Forming method for composite shell of pin-jointed large-opening solid rocket engine

Abstract

The invention discloses a forming method of a pin joint large-opening solid rocket engine composite material shell. The forming method comprises the following steps: preparing a front joint and a rear joint with sealing inserts; preparing a barrel section winding tool; assembling a winding core mold and carrying out surface treatment; preparing a shell fiber winding layer; curing the shell; and shell machining is conducted, and finally the pin-joint large-opening solid rocket engine composite shell is obtained. The forming method provided by the invention has good manufacturability, the reliability of connection between the large-opening composite shell and other cabin sections or end sockets is enhanced by adopting a double-row radial pin connection method, and meanwhile, the sealing performance of the shell is further ensured by arranging a sealing insert; and in the winding process, the complex operation of annularly winding the surface of the winding core mold and paving the prepreg for leveling is not needed, and the technological process is simple and efficient.

Description

Technical Field

[0001] The invention relates to the field of manufacturing composite material casings of solid rocket engines, and in particular to a method for forming composite material casings of solid rocket engines with pin connections having large openings. Background Art

[0002] The use of composite casings can improve the engine mass ratio. Existing composite casings are widely used in large-diameter engines, but their application in small and medium-sized diameter engines with large aspect ratios is subject to certain restrictions. The demand for large or even full casing openings in such engines is one of the reasons for the limited application of composite materials.

[0003] The composite shell of a solid rocket engine is usually formed by longitudinal and circumferential fiber winding, while there is only a longitudinal fiber winding layer in the head. The increase in the opening will reduce the strength of the head, and the head must be reinforced to avoid low-stress damage. At the same time, for large-opening shells with relatively large polar holes at the front and rear ends, the change in the winding angle will exceed a certain value, which will cause problems such as yarn slippage and linear instability during the winding process. Currently, the main wet winding process is adopted, using a small angle (9°~12°) longitudinal winding method, such as patent CN11070734A. For the winding form without a head, a metal hanging wire ring is generally used, such as patent CN110978558A. However, these winding molding methods often require the use of fiber prepreg cloth or circumferential winding to level the winding core mold to make its surface smoother to facilitate the preparation of the winding layer, and the operation process is relatively complicated. In addition, for large-opening composite shells with head structures, the head and shell are often bonded together, such as patent CN110744832A, which effectively reduces the structural mass and increases the charge space. However, defects are prone to occur in the bonding area, resulting in reduced structural strength and the inability to exert the high load-bearing capacity of the composite material. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of the present invention is to provide a pin-connected large-opening solid rocket engine composite material casing molding method, which does not require ramp segment winding or prepreg laying and leveling operations, and enhances the reliability of the connection between the large-opening composite material casing and other compartments or heads by adopting a double-row radial pin connection method, and further ensures the sealing performance of the casing by arranging a sealing insert.

[0005] The specific technical solutions of the present invention are as follows:

[0006] A method for forming a composite material casing of a pin-connected large-opening solid rocket engine, the method comprising the following steps:

[0007] S1. Preparation of front and rear joints with sealing inserts

[0008] The "L"-shaped metal sealing rings are embedded in the front and rear joints by laying carbon fiber prepreg cloth, and finally molded to obtain the front and rear joints with sealing inserts;

[0009] S2. Preparation of barrel winding tooling

[0010] The green sheet of the heat insulation layer is rolled to a suitable thickness, cut and coated on the surface of the barrel section core mold; the inner surface of the cone section of the front and rear joints prepared in step S1 and the outer surface of the cone section of the heat insulation layer are roughened and then bonded to form a barrel section winding tooling;

[0011] S3. Winding core mold assembly and surface treatment

[0012] Assemble the barrel segment winding tooling obtained in step S2 with the front and rear head tooling to form a winding mandrel, and evenly apply a layer of adhesive on the entire winding area of ​​the surface of the winding mandrel;

[0013] S4. Preparation of Shell Fiber Winding Layer

[0014] Winding the designed layer on the winding mandrel after the surface treatment in step S3 to obtain a fiber winding layer;

[0015] S5. Shell curing

[0016] The shell wound in step S4 is placed in a curing furnace for curing, and after curing, the shell is demoulded to form a composite material shell with a head;

[0017] S6, Shell Machining

[0018] The head of the composite material shell with a head obtained in step S5 is cut, and the front and rear head tooling is removed, and radial pin holes are further drilled in the front and rear joints, and then the sealing inserts are processed in place according to the sealing performance requirements, and finally a pin-connected large-opening solid rocket engine composite material shell is obtained.

[0019] The winding core mold obtained in step S3 does not need to be leveled during the winding process.

[0020] Preferably, the inner profile of the conical section of the front and rear joints with sealing inserts prepared in step S1 is a conical surface with a small taper, and the taper range is 1° to 3°, so as to match the barrel section winding tooling formed in step S2.

[0021] Preferably, the sealing inserts in the front joint with sealing inserts and the rear joint with sealing inserts are made of metal material, the sealing inserts are provided with steps overlapping the thermal insulation layer, the axial width of the sealing inserts is 15 to 35 mm, and the width of the steps is 5 to 10 mm;

[0022] The sealing insert is used for a sealing structure, and its inner surface is machined after the composite material shell is integrally formed to meet the sealing performance requirements.

[0023] Preferably, the insulation layer material is EPDM rubber and is bonded to the sealing insert.

[0024] Furthermore, the composite shell is provided with radial pin holes, which are double-row pins for connecting with other compartments or heads, and the number of radial pin holes is selected according to specific load conditions;

[0025] Preferably, the spacing between the radial pin hole axes is greater than twice the hole diameter;

[0026] Preferably, the composite shell uses double-row pins of Φ12 mm, the spacing between the radial pin hole axes is 30 mm, and the spacing between the joint end faces of the front joint with sealing insert or the rear joint with sealing insert is 25 mm.

[0027] Furthermore, the winding angle of the composite material shell in step S3 can be designed by adjusting the front and rear end cap holes;

[0028] Preferably, the front and rear head sealing tools adopt a front and rear equipolar hole solution.

[0029] Furthermore, the front and rear pole hole ratio can be adjusted according to the axial stiffness requirements of the composite shell.

[0030] Preferably, when the composite material shell has large openings at both ends, equal polar hole winding is adopted, and the winding angle is 12°.

[0031] Furthermore, when a single-sided sealing head is retained, the retained sealing head is reinforced during the winding process, so as to form a composite material shell with a single-sided large opening.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The molding method disclosed in the present invention not only has good processability, but also adopts a double-row radial pin connection method that effectively improves the connection reliability between the composite material shell and other compartments or heads. The designed sealing insert ensures that the composite material shell has good sealing performance. At the same time, during the winding process, there is no need for complex operations such as annular winding and laying prepreg for leveling, and the process is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions disclosed in the present invention, the following briefly introduces the drawings required to be used in some embodiments disclosed in the present invention. Obviously, the drawings described below are only drawings of some embodiments disclosed in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings. In addition, the drawings described below can be regarded as schematic diagrams, and are not limitations on the actual size of the products involved in the embodiments disclosed in the present invention, the actual process of the method, etc.

[0035] Figure 1 A schematic diagram of a pin-connected large-opening solid rocket engine composite material casing structure provided in an embodiment of the present invention.

[0036] Figure 2 A schematic diagram of the assembled winding core mold provided in an embodiment of the present invention.

[0037] Figure 3 A joint with a sealing insert provided in an embodiment of the present invention.

[0038] The accompanying drawings are marked as follows:

[0039] 1. Front joint with sealing insert; 2. Rear joint with sealing insert; 3. Fiber winding layer; 4. Insulation layer; 5. Front head tooling; 6. Rear head tooling; 7. Front head positioning nut; 8. Rear head positioning nut; 9. Winding main shaft; 10. Sealing insert. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] The present invention provides a method for forming a composite material casing of a pin-connected large-opening solid rocket engine, the method comprising the following steps:

[0042] S1. Preparation of front and rear joints with sealing inserts

[0043] The "L"-shaped metal sealing rings are embedded in the front and rear joints by laying carbon fiber prepreg cloth, and finally molded to obtain the front and rear joints with sealing inserts;

[0044] The inner profile of the conical section of the front and rear joints with the sealing insert is a conical surface with a small taper, and the taper range is 1° to 3°, so as to match the barrel winding tooling described in step S2;

[0045] S2. Preparation of barrel winding tooling

[0046] The green sheet of the heat insulation layer is rolled to a suitable thickness, cut and coated on the surface of the barrel section core mold; the inner surface of the cone section of the front and rear joints prepared in step S1 and the outer surface of the cone section of the heat insulation layer are roughened and then bonded to form a barrel section winding tooling;

[0047] The sealing inserts in the front joint with sealing inserts and the rear joint with sealing inserts are made of metal material, the sealing inserts are provided with steps overlapping the thermal insulation layer, the axial width of the sealing inserts is 15 to 35 mm, and the width of the steps is 5 to 10 mm;

[0048] The insulation layer material is EPDM rubber and is bonded to the sealing insert;

[0049] S3. Winding core mold assembly and surface treatment

[0050] Assemble the barrel segment winding tooling obtained in step S2 with the front and rear head tooling to form a winding mandrel, and evenly apply a layer of adhesive on the entire winding area of ​​the surface of the winding mandrel;

[0051] The winding core mold does not need to be leveled during the winding process;

[0052] The front and rear end capping fixtures adopt a front and rear equal polarity hole scheme, and the front and rear equal polarity hole ratio of the front and rear end capping fixtures is designed according to the axial stiffness requirements of the composite material shell;

[0053] S4. Preparation of Shell Fiber Winding Layer

[0054] Winding the designed layer on the winding mandrel after the surface treatment in step S3 to obtain a fiber winding layer;

[0055] The winding angle of the fiber winding layer matches the isopole holes of the front and rear head end tooling;

[0056] Preferably, when the composite material shell has large openings at both ends, equal polar hole winding is adopted, and the winding angle is 12°;

[0057] S5. Shell curing

[0058] The shell wound in step S4 is placed in a curing furnace for curing, and after curing, the shell is demoulded to form a composite material shell with a head;

[0059] S6, Shell Machining

[0060] The head of the composite material shell with a head obtained in step S5 is cut, and the front and rear head tooling is removed, and radial pin holes are further drilled in the front and rear joints, and then the sealing inserts are processed in place according to the sealing performance requirements, and finally a pin-connected large-opening solid rocket engine composite material shell is obtained.

[0061] The sealing insert is used for a sealing structure, and its inner surface is machined after the composite material shell is integrally formed to meet the sealing performance requirements.

[0062] The composite shell is provided with radial pin holes, which are double-row pins for connecting with other compartments or heads. The number of radial pin holes is selected according to the specific load conditions; the spacing between the axes of the radial pin holes is greater than 2 times the diameter of the hole. Preferably, the composite shell uses double-row pins of Φ12mm, the spacing between the axes of the radial pin holes is 30mm, and the spacing between the joint end faces of the front joint with sealing insert or the rear joint with sealing insert is 25mm.

[0063] When a single-side sealing head is retained, the retained sealing head is reinforced during the winding process, so as to form a composite material shell with a single-side large opening.

[0064] Example 1

[0065] The present embodiment provides a method for forming a composite material casing of a pin-connected large-opening solid rocket engine, the process of the molding method is: preparing front and rear joints with sealing inserts, preparing barrel winding tooling, assembling the winding core mold and performing surface treatment on the core mold, preparing the casing fiber winding layer, curing the casing fiber winding layer in a furnace, and machining the casing.

[0066] The pressure-bearing structure of the large-opening composite material shell is designed according to the design pressure of the solid rocket engine combustion chamber shell. The specific process is as follows:

[0067] First, the winding mandrel of the shell is equipped with a false head, and the radius of the front and rear polar holes is adjusted by the mandrel design to adjust the winding angle. For composite shells with a large aspect ratio, axial stiffness is also an important assessment indicator. Therefore, a small-angle spiral winding is used to enhance the axial stiffness of the shell, and the front and rear equal polar holes are used to achieve geodesic winding to stabilize the winding line shape. Therefore, the diameters of the front and rear polar holes are both 20mm, the outer diameter of the barrel section is 230mm, and the spiral winding angle is calculated as follows:

[0068]

[0069] The calculation shows that the spiral winding angle is 5°, and the spiral fiber winding thickness hα and the circumferential fiber winding thickness hθ are calculated using equations (2) and (3). The calculation formulas are as follows, where the safety factor K is safe Take 1.5:

[0070]

[0071] After substituting the fiber strength and other data into the calculation, it was found that there were 10 spiral layers, 7 circumferential layers, and the shell thickness was 2.6 mm.

[0072] After the shell is formed, the barrel section is under pressure. The bursting pressure of the barrel section is calculated using formula (4), and the bursting pressure of the spiral layer is 33.75 MPa, and the bursting pressure of the annular layer is 37.14 MPa. Therefore, the comprehensive bursting pressure of the shell under this layer design scheme reaches 33.75 MPa.

[0073]

[0074] The pin-connected large-opening solid rocket engine composite shell structure finally obtained by the molding method provided in this embodiment is as follows Figure 1 As shown, the composite material shell includes: a front joint 1 with a sealing insert, a rear joint 2 with a sealing insert, a fiber winding layer 3, and a heat insulation layer 4.

[0075] In the molding method, the inner surface of the conical section of the front joint 1 with sealing insert and the rear joint 2 with sealing insert and the outer surface of the conical section of the insulation layer 4 are roughened and then bonded with 730 adhesive to form a barrel winding tool; the front joint 1 with sealing insert and the rear joint 2 with sealing insert are cylinders with tapered inner surfaces, and the taper range is 1° to 3°, so as to match and form the above-mentioned barrel winding tool; the barrel winding tool is combined with the front head tool 5, the rear head tool 6, the front head positioning nut 7, the rear head positioning nut 8 and the winding main shaft 9 to realize the assembly of the winding core mold, such as Figure 2 As shown, a layer of H2 adhesive is evenly applied on the entire winding area; the winding core mold does not need to be leveled during the winding process.

[0076] In addition, a sealing insert 10 is pre-placed in the joint in the form of Figure 3 As shown, carbon fiber prepreg is laid according to the design parameters of the front and rear joint structures. Generally, symmetrical plies are selected for the layup, and molded to obtain the front joint 1 with sealing insert and the rear joint 2 with sealing insert; the sealing insert 10 is made of metal material and is provided with a step overlapping the thermal insulation layer 4; the sealing insert 10 is used for the sealing structure, and its inner surface is machined after the overall molding of the composite shell to meet the sealing performance requirements.

[0077] Although the present invention has been disclosed as a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solution of the present invention by using the above disclosed content without departing from the spirit and scope of the present invention. Therefore, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall belong to the protection scope of the technical solution of the present invention. The protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for forming a composite material casing of a pin-jointed large-opening solid rocket engine, characterized in that: The molding method comprises the following steps: S1. Preparation of front and rear joints with sealing inserts The "L"-shaped metal sealing rings are embedded in the front and rear joints by laying carbon fiber prepreg cloth, and finally molded to obtain the front and rear joints with sealing inserts; S2. Preparation of barrel winding tooling The green sheet of the heat insulation layer is rolled to a suitable thickness, cut and coated on the surface of the barrel section core mold; the inner surface of the cone section of the front and rear joints prepared in step S1 and the outer surface of the cone section of the heat insulation layer are roughened and then bonded to form a barrel section winding tooling; S3. Winding core mold assembly and surface treatment Assemble the barrel segment winding tooling obtained in step S2 with the front and rear head tooling to form a winding mandrel, and evenly apply a layer of adhesive on the entire winding area of ​​the surface of the winding mandrel; S4. Preparation of Shell Fiber Winding Layer Winding the designed layer on the winding mandrel after the surface treatment in step S3 to obtain a fiber winding layer; S5. Shell curing The shell wound in step S4 is placed in a curing furnace for curing, and after curing, the shell is demoulded to form a composite material shell with a head; S6, Shell Machining The head of the composite material shell with a head obtained in step S5 is cut, and the front and rear head tooling is removed, and radial pin holes are further drilled in the front and rear joints, and then the sealing inserts are processed in place according to the sealing performance requirements, and finally a pin-connected large-opening solid rocket engine composite material shell is obtained.

2. The composite material shell forming method according to claim 1, characterized in that: The inner profile of the conical section of the front and rear joints with sealing inserts prepared in step S1 is a conical surface with a small taper, and the taper range is 1° to 3°, so as to match the barrel section winding tooling formed in step S2.

3. The composite material shell forming method according to claim 1, characterized in that: The winding core mold obtained in step S3 does not need to be leveled during the winding process.

4. The composite material shell forming method according to claim 1, characterized in that: The sealing inserts in the front joint with sealing inserts and the rear joint with sealing inserts are made of metal material, the sealing inserts are provided with steps overlapping the thermal insulation layer, the axial width of the sealing inserts is 15 to 35 mm, and the width of the steps is 5 to 10 mm.

5. The composite material shell forming method according to claim 1 or 4, characterized in that: The sealing insert is used for a sealing structure, and its inner surface is machined after the composite material shell is integrally formed to meet the sealing performance requirements.

6. The composite material shell forming method according to claim 1, characterized in that: The composite shell is provided with radial pin holes, which are double-row pins and are used to connect with other compartments or heads. The number of radial pin holes is selected according to specific load conditions.

7. The composite material shell forming method according to claim 6, characterized in that: The distance between the axes of the radial pin holes is greater than twice the hole diameter.

8. The composite material shell forming method according to claim 1, characterized in that: In step S3, the front and rear head end tooling adopts a front and rear equal polar hole scheme, and the front and rear polar hole ratio is adjusted according to the axial stiffness requirements of the composite material shell.

9. The composite material shell forming method according to claim 1 or 4, characterized in that: The winding angle of the composite material shell in step S3 is designed by adjusting the front and rear end cap holes.

10. The composite material shell forming method according to claim 1, characterized in that: When a single-side sealing head is retained, the retained sealing head is reinforced during the winding process, so as to form a composite material shell with a single-side large opening.

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