Method for inhibiting sealant redundancy from being squeezed into oil tank and oil tank

Abstract

The invention relates to the technical field of aerospace, in particular to a method and device for inhibiting sealant redundancy from being squeezed into an oil tank. The method provided by the embodiment of the invention comprises the steps that an annular groove is machined in the assembling face, used for installing a composite cover body, of a composite oil tank body; wherein the assembling face is located on the bottom face of a sunken structure, sunken inwards, of the outer surface of the composite material oil tank, and the shape of the sunken structure is matched with the shape of the composite material cover body; a sealing strip matched with the groove is placed in the groove; coating a sealant between the sealing strip and the side surface of the concave structure; and the composite material cover body is embedded into the sunken structure and fixed. A groove is formed in the assembling face, a sealing strip is placed in the groove, and the height, higher than the assembling face, of the sealing strip can play a directional restraining role in the extrusion flow direction of the sealant. And meanwhile, a sealant smearing construction process is matched, so that the two assembly surfaces can be uniformly extruded from one side without the sealing strip when the sealant is attached to the two assembly surfaces.

Description

Technical Field

[0001] The invention relates to the field of aerospace technology, and in particular to a method and a device for inhibiting excess sealant from squeezing into an oil tank. Background Art

[0002] As aircraft develop towards higher speeds and longer ranges, reducing the weight of aircraft is one of the important measures to meet these requirements under the condition that the thrust of aircraft engines is limited. At present, the outer shell of aircraft has gradually transitioned from metal to composite materials, and then from metal fuel tanks to composite fuel tanks.

[0003] With the continuous technological iteration of aircraft, the internal structure of aircraft is becoming increasingly complex. Compared with metal fuel tanks, the great advantage of using composite fuel tanks is that composite materials can be prepared on the go, which can make full use of the scattered space inside the aircraft cabin and maximize the use of cabin space.

[0004] Due to the limitations of the composite material thermoforming demolding process, a complete composite material fuel tank is often assembled from multiple composite parts. In order to prevent leakage from the composite material fuel tank, a large amount of sealant is used during the assembly process.

[0005] This assembly method will inevitably squeeze the sealant into the fuel tank, eventually causing excess material to be produced inside the fuel tank. If the movable excess material produced inside the fuel tank flows into the engine pipeline, the engine pipeline will be blocked at best, resulting in insufficient engine thrust, or even causing the engine to stop in mid-air, causing immeasurable losses. Summary of the invention

[0006] The embodiment of the present invention provides a method and a device for preventing excess sealant from squeezing into an oil tank, which can prevent excess sealant from squeezing into an oil tank.

[0007] In a first aspect, an embodiment of the present invention provides a method for preventing excess sealant from squeezing into a fuel tank, comprising:

[0008] An annular groove is machined on the assembly surface of the composite fuel tank body for mounting the composite cover; wherein the assembly surface is located on the bottom surface of a concave structure that is inwardly concave on the outer surface of the composite fuel tank, and the shape of the concave structure matches the shape of the composite cover;

[0009] placing a sealing strip matching the groove in the groove;

[0010] applying a sealant between the sealing strip and the side surface of the recessed structure;

[0011] The composite material cover is embedded in the recessed structure and fixed.

[0012] In a possible design, applying a sealant between the sealing strip and the side surface of the recessed structure includes:

[0013] A sealant is coated between the sealing strip and the side of the recessed structure to obtain a sealant layer with an inclined surface; wherein the lower end of the sealant layer is located on one side of the sealing strip and is lower than the highest point of the sealing strip, and the higher end of the sealant layer is located on one side of the side wall of the recessed structure and is higher than the highest point of the sealing strip.

[0014] In a possible design, the inclination angle of the sealant layer is 15 to 30 degrees.

[0015] In one possible design, it also includes:

[0016] Punching holes on the composite fuel tank body and the composite cover to obtain coaxial through holes on the composite fuel tank body and the composite cover respectively;

[0017] Install a support plate nut at one end of the through hole of the composite material fuel tank body facing the inside of the composite material fuel tank;

[0018] The step of embedding the composite material cover into the recessed structure and fixing the composite material cover comprises:

[0019] The composite material cover is embedded in the recessed structure and fixed by bolts.

[0020] In a possible design, the support plate nut is fixed inside the composite fuel tank by a plurality of rivets.

[0021] In a possible design, the bolt is a countersunk bolt.

[0022] In a possible design, embedding the composite material cover into the recessed structure and fixing it by bolts includes:

[0023] Apply sealant evenly on the surface of the composite cover to be installed;

[0024] Embed the composite material cover body into the recessed structure, and fix the bolt on the support plate nut through the through hole;

[0025] Performing a first tightening operation on the bolt to squeeze the sealant out from the gap of the recessed structure;

[0026] When the sealant is in a semi-cured state, performing a second tightening operation;

[0027] Curing sealant.

[0028] In a possible design, the tightening force of the first tightening operation is 1-2 N·M, and the tightening force of the second tightening operation is 8-10 N·M.

[0029] In a possible design, the thickness of the sealant applied on the composite cover is less than 0.3 mm.

[0030] In a second aspect, an embodiment of the present invention provides a fuel tank prepared according to any of the above methods.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] In this embodiment, a groove is firstly processed on the assembly surface of the composite fuel tank body for mounting the composite cover, wherein the assembly surface is the bottom surface of the composite fuel tank recessed structure. Then, a sealing strip matching the size of the groove is placed in the groove, and the sealing strip needs to be higher than the assembly surface. A sealant is applied between the sealing strip and the side wall of the sealing structure, and the sealing strip blocks the sealant to prevent it from flowing into the interior of the composite fuel tank through the through hole in the center of the recessed structure. Finally, the composite cover is embedded in the recessed structure and fixed. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 is a schematic cross-sectional view of a fuel tank provided by an embodiment of the present invention;

[0035] Figure 2 is a cross-sectional schematic diagram of a fuel tank preparation process provided by an embodiment of the present invention;

[0036] Figure 3 It is a three-dimensional cross-sectional view of a fuel tank provided by an embodiment of the present invention.

[0037] In the figure:

[0038] 1-composite material body; 2-sealant; 3-support plate nut; 4-sealing strip; 5-composite material cover; 6-countsunk screw. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0040] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0042] like Figures 1 to 3 As shown, an embodiment of the present invention provides a method for preventing excess sealant from squeezing into an oil tank, comprising:

[0043] An annular groove is machined on the assembly surface of the composite fuel tank body for mounting the composite cover; wherein the assembly surface is located at the bottom surface of a concave structure that is inwardly concave on the outer surface of the composite fuel tank, and the shape of the concave structure matches the shape of the composite cover;

[0044] Place a sealing strip that matches the groove in the groove;

[0045] applying a sealant between the sealing strip and the sides of the recessed structure;

[0046] The composite material cover is embedded into the recessed structure and fixed.

[0047] In this embodiment, a groove is firstly processed on the assembly surface of the composite fuel tank body for mounting the composite cover, wherein the assembly surface is the bottom surface of the composite fuel tank recessed structure. Then, a sealing strip matching the size of the groove is placed in the groove, and the sealing strip needs to be higher than the assembly surface. A sealant is applied between the sealing strip and the side wall of the sealing structure, and the sealing strip blocks the sealant to prevent it from flowing into the interior of the composite fuel tank through the through hole in the center of the recessed structure. Finally, the composite cover is embedded in the recessed structure and fixed.

[0048] In this embodiment, after the groove is processed, it is necessary to grind the groove, and the groove is required to have no visible burrs. Before assembly, the contact parts of the two components to be installed need to be polished with 40-grit sandpaper. When polishing, be careful not to damage the internal fibers, and only polish the resin. Before formal installation, a trial installation can be carried out to promptly find any assembly discomfort and perform polishing.

[0049] It should be noted that after all operations such as grinding and drilling are completed, they need to be wiped clean with a cloth dipped in acetone. When placing the sealing strip, the grooves on the composite assembly surface should be blown clean with an air gun and wiped clean with a cloth dipped in acetone. Before placing the sealing strip, it should be wiped clean with acetone and dried.

[0050] In the present invention, the sealant is prepared according to the ratio in the sealant manual. The multi-component sealant must be prepared strictly according to the ratio in the manual, and the weighing is carried out using an electronic scale (with an accuracy of not less than 0.01 grams) in an environment without external interference. After weighing, the multiple groups of sealants must be fully stirred, and the sealants must be placed in a semi-fluid state before use.

[0051] In some embodiments of the present invention, applying a sealant between the sealing strip and the side of the recessed structure comprises:

[0052] A sealant is coated between the sealing strip and the side of the recessed structure to obtain a sealant layer with an inclined surface; wherein the lower end of the sealant layer is located on one side of the sealing strip and is lower than the highest point of the sealing strip, and the higher end of the sealant layer is located on one side of the side wall of the recessed structure and is higher than the highest point of the sealing strip.

[0053] In this embodiment, the high end of the sealant layer is higher than the highest point of the sealing strip, so that the composite material cover body is preferentially in contact with the sealant layer portion at the high end to complete the sealing. At the same time, the sealing can be continuously ensured during the process of the composite material cover body continuing to be pressed down. In addition, the excess sealant will also be discharged through the gap of the side wall of the recessed structure and will not enter the interior of the oil tank. Since the low end of the sealant layer is lower than the highest point of the sealing strip, during the descent of the composite material cover body, even if there is a slight height change at the low end, it will not exceed the sealing strip. After the sealing material cover body contacts the sealing strip, the sealant can be completely isolated from the outside.

[0054] In some embodiments of the present invention, the inclination angle of the sealant layer is 15-30°.

[0055] In this embodiment, when the inclination angle is 15 to 30 degrees, it is easy to implement and can ensure the suppression and sealing effects.

[0056] In some embodiments of the present invention, it further includes:

[0057] Performing matching drilling on the composite fuel tank body and the composite cover body, and obtaining coaxial through holes on the composite fuel tank body and the composite cover body respectively;

[0058] Install a support plate nut at one end of the through hole of the composite material fuel tank body facing the inside of the composite material fuel tank;

[0059] The composite material cover is embedded in the recessed structure and fixed, including:

[0060] The composite material cover is embedded into the recessed structure and fixed by bolts.

[0061] In this embodiment, the support plate nut can ensure the sealing of the connection, and the coaxial through hole and the bolt can seal and fasten the cover body and the oil tank.

[0062] After drilling the through hole, wipe the composite assembly surface with a cloth dipped in acetone until there is no visible particle left on the surface of the cloth. After wiping, let it stand for 30 minutes to allow the assembly surface to dry completely.

[0063] Clean the inside of the fuel tank before bonding the sealant to ensure that there is no excess material left inside the tank.

[0064] Apply the bonding primer to the bolts and through holes, and let it dry for 30 minutes after application. Apply the bonding primer to the assembly surface as well. Use a brush to evenly apply the bonding primer to the assembly surface of the composite fuel tank body and the composite cover body, and let it dry for 30 minutes after application. It is strictly forbidden to touch the assembly surface with your hands during the operation and after application. If the assembly surface is contaminated, the contaminated assembly surface must be re-applied with bonding primer.

[0065] In some embodiments of the present invention, the support plate nut is fixed inside the composite fuel tank by a plurality of rivets.

[0066] In this embodiment, uniform force is applied when tightening the rivets to ensure that the airtight support plate nut is tightly attached to the composite wall without shaking.

[0067] In some embodiments of the present invention, the bolt is a countersunk bolt.

[0068] In this embodiment, the countersunk bolts can make the entire surface of the oil tank smooth.

[0069] In some embodiments of the present invention, the composite material cover is embedded in the recessed structure and fixed by bolts, including:

[0070] Apply sealant evenly on the surface of the composite cover to be installed;

[0071] The composite material cover is embedded into the recessed structure, and the bolts are fixed to the support plate nuts through the through holes;

[0072] Performing a first tightening operation on the bolt to squeeze the sealant out from the gap of the recessed structure;

[0073] When the sealant is in a semi-cured state, the second tightening operation is performed;

[0074] Curing sealant.

[0075] In this embodiment, applying different forces when the sealant is in different flow states can ensure that the excess sealant is discharged while having better sealing performance and better installation strength.

[0076] In some embodiments of the present invention, the tightening force of the first tightening operation is 1-2 N·M, and the tightening force of the second tightening operation is 8-10 N·M.

[0077] In some embodiments of the present invention, the thickness of the sealant applied on the composite cover is less than 0.3 mm.

[0078] An embodiment of the present invention provides a fuel tank, which is prepared according to any one of the above methods.

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for inhibiting excess sealant from squeezing into a fuel tank, characterized in that: include: An annular groove is machined on the assembly surface of the composite fuel tank body for mounting the composite cover; wherein the assembly surface is located on the bottom surface of a concave structure that is inwardly concave on the outer surface of the composite fuel tank, and the shape of the concave structure matches the shape of the composite cover; placing a sealing strip matching the groove in the groove; applying a sealant between the sealing strip and the side surface of the recessed structure; The composite material cover is embedded in the recessed structure and fixed.

2. The method according to claim 1, characterized in that The step of applying a sealant between the sealing strip and the side surface of the recessed structure comprises: A sealant is coated between the sealing strip and the side of the recessed structure to obtain a sealant layer with an inclined surface; wherein the lower end of the sealant layer is located on one side of the sealing strip and is lower than the highest point of the sealing strip, and the higher end of the sealant layer is located on one side of the side wall of the recessed structure and is higher than the highest point of the sealing strip.

3. The method according to claim 2, characterized in that The inclination angle of the sealant layer is 15 to 30 degrees.

4. The method according to claim 1, characterized in that Also includes: Punching holes on the composite fuel tank body and the composite cover to obtain coaxial through holes on the composite fuel tank body and the composite cover respectively; Install a support plate nut at one end of the through hole of the composite material fuel tank body facing the inside of the composite material fuel tank; The step of embedding the composite material cover into the recessed structure and fixing the composite material cover comprises: The composite material cover is embedded in the recessed structure and fixed by bolts.

5. The method according to claim 4, characterized in that The support plate nut is fixed inside the composite material oil tank by a plurality of rivets.

6. The method according to claim 4, characterized in that The bolt is a countersunk bolt.

7. The method according to claim 4, characterized in that The step of embedding the composite material cover into the recessed structure and fixing it by bolts comprises: Apply sealant evenly on the surface of the composite cover to be installed; Embed the composite material cover body into the recessed structure, and fix the bolt on the support plate nut through the through hole; Performing a first tightening operation on the bolt to squeeze the sealant out from the gap of the recessed structure; When the sealant is in a semi-cured state, performing a second tightening operation; Curing sealant.

8. The method according to claim 7, characterized in that The tightening force of the first tightening operation is 1 to 2 N·M, and the tightening force of the second tightening operation is 8 to 10 N·M.

9. The method according to claim 7, characterized in that: The thickness of the sealant applied on the composite cover is less than 0.3 mm.

10. A fuel tank, characterized in that: Prepared according to any one of claims 1 to 9.

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