A method of manufacturing a single head engine composite shell

Abstract

The present application belongs to the technical field of composite material forming process, and particularly relates to a preparation method of a single-seal-head composite material engine shell. In the preparation of the single-seal-head composite material engine shell, an arc-shaped false seal head is used in the straight cylinder section, and a hanging nail with an arrangement rule meeting the winding angle requirement is prefabricated at the connection between the rear connecting piece and the composite material layer, so that the fiber strength play rate is improved, the shell strength requirement under the condition of a specific thickness is met, the stability and accurate arrangement of the winding line type are ensured, fiber accumulation is avoided, the production efficiency is greatly improved, and the size stability of the shell is ensured. In addition, the use of the false seal head of the present application ensures the winding line type design and realizes geodesic winding.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding technology, specifically relating to a method for preparing a composite material casing for a single-head engine. Background Technology

[0002] A solid rocket motor is the power plant for rockets or missiles, consisting of four parts: a combustion chamber, propellant grains, a nozzle, and an igniter. The combustion chamber serves as both a solid propellant storage chamber and a propellant combustion chamber. The winding process for rocket motor casings differs from that of conventional cylindrical casings because solid rocket motor casings are typically semi-enclosed or cylindrical structures with tapered ends. This design inherently presents challenges in molding and design.

[0003] Generally, solid engine casings typically have end caps at both ends, allowing designers to create a winding profile based on the polar hole size. However, this design method is not suitable for single-end-cap composite engine casings because theoretical calculations and process adjustments make it difficult to guarantee that the end without end caps meets the internal pressure requirements. Currently, there are no reports on design methods for single-end-cap composite engine casings. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing composite material housings for single-head engines, which can both ensure the required shape of the winding process and meet the internal pressure requirements of the engine housing.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: by designing an arc-shaped false head in the straight section of the composite material shell of the single-head engine, and prefabricating hanging pins with a layout pattern that meets the requirements of the winding angle at the connection between the rear connector and the composite material layer, the shell strength requirements under specific thickness conditions are met, the stability of the winding line is ensured, fiber accumulation is avoided, production efficiency is greatly improved, and the shell dimensional stability is ensured, thus achieving the purpose of the present invention.

[0006] This invention relates to a method for preparing a composite material casing for a single-head engine. The composite material casing for the single-head engine includes a skirt, a front arc-shaped contraction section, and a rear straight section. The arc-shaped contraction section includes, from the inside out, an insulation layer, a front connector, and a composite material layer. The straight section includes an inner insulation layer, an outer composite material layer, and a rear connector, with the front section of the rear connector located between the insulation layer and the composite material layer. The skirt is located outside the arc-shaped contraction section, and its rear end is located inside the composite material layer. The method is characterized by the following preparation steps:

[0007] 1) Calculate the winding angle of the arc-shaped contraction section of the single-head composite material shell;

[0008] 2) The arrangement of the hanging pins on the outer surface of the front end of the connector is designed according to the winding angle; the angle β between the line connecting the adjacent hanging pins in each row and the center of the circle is 6°~9°, and the angle between the vertical arrangement direction and the vertical direction is the winding angle ±3°.

[0009] 3) Prepare a mold, including a mandrel, a skirt fixing device, a front connector fixing device, a dummy end cap, and a dummy end cap fixing device; the mandrel includes a large cylinder in the middle and small cylinders at the front and rear ends, used to form the composite material shell, and to fix the skirt fixing device, the front connector fixing device, and the dummy end cap fixing device; the dummy end cap has a front section for fixing the rear connector and a rear section with an arc-shaped contraction structure; the skirt fixing device, the front connector fixing device, and the dummy end cap fixing device are used to fix the skirt, the front connector, and the dummy end cap, respectively;

[0010] 4) Fix the mandrel and lay an insulating layer on the outside of its large cylinder; at the front end of the mandrel, put the front connector on the small cylinder, fit it with the laid insulation layer, and fix its position using the front connector fixing device; at the rear end of the mandrel, place the front part of the rear connector on the outside of the insulation layer, and then put the dummy end cap on the small cylinder, and fix the position of the dummy end cap using the dummy end cap fixing device.

[0011] 5) Wrap the composite material layer on the outer surface of the front connector, the insulation layer and the front section of the rear connector at the calculated winding angle; after the composite material layer is wound to the designed thickness, place the skirt and fix its position using the skirt fixing device; continue to wrap the composite material layer on the outside until the preset thickness is reached;

[0012] 6) After winding, cure using a curing process;

[0013] 7) After curing, remove the mold to complete the preparation of the composite material shell for the single-head engine.

[0014] Preferably, the angle β between the line connecting adjacent nails in each row and the center of the circle is 7.5°, and the angle between the vertical arrangement direction and the vertical direction is the winding angle.

[0015] Preferably, the skirt fixing device includes a skirt positioning block locking nut (2) and a skirt positioning block (3).

[0016] Preferably, the front connector fixing device includes a front connector locking nut (4).

[0017] Preferably, the front connector fixing device further includes a pad (5).

[0018] Preferably, the dummy end cap fixing device is a locking nut (11).

[0019] Preferably, the small cylinder at the front end of the mandrel (1) has two steps that increase in size from front to back; the small cylinder at the rear end has two steps that decrease in size from front to back.

[0020] This invention improves fiber strength utilization and meets shell strength requirements under specific thickness conditions by employing an arc-shaped dummy head in the straight section and prefabricating hooks with a regular arrangement to meet winding angle requirements at the connection between the rear connector and the composite material layer. This ensures stable and accurate winding pattern arrangement, avoids fiber accumulation, significantly improves production efficiency, and guarantees shell dimensional stability. Furthermore, the use of the dummy head ensures the winding pattern design and achieves geodesic winding. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the assembly of the engine composite material housing and mold of the present invention;

[0022] Figure 2 This is a cross-sectional view of the skirt of the present invention;

[0023] Figure 3 This is a schematic diagram showing the positions of the hanging nails in the same row as the rear connector of the present invention;

[0024] Figure 4 This is a schematic diagram of the rear connector structure of the present invention;

[0025] Figure 5 This is a schematic diagram of the mandrel structure of the present invention;

[0026] Figure 6 This is a cross-sectional view of the skirt positioning block of the present invention.

[0027] Wherein: 1-mandrel, 101-first step, 102-second step, 103-third step, 104-fourth step, 2-skirt positioning block locking nut, 3-skirt positioning block, 4-front connector locking nut, 5-pad, 6-skirt, 7-front connector, 8-insulation layer, 9-rear connector, 10-dummy end cap, 11-locking nut, 12-composite material layer. Detailed implementation method:

[0028] To better illustrate the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and typical embodiments, but this should not be construed as limiting the technical solution of the present invention.

[0029] Example 1

[0030] The single-head engine composite material casing of this embodiment has a rotating structure, including a skirt 6, a front arc-shaped contraction section, and a rear straight section, as shown below. Figure 1 As shown. Skirt 6, a rotating structure, has steps on its outer side, as... Figure 2As shown. The arc-shaped contraction section, from the inside out, includes an insulation layer 8, a front connector 7, and a composite material layer 12; a 72mm diameter pole hole is opened at its axial center. The straight section has an inner diameter of 160mm and consists of an inner insulation layer 8, an outer composite material layer 12, and a rear connector 9; the front section of the rear connector 9 is located between the insulation layer 8 and the composite material layer 12, and the outer surface of the rear section is flush with the outer surface of the composite material layer 12, with internal threads on the inner wall. The skirt 6 is located outside the arc-shaped contraction section, and its rear end is located inside the composite material layer 12. The burst pressure requirement for the composite material casing of this single-head engine is 35MPa.

[0031] The composite material casing for the single-head engine in this embodiment was prepared using the dummy head method. The specific steps are as follows:

[0032] The winding angle of the arc-shaped contraction section of the shell is calculated to be 27° using formula (1).

[0033] (1)

[0034] In the formula, It is the extreme diameter of the composite material casing of a single-head engine. It is the inner diameter of the straight section of the composite material casing of a single-head engine.

[0035] The arrangement of the hanging pins on the outer surface of the front end of the rear connector 9 is designed according to the winding angle. To increase the connection strength between the rear connector 9 and the composite material layer 12, pointed hanging pins are provided on the outer surface of the front end of the rear connector 9. The hanging pins are evenly distributed on the outer surface of the front end of the connector 9, arranged circumferentially parallel to the end face of the connector 9, in a total of 6 rows, with a spacing of 10mm between adjacent rows; the angle β between the line connecting adjacent hanging pins in each row and the center of the circle they belong to is 7.5°, such as... Figure 3 As shown. The vertical arrangement and winding angle are consistent with the size and direction, forming an angle of 27° with the vertical direction, with adjacent columns spaced 10mm apart. For example... Figure 4 As shown.

[0036] The mold is constructed from a mandrel 1, a skirt positioning block locking nut 2, a skirt positioning block 3, a front connector locking nut 4, a pad 5, a dummy end cap 10, and a locking nut 11. Figure 1 As shown.

[0037] The mandrel 1 is a rotating structure, consisting of a large cylinder with a diameter of 160mm in the middle and smaller cylinders with steps at both ends. The front cylinder has two steps that increase in size from front to back: the outer diameter of the frontmost cylinder is 60mm, the outer diameter of the first step 101 is 65mm, and the outer diameter of the second step 102 is 72mm. External threads are provided on the outer surfaces of the front ends of both the first step 101 and the second step 102. The rear cylinder has two steps that decrease in size from front to back: the outer diameter of the third step 103 is 80mm, and the outer diameter of the fourth step 104 is 75mm. External threads are provided on the fourth step 104 50mm from the rear end face of the third step 103. Figure 5 As shown.

[0038] Skirt positioning block 3 is a rotating structure with a cross-section of a 10mm thick thin plate bent into a shape. Through bending deformation, the thin plate changes from a vertical structure at the front end to a horizontal structure at the rear end. A step is set on the inner surface of the rear end to match the step on the outer side of skirt 6; an opening at the axis has a diameter of 65mm. (Example:) Figure 6 As shown.

[0039] The dummy head 10 has a rotating body structure. The front section has a stepped structure with external threads on the outer surface of the front end of the step, which match the internal threads on the inner wall of the rear connecting part 9. The rear section has an arc-shaped shrinkage structure with an 85mm extreme hole at the shaft center.

[0040] Subsequently, the composite material casing of the single-head engine in this embodiment is prepared using a mold. The steps are as follows:

[0041] 1) Fix the mandrel 1 and lay the insulation layer 8 on the outside of its large cylinder. At the front end of the mandrel 1, put the front connector 7 on the second step 102 of the small cylinder and fit it against the insulation layer 8 in front of the large cylinder; put on the pad 5, and then use the locking nut 4 of the front connector and the external thread of the second step 102 of the small cylinder to fix the front connector 7. At the rear end of the mandrel 1, place the front part of the rear connector 9 on the outside of the insulation layer 8, and then put the dummy end cap 10 on the fourth step 104 of the mandrel 1 and thread it with the rear part of the rear connector 9 until the rear end face of the rear connector 9 contacts the step end face of the dummy end cap 10. At this time, the outer surface of the rear connector 9 is flush with the outer surface of the dummy end cap 10; the locking nut 11 is threaded with the external thread of the fourth step, and the position of the dummy end cap 10 is fixed by means of the locking nut 11 and the third step 103.

[0042] 2) On the outer surface of the front connector 7, the insulation layer 8, and the front section of the rear connector 9, the composite material layer 12 is wound at a 27° winding angle to connect the front connector 7 and the rear connector 9 together, ensuring the sealing performance and ablation resistance of the shell. The dummy end cap 10 is wrapped during the winding of the composite material layer 12. The skirt 6 and the skirt positioning block 3 are positioned and connected using their respective steps, and fixed with threads or pins. After the composite material layer 12 is wound to a thickness of 3mm, the skirt positioning block 3 is fitted onto the first step 101 of the small cylinder at the front end of the mandrel 1. The skirt positioning block locking nut 2 is connected to the external thread at the front end of the first step 101, and the position of the skirt positioning block 3 is fixed by means of the skirt positioning block locking nut 2 and the second step 102. The composite material layer 12 continues to be wound on the outer side until the preset thickness is reached.

[0043] 3) After the winding is completed, it is cured using a hot autoclave molding process.

[0044] 4) After curing, the dummy head 10 is removed by machining, and the remaining molds are removed, thus completing the preparation of the single-head engine composite material shell.

[0045] The composite material casing of the single-head engine prepared in this embodiment failed in the hydrostatic burst test, with the burst pressure reaching 40 MPa and the fiber strength reaching more than 85%, thus meeting the strength requirements.

[0046] Example 2

[0047] The difference from Example 1 is as follows:

[0048] The rear connector 9 has a 6° angle β between the line connecting adjacent pins in each row and the center of the circle it belongs to, and a 24° angle between the vertical arrangement direction and the vertical direction; the inner wall of the rear section is provided with a stepped structure.

[0049] The dummy end cap 10 has a stepped structure on its front outer surface, which matches the stepped structure on the rear inner wall of the rear connector 9.

[0050] Example 3

[0051] The difference from Example 1 is as follows:

[0052] The rear connector 9 has a 9° angle β between the line connecting adjacent pins in each row to the center of the circle it belongs to, and a 30° angle between the vertical arrangement direction and the vertical direction.

Claims

1. A method for preparing a composite material casing for a single-head engine, the composite material casing comprising a skirt, a front arc-shaped contraction section, and a rear straight section; the arc-shaped contraction section comprising, from the inside out, an insulation layer, a front connector, and a composite material layer; the straight section comprising an inner insulation layer, an outer composite material layer, and a rear connector, the front section of the rear connector being located between the insulation layer and the composite material layer; the skirt being located outside the arc-shaped contraction section, its rear end being located inside the composite material layer, characterized in that, The preparation steps are as follows: 1) Calculate the winding angle of the arc-shaped contraction section of the single-head composite material shell; 2) The front end of the connector (9) is arranged with pins according to the design of the winding angle; the angle β between the line connecting the adjacent pins in each row and the center of the circle is 6°~9°, and the angle between the vertical arrangement direction and the vertical direction is the winding angle ±3°. 3) Prepare a mold, including a mandrel (1), a skirt fixing device, a front connector fixing device, a dummy head (10), and a dummy head fixing device; the mandrel (1) includes a large cylinder in the middle and small cylinders at the front and rear ends, used to form a composite material shell, and to fix the skirt fixing device, the front connector fixing device, and the dummy head fixing device; the dummy head (10) has a front section used to fix the rear connector (9), and a rear section with an arc-shaped shrinkage structure; the skirt fixing device, the front connector fixing device, and the dummy head fixing device are used to fix the skirt, the front connector, and the dummy head, respectively; 4) Fix the mandrel (1) and lay an insulating layer (8) on the outside of its large cylinder; at the front end of the mandrel (1), put the front connector (7) on the small cylinder and fit it with the laid insulation layer (8), and fix its position using the front connector fixing device; at the rear end of the mandrel (1), place the front section of the rear connector (9) on the outside of the insulation layer, and then put the dummy end cap (10) on the small cylinder, and fix the position of the dummy end cap (10) using the dummy end cap fixing device; 5) Wrap the composite material layer (12) on the outer surface of the front connector (7), the insulation layer (8) and the front section of the rear connector (9) with the calculated winding angle; after the composite material layer (12) is wound to the designed thickness, place the skirt (6) and fix its position using the skirt fixing device; continue to wrap the composite material layer (12) on the outside until the preset thickness is reached; 6) After winding, cure using a curing process; 7) After curing, remove the mold to complete the preparation of the composite material shell for the single-head engine.

2. The method for preparing a single-head engine composite material casing according to claim 1, characterized in that, The angle β between the line connecting adjacent nails in each row and the center of the circle is 7.5°, and the angle between the vertical arrangement direction and the vertical direction is the winding angle.

3. The method for preparing a single-head engine composite material casing according to claim 1, characterized in that, The skirt fixing device includes a skirt positioning block locking nut (2) and a skirt positioning block (3).

4. The method for preparing a single-head engine composite material casing according to claim 1, characterized in that, The front connector fixing device includes a front connector locking nut (4).

5. The method for preparing a single-head engine composite material casing according to claim 4, characterized in that, The front connector fixing device also includes a pad (5).

6. The method for preparing a single-head engine composite material casing according to claim 1, characterized in that, The dummy head fixing device is a locking nut (11).

7. The method for preparing a single-head engine composite material casing according to claim 1, characterized in that, The front end of the mandrel (1) has two steps, which increase in size from front to back; the rear end of the mandrel has two steps, which decrease in size from front to back.

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