Design method of weak-rigidity tool electrode for electric spark machining

Abstract

The invention discloses a design method of a weak-rigidity tool electrode for electric spark machining. The method comprises the following steps: firstly, constructing an initial three-dimensional model of a tool electrode by adopting an equal-gap offset method according to a target molded surface of a workpiece, and manufacturing an electrode according to the initial three-dimensional model for trial machining; the undercut area and the undercut amount relative to the target profile are obtained by measuring the actual profile of the workpiece. Based on the undercut amount, reversely deducing the actual geometrical shape of stress deformation of the tool electrode in the machining process, and determining the equivalent distribution load acting on the working surface of the tool electrode through finite element simulation iteration. Then, the initial model is simulated according to the load, and the reverse compensation amount of the working surface required for counteracting deformation is calculated. And finally, the model is corrected according to the compensation amount, and a final electrode three-dimensional model is obtained and manufactured. According to the invention, the problem of undercut of a workpiece caused by deformation of a weak-rigidity electrode under the action of discharge force is effectively solved, the machining precision and the qualified rate are remarkably improved, and the time and the cost for repeatedly trimming the electrode are reduced.

Description

Technical Field

[0001] This invention relates to the field of electrical discharge machining technology, specifically to a design method for a weakly rigid tool electrode in electrical discharge machining. Background Technology

[0002] Electrical discharge machining (EDM) utilizes pulsed discharge between the electrode of the forming tool and the workpiece to remove material, enabling high-precision and high-stability machining of complex cavities and holes in various conductive materials. Therefore, it is widely used in advanced manufacturing fields such as aviation, aerospace, weaponry, and precision molds.

[0003] In these applications, it is often necessary to machine deep, narrow cavities or holes with large aspect ratios and complex shapes. To ensure machining accessibility and avoid interference, tool electrodes are often designed as slender, thin-walled, and weakly rigid structures. During electrical discharge machining (EDM), the electrode typically needs to translate to smooth the sidewalls of the cavity or hole. However, under these conditions, different working surfaces on the tool electrode will periodically bear the dynamic fluid pressure load generated by the discharge products within the machining gap. Due to the insufficient rigidity of the electrode itself, significant elastic bending deformation will occur under asymmetric loads, causing its working surface to deviate from its theoretical position. Ultimately, this results in the actual machined surface of the workpiece shifting outward relative to the target surface, thus creating undercut defects.

[0004] Because the load on the tool electrode during electrical discharge machining (EDM) is difficult to determine accurately, the mainstream approach in the industry is currently a trial-and-error method: based on the measured undercut results of the machined workpiece, and relying on the experience of the process engineers, the initial position of the electrode is manually adjusted or local grinding is performed, followed by another machining verification. This process often requires multiple iterations, which is not only time-consuming and labor-intensive, but also highly dependent on the operator's experience. Furthermore, repeated clamping and grinding can introduce new errors, potentially leading to the scrapping of the workpiece or electrode. This method has a long processing cycle, high cost, and difficulty in guaranteeing consistent accuracy, becoming a key bottleneck restricting the efficiency and quality of high-precision, complex-cavity EDM. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for weakly rigid tool electrodes in electrical discharge machining (EDM) to solve the technical problems in the prior art, such as the easy deformation of the tool electrode during machining, which leads to undercutting of the workpiece.

[0006] To achieve the above objectives, the technical solution provided by this invention is: a method for designing a weakly rigid tool electrode for electrical discharge machining, comprising the following steps: S1: Based on the target surface of the workpiece, the shape of the tool electrode is designed using the equal gap offset method, and the initial three-dimensional model of the tool electrode is constructed. S2: Based on the initial three-dimensional model, manufacture a tool electrode, use the tool electrode to perform trial processing on the workpiece, measure the actual surface of the workpiece after the trial processing, and obtain its undercut area and undercut amount relative to the target surface; S3: Based on the undercut amount of the actual workpiece surface, determine the actual geometric shape of the working surface of the tool electrode due to stress deformation during the trial machining process, and obtain the distributed load acting on the working surface of the tool electrode through finite element simulation. S4: Perform finite element simulation on the initial three-dimensional model based on distributed load, and calculate the amount of reverse compensation required to offset the deformation on the working surface of the initial three-dimensional model. S5: Adjust the initial three-dimensional model according to the reverse compensation amount to obtain the final tool electrode three-dimensional model that meets the workpiece processing requirements, and manufacture the tool electrode based on the final tool electrode three-dimensional model.

[0007] To optimize the above technical solution, the specific measures also include: In step S1, the step of designing the tool electrode shape using the equal gap offset method and constructing the initial three-dimensional model of the tool electrode specifically includes: offsetting each point on the target surface of the workpiece outward along the outward normal direction of that point by a preset discharge gap value, and using the offset point set to reconstruct the surface as the working surface of the tool electrode, thereby completing the construction of the initial three-dimensional model.

[0008] In step S2, obtaining the undercut region and undercut amount relative to the target surface specifically includes: Multiple measurement points are selected on the actual surface of the workpiece. For each measurement point, the normal distance from the point along the normal direction to the target surface is calculated. Furthermore, subtract the unidirectional profile tolerance value of the target surface at that point from the normal distance to obtain the undercut at that point; The region containing all points with a cut value greater than zero is defined as the undercut region.

[0009] In step S3, determining the actual geometric shape of the working surface of the tool electrode formed by the deformation due to force during the trial machining process specifically includes: Select on the actual surface of the workpiece N A set of measurement points is formed. P i}( i =1,2,3… N ); Passing point P i Draw its outer normal, which intersects the theoretical position of the tool electrode working surface in the initial 3D model at point [point missing]. P i Let N intersection points be denoted as the point set { P i'}; Furthermore, based on the point P i undercut t pi , will point P i 'Distance of movement along the outer normal direction into the tool electrode body t pi Get points P i '', will the point set { P i After processing using the above method, the point set { is obtained} P i ''}; From the point set { P i The fitted surface serves as the actual geometric shape of the working surface of the tool electrode under stress deformation during trial machining.

[0010] In step S3, obtaining the distributed load acting on the working surface of the tool electrode through finite element simulation specifically includes: The initial 3D model is modeled using finite element methods, and material properties and boundary conditions are set. Furthermore, using the actual geometry of the tool electrode working surface as the simulation target, a distributed load is applied to the tool electrode working surface for finite element simulation. In the finite element model, the point set { is extracted. P i The normal deformation of the node corresponding to each point is denoted as '} ; The deviation coefficient is calculated using the following formula:

[0011] Furthermore, the values ​​of the distributed load are adjusted and iterative simulations are performed until the deviation coefficient is reached. If the value is less than the bidirectional tolerance of the profile of the target surface of the workpiece, the applied distributed load value is the distributed load acting on the working surface of the tool electrode.

[0012] In step S4, the calculation of the reverse compensation amount required to offset the deformation on the initial three-dimensional model working surface is specifically as follows: Set a set of initial reverse compensation values ​​for the working surface of the initial 3D model of the tool electrode, and construct an optimized tool electrode model; In the finite element simulation software, the distributed load of step S3 is applied to the working surface of the optimized tool electrode model, and its deformation geometry under the distributed load is simulated and calculated. Based on the comparison between the simulation deformation results and the target surface, the reverse compensation amount is iteratively adjusted and the above simulation steps are repeated until the iteration terminates, so as to obtain the reverse compensation amount that meets the workpiece processing requirements and the corresponding final tool electrode three-dimensional model.

[0013] If the shape of the working surface of the tool electrode after simulation deformation is reversed to the workpiece profile through equal gap offset, and the predicted machining result shows overcutting, then the current reverse compensation amount is reduced; if the predicted machining result still shows undercutting, then the current reverse compensation amount is increased; until the predicted machining result meets the workpiece contour requirements, the iteration terminates.

[0014] In step S3, the distributed load acting on the working surface of the tool electrode is a uniformly distributed load, and the direction of the load is perpendicular to the working surface of the tool electrode and points into the interior of the tool electrode entity.

[0015] When selecting measurement points on the actual surface of the workpiece, a non-uniform selection strategy is adopted: increase the density of measurement points in areas with large curvature changes of the target surface, and decrease the density of measurement points in areas with gentle curvature changes.

[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention achieves precise quantification and compensation of the deformation behavior of tool electrodes under complex discharge loads through mathematical modeling and finite element simulation. First, the actual geometric shape of the electrode after deformation under stress is deduced based on the measured undercut amount of the workpiece. Then, the equivalent distributed load is iteratively simulated. Finally, the initial electrode model is optimized by reverse compensation based on this load, which significantly improves the forming accuracy of the final manufactured electrode. This fundamentally solves the problem of undercut of workpieces caused by deformation of weak rigid electrodes, and effectively improves the processing qualification rate and first-time success rate of parts.

[0017] This invention possesses universality and strong engineering applicability, applicable to machining scenarios involving deep and narrow cavities of varying shapes and sizes. By replacing numerous physical experiments with finite element simulation, it not only reduces resource consumption but also predicts and guarantees the performance of the physical electrodes before manufacturing. Furthermore, the non-uniform measurement point selection strategy proposed in this invention can adaptively adapt to changes in surface curvature, ensuring higher compensation accuracy in geometrically critical regions and enhancing the robustness of the method when handling complex surfaces.

[0018] This invention combines trial processing with finite element simulation to perform precise reverse compensation design on the working surface of the tool electrode, which greatly shortens the process debugging cycle and significantly reduces the time and manufacturing costs caused by repeated trial and error.

[0019] This invention can reduce the technical threshold and dependence on operator experience in electrical discharge machining, especially precision cavity machining. It transforms the electrode trimming process, which relies on craftsman experience, into a calculable, repeatable, and standardized design process, which is conducive to the accumulation and reuse of process knowledge. This not only stabilizes product quality but also provides reliable technical support for enterprises to achieve efficient and low-cost batch or single-piece precision manufacturing. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the workflow in an embodiment of the present invention.

[0021] Figure 2 This is the tool electrode initialization three-dimensional model designed in the embodiments of the present invention.

[0022] Figure 3 This is a schematic diagram of the load applied to the working surface of the tool electrode initialization three-dimensional model in an embodiment of the present invention.

[0023] Figure 4 This is a deformation diagram of the working surface of the tool electrode in an embodiment of the present invention under a uniformly distributed load of 10 Pa.

[0024] Figure 5 This is a deformation diagram of the optimized tool electrode in electrical discharge machining according to an embodiment of the present invention.

[0025] Figure 2 In the middle: 1-Working surface of the tool electrode; 2-Clamping area of ​​the tool electrode; 3-First discrete point on the working surface of the tool electrode; 4-Second discrete point on the working surface of the tool electrode; 5-Third discrete point on the working surface of the tool electrode. Detailed Implementation

[0026] The present invention will be further described in detail below through specific embodiments, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0027] In some implementations, such as Figure 1 As shown, this invention provides a method for designing a weakly rigid tool electrode for electrical discharge machining, comprising the following steps: S1: Based on the target surface of the workpiece, the shape of the tool electrode is designed using the equal gap offset method, and the initial three-dimensional model of the tool electrode is constructed. In some implementations, the equal gap offset method specifically involves offsetting each point on the target surface of the workpiece outward along the direction of the outward normal at that point by a preset discharge gap value, and using the offset point set to reconstruct the surface as the working surface of the tool electrode to complete the construction of the initial three-dimensional model.

[0028] Graphite should be the preferred material for tool electrodes, provided that the surface quality of the workpiece can be guaranteed. The shape design of the tool electrode should prioritize ensuring the rigidity of the tool electrode.

[0029] S2: Based on the initial three-dimensional model, manufacture a tool electrode, use the tool electrode to perform trial processing on the workpiece, measure the actual surface of the workpiece after the trial processing, and obtain its undercut area and undercut amount relative to the target surface; In step S2, the undercut region and undercut amount relative to the target surface are obtained, specifically including: Select multiple measurement points on the actual surface of the workpiece, and for each measurement point, calculate its normal distance from the target surface along the normal direction. Preferably, the undercut at that point is obtained by subtracting the one-way profile tolerance value of the target surface from the normal distance; The region containing all points with a cut value greater than zero is defined as the undercut region.

[0030] S3: Based on the undercut amount of the actual workpiece surface, determine the actual geometric shape of the working surface of the tool electrode due to stress deformation during the trial machining process, and obtain the distributed load acting on the working surface of the tool electrode through finite element simulation. In step S3, the actual geometric shape of the working surface of the tool electrode due to stress deformation during the trial machining process is determined, specifically including: In some implementations, selection is made on the actual surface of the workpiece. N A set of measurement points is formed. P i}( i =1,2,3… N ); Passing point P i Draw its outer normal, which intersects the theoretical position of the tool electrode working surface in the initial 3D model at point [point missing]. P i Let N intersection points be denoted as the point set { P i '}; According to the point P i undercut t pi , will point P i 'Distance of movement along the outer normal direction into the tool electrode body t pi Get points P i '', will the point set { P i After processing using the above method, the point set { is obtained} Pi ''}; From the point set { P i The fitted surface serves as the actual geometric shape of the working surface of the tool electrode under stress deformation during trial machining.

[0031] In some implementations, a non-uniform selection strategy is adopted when selecting measurement points on the actual surface of the workpiece: the density of measurement points is increased in areas where the curvature of the target surface changes greatly, and the density of measurement points is reduced in areas where the curvature changes gently, so as to more accurately characterize the distribution of undercut.

[0032] In step S3, the distributed load acting on the working surface of the tool electrode is obtained through finite element simulation, specifically including: The initial 3D model is modeled using finite element methods, and material properties and boundary conditions are set. Using the actual geometry of the tool electrode working surface as the simulation target, a distributed load is applied to the tool electrode working surface for finite element simulation. In the finite element model, the point set { is extracted. P i The normal deformation of the node corresponding to each point is denoted as '} ; The deviation coefficient is calculated using the following formula:

[0033] Preferably, the value of the distributed load is adjusted and iterative simulation is performed until the deviation coefficient is reached. If the value is less than the bidirectional tolerance of the profile of the target surface of the workpiece, the applied distributed load value is the distributed load acting on the working surface of the tool electrode.

[0034] In some embodiments, the distributed load acting on the working surface of the tool electrode is a uniformly distributed load, and the direction of the load is perpendicular to the working surface of the tool electrode and points into the interior of the tool electrode body.

[0035] S4: Perform finite element simulation on the initial three-dimensional model based on distributed load, and calculate the amount of reverse compensation required to offset the deformation on the working surface of the initial three-dimensional model. In step S4, the amount of reverse compensation required to offset deformation on the working surface of the initial 3D model is calculated, specifically as follows: Set a set of initial reverse compensation values ​​for the working surface of the initial 3D model of the tool electrode, keep the shape of the non-working surface of the initial 3D model of the tool electrode unchanged, and construct an optimized tool electrode model by using the working surface and the non-working surface to build a solid. In the finite element simulation software, the distributed load of step S3 is applied to the working surface of the optimized tool electrode model, and its deformation geometry under the distributed load is simulated and calculated. Based on the comparison between the simulation deformation results and the target surface, the reverse compensation amount is iteratively adjusted and the above simulation steps are repeated until the iteration terminates, so as to obtain the reverse compensation amount that meets the workpiece processing requirements and the corresponding final tool electrode three-dimensional model.

[0036] In some implementations, if the shape of the working surface of the tool electrode after simulation deformation is back-inferred to the workpiece profile through equal gap offset, and the predicted machining result shows overcutting, then the current reverse compensation amount is reduced; if the predicted machining result still shows undercutting, then the current reverse compensation amount is increased; until the predicted machining result meets the workpiece contour requirements, the iteration terminates.

[0037] S5: Adjust the initial three-dimensional model according to the reverse compensation amount to obtain the final tool electrode three-dimensional model that meets the workpiece processing requirements, and manufacture the tool electrode based on the final tool electrode three-dimensional model.

[0038] This invention eliminates the need to adjust the tool electrode pose. It only requires a set of trial machining results to obtain the tool electrode shape that meets the workpiece machining requirements by reverse compensation of the working surface of the tool electrode. Moreover, the trial machining process does not lead to the scrapping of the workpiece. It has high design efficiency, low design cost, reliable method and engineering application value.

[0039] In this embodiment, a part has multiple deep and narrow internal cavities with a surface profile tolerance of 0.1 mm. Due to the narrowness and high curvature of the internal cavities, machining accessibility is poor, and straight shank tools are difficult to use for interference-free machining. Therefore, electrical discharge machining (EDM) is required, necessitating the design of a tool electrode. The design process is as follows: The tool electrode was designed using the equal gap method, and its initial 3D model is shown below. Figure 2 The tool electrode material is selected as graphite, and the tool electrode is manufactured using a CNC engraving and milling machine.

[0040] A CNC machining program was created to perform roughing and finishing on the first inner cavity of the workpiece using two identical tool electrodes. After finishing, a coordinate measuring machine was used to measure the machined surface of the workpiece's inner cavity (this working surface was shaped by the working surface of the tool electrodes). The inspection results showed that the machined surface of the workpiece's inner cavity was generally undercut. Figure 2 The undercut at the first discrete point on the working surface of the tool electrode is approximately 0.3 mm, the undercut at the second discrete point is approximately 0.2 mm, and the undercut at the third discrete point is approximately 0.1 mm. Analysis shows that the load on the tool electrode during electrical discharge machining is as follows: Figure 3As shown. The load acting on the working surface of the tool electrode during electrical discharge machining is estimated using finite element simulation. The method is as follows: In the finite element simulation software ANSYS Workbench, the initial three-dimensional model of the tool electrode is modeled using finite element methods. The tool electrode material is selected as graphite, the elastic modulus is set to 6.2 GPa, and the Poisson's ratio is set to 0.3. In the finite element model, fixed constraints are set for the clamping area of ​​the initial three-dimensional model of the tool electrode, and a uniformly distributed load of 100 Pa is set on the working surface. Figure 4 The deformation diagram of the working surface of the tool electrode initialization 3D model under a uniformly distributed load of 100 Pa is obtained from... Figure 4 It can be seen that the deformation of the first discrete point on the working surface of the tool electrode is about 0.3 mm, the deformation of the second discrete point on the working surface of the tool electrode is about 0.19 mm, and the deformation of the third discrete point on the working surface of the tool electrode is about 0.1 mm. According to the principle of electrical discharge machining, if the electrode is manufactured and the workpiece is machined based on the above-mentioned tool electrode initialization three-dimensional model, the undercut of the machined surface of the workpiece cavity should be 0.1~0.3 mm, which is consistent with the experimental results. The load on the working surface of the tool electrode initialization three-dimensional model in electrical discharge machining is about 100 Pa.

[0041] According to the method for setting the reverse compensation amount of the working surface of the tool electrode initialization three-dimensional model proposed in this invention, in Figure 2 A reverse compensation amount of 0.3 mm is applied to the first discrete point on the working surface of the tool electrode, 0.2 mm to the second discrete point, and 0.1 mm to the third discrete point. The geometry of the non-working surface remains unchanged, thus obtaining an optimized 3D model of the tool electrode. Then, a uniformly distributed load of 100 Pa is applied to the working surface of the optimized 3D model of the tool electrode in ANSYS Workbench, and finite element simulation is performed. The results are as follows. Figure 5 As shown. In Figure 5 In the process, the deformation amounts of the first discrete point, the second discrete point, and the third discrete point on the working surface of the tool electrode are approximately 0.29 mm, 0.19 mm, and 0.1 mm, respectively. Subtracting the corresponding reverse compensation amount from the above deformation amounts, the net deformation amounts of the first discrete point, the second discrete point, and the third discrete point on the working surface of the optimized tool electrode three-dimensional model are approximately -0.01 mm, -0.01 mm, and 0 mm, respectively. According to the principle of electrical discharge machining, the surface profile of the machined surface of the corresponding workpiece cavity can meet the tolerance requirements.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent substitutions, and improvements made by those skilled in the art to the above embodiments without departing from the scope of the technical solution of the present invention, based on the technical essence of the present invention, shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for designing a weakly rigid tool electrode for electrical discharge machining, characterized in that, Includes the following steps: S1: Based on the target surface of the workpiece, the shape of the tool electrode is designed using the equal gap offset method, and the initial three-dimensional model of the tool electrode is constructed. S2: Based on the initial three-dimensional model, manufacture a tool electrode, use the tool electrode to perform trial processing on the workpiece, measure the actual surface of the workpiece after the trial processing, and obtain its undercut area and undercut amount relative to the target surface; S3: Based on the undercut amount of the actual workpiece surface, determine the actual geometric shape of the working surface of the tool electrode due to stress deformation during the trial machining process, and obtain the distributed load acting on the working surface of the tool electrode through finite element simulation. S4: Perform finite element simulation on the initial three-dimensional model based on distributed load, and calculate the amount of reverse compensation required to offset the deformation on the working surface of the initial three-dimensional model. S5: Adjust the initial three-dimensional model according to the reverse compensation amount to obtain the final tool electrode three-dimensional model that meets the workpiece processing requirements, and manufacture the tool electrode based on the final tool electrode three-dimensional model.

2. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 1, characterized in that: In step S1, the step of designing the tool electrode shape using the equal gap offset method and constructing the initial three-dimensional model of the tool electrode specifically includes: offsetting each point on the target surface of the workpiece outward along the outward normal direction of that point by a preset discharge gap value, and using the offset point set to reconstruct the surface as the working surface of the tool electrode, thereby completing the construction of the initial three-dimensional model.

3. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 1, characterized in that: In step S2, obtaining the undercut region and undercut amount relative to the target surface specifically includes: Multiple measurement points are selected on the actual surface of the workpiece. For each measurement point, the normal distance from the point along the normal direction to the target surface is calculated. Subtract the unidirectional profile tolerance value of the target surface at that point from the normal distance to obtain the undercut at that point; The region containing all points with a cut value greater than zero is defined as the undercut region.

4. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 1, characterized in that: In step S3, determining the actual geometric shape of the working surface of the tool electrode formed by the deformation due to force during the trial machining process specifically includes: Select on the actual surface of the workpiece N A set of measurement points is formed. P i }( i =1,2,3… N ); Passing point P i Draw its outer normal, which intersects the theoretical position of the tool electrode working surface in the initial 3D model at point [point missing]. P i Let N intersection points be denoted as the point set { P i '}; According to the point P i undercut t pi , will point P i 'Distance of movement along the outer normal direction into the tool electrode body t pi Get points P i '', will the point set { P i After processing using the above method, the point set { is obtained} P i ''}; From the point set { P i The fitted surface is the actual geometric shape of the working surface of the tool electrode under stress and deformation during trial machining.

5. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 4, characterized in that: In step S3, the distributed load acting on the working surface of the tool electrode is obtained through finite element simulation. The specific steps include: Finite element modeling was performed on the initial three-dimensional model of the tool electrode, and material properties and boundary conditions were set. Using the actual geometry of the tool electrode working surface as the final simulation target, a distributed load is applied to the tool electrode working surface for finite element simulation. In the finite element simulation results of the tool electrode, the point set { is extracted. P i The normal deformation of the node corresponding to each point is denoted as '} ; The deviation coefficient is calculated using the following formula: Adjust the value of the distributed load and perform iterative simulations until the deviation coefficient is reached. The value of the distributed load applied is less than the bidirectional tolerance value of the profile of the target surface of the workpiece. At this time, the value of the distributed load is the distributed load acting on the working surface of the tool electrode during electrical discharge machining.

6. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 1, characterized in that: In step S4, the calculation of the reverse compensation amount required to offset the deformation on the initial three-dimensional model working surface is specifically as follows: Set a set of initial reverse compensation values ​​for the working surface of the initial 3D model of the tool electrode, and construct an optimized tool electrode model; In the finite element simulation software, the distributed load of step S3 is applied to the working surface of the optimized tool electrode model, and its deformation geometry under the distributed load is simulated and calculated. Based on the comparison between the simulation deformation results and the target surface, the reverse compensation amount is iteratively adjusted and the above simulation steps are repeated until the iteration terminates, so as to obtain the reverse compensation amount that meets the workpiece processing requirements and the corresponding final tool electrode three-dimensional model.

7. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 6, characterized in that: If the shape of the working surface of the tool electrode after simulation deformation is reversed to the workpiece profile through equal gap offset, and the predicted machining result shows overcutting, then the current reverse compensation amount is reduced; if the predicted machining result still shows undercutting, then the current reverse compensation amount is increased; until the predicted machining result meets the workpiece contour requirements, the iteration terminates.

8. The method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 1, characterized in that: In step S3, the distributed load acting on the working surface of the tool electrode is a uniformly distributed load, and the direction of the load is perpendicular to the working surface of the tool electrode and points into the interior of the tool electrode entity.

9. A method for designing a weakly rigid tool electrode for electrical discharge machining according to claim 3 or 4, characterized in that: When selecting measurement points on the actual surface of the workpiece, a non-uniform selection strategy is adopted: increase the density of measurement points in areas with large curvature changes of the target surface, and decrease the density of measurement points in areas with gentle curvature changes.

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