A titanium alloy mixed gas atomization discharge ablation processing method combining positive and negative polarity and its processed parts

Abstract

The embodiment of the present application relates to a titanium alloy mixed gas atomization discharge ablation processing method combining positive and negative polarity, which belongs to the technical field of titanium alloy material processing. The embodiment of the present application aims to solve the technical problem that the discharge ablation processing in the prior art generally adopts the negative polarity processing of the tool electrode, and the surface of the workpiece after this efficient processing is relatively rough, which is not conducive to the subsequent cutting and finishing process. The processing method of the embodiment of the present application includes the following steps: S1, preparation stage: first, two mixed gases with an oxygen concentration of ≥40% and an oxygen concentration of ≤22% are prepared respectively, and mixed with the working fluid to form two mixed gas atomization media, which are sent into the inter-electrode discharge gap; S2, rough processing stage: the negative polarity of the tool electrode is used to perform discharge ablation processing on the titanium alloy, and a certain processing allowance is reserved; S3, finishing stage: the positive polarity of the tool electrode is used to perform discharge processing on the surface of the titanium alloy. The processing method provided by the embodiment of the present application can obtain titanium alloy parts with high-quality surfaces.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of titanium alloy material processing, and in particular to a titanium alloy mixed gas atomization discharge ablation processing method combining positive and negative polarity and a processed part thereof. Background Art

[0002] Titanium is a new metal whose properties are dependent on the levels of impurities such as carbon, nitrogen, hydrogen, and oxygen. The purest form of titanium iodide contains no more than 0.1% impurities, yet exhibits low strength and high plasticity. The density of titanium alloys is generally around 4.51 g / cm³, only 60% of that of steel. Some high-strength titanium alloys exceed the strength of many structural steel alloys. Therefore, titanium alloys have a strength-to-density ratio (strength / density) far exceeding that of other structural metals, enabling the manufacture of components with high unit strength, excellent rigidity, and lightweight properties. Aircraft engine components, frames, skins, fasteners, and landing gear all utilize titanium alloys. However, titanium and titanium alloys are typically difficult to machine due to their high specific strength, low elastic modulus, and poor thermal conductivity. Electrospark machining (EDM) utilizes the galvanic erosion phenomenon caused by pulsed spark discharges between the workpiece and tool to remove excess metal material, making it suitable for machining any difficult-to-cut conductive material.

[0003] There are numerous EDM methods for titanium alloys, with most currently focused on EDM using oil-based working fluids, gases, and gas-liquid two-phase media. Dry EDM and quasi-dry EDM use gas and gas-liquid mixed mist as the discharge medium, respectively. Dry EDM offers low electrode loss, no environmental pollution, and lower forces during machining. However, the limitations of dry EDM include slow machining speeds, difficulty machining thicker workpieces, and difficulty evacuating chips from the discharge gap, resulting in a high short-circuit rate and reduced machining stability. Furthermore, erosion products adhere to the workpiece surface, impacting machining quality. Quasi-dry EDM can utilize different liquid and gas mixtures depending on the application, and offers advantages such as fire hazards. Compared to dry EDM, it offers higher material removal rates and better shape accuracy. It also boasts faster speeds and a smaller discharge gap at low energy levels. However, increased energy leads to increased electrode loss, impacting machining efficiency. Furthermore, quasi-dry EDM has fewer adverse effects on human health and the environment.

[0004] In the prior art, a Chinese patent application numbered 201010544351.0 discloses a method for controlling the electric spark-induced combustion and explosion erosion of titanium or titanium alloys. This method involves intermittently introducing a gas that can generate intense oxidation heat and form a combustion and explosion effect with the titanium metal into the processing area during conventional electric spark machining of titanium or titanium alloys, so as to achieve the purpose of rapidly etching away a large amount of titanium and titanium alloy matrix materials. However, this machining method uses pure oxygen as the discharge medium, which is prone to excessive discharge ablation during the discharge machining process, forming larger ablation pits and affecting the accuracy of the discharge machining. In response to this phenomenon, a Chinese patent application numbered CN110605442B proposes a method for controlling the electric spark ablation of flammable and difficult-to-machine materials with an adjustable concentration of combustion-supporting gas. This method can avoid the occurrence of combustion and explosion or excessive ablation by adjusting the concentration of the oxygen medium when machining titanium alloy materials. However, after the discharge machining is completed, this machining method leaves a thick layer of oxidized melted solidified layer on the surface of the workpiece, which is not conducive to the machining of the workpiece surface quality integrity; furthermore, this machining method is similar to dry EDM, using pure gas medium as the discharge machining medium. According to relevant research literature, the performance of dry EDM is weaker than that of quasi-dry EDM to a certain extent, that is, its machining efficiency is weaker than that of quasi-dry EDM to a certain extent.

[0005] To improve material removal rates, EDM machining generally uses negative tool electrode polarity. However, this high-efficiency machining results in a relatively rough workpiece surface, hindering subsequent finishing processes. Therefore, improving the surface quality of EDM-processed workpieces remains a key issue in EDM machining. Summary of the Invention

[0006] In view of this, the embodiment of the present application provides a titanium alloy mixed gas atomization discharge ablation processing method combining positive and negative polarity and its processed parts. This processing method not only has the advantage of quasi-dry EDM to improve the dry EDM effect, but also has a higher processing efficiency than the discharge ablation processing of pure gas medium. It can also achieve thinning or even removal of the oxidized molten solidified layer to obtain titanium alloy parts with high-quality surfaces, so as to overcome the shortcomings of the above-mentioned existing technologies.

[0007] A first aspect of the present application provides a method for atomizing and ablation machining of a titanium alloy using a mixed gas atomization process with positive and negative polarity, comprising the following steps:

[0008] S1. Preparation stage: First, two mixed gases with an oxygen concentration of ≥40% and an oxygen concentration of ≤22% are prepared respectively, and then the two mixed gases are mixed with working fluids to form two mixed gas atomizing media, and then the two mixed gas atomizing media are respectively sent into the inter-electrode discharge gap through the hollow electrodes;

[0009] S2, rough machining stage: using a certain discharge energy, a mixed gas atomizing medium with an oxygen concentration of ≥40%, and a negative polarity of a tool electrode to perform discharge ablation machining on the titanium alloy, and reserving a certain machining allowance to obtain a rough-machined titanium alloy;

[0010] S3, finishing stage: using a certain discharge energy, a mixed gas atomizing medium with an oxygen concentration of ≤22%, and a positive polarity of a tool electrode to discharge machine the surface of the rough-machined titanium alloy to obtain a titanium alloy part with high surface quality.

[0011] The machining method of the embodiment of the present application adopts a machining method that combines positive and negative polarity, taking advantage of the polarity effect in electrical discharge machining (EDM), namely the characteristics of positive polarity for efficient etching and negative polarity for high-precision machining. First, negative polarity atomized ablation EDM with a tool electrode using high discharge energy and high oxygen concentration is used. While increasing the material removal rate, the high-pressure atomized medium can also effectively remove the ablation products and reduce the machining surface temperature. Then, positive polarity atomized EDM with a tool electrode using low discharge energy and low oxygen concentration is used to etch away the excess material, reducing the electrode wear rate while achieving a high-quality machined surface.

[0012] In some embodiments, which may include the above embodiments, the tool electrode is a non-rotating forming tool electrode / rotating forming tool electrode;

[0013] The negative polarity of the tool electrode is that the tool electrode is connected to the negative pole of the pulse power supply, and the titanium alloy is connected to the positive pole of the pulse power supply;

[0014] The positive polarity of the tool electrode is that the tool electrode is connected to the positive pole of the pulse power supply, and the titanium alloy is connected to the negative pole of the pulse power supply.

[0015] In some embodiments that may include the above embodiments, in step S2, the current of the discharge energy is 10-70A, the pulse width is 200-4000μs, and the machining allowance is 0.1-3mm; or in step S3, the current of the discharge energy is 0.1-10A, and the pulse width is 5-200μs.

[0016] In some embodiments that may include the above embodiments, the discharge ablation processing is performed by immersing the titanium alloy in the working fluid for processing, and the distance between the surface of the titanium alloy and the upper surface of the working fluid is ≥20 mm; or

[0017] The titanium alloy is processed without being immersed in the working fluid.

[0018] In some embodiments that may include the above embodiments, in step S1, the supply pressure of the mixed gas in the mixed gas atomizing medium is 0.05-5 MPa, and the supply pressure of the working fluid in the mixed gas atomizing medium is 0.05-5 MPa.

[0019] In some embodiments that may include the above embodiments, in step S1, the mixed gas is one or more of a mixed gas consisting of oxygen and nitrogen, a mixed gas consisting of oxygen and argon, a mixed gas consisting of oxygen and carbon dioxide, and a mixed gas consisting of oxygen, nitrogen and argon.

[0020] In some embodiments that may include the above embodiments, in step S1, the oxygen concentrations in the two mixed gases are 40%-98% and 1-22%, respectively.

[0021] In some embodiments that may include the above embodiments, the titanium alloy material is one or more of titanium, α-type titanium alloy, α+β-type titanium alloy, β-type titanium alloy, and titanium aluminum alloy.

[0022] In some embodiments that may include the above embodiments, in step S1, the working fluid is one or more of tap water, deionized water, ethylene glycol, spark oil, and bio-oil.

[0023] A second aspect of the embodiments of the present application further provides a titanium alloy workpiece, which is manufactured by using the titanium alloy mixed gas atomization discharge ablation processing method combining positive and negative polarity as described in any of the above items.

[0024] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0025] 1. The processing method of the embodiment of the present application forms an atomized medium by introducing a liquid medium into a mixed gas containing oxygen, which can significantly improve the inter-electrode discharge state and improve the discharge machining efficiency; the processing method of the embodiment of the present application can select different mixed media of mixed gas and liquid for different application objects.

[0026] 2. The machining method of the embodiment of the present application adopts a machining method that combines positive and negative polarity, taking advantage of the polarity effect in EDM, namely the characteristics of positive polarity for efficient etching and negative polarity for high-precision machining. First, high discharge energy and high oxygen concentration tool electrode negative polarity atomization EDM is used. While improving the material removal rate, the high-pressure atomized medium can also effectively remove the ablation products and reduce the machined surface temperature. Then, low discharge energy and low oxygen concentration tool electrode positive polarity atomization EDM is used to etch away the excess, reducing the electrode wear rate while obtaining a high-quality machined surface.

[0027] 3. The processing method of the embodiment of the present application utilizes the non-oxygen medium and liquid medium in the mixed gas to control the intensity of the oxidation and ablation reaction of the titanium alloy, suppress the explosion phenomenon that is very likely to occur during the ablation processing of the titanium alloy, and realize stable and efficient milling processing of the titanium alloy material.

[0028] 4. The tool electrode used in the processing method of the embodiment of the present application can be either a non-rotating forming tool electrode or a rotating tool electrode, which is suitable for various processing forms such as turning, milling, drilling and forming, and is conducive to achieving the efficient and high-precision processing requirements of titanium alloy parts with different structural forms.

[0029] 5. The processing method of the embodiment of the present application carries out rough machining and fine machining in one process, which not only shortens the tool setting time and the time for clamping the workpiece and the electrode, but also can realize different proportions of machining efficiency and machining quality by flexibly changing the machining parameters and the positive polarity machining allowance. It is universal and can be widely used in the high-quality machining of titanium alloy materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A schematic flow chart of the positive and negative polarity combined titanium alloy mixed gas atomization discharge ablation processing method provided in an embodiment of the present application;

[0032] Figure 2 (a) is a schematic diagram of the atomized discharge ablation milling process of the titanium alloy workpiece with the negative polarity of the tool electrode in step S2. Figure 2 (b) is a schematic diagram of the atomized discharge ablation milling process of the titanium alloy workpiece with the positive polarity of the tool electrode in step S3;

[0033] Figure 3 The figure shows the comparison of material removal rate (MRR) and relative electrode loss (TWR) of two machining methods: mixed gas positive polarity machining and air positive polarity machining.

[0034] Figure 4 This is a comparison chart of the results of positive polarity mixed gas atomization EDM machining and positive polarity air atomization EDM machining;

[0035] Figure 5 This is a comparison chart of the finishing results of negative polarity mixed gas and negative polarity air atomization discharge;

[0036] Figure 6 The figure compares the results of mixed gas atomization EDM machining with a combination of positive and negative polarity and mixed gas atomization EDM machining with a positive polarity. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0038] To improve material removal rates, existing EDM processes generally utilize negative tool electrode polarity. However, this high-efficiency machining results in a relatively rough workpiece surface, hindering subsequent finishing processes. Therefore, improving the surface quality of workpieces after EDM remains a key issue in EDM.

[0039] In order to solve the above technical problems, the present invention provides a method for atomizing and ablation machining of titanium alloy using a mixed gas with positive and negative polarity, comprising the following steps:

[0040] S1. Preparation stage: prepare two mixed gases with oxygen concentration ≥40% and oxygen concentration ≤22% respectively according to actual needs, then mix the two mixed gases with working fluid to form two mixed gas atomizing media, and then send the two mixed gas atomizing media into the inter-electrode discharge gap through the hollow electrodes respectively;

[0041] For example, the oxygen concentrations in the two mixed gases are 40%-98% and 1-22%, respectively. Preferably, a mixed gas with an oxygen concentration of 51%-95% and a mixed gas with an oxygen concentration of 1%-20% are used. Of course, the oxygen concentrations can be set to 75% and 15% respectively according to actual needs, and this application is not limited to this.

[0042] In a specific embodiment, the mixed gas is one or more of a mixed gas of oxygen and nitrogen, a mixed gas of oxygen and argon, a mixed gas of oxygen and carbon dioxide, or a mixed gas of oxygen, nitrogen, and argon. The selection can be made based on actual conditions and will not be further described in this application.

[0043] In a specific embodiment, the working fluid is one or more of tap water, deionized water, ethylene glycol, spark oil, and bio-oil. The selection can be made according to actual conditions, and this application will not elaborate on this.

[0044] In a specific embodiment, the supply pressure range of the mixed gas in the mixed gas atomizing medium is: 0.05-5MPa, for example: it can be 0.1MPa, 1MPa, 2MPa, 3MPa, 4.5MPa, etc., which is not limited in this application; the supply pressure range of the working fluid is 0.05-5MPa, for example: it can be 0.3MPa, 1.5MPa, 2.5MPa, 3.5MPa, 4MPa, etc., which is not limited in this application.

[0045] S2, rough processing stage: First, use a mixed gas atomization medium with large discharge energy and high oxygen concentration and a negative polarity of the tool electrode to perform efficient discharge ablation processing on the titanium alloy, and reserve a processing allowance of 0.1-3mm.

[0046] In a specific embodiment, the negative polarity processing parameters of the tool electrode are as follows: the current setting range is 10-70A, and the pulse width setting range is 200-4000μs; preferably, the negative polarity processing parameters of the tool electrode are as follows: the current setting range is 10-60A, and the pulse width setting range is 200-2000μs.

[0047] S3, finishing stage: Under the premise of the same material and form of electrode and the same machine tool as step S2, the titanium alloy surface with the reserved machining allowance in step S2 is subjected to discharge machining using a mixed gas atomizing medium with small discharge energy and low oxygen concentration and a positive polarity of the tool electrode, and finally the machining of the titanium alloy workpiece with high surface quality is completed to obtain a titanium alloy part with high surface quality.

[0048] In a specific embodiment, the tool electrode positive polarity processing parameters are as follows: the current setting range is 0.1-10A, and the pulse width setting range is 5-200μs; preferably, the tool electrode positive polarity processing parameters are as follows: the current setting range is 0.1-9A, and the pulse width setting range is 5-100μs.

[0049] In a specific embodiment, the tool electrode is a non-rotating forming tool electrode / a rotating forming tool electrode. The negative polarity of the tool electrode is when the tool electrode is connected to the negative electrode of the pulse power supply, and the titanium alloy is connected to the positive electrode of the pulse power supply. The positive polarity of the tool electrode is when the tool electrode is connected to the positive electrode of the pulse power supply, and the titanium alloy is connected to the negative electrode of the pulse power supply.

[0050] In a specific embodiment, the discharge ablation processing method is: immersing the titanium alloy in a working fluid for processing, and the distance between the surface of the titanium alloy and the upper surface of the working fluid is ≥20 mm; non-immersion discharge ablation processing can also be performed.

[0051] In a specific embodiment, the material of the titanium alloy workpiece is one or more of titanium, α-type titanium alloy, α+β-type titanium alloy, β-type titanium alloy, and titanium aluminum alloy.

[0052] The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination of the present application will be described in detail below through specific examples.

[0053] In the following examples and comparative examples, unless otherwise specified, all raw materials can be purchased commercially or prepared by conventional methods.

[0054] Example 1

[0055] A titanium alloy mixed gas atomization discharge ablation processing method using positive and negative polarity combined gas includes the following steps:

[0056] S1. Preparation stage: First, prepare two mixed gases consisting of oxygen and nitrogen with an oxygen concentration of 80% and an oxygen concentration of 21%, respectively. Then, mix the two mixed gases with tap water to form two mixed gas atomizing media. Then, the two mixed gas atomizing media are respectively sent into the inter-electrode discharge gap through the hollow electrodes;

[0057] S2, rough machining stage: using high discharge energy, a mixed gas atomization medium with an oxygen concentration of 80%, a rotating porous copper tool electrode with a diameter of 3 mm, and negative polarity to discharge ablate the α+β type titanium alloy, and reserving a machining allowance of 0.2 mm to obtain a rough-machined titanium alloy;

[0058] S3, finishing stage: Use small constant discharge energy, mixed gas atomization medium with an oxygen concentration of 21%, and positive polarity of the tool electrode to perform discharge machining on the surface of the rough-machined titanium alloy to obtain titanium alloy parts with high surface quality.

[0059] A processing groove with a size of 11mm*3mm*1mm, that is, a groove with a length of 11mm, a width of 3mm, and a depth of 1mm, is milled on the titanium alloy workpiece, and a layer-by-layer reciprocating milling method with a milling thickness of 0.2mm per layer is adopted; the base material used in this processing embodiment is TC4 titanium alloy (i.e., α+β type titanium alloy), with a size of 30mm×20mm×10mm, and a porous copper electrode with a diameter of 3mm is selected as the electrode. Non-immersion processing is adopted, and an electronic balance with a graduation value of 0.1mg is used to weigh the mass of the titanium alloy workpiece and the electrode before and after processing. The specific processing parameters are shown in Table 1.

[0060] Table 1

[0061]

[0062] Application Examples

[0063] First, a comparative experiment between positive polarity air atomization EDM and mixed gas positive polarity atomization EDM was conducted. A machining groove with a size of 11mm*3mm*1mm was milled on a titanium alloy workpiece, i.e., a groove with a length of 11mm, a width of 3mm, and a depth of 0.8mm. A layer-by-layer reciprocating milling method with a milling thickness of 0.2mm was adopted. The experimental parameters used the positive polarity machining parameters in Table 1, and the oxygen concentration of the mixed gas was 80%. In addition, the comparative example was carried out directly in an air atmosphere. Based on the comparative experimental results, the material removal rate (MRR) and relative electrode loss (TWR) of the two machining methods were calculated, as shown in Fig. Figure 3 As shown in the figure, the positive-polarity mixed gas atomization EDM method achieves a higher MRR while also achieving a lower TWR than the positive-polarity air atomization EDM method. However, both methods exhibit a wavy accumulation layer on the machined surface, resulting from the cooling of the molten material. This results in poor surface flatness, with an arithmetic mean roughness exceeding 15 μm.

[0064] Secondly, a comparative experiment was conducted on the negative polarity mixed gas and negative polarity air atomization discharge finishing processing. By reserving a machining allowance of 0.2mm on the surface of the titanium alloy workpiece after the above rough machining, the negative polarity machining parameters in Table 1 were used, and the oxygen concentration of the mixed gas was 80%. In addition, the comparative example was directly carried out in an air atmosphere. According to the comparative experimental results, it was found that Figure 5 As shown in the figure, the overcut of the air atomized EDM sample is smaller, and the surface flatness of the latter is better after measurement by a three-dimensional profilometer, and the arithmetic average roughness of the machined surface is about 10μm.

[0065] Then, a test was conducted combining positive-polarity mixed-gas atomized EDM with negative-polarity air atomized EDM finishing. Using the same electrode and machine tool, the specific machining parameters are shown in Table 1. First, the titanium alloy underwent positive-polarity mixed-gas atomized EDM (roughing stage), leaving a 0.2 mm machining allowance. The remaining machining allowance was then subjected to negative-polarity air atomized EDM (finishing stage), completing the finishing process after roughing. Figure 6 The following chart compares the results of EDM machining using a mixed gas atomization with positive and negative polarity and EDM machining using a mixed gas atomization with positive polarity. It can be seen that the surface machined using the positive polarity EDM machining method exhibits traces of molten metal flow and a bluish-purple oxide layer. The 3D contour image of the surface shows numerous depressions and peaks, resulting in poor surface flatness. Scan results indicate an arithmetic mean roughness of 16.4 μm. The surface of the workpiece machined using the positive and negative polarity EDM machining method exhibits a smooth surface with the silvery-white luster of the titanium alloy substrate. The 3D contour image shows only minor depressions and peaks, and the scan results indicate an arithmetic mean roughness of 9.5 μm.

[0066] Finally, in order to further confirm the advantages of the atomized discharge ablation processing method combining positive and negative polarity, the surface morphology and surface elements of the workpiece were analyzed using a scanning electron microscope and an EDS spectrometer. The workpiece was cut open using a wire cutting machine and the cross-sectional morphology of the recast layer was observed after processing. Figure 6 The comparison results show that due to the use of high discharge energy positive polarity atomized discharge ablation processing, a large number of micropores, microcracks and molten material flow marks are generated on the machined surface, and the thickness of the recast layer is relatively thick. The majority of oxides on the machined surface lead to an increase in the oxygen content and a decrease in the titanium content in the energy spectrum. However, after low discharge energy negative polarity atomized discharge finishing processing, the workpiece surface is smooth with only a few microcracks, the thickness of the recast layer is also greatly reduced, and the element proportion in the energy spectrum of the machined surface is lower than that of the former, while the titanium content is increased, and the oxides on the machined surface are reduced. The above comparison results show that the mixed gas atomized discharge ablation processing method combining positive and negative polarity is an efficient processing solution for titanium alloys, which effectively improves the processing capability of titanium alloy materials.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A titanium alloy mixed gas atomization discharge ablation processing method combining positive and negative polarity, characterized in that: The steps include: S1. Preparation stage: First, two mixed gases with an oxygen concentration of ≥40% and an oxygen concentration of ≤22% are prepared respectively, and then the two mixed gases are mixed with working fluids to form two mixed gas atomizing media, and then the two mixed gas atomizing media are respectively sent into the inter-electrode discharge gap through the hollow electrodes; S2, rough machining stage: using a certain discharge energy, the mixed gas atomizing medium with an oxygen concentration of ≥40%, and a negative polarity of the tool electrode to perform discharge ablation machining on the titanium alloy, and reserving a certain machining allowance to obtain a rough-machined titanium alloy; S3, finishing stage: using a certain discharge energy, a mixed gas atomizing medium with an oxygen concentration of ≤22%, and a positive polarity of a tool electrode to perform discharge machining on the surface of the rough-machined titanium alloy to obtain a titanium alloy part with high surface quality.

2. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: The tool electrode is a non-rotating forming tool electrode / rotating forming tool electrode; The negative polarity of the tool electrode is that the tool electrode is connected to the negative pole of the pulse power supply, and the titanium alloy is connected to the positive pole of the pulse power supply; The positive polarity of the tool electrode is that the tool electrode is connected to the positive pole of the pulse power supply, and the titanium alloy is connected to the negative pole of the pulse power supply.

3. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: In step S2, the current of the discharge energy is 10-70A, the pulse width is 200-4000μs, and the machining allowance is 0.1-3mm; or in step S3, the current of the discharge energy is 0.1-10A, and the pulse width is 5-200μs.

4. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: The discharge ablation processing method is: immersing the titanium alloy in the working liquid for processing, and the distance between the surface of the titanium alloy and the upper surface of the working liquid is ≥20mm; or The titanium alloy is processed without being immersed in the working fluid.

5. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: In step S1 , the supply pressure of the mixed gas in the mixed gas atomizing medium is 0.05-5 MPa, and the supply pressure of the working fluid in the mixed gas atomizing medium is 0.05-5 MPa.

6. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: In step S1, the mixed gas is one or more of a mixed gas consisting of oxygen and nitrogen, a mixed gas consisting of oxygen and argon, a mixed gas consisting of oxygen and carbon dioxide, and a mixed gas consisting of oxygen, nitrogen and argon.

7. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: In step S1, the oxygen concentrations in the two mixed gases are 40%-98% and 1-22% respectively.

8. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1 is characterized in that: The titanium alloy material is one or more of titanium, α-type titanium alloy, α+β-type titanium alloy, β-type titanium alloy, and titanium-aluminum alloy.

9. The titanium alloy mixed gas atomization discharge ablation processing method with positive and negative polarity combination according to claim 1, characterized in that: In step S1, the working fluid is one or more of tap water, deionized water, ethylene glycol, spark oil, and bio-oil.

10. A titanium alloy workpiece, characterized in that: The titanium alloy is manufactured by using the positive-negative polarity combined titanium alloy mixed gas atomization discharge ablation processing method described in any one of claims 1 to 9.

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