Five-axis linkage dot-scraping forming method for metal surface microstructures under complex working conditions

Abstract

To address the technical challenges of existing surface microstructure processing methods in simultaneously achieving high precision, high surface quality, high efficiency, strong adaptability, high controllability, and low cost, this invention proposes a five-axis linkage dot-matrix forming method for metal surface microstructures under complex working conditions. This invention utilizes the small size and high replaceability of micro-needle tools, combined with the high precision and high degree of freedom of five-axis linkage CNC machine tools. For different complex working conditions, the micro-needle tool's position and posture can be continuously and precisely adjusted using a five-axis linkage CNC machine tool. This allows for the processing of required array microstructures on the surface of metal workpieces with limited operating space, free-form surfaces, and thin-walled, easily deformable surfaces. This overcomes the shortcomings of traditional mold imprinting technology, such as low controllability of microstructure distribution, and the damage to material surface integrity caused by micro-milling. It improves the forming efficiency of microstructures and offers the advantages of high precision, high surface quality, and low cost.

Description

Technical Field

[0001] This invention relates to the field of metal surface microstructure processing technology, and more specifically to a method for forming metal surface microstructures under complex working conditions. Background Technology

[0002] Extensive engineering practice and biomimetic research have shown that surface microstructures can endow parts with special surface properties. Common groove or pit microstructures have been extensively studied for their effects on drag reduction, sealing, and lubrication. The morphology optimization and arrangement of microstructures have a positive impact on the surface properties of parts, and they have good application prospects in the fields of electromechanical engineering, aerospace, and biomedicine. Although the sizes of biomimetic microstructures of different shapes are different, they are all at the micrometer level. Therefore, the processing of microstructures has certain requirements on the size, precision, and degree of freedom of the forming equipment, making it difficult to combine high precision, high surface quality, and high efficiency.

[0003] To date, the main methods for fabricating surface microstructures have relied on electrical discharge machining (EDM), ion beam etching, laser processing, micro-milling, grinding, and microimprinting. While EDM, ion beam etching, and laser processing offer high efficiency, the resulting surface ablation and oxidation, as well as low processing precision, cannot be ignored. Furthermore, most of these methods involve expensive equipment and demanding processing requirements. Micro-milling and grinding, being subtractive manufacturing processes, can fully leverage the high efficiency of multi-axis CNC machining. However, the resulting microstructure edges inevitably contain burrs, scratches, and other defects, compromising the surface integrity of the microstructure and making it difficult to guarantee the stability of the workpiece surface, especially the microstructure quality. Microimprinting produces high-quality microstructures, but its manufacturing cost is high, and the shape of the microstructure is limited by the imprinting mold, resulting in limited controllability of its distribution.

[0004] Therefore, there is an urgent need to develop a metal surface microstructure processing technology that is high-precision, low-cost, efficient, and highly adaptable. Summary of the Invention

[0005] To address the technical challenges of existing surface microstructure processing methods in simultaneously achieving high precision, high surface quality, high efficiency, strong adaptability, high controllability, and low cost, this invention proposes a five-axis linkage dot-and-scribe forming method for metal surface microstructures under complex working conditions.

[0006] The technical solution of this invention is:

[0007] A five-axis linkage dot-and-scratch forming method for metal surface microstructures under complex working conditions is characterized by the following steps:

[0008] Step 1: Preparation before processing;

[0009] Step 1.1 Engineering model design and modeling;

[0010] Design and manufacture microneedle tools, construct CAD models of microneedle tools and import them into CAM software; create a tool library in the CAM software and put the CAD models of the microneedle tools into the tool library after numbering them sequentially;

[0011] Construct CAD models and microstructure CAD models of the workpiece to be processed and import them into CAM software;

[0012] Step 1.2: Compile machining project templates for different microstructures under normal and complex working conditions and import them into a five-axis CNC machine tool;

[0013] Step 1.2.1 involves matching the CAD model of the microstructure constructed in Step 1.1 with the applicable processing method, and compiling processing project templates for various types of microstructures under normal working conditions:

[0014] If the microstructure is a pit microstructure, the point pressing method is used for processing. In the CAM software, the micro needle tool processing trajectory is generated based on the CAD model of the micro needle tool, the workpiece to be processed and the microstructure constructed in step 1.1, and the point pressing processing toolpath program with adjustable parameters is compiled, named and saved as the point pressing processing project template corresponding to the pit microstructure under normal working conditions.

[0015] If the microstructure is a microgroove structure, it is processed by scribing. In the CAM software, the micro-needle tool processing trajectory is generated based on the CAD model of the micro-needle tool, the workpiece to be processed and the microstructure constructed in step 1.1. A scribing processing toolpath program with adjustable parameters is compiled, named and saved as the scribing processing project template corresponding to the microgroove structure under normal working conditions.

[0016] If the microstructure is a biomimetic "ridge-like" microstructure, then the overlapping point pressing and / or scribing processing method is adopted in the processing area, and the processing project template corresponding to the pit microstructure and / or microgroove structure under conventional working conditions is directly called.

[0017] Step 1.2.2: Compile processing project templates for various types of microstructures under complex working conditions:

[0018] If the microstructure to be machined places the microneedle tool in a narrow and confined space, then a dot-and-dash machining with regional variable tool axis angle is adopted. In the machining project templates corresponding to each type of microstructure under the normal working conditions obtained in step 1.2.1, a modification program segment related to the size of the machining space and used to adjust the tool axis angle parameters is added to obtain the machining project templates for each type of microstructure under the working conditions of limited machining space.

[0019] If the microstructure to be machined is on a free surface, a dot-mapping machining method is adopted to keep the direction of the micro-needle tool axis consistent with the normal vector of the cutting contact point. In the machining project templates corresponding to each type of microstructure under normal working conditions obtained in step 1.2.1, a modification program segment related to the curvature of the workpiece surface and used to adjust the projection vector and tool axis angle parameters is added to obtain the machining project templates corresponding to each type of microstructure on the free surface.

[0020] If the microstructure to be processed is on a thin-walled, easily deformable workpiece, then the microstructure is processed in a progressive dot-mapping manner by layering it along the depth. In the processing project templates corresponding to each type of microstructure under the normal working conditions obtained in step 1.2.1, a modification program segment related to the workpiece wall thickness is added to adjust the cutting depth and step distance parameters, so as to obtain the processing project templates corresponding to each type of microstructure on the thin-walled, easily deformable workpiece.

[0021] Step 1.2.3 After converting the machining project templates corresponding to various types of microstructures under normal and complex working conditions obtained in Steps 1.2.1 and 1.2.2 into file types that can be recognized by the five-axis CNC machine tool, import them into the five-axis CNC machine tool.

[0022] Step 1.3 Select processing parameters;

[0023] Select processing parameters, including the feed rate of the microneedle tool, the depth of indentation, the ultrasonic amplitude, and the ultrasonic vibration frequency;

[0024] Step 2: Fabricate microstructures on the test specimen;

[0025] Based on the machining project template of the five-axis CNC machine tool imported in step 1.2.3, the tool library formulated in step 1.1, and the machining parameters selected in step 1.3, micro needle tools are installed on the five-axis CNC machine tool. After being installed and adjusted in place, the microstructure is machined on the test piece using the five-axis CNC machine tool.

[0026] Step 3: Microstructure forming inspection to determine microstructure processing parameters;

[0027] The forming quality of the microstructures processed on the test piece is inspected to determine the microstructure processing parameters that meet the requirements of dimensional accuracy, surface roughness and hardness.

[0028] Step 4: Machining microstructures on the workpiece;

[0029] Based on the microstructure processing parameters determined in step 3, the required microstructure is processed on the workpiece using a five-axis CNC machine tool using the same method as in step 2.

[0030] Furthermore, in step 1, the corresponding microneedle tool structure and size are designed according to the shape, size, and processing space of the different microstructures to be processed.

[0031] Furthermore, in step 1.3, the feed rate and depth of the microneedle tool are selected based on the material, thickness, processing space, microneedle tool life, workpiece deformation error, and processing efficiency of the workpiece to be processed; and the ultrasonic amplitude and ultrasonic vibration frequency are selected based on the surface quality requirements of the microstructure and the strength of the workpiece to be processed.

[0032] Furthermore, if the depth of the microstructure to be processed is 10-999 micrometers, the feed speed of the microneedle tool is 2-40 mm / min, the pressing depth is 0-200 μm, the ultrasonic amplitude is 1.5-5 μm, and the ultrasonic vibration frequency is 20-40 kHz.

[0033] Furthermore, step 2 specifically involves:

[0034] Step 2.1 Test piece installation: Fix the test piece on the worktable of the five-axis CNC machine tool, and use the contact probe to align the test piece as required;

[0035] Step 2.2 Microneedle Tool Installation: Adjust and install the microneedle tools in sequence according to the CAD model numbers of the microneedle tools in the tool library specified in Step 1. These microneedle tools include microneedle tools with different overhang lengths required in the transverse and longitudinal ultrasonic vibration directions, as well as microneedle tools with effective cutting edges of different shapes and sizes. Use the automatic tool setting system of the five-axis machine tool to set each microneedle tool and place them in the tool library of the five-axis CNC machine tool in sequence.

[0036] Step 2.3 Program Execution: Select a matching microneedle tool from the tool library according to the shape and size of the microstructure to be processed. For point-press forming pit microstructures, select a microneedle tool with the required overhang length for longitudinal vibration. For scribing forming groove microstructures, select a microneedle tool with the required overhang length for transverse vibration. Call and execute the appropriate processing project template according to the microstructure type and working conditions. Perform five-axis linkage point-scribing processing on the test piece. During the processing, the five-axis CNC machine tool judges in real time whether the microneedle tool is worn or broken based on the stability of the force signal collected by the force measuring table, so as to replace the tool in time.

[0037] Further, step 3 specifically involves: using an automatic zoom three-dimensional surface measuring instrument to measure the cross-sectional dimensions and surface roughness of the microstructure processed on the test piece; then using a hardness tester to test the surface hardness of the microstructure that meets the requirements for dimensional accuracy and surface roughness; and finally determining the microstructure processing parameters that meet the requirements for dimensional accuracy, surface roughness, and hardness.

[0038] The present invention also provides a five-axis linkage dot-and-dash forming device for complex working conditions of metal surface microstructures to realize the above-mentioned five-axis linkage dot-and-dash forming method. Its special feature is that it includes a five-axis CNC machine tool, an ultrasonic energy generator, a central water outlet ultrasonic tool holder, an ultrasonic energy transmission ring, and a micro needle tool.

[0039] The ultrasonic energy generator is connected to the ultrasonic energy transfer ring, which is fixed on the headstock of a five-axis CNC machine tool. The lower end of the spindle of the five-axis CNC machine tool is connected to the central water-emitting ultrasonic tool holder, which is connected to the micro-needle tool. The micro-needle tool directly acts on the workpiece to be processed. The ultrasonic energy transfer ring and the central water-emitting ultrasonic tool holder are not in direct contact and the gap is less than or equal to 1 mm. The electromagnetic output ring on the ultrasonic energy transfer ring is aligned vertically with the receiving ring of the central water-emitting ultrasonic tool holder.

[0040] Microneedle cutters consist of a straight shank and a tapered cutting edge; the effective cutting edge shape and size of the tapered cutting edge are matched with the shape and size of the microstructure to be machined.

[0041] The beneficial effects of this invention are:

[0042] 1. The forming method of the present invention is based on five-axis linkage machining, which more closely integrates process parameters with actual working conditions. By changing different machining parameters and planning different paths, it is possible to use a micro-needle tool (here, a micro-needle tool refers to a batch of tools with the same effective blade shape and size, but different overhang lengths, which can be switched with the tool magazine and automatic tool changer of the five-axis CNC machine tool) to form micron-level pits, grooves and biomimetic "ridge" microstructures through point pressure and / or scribing, which reduces manufacturing costs and is not limited to machining on conventional workpieces such as flat plates and rotating bodies.

[0043] 2. This invention utilizes the small size and high replaceability of microneedle cutters, combined with the high precision and high degree of freedom of five-axis CNC machine tools. For various complex working conditions, the position and posture of the microneedle cutters can be continuously and precisely adjusted using a five-axis CNC machine tool. This allows for the fabrication of desired array microstructures on the surface of metal workpieces with limited operating space, free-form surfaces, or thin-walled, easily deformable surfaces. This invention overcomes the shortcomings of traditional mold embossing technology, such as low controllability of microstructure distribution, and the damage to the surface integrity of materials caused by micro-milling. It improves the forming efficiency of pits, grooves, and biomimetic "ridge" microstructures.

[0044] 3. This invention utilizes ultrasonic vibration-assisted continuous point pressing and / or scribing to form microstructures on metal surfaces. Because the effective cutting edge of the microneedle tool has rounded corners, stress concentration caused by the sharp point is avoided, ensuring that the original surface is not damaged when in contact with the workpiece. Furthermore, this microstructure forming method uses uniform material manufacturing, preventing burrs and other defects during processing. In addition, the introduction of ultrasonic vibration assistance means that the point-scribing process involves repeated impacts of the effective cutting edge on the material surface, increasing the hardness of the metal surface layer. Throughout the entire processing, the processing parameters of the microneedle tool and the ultrasonic vibration parameters remain stable, ensuring the stability of the internal quality of the formed groove (here, internal quality is judged by surface defects, surface roughness, and surface hardness), and improving the processing efficiency of the microstructure. Leveraging the advantages of high control freedom, processing efficiency, and high precision of a five-axis CNC machine tool, the processing accuracy and freedom of the microgroove are improved. By changing microneedle tools with different effective cutting edge shapes and adjusting the tool axis angle, continuous point pressing and / or scribing can produce the desired microstructures.

[0045] 4. The method of the present invention combines high precision, high surface quality and high efficiency.

[0046] In terms of precision: 1) From the perspective of positioning accuracy, the clamping and tool setting processes of micro-needle tools are exactly the same as those of standard tools. The automatic tool setting system carried by the five-axis linkage machine tool can be used to ensure positioning accuracy in the preparation work before processing; 2) From the perspective of processing accuracy requirements, micro-needle tools are controlled by high-precision five-axis linkage CNC machine tools. Once the processing parameters such as travel distance and feed rate are set, the process of forming microstructures by dot-matrix is ​​quantitative. The real-time processing status of micro-needle tools (position, load, processing parameters, etc.) can also be directly seen on the control panel of the machine tool, which helps to judge the stability of the processing process.

[0047] In terms of surface quality: the micro-needle tool dot-and-scratch forming microstructures is achieved by extruding metal materials to flow and produce plastic deformation. There is no obvious material accumulation on both sides, resulting in a relatively smooth surface of the microstructure with almost no burrs, scratches or other defects, and the surface roughness is also reduced compared to the unprocessed surface.

[0048] In terms of efficiency: Once the clamping method is determined in one setup for five-axis machining, it almost never needs to be changed again, avoiding errors caused by multiple clamping. After programming the toolpath according to the type and arrangement of the required microstructure, continuous machining can be achieved, resulting in high efficiency. Attached Figure Description

[0049] Figure 1 This is a flowchart of the forming method of the present invention.

[0050] Figure 2 This is a schematic diagram of the forming device of the present invention.

[0051] Figure 3 This is an example of the structural dimensions of the spherical microneedle cutter in the forming device of the present invention (the effective blade is spherical).

[0052] Figure 4 The figures show the trajectory diagram of the micro-needle tool used in this invention to process pits and grooves on a metal plate, as well as the actual micro-groove forming effect diagram. (a) shows the groove micro-structure formed by ultrasonic vibration-assisted dot-matrix forming; (b) shows the pit micro-structure formed by ultrasonic vibration-assisted dot-matrix forming; (c) shows the actual effect diagram (three-dimensional morphology diagram) of the micro-groove formed by the method of this invention; and (d) shows the actual effect diagram (top view) of the micro-groove formed by the method of this invention.

[0053] Figure 5 This is a schematic diagram of the biomimetic "ridge-like" microstructures obtained by overlapping and non-overlapping machining areas when using a microneedle tool with a spherical effective edge in this invention.

[0054] Figure 6 This is a schematic diagram of the microstructure for regional variable tool axis forming on a workpiece with a narrow and limited operable space according to the present invention.

[0055] Figure 7 The diagrams show the machining trajectories of incremental progressive and free-form surface tangent contact point normal-driven dot-matrix forming on thin-walled parts according to the present invention. (a) is a schematic diagram of the machining trajectory of incremental progressive continuous dot pressing forming, and (b) is a schematic diagram of the machining trajectory of variable angle continuous dot pressing forming.

[0056] Figure 8 The following are schematic diagrams of the continuous point-press forming microstructures obtained when using micro needle tools with different effective blade shapes according to the method of the present invention: (a) is a schematic diagram of a triangular microgroove structure, (b) is a schematic diagram of a U-shaped microgroove structure, (c) is a schematic diagram of a rectangular microgroove structure, and (d) is a schematic diagram of a trapezoidal microgroove structure. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0058] like Figure 1 As shown, the five-axis linkage dot-and-scratch forming method for metal surface microstructures under complex working conditions provided by the present invention includes the following steps:

[0059] Step 1: Preparation before processing;

[0060] Step 1.1 Engineering model design and modeling;

[0061] Extract the shape and size of the workpiece to be processed, as well as the cross-section, guide lines, position, and arrangement of the microstructures to be processed. Construct a CAD model of the workpiece and the microstructures, and import it into CAM software.

[0062] The cutting edge shape of the microneedle tool is designed according to the shape of the microstructure to be processed. The cutting edge size range of the microneedle tool is selected according to the size of the microstructure to be processed. The straight shank size of the microneedle tool, including diameter and length, is selected according to the size of the processing space available for the workpiece. After the microneedle tool is designed, the microneedle tool is manufactured according to the design results. A CAD model of the microneedle tool is built based on the design results. A tool library is created in the CAM software, and the CAD models of the constructed microneedle tools are numbered sequentially and placed into the library.

[0063] Step 1.2: Compile machining project templates for different microstructures under normal and complex working conditions, and import them into a five-axis CNC machine tool;

[0064] Step 1.2.1 involves matching the CAD model of the microstructure constructed in Step 1.1 with the applicable processing method, and compiling processing project templates for various types of microstructures under normal working conditions:

[0065] If the microstructure to be processed is a pit microstructure, the point pressing method is used for processing, that is, the micro needle tool presses the metal material on the surface of the workpiece along the axis to finally form it. Based on this processing method, the micro needle tool processing trajectory is generated in the CAM software according to the CAD model of the micro needle tool, the workpiece to be processed and the microstructure constructed in step 1.1, and a point pressing processing toolpath program with adjustable parameters is compiled, named and saved as the point pressing processing project template corresponding to the pit microstructure under normal working conditions.

[0066] If the microstructure to be processed is a microgroove structure, then the engraving method is used for processing. That is, the tool position of the micro needle tool is offset inward relative to the workpiece surface (i.e., relative to the material inside the workpiece surface) by a certain distance, and then the metal material is continuously extruded along the guide line direction of the microstructure to finally form it. Based on this processing method, the micro needle tool processing trajectory is generated in the CAM software according to the CAD model of the micro needle tool, the workpiece to be processed and the microstructure constructed in step 1.1, and the parameter adjustable engraving processing toolpath program is compiled, named and saved as the engraving processing project template corresponding to the microgroove structure under normal working conditions.

[0067] If the microstructure to be processed is a biomimetic "ridge-like" microstructure, then the processing is carried out by overlapping point pressing and / or scribing in the processing area. There is no need to repeatedly compile the processing toolpath program. The relevant toolpath program in the processing project template corresponding to the pit microstructure and / or microgroove structure under normal working conditions can be directly called.

[0068] Thus, processing project templates for various types of microstructures under normal working conditions are obtained;

[0069] Step 1.2.2 Based on the processing project template for normal working conditions compiled in Step 1.2.1, compile a processing project template for complex working conditions;

[0070] If the microstructure to be machined places the microneedle tool in a narrow and confined space, a point-and-click machining method with variable tool axis angle is adopted in a segmented manner. That is, by changing the position of the contact point between the microneedle tool and the workpiece surface at the effective cutting edge of the tool, the microneedle tool and the central water-outlet ultrasonic tool holder are moved away from the workpiece to avoid interference and collision. At this time, based on the machining project templates corresponding to various types of microstructures under normal working conditions obtained in step 1.2.1, a modification program segment related to the machining space size is added to adjust the tool axis angle parameters, which facilitates point-and-click machining with variable tool axis angle, and the machining project templates corresponding to various types of microstructures under the condition of limited machining space are obtained.

[0071] If the microstructure to be machined is on a free surface, a dot-mapping machining method is adopted to keep the direction of the micro-needle tool axis consistent with the normal vector of the cutting contact point. At this time, based on the machining project templates corresponding to various types of microstructures under normal working conditions obtained in step 1.2.1, a modification program segment related to the curvature of the workpiece surface is added to adjust the projection vector and tool axis angle parameters, so as to facilitate the dot-mapping machining method that keeps the tool axis consistent with the normal vector of the cutting contact point, and obtain the machining project templates corresponding to various types of microstructures on the free surface.

[0072] If the microstructure to be machined is on a thin-walled, easily deformable workpiece, a progressive dot-mapping method should be used, where the microstructure is machined layer by layer along its depth. When machining microstructures progressively layer by layer along its depth, the depth of each layer should be determined based on the thickness of the thin-walled workpiece, the material, and the dimensions of the microstructure. The workpiece deformation should ideally be controlled within 5% of the microstructure depth. In this case, based on the machining project templates for various types of microstructures obtained in step 1.2.1 under normal working conditions, a modification program segment related to the workpiece wall thickness, used to adjust the depth of cut and step distance parameters, is added to facilitate progressive dot-mapping machining and obtain the machining project templates for various types of microstructures on thin-walled, easily deformable workpieces.

[0073] Thus, processing project templates for various types of microstructures under complex working conditions were obtained.

[0074] Step 1.2.3 After converting the machining project templates corresponding to various types of microstructures under normal and complex working conditions obtained in Steps 1.2.1 and 1.2.2 into file types that can be recognized by five-axis CNC machine tools using existing post-processing methods, import them into the five-axis CNC machine tool.

[0075] Step 1.3 Select processing parameters;

[0076] Select machining parameters, including the feed rate and depth of the microneedle tool, as well as the ultrasonic amplitude and ultrasonic vibration frequency.

[0077] During the dot-matrix forming process, the spindle of the five-axis CNC machine tool is locked and can move linearly along the x, y, and z directions. The metal workpiece is clamped on the worktable of the five-axis CNC machine tool and rotates along the A and C axes. Appropriate feed rates and depths of cut are selected based on the material, thickness, and machining space of the metal workpiece. When using ultrasonic generators for assisted machining, appropriate ultrasonic amplitude and frequency should also be selected to reduce tool load. Specifically, for high-hardness, difficult-to-machine metals such as titanium alloys, the feed rate should be optimized to minimize wear on the micro-needle tool. The feed rate should not exceed 40 mm / min. Considering that a lower feed rate results in a longer processing time, the feed rate should ideally not be lower than 2 mm / min while meeting processing requirements. When machining microstructures on thin-walled parts such as engine blades, to reduce deformation errors, the feed rate and depth of indentation can be reduced to lessen the pressure on the workpiece surface during each machining operation. Excessive depth of indentation not only causes workpiece deformation but also increases the tool load, affecting the lifespan of the microneedle tool. When machining in confined spaces, the feed rate should ideally be lower than 10 mm / min to prevent interference and collisions. The amplitude of the ultrasonic auxiliary device should be adjusted according to the size of the microstructure being machined. Excessive amplitude can easily cause surface cracking during dot-matrix forming of microstructures, while insufficient amplitude will not provide impact strengthening, affecting the surface quality of the microstructure. For microstructures with a depth of 10-999 micrometers, the recommended feed rate for the microneedle tool is 2–40 mm / min, the depth of indentation is 0–200 μm, the ultrasonic amplitude is 1.5–5 μm, and the ultrasonic vibration frequency is 20–40 kHz.

[0078] Step 2: Fabricate microstructures on the test specimen;

[0079] Step 2.1 Test Specimen Installation:

[0080] The test piece is fixed on the worktable of a five-axis CNC machine tool, and the test piece is aligned as required using a contact probe.

[0081] Step 2.2 Microneedle Tool Installation:

[0082] The microneedle tools made in step 1 are adjusted and installed sequentially according to the CAD model numbers of the microneedle tools in the tool library specified in the CAM software in step 1. These microneedle tools include microneedle tools with different overhang lengths required in the transverse and longitudinal ultrasonic vibration directions, as well as microneedle tools with effective cutting edges of different shapes and sizes. Each microneedle tool is then set using the automatic tool setting system of the five-axis machine tool and placed in the tool library of the five-axis CNC machine tool in sequence.

[0083] Step 2.3 Program execution:

[0084] Select a matching microneedle tool from the tool library based on the shape and size of the microstructure to be processed. For point-press forming pit microstructures, select a microneedle tool with the required overhang length for longitudinal vibration. For scribing forming groove microstructures, select a microneedle tool with the required overhang length for transverse vibration.

[0085] Input the machining parameters selected in step 1.3, and call the machining toolpath program from the machining project template imported from the five-axis CNC machine tool in step 1.2 according to the working conditions and microstructure type. Perform five-axis linkage dot-mapping machining of the microstructure on the test piece. During the machining process, the five-axis CNC machine tool judges in real time whether the microneedle tool is worn or broken based on the stability of the force signal collected by the force measuring table, so as to replace the tool in time.

[0086] Step 3: Microstructure forming inspection to determine microstructure processing parameters;

[0087] The cross-sectional dimensions and surface roughness of the microstructures machined on the test piece were measured using an automatic zoom three-dimensional surface measuring instrument. For microstructures that met the requirements for dimensional accuracy and surface roughness, the surface hardness was tested with a hardness tester. Finally, the microstructure processing parameters that meet the requirements for dimensional accuracy, surface roughness and hardness were determined.

[0088] Step 4: Machining microstructures on the workpiece;

[0089] Based on the microstructure processing parameters determined in step 3, the required microstructure is processed on the workpiece using a five-axis CNC machine tool using the same method as in step 2.

[0090] like Figure 2 As shown, the present invention also provides a five-axis linkage dot-matrix forming device for realizing the forming method of the present invention for metal surface microstructure under complex working conditions, including a five-axis CNC machine tool 1, an ultrasonic energy generator 3, a center water outlet ultrasonic tool holder (commercially available product, including receiving ring, transducer, and amplitude transformer, the receiving ring, transducer, and amplitude transformer are all built into the tool holder) 4, an ultrasonic energy transmission ring 5, and a micro needle tool 6.

[0091] The ultrasonic energy generator 3 is connected to the ultrasonic energy transfer ring 5, which is fixed on the headstock of the five-axis CNC machine tool 1. The lower end of the spindle of the five-axis CNC machine tool 1 is connected to the center-outlet ultrasonic tool holder 4, which is connected to the micro-needle tool 6. The micro-needle tool 6 directly acts on the workpiece 2, which is clamped on the worktable of the five-axis CNC machine tool 1. The ultrasonic energy transfer ring 5 and the center-outlet ultrasonic tool holder 4 do not directly contact each other; the distance between them is no more than 1 mm. However, it is necessary to ensure that the electromagnetic output ring on the ultrasonic energy transfer ring 5 is vertically aligned with the receiving ring on the center-outlet ultrasonic tool holder 4.

[0092] The ultrasonic energy generator 3 converts the AC power generated by the motor into ultrasonic energy, which is then transmitted to the central water-outlet ultrasonic tool holder 4 (including a receiving ring, transducer, and amplitude transformer) through the ultrasonic energy transmission ring 5. The central water-outlet ultrasonic tool holder 4 converts the ultrasonic energy into ultrasonic mechanical vibration, which is transmitted to the tip of the micro-needle tool 6. A resonant point is formed at the tip through the amplitude transformer, resulting in a very large impact acceleration. The micro-needle tool 6 applies ultrasonic vibration and static pressure to the surface of the workpiece 2 for continuous processing. During processing, it moves on the surface of the workpiece 2 through the spindle feed of the five-axis CNC machine tool 1, and its processing angle relative to the workpiece 2 is controlled by the oscillation of the rotary axis of the five-axis CNC machine tool 1. The ultrasonic energy and the spindle motion of the five-axis CNC machine tool 1 combine to vibrate at high frequency along the feed direction, continuously hammering the surface of the workpiece 2. Through point-by-point cumulative deformation, the microstructure is finally formed.

[0093] Example of the structure and dimensions of microneedle cutter 6 Figure 3 As shown, the tool consists of two parts: a straight shank tool holder 7 and a tapered cutting edge 8. The entire tool is made of a high-hardness cemented carbide (e.g., tungsten-cobalt alloy). The effective cutting edge of the tapered cutting edge 8 in the figure is a partially micro-diameter spherical structure. When the angle between the tool axis and the workpiece is changed within a certain range, the cross-sectional shape of the microstructure produced by the dot-machining method is still close to spherical. Therefore, it can ensure that the effective cutting edge shape of the micro-needle tool can be well replicated when the microstructure is machined by dot-machining with a variable tool axis angle. The micro-diameter refers to the effective cutting edge diameter of the ball head being less than 200μm. The straight shank tool holder 7 can be selected with different diameters according to the actual operable space and the clamping range of the spring collet; the taper of the tapered cutting edge 8 is determined by the cross-sectional dimensions of the microstructure to be processed. Different width-to-depth ratio microstructures will be designed according to different needs. These microstructures with different width-to-depth ratios are reflected on the effective cutting edge of the micro needle tool, which corresponds to different cutting edge tapers. Therefore, the taper of the tapered cutting edge 8 can be changed according to the required microgroove size; the overall length of the tool is related to the workpiece height and the direction of ultrasonic vibration. The overall length of the tool should be determined in combination with the space range available for processing the formed microstructure and the need for adjusting the direction of ultrasonic vibration to ensure that all positions on the workpiece that need to be processed can be processed, and also to ensure that the micro needle tool does not interfere with the workpiece after it is inserted into the workpiece.

[0094] The microneedle cutter 6 is detachably connected to the central water outlet ultrasonic scalpel holder 4. The effective cutting edge shape of the microneedle cutter 6 is not fixed; it can be replaced with a microneedle cutter of a matching shape and size according to the shape and size of the workpiece and the desired microstructure to be formed. For example, [example...]. Figure 8 As shown. To avoid stress concentration caused by the tip, the effective edge of the microneedle tool 6 in this invention uses a rounded corner transition regardless of its shape.

[0095] The method of using the five-axis linkage dot-and-scrib forming device for metal surface microstructures under complex working conditions according to the present invention is as follows:

[0096] First, clamp the workpiece on the worktable, connect the ultrasonic energy transfer ring and the micro-needle tool to the spindle of the five-axis CNC machine tool 1, align the workpiece 2, and set the micro-needle tool 6.

[0097] Then, the ultrasonic-assisted equipment is activated to generate axial high-frequency vibration;

[0098] Next, run the pre-set toolpath file on the five-axis CNC machine tool 1 and adjust the micro needle tool to the specified machining position;

[0099] Finally, the micro-needle tool 6 is driven by the spindle feed of the five-axis CNC machine tool 1 to perform continuous point pressure machining of the microstructure on the surface of the workpiece 2: such as Figure 4 As shown in Figure (a), the ultrasonic vibration direction is adjusted to the transverse direction. The spindle of the five-axis CNC machine tool is offset by a groove depth in the z-axis direction and then fed along the x or y-axis direction. A groove microstructure is machined along the workpiece surface using a scribing method. Figure 4 As shown in Figure (b), the microneedle tool 6 performs five-axis linkage dot-machining on a metal plate. The ultrasonic vibration direction is adjusted to the longitudinal direction, and the spindle of the five-axis CNC machine tool 1 feeds along the z-axis. The microstructure of the pit is machined by vertically pressing the surface of the metal plate using a point-pressing method. The geometry and size of the machined microstructure are the same as the geometry and size of the effective cutting edge of the microneedle tool 6, and gradually change with different pressing depths. Therefore, microstructures of different depths can be machined by changing the pressure of the microneedle tool 6 on the workpiece surface.

[0100] Figure 4 Figures (c) and (d) show the forming apparatus and method using the present invention. Figure 3 The image shown is an actual result of microgrooving on a titanium alloy plate surface using a microneedle tool (photographed by an automatic zoom 3D surface measuring instrument). The required microgroove depth is 40 μm, with a width-to-depth ratio of 2:1. The machining process uses a spindle feed rate of 8 mm / min, an ultrasonic frequency of 27 kHz, and an ultrasonic vibration amplitude of 1.5 μm. From the 3D morphology and top view of the microgroove, the machined microgroove structure exhibits good forming quality, with few surface defects such as burrs. There is no obvious material accumulation in the contact area with the unmachined surface, and the machining error is within acceptable limits.

[0101] When creating microstructures by dot-mapping on a metal plate, the microneedle tool should be as perpendicular as possible to the surface of the metal plate during the machining process. The same microneedle tool can be used to create different types of microstructures by dot-mapping according to different toolpath trajectories, such as... Figure 5As shown, six different types of biomimetic "ridge-like" microstructures were obtained using a microneedle tool 6 with a partially micro-diameter ball tip, under conditions of non-overlapping and overlapping machining areas, through a point-press method. It should also be noted that to reduce tool wear and improve the service life of the microneedle tool, the feed rate during machining should be adjusted according to the size of the microneedle tool; the smaller the tool size, the lower the feed rate should be during point-and-point machining.

[0102] When machining materials with high hardness or thin, easily deformable materials, single-pass dot-mapping forming of microneedles places a heavy load on the tool and can cause workpiece deformation or even damage. In such cases, an incremental, continuous dot-mapping forming method can be adopted, performing microstructure machining in multiple layers according to the actual situation. Simultaneously, while ensuring the rigidity of the microneedle tool, the feed rate can be appropriately increased to compensate for the efficiency loss caused by layered machining. Figure 7 As shown in Figure (a).

[0103] By using five-axis linkage to ensure that the micro-needle tool axis direction always aligns with the normal vector of the cutting contact point for dot-machining, a surface microstructure array with good distribution control and consistency can be obtained on free-form surfaces, such as... Figure 7 As shown in (b).

[0104] Besides changing the toolpath, directly replacing the micro-needle tool 6 with different effective cutting edges can also create different types of microstructures on the surface of metal workpieces through a dot-and-scratch process. For example... Figure 8 Four different types of microgroove structures were obtained by continuous point pressing using micro needle tools with effective cutting sections of triangle, U-shape, rectangle and trapezoid.

[0105] Example:

[0106] The workpiece to be processed is a titanium alloy integral bladed disk simulation part. The width of the flow channel between adjacent blades is about 15mm and the blade height is 50mm. Under the premise of ensuring rigidity, partial spherical microgrooves with a width-to-depth ratio of 2:1 and a depth of 40μm need to be machined on the blade surface. This includes three complex working conditions: narrow and limited operating space, thin wall and easy deformation, and free surface.

[0107] Select The microneedle tool has an effective cutting edge of R0.04mm ball end and an overall tool length of 100mm. The microstructure arrangement on the blade (already marked on the initial modeling or design drawings) is divided into regular areas and narrow, confined areas, such as... Figure 6As shown, the corresponding program template is called to generate and post-process a toolpath file that can be recognized by a five-axis machine tool. After all the test devices are installed, the file is imported into the five-axis CNC machine tool. First, the micro-needle tool is driven by the normal vector of the contact point between the micro-needle tool and the surface where the micro-groove is located to carve and machine the micro-groove in the conventional area. Considering that the blade surface is a free surface, the tool axis direction of the micro-needle tool should always be consistent with the normal vector of the contact point during the machining of the micro-groove in the conventional area. Then, the position of the contact point between the micro-needle tool and the blade surface at the effective cutting edge of the tool is changed by the five-axis drive to keep the tool and tool holder at least 1 mm away from the workpiece, so as to machine the micro-groove in the narrow and restricted area without interference or collision. The normal vector drive refers to taking several equidistant points as tool contact points on the guide line of the formed micro-groove, and drawing the normal plane of the guide line through each contact point. When the tool axis vector of the micro-needle tool changes during machining, it always remains consistent with the normal plane at the contact point. In addition, since the blade part of the workpiece to be processed is a thin-walled and easily deformable structure, and the blade thickness does not exceed 2mm, it is advisable to determine whether it is necessary to call the relevant program segment in the micro-groove processing project template on the thin-walled and easily deformable workpiece to change the cutting depth and step distance based on the deformation of the blade during the dot-mapping process. The micro-groove with a depth of 40μm can be etched in two or more times to ensure that the deformation of the blade is controlled within 2μm.

[0108] It is important to note that the overall impeller flow channel space is small, the tool radius should not be too large, and the tool direction and the normal direction of the contact point should always be kept within a certain angle range and transition as smoothly as possible in order to improve the forming accuracy when performing dot-mapping microstructure machining on the blade surface without interference.

Claims

1. A five-axis linkage dot-and-scratch forming method for microstructures on metal surfaces under complex working conditions, characterized in that, Includes the following steps: Step 1: Preparation before processing; Step 1.1 Engineering model design and modeling; Design and manufacture microneedle tools, construct CAD models of microneedle tools and import them into CAM software; create a tool library in the CAM software and put the CAD models of the microneedle tools into the tool library after numbering them sequentially; Construct CAD models and microstructure CAD models of the workpiece to be processed and import them into CAM software; Step 1.2: Compile machining project templates for different microstructures under normal and complex working conditions and import them into a five-axis CNC machine tool; Step 1.2.1 involves matching the CAD model of the microstructure constructed in Step 1.1 with the applicable processing method, and compiling processing project templates for various types of microstructures under normal working conditions: If the microstructure is a pit microstructure, the point pressing method is used for processing. In the CAM software, the micro needle tool processing trajectory is generated based on the CAD model of the micro needle tool, the workpiece to be processed and the microstructure constructed in step 1.1, and the point pressing processing toolpath program with adjustable parameters is compiled, named and saved as the point pressing processing project template corresponding to the pit microstructure under normal working conditions. If the microstructure is a microgroove structure, it is processed by scribing. In the CAM software, the micro-needle tool processing trajectory is generated based on the CAD model of the micro-needle tool, the workpiece to be processed and the microstructure constructed in step 1.

1. A scribing processing toolpath program with adjustable parameters is compiled, named and saved as the scribing processing project template corresponding to the microgroove structure under normal working conditions. If the microstructure is a biomimetic "ridge-like" microstructure, then the overlapping point pressing and / or scribing processing method is adopted in the processing area, and the processing project template corresponding to the pit microstructure and / or microgroove structure under conventional working conditions is directly called. Step 1.2.2: Compile processing project templates for various types of microstructures under complex working conditions: If the microstructure to be machined places the microneedle tool in a narrow and confined space, then a dot-and-dash machining with regional variable tool axis angle is adopted. In the machining project templates corresponding to each type of microstructure under the normal working conditions obtained in step 1.2.1, a modification program segment related to the size of the machining space and used to adjust the tool axis angle parameters is added to obtain the machining project templates for each type of microstructure under the working conditions of limited machining space. If the microstructure to be machined is on a free surface, a dot-mapping machining method is adopted to keep the direction of the micro-needle tool axis consistent with the normal vector of the cutting contact point. In the machining project templates corresponding to each type of microstructure under normal working conditions obtained in step 1.2.1, a modification program segment related to the curvature of the workpiece surface and used to adjust the projection vector and tool axis angle parameters is added to obtain the machining project templates corresponding to each type of microstructure on the free surface. If the microstructure to be processed is on a thin-walled, easily deformable workpiece, then the microstructure is processed in a progressive dot-mapping manner by layering it along the depth. In the processing project templates corresponding to each type of microstructure under the normal working conditions obtained in step 1.2.1, a modification program segment related to the workpiece wall thickness is added to adjust the cutting depth and step distance parameters, so as to obtain the processing project templates corresponding to each type of microstructure on the thin-walled, easily deformable workpiece. Step 1.2.3 After converting the machining project templates corresponding to various types of microstructures under normal and complex working conditions obtained in Steps 1.2.1 and 1.2.2 into file types that can be recognized by the five-axis CNC machine tool, import them into the five-axis CNC machine tool. Step 1.3 Select processing parameters; Select processing parameters, including the feed rate of the microneedle tool, the depth of indentation, the ultrasonic amplitude, and the ultrasonic vibration frequency; Step 2: Fabricate microstructures on the test specimen; Based on the machining project template of the five-axis CNC machine tool imported in step 1.2.3, the tool library formulated in step 1.1, and the machining parameters selected in step 1.3, micro needle tools are installed on the five-axis CNC machine tool. After being installed and adjusted in place, the microstructure is machined on the test piece using the five-axis CNC machine tool. Step 3: Microstructure forming inspection to determine microstructure processing parameters; The forming quality of the microstructures processed on the test piece is inspected to determine the microstructure processing parameters that meet the requirements of dimensional accuracy, surface roughness and hardness. Step 4: Machining microstructures on the workpiece; Based on the microstructure processing parameters determined in step 3, the required microstructure is processed on the workpiece using a five-axis CNC machine tool using the same method as in step 2.

2. The five-axis linkage dot-matrix forming method for metal surface microstructures under complex working conditions according to claim 1, characterized in that, In step 1, the corresponding microneedle tool structure and size are designed according to the shape, size and processing space of the different microstructures to be processed.

3. The five-axis linkage dot-matrix forming method for metal surface microstructures under complex working conditions according to claim 1, characterized in that, In step 1.3, the feed rate and depth of the microneedle tool are selected based on the material, thickness, processing space, microneedle tool life, workpiece deformation error, and processing efficiency of the workpiece to be processed; the ultrasonic amplitude and ultrasonic vibration frequency are selected based on the surface quality requirements of the microstructure and the strength of the workpiece to be processed.

4. The five-axis linkage dot-matrix forming method for metal surface microstructures under complex working conditions according to claim 3, characterized in that, If the depth of the microstructure to be processed is 10-999 micrometers, the feed speed of the microneedle tool is 2-40 mm / min, the pressing depth is 0-200 μm, the ultrasonic amplitude is 1.5-5 μm, and the ultrasonic vibration frequency is 20-40 kHz.

5. The five-axis linkage dot-and-scratch forming method for metal surface microstructures under complex working conditions according to any one of claims 1-4, characterized in that, Step 2 is as follows: Step 2.1 Test piece installation: Fix the test piece on the worktable of the five-axis CNC machine tool, and use the contact probe to align the test piece as required; Step 2.2 Microneedle Tool Installation: Adjust and install the microneedle tools in sequence according to the CAD model numbers of the microneedle tools in the tool library specified in Step 1. These microneedle tools include microneedle tools with different overhang lengths required in the transverse and longitudinal ultrasonic vibration directions, as well as microneedle tools with effective cutting edges of different shapes and sizes. Use the automatic tool setting system of the five-axis machine tool to set each microneedle tool and place them in the tool library of the five-axis CNC machine tool in sequence. Step 2.3 Program Execution: Select a matching microneedle tool from the tool library according to the shape and size of the microstructure to be processed. For point-press forming pit microstructures, select a microneedle tool with the required overhang length for longitudinal vibration. For scribing forming groove microstructures, select a microneedle tool with the required overhang length for transverse vibration. Call and execute the appropriate processing project template according to the microstructure type and working conditions. Perform five-axis linkage point-scribing processing on the test piece. During the processing, the five-axis CNC machine tool judges in real time whether the microneedle tool is worn or broken based on the stability of the force signal collected by the force measuring table, so as to replace the tool in time.

6. The five-axis linkage dot-matrix forming method for metal surface microstructures under complex working conditions according to claim 5, characterized in that, Step 3 specifically involves using an automatic zoom three-dimensional surface measuring instrument to measure the cross-sectional dimensions and surface roughness of the microstructures processed on the test piece. For microstructures that meet the requirements for dimensional accuracy and surface roughness, a hardness tester is used to test the surface hardness. Finally, the microstructure processing parameters that meet the requirements for dimensional accuracy, surface roughness, and hardness are determined.

7. A five-axis linkage dot-matrix forming device for complex working conditions of metal surface microstructures implementing the five-axis linkage dot-matrix forming method according to any one of claims 1-6, characterized in that: Including five-axis CNC machine tools, ultrasonic energy generators, center-outlet ultrasonic tool holders, ultrasonic energy transfer rings, and micro-needle tools; The ultrasonic energy generator is connected to the ultrasonic energy transfer ring, which is fixed on the headstock of a five-axis CNC machine tool. The lower end of the spindle of the five-axis CNC machine tool is connected to the central water-emitting ultrasonic tool holder, which is connected to the micro-needle tool. The micro-needle tool directly acts on the workpiece to be processed. The ultrasonic energy transfer ring and the central water-emitting ultrasonic tool holder are not in direct contact and the gap is less than or equal to 1 mm. The electromagnetic output ring on the ultrasonic energy transfer ring is aligned vertically with the receiving ring of the central water-emitting ultrasonic tool holder. Microneedle cutters consist of a straight shank and a tapered cutting edge; the effective cutting edge shape and size of the tapered cutting edge are matched with the shape and size of the microstructure to be machined.

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