Method of sealing concentric tube ends to make sealed dual-wall tube

Abstract

A method for sealing together the ends of concentrically arranged tubes of plastic material to make a double-walled tube which comprises inserting the assembled ends into a mold means conforming substantially in size to the outer periphery of the finished tube and applying heat to seal the tube ends together. Preferably, the tubes during heating are arranged concentrically with the end of one tube extending beyond the end of the other tube and if the materials of the two tubes have different melting points, the tube having the lower melting point extends slightly beyond the other tube. Preferably, a rod of material having good heat conductivity and a melting point higher than that of the plastic tubes is positioned inside the inner tube with its end slightly below the sealing area. The tube edges can be sealed together leaving an opening in the finished end or the finished end sealed completely over. The tube edges can be sealed together around a removable metal element, such as a trochar with a sharp point which is used for inserting the finished product in a body drainage area followed by removal of the trochar after locking the double-walled tube in the drainage area. The heating is preferably performed by applying high frequency radiation to the mold in which the assembled ends to be sealed are inserted followed immediately after heating with coolant circulation through the mold to quickly cool the finished product.

Dependencies are inferred from the claim text.