A co-feed air three-stage variable-flow streamline gas-assisted 3D printing nozzle

Abstract

The application discloses a same-direction air intake three-stage variable-speed streamline gas-assisted 3D printing nozzle, which comprises a gas-assisted nozzle and a consumable nozzle; the inside is provided with gas flow channels I-VII arranged in sequence from top to bottom and communicated, and is simultaneously provided with consumable channels I-VI arranged in sequence from top to bottom and communicated; the gas flow channel II, the gas flow channel III and the gas flow channel V are all cylindrical structures, and the diameters are sequentially reduced; the gas flow channel IV, the gas flow channel V, the gas flow channel VI and the gas flow channel VII are all arranged in the gas-assisted nozzle, and the lower end of the gas flow channel VII is the outlet of the gas-assisted nozzle; the consumable channel III, the consumable channel IV, the consumable channel V and the consumable channel VI are all arranged in the consumable nozzle, and the lower end of the consumable channel VI is the outlet of the consumable nozzle; the lower section of the consumable nozzle is inserted into the gas flow channel VI, and the two enclose a streamline gas channel; the center of the outlet of the gas-assisted nozzle and the consumable nozzle is on the same vertical shaft. The application can improve the size precision and surface finish of the FDM printing part.

Description

Technical Field

[0001] This invention relates to the field of 3D technology, and in particular to a streamlined gas-assisted 3D printing nozzle with three-stage variable speed and unidirectional air intake. Background Technology

[0002] In recent years, with the rapid development of the manufacturing industry, 3D printing technology (additive manufacturing technology) has also been constantly innovating. This technology transforms 3D model designs into realistic 3D prototypes through a layer-by-layer accumulation process. Compared with traditional manufacturing methods, 3D printing technology has advantages such as low cost, short manufacturing time, and the ability to process complex parts, and therefore has been widely used in aerospace, biomedicine, automotive, and other fields.

[0003] Fused Deposition Modeling (FDM) is a typical layer-by-layer printing technology and a moldless forming technology, which can easily achieve personalized customization of complex models. However, FDM-printed parts have some problems, such as poor interlayer bonding strength, poor precision, and poor surface roughness, which restricts the application of this technology in the manufacturing of precision medical devices.

[0004] To address these issues, CN105235220A discloses a gas-assisted extrusion head for an FDM 3D printer. This approach introduces gas into the 3D printing process, but it doesn't adequately consider the interaction between the gas and the polymer, leading to eddies and uneven extrusion. In smaller extrusion channels, this can cause surface defects such as bubbles or ridges during extrusion, resulting in poor dimensional accuracy and surface finish of the FDM printed parts, which still require further improvement. Therefore, continued research and improvement are needed to overcome the limitations of large-scale applications of FDM technology in biomedicine and industrial processing. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and to provide a streamlined gas-assisted 3D printing nozzle with three-stage variable speed and unidirectional air intake.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A streamlined gas-assisted 3D printing nozzle with three-stage variable speed and unidirectional air intake, comprising a gas-assisted nozzle and a consumable nozzle;

[0008] The internal structure of the unidirectional air intake three-stage variable speed streamlined gas-assisted 3D printing nozzle has gas flow channels I to VII arranged sequentially from top to bottom and connected, and also has consumable channels I to VI arranged sequentially from top to bottom and connected.

[0009] Gas channels II, III, V, VI, and VII are all rotating structures, with their central axes coinciding and being vertical. Gas channels II, III, and V are cylindrical structures, with their diameters decreasing sequentially. Gas channel VI is an inverted conical structure. The combination of gas channels II, III, and V allows the gas to form a cylindrical envelope, which is beneficial for forming a protective layer at the junction with the molten wire.

[0010] Consumable channel IV, consumable channel V, and consumable channel VI are all rotating structures, with their central axes coinciding and being vertical; consumable channel V has an inverted frustum-shaped structure.

[0011] The consumable nozzle consists of an upper section, a middle section, and a lower section, with the lower section being a hollow inverted cone shape.

[0012] Gas flow channels IV, V, VI, and VII are all located inside the gas-assisted nozzle, with the lower end of gas flow channel VII serving as the outlet of the gas-assisted nozzle; consumable channels III, IV, V, and VI are all located inside the consumable nozzle, with the lower end of consumable channel VI serving as the outlet of the consumable nozzle.

[0013] The lower section of the consumable nozzle is inserted into the gas flow channel VI, and the two form a streamlined gas channel. The center of the outlet of the consumable nozzle and the outlet of the gas-assisted nozzle are on the same vertical axis, and the outlet of the consumable nozzle is located 3-4 mm above the outlet of the gas-assisted nozzle. This ensures the continuity of the gas flow protective layer formed on the melt surface.

[0014] As a preferred technical solution:

[0015] As described above, a streamlined gas-assisted 3D printing nozzle with three-stage variable speed and unidirectional air intake has two cylindrical gas channels I, symmetrically distributed on both sides of the consumable nozzle.

[0016] Gas channel IV has an inverted frustum-shaped structure. The diameter of the large end of gas channel IV is smaller than that of gas channel III, and the diameter of the small end of gas channel IV is the same as that of gas channel V.

[0017] Gas channel VII has a frustum-shaped structure; the upper diameter of gas channel VI is the same as the diameter of gas channel V, and the lower diameter of gas channel VI is the same as the small end diameter of gas channel VII.

[0018] Consumable channel I and consumable channel III are both inverted frustum-shaped structures, consumable channel II is a frustum-shaped structure, the small end diameter of consumable channel I and the large end diameter of consumable channel III are the same as the diameter of consumable channel II, and the small end diameter of consumable channel III is the same as the diameter of consumable channel IV.

[0019] Consumable channel IV and consumable channel VI are cylindrical structures; the upper diameter of consumable channel V is the same as the diameter of consumable channel IV, and the lower diameter of consumable channel V is the same as the diameter of consumable channel VI.

[0020] The consumable nozzle consists of a coaxial hollow cylindrical upper section, a hollow cylindrical middle section, and a hollow inverted conical lower section;

[0021] The gas-assisted nozzle consists of a cylindrical section and an inverted frustum section, with the cylindrical section located above the inverted frustum section.

[0022] As described above, in a unidirectional air intake three-stage variable speed streamlined gas-assisted 3D printing nozzle, part of the middle section of the consumable nozzle is located in gas flow channel II, gas flow channel III, gas flow channel IV, and gas flow channel V, and another part is located in gas flow channel VI.

[0023] Consumable channel III is located in the middle section of the consumable nozzle, part of consumable channel IV is located in the middle section of the consumable nozzle and another part is located in the lower section of the consumable nozzle, and consumable channels V and VI are both located in the lower section of the consumable nozzle.

[0024] Gas flow channels IV and V are both located within the cylindrical section of the gas-assisted nozzle, while gas flow channels VI and VII are both located within the inverted frustum section of the gas-assisted nozzle.

[0025] As described above, for a three-stage variable-speed streamlined gas-assisted 3D printing nozzle with co-current air intake, the overall size of the 3D printing nozzle needs to be considered. A smaller overall size can provide a faster response time and heating speed, while a larger overall size can provide a larger heating surface area and a more stable heating effect. Each gas channel is included within the overall size. The diameter of gas channel II is 2.5 to 2.6 times the outer diameter of the middle section of the filament nozzle, the diameter of gas channel III is 1.8 to 2 times the outer diameter of the middle section of the filament nozzle, the diameter of gas channel V is 1.2 to 1.4 times the outer diameter of the middle section of the filament nozzle, the lower end diameter of gas channel VI is 0.2 to 0.3 mm larger than the outlet of the filament nozzle, and the large end diameter of gas channel VII is more than 0.1 mm larger than the lower end diameter of gas channel VI.

[0026] As described above, a streamlined gas-assisted 3D printing nozzle with three-stage variable speed and unidirectional air intake has two gas channels I, which are the hollow parts of an air intake pipe one and an air intake pipe two, respectively.

[0027] The above-described unidirectional air intake three-stage variable speed streamlined gas-assisted 3D printing nozzle also includes an upper plate and a lower plate, which are assembled as the main body of the gas-assisted 3D printing nozzle; the upper plate and the lower plate are placed horizontally, with the upper plate located above the lower plate, and the two are detachably connected (specifically assembled by screws and pins);

[0028] Gas flow channel II is installed on the upper plate, and gas flow channel III is installed on the lower plate; the bottoms of air inlet pipe I and air inlet pipe II are vertically inserted into the upper plate; the upper section of the consumable nozzle is vertically inserted into the upper plate; the cylindrical section of the gas auxiliary nozzle is vertically inserted into the lower plate, and the upper surface of the hexagon is in contact with the lower surface of the lower plate.

[0029] As described above, a streamlined gas-assisted 3D printing nozzle with three-stage variable speed and unidirectional air intake has a sensor hole on the upper plate for connecting a temperature sensor to identify the temperature, and a heating hole on the lower plate for connecting a heating rod to provide heating.

[0030] The aforementioned three-stage variable speed streamlined gas-assisted 3D printing nozzle with unidirectional air intake also includes a consumable conduit; both consumable channel I and consumable channel II are hollow portions of the consumable conduit; the top of the consumable conduit is a hollow cylindrical structure for connecting with the printer, and the bottom of the consumable conduit is inserted into the upper section of the consumable nozzle and threadedly connected to it.

[0031] As described above, a streamlined gas-assisted 3D printing nozzle with three-stage variable speed and co-current air intake has an annular plate b fixedly fitted on the filament conduit, the lower surface of the annular plate b being flush with the upper surface of the upper plate; an annular plate a fixedly fitted on the middle section of the filament nozzle, the upper surface of the annular plate a being flush with the upper surface of the middle section of the filament nozzle; a reinforcing rib for fixing the filament nozzle is provided on the gas flow channel VI; a hexagonal body is fixedly fitted on the cylindrical section of the gas-assisted nozzle, the lower surface of the hexagonal body being flush with the upper surface of the inverted frustum section of the gas-assisted nozzle.

[0032] The principle of this invention is as follows:

[0033] The purpose of this invention is to solve the problems existing in CN105235220A and improve the dimensional accuracy and surface finish of FDM printed parts. The specific principle is as follows:

[0034] This invention designs gas channels I-VII and filament channels I-VI, allowing the gas and filament to enter the nozzle in the same direction and undergo changes within their respective channels to reach a stable state. The dimensional accuracy of FDM printed parts largely depends on the appearance of the filament bonding and extrusion process. Inside the 3D printing nozzle, the filament melt is at a high temperature and in a viscous flow state. The melt has a low modulus and poor resistance to deformation. In CN105235220A, the airflow is perpendicular to or intersects with the melt filament. When the airflow merges with the melt, the high-pressure gas generates a normal force on the surface of the high-temperature melt. This force acting on the melt surface causes changes in the size and appearance of the printed part. Therefore, the dimensional accuracy of FDM printed parts in CN105235220A is low. Since the gas and filament enter the nozzle in the same direction, this invention will improve the dimensional accuracy of FDM printed parts.

[0035] Gas enters through gas channel I. Since "gas channels II, III, and V are all cylindrical structures, with their diameters decreasing sequentially," the following can be achieved: ① It can reduce the resistance of gas passing through the channels, because the airflow velocity gradually increases in the narrowing section of the channel. This increase in velocity reduces the resistance experienced by the gas within the channel, thereby improving the channel's transmission efficiency; ② It can increase the velocity of the gas passing through the channels. The reduced diameter increases the gas flow rate, increasing the gas velocity within the channel, which in turn increases the channel's flow rate; ③ It can reduce noise and vibration. If the channel diameter were directly reduced to the target diameter, the sudden reduction would cause a surge in gas flow velocity, generating noise and vibration as the airflow passes through the channel. The three-stage progressively narrowing design can reduce noise and vibration during gas flow, minimizing the impact on the environment and equipment. The three-stage progressive shrinkage design helps transform chaotic and disordered airflow into a stable and sufficient flow into the gas channel VI, avoiding the adverse effects of chaotic and disordered airflow on the dimensional accuracy and surface finish of FDM printed parts. Chaotic and disordered airflow can lead to uneven material extrusion. During the printing process, chaotic and disordered airflow cannot evenly assist the required position, resulting in unevenness or gaps on the surface of the printed parts, which can also lead to a decrease in accuracy. The instability of airflow can cause deviation during the printing process, which in turn affects the printing accuracy and size, and also leads to a decrease in surface finish. Disordered and chaotic airflow may cause defects such as particles, uneven textures or bubbles on the surface of the printed parts, affecting their appearance and texture.

[0036] This invention designs a "lower section of the consumable nozzle inserted into the gas flow channel VI, the two forming a streamlined gas channel". In gas-assisted 3D printing, the use of a streamlined gas channel can effectively improve printing quality and efficiency. The specific reasons are: ① The streamlined gas channel can effectively prevent drastic changes in airflow direction and leakage, allowing the airflow to be evenly distributed throughout the channel, effectively avoiding eddies and uneven extrusion; ② In the streamlined gas channel, the gas can flow through the shortest path, thereby reducing energy and time waste; ③ When the airflow passes through the streamlined gas channel, friction and resistance are also reduced, thereby increasing the airflow speed and flow rate.

[0037] After entering consumable channel II, the consumable becomes molten. Since "consumable channel V has an inverted frustum structure", the consumable will be compressed as it flows through consumable channel V and eventually squeezed out from consumable channel VI.

[0038] Because "the outlet of the filament nozzle is located 3-4 mm above the outlet of the gas-assisted nozzle", the airflow will wrap the molten filament extruded from the filament channel VI to form a continuous high-temperature airflow protective layer, which is then extruded from the airflow channel VII in a completely sliding manner. This effectively solves the surface defects such as surface bubbles or ridges that occur during the extrusion process, thereby improving the surface finish of the FDM printed parts. In contrast, in CN105235220A, gas participates in pushing the molten polymer filament to be extruded through a smaller extrusion channel. Surface defects such as surface bubbles or ridges will occur during the extrusion process in the narrow channel, thus reducing the surface finish of the FDM printed parts.

[0039] Beneficial effects:

[0040] (1) The gas-assisted 3D printing nozzle with three-stage variable speed and co-current air intake of the present invention introduces gas-assisted processing into 3D printing, so that the gas and the consumable enter and exit in the same direction. The gas enters the three-stage variable speed gas channel, so that the airflow gradually contracts according to the design path and converges with the molten consumable at the outlet of the consumable nozzle, which facilitates the formation of a protective layer that wraps the melt and improves the product quality of the printed parts.

[0041] (2) The same-direction air intake three-stage variable speed streamlined gas-assisted 3D printing nozzle of the present invention has a streamlined gas channel around the lower section of the consumable nozzle, which ensures that when the gas contacts the consumable, the gas on the inner wall of the gas-assisted nozzle and the consumable form a thin gas protective layer. The gas wraps the consumable and is extruded in parallel, forming a gas protective layer, which eliminates the extrusion expansion of the consumable at the nozzle outlet, reduces the layer thickness, and thus improves the dimensional accuracy and surface roughness of the printed parts.

[0042] (3) In order to meet the 3D printing processing accuracy, the three-stage variable speed streamlined gas-assisted 3D printing nozzle of the present invention requires an effective positioning structure to ensure that the outlet of the consumable nozzle and the center of the outlet of the gas-assisted nozzle are on the same vertical axis. In the present invention, the annular plate a and the annular plate b are firmly connected to the upper plate, and the gas flow channel VI is provided with reinforcing ribs for fixing the consumable nozzle. The two work together to make the outlet of the consumable nozzle and the center of the outlet of the gas-assisted nozzle on the same vertical axis. Attached Figure Description

[0043] Figure 1 This is an exploded structural diagram of the assembly drawing of the present invention;

[0044] Figure 2 This is a cross-sectional view of the main view of the assembly drawing of the present invention;

[0045] Figure 3 This is a top view of the assembly diagram of the present invention;

[0046] Figure 4 This is a lower view of the assembly diagram of the present invention;

[0047] Figure 5 Figure 1 is a schematic diagram of the consumable nozzle and gas-assisted nozzle structure of the present invention; Figure 2 is a schematic diagram of the consumable nozzle and gas-assisted nozzle structure, and Figure 3 is a partially enlarged view of the consumable nozzle and gas-assisted nozzle.

[0048] Figure 6 Figure 1 is a schematic diagram of the consumable conduit and consumable nozzle structure of the present invention; Figure 2e is a schematic diagram of the consumable conduit and consumable nozzle disassembled, and Figure 3f is a schematic diagram of the consumable conduit and consumable nozzle assembled.

[0049] Figure 7 Figure 1 is a schematic diagram of the gas-assisted nozzle of the present invention; Figure 2g is a bottom view of the gas-assisted nozzle, and Figure 3h is a cross-sectional view of the gas-assisted nozzle.

[0050] Figure 8 Figure a is a schematic diagram of the gas flow channel and consumable channel of the present invention; Figure b is a schematic diagram of the gas flow channel and Figure a is a schematic diagram of the consumable channel.

[0051] Figure 9 This is a schematic diagram of the overall structure of the present invention;

[0052] Among them, 1-Consumable conduit, 2-Inlet pipe one, 3-Inlet pipe two, 4-Screw, 5-Upper plate, 6-Pin, 7-Consumable nozzle, 8-Lower plate, 9-Gas auxiliary nozzle, 10-Heating hole, 12-Sensor hole, 13-Gas flow channel I, 14-Gas flow channel II, 15-Gas flow channel III, 16-Gas flow channel IV, 17-Gas flow channel V, 18-Gas flow channel VI, 19-Gas flow channel VII, 20-Consumable channel I, 21-Consumable channel II, 22-Consumable channel III, 23-Consumable channel IV, 24-Consumable channel V, 25-Consumable channel VI, 101-Air compressor, 102-Air valve, 103-Flow meter, 104-Pressure gauge, 105-Regulating valve, 106-Throttle valve, 107-Gas heater. Detailed Implementation

[0053] The technical solutions of the present invention will now be clearly and completely described in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0054] A streamlined gas-assisted 3D printing nozzle with three-stage variable speed and co-current air intake, such as Figure 1 , 2 As shown, it includes a consumable nozzle 7, a gas-assisted nozzle 9, an upper plate 5, a lower plate 8, a consumable conduit 1, an annular plate a, and an annular plate b;

[0055] The internal structure of the unidirectional air intake three-stage variable speed streamlined gas-assisted 3D printing nozzle has gas flow channels I to VII arranged sequentially from top to bottom and connected, and also has consumable channels I to VI arranged sequentially from top to bottom and connected.

[0056] The lengths of gas flow channels I to VII are 10 mm, 3–5 mm, 6–8 mm, 1 mm, 5 mm, 7 mm, and 0.5 mm, respectively.

[0057] The lengths of consumable channels I to VI are 1mm, 15mm, 1.5mm, 15-17mm, 1.5mm, and 1-2mm, respectively.

[0058] like Figure 8 As shown in a, gas channels I to VII are all rotating structures, and the central axes of gas channels II to VII coincide and are vertical axes.

[0059] Gas flow channel I is a cylindrical structure with a diameter of 1.5 mm, and there are 2 of them;

[0060] Gas flow channel II, gas flow channel III, and gas flow channel V are all cylindrical structures, with diameters of 15 mm, 10 mm, and 7 mm, respectively.

[0061] Gas channel IV has an inverted frustum-shaped structure. The diameter of the large end of gas channel IV is 7 mm, and the diameter of the small end of gas channel IV is the same as the diameter of gas channel V.

[0062] Gas flow channel VI has an inverted conical structure, and the upper diameter of gas flow channel VI is the same as the diameter of gas flow channel V.

[0063] Gas channel VII has a frustum-shaped structure. The diameter of the small end of gas channel VII is 0.6-0.7 mm, the same as the lower end diameter of gas channel VI. The diameter of the large end of gas channel VII is 0.7-0.8 mm, which is more than 0.1 mm larger than the lower end diameter of gas channel VI.

[0064] like Figure 8 As shown in b, all six consumable channels I to VI are rotating structures, with their central axes coinciding and being vertical axes.

[0065] Both consumable channel I and consumable channel III have an inverted frustum-shaped structure, with the large end diameter of consumable channel I being 2.9–3.1 mm;

[0066] Consumable channel II has a frustum-shaped structure with a diameter of 2.8–3 mm. The diameter of the small end of consumable channel I and the diameter of the large end of consumable channel III are the same as the diameter of consumable channel II.

[0067] Consumable channel IV and consumable channel VI are cylindrical structures with diameters of 2 mm and 0.4–1.0 mm, respectively. The diameter of consumable channel IV is the same as the small end diameter of consumable channel III.

[0068] The consumable channel V has an inverted frustum-shaped structure. The upper diameter of the consumable channel V is the same as the diameter of the consumable channel IV, and the lower diameter of the consumable channel V is the same as the diameter of the consumable channel VI.

[0069] like Figure 2 , 5 As shown, the consumable nozzle 7 consists of a coaxial hollow cylindrical upper section (outer diameter 6mm, length 5mm), a hollow cylindrical middle section (outer diameter 4mm, length 15-17mm), and a hollow inverted conical lower section (upper end outer diameter 4mm, lower end outer diameter 0.4-1mm, length 2.5-4mm);

[0070] Two gas flow channels I are symmetrically distributed on both sides of the consumable nozzle 7, which are the hollow parts of an air inlet pipe 1 2 and the hollow parts of an air inlet pipe 2 3 respectively.

[0071] The middle section of the consumable nozzle 7 is located in gas flow channel II, gas flow channel III, gas flow channel IV, and gas flow channel V, and another part is located in gas flow channel VI.

[0072] The diameter of gas flow channel II is 2.5 to 2.6 times the outer diameter of the middle section of consumable nozzle 7; the diameter of gas flow channel III is 1.8 to 2 times the outer diameter of the middle section of consumable nozzle 7; the diameter of gas flow channel V is 1.2 to 1.4 times the outer diameter of the middle section of consumable nozzle 7; and the lower end diameter of gas flow channel VI is 0.2 to 0.3 mm larger than the outlet of consumable nozzle 7.

[0073] Consumable channel III is located in the middle section of consumable nozzle 7. Part of consumable channel IV is located in the middle section of consumable nozzle 7, and another part is located in the lower section of consumable nozzle 7. Consumable channels V and VI are both located in the lower section of consumable nozzle 7. The lower end of consumable channel VI is the outlet of consumable nozzle 7.

[0074] The lower section of the consumable nozzle 7 is inserted into the gas flow channel VI, and the two form a streamlined gas channel. The consumable nozzle 7 is fixed by reinforcing ribs provided on the gas flow channel VI.

[0075] like Figure 5 , 7 As shown, the gas-assisted nozzle 9 consists of a cylindrical section and an inverted frustum section, with the cylindrical section located above the inverted frustum section;

[0076] A hexagonal body is fixedly fitted on the cylindrical section of the gas-assisted nozzle 9, and the lower surface of the hexagonal body is flush with the upper surface of the inverted frustum section of the gas-assisted nozzle 9.

[0077] Gas flow channels IV and V are both located within the cylindrical section of the gas-assisted nozzle 9, while gas flow channels VI and VII are both located within the inverted frustum section of the gas-assisted nozzle 9. The lower end of gas flow channel VII is the outlet of the gas-assisted nozzle 9.

[0078] The outlet of consumable nozzle 7 and the outlet of gas-assisted nozzle 9 are on the same vertical axis, and the outlet of consumable nozzle 7 is located 3-4 mm above the outlet of gas-assisted nozzle 9.

[0079] like Figures 2-4 As shown, the upper plate 5 and the lower plate 8 are placed horizontally, with the upper plate 5 located above the lower plate 8. The two are detachably connected by screws 4 and pins 6.

[0080] The upper plate 5 is provided with a sensor hole 12, the gas flow channel II is set on the upper plate 5, the bottom of the first air inlet pipe 2 and the second air inlet pipe 3 are vertically inserted into the upper plate 5, and the upper section of the consumable nozzle 7 is vertically inserted into the upper plate 5.

[0081] Heating holes 10 are provided on the lower plate 8, gas flow channel III is provided on the lower plate 8, and the cylindrical section of the gas auxiliary nozzle 9 is vertically inserted into the lower plate 8, with the upper surface of the hexagonal body fitting against the lower surface of the lower plate 8.

[0082] like Figure 6 As shown, the top of the consumable conduit 1 is a hollow cylinder, the hollow part of the consumable conduit 1 is the consumable channel I and the consumable channel II, and the bottom of the consumable conduit 1 is inserted into the upper section of the consumable nozzle 7 and threadedly connected to it.

[0083] The annular plate b is fixedly sleeved on the consumable conduit 1, and the lower surface of the annular plate b is in contact with the upper surface of the upper plate 5.

[0084] The annular plate a is fixedly fitted on the middle section of the consumable nozzle 7, and the upper surface of the annular plate a is flush with the upper surface of the middle section of the consumable nozzle 7.

[0085] Example 1

[0086] A streamlined gas-assisted 3D printing nozzle with three-stage variable speed and co-current air intake has the same structure as above. The length of gas channel II is 3 mm, the length of gas channel III is 6 mm, the length of filament channel IV is 15 mm, the small end diameter of gas channel VII is 1.2 mm, and the large end diameter of gas channel VII is 1.3 mm; the large end diameter of filament channel I is 3.1 mm, the diameter of filament channel II is 2.8 mm, and the diameter of filament channel VI is 1 mm.

[0087] The middle section of the consumable nozzle is 15mm long, and the lower section is 2.5mm long.

[0088] The lower outer diameter of the lower section of the consumable nozzle is 1 mm;

[0089] The diameter of gas channel II is 2.5 times the outer diameter of the middle section of the consumable nozzle, the diameter of gas channel III is 1.8 times the outer diameter of the middle section of the consumable nozzle, the diameter of gas channel V is 1.4 times the outer diameter of the middle section of the consumable nozzle, and the lower end diameter of gas channel VI is 0.2 mm larger than the outlet of the consumable nozzle.

[0090] The outlet of the consumable nozzle is located 3 mm above the outlet of the gas-assisted nozzle.

[0091] A 3D printing method employs the aforementioned co-current air intake, three-stage variable speed streamlined gas-assisted 3D printing nozzle, using 1.75mm diameter PLA filament (manufactured by Orcotec Technology Co., Ltd.). The method first sets the nozzle temperature and heated bed temperature of the 3D printer connected to the printing nozzle. Figure 1 , 9 As shown, the gas flows out from the air compressor 101, passes through the air valve 102, flow meter 103, and pressure gauge 104 to measure the initial gas flow rate and pressure, and then flows through the regulating valve 105, throttle valve 106, and gas heater 107 to pre-treat, heat, and pressurize the gas. The high-temperature, high-pressure gas is then divided into two paths, which enter the gas flow channels I to VII formed by the upper plate 5 and the lower plate 8 through the inlet pipe 2 and inlet pipe 3 inserted into the upper plate 5, respectively. The inner diameter of the airflow varies with the flow rate. As the gas flow channels I to VII gradually contract, the airflow eventually envelops the molten filament in the streamlined annular gas channel formed between the lower edge of the filament nozzle 7 and the inner flow channel of the gas auxiliary nozzle 9. The high-temperature and high-pressure gas then extrudes the molten filament in parallel, and finally, the molten filament and gas are deposited together on the surface of the printed part. Among these conditions, the regulating valve 105 has a gas pressure of 0.4 MPa, the throttle valve 106 has an airflow of 1.75 L / min, the gas heater temperature is 210℃, the 3D printer temperature is 210℃, and the heated bed temperature is 60℃.

[0092] The surface roughness Ra of the sample printed using the above method is 3.122 μm, and the dimensional accuracy shrinkage rate of the printed sample is 0.26%.

[0093] Comparative Example 1

[0094] A 3D printing method is basically the same as Example 1, except that Comparative Example 1 uses the 3D printing nozzle in patent CN105235220A.

[0095] The surface roughness Ra of the sample printed using the above method is 6.451 μm, and the dimensional accuracy shrinkage rate of the printed sample model is 0.82%.

[0096] Comparing Example 1 and Comparative Example 1, it can be seen that Comparative Example 1 uses a 3D printing nozzle of the prior art, and the surface roughness value Ra of Comparative Example 1 is higher than that of Example 1. The surface roughness and dimensional accuracy shrinkage rate of the sample of Comparative Example 1 are both higher than those of Example 1, while the surface roughness and dimensional accuracy of the sample printed in Example 1 are improved to varying degrees.

[0097] Example 2

[0098] A streamlined gas-assisted 3D printing nozzle with three-stage variable speed and co-current air intake has the same structure as above. The length of gas channel II is 4 mm, the length of gas channel III is 7 mm, the length of filament channel IV is 16 mm, the small end diameter of gas channel VII is 0.6 mm, and the large end diameter of gas channel VII is 0.7 mm; the large end diameter of filament channel I is 3.0 mm, the diameter of filament channel II is 2.9 mm, and the diameter of filament channel VI is 0.4 mm.

[0099] The middle section of the consumable nozzle is 16mm long, and the lower section is 3mm long;

[0100] The lower end outer diameter of the lower section of the consumable nozzle is 0.4 mm;

[0101] The diameter of gas channel II is 2.55 times the outer diameter of the middle section of the consumable nozzle, the diameter of gas channel III is 1.9 times the outer diameter of the middle section of the consumable nozzle, the diameter of gas channel V is 1.2 times the outer diameter of the middle section of the consumable nozzle, and the lower end diameter of gas channel VI is 0.2 mm larger than the outlet of the consumable nozzle.

[0102] The outlet of the consumable nozzle is located 4 mm above the outlet of the gas-assisted nozzle.

[0103] A 3D printing method employs a three-stage variable-speed streamlined gas-assisted 3D printing nozzle with co-current air intake, using PLA filament with a diameter of 1.75mm for printing. First, the nozzle temperature and heated bed temperature of the 3D printer connected to the printing nozzle are set. Then, gas flows from an air compressor, passing through a gas valve, flow meter, and pressure gauge to measure the initial gas flow rate and pressure. The gas then flows through a regulating valve, throttle valve, and gas heater for pretreatment, heating, and pressurization. The high-temperature, high-pressure gas is divided into two paths, each passing through an upper plate insert... The air inlet pipes 1 and 2 enter the annular variable-speed gas channel formed by the combination of the upper and lower plates. The inner diameter of the airflow gradually contracts with the annular variable-speed gas channel. The airflow eventually squeezes the molten consumable material out in parallel through the streamlined annular gas channel formed between the lower edge of the consumable nozzle and the inner flow channel of the gas auxiliary nozzle. The high-temperature and high-pressure gas envelops the molten consumable material and squeezes it out in parallel. The regulating valve 105 has a gas pressure of 0.4MPa, the throttle valve 106 has an airflow of 1.75L / min, the gas heater temperature is 210℃, the 3D printer temperature is 210℃, and the heated bed temperature is 60℃.

[0104] The samples printed using the above method have low surface roughness Ra and low dimensional shrinkage rate.

[0105] Example 3

[0106] A streamlined gas-assisted 3D printing nozzle with three-stage variable speed and co-current air intake has the same structure as above. The length of gas channel II is 5 mm, the length of gas channel III is 8 mm, the length of filament channel IV is 17 mm, the small end diameter of gas channel VII is 0.7 mm, and the large end diameter of gas channel VII is 0.8 mm; the large end diameter of filament channel I is 2.9 mm, the diameter of filament channel II is 3 mm, and the diameter of filament channel VI is 0.4 mm.

[0107] The middle section of the consumable nozzle is 17mm long, and the lower section is 4mm long;

[0108] The lower end outer diameter of the lower section of the consumable nozzle is 0.4 mm;

[0109] The diameter of gas channel II is 2.6 times the outer diameter of the middle section of the consumable nozzle, the diameter of gas channel III is 2 times the outer diameter of the middle section of the consumable nozzle, the diameter of gas channel V is 1.3 times the outer diameter of the middle section of the consumable nozzle, and the lower end diameter of gas channel VI is 0.3 mm larger than the outlet of the consumable nozzle.

[0110] The outlet of the consumable nozzle is located 4 mm above the outlet of the gas-assisted nozzle.

[0111] A 3D printing method employs a three-stage variable-speed streamlined gas-assisted 3D printing nozzle with co-current air intake, using PLA filament with a diameter of 1.75mm for printing. First, the nozzle temperature and heated bed temperature of the 3D printer connected to the printing nozzle are set. Then, gas flows from an air compressor, passing through a gas valve, flow meter, and pressure gauge to measure the initial gas flow rate and pressure. The gas then flows through a regulating valve, throttle valve, and gas heater for pretreatment, heating, and pressurization. The high-temperature, high-pressure gas is divided into two paths, each passing through an upper plate insert... The air inlet pipes 1 and 2 enter the annular variable-speed gas channel formed by the combination of the upper and lower plates. The inner diameter of the airflow gradually contracts with the annular variable-speed gas channel. The airflow eventually squeezes the molten consumable material out in parallel through the streamlined annular gas channel formed between the lower edge of the consumable nozzle and the inner flow channel of the gas auxiliary nozzle. The high-temperature and high-pressure gas envelops the molten consumable material and squeezes it out in parallel. The regulating valve 105 has a gas pressure of 0.4MPa, the throttle valve 106 has an airflow of 1.75L / min, the gas heater temperature is 210℃, the 3D printer temperature is 210℃, and the heated bed temperature is 60℃.

[0112] The samples printed using the above method have low surface roughness Ra and low dimensional shrinkage rate.

[0113] It should be noted that, in this document, relational terms such as "one" and "two" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0114] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A co-axial gas assisted 3D printing nozzle with three-stage variable flow line shape, characterized in that, The gas-assisted nozzle (9) and the consumable nozzle (7) are included. The inside of the co-current gas inlet three-stage variable flow line gas-assisted 3D printing nozzle is provided with gas flow channels I-VII arranged in sequence from top to bottom and connected, and is also provided with consumable channels I-VI arranged in sequence from top to bottom and connected. The gas flow channel II, the gas flow channel III, the gas flow channel V, the gas flow channel VI and the gas flow channel VII are all rotary body structures, the central axes of the five are coincident and are vertical axes; the gas flow channel II, the gas flow channel III and the gas flow channel V are cylindrical structures, the diameters of the gas flow channel II, the gas flow channel III and the gas flow channel V decrease in turn, and the gas flow channel VI is a reverse conical structure. The consumable channel IV, the consumable channel V and the consumable channel VI are all rotary body structures, the central axes of the three are coincident and are vertical axes; the consumable channel V is a reverse circular table structure. The consumable nozzle (7) is composed of an upper section, a middle section and a lower section, and the lower section is a hollow reverse conical structure. The gas flow channel IV, the gas flow channel V, the gas flow channel VI and the gas flow channel VII are all arranged in the gas-assisted nozzle (9), and the lower end of the gas flow channel VII is the outlet of the gas-assisted nozzle (9); the consumable channel III, the consumable channel IV, the consumable channel V and the consumable channel VI are all arranged in the consumable nozzle (7), and the lower end of the consumable channel VI is the outlet of the consumable nozzle (7); The lower section of the consumable nozzle (7) is inserted into the gas flow channel VI, and the two surround a flow line gas channel; the center of the outlet of the consumable nozzle (7) and the outlet of the gas-assisted nozzle (9) is on the same vertical axis, and the outlet of the consumable nozzle (7) is located 3-4 mm above the outlet of the gas-assisted nozzle (9).

2. A co-axial gas-assisted 3D printing nozzle according to claim 1, wherein, The gas flow channel I is a cylindrical structure, and the number is 2, which is symmetrically distributed on both sides of the consumable nozzle (7); The gas flow channel IV is a reverse circular table structure, the large end diameter of the gas flow channel IV is smaller than the diameter of the gas flow channel III, and the small end diameter of the gas flow channel IV is the same as the diameter of the gas flow channel V; The gas flow channel VII is a circular table structure; the upper end diameter of the gas flow channel VI is the same as the diameter of the gas flow channel V, and the lower end diameter of the gas flow channel VI is the same as the small end diameter of the gas flow channel VII; The consumable channel I and the consumable channel III are both reverse circular table structures, the consumable channel II is a circular table structure, the small end diameter of the consumable channel I and the large end diameter of the consumable channel III are both the same as the diameter of the consumable channel II, and the small end diameter of the consumable channel III is the same as the diameter of the consumable channel IV; The consumable channel IV and the consumable channel VI are cylindrical structures; the upper end diameter of the consumable channel V is the same as the diameter of the consumable channel IV, and the lower end diameter of the consumable channel V is the same as the diameter of the consumable channel VI; The consumable nozzle (7) is composed of a coaxial hollow cylindrical upper section, a coaxial hollow cylindrical middle section and a coaxial hollow reverse conical lower section; The gas-assisted nozzle (9) is composed of a cylindrical section and a reverse circular table section, and the cylindrical section is located above the reverse circular table section.

3. A co-axial gas-assisted 3D printing nozzle according to claim 2, wherein, A part of the middle section of the consumable nozzle (7) is located in the gas flow channel II, the gas flow channel III, the gas flow channel IV and the gas flow channel V, and the other part is located in the gas flow channel VI; The gas flow channel I is a cylindrical structure, and the number is 2, which is symmetrically distributed on both sides of the consumable nozzle (7); The consumable channel III is arranged in the middle section of the consumable nozzle (7), a part of the consumable channel IV is arranged in the middle section of the consumable nozzle (7), and another part is arranged in the lower section of the consumable nozzle (7), the consumable channel V and the consumable channel VI are both arranged in the lower section of the consumable nozzle (7); The gas flow channel IV and the gas flow channel V are both arranged in the cylindrical section of the gas auxiliary nozzle (9), and the gas flow channel VI and the gas flow channel VII are both arranged in the rounded table section of the gas auxiliary nozzle (9).

4. A co-axial gas-assisted 3D printing nozzle according to claim 3, wherein, The diameter of the gas flow channel II is 2.5-2.6 times of the outer diameter of the middle section of the consumable nozzle (7), the diameter of the gas flow channel III is 1.8-2 times of the outer diameter of the middle section of the consumable nozzle (7), the diameter of the gas flow channel V is 1.2-1.4 times of the outer diameter of the middle section of the consumable nozzle (7), the lower end diameter of the gas flow channel VI is 0.2-0.3 mm larger than the outlet of the consumable nozzle (7), and the large end diameter of the gas flow channel VII is more than 0.1 mm larger than the lower end diameter of the gas flow channel VI.

5. A co-axial gas-assisted 3D printing nozzle according to claim 3, wherein, The two gas flow channels I are the hollow parts of the gas inlet pipe one (2) and the gas inlet pipe two (3) respectively.

6. A co-axial gas-assisted 3D printing nozzle according to claim 5, wherein, It also includes an upper plate (5) and a lower plate (8); the upper plate (5) and the lower plate (8) are horizontally placed, the upper plate (5) is above the lower plate (8), and the two are detachably connected; The gas flow channel II is arranged on the upper plate (5), and the gas flow channel III is arranged on the lower plate (8); the bottom of the gas inlet pipe one (2) and the gas inlet pipe two (3) is vertically inserted into the upper plate (5); the upper section of the consumable nozzle (7) is vertically inserted into the upper plate (5); the cylindrical section of the gas auxiliary nozzle (9) is vertically inserted into the lower plate (8), and the upper surface of the hexahedron is attached to the lower surface of the lower plate (8).

7. A co-axial gas-assisted 3D printing nozzle according to claim 6, wherein, The upper plate (5) is provided with a sensor hole, and the lower plate (8) is provided with a heating hole (10).

8. A co-axial gas-assisted 3D printing nozzle according to claim 6, wherein, It also includes a consumable guide pipe (1); the consumable channel I and the consumable channel II are both hollow parts of the consumable guide pipe (1); the top of the consumable guide pipe (1) is a hollow cylindrical structure, and the bottom of the consumable guide pipe (1) is inserted into the upper section of the consumable nozzle (7) and is threadedly connected therewith.

9. A co-axial gas-assisted 3D printing nozzle according to claim 8, wherein, The consumable guide pipe (1) is fixedly sleeved with an annular plate b, the lower surface of the annular plate b is attached to the upper surface of the upper plate (5); the middle section of the consumable nozzle (7) is fixedly sleeved with an annular plate a, the upper surface of the annular plate a is flush with the upper surface of the middle section of the consumable nozzle (7); the gas flow channel VI is provided with a reinforcing rib for fixing the consumable nozzle (7); the cylindrical section of the gas auxiliary nozzle (9) is fixedly sleeved with a hexahedron, and the lower surface of the hexahedron is flush with the upper surface of the rounded table section of the gas auxiliary nozzle (9).

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