Five-axis linkage dot-scribing type forming method for metal surface microstructure under complex working conditions

Abstract

In order to solve the technical problems that an existing surface microstructure machining method is difficult to consider high precision, high surface quality, high efficiency, high adaptability, high controllability and low cost, the invention provides a five-axis linkage dot-scribing type forming method for a metal surface microstructure under a complex working condition. By utilizing the characteristics of small size and good replaceability of the microneedle cutter and combining the characteristics of high machining precision and high degree of freedom of the five-axis linkage numerical control machine tool, the pose of the microneedle cutter can be continuously and accurately adjusted through the five-axis linkage numerical control machine tool according to different complex working conditions; a required array microstructure can be machined on the surface of a metal workpiece under the complex working conditions that the operable space is narrow and limited, a free-form surface is formed, and a thin wall is prone to deformation, the defects that according to a traditional die imprinting technology, microstructure distribution controllability is low, and material surface integrity is damaged by micro-milling machining are overcome, and the microstructure forming efficiency is improved; and the method has the advantages of high precision, high surface quality and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of metal surface microstructure processing, and in particular to a forming method of a metal surface microstructure under complex working conditions. Background Art

[0002] A large number of engineering practices and bionics studies have shown that surface microstructures can give parts special surface properties. Common groove or pit microstructures have been widely studied for their effects in drag reduction, sealing and lubrication. The morphology optimization and arrangement of microstructures have a positive impact on the surface performance of parts, and have good application prospects in the fields of electromechanics, aerospace, and biomedicine. Although the sizes of bionic microstructures of different shapes are different, they are all at the micron level. Therefore, microstructure processing has certain requirements on the volume, precision and operating freedom of the forming equipment. It is difficult to have the characteristics of high precision, high surface quality and high efficiency.

[0003] So far, the processing methods of surface microstructures mainly rely on EDM, ion beam etching, laser processing, micro milling, grinding, and micro embossing technology. Although EDM, ion beam etching, and laser processing have high processing efficiency, the problems of surface ablation and oxidation, low processing accuracy, etc. caused by their processing cannot be ignored, and most of the equipment is expensive and the processing requirements are relatively stringent; micro milling and grinding belong to mechanical processing subtractive manufacturing, which can give full play to the high efficiency advantages of multi-axis CNC processing, but the edges of the processed microstructures will inevitably produce defects such as burrs and scratches, which destroy the surface integrity of the microstructure and make it difficult to ensure the stability of the workpiece surface, especially the microstructure quality; the microstructure obtained by micro embossing technology has high surface quality, but the manufacturing cost is high, and the shape of the microstructure is limited by the imprinting mold, and the distribution controllability is not high.

[0004] Therefore, it is urgent to develop a metal surface microstructure processing technology with high precision, low cost, high efficiency and strong adaptability. Summary of the invention

[0005] In view of the technical problems in existing surface microstructure processing methods that it is difficult to achieve high precision, high surface quality, high efficiency, strong adaptability, high controllability and low cost at the same time, the present invention proposes a five-axis linkage dot-dash forming method for metal surface microstructures under complex working conditions.

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

[0007] The five-axis linkage dot-dash forming method for metal surface microstructure under complex working conditions is special in that it includes the following steps:

[0008] Step 1: Preparation before processing;

[0009] Step 1.1 Engineering model design and modeling;

[0010] Design and manufacture a microneedle tool, construct a CAD model of the microneedle tool and import it into CAM software; formulate a tool library in the CAM software and put the CAD model of the microneedle tool into the tool library after numbering it in sequence;

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

[0012] Step 1.2 Prepare the processing project templates of different microstructures under conventional working conditions and complex working conditions and import them into the five-axis CNC machine tool;

[0013] Step 1.2.1 matches the CAD model of the microstructure constructed in step 1.1 with the processing method applicable to it, and compiles the processing project template corresponding to each type of microstructure under conventional working conditions:

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

[0015] If the microstructure is a microgroove structure, it is processed by scratching. In the CAM software, the microneedle tool processing trajectory is generated according to the microneedle tool constructed in step 1.1, the workpiece to be processed and the CAD model of the microstructure, and a scratching tool path program with adjustable parameters is compiled and named and saved as a scratching processing project template corresponding to the microgroove structure under normal working conditions;

[0016] If the microstructure is a bionic "ridge-like" microstructure, the processing project template corresponding to the pit microstructure and / or microgroove structure under conventional working conditions is directly called by performing overlapping point pressing and / or scratching processing in the processing area;

[0017] Step 1.2.2 Prepare the processing project templates corresponding to various types of microstructures under complex working conditions:

[0018] If the microstructure to be processed places the microneedle tool in a narrow and confined space, a dot-dash processing method with a variable tool axis angle in different regions is used. In the processing project template corresponding to each type of microstructure under the conventional working condition obtained in step 1.2.1, a modification program segment for adjusting the tool axis angle parameter associated with the processing space size is added to obtain the processing project template for each type of microstructure under the working condition of confined processing space;

[0019] If the microstructure to be processed is on a free-form surface, a dot-dash processing method is used to keep the direction of the microneedle tool axis consistent with the normal vector of the contact point. In the processing project template corresponding to each type of microstructure under the conventional working condition obtained in step 1.2.1, a modification program segment associated with the workpiece surface curvature and used to adjust the projection vector and tool axis angle parameters is added to obtain the processing project template corresponding to each type of microstructure on the free-form surface;

[0020] If the microstructure to be processed is on a thin-walled, easily deformable workpiece, the microstructure is layered along the depth for progressive dotting and dashing processing. In the processing project template corresponding to each type of microstructure under the conventional working condition obtained in step 1.2.1, a modification program segment for adjusting the cutting depth and step parameters associated with the workpiece wall thickness is added to obtain the processing project template corresponding to each type of microstructure on the thin-walled, easily deformable workpiece;

[0021] Step 1.2.3 converts the processing project templates corresponding to various types of microstructures under conventional working conditions and complex working conditions obtained in steps 1.2.1 and 1.2.2 into file types recognizable by the five-axis CNC machine tool, and then imports them into the five-axis CNC machine tool;

[0022] Step 1.3: Select processing parameters;

[0023] Selecting processing parameters, including the feed speed of the microneedle tool, the pressing depth, the ultrasonic amplitude, and the ultrasonic vibration frequency;

[0024] Step 2: Processing microstructures on the test piece;

[0025] Based on the processing project template of the five-axis CNC machine tool imported in step 1.2.3, the tool library established in step 1.1, and the processing parameters selected in step 1.3, the microneedle tool is installed on the five-axis CNC machine tool, and after being installed and adjusted in place, the microstructure is processed on the test piece using the five-axis CNC machine tool;

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

[0027] Conduct forming quality inspection on the microstructure processed on the test piece to determine the microstructure processing parameters that meet the requirements of dimensional accuracy, surface roughness and hardness;

[0028] Step 4: machining a microstructure on the workpiece to be machined;

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

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

[0031] Furthermore, in step 1.3, the feed speed and pressing depth of the microneedle tool are selected according to 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 according to 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 microns, 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 is specifically as follows:

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

[0035] Step 2.2 Installation of microneedle tools: Adjust and install the microneedle tools in sequence according to the CAD model numbers of the microneedle tools in the tool library determined in step 1. These microneedle tools include microneedle tools with different suspension lengths required in the transverse and longitudinal ultrasonic vibration directions, and microneedle tools with effective blades of different shapes and sizes. Each microneedle tool is aligned using the automatic tool alignment system of the five-axis machine tool and placed in the tool library of the five-axis CNC machine tool in sequence.

[0036] Step 2.3 Program running: Select a matching microneedle tool from the tool library according to the shape and size of the microstructure to be processed. For the point-pressing type forming pit microstructure, use a microneedle tool with the required overhang length for longitudinal vibration. For the scratching type forming groove microstructure, use a microneedle tool with the required overhang length for lateral vibration. Call and execute the appropriate processing project template according to the microstructure type and working conditions, and perform five-axis linkage point-and-dash processing of the microstructure on the test piece. During the processing, the five-axis CNC machine tool determines in real time whether the microneedle tool is worn or broken based on the stability of the force signal collected by the force platform, so as to facilitate timely replacement of the tool.

[0037] Furthermore, step 3 is specifically as follows: 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, and then using a hardness tester to test the surface hardness of the microstructure whose dimensional accuracy and surface roughness meet the requirements, and finally determining the microstructure processing parameters that meet the dimensional accuracy, surface roughness and hardness requirements.

[0038] The present invention also provides a five-axis linkage dot-dash forming device for metal surface microstructures under complex working conditions for realizing the above-mentioned five-axis linkage dot-dash forming method, which is special in that it includes a five-axis CNC machine tool, an ultrasonic energy generator, a center-outlet ultrasonic tool handle, an ultrasonic energy transmission ring and a microneedle tool;

[0039] The ultrasonic energy generator is connected to the ultrasonic energy transmission ring, which is fixed on the headstock of the five-axis CNC machine tool. The lower end of the main shaft of the five-axis CNC machine tool is connected to the central water outlet ultrasonic tool handle, which is connected to the microneedle tool. The microneedle tool directly acts on the workpiece to be processed. The ultrasonic energy transmission ring and the central water outlet ultrasonic tool handle are not in direct contact, and the interval is less than or equal to 1mm. The electromagnetic output ring on the ultrasonic energy transmission ring is aligned with the receiving ring of the central water outlet ultrasonic tool handle.

[0040] The microneedle tool is composed of a straight-shank tool rod and a tapered blade; the effective blade shape and size of the tapered blade match the shape and size of the microstructure to be processed.

[0041] The beneficial effects of the present invention are:

[0042] 1. The forming method of the present invention is carried out on the basis of five-axis linkage processing, which combines the process parameters with the actual working conditions more closely. By changing different processing parameters and planning different paths, it is possible to use a microneedle tool (a microneedle tool here refers to a batch of tools with the same effective blade shape and size. The tools have different overhang lengths and are switched with the help of the tool library and automatic tool changing system of the five-axis CNC machine tool) to complete the forming of micron-level pits, grooves and bionic "ridge-like" microstructures through point pressing and / or engraving, thereby reducing manufacturing costs and is not limited to processing on conventional workpieces such as flat plates and rotating bodies.

[0043] 2. The present invention utilizes the small size and good replaceability of microneedle tools, combined with the high processing precision and high degree of freedom of five-axis linkage CNC machine tools. The five-axis linkage CNC machine tools can continuously and accurately adjust the position of microneedle tools for different complex working conditions, and can process the required array microstructures on the surface of metal workpieces with complex working conditions such as narrow and limited operating space, free curved surfaces, and thin walls that are easy to deform. The present invention overcomes the shortcomings of low controllability of microstructure distribution in traditional mold imprinting technology and micro-milling processing that destroys the integrity of the material surface, and improves the forming efficiency of pits, grooves, and bionic "ridge-like" microstructures.

[0044] 3. The present invention utilizes ultrasonic vibration to assist in continuous point pressing and / or scratching to form metal surface microstructures. Since the effective edge of the microneedle tool is rounded, stress concentration caused by the tip is avoided, ensuring that the original surface is not damaged when in contact with the workpiece surface. The microstructure forming method is equal material manufacturing, and no defects such as burrs will be generated during the processing. In addition, after the introduction of ultrasonic vibration assistance, the point-scratching forming process will be accompanied by repeated impacts of the effective edge of the tool on the material surface, thereby improving the hardness of the surface layer of the metal material. During the entire processing process, the processing parameters and ultrasonic vibration parameters of the microneedle tool are stable, ensuring the stability of the internal quality of the formed groove (the internal quality here is based on surface defects, surface roughness and surface hardness as the basis for judgment), and improving the processing efficiency of the microstructure. The advantages of high control freedom, high processing efficiency and high precision of the five-axis linkage CNC machine tool are utilized to improve the processing accuracy and processing freedom of the microgroove. By replacing microneedle tools with effective edges of different shapes and adjusting the tool axis angle, continuous point pressing and or scratching can be used to process the desired microstructure.

[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 microneedle tools and standard tools are exactly the same. The automatic tool setting system carried by the five-axis linkage machine tool can be used to ensure the positioning accuracy in the preparation work before processing; 2) From the perspective of processing accuracy requirements, the microneedle tool is controlled by a high-precision five-axis linkage CNC machine tool. Once the processing parameters such as moving distance, feed speed, etc. are set, the process of dot-stroke forming microstructure is quantitative. The real-time processing status of the microneedle tool (position, load, processing parameters, etc.) can also be directly viewed on the control panel of the machine tool, which helps to judge the stability of the processing process.

[0047] Surface quality: The microstructure formed by the microneedle tool dot-scratch method is to make the metal material flow and produce plastic deformation through extrusion. There is no obvious material accumulation on both sides. The surface of the obtained microstructure is relatively smooth, with almost no defects such as burrs and scratches, and the surface roughness is also lower than that of the unprocessed surface.

[0048] Efficiency: After the clamping method is determined once for five-axis machining, there is almost no need to change it, avoiding the error caused by multiple clamping. After the tool path program is compiled according to the type and layout of the required microstructure, continuous machining can be achieved with high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a flow chart of the forming method of the present invention.

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

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

[0052] Figure 4 The present invention shows a schematic diagram of the trajectory of processing pit and groove microstructures on a metal plate using the same microneedle tool and an actual microgroove forming effect diagram, wherein (a) is a groove microstructure formed by ultrasonic vibration assisted dot-dash method, (b) is a pit microstructure formed by ultrasonic vibration assisted dot-dash method; (c) is an actual effect diagram (three-dimensional morphology diagram) of a microgroove formed by the method of the present invention; (d) is an actual effect diagram (top view) of a microgroove formed by the method of the present invention.

[0053] Figure 5 This is a schematic diagram of the bionic "ridge-like" microstructure obtained when the microneedle tool with a spherical effective edge is used in the present invention with overlapping and non-overlapping processing areas.

[0054] Figure 6 It is a schematic diagram of the microstructure formed by the variable cutter axis in different areas on a workpiece with a narrow and limited operating space according to the present invention.

[0055] Figure 7 Schematic diagram of the processing trajectory of incremental progressive and tangent contact point normal vector driven dot-dash forming on free-form surfaces on thin-walled parts according to the present invention, (a) is a schematic diagram of the processing trajectory of incremental progressive continuous point pressing forming, and (b) is a schematic diagram of the processing trajectory of variable angle continuous point pressing forming.

[0056] Figure 8 Schematic diagrams of the continuous point-pressing formed microstructures obtained when the method of the present invention is used with microneedle tools with effective blades of different shapes, (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 DESCRIPTION

[0057] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0058] like Figure 1 As shown, the five-axis linkage dot-dash forming method of metal surface microstructure under complex working conditions provided by the present invention comprises the following steps:

[0059] Step 1: Preparation before processing;

[0060] Step 1.1 Engineering model design and modeling;

[0061] The shape and size of the workpiece to be processed, the cross-section, guide line, position and arrangement of the microstructure to be processed are extracted, and the CAD model of the workpiece to be processed and the microstructure is constructed and imported into the CAM software.

[0062] The blade shape of the microneedle tool is designed according to the shape of the microstructure to be processed, the blade size range of the microneedle tool is selected according to the size of the microstructure to be processed, and the straight handle tool rod size of the microneedle tool is selected according to the size of the processing space available for the workpiece to be processed, including the diameter and length; after the microneedle tool is designed, the microneedle tool is manufactured according to the design results, and a CAD model of the microneedle tool is constructed based on the design results. A tool library is prepared in the CAM software and the constructed CAD models of the microneedle tool are numbered in sequence and then placed in.

[0063] Step 1.2 Prepare machining project templates for different microstructures under conventional and complex working conditions and import them into the five-axis CNC machine tool;

[0064] Step 1.2.1 matches the CAD model of the microstructure constructed in step 1.1 with the processing method applicable to it, and compiles the processing project template corresponding to each type of microstructure under conventional working conditions:

[0065] If the microstructure to be processed is a pit microstructure, point pressing is used for processing, that is, the microneedle tool squeezes the metal material on the surface of the workpiece along the axial direction to finally form it. Based on this processing method, the microneedle tool processing trajectory is generated in the CAM software according to the microneedle tool constructed in step 1.1, the CAD model of the workpiece to be processed and the microstructure, and a point pressing processing tool track program with adjustable parameters is compiled, which is named and saved as a 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, a scratching method is used for processing, that is, after the tool position of the microneedle tool is offset inwardly relative to the workpiece surface (i.e., the material internal direction relative to the workpiece surface) by a certain distance, the metal material is continuously extruded along the guide line direction of the formed microstructure to finally form it. Based on this processing method, the microneedle tool processing trajectory is generated in the CAM software according to the CAD model of the microneedle tool, the workpiece to be processed and the microstructure constructed in step 1.1, and a parameter-adjustable scratching tool trajectory program is compiled, which is named and saved as a scratching processing project template corresponding to the microgroove structure under normal working conditions;

[0067] If the microstructure to be processed is a bionic "ridge-like" microstructure, it is processed by overlapping point pressing and / or scratching in the processing area. There is no need to repeatedly compile the processing tool path program, and the relevant tool path program in the processing project template corresponding to the pit microstructure and / or microgroove structure under normal working conditions can be directly called.

[0068] At this point, the processing project templates corresponding to various types of microstructures under conventional working conditions are obtained;

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

[0070] If the microstructure to be processed places the microneedle tool in a narrow and confined space, a dot-dash processing method with a variable tool axis angle is used in different regions, that is, the microneedle tool and the center-outlet ultrasonic tool handle are kept away from the workpiece by changing the position of the contact point between the microneedle tool and the workpiece surface at the effective edge of the tool to avoid interference and collision. At this time, based on the processing project templates corresponding to various types of microstructures under conventional working conditions obtained in step 1.2.1, a modification program segment for adjusting the tool axis angle parameters associated with the processing space size is added to facilitate dot-dash processing with a variable tool axis angle, and obtain processing project templates corresponding to various types of microstructures under working conditions with limited processing space;

[0071] If the microstructure to be processed is on a free-form surface, a dot-stroke processing method is used to keep the tool axis direction of the microneedle tool consistent with the normal vector of the contact point. At this time, based on the processing project templates corresponding to various types of microstructures under normal working conditions obtained in step 1.2.1, a modification program segment associated with the surface curvature of the workpiece for adjusting the projection vector and tool axis angle parameters is added to facilitate the dot-stroke processing method in which the tool axis is consistent with the normal vector of the contact point, and the processing project templates corresponding to various types of microstructures on the free-form surface are obtained;

[0072] If the microstructure to be processed is on a thin-walled, easily deformable workpiece, the microstructure is layered along the depth for progressive dot-dash processing. When the microstructure is processed by progressive dot-dash processing along the depth, the pressing depth of each layer should be determined according to the thickness, material and size of the thin-walled workpiece, and the deformation of the workpiece should be controlled within 5% of the depth of the microstructure. At this time, based on the processing project templates corresponding to various types of microstructures under normal working conditions obtained in step 1.2.1, a modified program segment for adjusting the cutting depth and step parameters associated with the wall thickness of the workpiece is added to facilitate progressive dot-dash processing, and obtain processing project templates corresponding to various types of microstructures on thin-walled, easily deformable workpieces.

[0073] At this point, the processing project templates corresponding to various types of microstructures under complex working conditions have been obtained.

[0074] Step 1.2.3 converts the processing project templates corresponding to various types of microstructures under conventional working conditions 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 using existing post-processing methods, and then imports them into the five-axis CNC machine tool.

[0075] Step 1.3: Select processing parameters;

[0076] The processing parameters are selected, including the feed speed and pressing depth of the microneedle tool, as well as the ultrasonic amplitude and ultrasonic vibration frequency.

[0077] During the dot-dash forming process, the spindle of the five-axis CNC machine tool is in a locked state 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 of the five-axis CNC machine tool. The appropriate processing feed speed and pressing depth are selected according to the material, thickness and processing space of the metal workpiece. When using ultrasonic generators to assist processing, the appropriate ultrasonic amplitude and frequency should also be selected to reduce the tool load. The specific selection principle is: for high-hardness and difficult-to-process metal materials such as titanium alloys, the feed speed is best during processing to reduce the wear of the microneedle tool. Not more than 40mm / min; Considering that the feed speed is too low, the corresponding processing time is also longer, so under the premise of meeting the processing requirements, the feed speed should not be lower than 2mm / min; when processing microstructures on thin-walled parts such as engine blades, in order to reduce deformation errors, the pressure on the workpiece surface during each processing can be reduced by reducing the feed speed and the pressing depth, because too large a pressing depth will not only cause deformation problems of the workpiece, but also increase the tool load, affecting the service life of the microneedle tool; when processing in a narrow space, the feed speed should be lower than 10mm / min to prevent interference and collision. The amplitude of the ultrasonic auxiliary device should be adjusted according to the size of the processed microstructure. If the amplitude is too large, it is easy to cause the surface of the workpiece to break when the dot-stroke forming microstructure is formed. If the amplitude is too small, it will not play an impact strengthening role, affecting the surface quality of the microstructure. For microstructures with a depth of 10-999 microns, the recommended feed speed of the microneedle tool is 2-40mm / min, the pressing depth is 0-200μm, the ultrasonic amplitude is 1.5-5μm, and the ultrasonic vibration frequency is 20-40kHz.

[0078] Step 2: Processing microstructures on the test piece;

[0079] Step 2.1 Test piece installation:

[0080] Fix the test piece on the working table of the five-axis CNC machine tool, and use the contact probe to align the test piece as required.

[0081] Step 2.2 Microneedle tool installation:

[0082] The microneedle tools prepared in step 1 are adjusted and installed in sequence 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, and microneedle tools with effective blades of different shapes and sizes. Each microneedle tool is aligned using the automatic tool alignment 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 running:

[0084] Select a matching microneedle tool from the tool library according to the shape and size of the microstructure to be processed. For the point-pressing type pit microstructure, a microneedle tool with the required overhang length for longitudinal vibration is selected. For the scoring type groove microstructure, a microneedle tool with the required overhang length for transverse vibration is selected.

[0085] Input the processing parameters selected in step 1.3, call the processing tool path program from the processing project template imported into the five-axis CNC machine tool in step 1.2 according to the working conditions and microstructure type, and perform five-axis linkage dot-dash processing of the microstructure on the test piece. During the processing, the five-axis CNC machine tool determines in real time whether the microneedle tool is worn or broken based on the stability of the force signal collected by the force platform, 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 processed on the test piece are measured using an automatic zoom three-dimensional surface measuring instrument. For microstructures that meet the requirements for dimensional accuracy and surface roughness, a hardness tester is used to test the surface hardness. Ultimately, the microstructure processing parameters that meet the requirements for dimensional accuracy, surface roughness and hardness are determined.

[0088] Step 4: machining a microstructure on the workpiece to be machined;

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

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

[0091] The ultrasonic energy generator 3 is connected to the ultrasonic energy transmission ring 5, which is fixed on the headstock of the five-axis CNC machine tool 1. The lower end of the main shaft of the five-axis CNC machine tool 1 is connected to the central water outlet ultrasonic tool handle 4, which is connected to the microneedle tool 6. The microneedle tool 6 directly acts on the workpiece 2, and the workpiece 2 is clamped on the working table of the five-axis CNC machine tool 1. There is no direct contact between the ultrasonic energy transmission ring 5 and the central water outlet ultrasonic tool handle 4, and the interval between the two is not greater than 1mm, but it is necessary to ensure that the electromagnetic output ring on the ultrasonic energy transmission ring 5 and the receiving ring of the central water outlet ultrasonic tool handle 4 are aligned up and down.

[0092] The ultrasonic energy generator 3 converts the AC power generated by the motor into ultrasonic energy, and transmits it to the central water-outlet ultrasonic tool handle 4 (including a receiving ring, a transducer, and a variable amplitude rod) through the ultrasonic energy transmission ring 5; the central water-outlet ultrasonic tool handle 4 converts the ultrasonic energy into ultrasonic mechanical vibration and transmits it to the tip of the microneedle tool 6, and forms a resonance point at the tip through the variable amplitude rod to obtain a very large impact acceleration; the microneedle tool 6 applies ultrasonic vibration and static pressure to the surface of the workpiece 2 for continuous processing, and during processing, it moves on the surface of the workpiece 2 through the main shaft feed of the five-axis CNC machine tool 1, and controls its processing angle relative to the workpiece 2 through the swing of the rotating axis of the five-axis CNC machine tool 1; after the ultrasonic energy is combined with the main shaft movement of the five-axis CNC machine tool 1, it vibrates at a high frequency along the feed direction, continuously hammers the surface of the workpiece 2, and finally forms the microstructure through point-by-point cumulative deformation.

[0093] The structure and size of the microneedle tool 6 are as follows Figure 3 As shown, it consists of a straight shank shank 7 and a tapered blade 8. The overall material of the tool is a cemented carbide with relatively high hardness (such as tungsten-cobalt alloy). The effective edge of the tapered blade 8 in the figure is a partial micro-diameter spherical structure. At this time, when the angle between the tool shaft and the workpiece is changed within a certain range, the cross-sectional shape of the microstructure processed by the dot-dash method is still close to a sphere. Therefore, it can be ensured that the effective blade shape of the microneedle tool can be better replicated when the microstructure is processed by the dot-dash method with a changed tool shaft angle; the micro-diameter refers to the effective blade diameter of the ball head being less than 200μm. The straight-shank tool rod 7 can select different diameters according to the actual operable space and the clamping range of the spring chuck; the taper of the conical blade 8 is determined by the cross-sectional size of the microstructure to be processed. Microstructures with different aspect ratios will be designed according to different needs. These microstructures with different aspect ratios are reflected on the effective blade of the microneedle tool, which corresponds to different blade tapers. Therefore, the taper of the conical blade 8 can be changed according to the required microgroove size; the overall length of the tool is related to the workpiece height and the ultrasonic vibration direction. The overall length of the tool should be determined in combination with the spatial range of the formed microstructure available for processing and the need to adjust the ultrasonic vibration direction to ensure that all positions on the workpiece where the microstructure needs to be processed can be processed, and that the microneedle tool does not interfere with the workpiece after it is inserted into the workpiece.

[0094] The microneedle tool 6 is detachably connected to the central water outlet ultrasonic tool handle 4. The effective blade shape of the microneedle tool 6 is not fixed, and the microneedle tool with a shape and size matching the shape and size of the workpiece and the desired microstructure can be replaced, for example Figure 8 In order to avoid stress concentration caused by the tip, the effective edge of the microneedle tool 6 in the present invention adopts rounded transition regardless of its shape.

[0095] The method of using the five-axis linkage dot-dash forming device for metal surface microstructure under complex working conditions of the present invention is:

[0096] First, clamp the workpiece on the work surface, connect the ultrasonic energy transmission ring and the microneedle tool to the main shaft of the five-axis CNC machine tool 1, align the workpiece 2, and align the microneedle tool 6;

[0097] Then, the ultrasonic auxiliary device is started to generate axial high-frequency vibration;

[0098] Next, the preset tool path file is run on the five-axis CNC machine tool 1 to adjust the microneedle tool to the specified processing position;

[0099] Finally, the microneedle tool 6 is driven to act on the surface of the workpiece 2 through the main shaft feed of the five-axis CNC machine tool 1 to perform microstructure continuous point pressure processing: Figure 4 As shown in Figure (a), the ultrasonic vibration direction is adjusted to the horizontal direction, and the main axis of the five-axis CNC machine tool 1 is offset in the z-axis direction by a groove depth distance and then fed in the x-axis or y-axis direction, and a groove microstructure is machined along the surface of the workpiece by a scratching method; Figure 4 As shown in the middle (b), the microneedle tool 6 performs five-axis linkage dot-dash processing on the metal plate, adjusts the ultrasonic vibration direction to the longitudinal direction, and the main axis of the five-axis CNC machine tool 1 feeds along the z-axis direction, and uses point pressure to vertically squeeze the surface of the metal plate to process the pit microstructure. The geometric shape and size of the processed microstructure are the same as the geometric shape and size of the effective blade pressing part of the microneedle tool 6, and gradually change with the different pressing depths. Therefore, microstructures of different depths can be processed by changing the pressure of the microneedle tool 6 on the workpiece surface.

[0100] Figure 4 Figures (c) and (d) show the forming device and method of the present invention. Figure 3 The actual effect of the microneedle tool machining microgrooves on the surface of a titanium alloy plate (photographed by an automatic zoom 3D surface measuring instrument); the required microgroove depth is 40μm, the width-to-depth ratio is 2:1, the machine tool spindle feed speed is 8mm / min, the ultrasonic frequency is 27kHz, and the ultrasonic vibration amplitude is 1.5μm. From the 3D topography and top view of the microgroove, the machined microgroove structure has good forming quality, few surface defects such as burrs, no obvious material accumulation in the contact part with the unmachined surface, and the machining error is within an acceptable range.

[0101] When forming microstructures on a metal plate by dotting and dashing, the microneedle tool should be as perpendicular to the processing surface of the metal plate as possible during the processing. The same microneedle tool can process different types of microstructures by dotting and dashing according to different tool path trajectories, such as Figure 5As shown, six different types of bionic "ridge-like" microstructures are obtained by point pressing using a microneedle tool 6 whose effective blade is a part of a micro-diameter ball head, with non-overlapping and overlapping processing areas. At the same time, it should be noted that in order to reduce tool wear and increase the service life of the microneedle tool, the feed speed during processing should be adjusted according to the size of the microneedle tool. The smaller the tool size, the smaller the feed speed should be during point-and-dash processing.

[0102] When the hardness of the processed material is high or the thickness is thin and easy to deform, the load of the microneedle tool in a single dot-dash forming process is very large, and it will also cause the workpiece to deform or even damage the workpiece. At this time, the incremental progressive continuous dot-dash forming method can be used to perform microstructure processing in multiple layers according to the actual situation. At the same time, the feed speed can be appropriately increased under the premise of ensuring the rigidity of the microneedle tool to make up for the efficiency loss caused by layered processing, such as Figure 7 As shown in Figure (a).

[0103] Through five-axis linkage, the direction of the microneedle tool axis is always consistent with the normal vector of the cutting contact point for dot-dash processing, and a surface microstructure array with good distribution controllability and consistency can be obtained on the free-form surface, such as Figure 7 (b) as shown.

[0104] In addition to changing the tool path, directly replacing the micro-needle tool 6 with different effective edges can also be used to dot-dash process different types of microstructures on the surface of the metal workpiece. Figure 8 Four different types of microgroove structures were obtained by continuous point pressing using microneedle tools with effective blade cross-sections of triangle, U-shape, rectangle and trapezoid.

[0105] Example:

[0106] The workpiece to be processed is a titanium alloy integral blade disk simulation part. The flow channel width between adjacent blades is about 15mm and the blade height is 50mm. Under the premise of ensuring rigidity, it is necessary to machine partial spherical micro grooves with a width-to-depth ratio of 2:1 and a depth of 40μm on the blade surface, covering three complex working conditions: narrow and limited operating space, thin walls that are easy to deform, and free-form surfaces.

[0107] Selection The effective blade of the microneedle tool is the R0.04mm part of the ball head, and the overall length of the tool is 100mm. The microstructure layout position on the blade (which has been marked in the early modeling or design drawings) is divided into a conventional area and a narrow restricted area, such as Figure 6As shown, the corresponding program template is called to generate and post-process into a tool path file that can be recognized by the five-axis machine tool. After all the test devices are installed, they are imported into the five-axis CNC machine tool. First, the normal vector of the microneedle tool and the surface contact point where the microgroove is located is driven to carve and process the microgrooves in the conventional area. Considering that the blade surface is a free-form surface, the direction of the microneedle tool axis should always be consistent with the normal vector of the contact point during the microgroove processing in the conventional area; then the five-axis drive is used to change the position of the microneedle tool and the blade surface contact point on the effective edge of the tool so that the tool and the tool handle are at least 1mm away from the workpiece, and the microgrooves in the narrow and restricted area are processed without interference and collision. The normal vector drive refers to taking several equidistant points on the guide line of the formed microgroove as the tool contact points, and making the normal plane of the guide line through each contact point. When the tool axis vector of the microneedle tool changes during processing, it always keeps 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 deformed structure, the maximum thickness of the blade does not exceed 2 mm. Therefore, according to the deformation amount of the blade during the dot-dash processing process, it can be judged whether it is necessary to call the relevant program segments for changing the cutting depth and step length in the micro-groove processing project template on the thin-walled and easily deformed workpiece, and the micro-grooves with a depth of 40 μm are divided into two or more times to ensure that the deformation of the blade is controlled within 2 μm.

[0108] It should be noted that the space of the integral blade flow channel is small, the tool radius should not be too large, and the tool direction and the normal vector direction of the cutting contact point should always be kept in a certain angle range and transition as smoothly as possible to improve the forming accuracy when performing dot-dash processing of microstructures on the blade surface while avoiding interference.

Claims

1. A five-axis linkage dot-dash forming method for metal surface microstructures under complex working conditions, characterized in that: The following steps are involved: Step 1: Preparation before processing; Step 1.1 Engineering model design and modeling; Design and manufacture a microneedle tool, construct a CAD model of the microneedle tool and import it into CAM software; formulate a tool library in the CAM software and put the CAD model of the microneedle tool into the tool library after numbering it in sequence; Construct the CAD model of the workpiece to be processed and the CAD model of the microstructure and import them into the CAM software; Step 1.2 Prepare the processing project templates of different microstructures under conventional working conditions and complex working conditions and import them into the five-axis CNC machine tool; Step 1.2.1 matches the CAD model of the microstructure constructed in step 1.1 with the processing method applicable to it, and compiles the processing project template corresponding to each type of microstructure under conventional working conditions: If the microstructure is a pit microstructure, point pressure is used for processing. In the CAM software, the microneedle tool processing trajectory is generated according to the microneedle tool constructed in step 1.1, the workpiece to be processed and the CAD model of the microstructure, and a point pressure processing tool track program with adjustable parameters is compiled and named and saved as a point pressure processing project template corresponding to the pit microstructure under normal working conditions; If the microstructure is a microgroove structure, it is processed by scratching. In the CAM software, the microneedle tool processing trajectory is generated according to the microneedle tool constructed in step 1.1, the workpiece to be processed and the CAD model of the microstructure, and a scratching tool path program with adjustable parameters is compiled and named and saved as a scratching processing project template corresponding to the microgroove structure under normal working conditions; If the microstructure is a bionic "ridge-like" microstructure, the processing project template corresponding to the pit microstructure and / or microgroove structure under conventional working conditions is directly called by performing overlapping point pressing and / or scratching processing in the processing area; Step 1.2.2 Prepare the processing project templates corresponding to various types of microstructures under complex working conditions: If the microstructure to be processed places the microneedle tool in a narrow and confined space, a dot-dash processing method with a variable tool axis angle in different regions is used. In the processing project template corresponding to each type of microstructure under the conventional working condition obtained in step 1.2.1, a modification program segment for adjusting the tool axis angle parameter associated with the processing space size is added to obtain the processing project template for each type of microstructure under the working condition of confined processing space; If the microstructure to be processed is on a free-form surface, a dot-dash processing method is used to keep the direction of the microneedle tool axis consistent with the normal vector of the contact point. In the processing project template corresponding to each type of microstructure under the conventional working condition obtained in step 1.2.1, a modification program segment associated with the workpiece surface curvature and used to adjust the projection vector and tool axis angle parameters is added to obtain the processing project template corresponding to each type of microstructure on the free-form surface; If the microstructure to be processed is on a thin-walled, easily deformable workpiece, the microstructure is layered along the depth for progressive dotting and dashing processing. In the processing project template corresponding to each type of microstructure under the conventional working condition obtained in step 1.2.1, a modification program segment for adjusting the cutting depth and step parameters associated with the workpiece wall thickness is added to obtain the processing project template corresponding to each type of microstructure on the thin-walled, easily deformable workpiece; Step 1.2.3 converts the processing project templates corresponding to various types of microstructures under conventional working conditions and complex working conditions obtained in steps 1.2.1 and 1.2.2 into file types recognizable by the five-axis CNC machine tool, and then imports them into the five-axis CNC machine tool; Step 1.3: Select processing parameters; Selecting processing parameters, including the feed speed of the microneedle tool, the pressing depth, the ultrasonic amplitude, and the ultrasonic vibration frequency; Step 2: Processing microstructures on the test piece; Based on the processing project template of the five-axis CNC machine tool imported in step 1.2.3, the tool library established in step 1.1, and the processing parameters selected in step 1.3, the microneedle tool is installed on the five-axis CNC machine tool, and after being installed and adjusted in place, the microstructure is processed on the test piece using the five-axis CNC machine tool; Step 3: Microstructure forming inspection to determine microstructure processing parameters; Conduct forming quality inspection on the microstructure processed on the test piece to determine the microstructure processing parameters that meet the requirements of dimensional accuracy, surface roughness and hardness; Step 4: machining a microstructure on the workpiece to be machined; Based on the microstructure processing parameters determined in step 3, the required microstructure is processed on the workpiece to be processed using a five-axis CNC machine tool in the same method as step 2.

2. The five-axis linkage dot-dash forming method for metal surface microstructure 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 size of the different microstructures to be processed.

3. The five-axis linkage dot-dash forming method for metal surface microstructure under complex working conditions according to claim 1, characterized in that: In step 1.3, the feed speed and pressing depth of the microneedle tool are selected according to 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 according to the surface quality requirements of the microstructure and the strength of the workpiece to be processed.

4. The five-axis linkage dot-dash forming method for metal surface microstructure under complex working conditions according to claim 3, characterized in that: If the depth of the microstructure to be processed is 10-999 microns, 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-dash forming method for metal surface microstructure under complex working conditions according to any one of claims 1 to 4, characterized in that: Step 2 is as follows: Step 2.1 Test piece installation: Fix the test piece on the working table of the five-axis CNC machine tool, and use the contact probe to align the test piece as required; Step 2.2 Installation of microneedle tools: Adjust and install the microneedle tools in sequence according to the CAD model numbers of the microneedle tools in the tool library determined in step 1. These microneedle tools include microneedle tools with different suspension lengths required in the transverse and longitudinal ultrasonic vibration directions, and microneedle tools with effective blades of different shapes and sizes. Each microneedle tool is aligned using the automatic tool alignment system of the five-axis machine tool and placed in the tool library of the five-axis CNC machine tool in sequence. Step 2.3 Program running: Select a matching microneedle tool from the tool library according to the shape and size of the microstructure to be processed. For the point-pressing type forming pit microstructure, use a microneedle tool with the required overhang length for longitudinal vibration. For the scratching type forming groove microstructure, use a microneedle tool with the required overhang length for lateral vibration. Call and execute the appropriate processing project template according to the microstructure type and working conditions, and perform five-axis linkage point-and-dash processing of the microstructure on the test piece. During the processing, the five-axis CNC machine tool determines in real time whether the microneedle tool is worn or broken based on the stability of the force signal collected by the force platform, so as to facilitate timely replacement of the tool.

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

7. A five-axis linkage dash-stroke forming device for metal surface microstructures under complex working conditions for realizing the five-axis linkage dash-stroke forming method according to any one of claims 1 to 6, characterized in that: It includes a five-axis CNC machine tool, an ultrasonic energy generator, a center-outlet ultrasonic tool holder, an ultrasonic energy transfer ring and a micro-needle tool; The ultrasonic energy generator is connected to the ultrasonic energy transmission ring, which is fixed on the headstock of the five-axis CNC machine tool. The lower end of the main shaft of the five-axis CNC machine tool is connected to the central water outlet ultrasonic tool handle, which is connected to the microneedle tool. The microneedle tool directly acts on the workpiece to be processed. The ultrasonic energy transmission ring and the central water outlet ultrasonic tool handle are not in direct contact, and the interval is less than or equal to 1mm. The electromagnetic output ring on the ultrasonic energy transmission ring is aligned with the receiving ring of the central water outlet ultrasonic tool handle. The microneedle tool is composed of a straight-shank tool rod and a tapered blade; the effective blade shape and size of the tapered blade match the shape and size of the microstructure to be processed.

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