Drill bit tube for providing circular drilling in building, has sound-absorbing layer arranged in annular space between inner arranged protective tube and tube mantle of drill bit tube, where protective tube is provided with cover

摘要

The drill bit tube (10) has an inner arranged protective tube (21) and a sound-absorbing layer (22) formed from a synthetic resin, where the sound-absorbing layer is arranged in a annular space (23) between the inner arranged protective tube and a tube mantle (24) of the drill bit tube. The inner arranged protective tube is provided with a cover (20). The sound-absorbing layer slides during drilling the free-section.