Ultrasound vibration assisted precision cutting of polycrystalline metal surface treatment device and method

Abstract

The present application belongs to the technical field of ultra-precision machining, and particularly relates to a polycrystalline metal surface treatment device and method for ultrasonic vibration assisted precision cutting, comprising: a cutter for cutting the surface of a workpiece; a cutter feeding table having a first base and a Z-direction moving end connected with the cutter; an elliptical ultrasonic vibration system, the vibration end of which is connected with the cutter to form an elliptical motion track for the cutter tip; a workpiece moving carrier having a second base, an X-direction moving end and a rotating end, the rotating end being connected with the workpiece; and a spectral confocal sensor located on one side of the workpiece for acquiring three-dimensional topography data. The method comprises pre-treating the workpiece, fixing the workpiece on the rotating end and aligning the center of rotation to establish a coordinate system, setting the machining parameters according to the functional microstructure, real-time evaluating the machining quality through the spectral confocal sensor, and cleaning the surface of the workpiece after machining. The present application synchronously completes the micro-texture forming and the sub-surface gradient fine-grain layer construction under single clamping, and obtains a high-quality surface with both functionality and mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of ultra-precision machining technology, and particularly relates to a device and method for surface treatment of polycrystalline metals assisted by ultrasonic vibration for precision cutting. Background Technology

[0002] Polycrystalline copper, due to its excellent electrical and thermal conductivity and good ductility, is widely used in electronic packaging, microwave devices, and precision optical molds. These high-end applications place extremely high demands on the high-quality surface of polycrystalline copper. The surface must possess specific microtextures to control functions such as friction, wetting, or optical diffraction, while the subsurface must have high hardness and uniform microstructure to ensure long-term service performance. Research shows that constructing a gradient nanocrystalline structure in the subsurface layer of polycrystalline metals can effectively improve surface mechanical properties. The gradient layer can progressively transfer strain, suppress strain localization and crack initiation, and significantly improve fatigue and wear resistance.

[0003] Currently, although ultra-precision single-point diamond turning can achieve nanoscale surface roughness and can process microtextures with the help of slow-tool servo or fast-tool servo technology, polycrystalline copper is prone to anisotropic deformation due to the random distribution of grain orientation and size. During the cutting process, defects such as surface wrinkles, grain boundary steps and subsurface dislocation pile-up are easily generated, making it difficult to simultaneously achieve precise forming of functional microtextures and active control of subsurface grains.

[0004] Existing microstructure manufacturing methods (such as ion beam etching and femtosecond laser processing) and surface strengthening methods are usually independent of each other, with complex processes, high costs, and difficulty in simultaneously meeting the needs of surface functionalization and improving long-term service performance.

[0005] Therefore, there is an urgent need for a device and method for surface treatment of polycrystalline metals with ultrasonic vibration-assisted precision cutting. Summary of the Invention

[0006] The purpose of this invention is to provide an apparatus and method for surface treatment of polycrystalline metals using ultrasonic vibration-assisted precision cutting, in order to solve the above-mentioned problems.

[0007] To achieve the above objectives, the present invention provides the following solution: An ultrasonic vibration-assisted precision cutting device for polycrystalline metal surface treatment includes: Cutting tools are used to cut the surface of a workpiece. The tool feed table has a first base and a Z-axis moving end. The tool is connected to the Z-axis moving end. The moving direction of the Z-axis moving end is perpendicular to the surface of the workpiece. The Z-axis moving end causes the tip of the tool to act on the surface of the workpiece at a set feed speed and feed depth. An elliptical ultrasonic vibration system has a control end and a vibration end. The vibration end is connected to the cutting tool to make the cutting tip of the tool vibrate to form a cutting trajectory. The cutting trajectory is formed by the high-frequency vibration of the cutting tip of the tool in the cutting direction and the depth of cut direction to form an elliptical motion trajectory on the surface of the workpiece. The control end is used to control the vibration amplitude and vibration frequency of the cutting tip of the tool. A workpiece moving carrier has a second base, an X-axis moving end, and a rotating end. The rotating end is connected to the workpiece. The X-axis moving end is used to adjust the position of the workpiece, and the rotating end is used to make the workpiece rotate at a set speed. The moving direction of the X-axis moving end is perpendicular to the moving direction of the Z-axis moving end. A spectral confocal sensor is used to acquire three-dimensional topographic data of the workpiece surface, and the spectral confocal sensor is located on one side of the workpiece.

[0008] Optionally, a force gauge is also included to obtain the pressure value between the tool and the workpiece, the force gauge being disposed between the first base and the Z-axis moving end.

[0009] Optionally, the rotating end is fixed to the workpiece by a cylindrical vacuum suction cup.

[0010] Optionally, the elliptical ultrasonic vibration system enables the cutting tool tip to generate a peak amplitude of 0–4 μm in both the bending vibration direction and the longitudinal vibration direction.

[0011] Optionally, the rake angle of the cutting tool is 10° and the clearance angle is 0°.

[0012] A polycrystalline metal surface treatment method, using the aforementioned ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment apparatus, includes the following steps: The workpiece is pretreated to make its surface smooth, clean, and free of scratches and contamination; The workpiece is fixed on the rotating end, the tip of the cutting tool is aligned with the rotation center of the workpiece, and a machining coordinate system is established with the rotation center as the origin. The feed rate, feed depth, vibration amplitude, vibration frequency, and rotational speed are set according to the functional microstructure of the workpiece surface to be processed. The three-dimensional morphology data of the processed surface is acquired in real time by the spectral confocal sensor, and the processing quality is evaluated. Clean the surface of the workpiece after processing.

[0013] Optionally, in the pretreatment step of the workpiece, the surface of the workpiece is sanded with sandpaper, and then the surface of the workpiece is mechanically polished. Finally, the mechanically polished workpiece is ultrasonically cleaned.

[0014] Optionally, during the process of aligning the tip of the cutting tool with the rotation center of the workpiece, a small amount of trial cutting is performed on the surface of the workpiece to form fine cut marks; The location of the fine cuts was observed under a microscope, and the tool holder height was repeatedly adjusted to ensure that the tool tip trajectory accurately passed through the center of rotation of the workpiece.

[0015] Optionally, during the cleaning process after processing, the workpiece surface is ultrasonically cleaned to remove residual chips and cutting fluid, followed by drying and clean packaging.

[0016] Optionally, the vibration frequency is 39.7 kHz.

[0017] Compared with the prior art, the present invention has the following advantages and technical effects: This invention utilizes an elliptical ultrasonic vibration system to drive a cutting tool in a combined vibration along the cutting direction and depth of cut, forming an elliptical trajectory. This achieves high-frequency intermittent contact between the tool and the workpiece, precisely machining functional microstructures with predetermined morphologies onto the workpiece surface. Simultaneously, the high-frequency impact and periodic plastic loading of the tool on the workpiece surface induce high dislocation density and plastic strain accumulation in the subsurface layer, forming a gradient fine-grained layer with gradually increasing grain size from the surface inwards. This gradient fine-grained layer pins dislocation movement, improves microstructure uniformity, enhances the surface hardness and resistance to plastic deformation, and suppresses strain localization and crack initiation, thereby improving the workpiece's fatigue and wear resistance under friction, impact, and cyclic loading conditions. A force gauge allows for real-time monitoring of cutting pressure and optimization of machining parameters. A cylindrical vacuum chuck ensures workpiece clamping stability. A spectral confocal sensor enables in-situ detection, avoiding secondary clamping errors. This invention requires no post-processing steps, has high process integration, and exhibits good industrial economics and scalability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a process flow diagram of the present invention; Figure 3-6 Comparison of the machined surfaces obtained by ultrasonic vibration turning of polycrystalline copper ellipse and conventional diamond turning. Figure 7-8This is a comparison of the ultra-smooth surfaces obtained by off-site grain refinement assisted turning and in-situ grain refinement assisted turning of polycrystalline copper according to the present invention. Figure 9 This is a comparison of the surface hardness obtained after ultrasonic vibration turning of polycrystalline copper ellipse and conventional diamond turning according to the present invention. Figure 10-13 This is a comparison of the machined surfaces obtained after elliptical ultrasonic vibration turning of polycrystalline copper under different amplitudes according to the present invention; Among them, 1. cutting tool; 2. cutting tool feed table; 3. force gauge; 4. workpiece; 6. workpiece moving carrier; 7. elliptical ultrasonic vibration system. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] Reference Figures 1 to 13 This invention discloses an ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment device, comprising: Cutting tool 1 is used to cut the surface of workpiece 4; The tool feed table 2 has a first base and a Z-axis moving end. The tool 1 is connected to the Z-axis moving end. The moving direction of the Z-axis moving end is perpendicular to the surface of the workpiece 4. The Z-axis moving end causes the tip of the tool 1 to act on the surface of the workpiece 4 at a set feed speed and feed depth. The elliptical ultrasonic vibration system 7 has a control end and a vibration end. The vibration end is connected to the tool 1 so that the tip of the tool 1 vibrates to form a cutting trajectory. The cutting trajectory is formed by the high-frequency vibration of the tip of the tool 1 in the cutting direction and the depth of cut, which forms an elliptical motion trajectory on the surface of the workpiece 4. The control end is used to control the vibration amplitude and vibration frequency of the tip of the tool 1. The workpiece moving carrier 6 has a second base, an X-axis moving end and a rotating end. The rotating end is connected to the workpiece 4. The X-axis moving end is used to adjust the position of the workpiece 4, and the rotating end is used to make the workpiece 4 rotate at a set speed. The moving direction of the X-axis moving end is perpendicular to the moving direction of the Z-axis moving end. A spectral confocal sensor is used to acquire three-dimensional topographic data of the surface of workpiece 4. The spectral confocal sensor is located on one side of workpiece 4.

[0022] The device includes a cutting tool 1, a tool feed stage 2, an elliptical ultrasonic vibration system 7, a workpiece moving carrier 6, and a spectral confocal sensor. The tool feed stage 2 has a first base and a Z-axis moving end. The cutting tool 1 is connected to the Z-axis moving end, and the moving direction of the Z-axis moving end is perpendicular to the surface of the workpiece 4. A set feed speed and depth allow the cutting tip of the cutting tool 1 to act on the surface of the workpiece 4. The vibration end of the elliptical ultrasonic vibration system 7 is connected to the cutting tool 1, causing the cutting tip of the cutting tool 1 to combine high-frequency vibrations in the cutting direction and the depth of cut, forming an elliptical motion trajectory on the surface of the workpiece 4. A control end is used to control the vibration amplitude and frequency. The workpiece moving carrier 6 has a second base, an X-axis moving end, and a rotating end. The rotating end is connected to the workpiece 4. The X-axis moving end is used to adjust the position of the workpiece 4, and the rotating end is used to rotate the workpiece 4 at a set speed. The X-axis moving direction is perpendicular to the Z-axis moving direction. The spectral confocal sensor is located on one side of the workpiece 4 and is used to acquire three-dimensional topographic data of the surface of the workpiece 4. This device integrates elliptical ultrasonic vibration-assisted cutting and in-situ detection functions, providing a hardware foundation for the simultaneous realization of microtexture formation and subsurface gradient fine grain layer construction.

[0023] As an optional implementation, a force gauge 3 is also included to obtain the pressure value between the tool 1 and the workpiece 4. The force gauge 3 is disposed between the first base and the Z-axis moving end.

[0024] A force gauge 3 is installed between the first base of the tool feed stage 2 and the Z-axis moving end to obtain the pressure value between the tool 1 and the workpiece 4. By monitoring the pressure changes in real time during the cutting process, it is possible to determine whether the contact state between the tool 1 and the workpiece 4 is stable, providing data support for optimizing ultrasonic vibration parameters and feed parameters, and avoiding abnormal cutting forces that could lead to a decrease in surface quality or damage to the tool 1.

[0025] As an optional implementation, the rotating end is fixed to the workpiece 4 by a cylindrical vacuum chuck.

[0026] The rotating end of the workpiece moving carrier 6 is fixed to the workpiece 4 by a cylindrical vacuum chuck. This fixing method provides uniform adsorption force without damaging the surface of the workpiece 4, ensuring the stability of the workpiece 4 during high-speed rotation, reducing clamping deformation and end face runout, and improving the surface accuracy and micro-weave forming consistency of the machined surface.

[0027] As an optional implementation, the elliptical ultrasonic vibration system 7 enables the tip of the tool 1 to generate a peak amplitude of 0 to 4 μm in both the bending vibration direction and the longitudinal vibration direction.

[0028] The elliptical ultrasonic vibration system 7 enables the tool tip 1 to generate peak amplitudes of 0~4μm in both the bending and longitudinal vibration directions. By independently adjusting the amplitude in both directions, the shape of the elliptical trajectory of the tool tip can be changed, actively controlling the morphological features of the microstructure on the machined surface, such as discrete micro-pits, scaly or mesh-like textures, while simultaneously controlling the depth of subsurface plastic deformation and the thickness of the gradient fine grain layer.

[0029] As an optional implementation, the rake angle of the tool 1 is 10° and the clearance angle is 0°.

[0030] In elliptical ultrasonic vibration assisted cutting, a larger rake angle helps reduce cutting force and frictional heat, and suppresses plastic buildup on the machined surface; a clearance angle of 0° increases the contact area between the tool 1 and the workpiece 4, enhances the grain refinement effect of high-frequency impact on the surface material, and promotes the formation of a gradient fine grain layer.

[0031] And a polycrystalline metal surface treatment method, using the aforementioned ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment apparatus, includes the following steps: Pre-treat workpiece 4 to make its surface smooth, clean, and free of scratches and contamination; Fix workpiece 4 on the rotating end, align the tip of tool 1 with the rotation center of workpiece 4, and establish a machining coordinate system with the rotation center as the origin; The feed rate, feed depth, vibration amplitude, vibration frequency, and rotation speed are set according to the functional microstructure of the surface of the workpiece to be processed. The three-dimensional topography data of the machined surface is acquired in real time using a spectral confocal sensor to evaluate the machining quality. Clean the surface of the workpiece after processing.

[0032] This method enables simultaneous microwoven fabric formation and subsurface reinforcement under single clamping and single cutting conditions.

[0033] Specifically, it includes: Step 1: Pre-processing of workpiece 4.

[0034] Step 2: Clamping and precision tool setting of workpiece 4.

[0035] Step 3: Elliptical ultrasonic vibration-assisted turning modification machining.

[0036] Step 4: In-situ inspection of the machined surface.

[0037] Step 5: Disassembly and ultrasonic cleaning of workpiece 4.

[0038] The driving tool 1 performs high-frequency composite vibration in the cutting direction and the depth of cut, so that the tool tip forms an elliptical motion trajectory relative to the surface of the workpiece 4. By adjusting the vibration amplitude, vibration direction combination relationship and turning parameters, the action trajectory of the tool 1 on the polycrystalline copper surface is controlled, thereby machining a functional microstructure with predetermined morphology, size and distribution characteristics on the surface of the workpiece 4. At the same time, by utilizing the high-frequency impact, periodic contact separation and strong plastic deformation of the surface layer of the workpiece 4 by the tool 1, a gradient fine grain layer is induced in situ in the machining sub-surface layer.

[0039] Specifically, an elliptical ultrasonic vibration system 7 is installed on a three-axis ultra-precision single-point diamond turning machining center, and a single-crystal diamond tool 1 is used for cutting. The elliptical ultrasonic vibration system 7 enables the tool 1 to generate high-frequency vibrations simultaneously in the cutting direction and the depth of cut direction, forming an elliptical motion trajectory.

[0040] Preferably, the elliptical ultrasonic vibration system 7 can generate arbitrary peak amplitudes of 0–4 μm in both bending and longitudinal vibration directions, with a fixed vibration frequency of 39.7 kHz. After the tool 1 vibrates in the combined cutting direction and depth of cut, the actual cutting trajectory of the tool tip relative to the surface of the workpiece 4 changes from conventional continuous cutting to high-frequency intermittent elliptical trajectory cutting, thereby forming microstructures with specific geometric features and spatial distribution patterns on the surface of the workpiece 4.

[0041] In this embodiment, the preferred process parameters for elliptical ultrasonic vibration-assisted turning are: spindle speed 1500 rpm, X-axis feed rate 3 mm / min, and Z-axis depth of cut 5 μm; the tool 1 is simultaneously vibrated along the cutting direction and depth of cut, wherein the amplitude in the cutting direction is preferably 4 μm, and the amplitude in the depth of cut is preferably 1–4 μm. By adjusting the amplitude in the depth of cut, functional surface microstructures with different morphological characteristics can be obtained. For example, when the amplitude in the depth of cut is small, the machined surface forms a relatively discrete micro-pit structure; when the amplitude in the depth of cut increases to a medium range, the surface gradually exhibits a scaly or overlapping microstructure; when the amplitude in the depth of cut further increases, a more obvious and regular grid-like or interlaced surface texture can be formed. Therefore, this invention can achieve active control over the morphology, scale, and distribution of the microstructure on the polycrystalline copper surface by adjusting the amplitude of elliptical ultrasonic vibration, thereby meeting the design requirements of different functional surfaces.

[0042] Furthermore, during elliptical ultrasonic vibration-assisted turning, due to the high-frequency intermittent contact between the tool 1 and the workpiece 4, the surface material of the workpiece 4 is subjected to periodic impacts, shearing, and extrusion in a very short time. This results in high strain, strain rate, and complex alternating stress states in localized areas, promoting the proliferation, entanglement, and rearrangement of dislocations, and further inducing grain refinement in the subsurface structure. In the region near the machined surface, the load is most intense, leading to the highest degree of grain refinement. As the depth from the surface increases, the degree of plastic deformation gradually weakens, and the grain size gradually increases, thus forming a gradient fine-grained layer structure that gradually transitions from the surface to the interior in the machined subsurface. This gradient fine-grained layer helps to reduce the anisotropic deformation response of polycrystalline copper during subsequent material removal processes and improves the hardness, wear resistance, and structural stability of the machined surface, thereby achieving a synergistic unity between functional surface morphology control and surface performance enhancement.

[0043] In this embodiment, the rake angle of the single-crystal diamond tool 1 is preferably 10°, the clearance angle is preferably 0°, and the cutting edge radius is preferably 2μm. By combining these parameters, significant surface tissue modification and better surface texture quality can be achieved while ensuring the stability of elliptical ultrasonic vibration loading.

[0044] Among them, the spectral confocal sensor integrated into the ultra-precision machining center is used to perform in-situ measurements on the machined surface to obtain key parameters such as surface shape error and surface roughness, so as to realize real-time evaluation of machining quality.

[0045] Specifically, after machining, the quality of the machined surface can be inspected in situ without disassembling the workpiece 4. Preferably, a spectral confocal sensor integrated into the ultra-precision turning machining center is used to perform non-contact scanning measurement of the surface. By analyzing the wavelength shift of reflected light, this sensor can obtain high-resolution three-dimensional morphology data of the workpiece 4 surface, based on which surface shape error, contour, surface roughness, and geometric parameters of functional microstructures, such as microstructure depth, width, periodicity, and distribution uniformity, can be further extracted.

[0046] When further evaluation of the surface modification effect is needed, the microstructure and mechanical properties of the processed samples can be characterized. For example, electron backscatter diffraction can be used to analyze the grain morphology, grain size distribution, and grain boundary characteristics of the surface and subsurface regions to verify the formation of the gradient fine grain layer; nanoindentation technology can be used to test the surface hardness and elastic modulus to evaluate the improvement effect of the process of the present invention on the surface properties of polycrystalline copper.

[0047] As an optional implementation, in the pretreatment step 4, the surface of the workpiece 4 is sanded with sandpaper, then mechanically polished, and finally ultrasonically cleaned.

[0048] Specifically, the polycrystalline copper workpiece 4 to be processed is pretreated to remove the original surface oxide layer, contaminants and surface damage layer introduced by the previous processing, so as to obtain a smooth and clean surface to be processed, which provides the basic conditions for subsequent high-quality functional surface processing.

[0049] Specifically, a polycrystalline copper sample was selected as workpiece 4 to be processed. To reduce the influence of the original surface condition of workpiece 4 on the subsequent ultra-precision machining results, workpiece 4 was first pretreated.

[0050] First, the surface of workpiece 4 is initially ground using sandpaper, preferably wet grinding under running water conditions, to suppress copper shavings adhesion and localized temperature rise. The sandpaper grit is preferably 2000 mesh. Grinding continues until uniform, fine, and consistent grinding marks are formed on the surface of workpiece 4, without obvious coarse scratches.

[0051] Subsequently, workpiece 4 is mechanically polished. The polishing equipment can be a metallographic sample polishing machine. The polishing cloth is preferably made of short-pile and slightly soft material. The polishing speed is preferably 200 rpm. The polishing pressure is preferably 0.15 MPa. The polishing abrasive is preferably a diamond spray polishing agent with a particle size of 2.5 μm. The polishing fluid can be a water-based suspension.

[0052] Finally, workpiece 4 is placed in a standard laboratory ultrasonic cleaner for cleaning. Anhydrous ethanol is preferred as the cleaning solvent, and the cleaning time is preferably 5 minutes. After cleaning, the surface of workpiece 4 is dried with low-pressure nitrogen to remove residual liquid and particulate contaminants. Through the above pretreatment, a smooth, clean workpiece 4 without significant scratches or contamination can be obtained.

[0053] By performing the above pretreatment on workpiece 4, a workpiece 4 with a smooth, clean surface and free from scratches and contamination is obtained.

[0054] As an optional implementation, during the process of aligning the tip of the tool 1 with the rotation center of the workpiece 4, a small amount of trial cutting is performed on the surface of the workpiece 4 to form fine cut marks; By observing the location of the fine cuts under a microscope and repeatedly adjusting the height of the tool holder, the tip trajectory of the tool 1 is made to pass precisely through the center of rotation of the workpiece 4.

[0055] The pre-treated polycrystalline copper workpiece 4 is clamped in the ultra-precision turning system, and tool setting and machining coordinate establishment are completed to ensure the stability and consistency of cutting depth, feed trajectory and vibration loading state in subsequent machining processes.

[0056] Specifically, the pre-treated polycrystalline copper workpiece 4 is clamped in an ultra-precision single-point diamond turning machining center. A cylindrical vacuum chuck can be used as the clamping fixture. Before clamping, it is preferable to trim the chuck's adsorption surface to reduce end-face runout and improve flatness, ensuring the rotational accuracy and surface finish consistency of workpiece 4 during subsequent machining.

[0057] In this embodiment, a three-axis ultra-precision single-point diamond turning machining center is used for machining. The minimum position resolution of this machining center is preferably 1 μm, the maximum spindle speed is preferably 2500 rpm, the system stiffness is preferably greater than 100 N / μm, the guide rail parallelism is preferably 0.03 / 700 mm, the straightness of the guide rail in the vertical plane is preferably 0.015 / 250 mm, and the axial and radial runout of the spindle is preferably less than 50 nm. To ensure the accurate relative position of the tool tip and the workpiece 4's rotation center, the tool setting process preferably uses a trial cutting method. This involves first making a small trial cut on the end face of the workpiece 4 to form a fine nick, then observing the nick position under a microscope. By repeatedly adjusting the tool holder height, the tool tip trajectory is made to precisely pass through the spindle rotation center line, thereby completing the precision tool setting.

[0058] Then, a trial cut method is used in the tool setting process to accurately determine the position of the tool tip. The specific operation is as follows: a small trial cut is made on the four end faces of the workpiece to form a fine cut mark; then the position of the cut mark is observed under a microscope, and the tool holder height is repeatedly adjusted to make the tool tip trajectory accurately pass through the spindle rotation center line, thereby establishing the accurate spatial relationship between the tool tip and the spindle rotation center.

[0059] Finally, roughing and finishing processes are used to eliminate the influence of clamping error on the turning results of polycrystalline copper workpiece 4, so as to ensure that the subsequent machining surface is flat and without tilt, and thus ensure that the cutting depth is consistent during the turning experiment.

[0060] The roughing parameters are as follows: spindle speed is 1500 rpm, constant feed rate along the X-axis is 6 mm / min, and constant depth of cut along the Z-axis is 10 μm.

[0061] The finishing turning parameters are as follows: spindle speed is 1500 rpm, constant feed rate along the X-axis is 3 mm / min, and constant depth of cut along the Z-axis is 5 μm.

[0062] As an optional implementation, during the cleaning process of the workpiece 4 after processing, the workpiece 4 is ultrasonically cleaned to remove residual chips and cutting fluid, and then dried and cleaned and packaged.

[0063] Workpiece 4 was removed from the ultra-precision machining center and ultrasonically cleaned again to thoroughly remove residual chips and cutting fluid. It was then dried and cleanly packaged to ensure the surface quality of workpiece 4 and its reliability for subsequent use.

[0064] Specifically, after processing and inspection, workpiece 4 is disassembled from the ultra-precision machining center and post-processed. Preferably, workpiece 4 undergoes a second ultrasonic cleaning to thoroughly remove residual micro-chips, processing fluid, and adsorbed particles from the machining process. Anhydrous ethanol is preferred as the cleaning solvent. After cleaning, the surface of workpiece 4 is dried using low-pressure nitrogen gas. Finally, workpiece 4 is packaged and stored in a clean environment to prevent secondary contamination or mechanical damage to the prepared functional surface, ensuring its reliability for subsequent testing and use.

[0065] As an optional implementation, the vibration frequency is 39.7 kHz.

[0066] Furthermore, in step 3, elliptical ultrasonic vibration-assisted turning achieves active control of the geometric features of the microstructure of the machined surface by adjusting the vibration amplitude of the tool 1 in the cutting direction and the depth of cut direction. Different combinations of vibration amplitudes can correspond to the formation of surface microstructures with different morphological features, scale parameters and spatial distribution patterns to meet the application requirements of polycrystalline copper parts in terms of friction reduction and wear resistance, lubrication and fluid storage, heat transfer enhancement, optical control or interface function enhancement.

[0067] Furthermore, in step 3, elliptical ultrasonic vibration-assisted turning introduces a high-frequency alternating load into the polycrystalline copper surface layer, causing a higher dislocation density and significant plastic strain accumulation in localized areas of the material surface. This promotes grain refinement in the subsurface microstructure, forming a gradient fine-grained layer structure with gradually varying grain sizes at different depths from the machined surface. This gradient fine-grained layer improves the plastic deformation coordination of the polycrystalline copper surface layer, reduces the anisotropic machining response caused by differences in grain orientation during conventional turning, thereby reducing the tendency for surface defects to form and improving surface properties.

[0068] Furthermore, the processing method of the present invention can achieve coordinated control of the microstructure morphology of polycrystalline copper surface, the thickness of the subsurface gradient fine grain layer, and the overall surface performance by changing parameters such as vibration amplitude, frequency, feed rate, spindle speed, and cutting depth.

[0069] This invention utilizes the adjustability of the tool trajectory during elliptical ultrasonic vibration-assisted turning to form designable functional microstructures on the surface of polycrystalline copper. Simultaneously, high-frequency impact and periodic plastic loading of the tool induce in-situ formation of a gradient fine-grained layer in the machined subsurface. The former imparts specific functional properties to the surface, while the latter improves the surface microstructure and mechanical properties. Together, they achieve efficient manufacturing of high-quality functional surfaces on polycrystalline copper. Compared to the traditional off-site, step-by-step process of refining followed by turning, this invention completes surface texture construction and surface microstructure enhancement within the same clamping and machining platform, avoiding problems such as re-clamping errors, lengthy processes, and diminished refining effects. It possesses high process integration, control flexibility, and engineering application value.

[0070] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "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, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0071] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A polycrystalline metal surface treatment device for precision cutting assisted by ultrasonic vibration, characterized in that, include: The cutting tool (1) is used to cut the surface of the workpiece (4); The tool feed table (2) has a first base and a Z-axis moving end. The tool (1) is connected to the Z-axis moving end. The moving direction of the Z-axis moving end is perpendicular to the surface of the workpiece (4). The Z-axis moving end causes the tip of the tool (1) to act on the surface of the workpiece (4) at a set feed speed and feed depth. The elliptical ultrasonic vibration system (7) has a control end and a vibration end. The vibration end is connected to the cutting tool (1) so that the tip of the cutting tool (1) vibrates to form a cutting trajectory. The cutting trajectory is formed by the high-frequency vibration of the tip of the cutting tool (1) in the cutting direction and the depth of cut in the elliptical motion trajectory on the surface of the workpiece (4). The control end is used to control the vibration amplitude and vibration frequency of the tip of the cutting tool (1). The workpiece moving carrier (6) has a second base, an X-axis moving end and a rotating end. The rotating end is connected to the workpiece (4). The X-axis moving end is used to adjust the position of the workpiece (4). The rotating end is used to make the workpiece (4) rotate at a set speed. The moving direction of the X-axis moving end is perpendicular to the moving direction of the Z-axis moving end. A spectral confocal sensor is used to acquire three-dimensional topographic data of the surface of the workpiece (4), and the spectral confocal sensor is located on one side of the workpiece (4).

2. The ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment device according to claim 1, characterized in that, It also includes a force gauge (3) for obtaining the pressure value between the cutting tool (1) and the workpiece (4), and the force gauge (3) is set between the first base and the Z-axis moving end.

3. The ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment device according to claim 1, characterized in that, The rotating end is fixed to the workpiece (4) by a cylindrical vacuum suction cup.

4. The ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment device according to claim 1, characterized in that, The elliptical ultrasonic vibration system (7) enables the tip of the cutting tool (1) to generate a peak amplitude of 0 to 4 μm in both the bending vibration direction and the longitudinal vibration direction.

5. The ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment device according to claim 1, characterized in that, The front angle of the cutting tool (1) is 10° and the rear angle is 0°.

6. A method for surface treatment of polycrystalline metals, using the ultrasonic vibration-assisted precision cutting polycrystalline metal surface treatment apparatus according to any one of claims 1-5, characterized in that, Includes the following steps: The workpiece (4) is pretreated to make its surface smooth, clean, and free of scratches and contamination; The workpiece (4) is fixed on the rotating end, the tip of the cutting tool (1) is aligned with the rotation center of the workpiece (4), and a machining coordinate system is established with the rotation center as the origin. The feed rate, feed depth, vibration amplitude, vibration frequency and rotation speed are set according to the functional microstructure of the surface of the workpiece (4) to be processed; The three-dimensional morphology data of the processed surface is acquired in real time by the spectral confocal sensor, and the processing quality is evaluated. Clean the surface of the workpiece (4) after processing.

7. The polycrystalline metal surface treatment method according to claim 6, characterized in that, In the pretreatment step of the workpiece (4), the surface of the workpiece (4) is polished with sandpaper, and then the surface of the workpiece (4) is mechanically polished. Finally, the mechanically polished workpiece (4) is ultrasonically cleaned.

8. The polycrystalline metal surface treatment method according to claim 6, characterized in that, During the process of aligning the tip of the cutting tool (1) with the rotation center of the workpiece (4), a small amount of trial cutting is performed on the surface of the workpiece (4) to form fine cut marks; The location of the fine cuts was observed under a microscope. By repeatedly adjusting the height of the tool holder, the tip trajectory of the tool (1) was made to pass precisely through the rotation center of the workpiece (4).

9. The polycrystalline metal surface treatment method according to claim 6, characterized in that, During the cleaning process of the workpiece (4) after processing, the workpiece (4) after processing is ultrasonically cleaned to remove residual chips and cutting fluid, and then dried and cleaned and packaged.

10. The polycrystalline metal surface treatment method according to claim 6, characterized in that, The vibration frequency is 39.7 kHz.

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