Device and method for machining microstructure on surface of curved-surface thin-wall part

Abstract

In order to solve the technical problem that an anti-drag microstructure cannot be machined on the surface of a curved-surface thin-wall part made of a high-hardness material through an existing rolling forming method and equipment, the invention provides a device and method for machining the microstructure on the surface of the curved-surface thin-wall part. The device comprises a numerical control machine tool, an ultrasonic vibration unit and a micro-structure rolling unit, the micro-structure rolling unit comprises a roller with a whole circle of micro-structure protrusions, and under the combined action of the numerical control machine tool and the ultrasonic vibration unit, the whole circle of the micro-structure protrusions can be rolled. The area, needing to be machined with the microstructure, of the surface of the curved-surface thin-wall part is extruded to generate uniform plastic flow, so that the microstructure matched with the microstructure protrusion on the roller in shape and size is formed, microstructure machining of the surface of the metal curved-surface thin-wall part difficult to machine is achieved, and the beneficial effects of being easy to operate and high in precision are achieved.

Description

Technical Field

[0001] The invention relates to a device and a method for processing microstructure on the surface of a curved thin-walled part. Background Art

[0002] The processing of surface functional microstructures is a new topic in the field of manufacturing and processing in recent years. Processing different microstructures on the surface of parts can give the parts different superior properties, such as anti-fog function, anti-icing function, corrosion resistance, drag reduction and anti-fouling performance. Among them, microstructures used for drag reduction have become one of the focuses in the field of aerospace manufacturing.

[0003] At present, the preparation methods of surface functional microstructures can be mainly divided into surface material removal method and plastic forming method. Surface material removal method includes special processing (high precision), ultra-precision machining (high efficiency) and etching method (good structural uniformity, simple device), etc. These methods have the disadvantages of high cost, long time consumption and difficulty in preparing microstructures on a large scale, and cannot meet the requirements of continuous production and processing of microstructures. Plastic forming method includes surface imprinting method, bionic replication method and rolling forming method. Among them, surface imprinting method and bionic replication method have certain limitations, such as small forming area, low forming efficiency, large required forming force and other shortcomings, which are not conducive to large-area continuous preparation of microstructures.

[0004] Relatively speaking, the roll forming method is an effective method for processing surface functional microstructures, which has the advantages of low production cost and high efficiency. The roll forming method is mainly divided into two processes, one is the roll-to-roll forming process, and the other is the roll-to-flat plate forming process. The processing objects of these roll forming processes are mainly flat materials with low hardness and good plastic formability, such as flat aluminum plates and flat copper plates. With the development of aerospace technology, the demand for surface drag reduction microstructures of curved thin-walled parts made of high-hardness materials is increasing, and the two existing roll forming processes can no longer meet this demand. Summary of the invention

[0005] In order to solve the technical problem that the existing rolling forming methods and equipment are unable to process drag reducing microstructures on the surface of curved thin-walled parts made of high hardness materials, the present invention proposes a device and method for processing microstructures on the surface of curved thin-walled parts.

[0006] The technical solution of the present invention is:

[0007] A device for processing microstructures on the surface of a curved thin-walled part, which is special in that it includes a numerically controlled machine tool, an ultrasonic vibration unit and a microstructure rolling unit;

[0008] The microstructure rolling unit is connected to the machine tool spindle in the CNC machine tool through the ultrasonic vibration unit, and moves on the surface of the curved thin-walled part to be processed according to a set trajectory under the drive of the machine tool spindle;

[0009] The ultrasonic vibration unit is used to generate a mechanical vibration signal and transmit it to the microstructure rolling unit, so that it presses down the surface of the curved thin-walled part to be processed to cause plastic flow;

[0010] The microstructure rolling unit comprises a first bracket, a roller and a second bracket which are arranged in sequence; the first bracket and the second bracket are both provided with bearing mounting holes; the roller comprises a roller and support shafts on both sides of the roller, and the support shafts are mounted in the bearing mounting holes of the first bracket and the second bracket through bearings;

[0011] The roller is a wheel-type symmetrical structure, and the diameter gradually decreases from the middle to both sides; a full circle of microstructure protrusions is centrally arranged on the largest outer circumferential surface in the middle of the roller, and the edges of the microstructure protrusions are chamfered.

[0012] Preferably, two microstructure protrusions with a certain distance between them are centrally arranged on the largest outer circumferential surface in the middle of the roller, and the cross-sectional shape and size of the two microstructure protrusions are the same; the pits formed by the two microstructure protrusions are chamfered.

[0013] Preferably, the angle between two microstructure protrusions is 30-60°, and the fillet radius is 0.005-0.007 mm.

[0014] Preferably, the radial height of a single microstructure protrusion is equal to 1 / 2 of the distance between two microstructure protrusions.

[0015] Preferably, the radius of the rounded corners at the edges of the microstructure protrusions is 0.007-0.012 mm.

[0016] Preferably, the cross-sectional shape of the microstructure protrusion is trapezoidal, triangular or rectangular.

[0017] Preferably, the roller and its two side brackets are manufactured by integrated precision grinding with a molding error within 10 μm, and the material is cemented carbide; the first bracket and the second bracket are both made of high-strength titanium alloy.

[0018] The present invention also provides a method for machining microstructures on the surface of a curved thin-walled part based on the above-mentioned device for machining microstructures on the surface of a curved thin-walled part, the special features of which are:

[0019] Step 1: Clamp the curved thin-walled part to be processed on the workbench of the CNC machine tool;

[0020] Step 2: Connect the ultrasonic transducers in the microstructure rolling unit and the ultrasonic vibration unit to the machine spindle of the CNC machine tool, turn on the ultrasonic transmitter in the ultrasonic vibration unit, and set different ultrasonic frequencies and amplitudes;

[0021] Step 3: Set different pressing depths and feed speeds in the Z direction, and according to the curved surface forming tool path pre-generated by the line projection method, make the roller in the microstructure rolling unit displace in the Y-axis direction to control the length and depth of the formed microstructure. During the processing, turn on the cooling and lubrication system of the CNC machine tool and keep its universal tube aligned with the contact area between the curved thin-walled part to be processed and the roller until the rolling is completed;

[0022] Step 4: The roller slowly moves upward in the Z direction to separate from the curved thin-walled part to be processed, and the surface of the curved thin-walled part to be processed is formed into a microstructure required by the design.

[0023] The beneficial effects of the present invention are:

[0024] 1. The microstructure rolling unit in the present invention includes a roller with a full circle of microstructure protrusions. Under the combined action of the CNC machine tool and the ultrasonic vibration unit in the present invention, the roller is extruded in the area on the surface of the curved thin-walled part where the microstructure needs to be processed to produce uniform plastic flow, thereby forming a microstructure that matches the shape and size of the microstructure protrusions on the roller, thereby realizing microstructure processing on the surface of difficult-to-process metal curved thin-walled parts, and has the advantages of simple operation and high precision.

[0025] 2. Compared with the traditional method that can only manufacture microstructures on a plane, the device of the present invention does not require a complex control system. It can roll and manufacture various microstructures that improve surface properties on free-form surface metal parts by relying on the line projection path planning of the CNC machine tool.

[0026] 3. For the requirements of surface functional microstructures of different sizes and shapes, the present invention only needs to design and replace the rollers in the microstructure rolling unit according to the shape and size of the microstructure to meet the processing requirements.

[0027] 4. The present invention adopts a cooling, lubricating and ultrasonically assisted rolling method, which is beneficial to reducing the wear of the roller.

[0028] 5. The roller in the present invention is made of WC hard alloy, which has high hardness and is not easy to deform, and can roll difficult-to-process high-hardness materials, such as titanium alloy, nickel alloy and other materials.

[0029] 6. The present invention can process workpieces of different thicknesses by adjusting the roller position, pressure and feed speed, and has a wide range of applications.

[0030] 7. The surface microstructure size obtained by roll forming by the present invention can reach 30μm level (such as Fig.10 The surface residual compressive stress value is improved to above 400MPa (as shown in Fig.11 As shown in the figure), the workpiece surface is provided with a complete and defect-free microstructure without any deformation of the workpiece.

[0031] 8. The roller obtained by integrated precision grinding in the present invention will not deviate during rolling processing, and the processing error is small, which is suitable for surface microstructure molding with micron-level requirements.

[0032] 9. The bracket made of titanium alloy in the present invention ensures the low-friction rotation of the roller. The overall size of the roller can be 93mm in length and 23mm in width. The smaller size reduces the tool interference in the forming processing of some thin-walled parts with large torsion such as blades. For long-term service, only the bearings and rollers need to be replaced. The simple device and easy installation and control can ensure the non-interference vertical downward contact between the roller and the workpiece, which greatly improves the accuracy and processing efficiency in micro-structure processing.

[0033] 10. In the present invention, the curved surface rolling tool path is generated by the line projection method, and the tool contact point trajectory is offset onto the curved surface along the normal direction of the curved surface. Then, the shortest distance from the tool position point to the curved surface is used for interference detection and adjustment to ensure that the roller is in exact contact with the curved surface during rolling, thereby reducing contact errors and improving forming accuracy.

[0034] 11. The tools commonly used in existing microstructure rolling are rolling balls or long rollers with microstructure protrusions. Rolling balls have good adaptability and can be used to strengthen curved surfaces, but the shape of the surface formed by the rolling ball is uncontrollable; the shape of the long roller with microstructure protrusions is controllable, but the processing conditions are suitable for flat rolling, and the length of the front rolling roller is too long. The present invention uses a roller with microstructure protrusions, which is not only suitable for curved surface processing, but also has high forming accuracy and good controllability.

[0035] 12. In the present invention, two microstructure protrusions with a certain distance are centrally arranged on the largest outer circumference of the roller, and the cross-sectional shape and size of the two microstructure protrusions are the same, thereby ensuring the controllability and consistency of the formed microstructure and high forming efficiency.

[0036] 13. In the present invention, the pits formed by the two microstructure protrusions on the roller are chamfered with a radius of 0.005mm-0.007mm, which can reduce stress concentration on the one hand, and avoid unilateral deformation of the microstructure protrusion (single side of the raceway) on the other hand, thereby delaying the wear of the microstructure protrusion on the roller.

[0037] 14. In the present invention, the angle between the two microstructure protrusions on the roller is 30-60°, which is beneficial to the deformation flow of the material during the processing and is conducive to improving the microstructure molding quality; the radial height (rib height) of a single microstructure protrusion is equal to 1 / 2 of the spacing (rib spacing) between the two microstructure protrusions, and the aerodynamic drag reduction performance is optimal. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the three-dimensional structure of the device of the present invention.

[0039] Figure 2 It is a schematic structural diagram of the microstructure rolling unit in the present invention.

[0040] Figure 3 for Figure 2 Exploded diagram.

[0041] Figure 4 This is a structural diagram of the roller in the microstructure rolling unit.

[0042] Figure 5 This is an enlarged view of the microstructure protrusions with different cross-sectional shapes on the roller.

[0043] Figure 6 It is a schematic diagram of the structure of the first bracket in the microstructure rolling unit.

[0044] Figure 7 It is a schematic diagram of the structure of the ultrasonic vibration unit in the present invention.

[0045] Figure 8 Schematic diagram of the projection trajectory of the surface processing line.

[0046] Fig. 9 Based on Figure 8 The three-dimensional morphology of the microstructure obtained by the curved rolling trajectory shown.

[0047] Fig.10 for Fig. 9 Cross-sectional measurement dimensions of mesostructures.

[0048] Fig.11 Surface residual stress test results.

[0049] Description of reference numerals:

[0050] 1-CNC machine tool; 11-workbench; 12-universal tube; 13-machine tool spindle;

[0051] 2-ultrasonic vibration unit; 21-ultrasonic transmitter; 22-energy transmission head connecting rod; 23-ultrasonic transducer; 24-holding ring;

[0052] 3-microstructure rolling unit; 31-first bracket; 311-bolt through hole; 312-positioning pin hole; 313-bearing mounting hole; 32-roller; 321-roller; 3211-microstructure protrusion; 322-support shaft; 33-second bracket; 331-connecting rod; 34-bolt; 35-nut; 36-bearing; 37-positioning pin; 38-gasket;

[0053] 4-Workpiece;

[0054] 6-Clamp;

[0055] 7-Force platform. DETAILED DESCRIPTION

[0056] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0057] like Figure 1-7 As shown, the device for machining microstructure on the surface of a curved thin-walled part provided by the present invention comprises a numerically controlled machine tool 1, an ultrasonic vibration unit 2 and a microstructure rolling unit 3.

[0058] The CNC machine tool 1 is an existing device, which mainly includes a bed, a machine tool spindle 13, a workbench 11, a CNC system, a drive system, a transmission system and a cooling and lubrication system, wherein the workbench 11 is used to place the workpiece 4 to be processed; the machine tool spindle is used to move some parts and components in the ultrasonic vibration unit 2 and the microstructure rolling unit 3; the universal tube 12 used to transport the coolant in the cooling and lubrication system is always aligned with the contact area between the workpiece 4 and the microstructure rolling unit 3 to cool and lubricate the contact area. On this basis, a dynamometer for detecting the contact state between the workpiece 4 to be processed and the microstructure rolling unit 3 can also be set on the workbench 11; before the downward pressure starts, the force in the Z direction is controlled to 0N with the help of the dynamometer, which can ensure that the initial contact state between the workpiece and the microstructure rolling unit 3 is just in contact, thereby ensuring the rolling accuracy.

[0059] like Figure 7 As shown, the ultrasonic vibration unit 2 is used to generate a mechanical vibration signal and transmit it to the microstructure rolling unit 3. The ultrasonic vibration unit 2 includes an ultrasonic transmitter 21, an energy transmission head connecting rod 22, an ultrasonic transducer 23 and a ring 24, and the ring 24, the energy transmission head connecting rod 22 and the ultrasonic transducer 23 are arranged in sequence from top to bottom. The ultrasonic transmitter 21 is used to generate a high-frequency electrical signal with a set frequency and amplitude (the frequency can be adjusted between 18Khz-27Khz, and the amplitude can be adjusted between 1.5-5μm), and then the high-frequency electrical signal is transmitted to the ultrasonic transducer 23 through the energy transmission head connecting rod 22, and the ultrasonic transducer 23 converts the high-frequency electrical signal into a mechanical vibration signal and transmits it to the microstructure rolling unit 3, so that the microstructure rolling unit 3 vibrates; the ring 24 is used to connect the energy transmission head connecting rod 22 to the machine tool spindle 13.

[0060] The microstructure rolling unit 3 is used to squeeze the surface of the workpiece 4 in the area where the microstructure needs to be processed on the surface of the workpiece 4 to cause plastic flow, thereby forming the desired microstructure on the surface of the workpiece 4. Figure 2-6As shown, the microstructure rolling unit 3 includes a first bracket 31, a roller 32 and a second bracket 33 which are arranged in sequence; the first bracket 31 and the second bracket 33 are both provided with a bolt 34 through hole 311, a positioning pin 37 hole 312 and a bearing mounting hole 313; the first bracket 31 and the second bracket 33 are positioned by installing a positioning pin 37 at the positioning pin 37 hole 312, and are connected by installing a bolt 34 nut 35 assembly at the bolt 34 through hole 311; the roller 32 includes a roller 321 and support shafts 322 on both sides of the roller 321; the support shafts 322 on both sides of the roller 32 are installed in the bearing mounting holes 313 of the first bracket 31 and the second bracket 33 through bearings 36, so that the roller 32 is installed between the first bracket 31 and the second bracket 33. The present invention utilizes the positioning pin 37 to position the first bracket 31 and the second bracket 33. This is because it is difficult to limit the freedom of the first bracket 31 and the second bracket 33 during processing by simply connecting the bolt 34 and nut 35 components, which can easily cause an offset between the first bracket 31 and the second bracket 33 and affect the processing and forming structure.

[0061] like Figure 3 As shown, in order to realize the connection between the microstructure rolling unit 3 and the ultrasonic vibration unit 2 and the CNC machine tool 1, a connecting rod 331 is provided at the upper end of the second bracket 33, and the connecting rod 331 is used to connect the microstructure rolling unit 3 as a whole with the ultrasonic transducer 23 in the ultrasonic vibration unit 2, and can be connected to the ultrasonic transducer 23 through a spring clamp, so as to receive the mechanical vibration signal output by the ultrasonic transducer 23. In addition, in order to reduce the weight of the bracket and ensure that the bracket is not easily deformed, the first bracket 31 and the second bracket 33 are preferably made of high-strength titanium alloy.

[0062] like Figure 4-5 As shown, the roller 321 in the roller 32 is a wheel-type symmetrical structure, and the diameter gradually decreases from the middle to both sides; on the largest outer circumferential surface in the middle of the roller 321, a full circle of microstructure protrusions 3211 is centrally arranged, and the cross-section of the microstructure protrusion 3211 is trapezoidal, triangular or rectangular, and the edges of the microstructure protrusion 3211 are chamfered to reduce stress concentration. Considering that the processing is difficult when the fillet is too small, and the effect of alleviating stress concentration is poor when the fillet is too large, the fillet radius range is preferably 0.007mm-0.012mm.

[0063] Considering that the forming efficiency of the microstructure protrusion 3211 of a single pass is low, and the microstructure morphology obtained after rolling of the microstructure protrusion 3211 of three passes or more will be destroyed by the plastic flow of the materials on both sides, making the final forming effect worse, the present invention preferably adopts two passes of microstructure protrusion 3211 with a certain spacing centered on the maximum outer circumference of the roller 321, that is, two full circles of microstructure protrusion 3211 are set, and the cross-sectional shape and size of the microstructure protrusion 3211 of the two passes are the same; the cross-sectional shape of the microstructure protrusion 3211 of the two passes is The shape and size are the same, which can ensure the controllability and consistency of the formed microstructure; similarly, in order to reduce stress concentration, the pits formed by the two microstructure protrusions 3211 also need to be rounded. Considering that the pits are the intersection of the two material flows, if the fillet is too large, the stress concentration of rolling will be more obvious, which is easy to cause the microstructure protrusion to deform on one side (one side of the raceway) and aggravate the wear of the microstructure protrusion on the roller. Therefore, the fillet radius of the pits formed by the two microstructure protrusions 3211 is preferably in the range of 0.005mm-0.007mm. When the angle between the two microstructure protrusions 3211 is 30-60°, it is beneficial to the deformation flow of the material during the processing process and is conducive to improving the quality of microstructure forming; when the radial height (rib height) of a single microstructure protrusion 3211 is equal to 1 / 2 of the spacing (rib spacing) between the two microstructure protrusions 3211, the aerodynamic drag reduction performance is optimal.

[0064] At the same time, the shape and size of the roller 321 in the roller 32 should also be adapted to the shape and size of the surface of the curved thin-walled part to be processed, and the cross-sectional shape, axial width, and radial height of the single-circle microstructure protrusion 3211 on the roller 321 should be adapted to the shape and size of the microstructure required to be formed on the surface of the workpiece 4 to be processed, thereby effectively controlling the microstructure forming shape of the roller 321 during the rolling process of the curved thin-walled part, and improving the surface performance of the curved thin-walled part. In addition, in order to ensure and improve the strength of the roller 32, the roller 32 is made of a cemented carbide material as a whole, such as WC-Co cemented carbide.

[0065] In order to further improve the processing accuracy, in addition to the roller 321 with micro-structure protrusions, the brackets on both sides of the roller 321 are also high-precision ground together with the roller 321. The part molding error is within 10μm and the overall dimensional accuracy is high.

[0066] During processing, the workpiece 4 to be processed is set on the worktable 11 of the CNC machine tool 1. The microstructure rolling unit 3, driven by the machine tool spindle, moves on the surface of the workpiece 4 according to the pre-set curved tool path trajectory. The roller 32 in the microstructure rolling unit 3 contacts the surface of the workpiece 4, and under the action of the mechanical vibration signal transmitted to the roller 32 by the ultrasonic vibration unit 2, the surface of the workpiece 4 is squeezed to make it plastic flow, thereby forming a microstructure on the surface of the workpiece 4 that matches the shape and size of the microstructure protrusion 3211 on the maximum circumferential surface of the middle part of the roller 32. Among them, the pre-set curved tool path trajectory can be generated by UG based on the line projection method. First, the tool position point trajectory (the moving trajectory of the roller) is planned, and then the tool position point trajectory is offset to the curved surface along the normal direction of the surface of the workpiece to be processed, and then the shortest distance from the tool position point to the curved surface is used to perform interference detection and adjustment, and finally generate a curved tool path trajectory without interference.

[0067] In this embodiment:

[0068] The total axial length of the roller 32 in the microstructure rolling unit 3 is 23 mm, the thickness of the roller 321 is 5 mm, the maximum outer diameter of the roller 321 is 20 mm, the axial width of the circumferential surface where the microstructure protrusion 3211 is located is 1 mm, the diameter of the support shaft 322 on both sides of the roller 321 is 5 mm, the spacing between the two passes of the microstructure protrusion 3211 is 0.07 mm, the radius of the fillet at the edge of the single-pass microstructure protrusion 3211 is 0.007 mm, and the chamfer of the pit between the two passes is 0.005 mm.

[0069] The microstructure protrusions 3211 have two layers, and the cross-sectional shape can be trapezoidal, triangular or rectangular; the angles and sizes corresponding to the microstructure protrusions 3211 with different cross-sectional shapes are shown in Table 1 below.

[0070] Table 1 Angles and sizes of different microstructure protrusions 3211

[0071]

[0072] Processing effect verification:

[0073] The metal curved surface piece to be processed is placed horizontally and fixed on the workbench 11 of the CNC machine tool 1 by a clamp, and the metal curved surface piece is located below the roller 32 in the microstructure rolling unit 3; the CNC system of the CNC machine tool 1 is introduced Fig. 9 The curved surface rolling trajectory obtained by the line projection method is shown, the feed speed and the pressing depth are set, the ultrasonic vibration unit 2 is debugged, the frequency and amplitude are set, and the cooling and lubrication system of the CNC machine tool 1 is turned on. The roller 32 rolls along the metal curved surface part driven by the machine tool spindle of the CNC machine tool 1. The upper surface of the metal curved surface part contacts the microstructure protrusion 3211 of the roller 32 and is squeezed by the microstructure protrusion 3211. After the rolling process is completed, a microstructure with a trapezoidal cross section is obtained on the surface of the metal curved surface part. Fig. 9 This is the overall morphology of the obtained microstructure. It can be seen that the raceway is smooth and has no defects. Fig.10 for Fig. 9 The cross-sectional measurement dimensions of the microstructure are Fig.10 It can be seen that the depth of the trapezoidal microstructure is 32 μm and the width is 72 μm (close to the design requirements), and the rolling forming effect on both sides of the raceway is good. Fig.11 It can be seen that after machining a trapezoidal microstructure on the surface of a metal curved surface part using the device and method of the present invention, the value of the surface residual compressive stress can be improved to above 400 MPa.

[0074] The method for machining microstructure on the surface of a curved thin-walled part by using the device of the present invention is as follows:

[0075] Step 1: Clamp and fix the curved workpiece 4 on the workbench 11;

[0076] Step 2: Connect the microstructure rolling unit 3 and the ultrasonic transducer 23 to the machine tool spindle 13, turn on the ultrasonic transmitter 21, and set different ultrasonic frequencies and amplitudes;

[0077] Step 3: Set different pressing depths and feed speeds in the Z direction, and according to the curved tool path pre-generated by the line projection method, displace the roller 32 in the microstructure rolling unit 3 in the Y-axis direction to control the length and depth of the formed microstructure. During the processing, turn on the cooling and lubrication system of the CNC machine tool 1 and keep the universal tube aligned with the contact area between the workpiece 4 and the roller 32 until the rolling is completed;

[0078] Step 4: After the rolling is completed, the roller 32 slowly moves in the Z direction to separate from the workpiece 4, and the microstructure required by the design is formed on the surface of the workpiece 4.

Claims

1. A device for processing microstructures on the surface of a curved thin-walled part, characterized in that: It includes a CNC machine tool, an ultrasonic vibration unit and a microstructure rolling unit; The microstructure rolling unit is connected to the machine tool spindle in the CNC machine tool through the ultrasonic vibration unit, and moves on the surface of the curved thin-walled part to be processed according to a set trajectory under the drive of the machine tool spindle; The ultrasonic vibration unit is used to generate a mechanical vibration signal and transmit it to the microstructure rolling unit, so that it presses down the surface of the curved thin-walled part to be processed to cause plastic flow; The microstructure rolling unit comprises a first bracket, a roller and a second bracket which are arranged in sequence; the first bracket and the second bracket are both provided with bearing mounting holes; the roller comprises a roller and support shafts on both sides of the roller, and the support shafts are mounted in the bearing mounting holes of the first bracket and the second bracket through bearings; The roller is a wheel-type symmetrical structure, and the diameter gradually decreases from the middle to both sides; a full circle of microstructure protrusions is centrally arranged on the largest outer circumferential surface in the middle of the roller, and the edges of the microstructure protrusions are chamfered.

2. The device for machining microstructures on the surface of a curved thin-walled part according to claim 1, characterized in that: On the largest outer circumferential surface in the middle of the roller, two microstructure protrusions with a certain distance are centrally arranged, and the cross-sectional shape and size of the two microstructure protrusions are the same; the pits formed by the two microstructure protrusions are chamfered.

3. The device for machining microstructures on the surface of a curved thin-walled part according to claim 2, characterized in that: The angle between two microstructure protrusions is 30-60°, and the fillet radius is 0.005-0.007 mm.

4. The device for machining microstructures on the surface of a curved thin-walled part according to claim 2, characterized in that: The radial height of a single microstructure protrusion is equal to 1 / 2 of the distance between two microstructure protrusions.

5. The device for processing microstructure on the surface of a curved thin-walled part according to any one of claims 1 to 4, characterized in that: The radius of the rounded corners at the edges of the microstructure protrusions is 0.007-0.012 mm.

6. The device for machining microstructures on the surface of a curved thin-walled part according to claim 5, characterized in that: The cross-sectional shape of the microstructure protrusion is trapezoidal, triangular or rectangular.

7. The device for machining microstructures on the surface of a curved thin-walled part according to claim 5, characterized in that: The roller and the brackets on both sides thereof are made by integrated precision grinding with a molding error within 10 μm, and the material is cemented carbide; the first bracket and the second bracket are both made of high-strength titanium alloy.

8. A method for machining microstructures on the surface of a curved thin-walled part based on the device for machining microstructures on the surface of a curved thin-walled part according to any one of claims 1 to 7, characterized in that: Includes steps: Step 1: Clamp the curved thin-walled part to be processed on the workbench of the CNC machine tool; Step 2: Connect the ultrasonic transducers in the microstructure rolling unit and the ultrasonic vibration unit to the machine spindle of the CNC machine tool, turn on the ultrasonic transmitter in the ultrasonic vibration unit, and set different ultrasonic frequencies and amplitudes; Step 3: Set different pressing depths and feed speeds in the Z direction, and according to the curved surface forming tool path pre-generated by the line projection method, make the roller in the microstructure rolling unit displace in the Y-axis direction to control the length and depth of the formed microstructure. During the processing, turn on the cooling and lubrication system of the CNC machine tool and keep its universal tube aligned with the contact area between the curved thin-walled part to be processed and the roller until the rolling is completed; Step 4: The roller slowly moves upward in the Z direction to separate from the curved thin-walled part to be processed, and the surface of the curved thin-walled part to be processed is formed into a microstructure required by the design.

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