Explosive pipe cutting

An explosive material-energized internal method of cutting an elongated tubular cylinder into axially segregated segments, said method comprising the steps of:

• disposing a conforming metal shell-surrounded hourglass-shaped explosive material mass having a central cylindrical hourglass stem portion, two joined conical frustum hourglass reservoirs and an hourglass-surrounding airspace region within said tubular cylinder at a selected axial cutting location thereof;
• detonating said explosive material mass starting at an hourglass stem portion midpoint region to form, in said hourglass-surrounding airspace region, an initial plasticized metal slug from a portion of said conforming metal shell surrounding said hourglass;
• receiving supplemental quantities of plasticized metal from midpoint-removed parts of said conforming metal shell surrounding said hourglass stem portion, and surrounding said hourglass reservoirs, into said initial plasticized metal slug as said detonation propagates away from said hourglass stem portion midpoint into hourglass reservoirs explosive material regions;
• forming said supplemented metal slug into a thin planar sheet of increasing kinetic and thermal energy content with hourglass reservoir explosive material-sourced additional detonation energy until said hourglass reservoir detonations are completed;
• and
• impinging said thin planar sheet metal slug onto an interior surface portion and into successive wall-thickness-interior portions of said elongated tubular cylinder wall in execution of circumferential tubular cylinder cutting action and tubular cylinder segregation into axial segments as said hourglass reservoir detonations propagate to completion.

Radially acting plasticized metal slug explosive energy cutter apparatus for separating an elongated cylindrical member into axially segregated cylindrical segments, said apparatus comprising the combination of:

• an explosive material mass of overall hourglass shape disposed along a central axis of said elongated cylindrical member and having an axially disposed central cylindrical portion terminating in axially extending conical frustum portions of increasing radial diameter orthogonal of said central axis at opposed axial ends thereof;
• a conformal enclosure member disposed surrounding lateral surface portions of said explosive material mass and having a mating hourglass shape which also includes an axially disposed central cylindrical portion terminating in axially extending conical frustum portions of increasing radial diameter along said central axis of said elongated cylindrical member;
• said conformal enclosure member being comprised of a explosive detonation temperature and pressure-responsive plasticizable metal material;
• a closed-end enclosure member received within said elongated cylindrical member surrounding lateral and an end portion of said conformal enclosure material surrounded explosive material mass;
• a cutter apparatus positioning element received in said elongated cylindrical member adjacent a cutting location thereof;
• and
• an explosive material igniter fuse member centrally located within said hourglass shape central cylindrical portion of said explosive material mass.

The method for improving cutting performance of a vee shaped explosive charge energized plasticized metal cutter comprising the steps of:

• adding to an amount of explosive and plasticizable metal materials available for cutting action in said vee shaped explosive charge cutter by altering a cross sectional shape characteristic of said vee shaped explosive charge;
• said cross sectional shape characteristic altering including adding at an axial center portion of said vee shaped explosive charge, intermediate explosive detonation-plasticizable metal covered explosive charge vee-half portions, an axially extending central cylindrical explosive charge section of smaller diameter than a largest diameter of said explosive charge vee-half portions;
• said added axially extending central cylindrical explosive charge section being received in an axially extending central cylindrical enclosure of explosive detonation-plasticizable metal;
• detonating said explosive material commencing at a central point of said added axially extending central cylindrical explosive charge section said detonation propagating thence along said axially extending central cylindrical section into said explosive charge vee-half portions.