Extruding head for making reticulated seamless tubes

摘要

A relative nutational movement is provided between a member carrying teeth or other radial projections and a member against which these projections bear, these two members being just downstream of an annular extrusion gap that produces a plastic tube which is slit by the teeth or other projections passing through the tube wall in succession and bearing against the backing member. As it comes out from the slitting or punching produced by these members, the tubular material is stretched to and over a mandrel and cooled there to produce a tubular netting or a perforated sheath. Either the toothed member or the backing member may be fixed while the other is moved in a movement of nutation and the toothed member may have externally or internally directed teeth.