CUTTERS FOR SEVERING OBJECTS IN BORES

1 . A blowout preventer, comprising:

a main body having a through bore;

an insert disposed in the main body;

the insert having a first segment and a second segment defining a passage between the segments oriented transversely to the through bore;

each of the first segment and the second segment having an opening coincident with the through bore;

a cutter disposed in the passage and configured for severing objects in the through bore, the cutter comprising:

a planar body having a top surface, a bottom surface, a front end, and a back end;

the planar body having an opening passing from the top surface through the bottom surface, wherein the opening is encircled by the planar body;

a cutting edge disposed on a side of the opening proximate the back end of the planar body;

the planar body configured for placement with the opening coincident with the through bore; and

wherein the planar body is configured to receive a propelled member to contact the body to propel the planar body across the through bore for the cutting edge to sever any object in the through bore.

2 . The blowout preventer of claim 1 wherein the cutter planar body comprises holes or voids formed on the body apart from the opening.

3 . The blowout preventer of claim 1 wherein the cutter cutting edge comprises at least one protrusion extending away from the cutting edge.

4 . The blowout preventer of claim 1 further comprising a shearable pin extending from one of the top surface or the bottom surface of the cutter planar body.

5 . The blowout preventer of claim 1 wherein the cutter cutting edge comprises one of polycrystalline diamond or cubic boron nitride.

6 . The blowout preventer of claim 1 wherein the propelled member consists of a gate configured for gas propulsion into contact with the back end of the planar body to propel the planar body across the through bore.

7 . (canceled)

8 . A method for severing objects in a bore, comprising:

placing a cutter within an insert in a blowout preventer having a housing with a through bore;

the insert having a first segment and a second segment defining a passage between the segments oriented transversely to the through bore;

each of the first segment and the second segment having an opening coincident with the through bore;

the cutter placed with an opening on the cutter coincident with the through bore in the housing, the cutter including:

a planar body having a top surface, a bottom surface, a front end, and a back end;

the opening passing from the top surface through the bottom surface, wherein the opening is encircled by the planar body;

a cutting edge disposed on a side of the opening proximate the back end of the planar body;

and

propelling a member within the housing to contact the body to propel the planar body across the bore for the cutting edge to sever any object in the bore.

9 . The method of claim 8 wherein the member consists of a gate configured for travel within the housing to transfer kinetic energy to move the planar body across the through bore.

10 . (canceled)

11 . A blowout preventer, comprising:

a main body having a through bore;

an insert disposed in the main body;

the insert having a planar upper segment and a planar lower segment defining a passage between the segments oriented transversely to the through bore;

each of the upper segment and the lower segment having an opening coincident with the through bore;

each of the upper segment and the lower segment having a seal arrangement to restrict fluid flow between the through bore and the passage;

a cutter disposed in the passage, the cutter comprising:

a planar body having a top surface, a bottom surface, a front end, and a back end;

the planar body having an opening, wherein the body is configured for placement with the opening coincident with the through bore;

a cutting edge on a surface of the opening in the planar body; and

wherein the planar body is configured to move across the through bore for the cutting edge to sever any object in the through bore.

12 . The blowout preventer of claim 11 wherein the cutting edge comprises a layer disposed thereon to sealingly cover the edge.

13 . The blowout preventer of claim 11 wherein the cutting edge comprises at least one protrusion extending away from the cutting edge.

14 . The blowout preventer of claim 11 further comprising a shearable pin extending from one of the top surface or the bottom surface of the cutter planar body.

15 . The blowout preventer of claim 11 further comprising a gate configured for movement along the passage to contact the cutter planar body to propel the planar body across the through bore.

16 . The blowout preventer of claim 15 further comprising a charge disposed thereon and configured to produce a rapid gas expansion when activated.

17 . The blowout preventer of claim 16 wherein the gate is configured for propulsion via the rapid gas expansion to propel the cutter across the through bore.

18 . The blowout preventer of claim 11 wherein the seal arrangement in each of the upper segment and the lower segment comprises a seal disposed in a channel formed in the segment.

19 . The blowout preventer of claim 18 wherein each seal in each of the upper segment and the lower segment comprises a surface facing the passage.

20 . The blowout preventer of claim 18 wherein each seal in each of the upper segment and the lower segment is positioned on the segment with a central opening in the seal coincident with the through bore.