Automatic forming method for T-shaped stringer in net size wet state

Abstract

The invention provides an automatic forming method for a net-size wet-state T-shaped stringer. The automatic forming method comprises the steps that composite material wet-state flat plate paving is completed on an automatic belt paving machine; cutting the composite material wet state flat plate into a composite material net size flat plate blank of the T-shaped stringer; at least one composite core mold is placed on the long-strip-shaped male mold at the corresponding position of the pre-forming mold base to form a set of combined mold, and the combined mold is hoisted and placed on a working table top of an L-shaped composite stringer forming device; the composite material net-size flat plate blank is transferred and placed in horizontal upper groove bodies of the L-shaped step grooves in the two sides of the corresponding composite material core mold; bending and deforming the composite material net-size flat plate blank by adopting an L-shaped composite material stringer forming device to form an L-shaped stringer prefabricated body; and the multiple combined molds and the L-shaped stringer prefabricated bodies 7 are integrally transferred to a folding assembly to be folded, and therefore every two adjacent L-shaped stringer prefabricated bodies are bonded and attached to form the net-size wet-state T-shaped stringer.

Description

Technical Field

[0001] This invention belongs to the field of composite material T-shaped stiffened wall panel manufacturing technology, and specifically refers to an automatic forming method for a wet T-shaped stringer with net dimensions. Background Technology

[0002] Composite material T-string stiffened panels, as a crucial aircraft structure, have broad research and application value. Co-bonding is the most mature molding method for manufacturing stiffened panels. This method requires first curing the wet composite material T-string, removing edge excess, then precisely aligning and bonding it with the panel, followed by curing to form the composite material T-string stiffened panel. Co-bonding demands high bonding quality and precision, posing potential quality risks, and involves multiple curing cycles, complex processing steps, and high manufacturing costs. With the improvement of aircraft performance, the application of composite material T-string stiffened panels in aircraft is increasing, leading to a significant increase in demand from aircraft manufacturers. Consequently, the manufacturing process for composite material T-string stiffened panels is gradually shifting from co-bonding to co-curing.

[0003] The co-curing process involves directly and precisely butt-jointing wet-state composite material T-shaped stringers and wet-state composite material skins to form wet-state composite material T-shaped stiffened panels, followed by integral curing. Compared to co-adhesion bonding, co-curing only requires one curing step, improving the structural strength of the product. Furthermore, the composite material T-shaped stringers require no further processing after curing, resulting in high forming efficiency and low manufacturing costs. However, since the T-shaped stringers cannot be further processed after co-curing with the skin, wet-state T-shaped stringers must be manufactured using net-size molding. Currently, the main method for molding net-size wet-state T-shaped stringers is manual installation, which is inefficient, labor-intensive, and makes it difficult to guarantee consistent batch quality. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems by providing an automatic forming method for wet T-shaped stringers of net size, thereby addressing the issues of low efficiency, high labor intensity, and difficulty in ensuring consistent batch production quality in the co-curing process of reinforced T-shaped stringers of composite materials.

[0005] The technical solution of this invention is as follows: This invention provides an automatic forming method for a wet T-shaped stringer with net dimensions. The equipment used to implement the automatic forming method for a wet T-shaped stringer with net dimensions includes: an automatic tape laying machine 1, a preforming mold base 3, an L-shaped composite stringer forming device 4, a composite core mold 5, and an mating assembly 6; the forming method includes: Step 1: Using automatic tape laying machine 1, according to the design layup requirements of the T-shaped stringer, the same layup of the T-shaped stringer is merged, and the composite material wet flat plate laying is completed on the automatic tape laying machine 1. Step 2: Set the cutting program and use the ultrasonic cutter on the automatic tape laying machine 1 to cut the wet composite material flat sheet into a T-shaped stringer composite material net size flat sheet blank 2. Step 3: Place at least one composite core mold 5 on the corresponding long strip punch on the preforming mold base 3 to form a set of combined molds, and then hoist the combined molds onto the worktable 14 of the L-shaped composite stringer forming device 4; Step 4: Transfer the cut composite material net size flat blank 2 and place it in the horizontal upper groove of the L-shaped stepped groove on both sides of the corresponding composite core mold 5. The positioning of the composite material net size flat blank 2 is achieved by the groove structure of the L-shaped stepped groove on both sides of the composite core mold 5. Step 5: Use pressure-sensitive adhesive tape to fix the composite material blank 2 in the L-shaped stepped groove of the composite core mold 5 to prevent the composite material blank 2 from slipping. Then, lay a non-porous isolation film on the upper surface of the composite material blank 2 to prevent foreign objects from contaminating the blank. Step 6: Start the L-shaped composite stringer forming device 4 and perform thermal insulation molding according to the set program. Bend and deform the flat blank 2 of the composite material net size to form the L-shaped stringer preform 7 in the L-shaped groove of each combination mold. Step 7: After the thermal insulation membrane is formed, the multiple combined molds and the L-shaped stringer preforms 7 formed in the L-shaped grooves are transferred as a whole to the mating assembly 6. The mating assembly 6 mates each combined mold and the L-shaped stringer preforms 7 on both sides of the top of each combined mold, thereby bonding and attaching two adjacent L-shaped stringer preforms 7 to form a T-shaped stringer in a wet state with net dimensions.

[0006] Optionally, in the above-described method for automatic forming of a wet T-shaped stringer with net dimensions, Each of the composite core molds 5 is placed on the elongated punch at the corresponding position on the upper end of the preforming mold base 3, and is used to position and support the flat blank 2 of the composite material net size. The composite core mold 5 is a gate-shaped structure made of composite material. Its upper surface profile is consistent with the profile at the corresponding position of the inner wall of the skin. L-shaped stepped grooves are provided at the two top corners of the gate-shaped structure. The profile and size of the L-shaped stepped grooves are consistent with the T-shaped stringer. An inverted U-shaped positioning notch is opened at the bottom middle position of the two side walls of the composite core mold 5.

[0007] Optionally, in the above-described method for automatic forming of a wet T-shaped stringer with net dimensions, the preforming mold base 3 is configured as a long box-shaped structure made of aluminum-magnesium alloy, which is placed on the upper end face of the vacuum worktable assembly 11 of the L-shaped composite stringer forming device 4; the upper surface of the preforming mold base 3 fits into the inner surface of the corresponding composite core mold 5, and a raised positioning platform in the middle is provided to cooperate with the inverted U-shaped positioning notch on the composite core mold 5.

[0008] Optionally, in the above-described method for automatic forming of a wet T-shaped stringer with net dimensions, the L-shaped composite stringer forming device 4 includes: a lifting module 8, a heating component 9, a diaphragm component 10, and a vacuum worktable component 11. The lifting module 8 includes two sets of lifting mechanisms fixedly placed on the ground and arranged opposite each other. A heating component 9 is installed between the two sets of lifting mechanisms, and the heating component 9 can move precisely in the vertical direction under the drive of the lifting module 8. The diaphragm component 10 is fixedly arranged on the lower end face of the heating component 9. The vacuum worktable component 11 is placed on the ground and moves to directly below the diaphragm component 10 during operation.

[0009] Optionally, in the above-described automatic forming method for a wet T-shaped stringer with net dimensions, the thermal insulation forming method performed by the L-shaped composite stringer forming device 4 in step six is ​​as follows: The L-shaped composite stringer forming device 4 is used to control the lifting module 8 to move downwards, so that the diaphragm assembly 10 covers the upper surface of the vacuum worktable assembly 11, so that the diaphragm assembly 10 and the vacuum worktable assembly 11 are completely in contact and form a closed space, and seal multiple combined molds and composite material net-size flat blanks 2 fixed on both sides of the upper end of each combined mold in the closed space; by controlling the heating component 9 to heat the closed space, and controlling the vacuum worktable assembly 11 to evacuate the closed space, the elastic membrane 13 in the diaphragm assembly 10 deforms and bends the composite material net-size flat blanks 2 to form L-shaped stringer preforms 7 in the L-shaped grooves of each combined mold, thereby realizing thermal diaphragm forming.

[0010] Optionally, in the above-described method for automatic forming of a wet T-shaped stringer with net dimensions, The diaphragm assembly 10 includes: a fixed frame 12 and an elastic membrane 13; the fixed frame 12 is a hollow U-shaped structure, and the elastic membrane 13 is a rectangular rubber membrane with a certain elastic modulus, and the elastic membrane 13 is fixed to the lower end face of the fixed frame 12.

[0011] Optionally, in the above-described method for automatic forming of a wet T-shaped stringer with net dimensions, The vacuum worktable assembly 11 includes: a worktable surface 14, a sealing ring 15, a support frame 16, and a vacuum generator 17; wherein, the worktable surface 14 is configured as a rectangular worktable surface, and the central area is divided into an array of rectangular block structures by multiple through slots opened horizontally and vertically, and a semi-circular cross-section groove is opened around its upper end surface for setting the sealing ring 15 in the groove. The support frame 16 is fixedly installed at the lower part of the workbench 14 to support the workbench 14. Multiple vacuum generators 17 are spaced apart inside the support frame 16. Each vacuum generator 17 is connected to the workbench 14 through an air pipe to draw air from the upper part of the workbench 14 through the through groove of the workbench 14 and discharge it from the bottom of the support frame 16.

[0012] Optionally, in the above-described automatic forming method for a wet T-shaped stringer with net dimensions, the mating assembly 6 includes: a mating table 18 and a servo electric cylinder 19. The upper surface of the mating platform 18 is a plane, and multiple longitudinally arranged servo electric cylinders 19 are arranged parallel to each other along the length direction on the upper surface of the mating platform 18 to provide pressure for the mating of multiple L-shaped stringer prefabricated bodies 7 and combined molds; and a positioning block is provided on one side of the upper surface of the mating platform 18, which serves as the reference surface for the mating and pressing of multiple combined molds.

[0013] Optionally, in the above-described automatic forming method for a wet T-shaped stringer with net dimensions, the thermal insulation film forming process in the step flow includes: S1, control the heating component 9 in the L-shaped composite stringer forming device 4 to heat at a heating rate of 4℃ / min, heat to 70℃, and hold for 10min; S2, control the lifting module 8 to drive the diaphragm assembly 10 to descend at a rate of 1-4 mm / s, cover the upper surface of the vacuum worktable assembly 11, and completely fit it to form a closed space, and multiple combined molds and the composite material net-size flat blanks 2 fixed on both sides of the upper end of each combined mold are in this closed space. S3, maintain the preforming temperature, control the vacuum worktable assembly 11 to slowly apply vacuum at a rate of 3 kpa / min until the composite material net-size flat blank 2 is completely in contact with the composite core mold 5 on the preforming mold base 3 to form an L-shaped stringer preform 7, and then continue to apply vacuum at 20 kpa / min until the vacuum degree reaches 0.06 MPa, and maintain for 10 min. S4, maintain maximum vacuum, control the heating component 9 to cool down at a rate not exceeding 4℃ / min, until the temperature is ≤40℃; S5, control the vacuum stage assembly 11 to unload the vacuum; S6, control the lifting module 8 to drive the diaphragm assembly 10 to move upward, open the closed space, and move the multiple combined molds and the L-shaped stringer prefabricated body 7 formed on both sides of the upper end of each combined mold from the vacuum workbench assembly 11 to the next station. The total time from heating the composite material net-size flat blank 2 to cooling it to room temperature shall not exceed 120 minutes.

[0014] The beneficial effects of this invention are as follows: This invention provides an automatic forming method for T-shaped stringers in a wet state with net dimensions. This method uses automatic tape laying technology to lay out composite material flat blanks, and then uses an ultrasonic cutter to cut the blanks to the required net dimensions. A combined mold consisting of a composite core mold and a pre-forming mold base is used to complete the thermal insulation forming of the T-shaped stringers with net dimensions. When T-shaped stringers are formed using automatic tape laying combined with thermal insulation technology, problems such as poor compaction, fiber wrinkling and buckling, and unstable batch production quality caused by manual laying are improved. It has advantages such as improved product radius corner quality, interlayer density, and surface quality. Regarding the automatic forming method for wet T-shaped stringers with net dimensions provided by this invention, this invention also relates to specialized equipment. During the thermal diaphragm forming process of the L-shaped composite stringer forming device 4 of this equipment, the diaphragm assembly 10 and the vacuum worktable assembly 11 are completely fitted together, forming a closed space. Multiple combined molds and composite material flat blanks 2 fixed on both sides of the upper end of each combined mold are sealed within this closed space. By controlling the heating assembly 9 to heat this closed space and controlling the vacuum worktable assembly 11 to evacuate the closed space, the elastic membrane 13 in the diaphragm assembly 10 deforms, bending and deforming the composite material flat blanks 2 to form L-shaped stringer preforms 7 within the L-shaped grooves of each combined mold. This invention, using the aforementioned equipment to implement the automatic forming method for wet T-shaped stringers with net dimensions, achieves a fully automated forming scheme. This not only significantly improves product quality but also reduces manufacturing costs and increases forming efficiency. These advantages make the application of automation technology in the manufacturing of composite reinforced panels particularly important and can be directly extended to the assembly of similar parts and components in other industries. Attached Figure Description

[0015] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0016] Figure 1 A schematic diagram of the equipment used to implement the automatic forming method of wet T-shaped stringers with net dimensions; Figure 2 This is a schematic diagram of the composite core mold in an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the preform mold base in an embodiment of the present invention; Figure 4 This is a schematic cross-sectional view of the composite material flat blank and the combined mold in an embodiment of the present invention; Figure 5 This is a schematic cross-sectional view of the L-shaped long truss prefabricated body and the combined mold in an embodiment of the present invention; Figure 6 This is a schematic diagram of the structure of the L-shaped composite stringer forming device in an embodiment of the present invention; Figure 7 This is a cross-sectional schematic diagram of the L-shaped composite stringer forming device in an embodiment of the present invention; Figure 8 This is a schematic diagram of the mating component structure in an embodiment of the present invention.

[0017] Explanation of markings in the diagram: 1 Automatic tape laying machine, 2 Composite material net-size flat blank, 3 Preform mold base, 4 L-type composite stringer forming device, 5 Composite core mold, 6 Matching assembly, 7 L-type stringer preform, 8 Lifting module, 9 Heating assembly, 10 Diaphragm assembly, 11 Vacuum worktable assembly, 12 Fixing frame, 13 Elastic membrane, 14 Worktable surface, 15 Sealing ring, 16 Support frame, 17 Vacuum generator, 18 Matching table surface, 19 Servo electric cylinder. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

[0019] As explained in the background section, compared to co-bonding, co-curing improves the structural strength of the composite product by requiring only one curing cycle. Furthermore, the composite T-string requires no further processing after curing, resulting in high molding efficiency and low manufacturing costs. However, since the T-string cannot be further processed after co-curing with the skin, the wet T-string must be manufactured using net-size molding. Currently, the main molding method for wet T-strings is manual installation, which is inefficient, labor-intensive, and makes it difficult to guarantee consistent batch quality.

[0020] Based on the need for co-curing processes in composite material T-shaped stiffened panels, the development and promotion of efficient, low-cost, and highly stable net-size wet-state T-shaped stiffening molding technology is a current trend. However, current research on automated molding devices and methods for composite material net-size wet-state T-shaped stiffening panels is limited, at a low level, and lacks application examples, severely hindering the overall manufacturing process of composite material T-shaped stiffened panels. Therefore, to meet production needs, this invention provides an automated molding method for net-size wet-state T-shaped stiffening panels and proposes the device used in this molding method.

[0021] The present invention provides the following specific embodiments, which can be combined with each other. For the same or similar concepts or processes, they may not be described again in some embodiments.

[0022] This invention provides an automatic forming method for a wet T-shaped stringer with net dimensions, see below. Figures 1 to 5 As shown in the embodiment of the present invention, the equipment used to implement the automatic forming method of the wet T-shaped stringer in net dimensions includes: an automatic tape laying machine 1, a preforming mold base 3, an L-shaped composite stringer forming device 4, a composite core mold 5, and an mating assembly 6. The automatic forming method of the wet T-shaped stringer in net dimensions provided by the present invention specifically includes the following steps: Step 1: Using automatic tape laying machine 1, according to the design layup requirements of the T-shaped stringer, the same layup of the T-shaped stringer is merged, and the composite material wet flat plate laying is completed on the automatic tape laying machine 1. Step 2: Set the cutting program and use the ultrasonic cutter on the automatic tape laying machine 1 to cut the wet composite material flat sheet into a T-shaped stringer composite material net size flat sheet blank 2. Step 3: Place at least one composite core mold 5 on the corresponding long strip punch on the preforming mold base 3 to form a set of combined molds, and then hoist the combined molds onto the worktable 14 of the L-shaped composite stringer forming device 4; Step 4: Transfer the cut composite material net size flat blank 2 and place it in the horizontal upper groove of the L-shaped stepped groove on both sides of the corresponding composite core mold 5. The positioning of the composite material net size flat blank 2 is achieved by the groove structure of the L-shaped stepped groove on both sides of the composite core mold 5. Step 5: Use pressure-sensitive adhesive tape to fix the composite material blank 2 in the L-shaped stepped groove of the composite core mold 5 to prevent the composite material blank 2 from slipping. Then, lay a non-porous isolation film on the upper surface of the composite material blank 2 to prevent foreign objects from contaminating the blank. Step 6: Start the L-shaped composite stringer forming device 4 and perform thermal insulation molding according to the set program. Bend and deform the flat blank 2 of the composite material net size to form the L-shaped stringer preform 7 in the L-shaped groove of each combination mold. Step 7: After the thermal insulation membrane is formed, the multiple combined molds and the L-shaped stringer preforms 7 formed in the L-shaped grooves are transferred as a whole to the mating assembly 6. The mating assembly 6 mates each combined mold and the L-shaped stringer preforms 7 on both sides of the top of each combined mold, thereby bonding and attaching two adjacent L-shaped stringer preforms 7 to form a T-shaped stringer in a wet state with net dimensions.

[0023] Based on the automatic forming method for wet T-shaped stringers with net dimensions provided in this embodiment of the invention, a dedicated device is designed in this embodiment, namely... Figure 1 , Figures 6 to 8 The equipment shown is for implementing an automated forming method for wet T-shaped stringers with net dimensions.

[0024] In one implementation of this invention, see [link to relevant documentation]. Figure 2 As shown, in this embodiment of the invention, each composite core mold 5 is placed on the corresponding preform mold base 3 to position and support the composite material net size flat blank 2. The composite core mold 5 is a gate-shaped structure made of composite material. Its upper surface profile is consistent with the profile of the corresponding position of the inner wall of the skin. L-shaped step grooves are provided at the two top corners of the gate-shaped structure. The profile and size of the L-shaped step grooves are consistent with the T-shaped stringer. An inverted U-shaped positioning notch is opened at the bottom middle position of the two side walls of the composite core mold 5.

[0025] In one implementation of this invention, see [link to relevant documentation]. Figure 3 As shown, in this embodiment of the invention, the preforming mold base 3 is set as a long box-shaped structure made of aluminum-magnesium alloy, which is placed on the upper end face of the vacuum worktable assembly 11 of the L-shaped composite stringer forming device 4. The upper end face of the preforming mold base 3 is provided with a long strip-shaped punch that fits with the inner surface of the corresponding composite core mold 5. Each long strip-shaped punch has a raised positioning platform in the middle that matches the inverted U-shaped positioning notch on the corresponding composite core mold 5.

[0026] In one implementation of this invention, see [link to relevant documentation]. Figure 6 , 7 As shown, the L-shaped composite stringer forming device 4 in this embodiment of the invention includes: a lifting module 8, a heating component 9, a diaphragm component 10, and a vacuum worktable component 11. In this implementation, the lifting module 8 includes two sets of lifting mechanisms fixedly placed on the ground and arranged opposite each other. The heating component 9 is installed between the two sets of lifting mechanisms, and the heating component 9 can move precisely in the vertical direction under the drive of the lifting module 8. The diaphragm component 10 is fixedly arranged on the lower end face of the heating component 9. The vacuum worktable component 11 is placed on the ground and moves to directly below the diaphragm component 10 during operation.

[0027] Based on the structural form of the L-shaped composite stringer forming device 4 in this implementation method, the method by which the L-shaped composite stringer forming device 4 performs thermal insulation film forming in step six above is as follows: By controlling the lifting module 8 to move downward, the diaphragm assembly 10 covers the upper surface of the vacuum worktable assembly 11, so that the diaphragm assembly 10 and the vacuum worktable assembly 11 are completely in contact and form a closed space, sealing multiple combined molds and the composite material net-size flat blanks 2 fixed on both sides of the upper end of each combined mold within the closed space; by controlling the heating assembly 9 to heat the closed space and controlling the vacuum worktable assembly 11 to evacuate the closed space, the elastic membrane 13 in the diaphragm assembly 10 deforms and bends the composite material net-size flat blanks 2, so as to form an L-shaped stringer preform 7 in the L-shaped groove of each combined mold, thereby realizing the thermal diaphragm forming.

[0028] In specific implementation, the diaphragm assembly 10 is fixed to the lower part of the heating assembly 9. The diaphragm assembly 10 includes a fixed frame 12 and an elastic membrane 13. The fixed frame 12 is a hollow U-shaped structure, and the elastic membrane 13 is a rectangular rubber membrane with a certain elastic modulus. The elastic membrane 13 is fixed to the lower surface of the fixed frame 12.

[0029] In specific implementation, the vacuum worktable assembly 11 includes: a worktable surface 14, a sealing ring 15, a support frame 16, and a vacuum generator 17. The worktable surface 14 is a rectangular worktable surface, and the central area is divided into an array of rectangular blocks by multiple horizontal and vertical through slots. A semi-circular cross-section U-shaped groove is formed around the upper end face for setting the sealing ring 15 in the U-shaped groove. In addition, the support frame 16 is fixedly set at the lower part of the worktable surface 14 to support the worktable surface 14. Multiple vacuum generators 17 are spaced apart inside the support frame 16. Each vacuum generator 17 is connected to the worktable surface 14 through an air pipe to draw air from the upper part of the worktable surface 14 through the through slots and discharge it from the bottom of the support frame 16.

[0030] In one implementation of this invention, such as Figure 1 and Figure 8 As shown, the mating assembly 6 includes: a mating table 18 and a servo electric cylinder 19; The upper surface of the mating platform 18 is a plane, and multiple longitudinally arranged servo electric cylinders 19 are arranged parallel to each other along the length direction on the upper surface of the mating platform 18 to provide pressure for the mating of multiple L-shaped stringer prefabricated bodies 7 and combined molds; and a positioning block is provided on one side of the upper surface of the mating platform 18, which serves as the reference surface for the mating and pressing of multiple combined molds.

[0031] In one embodiment of the present invention, the thermal insulation film forming process in step six includes: S1, control the heating component 9 in the L-shaped composite stringer forming device 4 to heat at a heating rate of 4℃ / min, heat to 70℃, and hold for 10min; S2, control the lifting module 8 to drive the diaphragm assembly 10 to descend at a rate of 1-4 mm / s, cover the upper surface of the vacuum worktable assembly 11, and completely fit it to form a closed space, and multiple combined molds and the composite material net-size flat blanks 2 fixed on both sides of the upper end of each combined mold are in this closed space. S3, maintain the preforming temperature, control the vacuum worktable assembly 11 to slowly apply vacuum at a rate of 3 kpa / min until the composite material net-size flat blank 2 is completely in contact with the composite core mold 5 on the preforming mold base 3 to form an L-shaped stringer preform 7, and then continue to apply vacuum at 20 kpa / min until the vacuum degree reaches 0.06 MPa, and maintain for 10 min. S4, maintain maximum vacuum, control the heating component 9 to cool down at a rate not exceeding 4℃ / min, until the temperature is ≤40℃; S5, control the vacuum stage assembly 11 to unload the vacuum; S6, control the lifting module 8 to drive the diaphragm assembly 10 to move upward, open the closed space, and move the multiple combined molds and the L-shaped stringer prefabricated body 7 formed on both sides of the upper end of each combined mold from the vacuum worktable assembly 11 to the next station.

[0032] It should be noted that during the above-mentioned thermal insulation film molding process, the total time from the start of heating to cooling to room temperature of the composite material net-size flat blank 2 should not exceed 120 minutes.

[0033] This invention provides an automated method for forming T-shaped stringers in a wet state with net dimensions. The method involves automatically laying out a composite material flat blank using tape laying technology, and then cutting the blank to the required net dimensions using an ultrasonic cutter. A combined mold consisting of a composite core mold and a pre-forming mold base is used to complete the thermal insulation forming of the T-shaped stringer to net dimensions. When T-shaped stringers are formed using automated tape laying combined with thermal insulation technology, problems such as poor compaction, fiber wrinkling and buckling, and unstable batch production quality caused by manual laying are improved. This method offers advantages such as improved product radius corner quality, interlayer density, and surface quality. Regarding the automatic forming method for wet T-shaped stringers with net dimensions provided by this invention, this invention also relates to specialized equipment. During the thermal diaphragm forming process of the L-shaped composite stringer forming device 4 of this equipment, the diaphragm assembly 10 and the vacuum worktable assembly 11 are completely fitted together, forming a closed space. Multiple combined molds and composite material flat blanks 2 fixed on both sides of the upper end of each combined mold are sealed within this closed space. By controlling the heating assembly 9 to heat this closed space and controlling the vacuum worktable assembly 11 to evacuate the closed space, the elastic membrane 13 in the diaphragm assembly 10 deforms, bending and deforming the composite material flat blanks 2 to form L-shaped stringer preforms 7 within the L-shaped grooves of each combined mold. This invention, using the aforementioned equipment to implement the automatic forming method for wet T-shaped stringers with net dimensions, achieves a fully automated forming scheme. This not only significantly improves product quality but also reduces manufacturing costs and increases forming efficiency. These advantages make the application of automation technology in the manufacturing of composite reinforced panels particularly important and can be directly extended to the assembly of similar parts and components in other industries.

[0034] While the embodiments disclosed in this invention are as described above, they are merely illustrative of the embodiments to facilitate understanding of the invention and are not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in the form and details of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for automatically forming a wet T-shaped stringer with net dimensions, characterized in that, The equipment used for implementing the automatic forming method of wet T-shaped stringers with net dimensions includes: an automatic tape laying machine (1), a preforming mold base (3), an L-shaped composite stringer forming device (4), a composite core mold (5), and a mating assembly (6); the forming method includes: Step 1: Using an automatic tape laying machine (1), according to the design layup requirements of the T-shaped stringer, merge the same layup of the T-shaped stringer and complete the wet flat laying of the composite material on the automatic tape laying machine (1); Step 2: Set the cutting program and use the ultrasonic cutting knife of the automatic tape laying machine (1) to cut the wet composite material flat plate into T-shaped stringer composite material net size flat plate blanks (2). Step 3: Place at least one composite core mold (5) on the corresponding long strip punch on the preforming mold base (3) to form a set of combined molds, and hoist the combined molds onto the worktable (14) of the L-shaped composite stringer forming device (4); Step 4: Transfer the cut composite material net size flat blank (2) and place it in the horizontal upper groove of the L-shaped stepped groove on both sides of the corresponding composite core mold (5). The positioning of the composite material net size flat blank (2) is achieved by the groove structure of the L-shaped stepped groove on both sides of the composite core mold (5). Step 5: Use pressure-sensitive adhesive tape to fix the composite material net-size flat blank (2) in the L-shaped stepped groove of the composite core mold (5) to prevent the composite material net-size flat blank (2) from slipping, and lay a non-porous isolation film on the upper surface of the composite material net-size flat blank (2) to prevent foreign matter from contaminating the flat blank; Step 6: Start the L-shaped composite stringer forming device (4), perform thermal insulation molding according to the set program, and bend the composite material net size flat blank (2) to form an L-shaped stringer preform (7) in the L-shaped groove of each combination mold. Step 7: After the thermal diaphragm is formed, the multiple combined molds and the L-shaped stringer preforms (7) formed in the L-shaped grooves are transferred as a whole to the mating assembly (6). The mating assembly (6) mates the combined molds and the L-shaped stringer preforms (7) on both sides of the top of each combined mold, thereby bonding and attaching two adjacent L-shaped stringer preforms (7) to form a T-shaped stringer in a wet state with net dimensions.

2. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 1, characterized in that, Each of the composite core molds (5) is placed on the long strip-shaped punch at the corresponding position on the upper end of the preforming mold base (3) to position and support the flat blank (2) of the composite material net size. The composite core mold (5) is a gate-shaped structure made of composite material. Its upper surface profile is consistent with the profile at the corresponding position of the inner wall of the skin. L-shaped step grooves are provided at the two top corners of the gate-shaped structure. The profile and size of the L-shaped step grooves are consistent with the T-shaped stringer. An inverted U-shaped positioning notch is opened at the bottom middle position of the two side walls of the composite core mold (5).

3. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 1, characterized in that, The preformed mold base (3) is a long box-shaped structure made of aluminum-magnesium alloy, which is placed on the upper end face of the vacuum worktable assembly (11) of the L-shaped composite stringer forming device (4); the upper surface of the preformed mold base (3) fits with the inner surface of the corresponding composite core mold (5), and the middle part is provided with a protruding positioning platform that matches the inverted U-shaped positioning notch on the composite core mold (5).

4. The automatic forming method for a wet T-shaped stringer with net dimensions according to claim 1, characterized in that, The L-shaped composite stringer forming device (4) includes: lifting module (8), heating component (9), diaphragm component (10), and vacuum worktable component (11). The lifting module (8) includes two lifting mechanisms fixedly placed on the ground and arranged opposite each other. A heating component (9) is installed between the two lifting mechanisms, and the heating component (9) can move precisely in the vertical direction under the drive of the lifting module (8). The diaphragm component (10) is fixedly arranged on the lower end face of the heating component (9). The vacuum worktable component (11) is placed on the ground and moves to the direct underside of the diaphragm component (10) during operation.

5. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 4, characterized in that, The method of heat insulation film forming in step six by the L-shaped composite stringer forming device (4) is as follows: The L-shaped composite stringer forming device (4) is used to control the lifting module (8) to move downward so that the diaphragm assembly (10) covers the upper surface of the vacuum worktable assembly (11), so that the diaphragm assembly (10) and the vacuum worktable assembly (11) are completely in contact and form a closed space, and seal multiple combined molds and composite material net-size flat blanks (2) fixed on both sides of the upper end of each combined mold in the closed space; by controlling the heating assembly (9) to heat the closed space, and controlling the vacuum worktable assembly (11) to evacuate the closed space, the elastic membrane (13) in the diaphragm assembly (10) deforms and bends the composite material net-size flat blanks (2) to form an L-shaped stringer preform (7) in the L-shaped groove of each combined mold, thereby realizing thermal diaphragm forming.

6. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 4, characterized in that, The diaphragm assembly (10) includes: a fixed frame (12) and an elastic membrane (13); the fixed frame (12) is a hollow spiral structure, and the elastic membrane (13) is a rectangular rubber membrane with a certain elastic modulus. The elastic membrane (13) is fixed to the lower end face of the fixed frame (12).

7. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 4, characterized in that, The vacuum worktable assembly (11) includes: a worktable surface (14), a sealing ring (15), a support frame (16), and a vacuum generator (17); wherein, the worktable surface (14) is configured as a rectangular worktable surface, and the central area is divided into an array of rectangular block structures by multiple through slots opened horizontally and vertically, and a semi-circular cross-section groove is opened around the upper end surface for setting the sealing ring (15) in the groove. The support frame (16) is fixedly installed at the lower part of the workbench (14) to support the workbench (14). Multiple vacuum generators (17) are spaced apart inside the support frame (16). Each vacuum generator (17) is connected to the workbench (14) through an air pipe and is used to draw air from the upper part of the workbench (14) through the through groove of the workbench (14) and discharge it from the bottom of the support frame (16).

8. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 1, characterized in that, The mating assembly (6) includes: a mating table (18) and a servo electric cylinder (19). The upper surface of the mating platform (18) is a plane, and multiple longitudinally arranged servo electric cylinders (19) are arranged parallel to each other along the length direction on the upper surface of the mating platform (18) to provide pressure for the mating of multiple L-shaped stringer prefabricated bodies (7) and combined molds; and a positioning block is provided on one side of the upper surface of the mating platform (18), which serves as the reference surface for the mating and pressing of multiple combined molds.

9. The automatic forming method for a wet-state T-shaped stringer with net dimensions according to claim 1, characterized in that, The thermal insulation film forming process in step six includes: S1, control the heating component (9) in the L-shaped composite stringer forming device (4) to heat at a heating rate of 4℃ / min, heat to 70℃, and keep warm for 10min; S2, control the lifting module (8) to drive the diaphragm assembly (10) to descend at a rate of 1-4 mm / s, cover the upper surface of the vacuum worktable assembly (11), and fit it completely to form a closed space, and multiple combined molds and composite material net-size flat blanks (2) fixed on both sides of the upper end of each combined mold are in this closed space. S3, maintain the preforming temperature, control the vacuum workbench assembly (11) to slowly apply vacuum at a rate of 3 kpa / min until the composite net-size flat blank (2) is completely in contact with the composite core mold (5) on the preforming mold base (3) to form an L-shaped stringer preform (7), and then continue to apply vacuum at 20 kpa / min until the vacuum degree reaches 0.06 MPa, and maintain for 10 min; S4, maintain maximum vacuum, control the heating component (9) to cool down at a rate not greater than 4℃ / min, and cool down to a temperature ≤40℃; S5, control the vacuum stage assembly (11) to unload the vacuum; S6, control the lifting module (8) to drive the diaphragm assembly (10) to move upward, open the closed space, and move the multiple combined molds and the L-shaped stringer prefabricated body (7) formed on both sides of the upper end of each combined mold from the vacuum workbench assembly (11) to the next work station; Among them, the total time from the start of heating to the cooling to room temperature of the composite material net-size flat blank (2) shall not exceed 120 min.

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