| 摘要 |
The invention relates to a shaft-furnace tap, especially for blast furnaces having body diameters amounting to up to 15 m. To reduce the flowing distance of the jet of liquid metal with slag issuing during the tap, the taphole is advantageously made two-stage or multi-stage according to the invention, the diameter increasing discontinuously in steps towards the outside. This results in pressure losses and particularly in reduction of the flow velocity of the issuing jet, so that the flowing distance in the tapping runner is reduced. Furthermore, the invention relates to a drilling tool in a guided positionable taphole-drilling machine for making a taphole of the type described above. This is achieved in an especially advantageous way by means of a drilling tool, in which, on the drill rod carrying a drill bit on its end face, a further drill bit is displaceable and is brought to bear non-rotatably against a driving cone at an axial distance from the drill bit located on the end face. By means of a drilling tool of this type, not only the guidance of the taphole-drilling machine can be maintained, but also the at least two-stage taphole can be produced in a single operation.
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