Device for manufacturing Cr-reducing coating on surface of steam turbine rotor and using method of device

Abstract

The invention discloses a device for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor and a using method of the device, the device comprises a rack, the rack is provided with a circular-arc-shaped rotor shaft machining channel, and symmetrical and movable radial telescopic rods are arranged on the two sides of the rotor shaft machining channel respectively; spraying devices are arranged at the machining ends of the radial telescopic rods. A plurality of semicircular machining grooves are formed in the rotor shaft machining channel at intervals, friction wheels making contact with an external rotor shaft are arranged on the top surfaces of the semicircular machining grooves, and the semicircular machining grooves and the rack at the bottom define a powder recycling bin. The laser ranging device on the powder spraying gun is used for achieving solid deposition through cooperation of the laser device and the powder sprayer, automatic spraying of a machine is achieved, heat input is small, heat damage to the surface of a rotor shaft is avoided, the element diffusion phenomenon is avoided, and the Cr reducing efficiency is high. The powder spraying guns and the laser devices on the two transverse sides of the rotor shaft are adopted for simultaneous machining, complete covering can be guaranteed, coating quality is improved, and production efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of material surface treatment and remanufacturing, and in particular to an apparatus and method for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor. Background Technology

[0002] my country is rich in coal resources, and coal-fired power plants provide the majority of the country's electricity. With the continuous increase in electricity demand, coal-fired power generation technology is developing towards high-parameter ultra-supercritical thermal power units with higher efficiency, lower coal consumption, and lower pollutant emissions. The turbine rotor is the core component of the turbine generator unit, operating under high temperature, high pressure, high stress, and complex media environments. High-Cr heat-resistant steel, possessing excellent toughness, oxidation resistance, corrosion resistance, high creep strength, and low expansion performance, is widely used in the manufacture of ultra-supercritical turbine rotors. However, with the increase of the Cr mass fraction in the material, the frictional characteristics between the rotor journal and the bearing deteriorate, and abnormal wear problems such as sticking and seizing are prone to occur in key parts such as the journal and sealing groove. Traditionally, techniques such as welding and laser cladding are used to prepare low-Cr alloy coatings on the journal surface to improve the wear resistance of the rotor shaft surface. However, these technologies have significant drawbacks: First, they are high-temperature processes, and the large heat input causes the base material, especially chromium, to diffuse into the coating, leading to element dilution. This necessitates multiple coating layers to reduce the surface chromium content to the required range, resulting in low processing efficiency. Second, high temperatures easily cause workpiece deformation, high residual stress, and deterioration of microstructure and properties.

[0003] Cold spraying, a solid-state deposition technology, relies on compressed gas to propel powder particles at high speeds against a substrate, depositing a coating through the intense plastic deformation of the particles. Compared to heat-input technologies, cold spraying operates at temperatures far below the material's melting point, effectively suppressing oxidation, phase transformation, and element diffusion. It also offers advantages such as high additive manufacturing efficiency and the ability to manufacture large components. Theoretically, it is an ideal solution to the challenge of manufacturing low-chromium coatings for rotor shaft surfaces. However, conventional cold spraying techniques require extremely high substrate plasticity, making it difficult to achieve high-bonding-strength and dense coatings on the high-strength steel commonly used in turbine rotor shafts, thus limiting its application in this field.

[0004] Therefore, there is an urgent need to develop a new composite process and device that can both utilize the low-temperature advantage of solid-state deposition technology to suppress chromium diffusion and overcome its insufficient bonding strength. Summary of the Invention

[0005] This invention addresses the problems of low Cr reduction efficiency, inability to achieve full coverage, and cumbersome processes in traditional Cr reduction treatment technologies for turbine rotor surfaces. It proposes a device and method for manufacturing Cr reduction coatings on turbine rotor surfaces. The core concept of this invention lies in applying laser-assisted solid-state deposition technology to deposit a low-Cr coating on the rotor journal surface. By combining the characteristics of solid-state deposition technology with the large-area manufacturing of protective coatings, it avoids the poor Cr reduction efficiency caused by Cr diffusion into the coating due to excessive heat input from the high-Cr substrate. Simultaneously, it enhances the bonding between particles in the coating and between the coating and the substrate, reduces porosity, improves the wear resistance and tensile properties of the coating, and extends the service life of the rotor journal.

[0006] In a first aspect, the present invention proposes an apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor, comprising a frame 1, an arc-shaped rotor shaft processing channel provided longitudinally on the frame 1, longitudinal Z-axis moving devices 6 provided on both transverse sides of the rotor shaft processing channel, Y-axis moving devices 7 provided on the Z-axis moving devices 6, the Y-axis moving devices 7 being slidable longitudinally along the Z-axis moving devices 6; transverse radial telescopic rods 3 provided on the Y-axis moving devices 7, the radial telescopic rods 3 being slidable up and down along the Y-axis moving devices 7; the ends of the two radial telescopic rods 3 facing each other are defined as processing ends, and each processing end of the radial telescopic rods 3 is provided with a spraying device; The rotor shaft processing channel is provided with several semi-circular processing grooves 14 with spacing along the longitudinal direction. The top surface of the semi-circular processing groove 14 is provided with a friction wheel 4 that contacts the external rotor shaft 13. The space enclosed by the adjacent semi-circular processing grooves 14 and the bottom frame 1 is defined as the powder recovery chamber 11. The spraying device includes a swing mechanism 10 located inside the processing end of the radial telescopic rod 3, with a powder spray gun 2 and a laser 9 connected to the longitudinal sides of the swing mechanism 10, respectively.

[0007] More specifically, the oscillating mechanism 10 includes a longitudinal rotating shaft 101, on which a driven gear 102 is fitted, meshing with an external drive mechanism 103; the two ends of the rotating shaft 101 are connected to the laser 9 and the powder spraying gun 2, respectively. By driving the worm gear 103 with a motor to drive the turbine 102, the powder spraying gun can oscillate adaptively, ensuring that the axis of the powder spraying gun is always aligned with the normal direction of the surface to be sprayed on the rotor shaft during the spraying process.

[0008] More specifically, the laser 9 and the powder spraying gun 2 are connected to the swing mechanism 10 via a metal sleeve; the powder spraying gun 2 is perpendicular to the surface to be coated on the outer rotor shaft, and the powder spraying gun and the laser point to the same point on the rotor shaft surface within the rotor shaft processing channel. This ensures that the laser spot and the powder spraying spot coincide during operation.

[0009] More specifically, the top of the frame 1 is equipped with a flexible wear-resistant cover 8, which together with the frame 1 forms a working space to accommodate the rotor shaft processing channel; the bottom of the powder recovery chamber 11 is provided with a negative pressure suction port 12, which is connected to a negative pressure suction machine 5.

[0010] More specifically, the powder spray gun 2 is equipped with a laser rangefinder to monitor and adjust the spraying distance in real time during the spraying process; the nozzle of the powder spray gun 2 is a Laval nozzle, and the outlet shape of the Laval nozzle is circular.

[0011] Preferably, the angle between the powder spraying gun and the laser is 45°. When the powder spraying gun nozzle maintains a processing distance of 30mm from the surface of the rotor shaft to be coated, the laser spot and the powder spraying spot can be completely overlapped. Secondly, the present invention provides a method for using the above-mentioned apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor, the steps of which include: S1. The equipment used for manufacturing the Cr-reducing coating on the surface of the steam turbine rotor is started and its status is checked by the staff; S2. Pre-treat the surface of the rotor to be machined and place it in the rotor shaft machining channel; S3. Connect the powder feeder to the powder spraying gun, load low-Cr alloy powder into the powder feeder, and set relevant parameters, including carrier gas, carrier gas pressure, carrier gas preheating temperature, powder feeding rate, spraying gun moving speed and laser power. S4. Based on the outer diameter of the rotor shaft journal, adjust the powder spraying guns on both sides of the rotor shaft to be perpendicular to the rotor shaft surface. Monitor the spraying distance in real time through the laser rangefinder on the powder spraying gun, and maintain the preset spraying distance through feedback control. S5. Start the friction wheel 4 on the semi-circular working groove. The friction wheel 4 drives the rotor shaft 13 to rotate. S6. The equipment starts working. Laser 9 emits laser to preheat the surface of the rotor shaft. Powder spraying gun 2 sprays low-Cr alloy powder. Laser 9 and powder spraying gun 2 on both sides of the rotor shaft 13 are synchronously driven by the Z-axis moving device 6. They start to move longitudinally from the spraying start point and form a spiral deposition trajectory on the surface of the rotating rotor shaft 13 to prepare the coating until the spraying work of the entire rotor shaft 13 is completed. At the same time, negative pressure suction port 12 recovers the low-Cr alloy powder that falls into the powder recovery chamber 11. S7. After the spraying is completed, the coating is measured; the powder recovered by the negative pressure suction port 12 is processed and sent to the powder feeder for later use.

[0012] More specifically, the objects whose status is checked in step S1 are the Z-axis moving device 6, the Y-axis moving device 7, the radial telescopic rod 3, the powder spraying gun 2, the laser 9, the friction wheel 4, the powder recovery chamber 11, and the negative pressure suction device 5.

[0013] More specifically, the pretreatment process in step S2 is as follows: 22# quartz sand is used to sandblast the surface of the rotor journal to be processed. The purpose of the pretreatment is to remove stains from the surface of the rotor journal to be processed, and at the same time increase the surface roughness, which is beneficial to the bonding between the powder and the matrix.

[0014] More specifically, in step S3, the particle size range of the low-Cr alloy powder is 25~60μm, and the powder shape is spherical or irregular; the carrier gas is nitrogen or helium, the carrier gas pressure is 4MPa, the preheating temperature is 800℃, and the powder feeding speed range of the powder spraying gun is 2~10r / min.

[0015] More specifically, in step S7, the powder recovered from the negative pressure suction port is processed by: vibrating sieving to remove impurities and excessively deformed particles.

[0016] The innovation of this invention lies in: utilizing a laser ranging device on the powder spray gun to achieve solid-state deposition in conjunction with the laser, enabling automated machine spraying. Compared to current welding and laser cladding technologies used for Cr reduction on rotor shaft surfaces, this method involves less heat input, avoids thermal damage to the rotor shaft surface, eliminates element diffusion, and achieves high Cr reduction efficiency. Simultaneous processing with powder spray guns and lasers on both sides of the rotor shaft ensures complete coverage, improves coating quality, and increases production efficiency. Before the rotor shaft is put into use, laser-assisted solid-state deposition technology is used to spray low-Cr content powder onto the rotor shaft surface to form a reinforced coating, improving the wear resistance of the high-Cr rotor shaft surface and extending its service life.

[0017] Compared with existing technologies, the beneficial effects of this invention are mainly reflected in: (1) The present invention provides an apparatus and method for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor. The apparatus is fully automated, greatly reducing manual intervention. Through "adaptive constant distance and constant angle" spraying, the uniformity and density of the coating on the journal surface are ensured, and the bonding strength is high. The coating quality is further improved by setting up a double-sided spraying system, and the spraying efficiency is greatly improved. It is especially suitable for mass production of reinforced coatings. (2) It overcomes the shortcomings of traditional low-Cr coating manufacturing methods, such as excessive thermal damage to the rotor journal surface and low Cr reduction efficiency. It can efficiently spray and manufacture low-Cr coatings on the rotor shaft surface, thereby enhancing the wear resistance of the high-Cr rotor shaft surface. (3) The powder recycling system increases the material utilization rate from the usual 50-70% to more than 95%, significantly reducing production costs and being green and environmentally friendly. At the same time, the semi-enclosed recycling chamber effectively curbs powder diffusion and protects the working environment and the health of operators.

[0018] (4) It can adapt to rotor journals of different diameters and lengths, and strengthen rotor journals of different diameters and lengths, resulting in high equipment utilization. Attached Figure Description

[0019] Figure 1 This is a structural diagram of the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor according to the present invention.

[0020] Figure 2 A front view of an apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor.

[0021] Figure 3 This is an internal structural diagram of a device used for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor.

[0022] Figure 4 This is a top view of an apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor.

[0023] Figure 5 This is a partial structural diagram of a spraying device used for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor.

[0024] Figure 6 The cross-sectional morphology of the 1CrMo coating prepared in Example 1 of this invention (image taken by scanning electron microscope, magnification 500x).

[0025] Figure 7 The image shows the cross-sectional morphology of the interface between the 1CrMo coating prepared in Example 1 of this invention and the HT700 substrate. The image was taken by scanning electron microscopy and the magnification is 1000x.

[0026] Figure 8 The surface scan results of Cr element at the interface between the 1CrMo coating prepared in Example 1 of this invention and the HT700 substrate are shown.

[0027] Figure 9 The image shows the Cr reduction effect of the 1CrMo coating prepared in Example 1 of this invention.

[0028] Figure 10 The results show the bonding strength test results between the 1CrMo coating prepared in Example 1 of this invention and the HT700 substrate.

[0029] Figure 11 This is a fracture result diagram of the bonding strength test between the 1CrMo coating prepared in Example 1 of the present invention and the HT700 substrate. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0031] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element 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.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0033] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0035] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0036] The present invention will now be described in detail with reference to the accompanying drawings and exemplary embodiments. Embodiment 1

[0037] This embodiment takes an HT700 high-temperature rotor shaft as an example to illustrate a process and apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor according to the present invention. The rotor shaft material is HT700 steel, and the shaft diameter of the machining area is 500mm.

[0038] The structure of an apparatus for implementing a Cr-reducing coating for the surface of a steam turbine rotor is as follows: Figure 1 As shown; it includes a frame 1, on which an arc-shaped rotor shaft processing channel is provided along the longitudinal direction. On the transverse sides of the rotor shaft processing channel, longitudinal Z-axis moving devices 6 are respectively provided. Y-axis moving devices 7 are respectively provided on the Z-axis moving devices 6. The Y-axis moving devices 7 can slide along the longitudinal direction of the Z-axis moving devices 6. Transverse radial telescopic rods 3 are respectively provided on the Y-axis moving devices 7. The radial telescopic rods 3 can slide up and down along the Y-axis moving devices 7. The ends of the two radial telescopic rods 3 facing each other are defined as processing ends. Each processing end of the radial telescopic rods 3 is equipped with a spraying device. The rotor shaft processing channel is provided with several semi-circular processing grooves 14 with spacing along the longitudinal direction. The top surface of the semi-circular processing groove 14 is provided with a friction wheel 4 that contacts the external rotor shaft 13. The space enclosed by the adjacent semi-circular processing grooves 14 and the bottom frame 1 is defined as the powder recovery chamber 11. The spraying device includes a swing mechanism 10 located inside the processing end of the radial telescopic rod 3, with a powder spray gun 2 and a laser 9 connected to the longitudinal sides of the swing mechanism 10, respectively.

[0039] The oscillating mechanism 10 includes a longitudinal rotating shaft 101, on which a driven gear 102 is fitted. The driven gear 102 meshes with an external drive mechanism 103. The two ends of the rotating shaft 101 are connected to a laser 9 and a powder spraying gun 2, respectively. By driving the worm gear 103 with a motor to drive the turbine 102, the powder spraying gun can oscillate adaptively, ensuring that the axis of the powder spraying gun is always aligned with the normal direction of the surface to be sprayed on the rotor shaft during the spraying process.

[0040] The laser 9 and the powder spraying gun 2 are connected to the swing mechanism 10 via a metal sleeve; the powder spraying gun 2 is perpendicular to the surface to be coated on the outer rotor shaft, and the powder spraying gun and the laser point to the same point on the rotor shaft surface within the rotor shaft processing channel. This ensures that the laser spot and the powder spraying spot coincide during operation.

[0041] The top of the frame 1 is equipped with a flexible wear-resistant cover 8, which together with the frame 1 forms a working space to accommodate the machining channel of the rotor shaft; the bottom of the powder recovery chamber 11 is provided with a negative pressure suction port 12, which is connected to a negative pressure suction machine 5.

[0042] The powder spraying gun 2 is equipped with a laser rangefinder to monitor and adjust the spraying distance in real time during the spraying process; the nozzle of the powder spraying gun 2 is a Laval nozzle, and the outlet shape of the Laval nozzle is circular.

[0043] The angle between the powder spray gun and the laser is 45°, and the powder spray gun nozzle maintains a processing distance of 30mm from the surface of the rotor shaft to be sprayed.

[0044] The working process of the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor is as follows: S1. The equipment used for manufacturing the Cr-reducing coating on the surface of the steam turbine rotor is started and its status is checked by the staff; S2. Pre-treat the surface of the rotor to be machined and place it in the rotor shaft machining channel; the rotor journal material is HT700; S3. Connect the powder feeder to the powder spraying gun 2, and load low-Cr alloy powder into the powder feeder. Set the relevant parameters, including carrier gas, carrier gas pressure, carrier gas preheating temperature, powder feeding rate, spraying gun moving speed, and laser power. The low-Cr alloy powder is 1CrMo metal powder with a particle size of 25-60μm. The carrier gas sprayed by the powder spraying gun 2 is nitrogen with a gas pressure of 4MPa, a carrier gas flow rate of 50ml / min, a preheating temperature of 800℃, a powder feeding speed of 6rpm, and a fiber-coupled semiconductor laser with a laser power of 800W. S4. Based on the outer diameter of the rotor shaft journal, adjust the powder sprayers on both sides of the rotor shaft to be perpendicular to the rotor shaft surface. Monitor the spraying distance in real time through the laser rangefinder arranged on the powder spraying gun, and maintain the preset spraying distance through feedback control. S5. Start the friction wheel 4 on the semi-circular working groove. The friction wheel 4 drives the rotor shaft 13 to rotate. S6. The equipment starts working. Laser 9 emits laser light to preheat the surface of the rotor shaft. Powder spraying gun 2 sprays low-Cr alloy powder. Laser 9 and powder spraying gun 2 on both sides of the rotor shaft 13 are synchronously driven by the Z-axis moving device 6. They start moving longitudinally from the spraying start point and form a spiral deposition trajectory on the surface of the rotating rotor shaft 13 to prepare the coating until the entire rotor shaft 13 is coated. The diameter of the powder spot sprayed by the powder spraying gun on the outer surface of the rotor shaft is 6mm. The radius of the laser spot emitted by the laser is 6mm. The laser spot and the powder spot always keep overlapping. During the spraying process, the powder sprayer and the laser move synchronously. At the same time, the negative pressure suction port 12 recovers the low-Cr alloy powder that falls into the powder recovery chamber 11. S7. After the spraying is completed, the coating is measured; the powder recovered by the negative pressure suction port 12 is processed and sent to the powder feeder for later use.

[0045] The coating thickness of rotor shaft 13 after the S7 reinforcement layer was sprayed was measured using metallographic methods. A sample with the coating was cut from the sprayed rotor shaft specimen. The sample was then sealed with phenolic resin as an insert for easy hand-held polishing. Metallographic sandpaper with grits of 80, 240, 500, 1000, and 2000 mesh was used to polish the sample cross-section sequentially until the surface was free of scratches. The polished sample was then observed and measured under a scanning electron microscope (SEM) to determine the thickness, with an average value of 2.5 mm. The obtained coating cross-section at 500x magnification is shown below. Figure 6 As shown, the porosity of the coating was measured in different areas using ImageJ software, and the average value was calculated to be 0.09%. Compared with cold spraying, which is difficult to obtain a low-chromium coating (1CrMo coating) on ​​the substrate material (HT700 steel), this result shows that the process method and apparatus of this embodiment have a more efficient deposition effect.

[0046] The above-prepared sample was analyzed for Cr elemental content using scanning electron microscopy and energy dispersive spectroscopy (EDS). The test area is shown in the figure. Figure 7 As shown, with the HT700 substrate at the bottom (approximately 700 μm from the bonding interface) and the sprayed coating at the top (approximately 850 μm from the bonding interface), the change in Cr content from the substrate to the coating was measured using a line scan method. The test results are as follows. Figure 8 and Figure 9 As shown, the Cr element is rapidly reduced at the interface, achieving the requirements for a low-chromium surface layer at the μm level. In contrast, laser cladding requires a 5mm cladding layer thickness to achieve the same low-chromium surface layer effect as laser cladding on the substrate material. This result demonstrates that the surface Cr reduction effect of this embodiment is more efficient.

[0047] The coating-substrate bond was tested using an Inston 5967 electronic universal testing machine. Bond strength was tested using an adhesive method on three bonded specimens, and the results are as follows: Figure 10As shown, the fracture mode was adhesive fracture in all cases, and the bond strength was greater than 80 MPa. In comparison, the bond strength of cold-sprayed coatings under normal conditions is 30-40 MPa. This result demonstrates that the coating in this embodiment has a higher interfacial bond strength with the substrate.

[0048] Finally, a low-chromium coating with a thickness of 2.5 mm, dense (porosity < 0.1%), and well bonded to the rotor shaft surface substrate was obtained, with a bonding strength greater than 80 MPa.

Claims

1. An apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor, characterized in that: Includes a frame (1), on which a circular arc-shaped rotor shaft processing channel is provided along the longitudinal direction. On the transverse sides of the rotor shaft processing channel, longitudinal Z-axis moving devices (6) are provided respectively. On the Z-axis moving devices (6), Y-axis moving devices (7) are provided respectively. The Y-axis moving devices (7) can slide longitudinally along the Z-axis moving devices (6). On the Y-axis moving devices (7), transverse radial telescopic rods (3) are provided respectively. The radial telescopic rods (3) can slide up and down along the Y-axis moving devices (7). The ends of the two radial telescopic rods (3) facing each other are defined as processing ends. The processing ends of the radial telescopic rods (3) are each provided with a spraying device. The rotor shaft machining channel is provided with several semi-circular machining grooves (14) with a spacing along the longitudinal direction. The top surface of the semi-circular machining groove (14) is provided with a friction wheel (4) that contacts the external rotor shaft (13). The space enclosed by the adjacent semi-circular machining grooves (14) and the bottom frame (1) is defined as the powder recovery chamber (11). The spraying device includes a swing mechanism (10) located inside the processing end of the radial telescopic rod (3), and a powder spraying gun (2) and a laser (9) are respectively connected to the longitudinal sides of the swing mechanism (10).

2. The apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor according to claim 1, characterized in that: The swing mechanism (10) includes a longitudinal rotating shaft (101), on which a turbine (102) is sleeved, and the turbine (102) meshes with a worm gear (103) connected to an external motor; the two ends of the rotating shaft (101) are respectively connected to a laser (9) and a powder spraying gun (2).

3. The apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor according to claim 1, characterized in that: The laser (9) and the powder spraying gun (2) are connected to the swing mechanism (10) via a metal sleeve; the powder spraying gun (2) is perpendicular to the surface to be sprayed on the outer rotor shaft (13), and the powder spraying gun (2) and the laser (9) point to the same point on the rotor shaft surface within the rotor shaft processing channel.

4. The apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor according to claim 1, characterized in that: The top of the frame (1) is equipped with a flexible wear-resistant cover (8), which together with the frame (1) forms a working space to accommodate the machining channel of the rotor shaft; the bottom of the powder recovery chamber (11) is provided with a negative pressure suction port (12), which is connected to a negative pressure suction machine (5).

5. The apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor according to claim 1, characterized in that: The powder spraying gun (2) is equipped with a laser rangefinder to monitor and adjust the spraying distance in real time during the spraying process; the nozzle of the powder spraying gun (2) is a Laval nozzle, and the outlet shape of the Laval nozzle is circular.

6. A method of using the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor as described in claim 1, comprising the following steps: S1. The equipment used for manufacturing the Cr-reducing coating on the surface of the steam turbine rotor is started and its status is checked by the staff; S2. Pre-treat the surface of the rotor to be machined and place it in the rotor shaft machining channel; S3. Connect the powder feeder to the powder spraying gun, load low-Cr alloy powder into the powder feeder, and set relevant parameters, including carrier gas, carrier gas pressure, carrier gas preheating temperature, powder feeding rate, spraying gun moving speed and laser power. S4. According to the outer diameter of the rotor shaft journal, adjust the powder spraying guns (2) on both sides of the rotor shaft (13) to be perpendicular to the rotor shaft surface. The spraying distance is monitored in real time by the laser rangefinder arranged on the powder spraying gun, and the preset spraying distance is maintained by feedback control. S5. Start the friction wheel (4) on the semi-circular working groove. The friction wheel (4) drives the rotor shaft (13) to rotate. S6. The equipment starts working. The laser (9) emits laser to preheat the surface of the rotor shaft. The powder spraying gun (2) sprays low-Cr alloy powder. The laser (9) and the powder spraying gun (2) on both sides of the rotor shaft (13) are synchronously driven by the Z-axis moving device (6) and start to move longitudinally from the spraying start point. A spiral deposition trajectory is formed on the surface of the rotating rotor shaft (13) to prepare the coating until the entire rotor shaft (13) is sprayed. At the same time, the negative pressure suction port (12) recovers the low-Cr alloy powder that falls into the powder recovery chamber (11). S7. After the coating is completed, the coating is measured; the powder recovered by the negative pressure suction port (12) is processed and sent to the powder feeder for later use.

7. The method of using the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor as described in claim 6, characterized in that: The objects whose status is checked in step S1 are the Z-axis moving device (6), the Y-axis moving device (7), the radial telescopic rod (3), the powder spraying gun (2), the laser (9), the friction wheel (4), the powder recovery chamber (11), and the negative pressure suction device (5).

8. The method of using the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor as described in claim 6, characterized in that, The pretreatment process in step S2 is as follows: the surface of the rotor journal to be processed is sandblasted using 22# quartz sand.

9. The method of using the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor as described in claim 6, characterized in that: In step S3, the particle size range of the low-Cr alloy powder is 25~60μm, and the powder shape is spherical or irregular; the carrier gas is nitrogen or helium, the carrier gas pressure is 4MPa, the preheating temperature is 800℃, and the powder feeding speed range of the powder spraying gun is 2~10r / min.

10. The method of using the apparatus for manufacturing a Cr-reducing coating on the surface of a steam turbine rotor as described in claim 6, characterized in that, In step S7, the powder recovered from the negative pressure suction port is processed by: vibrating sieving to remove impurities and excessively deformed particles.

Images