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A heating apparatus for drawing a glass rod having a tapered portion coupled, at its upper end, with a feed bar of an outside diameter smaller than that of the glass rod, including an apparatus housing into which the glass rod is inserted, a first sealing cover which is formed with a bore having suc

A heating apparatus for drawing a glass rod having a tapered portion coupled, at its upper end, with a feed bar of an outside diameter smaller than that of the glass rod, including an apparatus housing into which the glass rod is inserted, a first sealing cover which is formed with a bore having such a dimension as to seal a clearance between the glass rod and the bore and is hermetically mounted on an inlet opening of the apparatus housing and a second sealing cover which is movably attached to the feed bar and is formed with an aperture having such a dimension as to seal a clearance between the feed bar and the aperture. The second sealing cover has a hollow portion which is formed with a space for accommodating the tapered portion and is hermetically placed, at its lower end, on the inlet opening.

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A heating apparatus for drawing a glass rod, comprising: an apparatus housing having an inlet opening, into which said glass rod is axially downwardly inserted from said inlet opening; said glass rod having a tapered portion formed at its upper end portion such that a diameter of said tapered portio

A heating apparatus for drawing a glass rod, comprising: an apparatus housing having an inlet opening, into which said glass rod is axially downwardly inserted from said inlet opening; said glass rod having a tapered portion formed at its upper end portion such that a diameter of said tapered portion decreases in an upward direction of said glass rod; said tapered portion being coupled, at its upper end, with a feed bar for feeding said glass rod into said apparatus housing; said glass rod having an outside diameter larger than that of said feed bar; a first sealing cover which is formed with a bore having such a dimension as to seal a clearance between an outer periphery of said glass rod and said bore and is hermetically mounted on said inlet opening; and a second sealing cover which is movably attached to said feed bar and is formed with an aperture having such a dimension as to seal a clearance between an outer periphery of said feed bar and said aperture; said second sealing cover having a hollow portion; said hollow portion being formed with a space for accommodating said tapered portion of said glass rod and being hermetically placed, at its lower end, on said first sealing cover.