Solid engine 3d printing grain isostatic pressing densification forming method

Abstract

The application relates to a solid engine grain isostatic pressing and compacting device and method, which comprises the following steps: firstly, obtaining a pre-solidified high-solid-content special-shaped grain; then, assembling a matched supporting tool according to the grain shape; then, loading the grain with the supporting tool into a wall tool and moving into an engine shell; covering a diaphragm with a certain strength and elongation on the inner hole surface of the grain, and passing a liquid with a specific temperature into the lowest part of the diaphragm cavity to discharge the air between the diaphragm and the grain, so that the diaphragm is tightly attached to the inner wall surface of the grain; installing a top cover to ensure that the diaphragm edge exceeds a sealing ring, so that the grain is completely separated from the liquid; finally, connecting a hydraulic pump through a pressure measuring connector to gradually increase the cavity pressure in stages, so that the pressure solidification and heat solidification are realized. The application can realize high compacting of 3D printing solid grains with multiple burning rates and complex grain shapes, and fundamentally solves the problems of structural integrity and combustion caused by the low compacting density of 3D printing high-solid-content solid grains.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid rocket engine, and relates to a solid engine 3D printing grain isostatic pressing densification forming method. BACKGROUND

[0002] Solid propellant is the main structural component and energy material of missile system, and its energy level and structural integrity determine the range and working reliability of missile weapon. The current solid engine charge is formed by casting, and the grain shape depends on the core mold shape. Limited by the demolding process, the current charge usually adopts relatively simple circular tube or star structure, which cannot realize complex structure charge forming, and then it is difficult to realize the diversification of solid engine interior trajectory. The use of 3D printing technology can break through the constraints of existing charge technology and realize the printing forming of solid grain with multiple burning rates and complex structures. However, due to the limitations of printing process and high viscosity propellant slurry, the propellant is difficult to realize densification forming through its own flow and gravity. Therefore, the research on the high densification forming method of 3D printing solid grain plays an important role in promoting the application of 3D printing technology in solid propellant. SUMMARY

[0003] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a solid engine 3D printing grain isostatic pressing densification forming method, which realizes high densification forming of multiple burning rate and complex structure charge and fundamentally solves the problems of structural integrity and combustion caused by the low densification of 3D printing high solid content solid grain due to the existence of many pores.

[0004] The technical solution of the present application is: a solid engine grain isostatic pressing densification forming device, which comprises a support tool, a wall tool, a diaphragm, a top cover, a pressure measuring connector, a hydraulic pump, an engine shell and a base;

[0005] The engine shell is fixedly connected with the base at one end and fixedly connected with the top cover at the other end, forming a hollow cavity structure.

[0006] The wall tool is a hollow cylindrical structure and closely adheres to the inner wall of the engine shell.

[0007] The support tool is used for supporting the to-be-solidified and formed special-shaped grain and is located in the wall tool together with the to-be-solidified and formed special-shaped grain.

[0008] The diaphragm is arranged between the top cover and the engine shell and covers the inner hole surface of the to-be-solidified and formed special-shaped grain and closely adheres to the surface of the grain. A through hole is arranged in the middle of the top cover, and the pressure measuring connector is connected to the through hole and connected with the hydraulic pump. The pressure measuring connector introduces the pressurized medium in the hydraulic pump into the diaphragm, discharges the air between the diaphragm and the grain, and pressurizes and forms the to-be-solidified and formed special-shaped grain.

[0009] Preferably, the diaphragm is selected from rubber materials with a thickness of 0.5mm-4mm.

[0010] Preferably, the shaped irregular propellant to be solidified is a 3D printed propellant with a solid content of more than 90%.

[0011] Preferably, a sealing ring is arranged between the top cover and the engine shell, the diaphragm is located close to the end face of the engine shell, the sealing ring is pressed on the diaphragm, and the top cover is pressed on the sealing ring.

[0012] Preferably, the medium pressure is in the range of 10-50MPa, and the pressure maintaining time is generally not less than 2h.

[0013] Preferably, the temperature of the pressurized medium is not more than 70℃, and the temperature variation range is not more than 5℃.

[0014] Another technical scheme of the present application is a solid engine propellant isostatic pressing densification forming method, which comprises the following steps:

[0015] S1, assembling the shaped irregular propellant to be solidified and the supporting tooling in place to keep the shaped irregular propellant to be solidified in a vertical state;

[0016] S2, placing the shaped irregular propellant to be solidified and the supporting tooling on the base and loading the wall tooling;

[0017] S3, loading the assembly obtained in step s2 into the engine shell;

[0018] S4, covering the diaphragm on the inner hole surface of the propellant and tightly adhering the diaphragm to the propellant surface, adding a pressurized medium at a certain temperature to the diaphragm, and discharging the air between the diaphragm and the propellant;

[0019] S5, sealingly connecting the top cover with the engine shell, connecting the hydraulic pump through the pressure measuring connector, and gradually increasing the medium pressure in stages, and maintaining the pressure for a certain time under each pressure condition.

[0020] Preferably, the pressurized medium is water or oil.

[0021] Preferably, the medium pressure is in the range of 10-50MPa, and the pressure maintaining time is generally not less than 2h.

[0022] Preferably, the temperature of the pressurized medium is not more than 70℃, and the temperature variation range is not more than 5℃.

[0023] The present application has the following beneficial effects compared with the prior art:

[0024] (1) high solid content solid propellant densification forming can be realized, high solid content propellant is an important way to improve the specific impulse of material density, which can effectively improve the energy performance of the solid engine;

[0025] (2) can obtain high filling, low stress shaped charge configuration. Based on 3D printing technology can realize high solid content propellant different burning rate, different charge forming of grain structure, based on the application, will solve the problem of dense forming, make 3D printing high filling, low stress charge configuration become possible. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 For the solid rocket engine 3D printing solid grain isostatic compaction schematic diagram.

[0027] Wherein, 1-measuring pressure connector, 2-cap, 3-engine shell, 4-wall tooling, 5-6 solid grain, 7-support tooling, 8-septum, 9-pressurizing medium. DETAILED DESCRIPTION

[0028] The application will be further described below in conjunction with examples.

[0029] The application will be further described below in conjunction with examples.

[0030] The application provides a solid rocket engine grain isostatic compaction device, which comprises support tooling 7, wall tooling 4, septum 8, cap 2, pressure measuring connector 1, hydraulic pump, engine shell 3 and base;

[0031] The engine shell 3 is fixedly connected to the base at one end and fixedly connected to the cap 2 at the other end, forming a hollow cavity structure.

[0032] The wall tooling 4 is a hollow columnar structure and closely adheres to the inner wall of the engine shell 3.

[0033] The support tooling 7 is used for supporting the shaped grain to be solidified and formed and is located in the wall tooling 4 together with the shaped grain to be solidified and formed.

[0034] The cap 2 is provided with the septum 8 opening upward between the cap 2 and the engine shell 3, the septum 8 covers the inner hole surface of the shaped grain to be solidified and formed and closely adheres to the surface of the grain, the cap 2 is provided with a through hole in the middle, the pressure measuring connector 1 is connected to the through hole, and the pressure measuring connector 1 is connected to the hydraulic pump; the pressure measuring connector 1 introduces the pressurizing medium in the hydraulic pump into the septum 8, discharges the air between the septum and the grain, and pressurizes the shaped grain to be solidified and formed.

[0035] Preferably, the septum is made of a material with large elongation and certain strength, including but not limited to rubber material, and the thickness is generally 0.5mm-4mm.

[0036] Preferably, the to-be-solidified shaped irregular grain is a 3D printed grain, and the solid content of the grain is more than 90%.

[0037] Preferably, a sealing ring is arranged between the top cover 2 and the engine shell 3, the diaphragm 8 is located close to the end surface of the engine shell 3, the sealing ring is pressed on the diaphragm 8, and the top cover 2 is pressed on the sealing ring.

[0038] Preferably, the medium pressure is in a range of 10-50 MPa, and the pressure maintaining time is generally not less than 2 h.

[0039] Preferably, the temperature of the pressurized medium is not more than 70 DEG C, and the temperature variation range is not more than 5 DEG C.

[0040] Based on the above device, the application further provides a solid engine grain isostatic pressing densification forming method, which comprises the following steps:

[0041] S1, assembling the to-be-solidified shaped irregular grain and the supporting tool 7 in place, so that the to-be-solidified shaped irregular grain is kept in a vertical state;

[0042] S2, placing the to-be-solidified shaped irregular grain and the supporting tool 7 on the base and loading the wall tool 4;

[0043] S3, loading the assembly obtained in step s2 into the engine shell 3;

[0044] S4, covering the diaphragm 8 on the inner hole surface of the grain and tightly adhering the diaphragm 8 to the surface of the grain, adding the pressurized medium 9 of a certain temperature to the diaphragm, and discharging the air between the diaphragm and the grain;

[0045] S5, sealingly connecting the top cover 2 and the engine shell 3, connecting the hydraulic pump through the pressure measuring connector 1, and gradually increasing the medium pressure in stages, and maintaining the pressure for a certain time under each pressure level.

[0046] Preferably, the pressurized medium 9 is water or oil.

[0047] Preferably, the medium pressure is in a range of 10-50 MPa, and the pressure maintaining time is generally not less than 2 h.

[0048] Preferably, the temperature of the pressurized medium is not more than 70 DEG C, and the temperature variation range is not more than 5 DEG C.

[0049] Embodiment:

[0050] In order to improve the forming efficiency, a plurality of to-be-solidified shaped irregular grains with the same diameter and communicated inner holes and different lengths can be spliced together for forming. Figure 1 As shown in the embodiment,

[0051] The solid engine 3D printing grain column isostatic pressing densification forming process comprises a pressure measuring connector 1, a top cover 2, an engine shell 3, a wall tool 4, a support tool 7, a diaphragm 8, a pressurizing medium 9 and the like.

[0052] In order to achieve the above purpose, the present application provides a solid engine 3D printing grain column isostatic pressing densification forming method, comprising the following steps:

[0053] A. Based on the interior ballistic design of the solid engine, an ideal grain shape (the ideal grain shape can be a multi-burning rate complex configuration) is obtained. The corresponding solid grain column is obtained through a 3D printing forming process. In the embodiment, two grain columns are obtained, which are a first solid grain column 5 and a second solid grain column 6. The solid content of the first solid grain column 5 and the second solid grain column 6 is high and the configuration is arbitrary, the burning rate is arbitrary, but the diameters are the same.

[0054] B. The second solid grain column 6 obtained through 3D printing is assembled in place with the support tool, the first solid grain column 5 is placed above the second solid grain column 6, and the inner holes of the first solid grain column 5 and the second solid grain column 6 are connected. The support tool 7 needs to be adaptively adjusted according to the configuration of the printed grain column.

[0055] C. The special-shaped grain column is assembled into the wall tool in cooperation with the support tool and is axially positioned.

[0056] D. The assembly assembly described in C is assembled into the engine shell.

[0057] The size of the support tool 7, the wall tool 4 and the engine shell 3 can be arbitrary and is adaptively adjusted according to the design needs of the grain column.

[0058] E. The diaphragm is covered on the inner hole surface of the grain column and is tightly attached to the surface of the grain column. A pressurizing medium (water or oil) at a certain temperature is added to the diaphragm, and the air between the diaphragm and the grain column is discharged.

[0059] F. The top cover is installed, the edge of the diaphragm is ensured to pass through the sealing ring, so as to ensure that the pressurizing medium does not contaminate the printed grain column. The hydraulic pump is connected through the pressure measuring connector, the medium pressure is gradually increased in stages, and the pressure is maintained for a certain time as needed.

[0060] The temperature of the pressurizing medium is not more than 70 DEG C. If necessary, it can be cyclically treated to ensure that the temperature is relatively constant. In the embodiment, it is 58 DEG C. to 62 DEG C. At the same time, the entire engine can be heat preserved to realize pressurizing solidification and heat curing.

[0061] The pressure of the isostatic pressing is adjusted according to the size of the engine grain column. The pressure range is 10-50 MPa, and the pressure maintaining time is generally not less than 2 h. According to experience, the pressure of the large size is given a little larger, and the pressure of the small size is given a little smaller.

[0062] According to the above method, the isostatic pressing densification of the 95% solid content 3D printed solid propellant column has been completed in this embodiment, and CT detection has been completed. The test results show that the internal propellant column is dense and defect-free.

[0063] Although the present application has been disclosed with reference to the preferred embodiments, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the present application by using the disclosed methods and technical contents without departing from the spirit and scope of the present application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solutions of the present application, belongs to the protection scope of the technical solutions of the present application.

Claims

1. An isostatic pressing densification apparatus for solid propellant grains in a solid engine, characterized in that... Includes support fixture (7), wall fixture (4), diaphragm (8), top cover (2), pressure test nozzle (1), hydraulic pump, engine housing (3), and base; One end of the engine housing (3) is fixedly connected to the base, and the other end is fixedly connected to the top cover (2), forming a hollow cavity structure; The wall fixture (4) is a hollow columnar structure that fits tightly against the inner wall of the engine housing (3); Support fixture (7) is used to support the irregularly shaped propellant column to be cured and is located in the wall fixture (4) together with the irregularly shaped propellant column to be cured and formed. A diaphragm (8) with an upward opening is provided between the top cover (2) and the engine housing (3). The diaphragm (8) covers the inner surface of the irregularly shaped propellant column to be cured and fits tightly against the surface of the propellant column. A through hole is provided in the middle of the top cover (2), and a pressure testing nozzle (1) is connected to the through hole. The pressure testing nozzle (1) is connected to a hydraulic pump. The pressure testing nozzle (1) introduces the pressurizing medium in the hydraulic pump into the diaphragm (8), discharges the air between the diaphragm and the propellant column, and pressurizes the irregularly shaped propellant column to be cured. The irregularly shaped propellant column to be cured and molded has a complex configuration with multiple burning rates; the irregularly shaped propellant column to be cured and molded is a 3D printed propellant column with a solid content of over 90%.

2. The isostatic pressing densification apparatus for solid propellant grains according to claim 1, characterized in that... The diaphragm is made of rubber and has a thickness of 0.5 mm to 4 mm.

3. The isostatic pressing densification apparatus for solid propellant grains according to claim 1, characterized in that: A sealing ring is provided between the top cover (2) and the engine housing (3). The diaphragm (8) is located close to the end face of the engine housing (3). The sealing ring is pressed on the diaphragm (8), and the top cover (2) is pressed on the sealing ring.

4. The isostatic pressing densification apparatus for solid propellant grains according to claim 1, characterized in that, The pressure range of the pressurizing medium (9) is 10-50 MPa, and the pressure holding time is generally not less than 2 hours.

5. The isostatic pressing densification apparatus for solid propellant grains according to claim 1, characterized in that, The temperature of the pressurizing medium (9) does not exceed 70°C and the temperature variation range does not exceed 5°C.

6. A method for isostatic compaction of solid propellant grains for a solid propellant engine based on the apparatus of claim 1, characterized in that... Includes the following steps: S1. Assemble the irregularly shaped drug column to be cured and molded with the support fixture (7) in place, so that the irregularly shaped drug column to be cured and molded remains vertical. S2. Place the irregularly shaped drug column to be cured and the support fixture (7) on the base, and install the wall fixture (4); S3. Install the assembly components obtained in step s2 into the engine housing (3); S4. Cover the inner surface of the drug column with the diaphragm (8) and make it fit tightly against the surface of the drug column. Add a pressurizing medium (9) at a certain temperature to the diaphragm and expel the air between the diaphragm and the drug column. S5. Seal the top cover (2) and the engine housing (3) together. Connect the hydraulic pump through the pressure test port (1) and gradually increase the medium pressure in stages. Under each pressure condition, maintain the pressure for a certain period of time.

7. The method for isostatic compaction of solid propellant grains in a solid rocket motor according to claim 6, characterized in that, The pressurizing medium (9) is water or oil.

8. The method for isostatic compaction of solid propellant grains in a solid rocket motor according to claim 6, characterized in that, The pressure range of the pressurizing medium (9) is 10-50 MPa, and the pressure holding time is generally not less than 2 hours.

9. The method for isostatic compaction of solid propellant grains in a solid rocket motor according to claim 6, characterized in that, The temperature of the pressurizing medium (9) does not exceed 70°C and the temperature variation range does not exceed 5°C.

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