Chemical-physical coupling polishing medium, method and device for fine and complex internal flow channels

Abstract

The present invention relates to the technical field of precision machining of parts, and discloses a chemical-physical coupling polishing medium, method, and device for fine and complex internal flow channels. By adding a chemical polishing liquid to a water-based two-phase flow polishing medium, utilizing chemical polishing components to dissolve and soften the metal surface, and synchronously coordinating the physical polishing of abrasive particles in the two-phase flow, innovative chemical-physical coupling polishing can reduce the driving pressure and flow rate required for the composite polishing liquid. By establishing a quantitative relationship and control means between the static chemical removal rate and the chemical-physical coupling removal rate in the chemical-physical coupling polishing method for complex and fine internal flow channels, it is ensured that the composite polishing liquid can achieve the optimal polishing effect that meets the designed roughness of the internal flow channel; and improves the existing technology that uses only high-speed water-based two-phase flow polishing medium technology to polish and additively manufacture fine and complex internal flow channels, which can easily produce non-uniform polishing at the channel bends, and even dimensional deviations and damage due to excessive driving pressure and flow rate.

Description

Technical Field

[0001] The invention relates to the technical field of precision machining of parts, and discloses a chemical-physical coupling polishing medium, method and device for a fine and complex internal flow channel. Background Art

[0002] Parts with complex, microscopic internal flow path structures are widely used in aerospace, shipbuilding, nuclear, automotive, and mold manufacturing industries. Parts related to fluid power systems, in particular, often feature complex internal structures such as microscopic flow paths, deep orifices, and interconnected microscopic flow paths and deep orifices. These structures facilitate the transport, exchange, and application of fluid pressure. Examples include fuel nozzles, heat exchangers, hydraulic components, and oil control throttles in various aviation, aerospace, shipbuilding, and automotive engines. Technologies capable of processing these microscopic, complex internal flow paths include precision machining, femtosecond / water-guided / long-pulse laser machining, electrospark machining, and additive manufacturing (3D printing).

[0003] Additive manufacturing (3D printing) is a technology that discretizes complex three-dimensional structural part models into two-dimensional structures and then forms them layer by layer. It enables the integrated molding of complex, microscopic parts with complex internal flow channels, and is therefore increasingly used in industries such as aerospace, automotive, and mold manufacturing. However, due to the inherent process characteristics of additive manufacturing, such as temperature gradients and layer-by-layer molding, the surface of the part's internal flow channels may contain semi-sintered or bonded powder particles and a surface "step" effect. This rough internal flow channel can cause turbulence and eddy currents during fluid movement, and a sharp increase in fluid resistance along the flow path, even causing loss of fluid control and vibration that reduces the service life of the part. Rough surfaces can also cause a large number of cavitation bubbles to form in the fluid, affecting combustion and hydraulic dynamics, and even causing cavitation corrosion. Therefore, the internal flow channels of most additively manufactured parts require finishing before they can be used in actual engineering applications. Finishing technology for complex internal flow channels in additive manufacturing has become an internationally recognized industry challenge.

[0004] Patent CN114734365B proposes a method for finishing fine, complex internal flow channel surfaces using a water-based two-phase flow polishing medium. This method uses hydraulic thrust to drive a water-based polishing medium with a viscosity of less than 1000 cP through the fine internal flow channel at a flow rate of >5 m / s. The abrasive particles, along with the high-speed motion of the water-based fluid, produce high-speed, high-frequency micro-cutting, ultimately achieving efficient polishing of fine, complex internal flow channels with a diameter ≤3 mm and an aspect ratio ≥50:1. However, during high-speed polishing using the water-based two-phase flow polishing medium, the inertial centrifugal force acting upon the polishing medium as it passes through a turn in the internal flow channel can easily lead to uneven radial distribution of abrasive particles along the turn. Specifically, the number of abrasive particles near the outer wall of the turn is significantly greater than that near the inner wall. This phenomenon is exacerbated by higher polishing medium flow rates and smaller turn angles / curve radii, resulting in uneven polishing of the inner and outer sides of the turn. In some cases, the outer wall may even be over-polished, out-of-tolerance, or even damaged due to the dense impact of abrasive particles.

[0005] Patent CN114734365B describes a water-based two-phase flow technology for finishing additive manufacturing of fine and complex internal flow channels. This technology can improve problems such as uneven polishing at channel bends, and even dimensional deviations and damage, by reducing the polishing medium driving pressure and flow rate. However, further engineering tests have shown that reducing the polishing medium driving pressure and flow rate significantly reduces the high-speed micro-cutting effect and polishing efficiency of the high-speed water-based two-phase flow. It can even make certain hard alloys such as CoCoMo high-temperature alloys impossible to polish due to insufficient abrasive movement speed and cutting force. Summary of the Invention

[0006] The purpose of the present invention is to provide a chemically and physically coupled polishing medium, method and device for fine and complex internal flow channels, which can improve the problems of uneven polishing at the channel bends, even dimensional deviations and damage, caused by excessively high driving pressure and flow rate when finishing and additively manufacturing fine and complex internal flow channels in the existing technology using only high-speed water-based two-phase flow polishing medium technology.

[0007] In order to achieve the above technical effects, the technical solution adopted by the present invention is:

[0008] A chemical-physical coupled polishing medium with a fine and complex internal flow channel, the chemical-physical coupled polishing medium comprising a water-based two-phase flow polishing medium and a chemical polishing liquid, wherein the usage ratio of the water-based two-phase flow polishing medium and the chemical polishing liquid in the chemical-physical coupled polishing medium is arbitrary.

[0009] Furthermore, the dynamic chemical removal rate of the chemical polishing liquid flowing in the micro-channel of the part to be polished is the static chemical removal rate v of the planar structure part of the same material with the micro-channel immersed in the chemical polishing liquid. c1 12.5% ​​to 25%.

[0010] Furthermore, the chemical polishing liquid has a static chemical removal rate of no less than 0.01 μm / s on the material of the part to be polished.

[0011] To achieve the above technical effects, the present invention also provides a chemical-physical coupled polishing method for fine and complex internal flow channels, comprising:

[0012] A water-based two-phase flow polishing medium and a chemical polishing liquid are obtained respectively;

[0013] The test piece is immersed in the chemical polishing liquid. The test piece is a planar structural part made of the same material as the fine inner flow channel. The static chemical removal rate v of the part material in the chemical polishing liquid is obtained based on the measured value of the planar thickness change of the test piece per unit time. c1 ;

[0014] Adding the chemical polishing liquid in different dosage ratios to the water-based two-phase flow polishing medium to form composite polishing liquids in different dosage ratios;

[0015] Under preset polishing parameter conditions, different amounts of composite polishing liquid are respectively input into the fine inner flow channel of the corresponding part sample to be polished to perform a preset polishing test, and the initial flow value φ0 of the composite polishing liquid in the inner flow channel under the preset polishing parameter conditions and the instantaneous flow value φ1 of the composite polishing liquid at the completion of the preset polishing test are obtained by a flow meter; the preset polishing parameter conditions include the polishing experiment time t, the constant flow rate v0 of the composite polishing liquid, and the preset driving pressure of the composite polishing liquid;

[0016] According to the initial flow value of the composite polishing liquid under the preset polishing parameter conditions Preset instantaneous flow rate of composite polishing fluid when polishing test is completed The chemical-physical coupling removal rate v of each set of composite polishing liquids under the preset driving pressure is analyzed;

[0017] By regulating the driving pressure and temperature of the composite polishing liquid, the chemical-physical coupling removal rate v is obtained as the static chemical polishing removal rate v of the part material. c1 The chemical-physical coupling polishing of the fine and complex internal flow channel is performed under the standard driving pressure and temperature corresponding to the composite polishing liquid of 25% to 50%.

[0018] Furthermore, measured by mass concentration, the water-based two-phase flow polishing medium includes 8 to 80 g / L of solid abrasive, 3 to 8 g / L of viscosity enhancer, 6 to 12 g / L of defoaming agent; 0.5 to 5 g / L of lubricant, 10 to 20 g / L of dispersant, and 0.5 to 1 g / L of antifreeze; the chemical polishing liquid includes: 1 to 5 ml of hydrochloric acid solution, 1 to 3 ml of nitric acid solution, 10 to 25 ml of H2O, 10 to 20 g of FeCl3, 1 to 3 g of EDTA, and 2 to 5 g of Na2MoO4; the HCl content in the hydrochloric acid solution is 30% to 37%, and the HNO3 content in the nitric acid solution is 40% to 70%.

[0019] Furthermore, the chemical-physical coupling removal rate of the composite polishing liquid under a preset driving pressure is Among them is The initial flow rate value of the composite polishing liquid, is the instantaneous flow rate value of the composite polishing liquid when the polishing test is completed, t is the polishing experiment time in the preset polishing parameter conditions, and v0 is the constant flow rate of the composite polishing liquid.

[0020] Furthermore, the preset driving pressure is reduced by 50% or more compared with the traditional driving pressure, which is the driving pressure required to achieve the designed roughness of the flow channel in the part to be polished when polishing using the water-based two-phase flow polishing medium alone.

[0021] In order to achieve the above-mentioned technical effects, the present invention also provides a chemical-physical coupled polishing device for fine and complex internal flow channels, which is used to implement the chemical-physical coupled polishing method for fine internal flow channels, including a cylinder body for accommodating the composite polishing liquid, the inner wall of the cylinder body is inlaid with an inner liner made of a polymer material, and the polymer material includes one or more combinations of polytetrafluoroethylene, polyethylene, polypropylene, nylon, and polyetheretherketone; a piston for driving the composite polishing liquid is provided in the cylinder body, and the piston is made of aluminum alloy treated by micro-arc oxidation surface ceramicization; the discharge end of the cylinder body is connected to the fine internal flow channel of the part to be polished through a material guide pipe.

[0022] Furthermore, during the micro-arc oxidation surface ceramic treatment of the piston, the electrical parameters for the growth of the micro-arc alumina ceramic layer are a frequency of 1000-2000 Hz, a pulse width of 10-100 μm, a treatment time of 3-20 min, a thickness of the alumina ceramic layer of approximately 80-100 μm, and a bonding strength between the alumina ceramic layer and the aluminum alloy substrate greater than 120 MPa.

[0023] Furthermore, a sealing ring is provided between the piston and the inner wall of the inner liner of the cylinder body, and the outer diameter of the sealing ring is 1.003 to 1.02 times the inner diameter of the inner liner of the cylinder body.

[0024] Furthermore, the method of inserting the polymer material liner into the material cylinder adopts the hot pressing method, firstly heating the polymer material liner to above its glass transition temperature, then placing the heated polymer material liner into the cylinder body, and using a pressurized mold to apply a pressure of 2 to 6 MPa, so that the polymer material liner fits with the inner wall of the material cylinder under pressure and cooling.

[0025] Compared with the existing technology, the beneficial effects of the present invention are: the present invention adds a certain proportion of chemical polishing liquid to the water-based two-phase flow polishing medium, dissolves and softens the metal surface through the chemical polishing components in the water-based two-phase flow polishing medium, and synchronizes the physical polishing of the abrasive particles in the two-phase flow, thereby innovating the chemical-physical coupling polishing method of chemical components and physical components. On the one hand, it can significantly enhance the removal and polishing efficiency of the water-based two-phase flow polishing medium; on the other hand, it can reduce the driving pressure and flow rate required for the composite polishing liquid while achieving the same polishing effect as the water-based two-phase flow polishing medium without adding chemical polishing liquid.

[0026] 2. The static chemical polishing removal rate v in the chemical-physical coupling polishing method of the complex micro-channel is established in the present invention. c1 The quantitative relationship between the removal rate v and the chemical-physical coupling removal rate is established, and the quantitative relationship is ensured by regulating the driving pressure and the temperature of the composite polishing liquid. Ultimately, at the standard driving pressure and temperature, it is ensured that the composite polishing liquid can achieve the best polishing effect that meets the designed roughness of the inner flow channel, achieving the target requirements of roughness Ra < 1.6μm and turning deformation controlled within 0.1mm.

[0027] Improve the existing technology that uses high-speed water-based two-phase flow polishing medium technology alone to polish the fine and complex internal flow channels in additive manufacturing, which is prone to uneven polishing at the channel bends, and even dimensional deviations and damage due to excessive driving pressure and flow rate. The existing technology uses high-speed water-based two-phase flow alone to achieve a roughness Ra < 1.6μm and control the turning deformation within 0.25mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Flow chart of the chemical-physical coupled polishing method for the fine and complex internal flow channel in Example 1 or 2;

[0029] Figure 2 This is a schematic cross-sectional view of a two-dimensional additively manufactured CoCoMo high-temperature alloy inner flow channel sample with a turning structure after polishing using the composite polishing liquid in Example 2. DETAILED DESCRIPTION

[0030] The present invention will be described in further detail below with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the present invention to the following embodiments, as all technologies implemented based on the present invention fall within the scope of the present invention.

[0031] Example 1

[0032] See also Figure 1 , a chemical-physical coupled polishing method for fine and complex internal flow channels, comprising:

[0033] A water-based two-phase flow polishing medium and a chemical polishing liquid are obtained respectively;

[0034] The test piece is immersed in the chemical polishing liquid. The test piece is a planar structural part made of the same material as the fine inner flow channel. The static chemical removal rate v of the part material immersed in the chemical polishing liquid is obtained based on the measured value of the planar thickness change of the test piece per unit time. c1 ;

[0035] Adding the chemical polishing liquid in different dosage ratios to the water-based two-phase flow polishing medium to form composite polishing liquids in different dosage ratios;

[0036] Under preset polishing parameter conditions, different amounts of composite polishing liquid are respectively input into the fine inner flow channel of the corresponding part sample to be polished to perform a preset polishing test, and the initial flow value φ0 of the composite polishing liquid in the inner flow channel under the preset polishing parameter conditions and the instantaneous flow value φ1 of the composite polishing liquid at the completion of the preset polishing test are obtained by a flow meter; the preset polishing parameter conditions include the polishing experiment time t, the constant flow rate v0 of the composite polishing liquid, and the preset driving pressure of the composite polishing liquid;

[0037] According to the initial flow value φ0 of the composite polishing liquid under the preset polishing parameter conditions and the instantaneous flow value φ1 of the composite polishing liquid when the preset polishing test is completed, the chemical-physical coupling removal rate v of each group of composite polishing liquids under the preset driving pressure is analyzed;

[0038] Select the chemical-physical coupling removal rate v as the static chemical polishing removal rate v of the part material c1 The composite polishing liquid with a concentration of 25% to 50% is used to perform chemical-physical coupled polishing of the fine and complex internal flow channel under the preset polishing parameter conditions.

[0039] In this embodiment, a certain proportion of chemical polishing liquid is added to the water-based two-phase flow polishing medium. The chemical polishing components in the water-based two-phase flow polishing medium dissolve and soften the metal surface, and the abrasive particles in the two-phase flow perform physical polishing in a synchronous and coordinated manner. This innovative chemical-physical coupling polishing method of the chemical and physical components can significantly enhance the removal and polishing efficiency of the water-based two-phase flow polishing medium. On the other hand, while achieving the same polishing effect as the water-based two-phase flow polishing medium without the addition of chemical polishing liquid, the driving pressure and flow rate required for the composite polishing liquid can be reduced. This improves the existing technology that uses only high-speed water-based two-phase flow polishing medium technology to polish fine and complex internal flow channels in additive manufacturing, which can easily cause uneven polishing at channel bends, even dimensional deviations, and damage due to excessively high driving pressure and flow rate. This avoids the problem of significantly reducing the high-speed micro-cutting effect and polishing efficiency of the high-speed water-based two-phase flow due to reducing the driving pressure and flow rate of the high-speed water-based two-phase flow polishing medium, and even the inability to polish certain hardness alloys such as CoCoMo high-temperature alloys due to insufficient abrasive particle movement speed and cutting force.

[0040] It should be noted that if the driving pressure and flow rate of the composite polishing liquid are too low, the physical polishing efficiency of the abrasive particles will be too low, and the abrasive particles in the composite polishing liquid cannot fully remove the dissolved layer and softened layer produced by chemical polishing through physical means, but the polishing effect will be worse. If the driving pressure and flow rate of the composite polishing liquid are too high, it will not be able to effectively improve the finishing of the fine and complex internal flow channels of additive manufacturing. Due to the high driving pressure and flow rate, it is easy to produce non-uniform polishing at the initial additive manufacturing flow channel bends, and even dimensional deviations and damage. The dynamic flow chemical removal rate v of the composite polishing liquid in the fine internal flow channel is c2 The best polishing effect is achieved when the physical removal rate of the abrasive is equal to or comparable to that in the composite polishing fluid.

[0041] Therefore, this embodiment provides the relationship between the dynamic chemical polishing removal rate and the static chemical polishing removal rate of the chemical polishing liquid flowing in the fine inner flow channel based on engineering experience. c1 Determination of dynamic flow chemical removal rate v c2 The chemical-physical coupling removal rate is obtained by the preset polishing parameter test method. Based on the dynamic flow chemical removal rate v c2 Based on the specific relationship between the physical removal rate of abrasives in two-phase flow, a quantitative relationship between the static chemical polishing removal rate and the chemical-physical coupling removal rate in the chemical-physical coupling polishing method of complex and fine internal flow channels is established. On this basis, the ratio of driving pressure and polishing liquid temperature is regulated to ensure that the composite polishing liquid can achieve the optimal polishing effect that meets the designed roughness of the internal flow channel.

[0042] Based on the same inventive concept, this embodiment also provides a chemically and physically coupled polishing medium for a fine and complex internal flow channel, wherein the chemically and physically coupled polishing medium comprises a water-based two-phase flow polishing medium and a chemical polishing liquid, and the usage ratio of the water-based two-phase flow polishing medium and the chemical polishing liquid in the chemically and physically coupled polishing medium is an arbitrary ratio.

[0043] In practical engineering, the selection of the chemical polishing fluid added to the water-based two-phase flow polishing medium is crucial. It must effectively dissolve and soften the metal surface while avoiding excessive corrosion and damaging or rendering ineffective the thickeners, dispersants, suspending agents, and defoamers in the existing water-based two-phase flow polishing medium. In this embodiment, the water-based two-phase flow polishing medium includes, by mass concentration, 8-80 g / L of solid abrasive, 3-8 g / L of thickener, 6-12 g / L of defoamer, 0.5-5 g / L of lubricant, 10-20 g / L of dispersant, and 0.5-1 g / L of antifreeze. The chemical polishing fluid includes: 1-5 ml of hydrochloric acid solution, 1-3 ml of nitric acid solution, 10-25 ml of H₂O, 10-20 g of FeCl₃, 1-3 g of EDTA, and 2-5 g of Na₂MoO₄. The hydrochloric acid solution contains 30% to 37% HCl, and the nitric acid solution contains 40% to 70% HNO₃. The addition of the unique complexing agent EDTA forms a stable complex with metal ions, rapidly complexing the metal ions from the material surface to dissolve and soften the metal surface. This reduces the hydrochloric acid and nitric acid content in the chemical polishing solution. This reduction significantly mitigates the effects of strong acids on the deterioration and ineffectiveness of thickeners, defoamers, dispersants, and antifreeze agents in the water-based two-phase flow polishing medium. Furthermore, the addition of the chemical polishing solution accelerates the softening and dissolution of the metal surface in the inner flow channel. Therefore, the low-pressure, low-speed composite polishing medium can achieve the same excellent polishing effect as water-based two-phase flow polishing alone. Furthermore, in this embodiment, the addition of the chemical polishing solution to the water-based two-phase flow polishing medium accelerates the polishing process. The chemical softening and dissolution process prevents rust on the inner flow channel surface. Rust inhibitors can reduce the catalytic effect of the chemical polishing medium. Therefore, compared to conventional high-speed water-based two-phase flow polishing media, the new composite polishing solution eliminates the rust inhibitor. The raw materials and dosage of the composite polishing medium of this embodiment are reasonably configured to solve the difficult problems of component selection and reaction state control of the composite polishing liquid.

[0044] In this embodiment, according to the polishing experiment time t (10 to 30 min) and the constant flow rate v0 (3 m / s) of the composite polishing liquid in the preset polishing parameters, the formula Calculate the chemical-physical coupling removal rate v of the composite polishing liquid under the preset driving pressure. The chemical-physical coupling removal rate v is approximately the static chemical polishing removal rate v of the part material. c1The chemical-physical coupling polishing effect is best when the polishing temperature is 25% to 50%.

[0045] In this embodiment, the chemical-physical coupling removal rate includes two main parts: chemical polishing and physical polishing. During the chemical-physical coupling polishing process, the polishing effect is best when the physical removal rate and the chemical dynamic removal rate are equal or comparable. If the dynamic chemical removal rate is too fast, it will cause excessive corrosion on the surface of the material, resulting in defects such as deep pits and holes or the formation of a dense and strong oxide film. Physical polishing will find it difficult to remove the deep damage layer or dense and strong oxide film produced by chemical polishing, and the surface roughness of the inner flow channel will increase after chemical-physical coupling polishing. On the contrary, if the physical removal rate is too fast, chemical polishing will not have enough time to fully dissolve and soften the metal surface. Physical polishing will not be able to efficiently remove hard microscopic protrusions and effectively improve the roughness because the hardness of the material is difficult to reduce. Therefore, the chemical-physical coupling polishing effect is best when the dynamic chemical removal rate of the composite polishing liquid flowing through the fine inner flow channel accounts for 50% of the chemical-physical coupling removal rate. According to engineering experience, the dynamic removal rate of the chemical polishing liquid flowing through the fine inner flow channel is v c2 It is about 12.5% ​​to 25% of the static chemical removal rate of the planar structure parts of the same material with fine internal flow channels. Therefore, the chemical-physical coupling removal rate v is about the static chemical removal rate v of the part material. c1 The chemical-physical coupling polishing effect is best when the polishing temperature is 25% to 50%.

[0046] Based on the above reasons and conditions, the driving pressure is reduced by 50% or more compared with the traditional driving pressure. The traditional driving pressure is the driving pressure that enables the flow channel in the part to be polished to reach the designed roughness when polishing using the water-based two-phase flow polishing medium alone.

[0047] Based on the same inventive concept, this embodiment also provides a chemical-physical coupled polishing device for fine and complex internal flow channels, which is used to implement the chemical-physical coupled polishing method for fine internal flow channels, including a cylinder body for accommodating the composite polishing liquid, the inner wall of the cylinder body is inlaid with an inner liner made of a polymer material, and the polymer material includes one or more combinations of polytetrafluoroethylene, polyethylene, polypropylene, nylon, and polyetheretherketone; a piston for driving the composite polishing liquid is provided in the cylinder body, and the piston is made of aluminum alloy treated by micro-arc oxidation surface ceramicization; the discharge end of the cylinder body is connected to the fine internal flow channel of the part to be polished through a material guide pipe.

[0048] In this embodiment, a polymer liner is inserted into the cylinder body, tightly fitting it to the inner wall of the cylinder to prevent the chemical polishing liquid in the polishing medium from dissolving and corroding the cylinder wall. Polymer materials can be selected from polytetrafluoroethylene, ultra-high molecular weight polyethylene, polyvinylidene fluoride, perfluoroalkoxy resin, polyphenylene sulfide, etc. The polymer liner is inserted into the cylinder using a hot press method. The polymer liner is first heated to above its glass transition temperature (Tg). At this time, the polymer material transforms from a glassy state to a highly elastic state or a viscous flow state, becoming soft and having good fluidity. It is then placed into the cylinder body. A specially designed mold is used to apply a pressure of 2 to 6 MPa, so that the liner fully conforms to the inner wall of the cylinder under the action of pressure and cooling. Specifically, the shape of the mold matches the internal shape of the cylinder. The mold has an outer fixed part and an inner movable part. When the mold is placed on the liner and placed in the cylinder, the inner movable part is driven toward the outer part by a screw and gear. During the movement, the pressure generated by the outer layer causes the liner to adhere tightly to the inner wall of the cylinder. This mold structure can ensure the uniformity of pressure to a certain extent. During this process, the polymer material will cool and shrink and form a close bond with the cylinder wall, thus achieving the purpose of inlaying.

[0049] The chemical-physical coupled polishing device of the present invention solves the problem of corrosion damage to some components of equipment using water-based two-phase polishing media without chemical polishing components, caused by the addition of chemical polishing liquid to the water-based two-phase polishing media. It also avoids the problem of chemical polishing liquid dissolving the cylinder wall, which can reduce the tightness of the gap between the sealing piston and the cylinder wall, and even cause corrosion cracks on the cylinder surface, thereby reducing the sealing performance of the cylinder-piston system.

[0050] In this embodiment, during the micro-arc oxidation surface ceramic treatment of the piston, the electrical parameters for the growth of the micro-arc alumina ceramic layer are a frequency of 1000-2000 Hz, a pulse width of 10-100 μm, a treatment time of 3-20 min, a thickness of the alumina ceramic layer of approximately 80-100 μm, and a bonding strength between the alumina ceramic layer and the aluminum alloy substrate greater than 120 MPa.

[0051] The piston is made of aluminum alloy as its base material. Because of its high enough strength, it can withstand the high pressure and high-speed movement of high-speed water-based two-phase flow polishing media. The dense alumina ceramic layer with metallurgical bonding grown in situ on the surface of the aluminum alloy can improve its corrosion resistance to chemical polishing liquid in the composite polishing liquid. At the same time, the high hardness of the alumina ceramic layer can improve its resistance to abrasive friction and wear in water-based two-phase flow polishing media.

[0052] In this embodiment, a sealing ring is provided between the piston and the inner wall of the polymer liner of the cylinder body to enhance the sealing performance of the cylinder and ensure that the driving pressure meets the preset requirements. The outer diameter of the sealing ring is 1.003 to 1.02 times the inner diameter of the polymer liner. This allows the sealing ring around the piston to fit tightly against the inner wall of the polymer liner after extrusion deformation, further ensuring good sealing performance.

[0053] Example 2

[0054] See also Figure 1 and Figure 2 This example uses a two-dimensional CoCrMo high-temperature alloy internal flow channel sample with a curved structure as an example to illustrate the chemical-physical coupled polishing method for fine and complex internal flow channels of the present invention. The internal flow channel to be polished was produced using laser additive manufacturing technology. The structural parameters are: the micro-inner flow channel has an aperture D of approximately 2.5 mm, a total length of approximately 100 mm, an aspect ratio greater than 50:1, and includes a curved structure and an O-shaped bend. The channel is made of a high-temperature alloy, and the original roughness Ra of the internal flow channel is approximately 5.8 μm. The specific processing method is as follows:

[0055] Step 1: prepare a water-based two-phase flow polishing medium and a chemical polishing liquid respectively;

[0056] In this embodiment, the water-based two-phase flow polishing medium includes, by mass concentration, 40.2 g / L of solid abrasive, 5.1 g / L of tackifier, 6.0 g / L of defoamer, 3.0 g / L of lubricant, 15.5 g / L of dispersant, and 0.62 g / L of antifreeze.

[0057] The chemical polishing solution includes: 3.3 ml of hydrochloric acid solution, 2.6 ml of nitric acid solution, 20.9 ml of H2O, 12.7 g of FeCl3, 2.6 g of EDTA, and 2.9 g of Na2MoO4. The hydrochloric acid solution has an HCl content of 30% to 37%, and the nitric acid solution has an HNO3 content of 40% to 70%.

[0058] Step 2: Immerse the sample of the part to be polished in the chemical polishing solution and measure the static chemical polishing removal rate v of the part material. c1 ;

[0059] In this embodiment, a planar structural part made of the same material as the micro-inner flow channel part sample to be polished is immersed in the chemical polishing solution, and a micrometer is used to measure the thickness of the part plane. The static chemical polishing removal rate v of the part material is obtained based on the measured value of the change in the part plane thickness per unit time. c1 ; Different dosage ratios of chemical polishing liquid need to ensure the static chemical removal rate v of the part material c1 Not less than the lower limit of 0.01μm / s. The reason is that the static chemical removal rate vc1 Too low to achieve the dynamic flow chemical removal rate v of the composite polishing liquid in the fine inner flow channel c2 Equal or comparable to the physical removal rate of abrasive particles in two-phase flow.

[0060] In this embodiment, the static chemical polishing removal rate v of the high temperature alloy at different temperatures is measured. c1 See Table 1.

[0061] Table 1 Static chemical polishing removal rate v of high-temperature alloy materials at different solution temperatures c1 Data Sheet

[0062]

[0063] Step 3: Add the chemical polishing liquid in different dosage ratios to the water-based two-phase flow polishing medium, and slowly add the chemical polishing liquid to the water-based two-phase flow polishing medium while stirring at high speed to form a composite polishing liquid with different dosage ratios; the reason is that the EDTA in the chemical polishing liquid easily forms agglomerated complexes with the thickener, defoamer, dispersant, and antifreeze in the water-based two-phase flow polishing medium, thereby affecting its effect, so slow and high-speed stirring is required.

[0064] Step 4: Using the hydraulic drive assembly in Example 1, under the preset polishing parameters, input the composite polishing liquid with different dosage ratios into the fine flow channel of the corresponding part sample to be polished to perform a polishing test, and obtain the initial flow value of the composite polishing liquid under the preset polishing parameters. Preset instantaneous flow rate of composite polishing fluid when polishing test is completed The chemical-physical coupling removal rate v of each set of composite polishing liquids under the preset driving pressure is analyzed;

[0065] In this embodiment, during the chemical polishing liquid immersion and the composite polishing liquid polishing process, the temperature is controlled to be 45° C. and the driving pressure is 12 MPa.

[0066] Step 5: Obtain the initial flow value of the composite polishing liquid in the inner flow channel under the preset polishing parameter conditions through the flow meter Instantaneous flow rate value of composite polishing liquid when polishing test is completed According to the polishing experiment time t (10-30min) and the constant flow rate v0 (3m / s) of the composite polishing liquid in the preset polishing parameters, the formula The chemical-physical coupling removal rate v of the composite polishing liquid under the preset driving pressure is calculated.

[0067] Step 6: Regulate the temperature and driving pressure of the composite polishing liquid to achieve a chemical-physical coupling removal rate v of approximately the static chemical polishing removal rate v of the part material. c1The 25% to 50% requirement is met. When this requirement is met, the corresponding polishing liquid temperature and driving pressure are used as standard values ​​and the fine inner flow channels of the parts to be polished are polished.

[0068] like Figure 2 As shown, a cross-section of a 2D additively manufactured CoCrMo high-temperature alloy inner flow channel sample with a curved structure, polished using a chemical-physical composite polishing solution, reveals a smooth and bright surface with a flattening effect close to that of a machined surface and a significant finishing effect. Metallographic examination revealed no residue, embedded material, or under-sintering of the additively manufactured powder, achieving the target inner flow channel surface roughness Ra <1.6μm and a curvature within 0.08mm.

[0069] While water-based two-phase flow technology can improve problems such as uneven polishing at channel bends, and even dimensional deviations and damage, by reducing the polishing medium's driving pressure and flow rate when finishing fine, complex internal flow channels in additive manufacturing, further engineering tests have shown that reducing the polishing medium's driving pressure and flow rate significantly reduces the high-speed micro-cutting effect and polishing efficiency of the water-based two-phase flow. It can even render certain hardness alloys, such as CoCoMo superalloys, inoperable due to insufficient abrasive particle velocity and cutting force. The basic improvement proposed in the present invention is to add a certain proportion of chemical polishing liquid to the water-based two-phase flow polishing medium. The chemical polishing components in the two-phase flow polishing medium dissolve and soften the metal surface, significantly enhancing the physical removal rate and polishing effect of the abrasive particles on the simultaneously softened metal surface. In other words, the chemical and physical components in the polishing medium significantly enhance the removal and polishing efficiency of the water-based two-phase flow through a chemical-physical coupling mechanism. In other words, compared to water-based two-phase flow polishing medium without chemical components, the water-based two-phase flow polishing medium containing chemical components can achieve the same polishing effect with lower driving pressure and flow rate. The invention improves the high-speed water-based two-phase flow technology described in patent CN114734365B, which is prone to uneven polishing at the bends of the flow channel, and even dimensional deviations and damage, when finishing fine and complex internal flow channels in additive manufacturing due to excessively high driving pressure and flow rate. At the same time, it overcomes the problem that the high-speed micro-cutting effect and polishing efficiency of the original water-based two-phase flow polishing medium will be significantly reduced after reducing its driving pressure and flow rate.

[0070] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A chemical-physical coupled polishing method for fine and complex internal flow channels, characterized in that: include: A water-based two-phase flow polishing medium and a chemical polishing liquid are obtained respectively; The test piece is immersed in the chemical polishing liquid. The test piece is a planar structural part made of the same material as the fine inner flow channel. The static chemical removal rate of the part material in the chemical polishing liquid is obtained based on the measured value of the planar thickness change of the test piece per unit time. v c1 ; Adding the chemical polishing liquid in different dosage ratios to the water-based two-phase flow polishing medium to form composite polishing liquids in different dosage ratios; Under the preset polishing parameters, different amounts of composite polishing liquid are input into the micro-flow channel of the corresponding part sample to be polished for a preset polishing test. The initial flow value of the composite polishing liquid in the inner flow channel under the preset polishing parameters is obtained by the flow meter. φ 0. Preset the instantaneous flow value of the composite polishing liquid when the polishing test is completed φ 1; The preset polishing parameter conditions include polishing experiment time t , constant flow rate of composite polishing liquid v 0. Preset driving pressure of composite polishing liquid; According to the initial flow value of the composite polishing liquid under the preset polishing parameter conditions φ 0. Preset the instantaneous flow value of the composite polishing liquid when the polishing test is completed φ 1. Analyze and obtain the chemical-physical coupling removal rate of each set of composite polishing liquids under the preset driving pressure , where φ 0 Initial flow value of composite polishing liquid, φ 1 is the instantaneous flow rate value of the composite polishing liquid when the polishing test is completed, t is the polishing experiment time in the preset polishing parameter conditions, v 0 is the constant flow rate of the composite polishing liquid; By regulating the driving pressure and temperature of the composite polishing liquid, the chemical-physical coupling removal rate is obtained. v The static chemical polishing removal rate of the part material v c1 The standard driving pressure and temperature corresponding to the composite polishing liquid of 25% to 50% are used, and the chemical-physical coupling polishing of the fine and complex internal flow channel is performed under the standard driving pressure and temperature conditions.

2. The chemical-physical coupled polishing method for fine and complex internal flow channels according to claim 1, characterized in that: Measured by mass concentration, the water-based two-phase flow polishing medium includes 8 to 80 g / L of solid abrasive, 3 to 8 g / L of viscosity enhancer, 6 to 12 g / L of defoaming agent; 0.5 to 5 g / L of lubricant, 10 to 20 g / L of dispersant, and 0.5 to 1 g / L of antifreeze; the chemical polishing liquid includes: 1 to 5 ml of hydrochloric acid solution, 1 to 3 ml of nitric acid solution, 10 to 25 ml of H2O, 10 to 20 g of FeCl3, 1 to 3 g of EDTA, and 2 to 5 g of Na2MoO4; the HCl content in the hydrochloric acid solution is 30% to 37%, and the HNO3 content in the nitric acid solution is 40% to 70%.

3. The chemical-physical coupled polishing method for fine and complex internal flow channels according to claim 1, characterized in that: The preset driving pressure is 50% or more lower than the conventional driving pressure, which is the driving pressure required to achieve the designed roughness of the flow channel in the part to be polished when the water-based two-phase flow polishing medium is used alone for polishing.

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