Deformed element pipe for hydraulic bulging, hydraulic bulging device using the element pipe, hydraulic bulging method using the element pipe, and hydraulic-bulged product

摘要

A profile element pipe for hydraulic bulging of the present invention has a peripheral length with an outer diameter gradually increasing or decreasing from one axial side toward the other thereof and has a parallel part formed on at least one end thereof. According to a bulging device and a bulging method using this profile element pipe, for example, even when a profile steel pipe having a cross sectional shape varying in the axial direction as in a tapered pipe is hydraulically bulged, a bulging in which an internal pressure loading and an shaft pressing are combined with each other can be performed to provide a larger expansion ratio than a conventional case and a joining and socket connection thereof to the other part can also be easily performed.