Process and apparatus for manufacturing metallic hollow bodies with structural bulges

Abstract

For the most distinctive technical application purposes and particularly for forming tubular hollow bodies which require a structural bulge, for instance for employment in heat exchangers where a stronger turbulence of the heat exchanger mediums and with it an improved heat exchange is achieved through structural bulges on the exchanger tube. The manufacture such tubular hollow bodies with structural bulges by means of mechanical arrangements are extremely labor intensive and therefore costly. According to the invention, a magnetic impulse provides a hollow body (2) with the desired structural bulges (7) which correspond to a support core in a shrinking process, or by an expansion process when the support core is removed. The hollow body (2) to be formed is preferably tubular. It is processed through an opening (3) in a magnetic field concentrator (1) in intermittent steps, a profiled support core (4) at the end of a carrying bar (6) is placed in the interior of the hollow body (2) and preferable projects into the opening (3) in the magnetic field concentrator (1). After a first ring-shaped array of structural bulges (7) is formed, the hollow body (2) is moved in a next work step and twisted around its axis so that a further magnetic impulse will form another array of structural bulge around the hollow body. Additional arrays of structural bulges are shaped as the hollow body is gradually moved and magnetic impulses are generated.

Dependencies are inferred from the claim text.