Method for repairing babbitt metal layer of bearing bush for rotary machinery

Abstract

The invention discloses a method for repairing a babbitt metal layer of a bearing bush for rotary machinery, which comprises the following steps of: firstly, carrying out nondestructive testing on a bearing bush body, and accurately marking a to-be-repaired area; then the to-be-repaired area is mechanically polished, and the babbitt metal layer of the to-be-repaired area is removed; then carrying out nondestructive testing on the area near the to-be-repaired area again to confirm that the babbitt metal layer has no defect display; then selecting babbitt metal powder of a corresponding mark and drying the babbitt metal powder; then, the dried babbitt metal powder is used as a raw material for cold spraying repair; then programming a spray gun path based on the geometrical shape of the repair area, and finishing coating coverage after trial spraying; then the quality of a bonding interface is rechecked through ultrasonic waves, and it is guaranteed that the repairing area and the base body are well bonded and do not have the standard exceeding defect; afterwards, finish machining is conducted on the allowance of the surface of the new babbitt metal layer in the repairing area; and carrying out dye penetrant inspection on the repaired area to ensure that the surface of the new babbitt metal layer has no defect. The method has the advantages of being good in repairing quality, free of shelling, small in workload and short in repairing period.

Description

Technical Field

[0001] The present invention belongs to the field of repairing the babbit alloy layer of the bearing bush for rotating machinery, and specifically relates to a method for repairing the babbit alloy layer of the bearing bush for rotating machinery. Background Art

[0002] Babbit alloy is a low-melting-point bearing alloy with hard particle phases distributed on a soft matrix. It has anti-friction characteristics and better adaptability and press-in performance compared with other bearing materials, so it is widely used in the support bearings of large rotating machinery.

[0003] The steam turbine bearing is one of the important components of the steam turbine. It needs to bear the entire weight of the rotor and the centrifugal force caused by the mass imbalance of the rotor, determine the correct radial position of the rotor in the cylinder, and ensure the clearance of the flow passage part. Each bearing bears a high load and axial force. The bearing bush is the part that contacts the journal of the sliding bearing, and its shape is a semi-cylindrical surface in the shape of a tile. During actual operation, the babbit alloy layer of the bearing bush is often scratched due to improper lubrication or worn out after long-term use, affecting the normal operation of the unit. Therefore, the bearing bush must be repaired or replaced. Existing repair methods include cold machining according to the original size or repair by fusion welding. Cold machining according to the original size is prone to problems such as cracks and deformation, and the repaired bearing bush may not be completely matched with the original bearing bush, resulting in a decrease in the fitting accuracy and affecting the normal operation of the unit; while the melting point of babbit alloy is low, and the heat control during the repair process is relatively high. When the fusion welding repair temperature is too high, there is a risk of the babbit alloy layer peeling off.

[0004] Therefore, there is an urgent need to provide a repair method that can solve the problems existing in the existing repair methods, such as poor repair quality, peeling off, large workload, long repair cycle, etc., and improve the service life of the unit as much as possible. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for repairing the babbit alloy layer of the bearing bush for rotating machinery with good repair quality, no peeling off, small workload, and short repair cycle in view of the deficiencies of the prior art.

[0006] The technical object of the present invention is achieved by the following technical solutions: A method for repairing the babbit alloy layer of the bearing bush for rotating machinery includes the following steps: S1, perform non-destructive testing on the bearing bush body, and accurately mark the area to be repaired; S2, mechanically grind the area to be repaired, completely remove the babbit alloy layer in the area to be repaired, and ensure that the base body is flat and clean; S3, perform non-destructive testing on the area near the area to be repaired again to confirm that there is no defect indication in the babbit alloy layer; S4, select the babbit alloy powder of the corresponding grade and dry it. The drying temperature is 60-90°C, and the drying time is 2-4h; S5. Use the dried babbitt alloy powder as raw material for cold spraying repair; S6. Program the spray gun path based on the geometry of the repair area, and complete the coating coverage after trial spraying; S7. Through ultrasonic re-inspection combined with interface quality, ensure that the repair area is well bonded to the substrate without defects exceeding the standard; S8. Finish machining the surplus on the surface of the new babbitt alloy layer in the repair area; S9. Conduct coloring flaw detection on the repair area to ensure that there are no defects on the surface of the new babbitt alloy layer.

[0007] Preferably, when the area to be repaired is multiple areas, repeat steps S1 - S9 for each area.

[0008] Preferably, it further includes S10. According to the specific requirements of the drawing, make the bearing shell meet the drawing dimensions and technical requirements through precision grinding.

[0009] Preferably, the cold spraying process parameters for cold spraying repair in S5 are: spraying temperature 80 - 200 °C; spraying distance 30 - 50 mm; spraying angle between 30 - 45°; spraying pressure 1.2 - 1.5 MPa.

[0010] Preferably, the non-destructive testing in S1 uses ultrasonic flaw detection or penetrant flaw detection for non-destructive testing.

[0011] Preferably, the mechanical grinding in S2 uses an angle grinder or a rotary file for grinding.

[0012] Preferably, in S2, organic solvents are used for cleaning, and ensure that the area to be repaired and within 100 mm of the edge are clean.

[0013] Preferably, the re - non - destructive testing in S3 uses ultrasonic flaw detection for non - destructive testing.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention does not need to remove all the original babbitt alloy layer, but only locally remove and then locally repair. Under the condition of ensuring the repair quality, it can effectively reduce the workload and repair cycle. The present invention has the advantages of good repair quality, no shelling, small workload, and short repair cycle.

[0015] 2. When the present invention adopts the cold spraying process for repair, the babbit alloy powder does not need to be melted, and only relies on plastic deformation deposition to form a coating. There is no phase change in the whole process, and the heat input is extremely small, avoiding the problems of thermal stress and thermal deformation that may be caused in the fusion welding repair process. The repair accuracy is high, and the subsequent machining amount is small. Specifically, through the cold spraying process, a mechanical interlock is formed between the babbit alloy powder and the substrate, and the bonding strength is significantly improved. Since the working temperature of cold spraying is much lower than the melting point of the material, the substrate will not be thermally shocked, avoiding the problems of thermal deformation and thermal stress, and is particularly suitable for repairing temperature-sensitive substrates. During the spraying process, the powder and the substrate will not oxidize and undergo phase change, maintaining the original properties of the material. Adopting this technical measure has the advantages of good repair quality, no shelling, small workload, and short repair cycle.

[0016] 3. The deposition efficiency of the present invention is high, and large-area surface repair can be quickly completed. By in-situ growing a babbit alloy coating with high density and mechanical properties matching those of the original metal substrate, the effect of repairing and enhancing the structural strength and service life is achieved. Specific embodiments

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, rather than all, of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and illustrated here can be arranged and designed in various different configurations.

[0018] Therefore, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0019] A method for repairing a babbit alloy layer of a bearing bush for a rotating machine, comprising the following steps: S1, perform non-destructive testing on the bearing bush body and accurately mark the area to be repaired.

[0020] In specific implementation, a comprehensive non-destructive inspection is performed on the bearing bush body to be repaired; the non-destructive inspection adopts Inspection methods such as ultrasonic flaw detection or penetrant flaw detection; at the same time, accurately mark the area to be repaired. Among them, the area to be repaired (area to be repaired) may be one or more areas to be repaired (areas to be repaired). Traditional methods require the overall stripping of the babbit layer, resulting in a high risk of matrix damage and resource waste. By accurately positioning the defect area through non-destructive testing, only the locally failed babbit layer needs to be removed, and the healthy part of the matrix is retained, reducing material loss by more than 50% and improving the repair efficiency by 30% - 40%. By adopting this technical measure, the workload and repair cycle can be effectively reduced while ensuring the repair quality.

[0021] S2, mechanically grind the area to be repaired to completely remove the babbit layer in the area to be repaired, ensuring that the matrix is flat and clean.

[0022] In specific implementation, mechanically grind the marked area to be repaired; generally, use a angle grinder or a rotary file for grinding; through grinding with an angle grinder or a rotary file to eliminate defects, completely remove the babbit layer in the marked area to be repaired, grind the contour of the area to be repaired to be smooth and round, and ensure that the bottom is flat and clean. Generally, clean with an organic solvent and ensure that the area to be repaired and within 100 mm of the edge are clean. By adopting this technical measure, the babbit layer in the area to be repaired can be completely removed, including areas with defects such as looseness, pinholes, and pores, thus avoiding new problems caused by these defects during subsequent repair processes and ensuring good bonding between the repair layer and the matrix. Grinding the area to be repaired to make its contour smooth and round and the bottom flat can better control the thickness and shape of the repair layer, thereby improving the repair accuracy and making the size and geometric shape of the repaired equipment closer to the original design requirements. It can quickly complete the preparation work for the area to be repaired, shorten the maintenance time, and improve the maintenance efficiency. Completely removing the babbit layer and making the surface flat and clean can provide a good foundation for subsequent repair work, enhance the bonding force between the repair layer and the matrix, and reduce the risk of repair layer peeling off. The contour of the repaired area to be repaired is smooth and round and the bottom is flat, which is convenient for the application and shaping of subsequent repair materials, improving the convenience of repair operations and the stability of repair quality.

[0023] S3, conduct non-destructive testing on the area near the area to be repaired again to confirm that there is no defect indication in the babbit layer.

[0024] In specific implementation, when conducting non-destructive testing on the area near the area to be repaired again, use ultrasonic flaw detection for non-destructive testing to confirm that there is no defect indication in the babbit layer. By adopting this technical measure, it can ensure that there are no defects in the bonding between the repair area and the matrix, and the qualified rate is increased to more than 99%, significantly reducing the rework rate, and it has the advantage of good repair quality.

[0025] S4, select the corresponding grade of babbit alloy powder and dry it, the drying temperature is 60 - 90 °C, and the drying time is 2 - 4 h.

[0026] In specific implementation, step S4 has the effects of improving the powder quality, optimizing the process effect and increasing the production efficiency. Adopting this technical measure has the advantages of good repair quality and short repair cycle.

[0027] Specifically, the drying treatment can effectively remove the moisture in the babbit alloy powder, preventing defects such as pores and looseness caused by water evaporation during the subsequent cladding or spraying process, thereby improving the quality and density of the repair layer. Appropriate drying temperature and time can evaporate the moisture on the surface of the powder particles, reduce the adhesion between particles, thereby improving the fluidity of the powder, which is beneficial to the uniform distribution and spreading of the powder during the spraying or cladding process.

[0028] Through the drying treatment, the moisture and impurities in the powder are removed, making the combination between the powder and the substrate closer, thereby enhancing the bonding strength between the repair layer and the substrate. The dried powder can spread and wet the substrate surface better during the cladding or spraying process, forming a more uniform and smooth repair layer, reducing surface defects and improving the surface quality after repair. The drying treatment can make the powder easier to operate and control in the subsequent processing, reducing the processing difficulties and time waste caused by the wet or sticky powder, thereby increasing the production efficiency. By improving the powder quality and process effect, the generation of repair layer defects and unqualified products is reduced, the scrap rate is lowered, and the production efficiency and economic benefits are increased.

[0029] S5. Use the dried babbit alloy powder as raw material for cold spray repair.

[0030] In specific implementation, during the cold spray process, the babbit alloy powder impacts the substrate surface under the action of high-speed air flow to form a coating. Since the spraying temperature is relatively low, the components in the powder are not prone to segregation, and can maintain the same chemical composition and microstructure as the raw material, thereby ensuring the uniformity of the coating.

[0031] Specifically, during the cold spray process, the babbit alloy powder does not undergo a melting phase change, and only achieves deposition through high-speed impact plastic deformation, realizing: zero thermal stress; the substrate temperature is always lower than 200°C, avoiding thermal deformation or residual stress accumulation, and a high-density coating; the coating porosity < 1%, and the bonding strength ≥ 80 MPa, which is superior to the traditional fusion welding process (porosity > 5%, bonding strength ≤ 50 MPa); precise repair; the controllable precision of the coating thickness reaches ±0.05 mm, and the subsequent machining allowance is reduced by 60%.

[0032] The cold spraying process parameters for cold spraying repair are as follows: spraying temperature is 80 - 200 °C; spraying distance is 30 - 50 mm; spraying angle is between 30 - 45°; spraying pressure is 1.2 - 1.5 MPa. Under the optimized process parameters, the powder particles can be fully deformed and form a good mechanical bond with the substrate, reducing the pores and defects in the coating and improving the densification of the coating.

[0033] Cold spraying repair also has the advantages of high repair efficiency and small heat influence. Specifically, through the cold spraying process, a mechanical interlock is formed between the babbit alloy powder and the substrate, and the bonding strength is significantly improved. The cold spraying technology can be used for rapid on-site repair without disassembling and transporting the equipment to a special repair workshop, reducing the repair cost and time. Since the working temperature of cold spraying is much lower than the melting point of the material, the substrate will not be thermally shocked, avoiding thermal deformation and thermal stress problems, and is particularly suitable for repairing temperature-sensitive substrates. During the spraying process, the powder and the substrate will not undergo oxidation and phase change, maintaining the original properties of the material. Adopting this technical measure has the advantages of good repair quality, no shelling, small workload, and short repair cycle.

[0034] The cold spraying coating has better wear resistance and fatigue resistance. The deposition efficiency of the cold spraying technology can reach more than 80%, and the spraying speed is fast, up to 3 kg / h, which can quickly complete the repair task and reduce the equipment downtime. Adopting the above technical measures, the deposition efficiency is high, and large-area surface repair can be quickly completed. By in-situ growing a babbit alloy coating with high densification and mechanical properties matching those of the original metal substrate, the effect of repairing and enhancing the structural strength and service life can be achieved.

[0035] S6, Program the spray gun path based on the geometry of the repair area and complete the coating coverage after trial spraying.

[0036] During specific implementation, by programming the repair path of the spray gun, it can ensure that the spray gun precisely covers the area to be repaired, avoiding overspray or omission of the coating, and improving the accuracy and consistency of the repair. The programmed path can be flexibly adjusted according to the complex shape of the area to be repaired, ensuring that the spray gun can adapt to the repair requirements of various special parts such as curved surfaces and grooves, and realizing uniform spraying on complex-shaped surfaces. The programmed path can optimize the movement trajectory of the spray gun, reduce unnecessary movement and repeated spraying, improve the spraying efficiency, and shorten the repair time.

[0037] Through the trial run of the spray gun, problems in path planning can be discovered and corrected in advance, avoiding errors during the formal spraying process and reducing repair failures or rework caused by human operation errors. Precise path programming helps control spraying parameters, making the coating thickness more uniform and reducing performance differences caused by uneven coating thickness. By optimizing the spraying path and parameters, the bonding strength between the coating and the substrate can be improved, ensuring that the repaired coating has good mechanical properties. Precise path programming and trial run of the spray gun can reduce unnecessary spraying, reduce material waste, and improve material utilization rate. Automated path programming reduces the complexity and time of manual operation, reducing labor costs. The combination of the programmed path and the trial run of the spray gun enables the cold spraying technology to quickly carry out repairs on-site without disassembling and transporting the equipment to a dedicated repair workshop, reducing repair costs and time.

[0038] Adopting the technical solution of completing the spray gun repair path programming according to the size of the area to be repaired and then conducting formal spraying after the trial run of the spray gun has the following technical advantages: precise repair, adaptability to complex shapes, improvement of repair efficiency, reduction of human errors, enhancement of repair quality, reduction of repair costs, and enhancement of applicability and flexibility.

[0039] S7. Through ultrasonic re-inspection combined with interface quality, ensure good bonding between the repaired area and the substrate without excessive defects.

[0040] During specific implementation, through multi-stage flaw detection, before and after repair, non-destructive testing such as ultrasonic testing is carried out to ensure no defects, thus avoiding the problem of rework and effectively ensuring the repair efficiency.

[0041] S8. Finish machining the surplus on the surface of the new Babbit alloy layer in the repaired area; During specific implementation, according to the specific shape and dimensional requirements of the repair area, select appropriate processing methods such as milling and grinding. For example, for bearing shell parts, a lathe can be used for finish machining.

[0042] During the machining process, appropriate cutting parameters such as cutting speed, feed rate, and cutting depth need to be set according to the material characteristics and machining requirements. For example, during milling, the rotation speed and feed speed of the milling cutter need to be controlled to avoid damaging the Babbit alloy layer.

[0043] According to the set processing parameters, finish machining the surplus on the surface of the new Babbit alloy layer in the repaired area to make it reach the designed size and surface roughness requirements. During the machining process, the machining quality needs to be continuously inspected and the processing parameters adjusted in a timely manner.

[0044] After finish machining, quality inspection of the machined surface needs to be carried out, including indicators such as dimensional accuracy, surface roughness, and hardness. If machining quality problems are found, rework or repair needs to be carried out in a timely manner.

[0045] Precautions

[0046] During the finishing process, attention should be paid to avoiding over - processing, so as not to affect the performance and service life of the babbitt alloy layer.

[0047] Due to the relatively low melting point of the babbitt alloy, it is necessary to control the processing temperature well during the processing to avoid softening or melting of the alloy layer caused by too high temperature.

[0048] The purpose of finishing is to restore the repaired part to the original size and accuracy requirements, so it is necessary to ensure the accuracy and quality of processing.

[0049] S9, conduct color penetration inspection on the repair area to ensure that the surface of the new babbitt alloy layer is defect - free.

[0050] In specific implementation, the color penetration inspection method is used for non - destructive testing of the repaired area after finishing. It has the advantages of high detection accuracy. At the same time, this method has a high detection sensitivity for surface - opening defects, and can effectively detect defects such as cracks and pores on the surface of the babbitt alloy layer, ensuring that the surface quality after repair meets the requirements.

[0051] By conducting color penetration inspection on the repair area, the repair quality can be strictly controlled to ensure that the surface of the new babbitt alloy layer is defect - free, thereby improving the performance and reliability of the repaired part. This helps to extend the service life of the part and reduce the failures and maintenance costs caused by surface defects.

[0052] By timely detecting and repairing the defects on the surface of the new babbitt alloy layer through color penetration inspection, it is possible to avoid greater - scale damage and more complex repair work caused by the expansion of defects. This helps to reduce the maintenance cost and improve the economy and practicality of the equipment.

[0053] During the repair process, color penetration inspection can quickly and accurately detect defects, shorten the repair cycle, and improve production efficiency. At the same time, the quality of the repaired part is guaranteed, reducing rework and delays caused by quality problems, and further improving production efficiency and economic benefits.

[0054] The equipment required for color penetration inspection is relatively simple, mainly including penetrant, cleaner, developer, etc., and does not require complex instruments and equipment. This makes this method more convenient and fast in actual operation and is easy to carry out under various on - site conditions.

[0055] The operation steps of color penetration inspection are relatively simple, mainly including pre - cleaning, penetration, cleaning, imaging, and observation, etc. These steps are easy to master and operate, reducing the operation difficulty and cost.

[0056] S10, according to the specific requirements of the drawing, make the bearing shell meet the drawing size and technical requirements through fine grinding.

[0057] In specific implementation, adopting this technical measure has the advantages of high-precision dimension control, optimized surface roughness, ensuring the bonding quality between the coating and the substrate, improving assembly reliability, etc.

[0058] Specifically, through the precision grinding process, key dimension parameters such as the inner diameter, roundness, and cylindricity of the bearing bush can be strictly guaranteed to meet the tolerance range of the design drawing (usually reaching IT6-IT7 level precision), ensuring uniform clearance in the fit with the journal, reducing friction loss, and improving operation stability.

[0059] Cold spraying repair may introduce the problem of uneven coating thickness. Precision grinding can uniformly remove the surplus to make the final dimensions consistent. After precision grinding, the surface roughness can reach Ra 0.4 - 0.8μm, significantly reducing the contact friction between the bearing bush and the journal, avoiding abnormal wear, and extending the service life.

[0060] A smooth surface is conducive to the formation and maintenance of the lubricating oil film, improving the bearing capacity and anti-seizure performance of the bearing.

[0061] During the precision grinding process, if there are problems with poor bonding in the coating (such as pores, delamination), the processing stress may cause local spalling, indirectly verifying the coating bonding strength. Through progressive precision grinding, the residual stress of the cold-sprayed coating can be released, avoiding deformation or cracking caused by stress release during service.

[0062] The standardized precision-ground bearing bush can directly replace the original factory parts without additional adjustment, reducing equipment downtime and maintenance costs.

[0063] Precision dimensions and surface quality enable the bearing bush to maintain a stable oil film under high-speed and heavy-load conditions, reducing vibration and noise.

[0064] Precision grinding only needs to remove a small amount of surplus (usually 0.05 - 0.2mm), avoiding material loss caused by excessive cutting in traditional machining. It is especially suitable for the high-cost repair scenario of precious metal babbit alloy. Combined with CNC grinding machine programming, efficient processing can be achieved through parametric paths during batch repair, improving the overall repair efficiency. Adopting this technical measure is not only the end point of dimension trimming but also a key guarantee link for repair quality. Through high-precision machining and surface optimization, it ensures that the performance of the repaired bearing bush reaches or exceeds the original factory standard, while taking into account economy and production efficiency.

[0065] The above has introduced in detail the technical solutions provided by the embodiments of the present invention. Specific examples are used herein to elaborate on the principles and implementation manners of the embodiments of the present invention. The description of the above embodiments is only applicable to helping understand the principles of the embodiments of the present invention; at the same time, for those of ordinary skill in the art, according to the embodiments 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 repairing the Babbitt alloy layer of a bearing bush for a rotating machine, characterized in that, It includes the following steps: S1, conduct non-destructive testing on the bearing shell body, and accurately mark the area to be repaired; S2, mechanically grind the area to be repaired, thoroughly remove the Babbitt alloy layer in the area to be repaired, and ensure that the base body is flat and clean; S3, conduct non-destructive testing on the area near the area to be repaired again to confirm that there is no defect indication in the Babbitt alloy layer; S4, select Babbitt alloy powder of the corresponding grade and dry it. The drying temperature is 60~90°C, and the drying time is 2~4h; S5, use the dried Babbitt alloy powder as raw material for cold spraying repair; S6, program the spray gun path based on the geometry of the repair area, and complete the coating coverage after trial spraying; S7, ensure good bonding between the repair area and the base body and no excessive defects through ultrasonic re-inspection combined with interface quality; S8, conduct finish machining on the surplus on the surface of the new Babbitt alloy layer in the repair area; S9, conduct dye penetrant inspection on the repair area to ensure that there are no defects on the surface of the new Babbitt alloy layer.

2. The repair method of the babbit alloy layer of the bearing bush for rotating machinery according to claim 1, characterized in that When the area to be repaired is multiple areas, repeat steps S1~S9 for each area.

3. The repair method of the babbitt alloy layer of the bearing bush for rotating machinery according to claim 1 or 2, characterized in that, It also includes S10, according to the specific requirements of the drawing, make the bearing shell meet the drawing dimensions and technical requirements through precision grinding.

4. The repair method of the babbitt alloy layer of the bearing bush for rotating machinery according to claim 1, characterized in that, The cold spraying process parameters for the cold spraying repair in S5 are: spraying temperature 80~200°C; spraying distance 30~50mm; spraying angle between 30~45°; spraying pressure 1.2~1.5MPa.

5. The repair method of the babbit alloy layer of the bearing bush for rotating machinery according to claim 1, characterized in that, The non-destructive testing in S1 uses ultrasonic flaw detection or penetrant flaw detection for non-destructive testing.

6. The repair method of the babbitt alloy layer of the bearing bush for rotary machinery according to claim 1, characterized in that, The mechanical grinding in S2 uses a angle grinder or a rotary file for grinding.

7. The repair method of the babbitt alloy layer of the bearing bush for rotating machinery according to claim 1, characterized in that, In S2, organic solvents are used for cleaning, and ensure that the area to be repaired and the area within 100mm of the edge are clean.

8. The repair method of the babbitt alloy layer of the bearing bush for rotating machinery according to claim 1, characterized in that, The re-conducted non-destructive testing in S3 uses ultrasonic flaw detection for non-destructive testing.