Chemical-physical coupling polishing medium, method and device for fine complex inner flow channel

Abstract

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 complex inner runner, chemical polishing liquid is added in a water-based two-phase flow polishing medium, chemical polishing components are utilized to dissolve and soften the metal surface, and abrasive particles in two-phase flow are physically polished synchronously and synergistically, so that the polishing effect of the fine complex inner runner is improved. Innovative chemical-physical coupling polishing can reduce the driving pressure and flow velocity required by the composite polishing solution. By establishing a quantitative relation and a regulation and control means between a static chemical removal rate and a chemical-physical coupling removal rate in a chemical-physical coupling polishing method of the complex micro inner flow channel, it is ensured that the composite polishing solution can achieve the optimal polishing effect meeting the design roughness of the inner flow channel; the problems that in the prior art, when a high-speed water-based two-phase flow polishing medium technology is singly adopted for finishing and additive manufacturing of a fine and complex inner flow channel, due to the too high driving pressure and flow speed, non-uniform polishing is easily generated at the turning position of the flow channel, and even size out-of-tolerance and damage occur are solved.

Description

Technical Field

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

[0002] Parts with fine and complex internal flow channel structures are widely used in aerospace, shipbuilding, nuclear, automobile, mold and other industrial fields. In particular, parts related to fluid power systems often have complex internal cavity structures such as fine flow channels, deep holes, and micro-flow channels and deep holes connected to each other, which play the role of transporting, exchanging or applying fluid pressure to fluids, such as aviation / aerospace / shipbuilding / automotive engine fuel nozzles, heat exchangers, hydraulic components, oil circuit control throttles, etc. Process technologies that can process fine and complex internal flow channels include precision machining, femtosecond / water-guided / long-pulse laser processing, 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 for layer-by-layer stacking and molding. It makes it possible to integrate complex, fine and complex internal flow channel parts, and is therefore increasingly used in aerospace, automotive, mold and other industrial fields. However, due to the temperature gradient and layer-by-layer molding process of additive manufacturing technology, semi-sintered or bonded powder particles and surface "step" effects exist on the surface of the internal flow channel of the parts. This rough internal flow channel will cause turbulence, eddy currents and a sharp increase in fluid resistance during fluid movement, and even cause fluid loss of control, vibration and reduce the service life of parts. Rough surfaces will also cause a large number of cavitation bubbles to be generated in the fluid, affecting combustion and hydraulics, and even causing cavitation corrosion. Therefore, the internal flow channels of most additive manufacturing parts need to be polished before they can be used in actual engineering applications. The finishing technology of complex internal flow channels in additive manufacturing has become an internationally recognized industry difficult technology.

[0004] Patent CN114734365B proposes a water-based two-phase flow polishing medium finishing method for the surface of fine and complex inner flow channels, which is driven by hydraulic thrust to flow a water-based polishing medium with a viscosity of less than 1000cP at a flow rate of >5m / s in the fine inner flow channel, and the abrasive particles move at high speed with the water-based fluid to produce high-speed and high-frequency micro-cutting, and finally achieve efficient polishing of fine and complex inner flow channels with a diameter of ≤3mm and an aspect ratio of ≥50:1. However, when the water-based two-phase flow polishing medium is polished at high speed, the abrasive particles are easily unevenly distributed along the radial direction of the inner flow channel bend due to the inertial centrifugal force when the polishing medium flows through the inner flow channel bend, that is, the number of abrasive particles near the outer wall of the inner flow channel bend is significantly more than that of the inner wall. The higher the flow rate of the polishing medium and the smaller the turning angle / bending radius of the inner flow channel, the more serious this phenomenon is, resulting in uneven polishing of the inner and outer sides of the inner flow channel bend, and even over-polishing, size deviation or even damage of the outer wall due to 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. The method of reducing the driving pressure and flow rate of the polishing medium can improve the problems of non-uniform polishing at the bends of the flow channel, and even dimensional deviations and damage. However, further engineering tests have shown that reducing the driving pressure and flow rate of the polishing medium will significantly reduce the high-speed micro-cutting effect and polishing efficiency of the high-speed water-based two-phase flow, and even some high-hardness alloys such as CoCoMo high-temperature alloys cannot be polished due to insufficient movement speed and cutting force of the abrasive particles. Summary of the invention

[0006] The purpose of the present invention is to provide a chemical-physical coupling polishing medium, method and device for fine and complex internal flow channels, which can improve the problems of uneven polishing at the bends of the flow channels, and even dimensional deviations and damage caused by excessive driving pressure and flow rate when fine and complex internal flow channels are polished and additively manufactured using high-speed water-based two-phase flow polishing medium technology in the prior art.

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

[0008] A chemical-physical coupling polishing medium with a fine and complex internal flow channel, the chemical-physical coupling 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 coupling polishing medium is an arbitrary ratio.

[0009] Furthermore, the dynamic chemical removal rate of the chemical polishing liquid flowing in the micro-inner flow 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-inner flow 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 for the material of the part to be polished.

[0011] In order to achieve the above technical effects, the present invention also provides a chemical-physical coupling polishing method for a fine and complex internal flow channel, 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 into the water-based two-phase flow polishing medium to form composite polishing liquids in different dosage ratios;

[0015] Under the preset polishing parameter conditions, the composite polishing liquid with different dosage ratios is respectively input into the micro-inner flow channel of the corresponding part sample to be polished for the preset polishing test, and the initial flow value φ of the composite polishing liquid in the inner flow channel under the preset polishing parameter conditions is obtained by the flow meter. 0 , preset instantaneous flow value of composite polishing liquid when polishing test is completed φ 1 The preset polishing parameter conditions include the polishing experiment time t, the constant flow rate v of the composite polishing liquid 0 , 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 value of composite polishing liquid when 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;

[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 standard driving pressure and temperature corresponding to the composite polishing liquid of 25% to 50% are used to perform chemical-physical coupling polishing on the fine and complex internal flow channel under the standard driving pressure and temperature conditions.

[0018] Furthermore, the water-based two-phase flow polishing medium includes, by mass concentration, 8 to 80 g / L of solid abrasive, 3 to 8 g / L of viscosity enhancer, 6 to 12 g / L of defoamer, 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 H 2 O, 10-20 g FeCl 3 , 1-3 g EDTA and 2-5 g Na 2 MoO 4 The HCl content in the hydrochloric acid solution is 30% to 37%, and the HNO content in the nitric acid solution is 3 The content 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 value of the composite polishing liquid, is the instantaneous flow value of the composite polishing liquid when the polishing test is completed, t is the polishing test time under the preset polishing parameter conditions, and v 0 It is a constant flow rate of composite polishing liquid.

[0020] Furthermore, 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.

[0021] In order to achieve the above-mentioned technical effects, the present invention also provides a chemical-physical coupling polishing device for fine and complex internal flow channels, which is used to implement the chemical-physical coupling polishing method for fine internal flow channels, including a cylinder body that contains the composite polishing liquid, the inner wall of the cylinder body is inlaid with an inner liner made of 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 arranged in the cylinder body, and the piston is made of aluminum alloy that has been subjected to micro-arc oxidation surface ceramic treatment; 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 about 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 embedding the polymer material liner into the material cylinder adopts a hot pressing embedding 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 pressure 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 prior art, the beneficial effects of the present invention are as follows: 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 performs synchronous coordination of physical polishing of abrasive particles in the two-phase flow, thereby innovating a chemical-physical coupling polishing method of chemical components and physical components. On the one hand, the removal and polishing efficiency of the water-based two-phase flow polishing medium can be significantly enhanced; on the other hand, the driving pressure and flow rate required for the composite polishing liquid can be reduced 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. c1 The quantitative relationship between the chemical-physical coupling removal rate v is calculated, and the quantitative relationship is ensured by regulating the driving pressure and the temperature of the composite polishing liquid. Finally, 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, and realize the target requirements of roughness Ra<1.6μm and turning deformation controlled within 0.1mm.

[0027] To improve the existing technology that only uses high-speed water-based two-phase flow polishing medium technology to finish additive manufacturing of fine and complex internal flow channels, due to excessive driving pressure and flow rate, it is easy to produce non-uniform polishing at the channel bends, and even dimensional deviations and damage. The existing technology only uses high-speed water-based two-phase flow to achieve a roughness Ra<1.6μm, and the turning deformation is controlled within 0.25mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The flow chart of the chemical-physical coupling 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 a composite polishing liquid in Example 2. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the embodiments and drawings. However, it should not be understood that the scope of the above subject matter of the present invention is limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0031] Example 1

[0032] See also Figure 1 , a chemical-physical coupling 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 into the water-based two-phase flow polishing medium to form composite polishing liquids in different dosage ratios;

[0036] Under the preset polishing parameter conditions, the composite polishing liquid with different dosage ratios is respectively input into the micro-inner flow channel of the corresponding part sample to be polished for the preset polishing test, and the initial flow value φ of the composite polishing liquid in the inner flow channel under the preset polishing parameter conditions is obtained by the flow meter. 0 , preset instantaneous flow value of composite polishing liquid when polishing test is completed φ 1 The preset polishing parameter conditions include the polishing experiment time t, the constant flow rate v of the composite polishing liquid 0 , preset driving pressure of the composite polishing liquid;

[0037] According to the initial flow value φ of the composite polishing liquid under the preset polishing parameter conditions 0 , preset instantaneous flow value of composite polishing liquid when polishing test is completed φ 1 , 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 content of 25% to 50% is used to perform chemical-physical coupling 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, and the chemical polishing components in the water-based two-phase flow polishing medium dissolve and soften the metal surface, and the physical polishing of the abrasive particles in the two-phase flow is synchronously coordinated, thereby innovating a chemical-physical coupling polishing method of chemical components and physical components. On the one hand, the removal and polishing efficiency of the water-based two-phase flow polishing medium can be significantly enhanced; on the other hand, the driving pressure and flow rate required for the composite polishing liquid can be reduced while achieving the same polishing effect as the water-based two-phase flow polishing medium without adding chemical polishing liquid, thereby improving the prior art that when the high-speed water-based two-phase flow polishing medium technology is used alone to finish the additive manufacturing of fine and complex internal flow channels, the high driving pressure and flow rate are too high, which easily causes non-uniform polishing at the bends of the flow channels, and even dimensional deviations and damage. The problem is avoided that the high-speed micro-cutting effect and polishing efficiency of the high-speed water-based two-phase flow are significantly reduced due to the reduction of the driving pressure and flow rate of the high-speed water-based two-phase flow polishing medium, and even some high-hardness alloys such as CoCoMo high-temperature alloys cannot be polished due to insufficient movement speed and cutting force of the abrasive particles.

[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 tolerance and damage problems. The dynamic flow chemical removal rate of the composite polishing liquid in the fine internal flow channel v c2 The polishing effect is best when the physical removal rate of the abrasive in the composite polishing liquid is equal to or equivalent.

[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 solution in the fine inner flow channel according to engineering experience. c1 Determination of dynamic flow chemistry removal rate v c2 The chemical-physical coupling removal rate was obtained by the preset polishing parameter test method. Based on the dynamic flow chemical removal rate v c2 Based on the specific relationship with 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 best 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 with a fine and complex internal flow channel, wherein the chemically and physically coupled polishing medium includes 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 specific engineering practice, the selection of the components of the chemical polishing liquid added to the water-based two-phase flow polishing medium is very critical. It must have a good dissolving and softening effect on the surface of the metal material, and avoid excessive corrosion of the material surface and damage and failure of the original thickener, dispersant, suspending agent, and defoaming agent in the water-based two-phase flow polishing medium. In this embodiment, the water-based two-phase flow polishing medium includes 8-80g / L of solid abrasive, 3-8g / L of thickener, 6-12g / L of defoaming agent, 0.5-5g / L of lubricant, 10-20g / L of dispersant, and 0.5-1g / L of antifreeze. The chemical polishing liquid includes: 1-5ml of hydrochloric acid solution, 1-3ml of nitric acid solution, 10-25ml of H 2 O, 10-20 g FeCl 3 , 1-3 g EDTA and 2-5 g Na 2 MoO 4 The content of HCl in the hydrochloric acid solution is 30% to 37%, and the content of HNO in the nitric acid solution is 3 The content is 40% to 70%. Adding a unique complexing agent EDTA can form a stable complex with metal ions, quickly complexing metal ions from the surface of the material to achieve dissolution and softening of the metal surface, and can reduce the content of hydrochloric acid and nitric acid in the chemical polishing liquid. The reduction in the content of hydrochloric acid and nitric acid will significantly alleviate the effect of strong acid on the deterioration and failure of thickeners, defoamers, dispersants, and antifreeze agents in the water-based two-phase flow polishing medium. Secondly, due to the addition of chemical polishing liquid, the softening and dissolution of the metal surface of the inner flow channel is accelerated, so the low-pressure and low-speed composite polishing medium can achieve the same excellent polishing effect compared to the single water-based two-phase flow polishing. In addition, in this embodiment, the addition of chemical polishing liquid in the water-based two-phase flow polishing medium accelerates the polishing process, the chemical softening and dissolving process can avoid rust on the surface of the inner flow channel, and the rust inhibitor will reduce the catalyst effect in the chemical polishing medium. Therefore, compared with the traditional high-speed water-based two-phase flow polishing medium, the new composite polishing liquid removes 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 test time t (10 to 30 min) and the constant flow rate v of the composite polishing liquid in the preset polishing parameters, 0 (3m / s), through the formula The chemical-physical coupling removal rate v of the composite polishing liquid under the preset driving pressure is calculated. The chemical-physical coupling removal rate v is approximately the static chemical polishing removal rate v of the part material. c1 The 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 equivalent. If the dynamic chemical removal rate is too fast, it will cause excessive corrosion on the material surface, produce defects such as deep pits and holes, or generate a dense and strong oxide film. Physical polishing is difficult to remove the deep damage layer or dense and strong oxide film produced by chemical polishing. After chemical-physical coupling polishing, the surface roughness of the inner flow channel increases. On the contrary, if the physical removal rate is too fast, chemical polishing will not have time to fully dissolve and soften the metal surface. Physical polishing will not be able to efficiently remove hard micro-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 in 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 in 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 with the water-based two-phase flow polishing medium alone.

[0047] Based on the same inventive concept, the present embodiment also provides a chemical-physical coupling polishing device for fine and complex internal flow channels, which is used to implement the chemical-physical coupling polishing method for fine internal flow channels, including a cylinder body that contains the composite polishing liquid, the inner wall of the cylinder body is inlaid with an inner liner made of 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 arranged in the cylinder body, and the piston is made of aluminum alloy that has been subjected to micro-arc oxidation surface ceramic treatment; 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, the inner liner made of polymer material is inserted into the cylinder body of the material cylinder, and is closely attached to the inner wall of the material cylinder to prevent the chemical polishing liquid in the polishing medium from dissolving and corroding the wall of the material cylinder. Polymer materials can be selected from polytetrafluoroethylene, ultra-high molecular weight polyethylene, polyvinylidene fluoride, perfluoroalkoxy resin, polyphenylene sulfide, etc. The method of inserting the polymer material inner liner into the material cylinder adopts the hot pressing embedding method. The polymer material inner liner is first heated to above its glass transition temperature (Tg). At this time, the polymer material will change from a glass state to a high elastic state or a viscous flow state, becoming soft and having good fluidity. Then put it into the cylinder body, design a special mold to apply a pressure of 2 to 6MPa, so that the inner liner is fully attached to the inner wall of the material cylinder under pressure and cooling. Specifically, the shape of the mold matches the internal shape of the material cylinder. The mold has an outer fixed part and an inner movable part. When the mold is put on the inner liner and put into the material cylinder, the inner movable part is driven to move toward the outer layer by a screw and a gear. During the movement, the pressure generated by the outer layer makes the inner liner close to the inner wall of the material 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 coupling polishing device of the present invention can solve the problem of corrosion damage to some components in the equipment of the original water-based two-phase flow polishing medium without adding chemical polishing components after the chemical polishing liquid is added to the water-based two-phase flow polishing medium. It avoids the problem that the chemical polishing liquid will dissolve the cylinder wall surface, resulting in a decrease in the tightness of the gap between the sealing piston and the cylinder wall surface, and even 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 aluminum oxide 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 aluminum oxide ceramic layer of about 80-100 μm, and a bonding strength between the aluminum oxide 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 grown in situ on the surface of the aluminum alloy with metallurgical bonding 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 improve 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, so that the sealing ring around the piston can be tightly attached to the inner wall of the polymer liner after extrusion deformation, so as to further ensure good sealing performance.

[0053] Example 2

[0054] See also Figure 1 and Figure 2 This embodiment takes the finishing test of a two-dimensional CoCrMo high-temperature alloy inner flow channel sample with a turning structure as an example to explain in detail the chemical-physical coupling polishing method of the fine and complex inner flow channel of the present invention. The inner flow channel to be finished is obtained by laser additive manufacturing technology, and the structural parameters are: the diameter D of the fine inner flow channel is about 2.5mm, the total length of the flow channel is about 100mm, the aspect ratio is greater than 50:1, the flow channel includes a turning structure and an O-shaped bend, the material is a high-temperature alloy, and the original roughness Ra of the inner flow channel is about 5.8μm. The specific processing method is as follows:

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

[0056] In this embodiment, the water-based two-phase flow polishing medium includes 40.2 g / L of solid abrasive, 5.1 g / L of viscosity enhancer, 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 agent, measured by mass concentration.

[0057] The chemical polishing solution includes: 3.3 ml of hydrochloric acid solution, 2.6 ml of nitric acid solution, 20.9 ml of H 2 O, 12.7 g of FeCl 3 , 2.6 g of EDTA and 2.9 g of Na 2 MoO 4 The content of HCl in the hydrochloric acid solution is 30% to 37%, and the content of HNO in the nitric acid solution is 3 The content is 40% to 70%.

[0058] Step 2: Immerse the part sample 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 liquid, and a spiral micrometer is used to measure the plane thickness of the part. The static chemical polishing removal rate v of the part material is obtained based on the measured value of the change in the plane thickness of the part 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 0.01 μm / s. The reason is that the static chemical removal rate v c1 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 three, adding the chemical polishing liquid in different dosage ratios to the water-based two-phase flow polishing medium, slowly adding the chemical polishing liquid to the water-based two-phase flow polishing medium and stirring at high speed to form a composite polishing liquid with different dosage ratios; the reason is that 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 parameter conditions, respectively input the composite polishing liquid with different dosage ratios into the micro-inner 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 parameter conditions. Preset instantaneous flow value of composite polishing liquid when 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;

[0065] In this embodiment, during the chemical polishing liquid immersion and the composite polishing liquid polishing process, the temperature was regulated to be 45° C. and the driving pressure was 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 The instantaneous flow value of the composite polishing liquid when the polishing test is completed According to the polishing test time t (10-30 min) and the constant flow rate v of the composite polishing liquid in the preset polishing parameters 0 (3m / s), through 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. c1 The 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 internal flow channels of the parts to be polished are polished.

[0068] like Figure 2 As shown, the sample of the inner flow channel of the two-dimensional additively manufactured CoCrMo high-temperature alloy with a turning structure after polishing with the chemical-physical coupled composite polishing liquid in this embodiment is cut, and the inner surface of the flow channel can be clearly seen to be flattened close to the machined surface and has a significant finishing effect, and the surface is smooth and bright. The additive manufacturing powder without residue, inlay and semi-sintering is detected by metallographic examination, and the surface roughness of the inner flow channel Ra<1.6μm and the turning deformation is controlled within 0.08mm.

[0069] Although the water-based two-phase flow technology can improve the problems of non-uniform polishing, even dimensional deviation and damage at the bends of the flow channel by reducing the driving pressure and flow rate of the polishing medium when finishing the fine and complex internal flow channels of additive manufacturing, further engineering experiments have shown that the method of reducing the driving pressure and flow rate of the polishing medium will significantly reduce the high-speed micro-cutting effect and polishing efficiency of the high-speed water-based two-phase flow, and even some high-hardness alloys such as CoCoMo high-temperature alloys cannot be polished due to insufficient movement speed and cutting force of the abrasive particles. The basic improvement idea proposed by the present invention is to add a certain proportion of chemical polishing liquid to the water-based two-phase flow polishing medium, and dissolve and soften the metal surface through the chemical polishing components in the two-phase flow polishing medium, which can significantly enhance the physical removal rate and polishing effect of the abrasive particles on the synchronously softened metal surface, that is, the chemical components and physical components in the polishing medium will significantly enhance the removal and polishing efficiency of the water-based two-phase flow through the mechanism of chemical-physical coupling. In other words, compared with the water-based two-phase flow polishing medium without adding chemical components, the driving pressure and flow rate required for the water-based two-phase flow polishing medium containing chemical components can be lower under the same polishing effect. The invention improves the high-speed water-based two-phase flow technology described in patent CN114734365B, which is used for finishing additive manufacturing of fine and complex internal flow channels, and easily causes non-uniform polishing at the channel bends, and even dimensional deviations and damage due to excessively high driving pressure and flow rate. At the same time, the invention overcomes the problem that the high-speed micro-cutting effect and polishing efficiency of the high-speed water-based two-phase flow will be significantly reduced after reducing the driving pressure and flow rate of the original water-based two-phase flow polishing medium.

[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 protection scope of the present invention.

Claims

1. A chemical-physical coupling polishing medium with fine and complex internal flow channels, characterized in that: The chemical-physical coupling polishing medium comprises a water-based two-phase flow polishing medium and a chemical polishing liquid. The usage ratio of the water-based two-phase flow polishing medium and the chemical polishing liquid in the chemical-physical coupling polishing medium is any ratio.

2. The chemical-physical coupling polishing medium for fine and complex internal flow channels according to claim 1, characterized in that: The dynamic chemical removal rate of the chemical polishing liquid flowing in the micro-inner flow 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-inner flow channel immersed in the chemical polishing liquid. c1 12.5% ​​to 25%.

3. The chemical-physical coupling polishing medium for fine and complex internal flow channels according to claim 2, characterized in that: The static chemical removal rate of the chemical polishing liquid on the material of the part to be polished is not less than 0.01 μm / s.

4. A chemical-physical coupling 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 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 ; Adding the chemical polishing liquid in different dosage ratios into the water-based two-phase flow polishing medium to form composite polishing liquids in different dosage ratios; Under the preset polishing parameter conditions, different amounts of composite polishing liquid are respectively input into the micro-inner flow channel of the corresponding part sample to be polished for the preset polishing test, and the initial flow value of the composite polishing liquid in the inner flow channel under the preset polishing parameter conditions is obtained by the flow meter. Preset instantaneous flow value of composite polishing liquid when polishing test is completed 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; According to the initial flow value of the composite polishing liquid under the preset polishing parameter conditions Preset instantaneous flow value of composite polishing liquid when 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; 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 standard driving pressure and temperature corresponding to the composite polishing liquid of 25% to 50% are used to perform chemical-physical coupling polishing on the fine and complex internal flow channel under the standard driving pressure and temperature conditions.

5. The chemical-physical coupling polishing method for fine and complex internal flow channels according to claim 4, characterized in that: Measured by mass concentration, the water-based two-phase flow polishing medium includes 8-80 g / L of solid abrasive, 3-8 g / L of viscosity enhancer, 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 liquid 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 HCl content in the hydrochloric acid solution is 30%-37%, and the HNO3 content in the nitric acid solution is 40%-70%.

6. The chemical-physical coupling polishing method for fine and complex internal flow channels according to claim 5, characterized in that: Chemical-physical coupling removal rate of composite polishing slurry under preset driving pressure Among them is The initial flow value of the composite polishing liquid, is the instantaneous flow value of the composite polishing liquid when the polishing test is completed, t is the polishing experiment time under the preset polishing parameter conditions, and v0 is the constant flow rate of the composite polishing liquid.

7. The chemical-physical coupling polishing method for a fine and complex inner flow channel according to claim 4, characterized in that: The preset driving pressure is 50% or more lower than the conventional driving pressure, which is the driving pressure that enables the flow channel in the part to be polished to reach the designed roughness when the water-based two-phase flow polishing medium is used alone for polishing.

8. A chemical-physical coupling polishing device for fine and complex internal flow channels, used for implementing the chemical-physical coupling polishing method for fine internal flow channels as claimed in any one of claims 4 to 7, characterized in that: It comprises a cylinder body for containing the composite polishing liquid, the inner wall of the cylinder body is inlaid with an inner liner made of polymer material, the polymer material comprises one or more combinations of polytetrafluoroethylene, polyethylene, polypropylene, nylon, polyetheretherketone; a piston for driving the composite polishing liquid is arranged in the cylinder body, the piston is made of aluminum alloy treated by micro-arc oxidation surface ceramicization; the discharge end of the cylinder body is connected with the fine inner flow channel of the part to be polished through a material guide pipe.

9. The chemical-physical coupling polishing device for fine and complex internal flow channels according to claim 8, characterized in that: During the micro-arc oxidation surface ceramicization process of the piston, the electrical parameters for the growth of the micro-arc aluminum oxide 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 aluminum oxide ceramic layer of about 80-100 μm, and a bonding force between the aluminum oxide ceramic layer and the aluminum alloy substrate greater than 120 MPa.

10. The chemical-physical coupling polishing device for fine and complex internal flow channels according to claim 8, characterized in that: A sealing ring is arranged 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.

11. The chemical-physical coupling polishing device for fine and complex internal flow channels according to claim 8, characterized in that: The method of inserting the polymer material liner into the material cylinder adopts the hot pressing embedding method. The polymer material liner is first heated to above its glass transition temperature, and then the heated polymer material liner is placed in the cylinder body. A pressure of 2 to 6 MPa is applied by a pressurized mold to make the polymer material liner fit with the inner wall of the material cylinder under pressure and cooling.

Images