A method for field-assisted machining of micro-holes in a hard and brittle ceramic matrix composite material

Abstract

The application discloses a kind of hard brittle ceramic matrix composite micro-hole energy field assisted processing methods, which is quickly processed by laser ablation to micro-hole, reduces the material removal allowance of subsequent hole processing, and can solve the problem of low tool rigidity and easy breakage in the process of hard brittle ceramic matrix composite micro-hole processing;At the same time, after laser bottom hole processing, ultrasonic assisted drilling is selected for micro-hole finishing, which ensures the quality of micro-hole.The method is based on laser ablation finite element simulation, ultrasonic tool handle modal simulation, ultrasonic assisted micro-hole drilling simulation, and a small number of test verification and correction, which greatly reduces the test workload in previous drilling research, reduces the dependence of process parameter selection on engineering technical experience, and can obtain more extensive data and rules of process parameter range.

Description

Technical Field

[0001] The invention belongs to the technical field of hard-brittle composite material processing, and in particular relates to a micro-pore energy field assisted processing method of hard-brittle ceramic-based composite materials. Background Art

[0002] Brittle-hard ceramic matrix composites (CMCs) are a type of composite material reinforced with rigid fibers that have been developed in recent years. While retaining the inherent high-temperature resistance, oxidation resistance, wear resistance, and low density of ceramic materials, the presence of rigid reinforcing fibers enhances the material's toughness and significantly improves its impact load resistance. Advanced CMCs can operate at temperatures of 1200°C to 1500°C without film cooling or thermal barrier coatings, yet possess a density only one-third that of high-temperature alloys. These materials hold great promise for applications in aerospace, automotive, transportation, and other industries.

[0003] With the continuous development and advancement of ceramic matrix composite (CMC) manufacturing processes, the densification level of these materials has been significantly improved. For example, CMCs prepared using reactive / non-reactive melt infiltration (RMI / MI) have higher density and lower porosity than those prepared using chemical vapor infiltration (CVI) and polymer impregnation pyrolysis (PIP). Correspondingly, RMI / MI CMCs have slightly higher density, better wear resistance, and poorer machinability. CMCs have excellent high-temperature resistance and hold great promise for application in the aerospace sector, making them an ideal material for critical high-temperature components in the aerospace sector.

[0004] Air film hole processing, especially the processing of micro holes with a diameter of less than Φ1.0mm, is the main task in the processing and manufacturing of high-temperature parts in the aerospace industry. However, due to the high hardness of ceramic-based composites, which is higher than the hardness of commonly used cutting tools and the strong wear resistance of the material, ceramic-based composites face a series of difficulties when processing micro holes, such as: poor material machinability, severe tool wear, and even difficulty in cutting the material; the drill bit is prone to slipping and breaking when drilling into the surface of the ceramic-based composite material, and drilling of micro holes is difficult to achieve; the ceramic-based composite material prepared by the CVI / PIP process has a high porosity and an uneven distribution inside the material. The drill bit is subjected to uneven force during the drilling process and is prone to breaking and getting stuck during the drilling process; the micro hole has a small diameter (Φ0.7mm, Φ0.5mm), a large aspect ratio, and low drilling tool stiffness; current research is mainly based on trial and error, with a large amount of experiments, and parameter matching and optimization are still one of the current difficulties in the processing of ceramic-based composite materials.

[0005] Chinese patent application CN111002483A discloses a method and a drilling mechanism for machining holes in ceramic-based composite components. The method uses a preform of a ceramic-based composite component before the CVI process to drill holes, with a hole diameter range of 1.2 mm to 40 mm. The preform has a lower hardness than the material after the CVI process, making it easier to machine, and has a larger hole diameter, making it easier to machine. Chinese patent application CN115848616A discloses a ceramic-based composite rudder shaft connection structure, a hole-making tool, and a riveted hole production method, wherein the diameter of the drilled hole in the ceramic-based composite material is much larger than the size of the micro-hole (D ≤ Φ1.0 mm). However, there are no reports on the machining of micro-holes (D ≤ Φ1.0 mm) in ceramic-based composite materials with higher density prepared by the RMI / MI process. The tool used in the machining of micro-holes in hard and brittle ceramic-based composite materials has low rigidity and is easily broken, requiring a large amount of testing. The selection of machining parameters relies heavily on engineering experience, making it impossible to achieve efficient and high-quality machining of micro-holes in ceramic-based composite materials. Summary of the Invention

[0006] In view of this, in order to overcome the problems of poor tool stiffness and easy breakage during the micro-hole processing of ceramic matrix composites, especially denser ceramic matrix composites prepared by RMI / MI process, large amount of process exploration experiments, and low target orientation, the present invention provides a micro-hole energy field assisted processing method for hard and brittle ceramic matrix composites, the method comprising:

[0007] Step 1): Constructing a finite element model for millisecond laser ablation simulation of ceramic matrix composites;

[0008] Step 2): According to the ablation diameter D and the peak laser energy density F pk The relationship function, formula (1), calculates the required peak laser energy density F corresponding to different laser processing hole diameters pk :

[0009]

[0010] Step 3): Calculate the peak laser energy density F corresponding to the different laser processing hole diameters pk As the initial reference value, with the help of the finite element model constructed in step 1), the laser ablation simulation analysis of ceramic matrix composites is carried out to obtain the generalized inward heat flux H, as shown in formula (2):

[0011] H=η(x-x0)*P*λ(t) (2)

[0012] Where η is the Gaussian distribution function used to simulate the laser energy density distribution; P is the laser energy density, which is calculated as follows: P = P_total / (pi*r 2*k), P_total is the total laser power, r is the spot radius, k is the laser frequency; λ is a sawtooth wave function used to simulate the energy change of pulsed laser over time;

[0013] Step 4): Conduct laser ablation tests on a small number of ceramic matrix composites and compare and verify the laser ablation simulation results;

[0014] Step 5): Based on the test results of step 4), the finite element simulation analysis of step 3) is reasonably revised, and step 3) is repeated to comprehensively consider the processing efficiency of laser processing of the material to obtain the corresponding relationship between the revised laser processing hole diameter and the laser processing parameters;

[0015] Step 6): Constructing a finite element simulation model of ultrasonic-assisted drilling of ceramic matrix composite materials;

[0016] Step 7): Based on the finite element simulation model constructed in step 6), a modal simulation analysis is performed on the ultrasonic tool holder and the drilling tool to obtain a suitable tool clamping overhang and ultrasonic vibration parameter range;

[0017] Step 8): Conduct finite element simulation of ultrasonic-assisted drilling of ceramic matrix composite materials using the finite element simulation model from step 6), the tool clamping overhang and ultrasonic vibration parameter range from step 7, and the laser-processed hole diameter from step 5;

[0018] Step 9): Using a neural network algorithm, a mapping relationship between the laser processing hole diameter, ultrasonic assisted drilling process parameters and the micro-hole diameter is constructed;

[0019] Step 10): Conduct ultrasonic-assisted drilling tests on a small number of ceramic matrix composite materials to verify the mapping relationship obtained in step 9), and modify the model in step 9) based on the test results;

[0020] Step 11): Based on the modified mapping model and the target aperture size of the micro-hole obtained in step 10), the laser processing hole diameter and the ultrasonic-assisted drilling process parameters of the ceramic matrix composite material are determined;

[0021] Step 12): Determine the laser processing parameters according to the laser processing hole diameter determined in step 11) and the corresponding relationship between the laser processing hole diameter and the laser processing parameters in step 5);

[0022] Step 13): According to the laser processing parameters and ultrasonic-assisted drilling process parameters determined in steps 11) and 12), micro-hole processing of the ceramic matrix composite material is performed.

[0023] Furthermore, in step 1), a millisecond laser ablation simulation finite element model of SiC / SiC ceramic matrix composites prepared by RMI process was constructed in Comsol Multiphysics 5.0 multi-physics field finite element simulation software.

[0024] Furthermore, in step 2), the hot melt ablation F of the ceramic matrix composite material th Take 0.30J / cm 2 .

[0025] Furthermore, in step 4) and step 10), the small number of groups is 2 or 3 groups.

[0026] Furthermore, in step 4) and step 10), the small number of groups is 2 groups.

[0027] Furthermore, in step 7), the tool clamping overhang is 20 to 30 mm, and the ultrasonic frequency range is 20 kHz to 40 kHz.

[0028] Furthermore, in step 9), the mapping relationship between the laser processing hole diameter, ultrasonic assisted drilling process parameters and the micro-hole diameter;

[0029] D=0.4802·d 0.03026 ·n 0.0088 ·f -0.00366 (3)

[0030] Where D is the micro-hole diameter, d is the laser processing hole diameter, n is the spindle speed, and f is the feed speed.

[0031] Furthermore, in step 12), the millisecond laser processing parameters are: peak power 1000W, scanning speed 1mm / s, repetition frequency 144Hz, pulse width 0.5ms, blowing pressure 0.8MPa, number of scans 6 times, the first 3 processing diameters are Φ0.14mm, the defocus amount is 0mm, the last 3 processing diameters are Φ0.16mm, the defocus amount is -1.5mm, and the laser processing bottom hole diameter is Φ0.30mm.

[0032] Furthermore, in step 13), the ultrasonic-assisted drilling parameters are: spindle speed 13100 r / min, feed speed 6 mm / min, vibration frequency 29.6 kHz, and amplitude 2.1 μm.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The method of the present invention uses laser ablation to quickly process tiny bottom holes, reducing the material removal allowance in subsequent hole processing, and can solve the problems of low tool stiffness and easy breakage in the process of processing tiny holes in hard and brittle ceramic-based composite materials. At the same time, after laser bottom hole processing, ultrasonic assisted drilling is used to perform fine processing of the tiny holes, ensuring the quality of the tiny holes.

[0035] 2. The method of the present invention is based on laser ablation finite element simulation, ultrasonic toolholder modal simulation, and ultrasonic-assisted micro-hole drilling simulation, and is verified and corrected through a small number of test groups. It greatly reduces the experimental workload in previous drilling research, reduces the dependence of process parameter selection on engineering technical experience, and can obtain data and laws with a wider range of process parameters, which is impossible to achieve in actual processing test research. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the technical route of the micro-pore energy field assisted processing method of the hard and brittle ceramic-based composite material of the present invention.

[0037] Figure 2 This is a comparison chart of the porosity / density of CVI ceramic matrix composites and RMI ceramic matrix composites.

[0038] Figure 3 Schematic diagram of the correlation between the ablation area and the laser energy density.

[0039] Figure 4 This is a finite element simulation diagram of laser ablation simulation of ceramic matrix composites.

[0040] Figure 5 is the Gaussian distribution function.

[0041] Figure 6 is a sawtooth wave function.

[0042] Figure 7 It is a finite element simulation model of ultrasonic assisted drilling.

[0043] Figure 8 It is a schematic diagram of the structure of ultrasonic assisted drilling tool.

[0044] Figure 9 This is the modal finite element analysis diagram of the ultrasonic assisted drilling tool holder.

[0045] Figure 10 This is a finite element analysis diagram of laser ablation of ceramic matrix composites.

[0046] Figure 11 This is a diagram of ultrasonic-assisted drilling of ceramic matrix composites.

[0047] Figure 12 This is a picture of tiny holes in a ceramic matrix composite material obtained by processing according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention and the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] This invention provides a method for energy-field-assisted micro-hole machining of hard and brittle ceramic-based composite materials. This method, based on finite element simulation of laser ablation, modal simulation of ultrasonic toolholders, and simulation of ultrasonic-assisted micro-hole drilling, has been verified and refined through a small number of experimental sets. This method significantly reduces the experimental workload in previous drilling research, reduces the reliance on engineering experience for process parameter selection, and enables the acquisition of data and patterns across a wider range of process parameters. Figure 1 Schematic diagram of the technical route of the micro-pore energy field assisted processing method of hard and brittle ceramic matrix composite materials of the present invention is shown in FIG. Figure 2 The pore / density comparison diagram of CVI ceramic matrix composites and RMI ceramic matrix composites is shown schematically. The correlation between the ablation area and the laser energy density is shown schematically. Figure 3 middle.

[0050] The following is an explanation using SiC / SiC ceramic matrix composite material as an example.

[0051] This embodiment provides a method for micro-pore energy field-assisted processing of hard and brittle ceramic matrix composite materials, comprising:

[0052] Step 1): Constructing a millisecond laser ablation simulation finite element model of SiC / SiC ceramic matrix composites prepared by RMI process in Comsol Multiphysics 5.0 multi-physics field finite element simulation software; Figure 4 The finite element simulation diagram of laser ablation of ceramic matrix composite materials is shown in the figure. The main parameters of the finite element simulation model are shown in Table 1 below;

[0053] Table 1 Main parameters of finite element simulation model

[0054]

[0055] Step 2): According to the ablation diameter D and the peak laser energy density F pk The relationship function, formula (1), calculates the required peak laser energy density F corresponding to different laser processing hole diameters pk Among them, the hot melt ablation F of SiC / SiC ceramic matrix composites th Take 0.30J / cm 2(Zhang Fusheng. Femtosecond laser processing mechanism and experimental study of silicon carbide composites[D]. Liaoning: Liaoning University of Engineering and Technology, 2023.)

[0056]

[0057] Step 3): Calculate the peak laser energy density F corresponding to the different laser processing hole diameters pk As the initial reference value, with the help of the finite element model constructed in step 1), the laser ablation simulation analysis of SiC / SiC ceramic matrix composites was carried out to obtain the generalized inward heat flux H, as shown in formula (2). By adjusting the parameters to fit the material removal efficiency of the laser processing material removal process in the experiment, the actual laser prefabricated hole preparation experiment was guided;

[0058] H=η(x-x0)*P*λ(t) (2)

[0059] Where η is the Gaussian distribution function used to simulate the laser energy density distribution; P is the laser energy density, which is calculated as follows: P = P_total / (pi*r 2 *k), P_total is the total laser power, r is the spot radius, k is the laser frequency; λ is a sawtooth wave function used to simulate the energy change of pulsed laser over time; Figure 5 and Figure 6 The Gaussian distribution function and the sawtooth wave function are shown in FIG.

[0060] Step 4): Conduct two sets of RMI process SiC / SiC ceramic matrix composite laser ablation tests and compare and verify with the laser ablation simulation results;

[0061] Step 5): Based on the test results of step 4), the finite element simulation analysis of step 3) is reasonably revised, and step 3) is repeated to comprehensively consider the processing efficiency of laser processing of the material type, and obtain the corresponding relationship between the revised laser processing aperture and the laser processing parameters;

[0062] Step 6): Construct a finite element simulation model of ultrasonic-assisted drilling of SiC / SiC ceramic matrix composites in RMI process. Figure 7 A finite element simulation model of ultrasonic assisted drilling is shown;

[0063] Step 7): Based on the finite element simulation model constructed in step 6), a modal simulation analysis is performed on the ultrasonic tool holder and the drilling tool to obtain a suitable tool clamping overhang and ultrasonic vibration parameter range. The tool clamping overhang is 20 to 30 mm, and the ultrasonic frequency range is 20 kHz to 40 kHz. Figure 8 The structure of the ultrasonic assisted drilling tool is schematically shown in FIG. Figure 9 This is the modal finite element analysis diagram of the ultrasonic assisted drilling tool holder.

[0064] Step 8): Using the finite element simulation model from step 6), the tool clamping overhang and ultrasonic vibration parameter range from step 7, and the laser processing hole diameter from step 5, carry out finite element simulation of ultrasonic-assisted drilling of SiC / SiC ceramic matrix composites in RMI process. Figure 10 The finite element analysis diagram of laser ablation of ceramic matrix composites is shown in;

[0065] Step 9): Using a neural network algorithm, a mapping relationship between the laser processing hole diameter, ultrasonic assisted drilling process parameters and the micro-hole diameter is constructed;

[0066] D=0.4802·d 0.03026 ·n 0.0088 ·f -0.00366 (3)

[0067] Where D is the micro-hole diameter, d is the laser processing hole diameter, n is the spindle speed, and f is the feed speed.

[0068] Step 10): Conduct two sets of ultrasonic-assisted drilling tests on ceramic matrix composite materials to verify the mapping relationship obtained in step 9), and modify the model in step 9) based on the test results. Figure 11 Figure 2 shows ultrasonic-assisted drilling of ceramic matrix composite materials;

[0069] Step 11): Based on the modified mapping model obtained in step 10) and the target aperture size of the micro-hole (Φ0.5 mm), the laser processing hole diameter and the ultrasonic assisted drilling process parameters of the SiC / SiC ceramic matrix composite material in the RMI process are determined;

[0070] Step 12): Determine the laser processing parameters based on the laser processing hole diameter determined in step 11) and the correspondence between the laser processing hole diameter and the laser processing parameters in step 5); the millisecond laser processing parameters are: peak power 1000W, scanning speed 1mm / s, repetition frequency 144Hz, pulse width 0.5ms, blowing pressure 0.8MPa, number of scans 6 times, the first 3 processing diameters are Φ0.14mm, the defocus amount is 0mm, the last 3 processing diameters are Φ0.16mm, the defocus amount is -1.5mm, and the laser processing bottom hole diameter is Φ0.30mm.

[0071] Step 13): Based on the laser processing parameters and ultrasonic-assisted drilling process parameters determined in steps 11) and 12), RMI (Remote Motion Injection Molding) process was performed to machine micro-holes in SiC / SiC ceramic matrix composites. The ultrasonic-assisted drilling parameters were: spindle speed 13,100 rpm, feed rate 6 mm / min, vibration frequency 29.6 kHz, amplitude 2.1 μm, and cooling.

[0072] The target diameter of the micro-holes in the SiC / SiC ceramic matrix composite material produced by the RMI process is Φ0.5 mm. The diameters of the micro-holes processed in the embodiment are 0.502 mm, 0.503 mm, and 0.507 mm, respectively. Figure 12 FIG. 3 shows a diagram of micropores in a ceramic matrix composite material obtained by processing an embodiment of the present invention.

[0073] It can be seen that the embodiment of the present invention uses laser ablation to quickly process tiny bottom holes, reduces the material removal allowance in subsequent hole processing, and can solve the problems of low tool stiffness and easy breakage in the process of processing tiny holes in hard and brittle ceramic-based composite materials; at the same time, after laser bottom hole processing, ultrasonic assisted drilling is used to perform fine processing of the tiny holes, so that the processed tiny holes of the ceramic-based composite material are of good quality; and through verification and correction by a small number of groups of experiments, the experimental workload in previous drilling research has been greatly reduced, and the dependence of the selection of process parameters on engineering technical experience has been reduced, so that data and laws with a wider range of process parameters can be obtained, which is impossible to achieve in actual processing test research.

[0074] It should be noted that the above-described embodiments are merely preferred embodiments of the present invention. Persons skilled in the art will appreciate that various modifications, improvements, and equivalent substitutions may be made to the present invention without departing from the principles of the present invention, and such modifications, improvements, and equivalent substitutions are deemed to fall within the scope of protection of the claims of the present invention.

Claims

1. A micropore energy field-assisted processing method for hard and brittle ceramic matrix composite materials, comprising: Step 1): Constructing a finite element model for millisecond laser ablation simulation of ceramic matrix composites; Step 2): According to the ablation diameter D and the peak laser energy density F pk The relationship function, formula (1), calculates the required peak laser energy density F corresponding to different laser processing hole diameters pk : Step 3): Calculate the peak laser energy density F corresponding to the different laser processing hole diameters pk As the initial reference value, with the help of the finite element model constructed in step 1), the laser ablation simulation analysis of ceramic matrix composites is carried out to obtain the generalized inward heat flux H, as shown in formula (2): H=η(x-x0)*P*λ(t) (2) Where η is the Gaussian distribution function used to simulate the laser energy density distribution; P is the laser energy density, which is calculated as follows: P = P_total / (pi*r 2 *k), P_total is the total laser power, r is the spot radius, k is the laser frequency; λ is a sawtooth wave function used to simulate the energy change of pulsed laser over time; Step 4): Conduct laser ablation tests on a small number of ceramic matrix composites and compare and verify the laser ablation simulation results; Step 5): Based on the test results of step 4), the finite element simulation analysis of step 3) is reasonably revised, and step 3) is repeated to comprehensively consider the processing efficiency of laser processing of the material to obtain the corresponding relationship between the revised laser processing hole diameter and the laser processing parameters; Step 6): Constructing a finite element simulation model of ultrasonic-assisted drilling of ceramic matrix composite materials; Step 7): Based on the finite element simulation model constructed in step 6), a modal simulation analysis is performed on the ultrasonic tool holder and the drilling tool to obtain a suitable tool clamping overhang and ultrasonic vibration parameter range; Step 8): Conduct finite element simulation of ultrasonic-assisted drilling of ceramic matrix composite materials using the finite element simulation model from step 6), the tool clamping overhang and ultrasonic vibration parameter range from step 7, and the laser-processed hole diameter from step 5; Step 9): Using a neural network algorithm, a mapping relationship between the laser processing hole diameter, ultrasonic assisted drilling process parameters and the micro-hole diameter is constructed; Step 10): Conduct ultrasonic-assisted drilling tests on a small number of ceramic matrix composite materials to verify the mapping relationship obtained in step 9), and modify the model in step 9) based on the test results; Step 11): Based on the modified mapping model and the target aperture size of the micro-hole obtained in step 10), the laser processing hole diameter and the ultrasonic-assisted drilling process parameters of the ceramic matrix composite material are determined; Step 12): Determine the laser processing parameters according to the laser processing hole diameter determined in step 11) and the corresponding relationship between the laser processing hole diameter and the laser processing parameters in step 5); Step 13): According to the laser processing parameters and ultrasonic-assisted drilling process parameters determined in steps 11) and 12), micro-hole processing of the ceramic matrix composite material is performed.

2. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1 is characterized in that: In step 1), a millisecond laser ablation simulation finite element model of SiC / SiC ceramic matrix composites prepared by RMI process is constructed in Comsol Multiphysics 5.0 multi-physics field finite element simulation software.

3. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1 is characterized in that: In step 2), the hot melt ablation F of the ceramic matrix composite material th Take 0.30J / cm 2 .

4. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1, characterized in that: In step 4) and step 10), the small number of groups is 2 or 3 groups.

5. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1, characterized in that: In step 4) and step 10), the small number of groups is 2 groups.

6. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1, characterized in that: In step 7), the tool clamping overhang is 20 to 30 mm, and the ultrasonic frequency range is 20 kHz to 40 kHz.

7. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1, characterized in that: In step 9), the mapping relationship between the laser processing hole diameter, ultrasonic assisted drilling process parameters and the micro-hole diameter; D=0.4802·d 0.03026 ·n 0.0088 ·f -0.00366 (3) Where D is the micro-hole diameter, d is the laser processing hole diameter, n is the spindle speed, and f is the feed speed.

8. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1, characterized in that: In step 12), the millisecond laser processing parameters are: peak power 1000W, scanning speed 1mm / s, repetition frequency 144Hz, pulse width 0.5ms, blowing pressure 0.8MPa, number of scans 6 times, the first 3 processing diameters are Φ0.14mm, the defocus amount is 0mm, the last 3 processing diameters are Φ0.16mm, the defocus amount is -1.5mm, and the laser processing bottom hole diameter is Φ0.30mm.

9. The micropore energy field assisted processing method for hard and brittle ceramic matrix composite materials according to claim 1, characterized in that: In step 13), the ultrasonic assisted drilling parameters are: spindle speed 13100 r / min, feed speed 6 mm / min, vibration frequency 29.6 kHz, and amplitude 2.1 μm.

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