Forming method of fiber reinforced composite material heat insulation shell

Abstract

The invention discloses a forming method of a fiber reinforced composite heat insulation shell. According to the scheme, the method comprises the steps of preparing and forming a raw rubber strip of the heat insulation material, pretreating a core mold, winding raw rubber, tightening a heat insulation layer, repairing, winding a shell layer and co-curing the shell layer and the heat insulation layer. According to the winding forming method for the heat insulation material, the unmanned forming process can be basically achieved, harm of toxic and harmful substances to personnel health is reduced, the quality consistency of the heat insulation layer can be improved, the forming efficiency of the heat insulation layer is improved to a great extent, and the effect on a large shell is more obvious.

Description

Technical Field

[0001] The invention relates to the field of thermal insulation layers of solid rocket engines, and more specifically to a method for forming a thermal insulation shell of a fiber-reinforced composite material. Background Art

[0002] When solid rocket engines are working, the gas temperature can reach over 3000K, and it is usually necessary to lay insulation materials inside the shell for thermal protection. Commonly used insulation materials are polymer-based composite materials made of EPDM rubber or nitrile rubber as a matrix, mixed with reinforcing fibers and functional powders. With the large-scale promotion and application of fiber-reinforced composite shells, the insulation layer molding process has changed from the traditional method of laying the insulation layer inside the steel shell and then pressurizing and vulcanizing it to laying the insulation layer on the sand core mold, then winding the reinforcing fibers and resin materials on the insulation layer, and finally co-curing it.

[0003] Specifically, the operator needs to design different insulation layer shapes according to the design requirements, and then cut the corresponding insulation layer according to the thickness requirements of different parts, and then lay it on the core mold (such as Figure 1 After the first layer is laid, it needs to be tightened and then repaired manually. After applying adhesive, it is laid for the second time and then tightened and repaired manually, and so on until the design requirements are met. This manual laying method is not only complicated to operate, has a long operation cycle, and the molding quality is very dependent on the technical maturity of the operator, but also the consistency of the airtightness quality of the shell is difficult to control. Summary of the invention

[0004] In view of the defects or shortcomings of the prior art, the present invention provides a method for forming a fiber reinforced composite material insulation shell.

[0005] To this end, the fiber reinforced composite material insulation shell molding method provided by the present invention comprises the following steps:

[0006] Step 1, using a raw rubber cutting machine to extrude the mixed EPDM rubber insulation material raw rubber into a strip shape, then collecting the strip-shaped insulation material raw rubber into a roll to obtain the insulation material raw rubber roll material, and in the process of collecting and rolling, brushing a release agent on the surface of the strip-shaped insulation material raw rubber to prevent the raw rubber from sticking; the strip-shaped insulation material raw rubber has a thickness of 0.5 to 3 mm and a width of 2 to 20 mm;

[0007] Laying a protective layer on the surface of the core mold;

[0008] Step 2: Using a raw rubber winding machine, the raw rubber coil of the heat-insulating material is wound onto the surface of the core mold with the protective layer on the surface until the designed thickness is reached, thereby forming a heat-insulating layer on the surface of the core mold; and before the raw rubber coil of the heat-insulating material is connected to the raw rubber winding machine, an organic solvent is brushed on the surface of the raw rubber and wiped to clean the release agent;

[0009] Among them, the winding tension of the raw rubber winding machine not only makes the strip-shaped thermal insulation material raw rubber tight, but also ensures that the maximum deformation rate of the strip-shaped thermal insulation material raw rubber does not exceed 10%; the winding trajectory is: the strip-shaped thermal insulation material raw rubber is wound around the core mold axial spiral line to the surface of the core mold, and during each winding process: the strip-shaped thermal insulation material raw rubber is wound from one axial end of the core shaft to the other axial end, and the inclination angle of the strip-shaped thermal insulation material raw rubber relative to the core shaft axis is an acute angle;

[0010] Step 3: Wrap and tighten the thermal insulation layer with a fastening material, remove the fastening material after standing, and repair the thermal insulation layer;

[0011] Step 4: Brush an adhesive for bonding with the carbon fiber reinforced composite material on the surface of the insulation layer, and after drying, wind the carbon fiber reinforced composite material to form a shell layer;

[0012] Step five, co-curing the shell layer and the heat-insulating layer in an oven, then using a demoulding machine to pull out the core mold, and cleaning the inner surface of the heat-insulating layer to obtain a formed shell.

[0013] An optional solution is that the release agent is a mixture of one or more of paraffin, talcum powder and silicone oil.

[0014] An optional solution is that the material of the protective layer is polytetrafluoroethylene cloth.

[0015] Optionally, the organic solvent is selected from alcohol, ethyl acetate or acetone.

[0016] An optional solution is that, during the winding process of step 2, on the premise that the strip-shaped insulating material raw rubber is wound along the axial spiral line around the mandrel to the surface of the mandrel as the winding trajectory, one or more of the following winding methods are selected at the same time to meet the design requirements of the winding process and the insulation layer structure:

[0017] ① During the adjacent winding process, the raw rubber of the strip-shaped thermal insulation material is distributed in parallel without gaps or in parallel with partial overlap;

[0018] ② By changing the inclination angle of the raw rubber of the strip-shaped thermal insulation material relative to the axis of the core shaft;

[0019] ③ According to the local structural requirements of the insulation layer, wrap the strip-shaped insulation material rubber around the core shaft at the local position.

[0020] An optional solution is that during the winding process of step 2, reinforcing material is laid between the insulating material raw rubber winding layers according to the design requirements of the insulating layer.

[0021] An optional solution is to brush adhesive for bonding raw rubber to raw rubber on the surface of the strip-shaped insulation material raw rubber output by the raw rubber winding machine and before it is wound onto the surface of the core mold.

[0022] Optionally, the fastening material is a polypropylene tape.

[0023] An optional solution is that the co-curing time and temperature are determined by the shell material and the insulation material, whichever has a higher curing temperature and a longer curing time.

[0024] The insulation material winding molding method of the present invention can basically realize unmanned molding process, reduce the harm of toxic and hazardous substances to personnel health. In addition, the present invention mainly ensures the molding of the insulation layer by setting equipment parameters, which can improve the quality consistency of the insulation layer. At the same time, the present invention can greatly improve the molding efficiency of the insulation layer, especially for large shells. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an example diagram of the core mold structure.

[0026] Figure 2 It is a schematic diagram of the winding trajectory of the insulating material strip of the present invention, wherein the Z axis is the axial direction of the core shaft, and the white spiral line represents the winding trajectory of the strip of raw rubber. DETAILED DESCRIPTION

[0027] Unless otherwise specified, the scientific and technical terms used herein are understood according to the knowledge of ordinary technicians in the relevant fields.

[0028] The specific components and formulations of the EPDM rubber insulation material, carbon fiber reinforced composite material, and reinforcement material described in the present invention are determined according to the design requirements of the formed insulation shell. For the functional materials or reagents such as the release agent, protective layer, release agent for cleaning organic solvents, and adhesives used in various links used in the process of the present invention, those skilled in the art can optimize and select them according to their relevant functions without affecting the realization of the purpose of the present invention, and are not limited to the selective examples of each functional material or reagent given in the present invention.

[0029] In the process of the present invention, the main winding track of the strip rubber of the heat insulation layer is in the form of a spiral line around the axial direction of the mandrel (i.e., the long axis direction of the mandrel) compared with the prior art. Based on the winding track in this way, the special-shaped structures such as edges, protrusions, steps, etc. at both ends of the mandrel are well covered by means of selective repair, partial change of the winding track, or change of the original winding direction relative to the axial direction of the mandrel, thereby improving the quality and processing efficiency of the heat insulation layer. In a specific solution, the winding method of the shell layer material can adopt the existing shell layer carbon fiber winding process.

[0030] It should be noted that for different insulation materials, according to the different mechanical properties and specifications of the materials, as well as the different sizes and aspect ratios of the core molds, the winding process of the scheme of the present invention needs to appropriately adjust the tension, the winding cross angle of the fiber material on the core mold, and the core mold rotation speed, etc., to ensure that the fibers of the insulation material are not broken or relaxed during the winding process, and the fibers can fit better with the core mold to avoid fiber overhead and fiber slippage.

[0031] The following will be combined with the embodiments of the present invention and the accompanying drawings to clearly and completely describe the technical solutions 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.

[0032] In the following examples, the EPDM rubber is 4045# rubber from Jilin Petrochemical, the aramid fiber is about 6 mm long, the carbon fiber is about 3 mm long, and fillers such as stearic acid and zinc oxide are provided by Sinopharm; the adhesives ASL-1 and ASL-3 are provided by Hubei Aerospace Chemical Technology Research Institute.

[0033] Example:

[0034] This embodiment is a specific fiber reinforced composite material shell winding molding method, comprising the following steps:

[0035] Step 1: Mix EPDM rubber (100 parts by mass) on an open mill, add aramid fiber (20 parts by mass), white carbon black (20 parts by mass), stearic acid (10 parts by mass), zinc oxide (10 parts by mass), carbon fiber (5 parts by mass), paraffin oil (10 parts by mass) and sublimated sulfur (2 parts by mass) fillers in sequence, and mix until uniform; use a raw rubber cutter (D-CDJ-50-02-00 of Maike High Materials) to calender into a 5 mm wide and 2 mm thick strip-shaped EPDM insulation material raw rubber, and brush the release agent talcum powder at the outlet of the raw rubber cutter and collect it into a roll;

[0036] according to Figure 1 Cut the polytetrafluoroethylene cloth into the shape and size of the cylindrical core mold with a diameter of 50mm as shown, and lay it on the surface of the core mold as a protective layer to remove bubbles and wrinkles for later demoulding, while protecting the surface of the insulation layer from being damaged by the core mold;

[0037] Step 2: Connect the EPDM insulation material raw rubber roll to a CNC raw rubber winding machine (SKLCR40 / 500 model of Harbin Institute of Technology), set the raw rubber winding machine tension to 1N, the rotation speed of the core mold to 5r / min, and the winding inclination direction of the raw rubber tape to an angle of 15° with the axis of the core mold;

[0038] Install a release agent cleaning device before the EPDM insulation raw rubber roll is connected to the winding machine. Use ethyl acetate to clean the surface release agent during the glue discharge process, and use gauze to wipe the release agent that may remain on the surface of the EPDM raw rubber strip and accelerate the volatilization of ethyl acetate;

[0039] An adhesive brushing device is installed at the front end of the raw rubber winding machine outlet to apply ASL-1 adhesive for bonding raw rubber to raw rubber on the raw rubber strips of EPDM insulation materials;

[0040] After fixing the starting end of the EPDM rubber strip, wrap the insulation material rubber around the core shaft in the direction of the spiral line (such as Figure 2 As shown), the raw rubber of the strip-shaped thermal insulation material is distributed in parallel without gaps, forming a thermal insulation layer with a design thickness of 4 mm;

[0041] Step 3: Use polypropylene tape to wrap and tighten the insulation layer, and let it stand for 24 hours; then remove the polypropylene tape, and according to the design requirements of the insulation layer, use a hot air blower to heat the blade to repair the raw rubber of the insulation layer, and specifically cut off the redundant structure and protrusions or fill the concave parts according to the design requirements of the insulation layer structure;

[0042] Step 4: Brush ASL-3 adhesive bonded to carbon fiber on the surface of EPDM insulation material, and after drying, the insulation layer raw rubber winding work is completed, and the carbon fiber reinforced composite material (Toray T800 carbon fiber) shell is wound to a designed thickness of 6 mm to form a shell layer;

[0043] Step five, co-curing the shell layer and the insulation layer in an oven, the first stage curing temperature is 100°C and the curing time is 0.5 hour, the second stage curing temperature is 125°C and the curing time is 1 hour, the third stage curing temperature is 150°C and the curing time is 2 hours, curing and naturally cooling, finally obtaining a formed shell.

[0044] The shell prepared in this embodiment was tested for air tightness, and the pressure holding time was 20 seconds at a pressure of 1 MPa.

[0045] The above description is only a preferred embodiment of the present invention and does not limit the technical scope of the present invention. Therefore, any slight modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for forming a fiber-reinforced composite material insulation shell, characterized in that: The method comprises the following steps: Step 1, using a raw rubber cutting machine to extrude the mixed EPDM rubber insulation material raw rubber into a strip shape, then collecting the strip-shaped insulation material raw rubber into a roll to obtain the insulation material raw rubber roll material, and in the process of collecting and rolling, brushing a release agent on the surface of the strip-shaped insulation material raw rubber to prevent the raw rubber from sticking; the strip-shaped insulation material raw rubber has a thickness of 0.5 to 3 mm and a width of 2 to 20 mm; Laying a protective layer on the surface of the core mold; Step 2: Using a raw rubber winding machine, the raw rubber coil of the heat-insulating material is wound onto the surface of the core mold with the protective layer on the surface until the designed thickness is reached, thereby forming a heat-insulating layer on the surface of the core mold; and before the raw rubber coil of the heat-insulating material is connected to the raw rubber winding machine, an organic solvent is brushed on the surface of the raw rubber and wiped to clean the release agent; Among them, the winding tension of the raw rubber winding machine not only makes the strip-shaped thermal insulation material raw rubber tight, but also ensures that the maximum deformation rate of the strip-shaped thermal insulation material raw rubber does not exceed 10%; the winding trajectory is: the strip-shaped thermal insulation material raw rubber is wound around the core mold axial spiral line to the surface of the core mold, and during each winding process: the strip-shaped thermal insulation material raw rubber is wound from one axial end of the core shaft to the other axial end, and the inclination angle of the strip-shaped thermal insulation material raw rubber relative to the core shaft axis is an acute angle; Step 3: Wrap and tighten the thermal insulation layer with a fastening material, remove the fastening material after standing, and repair the thermal insulation layer; Step 4: Brush an adhesive for bonding with the carbon fiber reinforced composite material on the surface of the insulation layer, and after drying, wind the carbon fiber reinforced composite material to form a shell layer; Step five, co-curing the shell layer and the heat-insulating layer in an oven, then using a demoulding machine to pull out the core mold, and cleaning the inner surface of the heat-insulating layer to obtain a formed shell.

2. The fiber reinforced composite material insulation shell molding method according to claim 1, characterized in that: The release agent is one or a mixture of two or more of paraffin, talcum powder and silicone oil.

3. The fiber reinforced composite material insulation shell molding method according to claim 1, characterized in that: The protective layer material is polytetrafluoroethylene cloth.

4. The method for forming a fiber-reinforced composite material insulation shell according to claim 1, characterized in that: The organic solvent is selected from alcohol, ethyl acetate or acetone.

5. The fiber reinforced composite material insulation shell molding method according to claim 1, characterized in that: In the winding process of step 2, under the premise that the strip-shaped thermal insulation material raw rubber is wound along the axial spiral line around the core mold to the surface of the core mold as the winding trajectory, one or more of the following winding methods are selected to meet the design requirements of the winding process and the thermal insulation layer structure: ① During the adjacent winding process, the raw rubber of the strip-shaped thermal insulation material is distributed in parallel without gaps or in parallel with partial overlap; ② By changing the inclination angle of the raw rubber of the strip-shaped thermal insulation material relative to the axis of the core shaft; ③ According to the local structural requirements of the insulation layer, wrap the strip-shaped insulation material rubber around the core shaft at the local position.

6. The fiber reinforced composite material insulation shell molding method according to claim 1, characterized in that: In step 2, during the winding process, reinforcing materials are laid between the insulating material raw rubber winding layers according to the design requirements of the insulating layer.

7. The fiber reinforced composite material insulation shell molding method according to claim 1, characterized in that: The surface of the raw rubber of the strip-shaped thermal insulation material output by the raw rubber winding machine and before being wound onto the surface of the core mold is brushed with adhesive for bonding the raw rubber to the raw rubber.

8. The method for forming a fiber-reinforced composite material thermal insulation shell according to claim 1, characterized in that: The fastening material is selected as a polypropylene tape.

9. The fiber reinforced composite material insulation shell molding method according to claim 1, characterized in that: The co-curing time and temperature are determined by the shell material or the insulation material, whichever has a higher curing temperature and a longer curing time.

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