Blast furnace tap hole drill with centralizing drill rod support

摘要

A blast furnace tap hole drill is provided having an elongated feedshell which supports a percussion drill, drill rod assembly, and a centralizing drill rod support disposed between the percussion drill and a stationary forward end drill rod support, and a drive means for advancing the percussion drill and centralizing drill rod support in unison along the length of the feedshell such that the advancing motion of the centralizing drill rod support ceases as it nears the forward drill rod support without stopping the advancing motion of the percussion drill.