Method for processing multi-stage microstructure on surface of difficult-to-machine material based on ultrasonic milling

Abstract

The application discloses a processing method of a multistage microstructure on a hard-to-machine material surface based on ultrasonic milling, which comprises the following steps: S1, setting processing parameters; and S2, applying a periodic vibration track to a tool tip to process a multistage microstructure on a workpiece, wherein the periodic vibration track is superimposed by longitudinal-torsional ultrasonic vibration composed of a longitudinal ultrasonic vibration along an axial direction and a torsional ultrasonic vibration along a cutting speed direction of the tool and a periodic low-frequency modulation motion different from the frequency of the longitudinal-torsional ultrasonic vibration, the low-frequency modulation motion generates a first-stage microstructure, the longitudinal-torsional ultrasonic vibration generates a second-stage microstructure, and the second-stage microstructure is smaller than the first-stage microstructure and forms the multistage microstructure with the first-stage microstructure. The application has high processing efficiency, good quality and low cost, and is suitable for processing of complex microstructures on a hard-to-machine material surface.

Description

Technical Field

[0001] This invention relates to the field of machining technology for multi-level microstructures on the surface of difficult-to-machine materials, and particularly to a machining method for multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling. Background Technology

[0002] Difficult-to-machine materials have wide applications in various fields due to their unique physical and chemical properties. For example, titanium alloys, with their high strength, low density, corrosion resistance, and strong biocompatibility, are commonly used in implants such as artificial joints, aircraft engine components in the aerospace field, and in the chemical and automotive industries. Fabricating microstructures on difficult-to-machine materials can further enhance their performance. Different microstructures can alter the surface morphology of difficult-to-machine materials, improve their physicochemical properties and corrosion resistance, and enhance their performance in various applications. For instance, in the field of waste heat recovery, microstructures can increase the material's surface area and change its wettability, thereby improving heat exchange efficiency and promoting waste heat recovery. However, in many application scenarios, conventional single-level microstructures are insufficient to meet performance requirements, necessitating the fabrication of multi-level microstructures.

[0003] Therefore, researching efficient fabrication processes for complex, multi-level microstructures on the surfaces of difficult-to-machine materials is crucial. Currently, surface microstructure fabrication is mainly achieved through non-mechanical methods, such as chemical etching, photolithography, electrical discharge machining / electrochemical machining, and laser / ion beam etching. However, these methods suffer from limitations such as limited available materials, complex engineering procedures, low manufacturing efficiency, expensive equipment, demanding process conditions, and environmental pollution, making them impractical for the fabrication of complex, multi-level microstructures on the surfaces of difficult-to-machine materials. Machining, represented by servo-driven metal cutting, can efficiently and cost-effectively manufacture high-precision surface microstructures, offering significant advantages. However, due to the bandwidth limitations of servo-driven cutting, the resolution of the fabricated microstructures is generally only a few hundred micrometers, hindering flexible microstructure construction. Furthermore, most current multi-level microstructure fabrication methods process different levels of microstructures step-by-step, further limiting processing efficiency. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to propose a machining method for multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling, which has high machining efficiency, good quality, low cost, and is suitable for machining complex microstructures on the surface of difficult-to-machine materials.

[0005] The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to embodiments of the present invention includes the following steps:

[0006] S1: Set processing parameters;

[0007] S2: Apply a periodic vibration trajectory to the tip of the cutting tool to machine a multi-level microstructure on the workpiece. The periodic vibration trajectory is composed of a longitudinal-torsional ultrasonic vibration consisting of a longitudinal ultrasonic vibration along the axial direction and a torsional ultrasonic vibration along the cutting speed direction of the cutting tool, and a periodic low-frequency modulated motion with a frequency different from that of the longitudinal-torsional ultrasonic vibration. The low-frequency modulated motion generates a primary microstructure, and the longitudinal-torsional ultrasonic vibration generates a secondary microstructure. The scale of the secondary microstructure is smaller than that of the primary microstructure and together with the primary microstructure constitutes the multi-level microstructure.

[0008] The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling, according to an embodiment of the present invention, can be performed on a five-axis ultrasonic milling device. The workpiece is pre-milled to make its surface flat. A piezoelectric driven ultrasonic system is installed on the five-axis ultrasonic milling device, machining parameters are set, and a periodic vibration trajectory is modulated using the piezoelectric driven ultrasonic system and applied to the tool tip. Depending on the different multi-level microstructure characteristics, by setting the machining parameters and applying the periodic vibration trajectory to the tool tip, longitudinal-torsional ultrasonic milling with periodically varying amplitude is performed on the pre-milled surface of the workpiece. The periodic vibration trajectory is composed of a longitudinal-torsional ultrasonic vibration consisting of a longitudinal ultrasonic vibration along the axial direction and a torsional ultrasonic vibration along the cutting speed direction of the tool, and a periodic low-frequency modulated motion with a frequency different from the longitudinal-torsional ultrasonic vibration. That is, the periodic vibration trajectory is composed of the superposition of three longitudinal ultrasonic vibrations, a torsional ultrasonic vibration, and a low-frequency modulated motion. The longitudinal ultrasonic vibration and the torsional ultrasonic vibration are coupled to form the longitudinal-torsional ultrasonic vibration, which is a high-frequency vibration, while the low-frequency modulated motion is a low-frequency vibration. Therefore, low-frequency modulated motion generates primary microstructures, and longitudinal-torsional ultrasonic vibration generates secondary microstructures. The scale of the secondary microstructures is smaller than that of the primary microstructures, and they combine with the primary microstructures to form corresponding complex multi-level microstructures with different geometric features. Thus, the ultrasonic milling-based method for machining multi-level microstructures on the surface of difficult-to-machine materials according to this invention can efficiently and cost-effectively produce complex multi-level microstructures. Due to the periodic separation between the tool and the workpiece during ultrasonic machining, the contact and friction between the tool and the workpiece can be effectively reduced, thereby lowering cutting force and cutting temperature, suppressing microcrack formation, and improving machining quality. Therefore, it is suitable for machining difficult-to-machine materials.

[0009] The ultrasonic milling-based method for machining multi-level microstructures on the surface of difficult-to-machine materials has the following advantages: First, it solves the problem that existing machining technologies cannot directly and efficiently machine multi-level complex microstructures on the surface of difficult-to-machine materials. Based on the principle of ultrasonic vibration-assisted machining, it has the advantages of being easy to implement, having high machining efficiency, and low cost. Second, it solves the problem of easily and effectively controlling the characteristics of multi-level microstructures on the surface. By controlling the relevant parameters of the periodic vibration trajectory and the machining parameters, the key geometric features of the complex multi-level microstructures on the workpiece surface can be controlled.

[0010] In some embodiments, the machining parameters include cutting speed, feed rate, and depth of cut; the vibration parameters of the periodic vibration trajectory include the frequency of the longitudinal torsional ultrasonic vibration, the frequency of the low-frequency modulation signal of the low-frequency modulation motion, the amplitude of the longitudinal ultrasonic vibration, the amplitude of the torsional ultrasonic vibration, the phase of the longitudinal ultrasonic vibration, and the phase of the torsional ultrasonic vibration.

[0011] In some embodiments, in the xyz coordinate system, the longitudinal ultrasonic vibration exists in the z-axis direction, and the torsional ultrasonic vibration exists in the xy plane; then the expression for the periodic vibration trajectory is as follows:

[0012]

[0013] in, The phase difference between the longitudinal ultrasonic vibration and the torsional ultrasonic vibration. The amplitude of the torsional ultrasonic vibration. Let r be the amplitude of the longitudinal ultrasonic vibration, and r be the tip radius of the cutting tool. The feed rate of the tool along the y-axis is [value missing]. The frequency of the low-frequency modulation signal is... The frequency of the longitudinal torsional ultrasonic vibration is given, and t is the processing time. The main spindle speed.

[0014] In some embodiments, the amplitude of the longitudinal ultrasonic vibration first increases from zero to a maximum within one low-frequency modulation signal period corresponding to the primary microstructure, and then gradually decreases to zero. The longitudinal displacement of the blade tip occurs multiple times within one period corresponding to the primary microstructure. / Each of these minimum values ​​corresponds to the same number of the secondary microstructures.

[0015] In some embodiments, the key geometric feature parameters of the multi-level microstructure include the length of the first-level microstructure, the width of the first-level microstructure, the width of the second-level microstructure, the spacing of the first-level microstructures in the cutting direction, and the spacing of the first-level microstructures in the feed direction.

[0016] In some embodiments, the spacing of the first-level microstructures in the cutting direction is mainly determined by the ratio of the cutting speed to the frequency of the low-frequency modulation signal; the spacing of the first-level microstructures in the feed direction is related to the feed speed; the length of the first-level microstructure is related to the spindle speed, the depth of cut, the tool tip radius, and the frequency of the low-frequency modulation signal; the width of the first-level microstructure is jointly determined by the tool tip radius and the depth of the first-level microstructure; the length of the second-level microstructure corresponds to the width of the first-level microstructure; the width of the second-level microstructure is determined by the spindle speed, the depth of cut, the tool tip radius, and the frequency of the longitudinal torsional ultrasonic vibration; and the cutting edge inclination angle of the tool corresponds to the angle between the directions of the first-level microstructures.

[0017] In some embodiments, the geometric key feature parameters of the multi-level microstructure are expressed as follows:

[0018]

[0019] in, S The spacing between the first-order microstructures in the cutting direction. d The spacing of the first-order microstructures in the feed direction. The length of the first-order microstructure is given. The width of the first-order microstructure. The width of the secondary microstructure is... The cutting speed is... The feed rate is... The spindle speed is... The radius of the blade tip is... The cutting depth is [the depth of cut]. The blade inclination angle, The actual cutting time for machining one of the aforementioned primary microstructures. The actual cutting time for machining one of the aforementioned secondary microstructures.

[0020] In some embodiments, the periodic vibration trajectory is generated by a piezoelectrically driven ultrasonic system.

[0021] In some embodiments, the parameters of the cutting tool include the tool material, tool shape, the tip radius, and the inclination angle.

[0022] In some embodiments, the material of the workpiece is a metallic material or a non-metallic material.

[0023] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0024] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0025] Figure 1 This is a schematic diagram illustrating the principle of the ultrasonic milling-based method for machining multi-level microstructures on the surface of difficult-to-machine materials, according to an embodiment of the present invention.

[0026] Figure 2 This is a schematic diagram of the periodic vibration trajectory parameters and shape in the ultrasonic milling-based machining method for multi-level microstructures on the surface of difficult-to-machine materials, according to an embodiment of the present invention.

[0027] Figure 3 This is a schematic diagram of the shape and structural characteristic parameters of the multi-level microstructure obtained by the ultrasonic milling-based machining method for multi-level microstructures on the surface of difficult-to-machine materials according to an embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of the actual processing result of the ultrasonic milling-based method for processing multi-level microstructures on the surface of difficult-to-machine materials according to an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the surface wettability control results of the multi-level microstructure obtained by the ultrasonic milling-based machining method for multi-level microstructures on the surface of difficult-to-machine materials according to an embodiment of the present invention.

[0030] Figure label:

[0031] 1-Workpiece; 2-1-Longitudinal ultrasonic vibration; 2-2-Torsion ultrasonic vibration; 3-Tool; 4-Multi-level microstructure; 4-1-Primary microstructure; 4-2-Secondary microstructure; - Cutting speed; - Feed rate; DOC - Depth of cut; - Spindle speed; - First-order microstructure length; - First-order microstructure width; -Secondary microstructure width; - Edge inclination angle; S - Spacing of primary microstructures in the cutting direction; d - Feed direction primary microstructure spacing. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0033] The following is combined Figures 1 to 5This invention describes a method for processing multi-level microstructures 4 on the surface of difficult-to-machine materials based on ultrasonic milling, according to an embodiment of the present invention.

[0034] like Figures 1 to 3 As shown, the method for machining multi-level microstructures 4 on the surface of difficult-to-machine materials based on ultrasonic milling according to an embodiment of the present invention includes the following steps:

[0035] S1: Set processing parameters.

[0036] S2: Apply a periodic vibration trajectory to the tip of the tool 3 to machine a multi-level microstructure 4 on the workpiece 1. The periodic vibration trajectory is composed of a longitudinal-torsional ultrasonic vibration consisting of a longitudinal ultrasonic vibration 2-1 along the axial direction and a torsional ultrasonic vibration 2-2 along the cutting speed direction of the tool 3, and a periodic low-frequency modulation motion with a frequency different from the longitudinal-torsional ultrasonic vibration. The low-frequency modulation motion generates a first-level microstructure 4-1, and the longitudinal-torsional ultrasonic vibration generates a second-level microstructure 4-2. The scale of the second-level microstructure 4-2 is smaller than that of the first-level microstructure 4-1 and together with the first-level microstructure 4-1, they form a complex multi-level microstructure 4.

[0037] According to an embodiment of the present invention, the method for machining multi-level microstructures 4 on the surface of difficult-to-machine materials based on ultrasonic milling can be performed on a five-axis ultrasonic milling device. The workpiece 1 is pre-milled to make its surface flat. A piezoelectric driven ultrasonic system is installed on the five-axis ultrasonic milling device, machining parameters are set, and a periodic vibration trajectory is modulated using the piezoelectric driven ultrasonic system and applied to the tip of the tool 3. According to different multi-level microstructure 4 characteristic requirements, by setting machining parameters and applying a periodic vibration trajectory to the tip of the tool 3, longitudinal torsional ultrasonic milling with periodically varying amplitude is performed on the pre-milled surface of the workpiece 1. The periodic vibration trajectory is formed by superimposing a longitudinal-torsional ultrasonic vibration consisting of a longitudinal ultrasonic vibration 2-1 along the axial direction and a torsional ultrasonic vibration 2-2 along the cutting speed direction of the tool 3, and a periodic low-frequency modulated motion with a frequency different from the longitudinal-torsional ultrasonic vibration. In other words, the periodic vibration trajectory is formed by superimposing three longitudinal ultrasonic vibrations 2-1, a torsional ultrasonic vibration 2-2, and a low-frequency modulated motion. The longitudinal ultrasonic vibration 2-1 and the torsional ultrasonic vibration 2-2 are coupled to form the longitudinal-torsional ultrasonic vibration, which is a high-frequency vibration, while the low-frequency modulated motion is a low-frequency vibration. Therefore, the low-frequency modulated motion generates a primary microstructure 4-1, and the longitudinal-torsional ultrasonic vibration generates a secondary microstructure 4-2. The secondary microstructure 4-2 has a smaller scale than the primary microstructure 4-1 and combines with the primary microstructure 4-1 to form a corresponding complex multi-level microstructure 4 with different geometric features. Thus, the ultrasonic milling-based machining method for multi-level microstructures 4 on the surface of difficult-to-machine materials according to this embodiment of the invention can efficiently and cost-effectively machine complex multi-level microstructures 4. Due to the periodic separation between the tool 3 and the workpiece 1 during ultrasonic machining, the contact and friction between the tool 3 and the workpiece 1 can be effectively reduced, thereby reducing the cutting force and cutting temperature, suppressing the generation of microcracks, and improving the machining quality. Therefore, it is suitable for machining difficult-to-machine materials.

[0038] The ultrasonic milling method for processing multi-level microstructures 4 on the surface of difficult-to-machine materials according to the embodiments of the present invention has the following advantages: First, it solves the problem that existing processing technologies are unable to efficiently process multi-level complex microstructures directly on the surface of difficult-to-machine materials, and based on the principle of ultrasonic vibration-assisted processing, it has the advantages of being easy to implement, having high processing efficiency and low cost; Second, it solves the problem of easily and effectively controlling the characteristics of the multi-level microstructures 4 on the surface. By adjusting the relevant parameters of the periodic vibration trajectory and the processing parameters, the key geometric features of the complex multi-level microstructures 4 on the surface of the workpiece 1 can be controlled.

[0039] In some embodiments, the machining parameters include cutting speed, feed rate, and depth of cut; the vibration parameters of the periodic vibration trajectory include the frequency of the longitudinal torsional ultrasonic vibration, the frequency of the low-frequency modulation signal of the low-frequency modulation motion, the amplitude of the longitudinal ultrasonic vibration 2-1, the amplitude of the torsional ultrasonic vibration 2-2, the phase of the longitudinal ultrasonic vibration 2-1, and the phase of the torsional ultrasonic vibration 2-2. By changing the machining parameters and the vibration parameters of the periodic vibration trajectory, complex surface microstructures with different geometric characteristics can be obtained.

[0040] In some embodiments, in the xyz coordinate system, there exists longitudinal ultrasonic vibration 2-1 in the z-axis direction and torsional ultrasonic vibration 2-2 in the xy plane. Then, the expression for the periodic vibration trajectory is as follows:

[0041]

[0042] in, The phase difference between longitudinal ultrasonic vibration 2-1 and torsional ultrasonic vibration 2-2 is given. To reverse the amplitude of ultrasonic vibration 2-2, Let r be the amplitude of the longitudinal ultrasonic vibration 2-1, and r be the tip radius of the tool 3. Let be the feed rate of tool 3 along the y-axis. The frequency of the low-frequency modulation signal. The frequency of longitudinal torsional ultrasonic vibration.

[0043] The final modulated tool tip's periodic vibration trajectory in the plane formed by the cutting velocity direction and the z-axis is as follows: Figure 2 As shown, the amplitude of the longitudinal ultrasonic vibration 2-1 first increases from zero to a maximum within the low-frequency modulation signal period corresponding to the first-order microstructure 4-1, and then gradually decreases to zero. The longitudinal displacement of the blade tip occurs repeatedly within the period corresponding to the first-order microstructure 4-1. / Each of the following is a minimum value, and corresponds to the same number of secondary microstructures 4-2.

[0044] In some embodiments, the key geometric feature parameters of the multi-level microstructure 4 include the length of the first-level microstructure, the width of the first-level microstructure, the width of the second-level microstructure, the spacing of the first-level microstructures in the cutting direction, and the spacing of the first-level microstructures in the feed direction.

[0045] In this system, the spacing of the first-level microstructures in the cutting direction is mainly determined by the ratio of the cutting speed to the low-frequency modulation signal frequency; the spacing of the first-level microstructures in the feed direction is related to the feed speed; the length of the first-level microstructure is related to the spindle speed, depth of cut, tool tip radius, and low-frequency modulation signal frequency; the width of the first-level microstructure is jointly determined by the tool tip radius and the depth of the first-level microstructure; the length of the second-level microstructure corresponds to the width of the first-level microstructure; the width of the second-level microstructure is determined by the spindle speed, depth of cut, tool tip radius, and the frequency of longitudinal torsional ultrasonic vibration; the inclination angle of the tool 3 corresponds to the angle between the direction of the first-level microstructure 4-1. The size, distribution, and shape of the multi-level microstructure 4 can be controlled by changing various process parameters.

[0046] Specifically, the expressions for the geometric key feature parameters of the multi-level microstructure 4 are as follows:

[0047]

[0048] in, S The spacing of the first-order microstructures in the cutting direction. d The spacing of the first-order microstructure in the feed direction. The length of the first-order microstructure. The width of the first-order microstructure. The width of the secondary microstructure. For cutting speed, For feed rate, Main spindle speed The radius of the blade tip, For cutting depth, For the blade inclination angle, The actual cutting time for machining a first-order microstructure 4-1 is as follows: The actual cutting time for machining a secondary microstructure 4-2. Based on the expressions for the key geometric feature parameters of the multi-level microstructure 4, the size, distribution, and shape of the multi-level microstructure 4 can be controlled by changing various process parameters.

[0049] In some embodiments, the periodic vibration trajectory is generated by a piezoelectrically driven ultrasonic system.

[0050] Specifically, the piezoelectric-driven ultrasonic system includes a signal generator and an amplifier. Based on the different characteristics of the multi-level microstructures, the signal generator produces a specific electrical signal, which is then input to the power amplifier. After amplification, this signal becomes a periodic vibration trajectory. This periodic vibration trajectory is applied to the cutting tip, and the periodic vibration trajectory of the cutting tip in the plane formed by the cutting velocity direction and the z-axis is as follows: Figure 2 As shown.

[0051] In some embodiments, the parameters of the cutting tool 3 include the tool material, tool shape, tool tip radius, and cutting edge inclination angle. The parameters of the cutting tool 3 affect the specific morphology of the multi-level microstructure 4 on the machined surface. The tool material can be PCB or diamond, but is not limited to these.

[0052] In some embodiments, the material of workpiece 1 is a metallic or non-metallic material. For example, the material of workpiece 1 is TC4 titanium alloy, high-temperature alloy, high-temperature structural ceramic, composite material, etc. The material properties of workpiece 1 include the elasticity and plasticity of the material. The material properties of workpiece 1 will also have a certain influence on the specific surface morphology of the multi-level microstructure 4, but will not affect the key geometric features of the multi-level microstructure 4 such as periodicity.

[0053] Figure 4 This paper presents a set of multi-level microstructures 4 actually machined on the surface of TC4 (titanium alloy) workpiece 1, with corresponding machining parameters as follows: = 1000 Hz, ultrasonic frequency is 19500 Hz, spindle speed is 300 rpm, depth of cut DOC = 6 μm, feed rate 0.15 mm / r. Figure 4 (a) shows the white light observation results of the fabricated complex multi-level microstructure 4, which demonstrates the three-dimensional morphology of the fabricated multi-level microstructure 4. A clear multi-level microstructure 4 can be observed on the sample surface. The primary microstructure 4-1 is a pit structure, arranged in a close-packed, approximately parallelogram shape. Within each primary microstructure 4-1 pit, smaller secondary microstructures 4-2 are uniformly distributed in a ridge-like arrangement. The secondary microstructures 4-2 correspond to the pit characteristics of the primary microstructure 4-1, with their depth first increasing and then decreasing within a low-frequency cycle. Figure 4 (b) and Figure 4 (c) shows the electron microscopy observations magnified 100x and 1000x respectively, which show the microscopic morphology of the primary microstructure 4-1 and secondary microstructure 4-2.

[0054] The wettability of multi-level microstructure 4 surface samples with different structural parameters was measured, and the results are as follows: Figure 5 As shown. In this embodiment, the ultrasonic frequency is maintained at 19500 Hz, the depth of cut (DOC) is 6 μm, and the feed rate is... The low-frequency modulation frequency was changed to 0.15 mm / r. It can be seen that the processed complex multi-level microstructures 4 do not require post-processing to modify the surface energy, thus improving the hydrophobicity of the material surface. Furthermore, as the modulation frequency increases, the number of secondary microstructures 4-2 decreases, while their width and depth increase, and the corresponding material hydrophobicity gradually improves. This embodiment verifies that processing different complex multi-level microstructures 4 on the surface of titanium alloys can effectively control its wettability, and thus may be applied to fields such as enhanced condensation heat transfer. This confirms the effectiveness of the ultrasonic milling-based processing method for multi-level microstructures 4 on the surface of difficult-to-machine materials in this embodiment and demonstrates its application potential.

[0055] The ultrasonic milling-based method for processing multi-level microstructures 4 on the surface of difficult-to-machine materials according to embodiments of the present invention has the following advantages: First, it solves the problem that existing processing technologies cannot directly and efficiently process multi-level complex microstructures on the surface of difficult-to-machine materials, and based on the principle of ultrasonic vibration-assisted processing, it has the advantages of being easy to implement, having high processing efficiency, and low cost; Second, it solves the problem of easily and effectively controlling the characteristics of the multi-level microstructures 4 on the surface. By adjusting the relevant parameters of the periodic vibration trajectory and the processing parameters, the key geometric features of the complex multi-level microstructures 4 on the surface of the workpiece 1 can be controlled; Third, a set of multi-level microstructure samples were processed using different process parameters, and their wettability was measured, verifying that the ultrasonic milling-based method for processing multi-level microstructures 4 on the surface of difficult-to-machine materials according to embodiments of the present invention can process complex multi-level microstructures on the surface of difficult-to-machine materials, thereby achieving wettability control.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling, characterized in that, Includes the following steps: S1: Set processing parameters; S2: A periodic vibration trajectory is applied to the tip of the cutting tool to machine a multi-level microstructure on the workpiece. The periodic vibration trajectory is composed of a longitudinal-torsional ultrasonic vibration consisting of a longitudinal ultrasonic vibration along the axial direction and a torsional ultrasonic vibration along the cutting speed direction of the tool, and a periodic low-frequency modulated motion with a frequency different from the longitudinal-torsional ultrasonic vibration. The low-frequency modulated motion generates a primary microstructure, and the longitudinal-torsional ultrasonic vibration generates a secondary microstructure. The secondary microstructure has a smaller scale than the primary microstructure and together with the primary microstructure constitutes the multi-level microstructure. The machining parameters include cutting speed, feed rate, and depth of cut; the vibration parameters of the periodic vibration trajectory include the frequency of the longitudinal torsional ultrasonic vibration, the frequency of the low-frequency modulation signal of the low-frequency modulation motion, the amplitude of the longitudinal ultrasonic vibration, the amplitude of the torsional ultrasonic vibration, the phase of the longitudinal ultrasonic vibration, and the phase of the torsional ultrasonic vibration.

2. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to claim 1, characterized in that, In the xyz coordinate system, the longitudinal ultrasonic vibration exists in the z-axis direction, and the torsional ultrasonic vibration exists in the xy plane. The expression for the periodic vibration trajectory is as follows: in, The phase difference between the longitudinal ultrasonic vibration and the torsional ultrasonic vibration. The amplitude of the torsional ultrasonic vibration. Let r be the amplitude of the longitudinal ultrasonic vibration, and r be the tip radius of the cutting tool. The feed rate of the tool along the y-axis is [value missing]. The frequency of the low-frequency modulation signal is... The frequency of the longitudinal torsional ultrasonic vibration is given, and t is the processing time. The main spindle speed.

3. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to claim 2, characterized in that, The amplitude of the longitudinal ultrasonic vibration first increases from zero to a maximum within one cycle of the low-frequency modulation signal corresponding to the first-level microstructure, and then gradually decreases to zero. The longitudinal displacement of the blade tip occurs multiple times within one cycle corresponding to the first-level microstructure. / Each of these minimum values ​​corresponds to the same number of the secondary microstructures.

4. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to claim 2, characterized in that, The key geometric features of the multi-level microstructure include the length of the first-level microstructure, the width of the first-level microstructure, the width of the second-level microstructure, the spacing of the first-level microstructures in the cutting direction, and the spacing of the first-level microstructures in the feed direction.

5. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to claim 4, characterized in that, The spacing of the first-level microstructures in the cutting direction is determined by the ratio of the cutting speed to the frequency of the low-frequency modulation signal; the spacing of the first-level microstructures in the feed direction is related to the feed speed; the length of the first-level microstructure is related to the spindle speed, the depth of cut, the tool tip radius, and the frequency of the low-frequency modulation signal; the width of the first-level microstructure is jointly determined by the tool tip radius and the depth of the first-level microstructure; the length of the second-level microstructure corresponds to the width of the first-level microstructure; the width of the second-level microstructure is determined by the spindle speed, the depth of cut, the tool tip radius, and the frequency of the longitudinal torsional ultrasonic vibration; the cutting edge inclination angle of the tool corresponds to the angle between the directions of the first-level microstructures.

6. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to claim 5, characterized in that, The expressions for the geometric key feature parameters of the multi-level microstructure are as follows: in, S The spacing between the first-order microstructures in the cutting direction. d The spacing of the first-order microstructures in the feed direction. The length of the first-order microstructure is given. The width of the first-order microstructure. The width of the secondary microstructure is... The cutting speed is... The feed rate is... The spindle speed is... The radius of the blade tip is... The cutting depth is [the depth of cut]. The blade inclination angle, The actual cutting time for machining one of the aforementioned primary microstructures. The actual cutting time for machining one of the aforementioned secondary microstructures.

7. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to any one of claims 1-6, characterized in that, The periodic vibration trajectory is generated by a piezoelectric-driven ultrasonic system.

8. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to claim 5 or 6, characterized in that, The parameters of the cutting tool include the tool material, tool shape, tip radius, and cutting edge inclination angle.

9. The method for machining multi-level microstructures on the surface of difficult-to-machine materials based on ultrasonic milling according to any one of claims 1-6, characterized in that, The workpiece is made of either metallic or non-metallic materials.

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