Cartridge case and machining process of cartridge case

Abstract

The invention relates to the technical field of bullet manufacturing, in particular to a cartridge case and a machining process of the cartridge case, and particularly provides the cartridge case which comprises a polymer cartridge case body and a metal base. The polymer cartridge case comprises a rear end and a front end which are integrally formed, an inclination is arranged on the inner wall corresponding to the rear end, the inclination direction is that the rear end points to the front end, and the thickness of the case wall at the rear end is gradually reduced until the joint of the rear end and the front end reaches the minimum value; the metal base is fixed with the port at the rear end in an insert injection molding manner; and the front end is matched with the warhead. According to the invention, the defects of high cost, no high temperature resistance, tedious working procedures and low quality caused by gluing of glue and the polymer cartridge case are effectively overcome. Meanwhile, due to the inclination design of the inner wall of the rear end, stripping is easy, the explosive loading amount can be increased, and the performance of the bullet is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bullet manufacturing, and particularly to a cartridge case and a processing technology thereof. Background Art

[0002] The cartridge case is one of the most important components of a bullet. It is used to contain the propellant and connect the bullet head and the primer together. During firing, it also has to withstand the pressure of the gunpowder gas and the force of the firearm's automatic mechanism.

[0003] Since the conventional metal cartridge case is relatively heavy and also consumes rare metal resources, the existing cartridge cases adopt the polymer cartridge case solution. However, the polymer cartridge case solution has the following problems:

[0004] 1. Currently, all polymer cartridge case solutions use glue for bonding. The glue is expensive, and its strength decreases or even fails after high temperature. In addition, the glue bonding process is cumbersome, and the quality is difficult to guarantee and inspect;

[0005] 2. Currently, the propellant loading of polymer cartridge cases is relatively small, resulting in the manufactured bullets being difficult to meet the performance requirements of conventional bullet products.

[0006] The above defects are caused by the design and process defects of the cartridge case itself. Therefore, it is necessary to design a cartridge case and its processing technology. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides the following technical solutions:

[0008] According to the technical solution of the present invention, a cartridge case is provided, including:

[0009] A polymer cartridge case and a metal base;

[0010] The polymer cartridge case includes an integrally formed rear end and a front end. An inclination is provided on the inner wall corresponding to the rear end, and the inclination direction is from the rear end to the front end. The wall thickness of the shell at the rear end gradually decreases and reaches the minimum value at the junction of the rear end and the front end;

[0011] The metal base is fixed to the port of the rear end by insert injection molding;

[0012] The front end is adapted to the bullet head.

[0013] As an improvement of the above technical solution, the rear end is cylindrical, and the outer wall of the port of the rear end has a concavo-convex structure, which extends into the metal base and meshes with the inner wall of the metal base.

[0014] As an improvement of the above technical solution, the material of the polymer cartridge case is a high molecular polymer material.

[0015] According to another aspect of the present invention, there is also provided a processing technology for a cartridge case, comprising the following steps:

[0016] S100. Adopt an insert injection molding process to integrally injection mold the metal base and the polymer cartridge case, so that the rear end is formed to obtain a rough blank of the cartridge case;

[0017] S200. Perform secondary thermoforming on the obtained rough blank of the cartridge case in S100, so that the front end is formed to obtain a refined blank of the cartridge case;

[0018] S300. Trim the refined blank of the cartridge case obtained in S200, and a finished product can be obtained if it passes the inspection.

[0019] As an improvement of the above technical solution, in S100, the rough blank of the cartridge case is a cylindrical structure with one end open.

[0020] As an improvement of the above technical solution, in S200, the method of the secondary thermoforming comprises the following steps:

[0021] S210. Place the rough blank of the cartridge case into a heated forming mold, so that the rough blank of the cartridge case is heated to enter the highly elastic state;

[0022] S220. Shape the outer wall of the rough blank of the cartridge case in the highly elastic state. Through the action of the forming mold on the outer wall of the corresponding end of the rough blank of the cartridge case, it is shaped into the outer shape of the front end;

[0023] S230. Shape the inner wall of the rough blank of the cartridge case in the highly elastic state. Through a shaping pull rod extending into the rough blank of the cartridge case, the inner wall at the front end is shaped.

[0024] As an improvement of the above technical solution, in S220, when the end of the rough blank of the cartridge case without the metal base is heated to enter the highly elastic state, a force is applied to the rough blank of the cartridge case, so that the part entering the highly elastic state is gradually pressed into the cavity of the forming mold until the rough blank of the cartridge case moves a set distance.

[0025] As an improvement of the above technical solution, in S230, the shaping pull rod extends into the rough blank of the cartridge case before the rough blank of the cartridge case enters the highly elastic state, and cooperates with the cavity of the forming mold to realize the shaping of the front end.

[0026] Advantages of the present invention:

[0027] This solution effectively solves the defects of high cost, poor high-temperature resistance, cumbersome processes and low quality caused by adhesively fixing the metal base and the polymer cartridge case with glue. The slope design of the inner wall at the rear end not only facilitates demolding, but also can increase the charge amount and improve the performance of the bullet.

[0028] The manufacturing method provided by this solution adopts insert injection molding process, secondary thermoforming process and extrusion process, which optimizes the problems of large weight and metal resource consumption of traditional metal cartridges. And the whole process does not use glue bonding, with lower cost and higher product quality.

[0029] In addition, using a polymer cartridge can also eliminate the step difference between the metal base and the cartridge, improve the sealing performance, density and consistency during shooting. And since the whole cartridge is made of polymer material with lower hardness, it can greatly reduce the wear of the gun barrel and extend the service life of the barrel. Brief Description of the Drawings

[0030] Figure 1 is the existing cartridge structure one;

[0031] Figure 2 is the existing cartridge structure two;

[0032] Figure 3 is a schematic diagram of the structure of a cartridge Figure 1 ;

[0033] Figure 4 is a schematic diagram of the structure of a cartridge Figure 2 ;

[0034] Figure 5 is a schematic diagram of the structure of a cartridge Figure 3 ;

[0035] Figure 6 is a structural diagram of the mold and shaping mechanism in a cartridge processing technology.

[0036] Reference Numerals: 100, polymer cartridge; 110, rear end; 120, front end; 130, concave-convex structure; 200, metal base. Detailed Embodiments

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0038] Referring to the attached Figure 1-2 shown, Figure 1 is the existing cartridge structure one, in which the metal base and the polymer cartridge 100 are connected by adhesive bonding; Figure 2 is the existing cartridge structure two, in which the metal base and the polymer cartridge 100 are connected by adhesive bonding, and the rear end 110 is also adhesively bonded near the front end 120.

[0039] Currently, all polymer cartridge cases use glue for bonding. Glue is expensive, its strength decreases or even fails after high temperature, and the glue-bonding process is cumbersome, making it difficult to ensure and inspect the quality. Moreover, the powder charge of polymer cartridge cases is relatively small, resulting in the manufactured bullets being difficult to meet the performance requirements of conventional bullet products.

[0040] In the figure, the position a is the glue-bonding position, b is the position corresponding to the rear end 110, and c is the position corresponding to the front end 120.

[0041] See the appendix Figures 3-5 As shown, to solve the above technical problems, a cartridge case is provided, including: a polymer cartridge case 100 and a metal base 200.

[0042] For ease of understanding the technical solution of the present application, the integrally formed polymer cartridge case 100 is divided into two parts, namely the rear end 110 and the front end 120.

[0043] When the polymer cartridge case 100 is injection molded, on the one hand, it is to facilitate the removal of the material after molding, and on the other hand, it is to increase the internal space of the polymer cartridge case 100 to increase the powder charge. Therefore, a slope is provided on the inner wall corresponding to the rear end 110, and the slope direction is from the rear end 110 to the front end 120.

[0044] Preferably, the slope is greater than 0°. In practice, compared with the 12.7-caliber cartridge case, the slope value of the 7.62-caliber cartridge case is relatively larger.

[0045] Among them, the metal base 200 is fixed to the port of the rear end 110 by insert injection molding, which not only ensures the connection quality but also omits the process step of glue bonding.

[0046] Preferably, the outer shape of the rear end 110 is a cylindrical structure, and the outer wall of the port of the rear end 110 has a concavo-convex structure 130. The concavo-convex structure 130 extends into the metal base 200 and meshes with the inner wall of the metal base 200.

[0047] During injection molding, the concavo-convex structure 130 directly enters the metal base 200 through the molten material, so as to be fully combined with the metal base 200. After the material cools, it directly solidifies with the metal base 200. The setting of the concavo-convex structure 130 can further increase the firmness of the combination of the metal base 200 and the polymer cartridge case 100, making it more difficult for the two to separate.

[0048] The front end 120 is adapted to the bullet head. After the powder charge is completed inside the rear end 110, the front end 120 and the bullet head are assembled.

[0049] The material of the polymer cartridge case 100 is a polymer material, such as commonly used PPSU, PC, ABS, PEI, PSU, modified PA. Among them, Figure 4 and Figure 5 the cartridge case structures shown are also applicable to this solution.

[0050] The above technical solution effectively solves the defects of high cost, poor heat resistance, cumbersome processes and low quality caused by adhesively fixing the metal base 200 to the polymer cartridge case 200 with glue. The slope design of the inner wall of the rear end 110 not only facilitates demolding, but also increases the charge amount and improves the performance of the bullet.

[0051] See the appendix Figure 6 shown. According to another aspect of the present invention, a processing technology for the cartridge case is also provided, including the following steps:

[0052] S100. Adopt the insert injection molding process to integrally injection mold the metal base 200 and the polymer cartridge case 100, so that the rear end 110 is formed to obtain a rough cartridge case blank.

[0053] In this step, the finished product of the metal base 200 is integrally injection molded with the molten material through the insert injection molding process to obtain a rough cartridge case blank.

[0054] The rough cartridge case blank specifically refers to: the rear end 110 has been formed, and the rear end 110 is combined with the metal base 200, the front end 120 is not formed, and the overall structure is a cylindrical structure with one end open.

[0055] The insert injection molding process refers to pre-fixing the insert in an appropriate position in the injection mold, and then injecting plastic to form. After the mold is opened, the insert is tightly wrapped by the cooled and solidified plastic. In this solution, the metal base 200 is pre-fixed in the injection mold. This process is an existing technology and is not a technical feature claimed in this solution, so it will not be elaborated.

[0056] S200. Perform secondary thermoforming on the cartridge case blank obtained in S100 to form the front end 120 to obtain a refined cartridge case blank.

[0057] This step further processes the rough cartridge case blank to form the front end 120. The secondary thermoforming method is adopted in the further processing process.

[0058] Specifically, the secondary thermoforming method includes the following steps:

[0059] S210. Put the rough cartridge case blank into the heated forming mold, so that the rough cartridge case blank is heated and enters the highly elastic state.

[0060] Amorphous polymers with a Tg much higher than room temperature: Heat between Tg and Tf, then deform and shape into a certain shape. After the deformation is completed, cool and set at near room temperature, and then demold and form.

[0061] In this solution, the materials of the polymer shell 100 are taken as PPSU and PC for example. The secondary forming temperature of PPSU is 220 - 280 °C, and the secondary forming temperature of PC is 130 - 200 °C.

[0062] Preferably, when performing secondary forming, it is necessary to control the water content of the shell polymer 100 to avoid excessive water content resulting in the generation of bubbles.

[0063] Among them, Tb is the brittle temperature; Tg is the glass transition temperature.

[0064] S220. Shape the outer wall of the shell blank in the high elastic state. Through the forming die acting on the outer wall of the corresponding end of the shell blank, shape it into the outer shape of the front end 120.

[0065] When one end of the shell blank without the metal base 200 is heated and enters the high elastic state, apply a force to the shell blank, so that the part entering the high elastic state is gradually pressed into the cavity of the forming die until the shell blank moves a set distance.

[0066] See the appendix Figure 6 As shown, in the appendix Figure 6 the structural schematic diagram of the forming die is given.

[0067] Among them, d is the die, e is the secondary forming cavity, f is the heating area on the die, g is the shaping pull rod, and h is the pushing protrusion on the shaping pull rod.

[0068] Among them, the direction of the force applied to the shell blank is the direction indicated by the arrow F.

[0069] When the shell blank is moved into the forming die, with the force and after the corresponding position enters the high elastic state, the shell blank will be gradually pushed into the forming die, and under the extrusion effect, the outer shaping of the front end 120 is completed.

[0070] At this time, due to the extrusion effect, the wall thickness at the front end 120 exceeds the set value and needs further shaping.

[0071] S230. Shape the inner wall of the shell blank in the high elastic state. Shape the inner wall at the front end 120 through the shaping pull rod extending into the shell blank.

[0072] The shaping pull rod extends into the rough shell blank before the rough shell blank enters the high elastic state and cooperates with the cavity of the forming die to shape the front end 120. That is, before the rough shell blank extends into the forming die, the end of the shaping pull rod enters the rough shell blank. Since the port of the rough shell blank has not shrunk at this time, it is easier for the shaping pull rod to extend into the rough shell blank.

[0073] After the rough shell blank extends into the die to a specified distance, the outer shape of the front end 120 is completed. At this time, pull the shaping pull rod along the direction of arrow F, and use the material pushing convex part on the shaping pull rod to shape the inner wall of the front end 120, so that the inner wall reaches the set thickness under the extrusion of the material pushing convex. Then the shell can be taken out to obtain the refined shell blank.

[0074] The refined shell blank means that both the rear end 110 and the front end 120 have been formed, and the inner and outer walls of the front end 120 have been shaped, and there is only excess material at the mouth of the front end 120.

[0075] Trim the refined shell blank obtained in S200. If it passes the inspection, the finished product can be obtained.

[0076] That is, just cut off the excess material at the mouth of the front end 120 to ensure the regular size of the shell.

[0077] The above manufacturing method adopts the insert injection molding process, the secondary thermoforming process and the extrusion process, which optimizes the problems of large weight and metal resource consumption of the traditional metal shell for the polymer shell 100. And the whole process does not use glue bonding, with lower cost and higher product quality.

[0078] In addition, using the polymer shell 100 can also eliminate the step difference between the metal base 200 and the shell, improve the sealing performance, density and consistency during shooting, and because the whole outer surface of the shell is made of polymer material with lower hardness, it can greatly reduce the wear of the gun chamber and improve the barrel life.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it.

Claims

1. A cartridge case, characterized in that, Comprising: A polymer cartridge case (100) and a metal base (200); The polymer cartridge case (100) includes an integrally formed rear end (110) and a front end (120). An inclination is provided on the inner wall corresponding to the rear end (110), and the direction of the inclination is from the rear end (110) towards the front end (120). The wall thickness of the rear end (110) gradually decreases, and reaches the minimum value at the junction of the rear end (110) and the front end (120); The metal base (200) is fixed to the port of the rear end (110) by insert injection molding; The front end (120) is adapted to the bullet; 2. A cartridge case according to claim 1, characterized in that: The rear end (110) is cylindrical, and the outer wall of the port of the rear end (110) has a concavo-convex structure (130). The concavo-convex structure (130) extends into the metal base (200) and meshes with the inner wall of the metal base (200); 3. A cartridge case according to claim 1, characterized in that: The material of the polymer cartridge case (100) is a high molecular polymer material; 4. A processing technology for a cartridge case, used for manufacturing the cartridge case according to any one of claims 1-3, characterized in that, Including the following steps: S100. Adopt the insert injection molding process to integrally injection mold the metal base (200) and the polymer cartridge case (100), so that the rear end (110) is formed to obtain a rough cartridge case blank; S200. Perform secondary thermoforming on the cartridge case blank obtained in S100, so that the front end (120) is formed to obtain a refined cartridge case blank; S300. Trim the refined cartridge case blank obtained in S200, and obtain the finished product after passing the inspection; 5. A processing technology of a cartridge case according to claim 4, characterized in that: In S100, the rough cartridge case blank is a cylindrical structure with one end open; 6. A processing technology of a cartridge case according to claim 4, characterized in that: In S200, the method of the secondary thermoforming includes the following steps: S210. Place the rough cartridge case blank into the heated forming mold, so that the rough cartridge case blank is heated to enter the highly elastic state; S220. Shape the outer wall of the rough cartridge case blank in the highly elastic state. Through the action of the forming mold on the outer wall of the corresponding end of the rough cartridge case blank, shape it into the outer shape of the front end (120); S230. Shape the inner wall of the rough cartridge case blank in the highly elastic state. Shape the inner wall at the front end (120) through a shaping pull rod extending into the rough cartridge case blank; 7. A processing technology of a cartridge case according to claim 6, characterized in that: In S220, when one end of the rough cartridge case blank without the metal base (200) is heated to enter the highly elastic state, apply a force to the rough cartridge case blank, so that the part entering the highly elastic state is gradually pressed into the cavity of the forming mold until the rough cartridge case blank moves a set distance; 8. A processing technology of a cartridge case according to claim 6, characterized in that: In S230, the shaping pull rod extends into the rough cartridge case blank before the rough cartridge case blank enters the highly elastic state, and cooperates with the cavity of the forming mold to realize the shaping of the front end (120).

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