A method of forming a thin-walled composite shell by adhesive bonding

Abstract

The application discloses a kind of thin-walled composite material shell set bonding forming method in the technical field of composite material product, and thin-walled composite material shell includes metal piece in inner layer and composite piece in outer layer, metal piece and composite piece are both cylinder structure, the top end of metal piece is open, bottom is closed, and through hole is processed on the side wall of metal piece, comprising the following steps: step 1) metal piece installation support tooling, step 2) metal piece outer surface protection, step 3) composite piece installation set tooling, step 4) composite piece sets metal piece bonding, step 5) product stripping disassembly, the present application solves the problem that thin-walled part is shaped in the process of composite forming and supporting core mold tooling stripping disassembly is difficult.

Description

Technical Field

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

[0002] In the 21st century, engine casings are the primary power output structures for various rockets and missiles, widely used in the aerospace field. To improve product performance, weight control is crucial; therefore, thin-walled structural parts are increasingly chosen for engine casings. To ensure the dimensional accuracy of thin-walled composite material casings, current technologies primarily involve winding composite fibers onto metal structural parts, followed by machining of the inner walls of the metal parts and the outer walls of the composite cylinder to guarantee dimensional accuracy. However, with the continuous evolution of engine casing models and structures, the diverse internal cavities of the metal, including complex structures such as grooves, make the molding of composite material casings increasingly difficult. Maintaining shape during the molding of thin-walled composite material casings remains a significant technical challenge in the industry. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for bonding and molding thin-walled composite material shell sets, solving the problems of shape preservation and disassembly of support core molds for thin-walled parts during composite molding.

[0004] The objective of this invention is achieved as follows: a method for bonding and molding a thin-walled composite material shell assembly, wherein the thin-walled composite material shell includes an inner metal component and an outer composite component, both of which are cylindrical structures. The top end of the metal component is open and the bottom end is closed, and through holes are machined on the sidewalls of the metal component. The method includes the following steps: Step 1) Install the support fixture on the metal part and install the support fixture inside the inner cavity of the metal part so that the support fixture fits against the inner cavity wall of the metal part. Step 2) Protect the outer surface of the metal part. Attach release cloth to both ends of the metal part for protection. Cut silicone pads of the corresponding size to the through holes on the metal part, wrap the release cloth completely, and insert it into the through holes on the metal part. Step 3) Assemble the composite parts with the tooling kit. Before assembly, the inner surface of the tooling kit must be ground to ensure that the outer cover can be installed into the tooling kit and fit completely in place. Step 4) Bonding composite parts to metal parts: Pre-assemble the composite parts to ensure they can be properly fitted using the fitting fixture. Then remove the fitting fixture and composite parts. Apply adhesive evenly to the outer surface of the metal parts. Fit the composite parts using the fitting fixture, pressing down with the fixture's own weight and gently tapping the fixture with a rubber mallet to fit the composite parts into place. Move the product along with the fixture into the oven for curing. Step 5) Demolding and disassembling the product: First, remove the kit, then remove the support kit to obtain the thin-walled composite material shell.

[0005] As a further limitation of the present invention, the supporting fixture in step 1) includes: The slider assembly includes multiple first sliders and multiple second sliders. The first sliders and second sliders can be spliced ​​together at intervals to form a complete cylinder, and a through hole is formed inside. The two ends of the through hole are tapered holes. A tensioning washer assembly is provided inside the slider assembly, including two circular washers. The two circular washers are connected in series by a screw assembly. The outer periphery of the two circular washers is machined into a tapered surface that mates with the tapered hole. The distance between the two circular washers is adjusted by the screw assembly to open the slider assembly. A ring pad is provided at the end of the slider assembly. The ring pad consists of two semi-rings that can be spliced ​​together to form a complete circular ring. Step 1) Specifically: First, insert the ring washer into the bottom groove of the metal part. Then, place the series-connected screw assembly and tension washer set on the upper side of the ring washer. Next, place the first slider and the second slider into the metal part at intervals around the screw assembly. Adjust the position of the first slider and the second slider and simultaneously drive the tension washer set into the conical holes formed at both ends of the first slider and the second slider through the screw assembly. Finally, adjust the distance between the two circular washers to open the slider assembly and fit it against the inner surface of the metal part, so that the slider assembly supports the metal part.

[0006] As a further limitation of the present invention, in step 2), when the release cloth is pasted, the release cloth shall not protrude from the outer surface of the metal part; the through hole is opened on the side wall; the outer periphery of the top of the metal part is also provided with multiple countersunk holes, the release cloth is pasted and sealed in the countersunk holes, the silicone pad and the release cloth shall not protrude from the outer surface of the metal part, the metal part is put into the guide post of the kit base and fixed, and it is confirmed that the bottom surface of the metal part is in close contact with the kit base.

[0007] As a further limitation of the present invention, the kit in step 3) includes two semi-cylinders that can be assembled into a cylindrical structure. The two semi-cylinders are positioned and connected by a cylindrical pin. The outer periphery of the two semi-cylinders is machined into three sections of circumferential surfaces with different diameters. The circumferential surfaces are connected by an inclined surface. Two tooling rings are fitted on the inclined surface of the outer periphery of the two semi-cylinders to clamp the two semi-cylinders after assembly. Step 3) Specifically: After grinding the inner surface of one half-cylinder, fit it onto one side of the composite part. Then, after grinding the inner surface of the other half-cylinder, fit it onto the other side of the composite part. Position and splice the two half-cylinders together with cylindrical pins. Finally, fit the two tooling rings into the tooling and lock the tooling in place.

[0008] As a further limitation of the present invention, step 5) specifically includes: taking out the two tooling rings in sequence, removing the two semi-cylinders, operating to loosen the screw assembly inside the metal part, gently tapping and vibrating the screw assembly downwards to cause the tension washer assembly to disengage from the slider and fall to the bottom, the slider assembly will disperse and separate from each other, and finally removing the screw assembly, slider assembly, tension washer assembly, and ring washer from the metal part to complete the shell forming. Compared with the prior art, the beneficial effects of the present invention are as follows: the method of the present invention can effectively support and protect the complex internal cavity of the metal part, and simplifies the installation and disassembly method of the internal support mold of the metal part. The composite outer cylinder assembly tooling can effectively maintain the outer contour of the cylinder during the shell forming process. Attached Figure Description

[0009] 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.

[0010] Figure 1 This is a flowchart of the present invention.

[0011] Figure 2 This is a schematic diagram of the thin-walled composite material shell structure in this invention.

[0012] Figure 3 This is a cross-sectional view of the thin-walled composite material shell in this invention.

[0013] Figure 4 This is a schematic diagram of the supporting tooling structure in this invention.

[0014] Figure 5 This is a cross-sectional view of the supporting tooling in this invention.

[0015] Figure 6 This is a schematic diagram of the tooling structure in this invention.

[0016] Figure 7 This is a cross-sectional view of the tooling assembly used in this invention.

[0017] Figure 8 This is a schematic diagram of the assembly cross-section of the present invention.

[0018] Among them, 100 is the slider assembly, 101 is the first slider, 102 is the second slider, 200 is the tensioning washer assembly, 201 is the first washer, 202 is the second washer, 300 is the ring washer, 301 is the half ring, 400 is the screw assembly, 401 is the screw, 402 is the nut, 500 is the sleeve assembly, 501 is the semi-cylinder, 502 is the tapered pin, 600 is the tooling ring, 700 is the thin-walled composite material housing, 701 is the metal part, 701a is the groove, 702 is the composite part, 703 is the waist-shaped hole, and 704 is the countersunk hole. Detailed Implementation

[0019] 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.

[0020] A method for bonding and molding a thin-walled composite material shell assembly, such as Figure 2-3 The thin-walled composite material shell 700 shown includes a metal part 701 located in the inner layer and a composite material part 702 located in the outer layer. The metal part 701 and the composite material part 702 are fitted together. Both the metal part 701 and the composite material part 702 are cylindrical structures. The top of the metal part 701 is open and the bottom is closed. The bottom of the metal part 701 is also provided with a groove 701a. The side wall of the metal part 701 is machined with a waist-shaped hole 703. Because the thin-walled composite material shell 700 is too thin, it is particularly easy to deform locally due to uneven stress during the molding process.

[0021] To address the deformation problem, the molding method of this invention uses a tooling assembly, including a support tooling and a fitting tooling, wherein... like Figure 4-5 As shown, the support fixture includes: The slider assembly 100 includes a plurality of first sliders 101 and a plurality of second sliders 102. The first sliders 101 and the second sliders 102 can be spliced ​​together at intervals to form a complete cylinder, and a through hole is formed inside, with tapered holes at both ends of the through hole. A tensioning washer assembly 200 is disposed inside the slider assembly 100 and includes two circular washers, namely a first washer 201 and a second washer 202. The first washer 201 and the second washer 202 are connected in series via a screw assembly 400. The outer periphery of the first washer 201 and the second washer 202 is machined into a tapered surface that mates with a tapered hole in the slider assembly 100. The distance between the first washer 201 and the second washer 202 is adjusted by the screw assembly 400 to open the slider assembly 100. The screw assembly 400 includes a screw 401 connected in series with the first washer 201 and the second washer 202. The screw 401 is threaded to the second washer 202. The screw 401 passes through the first washer 201 and a nut 402 is threaded on the outside of the first washer 201. The screw 401 is an M10 screw 401 and the nut 402 is also an M10 nut 402. The ring pad 300 is located at one end of the slider assembly 100 and consists of two half rings 301, which can be spliced ​​together to form a complete circular ring.

[0022] Specifically, in this embodiment, a total of four first sliders 101 and four second sliders 102 are used. The size of the first sliders 101 is larger than that of the second sliders 102. The outer surface of the whole cylinder formed by splicing the first sliders 101 and the second sliders 102 can be completely supported on the inner wall of the metal part 701. The tensioning pad group 200 supports the first sliders 101 and the second sliders 102. The ring pad 300 is placed in the groove 701a at the bottom of the thin-walled metal part 701 of the product and supports the shape of the groove 501 of the thin-walled metal part.

[0023] like Figure 6-7 As shown, the tooling kit includes: The sleeve assembly 500 is assembled from two semi-cylinders 501. The mating surface is provided with two pairs of ø8mm pin holes, into which ø8×20 internal thread cylindrical pins 502 can be inserted for limiting connection. The inner surfaces of the two semi-cylinders 501 are completely fitted with the outer surface of the composite part 702, which can completely wrap the composite part 702 to prevent the composite part 702 from deforming under internal pressure. The outer periphery of the sleeve assembly 500 is machined into three circumferential surfaces of different diameters, and the circumferential surfaces are transitioned by inclined surfaces. There are two tooling rings 600. The inner surfaces of the two tooling rings 600 are tapered. They are respectively fitted onto the two inclined transition sections of the sleeve assembly 500. After the two semi-cylinders 501 are assembled, the two tooling rings 600 can be sequentially fitted into the outer tapered surface of the sleeve assembly 500 and pushed tightly towards the bottom of the tooling assembly to completely limit and fix the two semi-cylinders 501.

[0024] like Figure 1 , 8 The method for bonding and molding a thin-walled composite material shell 700 assembly, as shown, includes the following steps: Step 1) Install the support fixture on the metal part 701; first, insert the semi-ring 301 pad 300 into the bottom groove 701a of the metal part 701, then screw the M10 screw 401 into the center M10 threaded hole of the second washer 202 of the tensioning washer assembly 200, then place the integrated M10 screw 401 and the second washer 202 of the tensioning washer assembly 200 on the upper side of the semi-ring 301 pad 300, then sequentially insert each first slider 101 and second slider 102 around the periphery of the M10 screw 401 into the inner cavity of the metal part 701, and adjust the first slider 101 and second slider 102. The slider 102 is positioned and simultaneously driven by the M10 screw 401 to engage the second washer 202 of the tensioning washer assembly 200 into the tapered step at the bottom of the first slider 101 and the second slider 102. Finally, the first washer 201 of the tensioning washer assembly 200 is fitted onto the upper part of the M10 screw 401, and the M10 nut 402 is screwed into the upper end of the first washer 201 of the tensioning washer assembly 200 along the M10 screw 401. The M10 nut 402 drives the tensioning washer assembly 200 to tighten towards each other, thereby causing the first slider 101 and the second slider 102 to move outward and press against the inner cavity of the thin-walled metal part.

[0025] The purpose of this step is to ensure that the metal part 701 does not deform under external pressure during the molding process by fitting the outer surface of the supporting fixture to the inner wall of the supporting metal part 701. Specifically, the semi-ring 301 pad 300 is positioned within the annular cavity at the bottom of the metal part 701 under the bottom limiting of the first slider 101 and the second slider 102, thus supporting the inner cavity at the bottom of the metal part 701. The first slider 101 and the second slider 102 expand outwards under the action of the conical surface of the tensioning washer group 200, ensuring that their side end faces fit and are limited, ultimately allowing the outer surfaces of the first slider 101 and the second slider 102 to be joined to form a complete cylindrical surface, supporting the cylindrical inner cavity of the metal part 701. The tensioning washer group 200 is pressed together under the tightening force of the M10 nut 402 and the M10 screw 401, supporting the first slider 101 and the second slider 102 to form a complete cylindrical surface.

[0026] Step 2) Protect the outer surface of metal part 701; attach release cloth to the bottom and top of metal part 701 for protection. Note that the release cloth should not protrude from the outer surface of metal part 701 to avoid forming a sandwich when installing composite part 702. Cut silicone pads of appropriate size and wrap them with release cloth. Insert them into the two waist-shaped holes 703 on the side wall of metal part 701. Attach release cloth to the six countersunk holes 704 on the top of metal part 701 to seal them and prevent adhesive from flowing into the inner cavity. Note that the silicone pads and release cloth should not protrude from the outer surface of metal part 701 to avoid forming a sandwich when installing composite part 702. Place metal part 701 onto the ∅45 guide post of the mounting base and fix it in place. Confirm that the bottom surface of metal part 701 is firmly attached to the mounting base.

[0027] The purpose of this step is to protect the non-bonding surfaces of the metal part 701 before bonding, ensuring that the non-bonding surfaces of the product are clean and free of adhesive residue after bonding. Specifically, a release cloth is bonded to the bottom and top of the metal part 701 to ensure that there is no residual adhesive on the bottom and top of the metal part 701; silicone pads are inserted into the two oblong holes 703 of the metal part 701 to prevent adhesive from entering the inner cavity of the metal part 701; the metal part 701 is fitted onto the mounting base to ensure that the metal part 701 is stable and does not shift during fitting.

[0028] Step 3) Install the composite part 702 into the fixture; assemble the composite part 702 with the single-sided semi-cylinder 501, and lightly grind the inner surface of the single-sided semi-cylinder 501 to ensure that the composite part 702 can be installed into the fixture and check that it fits perfectly at the corner of the conical surface; repeat the above operation to assemble the composite part 702 with the other side semi-cylinder 501; fit the fixture onto the outside of the fitted composite part 702, and position and splice the two semi-cylinders 501 together using two GB / T120.2 ∅8*20 internal thread cylindrical pins. Finally, install the two fixture rings 600 into the outside of the sleeve assembly 500 and lock the sleeve assembly 500 in place.

[0029] The purpose of this step is to attach and press the tooling together with the outer wall of the composite part 702 to ensure that the composite part 702 does not deform under the internal pressure during the product molding process. Specifically, the two locating pin holes on the sides of the two semi-cylinders can accommodate GB / T120.2 ∅8*20 internal thread cylindrical pins to ensure the relative positional accuracy of the semi-cylinders and to form a complete cylinder; the two tooling rings 600 can be fitted onto the outside of the sleeve assembly 500 and pressed tightly against the outer surface of the sleeve assembly 500, ensuring that the sleeve assembly 500 is locked in place and the entire cylinder remains undeformed.

[0030] Step 4) Bonding composite component 702 to metal component 701; Pre-assemble composite component 702, confirming that it can be properly assembled using the assembly tooling (the bottom of the assembly tooling is 15mm from the top plane of the assembly base). Then remove the assembly tooling and composite component 702, prepare the bonding adhesive, and apply the adhesive evenly to the outer surface of the metal component 701, ensuring a thick coating without any missed areas; Assemble composite component 702 using the assembly tooling, pressing down with the tooling's own weight and gently tapping it with a rubber hammer to assemble the composite component 702 into place. The bottom of the assembly tooling should be 15mm from the assembly base. Move the product along with the assembly into the oven for curing. Curing regime: heating rate 1℃ / minute, heating to 80℃ and holding for 4 hours.

[0031] The purpose of this step is to bond the composite part 702 to the metal part 701 in place and ensure that the internal and external contours of the product remain unchanged. The fixture with the composite part 702 already installed can evenly fit the composite part 702 onto the outer wall of the metal part 701, and its own weight ensures that the composite part 702 is pressed into place. The fixture base effectively fixes the metal part 701, ensuring that the metal part 701 does not shift during the assembly process. The proper assembly of the composite part 702 can be ensured by measuring 15mm from the bottom of the fixture to the top plane of the fixture base.

[0032] Step 5) Product demolding and disassembly; take out the two tooling rings 600 in sequence, pry out the two semi-cylinders 501 through the demolding groove, loosen the M10 nut 402 on the inside of the metal part 701 to separate the first washer 201 and M10 screw 401 from the tensioning washer group 200, tap and vibrate the M10 screw 401 downwards to make the second washer 202 of the tensioning washer group 200 separate from the first slider 101 and the second slider 102 and fall to the bottom, then pry the first washer 201 of the tensioning washer group 200 to separate it from the first slider 101 and the second slider 102. The first slider 101 and the second slider 102 will separate from each other. At this point, the first washer 201, the first slider 101, the second slider 102, the second washer 202, the M10 screw 401 and the semi-ring 301 washer 300 can be taken out from the inner cavity of the thin-walled metal part 701 in sequence. At this point, the shell forming is completed.

[0033] The purpose of this step is to demold the solidified product. Specifically, removing the two tooling rings 600 from the two semi-cylinders removes the external locking force on the semi-cylinders 501. Then, by prying and disassembling the semi-cylinders through the demolding grooves, the tooling semi-cylinders 501 can be removed without damaging the outer wall of the composite material 702. Disassembling and removing the M10 screw 401 and nut 402 loosens the internal support force of the tensioning washer, ensuring that the tensioning washer assembly 200 can disassemble from the inside of the metal part 701 without external impact. After the tensioning washer assembly 200 separates, the first slider 101 and the second slider 102 can be slightly pried to disassemble and detach from the inner cavity of the metal part 701, ensuring that the first slider 101 and the second slider 102 can be disassembled without damaging the inner cavity of the metal part 701. Finally, the semi-ring 301 pad 300 can be easily tilted, completing the demolding process.

[0034] 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 method for bonding and molding a thin-walled composite material shell assembly, wherein the thin-walled composite material shell (700) includes a metal part (701) located in the inner layer and a composite material part (702) located in the outer layer, both the metal part (701) and the composite material part (702) are cylindrical structures, the top end of the metal part (701) is open and the bottom end is closed, and through holes are machined on the side wall of the metal part (701), characterized in that, Includes the following steps: Step 1) Install the support fixture on the metal part (701). Complete the installation of the support fixture inside the cavity of the metal part (701) so that the support fixture fits against the inner wall of the metal part (701). Step 2) Protect the outer surface of the metal part (701). Attach release cloth to both ends of the metal part (701) for protection. Cut silicone pads of the corresponding size to the through holes on the metal part (701), wrap the release cloth completely, and insert it into the through holes on the metal part (701). Step 3) Install the composite part (702) with the tooling. Assemble the composite part (702) with the tooling. Before assembly, the inner surface of the tooling needs to be ground to ensure that the outer cover can be installed into the tooling and fit completely in place. Step 4) Bond the composite part (702) to the metal part (701). Pre-fit the composite part (702) and confirm that the composite part (702) can be fitted into place using the fitting fixture. Then remove the fitting fixture and the composite part (702). Apply adhesive evenly to the outer surface of the metal part (701). Fit the composite part (702) into place using the fitting fixture. Press down with the fixture's own weight and gently tap the fitting fixture with a rubber hammer to fit the composite part (702) into place. The product was moved into the oven along with the tooling for curing. Step 5) Demolding and disassembling the product: First, remove the kit, then remove the support kit to obtain the thin-walled composite material shell (700). The support fixture mentioned in step 1) includes: The slider assembly (100) includes a plurality of first sliders (101) and a plurality of second sliders (102). The first sliders (101) and the second sliders (102) can be spliced ​​together at intervals to form a complete cylinder, and a through hole is formed inside, with tapered holes at both ends of the through hole. A tensioning washer assembly (200) is provided inside the slider assembly (100) and includes two circular washers. The two circular washers are connected in series by a screw assembly (400). The outer periphery of the two circular washers is machined into a tapered surface that matches the tapered hole. The distance between the two circular washers is adjusted by the screw assembly (400) to open the slider assembly (100). A ring pad (300) is provided at the end of the slider assembly (100). The ring pad (300) is composed of two half rings (301) that can be spliced ​​together to form a complete circular ring. Step 1) Specifically: First, insert the ring washer (300) into the bottom groove (701a) of the metal part (701). Then, place the series-connected screw assembly (400) and tension washer set (200) on the upper side of the ring washer (300). Then, place the first slider (101) and the second slider (102) around the screw assembly (400) and place them at intervals into the metal part (701). Adjust the position of the first slider (101) and the second slider (102) and at the same time, drive the tension washer set (200) through the screw assembly (400) to be inserted into the conical holes formed at both ends of the first slider (101) and the second slider (102). Finally, adjust the distance between the two circular washers to open the slider assembly (100) and fit it against the inner surface of the metal part (701), so that the slider assembly (100) supports the metal part (701). The tooling set described in step 3) includes two semi-cylinders (501) that can be assembled into a cylindrical structure. The two semi-cylinders (501) are positioned and connected by cylindrical pins. The outer circumference of the two semi-cylinders (501) is machined into three sections of circumferential surfaces with different diameters. The circumferential surfaces are connected by inclined surfaces. Two tooling rings (600) are fitted on the inclined surfaces of the outer circumference of the two semi-cylinders (501) to clamp the two semi-cylinders (501) after assembly. Step 3) Specifically: After grinding the inner surface of one half-cylinder (501), it is fitted onto one side of the composite part (702). Then, after grinding the inner surface of the other half-cylinder (501), it is fitted onto the other side of the composite part (702). The two half-cylinders (501) are positioned and spliced ​​together by cylindrical pins. Finally, the two tooling rings (600) are fitted in to lock the tooling. Step 5) specifically includes: taking out the two tooling rings (600) in sequence, removing the two half cylinders (501), operating to loosen the screw assembly (400) inside the metal part (701), gently tapping and vibrating the screw assembly (400) downwards to make the tensioning washer group (200) detach from the slider and fall to the bottom, the slider assembly (100) will disperse and detach from each other, and finally removing the screw assembly (400), slider assembly (100), tensioning washer group (200), and ring washer (300) from the metal part (701) to complete the shell forming.

2. The method for bonding and molding a thin-walled composite material shell assembly according to claim 1, characterized in that, In step 2), when pasting the release cloth, the release cloth must not protrude from the outer surface of the metal part (701); the through hole is opened on the side wall; the outer periphery of the top of the metal part (701) is also provided with multiple countersunk holes (704), the release cloth is pasted and sealed in the countersunk holes (704), the silicone pad and the release cloth must not protrude from the outer surface of the metal part (701), the metal part (701) is put into the guide post of the kit base and fixed, and it is confirmed that the bottom surface of the metal part (701) is in close contact with the kit base.

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