Abstract A method and apparatus for producing tubing having different characteristics, e.g. physical, chemical and the like, along its axial length including two or more extruders that feed different plastic materials to a mixing and extruding die with a sequencing control for decreasing or interrupting the flow from one extruder and simultaneously increasing the flow from one other extruder and after a predetermined time interval reversing this operation to produce a tube having repeating different characteristics which tube may thereafter be cut into sections including portions containing each characteristic. In one embodiment a composite extrusion is employed with a control for increasing the flow of one plastic to one of the dies and for simultaneously and proportionally decreasing the flow to the other of the dies to produce a tube having gradually changing physical properties along its axial length while maintaining a uniform cross-section tube.
An apparatus for the manufacture of tubing having different characteristicS along its length, comprising: a first plastic extruder device for preparing a first plastic having a predetermined characteristic, a second plastic extruder device for preparing a second plastic having a characteristic different from said first plastic, extruding die means for receiving plastic from both of said extruding devices, and control means for increasing the volume flow from one extruder device and for decreasing the volume flow from the other extruder device to vary the characteristics of the resulting tubing along its length, said control means including valve means between the extruder device and the die means, said valve means controlling the volume flow from each of said extruder devices to said die means, said valve means including a first valve between said first extruder device and said die means and a second valve between said second extruder device and said die means, said valve means each having an outlet connectable to scrap collection means to achieve total scrap reclamation, said control means proportionally controlling said first and second valves.
Claim 2
Independent Claim
179 words
An apparatus for the manufacture of tubing having different characteristicS along its length, comprising: a first plastic extruder device for preparing a first plastic having a predetermined characteristic, a second plastic extruder device for preparing a second plastic having a characteristic different from said first plastic, extruding die means for receiving plastic from both of said extruding devices, and control means for increasing the volume flow from one extruder device and for decreasing the volume flow from the other extruder device to vary the characteristics of the resulting tubing along its length, said control means including valve means between the extruder device and the die means, said valve means controlling the volume flow from each of said extruder devices to said die means, said valve means including a first valve between said first extruder device and said die means and a second valve between said second extruder device and said die means, said valve means each having an outlet connectable to scrap collection means to achieve total scrap reclamation, said control means proportionally controlling said first and second valves.