A machining apparatus and method for ceramic matrix composites

Abstract

The application discloses a processing device and method for ceramic matrix composites, and belongs to the technical field of ceramic material processing, and aims to solve the problems of low machining efficiency, fast tool wear, easy production of defects such as tearing and burr and the like of ceramic matrix composites in the prior art. The device comprises an electric arc processing unit and an ultrasonic vibration auxiliary processing unit. The electric arc processing unit comprises a power supply, an electrode, a processing tool and a soft conductive gasket. The workpiece of the ceramic matrix composite is connected with the positive pole of the power supply, the electrode is connected with the negative pole of the power supply, the upper surface of the processing tool is provided with a groove, and the soft conductive gasket is arranged between the side wall of the workpiece and the groove wall, so that the workpiece is suspended and arranged in the groove. The ultrasonic vibration auxiliary processing unit comprises a milling and grinding head and an ultrasonic vibration generator for driving the ultrasonic vibration of the milling and grinding head. The application can be used for the processing of ceramic matrix composites.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic material processing, and particularly relates to a processing device and method for ceramic matrix composite materials. BACKGROUND

[0002] The ceramic matrix composite material has a wide application prospect in high-temperature thermal end components due to the advantages of high-temperature resistance, wear resistance, high strength, ablation resistance, and light weight. In the processing of the ceramic matrix composite material, damage is prone to occur, and in the mechanical processing (such as grinding or ultrasonic processing), it is difficult to process, the processing efficiency is low, the tool wears fast, and defects such as tearing and burrs are generated due to the cutting force generated by the interaction between the tool and the material. SUMMARY

[0003] In view of the above analysis, the present application aims to provide a processing device and method for ceramic matrix composite materials to solve the problems of low mechanical processing efficiency, fast tool wear, and easy generation of defects such as tearing and burrs in the prior art.

[0004] The purpose of the present application is mainly realized through the following technical solutions:

[0005] The present application provides a processing device for ceramic matrix composite materials, comprising an electric arc processing unit and an ultrasonic vibration assisted processing unit.

[0006] The electric arc processing unit comprises a power supply, an electrode, a processing tooling, and a soft conductive gasket. The workpiece of the ceramic matrix composite material is connected to the positive electrode of the power supply, the electrode is connected to the negative electrode of the power supply, the upper surface of the processing tooling is provided with a groove, and the soft conductive gasket is arranged between the side wall of the workpiece and the groove wall, so that the workpiece is suspended and erected in the groove.

[0007] The ultrasonic vibration assisted processing unit comprises a milling and grinding head and an ultrasonic vibration generator for driving the ultrasonic vibration of the milling and grinding head.

[0008] Further, it further comprises a cooling water vapor supply unit, and the electrode is provided with a central hole in the axial direction, one end of the central hole is connected to the cooling water vapor supply unit, and the other end of the central hole faces the workpiece.

[0009] Further, it further comprises a lateral water spraying unit, and the water outlet of the lateral water spraying unit faces the contact surface of the electrode and the workpiece.

[0010] Further, the spindle speed of the electrode is 300-900 r / min.

[0011] Further, the soft conductive gasket is a soft copper sheet gasket.

[0012] Further, the milling and grinding head is a diamond milling and grinding head.

[0013] Further, the power supply is a pulse power supply.

[0014] Further, the pulse power supply has a voltage of 22-28V, a frequency of 300-900Hz and a duty cycle of 60%-90%.

[0015] Further, the electrode is a red copper electrode or a tungsten copper electrode.

[0016] The application also provides a processing method for ceramic matrix composites, which uses the processing device.

[0017] Compared with the prior art, the application has at least the following beneficial effects:

[0018] The processing device for ceramic matrix composites provided by the application can compensate for the gap between the workpiece and the processing tooling, ensure the adhesion of the workpiece and the processing tooling, avoid the generation of gap voltage, and maintain the continuous discharge of arc processing, by adding a soft conductive gasket between the workpiece and the processing tooling, in view of the anisotropy and weak conductivity of the ceramic matrix composites.

[0019] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application.

[0021] Figure 1 FIG. 1 is a structural schematic view of a processing device for ceramic matrix composites according to an embodiment of the application.

[0022] Reference Signs List:

[0023] 1 - power supply; 2 - electrode; 3 - processing tooling; 4 - soft conductive gasket; 5 - central hole; 6 - lateral water spraying unit; 7 - workpiece; 8 - cooling water vapor supply unit. DETAILED DESCRIPTION

[0024] The preferred application of the application will be specifically described below in combination with the drawings, wherein the drawings constitute a part of the application and are used together with the application to explain the principles of the application.

[0025] Embodiment One

[0026] This embodiment provides a processing device for ceramic matrix composites, as shown in FIG. 1. Figure 1, including an electric arc machining unit and an ultrasonic vibration assisted machining unit, wherein the electric arc machining unit comprises a power supply 1, an electrode 2, a machining tool 3 and a soft conductive gasket 4 (for example, a soft copper gasket or the like), the workpiece 7 is connected to the positive electrode of the power supply 1, the electrode 2 is connected to the negative electrode of the power supply 1, the upper surface of the machining tool 3 is provided with a groove, and the soft conductive gasket 4 is arranged between the side wall of the workpiece 7 and the groove wall, so that the workpiece 7 is suspended and arranged in the groove; the ultrasonic vibration assisted machining unit comprises a milling and grinding head (for example, a diamond milling and grinding head) and an ultrasonic vibration generator for driving the milling and grinding head to vibrate ultrasonically.

[0027] In implementation, the workpiece 7 of the ceramic matrix composite material is rough machined by the electric arc machining unit, and the workpiece 7 of the ceramic matrix composite material is fine machined by the ultrasonic vibration assisted machining unit.

[0028] The ceramic matrix composite material is a C / SiC composite material composed of carbon fibers and silicon carbide, wherein the carbon fibers are in a net matrix structure, the silicon carbide is filled into the mesh holes of the net matrix structure, and a continuous coating of silicon carbide is covered on the surface layer of the composite material. Since the hardness of the ceramic matrix composite material is large, a gap may exist between the ceramic matrix composite material and the machining tool when the electric arc machining is used, which is easy to produce a gap voltage, resulting in that the ceramic matrix composite material cannot complete the electric arc machining, and even the machining tool and the ceramic matrix composite material are damaged.

[0029] The electric arc machining requires that the workpiece 7 and the machining tool 3 maintain good conductivity, but since a gap may exist between the contact surfaces of the workpiece 7 and the machining tool 3, a gap voltage is easy to be generated, resulting in that the workpiece 7 cannot complete the electric arc machining, and even the machining tool 3 and the workpiece 7 are damaged. Compared with the prior art, the machining device for the ceramic matrix composite material provided in the embodiment can compensate for the gap between the workpiece 7 and the machining tool 3 by increasing the soft conductive gasket 4 between the workpiece 7 and the machining tool 3, so as to ensure the adhesion of the workpiece 7 and the machining tool 3, avoid the generation of the gap voltage, and maintain the continuous discharge of the electric arc machining.

[0030] Based on the principle of electric arc machining, the electric arc machining needs to continuously strike and break the arc to avoid the phenomenon of excessive ablation of the surface of the workpiece 7. In order to achieve the effect, the electric arc machining of the ceramic matrix composite material is realized by adjusting the following two aspects during the electric arc machining of the workpiece 7.

[0031] On the one hand, the striking and breaking of the arc are realized by increasing the rotating speed of the electrode 2. For example, the rotating speed of the main shaft of the electrode 2 is 300-900 r / min.

[0032] In another aspect, the machining device further comprises a cooling water vapor supply unit 8 and a lateral water spraying unit 6, the electrode 2 is provided with a central hole 5 in the axial direction, one end of the central hole 5 is connected with the cooling water vapor supply unit 8, and the other end of the central hole 5 is directed towards the workpiece 7, and the water outlet of the lateral water spraying unit 6 is directed towards the contact surface between the electrode 2 and the workpiece 7.

[0033] It should be noted that the power supply 1 is a pulse power supply, the voltage of the pulse power supply is 22-28V, the frequency of the pulse power supply is 300-900Hz, and the duty cycle of the pulse power supply is 60%-90%.

[0034] Exemplarily, since the ceramic matrix composite material has high hardness and unstable electrical conductivity, the electrode 2 is a red copper electrode or a tungsten copper electrode. It should be noted that, in actual application, the tungsten copper electrode has a lower loss rate compared with the red copper electrode.

[0035] In order to be able to adjust the pose of the workpiece 7, the machining tooling 3 comprises a reference adjustment assembly, specifically comprising an XY-direction adjustment assembly and a Z-direction adjustment assembly, the XY-direction adjustment assembly is used for reference adjustment of the workpiece in the XY direction, and the Z-direction adjustment assembly is used for reference adjustment of the workpiece in the Z direction, wherein the X direction refers to the length direction of the workpiece, the Y direction refers to the width direction of the workpiece, and the Z direction refers to the thickness direction of the workpiece.

[0036] The XY-direction adjustment assembly comprises two groups of XY-direction adjustment supports and X-direction adjustment pins, Y-direction adjustment pins and Y-direction adjustment blocks, and the XY-direction adjustment supports are arranged on the bottom plate. The X-direction adjustment pins penetrate the XY-direction adjustment supports in the length direction of the workpiece and the relative positions of the X-direction adjustment pins and the XY-direction adjustment supports are adjustable (for example, by rotating the X-direction adjustment pins to adjust the length of the X-direction adjustment pins penetrating the XY-direction adjustment supports), the workpiece is located between the X-direction adjustment pins of the two groups of XY-direction adjustment assemblies, and the X-direction adjustment pins abut against the workpiece, and by adjusting the length of the X-direction adjustment pins penetrating the XY-direction adjustment supports at both ends of the workpiece, the relative position of the workpiece in the X direction can be adjusted; one end of the Y-direction adjustment block is fixedly connected with the XY-direction adjustment support, and the other end of the Y-direction adjustment block is a free end, the Y-direction adjustment pin penetrates the free end of the Y-direction adjustment block and the relative positions of the Y-direction adjustment pin and the Y-direction adjustment block are adjustable (for example, by rotating the Y-direction adjustment pin to adjust the length of the Y-direction adjustment pin penetrating the Y-direction adjustment block), the Y-direction adjustment pin abuts against the upper surface of the workpiece, and by adjusting the length of the Y-direction adjustment pin penetrating the Y-direction adjustment block, the relative position of the workpiece in the Y direction can be adjusted. In this way, the XY-direction adjustment assembly can realize the attitude alignment of the workpiece in the length direction and the width direction.

[0037] Similarly, the number of Z-direction adjustment assemblies is multiple, each including a Z-direction adjustment support and multiple Z-direction adjustment pins. The Z-direction adjustment support has a fork-shaped cross section, including a connecting seat and two fork walls provided at the top end of the connecting seat. The two fork walls have a gap therebetween. A part of the Z-direction adjustment pins penetrate one of the fork walls in the thickness direction of the workpiece and abut against the workpiece. Another part of the Z-direction adjustment pins penetrate the other fork wall in the thickness direction of the workpiece and abut against the workpiece. When the Z-direction posture of the workpiece needs to be adjusted, the lengths of the multiple Z-direction adjustment pins penetrating the fork walls are adjusted respectively, so that the Z-direction posture of the workpiece can be adjusted.

[0038] Embodiment Two

[0039] The embodiment provides a machining method for a ceramic matrix composite material, and the machining method comprises the following steps:

[0040] Step 1: polishing the surface of the workpiece 7 of the ceramic matrix composite material until the continuous coating of silicon carbide is removed or the continuous coating of silicon carbide at the position corresponding to the machining tool in the electric arc machining process is removed, and part of the carbon fibers is exposed.

[0041] Step 2: placing the workpiece 7 in the machining tool 3, and placing the soft conductive gasket 4 (for example, a soft copper gasket) between the workpiece 7 and the machining tool 3, so that the machining tool 3 clamps the workpiece 7, and there is no gap between the machining tool 3 and the soft conductive gasket 4 and between the soft conductive gasket 4 and the workpiece 7.

[0042] Step 3: coarsely machining the workpiece 7 by using the electric arc machining method.

[0043] Step 4: finely machining the workpiece 7 after the coarse machining to the final part size by using the ultrasonic vibration auxiliary machining method.

[0044] Compared with the prior art, the machining method for the ceramic matrix composite material has basically the same beneficial effects as the machining device for the ceramic matrix composite material, and details are not described herein.

[0045] In addition, the above processing method is a high-efficiency and low-damage processing method. On the one hand, the processing method combines arc processing and ultrasonic vibration assisted processing. First, the arc processing method is used for rough machining, which can remove material with high energy and high efficiency. However, the surface roughness of the workpiece 7 is poor, and the recast layer affects the strength of the ceramic matrix composite material. Then, the ultrasonic vibration assisted processing method is used for finishing machining to remove defects such as recast layer and crack generated by arc processing. The ultrasonic vibration assisted processing can generate a cutting force which is 1 / 3 to 1 / 2 smaller than that of conventional milling, which is beneficial to control the surface quality of the workpiece 7 and ensure the machining accuracy of the plane, so that the size of the workpiece 7 is in place and the size accuracy of the final part is ensured. At the same time, it meets the requirements of high efficiency and low damage processing of ceramic matrix composite materials. In practical application, the machining surface accuracy error of the ceramic matrix composite workpiece 7 obtained by using the above processing method is less than or equal to 0.2 mm, the parallelism is 0.1 mm, the perpendicularity is 0.1 mm, and the flatness is 0.05 mm. Basically, there are no defects such as recast layer and crack generated by machining.

[0046] On the other hand, the workpiece 7 is pretreated before clamping, and the continuous coating of silicon carbide is removed or the continuous coating of silicon carbide at the position corresponding to the machining tool in the arc machining process is removed, so that part of the carbon fiber is exposed. This can effectively improve the conductivity of the workpiece 7 during arc machining.

[0047] Specifically, the above step 3 includes the following steps:

[0048] Step 31: install the electrode 2 on the tool holder, connect the workpiece 7 with the positive electrode of the power supply 1, and connect the electrode 2 with the negative electrode of the power supply 1.

[0049] Step 32: turn on the power supply 1, and the bottom and side of the electrode 2 discharge, and the electrode 2 rotates to rough machine the workpiece 7 to achieve the effect of etching.

[0050] In order to ensure the machining amount and efficiency, the rough machining size is one step to place, and in the above step 32, the feed speed of the electrode 2 is 1-2 mm / min, and the cutting depth is 2-4 mm. In this way, through arc machining with large cutting depth, the machining efficiency can be improved by more than 3 times compared with the traditional machining method.

[0051] Based on the principle of arc machining, arc machining needs to constantly arc and break arc to avoid the phenomenon of excessive ablation of the surface of the workpiece 7. In order to achieve the effect, during the turning process of the workpiece 7, the arc machining of the ceramic matrix composite material is realized by adjusting from the following two aspects.

[0052] On the one hand, the arc and break arc are realized by increasing the speed of the electrode 2. For example, in the above step 32, the spindle speed of the electrode 2 is 300-900 r / min.

[0053] On the other hand, the arc striking and arc breaking are realized by spraying water cooling during the arc machining, specifically, the spraying water cooling comprises the following steps:

[0054] The high-pressure water vapor is sprayed from the center hole 5 of the electrode 2 to perform the center spraying water cooling;

[0055] The high-pressure water vapor is sprayed to the contact surface between the electrode 2 and the workpiece 7 to perform the side spraying water cooling.

[0056] Considering that the surface roughness Sz is usually used to describe the peak-to-valley height difference of the ceramic matrix composite surface, the surface roughness Sz is taken as a reference index, and based on the process parameters of the arc machining, the surface roughness Sz of the arc machining is 100-350 μm, and the thickness of the recast layer defect generated by the arc machining is 30-50 μm. By comprehensively considering the two factors of the surface roughness Sz and the thickness of the recast layer defect, the reserved allowance after the arc machining is 0.4-0.5 mm.

[0057] In order to effectively control the machining quality of the ultrasonic vibration assisted machining, in the above step 4, the machining parameters of high rotation speed and small cutting depth are adopted, the center working frequency of the ultrasonic vibration is 16-24 KHz (for example, 20 KHz), the amplitude is 2-6 μm (for example, 4 μm), the rotation speed is 2000-10000 r / min, the feed speed is 20-100 mm / min, the cutting machining depth is 0.1-0.5 mm, and the tool is a diamond milling and grinding head, so as to ensure the machining precision and the surface quality.

[0058] In order to be able to carry out the multi-energy field machining with more preferred process parameters, the above step 1 further comprises the following steps:

[0059] A plurality of test blanks are provided, and the plurality of test blanks are subjected to multi-energy field machining by using different multi-energy field process parameters to obtain a plurality of test workpieces;

[0060] The comprehensive damage evaluation factor of each test workpiece is calculated;

[0061] The multi-energy field process parameters corresponding to the minimum value of the plurality of comprehensive damage evaluation factors are the optimal process parameters;

[0062] The optimal process parameters are used as the multi-energy field machining process parameters of the workpiece 7.

[0063] Specifically, the calculation of the comprehensive damage evaluation factor is based on the microscopic observation of the surface of the machined workpiece by taking the machining defects such as cracks, fiber debonding, fiber pull-out and recast layer as observation indexes, and the weight analysis of different damages, which comprises the following steps:

[0064] Step I: The surface of the test workpiece is divided into a plurality of test workpiece regions;

[0065] Step II: Obtain the damage parameters of the processed test workpiece, including damage location, damage type, damage size (i.e. length and width) and recast layer thickness;

[0066] Step III: Count the damage parameters of the processed test workpiece in each test workpiece area under the same magnification (e.g. 1000 times) using a scanning electron microscope, and obtain a defect data table;

[0067] Step IV: Calculate the crack damage evaluation factor, fiber debonding damage evaluation factor and fiber pull-out damage evaluation factor in each test workpiece area;

[0068] The calculation formula of the crack damage evaluation factor is as follows:

[0069] F a = N a / S

[0070] In the formula, F a is the crack damage evaluation factor, N a is the number of crack damages in the test workpiece area, and S is the area of the test workpiece area.

[0071] The calculation formula of the fiber debonding damage evaluation factor is as follows:

[0072] F b = N b / S

[0073] In the formula, F b is the fiber debonding damage evaluation factor, N b is the number of fiber debonding damages in the test workpiece area, and S is the area of the test workpiece area.

[0074] The calculation formula of the fiber pull-out damage evaluation factor is as follows:

[0075] F c = N c / S

[0076] In the formula, F c is the fiber pull-out damage evaluation factor, N c is the number of fiber pull-out damages in the test workpiece area, and S is the area of the test workpiece area.

[0077] Step V: Calculate the area damage evaluation factor according to the crack damage evaluation factor, fiber debonding damage evaluation factor, fiber pull-out damage evaluation factor and recast layer thickness, and the calculation formula of the area damage evaluation factor is as follows:

[0078] P = l1F a + l2F b + l3F c + l4Fh

[0079] In the formula, P is the area damage evaluation factor, l1 is the crack damage weight, F a is the crack damage evaluation factor, l2 is the fiber debonding damage weight, F b is the fiber debonding damage evaluation factor, l3 is the fiber pull-out damage weight, F c is the fiber pull-out damage evaluation factor, l4 is the recast layer damage weight, F c is one-tenth of the recast layer thickness.

[0080] Wherein, l1+l2+l3+l4=1, l1 is 0.2-0.5, l2 is 0.1-0.2, l3 is 0.1-0.2, and l4 is 0.3-0.5.

[0081] It should be noted that due to the difference in the thermal expansion coefficient between the carbon fiber and the SiC matrix, after rapid cooling, the thermal stress inside the carbon fiber is large, and the expansion makes the external SiC fiber prone to crack, leading to the formation of fiber debonding. When the fiber debonding further expands, the fiber pull-out phenomenon occurs. Similarly, due to the structural characteristics of the loose and porous recast layer and the existence of internal microcracks, the surface quality and service performance of the fiber-reinforced silicon carbide material will be greatly affected. Therefore, greater evaluation coefficients are given to cracks and recast layers during damage evaluation, i.e. l1+l4≥0.5.

[0082] Step VI: Calculate the sum of the area damage evaluation factors of the multiple test workpiece regions divided by the number of test workpiece regions to obtain the comprehensive damage evaluation factor.

[0083] The above calculation method of the comprehensive damage evaluation factor analyzes the damage mechanism. The damage is mainly affected by the cutting force of mechanical machining, the thermal stress of electric arc machining, and the expansion coefficient of carbon fiber. In view of the anisotropy and complex weaving structure characteristics of high-temperature resistant fiber-reinforced silicon carbide composite materials, the machining damage of different defect characteristics in different regions of the machined test workpiece surface is observed and statistically analyzed.

[0084] In order to obtain accurate damage location, damage type and damage size, in the above step II, obtaining the damage location, damage type and damage size of the machined test workpiece includes the following steps:

[0085] Using a low magnification (e.g., magnification of 100-500 times) of a scanning electron microscope, the overall morphology of the surface of the machined test workpiece is observed to determine the damage location of the workpiece surface in each test workpiece region;

[0086] The damage morphology of the damage position is observed by using a scanning electron microscope with a medium magnification (for example, a magnification of 1000-2000 times), the damage type is determined, statistical analysis is performed, and the number of cracks, fiber debonding, and fiber pull-out in each test workpiece region is obtained.

[0087] The damage size in each test workpiece region is obtained by using a scanning electron microscope with a high magnification (for example, a magnification of 5000-20000 times).

[0088] Similarly, in order to obtain an accurate recast layer thickness, in step I above, the recast layer thickness can be obtained in the following manner.

[0089] One way includes the following steps:

[0090] Step a: the machined test workpiece is cut along the thickness direction;

[0091] Step b: energy spectrum analysis of the machined test workpiece cross-section is performed by using a scanning electron microscope, and the oxygen element content of the machined test workpiece cross-section is obtained;

[0092] Step c: a thickness-oxygen element content spectrum is drawn, and the thickness of the recast layer is determined according to the position where the oxygen element fluctuates.

[0093] Another way includes the following steps:

[0094] Step a': the machined test workpiece is cut along the thickness direction;

[0095] Step b': phase analysis of the machined test workpiece cross-section is performed by using an X-ray diffractometer, and a phase diagram of the oxide is obtained;

[0096] Step c': the thickness of the recast layer is determined according to the content change of the oxide in the phase diagram.

[0097] It is worth noting that, for the damage of the machined test workpiece, part of it is the damage of the raw material itself, and the other part is the machining damage. In order to improve the accuracy of the machining damage evaluation, the following steps are further included before step 1 above:

[0098] The damage parameters of the workpiece blank are obtained, including the damage position, damage type, and damage size (i.e., length and width).

[0099] The following steps are further included between step II and step III above:

[0100] Subtract the same damage parameters from the damage parameters of the workpiece after processing to obtain the corrected damage parameters, which include new damage generated in the actual processing and damage expanded in the processing, and use the corrected damage parameters as the damage parameters in step 3.

[0101] In this way, by correcting the damage parameters of the workpiece after processing by using the damage parameters of the workpiece blank, the new damage generated in the actual processing and the damage expanded in the processing can be obtained, the influence of the original damage of the workpiece blank on the processing damage evaluation is reduced, and the accuracy of the processing damage evaluation is further improved.

[0102] In order to obtain the accurate damage position, damage type and damage size of the workpiece blank, the damage parameters of the workpiece blank include the following steps:

[0103] Step A: divide the surface of the workpiece blank into a plurality of blank areas, and the blank areas correspond to the positions of the workpiece areas;

[0104] Step B: use low magnification (for example, magnification of 100-500 times) of a scanning electron microscope to observe the overall morphology of the surface of the workpiece blank, and determine the damage position of the blank surface in each blank area;

[0105] Step C: use medium magnification (for example, magnification of 1000-2000 times) of a scanning electron microscope to observe the damage morphology characteristics of the damage position, determine the damage type, perform statistical analysis, and obtain the number of cracks, fiber debonding and fiber pull-out in each blank area;

[0106] Step D: use high magnification (for example, magnification of 5000-20000 times) of a scanning electron microscope to obtain the damage size in each blank area.

[0107] The above only describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, any changes or replacements within the technical range disclosed by the present application can be easily thought by those skilled in the art, which should be covered within the protection scope of the present application.

Claims

1. A machining device for a ceramic matrix composite material, characterized in that, Includes an electric arc machining unit and an ultrasonic vibration-assisted machining unit; The arc processing unit includes a power supply, an electrode, a processing fixture, and a soft conductive pad. The workpiece made of ceramic matrix composite material is connected to the positive terminal of the power supply, and the electrode is connected to the negative terminal of the power supply. A groove is formed on the upper surface of the processing fixture, and the soft conductive pad is placed between the side wall of the workpiece and the groove wall, so that the workpiece is suspended in the groove. The ultrasonic vibration-assisted processing unit includes a milling head and an ultrasonic vibration generator for driving the ultrasonic vibration of the milling head; the soft conductive pad is a soft copper pad. The machining fixture includes a reference adjustment assembly, which includes an XY-axis adjustment assembly and a Z-axis adjustment assembly. There are two sets of XY-axis adjustment assemblies, which are respectively located at both ends of the workpiece and arranged opposite to each other. Each XY-axis adjustment assembly includes an XY-axis adjustment support, an X-axis adjustment pin, a Y-axis adjustment pin, and a Y-axis adjustment pressure block. The X-axis adjustment pin passes through the XY-axis adjustment support along the length of the workpiece. The workpiece is located between the X-axis adjustment pins of the two sets of XY-axis adjustment assemblies, and the X-axis adjustment pins abut against the workpiece. One end of the Y-direction adjusting block is fixedly connected to the XY-direction adjusting support, and the other end of the Y-direction adjusting block is a suspended end. The Y-direction adjusting pin passes through the suspended end of the Y-direction adjusting block and abuts against the upper surface of the workpiece. The Z-axis adjustment components are in multiple sets, each including a Z-axis adjustment support and multiple Z-axis adjustment pins. The Z-axis adjustment support has a fork-shaped cross-section and includes a connecting seat and two fork walls located at the top of the connecting seat. A portion of the Z-axis adjustment pins penetrates one of the fork walls along the thickness direction of the workpiece and then abuts against the workpiece. Another portion of the Z-axis adjustment pins penetrates the other fork wall along the thickness direction of the workpiece and then abuts against the workpiece.

2. The machining device for a ceramic matrix composite according to claim 1, characterized by, It also includes a cooling water vapor supply unit, wherein the electrode has a central hole along the axial direction, one end of the central hole is connected to the cooling water vapor supply unit, and the other end of the central hole faces the workpiece.

3. The machining device for a ceramic matrix composite according to claim 2, characterized by It also includes a side spray water unit, the outlet of which faces the contact surface between the electrode and the workpiece.

4. The machining apparatus for a ceramic matrix composite according to claim 1, characterized by, The spindle speed of the electrode is 300~900 r / min.

5. The machining apparatus for a ceramic matrix composite material according to Claim 1, characterized by The milling head is a diamond milling head.

6. The machining apparatus for a ceramic matrix composite according to claim 1, characterized by, The power supply is a pulse power supply.

7. The machining device for a ceramic matrix composite according to claim 6, characterized by The voltage of the pulse power supply is 22~28V, the frequency of the pulse power supply is 300~900Hz, and the duty cycle of the pulse power supply is 60%~90%.

8. The machining apparatus for a ceramic matrix composite according to claim 1, characterized by, The electrode is a copper electrode or a tungsten-copper electrode.

9. A method for machining of a ceramic matrix composite material, characterized in that The processing apparatus for ceramic matrix composites as described in any one of claims 1 to 8 is used.

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