SiCf / SiC ceramic matrix composite flame tube and outer molded surface processing method

Abstract

The invention relates to the technical field of ceramic matrix composite material grinding machining, in particular to a SiCf / SiC ceramic matrix composite material flame tube and an outer profile machining method. The machining radius and profile tolerance requirements of the outer profile of a workpiece on the inner wall or the outer wall of the flame tube, the grinding machining rotation indexing angle and the diameter of a grinding tool grinding head are obtained; according to the diameter of a grinding tool grinding head, a proper grinding tool is selected to conduct ultrasonic vibration auxiliary grinding machining on the outer profile of a flame tube inner or outer wall workpiece. Through the matching design of the rotating indexing angle and the diameter of the grinding head of the grinding tool, self-adaptive optimization of technological parameters is achieved, the efficiency and precision are balanced, the profile tolerance of a machined profile is ensured, the machining quality and the machining efficiency are improved, meanwhile, ultrasonic vibration is adopted for assisting grinding tool path optimization grinding machining, the machining quality can be improved, and the machining cost is reduced. And the service life of the cutter can be prolonged, and the problem that the machining efficiency of the outer surface of the flame tube of the combustion chamber made of the existing SiCf / SiC ceramic matrix composite is low is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of grinding processing of ceramic matrix composites, and specifically to a method for machining a SiC f / SiC ceramic matrix composite flame tube and its external profile. Background Art

[0002] Silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC f / SiC) is mainly composed of silicon carbide fibers and a silicon carbide matrix, and has the characteristics of low density, high temperature resistance, and high hardness, and has broad application prospects in the field of hot-end components of advanced aero-engines. However, the high hardness, brittleness, and material inhomogeneity of SiC f / SiC ceramic matrix composites make it face problems such as large tool wear, difficult machining, and poor machinability in machining.

[0003] Chinese invention with publication number CN117102982A discloses "a method for ultrasonic vibration assisted grinding of ceramic matrix composites". This method obtains the critical depth of micro-macro brittle fracture transition through single-grit basic scratching tests; then based on the critical depth of micro-macro brittle fracture transition and the surface quality of the machined part, the ultrasonic vibration assisted grinding process parameters are obtained; finally, based on the ultrasonic vibration assisted grinding process parameters, ultrasonic vibration assisted grinding of ceramic matrix composites is carried out, achieving an improvement in grinding efficiency while ensuring high-quality surface machining of ceramic matrix composites. However, in the field of aero-engines, the inner and outer wall dimensions and shapes of the combustion chamber flame tube of SiC f / SiC ceramic matrix composites that require high temperature resistance need to match the engine and be lightweight. The ring-shaped thin-wall structure is adopted, and conventional turning or grinding is used for machining the inner and outer wall external profiles. The tool is extremely easy to wear, and the surface quality after machining is poor and the machining efficiency is low; if only the above method of single-grit basic scratching test combined with ultrasonic vibration assisted grinding is used, although the machining quality and efficiency are improved to some extent, the problems of grinding head wear and low machining efficiency still cannot be overcome. Summary of the Invention

[0004] Aiming at the problem of low machining efficiency of the external profile of the combustion chamber flame tube of SiC f / SiC ceramic matrix composites in the prior art, the present invention provides a method for machining a SiC f / SiC ceramic matrix composite flame tube and its external profile.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for machining the external profile of a SiC f / SiC ceramic matrix composite flame tube, including: Obtain the machining radius and the profile tolerance requirements of the outer or inner wall workpiece of the combustion chamber liner; According to the machining radius and the profile tolerance requirements of the outer or inner wall workpiece of the combustion chamber liner, obtain the rotational indexing angle for grinding; Determine the diameter of the grinding tool's grinding head according to the rotational indexing angle for grinding; Select a suitable grinding tool according to the diameter of the grinding tool's grinding head, and perform ultrasonic vibration assisted grinding on the outer or inner wall workpiece of the combustion chamber liner.

[0006] Optionally, the axis of the grinding tool is perpendicular to the axis of the outer or inner wall workpiece of the combustion chamber liner.

[0007] Optionally, the method for obtaining the rotational indexing angle for grinding according to the machining radius and the profile tolerance requirements of the outer or inner wall workpiece of the combustion chamber liner is as follows: cos(α / 2)=R / (R+H) F≤H≤F Where, α is the rotational indexing angle for grinding; R is the machining radius of the outer or inner wall workpiece of the combustion chamber liner; F is the 1 / 2 profile tolerance value of the outer or inner wall workpiece of the combustion chamber liner.

[0008] Optionally, the method for determining the diameter of the grinding tool's grinding head according to the rotational indexing angle for grinding is as follows: ΦC=2×(A+B) A=tan(α / 2)×R Where, ΦC is the diameter of the grinding tool's grinding head; 3mm≤B≤6mm; α is the rotational indexing angle for grinding; R is the machining radius of the outer or inner wall workpiece of the combustion chamber liner.

[0009] Optionally, the grinding head of the grinding tool is a brazed diamond grinding head.

[0010] Optionally, the particle size of the diamond abrasive grains on the brazed diamond grinding head is 150 - 250 mesh.

[0011] Optionally, the value of the rotational indexing angle for grinding is divisible by 360°.

[0012] Optionally, the grinding tool includes a clamping portion, and the diameter ΦD of the clamping portion satisfies: 6mm≤ΦD≤M(mm), where M is the maximum clamping diameter of the ultrasonic vibration grinding tool shank.

[0013] Optionally, the grinding speed of the ultrasonic vibration assisted grinding is 6000 - 11000 rpm / min, the feed speed is 1000 - 1500 mm / min, and the grinding depth is 0.05 - 0.1 mm; the frequency of the ultrasonic vibration is 28 - 38 kHz; the amplitude of the grinding head of the grinding tool is 4 - 8um.

[0014] The present invention also provides a SiC f / SiC ceramic matrix composite flame tube, which is processed by the above-mentioned external surface processing method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: A SiC of the present invention f / SiC ceramic matrix composite flame tube and an external surface processing method. The method includes obtaining the processing radius and the profile tolerance requirements of the external surface of the workpiece on the inner or outer wall of the flame tube; then, according to the processing radius and the profile tolerance requirements of the external surface of the workpiece on the inner or outer wall of the flame tube, obtaining the rotational indexing angle for grinding; finally, according to the rotational indexing angle for grinding, determining the diameter of the grinding tool bit, and selecting a grinding tool according to the diameter of the grinding tool bit to perform ultrasonic vibration assisted grinding on the external surface of the workpiece on the inner or outer wall of the flame tube. Through the matching design of the rotational indexing angle and the diameter of the grinding tool bit, the adaptive optimization of process parameters is realized, the efficiency and precision are balanced, the profile tolerance of the processed surface is ensured, so as to meet the high-precision processing requirements of complex surfaces, improve the processing quality and processing efficiency, and avoid tool overload or ineffective processing caused by parameter mismatch; at the same time, ultrasonic vibration assisted grinding tool path is adopted to optimize grinding, which can not only reduce damages such as material microcracks and chipping, improve surface integrity, but also reduce the grinding force and grinding heat during the grinding process, reduce the continuous contact between the grinding tool and the workpiece, reduce the wear of the grinding head, extend the service life, reduce the tool change frequency and processing cost. This method is simple and easy to operate, can be integrated into a numerical control machine tool, has strong compatibility, is suitable for batch production, and provides key technical support for the engineering application of advanced ceramic matrix composites.

[0016] The axis of the grinding tool is perpendicular to the axis of the workpiece on the inner or outer wall of the flame tube. When the tool axis is perpendicular to the workpiece axis, the grinding force mainly acts along the normal direction of the workpiece surface, avoiding tool slip or offset caused by the lateral component force, thus significantly improving the profile accuracy and dimensional consistency of the surface; at the same time, vertical grinding makes the force on the contact area between the abrasive grains and the workpiece uniform, reducing fiber fracture, matrix spalling or microcrack propagation caused by local stress concentration, especially suitable for high surface integrity processing of brittle SiC f / SiC materials.

[0017] The method for obtaining the rotational indexing angle for grinding according to the processing radius and the profile tolerance requirements of the external surface of the workpiece on the inner or outer wall of the flame tube is based on the arc envelope theory combined with the limitation of the residual height, directly converting the surface profile into the geometric constraints for the grinding tool path planning, strictly binding the calculation of the indexing angle with the precision requirements, and limiting the radial deviation of the covered area between two adjacent machining operations of the grinding tool within the required range, so as to ensure the stable quality of the final surface profile.

[0018] The method for determining the diameter of the grinding tool's grinding head based on the rotational indexing angle in grinding operations determines the diameter of the grinding tool's grinding head through the rotational indexing angle in grinding operations, and introduces a redundancy amount to ensure that even if there are minor deviations in theoretical calculations, the error can still be covered by the compensation amount, ensuring that the actual overlap amount between adjacent grinding trajectories always meets the design requirements and avoiding stripe defects in the surface residual unprocessed area caused by insufficient overlap.

[0019] The grinding head of the grinding tool is a brazed diamond grinding head. The brazed diamond grinding head has better wear resistance and a longer service life. The brazed diamond abrasive grains have a high protrusion height, and the binder has less wrapping around the abrasive grains, keeping the grinding edges of the abrasive grains always sharp, reducing the grinding force, and reducing the transverse shear damage to SiC f / SiC fibers and the propagation of matrix microcracks.

[0020] The particle size of the diamond abrasive grains on the brazed diamond grinding head is 150 - 250 mesh. The particle size of the abrasive grains is moderate, and the cutting depth and grinding volume of a single abrasive grain are reasonable, which can not only ensure a high material removal rate but also avoid deep grooves or surface chipping caused by too coarse abrasive grains, and is especially suitable for the efficient processing of SiC f / SiC.

[0021] The value of the rotational indexing angle in grinding operations can be divided evenly by 360°. When the rotational indexing angle in grinding operations is divisible by 360°, it can enable the grinding tool to cover the entire circumference of the outer or inner wall workpiece profile of the combustion chamber during processing, ensuring that the starting point and the ending point of each indexing strictly coincide, avoiding surface ripples or overcutting of materials caused by overlapping grinding, and thus avoiding unprocessed or reprocessed areas caused by angular cumulative errors, and ensuring the uniformity and accuracy of processing.

[0022] The grinding tool includes a clamping part, and the diameter ΦD of the clamping part satisfies: 6mm ≤ ΦD ≤ M (mm), where M is the maximum clamping diameter of the ultrasonic vibration grinding tool shank, making the grinding tool more compatible with the processing equipment and ensuring the stability of processing and the energy transfer efficiency.

[0023] The grinding speed in the ultrasonic vibration-assisted grinding process is 6000 - 11000 rpm / min, the feed rate is 1000 - 1500 mm / min, and the grinding depth is 0.05 - 0.1 mm; the frequency of the ultrasonic vibration is 28 - 38 kHz; the amplitude of the grinding head of the grinding tool is 4 - 8 μm. The appropriate grinding speed, feed rate, grinding depth, and frequency of the ultrasonic vibration, combined with the precise grinding path and parameter settings of the grinding tool, ensure the processing quality while improving the processing efficiency. Compared with the traditional processing method, the efficiency is increased by 500%, and at the same time, the tool cost is reduced, achieving the processing of SiC fThe efficient and high-quality grinding of the inner or outer wall workpiece surface of the SiC / SiC ceramic matrix composite flame tube has promoted the breakthrough of the precision machining technology of ceramic matrix composite components, laying a certain technical foundation for promoting the engineering application of ceramic matrix composites.

[0024] A kind of SiC f / SiC ceramic matrix composite flame tube, processed by the above-mentioned outer surface processing method, this SiC f / SiC ceramic matrix composite flame tube has the characteristics of high-temperature stability, lightweight, high strength, efficient cooling and long life, providing key technical support for the high performance, high reliability and long life of aero-engines. Brief Description of the Drawings

[0025] Figure 1 It is a schematic flow chart of a method for machining the outer surface of a SiC f / SiC ceramic matrix composite flame tube according to the present invention.

[0026] Figure 2 It is a schematic diagram of the feed path and the relationship between the grinding tool structure during the process of a method for machining the outer surface of a SiC f / SiC ceramic matrix composite flame tube according to the present invention.

[0027] Figure 3 It is a schematic diagram of the structural shape of the inner wall workpiece of a certain flame tube.

[0028] Figure 4 It is a schematic diagram of the feed path and the relationship between the grinding tool structure in a specific embodiment of the present invention.

[0029] Among them, 1 - grinding tool, 2 - inner or outer wall workpiece of the flame tube. Detailed Embodiments

[0030] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification, claims and the above drawings of the present invention are used to distinguish similar objects and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0032] The following further elaborates on the present invention with specific embodiments, which is an explanation rather than a limitation of the present invention.

[0033] In the field of aeroengines, the inner or outer wall dimensions and shape of the combustion chamber flame tube of SiC f / SiC ceramic matrix composite materials are required to match the engine and be lightweight. It adopts an annular thin-wall structure. The machining of the inner or outer wall profile uses conventional turning or grinding. The cutting tools are extremely prone to wear, the surface quality after machining is poor, and the machining efficiency is low.

[0034] To solve the above problems, see Figure 1 , the present invention discloses a method for machining the outer profile of a SiC f / SiC ceramic matrix composite flame tube, including: S1: Obtain the machining radius and profile tolerance requirements of the outer profile of the inner or outer wall workpiece 2 of the flame tube, specifically: By analyzing the structural characteristics and machining requirements of the outer profile of the inner or outer wall workpiece 2 of the SiC f / SiC ceramic matrix composite flame tube, select a suitable machining center. For example, the outer wall of a certain flame tube is an annular thin-wall structure, and the machining requirements are that the surface roughness Ra of the machined surface ≤ 3.2um, the profile tolerance ≤ 0.3mm, and there are no micro-cracks, tears, chipping, and delamination phenomena on the grinding surface.

[0035] S2: According to the machining radius and profile tolerance requirements of the outer profile of the inner or outer wall workpiece 2 of the flame tube, obtain the rotational indexing angle for grinding, specifically: cos(α / 2)=R / (R+H) (1 / 6)F≤H≤(1 / 4)F where α is the rotational indexing angle for grinding; R is the machining radius of the outer profile of the inner or outer wall workpiece 2 of the flame tube; F is the 1 / 2 profile tolerance value of the inner or outer wall workpiece 2 of the flame tube; preferably, the value of the rotational indexing angle for grinding can be divisible by 360°; S3: Determine the diameter of the grinding head of the grinding tool 1 according to the rotational indexing angle of the grinding process, specifically: ΦC = 2×(A + B) A = tan(α / 2)×R Where, ΦC is the diameter of the grinding head of the grinding tool 1; 3mm ≤ B ≤ 6mm; α is the rotational indexing angle of the grinding process; R is the machining radius of the outer or inner wall workpiece 2 of the combustion chamber liner.

[0036] Preferably, the axis of the grinding tool 1 is perpendicular to the axis of the outer or inner wall workpiece 2 of the combustion chamber liner; the grinding head of the grinding tool 1 is a brazed diamond grinding head, and the grain size of the diamond abrasive is 150 - 250 mesh. The grinding tool 1 includes a clamping part, and the diameter ΦD of the clamping part satisfies: 6mm ≤ ΦD ≤ M (mm), where M is the maximum clamping diameter of the ultrasonic vibration grinding tool shank.

[0037] See Figure 2 , after determining the feed path and the structural parameters of the grinding tool through S1 - S3, perform the machining in the manner shown in the figure. Based on the single - grain scratch test of SiC f / SiC ceramic matrix composite, analyze the material removal fracture form and the material removal mechanism, and combine with the ultrasonic vibration - assisted grinding process test of SiC f / SiC ceramic matrix composite to determine the grinding process parameters, and conduct geometric simulation on the grinding process.

[0038] S4: Select the grinding tool 1 to perform ultrasonic vibration - assisted grinding on the outer profile of the outer or inner wall workpiece 2 of the combustion chamber liner according to the diameter of the grinding head of the grinding tool 1, specifically: Operate the machining center, and assemble and connect the ultrasonic vibration - assisted grinding device to the machining center. Correctly install and fix the special tooling on the workbench of the machining center, and then correctly position and clamp the inner or outer wall workpiece of SiC f / SiC ceramic matrix composite on the special tooling, and adjust and place it in the machining position.

[0039] Select the cooling method during the machining process as water - based grinding fluid cooling for the outer profile grinding of the inner or outer wall workpiece 2 of SiC f / SiC ceramic matrix composite.

[0040] Operate the equipment to perform the outer profile grinding of the inner or outer wall workpiece 2 of SiC f / SiC ceramic matrix composite; According to the determined structural parameters of the grinding tool, select the correct diamond grinding head and install it on the ultrasonic grinding tool shank.

[0041] Turn on the power of the ultrasonic vibration assisted grinding device. The frequency selection range of ultrasonic vibration is 28 - 38 kHz. Test the vibration state of the ultrasonic vibration device and detect the vibration amplitude of the grinding head. The vibration amplitude is controlled within 4 - 8 μm; the grinding speed is 6000 - 11000 rpm / min, the feed speed is 1000 - 1500 mm / min, and the grinding depth is 0.05 - 0.1 mm; Operate the machining center, set parameters, call the program, and complete the profile grinding.

[0042] After completing the inner wall profile grinding, turn off the power of the ultrasonic vibration assisted grinding system.

[0043] A kind of SiC f / SiC ceramic matrix composite flame tube, processed by the above external profile processing method. This SiC f / SiC ceramic matrix composite flame tube has the characteristics of high temperature stability, lightweight, high strength, efficient cooling and long life, etc., providing key technical support for the high performance, high reliability and long life of aero - engines.

[0044] Example 1 To further illustrate the technical solution of the present invention, see Figure 3 , which is a schematic diagram of the shape of the inner wall workpiece 2 of a certain flame tube. The structural feature is an annular thin - walled structure with taper, and the wall thickness is 2.2 mm; after analysis of the structural features and processing requirements of the external profile of the inner wall test piece of the SiC f / SiC ceramic matrix composite flame tube, select the KMC800S - UMT turning - milling composite machining center as the grinding equipment. Processing requirements: the surface roughness of the processed surface ≤ Ra3.2 μm, the profile tolerance of the profile ≤ 0.3 mm, and there are no micro - cracks, tears, chips, and delamination phenomena on the grinding surface.

[0045] See Figure 4 , determine that the axis of the grinding tool is perpendicular to the axis of the inner wall workpiece 2 of the flame tube, and use the end face of the grinding tool 1 to grind the profile of the inner wall workpiece 2 of the flame tube.

[0046] According to the outer - circle profile machining radius of the inner wall workpiece 2 of the flame tube and the profile tolerance requirements, determine the grinding machining rotation indexing angle α.

[0047] It is known that the outer - circle machining radius of the inner wall workpiece 2 of the flame tube is R = 204 mm, and the value of 1 / 2 profile tolerance is F ≤ 0.15 mm.

[0048] According to the range of H value as F ≤ H ≤ F, that is, 0.025 mm ≤ H ≤ 0.0375 mm.

[0049] Using cos(α / 2)=R / (R+H), calculate that the rotational indexing angle α for grinding satisfies 1.79°≤α≤2.197°, and the degree of α that can be divisible by 360︒ is taken as 2°; According to ΦC=2×(A+B), where: A = tan(α / 2)×R, 4mm≤B≤8mm, A = 3.56mm, take B = 6.44mm, and determine that the diameter of the grinding head of the grinding tool 1 is 20mm; In order to be able to assemble and connect with the ultrasonic tool holder and maintain a certain rigidity of the grinding tool 1, determine that the diameter ΦD of the clamping part of the grinding tool 1 is 10mm.

[0050] Select the grinding tool material: Select a brazed diamond grinding head, and the particle size of the diamond abrasive grains on the grinding head is 180 mesh.

[0051] Determine the grinding parameters: rotational speed n = 7000rpm / min; feed rate f = 1200mm / min; grinding depth ap = 0.08mm, and perform geometric simulation on the grinding process.

[0052] Operate the machining center to assemble and connect the ultrasonic vibration-assisted grinding device with the KMC800S-UMT turning and milling compound machining center. Correctly install and fix the special tooling on the machining center workbench, and then correctly position and clamp the inner wall workpiece of the SiC f / SiC ceramic matrix composite on the special tooling, and adjust and place it in the machining position.

[0053] Select the cooling method: During the grinding process of the outer cylindrical surface of the inner wall of the SiC f / SiC ceramic matrix composite, water-based grinding fluid is used for cooling.

[0054] Operate the equipment to perform the grinding of the outer cylindrical surface of the inner wall of the SiC f / SiC ceramic matrix composite, specifically: 1) Install the selected diamond grinding head on the ultrasonic grinding tool holder.

[0055] 2) Turn on the power of the ultrasonic vibration-assisted grinding device, and adjust the frequency of the ultrasonic vibration to 30kHz. Test the vibration state of the ultrasonic vibration device and the vibration amplitude of the grinding head of the grinding tool 1, and keep the amplitude at 4μm by adjusting the tool overhang.

[0056] 4) Operate the machining center, set the parameters, call the program, and complete the profile grinding.

[0057] 5) After completing the profile grinding of the inner wall workpiece 2 of the flame tube, turn off the power of the ultrasonic vibration-assisted grinding system.

[0058] In this embodiment, analyze the SiC fBased on the structural characteristics and machining requirements of the inner wall profile of the SiC / SiC ceramic matrix composite flame tube, the KMC800S-UMT turning and milling compound machining center was selected, the tool path was reasonably planned, and the grinding tool 2 was determined. The process parameters were adopted: spindle speed 7000 r / min, feed speed 1200 mm / min, grinding depth 0.08 mm, ultrasonic vibration frequency 30 kHz, and ultrasonic amplitude 4 μm. The inner wall profile was ground by using the ultrasonic vibration grinding process.

[0059] The results show that the use of the SiC f grinding method for the inner wall profile of the SiC / SiC ceramic matrix composite flame tube realizes the high-efficiency and high-quality grinding of the inner and outer circular profiles of the SiC / SiC ceramic matrix composite flame tube. f The one-pass machining time of grinding is shortened from the original 120 min to the current 20 min, and the machining efficiency is increased by 500%.

[0060] In summary, the present invention provides a method for machining the SiC f / SiC ceramic matrix composite flame tube and its outer profile. By reasonably planning the grinding path and the structural parameters of the grinding tool, taking advantage of the ultrasonic vibration assisted grinding process, and selecting an appropriate ultrasonic amplitude, the grinding force, grinding heat and tool wear during the grinding process are reduced, the tool durability is improved. Compared with the traditional tool path, the machining efficiency is increased by 500%, and at the same time, the cost of the grinding tool 1 is reduced. The surface roughness and profile accuracy of the machined inner and outer wall profiles meet the design requirements. It realizes the high-efficiency and high-quality grinding of the inner or outer wall workpiece 2 of the SiC / SiC ceramic matrix composite flame tube, promotes the breakthrough of the precision machining technology of ceramic matrix composite components, and lays a certain technical foundation for promoting the engineering application of ceramic matrix composites. f The above is only the preferred embodiment of the present invention, and it is not used to limit the technical solution of the present invention. Those skilled in the art should understand that without departing from the spirit and principle of the present invention, the technical solution can be modified and replaced simply. These modifications and replacements also fall within the protection scope covered by the claims.

[0061] The above is only the preferred embodiment of the present invention, and it is not used to limit the technical solution of the present invention. Those skilled in the art should understand that without departing from the spirit and principle of the present invention, the technical solution can be modified and replaced simply. These modifications and replacements also fall within the protection scope covered by the claims.

Claims

1. A SiC f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: include: Obtaining the machining radius and profile requirements of the outer surface of the inner or outer wall workpiece (2) of the flame tube; According to the machining radius and profile requirements of the outer surface of the workpiece (2) on the inner or outer wall of the flame tube, the grinding machining rotation index angle is obtained; Determine the diameter of the grinding head of the grinding tool (1) according to the grinding rotation indexing angle; According to the diameter of the grinding head of the grinding tool (1), a suitable grinding tool (1) is selected to perform ultrasonic vibration-assisted grinding processing on the outer surface of the workpiece (2) inside or outside the flame tube.

2. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The axis of the grinding tool (1) is perpendicular to the axis of the workpiece (2) inside or outside the flame tube.

3. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: According to the machining radius and profile requirements of the outer surface of the flame tube inner or outer wall workpiece (2), the method for obtaining the grinding rotation indexing angle is as follows: cos(α / 2)=R / (R+H) (1 / 6)F≤H≤(1 / 4)F Wherein, α is the grinding rotation index angle; R is the machining radius of the outer profile surface of the workpiece (2) on the inner or outer wall of the flame tube; and F is the 1 / 2 profile value of the inner or outer wall of the workpiece (2) on the flame tube.

4. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The method for determining the diameter of the grinding head of the grinding tool (1) according to the grinding rotation indexing angle is: ΦC=2×(A+B) A=tan(α / 2)×R Wherein, ΦC is the diameter of the grinding head of the grinding tool (1); 3mm≤B≤6mm; α is the grinding rotation indexing angle; and R is the machining radius of the outer surface of the workpiece (2) on the inner or outer wall of the flame tube.

5. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The grinding head of the grinding tool (1) is a brazed diamond grinding head.

6. The SiC according to claim 5 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The particle size of the diamond abrasive grains on the brazed diamond grinding head is 150-250 meshes.

7. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The grinding rotation index angle can be divided by 360°.

8. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The grinding tool (1) comprises a clamping portion, wherein the diameter ΦD of the clamping portion satisfies: 6 mm ≤ ΦD ≤ M (mm), where M is the maximum clamping diameter of the ultrasonic vibration grinding tool holder.

9. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube outer surface processing method, characterized in that: The grinding speed of the ultrasonic vibration-assisted grinding process is 6000-11000 rpm / min, the feed speed is 1000-1500 mm / min, and the grinding depth is 0.05-0.1 mm; the frequency of the ultrasonic vibration is 28-38 kHz; and the amplitude of the grinding head of the grinding tool (1) is 4-8 um.

10. A SiC f / SiC ceramic matrix composite flame tube, characterized in that: The outer surface is processed by the outer surface processing method described in any one of claims 1 to 9.

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