Thermoplastic tube

Abstract

A method for producing a tube section from thermoplastic material, in which a tube section is extruded by means of an extruder which is provided with an extruder die having an inner core, which inner core defines an axial hollow space in the tube section, the tube section coming out of the extruder die downstream of the extruder die being internally cooled by means of an internal cooling member and externally cooled by means of an external cooling device. Immediately after the tube section leaves the extruder die, the internal cooling member brings about internal cooling of the tube. The external cooling device is positioned downstream of the internal cooling member, so that the external cooling of the tube section is brought about after the internal cooling.

1 - 14 . (canceled)  
   
   
       15 . A method for producing a socketed biaxially oriented thermoplastic tube starting from a prefabricated tube of biaxially oriented thermoplastic material having a tube body and an integral end part at least one end of said tube body, said end part having a greater wall thickness than the tube body, the axial stretching of the end part being at least equal to the axial stretching of the tube body, the method comprising the step of subject an end part of said prefabricated tube to a socket-forming operation.  
   
   
       16 . A method according to  claim 15 , in which an end part of the prefabricated tube has a plurality of annular areas which adjoin one another and have a wall thickness which varies from annular area to adjoining annular area, the wall thickness of a plurality of the annular areas being greater than the wall thickness of the tube body.  
   
   
       17 . A method according to  claim 15 , in which an end part of the prefabricated tube has a plurality of annular areas which adjoin one another and have a wall thickness which varies from annular area to adjoining annular area, the wall thickness of a plurality of the annular areas being greater than the wall thickness of the tube body, and in which an annular area of said end part having a larger wall thickness than the tube body is deformed, during said socket-forming operation, into an outwardly bulging groove wall, which delimits an internal groove in the socketed tube for the accommodation of a sealing ring.  
   
   
       18 . A method according to  claim 15 , in which an end part of the prefabricated tube has a plurality of annular areas which adjoin one another and have a wall thickness which varies from annular area to adjoining annular area, the wall thickness of a plurality of the annular areas being greater than the wall thickness of the tube body, and in which an annular area of said end part with a larger wall thickness projects inwardly with respect to the internal diameter of the tube body following the socket-forming operation.  
   
   
       19 . A biaxially oriented thermoplastic tube, which tube has a tube body and, at one or both ends, an integrally formed socket, said tube having an axial stretching of the plastics material in the socket which is substantially equal to the axial stretching of the thermoplastic material in the tube body.  
   
   
       20 . A biaxially oriented thermoplastic tube, which tube has a tube body and, at one or both ends thereof, an integrally formed socket, the socket having an outwardly bulging groove wall which delimits an internal groove in the tube for the accommodation of a sealing ring, wherein the groove wall has a wall thickness which is greater than or equal to adjacent parts of the socket which have a smaller diameter.  
   
   
       21 . A biaxially oriented thermoplastic tube, which tube has a tube body and, at one end, an integrally formed socket and, at the other end, a spigot designed to fit into a socket of a similar tube, wherein the spigot has a greater wall thickness than the tube body.  
   
   
       22 - 29 . (canceled)