Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
  • F42B12/72—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material
  • F42B12/76—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material of the casing
  • F42B12/78—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material of the casing of jackets for smallarm bullets ; Jacketed bullets or projectiles
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F42—AMMUNITION; BLASTING
  • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
  • F42B12/00—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material
  • F42B12/72—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material
  • F42B12/74—Projectiles, missiles or mines characterised by the warhead, the intended effect, or the material characterised by the material of the core or solid body

Definitions

• the invention applies to the method of bonding cores and jackets of bullets of a variety of types and calibres of hunting rifle ammunition and ammunition for special civilian applications.
• caliHrds Having the length-to-calibre ' ratio ' i df 3 to 3v1 ⁇ 4, which are Kabl tb the roih ⁇ mothent as they pass through the tissue - they rotate and fragmentize, such as the feared bullets .223 Remington; used in 1 the ; ammunition ; of ' 3 ⁇ 43 ⁇ 4 1 16 rifles in the Vietnam War, as Weil as : all the
• Firing into suitable simulants is conducted in order to evaluate the wounding effect.
• the measure of the wounding effect is as perfect as possible and highly reproducible bullet disintegration, when the bullet reshapes to resemble a "mushroom" - a process called mushrooming, along with the shape and depth of the wound channel.
• Gelatine and glycerine soap are exclusively used as simulants. Transparency is an advantage of gelatine while elasticity is its disadvantage as; it disables more specific determination of the course of the bullet energy transfer during me penetration, for the wounc? channel closes. It is vice versa in case of glycerine soap. , f ⁇ ;
• jacketed bullets which have been used for over 100 years, is generally known and is based on encasing the core made of lead or lead alloys into a jacket made most commonly of brass, tombac or so called tombac plate.
• the encasing is performed mechanically by pressing the core into the jacket and subsequently by securing the core to prevent it from dropping out, e.g. by hemming.
• the bullet rear part is jacketed as well. If hollow cavities are formed in these bullets, which bullets are designated as HP - hollow point bullets, an undesirable phenomenon occurs as these bullets pass through the tissue or simulant.
• Soldering is one of the oldest and at the same time most efficient methods of joining two identical or different metal materials - called base materials, with the use of another metal - solder, whose composition can be significantly different from the base material, unlike welding.
• a joint strength that is close to the base material strength can be achieved by appropriately selecting the base material and solder composition and by optimizing soldering conditions.
• Both physical-chemical and metallurgical processes can operate in soldering, which processes involve for instance the solder material diffusion into the base material and vice versa, mutual dissolution of both materials resulting in formation of solid solutions, or even reactions of both materials that produce intermetallic compounds.
• solder adhesion to the base material as well as the solder spread factor and capillarity are a prerequisite of solderability bf both rnaterials.
• Applicable solders include both pure metals, whose range of choice for soldering up to 450 °C is considerably limited to metals with 'a very low melting point such as Bi or Sn, and tens of known alloys of Pb/Sn/Bi/Sb/Ag etc.
• solderability of two pure metals can be easily estimated from binary 1 equilibrium diagrams, where three basic cases may occur - the metals are absolutely non-wettable, or the metals form interrnetallic compounds, or the metals form eutectic, which is the optirnum precondition for solderability. From this point of view, Pb has to be considered as non-soldefable in respect of Cu and Zn or Cu/Zn alloys.
• Solderability can of course be significantly enhanced by alloying with other metals, tens of types of "lead” solders are known today, and particularly by using flux, which is necessary in all cases when soldering is conducted without protective atmosphere.
• the main functions of flux include elimination of metal oxides, considerable reduction of solder surface tension, and thus increasing the solder wettability and spread factor and protection of soldered joint against further oxidation.
• any inorganic or organic compound that is able to dissolve the microscopic layer of oxides sufficiently quickly can serve as flux.
• the initial ZnCl 2 reacts in a similar fashion. If these- compounds cannot be quantitatively eliminated from the joint, they can cause the joint corrosion, and thus deterioration; of its mechanical properties. Therefore, corrosive fluxes are not recommended for soldering deep or capillary joints. To the contrary; e:g. Cu or Zn salts o organic acids, such as gum rosihs, are non-hygroscopic, insoluble and non-corrosive compounds.
• the non-corrosive fluxes of the gum rosin type which is a non-toxic compound, inert in the solid state and qualified as an irritant only according to the most recent categorization, which means that a standard type of gloves and a respirator suffice for protection
• the ' ammunition manufacturers involved in the "bonding" process use exclusively ZnCl 2 based corrosive fluxes; This can be caused by a lack of mastery or lack of knowledge of the technology of applying powdered fluxes in mass production compared to the seemingly simple technology of using solutions or suspensions of the said highly corrosive and toxic compounds. ;
• the solution according to the invention describes a simple and very efficient bullet soldering technology, using a specifically developed method of application of non-toxic powder gum ri>sin type fluxes, which method is incomparably friendlier to the environment and places only minimum demands on the occupational hygiene and safety;
• the modification of the soldering process lies in the fact that during this process joining of two base materials with conventional solder does take place. But joining two base materials with a conventional solder instead it involves joining only two materials of which one fulfils the role of the solder and base rriaterial proceeds at the same time.
• the said material is the proper bullet core, which must meet three essential requirements for this purpose:
• piire metal Pb piire metal Pb, eutectic alloys having the least possible content of the alloying agent - Pb / Ag 2.5 % or alloys of very close composition - Pb / Ag 0.3 - 215 6 ⁇ , and non-eutectic alloys having a composition close to pure metals - Pb / Sn 0.1 - 7 %, where the amount of Sn of approximately 7 % proved to : be the limit amount in terms of undesirable increase in hardness and decrease in flow.
• the equilibrium diagram of Pb/Sn alloy higher contents of Sn occur in the extended area of so called slush state between liquid and solid.
• Pb/Sb alloys which are frequently us6d for production of Pb bullets or cores, are not too suitable for soldering purposes, except for very small amounts of Sb, for the reason of the capacity of Sb to form brittle intermetallic compounds with Zn in the bullet jacket.
• Flux application is performed by the method according' to the invention in rotating drums made' bf any material, but best made of a metal material, resistant to the temperatures of up to approximately 300°C.
• the drams a e bf a cylindrical shape with smooth inner surface and they are riot fitted with any inner partitions or projections.
• the cores, preheated to the temperature of approximately 200 - 250°C, are poured into the rotating drum and a calculated dose of powder flux is immediately added.
• the flux particles adhere to and melt on the surface of the cores and form a thin uniform layer on the cores by influence of the drum rotation.
• the cores cool down belbw the flux melting point within several minutes, depending on the thermal capacity of the batch and the drum thermal conductivity, arid the cores can be poured onto a metal sieve, where t ey are spread and left to cool down to the ambient temperature.
• Applicable fluxes include Various types of gum rbsin, including its hydrogenated or polymerized form, as well as sorne kinds of solid organic acids, both in the mixture with gum rbsin and alone. These compounds must meet several fundamental conditions: th melting point should range from 100 to 250 °C and the melting must not be accompanied by decomposition to toxic products or by decarboxylation. If a mixture of two or more substances is used, their melting points should be as close as possible and the constituents must not exhibit any adverse reaction in the melted state. Some of aliphatic saturated dicarboxylic acids such as gtataric acid, adipic acid, pimelic acid, azelaic acid, sebacib acid etc. can be recommended from organic acids. !
• the cores that have been coated with a suitable flux in this fashion are subsequently mechanically loaded into the bullet jackets, whereby the semi-finished product is ready for soldering.
• the resin layer on the core acts as a sealantj the cores are, after having been
• the proper soldering can' be performed by standard methods, for instance in preheated metal blocks, in electric furnaces, using electromagnetic induction, etc.
• a regular conical shape of the core is formed 1 by influence of high shrinkage of Pb, which shape serves as a visual proof of a perfect soldered joint.
• Due to the extremely low hardness of unalloyed Pb bullets having these cores exhibit maximum disintegration - "mushrooming".
• the process of the bullet controlled disintegration can be regulated in a wide range. 1 ⁇ 3 ⁇ 4
• an applying drum comprisin a steel cylindrical vessel having the volume of 5 1, driven by an electric motor through a transmission mechanism* having a speed control option and inclination angle adjustment option and equipped with a dumping mechanism, an inclination angle of approximately 30 ° and rotation speed of approximately 60 rpm are set.
• 200 - 300 cores for manufacture of 9 mm Luger JHP bullets are poured into the drum, which cores are preheated to approximately 200°C, and a calculated dose of rosin gum powder flux is immediately added so that the consumption is approximately 2.5 - 3 mg per 1 square centimetre of the surface area, that is 2 - 2.5 g per 200 cores. Uniform wetting of all cores with the melted flux occurs immediately.
• the batch temperature decreases to such value that the flux adhesion to the cores is enhanced, and the cores start mix up in the drum rotation direction.
• This phase lasts for several minutes and depends on the thermal conductivity and thermal capacity of both the drum and the batch. Pb alloys have different thermal conductivity and specific heat.
• the adhesion of the cooling down flux increases to the value when the cores, start to conglomerate, the operation is interrupted and the cores are poured, onto a prepared metal sieve, where they are uniformly spread and left to cool down to the ambient temperature. After cooling down, the cores are ready for the subsequent, above-said operations.
• the solution according to present invention can be utilized for mass production of a variety of types and calibres of jacketed bullets, which are suitable for loading into all sorts of hunting ammunition and civilian ammunition designed for special applications.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• General Engineering & Computer Science (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2010
  • 2010-10-27 CZ CZ2010-783A patent/CZ306513B6/cs unknown
• 2011
  • 2011-10-26 WO PCT/CZ2011/000105 patent/WO2012055381A2/en active Application Filing
  • 2011-10-26 EP EP11813862.7A patent/EP2633263A2/de not_active Withdrawn

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