Method for repairing superficial corrosion damage of groove in 30CrMnSiNi2A sleeve part

Abstract

The invention discloses a method for repairing superficial corrosion damage of an inner groove of a 30CrMnSiNi2A sleeve part. The method comprises the following steps that S1, the corrosion damage condition and position of the inner groove of a sleeve are determined; s2, the corrosion damage part of the inner groove is polished; s3, preparing a protection sheet, wherein the protection sheet is U-shaped, and a notch is formed in the bottom wall or the side wall of the protection sheet; s4, preparing an electrode bar; s5, the protection piece is magnetically attracted into the inner groove, and the groove opening corresponds to the corrosion damage part; the electrode bar is installed on an ultrasonic vibration electric spark repairing machine to conduct surfacing repairing on the corrosion damage part; s6, the micro welding gun is installed on a cold welding machine, and cold welding remelting is conducted on the surfacing repairing layer; s7, the operation of the step S5 and the operation of the step S6 are repeated for multiple times till the damage repairing position is higher than the original groove wall face of the inner groove; s8, the sleeve is fixed to a boring machine, and the inner groove is machined again through a small-aperture boring cutter; and S9, preparing a test piece to verify the corrosion damage repair effect. The method solves the problem that at present, repairing of superficial corrosion damage of the groove in the 30CrMnSiNi2A sleeve part is difficult.

Description

Technical Field

[0001] This invention relates to the field of remanufacturing technology, and more specifically to a method for repairing shallow corrosion damage in the inner grooves of 30CrMnSiNi2A sleeve parts. Background Technology

[0002] 30CrMnSiNi2A is a typical low-alloy ultra-high-strength steel with advantages such as high strength, good plasticity and toughness. It is used to manufacture important load-bearing structural components such as high-strength connectors, shaft parts, and sleeve parts.

[0003] The sleeve in a hydraulic cylinder is one of the core components, primarily responsible for structural support and guidance, pressure bearing, and sealing. Some sleeve parts have internal grooves to accommodate sealing rings and improve sealing performance. After prolonged use, corrosion can occur in the internal grooves due to chemical corrosion or external moisture and salt spray intrusion, leading to hydraulic system leaks, pressure drops, and even component failure.

[0004] Due to the limited space in the grooves inside the sleeve, existing repair methods such as laser cladding and welding have poor accessibility and are difficult to complete the repair of the sleeve.

[0005] Therefore, how to provide a method for repairing shallow corrosion damage in the inner grooves of 30CrMnSiNi2A sleeve parts is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method for repairing shallow corrosion damage in the inner grooves of 30CrMnSiNi2A sleeve parts, which solves the current problem of difficult repair of shallow corrosion damage in the inner grooves of 30CrMnSiNi2A sleeve parts.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A method for repairing shallow corrosion damage in the inner grooves of a 30CrMnSiNi2A sleeve part includes the following steps: S1. Determine the extent and location of corrosion damage in the inner grooves of the sleeve; S2. Grind the corroded and damaged parts of the inner groove using a suspended grinder; S3. Prepare a protective sheet, wherein the protective sheet is U-shaped and the bottom or side wall of the concave cavity of the protective sheet is provided with a groove; the protective sheet is adapted to the shape of the inner groove; S4. Prepare electrode rods; S5. Magnetically attach the protective sheet to the inner groove and align the groove opening with the corrosion-damaged area; install the electrode rod on the ultrasonic vibration EDM repair machine and weld the corrosion-damaged area through the groove opening for repair. S6. Remove the protective sheet, install the mini welding gun on the cold welding machine, and use the mini welding gun to cold weld and remelt the weld overlay repair layer; S7. Repeat steps S5 and S6 multiple times until the damaged repair position is higher than the original groove wall surface. S8. Fix the sleeve on the boring machine and use a small-diameter boring tool to further machine the inner groove; S9. Prepare test specimens to verify the effect of corrosion damage repair.

[0008] Preferably, in step S1, an industrial endoscope is used to observe the damage to the inner groove of the sleeve to determine whether the corrosion damage is located on the bottom wall or the side wall of the inner groove.

[0009] Preferably, in step S2, the elbow handle is installed on the grinding machine according to the location of corrosion damage, and the bottom wall or side wall of the inner groove is ground until the corrosion pit is removed.

[0010] Preferably, in step S3, a groove is provided on the bottom surface of the protective sheet to correspond to corrosion damage to the bottom wall of the inner groove; and a groove is provided on the side wall of the protective sheet to correspond to corrosion damage to the side wall of the inner groove.

[0011] Preferably, in step S4, the electrode rod is prepared using A-100 steel bar material; one end of the electrode rod is the connecting end and the other end is the weld overlay end. When the corrosion damage occurs on the bottom wall of the inner groove, the angle between the weld overlay end and the connecting end is 90°. When the corrosion damage occurs on the side wall of the inner groove, the angle between the weld overlay end and the connecting end is 100°~135° or 45°~80°.

[0012] Preferably, during the welding repair and cold welding remelting process, an argon gas delivery pipeline is inserted from the end of the sleeve away from the inner groove, and the outlet of the argon gas delivery pipeline corresponds to the groove opening.

[0013] Preferably, in step S6, the ceramic nozzle of the micro welding gun is detachably connected to a tungsten needle, and the weld repair position is cold-welded and remelted through the tungsten needle (61); during the cold welding process, the pulse current of the micro welding gun is 130~200 A and the pulse time is 130~200 ms.

[0014] Preferably, in step S9, the test piece material is 30CrMnSiNi2A material. The test piece undergoes the same heat treatment process as the sleeve. A defect with a depth of 0.2mm is machined on the surface of the test piece. Steps S5 and S6 are used for repair. The cross-sectional structure of the test piece after repair is observed and the microhardness is tested. If the surface hardness of the repaired area of ​​the test piece reaches 95% of the hardness of the substrate and there are no cracks in the repaired area, the sleeve is considered to be successfully repaired.

[0015] Preferably, during the welding repair process, the current of the ultrasonic vibration electrical discharge repair machine is 50~70 A, the pulse current frequency is 1000~1200 Hz, and the ultrasonic vibration frequency is 25000~30000 Hz.

[0016] Preferably, the electrode rod has a radius of r, a length of h1 before welding, and a length of h2 after welding. Therefore, the volume consumed by the electrode rod is V1 = πr. 2 (h1-h2); The groove area of ​​the protective sheet is S. Based on the principle that the volume consumed by the electrode rod is equal to the volume increased at the weld, the thickness of the weld repair area is d=πr. 2 (h1-h2) / S, controlling the thickness of the weld overlay repair area to be less than 0.5mm during a single repair.

[0017] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a method for repairing shallow corrosion damage in the inner groove of 30CrMnSiNi2A sleeve parts, which overcomes the problem that the accessibility of corrosion damage repair in the inner groove of 30CrMnSiNi2A sleeve parts is poor due to the limited space. The mechanical properties and hardness properties of the sleeve after repair using this method meet the requirements, and the sleeve is free from defects such as undercut after repair, and the dimensions meet the requirements. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the sleeve groove bottom wall overlay repair structure provided by the present invention; Figure 2 This is a schematic diagram of the sleeve groove sidewall overlay repair structure provided by the present invention; Figure 3 This is a schematic diagram of the electrode rod structure provided by the present invention; Figure 4 A schematic diagram of the remelting structure of the bottom wall of the sleeve groove provided by the present invention; Figure 5 A schematic diagram of the remelted sidewall structure of the sleeve groove provided by the present invention; Figure 6 A schematic diagram of the micro welding torch structure for remelting the bottom wall of the sleeve groove provided by the present invention; Figure 7 A schematic diagram of the micro welding torch structure for remelting the sidewall of the sleeve groove provided by the present invention; Figure 8This invention provides a schematic diagram of the grooved sidewall of the internal protective sheet; Figure 9 This is a schematic diagram of the grooved bottom wall of the protective sheet provided by the present invention.

[0020] Among them, 1-sleeve; 2-inner groove; 3-protective plate; 31-groove opening; 4-electrode rod; 41-welding end; 5-argon gas delivery pipeline; 6-miniature welding torch; 61-tungsten needle. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0022] Participate in the attached Figure 1 Up to 9, embodiments of the present invention disclose a method for repairing shallow corrosion damage in the inner grooves of 30CrMnSiNi2A sleeve parts, which solves the current problem of difficult repair of shallow corrosion damage in the inner grooves of 30CrMnSiNi2A sleeve parts, including the following steps: S1. Determine the corrosion damage and location of the inner groove 2 of sleeve 1; specifically, use an industrial endoscope to observe the damage of the inner groove 2 of sleeve 1 and determine whether the corrosion damage is located on the bottom wall or the side wall of the inner groove 2.

[0023] S2. Grind the corroded and damaged parts of the inner groove 2 using a hanging grinder. Depending on the location of the corrosion damage, install the elbow handle on the hanging grinder and grind the bottom wall or side wall of the inner groove 2 to remove corrosion products. Grind until the corrosion pits are cleared.

[0024] S3. Prepare a protective sheet 3. The protective sheet 3 is U-shaped and the bottom wall or side wall of the cavity of the protective sheet 3 is provided with a groove 31. The protective sheet 3 is adapted to the shape of the inner groove 2. Corresponding to the corrosion damage of the bottom wall of the inner groove 2, the bottom surface of the protective sheet 3 is provided with a groove 31. Corresponding to the corrosion damage of the side wall of the inner groove 2, the side wall of the protective sheet 3 is provided with a groove 31.

[0025] S4. Prepare electrode rod 4; A-100 steel (23Co14Ni12Cr3MoE steel) rod is wire-cut into φ1.5~3 mm rods, the surface oxide scale is manually ground off, and the end is bent to form electrode rod (4); one end of electrode rod 4 is the connecting end, and the other end is the weld overlay end 41. When the corrosion damage occurs on the bottom wall of the inner groove 2, the angle between the weld overlay end 41 and the connecting end is 90°. When the corrosion damage occurs on the side wall of the inner groove 2, the angle between the weld overlay end 41 and the connecting end is 100°~135° (corresponding to the side wall of the inner groove away from the sleeve, i.e., the far side wall of the inner groove) or 45°~80° (corresponding to the near side wall of the inner groove).

[0026] S5. Magnetically attach the protective sheet 3 into the inner groove 2 and make the groove opening 31 correspond to the corrosion-damaged area; install the electrode rod 4 on the ultrasonic vibration electric spark repair machine, and perform weld repair on the corrosion-damaged area through the groove opening 31.

[0027] like Figure 8 and 9 As shown, the protective plate 3 is U-shaped, with magnetic pieces extending outward from both ends of its opening. These magnetic pieces magnetically attract the protective plate 3 to the top wall of the inner groove 2. The U-shaped shape of the protective plate 3 fits the inner cavity of the inner groove 2. When corrosion damage occurs to the bottom wall of the inner groove 2, a protective plate 3 with a slot 31 at the bottom is selected. When corrosion damage occurs to the side wall of the inner groove 2, a protective plate with a slot 31 on the side wall is selected. The corroded area in the inner groove 2 of the sleeve 1 can be exposed through the slot 31. Figure 1 As shown in Figure 3, for damage to the bottom wall of the inner groove 2, a motor rod 4 with a 90° angle between the weld overlay end 41 and the connecting end is used for weld overlay repair; for the damage to the far side wall of the inner groove 2 (according to...) Figure 2 The right sidewall of the inner groove 2 (in the direction shown) suffered corrosion damage and was repaired by welding with a motor rod 4 at an angle of 100° to 135° between the weld overlay end 41 and the connecting end; for the near-end sidewall of the inner groove 2 (according to...) Figure 2 Corrosion damage occurred on the left side of the tank wall (as shown in the direction), and the motor rod 4 with a 45° ~ 80° angle between the weld overlay end 41 and the connection end was used for weld overlay repair.

[0028] To further optimize the above technical solution, during the welding repair process, the current of the ultrasonic vibration electrical discharge repair machine is 50~70 A, the pulse current frequency is 1000~1200 Hz, and the ultrasonic vibration frequency is 25000~30000 Hz.

[0029] In this embodiment, the radius of electrode rod 4 is r, the length of electrode rod 4 before welding is h1, and the length after welding is h2. Therefore, the volume consumed by electrode rod 4 is V1 = πr. 2(h1-h2); The area of ​​the groove 31 of the protective sheet 3 is S. According to the principle that the volume consumed by the electrode rod 4 is equal to the volume increased at the weld, the thickness of the weld repair area is d=πr. 2 (h1-h2) / S, controlling the thickness d of the weld overlay repair area to be less than 0.5mm during a single repair.

[0030] S6. Remove the protective plate 3, install the miniature welding torch 6 on the cold welding machine, and perform cold welding remelting on the weld overlay repair layer using the miniature welding torch 6. The ceramic nozzle of the miniature welding torch 6 is detachably connected to a tungsten needle 61, which is used to perform cold welding remelting on the weld overlay repair area; such as... Figure 5 and 7 As shown, tungsten needle 61 is a right-angled tungsten needle, used for cold welding remelting operations where corrosion damage occurs on the sidewall of the inner groove 2; as Figure 4 and 6 The tungsten needle 61 is a straight tungsten needle, used for cold welding and remelting operations when the bottom wall of the inner groove 2 is corroded.

[0031] To further optimize the above technical solution, during the cold welding process, the pulse current of the miniature welding torch 6 is 130~200 A and the pulse time is 130~200 ms.

[0032] To further optimize the above technical solution, during the cold welding and remelting process, the tungsten needle 61 extends at least 18mm beyond the ceramic nozzle, so that the tungsten needle 61 can reach the repair site of the inner groove 2 while leaving space for observation.

[0033] To further optimize the above technical solution, during the welding repair and cold welding remelting process, an argon gas delivery pipeline 5 extends from the end of the sleeve 1 away from the inner groove 2, and the outlet of the argon gas delivery pipeline 5 corresponds to the groove 31. The argon gas delivery pipeline 5 has two outlets, which do not occupy the space of the groove 31 and can obtain good argon gas protection during the welding repair process.

[0034] S7. Repeat steps S5 and S6 multiple times until the damaged repair position is higher than the original groove wall of the inner groove 2.

[0035] S8. Fix the sleeve 1 on the boring machine and use a small-diameter boring tool to further process the inner groove 2; use the small-diameter boring tool to grind the weld overlay and remelting area of ​​the inner groove 2 to make it reach the specified size.

[0036] S9. Prepare test specimens to verify the effect of corrosion damage repair.

[0037] The test piece is made of 30CrMnSiNi2A material. The test piece undergoes the same heat treatment process as sleeve 1. A defect with a depth of 0.2mm is machined on the surface of the test piece. Steps S5 and S6 are used for repair. The cross-sectional structure of the test piece after repair is observed and the microhardness is tested. If the surface hardness of the repaired area of ​​the test piece reaches 95% of the hardness of the base material and there are no cracks in the repaired area, then sleeve 1 is judged to have been successfully repaired.

[0038] In this embodiment, externally inclined electrode rods (with an angle of 100° to 135° between the welded end and the connecting end), vertically inclined electrode rods (with an angle of 90° between the welded end and the connecting end), and internally inclined electrode rods (with an angle of 45° to 80° between the welded end 41 and the connecting end) were prepared and installed on an ultrasonic vibration EDM repair machine to perform weld repair on defects on the left, bottom, and right walls of the inner groove of the sleeve. The ultrasonic vibration electrical discharge repair process uses a protective sheet to control the repair area. The thickness of the repair area can be calculated by the principle that the volume consumed by the electrode rod is equal to the volume increased at the weld. This effectively controls the area and thickness of the electrical discharge welding repair and solves the bottleneck problem of difficulty in measuring the thickness of the repair area in the inner groove.

[0039] During the cold welding remelting process, the pulse current of the miniature welding gun is 130~200 A and the pulse time is 130~200 ms, so that the melting depth of the welding area reaches more than 0.8 mm. It can simultaneously remelt the electric spark weld area (thickness less than 0.5 mm) along with the sleeve substrate, ensuring that there are no cracks in the area after cold welding.

[0040] Extend the tungsten needle on the miniature welding torch of the cold welding machine at least 1.8cm beyond the ceramic nozzle. When cold welding the left and right walls, the tungsten needle on the welding torch should be bent to ensure that the tungsten needle is perpendicular to the left or right wall. Use special argon gas protection to deal with the repair of complex spaces and ensure the repair quality.

[0041] Electrode rods were prepared using A-100 steel (23Co14Ni12Cr3MoE steel) bars, ensuring that the hardness of the repaired area could reach 95% of that of the substrate after repair.

[0042] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0043] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for repairing shallow corrosion damage in the inner grooves of a 30CrMnSiNi2A sleeve part, characterized in that, Includes the following steps: S1. Determine the corrosion damage and location of the inner groove (2) of the sleeve (1); S2. Grind the corroded and damaged parts of the inner groove (2) using a grinding machine; S3. Prepare a protective sheet (3). The protective sheet (3) is U-shaped and the bottom wall or side wall of the cavity of the protective sheet (3) is provided with a groove (31). The protective sheet (3) is adapted to the shape of the inner groove (2). S4. Prepare electrode rods (4); S5. Magnetically attach the protective sheet (3) into the inner groove (2) and make the groove opening (31) correspond to the corrosion damage area; install the electrode rod (4) on the ultrasonic vibration electric spark repair machine, and perform weld repair on the corrosion damage area through the groove opening (31); S6. Remove the protective sheet (3), install the miniature welding gun (6) on the cold welding machine, and cold weld and remelt the weld overlay repair layer through the miniature welding gun (6); S7. Repeat steps S5 and S6 multiple times until the damaged repair position is higher than the original groove wall of the inner groove (2). S8. Fix the sleeve (1) on the boring machine and use a small-diameter boring tool to re-machine the inner groove (2); S9. Prepare test specimens to verify the effect of corrosion damage repair.

2. The method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 1, characterized in that, In step S1, an industrial endoscope is used to observe the damage to the inner groove (2) of the sleeve (1) to determine whether the corrosion damage is on the bottom wall or the side wall of the inner groove (2).

3. The method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 2, characterized in that, In step S2, according to the location of corrosion damage, the elbow handle is installed on the hoisting grinder and the bottom wall or side wall of the inner groove (2) is ground until the corrosion pit is removed.

4. The method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 3, characterized in that, In step S3, for corrosion damage to the bottom wall of the inner groove (2), a groove (31) is provided on the bottom surface of the protective plate (3); for corrosion damage to the side wall of the inner groove (2), a groove (31) is provided on the side wall of the protective plate (3).

5. A method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 4, characterized in that, In step S4, electrode rod (4) is prepared using A-100 steel bar material; one end of electrode rod (4) is the connecting end and the other end is the weld overlay end (41). When the corrosion damage occurs on the bottom wall of the inner groove (2), the angle between the weld overlay end (41) and the connecting end is 90°. When the corrosion damage occurs on the side wall of the inner groove (2), the angle between the weld overlay end (41) and the connecting end is 100° ~ 135° or 45° ~ 80°.

6. The method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 5, characterized in that, During the overlay repair and cold welding remelting process, an argon gas delivery pipeline (5) is inserted from the end of the sleeve (1) away from the inner groove (2), and the outlet of the argon gas delivery pipeline (5) corresponds to the groove (31).

7. A method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 6, characterized in that, In step S6, the ceramic nozzle of the micro welding gun (6) is detachably connected to a tungsten needle (61), and the weld repair position is cold welded and remelted through the tungsten needle (61); during the cold welding process, the pulse current of the micro welding gun (6) is 130~200 A and the pulse time is 130~200 ms.

8. The method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 7, characterized in that, In step S9, the test piece material is 30CrMnSiNi2A material. The test piece undergoes the same heat treatment process as the sleeve (1). A defect with a depth of 0.2mm is machined on the surface of the test piece. Steps S5 and S6 are used for repair. The cross-sectional structure of the test piece after repair is observed and the microhardness is tested. If the surface hardness of the repair area of ​​the test piece reaches 95% of the hardness of the substrate and there are no crack defects in the repair area, the sleeve (1) is judged to be successfully repaired.

9. A method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 1, characterized in that, During the welding repair process, the current of the ultrasonic vibration EDM repair machine is 50~70 A, the pulse current frequency is 1000~1200 Hz, and the ultrasonic vibration frequency is 25000~30000 Hz.

10. A method for repairing shallow corrosion damage in the inner groove of a 30CrMnSiNi2A sleeve part according to claim 1, characterized in that, The radius of the electrode rod (4) is r, the length of the electrode rod (4) before welding is h1, and the length after welding is h2. Then the volume consumed by the electrode rod (4) is V1 = πr. 2 (h1-h2); The area of ​​the groove (31) of the protective sheet (3) is S. According to the principle that the volume consumed by the electrode rod (4) is equal to the volume increased at the weld, the thickness of the weld repair area is d=πr. 2 (h1-h2) / S, controlling the thickness of the weld overlay repair area to be less than 0.5mm during a single repair.

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