Device for manufacturing a double-walled, thermoplastic tube with a connecting sleeve

A device comprising:

• a mould tunnel that comprises at least one row of moulds guided on a path, has a corrugated mould wall in at least one first section and a sleeve recess corresponding to the connecting sleeve in at least one second section,
• an extruder equipped with an extrusion head, where the extrusion head has a first die for extruding a first tube into the mould tunnel and a second die located downstream in the direction of motion of the moulds in the mould tunnel for extruding a second tube,
• a first gas duct located between the first and second dies and a second gas duct opening downstream of the second die in the direction of motion of the moulds of the mould tunnel,
• a first compressed gas controller connected to the first gas duct, the first compressed gas controller having at least two pressure settings where a first pressure setting is for a first pressure above atmospheric pressure and a second pressure setting is for a second pressure less than the first pressure and above atmospheric pressure, the pressure settings control the pressure of the compressed gas flowing out of the mouth of the first gas duct in the space between the two tubes,
• a second compressed gas controller connected to the second gas duct, the second compressed gas controller having at least one pressure setting for a third pressure above atmospheric pressure on the inside of the second tube with the compressed gas flowing out of the mouth of the second gas duct, and
• a controller connected to the first and second compressed gas controllers, said controller controls the pressure settings used by the first and second compressed gas controllers.

A device for use with a molding tunnel having molds to form double-walled thermoplastic pipe with a connecting sleeve, said device comprising:

• an extrusion head having a first die for extruding a first flexible tube into said molding tunnel, and a second die that is arranged downstream in direction of movement of said molds within said molding tunnel for extruding a second flexible tube,
• a first gas duct arranged between said two dies,
• a second gas duct that opens out downstream of said second die in the direction of movement of the molds of the molding tunnel,
• a first compressed gas controller connected to said first gas duct, said first compressed gas controller having at least two pressure settings where a first pressure setting is for a first pressure above atmospheric pressure and a second pressure setting is for a second pressure less than the first pressure and above atmospheric pressure, the pressure settings control the pressure of the compressed gas flowing out of the mouth of said first gas duct in the space between the two tubes,
• a second compressed gas controller connected to said second gas duct, and
• a controller connected to the first and second compressed gas controllers, said controller controls the pressure settings used by the first and second compressed gas controllers based on order of molds in the molding tunnel.