A method of additive manufacturing and internal surface treatment of an internal flow channel part

Abstract

The present application belongs to the technical field of additive manufacturing, and particularly relates to a method for additive manufacturing and inner surface treatment of an inner flow channel part, comprising the following steps: preparing the inner flow channel part through additive manufacturing technology according to a CAD digital model; arranging a magnetic field outside the part; sending magnetic powder wrapped with an organic binder into the inner flow channel of the part in the presence of the external magnetic field; injecting pressurized gas into the inner flow channel of the part; removing the magnetic field arranged outside the part; heating the part in a heat treatment furnace; arranging a magnetic field outside the part; sending a magnetic needle into the inner flow channel of the part and making it pass through the inner flow channel in the presence of the external magnetic field; repeating the above steps for 3-5 times, and then removing the external magnetic field; and injecting pressurized gas into the inner flow channel of the part to complete the inner surface treatment of the part. The method can significantly improve the problem of large surface roughness of the complex inner flow channel of the additive manufacturing.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of additive manufacturing, and particularly relates to a method for additive manufacturing and inner surface treatment of an inner flow channel part. BACKGROUND

[0002] The technical characteristics of additive manufacturing, i.e., layer-by-layer manufacturing, result in obvious texture features on the surface of an additive manufacturing workpiece, and the surface roughness Ra is generally above 10 microns. The ladder effect, spheroidization effect and powder adhesion unique to additive manufacturing are main factors leading to poor surface roughness of an additive manufacturing metal part. Although improving the quality of metal powder, optimizing the stacking forming direction and optimizing the process parameters can improve the surface quality of the additive manufacturing part to a certain extent, the problem of rough surface of the additive manufacturing part cannot be completely solved. The rough surface is prone to stress concentration, and then microcracks are generated, which greatly reduces the fatigue performance of the part. Therefore, the surface of the additive manufacturing metal part needs to be processed to meet the use requirements.

[0003] At present, the main surface treatment methods include cutting, manual polishing, abrasive belt / wheel polishing, sand blasting, laser polishing, chemical polishing, electrochemical polishing and abrasive flow polishing. However, the additive manufacturing complex inner flow channel is narrow in space, and when the traditional method is used for surface post-treatment of the additive manufacturing complex inner flow channel, the problem of poor accessibility is faced, and it is difficult to achieve ideal treatment effect. Therefore, it is urgent to develop a surface post-treatment method for additive manufacturing complex inner flow channel to improve the surface roughness and promote the more extensive application of additive manufacturing technology. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method for additive manufacturing and inner surface treatment of an inner flow channel part, which can significantly improve the problem of large surface roughness of the additive manufacturing complex inner flow channel.

[0005] The present application provides a method for additive manufacturing and inner surface treatment of an inner flow channel part, comprising the following steps:

[0006] Step a: establishing a CAD digital model of the inner flow channel part;

[0007] Step b: placing metal powder into a powder bin of an additive manufacturing equipment, and completing part manufacturing through additive manufacturing technology according to the CAD digital model established in step a to obtain an additive manufacturing part;

[0008] Step c: mixing an organic binder with magnetic powder having a particle size of 5 microns to 10 microns, so that the surface of the magnetic powder is wrapped with a layer of the organic binder;

[0009] Step d: arranging a magnetic field outside the additive manufacturing part;

[0010] Step e: after step d is completed, the magnetic powder treated in step c is sent into the inner flow channel of the additive manufacturing part in the presence of an external magnetic field;

[0011] Step f: after step e is completed, pressurized gas is injected into the inner flow channel of the additive manufacturing part;

[0012] Step g: after step f is completed, the magnetic field arranged outside the additive manufacturing part is removed;

[0013] Step h: after step g is completed, the additive manufacturing part is placed into a heat treatment furnace for heating;

[0014] Step i: after step h is completed, a magnetic field is arranged outside the additive manufacturing part;

[0015] Step j: after step i is completed, a magnetic needle is sent into the inner flow channel of the additive manufacturing part and passed through the inner flow channel in the presence of an external magnetic field;

[0016] Step k: after step j is repeated for 3-5 times, the external magnetic field is removed;

[0017] Step l: after step k is completed, pressurized gas is injected into the inner flow channel of the additive manufacturing part, and the inner surface treatment of the part is completed.

[0018] In the method provided by the present application, in step b, the material of the additive manufacturing part includes but is not limited to GH3625 high-temperature alloy, TC4 titanium alloy or GH5188 high-temperature alloy.

[0019] In the method provided by the present application, in step b, the diameter of the inner flow channel of the additive manufacturing part is preferably 5-25 mm, and specifically can be 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm or 25 mm.

[0020] In the method provided by the present application, in step c, the purpose of using the magnetic powder is to form a dense metal with good bonding strength in the concave area of the original uneven surface of the inner flow channel. If the particle size of the magnetic powder is greater than 10 μm, it is difficult to fully fill the concave area, and the improvement effect on the surface roughness of the inner flow channel is not good. At the same time, the powder with a particle size greater than 10 μm has a poor sintering effect in the subsequent heating process of step h, and the density after sintering is poor, the bonding strength is poor, and it is easy to peel off and fall off. The magnetic powder with a particle size less than 5 μm has poor flowability and is difficult to be sprayed out using a spray gun. Therefore, the particle size of the magnetic powder used is between 5 μm and 10 μm, and can be specifically 5 μm, 5.5 μm, 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm, 9 μm, 9.5 μm or 10 μm.

[0021] In the method provided by the present application, in step c, the magnetic powder is preferably 410 stainless steel magnetic powder and / or 430 stainless steel magnetic powder; the organic binder includes but is not limited to polyvinyl alcohol; and the mass ratio of the magnetic powder to the organic binder is preferably 100: (0.05-0.5), and can be specifically 100:0.05, 100:0.1, 100:0.15, 100:0.2, 100:0.25, 100:0.3, 100:0.35, 100:0.4, 100:0.45 or 100:0.5.

[0022] In the method provided by the present application, in step c, two spray guns are preferably used when the magnetic powder is mixed with the organic binder, one spray gun is loaded with the magnetic powder, and the other spray gun is loaded with the organic binder. The organic binder is sprayed onto the sprayed magnetic powder using the other spray gun at the same time. This has the beneficial effect that the organic binder can be uniformly wrapped on the surface of the magnetic powder, and can promote the formation of a dense metal with good bonding strength in the subsequent heating process of step h. Moreover, this method is simple to operate, the equipment is low in price, and is conducive to the popularization and application of the method of the present application.

[0023] In the method provided by the present application, there is no sequence requirement between step c and steps a and b.

[0024] In the method provided by the present application, in step d, the magnetic field preferably conforms to the shape of the inner flow channel of the additive manufacturing part and covers the internal area of the inner flow channel. This can ensure that the magnetic powder is uniformly distributed in the inner flow channel in the subsequent step e under the action of the magnetic field.

[0025] In the method provided by the present application, in step e, the external magnetic field can make the sent magnetic powder uniformly cover the surface of the inner flow channel, and these magnetic powders can form a metal uniformly covering the surface of the inner flow channel in the subsequent heating process of step h.

[0026] In the method provided by the present application, in step f, the pressurized gas is injected into the inner flow channel, so as to make the magnetic powder gather in the concave area of the original uneven surface of the inner flow channel by mechanical extrusion of the gas. Meanwhile, the magnetic powder wrapped with the binder can be fully adhered to each other and to the surface of the inner flow channel under the action of the gas pressure. In this way, it can be ensured that the magnetic powder forms a dense metal with good bonding strength in the concave area of the original uneven surface of the inner flow channel after the heating treatment in the subsequent step h.

[0027] In the method provided by the present application, in step f, the pressure of the pressurized gas is preferably 10-20 MPa, and can be specifically 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa or 20 MPa.

[0028] In the method provided by the present application, in step f, the injection flow rate of the pressurized gas is preferably 13-23 L / min, and can be specifically 13 L / min, 14 L / min, 15 L / min, 16 L / min, 17 L / min, 18 L / min, 19 L / min, 20 L / min, 21 L / min, 22 L / min or 23 L / min. When the gas flow rate is less than 13 L / min, the gas pressure is small, and it is difficult to achieve the full adhesion of the magnetic powder. When the gas flow rate is greater than 23 L / min, the gas flow rate is too large, which can blow the magnetic powder out of the inner flow channel and destroy the uniformity of the magnetic powder covering the surface of the inner flow channel.

[0029] In the method provided by the present application, in step f, the pressurized gas is preferably air and / or argon, which is cheap and easy to obtain, and is conducive to the popularization and application of the method of the present application.

[0030] In the method provided by the present application, in step g, the magnetic field is preferably removed from the direction parallel to the radial direction of the inner flow channel of the additive manufacturing part. This magnetic field removal method can avoid the movement of the magnetic powder that has covered the surface of the inner flow channel due to the change of the magnetic field during the magnetic field removal process, thereby destroying the uniformity of the powder distribution and ensuring that the magnetic powder can form a metal uniformly covering the surface of the inner flow channel in the heating process in the subsequent step h.

[0031] In the method provided by the present application, in step h, the heating treatment can make the magnetic powder in the concave area of the original uneven surface of the inner flow channel form a dense metal with good bonding strength through sintering, so as to realize the improvement of the surface roughness in the form of filling the concave area.

[0032] In the method provided by the application, in step h, the specific process of heating preferably comprises: first heating from ambient temperature to 50-80°C, holding for 30-60 min; continuing to heat to 200-250°C, holding for 50-70 min; heating to 800-900°C again, holding for 120-180 min; and finally cooling to ambient temperature with the furnace.

[0033] In the method provided by the application, the specific heating process in step h is described as follows:

[0034] First, heated from ambient temperature to 50-80℃, and kept for 30-60min. The purpose of this step is to make the binder fully volatilize, and avoid forming pores in the sintered metal. If the heating temperature is less than 50℃, the binder volatilizes slowly at low temperature, and the volatilization is not sufficient. If the heating temperature is greater than 80℃, the binder volatilizes too fast, and pores are easily formed, which will destroy the density of the sintered metal. Therefore, the heating temperature is preferably between 50-80℃, and can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃ or 80℃. If the holding time is less than 30min, the binder volatilizes insufficiently. If the holding time is greater than 60min, the volatilization effect of the binder cannot be significantly improved, and the processing time is prolonged, which reduces the production efficiency. Therefore, the holding time is preferably between 30-60min, and can be 30min, 35min, 40min, 45min, 50min, 55min or 60min. After the first heating treatment, continue to heat to 200-250℃, and keep for 50-70min. The purpose of this step is to pre-sinter the magnetic powder, reduce the thermal stress in the sintering process of the powder, and avoid cracking and peeling of the sintered metal. If the heating temperature is less than 200℃, the temperature is too low, and the growth kinetics of the magnetic powder is insufficient, and the sintering effect is not obvious. If the heating temperature is greater than 250℃, the temperature is too high, and the powder grows too fast, the thermal stress in the sintering process is large, and the sintered metal is prone to cracking and peeling. Therefore, the heating temperature is preferably between 200-250℃, and can be 200℃, 205℃, 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, 240℃, 245℃ or 250℃. If the holding time is less than 50min, the pre-sintering effect of the magnetic powder is not obvious. If the holding time is greater than 70min, the pre-sintering effect of the magnetic powder cannot be significantly improved, and the processing time is prolonged, which reduces the production efficiency. Therefore, the holding time is preferably between 50-70min, and can be 50min, 55min, 60min, 65min or 70min. After the second heating treatment, heat to 800-900℃, and keep for 120-180min. The purpose of this step is to form a dense metal by sintering the magnetic powder. If the heating temperature is less than 800℃, the temperature is too low, and the growth kinetics of the magnetic powder is insufficient, and the sintering effect is not obvious. If the heating temperature is greater than 900℃, the temperature is too high, and the grains of the sintered metal will grow rapidly, which will cause performance deterioration. Therefore, the heating temperature is preferably between 800-900℃, and can be 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃ or 900℃. If the holding time is less than 120min, the sintering effect of the magnetic powder is not obvious.When the holding time is greater than 180 minutes, the sintering effect of the magnetic powder cannot be significantly increased, instead, the processing time is prolonged, and the production efficiency is reduced. Therefore, the holding time is preferably between 120 minutes and 180 minutes, and specifically can be 120 minutes, 130 minutes, 140 minutes, 150 minutes, 160 minutes, 170 minutes or 180 minutes. After heating is completed, the furnace is cooled to ambient temperature, so as to achieve the effect of slow cooling, the thermal stress is slowly released, and cracking and peeling of the sintered metal is avoided.

[0035] In the method provided by the application, in step i, the magnetic field is consistent with the shape of the inner flow channel of the additive manufacturing part and covers the inner region of the inner flow channel. In this way, the magnetic needle can be uniformly passed through the inner flow channel under the action of the magnetic field in the subsequent step j.

[0036] In the method provided by the application, in step j, the magnetic needle is attracted into and through the inner flow channel, so as to further reduce the small height difference of the convex region of the original uneven surface of the sintered metal and the inner flow channel surface through the mechanical scraping action of the magnetic needle and the surface of the inner flow channel, thereby improving the surface roughness of the inner flow channel.

[0037] In the method provided by the application, in step j, the magnetic needle is preferably an iron oxide magnetic needle.

[0038] In the method provided by the application, in step j, if the diameter of the magnetic needle is less than 0.5 mm, the processing difficulty of the magnetic needle is too great, which is not conducive to the use of the application. If the diameter of the magnetic needle is greater than 1.5 mm, it is difficult to enter the inner flow channel with a small size, and the processing effect is limited. Therefore, the diameter of the magnetic needle is preferably between 0.5 mm and 1.5 mm, and specifically can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm or 1.5 mm. If the length of the magnetic needle is less than 3 mm, the processing difficulty of the magnetic needle is too great, which is not conducive to the use of the application. If the length of the magnetic needle is greater than 10 mm, it is difficult to enter the inner flow channel with a small size, and the processing effect is limited. Therefore, the length of the magnetic needle is preferably between 3 mm and 10 mm, and specifically can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0039] In the method provided by the application, in step k, step j is repeated 3 to 5 times, so as to sufficiently play the mechanical scraping effect of the magnetic needle. If the number of repetitions is less than 3 times, the best removal effect cannot be achieved. If the number of repetitions is greater than 5 times, the processing effect cannot be significantly increased, instead, the time is prolonged, and the production efficiency is reduced.

[0040] In the method provided by the application, in step k, the magnetic field is preferably removed from a direction parallel to the axis of the internal flow channel in the additive manufacturing part. This way of removing the magnetic field can fully remove the magnetic needle and avoid residual magnetic needles.

[0041] In the method provided by the application, in step l, the pressurized gas is injected into the internal flow channel to further clean the internal flow channel of possible residual debris, magnetic needles and other excess materials.

[0042] In the method provided by the application, in step l, the pressure of the pressurized gas is preferably 10-20 MPa, and can be 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa or 20 MPa.

[0043] In the method provided by the application, in step l, when the gas flow is less than 6 L / min, the gas flow is insufficient and the cleaning effect is poor. When the gas flow is greater than 16 L / min, the amount of gas used increases, but the cleaning effect does not increase significantly, and instead the cost of using gas increases. Therefore, the injection flow of the pressurized gas is preferably between 6 L / min and 16 L / min, and can be 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 11 L / min, 12 L / min, 13 L / min, 14 L / min, 15 L / min or 16 L / min.

[0044] In the method provided by the application, in step l, the pressurized gas is preferably air and / or argon, which is inexpensive and easy to obtain, and is conducive to the popularization and application of the method of the application.

[0045] Compared with the prior art, the application has the beneficial effect that when the complex internal flow channel surface of the additive manufacturing part is treated under the synergistic action of a magnetic field, a high-pressure gas flow and a thermal field, the accessibility is better, and the internal surface roughness can be effectively improved. DETAILED DESCRIPTION

[0046] The technical solutions of the application will be described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the application, rather than all the embodiments, and are only used to illustrate the application, and should not be regarded as limiting the scope of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0047] Example 1

[0048] The embodiment provides a method for additive manufacturing and inner surface treatment of a GH3625 high-temperature alloy fuel spray rod, and comprises the following steps:

[0049] 1) A CAD digital model of the GH3625 high-temperature alloy fuel spray rod is established, wherein the fuel spray rod has a complex inner flow channel, and the diameter of the inner flow channel is 6 mm.

[0050] 2) GH3625 high-temperature alloy powder is placed in a powder bin of a laser selective melting additive manufacturing device, and laser selective melting additive manufacturing of the fuel spray rod is completed according to the established CAD digital model.

[0051] 3) 410 stainless steel magnetic powder (particle size is 7 μm) is loaded into one spray gun, and polyvinyl alcohol organic binder is loaded into another spray gun, the magnetic powder is sprayed from the spray gun at the same time, the organic binder is sprayed to the sprayed magnetic powder by using the other spray gun, the surface of the magnetic powder is wrapped with a layer of organic binder, and the amount of the organic binder is 0.2% of the mass of the magnetic powder.

[0052] 4) A magnetic field is arranged outside the fuel spray rod, the magnetic field covers the inner flow channel region of the fuel spray rod and is consistent with the shape of the inner flow channel.

[0053] 5) The 410 stainless steel powder wrapped with the binder is poured from one end of the inner flow channel of the fuel spray rod, the powder is attracted into the inner flow channel by the external magnetic field, and the powder is covered on the surface of the inner flow channel under the action of the magnetic field.

[0054] 6) High-pressure argon gas with a gas pressure of 15 MPa and a gas flow of 13 L / min is introduced from one end of the inner flow channel of the fuel spray rod.

[0055] 7) The external magnetic field is removed from the direction parallel to the radial direction of the inner flow channel of the fuel spray rod.

[0056] 8) The fuel spray rod is placed in a heat treatment furnace for heating, first heated from room temperature to 50 DEG C, and kept for 60 min; then heated to 250 DEG C, and kept for 50 min; then heated to 900 DEG C, and kept for 120 min; finally, the furnace is cooled to room temperature.

[0057] 9) A magnetic field is arranged outside the fuel spray rod, the magnetic field covers the inner flow channel region of the fuel spray rod and is consistent with the shape of the inner flow channel.

[0058] 10) Iron oxide magnetic needles with a diameter of 0.5 mm and a length of 10 mm are poured from one end of the inner flow channel of the fuel spray rod, and the magnetic needles are removed from the other end of the inner flow channel under the action of the external magnetic field.

[0059] 11) The external magnetic field is removed from the direction parallel to the radial direction of the inner flow channel of the fuel spray rod after the above step is repeated for 5 times.

[0060] 12) high pressure argon gas with a pressure of 15 MPa is introduced into the fuel spray bar inner channel from one end, and the gas flow is 6 L / min; after no residues, debris and other impurities are blown out, the aeration is stopped, and the inner surface treatment of the additive manufacturing fuel spray bar is completed.

[0061] The surface roughness of the inner channel of the additive manufacturing fuel spray bar obtained in this embodiment is measured using a roughness tester, and the surface roughness is Ra 3.2 μm, which is significantly improved compared with before the treatment using the method of the present application (surface roughness Ra 10.5 μm).

[0062] Example 2

[0063] This embodiment gives a method for additive manufacturing and inner surface treatment of a TC4 titanium alloy control shell, which comprises the following steps:

[0064] 1) A CAD digital model of a TC4 titanium alloy control shell is established, and the control shell has a complex inner channel with a diameter of 10 mm.

[0065] 2) The TC4 titanium alloy powder is placed in the powder bin of the laser selective melting additive manufacturing equipment, and the laser selective melting additive manufacturing of the control shell is completed according to the established CAD digital model.

[0066] 3) 430 stainless steel magnetic powder (particle size 10 μm) is loaded into one spray gun, and polyvinyl alcohol organic binder is loaded into another spray gun, while the magnetic powder is sprayed from the spray gun, the other spray gun sprays the organic binder to the sprayed magnetic powder, so that the surface of the magnetic powder is wrapped with a layer of organic binder, and the amount of organic binder is 0.2% of the mass of the magnetic powder.

[0067] 4) A magnetic field is arranged outside the control shell, which covers the inner channel area of the control shell and is consistent with the shape of the inner channel.

[0068] 5) The 430 stainless steel powder wrapped with the binder is poured from one end of the inner channel of the control shell, the powder is attracted into the inner channel by the external magnetic field, and the powder is covered on the surface of the inner channel under the action of the magnetic field.

[0069] 6) High pressure argon gas with a pressure of 15 MPa is introduced into the inner channel of the control shell from one end, and the gas flow is 23 L / min.

[0070] 7) The external magnetic field is removed from the direction parallel to the radial direction of the inner channel of the control shell.

[0071] 8) The control shell is placed in a heat treatment furnace for heating, first heated from room temperature to 80℃, and kept for 30 min; then heated to 200℃, and kept for 70 min; then heated to 800℃, and kept for 180 min; finally, the furnace is cooled to room temperature.

[0072] 9) A magnetic field is arranged outside the control housing, covering the inner flow passage region of the control housing and conforming to the shape of the inner flow passage.

[0073] 10) Iron oxide magnetic needles with a diameter of 1.5 mm and a length of 3 mm are poured from one end of the inner flow passage of the control housing, and under the action of the external magnetic field, the needles pass through the inner flow passage of the control housing and exit from the other end.

[0074] 11) After repeating the above step 3 times, the external magnetic field is removed from the direction parallel to the inner flow passage of the control housing.

[0075] 12) High-pressure argon gas with a pressure of 15 MPa is introduced from one end of the inner flow passage of the control housing, and the gas flow is 16 L / min; after no impurities such as residues and debris are blown out, the gas supply is stopped, and the surface post-processing of the inner flow passage of the control housing is completed.

[0076] The surface roughness of the inner flow passage of the control housing obtained in this embodiment is measured using a roughness tester, and the surface roughness is Ra 3.6 μm, which is significantly improved compared to before using the method of the present application (surface roughness Ra 11.7 μm).

[0077] Example 3

[0078] This embodiment gives a method for additive manufacturing and inner surface treatment of a GH5188 high-temperature alloy flame stabilizer, including the following steps:

[0079] 1) A CAD digital model of a GH5188 high-temperature alloy flame stabilizer is established, and the flame stabilizer has a complex inner flow passage with a diameter of 20 mm.

[0080] 2) The GH5188 high-temperature alloy powder is placed in the powder bin of the laser selective melting additive manufacturing equipment, and according to the established CAD digital model, the laser selective melting additive manufacturing of the flame stabilizer is completed.

[0081] 3) A 410 stainless steel magnetic powder (particle size 5 μm) is loaded into one spray gun, and a polyvinyl alcohol organic binder is loaded into another spray gun, while the magnetic powder is sprayed from the spray gun, the other spray gun is used to spray the organic binder to the sprayed magnetic powder, so that the surface of the magnetic powder is wrapped with a layer of organic binder, and the amount of organic binder is 0.2% of the mass of the magnetic powder.

[0082] 4) A magnetic field is arranged outside the flame stabilizer, covering the inner flow passage region of the flame stabilizer and conforming to the shape of the inner flow passage.

[0083] 5) The 410 stainless steel powder with the binder wrapped on the surface is poured from one end of the inner flow passage of the flame stabilizer, the powder is attracted into the inner flow passage by the external magnetic field, and the powder is covered on the surface of the inner flow passage under the action of the magnetic field.

[0084] 6)From one end of the inner flow channel of the flame stabilizer, high-pressure argon gas with a pressure of 15 MPa is introduced, and the gas flow rate is 16 L / min.

[0085] 7)Remove the external magnetic field from the direction parallel to the radial direction of the inner flow channel of the flame stabilizer.

[0086] 8)Put the flame stabilizer into a heat treatment furnace for heating, first heat from room temperature to 70℃, and keep for 50 min; continue to heat to 230℃, and keep for 65 min; then heat to 860℃, and keep for 150 min; finally, cool down to room temperature with the furnace.

[0087] 9)Arrange the magnetic field outside the flame stabilizer, which covers the inner flow channel area of the flame stabilizer and is consistent with the shape of the inner flow channel.

[0088] 10)Pour the iron oxide magnetic needle with a diameter of 1 mm and a length of 6 mm from one end of the inner flow channel of the flame stabilizer, and under the action of the external magnetic field, it passes through the inner flow channel of the flame stabilizer and exits from the other end.

[0089] 11)Repeat the previous step 4 times, and remove the external magnetic field from the direction parallel to the inner flow channel of the flame stabilizer.

[0090] 12)From one end of the inner flow channel of the flame stabilizer, high-pressure argon gas with a pressure of 15 MPa is introduced, and the gas flow rate is 11 L / min; after no impurities such as residues and debris are blown out, stop the gas, and complete the inner surface treatment of the additive manufacturing flame stabilizer.

[0091] Use a roughness tester to measure the surface roughness of the inner flow channel of the additive manufacturing flame stabilizer obtained in this embodiment, and the surface roughness is Ra3.4 μm, which is significantly improved compared with before using the method of the present application (surface roughness Ra10.3 μm).

[0092] The above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of additive manufacturing and internal surface treatment of an internal flow channel part, characterized by, The method comprises the following steps: Step a: establishing a CAD digital model of the internal flow channel part; Step b: placing metal powder into the powder bin of the additive manufacturing equipment, and manufacturing the part by additive manufacturing technology according to the CAD digital model established in step a to obtain an additive manufacturing part; Step c: mixing the organic binder with the magnetic powder having a particle size of 5-10 μm to coat the surface of the magnetic powder with a layer of the organic binder; Step d: arranging a magnetic field outside the additive manufacturing part; Step e: after step d is completed, sending the magnetic powder treated in step c into the internal flow channel of the additive manufacturing part in the presence of the external magnetic field; Step f: after step e is completed, injecting pressurized gas into the internal flow channel of the additive manufacturing part; Step g: after step f is completed, removing the magnetic field arranged outside the additive manufacturing part; Step h: after step g is completed, heating the additive manufacturing part in a heat treatment furnace; Step i: after step h is completed, arranging a magnetic field outside the additive manufacturing part; Step j: after step i is completed, sending a magnetic needle into the internal flow channel of the additive manufacturing part and making it pass through the internal flow channel in the presence of the external magnetic field; Step k: repeating step j for 3-5 times and then removing the external magnetic field; Step l: after step k is completed, injecting pressurized gas into the internal flow channel of the additive manufacturing part to complete the internal surface treatment of the part.

2. The method of claim 1, wherein, In step c, two spray guns are used when the magnetic powder is mixed with the organic binder, one of which is loaded with the magnetic powder and the other of which is loaded with the organic binder, and the magnetic powder is sprayed from the spray gun while the organic binder is sprayed onto the magnetic powder by using the other spray gun.

3. The method of claim 1, wherein, In step d, the magnetic field is consistent with the shape of the internal flow channel of the additive manufacturing part and covers the internal region of the internal flow channel.

4. The method of claim 1, wherein, In step f, the pressurized gas is air and / or argon, and the injection flow rate of the pressurized gas is 13-23 L / min.

5. The method of claim 1, wherein, In step g, the magnetic field is removed from the direction parallel to the radial direction of the internal flow channel of the additive manufacturing part.

6. The method of claim 1, wherein, In step h, the heating process specifically comprises: first heating from the ambient temperature to 50-80 °C and keeping the temperature for 30-60 min; continuing to heat to 200-250 °C and keeping the temperature for 50-70 min; then heating to 800-900 °C and keeping the temperature for 120-180 min; and finally cooling to the ambient temperature in the furnace.

7. The method of claim 1, wherein, In step i, the magnetic field is consistent with the shape of the internal flow channel of the additive manufacturing part and covers the internal region of the internal flow channel.

8. The method of claim 1, wherein, In step j, the diameter of the magnetic needle is 0.5-1.5 mm and the length is 3-10 mm.

9. The method of claim 1, wherein, In step k, the magnetic field is removed from the direction parallel to the axial direction of the internal flow channel of the additive manufacturing part.

10. The method of claim 1, wherein, In step l, the pressurized gas is air and / or argon, and the injection flow rate of the pressurized gas is 6-16 L / min.