Apparatus for forming precision glass tubing from a molten glass supply

Claim 1

APPARATUS FOR FORMING HIGH-PRESISION TUBING FROM MATERIAL WHICH IS HARD AT NORMAL ATMOSPHERIC TEMPERATURES AND WHICH IS RENDERED FLOWABLE AND WORKABLE UPON HEATING AND FOR CONTROLLING THE BORE OF SAID TUBING WITHIN VERY CLOSE TOLERANCES, WHICH COMPRISES: A CUP FOR HOLDING SAID MATERIAL FORMED WITH A CENTAL OPENING IN THE BOTTOM THEREOF; HEATING MEANS AT SAID CUP FOR HEATING THE MATERIAL THEREIN TO FLOWABLE AND WORKABLE CONDITION; FORMING MEANS INCLUDING A SMOOTH TAPERED SURFACE SURROUNDING THE OPENING IN THE CUP AND A CONICAL, TUBULAR MEMBER DISPOSED IN THE OPENING AND PROJECTING OUTWARDLY THEREFROM AND HAVING A SMOOTH EXTERIOR SURFACE FOR FORMING THE HEATED MATERIAL INTO A TUBE AS IT FLOWS THROUGH THE OPENING; A CONTROL MEMBER EXTENDING OUTWARDLY FROM AND BEYOND SAID CONICAL MEMBER AND SPACED CONCENTRICALLY INWARDLY THEREFROM FOR USE IN CONTROLLING THE BORE OF THE TUBE TO UNIFORM DIAMETER; TUBE DRAWING MEANS SPACED OUTWARDLY FROM SAID CONTROL MEMBER FOR DRAWING THE TUBE THUS FORMED OUTWARDLY THROUGH SAID OPENING AND OVER SAID CONICAL MEMBER AND CONTROL MEMBER TO REDUCE ITS DIAMETER AND WHILE IT IS SUBJECTED TO COOLING ACTION TO AN AREA WHERE THE TUBE HAS COOLED SUFFICIENTLY TO MAINTAIN ITS PHYSICAL CONFIGURATION; AND MEANS FOR CONTROLLING MINOR VARIATIONS IN THE DIMENSIONS OF THE TUBING, INCLUDING MEANS FOR SUPPLYING GAS UNDER PRESSURE AT A METERED RATE OF FLOW THROUGH THE CONCIAL TUBULAR MEMBER TO THE ANNULAR ZONE SURROUNDING THE CONTROL MEMBER AND FOR WITHDRAWING SAID GAS THROUGH THE CONTROL MEMBER TO THEREBY PROVIDE AN AIR BEARING FOR SAID TUBING BETWEEN THE END PORTION OF THE CONTROL MEMBER AND THE TUBING.