TH21118B - A continuous manufacturing method for double-walled pipes, with pipe sockets and equipment to implement this method. - Google Patents

Abstract

DC60 Continuous production of double-walled tubes with tube sockets (41) consisting of a smooth inner tube and an outer tube which are welded together and given transverse grooves, two ejection presses which eject the outer tube (37) and the inner tube (39) through a cross-head (8). Switches (50, 51, 56, 57) are provided to produce tube sockets (41) in a way that the speed of the ejection presses is modified in such a way that the mass flow of the molten plastic material for the production of the outer tube (37) is reduced during the production of tube sockets (41) and/or the mass flow for the production of the inner tube (39) is increased. Continuous production of double-walled tubes with tube sockets (41) consisting of a smooth inner tube and an outer tube which are welded together and given transverse grooves, two ejection presses The outer tube (37) and inner tube (39) are extruded through a common crosshead (8). Switches (50, 51, 56, 57) are arranged to produce the tube socket (41) by a means in which the extrusion speed is modified in such a way that the mass flow of the molten plastic material for the outer tube (37) is reduced during the production of the tube socket (41) and/or the mass flow for the production of the inner tube (39) is increased.

Claims (14)

1. A continuous fabrication method for producing double-walled tubes (10) with a tube socket (41) and consisting of a smooth inner tube (39') and an outer tube (37') welded to the inner tube (39') and with transverse grooves (38) which consists of the following steps: First stream extrusion of the mass of molten plastic material per unit time and forming the outer tube (37) with inner and outer sides; arranging the outer tube (37) with the corrugations of the transverse grooves (38) and corrugated channels (40) using an inner-to-outer overpressure; Second stream extrusion of the mass of molten plastic material per unit time and forming the inner tube (39) into the outer tube (37); Compressing the inner tube (39) into the corrugated channels (40) of the outer tube (37) to weld the inner tube (39) to the outer tube (37); Expanding the outer tube (37) to a specified range and using an inner-to-outer overpressure to create an approximate cylindrical tube socket with double walls. The smoothing (41) and transition section between the corrugated channel (40) and the pipe socket (41); the expansion of the inner pipe (39) during the expansion of the outer pipe (37) and the compression of the outer portion of the inner pipe (39) into the socket (41); the maintenance of the first and second mass flows in the molten plastic material per unit time constant during the arrangement of the outer pipe (37) with the transverse grooves (38) and the corrugated channel (40); and the adjustment of either the first or second mass flow in the molten plastic material per unit time to be independent of the first or second mass flow in the molten plastic material per unit time of the other during the fabrication of the pipe socket (41) and the transition section. 2. Method according to claim 1 where the mass flow of the external pipe forming (37) is reduced during the pipe forming process (41). 3. Method according to claim 1 where the second mass flow for forming the inner pipe (39) is increased during the forming of the pipe socket (41). 4. The method under claim 1, whereby the excess pressure acting from the inside to the outside is created, at least partially, by using a partial vacuum fed from the outside. 5. The method under claim 1 in which a super-atmospheric gas is blown into the space between the outer tube (37) and the inner tube (39) after the inner tube (39) is extruded into the outer tube (37) and before the inner tube (39) is pressed into the corrugated channel (40) of the outer tube (37). 6. The method according to claim 1, where the empty space (58) between the outer pipe (37) and the inner pipe (39) is vented, while the outer pipe (37) and the inner pipe (39) are expanded to create a pipe socket (41). 7. The method according to claim 1, where the inner tube (39), when expanded for use in constructing the tube socket (41), is internally actuated by a gas at pressures above atmospheric pressure and the full surface of the inner tube (39) is literally compressed against the outer tube (37). 8. A continuous production method for producing double-walled tubes (10) with tube sockets (41) and consisting of a smooth inner tube (39') and an outer tube (37') welded to the inner tube (39') and with transverse grooves (38), which consists of the following steps: the provision of a heat-recirculating half-shell (12,12') to form a mold piloted in the conveying direction (4); the extrusion of the first stream of molten plastic mass per unit time into the mold and the forming of the outer tube (37) with inner and outer sides; the provision of the outer tube (37) with transverse grooves (38) and corrugated channels (40) using an overpressure applied from the inside to the outside; the extrusion of the second stream of molten plastic mass per unit time into the mold. and the forming of the inner tube (39), the compression of the inner tube (39) into the corrugated channel (40) of the outer tube (37) to create a fused inner tube (39) to the outer tube (37), the expansion of the outer tube (37) to a specified range and by applying an overpressure acting from the inside to the outside to create an approximate cylindrical tube socket with a truly smooth wall (41), and the transition between the corrugated channel (40) and the tube socket (41), and the expansion of the inner tube (39) during the expansion of the outer tube (37) and the compression of the outer portion of the inner tube (39) into the socket (41), maintaining the first and second mass flows in the molten plastic material per unit time constant during the arrangement of the outer tube (37) with the transverse grooves (38) and the corrugated channel (40), and adjusting either the first or second mass flow in the molten plastic material per unit time independent of the first or second flow. The second mass in the molten plastic material per unit time is another line during the pipe socket fabrication (41) and transition section. 9. Method according to claim 8 where the first flow current of the mass for forming the outer pipe (37) is reduced during the forming of the pipe socket (41). 10. Method according to claim 8 where the second mass flow for forming the inner pipe (39) is increased during the forming of the pipe socket (41). 11. The method under claim 8, whereby the excess pressure acting from the inside to the outside is created at least partially by using a partial vacuum fed from the outside. 12. The method under claim 8, whereby a super-atmospheric gas is blown into the space between the outer tube (37) and the inner tube (39) after the inner tube (39) is extruded into the outer tube (37) and before the inner tube (39) is pressed into the corrugated channel (40) of the outer tube (37). 13. The method according to claim 8, where the empty space (58) between the outer pipe (37) and the inner pipe (39) is vented, while the outer pipe (37) and the inner pipe (39) are expanded to create a pipe socket (41). 14. The method according to claim 8, where the inner tube (39), when expanded for use in constructing the tube socket (41), is internally actuated by a gas at a pressure above atmospheric pressure and the full surface of the inner tube (39) is literally compressed against the outer tube (37).