cutting portion capable of cutting an object held by a holding portion, and a drive portion capable of driving the tool bit. The tool bit is movable along a cut-in pathway so that the cutting portion is inserted into the object. The cutting portion is movable along a further-cut pathway so as to form a protrusion part that is cut in a linear shape and is connected to the object. The tool bit continuously contacts the protrusion part while moving along a forming pathway such that the protrusion part extends perpendicular to an outer surface of the object.