CN114102501A

CN114102501A - Method for decomposing rivets on composite material closed tubular beam

Info

Publication number: CN114102501A
Application number: CN202111293529.3A
Authority: CN
Inventors: 祁书涛; 吕知先; 王春艳; 张超
Original assignee: Harbin Aircraft Industry Group Co Ltd
Current assignee: Harbin Aircraft Industry Group Co Ltd
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2022-03-01
Anticipated expiration: 2041-11-03
Also published as: CN114102501B

Abstract

The invention belongs to the technical field of composite material structure repair, and particularly relates to a method for decomposing rivets on a composite material closed tubular beam. By placing the adhesive strip with proper adhesive property and physical state on the back of the riveting rivet in advance, the remainders such as pier heads, scraps and the like generated by decomposing the rivet can be fixed in the adhesive strip instead of falling into the tubular beam part. The invention aims to solve the decomposition problem of the rivet in the closed tubular beam, and avoids the nail rod, the rivet pier head and other redundancies falling into the tubular beam of the helicopter after the rivet is decomposed by opening the maintenance hole and taking out and blocking the hole of the redundancy of the decomposed rivet from the tubular beam by using the adhesive strip, thereby avoiding the damage of the product caused by abnormal sound or long-term impact of the rivet pier head on the tubular beam parts in the subsequent flying process of the helicopter.

Description

Method for decomposing rivets on composite material closed tubular beam

Technical Field

The invention belongs to the technical field of composite material structure repair, and particularly relates to a method for decomposing rivets on a composite material closed tubular beam.

Background

The composite material tubular beam is a supporting framework of a front cabin cover structure of the helicopter, is a tubular part with appearance, and is subjected to end plugging after preliminary bonding. Riveting is often performed on the tubular beam structure to ensure the connection strength or to meet various personalized requirements, such as riveting brackets for connecting interior trims, finished products, other parts, and the like.

Disassembling rivets can be a problem when the rivet is problematic or requires disassembly due to changing requirements during subsequent use. Because rivet pier heads or other fragments generated during rivet decomposition can fall into the tubular beam parts to become redundant, abnormal sound can be generated due to collision between the redundant parts and the tubular beam parts in the subsequent helicopter flying process, or the rivet pier heads impact the tubular beam parts for a long time to cause product damage.

When the closed tubular beam structure is in an uninstalled part or small assembly state, the current conventional treatment method is: and (3) decomposing the rivets by using a conventional rivet decomposing tool, dropping the decomposed surplus objects into the tubular beam part, guiding and judging the position of the surplus objects dropping into the tubular beam part by shaking the tubular beam, punching glue injection holes and glue overflow holes near the position, injecting glue through the glue injection holes, and stopping injecting glue when the glue flows out of the glue overflow port. The surplus objects can be wrapped by the glue solution through glue injection, and the surplus objects can be fixed inside the glue solution after the glue solution is solidified, so that the surplus objects are prevented from moving and colliding inside the tubular beam part, and abnormal sound and impact are avoided. The rivet hole, the glue injection hole and the glue overflow hole which are caused by the repairing method are plugged and repaired by soaking the dry glass cloth with glue.

The prior process method has the disadvantages that:

1) the problem that surplus exists after the rivet is decomposed when the closed tubular beam structure is in a state of parts or small assemblies which are not installed can be solved, and the problem that surplus exists after the rivet in an installed state is decomposed cannot be solved;

2) when the problem that redundant objects exist after the rivet is decomposed when a closed tubular beam structure is in a state of parts or small assemblies which are not installed is solved, at least two holes need to be additionally manufactured, one hole is a glue injection hole during glue injection, the other hole is a glue overflow hole during glue injection, the number of manufactured holes is large, the requirement on the manufactured hole position is high, and the redundant objects cannot be effectively wrapped and fixed due to the wrong manufactured hole position;

3) the amount of injected glue is relatively large. Because only rough judgment can be made on the position of the surplus objects, and the positions of the surplus objects are different due to different placing postures of the tube beam, holes need to be drilled at the positions where the rivet accessories are relatively safe, glue injection quantity needs to reach that glue overflow holes can overflow glue solution, and the positions of the holes are far away from the rivet positions due to low accuracy of judgment on the rivet pier positions, so that the glue injection quantity is overlarge; for the helicopter, the weight is a very critical parameter, and the injection of glue solution increases the weight of parts;

4) the success rate is not high. Because the excess debris is too much, the excess debris is not completely fixed in the glue solution after glue injection, and the excess debris capable of freely moving still exists; or the glue solution and the glue joint interface in the tubular beam are not firm, so that the whole solidified glue solution block shakes in the tubular beam.

Disclosure of Invention

The purpose of the invention is as follows: the invention belongs to a repair technology of a composite material structure of a closed cavity (parts are of closed structures or are of closed structures through subsequent connection), and relates to a method for decomposing rivets on a closed composite material tubular beam without leaving pier heads or other scraps (surplus objects) of the rivets in a closed space.

The technical scheme of the invention is as follows: in order to achieve the purpose, the invention provides a method for decomposing rivets on a composite closed tubular beam, which comprises the following steps:

s1: determining the position of a maintenance hole on the opposite side of the position of the rivet to be decomposed on the closed tubular beam by searching a reference point for size measurement or by a direct lead mode;

s2: forming a maintenance hole;

s3: cleaning the interior of the closed tubular beam through the maintenance hole;

s4: conveying the adhesive strip into the closed tubular beam through the maintenance hole, so that the adhesive strip is adhered to the back of the pier head of the rivet to be decomposed and is pressed tightly;

s5: performing rivet decomposition;

s6: compacting the adhesive strip through external force to ensure that the decomposed objects of the rivet are fully adhered;

s7: removing the adhesive strip from the service hole;

s8: and (5) plugging the maintenance hole.

In one possible embodiment, the adhesive strip is a viscoelastic rubber material.

In one possible embodiment, the adhesive strip is butyl rubber with multiple components.

In one possible embodiment, in step S2, the maintenance hole is drilled using a drill or a scribe hole dedicated to machining the composite material.

In one possible embodiment, in step S3, a bendable rod-shaped tool with a soft cleaning head at the head is used to dip organic solvent on the cleaning head and extend into the maintenance hole to clean the inside of the closed tubular beam.

In one possible embodiment, in step S4, the adhesive strip diameter is smaller than the service hole size, and a rigid rod-shaped tool is used to deliver the adhesive strip to the inside of the closed tubular beam.

In one possible embodiment, in the step S5, the rivet disassembling is performed using a drilling method or a rivet disassembling machine.

In one possible embodiment, in the step S8, the service hole is sealed by using normal temperature glue and dry glass cloth.

Compared with the prior art, the invention has the beneficial effects that:

the invention aims to solve the decomposition problem of the rivet in the closed tubular beam, and avoids the nail rod, the rivet pier head and other redundancies falling into the tubular beam of the helicopter after the rivet is decomposed by opening the maintenance hole and taking out and blocking the hole of the redundancy of the decomposed rivet from the tubular beam by using the adhesive strip, thereby avoiding the damage of the product caused by abnormal sound or long-term impact of the rivet pier head on the tubular beam parts in the subsequent flying process of the helicopter.

The method mainly has the following advantages:

1) the applicability is wide. The rivet disassembling device is suitable for disassembling the rivets on the composite material closed tubular beams in the non-installed state of parts or components and the like, and is also suitable for disassembling the rivets on the composite material closed tubular beams in the installed state; the rivet can be popularized to the rivet decomposition on all composite material closed cavity structures (parts are closed structures or are connected into closed structures through follow-up connection);

2) the reliability and the success rate are high. Due to the excellent performance of the adhesive strip and the reasonable design of the scheme, the method can ensure that the remainders such as the rivet rod, the rivet pier head and the like after the rivet is completely taken out and decomposed are dropped, and the risk of residue and failure is extremely low;

3) the operation is simple, and the practicability is strong. The used tools are common tools with easily available peripheries, and the requirements on the tools are simple; the adhesive strips are common auxiliary materials in the forming process of composite material products and are mature goods shelf products. The whole operation process has no difficulty, and the personnel with basic assembly work can realize the operation;

4) the implementation effect is good. Because the surplus materials are removed from the closed composite material tubular beam, the risks that the interface bonding property of the glue solution block and the tubular beam is poor and the glue solution block can move freely as a whole in the conventional method for fixing the surplus materials by using the glue solution are avoided;

5) the number of the openings is small, and the influence on the design strength is small. Because only one maintenance hole with the diameter of phi 10mm is formed, plugging is carried out after the operation is finished, and the influence on the structural strength is small;

6) the weight is not increased. The repair process does not increase the weight because the surplus after the rivet is disassembled is completely taken out and a large amount of glue solution is not needed for fixing the surplus.

Drawings

FIG. 1 is an exploded view of a rivet on a closed tubular beam according to a preferred embodiment of the present invention

001-connecting support 002-closed tubular beam 003-rivet 004-adhesive strip

Detailed Description

For a further understanding of the invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are included merely to further illustrate the features and advantages of the invention and are not intended to limit the invention to the claims.

The invention adopts the following main technical conception: by placing the adhesive strip with proper adhesive property and physical state on the back of the riveting rivet in advance, the remainders such as pier heads, scraps and the like generated by decomposing the rivet can be fixed in the adhesive strip instead of falling into the tubular beam part. As shown in fig. 1, connecting bracket 001, closed tubular beam 002, rivet 003, adhesive strip 004. The specific implementation steps are as follows:

1. determining open service hole location

Determining the position of a maintenance hole on the opposite side of the position of a rivet riveted by a closed tubular beam by searching a reference point for size measurement or by a direct lead mode, ensuring that the center of the position of the maintenance hole is basically opposite to the rivet, and marking a cross word line on the searched position;

2. opening maintenance holes

Taking a marked cross word line as a center, processing a maintenance hole with the diameter of phi 10mm by using a drill bit or a drilling drill special for processing composite materials, and cleaning fiber powder and debris by using a vacuum cleaner with negative pressure in the process of opening the maintenance hole 10 as shown in figure 1;

3. inside cleaning of tubular beams

1) Preparing an aluminum wire with the diameter of about phi 2mm or a rod-shaped object with similar performance, wherein the length of the aluminum wire is required to be more than or equal to 2 times of the section size of the tubular beam;

2) preparing a small piece of cleaning cloth, wherein the diameter size of the cleaning cloth is required to be less than 10mm after the cleaning cloth is wound into a block;

3) winding and fixing the cleaning cloth on an aluminum wire or a rod-shaped object with similar performance to prepare a cleaning tool;

4) and (4) dipping a cleaning tool into a solvent (acetone, butanone, ethanol or ethyl acetate and the like), and then extending into the maintenance hole to wipe and clean the position of the riveting rivet. Because the rigidity and the toughness of the aluminum wire are proper, the aluminum wire can keep better rigidity when being bent to a certain degree.

5) Repeatedly cleaning by using the methods 2) to 4) until the cleaning cloth is free from stains.

And finishing the cleaning of the interior of the tubular beam.

4. Preparing for adhesive strips

The adhesive strip is butyl rubber added with a plurality of components, and the added components have the functions of adjusting the performances such as viscosity, pressure sensitivity and the like. The adhesive strip has excellent ductility and high elongation at break; the adhesive has excellent pressure sensitivity, is sensitive to pressure, and can be well adhered to a paved surface after being pressed; has proper viscosity, and the viscosity is higher under the action of pressure, the adhesive force is related to the pressure value, but the separation from the paved surface can be realized under the external force without residue. This can also be done using a material with properties comparable to the adhesive strip.

1) The adhesive tape has excellent extensibility, and therefore, the adhesive tape can be stretched into a form having any size and any shape (the size is smaller than the original size range of the adhesive tape). Stretching the adhesive strip into an elongated strip with the diameter of 8mm, wherein the length of the elongated strip is required to be more than or equal to 5 times of the section size of the tubular beam;

2) preparing a rod-shaped tool with certain rigidity and the diameter of less than phi 10mm, wherein the rod-shaped tool has no special requirement, such as a wood stick, a pen container and the like with proper size;

the adhesive strip is ready.

5. Sticky adhesive strip

1) Using a rod-shaped tool to convey the adhesive strip into the tubular beam through a maintenance hole with the diameter smaller than phi 10 mm;

2) the adhesive strip is adhered to the back of the rivet pier head by utilizing the excellent pressure sensitivity and viscosity of the adhesive strip;

3) conveying as many adhesive strips as possible to enable the adhesive strips to completely wrap the rivet pier heads and tightly press the adhesive strips;

4) leaving a part of adhesive strips outside the tubular beam for subsequent cleaning;

5) and (3) slightly applying force to stretch the adhesive strip remained outside the tubular beam to ensure that the adhesive strip is adhered to the back of the rivet pier head.

And finishing the pasting of the pasting strip.

6. Disassembling rivet

The rivet is disassembled using a drilling method or using a rivet decomposer.

1) Checking a drawing, determining information such as the type (solid rivet, self-plugging rivet, countersunk rivet, round-head rivet or semi-round-head rivet) of the rivet to be decomposed, the diameter, the length and the like, and selecting a proper rivet decomposition method according to the type and the size of the rivet;

2) drilling a hole from the center of one side of the head of the rivet by using a drill bit which is one step smaller than the nominal diameter of the rivet rod (the diameter of the self-plugging rivet is the same as that of the rivet), wherein the drilling depth needs to be controlled to be close to but not more than the height of the rivet rod until the rivet head falls off, and structural parts cannot be damaged;

3) punching out the residual nail rod and pier head parts by using a punch with the same nominal diameter as the rivet rod;

4) due to the excellent pressure-sensitive property of the adhesive strip, the force of punching out the nail rod and the pier head part tightly adheres the punched-out excess in the adhesive strip.

7. Compaction adhesive strip

In order to further ensure that the punched excess is completely adhered into the adhesive strip, external force is applied to the position of the adhesive strip to compact the adhesive strip, and due to the excellent pressure-sensitive property of the adhesive strip, the punched excess is completely sunk into the adhesive strip after being compacted, so that the excess is ensured not to fall off from the adhesive strip.

8. Take out the adhesive strip

Due to the proper viscosity of the adhesive strip, the adhesive strip part remained outside the maintenance hole is pulled by traction force, and the whole section of the adhesive strip containing the surplus objects is taken out from the tubular beam through the maintenance hole, so that the surplus objects remained in the tubular beam after the rivets are disassembled are taken out of the tubular beam.

9. Plugging hole

And sealing the maintenance hole with the diameter of 10mm by using normal temperature glue and dry glass cloth.

1) Polishing the area of 20mm around the maintenance hole by using 200-mesh sand paper;

2) preparing dry glass cloth, cutting into small pieces with the sizes of phi 20mm, phi 30mm and phi 40mm respectively, and totally 3 layers;

3) glue mixing: preparing EA9396 glue, and recording the glue mixing time and the active period;

4) gum dipping: soaking 3 layers of dry glass cloth into prepared EA9396 glue, scraping the glue by using a pressing plate to ensure that the glue is uniformly soaked and the wrapped bubbles are removed;

5) paving the glass cloth after gum dipping at the straight maintenance hole layer by layer, and paying attention to the fact that the glass cloth paving layer is concentric with the maintenance hole as much as possible;

6) and (3) curing: the curing is finished at the normal temperature of 7 days or at the temperature of 65 ℃ for 1 hour;

7) cleaning: cleaning redundant glioma;

paint repair: and (4) repairing the same paint as the original product in the repairing area.

When the rivet for decomposing the connecting pipe beam and the connecting support is used, the rivet pier head and the rivet core are ensured not to be left inside the closed pipe beam. In the process of modifying a certain type machining, a riveted support on a cabin cover tubular beam needs to be disassembled, and a new equipment support needs to be installed again. Because the tubular beams are of a closed structure, the rivet pier heads after decomposition are left inside the tubular beams, and great hidden danger is caused to subsequent airplane use. By applying the invention, the purpose of taking out the rivet pier head in the rivet disassembling process is smoothly realized.

Claims

1. A method for decomposing rivets on a composite closed tubular beam is characterized by comprising the following steps:

s2: forming a maintenance hole;

s5: performing rivet decomposition;

s7: removing the adhesive strip from the service hole;

s8: and (5) plugging the maintenance hole.

2. The method of claim 1, wherein the adhesive strip is a viscoelastic rubber material.

3. The method of claim 2, wherein the adhesive strips are butyl rubber with multiple components.

4. The method of claim 1, wherein the step S2 is performed by drilling a maintenance hole with a drill or a scoring hole dedicated to composite material processing.

5. The method of claim 1, wherein in step S3, the inside of the closed tubular beam is cleaned by dipping an organic solvent into the cleaning head using a bendable rod-shaped tool having a soft cleaning head at the head thereof and extending into the maintenance hole.

6. The method of claim 1, wherein in step S4, the adhesive strip diameter is smaller than the service hole size, and a rigid rod tool is used to transport the adhesive strip into the interior of the closed tubular beam.

7. The method of claim 1, wherein the rivet disassembly is performed using a drill method or a rivet disassembly tool in the step S5.

8. The method for disassembling rivets on a composite closed tubular beam according to claim 1, wherein in the step S8, the service holes are sealed off by using normal temperature glue and dry glass cloth.