A method for suppressing defects in large-area thermal protection bonding of flight products

Abstract

This invention relates to the field of thermal protection systems for high-speed flight products, specifically to a method for suppressing bonding defects in large-area thermal protection systems. The method includes the following steps: S1 cleaning the surface of the flight product; S2 surface treatment of the thermal protection components; S3 surface inspection; S4 temperature difference detection; S5 setting the adhesive thickness reference; S6 applying adhesive; and S7 curing. By suppressing defects in the large-area thermal protection bonding assembly process, this method can achieve improved bonding strength, effective bonding area, surface contour accuracy, and step accuracy in the thermal protection system of flight products, meeting the requirements for high-quality, reusable, and highly reliable bonding assembly of the thermal protection system.

Description

Technical Field

[0001] This invention relates to the field of thermal protection systems for high-speed flight products, and specifically to a method for suppressing large-area thermal protection bonding defects. Background Technology

[0002] Large-area thermal protection bonding assembly refers to an assembly method in which thermal protection components are reliably connected to the surface of the aircraft's load-bearing structure using low-stress, high-damage-tolerance adhesives in areas where the thermal flux gradient changes are small, excluding the leading edge, wing control surfaces, and various interference zones, thereby achieving the aircraft's thermal protection function. Large-area thermal protection bonding assembly is one of the key technical means to ensure the normal operation of the main equipment and the mechanical performance of the load-bearing structure of high-speed flight products.

[0003] However, during the bonding and assembly process of thermal protection components, there are problems such as poor matching between the component and the cabin surface, contamination of the surface of the bonded object with foreign matter such as oil stains, and inaccurate control of curing temperature. These problems can lead to weak bonding, local lack of adhesive or insufficient adhesive application, and uneven adhesive film thickness, ultimately resulting in various bonding defects in the bonding structure of thermal protection components.

[0004] The formation of a stable adhesive interface through the impregnation of adhesives on the surface of large-area thermal protection materials is a crucial prerequisite for ensuring bond strength. Therefore, minimizing defects at the interface of heterogeneous materials is also a key approach to maintaining interfacial bond strength. Summary of the Invention

[0005] This invention proposes a method for suppressing large-area thermal protection bonding defects, which meets the requirements of bonding strength, effective bonding area, surface profile accuracy, and step accuracy of thermal protection systems for high-speed flight products.

[0006] A method for suppressing large-area thermally protected adhesive defects includes the following steps:

[0007] S1 Flight Product Cabin Surface Treatment: Cleaning treatment of the surface of the flight product cabin;

[0008] S2 Thermal Protection Component Surface Treatment: Plasma treatment is performed on the surface of the thermal protection component;

[0009] S3 Surface Inspection: The surface free energy, oil content and roughness of the thermal protection components and the cabin are inspected to meet the preset indicators; if the preset indicators are not met, steps S1 and S2 are repeated.

[0010] S4 Heating Equipment Calibration: A wall temperature sensor is placed on the surface of the flight product cabin. The flight product cabin is placed inside the heating equipment, and the difference between the set temperature of the heating equipment and the actual temperature of the cabin wall surface is recorded. The curing parameters of the heating equipment are adjusted so that the cabin wall surface temperature parameters are consistent with the curing parameters required by the adhesive material for bonding the heat protection components. The curing parameters include heating time, heating rate, and holding time.

[0011] S5 Adhesive Thickness Reference Setting: Pre-fabricated silicone rubber solid film with a width of 9-10mm and a thickness of 0.3-0.8mm is cross-bonded to the surface of the metal chamber as the adhesive thickness reference;

[0012] S6 Apply adhesive: Apply adhesive to make the thickness of the adhesive layer flush with the solid adhesive film that serves as the reference for the adhesive thickness;

[0013] S7 Curing: Bond the heat protection components and cure them according to the curing parameters adjusted in step S4.

[0014] Preferably, in step S1, the surface of the flight product cabin is treated by laser cleaning, with an average laser power of 80-100W, a wavelength of 1062-1066nm, and a movement speed of 200-300mm / s.

[0015] Preferably, in step S2, the surface treatment of the heat protection component is performed using an atmospheric pressure plasma treatment device with an average plasma power of 800-900W, a frequency of 18-20KHz, and a moving speed of 0.3-0.5mm / s.

[0016] Preferably, in step S3, the surface free energy is detected by a dyne pen, the surface oil content is detected by a cleanliness tester, and the surface roughness is detected by a roughness tester.

[0017] Preferably, the preset indicators are: the surface free energy of the thermal protection component and the cabin body is not less than 60mN / m and 50mN / m, respectively; the oil content of the surface of the thermal protection component and the cabin body is less than 5%; and the surface roughness of the thermal protection component and the cabin body is not less than 50μm and 30μm, respectively.

[0018] Preferably, in step S5, the thickness of the adhesive applied to the flat area on the surface of the cabin is measured using a wet film gauge.

[0019] Furthermore, the thickness of the adhesive layer on irregularly shaped parts of the cabin surface is measured using a self-made portable adhesive layer thickness measuring tool; the self-made portable adhesive layer thickness measuring tool is inverted "U" shaped, with a movable measuring ruler in the middle, and the thickness is measured by the height difference between it and the support arms on both sides.

[0020] Preferably, in step S6, when applying adhesive to a layer thickness of 1.0 mm or more, a high-viscosity adhesive is first applied for surface compensation, and the bonding is carried out after initial curing for 24 hours.

[0021] Preferably, S7 curing is performed within 30 minutes after the plasma treatment in step S2.

[0022] Preferably, after the S7 curing is completed, the bonding strength of the thermal protection components of the flight product is tested by pull-out method; the effective bonding area is tested by CT non-destructive testing; the contour is tested by a three-dimensional scanner; and the step difference and gap between the thermal protection components are tested by a portable step difference and gap measuring instrument.

[0023] The beneficial effects achieved by this invention are: by suppressing defects in the large-area thermal protection bonding assembly process, the bonding strength, effective bonding area, surface contour accuracy, and step accuracy of the thermal protection system for flight products are improved, thus meeting the requirements of high-quality, reusable, and highly reliable bonding assembly of the thermal protection system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the metal cabin treatment for the flight product of the present invention.

[0025] Figure 2 This is a schematic diagram of the wall temperature sensor arrangement according to the present invention.

[0026] Figure 3 This is a schematic diagram showing the temperature of the cabin surface wall temperature sensor and the temperature of the heating equipment.

[0027] Figure 4 A schematic diagram for setting the reference thickness for adhesive application.

[0028] Figure 5 This is a schematic diagram of a homemade portable adhesive layer thickness measuring tool.

[0029] Explanation of reference numerals in the attached drawings: 1 is the metal cabin of the flight product; 2 is the segmented thermal protection component; 3 is the portable laser cleaning equipment; 4 is the portable atmospheric pressure plasma treatment equipment; 5 is the dyne pen; 6 is the cleanliness tester; 7 is the roughness measuring instrument; 8 is the wall temperature sensor; 9 is the solid adhesive film. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the following embodiments.

[0031] It should be noted that the present invention is not limited to the following embodiments. Unless otherwise specified, all methods described are conventional methods. Unless otherwise specified, all raw materials are available from publicly available commercial sources.

[0032] Example 1

[0033] As attached Figure 1 As shown, the metal cabin and thermal protection components of the flight product were prepared in place. A laser head focal length limiting fixture was installed on a portable laser cleaning device to treat the surface of the metal cabin. The laser average power was 100W, wavelength 1064nm, movement speed 300mm / s, and the treatment was performed twice. Then, a portable atmospheric pressure plasma treatment device was used to treat the surface of the thermal protection components. The plasma average power was 900W, frequency 20kHz, movement speed 0.5mm / s, and the treatment was performed twice. Bonding was carried out within 30 minutes after plasma treatment.

[0034] After pre-bonding treatment, the surface free energy of the thermal protection component is tested using a dyne pen and is not less than 60 mN / m, and the surface free energy of the metal chamber is not less than 50 mN / m. The oil content on the surface of the thermal protection component and the metal chamber is tested using a cleanliness tester and is less than 5%. The surface roughness of the metal chamber is tested using a roughness tester and is not less than 30 μm, and the surface roughness of the thermal protection component is not less than 50 μm.

[0035] After the surface pretreatment for bonding is completed, as shown in the attached image. Figure 2 As shown, prefabricated silicone rubber solid films with a width of 10mm and a thickness ranging from 0.3 to 0.8mm are plasma-treated and then cross-bonded to the surface of the metal chamber as a reference for adhesive thickness. Spraying and scraping methods are used to ensure the adhesive layer thickness is roughly flush with the solid film. For large areas, a wet film gauge is used to measure the adhesive thickness, while for irregularly shaped areas such as corners and protrusions, a self-made portable adhesive thickness measuring tool is used. A schematic diagram of the self-made portable adhesive thickness measuring tool is shown below. Figure 5 As shown.

[0036] After the heat protection components are bonded, as shown in the attached document. Figure 3 As shown, 3-5 wall temperature sensors are arranged on the surface of the flight product cabin to record the difference between the temperature of the heating equipment oven set according to the curing requirements of the adhesive film material and the actual temperature of the cabin wall surface. Figure 4 As shown. Adjust the adhesive curing parameters (heating time, heating rate, and holding time) to make the actual temperature rise rate and holding time of the bulkhead surface consistent with the temperature rise rate and holding time required for the curing of the adhesive film material.

[0037] After curing, the bonding strength of the thermal protection components of the flight product was tested using the pull-out method to ensure it met the requirements; the effective bonding area was tested using CT non-destructive testing to ensure it met the requirements; the contour was tested using a 3D scanner to ensure it met the requirements; and the step difference and gap between the thermal protection components were tested using a portable step difference and gap measuring instrument to ensure they met the technical requirements.

Claims

1. A method for suppressing large-area thermally protective bonding defects, characterized in that, Specifically, the following steps are included: S1 Flight Product Cabin Surface Treatment: Cleaning treatment of the surface of the flight product cabin; S2 Thermal Protection Component Surface Treatment: Plasma treatment is performed on the surface of the thermal protection component; The plasma treatment operation is as follows: the surface of the heat protection component is treated with an atmospheric pressure plasma treatment device, with an average plasma power of 800~900W, a frequency of 18~20KHz, and a moving speed of 0.3~0.5mm / s; S3 Surface Inspection: The surface free energy, oil content and roughness of the thermal protection components and the cabin are inspected to meet the preset indicators; if the preset indicators are not met, steps S1 and S2 are repeated. The preset indicators are: the free energy of the thermal protection component and the cabin surface is not less than 60mN / m and 50mN / m respectively; the oil content of the thermal protection component and the cabin surface is less than 5%; and the surface roughness of the thermal protection component and the cabin surface is not less than 50μm and 30μm respectively. S4 Heating Equipment Calibration: A wall temperature sensor is placed on the surface of the flight product cabin. The flight product cabin is placed inside the heating equipment, and the difference between the set temperature of the heating equipment and the actual temperature of the cabin wall surface is recorded. The curing parameters of the heating equipment are adjusted so that the cabin wall surface temperature parameters are consistent with the curing parameters required by the adhesive material for bonding the heat protection components. The curing parameters include heating time, heating rate, and holding time. S5 Adhesive Thickness Reference Setting: Pre-fabricated silicone rubber solid film with a width of 9~10mm and a thickness of 0.3~0.8mm is cross-bonded to the surface of the metal chamber as the adhesive thickness reference; S6 Apply adhesive: Apply adhesive to make the thickness of the adhesive layer flush with the solid adhesive film that serves as the reference for the adhesive thickness; S7 Curing: Bond the heat protection components and cure them according to the curing parameters adjusted in step S4.

2. The method for suppressing large-area thermal protection bonding defects according to claim 1, characterized in that, In step S1, the surface of the flight product cabin is treated by laser cleaning, with an average laser power of 80~100W, a wavelength of 1062~1066nm, and a movement speed of 200~300mm / s.

3. The method for suppressing large-area thermal protection bonding defects according to claim 1, characterized in that, In step S3, the surface free energy is detected by a dyne pen, the surface oil content is detected by a cleanliness tester, and the surface roughness is detected by a roughness tester.

4. The method for suppressing large-area thermal protection bonding defects according to claim 1, characterized in that, In step S5, the thickness of the adhesive applied to the flat area on the surface of the cabin is measured using a wet film gauge.

5. The method for suppressing large-area thermal protection bonding defects according to claim 4, characterized in that, The thickness of the adhesive layer on irregularly shaped parts of the cabin surface is measured using a self-made portable adhesive layer thickness measuring tool. The self-made portable adhesive layer thickness measuring tool is inverted "U" shaped, with a movable measuring ruler in the middle, and the thickness is measured by the height difference between it and the support arms on both sides.

6. The method for suppressing large-area thermally protective bonding defects according to claim 1, characterized in that, In step S6, when applying adhesive with a thickness of 1.0 mm or more, a high-viscosity adhesive is first applied for surface compensation, and the bonding is carried out after initial curing for 24 hours.

7. The method for suppressing large-area thermal protection bonding defects according to claim 1, characterized in that, After the plasma treatment is completed in step S2, curing in step S7 shall be carried out within 30 minutes.

8. The method for suppressing large-area thermal protection bonding defects according to claim 1, characterized in that, After the S7 curing is completed, the bonding strength of the thermal protection components of the flight product is tested by the pull-out method. The effective area of ​​the bond was determined by CT non-destructive testing, and the contour was determined by a 3D scanner. A portable step difference and gap measuring instrument was used to detect the step difference and gap between the thermal protection components.

Images