Press load process for warheads

Patent metadata

Field	Value
Publication number	US-11209255-B1
Application number	US-202017010933-A
Country	US
Kind code	B1
Filing date	Sep 3, 2020
Priority date	Sep 10, 2019
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

An improved process provides high-density pre-form billets that meet dimensional limitations required for case-load tooling. Previous isostatic fill procedures were improved in two ways to accommodate varying bulk densities or powder compositions. First, during the isostatic fill procedure, the powder fill is subject to both a high frequency vibration and a high amplitude, low frequency impulse. The combination of these two inputs is critical to ensure polymer bonded explosives pack to consistent densities. Second, unlike in conventional practices, the fill rate is kept constant throughout the entire fill process and the mold is completely filled by the time the required powder mass has been dispensed.

First claim

What is claimed is:

1. A method for filling a projectile case with energetic material, the method comprising the steps of: providing the energetic material in powder form; filling a mold of an isostatic pressing tool at a constant rate while simultaneously subjecting the mold to a high frequency low amplitude vibration and a low frequency high amplitude impulse; isostatically pressing a column of the powder to create a pre-formed billet; placing the pre-formed billet in the projectile case wherein the interior cavity of the projectile case has a larger maximum diameter than an opening of the projectile case; axially pressing the pre-formed billet in the projectile case thereby increasing the density of the pre-formed billet; and filling the projectile case using only the one pre-formed billet;
wherein the energetic material is filled into the mold via a fill assembly comprising a fill hose, a nozzle and a flow control device at the interface of the fill hose and the nozzle, and
wherein the flow control device is configured such that the energetic material is provided from the fill hose to the mold via the nozzle at a constant rate throughout an entire fill process and such that the time required to fill the mold is equal to the time required to dispense the energetic material.

2. The method of claim 1 wherein the step of providing the energetic material in powder form further comprises providing the energetic material in powder form with variation in bulk powder density.

3. The method of claim 2 wherein the bulk powder density varies within a range of plus or minus five percent from a median density.

4. The method of claim 1 wherein the isostatic pressing tool further comprises one or more vibration motors and an impulse generator.

5. The method of claim 1 wherein the mold is subjected to a high frequency low amplitude vibration in a range of 100 Hertz to 900 Hertz.

6. The method of claim 1 wherein the isostatic pressing tool further comprises one or more slapper devices.

7. The method of claim 1 wherein the mold is subjected to a high amplitude low frequency impulse in a range of 2 Hertz to 3 Hertz.

8. The method of claim 1 wherein the flow control device is selected from the group consisting of an orifice and a valve.

Assignees

• Us Gov Sec Army
• Us Army

Inventors

• Sequeira John
• Swaszek Sean

Classifications

• F42B33/0285

  Measuring explosive-charge levels in containers or cartridge cases; Methods or devices for controlling the quantity of material fed or filled (F42B33/004 takes precedence; controlling the quantity of material fed in packaging B65B3/26) · CPC title

• F42B33/0257 Primary

  by vibration compacting · CPC title

• F42B33/001

  Devices or processes for assembling ammunition, cartridges or cartridge elements from parts · CPC title

• B65B3/34

  by timing of filling operations · CPC title

• F42B33/02

  Filling cartridges, missiles, or fuzes; Inserting propellant or explosive charges {(F42B33/004 takes precedence)} · CPC title