Preparation method of wear-resistant coating on outer surface of shaft part with special-shaped structure

Abstract

The invention discloses a preparation method of a wear-resistant coating on the outer surface of a shaft special-shaped structure part. The preparation method mainly comprises the following steps: S1, protecting a non-spraying area of the part by adopting a protective clamp I and a protective sleeve; s2, carrying out wear-resistant coating spraying on the part spraying area by adopting high velocity oxy-fuel spraying; s3, a second protection clamp and a protection sleeve are adopted for protecting the sprayed area of the boss area of the part; and S4, a wear-resistant coating is sprayed for the second time. According to the method, the coating thickness is controlled in a partitioned mode, specifically, the coating thickness of a special-shaped spraying area on the side face of the boss is controlled within a small range (0.05-0.10 mm), and the coating thickness of a regular cylindrical section is controlled within a normal range (0.25-0.35 mm); according to the method, the large-thickness-difference wear-resistant coating of the shaft type special-shaped spraying structure is prepared through the process of carrying out partitioned secondary spraying through the clamp and the methods of spraying path control and the like, coating cracking caused by stress concentration of a coating in a special-shaped spraying area is avoided, the wear resistance of parts is improved, and the service life of the parts is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of preparation of wear-resistant coatings for aero-engine shaft parts, and more specifically, relates to a method for preparing wear-resistant coatings on the outer surfaces of shaft-type special-shaped structural parts. Background Art

[0002] The transmission shaft of an aviation blower and its counterpart sealing ring form a sealing structure, in which the transmission shaft is a high-speed rotating part with a speed of about 30,000 r / min, and the sealing ring is a stationary part. The blower shaft and the sealing ring perform relative rotational motion. In a high-speed working environment, in order to prevent the transmission shaft from failing due to wear after long-term service, a tungsten carbide-cobalt wear-resistant coating needs to be sprayed on the contact area between the transmission shaft and the sealing ring.

[0003] The transmission shaft spraying area is a special-shaped structure, such as the attached Figure 1 As shown in the figure, the structure is composed of a cylindrical section + a boss section. The spraying area of ​​the cylindrical section is a regular outer circular surface; the spraying structure of the boss section is more complicated, as shown in the figure. Figure 2 As shown in the figure, the side of the boss is composed of 2 segments of arc surface + 2 segments of plane alternately connected to form a non-annular special-shaped spray surface, and there are 4 edges at the transition between the arc surface and the plane. Due to the large difference in curvature between the arc surface and the plane, the deformation of the coating on the arc surface and the plane is different, resulting in a large internal stress inside the coating. In addition, the tungsten carbide coating is a ceramic coating, which is hard and brittle, which eventually causes stress concentration and cracking of the coating at the transition of the edges on the side of the boss, thereby causing the transmission shaft part to fail.

[0004] Invention patent CN113969388B discloses a method for preparing a wear-resistant coating on the inner surface of a part with a large aspect ratio, which includes a masking treatment and a step of spraying a cobalt-chromium-nickel-tungsten powder on the inner surface of the part with a large aspect ratio by supersonic flame spraying to obtain a coating. The spraying structure is a regular annular spraying surface, and the solution cannot be adapted to the spraying of the outer surface of an irregular axial part with a large difference in curvature between the arc surface and the plane. Summary of the invention

[0005] Aiming at the problem that irregular annular special-shaped spraying structures are prone to stress concentration and thus cause coating cracking, the present invention proposes a process scheme of coating thickness zoning control and phased zoning spraying to solve the coating cracking problem caused by the spraying structure.

[0006] A method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part comprises the following steps:

[0007] S1: Use protective fixture 1 and protective cover to protect the non-spraying area of ​​the parts;

[0008] S2: Use supersonic flame spraying to spray the wear-resistant coating on the spraying area of ​​the parts;

[0009] S3: Use protective fixture 2 and protective cover to protect the sprayed area of ​​the boss area of ​​the part;

[0010] S4: Secondary spraying of wear-resistant coating;

[0011] When spraying S2, the spray gun is perpendicular to the axis and moves in a straight line from top to bottom along the axis;

[0012] When the S4 is sprayed, the spray gun is tilted downward, with an angle of 20° to 40° with the horizontal direction, and moves in an arc along the axis in the boss section and in a straight line along the axis in the cylindrical section.

[0013] Furthermore, the part spraying area includes a cylindrical section and a boss section, the cylindrical section is a regular outer cylindrical surface, the boss section includes a boss side surface, a boss upper end surface and a boss lower end surface, the boss side surface includes a non-annular spraying surface in which arc surfaces and planes are alternately connected, the coating thickness of the boss side surface is 0.05 to 0.1 mm, and the coating thickness of the cylindrical section and the boss upper end surface is 0.25 mm to 0.35 mm.

[0014] Furthermore, the protective clamp 1 adopts a half-structure design and is fixedly connected by bolts. The upper opening contacts the lower end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A locking screw is also provided on the protective clamp 1.

[0015] Furthermore, the second protective clamp adopts a half-structure design and is fixedly connected by bolts. The depth of the upper opening is flush with the lower end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A locking screw is also provided on the second protective clamp.

[0016] Furthermore, the protective sleeve is a cylindrical structure, the opening of the lower end is conical, and matches with the conical surface of the upper part of the part, and a locking screw is also provided on the protective sleeve.

[0017] Furthermore, the wear-resistant coating is a tungsten carbide-cobalt coating.

[0018] Furthermore, before the processing in step S1, the steps of cleaning and degreasing the surface of the parts and roughening by sand blasting are also included.

[0019] Furthermore, the sandblasting roughening step is: firstly, a high temperature resistant protective tape is used to protect the non-spraying area of ​​the part, and then sandblasting roughening is performed.

[0020] Furthermore, the step S4 also includes cleaning and grinding operations on the surface of the parts.

[0021] Furthermore, the cleaning operation is to remove burrs on the edge of the part coating; the grinding operation is to grind the coating on the cylindrical section and the upper end surface coating on the boss to remove the machining allowance.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention controls the coating thickness by zoning: the coating thickness of the special-shaped spraying area on the side of the boss is controlled within a smaller range (0.05-0.10mm), and the coating thickness of the regular cylindrical section is controlled within a normal range (0.25-0.35mm); the process of zoned secondary spraying by a fixture and the spraying path control method are used to realize the preparation of wear-resistant coatings with large thickness differences for special-shaped spraying structures of shafts, avoid coating cracking caused by stress concentration in the special-shaped spraying area, improve the wear resistance of parts, and extend the service life of parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of a transmission shaft part;

[0025] Figure 2 It is a schematic cross-sectional view of a boss section of a transmission shaft component structure;

[0026] Figure 3 It is a structural schematic diagram of the protective clamp 1;

[0027] Figure 4 It is a structural schematic diagram of the second protective clamp;

[0028] Figure 5 It is a schematic diagram of the protective cover structure;

[0029] Figure 6 This is a schematic diagram of the assembly of the fixture 1, the protective cover and the parts in step S1;

[0030] Figure 7 It is a schematic diagram of the combination of the second fixture, the protective cover and the parts in step S3;

[0031] Figure 8 This is a schematic diagram of the movement trajectory of the spray gun during S2 spraying;

[0032] Fig. 9 This is a schematic diagram of the movement trajectory of the spray gun during S4 spraying;

[0033] Fig.10 The present invention is a flow chart of a method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part;

[0034] Among them: 1. Threaded hole one; 2. Threaded hole two; 3. Threaded hole three. DETAILED DESCRIPTION

[0035] In order to clearly illustrate the technical features of this solution, the present invention is described in detail below through specific implementation methods and in combination with the accompanying drawings. In the following description, many specific details are described to facilitate a full understanding of the present application, but the present application can also be implemented in other ways different from those described herein, so the protection scope of the present application is not limited by the specific embodiments disclosed below. In addition, in the description of the present application, it should be understood that the orientation or position relationship indicated by the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of this application, "multiple" means two or more, unless otherwise clearly specified and specifically defined. In this application, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection, an electrical connection, or a communication; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances. In this application, unless otherwise clearly specified and defined, the first feature "on" or "under" the second feature can be the first and second features directly contacting, or the first and second features indirectly contacting through an intermediate medium. In the description of this specification, the description of the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representation of the above terms does 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 any one or more embodiments or examples.

[0036] Example 1

[0037] The following is combined with Figure 1 ~Attached Fig.10 , this embodiment provides a method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part.

[0038] As attached Figure 2 and attached Figure 3 The figure shows a schematic diagram of the structure of a boss section of a transmission shaft part structure, wherein the spraying area of ​​the part includes a cylindrical section and a boss section, the cylindrical section is a regular outer cylindrical surface, the boss section includes a boss side surface and a boss upper end surface, and the boss side surface includes a non-annular spraying surface in which arc surfaces and planes are alternately connected; since the magnitude of the internal stress of the coating is related to the coating thickness, the greater the coating thickness, the greater the internal stress of the coating; and the special-shaped spraying structure on the side of the boss of the part is more likely to cause stress concentration of the coating at the edge of the side of the boss (the transition point between the arc and the plane), resulting in cracking of the coating.

[0039] In order to avoid cracking of the coating caused by stress concentration at the edges of the boss side, while improving the wear resistance of the parts and meeting the service requirements of the parts, the present invention proposes a new spraying idea: that is, the coating thickness of the entire spraying area of ​​the part is controlled in a zoned manner: the coating thickness of the regular cylindrical section is controlled within a normal range (0.25-0.35mm) to meet the requirements of subsequent grinding of the coating and the surface roughness of the coating; for the special-shaped spraying area on the side of the boss, the coating thickness is controlled within a smaller range (0.05-0.10mm) to reduce the internal stress of the coating, avoid stress concentration of the coating, and improve the compatibility of the coating with the spraying structure.

[0040] In order to achieve the above object, the present invention provides the following technical solutions:

[0041] A method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part comprises the following steps:

[0042] S1: Use protective fixture 1 and protective cover to protect the non-spraying area of ​​the parts;

[0043] The protective clamp 1 adopts a half-structure design and is fixedly connected by bolts. The upper opening contacts the lower end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A threaded hole 1 is also provided on the protective clamp 1 for fastening the part and the clamp into a whole.

[0044] The protective cover is a cylindrical structure with a closed upper end and an open lower end. The lower opening is conical, with an angle of 20° with the axis, and matches the conical surface of the upper part of the part. Two threaded holes 3 are opened at symmetrical positions on the outer wall of the protective cover, and the protective cover is fixed on the part by bolts extruding in opposite directions.

[0045] When the fixture is clamped, the left and right halves of the base are combined to shield the parts from spraying and the fixture and parts are fastened as a whole by bolts, as shown in the attached Figure 6 shown.

[0046] S2: Use supersonic flame spraying to spray the wear-resistant coating on the spraying area of ​​the parts;

[0047] During the S1 spraying, the part rotates along the axis, the spray gun is perpendicular to the axis and moves in a straight line from top to bottom along the axis, and the spray gun trajectory covers the cylindrical section + boss section spraying area. The spray gun trajectory is as shown in the attached figure. Figure 8 As shown, the film thickness is controlled at 0.05 mm. At this time, for the special-shaped spraying area on the side of the boss, the film thickness has met the design requirements, but the coating thickness of the cylindrical section has not yet reached the required size.

[0048] S3: Use protective fixture 2 and protective cover to protect the sprayed area of ​​the boss area of ​​the part;

[0049] The second protective clamp adopts a half-structure design and is fixed by bolts. The upper opening depth is flush with the lower end surface of the boss, and the opening shape is consistent with the boss contour. The second protective clamp is also provided with a threaded hole 2 for fastening the part and the clamp into a whole. After the spraying step S2 is completed, the coating thickness of the side of the boss has reached the required size, and the coating on the outer side of the boss needs to be protected, and the cylindrical section area continues to be sprayed. At this time, the first protective clamp is removed from the part, and the second protective clamp is clamped. The assembly diagram is as shown in the attached figure. Figure 7 shown.

[0050] S4: Secondary spraying of wear-resistant coating;

[0051] Adjust the spraying procedure and only spray the cylindrical section spraying area for the second time. Since the cylindrical section is a regular annular surface, the internal stress of the coating here is small, and the coating thickness can be controlled at 0.25mm. At the same time, in order to improve the spraying coverage and powder deposition efficiency of the boss end face, the spray gun should be tilted downward at an angle of 20° to the horizontal direction; in order to prevent the coating from accumulating at right angles and causing the coating thickness to be too large and cracking, the spray gun should deviate from the axis at the boss end face and move in an arc to the side, that is, the movement trajectory of the spray gun is a straight line and an arc. The spray gun trajectory is as shown in the attached Fig. 9 shown.

[0052] The main idea of ​​the process of secondary spraying of the parts is to design a special spraying protection fixture according to the part structure; to perform segmented protection and fast fixture change during the spraying process according to the characteristics of the graded and zoned spraying of the parts; the fixture combination includes a protective fixture 1, a protective fixture 2 and a protective sleeve. Due to the presence of a special-shaped boss structure and a spline structure on the surface of the transmission shaft, the parts cannot be clamped axially. The fixture combination adopts a half-structure design. Through the radial clamping method, the interference of the part structure on the fixture clamping can be avoided, and the fixture can be quickly clamped and disassembled. At the same time, the coating and the fixture are avoided to bridge and protect the integrity of the coating.

[0053] According to the tungsten carbide-cobalt coated parts prepared in this embodiment, the coating thickness meets the design requirements, and no coating cracking occurs on the special-shaped surface of the boss, and the service life after installation is greatly improved.

[0054] Example 2

[0055] The following is combined with Figure 1 ~Attached Fig.10 This embodiment provides a method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part. Different from Embodiment 1, this embodiment performs a post-processing operation on the sprayed parts. The specific steps are as follows:

[0056] S1: Use protective fixture 1 and protective cover to protect the non-spraying area of ​​the parts;

[0057] The protective clamp 1 adopts a half-structure design and is fixedly connected by bolts. The upper opening contacts the lower end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A threaded hole 1 is also provided on the protective clamp 1 for fastening the part and the clamp into a whole.

[0058] The protective cover is a cylindrical structure with a closed upper end and an open lower end. The lower opening is conical, with an angle of 20° with the axis, and matches the conical surface of the upper part of the part. Two threaded holes 3 are opened at symmetrical positions on the outer wall of the protective cover, and the protective cover is fixed on the part by bolts extruding in opposite directions.

[0059] When the fixture is clamped, the left and right halves of the base are combined to shield the parts from spraying and the fixture and parts are fastened as a whole by bolts, as shown in the attached Figure 6 shown.

[0060] S2: Use supersonic flame spraying to spray the wear-resistant coating on the spraying area of ​​the parts;

[0061] During the S1 spraying, the part rotates along the axis, the spray gun is perpendicular to the axis and moves in a straight line from top to bottom along the axis, and the spray gun trajectory covers the cylindrical section + boss section spraying area. The spray gun trajectory is as shown in the attached figure. Figure 8 As shown, the film thickness is controlled at 0.1 mm. At this time, for the special-shaped spraying area on the side of the boss, the film thickness has met the design requirements, but the coating thickness of the cylindrical section has not yet reached the required size.

[0062] S3: Use protective fixture 2 and protective cover to protect the sprayed area of ​​the boss area of ​​the part;

[0063] The second protective clamp adopts a half-structure design and is fixed by bolts. The upper opening depth is flush with the lower end surface of the boss, and the opening shape is consistent with the boss contour. The second protective clamp is also provided with a threaded hole 2 for fastening the part and the clamp into a whole. After the spraying step S2 is completed, the coating thickness of the side of the boss has reached the required size, and the coating on the outer side of the boss needs to be protected, and the cylindrical section area continues to be sprayed. At this time, the first protective clamp is removed from the part, and the second protective clamp is clamped. The assembly diagram is as shown in the attached figure. Figure 7 shown.

[0064] S4: Secondary spraying of wear-resistant coating;

[0065] Adjust the spraying procedure and only spray the cylindrical section spraying area for the second time. Since the cylindrical section is a regular annular surface, the internal stress of the coating here is small, and the coating thickness can be controlled at 0.35mm. At the same time, in order to improve the spraying coverage and powder deposition efficiency of the boss end face, the spray gun should be tilted downward at an angle of 20° to the horizontal direction; in order to prevent the coating from accumulating at right angles and causing the coating thickness to be too large and cracking, the spray gun should deviate from the axis at the end face of the boss and move in an arc to the side, that is, the movement trajectory of the spray gun is a straight line and an arc. The spray gun trajectory is as shown in the attached Fig. 9 shown.

[0066] The main idea of ​​the process of secondary spraying of the parts is to design a special spraying protection fixture according to the part structure; to perform segmented protection and fast fixture change during the spraying process according to the characteristics of the graded and zoned spraying of the parts; the fixture combination includes a protective fixture 1, a protective fixture 2 and a protective sleeve. Due to the presence of a special-shaped boss structure and a spline structure on the surface of the transmission shaft, the parts cannot be clamped axially. The fixture combination adopts a half-structure design. Through the radial clamping method, the interference of the part structure on the fixture clamping can be avoided, and the fixture can be quickly clamped and disassembled. At the same time, the coating and the fixture are avoided to bridge and protect the integrity of the coating.

[0067] Furthermore, the step S4 also includes cleaning and grinding operations on the surface of the parts.

[0068] Through post-processing operations, the coating burrs on the surface of the parts are cleaned and the excess is ground to reduce the surface roughness and make the assembly tighter.

[0069] According to the tungsten carbide-cobalt coated parts prepared in this embodiment, the coating thickness meets the design requirements, and no coating cracking occurs on the special-shaped surface of the boss, and the service life after installation is greatly improved.

[0070] Example 3

[0071] The following is combined with Figure 1 ~Attached Fig.10 This embodiment provides a method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part. Different from Embodiment 1, this embodiment performs a step of cleaning and degreasing the parts before spraying and a step of sandblasting and roughening. The specific steps are:

[0072] Before spraying, use a detergent to clean the oil stains on the surface of the parts, and then use high-temperature resistant protective tape to protect the non-spraying areas of the parts. After protection, sandblasting is performed to roughen the parts. This step can further improve the adhesion of the coating.

[0073] S1: Use protective fixture 1 and protective cover to protect the non-spraying area of ​​the parts;

[0074] The protective clamp 1 adopts a half-structure design and is fixedly connected by bolts. The upper opening contacts the lower end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A threaded hole 1 is also provided on the protective clamp 1 for fastening the part and the clamp into a whole.

[0075] The protective cover is a cylindrical structure with a closed upper end and an open lower end. The lower opening is conical, with an angle of 20° with the axis, and matches the conical surface of the upper part of the part. Two threaded holes 3 are opened at symmetrical positions on the outer wall of the protective cover, and the protective cover is fixed on the part by bolts extruding in opposite directions.

[0076] When the fixture is clamped, the left and right halves of the base are combined to shield the parts from spraying and the fixture and parts are fastened as a whole by bolts, as shown in the attached Figure 6 shown.

[0077] S2: Use supersonic flame spraying to spray the wear-resistant coating on the spraying area of ​​the parts;

[0078] During the S1 spraying, the part rotates along the axis, the spray gun is perpendicular to the axis and moves in a straight line from top to bottom along the axis, and the spray gun trajectory covers the cylindrical section + boss section spraying area. The spray gun trajectory is as shown in the attached figure. Figure 8 As shown, the film thickness is controlled at 0.8 mm. At this time, for the special-shaped spraying area on the side of the boss, the film thickness has met the design requirements, but the coating thickness of the cylindrical section has not yet reached the required size.

[0079] S3: Use protective fixture 2 and protective cover to protect the sprayed area of ​​the boss area of ​​the part;

[0080] The second protective clamp adopts a half-structure design and is fixed by bolts. The upper opening depth is flush with the lower end surface of the boss, and the opening shape is consistent with the boss contour. The second protective clamp is also provided with a threaded hole 2 for fastening the part and the clamp into a whole. After the spraying step S2 is completed, the coating thickness of the side of the boss has reached the required size, and the coating on the outer side of the boss needs to be protected, and the cylindrical section area continues to be sprayed. At this time, the first protective clamp is removed from the part, and the second protective clamp is clamped. The assembly diagram is as shown in the attached figure. Figure 7 shown.

[0081] S4: Secondary spraying of wear-resistant coating;

[0082] Adjust the spraying procedure and only spray the cylindrical section spraying area for the second time. Since the cylindrical section is a regular annular surface, the internal stress of the coating here is small, and the coating thickness can be controlled at 0.3mm. At the same time, in order to improve the spraying coverage and powder deposition efficiency of the boss end face, the spray gun should be tilted downward at an angle of 20° to the horizontal direction; in order to prevent the coating from accumulating at right angles and causing the coating thickness to be too large and cracking, the spray gun should deviate from the axis at the end of the boss and move in an arc to the side, that is, the movement trajectory of the spray gun is a straight line and an arc. The spray gun trajectory is as shown in the attached Fig. 9shown.

[0083] The main idea of ​​the process of secondary spraying of the parts is to design a special spraying protection fixture according to the part structure; to perform segmented protection and fast fixture change during the spraying process according to the characteristics of the graded and zoned spraying of the parts; the fixture combination includes a protective fixture 1, a protective fixture 2 and a protective sleeve. Due to the presence of a special-shaped boss structure and a spline structure on the surface of the transmission shaft, the parts cannot be clamped axially. The fixture combination adopts a half-structure design. Through the radial clamping method, the interference of the part structure on the fixture clamping can be avoided, and the fixture can be quickly clamped and disassembled. At the same time, the coating and the fixture are avoided to bridge and protect the integrity of the coating.

[0084] Furthermore, in order to prevent the coating from bridging and sticking between the fixture and the part, a layer of protective tape is wrapped around the contact surface between the part boss and the protective fixture 2 to increase the clamping gap between the part and the protective fixture 2. During spraying, a separation zone is formed between the part and the fixture coating to prevent the coating from falling off due to adhesion.

[0085] According to the tungsten carbide-cobalt coated parts prepared in this embodiment, the coating thickness meets the design requirements, and no coating cracking occurs on the special-shaped surface of the boss, and the service life after installation is greatly improved.

[0086] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part, characterized in that: The steps include: S1: Use protective fixture 1 and protective cover to protect the non-spraying area of ​​the parts; S2: Use supersonic flame spraying to spray the wear-resistant coating on the spraying area of ​​the parts; S3: Use protective fixture 2 and protective cover to protect the sprayed area of ​​the boss area of ​​the part; S4: Secondary spraying of wear-resistant coating; During the S2 spraying, the spray gun is perpendicular to the axis and moves in a straight line along the axis; When the S4 is sprayed, the spray gun is tilted downward, with an angle of 20° to 40° with the horizontal direction, and moves in an arc along the axis in the boss section and in a straight line along the axis in the cylindrical section.

2. The method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part according to claim 1, characterized in that: The part spraying area includes a cylindrical section and a boss section, the cylindrical section is a regular outer cylindrical surface, the boss section includes a boss side surface, a boss upper end surface and a boss lower end surface, the boss side surface includes a non-annular spraying surface alternately connected by arc surfaces and planes, the coating thickness of the boss side surface is 0.05 to 0.1 mm, and the coating thickness of the cylindrical section and the boss upper end surface is 0.25 mm to 0.35 mm.

3. The method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part according to claim 1, characterized in that: The protective clamp 1 adopts a half-structure design and is fixedly connected by bolts. The upper opening fits the lower end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A locking screw is also provided on the protective clamp 1.

4. The method for preparing a wear-resistant coating on the outer surface of a shaft-like special-shaped structural part according to claim 1, characterized in that: The second protective clamp adopts a half-structure design and is fixedly connected by bolts. The depth of the upper opening is flush with the upper end surface of the boss, and the shape of the opening is consistent with the contour of the boss. A locking screw is also provided on the second protective clamp.

5. The method for preparing a wear-resistant coating on the outer surface of a shaft-like special-shaped structural part according to claim 1, characterized in that: The protective sleeve is a cylindrical structure, and the opening at the lower end is conical, which matches the conical surface of the upper part of the part. A locking screw is also arranged on the protective sleeve.

6. The method for preparing a wear-resistant coating on the outer surface of a shaft-like special-shaped structural part according to claim 1, characterized in that: The wear-resistant coating is a tungsten carbide-cobalt coating.

7. The method for preparing a wear-resistant coating on the outer surface of a shaft-like special-shaped structural part according to claim 1, characterized in that: The S1 step also includes the steps of cleaning and degreasing the surface of the parts and the step of sand blasting and roughening the surface of the parts before the treatment.

8. The method for preparing a wear-resistant coating on the outer surface of a shaft-like special-shaped structural part according to claim 7, characterized in that: The sandblasting roughening step is: firstly, a high temperature resistant protective tape is used to protect the non-spraying area of ​​the part, and then sandblasting roughening is performed.

9. The method for preparing a wear-resistant coating on the outer surface of a shaft-like special-shaped structural part according to claim 1, characterized in that: The S4 step also includes cleaning and grinding operations on the surface of the parts.

10. The method for preparing a wear-resistant coating on the outer surface of a shaft-type special-shaped structural part according to claim 9, characterized in that: The cleaning operation is to remove burrs on the edge of the part coating; the grinding operation is to grind the coating on the cylindrical section and the upper end surface coating on the boss to remove the machining allowance.

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