Method for repairing damage of thread with key groove at end part of TC2 sleeve

Abstract

The invention relates to the technical field of part repairing, and particularly discloses a TC2 sleeve end thread damage repairing method which comprises the following steps: finding a thread fracture position on a thin-wall sleeve part to be repaired, and polishing the thread fracture position; carrying out laser remelting on the polished area; the prepared repairing powder is used for conducting laser cladding repairing on the area subjected to laser remelting till the height of the damaged part is higher than the height of the original thread; the thin-wall sleeve part subjected to laser cladding repairing is clamped on a lathe through a turning positioning piece; the turned threads are detected, specifically, shape detection and flaw detection of the threads are included; preparing a test piece, and performing a comparison test. The special turning positioning piece is adopted, and part jumping during turning is avoided. The tensile property of the repaired part reaches 98% or above of that of the undamaged part, and the strength of the part is guaranteed. And after cladding, only threads need to be reprocessed, and the key groove position does not need to be reprocessed, so that the processing amount and the processing difficulty are reduced.

Description

Technical Field

[0001] This invention relates to a repair method, specifically a method for repairing damage to the keyway thread at the end of a TC2 sleeve, belonging to the field of component repair technology. Background Technology

[0002] Titanium alloy thin-walled sleeve parts are widely used in aerospace, marine engineering, and chemical equipment due to their excellent properties such as lightweight, certain strength, non-magnetic properties, and corrosion resistance, serving functions such as fixing, force transmission, and connection. During use, sudden excessive loads can easily cause the end threads of these titanium alloy thin-walled sleeve parts to break, affecting their subsequent use. Current repair methods for titanium alloy threads generally involve turning the entire damaged thread and then using argon arc welding to overlay it. This method leads to severe oxidation and deformation of the thin-walled parts, making subsequent machining difficult and compromising the quality of the repair. Summary of the Invention

[0003] To address the problems in the prior art, this invention provides a method for repairing damage to the keyway thread at the end of a TC2 sleeve.

[0004] The objective of this invention can be achieved through the following technical solutions: A method for repairing damage to the keyway thread at the end of a TC2 sleeve includes the following steps: Step 1: Locate the broken thread on the thin-walled sleeve part to be repaired, and grind the broken thread. Step 2: Laser remelting is performed on the polished area to form a relatively smooth surface; Step 3: Use the prepared repair powder to perform laser cladding repair on the area after laser remelting until the height of the damaged area is higher than the original thread height; Step 4: Using a turning positioning component, clamp the laser-clad repaired thin-walled sleeve part onto a lathe, and turn out the thread based on the existing thread. Step 5: Inspect the machined threads, including thread shape inspection and flaw detection. Step Six: Prepare test pieces and conduct comparative tests to detect the tensile strength of the parts repaired using this repair method.

[0005] Optionally, in step one, a grinder is used to grind the broken thread to remove surface foreign matter until the bright metal color (silver white) is exposed.

[0006] Optionally, the laser remelting in step two specifically involves: a laser power of 400-500 W, a scanning speed of 8-12 mm / s, a protective gas flow rate of 15-20 L / min, a distance of 1 cm between the bottom of the laser cladding head nozzle and the surface of the thin-walled sleeve part, with the thin-walled sleeve part stationary and the laser cladding head moving. A robotic arm drives the laser cladding head along a preset trajectory, which is an arc-shaped trajectory.

[0007] Optionally, the specific composition of the repair powder in step three is as follows: Al: 6~6.5%, V: 4~4.5%; Fe≤0.05%; Si≤0.05%; O≤0.075%; N≤0.02%; H≤0.008%; C≤0.015%, with the balance being Ti; the powder flowability is less than 36s / 50g, and the powder particle size is 53~150μm.

[0008] Optionally, the laser cladding repair process in step three specifically includes: S1: Perform laser cladding repair at a position 0.5-1 mm from the edge of the keyway. The cladding process is single-point cladding, with neither the laser cladding head nor the part moving. The cladding time is 0.3-0.5 s, the powder feeder speed is 0.5~0.8 rpm, the protective gas flow rate is 15~20 L / min, the spot diameter is 1~1.3 mm, and the laser power is 500~600 W. S2: Perform laser cladding repair from the damaged area >2 mm from the edge of the keyway towards the edge of the keyway. The endpoint of the cladding is the single-point cladding position in step S1. The powder feeder speed is 0.5~0.8 rpm, the protective gas flow rate is 15~20 L / min, the spot diameter is 1~1.3 mm, the laser power is 500~700 W, and the robot arm drives the laser cladding head to move along the preset trajectory. The preset trajectory is an arc trajectory, and the bottom of the laser cladding head nozzle is 1 cm away from the surface of the part.

[0009] Optionally, the turning positioning component in step four is made of aluminum alloy and specifically includes a cylindrical section with one end for insertion into the hole of the thin-walled sleeve part. The diameter of the cylindrical section is 0.005~0.016 mm smaller than the inner diameter of the hole of the thin-walled sleeve part. One end of the cylindrical section is connected to a positioning seat, which is frustum-shaped. The end away from the cylindrical section is the large-diameter end, and the center of the large-diameter end of the positioning seat is provided with a center hole for insertion of the lathe center, so as to reduce the runout of the thin-walled sleeve part during the turning process.

[0010] Optionally, the thread shape detection and flaw detection are specifically as follows: Shape inspection: Use a thread ring gauge corresponding to the thread size to test whether the thread shape is qualified. The mating thread ring gauge can be screwed into the thread of the repaired part according to the preset requirements (smooth and without jamming), which means that the thread shape after repair is qualified. If the shape after repair is not qualified, steps one to four can be repeated to perform shape inspection again until the shape is qualified.

[0011] Flaw detection: Perform fluorescent flaw detection on the repaired threaded area. If no cracks are found, the flaw detection is deemed qualified after repair. If the flaw detection fails after repair, repeat steps one to four and the shape detection step to perform flaw detection again until the flaw detection is qualified.

[0012] Optionally, the specific process of the tensile strength test in step six is ​​as follows: Test specimens were prepared using annealed TC2 sheet metal, including repair specimens and control specimens. The repair part was prepared by creating a 50% depth groove in the middle of the annealed TC2 sheet, then performing cladding in step three to fill the groove and prepare a tensile sample; the control part was a tensile sample prepared directly from the annealed TC2 sheet. The tensile strength of the repaired part is compared with that of the control part. If the tensile strength of the repaired part reaches 98% of that of the control part, and the fracture occurs at a location far from the repair area, then the repair method is deemed satisfactory and the repaired part can be used. If the tensile strength after repair does not meet the target, the repair is deemed a failure.

[0013] The beneficial effects of this invention are: 1. Specialized turning positioning components are used to prevent part runout during turning.

[0014] 2. The tensile properties after repair reach more than 98% of those before damage.

[0015] 3. Only the threads need to be re-machined; the keyway position does not need to be re-machined, reducing the amount of machining and the difficulty of machining. Attached Figure Description

[0016] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the structure of the thin-walled sleeve part damaged according to the present invention.

[0018] Figure 2 This is a schematic diagram of the turning positioning component of the present invention.

[0019] Figure 3 This is a schematic diagram of the assembly of the repaired thin-walled sleeve part and the turning positioning part according to the present invention.

[0020] Figure 4 This is a schematic diagram of the beam displacement and stress curves of the repaired part and the control part of the present invention.

[0021] Figure 5 This is a schematic diagram showing the morphology of the repaired part and the control part of the present invention after being broken.

[0022] In the diagram: 1. Thin-walled sleeve part; 2. Thread breakage location; 3. Turned positioning part; 4. Cylindrical section; 5. Ejector pin hole. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please see Figure 1-5 As shown, a method for repairing damage to the keyway thread at the end of a TC2 sleeve includes the following steps: 1. Visually inspect the TC2 thin-walled sleeve part 1 to find the broken thread 2. Use an electric grinder to grind the broken thread 2 to remove surface foreign matter until the bright metal color (silver white) is exposed.

[0025] 2. Laser remelting is performed on the fractured thread at location 2 to create a relatively smooth surface and to heal micro-cracks. The laser power is 450 W, the scanning speed is 10 mm / s, and the protective gas flow rate is 15 L / min. With the part stationary, the robotic arm moves the laser cladding head along an arc-shaped trajectory, always maintaining the bottom of the laser cladding head nozzle 1 cm from the workpiece surface.

[0026] 3. A special repair powder was prepared using an electrode induction melting gas atomization method. The powder composition was: Al: 6.23%, V: 4.1%; Fe: 0.028%; Si: 0.04%; O: 0.072%; N: 0.017%; H: 0.006%; C: 0.012%, with the balance being Ti. The powder flowability was 34.4 s / 50g, and the particle size was 53~150 μm.

[0027] 4. Apply laser cladding to repair powder at a distance of 0.5 mm from the edge of the keyway. This step involves fine cladding repair on a small area on both sides of the keyway to avoid affecting the keyway. The cladding process is a single-point cladding, with neither the laser cladding head nor the workpiece moving. The cladding time is 0.4 s, the powder feeder speed is 0.5 rpm, the protective gas flow rate is 20 L / min, the spot diameter is 1.2 mm, and the laser power is 500 W.

[0028] 5. Begin laser cladding from the damaged area 10 mm from the keyway edge towards the keyway edge, with the cladding endpoint at the single-point cladding position from step 4. The cladding trajectory can be set at this point, proceeding from the starting point towards both sides of the keyway to ensure uniform and thorough repair of the damaged area across the entire part. The powder feeder speed is 0.6 rpm, the protective gas flow rate is 20 L / min, the spot diameter is 1 mm, the laser power is 600 W, and the robotic arm drives the laser cladding head in an arc-shaped trajectory, always maintaining the bottom of the laser cladding head nozzle 1 cm from the workpiece surface.

[0029] 6. Repeat steps 4 and 5 until the height of the damaged area repaired by laser cladding is higher than the original thread height.

[0030] 7. Machining and positioning part 3, which includes cylindrical section 4, positioning seat and ejector pin hole 5. The diameter of cylindrical section 4 is 0.01 mm smaller than the inner diameter of hole 1 of TC2 thin-walled sleeve part 1. The machining and positioning part 3 is made of aluminum alloy.

[0031] 8. Mount the laser-clad repaired TC2 thin-walled sleeve part 1 onto a lathe. Insert the cylindrical section 4 of the turning positioning part 3 into the threaded end of the TC2 thin-walled sleeve part 1. Place the lathe's center pin in the center pin hole 5 of the positioning seat to reduce the runout of the thin-walled sleeve part 1 during turning and improve accuracy. Using the existing thread as a reference, turn the thread.

[0032] 9. Use a thread ring gauge corresponding to the thread size to test whether the thread shape is qualified. If the mating thread ring gauge can be smoothly screwed into the thread of the repaired part, the shape after repair is determined to be qualified.

[0033] 10. Fluorescent flaw detection was performed on the repaired threaded area, and no cracks were found. The flaw detection was deemed qualified after repair.

[0034] 11. Test specimens were prepared using annealed TC2 sheet metal, including repaired and control specimens. The repaired specimen was prepared by creating a 50% depth groove in the center of the annealed TC2 sheet metal, followed by cladding in step 5 to fill the groove, thus preparing a tensile specimen. The control specimen was prepared directly from the annealed TC2 sheet metal. The performance of the repaired and control specimens was compared. The tensile strengths of the control specimen were 802 MPa, 800 MPa, and 812 MPa, with an average of 804.7 MPa. The tensile strengths of the repaired specimen were 800 MPa, 801 MPa, and 794 MPa, with an average of 798.3 MPa. The tensile strength of the repaired specimen reached 99.2% of that of the control specimen, and fracture occurred far from the repair area. Therefore, the repaired specimen was deemed to have passed the performance test and was usable.

[0035] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for repairing damage to the keyway thread at the end of a TC2 sleeve, characterized in that, Includes the following steps: Step 1: Locate the broken thread on the thin-walled sleeve part to be repaired, and grind the broken thread. Step 2: Laser remelting of the polished area; Step 3: Use the prepared repair powder to perform laser cladding repair on the area after laser remelting until the height of the damaged area is higher than the original thread height; Step 4: Using a turning positioning component, clamp the laser-clad repaired thin-walled sleeve part onto a lathe and turn out the threads; Step 5: Inspect the machined threads, including thread shape inspection and flaw detection. Step Six: Prepare test pieces and conduct comparative tests to detect the tensile strength of the parts repaired using this repair method.

2. The method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, In step one, a grinder is used to grind the broken screw thread to remove surface foreign matter until the bright metal color is exposed.

3. The method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, The laser remelting in step two is specifically as follows: laser power 400~500 W, scanning speed 8~12 mm / s, protective gas flow rate 15~20 L / min, the bottom of the laser cladding head nozzle is 1 cm away from the surface of the thin-walled sleeve part, the thin-walled sleeve part remains stationary, and the laser cladding head moves.

4. The method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, The specific composition of the repair powder in step three is as follows: Al: 6~6.5%, V: 4~4.5%; Fe≤0.05%; Si≤0.05%; O≤0.075%; N≤0.02%; H≤0.008%; C≤0.015%, with the balance being Ti; the powder flowability is less than 36s / 50g, and the powder particle size is 53~150μm.

5. A method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, The laser cladding repair process in step three specifically includes: S1: Perform laser cladding repair at a distance of 0.5-1 mm from the edge of the keyway. The cladding process is a single-point cladding, with neither the laser cladding head nor the part moving. The cladding time is 0.3-0.5 s, the powder feeder speed is 0.5~0.8 rpm, the protective gas flow rate is 15~20 L / min, the spot diameter is 1~1.3 mm, and the laser power is 500~600 W. S2: Perform laser cladding repair from the damaged area >2 mm from the edge of the keyway towards the edge of the keyway. The endpoint of the cladding is the single-point cladding position in step S1. The powder feeder speed is 0.5~0.8 rpm, the protective gas flow rate is 15~20 L / min, the spot diameter is 1~1.3 mm, the laser power is 500~700 W, the laser cladding head moves along the preset trajectory, and the bottom of the laser cladding head nozzle is 1 cm away from the surface of the part.

6. A method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, In step four, the turning positioning component is made of aluminum alloy and specifically includes a cylindrical section with one end for insertion into the hole of the thin-walled sleeve part. The diameter of the cylindrical section is 0.005~0.016 mm smaller than the inner diameter of the hole of the thin-walled sleeve part. One end of the cylindrical section is connected to a positioning seat, which is frustum-shaped. The end away from the cylindrical section is the large-diameter end, and the center of the large-diameter end of the positioning seat is provided with a center hole for insertion of the lathe center.

7. A method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, The specific details of the thread shape detection and flaw detection are as follows: Shape inspection: Use a thread ring gauge corresponding to the thread size to test whether the thread shape is qualified. The mating thread ring gauge can be screwed into the thread of the repaired part according to the preset requirements, which means that the thread shape after repair is qualified. Flaw detection: Fluorescent flaw detection is performed on the repaired threaded parts. If no cracks are found, the repair is deemed to be qualified.

8. A method for repairing damage to the keyway thread at the end of a TC2 sleeve according to claim 1, characterized in that, The specific process of the tensile strength test in step six is ​​as follows: Test specimens were prepared using annealed TC2 sheet metal, including repair specimens and control specimens. The repair part was prepared by creating a 50% depth groove in the middle of the annealed TC2 sheet, then performing cladding in step three to fill the groove and prepare a tensile sample; the control part was a tensile sample prepared directly from the annealed TC2 sheet. The tensile strength of the repaired part is compared with that of the control part. If the tensile strength of the repaired part reaches 98% of that of the control part and the fracture occurs at a location far from the repair area, then the performance of the repaired part is deemed qualified and the repaired part can be used.

Images