Helically wound metal tube making machine - has ribbed rotary mandrel with crescent section part casing for profiling bending and welding

摘要

The machine makes metal tubes from spirally wound, ribbed and welded metal strip. A single rotating mandrel (2) is used for the bending, the profiling, and the welding, so that the machine is lightweight and readily produces large diameter tube. The bending and profiling operations may take place simultaneously at a single post, deforming plain strip (10) into a winged 'U' section whilst bending it into longitudinal spirals. A curved guide (1) with a tapered rib presses the strip (10) between two adjacent circumferential ribs (6) of the mandrel. The deformed strip automatically advances along the mandrel and moves onto a crescent shaped former (8). This has an inside diameter equal to the external diameter of the mandrel (2) and houses at least 180 deg. of the circumference of the mandrel. The former (8) applies a circumferential tension to the strip, for a tight overlapping of successive windings ready for welding (25).