A method and a removal assembly for removing a bolt broken in a base body

Abstract

The present invention discloses a method and a removal assembly for removing a bolt broken in a substrate, belonging to the technical field of maintenance. The removal method includes: S1. Coating a high-temperature resistant lubricating oil to form a protective oil film, the inner and outer rings of the protective oil film respectively extending to the edge of the fracture and the surface of the substrate around the pit, so that the lubricating oil fills into the thread clearance; S2. Installing a high-temperature resistant protective sleeve in the pit and forming a flush stacking layer by laser powder cladding; S3. Forming a clamping end on the flush stacking layer by wire adding surfacing and making a clamping plane, and using a clamping tool to withdraw the residual bolt. The removal assembly includes a protective oil film, the protective oil film including an edge area, a peripheral area and a filling area. A high-temperature resistant protective sleeve provided with a flush stacking layer is installed in the pit, and a clamping end with a clamping plane at the top is welded on the flush stacking layer. The present invention can quickly remove the residual bolt without damaging the threaded hole, achieving the goal of quickly reusing the substrate.

Description

Technical Field

[0001] The present invention relates to the field of maintenance technologies, and particularly to a method and an assembly for removing a bolt broken in a base body. Background Art

[0002] Most aircraft carry external loads, such as auxiliary fuel tanks, weapons, data recorders, and suspensions. These loads need to be quickly, accurately, and sequentially released during flight. However, due to limitations in flight environment, test methods, and test funds, it is impossible to complete the function and accuracy verification tests of the release mechanism in the air. It is necessary to use dummy parts on the ground to conduct ground release tests. The dummy part base body refers to a part that has the same volume, the same weight, and a center of gravity position close to that of the released object (auxiliary fuel tank, weapon, recorder, suspension, etc.), and is also called a test dummy part. It can be used for ground tests, verification tests, and test analysis, etc., to test various performances of the aircraft. In the ground release test, after the dummy part base body is released, due to the action of gravity, the high-strength bolts located above or on the side of the dummy part quickly flip during the falling process and violently impact the bottom surface of the test recovery pit, resulting in all the connecting bolts being broken, and some high-strength bolts remaining in the dummy part base body, forming residual bolts. Since the bolts remaining in the dummy part lose their bolt clamping ends and cannot be stably removed by clamping and rotating with tools, the dummy part cannot be reinstalled on the aircraft to conduct subsequent tests, and the reuse is blocked and stopped.

[0003] The fake part matrix of the remaining bolt head. Depending on the breakage location, some remaining bolts protrude above the matrix surface and are easy to remove. However, more fracture surfaces extend below the surface of the fake part matrix, forming pits, and the remaining bolts cannot be removed. To achieve the purpose of reuse, the current engineering practice is to re-drill and tap the original hole position, only requiring the diameter of the new hole to be larger than that of the old hole, and at the same time using a special stepped bolt. But when drilling the new hole, to achieve sufficient connection strength, it is required to remove all the stress-deformed materials around the old hole. Therefore, the diameter of the new hole shall not be less than 1.4 times that of the old hole. With the increase in the diameter of the new hole, the bolt end of the corresponding bolt fastener also needs to be increased. This makes it necessary to carry out a large amount of long-term work after each ground drop test to complete the re-drilling and re-manufacturing of the fasteners, causing great uncertainty to the drop test. Re-making the connection holes and fasteners will lead to a reduction in production efficiency, an increase in labor intensity, and even frequent scrapping of expensive fake parts, which is not a feasible manufacturing process. For this reason, the patent with the patent number "201610733449.8" and the patent name "Method for Removing Broken Bolt Rod" proposes a method that does not require reaming, including the following steps: (1) Drilling: Use a punch to make a punch hole in the center of the top of the broken bolt, and then use an electric drill to drill a hole along the punch hole in the middle of the broken bolt; (2) Tapping: Tap a threaded hole opposite to the bolt thread in the hole; (3) Removing the bolt: Use a wrench to tighten the reverse-thread bolt to the bottom of the threaded hole, gently tap the top of the reverse-thread bolt wrench with a hammer, and then use the wrench to forcefully pull out the bolt. Although the above patent will not enlarge the original threaded hole, during the drilling and tapping process of the broken bolt, the mechanical disturbance generated easily deforms the thread of the original threaded hole, making it impossible to reuse. Summary of the Invention

[0004] The object of the present invention is to solve the above technical problems and provide a method and a removal assembly for removing a bolt broken in a matrix, mainly including three steps: protecting the thread with high-temperature-resistant lubricating oil, forming a flat stacking layer by laser powder cladding, and adding wire surfacing to reconstruct the clamping end. The lubricating oil can prevent the threaded hole from being damaged by high temperature and laser. The laser powder cladding technology flattens the fracture surface, and the formed flat stacking layer improves the weldability, ensuring that subsequent argon arc welding, gas welding or other welding technologies with poor weldability requirements but high welding efficiency can be used. A clamping end is surfacing-welded on the upper surface of the flat stacking layer to facilitate the clamping tool to withdraw the remaining bolt. It can quickly remove the remaining part of the connecting bolt without damaging the threaded hole, achieving the goal of rapid reuse of the matrix.

[0005] To achieve the above object, the present invention provides the following solution: The present invention discloses a method for removing a bolt broken in a matrix, including the following steps:

[0006] S1. Coat the pit formed by the threaded hole and the fracture of the residual bolt with high-temperature resistant lubricating oil to form an annular protective oil film. The outer ring of the protective oil film extends to the surface of the substrate around the pit, and the inner ring of the protective oil film extends to the edge of the fracture of the residual bolt, so that the lubricating oil fills into the thread clearance between the residual bolt and the threaded hole.

[0007] S2. Install a high-temperature resistant protective sleeve in the pit that can cover the protective oil film at the edge of the fracture. Use the laser powder cladding method to increase the height of the fracture in the high-temperature resistant protective sleeve until a flush stacking layer flush with the top surface of the high-temperature resistant protective sleeve is formed.

[0008] S3. Form a clamping end on the flush stacking layer by the wire feeding surfacing method, and make a clamping plane for the clamping tool to clamp on the top of the clamping end. Use the clamping tool to remove the residual bolt.

[0009] Preferably, before step S1, step S0 is included to clean the fracture and the surface of the substrate around the pit, and the fracture needs to be flattened during the cleaning process.

[0010] Preferably, the width of the part of the protective oil film on the surface of the substrate around the pit is not less than 2 times the diameter of the threaded hole; the width of the edge of the fracture is 0.05 - 0.2 times the diameter of the threaded hole, or not more than 2 mm; the thickness of the protective oil film is not less than 2.0 mm.

[0011] Preferably, the high-temperature resistant protective sleeve includes a straight cylinder part for being installed in the pit and an edge part whose bottom surface is used to fit with the surface of the substrate. The edge part is coaxially fixed on the outer wall of the straight cylinder part. The diameter of the edge part is at least 6 mm larger than the diameter of the pit. The thickness of the edge part is 50% of the depth of the pit and not less than 1.5 mm. The inner diameter of the straight cylinder part is equal to the aperture of the threaded hole minus a, where a = 3 - 5 mm.

[0012] Preferably, the high-temperature resistant protective sleeve is made of copper.

[0013] Preferably, in step S2, the laser powder cladding is carried out in a layer-by-layer cladding manner, and wait for 10 minutes - 15 minutes between layers.

[0014] Preferably, the cladding path is to rotate outward in a circumferential direction one by one from the center of the fracture until the inner edge of the high-temperature resistant protective sleeve, and the overlapping area of each circle is 0.5 times the cladding width.

[0015] Preferably, before laying the metal powder, the metal powder needs to be placed in an oven at a temperature of 120°C - 150°C and dried for 90 minutes - 120 minutes, and stirred evenly.

[0016] Preferably, it includes step S4 of removing the oxide formed on the surface of the matrix around the threaded hole due to laser powder cladding and cleaning the threaded hole and the surface of the matrix around the threaded hole.

[0017] Also disclosed is a bolt removal assembly broken in a matrix, including a protective oil film formed by high-temperature-resistant lubricating oil. The protective oil film includes an edge area, a peripheral area, and a filling area. The edge area covers the edge of the pit formed by the threaded hole on the matrix and the fracture surface of the residual bolt. The peripheral area covers the matrix around the pit. The filling area fills the threaded gap between the residual bolt and the threaded hole. A high-temperature-resistant protective sleeve capable of covering the edge area is embedded in the pit. On the flat stacking layer welded on the fracture surface by laser powder cladding in the high-temperature-resistant protective sleeve, the flat stacking layer is flush with the top end of the high-temperature-resistant protective sleeve. A clamping end formed by wire feeding surfacing is welded on the flat stacking layer, and a clamping plane for a clamping tool to clamp is provided on the clamping end.

[0018] The present invention has achieved the following technical effects compared with the prior art:

[0019] 1. The present invention mainly adopts three steps of protecting the thread with high-temperature-resistant lubricating oil, laser powder cladding, and reconstructing the clamping by wire feeding surfacing. First, a flat stacking layer is formed by laser cladding, and then the fracture surface of the bolt is built up by wire feeding surfacing to basically restore the clamping end of the bolt, facilitating the clamping tool to withdraw the residual bolt. The removal work will not generate large mechanical vibrations and avoid damage to the threaded hole. The reason for forming the flat stacking layer by laser cladding first is that through statistical analysis, it can be found that the fracture surface of the broken bolt usually sinks 2-4 mm below the surface of the matrix, forming fracture pits with different depths. The threaded diameter is small and the operating space is smaller. The processability of traditional welding is limited, and it is easy to weld to the threaded hole of the matrix during the welding process, resulting in damage to the thread. However, using laser powder cladding can accurately control the welding range. However, since high temperature and molten metal are generated during the laser cladding process, it will damage the threaded hole. In order to protect the threaded hole and the nearby matrix metal, high-temperature-resistant lubricating oil needs to be used to protect the threaded hole in the early stage. The lubricating oil is evenly coated on the gap between the residual bolt and the matrix and the surface of the matrix to form siltation at the gap, on the surface of the matrix, and in the threaded gap, forming a protective oil film to avoid thermal damage caused by laser cladding.

[0020] 2. The present invention can be extended to the bolt - connected structures in aircraft manufacturing, and can also be extended to the field of mechanical connections in other industries, for quickly removing the residual bolts remaining in the matrix after breakage. In particular, it is applicable to the major overhauls during the service process of various aircraft. In the ground drop tests of aircraft, a considerable number of residual bolts of dummy parts break and remain. By using this patented invention, the residual bolts can be removed in any area including the wild, saving the time and process of returning to the factory for repair, simplifying the test process, and improving the test efficiency.

[0021] 3. This patent is also applicable to the removal of bald bolts or bolts with too short clamping ends, avoiding damage to the matrix mechanism or material. During the long - term use of some mechanisms or fasteners, due to corrosion or frequent repeated use, phenomena such as clamping - end failure, groove - off of the clamping groove, or too short clamping ends occur, making it impossible to normally remove the bolts. The method provided by this invention can be used to increase the length of the clamping end and quickly remove the bolts by applying force. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the following - described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 It is a three - dimensional structure schematic diagram of the bolt remaining in the matrix after breakage;

[0024] Figure 2 It is a cross - sectional structure schematic diagram of the bolt remaining in the matrix after breakage;

[0025] Figure 3 It is a three - dimensional structure schematic diagram of the bolt in the matrix after applying lubricating oil;

[0026] Figure 4 It is a cross - sectional structure schematic diagram of the bolt in the matrix after applying lubricating oil;

[0027] Figure 5 It is a three - dimensional structure schematic diagram of the high - temperature resistant protective sleeve;

[0028] Figure 6 It is a cross - sectional structure schematic diagram of the high - temperature resistant protective sleeve;

[0029] Figure 7 It is a three - dimensional structure schematic diagram of the bolt in the matrix after installing the high - temperature resistant protective sleeve;

[0030] Figure 8 It is a cross - sectional structure schematic diagram of the bolt in the matrix after installing the high - temperature resistant protective sleeve;

[0031] Figure 9 Schematic three-dimensional structure diagram of the bolt inside the substrate after laying metal powder;

[0032] Figure 10 Schematic cross-sectional structure diagram of the bolt inside the substrate after laying metal powder;

[0033] Figure 11 Schematic three-dimensional structure diagram of the bolt inside the substrate during the metal powder cladding process;

[0034] Figure 12 Schematic cross-sectional structure diagram of the bolt inside the substrate during the metal powder cladding process;

[0035] Figure 13 Schematic three-dimensional structure diagram of the bolt inside the substrate when the metal powder forms a flat stacking layer;

[0036] Figure 14 Schematic cross-sectional structure diagram of the bolt inside the substrate when the metal powder forms a flat stacking layer;

[0037] Figure 15 Schematic three-dimensional structure diagram of the bolt inside the substrate during the surfacing of the clamping end;

[0038] Figure 16 Schematic cross-sectional structure diagram of the bolt inside the substrate during the surfacing of the clamping end.

[0039] Explanation of reference numerals: 1. Substrate; 2. Remaining bolt; 3. Pit; 4. Thread clearance; 5. Protective oil film; 6. High-temperature resistant protective sleeve; 7. Powder layer; 8. Laser welding torch; 9. Laser beam; 10. Flat stacking layer; 11. Clamping end; 12. Clamping plane. Detailed implementation manners

[0040] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0041] Embodiment 1

[0042] This embodiment provides a method for removing a bolt broken inside a substrate, as Figures 1 to 16 shown, including the following steps:

[0043] S1. Coat the pit 3 composed of the threaded hole and the fracture surface of the residual bolt 2 with high-temperature resistant lubricating oil to form an annular protective oil film 5. The lubricating oil is preferably high-temperature resistant grease. The outer ring of the protective oil film 5 extends to the surface of the base body 1 outside the pit 3, and the inner ring of the protective oil film 5 extends to the edge of the fracture surface of the residual bolt 2, so that the protective oil film 5 can cover the thread gap 4 between the residual bolt 2 and the threaded hole. Since the lubricating oil has excellent fluidity, the lubricating oil can continue to seep down and fill into the thread gap 4, increasing the protection depth for the threads.

[0044] S2. Install a high-temperature resistant protective sleeve 6 in the pit 3. The outer circle of the high-temperature resistant protective sleeve 6 is in close contact with the inner surface of the threaded hole, and the inner circle of the high-temperature resistant protective sleeve 6 is at least flush with the edge of the protective oil film 5 at the fracture surface, so as to be able to cover the protective oil film 5 at the fracture surface edge. When installing the high-temperature resistant protective sleeve 6, the lubricating oil can be squeezed into the thread gap 4. Use the laser powder cladding method to increase the height of the fracture surface inside the high-temperature resistant protective sleeve 6 until a flush stacking layer 10 flush with the top surface of the high-temperature resistant protective sleeve 6 is formed.

[0045] S3. Use the wire feeding surfacing method to form a clamping end 11 on the flush stacking layer 10, and make a clamping plane 12 for the clamping tool to clamp on the top of the clamping end 11. Use the clamping tool to remove the residual bolt 2. The clamping tool can be a torque wrench. Clamp the clamping plane 12 of the clamping end 11 from both sides, and then slowly, continuously and evenly apply the unloading torque to remove the residual bolt 2. When the bolt is completely removed, the previously placed high-temperature resistant protective sleeve 6 is also removed.

[0046] The lubricating oil can protect the threads and prevent the threads from deforming due to the high temperature brought by laser cladding, ensuring that the threads of the threaded hole and the periphery of the threaded hole are not damaged. The method of piling up the bolt cross-section and reconstructing the clamping end by wire feeding surfacing will not cause mechanical disturbance, and thus can not damage the original threaded hole, remove the residual bolt on the false part, and only replace the new bolt to achieve the purpose of reusing the false part.

[0047] In this embodiment, as Figures 1 to 16 shown, before step S1, it includes step S0 of cleaning the fracture surface and the surface of the base body 1 outside the pit 3, and the fracture surface needs to be smoothed during the cleaning process.

[0048] The specific steps are as follows:

[0049] First, wipe the surface of the pit 3 and its peripheral matrix 1 with a cotton cloth to ensure that there are no foreign substances such as metal residues in the pit 3 and its peripheral area. It is preferred to use a lint-free cotton cloth, which can ensure that no substances harmful to subsequent welding are left. If a linting or debris-shedding cleaning material is used, it is very likely to cause defects in subsequent welding, and the bolt will break again and cannot be repaired. Then, use a rod milling cutter with a smaller diameter to trim the top surface of the fracture of the remaining bolt 2 to make the top surface of the fracture basically flat, and do not damage the threads during trimming. Then, after trimming, use high-pressure air to clean the inside of the threaded hole. Finally, use a white cotton silk cloth dipped in alcohol to thoroughly clean the inside and the nearby area of the thread until the color of the white cotton silk cloth remains unchanged, ensuring that the fracture and its nearby area are clean and pollution-free.

[0050] In this embodiment, as Figures 1 to 16 shown, the width of the part of the protective oil film 5 located on the surface of the peripheral matrix 1 of the pit 3 is not less than 2 times the diameter D of the threaded hole, and the diameter of the threaded hole is also the diameter of the pit 3. That is to say, the area of the protective oil film 5 located on the surface of the peripheral matrix 1 of the pit 3 needs to be not less than 4 times that of the threaded hole, so as to ensure the protective effect of the protective oil film 5. The width of the protective oil film 5 at the edge of the fracture is 0.025 - 0.1 times the diameter D of the threaded hole, or alternatively, the width of the protective oil film 5 at the edge of the fracture is not more than 2 mm. The reason for requiring the edge of the fracture to be coated with lubricating oil is to ensure that the protective oil film 5 completely covers the thread gap 4 and ensure that the lubricating oil can enter the thread gap 4. Only the width of the edge of the fracture is 0.025 - 0.1 times the diameter D of the threaded hole, which means that 0.475D - 0.4D needs to be reserved in the middle of the fracture, and the center part of the fracture is not coated with lubricating oil to avoid affecting subsequent welding. The thickness of the protective oil film 5 is not less than 2.0 mm to play an effective protective role.

[0051] In this embodiment, as Figures 1 to 16 shown, the high-temperature resistant protective sleeve 6 includes a straight tube part for being embedded in the pit 3 and an edge part with the bottom surface for fitting with the surface of the matrix 1, and the edge part is coaxially fixed on the outer wall of the straight tube part. The diameter of the edge part is at least 6 mm larger than the diameter D of the pit 3. The thickness of the edge part is 50% of the depth H of the pit 3 and not less than 1.5 mm. The inner diameter of the straight tube part is equal to the diameter of the threaded hole D minus a, where a = 3 - 5 mm. Preferably, a = 4 mm to ensure that the high-temperature resistant protective sleeve 6 can completely cover the protective oil film 5 at the edge of the pit 3.

[0052] Furthermore, in this embodiment, as Figures 1 to 16 shown, the high-temperature resistant protective sleeve 6 is made of red copper. Red copper material has high temperature resistance, high strength, and low cost, which is the best choice. Of course, if there are better materials for making it, they can also be selected preferentially. The red copper material preferably uses red copper T1 or T2 material.

[0053] Furthermore, in this embodiment, as Figures 1 to 16 shown, in step S2, during laser powder cladding, the layer-by-layer cladding method is adopted, and a waiting time of 10 to 15 minutes is provided between layers. The interval waiting time is mainly used for the lubricating oil to flow back into the thread gap 4 to continue protecting the threads from thermal damage. When the laser beam 9 heats and melts the top of the residual bolt 2 and the deposited powder 7, due to the effect of heat conduction, the entire residual bolt 2 expands thermally, causing the lubricating oil in the thread gap 4 to be squeezed back into the pit 3. The direct reflection is that the area of the protective oil film 5 increases. The additional 10 - 15 minutes of interval waiting time is for the residual bolt 2 and the base 1 to dissipate heat and cool down to room temperature, so that the lubricating oil can flow back into the thread gap 4 to continue protecting the threads from burning. Preferably, when cladding layer by layer, the thickness of each deposited layer is 0.5 ± 0.1 mm. The metal powder composition of the deposited powder 7 is close to that of the residual bolt 2. The particle size diameter of the metal powder is 15 μm - 45 μm.

[0054] Furthermore, in this embodiment, as Figures 1 to 16 shown, the cladding path rotates outward in a circle-by-circle manner along the circumferential direction from the center of the fracture until the inner edge of the high-temperature protective sleeve 6, and the overlapping area of each circle is 0.5 times the cladding width.

[0055] The specific operation steps are as follows:

[0056] Use a laser welding torch 8 with a long focal length (focal length not less than 300 mm) to deposit the deposited powder 7, so that the metal on the fracture surface of the residual bolt 2 and the metal powder are deposited together. The cladding path rotates outward in a circle-by-circle manner along the circumferential direction from the center of the fracture of the residual bolt 2 until the inner edge of the high-temperature protective sleeve 6. The metal powder melts circle by circle, and the overlapping area of each circle is 0.5 times the cladding width, ensuring that all the metal powder melts and solidifies with the residual bolt 2 to form an integral structure.

[0057] Furthermore, in this embodiment, as Figures 1 to 16 shown, before laying the metal powder, the metal powder needs to be dried in an oven at a temperature of 120°C - 150°C for 90 - 120 minutes and stirred evenly.

[0058] In this embodiment, as Figures 1 to 16As shown, when adding wire for surfacing, the method of manually adding the welding wire is adopted. The diameter of the welding wire is preferably 1.6 mm to 3.0 mm. Using automatic or manual surfacing technology, reasonable welding parameters are selected, and a reasonable walking path is planned. Multiple layers of metal materials are surfacing on the fracture surface to form the clamping end 11. Manual methods such as grinding and filing are used to make parallel clamping planes 12 on the top of the clamping end 11. Specifically, a file or other filing tool is used to clean the loose materials around the clamping end to ensure the material strength of the clamping end 11. According to the clamping size of the torque wrench or other clamping tools, the radial dimension and shape of the clamping end 11 are continuously filed to ensure stable clamping of the clamping tool and not easy to slip. Among them, the height of the clamping plane 12 is not less than 20 mm. The height of the clamping end 11 reaches 2.0 to 3.0 times the diameter of the bolt and is not less than 40 mm.

[0059] In this embodiment, as Figures 1 to 16 shown, it includes step S4 of removing the oxides formed on the surface of the substrate 1 around the threaded hole due to laser powder cladding and cleaning the threaded hole and the surface of the substrate 1 around the threaded hole.

[0060] The specific operation steps are as follows:

[0061] First, use a white silk-like cloth dipped in alcohol to wipe the threaded hole and the nearby area to clean other foreign substances such as high-temperature butter; then, use 400-mesh sandpaper and a thin blade scraper to mechanically clean the threaded hole and its nearby area to remove foreign substances such as oxides and scale formed on the metal surface during the laser processing; then, use high-pressure air to clean the inside of the threaded hole; finally, use a white cotton cloth dipped in acetone to thoroughly clean the inside and the nearby area of the thread until the color of the white cotton cloth remains unchanged, ensuring that it is cleaned, ensuring that the inside of the threaded hole is smooth, without scale, without oil stains and other foreign substances that hinder assembly, meeting the requirements for reuse.

[0062] Embodiment 2

[0063] This embodiment provides a bolt removal assembly broken in the substrate, as Figures 1 to 16As shown in the figure, it includes a protective oil film 5 formed by a high-temperature resistant lubricating oil. The protective oil film 5 includes an edge area, a peripheral area, and a filling area. The edge area covers the edge of the pit 3 formed by the threaded hole on the base body 1 and the fracture of the residual bolt 2. The peripheral area covers the surface of the base body 1 on the periphery of the pit 3. The filling area fills the threaded gap 4 between the residual bolt 2 and the threaded hole. A high-temperature resistant protective sleeve 6 capable of covering the edge area is embedded in the pit 3. On the fracture, a flush stacking layer 10 welded by laser powder cladding is provided inside the high-temperature resistant protective sleeve 6. The flush stacking layer 10 is flush with the top end of the high-temperature resistant protective sleeve 6. A clamping end 11 formed by adding wire surfacing is welded on the flush stacking layer 10. A clamping plane 12 for clamping by a clamping tool is provided on the clamping end 11. Preferably, the clamping plane 12 is located at the top of the clamping end 11. By clamping the clamping plane 12 of the clamping end 11 from both sides with a clamping tool, and then slowly, continuously, and evenly applying an unloading torque to remove the residual bolt 2. When the bolt is completely removed, the high-temperature resistant protective sleeve 6 is also removed.

[0064] Furthermore, in this embodiment, as Figures 1 to 16 shown, the width of the peripheral area is not less than 2 times the diameter D of the threaded hole. That is to say, the area located in the peripheral area needs to be not less than 4 times that of the threaded hole. The width of the edge area is 0.025 - 0.1 times the diameter D of the threaded hole, or the width of the protective oil film 5 at the edge of the fracture is not greater than 2 mm. The thickness of the protective oil film 5 is not less than 2.0 mm.

[0065] In this embodiment, as Figures 1 to 16 shown, the high-temperature resistant protective sleeve 6 includes a straight cylinder part and an edge part. The edge part is coaxially fixed on the outer wall of the straight cylinder part. The straight cylinder part is used for being embedded in the pit 3. The bottom surface of the edge part fits with the surface of the base body 1. The diameter of the edge part is at least 6 mm larger than the diameter D of the pit 3. The thickness of the edge part is 50% of the depth H of the pit 3 and not less than 1.5 mm. The inner diameter of the straight cylinder part is equal to the aperture of the threaded hole D minus a, where a = 3 - 5 mm. Preferably, a = 4 mm to ensure that the high-temperature resistant protective sleeve 6 can completely cover the protective oil film 5 at the edge of the pit 3.

[0066] Furthermore, in this embodiment, as Figures 1 to 16 shown, the high-temperature resistant protective sleeve 6 is made of copper.

[0067] Furthermore, in this embodiment, as Figures 1 to 16 shown, the flush stacking layer 10 is formed by layer-by-layer cladding during laser powder cladding. The specific cladding process can refer to Embodiment 1.

[0068] Furthermore, in this embodiment, as Figures 1 to 16 shown, the height of the clamping end 11 reaches 2.0 - 3.0 times the bolt diameter and is not less than 40 mm. The height of the clamping plane 12 is not less than 20 mm.

[0069] In the present invention, specific examples are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for removing a bolt broken in a matrix, characterized in that, it includes the following steps: S1. Coat the concave pit composed of the threaded hole and the fracture of the residual bolt with high-temperature resistant lubricating oil to form an annular protective oil film. The outer ring of the protective oil film extends to the matrix surface outside the concave pit, and the inner ring of the protective oil film extends to the edge of the fracture of the residual bolt, so that the lubricating oil fills the thread gap between the residual bolt and the threaded hole; S2. Install a high-temperature resistant protective sleeve in the concave pit that can cover the protective oil film at the edge of the fracture, and use the laser powder cladding method to increase the height of the fracture in the high-temperature resistant protective sleeve until a flush stacking layer flush with the top surface of the high-temperature resistant protective sleeve is formed; S3. Form a clamping end on the flush stacking layer by the wire feeding surfacing method, and make a clamping plane at the top of the clamping end for the clamping tool to clamp, and use the clamping tool to remove the residual bolt.

2. A method for removing a bolt broken in a matrix according to claim 1, characterized in that, before step S1, it includes step S0, cleaning the fracture and the matrix surface outside the concave pit, and the fracture needs to be smoothed during the cleaning process.

3. A method for removing a bolt broken in a matrix according to claim 2, characterized in that, the width of the part of the protective oil film on the matrix surface outside the concave pit is not less than 2 times the diameter of the threaded hole; the width of the edge of the fracture is 0.05 - 0.2 times the diameter of the threaded hole, or not more than 2 mm; the thickness of the protective oil film is not less than 2.0 mm.

4. A method for removing a bolt broken in a matrix according to claim 3, characterized in that, the high-temperature resistant protective sleeve includes a straight cylinder part for installing in the concave pit and an edge part whose bottom surface is used to fit with the matrix surface. The edge part is coaxially fixed on the outer wall of the straight cylinder part. The diameter of the edge part is at least 6 mm larger than the diameter of the concave pit. The thickness of the edge part is 50% of the depth of the concave pit and not less than 1.5 mm. The inner diameter of the straight cylinder part is equal to the aperture of the threaded hole minus a, where a = 3 - 5 mm.

5. A method for removing a bolt broken in a matrix according to claim 4, characterized in that, the high-temperature resistant protective sleeve is made of copper.

6. A method for removing a bolt broken in a matrix according to claim 1, characterized in that, in step S2, during laser powder cladding, the layer-by-layer cladding method is adopted, and the waiting time between layers is 10 minutes to 15 minutes.

7. A method for removing a bolt broken in a matrix according to claim 6, characterized in that, the cladding path is to rotate outward in a circumferential direction one by one from the center of the fracture until the inner edge of the high-temperature resistant protective sleeve, and the overlapping area of each circle is 0.5 times the cladding width.

8. A method for removing a bolt broken in a matrix according to claim 7, characterized in that, before laying the metal powder, the metal powder needs to be placed in an oven at a temperature of 120°C to 150°C for drying for 90 minutes to 120 minutes and stirred evenly.

9. A method for removing a bolt broken in a matrix according to claim 1, characterized in that, it includes step S4 of removing the oxide formed on the matrix surface around the threaded hole due to laser powder cladding and cleaning the threaded hole and the matrix surface around the threaded hole.

10. A bolt removal assembly broken in a matrix, characterized in that, it includes a protective oil film formed by high-temperature resistant lubricating oil. The protective oil film includes an edge area, a peripheral area and a filling area. The edge area covers the edge of the pit formed by the threaded hole on the matrix and the fracture of the residual bolt. The peripheral area covers the matrix around the pit. The filling area fills the thread gap between the residual bolt and the threaded hole. A high-temperature resistant protective sleeve capable of covering the edge area is embedded in the pit. A flush stacking layer welded on the fracture by laser powder cladding is arranged in the high-temperature resistant protective sleeve. The flush stacking layer is flush with the top end of the high-temperature resistant protective sleeve. A clamping end formed by wire adding surfacing is welded on the flush stacking layer. A clamping plane for clamping by a clamping tool is arranged on the clamping end.

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