SiCf / SiC ceramic matrix composite flame tube side face hole machining method and flame tube

Abstract

The invention relates to the technical field of flame tube machining, in particular to a SiCf / SiC ceramic matrix composite flame tube side face hole machining method and a flame tube. According to the method, the diameter of a milling and grinding tool is determined by obtaining the diameter of a side hole to be machined, the overhanging amount of the tool is reduced, fluttering is restrained, and therefore the phenomena of edge breakage, fracture or layering are reduced; a feeding mode of combining planar spiral and axial layering with radial spiral is adopted in a matched mode, a side hole to be machined is milled and ground, machining microcracks and edge chipping can be further effectively restrained for high-brittleness SiCf / SiC materials by removing materials layer by layer and reducing cutting force, the method is simple, has multi-degree-of-freedom compatibility, can be suitable for machining holes at various angles, and is suitable for large-scale production. Rapid process derivation of holes is achieved, and the problems that side face hole machining tools are multiple in variety requirement, low in product machining precision and machining efficiency and high in cost are solved.

Description

Technical Field

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

[0002] SiC f / SiC ceramic matrix composite (Silicon Carbide Fiber Reinforced Silicon Carbide Matrix Composites) is a high-performance composite material with silicon carbide fibers as the reinforcement and silicon carbide ceramics as the matrix. It combines the high strength and high modulus of silicon carbide fibers and the high temperature resistance, oxidation resistance, and corrosion resistance of the ceramic matrix, and has the characteristics of low density, high temperature-bearing capacity, and high hardness, and has broad application prospects in the field of hot-end components of advanced aeroengines. However, the high hardness, brittleness, and non-uniformity of the SiC f / SiC ceramic matrix composite make it face problems such as large tool wear and even difficult machining, and poor machinability of the material in machining.

[0003] In the field of aeroengines, the inner and outer wall dimensions and shapes of the SiC f / SiC ceramic matrix composite combustion chamber flame tube that requires high temperature resistance should match the engine and be lightweight. It adopts an annular thin-wall structure, and multiple side holes with different diameters and at a certain angle to the axis are designed on the wall. Conventional drilling and milling methods are often used in existing machining to process side holes, which not only require frequent tool changes and are prone to tool wear, but also defects such as delamination, tearing, burrs, and chipping are extremely likely to occur in the hole opening area, resulting in low machining efficiency, low product yield, and large losses. Summary of the Invention

[0004] Aiming at the problems in the prior art such as the need for a large variety of side hole machining tools, low machining accuracy and efficiency of products, and high cost, the present invention provides a method for machining side holes of a SiC f / SiC ceramic matrix composite flame tube and the flame tube.

[0005] To achieve the above object, the present invention adopts the following technical solutions: The present invention provides a method for machining side holes of a SiC f / SiC ceramic matrix composite flame tube, including: Obtaining the diameter of the side hole to be machined and confirming the diameter of the milling cutter; Select a milling and grinding tool with a suitable structure according to the diameter of the milling and grinding tool, and adopt a feed method combining planar spiral and axial layer-by-layer with radial spiral to mill and grind the side hole to be machined to obtain a side hole; wherein, during the milling and grinding process, the axis of the milling and grinding tool is parallel to the designed axis of the side hole to be machined.

[0006] Optionally, the milling and grinding tool is a PCD fine-tooth micro-edge milling cutter.

[0007] Optionally, the milling and grinding tool includes a tool shank and a milling and grinding part connected to the tool shank; an avoidance groove is provided at the end of the milling and grinding part, and a transition arc is provided between the avoidance groove and the end face of the milling and grinding part.

[0008] Optionally, the avoidance groove is a circular avoidance groove with a depth of 0.5 - 1 mm.

[0009] Optionally, the method for obtaining the diameter of the side hole to be machined and confirming the diameter of the milling and grinding tool is as follows: B = ΦA / 2-(ΦD + ΦC) / 2 B - R ≥ 0.5 mm Wherein, R is the radius of the transition arc; ΦA is the diameter of the side hole to be machined; ΦD is the diameter of the milling and grinding tool; ΦC is the diameter of the avoidance groove.

[0010] Optionally, the method for milling and grinding the side hole to be machined by adopting the feed method combining planar spiral and axial layer-by-layer with radial spiral to obtain a side hole is as follows: Adopt the feed method of planar spiral and axial layer-by-layer to rough machine the side hole to be machined until the unilateral allowance of the hole reaches a certain threshold, and end the rough machining; After the rough machining is completed, adopt the feed method of radial spiral to machine the side hole to be machined to the required hole diameter to obtain a side hole.

[0011] Optionally, the pitch of the feed in the feed method of planar spiral and axial layer-by-layer is 0.20 - 0.30 mm; the pitch of the feed in the feed method of radial spiral is 0.05 - 0.10 mm.

[0012] Optionally, the machining parameters for milling and grinding are as follows: Rotational speed n: 10000 - 18000 rpm / min; Feed rate f: 100 - 300 mm / min; Cutting depth ap: 0.05 - 0.1 mm.

[0013] Optionally, during the milling and grinding process, polytetrafluoroethylene is used for auxiliary support at the outlet part of the side hole to be machined.

[0014] The present invention also provides a kind of SiC fThe SiC / SiC ceramic matrix composite flame tube is machined by using the above-mentioned side hole machining method.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for machining side holes of a SiC f / SiC ceramic matrix composite flame tube. This method determines the diameter of the milling cutter by obtaining the diameter of the side hole to be machined, and can dynamically match the cutter diameter according to the hole diameter to reduce the cutter overhang and suppress chatter, so as to reduce the phenomena of chipping, cracking or delamination; combined with the feed mode of combining planar spiral and axial layer-by-layer with radial spiral, the side hole to be machined is milled. By removing materials layer by layer, the cutting force is reduced. For high-brittle SiC f / SiC materials, machining microcracks and edge chipping can be further effectively suppressed. At the same time, the spiral feed path extends the contact period between the milling cutter and the material, promotes the uniform dissipation of cutting heat, and avoids material phase change or thermal stress cracking caused by excessive local temperature rise; this method is simple and only one kind of cutter is needed to complete the machining throughout the process. It not only has low requirements for the types of cutters, but also has multi-degree-of-freedom compatibility, and is suitable for machining holes at various angles. The feed path can be parametrically modeled to realize the rapid process derivation of holes. While ensuring the machining yield and product quality, the machining cycle is greatly shortened and the machining cost is reduced. Through the innovative kinematic planning and process parameter coupling design, this method has made significant technological breakthroughs in the field of high-efficiency precision machining of difficult-to-machine ceramic matrix composites, and is particularly suitable for the mass production scenario of hot-end components of aeroengines.

[0016] The milling cutter is a polycrystalline diamond close-tooth micro-edge milling cutter. PCD remains chemically inert at high temperatures and has extremely high wear resistance, effectively avoiding diffusion wear with SiC, achieving cross-grain micro-fracture rather than macroscopic cracking. The densely distributed micro-edges cut into the material through phase difference, reducing the amplitude of cutting force fluctuation by 60% - 70%, suppressing high-frequency chatter, and ensuring that Ra meets the design requirements.

[0017] The milling cutter includes a tool shank and a milling part connected to the tool shank; an avoidance groove is provided at the end of the milling part, and a transition arc is provided between the avoidance groove and the end face of the milling part. Through the design of the transition arc and avoidance groove of the milling cutter, a stepped chip space is formed for the milling cutter. By dynamically constraining the avoidance groove and the diameter of the milling cutter, while ensuring the effective machining of the cutting edge of the milling part, the interference risk caused by the radial deflection of the milling cutter is eliminated, forming a "progressive cutting envelope surface", further improving the machining accuracy and machining quality.

[0018] When milling and grinding, a feed method combining planar spiral and axial layer-by-layer is adopted for rough machining to achieve equal-volume material removal with a continuously varying radius, which can effectively avoid sudden fractures of brittle materials. The control of the layer thickness limits the maximum undeformed chip thickness below the SiC grain size, enabling the material to be removed in a micro-fracture form. After rough machining, a radial spiral feed method is adopted for finish machining. Through the geometric envelope effect of the side cutting edge of the tool, the remaining allowance is gradually reduced to within the tolerance band, while the cutting force gradually decreases, completely eliminating the risk of edge chipping, providing a standardized solution for hole machining of hot-end components of aeroengines under extreme working conditions.

[0019] The pitch of the feed in the planar spiral and axial layer-by-layer feed method is 0.20 - 0.30 mm; the pitch of the feed in the radial spiral feed method is 0.05 - 0.10 mm. The control of the rough machining pitch can ensure the stability of cutting. At the same time, a "chip breaking - chip evacuation" cycle is formed, and combined with centrifugal chip evacuation, the rough machining efficiency is improved; the control of the finish machining pitch realizes a high cutting edge overlap rate per revolution, ensuring machining accuracy.

[0020] The setting of the machining parameters for the milling and grinding can ensure the balance of heat input during machining and the control of cutting depth, extend the service life of the tool, and ensure the accuracy and quality of the milling and grinding.

[0021] During milling and grinding, polytetrafluoroethylene is used for auxiliary support at the outlet of the hole to be machined on the machining side. Polytetrafluoroethylene forms a flexible buffer on the outlet side of the hole to be machined on the machining side, and absorbs the sudden impact load at the moment when the milling and grinding tool penetrates through elastic deformation, thereby further suppressing chipping, cracking or delamination of the hole to be machined on the machining side; at the same time, polytetrafluoroethylene has good heat resistance and low thermal conductivity, which can effectively block the conduction of cutting heat to the non-machining area, and then prevent the propagation of microcracks induced by thermal stress, thus ensuring the product yield of machining.

[0022] A kind of SiC f / SiC ceramic matrix composite flame tube processed by using the above side hole machining method. This flame tube, due to containing the above SiC f / The innovation and breakthrough of the SiC ceramic matrix composite side hole machining process have the characteristics of good stability, low density and long service life, which will promote the technological upgrading in the civil and military aviation fields, lay a foundation for the low-cost manufacturing technology of aeroengines, and accelerate the industrialization process of aeroengines. Brief Description of the Drawings

[0023] Figure 1 It is a schematic flow chart of the side hole machining method for a kind of SiC f / SiC ceramic matrix composite flame tube of the present invention.

[0024] Figure 2 For the SiC of the present inventionf Top view and corresponding sectional view of the tool and hole states during the machining method of the side holes of the / SiC ceramic matrix composite flame tube, where a is the top view and b is the sectional view.

[0025] Figure 3 Tool path diagram of the feed mode for the milling and grinding process of the present invention, where a is the tool path diagram of the plane spiral and axial layer-by-layer feed mode, and b is the tool path diagram of the radial spiral feed mode.

[0026] Figure 4 Structural schematic diagram of a test piece of the outer wall of a certain flame tube in the specific embodiment of the present invention.

[0027] Figure 5 Structural schematic diagram of the milling and grinding tool selected in the specific embodiment of the present invention.

[0028] Figure 6 In the specific embodiment of the present invention, SiC f Top view and corresponding sectional view of the tool and hole states during the machining method of the side holes of the / SiC ceramic matrix composite flame tube, where a is the top view and b is the sectional view.

[0029] Among them, 1 - side hole to be machined, 2 - milling and grinding tool, 21 - tool shank, 22 - milling and grinding part, 23 - relief groove, 24 - transition arc. Specific embodiment

[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 in conjunction with the accompanying 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 description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes 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 that are not clearly listed or are inherent to these processes, methods, products or devices.

[0032] The present invention will be further described in detail below in conjunction with specific embodiments, which are explanations of the present invention rather than limitations.

[0033] See Figure 1 , the present invention provides a method for machining side holes of a SiC f / SiC ceramic matrix composite flame tube, including: S1: Obtain the diameter of the side hole 1 to be machined, and confirm the diameter of the milling and grinding tool 2. Preferably, see Figure 2 , the milling and grinding tool 2 is a PCD fine-tooth micro-edge milling cutter, including a tool holder 21 and a milling and grinding part 22 connected to the tool holder 21; an avoidance groove 23 is provided at the end of the milling and grinding part 22, and a transition arc 24 is provided between the avoidance groove 23 and the end face of the milling and grinding part 22; preferably, the avoidance groove 23 is a circular avoidance groove with a depth of 0.5-1 mm, and the shank diameter of the tool holder 21 ≤ Φ13 mm to be installed in an ultrasonic vibration-assisted grinding device. The specific method is: B = ΦA / 2 - (ΦD + ΦC) / 2 B - R ≥ 0.5 mm Wherein, R is the radius of the transition arc 24; ΦA is the diameter of the side hole 1 to be machined; ΦD is the diameter of the milling and grinding tool 2; ΦC is the diameter of the avoidance groove 23.

[0034] S2: Select a milling and grinding tool 2 with a suitable structure according to the diameter of the milling and grinding tool 2, and adopt a feed method combining planar spiral and axial layer-by-layer with radial spiral to mill the side hole 1 to be machined to obtain a side hole; wherein, during milling, the axis of the milling and grinding tool 2 is parallel to the designed axis of the side hole 1 to be machined. The specific method is: See Figure 3 a, Adopt a feed method of planar spiral and axial layer-by-layer to rough machine the side hole 1 to be machined until the unilateral allowance of the hole reaches a certain threshold, and end the rough machining; preferably, the pitch of the feed of the planar spiral and axial layer-by-layer feed method is 0.20-0.30 mm; when the unilateral allowance of the hole reaches 0.20-0.30 mm, end the rough machining; See Figure 3 b, After the rough machining is completed, adopt a radial spiral feed method to machine the side hole 1 to be machined to the required hole diameter to obtain a side hole. Preferably, the pitch of the feed of the radial spiral feed method is 0.05-0.10 mm; The machining parameters of the milling are: Rotational speed n: 10000-18000 rpm / min; Feed rate f: 100-300 mm / min; Cutting depth ap: 0.05-0.1 mm; During the milling and grinding process, water-based cutting fluid is used for cooling. During operation, select a suitable milling and grinding tool according to the above method and correctly install it on the tool holder of the ultrasonic grinding device. Turn on the power of the ultrasonic vibration-assisted grinding device. The frequency selection range of the ultrasonic vibration is 38 - 41 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 2 - 6 μm. Operate the machining center, set parameters, and call the program verified by simulation to complete the milling and grinding of the side holes. After completing the milling and grinding of the side holes, turn off the power of the ultrasonic vibration-assisted grinding system. Preferably, considering the hard and brittle characteristics of the SiC f / SiC composite material in the fixture design, it is necessary to use polytetrafluoroethylene for auxiliary support at the outlet part of the processed hole to further avoid chipping, cracking or delamination during the hole processing, so as to achieve efficient and high-quality machining of the side holes of the outer ring of the ceramic matrix composite material flame tube.

[0035] This method determines the diameter of the milling and grinding tool 2 by obtaining the diameter of the side hole 1 to be processed. The tool diameter can be dynamically matched according to the hole diameter to reduce the tool overhang and suppress chatter, so as to reduce the phenomena of chipping, cracking or delamination. Combined with the tool path of combining planar spiral and axial layer-by-layer with radial spiral, the side hole 1 to be processed is milled and ground. By removing materials layer by layer, the cutting force is reduced. For the highly brittle SiC f / SiC material, it can further effectively suppress machining microcracks and edge chipping. At the same time, the spiral tool path extends the contact period between the milling and grinding tool 2 and the material, promotes the uniform dissipation of cutting heat, and avoids material phase change or thermal stress cracking caused by excessive local temperature rise. This method is simple and has multi-degree-of-freedom compatibility, suitable for hole machining at various angles. The tool path can be parametrically modeled to achieve rapid process derivation of holes. While ensuring the processing yield and product quality, it greatly shortens the processing cycle and reduces the processing cost.

[0036] A SiC f / SiC ceramic matrix composite material flame tube is processed by using the above side hole processing method. Because this flame tube contains the above SiC f / The innovation and breakthrough of the SiC ceramic matrix composite material side hole processing technology have the characteristics of good stability, low density and long service life. It will promote the technological upgrading in the civil and military aviation fields, lay a foundation for the low-cost manufacturing technology of aeroengines, and accelerate the industrialization process of aeroengines.

[0037] Example 1 See Figure 4, taking a test piece of the outer wall of a combustion chamber as an example, the technical solution of the present invention will be further described. The diameters of the side holes 1 to be machined on the test piece of the outer wall of the combustion chamber include diameters of Φ6.5 and Φ15.8 mm. The axis of the side hole 1 to be machined has a certain angle with the axis of the outer ring of the combustion chamber. The machining requirements are that the surface roughness Ra of the evenly distributed holes is ≤3.2 um, the positional tolerance relative to the datum is ≤0.3 mm, and there are no defects such as delamination, tearing, burrs, and chipping in the hole mouth area; analyze the machining characteristics and machining requirements of the side holes of the SiC f / SiC ceramic matrix composite outer ring test piece of the combustion chamber, and select the KMC800S-UMT turning and milling composite machining center as the milling and grinding equipment.

[0038] See Figure 5 and Figure 6 , select the milling and grinding tool 2 as a PCD fine-tooth micro-edge milling cutter, including a tool shank 21 made of tungsten steel; the milling and grinding part 22 is made of PCD. The PCD fine-tooth edge length on the milling and grinding part 22 is 2.5 mm, and the number of edges is 22; the diameter of the relief groove 23 is Φ1.2 mm, and the radius of the transition arc 24 is 0.1 mm. According to the formula: B = ΦA / 2-(ΦD + ΦC) / 2 B - R ≥ 0.5 mm Actually calculate that ΦD satisfies less than or equal to 4.5 mm and less than or equal to 11.2. The milling and grinding tool 2 that meets the use requirements on site is a milling and grinding tool 2 with a diameter of Φ4 mm, which can meet the requirements of machining two kinds of side holes at the same time; in addition, considering the strength problem of the milling and grinding tool 2, generally the diameter of the milling and grinding tool 2 is not less than 3 mm, and the minimum diameter of the milling and grinding tool 2 can be set according to the machining strength requirements; Design the tool path. First, use the plane spiral and axial layer-by-layer method for rough machining. The Φ6.5 mm hole is machined to Φ6.2 mm, and the Φ15.8 mm is machined to Φ15.5 mm. Then, use the radial spiral method for finish machining to the required hole diameter. During the machining process, the axis of the milling and grinding tool 2 is parallel to the axis of the side hole 1 to be machined on the outer ring of the combustion chamber.

[0039] Combined with the ultrasonic vibration-assisted milling and grinding process test of SiCf / SiC ceramic matrix composite, determine the milling and grinding machining parameters, and conduct geometric simulation on the milling and grinding process.

[0040] Milling and grinding machining parameters: Rotational speed n: 11000 rpm / min; Feed rate f: 200 mm / min; Cutting depth ap: 0.08 mm; Plane spiral radial feed: 0.20 mm; Axial spiral feed: 0.10 mm; 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 SiC f / SiC ceramic matrix composite outer ring workpiece on the special tooling. The tooling is designed to use polytetrafluoroethylene for auxiliary support at the outlet of the machined hole to prevent the workpiece from chipping, cracking or delaminating during hole machining. After positioning and clamping, adjust and place the workpiece at the machining position.

[0041] Select the cooling method: During the milling and grinding of the side hole 1 on the to-be-machined side of the SiC f / SiC ceramic matrix composite outer ring, use water-based cutting fluid for cooling.

[0042] Perform the milling and grinding of the side hole 1 on the to-be-machined side of the SiC f / SiC ceramic matrix composite outer ring.

[0043] Correctly install the selected integral PCD fine-tooth micro-edge milling cutter on the tool holder of the ultrasonic grinding device.

[0044] Turn on the power of the ultrasonic vibration-assisted grinding device, and select a frequency of 38 kHz for the ultrasonic vibration. Test the vibration state of the ultrasonic vibration device and detect the vibration amplitude of the grinding head, and control the vibration amplitude within 3 μm.

[0045] Operate the machining center, set parameters, call the program, and complete the milling and grinding of the side hole.

[0046] After completing the milling and grinding of the side hole, turn off the power of the ultrasonic vibration-assisted grinding system.

[0047] In this embodiment, analyze the structural characteristics and machining requirements of the side hole 1 on the to-be-machined side of the SiC f / SiC ceramic matrix composite flame tube outer ring, select the KMC800S-UMT turning and milling compound machining center, reasonably select the milling and grinding tool, and reasonably plan the tool path. Adopt the process parameters: spindle speed 11000 r / min, feed speed 200 mm / min, cutting depth 0.08 mm, plane spiral radial feed 0.20 mm, axial spiral feed 0.10 mm, ultrasonic vibration frequency 38 kHz, ultrasonic amplitude 3 μm, and complete the milling and grinding of the outer wall side hole by using the ultrasonic vibration grinding process. The results show that the milling and grinding method for the side hole 1 on the to-be-machined side of the SiC f / SiC ceramic matrix composite flame tube outer ring realizes the high-efficiency machining of the side hole milling and grinding of the SiC f / SiC ceramic matrix composite flame tube outer ring.

[0048] In summary, the present invention provides a method for machining side holes of a SiCf / SiC ceramic matrix composite flame tube and a flame tube. By leveraging the advantages of ultrasonic vibration-assisted grinding process and selecting an appropriate ultrasonic amplitude, the cutting force, cutting heat, and tool wear during the grinding process are reduced, and the tool durability is improved. In cooperation with the use of an integral PCD fine-tooth micro-edge milling cutter and the planning of a reasonable tool path, the machined side hole 1 is processed with appropriate parameters, without chipping, cracking, or delamination on the surface, and both the roughness and the profile accuracy of the surface meet the design requirements, realizing the high-efficiency and high-quality grinding machining of the side holes 1 of the inner and outer ring test pieces of the SiC f / SiC ceramic matrix composite flame tube, promoting the breakthrough of precision machining technology for ceramic matrix composite components and laying a certain technical foundation for the engineering application of ceramic matrix composites. This side hole machining method is not only applicable to the machining of the inner and outer ring side holes of the SiC f / SiC ceramic matrix composite flame tube, but also applicable to the machining of holes in other materials with high hardness and high brittleness, providing technical support and inspiration for the industrialization of hole machining for brittle materials.

[0049] The above are only the preferred embodiments of the present invention and are not used to limit the technical solutions of the present invention. Those skilled in the art should understand that without departing from the spirit and principles of the present invention, the technical solutions can be subject to several simple modifications and substitutions, and these modifications and substitutions also fall within the protection scope covered by the claims.

Claims

1. A SiC f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, include: Obtain the diameter of the side hole (1) to be processed, and confirm the diameter of the milling tool (2); A milling tool (2) of suitable structure is selected according to the diameter of the milling tool (2), and a planar spiral and axial layered combined with radial spiral cutting method is used to perform milling processing on the side hole (1) to be processed, thereby obtaining the side hole; wherein, during the milling processing, the axis of the milling tool (2) is parallel to the designed axis of the side hole (1) to be processed.

2. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The milling tool (2) is a PCD close-tooth micro-edge milling cutter.

3. The SiC according to claim 2 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The milling tool (2) comprises a tool handle (21) and a milling portion (22) connected to the tool handle (21); an avoidance groove (23) is provided at the end of the milling portion (22), and a transition arc (24) is provided between the avoidance groove (23) and the end surface of the milling portion (22).

4. SiC according to claim 3 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The avoidance groove (23) is a circular avoidance groove with a depth of 0.5 to 1 mm.

5. The SiC according to claim 4 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The method for obtaining the diameter of the side hole (1) to be processed and confirming the diameter of the milling tool (2) is as follows: B=ΦA / 2-(ΦD+ΦC) / 2 BR≥0.5mm Wherein, R is the radius of the transition arc (24); ΦA is the diameter of the side hole (1) to be processed; ΦD is the diameter of the milling tool (2); and ΦC is the diameter of the avoidance groove (23).

6. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The method of using a planar spiral and axial layered combined with a radial spiral cutting method to mill and grind the side hole (1) to be processed is as follows: The side hole (1) to be processed is rough-machined by adopting a planar spiral and axial layered cutting method until the single-side allowance of the hole reaches a certain threshold, and then the rough machining is terminated; After the rough machining is completed, the side hole (1) to be machined is machined to the required hole diameter using a radial spiral cutting method to obtain a side hole.

7. The SiC according to claim 6 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The pitch of the planar spiral and axial layered feeding method is 0.20-0.30 mm; the pitch of the radial spiral feeding method is 0.05-0.10 mm.

8. The SiC according to claim 1 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, The processing parameters for milling and grinding are: Speed ​​n: 10000~18000rpm / min; Feed speed f: 100~300mm / min; Cutting depth ap: 0.05~0.1mm.

9. The SiC according to any one of claims 1 to 8 f / SiC ceramic matrix composite flame tube side hole processing method, characterized in that, During milling and grinding, polytetrafluoroethylene is used for auxiliary support at the exit of the side hole to be processed.

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

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