Method and system for optimizing feeding path and tool electrode design of electrical discharge coarse machining in bending and torsion runner

Abstract

The application discloses a kind of bending torsion runner electric spark rough machining feed path and tool electrode design optimization method and system, for closed integral blade disk bending torsion runner electric spark rough machining, replace complex space feed path with linear feed, remove runner excess size by calculating tool electrode different linear feed direction, with tool electrode linear feed removes the maximum workpiece runner excess as optimization target, determine optimal electrode linear feed path and electrode shape by particle swarm optimization algorithm iterative optimization.The application combines particle swarm optimization algorithm and three-dimensional model software secondary development technology, simplifies the design work of bending torsion runner electric spark rough machining feed path and electrode shape, realizes the mass removal of workpiece excess, improves rough machining efficiency, and provides new ideas and methods for the improvement of electric spark machining efficiency of closed integral blade disk parts with bending torsion runner characteristics.

Description

Technical Field

[0001] This invention relates to the field of electrical discharge machining technology, specifically to a method and system for optimizing the feed path and tool electrode design in curved and twisted flow channel electrical discharge roughing. Background Technology

[0002] Closed integral bladed disks play a crucial role in aerospace, energy, and industrial production, significantly improving system efficiency and reliability. These disks feature a semi-enclosed, tortuous flow channel and typically operate under high temperature, high pressure, and high speed conditions. They are manufactured using difficult-to-machine metals such as titanium alloys and nickel-based alloys, making them challenging to process using traditional methods.

[0003] Electrical discharge machining (EDM) is a machining technique that uses pulsed electrical discharges to remove excess material. Its advantages include being unaffected by the mechanical properties of the workpiece material, having no macroscopic machining forces, low electrode wear, no tool marks or burrs on the workpiece surface, and high machining accuracy, making it uniquely advantageous for machining difficult-to-machine materials such as high-temperature alloys. Compared to traditional machining methods, EDM allows the tool electrode (tool) to be designed into the shape of a flow channel for electrical discharge forming, replicating the electrode shape on the workpiece. This results in high machining accuracy and lower cost. Therefore, EDM is widely used in the machining of closed, integral bladed disk-type parts.

[0004] In the process of EDM machining of closed integral bladed disk parts, due to the forming requirements of the flow channel surface, the tool electrode has a twisted shape similar to the flow channel structure, which requires a corresponding complex spatial feed trajectory to complete the machining. In actual machining, this method has low machining efficiency, especially for the initial machining of solid blanks, where a lot of time is spent on the process of penetrating the flow channel. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a method and system for optimizing the feed path and tool electrode design in EDM roughing of curved and twisted flow channels. By combining optimization algorithms and secondary development technology of 3D model software, the optimal electrode feed direction and electrode shape are determined, simplifying the feed path and adopting a single linear feed. This simplifies the electrode design work for EDM roughing of curved and twisted flow channels of closed integral bladed disks, thereby improving roughing efficiency.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] An optimization method for feed path and tool electrode design in EDM roughing of curved and twisted flow channels is proposed. Roughing is performed using a single linear feed. The process for obtaining the feed path and electrode shape is as follows:

[0008] Step 1: Extract the flow channel model of the closed integral bladed disk in 3D modeling software;

[0009] Step 2: Select the tool electrode feed reference path to determine the search range for optimizing the feed direction;

[0010] Step 3: Randomly generate multiple feed directions within the search range, define each feed direction as a particle, and initialize the particle swarm;

[0011] Step 4: Calculate the workpiece flow channel allowance removed in different feed directions, and use it as the fitness function of the particle swarm optimization algorithm;

[0012] Step 5: Based on the fitness function, the feed direction of the tool electrode is iteratively updated using the particle swarm optimization algorithm in the 3D model software to obtain the optimal feed path of the tool electrode;

[0013] Step 6: Generate an initial tool electrode based on the optimal feed path of the tool electrode and gradually correct it to obtain the shape of the EDM roughing tool electrode for the closed integral bladed disk curved flow channel.

[0014] To optimize the above technical solution, the specific measures also include:

[0015] In step one, the flow channel model is a single flow channel extraction surface of a closed integral bladed disk, wherein the flow channel boundaries are defined by the profiles of two adjacent blades, the crown profile, and the hub profile, and the flow channel inlet section and the flow channel outlet section are determined.

[0016] In step two, the tool electrode feed reference path includes a reference point and a reference vector. The reference point is selected near the center of the flow channel inlet section. A straight line is created at the reference point with an angle θ to the reference vector. This straight line is used as the generatrix, and the reference vector is used as the rotation axis to form a conical range. The feed direction is optimized within this conical range, where θ ranges from 45° to 90°.

[0017] In step five, the optimal feed path of the tool electrode is obtained based on the feed direction and reference point obtained by removing the maximum amount of workpiece flow channel allowance or reaching the maximum number of iterations.

[0018] In step four, the calculation of the removed workpiece flow channel allowance adopts an integral approximation method. The specific process is as follows:

[0019] S41: Generate a set of lines within the flow channel inlet section with the current feed direction, adjacent line spacing of b, and filling the flow channel inlet section;

[0020] S42: Starting from the intersection of the set of straight lines and the inlet section of the flow channel, and ending at the intersection of the set of straight lines and the boundary and outlet sections of the flow channel, the straight lines are cut into line segments; these line segments are all inside the flow channel model, forming a cuboid that can be regarded as having a length and width of spacing b and a height of the line segment length.

[0021] S43: Calculate the total length L of the line segment set, and calculate the workpiece flow channel allowance V that can be removed in the current feed direction. The calculation formula is:

[0022] V = b 2 L.

[0023] Furthermore, the size of the spacing b in step S41 is specified according to the required accuracy of the solution for the removed workpiece flow channel allowance; the smaller the spacing, the higher the calculation accuracy.

[0024] In step six, the process of generating the tool electrode is as follows:

[0025] S61: Create a model in 3D modeling software with the same shape as the workpiece flow channel model, as the tool electrode blank;

[0026] S62: The tool electrode blank is retracted in the opposite direction of the optimal feed path in the workpiece flow channel model, and the part that interferes with the workpiece flow channel model is gradually removed until the tool electrode blank completely exits the workpiece flow channel model. The remaining part of the tool electrode blank is the initial tool electrode for the EDM roughing of the integral bladed disk bending flow channel.

[0027] S63: The initial tool electrode is reduced according to the discharge gap during machining and the machining allowance for subsequent finishing to obtain the final tool electrode shape.

[0028] Furthermore, during the operation in step S62, the design accuracy of the tool electrode is improved by reducing the length of the single retraction distance.

[0029] Furthermore, step S63 reduces the initial tool electrode according to the discharge gap during machining in order to leave a discharge gap between the workpiece and the tool electrode. The reduction position and reduction amount are determined according to the required discharge gap. The initial tool electrode is reduced according to the machining allowance of subsequent finishing to avoid overcutting during finishing after roughing. The reduction position and reduction amount are determined according to the machining allowance of finishing.

[0030] This invention also provides a system for optimizing the feed direction and electrode design in EDM roughing of curved and twisted flow channels, comprising:

[0031] The flow channel model extraction module is used to extract the flow channel model of a closed integral bladed disk.

[0032] The search range determination module determines the search range for optimizing the feed direction by selecting the tool electrode feed reference path.

[0033] The feed direction optimization module randomly generates multiple feed directions within the search range, defines each feed direction as a particle, and initializes the particle swarm; it calculates the workpiece flow channel allowance removed by different feed directions as the fitness function of the particle swarm optimization algorithm; based on the fitness function, it iteratively updates the feed direction of the tool electrode using the particle swarm optimization algorithm to obtain the optimal feed path of the tool electrode.

[0034] The electrode shape optimization module generates an initial tool electrode based on the optimal feed path of the tool electrode and gradually corrects it to obtain the shape of the tool electrode for EDM roughing of the closed integral bladed disk curved flow channel.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] The proposed method for optimizing the feed path and tool electrode design in EDM roughing of curved and twisted flow channels replaces complex spatial feed paths with straight feeds, significantly simplifying the design of feed paths and electrode shapes for EDM roughing of curved and twisted flow channels. Furthermore, it incorporates particle swarm optimization algorithms for optimization in 3D modeling software, resulting in a straight feed path and electrode shape that maximizes the removal of workpiece flow channel allowance. This method achieves large-scale roughing removal while reducing machining time, and is of great significance for improving the EDM efficiency of closed integral bladed disk parts with curved and twisted flow channel characteristics. Attached Figure Description

[0037] Figure 1 This is the main flowchart of the method for optimizing the feed path and tool electrode design of the curved and twisted flow channel EDM roughing in this invention;

[0038] Figure 2 This is a schematic diagram for calculating the amount of workpiece flow channel allowance after removal;

[0039] Figure 3 This is a schematic diagram of the electrode design for an EDM roughing tool for a closed-loop curved and twisted integral bladed disk. Detailed Implementation

[0040] The present invention will be further described in detail below through 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.

[0041] In one embodiment, the present invention proposes a method for optimizing the feed path and tool electrode design in curved and twisted flow channel EDM roughing, replacing complex spatial feed paths with linear feed, such as... Figure 1 As shown, obtaining the feed path and electrode shape includes the following steps:

[0042] Step 1: Extract the flow channel model of the closed integral bladed disk in 3D modeling software;

[0043] In the embodiment, the flow channel model is a flow channel of a single bladed disk in a closed integral bladed disk. The curved surfaces or plates that fit the adjacent two blades and the blade crown and hub shape are the flow channel boundaries. The flow channel inlet and flow channel outlet are respectively closed by curved surfaces or plates and defined as the flow channel inlet section and flow channel outlet section.

[0044] Step 2: Select the tool electrode feed reference path to determine the search range for optimizing the feed direction;

[0045] The tool electrode feed reference path includes a reference point and a reference direction. The reference point is selected near the center of the flow channel inlet section (the center of the section or a point close to the center of the section is used as the reference point). A straight line is created at the reference point with an angle θ to the reference vector. This straight line is used as the generatrix, and the reference vector is used as the axis of rotation to form a conical range. The search range of the feed direction is within the conical range where the angle between the generatrix and the direction of the reference vector is θ, where the value of θ ranges from 45° to 90°.

[0046] Step 3: Randomly generate multiple feed directions within the search range, define each feed direction as a particle, and initialize the particle swarm;

[0047] Step 4: Calculate the workpiece flow channel allowance removed in different feed directions and use it as the fitness function of the particle swarm optimization algorithm;

[0048] The calculation of the removed workpiece flow channel allowance is performed using an integral approximation method, such as... Figure 2 As shown, the specific process is as follows:

[0049] S41. Generate a set of lines within the flow channel inlet section with the current feed direction and an adjacent line spacing of b, filling the flow channel inlet section. The spacing b can be specified according to the required solution accuracy. The smaller the spacing, the higher the calculation accuracy of removing the allowance.

[0050] S42. Starting from the intersection of the set of straight lines with the inlet section of the flow channel, and ending at the intersection of the set of straight lines with the boundary of the flow channel and the inlet section of the flow channel, cut the straight lines into line segments. These line segments are all inside the flow channel model, forming a cuboid that can be regarded as having a length and width of spacing b and a height equal to the length of the line segment.

[0051] S43. Calculate the total length L of the line segment set, then the workpiece allowance V that can be removed in the current feed direction can be approximately calculated. The formula is:

[0052] V = b 2 L

[0053] Step 5: Based on the fitness function, the tool electrode feed direction is iteratively updated in the 3D model software using the particle swarm optimization algorithm until the workpiece flow channel removal margin is maximized or the maximum number of iterations is reached, thus obtaining the optimal feed path of the tool electrode.

[0054] The particle swarm optimization algorithm is executed in 3D modeling software.

[0055] Step Six: Generate an initial tool electrode based on the optimal feed path of the tool electrode and gradually refine it to obtain the shape of the EDM roughing electrode for the closed integral bladed disk curved flow channel, such as... Figure 3 As shown.

[0056] The process of generating the tool electrode is as follows:

[0057] S61. Create a model in 3D modeling software with the same shape as the workpiece flow channel model, as the tool electrode blank.

[0058] S62. The tool electrode blank is retracted in the workpiece flow channel model along the reverse of the optimal feed path, gradually removing the part that interferes with the workpiece flow channel model, until the tool electrode blank is completely removed from the workpiece flow channel model. The remaining part of the tool electrode blank is the initial tool electrode for EDM rough machining of the integral bladed disk twisted flow channel. During the operation, the design accuracy of the tool electrode can be improved by reducing the single retraction distance.

[0059] S63. The initial tool electrode is reduced according to the discharge gap during machining and the machining allowance for subsequent finishing to obtain the final roughing electrode shape.

[0060] The initial tool electrode is reduced according to the discharge gap during machining to leave a discharge gap between the workpiece and the tool electrode. The reduction position and amount are determined according to the required discharge gap. The initial tool electrode is reduced according to the machining allowance of subsequent finishing to avoid overcutting during finishing after roughing. The reduction position and amount are determined according to the machining allowance of finishing.

[0061] In another embodiment, the present invention proposes a feed direction and electrode design optimization system for curved and twisted flow channel EDM roughing, comprising:

[0062] The flow channel model extraction module is used to extract the flow channel model of a closed integral bladed disk.

[0063] The search range determination module determines the search range for optimizing the feed direction by selecting the tool electrode feed reference path.

[0064] The feed direction optimization module randomly generates multiple feed directions within the search range, defines each feed direction as a particle, and initializes the particle swarm; it calculates the workpiece flow channel allowance removed by different feed directions as the fitness function of the particle swarm optimization algorithm; based on the fitness function, it iteratively updates the feed direction of the tool electrode using the particle swarm optimization algorithm to obtain the optimal feed path of the tool electrode.

[0065] The electrode shape optimization module generates an initial tool electrode based on the optimal feed path of the tool electrode and gradually corrects it to obtain the shape of the tool electrode for EDM roughing of the closed integral bladed disk curved flow channel.

[0066] The above are merely preferred embodiments of the present invention and are 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 present invention and based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for optimizing the feed path and tool electrode design in EDM roughing of curved and twisted flow channels, characterized in that: Roughing is performed using a single linear feed. The process for obtaining the feed path and electrode shape is as follows: Step 1: Extract the flow channel model of the closed integral bladed disk in 3D modeling software; Step 2: Select the tool electrode feed reference path to determine the search range for optimizing the feed direction; Step 3: Randomly generate multiple feed directions within the search range, define each feed direction as a particle, and initialize the particle swarm; Step 4: Calculate the workpiece flow channel allowance removed in different feed directions, and use it as the fitness function of the particle swarm optimization algorithm; Step 5: Based on the fitness function, the feed direction of the tool electrode is iteratively updated using the particle swarm optimization algorithm in the 3D model software to obtain the optimal feed path of the tool electrode; Step 6: Generate an initial tool electrode based on the optimal feed path of the tool electrode and gradually correct it to obtain the shape of the EDM roughing tool electrode for the closed integral bladed disk curved flow channel. In step one, the flow channel model is a single flow channel extraction surface of a closed integral bladed disk, wherein the flow channel boundaries are defined by the profiles of two adjacent blades, the crown profile, and the hub profile, and the flow channel inlet section and the flow channel outlet section are determined. In step four, the calculation of the removed workpiece flow channel allowance adopts an integral approximation method. The specific process is as follows: S41: Generate a set of lines within the flow channel inlet section with the current feed direction, an adjacent line spacing of b, and filling the flow channel inlet section; S42: Starting from the intersection of the set of straight lines and the inlet section of the flow channel, and ending at the intersection of the set of straight lines and the boundary and outlet sections of the flow channel, cut the straight lines into line segments. These line segments are all inside the flow channel model, forming a cuboid that can be regarded as having a length and width of the spacing b and a height equal to the length of the line segment; S43: Calculate the total length L of the line segment set, and calculate the workpiece flow channel allowance V that can be removed in the current feed direction. The calculation formula is: 。 2. The method for optimizing the feed path and tool electrode design of curved and twisted flow channel EDM roughing according to claim 1, characterized in that: In step two, the tool electrode feed reference path includes a reference point and a reference vector. The reference point is selected near the center of the flow channel inlet section. A straight line is created at the reference point with an angle θ to the reference vector. This straight line is used as the generatrix, and the reference vector is used as the rotation axis to form a conical range. The feed direction is optimized within this conical range, where θ ranges from 45° to 90°.

3. The method for optimizing the feed path and tool electrode design in curved and twisted flow channel EDM roughing according to claim 1, characterized in that: In step five, the optimal feed path of the tool electrode is obtained based on the feed direction and reference point obtained by removing the maximum amount of workpiece flow channel allowance or reaching the maximum number of iterations.

4. The method for optimizing the feed path and tool electrode design in curved and twisted flow channel EDM roughing according to claim 1, characterized in that: The size of the spacing b in step S41 is specified according to the required accuracy of the solution for the removed workpiece flow channel allowance. The smaller the spacing, the higher the calculation accuracy.

5. The method for optimizing the feed path and tool electrode design of curved and twisted flow channel EDM roughing according to claim 1, characterized in that: In step six, the process of generating the tool electrode is as follows: S61: Create a model in 3D modeling software with the same shape as the workpiece flow channel model, as the tool electrode blank; S62: The tool electrode blank is retracted in the opposite direction of the optimal feed path in the workpiece flow channel model, and the part that interferes with the workpiece flow channel model is gradually removed until the tool electrode blank completely exits the workpiece flow channel model. The remaining part of the tool electrode blank is the initial tool electrode for the EDM roughing of the integral bladed disk bending flow channel. S63: The initial tool electrode is reduced according to the discharge gap during machining and the machining allowance for subsequent finishing to obtain the final tool electrode shape.

6. The method for optimizing the feed path and tool electrode design in curved and twisted flow channel EDM roughing according to claim 5, characterized in that: During the operation in step S62, the design accuracy of the tool electrode is improved by reducing the length of the single retraction distance.

7. The method for optimizing the feed path and tool electrode design of curved and twisted flow channel EDM roughing according to claim 5, characterized in that: Step S63 reduces the initial tool electrode according to the discharge gap during machining to leave a discharge gap between the workpiece and the tool electrode. The reduction position and amount are determined according to the required discharge gap. The initial tool electrode is reduced according to the machining allowance of subsequent finishing to avoid overcutting during finishing after roughing. The reduction position and amount are determined according to the machining allowance of finishing.

8. A system for optimizing the feed direction and electrode design in curved and twisted flow channel electrical discharge machining, employing the method for optimizing the feed path and tool electrode design in curved and twisted flow channel electrical discharge machining as described in any one of claims 1 to 7, characterized in that, include: The flow channel model extraction module is used to extract the flow channel model of a closed integral bladed disk. The search range determination module determines the search range for optimizing the feed direction by selecting the tool electrode feed reference path; The feed direction optimization module randomly generates multiple feed directions within the search range, defines each feed direction as a particle, and initializes the particle swarm; it calculates the workpiece flow channel allowance removed by different feed directions as the fitness function of the particle swarm optimization algorithm; based on the fitness function, it iteratively updates the feed direction of the tool electrode using the particle swarm optimization algorithm to obtain the optimal feed path of the tool electrode. The electrode shape optimization module generates an initial tool electrode based on the optimal feed path of the tool electrode and gradually corrects it to obtain the shape of the tool electrode for EDM roughing of the closed integral bladed disk curved flow channel.

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