Processing method for an electro discharge machining machine
By generating pre-EDM part and electrode models and performing Boolean operations using CAD tools, the problem that existing cavity models cannot accurately reflect the real cavity shape was solved, achieving high accuracy of the cavity model, optimizing machining parameters, and improving part machining quality and production efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GF MACHINING SOLUTIONS SA
- Filing Date
- 2021-11-26
- Publication Date
- 2026-06-02
AI Technical Summary
Existing technologies struggle to generate effective models for electrical discharge machining (EDM) machines. This inability to generate cavity models accurately reflects the true shape of the cavity, leading to suboptimal EDM operations and inaccurate final part production.
By generating pre-EDM part models and electrode models, Boolean operations are performed using computer-aided design (CAD) tools to generate highly accurate cavity models, which are then exported to different file formats to meet the needs of different machine manufacturers, including Step, Parasolid, Native SolidWorks format, IGES, etc.
It achieves accurate generation of cavity models, optimizes machining parameters, improves the quality and production efficiency of part machining, reduces electrode wear and production costs, and ensures the high precision of the final parts.
Smart Images
Figure CN114559114B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for generating a cavity model, specifically a cavity model in a format applicable to computer-aided design for electrical discharge machining. Background Technology
[0002] Electrical discharge machining (EDM) is a well-known process that uses a tool electrode to machine complex shapes onto a workpiece to obtain a final part with a designed shape. The original part is mounted on the machining table of a machine tool, and the tool electrode is mounted above the original part at a defined distance from the workpiece. The goal of the EDM process is to remove the material present on the part to achieve the final geometry of the final part. To achieve this, the electrode moves along a specific trajectory, and a voltage is applied between the electrode and the part. Along the entire trajectory, the voltage generates a discharge, which removes material from the part to obtain the desired final surface finish and final part shape.
[0003] A crucial parameter in preparing an EDM machining job is the geometric description of the cavity shape to be machined, which is defined as the so-called cavity model. Typically, a cavity model defining the geometry of the cavity is generated during the initial stage of EDM job creation. If the cavity model does not correspond to the actual cavity shape, the EDM job is not optimized and cannot produce the final part efficiently and accurately.
[0004] Furthermore, the choice of processing parameters depends on the cavity model, as the cavity model defines the volume of material to be etched by the EDM machine.
[0005] Currently, modeling the cavity shape to generate a cavity model is based on the shape of the electrode, for example, from a generated electrode model, or the designer must create it manually, which can be a time-consuming task depending on the complexity of the cavity to be machined. If an electrode model is used, the cavity shape is viewed as a 3D model of the electrode cut upwards from the bottom at a given height (such as a machining depth limit). In some cases, the cavity model based on the electrode model and the machining depth often does not correspond to the true shape of the cavity. For these common cases, designers are forced to use more complex modeling methods to properly define the cavity model. Summary of the Invention
[0006] The objective of this invention is to provide a method for generating cavity models for use in electrical discharge machining (EDM), wherein the cavity model needs to accurately reflect the shape of the cavity to be etched. Furthermore, the objective of this invention is to provide a method for automatically generating cavity models.
[0007] According to the invention, these objectives are achieved by the method for generating a cavity model, the method for machining parts using an electrode electrical discharge machining (EDM) machine tool, and the EDM machine. Furthermore, further advantageous embodiments are derived from the specification.
[0008] In this invention, a method for generating a cavity model for a workpiece machined by an electrical discharge machining (EDM) machine using tool electrodes includes: generating a pre-EDM part model and an electrode model; and calculating a cavity model that defines the geometry of the cavity based on the pre-EDM part model and the electrode model.
[0009] The pre-EDM part model defines the geometry of the part to be etched by the EDM machine to obtain the final part. The part can be a pre-machined part or a raw part, and its geometry is defined by the pre-EDM part model. The electrode model defines the geometry of the electrodes applied to the etched part. The cavity model defines the volume of the material to be etched and the geometry of the material to be removed by the EDM process.
[0010] Electrode models representing the geometry of the tool electrodes can be generated, for example, using computer-aided design (CAD) programs or imported into CAD tools. Specifically, the cavity model is calculated by performing Boolean calculations between the electrode model and the pre-EDM part model. The pre-EDM part model is a CAD model or a model in other formats. Preferably, the electrode model is a CAD model. Because calculation capabilities are provided in most tools (specifically CAD tools), the cavity model can be exported in a simple manner.
[0011] To meet the needs of different machine manufacturers, cavity model data can be exported to different file formats, such as Step, Parasolid, Native SolidWorks, and IGES.
[0012] In the preferred variant, the EDM pre-part is the original part, which is not processed through a manufacturing process, and the corresponding EDM pre-part model is the original part model.
[0013] In another preferred variant, the pre-EDM part is an intermediate part, which is pre-machined, and the corresponding pre-EDM part model is an intermediate part model. Pre-machining can be milling, EDM, laser machining, or any other machining type. For example, most of the cavity material is removed by milling, although the final cavity cannot be obtained by milling due to cavity details, aspect ratio, excessive wear of the cutting tool, and other reasons. The intermediate part model defines the geometry of the pre-machined part, i.e., the intermediate part. The intermediate part model can be obtained directly from CAD tools and / or from simulation tools. Advantageously, the intermediate part model is extracted from computer-aided manufacturing tools (CAM), such as from a 3D mesh model extracted from a milling operation simulation. CAM, for example, exports an STL file, which can be imported into CAD tools such as SolidWorks. The STL file can be automatically converted into a file that can be used for calculations. For example, the STL file can be converted into a mesh file.
[0014] In some embodiments, intermediate parts are obtained by etching a raw part using an EDM machine. Specifically, the raw part is first etched by a first electrode to obtain an intermediate part, and the intermediate part is further etched by one or more additional electrodes. In this variation, the EDM process should join different electrodes one after another to progressively obtain the final geometry. In this case, the method needs to take into account the machining sequence to define the correct cavity model for each specific electrode. We refer to the machining sequence as the order in which electrodes are joined from the first electrode used to the last electrode. Corresponding to each specific possible sequence, the method defines a specific cavity CAD model for each specific electrode.
[0015] In a variant, the method includes: generating a first EDM pre-part model defining the geometry of the original part to be etched by an EDM machine to obtain an intermediate part; generating a first electrode model defining the geometry of a first electrode applied to the etched original part; and calculating a first cavity model based on the first EDM pre-part model and the first electrode model, defining the geometry of the material to be removed from the original part by the first electrode to obtain the intermediate part. Furthermore, the method includes: generating a second EDM pre-part model defining the geometry of the intermediate part; generating a second electrode model defining the geometry of a second electrode applied to the etched intermediate part; and calculating a second cavity model defining the geometry of the material removed from the intermediate part by etching using the second electrode.
[0016] The first cavity model is calculated using a first electrode model and a first EDM pre-part model describing the geometry of the original part to be etched by the first electrode. Then, a second EDM pre-part model is generated by performing Boolean calculations between the first cavity model and the first EDM pre-part model.
[0017] In the second step, Boolean calculations are performed between the second EDM pre-part model and the second electrode model to obtain the second cavity model.
[0018] In this invention, a method for machining parts using an EDM machine tool includes the following steps: receiving a generated cavity model; determining machining parameters based on the cavity model; and machining the part using the received cavity model and the determined machining parameters.
[0019] In this invention, the electrical discharge machining (EDM) machine includes a machining stage on which a part is mounted, a tool holder for holding an electrode applied to the part, and a controller configured to receive the generated cavity model. Alternatively, the electrode model and the pre-EDM part model may be directly input into the controller, and the cavity model may also be calculated via the controller.
[0020] Preferably, the controller is further configured to determine multiple machining parameters based on the received cavity model. Because the cavity model generated using the method of the present invention provides high accuracy, the machining parameters calculated based on the accurate cavity model are optimized. This results in improved quality of the machined parts and increased production efficiency. Attached Figure Description
[0021] To describe how the advantages and features of the invention are obtained, a more specific description of the principles briefly described above will be presented below with reference to specific embodiments shown in the accompanying drawings. These drawings are merely illustrative of embodiments of the present disclosure and are therefore not to be construed as limiting its scope. The principles of the present disclosure are described and explained with additional features and details using the drawings, in which:
[0022] Figure 1 A comparison between the prior art and the present invention is shown;
[0023] Figure 2a Existing technology is shown;
[0024] Figure 2b An example of the invention is shown; and
[0025] Figure 3 Another example of the invention is shown. Detailed Implementation
[0026] Figure 1A comparison is shown between the models used in the prior art and those used in this invention. The workpiece model 21 is a model of the final part. If the part is pre-machined, this model does not include all geometric deviations due to limited machining accuracy. For example, corners 211 are modeled as perfect rectangles. In reality, such perfect rectangles cannot be achieved, for example, if the part is pre-machined by a milling process, as the diameter of the cutting tool will cause rounding at the corners. If this model is combined with the electrode model 10 to calculate the cavity model, errors in the corners will appear in the cavity model and thus lead to an incorrect interpretation of the cavity shape. Consequently, this will result in unoptimized EDM operations and inefficient and inaccurate production of the final part.
[0027] Conversely, the pre-EDM part model 23 is derived from actual machining, such as from a CAM system. Therefore, the generated model takes into account all geometric deviations caused by machining inaccuracies, such as corners 231. If this model is combined with the electrode model 10 to calculate the cavity model 28, rounded corners will appear in the cavity model, thus improving the accuracy of the final part machined by EDM based on the cavity model. Toolpaths and material removal are typically simulated for the milling process; therefore, this information can be directly input from the simulation tool of the milling process into the process of generating the cavity model. A 3D mesh model of the pre-machined workpiece can be extracted from the CAM system after the milling operation simulation and used as the pre-EDM part model. The cavity model is calculated by combining the electrode model and the pre-EDM part model. Boolean operations can be performed to calculate the cavity model based on the pre-EDM part model and the electrode model.
[0028] Figure 2a and Figure 2b An example is shown where a portion of the electrode shape is joined during processing. (e.g.) Figure 2b As shown, the left portion 10a of the electrode should not engage with the workpiece during EDM processing. If the cavity model is generated solely based on the electrode model, the cavity model will include, as shown... Figure 2aThe left portion shown does not correspond to the actual cavity shape. When selecting machining parameters based on this inaccurate cavity model, inappropriate machining parameters will be chosen. The calculated power setting will be unnecessarily high for machining the cavity, thus increasing electrode wear. This can lead to poor final part accuracy. If multiple cavities with the same shape must be machined, one electrode is typically used to machine multiple shapes. However, due to increased electrode wear, the electrode must be replaced earlier, increasing the number of electrodes required and thus increasing production costs. Furthermore, machining time will increase due to electrode wear and the additional material left by the roughing operation, which needs to be removed by the finishing pass. Because the power setting for the finishing pass is low, removing this additional material will significantly increase machining time. If an EDM pre-part model is used, then... Figure 2b The generated cavity model shown conforms to the actual geometry of the cavity, thus overcoming defects.
[0029] Figure 3 A further example is shown where a final part is obtained by machining a workpiece using different electrodes. EDM machining comprises two operations. In a first operation, a first electrode is mounted on a machine to etch the original workpiece to produce an intermediate part. In a second operation, a second electrode is mounted on a machine to etch the intermediate part to obtain the final part. To prepare for the first EDM operation, a model of the original part is provided as a first EDM pre-part model 33, and a model of the first electrode 31 is provided; Boolean operations are performed to calculate a first cavity model 36. To prepare for the second EDM operation, a model of the intermediate part is provided as a second EDM pre-part model 34, and a model of the second electrode 35 is provided; Boolean operations are performed to calculate a second cavity model 37. The second EDM pre-part model is an intermediate part model, which in this embodiment is obtained by applying the first EDM pre-part model and the first electrode model, specifically by performing Boolean calculations between them.
[0030] List of reference numerals in the attached diagram:
[0031] 10 Electrode Model
[0032] 21. Workpiece Model
[0033] 211 Corners of the workpiece model
[0034] 23 Pre-EDM part models
[0035] 231 Corner of the pre-EDM part model
[0036] 28 Cavity Model
[0037] 31 First Electrode
[0038] 33 First EDM Pre-part Model
[0039] 34 Second EDM Pre-part Model
[0040] 36 First cavity model
[0041] 37. Second cavity model.
Claims
1. A method for generating a cavity model, the cavity model being applied to a part machined using an electrode electrical discharge machining (EDM) machine with a tool electrode, the method comprising: a. Generate a part model before the electrode electrical discharge machining (EDM) machine, the part model defining the geometry of the part to be etched by the EDM machine to obtain the final part, wherein material removal by the pre-processing process is simulated, and a three-dimensional mesh model of the pre-processed workpiece is extracted from a computer-aided manufacturing system for use as the part model before the EDM machine. b. Generate an electrode model that defines the geometry of the tool electrode used to etch the part; as well as c. A cavity model is determined based on the generated part model before the electrode EDM machine and the generated electrode model, defining the geometry of the cavity, the cavity model representing the volume of material to be etched by the tool electrode.
2. The method according to claim 1, wherein the part model before the electrode electrical discharge machining is a computer-aided design model.
3. The method according to claim 1 or 2, wherein the part model before the electrode EDM machine and the electrode model are input into a computer-aided design tool, specifically the cavity model is calculated by performing Boolean calculations between the part model before the electrode EDM machine and the electrode model.
4. The method according to claim 1 or 2, wherein the part model before the electrode electrical discharge machining (EDM) machine defines the geometry of the original part.
5. The method of claim 4, wherein the part model before the electrode electrical discharge machining (EDM) machine defines the geometry of the intermediate part obtained by machining the original part.
6. The method of claim 5, wherein the original part is processed by one of the following processes to produce the intermediate part: milling, electrical discharge machining, laser processing, cutting, and grinding.
7. The method of claim 5, wherein the method further comprises: a. Generate a part model before the first electrode electrical discharge machining (EDM) machine, which is defined to be etched by the EDM machine to obtain the geometry of the original part of the intermediate part; b. Generate a first electrode model, which defines the geometry of the first electrode applied to the etching of the original part; c. Calculate a first cavity model, which defines the volume of material to be removed from the original part to obtain the intermediate part; d. Generate a part model before the second electrode electrical discharge machining, which defines the geometry of the intermediate part; e. Generate a second electrode model, which defines the geometry of the second electrode applied to the corrosion of the intermediate part; f. Calculate a second cavity model by performing Boolean operations between the part model before the second electrode electrical discharge machining and the second electrode model. The second cavity model defines the geometry of the material to be removed from the intermediate part by etching using the second electrode.
8. The method according to claim 1 or 2, wherein the part model before the electrode electrical discharge machining is extracted from a computer-aided manufacturing tool.
9. The method according to claim 1 or 2, wherein the electrode EDM front part model is extracted from the mesh file.
10. A method for machining parts using an electrode electrical discharge machining (EDM) machine tool, comprising: Receive the generated cavity model according to any one of claims 1 to 9; The processing parameters are determined based on the cavity model; as well as The part is machined using the received cavity model and the determined machining parameters.
11. An electrical discharge machining (EDM) machine, comprising a machining stage on which a part is mounted, a tool holder for holding an electrode applied to the machining part, and a controller configured to receive a cavity model generated by using the method according to any one of claims 1 to 9.
12. The electrical discharge machining machine of claim 11, wherein the controller is further configured to determine a plurality of machining parameters based on the received cavity model.