Clamp for bearing outer ring coating preparation, spraying process and spray gun trajectory optimization method

Abstract

The present application belongs to the field of coating preparation, and particularly relates to a clamp for bearing outer ring coating preparation, a spraying process and a spraying gun trajectory optimization method. The clamp for bearing outer ring coating preparation is a split expandable clamp, and the pre-tightening force of the long neck bolt and the nut is used to ensure that the split clamp is tightly matched with the inner circumferential surface of the bearing outer ring to support the movement of the bearing outer ring. The spraying process procedure includes bearing outer ring cleaning treatment, bearing outer ring clamping and protection, surface roughening treatment, coating preparation and clamp disassembly. The spraying gun trajectory optimization method includes two processes of obtaining the space distribution curve of the deposition particle characteristic parameters and optimizing the space path planning and trajectory for the bearing outer ring surface through experiments. Through the above measures, the uniformity, compactness and efficiency of the bearing outer ring coating preparation can be improved, the coating on the bearing outer ring surface can be prepared at low cost and high efficiency, and the internal organization and size precision of the coating can be accurately controlled.

Description

Technical Field

[0001] This invention belongs to the field of coating preparation, specifically relating to a fixture for preparing a bearing outer ring coating, a spraying process, and a method for optimizing the spray gun trajectory. Background Technology

[0002] With the advancement of wind power generation and variable frequency motor technology, bearings used in motors or generators are experiencing premature failure due to electrolytic corrosion caused by high-frequency currents. Currently, preparing an insulating coating on the outer ring of the bearing can effectively protect it. During the preparation of the thermal spray coating on the outer ring, multiple planes of the outer ring need to be sprayed, and the raceway needs to be protected simultaneously. Therefore, a good outer ring clamping method can comprehensively ensure the quality of the outer ring coating preparation.

[0003] Currently, bearing outer ring spraying clamping methods include stepped shaft clamping and mechanical clamping of the outer circumferential surface. Stepped shaft clamping requires pressing the bearing outer ring into a stepped shaft for fixation, which easily damages the inner surface of the outer ring and makes installation and disassembly difficult. Mechanical clamping of the outer circumferential surface requires individual spraying on each surface of the bearing outer ring, which can easily cause a loose structure at the coating overlap in the transition area, making it prone to electrical breakdown in practical applications. Considering the problems existing in current bearing outer ring thermal spraying clamping methods, there is an urgent need for a high-efficiency, low-cost clamping method that is easy to install and disassemble, provides good raceway protection, ensures stable rotational support, and allows for continuous coating preparation.

[0004] Furthermore, in the practice of spraying coatings on the outer ring of bearings, it was found that when preparing coatings on the outer ring surface via thermal spraying, the spray spot size (approximately 10 mm) is larger than the minimum radial dimension of the bearing end face. This results in non-perfectly vertical deposition of flying particles on the outer ring surface during spraying, making it difficult to precisely control the coating thickness and microstructure. In practice, the spray deposition area is often increased to achieve complete coverage, leading to significant resource waste and low coating quality. Therefore, a method for optimizing the spray gun's motion trajectory is needed to optimize the spray gun's motion parameters and comprehensively improve the coating quality on the bearing outer ring surface. Summary of the Invention

[0005] The purpose of this invention is to provide a fixture, spraying process, and spray gun trajectory optimization method for preparing a bearing outer ring coating. Through a series of measures, a coating can be prepared on the surface of the bearing outer ring with high efficiency and high quality. This invention can achieve low-cost and high-efficiency preparation of a coating on the surface of the bearing outer ring, and can accurately control the internal structure and dimensional accuracy of the coating.

[0006] The technical solution of this invention is:

[0007] A fixture for preparing a bearing outer ring coating includes a split fixture, a first annular component with a conical surface, a second annular component with a conical surface, a long neck bolt with a through hole, and a nut. The specific structure is as follows:

[0008] The split clamp is a combination structure of three identical 120° sector units. The combination structure includes an outer ring, a spoke plate, and an inner ring. The outer ring and the inner ring are connected by the spoke plate. Both the inner ring and the outer ring are annular cylinders and are arranged along the inner and outer coaxial lines. The spoke plate is a horizontally arranged annular plate located in the middle between the inner ring and the outer ring. The inner wall of the center hole of the inner ring is a structure with two symmetrical frustum-shaped first inner cone surfaces and second inner cone surfaces. The middle diameter of this mating structure is smaller than the diameters at both ends. The upper end is provided with a first annular component with a cone surface, and the lower end is provided with a second annular component with a cone surface.

[0009] The periphery of the first annular component with a conical surface matches the first inner conical surface through the first outer conical surface, and the periphery of the second annular component with a conical surface matches the second inner conical surface through the second outer conical surface; the first central threaded hole of the first annular component with a conical surface and the second central threaded hole of the second annular component with a conical surface have the same diameter and are vertically aligned; a long-neck bolt with a through hole is sequentially inserted into the first central threaded hole and the second central threaded hole, and its protruding end is fastened by a nut.

[0010] The aforementioned jig for preparing the outer ring coating of the bearing has a split jig with an outer diameter smaller than the inner diameter of the bearing outer ring. It is placed completely inside the bearing outer ring and is divided into three equal parts with the center as the base point. Under the action of external mechanical force, this split jig expands outward to make close contact with the inner surface of the bearing outer ring. After the split jig is placed into the bearing outer ring, a first annular component with a conical surface and a second annular component with a conical surface are symmetrically placed into the first inner conical surface and the second inner conical surface of the split jig. Then, a long neck bolt with a through hole is inserted into the first annular component and the second annular component. One end of the long neck bolt has a shoulder with a radial dimension larger than the diameter of the first central threaded hole of the annular component, and the other end is a threaded section that mates with a nut. The nut that mates with the long neck bolt is installed on the threaded section of the long neck bolt.

[0011] The aforementioned fixture for preparing the outer ring coating of the bearing has the following clamping method: applying a preload to the long neck bolt and nut to ensure a tight fit between the outer ring of the split fixture and the inner circumferential surface of the bearing outer ring; the relative rotational motion of the long neck bolt and nut is converted into an axial approaching motion of the symmetrically assembled first and second annular components; and the axial approaching motion of the first and second annular components is converted into a radial expansion motion of the split fixture due to the expandability of the split fixture.

[0012] A spraying process using the aforementioned fixture for preparing a bearing outer ring coating includes: cleaning the bearing outer ring surface, clamping and protecting the bearing outer ring, roughening the bearing outer ring surface, preparing the bearing outer ring surface coating, and disassembling the fixture. The specific steps are as follows:

[0013] (1) Bearing outer ring cleaning treatment: Use anhydrous ethanol or acetone to clean the grease and dirt from the bearing outer ring to ensure that the overall surface of the bearing outer ring is clean before sandblasting;

[0014] (2) Clamping and protection of bearing outer ring: The bearing outer ring is tightly clamped using the clamping method of the fixture for preparing bearing outer ring coating;

[0015] (3) Roughening treatment of bearing outer ring surface: Sandblasting is performed on the outer peripheral surface, two axial end faces, the transition area between the outer peripheral surface and the two axial end faces, and the transition area between the two axial end faces and the inner peripheral surface of the bearing outer ring. High pressure gas is used to remove residual sand particles from the surface after sandblasting roughening.

[0016] (4) Preparation of coating on bearing outer ring surface: The bearing outer ring together with the bearing outer ring coating preparation fixture is mounted on the rotating shaft and kept rotating. At the same time, the robot arm is adjusted to move according to the outer ring contour proportionally and keep the spray gun perpendicular to the spraying surface. The coordinated action of the outer ring rotation and the robot arm curve movement ensures that the spray gun continuously sprays the bearing outer ring surface.

[0017] (5) Fixture disassembly: After the spraying is completed, the clamping fixture is separated from the outer ring of the bearing.

[0018] In step (2), the contact area between the fixture for preparing the outer ring coating of the bearing and the inner circumferential surface of the outer ring of the bearing is protected by a soft metal foil of the same width.

[0019] In step (4), the temperature of the bearing outer ring is controlled by applying cooling measures and controlling the dwell time between spray passes during the spraying process, and the coating thickness is uniformly and symmetrically distributed by changing the orientation of the bearing outer ring.

[0020] In step (5), first separate the long-neck bolt and nut, then disassemble the first ring component and the second ring component, and finally disassemble the split clamp.

[0021] A method for optimizing the spray gun trajectory in the aforementioned spraying process includes the following steps:

[0022] The first step is to obtain the spatial distribution curves of the characteristic parameters of the deposited particles through experiments;

[0023] The second step involves spatial path planning and trajectory optimization for the outer ring surface of the bearing.

[0024] In the first step, a thermally sprayed deposition coating is first applied to a flat substrate. This deposition method is either fixed-point long-term spraying or multi-pass spraying along a line. Then, the cross-section of the deposition layer is observed using a metallographic microscope or a scanning electron microscope to measure the characteristic parameters of the deposition layer thickness and porosity at different locations. The characteristic parameters obtained at different locations are used to fit the spatial coordinates to obtain the curves of the characteristic parameters as a function of spatial location.

[0025] In the second step, the spray gun trajectory is optimized in simulation software by combining the specific bearing outer ring surface contour features and the spatial distribution curve of the deposition particle characteristic parameters. The geometric parameters of the bearing outer ring surface and the spatial distribution curve of the characteristic parameters obtained under different deposition conditions are used as input parameters. The coating thickness uniformity and the minimum coating porosity are used as the final optimization objectives. Numerical simulation is performed in computer software to coordinate the optimization of the spray gun trajectory, speed, acceleration and relative approximation ratio.

[0026] The design concept of this invention is:

[0027] For the preparation technology of bearing outer ring surface coating, a split-type expandable fixture scheme for supporting and protecting the bearing outer ring is first proposed. Then, a coating preparation process specification including the movement mode of the bearing outer ring and the spray gun is proposed for this fixture scheme. Finally, in order to improve the density, uniformity and preparation efficiency of the outer ring coating structure, a spray gun trajectory optimization method is proposed. Through the above three steps, the overall quality of bearing outer ring surface coating preparation can be improved.

[0028] The advantages and beneficial effects of this invention are:

[0029] The fixture of this invention is a split, expandable fixture. The preload of the long-neck bolts and nuts ensures a tight fit between the split fixture and the inner circumferential surface of the bearing outer ring, supporting the movement of the bearing outer ring. The spraying process of this invention includes cleaning the bearing outer ring, clamping and protecting the bearing outer ring, surface roughening treatment, coating preparation, and fixture disassembly. The spray gun trajectory optimization method of this invention includes two processes: obtaining the spatial distribution curve of the deposition particle characteristic parameters through experiments and spatial path planning and trajectory optimization for the bearing outer ring surface. Through the above measures of this invention, the uniformity, density, and efficiency of bearing outer ring coating preparation can be improved. Attached Figure Description

[0030] Figure 1 Front view of the fixture used for preparing the outer ring coating of the bearing.

[0031] Figure 2 for Figure 1 Top view of the split-type clamp 1.

[0032] Figures 1-2 Reference numerals in the attached drawings: 1 Split clamp (including outer ring 1a, spoke 1b, inner ring 1c, first inner conical surface 1d, second inner conical surface 1e), 2 First annular component (including first outer conical surface 2a, first central threaded hole 2b), 3 Second annular component (including second outer conical surface 3a, second central threaded hole 3b), 4 Long neck bolt, 5 Nut.

[0033] Figure 3This is a curve showing the thickness distribution of the vertically deposited layer in thermal spraying as a function of radial dimensions.

[0034] Figure 4 The curve shows the distribution of thickness of the inclined thermal spray deposition layer as a function of radial dimension. Detailed Implementation

[0035] In its specific implementation, this invention proposes a fixture for preparing a bearing outer ring coating. The principle is that the split fixture 1 expands outward under mechanical action to support the rotating component and protect the non-coated surface. For example... Figures 1-2 As shown, the fixture for preparing the outer ring coating of the bearing mainly includes: a split fixture 1, a first annular component with a conical surface 2, a second annular component with a conical surface 3, a long neck bolt with a through hole 4, a nut 5, etc., with the specific structure as follows:

[0036] The split clamp 1 is a combination structure of three identical 120° sector units. The combination structure includes an outer ring 1a, a spoke plate 1b, and an inner ring 1c. The outer ring 1a and the inner ring 1c are connected by the spoke plate 1b. The inner ring 1c and the outer ring 1a are both annular cylinders and are arranged along the inner and outer coaxial lines. The spoke plate 1b is a horizontally arranged annular plate and is located in the middle between the inner ring 1c and the outer ring 1a. The inner wall of the central hole of the inner ring 1c is a docking structure of two symmetrical frustum-shaped first inner conical surfaces 1d and second inner conical surfaces 1e. The middle diameter of the docking structure is smaller than the diameters at both ends. The upper end is provided with a first annular member 2 with a conical surface, and the lower end is provided with a second annular member 3 with a conical surface.

[0037] The outer periphery of the first annular member 2 with a conical surface is matched with the first inner conical surface 1d through the first outer conical surface 2a, and the outer periphery of the second annular member 3 with a conical surface is matched with the second inner conical surface 1e through the second outer conical surface 3a. The first central threaded hole 2b of the first annular member 2 with a conical surface and the second central threaded hole 3b of the second annular member 3 with a conical surface have the same diameter and are corresponding vertically. The long neck bolt 4 with a through hole is sequentially inserted into the two threaded holes (the first central threaded hole 2b and the second central threaded hole 3b), and its protruding end is fastened by a nut 5.

[0038] like Figure 2 As shown, the outer diameter of the split clamp 1 is slightly smaller than the inner diameter of the bearing outer ring by 2-4 mm, allowing it to be completely placed inside the bearing outer ring. Divided into three equal parts with the center as the base point, this split clamp can expand outwards under applied mechanical force until it is in close contact with the inner surface of the bearing outer ring. Figure 2In the process, after the split clamp 1 is placed into the outer ring of the bearing, the first annular member 2 with a conical surface and the second annular member 3 with a conical surface are symmetrically placed into the first inner conical surface 1d and the second inner conical surface 1e of the split clamp 1. Then, a long neck bolt 4 with a through hole is inserted into the first annular member 2 and the second annular member 3. One end of the long neck bolt 4 has a shoulder with a radial dimension larger than the inner diameter of the annular member, and the other end is a threaded section that mates with a nut 5. The nut 5 is installed on the threaded section of the long neck bolt 4.

[0039] The clamping method of the fixture for preparing the bearing outer ring coating is as follows: the relative rotational motion of the long neck bolt 4 and nut 5 is transformed into the axial approaching motion of the symmetrically assembled first annular component 2 and second annular component 3. Due to the presence of the conical end faces 1d and 1e and the expandability of the split fixture 1, the axial approaching motion of the first annular component 2 and second annular component 3 is transformed into the radial expansion motion of the split fixture 1. Finally, the residual elastic stress of the long neck bolt 4 and nut 5 ensures the friction between the outer circumferential surface of the split fixture 1 and the inner circumferential surface of the bearing outer ring, thereby stably supporting the rotational motion of the bearing outer ring and effectively protecting the inner rolling surface of the bearing outer ring.

[0040] The clamping method described in this invention for supporting the rotation of the bearing outer ring has the following characteristics:

[0041] (1) The split fixture applies a uniform clamping force that is centrally symmetrical to the inner circumferential surface of the bearing outer ring, avoiding deformation caused by uneven force on the bearing outer ring; at the same time, during the spraying process of the bearing outer ring, the split fixture can stably support the bearing outer ring to rotate, and the excellent rotational centering ensures the uniformity of the coating thickness and the compactness of the structure on the bearing outer ring surface.

[0042] (2) The split fixture can be flexibly disassembled and reused multiple times, reducing production costs and increasing production efficiency.

[0043] (3) The split fixture causes minimal damage to the bearing outer ring. Due to the tight fit between the split fixture and the inner circumferential surface of the bearing outer ring, effective protection of the bearing outer ring raceway surface is ensured, preventing powder particles from entering the inner raceway area during thermal spraying and sandblasting roughening processes, thus avoiding damage to the raceway surface and reducing the overall fatigue life of the bearing.

[0044] (4) The split fixture causes minimal damage to the thermal spray coating. The height of the split fixture is the same as the axial width of the inner circumferential surface of the bearing outer ring, ensuring that the transition area between the inner circumferential surface of the bearing outer ring and the two axial end faces can be effectively sprayed during the thermal spraying process, and the fixture disassembly operation after spraying does not damage the coating in the transition area.

[0045] This invention also proposes a spraying process, the purpose of which is to prepare a coating on the outer ring surface of a bearing with high efficiency, high quality, and high precision. The coating preparation process is as follows:

[0046] (1) Cleaning treatment of bearing outer ring: Use anhydrous ethanol or acetone to clean the grease and dirt on the bearing outer ring to ensure that the overall surface of the bearing outer ring is clean before sandblasting.

[0047] (2) Clamping and protection of bearing outer ring: The bearing outer ring is tightly clamped using a fixture for preparing bearing outer ring coating.

[0048] Preferably, the contact area between the fixture for preparing the outer ring coating of the bearing and the inner circumferential surface of the outer ring is protected by a soft metal foil of the same width, such as aluminum foil or copper foil.

[0049] (3) Roughening treatment of bearing outer ring surface: Sandblasting is performed on the outer circumferential surface, the two axial end faces, the transition area between the outer circumferential surface and the two axial end faces, and the transition area between the two axial end faces and the inner circumferential surface of the bearing outer ring. High pressure gas is used to remove residual sand particles from the surface after sandblasting roughening.

[0050] (4) Coating preparation on the outer ring surface of the bearing: The outer ring of the bearing, together with the clamping fixture, is mounted on the rotating shaft and kept in rotation. At the same time, the robot arm is adjusted to move in a proportionally enlarged curve according to the outer ring contour, and the spray gun is kept perpendicular to the spraying surface. The coordinated action of the outer ring rotation and the robot arm curve movement ensures that the spray gun continuously sprays the outer ring surface of the bearing.

[0051] Preferably, the bearing outer ring temperature is controlled during the spraying process by applying cooling measures and controlling the dwell time between spray passes. To maximize the uniformity of the coating thickness, the bearing orientation can be reversed to ensure a symmetrical and uniform thickness distribution.

[0052] (5) Fixture disassembly: After the coating is applied, the fixture used for preparing the outer ring coating of the bearing is separated from the outer ring of the bearing.

[0053] This invention also proposes a spray gun trajectory optimization method, the purpose of which is to achieve highly uniform, highly dense, and highly efficient coating deposition on the outer ring surface of the bearing by optimizing the spray gun movement trajectory during the spraying process. This spray gun trajectory optimization method includes two processes:

[0054] (1) The spatial distribution curve of the characteristic parameters of the deposited particles was obtained through experiments. First, a thermally sprayed deposition coating was applied to a smooth substrate. This deposition method included fixed-point long-term spraying and multi-pass spraying along a line. Then, the cross-section of the deposition layer was observed using metallography or scanning electron microscopy to measure characteristic parameters such as the thickness and porosity of the deposition layer at different locations. The characteristic parameters obtained at different locations were used to fit the spatial coordinates to obtain the curves showing the variation of the characteristic parameters with spatial location. Preferably, a three-dimensional scanner was used to scan the surface contour of the deposition layer to obtain the geometric distribution characteristic curve of the deposition layer. Figure 3 and Figure 4 As shown, in the experiment, the spatial distribution curves of characteristic parameters can be obtained by analyzing the sedimentary layers obtained at different deposition rates and deposition angles.

[0055] (2) Spatial path planning and trajectory optimization for the bearing outer ring surface. The spray gun trajectory is optimized in simulation software (e.g., ANSYS, MATLAB) by combining the specific bearing outer ring surface characteristics with the spatial distribution curves of the deposition particle characteristic parameters. Specifically, the spatial distribution curves of the characteristic parameters obtained under different deposition conditions are used as input parameters, with the goal of maximizing coating thickness uniformity or minimizing coating porosity. Numerical simulation is performed in computer software to collaboratively optimize parameters such as spray gun trajectory, speed, acceleration, and relative approximation ratio to achieve the set coating thickness uniformity or porosity targets.

[0056] The spray gun trajectory optimization method of the present invention has the following characteristics:

[0057] (1) It can achieve uniformity in the preparation of coatings on the surface of small-sized devices. The spray gun trajectory is optimized according to the geometric features of different device structures and the spatial distribution curve of the deposition layer thickness to obtain the maximum thickness uniformity.

[0058] (2) It can achieve high density in the preparation of coatings on the surface of small-sized devices. The spray gun trajectory is optimized based on the geometric features of different device structures and the spatial distribution curve of the density of the deposited layer to obtain a high-density coating.

[0059] (3) It can achieve high efficiency in the preparation of coatings on the surface of small-sized devices. Compared with expanding the spray deposition area to obtain a full-coverage coating, the optimized spray gun movement mode increases the accuracy of the deposition position and reduces the coating preparation time and cost.

[0060] The present invention will be further described in detail below through embodiments.

[0061] Example

[0062] In this embodiment, a coating is prepared on the outer ring surface (including the outer circumferential surface of the bearing outer ring, the two axial end faces of the bearing outer ring, and the transition area) of a deep groove ball bearing of model 6215. The purpose of this invention is to provide an implementation example, but the content of this invention is not limited to a certain bearing model.

[0063] To efficiently and effectively prepare a dense and uniform insulating coating on the outer ring surface of bearing model 6215, the following process procedure was adopted:

[0064] Bearing outer ring surface cleaning: During storage and transportation, the bearing outer ring is generally coated with protective lubricating oil to prevent surface corrosion. Before applying the coating, the outer ring should be wiped with anhydrous ethanol to remove grease and dirt.

[0065] Bearing outer ring clamping: such as Figures 1-2 As shown, a fixture for preparing the outer ring coating of this type of bearing was designed. Before radial expansion, the outer diameter of the split fixture 1 is 110 mm, slightly smaller than the inner diameter of the bearing outer ring (113.5 mm), to facilitate the insertion of a 0.5 mm thick copper strip during clamping. The copper strip serves to prevent sand particles and spray powder from entering the bearing outer ring raceway during sandblasting and spraying, causing raceway scratches. The width of the split fixture 1 is 23.16 mm, the same as the width of the inner circumferential surface of the bearing outer ring after removing the chamfer dimension, thus ensuring effective coating deposition on the transition area between the two end faces and the inner circumferential surface of the bearing during spraying. During clamping, the copper strip and the split fixture 1 are first placed inside the bearing outer ring, then the first annular member 2 and the second annular member 3 are symmetrically placed into the conical surface that mates with the split fixture 1, and then the long neck bolt 4 is inserted into the first annular member 2 and the second annular member 3, and the fit is tightened with a nut 5. Applying a preload to the long neck bolt 4 and nut 5 ensures that the outer surface of the split clamp 1 fits tightly against the inner circumferential surface of the bearing outer ring.

[0066] Sandblasting treatment of the bearing outer ring surface: The clamped bearing outer ring is placed in a sandblasting chamber for sandblasting. The sandblasted surfaces include the outer circumferential surface of the bearing outer ring, the two axial end faces, the transition area between the outer circumferential surface and the two axial end faces, and the transition area between the two axial end faces and the inner circumferential surface. 30-mesh white corundum abrasive is selected, the sandblasting pressure is 0.8 MPa, and the angle is 80°. After sandblasting, the surface roughness Ra = 20 μm. Subsequently, high-pressure air is used to blow away any remaining abrasive particles from the bearing outer ring surface.

[0067] Coating preparation on the bearing outer ring surface: The sandblasted bearing outer ring, along with the bearing outer ring coating preparation fixture, is mounted on a lathe rotating shaft at a speed of 80 r / min. An alumina insulating coating is prepared on the bearing outer ring surface using atmospheric plasma spraying technology. During the spraying process, the movement trajectory of the spray gun held by the robotic arm is controlled to deposit the coating on all exposed surfaces of the bearing outer ring. High-pressure flowing gas is used to cool the bearing outer ring surface, maintaining the bearing outer ring temperature below 120℃ during coating deposition. Excessively high deposition temperatures can cause annealing of the bearing steel substrate, thus affecting its mechanical strength.

[0068] Fixture disassembly: First, open the mating long neck bolt 4 and nut 5, remove the first ring component 2 and the second ring component 3, and finally separate the split fixture 1 from the outer ring of the bearing.

[0069] In subsequent experiments, the cross-section of the bearing outer ring with the sprayed coating was observed using scanning electron microscopy. The coating thickness and porosity at different locations on the bearing outer ring were observed. To achieve uniformity and density of the coating thickness, the spray gun motion parameters were adjusted using a spray gun trajectory optimization method.

Claims

1. A fixture for preparing a coating on the outer ring of a bearing, characterized in that, It includes a split clamp (1), a first annular component with a conical surface (2), a second annular component with a conical surface (3), a long neck bolt with a through hole (4), and a nut (5), with the following specific structure: The split clamp (1) is a combination structure of three identical 120° sector units. The combination structure includes an outer ring (1a), a spoke plate (1b), and an inner ring (1c). The outer ring (1a) and the inner ring (1c) are connected by the spoke plate (1b). The inner ring (1c) and the outer ring (1a) are both annular cylinders and are arranged along the inner and outer coaxial lines. The spoke plate (1b) is a horizontally arranged annular plate and is located in the middle between the inner ring (1c) and the outer ring (1a). The inner wall of the center hole of the inner ring (1c) is a docking structure of two symmetrical frustum-shaped first inner cone surface (1d) and second inner cone surface (1e). The middle diameter of the docking structure is smaller than the diameters at both ends. The upper end is provided with a first annular component (2) with a cone surface, and the lower end is provided with a second annular component (3) with a cone surface. The periphery of the first annular member (2) with a conical surface is matched with the first inner conical surface (1d) through the first outer conical surface (2a), and the periphery of the second annular member (3) with a conical surface is matched with the second inner conical surface (1e) through the second outer conical surface (3a); the first central threaded hole (2b) of the first annular member (2) with a conical surface and the second central threaded hole (3b) of the second annular member (3) with a conical surface have the same diameter and are corresponding vertically; the long neck bolt (4) with a through hole is sequentially inserted into the first central threaded hole (2b) and the second central threaded hole (3b), and its protruding end is fastened by a nut (5); The outer diameter of the split clamp is smaller than the inner diameter of the bearing outer ring, and it is completely placed inside the bearing outer ring. It is divided into three equal parts with the center as the base point. Under the action of external mechanical force, this split clamp expands outward to make close contact with the inner surface of the bearing outer ring. After the split clamp is placed into the bearing outer ring, the first annular component (2) with a conical surface and the second annular component (3) with a conical surface are symmetrically placed into the first inner conical surface (1d) and the second inner conical surface (1e) of the split clamp (1). Then, the long neck bolt (4) with a through hole is inserted into the first annular component (2) and the second annular component (3). One end of the long neck bolt has a shoulder with a radial dimension larger than the diameter of the first central threaded hole (2b) of the annular component, and the other end is a threaded section that mates with the nut (5). The nut (5) that mates with the long neck bolt (4) is installed on the threaded section of the long neck bolt (4). The clamping method of the fixture is as follows: a preload is applied to the long neck bolt (4) and the nut (5) so that the outer ring (1a) of the split fixture (1) is tightly fitted with the inner circumferential surface of the outer ring of the bearing. The relative rotational motion of the long neck bolt (4) and the nut (5) is transformed into the axial approaching motion of the symmetrically assembled first ring component (2) and second ring component (3). Through the expandability of the split fixture, the axial approaching motion of the first ring component (2) and the second ring component (3) is transformed into the radial expansion motion of the split fixture (1).

2. A spraying process using the fixture of claim 1, characterized in that, The process includes cleaning the bearing outer ring surface, clamping and protecting the bearing outer ring, roughening the bearing outer ring surface, preparing the bearing outer ring surface coating, and disassembling the fixture. The specific steps are as follows: (1) Bearing outer ring cleaning treatment: Use anhydrous ethanol or acetone to clean the grease and dirt on the bearing outer ring to ensure that the overall surface of the bearing outer ring is clean before sandblasting; (2) Clamping and protection of the bearing outer ring: The bearing outer ring is tightly clamped using the clamping method described above; (3) Roughening treatment of bearing outer ring surface: Sandblasting is performed on the outer peripheral surface, two axial end faces, the transition area between the outer peripheral surface and the two axial end faces, and the transition area between the two axial end faces and the inner peripheral surface of the bearing outer ring. High pressure gas is used to remove residual sand particles from the surface after sandblasting roughening. (4) Preparation of coating on the outer ring of bearing: The outer ring of bearing is mounted on the rotating shaft together with the fixture and kept rotating. At the same time, the robot arm is adjusted to move according to the outer ring contour proportionally and keep the spray gun perpendicular to the spraying surface. The coordinated action of the outer ring rotation and the robot arm curve movement ensures that the spray gun continuously sprays the outer ring surface of the bearing. (5) Fixture disassembly: After the spraying is completed, the clamping fixture is separated from the outer ring of the bearing.

3. The spraying process of the fixture according to claim 2, characterized in that, In step (2), the contact area between the fixture for preparing the outer ring coating of the bearing and the inner circumferential surface of the outer ring of the bearing is protected by a soft metal foil of the same width.

4. The spraying process of the fixture according to claim 2, characterized in that, In step (4), the temperature of the bearing outer ring is controlled by applying cooling measures and controlling the dwell time between spraying passes during the spraying process, and the coating thickness is uniformly and symmetrically distributed by changing the orientation of the bearing outer ring.

5. The spraying process of the fixture according to claim 2, characterized in that, In step (5), first separate the long neck bolt and nut, then disassemble the first ring component and the second ring component, and finally disassemble the split clamp.

6. A method for optimizing the spray gun trajectory in the spraying process of claim 2, characterized in that, Includes the following steps: The first step is to obtain the spatial distribution curves of the characteristic parameters of the deposited particles through experiments; The second step involves spatial path planning and trajectory optimization for the outer ring surface of the bearing.

7. The spray gun trajectory optimization method according to claim 6, characterized in that, In the first step, a thermally sprayed deposition coating is first applied to a flat substrate. This deposition method is either fixed-point long-term spraying or multi-pass spraying along a line. Then, the cross-section of the deposition layer is observed using a metallographic microscope or a scanning electron microscope to measure the characteristic parameters of the deposition layer thickness and porosity at different locations. The characteristic parameters obtained at different locations are used to fit the spatial coordinates to obtain the curves of the characteristic parameters as a function of spatial location.

8. The spray gun trajectory optimization method according to claim 6, characterized in that, In the second step, the spray gun trajectory is optimized in simulation software by combining the specific bearing outer ring surface contour features and the spatial distribution curve of the deposition particle characteristic parameters. The geometric parameters of the bearing outer ring surface and the spatial distribution curve of the characteristic parameters obtained under different deposition conditions are used as input parameters. The coating thickness uniformity and the minimum coating porosity are used as the final optimization objectives. Numerical simulation is performed in computer software to coordinate the optimization of the spray gun trajectory, speed, acceleration and relative approximation ratio.

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