| 摘要 |
A device for avoiding flow disturbances and stagnation during the production of hollow or solid multilayer elongate structures. The device for the coextrusion of thermoplastics comprises an elongate central core and an external structure surrounding the central core and defining, with the latter, a central extrusion channel which runs in the direction of the longitudinal axis of the device towards an outlet orifice, in which device the external structure consists of at least one element, each element comprising a toroid feed chamber surrounding the central extrusion channel and connected to a feed source of molten thermoplastic, with an extrusion passage having an external wall and connecting the periphery of the toroid feed chamber to the central extrusion channel, and with an adjustment ring, movable transversely relative to the longitudinal axis of the device, to provide control of the flux of molten thermoplastic flowing from the toroid feed chamber to the central extrusion channel, characterized in that each adjustment ring delimits in combination a portion of the toroid feed chamber in its part which is connected to the extrusion passage and a portion of the external wall of the extrusion passage in its part which is connected to the toroid feed chamber, the other portion of the external wall of the extrusion passage connected to the central extrusion channel being delimited by an internal face of a mandrel which surrounds the central extrusion channel and against which mandrel the adjustment ring can move transversely.
|
