A method of hole making for a turbine blade

Abstract

The application relates to the field of special processing, in particular to a hole making method for a turbine blade. The hole making method provided by the application is divided into two steps, first, according to the spatial position and shape of the gas film hole to be machined of the turbine blade, electric spark forming machining is completed on all the gas film round holes and special-shaped gas film holes of the turbine blade; then, an electrolytic grinding composite machining head is called, the remelted layer with an expected thickness is removed through the combined action of electrochemical dissolution and mechanical grinding, and electrolytic grinding polishing of the inner wall of the gas film hole is realized. The application can solve the problem of the remelted layer left by electric spark machining of the gas film hole, and the sharp corner position in the gas film hole is rounded to avoid stress concentration.

Description

Technical Field

[0001] This invention relates to the field of special processing, specifically a method for drilling holes in turbine blades. Background Technology

[0002] Turbine blades are crucial hot-end components of aero-engines, operating under extremely high ambient temperatures and complex alternating load conditions for extended periods. Their operational stability and reliability are fundamental to the overall safety of the aero-engine. With increasing performance demands on aero-engines, turbine inlet gas temperatures are constantly rising, severely testing the temperature resistance of core hot-end components such as turbine blades. To ensure the safety and lifespan of turbine blades in high-temperature environments and improve their high-temperature resistance, in addition to enhancing the properties of high-temperature alloy materials and employing thermal barrier coating technology, most advanced aero-engine turbine blades both domestically and internationally utilize film cooling (FSL) designs. Cooling airflow is introduced into the hollow turbine blade cavity, flowing through cooling channels and exiting through film cooling holes distributed throughout the blade body. This forms a cooling film covering the blade, isolating the blade surface from the high-temperature combustion gases and carrying away some of the radiant heat from the combustion gases or bright flames, thus providing excellent protection for the blade surface. Therefore, film cooling holes are one of the key structural elements for improving the temperature resistance of aero-engine turbine blades. Especially with the development of next-generation aero-engines, higher requirements are placed on the quality and efficiency of film cooling hole processing to ensure the cooling effect and fatigue life of turbine blades.

[0003] Because blade materials are often high-temperature alloys, which are typically difficult to machine, and considering the high-quality machining requirements and tiny structural dimensions of film cooling holes, special machining methods are mainly used for film cooling hole processing, including electrical discharge machining (EDM), electrohydraulic beam machining, and femtosecond laser machining. Electrohydraulic beam machining eliminates the remelted layer on the hole wall, but its localization is poor, resulting in poor hole shape, larger inner orifice, and a higher risk of blade wall damage, leading to a low yield rate. Femtosecond laser machining eliminates the remelted layer on the hole wall, but due to the energy characteristics of pulsed lasers, it faces limitations such as difficulty in protecting the wall from damage and the inability to machine interference holes, as well as lower processing efficiency and higher costs. In contrast, EDM, based on spark discharge to melt and erode the material, offers advantages such as high processing efficiency, the ability to machine interference holes and irregularly shaped holes, and lower equipment and processing costs. However, the instantaneous high temperature generated during spark discharge results in a remelted layer on the EDM surface, containing numerous pores and microcracks, which easily lead to crack initiation and propagation, reducing fatigue life.

[0004] To control the remelted layer generated during electrical discharge machining (EDM), current methods mainly rely on process optimization to thin it or a combination of processes for removal. For example, Zhang Zhen et al. and HT Lee et al. have achieved a remelted layer thickness of <12 μm through process parameter optimization. However, process parameter optimization methods can only reduce the thickness of the remelted layer to a limited extent, and the current optimization results are not ideal. For thicker remelted layers and obvious microcracks, removal can only be achieved through secondary processes, such as abrasive flow or chemical polishing. To effectively reduce or even completely remove the remelted layer, research institutions at home and abroad are exploring new processes and technologies. Among them, the EDM-electrolysis composite machining method suffers from several drawbacks. The electrolysis time accumulates continuously with the machining feed, making it difficult to guarantee the dimensional accuracy of the hole. Furthermore, the short electrolysis time at the hole exit position results in unsatisfactory removal of the remelted layer near the hole opening. The combined EDM and electrolytic machining method first uses EDM to create the basic hole structure, and then electrolytically removes the remelted layer from the EDM-machined surface. However, due to the tiny gaps between the hole sidewalls and weak convection of the interstitial electrolyte, electrolytic products adhere to the hole wall surface or remain in the machining gap, deteriorating the properties of the interstitial electrolyte and resulting in uneven or even impossible removal of the remelted layer. The combined EDM and grinding method first uses EDM to create the basic hole structure, and then uses a micro-honing head to hone and remove the remelted layer from the EDM-machined surface. However, due to the small machining size, the hardness of the remelted layer material, the difficulty in manufacturing the grinding head, and its rapid wear, it is difficult to promote its use in actual production.

[0005] Therefore, researching a new process for drilling holes in turbine blades to achieve high-efficiency, high-quality, and zero-remelting-layer processing of film pores is an urgent problem to be solved in the field of special machining of turbine blades. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a method for drilling holes in turbine blades. The method for drilling holes in turbine blades provided by the present invention can achieve zero remelting layer while ensuring the accuracy of machining dimensions.

[0007] This invention provides a method for drilling holes in turbine blades, comprising the following steps:

[0008] S1) Perform electrical discharge machining to create holes in the turbine blade to be processed, forming film pores on the turbine blade to be processed;

[0009] S2) Electrolytic grinding is used to perform electrolytic grinding on the film holes on the turbine blades to be processed obtained in step S1).

[0010] The electrolytic grinding process specifically involves using the electrolytic grinding composite machining head as the negative electrode and the turbine blade to be processed as the positive electrode to perform electrolytic and grinding processes on the film pores on the turbine blade to be processed in an electrolyte solution; the peak voltage of the electrolytic pulse power supply is 20 V~60 V, the pulse width is 5 μs~100 μs, and the pulse interval is 5 μs~100 μs.

[0011] The inventors of this application have creatively discovered that applying electrolytic grinding to the surface finishing process of film holes formed by electrical discharge machining on turbine blades can achieve zero remelting layer while ensuring machining dimensional accuracy.

[0012] This invention first uses electrical discharge machining (EDM) to create holes in the turbine blade, forming film cooling holes. Based on the spatial position and shape of the film cooling holes on the turbine blade, this invention sets the initial relative position between the EDM spindle and the turbine blade, controls the relative movement between the EDM spindle and the turbine blade, and completes the creation of all film cooling holes on the turbine blade one by one.

[0013] Specifically, the film gas holes formed by this invention include film gas circular holes and film gas shaped holes; the film gas shaped holes are composed of diffuser sections and straight sections. The process of making film gas circular holes by electrical discharge machining in this invention is as follows: before machining each film gas circular hole, the relative position between the electrical discharge machining spindle head and the turbine blade is first set, and then a hollow electrode wire is loaded on the electrical discharge machining spindle head. With the help of high-pressure internal flushing fluid, external flushing fluid and rotational motion to drive the working medium to be renewed, the electrode wire is controlled to feed downward and the electrode wear is compensated in time to machine the film gas circular hole.

[0014] The process of making gas film shaped holes by electrical discharge machining in this invention is as follows: before machining each gas film shaped hole, the relative position between the electrical discharge machining spindle head and the turbine blade is first set, and then the gas film shaped hole is machined by forming electrode machining method or three-dimensional scanning milling machining method.

[0015] The electrical discharge machining (EDM) parameters described in this invention are as follows: peak voltage of the pulse power supply is 60 V to 140 V, pulse width is 1 μs to 20 μs, pulse interval is 1 μs to 20 μs, and electrode rotation speed is 50 r / min to 200 r / min. By employing a high-frequency, narrow-pulse-width pulse power supply and an optimized EDM process, this invention reduces the surface remelted layer of the formed film-forming circular holes and irregularly shaped holes to approximately 10 μm, and ensures uniform remelted layer thickness.

[0016] After forming film cooling holes on the turbine blade to be processed, this invention uses an electrolytic grinding composite machining head to electrolytic grind the film cooling holes on the turbine blade to be processed obtained in step S1) to remove the remelted layer on the surface of the film cooling holes. In this invention, if the film cooling hole is a circular film cooling hole, the electrolytic grinding composite machining head passes through and extends out of the circular film cooling hole to electrolytic grind the inner wall of the film cooling hole. Specifically, the process of removing the remelted layer on the surface of the circular film cooling hole by electrolytic grinding in this invention is as follows: before electrolytic grinding each circular film cooling hole, according to the spatial position and shape of the film cooling hole to be electrolytically ground on the turbine blade, the initial relative position between the electrolytic grinding composite machining head and the turbine blade is set so that the electrolytic grinding composite machining head extends into the circular film cooling hole, and through hole shape and position model calculation, the end of the electrolytic grinding composite machining head slightly extends out of the hole, so that when the electrolytic grinding composite machining head rotates, the electrolytic grinding composite machining can be applied to all positions of the inner wall of the circular film cooling hole.

[0017] In this invention, if the air film pore is an irregularly shaped air film pore, the process of removing the remelted layer on the surface of the irregularly shaped air film pore is divided into two stages: removal of the remelted layer in the diffuser section and removal of the remelted layer in the straight section; the removal of the remelted layer in the diffuser section and the removal of the remelted layer in the straight section are not in any particular order.

[0018] The process of removing the remelted layer from the diffuser section of the present invention includes: electrolytic grinding of the electrolytic grinding composite machining head around the inner wall of the diffuser section of the film gas hole. Specifically, firstly, based on the spatial position and shape of the film gas hole to be electrolytically ground on the turbine blade, the initial relative position between the electrolytic grinding composite machining head and the turbine blade is set, so that the sidewall of the electrolytic grinding composite machining head is parallel to and in contact with one sidewall of the diffuser hole. Then, based on the three-dimensional model of the irregular hole, the relative motion path between the electrolytic grinding composite machining head and the turbine blade is planned, so that the electrolytic grinding composite machining head moves around the sidewall of the diffuser structure once or several times, and the remelted layer on the surface of the diffuser section of the film gas hole is removed by the electrolytic grinding composite machining action.

[0019] The process of removing the remelted layer from the straight hole section according to the present invention includes: passing the electrolytic grinding composite machining head through and extending out of the straight hole section of the film gas hole and performing electrolytic grinding around the inner wall of the straight hole section. Specifically, firstly, based on the spatial position and shape of the film gas hole to be electrolytically ground on the turbine blade, the initial relative position between the electrolytic grinding composite machining head and the turbine blade is set, so that the electrolytic grinding composite machining head extends into the machined hole. Through hole shape and position model calculation, the end of the electrolytic grinding composite machining head slightly extends out of the hole, so that when the electrolytic grinding composite machining head rotates, the electrolytic grinding composite machining can be applied to all positions of the inner wall of the hole. At this position, the electrolytic grinding composite machining is started until the remelted layer on the surface of the straight hole section of the film gas hole is removed.

[0020] This invention employs an electrolytic grinding composite machining head to electrolytically grind the film cooling holes on the turbine blade to be machined. The ratio of the outer diameter of the electrolytic grinding composite machining head to the diameter of the film cooling hole is (0.35~0.45):0.5. Specifically, the ratio of the outer diameter of the electrolytic grinding composite machining head to the diameter of the film cooling circular hole is (0.35~0.45):0.5, and the ratio of the outer diameter of the electrolytic grinding composite machining head to the diameter of the straight section of the film cooling irregular hole is (0.35~0.45):0.5.

[0021] The electrolytic grinding composite machining head used in the electrolytic grinding process of this invention comprises a conductive substrate, a conductive binder disposed on the substrate, and abrasive grains disposed on the substrate. The conductive binder is selected from at least one of cast iron binders, nickel binders, nickel alloy binders, tungsten carbides, or bronze binders, preferably bronze binders. The main component of the abrasive grains is cubic boron nitride or corundum. The abrasive grains of this invention are distributed on the sidewalls of the electrolytic grinding composite machining head in a randomly distributed, sparse manner. Combined with the rotational motion of the electrolytic grinding composite machining head and the action of external fluid, this disturbs the flow field distribution within the machining gap, promoting electrolyte renewal.

[0022] This invention uses the electrolytic grinding composite machining head as the negative electrode and the turbine blade to be processed as the positive electrode. The turbine blade is electrolyzed in an electrolyte solution, while the electrolytic grinding composite machining head simultaneously grinds the film gas holes on the turbine blade. Specifically, the conductive substrate and conductive binder of the electrolytic grinding composite machining head are used as the negative electrode, and the turbine blade to be processed is used as the positive electrode. The turbine blade is electrolyzed in an electrolyte solution, while the electrolytic grinding composite machining head simultaneously grinds the film gas holes on the turbine blade. The electrolyte solution of this invention is selected from at least one of NaNO3, NaClO3, NaCl, or Na3Cit and related combinations thereof, preferably a combination of NaNO3 and Na3Cit. The peak voltage of the pulse power supply for electrolysis in this invention is 20 V to 60 V, the pulse width is 5 μs to 100 μs, and the pulse interval is 5 μs to 100 μs. The rotational speed of the electrolytic grinding process is 800 r / min to 1200 r / min; the feed rate of the electrolytic grinding process is 0.3 mm / s to 0.5 mm / s.

[0023] The electrolytic grinding speed described in this invention is 800 r / min to 1200 r / min; wherein, if the air film hole is a circular air film hole, the electrolytic grinding time is 5 s to 10 s. If the air film hole is a non-circular air film hole, in step S2), an electrolytic grinding composite head is used to perform electrolytic grinding by feeding around the inner wall of the diffusion hole section of the air film hole at a feed speed of 0.3 mm / s to 0.5 mm / s for 2 to 3 revolutions, and the electrolytic grinding composite head is passed through and extends out of the straight hole section of the air film hole and performs electrolytic grinding around the inner wall of the straight hole section for 5 s to 10 s.

[0024] like Figure 1 As shown, Figure 1 This is a schematic diagram of the electrolytic grinding composite machining process, where 11 is the high-temperature alloy matrix, 22 is the binder between the electrolytic grinding composite machining head matrix and the abrasive grains, 23 is the abrasive grain of the electrolytic grinding composite machining head, 41 is the negative electrode of the electrolytic grinding power supply, and 42 is the positive electrode of the electrolytic grinding power supply. This invention connects the conductive matrix and conductive binder to the negative electrode of the electrolytic grinding power supply, where a cathodic hydrogen evolution reaction occurs on the binder surface. The turbine blades are connected to the positive electrode of the electrolytic grinding power supply. Due to the close distance between the surface to be machined and the electrolytic grinding composite machining head, the potential gradient between them is large, resulting in a high current density on the surface to be machined. An anodic oxidation reaction occurs on the surface to be machined, dissolving the remelted metal layer. Additionally, part of the remelted metal layer surface is directly oxidized to form a metal oxide with a thickness on the nanometer scale. Because the metal oxide is non-conductive and has a dense structure, the internal remelted layer is difficult to participate in the dissolution reaction. However, due to the scraping action of the abrasive grains on the matrix, scratches are created on the surfaces of the remelted layer and passivation layer, exposing the internal remelted layer, which is then dissolved. Therefore, electrolysis and grinding complement each other, rapidly removing the remelted layer while improving the surface quality of the film pores. Furthermore, due to the current concentration effect at the sharp corners in the film pores, the material is eroded quickly during electrolytic processing, resulting in a rounded effect at the sharp corners, thereby reducing stress concentration and improving the fatigue life of the blades.

[0025] This invention provides a method for drilling holes in turbine blades. This method is based on a combined electrical discharge machining (EDM) and electrolytic grinding process. Compared to the EDM-electrolytic combined drilling method, it can achieve zero remelting layer while ensuring dimensional accuracy, and it has lower requirements for the corrosion resistance of the multi-functional spindle used in EDM. Compared to the combined EDM-electrolytic method, the mechanical scraping action of the abrasive grains can mitigate the passivation effect during electrolysis, and it complements the chemical removal and softening effects of electrolysis, increasing the remelting layer removal rate. Simultaneously, the rotating turbulence of the abrasive grains accelerates the renewal of the interstitial electrolyte, increasing the uniformity of remelting layer removal. Compared to the combined EDM-grinding method, the electrochemical-based material removal effectively avoids rapid wear of the grinding head, while improving processing efficiency and quality. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the mechanism of the electrolytic grinding composite machining process;

[0027] Figure 2 This is a schematic diagram of the drilling method for turbine blades according to the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of an electrolytic grinding composite machining head;

[0029] Figure 4 A schematic diagram of the machining result of a single film-forming hole in the EDM forming process and the distribution of the remelted layer on its surface.

[0030] Figure 5 A schematic diagram of the machining result of a gas film shaped hole and the distribution of its surface remelted layer in the EDM forming result of a single gas film hole;

[0031] Figure 6 Schematic diagram of the process for removing the remelted layer in the combined machining of air film circular holes by electrolytic grinding;

[0032] Figure 7 A schematic diagram of the process for removing the remelted layer on the surface of the diffusion structure section during the composite machining of electrolytic grinding for gas film shaped holes;

[0033] Figure 8 This is a schematic diagram of the process for removing the remelted layer on the surface of the straight hole structure section during the electrolytic grinding composite machining of air-film irregular holes. Detailed Implementation

[0034] This invention discloses a method for drilling holes in turbine blades. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to implement and apply the technology of this invention.

[0035] The turbine blade hole-making method provided by this invention mainly includes a film hole electrical discharge machining process and an electrolytic grinding composite machining process to remove the remelted layer. For example... Figure 2 As shown, Figure 2 This is a schematic diagram of the drilling method for turbine blades according to an embodiment of the present invention.

[0036] In this embodiment, the electrolytic grinding composite machining head consists of a copper substrate, a bronze binder, and CBN abrasive grains. The outer diameter of the functional structure of the electrolytic grinding composite machining head is 0.38 mm. The abrasive grains are distributed on the sidewalls of the electrolytic grinding composite machining head in a randomly distributed and sparse manner. Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of an electrolytic grinding composite machining head, where 2 is the electrolytic grinding composite machining head, 21 is the electrolytic grinding composite machining head substrate, 22 is the bonding agent between the electrolytic grinding composite machining head substrate and the abrasive grains, and 23 is the abrasive grains of the electrolytic grinding composite machining head.

[0037] The present invention will be further described below with reference to the embodiments:

[0038] Example 1

[0039] Taking a turbine blade with 0.5 mm diameter circular holes and 0.5 mm diameter scoop holes as an example:

[0040] Based on the spatial location and shape of the film cooling holes to be machined on the turbine blade, the machining sequence and control program for each film cooling hole are planned. Positioning and clamping are achieved using blade tenons. A hollow electrode wire with an outer diameter of 0.38 mm is clamped using an EDM (Electrical Discharge Machining) composite spindle head. The hole to be machined is adjusted to the work position using a five-axis system, and the film cooling hole machining control program is initiated, including motion unit control, EDM power supply control, fluid flushing system control, and machining process detection, identification, and feedback control. A hollow electrode wire with an outer diameter of 0.38 mm is used to form the circular holes and hopper holes (irregularly shaped holes) on the turbine blade. The diffuser section of the hopper hole is achieved using a scanning milling method. Figure 4 and Figure 5 As shown, Figure 4 This is a schematic diagram of the gas film circular hole machining result and the distribution of its surface remelted layer in the EDM forming result of a single gas film hole, where 1-turbine blade, 11-high temperature alloy substrate, 13-gas film circular hole, and 131-gas film circular hole wall remelted layer. Figure 5 This is a schematic diagram of the machining results of a special-shaped air film hole and the distribution of its surface remelted layer in the EDM forming of a single air film hole, where 1-turbine blade, 11-high temperature alloy substrate, 12-special-shaped air film hole, 121-remelted layer of the hole wall of the diffuser section of the special-shaped air film hole, and 122-remelted layer of the hole wall of the circular section of the special-shaped air film hole.

[0041] In this embodiment, the electrical discharge machining (EDM) parameters are as follows: peak voltage of the pulse power supply is 100 V, pulse width is 4 μs, pulse interval is 12 μs, and electrode rotation speed is 200 r / min. The inner diameter of the machined circular hole is 0.46 mm, and the average remelted layer thickness is 13 μm. By utilizing a high-frequency, narrow-pulse-width pulse power supply and optimized EDM technology, the remelted layer thickness on the surface of film-forming circular holes and irregularly shaped film holes can be reduced to approximately 10 μm, and the remelted layer thickness is uniform.

[0042] After completing the forming of the film cooling holes, the EDM spindle head is switched to an electrolytic grinding composite machining head. Based on the spatial location and shape of the film cooling holes on the turbine blades, a machining control program is planned for the electrolytic grinding composite machining of each film cooling hole to remove the remelted layer. This program includes motion unit control, electrolytic machining power supply control, fluid flushing system control, machining process detection, identification, and feedback control. The electrolytic grinding composite machining method removes the remelted layer of the expected thickness and achieves electrolytic grinding polishing of the inner wall of the film cooling holes.

[0043] In the removal of the remelted layer from film-forming holes, the initial relative position between the electrolytic grinding composite machining head and the turbine blade is first set according to the spatial location of the film-forming hole to be machined. This allows the electrolytic grinding composite machining head to extend into the machined hole. Through hole shape and position model calculations, the end of the electrolytic grinding composite machining head slightly protrudes from the hole, meaning that when the electrolytic grinding composite machining head rotates, the electrolytic grinding composite machining can act on all positions of the hole's inner wall. Optimized electrolyte composition, electrolytic machining power supply parameters, and electrolytic grinding composite machining action time are used to remove the remelted layer on the surface of the film-forming hole, achieving zero remelted layer. For example... Figure 6 As shown, Figure 6 A schematic diagram of the process for removing the remelted layer in the composite machining of gas film circular holes by electrolytic grinding, where 1-turbine blade and 3-working fluid.

[0044] Remelted layer removal in irregularly shaped holes includes remelted layer removal in the diffuser section and remelted layer removal in the straight hole section. In diffuser section remelted layer removal, firstly, based on the spatial location and shape of the film cooling hole to be machined on the turbine blade, the initial relative position between the electrolytic grinding composite machining head and the turbine blade is set, ensuring the sidewall of the electrolytic grinding composite machining head is parallel to and in contact with one sidewall of the diffuser hole. Then, based on the 3D model of the irregularly shaped hole, the relative motion path between the electrolytic grinding composite machining head and the turbine blade is planned, causing the electrolytic grinding composite machining head to move around the sidewall of the diffuser structure one or several times. The remelted layer on the surface of the diffuser section of the film cooling hole is removed through electrolytic grinding composite machining. By optimizing the motion path, electrolyte composition, and electrolytic machining power supply parameters, zero remelted layer in the diffuser section is achieved. Figure 7 As shown, Figure 7 This is a schematic diagram of the process for removing the remelted layer on the surface of the diffusion structure section during the electrolytic grinding composite machining of air-film irregular holes.

[0045] In the removal of the remelted layer in the straight hole section, the initial relative position between the electrolytic grinding composite machining head and the turbine blade is first set according to the spatial position and shape of the film gas hole to be machined on the turbine blade. This allows the electrolytic grinding composite machining head to extend into the machined hole. Through hole shape and position model calculations, the end of the electrolytic grinding composite machining head slightly protrudes from the hole, meaning that when the electrolytic grinding composite machining head rotates, the electrolytic grinding composite machining can act on all positions of the hole's inner wall. By employing optimized electrolyte composition, electrolytic machining power supply parameters, and electrolytic grinding composite machining action time, the remelted layer on the surface of the straight hole structure section of the film gas hole is removed, achieving zero remelted layer in the straight hole section. For example... Figure 8 As shown, Figure 8 This is a schematic diagram of the process for removing the remelted layer on the surface of the straight hole structure section during the electrolytic grinding composite machining of air-film irregular holes.

[0046] In this embodiment, the electrolytic grinding composite machining parameters are as follows: the peak voltage of the electrolytic machining pulse power supply is 50 V, the pulse width and pulse interval are both 20 μs, and the rotation speed of the electrolytic grinding composite machining head is 1000 r / min. The electrolyte is a NaNO3 + Na3Cit solution with a conductivity of 30 mS / cm, wherein Na3Cit is 0.01 mol / L. The remelted layer in the gas film circular hole is removed by electrolytic grinding composite machining for 10 s. In the scoop hole, during the removal of the remelted layer in the diffuser hole section, the feed rate of electrolytic grinding composite machining is 0.4 mm / s, and it feeds around the diffuser hole circumferentially twice. During the removal of the remelted layer in the straight hole section, the electrolytic grinding composite machining is performed for 10 s to remove the remelted layer.

[0047] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for drilling holes in turbine blades, characterized in that, Includes the following steps: S1) Perform electrical discharge machining to create holes in the turbine blade to be processed, forming film pores on the turbine blade to be processed; S2) Electrolytic grinding is used to perform electrolytic grinding on the film holes on the turbine blades to be processed obtained in step S1). The electrolytic grinding process specifically involves using the electrolytic grinding composite machining head as the negative electrode and the turbine blade to be processed as the positive electrode to simultaneously perform electrolytic and grinding processes on the film pores on the turbine blade to be processed in the electrolyte. The peak voltage of the pulse power supply for electrolysis is 20 V to 60 V, the pulse width is 5 μs to 100 μs, and the pulse interval is 5 μs to 100 μs.

2. The hole-making method according to claim 1, characterized in that, In step S1), the air film pore is a circular air film pore; In step S2), the electrolytic grinding composite machining head passes through and extends out of the air film hole and performs electrolytic grinding around the inner wall of the air film hole.

3. The hole-making method according to claim 1, characterized in that, In step S1), the air film pore is a non-standard air film pore, which is composed of a diffuser section and a straight section. In step S2), the electrolytic grinding composite machining head is used to perform electrolytic grinding around the inner wall of the diffusion hole section of the air film hole; the electrolytic grinding composite machining head is passed through and extends out of the straight hole section of the air film hole and is used to perform electrolytic grinding around the inner wall of the straight hole section.

4. The hole-making method according to claim 1, characterized in that, The ratio of the outer diameter of the electrolytic grinding composite machining head in step S2) to the diameter of the air film hole in step S1) is 0.7~0.

9.

5. The hole-making method according to any one of claims 1 to 4, characterized in that, In step S1), the parameters for the electrical discharge machining are as follows: The peak voltage of the pulse power supply is 60 V~140 V, the pulse width is 1 μs~20 μs, the pulse interval is 1 μs~20 μs, and the electrode rotation speed is 50 r / min~200 r / min.

6. The hole-making method according to any one of claims 1 to 4, characterized in that, In step S2), the electrolyte is selected from at least one of NaNO3, NaClO3, NaCl, or Na3Cit.

7. The hole-making method according to any one of claims 1 to 4, characterized in that, In step S2), the conductivity of the electrolyte is 10 mS / cm to 70 mS / cm.

8. The hole-making method according to any one of claims 1 to 4, characterized in that, If the air film hole described in step S1) is an air film circular hole, then the electrolytic grinding time described in step S2) is 5 s~10 s; If the air film hole described in step S1) is an irregularly shaped air film hole, then in step S2), an electrolytic grinding composite machining head is used to perform electrolytic grinding by feeding around the inner wall of the diffusion hole section of the air film hole at a feed speed of 0.3 mm / s to 0.5 mm / s for 1 to 3 revolutions. The electrolytic grinding composite machining head is then passed through and extended out of the straight hole section of the air film hole and performs electrolytic grinding around the inner wall of the straight hole section for 5 to 10 seconds.

9. The hole-making method according to any one of claims 1 to 4, characterized in that, In step S2), the electrolytic grinding composite machining head includes a conductive substrate, a conductive binder disposed on the conductive substrate, and abrasive grains disposed on the substrate; The conductive binder is selected from at least one of cast iron binders, nickel binders, nickel alloy binders, tungsten carbides, or bronze binders.

10. The hole-making method according to claim 9, characterized in that, The abrasive particles are arranged in a sparse, randomly distributed manner.

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