A method for forming a composite mounting base with an integrally formed internal threaded structure

Abstract

The application discloses a molding method of a composite material mounting seat with an integrally-formed inner thread structure in the technical field of composite material products, and comprises the following steps: step 1) preparing a mold, adopting a male mold structure; step 2) laying up prepreg, laying up glass fiber prepreg on the surface of the mold, including the surface of a bottom plate and the surface of a screw rod, winding carbon fiber filaments around the outer periphery of the glass fiber prepreg on the outer periphery of the screw rod, filling the carbon fiber filaments into the screw thread on the screw rod and fixing, and then laying up carbon fiber prepreg on the surface of the glass fiber prepreg; step 3) curing, manufacturing a curing vacuum bag, and transferring the curing vacuum bag to a hot press tank; and step 4) removing the mold, removing the bottom plate from the bottom first, then rotating and removing the screw rod from the bottom, and obtaining the composite material mounting seat with the inner thread, so that the problems of cost increase caused by air leakage of the embedded thread and difficulty in processing of titanium alloy are solved, economic benefits are improved, and manufacturing cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a method for molding a composite material mounting base. Background Technology

[0002] Threaded connections, as an important connection method, are used in various fields. Currently, most thread materials are metals, such as titanium alloys commonly used in aerospace. Titanium alloys have a very low specific gravity, second only to aluminum, but a hardness similar to steel, and possess excellent heat and cold resistance. Therefore, in aerospace components made of composite materials, integral riveting or pre-embedded titanium alloy threads are commonly used. However, for some aerospace components with aerodynamic requirements, pre-embedded titanium alloy threads obviously cannot meet their airtightness requirements. Even with sealant reinforcement, its use is cautious due to its cumbersome process, increased cost, and potential surface contamination. Integral riveting is expensive due to the difficulty of machining titanium alloys, thus limiting its widespread application. Therefore, we need to use a one-piece molded composite material mounting base with a threaded structure to meet the requirements of both airtightness and economy. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a molding method for a composite material mounting base with an integrally formed internal thread structure, which solves the problems of air leakage due to pre-embedded threads and increased costs caused by difficulties in processing titanium alloys, thereby meeting high airtightness requirements, improving economic efficiency, and reducing manufacturing costs.

[0004] The objective of this invention is achieved as follows: a molding method for a composite material mounting base with an internal thread structure, comprising the following steps:

[0005] Step 1) Prepare the mold, using a male mold structure. The mold includes a screw mounted on the base plate. After cleaning the mold, complete the mold assembly.

[0006] Step 2) Prepreg laying: Fiberglass prepreg is laid on the mold surface, including the base plate surface and the screw surface. Carbon fiber filaments are wrapped around the outer periphery of the fiberglass prepreg on the screw. The carbon fiber filaments are filled into the screw threads and fixed. Then, carbon fiber prepreg is laid on the surface of the fiberglass prepreg.

[0007] Step 3) Curing: Make a curing vacuum bag, transfer it to an autoclave, draw negative pressure from the vacuum bag, fill the autoclave with positive pressure, and run the final curing process according to the curing parameters of the prepreg until it is removed from the autoclave.

[0008] Step 4) Remove the mold. First, remove the base plate from the bottom, and then rotate the screw from the bottom to remove it, thus obtaining a composite mounting base with internal threads.

[0009] As a preferred technical solution of the molding method of the composite material mounting base with an integrally molded internal thread structure according to the present invention, in step 1), the base plate is provided with a mounting hole, the end of the screw connected to the base plate is provided with a threaded hole, the connecting bolt passes through the mounting hole and is screwed into the threaded hole, and the other end of the screw is machined with a hexagonal head.

[0010] As a preferred embodiment of the molding method for the integrally molded composite material mounting base with internal thread structure described in this invention, step 2 specifically includes:

[0011] Step 2-1) Lay fiberglass plain weave prepreg on the mold surface, including the base plate surface and the screw surface, and connect the material sheet at the root of the screw;

[0012] Step 2-2) Wrap carbon fiber filaments around the outer periphery of the glass fiber plain weave prepreg on the outer periphery of the screw, press the carbon fiber filaments into the threads on the screw and fix them;

[0013] Steps 2-3) Lay carbon fiber prepreg in the area on both sides of the screw. Use carbon fiber prepreg to fill the gaps between the laid carbon fiber prepreg and extend it to the screw. Use carbon fiber prepreg with the same fiber direction to fill the gaps between the carbon fiber prepreg on the screw.

[0014] Steps 2-4) Lay a positioning plate on the base plate area. The positioning plate has a circular hole in the center. The circular hole is coaxial with the mounting hole. Then, wrap carbon fiber prepreg around the screw from top to bottom. When laying it on the base plate, the excess prepreg is evenly cut into multiple strips and spread on the base plate area. Cut off the strips outside the circular hole in the center of the positioning plate.

[0015] Steps 2-5) Lay the prepreg in the base plate area. The prepreg has a through hole in the center. The prepreg is inserted into the prepreg by the screw and laid in the prepreg.

[0016] As a preferred technical solution of the molding method of the composite material mounting base with an integrally molded internal thread structure described in this invention, after the carbon fiber prepreg is replenished in step 2-3), the root of the screw is filled with carbon fiber filaments until the required R angle is reached, so that the base plate smoothly transitions to the screw.

[0017] As a preferred technical solution of the molding method of the composite material mounting base with an integrally molded internal thread structure according to the present invention, a vacuum is required after each step 2-1) to 2-5).

[0018] As a preferred technical solution of the molding method of the composite material mounting base with an integrally molded internal thread structure according to the present invention, after each laying of the prepreg in the screw area, the excess prepreg that protrudes above the hexagonal head of the screw end needs to be trimmed off.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention can produce a composite material mounting base with an integrally molded internal thread structure, which can effectively improve the airtightness of the thread, improve the product qualification rate and economic benefits. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0021] Figure 1 This is a flowchart of the present invention.

[0022] Figure 2 This is a schematic diagram of the mold structure in this invention.

[0023] Figure 3 This is an exploded view of the mold used in this invention.

[0024] Figure 4 This is a schematic diagram of the mold coordinate system in this invention.

[0025] Figure 5 This is a schematic diagram of the positioning card plate structure in this invention.

[0026] Figure 6 This is a schematic diagram of the first method of tiling in this invention.

[0027] Figure 7 This is a schematic diagram of the second method of tiling in this invention.

[0028] Figure 8 This is a schematic diagram of the tiling method three in this invention.

[0029] Figure 9 This is a schematic diagram of the fourth method of tiling in this invention.

[0030] Figure 10 This is a schematic diagram of the mounting base obtained by the present invention.

[0031] Among them, 100 is the mold, 101 is the base plate, 102 is the screw, 103 is the connecting bolt, and 200 is the positioning plate. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] like Figure 1 The method for molding a composite material mounting base with an integrally formed internal thread structure is shown. The mounting base is a mounting base for an outer bypass casing of a certain type of engine with an internal thread of M12*1.75L, a taper ratio of 1:16, and a base plate width of 100mm*105mm. It uses two types of prepreg: T800 / B2101 unidirectional prepreg and glass fiber plain weave prepreg. The method includes the following steps:

[0034] Step 1) Preparation, such as Figure 2-4 As shown, a male mold structure is adopted. The mold 100 includes a screw 102 mounted on a base plate 101. The base plate 101 has a mounting hole. One end of the screw 102 connected to the base plate 101 has a threaded hole. A connecting bolt 103 passes through the mounting hole and is screwed into the threaded hole. The other end of the screw 102 is machined with a hexagonal head. After cleaning the mold 100, the assembly of the mold 100 is completed.

[0035] Using a right-handed coordinate system, with the base plate 101 of mold 100 (length 105mm) at 0° and the screw 102 at 0°, design the composite material mounting base blanking drawing and cut the material; lay-up angles should be symmetrically laid up according to the lay-up information table;

[0036] Ply Information Table

[0037]

[0038] Cut a 100mm*105mm release fabric. Using screw 102 as the center and a radius of 37mm, create a positioning plate 200. Figure 5 As shown, it is used to reinforce the position and location;

[0039] Apply high-temperature release agent to mold 100 three or more times (screw 102 is soaked), with an interval of more than 15 minutes between each application. Assemble the mounting base mold 100 using bolts. Place mold 100 on a heating table and heat it to about 70°C.

[0040] Step 2) Laying the tiles. There are four laying methods:

[0041] Method 1: The base plate 101 and the screw 102 are laid separately, and the material sheet is joined at the root of the screw 102;

[0042] Method 2: The base plate 101 and the screw 102 are laid together. The material sheet is divided into 4 pieces. First, the material sheet is laid symmetrically along the edge of the base plate 101. At the gap in the middle, the material sheet is laid from both ends in sequence, up to the root of the screw 102. The excess material is extended upward along the screw 102 as a layer in the 0° direction of the screw 102. The gap in the layer of the screw 102 is filled with material with the same fiber direction.

[0043] Method 3: The base plate 101 is laid together with the screw 102. The prepreg is made of long strips of material, with the short side laid around the outer perimeter of the screw 102, up to the root of the screw 102. The excess material is extended to the base plate 101 and spread evenly. It is cut into multiple thin strips, and the gaps between the thin strips are filled with material sheets. Note that the butt splicing method is used.

[0044] Method 4: Only lay the large surface of the base plate 101 to increase the thickness of the large surface of the base plate 101 to the required thickness.

[0045] When laying layer P1, layer P1 consists of overlapping fiberglass prepreg, using method one. The fiberglass prepreg in area 101 of the base plate is slipped onto screw 102, followed by the fiberglass prepreg around the outer perimeter of screw 102. After laying, it is secured with tape. A non-porous release film, breathable felt, and vacuum bag film are then placed on the surface, connected to a vacuum nozzle. Vacuuming is performed for at least 15 minutes. Figure 6 As shown.

[0046] Open the vacuum bag and tear off approximately 50cm long and 0.5mm wide strips of T800 / B2101 carbon fiber. Wrap the carbon fiber strip around the vacuum-pressed thread, filling it into the root of the thread until it is flush with the crest. Secure the joint of the carbon fiber strip to prevent it from unraveling. Figure 6 As shown.

[0047] Lay the P2 layer, which is T800 / B2101 unidirectional prepreg, using method two for installation, as follows. Figure 7 As shown, after the P2 layer is laid, T800 / B2101 carbon fiber filaments should be used to fill the R angle to R7 at the root of screw 102, seal the pre-extraction bag, and continue to evacuate for more than 15 minutes.

[0048] Apply layer P3, located at the reinforcement + screw 102 location, using method three. Figure 8 As shown, use the positioning plate 200 to position the reinforcement position, trim the excess material pieces that extend beyond the round hole of the plate, and fill in the gaps in the material pieces at the reinforcement position.

[0049] Lay the P10 layer. The P10 layer base plate 101 is made of T800 / B2101 unidirectional prepreg, and is laid using method four. Figure 9 As shown, the prepreg is simply inserted into the screw 102 and laid.

[0050] It should be noted that the specific tiling sequence is P1-P34. P1, P4, P7, P13, P22, P28, P31, and P34 are all laid using Method 1. P2, P6, P8, P1, P27, P29, and P33 are all laid using Method 2. P3, P5, P9, P11, P14, P16, P19, P21, P24, P26, P30, and P32 are all laid using Method 3. P10, P12, P15, P17, P18, P20, P23, and P25 are all laid using Method 4.

[0051] Step 3) After the layup is completed, trim off any excess prepreg that protrudes above the bottom step of the hexagonal head at the end of screw 102 to prevent difficulties in demolding later.

[0052] Step 4) Remove the pre-extracted bag, lay down the high-temperature resistant peelable fabric, lay down the high-temperature resistant isolation film, fill the end of the screw 102 with an appropriate amount of raw silicone to make it round and not easy to burst the bag, then lay down the high-temperature resistant breathable felt, vacuum bag film, place the vacuum nozzle, vacuum and shape it, and check the vacuum bag to ensure that there is no air leakage.

[0053] Step 5) Transport it to the autoclave, vacuum the bag to remove negative pressure, fill the autoclave with positive pressure, and run the final curing process according to the curing parameters of T800 / B2102 until it is discharged from the autoclave.

[0054] Step 6) Remove the connecting bolts 103 and the mounting base plate 101 of the mold 100 in sequence to expose the bottom surface of the composite mounting base. Then carefully unscrew the screw 102 from the hole on the back to obtain a composite mounting base with internal threads. Figure 10 As shown.

[0055] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A molding method for a composite material mounting base with an integrally formed internal thread structure, characterized in that, Includes the following steps: Step 1) Prepare mold (100), adopting a male mold structure. Mold (100) includes a screw (102) installed on the base plate (101). After cleaning the mold (100), the assembly of mold (100) is completed. The base plate (101) mentioned in step 1) has an installation hole. The end of the screw (102) connected to the base plate (101) has a threaded hole. The connecting bolt (103) passes through the installation hole and is screwed into the threaded hole. The other end of the screw (102) is machined with a hexagonal head. Step 2) Prepreg application: Fiberglass prepreg is applied to the surface of the mold (100), including the surface of the base plate (101) and the surface of the screw (102). Carbon fiber filaments are wound around the outer periphery of the fiberglass prepreg on the outer circumference of the screw (102). The carbon fiber filaments are then inserted into the threads on the screw (102) and fixed. Finally, carbon fiber prepreg is applied to the surface of the fiberglass prepreg. Specifically, this includes: Step 2-1) Lay fiberglass plain weave prepreg on the surface of the mold (100), including the surface of the base plate (101) and the surface of the screw (102), and connect the material sheet at the root of the screw (102); Step 2-2) Wrap carbon fiber filaments around the outer periphery of the glass fiber plain weave prepreg on the outer periphery of the screw (102), press the carbon fiber filaments into the threads on the screw (102) and fix them; Steps 2-3) Spread carbon fiber prepreg in the area on both sides of the screw (102). Use carbon fiber prepreg to cover the gaps between the spread carbon fiber prepregs and extend them to the screw (102). Use carbon fiber prepregs with the same fiber direction to fill the gaps between the carbon fiber prepregs on the screw (102). Steps 2-4) A positioning plate (200) is laid on the base plate (101) area. The positioning plate (200) has a circular hole in the center. The circular hole is coaxial with the mounting hole. Then, carbon fiber prepreg is wrapped and laid on the screw (102) from top to bottom. When laying it on the base plate (101), the excess prepreg is evenly cut into multiple strips and spread on the base plate (101) area. The strips outside the circular hole in the center of the positioning plate (200) are cut off. Steps 2-5) The prepreg is laid in the base plate (101) area. A through hole is opened in the center of the prepreg. The prepreg is inserted from the screw (102) and laid in the prepreg. Step 3) Curing: Make a curing vacuum bag, transfer it to an autoclave, draw negative pressure from the vacuum bag, fill the autoclave with positive pressure, and run the final curing process according to the curing parameters of the prepreg until it is removed from the autoclave. Step 4) Remove the mold (100), first remove the bottom plate (101) from the bottom, then rotate and remove the screw (102) from the bottom to obtain a composite material mounting base with internal threads.

2. The molding method of a composite material mounting base with an integrally molded internal thread structure according to claim 1, characterized in that, After the carbon fiber prepreg is replenished in steps 2-3), the root of the screw (102) is filled with carbon fiber filaments until the required R angle is reached, so that the base plate (101) can smoothly transition to the screw (102).

3. The molding method of a composite material mounting base with an integrally molded internal thread structure according to claim 1, characterized in that, After each step from step 2-1) to step 2-5), a vacuum needs to be drawn.

4. The molding method of a composite material mounting base with an internal thread structure as described in claim 1, characterized in that, After each application of the prepreg in the screw (102) area, the excess prepreg that protrudes above the hexagonal head at the end of the screw (102) needs to be trimmed off.

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