Processes of and apparatus for producing seamless annular bodies

Claim 2

APPARATUS FOR FORMING A SPLICELESS ANNULAR ARTICLE HAVING RUBBER-LIKE CHARACTERISTICS AND HAVING A SUBSTANTIALLY CYLINDRICAL INNER SURFACE FROM PLASTIC MATERIAL, COMPRISING A PAIR OF CONCENTRIC MOLD MEMBERS DEFINING BETWEEN THE INNER SURFACE OF THE OUTER MOLD MEMBER AND THE OUTER SURFACE OF THE INNER MOLD MEMBER AN ANNULAR MOLD CAVITY, SAID OUTER SURFACE OF SAID INNER MOLD MEMBER BEING SUBSTANTIALLY CYLINDRICAL, MEANS FOR EXTRUDING SAID MATERIAL INTO SAID CAVITY AND FOR ADVANCING SAID MATERIAL AXIALLY THROUGH SAID CAVITY TO FILL SAID CAVITY WHILE MAINTAINING A FIXED AXIAL RELATION BETWEEN THE INNER AND OUTER BOUNDARIES OF SAID CAVITY DURING THE ENTIRE ADVANCE OF SAID MATERIAL THROUGH SAID CAVITY, MEANS FOR AXIALLY DISPLACING ONE OF SAID MOLD MEMBERS RELATIVE TO THE OUTER OF SAID MOLD MEMBERS WITH THE ARTICLE SEATED IN SAID OUTER MOLD MEMBER TO SEPARATE SAID MOLD MEMBERS, AND MEANS FOR EFFECTING A RELATIVE ROTATION BETWEEN SAID INNER AND OUTER MOLD MEMBERS DURING THE ENTIRE ADVANCE OF SAID MATERIAL THROUGH SAID CAVITY AND DURING THE AXIAL DISPLACEMENT OF SAID ONE MOLD MEMBER RELATIVE TO SAID OTHER MOLD MEMBER, SAID EXTRUDING MEANS BEING EFFECTIVE TO EXTRUDE MATERIAL INTO ONE AXIAL EXTREMITY OF SAID CAVITY, AND SAID INNER MOLD MEMBER BEING PROVIDED WITH RELATIVELY SHALLOW HELICAL SCREW FLIGHTS IN SAID OUTER SURFACE THEREOF, SAID HELICAL SCREW FLIGHTS IN SAID OUTER SURFACE OF SAID INNER MOLD MEMBER FURTHER ADDING THE MOVEMENT OF THE FINISHED ANNULAR ARTICLE RELATIVE TO SAID INNER MOLD MEMBER UPON RELATIVE SEPARATION OF THE LATTER AND SAID OUTER MOLD MEMBER.