Assembled multi-layer shafts

A method of making a hollow shaft having multiple functional elements arranged along the axis of an inner shaft tube is provided. Several multiple shafts equipped with functional elements may be joined by expansion using probes inserted into the shafts and connected to a high pressure generator. In addition, a method of providing functional elements to an inner tube wherein the individual non-round functional elements have annular projections concentric to the base circle is provided, where the internal diameter of the functional elements is slightly larger than the external diameter of the shaft tube. The functional elements have an annular region on their lateral edges of approximately half the wall thickness that complements the adjacent non-round functional element to achieve a full wall thickness and the annular projections are produced by re-formation of the profile tube. The present invention permits manufacturer of, for example, multiple cams, while retaining torsional stiffness of the cam shaft and allowing for close placement of the functional elements with respect to one another.