Hollow blade bonding process for a honeycomb sandwich structure

Abstract

The hollow blade bonding process method of the honeycomb sandwich structure of the application comprises the following steps: S1, preforming the honeycomb and removing the surface allowance; S2, film checking; S3, respectively performing phosphoric acid anodizing treatment on the honeycomb, the blade panel and the body to improve the subsequent bonding strength; S4, using an automatic unloading machine to respectively cut the high-temperature curing film according to the plate-plate bonding area and the plate-core bonding area two-dimensional development diagram of the profile contour; and S5, sequentially performing heat treatment on the body on the honeycomb and the blade panel through the high-temperature curing film to form a final blade, thereby improving the processing efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of bonding and processing of hollow blades, and particularly relates to a bonding process method for hollow blades with a honeycomb sandwich structure. Background Technology

[0002] As the bypass ratio of civilian turbofan engines continues to increase, the outer bypass diameter also increases, leading to a corresponding increase in the size and number of fan outlet guide vanes (typically dozens). The heavy weight of these fan outlet guide vanes contributes significantly to the overall weight of the outer bypass. Solid blades are heavy, vibrate excessively, and have poor resistance to foreign object damage, failing to meet the demands for high bypass ratios, high thrust, and low fuel consumption. Reducing the weight of the fan outlet guide vanes would be significantly beneficial for overall engine weight reduction.

[0003] Hollow honeycomb sandwich aluminum / titanium alloy blades are an advanced structural component used in aero engines. They reduce weight through an internal hollow design, while the internal bonded honeycomb structure provides structural strength and rigidity. This design effectively reduces the overall weight of the engine, thereby improving fuel efficiency and overall performance. Existing bonding processes use direct bonding, resulting in low processing efficiency. Summary of the Invention

[0004] The bonding process for hollow blades with honeycomb sandwich structures disclosed in this invention effectively reduces porosity defects at the bonding interface, precisely controls the uniformity of adhesive layer thickness, solves the problem of localized debonding or weak bonding in the bonding area during the bonding process of hollow honeycomb sandwich structure blades, significantly improves the bonding qualification rate, and solves problems such as blade deformation and bonding gaps.

[0005] A bonding process for hollow blades with a honeycomb sandwich structure, the blade comprising a honeycomb structure, a blade facet, and an arc-shaped body, includes the following steps. S1: Pre-form the honeycomb and remove any excess material from the surface; S2: Adhesive film verification. The area where the body is bonded to the blade panel is considered the board-to-board bonding area, and the area where the honeycomb is bonded to the body and blade panel is considered the board-to-core bonding area. The board-core bonding area is first covered with a calibration adhesive film, and then the honeycomb is placed. A spacer is placed between the honeycomb and the body to adjust the honeycomb to the standard orientation position. After adjustment, a calibration film is then laid on the upper surface of the honeycomb. The calibration adhesive film is laid in the plate-to-plate bonding area, and the blade panel is placed there; The assembled blades are wrapped in vacuum bags and then heat-treated. Remove the calibration film and perform calibration; S3: The honeycomb, blade panel and body are respectively subjected to phosphoric acid anodizing treatment to improve the subsequent bonding strength; S4: Use an automatic cutting machine to cut the high-temperature curing adhesive film according to the two-dimensional unfolded diagram of the surface contour of the board-to-board bonding area and the board-to-core bonding area respectively; S5: The honeycomb and blade panels are heat-treated sequentially on the body through the high-temperature curing adhesive film to form the final blade.

[0006] The beneficial effects of the present invention are as follows: By increasing the allowance during honeycomb preforming and then removing honeycomb wall collapse and wrinkles during molding through machining, the pass rate of honeycomb mating surfaces is improved. The hollow blade body, honeycomb, and panel are bonded using an autoclave transfer process and tooling. This allows for simultaneous mass production and curing, resulting in low cost, high bond pass rate, low bonding interface porosity defects, precise control of adhesive layer thickness uniformity, and a significant improvement in the peel strength, pre-shear strength, and fatigue strength of the bonded structure. Attached Figure Description To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0007] Figure 1 A top view showing the two bonding areas; Figure 2 A schematic diagram showing the installation of the gasket; Figure 3 For along Figure 2 A cross-sectional view along the width direction; Figure 4 This is a schematic diagram of vacuum bag packaging; Figure 5 This is a top view of the deformation control fixture; Figure 6 This is an AA sectional view of the deformation control fixture. Detailed Implementation

[0008] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0009] The following specific examples illustrate the implementation of this disclosure. Those skilled in the art can easily understand other advantages and effects of this disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. This disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this disclosure. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0010] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this disclosure, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using other structures and / or functionalities besides one or more of the aspects set forth herein.

[0011] like Figures 1 to 6 The method for bonding hollow blades with a honeycomb sandwich structure, as shown, is used for hollow blades, which are mostly aluminum alloy blades. The blade includes a honeycomb structure, a blade panel, and a curved body structure. The method includes the following steps. S1: Pre-form the honeycomb and remove the surface excess. Specifically, the blade honeycomb requires the normal to be perpendicular to the body cavity surface, so the honeycomb adopts a pre-forming process. Due to the large curvature of the part surface, the honeycomb wall will wrinkle and collapse during the honeycomb pre-forming process. A machining fixture is used to mill off 1mm of the excess on the upper surface of the honeycomb to eliminate the impact of local debonding / weak bonding in the honeycomb area caused by the wrinkles and collapse of the honeycomb wall during the honeycomb pre-forming process. S2: Adhesive film verification. The area where the body is bonded to the blade panel is designated as the board-to-board bonding area, and the bonding area between the honeycomb and the body / blade panel is designated as the board-to-core bonding area. (The body has an arc-shaped structure with grooves; therefore, the board-to-board bonding area is above the board-to-core bonding area.) First, lay the calibration adhesive film (0.3mm thick) in the board-core bonding area, and then place the honeycomb. Spacers are placed between the honeycomb and the body to adjust the honeycomb to the standard position. After adjustment, a calibration film is then laid on the upper surface of the honeycomb. The calibration adhesive film is laid in the board-to-board bonding area, and the blade panel is placed there; The assembled blades are wrapped in vacuum bags and then heat-treated. For example, the assembled blades are made in vacuum bags and placed in an autoclave for heating and pressurization to simulate the pressure in the final solidification state. The heat preservation temperature is 70℃±5℃, the pressure is 300KPa±10KPa, and the heat preservation time is 45min±15min. Remove the calibration film and perform calibration. Specifically, If the honeycomb wall indentations on the surface of the cavity are clear and uniform (bottom surface of the groove), no repair is needed. Conversely, if the indentations are missing, the honeycomb structure is unusable.

[0012] The panel bonding area is divided into the board-to-board bonding area and the board-to-core bonding area. The fit of the board-to-core area will affect the fit of the board-to-board area. If the honeycomb wall inspection film imprint in the board-to-core area is uniform, clear, and without defects, and the inspection film indentation in the board-to-board area is uniform, clear, and without defects, then the honeycomb and blade panels are qualified.

[0013] If the verification film at the junction of the honeycomb and the board area is thick or has no indentation, it indicates that the honeycomb height is higher than the bonding surface of the blade body. It is necessary to measure the excess value, mill the honeycomb to remove the excess, and then re-verify.

[0014] If there are gaps or missing indentations in the calibration film on the outer side of the panel area, the edge of the panel in that area needs to be repaired to ensure that the gap between the blade panel and the body is controlled within 0.4-0.6mm. After repair, re-calibrate.

[0015] S3: The honeycomb, blade panel and body are respectively subjected to phosphoric acid anodizing treatment to improve the subsequent bonding strength; S4: Use an automatic cutting machine to cut the high-temperature curing adhesive film according to the two-dimensional unfolded diagram of the surface contour of the board-to-board bonding area and the board-to-core bonding area respectively; S5: The honeycomb and blade panels are heat-treated sequentially on the body using a high-temperature curing adhesive film to form the final blade. Specifically... The honeycomb structure involves heat treatment on the substrate via high-temperature curing of the adhesive film, including... A high-temperature curing adhesive film is laid in the board-core bonding area, and honeycomb is placed there; Space the pads at intervals (within 2mm) to control the gap between the honeycomb and the inner edge of the body, adjust the honeycomb to the standard position, and fix it with a vacuum bag; The honeycomb and the blade body are bonded together by a curing film in a vacuum oven. The parameters of the vacuum oven are: temperature 80℃±5℃, pressure -90Kpa, and holding time 45min±15min. The relative positions are fixed so that the honeycomb position will not be moved during subsequent operations. Remove the circumferential pads from the honeycomb. There is a 1.5-2.0mm gap between the honeycomb's side surfaces and the main body. Use a glue gun to inject filler glue into the gap between the honeycomb and the blade body to reinforce the honeycomb. A high-temperature curing adhesive film is laid on the honeycomb surface. The parameters of the hot air gun are adjusted to 80-100℃ to provide auxiliary heating to the adhesive film, thereby improving its adhesion and ensuring that there are no bubbles or wrinkles in the adhesive film bonding area.

[0016] The blade panel undergoes heat treatment on the body via a high-temperature curing adhesive film, including... After the honeycomb and the body are thermoformed, a high-temperature curing adhesive film is laid in the board-to-board bonding area and fixed and limited by high-temperature tape; The integral blade is placed on a deformation control fixture and fitted with a high-temperature resistant vacuum bag; The adhesive is cured by placing it in an autoclave, where the autoclave is kept at a temperature of 170℃±5℃ and a pressure of 300KPa±10Kpa.

[0017] Furthermore, the deformation control fixture includes a base 1 and a limiting block 2 (to limit the deformation of the blade profile caused by residual stress during bonding at high temperatures), wherein, The base has an arc groove in the center of the top surface for placing the main body. A first protective box 3 and a second protective box 4 are respectively provided on the top surface of the base and on both sides of the arc groove. The first protective box and the second protective box are used to accommodate the large and small tenons on both sides of the blade. The second protective box 4 and the first protective box 3 are hollow structures, and the bottom surface is adapted to the shape of the tenon or the tenon is suspended. The second protective box 4 is larger than the first protective box 3, and a limiting seat in the prior art is provided on the inner bottom surface of the second protective box 4 to prevent the tenon from shaking.

[0018] Multiple limiting blocks are spaced apart along the width of the base and contact the body to prevent thermal deformation of the body.

[0019] By controlling the blade body area (body) with constraint tooling, the problem of large deformation after high-temperature curing of the blade is solved, and the problem of vacuum bags easily bursting in the complex area of ​​the blade tenon cavity is solved, ensuring the bonding quality of the entire blade panel and the blade body.

[0020] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A bonding process for hollow blades with a honeycomb sandwich structure, the blade comprising a honeycomb structure, a blade panel, and an arc-shaped body, characterized in that, Includes the following steps, S1: Pre-form the honeycomb and remove any excess material from the surface; S2: Adhesive film verification. The area where the body is bonded to the blade panel is considered the board-to-board bonding area, and the area where the honeycomb is bonded to the body and blade panel is considered the board-to-core bonding area. The board-core bonding area is first covered with a calibration adhesive film, and then the honeycomb is placed. A spacer is placed between the honeycomb and the body to adjust the honeycomb to the standard orientation position. After adjustment, a calibration film is then laid on the upper surface of the honeycomb. The calibration adhesive film is laid in the plate-to-plate bonding area, and the blade panel is placed there; The assembled blades are wrapped in vacuum bags and then heat-treated. Remove the calibration film and perform calibration; S3: The honeycomb, blade panel and body are respectively subjected to phosphoric acid anodizing treatment to improve the subsequent bonding strength; S4: Use an automatic cutting machine to cut the high-temperature curing adhesive film according to the two-dimensional unfolded diagram of the surface contour of the board-to-board bonding area and the board-to-core bonding area respectively; S5: The honeycomb and blade panels are heat-treated sequentially on the body through the high-temperature curing adhesive film to form the final blade.

2. The method according to claim 1, characterized in that, S2 involves vacuum-packing the assembled blades and then subjecting them to heat treatment. The assembled blades are wrapped in vacuum bags and placed in an autoclave for heating and pressurization to simulate the pressure in the final curing state. The heat preservation temperature is 70℃±5℃, the pressure is 300KPa±10KPa, and the heat preservation time is 45min±15min.

3. The method according to claim 1, characterized in that, S2 includes removing the calibration film and performing calibration, including... If the honeycomb wall indentation on the surface of the body cavity is clear and uniform, no repair is needed; otherwise, if the indentation is missing, the honeycomb should be replaced and re-verified. or If the inspection adhesive film imprints in the board-core bonding area and the board-board bonding area are uniform, clear and without omissions, then the honeycomb and blade panels are qualified. or If the verification film at the junction of the honeycomb and the plate-to-plate adhesive area is thick or has no indentation, it indicates that the honeycomb height is higher than the bonding surface of the blade body. Measure the excess value and mill the honeycomb to remove the excess, then re-verify; or If there are gaps in the calibration film on the outer side of the plate-to-plate bonding area, or if there are missing indentations in some areas, the edge of the panel in that area needs to be repaired to ensure that the gap between the blade panel and the body is controlled within 0.4-0.6mm. After the repair is completed, the calibration is carried out again.

4. The method according to claim 1, characterized in that, In S5, the honeycomb structure undergoes heat treatment on the body via the high-temperature cured adhesive film. The high-temperature curing adhesive film is laid in the board-core bonding area, and honeycomb is placed there; Spacers are placed at intervals to control the gap between the honeycomb and the inner edge of the body. The honeycomb is adjusted to the standard position and fixed with a vacuum bag. The honeycomb and the blade body are bonded together by a curing film in a vacuum oven. The parameters of the vacuum oven are: temperature 80℃±5℃, pressure -90Kpa, and holding time 45min±15min. Remove the circumferential gaskets from the honeycomb and use a glue gun to inject filler glue into the gap between the honeycomb and the blade body to reinforce the honeycomb. The high-temperature curing adhesive film is laid on the honeycomb surface, and the parameters of the hot air gun are adjusted to 80-100℃ to provide auxiliary heating for the adhesive film.

5. The method according to claim 4, characterized in that, The blade panel in S5 undergoes heat treatment on the body via the high-temperature curing adhesive film. After the honeycomb and the body are thermoformed, the high-temperature curing adhesive film is laid in the board-to-board bonding area and fixed and limited by high-temperature tape. The integral blade is placed on a deformation control fixture and fitted with a high-temperature resistant vacuum bag; The adhesive is cured by placing it in an autoclave, where the autoclave is kept at a temperature of 170℃±5℃ and a pressure of 300KPa±10Kpa.

6. The method according to claim 5, characterized in that, The controlled deformation fixture includes a base and a limiting block, wherein... The base has an arc groove in the center of its top surface for placing the main body. A first protective box and a second protective box are respectively provided on the top surface of the base and on both sides of the arc groove. The first protective box and the second protective box are respectively used to accommodate the large and small tenons on both sides of the blade. Multiple limiting blocks are spaced apart along the width direction of the base and contact the body to prevent thermal deformation of the body.

Images