A nano-strengthening device and strengthening method

Abstract

This application discloses a nano-strengthening device and method, relating to the field of metal surface nano-strengthening technology. It not only achieves more uniform processing of ring-shaped parts but also enables the processing of thin-walled parts with non-circular cross-sections. The nano-strengthening device includes a symmetrical pressure control component, a constant pressure control component, and two sets of nano-strengthening tool assemblies. The symmetrical pressure control component includes a tool holder and a symmetrical pressure frame; the tool holder is slidably connected to the symmetrical pressure frame; the nano-strengthening tool assemblies are connected to the symmetrical pressure frame; a constant pressure control component and a pressure sensor are provided between one set of nano-strengthening tool assemblies and the symmetrical pressure frame; the constant pressure control component provides a constant pressure to the nano-strengthening tool assemblies; the pressure sensor detects the pressure between the nano-strengthening tool assemblies and multi-shaped ring-shaped parts in real time. This application also provides a strengthening method based on the above-described nano-strengthening device.

Description

Technical Field

[0001] This application relates to the field of metal surface nano-strengthening technology, and in particular to a nano-strengthening device and strengthening method. Background Technology

[0002] Traditional methods for nano-machining metal ring parts typically employ single-sided rolling or constant displacement methods. The single-sided rolling method suffers from the drawback of generating significant rolling pressure on the metal ring surface, making it highly susceptible to deformation, especially when machining thin-walled rotating parts. While the constant displacement method addresses deformation, it requires a strictly circular workpiece environment for nano-machining of ring parts, making it unsuitable for elliptical, square, or polygonal rings. Furthermore, precise alignment during clamping is crucial. Even with these limitations, when machining large ring-shaped parts, the extremely low indentation of the nano-tool during nano-machining still leads to uneven nano-machining across different areas, sometimes resulting in areas being unmachined while others are over-machined. Summary of the Invention

[0003] The embodiments of this application provide a nano-strengthening device and a strengthening method, which not only makes the processing of metal ring parts more uniform, but also can process thin-walled parts with non-circular cross-sections.

[0004] To achieve the above objectives, in one aspect, embodiments of this application provide a nano-reinforcement device, including a symmetrical pressure control component, a constant pressure control component, and two sets of nano-reinforced tool assemblies; the symmetrical pressure control component includes a tool holder and a symmetrical pressure frame; the symmetrical pressure frame is a U-shaped bracket connecting two free ends by a crossbeam; the upper end of the tool holder is connected to the tool holder of a CNC machine tool, and the lower end is slidably connected to the crossbeam; the two sets of nano-reinforced tool assemblies are respectively connected to the inner surfaces of their corresponding free ends; a constant pressure control component and a pressure sensor are provided between one set of nano-reinforced tool assemblies and the free end; the nano-reinforced tool assembly contacts and rolls with a multi-shaped annular part; the nano-reinforced tool assembly can cause localized plastic deformation of the surface of the multi-shaped annular part to generate dislocation nano-refined grains; the constant pressure control component can provide constant pressure to the nano-reinforced tool assembly; the pressure sensor can detect the pressure between the nano-reinforced tool assembly and the multi-shaped annular part in real time.

[0005] Furthermore, the symmetrical pressure control assembly also includes a slide rail; the slide rail is arranged along the extension direction of the crossbeam; the lower end of the tool holder is provided with a groove that matches the slide rail.

[0006] Furthermore, a constant pressure control component is also provided between another of the nano-reinforced tool components and the free end.

[0007] Furthermore, the constant pressure control assembly includes an air pump, a booster pump, a pressure regulating valve, a constant pressure air tank, and a piston cylinder connected in sequence; the fixed end of the piston cylinder is connected to the symmetrical pressure frame via a pressure sensor, and the telescopic end is connected to the tool holder via a connecting plate; the air pump can provide a base air pressure; the booster pump can increase the air pressure; the pressure regulating valve can stabilize the output air pressure of the booster pump; and the constant pressure air tank is used to buffer the air pressure changes caused by the piston's extension and retraction.

[0008] Furthermore, the constant pressure control assembly includes a hydraulic pump, a pressure regulating valve, a constant pressure hydraulic accumulator, and a piston hydraulic cylinder connected in sequence; the fixed end of the piston hydraulic cylinder is connected to a symmetrical pressure frame via a pressure sensor, and the telescopic end is connected to the tool holder via a connecting plate; the hydraulic pump can provide basic stable hydraulic pressure; the pressure regulating valve can stabilize the output hydraulic pressure of the hydraulic pump; the constant pressure hydraulic accumulator is used to buffer the hydraulic pressure changes caused by piston telescoping.

[0009] Furthermore, the nano-reinforced tool assembly includes a tool holder and a nano-reinforced tool connected to the tool holder; the tool holder is a U-shaped holder; the nano-reinforced tool is a wheel-type structure with a central hole, and a reinforcing head is provided in the middle of the wheel rim of the nano-reinforced tool, the reinforcing head being a protrusion that surrounds the wheel rim circumferentially; the nano-reinforced tool is connected to the U-shaped holder through a connecting shaft assembly; the nano-reinforced tool and the connecting shaft assembly are rotatably connected by a bearing.

[0010] Furthermore, the nano-reinforced cutting tool is provided with two bearing mounting holes, and a bearing is installed in the bearing mounting holes; the outer ring of the bearing is connected to the nano-reinforced cutting tool, and the inner ring is connected to the connecting shaft assembly.

[0011] Furthermore, both ends of the connecting shaft assembly are connected to the tool holder by screws; the connecting shaft assembly is provided with an external thread section, and a nut is connected to the external thread section, which can axially limit the two bearings.

[0012] Furthermore, the cross-section of the reinforcing head is semi-circular; the diameter of the semi-circle is d≤6mm; and the maximum diameter of the rim of the nano-reinforced tool is D≤20mm.

[0013] On the other hand, embodiments of this application also provide a strengthening method based on the above-mentioned nano-strengthening device, including the following steps: S1, mounting a multi-shaped ring-shaped part on a CNC machine tool rotary chuck, so that the rotary chuck supports the multi-shaped ring-shaped part from the inside, and mounting a tool holder on a tool holder; adjusting the position of the nano-strengthening tool to ensure that the strengthening head is aligned with the initial machining position of the ring-shaped metal part; S2, adjusting the constant pressure control component to press the strengthening head into the multi-shaped ring-shaped part, and ensuring that the pressing amount of the strengthening head meets the requirements through the detection value of the pressure sensor; S3, starting the CNC machine tool, the rotary chuck drives the multi-shaped ring-shaped part to rotate at the workpiece speed V2, and the nano-strengthening tool moves upward at the tool speed V1 to perform one or more rolling passes on the multi-shaped ring-shaped part until the nano-strengthening of the surface of the ring-shaped part is completed, and a deep gradient nano-layer is formed before stopping.

[0014] This application has the following advantages over the prior art:

[0015] 1. The nano-strengthening device in this application embodiment provides a slide rail between the tool holder and the symmetrical pressure frame, and a constant pressure control component between the symmetrical pressure frame and the nano-strengthening tool assembly. During the extension of the piston cylinder in the constant pressure control component, the portion below the tool holder is unrestricted in the horizontal direction and can slide arbitrarily according to the shape of the annular metal part. Therefore, deformation can be avoided when machining thin-walled parts. Simultaneously, by adjusting the piston cylinder pressure, high pressure is generated on both sides of the thin-walled part.

[0016] 2. The nano-strengthening device in this application embodiment provides a slide rail between the tool holder and the symmetrical pressure frame, so that the part below the tool holder can slide arbitrarily in the horizontal direction. This reduces the centering requirements of the workpiece. In addition, this application embodiment can also be applied to thin-walled parts with non-circular cross-sections such as elliptical or polygonal shapes with rounded corners.

[0017] 3. The nano-strengthening device in this application sets a constant pressure control component between the symmetrical pressure frame and the nano-strengthening tool assembly, so that the piston cylinder forms a certain amount of indentation on the annular metal part; at the same time, by setting a pressure sensor between the symmetrical pressure frame and the constant pressure control component to detect the pressure value in real time, the rolling pressure between the nano-strengthening tool component and the annular metal part is judged and controlled, thereby controlling the amount of indentation of the annular metal part, and thus accurately controlling the grain change scale and strengthening effect of its surface nano-strengthening.

[0018] 4. Compared with conventional devices using asymmetric, non-constant pressure systems, the nano-strengthening device of this application produces workpieces with better hardness uniformity.

[0019] 5. In the nano-strengthening device of this application embodiment, the nano-strengthening tool is axially limited by the bearing through the nut, which is beneficial to the nano-strengthening tool in terms of both structural stability and high precision under high-speed rotation. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a three-dimensional structural diagram of an embodiment of this application;

[0022] Figure 2 This is a bottom view of an embodiment of this application;

[0023] Figure 3 for Figure 2 AA section view;

[0024] Figure 4 This is a schematic diagram of the structure of the nano-reinforced cutting tool assembly in the embodiments of this application;

[0025] Figure 5 This is a schematic diagram of the structure of the nano-reinforced cutting tool in the embodiments of this application;

[0026] Figure 6 This is a comparison of the stress-strain curves of stainless steel 3mm diameter round bars and 6mm diameter round bars after nano-rolling in the embodiments of this application, and coarse-grained material CG of the same size.

[0027] Figure 7 The above are CG fatigue SN curves of stainless steel 3mm diameter round bars and 6mm diameter round bars after nano-rolling and the same size coarse-grained material.

[0028] Figure 8 This is a graph showing the relationship between the tensile strength and fatigue ratio of the workpiece in the embodiments of this application;

[0029] Figure 9 The tensile engineering stress-strain curves of the workpiece made of Ti in the embodiments of this application are shown.

[0030] Figure 10 The microhardness and corresponding microhardness microstructure of the cross section of the workpiece made of Ti after nano-sizing in the embodiments of this application are shown.

[0031] Figure 11This is a thermal stability diagram of the structure of the workpiece made of Ni in the embodiments of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not 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 application.

[0034] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly, for example, they can refer to fixed connections, detachable connections, or integral connections; those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0035] 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" can explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0036] Reference Figures 1 to 5 The embodiments of this application provide a nano-strengthening device, including a symmetrical pressure control component 1, a constant pressure control component 2, a pressure sensor 3, and two sets of nano-strengthening tool components 4.

[0037] The symmetrical pressure control assembly 1 includes a tool holder 11, a symmetrical pressure frame 12, and a slide rail 13. The symmetrical pressure frame 12 is a U-shaped bracket with two free ends connected by a crossbeam. The opening of the U-shaped bracket faces downward, and the slide rail 13 is disposed on the upper surface of the crossbeam along its extension direction. The upper end of the tool holder 11 is connected to the tool holder of a CNC machining center, and the lower end is connected to a slider 14. A groove adapted to the slide rail 13 is formed on the lower surface of the slider 14, thereby allowing the slide rail 13 to slide left and right within the groove.

[0038] Reference Figure 1 Two sets of nano-reinforced tool assemblies 4 are respectively connected to the inner surface of the free end corresponding to the symmetrical pressure control assembly 1. A constant pressure control assembly 2 and a pressure sensor 3 are provided between the right nano-reinforced tool assembly 4 and the free end. Thus, the CNC machining center can drive the embodiment of this application to move vertically upward at a tool speed V1, where V1 = 0.2 mm / min. The two sets of nano-reinforced tool assemblies 4 respectively contact and roll with the inner and outer walls of the multi-shaped ring part 5, so that local plastic deformation of the surface of the multi-shaped ring part 5 generates dislocation nano-refined grains, forming a reinforced layer with residual compressive stress.

[0039] The constant pressure control component 2 is used to control the rolling pressure between the nano-reinforced tool and the multi-shaped ring part 5, thereby controlling the amount of pressure applied to the multi-shaped ring part 5. The pressure sensor 3 can detect the pressure between the nano-reinforced tool assembly 4 and the multi-shaped ring part 5 in real time. The multi-shaped ring part 5 is supported and fixed from the inside by a rotary chuck, which is driven by the rotating magnetic pole of the CNC machining center to rotate at a workpiece speed V2, where V2 = 40000 mm / min. It should be noted that, to further improve the uniformity of machining, the constant pressure control component 2 can also be installed between the nano-reinforced tool assembly 4 on the left side and the free end.

[0040] It should be noted that the multi-shaped ring component 5 refers to a ring component with a circular cross-section as well as a non-circular structure with an elliptical cross-section or a polygon with rounded corners.

[0041] The nano-reinforced tool assembly 4 includes a tool holder 41 and a nano-reinforced tool 42 connected to the tool holder 41. The tool holder 41 is a U-shaped holder with two free ends. The nano-reinforced tool 42 is connected to the tool holder 41 via a connecting shaft assembly 45, and the two are rotatably connected by a bearing 43. The inner end of the nano-reinforced tool 42 contacts and rolls against the poly-shaped annular part 5, causing localized plastic deformation of the surface of the poly-shaped annular part 5 to generate dislocation nano-refined grains, forming a reinforced layer with residual compressive stress.

[0042] The nano-reinforced cutting tool 42 is a wheel-type structure with a central hole. A reinforcing head 44 is located in the center of its rim, and the reinforcing head 44 is a protrusion that surrounds the rim circumferentially and protrudes through a rounded chamfer. The cross-section of the reinforcing head 44 is semi-circular, with a diameter d = 6 mm. The maximum diameter of the rim of the nano-reinforced cutting tool 42 is D = 20 mm. Depending on the characteristics and shape of the area being machined, the nano-reinforced cutting tool 42 can be replaced with a hard-reinforced cutting head for localized fine machining, further increasing the applicability and practicality of this device while saving costs.

[0043] Two bearing mounting holes are provided on both ends of the central hole, and bearings 43 are installed in the bearing mounting holes. The outer ring of the bearing 43 is interference-fitted with the inner wall of the bearing mounting hole, and the inner ring is connected to the connecting shaft assembly 45.

[0044] For ease of installation, the connecting shaft assembly 45 includes a pin and a shouldered bushing fitted onto the middle section of the pin. The pin has an external thread section, on which a nut 46 is connected. The nut 46 provides axial restraint for the two bearings 43. The two ends of the pin are connected to the two free ends of the tool holder 41 by screws 47.

[0045] The constant pressure control component 2 includes an air pump (not shown), a booster pump (not shown), a pressure regulating valve (not shown), a constant pressure air tank (not shown), and a piston cylinder connected in sequence. The fixed end of the piston cylinder is connected to the symmetrical pressure frame 12 via a pressure sensor 3, and the telescopic end is equipped with a connecting plate, on which the tool holder 41 is mounted. The air pump provides the base air pressure, the booster pump increases the air pressure, the pressure regulating valve stabilizes the output air pressure of the booster pump, and the constant pressure air tank buffers the air pressure changes caused by the displacement of the piston cylinder.

[0046] In addition to using a constant air pressure control cylinder to control the pressure, a constant input hydraulic pressure can also be used to complete this machining process. Specifically, the constant pressure control component 2 includes a hydraulic pump (not shown in the figure), a pressure regulating valve (not shown in the figure), a constant pressure hydraulic accumulator (not shown in the figure), and a piston hydraulic cylinder (not shown in the figure) connected in sequence. The fixed end of the piston hydraulic cylinder is connected to the symmetrical pressure frame via a pressure sensor, and the telescopic end is connected to the tool holder via a connecting plate; the hydraulic pump can provide basic stable hydraulic pressure; the pressure regulating valve can stabilize the output hydraulic pressure of the hydraulic pump; the constant pressure hydraulic accumulator is used to buffer the hydraulic pressure changes caused by piston extension and retraction.

[0047] The multi-shaped ring part 5 can be made of aluminum alloy, copper alloy, stainless steel, GCr15, bearing 43 steel, or mold steel, etc. The nano-reinforced cutting tool 42 can be replaced with a fixed hardened cutting tool tip with a rolling structure.

[0048] The following description uses the processing of different multi-shaped ring parts 5 as an example to illustrate the effects.

[0049] Reference Figure 6 The multi-shaped ring part 5 is a metal ring part made of 316 stainless steel. The number of passes of the rolling track is 10, D=20mm, d=6mm.

[0050] Figure 6 The figure shows the stress-strain curves of 316 stainless steel material with a diameter of 3mm and 6mm after nano-rolling and coarse-grained material CG in the embodiments of this application. As shown in the figure, the material has a better yield limit. It can be seen from the stress-strain curve that the yield strength of the material has increased from 250MPa before nano-rolling to about 750MPa after nano-rolling.

[0051] Figure 7 The figure shows the fatigue SN curves of 316 stainless steel materials with 3mm and 6mm diameter nano-rolling and coarse-grained materials after the former, respectively, in the embodiments of this application. As shown in the figure, at 300MPa, the fatigue cycle count of the coarse-grained material is only 10. 3 After nano-sizing, the fatigue cycle count is increased to >10. 7 .

[0052] Figure 8 The graph shows the relationship between tensile strength and fatigue ratio. As shown in the figure, the nanomaterial properties of 316 stainless steel are significantly improved.

[0053] Reference Figure 9 The multi-shaped ring part 5 is a metal ring part made of pure Ti. The number of passes of the rolling track is 5, D=10mm, d=6mm.

[0054] Figure 9 The figures show the tensile stress-strain curves of a Ti-based metal ring. Curve A corresponds to a 2mm thick coarse-grained CG titanium tube. Curve B corresponds to a 2mm thick nano-sized GNG titanium tube. Curve C corresponds to a 1.5mm thick nano-sized GNG titanium tube. After nano-sizing, the yield strength of the titanium alloy increased from approximately 460MPa to approximately 650MPa.

[0055] Figure 10 The figure shows the microhardness and corresponding microstructure of the cross-section of a titanium (Ti) metal ring after nanostructuring. As shown, the hardness of the gradient nanolayers of the titanium alloy changes from 440 at the outermost layer to 150 at the core, while the original hardness of the substrate is 150. This demonstrates that nanostructuring significantly improves the hardness of Ti.

[0056] Table 1 shows the surface hardness distribution of Ti-based metal ring parts after nanostructuring. A1-A7 represent hardness values ​​obtained using the present invention, while B8-B14 represent hardness values ​​of nanostructural parts processed using a conventional asymmetric, non-constant pressure system. It is clearly evident that the uniformity of hardness values ​​in part A is significantly better than that in part B.

[0057] The table below shows the hardness values ​​of samples taken at multiple points every 100 mm on the surface of the Ti ring:

[0058] Invention Number A1 A2 A3 A4 A5 A6 A7 Hardness (Hv) 447 435 442 441 443 445 445 Comparative numbering B8 B9 B10 B11 B12 B13 B14 Hardness (Hv) 435 315 158 385 404 440 180

[0059] In summary, after using the nano-strengthening device of the present invention for nano-strengthening treatment of metal surfaces, the surface quality is better, the roughness can be lower than 0.02, and the nano-layer depth can be deeper, reaching 1000-2000um.

[0060] Reference Figure 11The multi-shaped ring part 5 is a metal ring part made of Ni. The number of passes of the rolling track is 1. The D = 5mm and d = 3mm.

[0061] Reference Figure 11 The figures illustrate the thermal stability of the nanoscale grain structure on the workpiece surface. Specifically, (A) is a grain size versus temperature curve after annealing for 1 hour. (B) is a TEM image of the nickel nanostructured sample. (C) is a TEM image of the nickel nanostructured sample after annealing at 500°C for 1 hour. As shown in the figures, the stress intensity is significantly improved after nano-strengthening treatment of the metal surface using the nano-strengthening device of this application. This set of figures demonstrates that the nanostructure has excellent thermal stability.

[0062] The above embodiments demonstrate that the nano-strengthening device of this application, employing constant air pressure coordination, exhibits better fault tolerance, can deepen the metal nanolayer, and improve the precision of surface nano-sizing. Simultaneously, the processing does not generate dust or chips, making it environmentally friendly. Furthermore, due to improvements in the rolling cutter, processing efficiency is significantly enhanced, indicating broad market application prospects.

[0063] Reference Figure 1 The embodiments of this application also provide a strengthening method based on the above-described nano-strengthening device, comprising the following steps:

[0064] Step S1: Install the annular metal part on the rotary chuck of the CNC machining center, so that the rotary chuck supports the multi-shaped annular part 5 from the inside; install the tool holder 11 on the tool holder, and adjust the position of the nano-reinforced tool 42 to ensure that the reinforcing head 44 is aligned with the initial machining position of the annular metal part.

[0065] Step S2: Adjust the constant pressure control component 2 so that the piston cylinder forms a certain amount of pressure on the annular metal part. Throughout the process, the rolling pressure between the nano-reinforced tool 42 and the annular metal part is judged and controlled based on the value displayed by the pressure sensor 3 while adjusting the pressure regulator, thereby controlling the amount of pressure pressed into the annular metal part.

[0066] Step S3: Activate the rotating magnetic pole of the CNC machining center, causing the rotating chuck, i.e., the ring-shaped metal part held in it, to rotate at a speed of V2; the tool holder 11 drives the other parts of this embodiment to move vertically upward at a speed of V1, starting the first rolling process on the ring-shaped metal part from bottom to top, and then stopping the rolling. It should be noted that the number of rolling passes is 1 to 10. If the rolling passes are only rolled once, the machining is complete; if they are rolled multiple times, proceed to step 4.

[0067] Step S4: After the first rolling is completed, the tool holder moves the whole thing back, so that the strengthening head 44 of the nano-strengthening tool 42 is realigned with the initial processing position of the annular metal part, and the second rolling begins. The preset indentation depth of the next pass is greater than the preset indentation depth of the previous pass. The above operation is repeated. While the annular metal part rotates in the circumferential direction, the nano-strengthening tool 42 adjusts the feed rate and moves vertically upward in the axial direction until the nano-strengthening of the annular metal part surface is completed.

[0068] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A nano-strengthening device, characterized in that, It includes a symmetrical pressure control component, a constant pressure control component, and two sets of nano-reinforced tool components; the symmetrical pressure control component includes a tool holder, a symmetrical pressure frame, and a slide rail; the symmetrical pressure frame is a U-shaped bracket with two free ends connected by a crossbeam; the opening of the U-shaped bracket faces downward, and the slide rail is set on the upper surface of the crossbeam along the extension direction of the crossbeam; the upper end of the tool holder is connected to the tool holder of the CNC machining center, and the lower end is connected to the slider, and a groove adapted to the slide rail is opened on the lower surface of the slider; Two sets of nano-reinforced tool assemblies are respectively connected to the inner surfaces of their corresponding free ends; a constant pressure control component and a pressure sensor are provided between one set of nano-reinforced tool assemblies and the free end; the nano-reinforced tool assemblies are rolled against the inner and outer walls of the multi-shaped ring-shaped part; the nano-reinforced tool assemblies can cause localized plastic deformation on the surface of the multi-shaped ring-shaped part to generate dislocation nano-refined grains; the constant pressure control component can provide constant pressure to the nano-reinforced tool assemblies; the pressure sensor can detect the pressure between the nano-reinforced tool assemblies and the multi-shaped ring-shaped part in real time; The nano-reinforced tool assembly includes a tool holder and a nano-reinforced tool connected to the tool holder; the tool holder is a U-shaped holder.

2. The nano-strengthening device according to claim 1, characterized in that, Another nano-reinforced tool assembly is also provided with a constant pressure control component between itself and the free end.

3. The nano-strengthening device according to claim 2, characterized in that, The constant pressure control assembly includes an air pump, a booster pump, an air pressure regulating valve, a constant pressure air tank, and a piston cylinder connected in sequence; the fixed end of the piston cylinder is connected to a symmetrical pressure frame via a pressure sensor, and the telescopic end is connected to... even The connecting plate is connected to the tool holder; the air pump can provide basic air pressure; the booster pump can increase the air pressure; The pressure regulating valve can stabilize the output pressure of the booster pump; the constant pressure tank is used to buffer the pressure changes caused by the piston extension and retraction.

4. The nano-strengthening device according to claim 2, characterized in that, The constant pressure control assembly includes a hydraulic pump, a pressure regulating valve, a constant pressure hydraulic accumulator, and a piston hydraulic cylinder connected in sequence; the fixed end of the piston hydraulic cylinder is connected to a symmetrical pressure frame via a pressure sensor, and the telescopic end is connected to... even The connecting plate is connected to the tool holder; the hydraulic pump can provide basic stable hydraulic pressure; the pressure regulating valve can stabilize the output hydraulic pressure of the hydraulic pump; the constant pressure hydraulic accumulator is used to buffer the hydraulic pressure changes caused by piston extension and retraction.

5. The nano-strengthening device according to claim 2 or 3, characterized in that, The nano-reinforced cutting tool is a wheel-type structure with a central hole. A reinforcing head is provided in the middle of the wheel rim of the nano-reinforced cutting tool. The reinforcing head is a protrusion that surrounds the wheel rim in the circumferential direction. The nano-reinforced cutting tool is connected to the U-shaped bracket through a connecting shaft assembly. The nano-reinforced cutting tool and the connecting shaft assembly are rotatably connected by a bearing.

6. The nano-strengthening device according to claim 5, characterized in that, The nano-reinforced cutting tool has two bearing mounting holes, and a bearing is installed in the bearing mounting holes; the outer ring of the bearing is connected to the nano-reinforced cutting tool, and the inner ring is connected to the connecting shaft assembly.

7. The nano-strengthening device according to claim 6, characterized in that, The two ends of the connecting shaft assembly are connected to the tool holder by screws; the connecting shaft assembly is provided with an external thread section, and a nut is connected to the external thread section, which can axially limit the two bearings.

8. The nano-strengthening device according to claim 7, characterized in that, The cross-section of the strengthening head is semi-circular; the diameter of the semi-circle is d≤6mm; the maximum diameter of the rim of the nano-strengthened tool is D≤20mm.

9. A strengthening method based on the nano-strengthening device according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Mount the multi-shaped ring-shaped part on the rotary chuck of the CNC machine tool, so that the rotary chuck supports the multi-shaped ring-shaped part from the inside, and mount the tool holder on the tool holder; adjust the position of the nano-reinforced tool to ensure that the reinforcing head is aligned with the initial machining position of the ring-shaped metal part; S2. Adjust the constant pressure control component to press the reinforcing head into the multi-shaped annular part, and ensure that the pressing amount of the reinforcing head meets the requirements by using the detection value of the pressure sensor; S3. Start the CNC machine tool, rotate the chuck to drive the multi-shaped ring part to rotate at the workpiece speed V2, and move the nano-reinforced tool upward at the tool speed V1 to perform one or more rolling passes on the multi-shaped ring part until the surface of the ring part is nano-reinforced and a deep gradient nano layer is formed, then stop.

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