Lens protection airflow forming device

Abstract

The utility model belongs to the field of additive manufacturing, and relates to a lens protection airflow forming device which comprises at least two sets of top air blowing openings and air suction openings which are formed in a forming chamber. Conveying at least two paths of lens protection airflow sweeping the lower surface of the optical system protection lens into the forming chamber through a top air blowing opening; the top air blowing opening is communicated with the air suction opening through lens protection airflow. The utility model provides the lens protection air flow forming device capable of effectively maintaining the cleanness of the surface of the lens of an optical system for a long time, and on the basis, the combination of lens protection and powder bed protection of additive manufacturing equipment can be realized through the lens protection air top partition plate placed in the middle of the top of the forming chamber; and a wind field scheme capable of effectively reducing the slag falling amount of the breadth, obviously improving the part forming quality and protecting the lens is formed.

Description

Technical Field

[0001] The utility model belongs to the field of additive manufacturing, and relates to a forming device for a protective air flow, in particular to a forming device for a protective air flow of a lens. Background Art

[0002] With the continuous development of additive manufacturing technology, the mainstream development direction of selective laser melting (SLM) equipment presents the characteristics of large format, multi-beam, and strong robustness, so as to achieve the goals of producing larger-sized parts, higher printing efficiency, and longer stable working hours of the equipment. The protective atmosphere circulation filtration system is an indispensable part of traditional SLM equipment. Since by-products such as metal vapor and metal droplet splashes are generated during the melting process of high-power laser on the metal powder bed, they all need to be taken away in time to avoid floating and secondary deposition from affecting the working state of the equipment. Metal dust or splashes during the sintering process will flow in the forming chamber along with the inert protective atmosphere. Part of them will be directly sucked into the circulation filtration system by the suction port, while the other part of the lighter dust will move inside the forming chamber along with the flow field. When it moves to the protective mirror along with the flow field, it will adsorb on the protective lens. After a certain period of accumulation, it will cause blockage in the path of the laser, reducing the energy density of the laser incident on the powder bed and resulting in poor sintering. To ensure the printing quality, it is necessary to form an energy source lens protection gas film to cover the surface of the optical lens for a long time and stably to isolate by-products such as metal dust. Currently, there are two main ways to protect the lens of the equipment: the wind wall type lens protection and the direct blowing type lens protection of the protective mirror. Among them, the wind wall type lens protection method is to generate a protective atmosphere flow field with a single overall velocity vector direction in the working cavity, so as to take away the dust with a uniform flow field. However, this method has a high air volume requirement for the equipment, which will increase the load of the filtration system fan. More importantly, the difficulty of uniformity control is relatively high. In equipment with a large forming area span, the flow field of the wind wall type and direct blowing type lens protection has a long travel distance. The overall velocity of the protective flow field is low in the middle section, and the lens protection effect rapidly weakens. There are certain defects in the protection effect. Moreover, the turbulence intensity of the flow field at the starting section of the multi-hole jet of the wind wall is relatively high, and the protective gas is easy to adhere to metal dust when it first enters the working cavity of the forming chamber, and the protection effect near the optical lens is limited. The direct blowing type lens protection gas of the protective mirror can form a high-flow-rate thin-layer thick gas film covering layer on the lower surface of the optical lens. However, due to the very large consumption of inert gas by the high-flow-rate lens protection air flow, the equipment usage cost will be increased. Summary of the Utility Model

[0003] In order to solve the above technical problems in the background art, the utility model provides a lens protection air flow forming device that can effectively improve the lens cleaning effect of a large-format additive manufacturing device.

[0004] To achieve the above object, the utility model adopts the following technical solutions:

[0005] A lens protection air flow forming device, characterized in that: the lens protection air flow forming device includes at least two groups of top air outlets and air inlets arranged inside the forming chamber; at least two paths of lens protection air flows that sweep across the lower surface of the optical system protection mirror are conveyed into the forming chamber through the top air outlets; the top air outlets are communicated with the air inlets through the lens protection air flows.

[0006] The above two groups of top air outlets and air inlets are arranged at intervals in the top area of the forming chamber.

[0007] The above two top air outlets are respectively arranged at the tops of the opposite side walls of the forming chamber; the air inlets include a first air inlet and a second air inlet; the first air inlet and the second air inlet are arranged in the middle area at the top of the forming chamber; the two top air outlets are respectively communicated with the first air inlet and the second air inlet through the lens protection air flows. The above two top air outlets are arranged at the middle position at the top of the forming chamber; the air inlets include a first air inlet and a second air inlet; the first air inlet and the second air inlet are respectively arranged on the side walls of the forming chamber opposite to the two top air outlets.

[0008] The above lens protection air flow forming device further includes a lens protection air top partition plate arranged at the middle position at the top of the forming chamber; the two top air outlets are respectively arranged at the tops of the opposite side walls of the forming chamber; the air inlets include a first air inlet and a second air inlet located at the bottom of the side wall of the forming chamber; the first air inlet and the second air inlet are respectively arranged on the opposite side walls of the forming chamber; the same group of top air outlets and air inlets are arranged on the same side wall of the forming chamber; the lens protection air flows blown out in opposite directions by the two top air outlets are respectively communicated with the first air inlet and the second air inlet after being separated and guided by the lens protection air top partition plate.

[0009] The above lens protection air top partition plate includes a web and wing plates arranged on the web; the cross-section of the lens protection air top partition plate is integrally in a T shape; the wing plates are connected to the top of the forming chamber; the two paths of lens protection air flows are respectively guided by the web of the lens protection air top partition plate and flow from the top of the forming chamber to the forming width and then flow from the center of the forming width to both sides of the forming width.

[0010] The above lens protection air top partition plate further includes a flow guide plate arranged between the wing plates and the web and respectively connected to the wing plates and the web; the flow guide plate is an arc-shaped flow guide plate or an inclined plane flow guide plate; the two paths of lens protection air flows are respectively guided by the flow guide plate and flow from the top of the forming chamber to the forming width and then flow from the center of the forming width to both sides of the forming width.

[0011] The above-mentioned lens protection air flow forming device includes a suction duct, a filtration system, and a fan; the suction port is connected to the filtration system through the suction duct; the filtration system is connected to the top air outlet through the fan; the fan is connected to two top air outlets respectively through a flow dividing device; the flow dividing device is a pipeline flow divider with adjustable flow rate.

[0012] The above-mentioned lens protection air flow forming device further includes a top air outlet extension section; the top air outlet extension section is connected to the top air outlet; the top air outlet extension section is of a semi-extension structure or a full-extension structure; the thickness of the top air outlet extension section is H, and the H is not less than 20 mm.

[0013] When the above-mentioned top air outlet extension section is of a semi-extension structure, the shortest distance between the top air outlet extension section and the optical system protection mirror is D, and the D is not greater than 300 mm;

[0014] When the above-mentioned top air outlet extension section is of a full-extension structure, the top air outlet extension section covers the optical system protection mirror, and through holes are provided at the projection position of the optical system protection mirror on the top air outlet extension section along the top air outlet extension section; the diameter of the optical system protection mirror is φ 镜 ; the aperture of the through hole is φ 孔 , the φ 孔 ≥φ 镜 .

[0015] The above-mentioned lens protection air flow forming device further includes a lens protection air extension baffle extending from the top of the forming chamber to the forming surface; the axis where the lens protection air extension baffle is located is parallel to the flow direction of the lens protection air flow; the height of the lens protection air extension baffle is L, and the L is not less than 1.2H; the distance between the lens protection air extension baffle and the top air outlet extension section is Y; the Y is not greater than 30 mm.

[0016] The advantages of the present utility model are:

[0017] The present utility model provides a lens protection air flow forming device, including at least two groups of top air outlets and a suction port arranged inside the forming chamber; the wind directions of the two top air outlets are opposite; at least two paths of lens protection air flows that sweep across the lower surface of the optical system protection mirror are delivered into the forming chamber through the top air outlets. By setting at least two paths of lens protection air flows, the lens protection area is divided, and a lens protection flow field with a certain thickness is formed under the protection lens by arranging the top air outlet extension section in the forming chamber, or the two are combined, so as to suppress the backflow of the metal dust entrained in the working cavity and effectively avoid the dust adhering to the protection lens and causing pollution. The present utility model constructs a long-lasting and effective air film covering layer under the optical system protection mirror, and improves the stability of the optical system of the super-large SLM device during long-term operation. Brief Description of the Drawings

[0018] Figure 1 Schematic structural diagram of the lens protection air flow forming device provided by the present utility model;

[0019] Figure 2 Schematic structural diagrams of two different forms of top partitions of the lens protection air provided by the present utility model;

[0020] Figure 3 Schematic structural diagram of the extended air outlet of the left and right side blowing additive manufacturing equipment and the air flow field structure of the lens protection air space;

[0021] Figure 4 Schematic structural diagram of the lens protection air flow forming device (top facing suction) provided by the present utility model;

[0022] Figure 5 Schematic structural diagram of the lens protection air flow forming device (top back suction) provided by the present utility model;

[0023] Figure 6 Schematic structural diagram of the lens protection air flow forming device (top same - direction suction) provided by the present utility model;

[0024] Wherein:

[0025] 1 - forming chamber; 2 - optical system; 3 - powder bed; 4 - first air suction port; 5 - second air suction port; 6 - air suction pipeline; 7 - filtration system; 8 - fan; 9 - shunt tee; 14 - top air blowing port; 15 - extended section of the top air blowing port; 16 - upper surface of the working cavity; 17 - extended baffle of the lens protection air; 18 - top partition of the lens protection air; 19 - lens protection air shunt device. Detailed Embodiments

[0026] The present utility model provides a lens protection air flow forming device, which includes a top air blowing port 14 and an air suction port arranged inside the forming chamber 1; there are two top air blowing ports 14, and the two top air blowing ports 14 are arranged at intervals facing each other, or back to back, or in the same direction; the lens protection air flow that sweeps across the lower surface of the optical system is conveyed into the forming chamber 1 through the top air blowing port 14; the top air blowing port 14 is communicated with the air suction port through the lens protection air flow. The air suction port includes a first air suction port 4 and a second air suction port 5; the two air suction ports are basically at the same height as the two top air blowing ports 14, or the height where the two air suction ports are located is significantly lower than the height where the two top air blowing ports 14 are located.

[0027] When the two air suction ports are basically at the same height as the two top air blowing ports 14, the two air suction ports are respectively opposite to the two top air blowing ports 14, such as Figure 4 , Figure 5 and Figure 6As shown in the figure. Among them, Figure 4 two top air inlets 14 on the side wall of the forming chamber blow lens protection airflows towards two air outlets in the middle position of the forming chamber, that is, the two top air inlets 14 are arranged opposite to each other. Figure 5 two top air inlets 14 in the middle position of the forming chamber blow lens protection airflows towards two air outlets on the side wall of the forming chamber, that is, the two top air inlets 14 are arranged back to back. Figure 6 two groups of air inlets and air outlets are arranged at intervals in the top area of the forming chamber, that is, the two top air inlets 14 are arranged at intervals in the same direction.

[0028] When the heights of the two air outlets are significantly lower than the heights of the two top air inlets 14, the structure is as Figure 1 shown. At this time, the lens protection airflow forming device further includes a lens protection air top partition 18 placed at the middle position of the top of the forming chamber 1; the two top air inlets 14 are symmetrically arranged on the side wall of the forming chamber 1 along the axis where the lens protection air top partition 18 is located; the lens protection airflow includes two paths of lens protection airflows with opposite flow directions; the two paths of lens protection airflows are guided by the lens protection air top partition 18 and flow from the top of the forming chamber 1 to the forming width and then flow along the center of the forming width to both sides of the forming width; along the flow direction of the protection airflow on the forming width, the first air outlet 4 and the second air outlet 5 are arranged opposite to each other and are located at both sides of the forming width. In order to further reduce the turbulence intensity in the convection impact area of the left and right lens protection airflows in the central area of the optical top plate, a lens protection air top partition 18 is installed at the top of the equipment working cavity. By using a solid wall surface to separate the left and right lens protection air domains at the central cross-section position of the equipment and guiding the lens protection air to diffuse downward with the main flow area of the top blowing and flow to the center of the powder bed along with the main flow area. Refer to Figure 2 , the lens protection air top partition 18 adopted by the present utility model includes a web plate and wing plates arranged on the web plate; the cross-section of the lens protection air top partition 18 is integrally in a T shape; the wing plates are connected to the top of the forming chamber 1; the two paths of lens protection airflows flow from the top of the forming chamber 1 to the forming width and then flow along the center of the forming width to both sides of the forming width after being guided by the web plate of the lens protection air top partition 18. In order to reduce the turbulence intensity of the two sides of the lens protection airflows when flowing to the lens protection gas top partition, as Figure 2 shown, the lens protection air top partition 18 eliminates the eddy current area where the lens protection air contacts the solid wall surface through an arc side structure (or a flat inclined surface structure), effectively reducing the consistency of the flow rate distribution in the front and back directions in the working cavity, that is, the X direction in the figure, while realizing the deflection of the air flow velocity direction. That is, the lens protection air top partition 18 further includes a guide plate placed between the wing plates and the web plate; the guide plate is an arc guide plate or an inclined surface guide plate; the two paths of lens protection airflows are guided by the guide plate.

[0029] The lens protection air flow forming device further includes a top air outlet extension section 15 that extends from the end of the top air outlet 14 along the axis of the top air outlet 14 into the interior of the forming chamber 1; the axis where the top air outlet extension section 15 is located is parallel to the plane where the top of the forming chamber 1 is located; the top air outlet extension section 15 is a semi-extension structure or a full-extension structure; the thickness of the top air outlet extension section 15 is H, and H is not less than 20 mm. After the left and right side lens protection gases pass through the lens protection gas flow splitting device 14 and the top air outlet extension section 15, a uniform gas film covering layer is formed under the optical lens. After being restricted by the lens protection gas top partition 18 in the central area, the lens protection gas adjusts its direction and deflects downward, converges with the top blowing main flow area and flows to the powder bed surface. That is, the blowing device further includes a top air outlet extension section 15 that extends from the end of the top air outlet 14 to the lens protection gas top partition 18; the axis where the top air outlet extension section 15 is located is parallel to the plane where the top of the forming chamber 1 is located; the top air outlet extension section 15 is a semi-extension structure or a full-extension structure; the thickness of the top air outlet extension section 15 is H, and H is not less than 20 mm, so as to ensure that the lens protection gas film has a sufficient thickness to effectively cover the surface of the protection lens of the optical system 2. When the top air outlet extension section 15 is a semi-extension structure, the shortest distance between the top air outlet extension section 15 and the lens of the optical system 2 is D, and D is not greater than 300 mm.

[0030] When the number of optical systems of the SLM device further increases, the size limit of the distance D between the outer edge of the protection lens of the top air outlet extension section close to the side wall of the working cavity still holds. For SLM devices with a relatively large number of optical systems, which often have the characteristic that the distance from the outlet of the extended air outlet to the top baffle is relatively long, the present invention sets the top air outlet extension section 15 into a structure that spans below the protection mirror of the optical system, as Figure 3 shown, the structure in the working range area of the laser beam is hollowed out to avoid blocking the optical path. Through such a design method, the problem of the premature deflection area of the lens protection gas velocity direction can be effectively solved, ensuring that the gas film formed by the lens protection gas can completely cover the lower surfaces of all optical protection lenses of the SLM device, and further improving the stability of the lens protection effect of the device. That is, when the top air outlet extension section 15 is a full-extension structure, the top air outlet extension section 15 covers the optical system 2 and then extends to the lens protection gas top partition 18; through holes are provided at the projection position of the protection mirror of the optical system 2 on the top air outlet extension section 15; the diameter of the protection mirror of the optical system 2 is φ 镜 ; the aperture of the through hole is φ 孔 , φ 孔 ≥φ 镜 .

[0031] The lens protection air flow forming device further includes a lens protection air extension baffle 17 extending from the top of the forming chamber 1 towards the forming surface; the axial direction where the lens protection air extension baffle 17 is located is parallel to the flowing direction of the lens protection air flow; the height of the lens protection air extension baffle 17 is L, and L is not less than 1.2H; the distance between the lens protection air extension baffle 17 and the top air outlet extension section 15 is Y; Y is not greater than 30 mm.

[0032] See Figure 1 , the lens protection air flow forming device provided by the present utility model includes an air suction pipe 6, a filtration system 7, and a fan 8; the first air suction port 4 and the second air suction port 5 are respectively communicated with the filtration system 7 through the air suction pipe 6; the filtration system 7 is communicated with the top air outlet 14 through the fan 8. The lens protection air flow forming device further includes a flow splitting device; the fan 8 is respectively communicated with two top air outlets 14 through the flow splitting device; the flow splitting device is a pipe flow splitter with adjustable flow rate.

[0033] See Figure 1 , the lens protection air flow forming device provided by the present utility model only includes an additive manufacturing equipment flow field structure with lens protection effect and surface blowing effect, as Figure 1 shown, in the main working chamber forming chamber 1 of the SLM equipment, an optical system 2 with a galvanometer - field lens - protective lens structure is fixed at the top. High - energy - density laser irradiates the powder bed 3 at the bottom of the forming chamber through the optical system. During the sintering process, by - products such as metal splash particles generated in the molten pool are carried away by the first air suction port 4 and the second air suction port 5 on both sides of the bottom along with the air flow in the working chamber, and are gathered in the air suction pipe 6 and then collected and filtered by the filtration system 7. The fan 8 provides pressure lift for the circulating fluid and maintains the volume flow rate stable under the working state of the overall circulating atmosphere. The fan outlet is connected to the inlet position of the flow splitting tee 9 through a pipe.

[0034] The inert gas circulation volume flow rate is evenly distributed to the lens protection gas shunt devices 19 installed on both sides of the equipment working cavity through a flow-dividing tee device, and the consistency of the outlet velocities of the air outlets on the left and right sides at the top of the working cavity is improved through the internally preset flow channels and rectifying devices, forming a uniform and stable gas film under the protective lens of the optical system. The air outlets are closely attached to the upper surface 16 of the working cavity and are kept horizontal with the lower surface of the protective lens of the optical system 2. The top blowing air outlet extension sections 15 on both sides inside the working cavity near the top plate use solid walls to isolate the metal dust floating with the flow in the working cavity from contacting the upstream of the gas film. At the same time, lens protection gas extension baffles 17 are provided on both the front and rear sides of the lens protection gas flow region to block the metal dust from contacting both sides of the gas film, thereby achieving the long-term cleanliness of the protective lens of the optical system 2. Within a unit time, a gas film with a certain volume flow rate on the lower surface of the protective lens of the optical system is separated by the lens protection gas top partition 18 installed at the center position of the top plate of the working cavity, deflecting the velocity direction of the lens protection gas, deflecting the movement direction of the lens protection gas passing through the top blowing air outlet extension sections 15 on both sides of the working cavity to be vertically downward and flowing at high speed to the center of the powder bed of the working cavity. After the jet flow reaches the center of the powder bed width, the velocity stagnates to form a high-pressure area. Under the action of the pressure gradient, the flow field velocity undergoes a secondary deflection, and a wind field with a high consistency of velocity distribution is constructed between the high-pressure area where the velocity stagnates at the center of the width and the suction air outlets on both sides under the drive of the pressure difference, thereby effectively removing the by-products generated during the melting pool sintering process of the SLM equipment.

Claims

1. A lens protection air flow forming device, characterized in that: The lens protection air flow forming device includes at least two groups of top air inlets (14) and an air suction port disposed inside the forming chamber (1); at least two paths of lens protection air flows that sweep across the lower surface of the optical system protection mirror are conveyed into the forming chamber (1) through the top air inlets (14); the top air inlets (14) are in communication with the air suction port through the lens protection air flows.

2. The lens protection air flow forming device according to claim 1, wherein: The two groups of top air inlets (14) and the air suction port are arranged at intervals in the top area of the forming chamber.

3. The lens protection air flow forming device according to claim 1, characterized in that: The two top air inlets (14) are disposed at the tops of the opposite side walls of the forming chamber (1) respectively; the air suction port includes a first air suction port (4) and a second air suction port (5); the first air suction port (4) and the second air suction port (5) are disposed in the middle area of the top of the forming chamber; the two top air inlets (14) are respectively in communication with the first air suction port (4) and the second air suction port (5) through the lens protection air flows.

4. The lens protection air flow forming device according to claim 1, wherein: The two top air inlets (14) are placed at the middle position of the top of the forming chamber (1); the air suction port includes a first air suction port (4) and a second air suction port (5); the first air suction port (4) and the second air suction port (5) are respectively disposed on the side walls of the forming chamber (1) opposite to the two top air inlets (14).

5. The lens protection air flow forming device according to claim 1, wherein: The lens protection air flow forming device further includes a lens protection air top partition plate (18) placed at the middle position of the top of the forming chamber (1); the two top air inlets (14) are disposed at the tops of the opposite side walls of the forming chamber (1) respectively; the air suction port includes a first air suction port (4) and a second air suction port (5) located at the bottom of the side wall of the forming chamber; the first air suction port (4) and the second air suction port (5) are respectively disposed on the opposite side walls of the forming chamber (1); The same group of top air inlets and the air suction port are disposed on the same side wall of the forming chamber; the lens protection air flows blown out oppositely by the two top air inlets (14) are separated and guided by the lens protection air top partition plate (18) and then are respectively in communication with the first air suction port (4) and the second air suction port (5).

6. The lens protection air flow forming device according to claim 5, wherein: The lens protection air top partition plate (18) includes a web plate and wing plates provided on the web plate; the overall cross-section of the lens protection air top partition plate (18) is in a T shape; the wing plates are connected to the top of the forming chamber (1); the two paths of lens protection air flows are respectively guided by the web plate of the lens protection air top partition plate (18) and flow from the top of the forming chamber (1) to the forming width and then flow from the center of the forming width to both sides of the forming width along the forming width.

7. The lens protection air flow forming device according to claim 6, wherein: The lens protection air top partition plate (18) further includes a diversion plate disposed between the wing plates and the web plate and connected to the wing plates and the web plate respectively; the diversion plate is an arc-shaped diversion plate or an inclined plane diversion plate.

8. The lens protection air flow forming device according to any one of claims 1-7, characterized in that: The lens protection air flow forming device includes an air suction pipeline (6), a filtering system (7) and a fan (8); the air suction port is in communication with the filtering system (7) through the air suction pipeline (6); the filtering system (7) is in communication with the top air inlets (14) through the fan (8); the fan (8) is in communication with the two top air inlets (14) respectively through a flow dividing device; the flow dividing device is a pipeline flow divider with adjustable flow rate.

9. The lens protection air flow forming device according to claim 8, wherein: The lens protection air flow forming device further includes a top air outlet extension section (15); the top air outlet extension section (15) is in communication with the top air outlet (14); the top air outlet extension section (15) is of a semi-extension structure or a full-extension structure; the thickness of the top air outlet extension section (15) is H, and H is not less than 20 mm.

10. The lens protection air flow forming device according to claim 9, characterized in that: When the top air outlet extension section (15) is of a semi-extension structure, the shortest distance between the top air outlet extension section (15) and the protective lens of the optical system (2) is D, and D is not greater than 300 mm; When the top air outlet extension section (15) is a fully extended structure, the top air outlet extension section (15) covers the protective mirror of the optical system (2), and a through hole is provided on the top air outlet extension section (15) along the projection position of the protective mirror of the optical system (2) on the top air outlet extension section (15); the diameter of the protective mirror of the optical system (2) is φ 镜 ; the aperture of the through hole is φ 孔 , and the φ 孔 ≥ φ 镜 .

11. The lens protection air flow forming device according to claim 10, characterized in that: The lens protection air flow forming device further includes a lens protection air extension baffle (17) extending from the top of the forming chamber (1) to the forming width; the axis where the lens protection air extension baffle (17) is located is parallel to the flowing direction of the lens protection air flow; the height of the lens protection air extension baffle (17) is L, and L is not less than 1.2H; the distance between the lens protection air extension baffle (17) and the top air outlet extension section (15) is Y; Y is not greater than 30 mm.

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