JP7504260B2 - Ammunition container - Google Patents

Description

The present invention relates to a cylindrical ammunition container used as a packaging container for howitzer propellants and artillery ammunition.

As described in the following Patent Document 1, an ammunition container used for howitzer propellants and the like is a metal container that is temporarily used when packaging, transporting, and storing in an ammunition depot multiple propellants loaded with fine granular propellants. When inserting the propellant charge into the chamber of a howitzer or the like, the ammunition container is removed from the propellant charge. In general, ammunition containers used as packaging containers for howitzer propellant charges and artillery ammunition are structured to have a certain level of drop strength and airtightness in consideration of operational aspects.

In recent years, in order to minimize damage to the user when a fire or bullet strikes during storage, transportation, or use, ammunition for howitzers and other artillery ammunition is damaged, development and installation of insensitive or low-sensitivity ammunition (hereinafter referred to as IM (Insensitive Munition)) has been promoted. In addition, test methods for evaluating the IM properties and handling of these ammunition have been standardized in the United States' ITOP (International Test Operations Procedure) and STANAG (Standardization Agreement, NATO standard). Test items for evaluating operational handling in these standards include drop tests, cook-off tests, sympathetic detonation tests, gunfire sensitivity tests, and fragmentation impact tests. These regulations must be satisfied not only for the ammunition itself but also for the ammunition container, so high IM properties, strong drop strength, and high airtightness are required for howitzer launch charges and artillery ammunition containers.

The following Patent Document 2 discloses a cylindrical ammunition container made of metal with a spiral joint, with the aim of providing a cylindrical ammunition container that can mitigate the combustion reaction of ammunition while maintaining its strength. The cylindrical ammunition container is characterized in that a cut is provided on at least one of the outer and inner surfaces of the cylinder in a position that does not interfere with the joint, and the ratio of the depth of the cut to the wall thickness of the cylinder is 0.10 to 0.95.

The following Patent Document 3 also discloses an ammunition storage container that opens when it receives an undesirable stimulus that causes the ammunition to burn, the container having a top, a bottom, and at least one side therebetween, where the container stores an explosive therein, the explosive including an energetic material, and has at least one seam on the side having a bonded portion and a non-bonded portion; and a seal made of adhesive or the like for sealing the non-bonded portion of the seam, where the seal acts to break when the internal pressure is at least 3 psi higher than the external pressure before the remainder of the container breaks; thereby opening the container and controlling the burning rate of the stored energetic material to avoid violent reactions.

The following Patent Document 4 discloses an ammunition container that has a cylindrical container body with a bottom and a lid that covers the opening of the container body, with the aim of providing an ammunition container that maintains drop strength and airtightness under normal conditions, but can avoid the container exploding in an emergency when explosives ignite inside the container and limit damage to the surrounding area. The tubular part of the container body is formed into a cylindrical shape with a joint that extends in a spiral shape by spirally winding a metal elongated plate and joining both side edges of the plate, and the tubular part has a through hole that extends in the axial direction and penetrates from the inside to the outside, the through hole is sealed with a sealing material, and the through hole and the outer surface of the sealing material are covered with a metal cover member.

The following Patent Document 5 discloses an ammunition container that has a cylindrical container body with a bottom and a lid that covers the opening of the container body, with the aim of providing an ammunition container that maintains drop strength and airtightness under normal conditions, but can avoid the container exploding in an emergency when explosives ignite inside the container and limit damage to the surrounding area, and is characterized in that through holes of a predetermined shape and length are drilled through the inside and outside of the cylindrical part of the container body with a predetermined gap, the through holes are arranged alternately with joints of a predetermined length and extend in the axial direction as at least one stitch-like weak part, and the container is sealed by providing a sealing means in the gaps of all the through holes in the stitch-like weak part extending in the axial direction.

As mentioned above, Patent Documents 2, 3, 4, and 5 propose providing sealing materials to weak parts and openings of various shapes in a metal cylinder as conventional technology.

JP 2004-226031 A JP 2011-145007 A U.S. Pat. No. 7,624,888 JP 2013-44454 A JP 2015-227764 A

As described above, in conventional metal ammunition containers, if the explosives that make up the ammunition or propellant charge contained inside the container are partially detonated or explode due to being hit by a bullet or bullet fragments, the cylindrical body of the container will shatter into pieces before the shock waves cause the vulnerable part described above to open and release the combustion gas, or before the lid opens and releases the combustion gas, causing a situation that causes great damage and loss to surrounding personnel and equipment. To solve this problem, it would be necessary to increase the thickness of the cylindrical body of the container by approximately three times, regardless of the lid structure, but this would make the container body heavy, making it difficult to transport by hand and impractical.

If a lightweight material that does not contain fibers or has short fibers with random fiber orientation is selected in order to reduce weight, the container body may be destroyed unevenly, and various pieces of different sizes may fly off and affect the surrounding area.
Furthermore, if the material of the container body is made of fiber-reinforced resin that is strong in the circumferential direction of the cylinder, when the explosives partially detonate or explode, the container body may break into two and scatter like a rocket, or the lid or bottom may scatter, similarly affecting the surrounding area.

In addition, if the explosives contained in the container are placed in a high-temperature environment and ignite, the combustion gases generated by the burning of the explosives will cause the pressure inside the container to rise suddenly, causing the container to explode and affecting the surrounding area.
Furthermore, the above patent documents do not disclose or teach the relationship between the fiber direction and strength of the fiber-reinforced composite material, the method of installing at least one weak portion, or the provision of a sealing means for closing the weak portion.

The object of the present invention is therefore to provide an ammunition container that has high airtightness and operability, and can reduce damage to the surrounding area when explosives explode, etc.

The inventors conducted extensive research and experiments using various metals and resins in order to solve the above problems, and as a result, they confirmed that by making the cylindrical portion of the container body out of a fiber reinforced resin material (fiber reinforced plastic) that is strong in the axial direction and prone to cracking in the circumferential direction, and by providing an optimal container body structure or a weak portion in the container body so that the container body will begin to break at a specified pressure, and optionally providing a sealant in the gaps in the weak portion, if the explosives contained in the container partially detonate or explode due to being hit by a bullet or bullet fragments, etc., the container body will be prone to crack in the circumferential direction, and because it is strong in the axial direction, the resin impregnated with the fibers will break as it is crushed, thereby ensuring that the scattered debris will be lightweight.
In addition, it was confirmed that in the event that the internal explosives are placed in a high-temperature environment and ignite, the vulnerable parts can be quickly broken, more reliably releasing the combustion gases and ensuring the safety of the surrounding area.
It was confirmed that by maintaining the airtightness of the container, the ammunition contained therein can be stored for long periods of time in the container.
Furthermore, it was confirmed with the container body that by being able to select a material that is stronger and lighter than metal or resin alone, practical usability during transportation can be improved, which led to the completion of the present invention.

That is, the present invention is as follows.
[1] An ammunition container having a container body having a cylindrical portion and a bottom portion closing one of both ends of the cylindrical portion, and a lid body closing the other opening of both ends of the cylindrical portion,
The cylindrical portion includes a fiber-reinforced plastic, and the limit static internal pressure of the cylindrical portion is 0.2 to 2.0 MPa;
The tubular portion includes at least one weakened portion,
The fibers of the fiber-reinforced plastic are arranged by a filament winding method, and
The ratio of the tensile strength in the circumferential direction to the axial direction of the cylindrical portion is 2 to 250%.
An ammunition container comprising:
[2] The ammunition container described in [1], wherein the fragile portion is sealed with a sealant.
[3] The ammunition container according to [1] or [2], wherein the fragile portion has a linear structure, a groove structure, a thin-walled structure, a portion not containing fibers, or a combination thereof.
[4] An ammunition container according to any one of [1] to [3], wherein the fiber of the fiber-reinforced plastic includes at least one selected from the group consisting of glass fiber, metal fiber, pulp fiber, ceramic fiber, resin fiber, carbon fiber, and wood fiber.
[5] The ammunition container according to any one of [1] to [4], wherein the plastic of the fiber-reinforced plastic comprises at least one selected from the group consisting of epoxy resin, polyacetal resin, vinyl chloride, unsaturated polyester resin, acrylic resin, polycarbonate resin, and phenol resin.
[6] the steps of:
forming a plastic tube having reinforcing fibers disposed therein by a filament winding process;
forming at least one weakened portion in the obtained tubular portion; and
a step of closing one of both ends of the obtained cylindrical portion with a bottom portion and closing the other opening with a lid;
1. A method of making an ammunition container comprising:
A method for manufacturing an ammunition container, characterized in that the resulting cylindrical portion has a limit static internal pressure of 0.2 to 2.0 MPa and a ratio of the tensile strength in the circumferential direction to the axial direction of the cylindrical portion is 2 to 250%.

The present invention provides an ammunition container that has high airtightness and operability, and can reduce damage to the surrounding area when explosives explode.

FIG. 2 is a perspective view of an ammunition container having a plurality of linear weakened portions according to the present embodiment. FIG. 2 is a perspective view of an ammunition container according to the present embodiment. 4A to 4C are diagrams illustrating various structures of the fragile portion. FIG. 2 is a diagram illustrating an example of a method for manufacturing a cylindrical portion. FIG. 2 is a diagram illustrating an example of a method for manufacturing a cylindrical portion. FIG. 2 is a diagram illustrating an example of a method for manufacturing a cylindrical portion. FIG. 1 is a schematic diagram illustrating various safety evaluations. FIG. 1 is a diagram illustrating the setup state of safety test 1. FIG. 2 is a diagram illustrating an example of a method for manufacturing a cylindrical portion. FIG. 1 is a diagram illustrating an example of a safety test result in each embodiment. FIG. 1 is a perspective view of a prior art ammunition container. FIG. 1 is a perspective view of a prior art ammunition container.

Hereinafter, an embodiment of the present invention will be described in detail.
1 and 2 are perspective views showing an example of the configuration of an ammunition container according to the present embodiment. Also, Fig. 3 shown later is a view showing various structures of fragile parts of the ammunition container according to the present embodiment.

The inventor analyzed the destruction mode of the container according to the reaction mode of the explosives placed inside the container, produced test specimens with different rigidity and physical properties, and further verified them. As a result, it was found that with the weak parts and thickness of the container of the conventional technology, when the explosives partially detonate or detonate, they cannot withstand the shock waves generated, causing the container to fragment and making it impossible to ensure safety, or that if the rigidity of the container is pursued to withstand the shock waves, the container becomes heavy, for example, by 10 kg or more, and the operability of the ammunition container, which is often transported by hand, cannot be maintained. Therefore, instead of the conventional container structure, the material of the container body, for example the cylindrical part, is made of fiber-reinforced resin, and the directionality of the fibers and the shape of the linear weak parts were examined, and it was confirmed that the weight of the entire ammunition container can be reduced compared to the conventional method by using a combination of lightweight materials while ensuring the safety of the surroundings, and therefore transportability can be maintained or improved.

That is, in FIG. 1 showing one embodiment of the present invention, an ammunition container 1 is an ammunition container having a container body 4 having a cylindrical portion 2 and a bottom portion 3 closing one of both ends of the cylindrical portion, and a lid body 5 closing the opening of the other of both ends of the cylindrical portion 2, characterized in that the cylindrical portion 2 contains fiber reinforced plastic and has a limit static internal pressure of 0.2 to 2.0 MPa.
In the ammunition container of the present invention, the cylindrical portion contains fiber-reinforced plastic, and the limiting static internal pressure of the cylindrical portion (the static internal pressure at which it breaks and opens) is within the above-mentioned range, and therefore the ammunition container is superior to conventional metal ammunition containers having fragile portions and ammunition containers made solely of fiber-reinforced plastic in the following respects:

In other words, the ammunition container of the present invention maintains drop strength, airtightness, and operability under normal circumstances, but in the event of an emergency in which explosives partially detonate inside the container, the fibers contained in the tube reduce the weight of the flying fragments of the tube, thereby suppressing the impact on the surrounding area. Also, when explosives detonate inside the container, by arranging the direction of the fibers contained in the tube close to the axial direction of the tube, the tube of the container body will first crack in the circumferential direction, mitigating the impact, and preventing the lid and bottom from splitting into two and flying off.

This makes it possible to more reliably suppress the impact on the surrounding area, and in the event of an emergency such as an ignition of explosives inside the container, the explosion pressure can be reduced by quickly securing an opening in the axial direction of the tube or through the linear weak part, and the ability to select a material that is lighter than metal increases practical usability.
If the limit static internal pressure of the cylinder is too low, the operability, airtightness, etc. will decrease. On the other hand, if it is too high, the energy of the explosion will be accumulated, generating shock waves and causing fragments to fly. By keeping the limit static internal pressure within the above range, it is possible to suppress the scattering of fragments at the time of explosion and reduce damage to the surrounding area while maintaining operability and airtightness.

In this way, in the ammunition container of the present invention, the type of fiber and resin in the container body, the fiber direction (braiding angle), the amount of fiber, and the strength and shape of the linear weak part can be changed depending on the composition and shape of the explosives contained inside, the reaction form, the shape and mass of the ammunition container, and the operation method, thereby maintaining airtightness and drop strength during normal handling and reliably reducing the mass of flying fragments in the event of an abnormality.

The ammunition container of the present invention satisfies the following requirements: (1) the cylindrical portion contains fiber-reinforced plastic, and the limiting static internal pressure is regulated; (2) the cylindrical portion has a weak portion; and (3) the axial and circumferential tensile strength ratio is regulated. This allows the container to achieve a particularly high drop strength while adjusting separation and drop strength. This high drop strength cannot be achieved by the weak portion alone or the tensile strength ratio alone, but can only be achieved by combining (1) to (3).

Fig. 11 shows a conventional ammunition container. In the figure, the gap of the through hole of the weak part of the container body is shown. In the figure, A: length of the weak part, B: gap of the through hole, C: length per through hole, D: joint length between the through holes, E: container body, F: lid.
The lid is screw-type, and a linear through hole constitutes a slit in the container body, and the through hole has a predetermined gap.

The gap of the through hole in the present invention is defined in the same way as that shown in FIG. 11, but is defined as B in FIG. 2. The ammunition container (also simply called the container) has a container body having a cylindrical portion and a bottom portion that closes one of the ends of the cylindrical portion, and a lid that closes the opening of the other of the ends of the cylindrical portion, and is designed to load multiple ammunition (not shown) in series inside. As ammunition, explosives such as single base propellant, double base propellant, triple base propellant, multi-base propellant, propellant, explosive, and explosive are used.

<Container body>
The container body 4 according to this embodiment has a cylindrical portion 2 and a bottom portion 3 that closes one of both ends of the cylindrical portion 2 .
The shape of the container body may be any shape, from polygonal to circular or elliptical, but a cylindrical shape with high mechanical strength (second moment of area) is even more usable because it can be made thin and lightweight.

The length of the cylindrical portion may be 10 mm or more, 100 mm or more, or 1000 mm or more, and it is desirable to set it appropriately taking into consideration the amount of explosive to be contained, the storage space, and the shape.
The thickness of the cylindrical portion may be 0.6 mm or more, 1.0 mm or more, or 2 mm or more, and is desirably set appropriately so as not to be deformed during handling.
The inner diameter of the cylindrical portion may be 4 mm or more, 10 mm or more, or 160 mm or more, and can be appropriately set depending on the size of the contents, the purpose, and the usage environment. For example, when the length or diameter of the cylindrical portion is small, such as 4 to 5 mm, the static internal pressure (MPa) strength at which the container body breaks can be ensured even if the thickness of the cylindrical portion is thinned. Conversely, when the length of the cylindrical portion is large, such as 10 m or the width (diameter, etc.) is large, such as 1 m, it is necessary to increase the thickness of the cylindrical portion and increase the strength of the fragile portion and the tensile strength of the container body in order to maintain the static internal pressure (MPa) strength at which the container body breaks.

For example, the formula for calculating the static internal pressure (MPa) at which the cylinder breaks (limit static internal pressure) is "2 x thickness of the cylindrical container body (mm) x circumferential tensile strength of the cylinder (MPa) ÷ inner diameter of the cylinder (mm)" or "2 x thickness of the cylindrical container body mm x circumferential tensile strength of the cylinder with the fragile part (MPa) ÷ inner diameter of the cylinder (mm)". The thickness and structure of the container are designed by adding a safety factor and processing tolerance according to the application to the above formula. Similarly, when the container body is a container shape other than a cylinder, the static internal pressure at which the container body breaks is appropriately calculated, and the thickness and structure of the container are designed. In general, the effect of this embodiment can be predicted by calculating the static internal pressure (MPa) at which part of the container body breaks.

The barrel of the ammunition container of the present invention contains fiber-reinforced plastic, which makes it lighter than a metal barrel and improves operability.
In ammunition containers of the present invention, the base and/or lid may also optionally comprise fiber reinforced plastic.

There are no particular limitations on the fibers of the fiber-reinforced plastic, and any fibers that can adhere to the resin impregnated or applied to the fibers can be used, in order to ensure the tensile strength required to break the resin while pulverizing it in the event of an abnormal reaction of explosives, and to ensure airtightness under normal conditions.
Such fibers preferably include at least one selected from the group consisting of glass fibers, metal fibers, pulp fibers, ceramic fibers, resin fibers, carbon fibers, and wood fibers.

The plastic used for the fiber reinforced plastic is not particularly limited, and any plastic can be used as long as it is capable of being impregnated or coated on the fibers and adhered thereto in order to ensure airtightness under normal circumstances while being crushed by the fibers in the event of an abnormal reaction of explosives.
Such plastics preferably include at least one selected from the group consisting of epoxy resin, POM (polyacetal) resin, vinyl chloride, unsaturated polyester resin, acrylic resin, polycarbonate resin, and phenol resin.

In the ammunition container of the present invention, the ratio of the tensile strength in the circumferential direction of the tube to the axial direction of the tube (circumferential direction/axial direction) may be 2% or more, 3% or more, 5% or more, 8% or more, 10% or more, 15% or more, 20% or more, or 27% or more, and may be 250% or less, 242% or less, 240% or less, 230% or less, 200% or less, 199% or less, 150% or less, or 100% or less. In particular, this ratio is preferably 2 to 250%, and more preferably 3 to 100%. The tensile strength ratio for the tube is a value for the tube alone without a weak portion.
If the tensile strength ratio is too small, the container will be easily deformed, and if it is too large, it will separate during an explosion and fly apart like a rocket. By setting the tensile strength ratio within the above range, the separation of the container can be adjusted.

In particular, by setting the tensile strength ratio at 3-100%, it becomes easier to adjust the separation of the containers. In other words, by strengthening the axial strength, it becomes possible to adjust the proportion of the axial joint to a larger extent, ensuring airtightness and reducing damage to the surrounding area when explosives explode, etc.

The axial tensile strength is determined by cutting a sample (plate-shaped test piece) as described in JIS K 7033 (Method C) from the cylinder and conducting a tensile test at a speed of 5±1 mm/min in an environment of 23°C±2°C and relative humidity of 50%. The circumferential tensile strength is determined by cutting a sample (plate-shaped test piece) as described in JIS K 7037 (Method C) from the cylinder and conducting a tensile test in the same manner as above.

The tensile strength of the fragile part described later can be obtained by setting the sample so that it breaks from the fragile part and dividing the breaking load N at that time by the area ( ^mm2 ) of the part where the fragile part is not provided. In general, when the cylinder of the container body is manufactured by the filament winding method and the braiding angle is 25.8 degrees, the ratio [%] of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder is approximately 9% (approximately 30/340 MPa), when the braiding angle is 54.7 degrees, it is approximately 370% (approximately 185/50 MPa), and when the manufacturing method using prepreg is used and the braiding angle is 0 degrees, the ratio of the tensile strength in the axial direction to the circumferential direction is approximately 2% (approximately 30/1600 MPa). In addition, when the braiding angle of the cylinder of the container body is changed for each winding layer, the tensile strength in the circumferential direction of the cylinder is proportional to the sum of the tensile strengths of each layer. Furthermore, when the braiding angle is changed for each winding layer to provide a weakened portion in the cylinder, the sum of the breaking loads for each layer in the joined portion is proportional to the breaking load in the circumferential direction of the cylinder.
By increasing the strength in the axial direction of the cylinder and weakening the strength in the circumferential direction by changing the fiber weave angle, the direction and amount of fiber in each layer, or the type and thickness of fiber, or by arranging the fibers or weak parts, or both, it is possible to more reliably prevent the container from breaking into two and shattering due to an increase in internal pressure, and reduce damage to the surrounding area.

The cylindrical portion of the container body may be made of fibers having a fiber length of 10 mm or more, preferably 24 mm or more, mixed with resin (Fig. 4 (1)), or made of the same fibers as above mixed with resin and formed into a sheet (Fig. 4 (2)). In this case, the fiber direction is random, and the ratio of the tensile strength in the circumferential direction of the cylindrical portion to the axial direction of the cylindrical portion is approximately 100% (approximately 150/150 MPa), but in the event of an emergency in which the explosives inside the container partially detonate, the fibers contained in the cylindrical portion will cause the cylindrical portion to break into pieces, reducing the weight, so this may be used.

For example, as shown in Figure 5, when the direction of the fibers contained in the cylindrical container body is set at 45 degrees using the filament winding method, the ratio of tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder is approximately 100% (approximately 150/150 MPa).

Fibers arranged by the filament winding method are wound in one layer at 30 degrees to the axial direction of the cylindrical container body, and then in the next layer, they are wound at 150 degrees to the same axial direction of the cylindrical container body, so that the fiber direction is the same 30 degrees to the axial direction of the cylindrical container body. In other words, 100% of the fibers are arranged by the filament winding method at 30 degrees to the axial direction of the cylindrical container body. At this time, the axial tensile strength of the cylinder is approximately 300 MPa, while the circumferential tensile strength of the cylinder is approximately 54 MPa, and the ratio is approximately 18%. Alternatively, the winding angle (braiding angle) can be changed for each winding layer, or reinforcing fibers can be added in any direction to change the strength in the axial and circumferential directions of the cylinder.

In contrast, as shown in Figure 6, if a sheet (such as a prepreg) made of cloth or fabric with warp and weft threads soaked in resin is wound into a roll to produce a pipe, the ratio of the tensile strength in the axial direction of the cylinder of the container body to the circumferential direction of the cylinder can be set as desired by changing the prepreg or lamination method to change the strength and amount of the warp and weft threads as desired.

<Lid>
The cover 5 closes the other opening of the cylindrical portion 2 in the container body 4 .
The material and shape of the lid are not particularly limited as long as it can seal the inside of the ammunition container. For example, in addition to metal, it can be made of plastic, fiber-reinforced plastic, paper, resin-impregnated paper, or rubber. However, in order to prevent the lid from scattering before the container body is destroyed, it is desirable that the bonding strength between the lid and the container body is higher than the impact or pressure applied to the lid from the inside. If the strength of the lid cannot be ensured, a mechanism may be provided in which a fragile part or the like is provided in the lid to release pressure and prevent the lid from scattering. Chain fibers may be used because they break down the fragments of the tube and reduce the weight.

If the lid is attached to the above-mentioned tubular part of the main body with sufficient strength (screw structure, etc.), it can prevent the lid from flying off regardless of whether the lid is made of metal, resin, composite material, or has a weak part. The adhesive strength of the lid can be selected according to the normal handling strength and internal pressure during abnormal conditions.

<Weakened Parts>
The ammunition container 1 according to this embodiment preferably has at least one fragile part 10 in the cylindrical part 2. By having the fragile part 10 in the cylindrical part 2, the ammunition container 1 can adjust the time in seconds at which the pressure release of the combustion gas starts.

The fragile portion preferably has a linear structure, a groove structure, a thin-walled structure, a portion not containing fibers, or a structure of a combination of these.
It is preferable that at least one weakened portion is provided in the axial direction or the helical direction of the cylindrical portion.

The length of the fragile portion, for example a fragile portion having a linear structure, may be at least 10%, at least 50%, or at least 80% of the length of the cylindrical portion, and it is desirable to set the length appropriately in accordance with the combustion performance of the explosive to be placed inside and the maintenance of the shape of the container.
The length of each weakened portion may be 1 mm or less, 90 mm or less, or 800 mm or less, and is desirably set appropriately in accordance with the material so that the shape can be maintained during handling.
The width of the weakened portion may be 0.1 mm or more, 2.0 mm or more, or 5.0 mm or more, and it is desirable to appropriately set the width so that the weakened portion can be processed.

The number of fragile parts perforations in the cylindrical part of the container body may be one, but as long as the container strength is maintained, multiple parts (e.g., 2 to 15 parts) may be provided as shown in Figure 1. The length of the fragile part may be set appropriately according to the number of perforations. For example, if the number of perforations in the fragile part is relatively small (e.g., 1 to 3 parts), the fragile part may be long, and if the number of perforations in the fragile part is relatively large (e.g., 4 or more parts), the fragile part may be short. In addition, if multiple fragile parts are provided, it is preferable to provide them at equal intervals in the axial direction of the container body. This is because it is easier to form opening holes and allows the combustion gas to be released efficiently to the outside.

The fragile portion is basically linear or broken, preferably linear, but depending on the shape of the container and the explosives contained therein, it can be curved or spiral, or have Y- or H-shaped notches at both ends to facilitate the release of pressure. The fragile portion may be provided parallel to the axial direction (central axis) of the container body, or obliquely (spiral) relative to the axial direction (central axis) of the container body, or the fragile portion can be provided perpendicular to the axial direction of the container body. Of these, it is preferable to provide the fragile portion parallel to the axial direction (central axis) of the container body or obliquely (spiral) relative to the axial direction (central axis) of the container body, since this reduces the possibility of the container body being divided and the explosives remaining inside being burned and scattered like a rocket.

In this embodiment, as shown in Figures 1 and 2, one or two long, dashed, straight through holes are formed in the tubular portion as fragile portions, extending to both axial ends of the container body and parallel to the axial direction (center axis) of the container body. The length of at least one of the fragile portions is 0.2 or more, preferably 0.5 or more, and may be 0.8 or less, 0.6 or less, relative to the length of the tubular portion, allowing efficient release of combustion gas to the outside upon ignition.

As shown in Figure 12, in the cylindrical part of the container body of the conventional technology, a weak part extending in the axial direction is drilled so that the through hole and the joint are linear, and the through hole is drilled so as to penetrate from the inside to the outside. It has been believed that by having this weak part, when ammunition ignites inside the ammunition container, the weak part opens and releases combustion gas from inside the ammunition container, suppressing the rise in internal pressure and preventing the ammunition container from bursting.

However, as mentioned above, the inventor analyzed the destruction mode of the container according to the reaction mode of the explosives placed inside the container, produced test specimens with different rigidity and physical properties, and further verified them. As a result, he found that with the slit structure of the conventional technology, when the explosives placed inside cause a detonation reaction and shock waves are generated, the container breaks into fragments before the weak part opens, affecting the surrounding area, and that if the rigidity (thickness) of the container is increased to withstand the shock waves, the weight of the entire ammunition container becomes heavy and portability is impaired. Therefore, he newly provides a modified weak part installation that matches the structure of the fiber-reinforced resin material of the tube.

Figure 3 shows an example of the structure of the weak part of the ammunition container according to this embodiment. When the weak part is a through hole as shown in Figure 3 (1), the strength of the weak part is proportional to the ratio of the length of the through hole to the length of the joint as shown in Figure 2 multiplied by the tensile strength of the base material.

When the fragile part is grooved (thin) as shown in Figure 3 (2) or laminated to a thin structure as shown in Figure 3 (3), the strength of the fragile part is proportional to the ratio of the tensile strength before processing to the tensile strength of the non-penetrating part after groove processing. When the fragile part is a non-penetrating hole with the fibers broken and the tensile strength weakened in some parts as shown in Figure 3 (4), the strength of the fragile part is proportional to the ratio of the tensile (bonding) strength of the fragile part to the non-fragile part. When the cylinder is made into a square cylinder (polygon) as shown in Figure 3 (5), the corners of the container body have the strength of the fragile part where stress is concentrated when internal pressure is generated.

<Sealing material>
In the ammunition container, the fragile portion is preferably sealed with a sealant.
In some cases, a plate-shaped sealant is attached to the outer periphery of the cylindrical part of the ammunition container of the prior art so as to seal the through hole from the outside. The sealant is typically larger than the opening area of the through hole, and is attached to the container body at the outer periphery of the through hole by adhesion, welding, or the like. The sealant is typically made of a material having a lower tensile strength than the container body. This is because when ammunition ignites inside the ammunition container, the sealant must be broken preferentially over other parts as the internal pressure rises. In other words, the through hole and the sealant are included in the fragile part.

In contrast, in the fiber-reinforced resin ammunition container according to this embodiment, the gap in the through hole may be filled with a sealant to seal the container, as shown in FIG. 3 (6). The fragile portion may be grooved as shown in FIG. 3, and the container may be sealed by joining the grooves. Furthermore, the container may be sealed by applying a sealant to the groove. Alternatively, a portion that is not fiber-reinforced may be provided to serve as the fragile portion.

The material of the sealant to keep the weak part airtight may be a metal such as aluminum or copper, or a synthetic resin such as a filler, paint, adhesive, or caulking agent, or a composite material such as FRP, and the container may be sealed using this. Also, as shown in FIG. 3 (7), the container may be sealed by covering the through hole with the above sealant in the form of a tape or plate.

When using a sealant such as a tape that is vulnerable to external impacts, it is preferable to provide a mechanism for protecting the sealant depending on the method of use. For example, as shown in Fig. 3 (8), a protective plate may be further provided on the tape.
Alternatively, the container may be sealed at a joint or weld where the fibers are interrupted and not reinforced with fibers.

When a sealant is used, the material is preferably an adhesive or filler that decomposes and burns when exposed to heat, and most preferably a paint. When the combustion gas causes a rise in pressure inside the container, the sealant is destroyed by the combustion gas (heat), opening the weak parts and making it easier for the combustion gas to be released.

The operation of the fiber-reinforced resin ammunition container according to this embodiment will be described below.
The ammunition container 1 according to one embodiment of the present invention shown in FIG. 1 is characterized in that the container body 4 or a fragile portion 10 provided on the container body 4 breaks at a static internal pressure of 0.2 to 2.0 MPa, creating an opening.

When the ammunition container is transported or temporarily stored, if the ammunition in the ammunition container undergoes a combustion reaction due to an impact or temperature rise, the pressure inside the ammunition container will rise due to the combustion gases generated. Next, the container body or a weak part provided in the container body will begin to break due to the combustion gases at 0.2 MPa or more, preferably 0.4 MPa or more, more preferably 0.6 MPa or more, and 2.0 MPa or less, preferably 1.5 MPa or less, more preferably 1.0 MPa or less. If a weak part is provided, an opening of a specified size will be created in the direction of the weak part or in the direction of the weak strength, and the combustion gas will be released to the outside at or below the safe internal pressure of the container.

If the static internal pressure at which it breaks is less than 0.2 MPa, the drop strength will be insufficient, it will lose its airtightness, and normal handling will be impossible. This will prevent the internal pressure of the ammunition container from increasing, which will prevent the container from exploding, i.e., scattering of fragments, and increase safety. Conversely, if it exceeds 2.0 MPa, energy will be accumulated and shock waves will be generated, exceeding the pressure resistance of the container, causing it to break from any point, generating fragments and blast waves, and fragments will scatter. This increases the possibility of affecting the surrounding area. By keeping the static internal pressure at which it breaks and opens within the above range, it is possible to maintain operability and airtightness while suppressing scattering of fragments in the event of an explosion, thereby reducing damage to the surrounding area.

In addition to the above, if a metal fragment traveling faster than a certain speed penetrates an ammunition container, the ammunition inside the container will partially detonate, generating a shock wave that will cause a sudden rise in pressure and fragment the container, regardless of whether or not there is a weakened portion in the container or lid.
In this case, if the tube is made of fiber-reinforced resin, the fibers will crush the resin, making the flying fragments lighter, or no fragments will be generated, minimizing the impact on the surroundings. Also, if the direction of the fibers is arranged at an angle close to the axis of the tube, even if a larger shock wave occurs, the container body will be divided into two and prevented from flying off like a rocket, increasing safety for the surroundings.

In addition, if the lid is joined to the above-mentioned tubular portion of the main body with sufficient strength (e.g., a screw structure), it is possible to prevent the lid from scattering regardless of whether the lid is made of metal, resin, composite material, or has a weak portion. The adhesive strength of the lid can be selected according to normal handling strength and internal pressure in the event of an abnormality.

Furthermore, in the case of conventional ammunition containers, if the ammunition contained therein undergoes an explosive reaction, the scattering fragments can be suppressed by increasing the thickness of the metal container by several times, for example by approximately three times, but this makes the container heavy and makes it difficult to transport.
In contrast, the ammunition container according to this embodiment, which uses lightweight materials such as fiber and resin, prevents the container from becoming heavy and maintains portability.

The present invention will be specifically explained with reference to the following examples.

The evaluation methods used in the examples are described below.

[Portability evaluation]
If the bag contains ammunition or other contents, it will become heavy, so the total weight will be important in the event of an emergency.
This time, the weight of only the 1100 mm long ammunition container, without any contents such as ammunition, was evaluated.
The evaluation was performed with the cylindrical portion made of resin or a composite material, and the lid and bottom made of metal.
◎: Lighter than the existing imitation (made of metal) (10.9 kg or less)
○: Approximately the same weight as the existing imitation (made of metal) (approximately 11.0 kg)
×: Heavier than the existing imitation (made of metal) (11.5 kg or more)

(Safety evaluation test procedures)
The safety evaluation tests included two evaluations: Safety 1 (fragment impact test) and Safety 2 (slow cook-off test). However, if some of the evaluations were not cleared, the other evaluations were omitted.

[Safety 1 Evaluation]
In the evaluation of Safety 1, a fragment impact test was used, which is an evaluation of reactivity when a high-temperature metal piece hits a charge, as shown in FIG.
Measures the number of fragments that break apart when a container explodes due to an external impact. Damage (impact) from weak parts is virtually irrelevant, and measures the scattering of fragments throughout the container. If destruction occurs from a part other than the slit, the fibers cause the container to break into small fragments, making it safe. If the fibers are small, the container will be similar to one without long fibers.

As shown in Figure 8, a test was conducted to collide a specified metal fragment with an ammunition container containing a propellant charge at a speed of 1,830 m/s and confirm the reaction at that time. Such fragment impact tests and evaluations were conducted under conditions compliant with STANAG.

(Evaluation of Safety 1)
Among the fragments weighing more than 150g, the number of fragments that flew 15m or more and the state of fragmentation of the container body were used to evaluate safety according to the following criteria.
◯: 0 fragments of 150 g or more that were scattered over 15 m or more. ×: 1 or more fragments of 150 g or more that were scattered over 15 m or more were generated.
An example of the results of the fragment impact test is shown in FIG.

[Safety 2 Evaluation]
In the evaluation of Safety 2, a slow cook-off test was used, which is an evaluation of reactivity when the charge is held at a high temperature, as shown in FIG.
Evaluates how a container breaks down due to an internal explosion. The number of fragments generated when a container explodes from the inside is measured. This test is based on the assumption of a fire, etc., and breakage occurs from specific parts such as weak parts, and an explosion will occur if there are no weak parts.

As shown in Figure 7, a test was conducted to confirm the reaction state by wrapping an ammunition container containing a propellant charge in a ribbon heater and then wrapping it in insulating material, and raising the temperature at a rate of 3.3 degrees per hour until the explosives inside ignite. The slow cook-off test and evaluation were conducted under conditions compliant with STANAG.

(Evaluation of Safety 2)
Among the fragments weighing more than 150g, the number of fragments that flew 15m or more and the state of fragmentation of the container body were used to evaluate safety according to the following criteria.
＜Overall＞
○: 0 fragments of 150g or more scattered over 15m ×: 1 or more fragments of 150g or more scattered over 15m <Breakdown state of container body>
◯: The container body cracked along the fragile portion, and the container remained in place.
×: The container body cracks in the circumferential direction, and the container is divided into two and scattered.

[Evaluation of container drop strength]
(Drop test)
A test was conducted in which a package containing contents was allowed to fall naturally from a specified height. Specifically, a propellant charge was placed in the package, and the package was set to a specified height (12 m, 2.1 m, 1.5 m) and a specified angle (horizontal, vertical, diagonal) according to I-TOP. The ground on which the package fell was concrete with a 20 mm thick iron plate laid on it, and the package was allowed to fall naturally, and the situation after the fall was judged. For example, a package with a long through hole becomes deformed, the propellant is destroyed, and the contents (gunpowder) are released from the deformed part, which causes problems in transportation. Ammunition packages must be structured to be able to safely transport the propellant under various conditions and to store it thereafter. The situation after the fall was judged using the following evaluation indexes.
The contents of the packaging container must not scatter when dropped 12m. 2. Even after a drop of 1m, the propellant charge must be removable and the gun must be able to be fired safely. Even after a drop of 1.5m, the packaging container must have a specified airtightness (no air leaks at 0.02MPa).

(Evaluation of container drop strength)
The container drop strength was evaluated according to the following criteria:
⊚: All three of the above criteria are fully satisfied. ◯: Two of the above three criteria are fully satisfied. Δ: One of the above three criteria are fully satisfied. ×: None of the above three criteria are satisfied.

[Airtightness evaluation]
(Airtightness test)
For the following sealing materials, a tube made of glass epoxy with a weak part was prepared, and the airtightness was examined in advance. The above airtightness test (no air leak at 0.02 MPa) was conducted, and it was confirmed that the material had airtightness. In addition, assuming that ammunition containers collide with each other during actual operation, one ammunition container was dropped from a height of 50 mm onto the sealing part of the ammunition container, and the same airtightness test as above was conducted to confirm that airtightness was ensured.

(Airtightness evaluation)
○: Airtight in both airtightness tests and practical airtightness tests.
△: Airtight only during airtightness test.
×: No airtightness in both the airtightness test and the practical airtightness test.

The results of the airtightness test are shown in Table 1.

[Comparative Example 1]
The material 1 of the container body was SPCC steel plate, the tube manufacturing method was a spiral as shown in Figure 11, the ratio [%] of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was 100%, a broken line-shaped weak part (A: weak part length 900 mm, B: through hole gap 0.1 mm, C: length per through hole 50 mm, D: joint length between through holes 3 mm pitch) was provided in the same direction as the axis of the cylinder on the cylindrical part of the container body and sealed with a coating agent, a triple-base propellant charge was loaded, and both ends were sealed with lids to produce an ammunition container.
The resulting container was evaluated for transportability, safety 1, safety 2, and drop strength by the above evaluation tests. Since the container mass was approximately 11 kg, the transportability was rated as ○, and the results are shown in Table 2 below. In the evaluation of safety 1, three pieces weighing 150 g or more were generated and scattered over a distance of 15 m or more, so the safety was rated as ×. The evaluation of safety 2 was ○. The drop strength was rated as ◎.
The results of the safety test in Comparative Example 1 are shown diagrammatically in FIG.

[Comparative Example 2]
The container was tested in the same manner as in Comparative Example 1, except that the direction of the weakened portion of the container in Comparative Example 1 was changed to a spiral shape. The results are shown in Table 2 below.
The results were the same as in Comparative Example 1. Since the container mass was approximately 11 kg, the transportability was rated as ○, and in the evaluation of Safety 1, three pieces weighing 150 g or more were generated and scattered over 15 m, so the safety was rated as ×. The evaluation of Safety 2 was ○. The drop strength was rated as ◎.

[Comparative Example 3]
The test was carried out in the same manner as in Comparative Example 1, except that a 5 mm layer of polyurea resin was applied to the container of Comparative Example 1 in order to reduce the penetration rate of the fragments. The results are shown in Table 2 below.
The container mass was approximately 12 kg, so the transportability was rated as x, and in the Safety 1 evaluation, four fragments weighing 150 g or more were generated and scattered over 15 m, so the safety was rated as x. Since the Safety 1 evaluation was x, the Safety 2 evaluation and the drop strength evaluation were not conducted.

[Comparative Example 4]
The container body material 1 was an SPHC steel plate (same as in Comparative Example 1), and the test was conducted in the same manner as in Comparative Example 1, except that the thickness and the pipe-making method were changed to a flat roll shape as shown in Fig. 6. The results are shown in Table 2 below.
The container mass was approximately 12 kg, so the transportability was rated as x, and in the Safety 1 evaluation, two metal fragments weighing 150 g or more were generated, so the safety was rated as x. Since the Safety 1 evaluation was x, the Safety 2 evaluation and the drop strength evaluation were not conducted.

[Comparative Example 5]
The container body material 1 was an SPHC steel plate (same as in Comparative Example 1), and the tests were conducted in the same manner as in Comparative Example 1, except that the thickness and the pipe manufacturing method were changed. The results are shown in Table 2 below.
The container's mass was approximately 14 kg, so the transportability was rated as ×. The container did not break into pieces, and the safety was rated as ○ for both safety ratings of 1 and 2. The drop strength was also rated as ⊚.
The results of the safety test in Comparative Example 5 are shown diagrammatically in FIG.

[Comparative Example 6]
The container body was evaluated in the same manner as in Comparative Example 5, except that the material 1 of the container body was polycarbonate, the thickness of the cylindrical portion was changed to 5 mm, the width of the groove in the fragile portion was changed to 2 mm, the depth of the groove was changed to 3.25 mm, and the sealant was omitted. The results are shown in Table 2 below.
The container mass was approximately 10.5 kg, so transportability was rated as excellent. When the container body was made of resin, the resin part broke with almost no deformation, generating sharp fragments of various sizes that scattered, in the evaluation of safety 1. There were five fragments weighing 150 g or more that flew over 15 m, so safety was rated as poor. Because the evaluation of safety 1 was poor, the evaluation of safety 2 and the evaluation of drop strength were not carried out.

[Comparative Example 7]
Except for replacing the material 1 of the container body with epoxy resin, evaluation was performed in the same manner as in Comparative Example 6. The results are shown in Table 2 below.
When the container was made entirely of resin, the container mass was approximately 10.5 kg, and so transportability was rated as excellent. In the safety 1 evaluation, the resin part broke into pieces with almost no deformation, the shape and size of the pieces could not be controlled, and 10 pieces weighing 150 g or more were generated and scattered over 15 m, so safety was rated as poor. Since the safety 1 evaluation was poor, safety 2 evaluation and drop strength evaluation were not conducted.

[Comparative Example 8]
The evaluation was performed in the same manner as in Comparative Example 7, except that the material 1 of the container body was cardboard, the thickness was changed to 10 mm, the width of the groove in the fragile portion was changed to 2 mm, the depth of the groove was changed to 7.5 mm, and the pipe manufacturing method was changed to that shown in Figure 9. The results are shown in Table 2 below.
The container weighed approximately 12 kg, so portability was rated as x. Safety was rated as 0 for both safety 1 and 2, as lightweight fragments of 5g to 50g were scattered. However, the drop strength was rated as 0 because there were gaps in the fiber itself and the container was not airtight.

[Comparative Example 9]
The materials of the container were glass fiber and epoxy resin, the tube was wound as shown in Fig. 5, the direction of the fibers during the winding was changed for each winding layer, the winding angle for the inner 0.5 mm was 75 degrees and for the outer 1.5 mm was 35 degrees, the thickness of the cylinder was 2 mm, the shape of the fragile part was grooved, a groove 2 mm wide and 1.5 mm deep and 900 mm long was drilled from the outside of the cylinder, the ratio of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was 89%, the static internal pressure at which the container body breaks (critical static internal pressure) was changed to about 6.5 MPa, and no sealant was used. The evaluation was performed in the same manner as in Comparative Example 8. The results are shown in Table 2 below.
The container's mass was approximately 10.1 kg, so its transportability was rated as excellent. The safety 1 rating was rated as good, but the safety 2 rating was poor because the lid broke into two pieces weighing more than 150g that flew over 15m. As the safety 2 rating was poor, no evaluation of drop strength was conducted.

[Comparative Example 10]
The evaluation was the same as in Comparative Example 9, except that the fiber braid angle was set to 35 degrees with respect to the axis of the cylinder, the ratio of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was set to 27%, the tensile strength in the circumferential direction of the base material was set to 60% of the tensile strength of the brittle portion, and the static internal pressure at which the container body breaks was changed to approximately 2.2 MPa. The results are shown in Table 2 below.
The container's mass was approximately 10.1 kg, so its transportability was rated as excellent. In the safety 1 evaluation, no fragments weighing more than 150g were generated and scattered more than 15m, so it was rated as excellent. In the safety 2 evaluation, fragments were scattered more than 15m, so the overall evaluation was poor. The fragmentation state of the container body was rated as excellent, as the container body did not break into two. The drop strength of the container was rated as excellent.

[Comparative Example 11]
Except for the fact that no fragile portion was provided and the static internal pressure at which the container body breaks was changed to approximately 3.7 MPa, evaluation was performed in the same manner as in Comparative Example 10. The results are shown in Table 2 below.
The container's mass was approximately 10.1 kg, so its transportability was rated as excellent. In the safety 1 evaluation, no fragments weighing more than 150g were generated and scattered more than 15m, so it was rated as excellent. In the safety 2 evaluation, fragments were scattered more than 15m, so the overall evaluation was poor. The fragmentation state of the container body was rated as excellent, as the container body did not break into two. The drop strength of the container was rated as excellent.

[Example 1]
The thickness of the cylinder was 0.5 mm, a prepreg (fiber-reinforced resin plate) was used in which the fibers were arranged so that the ratio of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was 2%, the pipe-making method was changed to a flat roll as shown in Figure 6, no fragile portion was provided, and the static internal pressure at which the container body breaks was changed to approximately 0.2 MPa, and evaluation was performed in the same manner as in Comparative Example 11. The results are shown in Table 3 below.
The container's mass was approximately 9.6 kg, so portability was rated as excellent. In the safety ratings of 1 and 2, no fragments weighing more than 150 g were scattered more than 15 m, so safety was rated as good for both. However, in the container drop strength rating, air leakage occurred from part of the container body after the container was dropped, so the rating was fair. Fiber-reinforced resin is weak in directions other than the direction of the fibers, and could not withstand the impact of a drop.

[Example 2]
Except for changing the thickness of the cylindrical body to 2.0 mm and changing the static internal pressure at which the container body breaks to about 0.8 MPa, the evaluation was performed in the same manner as in Example 1. The results are shown in Table 3 below.
The container's mass was approximately 10.1 kg, so its transportability was rated as excellent. In the safety ratings of 1 and 2, no fragments weighing more than 150 g were scattered more than 15 m, so the safety ratings were both excellent. However, the container's drop strength was rated as fair. Fiber-reinforced resin is weak in directions other than the direction of the fibers, and even when the thickness was increased, it could not withstand the impact of a drop.

[Example 3]
A prepreg (fiber-reinforced resin plate) in which fibers were arranged so that the ratio of tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was 1965% was used, the pipe-making method was changed to a flat roll as shown in Fig. 6, a broken line slit was drilled in the axial direction of the cylinder of the container body over a length of 900 mm with an interval of 97 mm at the cut portion and 3 mm at the joint portion, a coating agent was poured into the gap of the through hole in the weak portion to seal it, and evaluation was performed in the same manner as in Example 2, except that the static internal pressure at which the container body breaks was changed to approximately 1.2 MPa. The results are shown in Table 3 below.
In the evaluation of Safety 1, there were no fragments over 150g that were scattered more than 15m, so the safety was rated as good. In the evaluation of Safety 2, there were no fragments over 150g that were scattered more than 15m, but the container body broke in the circumferential direction, and the container broke into two and scattered, so the overall evaluation was good and the state of fragmentation of the container body was bad. Safety 2 was rated as bad. The evaluation of drop strength was good, because the container broke when dropped from a height of 12m, and the contents were released outside the container. It was found that changing the direction of the fibers and increasing the strength in the circumferential direction too much makes the product weak in terms of safety and resistance to drop impact.

[Example 4]
The materials of the container were glass fiber and epoxy resin, the tube-making method was winding, the direction of the fibers during winding was changed for each winding layer, the winding angle for the inner 0.5 mm was 30 degrees and for the outer 1.5 mm was 65 degrees, the thickness of the cylinder was 2 mm, the shape of the fragile part was grooved, a groove 2 mm wide and 1.7 mm deep and 900 mm long was drilled from the outside of the cylinder, the ratio of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was 242%, the static internal pressure at which the container body breaks was changed to about 0.7 MPa, and no sealant was used, and the evaluation was performed in the same manner as in Comparative Example 9. The results are shown in Table 3 below.
The container's mass was approximately 10.1 kg, so portability was rated as excellent. Safety 1 was rated as excellent, but safety 2 was rated as excellent because no fragments weighing more than 150 g were generated and scattered more than 15 m. Drop strength was rated as excellent because air leaked from part of the container body after a drop of 1.5 m.
It was found that changing the fiber direction and increasing the circumferential strength too much made the product vulnerable to safety and impact shocks from falling.

[Example 5]
A single broken line slit was drilled in the axial direction of the cylinder of the container body over a length of 900 mm, with an interval of 90 mm at the cut portion and 10 mm at the joint portion, and a coating agent was poured into the gap of the through hole in the fragile portion to seal it, and evaluation was performed in the same manner as in Comparative Example 10, except that the static internal pressure at which the container body breaks was changed to approximately 0.4 MPa. The results are shown in Table 3 below.
The container's mass was approximately 10.1 kg, so its transportability was rated as excellent. In the safety 1 evaluation, no fragments weighing more than 150 g were generated that flew more than 15 m, and the container body was not broken into two, so its safety was rated as excellent. In the safety 2 evaluation, the container opened widely from the fragile part, the lid did not fly off, and the container body was not broken into two, so its safety was rated as excellent. The container's drop strength was rated as excellent.

[Example 6]
Except for sealing the gap of the through hole in the fragile portion by filling it with an adhesive, the evaluation was performed in the same manner as in Example 5. The results are shown in Table 3 below.
As in Example 1, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 7]
Except for sealing the gap of the through hole in the weak portion with aluminum tape, the evaluation was performed in the same manner as in Example 5. The results are shown in Table 3 below.
As in Example 1, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 8]
The fragile portion was shaped like a groove, with a width of 2 mm and a depth of 1.5 mm provided from the outside of the cylinder, the static internal pressure at which the container body breaks was changed to approximately 0.9 MPa, and evaluation was performed in the same manner as in Example 5, except that no sealing material was used. The results are shown in Table 3 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 9]
Except for the fact that the shape of the fragile portion was a broken line and that the processed portion was a groove rather than a through hole, the evaluation was performed in the same manner as in Example 8. The results are shown in Table 3 below.
As in Example 8, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 10]
The evaluation was the same as in Example 9, except that the pipe-making method was flat rolls, the ratio of the tensile strength in the circumferential direction of the cylinder to the axial direction of the cylinder was 27%, the weak parts were not welded but the tensile strength in the circumferential direction of the base material was 12% of the tensile strength of the weak parts, the static internal pressure at which the container body breaks was changed to approximately 0.4 MPa, and the sealant was replaced with a paint. The results are shown in Table 3 below.
As in Example 9, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 11]
The evaluation was carried out in the same manner as in Example 9, except that the pipe manufacturing method was changed to spiral seam welding, the ratio of the tensile strength in the circumferential direction of the cylinder to that in the axial direction of the cylinder was changed to 27%, and the weak portion was replaced by a spiral weld. The results are shown in Table 3 below.
As in Example 9, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 12]
The evaluation was carried out in the same manner as in Example 5, except that the fiber contained in the container body was changed to 24 mm and the tensile strength of the base material in the circumferential direction was changed to 6% of the tensile strength of the fragile portion. The results are shown in Table 3 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 13]
Except for the fact that the weakened portion was provided in a spiral shape, evaluation was performed in the same manner as in Example 5. The results are shown in Table 3 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 14]
Except for replacing the fibers with pulp fibers, evaluation was carried out in the same manner as in Example 8. The results are shown in Table 4 below.
As in Example 8, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 15]
Except for changing the shape of the cylindrical portion of the container body to a square, the evaluation was the same as in Example 5. The results are shown in Table 4 below. Since the container mass was approximately 10 kg, the transportability was rated as ⊚. Safety 1 was rated as ⊚, and Safety 2 was rated as ⊚ because the corners and fragile parts of the container body cracked and opened, and no fragments weighing 150 g or more were generated and scattered 15 m or more. Drop strength was rated as ⊚.

[Example 16]
Except for replacing the fibers with stainless steel fibers, the evaluation was carried out in the same manner as in Example 5. The results are shown in Table 4 below. As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the drop strength rating was ⊚.

[Example 17]
Except for replacing the fibers with ceramic fibers, evaluation was carried out in the same manner as in Example 5. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 18]
Except for replacing the fibers with resin (aramid) fibers, evaluation was carried out in the same manner as in Example 5. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 19]
Except for replacing the fibers with carbon fibers, the evaluation was carried out in the same manner as in Example 5. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 20]
Except for changing the impregnating resin to POM (polyacetal) resin, evaluation was performed in the same manner as in Example 5. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 21]
Except for changing the impregnating resin to an unsaturated polyester resin, evaluation was performed in the same manner as in Example 5. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 22]
The evaluation was carried out in the same manner as in Example 5, except that the shape of the fragile portion was a broken line, through holes were provided so that the tensile strength of the base material was 6% of the tensile strength of the fragile portion, and a coating material was filled into the gaps of the through holes to seal them. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ◎, the safety 1 rating was ○, the safety 2 rating was ○, and the container drop strength rating was rated as ◎ because the coating agent was distorted and discolored, but no air leakage occurred.

[Example 23]
The pipe was evaluated in the same manner as in Comparative Example 9, except that the pipe-making method was winding, the fiber direction during winding was changed for each winding layer, the winding angle for the inner 1.0 mm was 35 degrees and for the outer 1.0 mm was 75 degrees, the ratio of tensile strength in the circumferential direction of the cylinder to that in the axial direction of the cylinder was 200%, and the static internal pressure at which the container body breaks was changed to approximately 1.8 MPa. The results are shown in Table 4 below.
The transportability was rated as excellent, the safety 1 rating was excellent, the safety 2 rating was excellent, and the container drop strength rating was excellent.

[Example 24]
The evaluation was carried out in the same manner as in Example 5, except that the fiber braid angle was set to 27 degrees, the ratio of the tensile strength in the circumferential direction of the cylinder to that in the axial direction of the cylinder was set to 10%, no fragile portion or coating agent was provided, and the static internal pressure at which the container body breaks was changed to approximately 1.9 MPa. The results are shown in Table 4 below.
As in Example 5, the transportability was rated as ⊚, the safety 1 rating was ◯, the safety 2 rating was ◯, and the container drop strength rating was ⊚.

[Example 25]
The evaluation was carried out in the same manner as in Example 8, except that the fiber braid angle was set to 53 degrees, the ratio of the tensile strength in the circumferential direction of the cylinder to that in the axial direction of the cylinder was set to 199%, and the static internal pressure at which the container body breaks was changed to approximately 1.1 MPa. The results are shown in Table 4 below.
The transportability was rated as excellent, the safety 1 rating was excellent, the safety 2 rating was excellent, and the container drop strength rating was excellent.

[Example 26]
Except for changing the thickness of the cylindrical portion to 3.0 mm, the evaluation was performed in the same manner as in Example 5. The results are shown in Table 4 below.
Since the container mass was approximately 11.4 kg, the portability was rated as "good", the safety 1 rating was "good", the safety 2 rating was "good", and the container drop strength rating was "excellent".
The safety test results in Example 26 are shown diagrammatically in FIG. 10 (3).

From the above results, it can be seen that, compared to the comparative example in which the container body is made of metal and further includes a fragile portion, and the comparative example in which it is solely specified that the container body contains fiber-reinforced plastic, the embodiment in which the container body contains fiber-reinforced plastic and further specifies a limit static internal pressure has high airtightness and operability, and is superior in being able to reduce damage to the surrounding area when explosives detonate, etc.
Furthermore, the drop strength can be adjusted by providing a fragile portion to the container body, and the separation of the container can be adjusted by adjusting the ratio of axial and circumferential tensile strengths of the cylindrical portion.
In this way, by satisfying all of the conditions of fiber-reinforced plastic + limit static internal pressure + fragile portion + tensile strength ratio, it is possible to achieve a particularly high drop strength while adjusting the separation and drop strength of the container. In particular, such a high drop strength cannot be achieved by a configuration that satisfies only the fragile portion or the tensile strength ratio, but can be achieved by combining them.

The above describes an embodiment of the present invention, but the present invention is not limited to this and can be modified as appropriate without departing from the spirit of the invention.

The tube of the container body according to the present invention is made of a fiber-reinforced resin material that is strong in the axial direction of the tube and easily breaks in the circumferential direction, and the container body is structured optimally or a weak part is provided in the container body, and a sealant is provided in the gap of the weak part so that the container body starts to break at a predetermined pressure. By using a fiber-reinforced resin ammunition container, it is possible to maintain drop strength and airtightness under normal conditions, while opening at a low pressure in an emergency when explosives ignite inside the container, and to reduce the maximum pressure generated inside the container. This makes it possible to more reliably reduce the risk of the container exploding, and as a result, to more reliably reduce the impact on the surroundings. In addition, in an emergency when explosives explode due to being hit from outside the container, the shape of the scattered fragments can be made small and lightweight, thereby reducing the lethal energy of the scattered fragments, and the fibers can be oriented in a direction close to the axis of the tube, which prevents the container body from flying. As a result, the impact on the surroundings can be more reliably reduced. In other words, in the ammunition container according to the present invention, even if the internal explosives ignite or explode, the impact on the surroundings can be more reliably reduced. Furthermore, since it can be made lighter than a metal material, it can be more easily transported. Therefore, the present invention can be suitably used as an ammunition container.

REFERENCE SIGNS LIST 1 Ammunition container 2 Cylindrical portion 3 Bottom portion 4 Container body 5 Lid 10 Weakened portion A Weakened portion length B Gap between through holes C Length per through hole D Joint length between through holes E Fiber F Resin G Lid

Claims (6)

A container body having a cylindrical portion and a bottom portion closing one of both ends of the cylindrical portion, and a lid body closing the other opening of both ends of the cylindrical portion,
The cylindrical portion includes a fiber-reinforced plastic, and the limit static internal pressure of the cylindrical portion is 0.2 to 2.0 MPa;
The tubular portion includes at least one weakened portion,
The fibers of the fiber-reinforced plastic are arranged by a filament winding method, and
The ratio of the tensile strength in the circumferential direction to the axial direction of the cylindrical portion is 2 to 250%.
An ammunition container comprising: The ammunition container according to claim 1, wherein the fragile portion is sealed with a sealant. The ammunition container according to claim 1 or 2, wherein the fragile portion has a linear structure, a groove structure, a thin-walled structure, a portion that does not contain fibers, or a structure of a combination thereof. The ammunition container according to any one of claims 1 to 3, wherein the fibers of the fiber-reinforced plastic include at least one selected from the group consisting of glass fibers, metal fibers, pulp fibers, ceramic fibers, resin fibers, carbon fibers, and wood fibers. The ammunition container according to any one of claims 1 to 4, wherein the plastic of the fiber-reinforced plastic contains at least one selected from the group consisting of epoxy resin, polyacetal resin, vinyl chloride, unsaturated polyester resin, acrylic resin, polycarbonate resin, and phenolic resin. The following steps:
forming a plastic tube having reinforcing fibers disposed therein by a filament winding process;
forming at least one weakened portion in the obtained tubular portion; and
a step of closing one of both ends of the obtained cylindrical portion with a bottom portion and closing the other opening with a lid;
1. A method of making an ammunition container comprising:
A method for manufacturing an ammunition container, characterized in that the resulting cylindrical portion has a limit static internal pressure of 0.2 to 2.0 MPa and a ratio of the tensile strength in the circumferential direction to the axial direction of the cylindrical portion is 2 to 250%.

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