Method of manufacturing composite projectile body embedded with preformed fragments

Patent metadata

Field	Value
Publication number	US-11041704-B1
Application number	US-201715658974-A
Country	US
Kind code	B1
Filing date	Jul 25, 2017
Priority date	Jul 25, 2017
Publication date	Jun 22, 2021
Grant date	Jun 22, 2021

Abstract

A method for preparing a composite projectile body with preformed fragments precisely embedded within the walls of the projectile body. The process utilizes a combination of additive manufacturing and advanced powder metallurgy fabrication techniques. Specifically a skeletal structure or prefabricated cage body is filled with preformed fragments. The cage structure may be situated on a mandrel or tool inside a container. The container is filled with metal powder, degassed under vacuum, and sealed. The canister is then subjected to heat and pressure to consolidate the powder to full density. The canister is then removed and the compacted billet product is further machined to obtain a desired projectile body.

First claim

What is claimed is:

1. A method for manufacturing a projectile body embedded with preformed fragments comprising:
fabricating a cage body comprising a circular ring shaped base and a plurality of ribs extending axially forward from the circular ring shaped base thereby forming the shape of a projectile body, said plurality of ribs each comprising a hollow interior volume defining a continuous longitudinal channel extending along a length of said rib for holding a plurality of spherical preformed fragments oriented in a line along the length of said rib by directly contacting the preformed fragments;
loading the cage body with the plurality of preformed fragments by placing said preformed fragments within said plurality of continuous longitudinal channels via an opening in each of the plurality of ribs;
placing the cage body around a mandrel within a canister;
filling the canister with metal casing powder, and wherein the metal casing powder completely surrounds the cage body and plurality of preformed fragments;
subjecting the canister assembly to elevated heat and pressure conditions wherein the metal casing powder and the supporting cage body are metallurgically processed into a monolithic unit; wherein the monolithic unit comprises the preformed fragments completely encapsulated in the predetermined location; and
machining the monolithic unit into a projectile shape.

2. The method of claim 1 , wherein the cage body is the same material as the metal casing powder, and the preformed fragments have a higher density and higher melting point than the cage body material.

3. The method of claim 1 , wherein the plurality preformed fragments have the same shape and size.

4. The method of claim 1 , wherein the metal cage body and the metal casing powder are composed of high strength alloy steel.

5. The method of claim 1 , wherein the cage body is prepared by a technique selected from the group consisting of additive manufacturing, lost-wax casting, spin-casting, or sheet metal forming.

6. The method of claim 1 , wherein the preformed fragment material has a higher melting point than the casing material.

7. The method of claim 1 , wherein the preformed fragment material has a higher density than the casing material.

8. The method of claim 1 , wherein the canister assembly is subject to hot isostatic pressing.

9. The method of claim 1 , wherein the supporting cage body is comprised of a metal or metal alloy selected from the group consisting of steel, aluminum, copper, magnesium, bismuth, or tin.

10. The method of claim 1 , wherein the supporting cage body is comprised of a reactive metal selected from the group consisting of zinc-zirconium composite solid metal, aluminum-magnesium-zirconium composite solid metal, or aluminum-magnesium-bismuth trioxide-iron trioxide composites solid metal.

11. The method of claim 1 , wherein the preformed fragment is comprised of tungsten, steel or reactive material.

Assignees

• Us Gov Sec Army
• Us Army

Inventors

• Ellis Michael E
• Bruno Michael V
• Kapoor Deepak
• Zahrah Tony F
• Rowland Roderick
• Lawver Steven C

Classifications

• Y02P10/25

  Process efficiency · CPC title

• F42B33/00

  Manufacture of ammunition; Dismantling of ammunition; Apparatus therefor (F42B5/188 takes precedence; manufacturing processes for hollow charges F42B1/036; manufacture of blasting cartridge initiators F42B3/195) · CPC title

• F42B12/32 Primary

  the hull or case comprising a plurality of discrete bodies, e.g. steel balls, embedded therein {or disposed around the explosive charge} · CPC title

• B22F10/00

  Additive manufacturing of workpieces or articles from metallic powder (apparatus or devices therefor B22F12/00) · CPC title

• B22F3/15

  Hot isostatic pressing · CPC title