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

Apparatus for butt-welding tubular plastic members to each other comprising:

• a mold member of insulating material having a cylindrical cavity therein of sufficient length to accommodate a pair of tubular plastic members in abutting end-to-end relationship;
• an electrode pin member of conductive metallic material mounted concentrically within and spaced from said mold member;
• an electrode ring member mounted on the outside of said mold member opposite the upper end portion of said pin member;
• and
• means for passing radio frequency energy between said electrode pin and said electrode ring member;
• said electrode pin member having a locating shoulder formed at the base thereof for properly positioning a plastic tubular member inside said mold member with one end of said plastic tubular member abutting said locating shoulder and with the other end of said plastic tubular member located inside said electrode ring member.

A method of butt-welding tubular plastic members to each other comprising the steps of:

• a. positioning a pair of tubular members of plastic material in end-to-end abutting relationship inside a cylindrical cavity formed in a mold member made of insulating material;
• b. positioning an electrode pin member formed of a metallic conductive material inside said tubular members a sufficient distance whereby the end portion of said pin member is positioned at the abutting edges of said tubular members;
• c. positioning an electrode ring member around the outside of said mold member in the area where said tubular members abut each other;
• and
• d. passing radio frequency energy between said electrode pin member and said electrode ring member to thereby heat the abutting ends of the tubular members and cause them to be welded together;
• and
• e. cooling the areas of the two plastic tubular members adjacent the abutting ends thereof during step (d) by directing a flow of cooling fluid to such abutting areas.