Protective airflow forming device for additive manufacturing equipment

Abstract

The utility model belongs to the field of additive manufacturing, and relates to a protective airflow forming device for additive manufacturing equipment, which comprises an air blowing device, a first air suction port and a second air suction port which are all arranged in a forming chamber, the blowing device is communicated with the interior of the forming chamber; top central airflow is conveyed into the forming chamber through an air blowing device; the top central airflow flows from the top of the forming chamber to the forming breadth and forms powder bed protection airflow on the forming breadth; powder bed protection airflow flows from the center of the forming breadth to the two sides of the forming breadth; in the flowing direction of powder bed protection airflow, the first air suction opening and the second air suction opening are oppositely formed and located on the two side portions of the forming breadth. The protective airflow forming device for the additive manufacturing equipment can effectively reduce the slag falling amount of the breadth and obviously improve the forming quality of parts.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of additive manufacturing, and relates to a protective airflow forming device, in particular to a protective airflow forming device for additive manufacturing equipment. BACKGROUND

[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, multiple beams and strong robustness, so as to realize the production of larger size parts, higher printing efficiency, longer equipment stable working time and other goals. The protective atmosphere circulation filtering system in the traditional SLM equipment is an indispensable part. Since high-power laser is accompanied by the generation of metal vapor, metal droplet splashing and other by-products during the melting process on the metal powder bed, it is necessary to remove them in time to avoid the influence of floating and secondary deposition on the equipment working state. With the continuous updating and development of additive manufacturing equipment, the forming size is continuously increasing, and the traditional forming work cavity wind field structure is facing the problems of increasing powder bed layer thickness, interfering with the particle size distribution of the powder, and affecting the uniformity of the lower layer of the powder. Simply relying on increasing the mainstream area wind speed of the forming area can only solve the problem of falling slag, and excessive mainstream wind speed will cause economic loss due to blowing powder, and the sudden change of turbulence degree of the blowing port will intensify the unstable flow state of the melt in the molten pool and cause sintering defects. SUMMARY

[0003] In order to solve the above technical problems existing in the background art, the utility model provides a protective airflow forming device for additive manufacturing equipment which can effectively reduce the amount of falling slag of the forming area and obviously improve the forming quality of parts.

[0004] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0005] A protective airflow forming device for additive manufacturing equipment, characterized in that: the protective airflow forming device for additive manufacturing equipment comprises a blowing device, a first air suction port and a second air suction port which are uniformly arranged in the forming chamber; the blowing device is in communication with the inside of the forming chamber; the blowing device is used for conveying a top central airflow to the inside of the forming chamber; the top central airflow flows from the top of the forming chamber to the forming area and forms a powder bed protection airflow on the forming area; the powder bed protection airflow flows from the center of the forming area to the two sides of the forming area; along the flow direction of the powder bed protection airflow, the first air suction port and the second air suction port are oppositely arranged and located at the two sides of the forming area.

[0006] The blowing device comprises lens protection air outlets and a top partition plate; the top partition plate is arranged at the middle of the top of the forming chamber; the two lens protection air outlets are arranged on the side wall of the forming chamber in axial symmetry along the top partition plate; two lens protection air flows in opposite directions are sent to the inside of the forming chamber through the two lens protection air outlets; the two lens protection air flows are both swept from the lower surface of the optical system and then form a top central air flow through the top partition plate.

[0007] The top partition plate comprises a web plate and wing plates arranged on the web plate; the cross section of the top partition plate as a whole is T-shaped; the wing plates are connected with the top of the forming chamber; the two lens protection air flows form a top central air flow through the web plate of the top partition plate; preferably, the top partition plate further comprises a flow guide plate arranged between the wing plates and the web plate; the flow guide plate is an arc-shaped flow guide plate or an inclined flow guide plate.

[0008] The blowing device comprises a blowing flow guide member arranged at the top of the forming chamber; a top direct blowing air flow is sent to the inside of the forming chamber through the blowing flow guide member.

[0009] The blowing flow guide member comprises an inlet section, a turning section and an outlet section connected in sequence; the outlet section extends into the forming chamber from the top of the forming chamber; the inlet section is connected with the inside of the forming chamber through the turning section and the outlet section; the ratio of the caliber of the inlet section to the caliber of the outlet section is 1:0.95-1.25; the cross section of the inlet section is circular, rectangular or elliptical; the cross section of the outlet section is elliptical, waist-shaped or long rectangular combined with semi-elliptical.

[0010] A plurality of air guide partition plates are arranged on the outlet section; the air guide partition plates are arranged in parallel with the flow direction of the top direct blowing air flow in the axial direction; the plurality of air guide partition plates are arranged in axial symmetry along the center line of the outlet section; the end of each air guide partition plate is not in contact with the bottom of the outlet section; along the direction from the end of the long axis of the outlet section to the center line of the outlet section, the angle between the extension line of the end of the air guide partition plate and the bottom of the outlet section gradually increases; the vertical distance between the end of the air guide partition plate and the bottom of the outlet section gradually increases; preferably, the height of the outlet section is 80-150 mm.

[0011] The air blowing device further comprises a top air blowing cavity and a top partition plate; the top partition plate is arranged at a middle position of the top of the forming chamber and at the outlet of the air blowing flow guide; the axis of the top partition plate coincides with the axis of the long axis of the outlet of the air blowing flow guide; the top partition plate is in a disconnected structure or a slotted structure; the top air blowing lens protection gas air outlets are two, and the two top air blowing lens protection gas air outlets are symmetrically arranged on the side wall of the forming chamber along the axis of the top partition plate; two lens protection gas flows in opposite directions are delivered to the inside of the forming chamber through the two top air blowing lens protection gas air outlets; the two lens protection gas flows are swept from the lower surface of the optical system, guided through the top partition plate, and then combined with the top direct blowing gas flow from the air blowing flow guide to form a top central gas flow.

[0012] The sinking height of the top partition plate is greater than the sinking height of the air blowing flow guide in the forming chamber; preferably, the top partition plate comprises a web plate and a wing plate arranged on the web plate; the cross section of the top partition plate as a whole is in a T shape; the wing plate is connected to the top of the forming chamber; the two lens protection gas flows are swept from the lower surface of the optical system, guided through the web plate of the top partition plate, and then combined with the top direct blowing gas flow from the air blowing flow guide to form a top central gas flow; preferably, the top partition plate further comprises a flow guide plate arranged between the wing plate and the web plate; the flow guide plate is an arc-shaped flow guide plate or an inclined flow guide plate; the two lens protection gas flows are swept from the lower surface of the optical system, guided through the flow guide plate of the top partition plate, and then combined with the top direct blowing gas flow from the air blowing flow guide to form a top central gas flow.

[0013] The top partition plate is in a disconnected structure or a slotted structure;

[0014] When the top partition plate is in a disconnected structure, the top partition plate is two plates with the same structure; the two top partition plates are symmetrically arranged along the long axis direction of the outlet of the air blowing flow guide at the side of the air blowing flow guide; the two lens protection gas flows are swept from the lower surface of the optical system, guided through the top partition plate, and then combined with the top direct blowing gas flow from the air blowing flow guide to form a top central gas flow;

[0015] When the top partition plate is in a slotted structure, a groove is arranged on the axis of the top partition plate; the air blowing flow guide is embedded in the groove; the axis of the top partition plate coincides with the axis of the long axis of the outlet of the air blowing flow guide; the top direct blowing gas flow is divided through the air blowing flow guide and the web plate or the flow guide plate, and then combined with the two lens protection gas flows guided through the top partition plate to form a top central gas flow.

[0016] The blowing device further comprises a lens protection gas extension section extending from the top blowing cavity end to the middle position of the forming chamber interior; the lens protection gas extension section is parallel to the plane where the top of the forming chamber is located in the axial direction; the lens protection gas extension section is a half-extended structure or a fully-extended structure; the thickness of the lens protection gas extension section is H, and the H is not less than 20 mm.

[0017] When the lens protection gas extension section is a half-extended structure, the shortest distance between the lens protection gas extension section and the optical system lens is D, and the D is not greater than 300 mm.

[0018] When the lens protection gas extension section is a fully-extended structure, the lens protection gas extension section covers the middle position of the forming chamber after extending from the optical system protection lens; a through hole is arranged on the lens protection gas extension section at the projection position of the optical system protection lens on the lens protection gas extension section; the diameter of the optical system lens is φ 镜 ; the aperture of the through hole is φ 孔 , and the φ 孔 ≥ φ 镜 .

[0019] The blowing device further comprises a lens protection gas extension baffle extending from the top of the forming chamber to the forming web; the lens protection gas extension baffle is parallel to the flow direction of the lens protection gas flow in the axial direction; the height of the lens protection gas extension baffle is L, the height of the lens protection gas extension section is H, the L is not less than 1.2H; the distance between the lens protection gas extension baffle and the lens protection gas extension section is Y; the Y is not greater than 30 mm.

[0020] The protection gas flow forming device for the additive manufacturing equipment comprises a suction pipeline, a filtering system and a fan; the first suction port and the second suction port are respectively connected with the filtering system through the suction pipeline; the filtering system is connected with the blowing flow guide member and the top blowing cavity through the fan.

[0021] The protection gas flow forming device for the additive manufacturing equipment further comprises a shunt device, a gas flow shunt structure, a flow proportion control device and a rectifier; the fan is connected with the flow proportion control device and the gas flow shunt structure through the shunt device; the flow proportion control device is connected with the blowing flow guide member through the rectifier; the gas flow shunt structure is connected with the top blowing cavity; the shunt device is a flow-adjustable pipeline shunt; the flow proportion control device is a butterfly valve, a conical valve or a multi-hole orifice plate; the rectifier is a high-porosity honeycomb orifice plate or a multi-layer high-opening-ratio metal damping net.

[0022] The advantages of the utility model are:

[0023] This invention provides a protective airflow forming device for additive manufacturing equipment. The forming device uses a flow ratio control device to direct a portion of the circulating inert protective air of the additive manufacturing equipment to the forming surface through a guide structure at the top of the forming working chamber, forming a mainstream area evenly distributed from the center of the forming surface to the suction ports on both sides. Another portion passes through the cavity above the forming working chamber under static pressure and through small holes to form a uniform downward pressure flow field to protect the optical lens, or forms a lens protection flow field of a certain thickness below the protective lens through lens protection air extension sections arranged on both sides of the forming chamber, or a combination of both. This effectively suppresses the backflow of metal dust carried in the working chamber and prevents dust from adhering to the protective lens and causing contamination. The protective airflow forming device for additive manufacturing equipment provided by this invention effectively reduces the travel distance of sintering byproducts to the suction port. Compared with the traditional wind field structure of additive manufacturing equipment, it greatly reduces the amount of slag on the printing plate, improves the forming quality of parts, and increases the equipment's circulating flow rate through the flow ratio control structure. This enhances the suction force of the suction ports on both sides of the working chamber while strengthening the lens protective airflow velocity, forming a uniform and stable air film covering layer. This solves the problem of metal dust adhering to the protective lens causing the optical path to be blocked, reducing the printing plate sintering energy density and requiring frequent printing stops and box openings for cleaning. This invention effectively reduces the distance of splashed byproducts from the molten pool to the suction port during the sintering process of additive manufacturing equipment, to only 1 / 2 of the travel distance of splashed byproducts in the traditional additive manufacturing wind field structure. The smaller splash travel distance significantly improves the uniformity of the printing plate thickness and the consistency of powder particle size distribution. Combined with the wind field structure of lens protective gas and top blowing, a long-lasting and effective air film covering layer is constructed under the optical system protective lens, improving the stability of the optical system of ultra-large SLM equipment during long-term operation. The central jet of the top blowing area flows between the high-pressure zone and the low-pressure zone of the air inlet on both sides of the working chamber, forming a uniform spatial velocity distribution in the flow field under the pressure gradient, which effectively improves the consistency of velocity distribution in the sintering area of ​​the SLM equipment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the protective gas forming device for additive manufacturing equipment provided by this utility model;

[0025] Figure 2 This is a schematic diagram of the structure of three different types of air-blowing guides used in this utility model;

[0026] Figure 3 This is a side view of the long axis center section of the air blowing guide nozzle used in this utility model;

[0027] Figure 4 It is a comparison chart of the airflow guiding effects using different airflow guides;

[0028] Figure 5It is the wind field structure schematic diagram of the blowing flow guide air port adopted by the utility model;

[0029] Figure 6 It is the structure schematic diagram of blowing main stream area formed by the existing blowing flow guide port;

[0030] Figure 7 It is the structure schematic diagram of blowing main stream area of blowing flow guide port provided by the utility model;

[0031] Figure 8 It is the structure schematic diagram of embodiment 2 of the protective gas forming device for additive manufacturing equipment provided by the utility model;

[0032] Figure 9 It is the structure schematic diagram of embodiment 3 of the protective gas forming device for additive manufacturing equipment provided by the utility model;

[0033] Figure 10 It is the structure schematic diagram of top partition (disconnection type) adopted by the utility model;

[0034] Figure 11 It is the structure schematic diagram of top partition (slotted type) adopted by the utility model;

[0035] Figure 12 It is Figure 10 Or Figure 11 The overhead structure schematic diagram of;

[0036] Figure 13 It is the structure schematic diagram of embodiment 4 of the protective gas forming device for additive manufacturing equipment provided by the utility model;

[0037] Figure 14 It is the structure schematic diagram of two different forms of top partition adopted by the utility model;

[0038] Figure 15 It is the left and right side blowing additive manufacturing equipment extension air port and lens protective gas space flow field structure schematic diagram;

[0039] Figure 16 It is the structure schematic diagram of the protective gas forming device (top opposite suction) for additive manufacturing equipment provided by the utility model;

[0040] Figure 17 It is the structure schematic diagram of the protective gas forming device (top back suction) for additive manufacturing equipment provided by the utility model;

[0041] Among them:

[0042] 1 - forming chamber; 2 - optical system; 3 - powder bed; 4 - first suction port; 5 - second suction port; 6 - suction duct; 7 - filtration system; 8 - fan; 9 - flow splitting tee; 10 - flow proportioning control device; 11 - rectifier; 12 - air blowing guide; 121 - inlet section; 122 - turning section; 123 - outlet section; 13 - air flow splitting structure; 14 - lens protection air outlet; 15 - lens protection air extension section; 16 - upper surface of working cavity; 17 - lens protection air extension baffle; 18 - top partition; 19 - lens protection air splitting device; 20 - top air blowing cavity. DETAILED DESCRIPTION

[0043] The research and development idea of the protection air flow forming device for the additive manufacturing equipment is that a top central air flow is formed at the top of the forming chamber. The top center of the utility model is not the central position of the top of the forming chamber, but a region formed by extending outward from the central position. The area of the region is obviously smaller than the area of the top of the forming chamber. The top central air flow is derived from the direct blowing air flow at the top of the forming chamber and / or the lens protection air flow sweeping from the lower surface of the optical system. When the top central air flow contains the lens protection air flow, the lens protection air flow is two-way. The top central air flow flows from the top of the forming chamber to the forming surface and forms a powder bed protection air flow on the forming surface. The powder bed protection air flow flows from the center of the forming surface to the two sides of the forming surface. The top central air flow and the powder bed protection air flow as a whole form a shape of the Chinese character "。

[0044] The lens protection air flow blows from the middle of the forming chamber to the opposite sides of the forming chamber along the lower surface of the optical system, or blows from the opposite sides of the forming chamber to the middle of the forming chamber along the lower surface of the optical system. The thickness of the lens protection air flow is not less than 20 mm. When the lens protection air flow blows from the opposite sides of the forming chamber to the middle of the forming chamber along the lower surface of the optical system, one of the embodiments is that the lens protection air flow is collected or guided in the middle of the forming chamber to form a top central air flow, which flows from the top of the forming chamber to the forming surface and forms a powder bed protection air flow on the forming surface. The second embodiment is that the lens protection air flow is combined with the top direct blowing air flow in the middle of the forming chamber to form a top central air flow. The third embodiment is that a suction device is arranged at the middle position of the forming chamber to directly suck away the lens protection air flow collected in the middle position. At this time, the lens protection air flow does not converge with the top direct blowing air flow and does not participate in the formation of the top central air flow, as shown in Figure 16 When the lens protection air flow blows from the middle of the forming chamber to the opposite sides of the forming chamber along the lower surface of the optical system, a lens protection air flow blowing device is arranged at the middle position of the forming chamber to directly blow the lens protection air flow to the opposite sides of the forming chamber. The lens protection air flow is directly sucked away at the two sides of the forming chamber. The lens protection air flow is independent of the top direct blowing air flow, and is complementary to or interferes with the top direct blowing air flow. The lens protection air flow does not participate in the formation of the top central air flow, as shown in Figure 17 ​

[0045] The top direct blowing airflow of the forming chamber further comprises a downward pressing airflow uniformly distributed on the top of the forming chamber and arranged on the side of the top central airflow; the downward pressing airflow flows from the top of the forming chamber to the forming web.

[0046] The protection airflow forming device for additive manufacturing equipment provided by the utility model, along the flow direction of the protection airflow for additive manufacturing equipment, collects the inert protection airflow used by the additive manufacturing equipment through the circulating pipeline with good sealing performance, filters the circulating inert gas, obtains clean airflow, and then increases the speed and pressure of the clean airflow under the work of the fan and realizes recycling.

[0047] Exemplarily, referring to Figure 8 and Figure 9 , the utility model provides a kind of protection airflow forming device for additive manufacturing equipment based on as before, including blowing device, first air intake 4 and second air intake 5 being placed in the inside of forming chamber 1;Blowing device is penetrated with the inside of forming chamber 1;Top central airflow is transported to the inside of forming chamber 1 by blowing device;Top central airflow flows from the top of forming chamber 1 to forming web and forms powder bed protection airflow on forming web;Powder bed protection airflow flows along the center of forming web to both sides of forming web;Along the flow direction of powder bed protection airflow, first air intake 4 and second air intake 5 are oppositely arranged and are at both sides of forming web.

[0048] The blowing device used in the utility model is blowing flow guide piece 12 and / or top blowing lens protection gas air port 14, as long as top central airflow can be formed, it can be used in the scheme shown in the utility model. As only blowing flow guide piece 12 is used, as shown in Figure 1 , if only top blowing lens protection gas air port 14 is used, as shown in Figure 13 Structure. As preferred, referring to Figure 8 , the blowing device used in the utility model includes blowing flow guide piece 12, top blowing lens protection gas air port 14 and top baffle 18, that is, it includes the structure of blowing flow guide piece 12 and top blowing lens protection gas air port 14. Blowing flow guide piece 12 is arranged on the top of forming chamber 1;Top baffle 18 is placed in the middle position of the top of forming chamber 1 and is at the outlet of blowing flow guide piece 12;The axial direction of top baffle 18 coincides with the axis of the long axis of blowing flow guide piece 12 outlet;Top blowing lens protection gas air port 14 is two, two top blowing lens protection gas air ports 14 are symmetrically arranged on the side wall of forming chamber 1 along the axial direction of top baffle 18;Forming chamber top direct blowing airflow is transported to the inside of forming chamber 1 by blowing flow guide piece 12;Two-way flow direction opposite lens protection airflow is transported to the inside of forming chamber 1 by two top blowing lens protection gas air ports 14;Two-way lens protection airflow is guided by top baffle 18 after sweeping from the lower surface of optical system and respectively converges with forming chamber top direct blowing airflow to form top central airflow.

[0049] Referring to Figure 3 The blowing flow guide piece 12 comprises an inlet section 121, a turning section 122 and an outlet section 123 connected in sequence; the inlet section 121 is used for connecting the rectifier 11, the turning section 122 is a transition section in which the flow passage cross-sectional area starts to change; the outlet section 123 extends into the forming chamber 1 from the top of the forming chamber 1; the inlet section 121 is connected with the inside of the forming chamber 1 through the turning section 122 and the outlet section 123; the ratio of the caliber of the inlet section 121 to the caliber of the outlet section 123 is 1:0.95-1.25; the cross section of the inlet section 121 is circular, rectangular or elliptical; the cross section of the outlet section 123 is elliptical, waisted or long rectangular combined with semi-elliptical. As shown in Figure 2 As can be seen from (a) and (b) in Figure 2 (a) is shown as a circular inlet-elliptical flow guide outlet, Figure 2 (b) is shown as a rectangular inlet-long rectangular combined semi-elliptical flow guide outlet, when the downward projection position of the top blowing main flow area flow guide air port is located at the center of the forming surface, the inlet and outlet cross section center points of the flow guide air port coincide. As shown in Figure 2 (c) is the definition of the ratio of the flow passage cross-sectional area of the inlet and outlet of the blowing flow guide piece in the utility model, which is S inlet : S outlet When the ratio of the outlet and inlet flow passage cross-sectional area is too large, the expansion type flow guide outlet cannot effectively form a fan-shaped main flow area, and similarly, when the ratio of the outlet and inlet flow passage cross-sectional area is too small, the airflow acceleration of the contraction type flow guide outlet will affect the powder bed powder laying quality.

[0050] Referring to Figure 3 Since the blowing flow guide piece 12 is usually placed at the center position of the forming range of the equipment, the internal flow guide structure adopts a central symmetry mode, and the number of the flow guide pieces designed on one side of the blowing flow guide piece 12 is ≥2, Figure 3The number of the guide vanes is 3. That is, a plurality of air guide baffles are arranged on the outlet section 123; the air guide baffles are arranged in parallel with the flow direction of the straight blowing air flow at the top of the forming chamber in the axial direction; the air guide baffles are symmetrically arranged along the center line of the outlet section; the end of each air guide baffle is not in contact with the bottom of the outlet section; the angle between the extension line of the end of the air guide baffle and the bottom of the outlet section gradually increases in the direction from the end of the long axis of the outlet section to the center line of the outlet section; the vertical distance between the end of the air guide baffle and the bottom of the outlet section gradually increases; preferably, the height of the outlet section is 80-150 mm. For example, the air guide baffles along the long axis of the outlet section 123 include a first air guide baffle, a second air guide baffle, a third air guide baffle and a fourth air guide baffle in sequence; the first air guide baffle and the fourth air guide baffle are symmetrically arranged and have the same structure; the second air guide baffle and the third air guide baffle are symmetrically arranged and have the same structure; the first air guide baffle and the second air guide baffle are not in contact with the bottom of the outlet section 123. The structure of the air guide baffle is a circular arc or a flat folding plate, and here the flat folding plate is taken as an example.

[0051] Firstly, the height h of the blowing guide folding section 122 to the outlet section 123 is between 80-150 mm, and a too small height will aggravate the degree of flow separation, and a too large height will cause the main flow area to have a limited free diffusion distance in the working chamber and cannot effectively reduce the flow rate; the angle α between the side wall of the top blowing air port and the plane of the outlet section 123 is related to the overall height of the equipment working chamber and the powder bed and sintering forming range, and can be seen in Figure 5 a reasonable top blowing main flow area distribution region, in the side view of the central cross-section position, the main flow area needs to be fully diffused after contacting the powder bed plane, and the main flow area diffusion angle needs to completely cover the forming sintering area by the angle α between the side wall of the blowing guide and the powder bed plane, which corresponds to the angle α between the side wall of the blowing guide air port and the plane of the outlet section 123; the angle between the extension line of the first air guide baffle and the bottom of the outlet section 123 is β, and the vertical distance between the extension line of the first air guide baffle and the bottom of the outlet section 123 is b1; the angle between the extension line of the second air guide baffle and the bottom of the outlet section 123 is γ, and the vertical distance between the extension line of the second air guide baffle and the bottom of the outlet section 123 is b2; the angle between the side wall of the outlet section 123 and the bottom of the outlet section 123 is α; α≤β≤α+5°, 0≤b1≤20; β≤γ≤β+15°, b1≤b2≤40. In addition, the air guide baffle further includes a fifth air guide baffle and a sixth air guide baffle symmetrically arranged with the fifth air guide baffle and having the same structure; the first air guide baffle, the second air guide baffle, the fifth air guide baffle, the sixth air guide baffle, the third air guide baffle and the fourth air guide baffle are arranged in sequence along the long axis of the outlet section 123; the distance of the fifth air guide baffle from the center line of the outlet section 123 is c, A / 12≤c≤A / 3; A is the length of the long axis of the outlet section 123.

[0052] Only by defining the import and export cross-sectional shape, the flow control effect on the top blowing main flow area is limited, such as Figure 4 (a) shown, flow separation easily occurs near the long axis with large curvature change of inner wall surface, resulting in that the outlet velocity distribution cannot meet the design requirements of wind field. As shown in Figure 4 (b), by arranging a wind guide baffle inside the blowing guide, the influence of the flow separation of the inner wall boundary layer on the fan-shaped main flow area is weakened.

[0053] Referring to Figure 6 and Figure 7 , the velocity distribution comparison of the main flow area of the blowing guide with or without a guide plate in the center cross-sectional side view direction of the working cavity of the additive manufacturing equipment is shown, Figure 6 The flow separation occurs in the long axis inner wall of the guide air port, the fan-shaped main flow area is not fully diffused under the influence of the adverse pressure gradient, the overall flow field structure is narrow, the flow is concentrated, the flow rate is high, and the blowing powder problem is prone to occur. When the laser sintering position is at the edge of the forming area, the metal splash particle by-products generated by the molten pool in the fan-shaped main flow area cannot be effectively absorbed by the air suction ports on both sides, and the optical system protection lens is easily contaminated after a long time accumulation. Figure 7 With the assistance of the guide plate inside the blowing guide, the fan-shaped main flow area effectively covers the entire forming area, the flow field structure is fully diffused, the flow rate is reduced, the stability of the powder laying effect is improved, and a uniform flow field is constructed above the forming surface from the jet flow to the center area to the air suction ports on both sides.

[0054] Referring to Figure 10 and Figure 11 , in order to further reduce the turbulence intensity of the left and right lens protection gas in the optical top plate center area, a top baffle 18 is installed at the top of the equipment working cavity, which separates the left and right lens protection gas flow areas by using a solid wall at the center cross-sectional position of the equipment, and guides the lens protection gas to diffuse downward with the top blowing main flow area, and flows to the center of the powder bed with the main flow area. The sinking height of the top baffle 18 is greater than the sinking height of the blowing guide 12 in the forming chamber 1. The top baffle 18 includes a web and a wing plate arranged on the web; the cross section of the top baffle 18 is T-shaped as a whole; the wing plate is connected with the top of the forming chamber 1; the axis of the web coincides with the axis of the long axis of the outlet of the blowing guide 12; the two-way lens protection gas flows through the web of the top baffle 18. In order to reduce the turbulence intensity of the left and right lens protection gas when flowing to the top baffle of the lens protection gas, as shown in Figure 14As shown, the top baffle 18 reduces the vortex area of the lens protection gas in contact with the solid wall through the circular arc side structure (or flat plate bevel structure), which not only deflects the direction of the airflow velocity, but also effectively reduces the consistency of the front and rear direction, i.e. the X direction flow distribution in the figure, in the working cavity. That is, the top baffle 18 also includes a guide plate placed between the wing plate and the web plate; the guide plate is an arc guide plate or a bevel guide plate; the two-way lens protection gas flows through the guide plate.

[0055] Figure 10 And Figure 11 Two structures of the top baffle 18 are respectively shown as Figure 10 As shown, the top baffle 18 is installed only on the front and rear sides of the blowing guide member 12, that is, the top baffle 18 is in a disconnected form, and as Figure 11 As shown, the top baffle 18 is in a slot type, and the slot is used for embedding the blowing guide member 12. When the top baffle 18 is in a disconnected form, the top baffle 18 is two pieces of the same structure; the two pieces of the top baffle 18 are symmetrically arranged on the side of the blowing guide member 12 along the long axis direction of the outlet of the blowing guide member 12, and the axis direction of the top baffle 18 coincides with the axis direction of the long axis of the outlet of the blowing guide member 12; the top central airflow is formed by the top straight blowing airflow guided by the blowing guide member 12 and the lens protection airflow guided by the top baffle 18. When the top baffle 18 is in a slot type, the top baffle 18 is provided with a groove along the axis direction of the top baffle 18; the blowing guide member 12 is embedded in the groove; the axis direction of the top baffle 18 coincides with the axis direction of the long axis of the outlet of the blowing guide member 12; the top central airflow is formed by the top straight blowing airflow guided by the blowing guide member 12 and the lens protection airflow guided by the top baffle 18.

[0056] Referring to Figure 12, the top blowing combines with the left and right side lens protection gas wind field structure equipment work cavity top plate optical system protection lens below the wind field structure, the left and right side lens protection gas after passing through the lens protection gas air port 14 and the lens protection gas extension section 15, forms the uniform gas film cover layer below the optical lens, after being constrained by the top baffle 18 in the central region, the lens protection gas speed direction deflects downward, and the top blowing mainstream area converges to form the central airflow and flows to the powder bed surface. That is, the blowing device further comprises a lens protection gas extension section 15 extending from the end of the top blowing lens protection gas air port 14 to the top baffle 18; the lens protection gas extension section 15 is parallel to the plane where the top of the forming chamber 1 is located; the lens protection gas extension section 15 is a half-extended structure or a full-extended structure; the thickness of the lens protection gas extension section 15 is H, which is not less than 20mm, so as to ensure that the lens protection gas film has sufficient thickness to effectively cover the surface of the optical system 2 protection lens. When the lens protection gas extension section 15 is a half-extended structure, the shortest distance between the lens protection gas extension section 15 and the lens of the optical system 2 is D, which is not greater than 300mm. That is, when the number of optical systems of the SLM device further increases, as shown in Figure 9 , the size limit of the distance between the lens protection gas extension section and the distance D between the edge of the protection lens close to the outer side of the working cavity side wall still holds. For SLM devices with a large number of optical systems, the distance between the extension air port outlet and the top baffle is often long. The utility model sets the lens protection gas extension section 15 to span the structure below the optical system protection lens, as shown in Figure 15 , the structure of the laser beam working range area is hollowed out to avoid shielding the optical path. Through such a design method, the problem of the lens protection gas speed direction deflection area being advanced can be effectively solved, ensuring that the lens protection gas film can completely cover the lower surface 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 lens protection gas extension section 15 is a full-extended structure, the lens protection gas extension section 15 extends to the top baffle 18 after covering the optical system 2; a through hole is arranged on the lens protection gas extension section 15 at the projection position of the optical system 2 on the lens protection gas extension section 15; the diameter of the lens of the optical system 2 is φ 镜 ; the aperture of the through hole is φ 孔 , and φ 孔 ≥ φ 镜 .

[0057] Figure 10 and Figure 11The center section view of the structure of the top blowing combined with the two side lens protection gas flow field is shown, and the blowing device further comprises a lens protection gas extension baffle 17 extending from the top of the forming chamber 1 to the forming width; the axis of the lens protection gas extension baffle 17 is perpendicular to the axis of the top partition plate 18; the height of the lens protection gas extension baffle 17 is L, and L is not less than 1.2H; the distance between the lens protection gas extension baffle 17 and the lens protection gas extension section 15 is Y; Y is not greater than 30mm.

[0058] Referring to Figure 1 , Figure 8 , Figure 9 and Figure 13 , the protection gas flow forming device for additive manufacturing equipment comprises a suction pipeline 6, a filtering system 7 and a fan 8; the first suction port 4 and the second suction port 5 are respectively connected with the filtering system 7 through the suction pipeline 6; the filtering system 7 is connected with the blowing flow guide 12 and the top blowing cavity 20 through the fan 8.

[0059] Referring to Figure 9 , the protection gas flow forming device for additive manufacturing equipment further comprises a flow splitting device, a gas flow splitting structure 13, a flow proportion control device 10 and a rectifier 11; the fan 8 is connected with the flow proportion control device 10 and the gas flow splitting structure 13 through the flow splitting device; the flow proportion control device 10 is connected with the blowing flow guide 12 through the rectifier 11; the gas flow splitting structure 13 is connected with the top blowing cavity 20; the flow splitting device is a flow-adjustable pipeline splitter; the flow proportion control device 10 is a butterfly valve, a conical valve or a multi-hole orifice plate; the rectifier 11 is a high-porosity honeycomb orifice plate or a multi-layer high-opening-ratio metal damping net.

[0060] The following will make a detailed description of the schemes recorded or covered by the utility model in combination with the drawings:

[0061] Example 1 top blowing scheme

[0062] Referring to Figure 1 , the protection gas flow forming device for additive manufacturing equipment only comprises top blowing. The SLM equipment mainly comprises a forming chamber 1 which is provided with an optical system 2 of a galvanometer-field lens-protection lens structure at the top, a high-energy-density laser irradiates the powder bed 3 at the bottom of the forming chamber through the optical system 2, the metal droplet splashing particles and other by-products generated in the sintering process flow in the working cavity and are taken away by the first suction port 4 and the second suction port 5 at the two sides of the bottom, and are collected in the suction pipeline 6 to the filtering system 7 for centralized filtering treatment, the fan 8 provides pressure rise for the circulating fluid and maintains the volume flow to be stable in the overall circulating atmosphere working state, and the fan outlet is connected to the inlet of the flow splitting tee joint 9 through a pipeline.

[0063] Wherein, the flow dividing tee 9 divides the total circulation flow into two branches, wherein the upper top blowing main flow area branch passes through the flow proportion control device 10 and the flow straightening device 11, enters the working cavity through the blowing flow guide 12 to form a fan-shaped jet flow, flows to the center of the powder bed 3 at the bottom of the forming chamber, and the speed stagnation forms a high pressure area to form a wind field structure above the forming area from the center high pressure area to the left and right air inlets, so that the by-products such as metal vapor, plasma plume and molten pool splashing metal particles generated in the high-energy density laser sintering process are removed along with the flow; the other branch, i.e. the right lens protection gas branch, enters the top blowing cavity 20 at the top of the working cavity through the airflow dividing structure 13, and forms a uniform downward flow field under the differential pressure resistance of the outlet orifice plate at the lower side of the cavity, so as to isolate the metal smoke floating in the working cavity and realize effective protection of the optical lens.

[0064] Particularly, the flow dividing tee 9 is a special designed special-shaped tee pipe structure, which adjusts the ratio of the flow area of the upper top blowing main flow area branch and the flow area of the right lens protection branch at the flow dividing section to realize rough flow control, and combines the resistance adjustment of the flow proportion control device 10 such as butterfly valve, conical valve, porous orifice plate and the like to realize accurate control of the proportion of the flow of the top blowing main flow area branch and the total circulation flow. The flow straightening device 11 usually adopts a honeycomb orifice plate with high porosity or a multi-layer metal damping net with high opening ratio, so as to improve the uniformity of the inlet velocity distribution of the blowing flow guide 12. The airflow dividing structure 13 in the lens protection gas branch uniformly inputs the flow into the top blowing cavity 20, and the thickness of the cavity is greater than or equal to 30mm, so that the differential pressure resistance of the effective distribution orifice plate outlet airflow flow is realized, so that the uniform downward lens protection flow field is realized.

[0065] Example 2 top blowing and left and right side lens protection gas wind field structure

[0066] Referring to Figure 8 The additive manufacturing equipment protection gas flow forming device provided by the utility model includes a top blowing main flow area and left and right side lens protection gas wind field structure. With the increasing number of lasers in the pursuit of higher printing efficiency of additive manufacturing equipment, the area of the optical system 2 occupying the top plate space of the working cavity will be more and more, so that the area covered by the outlet orifice plate at the lower side of the top blowing cavity is further reduced, and a uniform downward top blowing lens protection downward flow field cannot be formed. The utility model provides a top blowing combined with left and right side lens protection gas wind field structure, as shown in Figure 8The SLM device is mainly composed of a working cavity forming chamber 1, an optical system 2 of a galvanometer-field lens-protection lens structure fixed on the top of the working cavity forming chamber 1, and a high-energy-density laser irradiated on a powder bed 3 at the bottom of the forming chamber through the optical system. During the sintering process, the molten pool generates metal splashing particles and other by-products, which are taken away by the first air suction port 4 and the second air suction port 5 at the bottom of the working cavity and then gathered in the air suction pipeline 6 to the filtering system 7 for centralized filtering treatment. The fan 8 provides pressure rise for the circulating fluid and maintains the overall circulating atmosphere working state to tend to be stable. The fan outlet is connected to the inlet position of the split tee 9 through the pipeline.

[0067] The split tee 9 divides the overall circulating flow into two branches. The upper top blowing main flow area branch passes through the flow proportion control device 10 and the flow regulating device 11, enters the working cavity through the blowing flow guide 12 to form a fan-shaped jet, flows to the center of the powder bed 3 at the bottom of the forming chamber, and forms a high-pressure area due to the speed stagnation, thereby forming a wind field structure from the high-pressure area in the center to the air suction ports on the left and right sides above the forming area. The metal vapor, plasma plume, molten pool splashing metal particles and other by-products generated during the high-energy-density laser sintering process are removed with the flow (this part is the same as that in Example 1); the other branch, i.e., the lens protection gas branch, enters the lens protection gas split device 19 installed on the left and right sides of the working cavity through the split structure 13, and the internal preset flow channel and the flow regulating device improve the consistency of the outlet velocity of the air ports on the left and right sides of the working cavity. The air ports are in close contact with the upper surface 16 of the working cavity and are horizontally arranged with the lower surface of the protection lens of the optical system 2. The lens protection gas extension section 15 near the top plate in the left and right sides of the working cavity uses a solid wall to isolate the metal smoke from contacting the gas film upstream in the working cavity, and the lens protection gas extension baffle 17 on the front and rear sides of the lens protection gas flow domain blocks the metal smoke from contacting the gas film on the two sides, thereby realizing long-term cleaning of the protection lens of the optical system 2.

[0068] For example, referring to Figure 16 Two air suction ports are arranged at the middle position of the forming chamber, and air supply ports are arranged on the side wall of the forming chamber. The lens protection gas flow is blown to the middle position (i.e., the air suction port) of the forming chamber. At this time, due to the presence of the air suction port, the lens protection gas flow is directly sucked away and does not converge with the top direct blowing flow, does not participate in the formation of the top central flow, and is independent of the top direct blowing flow. Referring to Figure 17 Two air suction ports are arranged on the opposite sides of the side wall of the forming chamber, and two air supply ports are arranged at the middle position (close to the top direct blowing flow) of the forming chamber. The lens protection gas flow is blown to the two sides (i.e., the air suction port) of the forming chamber. At this time, the lens protection gas flow only participates in the lens protection work and does not converge with the top direct blowing flow, does not participate in the formation of the top central flow, and is independent of the top direct blowing flow.

[0069] Example 3: Additive manufacturing wind field structure with left and right air blowing

[0070] Referring to Figure 13 The protective gas flow forming device for additive manufacturing equipment provided by the utility model only includes the additive manufacturing equipment flow field structure with lens protection effect and width air blowing effect, as shown in Figure 13 The SLM equipment main working cavity forming chamber 1 has an optical system 2 of a galvanometer-field lens-protection lens structure fixed at the top, a high-energy-density laser irradiates the forming chamber bottom powder bed 3 through the optical system, and the molten pool generates metal splashing particles and other byproducts during the sintering process, which are taken away by the first air suction port 4 and the second air suction port 5 on the bottom two sides and gathered to the filtering system 7 in the air suction pipeline 6 for centralized filtering treatment. The fan 8 provides pressure rise for the circulating fluid and maintains the volume flow to be stable in the overall circulating atmosphere working state. The fan outlet is connected to the inlet position of the shunt tee 9 through the pipeline. The part is the same as in example 1.

[0071] The inert atmosphere circulating volume flow is uniformly distributed to the lens protection gas shunt device 19 installed on the two sides of the equipment working cavity through the shunt tee device, and the internal preset flow channel and the flow regulating device improve the consistency of the outlet speed of the wind port on the left and right sides of the top of the working cavity, forming a uniform and stable gas film below the protection lens of the optical system. The wind port is in close contact with the upper surface 16 of the working cavity and maintains the level with the lower surface of the protection lens of the optical system 2. The lens protection gas extension section 15 near the top plate on the two sides of the working cavity inside uses a solid wall to isolate the metal smoke in the working cavity from contacting the upstream of the gas film, and the lens protection gas extension baffle 17 on the front and back of the lens protection gas flow domain blocks the metal smoke from contacting the two sides of the gas film, thereby realizing long-term cleaning of the protection lens of the optical system 2. In a unit of time, the gas film with a certain volume flow on the lower surface of the protection lens of the optical system is separated by the top partition plate 18 installed at the center of the top plate of the working cavity, which deflects the direction of the lens protection gas. The speed of the lens protection gas on the left and right sides of the working cavity through the lens protection gas extension section 15 is deflected vertically downward and flows at high speed to the center of the powder bed of the working cavity. After the jet flow direction reaches the center of the powder bed, the speed stagnates to form a high-pressure area. Under the action of the pressure gradient, the flow field speed realizes secondary deflection, and a wind field with high speed distribution consistency is constructed between the speed stagnation high-pressure area in the center of the width and the two sides of the air suction port under the driving of the pressure difference, thereby effectively taking away the byproducts generated by the molten pool sintering during the working process of the SLM equipment.

Claims

1. A protective gas flow forming device for an additive manufacturing apparatus, characterized by: The additive manufacturing equipment uses the protection gas flow forming device, which includes a blowing device, a first air suction port (4) and a second air suction port (5) arranged in the forming chamber (1); the blowing device is in communication with the inside of the forming chamber (1); the top central gas flow is sent to the inside of the forming chamber (1) through the blowing device; the top central gas flow flows from the top of the forming chamber (1) to the forming surface and forms a powder bed protection gas flow on the forming surface; The powder bed protection gas flow flows from the center of the forming surface to the two sides of the forming surface; The first air suction port (4) and the second air suction port (5) are oppositely arranged on the two sides of the forming surface along the flow direction of the powder bed protection gas flow; the blowing device includes a lens protection gas extension baffle (17) extending from the top of the forming chamber (1) to the forming surface; the blowing device is a top air supply structure and / or a side air supply structure; The blowing device of the top air supply structure includes a blowing flow guide piece (12) arranged at the top of the forming chamber (1); the forming chamber top direct blowing gas flow is sent to the inside of the forming chamber (1) through the blowing flow guide piece (12); The blowing flow guide piece (12) includes an inlet section (121), a turning section (122) and an outlet section (123) connected in sequence; the outlet section (123) extends into the forming chamber (1) from the top of the forming chamber (1); the inlet section (121) is in communication with the inside of the forming chamber (1) through the turning section (122) and the outlet section (123); the diameter ratio of the inlet section (121) to the outlet section (123) is 1:0.95-1.25; the cross section of the inlet section (121) is circular, rectangular or elliptical; the cross section of the outlet section (123) is elliptical, waist-shaped or long rectangular combined with half-elliptical.

2. The protective gas flow forming device for an additive manufacturing apparatus according to claim 1, characterized by: A plurality of air guide partitions are arranged on the outlet section (123); the axial direction of the air guide partitions is parallel to the flow direction of the forming chamber top direct blowing gas flow; the plurality of air guide partitions are symmetrically arranged along the center line of the outlet section (123); the end of each air guide partition is not in contact with the bottom of the outlet section (123); along the direction from the end of the long axis of the outlet section (123) to the center line of the outlet section (123), the included angle between the extension line of the end of the air guide partition and the bottom of the outlet section (123) gradually increases; the vertical distance between the end of the air guide partition and the bottom of the outlet section (123) gradually increases.

3. The protective gas flow forming device for an additive manufacturing apparatus according to claim 2, characterized by: The height of the outlet section (123) is 80-150 mm.

4. The protective gas flow forming device for an additive manufacturing apparatus according to claim 1 or 2 or 3, characterized by: The air blowing device further comprises a lens protection air outlet (14) and a top partition plate (18); the top partition plate (18) is arranged at the middle position of the top of the forming chamber (1) and at the outlet of the air blowing flow guide (12); the axis of the top partition plate (18) coincides with the axis of the long axis of the outlet of the air blowing flow guide (12); the top partition plate (18) is in a disconnected structure or a slotted structure; the lens protection air outlet (14) is two, and the two lens protection air outlets (14) are symmetrically arranged on the side wall of the forming chamber (1) along the axis of the top partition plate (18); two lens protection air flows in opposite directions are delivered to the inside of the forming chamber (1) through the two lens protection air outlets (14); the two lens protection air flows are swept from the lower surface of the optical system, guided by the top partition plate (18) and then respectively combined with the straight blowing air flow at the top of the forming chamber from the air blowing flow guide (12) to form a top central air flow.

5. The apparatus for forming a protective gas flow for an additive manufacturing apparatus according to claim 4, characterized by: The air blowing device further comprises a lens protection air extension section (15) extending from the end of the lens protection air outlet (14) to the middle position of the inside of the forming chamber (1); the axis of the lens protection air extension section (15) is parallel to the plane of the top of the forming chamber (1); the lens protection air extension section (15) is in a half-extended structure or a full-extended structure; the thickness of the lens protection air extension section (15) is H, and the H is not less than 20 mm.

6. The apparatus for forming a protective gas flow for an additive manufacturing apparatus according to claim 5, characterized by: When the lens protection air extension section (15) is in a half-extended structure, the shortest distance from the end of the lens protection air extension section (15) to the lens of the optical system (2) is D, and the D is not greater than 300 mm. When the lens protection gas extension section (15) is a full extension structure, the lens protection gas extension section (15) is covered behind the optical system (2) protection lens and extends to the middle position of the forming chamber (1); a through hole is arranged on the lens protection gas extension section (15) at the projection position of the optical system (2) protection lens; the diameter of the optical system (2) lens is φ 镜 ; the aperture of the through hole is φ 孔 , and φ 孔 ≥ φ 镜 .

7. The protective gas flow forming device for an additive manufacturing apparatus according to claim 6, characterized by: The axis of the lens protection air extension baffle (17) is parallel to the flow direction of the lens protection air flow; the height of the lens protection air extension baffle (17) is L, the height of the lens protection air extension section (15) is H, the L is not less than 1.2H; the distance between the lens protection air extension baffle (17) and the lens protection air extension section (15) is Y; the Y is not greater than 30 mm.

8. The apparatus for forming a protective gas flow for an additive manufacturing apparatus according to claim 7, characterized by: The protection air flow forming device for the additive manufacturing equipment comprises an air suction pipeline (6), a filtering system (7) and a fan (8); the first air suction port (4) and the second air suction port (5) are respectively connected with the filtering system (7) through the air suction pipeline (6); the filtering system (7) is connected with the air blowing flow guide (12) and the top air blowing cavity (20) through the fan (8).

9. The apparatus for forming a protective gas flow for an additive manufacturing apparatus according to claim 8, characterized by: The additive manufacturing equipment with the protection gas flow forming device further comprises a flow dividing device, a gas flow dividing structure (13), a flow proportion control device (10), and a rectifying device (11); the fan (8) is in communication with the flow proportion control device (10) and the gas flow dividing structure (13) through the flow dividing device; the flow proportion control device (10) is in communication with the blowing flow guide (12) through the rectifying device (11); the gas flow dividing structure (13) is in communication with the lens protection gas outlet (14); the flow dividing device is a flow-dividing pipe; the flow proportion control device (10) is a butterfly valve, a conical valve or a porous orifice plate; and the rectifying device (11) is a honeycomb orifice plate with high porosity or a multi-layer metal damping net with a high opening ratio.

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