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Large Caliber Steel Cartridge Case

Description:

DIRECT TO PHASE II

TECHNOLOGY AREA(S): Weapons

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), which controls the export and import of defense-related material and services. Offerors must disclose any proposed use of foreign nationals, their country of origin, and what tasks each would accomplish in the statement of work in accordance with section 5.4.c.(8) of the solicitation.

OBJECTIVE: Develop a manufacturing technique that economically manufactures large caliber steel cartridge cases within required dimensional and mechanical parameters.

DESCRIPTION: The Navy uses 5-inch steel cartridge cases, which are manufactured using a deep draw production process, in some of its guns. The deep draw production process and the associated equipment are economical for high volume production but not for low volume production. The Navy is seeking innovative manufacturing techniques or processes that enable equitable manufacturing of the cartridge cases in low volumes. A maximum total cost is targeted at $800/unit for an initial production year run of 8,000 units. Subsequent year target cost is $350/unit for additional production runs of 8,000 units/year. Specifications for the shell casing will be provided upon contract award.

The present deep-draw steel cartridge case is one with specific mechanical properties built into the case which the new manufacturing process must meet. These properties are such that the steel will expand to the gun chamber surface and obturate satisfactorily during firing, but must still be resilient enough to recover after firing to allow for extraction. The required mechanical properties (i.e., strength, expansion, and contraction capabilities and metal integrity) are produced and controlled by judicious use of heat-treating and metal-forming techniques during casing production. These properties are required to be varied along the entire length of the case.

When a gun is fired, the propelling charge is ignited and the resultant internal gas pressure causes the case to expand to the diameter of the gun chamber, after which case and gun expand together. The gun expands elastically; the case expands elastically and plastically. The elastic characteristic of the gun is fixed and both the elastic and plastic characteristics of the case are functions of the case material's composition and yield strength. The taper profile on the 5-inch cartridge case prevents net shape forming via conventional flow forming techniques. One would neither be able to remove the part from the mandrel nor be able to flow form the exterior taper (standard flow forming techniques create straight walls). Furthermore, the required material properties along the length of the case have been difficult to reproduce.

While prior research has shown flow forming as a potential technical and economical long term solution, the current processes in both metal forming and heat treating technologies are inadequate. Economically, flow forming is a slower process and generally not as efficient. An innovative manufacturing technique could include pre and post machining, and heat treating as an effective solution. The innovative manufacturing techniques or processes developed under this topic will likely have application in the Army’s and Navy’s family of large caliber ammunition (e.g. Navy 76mm, 5-inch, and 155m; Army 105mm cannon and 105mm artillery).

PHASE I: The offeror will develop an approach for innovative manufacturing techniques that meets the parameters of producing a 5-inch cartridge case. The approach must be economical for low and high production yields of the cartridge and demonstrate a feasible path to fabricating a conforming cartridge case as described in the description.

PHASE II: The offeror will develop, demonstrate, and validate the approach developed during Phase I to produce a prototype of the innovative manufacturing technique. The process will be validated through performance of risk reduction prototype testing on samples as necessary to mature and validate the manufacturing technique or process. At least two rounds of full scale prototypes will be fabricated and analyzed for metallurgy and function, including case to munition interface and handling equipment operation. A final delivery of 50 cartridge cases will be delivered for demonstration testing by the Naval Gunnery Program Office.

DIRECT TO PHASE II (DP2): Offerors interested in submitting a DP2 proposal in response to this topic must provide documentation to substantiate that the scientific and technical merit and feasibility described in the Phase I section of this topic has been met and describes the potential commercial applications. The offerors related DP2 proposal will not be evaluated without adequate PH I feasibility documentation. Documentation should include all relevant information including, but not limited to: technical reports, test data, prototype designs/models, and performance goals/result. Please read the OSD SBIR 16.2 Direct to Phase II Instructions.

PHASE III DUAL USE APPLICATIONS: The offeror will demonstrate the production of the innovative manufacturing technique for 5-inch steel casings that conform to the casing requirements. The offeror is expected to provide 100 production representative 5-inch shell casings for qualification tests to be conducted by the Naval Gunnery Program Office in the Major Caliber Program Production of shells. Nominally, this testing will proceed similar to a First Article Test and live fire tests using complete propelling charges. The technology developed under this topic has potential use in both Navy and Army large-caliber guns.

  • AMCP 706-247 Engineering Design Handbook: Ammunition Series Section 4: Design for Projection, Jul 1964.
  • AMCP 706-249 Engineering Design Handbook: Ammunition Series Section 6: Manufacture of Metallic Components of Artillery Ammunition, Jul 1964.
  • Felmley,T and McHenry, J. “Flow Formed Cartridge Testing” National Center for Excellence in Metalworking Technology. 08 Jan 1998.
  • Creeden, T.P., Bagnall, C, McHenry, J.C., Gover, J., Kovalcik, C.M., Dong, H., and Ucok, I. Optimized Flow-Formed Steel Cartridge Casings: Product and Process Analysis. 30 Jun 2000.
  • Onesto, E.J. and Bagnall, C. “Optimized Flowformed 5-inch/54 Steel Cartridge Cases.” 02 Jan 2002.

KEYWORDS: flow forming; deep draw; large caliber; steel cartridge case; major caliber; heat treating

 

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