Repairing and polishing method for composite material laminated structure

Abstract

The invention relates to the technical field of aeronautical manufacturing, and particularly discloses a repairing and polishing method for a composite laminated structure. According to the number of grinding layers, a preset slope and the thickness of each layer, the outward expansion width of the coarse grinding area of each layer relative to the positioning grinding area is determined, a coarse grinding step face is ground, then the outward expansion width of the fine grinding area of each layer relative to the coarse grinding area is determined, and finally a lap joint inclined face is obtained after grinding. The lapping width of each layer is guaranteed to meet the requirement, meanwhile, the lapping slope after polishing is flat and smooth, the skill requirement for repairing operators is lowered, the polishing time is shortened, and the efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of aerospace manufacturing technology, and in particular to a method for repairing and polishing composite laminate structures. Background Technology

[0002] Repairing composite laminate structures involves minimal changes to the part's shape and offers a relatively higher strength recovery rate, making it widely used for repairing structural damage to aircraft surfaces with aerodynamic requirements. During the repair process, the composite laminate structure must first be ground to create an overlapping bevel. The size and precision of this bevel directly determine the level of structural strength recovery after repair.

[0003] Laser polishing is often used in related technologies to ensure high polishing precision. However, laser polishing requires transporting the damaged composite laminate parts to the laser equipment. In practice, most composite laminate parts cannot be transported to laser equipment and must be polished on-site using manual polishing tools. During manual polishing, the plywood in the damaged area is first removed based on the size and depth of the damage. Then, multiple bevel polishing operations are performed until the final bevel meets the specified slope requirements. This process requires real-time measurement of the overlap width of each layer, and the finished bevel surface must be smooth and flat. This demands a high level of skill from the repair operators and is time-consuming and inefficient. Summary of the Invention

[0004] The purpose of this invention is to provide a method for repairing and polishing composite laminate structures, so as to reduce the skill requirements of manual polishing operations and improve polishing efficiency.

[0005] This invention provides a method for repairing and polishing composite laminate structures, using a manual polishing tool. The method includes: S1. Positioning and Grinding: Determine the positioning and grinding area based on the damaged area, and determine the number of grinding layers based on the damage depth. After grinding, a surface without damage is obtained. S2. Rough Grinding: Determine the width of the rough grinding area of ​​each layer relative to the positioning grinding area based on the number of grinding layers, the preset slope and the thickness of each layer. After grinding layer by layer, multiple rough grinding step surfaces are obtained. S3. Fine grinding: Based on the number of grinding layers, the preset slope, and the thickness of each layer, determine the width of the fine grinding area of ​​each layer relative to the coarse grinding area, and obtain an overlapping slope after grinding.

[0006] As a preferred technical solution for the repair and polishing method of composite laminate structures, step S1 includes: S11. Determine the positioning and polishing area based on the damaged area, so that the damaged area completely falls within the positioning and polishing area; S12. Polish layer by layer until the damage disappears. The number of the layer where the damage disappears is the number of polishing layers. S13. Continue polishing until the boundary between the damaged layer and the next layer, to obtain a damage-free surface.

[0007] As a preferred technical solution for the repair and polishing method of composite laminate structures, step S2 includes: S21. From the layer above the damage disappearance layer to the first layer, determine the outer width of the coarse polishing area of ​​each layer relative to the positioning polishing area; S22. Roughly polish layer by layer from the first layer down to the layer above the layer where the damage has disappeared.

[0008] As a preferred technical solution for the repair and polishing method of composite laminate structures, determining the outward expansion width of the coarse polishing area relative to the positioning polishing area includes: Let the preset slope be k, let the number of the layer where the damage disappears be n, and let the thickness of the a-th layer be M. a Let W be the outward expansion width of the coarse polishing area of ​​layer a relative to the positioning polishing area. a Then W a =W a+1 +M a / k, and a<n.

[0009] As a preferred technical solution for repairing and polishing composite laminate structures, pressure-sensitive adhesive tape is pasted on the outer side of the edge of the rough polishing area of ​​the first layer.

[0010] As a preferred technical solution for repairing and polishing composite laminate structures, the polishing depth of each layer is equal to the thickness of that layer.

[0011] As a preferred technical solution for the repair and polishing method of composite laminate structures, step S3 includes: S31. Determine the outer width of the fine polishing area of ​​the first layer relative to the coarse polishing area of ​​the first layer; S32. Polish along the edge of the undamaged surface layer by layer to the outer edge of the first layer of fine polishing area.

[0012] As a preferred technical solution for repairing and polishing composite laminate structures, pressure-sensitive adhesive tape is pasted on the outer side of the edge of the fine polishing area of ​​the first layer.

[0013] As a preferred technical solution for the repair and polishing method of composite laminate structures, step S32 includes: S321. Divide the fine polishing area into multiple segments connected end to end along the circumference of the undamaged surface. S322. The abrasive moves outward along a direction parallel to the overlapping inclined surface and grinds the multiple fine grinding areas in sequence.

[0014] As a preferred technical solution for the repair and polishing method of composite laminate structures, the abrasive particle size of the manual polishing tool includes 80 mesh to 400 mesh.

[0015] The beneficial effects of this invention are as follows: This invention provides a method for repairing and grinding composite laminate structures. During the grinding process using manual grinding tools, after determining the number of grinding layers, the width of the coarse grinding area of ​​each layer relative to the positioning grinding area is determined based on the number of grinding layers, the preset slope, and the thickness of each layer. This creates a coarse grinding step surface. Then, the width of the fine grinding area of ​​each layer relative to the coarse grinding area is determined. Finally, an overlapping slope is obtained after grinding. This method ensures that the overlap width of each layer meets the requirements, while also producing a smooth and flat overlapping slope after grinding. It reduces the skill requirements for repair operators, shortens grinding time, and improves efficiency. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of damage to the composite laminate structure in an embodiment of the present invention; Figure 2 This is a schematic diagram of the damaged area after positioning and grinding in an embodiment of the present invention; Figure 3 This is a schematic diagram of the rough grinding of the first layer of the composite laminate structure in an embodiment of the present invention; Figure 4 This is a schematic diagram of the outline of the rough grinding of the first layer of the composite laminate structure in an embodiment of the present invention; Figure 5 This is a schematic diagram showing the result after rough polishing in an embodiment of the present invention; Figure 6 This is a schematic diagram of the outline after rough grinding in an embodiment of the present invention; Figure 7 This is a schematic diagram of the path for fine grinding of the composite laminate structure in an embodiment of the present invention; Figure 8 This is a schematic diagram of the boundaries of each layer of the composite laminate structure after fine grinding in an embodiment of the present invention; Figure 9 This is a schematic diagram showing the result after fine polishing in an embodiment of the present invention.

[0017] In the picture: 100. Multilayer composite laminate structure parts; 200. Damaged area; 1. Define the polishing area; 11. Ensure a undamaged surface; 2. Rough grinding area; 21. Rough grinding of the step surface; 3. Fine-polished area; 31. Overlapping bevel. Detailed Implementation

[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Furthermore, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0021] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0022] like Figures 1-9As shown, this invention provides a method for repairing and grinding composite laminate structures, applied to the grinding process in the repair of damaged composite laminate structures. Specifically, grinding is performed using a manual grinding tool, which can be a pneumatic grinder, an electric grinder, or a grinding wheel, etc., and can be flexibly selected according to actual grinding needs; no specific limitation is made here. Specifically, the method for repairing and grinding composite laminate structures includes: S1. Positioning and grinding: Determine the positioning and grinding area 1 based on the damaged area 200, and determine the number of grinding layers based on the damage depth. After grinding, a surface 11 without damage is obtained. S2. Rough grinding: Determine the width of the rough grinding area 2 of each layer relative to the positioning grinding area 1 based on the number of grinding layers, the preset slope and the thickness of each layer. After grinding layer by layer, multiple rough grinding step surfaces 21 are obtained. S3. Fine grinding: Determine the width of the fine grinding area 3 of each layer relative to the coarse grinding area 2 based on the number of grinding layers, the preset slope and the thickness of each layer. After grinding, an overlapping slope 31 is obtained.

[0023] During the initial grinding, the shape of the initial grinding area 1 is determined based on the shape of the damage in the damaged area 200, ensuring that the initial grinding area 1 completely covers the damaged area 200. Grinding is then performed layer by layer downwards until the damage disappears, determining the number of grinding layers and obtaining a undamaged surface 11. The shape of the undamaged surface 11 is consistent with the shape of the initial grinding area 1. During rough grinding, the width of each rough grinding area 2 relative to the initial grinding area 1 is determined based on the number of grinding layers, the preset slope, and the thickness of each layer. After grinding layer by layer, multiple step structures and corresponding rough grinding step surfaces 21 are obtained. The rough grinding step surface 21 located inside the outer step structure is the adjacent rough grinding step surface 21 located outside the inner step structure, meaning the multiple step structures after rough grinding are connected end to end. During fine grinding, the width of each fine grinding area 3 relative to the rough grinding area 2 is determined based on the number of grinding layers, the preset slope, and the thickness of each layer. The multiple step structures after rough grinding are then ground to obtain a compliant overlapping slope surface 31. By applying the composite material laminate structure repair and polishing method in this embodiment, during the polishing process using manual polishing tools, after determining the number of polishing layers, the width of the coarse polishing area 2 of each layer relative to the positioning polishing area 1 is determined according to the number of polishing layers, the preset slope, and the thickness of each layer, thus polishing out the coarse polishing step surface 21. Then, the width of the fine polishing area 3 of each layer relative to the coarse polishing area 2 is determined, and finally, an overlapping slope 31 is obtained after polishing. While ensuring that the overlapping width of each layer meets the requirements, the overlapping slope 31 after polishing is flat and smooth, reducing the skill requirements of the repair operator, shortening the polishing time, and improving efficiency.

[0024] Furthermore, such as Figures 1-2 As shown, step S1 includes: S11. Determine the positioning and grinding area 1 based on the damaged area 200, so that the damaged area 200 completely falls into the positioning and grinding area 1. S12. Polish layer by layer until the damage disappears. The number of the layer where the damage disappears is the number of polishing layers. S13. Continue polishing until the boundary between the damaged layer and the next layer, to obtain a damage-free surface 11.

[0025] When positioning and grinding area 1 is ground to a certain layer, if the grinding depth exceeds the damage depth, the damage disappears. This layer is called the damage disappearance layer, and the number of damage disappearance layers is the number of grinding layers. Grinding continues until the boundary between the damage disappearance layer and the next layer, resulting in a damage-free surface 11. This step ensures that the damage is completely eliminated and facilitates the overlapping of repair materials, thus guaranteeing the repair effect of the composite laminate structure.

[0026] Furthermore, such as Figures 3-6 As shown, step S2 includes: S21. From the layer above the damage disappearance layer to the first layer, determine the outer width of the coarse grinding area 2 relative to the positioning grinding area 1 of each layer. S22. Roughly polish layer by layer from the first layer down to the layer above the layer where the damage has disappeared.

[0027] During rough polishing, the outer width of the rough polishing area 2 located on the outside is greater than the outer width of the adjacent inner rough polishing area 2. Therefore, the outer width of the rough polishing area 2 above the damage disappearance layer relative to the positioning polishing area 1 is first determined. Then, the outer width of the rough polishing area 2 relative to the positioning polishing area 1 is determined layer by layer from the layer above the damage disappearance layer to the first layer. The rough polishing is then carried out layer by layer from the first layer down to the layer above the damage disappearance layer to obtain a stepped structure with the ends connected.

[0028] Specifically, determining the outward expansion width of a certain coarse polishing area 2 relative to the positioning polishing area 1 includes: Let the preset slope be k, let the number of the layer where the damage disappears be n, and let the thickness of the a-th layer be M. a Let W be the outer width of the coarse polishing area 2 of layer a relative to the positioning polishing area 1. a Then W a =W a+1 +M a / k, and a<n, where the value of k is determined according to the actual project, for example, the range of k is 1:40-1:20, and no specific limit is made here.

[0029] Taking the fourth layer as the damage disappearance layer in this embodiment as an example, i.e., n is 4, then the outward expansion width W3 of the third layer coarse grinding area 2 relative to the positioning grinding area 1 is W3 = W4 + M3 / k. Since the fourth layer is the damage disappearance layer, no further coarse grinding is needed after positioning grinding, i.e., W4 = 0, therefore W3 = M3 / k; the outward expansion width W2 of the second layer coarse grinding area 2 relative to the positioning grinding area 1 is W2 = W3 + M2 / k, i.e., W2 = M3 / k + M2 / k; the outward expansion width W1 of the first layer coarse grinding area 2 relative to the positioning grinding area 1 is W1 = W2 + M1 / k, i.e., W1 = M3 / k + M2 / k + M1 / k. For the case where the thickness of each layer is equal, let the thickness of each layer be M, then W a = (na)M / k. It should be noted that the outer edge shape of each coarse grinding area 2 depends on the shape of the positioning grinding area 1. The distance from the outer edge of each coarse grinding area 2 to the outer edge of the positioning grinding area 1 is the outer width of that coarse grinding area 2 relative to the positioning grinding area 1. In this embodiment, the positioning grinding area 1 is circular, and correspondingly, the outer edge shape of each coarse grinding area 2 is circular. The difference between its radius and the radius of the positioning grinding area 1 is the outer width of that coarse grinding area 2 relative to the positioning grinding area 1. In other embodiments, the shape of the positioning grinding area 1 can also be set to an ellipse, semicircle, racetrack shape, or oval shape, etc., depending on the shape of the damaged area 200, which will not be described in detail here.

[0030] Optionally, before rough sanding the first layer, pressure-sensitive adhesive tape is applied to the outer edge of the rough sanding area 2 of the first layer to protect the surface of the composite laminate structure and prevent damage to the outer surface of the composite laminate structure during the rough sanding process of the first layer.

[0031] Specifically, during the rough grinding process, the grinding depth of each layer is equal to the thickness of that layer, so as to ensure that the stepped structures of adjacent layers are connected end to end after the rough grinding is completed, and to reserve processing allowance for subsequent fine grinding, so as to ensure that the overlapping slope 31 after fine grinding is flat.

[0032] Furthermore, such as Figures 7-9 As shown, step S3 includes: S31. Determine the outer width of the fine polishing area 3 of the first layer relative to the coarse polishing area 2 of the first layer. S32. Polish layer by layer along the edge of the undamaged surface 11 to the outer edge of the first fine polishing area 3.

[0033] During fine polishing, based on the outward expansion width W1 of the first coarse polishing area 2 relative to the positioning polishing area 1, the outward expansion width W1 of the first fine polishing area 3 relative to the first coarse polishing area 2 is determined according to the thickness M1 of the first layer and the preset slope k. ’=M1 / k. Grind layer by layer along the edge of the undamaged surface 11 to the outer edge of the first fine grinding area 3. During this process, the stepped structure after the coarse grinding is completed is ground to obtain the inclined structure with the beginning and end connected, which is the overlapping inclined surface 31.

[0034] Optionally, before fine sanding, pressure-sensitive tape is applied to the outer edge of the fine sanding area 3 of the first layer to protect the surface of the composite laminate structure and prevent damage to the outer surface of the composite laminate structure during fine sanding.

[0035] Specifically, step S32 includes: S321. Along the circumferential direction of the outer edge of the undamaged surface 11, divide the fine polishing area 3 into multiple segments connected end to end; S322, the abrasive moves outward along a direction parallel to the overlapping inclined surface 31, and grinds the multiple fine grinding areas 3 in sequence.

[0036] After determining the outward expansion width of the first fine grinding area 3 relative to the first coarse grinding area 2, the edge of the first fine grinding area 3 is then determined. At this point, the fine grinding area 3 is divided into multiple segments connected end to end along the circumference of the outer edge of the undamaged surface 11, and these segments are ground sequentially. The abrasive is moved outward parallel to the direction of the overlapping inclined surface 31, ultimately resulting in a smooth and flat overlapping inclined surface 31. To balance the quality of the overlapping inclined surface 31 and the grinding efficiency, multiple fine grinding operations can be performed, with each fine grinding operation using a smaller abrasive particle size compared to the previous one.

[0037] Optionally, the abrasive grit size of the manual polishing tool in this embodiment includes 80-400 mesh. For coarse polishing, relatively coarse grit such as 80 or 160 mesh is preferred. For fine polishing, 240, 320, or 400 mesh abrasive can be used, or, depending on the requirements, 240 mesh abrasive can be used first, followed by a higher grit of 320 or 400 mesh. Specific selection methods are not detailed here.

[0038] The following will be an example of a composite laminate structure where the damage disappearance layer is located in the fourth layer, and each layer has a thickness of 0.188 mm and a preset slope of 1:30. The rough and fine grinding processes are as follows: Determine the outer width of the rough grinding area 2 relative to the positioning grinding area 1 layer by layer: The outer width of the first rough grinding area 2 relative to the positioning grinding area 1 is 3×0.188×30=16.92mm; The outer width of the second rough polishing area 2 relative to the positioning polishing area 1 is 2×0.188×30=11.28mm; The outer width of the third rough polishing area 2 relative to the positioning polishing area 1 is 1×0.188×30=5.64mm; Next, pressure-sensitive adhesive tape is applied to the outside of the first rough sanding area 2 for isolation and protection. Then, based on the outward expansion width of the first rough sanding area 2 relative to the positioning sanding area 1, a sanding tool is used to rough sand the first layer. Then, based on the outward expansion width of the second rough sanding area 2 relative to the positioning sanding area 1, a sanding tool is used to rough sand the second layer. Finally, based on the outward expansion width of the third rough sanding area 2 relative to the positioning sanding area 1, a sanding tool is used to rough sand the third layer.

[0039] The outer width of the first fine grinding area 3 relative to the first coarse grinding area 2 is determined to be 0.188 × 30 = 5.64 mm. The pressure-sensitive tape adhered to the outside of the first coarse grinding area 2 is removed, and pressure-sensitive tape is then adhered to the outside of the first fine grinding area 3 for continued isolation and protection. Multiple grinding operations are performed from the edge of the positioning grinding area 1 to the edge of the first fine grinding area 3, ensuring that the abrasive movement trajectory is approximately parallel in each grinding operation. After the final grinding operation, a satisfactory overlapping bevel 31 is obtained. Practical verification shows that, compared to traditional manual grinding methods, the composite material laminate structure repair grinding method used by the same group of grinding operators significantly increases the pass rate of the overlapping bevel 31 and reduces the grinding time of the overlapping bevel 31 by more than 50%.

[0040] The above description is merely a preferred embodiment of the present invention and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this invention is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-disclosed concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this invention.

[0041] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for repairing and polishing composite laminate structures, characterized in that, The method for repairing and polishing the composite laminate structure using manual polishing tools includes: S1. Positioning and grinding: Determine the positioning and grinding area (1) based on the damaged area (200), determine the number of grinding layers based on the damage depth, and obtain a surface without damage (11) after grinding. S2, rough grinding: Determine the width of the rough grinding area (2) of each layer relative to the positioning grinding area (1) according to the number of grinding layers, the preset slope and the thickness of each layer. After grinding layer by layer, multiple rough grinding step surfaces (21) are obtained. S3. Fine polishing: Based on the number of polishing layers, the preset slope and the thickness of each layer, determine the width of the fine polishing area (3) of each layer that expands outward relative to the coarse polishing area (2), and obtain the overlapping slope (31) after polishing.

2. The method for repairing and polishing composite laminate structures according to claim 1, characterized in that, Step S1 includes: S11. Determine the positioning and polishing area (1) based on the damaged area (200) so that the damaged area (200) falls completely into the positioning and polishing area (1); S12. Polish layer by layer until the damage disappears. The number of the layer where the damage disappears is the number of polishing layers. S13. Continue polishing until the boundary between the damaged layer and the next layer is reached, to obtain a damaged surface (11).

3. The method for repairing and polishing composite laminate structures according to claim 1, characterized in that, Step S2 includes: S21. From the layer above the damage disappearance layer to the first layer, determine the outer width of the coarse polishing area (2) of each layer relative to the positioning polishing area (1); S22. Roughly polish layer by layer from the first layer down to the layer above the layer where the damage has disappeared.

4. The method for repairing and polishing composite laminate structures according to claim 3, characterized in that, Determining the outward expansion width of the rough grinding area (2) relative to the positioning grinding area (1) includes: Let the preset slope be k, let the number of the layer where the damage disappears be n, and let the thickness of the a-th layer be M. a Let W be the outer width of the coarse polishing area (2) of layer a relative to the positioning polishing area (1). a Then W a =W a+1 +M a / k, and a<n.

5. The method for repairing and polishing composite laminate structures according to claim 4, characterized in that, Apply pressure-sensitive tape to the outer edge of the rough sanding area (2) of the first layer.

6. The method for repairing and polishing composite laminate structures according to claim 3, characterized in that, The polishing depth of each layer is equal to the thickness of that layer.

7. The method for repairing and polishing composite laminate structures according to claim 1, characterized in that, Step S3 includes: S31. Determine the outer width of the fine polishing area (3) of the first layer relative to the coarse polishing area (2) of the first layer; S32. Polish along the edge of the undamaged surface (11) layer by layer to the outer edge of the first fine polishing area (3).

8. The method for repairing and polishing composite laminate structures according to claim 7, characterized in that, Apply pressure-sensitive tape to the outer edge of the finely polished area (3) of the first layer.

9. The method for repairing and polishing composite laminate structures according to claim 7, characterized in that, Step S32 includes: S321. Along the circumference of the undamaged surface (11), the fine polishing area (3) is divided into multiple segments connected end to end; S322, the abrasive moves outward along a direction parallel to the overlapping inclined surface (31) and grinds the multiple fine grinding areas (3) in sequence.

10. The method for repairing and polishing composite laminate structures according to any one of claims 1-9, characterized in that, The abrasive grit size of the manual polishing tool includes 80 mesh to 400 mesh.

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