Method and apparatus for butt-welding tubular plastic members to each

Abstract

The apparatus is comprised of three basic parts, a mold member, an electrode pin member mounted inside the mold member and an electrode ring member mounted on the outside of the mold member. The mold member is made of an insulating, non-metallic material and is provided with a central cavity in which the pin member is mounted. The electrode pin member is made of a conductive metallic material and is provided with a cooling passageway system in the interior thereof. A pair of tubular members of plastic material are inserted into the open end of the mold cavity with their ends abutting each other in an area opposite the end portion of the pin member, with the electrode ring member positioned in the same general area. Radio frequency energy is transmitted between the electrode pin member and the electrode ring member and simultaneously therewith air under pressure is introduced into the passageway system inside the pin. The radio frequency energy will generate heat in the material of the plastic tube at the abutting ends thereof, causing the tubes to be welded together. The air flowing in the passageway inside the pin is directed to the areas of the two tubes adjacent the abutting ends thereof to thereby localize the heat produced in the desired area, namely where the ends of the tube abut each other.