A pump rotor sleeve surface strengthening processing method

Abstract

The application discloses a kind of pump rotor sleeve surface strengthening processing method, steps include: selecting shaft sleeve base material, the shaft sleeve is annealed, the shaft sleeve is semi-finished after annealing, the shaft sleeve is vacuum quenching after semi-finished, the shaft sleeve is installed tooling after vacuum quenching, installs upper pressing plate and lower pressing plate and covers the shaft sleeve two end face respectively, the shaft sleeve is ion nitriding after installation tooling, the shaft sleeve is finished and ground after ion nitriding.The application eliminates internal stress by annealing treatment, improves the organization to improve machinability, semi-finishing provides size reference and margin guarantee, vacuum quenching enhances shaft sleeve hardness, strength and wear resistance, ion nitriding forms high-quality nitriding layer after installation tooling, improves surface performance, finishing and grinding guarantee size accuracy and smoothness, multiple processes significantly improve the wear resistance of shaft sleeve, prolong the life of rotor, greatly avoid wear and tear problem.

Description

Technical Field

[0001] This invention relates to the field of pump parts manufacturing technology, and specifically to a method for surface strengthening of a pump rotor bushing. Background Technology

[0002] In modern industrial pump systems, components such as packing, packing seals, and sealing rings are the main sealing methods to reduce leakage between the rotor and stator. As pump performance requirements continue to increase, the clearance between the rotor and stator is designed to be smaller and smaller. While this compact structure is beneficial to improving pump efficiency, it also brings significant technical challenges: an excessively small clearance can easily cause continuous scraping between the packing and other components on the stator side and rotor parts (especially the shaft sleeve area), resulting in long-term friction and wear on the rotor parts.

[0003] Furthermore, in actual operating conditions, the media transported by pumps often contain hard impurities such as crystalline particles. These particles, when flowing through narrow gaps, exacerbate abrasive wear, with a wear rate far exceeding that of simple frictional wear. Traditional solutions mainly involve selecting high-wear-resistant substrate materials or employing surface coating processes. However, these methods have significant limitations. Replacing the entire material with high-strength materials is too costly, while coating technologies such as thermal spraying are prone to problems such as insufficient adhesion and uneven thickness. Under complex alternating stress, they may also experience peeling failure. This invention proposes a new solution to address these issues. Summary of the Invention

[0004] To overcome at least one of the aforementioned drawbacks, this invention provides a method for surface strengthening of a pump rotor bushing. The objective of this invention can be achieved by employing the following technical solution: This application provides a method for surface strengthening of a pump rotor bushing, comprising the following steps: Select the bushing base material; Annealing treatment is performed on the bushing; The annealed bushing undergoes semi-finishing treatment; Vacuum quenching treatment is performed on the semi-finished bushing; After vacuum quenching, the bushing is fitted with an installation fixture, and the upper and lower pressure plates are installed to cover both ends of the bushing. The bushings are subjected to ion nitriding treatment after installation. The ion-nitrided bushing is then precision machined and ground.

[0005] In one possible implementation, the bushing matrix material includes 40NiCrMo, 40CrNiMoA, or ASTM A322.

[0006] In one possible implementation, the annealing process includes: Heating to 800℃~840℃ at a heating rate not exceeding 100℃ / h, and holding for at least 3 hours; After cooling to 300℃~400℃ at a rate not exceeding 50℃ / h, remove from the furnace and air cool.

[0007] In one possible implementation, the semi-finishing step includes: The outer diameter of the bushing is machined according to the design requirements; The inner diameter of the bushing is reserved with a margin of 0.5mm to 1.5mm; The end face of one end of the bushing retains a collet, the length of which is 20mm~30mm.

[0008] In one possible implementation, the vacuum quenching process includes: The shaft is fitted into a vacuum device and heated to 750℃~800℃ at a heating rate of 1℃ / min~3℃ / min, and held at that temperature for 10min~30min. Continue heating at a rate of 1℃ / min to 3℃ / min to 880℃ to 940℃, and hold for 10min to 30min; Introduce nitrogen gas at 1.5 Bar to 3.5 Bar to cool to 350℃ to 420℃, and hold at that temperature for 1 to 4 hours; After cooling to 50℃~60℃ by introducing nitrogen gas at a pressure of not less than 1.5 Bar, the furnace is removed and air-cooled.

[0009] In one possible implementation, the steps of the installation tooling process include: The lower pressure plate is placed in the ion nitriding furnace, and the vacuum-quenched bushing is placed on the lower pressure plate so that one end face of the bushing is completely in contact with the surface of the lower pressure plate, and the other end face is covered by the upper pressure plate. The upper pressure plate and the lower pressure plate cooperate to form a mechanical shielding of the inner hole and the end faces of the bushing, which is used to prevent the nitriding medium from penetrating into the inner hole and end face area of ​​the bushing.

[0010] In one possible implementation, the cross-sectional dimensions of the upper pressure plate and the lower pressure plate are larger than the cross-sectional dimensions of the bushing, and the thickness of the upper pressure plate and the lower pressure plate is 10±2mm.

[0011] In one possible implementation, the ion nitriding treatment is carried out in a glow discharge ion nitriding furnace at 520°C to 560°C for 20 to 26 hours. After furnace cooling to 150°C to 200°C, the furnace is removed and air-cooled.

[0012] In one possible implementation, the finishing and grinding steps include: By clamping the outer circle of the chuck, and using the outer circle and end face as a reference, the dial indicator is used for alignment, and the alignment deviation shall not exceed 0.02mm; After precision machining the inner hole according to the design dimensions, leave a 0.4mm allowance along the entire length and remove the chuck by wire cutting. Clean and grind the burrs and flash on the cut part. The end face is ground and the burrs on the end face are removed simultaneously.

[0013] In one possible implementation, applicable to pump rotor parts, the nitrided layer of the shaft sleeve obtained by the surface strengthening processing method of the pump rotor shaft sleeve has a brittleness level not exceeding level II, a hardness of HV5 > 502, a substrate hardness of HBW ≥ 311, and a nitrided layer depth ≥ 0.3 mm.

[0014] The beneficial technical effects of this invention are as follows: According to this disclosure, the surface strengthening processing method for the pump rotor bushing effectively eliminates the internal stress of the material through annealing, improves the microstructure, and enhances the machinability of the material. The semi-finishing process provides accurate dimensional references and machining allowances for subsequent processing. Vacuum quenching improves the hardness and strength of the bushing and enhances its wear resistance. After installation with tooling, ion nitriding is performed to form a high-quality nitrided layer on the surface of the bushing, which significantly improves the surface hardness, anti-galling, and corrosion resistance. The final finishing and grinding ensure the dimensional accuracy and surface finish of the bushing. Through multiple processes, the wear resistance of the bushing surface is significantly improved, the service life of the rotor is extended, and wear problems caused by insufficient clearance or medium particles are avoided. Attached Figure Description

[0015] The following are given by way of example and without limitation in the accompanying drawings: Figure 1 This diagram shows the structure of the bushing, upper pressure plate, and lower pressure plate after the tooling has been installed according to an embodiment of the present invention. Figure 2 A schematic diagram of the bushing structure of the present invention is shown; Figure 3 A schematic flowchart of the processing method according to an embodiment of the present invention is shown.

[0016] In the diagram: 1. Bushing; 2. Upper pressure plate; 3. Lower pressure plate. Detailed Implementation

[0017] In the following detailed disclosure, these embodiments are fully described with reference to the accompanying drawings. In order to enable those skilled in the art to understand and clarify the technical solution of the present invention more clearly, the embodiments described below are not limited thereto. The present invention will be further described in detail below with reference to the embodiments and the accompanying drawings.

[0018] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0019] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0020] This application provides a method for surface strengthening of a pump rotor bushing, such as... Figure 3 As shown, the steps include: selecting the base material of bushing 1, annealing bushing 1, semi-finishing bushing 1 after annealing, vacuum quenching bushing 1 after semi-finishing, installing mounting fixtures on bushing 1 after vacuum quenching, installing upper pressure plate 2 and lower pressure plate 3 to cover both ends of bushing 1 respectively, ion nitriding bushing 1 after installation fixtures, and finishing and grinding bushing 1 after ion nitriding.

[0021] The pump rotor bushing surface strengthening processing method provided in this embodiment effectively eliminates internal stress in the material, improves the microstructure, and enhances the machinability of the material through annealing. Semi-finishing provides accurate dimensional references and machining allowances for subsequent processing. Vacuum quenching improves the hardness and strength of the bushing 1 and enhances its wear resistance. After installation with tooling, ion nitriding is performed to form a high-quality nitriding layer on the surface of the bushing 1, which significantly improves surface hardness, anti-galling, and corrosion resistance. The final finishing and grinding ensure the dimensional accuracy and surface finish of the bushing 1. Through multiple processes, the wear resistance of the bushing 1 surface is significantly improved, the service life of the rotor is extended, and wear problems caused by insufficient clearance or medium particles are avoided.

[0022] In one possible implementation, the bushing matrix material includes 40NiCrMo, 40CrNiMoA, or ASTM A322 4340 type materials.

[0023] It is understandable that the pump rotor bushing is made of 40NiCrMo, 40CrNiMoA or materials conforming to ASTM A322 4340. These materials have excellent mechanical properties, good strength and toughness, which can ensure that the bushing is not easily deformed under complex stress environment, can effectively resist impact loads and prevent brittle fracture.

[0024] The bushing base is made of 40NiCrMo material. Nickel and molybdenum alloying elements enhance toughness and fatigue resistance. Alloy structural steel has the characteristics of high strength and high toughness, excellent hardenability, and is suitable for impact load environments, such as bushings in mining equipment.

[0025] The bushing base is made of 40CrNiMoA material. The alloy structural steel has the characteristics of high strength and high toughness, good hardenability and resistance to overheating, and excellent tensile strength, making it suitable for precision components such as aero-engine shafts.

[0026] The bushing base is made of ASTM A322 4340 type material, which is American standard alloy steel with high strength and high toughness, good high temperature stability, and can withstand working conditions above 400℃, making it suitable for turbine bushings.

[0027] In one possible implementation, the annealing process includes: heating to 800°C~840°C at a heating rate not exceeding 100°C / h, holding at that temperature for at least 3 hours, and then cooling to 300°C~400°C at a cooling rate not exceeding 50°C / h before air cooling.

[0028] In the annealing process, the slow and stable heating at a rate not exceeding 100℃ / h allows the bushing material to fully and uniformly absorb heat, avoiding internal stress caused by sudden temperature changes. The holding time of not less than 3 hours allows the internal structure of the material to fully transform and achieve a uniform state. Then, the material is cooled to a specific temperature range at a slow rate not exceeding 50℃ / h before being removed from the furnace and air-cooled. This further eliminates residual stress inside the material, effectively improves the processing performance of the material, and lays a good foundation for subsequent processing steps.

[0029] In one possible implementation, the semi-finishing step includes: machining the outer diameter of the bushing 1 according to the design requirements, leaving a diameter allowance of 0.5mm to 1.5mm in the inner hole of the bushing 1, and retaining a chuck on the end face of one end of the bushing 1, with a length of 20mm to 30mm.

[0030] In the semi-finishing step, the bushing after annealing is semi-finished. The outer circle of bushing 1 is machined according to the design requirements and tolerances. An appropriate allowance of 0.5mm to 1.5mm is reserved for the inner hole, preferably about 1mm, to leave adjustment space for subsequent finishing. This helps to ensure the final dimensional accuracy and surface quality of the inner hole. A chuck with a length of 20mm to 30mm is reserved to facilitate clamping bushing 1 during the machining process. This can effectively prevent bushing 1 from loosening during machining and ensure the stability and safety of the machining process.

[0031] In one possible implementation, the vacuum quenching process includes: placing the bushing 1 into a vacuum device, heating it to 750°C to 800°C at a heating rate of 1°C / min to 3°C / min, and holding it at that temperature for 10 min to 30 min; continuing to heat it to 880°C to 940°C at a heating rate of 1°C / min to 3°C / min, and holding it at that temperature for 10 min to 30 min; cooling it to 350°C to 420°C by introducing nitrogen gas at a rate of 1.5 Bar to 3.5 Bar, holding it at that temperature for 1 h to 4 h, and then cooling it to 50°C to 60°C by introducing nitrogen gas at a rate of not less than 1.5 Bar before removing it from the furnace and air cooling it.

[0032] In the vacuum quenching process, a staged, slow heating and holding process at a heating rate of 1℃ / min to 3℃ / min ensures that the bushing 1 material is heated fully and uniformly, resulting in a stable transformation of the material's internal structure and preparing it for subsequent quenching. Nitrogen gas cooling and staged holding not only effectively prevent cracking caused by excessively rapid cooling but also allow for precise control of the material's microstructure and properties, improving the hardness and wear resistance of the bushing 1 while enhancing its dimensional stability.

[0033] In one possible implementation, such as Figure 1 and Figure 2 As shown, the installation tooling process includes: placing the lower pressure plate 3 in the ion nitriding furnace, placing the vacuum-quenched bushing 1 on the lower pressure plate 3, so that one end face of the bushing 1 is completely in contact with the surface of the lower pressure plate 3, and the other end face covers the upper pressure plate 2. The upper pressure plate 2 and the lower pressure plate 3 cooperate to form a mechanical shielding of the inner hole and the end faces of the bushing 1, which is used to prevent the nitriding medium from penetrating into the inner hole and end face area of ​​the bushing 1.

[0034] In the tooling installation process, the lower pressure plate 3 is placed in the ion nitriding furnace, the bushing 1 is placed properly, and the upper pressure plate 2 is used to form a mechanical shield, which can effectively prevent the nitriding medium from penetrating into the key parts of the bushing 1. While ensuring the stable performance of the bushing 1 in a specific area, it ensures that the nitriding treatment is only carried out in the predetermined area, thereby precisely controlling the nitriding effect of the bushing 1 and improving product quality and performance.

[0035] In one possible implementation, such as Figure 1As shown, the cross-sectional dimensions of the upper pressure plate 2 and the lower pressure plate 3 are larger than the cross-sectional dimensions of the bushing 1, and the thickness of the upper pressure plate 2 and the lower pressure plate 3 is 10±2mm.

[0036] The upper pressure plate 2 and the lower pressure plate 3 can be the same size or different. Figure 1 The diagram shows that the upper pressure plate 2 and the lower pressure plate 3 are identical and are circular plates. The upper pressure plate 2 and the lower pressure plate 3 can be circular plates, square plates or other shapes, as long as the end face can cover the end face of the bushing 1. The upper pressure plate 2 and the lower pressure plate 3 are not subjected to force and do not bear pressure. The diversity of shapes can adapt to different scenario requirements.

[0037] The thickness of the upper pressure plate 2 and the lower pressure plate 3 is set at about 10mm and has a certain range of elasticity, which ensures the strength and stability of the pressure plate itself, while also taking into account the flexibility of actual operation.

[0038] In one possible implementation, the ion nitriding treatment is carried out in a glow discharge ion nitriding furnace at 520°C to 560°C for 20 to 26 hours. After the furnace is cooled to 150°C to 200°C, the ion nitriding treatment is removed from the furnace and air-cooled.

[0039] In the ion nitriding process, the relatively precise temperature range of 520℃ to 560℃ and the relatively long duration of 20h to 26h allow nitrogen atoms to fully penetrate the surface of bushing 1, forming an excellent nitrided layer. This significantly improves the surface hardness, wear resistance, corrosion resistance, and fatigue resistance of bushing 1. The subsequent reasonable furnace cooling process effectively reduces internal stress, prevents bushing cracking, ensures stable performance, and extends the service life of bushing.

[0040] In one possible implementation, the finishing and grinding steps include: using the outer diameter of the clamped chuck as a reference, and using the outer diameter and end face as a reference for dial indicator alignment, with an alignment deviation not exceeding 0.02mm; after precision machining the inner hole according to the design dimensions, leaving a 0.4mm allowance along the entire length and removing the chuck by wire cutting, and cleaning and grinding the burrs and flash on the cut area; grinding the end face and simultaneously cleaning the burrs and flash on the end face.

[0041] In the finishing and grinding steps, the outer diameter and end face of the chuck are used as references for dial indicator alignment and deviation is strictly controlled, providing a precise positioning basis for subsequent processing and ensuring machining accuracy. The inner hole is precision turned with reasonable allowance, and the chuck is precisely removed using wire cutting. The cut area is then cleaned and ground to ensure the quality of the inner hole and its surroundings. The end face grinding and burr removal are carried out simultaneously, making the end face flat and smooth, effectively improving the machining quality and accuracy of the parts.

[0042] In one possible implementation, the surface strengthening processing method for pump rotor bushing 1 provided in this embodiment is applicable to pump rotor parts. The brittleness level of the nitrided layer of bushing 1 obtained by the surface strengthening processing method for pump rotor bushing 1 does not exceed level II, the hardness of the nitrided layer reaches HV5>502, the hardness of the substrate HBW≥31, and the depth of the nitrided layer ≥0.3mm.

[0043] After being treated by the surface strengthening processing method for the pump rotor bushing provided in this embodiment, the nitrided layer of the bushing exhibits excellent performance, with the brittleness level controlled to an extremely low level II, greatly enhancing the reliability of the bushing; the nitrided layer has extremely high hardness, HV5>502, significantly improving the surface wear resistance; the substrate hardness HBW≥311 ensures the overall strength; and the nitrided layer depth ≥0.3mm provides a solid guarantee for the long-term stable operation of the bushing.

[0044] This embodiment provides specific steps for a method of strengthening the surface of a pump rotor bushing: S1. Bushing material: 40NiCrMo7 is selected as the bushing material; S2. Annealing treatment: The bushing is heated to 820℃ at a heating rate of 60℃ / h, held at this temperature for 3h, and then cooled to 350℃ at a rate of 40℃ / h, and then removed from the furnace and air-cooled. S3. Semi-finishing: A semi-finishing operation is performed on the annealed bushing. The outer diameter of the bushing is machined according to the design requirements and tolerances, with a 1mm diameter allowance left for the inner hole. A chuck with a length of 25mm is provided on one end face. See attached dimensions for specific dimensions. Figure 2 ; S4. Vacuum quenching treatment: The semi-finished shaft is placed in a vacuum equipment and heated to 780°C at a heating rate of 2°C / min, and held for 30 min; then the temperature is further increased to 920°C at a heating rate of 2°C / min, and held for 20 min; then 1.5 Bar nitrogen gas is introduced for cooling, and when the temperature is cooled to 350°C, it is held for 2 h, and then cooled to 50°C with 1.5 Bar nitrogen gas. Finally, it is removed from the furnace and air-cooled. S5. Installation Fixture Treatment: Select a 10mm thick, 250mm diameter outer plate as the upper and lower pressure plates. Place the lower pressure plate into the ion nitriding furnace, and place the vacuum-quenched bushing on the lower pressure plate, ensuring that one side of the bushing's end face rests entirely on the lower pressure plate. Cover the other side of the bushing's end face with the upper pressure plate, ensuring that the other side of the bushing's end face is completely covered by the upper pressure plate. Simultaneously, mechanical protection measures are used for the bushing's inner bore and end face to prevent nitriding. S6. Ion Nitriding Treatment: Ion nitriding treatment is carried out in a glow discharge ion nitriding furnace at 540℃ for 24 hours, followed by furnace cooling to 200℃, and then air cooling after removal from the furnace. S7. Finishing and Grinding: Clamp the outer diameter of the chuck, and use a dial indicator to align it according to the outer diameter and end face. The allowable deviation is 0.02mm. Finish machine the inner hole according to the drawing dimensions, and then leave a 0.4mm allowance along the entire length. Remove the chuck by wire cutting, and clean and grind the burrs generated at the cutting area. Grind the end face and clean the burrs generated at the end face.

[0045] The performance of the pump rotor bushing obtained by the surface strengthening processing method of this embodiment is shown in Table 1.

[0046] Table 1 In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0048] In view of the detailed description above, these and other changes can be made to these embodiments, and this written description includes embodiments of the best mode that disclose the invention. The patent scope of the invention is defined by the claims, which are not limited by this disclosure. The scope of protection of the invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the invention disclosed herein, based on the technical solutions and concepts of the invention, are within the scope of protection of the invention.

Claims

1. A method for surface strengthening of a pump rotor bushing, characterized in that the steps include... include: Select the bushing base material; Annealing treatment is performed on the bushing; The annealed bushing undergoes semi-finishing treatment; Vacuum quenching treatment is performed on the semi-finished bushing; After vacuum quenching, the bushing is fitted with an installation fixture, and the upper and lower pressure plates are installed to cover both ends of the bushing. The bushings are subjected to ion nitriding treatment after installation. The ion-nitrided bushing is then precision machined and ground.

2. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The bushing base material includes 40NiCrMo7, 40CrNiMoA, or ASTM A322.

3. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The annealing process includes the following steps: Heating to 800℃~840℃ at a heating rate not exceeding 100℃ / h, and holding for at least 3 hours; After cooling to 300℃~400℃ at a rate not exceeding 50℃ / h, remove from the furnace and air cool.

4. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The semi-finishing steps include: The outer diameter of the bushing is machined according to the design requirements; The inner diameter of the bushing is reserved with a margin of 0.5mm to 1.5mm; The end face of one end of the bushing retains a collet, the length of which is 20mm~30mm.

5. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The vacuum quenching process includes the following steps: The shaft is fitted into a vacuum device and heated to 750℃~800℃ at a heating rate of 1℃ / min~3℃ / min, and held at that temperature for 10min~30min. Continue heating at a rate of 1℃ / min to 3℃ / min to 880℃ to 940℃, and hold for 10min to 30min; Introduce nitrogen gas at 1.5 Bar to 3.5 Bar to cool to 350℃ to 420℃, and hold at that temperature for 1 to 4 hours; After cooling to 50℃~60℃ by introducing nitrogen gas at a pressure of not less than 1.5 Bar, the furnace is removed and air-cooled.

6. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The steps for processing the installation tooling include: The lower pressure plate is placed in the ion nitriding furnace, and the vacuum-quenched bushing is placed on the lower pressure plate so that one end face of the bushing is completely in contact with the surface of the lower pressure plate, and the other end face is covered by the upper pressure plate. The upper pressure plate and the lower pressure plate cooperate to form a mechanical shielding of the inner hole and the end faces of the bushing, which is used to prevent the nitriding medium from penetrating into the inner hole and end face area of ​​the bushing.

7. The method for surface strengthening of the pump rotor bushing according to claim 6, characterized in that, The cross-sectional dimensions of the upper pressure plate and the lower pressure plate are larger than the cross-sectional dimensions of the bushing, and the thickness of the upper pressure plate and the lower pressure plate is 10±2mm.

8. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The ion nitriding treatment is carried out in a glow discharge ion nitriding furnace at 520℃~560℃ for 20h~26h. After furnace cooling to 150℃~200℃, the furnace is removed and air-cooled.

9. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, The finishing and grinding steps include: By clamping the outer circle of the chuck, and using the outer circle and end face as a reference, the dial indicator is used for alignment, and the alignment deviation shall not exceed 0.02mm; After precision machining the inner hole according to the design dimensions, leave a 0.4mm allowance along the entire length and remove the chuck by wire cutting. Clean and grind the burrs and flash of the cut part. The end face is ground and the burrs on the end face are removed simultaneously.

10. The method for surface strengthening of the pump rotor bushing according to claim 1, characterized in that, Applicable to pump rotor parts, the nitrided layer of the shaft sleeve obtained by the surface strengthening processing method of the pump rotor shaft sleeve has a brittleness level not exceeding level II, a hardness of HV5 > 502, a base material hardness of HBW ≥ 311, and a nitrided layer depth ≥ 0.3 mm.

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