US3749023A - Inyl acetal instantaneously completely combustible cartridge case member of polyv - Google Patents

Inyl acetal instantaneously completely combustible cartridge case member of polyv Download PDF

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Publication number
US3749023A
US3749023A US00163287A US3749023DA US3749023A US 3749023 A US3749023 A US 3749023A US 00163287 A US00163287 A US 00163287A US 3749023D A US3749023D A US 3749023DA US 3749023 A US3749023 A US 3749023A
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United States
Prior art keywords
foam
polyvinyl acetal
case member
cartridge case
instantaneously
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Expired - Lifetime
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US00163287A
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English (en)
Inventor
K Kawaguchi
K Takahashi
H Yamazaki
Y Takeda
H Kazama
M Ono
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Technical Res & Dev
TECHNICAL RESEARCH AND DEVELOP INST JA
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Technical Res & Dev
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B5/00—Cartridge ammunition, e.g. separately-loaded propellant charges
    • F42B5/02—Cartridges, i.e. cases with charge and missile
    • F42B5/18—Caseless ammunition; Cartridges having combustible cases
    • F42B5/181—Caseless ammunition; Cartridges having combustible cases consisting of a combustible casing wall and a metal base; Connectors therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
    • B29C44/10—Applying counter-pressure during expanding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
    • B29C44/34—Auxiliary operations
    • B29C44/56—After-treatment of articles, e.g. for altering the shape
    • B29C44/5627—After-treatment of articles, e.g. for altering the shape by mechanical deformation, e.g. crushing, embossing, stretching
    • B29C44/5636—After-treatment of articles, e.g. for altering the shape by mechanical deformation, e.g. crushing, embossing, stretching with the addition of heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B5/00—Cartridge ammunition, e.g. separately-loaded propellant charges
    • F42B5/02—Cartridges, i.e. cases with charge and missile
    • F42B5/18—Caseless ammunition; Cartridges having combustible cases
    • F42B5/188—Manufacturing processes therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F42—AMMUNITION; BLASTING
    • F42B—EXPLOSIVE CHARGES, e.g. FOR BLASTING, FIREWORKS, AMMUNITION
    • F42B5/00—Cartridge ammunition, e.g. separately-loaded propellant charges
    • F42B5/26—Cartridge cases
    • F42B5/30—Cartridge cases of plastics, i.e. the cartridge-case tube is of plastics
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S102/00—Ammunition and explosives
    • Y10S102/70—Combustilbe cartridge

Definitions

  • ABSTRACT ment filler selected from two groups, i.e., fibers of the said resins and a cloth of said resins, prior to being compressed, the said foam can have an increased strength.
  • a bind-er of a synthetic resin after compression further increased strength and hardness of the foam is obtained.
  • the outer surface of the case member may be given an easily combustible thin film and also a damp-proof thin coating on top of the said film.
  • This cartridge case member does not combust spontaneously during handling or during transportation since it combusts at a high temperature. This case member leaves no solid combustion residues at the time of combustion within a firearm.
  • the aforesaid cartridge case members are suitable for manufacture on a mass production basis and the cost of manufacture can be lowered greatly.
  • the present invention is concerned with a cartridge case for rounds of firearms, and more particularly, it relates to a hollow cartridge case member which will combust completely instantaneously when ignited by the propellant contained therein before the shot is discharged from the muzzle of the firearm, without leaving any solid residues of combustion.
  • the present invention further relates to a method of manufacturing the cartridge case member of the type described.
  • cartridges which are currently used are made of a metal such as brass or steel. These metallic cartridge cases can resist the high pressure produced in the cartridge chamber at the time of firing. Such a cartridge case is structured so that the highly pressurized gases produced within the cartridge chamber are prevented from leaking through the bottom of the chamber. Thus, these cartridge cases of the prior art function as they should.
  • the metals with which the cartridge cases of the prior art are made are rather expensive and could be difficult to procure at any emergency time, and this is especially so with brass.
  • weapons such as tank and wheeled guns are designed so that firing is performed within a narrow space of the chamber or turret.
  • Another object of the present invention is to provide a new cartridge case member which satisfies substantially all of the aforesaid requirements by being constructed with an instantaneously completely combustible foam of a synthetic resin selected from the group consisting of polyvinyl acetal, polyurethane and polystyrene which become hard enough when molded into a cartridge case.
  • Still another object of the present invention is to provide a new cartridge case member of the type described, which has a highly enhanced mechanical strength and hardness by the inclusion therein of a reinforcement material which may be a reactive lower polymeric binder and/or polyvinyl acetal fibers and/or a coarse polyvinyl acetal cloth.
  • a reinforcement material which may be a reactive lower polymeric binder and/or polyvinyl acetal fibers and/or a coarse polyvinyl acetal cloth.
  • Yet another object of the present invention is to provide a new cartridge case member of the type described, which in addition to the features mentioned above is damp-proof due to the fact that the surface of the said case member is coated with a damp-proof material.
  • a further object of the present invention is to provide a simple and easy and low-cost method for producing the new cartridge case member which satisfies substantially all of the aforesaid requirements by being constructed with an instantaneously completely combustible foam of a synthetic resin of the type described which is hard enough when molded into a cartridge case member.
  • a still further object of the present invention is to provide a simple, easy and low-cost method for producing the new cartridge case member of the type described above which possesses an enhanced mechanical strength and hardness by the inclusion therein of a reinforcement material, i.e., a reactive lower polymeric binder and/or polyvinyl acetal fibers and/or a coarse polyvinyl acetal cloth.
  • a reinforcement material i.e., a reactive lower polymeric binder and/or polyvinyl acetal fibers and/or a coarse polyvinyl acetal cloth.
  • a yet further object of the present invention is to provide a simple, easy and low-cost method for producing a new cartridge case member of the type described which in addition to the features mentioned above is moisture-proof by the fact that its surface is coated with a moisture-proof material.
  • FIG. 1 is a side elevational view, partly in section, showing an example of a cartridge case having an instantaneously completely combustible cartridge case member of the present invention.
  • FIG. 2 is a longitudinal sectional view of a compression-molding apparatus suitable for use in performing an excessive compression of a foamed material, representing a first step of the manufacturing method of the present invention.
  • FIG. 3 is a longitudinal sectional view of a heating apparatus suitable for use in performing heat-expansion of the compressed foamed material, representing a second step of the method of the present invention.
  • FIG. 4 is a chart showing the results of ignition point tests conducted on the cartridge case members produced accordinging to the method of the present invention as compared with that of the ignition point of the propellant.
  • the present invention contemplates the provision of a new cartridge case member which is instantaneously completely combusted at the time of firing and which satisfies substantially all of the aforesaid requirements of a cartridge case.
  • the present invention is also concerned with a method for producing this new cartridge case member.
  • the present invention has been worked out based on the discovery that cartridge case members made of foams of various kinds of synthetic resins can satisfty the above-mentioned requirements to a certain degree.
  • Foams of synthetic resin may be divided roughly into two types, one of which has pores or cells which are sealed from each other and the other is such that the pores of cells intercommunicate with each other.
  • foams having the intercommunicating pores are more desirable for use as the material of instantaneously completely combustible cartridge case member from the viewpoint of enhanced combustibility of same.
  • foams having independent cells can be as equally effectively used as those of the intercommunicating type if they have a sufficiently large porosity and if the cell walls have an effectively small thickness.
  • Foams having thin sealed cells will break easily into fine fragments upon being exposed to a high temperature and a high pressure within the cartridge chamber so that the surface area of the cells per unit weight will suddenly increase to a tremendous extent, enabling the whole of the foam to combust instantaneously.
  • foams of almost all kinds of synthetic resins and cellulose derivatives as the material of the instantly completely combustible cartridge case member of the present invention provided that they have a desirable condition of pores of cells.
  • polyvinyl acetal, polyurethane and polystyrene has been found suitable.
  • polyvinyl acetal is found to be especially suitable for the aforesaid purpose. A major reason therefor may be explained as follows.
  • Foam of polyvinyl acetal is of a structure which is characterized by the fact that fine fibrous polyvinyl acetal product which is produced from a reaction between polyvinyl alcohol and aldehyde in an aqueous solution forms a three dimensional reticular structure of molecules. Since polyvinyl acetal is thermoplastic by nature, it can be molded easily by subjecting same to compression-molding while being heated. On the other hand, polyvinyl acetal having an acetalization degree of the order of 65-86 percent tends to become pliant and swollen when heated with steam. This nature of polyvinyl acetal is utilized to give a desired configuration.
  • Foam of polyvinyl acetal which is suitable for use as the material of cartridge case member of the present invention is of the following conditions, i.e., an average polymerization degree of l,000-2,500, a polyvinyl alcohol to polyvinyl acetal intermolecular rearrangement ratio or acetalization degree of 65.0-86.0 percent, an apparent specific gravity of 0.06-0.12 and a porosity of 90.0-95.5 percent.
  • Un-processed foam of polyvinyl acetal which is available as the material of the instantaneously completely combustible cartridge case member of the present invention, like foams of polyurethane and polystyrene, can have an enhanced mechanical strength and hardness by first subjecting it to a compression process and then blending therein a binder which may be either a polymer or a reactive intermediate product of a lower polymerization degree in an amount 30 percent or less, by weight, relative to the gross weight of polyvinyl acetal.
  • a binder which may be either a polymer or a reactive intermediate product of a lower polymerization degree in an amount 30 percent or less, by weight, relative to the gross weight of polyvinyl acetal.
  • this polyvinyl acetal foam can be improved further to suit for practical use by including, in the polyvinyl acetal, a reinforcement filler which is one or both of polyvinyl acetal fibers and a coarse polyvinyl acetal cloth prior to the compressing process.
  • reference numeral 1 represents generally a hollow cartridge case.
  • Numeral 2 represents an instantaneously completely combustible cartridge caseconstituting hollow member.
  • This cartridge case member 2 is made of polyvinyl acetal foam. In order to enhance the mechanical strength of this member 2, the latter contains uniformly throughout therein polyvinyl acetal fibers 3, and in addition, the case member 2 has a coarse polyvinyl acetal cloth 4 which is embedded in the member 2 at a position close to the inner surface thereof in such a way that the surface of the cloth is substantially exposed to the external atmosphere and visible externally.
  • Numeral 5 represents a bottom member made of a metal.
  • Numeral 6 represents a hole formed through the bottom portion of said bottom member 5 for the attachment of a fuse.
  • Numeral 7 represents a shoulder portion.
  • Numeral 8 represents a shot or shell.
  • Numeral 10 represents a layer of bonding agent with which the lower portion 9 of the said case member 2 is securely bonded to the upper portion 9
  • the instantaneously completely combustible hollow cartridge case member 2 having the aforesaid structure is made with a polyvinyl acetal foam having numerous very fine intercommunicating pores throughout the entirety thereof, and accordingly, the case member 2 is of a very large surface area. It should be understood that the length of time consumed from the time the propel, lant contained in the cartridge case starts to combust till the time the shot is discharged from the muzzle of a firearm is of the order of several milli-seconds.
  • the case member 2 made with the aforesaid materials and having the abovementioned structure will be exposed during such a momentary short period of time to a very high temperature and a very high pressure produced from the combustion of the propellant, and will be combusted completely instantaneously, neither leaving any solid.
  • this case member 2 will not combust spontaneously when a round having a cartridge case made with this case member 2 is charged in the heated cartridge chamber of a firearm during successive firing. Furthermore, as will be discussed later, this case member 2 is of a mechemical strength necessary and sufficient for a satisfactory cartridge case member.
  • the cartridge case member 2 is made of a basic material which is polyvinyl acetal foam. Accordingly, the case member 2 is of elasticity of an appropriate degree.
  • this case member 2 contains polyvinyl acetal fibers 3 distributed uniformly throughout its porous structure and also it has a coarse polyvinyl acetal cloth 4 embedded in the entire surface region of the polyvinyl acetal foam, and in addition, the shoulder portion of this case member 2 is of a greater thickness than the remaining portions. Therefore, the cartridge case member 2 is especially of an increased strength against impact. Cartridge case members made according to the present invention and having the aforesaid structure were subjected to a strength test,
  • A represents polyvinyl acetal foam
  • B represents polyvinyl acetal fibers
  • C represents coarse polyvinyl acetal cloth
  • an aspect of the present invention concerns a method for manufacturing, in a reasonable manner, an instantaneously completely combustible hollow member of a cartridge case having the aforesaid features. More specifically, it concerns a method for maufacturing cartridge case members of the type described by the use of a hollow cylindrical polyvinyl acetal foam containing therein at least one of the following two kinds of reinforcement fillers, i.e., polyvinyl acetal fibers and a coarse polyvinyl cloth, and by first excessively compressing this cylindrical foam on a male mold member of a compression molding apparatus with a pressurized fluid applied onto the external circumference of the cylindrical foam radially against the surface of the mold member and then expanding, with heat, the resulting compressed cylinder which is then positioned in the space between an inner male mold member and an outer female mold member of a separate expansion molding apparatus after applying an appropriate amount of humidity to the foam, to thereby urge this foam tightly against the inner surface of the outer female mold member.
  • a modified method of the present invention comprises the use of a hollow cylindrical polyvinyl acetal foam containing therein at least one of the reinforcement fillers, i.e., polyvinyl acetal fibers and a coarse polyvinyl cloth, and by first excessively compressing this cylindrical foam on a male mold member of a compression mold with a fluid pressure applied onto the external circumference of the cylindrical foam radially against the surface of the mold member, then expanding, with heat, the resulting compressed cylindrical foam which is then positioned in the space between an inner male mold member and an outer female mold member of a separate mold after applying an appropriate amount of humidity to the foam, to thereby urge this foam tightly against the inner surface of the outer female mold member, thereafter treating the resulting molded cylindrical foam with a synthetic resin, and the forming an easily combustible thin film on the entire outer surface of the treated cylindrical foam by applying a thixotropic solution of a low concentration containing nitrocellulose and a thixotropic agent.
  • H6. 2 shows a longitudinal central sectional view of a compression molding apparatus utilizing a pressurized fluid.
  • reference numeral l3 represents a male mold member having generally a cylindrical configuration. This male mold member has a central longitudinal gas-passage channel llll communicating with the outside of this mold member 13 and a plurality of radial gas-passage channels lllla opening at one end to the circumferential surface of the mold member and communicating at the other end with the said central longitudinal gas-passage channel El, and also has a closed region 12.
  • Numeral 15 represents a pressureresistant cylindrical frame having an inlet lid for introducing a pressurized fluid a pressure medium into the space inside this pressure-resistant cylindrical frame if.
  • the fluid which may be used in the present invention includes water, oil and gas such as air.
  • a hollow cylindrical foam piece 17 covered externally with an elastic cover M such as a rubber bag is mounted on the male mold member 33 and is set in the mold as shown in FIG. 2.
  • a pressurized fluid M is introduced into the space within the pressure-resistant cylindrical frame 15 of the mold through the pressurized fluid inlet 18 from an appropriate compression pump to compress the hollow cylindrical foam piece 17 radially against the circumferential surface of the male mold member 13.
  • This hollow cylindrical foam piece 17 is the material for producing an instantaneously completely combustible hollow cartridge case member 2 shown in FllG. i.
  • This cylindrical foam piece 17 is made with a principal material which is polyvinyl acetal foam of an acetalization degree of 65-86 percent and having numerous intercommunicating fine pores throughout its structure and having polyvinyl acetal fibers 3 distributed uniformly throughout therein and also having a coarse polyvinyl acetal cloth 4 embedded close to one surface of the foam piece 17.
  • a principal material which is polyvinyl acetal foam of an acetalization degree of 65-86 percent and having numerous intercommunicating fine pores throughout its structure and having polyvinyl acetal fibers 3 distributed uniformly throughout therein and also having a coarse polyvinyl acetal cloth 4 embedded close to one surface of the foam piece 17.
  • the pressure of the fluid 14 is introduced into the space inside the cylindrical frame 15 by an appropriate means. whereupon, the elastic cover 16 will be caused to tightly contact the external circumferential surface of the hollow cylindrical foam piece 17 to compress this foam piece 17 evenly radially against the external circumferential surface of the male mold member 13.
  • the pressure of the fluid 14 is controlled so that the molded hollow cylindrical foam piece 17 will have an outer diameter appropriately smaller than the inner diameter of the outer mold member 20 shown in FIG. 3.
  • the foam piece 17 which has been compression-molded in the aforesaid manner is indicated by a reference numeral 21 in FIG. 3.
  • the pressure can be applied evenly to the entire outer surface of the hollow cylindrical foam piece 17.
  • the foam piece 17 so as to have a uniform desired thickness and a uniform desired density throughout the entirety thereof with no difficulty and without undesirable partial compression and density which would tend to take place in heat-compression molding as will be discussed below.
  • the heat-compression molding comprises the steps of first inserting a hollow cylindrical polyvinyl acetal foam piece in a hollow cylindrical female mold member so that this foam piece is in tight contact with the inner face of the female mold member, thereafter supplying excessively heated steam having a temperature of 120-1 C onto the tightly contacting surface of the foam piece externally of the female mold member through numerous small perforations formed through the wall of the female mold member to cause the steam to be absorbed in the porous structure to sufficiently soften same, thereafter inserting a male mold member heated to a temperature substantially the same as that of the steam into the hollow space of the foam piece up to a predetermined position by means of, for example, a hydraulic pressing device, then passing steam for l-2 minutes to the foam piece to remove and correct any deformation of the foam piece, thereafter stopping the supply of the steam, and supplying dry gas such as air heated at 120-1 30 C to dry the damp foam piece until the residual moisture in the foam structure drops to two percent or less.
  • the said steam and the said dry air invariably pass through the porous structure and are discharged from a gas outlet provided in the end of each of these two mold members.
  • a gas outlet provided in the end of each of these two mold members.
  • foam piece will have a difference in density between its inner surface region and its outer surface reg on. Also, the surfaces of the foam piece and their ad acent regions will show an injury in the pore structure, which leads to a much lowered combustibihty.
  • FIG. 3 is a longitudinal central sectional view of a heat-expansion molding apparatus.
  • reference numeral 20 represents an outer female mold member having a generally cylindrical configuration and having a heater 19.
  • a hollow cylindrical foam piece 21 which has been compression-molded by a pressurized fluid and which is mounted on a cylindrical inner male mold member 22 is inserted in an appropriate manner in the outer female mold member 20.
  • Numeral 23 represents a central longitudinal channel provided in the inner male mold member 22 for the passage of gas such as air.
  • Numeral 23a represents a rad al channel communicating at one end to the outer C11- cumferential surface of the inner male mold member and at the outer end with the central longitudinal gas channel 23.
  • the foam piece 21 which has been compressed with a pressurized fluid is impregnated with moisture to an appropriate degree, for example about 10 percent, prior to being heat-molded m this apparatus.
  • the outer female mold mem; ber 20 is heated at an appropriate temperature of C or higher, whereas the inner male mold member 22 is held at an appropriate temperature of 100 C or lower.
  • the hollow cylindrlcal foam piece 21 is still impregnated with moisture, and that, if this foam piece 21 is taken out from the heatexpansion apparatus at the said stage, there IS the fear that the foam piece 21 would tend to resume its initial size which it has prior to being compression-molded with a pressurized fluid. Accordingly, there arises the necessity for expelling the moisture from the porous structure. For this reason, a dry gas such as dry air is supplied onto the foam piece 21 through the gas channel 23 and accordingly through the radial gas channels 23a. After the moisture present in the porous structure has been removed substantially therefrom in this way, the heat-molded foam piece 21 is taken out from the heat-expansion molding apparatus.
  • a dry gas such as dry air is supplied onto the foam piece 21 through the gas channel 23 and accordingly through the radial gas channels 23a.
  • the weight of the foam piece 21 before being subjected to the method of the present invention 15 regulated so that the foam piece after heat-molding will have a density of 0.25-0.30 glcm which is a desirable condition of the foam piece suitable for use in the present invention.
  • a polyvinyl acetal foam is of inter-communicating pores, and has a tremendously large surface area of pores and has an acetalization degree of 65 -86 percent and contains therein polyvinyl acetal fibers and a coarse polyvinyl acetal cloth.
  • the foam piece 21 not only satisfies the requirements of an instantaneously completely combustible cartridge case member, but also permits compression-molding utilizing a pressurized fluid as well as permits heat-expansion molding. More specifically, the fact that the foam piece of polyvinyl acetal has an acetalization degree of 65-86 percent means that is has 35-14 percent of residual hydroxyl groups.
  • the moisture contained in the polyvinyl acetal porous structure will evaporate as it is brought into contact with the heated surface of the outer female mold member 20, and the resulting vapor of water will fill in the intercommunicating pores of the porous structure of stimulate the said residual hydroxyl group, thus rendering the foam piece soft and pliant.
  • the polyvinyl acetal foam piece has been in the compressed state which was produced previously in the first compression-molding step utilizing a pressurized fluid. Therefore, the foam piece 21 now gains the force to resume its initial configura tion and size which it has prior to being compressed. As a result, the foam piece 21 will tightly contact the inner circumferential surface of the outer female mold member 20.
  • This outer mold member 20 is of a temperature which is elevated to the decomposition point of the polyvinyl acetal foam.
  • the polyvinyl acetal foam is deprived of evaporation heat, and accordingly the polyvinyl acetal foam per se will never reach its decomposition point.
  • the aforesaid molding method of the present invention not only is advantageous from the economical point of view, but also contributes greatly to the easy combustibility of the cartridge case member. More specifically, if the case member is produced by relying on a heat-compression method, only those facial portions of the foam piece exposed to heat during the heatcompression process will be compressed, and only such portions will have an increased density ascompared with the remaining portions not having been heated nor compressed sufficiently. In other words, according to the heat-compression method, the molded porous structure will have a difference in density between its inner facial region and its outer facial region, and also lose its porous structure in the vicinity of its surfaces, developing blocked pores and accordingly having a substantially decreased surface ara of pores.
  • the foam piece obtained is of a uniform density and is free of the aforesaid disadvantage and inconvenience which are encountered in the products of heat-compression method, and moreover, the cartridge case member made with such a foam piece of the present invention will never give rise to the development of solid combustion residues which are encountered, at the time of firing, in cartridge case members produced by heatcompression method.
  • the aforesaid polyvinyl acetal foam which is molded according to the method of the present invention may have an increased strength and also may be kept from resuming its initial configuration and size after being molded, by treating same with a synthetic resin as will be discussed below.
  • polyvinyl acetal foam An increase in the strength of polyvinyl acetal foam is attained, as stated previously, by including in a polyvinyl acetal foam at least one, preferably both, of two kinds of reinforcement fillers, i.e., polyvinyl acetal fibers and a coarse polyvinyl acetal cloth. By doing so, the tensile strength and the anti-impact strength of the foam as a cartridge case member are both markedly increased as shown in Table 1.
  • a polyvinyl acetal foam not containing any reinforcement filler exhibits a tensile strength of about 10 kg/cm and an anti-impact strength of about 3.0 kg/cm/cm, as compared with the foam pieces containing one or both of the reinforcement materials, which exhibit a tensile strength of about 15-22 kg/crn and an anit-impact strength of about 5.0-6.0 kg cmlcm indicating an increase as great as about two times.
  • These reinforced foam pieces permit the rounds having a cartridge case made of such a case member to have a strength sufficient for use even when the rounds are dropped from a height of 50 cm onto a concrete floor.
  • the resulting foam not only will have an improved mechanical strength but also will hardly develop any deformation of its configuration after being compressed, and furthermore will have an enhanced water-proofness since hydrophilic hydroxyl groups contained in the foam are destroyed.
  • This treatment of polyvinyl foam with the aforesaid synthetic resin provides such a number of advantages as stated above
  • An example of the blended resin composition which satisfies these requirements is:
  • the polyvinyl acetal foam after being heat-expanded is impregnated with a solution having the aforesaid composition.
  • the isocyanate component of polyurethane By arranging the isocyanate component of polyurethane to be present therein in an excessive amount as mentioned above, it is possible to cause the residual hydroxyl group contained in the polyvinyl acetal foam to be united with the said. isocyanate group in an appropriate manner and to thereby obtain an instantly completely combustible cartridge case member having a three dimensional molecular structure.
  • the polyvinyl acetal foam which has been treated in the manner stated above has surfaces having numerous pores with a diameter of the order of microns, and are of good gas-permeability.
  • a film which is considered to be suitable for the aforesaid purpose in contributing to easy combustibility is such that it contains an explosive component such as nitrocellulose, or such that a thin film is formed only at the: surface of the foam without the resin penetrating into the porous structure through the pores present in the surface thereof.
  • under-coating consisting of a thixotropic solution of a low concentration, and to apply a water-proof coating on top of this undercoating.
  • under-coating composition is:
  • An under-coating solution having the aforesaid composition will exhibit thixotropy when this solution having a concentration of about five percent is heated and then quenched while being stirred.
  • This solution under this condition is creamy and is not tacky but is of a good ductility, so that it can be applied lightly on the surface of the porous structure without penetrating into the interior thereof.
  • This solution is applied with a brush to the surface of the porous structure. After being dried, a film of micron or less is obtained. This film, however, is of a poor water-proofness. Accordingly, after the surface pores of the porous structure have been blocked substantially by the application of the said under-coating solution thereto, a water-proof coating is given on top of the said under-coating.
  • the use of a vinylidene solution is suitable.
  • a pigment consisting of flaky aluminum powder will be effective in improving waterproofness.
  • the resulting porous structure can stand its exposure to a rainfall of not only the order of 4 il inches/hour, but also of the order of several times as great as that.
  • Cartridge cases having instantaneously completely combustible case members which were prepared'in the manner described above were subjected to a number of different tests. The result of these tests is as follows.
  • Test samples were tested by Amsler tester according to JlS-Z-2l 12.
  • the tensile strength of the case members was noted to be about 45 kg/cm'.
  • Test samples were tested by Sharpi impact tester according to JIS-Z-2202, with the result that their anti-impact strength was about 6 kg.cm/cm.
  • Samples were subjected to vibration at: amplitude 3.0 mm, frequency 1,500 cpm and acceleration 3.9 6., without being affected adversely.
  • the case member of the present invention can be molded quite reasonably so as to have a uniform density and uniform desired thickness.
  • the cartridge case member of the present invention leaves no appreciable residue at the time of firing.
  • the molded case member can have an enhanced strength and hardness by being treated with a synthetic resin. Moreover, it can have a very desirable waterproofness and combustiblity by being given at its surface a thin under-coating with a solution containing nitrocellulose and a thixotropic agent and being capable of exhibiting thixotropicity at a low concentration, and thereafter by forming a water-proof thin film on top of the said under-coating. Besides, the applications of these solutions is easy and needs no welltrained skill.
  • the cartridge case member 2 of the present invention desirably is provided at its bottom with a metal bottom member 5 having a small longitudinal length which is bonded by a layer of adhesive at its portion of juncture 9a to the corresponding portion of juncture 9 of the case member 2, in a manner as shown in FIG. 1, for establishing the enclosure of the gases produced at the time of firing.
  • the adhesive which is most suitable for use in these portions of juncture is an epoxy resin.
  • An instantaneously and completely combustible cartridge casing comprising: a hollow cylindrical casing made of thermoplastic polyvinyl acetal foam having uniformly distributed, intercommunicating fine pores and having a substantially uniform density in the range of from about 0.25 to about 0.30 g/cm, the casing being made from polyvinyl acetal foam having an average polymerization degree of from 1,000 to 2,500, an acetalization degree of from 65 to 86 percent, a porosity of from 90 to 95.5 percent and an apparent specific gravity of from 0.06 to 0.12, by compressing a hollow cylinder of said polyvinyl acetal foam on a male mold member by applying a uniform radially inwardly directed pressure on the entire external surface of the cylinder, then wetting the cylinder with water, heating the cylinder to expand same into contact with a female mold member and then drying the cylinder before removing it from the female mold member.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Paints Or Removers (AREA)
US00163287A 1970-07-23 1971-07-16 Inyl acetal instantaneously completely combustible cartridge case member of polyv Expired - Lifetime US3749023A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45063913A JPS4943437B1 (de) 1970-07-23 1970-07-23

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US3749023A true US3749023A (en) 1973-07-31

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US00163287A Expired - Lifetime US3749023A (en) 1970-07-23 1971-07-16 Inyl acetal instantaneously completely combustible cartridge case member of polyv

Country Status (7)

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US (1) US3749023A (de)
JP (1) JPS4943437B1 (de)
BE (1) BE770369A (de)
DE (1) DE2136750B2 (de)
FR (1) FR2103794A5 (de)
GB (1) GB1346828A (de)
SE (1) SE387434B (de)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895578A (en) * 1971-04-29 1975-07-22 Thiokol Corp Flare with adhesive liner
US3929074A (en) * 1974-04-05 1975-12-30 Us Navy Means for the elimination of a cartridge rim
US4159678A (en) * 1976-09-16 1979-07-03 Rheinmetall G.M.B.H. Propellant charge casing
US4535697A (en) * 1982-06-08 1985-08-20 Werkzeugmaschinenfabrik Oerlikon-Buhrle Ag Cartridge case and apparatus for producing the same
US5770815A (en) * 1995-08-14 1998-06-23 The United States Of America As Represented By The Secretary Of The Navy Ammunition cartridge with reduced propellant charge
US6600002B2 (en) 2000-05-02 2003-07-29 Alliant Techsystems, Inc. Chain-extended poly(bis-azidomethyloxetane), and combustible cartridge cases and ammunition comprising the same
FR2878025A1 (fr) * 2004-11-12 2006-05-19 Giat Ind Sa Munition sans douille et procede de montage d'une telle munition
US8763535B2 (en) 2011-01-14 2014-07-01 Pcp Tactical, Llc Narrowing high strength polymer-based cartridge casing for blank and subsonic ammunition
USD715888S1 (en) 2012-01-13 2014-10-21 Pcp Tactical, Llc Radiused insert
US8869702B2 (en) * 2011-01-14 2014-10-28 Pcp Tactical, Llc Variable inside shoulder polymer cartridge
US8875633B2 (en) 2011-01-14 2014-11-04 Pcp Tactical, Llc Adhesive lip for a high strength polymer-based cartridge casing and manufacturing method
WO2015154079A1 (en) * 2014-04-04 2015-10-08 Mac, Llc Method for producing subsonic ammunition casing
US9194680B2 (en) 2011-01-14 2015-11-24 Pcp Tactical, Llc Polymer-based machine gun belt links and cartridge casings and manufacturing method
US9335137B2 (en) 2011-07-28 2016-05-10 Mac, Llc Polymeric ammunition casing geometry
US9395165B2 (en) 2011-07-28 2016-07-19 Mac, Llc Subsonic ammunition casing
US9528799B2 (en) 2014-01-13 2016-12-27 Mac Llc Neck polymeric ammunition casing geometry
USD813975S1 (en) * 2015-08-05 2018-03-27 Mark White Low volume subsonic bullet cartridge case
US10254092B1 (en) * 2007-05-23 2019-04-09 Vista Outdoor Operations Llc Advanced muzzle loader ammunition
US10794671B2 (en) 2011-01-14 2020-10-06 Pcp Tactical, Llc Polymer-based cartridge casing for subsonic ammunition
US11448491B2 (en) 2018-07-30 2022-09-20 Pcp Tactical, Llc Polymer cartridge with enhanced snapfit metal insert and thickness ratios
US11913764B2 (en) 2017-04-19 2024-02-27 Pcp Tactical, Llc Cartridge case having a neck with increased thickness

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5124766U (de) * 1974-08-12 1976-02-23
DE2458877C2 (de) * 1974-12-12 1983-02-10 Deutsch-Französisches Forschungsinstitut Saint-Louis, Saint-Louis Verbrennbare Schutzhülle gegen thermische Einflüsse für Geschoßtreibladungen für automatische Waffen
JPS5178155U (de) * 1974-12-16 1976-06-21
JPS51149035U (de) * 1975-05-24 1976-11-29
JPS528649U (de) * 1975-07-02 1977-01-21
JPS5281945U (de) * 1975-12-16 1977-06-18
JPS53954U (de) * 1976-06-22 1978-01-07
DE2710451C2 (de) * 1977-03-10 1990-11-15 Rheinmetall GmbH, 4000 Düsseldorf Oberflächenschutzbeschichtung für Munition mit verbrennbarer Hülse bzw. hülsenlose Munition
JPS55151165U (de) * 1979-04-17 1980-10-31
FR2602040B1 (fr) * 1986-07-23 1988-11-10 Serat Perfectionnements apportes aux armes, ou systemes lanceurs, sans recul, de projectiles

Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3895578A (en) * 1971-04-29 1975-07-22 Thiokol Corp Flare with adhesive liner
US3929074A (en) * 1974-04-05 1975-12-30 Us Navy Means for the elimination of a cartridge rim
US4159678A (en) * 1976-09-16 1979-07-03 Rheinmetall G.M.B.H. Propellant charge casing
US4535697A (en) * 1982-06-08 1985-08-20 Werkzeugmaschinenfabrik Oerlikon-Buhrle Ag Cartridge case and apparatus for producing the same
US5770815A (en) * 1995-08-14 1998-06-23 The United States Of America As Represented By The Secretary Of The Navy Ammunition cartridge with reduced propellant charge
US6600002B2 (en) 2000-05-02 2003-07-29 Alliant Techsystems, Inc. Chain-extended poly(bis-azidomethyloxetane), and combustible cartridge cases and ammunition comprising the same
FR2878025A1 (fr) * 2004-11-12 2006-05-19 Giat Ind Sa Munition sans douille et procede de montage d'une telle munition
US10254092B1 (en) * 2007-05-23 2019-04-09 Vista Outdoor Operations Llc Advanced muzzle loader ammunition
US9599443B2 (en) 2010-07-30 2017-03-21 Pcp Tactical, Llc Base insert for polymer ammunition cartridges
US9989343B2 (en) 2010-07-30 2018-06-05 Pcp Tactical, Llc Base insert for polymer ammunition cartridges
US8763535B2 (en) 2011-01-14 2014-07-01 Pcp Tactical, Llc Narrowing high strength polymer-based cartridge casing for blank and subsonic ammunition
US8875633B2 (en) 2011-01-14 2014-11-04 Pcp Tactical, Llc Adhesive lip for a high strength polymer-based cartridge casing and manufacturing method
US11976911B2 (en) 2011-01-14 2024-05-07 Pcp Tactical, Llc Polymer-based cartridge casing for subsonic ammunition
US9194680B2 (en) 2011-01-14 2015-11-24 Pcp Tactical, Llc Polymer-based machine gun belt links and cartridge casings and manufacturing method
US9261335B2 (en) 2011-01-14 2016-02-16 Pcp Tactical, Llc Frangible portion for a high strength polymer-based cartridge casing and manufacturing method
US11353299B2 (en) 2011-01-14 2022-06-07 Pcp Tactical, Llc Polymer-based cartridge casing for subsonic ammunition
US9372054B2 (en) 2011-01-14 2016-06-21 Pcp Tactical, Llc Narrowing high strength polymer-based cartridge casing for blank and subsonic ammunition
US10794671B2 (en) 2011-01-14 2020-10-06 Pcp Tactical, Llc Polymer-based cartridge casing for subsonic ammunition
US9995561B2 (en) 2011-01-14 2018-06-12 Pcp Tactical, Llc Narrowing high strength polymer-based cartridge for blank and subsonic ammunition
US8869702B2 (en) * 2011-01-14 2014-10-28 Pcp Tactical, Llc Variable inside shoulder polymer cartridge
US9003973B1 (en) 2011-01-14 2015-04-14 Pcp Tactical, Llc Narrowing high strength polymer-based cartridge casing for blank and subsonic ammunition
US9395165B2 (en) 2011-07-28 2016-07-19 Mac, Llc Subsonic ammunition casing
US9335137B2 (en) 2011-07-28 2016-05-10 Mac, Llc Polymeric ammunition casing geometry
USD765214S1 (en) 2012-01-13 2016-08-30 Pcp Tactical, Llc Radiused insert
USD715888S1 (en) 2012-01-13 2014-10-21 Pcp Tactical, Llc Radiused insert
US9528799B2 (en) 2014-01-13 2016-12-27 Mac Llc Neck polymeric ammunition casing geometry
US9453714B2 (en) 2014-04-04 2016-09-27 Mac, Llc Method for producing subsonic ammunition casing
WO2015154079A1 (en) * 2014-04-04 2015-10-08 Mac, Llc Method for producing subsonic ammunition casing
USD813975S1 (en) * 2015-08-05 2018-03-27 Mark White Low volume subsonic bullet cartridge case
US11913764B2 (en) 2017-04-19 2024-02-27 Pcp Tactical, Llc Cartridge case having a neck with increased thickness
US11448491B2 (en) 2018-07-30 2022-09-20 Pcp Tactical, Llc Polymer cartridge with enhanced snapfit metal insert and thickness ratios

Also Published As

Publication number Publication date
DE2136750C3 (de) 1974-03-21
DE2136750A1 (de) 1972-05-25
DE2136750B2 (de) 1973-08-09
BE770369A (fr) 1971-12-01
SE387434B (sv) 1976-09-06
JPS4943437B1 (de) 1974-11-21
GB1346828A (en) 1974-02-13
FR2103794A5 (de) 1972-04-14

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