Trepanning drill bit assembly - has passage to flushing seat from end face between cutters through shank

摘要

The trepanning drill bit has a shank fitting in a chuck. The drill assembly includes a flushing head seat between the ends, connected by a transverse drilling to a lengthwise one from the cutting end, which comprises a cylindrical portion with a ring of cutters. A centering drill bit fits interchangeably in the shank end. There are one or more passages (17) which lead from a point in the end face (10) between adjacent cutters (11) inside the cylindrical wall (9), and they are connected to the drilling inside the shank (33).