BORRNINGSANORDNING FOER FRAMSTAELLNING AV BORRHAOL MED BAKSKAERNING.

摘要

In order to obtain a pivot bearing through the drill shank (1) itself for the pivoting movements performed during the drilling operation, this drill shank (1) has an arched portion (5) which narrows towards the ends of the drill shank (1). In order to prevent excessive wear in the area of the arched portion (5), a bearing ring (10) is attached there which is easily interchangeable as a wearing part. ……