| 摘要 |
PURPOSE: A bit having diameter adjusting function is provided to reduce working load of workers and reduce cost required for using the bit by arbitrarily controlling opening size of the tap hole using a bit whose diameter is expanded or contracted when opening tapping hole of blast furnace. CONSTITUTION: In a bit(30) used in opening a tap hole for discharging melt in blast furnace, the bit having diameter adjusting function comprises one or more cutout elements(31a,31b,31c) on inner surface and outer surface of which screw threads(32,33) are respectively formed; an inserting member(35) which is engaged with the screw thread(32) on an inner surface of the cutout elements(31a,31b,31c), on an outer diameter of which screw thread(35a) is formed in a taper shape, and in a center of which coupling hole(35b) is longitudinally formed; and a clamping member(38) which is engaged with the screw thread(33) on an outer surface of the cutout elements(31a,31b,31c), and on an inner diameter of which screw thread(38a) is formed in a taper shape.
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