WO2023005011A1

WO2023005011A1 - Electrolytic machining method using dynamic deformation of flexible electrode, and application thereof

Info

Publication number: WO2023005011A1
Application number: PCT/CN2021/126103
Authority: WO
Inventors: 朱荻; 徐正扬; 刘琳
Original assignee: 南京航空航天大学
Priority date: 2021-07-28
Filing date: 2021-10-25
Publication date: 2023-02-02
Also published as: CN113478031B; CN113478031A; JP7390087B2; JP2023538702A

Abstract

An electrolytic machining method using dynamic deformation of a flexible electrode. Tubular or rod-like metal is used as a tool electrode (2) for electrolytic machining; the tool electrode (2) has a certain rigidity, but can be bent and deformed when a corresponding load is applied; when a complex profile is machined, a side wall of the tool electrode (2) serves as a machining surface to perform scanning-type electrolytic machining along a surface of the complex profile of a workpiece (3); and during a machining process, different loads are applied according to the curvature change characteristics of the profile of the workpiece, such that the tool electrode is dynamically deformed while being fed, and a deformed shape is similar to a mathematical model of a profile line of the workpiece, such that the machined profile of the workpiece approximates an ideal profile. By means of the electrolytic machining method using dynamic deformation of a flexible electrode, a complex profile can be machined by means of a simple-shaped electrode, thereby improving the electrolytic machining efficiency, and ensuring the machining precision. Further provided is an application of the electrolytic machining method using dynamic deformation of a flexible electrode.

Description

Dynamic Deformation Electrolytic Machining Method and Application of Flexible Electrode

technical field

The invention relates to a dynamic deformation electrolytic machining method and application of a flexible electrode, belonging to the technical field of electrolytic machining.

Background technique

Integral blisk parts are made of blades and hubs as a whole, replacing the usual connection structure of blade teeth and hub mortises plus locking plates, thereby reducing the number of parts, reducing the weight of the aero-engine, and improving the working efficiency of the engine. As the core component of an aero-engine, the manufacturing quality of the blisk directly affects the performance of the entire aero-engine. The blisk can be divided into an open blisk and a closed blisk according to whether there is a shroud structure on the top of the blade. The blisk of the closed blisk adds a whole circle of shroud structure to the top of the blade, which can effectively suppress the flutter of the blade; reduce The flow loss of the working fluid; improve the overall strength and stiffness of the blisk, so the application of the closed blisk in the aerospace field is increasing.

However, due to its complex structure, twisted airfoil, and the use of difficult-to-machine materials such as high-temperature alloys, it has brought great difficulties to processing and manufacturing. At present, the manufacturing process of closed blisks mainly includes traditional machining, precision casting, electric discharge machining and electrolytic machining.

In the patent "High-precision Closed Blisk Forming Method" (application number 201210588218.4, the applicant is the 60th Research Institute of the General Staff of the Chinese People's Liberation Army, the inventor is Wu Gaoqiang, Shi Xiaohong, Ding Lei, Zhuang Zhenyu and Cui Wei), the closed overall blisk is split into The cover plate, blade and chassis are processed by water jet cutting, turning, grinding and other processing techniques, and are welded as a whole by vacuum brazing. The method has the advantages of high machining precision and easy control of the machining process.

In the patent "A method for controlling the flow channel size of closed impeller investment precision castings" (application number 201911206733.X applicant Xi'an Aerospace Engine Co., Ltd., inventor Yang Huanqing, Wang Lin, Gao Huaisheng, Ji Yanqing, Wu Xiaoming and Chen Pengrong), the proposed flow channel size The control method solves the problem of poor dimensional accuracy of the flow channel of the closed impeller investment casting precision casting, improves the hydraulic performance index of the product, saves the trial production period of the product, and reduces the manufacturing cost.

In the patent "A Small-Gap Closed Aluminum Alloy Impeller Laser Selective Melting Forming Method" (application number 201910550775.9 applicant Xi'an Aerospace Engine Co., Ltd., inventor Li Hulin Yang Huanqing Wang Yun Wang Lin Leiyao), the process pre-compensation and addition are used to facilitate removal The columnar support ensures the dimensional accuracy, shape accuracy and surface roughness of the inner flow channel, making it possible to manufacture the overall additive manufacturing of small-gap closed aluminum alloy impellers.

In the patent "closed impeller and its forming method" (application number 201811546242.5 applicant Soochow University, inventor Shi Tuo, Chen Lei, Shi Shihong, Lu Jian, Fu Geyan), the laser cladding forming technology of internal optical powder feeding is adopted, and the blades are stacked and bridged by oblique orientation Forming can effectively avoid the problem of positional interference, and make the blade accumulation and bridge appearance good.

In the patent "A closed impeller EDM device and processing method" (application number 201611208198.8 applicant Beijing Institute of Electrical Processing, inventor Li Yanfu Jinjuan Yang Liguang Guo Yan Yufan), proposed multiple pre-processed electrodes Arranged in a circle, the number of pre-processed electrodes is the same as the number of flow channels of the closed impeller to be processed; and each pre-processed electrode corresponds to a flow channel inlet of the closed impeller to be processed during processing, solving the problem of closed-type impellers in the prior art. Each flow channel of the impeller is processed separately, and the processing efficiency is low.

Electrolytic machining is a process method based on the principle of anodic dissolution and by means of a shaped cathode to process the workpiece into a certain shape and size. Due to its advantages of not being affected by the mechanical properties of materials, no macro stress, no tool loss, and high material removal rate, electrolytic machining is widely used in aerospace, automobiles, weapons and other fields, especially in the overall blisk of aeroengines. In the processing and manufacturing of parts, electrolytic machining has become one of the main processing technologies for the processing and manufacturing of blisk parts.

At present, the electrolytic machining process of the overall blisk mainly includes two steps, the rough machining of the cascade channel and the fine machining of the blade profile. Many scholars and researchers have done a lot of research on the electrolytic machining of the blisk cascade channel and the electrolytic machining of the blisk blade profile. The electrolytic machining methods of the integral blisk cascade channel mainly include nesting electrolytic machining, radial feed electrolytic machining and numerical control electrolytic machining. The electrolytic machining method of the blade profile of the integral blisk mainly processes and shapes the blade profile through the opposite feeding of two forming cathodes.

In the patent "electrode for electrolytic grooving of blisks and processing method for electrolytic grooving of blisks" (application number 201410513097.6 applicant Shenyang Liming Aero Engine (Group) Co., Ltd., inventor Wang Dexin Zhu Hainan Yu Bingsheng Wenjuan) , through the nesting electrolytic machining method, the uniformity of the allowance after the slotting process is improved.

In the patent "A Whole Blisk Electrolytic Grooving Processing Ring Electrode and Process Method" (application number 201210367002.5 applicant Shenyang Liming Aero Engine (Group) Co., Ltd., inventor Zhu Hainan Yang Jianshi Yu Bing Li Wei), Through the nesting electrolytic machining method, the efficient machining of the wide-chord and large-twisted blade-shaped channel slotting of the overall blisk is realized.

In the patent "cathode system and processing method for electrolytic processing of insulating shielding casing materials" (application number 201710202429.2 applicant Nanjing University of Aeronautics and Astronautics, inventor Zhu Dong Hu Xingyan Zhu Di), a cathode system and processing method for electrolytic processing of insulating shielding casing materials are provided , effectively reduce the secondary corrosion of stray current on the surface of the workpiece, and improve the surface quality of the processed surface.

In the article "Cathode Design and Experiment of Radial Electrolytic Machining of Integral Blisk Based on Machinability Analysis of Cascade Channel" (authors Sun Lunye, Xu Zhengyang, Zhu Di, China Mechanical Engineering, 2013 Issue 09), the radial electrolytic machining method was proposed, At the same time, it takes into account the shape of the blade pot, blade back and wheel hub to achieve high-precision and high-efficiency machining.

In the patent "Tool and method for electrolytic processing of integral blisks capable of linear and rotary compound feed" (application number 201410013249.6 applicant Nanjing University of Aeronautics and Astronautics, inventor Xu Zhengyang Zhang Juchen Liu Jia Zhu Dong Zhu Di), it is proposed that the formed cathode is fed radially The composite rotary motion during the machining process can improve the applicability of the process, process the cascade channel with complex surface distortion, and improve the machining accuracy and level of the cascade channel.

In the patent "Electrolytic Machining Method of Integral Blisk with Rotary Feeding in Space" (Application No. 201410457130.8, applicant Nanjing University of Aeronautics and Astronautics, inventor Zhu Dongguzhou, Liu Jiafang, Zhongdong Xu Zhengyang and Zhu Di), it is proposed to use tool space rotary feeding composite The electrolytic machining of the cascade channel of the overall blisk is completed by tilting and swinging the workpiece, which significantly reduces the machining margin difference of the cascade channel and improves the machining accuracy of the cascade channel of the overall blisk.

In the patent "A non-uniform double-rotation variable machining blade cathode integral blisk electrolytic machining method" (application number 201910756930.2 applicant Nanjing University of Aeronautics and Astronautics, inventor Xu Zhengyang Wang Jing Zhu Di), the design of the cathode machining blade is a variable width machining blade , drive it to rotate radially in one direction according to the simulated trajectory; drive the blank to rotate according to the parameters optimized by simulation in conjunction with the cathode in variable direction and variable speed, forming a cascade channel on the blank to improve the uniformity of the machining allowance distribution.

In the patent "a cathode of a variable inner cavity tool for electrolytic processing of large twisted blade integral blisks" (application number 201910326896.5 applicant Anhui University of Science and Technology, inventor Sun Lunye Chen Hao Wanghui), proposed the electrolytic processing of large twisted blade integral blade The variable tool cathode of the inner cavity of the disc is used for processing the whole blisk blade with large twist and variable cross-section.

In the patent "A Method for Electrolytic Machining of Integral Blisks" (Application No. 201811128151.X applicant China Academy of Aviation Manufacturing Technology, inventor Huang Mingtao Zhang Mingqi Cheng Xiaoyuan Fu Junying), it is proposed to use tool cathode radial feed to process the blade cascade channel , to drive the blisk to rotate clockwise and counterclockwise, close to the cathode of the tool for electrolytic finishing.

In the article "Large-diameter integral impeller step-by-step electrolytic machining process and experiment" (author Wang Fuyuan, Xu Jiawen, Zhao Jianshe, Journal of Aeronautical Sciences, No. 12, 2010), the step-by-step numerical control electrolytic machining is proposed, and the blade processing is divided into processing blade basin, There are three processes of blade back and blade root, and electrolytic processing is carried out.

In the patent "Multi-electrode screw-feed integral impeller interblade flow path electrolytic machining method" (application number 200910025834.7 applicant Nanjing University of Aeronautics and Astronautics, inventor Zhu Di Xu Qing Xu Zhengyang), through the multi-dimensional interpolation movement between the tool cathode and the workpiece anode , using a simple shape of tubular electrodes to process the cascade channel.

In the patent "Electrolytic Machining Device and Method for Integral Blisk Surface Based on Three-dimensional Composite Flow Field" (application number 201310453440.8 applicant Nanjing University of Aeronautics and Astronautics, inventor Liu Jiawan Longkai Xu Zhengyang Zhu Dong), the proposed three-dimensional composite flow field It effectively increases the pressure of the fluid in the sudden change area of the flow channel and improves the accessibility of the flow field. At the same time, the electrolytic processing device ensures the stability of the flow field of the electrolyte, prevents the leakage of the electrolyte, isolates external interference, and realizes the overall blisk Stable processing of profiles.

Blisks are divided into open blisks and closed blisks, which can be subdivided into axial flow, guide type, centrifugal blisks and other types, which puts forward more requirements for electrolytic processing methods and equipment high demands. For the overall blisk with complex blade profile distortion, the design of the electrolytic machining cathode is also relatively complicated. If the cathode design can be simplified and the complex profile can be processed through a simple-shaped cathode while ensuring the machining accuracy, it will undoubtedly be greatly improved. Improve the electrolytic machining efficiency of the overall blisk, shorten the preparation period, and reduce the processing cost. Therefore, the present invention proposes a dynamic deformation electrolytic machining method for flexible electrodes.

Contents of the invention

Purpose of the invention:

The purpose of the present invention is to simplify the design of the cathode, process complex profiles such as closed integral blisks through electrodes with simple shapes, improve the efficiency of electrolytic machining, ensure the machining accuracy, and provide a dynamic deformation electrolytic machining method and application of flexible electrodes.

Technical solutions:

A dynamic deformation electrolytic machining method for a flexible electrode, characterized in that it includes the following process:

A tubular or rod-shaped metal with good corrosion resistance and certain rigidity, which can be bent and deformed when the corresponding load is applied, and recovers when the load is removed, is used as the tool electrode for electrolytic machining. When processing a complex profile such as a closed blisk, the side wall of the tool electrode is used as a processing surface to perform sweeping electrolytic machining along the surface of the complex profile of the workpiece. During the processing, according to the curvature change characteristics of the workpiece surface, by applying different loads, the tool electrode is dynamically deformed while feeding, and its deformed shape is similar to the mathematical model of the workpiece surface line, so that the machining The resulting workpiece profile is close to the ideal profile.

The dynamic deformation of the above-mentioned flexible electrode is characterized in that it includes the following process:

Step 1. According to the sampling data of the standard surface of the processed workpiece, the relationship between the deformation curvature of the flexible electrode and the curvature of the workpiece surface is established. The mathematical model establishment process is as follows:

Step 1-1. Sampling the surface of the workpiece to be processed, and applying the cosθ method to study its electrolytic machining forming law (Figure 1 is a schematic diagram of the electrolytic machining forming law), and simplify and approximate the complex electric field in the actual machining gap , mainly based on the following assumptions:

(1) The potential gradient along the direction of the current line remains unchanged, that is, the electric field intensity on the same current line is the same;

(2) Starting from the equipotential surface of the anode to the equipotential surface of the cathode, the potential gradually decreases, and the equipotential surface is orthogonal to the current line;

(3) The conductivity κ of the electrolyte in the processing gap is evenly distributed;

Step 1-2. After simplifying the approximate processing, according to the basic principles of electrolytic machining such as Ohm's law and Faraday's law, the equations related to the forming law are obtained:

U _R =U-δE

v _a = ηωi

In the formula: U _R is the voltage drop in the gap electrolyte; U is the voltage between the cathode and the anode; δE is the sum of the cathode and anode potential values; i is the current density; κ is the conductivity of the electrolyte; Δ is the processing gap ; v _a is the workpiece electrolysis speed; η is the current efficiency; ω is the volume electrochemical equivalent;

Step 1-3. When the electrolytic machining reaches the equilibrium state, the electric field parameter no longer changes with time, but is only a function of the spatial position, that is, the gap electric field is a steady electric field; according to Ohm's law and Faraday's law, establish the relevant workpiece electrolysis speed v _a The basic equation: v _a = v cosθ, simultaneous equations, deduce the calculation formula of the machining gap Δ:

In the formula: v is the feed speed of the cathode; θ is the angle between the normal direction of the workpiece surface and the feed direction of the cathode; Δ _b is the balance machining gap;

Steps 1-4. In the present invention, the tool cathode is a slender tubular or rod-shaped electrode for sweeping electrolytic machining, so the tool cathode can be simplified into a two-dimensional curve, and the sweeping process of the curve is the processed workpiece profile . Figure 2 is a schematic diagram of establishing the tool cathode coordinate system. During the dynamic deformation process of the flexible electrode, the coordinate relationship between each point of the flexible electrode (cathode) and the corresponding sample point of the workpiece surface is:

x=x _a -Δcosα

y=y _a -Δcosβ

In the formula: x and y are the coordinates of a certain point on the cathode profile of the tool, x _a and y _a are the coordinates of the corresponding sampling points on the workpiece profile, α and β are the sampling points on the workpiece profile and the coordinate axes X and Y respectively the included angle;

Steps 1-5, polynomial fitting is performed on the obtained coordinates of the cathode profile of the tool to obtain the functional relationship between y and x:

In the formula: K is the order of the polynomial, t ₀ ... t _K is the coefficient of the polynomial, denoted as T;

Steps 1-6, according to the curvature formula and the functional relationship between y and x obtained in steps 1-5, obtain the curvature of each point of the flexible electrode (cathode) during the dynamic deformation of the flexible electrode:

In the formula: y(x)' is the first derivative of y(x, W), and y(x)" is the second derivative of y(x, W);

Step 2. Combining the relationship between the deformation curvature of the flexible electrode and the applied load, the required load during the dynamic deformation of the flexible electrode can be determined; the relationship between the deformation curvature of the flexible electrode and the applied load is established through the following mathematical model :

Step 2-1. After the tool cathode is installed, it can be simplified as a simply supported beam model of length l with one end constrained by a fixed end and one end hinged. The boundary condition is that the deflection is 0 at the hinged support. The length direction is the X-axis, and the radial direction of the tool electrode section is the coordinate system of the Y-axis;

Step 2-2. In the case of pure bending deformation and transverse bending deformation ignoring shear stress, the relationship between bending moment and curvature is:

Where ρ is the curvature, M is the applied load, E is the elastic modulus of the material, I is the moment of inertia, and EI is its bending stiffness; the approximate differential equation of the deflection curve can be obtained by calculation:

where w is the deflection;

Step 2-3, the angular displacement of the cross section to its original position is called the corner of the section, according to the equation of the corner:

Calculated: EIw'=∫M(x)dx+C, where γ is the rotation angle, w' is the first-order derivative of the deflection, and C is the integral constant;

Step 2-4, the deflection equation can be obtained by integrating the above formula:

Further simplified as: EIw=∫∫(M(x)dx)dx+Cx+D, where w is deflection, C and D are integral constants;

Steps 2-5, substituting the boundary conditions into the above formula, the deflection equation can be obtained as:

Among them, M is the applied load, l is the length of the tool electrode, and x is the abscissa of any point of the tool electrode;

Step 2-6, according to the curvature formula, the curvature at any point is obtained as:

in

w' is the first derivative of deflection,

w″ is the second derivative of deflection;

Step 3. According to the model of the deformation curvature of the flexible electrode and the workpiece profile established according to the sampling data of the standard profile of the processed workpiece, the change of the curvature of the flexible electrode corresponding to the profile of the workpiece during the processing is obtained, and then the deformation curvature of the flexible electrode and the applied load are obtained. relationship, to obtain the change of the load on the flexible electrode during processing;

The applied load is calculated by combining the two models, so that the flexible electrode can realize the dynamic deformation of the standard surface of the workpiece during the sweeping process.

The shape of the flexible electrode is a simple tube or rod. By establishing the relationship between the deformation curvature of the flexible electrode and the curvature of the workpiece surface and the relationship between the deformation curvature of the flexible electrode and the load, the flexible electrode can fit the workpiece shape in the sweeping electrolytic machining. The dynamic deformation of the surface makes the processed workpiece surface closer to the ideal surface. The design of the cathode is simplified, and the processing efficiency of workpieces with complex profiles is improved.

The above-mentioned flexible electrode dynamic deformation electrolytic machining method, the flow field is characterized in that: due to the deformation and displacement of the tool electrode during the machining process, in order to avoid adverse phenomena such as liquid shortage areas during the machining process, the flow form of the electrolyte is designed as a side flow type , the flow field is an open or semi-closed flow field, and the electrolyte flows along the axis of the tool cathode by adding an electrolyte supply device.

The above-mentioned flexible electrode dynamic deformation electrolytic machining method is applied to the processing of parts with variable cross-section surfaces. , apply different loads, so that the tool electrode can achieve dynamic deformation to fit the standard profile during the sweeping process, so that the processed workpiece profile is close to the ideal profile, and the processing of parts with variable cross-section profiles is completed.

The above-mentioned flexible electrode dynamic deformation electrolytic machining method is applied to the processing of parts with variable cross-sections, and is characterized in that it is specifically applied to the processing of closed blisks, and the closed blisk blanks are pre-opened according to the distribution position of the blades. The straight hole is convenient for tool electrode installation; in the pre-piercing straight hole, the complex twisted channel of the closed overall blisk is processed through the sweeping electrolytic machining method of the flexible electrode with controllable dynamic deformation.

The above-mentioned flexible electrode dynamic deformation electrolytic machining method is applied to the processing of parts with variable cross-sections, and is characterized in that it is specifically applied in the electrolytic machining of closed integral blisk blade cascade passages, and is characterized in that: the tool electrode (2) passes through the cathode clamp The holding shaft (1) is connected to the processing shaft, and the tool electrode (2) is driven to move through the spatial movement of the processing shaft, and the corresponding load is applied; the workpiece (3) processed by the closed integral blisk is installed on the workpiece rotating table (4), The workpiece (3) processed by the closed integral blisk is driven to rotate by the workpiece rotating table (4); the compound movement of the tool electrode (2) and the closed integral blisk to process the workpiece (3) is used to control the electrolytic machining gap and realize the tool The side wall of the electrode (2) is used as the processing surface, and the sweeping electrolytic machining is carried out along the surface of the complex surface of the workpiece.

Beneficial effect:

Compared with the prior art, the present invention has the following significant advantages.

(1) A dynamic deformation electrolytic machining method for flexible electrodes is provided. Choose a metal material with good corrosion resistance and certain rigidity, which can produce bending deformation when the corresponding load is applied, and make a slender tubular or rod-shaped flexible tool electrode. During processing, the side wall of the tool electrode is used as the processing surface along the complex Sweeping electrolytic machining is carried out on the surface of the profile, and different loads are applied according to the curvature change characteristics of the workpiece profile, so that the tool electrode produces dynamic deformation while feeding, so as to realize complex machining with variable cross-sections such as closed integral blisks. Electrolytic machining of surface parts.

(2) An electrolytic machining method for a closed integral blisk is provided. The dynamic deformation electrolytic machining of flexible electrodes is applied to the machining of closed blisks. The closed integral blisk blank is pre-opened with straight holes equal to the number of blades according to the distribution position of the blades, which is convenient for the installation of flexible electrodes through the straight holes; in the pre-pierced straight holes, through the sweeping electrolytic processing method of controllable dynamic deformation of the flexible electrodes, The complex twisted channel of the closed integral blisk is processed.

(3) The flexibility of the tool electrode is good, and its dynamic deformation can ensure the machining accuracy. The cathode designed in the present invention selects a metal material with good corrosion resistance, certain rigidity and ductility, which can produce bending deformation when a corresponding load is applied, and when the load is removed, the tool electrode rebounds and the deformation recovers. During the processing, according to the curvature change characteristics at different positions of the workpiece surface, different loads are applied to make the tool electrode produce corresponding dynamic deformation at different positions during the feeding process, so that the processed workpiece surface is closer to the ideal. Surface, to ensure processing accuracy.

(4) The cathode design is simplified, and the cathode processing is simple and easy to obtain. The shape of the cathode designed in the present invention is elongated tubular or rod-shaped. Compared with nesting electrolytic machining and radial feed electrolytic machining, the cathode is simple in design, easy to manufacture, easy to replace after the cathode is damaged, shortens the cathode production cycle, and reduces Reduce time cost and improve processing efficiency.

(5) It has a wide range of applications. It can process blades with simple blade profiles and variable cross-section blades. The cathode of the present invention is a slender tubular or rod-shaped tool electrode that can be flexibly deformed. According to the different profiles of the processed workpieces, different loads can be applied according to the curvature change characteristics of the profiles, so that the tool electrodes produce different deformations, thereby performing electrolysis. processing. In addition, the diameter of the flexible electrode can be reduced as much as possible to ensure the processing requirements of narrow channels.

Description of drawings

Figure 1 is a schematic diagram of the electrolytic machining forming rule of the cosθ method;

Fig. 2 is the schematic diagram of tool cathode coordinate system establishment;

Fig. 3 is a schematic diagram of the principle of electrolytic machining at the initial position;

Figure 4 is a schematic diagram of the principle of electrolytic machining during processing;

Figure 5 is a schematic diagram of the deformation principle of the flexible electrode;

The names of the symbols in the figure: 1. The cathode clamping shaft, 2. The tool electrode, 3. The workpiece processed by the closed integral blisk, 4. The workpiece rotating table.

Detailed ways

The specific implementation process of the present invention will be described in detail below by taking the electrolytic machining of the closed integral blisk cascade channel as an example in conjunction with the accompanying drawings.

As shown in Figure 3, taking the electrolytic machining of the closed-type integral blisk cascade channel as an example, the device for implementing "a flexible electrode dynamic deformation electrolytic machining method" of the present invention is mainly composed of the cathode clamping shaft 1, the tool electrode 2, and the closed-type The workpiece 3 is processed by the blisk as a whole, and the workpiece rotary table 4 is composed.

The movement form of the present invention is shown in Figure 4, the tool electrode 2 is connected to the processing shaft through the cathode clamping shaft 1, the tool electrode 2 is driven by the spatial movement of the processing shaft, and the corresponding load is applied at the same time; the closed integral blisk processes the workpiece 3 is installed on the workpiece rotating table 4, and the workpiece 3 is processed by the closed integral blisk to rotate through the workpiece rotating table 4; through the compound movement of the tool electrode 2 and the closed integral blisk to process the workpiece 3, the electrolytic machining gap is controlled to realize the The side wall of the tool electrode 2 is used as the processing surface, and the sweeping electrolytic machining is carried out along the surface of the complex surface of the workpiece.

Preparation of the tool electrode 2 of the present invention. The tool electrode 2 is selected from a metal material with good corrosion resistance, certain rigidity and ductility. When the corresponding load is applied, it can produce bending deformation. When the load is removed, the tool electrode rebounds and the deformation recovers. Its shape is slender Tubular or rod-shaped, flexible electrode deformation principle is shown in Figure 5.

Preparation of the closed integral blisk workpiece 3 of the present invention. Closed integral blisk machining workpiece 3, before electrolytic machining, it is necessary to open through holes equal to the number of blades by mechanical processing, and the width of the through holes should be greater than the diameter of the tool electrode 2.

Due to the deformation and displacement of the tool cathode during the processing, in order to avoid adverse phenomena such as liquid shortage areas during the processing, the electrolyte flow form of the present invention is designed as a side flow type, and the flow field is an open flow field, that is, the external electrolyte supply Liquid device, the electrolyte flows along the axis of the tool cathode.

The following ten steps are required for the process of electrolytic machining of the closed integral blisk cascade channel of the present invention.

Step 1: install the closed-type blisk processing workpiece 3 on the workpiece turntable 4, and connect the closed-type blisk processing workpiece 3 to the positive electrode of the electrolytic processing power supply;

Step 2: The two cathode clamping shafts 1 are vertically installed on the processing shaft that can realize multi-axis linkage, and the processing shaft is connected to the negative electrode of the electrolytic processing power supply;

Step 3: Move the two cathode clamping shafts 1 through the movement of the processing shaft, so that the axis of the cathode clamping shaft coincides with a certain straight hole opened by the workpiece 3 of the closed integral blisk, presenting "cathode clamping shaft 1-closed The "upper-middle-lower" form of the overall blisk machining workpiece 3-cathode clamping shaft 1";

Step 4: The tool electrode 2 passes through the through hole of the closed integral blisk to process the workpiece 3, and the two ends are respectively connected to the two cathode clamping shafts 1. When connecting, the lower end of the tool electrode 2 is constrained by the fixed end, and the upper end is constrained by the hinge support ;

Step 5: Detect and check the position of the previously installed parts;

Step 6: through the relative movement of the machining axis and the workpiece turntable 4, the tool electrode 2 is moved to the initial position at the vane basin of the cascade channel;

Step 7: The processing axis is fed under the setting parameters of the blade basin surface, the initial load is applied, and the tool electrode 2 produces corresponding bending deformation to reach the predetermined initial shape;

Step 8: Put in the electrolyte, turn on the electrolytic machining power supply, the tool electrode 2 is driven by the machining axis to move along the radial movement of the closed integral blisk to process the workpiece 3, and at the same time, the machining axis moves toward the The tool electrode 2 applies a load to cause dynamic deformation of the tool electrode 2, and the closed integral blisk machining workpiece 3 rotates under the drive of the workpiece turntable 4, thereby generating compound motion, and finally completing the processing of the blade basin surface of the cascade channel;

Step 9: After the surface processing of the leaf basin is completed, disconnect the electrolytic processing power supply, stop the electrolyte supply, remove the load, the deformation of the tool electrode 2 recovers and move to the back of the leaf cascade channel, and the machining axis is set under the parameters of the back of the leaf. Apply an initial load to the tool electrode 2, and the tool electrode 2 will produce a corresponding bending deformation to reach the predetermined initial shape; when the electrolyte is connected, the electrolytic machining power supply is connected, and the tool electrode 2 is driven by the machining axis to process the workpiece 3 diameters along the closed integral blisk. At the same time, the processing axis applies load to the tool electrode 2 under the setting parameters of the back of the blade, so that the tool electrode 2 produces dynamic deformation, and the workpiece 3 processed by the closed integral blisk rotates under the drive of the workpiece turntable 4, thereby generating compound motion , and finally complete the processing of the back of the cascade channel leaf;

Step 10: After processing, disconnect the electrolytic processing power supply, stop the electrolyte supply, remove the load, the deformation of the tool electrode 2 recovers and change to the next straight hole, and repeat the above steps in sequence until the workpiece 3 is processed by the closed integral blisk. All cascade passages are electrolytically machined.

Claims

A dynamic deformation electrolytic processing method for a flexible electrode, which is characterized in that it includes the following process: using a corrosion-resistant tubular or rod-shaped metal that meets rigid requirements, but can be bent and deformed when a corresponding load is applied, and recovers when the load is removed. Processed tool electrodes;

When processing complex profiles, the side wall of the tool electrode is used as the processing surface to carry out sweeping electrolytic machining along the surface of the complex profile of the workpiece; Dynamic deformation occurs while feeding, and the deformed shape is similar to the mathematical model of the workpiece surface line, so that the processed workpiece surface is close to the ideal surface.
The method for dynamic deformation electrolytic machining of flexible electrodes according to claim 1, characterized in that it comprises the following processes:

Step 1. According to the sampling data of the standard surface of the processed workpiece, the relationship between the deformation curvature of the flexible electrode and the curvature of the workpiece surface is established. The mathematical model establishment process is as follows:

Step 1-1. Sampling the surface of the processed workpiece, using the cosθ method to study its electrolytic machining forming law, and simplifying and approximating the complex electric field in the actual machining gap, mainly based on the following assumptions:

(1) The potential gradient along the direction of the current line remains unchanged, that is, the electric field intensity on the same current line is the same;

(2) Starting from the equipotential surface of the anode to the equipotential surface of the cathode, the potential gradually decreases, and the equipotential surface is orthogonal to the current line;

(3) The conductivity κ of the electrolyte in the processing gap is evenly distributed;

Step 1-2. After simplifying the approximate processing, according to the basic principles of electrolytic machining such as Ohm's law and Faraday's law, the equations related to the forming law are obtained:

U R =U-δE

v a = ηωi

In the formula: U R is the voltage drop in the gap electrolyte; U is the voltage between the cathode and the anode; δE is the sum of the cathode and anode potential values; i is the current density; κ is the conductivity of the electrolyte; Δ is the processing gap ; v a is the workpiece electrolysis speed; η is the current efficiency; ω is the volume electrochemical equivalent;

Step 1-3. When the electrolytic machining reaches the equilibrium state, the electric field parameter no longer changes with time, but is only a function of the spatial position, that is, the gap electric field is a steady electric field; according to Ohm's law and Faraday's law, establish the relevant workpiece electrolysis speed v a The basic equation: v a = vcosθ, simultaneous equations, deduce the calculation formula of the machining gap Δ:

In the formula: v is the feed speed of the cathode; θ is the angle between the normal direction of the workpiece surface and the feed direction of the cathode; Δ b is the balance machining gap;

Steps 1-4. Since the cathode of the tool is a slender tubular or rod-shaped electrode for sweeping electrolytic machining, the cathode of the tool is simplified into a two-dimensional curve, and the sweeping process of the curve is the workpiece surface to be processed; therefore, in During the dynamic deformation of the flexible electrode, the coordinate relationship between each point of the flexible electrode, that is, the cathode of the tool, and the corresponding sampling point on the workpiece surface is:

x=x a -Δcosα

y=y a -Δcosβ

In the formula: x and y are the coordinates of a certain point on the cathode profile of the tool, x a and y a are the coordinates of the corresponding sampling points on the workpiece profile, α and β are the sampling points on the workpiece profile and the coordinate axes X and Y respectively the included angle;

Steps 1-5, polynomial fitting is performed on the obtained coordinates of the cathode profile of the tool to obtain the functional relationship between y and x:

In the formula: K is the order of the polynomial, t 0 ... t K is the coefficient of the polynomial, denoted as T;

Steps 1-6, according to the curvature formula and the functional relationship between y and x obtained in steps 1-5, the curvature of each point of the flexible electrode during the dynamic deformation process of the flexible electrode is obtained:

In the formula: y(x)' is the first derivative of y(x, W), and y(x)" is the second derivative of y(x, W);

Step 2. Combining the relationship between the deformation curvature of the flexible electrode and the applied load, the required load during the dynamic deformation of the flexible electrode can be determined; the relationship between the deformation curvature of the flexible electrode and the applied load is established through the following mathematical model :

Step 2-1. After the installation of the tool cathode is completed, simplify it to a simply supported beam model of length l with one end constrained by a fixed end and one end hinged. The direction is the X axis, and the radial direction of the tool electrode section is the coordinate system of the Y axis;

Step 2-2. In the case of pure bending deformation and transverse bending deformation ignoring shear stress, the relationship between bending moment and curvature is:
Where ρ is the curvature, M is the applied load, E is the elastic modulus of the material, I is the moment of inertia, and EI is its bending stiffness; the approximate differential equation of the deflection curve can be obtained by calculation:
where w is the deflection;

Step 2-3, the angular displacement of the cross section to its original position is called the corner of the section, according to the equation of the corner:
Calculated: EIw'=∫M(x)dx+C, where γ is the rotation angle, w' is the first-order derivative of the deflection, and C is the integral constant;

Step 2-4, the deflection equation can be obtained by integrating the above formula:
Further simplified as: EIw=∫∫(M(x)dx)dx+Cx+D, where w is deflection, C and D are integral constants;

Steps 2-5, substituting the boundary conditions into the above formula, the deflection equation can be obtained as:
Among them, M is the applied load, l is the length of the tool electrode, and x is the abscissa of any point of the tool electrode;

Step 2-6, according to the curvature formula, the curvature at any point is obtained as:
in
w' is the first derivative of deflection,
is the second derivative of the deflection;

Step 3. According to the model of the deformation curvature of the flexible electrode and the workpiece profile established according to the sampling data of the standard profile of the processed workpiece, the change of the curvature of the flexible electrode corresponding to the profile of the workpiece during the processing is obtained, and then the deformation curvature of the flexible electrode and the applied load are obtained. relationship, to obtain the change of the load on the flexible electrode during processing;

The applied load is calculated by combining the two models, so that the flexible electrode can realize the dynamic deformation of the standard surface of the workpiece during the sweeping process.
The method for dynamic deformation electrolytic machining of flexible electrodes according to claim 1, characterized in that: due to the deformation and displacement of the tool electrode during the machining process, in order to avoid the disadvantageous phenomenon of the lack of liquid area during the machining process, the flow form of the electrolyte is side flow Type, the flow field is an open or semi-closed flow field, through the addition of an electrolyte supply device, the electrolyte flows along the axis of the tool cathode.
According to any one of claims 1 to 3, the dynamic deformation electrolytic machining method of flexible electrodes is applied to the processing of parts with variable cross-sections, and is characterized in that: install the tool electrode and the workpiece to be processed, and adjust their positional relationship reasonably, according to the processed According to the curvature change characteristics of the variable cross-section surface parts, different loads are applied to make the tool electrode realize the dynamic deformation of the standard surface during the sweeping process, so that the processed workpiece surface is close to the ideal surface. Complete the machining of parts with variable cross-section surfaces.
According to claim 4, the dynamic deformation electrolytic machining method of flexible electrodes is applied to the processing of parts with variable cross-section profiles, and is characterized in that it is specifically applied to the processing of closed blisks, and the blanks of the closed blisks are distributed according to blades The position is pre-opened with straight holes equal to the number of blades, which is convenient for tool electrode installation; in the pre-pierced straight holes, through the sweeping electrolytic machining method with controllable dynamic deformation of flexible electrodes, the complex twisted channel of the closed overall blisk is processed.
According to claim 4, the flexible electrode dynamic deformation electrolytic machining method is applied to the processing of parts with variable cross-sectional surfaces, and is characterized in that it is specifically applied in the electrolytic machining of closed integral blisk blade cascade channels, and is characterized in that: tool electrodes (2) The cathode clamping shaft (1) is connected to the processing shaft, and the tool electrode (2) is driven by the spatial movement of the processing shaft, and the corresponding load is applied; the workpiece (3) processed by the closed integral blisk is installed on the workpiece to rotate On the table (4), the workpiece (3) processed by the closed blisk is driven by the workpiece rotating table (4) to rotate; through the compound movement of the tool electrode (2) and the workpiece (3) processed by the closed blisk, the electrolysis is controlled. The machining gap realizes the sweeping electrolytic machining along the surface of the workpiece with the side wall of the tool electrode (2) as the machining surface.