Large-curvature fairing type composite material part forming device and forming method

Abstract

The invention belongs to the technical field of aviation composite material forming machining, and discloses a large-curvature fairing type composite material workpiece forming device and method.The device comprises an upper core mold forming mold, a lower core mold forming mold, a lower core mold forming mold, a lower core mold forming mold and an upper core mold forming mold, and the molded surface of the upper core mold forming mold is designed and manufactured based on the outer molded surface of a product; the molded surface of the product forming die is designed and manufactured based on the inner molded surface of the product, and the upper core die and the product forming die are matched for use to form the product. The technical problems of surface wrinkling, fiber buckling, sinking and the like of the aerodynamic shape surface of the composite material part of the large-curvature fairing are solved. And the surface quality of the product is ensured, and the defects of wrinkles, fiber buckling, sinking and the like are reduced and eliminated.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material forming and processing in aviation manufacturing, and specifically relates to a forming device and a forming method for a composite material part of a large curvature fairing. Background Art

[0002] Composite materials have the characteristics of high specific strength, high specific modulus, good impact resistance, and high fatigue strength. They have long been the focus of the aviation and aerospace fields, especially in the aviation field. Various parts are widely used. The fairing is a smooth appearance kit, the purpose of which is to cover and protect special parts of the aircraft, such as landing gear, flying antennas, fuel pipes, etc., to avoid excessive air resistance, reduced aerodynamic performance and increased noise. In addition, the fairing can also improve the shape, beautify the overall appearance, improve flight stability and reduce energy loss, so it plays an important role in the aircraft structure. At the same time, the functional layer of the outer surface of the fairing has the function of lightning protection, so ensuring that the shape of its aerodynamic shape surface is smooth and flat is of great significance to the functionality of the part. However, the fairing is often a large curvature part. In order to avoid product deformation and ensure the part profile, its tooling often uses a punch design, so the surface quality of its aerodynamic shape surface is often not guaranteed. During on-site production, due to frequent quality problems such as wrinkles, fiber buckling, and dents on the product surface, the product scrap rate is high, and qualified products often need to be repeatedly repaired to ensure surface quality, delaying production progress and affecting the functionality of parts.

[0003] In summary, there is an urgent need for a forming device and a forming method for a large curvature fairing, which is low-cost, simple and reliable, and can reduce and eliminate defects such as wrinkles, fiber buckling, and depressions on the aerodynamic shape surface of the fairing composite material product to ensure surface quality. Summary of the invention

[0004] The present invention discloses a large curvature fairing composite material part forming device and forming method, which can avoid the problems of aerodynamic shape surface wrinkles, fiber buckling, depression and the like of large curvature fairing composite material parts, and ensure the surface quality of the product.

[0005] In order to achieve the above invention objectives, the technical solutions adopted in this application are as follows:

[0006] A large curvature fairing composite material forming device, comprising:

[0007] The upper core mold forming mold, whose surface is designed and manufactured based on the product outer surface, is used for forming the upper core mold of non-metallic materials;

[0008] The product forming mold has a molding surface designed and manufactured based on the inner molding surface of the product, and the upper core mold is used in conjunction with the product forming mold to form the product.

[0009] As a further solution of the present invention: the upper core mold forming mold is made of metal material, which includes an upper core mold forming mold tooling body and an upper core mold forming mold core mold, and the upper core mold forming mold core mold stands on the upper core mold forming mold tooling body.

[0010] As a further solution of the present invention: an upper core mold forming mold air guide groove is designed on the upper core mold forming mold tooling body, and the upper core mold forming mold air guide groove is arranged around the upper core mold forming mold core mold, and the upper core mold forming mold core mold is provided with an upper core mold forming mold engraving line and an upper core mold forming mold hole position cross engraving line.

[0011] As a further solution of the present invention: the upper core mold is made of rubber sheets and carbon fiber fabrics, and its inner surface is matched with the outer surface of the product.

[0012] As a further solution of the present invention: the design basis of the upper core mold is the required stiffness, which is achieved by adjusting the number of layers of carbon fiber fabric. The high stiffness design of three layers of rubber sheets + two layers of carbon fiber fabric can be adopted for the plane areas on both sides of the corresponding product, the medium stiffness design of three layers of rubber sheets + one layer of carbon fiber fabric can be adopted for the R corner area, and the low stiffness design of three layers of rubber sheets can be adopted for the area between the two R corners.

[0013] As a further solution of the present invention: the upper core mold is formed by paving, the three layers of rubber sheets are all paved as whole layers, and the paving order is P1, P3, and P5. The two layers of carbon fiber fabrics are all paved as reinforcement layers, and the paving order is P2 and P4.

[0014] As a further solution of the present invention: the product molding mold is made of metal material, which includes a tooling body and a lower core mold. The lower core mold stands on the tooling body. The lower core mold is a male mold, and its molding surface is designed and manufactured based on the inner molding surface of the product.

[0015] As a further solution of the present invention: an air guide groove and a plurality of target heads are designed on the tooling body, the air guide groove is arranged around the lower core mold, a net dimension line and an allowance line are provided on the lower core mold, a connecting hole is made in the area between the net dimension line and the allowance line, and is equipped with positioning pins of corresponding sizes.

[0016] As a further solution of the present invention: the position of the cross mark on the hole position of the upper core mold forming mold is matched with the position of the connecting hole.

[0017] A method for forming a composite material part of a large curvature fairing, using the above-mentioned part forming device, comprises the following steps:

[0018] Step 1: Apply a release agent on the upper core mold forming mold, and cut the carbon fiber fabric prepreg and rubber sheet required for the upper core mold forming;

[0019] Step 2: Lay the rubber sheets on the upper core mold. During the paving process, the rubber sheets and the carbon fiber fabric prepreg are only allowed to be butted. The carbon fiber fabric prepreg and rubber sheets should be laid beyond the engraved lines of the upper core mold. Place sealing tape on the outside of the air guide groove of the upper core mold. At the same time, vacuum compaction is required when laying the rubber sheets P1, P3, and P5 layers.

[0020] Step 3: Bag making and sending to autoclave for curing;

[0021] Step 4: Remove the vacuum bag, demould the upper core mold, cut according to the marking lines of the upper core mold, and drill holes according to the cross marking lines of the hole positions of the upper core mold. The hole diameter should be consistent with the size of the connecting hole.

[0022] Step 5: Apply mold release agent to the inside of the upper core mold and the lower core mold;

[0023] Step 6: Lay the prepreg on the lower core mold. Before paving to the product functional layer, the overlapping method during the paving process is to overlap the geometric upper side on the geometric lower side;

[0024] Step 7: Lay the porous isolation film, assemble the upper core mold according to the connection holes and positioning pins, and then make the bag. The sealing tape used for bag making is placed outside the air guide groove;

[0025] Step 8: Send to autoclave for pre-compaction;

[0026] Step 9: Remove the vacuum bag, isolation film, and upper core mold;

[0027] Step 10: Use laser projection equipment to project the contour of the functional layer with the target head as the reference, and lay the functional layer according to the contour of the functional layer. It is required that the functional layer above the geometry overlaps the functional layer below the geometry during laying, lay the porous isolation film, and then assemble the upper core mold according to the connection holes and positioning pins, and vacuum compact for at least 15 minutes;

[0028] Step 11: Bag making and sending to autoclave for curing;

[0029] Step 12: Remove the vacuum bag, isolation film, and upper core mold to demould the product.

[0030] Compared with the prior art, the beneficial effects of this application are:

[0031] 1. Low manufacturing cost and simple structure.

[0032] 2. According to the surface characteristics of the parts, the upper core mold is specially designed. In the position where the pressure transmission effect is not good during the curing process of the product, the rigidity of the upper core mold is reduced by not laying or laying less carbon fiber prepreg at the corresponding position of the upper core mold, thereby utilizing the thermal expansion of the rubber sheet of the upper core mold during the curing process to improve the fit of the upper core mold to the parts and make the pressure transmission of the parts uniform during the curing process. The surface quality of the product is guaranteed, and defects such as wrinkles, fiber buckling, and depressions are reduced and eliminated.

[0033] 3. Pre-compaction and long-term vacuum compaction reduce the air between product layers during the molding process, so that less air is mixed into the prepreg, ensuring the low porosity and lossless indicators of the product.

[0034] 4. By clarifying the overlap method of the prepreg and the lightning protection surface film sheet, the possibility of copper mesh wrinkling is reduced and the functionality of the parts is ensured.

[0035] The present application is further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0037] In the attached picture:

[0038] Figure 1 This is a schematic diagram of the molding die for the product of this application;

[0039] Figure 2 This is a schematic diagram of the core mold forming mold in this application;

[0040] Figure 3 This is a schematic diagram of the core mold paving for this application.

[0041] Explanation of the reference numerals in the figure: 1-upper core mold, 2-tooling body, 3-air guide groove, 4-target head, 5-locating pin, 6-connecting hole, 7-lower core mold, 8-net dimension line, 9-allowance line, 10-upper core mold forming mold hole position cross mark, 11-upper core mold forming mold core mold, 12-upper core mold forming mold mark line, 13-upper core mold forming mold air guide groove, 14-upper core mold forming mold tooling body, 15-upper core mold area without carbon cloth, 16-upper core mold area with one layer of carbon cloth, 17-upper core mold area with two layers of carbon cloth. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0043] The present invention takes the aircraft tail wing tip fairing as an example, a molding device for a large curvature fairing composite material product, which is composed of two sets of tooling, a product molding die and an upper core mold molding die. Both the product molding die and the upper core mold molding die are made of metal. When manufacturing the product, the product molding die is used in conjunction with an upper core mold of a non-metallic material formed by the upper core mold molding die.

[0044] Figure 1 The figure shows the matching use status of the product forming mold, including the tooling body 2, the lower core mold 7, the upper core mold 1, the target head 4, the air guide groove 3, the connecting hole 6, the positioning pin 5, the net dimension line 8, and the allowance line 9. The upper core mold 1 is formed by non-metal, and its inner profile is designed based on the outer profile of the part. It is made of rubber sheet and carbon fiber fabric and needs to be formed on the upper core mold forming mold. All other parts are made of metal. The lower core mold 7 is a punch. The profile is designed and manufactured based on the inner profile of the product. It is marked with a net dimension line 8 and an allowance line 9, and a connecting hole 6 is made in the area between the net dimension line 8 and the allowance line 9, and is equipped with a positioning pin 5 of corresponding size. The tooling body 2 is a flat structure, and the tooling body is provided with an air guide groove 3 and a target head 4.

[0045] Figure 2 The upper core mold forming mold is shown, which includes an upper core mold forming mold tooling body 14, an upper core mold forming mold core mold 11, an upper core mold forming mold score line 12, an upper core mold forming mold air guide groove 13, and an upper core mold forming mold hole position cross score line 10. The design and manufacture of the upper core mold forming mold 11 should be based on the product appearance. The upper core mold forming mold tooling body 14 is designed with an upper core mold forming mold air guide groove 13, and the upper core mold forming mold score line 12 is located on the upper core mold forming mold core mold 11. The upper core mold forming mold hole position cross score line 10 is located on the upper core mold forming mold core mold 11, and the drilled hole position corresponds to the connecting hole 6.

[0046] Figure 3The upper core mold paving process is shown. The design basis of the upper core mold 1 is the required stiffness, which is achieved by adjusting the number of layers of carbon fiber fabric. The upper core mold is paved with three layers of rubber sheets on the P1, P3, and P5 layers, all of which are whole layers, and the carbon fiber fabric prepreg is paved on the P2 and P4 layers as a reinforcement layer. Among them, the area with three layers of rubber sheets + two layers of carbon fiber fabric has the highest stiffness, and the three layers of rubber sheets have the lowest stiffness. The design principle is: the high stiffness design of three layers of rubber sheets + two layers of carbon fiber fabric can be adopted for the plane area 17 on both sides of the corresponding product, the medium stiffness design of three layers of rubber sheets + one layer of carbon fiber fabric can be adopted for the R angle area 16, and the low stiffness design of three layers of rubber sheets can be adopted for the area 15 between the two R angles.

[0047] The molding method of the present invention is as follows:

[0048] 1) Apply a release agent on the upper core mold 11, and manually cut the carbon fiber fabric prepreg and rubber sheet required for the upper core mold molding.

[0049] 2) Lay the rubber sheet on the upper core mold 11. During the paving process, the rubber sheet and the carbon fiber fabric prepreg are only allowed to be butted. The carbon fiber fabric prepreg and the rubber sheet should be laid beyond the upper core mold 12. Place sealing tape on the outside of the air guide groove 13 of the upper core mold, and vacuum compaction is required when laying the rubber sheets P1, P3, and P5 layers.

[0050] 3) Make bags and send to autoclave for curing.

[0051] 4) Remove the vacuum bag and demould the upper core mold 1. Cut according to the upper core mold molding mold score line 12, and drill according to the upper core mold molding mold hole position cross score line 10, the hole diameter is consistent with the connection hole 6.

[0052] 5) Apply mold release agent to the inside of the upper core mold 1 and the lower core mold 7 of the product.

[0053] 6) Lay the prepreg on the lower core mold 7 until it reaches the product functional layer. During the paving process, the overlapping area is laid in a manner that the geometric upper part overlaps the geometric lower part.

[0054] 7) Lay the porous isolation film, assemble the upper core mold 1 according to the connecting holes 6 and the positioning pins 5, and then make the bag. The sealing tape used for bag making is placed outside the air guide groove 3.

[0055] 8) Send to autoclave for pre-compaction.

[0056] 9) Remove the vacuum bag, isolation film and upper core mold 1.

[0057] 10) Use laser projection equipment to project the contour of the functional layer with the target head 4 as the reference, and lay the functional layer according to the contour of the functional layer. It is required that the functional layer above the geometry overlaps the functional layer below the geometry during laying. Then lay the porous isolation film, and then assemble the upper core mold 1 according to the connection hole 6 and the positioning pin 5, and vacuum compact for at least 15 minutes. The overlapping method of the prepreg and the lightning protection surface film sheet is clarified, which reduces the possibility of wrinkling of the copper mesh and ensures the functionality of the parts.

[0058] 11) The product prefabricated with the functional layer is bagged and sent to the autoclave for curing. Then the vacuum bag, isolation film, and upper core mold are removed to demould the product.

[0059] The upper core mold is specially designed according to the surface characteristics of the product. In the process of product curing, the rigidity of the upper core mold is reduced by not laying or laying less carbon fiber prepreg at the corresponding position of the upper core mold at the position where the pressure transmission effect is poor. In this way, the thermal expansion of the rubber sheet of the upper core mold during the curing process is utilized to improve the fit of the upper core mold to the part, so that the pressure transmission of the product during the curing process is uniform. The surface quality of the product is guaranteed, and defects such as wrinkles, fiber buckling, and depressions are reduced and eliminated. At this point, the purpose of the present invention is achieved.

[0060] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A large curvature fairing composite material forming device, characterized in that: include: The upper core mold forming mold, whose surface is designed and manufactured based on the product outer surface, is used for forming the upper core mold of non-metallic materials; The product forming mold has a molding surface designed and manufactured based on the inner molding surface of the product, and the upper core mold is used in conjunction with the product forming mold to form the product.

2. The large curvature fairing composite material forming device according to claim 1 is characterized in that: The upper core mold forming mold is made of metal material, and comprises an upper core mold forming mold tooling body and an upper core mold forming mold core mold, and the upper core mold forming mold core mold stands on the upper core mold forming mold tooling body.

3. The large curvature fairing composite material forming device according to claim 2, characterized in that: An upper core mold forming mold air guide groove is designed on the upper core mold forming mold tooling body, and the upper core mold forming mold air guide groove is arranged around the upper core mold forming mold core mold, and the upper core mold forming mold core mold is provided with an upper core mold forming mold engraving line and an upper core mold forming mold hole position cross engraving line.

4. A large curvature fairing composite material forming device according to claim 2 or 3, characterized in that: The upper core mold is made of rubber sheets and carbon fiber fabrics, and its inner surface is matched with the outer surface of the product.

5. The device for forming composite parts of large curvature fairing according to claim 4, characterized in that: The design basis of the upper core mold is the required stiffness, which is achieved by adjusting the number of layers of carbon fiber fabric. For the flat areas on both sides of the corresponding product, a high stiffness design of three layers of rubber sheets + two layers of carbon fiber fabric can be adopted, for the R corner area, a medium stiffness design of three layers of rubber sheets + one layer of carbon fiber fabric can be adopted, and for the area between the two R corners, a low stiffness design of three layers of rubber sheets can be adopted.

6. The large curvature fairing composite material forming device according to claim 5, characterized in that: The upper core mold is formed by paving, and the three layers of rubber sheets are all paved in whole layers, and the paving order is P1, P3, and P5. The two layers of carbon fiber fabrics are all paved in reinforcement layers, and the paving order is P2 and P4.

7. A large curvature fairing composite material forming device according to claim 5 or 6, characterized in that: The product forming mold is made of metal material, and comprises a tooling body and a lower core mold. The lower core mold stands on the tooling body. The lower core mold is a male mold, and its molding surface is designed and manufactured based on the inner molding surface of the product.

8. The large curvature fairing composite material forming device according to claim 7, characterized in that: The tooling body is designed with an air guide groove and a plurality of target heads. The air guide groove is arranged around the lower core mold. The lower core mold is provided with a net size line and an allowance line. A connecting hole is made in the area between the net size line and the allowance line, and is also equipped with positioning pins of corresponding sizes.

9. The large curvature fairing composite material forming device according to claim 8, characterized in that: The position of the cross-mark of the hole position of the upper core mold forming mold is matched with the position of the connecting hole.

10. A method for forming a composite material part of a large curvature fairing, using the part forming device according to claim 7, characterized in that: The steps include: Step 1: Apply a mold release agent on the upper core mold forming mold, and cut the carbon fiber fabric prepreg and rubber sheet required for the upper core mold forming; Step 2: Lay the rubber sheets on the upper core mold. During the paving process, the rubber sheets and the carbon fiber fabric prepreg are only allowed to be butted. The carbon fiber fabric prepreg and rubber sheets should be laid beyond the engraved lines of the upper core mold. Place sealing tape on the outside of the air guide groove of the upper core mold. At the same time, vacuum compaction is required when laying the rubber sheets P1, P3, and P5 layers. Step 3: Bag making and sending to autoclave for curing; Step 4: Remove the vacuum bag, demould the upper core mold, cut according to the marking lines of the upper core mold, and drill holes according to the cross marking lines of the hole positions of the upper core mold. The hole diameter should be consistent with the size of the connecting hole. Step 5: Apply mold release agent to the inside of the upper core mold and the lower core mold; Step 6: Lay the prepreg on the lower core mold. Before paving to the product functional layer, the overlapping method during the paving process is to overlap the geometric upper side on the geometric lower side; Step 7: Lay the porous isolation film, assemble the upper core mold according to the connection holes and positioning pins, and then make the bag. The sealing tape used for bag making is placed outside the air guide groove; Step 8: Send to autoclave for pre-compaction; Step 9: Remove the vacuum bag, isolation film, and upper core mold; Step 10: Use laser projection equipment to project the contour of the functional layer with the target head as the reference, and lay the functional layer according to the contour of the functional layer. It is required that the functional layer above the geometry overlaps the functional layer below the geometry during laying, lay the porous isolation film, and then assemble the upper core mold according to the connection holes and positioning pins, and vacuum compact for at least 15 minutes; Step 11: Bag making and sending to autoclave for curing; Step 12: Remove the vacuum bag, isolation film, and upper core mold to demould the product.

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