Composite baffle for recoilless gun rear-spray ammunition and preparation method thereof

Abstract

The present invention discloses a composite baffle for recoilless gun rear-jet ammunition and a preparation method thereof. Prepreg layer: a plain square carbon fiber prepreg is thinly coated with modified epoxy resin to obtain a first fiber layer; a unidirectional carbon fiber prepreg tape and a glass fiber prepreg are layered and thinly coated with modified epoxy resin to obtain a second fiber layer; a unidirectional carbon fiber prepreg tape and a carbon fiber prepreg are layered and thinly coated with modified epoxy resin to obtain a third fiber layer; the first fiber layer, the second fiber layer and the third fiber layer are sequentially stacked together from top to bottom to obtain a composite layer; the composite layer is molded and cooled to obtain a composite baffle. The composite baffle prepared by the present invention is dispersed into a plurality of 0.1-0.2 mm fiber sheets under the action of gunpowder gas. The sheets fall when encountering wind resistance during flight and will not pose a threat to the rear personnel.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a composite baffle for recoilless gun rear-spray ammunition and a preparation method thereof. Background Art

[0002] Recoilless guns are guns that have no recoil when firing. They are mainly used to directly attack armored targets, suppress and destroy manpower and firearms. They have made great contributions in the history of anti-tank warfare. Principle of recoilless guns: Recoilless gun ammunition consists of a warhead, a shell and a baffle at the bottom of the shell. When the ammunition is fired, the gunpowder ignites in the cartridge case, and the gunpowder gas instantly generates pressure. When the chamber pressure reaches a certain pressure, the warhead flies forward, and the baffle at the bottom of the cartridge case flies backward under the action of the gunpowder gas. The front and rear thrusts offset each other, and no recoil is generated during the entire firing process. In order to prevent the baffle from causing harm to the rear personnel when it sprays backward, the baffle is required to not fly too far or break into small pieces to reduce the flying distance.

[0003] In recent years, my country's ammunition has been continuously developed, and various caliber recoilless guns have emerged. There are currently two types of recoilless gun equipment, and the baffles are realized by various schemes. The baffle of the 93mm recoilless gun is made of alloy aluminum through precision machining by a machining center. A parachute is added during use. When the baffle is pressed and opened to fly backwards, the parachute opens instantly to slow down the flight distance of the metal baffle. The advantage of this scheme is that it is less affected by external environmental factors during use, the chamber pressure is stable, and the initial velocity of the bullet is stable; the disadvantage is that the parachute is not easy to open when a malfunction occurs, the stability is poor, and the alloy aluminum has a high density and a long flight distance, which is easy to cause harm to people around. The thermoplastic plastic baffle used in the 82mm recoilless gun has stress cracking grooves carved on the surface. When the baffle is pressed and opened, the plastic baffle can be broken into small particles along the stress grooves, and the flight speed and distance are slowed down by the wind speed. The advantages of this scheme are small broken particles and high safety factor; the disadvantage is that when shooting in a high temperature environment, the toughness of the plastic baffle increases, the broken pieces increase, and there are certain safety hazards. Therefore, a composite baffle with high safety factor, low toughness but high strength and rigidity is needed. Summary of the invention

[0004] In view of the above-mentioned prior art, the purpose of the present invention is to provide a composite baffle for recoilless gun rear-spray ammunition and a preparation method thereof. The composite baffle prepared by the present invention is dispersed into a plurality of 0.1-0.2 mm fiber sheets under the action of gunpowder gas. The sheets fall when encountering wind resistance during flight and will not pose a threat to the rear personnel.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A first aspect of the present invention provides a method for preparing a composite baffle for a recoilless gun rear-spray ammunition, comprising the following steps:

[0007] (1) Prepreg layer: plain square carbon fiber prepreg is layered in the directions of (-45°, +45°) and (0°, 90°), and each layer of plain square carbon fiber prepreg is thinly coated with modified epoxy resin to obtain a first fiber layer; unidirectional carbon fiber prepreg tape and glass fiber prepreg are layered alternately in the directions of (-45°, +45°) and (0°, 90°), and each layer of unidirectional carbon fiber prepreg tape and glass fiber prepreg is thinly coated with modified epoxy resin to obtain a second fiber layer; unidirectional carbon fiber prepreg tape and carbon fiber prepreg are layered alternately in the directions of (-45°, +45°) and (0°, 90°), and each layer of unidirectional carbon fiber prepreg tape and carbon fiber prepreg is thinly coated with modified epoxy resin to obtain a third fiber layer;

[0008] (2) The first fiber layer, the second fiber layer and the third fiber layer are stacked together from top to bottom to obtain a composite layer; the composite layer is molded and cooled to obtain a composite baffle.

[0009] Preferably, in step (1), the first fiber layer comprises 5 to 8 layers of plain woven square carbon fiber prepreg fabrics; the second fiber layer comprises 5 to 6 layers of unidirectional carbon fiber prepreg tapes and 4 to 8 layers of glass fiber prepreg fabrics; and the third fiber layer comprises 5 to 6 layers of unidirectional carbon fiber prepreg tapes and 5 to 6 layers of carbon fiber prepreg fabrics.

[0010] Preferably, in step (1), the surface density of the plain woven square carbon fiber prepreg is 200 g / m 2 The surface density of the unidirectional carbon fiber prepreg tape is 150g / m 2 The surface density of the carbon fiber prepreg is 140g / m 2 The surface density of the glass fiber prepreg is 200g / m 2 .

[0011] Preferably, in step (1), the modified epoxy resin thinly coated on the plain woven square carbon fiber prepreg accounts for 40% of the mass of the plain woven square carbon fiber prepreg; in the second fiber layer, the modified epoxy resin thinly coated on the unidirectional carbon fiber prepreg tape accounts for 10% of the mass of the unidirectional carbon fiber prepreg tape, and the modified epoxy resin thinly coated on the glass fiber prepreg accounts for 20% of the mass of the glass fiber prepreg; in the third fiber layer, the modified epoxy resin thinly coated on the unidirectional carbon fiber prepreg tape accounts for 20% of the mass of the unidirectional carbon fiber prepreg tape, and the modified epoxy resin thinly coated on the carbon fiber prepreg accounts for 20% of the mass of the carbon fiber prepreg.

[0012] Preferably, in step (1), the plain woven carbon fiber prepreg, unidirectional carbon fiber prepreg tape and carbon fiber prepreg are all M40J high modulus carbon fiber materials; and the glass fiber prepreg is SW80B-90a high strength glass fiber material.

[0013] Preferably, in step (1), the modified epoxy resin is prepared by the following method:

[0014] S01. The activated carbon powder was dispersed in hexadecyltrimethylammonium chloride, heated with stirring, filtered and dried to obtain a modified activated carbon powder;

[0015] S01. Disperse chopped carbon fiber and modified activated carbon powder in chloroform, add epoxy resin and continue stirring, and distill off the chloroform to obtain modified epoxy resin.

[0016] Preferably, the heating temperature is 60-70° C. and the heating time is 0.5-1 h; the mass ratio of the chopped carbon fiber, the modified activated carbon powder and the epoxy resin is 2.5:2:5.5; and the model of the epoxy resin is Three Bond 2210.

[0017] Preferably, in step (2), the molding temperature is 145° C., the time is 140 min, and the pressure is 10 MPa.

[0018] The second aspect of the present invention provides a composite baffle obtained by the above preparation method.

[0019] The thickness of the composite baffle is 6 to 8 mm.

[0020] A third aspect of the present invention provides application of a composite baffle in recoilless gun firing.

[0021] Beneficial effects of the present invention:

[0022] (1) The composite material prepared by the present invention has a good molding process, high strength and rigidity, and the modified epoxy resin used has the characteristics of high strength and low toughness, and is easily broken under the action of gunpowder gas.

[0023] (2) The composite baffle prepared by the present invention is dispersed into a plurality of 0.1-0.2 mm fiber flakes under the action of gunpowder gas. The flakes fall down when encountering wind resistance during flight and will not pose a threat to the personnel behind. This provides a new idea for the baffle used for recoilless gun rear-spray ammunition.

[0024] (3) The preparation method of the present invention is simple, the baffle is light in weight and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Photos of the 82mm simulated gun firing test;

[0026] Figure 2 : Photo of the composite baffle before shooting;

[0027] Figure 3 : Photograph of the composite baffle prepared in Example 2 after shooting;

[0028] Figure 4 : Photograph of the composite baffle prepared in Comparative Example 4 after shooting;

[0029] Figure 5 : Photograph of the composite baffle prepared in Comparative Example 5 after shooting;

[0030] Figure 6 : Photograph of the composite baffle prepared in Comparative Example 6 after shooting. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0032] As introduced in the background technology section, although the plastic baffle can be broken into small particles along the stress groove, when shooting in a high temperature environment, the toughness of the plastic baffle increases, the broken pieces become larger, and there is a safety hazard.

[0033] Based on this, the purpose of the present invention is to provide a composite baffle for recoilless gun rear-spray ammunition and a preparation method thereof. According to the stress conditions of the baffle, the present invention finally selects M40J high modulus carbon fiber material and SW80B-90a high strength glass fiber material as raw materials. The epoxy resin needs to have high strength and low toughness. By adding chopped carbon fiber and modified activated carbon, the toughness of the epoxy resin is reduced and the strength is increased. The interlaminar force of the composite baffle finally prepared is 15-23Kg / cm 2 The baffle must be able to withstand a chamber pressure of 6-10MPa when in use, and the glass fiber cloth and carbon fiber cloth must be instantly delaminated when opened, ensuring that the rear spray hazard boundary meets the index requirements.

[0034] The present invention adopts 150g / m 2 Unidirectional carbon fiber prepreg, 200g / m 2 Plain woven carbon fiber prepreg, 140g / m 2 The glass fiber prepreg cloth is combined with unidirectional carbon fiber prepreg tape ply in the direction of (-45°, +45°), and the surface of the product uses plain square carbon fiber prepreg cloth ply, mainly in the directions of (-45°, +45°) and (0°, 90°), which improves the overall force uniformity of the product. The internal unidirectional carbon fiber prepreg tape and glass fiber prepreg cloth are alternately laid, which can not only meet the rigidity required by the baffle, but also improve the toughness of the baffle.

[0035] The toughness of the baffle is improved by using carbon fiber cloth and glass fiber cloth to ensure that the baffle as a whole will not break under the action of gunpowder gas during use. The modified epoxy resin reduces the toughness to ensure that it will break under the action of gunpowder gas during use, releasing the carbon fiber cloth and glass fiber cloth, so that they can be separated instantly. The thin carbon fiber cloth and glass fiber cloth cannot fly too far under the action of wind resistance, and will not cause harm to the personnel behind.

[0036] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0037] Note: The epoxy resin used in the present invention is Japanese three-bond TB2210 single-component epoxy resin glue;

[0038] Plain woven square carbon fiber prepreg, unidirectional carbon fiber prepreg tape and carbon fiber prepreg are obtained by different laying methods of M40J high modulus carbon fiber materials, and are all purchased from Weihai Guangwei Composite Materials Co., Ltd.;

[0039] The glass fiber prepreg was prepared from SW80B-90a high-strength glass fiber material, and the glass fiber prepreg was purchased from Fengxiang County Glass Fiber Co., Ltd.;

[0040] The length of the chopped carbon fiber is 0.5 to 2 cm.

[0041] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0042] Embodiment 1:

[0043] S01. 20 g of activated carbon powder (40-50 mesh) was slowly dispersed in hexadecyltrimethylammonium chloride, stirred at 65 ° C for 1 h, and the upper layer solution was filtered after standing and stratified, and vacuum dried at 80 ° C for 3 h to obtain modified activated carbon powder;

[0044] S02. Disperse 25 g of chopped carbon fiber (T700) and 20 g of modified activated carbon powder in 200 mL of chloroform, add 55 g of TB2210 epoxy resin and continue stirring, and distill off the chloroform to obtain a modified epoxy resin.

[0045] Comparative Example 1

[0046] 25 g of chopped carbon fiber (T700) was dispersed in 200 mL of chloroform, and 55 g of TB2210 epoxy resin was added and continued to stir. The chloroform was distilled off to obtain a modified epoxy resin.

[0047] Comparative Example 2

[0048] 25 g of chopped carbon fiber (T700) and 20 g of activated carbon powder (40-50 mesh) were dispersed in 200 mL of chloroform, 55 g of TB2210 epoxy resin was added and continued to stir, and the chloroform was distilled off to obtain a modified epoxy resin.

[0049] Comparative Example 3

[0050] S01. 20 g of carbon black powder (40-50 mesh) was slowly dispersed in hexadecyltrimethylammonium chloride, stirred at 65 ° C for 1 h, and the upper layer solution was filtered after standing and stratified, and vacuum dried at 80 ° C for 3 h to obtain modified carbon black powder;

[0051] S01. Disperse 25 g of chopped carbon fiber (T700) and 20 g of modified carbon black powder in 200 mL of chloroform, add 55 g of TB2210 epoxy resin and continue stirring, and distill off the chloroform to obtain a modified epoxy resin.

[0052] Test Example 1

[0053] According to the standard "GB / T 2567 7-2021 Test method for properties of resin castings", the modified epoxy resins prepared in Example 1 and Comparative Examples 1 to 2 were cast and cured, and samples were taken for toughness and strength testing. The results are shown in Table 1.

[0054] Table 1

[0055] Tensile strength MPa <![CDATA[Impact toughness J / cm 2 > Example 1 72.1 21.3 Comparative Example 1 73.5 25.7 Comparative Example 2 72.4 24.1 Comparative Example 3 78.7 28.5

[0056] It can be seen from Table 1 that although the strength of the epoxy resin sample prepared in Example 1 is not as good as that of the epoxy resin samples prepared in Comparative Examples 1 and 3, its toughness is significantly reduced. Compared with the degree of strength reduction, the toughness is reduced more. In addition, the strength of the epoxy resin in Example 1 is not reduced much compared with Comparative Examples 1 to 3, which does not affect the strength requirements for shooting. This shows that the toughness of the epoxy resin can be reduced by adding activated carbon, so that the fiber cloth in the baffle can be broken faster and more after the baffle is stressed, and the fiber cloth is dispersed into several fiber flakes, which greatly reduces the personal safety of the operator during shooting.

[0057] Example 2

[0058] 1. Material selection

[0059] (1) Selection of fiber cloth

[0060] The specification is 150g / m 2 Unidirectional carbon fiber prepreg tape and 200g / m 2 Plain woven carbon fiber prepreg, 140g / m 2Glass fiber prepreg is the main raw material. Glass fiber prepreg is made of SW80B-90a high-strength glass fiber material, and plain square carbon fiber prepreg, unidirectional carbon fiber prepreg tape and carbon fiber prepreg are all made of M40J high modulus carbon fiber material.

[0061] (2) Carbon fiber prepreg cutting

[0062] Use a cutting machine to cut out carbon fiber prepregs and glass fiber prepregs of different shapes and models; tear off the plastic film on the surface of the cut blanks and place them neatly in a certain order for later use;

[0063] 2. Mold processing

[0064] (1) Clean the residual resin on the mold surface with a copper scraper and wipe it clean with a cotton cloth;

[0065] (2) Use cotton cloth to dip an appropriate amount of release agent MB5091H, apply it evenly on the surface of the mold cavity, and let it dry at room temperature for 10 to 20 minutes;

[0066] (3) Quality control point: Apply the release agent evenly.

[0067] 3. Product Lamination

[0068] (1) Heat the mold temperature to 40-50°C and the ambient temperature to 20-25°C;

[0069] (2) Place the cut blanks of different specifications on the mold in order:

[0070] a. Take the cut 200g / m 2 3-4 layers of plain square carbon fiber prepreg blanks are laid flat in the mold cavity in sequence according to (-45°, +45°) and (0°, 90°), and the carbon fiber prepreg is flattened with a pressing wheel; 40% of the modified epoxy resin prepared in Example 1 is thinly coated on the plain square carbon fiber prepreg.

[0071] b. 150g / m 2 Unidirectional carbon fiber prepreg tape 5-6 layers, the material is distributed in the sub-outer layer, mainly in the (-45°, +45°) direction, the resin content is 10%,; 200g / m 2 The glass fiber prepreg is laid in the direction of (0°, 90°), with 4 to 10 layers, and the two materials are laid alternately. 10% of the modified epoxy resin is thinly coated on the unidirectional carbon fiber prepreg, and 20% of the modified epoxy resin prepared in Example 1 is thinly coated on the glass fiber prepreg.

[0072] c. 150g / m 2 5-6 layers of unidirectional carbon fiber prepreg tape, laid in (-45°, +45°) direction, 140g / m 2The carbon fiber prepreg is laid in the direction of (0°, 90°), with 5 to 6 layers, and the two materials are laid alternately. 20% of the modified epoxy resin prepared in Example 1 is thinly coated on each layer.

[0073] Control the thickness of the fabric layer to 6-8mm.

[0074] 4. Curing

[0075] (1) Place the mold in a press and increase the pressure to 0.1 MPa for preheating at a temperature of 90 to 100°C;

[0076] (2) After preheating reaches the required temperature, the pressure is increased to 10 MPa, the equipment temperature is adjusted to 145°C, and the mold temperature is kept warm for 140 minutes before the mold is removed. When the mold temperature drops below 60°C, the mold is opened and the product is removed;

[0077] 5. Machining and surface treatment

[0078] (1) The baffle plate is CNC machined according to the drawing requirements;

[0079] (2) Grind the outer edge of the product with sandpaper;

[0080] (3) Use laser to print product number and batch number.

[0081] (4) Spray paint twice.

[0082] Comparative Example 4

[0083] The difference from Example 2 is:

[0084] The modified epoxy resin prepared in Comparative Example 1 was thinly coated on each fiber cloth.

[0085] Comparative Example 5

[0086] The difference from Example 2 is:

[0087] The modified epoxy resin prepared in Comparative Example 2 was thinly coated on each fiber cloth.

[0088] Comparative Example 6

[0089] The difference from Example 2 is:

[0090] The modified epoxy resin prepared in Comparative Example 3 was thinly coated on each fiber cloth.

[0091] Test Example 2

[0092] The composite baffles prepared in Example 2 and Comparative Examples 4 to 6 were subjected to a recoilless gun firing test, and the specific firing process is as follows:

[0093] 1. Fix the 82mm recoilless simulated gun on the bracket (see Figure 1), remove the muzzle screw sleeve, install the composite baffles prepared in Example 2 and Comparative Examples 3 to 5 in the limiting groove, and install the muzzle screw sleeve.

[0094] 2. The high-pressure chamber inside the barrel is filled with high-pressure gas. When the pressure reaches 11MPa, the inflation is stopped. The air release valve is opened manually, and the high-pressure gas instantly enters the gas balance chamber. When the pressure reaches 8-9MPa, the baffle is pressurized and ejected.

[0095] 3. Under the impact of high-speed and high-pressure gas, the baffle will break into pieces instantly when it is ejected, and fall to the ground after flying 10-20 meters without causing any harm to personnel.

[0096] See the photo of the front baffle for shooting Figure 2 , see the photo of the rear guard after shooting Figures 3 to 6 .

[0097] according to Figures 2 to 6 It can be seen that after shooting, the baffles prepared in Example 2 are all dispersed into thin sheets, while some of the baffles prepared in Comparative Examples 4 to 6 are not dispersed, indicating that the modified resin prepared in Example 1 can reduce the toughness of the baffles and separate them from the fiber cloth more thoroughly, making the dispersion of the fiber sheets more thorough, thereby minimizing the harm to the rear operators.

[0098] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a composite baffle for recoilless gun rear-spray ammunition, It is characterized in that The following steps are involved: (1) Prepreg layer: lay the plain square carbon fiber prepreg in the direction of (-45º, +45º) and (0º, 90º) in turn, and thinly coat the modified epoxy resin on each layer of the plain square carbon fiber prepreg to obtain the first fiber layer; lay the unidirectional carbon fiber prepreg tape and the glass fiber prepreg in the direction of (-45º, +45º) and (0º, 90º) in turn, and thinly coat the modified epoxy resin on each layer of the unidirectional carbon fiber prepreg tape and the glass fiber prepreg to obtain the second fiber layer; lay the unidirectional carbon fiber prepreg tape and the carbon fiber prepreg in the direction of (-45º, +45º) and (0º, 90º) in turn, and thinly coat the modified epoxy resin on each layer of the unidirectional carbon fiber prepreg tape and the carbon fiber prepreg to obtain the third fiber layer; The modified epoxy resin is prepared by the following method: S01. The activated carbon powder was dispersed in hexadecyltrimethylammonium chloride, heated with stirring, filtered and dried to obtain a modified activated carbon powder; S02. The chopped carbon fibers and modified activated carbon powder were dispersed in chloroform, epoxy resin was added and stirred continuously, and chloroform was removed by distillation to obtain a modified epoxy resin; (2) The first fiber layer, the second fiber layer, and the third fiber layer are stacked together from top to bottom to obtain a composite layer; the composite layer is molded and cooled to obtain a composite baffle.

2. The preparation method according to claim 1, It is characterized in that In step (1), the first fiber layer comprises 5 to 8 layers of plain woven square carbon fiber prepreg fabrics; the second fiber layer comprises 5 to 6 layers of unidirectional carbon fiber prepreg tapes and 4 to 8 layers of glass fiber prepreg fabrics; and the third fiber layer comprises 5 to 6 layers of unidirectional carbon fiber prepreg tapes and 5 to 6 layers of carbon fiber prepreg fabrics.

3. The preparation method according to claim 1, It is characterized in that In step (1), the surface density of the plain square carbon fiber prepreg is 200g / m 2 The surface density of the unidirectional carbon fiber prepreg tape is 150g / m 2 The surface density of the carbon fiber prepreg is 140g / m 2 The surface density of the glass fiber prepreg is 200g / m 2 .

4. The preparation method according to claim 1, It is characterized in that In step (1), the modified epoxy resin thinly coated on the plain woven square carbon fiber prepreg accounts for 40% of the mass of the plain woven square carbon fiber prepreg; in the second fiber layer, the modified epoxy resin thinly coated on the unidirectional carbon fiber prepreg tape accounts for 10% of the mass of the unidirectional carbon fiber prepreg tape, and the modified epoxy resin thinly coated on the glass fiber prepreg accounts for 20% of the mass of the glass fiber prepreg; in the third fiber layer, the modified epoxy resin thinly coated on the unidirectional carbon fiber prepreg tape accounts for 20% of the mass of the unidirectional carbon fiber prepreg tape, and the modified epoxy resin thinly coated on the carbon fiber prepreg accounts for 20% of the mass of the carbon fiber prepreg.

5. The preparation method according to claim 1, It is characterized in that In step (1), the plain woven square carbon fiber prepreg cloth, unidirectional carbon fiber prepreg tape and carbon fiber prepreg cloth are all M40J high modulus carbon fiber materials; and the glass fiber prepreg cloth is SW80B-90a high strength glass fiber material.

6. The preparation method according to claim 1, It is characterized in that In step S01, the heating temperature is 60-70°C and the time is 0.5-1h; in step S02, the mass ratio of the chopped carbon fiber, the modified activated carbon powder and the epoxy resin is 2.5:2:5.5; the model of the epoxy resin is Three Bond 2210.

7. The preparation method according to claim 1, It is characterized in that In step (2), the molding temperature is 145° C., the time is 140 min, and the pressure is 10 MPa.

8. The composite baffle obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the composite baffle according to claim 8 in firing a recoilless gun.

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