A method for forming a shaped charge with a stepped gasket by die molding and a formed charge

Abstract

A kind of stage-by-stage extraction gasket moulding method of special PBX explosive and formed propellant grain, comprising the following steps: PBX modeling powder is added to the mold cylinder, pre-pressing is carried out, and initial compaction body is formed;After pre-pressing is completed, first extraction gasket operation is carried out;Continue to press and enter the pressure maintaining stage, and second extraction gasket operation is carried out in the pressure maintaining process;After pressure maintaining is finished, demoulding is obtained, and formed propellant grain is obtained.The present application controls the densification behavior of PBX modeling powder in the process of moulding by stage-by-stage extraction gasket, avoids local excessive densification, improves the density uniformity of propellant grain, reduces internal defects, and significantly shortens the pressure maintaining time, improves production efficiency.

Description

Technical Field

[0001] This invention belongs to the field of mixed explosive molding technology, and relates to a staged gasket compression molding method for irregular PBX explosives and the molding explosive charge. Background Technology

[0002] PBX (Polymer Bonded Explosive) is typically composed of high-energy particles and polymer binders, belonging to a typical high-filler particle composite system. During its compression molding process, the densification behavior of the PBX explosive directly affects the mechanical properties, safety performance, and reliability of the product, while the holding time during compression molding directly impacts production efficiency. For irregularly shaped PBX explosives, due to their complex geometry and uneven thickness distribution, the following problems are prone to occur during compression molding: ① Uneven pressure transmission in different areas leads to uneven density distribution; ② Premature densification in localized areas results in a "lock-in" phenomenon, making it difficult for internal gas to escape in time, easily forming pores or defects; ③ Difficulty in rapidly improving molding density and quality leads to excessively long holding times.

[0003] In existing processes, a shim removal operation (e.g., removing a 5mm shim at once) is typically performed at the beginning of the pressure holding stage to improve the overall compaction. While this method can improve the explosive forming density to some extent, it still has the following drawbacks: ① A single large-scale compression can easily lead to premature densification in localized areas; ② Subsequent material flow is restricted, making redistribution difficult; ③ Density gradients are easily formed, affecting product consistency; ④ The pressure holding time is relatively long, resulting in low production efficiency. Summary of the Invention

[0004] In view of the defects and deficiencies in the existing technology, the present invention aims to provide a staged gasket compression molding method for irregular PBX explosives and a molding explosive charge, so as to improve the densification path, improve density uniformity, and shorten the holding time.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0006] A staged shim removal molding method for irregularly shaped PBX explosives includes the following steps: Step 1: Add PBX molding powder into the mold cylinder and pre-press it to form an initial compacted body; Step 2: After pre-pressing, perform the first shim removal operation to allow the punch to move downwards; Step 3: Continue pressurizing and enter the pressure holding stage. During the pressure holding process, perform the second shim removal operation to allow the punch to move further downwards; Step 4: After the pressure holding is completed, demold to obtain the molded explosive charge.

[0007] Preferably, the thickness of the first gasket is greater than the thickness of the second gasket.

[0008] Preferably, the thickness of the first gasket is 60%-90% of the total gasket thickness.

[0009] Preferably, the pre-compression pressure is 70%-90% of the maximum compression pressure.

[0010] Preferably, the first gasket extraction operation is performed after pre-compression is completed and before re-compression is applied, by depressurizing and then extracting the gasket.

[0011] Preferably, the second gasket extraction operation is performed during the pressure holding stage, after the molding powder has flowed and the pressure is released before extraction, and then pressure holding is performed again after extraction.

[0012] Preferably, the total thickness of the gasket is 4-6mm.

[0013] Preferably, the first and second shim removal operations are achieved by replacing or removing the shims set in the mold.

[0014] A shaped drug column is prepared by the method disclosed in this application.

[0015] The above technical solution has the following beneficial effects: (1) Improve the densification path: By removing pads in stages, the molding powder gradually changes from the initial accumulation state to a uniform and dense state, avoiding local over-densification caused by a single loading.

[0016] (2) Improve density uniformity: The second padding can break the local dense "locked" state, promote the redistribution of the molding powder, and thus significantly reduce the density gradient.

[0017] (3) Reduce internal defects: It is beneficial for gas to be discharged, reduces porosity, and increases the internal density of the propellant column.

[0018] (4) Shorten the holding time: Due to the improved densification efficiency, the target density can be achieved in a shorter holding time, thereby improving production efficiency.

[0019] (5) Applicable to irregular structures: It has better adaptability to areas with uneven thickness, and is especially suitable for complex PBX explosives. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the mold used in the method of the embodiment.

[0021] The numbers in the diagram are: 0. Propellant cartridge, 1. Punch, 2. Guide cylinder, 3. Die cylinder, 4. Gasket, 5. Support block, 6. Base. Detailed Implementation The present invention will be described in further detail below with reference to specific embodiments, but the implementation of the present invention includes, but is not limited to, the scope represented by the following embodiments.

[0022] Figure 1 The diagram shows the structure of the mold used in this application. The mechanical implementation of "extracting the gasket 5" is a well-known operation to those skilled in the art and will not be described in detail here.

[0023] Example 1 In this embodiment, there are two gaskets 4, with thicknesses of 3mm and 2mm respectively.

[0024] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 50.6 mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 3mm gasket; d) Maintain pressure at 250 MPa for 30 minutes; e) Depressurize and then remove the 2mm gasket; f) Maintain pressure at 250 MPa for 23 minutes; g) Unload and demold.

[0025] The molding density of the molded propellant column obtained in this embodiment is 1.797 g / cm³. 3 The molding quality is flawless.

[0026] Example 2 In this embodiment, there are two gaskets 4, with thicknesses of 4mm and 1mm respectively.

[0027] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 50.6 mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 4mm gasket; d) Maintain pressure at 250 MPa for 30 minutes; e) Depressurize and then remove a 1mm gasket; f) Maintain pressure at 250 MPa for 18 minutes; g) Unload and demold.

[0028] The molding density of the molded propellant column obtained in this embodiment is 1.832 g / cm³. 3 The molding quality is flawless.

[0029] Example 3 In this embodiment, there is one gasket 4, which is 5mm thick.

[0030] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 50.6 mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 5mm gasket; d) Maintain pressure at 250 MPa for 60 minutes; g) Unload and demold.

[0031] The molding density of the molded propellant column obtained in this embodiment is 1.830 g / cm³. 3 The molding quality was flawless, but the holding time was significantly longer than that of Examples 1 and 2.

[0032] Example 4 In this embodiment, there are two gaskets 4, with thicknesses of 4mm and 1mm respectively.

[0033] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 50.6 mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 4mm gasket; d) Maintain pressure at 250 MPa for 30 minutes; e) Depressurize and then remove a 1mm gasket; f) Maintain pressure at 250 MPa for 17 minutes; g) Unload and demold.

[0034] The molding density of the molded propellant column obtained in this embodiment is 1.798 g / cm³. 3 The molding quality has minor cracks.

[0035] Example 5 In this embodiment, there are two gaskets 4, with thicknesses of 3mm and 2mm respectively.

[0036] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 86mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 3mm gasket; d) Maintain pressure at 250 MPa for 40 minutes; e) Depressurize and then remove the 2mm gasket; f) Maintain pressure at 250 MPa for 30 minutes; g) Unload and demold.

[0037] The molding density of the molded propellant column obtained in this embodiment is 1.793 g / cm³. 3 The molding quality is flawless.

[0038] Example 6 In this embodiment, there are two gaskets 4, with thicknesses of 4mm and 1mm respectively.

[0039] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 86mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 4mm gasket; d) Maintain pressure at 250 MPa for 40 minutes; e) Depressurize and then remove a 1mm gasket; f) Maintain pressure at 250 MPa for 24 minutes; g) Unload and demold.

[0040] The molding density of the molded propellant column obtained in this embodiment is 1.799 g / cm³. 3 The molding quality is flawless.

[0041] Example 7 In this embodiment, there is one gasket 4, which is 5mm thick.

[0042] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 86mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 5mm gasket; d) Maintain pressure at 250 MPa for 80 minutes; e) Unload and demold.

[0043] The molding density of the molded propellant column obtained in this embodiment is 1.796 g / cm³. 3 The molding quality is flawless.

[0044] Example 8 In this embodiment, there are two gaskets 4, with thicknesses of 4mm and 1mm respectively.

[0045] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 86mm; b) Preload with a pressure of 200 MPa for 20 seconds; c) Depressurize and then remove the 4mm gasket; d) Maintain pressure at 250 MPa for 40 minutes; e) Depressurize and then remove a 1mm gasket; f) Maintain pressure at 250 MPa for 22 minutes; g) Unload and demold.

[0046] The molding density of the molded propellant column obtained in this embodiment is 1.795 g / cm³. 3 The molding quality has minor cracks.

[0047] Example 9 This embodiment does not involve removing the gasket; it directly presses the material to the maximum pressure in one go and holds the pressure.

[0048] a) Add PBX molding powder into the irregular mold cylinder with a maximum diameter of 86mm; b) Maintain pressure at 250 MPa for 80 minutes; c) Unload and demold.

[0049] The molding density of the molded propellant column obtained in this embodiment is 1.782 g / cm³. 3 The molding quality is flawless.

[0050] Table 1 compares the results of Examples 1 to 9. The results show that Example 2 (4mm+1mm combination) has the highest density, shortest holding time, and no defects in the mold with a maximum diameter of 50.6mm; Example 6 (4mm+1mm combination) performs best in the 86mm mold.

[0051]

[0052] Any modifications, equivalent substitutions, improvements, or other solutions made within the principles of this invention that do not depart from the technical scope of this invention, and are applied to any field, constitute an infringement of the protection scope of this invention and are included within the protection scope of this invention.

Claims

1. A method for staged gasket molding of irregularly shaped PBX explosives, characterized in that, Includes the following steps: Step 1: Add PBX molding powder into the mold cylinder and pre-press it to form an initial pressed body. Step 2: After pre-compression is completed, perform the first shim removal operation to allow the punch to move downwards; Step 3: Continue to pressurize and enter the pressure holding stage. During the pressure holding process, perform a second shim removal operation to move the punch further downward. Step 4: After the pressure holding period is over, demold to obtain the molded drug cartridge.

2. The method for staged gasket molding of irregularly shaped PBX explosives according to claim 1, characterized in that, The thickness of the first gasket is greater than the thickness of the second gasket.

3. The method for staged gasket molding of irregularly shaped PBX explosives according to claim 2, characterized in that, The thickness of the first shim is 60%-90% of the total shim thickness.

4. The method for staged gasket molding of irregularly shaped PBX explosives according to claim 1, characterized in that, The pre-compression pressure is 70%-90% of the maximum compressive pressure.

5. The method for staged gasket compression molding of irregularly shaped PBX explosives according to claim 1, characterized in that, The first gasket extraction operation is performed after depressurization is completed and before repressurization is applied, by depressurizing the gasket.

6. The method for staged gasket molding of irregularly shaped PBX explosives according to claim 1, characterized in that, The second gasket extraction operation is performed during the pressure holding stage. After the molding powder flows, the pressure is released and the gasket is extracted. After extraction, the pressure is held again.

7. The method for staged gasket compression molding of irregularly shaped PBX explosives according to claim 1, characterized in that, The total thickness of the gasket is 4-6mm.

8. The method for staged gasket compression molding of irregularly shaped PBX explosives according to claim 1, characterized in that, The first and second gasket removal operations are achieved by replacing or removing the gaskets set in the mold.

9. A molded drug cartridge, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

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