Patent attributes
A tube expanding device includes: a plurality of rollers each having a tapered portion whose diameter increases toward its front side; a cylindrical expander frame for freely rotatably holding the plurality of rollers on a concentric circle; a mandrel inserted in the expander frame so as to be freely slidable and rotatable relative to the expander frame, and having a tapered portion whose diameter decreases toward its front side, the tapered portion of the mandrel matching the tapered portion of each roller; a drive device coupled to the expander frame and rotating the expander frame; and a moving device for moving the mandrel forward and backward relative to the expander frame. By moving the mandrel forward relative to the expander frame, the tapered portion of the mandrel abuts on the tapered portions of the plurality of rollers and thereby expands a diameter of a circumscribed circle formed by the plurality of rollers.
