APPARATUS FOR FORMING DOUBLE-WALL THERMOPLASTIC TUBE WITH CONNECTION COUPLING Russian patent published in 2007 - IPC B29C49/78 B29C49/04 B29L23/00 

FIELD: apparatus for making double-wall thermoplastic tube with connection coupling.

SUBSTANCE: at making tube by means of apparatus according to invention approximately annular space is formed in it at extrusion through extrusion head of first elastic tube to molding tunnel and of coaxial second elastic tube. Second elastic tube is made by means of second die set arranged downstream in direction of motion of casting molds in molding tunnel for extruding second elastic tube to first elastic tube. Molding tunnel is formed at least by successive row of casting molds placed along path of molding tunnel and it has at least in first portion ribbed molding wall and at least in second portion groove corresponding to connection coupling. Apparatus also includes first gaseous duct arranged between two die sets and second gas duct passing downstream from second die set in motion direction of casting molds in molding tunnel. Apparatus also includes unit for controlling compressed gas flow rate communicated with first gas duct for creating pressure value p1 or p2 in space between two elastic tubes by means of compressed gas from outlet of first gas duct. Unit for controlling compressed gas includes pressure regulator and it is communicated with second gas duct for creating pressure p3 higher than atmospheric pressure at inner side of second elastic tube by means of compressed gas discharging from second gas duct. Control unit is used for said apparatus for controlling compressed gas flow rate. Pressure regulator is connected with first gas duct through compressed gas line communicating with additional compressed-gas tank for gas exchange. Invention is realized at connecting said space with compressed-gas tank in such a way that to smooth pressure changes in said space by means of vessel for compressed gas. Invention provides elimination of curvature of inner tube in first portion of molding tunnel at cooling elastic tubes and it provides desired expansion of first elastic tube for forming connection coupling.

EFFECT: improved design of apparatus.

14 cl, 4 dwg