CN115071163B - Integral co-curing forming process for S-shaped air inlet channel of multi-bulkhead carbon fiber composite material - Google Patents

Abstract

An integral co-curing molding process for an S-shaped air inlet channel of a multi-bulkhead carbon fiber composite material belongs to the technical field of composite material molding. The integral co-curing molding of the plurality of the partition frames and the air inlet channel can be completed only by one curing process, and meanwhile, the continuous layering of the plurality of the partition frames can be realized. The method can be used for co-curing and cementing co-curing of a J-shaped frame, a T-shaped frame, frames with different heights and barrel section structures. Greatly improves the structural performance and the advancement. The connection work in the later period is not needed, various problems and risks in connection of the bulkhead and the air inlet channel are avoided, and the assembly period and the cost are reduced.

Description

Integral co-curing forming process for S-shaped air inlet channel of multi-bulkhead carbon fiber composite material

Technical Field

The invention relates to an integral co-curing molding process for an S-shaped air inlet channel of a multi-bulkhead carbon fiber composite material, and belongs to the technical field of composite material molding.

Background

With the rapid development of the age, composite materials have become one of the research hotspots in the field of novel materials. Compared with the traditional material, the composite material has higher specific strength and specific modulus and good anti-fatigue, anti-corrosion and high temperature resistance, so that the composite material is widely applied in the aerospace field. Engines are the core components of an aircraft, whose performance has a direct impact on the flight envelope and efficiency of the aircraft, while air inlets, which are important aerodynamic components located most upstream of the overall propulsion system, have an important impact on the efficiency and operational capacity of the overall aircraft, as well as on their aerodynamic performance and structural strength. The modern military fighter adopts the composite material to manufacture the air inlet channel, the obtained structure can increase the flexibility of the component design, fully utilize the material anisotropy characteristic of the composite material, provide higher mechanical property for the structure, and simultaneously achieve the purpose of weight reduction.

The carbon fiber composite material air inlet channel is a laminated board structure, and is also required to be connected with a bulkhead, a reinforcing rib and the like during assembly. The connection forms of the composite material structure mainly comprise 3 types: glue joints, mechanical joints and hybrid joints. Different connection forms have different problems, such as high dispersivity of adhesive joint strength, difficult transmission of large load, high environmental impact of adhesive joint performance and ageing problem; the mechanical connecting hole has concentrated circumferential stress, weight is increased, and the pneumatic characteristic of the structure is poor, and the structure is contacted with the composite material to generate galvanic corrosion; the weight and cost of the hybrid connection increases significantly. Composite structures are subject to not only complex loads, but also severe environmental factors, which can result in changes or damage to the composite structure's properties. The connection structure is the most vulnerable area of the composite structure to damage or failure, and studies have shown that approximately 80% of structural failures are caused by the connection structure, and the design of the composite connection structure is a bottleneck that restricts the further application of the composite in the aircraft structure. Meanwhile, the split structure cannot be used for structural layout of a modern fighter plane.

The invention provides an integral co-curing molding process for an S-shaped air inlet channel made of a multi-bulkhead carbon fiber composite material, which can complete integral co-curing molding of a plurality of bulkhead and the air inlet channel only by one curing process. The subsequent connection work is not needed, various problems and risks in connection of the bulkhead and the air inlet channel are avoided, and the assembly period and the cost are reduced.

Disclosure of Invention

The invention discloses an S-shaped air inlet of a multi-bulkhead carbon fiber composite material, which is formed by integrally co-curing a cylinder section skin and a plurality of bulkhead, and the core technology of the invention is to develop a combined paving and curing tool, and realize continuous paving of a plurality of bulkhead layers of the carbon fiber composite material by alternately paving the tool on two sides of the bulkhead of the S-shaped air inlet and integrally co-curing and forming with the cylinder section of the air inlet.

The technical scheme of the invention is as follows:

the integral co-curing and forming process of the S-shaped air inlet channel of the multi-bulkhead carbon fiber composite material comprises the following steps:

step 1, the skin of the cylinder section of the air inlet channel is paved to a preset layer number according to design requirements, and the uncured state is maintained. And integrally transferring the air inlet channel cylinder section skin and the laying tool thereof to the bulkhead forming model frame.

And 2, installing a spacer frame laying tool on the spacer frame molding model frame. And (3) 1/2 of the layer of the skin edge of the laying barrel section and the spacer frame is laid, and after the laying is completed, the spacer frame laying tool is moved down.

The bulkhead laying tool comprises a panel 28, support arms 20 and pin holes 29, wherein the panel 28 is split according to the separating surface of the barrel section, and each split panel 28 is provided with the support arm 20 and is integrally manufactured. Pin holes 29 are provided in the arms 20 for connection to the former frame.

And 3, assembling the bulkhead curing tool on the bulkhead molding model frame. When the bulkhead curing tool is assembled, the bulkhead curing tool is not completely attached to the air inlet channel barrel section, a 5mm assembled gap is reserved, the gap is filled with multiple layers of right trapezoid silicon rubber, the high-temperature volume expansion of the rubber is utilized, the skin at the bottom of the bulkhead curing tool is ensured to obtain enough pressure during curing, the internal quality of a workpiece is ensured, and meanwhile indentation on the surface of the workpiece is avoided.

The bulkhead curing tooling 24 includes a bulkhead curing die 25, a weight reduction groove 26, bolt holes 30, a back plate 27, support arms 20 and pin holes 29. The allowance of 20mm is added on the basis that the side height of the bulkhead curing mold 25 is the bulkhead flanging width, and the profile surface is the bulkhead profile. The parting frame curing mold 25 divides the mold according to the separating surface of the barrel section and the weight of a single mold, and demolding wedge angles with different angles are designed among the parting sections so as to ensure that the tool can be smoothly demolded after curing without damaging a workpiece. After the bulkhead curing mold 25 is formed and connected with a sufficient width and strength, the middle part of the non-working surface is scratched with a weight-reducing groove 26, so that the weight of the tooling is reduced, and the precision and operability of the tooling during integral use are met. Two bolt holes 30 are reserved on each split tooling and are used for being connected with a pin lifter during demolding. The back plate 27 is provided with a plurality of bolt holes 30 for combining the spacer frame forming modules into a large block, so that the accuracy and stability of the spacer frame forming modules in use are ensured. Each block is provided with a plurality of support arms 20 according to the weight of the connecting tool, and pin holes 29 are arranged on the support arms and are used for being connected with the bulkhead forming model frame, so that the position accuracy of each bulkhead is ensured.

And 4, compacting the prepreg exceeding the height of the bulkhead curing mold 25 along the molding surface of the prepreg to the side surface of the prepreg. And filling 0-degree fiber twisted strips at the R angle position formed by the bulkhead blank and the barrel section skin, so that the occurrence of a cavity in the area is avoided.

And 5, paving the rest 1/2 of the spacer frames, 1/2 of the adjacent spacer frames and the layering of the cylinder sections between the two spacer frames on the paved blank in the step 4. And after the number of the laminated layers reaches the design requirement, detaching the bulkhead laminating tool, and installing a bulkhead curing tool for laminating 1/2 bulkhead and a bulkhead laminating tool for the subsequent adjacent bulkhead. And then the laying is carried out successively until the laying of all the bulkhead and the barrel section skins is completed.

And 6, when vacuum packaging is carried out by utilizing the vacuum bags, packaging is carried out in a partition mode, the partition frame is used as an interface, and each section of vacuum bag is spliced and sealed at the position by using a sealing adhesive tape.

The invention has the beneficial effects that: the invention creatively provides a multi-bulkhead carbon fiber composite material S-shaped air inlet integral co-curing molding process, wherein an annular bulkhead is integrally molded, and assembly is not required after block curing; the plurality of the bulkhead frames can realize continuous layering; reserving a 5mm allowance between a spacer frame forming die and a cylinder section skin for filling silicon rubber, and performing spacer frame forming film bottom skin by utilizing thermal expansion of the silicon rubber; the multilayer silicon rubber is stacked in a right trapezoid structure, one side, which is contacted with the bulkhead, is right-angled, the other side is oblique, and meanwhile, the bottom layer silicon rubber is guided by an oblique angle of 30 degrees, so that the silicon rubber is prevented from leaving an indentation on a workpiece. The integral co-curing molding of the plurality of the partition frames and the air inlet channel can be completed only by one curing process, and meanwhile, the continuous layering of the plurality of the partition frames can be realized. The method can be used for co-curing and cementing co-curing of a J-shaped frame, a T-shaped frame, frames with different heights and barrel section structures. Greatly improves the structural performance and the advancement. The connection work in the later period is not needed, various problems and risks in connection of the bulkhead and the air inlet channel are avoided, and the assembly period and the cost are reduced.

Drawings

FIG. 1 is a schematic view of a former frame;

FIG. 2 is a schematic view of a base portion;

FIG. 3 is a schematic view of a front end support spacer;

FIG. 4 is a schematic view of a left and right stop seat assembly;

FIG. 5 is a schematic view of front and rear limiting plates;

FIG. 6 is a schematic view of a rear end support spacer;

FIG. 7 is a schematic view of a portion of the upper frame;

FIG. 8 is a schematic diagram of a former mold;

FIG. 9 is a schematic diagram of a bulkhead curing tooling;

fig. 10 is a schematic diagram of a former lay-up tooling.

In the figure: 1. a base; 2. an upper frame; 3. forming a partition frame forming die; 4. a base; 5. the front end supports the locating rack; 6. the rear end supports the locating rack; 7. a column; 8. a left limit seat and a right limit seat; 9. front and rear limit seats; 10. a front support; 11. a clamp; 12. a long pin; 13. a base table; 14. a limiting block; 15. a limiting plate; 16. a circular limiting ring; 17. limiting clamp; 18. a rear support; 19. a connecting platform; 20. a support arm; 21. square steel; 22. a beam; 23. spacer frame laying tool; 24. curing the bulkhead; 25. curing the spacer frame; 26. a weight-reducing groove; 27. a back plate; 28. a panel; 29. a pin hole; 30. bolt holes.

Detailed Description

The technical scheme of the invention is further described below according to the attached drawings and the embodiments.

1. And (3) paving the air inlet channel skin to a preset layer number, wherein manual paving or automatic wire paving can be selected. The automatic wire laying is better.

2. And (5) preparing a tool. And wiping the spacer frame laying tool and the spacer frame curing tool by using a cleaning agent until the spacer frame laying tool and the spacer frame curing tool are wiped by using clean white rag, and no dirt exists on the spacer frame laying tool and the spacer frame curing tool. After the cleaning, a release agent is applied to the contact position between the spacer curing mold 25 and the prepreg. And the spacer frame laying tool is strictly forbidden to contact with the release agent, so that the prepreg is prevented from being polluted.

3. And (5) assembling a tool. And (3) transferring the air inlet channel skin subjected to laying and tooling thereof to a bulkhead forming tooling frame integrally. The leftmost former lay-up tooling is assembled to the form by pin holes 29 in the arms 20. And simultaneously, the back plate 27 and the spacer frame curing die 25 are connected to form a spacer frame curing tool.

4. And cutting the prepreg. And carrying out height statistics on the distance between the partition frame and the barrel section, and grouping according to different heights. Grouping is based on: the shortest distance between the partition frame and the cylinder section is A, the distance between the partition frame and the cylinder section is S, and n is a grouping coefficient.

n= (S-A)/200, grouping according to grouping coefficients, wherein the regions with n less than or equal to 1 are se:Sup>A group,

n is more than 2 and less than or equal to 3, and the like. Each group of prepregs had a length of a+200n,200mm width and a length direction of 0 ° fiber direction.

5. And (5) laying the spacer frame. During laying, the section of the prepreg cut pieces are firstly laid on the section of the cylinder by taking the section of the cylinder as a reference, and are gradually compacted along the fiber direction until the prepreg cut pieces are laid on the positions of the partition frames. After the current layer barrel section area is fully paved by the prepreg, the area without the prepreg on the bulkhead paving tool is required to be additionally paved by the prepreg unidirectional tape. The lay-up is repeated until 1/2 of the number of the spacer frame lay-up layers.

6. And (5) replacing the tool. And disassembling the bulkhead laying tool, placing 3 layers of silicon rubber in a right trapezoid along the root of the bulkhead at one side where the bulkhead curing tool is to be installed, wherein one side contacting the bulkhead is right-angled and is clung to the bulkhead. The width of the uppermost layer of silicon rubber is +20mm of the forming die of the partition frame, each layer is 8-12mm wider than the previous layer, and the side of the bottommost layer of silicon rubber, which is far away from the partition frame, is trimmed with a 30-degree bevel angle at the edge by a wallpaper knife. Preventing the silicone rubber edges from leaving an impression on the part after curing. The bulkhead curing tooling is mounted on the frame, and the adjacent bulkhead laying tooling is also mounted.

7. Compacting the blank. Compacting the blank of which the laid spacer frame is higher than the spacer frame curing tool on the side face of the spacer frame curing tool, wherein the folded part is arranged, and the folded part is required to be cut off, so that redundant blanks are removed. And the missing part is required to be additionally paved with prepreg with equal thickness, and the prepreg is spliced in a butt joint mode.

8. The prepregs are laid up. The remaining 1/2 of the former is laid up, the next 1/2 of the former and the barrel section therebetween. And after the laying is completed, the bulkhead laying tool is disassembled, and a bulkhead curing tool for laying 1/2 bulkhead and a next bulkhead laying tool are installed.

9. And (5) placing process auxiliary materials. Because the bulkhead is vertical to the ground, the process auxiliary materials cannot be naturally placed. It is fixed to the non-working face of the former by a pressure sensitive adhesive tape.

10. And (3) manufacturing a vacuum bag, namely firstly manufacturing one end of the vacuum bag, placing the two ends of the cylinder section to naturally hang down, and bonding the two ends together by using a sealing rubber strip under the cylinder section. One side of the surface protection paper is stuck on the cylinder section forming die by using a sealing adhesive tape, and the surface protection paper is not torn off after the sealing adhesive tape is stuck on the other end of the surface protection paper.

11. And (5) making a vacuum bag between the adjacent partition frames. After repeating step 9, the protective paper of step 10 is removed and the side adjacent to the vacuum produced at this time is bonded. The pasting position is at the position of the bulkhead and is provided with the support arms 20, and the vacuum bags at two sides are respectively stuck on one surface of the support arms 20 instead of mutually sticking the vacuum bags, so that a sealing adhesive tape is required to be added on the support arms 20, and the sealing effect is ensured.

12. The above steps 9.10 and 11 are repeated until all the formers and tube sections are covered by the vacuum bag. The number of vacuum bags is the number of the partition frames +1.

13. And (3) integrally placing the tool into an autoclave for curing.

14. And (5) demolding. The back plate 27 on the bulkhead curing process is removed first, and then the part of the wedge angle pressed on the other part is firstly taken according to the demolding wedge angle. Two bolt holes 30 on the tool are connected simultaneously by two pin lifting devices, and two people strike the tool simultaneously, so that the tool can be withdrawn in parallel. In this way, the former curing mold 25 is successively removed.

The bulkhead forming model frame comprises a base 1, an upper frame 2 and a bulkhead forming die 3.

The base 1 comprises a base 4, a front end supporting and positioning frame 5, a rear end supporting and positioning frame 6 and an upright post 7.

The base 4 is of a double-layer grid structure, the front end and the rear end of the base are trapezoidal, and the middle section of the base is rectangular. The front end supporting and positioning frame 5 and the rear end supporting and positioning frame 6 are respectively arranged above the front end and the rear end of the base 4.

The front end supporting and positioning frame 5 comprises a front supporting table 10, a left limiting seat 8, a right limiting seat 8 and a front limiting plate 9 which are arranged on the front supporting table 10; the left and right limiting seats 8 comprise two parts, one part is a clamp 11 with a round inside and a trapezoid outside bottom side, and a long pin 12 is arranged on the clamp and used for positioning with a barrel section tool; the other part is a base table 13, two fixed limiting blocks 14 are arranged on the base table 13, and the opposite surfaces of the two limiting blocks 14 are inclined surfaces matched with the bottom of the clamp 11. The front and rear limiting plates 9 comprise limiting plates 15 and circular limiting rings 16, wherein the limiting plates 15 are flat plates, a hole is formed in the center of each limiting plate, and the circular limiting rings 16 are arranged in the holes. The circular limiting ring 16 is a circular boss with a hole in the center, the protruding section at one end of the boss extends out of the limiting plate by 15 mm in height, and the diameter of the protruding section is matched with the barrel section tool; the other end plays a role in connection, is connected with the limiting plate 15 by bolts, and can be taken down from one surface of the limiting plate 15 far away from the left and right limiting seats 8. The front supporting table 10 is of a rectangular plate frame structure, screw holes connected with the left and right limiting seats 8, the front and rear limiting plates 9 and the base 4 are formed in the front supporting table 10, and the height of the front supporting table 10 can ensure a clearance of at least 400mm between the combined partition frame forming die 3 and the base 4.

The rear end supporting and positioning frame 6 comprises a limiting clamp 17 and a rear supporting table 18, wherein the upper part of the limiting clamp 17 is detachable, the bottom of the limiting clamp 17 is connected with the upper part, the inner diameter of the limiting clamp is matched with the barrel section tool, and the bottom of the limiting clamp 17 is fixed with the rear supporting table 18. The rear supporting table 18 is of a square steel frame structure, the height of the rear supporting table 18 is required to be higher than that of the front supporting table 10, and meanwhile, the tool angle of the barrel section is adjusted with the front supporting table 10, so that the frame spacing posture is ensured to be perpendicular to the ground.

The left side and the right side of the base 4 are symmetrically provided with upright posts 7, and the number of the upright posts 7 on each side is the same as that of the bulkhead. The upright 7 comprises a frame, a connecting platform 19 and arms 20. The connecting platform 19 is located at the top end of the frame and is used for being combined with the upper frame 2, 4 holes are formed in the connecting platform 19, and the connecting platform 19 is located at four vertexes of a rectangle. Two diagonal positions are one group, one group is a pin hole and is used for positioning the connecting platform 19; the other group is bolt holes for connection of two connection platforms 19. The support arm 20 connected with the partition frame forming die 3 is arranged on the inner side of the frame of the upright post 7. The connection area between the frame and the inner side of the base 4 is arc-shaped, so that the connection area can be increased to the greatest extent, and the stability of the upright post 7 is improved. At the same time, the distance between the spacer frame and the spacer frame forming die 3 can be ensured, and enough operation space is ensured.

The upper frame 2 takes the form of square steel pipes 21 connected to a number of beams 22. The number of beams 22 is the same as the number of formers. The beam 22 is arc-shaped on the inner side and trapezoid on the outer side, and is partially provided with symmetrical weight reducing ports and is connected into a whole through square steel pipes 21. Each beam 22 is provided with a support arm 20 connected to the former. The bottom of the upper frame 2 is provided with a connecting platform 19 connected with the top end of the upright post 7.

The spacer forming die 3 comprises a spacer laying tool 23 and a spacer curing tool 24. The bulkhead laying tool 23 is manufactured in a split mode, and each split is provided with a support arm 20 connected with the upright post 7 or the upper frame 2. For laying half-plies of the formers. The bulkhead curing tooling 24 comprises two parts, wherein one part is a bulkhead curing die 25, the height of the side edge of the bulkhead curing die 25 is the height of a bulkhead flanging and 20mm allowance, and the appearance surface is a bulkhead molded surface. The parting frame curing mold 25 is of a split structure, and demolding wedge angles of different angles of the tool are designed among the split structures. The tool can be smoothly demolded after being cured, and a workpiece cannot be damaged. After the bulkhead curing mold 25 is formed and connected with a sufficient width and strength, the middle part of the non-working surface is scratched with a weight-reducing groove 26, so that the weight of the tooling is reduced, and the precision and operability of the tooling during integral use are met. Two bolt ports are reserved on each split tool and are connected with a pin lifter when the split tool is used for demolding. The other part of the bulkhead curing tool 24 is a back plate 27 which is used for combining the bulkhead forming modules into a large block, so that the accuracy and stability of the bulkhead forming modules in use are ensured, and the back plate 27 is provided with a support arm 20 which is connected with the support arm 20 of the upright post 7 or the upper frame 2, so that the position accuracy of each bulkhead is ensured.

In the bulkhead laying tool, the panel 28 and the support arm 20 are made of aluminum. The bulkhead solidification tool adopts common steel.

Claims (1)

1. The integral co-curing and forming process of the S-shaped air inlet of the multi-bulkhead carbon fiber composite material is characterized by comprising the following steps of:

step 1, paving an air inlet channel barrel section skin to a preset layer number according to design requirements, and keeping an uncured state; transferring the whole air inlet channel cylinder section skin and the paving tool thereof to a bulkhead forming model frame;

step 2, installing a spacer frame laying tool on a spacer frame molding model frame; 1/2 of the covering edge of the laying barrel section and the spacer frame are laid, and after the laying is completed, the spacer frame laying tool is moved down;

the bulkhead laying tool comprises a panel (28), support arms (20) and pin holes (29), wherein the panel (28) is split according to the separating surface of the barrel section, and each split panel (28) is provided with the support arm (20) and is integrally manufactured; the pin hole (29) is arranged on the support arm (20) and is used for being connected with the bulkhead forming model frame;

step 3, assembling a bulkhead curing tool on a bulkhead molding model frame; when the bulkhead curing tool is assembled, the bulkhead curing tool is not completely attached to the air inlet channel barrel section, a 5mm assembled gap is reserved, the gap is filled with multiple layers of right trapezoid silicon rubber, the high-temperature volume expansion of the rubber is utilized, the skin at the bottom of the bulkhead curing tool is ensured to obtain enough pressure during curing, the internal quality of a workpiece is ensured, and meanwhile, indentation on the surface of the workpiece is avoided;

the bulkhead molding model frame comprises a base (1), an upper frame (2) and a bulkhead molding die (3); the spacer forming die (3) comprises a spacer laying tool (23) and a spacer curing tool (24);

the bulkhead curing tool (24) comprises a bulkhead curing die (25), a weight-reducing groove (26), bolt holes (30), a back plate (27), a support arm (20) and pin holes (29); the allowance of 20mm is increased on the basis that the side height of the bulkhead curing mold (25) is the bulkhead flanging width, and the profile is the bulkhead profile; dividing the partition frame curing mold (25) according to the separating surface of the barrel section and the weight of a single partition, and designing demolding wedge angles with different angles among the dividing partition plates so as to ensure that the tool can be smoothly demolded after curing without damaging a workpiece; after the bulkhead curing mold (25) is reserved with enough width and strength for molding and connecting, a weight-reducing groove (26) is scratched at the middle part of the non-working surface, so that the weight of the tooling is reduced, and the precision and operability of the whole tooling in use are met; two bolt holes (30) are reserved on each split tool and are used for being connected with a pin lifter during demolding; the backboard (27) is provided with a plurality of bolt holes (30) for combining the partition frame forming die (3) into a large block, so that the accuracy and stability of the partition frame forming die in use are ensured; each block is provided with a plurality of support arms (20) according to the weight of the connecting tool, and pin holes (29) are arranged on the support arms and are used for being connected with the bulkhead forming model frame so as to ensure the position precision of each bulkhead;

step 4, compacting the prepreg exceeding the height of the bulkhead curing mold (25) to the side surface of the prepreg along the molding surface of the molding mold; filling 0-degree fiber twisted strips at the R angle position formed by the bulkhead blank and the barrel section skin, so as to avoid the occurrence of cavities in the area;

step 5, paving 1/2 of the rest of the spacer frames, 1/2 of the adjacent spacer frames and the layering of the cylinder sections between the two spacer frames on the paved blank in the step 4; after the number of the laminated layers reaches the design requirement, detaching the bulkhead laminating tool, and installing a bulkhead curing tool for laminating 1/2 bulkhead and a bulkhead laminating tool for the subsequent adjacent bulkhead; then, the laying is carried out successively until the laying of all the spacer frames and the cylinder section skins is completed;

and 6, when vacuum packaging is carried out by utilizing the vacuum bags, packaging is carried out in a partition mode, the partition frame is used as an interface, and each section of vacuum bag is spliced and sealed at the position by using a sealing adhesive tape.