Spraying forming method for large-diameter fiber winding shell

Abstract

The invention discloses a spraying forming method for a large-diameter fiber winding shell. The spraying forming method comprises the following steps that (1) a winding core mold is formed and machined; 2) injection molding of heat insulation layers of the front and rear sealing heads; (3) the front and rear end socket heat insulation layers are installed on the winding core mold; 4) winding the winding layer; (5) rotating, curing and demolding the winding layer; (6) the inner surface of the barrel section winding layer is coated with a surface treating agent; (7) spraying and forming the heat insulation layer of the cylinder section; 8) curing the heat insulation layer of the cylinder section; and 9) finishing the heat insulation layer to obtain the shell. The front end socket and the rear end socket are formed through injection, and the forming process is simple; the front end socket and the rear end socket are installed firstly, the winding layer is formed, and finally the cylinder section part is sprayed and formed, so that procedures such as manual surface mounting are replaced, and the production efficiency and the quality consistency are improved; the surface quality of the heat insulation layer formed by adopting the spray forming heat insulation layer is higher, and the heat insulation appearance problem caused by the core mold quality problem is avoided; the novel spraying heat insulation layer is adopted, the ablation rate of the heat insulation layer is lower, and the heat insulation performance is higher.

Description

Technical Field

[0001] The invention relates to the technical field of solid rocket engine casing molding, and in particular to a large-diameter fiber-wound casing spray molding method. Background Art

[0002] The main molding method of solid rocket fiber-wound engine casing is: the front and rear head insulation layers are molded by compression molding, and then the front and rear head insulation layers are mounted on the core mold, and then the barrel insulation layer is molded by manual patching, and then subsequent winding, curing, and demolding are performed to obtain the final fiber-wound casing. For example, the Chinese invention patent with application number CN201210089968.7 discloses a manual patching method for the insulation layer of a fiber-wound engine casing, which controls the manual patching preparation environment, selects a suitable adhesive, adopts a multi-layer patching method to reduce the thickness of a single-layer manual patch film, reduces the patch size, and then pre-pressurizes the fiber yarn, and then repairs the insulation layer, thereby increasing the internal quality and external structural dimensions of the insulation layer after curing, thereby making a manual patch. The present invention solves the problems of EPDM materials due to high film hardness, poor self-adhesion and mutual adhesion, and high patching difficulty. The thickness of the insulation layer meets the design requirements, the EPDM dissection layer is dense, and it has successfully passed multiple engine ground test assessments. However, for large shells, this method requires a large hydraulic press before and after molding the head, and the barrel segment patch adopts a manual molding solution, which has high requirements for equipment, high reliance on manual labor during the molding process, and low molding efficiency. Moreover, after molding, due to the large size of the shell, there are usually multiple cracks on the surface of the core mold, which eventually causes insulation defects and affects the quality of the shell.

[0003] For the molding of insulation layers of large fiber-wound shells, it is urgent to develop new molding methods to improve molding efficiency and shell quality. Summary of the invention

[0004] In order to overcome the deficiencies of the above-mentioned technologies, the purpose of the present invention is to provide a method for spraying and molding a large-diameter fiber-wound shell, so as to solve the problems of low molding efficiency, high dependence on manual work and unstable shell quality during the molding of the insulation layer of a large-diameter fiber-wound shell.

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

[0006] A method for spraying and molding a large-diameter fiber-wound shell comprises the following steps: 1) molding and machining a winding core mold; 2) injection molding of front and rear head insulation layers; 3) installing the front and rear head insulation layers on a winding core mold; 4) winding the winding layers; 5) rotationally curing and demoulding the winding layers; 6) applying a surface treatment agent on the inner surface of the barrel winding layer; 7) spraying and molding the barrel insulation layer; 8) curing the barrel insulation layer; 9) trimming the insulation layer to obtain a shell.

[0007] Furthermore, the diameter of the shell barrel section is ≥1m, and the diameters of the front and rear openings of the shell are both ≥300mm.

[0008] As a preferred solution, in step 1), the winding core mold is prepared by using any one of a gypsum surface core mold, a metal core mold, a water-soluble core mold and a metal skeleton; the machining includes coating a putty layer on the formed winding core mold, and then performing CNC machining according to the inner profile of the front and rear head insulation layer + the inner profile of the shell barrel winding layer. The thickness of the putty layer can be selected to be 0.5 to 2 mm. Coating the putty layer can effectively improve the hardness and smoothness of the winding core mold surface, thereby improving the surface quality of the shell after molding.

[0009] As a preferred solution, the insulation layer material includes liquid silicone rubber material. Liquid silicone rubber material can be coupled with carbon fiber reinforced resin under the action of silane coupling agent to obtain a composite material with good strength, hardness, wear resistance, aging resistance and other properties.

[0010] Furthermore, the liquid silicone rubber is modified liquid silicone rubber.

[0011] Furthermore, metal joints are arranged in the front and rear head insulation layers. The metal joint in the front head is used to connect with the engine ignition device, and the metal joint in the rear head is used to connect with the nozzle.

[0012] Furthermore, the step 2) includes: injecting the liquid insulation layer material into a cavity with a metal joint pre-installed therein by injection molding, and then solidifying it to prepare the front and rear head insulation layers respectively. The injection molding method has high injection molding efficiency and can ensure stable product quality.

[0013] Furthermore, in step 3), the front and rear heads formed in step 2) are installed on the winding core mold in step 1), and the distance between the front and rear heads is controlled to control the final length of the shell.

[0014] As a preferred solution, in step 4), the raw material used for the winding layer includes carbon fiber reinforced resin, preferably carbon fiber reinforced epoxy resin. The carbon fiber is T700 grade carbon fiber or T800 grade carbon fiber. The use of high-strength carbon fiber can fully ensure the strength of the shell.

[0015] Furthermore, the step 4) includes: applying a surface treatment agent on the outer surfaces of the front and rear head insulation layers and then wrapping the shell.

[0016] Furthermore, the rotational curing in step 5) includes connecting the front and rear mandrels of the winding core mold to a power rotation device, and then realizing the rotational curing of the shell, and the curing temperature is 90°C / 1h+125°C / 4h+150°C / 10h. After the rotational curing of the shell is completed, the core mold of the shell is removed to obtain a shell without a barrel section insulation layer.

[0017] As a preferred solution, in step 5), the rotation rate of the rotational curing is 0.5 to 2 rpm. A rotation rate that is too slow will cause the resin to flow down and affect the quality of the cured product. A rotation rate that is too fast will cause the inertia of the rotation process to be large due to the large mass of the winding core mold, and there will be safety hazards such as the core mold falling. Controlling the rotational curing rate to 0.5 to 2 rpm can not only ensure that the quality of the cured product meets the performance requirements, but also meet the safety requirements during the curing process.

[0018] As a preferred embodiment, in step 4) and step 6), the surface treatment agent is a silane coupling agent. The silane coupling agent is used to couple the thermal insulation layer and the wrapping layer to improve the adhesion between the thermal insulation layer and the wrapping layer, making the bonding interface more firm, uniform and tight.

[0019] Further, step 6) includes: grinding the inner surface of the winding layer of the shell barrel section obtained in step 5) with sandpaper, then cleaning it with ethyl acetate or alcohol, and applying a special surface treatment agent after drying. The fibers must not be damaged during grinding.

[0020] Furthermore, step 7) includes spraying a heat insulation layer material onto the inner surface of the shell barrel section coated with the surface treatment agent.

[0021] As a preferred solution, in step 8), the curing temperature is 18-60°C, and the curing time is adjusted according to the thickness of the insulation layer, and the curing time is 10-14h / 1mm insulation layer thickness. The curing temperature within 60°C can meet the safety requirements.

[0022] Furthermore, step 9) includes: grinding the protrusions on the surface of the formed insulation layer and repairing the local pits, so that the thickness of the insulation layer at each location of the shell finally meets the design requirements.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention provides a method for spraying and molding a large-diameter fiber-wound shell, wherein the front and rear head insulation layers are prepared by injection molding, and the barrel section insulation layer is obtained by spraying. The method has good molding quality consistency, strong process reliability, and high molding efficiency, and is suitable for large-diameter fiber-wound shells.

[0025] In the method of the present invention, the front and rear heads are injection molded, and a set of injection systems can meet the molding of heads of various specifications. In the molding process, no large hydraulic press is required, and the injection molding efficiency is high, which can ensure stable product quality. The method of the present invention replaces manual patching and other processes by first installing the front and rear heads, molding the winding layer, and finally spraying the barrel section, thereby improving production efficiency and quality consistency. The present invention adopts spray-molded thermal insulation layer, and the surface quality of the molded thermal insulation layer is higher, avoiding the thermal insulation appearance problem caused by the quality problem of the core mold. The present invention adopts liquid silicone rubber spray thermal insulation layer, and the thermal insulation layer has a lower ablation rate and higher thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A spray-coated heat-insulating fiber-wound shell prepared by the method of the present invention;

[0027] In the figure: front head insulation layer 1; barrel section insulation layer 2; rear head insulation layer 3; winding layer 4. DETAILED DESCRIPTION

[0028] In order to better explain the present invention, the main contents of the present invention are further explained below in combination with specific embodiments and drawings, but the contents of the present invention are not limited to the following embodiments.

[0029] Example

[0030] like Figure 1 As shown, the shell consists of a front end insulation layer 1, a rear end insulation layer 3, a barrel insulation layer 2 located between the front end insulation layer 1 and the rear end insulation layer 3, and a winding layer 4. The winding layer 4 is wrapped around the outer surface of the front end insulation layer 1, the barrel insulation layer 2, and the rear end insulation layer 3. The structure of the shell is the existing technology. Among them, the diameter of the shell barrel section is , length is 5500mm, the diameter of the front opening of the shell is , the diameter of the rear opening of the shell is The thickness of the insulation layer of the cylinder section is 2mm.

[0031] The above-mentioned shell is prepared by a large-diameter fiber winding shell spray molding method of the present invention, comprising the following steps:

[0032] 1) According to the size of the fiber winding shell, a metal skeleton + gypsum core mold scheme was selected. After the gypsum core mold was formed, a 1 mm thick putty layer was scraped on its surface. Then, according to the inner surface of the front head insulation layer 1 and the rear head insulation layer 3 after the winding core mold was formed + the inner surface of the winding layer 4 barrel section, CNC machining was performed to obtain the winding core mold.

[0033] 2) The front and rear head insulation layers 1 and 3 are injection molded by using the front and rear head injection molds and the modified liquid silicone rubber insulation material, and the insulation material is injected into the cavity with the metal joint pre-installed inside, and then cured to form the front and rear head insulation layers with metal joints; wherein the injection pressure is 4MPa and the injection temperature is 40°C. The modified liquid silicone rubber is a mixture of liquid silicone rubber, carbon fiber and glass microspheres.

[0034] 3) Install the above-mentioned injection-molded front and rear head insulation layers to the end of the winding core mold formed in the above step 1), and tighten the nuts through the tooling to ensure the total length of the shell.

[0035] 4) Silane coupling agent KH560 is applied on the outer surfaces of the front head insulation layer 1 and the rear head insulation layer 3, and then T700 carbon fiber reinforced epoxy resin is used for shell winding, wherein there are 12 layers in the longitudinal direction, 16 layers in the circumferential direction, 10 strands, and the yarn width is 22 mm.

[0036] 5) After winding is completed, a curing furnace with a rotating function is used to connect the front and rear mandrels of the winding core mold to a power rotating device and perform rotation curing, wherein the curing temperature is 90°C / 1h+125°C / 4h+150°C / 10h, and the rotation rate is 1 rpm. After the winding layer 4 is cured, the furnace temperature is lowered to below 50°C, and the forming core mold inside the winding layer 4 is removed to obtain a winding shell with front and rear heads.

[0037] 6) Grind the inner surface of the shell barrel section and the connection area with the front and rear heads (note: the fibers must not be broken), then clean the inner surface with ethyl acetate and let it air-dry for 10 to 15 minutes. Then evenly spray a layer of silane coupling agent KH560 on the inner surface of the shell winding layer 4 barrel section and let it air-dry for 15 to 20 minutes.

[0038] 7) The modified liquid silicone rubber insulation material is dissolved by gasoline, and then sprayed in layers with a single spraying thickness of 0.5 mm, and finally the spraying molding of the barrel section insulation layer 2 is completed.

[0039] 8) The shell is sprayed and cured by rotation, and then left to stand at room temperature of 25° C. for 24 hours for curing.

[0040] 9) After the barrel section insulation layer 2 was cured at room temperature for 24 hours, the inner surface of the shell insulation layer was inspected, and local pits with a depth of more than 0.5 mm were repaired by scraping with modified liquid silicone rubber, and local protrusions with a height of more than 0.8 mm were polished and smoothed. After treatment, a spray-insulated fiber-wound shell that met the design specifications was finally obtained.

[0041] The repair rate of the large-diameter filament-wound housing product prepared in this embodiment is 12%, while the repair rate of the large-diameter filament-wound housing product prepared by the traditional patch technology is 53%. It can be seen that the large-diameter filament-wound housing obtained by the method of the present invention has better product surface quality.

Claims

1. A method for spraying and molding a large-diameter fiber-wound shell, characterized in that: The following steps are involved: 1) Winding core mold molding and machining; 2) Injection molding of front and rear head insulation layers; 3) Installing the front and rear head insulation layers on the winding core mold; 4) Winding of the winding layers; 5) Rotational curing and demoulding of the winding layers; 6) Applying surface treatment agent on the inner surface of the barrel winding layer; 7) Spraying molding of the barrel insulation layer; 8) The insulation layer of the barrel section is cured; 9) The insulation layer is trimmed to obtain the shell.

2. The large diameter fiber winding shell spray forming method according to claim 1 is characterized in that: The diameter of the cylindrical section of the shell is ≥1m, and the diameters of the front and rear openings of the shell are both ≥300mm.

3. The large diameter fiber winding shell spray forming method according to claim 1 is characterized in that: In step 1), the winding core mold is prepared by using any one of a gypsum surface core mold, a metal core mold, a water-soluble core mold and a metal skeleton; the machining includes coating a putty layer on the formed winding core mold, and then performing CNC machining based on the inner surface of the front and rear head insulation layer + the inner surface of the shell barrel winding layer.

4. The large diameter fiber winding shell spray forming method according to claim 1, characterized in that: The raw material of the heat insulation layer includes liquid silicone rubber material.

5. The large diameter fiber winding shell spray forming method according to claim 1, characterized in that: In step 4), the raw material of the winding layer includes carbon fiber reinforced resin.

6. The large diameter fiber winding shell spray forming method according to claim 5, characterized in that: The step 4) comprises: applying a surface treatment agent on the outer surfaces of the front and rear head insulation layers and then wrapping the shell.

7. The large diameter fiber winding shell spray forming method according to claim 1, characterized in that: In step 5), the rotation rate of the rotational solidification is 0.5 to 2 revolutions per minute.

8. The large diameter fiber winding shell spray forming method according to claim 6, characterized in that: The surface treatment agent in step 4) and step 6) is a silane coupling agent.

9. The large diameter fiber winding shell spray forming method according to claim 4, characterized in that: In step 8), the curing temperature is 18 to 60° C., and the curing time is 10 to 14 h / mm thickness of the insulation layer.

10. The large-diameter fiber-wound shell spray molding method according to any one of claims 1 to 9, characterized in that: Step 9) includes: grinding the protrusions on the surface of the formed insulation layer and repairing the local pits, so that the thickness of the insulation layer at each location of the shell finally meets the design requirements.

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