Co-curing forming mold and method for stepped composite material part

Abstract

The invention provides a step type composite material part co-curing forming mold and method. The step type composite material part comprises a skin layer and a step layer. The mold comprises a forming mold frame, a forming molded surface, a thickness control strip, a backup plate and a target positioning hole, the forming molded surface is arranged above the forming die frame, is in a step shape and is matched with the molded surface of the step type composite material part; when the step layer is paved, a target head of a laser projector is arranged in the target positioning hole, a thickness control strip is arranged on the vertical surface of the step, a backup plate is arranged at the position, close to the vertical surface of the step, of the higher step of the molding surface, and when the thickness of the step layer subjected to hot pressing is flush with that of the higher step of the molding surface, the thickness control strip and the backup plate are removed, and the skin layer can be paved. The device is used for realizing no lap joint step after the plane separation surface is butted, and the whole device is in a smooth transition aerodynamic shape.

Description

Technical Field

[0001] The present invention relates to the field of composite part manufacturing, and specifically to a co-curing forming die and method for stepped composite parts. Background Art

[0002] With the application of composite parts in aircraft expanding from secondary load-bearing structures to primary load-bearing structures, the outer wing panels and central wing panels of aircraft composites are the best embodiments of the application of primary load-bearing structures. The butt joint of the root of the outer wing panel and the central wing panel is generally achieved by a process separation surface design.

[0003] In traditional separation surface designs, for example, the T-shaped stiffened panel of the A350 aircraft transfers loads through a "丄"-shaped structure and a butt joint strap structure. While the I-shaped stiffened panel of the B787 aircraft transfers loads through a "土"-shaped structure and a stringer butt joint structure.

[0004] Whether it is a "丄"-shaped structure or a "土"-shaped structure, a small butt joint step will be generated at the butt joint outer profile surface of the wing panel and the central wing panel, affecting the smooth aerodynamic profile of the aircraft. Summary of the Invention

[0005] The present invention provides a co-curing forming die and method for stepped composite parts, which is used to achieve a smooth aerodynamic profile without overlapping steps after the butt joint of the aircraft separation surface.

[0006] The first aspect of the present invention provides a co-curing forming die for stepped composite parts. The stepped composite parts include: a skin layer and a stepped layer; the die includes: a forming die frame, a forming profile, a thickness control strip, a backing plate, and a target positioning hole;

[0007] The forming profile is arranged above the forming die frame, and the forming profile is stepped and matches the profile of the stepped composite part;

[0008] When laying the stepped layer, a target head of a laser projector is arranged in the target positioning hole, a thickness control strip is arranged on the stepped vertical surface, and a backing plate is arranged on the higher-level step of the forming profile near the stepped vertical surface. When the thickness of the stepped layer after hot compaction is flush with the higher-level step of the forming profile, the thickness control strip and the backing plate are removed, and then the skin layer can be laid.

[0009] Optionally, it further includes: a uniform pressing plate, a uniform pressing plate forming die, a uniform pressing plate positioning hole, and a positioning pin;

[0010] The profile of the uniform pressing plate forming die is consistent with the profile of the stepped layer, and is used to generate a uniform pressing plate, and the profile of the uniform pressing plate matches the profile of the stepped layer;

[0011] Both ends of the equalizing plate and both ends of the lower step of the forming surface are provided with equalizing plate positioning holes. When the step layer is hot pressed, the equalizing plate is fixed to the lower step of the forming surface by positioning pins.

[0012] Optionally, it also includes: a pad plate;

[0013] Pad plates are arranged at both ends of the lower steps of the forming profile, and the pad plates are wedge-shaped;

[0014] The sum of the width of the pads at both ends and the width of the step layer is the same as the width of the lower step of the forming surface;

[0015] The length of the pad plate shall not be less than the length of the step layer.

[0016] Optionally, the thickness control strip is formed by stacking multiple layers of soft material that can be bonded to the mold and can contact the prepreg, and the thickness of the thickness control strip is within the range of 0.5 mm to 0.8 mm.

[0017] Optionally, the thickness of the pressure equalizing plate is within a range of 2 mm to 2.5 mm.

[0018] Optionally, the backing plate is made of aluminum material, and the thickness of the backing plate is 10% of the sum of the thickness of the pressure plate and the maximum thickness of the step layer.

[0019] A second aspect of the present invention provides a step-type composite material part co-curing molding method, using the step-type composite material part co-curing molding mold as described in any one of the first aspects, the molding method comprises the following steps:

[0020] S1. Before paving, a thickness-control strip with a certain thickness is formed by bonding multiple layers of soft materials on the step facade of the molding surface, and a support plate is placed and positioned on the step of the molding surface;

[0021] S2. Place the target head on the target positioning hole to form a paving laser projection line, and pave the prepreg on the lower step of the molding surface according to the projection line, and perform cold drawing and compaction once for every 3 layers of paving, and perform pre-compaction once for every preset paving thickness;

[0022] S3. After the prepreg material of the step layer is laid, the thickness control strip bonded to the step facade of the step forming mold is removed;

[0023] S4. Place and fix a uniform pressure plate on the step layer where the prepreg is laid;

[0024] S5. Complete the bagging and packaging of the step layer, and enter the autoclave to perform hot compaction of the step layer prepreg, with the hot compaction temperature controlled within 80°C to 90°C;

[0025] S6. After the hot compaction is completed, the equalizing plate and the support plate are removed, and the flushness between the prepreg blank and the higher step of the molding surface is detected; if flush, enter S7; if higher than the higher step, execute S5 again; if lower than the higher step, compensate the prepreg according to the amount lower than the higher step, and execute S5 again;

[0026] S7. Lay out the skin layer prepreg to form the composite parts.

[0027] Optionally, the preset thickness is 5 mm to 6 mm.

[0028] The present invention provides a co-curing molding mold and method for stepped composite material parts, which have the following advantages: 1) the molding mold has a simple structure, the material is easily available, and the processability is strong; 2) the investment cost is low, and single-step or multi-step composite material parts can be co-cured in one piece; 3) the technical risk is low, and the internal quality that meets the document requirements can be achieved by controlling key parameters and technologies; 4) the stepped exterior surface wall panel manufactured by this method can achieve an aerodynamic shape with no overlapping steps after the aircraft separation surfaces are butted and a smooth transition as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of a forming die for a stepped profile;

[0030] Figure 2 It is a side view of the forming die of the stepped profile;

[0031] Figure 3 It is a schematic diagram of a uniform pressure plate forming die;

[0032] Figure 4 It is a schematic diagram of the butt joint of the separated surfaces of the wall panels that can be realized by the present invention;

[0033] Description of reference numerals:

[0034] 1-forming mold frame, 2-forming surface, 3-pad plate, 4-thickness control strip, 5-equalizing plate, 7-support plate, 8-target positioning hole, 9-equalizing plate positioning hole, 11-step surface, 12-jointing strip plate, 13-wall panel skin, 14-beam. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. It is obvious that 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 belong to the scope of the present invention.

[0036] like Figure 1-4As shown, the present invention provides a step-type composite material part co-curing molding die, including: a molding die frame, a molding surface, a pad plate, a thickness control strip, a uniform pressure plate, a uniform pressure plate molding die, a backing plate, a target positioning hole, a uniform pressure plate positioning hole, a positioning pin, and a step surface.

[0037] The forming surface is generally a metal mold, which is located on the forming mold frame. Pad plates, target positioning holes, and equalizing plate positioning holes are set in the margin area of ​​the forming surface. After the step area is paved, the pad plate is used to eliminate the step in the mold margin area, which is convenient for the subsequent automatic placement of parts. The thickness control strip, equalizing plate, and support plate are used to realize the step surface forming. The target positioning hole and the equalizing plate positioning hole are used for positioning during the paving process and the equalizing plate placement positioning respectively.

[0038] The thickness control strip is made of multiple layers of soft materials that can be bonded to the mold and in contact with the prepreg. The thickness control strip is bonded to the step facade of the step forming mold before the prepreg is laid on the step profile, ensuring that there is a gap of 0.5mm to 0.8mm between the prepreg layer and the mold. This prevents the prepreg from forming wrinkles on the step facade. The thickness control strip is removed after the step profile is laid.

[0039] The pressure plate forming mold is generally a metal mold, which is used to form a pressure plate covering the completed step surface. The surface of the pressure plate forming mold is consistent with the inner surface of the step. A composite laminate is formed by laying a certain thickness of prepreg on the pressure plate forming mold and curing it in an autoclave. The thickness of the pressure plate is controlled at 2mm to 2.5mm and is not easy to be too thick. It is positioned and connected to the forming surface through the positioning holes and positioning pins of the pressure plate to ensure that the overall prepreg is flat, dense, and wrinkle-free during the heating and pre-compacting process of the step area, which is convenient for subsequent paving. If the step surface is a plane, the pressure plate is replaced by a steel plate, and the pressure plate forming mold is no longer needed.

[0040] The backing plate is placed on the step and flush with the edge of the step to assist in the forming of the step profile and prevent the preform that is higher than the step from collapsing and forming wrinkles during the compaction process. The backing plate is generally made of aluminum because it is not solidified with the parts in the tank. The thickness of the backing plate is made according to 10% of the sum of the thickness of the uniform pressure plate and the maximum thickness at the step.

[0041] The present invention also provides a step-type composite material part co-curing molding method, comprising the following steps:

[0042] 1. Before paving, a thickness-control strip with a certain thickness is formed by bonding multiple layers of soft materials on the step facade of the molding surface, and a support plate is placed and positioned on the step of the molding surface;

[0043] 2. Place the target head on the target positioning hole to form a paving laser projection line, and pave the prepreg on the molding surface according to the projection line. Perform cold oil compaction every 3 layers to ensure the density between the layers.

[0044] 3. According to the height of the steps, the number of pre-compacting times during the paving process is selected. Generally, pre-compacting is performed every 5mm to 6mm of paving to ensure that the prepreg layers are dense and close to the curing state to the greatest extent;

[0045] 4. According to the actual cured thickness of the prepreg, the theoretical number of paving layers needs to be increased or decreased during the paving process. For prepregs whose thickness after curing is closer to the theoretical upper limit, reduce the number of prepreg layers according to the value of the thickness deviation, and increase the number of layers if the thickness is lower. The above operations can avoid the situation where the prepreg and the molding surface at the step cause fiber wrinkles inside the part;

[0046] 5. After the prepreg material of the step profile is laid, remove the thickness control strip bonded to the step facade of the step forming mold;

[0047] 6. On the step profile where the prepreg is laid, place the composite material equalizing plate or steel equalizing plate that has been pre-cured and formed using the equalizing plate forming mold, and position and connect the composite material equalizing plate or steel equalizing plate through the equalizing plate positioning holes and positioning pins in the step profile margin area.

[0048] 7. After the bagging and packaging of the formed surface is completed, the prepreg of the step surface is put into the autoclave for hot compaction. The hot compaction temperature is controlled at 80℃~90℃.

[0049] 8. After hot compaction, remove the equalizing plate and the backing plate, and check the level between the prepreg blank and the molding surface. If it is higher than the molding surface, perform hot compaction again according to step 7. If it is lower than the molding surface, compensate the prepreg according to the amount lower than the molding surface until it is flush with the molding surface.

[0050] 9. Placing a pad plate in the excess area of ​​the molding surface can realize the automatic placement of subsequent prepreg until the paving is completed. The subsequent processes can be carried out according to the general processes of composite parts molding.

[0051] Exemplarily, in a specific embodiment, the step-type composite material part co-curing molding mold provided by the present invention includes: a molding mold frame 1, a molding surface 2, a pad plate 3, a thickness control strip 4, a uniform pressure plate 5, a uniform pressure plate molding mold, a support plate 7, a target positioning hole 8, a uniform pressure plate positioning hole 9, a positioning pin, and a step surface 11.

[0052] The forming surface 2 is generally a metal mold, which is located on the forming mold frame 1. The pad plate 3, the target positioning hole 8, and the equalizing plate positioning hole 9 are set in the margin area of ​​the forming surface 2. After the step area is paved, the pad plate 3 is used to eliminate the step in the mold margin area, which is convenient for the subsequent automatic placement of parts. The thickness control strip 4, the equalizing plate 5, and the support plate 7 are used to realize the molding of the step surface 11. The target positioning hole 8 and the equalizing plate positioning hole 9 are used for positioning during the paving process and the placement of the equalizing plate 5, respectively.

[0053] The thickness control strip 4 is formed by stacking 6 layers of demoulding cloth. The thickness control strip 4 is bonded to the step facade of the step forming mold 2 before the prepreg is laid on the step profile 11 to prevent the prepreg from forming wrinkles at the step facade.

[0054] The grading plate forming mold is a metal mold used to form the grading plate 5 covering the completed step profile 11. The profile of the grading plate forming mold is consistent with the inner profile of the step. The prepreg with a thickness of 2.5 mm after paving and curing is completed by hot autoclave curing and molding to complete the manufacture of the grading plate 5.

[0055] The backing plate 7 is made of aluminum material with a thickness of 2 mm. It is placed on the step and flush with the edge of the step to assist in the forming of the step profile 11 and prevent the preform that is higher than the step from collapsing and forming wrinkles during the compaction process.

[0056] The co-curing molding method of the stepped composite material siding is as follows:

[0057] 1. Before paving, a thickness control strip 4 is formed by bonding 6 layers of release cloth on the step elevation of the step profile 11, and a support plate 7 is placed and positioned on the step of the step profile 11;

[0058] 2. Place the target head on the target positioning hole 8 to form a paving laser projection line, and pave the prepreg on the molding surface 2 according to the projection line, and perform cold drawing and compaction every 3 layers to ensure the density between the layers;

[0059] 3. Pre-compact every 5mm to 6mm to ensure that the prepreg layers are dense and close to the cured state to the greatest extent;

[0060] 4. According to the actual cured thickness of the prepreg, the theoretical number of paving layers needs to be increased or decreased during the paving process. Since the thickness of the prepreg used in this embodiment is poor after curing, 3 layers of prepreg are reduced during the prepreg paving process. The above operation avoids the situation where the step difference between the prepreg and the molding surface at the step causes fiber wrinkles inside the part;

[0061] 5. After the prepreg is laid on the step profile 11, the thickness control strip 4 bonded to the step vertical surface of the step forming mold 2 is removed;

[0062] 6. Place the equalizing plate 5 pre-cured and formed by the equalizing plate forming mold on the step profile 11 where the prepreg is laid, and position and connect the equalizing plate 5 through the equalizing plate positioning holes 9 and positioning pins in the step profile margin area.

[0063] 7. After the bagging and packaging of the formed profile 2 is completed, the prepreg of the step profile 11 is put into the autoclave for hot compaction, and the hot compaction temperature is controlled at 80°C to 90°C.

[0064] 8. After the hot compaction is completed, remove the equalizing plate 5 and the support plate 7, and check the level of the prepreg blank and the higher step of the molding surface 2. If it is level, proceed to the subsequent process; if it is higher, perform hot compaction again according to step 7. If it is lower, compensate the prepreg according to the lower amount until it is level.

[0065] 9. Place a pad plate 3 in the excess area of ​​the forming surface 2 and automatically lay the wire for the wall panel skin until the skin is laid.

[0066] 10. Assemble the long stringer skin and make bags for packaging. After completion, put them into the autoclave for curing and forming.

[0067] The finished panel skin 13 and beam 14 are assembled and connected by the butt strap 12 to form a Figure 4 The component structure shown can achieve an aerodynamic shape with no overlapping steps and smooth transition overall after the aircraft separation surfaces are butted together.

Claims

1. A step-type composite material part co-curing molding mold, characterized in that: The stepped composite material part includes: a skin layer and a stepped layer; the mold includes: a forming mold frame, a forming surface, a thickness control strip, a backing plate, and a target positioning hole; The forming profile is arranged above the forming die frame, and the forming profile is stepped and matches the profile of the stepped composite material part; When paving the step layer, a target head of a laser projector is arranged in the target positioning hole, a thickness control strip is arranged on the step facade, and a backing plate is arranged on the higher step of the forming surface near the step facade. When the thickness of the step layer after hot compaction is flush with the higher step of the forming surface, the thickness control strip and the backing plate are removed and the skin layer can be paved.

2. The step-type composite material part co-curing molding mold according to claim 1, characterized in that: Also includes: Even pressure plate, even pressure plate forming die, even pressure plate positioning hole, positioning pin; The profile of the uniform pressure plate forming die is consistent with the profile of the step layer, and is used to generate the uniform pressure plate, and the profile of the uniform pressure plate matches the profile of the step layer; Both ends of the equalizing plate and both ends of the lower step of the forming surface are provided with equalizing plate positioning holes. When the step layer is hot pressed, the equalizing plate is fixed to the lower step of the forming surface by positioning pins.

3. The step-type composite material part co-curing molding mold according to claim 1, characterized in that: Also includes: Pad plate; Pad plates are arranged at both ends of the lower steps of the forming profile, and the pad plates are wedge-shaped; The sum of the width of the pads at both ends and the width of the step layer is the same as the width of the lower step of the forming surface; The length of the pad plate shall not be less than the length of the step layer.

4. The step-type composite material part co-curing molding mold according to claim 1, characterized in that: The thickness control strip is formed by stacking multiple layers of soft materials that can be bonded to the mold and can contact the prepreg, and the thickness of the thickness control strip is within the range of 0.5mm to 0.8mm.

5. The step-type composite material part co-curing molding die according to claim 2, characterized in that: The thickness of the pressure equalizing plate is within the range of 2 mm to 2.5 mm.

6. The step-type composite material part co-curing molding mold according to claim 1, characterized in that: The backing plate is made of aluminum, and the thickness of the backing plate is 10% of the sum of the thickness of the pressure plate and the maximum thickness of the step layer.

7. A method for co-curing and molding a stepped composite material part, characterized in that: Using the step-type composite material part co-curing molding die according to any one of claims 1 to 6, the molding method comprises the following steps: S1. Before paving, a thickness-control strip with a certain thickness is formed by bonding multiple layers of soft materials on the step facade of the molding surface, and a support plate is placed and positioned on the step of the molding surface; S2. Place the target head on the target positioning hole to form a paving laser projection line, and pave the prepreg on the lower step of the molding surface according to the projection line, and perform cold drawing and compaction once for every 3 layers of paving, and perform pre-compaction once for every preset paving thickness; S3. After the prepreg material of the step layer is laid, the thickness control strip bonded to the step facade of the step forming mold is removed; S4. Place and fix a uniform pressure plate on the step layer where the prepreg is laid; S5. Complete the bagging and packaging of the step layer, and enter the autoclave to perform hot compaction of the step layer prepreg, with the hot compaction temperature controlled within 80°C to 90°C; S6. After the hot compaction is completed, the equalizing plate and the support plate are removed, and the flushness between the prepreg blank and the higher step of the molding surface is detected; if flush, enter S7; if higher than the higher step, execute S5 again; if lower than the higher step, compensate the prepreg according to the amount lower than the higher step, and execute S5 again; S7. Lay out the skin layer prepreg to form the composite parts.

8. The step-type composite material part co-curing molding method according to claim 7, characterized in that: The preset thickness is 5mm to 6mm.

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