Turbine blade hole making method

Abstract

The invention relates to the field of non-traditional machining, in particular to a hole forming method for a turbine blade. The hole making method provided by the invention comprises two steps: firstly, according to the spatial position and shape of a to-be-processed gas film hole of the turbine blade, completing electric spark forming processing of all gas film round holes and special-shaped gas film holes in the turbine blade; and then an electrolytic grinding combined machining head is used, the remelting layer with the expected thickness is removed through the combined action of electrochemical dissolution and mechanical grinding, and electrolytic grinding and polishing of the inner wall of the air film hole are achieved. According to the method, the problem of a remelting layer remained in the film hole in electric spark machining can be solved, the sharp corner position in the film hole is rounded, and stress concentration is avoided.

Description

Technical Field

[0001] The invention relates to the field of special processing, in particular to a method for making holes in turbine blades. Background Art

[0002] Turbine blades are important hot-end components of aircraft engines. They have been in service for a long time under extremely high ambient temperatures and complex alternating load conditions. Their working stability and reliability are the basis for the safety of the entire aircraft engine. With the increase in the demand for aircraft engine performance, the temperature of the gas before the turbine continues to rise, which greatly tests the temperature-bearing capacity of core hot-end components such as turbine blades. In order to ensure the service safety and life of turbine blades in high-temperature environments and improve the high-temperature resistance of turbine blades, in addition to improving the performance of high-temperature alloy materials and adopting thermal barrier coating technology, most of the advanced aircraft engine turbine blades at home and abroad currently adopt a film cooling design scheme. The cooling airflow is introduced into the inner cavity of the hollow turbine blade, so that it flows through the cooling channel and is ejected through the film holes distributed on the blade body to form a cooling air film covering the blade, isolating the blade surface from the high-temperature gas, and taking away part of the radiant heat of the high-temperature gas or bright flame on the wall, thereby playing a good protective role on the blade surface. Therefore, the film hole is one of the key structures to improve the temperature-bearing capacity of aircraft engine turbine blades. Especially with the development of a new generation of aircraft engines, in order to ensure the cooling effect and fatigue life of turbine blades, higher requirements are put forward for the quality and efficiency of film hole processing.

[0003] Since blade materials are often high-temperature alloys, which are typical difficult-to-process materials, coupled with the high-quality processing requirements and tiny structural dimensions of air film holes, the processing of air film holes mainly adopts special processing methods, including electric spark, electro-hydraulic beam and femtosecond laser. Among them, the hole wall of the electro-hydraulic beam hole has no remelting layer, but the processing localization is poor, resulting in poor hole shape, large inner hole mouth, and easy damage to the blade wall, and low processing qualification rate. There is no remelting layer on the hole wall of the femtosecond laser hole, but due to the characteristics of pulsed laser energy release, femtosecond laser processing always has the limitations of difficulty in protecting the wall from damage and inability to process interference holes, and the processing efficiency is low and the processing cost is high. In contrast, electro-spark processing is based on spark discharge to melt and etch materials, and has the advantages of high processing efficiency, processing interference holes and special-shaped holes, and low equipment and processing costs. However, due to the instantaneous high temperature generated during the spark discharge process, a remelting layer exists on the surface of the electro-spark processing. The remelting layer contains a large number of defects such as pores and microcracks, which can easily lead to the generation and expansion of cracks and reduce fatigue life.

[0004] In order to control the remelting layer produced by EDM, the current process mainly relies on process optimization thinning or combined process removal. For example, Zhang Zhen et al., HT Lee et al. achieved the control of the remelting layer <12 μm by optimizing the process parameters, but the process parameter optimization method can only reduce the thickness of the remelting layer to a limited extent, and the current optimization results are not ideal. For thicker remelting layers and obvious microcracks, they can only be removed through secondary processes, such as using abrasive flow and chemical grinding methods to remove the remelting layer after processing. In order to effectively reduce or even completely remove the remelting layer, research institutions at home and abroad are trying to explore new processes and technologies. Among them, the EDM electrolysis composite machining method cannot guarantee the dimensional accuracy of the hole on the one hand because the electrolysis time accumulates continuously with the processing feed process, and on the other hand, due to the short electrolysis time at the hole outlet, the removal effect of the remelting layer near the hole mouth is not ideal. The combined EDM and electrolytic machining method first uses EDM to machine the base hole structure, and then uses electrolytic machining to remove the remelted layer on the EDM surface. However, due to the small gap between the hole side walls and the weak convection of the gap electrolyte, the electrolytic products adhere to the hole wall surface or remain in the machining gap, which deteriorates the properties of the gap electrolyte, and the remelted layer removal effect is uneven, or even difficult to remove. The combined EDM and grinding method first uses EDM to machine the base hole structure, and then uses a tiny honing head to hone to remove the remelted layer on the EDM surface. However, due to the small machining size and the hard material of the remelted layer, the grinding head is difficult to manufacture and wears out quickly, making it difficult to promote and use in actual production.

[0005] Therefore, studying a new process method for making holes in turbine blades to achieve high-efficiency, high-quality, and zero-remelting layer processing of air film holes is an urgent problem to be solved in the field of special processing 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 making holes in turbine blades. The method for making holes in turbine blades provided by the present invention can ensure processing dimensional accuracy while achieving zero remelting layer.

[0007] The present invention provides a method for making holes in a turbine blade, comprising the following steps:

[0008] S1) performing electrospark machining on the turbine blade to be processed to form a hole, thereby forming an air film hole on the turbine blade to be processed;

[0009] S2) using an electrolytic grinding composite processing head to electrolytically grind the air film holes on the turbine blade to be processed obtained in step S1);

[0010] The electrolytic grinding process is specifically as follows: using the electrolytic grinding composite processing head as the negative electrode and the turbine blade to be processed as the positive electrode, the air film holes on the turbine blade to be processed are electrolyzed and ground in an electrolyte; 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 the present application creatively discovered that applying the electrolytic grinding process to the surface finishing process of the air film holes formed by electric spark machining of turbine blades can achieve zero remelting layer while ensuring the machining dimensional accuracy.

[0012] The present invention first performs electrospark machining on a turbine blade to be machined to form air film holes on the turbine blade to be machined. The present invention sets the initial relative position between the electrospark machining spindle head and the turbine blade according to the spatial position and shape of the air film holes to be machined on the turbine blade, controls the relative movement between the electrospark machining spindle head and the turbine blade, and completes the hole making of all the air film holes to be machined on the turbine blade one by one.

[0013] Specifically, the air film holes formed by the present invention include air film circular holes and air film irregular holes; the air film irregular holes are composed of diffusion hole segments and straight hole segments. The process of the present invention for making air film circular holes by electrospark machining is as follows: before machining each air film circular hole, the relative position between the electrospark machining spindle head and the turbine blade is first set, and then the electrospark machining spindle head is used to load the hollow electrode wire, and the high-pressure internal flushing liquid, external flushing liquid and rotational motion are used to drive the renewal of the working medium, control the downward feeding of the electrode wire, and timely compensate for the electrode loss to machine the air film circular hole.

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

[0015] The parameters of the EDM machining of the present invention are as follows: the peak voltage of the pulse power supply is 60 V to 140 V, the pulse width is 1 μs to 20 μs, the pulse interval is 1 μs to 20 μs, and the electrode rotation speed is 50 r / min to 200 r / min. The present invention reduces the surface remelting layer of the formed air film circular hole and air film special-shaped hole to about 10 μm by adopting a high-frequency narrow pulse width pulse power supply and an optimized EDM process, and the thickness of the remelting layer is uniform.

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

[0017] In the present invention, if the air film hole is an air film irregular hole, the process of removing the remelted layer on the surface of the air film irregular hole is divided into two stages: removal of the remelted layer in the diffusion hole section and removal of the remelted layer in the straight hole section; the removal of the remelted layer in the diffusion hole section and the removal of the remelted layer in the straight hole section are performed in no particular order.

[0018] The process of removing the remelted layer of the diffusion hole segment of the present invention includes: performing electrochemical grinding on the inner wall of the diffusion hole segment of the air film hole by surrounding the electrochemical grinding composite processing head. Specifically, firstly, according to the spatial position and shape of the air film hole to be electrochemically ground on the turbine blade, the initial relative position between the electrochemical grinding composite processing head and the turbine blade is set, so that the side wall of the electrochemical grinding composite processing head is parallel to and in contact with a side wall of the diffusion hole, and then the relative movement path between the electrochemical grinding composite processing head and the turbine blade is planned according to the three-dimensional model of the special-shaped hole, so that the electrochemical grinding composite processing head moves around the side wall of the diffusion structure for one or several cycles, and the remelted layer on the surface of the diffusion structure segment of the air film hole is removed by the electrochemical grinding composite processing action.

[0019] The process of removing the remelted layer of the straight hole section of the present invention includes: passing the electrolytic grinding composite processing head through and extending out of the straight hole section of the air film hole and surrounding the inner wall of the straight hole section for electrolytic grinding. Specifically, firstly, according to the spatial position and shape of the air film hole to be electrolytically ground on the turbine blade, the initial relative position between the electrolytic grinding composite processing head and the turbine blade is set, so that the electrolytic grinding composite processing head extends into the processed hole, and through the hole shape model calculation, the end of the electrolytic grinding composite processing head is slightly extended out of the hole, so that when the electrolytic grinding composite processing head rotates, the electrolytic grinding composite processing can act on all positions of the inner wall of the hole, and the electrolytic grinding composite processing is started at this position until the remelted layer on the surface of the straight hole structure section of the air film hole is removed.

[0020] The present invention uses an electrolytic grinding composite processing head to perform electrolytic grinding on the air film hole on the turbine blade to be processed, and the ratio of the outer diameter of the electrolytic grinding composite processing head to the diameter of the air film hole is (0.35-0.45):0.5. Specifically, the ratio of the outer diameter of the electrolytic grinding composite processing head to the diameter of the air film circular hole is (0.35-0.45):0.5, and the ratio of the outer diameter of the electrolytic grinding composite processing head to the diameter of the straight hole section of the air film special-shaped hole is (0.35-0.45):0.5.

[0021] The electrolytic grinding composite processing head used in the electrolytic grinding process of the present invention comprises a conductive substrate, a conductive binder arranged on the substrate, and abrasive particles arranged on the substrate; the conductive binder is selected from at least one of a cast iron binder, a nickel binder, a nickel alloy binder, a tungsten carbide, or a bronze binder, preferably a bronze binder; the main component of the abrasive particles is cubic boron nitride or corundum. The abrasive particles of the present invention are distributed on the side wall of the electrolytic grinding composite processing head, and a sparse distribution method of random distribution is adopted, combined with the rotational motion of the electrolytic grinding composite processing head and the external flushing liquid action, to disturb the flow field distribution in the processing gap and promote the renewal of the electrolyte.

[0022] The present invention uses the electrolytic grinding composite processing head as the negative electrode, the turbine blade to be processed as the positive electrode, electrolyzes the turbine blade to be processed in the electrolyte, and uses the electrolytic grinding composite processing head to grind the air film holes on the turbine blade to be processed. Specifically, the conductive substrate and conductive binder of the electrolytic grinding composite processing head are used as the negative electrode, the turbine blade to be processed is used as the positive electrode, the turbine blade to be processed is electrolyzed in the electrolyte, and the air film holes on the turbine blade to be processed are ground by the electrolytic grinding composite processing head. The electrolyte of the present invention is selected from at least one of NaNO3, NaClO3, NaCl or Na3Cit and related combination component electrolytes, preferably a combination electrolyte of NaNO3 and Na3Cit. The peak voltage of the pulse power supply for electrolysis of the present invention is 20 V~60 V, the pulse width is 5 μs~100 μs, and the pulse interval is 5 μs~100 μs. The rotation speed of the electrolytic grinding process is 800 r / min~1200 r / min; the feed speed of the electrolytic grinding process is 0.3 mm / s~0.5 mm / s.

[0023] The rotation speed of the electrolytic grinding process of the present invention is 800 r / min~1200 r / min; wherein, if the air film hole is an air film circular hole, the electrolytic grinding process time is 5 s~10 s. If the air film hole is an air film irregular hole, then in step S2), the electrolytic grinding composite processing head is used to feed 2~3 circles around the inner wall of the diffusion hole section of the air film hole at a feed speed of 0.3 mm / s~0.5 mm / s for electrolytic grinding, and the electrolytic grinding composite processing head is passed through and extended out of the straight hole section of the air film hole and around the inner wall of the straight hole section for electrolytic grinding for 5 s~10 s.

[0024] like Figure 1 As shown, Figure 1 It is a schematic diagram of the mechanism of the electrolytic grinding composite processing process, wherein 11-high temperature alloy substrate, 22-binder of the electrolytic grinding composite processing head substrate and abrasive, 23-abrasive of the electrolytic grinding composite processing head, 41-negative electrode of the electrolytic processing power supply, and 42-positive electrode of the electrolytic processing power supply. The present invention connects the conductive substrate and the conductive binder to the negative electrode of the electrolytic processing power supply, and a cathode hydrogen evolution reaction occurs on the surface of the binder. The turbine blade is connected to the positive electrode of the electrolytic processing power supply. Since the distance between the surface to be processed and the electrolytic grinding composite processing head is close, the potential gradient between the two is large, and the current density of the surface to be processed is large, an anodic oxidation reaction occurs on the surface to be processed, and the remelting layer metal is dissolved. In addition, part of the metal surface of the remelting layer is directly oxidized to form a metal oxide with a thickness of nm. Since the metal oxide is non-conductive and has a dense structure, it is difficult for the internal remelting layer to participate in the dissolution reaction. However, due to the scratching effect of the abrasive on the substrate, the surface of the remelting layer and the passivation layer is scratched, so that the internal remelting layer is exposed and then dissolved. Therefore, electrolysis and grinding complement each other, improving the surface quality of the air film hole while quickly removing the remelted layer; and due to the current concentration effect at the sharp corners of the air film hole, the material is etched away quickly during electrolytic processing, making the sharp corners present a rounded effect, thereby reducing stress concentration and improving the fatigue life of the blade.

[0025] The present invention provides a method for making holes in turbine blades. The method for making holes in turbine blades provided by the present invention is based on a composite machining process of electric spark and electrolytic grinding. Compared with the composite machining method of electric spark and electrolytic processing, it can achieve zero remelting layer while ensuring the machining size accuracy, and has low requirements on the corrosion resistance of the multifunctional spindle of electric spark machining. Compared with the combined machining method of electric spark and electrolytic processing, the mechanical scraping action of abrasive particles can alleviate the influence of the passivation effect in electrolysis, and complement the chemical removal and chemical softening action of electrolysis to increase the removal speed of the remelting layer; at the same time, the rotational turbulence action of abrasive particles can accelerate the renewal of the gap electrolyte and increase the uniformity of the removal of the remelting layer. Compared with the combined machining method of electric spark and grinding, the material removal method mainly based on electrochemistry can effectively avoid the rapid wear of the grinding head, while improving the efficiency and quality of processing. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0027] Figure 2 It is a schematic flow chart of the method for making holes in turbine blades according to the present invention;

[0028] Figure 3 It is a schematic diagram of the structure of the electrolytic grinding composite processing head;

[0029] Figure 4 It is a schematic diagram of the processing results of the air film circular hole and the distribution of the surface remelting layer in the EDM forming results of a single air film hole;

[0030] Figure 5 It is a schematic diagram of the processing results of the air film special-shaped hole and the distribution of the surface remelting layer in the EDM forming results of a single air film hole;

[0031] Figure 6 Schematic diagram of the process of removing the remelted layer by composite machining of air film circular hole electrolytic grinding;

[0032] Figure 7 It is a schematic diagram of the process of removing the remelting layer on the surface of the diffusion structure section during the process of removing the remelting layer by the composite processing of the air film special-shaped hole electrolytic grinding;

[0033] Figure 8 Schematic diagram of the process of removing the remelted layer on the surface of the straight hole structure section during the process of removing the remelted layer by the composite machining of air film special-shaped holes with electrolytic grinding. DETAILED DESCRIPTION

[0034] The present invention discloses a method for making holes in turbine blades. Those skilled in the art can refer to the content of this article and appropriately improve the process parameters to achieve the desired effect. 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 the present invention. The method and application of the present invention have been described through preferred embodiments, and relevant personnel can obviously modify or appropriately change and combine the method and application of this article without departing from the content, spirit and scope of the present invention to realize and apply the technology of the present invention.

[0035] The method for making holes in turbine blades provided by the present invention mainly includes an electrospark forming process for air film holes and an electrolytic grinding composite process for removing the remelting layer. Figure 2 As shown, Figure 2 The figure is a schematic flow chart of a method for making holes in turbine blades according to an embodiment of the present invention.

[0036] In this embodiment, the electrolytic grinding composite processing head is composed of a copper substrate, a bronze binder, and CBN abrasive particles. The outer diameter of the functional structure of the electrolytic grinding composite processing head is 0.38 mm. The abrasive particles are distributed on the side wall of the electrolytic grinding composite processing head in a sparse and random distribution manner. Figure 3 As shown, Figure 3 It is a schematic diagram of the structure of an electrolytic grinding composite processing head, wherein 2 is an electrolytic grinding composite processing head, 21 is an electrolytic grinding composite processing head substrate, 22 is a binder between the electrolytic grinding composite processing head substrate and abrasive particles, and 23 is an electrolytic grinding composite processing head abrasive particles.

[0037] The present invention will be further described below in conjunction with embodiments:

[0038] Example 1

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

[0040] According to the spatial position and shape of the air film holes to be processed on the turbine blade, the processing sequence of the air film holes and the control program for each air film hole processing are planned, and the positioning clamping is achieved through the blade tenon. The hollow electrode wire with an outer diameter of 0.38 mm is clamped by the EDM composite function spindle head, and the hole to be processed is adjusted to the workstation through the five-axis system, and the air film hole processing control program is started, including motion unit control, EDM power supply control, flushing system control, processing process detection and recognition and feedback control, etc. The hollow electrode wire with an outer diameter of 0.38 mm is used to realize the forming processing of the round hole and dustpan hole (special-shaped hole) on the turbine blade, among which the diffusion hole section of the dustpan hole is realized by the scanning milling method; Figure 4 and Figure 5 As shown, Figure 4 Schematic diagram of the air film circular hole machining results and the distribution of the surface remelting layer in the EDM forming results of a single air film hole, where 1-turbine blade, 11-high temperature alloy substrate, 13-air film circular hole, 131-air film circular hole wall remelting layer. Figure 5 Schematic diagram of the machining results of the air film special-shaped hole and the distribution of the surface remelting layer in the EDM forming results of a single air film hole, where 1-turbine blade, 11-high-temperature alloy substrate, 12-special-shaped air film hole, 121-remelting layer of the hole wall of the diffusion hole section of the special-shaped air film hole, 122-remelting layer of the hole wall of the circular hole section of the special-shaped air film hole.

[0041] The EDM parameters in this embodiment are: the peak voltage of the pulse power supply is 100 V, the pulse width is 4 μs, the pulse interval is 12 μs, and the electrode rotation speed is 200 r / min. The inner diameter of the processed circular hole is 0.46 mm, and the average remelting layer thickness is 13 μm. With the high-frequency narrow pulse width pulse power supply and the optimized EDM process, the remelting layer on the surface of the air film circular hole and the air film special-shaped hole can be reduced to about 10 μm, and the thickness of the remelting layer is uniform.

[0042] After the forming process of the air film hole is completed, the EDM spindle head is switched to the electrolytic grinding composite processing head. According to the spatial position and shape of the air film hole on the turbine blade, the processing control program for removing the remelted layer by electrolytic grinding composite processing of each air film hole is planned, including motion unit control, electrolytic processing power supply control, flushing system control, processing process detection and recognition and feedback control, etc. The remelted layer of the expected thickness is removed by the electrolytic grinding composite processing method, and the electrolytic grinding and polishing of the inner wall of the air film hole is achieved.

[0043] Among them, to remove the remelted layer of the air film circular hole, firstly, according to the spatial position of the air film hole to be processed 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 processed hole, and through the hole shape and position model calculation, the end of the electrolytic grinding composite machining head is slightly extended out of the hole, that is, when the electrolytic grinding composite machining head rotates, the electrolytic grinding composite machining can act on all positions of the inner wall of the hole. By using optimized electrolyte composition, electrolytic machining power supply parameters, and electrolytic grinding composite machining action time, the remelted layer on the surface of the air film circular hole is removed to achieve zero remelted layer. Figure 6 As shown, Figure 6 Schematic diagram of the process of removing the remelted layer by composite machining of air film circular hole electrolytic grinding, where 1 is the turbine blade and 3 is the working fluid.

[0044] The removal of the remelted layer of the special-shaped hole includes the removal of the remelted layer of the diffusion hole section and the removal of the remelted layer of the straight hole section. In the removal of the remelted layer of the diffusion hole section, firstly, according to the spatial position and shape of the air film hole to be processed in the turbine blade, the initial relative position between the electrolytic grinding composite processing head and the turbine blade is set, so that the side wall of the electrolytic grinding composite processing head is parallel to and in contact with one side wall of the diffusion hole, and then the relative movement path between the electrolytic grinding composite processing head and the turbine blade is planned according to the three-dimensional model of the special-shaped hole, so that the electrolytic grinding composite processing head moves around the side wall of the diffusion structure for one or several circles, and the remelted layer on the surface of the diffusion structure section of the air film hole is removed by the electrolytic grinding composite processing action, and the zero remelted layer of the diffusion hole section is achieved by optimizing the movement path, electrolyte composition and electrolytic processing power supply parameters. Figure 7 As shown, Figure 7 Schematic diagram of the process of removing the remelted layer on the surface of the diffusion structure section during the process of removing the remelted layer by the composite machining of air film special-shaped holes with electrolytic grinding.

[0045] In the removal of the remelted layer in the straight hole section, firstly, according to the spatial position and shape of the air film hole to be processed in 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 processed hole, and through the hole shape model calculation, the end of the electrolytic grinding composite machining head is slightly extended out of the hole, that is, when the electrolytic grinding composite machining head rotates, the electrolytic grinding composite machining can act on all positions of the inner wall of the hole. By using 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 air film hole is removed to achieve zero remelted layer in the straight hole section. Figure 8 As shown, Figure 8 Schematic diagram of the process of removing the remelted layer on the surface of the straight hole structure section during the process of removing the remelted layer by the composite machining of air film special-shaped holes with electrolytic grinding.

[0046] The electrolytic grinding composite processing parameters in this embodiment 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 processing 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 remelting layer of the air film circular hole is removed by electrolytic grinding composite processing for 10 s. In the process of removing the remelting layer of the diffusion hole section, the feed speed of the electrolytic grinding composite processing of the dustpan hole is 0.4 mm / s, and the circumferential feeding around the diffusion hole is 2 weeks. In the process of removing the remelting layer of the straight hole section, the electrolytic grinding composite processing is continued for 10 s to remove the remelting layer.

[0047] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for making holes in turbine blades, characterized in that: The following steps are involved: S1) performing electrospark machining on the turbine blade to be processed to form a hole, thereby forming an air film hole on the turbine blade to be processed; S2) using an electrolytic grinding composite processing head to electrolytically grind the air film holes on the turbine blade to be processed obtained in step S1); The electrolytic grinding process is specifically as follows: using the electrolytic grinding composite processing head as a negative electrode and the turbine blade to be processed as a positive electrode, electrolyzing and grinding the air film holes on the turbine blade to be processed in an electrolyte at the same time; The peak voltage of the electrolytic pulse power supply 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 hole is a circular air film hole; In step S2), the electrolytic grinding composite processing head passes through and extends out of the air film hole and surrounds the inner wall of the air film hole to perform electrolytic grinding processing.

3. The hole making method according to claim 1, characterized in that: In step S1), the air film hole is an air film irregular hole, and the air film irregular hole is composed of a diffusion hole segment and a straight hole segment; In step S2), the electrolytic grinding composite processing head is placed around the inner wall of the diffusion hole section of the air film hole for electrolytic grinding; the electrolytic grinding composite processing head passes through and extends out of the straight hole section of the air film hole and places around the inner wall of the straight hole section for electrolytic grinding.

4. The hole making method according to claim 1, characterized in that: The ratio of the outer diameter of the electrolytic grinding composite processing 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 parameter conditions of the electrospark machining are: 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~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 in step S1) is a circular air film hole, the electrolytic grinding time in step S2) is 5 s to 10 s; If the air film hole in step S1) is an air film irregular hole, then in step S2), an electrolytic grinding composite processing head is used to surround the inner wall of the diffusion hole segment of the air film hole at a feed speed of 0.3 mm / s~0.5 mm / s for 1~3 cycles for electrolytic grinding, and the electrolytic grinding composite processing head passes through and extends out of the straight hole segment of the air film hole and surrounds the inner wall of the straight hole segment for electrolytic grinding for 5 s~10 s.

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

10. The hole making method according to claim 9, characterized in that: The abrasive particles are randomly and sparsely distributed.

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