Casing cutter

Claim 1

IN A CASING CUTTER FOR SUSPENSION IN A WELL BORE: A SHOOTING MANDREL; A TUBULAR THIN-WALLED SHELL; A PAIR OF MIRROR-IMAGE HOUSINGS CONSTRUCTED OF FRANGIBLE MATERIAL; CIRCULAR SHAPED-CHARGE EXPLOSIVE PORTIONS AND LINER MEANS EXTENDING AROUND THE PERIPHERY OF SAID SHAPED CHARGE PORTIONS ATTACHED TO SAID HOUSING, SAID HOUSINGS BEING SHAPED FOR RECEPTION IN THE OPEN ENDS OF SAID CYLINDRICAL SHELL WITH SAID SHAPED CHARGE PORTIONS ABUTTING TO FORM ANNULAR SHAPED CHARGE MEANS; A PAIR OF IDENTICAL DOMED HEADS CONSTRUTED OF FRANGIBLE MATERIAL, EACH OF SAID HEADS HAVING AN OUTER CONVEX WALL AND AN INNER CONCAVE WALL, A PERIPHERAL WALL PORTION SHAPED FOR RECEPTION WITHIN SAID SHELL AND COUPLING MEANS ON THE CONVEX WALLS; SAID HEADS HAVING PERIPHERAL FLANGE PORTIONS EXTENDING THEREFROM AND DEFINING THE UPPER LIMIT OF SAID PERIPHERAL WALL PORTIONS; SEAL MEANS AROUND EACH OF SAID PERIPHERAL WALL PORTIONS; SAID HEADS AND HOUSINGS HAVING BORE MEANS ALIGNED FOR RECEIVING A DETONATING CORD WHEN SAID HEADS ARE FITTED INTO THE ENDS OF SAID SHELL WITH THE CONVEX WALLS OF SAID HEADS FACING AWAY FROM EACH OTHER; AND CLOSURE MEANS COUPLED TO THE COUPLING MEANS OF ONE OF SAID HEADS FOR CLOSING ONE END OF SAID BORE MEANS THEREBY LEAVING THE OTHER OF SAID COUPLING MEANS ON THE OTHER OF SAID HEADS FOR COUPLING TO SAID SHOOTING MANDREL.