Air inlet channel structure suitable for metal 3d printing equipment

Abstract

The invention discloses an air inlet channel structure suitable for metal 3d printing equipment. The air inlet channel structure comprises an inlet section, a snakelike mixing pipe section and a rectification section which are sequentially connected in series in the airflow direction. Wherein the snakelike mixing pipe section consists of a section of pipeline which is bent for multiple times, and the bending frequency is not less than three times. Preferably, a primary rectification part and a secondary rectification part are sequentially arranged in the rectification section in the airflow direction. The snakelike mixing pipe section promotes air flow to generate violent transverse momentum exchange and mixing in the section of the pipeline through the Dean vortex effect, so that the air flow from an inlet is effectively homogenized, and large-scale turbulence pulsation is preliminarily weakened. And then the airflow enters the rectifying section and is converted into a laminar flow or quasi-laminar flow air field which is perpendicular to the air outlet surface (the air outlet surface is the outlet end section of the rectifying section), flows stably and is uniform in thickness through the rectifying section.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology. Specifically, it relates to the air field control technology of selective laser melting (SLM) forming equipment, the optimization of the uniformity of air field speed in the forming chamber, and especially to an air inlet structure suitable for metal 3D printing equipment. Background Technology

[0002] With the large-scale application of laser selective melting technology in high-end manufacturing fields such as aerospace and medical implants, the impact of metal vapor, fumes, and molten spatter generated by high-energy lasers on the forming quality is becoming increasingly prominent. Specifically, this includes issues such as residual black smoke, uncontrolled spatter behavior, and lack of uniformity in the airflow field.

[0003] Black smoke residue problem: Black smoke formed by the condensation of metal vapor will be deposited on the surface of the laser lens, resulting in decreased optical transmittance and lens corrosion. At the same time, some black smoke and spatter fall back into the powder bed, forming defects such as pores and inclusions during the solidification process of the molten pool, which significantly reduces the density and fatigue life of the molded parts.

[0004] Uncontrolled spatter behavior: Unstable jets of molten metal from the molten pool fall randomly into unmelted powder layers or formed areas under the guidance of undirected airflow, causing interlayer incompatibility, spheroidization defects, and deterioration of surface roughness.

[0005] Problem of wind field uniformity: If the standard deviation of wind speed distribution uniformity is too large, it will lead to insufficient airflow speed in some areas of the forming zone, which will not be able to effectively remove smoke and dust; while the high-speed zone will disturb the stability of the molten pool and aggravate splashing. Summary of the Invention

[0006] The purpose of this invention is to provide an air intake structure suitable for metal 3D printing equipment, so as to solve the molding defect problem caused by insufficient air velocity uniformity in large-format SLM equipment in the prior art.

[0007] The technical solution of this invention is as follows: An air intake structure suitable for metal 3D printing equipment includes an inlet section, a serpentine mixing pipe section, and a rectifier section connected in series along the airflow direction; the serpentine mixing pipe section is composed of a pipe with multiple bends, and the number of bends is no less than three.

[0008] In a preferred embodiment of the air intake structure for metal 3D printing equipment, the serpentine hybrid pipe section is composed of a pipe exhibiting a continuous S-shaped bend.

[0009] In a preferred embodiment of the air intake structure for metal 3D printing equipment, the bending radius of the pipe in the serpentine hybrid pipe section is 10-50 mm.

[0010] In a preferred embodiment of the air intake structure for metal 3D printing equipment, a quick-connect fitting is provided at the inlet end of the inlet section.

[0011] In a preferred embodiment of the air intake structure for a metal 3D printing device, the inlet section includes a circular pipe section and a variable section. The inlet end of the circular pipe section is the inlet end of the inlet section, the outlet end of the circular pipe section is connected to the inlet end of the variable section, and the outlet end of the variable section is connected to the inlet end of the serpentine mixing pipe section.

[0012] In a preferred embodiment of the air intake structure for a metal 3D printing equipment, a primary rectification section and a secondary rectification section are sequentially arranged along the airflow direction within the rectification section, and the primary rectification section and the secondary rectification section are separated by a certain distance along the airflow direction; The preliminary rectifier is configured to depressurize the passing airflow.

[0013] In a preferred embodiment of the air intake structure for a metal 3D printing equipment, the preliminary rectifier includes a first-stage grid. The aperture of the primary grid is 2 to 4 mm, and / or the porosity of the primary grid is 10% to 30%.

[0014] In a preferred embodiment of the air intake structure for metal 3D printing equipment, the secondary rectifier includes a two-stage grid. The aperture of the secondary grid is 4 to 6 mm, and / or the porosity of the secondary grid is 30% to 70%.

[0015] In a preferred embodiment of the air intake structure for a metal 3D printing equipment, the preliminary rectifier includes a primary grid, and the length of the holes in the secondary grid is 2 to 4 times the length of the holes in the primary grid.

[0016] In a preferred embodiment of the air intake structure for a metal 3D printing device, the distance between the primary rectifier and the secondary rectifier along the airflow direction is 40-60 mm.

[0017] Because the present invention adopts the above technical solution, it has the following advantages and positive effects compared with the prior art: The air intake structure for metal 3D printing equipment provided by this invention utilizes the Dean vortex effect to induce intense lateral momentum exchange and mixing of the airflow within the pipe cross-section, effectively homogenizing the airflow from the inlet and initially weakening large-scale turbulent fluctuations. The airflow then enters the rectifying section, where it is transformed into a stable, uniform laminar or quasi-laminar flow field perpendicular to the outlet surface (which is the outlet end cross-section of the rectifying section).

[0018] Therefore, by adopting the air intake structure for metal 3D printing equipment provided by this invention, the standard deviation of wind speed uniformity on the working plane of the molding chamber can be significantly improved (i.e., high wind speed uniformity); the output airflow turbulence intensity is low, forming a true laminar airflow layer, effectively avoiding disturbance to the molten pool (i.e., excellent flow quality); thanks to the uniform and stable air field, splashing and dust during the molding process are effectively controlled, and the porosity of the molded parts can be stably controlled below 0.05%, with a density exceeding 99.95% (significantly improved molding quality). Attached Figure Description

[0019] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention.

[0020] Figure 1 This is a schematic diagram of an air intake structure suitable for metal 3D printing equipment according to the present invention; Figure 2 This is a schematic diagram of an entry section according to the present invention; Figure 3 This is a schematic diagram of a serpentine hybrid pipe section according to the present invention; Figure 4 This is a schematic diagram of a primary grid plate according to the present invention; Figure 5 This is a schematic diagram of a secondary grid plate according to the present invention.

[0021] Explanation of reference numerals in the attached figures: 1: Inlet section; 11: Circular pipe section; 12: Variation section; 2: Serpentine mixing pipe section; 3: Rectifying section; 31: Rectangular channel; 32: Primary grid plate; 33: Secondary grid plate. Detailed Implementation

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention 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.

[0023] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of components with the same structure or function is shown schematically, or only one is labeled. In this document, "one" can mean not only "only one" but also "more than one".

[0024] In the description of this invention, the term "a" not only means "only one" but can also mean "more than one". The terms "first", "second", "third", etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. The terms "perpendicular" and "parallel" do not mean absolutely perpendicular or parallel, but can be approximately perpendicular or approximately parallel.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0026] See Figures 1 to 5 This embodiment provides an air intake structure suitable for metal 3D printing equipment, including an inlet section 1, a serpentine mixing pipe section 2, and a rectifier section 3 connected in series along the airflow direction. The serpentine mixing pipe section 2 is composed of a pipe with multiple bends, and the number of bends is no less than three. Preferably, the rectifier section 3 has a preliminary rectifier and a secondary rectifier sequentially arranged along the airflow direction.

[0027] The serpentine mixing section 2, through the Dean vortex effect, induces intense lateral momentum exchange and mixing of the airflow within the pipe cross-section, thereby effectively homogenizing the airflow from the inlet and initially weakening large-scale turbulent fluctuations. The airflow then enters the rectifying section 3, where it is transformed into a laminar or quasi-laminar flow field that is perpendicular to the outlet surface (the outlet surface is the outlet end cross-section of the rectifying section 3), with stable flow and uniform thickness.

[0028] The following is a further description of the air intake structure applicable to metal 3D printing equipment in this embodiment.

[0029] like Figure 1 As shown in the figure, the air intake structure for metal 3D printing equipment provided in this embodiment is connected in series along the airflow direction (as indicated by the arrow in the figure), and mainly includes: inlet section 1, serpentine mixing pipe section 2, and rectangular channel 31. The rectangular channel 31 is provided with a primary rectification section and a secondary rectification section. The components (inlet section 1, serpentine mixing pipe section 2, and rectangular channel 31) are connected in an airtight manner by flanges or welding, together forming a complete rectification path from airflow input to high-quality laminar flow wind field output.

[0030] like Figure 1 and Figure 2 As shown, inlet section 1 is located at the beginning of the entire air intake structure and is used to introduce inert gases (such as argon or nitrogen). Inlet section 1 includes a circular pipe section 11 and a transition section 12. The inlet end of the circular pipe section 11 is the inlet end of inlet section 1, and the outlet end of the circular pipe section 11 is connected to the inlet end of the transition section 12. The outlet end of the transition section 12 is connected to the inlet end of the serpentine mixing pipe section 2. Furthermore, the circular pipe section 11 adopts a standard circular diameter, and the inlet end of the pipe section is equipped with a quick-connect fitting to facilitate quick and reliable connection with an external inert gas source, ensuring airtightness. As the input end of the airflow, the size of inlet section 1 can be designed according to the overall flow requirements of the equipment.

[0031] like Figure 1 and Figure 3 As shown, the outlet end of the transition section 12 is connected to the inlet end of the serpentine mixing section 2. The serpentine mixing section 2 consists of a pipe with continuous S-shaped bends, with at least three bends, and the bend radius is preferably between 10mm and 50mm. The design of the serpentine mixing section 2 aims to utilize the Dean vortex effect to induce intense lateral momentum exchange and mixing of the airflow within the pipe cross-section, thereby effectively homogenizing the airflow from the inlet and initially weakening large-scale turbulent fluctuations. Key parameters of this design, such as the bend radius and the number of bends, directly affect the airflow mixing effect. Generally, the optimal bend radius range is 10mm to 50mm, and it should be adapted according to the flow requirements of the equipment.

[0032] The rectifier section includes a rectangular channel 31 and a primary rectifier section and a secondary rectifier section disposed within the rectangular channel 31.

[0033] like Figure 1 and Figure 4As shown, the outlet side of the serpentine mixing section 2 is connected to a rectangular channel 31. Inside the rectangular channel 31, a preliminary rectification section is first arranged along the airflow direction. This preliminary rectification section is configured to reduce the pressure of the passing airflow. Specifically, the preliminary rectification section includes a primary grid, more specifically, a primary grid plate 32. The primary grid plate 32 is a circular perforated plate with a certain thickness and small pore size (e.g., 3 mm), with a recommended pore size range of 2 mm to 4 mm and a porosity preferably of 10% to 30%. The core function of the primary grid is to apply a significant local pressure drop to the airflow that has undergone preliminary mixing in the serpentine mixing section 2. This pressure drop process can further homogenize the airflow pressure, break up the remaining medium-scale vortices, and achieve "preliminary rectification" of the airflow, adjusting the airflow to a state with a more consistent direction, although slight disturbances may still exist.

[0034] like Figure 1 and Figure 5 As shown, inside the rectangular channel 31, downstream of the primary rectification section and at a certain distance L (i.e., the primary and secondary rectification sections are separated by a certain distance L along the airflow direction), a secondary rectification section is provided. Specifically, the secondary rectification section includes a secondary grid, more specifically a secondary grid plate 33. The secondary grid plate 33 is a circular perforated plate with relatively large pores, the pore diameter of which is larger than that of the primary grid (e.g., 5 mm), with a recommended pore diameter range of 4 mm to 6 mm and a porosity of 30% to 70%. The certain distance L provides space for the airflow to readjust and develop after primary rectification. The core function of the secondary grid is "laminarization". The larger but uniformly sized channels on the secondary grid plate 33, like multiple parallel micro-ducts, can effectively guide the airflow direction, suppress its lateral pulsation, and ultimately transform the already homogenized airflow from the primary grid into a laminar or quasi-laminar airflow field perpendicular to the outlet surface, with stable flow and uniform thickness. The preferred spacing L is 40mm to 60mm, and the specific value can be adjusted according to the rectification effect. The length of the holes in the secondary grid is preferably 2 to 4 times the length of the holes in the primary grid.

[0035] The air intake structure for metal 3D printing equipment provided in this embodiment allows inert gas to enter from inlet section 1 during operation. It first flows through serpentine mixing section 2, where the S-shaped bend induces a powerful Dean vortex to mix the airflow, achieving initial homogenization. Subsequently, the airflow enters rectangular channel 31, penetrating the primary and secondary grids sequentially. The primary grid mainly provides pressure drop and coarse rectification, responsible for "straightening" the airflow. The secondary grid mainly guides and refines the airflow, responsible for "smoothing" it into laminar flow. A certain distance L between the primary and secondary grids is an important parameter, ensuring sufficient relaxation space for the airflow after primary rectification and preventing flow field interference caused by excessively close distance between the primary and secondary grids, thus ensuring the final effect of secondary rectification.

[0036] The air intake structure for metal 3D printing equipment provided in this embodiment, through the synergistic effect of the aforementioned "bending mixing + two-stage gradient rectification," can generate a highly uniform and stable laminar flow field from the source. After this air field is sent into the forming chamber of the SLM equipment, it can: ① effectively remove smoke and splatter generated by the laser molten pool at a uniform wind speed, preventing them from depositing on optical lenses or contaminating the powder bed; ② the stable laminar flow can avoid unnecessary disturbance to the molten pool, thereby improving the stability of the molten pool; ③ ultimately significantly improve the density of the formed parts, stably control the porosity at an extremely low level (e.g., below 0.05%), and improve the mechanical properties and surface quality of the parts.

[0037] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they shall still fall within the protection scope of the present invention.

Claims

1. An air intake structure suitable for metal 3D printing equipment, characterized in that, It includes an inlet section, a serpentine mixing pipe section, and a rectifier section connected in series along the airflow direction; the serpentine mixing pipe section is composed of a pipe with multiple bends, and the number of bends is no less than three.

2. The air intake structure for metal 3D printing equipment according to claim 1, characterized in that, The serpentine hybrid pipe section consists of a section of pipe with a continuous S-shaped bend.

3. The air intake structure for metal 3D printing equipment according to claim 1, characterized in that, The bending radius of the pipe in the serpentine hybrid pipe section is 10 to 50 mm.

4. The air intake structure for metal 3D printing equipment according to claim 1, characterized in that, The inlet end of the inlet section is equipped with a quick-connect fitting.

5. The air intake structure for metal 3D printing equipment according to claim 1, characterized in that, The inlet section includes a circular pipe section and a transition section. The inlet end of the circular pipe section is the inlet end of the inlet section. The outlet end of the circular pipe section is connected to the inlet end of the transition section. The outlet end of the transition section is connected to the inlet end of the serpentine mixing pipe section.

6. The air intake structure for metal 3D printing equipment according to claim 1, characterized in that, The rectification section is provided with a preliminary rectification section and a secondary rectification section in sequence along the airflow direction, and the preliminary rectification section and the secondary rectification section are separated by a certain distance along the airflow direction; The preliminary rectifier is configured to depressurize the passing airflow.

7. The air intake structure for metal 3D printing equipment according to claim 6, characterized in that, The preliminary rectifier section includes a first-stage grid; The aperture of the primary grid is 2 to 4 mm, and / or the porosity of the primary grid is 10% to 30%.

8. The air inlet structure for metal 3D printing equipment according to claim 6, characterized in that, The secondary rectifier section includes a two-stage grid; The aperture of the secondary grid is 4 to 6 mm, and / or the porosity of the secondary grid is 30% to 70%.

9. The air inlet structure for metal 3D printing equipment according to claim 8, characterized in that, The primary rectifier section includes a primary grid, and the length of the holes in the secondary grid is 2 to 4 times the length of the holes in the primary grid.

10. The air intake structure for metal 3D printing equipment according to claim 6, characterized in that, The distance between the primary rectifier and the secondary rectifier along the airflow direction is 40 to 60 millimeters.

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