Method for producing a bellows with a cross section of elliptical, egg-shaped, shaped as two equal semicircles connected by two parallel straight lines, non circular ring or polygonal roundes form.

摘要

After a metallic cylindrical tube (1) is bulged to form a bellows with a circular cross section, this bellows is ovalized to form a bellows with an oval cross section. For this reason, an inexpensive round tube (cylindrical tube) can be used as the material for a bellows with an oval cross section and it is unneces­sary to use an expensive oval tube. Accordingly, a bellows with an oval cross section can be produced at low cost.