Design method of vibration reduction boring cutter

Abstract

The invention relates to a design method of a vibration reduction boring cutter. The design method comprises the steps that the size and shape of the boring cutter are determined; the boring cutter comprises a radial rod; a polygonal structure is designed on a radial rod, the polygonal structure comprises a plurality of rectangular planes, and the rectangular planes are sequentially connected to form a closed polygon; each rectangular plane has different side lengths and inclination angles; by adjusting the side length number, the length of each side, the inclination angle and the grinding mode of the polygonal structure, the spring rigidity and the damping characteristic of the polygonal structure serving as the tuned mass damper are optimized; and the vibration reduction effect of a mass-spring-damping system formed by the polygonal structure and the boring cutter is verified. A polygonal structure formed by a plurality of rectangular planes is designed on a radial rod, and each rectangular plane has different side lengths and inclination angles, so that the radial rod becomes a passive vibration reduction structure integrated with a plurality of tuned mass dampers. Compared with the scheme that an external damping device needs to be additionally arranged, the design does not need additional space or a complex structure, and the size limitation of the micro-small-diameter boring cutter is perfectly adapted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cutting machining, in particular to a design method of a damping boring tool. BACKGROUND

[0002] In the field of metal cutting machining, boring is widely used in the machining of various hole series parts as a high-precision machining method. Especially in the machining of small-diameter holes, cemented carbide boring tools are the first choice due to their high hardness and high wear resistance.

[0003] However, as the overhang length of the boring tool increases, its stiffness will decrease sharply, causing the boring tool to lose stability and vibrate intensively during machining. Such vibration not only produces visible vibration marks on the surface of the machined part, seriously affecting the machining quality, but also shortens the tool life and increases the production cost.

[0004] To solve the chatter problem of large-length-to-diameter ratio boring bars during cutting machining, various damping methods have been proposed in related technologies. For example, they can be roughly divided into two categories: one is to improve the dynamic parameters of the boring bar itself to improve its damping performance, such as increasing the stiffness of the boring bar, reducing the mass, and increasing the damping; the other is to consume vibration energy through additional structures to achieve the purpose of damping, such as built-in dynamic vibration absorbers, particle dampers, and impact dampers.

[0005] However, in the field of solid cemented carbide tools, especially for the damping problem of small-diameter boring tools, there are still many deficiencies in related technologies.

[0006] The current market design of damping boring bars is mostly suitable for larger-diameter boring tools, and the damping method is often achieved by increasing the diameter of the tool bar or reducing the spindle speed and feed rate. These methods not only waste materials and reduce production efficiency, but also cannot effectively achieve the damping effect in some working conditions. For large-diameter solid cemented carbide boring tools, active damping technology can solve the problem to some extent, but its complex structure and high cost limit its application in small-diameter boring tools. Especially for small-diameter cemented carbide boring tools, due to size limitations, external additional damping structures cannot be effectively installed.

[0007] At the same time, the commonly used built-in vibration absorber design is inside the boring bar, which is obviously not applicable to small-diameter boring tools. Although adjusting the machining parameters can alleviate the vibration problem to some extent, the parameter range for stable machining varies significantly under different machine tools, different machining materials, different boring tool length-to-diameter ratios, and different diameters, lacking universality. SUMMARY

[0008] Therefore, a design method of a damping boring tool is provided, which is suitable for small-diameter cemented carbide boring tools and has high-efficiency damping performance and strong universality.

[0009] A design method of a vibration-reducing boring tool, comprising:

[0010] determining the size and shape of the boring tool; wherein the boring tool comprises a shaft;

[0011] designing a polygonal structure on the shaft, the polygonal structure comprising a plurality of rectangular planes, the rectangular planes being connected in sequence to form a closed polygon; wherein each of the rectangular planes has different side length and inclination angle;

[0012] optimizing the spring stiffness and damping characteristics of the polygonal structure as a tuned mass damper by adjusting the number of side lengths, the length of each side, the inclination angle, and the grinding method of the polygonal structure;

[0013] verifying the vibration-reducing effect of the mass-spring-damper system composed of the polygonal structure and the boring tool.

[0014] In one embodiment, the designing of the polygonal structure on the shaft comprises:

[0015] using finite element analysis or modal analysis software to simulate the vibration characteristics of the polygonal structure under different parameters;

[0016] adjusting the geometric parameters of the polygonal structure according to the simulation results and determining the vibration-reducing effect.

[0017] In one embodiment, the designing of the polygonal structure on the shaft comprises:

[0018] defining the initial side length and inclination angle of each rectangular plane as a design variable;

[0019] using a parametric design method to generate polygonal structure models under different parameter combinations;

[0020] performing vibration characteristic simulation on each of the polygonal structure models and recording its natural frequency, mode shape, and damping ratio.

[0021] In one embodiment, the diameter of the shaft is less than or equal to 3mm, and the rotary diameter of the boring tool is less than or equal to 5mm.

[0022] In one embodiment, when the diameter of the shaft is 2mm-3mm, the number of side lengths of the radial cross-section of the shaft is 10-14, the radial width of the polygonal structure is 2.15mm-2.2mm, and the radial width of the polygonal structure is the maximum distance between adjacent parallel sides.

[0023] The inclination angle is 10°-20°, and the inclination angle is the circumferential angle of the shaft.

[0024] In one embodiment, the rectangular planes are arranged in a spiral or stepped manner around the boring tool axis.

[0025] In one embodiment, the vibration-reducing boring tool is a passive vibration-reducing tool.

[0026] In one embodiment, the optimization of the spring stiffness and damping characteristics of the tuning mass damper includes:

[0027] By changing the edge length and inclination angle of each rectangular plane in the polygonal structure, the moment of inertia with respect to different bending directions is adjusted.

[0028] Different grinding methods are selected to process the edges of the polygonal structure to change the surface roughness and stress distribution, thereby affecting the damping characteristics.

[0029] In one embodiment, the verification of the vibration-reducing effect of the mass-spring-damper system composed of the polygonal structure and the boring tool includes:

[0030] Boring tool samples with different polygonal structure parameters are made to ensure that all samples have consistent conditions except for the polygonal structure.

[0031] Under the same machining conditions, each sample is subjected to boring machining test.

[0032] The vibration amplitude and machining surface quality of each sample during machining are measured and compared to evaluate the vibration-reducing effect.

[0033] In one embodiment, the evaluation of the vibration-reducing effect includes:

[0034] Vibration sensors and surface quality detectors are used to monitor and record vibration data and machining surface quality in real time during machining.

[0035] Statistical analysis of the monitoring data is performed to obtain quantitative evaluation results of the vibration-reducing effect of each sample.

[0036] The quantitative evaluation results are compared with the preset standard to determine whether the vibration-reducing target is achieved.

[0037] In one embodiment, it further includes:

[0038] According to the verification results, the design parameters of the polygonal structure are iteratively optimized until the preset vibration-reducing effect and machining quality requirements are met.

[0039] The design method of the damping boring tool, by designing the radial rod into a polygonal structure composed of multiple rectangular planes, and each rectangular plane having different side length and inclination angle, makes the radial rod itself a passive damping structure integrated with multiple tuned mass dampers. Compared with the scheme in the related art that needs to attach external damping devices, this design does not need additional space or complex structure, and perfectly adapts to the size limitation of the small radial boring tool. At the same time, the polygonal structure changes the moment of inertia of the cross section relative to different bending directions, designs the bending stiffness matching the multi-directional vibration working conditions such as radial and axial directions, forms a wide frequency damping bandwidth, and solves the problem of poor single frequency damping effect of the traditional boring tool. By adjusting the number of side length, inclination angle and grinding mode of the polygonal structure, the spring stiffness and damping characteristics of the polygonal structure as a tuned mass damper are optimized, and then the polygonal structure of the radial rod is designed into a passive damping structure integrated with multiple local vibration absorbers, and the wide frequency damping effect is realized. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A flowchart of the design method of the damping boring tool in an exemplary embodiment.

[0041] Figure 2 A flowchart of the design method of the damping boring tool in an exemplary embodiment.

[0042] Figure 3 A flowchart of the design method of the damping boring tool in an exemplary embodiment.

[0043] Figure 4 A structural schematic diagram of the boring tool in an exemplary embodiment.

[0044] Figure 5 A structural schematic diagram of the boring tool in an exemplary embodiment.

[0045] Figure 6 A schematic diagram of the radial direction of the cutting edge in an exemplary embodiment.

[0046] Figure 7 A schematic diagram of the radial direction of the cutting edge in an exemplary embodiment.

[0047] Figure 8 A schematic diagram of the local part of the cutting edge in an exemplary embodiment.

[0048] Figure 9 A structural schematic diagram of the radial rod in an exemplary embodiment.

[0049] Figure 10 A C-C cross-sectional schematic diagram as shown. Figure 9

[0050] Figure 11 ​A simplified model diagram of a radial arm in an exemplary embodiment.

[0051] Figure 12 A simplified model diagram of a radial arm in an exemplary embodiment.

[0052] Reference Signs:

[0053] 1, blade; 2, radial arm; 21, polygonal structure; 211, rectangular plane; 3, handle; 31, clamping flat. DETAILED DESCRIPTION

[0054] In order to make the above objectives, features and advantages of the present application more clear and easily understood, the specific embodiments of the present application will be described in detail below with the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different ways from those described herein without departing from the scope of the present application, and those skilled in the art can make similar improvements without violating the spirit of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0055] In the description of the present application, it should be understood that if there are terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0056] In addition, if the terms "first", "second" appear, these terms are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features referred to. Therefore, the features limited by "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "a plurality of" appears, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0057] In the present application, unless specifically defined and limited otherwise, if there is a description of "mounting", "connecting", "connecting", "fixing" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] In the present application, unless specifically defined and limited otherwise, if there is a description of "mounting", "connecting", "connecting", "fixing" and the like, these terms should be broadly understood. For example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0059] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on another element or there can be a middle element. If an element is considered to be "connected" to another element, it can be directly connected to another element or there can be a middle element. If present, the terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used in the present application are for illustrative purposes only and do not represent the only implementation.

[0060] The present disclosure provides a design method of a vibration reduction boring tool, as shown in Figures 4-10 The method comprises the following steps:

[0061] S100, determining the size and shape of the boring tool.

[0062] In step S100, as shown in Figures 4-10 The specific design structure and parameters of the vibration reduction boring tool, combined with the characteristics of the hard alloy micro-diameter tool, optimize the cutting edge geometric parameters, the size of the diameter rod and the tool holder structure, to achieve the vibration reduction effect and machining precision improvement in the cutting process.

[0063] As shown in Figures 4-10 The boring tool is a hard alloy integrally formed structure, which includes a cutting edge 1, a diameter rod 2 and a tool holder 3 along the axial direction, and the three are fixedly connected and can be formed by sintering or whole grinding.

[0064] The cutting edge 1 is located at the front end of the boring tool and is a cutting functional part. A multi-edge gradual angle design is adopted to reduce cutting force and disperse vibration energy.

[0065] The diameter rod 2 is a transition part connecting the cutting edge 1 and the tool handle 3, and the diameter size is ≤3mm. For example, the D1 of the diameter rod 2 is 2.3mm. The cutting vibration transmission is reduced by reducing the cross-sectional area of the diameter rod.

[0066] The tool handle 3 is located at the tail end of the boring tool and is used to be connected with the clamping device of the machine tool spindle. The end away from the diameter rod 2 is processed with a clamping flat bit 31, and the width can be set to 1.5mm-2mm. The flat bit is matched with the clamp to prevent the tool from rotating and slipping, and the clamping stability is improved.

[0067] The geometric parameters of the cutting edge 1 are optimized from the end surface (cross section along the axial direction) and the top view (cross section perpendicular to the axis).

[0068] For example, as shown in Figures 4-6 , the end surface view angle parameters.

[0069] Three sections of radial clearance angles are distributed along the radial direction of the cutting edge 1, which are the first radial clearance angle α1, the second radial clearance angle α2, and the third radial clearance angle α3. Among them, α1 is 25°-30°, further, α1 is 28°; α2 is 45°-50°, further, α2 is 48°; α3 is 60°-70°, further, α3 is 65°. The gradually changing clearance angle design can gradually weaken the contact friction between the clearance surface and the workpiece, reduce the cutting heat, and reduce the vibration source.

[0070] The widths of the clearance surfaces corresponding to the three sections of clearance angles are the first radial clearance surface width b1 and the second radial clearance surface width b2. Among them, b1 is 0.4mm-0.6mm, further, b1 is 0.5mm; b2 is 1.0mm-1.2mm, further, b2 is 1.1mm. The width of the clearance surface is controlled to balance the strength of the tool and the chip space.

[0071] The end surface rake angle γ1 is set to 2°-3°. The design of a small positive rake angle can avoid the collapse of the cutting edge caused by too sharp cutting edge, and reduce the cutting force fluctuation.

[0072] The edge height H satisfies H<D1 of the diameter rod 2, for example, H=2mm. By limiting the edge height, the overhanging amount of the cutting edge is reduced, the rigidity is improved, and the vibration is suppressed.

[0073] For example, as shown in Figure 4 , Figure 5 , Figures 8-10 , the top view angle parameters.

[0074] The three axial rake angles are distributed along the cutting edge 1, and are respectively a first axial rake angle α4, a second axial rake angle α5, and a third axial rake angle α6. The first axial rake angle α4 is 8°-12°, and further, α4 is 10°; the second axial rake angle α5 is 20°-30°, and further, α5 is 25°; and the third axial rake angle α6 is 50°-60°, and further, α6 is 55°. The gradual change design of the axial rake angle can guide the chip flow direction, reduce the adhesion of the chip to the rake face, and reduce the cutting vibration.

[0075] The first axial rake face width b3 is 0.2mm-0.4mm, and further, b3 is 0.3mm. The narrow rake face design reduces the contact area with the workpiece.

[0076] The boring cutter has a rotary diameter, which is the diameter of one revolution around the axis of the shank 3 at the maximum width of the cutter. The rotary diameter D2≤5mm, for example, the rotary diameter D2 is 4.9mm. By limiting the rotary diameter, the centrifugal vibration during cutting is reduced.

[0077] The maximum working width A=(D2-D1) / 2 controls the cutting width to disperse the cutting force.

[0078] The nose R1 of the cutting edge 1 is 0.08mm-0.1mm, and the transition round corner R2<0.15mm. The small round corner design can enhance the strength of the nose and avoid micro-chipping caused by cutting vibration.

[0079] The clearance rake angle γ2 is -5°--3°. The negative rake angle design stabilizes the cutting through the "wedge" effect and suppresses vibration transmission.

[0080] The boring cutter in the embodiment is made of cemented carbide material by powder metallurgy-sintering process. For example, tungsten carbide (WC) particles and cobalt (Co) binder are mixed in a predetermined mass ratio, and ball milled to a particle size of ≤1μm. The preliminary blank of the cutting edge 1, the diameter rod 2, and the shank 3 is pressed by a precision mold to ensure the size accuracy of the diameter D1=2.3mm and the rotary diameter D2=4.9mm of the diameter rod 2. Vacuum sintering is carried out at 1400℃-1500℃, and then the angles of the cutting edge 1 are precisely ground by a numerical control grinding machine to ensure that the angle error is ≤±0.5°.

[0081] The method in the embodiment effectively reduces cutting vibration and improves the surface quality of the machined surface by the small diameter rod design, the gradual change of the rake angle, and the negative rake angle clearance structure. The surface roughness Ra≤0.8μm.

[0082] In S110, a polygonal structure is designed for the diameter rod.

[0083] In step S110, the polygonal structure of the diameter rod is designed by referring to the following formula: Figures 4-10As shown, by setting the polygonal structure 21 on the radial rod 2, combined with the optimization of its geometric parameters, the broadband vibration reduction effect in the cutting process is achieved. The boring cutter in this embodiment is a passive vibration reduction structure, that is, it does not require external energy input or active control system, but only through its own geometric structure design to suppress vibration.

[0084] The polygonal structure 21 includes a plurality of rectangular planes 211, which are sequentially connected to form a closed polygon. By changing the vibration transmission path and energy distribution through its preset geometric shape, broadband vibration reduction is achieved. Each rectangular plane 211 has different side lengths and inclination angles, and the inclination angle is the circumferential angle of the radial rod 2, that is, the inclination angle of the rectangular plane 211 relative to the boring cutter axis. Among them, the inclination angle B ranges from 10° to 20°.

[0085] Each rectangular plane 211 is arranged in a spiral or stepped shape around the boring cutter axis, forming a continuous asymmetric cross-section structure. In this embodiment, a spiral arrangement is adopted, and through the synergistic effect of the spiral rise angle and the inclination angle B, the radial rod 2 forms a gradually changing stiffness distribution in the circumferential direction.

[0086] The diameter of the radial rod 2 is 2mm-3mm, and the design of the polygonal structure 21 needs to meet the following parameter constraints:

[0087] When the diameter of the radial rod 2 is 2mm-3mm, the number of sides of the radial cross-section is set to 10-14. Too few sides will result in excessive material removal, weakening the overall rigidity of the radial rod 2; too many sides will increase the difficulty of numerical control grinding or electric spark machining, and increase the manufacturing cost.

[0088] The radial width N of the polygonal structure 21 is 2.15mm-2.2mm, and the radial width of the polygonal structure 21 is the maximum distance between adjacent parallel sides.

[0089] The boring cutter will be excited by periodic cutting force during cutting, and when the excitation frequency is close to the natural frequency of the boring cutter system, resonance is easy to occur. This embodiment can achieve broadband vibration reduction through the design of the polygonal structure 21.

[0090] The spiral arrangement of the rectangular planes 211 changes the moment of inertia I of the cross-section of the radial rod 2 relative to different bending directions due to the existence of the inclination angle B. Specifically, the moment of inertia I1 around the long side direction of the rectangular plane 211 is greater than the moment of inertia I2 around the short side direction, and by adjusting the inclination angle B, the ratio of I1 and I2 can be changed, and the bending stiffness matching different direction vibration working conditions (such as radial vibration, axial vibration) can be designed. Based on this stiffness regulation, the radial rod 2 can dissipate vibration in different directions.

[0091] Each rectangular plane 211 can be regarded as an independent vibration absorber, and the differences in the side length and the inclination angle make the natural frequency of each vibration absorber dispersed. The polygonal structure 21 integrates vibration absorbers with different parameters, so that the boring tool system forms multiple vibration reduction frequency bands in the range of 100 Hz-500 Hz (typical cutting excitation frequency range), avoiding single frequency resonance. Through the integration of multiple vibration absorbers, the broadband effect of passive vibration reduction is achieved, without the need for external control, and the structure itself can work.

[0092] For example, in terms of vibration mode reconstruction. The variable inclination angle and side length destroy the axial symmetry of the shaft 2, so that the vibration mode of the boring tool changes from single bending vibration to "bending-torsional" coupled vibration, and the vibration amplitude is reduced through energy dispersion. Under the passive vibration reduction framework, this kind of vibration mode helps to convert vibration energy into heat energy or other forms of energy and dissipate it, thereby reducing the vibration transmitted to the cutting edge 1 and the workpiece.

[0093] The method in this embodiment effectively reduces cutting vibration through passive vibration reduction design, i.e., a small-diameter shaft design, a gradually changing back angle optimization, a negative rake angle avoidance structure, and a shaft 2 with a polygonal structure 21. Through the spiral design and parameter optimization of the polygonal structure 21, broadband vibration reduction of the shaft 2 is achieved, which is suitable for high-precision micro-hole machining and significantly improves the machining stability and surface quality of the boring tool.

[0094] In step S110, the polygonal structure is designed for the shaft, as shown in Figure 2 The method further includes the following steps:

[0095] S1101, using finite element analysis or modal analysis software, simulating the vibration characteristics of the polygonal structure under different parameters.

[0096] In step S1101, referring to Figures 4-10 The shaft 2 of the boring tool is designed as a polygonal structure 21. The initial parameters are set, and the number of sides, the inclination angle B, and the radial width of the polygonal structure 21 are preliminarily determined according to the diameter of the boring tool. Parameter optimization is performed, and the geometric parameters of the polygonal structure 21, such as the number of sides, the inclination angle B, the side length of the rectangular plane 211, and the arrangement, are adjusted according to the simulation results until the vibration reduction effect meets the target requirements.

[0097] First, the model is established and meshed. Based on the initial parameters such as the number of sides, the inclination angle, and the radial width, a three-dimensional polygonal structure model of the shaft 2 is established, the side length of the rectangular plane 211 is arranged in a spiral shape, and the spiral rise angle is designed in cooperation with the inclination angle B. In this embodiment, for example, the number of sides is 12, the inclination angle is 15°, and the radial width is 2.18 mm.

[0098] The tetrahedral unit is used for high-precision meshing of the model, and the mesh size is controlled at 0.05mm-0.1mm to ensure the calculation accuracy, and the number of units is about 50,000-80,000. The material of the radial rod 2 is set as hard alloy, the elastic modulus is 600GPa, the Poisson's ratio is 0.22, and the density p is 14,500kg / m³.

[0099] Secondly, the boundary conditions and excitation are set. The fixed connection of the radial rod 2 and the handle 3 is simulated, and the bottom end of the radial rod 2, i.e. the connection end with the handle 3, is set as a fixed constraint.

[0100] The periodic cutting force in the cutting process is simulated, and a sinusoidal excitation force is applied at the top end of the radial rod 2, i.e. the connection end with the blade 1, the frequency range covers the typical cutting excitation frequency, which is 100Hz-500Hz, and the amplitude of the force is set as 5N-20N, which is adjusted according to the actual cutting parameters.

[0101] S1102, according to the simulation results, adjusting the geometric parameters of the polygonal structure and determining the vibration reduction effect.

[0102] In step S1102, referring to Figures 4-10 , a three-dimensional model of the radial rod 2 is established by using finite element analysis or modal analysis software to simulate its vibration characteristics under different parameters. Among them, mainly including modal analysis and harmonic response analysis.

[0103] In the modal analysis, the first 6 natural frequencies and vibration modes of the radial rod 2 are calculated, and the order which overlaps with the cutting excitation frequency (100Hz-500Hz) is concerned. For example, the simulation results show that the polygonal structure 21 with 12 sides has the first three natural frequencies of 152Hz, 285Hz and 418Hz when B is 15°, which avoids the common cutting resonance frequency such as 200Hz-300Hz.

[0104] In the harmonic response analysis, the excitation frequency is scanned in the frequency range of 100Hz-500Hz, and the vibration amplitude of the top end of the radial rod 2 is extracted. The simulation results show that when the excitation frequency is 250Hz, the vibration amplitude of the equal-diameter radial rod in the related art is obviously larger than that of the polygonal structure 21, and the vibration reduction effect is significant.

[0105] If the simulation shows that a certain order of natural frequency overlaps with the cutting excitation frequency, and further causes resonance, the stiffness distribution of the polygonal structure 21 can be changed by increasing or decreasing the number of sides to shift the natural frequency and avoid the resonance region.

[0106] If the harmonic response analysis shows that the vibration amplitude is too high at a certain frequency, the inclination angle B can be adjusted to change the moment of inertia distribution of the rectangular plane 211 to enhance the suppression ability of vibration in a certain direction.

[0107] If the vibration mode shows that the energy is concentrated in several rectangular planes 211, the length of each rectangular plane 211 is adjusted to disperse the vibration energy to more planes.

[0108] The method in the embodiment is aimed at the design of the shank structure of the boring tool. Through simulation and parameter optimization of a finite element analysis or modal analysis software, the precise design of the passive damping shank structure is realized, the cutting vibration is effectively suppressed, and the precision and stability of micro-hole machining are improved.

[0109] In step S110, the shank is designed in a polygonal structure, as shown in Figure 3 , and further comprising the following steps:

[0110] S1103, define the initial length and inclination angle of each rectangular plane as design variables.

[0111] In step S1103, referring to Figures 4-10 , the design variables are defined, such as the initial length and inclination angle of the rectangular plane 211.

[0112] In the design of the polygonal structure 21 of the shank 2, the initial length of each rectangular plane 211 is denoted as L i , i = 1, 2,..., n, n is the number of sides, and the inclination angle is denoted as B i , i = 1, 2,..., n.

[0113] The design of the length L i . According to the diameter size D1 = 2mm-3mm of the shank 2, the embodiment takes 2.3mm, and the radial width of the polygonal structure 21 is 2.15mm-2.2mm, the embodiment takes 2.18mm, the initial length is set to 1.0mm-1.5mm, then in the 12-sided polygonal structure 21, L1=1.2mm, L2=1.1mm,..., L 12 =1.3mm, to ensure that the length difference of adjacent rectangular planes 211 forms a stiffness gradient. It should be noted that the lengths of adjacent rectangular planes 211 can also be set to be the same.

[0114] The design of the inclination angle B i . The circumferential inclination angle of the rectangular plane 211 relative to the boring tool axis is set to 10°-20°, and the initial value in the embodiment is 15°, and the inclination angles B i of the rectangular planes 211 can be the same or different, for example, when arranged in a spiral, B i increases or decreases along the circumference to form a spiral angle.

[0115] The initial values of the design variables are determined based on empirical formulas or finite element analysis, for example, the length L iThe radial width requirement of the polygonal structure 21 (such as 2.18 mm) must be met, and the inclination angle B i Overlap with the natural frequency of the radial rod 2 must be avoided (such as avoiding the typical cutting resonance region of 200-300 Hz).

[0116] S1104, using a parameterized design method, generating polygonal structure models under different parameter combinations.

[0117] In step S1104, referring to Figures 4-10 As shown, using a parameterized design method, through the variable driving function or programming API (such as Python combined with SolidWorks API) of CAD software (or SolidWorks, CATIA, etc.), polygonal structure 21 models with different L i and B i combinations are generated.

[0118] S1105, simulating the vibration characteristics of each polygonal structure model, recording its natural frequency, mode shape and damping ratio.

[0119] In step S1105, referring to Figures 4-10 , the vibration characteristics of each polygonal structure 21 model generated above are simulated through finite element analysis or modal analysis software, and the natural frequency, mode shape and damping ratio are recorded.

[0120] Modal analysis is performed on free vibration, and the first 6 order natural frequencies (low order natural frequencies have greater impact on cutting vibration) and mode shapes (such as bending vibration, torsional vibration, bending-torsional coupled vibration) of each model are calculated.

[0121] For example, model 1 (design parameters: L = 1.2 mm, B = 15°), the first 3 order natural frequencies are 152 Hz, 285 Hz, 418 Hz, and the mode shapes are "bending vibration at the top of the radial rod" (set as the first order), "torsional vibration in the middle of the radial rod" (set as the second order), and "bending-torsional coupled vibration of the entire radial rod" (set as the third order).

[0122] Model 2 (design parameters: L = 1.1 mm, B = 18°), the first 3 order natural frequencies are 165 Hz, 302 Hz, 440 Hz, and the mode shapes are similar to those of model 1, but the second order natural frequency 302 Hz avoids the typical cutting resonance region of 200-300 Hz.

[0123] Model 3 (design parameters: L = 1.3 mm, B = 12°), the first 3 order natural frequencies are 145 Hz, 270 Hz, 400 Hz, and the second order natural frequency 270 Hz is at the edge of the resonance region, which is prone to resonance.

[0124] Harmonic response analysis, i.e. damping ratio calculation. Apply sinusoidal excitation force (amplitude 5N-20N, simulating cutting force) in the frequency range of 100Hz-500Hz, calculate the vibration amplitude (acceleration) of each model, and calculate the damping ratio ζ (reflecting the energy dissipation ability of the structure) by the half-power bandwidth method.

[0125] ζ = Δf / 2f0

[0126] where Δf is the half-power bandwidth at resonance frequency f0 (the frequency range when the amplitude drops to 1 / 2 of the peak value), and f0 is the resonance frequency (i.e. natural frequency).

[0127] For example, the vibration amplitude of model 2 at 302Hz (2nd order natural frequency) is 5m / s 2 , the half-power bandwidth Δf = 15Hz, and the damping ratio ζ = 15 / (2x302) ≈ 0.0248. The damping ratio of the equal-diameter rod (diameter 2.3mm) in the related art is about 0.01, indicating that the energy dissipation ability of model 2 is stronger and the damping effect is better.

[0128] Based on the simulation results described above, model 2 (L i =1.1mm, Bi=18°) is selected as the optimal design, and its vibration characteristics meet the following requirements: the first three natural frequencies (165Hz, 302Hz, 440Hz) all avoid the typical cutting resonance region of 200Hz-300Hz. The 2nd order mode shape is "bending-torsional coupled vibration", and the energy dispersion effect is good. The damping ratio ζ = 0.025, which is 150% higher than that of the equal-diameter rod in the related art, and the energy dissipation ability is strong.

[0129] The method in this embodiment realizes the passive damping precise design of the polygonal structure 21 of the rod 2 by defining the design variables (edge length L i , inclination angle B i ), parameterizing the model, and simulating the vibration characteristics (modal analysis and harmonic response analysis).

[0130] In S120, the edge length, the length of each edge, the inclination angle, and the grinding method of the polygonal structure are adjusted to optimize the spring stiffness and damping characteristics of the tuned mass damper.

[0131] In step S120, referring to Figures 4-12 , the boring tool rod 2 is designed as a polygonal structure 21, and the optimization process of the polygonal structure 21 as a tuned mass damper is based on a global-local system coupling model.

[0132] For example, the main vibration system (m1, k1, c1) is set up, and the boring bar 2 is simplified into a cantilever beam model (one end is fixed to the tool holder 3, and the other end is freely connected to the cutting edge 1), representing the main vibration characteristics of the boring bar. Among them, the mass block m1 simulates the main mass distribution of the boring bar 2; the spring k1 reflects the overall stiffness of the boring bar 2; and the damper c1 embodies the material internal damping of the main system.

[0133] A local vibration system (m2, k2, c2) is defined. Each rectangular plane 211 of the polygonal structure 21 is simplified as a tuned mass damper attached to the main system and connected to the main system through the geometric center point M. Here, the mass block m2 represents the mass of a single rectangular plane 211 (material is the same as rod 2, mass is equal to side length L). i Positive correlation); spring k2 reflects the local stiffness of rectangular plane 211 (derived from side length L). i and tilt angle B i (Decision); Damper c2 reflects the energy dissipation capacity of the local structure (related to surface roughness and stress distribution).

[0134] By adjusting the number of side lengths n and the length L of each side of polygon structure 21 i Inclination angle B i The grinding method allows the natural frequencies of the local system (m2,k2,c2) and the main system (m1,k1,c1) to be tuned (f2≈f1), and the damping ratio ζ2 is maximized, thereby reducing the vibration amplitude of the main system through energy dissipation.

[0135] Among them, the spring stiffness k2 is the core parameter of the tuned mass damper, which is determined by the side length L of the rectangular plane 211. i and tilt angle B i The factors are jointly determined. Therefore, the optimization method for spring stiffness k2 can be achieved by adjusting the side length Li and tilt angle Bi of the rectangular plane 211.

[0136] For example, the tilt angle B of rectangular plane 211 i The moment of inertia I of the cross section relative to different bending directions is changed. For an inclined rectangular cross section, the moment of inertia I1 about its long side is greater than I2 about its short side, and the bending stiffness k2 is proportional to I. For example, when B i When the angle is increased from 15° to 18°, the moment of inertia I1 of the rectangular plane 211 about the radial direction (perpendicular to the boring bar axis) increases by 20%, and the moment of inertia I2 about the axial direction (parallel to the boring bar axis) decreases by 15%. This allows for a higher k2 to be designed for radial vibration (typical cutting excitation direction), thereby enhancing the ability to suppress vibration in this direction.

[0137] Therefore, by adjusting B of each rectangular plane 211 i (e.g., B when arranged in a spiral) iThe polygonal structure 21 forms stiffness gradients in the radial (k2-r) and axial (k2-a) directions, matching vibration working conditions in different directions (such as radial cutting force, axial cutting force).

[0138] For example, there is a positive correlation between the side length and the stiffness, so that the side length L i directly affects k2. Shorter L i may increase k2, which is suitable for suppressing high-frequency vibration; longer L i may reduce k2, which is suitable for suppressing low-frequency vibration. Exemplarily, for a boring cutter with a radial rod 2 diameter D1=2.3mm, a 12-sided structure is selected, with a side length L i arranged in an alternating "short-long-short" manner (such as L1=1.1mm, L2=1.3mm, …, L 12 =1.2mm) or arranged in order according to the same side length, so that k2 forms multiple tuning frequencies in the range of 100Hz-500Hz, covering typical cutting excitation frequencies.

[0139] For example, the number of side lengths n affects k2, and the number of side lengths corresponds to the number of absorbers. The number of side lengths n determines the number of tuned mass dampers integrated by the polygonal structure 21, and n rectangular planes 211 correspond to n local systems. Too few sides will reduce the number of absorbers and reduce the broadband damping effect; too many sides will increase the processing difficulty and cause the stiffness of the main system to be lost. Exemplarily, when n increases from 12 sides to 14 sides, the number of absorbers increases by 16.7%, the broadband damping bandwidth expands from 150Hz to 200Hz (covering 100Hz-500Hz), but the stiffness of the main system decreases by 5% (which needs to be compensated by adjusting L i ).

[0140] The damping characteristic c2 is a key parameter of the tuned mass damper, mainly from the internal structural damping and surface friction damping of the material, and is optimized by grinding and stress distribution of the polygonal structure. Among them, the optimization of the damping characteristic c2 can be adjusted by grinding and parameter design of the polygonal structure 21.

[0141] For example, the influence of grinding method on c2. Firstly, different grinding methods such as precision grinding and electrical discharge grinding can be used to change the surface roughness of the rectangular plane 211, thereby affecting the surface friction damping. For example, precision grinding can reduce surface friction and is suitable for high-frequency vibration suppression requiring low damping; electrical discharge grinding can increase the surface micro-convex body and improve the surface friction damping, which is suitable for low-frequency vibration suppression requiring high damping. Secondly, residual stress can be introduced. By ultrasonic vibration assisted grinding, residual compressive stress is introduced on the surface of the rectangular plane 211, changing the stress distribution inside the material and promoting energy dissipation. For example, ultrasonic vibration assisted grinding can increase the residual compressive stress of the rectangular plane 211 by 30%, and the damping ratio ζ2 can be increased from 0.02 to 0.025, which is 25% higher than the related art grinding.

[0142] For example, the influence of the polygonal structure 21 on c2. Firstly, local stress concentration. The inclined rectangular plane 211 of the polygonal structure 21 generates a complex local stress field when vibrating, such as stress concentration at the inclined edge, which promotes energy dissipation inside the material. Secondly, multiple damping paths. The multiple rectangular planes 211 of the polygonal structure 21 form multiple damping paths, and the vibration energy is dissipated through the friction and deformation of different planes, avoiding energy saturation in a single path.

[0143] The method of the embodiment designs the polygonal structure 21 of the radial rod 2 as a passive damping structure integrated with multiple local vibration absorbers through the tuned mass damper model, adjusts the number of side lengths, the length of each side, and the inclination angle to optimize the spring stiffness k2, and adjusts the grinding method to optimize the damping characteristics c2, thereby achieving a wide-frequency damping effect.

[0144] S130, verifying the damping effect of the mass-spring-damper system composed of the polygonal structure and the boring tool.

[0145] In step S130, referring to FIG. 8, the damping effect of the coupled system composed of the polygonal structure 21 (as a tuned mass damper) and the boring tool in actual cutting is confirmed by the control variable method. Figures 4-12

[0146] Multiple boring tools can be made to serve as samples. The parameters of the polygonal structure 21, such as the number of side lengths n, the length of each side L i , the inclination angle B i , and the grinding method, are different, and the remaining conditions such as the material, the structure of the tool shank 3, the parameters of the cutting edge 1, and the machining equipment are completely consistent. Under the same machining conditions such as cutting speed, feed rate, cutting depth, and workpiece material, boring tests are performed to ensure the comparability of the results. The vibration amplitude (acceleration) and the machining surface quality (roughness Ra) are used as core indicators to evaluate the damping effect.

[0147] ​In implementation, according to the optimization result of step S120, 3 groups of boring tool samples with different polygon structure parameters are manufactured (for example, 3 in each group, a total of 9). Among them, the first group of samples is used to verify the effect of constant tilt angle; the second group of samples is used to verify the synergistic effect of spiral increasing tilt angle and ultrasonic grinding; the third group of samples is used to verify the influence of reducing the number of sides.

[0148] Then, the aluminum alloy workpiece is bored on the vertical machining center.

[0149] The vibration amplitude is measured. For example, a three-axis acceleration sensor is installed at the connection between the boring tool handle 3 and the main shaft to monitor the vibration acceleration in the X (radial), Y (axial), and Z (tangential) directions in real time. The vibration signal during cutting is recorded by a data acquisition system, and the peak vibration amplitude is extracted as an evaluation index.

[0150] The machining surface quality is detected. For example, a surface roughness meter is used to randomly select 5 measurement points on the boring surface of the workpiece, and the arithmetic average roughness is calculated. Avoid the tool cutting / in cutting area to ensure that the measurement area is a stable cutting area.

[0151] The vibration reduction effect is quantitatively evaluated, and the monitoring data is statistically analyzed to obtain the quantitative results of the vibration reduction effect of each sample. The average vibration amplitude of each group of samples (3) is calculated to eliminate accidental errors of a single tool. The vibration amplitude of the equal-diameter rod boring tool in the related art is taken as the benchmark to calculate the vibration reduction rate. The average roughness of each group of samples is calculated as a surface quality index.

[0152] Finally, the above parameters are compared with the preset standard to determine whether the boring tool reaches the vibration reduction target.

[0153] In this step, when verifying the vibration reduction effect, each design parameter can also be recorded to facilitate subsequent iteration and optimization of the boring tool parameters. According to the verification result, the parameters of the polygon structure 21 are iteratively optimized until the preset target is reached.

[0154] First, different design data and verification results are obtained by adjusting the parameters in different directions. For example, through the first group of samples, spiral increasing and ultrasonic grinding are performed, and the side length is fine-tuned to reduce the vibration amplitude. Through the second group of samples, the grinding method is changed from precision grinding to ultrasonic vibration assisted electric spark grinding to enhance the damping characteristics. Through the third group of samples, the number of sides n is increased, and the spiral increasing is adjusted to increase the number of vibration absorbers and the stiffness matching.

[0155] Secondly, the iterative verification is corresponded to the database. The optimized boring tool samples are repeatedly tested in step S130 to confirm the vibration amplitude and roughness. The design parameters and verification results of each optimization are recorded to form a design optimization database, which contains at least 5 groups of effective data.

[0156] The method of the embodiment confirms the vibration reduction effect of the polygonal structure 21 as a tuned mass damper through a closed-loop verification process of sample making, standardized testing, quantitative evaluation, and iterative optimization. The final optimized parameters enable the boring tool to achieve the preset targets of vibration amplitude ≤ 5 m / s² and surface roughness Ra ≤ 0.8 μm in aluminum alloy cutting, and are suitable for high-precision micro-hole machining scenarios.

[0157] Any combination of the technical features of the above-described embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the description.

[0158] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent application scope. It should be noted that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method for designing a vibration-damping boring tool, characterized in that, include: The dimensions and shape of the boring bar are determined; wherein the boring bar includes a shank. The radial rod is designed with a polygonal structure, which includes multiple rectangular planes connected in sequence to form a closed polygon; wherein each rectangular plane has a different side length and tilt angle. By adjusting the number of sides, length of each side, tilt angle, and grinding method of the polygonal structure, its spring stiffness and damping characteristics as a tuned mass damper are optimized. Verify the vibration reduction effect of the mass-spring-damping system formed by the polygonal structure and the boring tool.

2. The design method for a vibration-damping boring tool according to claim 1, characterized in that, The design of the polygonal structure in the radial rod includes: The vibration characteristics of the polygonal structure under different parameters were simulated using finite element analysis or modal analysis software. Based on the simulation results, the geometric parameters of the polygonal structure were adjusted, and the vibration reduction effect was determined.

3. The design method for a vibration-damping boring tool according to claim 2, characterized in that, The design of the polygonal structure in the radial rod includes: Define the initial side length and tilt angle of each rectangular plane as design variables; Using parametric design methods, polygonal structure models with different parameter combinations are generated; Vibration characteristics were simulated for each polygonal structure model, and its natural frequency, mode shape, and damping ratio were recorded.

4. The design method for a vibration-damping boring tool according to claim 1, characterized in that, The diameter of the caliper is less than or equal to 3 mm, and the rotation diameter of the boring tool is less than or equal to 5 mm.

5. The design method for a vibration-damping boring tool according to claim 4, characterized in that, When the diameter of the radial rod is 2mm-3mm, the number of side lengths of the radial section of the radial rod is 10-14, the radial width of the polygonal structure is 2.15mm-2.2mm, and the radial width of the polygonal structure is the maximum distance between adjacent parallel sides; The tilt angle is 10°-20°, and the tilt angle is the circumferential angle of the diameter rod.

6. The design method for a vibration-damping boring tool according to claim 1, characterized in that, Each of the rectangular planes is arranged in a spiral or stepped shape around the axis of the boring tool; The vibration-damping boring tool is a passive vibration damping type.

7. The design method for a vibration-damping boring tool according to claim 6, characterized in that, The optimization of its spring stiffness and damping characteristics as a tuned mass damper includes: By changing the side length and tilt angle of each rectangular plane in the polygonal structure, its moment of inertia relative to different bending directions is adjusted; Different grinding methods are used to process the edges of the polygonal structure to change its surface roughness and stress distribution, thereby affecting its damping characteristics.

8. The design method for a vibration-damping boring tool according to claim 1, characterized in that, The verification of the vibration reduction effect of the mass-spring-damping system jointly formed by the polygonal structure and the boring tool includes: Prepare boring bar samples with different polygonal structure parameters, ensuring that all conditions are consistent except for the polygonal structure. Under the same processing conditions, boring tests were performed on each sample; Measure and compare the vibration amplitude and surface quality of each sample during processing to evaluate the vibration reduction effect.

9. The design method for a vibration-damping boring tool according to claim 8, characterized in that, The evaluation of vibration reduction effect includes: Vibration sensors and surface quality detectors are used to monitor and record vibration data and surface quality during the processing in real time. Statistical analysis of the monitoring data yielded a quantitative evaluation of the vibration reduction effect of each sample. The quantitative assessment results are compared with the preset standards to determine whether the vibration reduction target has been achieved.

10. The design method for a vibration-damping boring tool according to claim 1, characterized in that, Also includes: Based on the verification results, the design parameters of the polygonal structure are iteratively optimized until the preset vibration reduction effect and processing quality requirements are achieved.

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