Method for machining inter-blade flow channel of diameter-expanding casing

Abstract

The invention discloses an inter-blade flow channel machining method of a radial expansion casing. The inter-blade flow channel machining method comprises the following steps that S1, an inter-blade flow channel to be machined is divided into an area A, an area B and an area C on the basis of the maximum discharge sectional area and the shortest motion trail principle; s2, based on the areas A, B and C, electrodes a, b and c are designed and manufactured according to the set offset, an electrode d is designed and manufactured according to the outline of the blade basin in the area A, and an electrode e is designed and manufactured according to the outline of the blade back and the outline of the blade basin in the areas B and C; s3, a mechanical cutting technology is adopted for preliminarily removing the blade-to-blade flow channel allowance so as to form N preliminarily-machined flow channels; s4, an electrode a, an electrode b and an electrode c are sequentially adopted to stretch into the preliminary machining flow channel to remove the blade-to-blade flow channel allowance, and a rough machining flow channel is formed; s5, an electrode d and an electrode e are sequentially adopted to stretch into the rough machining flow channel to remove the reserved inter-blade flow channel set allowance so as to form the inter-blade flow channel; compared with the prior art, the electrode length is short, the moving track is short, the manufacturing difficulty is low, and the machining efficiency and the machining precision of the inter-blade flow channel are high.

Description

Technical Field

[0001] This invention relates to the field of radial expansion casing processing technology, and in particular, to a method for processing the inter-blade flow channel of a radial expansion casing. Background Technology

[0002] Difficult-to-machine materials such as titanium alloys or high-temperature alloys are widely used in the manufacture of radial expansion casings for aero engines due to their high specific strength, high heat resistance, and low density. The radial expansion casing is one of the core components of an aero engine, its function being to convert the kinetic energy of accelerated high-speed airflow into pressure energy. The main structure of the radial expansion casing consists of radially diffused, upper and lower closed channels (referred to as inter-blade channels) composed of upper channels, lower channels, and blades. The blank of the radial expansion casing is a forged integral titanium alloy blank. Due to the difficulty in machining the material, the high dimensional accuracy, and the deep and narrow space, existing mechanical cutting methods cannot completely remove the excess material from the inter-blade channels on the blank. Therefore, existing inter-blade channel machining methods combine electrical discharge machining (EDM) with abrasive flow machining.

[0003] For example, Chinese invention patent application CN117464108A discloses a machining process for the flow channel of a radial expansion casing and an abrasive flow fixture. The machining process for the flow channel of the radial expansion casing includes the following steps: S100, slotting is machined on the radial expansion casing to form a blank channel; S200, a first roughing electrode is used to remove the excess material of the blank channel to form a primary machining flow channel; S300, a second roughing electrode is designed according to the design contour of the flow channel, and the designed second roughing electrode is inserted into the primary machining flow channel and moved two-dimensionally along the flow channel by a robot to form a rough machining flow channel; S400, an electrode is used to electrolytically machine the semi-finished flow channel to form a flow channel that meets the design size requirements; S500, the radial expansion casing is clamped using an abrasive flow fixture, and the abrasive flow is guided to machine the roughness of the flow channel to Ra0.8.

[0004] However, due to the high dimensional accuracy of the inter-blade flow channel, the large variation in the area of ​​the inlet / outlet, and the fact that the material is titanium alloy, the length of the processing electrode used in the above scheme is greater than the length of the inter-blade flow channel, and the width of the processing electrode is smaller than the width of the throat. This results in a small discharge area of ​​the electrode used for processing, leading to high electrode wear and low material removal efficiency when processing to remove the excess material from the inter-blade flow channel.

[0005] Furthermore, due to the characteristics of electrical discharge machining (EDM), the accuracy of the electrode directly affects the accuracy of the machined contour. In the above method, the electrode length is required to be greater than the length of the entire inter-blade flow channel, and the electrode contour accuracy is higher than the blade contour accuracy. The electrode movement trajectory needs to be linked with the Z-axis using the vertical rotary table of the machine tool, and the movement direction can only be from the outlet (largest cross-sectional area) of the inter-blade flow channel to the inlet. With a long electrode movement trajectory, the manufacturing difficulty of the electrode is high, and the manufacturing accuracy is difficult to guarantee. When removing the excess material from the inter-blade flow channel, it is difficult to guarantee the contour requirements of the blade leading edge and blade body, resulting in a low blade contour machining pass rate.

[0006] In addition, to ensure a smooth connection between the leading edge R of the blade and the blade base and back, multiple cutting operations are required. In the above scheme, this position is the farthest point of electrode processing, and electrode wear is difficult to control. This can easily cause deformation of the leading edge of the blade and produce cutting marks. Cutting marks will cause stress concentration at the leading edge R of the blade, and in severe cases, it may even become unusable and scrapped.

[0007] Furthermore, since the longer the inter-blade flow channel of the radial expansion casing, the greater the change in cross-sectional area and the stronger the conversion capability, the above scheme requires that the length of the roughing and finishing electrode must be greater than the length of the flow channel in order to complete the removal of the inter-blade flow channel residue and meet the accuracy requirements. In order to ensure that the residue residue in the inter-blade flow channel is smoothly discharged along the machining direction, the radial expansion casing needs to be installed vertically on the horizontal worktable of the EDM machine tool, which results in a high requirement for the machine tool Z-axis travel distance and a high difficulty in manufacturing large-size electrodes.

[0008] Furthermore, in the aforementioned processing method, graphite electrodes are first used to machine the inter-blade flow channel to a satisfactory level, ensuring a surface roughness of R1.6. Then, an abrasive flow fixture is designed, and special abrasives are used to repeatedly grind the flow channel until the surface roughness of the inter-blade flow channel reaches the design requirement of Ra0.8. This method involves a complex process combining electrical discharge machining (EDM) and abrasive flow machining, making dimensional control difficult. Graphite is chosen as the electrode material primarily because of its high high-temperature strength, low coefficient of thermal expansion, and good electrical and thermal conductivity. However, graphite has relatively weak impact and bending resistance, and the average particle diameter of the graphite material directly affects the surface quality of the part. Smaller average particle size results in more uniform discharge, more stable discharge, better surface quality, and less electrode wear. Larger average particle size leads to better material removal rates in roughing, but results in poorer surface finish and greater electrode wear. These characteristics also lead to the following problems when machining inter-blade flow channels: 1) The electrode contour designed according to the shape of the inter-blade flow channel is complex and has poor structural rigidity. Graphite materials are generally machined using a five-axis CNC milling machine. If the electrode itself has insufficient structural rigidity or the cutting tool is worn, it is easy to generate vibration and graphite is easy to break, making it difficult to guarantee the electrode size and surface quality requirements; 2) Due to the concentrated discharge effect at sharp corners and the high resistivity of 10-25µΩ.m, graphite electrodes hinder the uniform diffusion of current, resulting in a high edge loss rate. In fact, they are not suitable for machining deep, long, complex, and precision inter-blade flow channels. Summary of the Invention

[0009] The purpose of this invention is to provide a method for machining the inter-blade flow channel of a radial expansion casing, addressing at least one of the technical problems mentioned in the background art.

[0010] According to one aspect of the present invention, a method for machining inter-blade flow channels of a radial expansion casing is provided, for machining N inter-blade flow channels along the circumferential direction on a radial expansion casing blank, where N is an integer greater than 1, comprising the following steps: S1: Dividing the inter-blade flow channels to be machined into regions A, B, and C based on the principle of maximum discharge cross-sectional area and shortest motion trajectory, wherein region A is the region between the leading edge of the blade and the leading edge of the adjacent blade, region B is the region with the smallest equal cross-sectional area in the direction of the blade back, and region C is the region between the radial outer edge of region B and the air outlet; S2: Based on regions A, B, and C, designing and manufacturing electrodes a, b, and c according to a set offset, designing and manufacturing electrode d according to the blade basin contour in region A, and designing and manufacturing electrode e according to the blade back and blade basin contours in regions B and C, wherein electrode a is used for removing the remaining material in region A during rough machining, electrode b is used for removing the remaining material in region B during rough machining, electrode c is used for removing the remaining material in region C during rough machining, electrode d is used for removing the remaining material in region A during finish machining, and electrode e is used for finish machining. S3: Remove excess material from areas B and C during the machining process; S4: Use mechanical cutting to initially remove excess material from the inter-blade flow channels to form N preliminary machining channels; S5: Sequentially insert electrodes a, b, and c into one of the preliminary machining channels to remove excess material from the inter-blade flow channels to form a rough machining channel. Repeat the above steps to sequentially remove excess material from the inter-blade flow channels in the other preliminary machining channels in the circumferential direction to form N rough machining channels. A set allowance is reserved in each of the N rough machining channels. The movement trajectories of electrodes a and b... S5: Electrodes d and e are inserted into one of the roughing channels in sequence to remove the reserved inter-blade flow channel setting allowance to form an inter-blade flow channel. The above steps are repeated to remove the reserved inter-blade flow channel setting allowance in other roughing channels in the circumferential direction in sequence to form N inter-blade flow channels in the circumferential direction. Among them, the movement trajectory of electrode d is from the blade leading edge to the air outlet, and the movement trajectory of electrode e is from the air outlet to the blade leading edge.

[0011] As a further improvement to the above technical solution: Further, step S4 specifically includes the following steps: S41: Electrode a is inserted from the leading edge of the blade into the preliminary processing channel to remove the excess material in the inter-blade channel within region A, with a predetermined allowance. Simultaneously, a liquid spraying device is installed at the inlet of the movement trajectory of electrode a, and a liquid suction device is installed at the outlet of the movement trajectory of electrode a; S42: Electrode b is inserted from the leading edge of the blade into the preliminary processing channel to remove the excess material in the inter-blade channel within region B, with a predetermined allowance. Simultaneously, a liquid spraying device is installed at the inlet of the movement trajectory of electrode b. S43: An suction device is installed at the exit of the movement trajectory of electrode b; S44: Electrode c is inserted from the air inlet into the preliminary processing channel to remove the excess material in the inter-blade channel of region C and reserve a set allowance. At the same time, a spray device is installed at the inlet of the movement trajectory of electrode c and an suction device is installed at the exit of the movement trajectory of electrode c; S45: Repeat steps S41-S43 to remove the excess material in the inter-blade channel of other preliminary processing channels in the circumferential direction in turn to form N rough processing channels. A set allowance is reserved in each of the N rough processing channels.

[0012] Furthermore, the pressure of the spraying device is 0.5 MPa-1 MPa.

[0013] Furthermore, the pressure of the liquid aspiration device is 0.5 MPa-1 MPa.

[0014] Furthermore, electrodes a, b, and c are graphite electrodes, and electrodes d and e are tungsten-copper electrodes.

[0015] Further, step S5 specifically includes the following steps: S51: Using electrode d, extend from the leading edge of the blade into the roughing flow channel to remove the reserved inter-blade flow channel setting allowance in region A; S52: Using electrode e, extend from the outlet into the roughing flow channel to sequentially remove the reserved inter-blade flow channel setting allowance in regions c and b, thereby forming an inter-blade flow channel; S53: Repeat steps S51-S52 to sequentially remove the reserved inter-blade flow channel setting allowance in other roughing flow channels in the circumferential direction, so as to form N inter-blade flow channels in the circumferential direction.

[0016] Furthermore, a processing machine tool is arranged on the worktable. The processing machine tool includes an X-axis and a Y-axis that are perpendicular to each other in the horizontal plane. In step S51, the X-axis is moved first, and then the Y-axis is moved to the processing position so that the electrode d is moved to the processing position, thereby removing the reserved allowance for the inter-blade flow channel in region A.

[0017] Furthermore, between steps S2 and S3, there is also the following step: the radial expansion casing blank is mounted horizontally on the worktable along the radial direction, and each electrode is mounted using a 3R reference sheet. During the processing of each electrode, the mounting plane of each electrode is made parallel to the trajectory movement plane of the electrode.

[0018] Furthermore, the offset is set to 0.6mm-1mm.

[0019] Furthermore, the allowance is set to 0.3mm-0.6mm.

[0020] The present invention has the following beneficial effects: The inter-blade flow channel machining method of the present invention divides the inter-blade flow channel to be machined into regions A, B, and C based on the principles of maximum discharge cross-sectional area and shortest motion trajectory. Then, based on regions A, B, and C, electrodes a, b, and c are designed and manufactured according to a set offset. Electrode d is designed and manufactured according to the blade basin contour within region A, and electrode e is designed and manufactured according to the blade back and blade basin contours within regions B and C. Electrodes a, b, and c are used for rough machining, while electrodes d and e are used for finish machining. During the machining process, the length of a single electrode is shortened by machining the corresponding regions with multiple electrodes. The required electrode length is short, reducing the manufacturing difficulty of the electrodes and improving the manufacturing accuracy of the electrodes. This, in turn, improves the machinability of the inter-blade flow channel contour. Furthermore, through reasonable region division and manufacturing electrodes within the divided regions, the maximum efficiency is achieved. The increased processing width of a single electrode leads to a larger discharge area, improving material removal rate and thus enhancing the efficiency of rough machining for removing excess material. During rough machining, electrodes a, b, and c move towards each other; during finish machining, electrodes d and e move towards each other. The short electrode movement trajectories further reduce the manufacturing difficulty and improve the manufacturing precision of the electrodes. Compared to existing technologies, this solution completes both rough and finish machining using multiple electrodes, with each electrode moving towards the other during machining. The short movement trajectories significantly shorten the required electrode length, reducing manufacturing difficulty and improving manufacturing precision. This, in turn, improves the machining precision of the inter-blade flow channel. Simultaneously, the increased processing width and discharge area of ​​the electrodes enhance the machining efficiency of the inter-blade flow channel, making it highly practical and suitable for widespread promotion and application.

[0021] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart illustrating the steps of a preferred embodiment of the inter-blade flow channel processing method for a radial expansion casing of the present invention. Figure 2 This is a schematic diagram of the rough machining of electrodes a, b, and c in the inter-blade flow channel machining method of the radial expansion casing according to a preferred embodiment of the present invention. Figure 3This is a schematic diagram of the structure of electrodes a, b, and c in the inter-blade flow channel processing method of the radial expansion casing according to a preferred embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of electrode d in the inter-blade flow channel processing method of the radial expansion casing according to a preferred embodiment of the present invention; Figure 5 This is a schematic diagram of the finishing of electrodes d and e in the inter-blade flow channel processing method of the radial expansion casing according to a preferred embodiment of the present invention. Detailed Implementation

[0023] The following description provides specific application scenarios and requirements for this specification, intended to enable those skilled in the art to make and use the contents of this specification. Various partial modifications to the disclosed embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but rather to the widest scope consistent with the claims.

[0024] The terminology used herein is for the purpose of describing particular exemplary embodiments only and is not restrictive. For example, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” as used herein may also include the plural forms. When used in this specification, the terms “comprising,” “including,” and / or “containing” mean that the associated integers, steps, operations, elements, and / or components are present, but do not preclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups, or that other features, integers, steps, operations, elements, components, and / or groups may be added to the system / method.

[0025] Considering the following description, these and other features of this specification, as well as the operation and function of the related components of the structure, and the economy of assembly and manufacture of the parts, can be significantly improved. All of these form part of this specification with reference to the accompanying drawings. However, it should be clearly understood that the drawings are for illustrative and descriptive purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not drawn to scale.

[0026] like Figures 1-5As shown, the method for machining inter-blade flow channels of the radial expansion casing in this embodiment is used to machine N inter-blade flow channels along the circumferential direction on the radial expansion casing blank, where N is an integer greater than 1. The method includes the following steps: S1: Based on the principle of maximum discharge cross-sectional area and shortest motion trajectory, the inter-blade flow channels to be machined are divided into regions A, B, and C. Region A is the region between the leading edge of the blade and the leading edge of adjacent blades; Region B is the region with the smallest equal cross-sectional area in the blade back direction; Region C is the region between the radial outer edge of Region B and the air outlet. S2: Based on regions A, B, and C, electrodes a, b, and c are designed and manufactured according to a set offset. Electrode d is designed and manufactured according to the blade basin contour in region A. Electrode e is designed and manufactured according to the blade back and blade basin contours in regions B and C. Electrode a is used for removing excess material in region A during rough machining; electrode b is used for removing excess material in region B during rough machining; electrode c is used for removing excess material in region C during rough machining; electrode d is used for removing excess material in region A during finish machining; and electrode e is used for removing excess material in region A during finish machining. S3: Remove excess material in areas B and C; S4: Use mechanical cutting to initially remove excess material from the inter-blade flow channels to form N preliminary machining channels; S5: Sequentially insert electrodes a, b, and c into one of the preliminary machining channels to remove excess material from the inter-blade flow channels to form a rough machining channel. Repeat the above steps to sequentially remove excess material from the inter-blade flow channels in the other preliminary machining channels in the circumferential direction to form N rough machining channels. Each of the N rough machining channels has a predetermined allowance. The movement trajectories of electrodes a and b are as follows: From the leading edge of the blade to the outlet, the trajectory of electrode c is from the outlet to the leading edge of the blade; S5: Electrodes d and e are inserted into one of the roughing channels in sequence to remove the reserved inter-blade flow channel setting allowance to form an inter-blade flow channel. The above steps are repeated to remove the reserved inter-blade flow channel setting allowance in other roughing channels in the circumferential direction in sequence to form N inter-blade flow channels in the circumferential direction. Among them, the trajectory of electrode d is from the leading edge of the blade to the outlet, and the trajectory of electrode e is from the outlet to the leading edge of the blade.

[0027] like Figures 1-5As shown, specifically, the inter-blade flow channel processing method of the radial expansion casing of the present invention divides the inter-blade flow channel to be processed into regions A, B, and C based on the principles of maximum discharge cross-sectional area and shortest motion trajectory. Then, based on regions A, B, and C, electrodes a, b, and c are designed and manufactured according to a set offset. Electrode d is designed and manufactured according to the blade basin contour within region A, and electrode e is designed and manufactured according to the blade back and blade basin contours within regions B and C. Electrodes a, b, and c are used for roughing, while electrodes d and e are used for finishing. During the processing, the length of a single electrode is shortened by processing the corresponding regions with multiple electrodes. The required electrode length is short, reducing the manufacturing difficulty of the electrodes and improving the electrode manufacturing accuracy. This, in turn, improves the processing capability of the inter-blade flow channel contour. Furthermore, through reasonable region division and manufacturing electrodes within the divided regions, the maximum efficiency is achieved. Increasing the processing width of a single electrode increases the discharge area of ​​that electrode, improving material removal rate and thus enhancing the efficiency of rough machining for removing excess material. During rough machining, electrodes a, b, and c move towards each other; during finish machining, electrodes d and e move towards each other. The short electrode movement trajectories further reduce the manufacturing difficulty and improve the manufacturing precision of the electrodes. Compared to existing technologies, this solution completes both rough and finish machining using multiple electrodes, with each electrode moving towards the other during machining. The short movement trajectories significantly shorten the required electrode length, reducing manufacturing difficulty and improving manufacturing precision, thereby enhancing the machining precision of the inter-blade flow channel. Simultaneously, the increased electrode processing width and discharge area improve the machining efficiency of the inter-blade flow channel, making it highly practical and suitable for widespread promotion and application.

[0028] like Figure 2 As shown, in this embodiment, step S4 specifically includes the following steps: S41: Electrode a is inserted from the leading edge of the blade into the preliminary processing channel to remove the excess material in the inter-blade channel within region A, and a predetermined allowance is reserved. Simultaneously, a liquid spraying device is installed at the inlet of the movement trajectory of electrode a, and a liquid suction device is installed at the outlet of the movement trajectory of electrode a; S42: Electrode b is inserted from the leading edge of the blade into the preliminary processing channel to remove the excess material in the inter-blade channel within region B, and a predetermined allowance is reserved. Simultaneously, a liquid spraying device is installed at the inlet of the movement trajectory of electrode b. S43: An electrode c is inserted from the air inlet into the preliminary processing channel to remove the excess material in the inter-blade channel of region C and reserve a set allowance. At the same time, a liquid spraying device is set at the inlet of the moving trajectory of electrode c, and a liquid suction device is set at the outlet of the moving trajectory of electrode c. S44: Repeat steps S41-S43 to remove the excess material in the inter-blade channel of other preliminary processing channels in the circumferential direction in turn to form N rough processing channels. A set allowance is reserved in each of the N rough processing channels.

[0029] Specifically, rough machining involves removing large amounts of residue. During the rough machining of electrodes a, b, and c, a liquid spraying device is installed at the inlet of the movement trajectory of each electrode, and a liquid suction device is installed at the outlet of the movement trajectory of each electrode a. The liquid spraying device and the liquid suction device are used to increase the discharge capacity of processing waste, so that the excess residue in the processing process can be smoothly discharged along the processing direction.

[0030] In this embodiment, the pressure of the spraying device is 0.5 MPa-1 MPa. Specifically, when the pressure of the spraying device is between 0.5 MPa and 1 MPa, it ensures strong waste discharge capacity and smooth discharge of residual residue while maintaining high EDM efficiency for each electrode. When the pressure of the spraying device is less than 0.5 MPa, the waste discharge capacity is weak, and residual residue cannot be discharged smoothly. When the pressure of the spraying device is greater than 1 MPa, the waste discharge speed is too fast, and the EDM efficiency for each electrode is low.

[0031] In this embodiment, the pressure of the liquid suction device is 0.5 MPa-1 MPa. Specifically, when the pressure of the liquid suction device is between 0.5 MPa and 1 MPa, it ensures strong waste discharge capacity, easy formation of discharge channels, and smooth discharge of residual residue, while also achieving high EDM efficiency for each electrode. When the pressure of the liquid suction device is less than 0.5 MPa, the waste discharge capacity is weak, and residual residue cannot be discharged smoothly. When the pressure of the liquid suction device is greater than 1 MPa, the waste discharge speed is too fast, the discharge channel is not easy to form, unstable partial discharge is easily generated, and the EDM efficiency of each electrode is low.

[0032] It should be understood that electrical discharge machining (EDM) is performed in a liquid insulating working medium, and the smooth removal of electro-erosion products is one of the important factors affecting the stability of the discharge process. Currently, most cavity workpieces use low-pressure flushing fluid (pressure below 0.3 MPa) in EDM. This invention proposes to implement flushing and suction along the electrode feed trajectory. Experiments have shown that adjusting the flushing and suction pressure values ​​within the range of 0.5 MPa to 1 MPa can control the discharge state near the critical range of stable machining, without exhibiting abnormal machining states such as white smoke and large bubbles on the liquid surface, short circuits, or electric arcs. The stability of the discharge state is determined by the machine tool's computer CPU processor acquiring and processing abnormal pulse signals such as short circuits and electric arcs, and evaluating the stability of the EDM discharge gap state.

[0033] In this embodiment, electrodes a, b, and c are graphite electrodes, and electrodes d and e are tungsten-copper electrodes. Specifically, by using graphite electrodes a, b, and c, which are made of graphite material, the material removal rate and roughing efficiency are improved during the roughing process. By using tungsten-copper electrodes d and e, which are made of tungsten-copper alloy material, the high melting point and resistivity of the tungsten-copper alloy material help reduce electrode wear and improve discharge stability during the finishing process, thereby improving machining accuracy. Furthermore, the tungsten-copper alloy material has high bending strength and a certain degree of ductility, which helps reduce the manufacturing difficulty of electrodes d and e. In addition, the surface roughness of the tungsten-copper electrode material can reach within Ra0.2. Therefore, the inter-blade flow channel formed directly by machining electrodes d and e can meet the design requirement of surface roughness Ra0.8, eliminating the need for abrasive flow machining and avoiding the quality instability caused by abrasive flow machining. This also reduces the number of machining steps and improves machining efficiency. In terms of work efficiency, during rough machining, the excess material in regions B and C is removed by electrodes b and c respectively. Compared to finishing, this shortens the required electrode length, reduces manufacturing difficulty, and ensures manufacturing accuracy. During finishing, the excess material in regions B and C is removed solely by electrode e. While this electrode is longer than finishing, it is made of tungsten-copper, making it easier and more accurate to manufacture, thus ensuring machining precision. Furthermore, reducing the number of finishing electrodes also reduces the number of electrode tool contact points, which in turn helps control the contour dimensions of the tool contact point at the blade's leading edge. In this invention, the blade's leading edge R and the junction with the blade base are directly formed by electrode d. Therefore, it is only necessary to control the dimensions of the junction between the blade's leading edge R and the blade back, i.e., only the machining parameters of electrode e need to be controlled to ensure the relevant dimensions of the blade's leading edge R, avoiding tool marks and improving machining quality. like Figure 5 As shown, in this embodiment, step S5 specifically includes the following steps: S51: Electrode d is inserted from the leading edge of the blade into the roughing channel to remove the reserved inter-blade flow channel setting allowance in region A; S52: Electrode e is inserted from the outlet into the roughing channel to sequentially remove the reserved inter-blade flow channel setting allowance in regions c and b, thereby forming the inter-blade flow channel; S53: Steps S51-S52 are repeated to sequentially remove the reserved inter-blade flow channel setting allowance in other roughing channels in the circumferential direction, so as to form N inter-blade flow channels in the circumferential direction. Specifically, in the finishing process, the inter-blade flow channel is formed by electrodes d and e in sequence, and the movement trajectories are opposite. The electrode length is short, the movement trajectory is short, the electrode manufacturing is difficult, and the manufacturing precision is high, thus ensuring the contour size and surface roughness of the inter-blade flow channel.

[0034] like Figure 5As shown, in this embodiment, a machining tool is arranged on the worktable. The machining tool includes an X-axis and a Y-axis that are perpendicular to each other in the horizontal plane. In step S51, the X-axis is moved first, and then the Y-axis is moved to the machining position so that the electrode d is moved to the machining position, thereby removing the reserved allowance for the inter-blade flow channel in region A. Specifically, the above steps are used to maximize the discharge area of ​​the electrode d and improve the machining efficiency.

[0035] In this embodiment, between steps S2 and S3, the following step is also included: horizontally mounting the radial expansion housing blank on the worktable along the radial direction, then mounting each electrode using a 3R reference plate, and ensuring that the mounting plane of each electrode is parallel to the trajectory movement plane of the electrode during machining. Specifically, machining the radial expansion housing with the electrodes in the horizontal direction avoids the influence of the gravity of the parts and fixtures on the clamping process caused by vertically placed parts, reduces the difficulty of part clamping, and has no special requirements on the Z-axis travel range of the machine tool. At the same time, it shortens the total length of the electrodes, improves the electrode rigidity, and reduces the manufacturing difficulty. In addition, during finishing, the total movement trajectory of the electrodes is shorter, making it easier to control the dimensional accuracy requirements.

[0036] In this embodiment, the offset is set to 0.6mm-1mm. Specifically, when the offset is set between 0.6mm and 1mm, the low current loss of the graphite electrode can be effectively utilized, resulting in high material removal efficiency and no need for shaking during processing, thus achieving high processing efficiency. When the offset is set less than 0.6mm, in order to ensure sufficient trimming allowance during finishing, the electrode translation amount and pulse discharge energy are limited, which cannot effectively utilize the low current loss of the graphite electrode, resulting in low material removal efficiency. When the offset is set greater than 1mm, the electrode needs to be shaken during processing, and the translation amount during processing is large, resulting in low processing efficiency.

[0037] It should be understood that, based on the characteristics of electrical discharge machining (EDM), the electrode scaling must take into account factors such as pulse power, current density the electrode can withstand, discharge environment, and workpiece surface roughness requirements. The discharge requirements for rough machining are to allow for a suitable and uniform allowance for subsequent finishing, minimizing the allowance while ensuring final machining accuracy. The maximum pulse discharge energy for each electrical specification in rough machining must meet the requirements of electrode scaling and electrode discharge surface current density.

[0038] In this embodiment, the allowance is set to 0.3mm-0.6mm. Specifically, when the allowance is set between 0.3mm and 0.6mm, the material removal efficiency of roughing and finishing is high, the electrode wear of finishing is small, and the surface roughness accuracy after processing is high. When the allowance is less than 0.3mm, the titanium alloy discharge process is prone to abnormal phenomena such as secondary discharge and carbon deposition. Considering the long flow channel of the part, there is an alignment error in the transition between roughing and finishing electrodes. Setting the allowance below this is too small, and there is a risk that the surface may not be fully processed during finishing. When the allowance is greater than 0.6mm, in order to ensure the surface roughness and dimensional accuracy requirements, finishing is achieved by reducing the pulse discharge energy and reducing the size of the etching pit to ensure surface roughness and processing accuracy. Setting too much allowance above 0.6mm will lead to long finishing time, low efficiency, and quality risks such as cracks.

[0039] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0040] In summary, after reading the detailed disclosure of this specification, those skilled in the art will understand that the foregoing detailed disclosure is presented by way of example only and is not restrictive. Although not explicitly stated herein, those skilled in the art will understand that this specification requires various reasonable changes, improvements, and modifications to the embodiments. These changes, improvements, and modifications are intended to be made by this specification and are within the spirit and scope of the exemplary embodiments described herein.

[0041] Furthermore, certain terms in this specification have been used to describe embodiments of this specification. For example, "an embodiment," "an embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with that embodiment may be included in at least one embodiment of this specification. Therefore, it is to be emphasized and understood that two or more references to "an embodiment" or "an embodiment" or "alternative embodiment" in various parts of this specification do not necessarily refer to the same embodiment. Moreover, specific features, structures, or characteristics may be suitably combined in one or more embodiments of this specification.

[0042] It should be understood that in the foregoing description of the embodiments in this specification, various features are combined in a single embodiment, drawing, or description for the purpose of simplifying the description and aiding in the understanding of a feature. However, this does not mean that the combination of these features is necessary, and those skilled in the art may readily identify some of the devices as separate embodiments when reading this specification. That is, the embodiments in this specification can also be understood as an integration of multiple secondary embodiments. It is also valid when each secondary embodiment contains fewer than all the features of a single foregoing disclosed embodiment.

[0043] Each patent, patent application, publication of the patent application, and other materials such as articles, books, specifications, publications, documents, articles, etc., cited herein may be incorporated by reference. The entire contents used for all purposes, except for any history of prosecution documents associated with it, that may be inconsistent with or conflict with this document, or that may have a limiting effect on the widest extent of the claims, are now or hereafter associated with this document. For example, in the event of any inconsistency or conflict between the description, definition, and / or use of terms associated with any of the included materials and the terms, description, definition, and / or used in connection with this document, the terms used herein shall prevail.

[0044] Finally, it should be understood that the embodiments disclosed herein are illustrative of the principles of the embodiments described in this specification. Other modified embodiments are also within the scope of this specification. Therefore, the embodiments disclosed in this specification are merely examples and not limitations. Those skilled in the art can implement the applications described in this specification using alternative configurations based on the embodiments in this specification. Therefore, the embodiments in this specification are not limited to the embodiments precisely described in the applications.

Claims

1. A method for machining inter-blade flow channels in a radial expansion casing, used to machine N inter-blade flow channels along the circumferential direction on a radial expansion casing blank, where N is an integer greater than 1, characterized in that, Includes the following steps: S1: Based on the principle of maximum discharge cross-sectional area and shortest motion trajectory, the inter-blade flow channel to be processed is divided into regions A, B and C. Region A is the region between the leading edge of the blade and the leading edge of the adjacent blade, region B is the region with the smallest cross-sectional area in the direction of the blade back, and region C is the region between the radial outer edge of region B and the air outlet. S2: Based on regions A, B, and C, design and manufacture electrodes a, b, and c according to a set offset; design and manufacture electrode d according to the blade basin outline in region A; and design and manufacture electrode e according to the blade back and blade basin outlines in regions B and C. Electrode a is used for removing excess material in region A during rough machining; electrode b is used for removing excess material in region B during rough machining; electrode c is used for removing excess material in region C during rough machining; electrode d is used for removing excess material in region A during finish machining; and electrode e is used for removing excess material in regions B and C during finish machining. S3: Use mechanical cutting process to initially remove the excess material in the inter-blade flow channel to form N preliminary machined flow channels; S4: Electrodes a, b, and c are sequentially inserted into one of the preliminary machining channels to remove the inter-blade flow channel excess to form a rough machining channel. The above steps are repeated to remove the inter-blade flow channel excess in the other preliminary machining channels in the circumferential direction to form N rough machining channels. Each of the N rough machining channels has a set allowance. The movement trajectory of electrodes a and b is from the leading edge of the blade to the outlet, and the movement trajectory of electrode c is from the outlet to the leading edge of the blade. S5: Electrodes d and e are inserted into one of the roughing channels in sequence to remove the reserved inter-blade flow channel setting allowance to form an inter-blade flow channel. The above steps are repeated to remove the reserved inter-blade flow channel setting allowance in other roughing channels in the circumferential direction in sequence to form N inter-blade flow channels in the circumferential direction. The movement trajectory of electrode d is from the leading edge of the blade to the outlet, and the movement trajectory of electrode e is from the outlet to the leading edge of the blade.

2. The method for machining the inter-blade flow channel of the radial expansion casing according to claim 1, characterized in that, Step S4 specifically includes the following steps: S41: Electrode a is inserted from the leading edge of the blade into the preliminary processing channel to remove the excess material in the inter-blade channel of region A and reserve a set amount. At the same time, a liquid spraying device is set at the inlet of the moving trajectory of electrode a, and a liquid suction device is set at the outlet of the moving trajectory of electrode a. S42: Electrode b is inserted from the leading edge of the blade into the preliminary processing channel to remove the excess material in the inter-blade channel of region B and reserve a set amount. At the same time, a liquid spraying device is set at the inlet of the moving trajectory of electrode b and a liquid suction device is set at the outlet of the moving trajectory of electrode b. S43: Electrode c is inserted from the air inlet into the preliminary processing channel to remove the excess material in the inter-blade channel of region C and reserve a set amount. At the same time, a liquid spraying device is set at the inlet of the moving trajectory of electrode c, and a liquid suction device is set at the outlet of the moving trajectory of electrode c. S44: Repeat steps S41-S43 to remove the excess material in the inter-blade flow channels of other preliminary machining channels in the circumferential direction in turn to form N rough machining channels. Each of the N rough machining channels has a set allowance.

3. The method for machining the inter-blade flow channel of the radial expansion casing according to claim 2, characterized in that, The pressure of the spraying device is 0.5 MPa-1 MPa.

4. The method for machining the inter-blade flow channel of the radial expansion casing according to claim 2, characterized in that, The pressure of the liquid suction device is 0.5 MPa-1 MPa.

5. The method for machining the inter-blade flow channel of the radial expansion casing according to claim 1, characterized in that, Electrodes a, b, and c are graphite electrodes, and electrodes d and e are tungsten-copper electrodes.

6. The method for machining the inter-blade flow channel of the radial expansion casing according to any one of claims 1-5, characterized in that, Step S5 specifically includes the following steps: S51: Electrode d is inserted from the leading edge of the blade into the roughing flow channel to remove the reserved inter-blade flow channel setting allowance in area A; S52: Electrode e is inserted from the outlet into the roughing flow channel to remove the reserved inter-blade flow channel setting allowance in regions c and b in sequence, thereby forming the inter-blade flow channel; S53: Repeat steps S51-S52 to remove the reserved allowance for the inter-blade flow channel in other rough-machined flow channels in the circumferential direction in turn, so as to form N inter-blade flow channels in the circumferential direction.

7. The method for machining the inter-blade flow channel of the radial expansion casing according to any one of claims 1-5, characterized in that, The worktable is equipped with a machining tool, which includes an X-axis and a Y-axis that are perpendicular to each other in the horizontal plane. In step S51, the X-axis is moved first, and then the Y-axis is moved to the machining position so that the electrode d is moved to the machining position, thereby removing the reserved allowance for the inter-blade flow channel in area A.

8. The method for machining the inter-blade flow channel of the radial expansion casing according to any one of claims 1-5, characterized in that, The steps between step S2 and step S3 include: The radial expansion casing blank is mounted horizontally on the worktable, and then each electrode is mounted using a 3R reference plate. During the machining of each electrode, the mounting plane of each electrode is made parallel to the trajectory movement plane of the electrode.

9. The method for machining the inter-blade flow channel of the radial expansion casing according to any one of claims 1-5, characterized in that, Set the offset to 0.6mm-1mm.

10. The method for machining the inter-blade flow channel of the radial expansion casing according to any one of claims 1-5, characterized in that, The allowance is set to 0.3mm-0.6mm.

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