CN114102501B

CN114102501B - Decomposition method of rivet on composite material closed tubular beam

Info

Publication number: CN114102501B
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: 2023-05-23
Anticipated expiration: 2041-11-03
Also published as: CN114102501A

Abstract

The invention belongs to the technical field of repair of composite material structures, and particularly relates to a method for decomposing rivets on a composite material closed tubular beam. By pre-placing an adhesive strip with proper adhesive properties and physical state on the back of the rivet, the excess such as pier heads and scraps 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 problem of decomposing rivets in a closed tubular beam, and the method of opening a maintenance hole, taking out the redundant materials of the decomposed rivets from the tubular beam and plugging the hole is adopted to prevent the redundant materials such as a rivet rod, a rivet pier head and the like after the rivet is decomposed from falling into the tubular beam of a helicopter, thereby avoiding damage to products caused by abnormal sound or long-term impact of the rivet pier head on the tubular beam part in the subsequent helicopter flight process.

Description

Decomposition method of rivet on composite material closed tubular beam

Technical Field

The invention belongs to the technical field of repair of composite material structures, 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 helicopter front cabin cover structure, is a tubular part with an appearance, and is subjected to end plugging after preliminary cementing. Riveting is often performed on tubular beam structures to ensure connection strength or to meet various personalized requirements, such as riveting brackets for connecting interior trim, finished products, other parts, etc.

When the riveted rivet has a problem or the rivet needs to be disassembled due to a change in demand in a subsequent use process, the disassembly of the rivet becomes a difficult problem. Because rivet pier or other piece that produces when breaking down the rivet can fall into tubular beam part inside and become the surplus, can abnormal sound because of the collision between surplus and the tubular beam part in the follow-up helicopter flight, perhaps the long-term striking tubular beam part of rivet pier causes the damage of product.

When the closed tubular beam structure is in an unfilled part or subassembly state, the current conventional treatment method is: and (3) decomposing the rivet by using a conventional rivet decomposing tool, guiding and judging the position of the redundant substance falling inside the tubular beam by shaking the tubular beam after decomposing the redundant substance, punching a glue injection hole and a glue overflow hole near the position, injecting the glue through the glue injection hole, and stopping injecting the glue when the glue solution flows out from the glue overflow hole. The glue injection can wrap the surplus substances by the glue solution, and the glue solution can fix the surplus substances inside the glue solution after being solidified, so that the surplus substances 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 using dry glass cloth glue dipping.

The original process method has the following defects:

1) The problem that the surplus exists after the rivet is decomposed when the closed tubular beam structure is in the state of the unfired part or the small assembly can only be solved, and the problem that the surplus exists after the rivet in the state that the tubular beam is completely installed is solved;

2) When the problem that the surplus exists after the rivet is decomposed when the closed tubular beam structure is in an unfired part or small assembly state is solved, at least two holes need to be additionally formed, one is a glue injection hole during glue injection, the other is a glue overflow hole during glue injection, the number of the formed holes is large, the requirement on the formed holes is high, and the surplus cannot be effectively wrapped and fixed due to the fact that the formed holes are wrong;

3) The amount of injected glue is relatively large. Because only rough judgment can be made on the positions of the redundant objects, and the positions of the tubular beams are different, the positions of the redundant objects are different, so that holes are drilled at the positions where the rivet accessories are relatively safe, glue injection quantity is required to reach the situation that glue overflows from the glue overflow holes, and the situation that the accuracy of judging the positions of the rivet pier is not high frequently happens, and the perforating positions are far away from the positions of the rivets, so that the glue injection quantity is overlarge; for helicopters, weight is a critical parameter, and injection of glue increases the weight of the part;

4) The success rate is not high. Because the redundant pieces are more, the redundant pieces are not completely fixed in the glue solution after the glue is injected, and the redundant pieces which can move freely still exist; or the cementing interface between the glue solution and the inside of the pipe beam is not firm, so that the solidified glue solution block can shake in the inside of the pipe beam.

Disclosure of Invention

The purpose of the invention is that: the invention belongs to repair technology of a composite material structure of a closed cavity (a part is a closed structure or is formed into the closed structure through subsequent connection), and relates to a method for decomposing rivets on a closed composite material tubular beam without leaving pier heads or other fragments (redundant matters) of the rivets in a closed space.

The technical scheme of the invention is as follows: in order to achieve the above object, a method for decomposing rivets on a composite material closed tubular beam is provided, comprising the following steps:

s1: determining a maintenance hole position on the opposite side of the position of the rivet to be decomposed on the closed tubular beam by searching a datum point for size measurement or by directly leading wires;

s2: a maintenance hole is formed;

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

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

s5: performing rivet decomposition;

s6: compacting the adhesion strip by external force to enable the rivet decomposition products to be fully adhered;

s7: removing the adhesive strip from the service hole;

s8: and plugging the maintenance hole.

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

In one possible embodiment, the adhesive strip is selected from butyl rubber having multiple components.

In one possible embodiment, in the step S2, a drill or a reamer dedicated to machining the composite material is used to open the maintenance hole.

In a possible embodiment, in the step S3, a flexible rod-shaped tool with a soft cleaning head is used, the cleaning head is dipped with an organic solvent and extends into the maintenance hole, so that the interior of the closed tubular beam is cleaned.

In one possible embodiment, in said step S4, said adhesive strip has a diameter smaller than the maintenance hole size, and said adhesive strip is transported inside the closed tubular beam using a rigid rod-shaped tool.

In one possible embodiment, in said step S5, rivet breaking is performed using a drilling method or a rivet breaker.

In one possible embodiment, in the step S8, the maintenance hole is plugged with a normal temperature glue and a dry glass cloth.

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

the invention aims to solve the problem of decomposing rivets in a closed tubular beam, and the method of opening a maintenance hole, taking out the redundant materials of the decomposed rivets from the tubular beam and plugging the hole is adopted to prevent the redundant materials such as a rivet rod, a rivet pier head and the like after the rivet is decomposed from falling into the tubular beam of a helicopter, thereby avoiding damage to products caused by abnormal sound or long-term impact of the rivet pier head on the tubular beam part in the subsequent helicopter flight process.

The method has the following advantages:

1) The applicability is wide. The method is suitable for decomposing rivets on the composite material closed tubular beam in an uninstalled state of parts or components and the like, and is also suitable for decomposing rivets on the composite material closed tubular beam in an installed state; the rivet decomposition method can be popularized to rivet decomposition on the structures of all composite material closed cavities (the parts are closed structures or are closed structures through subsequent 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 excessive materials such as the rivet rod, the rivet pier head and the like after the decomposed rivet is completely taken out after the scheme is implemented can be ensured to fall off, and the risks of residue and failure are extremely low;

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

4) The implementation effect is good. The method has the advantages that the surplus is removed from the closed composite material tubular beam, so that the risk that the adhesive block and the tubular beam interface are poor in combination and the whole adhesive block can move freely in the previous method for fixing the surplus by using the adhesive is avoided;

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

6) Without increasing the weight. Since the surplus material after the rivet is decomposed is completely taken out and a large amount of glue solution is not required for fixing the surplus material, the repairing process does not increase the weight.

Drawings

FIG. 1 is an exploded view of a rivet on a closed tubular beam in accordance with a preferred embodiment of the present invention

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

Detailed Description

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

The main technical conception adopted by the invention is as follows: by pre-placing an adhesive strip with proper adhesive properties and physical state on the back of the rivet, the excess such as pier heads and scraps 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, a connecting bracket 001, a closed tubular beam 002, a rivet 003 and an adhesive strip 004. The specific implementation steps are as follows:

1. determining an open maintenance hole position

Determining a maintenance opening position on the opposite side of the riveting rivet position of the closed tubular beam by searching a reference point for size measurement or by directly leading wires, ensuring that the center of the maintenance opening position is basically opposite to the rivet, and marking a cross line on the searched position;

2. opening maintenance holes

Machining a maintenance hole with the diameter of 10mm by using a special drill bit or a drill for machining a composite material with a marked cross line as a center, and cleaning fiber powder and scraps by using a dust collector with negative pressure in the process of opening the maintenance hole 10 as shown in fig. 1;

3. cleaning the inside of a tubular beam

1) Preparing aluminum wires with the diameter of about phi 2mm or rod-shaped objects with similar performances, wherein the length of the aluminum wires is required to be more than or equal to 2 times of the cross section size of the tubular beam;

2) Preparing a small piece of cleaning cloth, wherein the diameter size of the cleaning cloth after being wound into a group is required to be smaller than 10mm;

3) Winding and fixing cleaning cloth on aluminum wires or rod-shaped objects with similar performances to manufacture a cleaning tool;

4) A cleaning tool is used for dipping in a solvent (such as acetone, butanone, ethanol or ethyl acetate) and then extending into the maintenance hole to wipe and clean the position of the riveting rivet. The rigidity and toughness of the aluminum wire are suitable, so that the aluminum wire can maintain good rigidity when being bent to a certain extent.

5) The method of 2) to 4) is repeatedly used for cleaning until no stain exists on the cleaning cloth.

And (5) finishing cleaning the inside of the tubular beam.

4. Preparation of adhesive strips

The adhesive strip is butyl rubber added with multiple components, and the added multiple components have the adjusting functions of 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; the adhesive has proper viscosity, high viscosity under the action of pressure, and the adhesion force is related to the pressure value, but can be separated from the paved surface under the action of external force without residue. This can also be accomplished using materials that are comparable to the adhesive strips.

1) Because of the excellent extensibility of the adhesive strips, the adhesive strips can be stretched into any size and any shape (the size is smaller than the original size range of the adhesive strips). Stretching the adhesive strip into an elongated strip with the diameter of about phi 8mm, wherein the length of the elongated strip is required to be more than or equal to 5 times of the cross section size of the tubular beam;

2) Preparing a rod-shaped tool with certain rigidity and diameter smaller 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. Adhesive strip

1) Conveying the adhesive strips into the tubular beam through maintenance holes with the diameter smaller than phi 10mm by using a rod-shaped tool;

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, enabling the adhesive strips to completely wrap the rivet pier heads, and compacting the adhesive strips;

4) Leaving a portion of the adhesive strip outside the tubular beam for subsequent cleaning;

5) The adhesive strip left outside the tubular beam is stretched by the micro-applied force, so that the adhesive strip is ensured to be adhered to the back of the rivet pier head.

And (5) finishing the sticking of the adhesive tape.

6. Decomposing rivet

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

1) Checking a drawing, namely clearly determining the types (solid rivet, blind rivet, countersunk rivet, round head rivet or half round head rivet and the like), the diameters, the lengths and other information of the rivets, and selecting a proper rivet decomposition method according to the types and the sizes of the rivets;

2) Drilling holes from the center position of one side of the nail head part by using a drill bit which is one level smaller than the nominal diameter of the rivet rod (the self-plugging rivet has the same diameter as the rivet), wherein the drilling depth needs to be controlled to be close to but not exceed the height of the nail rod until the rivet head falls off, and structural members are not damaged;

3) Using a punch with the same nominal diameter as the rivet stem to punch off the residual rivet stem and pier head parts;

4) Due to the excellent pressure sensitivity of the adhesive strip, the force of punching out the pin and the pier head portions tightly adheres the punched-out surplus material within the adhesive strip.

7. Compacted adhesive strip

In order to further ensure that the flushed surplus substances are completely adhered into the adhesive strips, external force is applied to the positions of the adhesive strips to compact the adhesive strips, and the flushed surplus substances are completely sunk into the adhesive strips after being compacted due to the excellent pressure sensitivity of the adhesive strips, so that the flushed surplus substances are ensured not to fall off from the adhesive strips.

8. Removing the adhesive strip

The adhesive strip part left outside the maintenance hole is pulled by traction force due to proper viscosity of the adhesive strip, and the whole section of the adhesive strip containing the surplus material is taken out from the tubular beam through the maintenance hole, so that the surplus material left inside the tubular beam after the rivet is decomposed is taken out of the tubular beam.

9. Hole plugging

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

1) Polishing the maintenance area Kong Zhouquan mm by using 200-mesh sand paper;

2) Preparing dry glass cloth, cutting into small blocks with the sizes of phi 20mm, phi 30mm and phi 40mm respectively, and adding 3 layers;

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

4) Dipping: immersing 3 layers of dry glass cloth into prepared EA9396 glue, scraping the glue by using a pressing plate, so that the glue dipping is uniform and the wrapped bubbles are removed;

5) Spreading the dipped glass cloth layer by layer at the position of the straight maintenance hole, and paying attention to the concentricity of the glass cloth spreading layer and the maintenance hole as much as possible;

6) Curing: curing is completed at normal temperature for 7 days or at 65 ℃ for 1 hour;

7) Cleaning: cleaning redundant glue tumors;

and (3) paint repairing: the same paint as the original product is added in the repair area.

When the rivet used for disassembling the connecting pipe beam and the connecting bracket 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 machining modification, the riveted bracket on the cabin cover tube beam is required to be disassembled, and a new equipment bracket is required to be reinstalled. Because the tubular beam is a closed structure, the decomposed rivet pier head is left inside the tubular beam, and great hidden danger is caused for subsequent aircraft use. By applying the invention, the purpose of taking out the rivet pier head in the process of disassembling the rivet is successfully realized.

Claims

1. The method for decomposing the rivet on the composite material closed tubular beam is characterized by comprising the following steps of:

s2: a maintenance hole is formed;

s5: performing rivet decomposition;

s7: removing the adhesive strip from the service hole;

s8: and plugging the maintenance hole.

2. A method of decomposing rivets on a composite material closed tubular beam as claimed in claim 1, characterized in that said adhesive strips are of a viscoelastic rubber material.

3. A method of decomposing rivets on a composite material closure tube beam as claimed in claim 2, characterized in that said adhesive strips are made of butyl rubber having a plurality of components.

4. The method for disassembling rivets on a composite material closed tubular beam according to claim 1, characterized in that in the step S2, a drill bit or a reamer dedicated to machining the composite material is used for forming the maintenance hole.

5. The method according to claim 1, wherein in the step S3, a flexible rod-shaped tool with a soft cleaning head is used, the cleaning head is dipped with an organic solvent, and the cleaning head is inserted into the maintenance hole to clean the inside of the closed tubular beam.

6. A method of breaking down rivets on a composite material closure tube beam according to claim 1, characterized in that in step S4 the adhesive strips have a diameter smaller than the maintenance hole size and are fed into the interior of the closure tube beam by means of a rigid rod-shaped tool.

7. A method of decomposing rivets on a composite material closed tubular beam as claimed in claim 1, characterized in that in said step S5 rivet decomposition is performed using a drilling method or a rivet decomposer.

8. The method for disassembling rivets on a composite material closed tubular beam according to claim 1, characterized in that in said step S8, maintenance holes are plugged with normal temperature glue and dry glass cloth.