A 3D printing method for injection molding panels

Abstract

The present invention belongs to the technical field of hypersonic high-temperature wind tunnel testing, and discloses a 3D printing processing method for injection panels. The 3D printing processing method for injection panels of the present invention includes designing injection panels; determining 3D printing materials; performing 3D printing; removing powder; performing heat treatment; performing mechanical processing; trial assembly of blind nozzles; performing airtightness tests; and completing assembly. The 3D printing processing method for injection panels of the present invention can integrate hundreds of parts into an integral component, and the overall mechanical properties are significantly improved; the use of 3D printing technology can omit the vacuum brazing process, and solve the risk of weld failure caused by alternating force and heat in high-temperature application environments; in addition, the processing cycle of 3D printed parts is short, which can better meet the rapid manufacturing needs of injection panels and has engineering practical value.

Description

Technical Field

[0001] The present invention belongs to the technical field of hypersonic high-temperature wind tunnel testing, and in particular relates to a 3D printing processing method for injection molding panels. Background Art

[0002] When conducting hypersonic flight and scramjet engine tests in wind tunnels, it is necessary to simulate parameters such as Mach number, pressure, temperature, and oxygen content. Air heaters are usually used to heat the test gas. Combustion heaters are widely used due to their low cost, rapid startup, long operating time, and ability to provide high enthalpy, high-pressure flow conditions. The working principle of combustion heaters is basically the same as that of liquid rocket engines. Both inject fuel and oxidizer into the combustion chamber through injectors to complete the mixing and combustion processes to produce high-temperature and high-pressure combustion gas.

[0003] The injector is the core component of the combustion heater. Its main function is to reasonably distribute the fuel and oxidant and realize the atomization and mixing of the fuel and oxidant. The number of nozzles arranged on the injection panel of the injector is generally a few to several hundred, and it is usually assembled by vacuum brazing process. The vacuum brazing process has problems such as long processing cycle, high manufacturing cost, and local failure of the weld under high temperature and alternating force and heat.

[0004] 3D printing has the advantages of one-piece molding, short processing cycle and good overall performance. Currently, there is an urgent need to develop a 3D printing processing method for injection molding panels. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a 3D printing processing method for injection molding panels to overcome the defects of the prior art.

[0006] The 3D printing processing method for the injection panel of the present invention comprises the following steps:

[0007] S10. Design injection panel;

[0008] The injection panel includes a disc-shaped gas side panel located at the top and a disc-shaped normal temperature side panel located at the bottom. A plurality of outer nozzle connection cylinders symmetrically distributed in the center are arranged between the gas side panel and the normal temperature side panel, and inner nozzles are installed in the outer nozzle connection cylinders; a plurality of supporting rib square columns uniformly distributed along the circumferential direction are arranged on the sides of the gas side panel and the normal temperature side panel, and cylindrical partitions protruding from the surface of the gas side panel are arranged on six radii uniformly distributed along the circumferential direction above the gas side panel; an upwardly protruding flange is arranged on the circumference of the gas side panel for fixedly connecting the injection panel with the combustion heater;

[0009] A circular through hole is arranged on the central axis of each outer nozzle connection cylinder for circulating the oxidant; a plurality of injection holes I are evenly distributed around the outer nozzle connection cylinder and are arranged on the circumference of each outer nozzle connection cylinder for injecting the oxidant; a plurality of injection holes II arranged in a ring shape are designed on the surface of each cylindrical partition for injecting the oxidant and providing thermal protection for the cylindrical partition in the gas environment; a plurality of injection holes III are evenly distributed along the circumference on the edge of the gas side panel for injecting the oxidant and providing thermal protection for the inner wall of the flange;

[0010] S20. Determine 3D printing materials;

[0011] Determine the 3D printing material of the injection panel according to the ambient temperature of the gas side panel. If the ambient temperature is higher than 1000℃, use high-temperature alloy materials; if the ambient temperature is lower than 1000℃, use stainless steel materials including S304;

[0012] S30. Perform 3D printing;

[0013] The use of 3D printing laser additive manufacturing technology for jetting panel printing requires that the printing equipment has the ability to print high-temperature alloy materials or stainless steel materials, the printing format covers the maximum outer dimensions of the jetting panel, and the printing height exceeds the sum of the jetting panel height and the substrate height;

[0014] Before 3D printing, the substrate is preheated several times, and the substrate preheating temperature rises in steps each time;

[0015] The thickness of 3D printing layers ranges from 0.03mm to 0.15mm;

[0016] 3D printing methods include multi-laser simultaneous printing and multi-laser upwind field printing;

[0017] The 3D printing sequence is to complete the multi-laser printing of the downwind format of the parts, and then proceed to the multi-laser printing of the upwind format;

[0018] S40. Remove powder;

[0019] After 3D printing is completed, wait for the substrate and the injection panel to cool to a safe temperature, remove the printed part of the substrate and the injection panel combination from the printing device, and then fix the printed part on the powder cleaning platform;

[0020] When the powder cleaning platform is working, the working conditions are argon atmosphere, room temperature, and pressure not higher than 2MPa. The residual powder of the printed part is removed by rotation and vibration.

[0021] After the printed part is cleaned of powder, use a plug gauge that matches the circular through hole, injection hole I, injection hole II, and injection hole III to check the circular through hole, injection hole I, injection hole II, and injection hole III one by one to ensure that there is no residual powder;

[0022] S50. Perform heat treatment;

[0023] Improve the density of printed parts and eliminate thermal stress through heat treatment;

[0024] The heat treatment process is as follows: vacuumize, heat up to A℃ at a given rate a℃ / min, and keep warm for a predetermined time; then heat up to B℃ at a given rate b℃ / min, and keep warm for a predetermined time; then fill with protective gas for partial pressure treatment; then gradually cool down and cool the printed part to room temperature; finally, vacuumize and keep for a predetermined time before taking it out of the oven;

[0025] Among them, a℃ / min, A℃, b℃ / min and B℃ are all pre-set values ​​according to the process requirements;

[0026] S60. Perform mechanical processing;

[0027] Machining of printed parts according to the requirements of injection panel assembly, sealing and installation;

[0028] The machining process is as follows: separate the injection panel and the substrate by wire cutting; remove the injection panel support structure; remove the 3D printing structure design margin of the injection panel; remove the 3D printing deformation margin of the injection panel; process the sealing structure of the injection panel; process the positioning structure of the injection panel; process the connection slot of the injection panel; process the installation slot of the inner nozzle in the cylinder for connecting the outer nozzle;

[0029] Machining equipment includes five-axis CNC lathes, milling machines and horizontal lathes;

[0030] The operating temperature of machining is room temperature and the operating pressure is atmospheric pressure;

[0031] S70. Try to assemble the blind nozzle;

[0032] Try to assemble the blind nozzle in the installation slot of each external nozzle connecting cylinder. If there are problems such as thread mismatch, improper installation, and too small gap during the trial assembly, it is necessary to perform secondary repair on the installation slot of the external nozzle connecting cylinder;

[0033] The equipment used for secondary repair includes wrenches, taps and files; the operating temperature of secondary repair is room temperature and the operating pressure is atmospheric pressure;

[0034] S80. Conduct airtightness test;

[0035] In order to test the overall sealing performance of the injection panel, an injection panel airtightness test is carried out; the tooling structure of the airtightness test includes an airtight tooling upper cover plate and an airtight tooling lower cover plate, an air inlet nozzle is installed on the airtight tooling lower cover plate, and the air inlet nozzle is externally connected to a nitrogen bottle;

[0036] The airtight test process is as follows: blind nozzles are installed in the mounting slots of the inner nozzles in the outer nozzle connecting cylinders of the injection panel respectively; a sealing ring A is placed in a sealing structure of the injection panel; the injection panel is fixed on the upper cover plate of the airtight tooling by connecting screws A; a sealing ring B is placed in another sealing structure of the injection panel; the upper cover plate of the airtight tooling and the lower cover plate of the airtight tooling are connected by connecting screws B to obtain an assembly; the assembly is placed on the operating table with the upper cover plate of the airtight tooling facing upward and the lower cover plate of the airtight tooling facing downward; water is added to the groove above the normal temperature side panel of the assembly, and the water level is higher than the sealing ring A, and the high-pressure nitrogen in the nitrogen bottle is passed into the air inlet nozzle to observe whether bubbles appear on the water surface within a predetermined time. If no bubbles appear within the predetermined time, the injection panel processing is qualified, and the 3D printing processing of the injection panel is completed;

[0037] The pressure range of high-pressure nitrogen is 1MPa~3MPa;

[0038] S90. Complete assembly;

[0039] Disassemble the assembly, remove the blind nozzle, install the inner nozzles in the mounting slots of the outer nozzle connecting cylinders of the injection panel, and obtain the injection panel assembly; install the injection panel assembly on the combustion heater through the flange, and repair it until it meets the use requirements.

[0040] The 3D printing processing method for injection molding panels of the present invention can integrate hundreds of parts into an integral component, and the overall mechanical properties are significantly improved; the use of 3D printing technology can omit the vacuum brazing process and solve the risk of weld failure caused by alternating force and heat in high-temperature application environments; in addition, the processing cycle of 3D printed parts is short, which can better meet the rapid manufacturing needs of injection molding panels and has practical engineering value. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a flow chart of the 3D printing processing method for injection molding panels of the present invention;

[0042] Figure 2 It is a structural schematic diagram of the injection panel;

[0043] Figure 3 It is a schematic diagram of the tooling structure used for the air tightness test of the injection panel of the present invention.

[0044] In the figure, 1. gas side panel; 2. normal temperature side panel; 3. external nozzle connecting cylinder; 4. supporting rib square column; 5. cylindrical partition; 6. airtight tooling upper cover plate; 7. airtight tooling lower cover plate; 8. blind nozzle; 9. air inlet nozzle; 10. water; 11. connecting screw A; 12. sealing ring B; 13. sealing ring A; 14. connecting screw B. DETAILED DESCRIPTION

[0045] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0046] Example: Figure 1 As shown, the 3D printing processing method for the injection panel of this embodiment includes the following steps:

[0047] S10. Design injection panel;

[0048] like Figure 2 As shown, the injection panel includes a disc-shaped gas side panel 1 located at the top and a disc-shaped normal temperature side panel 2 located at the bottom, and a plurality of outer nozzle connecting cylinders 3 symmetrically distributed in the center are arranged between the gas side panel 1 and the normal temperature side panel 2, and the inner nozzle is installed in the outer nozzle connecting cylinder 3; a plurality of supporting rib square columns 4 uniformly distributed along the circumferential direction are arranged on the side surfaces of the gas side panel 1 and the normal temperature side panel 2, and cylindrical partitions 5 protruding from the surface of the gas side panel 1 are arranged on six radii uniformly distributed along the circumferential direction above the gas side panel 1; an upwardly protruding flange is arranged on the circumference of the gas side panel 1 for fixedly connecting the injection panel with the combustion heater;

[0049] A circular through hole is arranged on the central axis of each outer nozzle connection cylinder 3 for circulating the oxidant; a plurality of injection holes I are evenly distributed around the outer nozzle connection cylinder 3 and are arranged on the circumference of each outer nozzle connection cylinder 3 for injecting the oxidant; a plurality of injection holes II arranged in a ring shape are designed on the surface of each cylindrical partition 5 for injecting the oxidant and providing thermal protection for the cylindrical partition 5 in the gas environment; a plurality of injection holes III evenly distributed along the circumference are arranged on the edge of the gas side panel 1 for injecting the oxidant and providing thermal protection for the inner wall surface of the flange;

[0050] S20. Determine 3D printing materials;

[0051] The 3D printing material of the injection panel is determined according to the ambient temperature of the gas side panel 1. If the ambient temperature is higher than 1000°C, a high-temperature alloy material is selected; if the ambient temperature is lower than 1000°C, a stainless steel material including S304 is selected;

[0052] The high temperature alloy material of this embodiment is a nickel-based high temperature alloy material with a grade of GH3128, GH3536, GH3625 or GH4169;

[0053] S30. Perform 3D printing;

[0054] The use of 3D printing laser additive manufacturing technology for jetting panel printing requires that the printing equipment has the ability to print high-temperature alloy materials or stainless steel materials, the printing format covers the maximum outer dimensions of the jetting panel, and the printing height exceeds the sum of the jetting panel height and the substrate height;

[0055] Before 3D printing, the substrate is preheated several times, and the substrate preheating temperature is increased stepwise each time; the first preheating temperature of the substrate in this embodiment is 80° C., and the second preheating temperature is 120° C.;

[0056] The thickness of the 3D printing layer ranges from 0.03mm to 0.15mm; the thickness of the 3D printing layer in this embodiment is 0.05mm;

[0057] 3D printing methods include multi-laser simultaneous printing and multi-laser upwind field printing;

[0058] The 3D printing sequence is to complete the multi-laser printing of the downwind format of the parts, and then proceed to the multi-laser printing of the upwind format;

[0059] S40. Remove powder;

[0060] After 3D printing is completed, wait for the substrate and the injection panel to cool to a safe temperature, remove the printed part of the substrate and the injection panel combination from the printing device, and then fix the printed part on the powder cleaning platform;

[0061] When the powder cleaning platform is working, the working conditions are argon atmosphere, room temperature, and pressure not higher than 2MPa. The residual powder of the printed part is removed by rotation and vibration.

[0062] After the printed part is cleaned of powder, use a plug gauge that matches the circular through hole, injection hole I, injection hole II, and injection hole III to check the circular through hole, injection hole I, injection hole II, and injection hole III one by one to ensure that there is no residual powder;

[0063] S50. Perform heat treatment;

[0064] Improve the density of printed parts and eliminate thermal stress through heat treatment;

[0065] The heat treatment process is as follows: vacuumize, heat up to A℃ at a given rate a℃ / min, and keep warm for a predetermined time; then heat up to B℃ at a given rate b℃ / min, and keep warm for a predetermined time; then fill with protective gas for partial pressure treatment; then gradually cool down and cool the printed part to room temperature; finally, vacuumize and keep for a predetermined time before taking it out of the oven;

[0066] Among them, a℃ / min, A℃, b℃ / min and B℃ are all pre-set values ​​according to the process requirements;

[0067] S60. Perform mechanical processing;

[0068] Machining of printed parts according to the requirements of injection panel assembly, sealing and installation;

[0069] The machining process is as follows: separate the injection panel and the substrate by wire cutting; remove the injection panel support structure; remove the 3D printing structure design margin of the injection panel; remove the 3D printing deformation margin of the injection panel; process the sealing structure of the injection panel; process the positioning structure of the injection panel; process the connection slot of the injection panel; process the installation slot of the inner nozzle in the outer nozzle connection cylinder 3;

[0070] Machining equipment includes five-axis CNC lathes, milling machines and horizontal lathes;

[0071] The operating temperature of machining is room temperature and the operating pressure is atmospheric pressure;

[0072] S70. Trial assembly of blind nozzle 8;

[0073] The blind nozzle 8 is trial-assembled in the mounting slot of each outer nozzle connecting cylinder 3. If problems such as thread mismatch, inadequate installation, and too small a gap occur during the trial assembly, the mounting slot of the outer nozzle connecting cylinder 3 needs to be repaired for the second time;

[0074] The equipment used for secondary repair includes wrenches, taps and files; the operating temperature of secondary repair is room temperature and the operating pressure is atmospheric pressure;

[0075] S80. Conduct airtightness test;

[0076] In order to test the overall sealing performance of the injection panel, an injection panel airtightness test is carried out; Figure 3 As shown, the tooling structure of the airtight test includes an airtight tooling upper cover plate 6 and an airtight tooling lower cover plate 7, an air inlet nozzle 9 is installed on the airtight tooling lower cover plate 7, and the air inlet nozzle 9 is externally connected to a nitrogen bottle;

[0077] The airtight test process is as follows: blind nozzles 8 are installed in the mounting slots of the inner nozzles in the outer nozzle connecting cylinders 3 of the injection panel respectively; a sealing ring A13 is placed in a sealing structure of the injection panel; the injection panel is fixed on the upper cover plate 6 of the airtight tooling by connecting screws A11; a sealing ring B12 is placed in another sealing structure of the injection panel; the upper cover plate 6 of the airtight tooling and the lower cover plate 7 of the airtight tooling are connected by connecting screws B14 to obtain an assembly; the assembly is placed on the operating table with the upper cover plate 6 of the airtight tooling facing upward and the lower cover plate 7 of the airtight tooling facing downward; water 10 is added to the groove above the normal temperature side panel 2 of the assembly, and the water 10 has a level higher than the sealing ring A13, and the high-pressure nitrogen in the nitrogen bottle is passed into the air inlet nozzle 9 to observe whether bubbles appear on the water surface within a predetermined time. If no bubbles appear within the predetermined time, the injection panel is qualified, and the 3D printing process of the injection panel is completed;

[0078] In this embodiment, the sealing ring A13 is an energy storage spring sealing ring; the sealing ring B12 is an O-ring;

[0079] In this embodiment, when the high-pressure nitrogen is 2MPa, if no bubbles appear on the water surface within 5 minutes, it is qualified;

[0080] S90. Complete assembly;

[0081] Disassemble the assembly, remove the blind nozzle 8, and install the inner nozzles in the mounting slots of the outer nozzle connecting cylinders 3 of the injection panel to obtain the injection panel assembly; install the injection panel assembly on the combustion heater through the flange, and repair it until it meets the use requirements.

[0082] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and the embodiments, and can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional improvements and modifications can be easily realized without departing from the principles of the present invention. Therefore, without departing from the general concept defined by the claims and equivalent scope, the present invention is not limited to the specific details and the illustrations shown and described here.

Claims

1. A 3D printing method for injection molding panels, characterized in that: The following steps are involved: S10. Design injection panel; The injection panel comprises a disc-shaped gas side panel (1) located at the top and a disc-shaped normal temperature side panel (2) located at the bottom; a plurality of outer nozzle connection cylinders (3) symmetrically distributed in a central direction are arranged between the gas side panel (1) and the normal temperature side panel (2); an inner nozzle is installed in the outer nozzle connection cylinder (3); a plurality of supporting rib square columns (4) evenly distributed along the circumferential direction are arranged on the side surfaces of the gas side panel (1) and the normal temperature side panel (2); cylindrical partitions (5) protruding from the surface of the gas side panel (1) are arranged on six radii evenly distributed along the circumferential direction above the gas side panel (1); and an upwardly protruding flange is arranged in the circumference of the gas side panel (1) for fixedly connecting the injection panel to the combustion heater; A circular through hole is provided on the central axis of each outer nozzle connection cylinder (3) for circulating the oxidant; a plurality of injection holes I are evenly distributed around the outer nozzle connection cylinder (3) and are provided on the circumference of each outer nozzle connection cylinder (3) for injecting the oxidant; a plurality of injection holes II arranged in a ring shape are designed on the surface of each cylindrical partition (5) for injecting the oxidant, so as to provide thermal protection for the cylindrical partition (5) in a gas environment; a plurality of injection holes III are evenly distributed along the circumference at the edge of the gas side panel (1) for injecting the oxidant, so as to provide thermal protection for the inner wall surface of the flange; S20. Determine 3D printing materials; The 3D printing material of the injection panel is determined according to the ambient temperature of the gas side panel (1). If the ambient temperature is higher than 1000°C, a high-temperature alloy material is selected; if the ambient temperature is lower than 1000°C, a stainless steel material including S304 is selected; S30. Perform 3D printing; The use of 3D printing laser additive manufacturing technology for jetting panel printing requires that the printing equipment has the ability to print high-temperature alloy materials or stainless steel materials, the printing format covers the maximum outer dimensions of the jetting panel, and the printing height exceeds the sum of the jetting panel height and the substrate height; Before 3D printing, the substrate is preheated several times, and the substrate preheating temperature rises in steps each time; The thickness of 3D printing layers ranges from 0.03mm to 0.15mm; 3D printing methods include multi-laser simultaneous printing and multi-laser upwind field printing; The 3D printing sequence is to complete the multi-laser printing of the downwind format of the parts, and then proceed to the multi-laser printing of the upwind format; S40. Remove powder; After 3D printing is completed, wait for the substrate and the injection panel to cool to a safe temperature, remove the printed part of the substrate and the injection panel combination from the printing device, and then fix the printed part on the powder cleaning platform; When the powder cleaning platform is working, the working conditions are argon atmosphere, room temperature, and pressure not higher than 2MPa. The residual powder of the printed part is removed by rotation and vibration. After the printed part is cleaned of powder, use a plug gauge that matches the circular through hole, injection hole I, injection hole II, and injection hole III to check the circular through hole, injection hole I, injection hole II, and injection hole III one by one to ensure that there is no residual powder; S50. Perform heat treatment; Improve the density of printed parts and eliminate thermal stress through heat treatment; The heat treatment process is as follows: vacuumize, heat up to A℃ at a given rate a℃ / min, and keep warm for a predetermined time; then heat up to B℃ at a given rate b℃ / min, and keep warm for a predetermined time; then fill with protective gas for partial pressure treatment; then gradually cool down and cool the printed part to room temperature; finally, vacuumize and keep for a predetermined time before taking it out of the oven; Among them, a℃ / min, A℃, b℃ / min and B℃ are all pre-set values ​​according to the process requirements; S60. Perform mechanical processing; Machining of printed parts according to the requirements of injection panel assembly, sealing and installation; The machining process is as follows: separating the injection panel and the substrate by wire cutting; removing the injection panel support structure; removing the 3D printing structure design margin of the injection panel; removing the 3D printing deformation margin of the injection panel; machining the sealing structure of the injection panel; machining the positioning structure of the injection panel; machining the connection slot of the injection panel; machining the installation slot of the inner nozzle in the outer nozzle connection cylinder (3); Machining equipment includes five-axis CNC lathes, milling machines and horizontal lathes; The operating temperature of machining is room temperature and the operating pressure is atmospheric pressure; S70. Trial assembly of the blind nozzle (8); The blind nozzle (8) is trial-assembled in the installation slot of each external nozzle connecting cylinder (3). If problems such as thread mismatch, improper installation, and too small a gap occur during the trial assembly, the installation slot of the external nozzle connecting cylinder (3) needs to be repaired again; The equipment used for secondary repair includes wrenches, taps and files; the operating temperature of secondary repair is room temperature and the operating pressure is atmospheric pressure; S80. Conduct airtightness test; In order to test the overall sealing performance of the injection panel, an injection panel airtightness test is performed; the tooling structure of the airtightness test includes an airtight tooling upper cover plate (6) and an airtight tooling lower cover plate (7); an air inlet nozzle (9) is installed on the airtight tooling lower cover plate (7), and the air inlet nozzle (9) is externally connected to a nitrogen bottle; The airtightness test process is as follows: blind nozzles (8) are respectively installed in the mounting slots of the inner nozzles in the outer nozzle connecting cylinders (3) of the injection panel; a sealing ring A (13) is placed in a sealing structure of the injection panel; the injection panel is fixed to the upper cover plate (6) of the airtight tooling by connecting screws A (11); a sealing ring B (12) is placed in another sealing structure of the injection panel; the upper cover plate (6) of the airtight tooling and the lower cover plate (7) of the airtight tooling are connected by connecting screws B (14) to obtain a combined The assembly is placed on the operating table in a direction in which the upper cover plate (6) of the airtight tooling faces upward and the lower cover plate (7) of the airtight tooling faces downward; water (10) is added into the groove above the normal temperature side panel (2) of the assembly, the water (10) having a level higher than the sealing ring A (13); high-pressure nitrogen in the nitrogen bottle is passed into the air inlet nozzle (9); and it is observed whether bubbles appear on the water surface within a predetermined time. If no bubbles appear within the predetermined time, the injection panel processing is qualified, and the 3D printing processing of the injection panel is completed; The pressure range of high-pressure nitrogen is 1MPa~3MPa; S90. Complete assembly; The assembly is disassembled, the blind nozzle (8) is removed, and the inner nozzles are respectively installed in the installation slots of the outer nozzle connecting cylinders (3) of the injection panel to obtain the injection panel assembly; the injection panel assembly is installed on the combustion heater through the flange plate, and repaired until it meets the use requirements.

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