Cutting tool for cutting well casing

In a cutting tool mounted for rotation within a well for cutting casing therein and having a cutter body with a slot therein receiving a longitudinally extending cutter arm means mounting an upper end of said arm for pivotal movement to move the lower end of the arm radially outwardly to an expanded position for engaging the casing;

• an improved cutting blade mounted on the lower end of said arm and extending in a generally radial direction therefrom, said blade including a base having a leading planar surface inclined rearwardly from its upper end with respect to the rotation axis of said cutting tool during the cutting operation;
• and
• a plurality of inserts of a predetermined generally similar size and shape mounted on the leading planar surface of said base in a predetermined pattern and forming a leading planar cutting surface for said blade, said inserts being positioned in closely fitting relation to each other on said base in a plurality of adjacent longitudinally and transversely extending rows and progressively wearing away during the cutting operation, each of said inserts including, prior to wear, a generally arcuate lower cutting edge having a lowermost intermediate portion and adjacent opposed side portions inclined upwardly from said intermediate portion to continually present a relatively sharp cutting surface to the casing;
• said leading planar cutting surface being in a plane inclined rearwardly from the upper end of the blade an amount between around one (1) degree and twenty (20) degrees with respect to the axis of rotation of said cutting tool.

In a cutting tool mounted for rotation within a well for cutting casing therein and having a cutter body with a slot therein receiving an elongate cutter arm mounted for pivotal movement between a retracted position for being lowered within the well and an expanded radial position outwardly of the cutter body for engaging the surrounding casing;

• an improved cutting blade mounted on the lower end of said arm having a leading planar surface and a rear trailing planar surface in parallel relation to said leading planar surface, said leading and trailing planar surfaces being parallel to a plane inclined rearwardly from their upper ends an amount between around one degree and ten degrees with respect to the rotational axis of said tool;
• and
• a plurality of hard carbide inserts of a predetermined generally similar size and shape on said leading planar surface in a predetermined pattern and forming a leading planar cutting surface thereon, said leading planar cutting surface defining a lower cutting edge comprised of said inserts, each said insert having, prior to wear, a generally arcuate lowermost intermediate portion and adjacent opposed side portions inclined upwardly from said intermediate portion to continually present a relatively sharp cutting surface to the casing during the cutting operation;
• said inserts being positioned in closely fitting relation to each other on said blade in a plurality of generally longitudinally extending and transversely extending rows and having their outer exposed surfaces progressively worn away during the cutting operation, the carbide inserts in adjacent transversely extending rows being staggered transversely to provide different concentric cutting paths for the cutting elements in adjacent transverse rows.

In a cutting tool mounted for rotation within a well for cutting casing therein and having a cutter body with a slot therein receiving an elongate cutter arm mounted for pivotal movement between a retracted position for being lowered within the well and an expanded radial position outwardly of the cutter body for engaging the surrounding casing;

• an improved cutting blade mounted on the lower end of said arm and having generally planar leading and trailing faces with respect to the direction of rotation of the cutting tool, said leading and trailing faces having inner and outer sides radially spaced from each other and on opposite radial sides of said arm;
• a plurality of cutting elements on said blade adjacent the outer side of said leading face and adjacent the inner side of said trailing face;
• and
• means mount said blade on the lower end of said arm for reversal of the leading and trailing faces so that upon wear of said blade from the outer side thereof said blade may be removed and turned one hundred eighty degrees (180.degree.) for reversal of the trailing and leading faces thereof.

An improved elongate cutter arm assembly for a cutting tool adapted to be connected to a well string for being lowered within a well casing for cutting the casing, said cutter arm assembly comprising:

• an elongate cutter arm having an upper end portion adapted to be mounted on the cutting tool for pivotal radial movement between a retracted inoperable position for being lowered within the casing and a radially expanded cutting position;
• mounting means adjacent the lower end of said cutter arm;
• a cutting blade having an upper end secured by said mounting means to the lower end of said arm, said cutting blade having generally planar leading and trailing faces with respect to the direction of rotation of the cutting tool, said leading and trailing faces having inner and outer sides radially spaced from each other;
• and
• a plurality of cutting elements on said blade adjacent the outer side of said leading face and adjacent the inner side of said trailing face;
• said mounting means for mounting said blade on said arm being removable so that upon wear of said blade from the outer side thereof said blade may be removed and turned 180.degree. for reversal of the trailing and leading faces thereof.

A cutting tool mounted for rotation within a well for cutting a casing therein during rotation and comprising:

• a tubular cutter body having a longitudinally extending slot therein and adapted to be connected to a well string for being lowered within a well and being surrounded by casing to be cut;
• an elongate cutter arm received within said slot having an upper end portion and a lower end;
• means on the cutter body mounting the upper end portion of said cutter arm in said slot for pivotal movement to permit the outward swinging movement of the lower end of said cutting arm into cutting contact with the inner periphery of the adjacent casing to be cut;
• means associated with said cutting tool and selectively actuated at a predetermined well depth to engage a radially inward rear surface of said arm at a location below said mounting means to cam the lower end of the arm outwardly for engaging the casing in a cutting operation;
• a cutting blade mounted on the lower end of said arm and extending radially outwardly from said arm for first cutting a casing in a generally horizontal direction along its inner periphery and then milling away a predetermined section of the casing progressively from the upper annular edge of the casing after it has been cut horizontally, said blade having a leading planar surface with respect to the direction of rotation of said tool;
• a plurality of inserts of a predetermined generally similar size mounted on the leading planar surface of the blade in a predetermined pattern with each insert having a leading planar cutting surface, said leading planar cutting surface defining a lower cutting edge comprised of said inserts, each said insert having, prior to wear, a generally arcuate lowermost intermediate portion and adjacent opposed side portions inclined upwardly from said intermediate portion to continually present a relatively sharp cutting surface to the casing during the cutting operation, said inserts being positioned in closely fitting relation to each other in a plurality of transversely extending rows and progressively worn away from their outer exposed surfaces during the cutting operation, said planar cutting surface for each insert being in a plane inclined rearwardly from the upper end of the blade at an angle between around one (1) degree and twenty (20) degrees with respect to the rotational axis of said cutting tool during the cutting operation, the inserts in adjacent transversely extending rows being staggered transversely to provide offset concentric cutting paths for the inserts in adjacent rows.

A cutting tool mounted for rotation within a well for cutting a casing therein during rotation and comprising:

• a tubular cutter body having a longitudinally extending slot therein;
• a mandrel extending within said tubular cutter body and having a cam surface adjacent its lower end;
• fluid operating means mounting said tubular cutter body for longitudinal movement relative to said mandrel;
• an elongate cutter arm received within said slot and having an inner cam surface thereon;
• means on the cutter body mounting the upper end portion of said cutter arm in said slot for pivotal movement to permit the outward swinging movement of the lower end of said cutting arm into cutting contact with the inner periphery of the adjacent casing to be cut upon an upward longitudinal movement of said cutter body relative to said mandrel;
• said fluid operating means upon the reaching of a predetermined circulating fluid pressure in said mandrel being actuated to move said cutter body upwardly relative to said mandrel with said cam surface on said mandrel contacting said cam surface on said arm and camming the lower end of the arm outwardly for the cutting operation;
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• a cutting blade mounted on the lower end of said arm and extending radially outwardly from said arm for first cutting a casing in a generally horizontal direction along its inner periphery and then milling away a predetermined section of the casing progressively from the upper annular edge of the casing after it has been cut horizontally, said blade having a leading planar surface with respect to the direction of rotation of said tool, a plurality of accuate inserts of a predetermined generally similar size and shape mounted on the leading planar surface of the blade to form a planar cutting surface, said inserts being positioned in closely fitting relation to each other and progressively worn away from their outer exposed surfaces during the cutting operation, said planar cutting surface being in a plane inclined rearwardly from the upper end of the blade at an angle between around one (1) degree and twenty (20) degrees with respect to the rotational axis of said cutting tool during the cutting operation.