Electrical discharge deep hole machining process design method

Abstract

The application discloses a kind of electric spark deep small hole machining process design methods, belong to the field of aero-engine parts casing processing technology, it includes design ultrasonic device, to in electric spark machining process through ultrasonic vibration auxiliary chip removal, the power of ultrasonic device, ultrasonic vibration source position and ultrasonic vibration source angle can be adjusted;Orthogonal test electric spark machining deep small hole is carried out under different ultrasonic influence factors, the ultrasonic influence factors include ultrasonic power, ultrasonic vibration source and processing site distance and ultrasonic direction;The processing quality of electric spark deep small hole machining test is compared, and the best ultrasonic influence factor combination is obtained;According to the best ultrasonic influence factor combination adjustment ultrasonic device, and using adjusted ultrasonic device as the auxiliary device of electric spark deep small hole machining.The present application has the advantage of reducing carbon deposition in the process of electric spark deep small hole machining.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of machining technology of aero-engine parts, in particular to an EDM deep small hole machining process design method. BACKGROUND

[0002] The bearing seat parts in the field of aerospace are usually designed with oil injection small holes. The main function of the hole is to inject lubricating oil to the bearing, so the small hole usually requires the flow of lubricating oil. Due to the hole diameter ratio greater than 15, carbon deposition phenomenon occurs after EDM to a certain depth. Carbon deposition is caused by local over-discharge due to improper selection of discharge conditions and poor chip removal during EDM. It forms obvious burn marks on the workpiece surface. In the process of EDM deep small hole machining, the carbon deposition is mainly caused by the accumulation of the removed chips in the bottom under the action of the internal flushing liquid, which leads to poor chip removal. Carbon deposition can cause the "retrogression" of the small hole machining depth. After the carbon deposition occurs, it is difficult to remove the carbon deposition by manual removal, which leads to low machining efficiency. In addition, the diameter difference between the hole orifice and the hole bottom can reach more than 0.04mm after the carbon deposition occurs, which leads to unstable or out-of-tolerance flow test data.

[0003] EDM small hole machining is a non-contact machining technology. During machining, pulse discharge is carried out in the working liquid to remove the workpiece material. In theory, it can machine any conductive material and is not affected by the material properties. In addition, it can also reduce the chatter problem existing in traditional mechanical drilling. EDM has a low material removal rate, and there is a molten solidification layer on the inner wall of the hole. As the hole depth increases, the chip removal and deionization conditions gradually deteriorate, and abnormal discharge phenomena such as secondary discharge, arc and short circuit tend to be more serious, making it difficult to ensure the stability of small hole machining. As the hole depth increases, the machining debris accumulation phenomenon is serious, which leads to secondary discharge between the electrode and the inner wall of the hole, resulting in hole diameter tapering. The longer the machining time, the more obvious the tapering phenomenon. Therefore, it is necessary to design an EDM deep small hole machining process to reduce the carbon deposition phenomenon. SUMMARY

[0004] The present application provides an EDM deep small hole machining process design method to reduce carbon deposition during EDM deep small hole machining.

[0005] According to one aspect of the present application, an EDM deep small hole machining process design method is provided, in which an ultrasonic device is designed to assist in chip removal during EDM by ultrasonic vibration. The power of the ultrasonic device, the position of the ultrasonic vibration source and the angle of the ultrasonic vibration source can be adjusted.

[0006] Orthogonal test is carried out on the EDM deep hole machining under different ultrasonic influencing factors, including ultrasonic power, distance between ultrasonic vibration source and machining position and ultrasonic direction.

[0007] The machining quality of the EDM deep hole machining experiment is compared to obtain the optimal ultrasonic influencing factor combination.

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

[0009] Optionally, the ultrasonic device comprises a vibration source device for generating ultrasonic waves and a fixing clamp for supporting the vibration source device, and the fixing clamp comprises a position adjusting assembly, an angle adjusting assembly and a clamping piece.

[0010] Optionally, the position adjusting assembly comprises a vertical rod and a horizontal rod which are perpendicular to each other, the bottom of the vertical rod is fixed with a base, an adapter sleeve is slidably arranged on the vertical rod along the length direction, the horizontal rod is in sliding fit with the adapter sleeve, and the adapter sleeve is provided with locking bolts for locking the vertical rod and the horizontal rod.

[0011] Optionally, the clamping piece comprises two fixed plates fixed on the horizontal rod, the vibration source device is located between the two fixed plates and connected with 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 in rotation, so as to avoid interference between the vibration source device and the horizontal rod in rotation.

[0012] Optionally, the angle adjusting assembly is symmetrically arranged on both sides of the vibration source device, and each angle adjusting assembly comprises a mounting block, a fixed block and a cover plate, one end of the mounting block is used for fixed connection with the vibration source device, the other end of the mounting block is provided with a rotating shaft, the fixed block is arranged on the fixed plate, the cover plate is fixed on the fixed block, a lower semicircular groove is formed in the fixed block, and an upper semicircular groove is formed in the cover plate, the upper semicircular groove and the lower semicircular groove are combined to form a shaft hole for cooperating with the rotating shaft.

[0013] Optionally, a flat washer is sleeved on the end of the rotating shaft of the mounting block which protrudes out of the shaft hole, and a disc nut is threadedly connected with the flat washer.

[0014] Optionally, the vibration source device comprises 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.

[0015] Optionally, the machining quality of the EDM deep hole machining experiment comprises surface morphology analysis and remelted layer thickness analysis on the machined surface.

[0016] Optionally, the ultrasonic direction comprises horizontal direction, 45-degree inclined direction and vertical direction.

[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 the ultrasonic device, the ultrasonic vibration can assist in chip removal during electric spark machining, the chip removal efficiency is improved, and the common chip removal difficulty problem in traditional electric spark machining is solved;

[0020] 2. The present scheme adopts orthogonal experiment to obtain the best ultrasonic influence factor combination, and simplifies the multi-factor and multi-level experiment design into fewer experimental combinations by reasonably selecting experimental factors and levels, avoiding the requirement of a large number of experimental times in full-factor experiment, and saving time and resources;

[0021] 3. The position adjusting assembly and the angle adjusting assembly can flexibly adjust the position and angle of the vibration source device, which is convenient for experiment and improves the efficiency of obtaining the best ultrasonic influence factor combination.

[0022] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which form a part of this application, are included to provide a further understanding of the application, illustrate the preferred embodiments of the application and assist in the explanation of the application. In the drawings:

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

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

[0026] Figure 3 is a structural schematic view of the vibration source device of the present application;

[0027] Figure 4 is a schematic view of the ultrasonic direction of the embodiment of the present application.

[0028] LEGEND:

[0029] 1, base; 2, vertical rod; 3, adapter sleeve; 4, fixed plate; 5, mounting block; 6, fixed block; 7, cover plate; 8, mounting block; 9, cover plate; 10, fixed block; 11, flat washer; 12, disc nut; 20, cross rod; 30, vibration source device. DETAILED DESCRIPTION

[0030] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following description.

[0031] The embodiments of the present application will be described in detail below with reference to the accompanying drawings, but the present application can be implemented in various different ways as defined and covered by the following description. Figures 1-4 The present application is further described in detail.

[0032] The embodiments of the present application disclose a deep small hole EDM process design method.

[0033] The deep small hole EDM process design method comprises the following steps: designing an ultrasonic device to assist in chip removal through ultrasonic vibration during EDM, the power of the ultrasonic device, the position of the ultrasonic vibration source and the angle of the ultrasonic vibration source can be adjusted; performing orthogonal test EDM deep small hole under different ultrasonic influencing factors, the ultrasonic influencing factors include ultrasonic power, distance between the ultrasonic vibration source and the machining part and ultrasonic direction; comparing the machining quality of the EDM deep small hole machining experiment to obtain the best ultrasonic influencing factor combination; adjusting the ultrasonic device according to the best ultrasonic influencing factor combination, and using the adjusted ultrasonic device as an auxiliary device for EDM deep small hole machining.

[0034] By introducing ultrasonic vibration to assist in chip removal, the chip removal efficiency can be significantly improved, and the problem of difficult chip removal in traditional EDM process is solved. The vibration and cavitation effect of ultrasonic waves help to remove machining chips from the machining area, reducing the accumulation of chips and the resulting phenomenon of carbon deposition, thereby ensuring the stability of the machining process. Secondly, by adjusting the ultrasonic power, the distance between the vibration source and the machining part and the ultrasonic direction, the best parameter combination is found in a small number of experiments through orthogonal test method. This optimization strategy avoids the large number of experiments required by full-factor experiments, saves time and resources, and improves experimental efficiency. Furthermore, by adjusting the power, position and angle of the ultrasonic device, this process can flexibly adapt to the machining requirements of different workpieces, especially deep small hole machining with high precision requirements. The optimized ultrasonic influencing factor combination makes the diameter difference between the hole mouth and the hole bottom smaller, and the machining quality more consistent. In addition, ultrasonic assistance can effectively reduce the abnormal discharge phenomena such as secondary discharge, arc and short circuit in EDM, making the machining process more stable, reducing machining defects, prolonging 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 machining efficiency, especially solves the rework problem caused by poor chip removal, and the overall efficiency is significantly improved. Moreover, the ultrasonic device has the adjustability of power, position and angle, which can meet the machining requirements of different shapes, sizes and complex workpieces, and is especially suitable for high-precision deep small hole machining in the fields of aerospace and other fields.

[0035] The ultrasonic power directly affects the intensity of ultrasonic vibration and the chip removal effect. Higher power can enhance chip removal and improve the electrical discharge environment in the machining area, thereby improving machining efficiency and quality. Therefore, selecting power as a key factor can effectively optimize the chip removal process. Second, the distance between the ultrasonic vibration source and the machining site affects the effect of ultrasonic vibration on the machining area. A suitable distance can ensure that ultrasonic vibration produces sufficient cavitation effect in the working fluid. Too close or too far will affect the chip removal efficiency and machining stability. Therefore, adjusting the distance is one of the keys to improving process effectiveness. Finally, the direction of ultrasonic waves determines the angle of ultrasonic vibration. Different directions will result in different ways of ultrasonic waves acting on the machining area, which may affect the stability of chip removal and electrical discharge. By optimizing the direction of ultrasonic waves, better chip removal effect and stable machining environment can be achieved.

[0036] Reference Figure 1 The ultrasonic device includes a vibration source device 30 for generating ultrasonic waves and a fixed clamp for supporting the vibration source device 30. The fixed clamp includes a position adjusting assembly, an angle adjusting assembly, and a clamping piece. The vibration source device 30 is used to generate ultrasonic waves, which acts to produce cavitation effect in the working fluid through vibration, assisting chip removal and stability during electrical discharge machining. Therefore, it is the core component of ultrasonic-assisted machining. Second, the fixed clamp plays a role in supporting and stabilizing the vibration source device 30, ensuring that the vibration source device 30 vibrates effectively at the right working position and angle. The position adjusting assembly is used to adjust the distance between the vibration source device 30 and the machining site, which allows the operator to flexibly adjust the action distance of ultrasonic waves according to the different needs of the workpiece, ensuring that the vibration works effectively at the most effective position. The angle adjusting assembly is used to adjust the direction of the vibration source device 30. Different angle settings can ensure that ultrasonic waves act in different directions on the machining area, thereby optimizing chip removal effect and machining quality. The clamping piece is responsible for fixing the vibration source device 30, ensuring the stability of the vibration source device 30 during machining, preventing loosening or displacement during vibration, and ensuring the continuity and accuracy of the machining process.

[0037] The position adjusting assembly includes a vertical rod 2 and a horizontal rod 20 perpendicular to each other. The bottom of the vertical rod 2 is fixed with a base 1. A conversion sleeve 3 is slidably arranged on the vertical rod along the length direction. The horizontal rod 20 is in sliding cooperation with the conversion sleeve 3. The conversion sleeve 3 is provided with locking bolts for locking the vertical rod and the horizontal rod 20.

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

[0039] The angle adjustment assembly is symmetrically arranged on both sides of the vibration source device 30, and each angle adjustment assembly includes a mounting block 8, a fixed block 10, and a cover plate 9. One end of the mounting block 8 is fixedly connected with the vibration source device 30, and the other end of the mounting block 8 is provided with a rotating shaft. The fixed block 10 is arranged on the fixed plate 4, and the cover plate 9 is fixed on the fixed block 10. The fixed block 10 is formed with a lower semicircular groove, and the cover plate 9 is formed with an upper semicircular groove. The upper semicircular groove and the lower semicircular groove are combined to form an axle hole for cooperating with the rotating shaft. The fixed block 10 and the cover plate 9 are combined to form an axle hole through the lower semicircular groove and the upper semicircular groove, which can accurately cooperate with the rotating shaft. This design not only ensures the firm fixation of the rotating shaft, but also allows it to rotate freely within a certain 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 fixed block 10 provides additional support and protection, ensuring that the rotating shaft will not loosen due to vibration or impact during processing. The overall design provides flexible angle adjustment function, so that the ultrasonic vibration source device 30 can be adjusted to the appropriate angle according to different processing needs and workpiece shapes.

[0040] Referring to Figure 2The end of the rotating shaft of the mounting block 8 extending out of the shaft hole is sleeved with a flat washer 11 and threaded with a disc 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, allowing the vibration source device 30 to be adjusted to different angles according to processing needs. The flat washer 11 is provided at the end of the rotating shaft extending out of the shaft hole, which provides a smooth contact surface to prevent excessive friction or damage when the nut directly contacts the surface of the assembly. At the same time, the flat washer 11 can also uniformly distribute the locking force of the nut to ensure even force during locking. Next, the locking effect is achieved through the threaded disc nut 12. The disc nut 12 has elasticity, which can generate additional pre-tightening force after tightening, fixing the rotating shaft by pressing the flat washer 11, thereby firmly locking the vibration source device 30 at the current angle position. Due to the elastic structure of the disc nut 12, it can provide continuous compression force after locking, avoiding loosening caused by vibration or other factors. In this way, when the disc 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] Referring to Figure 3 The vibration source device 30 includes a housing and a vibrator unit arranged in the housing. The vibrator units are arranged in a matrix in the housing and are connected in series. The matrix arrangement of the vibrator units provides more uniform and powerful vibration effects. The matrix arrangement means that the vibrator units can work simultaneously at different positions, ensuring that the ultrasonic waves are uniformly propagated in the working fluid, so that the entire processing area is subjected to consistent ultrasonic vibration effects. This uniform distribution of vibration effects helps to improve chip removal and prevent debris from accumulating in the processing area, thereby improving the efficiency and quality of electric discharge machining. The series connection design between the vibrator units helps to improve the overall vibration power and efficiency. The series structure allows each vibrator unit to work cooperatively, and the vibration energy is gradually transmitted and amplified, thereby enhancing the vibration intensity. This is particularly important for deep and small hole machining, as the difficulty of chip removal and ionization increases with the depth of the hole. Stronger ultrasonic vibration can more effectively remove chips and improve the deionization conditions in electric discharge machining, reducing abnormal discharge phenomena such as secondary discharge or short circuit.

[0042] The machining quality of the comparative electric spark deep small hole machining test includes surface morphology analysis and remelt layer thickness analysis of the machined surface. Surface morphology analysis can directly reflect the smoothness, flatness and processing defect conditions of the workpiece surface. By analyzing the surface, it can be determined whether common processing defects such as burns, cracks and pits occur during machining. These defects may be caused by poor discharge conditions, debris accumulation or carbon deposition, and surface morphology analysis can help evaluate whether ultrasonic-assisted electric spark machining significantly reduces these defects and optimizes the machining parameters. Remelt layer thickness analysis is crucial for evaluating the quality of electric spark machining. The remelt layer is a layer formed by local melting and solidification of the material during electric spark machining. Excessive thickness can affect the mechanical properties of the workpiece, especially in high-precision and high-strength applications such as aerospace parts. By analyzing the thickness of the remelt layer, the effect of machining parameters on surface quality can be determined, and ultrasonic-assisted technology can help reduce secondary discharge and abnormal discharge, thereby effectively reducing the thickness of the remelt layer and improving the surface quality of the workpiece.

[0043] In a specific embodiment, the ultrasonic wave direction includes horizontal, inclined 45 degrees and vertical directions. The vibration source device uses a total power of 1.8KW and a frequency of 40KHZ. Through orthogonal test, different ultrasonic auxiliary conditions are set, i.e. the ultrasonic generator is located in the horizontal, inclined 45° and vertical directions of the part as shown in Figure 4 The most optimal machining parameters are determined by process test of the three main factors in the ultrasonic electric spark deep small hole machining process. The specific parameters are shown in the table below.

[0044]

[0045] Through the research of ultrasonic electric spark machining technology, the problems of carbon deposition, chip removal and ionization elimination during electric spark deep small hole machining are improved, the machining efficiency is improved by 22.19%, the material removal rate is improved from 1.2022mm3 / h to 1.544mm3 / h, the diameter difference between the small hole aperture and the hole bottom is controlled within 0.02mm, and the actual value can reach 0.008mm.

[0046] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for designing an electrical discharge deep hole machining process, characterized in that, The method comprises the following steps: An ultrasonic device is designed to assist in chip removal during electric spark machining by ultrasonic vibration, and the power of the ultrasonic device, the position of the ultrasonic vibration source and the angle of the ultrasonic vibration source are all adjustable; Orthogonal tests are performed on electric spark machining of deep small holes under different ultrasonic influencing factors, including ultrasonic power, distance between the ultrasonic vibration source and the machining site and ultrasonic direction; The machining quality of the electric spark deep small hole machining test is compared to obtain the best ultrasonic influencing factor combination; The ultrasonic device is adjusted according to the best ultrasonic influencing factor combination, and the adjusted ultrasonic device is used as an auxiliary device for electric spark deep small hole machining; The ultrasonic device comprises a vibration source device (30) for generating ultrasonic waves and a fixed clamp for supporting the vibration source device (30), and the fixed clamp comprises a position adjusting assembly, an angle adjusting assembly and a clamping piece; The position adjusting assembly comprises a vertical rod (2) and a horizontal rod (20) perpendicular to each other, the bottom of the vertical rod (2) is fixed with a base (1), an adapter sleeve (3) is slidably arranged on the vertical rod along the length direction, the horizontal rod (20) is in sliding fit with the adapter sleeve (3), and the adapter sleeve (3) is provided with locking bolts for locking the vertical rod and the horizontal rod (20); The angle adjusting assembly is symmetrically arranged on both sides of the vibration source device (30), and each angle adjusting assembly comprises a mounting block (8), a fixed 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), the other end of the mounting block (8) is provided with a rotating shaft, the fixed block (10) is arranged on the fixed plate (4), the cover plate (9) is fixed on the fixed block (10), a lower semicircular groove is formed on the fixed 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 a shaft hole matched with the rotating shaft.

2. The electric spark deep small hole machining process design method according to claim 1, wherein: The clamping piece comprises two fixed plates (4) fixed on the horizontal rod (20), the vibration source device (30) is located between the two fixed plates (4) and connected with the fixed plates (4), and the length of the fixed plate (4) is not less than the maximum radius of the fan-shaped area swept by the vibration source device (30) during rotation, so as to avoid interference between the vibration source device (30) and the horizontal rod (20) during rotation.

3. The electric spark deep small hole machining process design method according to claim 2, wherein: A flat washer (11) is sleeved on the end of the rotating shaft of the mounting block (8) protruding out of the shaft hole, and a disc-shaped nut (12) is threadedly connected with the flat washer (11).

4. The electric spark deep small hole machining process design method according to claim 3, wherein: The vibration source device (30) comprises 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.

5. The electric spark deep small hole machining process design method according to claim 4, wherein: The comparison of the machining quality of the electric spark deep small hole machining test comprises surface topography analysis and remelted layer thickness analysis on the machined surface.

6. The method according to claim 1, wherein the ultrasonic wave direction includes horizontal, 45-degree inclined, and vertical directions.

7. The method according to claim 1, wherein the vibration source device (30) has a total power of 1.8 KW and a frequency of 40 KHZ. ​ ​

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