GB1349679A - Extrusion of hollow products - Google Patents

Abstract

1349679 Sizing extruded tubes DEMAG AG 19 April 1971 [5 March 1970] 23271/71 Heading B5A A plastics tube 19, extruded from a die head 18, is sized by contact with a part 2 of an inner mandrel and a part 1 of an outer die and then cooled by fluid admitted to spaces 7, 5, sealed downstream to the tube 19 by seals 10, 9, and respectively defined between the inner and outer surfaces of the tube 19, and outer and inner surfaces of members 6, 3 of the mandrel and die which, in the downstream direction, are of progressively increasing spacing from the tube 19. The mandrel parts 2 and 6 are axially adjustably mounted on a tube 8 secured at a flange 35 to the die head 18, and the die parts 1 and 3 are secured at a flange 36 to the die head. Cooling chambers, e.g. 37, 38, are also provided within the mandrel parts 2 and 6, and around the die parts 1 and 3. The space between the flange 35 and mandrel 2 may be supplied with supporting air for the tube 19. The outer and inner surfaces, of the parts 6, 3, may be of conical, or stepped configuration to provide the increasing spacing from the tube 19. The cooling agent is conveyed to and from the apparatus through connections 11 to 17, and is preferably fed under pressure to be sprayed into the wall of tube 19, through feed conduits distributed around the periphery. In the Fig. 1 embodiment helical ribs 4 guide the coolant through the chambers 7, 5. In the Fig. 2 embodiment (not printed), the ribs 4 are omitted, and coolant is supplied to the various chambers within the extruded tube 22 by telescopic tubes or flexible conduits which pass through the extrusion head (24).