Patent ID: 11959337
Assignee: MINCON NORDIC OY
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 0:
1. A drilling unit for drilling a hole, the drilling unit comprising a drilling head, said drilling head further comprising:
pulling means for pulling a casing into the hole;
a pilot bit for drilling a center hole;
connecting means; and
a ring bit assembly for reaming the center hole for the casing;
wherein said ring bit assembly is connected to said pilot bit by the connecting means and to said casing by the pulling means,
wherein said ring bit assembly comprises:
a carrier comprising carrier coupling means; and
a plurality of ring bit segments movably attached to said carrier coupling means, the pilot bit being connected to the ring bit assembly by the ring bit segments,

wherein the carrier coupling means comprise a plurality of carrier holes and carrier ribs, and the ring bit segments comprise a segment impact shoulder and a segment reamer shoulder,
wherein said segment impact shoulders are attached into the carrier holes, and
wherein said segment reamer shoulders and the segment impact shoulders are arranged to attach the ring bit segments to said carrier ribs from the inside of the carrier when said ring bit segments are in the extended position.