Finishing method and chemical polishing device for additive manufacturing micro complex inner flow channel

Abstract

The invention provides a finishing method and a chemical polishing solution device for additive manufacturing of a fine and complex inner flow channel. The finishing method for additive manufacturing of the fine and complex inner flow channel comprises the following steps that firstly, a chemical polishing solution is prepared; 2, preheating the chemical polishing solution; thirdly, polishing operation is started, and chemical polishing is stopped when the flow increasing value of the chemical polishing liquid reaches a first set increasing value; 4, cleaning and drying operation is carried out; 5, the viscosity and the abrasive particle size of a high-speed abrasive particle flow polishing medium are selected; sixthly, high-speed abrasive flow polishing operation is started, and when the discharging mass flow of the high-speed abrasive flow polishing medium is increased to reach a second set increasing value, high-speed abrasive flow polishing is stopped; and 7, cleaning and drying. According to the invention, the surface roughness of the fine inner flow channel can reach Ralt after being polished; the roughness difference of the upper surface and the lower surface with large inner flow channel roughness difference and the roughness difference of the inner side and the outer side of a turn are lt; and the percentage is less than 15%.

Description

Technical Field

[0001] The present invention relates to the technical field of precision machining of parts, and in particular to a finishing method and a chemical polishing device for additively manufacturing fine and complex internal flow channels. Background Art

[0002] Parts with fine internal flow channel structures have extremely wide applications in the industrial field, especially parts related to fluid power systems often have complex internal cavity structures such as fine flow channels, deep holes, and micro-flow channels connected with deep holes, which play the role of transporting, exchanging or applying hydraulic pressure to fluids, such as various 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). 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 forming. It makes it possible to form complex, fine and complex internal flow channel parts in an integrated manner, and therefore its application in the industrial field is increasing. However, in the process of forming parts, additive manufacturing technology has its own process characteristics such as temperature gradient and layer-by-layer forming, which leads to the presence of semi-sintered or bonded powder particles and surface "step" effect on the surface of the inner flow channel of the part. This rough inner flow channel will cause turbulence, eddy currents and a sharp increase in fluid resistance along the flow path during the fluid movement process, and even cause the fluid to lose control, produce vibrations and reduce the service life of the parts. The rough surface 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 inner flow channels of most additively manufactured parts need to be polished before they can be used in actual engineering. The finishing technology of complex inner flow channels in additive manufacturing has become an internationally recognized industry difficult technology.

[0003] The existing technology is to drive the water-based polishing medium with a viscosity of less than 1000cP to flow at a flow rate of >5m / s in the fine inner flow channel through the hydraulic thrust, 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 initial roughness difference between the upper surface (overhanging surface) and the lower surface (non-overhanging surface) of the complex inner flow channel formed by the additive manufacturing (3D printing) process is large, the flow rate is relatively small in the surface area with larger roughness due to the greater friction resistance when using water-based two-phase flow polishing, and on the contrary, the flow rate is relatively high in the surface area with smaller roughness. This flow rate difference directly causes the problem of uneven polishing. The surface on the side with smaller initial roughness is easier to be polished, while the surface on the other side with larger initial roughness will only be slightly polished. After polishing, the difference in roughness between the upper and lower surfaces is even greater than the initial state. In addition, due to the inertial centrifugal force, the water-based two-phase flow technology is prone to uneven radial distribution of abrasive particles along the inner channel bend during high-speed polishing, that is, the number of abrasive particles near the outer wall of the inner channel bend is significantly greater than that of the inner wall. The higher the flow rate of the polishing medium and the smaller the turning angle / bending radius, the more serious this phenomenon is, resulting in uneven polishing of the inner and outer sides of the bend, and even dimensional deviation or damage of the outer wall due to over-polishing. Therefore, when using water-based two-phase flow technology to finish additive manufacturing of fine and complex inner channels, it is easy to produce uneven polishing at the channel bends and the upper and lower surfaces with large initial roughness differences, and even dimensional deviation and damage problems, and new solutions or improvement measures need to be proposed. Summary of the invention

[0004] In view of this, the embodiments of this specification provide a finishing method and a chemical polishing device for additively manufacturing fine and complex internal flow channels to achieve the purpose of improving the polishing effect.

[0005] The embodiments of this specification provide the following technical solutions: a finishing method for additive manufacturing of fine and complex internal flow channels, comprising the following steps:

[0006] Step 1: Prepare chemical polishing solution;

[0007] Step 2: Pour the prepared chemical polishing liquid into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to a set temperature;

[0008] Step 3, adjusting the pump pressure of the chemical polishing liquid container, reading the flow value of the chemical polishing liquid flowing out of the inner flow channel of the workpiece at the beginning, and calculating the starting flow rate of the chemical polishing liquid; starting the polishing operation when adjusting the flow rate of the chemical polishing liquid to the set flow rate, and stopping the chemical polishing operation when the flow rate of the chemical polishing liquid increases to the first set increase value;

[0009] Step 4: Use ultrasonic immersion to clean the inner flow channel of the workpiece. After the cleaning is completed, rinse it with pure water several times and then dry it;

[0010] Step 5: Select the viscosity and abrasive particle size of the high-speed abrasive flow polishing medium;

[0011] Step 6: Adjust the high-speed abrasive flow hydraulic thrust. When the mass flow is greater than the set threshold value through the hydraulic thrust adjustment, the high-speed abrasive flow polishing operation is started; when it is monitored that the discharge mass flow of the high-speed abrasive flow polishing medium at the outlet of the inner flow channel of the workpiece reaches a second set increase value, the high-speed abrasive flow polishing operation is stopped;

[0012] Step 7: Use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium in the inner flow channel of the workpiece, and then use ultrasonic immersion to clean the inner flow channel of the workpiece. After cleaning, rinse with pure water several times and then dry.

[0013] Furthermore, step one specifically comprises: preparing a chemical polishing solution by using deionized water, hydrochloric acid, nitric acid, ferric chloride, cerium oxide and sodium molybdate.

[0014] Furthermore, step three is specifically as follows:

[0015] The set flow rate of the chemical polishing liquid is 0.5-2 m / s;

[0016] The first set boost value is 15% to 50%.

[0017] Furthermore, step three also includes controlling the depth of the chemical etching layer to be between 100 μm and 200 μm during the chemical polishing operation.

[0018] Furthermore, in step 4, a soaking liquid for soaking and cleaning the workpiece is prepared using synthetic fatty acid monoethanolamide polyalkoxy ether, alkyl polyoxyethylene ether phosphate salt, sodium metasilicate, sodium tripolyphosphate and sodium carbonate.

[0019] Furthermore, in step five, the viscosity of the high-speed abrasive flow polishing medium ranges from 1000 cP to 8000 cP, and the abrasive particle size ranges from 60 to 1200 meshes.

[0020] Furthermore, step five also includes: adjusting the viscosity of the high-speed abrasive flow polishing medium by adding ethylene-propylene branched copolymer into the high-speed abrasive flow polishing medium.

[0021] Furthermore, the threshold value in step six is ​​set to 30 MPa.

[0022] Furthermore, the second set improvement value in step six is ​​15% to 60%.

[0023] The present invention also provides a finishing method for additively manufacturing a fine and complex internal flow channel, comprising the following steps:

[0024] Step 1: Perform high-speed water-based two-phase flow polishing on the inner flow channel of the workpiece, and stop the high-speed water-based two-phase flow polishing when the flow rate of the high-speed water-based two-phase flow medium reaches a third set increase value;

[0025] Step 2: preparing chemical polishing solution;

[0026] Step 3: Pour the prepared chemical polishing liquid into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to the set temperature;

[0027] Step 4, adjusting the pump pressure of the chemical polishing liquid container, reading the flow value of the chemical polishing liquid flowing out of the inner flow channel of the workpiece at the beginning, and calculating the starting flow rate of the chemical polishing liquid; starting the polishing operation when adjusting the flow rate of the chemical polishing liquid to the set flow rate, and stopping the chemical polishing operation when the flow rate of the chemical polishing liquid increases to the first set increase value;

[0028] Step 5: Use ultrasonic immersion to clean the inner flow channel of the workpiece. After the cleaning is completed, rinse it with pure water several times and then dry it;

[0029] Step 6: Select the viscosity and abrasive particle size of the high-speed abrasive flow polishing medium;

[0030] Step 7, adjusting the high-speed abrasive flow hydraulic thrust, when the mass flow is greater than the set threshold value through the hydraulic thrust adjustment, the high-speed abrasive flow polishing operation is started; when it is monitored that the discharge mass flow of the high-speed abrasive flow polishing medium at the outlet of the inner flow channel of the workpiece reaches a second set increase value, the high-speed abrasive flow polishing operation is stopped;

[0031] Step 8: Use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium in the inner flow channel of the workpiece, and then use ultrasonic immersion to clean the inner flow channel of the workpiece. After cleaning, rinse with pure water several times and then dry.

[0032] Furthermore, a high-speed water-based two-phase flow medium is prepared by using deionized water, aluminum oxide and rosin resin emulsion.

[0033] Furthermore, step two specifically comprises: preparing a chemical polishing solution by using deionized water, hydrochloric acid, nitric acid, ferric chloride, cerium oxide and sodium molybdate.

[0034] Furthermore, step four is specifically as follows:

[0035] The set flow rate of the chemical polishing liquid is 0.5-2 m / s;

[0036] The first set boost value is 15% to 50%.

[0037] Furthermore, step four also includes controlling the depth of the chemical etching layer to be between 100 μm and 200 μm during the chemical polishing operation.

[0038] Furthermore, in step five, a soaking liquid for soaking and cleaning the workpiece is prepared using synthetic fatty acid monoethanolamide polyalkoxy ether, alkyl polyoxyethylene ether phosphate salt, sodium metasilicate, sodium tripolyphosphate and sodium carbonate.

[0039] Furthermore, in step six, the viscosity of the high-speed abrasive flow polishing medium ranges from 1000 cP to 8000 cP, and the abrasive particle size ranges from 60 to 1200 meshes.

[0040] Furthermore, step six also includes: adjusting the viscosity of the high-speed abrasive flow polishing medium by adding ethylene-propylene branched copolymer into the high-speed abrasive flow polishing medium.

[0041] Furthermore, the threshold value in step seven is set to 30 MPa.

[0042] Furthermore, the second set boost value in step seven is 15% to 60%.

[0043] The present invention also provides a chemical polishing liquid device, which is used for the chemical polishing operation in the above-mentioned additive manufacturing fine and complex internal flow channel finishing method, and the chemical polishing liquid device includes:

[0044] A chemical polishing liquid container, used for placing chemical polishing liquid;

[0045] The chemical polishing liquid recovery device is arranged at a distance from the chemical polishing liquid container, and the chemical polishing liquid recovery device is connected to the chemical polishing liquid container through a diversion pipeline and a reflux pipeline, and the workpiece is arranged in the diversion pipeline.

[0046] Furthermore, the diversion pipeline includes:

[0047] A diversion pump is arranged in the chemical polishing liquid container;

[0048] The inlet of the valve is connected to the outlet of the diversion pump, and the outlet of the valve is connected to the inlet of the workpiece;

[0049] The flow meter has an inlet connected to an outlet of the workpiece, and the outlet of the flow meter is connected to a chemical polishing liquid recovery device through a first flow guide pipe.

[0050] Furthermore, the reflux pipeline includes a reflux pump and a second guide pipe. The reflux pump is arranged in the chemical polishing liquid recovery device. One end of the second guide pipe is connected to the outlet of the reflux pump, and the other end of the second guide pipe is connected to the chemical polishing liquid container.

[0051] Furthermore, a constant temperature heating device is also provided in the chemical polishing liquid container.

[0052] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above-mentioned technical solutions adopted in the embodiments of this specification include at least the following: the technology of the present invention is aimed at additively manufactured fine and complex internal flow channels with a diameter of 1.5mm to 3mm and an aspect ratio ≥50:1. A finishing method for additively manufactured fine and complex internal flow channels is used to achieve a surface roughness of the fine internal flow channels that reaches Ra<1.6μm after polishing, and the difference in roughness between the upper and lower surfaces of the internal flow channels and the inner and outer sides of the turns with large differences in roughness is less than 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 is a schematic diagram of a flow chart of an embodiment of the present invention;

[0055] Figure 2 is a schematic structural diagram of a chemical polishing device in an embodiment of the present invention;

[0056] Figure 3 This is a polishing effect diagram of Example 1;

[0057] Figure 4 This is a polishing effect diagram of the upper surface of Example 2;

[0058] Figure 5 This is a diagram showing the polishing effect of the lower surface of Example 2.

[0059] The reference numerals in the figure are: 1. chemical polishing liquid container; 2. constant temperature heating device; 3. diversion pump; 4. valve; 5. workpiece; 6. flow meter; 7. first diversion pipe; 8. sealing assembly; 9. tooling; 10. chemical polishing liquid recovery device; 11. chemical polishing liquid; 12. reflux pump; 13. second diversion pipe. DETAILED DESCRIPTION

[0060] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0061] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0062] like Figure 1 As shown, an embodiment of the present invention provides a finishing method for additively manufactured fine and complex internal flow channels, which is used to polish additively manufactured fine and complex internal flow channels with a diameter of 1.5 mm to 3 mm and an aspect ratio of ≥50:1, and specifically includes the following steps:

[0063] Step 1: Prepare chemical polishing solution;

[0064] Step 2: Pour the prepared chemical polishing liquid into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to a set temperature;

[0065] Step 3, adjusting the pump pressure of the chemical polishing liquid container, reading the flow value of the chemical polishing liquid flowing out of the inner flow channel of the workpiece at the beginning, and calculating the starting flow rate of the chemical polishing liquid; starting the polishing operation when adjusting the flow rate of the chemical polishing liquid to the set flow rate, and stopping the chemical polishing operation when the flow rate of the chemical polishing liquid increases to the first set increase value;

[0066] Step 4: Use ultrasonic immersion to clean the inner flow channel of the workpiece. After the cleaning is completed, rinse it with pure water several times and then dry it;

[0067] Step 5: Select the viscosity and abrasive particle size of the high-speed abrasive flow polishing medium;

[0068] Step 6: Adjust the high-speed abrasive flow hydraulic thrust. When the mass flow is greater than the set threshold value through the hydraulic thrust adjustment, the high-speed abrasive flow polishing operation is started; when it is monitored that the discharge mass flow of the high-speed abrasive flow polishing medium at the outlet of the inner flow channel of the workpiece reaches a second set increase value, the high-speed abrasive flow polishing operation is stopped;

[0069] Step 7: Use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium in the inner flow channel of the workpiece, and then use ultrasonic immersion to clean the inner flow channel of the workpiece. After cleaning, rinse with pure water several times and then dry.

[0070] First, the chemical polishing process is used to remove the residual powder and particles in the additively manufactured fine inner flow channel, further improve the permeability of the inner flow channel to the high-speed abrasive flow polishing medium and reduce the initial roughness difference between the upper and lower surfaces of the additively manufactured inner flow channel. On this basis, high-speed abrasive flow polishing is then used to achieve uniform polishing of the upper and lower surfaces of the inner flow channel and its corners and achieve higher surface polishing quality.

[0071] The polishing method of the embodiment of the present invention can achieve a surface roughness of Ra<3.2μm for the fine inner flow channel after polishing, and the difference in roughness between the upper and lower surfaces of the inner flow channel and the inner and outer sides of the turn is less than 15%.

[0072] In another embodiment, the method specifically includes the following steps:

[0073] Step 1: Perform high-speed water-based two-phase flow polishing on the inner flow channel of the workpiece, and stop the high-speed water-based two-phase flow polishing when the flow rate of the high-speed water-based two-phase flow medium reaches a third set increase value;

[0074] Step 2: preparing chemical polishing solution;

[0075] Step 3: Pour the prepared chemical polishing liquid into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to the set temperature;

[0076] Step 4, adjusting the pump pressure of the chemical polishing liquid container, reading the flow value of the chemical polishing liquid flowing out of the inner flow channel of the workpiece at the beginning, and calculating the starting flow rate of the chemical polishing liquid; starting the polishing operation when adjusting the flow rate of the chemical polishing liquid to the set flow rate, and stopping the chemical polishing operation when the flow rate of the chemical polishing liquid increases to the first set increase value;

[0077] Step 5: Use ultrasonic immersion to clean the inner flow channel of the workpiece. After the cleaning is completed, rinse it with pure water several times and then dry it;

[0078] Step 6: Select the viscosity and abrasive particle size of the high-speed abrasive flow polishing medium;

[0079] Step 7, adjusting the high-speed abrasive flow hydraulic thrust, when the mass flow is greater than the set threshold value through the hydraulic thrust adjustment, the high-speed abrasive flow polishing operation is started; when it is monitored that the discharge mass flow of the high-speed abrasive flow polishing medium at the outlet of the inner flow channel of the workpiece reaches a second set increase value, the high-speed abrasive flow polishing operation is stopped;

[0080] Step 8: Use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium in the inner flow channel of the workpiece, and then use ultrasonic immersion to clean the inner flow channel of the workpiece. After cleaning, rinse with pure water several times and then dry.

[0081] First, the fine inner flow channel is lightly polished, locally chamfered and micro-shaped using water-based two-phase flow, which significantly improves the permeability of the inner flow channel to chemical polishing liquid and high-speed abrasive flow fluid polishing media; then, a chemical polishing process is used to further remove the powder and particles remaining in the inner flow channel after water-based two-phase flow polishing, further improve the permeability of the inner flow channel to high-speed abrasive flow fluid polishing media and reduce the initial roughness difference between the upper and lower surfaces of the additively manufactured inner flow channel. On this basis, high-speed abrasive flow polishing is finally used to achieve uniform polishing of the upper and lower surfaces of the inner flow channel and its corners and achieve a higher surface polishing quality.

[0082] The third setting of the increase value is 5% to 15%. Water-based two-phase flow and high-speed abrasive flow belong to the same working condition fluid dynamic polishing method. The local sharp edge chamfering and micro-shaping of the fine inner flow channel by water-based two-phase flow will significantly improve the fluid permeability of the subsequent chemical polishing liquid and high-speed abrasive flow polishing medium, and improve its polishing efficiency. After water-based two-phase flow polishing, the increase of the flow rate of the inner flow channel by more than 15% will lead to excessive differences between the upper and lower surfaces and the inside and outside of the turns. The increase of the flow rate below 5% will not have a significant impact on the fluid permeability and polishing efficiency of the subsequent chemical polishing liquid and high-speed abrasive flow polishing medium.

[0083] Furthermore, a high-speed water-based two-phase flow medium is prepared by using deionized water, aluminum oxide and rosin resin emulsion.

[0084] In the present invention, the chemical polishing liquid is prepared by deionized water, hydrochloric acid, nitric acid, ferric chloride, cerium oxide and sodium molybdate. The specific ingredients are shown in Table 1.

[0085] Table 1 Preferred chemical polishing liquid formula for nickel-based high-temperature alloys

[0086] Element HCl(ml) <![CDATA[HNO 3( ml)]]> <![CDATA[FeCl 3( g)]]> <![CDATA[CeO 2( g)]]> NaMoO(g) <![CDATA[H 2 O(ml)<!-- 5 --> ]]> content 10～35 2～6 10～20 2～5 3～8 10～25

[0087] Among them, HCl and HNO are preferred 3 The main corrosion effect is that, through engineering tests, it is known that for nickel-based high-temperature alloys, HCl and HNO 3 It can achieve good oxidation and dissolution effects (thinning amount is 0.8mm / 30min), and the oxidation and dissolution reagents can also be selected as H 2 SO 4 , HF, BH 3 O 3 HClO 4 , HI, HBr, HIO 3 , H 3 PO 4 etc.; the catalyst is preferably FeCl 3 The reason is that FeCl 3 As a catalyst, it can greatly increase the reaction rate by about 70% to 75%. Other catalysts can be iron powder, MnO 2 、Al 2 O 3 , Fe 2 O 3 、CuO、AlCl 3 etc.; NaMoO is preferred as the film-forming agent because NaMoO\ as a film-forming agent can effectively prevent the nickel-based high-temperature alloy from being over-corroded and forming corrosion pits. Using NaMoO as a film-forming agent can significantly reduce the number of chemical corrosion pits by about 80% to 85%, significantly alleviating the pitting degree and corrosion layer depth of the polishing liquid on the nickel-based high-temperature alloy. NaHO 3 、Na 2 CrO 4 、As 2 O 3 、SbCl 3 、Na 2 SiO 3 In addition, compared with the traditional nickel-based high-temperature alloy chemical polishing solution, the unique addition of CeO 2When the inner flow channel is small or long, the bubbles generated by the chemical reaction will make the flow channel contain less corrosive solution, and the efficiency of chemical polishing will be very low. 2 The components can accelerate the dissolution rate of chemical reaction bubbles in the polishing liquid, thereby improving the polishing rate of the chemical polishing liquid on the fine inner flow channel of the nickel-based high-temperature alloy.

[0088] During the chemical polishing process, the chemical polishing liquid needs to flow in the fine inner flow channel for polishing, and the set flow rate of the chemical polishing liquid is 0.5-2m / s. Even if the polishing liquid is stirred, vibrated or ultrasonically assisted, the fine inner flow channel still contains very little fresh polishing liquid, and the efficiency of chemical reaction and polishing is very low, and even polishing cannot be performed due to the blockage of local reaction bubbles in the fine inner flow channel. The bubbles generated by the chemical reaction are taken out of the fine inner flow channel by the rapid flow of the polishing liquid, thereby increasing the contact area between the polishing liquid and the surface of the inner flow channel. In addition, the fresh polishing liquid is continuously introduced into the circulation to quickly discharge the locally ineffective polishing liquid, thereby increasing the chemical reaction rate and polishing efficiency. Through engineering experiments, it is known that if the flow rate of the polishing liquid in the inner flow channel is lower than 0.5m / s, the bubbles generated by the chemical polishing liquid in the fine inner flow channel and the ineffective polishing liquid cannot be quickly removed and discharged by the flow field, resulting in reduced efficiency of chemical reaction and polishing or even inability to polish. In addition, when the flow rate of the polishing liquid in the inner flow channel is higher than 2m / s, the chemical reaction time between the chemical polishing liquid and the high-temperature alloy material is too short, which will also cause the chemical reaction to not be fully completed in time, and then reduce the efficiency of chemical polishing or even make polishing impossible. Therefore, the flow rate of the chemical polishing liquid is 0.5-2m / s. The chemical reaction between the chemical polishing liquid and the metal material can be fully completed, and the bubbles and invalid polishing liquid generated by the reaction of the chemical polishing liquid in the fine inner flow channel can be effectively discharged without affecting the chemical polishing efficiency. The smaller the diameter of the fine inner flow channel, the larger the aspect ratio, and the more local turning deformation features, the higher the flow rate of the chemical polishing liquid needs to be.

[0089] Preferably, the present invention uses the flow change of chemical polishing liquid through the fine inner flow channel as the online monitoring method and effect evaluation standard of chemical polishing. The front chemical polishing reaction is excessive, the corrosion layer is too deep, and the back high-speed abrasive flow polishing cannot fully remove the corrosion layer and defect layer generated by the front chemical polishing. The front chemical polishing reaction is insufficient, and it is impossible to achieve sufficient floating powder removal for additive manufacturing, and it is impossible to significantly reduce the surface sintering or semi-sintering particle size after printing, and it is impossible to significantly reduce the difference in roughness of the upper and lower surfaces and the inner and outer sides of the turning. It is not enough to improve the passability of the back high-speed abrasive flow polishing medium through the fine inner flow channel, resulting in the high-speed abrasive flow polishing medium still being difficult to achieve uniform polishing through the fine inner flow channel with a diameter of 1.5mm to 3mm and an aspect ratio of ≥50:1. The polishing medium is easy to be blocked at the bends and dead corners of the fine inner flow channel. Forcing it through will cause the flow channel to deform or even crack. In addition, since the solution components, solution temperature and solution volume of the chemical polishing process will be continuously consumed and dynamically changed with the chemical reaction and the natural placement of the polishing liquid, the effect of each chemical polishing at the same chemical polishing time and temperature is inconsistent. For the fine inner flow channel, it is proposed to use the flow monitoring value of the polishing liquid flowing through the fine inner flow channel during the reaction process as the basis for the chemical polishing standard. The reason is that no matter how the chemical solution changes with the reaction or natural placement during chemical polishing, the flow rate or flow resistance change of the chemical polishing liquid in the fine inner flow channel can reflect the final effect of chemical polishing, because the essence of the increase in flow rate or flow resistance is the final removal amount of high-temperature alloy materials under chemical polishing, and the final removal amount of materials in chemical polishing can characterize the final reaction amount of the chemical reaction, which has nothing to do with the intermediate process of the chemical reaction, and has nothing to do with the changes in factors such as the polishing liquid component, temperature, concentration, volume and placement time.

[0090] During chemical polishing, the depth of the chemical corrosion layer should be controlled between 100 μm and 200 μm, and the flow rate of the chemical polishing liquid in the fine inner flow channel during chemical polishing should be increased by 15% to 50% (the first set increase value).

[0091] When the chemical corrosion depth is less than 100μm, chemical polishing does not improve the flow rate of the fine inner flow channel enough, the degree of chemical reaction, that is, the amount of metal material removed by chemical reaction, is insufficient, the surface roughness improvement and the patency of the flow channel are still low, and the subsequent high-speed abrasive flow polishing medium is still difficult to pass through the fine inner flow channel, resulting in low efficiency of high-speed abrasive flow polishing or even inability to polish. When the chemical corrosion depth is greater than 200μm, the chemical corrosion layer and defect layer will be too deep, and the subsequent high-speed abrasive flow will be difficult to fully remove the remaining corrosion layer and defect layer. Specifically, the data relationship between the depth of the chemical polishing corrosion layer and the increase in the flow rate of the fine inner flow channel is shown in Table 2.

[0092] Table 2 Depth of corrosion layer on the surface of the inner flow channel after chemical polishing and the corresponding flow rate increase data

[0093]

[0094] Furthermore, a soaking liquid for soaking and cleaning workpieces is prepared by using 2% to 6% of synthetic fatty acid monoethanolamide polyalkoxy ether, 1% to 3% of alkyl polyoxyethylene ether phosphate salt, 24% to 30% of sodium metasilicate, 24% to 28% of sodium tripolyphosphate and 10% of sodium carbonate.

[0095] In the high-speed abrasive flow polishing stage, since the polishing effect of the fine inner flow channel during the high-speed abrasive flow polishing process cannot be observed and measured by direct visualization methods, the unique viscous polishing medium of the high-speed abrasive flow cannot be detected by traditional fluid flow methods. The present invention uses the mass / weight flow rate of the polishing medium flowing out of the inner flow channel per unit time as the online monitoring and evaluation standard for the high-speed abrasive flow polishing effect of the fine inner flow channel, and measures and characterizes the flow rate of the high-speed abrasive flow polishing medium by mass balance weighing method.

[0096] Specifically, for fine inner flow channels with a diameter of 1.5 mm to 3 mm and an aspect ratio of ≥50:1, the preferred flow rate of the high-speed abrasive flow polishing medium is in the range of 10 to 25 g / min. If the flow rate of the high-speed abrasive flow polishing medium is too low, the polishing medium cannot achieve sufficient permeability, pressure and flow rate for the fine inner flow channel, resulting in very low efficiency of high-speed abrasive flow polishing or even failure to polish. If the flow rate of the high-speed abrasive flow polishing medium is too high, over-polishing deformation will still occur at the turning point due to the direct impact of the wall surface by the fluid flow rate being too fast. The polishing medium flow rate increases with the decrease in the diameter of the inner flow channel, the increase in the aspect ratio and the increase in the local turning deformation characteristics. Specifically, the data relationship between the preferred values ​​of fine inner flow channels of different diameters and the flow rate of high-speed abrasive flow polishing media is shown in Table 3.

[0097] Table 3 Optimal values ​​of high-speed abrasive polishing medium flow rates for micro-inner flow channels of different diameters

[0098] Inner channel diameter (mm) 2.5～3 2～2.5 1.5～2 High-speed abrasive outflow rate (g / min) 20～25 14～18 10～13

[0099] In the embodiment of the present invention, for a fine inner flow channel with a diameter of 1.5 mm to 3 mm and an aspect ratio of ≥50:1, the viscosity range of the high-speed abrasive flow polishing medium is 1000 cP to 8000 cP. The viscosity of the polishing medium decreases as the diameter of the inner flow channel decreases, the aspect ratio increases, and the local turning deformation features become more numerous. The reason is that when the diameter of the fine inner flow channel is smaller, the aspect ratio is larger, and the local turning deformation features are more numerous, the passability of the high-speed abrasive flow polishing medium will be worse, resulting in a decrease in polishing efficiency or even inability to polish. Therefore, it is necessary to reduce the viscosity of the high-speed abrasive flow polishing medium accordingly to improve the passability of the fine inner flow channel, thereby improving the polishing efficiency. However, the viscosity of the high-speed abrasive flow polishing medium should not be too low. If the viscosity is too low, the extrusion force of the polishing medium on the wall of the inner flow channel will be reduced, resulting in a decrease in polishing efficiency. At the same time, it is also easy to cause the polishing medium to be blocked due to the "sticky wall effect", and it will also reduce the binding effect of the polishing medium on the abrasive particles therein, resulting in over-polishing, deformation and aggravation of the difference in roughness between the upper and lower surfaces at the turning points of the inner flow channel. Specifically, the viscosity of the high-speed abrasive flow polishing medium corresponding to the fine inner flow channels of different calibers is shown in Table 4.

[0100] Table 4 High-speed abrasive flow polishing medium viscosity corresponding to micro-inner flow channels with different diameters

[0101] Inner channel diameter (mm) 2.5～3 2～2.5 1.5～2 Viscosity(cP) 6000～8000 5000～6000 3000～5000

[0102] Preferably, the viscosity of the high-speed abrasive flow polishing medium is regulated by adding ethylene-propylene branched copolymer to the high-speed abrasive flow polishing medium because the ethylene-propylene branched copolymer has better solubility and high temperature stability in the high-speed abrasive flow polishing medium.

[0103] In the high-speed abrasive flow polishing stage, for the fine inner flow channel with a diameter of 1.5mm to 3mm and an aspect ratio of ≥50:1, the abrasive particle size of the high-speed abrasive flow medium ranges from 60 to 1200 mesh. And the abrasive particle size of the high-speed abrasive flow polishing medium gradually decreases with the decrease of the diameter of the fine inner flow channel, the increase of the aspect ratio and the increase of the local turning deformation characteristics. The reason is that when the diameter of the fine inner flow channel becomes smaller, the aspect ratio increases and the local turning deformation characteristics become more and more, the passability of the high-speed abrasive flow polishing medium becomes worse, resulting in a decrease in polishing efficiency or even inability to polish. Therefore, it is necessary to be lower than the upper limit of the abrasive particle size to ensure the passability of the high-speed abrasive flow polishing medium, thereby avoiding the decrease in the fluidity of the polishing medium or even blocking and cracking the inner flow channel. However, the abrasive particle size of the high-speed abrasive flow polishing medium should not be too low. Too small abrasive particle size will reduce the effective friction area on the wall of the inner flow channel and lead to a decrease in polishing efficiency. Specifically, the data relationship between fine inner flow channels of different diameters and abrasive particle sizes is shown in Table 5.

[0104] Table 5 Corresponding abrasive particle sizes of micro-inner flow channels with different diameters

[0105]

[0106] The set threshold in the embodiment of the present invention is 30Mpa.

[0107] Specifically, for the fine inner flow channel with a diameter of 1.5mm to 3mm and an aspect ratio of ≥50:1, a hydraulic thrust greater than 30Mpa is preferably provided to the high-speed abrasive flow polishing medium. The hydraulic thrust of the high-speed abrasive flow increases with the decrease in the diameter of the fine inner flow channel, the increase in the aspect ratio, and the increase in the local turning deformation characteristics. The reason is that for the fine inner flow channel with a diameter of 1.5mm to 3mm and an aspect ratio of ≥50:1, it is necessary to provide a hydraulic thrust greater than 30Mpa to the high-speed abrasive flow polishing medium to ensure the high-speed passability and polishing efficiency of the polishing medium to the fine inner flow channel. This pressure exceeds the hydraulic thrust range of the traditional abrasive flow (0.7MPa-22.4MPa). It should be pointed out that processing can also be achieved using the traditional abrasive flow pressure range (0.7MPa-22.4MPa), but the efficiency is low. Specifically, the data relationship between the fine inner flow channels of different diameters and the driving pressure of the high-speed abrasive flow equipment is shown in Table 6.

[0108] Table 6 High-speed abrasive flow hydraulic thrust corresponding to micro-inner flow channels with different diameters

[0109]

[0110]

[0111] Furthermore, the second set improvement value is 15% to 60%. When the discharge mass flow rate of the high-speed abrasive flow polishing medium through the fine inner flow channel is increased by 15% to 30%, the roughness of the surface of the inner flow channel of the workpiece is reduced by about one time, when the discharge mass flow rate is increased by 30% to 50%, the roughness of the surface of the inner flow channel of the workpiece is reduced by about two times, and when the discharge mass flow rate is increased by more than 50%, the roughness of the surface of the inner flow channel of the workpiece is reduced by about three times. The reason is that the higher the discharge mass of the high-speed abrasive flow polishing medium through the fine inner flow channel is improved, the better the passability of the inner flow channel surface to the high-speed abrasive flow polishing medium is, and at this time, the lower the surface roughness of the fine inner flow channel, the higher the surface quality, and the more fully the surface particles, powder and steps are removed.

[0112] like Figure 2 As shown, the present invention also provides a chemical polishing liquid device, which is used for the chemical polishing operation in the above-mentioned additive manufacturing fine and complex internal flow channel finishing method, and the chemical polishing liquid device includes:

[0113] A chemical polishing liquid container 1, used for placing a chemical polishing liquid 11;

[0114] The chemical polishing liquid recovery device 10 is spaced apart from the chemical polishing liquid container 1 , and the chemical polishing liquid recovery device 10 is connected to the chemical polishing liquid container 1 through a guide pipe and a return pipe, and the workpiece 5 is arranged in the guide pipe.

[0115] Furthermore, the diversion pipeline includes:

[0116] A diversion pump 3 is arranged in the chemical polishing liquid container 1;

[0117] The inlet of the valve 4 is connected to the outlet of the diversion pump 3, and the outlet of the valve 4 is connected to the inlet of the workpiece 5;

[0118] The inlet of the flow meter 6 is connected to the outlet of the workpiece 5 , and the outlet of the flow meter 6 is connected to the chemical polishing liquid recovery device 10 through the first flow guide pipe 7 .

[0119] The reflux pipeline includes a reflux pump 12 and a second guide pipe 13. The reflux pump 12 is arranged in the chemical polishing liquid recovery device 10. One end of the second guide pipe 13 is connected to the outlet of the reflux pump 12, and the other end of the second guide pipe 13 is connected to the chemical polishing liquid container 1.

[0120] It should be noted that the chemical polishing liquid container 1, the first guide tube 7, the second guide tube 13, and the chemical polishing liquid recovery device 10 are all made of polytetrafluoroethylene material, which has strong acid resistance and high temperature resistance.

[0121] Preferably, a constant temperature heating device 2 is also provided in the chemical polishing liquid container 1. The surface of the constant temperature heating device 2 is coated with an anti-corrosion coating, and the chemical polishing liquid 11 can be preheated to the set temperature when in use. The surfaces of the diversion pump 3 and the reflux pump 12 are coated with an anti-corrosion coating. The diversion pump 3 is used to press the chemical polishing liquid 11 into the inner flow channel of the workpiece 5 through the first diversion pipe 7, and the reflux pump 12 is used to return the chemical polishing liquid 11 in the chemical polishing liquid recovery device 10 to the chemical polishing liquid container 1 for recycling until the corrosive acid in the chemical polishing liquid 11 is exhausted.

[0122] The valve 4 is switch-controlled and made of polypropylene material, which is acid-resistant. The flow meter 6 (the flow meter has a pressure rating of 5 MPa, polytetrafluoroethylene lining, is corrosion-resistant, and can be widely used in the chemical industry) monitors the flow rate of the chemical polishing liquid 11 at the outlet of the workpiece 5 in real time.

[0123] Furthermore, the embodiment of the present invention also includes a tool 9, which is arranged in the guide pipe and is used to clamp the workpiece 5. A sealing component 8 is also arranged at each location where sealing is required. The sealing component 8 is made of fluororubber material to prevent leakage of the chemical polishing liquid 11. At the same time, when the chemical polishing liquid 11 flowing through the flow channel in the workpiece 5 is collected in the chemical polishing liquid recovery device 10, the sealing by the sealing component 8 can prevent environmental pollution.

[0124] The following is an example of an embodiment for illustration, which is as follows:

[0125] Example 1: This example is the finishing of two inner flow channel samples with a two-dimensional turning structure. The inner flow channel to be finished adopts laser additive manufacturing technology. The diameter D of the micro inner flow channel is about 1.5mm, the total length of the flow channel is about 80mm, and the aspect ratio is about greater than 50:1. Each flow channel includes two turning structures. The material is a high-temperature alloy. The original roughness Ra of the outer side of the inner flow channel turn is 10.3μm, and the original roughness Ra of the inner side of the turn is 8.1μm. The specific processing method is as follows:

[0126] Step 1: Perform high-speed water-based two-phase flow polishing. The high-speed water-based two-phase flow consists of deionized water, aluminum oxide, and tackifier rosin resin emulsion. The viscosity is 180cP, the aluminum oxide abrasive particle size is 43μm, the abrasive mass concentration is 30g / L, the plunger pump thrust is 53MPa, and the initial flow rate is 3.5L / min. When the high-speed water-based two-phase flow rate increases by 8%, polishing is stopped.

[0127] Step 2: Prepare 5L of chemical polishing solution. The order and amount of adding each substance are as follows: 2 O (2L), HCl (2.5L), HNO 3 (0.5L), FeCl 3 (0.76kg), CeO 2 (0.15kg), NaMoO (0.23kg).

[0128] Step 3: Pour the chemical polishing liquid prepared in the second step into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to 50°C.

[0129] Step 4: Adjust the pump pressure of the flow guide pump in the chemical polishing device, read the flow value of the chemical polishing liquid flowing out of the fine inner flow channel at the beginning through the flow meter, and divide the flow value by the cross-sectional area of ​​the inner flow channel to obtain the starting flow rate of the chemical polishing medium. When the flow rate of the chemical polishing liquid flowing through the inner flow channel is adjusted to 1m / s by the pump, start chemical polishing. After a period of processing, stop chemical polishing when the flow rate of the chemical polishing liquid increases by 50%.

[0130] Step 5: Use ultrasonic immersion to clean the flow channel inside the workpiece. The immersion liquid is an alkaline cleaning agent that neutralizes the residual acidic polishing liquid. The material ratio is: synthetic fatty acid monoethanolamide polyalkoxy ether 2% to 6%, alkyl polyoxyethylene ether phosphate ester salt 1% to 3%, sodium metasilicate 24% to 30%, sodium tripolyphosphate 24% to 28%, sodium carbonate 10%. Then rinse with pure water several times and finally dry for use.

[0131] Step 6: Select the viscosity of the high-speed abrasive flow polishing medium. Since the workpiece diameter is 1.8mm, the viscosity of the high-speed abrasive flow polishing medium is adjusted to 4000cP.

[0132] Step 7: Select the abrasive particle size of the high-speed abrasive flow polishing medium. Since the workpiece diameter is 1.8mm, the abrasive particle size of the high-speed abrasive flow polishing medium is selected to be 600 mesh.

[0133] Step 8: Adjust the high-speed abrasive flow hydraulic thrust. When the mass flow rate reaches 13g / min by adjusting the hydraulic thrust, start high-speed abrasive flow polishing. Process for a period of time under this hydraulic thrust. When it is monitored that the discharge mass flow rate of the high-speed abrasive flow polishing medium at the outlet of the fine inner flow channel increases by 60%, stop processing.

[0134] Step 9: First use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium inside the fine inner flow channel, then use ultrasonic immersion cleaning, and then rinse with pure water several times and then dry.

[0135] like Figure 3 As shown in the figure, the two inner flow channel samples with a turning structure after three-fold composite finishing were cut, and the inner surface of the flow channel can be clearly seen to be flattened and smooth and bright, close to the machined surface. The metallographic test showed that there was no residual, embedded or semi-sintered additive manufacturing powder. The roughness test showed that the outer side of the turn had a roughness of Ra = 0.8μm, and the inner side of the spiral turn had a roughness of Ra = 0.7μm, reaching the target requirements of Ra < 1.6μm and a roughness difference of < 15% between the inner and outer sides of the turn.

[0136] Example 2: This example is the finishing of a two-dimensional O-shaped inner flow channel sample. The inner flow channel to be finished is manufactured using laser additive manufacturing technology. The structure is a fine inner flow channel with a diameter D = 1.5 mm, a total flow channel length = 160 mm, an aspect ratio of about greater than 100:1, an O-shaped bend structure, and a material of high-temperature alloy. The original roughness Ra of the inner flow channel is about 7.4 (non-overhanging surface) ~ 11.3 μm (overhanging surface). The specific processing method is as follows:

[0137] Step 1: Perform high-speed water-based two-phase flow polishing. The high-speed water-based two-phase flow consists of deionized water, aluminum oxide, and tackifier rosin resin emulsion. The viscosity is 150cP, the aluminum oxide abrasive particle size is 43μm, the plunger pump thrust is 63MPa, and the initial flow rate is 2.8L / min. When the high-speed water-based two-phase flow rate increases by 12%, polishing is stopped.

[0138] Step 2: Prepare 5L of chemical polishing solution. The order and amount of adding each substance are as follows: 2 O (2L), HCl (2.5L), HNO 3 (0.5L), FeCl 3 (0.76kg), CeO2 (0.15kg), NaMoO (0.23kg).

[0139] Step 3: Pour the chemical polishing liquid prepared in the second step into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to 50°C.

[0140] Step 4: Adjust the pump pressure of the flow pump in the chemical polishing device, read the flow value of the chemical polishing liquid flowing out of the fine inner flow channel at the beginning through the flow meter, and divide the flow value by the cross-sectional area of ​​the inner flow channel to get the starting flow rate of the chemical polishing medium. When the flow rate is adjusted to 1.5m / s by the flow pump, start chemical polishing. After a period of processing, stop chemical polishing when the flow rate of the chemical polishing liquid increases by 50%.

[0141] Step 5: Use ultrasonic immersion to clean the flow channel inside the workpiece. The immersion liquid is an alkaline cleaning agent that neutralizes the residual acidic polishing liquid. The material ratio is: synthetic fatty acid monoethanolamide polyalkoxy ether 2% to 6%, alkyl polyoxyethylene ether phosphate ester salt 1% to 3%, sodium metasilicate 24% to 30%, sodium tripolyphosphate 24% to 28%, sodium carbonate 10%. Then rinse with pure water several times and finally dry for use.

[0142] Step 6: Select the viscosity of the high-speed abrasive flow polishing medium. Since the workpiece diameter is 1.5mm, the viscosity of the high-speed abrasive flow polishing medium is 4000cP.

[0143] Step 7: Select the abrasive particle size of the high-speed abrasive flow polishing medium. Since the workpiece diameter is 1.5mm, the abrasive particle size of the high-speed abrasive flow polishing medium is 600 mesh.

[0144] Step 8: Adjust the high-speed abrasive flow hydraulic thrust. When the mass flow rate reaches 12g / min by adjusting the hydraulic thrust, start high-speed abrasive flow polishing. Process for a period of time under this hydraulic thrust. When it is monitored that the discharge mass flow rate of the high-speed abrasive flow polishing medium at the outlet of the fine inner flow channel increases by 60%, stop processing.

[0145] Step 9: First use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium inside the fine inner flow channel, then use ultrasonic immersion cleaning, and then rinse with pure water several times and then dry.

[0146] like Figure 4 and Figure 5As shown in the figure, the two-dimensional O-shaped inner flow channel sample after three-fold composite finishing was cut, and the inner surface of the flow channel can be clearly seen to be flattened and smooth and bright, close to the machined surface. The metallographic test showed that there was no residual, embedded and semi-sintered additive manufacturing powder. The roughness test showed that the overhanging surface of the O-shaped inner flow channel had a roughness of Ra = 1.5μm, and the non-overhanging surface had a roughness of Ra = 1.4μm, reaching the target requirement of roughness Ra < 1.6μm and the roughness difference of the upper and lower surfaces with large original differences after polishing was < 15%.

[0147] The above is only a specific embodiment of the present invention, and cannot be used to limit the scope of the invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the patent of the present invention, should still fall within the scope of this patent. In addition, the technical features of the present invention can be freely combined with each other, with each other, and with each other.

Claims

1. A finishing method for additive manufacturing of fine and complex internal flow channels, characterized in that: The following steps are involved: Step 1: Prepare chemical polishing solution; Step 2: Pour the prepared chemical polishing liquid into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to a set temperature; Step 3, adjusting the pump pressure of the chemical polishing liquid container, reading the flow value of the chemical polishing liquid flowing out of the inner flow channel of the workpiece at the beginning, and calculating the starting flow rate of the chemical polishing liquid; starting the polishing operation when adjusting the flow rate of the chemical polishing liquid to the set flow rate, and stopping the chemical polishing operation when the flow rate of the chemical polishing liquid increases to the first set increase value; Step 4: Use ultrasonic immersion to clean the inner flow channel of the workpiece. After the cleaning is completed, rinse it with pure water several times and then dry it; Step 5: Select the viscosity and abrasive particle size of the high-speed abrasive flow polishing medium; Step 6: Adjust the high-speed abrasive flow hydraulic thrust. When the mass flow is greater than the set threshold value through the hydraulic thrust adjustment, the high-speed abrasive flow polishing operation is started; when it is monitored that the discharge mass flow of the high-speed abrasive flow polishing medium at the outlet of the inner flow channel of the workpiece reaches a second set increase value, the high-speed abrasive flow polishing operation is stopped; Step 7: Use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium in the inner flow channel of the workpiece, and then use ultrasonic immersion to clean the inner flow channel of the workpiece. After cleaning, rinse with pure water several times and then dry.

2. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 1, characterized in that: The step 1 specifically comprises: preparing a chemical polishing solution by using deionized water, hydrochloric acid, nitric acid, ferric chloride, cerium oxide and sodium molybdate.

3. The finishing method for additively manufacturing a fine and complex inner flow channel according to claim 1, characterized in that: The step three is specifically as follows: The set flow rate of the chemical polishing liquid is 0.5-2 m / s; The first set boost value is 15% to 50%.

4. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 1, characterized in that: The step three also includes controlling the depth of the chemical etching layer to be between 100 μm and 200 μm during the chemical polishing operation.

5. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 1, characterized in that: In the step 4, a soaking liquid for soaking and cleaning the workpiece is prepared by using synthetic fatty acid monoethanolamide polyalkoxy ether, alkyl polyoxyethylene ether phosphate salt, sodium metasilicate, sodium tripolyphosphate and sodium carbonate.

6. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 1, characterized in that: In the step 5, the viscosity of the high-speed abrasive flow polishing medium is in the range of 1000 cP to 8000 cP, and the abrasive particle size is in the range of 60 to 1200 meshes.

7. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 6, characterized in that: The step five also includes: adjusting the viscosity of the high-speed abrasive flow polishing medium by adding ethylene-propylene branched copolymer into the high-speed abrasive flow polishing medium.

8. The finishing method for additively manufacturing a fine and complex internal flow channel according to claim 1, characterized in that: The set threshold in step six is ​​30Mpa.

9. The finishing method for additively manufacturing a fine and complex internal flow channel according to claim 1, characterized in that: The second set increase value in step six is ​​15% to 60%.

10. A finishing method for additive manufacturing of fine and complex internal flow channels, characterized in that: The following steps are involved: Step 1: Perform high-speed water-based two-phase flow polishing on the inner flow channel of the workpiece, and stop the high-speed water-based two-phase flow polishing when the flow rate of the high-speed water-based two-phase flow medium reaches a third set increase value; Step 2: preparing chemical polishing solution; Step 3: Pour the prepared chemical polishing liquid into the chemical polishing liquid container, and start the constant temperature heating device to heat the chemical polishing liquid to the set temperature; Step 4, adjusting the pump pressure of the chemical polishing liquid container, reading the flow value of the chemical polishing liquid flowing out of the inner flow channel of the workpiece at the beginning, and calculating the starting flow rate of the chemical polishing liquid; starting the polishing operation when adjusting the flow rate of the chemical polishing liquid to the set flow rate, and stopping the chemical polishing operation when the flow rate of the chemical polishing liquid increases to the first set increase value; Step 5: Use ultrasonic immersion to clean the inner flow channel of the workpiece. After the cleaning is completed, rinse it with pure water several times and then dry it; Step 6: Select the viscosity and abrasive particle size of the high-speed abrasive flow polishing medium; Step 7, adjusting the high-speed abrasive flow hydraulic thrust, when the mass flow is greater than the set threshold value through the hydraulic thrust adjustment, the high-speed abrasive flow polishing operation is started; when it is monitored that the discharge mass flow of the high-speed abrasive flow polishing medium at the outlet of the inner flow channel of the workpiece reaches a second set increase value, the high-speed abrasive flow polishing operation is stopped; Step 8: Use a high-pressure air gun to blow out the high-speed abrasive flow polishing medium in the inner flow channel of the workpiece, and then use ultrasonic immersion to clean the inner flow channel of the workpiece. After cleaning, rinse with pure water several times and then dry.

11. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 10, characterized in that: A high-speed water-based two-phase flow medium is prepared by using deionized water, alumina and rosin resin emulsion.

12. The finishing method for additively manufacturing a fine and complex inner flow channel according to claim 10, characterized in that: The step 2 specifically comprises: preparing a chemical polishing solution by using deionized water, hydrochloric acid, nitric acid, ferric chloride, cerium oxide and sodium molybdate.

13. The finishing method for additively manufacturing a fine and complex inner flow channel according to claim 10, characterized in that: The step 4 is specifically as follows: The set flow rate of the chemical polishing liquid is 0.5-2 m / s; The first set boost value is 15% to 50%.

14. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 10, characterized in that: The step 4 also includes controlling the depth of the chemical etching layer to be between 100 μm and 200 μm during the chemical polishing operation.

15. The finishing method for additively manufacturing a fine and complex inner flow channel according to claim 10, characterized in that: In the step 5, a soaking liquid for soaking and cleaning the workpiece is prepared by using synthetic fatty acid monoethanolamide polyalkoxy ether, alkyl polyoxyethylene ether phosphate salt, sodium metasilicate, sodium tripolyphosphate and sodium carbonate.

16. The finishing method for additively manufacturing a fine and complex inner flow channel according to claim 10, characterized in that: In step six, the viscosity of the high-speed abrasive flow polishing medium is in the range of 1000 cP to 8000 cP, and the abrasive particle size is in the range of 60 to 1200 meshes.

17. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 16, characterized in that: The step six also includes: adjusting the viscosity of the high-speed abrasive flow polishing medium by adding ethylene-propylene branched copolymer into the high-speed abrasive flow polishing medium.

18. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 10, characterized in that: The threshold value in step seven is set to 30 MPa.

19. The finishing method for additive manufacturing of fine and complex internal flow channels according to claim 10, characterized in that: The second set boost value in step seven is 15% to 60%.

20. A chemical polishing liquid device, used for chemical polishing operation in the finishing method of additive manufacturing of fine and complex internal flow channels according to any one of claims 1 to 19, characterized in that: The chemical polishing liquid device includes: A chemical polishing liquid container (1), used for placing a chemical polishing liquid (11); The chemical polishing liquid recovery device (10) is arranged at a distance from the chemical polishing liquid container (1), and the chemical polishing liquid recovery device (10) is connected to the chemical polishing liquid container (1) via a guide pipe and a return pipe, and the workpiece (5) is arranged in the guide pipe.

21. The chemical polishing liquid device according to claim 20, characterized in that: The flow guide pipeline comprises: A diversion pump (3) is arranged in the chemical polishing liquid container (1); A valve (4), the inlet of which is connected to the outlet of the diversion pump (3), and the outlet of the valve (4) is connected to the inlet of the workpiece (5); The inlet of the flow meter (6) is connected to the outlet of the workpiece (5), and the outlet of the flow meter (6) is connected to the chemical polishing liquid recovery device (10) through the first flow guide pipe (7).

22. The chemical polishing liquid device according to claim 21, characterized in that: The reflux pipeline comprises a reflux pump (12) and a second flow guide pipe (13); the reflux pump (12) is arranged in a chemical polishing liquid recovery device (10); one end of the second flow guide pipe (13) is connected to the outlet of the reflux pump (12); and the other end of the second flow guide pipe (13) is connected to a chemical polishing liquid container (1).

23. The chemical polishing liquid device according to claim 20, characterized in that: A constant temperature heating device (2) is also provided in the chemical polishing liquid container (1).

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