Airflow field air inlet rectifying device for 3D printer and control method thereof

Abstract

The application relates to an air flow field air inlet rectifying device for a 3D printer and a control method thereof, which comprises an air inlet shunt pipe, a honeycomb rectifier and a linear array rectifier. The air inlet shunt pipe is connected with the air inlet ends of the honeycomb rectifier and the linear array rectifier respectively. The air outlet ends of the honeycomb rectifier and the linear array rectifier are respectively in sealed communication with a printing cabin of the 3D printer. The combination design of the honeycomb rectifier and the linear array rectifier is adopted. The honeycomb rectifier is used for forcibly dividing the original high-speed turbulent flow into thousands of tiny flow channels when the original high-speed turbulent flow enters, eliminating the central high-speed area and the edge low-speed area, making the air flow distribution uniform, forming a main protective laminar flow and inhibiting air entrainment. The linear array rectifier is used for forming multiple columns of parallel and directional low-speed jets. The main protective laminar flow and the directional low-speed jets converge to form a stable cooperative circulation field in the printing cabin, realizing the dual goals of efficient removal of smoke and dust and aerodynamic stability of the powder bed.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing airflow field control technology, specifically relating to an airflow field inlet rectification device and its control method for a 3D printer. Background Technology

[0002] Additive manufacturing, or 3D printing, is better suited for creating complex-shaped parts compared to traditional processing methods. Selective laser melting (SLM) is the most popular technique in metal additive manufacturing. However, the complex heat conduction process in SLM often results in spatter generation. This spatter can affect the porosity, defects, and surface roughness of the printed part, thus impacting manufacturing stability, energy efficiency, and part quality. The protective gas flow within the printing chamber not only provides shielding but also removes byproducts of the laser manufacturing process, such as spatter and welding fumes. When spatter cannot be carried away by the protective gas flow and falls into the powder bed, it may be remelted by the laser, becoming inclusions that ultimately affect the mechanical properties of the printed part. Therefore, the flow rate of the protective gas within the printing chamber should be as high and stable as possible.

[0003] Existing technologies often employ single-grid or straight-tube rectifiers to deliver protective airflow. However, the airflow at the inlet tends to form a high-speed zone in the center and a low-speed zone at the edges, resulting in uneven flow field distribution. Simultaneously, excessive vertical velocity can easily cause powder to be blown away, affecting powder spreading stability and forming quality. Furthermore, while some existing equipment uses grid-guided structures, problems such as insufficient airflow stability and difficulty in timely removal of splashes still exist. Summary of the Invention

[0004] Based on the aforementioned shortcomings and deficiencies in the prior art, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the prior art. In other words, one of the objectives of this invention is to provide a 3D printer airflow field inlet rectifying device and its control method that meets one or more of the aforementioned requirements, thereby solving the problems of uneven airflow distribution, turbulence interference, and powder blowing in the prior art. By combining honeycomb and linear array dual rectifiers, uniform and stable airflow is achieved, improving cleaning efficiency, reducing oxidation, and enhancing the forming quality of printed parts.

[0005] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0006] An airflow field inlet rectification device for a 3D printer includes an air inlet split pipe, a honeycomb rectifier, and a linear array rectifier. The air inlet split pipe is split into two and connected to the air inlet ends of the honeycomb rectifier and the linear array rectifier, respectively. The air outlet ends of the honeycomb rectifier and the linear array rectifier are respectively sealed and connected to the printing chamber of the 3D printer. The air outlet end of the honeycomb rectifier is located above the air outlet end of the linear array rectifier.

[0007] As a preferred embodiment, the outlet end of the cellular rectifier is provided with a cellular channel array structure, and the cross-section of a single cellular channel is hexagonal.

[0008] As a preferred embodiment, the ratio of the axial length of the single-cell channel to the diameter of the inscribed circle of the hexagon is 6 to 10.

[0009] As a preferred embodiment, the outlet end of the linear array rectifier is provided with M horizontal grid plates and N vertical grid plates arranged in an array. Each vertical grid plate has N V-shaped guide grooves corresponding to the M horizontal grid plates. The horizontal grid plates are rotatably installed in the V-shaped guide grooves. The two ends of the horizontal grid plates are respectively installed on the side wall of the outlet end of the linear array rectifier through rotating shafts. The rotation of the horizontal grid plates is driven by a motor.

[0010] As a preferred embodiment, the V-shaped guide groove is used to limit the maximum deflection angle of one side of the transverse grid plate to ±θ°, where θ is 5 to 15°.

[0011] As a preferred embodiment, θ is 10.

[0012] As a preferred embodiment, the air inlet end of the linear array rectifier is equipped with an airflow velocity sensor, which is electrically connected to the controller.

[0013] The present invention also provides a control method for the airflow field inlet rectification device for 3D printers as described above. The controller generates a rotation angle command for the horizontal grid plate based on the inlet airflow velocity collected by the airflow velocity sensor and a preset speed-angle mapping relationship, so as to drive the corresponding motor to rotate the horizontal grid plate.

[0014] As a preferred embodiment, the control method includes: defining the inlet airflow velocity of the linear array rectifier as... The outlet airflow velocity of the linear array rectifier is The effective axial velocity of the export target is To ensure the maximum effective axial velocity of the outlet target for protective airflow. Actual axial effective speed at the outlet The current deflection angle of the horizontal grid is The maximum allowable deflection angle is The dead zone width of the target's effective axial velocity is The equivalent time constant of the motor drive is The angular velocity of the horizontal grid plate rotation is The upper limit of the angular velocity of the horizontal grid plate rotation is , The target axial proportion;

[0015] Target axial effective velocity at the exit: ;

[0016] in, ;

[0017] because ,so ;

[0018] ; For safety margin;

[0019] Feed angle for lateral grid plate rotation: ;

[0020] To suppress frequent actions caused by small perturbations, a dead zone and a smoothing gate function are introduced: Let Smoothing gate function ;in, ;in, for function;

[0021] make ;

[0022] Define direction coefficient for:

[0023] ;

[0024] Define command angle value for: ;

[0025] Then command angle for: ;

[0026] The constraints that the motor drive must satisfy are: ; .

[0027] As a preferred embodiment, the control method further includes:

[0028] The outlet airflow velocity Decompose into vertical velocity components and horizontal velocity : ;

[0029] Based on this, the axial attenuation relationship and performance indicators can be obtained: ;

[0030] When the deflection angle of the horizontal grid plate does not exceed the maximum allowable deflection angle control, the following conditions are met: ;

[0031] If the inlet airflow velocity is too high, the required deflection angle exceeds... The deflection angle is then executed. .

[0032] Compared with the prior art, the beneficial effects of this invention are as follows: The airflow field inlet rectifying device for 3D printers of this invention adopts a combined design of honeycomb rectifiers and linear array rectifiers. The honeycomb rectifier is used to forcibly divide the original turbulent high-speed flow into thousands of tiny channels, eliminating the central high-speed zone and the edge low-speed zone, so that the airflow distribution is uniform, forming a main protective laminar flow and suppressing air entrainment; the linear array rectifier is used to shape the airflow into multiple parallel and directional low-speed jets; the upper main protective laminar flow and the lower directional low-speed jets converge in the printing chamber to form a stable cooperative circulation field, achieving the dual goals of efficient dust removal and aerodynamic stability of the powder bed, and constructing an efficient and stable printing environment suitable for metal additive manufacturing; the control method of the airflow field inlet rectifying device for 3D printers of this invention can appropriately deflect the transverse grid plate according to the incoming flow velocity to control the longitudinal velocity of the airflow, preventing airflow turbulence and powder splashing in the printing chamber. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the airflow field inlet rectifier for a 3D printer installed in the printing chamber according to Embodiment 1 of the present invention;

[0034] Figure 2 This is a schematic diagram of the airflow field inlet rectifier device for a 3D printer according to Embodiment 1 of the present invention;

[0035] Figure 3 This is a schematic diagram of the linear array rectifier according to Embodiment 1 of the present invention;

[0036] Figure 4 This is a schematic diagram of the longitudinal grid plate of Embodiment 1 of the present invention;

[0037] Figure 5 This is a comparison diagram of the wind speed in the X direction of the airflow field inlet rectifier device of Embodiment 1 and Comparative Example 1 of the present invention;

[0038] Figure 6 This is a comparison diagram of the Z-direction wind speed of the airflow field inlet rectifier device in Embodiment 1 and Comparative Example 1 of the present invention. Detailed Implementation

[0039] To more clearly illustrate the embodiments of the present invention, specific implementation methods will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0040] Example 1:

[0041] like Figure 1 and Figure 2 As shown, the airflow field inlet rectifier for the 3D printer in this embodiment is installed on the printing chamber 4 to achieve the dual goals of efficient removal of smoke and dust in the printing chamber 4 and aerodynamic stability of the powder bed, thereby creating an efficient and stable printing environment suitable for metal additive manufacturing.

[0042] Specifically, the airflow field inlet rectifier for the 3D printer mentioned above includes a circular inlet splitter 1, a honeycomb rectifier 2, and a linear array rectifier 3;

[0043] The circular air intake splitter 1 is located on the outside of the printing chamber 4, and includes an upper pipe 11 and a lower pipe 12, which are connected to the honeycomb rectifier 2 and the linear array rectifier 3 respectively. It is used to introduce inert gas flow and divide the air flow into two channels to deliver it to the honeycomb rectifier 2 and the linear array rectifier 3.

[0044] Specifically, the air inlet end of the honeycomb rectifier 2 is connected to the upper pipe 11 of the circular air inlet splitter pipe 1 via a flange and sealing gasket. The air outlet end of the right end is sealed to the upper air inlet channel of the printing chamber 4 and fixed to the outer shell of the printing chamber via a snap-fit ​​structure to ensure assembly strength and sealing, thereby preventing the entrainment of external air. The right end of the honeycomb rectifier 2 has an internal honeycomb channel array structure. The cross-section of a single honeycomb channel is hexagonal, used to forcibly divide the original turbulent high-speed flow into thousands of tiny channels, eliminating the high-speed zone in the center and the low-speed zone at the edges, making the airflow distribution uniform and suppressing air entrainment. The ratio of the axial length of the aforementioned single honeycomb channel to the diameter of the inscribed circle of the hexagon is 6 (it can also be designed between 6 and 10 according to actual application requirements), a larger aspect ratio to enhance the rectification effect.

[0045] The air inlet end of the aforementioned linear array rectifier 3 is connected to the lower end pipe 12 of the circular air inlet splitter pipe 1 via a flange and sealing gasket. The air outlet end of the right end is sealed to the lower air inlet channel of the printing chamber 4 and fixed to the outer shell of the printing chamber via a snap-fit ​​structure to ensure assembly strength and sealing, thereby preventing the entrainment of external air. Figure 2 and Figure 3 As shown, the aforementioned linear array rectifier 3 includes a rectangular outer frame, and its outlet end is provided with three horizontal grid plates 31 and ten vertical grid plates 32 arranged in an array. The two grid plates intersect orthogonally within the outer frame and together form multiple rows of square flow channels; as shown Figure 4As shown, each longitudinal grid plate has a V-shaped guide groove 322 corresponding to the transverse grid plate, which is used to fit and connect with the transverse grid plate 31 and to guide and limit at the intersection; the transverse grid plate 31 is rotatably fitted with the V-shaped guide groove 322, and the two ends of the transverse grid plate 31 are respectively installed on the outlet side wall of the linear array rectifier through a rotating shaft, and the rotation of the transverse grid plate 31 is driven by the motor 5.

[0046] The deflection angle of the transverse grid plate 31 is limited to ±10° to avoid mutual interference and ensure the integrity of the channel cross section.

[0047] In this embodiment, the hexagonal side length of the cellular rectifier 2 is 2.9 mm, the wall thickness is 0.5 mm, and the inner length and width of the rectifier are 120 mm × 30 mm; the horizontal grid plate 31 of the linear array rectifier 3 has a total length of 110 mm, a width of 15 mm, and a thickness of 2 mm; the vertical grid plate 32 has a total length of 25 mm, a width of 15 mm, and a thickness of 1 mm.

[0048] In addition, an airflow velocity sensor is installed at the inlet side or upstream flow channel of the aforementioned linear array rectifier 3 and is electrically connected to the controller. Based on the incoming flow velocity obtained by the airflow velocity sensor, the controller generates a rotation angle command for the transverse grid plate 31 according to a preset velocity-angle mapping relationship, driving the corresponding motor 5 to adjust the deflection angle of the transverse grid plate. During operation, the transverse grid plate 31 deflects collaboratively within a range of ±10° (the angle is not limited to 10°, but can be determined between 5 and 15° according to actual application requirements), shaping the airflow from the pressure stabilizing chamber into a series of parallel, uniform, and directional low-speed jets. These controlled jets form an air cushion layer in the lower half of the printing chamber 4, maintaining momentum transfer along the printing direction (i.e., the X direction), reducing axial velocity attenuation, and significantly suppressing the vertical (i.e., Z direction) velocity component and the resulting powder scattering.

[0049] In this embodiment, when the airflow field inlet rectifier is working, the inert protective gas enters through the circular inlet splitter 1 and is divided into upper and lower paths. The upper airflow is rectified into a uniform and stable quasi-laminar flow by the hexagonal units of the honeycomb rectifier 2, and is uniformly fed into the upper part of the printing chamber 4 to form a main protective airflow covering the entire area and suppress the entrainment of external air, maintaining a low-oxygen environment in the molten pool area. The lower airflow enters the linear array rectifier 3. The airflow velocity on the inlet side is collected in real time by a sensor and sent to the controller. The controller generates a rotation command for the transverse grid plate 31 based on a preset speed and angle mapping, driving the end small motor 5 to make the transverse grid plate deflect around the axis under the guidance and limiting action of the V-shaped guide groove 322. The deflection amplitude is limited to ±10°, thereby ensuring the future... The lower airflow in the self-stabilizing chamber is shaped into multiple parallel and directional low-speed jets. These jets are introduced from the bottom of the printing chamber 4, creating a continuous near-wall air cushion layer on the powder bed surface. This provides momentum compensation along the printing direction and reduces axial velocity attenuation, while significantly weakening the vertical velocity component to suppress powder scattering and promote the directional migration of dust particles to the exhaust channel. When the incoming flow velocity exceeds the set operating range or the sensor malfunctions, the controller implements angle limiting or zeroing to maintain channel opening and sealing reliability. Finally, the upper main protective laminar flow and the lower directional low-speed jets converge in the printing chamber 4 to form a stable and coordinated circulating flow field, achieving the dual goals of efficient dust removal and aerodynamic stability of the powder bed, thus creating an efficient and stable printing environment suitable for metal additive manufacturing.

[0050] The specific control method of the airflow field inlet rectifier in this embodiment includes the following process:

[0051] Define the inlet airflow velocity of the linear array rectifier as The outlet airflow velocity of the linear array rectifier is The effective axial velocity of the export target is To ensure the maximum effective axial velocity of the outlet target for protective airflow. Actual axial effective speed at the outlet The current deflection angle of the horizontal grid is The maximum allowable deflection angle is The dead zone width of the target's effective axial velocity is The equivalent time constant of the motor drive is The angular velocity of the horizontal grid plate rotation is The upper limit of the angular velocity of the horizontal grid plate rotation is , The target axial proportion;

[0052] Target axial effective velocity at the exit: ;in, ;

[0053] because ,so ;

[0054] ;

[0055] For safety margin;

[0056] Feed angle for lateral grid plate rotation: ;

[0057] To suppress frequent actions caused by small perturbations, dead zones and smoothing gate functions are introduced:

[0058] make ;

[0059] when When the deviation is considered acceptable, no intervention is needed; once the dead zone is exceeded, Smoothly amplify the control value within [0,1];

[0060] Smooth gate function ;in, ;in, for function;

[0061] make ;

[0062] Define direction coefficient for:

[0063] ;

[0064] Define command angle value for:

[0065] ;

[0066] Then command angle for:

[0067] ;

[0068] The constraints that the motor drive must satisfy are:

[0069] ; ;

[0070] To ensure that the angle change is smooth and does not exceed the mechanical limit; the above control method can be applied to the transverse grid plate to achieve the deflection angle adjustment under the guidance and limiting cooperation of the guide groove.

[0071] In addition, the aforementioned outlet airflow velocity Decompose into vertical velocity components and horizontal velocity :

[0072] ;

[0073] Based on this, the axial attenuation relationship and performance indicators can be obtained:

[0074] ;

[0075] When the deflection angle of the horizontal grid plate does not exceed the maximum allowable deflection angle control, the following conditions are met:

[0076] ;

[0077] If the inlet airflow velocity is too high, the required deflection angle exceeds... The deflection angle is then executed. This is to ensure channel opening and rectification stability.

[0078] Comparative Example 1:

[0079] The difference between the airflow field inlet rectifying device for the 3D printer in this embodiment and that in embodiment 1 is:

[0080] The horizontal grid plate is fixed and cannot be deflected; the horizontal grid plate and the vertical grid plate are perpendicular to each other; other structures are the same as in Example 1.

[0081] The following comparative tests are conducted on the airflow field inlet rectifier devices of Example 1 and Comparative Example 1, such as... Figure 5 As shown, the initial airflow velocity of both schemes is 3 m / s. In the X direction (i.e., the printing direction), after traveling 200 mm along the airflow path, the airflow velocity using Embodiment 1 of the present invention decreases to approximately 2.35 m / s, while the airflow velocity using Comparative Example 1 decreases significantly to approximately 0.25 m / s. Figure 6 As shown, in the Z direction (i.e., the direction perpendicular to the printing plane), the control method of Example 1 can effectively control the airflow velocity in this direction to below 0.2 m / s throughout the entire test distance; in contrast, the airflow velocity in the Z direction of Comparative Example 1 continuously increases with the distance, and its maximum value exceeds 1.3 m / s.

[0082] In summary, this invention can ensure a high flow rate in the printing direction (X direction) to effectively remove processing fumes while strictly suppressing the flow rate in the vertical direction (Z direction), thereby effectively avoiding disturbance of the powder bed by high-speed airflow and ultimately achieving high stability and high yield in the printing process.

[0083] The above description is merely a detailed explanation of preferred embodiments and principles of the present invention. For those skilled in the art, there may be changes in specific implementation methods based on the ideas provided by the present invention, and these changes should also be considered within the scope of protection of the present invention.

Claims

1. An airflow field inlet rectifying device for a 3D printer, characterized in that, It includes an air intake splitter, a honeycomb rectifier, and a linear array rectifier. The air intake splitter splits into two parts and connects to the air intake ends of the honeycomb rectifier and the linear array rectifier respectively. The air outlet ends of the honeycomb rectifier and the linear array rectifier are respectively sealed and connected to the printing chamber of the 3D printer. The air outlet end of the honeycomb rectifier is located above the air outlet end of the linear array rectifier. The outlet end of the cellular rectifier is provided with a cellular channel array structure, and the cross-section of a single cellular channel is hexagonal; The ratio of the axial length of the single-cell channel to the diameter of the inscribed circle of the hexagon is 6 to 10. The outlet end of the linear array rectifier is provided with M horizontal grid plates and N vertical grid plates arranged in an array. Each vertical grid plate has N V-shaped guide grooves that correspond one-to-one with the M horizontal grid plates. The horizontal grid plates are rotatably installed in the V-shaped guide grooves. The two ends of the horizontal grid plates are respectively installed on the side wall of the outlet end of the linear array rectifier through rotating shafts. The rotation of the horizontal grid plates is driven by a motor. The V-shaped guide groove is used to limit the maximum deflection angle of one side of the transverse grid plate to ±θ°, where θ is 5 to 15°. The linear array rectifier is equipped with an airflow velocity sensor at its inlet end, and the airflow velocity sensor is electrically connected to the controller.

2. The airflow field inlet rectifying device for a 3D printer according to claim 1, characterized in that, The value of θ is 10.

3. The control method for the airflow field inlet rectifying device for a 3D printer as described in claim 1, characterized in that, The controller generates a rotation command for the horizontal grid plate based on the inlet airflow velocity collected by the airflow velocity sensor and a preset speed-angle mapping relationship, so as to drive the corresponding motor to rotate the horizontal grid plate.

4. The control method according to claim 3, characterized in that, include: Define the inlet airflow velocity of the linear array rectifier as The outlet airflow velocity of the linear array rectifier is The effective axial velocity of the export target is To ensure the maximum effective axial velocity of the outlet target for protective airflow. Actual axial effective speed at the outlet The current deflection angle of the horizontal grid is The maximum allowable deflection angle is The dead zone width of the target's effective axial velocity is The equivalent time constant of the motor drive is The angular velocity of the horizontal grid plate rotation is The upper limit of the angular velocity of the horizontal grid plate rotation is , The target axial proportion; Target axial effective velocity at the exit: ;in, ; because ,so ; ； For safety margin; Feed angle for lateral grid plate rotation: ; To suppress frequent actions caused by small perturbations, dead zones and smoothing gate functions are introduced: make ; Smooth gate function ;in, ;in, for function; make ; Define direction coefficient for: ； Define command angle value for: ； Then command angle for: ； The constraints that the motor drive must satisfy are: ； 。 5. The control method according to claim 4, characterized in that, Also includes: The outlet airflow velocity Decompose into vertical velocity components and horizontal velocity : ； Based on this, the axial attenuation relationship and performance indicators can be obtained: ； When the deflection angle of the horizontal grid plate does not exceed the maximum allowable deflection angle control, the following conditions are met: ； If the inlet airflow velocity is too high, the required deflection angle exceeds... The deflection angle is then executed. .

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