A mold and forming method for composite I-beam at special-shaped notch

Abstract

This invention belongs to the field of composite material part forming design, specifically relating to a mold and forming method for a composite material I-beam at an irregular notch. Currently used tooling structures are prone to wrinkling and shape deviations in the fabric layers due to friction between the upper and lower mold layers during mold closing. This invention addresses this issue by providing a groove in the lower mold body for forming the irregular notch. The gap between the first mold and the groove is half the thickness of the part at that location, used for vacuum hot pressing of the lower mold body fabric layers. The gap between the second mold and the groove is the same as the thickness of the part at that location, used for vacuum hot pressing of the combination of the formed lower mold body fabric layers and the unformed upper mold body fabric layers. A mold release groove is provided at the included angle of the groove, and a mold release module is provided on the outer side of the upper end of the lower mold body. The combined upper mold body has a parallel closed-angle surface and a protrusion extending into the groove. This effectively solves the problem of wrinkling caused by friction in the fabric layers during the mold closing process.

Description

Technical Field

[0001] This invention belongs to the field of composite material parts forming design, specifically relating to a mold and forming method for a composite material I-beam at an irregular notch. Background Technology

[0002] Resin-based composite materials have played a crucial role in the rapid development of modern aviation. Their greatest advantages are high specific strength and high specific modulus. Under comparable mass conditions, these materials exhibit high load-bearing capacity, high stiffness, and low deformation. Aviation composite parts are diverse in type and structure, and the types, formation mechanisms, and influencing factors of manufacturing defects are also quite complex. Various defects can arise during the manufacturing process of composite parts due to factors such as environment, raw material defects, process methods, unreasonable structural design, and imperfect molding die structures. The existence of manufacturing defects seriously affects the performance and service life of composite materials, and can even lead to the scrapping of composite parts, causing significant economic losses.

[0003] See also Figure 1 The composite material I-beam in the shown model of a certain aircraft has resin-based composite material components accounting for nearly 50% of the entire machine. The extensive use of composite material components poses unprecedented challenges to the composite manufacturing process. The tail beam is the most important Class I main load-bearing component in the tail assembly. The product has a complex structure, and the overall structure has an I-shaped cross-section along the length direction, as shown in section BB. There is a rectangular through hole at the end of the composite material I-beam. From section AA of the through hole area, it can be seen that the middle of the I-beam in this area forms an irregular notch, and a T-shaped cross-section is formed on both the upper and lower sides of the notch.

[0004] For the current mold design of this irregular notch, please refer to [link / reference]. Figure 2 The upper mold uses a silicone structure, and the side mold uses a metal L-shaped structure, which is mechanically connected to the lower mold. During the layup process, layers are laid on the upper silicone mold and the lower mold respectively. After the layup is completed, the mold is closed, then the side mold is laid up, and finally the side mold is closed.

[0005] The current tooling structure is prone to wrinkles in the fabric layer due to friction between the upper and lower mold layers before the fabric layer is cured, because the thickness of the fabric layer is greater than the theoretical thickness before the mold is closed. Due to the uncontrollable pressure after the silicone is heated, the thickness of the parts will be out of tolerance. The pressure of the silicone on the upper mold will cause the side mold to be squeezed and deformed, resulting in out-of-tolerance issues in the shape of the parts. Summary of the Invention

[0006] The purpose of this invention is to address the problems existing in the current mold-closing process and tooling structure of irregular beams. In order to ensure the forming quality of parts such as thickness and shape, a simple auxiliary compaction tool is used to make the fabric layer reach the theoretical thickness. During the mold-closing process, the protruding part of the upper mold in the irregular area can easily fall into the recessed part of the lower mold, ensuring the mold-closing state of the upper and lower molds. This ensures the internal quality and external dimension requirements of the irregular flange and other parts of the part.

[0007] This invention proposes a mold for a composite material I-beam at an irregular notch. The mold includes a lower mold body, a combined upper mold body, a side mold body, a first pressing mold, a second pressing mold, and an opening module. The lower mold body has a groove for forming the irregular notch. The gap between the first pressing mold and the groove is half the thickness of the part at this location, used for vacuum hot pressing the lower mold body layers. The gap between the second pressing mold and the groove is the same as the thickness of the part at this location, used for vacuum hot pressing the combination of the formed lower mold body layers and the unformed upper mold body layers. An opening groove is provided at the included angle of the groove, and an opening module is provided on the outer side of the upper end of the lower mold body. The combined upper mold body has a parallel closed-angle surface and a protrusion extending into the groove. After assembling the upper mold body, lower mold body, and mold, the side mold body is installed at the outer end.

[0008] Advantageously, the combined upper mold body includes upper mold body one and upper mold body two, and the parting surface of the two has a parallel closed angle surface, and the parallel closed angle surface has a certain angle with the horizontal plane.

[0009] Advantageously, the first and second upper mold bodies have weight-reducing notch structures on the non-forming surfaces.

[0010] Advantageously, the outer surface of the starting module forms part of the mold forming surface.

[0011] Advantageously, the lower mold body has a boss at the bottom of its outer end that supports the side mold body.

[0012] Advantageously, the mold opening groove has a support block that supports the upper mold body of the assembly.

[0013] The present invention also proposes a method for forming the above-mentioned composite material I-beam using a mold at an irregular notch, the method comprising the following steps:

[0014] S1. Lay the lower mold body fabric layer on the lower mold body. After the lower mold body is laid, place the first pressing mold in the groove of the lower mold body and press the vacuum bag with heat.

[0015] S2. Remove the first mold from the groove, lay the mold body cloth layer on the lower mold body, and use a release film to protect the layers of the cloth layer reserved on the edge strip of the upper mold body during laying. Place the second mold in the groove of the lower mold body and make a vacuum bag for room temperature compaction.

[0016] S3. Remove the second mold from the groove, clean the remaining cloth layer at the mold opening groove, and place a raw silicone sheet 1453D at the mold opening groove to block the glue.

[0017] S4. Combine the upper mold body and the lower mold body, and then compact them at room temperature. Then, lay the non-overlapping area of ​​the upper mold body fabric layer protected by the isolation film onto the combined upper mold body. Next, place the twist strips, lay the side mold layers, and then close the side mold body.

[0018] S5. The paste-made vacuum bag is placed in a hot autoclave for curing, and then the mold is opened after curing.

[0019] Advantageously, the hot pressing parameters in S1 are: 65±5℃, constant temperature for 30-40 min, and positive pressure of 0.6 MPa.

[0020] Advantageously, the mold opening process involves first separating the side mold body from the part, then separating the combined upper mold body from the part, and finally detaching the part from the lower mold body through the mold opening module and mold opening groove.

[0021] Beneficial effects:

[0022] 1. The auxiliary compaction tooling effectively solves the wrinkles caused by friction in the fabric layers during the mold closing process;

[0023] 2. Due to the use of auxiliary compaction fixtures, the upper and lower molds can adopt an all-metal structure, effectively avoiding uncontrollable factors of silicone expansion;

[0024] 3. Due to the use of auxiliary compaction fixtures, the side mold shape is changed from L-shaped to an approximately flat plate structure, which simplifies the connection of the side mold. Attached Figure Description

[0025] Figure 1 This is a structural schematic diagram of a certain type of composite material I-beam;

[0026] Figure 2 This is a schematic diagram of the molding die for composite material I-beams at the AA irregular notch.

[0027] Figure 3 This is a schematic diagram of the first-stage molding mold and molding method for the AA-shaped notch of the present invention;

[0028] Figure 4 This is a schematic diagram of the second-stage molding mold and molding method for the AA irregular notch of the present invention;

[0029] Figure 5 This is a schematic diagram of the third-stage molding mold and molding method for the AA irregular notch of the present invention.

[0030] 1-Mold opening slot; 2-Lower mold body; 3-1-Upper mold body one; 3-2-Upper mold body two; 4-Side mold body; 5-First pressing mold; 6-Lower mold body layering; 7-Second pressing mold; 8-Upper mold body layering; 9-Mold opening module Detailed Implementation

[0031] In the mold used in this invention, the lower mold body 2, the combined upper mold body, and the side mold body 4 are the main tooling structures. Both the lower mold body 2 and the combined upper mold body are made of metal, while the side mold body 4 is made of composite material. The combined upper mold body is a split-mold structure, including an upper mold body 1 3-1 and an upper mold body 2 3-2. The split surface has a parallel closed-angle surface to facilitate mold opening. The lower mold body 2 is provided with an opening module 9 and an opening groove 1 to facilitate demolding of the composite material part after curing. Two pressure molds are prepared at the irregular notch. The gap between the first pressure mold 5 and the lower mold body 2 is half the thickness of the part at that location, and the gap between the second pressure mold 7 and the lower mold body 2 is the same as the thickness of the part at that location.

[0032] During molding, the fabric is laid up on the lower mold body 2 according to the part's layup information. During the layup process, the fabric layer is compacted at room temperature every 1-3 layers. After the lower mold body fabric layer 6 is laid up, the first pressure mold 5 is placed in the groove of the irregular notch in the lower mold body 2. A vacuum bag is made for the lower mold body 2, and the lower mold body fabric layer 6 is hot-pressed using an autoclave at a constant temperature of 65±5℃ for 30-40 minutes and a positive pressure of 0.6Mpa. This ensures that the fabric layer of the part laid on the lower mold body 2 in the irregular notch area reaches the theoretical thickness. After compaction, the tooling is cooled to room temperature, and the first pressure mold 5 is removed to continue the subsequent layup.

[0033] According to the part layup information, the existing technology requires the fabric layers to be laid on the upper mold body, which is changed to be laid on the lower mold body 2. For the layup that exceeds the overlapping area of ​​the upper mold body and the lower mold body 2, an isolation film is used to protect each fabric layer. During the layup process, the fabric layers are compacted at room temperature every 1-3 layers. After the fabric layers are laid, the second mold 7 is placed in the groove of the lower mold body 2, and a vacuum bag is made for room temperature compaction.

[0034] After compaction, clean the compressed fabric layer at the mold opening groove 1, and use a raw silicone sheet 1453D to seal the mold opening groove to prevent excessive resin overflow during curing. After the above cleaning and sealing operations are completed, assemble the upper mold body and the lower mold body 2 and close the mold. After closing the mold, in this state, paste a vacuum bag and compact it at room temperature to make the upper mold body and the lower mold body fit together.

[0035] Next, the fabric layers of the non-overlapping areas of the upper mold body, separated by the release film, are laid in reverse and placed into the molding area at the edge of the assembled upper mold body. Then, twist strips are placed, and the fabric layers of the side mold body are laid. The side mold body 4 is then assembled, and a vacuum bag is made and placed in an autoclave for curing.

[0036] The mold opening process after curing involves first separating the side mold body from the part, then separating the combined upper mold body from the part, and finally removing the part from the lower mold body through the mold opening module and mold opening groove.

[0037] The following examples illustrate the layup, compaction, curing, and demolding processes:

[0038] Step 1: Lay the lower mold body fabric layer 6 on the lower mold body 2. After laying, place the first pressing mold 5 in the groove of the irregular notch in the lower mold body 2 to achieve the desired shape. Figure 3 The vacuum bags were then hot-pressed at 65±5℃ for 30-40 minutes with a positive pressure of 0.6 MPa.

[0039] Step 2: Remove the first mold 5 from the groove of the lower mold body 2, and lay the upper mold body fabric layer 8 on the lower mold body 2. During laying, use a release film to protect the layers of the fabric layer reserved on the edge strip of the upper mold body. Place the second mold 7 in the groove of the lower mold body 2 to achieve... Figure 4 The state is then prepared by sealing and sealing in vacuum bags and compacting at room temperature;

[0040] Step 3: Remove the second mold 7 from the irregular notch area of ​​the lower mold body 2, clean the remaining cloth layer at the mold opening groove 1, and place a raw silicone sheet 1453D at the mold opening groove 1 to block the glue.

[0041] Step 4: After assembling the upper mold body 3-1 and the upper mold body 3-2, close them with the lower mold body 2. After closing, compact at room temperature. Then, reverse the non-overlapping areas of the upper mold body fabric layer 8 (protected by the release film) onto the assembled upper mold body. Subsequently, place the twist strips, lay the side mold layers, and close the side mold body 4 to achieve the desired effect. Figure 5 state;

[0042] Step 5: The vacuum bag is put into a thermostatic jar for curing. After curing, the mold opening process is to first separate the side mold body 4 from the part, then separate the combined upper mold body 3 from the part, and then remove the part from the lower mold body 2 through the opening module 9 and the opening groove 1.

Claims

1. A mold for a composite material I-beam at an irregularly shaped notch, characterized in that: The mold includes a lower mold body (2), an upper mold body, a side mold body (4), a first pressure mold (5), a second pressure mold (7), and an opening module (9). The lower mold body (2) has a groove for forming irregular notches. The gap between the first pressure mold (5) and the groove is half the thickness of the part at this position, which is used for vacuum hot pressing of the lower mold body layer (6). The gap between the second pressure mold (7) and the groove is the same as the thickness of the part at this position, which is used for vacuum hot pressing of the combination of the formed lower mold body layer (6) and the unformed upper mold body layer (8). An opening groove (1) is provided at the included angle of the groove, and an opening module (9) is provided on the outer side of the upper end of the lower mold body (2). The upper mold body has a parallel closed angle surface and a protrusion extending into the groove. After the upper mold body and the lower mold body (2) are combined, the side mold body (4) is installed at the outer end.

2. The mold for the composite material I-beam at the irregular notch according to claim 1, characterized in that: The combined upper mold body includes upper mold body one (3-1) and upper mold body two (3-2). The parting surfaces of the two have parallel closed angle surfaces, and the parallel closed angle surfaces have a certain angle with the horizontal plane.

3. The mold for the composite material I-beam at the irregular notch according to claim 2, characterized in that: The upper mold body one (3-1) and upper mold body two (3-2) have weight-reducing notch structures on the non-forming surface.

4. The mold for the composite material I-beam at the irregular notch according to claim 1, characterized in that: The outer surface of the starting module (9) constitutes part of the mold forming surface.

5. The mold for the composite material I-beam at the irregular notch according to claim 1, characterized in that: The lower mold body (2) has a boss at the bottom of its outer end that supports the side mold body (4).

6. The mold for the composite material I-beam at the irregular notch according to claim 1, characterized in that: The mold opening groove (1) has a support block that supports the upper mold body.

7. A method for forming a composite material I-beam at an irregular notch using a mold as described in any one of claims 1-6, characterized in that, The method includes the following steps: S1. Lay the lower mold body fabric layer (6) on the lower mold body (2). After the laying is completed, place the first pressing mold (5) in the groove of the lower mold body (2) and press the vacuum bag with heat. S2. Take the first mold (5) out of the groove, and lay the mold body cloth layer (8) on the lower mold body (2). When laying, use an isolation film to protect the layers of the cloth layer reserved on the upper mold body edge strip. Place the second mold (7) in the groove of the lower mold body (2) and make a vacuum bag for room temperature compaction. S3. Remove the second mold (7) from the groove, clean the remaining cloth layer at the mold opening groove (1), and place a raw silicone sheet 1453D at the mold opening groove (1) to block the glue. S4. Combine the upper mold body and the lower mold body (2) and then compact them at room temperature. Then, lay the non-overlapping area of ​​the upper mold body fabric layer (8) protected by the isolation film onto the combined upper mold body. Then, place the twist strips, lay the side mold layer, and then close the side mold body (4). Step 5: Place the paste-made vacuum bag into an autoclave for curing, and then open the mold after curing.

8. The method for forming the composite material I-beam at the irregular notch using a mold according to claim 7, characterized in that: The hot pressing parameters in S1 are: 65±5℃, constant temperature for 30-40 min, and positive pressure of 0.6Mpa.

9. The method for forming the composite material I-beam at the irregular notch using a mold according to claim 7, characterized in that: The mold opening process involves first separating the side mold body (4) from the part, then separating the combined upper mold body from the part, and finally removing the part from the lower mold body (2) through the mold opening module (9) and the mold opening groove (1).

Images