Pyramid-nanograting composite texture ultrasonic vibration assisted machining method and tool holder device

Abstract

The application provides a pyramid-nano-grating composite texture ultrasonic vibration assisted machining method and a tool holder device. The machining tool holder comprises a conical transition amplitude transformer, a piezoelectric ceramic excitation group, a pre-tightening locking mechanism and a tool clamping assembly, adopts a hollow rigid structure and stably outputs axial high-frequency vibration. Through an orthogonal step-by-step ultrasonic vibration assisted machining method, after workpiece clamping and tool setting, the axial vibration of the coupled tool and the linear feeding motion of the machining platform are coupled, a first parallelly arranged V-shaped groove-nano-grating texture is machined; the workpiece is accurately rotated by 90 degrees to complete orthogonal indexing, the parameters are reset to machine a second orthogonal grating texture; the two-way orthogonal textures are cross-coupled to form an arrayed pyramid-nano-grating composite texture in situ. The application can effectively reduce the cutting force, inhibit chip adhesion, improve the size consistency and machining efficiency of micro-nano textures and support high-precision batch preparation of composite functional micro-nano textures of high-end optical devices.

Description

Technical Field

[0001] This invention relates to the fields of ultra-precision micro-nano machining and ultrasonic vibration cutting technology, specifically to an ultrasonic vibration-assisted machining method and tool holder device for a pyramid-nano grating composite texture. Background Technology

[0002] As micro-nano optical devices evolve towards multifunctional integration, single-dimensional planar nanogratings are no longer sufficient to meet the demands of complex optical manipulation. Pyramid-nanograting composite textures combine the antireflective, hydrophobic, and light scattering control properties of microscale pyramid structures with the diffraction frequency selection and structural color display functions of nanogratings, showing broad application prospects in structural color display, optical sensing, information anti-counterfeiting, and biomimetic functional surfaces. The low-cost, high-volume fabrication of high-performance composite micro-nano textures is a crucial research direction in the field of ultra-precision micro-nano manufacturing.

[0003] Currently, composite micro / nano textures are mostly fabricated using semiconductor processes such as photolithography, ion etching, and wet etching. While these methods can achieve high morphological accuracy, they suffer from drawbacks such as lengthy process flows, large equipment investment, and high processing costs. Furthermore, they are typically only suitable for a few semiconductor materials, such as silicon, and are difficult to efficiently fabricate large-area composite textures on various optical materials such as aluminum alloys, copper, and optical crystals. While ultra-precision turning and milling can achieve efficient machining of microtextures on large workpieces, the continuous contact between the tool and workpiece during the fabrication of nanoscale periodic composite textures results in high cutting forces, severe frictional adhesion, and a tendency for chip accumulation and rapid tool wear. This leads to problems such as poor grating period consistency, morphological distortion, and surface and subsurface damage.

[0004] Ultrasonic vibration-assisted machining (UHMA) technology, by superimposing high-frequency vibrations onto the cutting tool, can reduce cutting forces and improve the surface quality of the machined material, and has been applied in the field of precision machining. However, existing UHMA tool holders are mostly designed for single groove and planar machining, lacking a machining method adapted for orthogonal machining of pyramid-nano grating composite textures. Furthermore, ultrasonic tool holders generally suffer from problems such as stress concentration in the amplitude transformer, large assembly gaps in the piezoelectric components, low energy conversion efficiency, and insufficient vibration stability, making it difficult to guarantee dimensional consistency and morphological accuracy in the two-dimensional orthogonal machining of composite textures, and hindering the high-precision mass production of high-performance composite micro / nano textures. Summary of the Invention

[0005] (a) Purpose of the invention

[0006] To address the problems of lengthy processes, high manufacturing costs, and limited material compatibility in the fabrication of pyramid-nanograting composite textures in existing technologies, traditional mechanical cutting suffers from high cutting forces, rapid tool wear, and poor microstructure periodicity consistency, and existing ultrasonic vibration machining devices lack supporting orthogonal machining processes, have insufficient vibration stability, and are unable to guarantee the consistency of two-dimensional machining accuracy of composite textures, this invention provides an ultrasonic vibration-assisted machining method and tool holder device for pyramid-nanograting composite textures. This method can improve vibration stability and energy conversion efficiency, effectively improve the friction state between the tool and the workpiece, reduce cutting forces and tool wear, and significantly improve the machining efficiency and accuracy of composite textures.

[0007] (II) Technical Solution

[0008] The technical means employed in this invention are as follows:

[0009] An ultrasonic vibration-assisted machining tool holder with a pyramid-nanograting composite texture is characterized by comprising a conical transition amplitude transformer, a piezoelectric ceramic excitation group, a pre-tightening locking mechanism, a tool clamping assembly, an ultrasonic drive and control unit, a rear end cover, and a cutting tool. The machining tool holder features a hollow design, with the piezoelectric ceramic excitation group internally integrated and connected to the external ultrasonic drive and control unit. The end of the tool holder is a conical transition amplitude transformer, which is connected to the tool clamping assembly via a fastening structure. The tool clamping assembly holds the cutting tool. A pre-tightening locking mechanism connects the conical transition amplitude transformer, the piezoelectric ceramic excitation group, and the rear end cover, forming the main body of the machining tool holder capable of outputting high-frequency axial vibration.

[0010] Furthermore, the piezoelectric ceramic excitation assembly is composed of multiple piezoelectric ceramic sheets stacked along the thickness direction, with the polarization direction of each piezoelectric ceramic sheet consistent with the axis of the tool holder.

[0011] Furthermore, a pre-tightening locking mechanism is provided on the outside of the piezoelectric ceramic excitation group, including a lead screw and a locking nut. One end of the lead screw is directly connected to and fixed to the conical transition amplitude rod through a thread, and the other end passes through the piezoelectric ceramic excitation group and the rear end cover and is tightened by the locking nut to achieve gapless rigid clamping of each component.

[0012] Furthermore, the tool clamping assembly includes a tool chuck and a locking cap. The cutting tool is installed inside the tool chuck, and the tool can be coaxially clamped and fixed by tightening the locking cap externally.

[0013] Furthermore, the ultrasonic drive measurement and control unit includes a signal generator, a power amplifier, and a laser vibrometer, which are used to provide excitation signals to the machining tool holder and detect the vibration frequency and amplitude in real time to ensure dynamic control of vibration parameters.

[0014] This invention also discloses an ultrasonic vibration-assisted processing method for pyramid-nanograting composite textures, comprising the following steps:

[0015] Step 1: Clamp and position the workpiece to be processed on the processing platform and complete the rigid locking;

[0016] Step 2: Install the axial ultrasonic vibration machining tool holder onto the spindle end of the machining platform, load the V-shaped cutting tool into the tool clamping assembly at the front end of the tool holder and complete the coaxial locking to ensure the coaxiality of the tool and the tool holder;

[0017] Step 3: Drive the machining platform spindle to feed along the Z-axis, and coordinate with the X and Y-axis translation adjustments to bring the cutting tool tip close to the workpiece surface to be machined, thus completing the initial tool setting calibration;

[0018] Step 4: Start the ultrasonic drive and control unit, set the vibration frequency and target amplitude corresponding to the first machining direction, and excite the piezoelectric ceramic excitation group inside the tool holder to generate axial vibration. The vibration energy is amplified by the conical transition amplitude transformer and then transmitted to the tool tip. The laser vibration measurement unit collects the tool tip vibration parameters in real time and feeds back the control drive signal until the ultrasonic parameters meet the machining requirements.

[0019] Step 5: Set the first-axis cutting process parameters, and couple the axial vibration of the tool with the linear feed motion of the machining platform through the machining program to continuously machine multiple parallel first-axis V-grooves-nano grating composite textures on the workpiece surface;

[0020] Step Six: After the first machining direction is completed, turn off the ultrasonic drive measurement and control unit, raise the machining platform spindle to a safe height, drive the machining platform to rotate the workpiece precisely around the Z-axis by 90°, and complete the positioning and locking of the second machining direction;

[0021] Step 7: Turn on the ultrasonic drive measurement and control unit, set the ultrasonic vibration parameters and cutting process parameters corresponding to the second machining direction, reset the machining program, and machine the second V-groove-nano grating orthogonal to the first direction texture; the two orthogonal V-groove-nano gratings are cross-coupled to form an arrayed pyramid-nano grating composite texture on the workpiece surface;

[0022] Step 8: After all processing is completed, turn off the ultrasonic drive measurement and control unit and the feed axis of the processing platform in sequence, raise the spindle and unload the workpiece, and inspect the morphology, size, periodicity, surface quality and optical properties of the composite texture.

[0023] Furthermore, the rotational positioning accuracy of the machining platform is no less than ±5″, and the orthogonality deviation of the two-way texture is less than 0.05°. The cutting depth ranges from 1 μm to 10 μm, the feed rate ranges from 1 mm / min to 100 mm / min, and the grating period can be adjusted within the range of 200 nm to 20 μm.

[0024] Furthermore, the tip vibration frequency range of the single-crystal diamond V-shaped tool is 20 kHz to 40 kHz, and the amplitude range is 1 μm to 10 μm. The vibration mode output by the tool tip is not limited to one-dimensional axial vibration, but can be extended to two-dimensional or three-dimensional composite vibration, forming a controllable multi-dimensional cutting trajectory.

[0025] Furthermore, this processing method can achieve different grating spacings by adjusting the feed rate and ultrasonic frequency. By controlling cutting parameters such as cutting depth and texture spacing, various composite micro-nano texture arrays, such as triangular pyramid-nano gratings and trapezoidal pyramid-nano gratings, can be processed.

[0026] (III) Beneficial Effects

[0027] The above-described technical solution of the present invention has the following beneficial technical effects:

[0028] This invention proposes a method for fabricating pyramid-nanograting composite textures. Through two orthogonal ultrasonic vibration-assisted cutting processes, an arrayed pyramid-nanograting composite texture is directly formed in situ on the workpiece surface, replacing the traditional multi-step photolithography-etching composite process. This significantly shortens the process flow, is suitable for machining large-size workpieces, and substantially reduces the manufacturing cost of composite micro / nano textures. By employing a conical transition amplitude transformer, the stress distribution is more uniform compared to the traditional stepped amplitude transformer. Combined with a pull-rod type pre-tightening locking mechanism, the assembly gap between the piezoelectric component and the conical transition amplitude transformer and rear end cap is completely eliminated. The high-efficiency piezoelectric component and precision tool clamping structure are integrated on the tool holder, resulting in good tool tip vibration stability and uniform amplitude output, ensuring consistent fabrication of the micro / nano composite texture. This processing technology can significantly reduce cutting forces and tool wear, improving machining accuracy, surface quality, and processing efficiency. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a process flow diagram of the processing method for the pyramid-nanograting composite texture of the present invention.

[0031] Figure 2 This is a schematic diagram illustrating the principle of the pyramid-nanograting composite texture processing method of the present invention.

[0032] Figure 3This is a schematic diagram of the overall structure of the ultrasonic vibration-assisted machining tool holder with the pyramid-nano grating composite texture of the present invention.

[0033] Figure 4 This is a schematic diagram of the processing equipment for the pyramid-nanograting composite texture of the present invention.

[0034] Figure 5 This is a schematic diagram of the first-direction V-groove-nanograting texture and a color rendering effect diagram of the present invention.

[0035] Figure 6 This is a schematic diagram of the pyramid composite texture array formed by the two-way orthogonal intersection of the present invention.

[0036] In the diagram: 1. Cutting tool; 2. Locking cap; 3. Tool positioning block; 4. Conical transition amplitude transformer; 5. Fixed flange; 6. Piezoelectric ceramic excitation assembly; 7. Rear end cover; 8. Connecting screw; 9. Locking nut; 10. Electrode gasket; 11. Machining platform spindle; 12. Real-time monitoring controller; 13. Laser vibrometer; 14. Machining platform; 15. Machining workpiece; 16. Power amplifier; 17. Signal generator; Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.

[0038] like Figure 1 and Figure 2 As shown in the figure, this invention discloses a vibration-assisted fabrication method for pyramid-nanograting composite textures, comprising the following steps:

[0039] The vibration-assisted processing method and tool holder device for the pyramid-nanograting composite texture includes the following steps:

[0040] Step 1: Use the machining platform 14 to fix and clamp the workpiece 15 to be processed;

[0041] Step 2: Install the vibration-assisted machining tool holder on the machining platform spindle 11, select a V-shaped single crystal diamond tool as the cutting tool 1, and complete the tool clamping and locking.

[0042] Step 3: The moving machining platform spindle 11 feeds along the Z-axis, coordinating with the X and Y-axis translations to ensure the cutting tool 1 tip is close to the workpiece surface, thus completing the tool setting operation. Set the single cutting depth a. p;

[0043] Step 4: Start the signal generator 17 to output a sinusoidal excitation signal, turn on the power amplifier 16 to adjust the output voltage, drive the piezoelectric ceramic excitation group 6 to generate axial vibration, which is amplified by the conical transition amplitude transformer 4 and transmitted to the tool tip; turn on the laser vibration meter 13, focus the laser beam on the tool tip position, collect the vibration frequency and amplitude data in real time and transmit them to the real-time monitoring controller 12; fine-tune the drive frequency to make the tool holder work in a resonant state, and finally the tool tip amplitude is stably output.

[0044] Step 5: Set the X-axis feed speed v1 of the machining platform 14, set the vibration frequency f1 and vibration amplitude A1, and control the vibration of the cutting tool 1 and the X-axis feed motion to couple the vibration of the cutting tool 1 with the X-axis feed motion through the machining program, so as to continuously machine a parallel first-direction V-groove-nano grating texture on the surface of the workpiece 15.

[0045] Step Six: After the first machining direction is completed, the machining platform spindle 11 is raised to a safe height along the Z-axis, and the machining platform 14 is controlled to drive the workpiece 15 to rotate precisely 90° around the Z-axis to complete the positioning and locking of the second machining direction;

[0046] Step 7: Reset the ultrasonic vibration frequency f2, vibration amplitude A1 and cutting parameters to process a second V-groove-nano grating orthogonal to the first texture. After the two textures intersect, an arrayed pyramid-nano grating composite texture is formed on the surface of the workpiece 15.

[0047] Step 8: After processing is completed, turn off the power amplifier 16, signal generator 17 and real-time monitoring controller 12 in sequence, raise the spindle to the initial position and remove the processed workpiece 15, and perform consistency detection on the texture morphology.

[0048] like Figure 3As shown, the composite tool holder includes a cutting tool 1, a tool positioning block 3, a conical transition amplitude transformer 4, a fixed flange 5, a piezoelectric ceramic excitation assembly 6, a rear end cap 7, a connecting screw 8, and a locking nut 9. The piezoelectric ceramic sheets are stacked sequentially along the thickness direction to form the piezoelectric ceramic excitation assembly 6. One end of the connecting screw 8 is screwed into the central threaded hole at the tail of the conical transition amplitude transformer 4 through a precision thread, ensuring the coaxiality of the connecting screw 8 and the conical transition amplitude transformer 4. The piezoelectric ceramic excitation assembly 6 is inserted along the lead screw 8 and fitted to the rear end face of the conical transition amplitude transformer 4. An electrode gasket 10 is connected in the middle, followed by the rear end cover 7. A locking nut 9 is screwed into the end of the lead screw 8 and tightened with a certain torque to ensure a tight fit between the conical transition amplitude transformer 4, the piezoelectric ceramic excitation assembly 6, and the rear end cover 7 without any gaps, eliminating vibration energy loss caused by assembly gaps. The tool positioning block 3 is installed in the clamping holes on both sides of the front end of the conical transition amplitude transformer 4. The single-crystal diamond cutting tool 1 is installed and positioned through the tool positioning block 3. The outer locking cap 2 is tightened to complete the coaxial clamping of the tool. The integral tool holder is fixed to the machining platform spindle 11 via the fixing flange 5.

[0049] like Figure 4 As shown, the ultrasonic vibration-assisted machining tool holder has an external control system and an online monitoring system, including a real-time monitoring controller 12, a laser vibrometer 13, a power amplifier 16, and a signal generator 17. The workpiece 15 is fixed on the machining platform, and the tool holder is clamped at the end of the machining platform spindle. The signal generator 17 outputs a sinusoidal excitation waveform, which is amplified by the power amplifier 16 and drives the piezoelectric assembly of the tool holder to generate axial vibration. The laser vibrometer 13 non-contactly collects the vibration signal of the tool tip and feeds it back to the real-time monitoring controller 12 to realize closed-loop control of vibration parameters.

[0050] like Figure 5 As shown, the V-shaped diamond cutting tool 1 processes V-groove nanogratings with different periods under vibration assistance. Under the condition of a certain ultrasonic vibration frequency, by adjusting the feed speed v, gratings with two different spacings, d1 and d2 can be achieved. The resulting nanograting samples show different macroscopic structural colors in the grating regions with different spacings.

[0051] like Figure 6 As shown, by adjusting the cutting distance L and cutting depth a of the V-shaped diamond cutting tool 1... p This method allows for the flexible fabrication of pyramidal composite textures with varying morphologies. Using a larger cutting distance L1, orthogonal cross-machining produces a triangular pyramid with a height of h1. Reducing the cutting distance to L2 yields a miniature triangular pyramid with a correspondingly lower height of h2, resulting in a denser pyramid arrangement. Increasing the cutting distance L3 allows for the orthogonal machining of a trapezoidal pyramid with a flat top and a top width of b1. Due to the versatility of the ultrasonic vibration-assisted machining method, machining parameters can be selected according to actual processing requirements.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A tool holder for ultrasonic vibration-assisted machining with a pyramid-nanograting composite texture, characterized in that, The machining tool holder includes a conical transition amplitude transformer, a piezoelectric ceramic excitation assembly, a pre-tightening locking mechanism, a tool clamping assembly, an ultrasonic drive and control unit, a rear end cover, and a cutting tool. The machining tool holder has a hollow design, with the piezoelectric ceramic excitation assembly built into the tool holder and connected to the external ultrasonic drive and control unit. The end of the tool holder is a conical transition amplitude transformer, which is connected to the tool clamping assembly through a fastening structure. The tool clamping assembly holds the cutting tool. The pre-tightening locking mechanism connects the conical transition amplitude transformer, the piezoelectric ceramic excitation assembly, and the rear end cover, together forming the main body of the machining tool holder capable of outputting high-frequency axial vibration.

2. The ultrasonic vibration-assisted machining tool holder with a pyramid-nanograting composite texture according to claim 1, characterized in that, The piezoelectric ceramic excitation group is assembled by stacking multiple piezoelectric ceramic sheets along the thickness direction, and the polarization direction of each piezoelectric ceramic sheet is consistent with the axial direction of the tool holder.

3. The ultrasonic vibration-assisted machining tool holder with a pyramid-nanograting composite texture according to claim 1, characterized in that, The piezoelectric ceramic excitation group is provided with a pre-tightening locking mechanism on the outside, including a lead screw and a locking nut. One end of the lead screw is directly connected to the fixed conical transition amplitude rod by a thread, and the other end passes through the piezoelectric ceramic excitation group and the rear end cover and is tightened by the locking nut to achieve gapless rigid clamping of each component.

4. The ultrasonic vibration-assisted machining tool holder with a pyramid-nanograting composite texture according to claim 1, characterized in that, The tool clamping assembly includes a tool chuck and a locking cap. The cutting tool is installed in the tool chuck, and the tool can be coaxially clamped and fixed by tightening the outer locking cap.

5. The ultrasonic vibration-assisted machining tool holder with a pyramid-nanograting composite texture according to claim 1, characterized in that, The ultrasonic drive measurement and control unit includes a signal generator, a power amplifier, and a laser vibrometer, which are used to provide excitation signals to the machining tool holder and detect the vibration frequency and amplitude in real time.

6. A method for ultrasonic vibration-assisted processing of pyramid-nanograting composite textures, characterized in that, The ultrasonic vibration-assisted machining of the tool holder using the pyramid-nanograting composite texture as described in any one of claims 1 to 5 includes the following steps: Step 1: Clamp and position the workpiece to be processed on the processing platform and complete the rigid locking; Step 2: Install the axial ultrasonic vibration assisted machining tool holder onto the spindle end of the machining platform, load the cutting tool into the tool clamping assembly at the front end of the tool holder and complete the coaxial locking; Step 3: Drive the machining platform spindle to feed along the Z-axis, and coordinate with the X and Y-axis translation adjustments to bring the tip of the V-shaped cutting tool close to the workpiece surface to be machined, thus completing the initial tool setting calibration; Step 4: Start the ultrasonic drive and control unit, set the vibration frequency and target amplitude corresponding to the first machining direction, and excite the piezoelectric ceramic excitation group inside the tool holder to generate axial vibration. The vibration energy is amplified by the conical transition amplitude transformer and then transmitted to the tool tip. The laser vibration measurement unit collects the tool tip vibration parameters in real time and feeds back the control drive signal until the ultrasonic parameters meet the machining requirements. Step 5: Set the first-axis cutting process parameters, and couple the axial vibration of the tool with the linear feed motion of the machining platform through the machining program to continuously machine multiple parallel first-axis V-grooves-nano grating composite textures on the workpiece surface; Step Six: After the first machining direction is completed, turn off the ultrasonic drive measurement and control unit, raise the machining platform spindle to a safe height, drive the machining platform to rotate the workpiece precisely around the Z-axis by 90°, and complete the positioning and locking of the second machining direction; Step 7: Turn on the ultrasonic drive measurement and control unit, set the ultrasonic vibration parameters and cutting process parameters corresponding to the second machining direction, reset the machining program, and machine the second V-groove-nano grating orthogonal to the first direction texture; the two orthogonal V-groove-nano gratings are cross-coupled to form an arrayed pyramid-nano grating composite texture on the workpiece surface; Step 8: After all processing is completed, turn off the ultrasonic drive measurement and control unit and the feed axis of the processing platform in sequence, raise the spindle and unload the workpiece, and inspect the morphology, size, periodicity, surface quality and optical properties of the composite texture.

7. The ultrasonic vibration-assisted processing method for the pyramid-nanograting composite texture according to claim 6, characterized in that, The machining platform has a rotational positioning accuracy of no less than ±5″, an orthogonal angle deviation of less than 0.05° for two-way texture, a cutting depth range of 1 μm to 10 μm, a feed rate range of 1 mm / min to 100 mm / min, and a grating period that can be adjusted in the range of 200 nm to 20 μm.

8. The ultrasonic vibration-assisted processing method for the pyramid-nanograting composite texture according to claim 6, characterized in that, The cutting tool is a single-crystal diamond V-shaped tool with a tip vibration frequency range of 20 kHz to 40 kHz and an amplitude range of 1 μm to 10 μm. The tip outputs one-dimensional axial vibration or two-dimensional / three-dimensional composite vibration to form a controllable multi-dimensional cutting trajectory.

9. The ultrasonic vibration-assisted processing method for the pyramid-nanograting composite texture according to claim 6, characterized in that, The processing method can achieve different grating spacings by adjusting the feed rate and ultrasonic frequency; by controlling cutting parameters such as cutting depth and texture spacing, it can process various composite micro-nano texture arrays such as triangular pyramid-nano gratings and trapezoidal pyramid-nano gratings.

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