Process for improving the strength of a front edge bonded iron

Abstract

The application discloses a process for improving the bonding strength of a front edge iron wrapping, which comprises the following steps: spraying a primer on the inner surface of the front edge iron wrapping; bonding the front edge iron wrapping to the front edge part of a tail rotor blade of a helicopter; pasting a layer of adhesive film on the primer, cutting off part of the adhesive film at the end position of the front edge iron wrapping close to the root part of the tail rotor blade, and the area corresponding to the cut-off part of the adhesive film is a tinning area of the iron sheet; reserving a certain width of the adhesive film on the outer circumferential side of the tinning area of the iron sheet; applying conductive adhesive on the tinning area of the iron sheet, the conductive adhesive being in contact with the primer, and the iron sheet is fixedly bonded to the conductive adhesive; after the tail rotor blade is processed into a bushing bored hole state, the resistance value between the tip of the front edge iron wrapping and the front edge bushing is measured, the resistance value needs to satisfy R<=1Ω, if the resistance value does not meet the requirement, the gap between the iron sheet and the root bushing is filled and repaired by using epoxy conductive adhesive, and the resistance value is measured again, so as to avoid the problem of the front edge iron wrapping opening.

Description

Technical Field

[0001] This invention relates to the field of adhesive bonding technology for the leading edge of helicopter tail rotor blades, specifically to a process for improving the adhesive bonding strength of the leading edge. Background Technology

[0002] Since the existing tail rotor blades were delivered for field use, there have been multiple instances of partial delamination of the leading edge cladding. Upon inspection of the suspected delamination area of ​​the leading edge cladding, it was found that there was a hollow sound within a 150mm long x 30mm wide area where the leading edge cladding met the polyurethane protective strip, indicating delamination and missing adhesive.

[0003] Therefore, how to provide a process to improve the bonding strength of the leading edge of the iron-clad frame is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a process for improving the bonding strength of the leading edge cladding, which can avoid the phenomenon of delamination of the cladding at the leading edge of the tail rotor blade.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a process for improving the bonding strength of the leading edge of the iron sheath, comprising the following steps:

[0006] Step 1: First, spray primer onto the inner surface of the leading edge cladding; then directly bond the leading edge cladding to the leading edge of the tail rotor blade.

[0007] Step 2: Apply a layer of adhesive film on top of the base adhesive. The adhesive film is used to fix and bond the leading edge cladding to the tail rotor blade. Cut off part of the adhesive film at the end of the leading edge cladding near the root of the tail rotor blade, and the area where the adhesive film is cut off is the tin-plated area of ​​the grounding plate.

[0008] Step 3: Leave a certain width of adhesive film on the outer periphery of the tin-plated area of ​​the grounding sheet;

[0009] Step 4: Apply conductive adhesive to the tin-plated area of ​​the grounding piece, with the conductive adhesive in contact with the base adhesive, and then fix the grounding piece onto the conductive adhesive.

[0010] Step 5: After machining the tail rotor blade to the bushing boring state, measure the resistance value between the leading edge iron tip and the leading edge bushing. The resistance value R should be within the range of 0~1Ω. If the resistance value requirement is not met, use epoxy conductive adhesive to fill the gap in the contact area between the grounding plate and the rotor root bushing, and remeasure the resistance value.

[0011] The beneficial effects of this invention are as follows: A portion of the adhesive film is cut off at the end near the propeller root; the area corresponding to the cut-off area is the tin-plated area of ​​the grounding plate. A certain width of adhesive film is reserved on the outer periphery of the tin-plated area of ​​the grounding plate to increase the adhesion between the leading edge cladding and the tail rotor blade. Conductive adhesive is applied to the tin-plated area of ​​the grounding plate. The conductive adhesive has good adhesion and conductivity, ensuring the equipotential of the tail rotor blade. The grounding plate is fixed on the conductive adhesive. After molding, the resistance value between the tip of the leading edge cladding and the leading edge bushing is measured. The resistance value must meet the requirement of R≤1Ω to ensure conductivity. If the resistance value requirement is not met, the gap in the contact area between the grounding plate and the propeller root bushing is filled and repaired with epoxy conductive adhesive. The leading edge cladding installed by this invention has good fixing performance, excellent conductivity, and avoids problems such as adhesive detachment and missing adhesive.

[0012] Preferably, in step three, a 5mm wide adhesive film is reserved on the top and side of the tin-plated area of ​​the grounding sheet.

[0013] Preferably, the tin-plated area of ​​the grounding sheet in step two is rectangular. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the tail rotor blade processing according to a process for improving the bonding strength of the leading edge cladding iron according to the present invention.

[0015] Figure 2 This is a schematic diagram of traditional adhesive film bonding process;

[0016] Figure 3 This is a schematic diagram of the adhesive film used in a process to improve the bonding strength of the leading edge of the iron-clad frame according to the present invention.

[0017] Figure 4 A schematic diagram of the traditional process of bonding iron-clad film to the leading edge;

[0018] Figure 5 This is a schematic diagram of the adhesive film bonding process for improving the bonding strength of the leading edge iron-clad structure according to the present invention.

[0019] 1. Grounding plate, 2. Leading edge cladding, 3. Tail blade, 4. Adhesive film, 5. Tin-plated area of ​​grounding plate, 6. Conductive adhesive. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0021] See the appendix of this invention. Figures 1 to 5According to an embodiment of the present invention, a process for improving the bonding strength of the leading edge of the cladding iron is characterized by comprising the following steps:

[0022] Step 1: First, spray primer onto the inner surface of the leading edge cladding 2; then directly bond the leading edge cladding 2 to the leading edge of the tail rotor blade 3.

[0023] Step 2: Apply a layer of adhesive film 4 on the base adhesive. Adhesive film 4 is used to fix and bond the leading edge cladding iron to the tail rotor blade 3. Cut off part of the adhesive film at the end of the leading edge cladding iron near the root of the tail rotor blade, and the area corresponding to the cut-off area of ​​the adhesive film is the tin-plated area of ​​the grounding plate 5.

[0024] Step 3: Leave a certain width of adhesive film on the outer periphery of the tin-plated area 5 of the grounding sheet;

[0025] Step 4: Apply conductive adhesive 6 to the tin-plated area of ​​the grounding piece. The conductive adhesive 6 contacts the base adhesive, and the grounding piece 1 is then properly and firmly bonded to the conductive adhesive.

[0026] Step 5: After machining the tail rotor blade to the bushing boring state, measure the resistance value between the leading edge iron tip and the leading edge bushing. The resistance value must meet the requirement of 0Ω≤R≤1Ω. If the resistance value requirement is not met, use epoxy conductive adhesive to fill the gap in the contact area between the grounding plate and the rotor root bushing, and remeasure the resistance value.

[0027] Specifically, in step three, a 5mm wide adhesive film is reserved on the top and sides of the tin-plated area of ​​the grounding sheet.

[0028] To achieve conductivity between the grounding plate and the leading edge cladding, the design drawings require that the adhesive film on the working surface be cut off by 20mm×20mm in the tin-plated area of ​​the grounding plate. That is, at the end of the leading edge cladding near the root of the tail rotor blade, there is only base adhesive but no adhesive film, which cannot play a role in bonding the tail rotor blade composite material to the stainless steel cladding. This is a non-adhesive area, which may lead to delamination.

[0029] Specifically, the tin-plated area 5 of the grounding plate in step two is rectangular. Its width and length dimensions are 15×23mm.

[0030] This invention optimizes the bonding between the leading edge cladding and the grounding plate. Specifically, a 5mm wide adhesive film is added around the perimeter of the leading edge cladding area where the adhesive film has been cut off. This allows for the application of conductive adhesive to the central area without adhesive film during molding, and also allows the use of conductive adhesive to fill and repair gaps in the contact area between the grounding plate and the propeller root bushing, while ensuring a resistance value R ≤ 1Ω. This avoids the problem of leading edge cladding detachment caused by traditional processing methods.

[0031] The apparatus and methods disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments. For relevant details, please refer to the method section.

[0032] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A process for improving the bonding strength of the leading edge of the cladding iron, characterized in that, Includes the following steps: Step 1: First, spray primer onto the inner surface of the leading edge cladding (2); then directly bond the leading edge cladding (2) to the leading edge of the tail rotor blade (3). Step 2: A layer of adhesive film (4) is pasted on the base adhesive. The adhesive film (4) is used to fix and bond the leading edge iron to the tail rotor blade (3). Part of the adhesive film is cut off at the end of the leading edge iron near the root of the tail rotor blade, and the area corresponding to the cut-off area of ​​the adhesive film is the tin-plated area of ​​the grounding piece (5). Step 3: Leave a certain width of adhesive film on the outer periphery of the tin-plated area (5) of the ground sheet; Step 4: Apply conductive adhesive (6) to the tin-plated area of ​​the grounding piece. The conductive adhesive (6) is in contact with the base adhesive, and the grounding piece (1) is fixedly bonded to the conductive adhesive. Step 5: After machining the tail rotor blade to the bushing boring state, measure the resistance value between the leading edge iron tip and the rotor root bushing. The resistance value R should be 0 to 1Ω. If the resistance value requirement is not met, use epoxy conductive adhesive to fill the gap in the contact area between the grounding plate and the rotor root bushing, and remeasure the resistance value.

2. The process for improving the bonding strength of the leading edge cladding iron according to claim 1, characterized in that, The tin-plated area (5) of the grounding sheet in step two is rectangular.

3. The process for improving the bonding strength of the leading edge cladding iron according to claim 1, characterized in that, In step three, a 5mm wide adhesive film is reserved on the outer periphery of the tin-plated area of ​​the grounding sheet.

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