Nanometer strengthening device and method

Abstract

The invention discloses a nanometer strengthening device and method, and relates to the technical field of metal surface nanometer strengthening. The thin and long shaft part is not prone to bending when being subjected to nanometer strengthening machining, the depth of a metal nanometer layer can be increased, and the precision and smoothness of surface nanocrystallization can be improved. The device comprises a first nanometer strengthening mechanism and a second nanometer strengthening mechanism, the first nanometer strengthening mechanism comprises a first annular cutter holder and a plurality of first nanometer strengthening cutter assemblies. A first constant pressure assembly and a first pressure sensor are arranged between each first nanometer strengthening cutter assembly and the annular cutter holder. The second nanometer strengthening mechanism comprises a second annular cutter holder and a plurality of second nanometer strengthening cutter assemblies. And a second constant pressure assembly and a second pressure sensor are arranged between each second nano reinforced cutter assembly and the annular cutter holder. The invention further provides a strengthening method based on the nanometer strengthening device.

Description

Technical Field

[0001] This application relates to the technical field of metal surface nano-strengthening, and particularly to a nano-strengthening device and method. Background Art

[0002] When performing surface nanocrystallization processing on traditional rod-shaped parts, the single-side rolling method or the constant displacement method is generally used. The disadvantage of the single-side rolling method is that due to the large rolling pressure generated on the surface of the rod-shaped part, it is extremely easy to deform, especially when processing slender rod-shaped parts, the deformation is particularly obvious. Although the constant displacement method can solve the problem of workpiece deformation, when using the constant displacement method for surface nanocrystallization processing of rod-shaped parts, rod-shaped parts with very good symmetry must be used, and strict centering must be carried out during clamping, and the dimensional accuracy requirements for the original sample are very high. Even so, when processing long thin wires and thin rods, because the penetration amount of the nanocrystallization tool is very low during the nanocrystallization process, there will still be problems such as uneven nanocrystallization in each area, and even problems such as some areas cannot be processed, while some areas are processed too deeply. In addition, the existing methods for processing slender shafts are all single-side opposed, which will cause problems such as processing bending.

[0003] The Chinese patent "A Three-Ball Tool for Treating the Surface Layer of Metal Materials to Improve Material Properties" (Publication No.: CN203048994 U) discloses a three-ball tool for treating the surface layer of shaft-like metal materials on a lathe to improve material properties. It sets a fixed seat on a fixed rod, and three dial indicator force boosters mounting holes distributed at an angle of 120° are arranged on the side of the fixed seat. A fixed seat center hole is arranged at the center of the fixed seat. The dial indicator force boosters mounting holes communicate with the fixed seat center hole respectively. Three dial indicator force boosters distributed at an angle of 120° are respectively installed in the three dial indicator force boosters mounting holes distributed at an angle of 120°. A cemented carbide ball is arranged between the dial indicator force booster and the fixed seat center hole, and the cemented carbide ball protrudes from the fixed seat center hole. The disadvantages of this structure are inconvenient use, low machining accuracy and difficult to ensure the size of nanocrystallization processing. Summary of the Invention

[0004] The embodiments of this application provide a nano-strengthening device and method, which are not only not easy to bend when performing nano-strengthening processing on slender shaft-like parts, but also can deepen the depth of the metal nano-layer, and can also improve the accuracy and surface finish of surface nanocrystallization.

[0005] To achieve the above object, on the one hand, an embodiment of the present application provides a nano-strengthening device, which includes a first nano-strengthening mechanism and a second nano-strengthening mechanism arranged in sequence along the axial direction; the first nano-strengthening mechanism includes a first annular tool holder and a plurality of first nano-strengthening tool assemblies; the plurality of first nano-strengthening tool assemblies are circumferentially distributed in the first annular tool holder, and a first constant pressure assembly and a first pressure sensor are provided between each first nano-strengthening tool assembly and the annular tool holder; the second nano-strengthening mechanism includes a second annular tool holder and a plurality of second nano-strengthening tool assemblies; the plurality of second nano-strengthening tool assemblies are circumferentially distributed in the second annular tool holder, and a second constant pressure assembly and a second pressure sensor are provided between each second nano-strengthening tool assembly and the annular tool holder; the second nano-strengthening tool assemblies and the first nano-strengthening tool assemblies are both in contact with and roll press on the slender shaft-like parts.

[0006] Further, the first annular tool holder includes an annular body and a tool shank; the tool shank is connected to the outer circumferential surface of the annular body, and the tool shank is connected to the tool post of the CNC lathe; the structure of the second annular tool holder is the same as that of the first annular tool holder, and the annular body of the second annular tool holder is connected to the annular body of the first annular tool holder.

[0007] Further, the first nano-strengthening tool includes a nano-strengthening tool base and a nano-strengthening ball; a groove is provided on the upper surface of the nano-strengthening tool base, the nano-strengthening ball sits in the groove and protrudes from the groove, and an avoidance notch is provided at the edge of the groove.

[0008] Further, the second nano-strengthening tool assembly includes a tool support and a second nano-strengthening tool; the tool support is a U-shaped support; the second nano-strengthening tool is a wheel-like structure with a central hole, and a strengthening head is provided in the middle of the wheel rim of the second nano-strengthening tool, and the strengthening head is a protrusion surrounding the wheel rim in the circumferential direction; the second nano-strengthening tool is connected to the U-shaped support through a connecting shaft assembly; the second nano-strengthening tool is rotatably connected to the connecting shaft assembly through a bearing.

[0009] Further, two bearing mounting holes are provided in the second nano-strengthening tool, and bearings are provided in the bearing mounting holes; the outer ring of the bearing is connected to the second nano-strengthening tool, and the inner ring is connected to the connecting shaft assembly.

[0010] Further, both ends of the connecting shaft assembly are connected to the tool support by screws; an external thread section is provided on the connecting shaft assembly, and a nut is connected to the external thread section, and the nut can axially limit the two bearings.

[0011] Furthermore, the strengthening head protrudes directly from the rim or protrudes through an arc chamfer; the cross-section of the strengthening head is a semi-circle; the diameter d of the semi-circle is ≤ 6 mm; the maximum diameter D of the rim of the nano-strengthening tool is ≤ 20 mm.

[0012] Furthermore, the first constant pressure assembly includes a gas pump, a booster pump, a pneumatic pressure regulating valve, a constant pressure gas tank, and a piston cylinder connected in sequence; the fixed end of the piston cylinder is connected to the annular body through a pressure sensor, and the telescopic end is connected to the tool holder through a connecting plate; the gas pump can provide a basic air pressure; the booster pump can increase the air pressure; the pneumatic pressure regulating valve can stabilize the output air pressure of the booster pump; the constant pressure gas tank is used to buffer the air pressure change caused by the piston telescoping; the structure of the second constant pressure assembly is the same as that of the first constant pressure assembly.

[0013] Furthermore, the first constant pressure assembly includes a hydraulic pump, a pressure regulating valve, a constant pressure hydraulic energy storage device, and a piston hydraulic cylinder connected in sequence; the fixed end of the piston hydraulic cylinder is connected to the annular body through a pressure sensor, and the telescopic end is connected to the tool holder through a connecting plate; the hydraulic pump can provide a basic stable hydraulic pressure; the pressure regulating valve can stabilize the output hydraulic pressure of the hydraulic pump; the constant pressure hydraulic energy storage device is used to buffer the hydraulic change caused by the piston telescoping; the structure of the second constant pressure assembly is the same as that of the first constant pressure assembly.

[0014] On the other hand, an embodiment of the present application also provides a strengthening method based on the above nano-strengthening device, including the following steps: S1. Fix the slender shaft-like part on the chuck of the CNC lathe, install the nano-strengthening device of the embodiment of the present application on the tool rest, ensure that the slender shaft-like part passes through the centers of the first annular tool holder and the second annular tool holder, and the first annular tool holder is in the initial machining position of the slender shaft-like part; S2. Adjust the first constant pressure assembly and the second constant pressure assembly so that each second nano-strengthening tool and the second nano-strengthening tool are pressed into the slender shaft-like part, and the pressure is measured in real time through the first pressure sensor and the second pressure sensor; S3. Start the CNC lathe, the chuck drives the slender shaft-like part to rotate, the tool rest drives the second nano-strengthening tool and the second nano-strengthening tool to move axially, and perform one or more rolling operations on the slender shaft-like part until the nano-strengthening of the surface of the slender shaft-like part is completed and then stop.

[0015] The present application has the following beneficial effects compared with the prior art:

[0016] 1. In the nano - strengthening device of the embodiment of the present application, by arranging a first annular tool holder and a second annular tool holder arranged axially, and respectively arranging a plurality of nano - strengthening tools evenly distributed circumferentially in the two annular tool holders, and also by arranging a constant - pressure component between the tool and the tool holder, multiple evenly distributed pressures are generated on the outer cylindrical surface of the slender shaft - like part by adjusting the pressure of the constant - pressure component, thereby avoiding the bending of the slender shaft - like part caused by uneven force during the processing. At the same time, by utilizing the principle of the coordinated action of constant air pressure, the nano - strengthening device has elasticity, reduces the symmetry requirement for the slender shaft - like part, and further improves the accuracy of surface nanocrystallization by arranging a pressure sensor between the annular tool holder and the constant - pressure component to detect the pressure value in real - time.

[0017] 2. The nano - strengthening device of the embodiment of the present application is provided with two rows of nano - strengthening tools. The first nano - strengthening tool located at the front side is preferentially rolled to pre - form a nano - layer first. While the second nano - strengthening tool located at the rear side performs secondary nano - rolling, it increases the depth of the nano - layer and improves the surface finish.

[0018] 3. Compared with traditional tools, the depth of the nano - layer processed by the nano - strengthening device of the embodiment of the present application can be increased by 2 - 4 times, the influence of the deformed layer can reach more than 2000μm, and the nano - strengthening effect, efficiency, and surface finish are all significantly improved. The surface finish can reach below 0.02 in laboratory tests.

[0019] 4. Compared with the device using a conventional asymmetric and non - constant - pressure system, the hardness uniformity of the workpiece processed by the nano - strengthening device of the embodiment of the present application is better.

[0020] 5. In the nano - strengthening device of the embodiment of the present application, the nano - strengthening tool axially limits the bearing through a nut, which is beneficial for the nano - strengthening tool to balance structural stability and high precision under high - speed rotation. In addition, since the smaller the cross - sectional diameter of the strengthening head, the greater the pressure on the surface of the workpiece to be processed and the better the nano - strengthening effect, the nano - strengthening device of the embodiment of the present application forms a relatively deep gradient nano - layer on the metal surface by making the maximum value D of the rim of the nano - strengthening tool ≤ 20mm and the cross - sectional diameter d of the strengthening head ≤ 6mm.

[0021] 6. The nano - strengthening tool in the nano - strengthening device of the embodiment of the present application is provided with an avoidance notch at the edge of the groove of the nano - strengthening tool base, so that it can also process samples with corners. At the same time, due to the smaller friction area, the rolling friction is smaller and the lubricity is higher. Description of the Drawings

[0022] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0023] Figure 1 Schematic diagram of the three-dimensional structure of the embodiment of the present application;

[0024] Figure 2 Cross-sectional view of the embodiment of the present application;

[0025] Figure 3 Schematic diagram of the structure of the second nano-strengthening mechanism in the embodiment of the present application;

[0026] Figure 4 Schematic diagram of the three-dimensional structure of the first nano-strengthening tool in the embodiment of the present application;

[0027] Figure 5 Cross-sectional view of the first nano-strengthening tool in the embodiment of the present application;

[0028] Figure 6 Schematic diagram of the structure of the second nano-strengthening tool in the embodiment of the present application;

[0029] Figure 7 Schematic diagram of the maximum value of the rim of the second nano-strengthening tool and the cross-sectional diameter of the strengthening head in the embodiment of the present application;

[0030] Figure 8 Comparison diagram of the stress-strain curves of 3mm diameter round bars and 6mm diameter round bar samples of stainless steel material after nano-rolling with those of the coarse-grained material CG of the same size in the embodiment of the present application;

[0031] Figure 9 Fatigue S-N curve diagram of 3mm diameter round bars and 6mm diameter round bar samples of stainless steel material after nano-rolling with those of the coarse-grained material CG of the same size in the embodiment of the present application;

[0032] Figure 10 Relationship diagram between the tensile strength and fatigue ratio of the workpiece in the embodiment of the application;

[0033] Figure 11 Tensile engineering stress-strain curve of the workpiece with the material of Ti in the embodiment of the application;

[0034] Figure 12 Microhardness of the cross-section of the workpiece with the material of Ti after nano-treatment and the corresponding microhardness microstructure in the embodiment of the application;

[0035] Figure 13Thermal stability diagram of the structure of the workpiece made of Ni in the application embodiment. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0037] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and 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 should not be construed as a limitation to the present application.

[0038] In the description of the present application, it should be noted that unless otherwise clearly defined and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; for those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0039] 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 quantity of the indicated technical features. Thus, the features defined with "first" and "second" can explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0040] Referring to Figures 1 to 7 , the embodiments of the present application provide a nano-strengthening device, including a first nano-strengthening mechanism and a second nano-strengthening mechanism arranged in sequence along the axial direction.

[0041] The first nano-strengthening mechanism includes a first annular tool holder 1 and three second nano-strengthening tool assemblies 2. The three second nano-strengthening tool assemblies 2 are evenly distributed circumferentially in the first annular tool holder 1. A first constant pressure assembly 3 and a first pressure sensor 4 are provided between each second nano-strengthening tool assembly 2 and the annular tool holder. The first constant pressure assembly 3 can provide a constant pressure for the second nano-strengthening tool assembly 2. The first pressure sensor 4 can detect the pressure between the second nano-strengthening tool assembly 2 and the slender shaft-like part 5 in real time.

[0042] The first annular tool holder 1 includes an annular body 11 and a tool shank 12. The inner ring surface of the annular body 11 is a regular hexagon structure. Three second nano-strengthened tool assemblies 2 are circumferentially distributed in the annular body 11. The tool shank 12 is arranged on the outer circular surface of the annular body 11 and is connected to the tool rest of the CNC lathe. The tool shank 12 is a prior art and will not be elaborated here.

[0043] Refer to Figure 4 and Figure 5 , the first nano-strengthened tool assembly 2 includes a nano-strengthened tool base 21 and a nano-strengthened ball 22. The diameter of the nano-strengthened ball 22 is generally less than or equal to 8 mm. A groove 23 is provided on the upper surface of the nano-strengthened tool base 21. The nano-strengthened ball 22 sits in the groove 23 and protrudes from the groove 23. An avoidance notch 24 is provided at the edge of the groove 23. The avoidance notch 24 enables it to process samples with corners. At the same time, due to the smaller friction area, the rolling friction is smaller and the lubricity is higher. In addition, the first nano-strengthened tool assembly 2 can be replaced with other tools according to the characteristics and morphology of the processed area for processing, further increasing the application range and practicability of the device and saving costs.

[0044] The first constant pressure assembly 3 includes an air pump (not shown in the figure), a booster pump (not shown in the figure), a pneumatic pressure regulating valve (not shown in the figure), a constant pressure air tank (not shown in the figure) and a piston cylinder 31 that are connected in sequence. The fixed end of the piston cylinder 31 is connected to the annular body 11 through a first pressure sensor 4. A connecting plate (not shown in the figure) is provided at the telescopic end, and the nano-strengthened tool base 21 is installed on the connecting plate. The air pump can provide the basic air pressure, the booster pump can increase the air pressure, the pneumatic 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 change caused by the displacement of the piston cylinder 31. The second nano-strengthening mechanism includes a second annular tool holder 6 and three second nano-strengthened tool assemblies 7. The structure of the second annular tool holder 6 is the same as that of the first annular tool holder, and the annular body of the second annular tool holder 6 is connected to the annular body of the first annular tool holder 1. Three second nano-strengthened tool assemblies 7 are circumferentially distributed in the second annular tool holder 6, and a second constant pressure assembly 8 and a second pressure sensor 9 are provided between each second nano-strengthened tool assembly 7 and the annular tool holder. The second nano-strengthened tool assembly 7 contacts and rolls on the slender shaft-like part 5.

[0045] The second nano-strengthened tool assembly 7 includes a tool support 71 and a second nano-strengthened tool 72. The tool support 71 is a U-shaped support with two free ends. The second nano-strengthened tool 72 is connected to the U-shaped support through a connecting shaft assembly and is rotatably connected to each other through a bearing 73. The second nano-strengthened tool 72 contacts and rolls on the slender shaft-like part 5 to cause local plastic deformation on the surface of the slender shaft-like part 5 to generate dislocation and nano-refined grains.

[0046] The second nano-reinforced tool 72 is a wheel-shaped structure with a central hole, and a reinforcement head 74 is provided in the middle of the wheel rim. The reinforcement head 74 is a protrusion that surrounds the wheel rim in the circumferential direction. The cross-section of the reinforcement head 74 is a semi-circle, and the diameter d of the semi-circle is 4 mm. The maximum diameter D of the wheel rim of the second nano-reinforced tool 72 is 20 mm. According to the characteristics and shape of the processed area, the second nano-reinforced tool 72 can be replaced with a hard reinforcement tool head for local fine processing, further increasing the application range and practicability of the device and saving costs.

[0047] Two bearing mounting holes are provided on both end faces of the central hole, and bearings 73 are provided in the bearing mounting holes. The outer ring of the bearing 73 is in interference fit with the inner wall of the bearing mounting hole, and the inner ring is connected to the connecting shaft assembly 25.

[0048] For the convenience of installation, the connecting shaft assembly includes a pin shaft 76 and a shoulder bushing 77 sleeved on the middle section of the pin shaft 76. An external thread section is provided on the pin shaft 76, and a nut 77 is connected to the external thread section. The nut 76 can axially limit the two bearings 73. Both ends of the pin shaft are connected to the two free ends of the tool support 71 by screws 78.

[0049] The structure of the second constant pressure assembly 8 is the same as that of the first constant pressure assembly 3, and will not be described in detail here.

[0050] In addition, in addition to using the method of controlling the pressure by a constant air pressure to control the cylinder, a constant input hydraulic pressure can also be used, and this processing scheme can be completed by using the hydraulic control method. Specifically, both the first constant pressure assembly 3 and the second constant pressure assembly 8 include a hydraulic pump (not shown in the figure), a pressure regulating valve (not shown in the figure), a constant pressure hydraulic energy storage device (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 annular body through a pressure sensor, and the telescopic end is connected to the tool support through a connecting plate; the hydraulic pump can provide a basic stable hydraulic pressure; the pressure regulating valve can stabilize the output hydraulic pressure of the hydraulic pump; the constant pressure hydraulic energy storage device is used to buffer the hydraulic pressure change caused by the piston telescoping. The material of the slender shaft-like part 5 can be aluminum alloy, copper alloy, stainless steel, GCr15, bearing 73 steel, or die steel, etc.

[0051] The following takes the processing of slender shaft-like parts 5 of different materials in this application as an example to describe its effects.

[0052] Refer to Figure 8 , the material of the slender shaft-like part 5 is 316 stainless steel.

[0053] Figure 8The stress-strain curve diagram of the 316 stainless steel material with a diameter of 3mm and 6mm after nano-rolling and the coarse-grained material CG in the embodiment of the present application is 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 is increased from 250MPa before nano-treatment to about 750MPa after nano-treatment.

[0054] Figure 9 The fatigue S-N curve diagram of the 316 stainless steel material with a diameter of 3mm and 6mm after nano-rolling and the coarse-grained material CG in the embodiment of the present application is shown in the figure. Under 300MPa, the fatigue cycle times of the coarse-grained material are only 10 3 , and the fatigue cycle times are increased to >10 after nano-treatment 7 .

[0055] Figure 10 The relationship diagram between the tensile strength and the fatigue ratio is shown in the figure. The nano-material properties of the 316 stainless steel material are significantly improved.

[0056] Refer to Figure 11 , and the material of the slender shaft part 5 is pure Ti.

[0057] Figure 11 The tensile engineering stress-strain curve of the metal ring part with the material of Ti is shown. The material corresponding to curve A is the CG coarse-grained titanium tube with a wall thickness of 2mm. The material corresponding to curve B is the nano-structured GNG titanium tube with a wall thickness of 2mm. The material corresponding to curve C is the nano-structured GNG titanium tube with a wall thickness of 1.5mm. After the titanium alloy is nano-structured, the yield strength is increased from the original about 460MPa to about 650MPa.

[0058] Figure 12 The microhardness of the cross-section of the metal ring part with the material of Ti after nano-treatment and the corresponding microhardness microstructure are shown. As shown in the figure, the hardness of the gradient nano-layer of the titanium alloy changes from the surface hardness of 440 to the core hardness of 150, and the original hardness of the substrate is 150. It can be seen that the nano-treatment has greatly improved the hardness of Ti.

[0059] Table 1 shows the surface hardness distribution of the metal slender rod part with the material of Ti after nano-treatment. Among them, the numbers A1-A7 are the hardness values using the present invention, and B8-B14 are the hardness values of the nano-treated parts processed by using the conventional asymmetric and non-constant pressure system. It can be clearly seen that the hardness value uniformity of part A is significantly better than that of part B.

[0060] The following table shows the hardness values of multiple points sampled every 100mm on the surface layer of the Ti rod:

[0061] Serial number of the present invention A1 A2 A3 A4 A5 A6 A7 Hardness (Hv) 447 435 442 441 443 445 445 Serial number of the comparative example B8 B9 B10 B11 B12 B13 B14 Hardness (Hv) 435 315 158 385 404 440 180

[0062] In summary, after the metal surface is nano-strengthened by using the nano-strengthening device of the present invention, the surface quality is better, the roughness can be lower than 0.02, and the depth of the nano-layer can be deeper, reaching 1000 - 2000 um.

[0063] Referring to Figure 13 , the material of the slender shaft part 5 is Ni.

[0064] Referring to Figure 13 , which shows the thermal stability of the nano-scale grain structure on the surface of the workpiece. Specifically, (A) is the graph of grain size versus temperature after annealing for 1 hour. (B) is the TEM sample after nickel nano-crystallization. (C) is the TEM image after nickel nano-crystallization and then annealing at 500 °C for 1 hour. As shown in the figure, after the metal surface is nano-strengthened by using the nano-strengthening device of the present application, the stress intensity is greatly improved. This set of figures shows that the nano-structure has very good thermal stability.

[0065] The above embodiments show that the nano-strengthening device of the present application has better fault tolerance by the coordinated action of constant air pressure, can deepen the depth of the metal nano-layer, and improve the accuracy of surface nano-crystallization.

[0066] Referring to Figure 1 Figure 2 , the embodiment of the present application also provides a strengthening method based on the nano-strengthening device for the slender shaft part 5, including the following steps:

[0067] S1. Fix the slender shaft part 5 on the chuck of the CNC lathe, install the nano-strengthening device of the embodiment of the present application on the tool post, ensure that the slender shaft part 5 passes through the centers of the first annular tool holder 1 and the second annular tool holder 6, and the first annular tool holder 1 is at the initial machining position of the slender shaft part 5;

[0068] S2. Adjust the first constant pressure assembly 3 and the second constant pressure assembly 8 so that each second nano-strengthening tool 72 and the second nano-strengthening tool are pressed into the slender shaft part 5, and the pressure is measured in real time through the first pressure sensor 4 and the second pressure sensor 9;

[0069] S3. Start the CNC lathe, the chuck drives the slender shaft part 5 to rotate, the tool post drives the second nano-strengthening tool 72 and the second nano-strengthening tool to move axially, and perform one or more passes of rolling on the slender shaft part 5 until the nano-strengthening of the surface of the slender shaft part 5 is completed and then stop.

[0070] Specifically, before the second and subsequent passes of rolling, the pistons in the two groups of constant air pressure assemblies need to be retracted first, the two groups of nano-strengthening tools are withdrawn, and then the two groups of tools are moved to the machining position of the slender shaft part 5 and then continue the machining.

[0071] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A nano-enhancement device, characterized in that: It includes a first nano-enhancing mechanism and a second nano-enhancing mechanism which are arranged in sequence along the axial direction; the first nano-enhancing mechanism includes a first annular tool holder and a plurality of first nano-enhanced tool assemblies; the plurality of the first nano-enhanced tool assemblies are evenly distributed in the first annular tool holder along the circumferential direction, and a first constant pressure assembly and a first pressure sensor are provided between each first nano-enhanced tool assembly and the annular tool holder; the second nano-enhancing mechanism includes a second annular tool holder and a plurality of second nano-enhanced tool assemblies; the plurality of the second nano-enhanced tool assemblies are evenly distributed in the second annular tool holder along the circumferential direction, and a second constant pressure assembly and a second pressure sensor are provided between each second nano-enhanced tool assembly and the annular tool holder; the second nano-enhanced tool assembly and the first nano-enhanced tool assembly are both in contact with and rolled on a slender shaft-like part.

2. The nano-enhancement device according to claim 1, characterized in that: The first annular tool holder includes an annular body and a tool handle; the tool handle is connected to the outer circumferential surface of the annular body, and the tool handle is connected to the tool holder of the CNC lathe; the structure of the second annular tool holder is the same as that of the first annular tool holder, and the annular body of the second annular tool holder is connected to the annular body of the first annular tool holder.

3. The nano-enhancement device according to claim 2, characterized in that: The first nano-enhanced tool comprises a nano-enhanced tool base and a nano-enhanced ball; a groove is provided on the upper surface of the nano-enhanced tool base, the nano-enhanced ball sits in the groove and protrudes from the groove, and an avoidance notch is provided at the edge of the groove.

4. The nano-enhancement device according to claim 3, characterized in that: The second nano-enhanced tool assembly includes a tool holder and a second nano-enhanced tool; the tool holder is a U-shaped holder; the second nano-enhanced tool is a wheel-type structure with a center hole, and a strengthening head is provided in the middle of the wheel rim of the second nano-enhanced tool, and the strengthening head is a protrusion circumferentially surrounding the wheel rim; the second nano-enhanced tool is connected to the U-shaped holder through a connecting shaft assembly; the second nano-enhanced tool and the connecting shaft assembly are rotatably connected through a bearing.

5. The nano-enhancement device according to claim 4, characterized in that: Two bearing mounting holes are arranged in the second nano-enhanced tool, and bearings are arranged in the bearing mounting holes; the outer ring of the bearing is connected to the second nano-enhanced tool, and the inner ring is connected to the connecting shaft assembly.

6. The nano-enhancement device according to claim 5, characterized in that: The two ends of the connecting shaft assembly are connected to the tool support by screws; the connecting shaft assembly is provided with an external thread section, and a nut is connected to the external thread section, and the nut can axially limit the two bearings.

7. The nano-enhancement device according to claim 6, characterized in that: The strengthening head protrudes directly from the wheel rim or protrudes through arc chamfering; the cross section of the strengthening head is a semicircle; the diameter d of the semicircle is ≤6mm; the maximum diameter D of the wheel rim of the nano-strengthening tool is ≤20mm.

8. The nano-enhancement device according to claim 7, characterized in that: The first constant pressure component includes an air pump, a booster pump, an air pressure regulating valve, a constant pressure air tank and a piston cylinder which are connected in sequence; the fixed end of the piston cylinder is connected to the annular body via a pressure sensor, and the telescopic end is connected to the tool holder via a connecting plate; the air pump can provide basic air pressure; the booster pump can increase the air pressure; the air pressure regulating valve can stabilize the output air pressure of the booster pump; the constant pressure air tank is used to buffer the air pressure changes caused by the extension and retraction of the piston; the structure of the second constant pressure component is the same as the first constant pressure component.

9. The nano-enhancement device according to claim 7, characterized in that: The first constant pressure component 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 the annular body through a pressure sensor, and the telescopic end is connected to the tool holder through 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 changes caused by the extension and retraction of the piston; the structure of the second constant pressure component is the same as the first constant pressure component.

10. A method for strengthening a nano-strengthening device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Fix the slender shaft-like part on the chuck of the CNC lathe, install the nano-enhancement device of the embodiment of the present application on the tool holder, ensure that the slender shaft-like part passes through the center of the first annular tool holder and the second annular tool holder, and the first annular tool holder is in the initial processing position of the slender shaft-like part; S2, adjusting the first constant pressure component and the second constant pressure component so that each of the second nano-enhanced cutting tools and the second nano-enhanced cutting tools are pressed into the slender shaft-like component, and measuring the pressure in real time through the first pressure sensor and the second pressure sensor; S3, start the CNC lathe, the chuck drives the slender shaft-like part to rotate, the tool holder drives the second nano-enhanced tool and the second nano-enhanced tool to move axially, and perform one or more rolling passes on the slender shaft-like part until the nano-enhancing of the surface of the slender shaft-like part is completed and then stop.

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