Ultrasonic micropore machining method

Abstract

The invention relates to the technical field of micropore machining, in particular to an ultrasonic micropore machining method which comprises the steps that the initial amplitude A of an ultrasonic vibrator is obtained, and based on the initial amplitude A, kinetic energy Umn generated when abrasive particles impact the surface of a workpiece is determined; acquiring or calculating critical kinetic energy Uc of brittle fracture of the workpiece material to be processed; and based on the kinetic energy Umn generated when the abrasive particles impact the surface of the workpiece and the critical kinetic energy Uc generated when the to-be-machined workpiece material generates brittle fracture, the minimum amplitude value A < min > of the ultrasonic vibrator is determined. And by calculating and optimizing the machining parameters, the technical effect of improving the machining quality of the micropores is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-hole machining, in particular to an ultrasonic micro-hole machining method. BACKGROUND

[0002] Non-contact ultrasonic micro-hole machining mainly relies on the comprehensive results of mechanical impact, grinding and polishing effect and cavitation effect of abrasive particles on the workpiece surface under the action of ultrasonic waves. When it exceeds the critical value of brittle fracture, the material is removed.

[0003] In the prior art, due to the influence of various factors such as the properties of the material itself, abrasive particles, tool head shape, etc., the stability of the machining quality is difficult to guarantee, and the machining parameters are difficult to adjust, resulting in low micro-hole machining quality.

[0004] Therefore, the technical problem of the prior art is that the micro-hole machining quality is low. SUMMARY

[0005] The present application provides an ultrasonic micro-hole machining method, which optimizes the machining parameters through calculation, and achieves the technical effect of improving the micro-hole machining quality.

[0006] The ultrasonic micro-hole machining method provided by the present application adopts the following technical scheme:

[0007] An ultrasonic micro-hole machining method comprises:

[0008] Obtaining an initial amplitude A of an ultrasonic vibrator, and determining the kinetic energy U of abrasive particles impacting a workpiece surface based on the initial amplitude A mn ;

[0009] Obtaining or calculating the critical kinetic energy U c of brittle fracture of the material of the workpiece to be machined;

[0010] Based on the kinetic energy U mn of abrasive particles impacting a workpiece surface and the critical kinetic energy U c of brittle fracture of the material of the workpiece to be machined, determining the minimum amplitude A min of the ultrasonic vibrator.

[0011] As a preferred embodiment, the determination of the kinetic energy U mn of abrasive particles impacting a workpiece surface based on the initial amplitude A comprises:

[0012] Based on the initial amplitude A and the output end vibration speed v f of the ultrasonic vibrator, determining the speed v m of abrasive particles after acceleration;

[0013] Based on the output end vibration speed v f of the ultrasonic vibrator and the speed v m of abrasive particles after acceleration, determining the resultant speed of abrasive particles

[0014] Based on abrasive particle synthesis velocity Determine the kinetic energy U of abrasive impact on the workpiece surface mn .

[0015] Preferably, the initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer are used as the basis for the measurement. f Determine the velocity v of the abrasive particles after acceleration. m include:

[0016] Based on the initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer f Density ρ of the processing solution l The speed of ultrasound propagation in a liquid, c, is used to determine the air pressure P generated at the output end of the ultrasonic transducer. The air pressure P generated at the output end of the ultrasonic transducer is:

[0017] P = ρ l ·c·v f

[0018] Based on the air pressure P generated at the output end of the ultrasonic transducer, atmospheric pressure P0, and saturated vapor pressure P inside the cavitation bubble. in and the density ρ of the processing solution l Determine the velocity v of the abrasive particles after acceleration. m The velocity v of the abrasive particles after acceleration m for:

[0019]

[0020] Preferably, the method based on the vibration velocity v at the output end of the ultrasonic transducer f and the velocity v after abrasive acceleration m Determine the abrasive particle synthesis rate include:

[0021] Based on the vibration velocity v at the output end of the ultrasonic transducer f The velocity v of the abrasive particles after acceleration m And the cycle time T, to determine the abrasive particle synthesis rate. The abrasive particle synthesis rate for:

[0022]

[0023] Preferably, the abrasive particle synthesis rate-based Determine the kinetic energy U of abrasive impact on the workpiece surface mn include:

[0024] Based on abrasive particle synthesis velocity The energy conversion efficiency η, abrasive grain radius R, and abrasive grain density ρ are used to determine the kinetic energy U of the abrasive grains impacting the workpiece surface. mn The kinetic energy U of the abrasive particles impacting the workpiece surfacemn for:

[0025]

[0026] Preferably, the kinetic energy U based on abrasive impact on the workpiece surface mn The critical kinetic energy U that causes brittle fracture in the workpiece material c Determine the minimum amplitude A of the ultrasonic transducer. min include:

[0027] The kinetic energy U that causes abrasive grains to impact the workpiece surface mn The kinetic energy U is greater than the critical kinetic energy U required for brittle fracture of the workpiece material. c Determine the minimum amplitude A of the ultrasonic transducer. min .

[0028] As a preferred option, when determining the minimum amplitude A of the ultrasonic transducer min This also includes:

[0029] Based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the tool feed rate v z ;

[0030] Real-time machining force feedback values ​​are obtained by a force sensor located beneath the workpiece, and the feed rate v is adjusted based on these force feedback values. z .

[0031] Preferably, the kinetic energy U based on abrasive impact on the workpiece surface mn Determine the tool feed rate v z include:

[0032] Based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the volume of material removed from the workpiece, V, under the impact of a single abrasive grain. C ;

[0033] Workpiece material removal volume V based on single abrasive grain impact C Determine the tool feed rate v z .

[0034] Preferably, the kinetic energy U based on abrasive impact on the workpiece surface mn Determine the volume of material removed from the workpiece, V, under the impact of a single abrasive grain. C include:

[0035] Based on the kinetic energy U of abrasive impact on the workpiece surface mn 1. Elastic modulus E2 of the workpiece; 2. Ultimate fracture strength K of the workpiece material IC And the hardness H of the workpiece material, to determine the volume of material removed V from the workpiece under the impact of a single abrasive grain. CThe volume of workpiece material removed V under the impact of a single abrasive grain C for:

[0036]

[0037] Where α is the monopole scattering coefficient of the abrasive grain;

[0038] β is the dipole scattering coefficient of the abrasive grain.

[0039] Preferably, the workpiece material removal volume V based on the impact of a single abrasive grain C Determine the tool feed rate v z include:

[0040] Based on the ultrasonic transducer frequency f, abrasive concentration c', and minimum ultrasonic transducer amplitude A min Density ρ of the processing solution l Based on the abrasive particle density ρ and the machining hole area S, the number of particles N impacting per unit time is determined. The number of particles N impacting per unit time is:

[0041]

[0042] Based on the number of impacting particles N per unit time and the volume of material removed from the workpiece under the impact of a single abrasive grain V. C The ultrasonic transducer frequency f and the machined hole area S are used to determine the tool feed rate v. z The tool feed rate v z for:

[0043]

[0044] In summary, this application includes at least one of the following beneficial technical effects:

[0045] By calculating the matching relationship between the impact kinetic energy of abrasive particles and the critical fracture kinetic energy of the material, the minimum amplitude of the oscillator is accurately determined, ensuring that the abrasive particles can effectively remove the material while avoiding processing defects caused by excessive impact force. This solves the problem of poor processing quality stability in the existing technology and achieves the technical effect of improving the processing quality of micro-holes. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the ultrasonic transducer amplitude calculation process of the processing method described in this application;

[0047] Figure 2 This is a schematic diagram of the sound pressure distribution generated at the output end of the ultrasonic transducer described in this application in the liquid domain;

[0048] Figure 3 This is a schematic diagram of the feedback adjustment process of the processing method described in this application. Detailed Implementation

[0049] The serial numbers assigned to components in this document, such as "first" and "second," are used solely to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages). It should be understood that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are used solely for the convenience of describing this application and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0050] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0051] This application provides an ultrasonic micro-hole processing method, which improves the quality of micro-hole processing by calculating and optimizing processing parameters.

[0052] To better understand the above technical solutions, a detailed description of the technical solutions will be provided below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0053] Existing non-contact ultrasonic micro-hole machining technology suffers from core contradictions and specific defects, making it difficult to balance machining quality and efficiency. Machining relies on abrasive impact force to remove material, but the magnitude of the force is difficult to control. If the force is too small, the machining speed is extremely slow, or even impossible to remove material. If the force is too large, it will cause the workpiece crack to extend beyond the limit, resulting in chipping defects and seriously affecting the machining quality (especially for hard and brittle materials such as diamond and sapphire). The output amplitude of ultrasonic components, abrasive materials (such as diamond and silicon carbide), and particle size required for machining different materials (such as superhard materials and ordinary hard and brittle materials) vary greatly, and there is a lack of unified quantitative adaptation standards. It requires adjustment based on the operator's experience, which requires a high level of operational skills and is prone to machining failure due to parameter mismatch. The lack of real-time monitoring and adjustment mechanisms throughout the machining process makes it impossible to detect changes in abrasive concentration (such as the slowing of abrasive circulation and the addition of debris due to increased drilling depth) and mismatch between feed rate and material removal rate, ultimately leading to large fluctuations in machining quality and making it difficult to guarantee consistency.

[0054] Therefore, this application proposes a method for quantitatively optimizing processing parameters. By calculating the matching relationship between the impact kinetic energy of abrasive particles and the critical fracture kinetic energy of the material, the minimum amplitude of the oscillator is accurately determined, ensuring that the abrasive particles can effectively remove the material while avoiding processing defects caused by excessive impact force.

[0055] An ultrasonic micropore fabrication method, such as Figure 1 As shown, it includes: obtaining the initial amplitude A of the ultrasonic transducer, and determining the kinetic energy U of the abrasive impact on the workpiece surface based on the initial amplitude A. mn ; Obtain or calculate the critical kinetic energy U at which the workpiece material undergoes brittle fracture. c ; Based on the kinetic energy U of abrasive impact on the workpiece surface mn The critical kinetic energy U that causes brittle fracture in the workpiece material c Determine the minimum amplitude A of the ultrasonic transducer. min .

[0056] Among them, the kinetic energy U of the abrasive grains impacting the workpiece surface is determined based on the initial amplitude A. mn Including: based on the initial amplitude A, the vibration velocity v at the output end of the ultrasonic transducer f Determine the velocity v of the abrasive particles after acceleration. m Based on the vibration velocity v at the output end of the ultrasonic transducer f and the velocity v after abrasive acceleration m Determine the abrasive particle synthesis rate Based on abrasive particle synthesis velocity Determine the kinetic energy U of abrasive impact on the workpiece surface mn .

[0057] Specifically, based on the initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer... f Determine the velocity v of the abrasive particles after acceleration.m Based on the vibration velocity v at the output end of the ultrasonic transducer f and the velocity v after abrasive acceleration m include:

[0058] Based on the initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer f Density ρ of the processing solution l The speed of ultrasound propagation in a liquid, c, determines the air pressure P generated at the output end of the ultrasonic transducer. The air pressure P generated at the output end of the ultrasonic transducer is:

[0059] P = ρ l ·c·v f

[0060] Based on the air pressure P generated at the output end of the ultrasonic transducer, atmospheric pressure P0, and saturated vapor pressure P inside the cavitation bubble. in and the density ρ of the processing solution l Determine the velocity v of the abrasive particles after acceleration. m The velocity v of the abrasive particles after acceleration m for:

[0061]

[0062] More specifically, the abrasive material and size are determined based on the ultrasonic processing requirements. For example, diamond abrasive is used when processing superhard materials such as diamond and sapphire, while silicon carbide can be used when processing hard and brittle materials with low hardness. The abrasive grain size is selected according to the required processing dimensional accuracy; smaller abrasive grains correspond to higher accuracy requirements. Under the above processing requirements, the abrasive radius R and abrasive grain density ρ are determined. The sound pressure distribution generated at the output end of the ultrasonic transducer with initial amplitude A in the liquid domain is as follows: Figure 2 As shown, the sound pressure generated at the output end of the ultrasonic transducer:

[0063] P = ρ l ·c·v f

[0064] Among them, v f ρ is the vibration velocity at the output end of the ultrasonic transducer. l The density of the processing solution is given by c, and the speed of ultrasound propagation in the liquid is given by c.

[0065] v f =2πfA cos(2πft)

[0066] That is, P = ρ l cv f =ρ l c·2πfA cos(2πft)

[0067] Where f is the frequency of the ultrasonic transducer and t is the time; in one embodiment, a multi-frequency ultrasonic tool can be used, and the frequency can be switched according to the processing requirements. High frequency is used for materials with higher fracture energy, and low frequency is used for ordinary materials.

[0068] Furthermore, the velocity of the abrasive particles in the ultrasonic field after being accelerated by the microjets generated instantaneously by the collapse of cavitation bubbles (i.e., the velocity v of the accelerated abrasive particles) is... m In a liquid-domain ultrasonic machining environment, the velocity v of an abrasive grain after being impacted by a high-speed microjet generated by the rupture of cavitation bubbles is called the additional velocity v of the abrasive grain. m It is the abrasive particle synthesis velocity (the vibration velocity v at the output end of the ultrasonic transducer). f With the velocity v after abrasive grain acceleration m The vector sum is an important component that directly determines the magnitude of the impact force when abrasive grains strike the workpiece surface.

[0069] The abrasive particles in the ultrasonic field are accelerated to their velocity (i.e., the velocity v of the accelerated abrasive particles) by the microjets generated instantaneously by the collapse of cavitation bubbles. m )for:

[0070]

[0071] Where P is the air pressure generated at the output end of the ultrasonic transducer, P0 is the atmospheric pressure, and P in ρ is the saturated vapor pressure inside the cavitation bubble. l Density of the processing solution.

[0072] Furthermore, based on the vibration velocity v at the output end of the ultrasonic transducer f and the velocity v after abrasive acceleration m Determining the abrasive particle synthesis velocity v includes: based on the vibration velocity v at the output end of the ultrasonic transducer. f The velocity v of the abrasive particles after acceleration m And the cycle time T, to determine the abrasive particle synthesis rate. Abrasive synthesis speed for:

[0073]

[0074] In other words, the velocity of the abrasive particles changes continuously with the ultrasonic vibration period (the output velocity v of the ultrasonic transducer). f With the velocity v after abrasive grain acceleration m Both are affected by periodicity), and instantaneous velocity cannot reflect the stabilizing effect of continuous impact on the workpiece; because the vibration of the ultrasonic transducer is periodic (period T), the combined velocity of the abrasive particles (the vibration velocity v at the output end of the ultrasonic transducer) is also affected by periodicity. f With the velocity v after abrasive grain acceleration mThe vector sum of the velocity vectors also exhibits periodicity. Therefore, to obtain the effective average velocity of a workpiece impacted by abrasive particles, it is necessary to integrate and average the velocity vector magnitude over one period, i.e.:

[0075]

[0076] The integration process eliminates the interference of instantaneous velocity fluctuations, resulting in the composite velocity of the abrasive particles. This is the effective velocity of abrasive particles continuously and stably impacting the workpiece, providing a reliable benchmark for subsequent kinetic energy calculations. Through periodic integral averaging, the problem of time-varying velocity under periodic vibration is solved, making the effective impact velocity of the abrasive particles quantifiable. This ensures the stability and accuracy of subsequent kinetic energy calculations, avoiding energy estimation errors caused by instantaneous velocity fluctuations. In other words, the composite velocity of the abrasive particles... The output velocity v of the ultrasonic transducer f With the velocity v after abrasive grain acceleration m The vector sum of the output velocity v of the ultrasonic transducer. f The velocity v is the velocity directly transmitted to the liquid by the periodic vibration of the ultrasonic transducer tool head, which varies periodically with frequency and amplitude; the velocity v after abrasive particle acceleration. m Both are affected by the periodic sound field, and the two need to be superimposed by vector to reflect the total motion speed actually obtained by the abrasive particles.

[0077] Therefore, based on the abrasive particle synthesis rate Determine the kinetic energy U of abrasive impact on the workpiece surface mn include:

[0078] Based on abrasive particle synthesis velocity The energy conversion efficiency η, abrasive grain radius R, and abrasive grain density ρ are used to determine the kinetic energy U of the abrasive grains impacting the workpiece surface. mn The kinetic energy U of abrasive particles impacting the workpiece surface mn for:

[0079]

[0080] The effective abrasive particle synthesis rate, i.e., the abrasive particle synthesis rate, has been obtained. The impact kinetic energy needs to be calculated by combining the physical parameters (density, radius) and energy conversion efficiency of the abrasive grains themselves; the mass m of the abrasive grain is determined by the abrasive grain density ρ and the abrasive grain radius R; considering the conversion efficiency of sound field energy to abrasive grain kinetic energy, i.e., energy conversion efficiency η (which needs to be experimentally calibrated to reflect the proportion of energy loss), the impact kinetic energy of the abrasive grain is:

[0081]

[0082] By combining the movement speed of the abrasive grains with their own mass and energy efficiency, the kinetic energy of the abrasive grains impacting the workpiece is finally obtained, completing the quantitative closed loop of velocity → kinetic energy. By integrating the kinematic parameters of the abrasive grains with their own physical parameters (mass, size) and energy transfer efficiency, the calculation of the abrasive grain impact kinetic energy is accurate and comprehensive, providing directly comparable quantitative indicators.

[0083] Furthermore, based on the kinetic energy U of abrasive impact on the workpiece surface... mn The critical kinetic energy U that causes brittle fracture in the workpiece material c Determine the minimum amplitude A of the ultrasonic transducer. min include:

[0084] The kinetic energy U that causes abrasive grains to impact the workpiece surface mn The kinetic energy U is greater than the critical kinetic energy U required for brittle fracture of the workpiece material. c Determine the minimum amplitude A of the ultrasonic transducer. min .

[0085] For abrasive particles to effectively remove material, the energy condition must be met: U mn >U C Among them, the critical kinetic energy U for the brittle fracture of the workpiece material is... c for:

[0086]

[0087] Where C is the crack mode correlation coefficient, E2 is the elastic modulus of the workpiece, and K IC H represents the fracture strength limit of the workpiece material, and H represents the hardness of the workpiece material.

[0088] Based on U mn >U C The minimum amplitude A of the ultrasonic transducer was calculated. min By using energy matching to lock the minimum amplitude of the oscillator, the processing is ensured to have the energy basis for effectively removing material. At the same time, it provides a benchmark threshold to prevent edge chipping caused by excessive amplitude, thus achieving an initial balance between processing effectiveness and quality control.

[0089] Furthermore, such as Figure 3 As shown, in determining the minimum amplitude A of the ultrasonic transducer... min This also includes:

[0090] Based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the tool feed rate v z ;

[0091] Real-time machining force feedback values ​​are obtained by a force sensor located beneath the workpiece, and the feed rate v is adjusted based on these force feedback values. z .

[0092] Specifically, the microscopic impact kinetic energy of the abrasive grains is converted into the macroscopic feed rate of the tool to obtain the theoretical feed rate, providing a quantitative target for machining efficiency; the feed rate is adjusted in real time through a force sensor. A force sensor is placed below the workpiece to collect the force feedback value of the abrasive grains impacting the workpiece in real time.

[0093] If the force feedback value is higher than the theoretical value, it indicates that the actual material removal rate is less than the feed rate, abrasive particles accumulate on the workpiece surface, the impact force is too large, and there is a risk of edge chipping. The tool feed rate v needs to be reduced. z This ensures that the removal rate matches the feed rate;

[0094] If the force feedback value is lower than the theoretical value, it indicates that the actual material removal rate is greater than the feed rate, resulting in slow processing and low efficiency. The tool feed rate v needs to be increased. z Improve processing efficiency;

[0095] If the drilling depth increases, causing the abrasive circulation to slow down (force feedback to continue to increase): the system automatically lifts the tool to the vicinity of the workpiece surface to replenish the abrasive, and then returns to the original position to continue processing, compensating for the decrease in speed caused by insufficient abrasive.

[0096] The control logic of micro-abrasive impact and macro-tool motion is combined and a real-time feedback mechanism is used to provide quantitative basis for feed rate and to compensate for non-deterministic interferences in the machining process (such as abrasive concentration changes and oscillator parameter drift), which significantly improves the stability of machining quality.

[0097] Among them, the kinetic energy U based on the impact of abrasive particles on the workpiece surface mn Determine the tool feed rate v z include:

[0098] Based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the volume of material removed from the workpiece, V, under the impact of a single abrasive grain. C ;

[0099] Workpiece material removal volume V based on single abrasive grain impact C Determine the tool feed rate v z .

[0100] Specifically, by combining the material's elastic modulus, fracture strength, hardness, and abrasive scattering coefficient, the impact kinetic energy of abrasive particles is converted into the volume of material removed by a single abrasive particle in a single impact, thus quantifying the transformation from microscopic kinetic energy to microscopic removal volume. The removal volume of a single particle is then expanded to the total removal volume per unit time, ultimately yielding the tool feed rate v. zThis process quantifies the transition from microscopic abrasive removal to macroscopic feed. By establishing a quantitative correlation between the microscopic impact behavior of abrasive particles and the macroscopic feed motion of the cutting tool, the feed rate is transformed from an empirical value into a calculable theoretical value, significantly improving the controllability of machining parameters and the predictability of machining efficiency.

[0101] More specifically, based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the volume of material removed from the workpiece, V, under the impact of a single abrasive grain. C include:

[0102] Based on the kinetic energy U of abrasive impact on the workpiece surface mn 1. Elastic modulus E2 of the workpiece; 2. Ultimate fracture strength K of the workpiece material IC And the hardness H of the workpiece material, to determine the volume of material removed V from the workpiece under the impact of a single abrasive grain. C V, the volume of material removed from the workpiece under the impact of a single abrasive grain C for:

[0103]

[0104] Where α is the monopole scattering coefficient of the abrasive grain;

[0105] β is the dipole scattering coefficient of the abrasive grain.

[0106] The kinetic energy U of abrasive impact on the workpiece surface has been obtained. mn 1. Elastic modulus E2 of the workpiece; 2. Ultimate fracture strength K of the workpiece material IC The hardness H of the workpiece material and the single / dipole scattering coefficients α and β of the abrasive grains; the material removal volume under the impact of a single abrasive grain, which is related to the impact kinetic energy of the abrasive grain, the mechanical parameters of the workpiece, and the scattering coefficients of the abrasive grains: the scattering coefficients α and β reflect the proportion of the abrasive grains' scattering ability in the ultrasonic field; the mechanical parameters of the workpiece (elastic modulus E2 of the workpiece, ultimate tensile strength K of the workpiece material). IC The hardness (H) of the workpiece material reflects the material's resistance to removal. The higher the elastic modulus, the stronger the fracture toughness, and the higher the hardness, the more difficult the material is to be removed.

[0107] based on The volume of material removed from the workpiece under the impact of a single abrasive grain, V C This method quantifies the volume removed by kinetic energy. It integrates abrasive kinetic energy, material mechanical properties, and abrasive scattering effects into a quantitative formula for the volume removed by a single particle, making the relationship between microscopic impact and material removal transparent and providing a precise particle-level basis for subsequent feed rate calculations.

[0108] Furthermore, based on the workpiece material removal volume V under the impact of a single abrasive grain... C Determine the tool feed rate v z include:

[0109] Based on the ultrasonic transducer frequency f, abrasive concentration c', and minimum ultrasonic transducer amplitude A min Density ρ of the processing solution l Given the abrasive particle density ρ and the machined hole area S, determine the number of particles N impacting per unit time. The number of particles N impacting per unit time is:

[0110]

[0111] Based on the number of impacting particles N per unit time and the volume of material removed from the workpiece under the impact of a single abrasive grain V. C The ultrasonic transducer frequency f and the machined hole area S are used to determine the tool feed rate v. z Tool feed rate v z for:

[0112]

[0113] The material removal volume V of the workpiece under the impact of a single abrasive grain has been obtained. C Given the ultrasonic transducer frequency f, abrasive concentration c', and machining hole area S, the number of abrasive particles impacting the workpiece per unit time is related to the ultrasonic transducer frequency f (the number of vibrations per second, which determines the abrasive impact frequency), abrasive concentration c' (the volume percentage of abrasive particles in the liquid), machining hole area S (the effective area of ​​abrasive impact), and the minimum ultrasonic transducer amplitude A. min (The effective travel distance by which abrasive particles reach the workpiece surface) and the density ratio ρ of the liquid to the abrasive particles. l / ρ (reflecting the suspension ability of abrasive particles in a liquid) is related to the formula. By integrating ultrasonic parameters, abrasive parameters, and machining geometry parameters, the total number of abrasive impacts per unit time is obtained.

[0114] The tool feed rate is equal to the total volume of material removed by all abrasive grains per unit time divided by the area of ​​the machined hole. The total volume removed per unit time is the volume of workpiece material removed under the impact of a single abrasive grain, V. C Multiply by the number of particles N impacting per unit time, and then multiply by the ultrasonic transducer frequency f (reflecting the contribution of the number of impacts per second to the total removal), therefore:

[0115]

[0116] It achieves the quantification of microscopic single-particle removal to macroscopic feed rate; it integrates macroscopic parameters such as ultrasonic frequency, abrasive concentration, and machining hole size with microscopic parameters of single-particle removal volume, making the feed rate calculation comprehensive and accurate, and providing a directly applicable quantitative basis for the control of processing efficiency and quality.

[0117] To make the technical solution and beneficial effects of this application clearer, the above technical solution will be further described in detail below with reference to specific embodiments:

[0118] For a workpiece with the following material parameters, a 0.6±0.05mm hole is machined using an ultrasonic transducer with a frequency of 15kHz, abrasive material of diamond with a particle radius of 5μm, solvent of water, and abrasive concentration of 3%.

[0119]

[0120]

[0121] The calculated amplitude A = 5.167 μm is just enough for the abrasive grains to cause brittle fracture of the material. In practice, it is taken to be slightly larger than the critical value, that is, the minimum amplitude A of the ultrasonic transducer. min =8-12μm, based on the theoretically calculated tool feed rate v z Feed rate: Initially, the force sensor feedback value is 3g. If the force sensor feedback value gradually increases, the tool feed rate v... z The force sensor value should be reduced accordingly until it stabilizes; otherwise, the tool feed rate v should be increased. z The sensor value was increased accordingly until it stabilized. The theoretical and measured values ​​under different output amplitudes are compared below:

[0122]

[0123] Based on the table above, when machining a 0.6±0.05mm hole, considering the workpiece's elastic modulus (193GPa) and ultimate tensile strength (1500MPa), 1 / 2 Based on parameters such as abrasive kinetic energy, the critical amplitude for brittle fracture of the material was calculated to be 5.167 μm. In practice, 8-12 μm was taken as the minimum amplitude of the ultrasonic transducer. The processing rate for different abrasive radii (8-12 μm) was tested: the theoretical processing rate increased from 0.0850 μm / s to 0.1041 μm / s with increasing abrasive radius, and the actual processing rate increased synchronously. Furthermore, the error between the theoretical and actual rates was within 6.3%-12%, indicating a high degree of matching. Simultaneously, the force sensor feedback during processing dynamically adjusted the feed rate, maintaining processing stability. This demonstrates that the quantitative calculation model of the technical solution is accurate, can optimize efficiency according to abrasive parameters, provides real-time feedback to ensure a balance between quality and efficiency, and lowers the operational threshold, exhibiting significant advantages.

[0124] The ultrasonic micro-hole machining method of this application improves the quality of micro-hole machining through technical solutions such as quantitative energy matching, quantitative material removal volume, precise control of feed rate, and real-time feedback adjustment. Specifically, the quantitative correlation between the ultrasonic transducer amplitude, the abrasive impact kinetic energy, and the critical fracture kinetic energy of the material ensures that the abrasive kinetic energy just meets the requirements of brittle fracture of the material. This avoids both edge chipping and crack propagation caused by excessive kinetic energy and machining stagnation caused by insufficient kinetic energy, and is especially suitable for micro-hole machining of hard and brittle materials such as diamond and sapphire.

[0125] By establishing a quantitative correlation between the microscopic removal behavior of a single abrasive grain and the macroscopic feed motion of the tool, operators do not need to rely on experience. They only need to input material parameters, abrasive grain parameters, and ultrasonic parameters to calculate the theoretical feed rate through formulas, which greatly reduces the technical threshold and trial and error costs.

[0126] The closed-loop feedback mechanism of the force sensor dynamically compensates for various disturbances during the processing (such as changes in abrasive concentration and fluctuations in oscillator parameters), ensuring that the processing force and material removal rate are always maintained within the theoretically optimal range, and significantly improving the consistency of processing quality (dimensional accuracy, surface roughness, chipping rate, etc.).

[0127] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0128] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for ultrasonic micro-hole fabrication, characterized in that, include: Obtain the initial amplitude A of the ultrasonic transducer, and based on the initial amplitude A, determine the kinetic energy U of the abrasive particles impacting the workpiece surface. mn ; Obtain or calculate the critical kinetic energy U at which the workpiece material undergoes brittle fracture. c ; Based on the kinetic energy U of abrasive impact on the workpiece surface mn The critical kinetic energy U that causes brittle fracture in the workpiece material c Determine the minimum amplitude A of the ultrasonic transducer. min .

2. The ultrasonic micro-hole fabrication method according to claim 1, characterized in that, The kinetic energy U of the abrasive particles impacting the workpiece surface is determined based on the initial amplitude A. mn include: Based on the initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer f Determine the velocity v of the abrasive particles after acceleration. m ; Based on the vibration velocity v at the output end of the ultrasonic transducer f and the velocity v after abrasive acceleration m Determine the abrasive particle synthesis rate Based on abrasive particle synthesis velocity Determine the kinetic energy U of abrasive impact on the workpiece surface mn .

3. The ultrasonic micro-hole fabrication method according to claim 2, characterized in that, The initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer are mentioned. f Determine the velocity v of the abrasive particles after acceleration. m include: Based on the initial amplitude A and the vibration velocity v at the output end of the ultrasonic transducer f Density ρ of the processing solution l The speed of ultrasound propagation in a liquid, c, is used to determine the air pressure P generated at the output end of the ultrasonic transducer. The air pressure P generated at the output end of the ultrasonic transducer is: Qρ l ·c·v f Based on the air pressure P generated at the output end of the ultrasonic transducer, atmospheric pressure P0, and saturated vapor pressure P inside the cavitation bubble. in and the density ρ of the processing solution l Determine the velocity v of the abrasive particles after acceleration. m The velocity v of the abrasive particles after acceleration m for:

4. The ultrasonic micro-hole fabrication method according to claim 2, characterized in that, The vibration velocity v at the output end of the ultrasonic transducer f and the velocity v after abrasive acceleration m Determine the abrasive particle synthesis rate include: Based on the vibration velocity v at the output end of the ultrasonic transducer f The velocity v of the abrasive particles after acceleration m And the cycle time T, to determine the abrasive particle synthesis rate. The abrasive particle synthesis rate for:

5. The ultrasonic micro-hole fabrication method according to claim 2, characterized in that, The abrasive particle synthesis velocity Determine the kinetic energy U of abrasive impact on the workpiece surface mn include: Based on abrasive particle synthesis velocity The energy conversion efficiency η, abrasive grain radius R, and abrasive grain density ρ are used to determine the kinetic energy U of the abrasive grains impacting the workpiece surface. mn The kinetic energy U of the abrasive particles impacting the workpiece surface mn for:

6. A method for ultrasonic micro-hole fabrication according to any one of claims 1-5, characterized in that, The kinetic energy U based on abrasive impact on the workpiece surface mn The critical kinetic energy U that causes brittle fracture in the workpiece material c Determine the minimum amplitude A of the ultrasonic transducer. min include: The kinetic energy U that causes abrasive grains to impact the workpiece surface mn The kinetic energy U is greater than the critical kinetic energy U required for brittle fracture of the workpiece material. c Determine the minimum amplitude A of the ultrasonic transducer. min .

7. The ultrasonic micro-hole fabrication method according to any one of claims 1-5, characterized in that, Determining the minimum amplitude A of the ultrasonic transducer min This also includes: Based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the tool feed rate v z ; Real-time machining force feedback values ​​are obtained by a force sensor located beneath the workpiece, and the feed rate v is adjusted based on these force feedback values. z .

8. The ultrasonic micro-hole fabrication method according to claim 7, characterized in that, The kinetic energy U based on abrasive impact on the workpiece surface mn Determine the tool feed rate v z include: Based on the kinetic energy U of abrasive impact on the workpiece surface mn Determine the volume of material removed from the workpiece, V, under the impact of a single abrasive grain. C ; Workpiece material removal volume V based on single abrasive grain impact C Determine the tool feed rate v z .

9. The ultrasonic micro-hole fabrication method according to claim 8, characterized in that, The kinetic energy U based on abrasive impact on the workpiece surface mn Determine the volume of material removed from the workpiece, V, under the impact of a single abrasive grain. C include: Based on the kinetic energy U of abrasive impact on the workpiece surface mn 1. Elastic modulus E2 of the workpiece; 2. Ultimate fracture strength K of the workpiece material IC And the hardness H of the workpiece material, to determine the volume of material removed V from the workpiece under the impact of a single abrasive grain. C The volume of workpiece material removed V under the impact of a single abrasive grain C for: Where α is the monopole scattering coefficient of the abrasive grain; β is the dipole scattering coefficient of the abrasive grain.

10. The ultrasonic micro-hole fabrication method according to claim 8, characterized in that, The workpiece material removal volume V based on the impact of a single abrasive grain C Determine the tool feed rate v z include: Based on the ultrasonic transducer frequency f, abrasive concentration c', and minimum ultrasonic transducer amplitude A min Density ρ of the processing solution l Based on the abrasive particle density ρ and the machining hole area S, the number of particles N impacting per unit time is determined. The number of particles N impacting per unit time is: Based on the number of impacting particles N per unit time and the volume of material removed from the workpiece under the impact of a single abrasive grain V. C The ultrasonic transducer frequency f and the machined hole area S are used to determine the tool feed rate v. z The tool feed rate v z for:

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