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

Claim 12:
13. A method of making a drilling unit for drilling a hole, the method comprising:
preparing a ring billet;
forming segment impact shoulders and segment reamer shoulders;
cutting the formed ring billet to smaller pieces for forming ring bit segments; and
incorporating the formed ring bit segments into the drilling unit, wherein the drilling unit comprises a drilling head, said drilling head 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
the formed 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 the segment impact shoulders and the segment reamer shoulders, 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.