A method for machining the inner hole of an elongated thin-walled ceramic matrix composite pipe

Abstract

The present application belongs to the technical field of thin-walled ceramic matrix composite pipe processing, and proposes an elongated thin-walled ceramic matrix composite pipe inner hole processing method, which overcomes the problems of easy deformation, cutting chatter and difficult control of processing size precision and straightness index in the prior art. First, the elongated thin-walled ceramic matrix composite pipe is positioned and clamped on the clamping execution system, then the flexible cutter is inserted into the inner hole of the elongated thin-walled ceramic matrix composite pipe, the cutter hose is adjusted to be the same height as the chuck of the clamping mechanism, then the abrasive pump is used to feed abrasive into the cutter, and when the abrasive fills the elongated thin-walled ceramic matrix composite pipe and overflows into the abrasive tank, the machine tool and the pipe retractor are started for grinding processing. The pipe prepared by the present application maintains the original precision of the profile, uniformly and controllably removes the material, and ensures the size precision of the small size change of the mold channel.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic matrix composite material processing, and particularly relates to a processing method for an inner hole of an elongated thin-wall ceramic matrix composite material pipe. BACKGROUND

[0002] The ceramic matrix composite material refers to a composite material formed by introducing a reinforcing material into a ceramic matrix, with the reinforcing material as a dispersed phase and the ceramic matrix as a continuous phase. The ceramic matrix composite material has excellent properties such as high strength, high hardness, high elastic modulus and thermal stability, and is widely used in the fields of aerospace, photovoltaic, nuclear industry and medical materials. The elongated pipe has a large length-diameter ratio and small rigidity, and it is difficult to ensure the uniformity of the wall thickness, coaxiality and straightness of the pipe after mechanical processing by using conventional mechanical processing methods, thereby affecting the use performance of the pipe.

[0003] The thin-wall ceramic matrix composite pipe has a large length-diameter ratio and belongs to a typical weak-rigidity part, and is prone to deformation and cutting chatter during processing. It is difficult to control the size precision and straightness index. The inner hole of the elongated pipe is a deep and long hole, and the processing space is limited. It is difficult to cool and lubricate and to chip and break the chips by using the traditional drilling method. Heat is easily accumulated, and the tool is severely worn. In addition, the high temperature causes thermal expansion deformation of the part, which affects the size precision.

[0004] Chinese patent CN201910336483.5 discloses a thin-wall elongated pipe integral precision processing method. The processing method for the inner hole is drilling and boring the inner hole, and then honing the inner hole. In the processing process, the size tolerances of the inner hole and the outer circle need to be controlled, and the wall thickness tolerance is indirectly ensured. The requirements for the tool are also high.

[0005] The patent differs from the traditional thin-wall elongated pipe processing device in that the inner hole of the elongated thin-wall ceramic matrix composite pipe is processed by using dynamic pressure effect. SUMMARY

[0006] The purpose of the present application is to provide a processing method for the inner hole of an elongated thin-wall ceramic matrix composite pipe, which overcomes the problem that the existing method cannot realize the processing method for the wall thickness uniformity of the large length-diameter ratio and thin-wall ceramic matrix composite material, and can produce a large length-diameter ratio and thin-wall pipe, and the inner hole roughness is ensured.

[0007] To achieve the above purpose, the technical scheme of the present application is as follows:

[0008] A processing method for the inner hole of an elongated thin-wall ceramic matrix composite pipe, which uses a processing device for the inner hole of an elongated thin-wall ceramic matrix composite pipe to process the inner hole of the elongated thin-wall ceramic matrix composite pipe, and specifically includes the following steps:

[0009] Step A, placing the workpiece: the elongated thin-walled ceramic matrix composite pipe is placed on the clamping execution system and one end is extended by a certain length, and the other end is increased by a center support;

[0010] Step B, connecting the flexible cutter: (a) the flexible cutter is filled with the one end of the filler and the other end is connected with the pipe collecting and releasing machine inside the elongated thin-walled ceramic matrix composite pipe; (b) the pipe collecting and releasing machine is lifted to be concentric with the three-jaw chuck of the clamping execution system, so as to ensure that the flexible cutter is straight in the horizontal direction, and the length L of the flexible cutter is greater than the length L0 of the elongated thin-walled ceramic matrix composite pipe;

[0011] Step C, grinding 1 is introduced: (a) the abrasive pump is connected with the abrasive box, the side of the flexible cutter which is not sealed by the filler is connected with the abrasive feeding thin tube connected with the abrasive pump, the abrasive boxes are placed at both ends of the elongated thin-walled ceramic matrix composite pipe to receive the overflowed abrasive 1, and the abrasive pump is connected with the power supply to pump the abrasive 1 in the abrasive box into the abrasive feeding thin tube; (b) the abrasive 1 is pumped into the hose through the bidirectional quick connector, and under the action of pressure, the abrasive flows into the elongated thin-walled ceramic matrix composite pipe from the small holes of the hose 4 and the waist-shaped holes of the sleeve 3;

[0012] Step D, grinding: when the abrasive is fully introduced and the abrasive flowing out from both ends of the elongated thin-walled ceramic matrix composite pipe is uniform, the machine tool is started, the elongated thin-walled ceramic matrix composite pipe rotates under the action of the three-jaw chuck, and after reaching a stable rotating speed, the pipe collecting and releasing machine is started to make the flexible cutter realize relative movement with the thin-walled ceramic matrix composite pipe.

[0013] The flexible cutter penetrates through the entire elongated thin-walled ceramic matrix composite pipe, the abrasive is introduced into the flexible cutter, and the flexible cutter moves horizontally at a certain speed to process the inner hole of the elongated thin-walled ceramic matrix composite pipe.

[0014] Compared with the prior art, the present application has the following advantages:

[0015] 1. The present application overcomes the shortcomings of the prior art that the inner hole of the material with large length-diameter ratio cannot be uniformly machined, especially the roughness, roundness and coaxiality of the inner hole of the thin-walled ceramic matrix composite material, and realizes the precision machining of the inner hole of the thin-walled ceramic matrix composite material by utilizing the dynamic pressure grinding effect, which realizes the precision machining of the inner hole of the thin-walled composite pipe that cannot be realized by traditional inner hole machining.

[0016] 2. The present application adopts the flexible cutter composed of the hose with small holes, the outer part of which is increased by a certain angle circular truncated cone micro-edge and the sleeve with waist-shaped holes, which ensures the coaxiality during inner hole machining and avoids the phenomenon of scratching the hole wall to form spiral line corrugation during traditional drilling and boring machining. The flexible cutter avoids the deflection phenomenon caused by the insufficient rigidity of the traditional machining cutter, and ensures the roundness of the inner hole of the machined thin-walled ceramic matrix composite pipe.

[0017] 3. This invention employs a fluid-guided abrasive processing method, ensuring effective cooling of the cutting area and continuous chip removal, guaranteeing continuous machining and extending the lifespan of the abrasive grains. Conventional cooling methods cannot directly inject cutting fluid into the cutting area during ultra-deep hole machining, resulting in inconsistent cooling and chip removal effects. This makes it unsuitable for machining thin-walled ceramic matrix composites. Due to the high hardness of thin-walled ceramic matrix composites, traditional finishing broaches easily generate cutting heat during cutting. High cutting zone temperatures, high friction coefficients, and poor thermal conductivity can easily lead to tool overheating and oxidation, accelerating tool wear. This flexible tool effectively avoids these phenomena.

[0018] 4. This invention employs dynamic pressure grinding with fluid abrasive to deburr, remove flash, and round the corners of the workpiece surface to be machined, thereby reducing the waviness and roughness of the workpiece surface and achieving precision machining. This effectively ensures the roughness requirements of the inner hole of the thin-walled ceramic matrix composite material, maintains the original accuracy of the contour, removes material uniformly and controllably, and ensures the dimensional accuracy of small changes in the mold channel. Attached Figure Description

[0019] Figure 1(a) is a schematic diagram of the principle of dynamic pressure grinding with abrasive material introduced;

[0020] Figure 1(b) is a side view of Figure 1(a).

[0021] Figure 2 This is a schematic diagram of a flexible cutting tool installed in a thin-walled ceramic matrix composite tube.

[0022] Figure 3 It is a process flow chart.

[0023] In the diagram: 1-Abrasive; 2-Frustum-shaped micro-blade; 3-Sleeve; 4-Hose. Detailed Implementation

[0024] The specific embodiments of the present invention are described in detail below with reference to the technical solutions and accompanying drawings.

[0025] like Figure 2 As shown, a processing device for the inner hole of a slender, thin-walled ceramic matrix composite tube includes a flexible cutting tool, a clamping and actuation system, a material feeding module, and a feeding motion system.

[0026] The flexible cutting tool is located inside a slender, thin-walled ceramic matrix composite tube, which includes a frustum-shaped micro-blade 2, a sleeve 3, and a flexible tube 4; the flexible tube 4 has several small holes for abrasive overflow; several equidistant frustum-shaped micro-blades 2 are glued to the flexible tube 4, and sleeves 3 with waist-shaped holes are installed between the frustum-shaped micro-blades 2, each sleeve 3 having a waist-shaped hole; both ends of the flexible tube 4 are sealed with filler.

[0027] The clamping execution system comprises a bearing, gear I, gear II, hollow short shaft and short shaft chassis; gear I is located on the machine tool spindle, gear II is connected with the hollow short shaft, gear I and gear II constitute parallel gear transmission, and the power of the machine tool spindle is transmitted to the hollow short shaft; the hollow short shaft is connected with the short shaft chassis through the bearing; one end of the hollow short shaft is provided with a shoulder hole and is connected with the three-jaw chuck;

[0028] The elongated thin-walled ceramic matrix composite pipe is arranged in the hollow short shaft, one end of the elongated thin-walled ceramic matrix composite pipe is clamped by the three-jaw chuck, and the other end of the elongated thin-walled ceramic matrix composite pipe extends out of the hollow short shaft;

[0029] The feeding motion system is located on both sides of the whole clamping execution system, and the feeding motion system comprises a pipe feeding and releasing machine and a pipe feeding and releasing machine hose; the pipe feeding and releasing machine is located on both sides of the machine tool, one end of the pipe feeding and releasing machine passes through the pipe feeding and releasing machine hose, and the other end of the pipe feeding and releasing machine is directly connected to the other end of the hose 4, and the other end of the hose 4 is used for linear relative motion of the flexible cutter and the thin-walled ceramic matrix composite pipe;

[0030] The material feeding module is located around the machine tool, and the material feeding module comprises a material feeding pipe, a two-way quick connector, an abrasive pump and an abrasive box; the abrasive pump is located on one side of the machine tool, one end of the abrasive pump is connected to the abrasive box, and the other end of the abrasive pump is connected to the material feeding pipe; the material feeding pipe and the pipe feeding and releasing machine hose are respectively connected to the other end of the hose 4 through the two-way quick connector; the abrasive box is provided with two and is located at two ends of the elongated thin-walled ceramic matrix composite pipe, and is used for receiving overflowed abrasive during machining and supplying abrasive; after the abrasive pump is pumped into the elongated thin-walled ceramic matrix composite pipe to make the abrasive uniformly flow out, the machine tool is started to reach a stable rotating speed, the pipe feeding and releasing machine is located at both ends of the machine tool and has the same height as the three-jaw chuck, the pipe feeding and releasing machine is rotated to repeatedly feed and release the flexible cutter to pull, and the grinding of the inner hole of the thin-walled ceramic matrix composite pipe is completed.

[0031] The sum of the hose 4 and the maximum diameter of the circular truncated cone micro blade 2 is less than the inner diameter of the elongated thin-walled ceramic matrix composite pipe. The circular truncated cone micro blades 2 are spaced apart.

[0032] As shown in Figure 3 Fig. 1, the processing device for the inner hole of the elongated thin-walled ceramic matrix composite pipe is used to process the inner hole of the elongated thin-walled ceramic matrix composite pipe, and specifically comprises the following steps:

[0033] Step 11, placing a workpiece: the elongated thin-walled ceramic matrix composite pipe is placed on the clamping execution system and one end of the elongated thin-walled ceramic matrix composite pipe extends out by a certain length, and the other end of the elongated thin-walled ceramic matrix composite pipe is supported by a center support;

[0034] Step 12, connecting a flexible cutter: (a) one end of the flexible cutter sealed by the filler is arranged to pass through the elongated thin-walled ceramic matrix composite pipe and is connected to the pipe feeding and releasing machine; (b) the pipe feeding and releasing machine is lifted to be concentric with the three-jaw chuck of the clamping execution system, the horizontal direction of the flexible cutter is ensured to be straight, and the length L of the flexible cutter is ensured to be greater than the length L0 of the elongated thin-walled ceramic matrix composite pipe;

[0035] Step 13, the abrasive (1) is fed in: (a) the abrasive pump is connected with the abrasive tank, the side of the flexible cutter not sealed by the filler is connected with the feeding tube connected with the abrasive pump, the abrasive tank is placed at both ends of the elongated thin-walled ceramic matrix composite pipe to receive the overflowed abrasive 1, the abrasive pump is connected with the power supply to pump the abrasive 1 in the abrasive tank into the feeding tube; (b) the abrasive 1 is pumped into the hose through the bidirectional quick connector, and the abrasive flows into the elongated thin-walled ceramic matrix composite pipe from the small holes of the hose 4 and the waist-shaped holes of the sleeve 3 under the action of the pressure;

[0036] Step 14, grinding is performed to process the inner hole of the elongated thin-walled ceramic matrix composite pipe and grind the inner hole: when the abrasive is fully fed in and the abrasive flowing out from both ends of the elongated thin-walled ceramic matrix composite pipe is uniform, the machine tool is started, the elongated thin-walled ceramic matrix composite pipe rotates under the action of the three-jaw chuck, and after the stable rotating speed is reached, the pipe collecting and releasing machine is started to enable the relative movement of the flexible cutter relative to the thin-walled ceramic matrix composite pipe.

Claims

1. A method for machining the inner hole of a slender, thin-walled ceramic matrix composite tube, characterized in that, The inner hole of a slender, thin-walled ceramic matrix composite tube is machined using a machining device, specifically including the following steps: Step A, placing the workpiece: The slender thin-walled ceramic matrix composite tube is placed on the clamping execution system with one end extending a certain length and the other end supported by a central frame; the flexible tool is located inside the slender thin-walled ceramic matrix composite tube, which includes a frustum-shaped micro-blade (2), a sleeve (3) and a flexible tube (4); the flexible tube (4) is provided with several small holes for the abrasive (1) to overflow; several equidistant frustum-shaped micro-blades (2) are glued onto the flexible tube (4), and sleeves (3) with waist-shaped holes are installed between the frustum-shaped micro-blades (2), and each sleeve (3) has a waist-shaped hole; both ends of the flexible tube (4) are sealed with filler; Step B, Connecting the flexible cutter: (a) The end of the flexible cutter sealed by the filler passes through the inside of the slender thin-walled ceramic matrix composite tube and is connected to the tube take-up and unload machine; (b) Raise and lower the tube take-up and unload machine to be concentric with the three-jaw chuck of the clamping execution system to ensure that the flexible cutter is straight in the horizontal direction and that the length L of the flexible cutter is greater than the length L0 of the slender thin-walled ceramic matrix composite tube. Step C, Abrasive (1) is introduced: (a) The abrasive pump is connected to the abrasive box, and the side of the flexible tool that is not sealed with filler is connected to the feed tube connected to the abrasive pump. The abrasive boxes are placed at both ends of the slender thin-walled ceramic matrix composite tube to receive the overflowing abrasive (1). The abrasive pump is powered on to pump the abrasive (1) in the abrasive box into the feed tube: (b) The abrasive (1) is pumped into the hose (4) through the bidirectional quick connector. Under pressure, the abrasive (1) flows into the slender thin-walled ceramic matrix composite tube from the small hole of the hose (4) and the waist-shaped hole of the sleeve (3). Step D, Grinding: When the abrasive (1) is fully introduced and the abrasive (1) flowing out from both ends of the slender thin-walled ceramic matrix composite tube is uniform, start the machine tool. The slender thin-walled ceramic matrix composite tube rotates under the action of the three-jaw chuck. After reaching a stable speed, start the tube take-up and untake-down machine so that the flexible tool can achieve relative movement with respect to the thin-walled ceramic matrix composite tube.

2. The method for machining the inner hole of a slender, thin-walled ceramic matrix composite tube according to claim 1, characterized in that, The flexible tool penetrates the entire slender thin-walled ceramic matrix composite tube, and abrasive (1) is introduced into the flexible tool. The flexible tool moves horizontally at a certain speed to process the inner hole of the slender thin-walled ceramic matrix composite tube.

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