Mold and forming method for composite material I beam at special-shaped notch

Abstract

The invention belongs to the field of composite material part forming design, and particularly relates to a mold and a forming method for a composite material I beam at a special-shaped notch. A tool structure adopted at present has the problems of wrinkles and out-of-tolerance appearance of cloth layers caused by friction of the cloth layers of an upper mold and a lower mold in the mold closing process. The lower die body is provided with the groove for forming the special-shaped notch, the value of the gap between the first pressing die and the groove is 1 / 2 of the thickness of a part at the position, and the first pressing die is used for conducting vacuum hot press forming on a cloth layer of the lower die body; the value of a gap between the second pressing die and the groove is consistent with the thickness of the part at the position, and the second pressing die is used for carrying out vacuum hot press forming on a combination of the formed lower die body cloth layer and the unformed upper die body cloth layer; a mold opening groove is formed in the included angle of the groove; a mold opening block is arranged on the outer side of the upper end of the lower mold body; and the combined upper die body is provided with a parallel closed angle surface and a convex block extending into the groove. And wrinkles caused by friction of the cloth layer in the upper and lower mold closing process are effectively solved.

Description

Technical Field

[0001] The invention belongs to the field of composite material part forming design, and in particular relates to a mold and a forming method for a composite material I-beam at a special-shaped notch. Background Art

[0002] Resin-based composite materials have played a pivotal role in the rapid development of modern aviation. The biggest advantages of resin-based composite materials are high specific strength and high specific modulus. Under the condition of equivalent mass, the material has large load-bearing capacity, high stiffness and small deformation. There are many types of aviation composite parts and various structural forms. The types of manufacturing defects, formation mechanisms and influencing factors are also relatively complex. In the manufacturing process of composite parts, various defects will occur due to factors such as environment, raw material defects, process methods, unreasonable structural design and imperfect molding mold structure. The existence of manufacturing defects seriously affects the performance and service life of composite materials, and may even lead to the scrapping of composite parts, causing significant economic losses.

[0003] See also Figure 1 The composite I-beam in a certain type of machine shown in the figure, in which resin-based composite parts account for nearly 50% of the entire machine. The use of a large number of composite parts has brought unprecedented challenges to the composite manufacturing process. The vertical tail beam is the most important Class I main load-bearing component in the vertical tail assembly. The product structure is complex, and the overall structure has an I-shaped section in the length direction. As shown in the BB section, there is a rectangular through hole at the end of the composite I-beam. From the AA section of the through hole area, it can be seen that the middle of the I-beam in this area forms a special-shaped notch, and a T-shaped section is formed on the upper and lower sides of the notch.

[0004] For the current mold design of this special-shaped notch, see Figure 2 The upper mold uses a silicone structure, the side mold uses a metal L-shaped structure, and is mechanically connected to the lower mold. When laying the layers, the layers are laid on the upper mold silicone and the lower mold respectively. After laying the layers, the molds are closed, and then the side molds are laid, and finally the side molds are closed.

[0005] The tooling structure currently used has a thickness greater than the theoretical thickness before the cloth layer is solidified, so friction between the upper and lower mold cloth layers is prone to occur during the mold closing process, causing wrinkles in the cloth layer; the uncontrollable problem of pressurization after the silicone is heated up will cause the thickness of the parts to be out of tolerance, and the pressurization of the silicone on the part mold will cause the side mold to be squeezed and deformed, resulting in out-of-tolerance problems in the shape of the parts. Summary of the invention

[0006] The purpose of the present invention is to address the problems existing in the existing mold closing process and tooling structure of special-shaped beams, and to ensure the forming quality of the thickness, shape and other aspects of the parts. By using a simple auxiliary compaction tooling, the cloth layer reaches the theoretical thickness state, and the protruding position of the upper mold in the special-shaped area can easily fall into the recessed position of the lower mold during the mold closing process, ensuring the mold closing state of the upper and lower molds, thereby ensuring the internal quality and outer dimension requirements of the parts at the special-shaped flanging position and other positions of the parts.

[0007] The present invention proposes a mold for a composite material I-beam at a special-shaped notch, the mold comprising a lower mold body, a combined upper mold body, a side mold body, a first die, a second die and an opening module, wherein the lower mold body has a groove for forming the special-shaped notch, the gap value between the first die and the groove is 1 / 2 of the thickness of the part at this position, and is used for vacuum hot pressing the lower mold body cloth layer; the gap value between the second die and the groove is consistent with the thickness of the part at this position, and is used for vacuum hot pressing the combination of the formed lower mold body cloth layer and the unformed upper mold body cloth layer; an opening mold groove is provided at the angle of the groove, and an opening module is arranged on the outer side of the upper end of the lower mold body; the combined upper mold body has parallel closed angle surfaces and a protrusion extending into the groove; after the upper mold body and the lower mold body and the mold are combined, the side mold body is installed at the outer end.

[0008] Advantageously, the combined upper mold body comprises an upper mold body 1 and an upper mold body 2, and 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.

[0009] Advantageously, the upper mold body 1 and the upper mold body 2 have a weight-reducing notch structure on the non-molding surface.

[0010] Advantageously, the outer profile of the starter module forms part of the molding surface of the mold.

[0011] Advantageously, the lower mold body has a boss at the bottom of the outer end for supporting the side mold body.

[0012] Advantageously, a support block for supporting the combined upper mold body is provided in the mold opening groove.

[0013] The present invention also provides a method for forming the composite I-beam using a mold at a special-shaped notch, the method comprising the following steps:

[0014] S1, laying the lower mold cloth layer on the lower mold, placing the first pressing mold in the groove of the lower mold after the laying is completed, and pasting the vacuum bag for hot compaction;

[0015] S2, taking out the first die from the groove, laying the upper die cloth layer on the lower die, using an isolation film to protect the layers of the upper die edge strip reserved for the cloth layer, placing the second die in the groove of the lower die, and pasting a vacuum bag for room temperature compaction;

[0016] S3, taking the second die out of the groove, cleaning the remaining cloth layer at the die opening groove, and placing a raw silicone sheet 1453D at the die opening groove to block the glue;

[0017] S4, closing the combined upper mold body and the lower mold body, compacting them at room temperature after closing the mold, laying the cloth layer of the non-overlapping area of ​​the upper mold body protected by the isolation film on the combined upper mold body, subsequently placing the twist strip, laying the side mold layer, and closing the side mold body;

[0018] S5. Put the pasted vacuum bag into the autoclave for curing, and open the mold after curing.

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

[0020] Advantageously, the demolding process is to first separate the side mold body from the part, then separate the combined upper mold body from the part, and then detach the part from the lower mold body through the demolding module and the demolding groove.

[0021] Beneficial effects:

[0022] 1. The use of auxiliary compaction tooling can effectively solve the wrinkles on the fabric layer caused by friction during the clamping process of the upper and lower molds;

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

[0024] 3. Due to the use of auxiliary compaction tooling, the side form is changed from L-shaped to a nearly flat plate structure, making the side form connection simple. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0026] Figure 2 It is a schematic diagram of the forming die of the current composite I-beam at the AA special-shaped notch;

[0027] Figure 3 It is a schematic diagram of the first stage forming mold and forming method of the present invention at the AA special-shaped notch;

[0028] Figure 4 It is a schematic diagram of the second stage forming die and forming method at the AA special-shaped notch of the present invention;

[0029] Figure 5 It is a schematic diagram of the third stage forming mold and forming method at the AA special-shaped notch of the present invention.

[0030] 1- opening die groove; 2- lower die body; 3-1- upper die body 1; 3-2- upper die body 2; 4- side die body; 5- first die; 6- lower die body cloth layer; 7- second die; 8- upper die body cloth layer; 9- opening die block DETAILED DESCRIPTION

[0031] In the mold used in the example of the present invention, the lower mold body 2, the combined upper mold body and the side mold body 4 are the main structures of the tooling. The lower mold body 2 and the combined upper mold body are both made of metal structures, the side mold body 4 is made of a composite material structure, and 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 mold surface has parallel closed angle surfaces for easy mold opening. The lower mold body 2 is provided with a mold opening module 9 and a mold opening groove 1 to facilitate demolding of the composite material part after curing. Two pressing molds are prepared at the special-shaped notch. The gap value between the first pressing mold 5 and the lower mold body 2 is 1 / 2 of the thickness of the part at this position, and the gap value between the second pressing mold 7 and the lower mold body 2 is consistent with the thickness of the part at this position.

[0032] During molding, the parts are layered on the lower mold body 2 according to the part layering information. During the layering process, the cloth layer is compacted at room temperature every 1-3 layers. After the lower mold body cloth layer 6 is layered, the first pressing die 5 is placed in the groove of the special-shaped notch of the lower mold body 2. A vacuum bag is pasted on the lower mold body 2, and the lower mold body cloth layer 6 is hot-compacted using an autoclave at parameters of 65±5℃, constant temperature for 30-40min, and positive pressure of 0.6Mpa, so that the cloth layer of the part laid on the lower mold body 2 in the special-shaped notch area reaches the theoretical thickness. After compaction, the tooling is cooled to room temperature, and the first pressing die 5 is taken out to continue the subsequent layering.

[0033] According to the part laying information, the cloth layer that needs to be laid on the upper mold body in the prior art is changed to be laid on the lower mold body 2. For the layers exceeding the overlapping area of ​​the upper mold body and the lower mold body 2, an isolation film is used for protection between each layer of cloth. During the laying process, the cloth layer is compacted at room temperature every 1-3 layers. After the cloth layer is laid, the second pressing mold 7 is placed in the groove of the lower mold body 2, and a vacuum bag is pasted for compaction at room temperature.

[0034] After compaction, the squeezed cloth layer at the mold opening groove 1 is cleaned, and the raw silicone sheet 1453D is used to block the glue at the mold opening groove to prevent excessive resin overflow during the curing process. After the above cloth layer cleaning and glue blocking operations are completed, the combined upper mold body and the lower mold body 2 are molded together. After the mold is closed, a vacuum bag is pasted in this state and compacted at room temperature to make the combined upper mold body fit the lower mold body.

[0035] Then, the cloth layer of the non-overlapping area of ​​the upper mold body separated by the isolation film is reversely laid to the molding area of ​​the edge of the combined upper mold body. Then, the twist strip is placed, and the cloth layer of the side mold body is continued to be laid, and the side mold body 4 is closed, and the vacuum bag is pasted and put into the autoclave for curing.

[0036] The demolding process after curing is to first separate the side mold body from the part, then separate the combined upper mold body from the part, and then separate the part from the lower mold body through the demolding module and the demolding groove.

[0037] The following examples illustrate the process of laying, compacting, curing and demolding:

[0038] Step 1: Lay the lower mold body cloth layer 6 on the lower mold body 2. After paving, use the first pressing mold 5 to place it in the groove of the special-shaped notch of the lower mold body 2 to make it reach Figure 3 State, paste vacuum bag for hot compaction parameters 65±5℃, constant temperature 30-40min, positive pressure 0.6Mpa;

[0039] Step 2: Take out the first die 5 from the groove of the lower die 2, and lay the upper die cloth layer 8 on the tooling lower die 2. When laying, use an isolation film to protect the layers of the reserved cloth layer of the upper die edge strip. Use the second die 7 to place it in the groove of the lower die 2 to achieve Figure 4 state, and paste the vacuum bag for compaction at room temperature;

[0040] Step 3: Take out the second pressing 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 use a raw silicone sheet 1453D to be placed at the mold opening groove 1 to block the glue;

[0041] Step 4: After the upper mold body 1 3-1 and the upper mold body 2 3-2 are combined, they are molded together with the lower mold body 2, and then compacted at room temperature. The cloth layer of the non-overlapping area of ​​the upper mold body cloth layer 8 protected by the isolation film is reversed and laid on the combined upper mold body, and then the twist strips are placed, the side mold layers are laid, and the side mold body 4 is closed to achieve Figure 5 state;

[0042] Step 5: The pasted vacuum bag is put into the autoclave for curing. After curing, the demolding process is to first separate the side mold body 4 from the parts, then separate the combined upper mold body 3 from the parts respectively, and then separate the parts from the lower mold body 2 through the demolding module 9 and the demolding groove 1.

Claims

1. A mold for a composite I-beam at a special-shaped notch, characterized in that: The mold comprises a lower mold body (2), a combined upper mold body, a side mold body (4), a first pressing mold (5), a second pressing mold (7) and an opening module (9), wherein the lower mold body (2) has a groove for forming a special-shaped notch, the gap value between the first pressing mold (5) and the groove is 1 / 2 of the thickness of the part at this position, and is used for vacuum hot pressing the lower mold body cloth layer (6); the gap value between the second pressing mold (7) and the groove is consistent with the thickness of the part at this position, and is used for vacuum hot pressing the combination of the formed lower mold body cloth layer (6) and the unformed upper mold body cloth layer (8); an opening groove (1) is provided at the angle of the groove, and an opening module (9) is arranged on the outer side of the upper end of the lower mold body (2); the combined 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 and the mold is formed, the side mold body (4) is installed at the outer end.

2. The mold for the composite I-beam at the irregular notch according to claim 1, characterized in that: The combined upper mold body comprises an upper mold body 1 (3-2) and an upper mold body 2 (3-2), and 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 I-beam at the irregular notch according to claim 1, characterized in that: The upper mold body 1 (3-2) and the upper mold body 2 (3-2) have a weight-reducing notch structure on the non-molding surface.

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

5. The mold for the composite 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 the outer end for supporting the side mold body (4).

6. The mold for the composite I-beam at the irregular notch according to claim 1, characterized in that: A support block for supporting the combined upper mold body is provided in the mold opening groove (1).

7. A method for forming a composite I-beam according to any one of claims 1 to 6 using a mold at a special-shaped notch, characterized in that: The method comprises the following steps: S1, laying a lower mold cloth layer (6) on the lower mold (2), placing a first pressing mold (5) in a groove of the lower mold (2) after the laying is completed, and pasting a vacuum bag for hot compaction; S2, taking out the first pressing mold (5) from the groove, laying the upper mold body cloth layer (8) on the lower mold body (2), using an isolation film to protect the layers of the reserved cloth layer of the upper mold body edge strip, placing the second pressing mold (7) in the groove of the lower mold body (2), and pasting a vacuum bag to perform room temperature compaction; S3, taking the second pressing mold (7) out of the groove, cleaning the remaining cloth layer at the mold opening groove (1), and placing a raw silicone sheet 1453D at the mold opening groove (1) to block the glue; S4, closing the combined upper mold body and the lower mold body (2), compacting them at room temperature after closing the mold, laying the cloth layer of the non-overlapping area of ​​the upper mold body cloth layer (8) protected by the isolation film on the combined upper mold body, subsequently placing the twist strip, laying the side mold layer, and closing the side mold body (4); Step 5: Put the paste-made vacuum bag into the autoclave for curing, and open the mold after curing.

8. The method for forming a composite I-beam at a mold at a special-shaped notch according to claim 7, characterized in that: Hot pressing parameters in S1: 65±5°C, constant temperature for 30-40min, positive pressure 0.6Mpa.

9. The method for forming a composite I-beam at a mold at a special-shaped notch according to claim 7, characterized in that: The demoulding process is to first separate the side mold body (4) from the part, then separate the combined upper mold body from the part, and then separate the part from the lower mold body (2) through the demoulding module (9) and the demoulding groove (1).

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