Design method of electric spark deep small hole machining process

Abstract

The invention discloses an electric spark deep small hole machining process design method, which belongs to the technical field of aero-engine part case machining, and comprises the following steps: designing an ultrasonic device to assist chip removal through ultrasonic vibration in the electric spark machining process, and adjusting the power of the ultrasonic device, the position of an ultrasonic vibration source and the angle of the ultrasonic vibration source; under different ultrasonic influence factors, carrying out orthogonal test electric spark machining on the deep small hole, wherein the ultrasonic influence factors comprise ultrasonic power, the distance between an ultrasonic vibration source and a machining part and the ultrasonic direction; the machining quality of the electric spark deep small hole machining test is compared, and the optimal ultrasonic influence factor combination is obtained; and the ultrasonic device is adjusted according to the optimal ultrasonic influence factor combination, and the adjusted ultrasonic device is used as an auxiliary device for electric spark deep small hole machining. The method has the advantage that carbon deposition in the electric spark deep small hole machining process is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of casing processing of aircraft engine parts, and in particular to a process design method for deep small hole processing using an electric spark. Background Art

[0002] In the field of aerospace, bearing seat parts are usually designed with oil injection holes. The main function of the hole is to spray lubricating oil to lubricate the bearing. Therefore, such small holes usually require the flow rate of lubricating oil. Some parts will produce carbon deposition after EDM to a certain depth due to the aperture ratio greater than 15. Carbon deposition is a local over-discharge caused by improper discharge conditions and poor chip removal during EDM, which forms obvious burn marks on the surface of the workpiece. In the process of deep hole EDM, carbon deposition is mainly caused by the inability to remove the chips removed during the machining process. Under the action of the internal flushing liquid, it is deposited at the bottom, resulting in carbon deposition caused by poor chip removal. Carbon deposition will cause the depth of small hole machining to "regress". Usually, after the carbon deposition phenomenon occurs, it needs to be removed manually, which is difficult to remove, resulting in low machining efficiency. After the carbon deposition phenomenon occurs, the aperture difference between the part orifice and the bottom of the hole can reach more than 0.04mm, resulting in instability or out-of-tolerance of the flow test data.

[0003] Electrospark small hole machining is a non-contact machining technology. During machining, pulse discharge is performed in the working fluid to remove the workpiece material. In theory, any conductive material can be machined and is not affected by the material properties. In addition, the chatter problem existing in traditional mechanical drilling can be reduced. The material removal rate of the EDM hole is low, and there is a molten solidification layer on the inner wall of the hole. With the increase of the hole making depth, the chip removal and deionization conditions gradually deteriorate, and abnormal discharge phenomena such as secondary discharge, arcing and short circuit tend to be serious, making it difficult to ensure the stability of small hole machining. With the increase of the hole making depth, the machining debris accumulates seriously, resulting in secondary discharge between the electrode and the inner wall of the hole, which leads to a tapered aperture, and the longer the machining time, the more obvious the taper phenomenon. Therefore, it is necessary to design an EDM deep small hole machining process to reduce the carbon deposition phenomenon. Summary of the invention

[0004] The invention provides a method for designing a process for machining deep small holes using electric sparks, so as to reduce carbon deposits during the machining process of deep small holes using electric sparks.

[0005] According to one aspect of the present invention, a method for designing a process for deep small hole machining by electrospark is provided, wherein an ultrasonic device is designed to assist chip removal by ultrasonic vibration during electrospark machining, and the power, ultrasonic vibration source position and ultrasonic vibration source angle of the ultrasonic device can be adjusted;

[0006] Orthogonal test of electrospark machining of deep small holes was carried out under different ultrasonic influencing factors, wherein the ultrasonic influencing factors include ultrasonic power, distance between ultrasonic vibration source and machining part, and ultrasonic direction;

[0007] Compare the machining quality of EDM deep small hole machining experiments and obtain the best combination of ultrasonic influencing factors;

[0008] The ultrasonic device is adjusted according to the optimal combination of ultrasonic influencing factors, and the adjusted ultrasonic device is used as an auxiliary device for electrospark deep small hole machining.

[0009] Optionally, the ultrasonic device includes a vibration source device for generating ultrasonic waves and a fixing fixture for supporting the vibration source device, and the fixing fixture includes a position adjustment component, an angle adjustment component and a clamping member.

[0010] Optionally, the position adjustment assembly includes vertical poles and horizontal poles which are perpendicular to each other, a base is fixed at the bottom of the vertical poles, an adapter sleeve is slidably provided on the vertical poles along the length direction, the horizontal poles are slidably matched with the adapter sleeves, and a locking bolt for locking the vertical poles and the horizontal poles is provided on the adapter sleeves.

[0011] Optionally, the clamping member includes two fixed plates fixed on the cross bar, the vibration source device is located between the two fixed plates and connected to the fixed plates, and the length of the fixed plates is not less than the maximum radius of the fan-shaped area swept by the vibration source device to avoid interference with the cross bar when the vibration source device rotates.

[0012] Optionally, two angle adjustment components are symmetrically arranged on both sides of the vibration source device, and each angle adjustment component includes a mounting block, a fixed block and a cover plate. One end of the mounting block is used to be fixedly connected to the vibration source device, and the other end of the mounting block is provided with a rotating shaft. The fixed block is arranged on the fixed plate, and the cover plate is fixed on the fixed block. A lower semicircular groove is formed on the fixed block, and an upper semicircular groove is formed on the cover plate. The upper semicircular groove and the lower semicircular groove are combined to form an axial hole for cooperating with the rotating shaft.

[0013] Optionally, one end of the rotating shaft of the mounting block extending out of the shaft hole is sleeved with a flat washer and threadedly connected with a butterfly nut.

[0014] Optionally, the vibration source device includes a shell and a vibrator unit disposed in the shell, the vibrator units are arranged in a matrix in the shell, and the vibrator units are connected in series.

[0015] Optionally, the comparison of the machining quality of the EDM deep small hole machining experiment includes performing a surface morphology analysis and a remelting layer thickness analysis on the machined surface.

[0016] Optionally, the ultrasonic wave direction includes horizontal, inclined at 45 degrees and vertical.

[0017] Optionally, the vibration source device adopts a total power of 1.8KW and a frequency of 40KHZ.

[0018] In summary, the present application includes at least one of the following beneficial technical effects:

[0019] 1. By setting up an ultrasonic device, ultrasonic vibration can be used to assist chip removal during EDM, which improves chip removal efficiency and solves the common chip removal problem in traditional EDM;

[0020] 2. This scheme uses orthogonal experiments to obtain the best combination of ultrasound influencing factors. By reasonably selecting experimental factors and levels, the multi-factor and multi-level experimental design is simplified to fewer experimental combinations, avoiding the requirement of a large number of experiments in full factorial experiments, saving time and resources;

[0021] 3. By setting the position adjustment component and the angle adjustment group, the position and angle of the vibration source device can be flexibly adjusted to facilitate experiments and improve the efficiency of obtaining the best combination of ultrasonic influencing factors.

[0022] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1 is a side view of the ultrasonic device of the present invention;

[0025] Figure 2 is a top view of the ultrasonic device of the present invention;

[0026] Figure 3 It is a structural schematic diagram of the vibration source device of the present invention;

[0027] Figure 4 Schematic diagram of ultrasound direction according to an embodiment of the present invention.

[0028] Legend:

[0029] 1. Base; 2. Vertical pole; 3. Adapter sleeve; 4. Fixing plate; 5. Mounting block; 6. Fixing block; 7. Cover plate; 8. Mounting block; 9. Cover plate; 10. Fixing block; 11. Flat washer; 12. Disc nut; 20. Cross bar; 30. Vibration source device. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0031] The following is combined with Figure 1-4 This application is described in further detail.

[0032] The embodiment of the present application discloses a method for designing a process for deep small hole machining using electric sparks.

[0033] A method for designing a process for machining deep small holes by electrosparking comprises the following steps: designing an ultrasonic device to assist chip removal by ultrasonic vibration during electrosparking machining, wherein the power, ultrasonic vibration source position and ultrasonic vibration source angle of the ultrasonic device are all adjustable; conducting orthogonal experiments on electrosparking machining deep small holes under different ultrasonic influencing factors, wherein the ultrasonic influencing factors include ultrasonic power, the distance between the ultrasonic vibration source and the machining part, and the ultrasonic direction; comparing the machining quality of the electrosparking machining experiments to obtain the best combination of ultrasonic influencing factors; adjusting the ultrasonic device according to the best combination of ultrasonic influencing factors, and using the adjusted ultrasonic device as an auxiliary device for electrosparking machining deep small holes.

[0034] By introducing ultrasonic vibration to assist chip removal, the chip removal efficiency can be significantly improved, solving the problem of difficult chip removal in traditional EDM. The vibration and cavitation effect of ultrasound help to remove the machining debris from the machining area, reducing the accumulation of debris and the resulting carbon deposition, thereby ensuring the stability of the machining process. Secondly, the orthogonal test method is used to find the best parameter combination with a small number of experiments by adjusting factors such as ultrasonic power, the distance between the vibration source and the machining part, and the ultrasonic direction. This optimization strategy avoids the large number of experiments required for full factor experiments, saves time and resources, and improves experimental efficiency. Furthermore, by adjusting the power, position and angle of the ultrasonic device, the process can flexibly adapt to the machining requirements of different workpieces, especially deep small hole machining with high precision requirements. The optimized combination of ultrasonic influencing factors makes the diameter difference between the hole mouth and the bottom of the hole smaller, and the machining quality is more consistent. In addition, ultrasonic assistance can also effectively reduce abnormal discharge phenomena such as secondary discharge, arcing and short circuit in EDM, making the machining process more stable, reducing machining defects, and at the same time extending the service life of the electrode and improving the surface quality of the workpiece. This process design not only significantly improves the material removal rate, but also greatly improves the processing efficiency, especially solves the rework problem caused by poor chip removal, and significantly improves the overall efficiency. In addition, the ultrasonic device has the adjustability of power, position and angle, which can meet the processing requirements of workpieces of different shapes, sizes and complexity, and is particularly suitable for occasions requiring high-precision deep small hole processing in fields such as aerospace.

[0035] Ultrasonic power directly affects the intensity of ultrasonic vibration and the chip removal effect. Higher power can enhance chip removal and improve the spark discharge environment in the processing area, improving processing efficiency and quality. Therefore, selecting power as a key factor can effectively optimize the chip removal process. Secondly, the distance between the ultrasonic vibration source and the processing area will affect the effect of ultrasonic vibration on the processing area. The appropriate distance can ensure that the ultrasonic vibration produces sufficient cavitation effect in the working fluid. Too close or too far will affect the chip removal efficiency and processing stability. Therefore, adjusting the distance is one of the keys to improving the process effect. Finally, the direction of the ultrasonic wave determines the angle of action of the ultrasonic vibration. Different directions will cause the ultrasonic wave to act on the processing area in different ways, which may affect the chip removal and the stability of the spark discharge. By optimizing the direction of the ultrasonic wave, better chip removal effect and stable processing environment can be achieved.

[0036] Reference Figure 1 , the ultrasonic device includes a vibration source device 30 for generating ultrasonic waves and a fixing fixture for supporting the vibration source device 30, and the fixing fixture includes a position adjustment component, an angle adjustment component and a clamp. The vibration source device 30 is used to generate ultrasonic waves, and its function is to generate cavitation effect in the working fluid through vibration, and assist chip removal and stability during the electrospark machining process. Therefore, it is the core component for realizing ultrasonic assisted machining. Secondly, the fixing fixture plays the role of supporting and stabilizing the vibration source device 30, ensuring that the vibration source device 30 vibrates effectively at a suitable working position and angle. The position adjustment component is used to adjust the distance between the vibration source device 30 and the machining part, which allows the operator to flexibly adjust the ultrasonic action distance according to the different needs of the workpiece, ensuring that the vibration works at the most effective position; the angle adjustment component is used to adjust the direction of the vibration source device 30, and different angle settings can ensure that the ultrasonic wave acts in different directions of the machining area, thereby optimizing the chip removal effect and machining quality; the clamp is responsible for fixing the vibration source device 30, ensuring the stability of the vibration source device 30 during the machining process, preventing loosening or displacement during the vibration process, and ensuring the continuity and accuracy of the machining process.

[0037] The position adjustment assembly includes a vertical pole 2 and a horizontal pole 20 which are perpendicular to each other. A base 1 is fixed to the bottom of the vertical pole 2. An adapter sleeve 3 is slidably provided on the vertical pole along the length direction. The horizontal pole 20 is slidably matched with the adapter sleeve 3. The adapter sleeve 3 is provided with a locking bolt for locking the vertical pole and the horizontal pole 20.

[0038] Reference Figure 1 and Figure 2, the clamping member includes two fixing plates 4 fixed on the cross bar 20, the vibration source device 30 is located between the two fixing plates 4 and connected to the fixing plates 4, and the length of the fixing plates 4 is not less than the maximum radius of the fan-shaped area swept by the vibration source device 30 to avoid interference with the cross bar 20 when the vibration source device 30 rotates. The setting of the fixing plates 4 provides a firm support and stability for the vibration source device 30, ensuring that the vibration source device 30 remains stable during the working process, avoiding displacement or loosening due to vibration, and ensuring the continuity and accuracy of ultrasonic machining. Secondly, the length of the fixing plates 4 is designed to be not less than the maximum radius of the fan-shaped area swept by the vibration source device 30, which ensures that when adjusting the angle of the vibration source device 30, the vibration source device 30 can rotate freely within the allowed range without interfering or colliding with the cross bar 20, so that the angle adjustment of the vibration source device 30 can be achieved without damaging the equipment or affecting the working accuracy.

[0039] Two angle adjustment components are symmetrically arranged on both sides of the vibration source device 30, and each angle adjustment component includes a mounting block 8, a fixing block 10 and a cover plate 9. One end of the mounting block 8 is used for fixed connection with the vibration source device 30, and the other end of the mounting block 8 is provided with a rotating shaft. The fixing block 10 is arranged on the fixing plate 4, and the cover plate 9 is fixed on the fixing block 10. A lower semicircular groove is formed on the fixing block 10, and an upper semicircular groove is formed on the cover plate 9. The upper semicircular groove and the lower semicircular groove are combined to form an axial hole for matching with the rotating shaft. The axial hole formed by the fixing block 10 and the cover plate 9 through the lower semicircular groove and the upper semicircular groove can accurately match with the rotating shaft. This design ensures that the rotating shaft is firmly fixed, while allowing it to rotate freely within a specific range, so that the vibration source device 30 can be adjusted to the best working angle as needed. In addition, the combination of the cover plate 9 and the fixing block 10 provides additional support and protection to ensure that the rotating shaft will not loosen due to vibration or impact during processing. The function of the overall design is to provide a flexible angle adjustment function so that the ultrasonic vibration source device 30 can be adjusted to a suitable angle according to different processing requirements and workpiece shapes.

[0040] Reference Figure 2, one end of the rotating shaft of the mounting block 8 extending out of the shaft hole is sleeved with a flat washer 11 and threadedly connected with a butterfly nut 12. When the rotating shaft passes through the shaft hole formed by the upper semicircular groove and the lower semicircular groove, it has the freedom of rotation, so that the vibration source device 30 can be adjusted to different angles according to processing requirements. A flat washer 11 is set at one end of the rotating shaft extending out of the shaft hole, and its function is to provide a smooth contact surface to prevent excessive friction or damage when the nut directly contacts the surface of the component. At the same time, the flat washer 11 can also evenly disperse the locking force of the nut to ensure uniform force during locking. Next, the locking effect is achieved by the threaded butterfly nut 12. The butterfly nut 12 is elastic, and its design can generate additional pre-tightening force after tightening. By pressing the flat washer 11 to fix the rotating shaft, the vibration source device 30 is firmly locked at the current angle position. Due to the elastic structure of the butterfly nut 12, after locking, it can provide continuous pressing force to avoid loosening due to vibration or other factors. In this way, when the butterfly nut 12 is tightened, the rotating shaft is locked, and the vibration source device 30 is fixed at the set angle and no longer rotates.

[0041] Reference Figure 3 The vibration source device 30 includes a shell and a vibrator unit arranged in the shell. The vibrator units are arranged in a matrix in the shell, and the vibrator units are connected in series. The matrix arrangement of the vibrator units provides a more uniform and powerful vibration effect. The matrix arrangement means that the vibrator units can work simultaneously at different positions, ensuring that the ultrasonic wave is evenly propagated in the working fluid, so that the entire processing area is subjected to continuous and consistent ultrasonic vibration. This evenly distributed vibration effect helps to improve chip removal and prevent debris from accumulating in the processing area, thereby improving the efficiency and quality of EDM. The design of series connection between the vibrator units helps to improve the overall vibration power and efficiency. The series structure allows each vibrator unit to work together, and the vibration energy is gradually transmitted and amplified, thereby enhancing the vibration intensity. This is particularly important for deep and small hole processing, because as the hole depth increases, the difficulty of chip removal and ionization increases. Stronger ultrasonic vibration can more effectively remove chips, improve the deionization conditions in EDM, and reduce abnormal discharge phenomena such as secondary discharge or short circuit.

[0042] Comparison of the machining quality of deep small hole EDM tests includes surface morphology analysis and remelting layer thickness analysis of the machined surface. Surface morphology analysis can directly reflect the surface finish, flatness and machining defects of the workpiece. By analyzing the surface, it can be determined whether common machining defects such as burns, cracks, pits, etc. have occurred during the machining process. These defects may be caused by poor discharge conditions, debris accumulation or carbon deposition. Surface morphology analysis can help evaluate whether ultrasonic-assisted EDM has significantly reduced these defects, thereby optimizing machining parameters. Remelting layer thickness analysis is crucial for evaluating the quality of EDM. The remelting layer is a layer formed by local melting and resolidification of the material during EDM. Excessive thickness will affect the mechanical properties of the workpiece, especially in the case of high precision and high strength requirements, such as parts in the aerospace field. By analyzing the thickness of the remelting layer, the influence of machining parameters on the surface quality can be judged. Ultrasonic-assisted technology helps to reduce secondary discharge and abnormal discharge, thereby effectively reducing the thickness of the remelting layer and improving the surface quality of the workpiece.

[0043] In a specific embodiment, the ultrasonic direction includes horizontal, inclined 45 degrees and vertical directions. The vibration source device adopts a total power of 1.8KW and a frequency of 40KHZ. Through the orthogonal test method, different ultrasonic auxiliary conditions are set, that is, the ultrasonic generator is located in the horizontal, inclined 45° and vertical directions of the part. Figure 4 As shown in the table below, the three most important factors in the ultrasonic EDM deep small hole machining process were tested to determine the optimal machining parameters. The specific parameters are shown in the table below.

[0044]

[0045] Through the research on ultrasonic EDM technology, the carbon deposition, chip removal difficulty and deionization phenomena in the EDM deep small hole machining process have been improved, the machining efficiency has been improved by 22.19%, the material removal rate has been increased from 1.2022mm3 / h to 1.544mm3 / h, and the diameter difference between the small hole mouth and the hole bottom is controlled at 0.02mm, and can actually reach 0.008mm.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. The process design method for deep small hole machining by electric spark is characterized by: The steps include: An ultrasonic device is designed to assist chip removal through ultrasonic vibration during EDM, and the power, ultrasonic vibration source position and ultrasonic vibration source angle of the ultrasonic device can be adjusted; Orthogonal test of electrospark machining of deep small holes was carried out under different ultrasonic influencing factors, wherein the ultrasonic influencing factors include ultrasonic power, distance between ultrasonic vibration source and machining part, and ultrasonic direction; Compare the machining quality of EDM deep small hole machining experiments and obtain the best combination of ultrasonic influencing factors; The ultrasonic device is adjusted according to the optimal combination of ultrasonic influencing factors, and the adjusted ultrasonic device is used as an auxiliary device for electrospark deep small hole machining.

2. The method for designing a process for deep small hole machining by electrospark according to claim 1, characterized in that: The ultrasonic device comprises a vibration source device (30) for generating ultrasonic waves and a fixing fixture for supporting the vibration source device (30), wherein the fixing fixture comprises a position adjustment component, an angle adjustment component and a clamping member.

3. The method for designing a deep small hole electrospark machining process according to claim 2, characterized in that: The position adjustment assembly comprises a vertical pole (2) and a horizontal pole (20) which are perpendicular to each other. A base (1) is fixed at the bottom of the vertical pole (2). An adapter sleeve (3) is slidably arranged on the vertical pole along the length direction. The horizontal pole (20) is slidably matched with the adapter sleeve (3). A locking bolt for locking the vertical pole and the horizontal pole (20) is arranged on the adapter sleeve (3).

4. The method for designing a process for deep small hole machining by electrospark according to claim 3, characterized in that: The clamping member comprises two fixing plates (4) fixed on the cross bar (20), the vibration source device (30) is located between the two fixing plates (4) and connected to the fixing plates (4), and the length of the fixing plates (4) is not less than the maximum radius of the fan-shaped area swept by the vibration source device (30) when rotating, so as to avoid interference between the vibration source device (30) and the cross bar (20) when rotating.

5. The method for designing a process for deep small hole machining by electrospark according to claim 4, characterized in that: Two angle adjustment components are symmetrically arranged on both sides of the vibration source device (30), and each angle adjustment component comprises a mounting block (8), a fixing block (10) and a cover plate (9); one end of the mounting block (8) is used for fixed connection with the vibration source device (30), and the other end of the mounting block (8) is provided with a rotating shaft; the fixing block (10) is arranged on the fixing plate (4); the cover plate (9) is fixed on the fixing block (10); a lower semicircular groove is formed on the fixing block (10), and an upper semicircular groove is formed on the cover plate (9); the upper semicircular groove and the lower semicircular groove are combined to form an axial hole for cooperating with the rotating shaft.

6. The method for designing a process for deep small hole machining by electrospark according to claim 5, characterized in that: One end of the rotating shaft of the mounting block (8) extending out of the shaft hole is sleeved with a flat washer (11) and is threadedly connected with a butterfly nut (12).

7. The method for designing a process for deep small hole machining by electrospark according to claim 6, characterized in that: The vibration source device (30) comprises a shell and a vibrator unit arranged in the shell, wherein the vibrator units are arranged in a matrix in the shell, and the vibrator units are connected in series.

8. The method for designing a process for deep small hole machining by electrospark according to claim 7, characterized in that: The machining quality of the comparative electric spark deep small hole machining test includes surface morphology analysis and remelting layer thickness analysis of the machined surface.

9. The method for designing a process for deep small hole machining by electrospark according to claim 1, characterized in that: The ultrasonic wave directions include horizontal, 45 degree inclined and vertical directions.

10. The process design method for deep small hole electrospark machining according to claim 2, characterized in that: The vibration source device (30) adopts a total power of 1.8KW and a frequency of 40KHZ.

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