Ultrasonic milling method for blazed gratings on metal surfaces

Abstract

This invention discloses an ultrasonic milling method for blazed gratings on metal surfaces, comprising the following steps: calculating the required clearance angle of the milling cutter based on the blaze angle of the blazed grating to be machined; calculating the required torsional and bending ratios of the milling cutter based on the length ratio of the cutting surface to the pressing surface of the blazed grating to be machined; calculating the frequency of the input signal, the feed rate of the milling cutter, and the spindle speed of the milling cutter based on the spacing of the blazed grating to be machined; calculating the predetermined angle between the axial direction of the milling cutter and the surface to be machined, and the milling depth based on the length of the blazed grating to be machined perpendicular to the feed direction; and calculating the amplitude of the input signal based on the height difference between the crests and troughs of the blazed grating to be machined. The ultrasonic milling method for blazed gratings on metal surfaces according to embodiments of this invention has advantages such as high processing efficiency, low machine tool precision requirements, and high degree of freedom.

Description

Technical Field

[0001] This invention relates to the field of grating processing technology, and more specifically, to a method for ultrasonic milling of blazed gratings on metal surfaces. Background Technology

[0002] The processing method for blazed gratings in related technologies employs mechanical scribing. This involves mounting the grating substrate on a dedicated scribing machine and using a diamond tool to reciprocate across the substrate surface, extruding and scribing it to obtain the designed grating morphology. However, this method requires high precision from the machining center and has low processing efficiency, making it difficult to efficiently process mass-produced products. Summary of the Invention

[0003] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for ultrasonic milling of blazed gratings on metal surfaces, which has the advantages of high processing efficiency, low machine tool precision requirements, and high degree of freedom.

[0004] To achieve the above objectives, an ultrasonic milling method for blazed gratings on metal surfaces is proposed according to an embodiment of the present invention. The ultrasonic milling method for blazed gratings on metal surfaces includes the following steps:

[0005] An ultrasonic milling apparatus is provided, the ultrasonic milling apparatus including at least a signal generator and an ultrasonic longitudinal-torsional composite vibration tool holder, the signal generator being adapted to generate an input signal, and the ultrasonic longitudinal-torsional composite vibration tool holder being connected to the signal generator;

[0006] The required clearance angle of the milling cutter is calculated based on the blaze angle of the blaze grating to be processed. The torsional and bending ratios of the milling cutter are calculated based on the ratio of the lengths of the cutting surface and the extrusion surface of the blaze grating to be processed in the feed direction of the milling cutter. The cutting surface is formed by the milling cutter cutting the blaze grating, and the extrusion surface is formed by the milling cutter extruding the blaze grating. The frequency of the input signal, the feed rate of the milling cutter, and the spindle speed of the milling cutter are calculated based on the spacing of the blaze grating to be processed. The predetermined angle between the milling cutter axis and the surface to be processed, as well as the milling depth, are calculated based on the length of the blaze grating to be processed perpendicular to the feed direction. The amplitude of the input signal is calculated based on the height difference between the crests and troughs of the blaze grating to be processed.

[0007] The end mill with the specified back angle and torsion ratio is selected and mounted on the ultrasonic longitudinal-torsion composite vibration tool holder, so that the axis of the end mill is at the specified angle to the surface to be machined. The input signal is generated by the signal generator, so that the end mill is fed according to the specified feed rate, the specified spindle speed and the specified milling depth.

[0008] The ultrasonic milling method for blazed gratings on metal surfaces according to embodiments of the present invention has the advantages of high processing efficiency, low machine tool precision requirements, and high degree of freedom.

[0009] In addition, the ultrasonic milling method for blazed gratings on metal surfaces according to the above embodiments of the present invention may also have the following additional technical features:

[0010] According to an embodiment of the present invention, the ultrasonic milling method for blazed gratings on metal surfaces further includes the following steps:

[0011] The surface to be processed is divided into an information area and other areas;

[0012] The information area and the other areas are machined at different spindle speeds.

[0013] According to one embodiment of the present invention, the ultrasonic longitudinal-torsional composite vibration tool holder is configured to cause the milling cutter to generate axial vibration, circumferential torsional vibration, and radial bending vibration when subjected to axial vibration.

[0014] According to one embodiment of the present invention, the outer peripheral surface of the ultrasonic longitudinal-torsional composite vibration tool holder is provided with a plurality of spaced spiral grooves, each of the spiral grooves extending spirally along the axial and circumferential directions of the ultrasonic longitudinal-torsional composite vibration tool holder.

[0015] According to one embodiment of the present invention, the ultrasonic milling apparatus further includes a phase difference detection device for detecting the phase difference of the milling cutter.

[0016] According to one embodiment of the present invention, the phase difference detection device includes two infrared distance sensors arranged perpendicularly to each other.

[0017] According to one embodiment of the present invention, the two infrared distance sensors are an axial infrared distance sensor and a radial infrared distance sensor, respectively, wherein the axial infrared distance sensor is oriented along the axial direction of the milling cutter, and the radial infrared distance sensor is oriented along the radial direction of the milling cutter.

[0018] According to one embodiment of the present invention, the milling cutter includes a body and a cutting edge, the cutting edge being disposed on the circumferential surface of the body.

[0019] According to one embodiment of the present invention, the cutting tool is a single-crystal diamond cutting tool.

[0020] According to one embodiment of the present invention, the ultrasonic longitudinal-torsional composite vibration tool holder includes a piezoelectric transducer and an amplitude transformer, wherein the piezoelectric transducer is adapted to convert an electrical signal into mechanical vibration, and the amplitude transformer is adapted to increase the amplitude of the mechanical vibration.

[0021] 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

[0022] 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:

[0023] Figure 1 This is a flowchart of an ultrasonic milling method for blazed gratings on a metal surface according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the ultrasonic milling apparatus for the ultrasonic milling method of blazed grating on metal surface according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the machining process of the ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the machining process of the ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the machining process of the ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of the structure of a blazed grating processed by the ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram of the structure of the surface to be processed in the ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention.

[0030] Reference numerals: 1. Ultrasonic milling device; 10. Signal generator; 20. Ultrasonic longitudinal-torsional composite vibration tool holder; 21. Helical groove; 30. Milling cutter; 31. Main body; 32. Cutting bit; 41. Axial infrared distance sensor; 42. Radial infrared distance sensor; 43. Computer; 2. Blazed grating; 3. Information area; 4. Other areas; 5. Cutting surface; 6. Extrusion surface. Detailed Implementation

[0031] This application is based on the inventor's discoveries and understanding of the following facts and problems:

[0032] Grating fabrication methods are divided into original gratings and replicated gratings. Replicated gratings require curing and demolding on the original grating, making grating fabrication on metal surfaces difficult. Original grating fabrication methods mainly include mechanical scribing, wet etching, and holographic ion beam processing. Holographic ion beam processing uses holographic interference lithography to create a mask, which is then used to etch the desired grating structure onto the substrate. This method is highly dependent on the mask, and the desired grating morphology can only be formed when the photoresist grating mask groove depth and aspect ratio meet the requirements. Wet etching utilizes the anisotropy of the etching rate of single-crystal silicon in an alkaline etching solution to etch the desired grating morphology. This method has extremely high material requirements for the grating substrate and a slow manufacturing rate, making it unsuitable for efficient fabrication of gratings on various material surfaces.

[0033] The processing methods for blazed gratings in related technologies employ mechanical scribing. This involves mounting the grating substrate on a dedicated scribing machine and using a diamond tool to reciprocate across the substrate surface, compressing and scribing to obtain the designed grating morphology. However, existing mechanical scribing methods often require extremely high-precision machining centers. Furthermore, they suffer from low processing efficiency when processing gratings at visible light wavelengths, hindering efficient mass production and limiting their industrial application. Moreover, they primarily target planar gratings and are ill-suited for processing curved gratings with higher degrees of freedom.

[0034] 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.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] The ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention is described below with reference to the accompanying drawings.

[0038] like Figures 1-7 As shown, the ultrasonic milling method for blazed gratings on metal surfaces according to an embodiment of the present invention includes the following steps:

[0039] An ultrasonic milling apparatus 1 is provided. The ultrasonic milling apparatus 1 includes at least a signal generator 10 and an ultrasonic longitudinal-torsional composite vibration tool holder 20. The signal generator 10 is adapted to generate an input signal, and the ultrasonic longitudinal-torsional composite vibration tool holder 20 is connected to the signal generator 10.

[0040] The required clearance angle of the milling cutter 30 is calculated based on the blaze angle b2 of the blaze grating 2 to be processed. The required torsional vibration a2 and bending vibration a3 ratios of the milling cutter 30 are calculated based on the ratio of the lengths of the cutting surface 5 and the extrusion surface 6 of the blaze grating 2 in the feed direction d of the milling cutter 30. The cutting surface 5 is formed by cutting the blaze grating 2 with the milling cutter 30, and the extrusion surface 6 is formed by extruding the blaze grating 2 with the milling cutter 30. The frequency of the input signal, the feed speed of the milling cutter 30, and the spindle speed of the milling cutter 30 are calculated based on the spacing f of the blaze grating 2 to be processed. The predetermined angle b1 between the axial direction of the milling cutter 30 and the surface to be processed, as well as the milling depth, are calculated based on the length of the blaze grating 2 perpendicular to the feed direction d. The amplitude of the input signal is calculated based on the height difference h between the crests and troughs of the blaze grating 2 to be processed.

[0041] A milling cutter 30 with the specified back angle and torsion ratio is selected and mounted on an ultrasonic longitudinal-torsion composite vibration tool holder 20, so that the axial direction of the milling cutter 30 is at a predetermined angle b1 with the surface to be machined. The input signal is generated by the signal generator 10, so that the milling cutter 30 feeds according to the specified feed rate, the specified spindle speed and the specified milling depth.

[0042] Specifically, during the machining process, the signal generator 10 generates the input signal, which is transmitted to the ultrasonic longitudinal-torsional composite vibration tool holder 20, causing the ultrasonic longitudinal-torsional composite vibration tool holder 20 to generate axial mechanical vibration, producing torsional vibration a3 and bending vibration a3. The milling cutter 30 performs machining under the combined action of multiple vibrations, in conjunction with the spindle rotation c and the spindle feed direction d. Each rotation of the milling cutter 30 around the spindle axis creates a pit on the surface to be machined, forming a blazed grating 2. During the machining process, the diamond tool moves along the vibration trajectory e1. Figure 5 As shown, when observed along the cross-section of the blazing grating 2, during the first half of the movement of the milling cutter 30 along the wavy trajectory e2, the surface to be machined is cut to remove a portion of the material, forming the cutting surface 5; during the second half of the movement, the milling cutter 30 retracts and interferes with the surface to be machined, and the flank face of the milling cutter 30 presses against the surface to be machined, forming the pressing surface 6.

[0043] The blaze angle of the blaze grating 2 refers to the angle between the extrusion surface 6 of the blaze grating 2 and the surface to be processed, such as... Figure 5 As shown in b2, since the extrusion surface 6 is formed by the back angle of the milling cutter 30, the blaze angle of the blaze grating is a replica of the back angle of the cutter. The blaze angle of the blaze grating 2 is determined by the back angle 24 of the cutter.

[0044] The ratio between torsional vibration a3 and bending vibration a2 determines the length ratio of the cutting surface 5 formed by cutting and the extrusion surface 6 formed by extrusion.

[0045] The lateral movement distance of the milling cutter 30 within a single vibration cycle determines the grating spacing f of the blazed grating 2. This lateral movement distance is determined by the feed rate d of the milling cutter 30 in the feed direction, the spindle speed c of the milling cutter 30, and the frequency of the input signal. The spindle speed has a much greater impact on the grating spacing f than the feed rate.

[0046] The length of the blazed grating 2 in the direction perpendicular to the feed direction d is determined by the predetermined angle b1 formed between the milling cutter 30 and the surface to be machined, as well as the depth of cut. Those skilled in the art will understand that the "depth of cut" refers to the degree of contact between the spindle and the surface to be machined.

[0047] The height h between the crests and troughs of the blazed grating 2 is determined by the amplitude of the bending vibration a2, which is proportional to the amplitude of the input signal.

[0048] Those skilled in the art will understand that the clearance angle and the torsion ratio of the milling cutter 30 are inherent properties of each milling cutter 30 and can be adjusted by selecting different milling cutters 30.

[0049] The formulas used in the above calculation process can be derived by those skilled in the art through existing formulas.

[0050] According to the ultrasonic milling method for blazed gratings on metal surfaces of the present invention, blazed gratings 2 are formed on the surface to be machined by applying ultrasonic frequency mechanical vibration a1 to a milling cutter 30, combined with the movement in the feed direction d and the spindle rotation c. In each vibration cycle, the milling cutter 30 machines one blazed grating 2 under the combined action of torsional vibration a2 and bending vibration a3. In the first half of the vibration cycle, material is removed by cutting to form a cutting surface 5; in the second half of the vibration cycle, an extrusion surface 6 is formed by extrusion between the flank face of the milling cutter 30 and the material. The geometry of each blazed grating 2 is composed of a replica of the tool tip trajectory and the flank face profile of the milling cutter 30. The blazing angle of the blazed grating 2 is determined by the clearance angle of the milling cutter 30, and the grating spacing f is mainly controlled by adjusting the spindle speed. The machining area of ​​the blazed grating 2 can be adjusted by adjusting the tilt angle b1 of the milling cutter 30 and the cutting depth. Combined with tool servo technology, patterned machining of the blazed grating 2 controlled at the pixel level can be achieved.

[0051] Furthermore, by utilizing ultrasonic milling to process blazed gratings, compared to mechanical scribing in related technologies, the blazed gratings 2 can be processed under high-frequency vibrations above 20 kHz, significantly improving the processing efficiency. Moreover, it requires lower precision from the machine tool, allowing it to be applied to machine tools with ordinary precision, thus reducing application costs. In addition, since milling offers greater freedom of movement than scribing, it can easily process free-form blazed gratings.

[0052] Therefore, the ultrasonic milling method for blazed gratings on metal surfaces according to embodiments of the present invention has advantages such as high processing efficiency, low machine tool precision requirements, and high degree of freedom.

[0053] The ultrasonic milling method for blazed gratings on metal surfaces according to a specific embodiment of the present invention is described below with reference to the accompanying drawings.

[0054] Advantageously, such as Figure 6 and Figure 7 As shown, the ultrasonic milling method for blazed gratings on metal surfaces further includes the following steps:

[0055] The surface to be processed is divided into information area 3 and other areas 4;

[0056] Information area 3 and other areas 4 are machined at different spindle speeds.

[0057] This facilitates the processing of optically encrypted information.

[0058] Specifically, such as Figure 6As shown, the blazed grating 2 can observe diffracted light i2 of different wavelengths depending on the incident light i1 and the viewing angle, visually manifesting as different colors. Simultaneously, when the illumination and viewing angle are fixed, the size of the grating spacing f also affects the wavelength of the diffracted light i2. Since the spindle speed has a much greater impact on the grating spacing f than the feed rate, the grating spacing f can be easily controlled by adjusting the spindle speed. Therefore, when the angle j1 between the incident light i1 and the normal to the grating plane and the angle j2 between the viewing angle and the normal to the machining surface are fixed, different structural colors can be machined on the workpiece. By combining tool servo technology and dividing the pattern into zones, and using corresponding machining parameters in different areas, the machining of structural color patterns on the workpiece surface can be achieved. Figure 7 As shown, to process text information, simply use two different spindle speeds in the other areas 4 and the information area 3 of the processing area to separate the diffraction orders of the two areas, thus completing the processing of the blazed grating 2 pattern. Simultaneously, when the diffraction orders of the two areas are high, the optical effects of the pattern information processed in this way are not significantly different, and the information will not be displayed. However, when the viewing angle changes to a lower diffraction order, the diffracted light from the information area 3 and the other area 4 will exhibit different colors due to the difference in diffraction orders, and the text information will be displayed, thereby completing the processing of optically encrypted information.

[0059] Specifically, such as Figure 2 and Figure 3 As shown, the ultrasonic longitudinal-torsional composite vibration tool holder 20 is constructed such that when subjected to axial vibration, the milling cutter 30 generates axial vibration a1, circumferential torsional vibration a3, and radial bending vibration a2. This facilitates the formation of the blazed grating 2.

[0060] More specifically, such as Figure 2 and Figure 3 As shown, the outer circumferential surface of the ultrasonic longitudinal-torsional composite vibration tool holder 20 is provided with a plurality of spaced spiral grooves 21, each spiral groove 21 extending spirally along the axial and circumferential directions of the ultrasonic longitudinal-torsional composite vibration tool holder 20. This allows the axial mechanical vibration generated by the input signal acting on the ultrasonic longitudinal-torsional composite vibration tool holder 20 to be partially converted into torsional vibration a3 when passing through the spiral groove 21, and to generate radial bending vibration a2.

[0061] Advantageously, such as Figure 2 As shown, the ultrasonic milling apparatus 1 also includes a phase difference detection device for detecting the phase difference of the milling cutter 30. This allows the phase difference of the vibration of the milling cutter 30 to be detected using the phase difference detection device, thus facilitating the control of the vibration of the milling cutter 30.

[0062] More advantageously, such as Figure 2As shown, the phase difference detection device includes two infrared distance sensors arranged perpendicularly to each other. This allows the two infrared distance sensors to detect the phase difference of vibrations in different directions.

[0063] Furthermore, such as Figure 2 As shown, the two infrared distance sensors are an axial infrared distance sensor 41 and a radial infrared distance sensor 42, respectively. The axial infrared distance sensor 41 is oriented along the axial direction of the milling cutter 30, and the radial infrared distance sensor 42 is oriented along the radial direction of the milling cutter 30. This allows for the detection of the phase difference of the milling cutter 30 in the axial and radial directions, respectively.

[0064] Specifically, the axial infrared distance sensor 41 and the radial infrared distance sensor 42 can be electrically connected to the computer 43, thereby facilitating the monitoring and measurement of the vibration of the milling cutter 30.

[0065] Figures 2-4 An ultrasonic milling apparatus 1 is shown as an ultrasonic milling method for ultrasonic milling of blazed gratings on metal surfaces according to some examples of the present invention. For example... Figures 2-4 As shown, the milling cutter 30 includes a body 31 and a cutting insert 32, with the cutting insert 32 disposed on the circumferential surface of the body 31. This facilitates the rotation of the body 31 to drive the cutting insert 32 to rotate circumferentially along the body 31, thereby facilitating the machining of recesses. Furthermore, the morphology of the recesses can be controlled by torsional vibration and bending vibration, thereby forming a blazed grating 2 within the recesses.

[0066] Optionally, the cutting tool 32 is a single-crystal diamond cutting tool. This ensures that the cutting tool 32 has sufficient structural strength.

[0067] Specifically, the ultrasonic longitudinal-torsional composite vibration tool holder 20 includes a piezoelectric transducer and an amplitude transformer. The piezoelectric transducer is adapted to convert electrical signals into mechanical vibrations, and the amplitude transformer is adapted to increase the amplitude of the mechanical vibrations. This allows the electrical signal emitted by the signal generator 10 to be converted into longitudinal mechanical vibrations by the piezoelectric transducer, and then amplified by the amplitude transformer before being transmitted to the milling cutter 30. Furthermore, the vibrations in all directions are generated by the same transducer, and generally there is no phase difference between the vibrations.

[0068] Other configurations and operations of the ultrasonic milling method for blazed gratings on metal surfaces according to embodiments of the present invention are known to those skilled in the art and will not be described in detail here.

[0069] 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.

[0070] 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 ultrasonic milling of blazed gratings on metal surfaces, characterized in that, Includes the following steps: An ultrasonic milling apparatus is provided, the ultrasonic milling apparatus including at least a signal generator and an ultrasonic longitudinal-torsional composite vibration tool holder, the signal generator being adapted to generate an input signal, and the ultrasonic longitudinal-torsional composite vibration tool holder being connected to the signal generator; The required clearance angle of the milling cutter is calculated based on the blaze angle of the blaze grating to be processed. The torsional and bending ratios of the milling cutter are calculated based on the ratio of the lengths of the cutting surface and the extrusion surface of the blaze grating to be processed in the feed direction of the milling cutter. The cutting surface is formed by the milling cutter cutting the blaze grating, and the extrusion surface is formed by the milling cutter extruding the blaze grating. The frequency of the input signal, the feed rate of the milling cutter, and the spindle speed of the milling cutter are calculated based on the spacing of the blaze grating to be processed. The predetermined angle between the milling cutter axis and the surface to be processed, as well as the milling depth, are calculated based on the length of the blaze grating to be processed perpendicular to the feed direction. The amplitude of the input signal is calculated based on the height difference between the crests and troughs of the blaze grating to be processed. The end mill with the specified back angle and the specified torsion ratio is selected and mounted on the ultrasonic longitudinal torsion composite vibration tool holder, so that the axis of the end mill is at the specified angle with the surface to be machined. The input signal is generated by the signal generator, so that the end mill is fed according to the specified feed rate, the specified spindle speed and the specified milling depth. The ultrasonic longitudinal-torsional composite vibration tool holder is designed to cause the milling cutter to generate axial vibration, circumferential torsional vibration, and radial bending vibration when subjected to axial vibration.

2. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 1, characterized in that, It also includes the following steps: The surface to be processed is divided into an information area and other areas; The information area and the other areas are machined at different spindle speeds.

3. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 1, characterized in that, The outer circumferential surface of the ultrasonic longitudinal-torsional composite vibration tool holder is provided with a plurality of spaced spiral grooves, each spiral groove extending spirally along the axial and circumferential directions of the ultrasonic longitudinal-torsional composite vibration tool holder.

4. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 1, characterized in that, The ultrasonic milling apparatus also includes a phase difference detection device for detecting the phase difference of the milling cutter.

5. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 4, characterized in that, The phase difference detection device includes two infrared distance sensors arranged perpendicularly to each other.

6. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 5, characterized in that, The two infrared distance sensors are an axial infrared distance sensor and a radial infrared distance sensor, respectively. The axial infrared distance sensor is oriented along the axial direction of the milling cutter, and the radial infrared distance sensor is oriented along the radial direction of the milling cutter.

7. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 1, characterized in that, The milling cutter includes a body and a cutting edge, with the cutting edge disposed on the circumferential surface of the body.

8. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 7, characterized in that, The cutting tool is a single-crystal diamond cutting tool.

9. The ultrasonic milling method for blazed gratings on metal surfaces according to claim 1, characterized in that, The ultrasonic longitudinal-torsional composite vibration tool holder includes a piezoelectric transducer and an amplitude transformer. The piezoelectric transducer is adapted to convert electrical signals into mechanical vibrations, and the amplitude transformer is adapted to increase the amplitude of the mechanical vibrations.

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