An additive manufacturing internal flow channel polishing system and method

Abstract

The application belongs to the polishing technical field, and provides an additive manufacturing inner flow channel polishing system, which comprises an electrolyte pool located in a water bath pool; a pump, the electrolyte pool, a cleaning pool and an acid pickling pool are connected with the input end of the pump through connecting pipes respectively, the output end of the pump is connected with one end of an inner flow channel in a workpiece through a connecting pipe, the other end of the inner flow channel is connected with the electrolyte pool, the cleaning pool and the acid pickling pool through connecting pipes respectively; a direct current power supply, the negative electrode of the direct current power supply is connected with a cathode through a first wire, the cathode is immersed in the electrolyte pool, and the positive electrode of the direct current power supply is connected with the workpiece. The application also provides an additive manufacturing inner flow channel polishing method. The electrolyte pool is arranged, electrolyte is only passed into the inner flow channel to be polished during polishing operation, the electrolytic polishing process is limited to the inner flow channel area to be polished, and the electrically conductive clamp is clamped at multiple positions of the shell, so that the uniformity of electrolysis is improved.

Description

Technical Field

[0001] This invention belongs to the field of polishing technology, and particularly relates to an additive manufacturing internal flow channel polishing system and polishing method. Background Technology

[0002] Metal additive manufacturing uses metal powder as raw material. Based on the layered slicing information of the 3D CAD model of the part, it performs layer-by-layer laser scanning and melting to ultimately form the entire 3D model. It is suitable for manufacturing complex curved internal flow channels that cannot be processed by traditional subtractive manufacturing, such as engines, forming chambers, and molds containing complex cooling channels. For complex curved internal flow channels, low flow resistance is usually required, so there are certain requirements for surface finish. Typically, the surface roughness Ra should not exceed 5μm. However, the surface roughness of internal flow channels printed by SLM (Selective Laser Melting) technology is usually around Ra 12-20μm, and the surface roughness problem of the internal flow channels must be solved by subsequent polishing.

[0003] Polishing methods for internal flow channels include chemical etching, abrasive flow, electrochemistry, water jetting, and electrical discharge machining (EDM). However, each method has its limitations: water jetting cannot handle high-strength alloy materials, such as high-temperature alloys and mold steel; EDM and conventional electrochemical methods can only handle the inner surfaces of straight pipes and cannot handle the inner surfaces of complex curved flow channels; pure chemical etching easily damages the chemical state of the metal surface, especially the anti-corrosion layer structure, leading to easy rust problems later; abrasive flow polishing is a better method for polishing internal flow channels. Abrasive flow polishing involves abrasive particles suspended in a viscoelastic semi-solid medium flowing back and forth at high speed over the surface of the part to be polished under a certain extrusion pressure, producing a grinding effect to remove trace metals, thereby achieving the polishing effect. However, the use of abrasive flow equipment often requires the design of special fixtures according to different product structures, and the effect on small, complex, and curved pipes is not good.

[0004] Electropolishing is an effective method for polishing metals such as stainless steel. It utilizes the principle that microscopic protrusions on the metal surface undergo anodic dissolution in a specific electrolyte and at an appropriate current density, which can quickly remove surface defects such as burrs and achieve the purpose of polishing. However, the electropolishing process in the usual sense involves immersing the part of the workpiece to be polished in the electrolyte as the anode and polishing it at a certain current density. In this process, the outer surface of the workpiece is also corroded in the internal flow channel of the electropolishing process. Moreover, since the resistance between the outer surface and the cathode is lower, its corrosion rate is much higher than that of the internal flow channel. Summary of the Invention

[0005] The purpose of this invention is to provide an additive manufacturing internal flow channel polishing system, which aims to solve the problems existing in the background art.

[0006] The present invention is implemented as follows: an additive manufacturing internal flow channel polishing system includes:

[0007] A cleaning tank, wherein the cleaning tank is provided with a cleaning tank outlet and a cleaning tank inlet;

[0008] A pickling tank, wherein the pickling tank is provided with a pickling tank outlet and a pickling tank inlet;

[0009] An electrolyte tank, wherein the electrolyte tank is located within a water bath;

[0010] The pump is connected to the input end of the electrolyte tank, the cleaning tank and the pickling tank through connecting pipes. The output end of the pump is connected to one end of the inner flow channel in the workpiece through connecting pipes. The other end of the inner flow channel is connected to the electrolyte tank, the cleaning tank and the pickling tank through connecting pipes.

[0011] A DC power supply, wherein the negative terminal of the DC power supply is connected to the cathode via a first wire, the cathode is immersed in an electrolyte bath, and the positive terminal of the DC power supply is connected to the workpiece.

[0012] Preferably, it further includes:

[0013] Conductive clips are uniformly clamped onto the outer shell of the workpiece, and the distribution of the conductive clips corresponds to the distribution of the inner flow channels.

[0014] The second wire connects the conductive clip to the positive terminal of the DC power supply.

[0015] Preferably, it further includes:

[0016] A pressure gauge is installed on the connecting pipe between the pump and the workpiece;

[0017] The first switch is installed on the connecting pipe between the pump and the electrolyte tank;

[0018] The fourth switch is installed on the connecting pipe between the pump and the cleaning tank;

[0019] The sixth switch is installed on the connecting pipe between the pump and the pickling tank;

[0020] The second switch is installed on the connecting pipe that connects the workpiece and the electrolyte tank.

[0021] The third switch is installed on the connecting pipe that connects the workpiece and the cleaning tank.

[0022] The fifth switch is installed on the connecting pipe between the workpiece and the pickling tank.

[0023] Preferably, the electrolyte in the electrolyte cell comprises the following raw materials by weight percentage:

[0024] Sulfuric acid 0.1-10%, citric acid 6-10%, ammonium chloride 0.1-0.5%, sodium phosphate 5-10%, sodium chloride 10-30%, p-hydroxybenzoic acid 1-3%, polyethylene glycol-4000 2-5%, sodium dodecyl sulfonate 0.1-1%, EDTA 0.1-1%, glycerol 1-3%, balance water.

[0025] Preferably, the cathode is a lead plate or graphite.

[0026] Preferably, the water bath heats the electrolyte tank, and the water bath heating temperature is 60-80°C.

[0027] Preferably, the pickling solution in the pickling tank includes sulfuric acid and water, and the pH of the pickling solution is 2 to 4.

[0028] Another objective of this invention is to provide a method for polishing internal flow channels in additive manufacturing, comprising the following steps:

[0029] Perform a cleaning of the internal flow channel;

[0030] Pickling of the inner flow channel;

[0031] The inner flow channel is cleaned a second time to remove the residual pickling solution after pickling;

[0032] The electrolyte flows within the inner channel, and the power is turned on to electrolyze the inner channel, thus polishing it.

[0033] Preferably, the pickling time is 1 to 5 minutes.

[0034] Preferably, in the step of driving the electrolyte to circulate within the inner flow channel, the pressure is 0.1–10 MPa;

[0035] In the step of electrolyzing the inner flow channel, the current density is 5–20 A / dm³. 2 The voltage is 5–20V and the electrolysis time is 20–40min.

[0036] This invention provides an additive manufacturing internal flow channel polishing system, comprising an electrolyte tank containing electrolyte and a DC power supply. The workpiece is connected to the positive terminal of the DC power supply as the anode, and the cathode is immersed in the electrolyte tank and connected to the negative terminal of the DC power supply. During polishing, the electrolyte is only passed through the internal flow channel to be polished, thus confining the electropolishing process to the area of ​​the internal flow channel to be polished. Simultaneously, the concentration of acids and salts with high conductivity in the electrolyte is increased, thereby improving the conductivity of the electrolyte. The resistance is controlled by adjusting the distance between the workpiece (anode) and the cathode to achieve the target current density. Furthermore, conductive clips are held at multiple positions on the outer shell to ensure a more uniform current density at different positions on the workpiece during electrolysis, improving the uniformity of the electrolysis. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of an additive manufacturing internal flow channel polishing system provided in an embodiment of the present invention (point A is the cathode position, and point B is the workpiece outlet position);

[0038] Figure 2 This is a schematic diagram of a workpiece clamping structure in an additive manufacturing internal flow channel polishing system provided by an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of a workpiece in an additive manufacturing internal flow channel polishing system provided in an embodiment of the present invention.

[0040] In the attached diagram: 1-Water bath; 2-Electrolyte tank; 3-Cathode; 4-First conductor; 5-Connecting pipe; 6-First switch; 7-Pump; 8-Pressure gauge; 9-Workpiece; 10-Second switch; 11-DC power supply; 12-Third switch; 13-Outlet of cleaning tank; 14-Cleaning tank; 15-Inlet of cleaning tank; 16-Fourth switch; 17-Fifth switch; 18-Outlet of pickling tank; 19-Pickling tank; 20-Inlet of pickling tank; 21-Sixth switch; 22-Inner flow channel; 23-Outer shell; 24-Conductive clip; 25-Second conductor. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0042] like Figures 1 to 2 As shown, an additive manufacturing internal flow channel polishing system according to an embodiment of the present invention includes:

[0043] The cleaning tank 14 is provided with a cleaning tank outlet 13 and a cleaning tank inlet 15, which can clean the inner flow channel 22 of the workpiece 9 and wash away impurities, dust and the like.

[0044] Pickling tank 19 is provided with pickling tank outlet 18 and pickling tank inlet 20. The pickling solution in pickling tank 19 includes sulfuric acid and water. The pH of the pickling solution is 2 to 4. It can pickle the inner flow channel 22 of workpiece 9 to remove oil stains, etc.

[0045] Electrolyte tank 2 is located within water bath 1. Water bath 1 heats electrolyte tank 2 at a temperature of 60–80°C. The electrolyte in electrolyte tank 2 comprises the following raw materials by weight percentage: sulfuric acid 0.1–10%, citric acid 6–10%, ammonium chloride 0.1–0.5%, sodium phosphate 5–10%, sodium chloride 10–30%, p-hydroxybenzoic acid 1–3%, polyethylene glycol-4000 2–5%, sodium dodecyl sulfonate 0.1–1%, EDTA 0.1–1%, glycerol 1–3%, with the balance being water.

[0046] Pump 7 is connected to the input end of the electrolyte tank 2, the cleaning tank 14 and the pickling tank 19 through connecting pipe 5. The output end of pump 7 is connected to one end of the inner flow channel 22 in the workpiece 9 through connecting pipe 5. The other end of the inner flow channel 22 is connected to the electrolyte tank 2, the cleaning tank 14 and the pickling tank 19 through connecting pipe 5. Pump 7 can drive water, pickling solution and electrolyte to flow through the inner flow channel 22 of workpiece 9 respectively, so as to perform water washing, pickling and electrolysis respectively.

[0047] A DC power supply 11 is provided, the negative terminal of which is connected to a cathode 3 via a first wire 4. The cathode 3 is immersed in an electrolyte pool 2 and is made of lead or graphite. Conductive clips 24 are uniformly clamped on the outer shell 23 of the workpiece 9. The distribution of the conductive clips 24 corresponds to the distribution of the inner flow channel 22. The conductive clips 24 are connected to the positive terminal of the DC power supply 11 via a second wire 25.

[0048] A pressure gauge 8 is installed on the connecting pipe 5 connecting the pump 7 to the workpiece 9; a first switch 6 is installed on the connecting pipe 5 connecting the pump 7 to the electrolyte tank 2; a fourth switch 16 is installed on the connecting pipe 5 connecting the pump 7 to the cleaning tank 14; a sixth switch 21 is installed on the connecting pipe 5 connecting the pump 7 to the pickling tank 19; a second switch 10 is installed on the connecting pipe 5 connecting the workpiece 9 to the electrolyte tank 2; a third switch 12 is installed on the connecting pipe 5 connecting the workpiece 9 to the cleaning tank 14; and a fifth switch 17 is installed on the connecting pipe 5 connecting the workpiece 9 to the pickling tank 19.

[0049] The pump 7 can be one of the following: slurry pump, material pump, mud pump, screw pump, sand suction pump, and diaphragm pump;

[0050] Both the pump 7 and the connecting pipe 5 are made of materials resistant to strong acid corrosion.

[0051] Another embodiment of the present invention provides a method for polishing internal flow channels in additive manufacturing, comprising the following steps:

[0052] (1) Connect the electrolyte tank 2, cleaning tank 14, pickling tank 19, pump 7, workpiece 9, etc. Pour electrolyte into electrolyte tank 2, ensuring the liquid level covers the cathode 3. Pour pickling solution into pickling tank 19 through pickling tank inlet 20. Pour clean water into cleaning tank 14 through cleaning tank inlet 15. Based on the distribution of the internal flow channels 22 in workpiece 9, evenly clamp conductive clips 24 along the pipeline direction on the outer shell 23, with an interval of 5-15mm. Multi-point clamping can make the electric field distribution on the surface of the outer shell 23 as uniform as possible, making it less likely to cause problems such as excessive local current and uneven polishing during electrolytic polishing (e.g., Figure 2 (as shown);

[0053] (2) Set the temperature of water bath 1 to heat the electrolyte in a water bath at a temperature of 60-80℃;

[0054] (3) Open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water to remove impurities, powder and other debris inside the inner flow channel 22.

[0055] (4) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn on the pump 7, pickle the inner flow channel 22 to remove the internal oil stains, and control the time to 1-5 minutes.

[0056] (5) Close the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn off the pump 7, open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water to remove residual acid.

[0057] (6) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the first switch 6 and the second switch 10 on the electrolyte tank 2, turn on the pump 7, allow the electrolyte to flow, control the pressure to be 0.1-1 MPa, turn on the DC power supply 11, and adjust the current density to 5-20 A / dm³. 2The voltage ranges from 5 to 20V, and the electrolysis time ranges from 20 to 40 minutes. When calculating the current density, the current is the actual current in the circuit, the area is the surface area of ​​the inner flow channel to be polished (i.e., inner flow channel 22), and the distance the electrolyte flows between point A and point B is L. When adjusting the current, the distance L can be adjusted. Shortening the distance L can increase the current intensity to achieve the required current density.

[0058] (7) Turn off DC power supply 11, turn off pump 7 after polishing is completed, turn off the first switch 6 and the second switch 10 of electrolyte flow channel, turn on the fourth switch 16 and the third switch 12 of clear water flow channel, turn on pump 7 to clean, collect the outlet liquid flowing out of inner flow channel 22, test pH, and end cleaning when pH is 7; otherwise, the water needs to be replaced.

[0059] (8) Remove workpiece 9 and blow or dry the inner flow channel 22 of workpiece 9.

[0060] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0061] Example 1

[0062] A method for polishing internal flow channels in additive manufacturing includes the following steps:

[0063] (1) Connect the electrolyte tank 2, cleaning tank 14, pickling tank 19, pump 7, workpiece 9 and other devices. Pour electrolyte into electrolyte tank 2, the liquid level should cover the cathode 3, the cathode 3 is a lead plate. Pour pickling solution into pickling tank 19 through pickling tank inlet 20. The pH of pickling solution is 3.2. Pour clean water into cleaning tank 14 through cleaning tank inlet 15. According to the distribution of the internal flow channel 22 in workpiece 9, evenly clamp conductive clips 24 on the outer shell 23 along the pipeline direction, with an interval of 5mm. The electrolyte includes the following raw materials by weight percentage: sulfuric acid 7%, citric acid 6%, ammonium chloride 0.3%, sodium phosphate 8%, sodium chloride 25%, p-hydroxybenzoic acid 1%, polyethylene glycol-400 3%, sodium dodecyl sulfonate 0.5%, EDTA 0.5%, glycerin 2%, and the remainder is water.

[0064] (2) Set the temperature of water bath 1 to heat the electrolyte in a water bath at 60°C;

[0065] (3) Open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0066] (4) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn on the pump 7, and pickle the inner flow channel 22 for 3 minutes.

[0067] (5) Close the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn off the pump 7, open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0068] (6) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the first switch 6 and the second switch 10 on the electrolyte tank 2, turn on the pump 7, allow the electrolyte to flow, control the pressure to 0.5 MPa, turn on the DC power supply 11, and adjust the current density to 5 A / dm³. 2 The voltage is 5V and the electrolysis time is 40min;

[0069] (7) Turn off DC power supply 11, turn off pump 7 after polishing is completed, turn off the first switch 6 and the second switch 10 of electrolyte flow channel, turn on the fourth switch 16 and the third switch 12 of clear water flow channel, turn on pump 7 to clean, collect the outlet liquid flowing out of inner flow channel 22, test pH, and end cleaning when pH is 7; otherwise, the water needs to be replaced.

[0070] (8) Remove workpiece 9 and blow dry the inner flow channel 22 of workpiece 9.

[0071] Example 2

[0072] A method for polishing internal flow channels in additive manufacturing includes the following steps:

[0073] (1) Connect the electrolyte tank 2, cleaning tank 14, pickling tank 19, pump 7, workpiece 9 and other devices. Pour electrolyte into electrolyte tank 2, the liquid level should cover the cathode 3, the cathode 3 is a lead plate. Pour pickling solution into pickling tank 19 through pickling tank inlet 20. The pH of pickling solution is 3.2. Pour clean water into cleaning tank 14 through cleaning tank inlet 15. According to the distribution of the internal flow channel 22 in workpiece 9, evenly clamp conductive clips 24 on the outer shell 23 along the pipeline direction, with an interval of 15mm. The electrolyte includes the following raw materials by weight percentage: sulfuric acid 7%, citric acid 6%, ammonium chloride 0.3%, sodium phosphate 8%, sodium chloride 25%, p-hydroxybenzoic acid 1%, polyethylene glycol-400 3%, sodium dodecyl sulfonate 0.5%, EDTA 0.5%, glycerin 2%, and the remainder is water.

[0074] (2) Set the temperature of water bath 1 to heat the electrolyte in a water bath at 80°C;

[0075] (3) Open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0076] (4) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn on the pump 7, and pickle the inner flow channel 22 for 3 minutes.

[0077] (5) Close the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn off the pump 7, open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0078] (6) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the first switch 6 and the second switch 10 on the electrolyte tank 2, turn on the pump 7, allow the electrolyte to flow, control the pressure to 0.5 MPa, turn on the DC power supply 11, and adjust the current density to 20 A / dm³. 2 The voltage is 20V and the electrolysis time is 20min;

[0079] (7) Turn off DC power supply 11, turn off pump 7 after polishing is completed, turn off the first switch 6 and the second switch 10 of electrolyte flow channel, turn on the fourth switch 16 and the third switch 12 of clear water flow channel, turn on pump 7 to clean, collect the outlet liquid flowing out of inner flow channel 22, test pH, and end cleaning when pH is 7; otherwise, the water needs to be replaced.

[0080] (8) Remove workpiece 9 and blow dry the inner flow channel 22 of workpiece 9.

[0081] Example 3

[0082] A method for polishing internal flow channels in additive manufacturing includes the following steps:

[0083] (1) Connect the electrolyte tank 2, cleaning tank 14, pickling tank 19, pump 7, workpiece 9 and other devices. Pour electrolyte into electrolyte tank 2, the liquid level should cover the cathode 3, the cathode 3 is a lead plate. Pour pickling solution into pickling tank 19 through pickling tank inlet 20. The pH of pickling solution is 3.2. Pour clean water into cleaning tank 14 through cleaning tank inlet 15. According to the distribution of the internal flow channel 22 in workpiece 9, evenly clamp conductive clips 24 on the outer shell 23 along the pipeline direction, with an interval of 10mm. The electrolyte includes the following raw materials by weight percentage: sulfuric acid 7%, citric acid 6%, ammonium chloride 0.3%, sodium phosphate 8%, sodium chloride 25%, p-hydroxybenzoic acid 1%, polyethylene glycol-400 3%, sodium dodecyl sulfonate 0.5%, EDTA 0.5%, glycerin 2%, and the remainder is water.

[0084] (2) Set the temperature of water bath 1 to heat the electrolyte in a water bath at 70°C;

[0085] (3) Open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0086] (4) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn on the pump 7, and pickle the inner flow channel 22 for 3 minutes.

[0087] (5) Close the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn off the pump 7, open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0088] (6) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the first switch 6 and the second switch 10 on the electrolyte tank 2, turn on the pump 7, allow the electrolyte to flow, control the pressure to 0.5 MPa, turn on the DC power supply 11, and adjust the current density to 12 A / dm³. 2 The voltage is 12V and the electrolysis time is 30min;

[0089] (7) Turn off DC power supply 11, turn off pump 7 after polishing is completed, turn off the first switch 6 and the second switch 10 of electrolyte flow channel, turn on the fourth switch 16 and the third switch 12 of clear water flow channel, turn on pump 7 to clean, collect the outlet liquid flowing out of inner flow channel 22, test pH, and end cleaning when pH is 7; otherwise, the water needs to be replaced.

[0090] (8) Remove workpiece 9 and blow dry the inner flow channel 22 of workpiece 9.

[0091] Example 4

[0092] A method for polishing internal flow channels in additive manufacturing includes the following steps:

[0093] (1) Connect the electrolyte tank 2, cleaning tank 14, pickling tank 19, pump 7, workpiece 9 and other devices. Pour electrolyte into electrolyte tank 2, the liquid level should cover the cathode 3, the cathode 3 is graphite. Pour pickling solution into pickling tank 19 through pickling tank inlet 20. The pH of pickling solution is 2. Pour clean water into cleaning tank 14 through cleaning tank inlet 15. According to the distribution of the internal flow channel 22 in workpiece 9, evenly clamp conductive clips 24 on the outer shell 23 along the pipeline direction, with an interval of 12mm. The electrolyte includes the following raw materials by weight percentage: sulfuric acid 7%, citric acid 6%, ammonium chloride 0.3%, sodium phosphate 8%, sodium chloride 25%, p-hydroxybenzoic acid 1%, polyethylene glycol-400 3%, sodium dodecyl sulfonate 0.5%, EDTA 0.5%, glycerin 2%, and the remainder is water.

[0094] (2) Set the temperature of water bath 1 to heat the electrolyte in a water bath at 70°C;

[0095] (3) Open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0096] (4) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn on the pump 7, and pickle the inner flow channel 22 for 5 minutes.

[0097] (5) Close the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn off the pump 7, open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0098] (6) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the first switch 6 and the second switch 10 on the electrolyte tank 2, turn on the pump 7, allow the electrolyte to flow, control the pressure to 1MPa, turn on the DC power supply 11, and adjust the current density to 15A / dm³. 2 The voltage is 6.5V and the electrolysis time is 30min;

[0099] (7) Turn off DC power supply 11, turn off pump 7 after polishing is completed, turn off the first switch 6 and the second switch 10 of electrolyte flow channel, turn on the fourth switch 16 and the third switch 12 of clear water flow channel, turn on pump 7 to clean, collect the outlet liquid flowing out of inner flow channel 22, test pH, and end cleaning when pH is 7; otherwise, the water needs to be replaced.

[0100] (8) Remove workpiece 9 and blow dry the inner flow channel 22 of workpiece 9.

[0101] Example 5

[0102] A method for polishing internal flow channels in additive manufacturing includes the following steps:

[0103] (1) Connect the electrolyte tank 2, cleaning tank 14, pickling tank 19, pump 7, workpiece 9 and other devices. Pour electrolyte into electrolyte tank 2, the liquid level should cover the cathode 3, the cathode 3 is graphite. Pour pickling solution into pickling tank 19 through pickling tank inlet 20. The pH of pickling solution is 4. Pour clean water into cleaning tank 14 through cleaning tank inlet 15. According to the distribution of the internal flow channel 22 in workpiece 9, evenly clamp conductive clips 24 on the outer shell 23 along the pipeline direction, with an interval of 7mm. The electrolyte includes the following raw materials by weight percentage: sulfuric acid 7%, citric acid 6%, ammonium chloride 0.3%, sodium phosphate 8%, sodium chloride 25%, p-hydroxybenzoic acid 1%, polyethylene glycol-400 3%, sodium dodecyl sulfonate 0.5%, EDTA 0.5%, glycerin 2%, and the remainder is water.

[0104] (2) Set the temperature of water bath 1 to heat the electrolyte in a water bath at 70°C;

[0105] (3) Open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0106] (4) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn on the pump 7, and pickle the inner flow channel 22 for 1 minute.

[0107] (5) Close the fifth switch 17 and the sixth switch 21 on the pickling tank 19, turn off the pump 7, open the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn on the pump 7, and wash the inner flow channel 22 with water.

[0108] (6) Close the fourth switch 16 and the third switch 12 on the cleaning tank 14, turn off the pump 7, open the first switch 6 and the second switch 10 on the electrolyte tank 2, turn on the pump 7, allow the electrolyte to flow, control the pressure to 0.1 MPa, turn on the DC power supply 11, and adjust the current density to 15 A / dm³. 2 The voltage is 6.5V and the electrolysis time is 30min;

[0109] (7) Turn off DC power supply 11, turn off pump 7 after polishing is completed, turn off the first switch 6 and the second switch 10 of electrolyte flow channel, turn on the fourth switch 16 and the third switch 12 of clear water flow channel, turn on pump 7 to clean, collect the outlet liquid flowing out of inner flow channel 22, test pH, and end cleaning when pH is 7; otherwise, the water needs to be replaced.

[0110] (8) Remove workpiece 9 and dry the inner flow channel 22 of workpiece 9.

[0111] Example 6

[0112] Except for the electrolyte, which includes the following raw materials by weight percentage: sulfuric acid 0.1%, citric acid 10%, ammonium chloride 0.1%, sodium phosphate 5%, sodium chloride 10%, p-hydroxybenzoic acid 2%, polyethylene glycol-400 2%, sodium dodecyl sulfonate 0.1%, EDTA 0.1%, glycerol 1%, and the remainder being water, all other contents are the same as in Example 1.

[0113] Example 7

[0114] Except for the electrolyte, which includes the following raw materials by weight percentage: sulfuric acid 10%, citric acid 8%, ammonium chloride 0.5%, sodium phosphate 10%, sodium chloride 30%, p-hydroxybenzoic acid 3%, polyethylene glycol-400 5%, sodium dodecyl sulfonate 1%, EDTA 1%, glycerol 3%, and the remainder being water, all other contents are the same as in Example 1.

[0115] Polishing effect inspection:

[0116] according to Figure 3 The structure of the workpiece sample was determined by cutting the sample (5 in total). A roughness tester was used to sample 7 points at each straight pipe and bend of each sample, and the average value of the data for each sample was taken.

[0117] The internal flow channels of the five samples were polished according to the polishing methods described in Examples 1-5. A roughness tester was then used to sample seven locations at each of the straight sections and bends of each sample. The average data for each sample was taken, and the results are shown in Table 1.

[0118] Table 1

[0119]

[0120] Following the traditional abrasive polishing method, four samples were selected, and the roughness of the samples before and after polishing was measured. The results are shown in Table 2.

[0121] Table 2

[0122]

[0123]

[0124] As can be seen from Table 1, the polishing method provided by the embodiments of the present invention can reduce the surface roughness of the inner flow channel. As can be seen from Table 2, the polishing method provided by the embodiments of the present invention has better effect compared with traditional abrasive polishing methods.

[0125] The above description is only a preferred embodiment of the present invention and is 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 within the protection scope of the present invention.

Claims

1. An additive manufacturing internal flow channel polishing system, characterized in that, include: A cleaning tank (14) is provided with a cleaning tank outlet (13) and a cleaning tank inlet (15). Pickling tank (19), wherein the pickling tank (19) is provided with pickling tank outlet (18) and pickling tank inlet (20). Electrolyte tank (2), which is located inside water bath (1); Pump (7), the electrolyte tank (2), the cleaning tank (14) and the pickling tank (19) are respectively connected to the input end of pump (7) through connecting pipe (5), the output end of pump (7) is connected to one end of the inner flow channel (22) in workpiece (9) through connecting pipe (5), and the other end of the inner flow channel (22) is connected to the electrolyte tank (2), the cleaning tank (14) and the pickling tank (19) through connecting pipe (5); A DC power supply (11) is provided, the negative terminal of which is connected to the cathode (3) via a first wire (4), the cathode (3) is immersed in an electrolyte pool (2), and the positive terminal of which is connected to the workpiece (9). Conductive clips (24) are evenly clamped on the outer shell (23) of the workpiece (9), and the distribution position of the conductive clips (24) corresponds to the distribution position of the inner flow channel (22); The second wire (25) is used to connect the conductive clip (24) to the positive terminal of the DC power supply (11). The inner flow channel (22) is an inner flow channel with a curved structure; The electrolyte in the electrolyte tank (2) comprises the following raw materials by weight percentage: Sulfuric acid 0.1-10%, citric acid 6-10%, ammonium chloride 0.1-0.5%, sodium phosphate 5-10%, sodium chloride 10-30%, p-hydroxybenzoic acid 1-3%, polyethylene glycol-4000 2-5%, sodium dodecyl sulfonate 0.1-1%, EDTA 0.1-1%, glycerol 1-3%, with the balance being water.

2. The additive manufacturing internal flow channel polishing system according to claim 1, characterized in that, Also includes: A pressure gauge (8) is installed on the connecting pipe (5) connecting the pump (7) and the workpiece (9); The first switch (6) is installed on the connecting pipe (5) that connects the pump (7) and the electrolyte tank (2); The fourth switch (16) is installed on the connecting pipe (5) connecting the pump (7) and the cleaning tank (14); The sixth switch (21) is installed on the connecting pipe (5) connecting the pump (7) and the pickling tank (19); The second switch (10) is installed on the connecting pipe (5) that connects the workpiece (9) and the electrolyte tank (2); The third switch (12) is installed on the connecting pipe (5) that connects the workpiece (9) and the cleaning tank (14); The fifth switch (17) is installed on the connecting pipe (5) that connects the workpiece (9) and the pickling tank (19).

3. The additive manufacturing internal flow channel polishing system according to claim 1, characterized in that, The cathode (3) is a lead plate or graphite.

4. The additive manufacturing internal flow channel polishing system according to claim 1, characterized in that, The water bath (1) heats the electrolyte pool (2) in a water bath, and the temperature of the water bath heating is 60~80℃.

5. The additive manufacturing internal flow channel polishing system according to claim 1, characterized in that, The pickling solution in the pickling tank (19) includes sulfuric acid and water, and the pH of the pickling solution is 2 to 4.

6. A polishing method for an additive manufacturing internal flow channel polishing system as described in any one of claims 1-5, characterized in that, Includes the following steps: Clean the inner flow channel (22) once; Pickling is performed on the inner flow channel (22); The inner flow channel (22) is cleaned a second time to remove the pickling solution remaining after pickling; The electrolyte flows in the inner channel (22), and the power is turned on to electrolyze the inner channel (22), which can polish the inner channel (22).

7. The polishing method according to claim 6, characterized in that, The pickling time is 1 to 5 minutes.

8. The polishing method according to claim 6, characterized in that, In the step of driving the electrolyte to flow in the inner flow channel (22), the pressure is 0.1~1MPa; In the step of electrolyzing the inner flow channel (22), the current density is 5~20A / dm. 2 The voltage is 5~20V and the electrolysis time is 20~40min.

Images