CN113714519B

CN113714519B - Additive manufacturing device and method

Info

Publication number: CN113714519B
Application number: CN202111292198.1A
Authority: CN
Inventors: 程康康; 朱纪磊; 李会霞; 车倩颖; 王宇; 贺卫卫; 向长淑
Original assignee: Xi'an Sailong Metal Materials Co ltd
Current assignee: Xi'an Sailong Additive Technology Co ltd
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2022-04-08
Anticipated expiration: 2041-11-03
Also published as: CN113714519A

Abstract

The embodiment of the disclosure relates to an additive manufacturing device and method, which comprises a forming bin, a forming substrate, an electron beam heat source, a powder bin group, a movable powder feeding unit and a control unit. The invention reduces the impurity content in the printing parts due to the high vacuum clean environment, prevents the brittleness problem deterioration caused by the over high impurity concentration, and solves the difficult problem of difficult processing of double metals or multiple metals by adopting a plurality of powder bins and movable powder feeding units. Meanwhile, the bimetal component with a complex shape can be directly formed, subsequent machining and heat treatment are not needed, the utilization rate of materials is improved, compared with the traditional machining process, the manufacturing period is greatly shortened, and the cost is saved. And multiple multi-layer scanning is adopted at the fusion bonding interface, so that the bonding strength of the bonding position is increased.

Description

Additive manufacturing device and method

Technical Field

The embodiment of the disclosure relates to the technical field of metal additive manufacturing, in particular to an additive manufacturing device and method.

Background

The bimetal/multi-metal composite material is formed by combining two or more layers of metal alloys, has wide usability and technological properties due to the advantages of two metals or a plurality of metals, and can replace expensive materials or scarce metals in actual production due to the special structure and the performance of the bimetal/multi-metal composite material. Nowadays, many bimetallic materials are put into production, such as steel plates, steel bars, steel wires, steel pipes, etc. In terms of the selection of metal materials, the components mainly stressed are generally made of metal with larger thickness, and in order to save cost, the base materials mainly stressed are made of cheaper metal. Different coatings are selected as another material according to the requirements of the bimetallic material/multi-metal material, and the metals of the coatings are all made of precious or rare metal materials, so that the performance indexes required by the bimetallic material, such as stronger wear resistance, corrosion resistance or higher mechanical strength, are realized.

The existing bimetal/multi-metal processing technology comprises the existing explosion cladding technology, rolling cladding method, powder metallurgy method and the like, firstly, the complexity of the processing method causes the processing technology to be more complicated, the production efficiency is lower and the cost is higher; secondly, most methods cannot directly form product parts, the forming of an integral structural part is realized by a welding method, and the performance of a welding joint is complex due to the difference of materials in welding; third, the bi-metallic or multi-metallic bonding interface is easily made the weakest point in the overall material or structure using conventional methods. According to the existing selective laser melting technology, because an energy source is laser, a refractory metal material is difficult to form, a refractory metal is often adopted as a second metal for structural parts with better performance, meanwhile, the residual stress of laser printing parts is more, the brittle material is not easy to form, and because the linear expansion coefficient difference between double metals is possibly very large, the stress concentration is more likely to occur, the quality of the structural parts is poor, and the yield of products is influenced.

Accordingly, there is a need to ameliorate one or more of the problems with the related art solutions described above.

It is noted that this section is intended to provide a background or context to the disclosure as recited in the claims. The description herein is not admitted to be prior art by inclusion in this section.

Disclosure of Invention

It is an object of embodiments of the present disclosure to provide an additive manufacturing apparatus and method, which overcome, at least to some extent, one or more of the problems due to limitations and disadvantages of the related art.

According to a first aspect of embodiments of the present disclosure, there is provided an additive manufacturing apparatus comprising:

a forming bin, the interior of which is in a vacuum environment;

the forming base plate is arranged in the forming bin;

the electron beam heat source is arranged above the forming bin and used for providing a heat source;

the powder bin group at least comprises two powder bins which are respectively arranged on the peripheral sides of the forming bins and used for providing powder;

the movable powder feeding unit is arranged on one side of the electron beam heat source, and at least two accurate powder bins are arranged in the movable powder feeding unit and used for paving powder in a preset selection area;

and the control unit is used for controlling the electron beam heat source, the powder bin group and the movable powder feeding unit.

In an embodiment of the present disclosure, the powder bin set includes three powder bins, including a first powder bin, a second powder bin and a third powder bin, the first powder bin is disposed on a first side of the forming bin for disposing the first powder, the second powder bin is disposed on a second side of the forming bin for disposing the second powder, and the third powder bin is disposed above the first powder bin or the second powder bin for disposing the third powder.

In an embodiment of the disclosure, a vibration unit is disposed in the third powder bin, and is configured to enable the third powder bin to discharge powder in a vibration manner.

In an embodiment of the present disclosure, the movable powder feeding unit is provided with three accurate powder bins, including a first accurate powder bin, a second accurate powder bin and a third accurate powder bin, and the first accurate powder bin, the second accurate powder bin and the third accurate powder bin are respectively provided with the first powder, the second powder and the third powder.

In an embodiment of the disclosure, the powder feeding device further comprises a powder sucking unit arranged on the movable powder feeding unit.

In an embodiment of the disclosure, a forming substrate lifting unit is arranged at the bottom of the forming substrate and used for adjusting the horizontal height of the forming substrate to adjust the powder spreading thickness, and the powder spreading thickness is 0.03 mm-0.1 mm.

According to a second aspect of embodiments of the present disclosure, there is also provided an additive manufacturing method applied to any one of the additive manufacturing apparatuses described above, the method including:

acquiring slice data of each layer of a part model to be printed;

and according to the slicing data, paving powder by using the powder bin group, and paving powder on the forming platform and paving powder on the preset selected area by using the movable powder feeding unit.

In one embodiment of the present disclosure, the powders mixed during printing are subjected to particle size distribution according to different particle sizes.

In an embodiment of the disclosure, before the movable powder feeding unit spreads the powder, the powder suction unit is used to suck the powder in the preset selection area, the suction force of the powder suction unit can be controlled, and the precision of the powder suction selection area can reach 0.02-0.05 mm.

In an embodiment of the disclosure, when the transition layer surface is printed, the electron beam heat source turns clockwise to scan and an included angle between two consecutive scans is 45 degrees to 90 degrees, the transition layer surface is preset to m layers, and each layer needs to be preset to scan n times, wherein m =2 to 4, and n =1 to 3.

The technical scheme provided by the embodiment of the disclosure can have the following beneficial effects:

in the embodiment of the disclosure, the electron beam is used as an energy source, the advantages of high energy density and high utilization rate of the electron beam are utilized, the high density of the formed refractory metals and brittle materials is ensured, the formed substrate is preheated by utilizing the characteristic of rapid scanning of the electron beam heat source, the extremely high part forming temperature is ensured, the phenomenon that the residual stress generated by cooling different materials due to different thermal expansion coefficients is too large, so that more defects are generated on the parts is reduced, and the risk of deformation and cracking is greatly avoided. The clean environment in high vacuum has reduced the impurity content in the printing part, prevents to worsen because of the fragility problem that impurity concentration too high leads to, adopts a plurality of powder storehouses and portable powder feeding unit moreover, has solved the difficult problem of bimetal or many metals difficult processing. Meanwhile, the bimetal component with a complex shape can be directly formed, subsequent machining and heat treatment are not needed, the utilization rate of materials is improved, compared with the traditional processing technology, the manufacturing period is greatly shortened, the cost is saved, and the bonding strength of a bonding part is increased by adopting a multi-time multi-layer scanning mode on a melting bonding interface; the invention adopts the optimized powder granularity distribution and recovery technology, and improves the powder additive manufacturing applicability and the printing quality.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.

Fig. 1 shows a schematic view of an additive manufacturing apparatus in an example embodiment of the disclosure;

fig. 2 shows a flow chart of an additive manufacturing method in an exemplary embodiment of the disclosure;

FIG. 3 shows a schematic view of a sifting unit in an exemplary embodiment of the present disclosure;

FIG. 4 illustrates a schematic view of a preheat region in an exemplary embodiment of the present disclosure;

FIG. 5 shows a schematic powder classification in an exemplary embodiment of the present disclosure;

fig. 6 shows a schematic diagram of a transition layer and a scanning manner in an exemplary embodiment of the disclosure.

100. A forming bin; 110. forming a substrate; 120. a forming platform; 130. a forming substrate lifting unit; 200. an electron beam heat source; 310. a first powder bin; 320. a second powder bin; 330. a third powder bin; 331. a vibration unit; 400. a movable powder feeding unit; 410. a first accurate powder bin; 420. a second accurate powder bin; 430. a third accurate powder bin; 510. a first scraper unit; 520. a second scraper unit; 610. a first powder falling unit; 620. a second powder falling unit; 710. a first lifting unit; 720. a second lifting unit; 800. a powder suction unit; 900. a control unit.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Furthermore, the drawings are merely schematic illustrations of embodiments of the disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repetitive description will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities.

In this example embodiment, an additive manufacturing apparatus is first provided. The additive manufacturing apparatus may comprise:

the forming device comprises a forming bin 100, wherein a forming substrate 110 is arranged in the forming bin 100, an electron beam heat source 200 is arranged right above the forming bin 100, a powder bin group is arranged outside the forming bin 100, a movable powder feeding unit 400 is arranged on one side of the electron beam heat source 200, and the electron beam heat source 200 and the movable powder feeding unit 400 are electrically connected with a control unit 900.

Through the additive manufacturing device, the electron beam is used as an energy source, the advantages of high energy density and high utilization rate of the electron beam are utilized, the high density of the formed refractory metal and brittle materials is ensured, the formed substrate 110 is preheated by utilizing the characteristic of fast scanning of the electron beam, the extremely high part forming temperature is ensured, the phenomenon that the residual stress generated by cooling different materials due to different thermal expansion coefficients is too large, the parts generate more defects is favorably reduced, and the risk of deformation and cracking is greatly avoided. The clean environment of high vacuum has reduced the impurity content in the printing part, prevents that the fragility problem that leads to because of impurity concentration is too high worsens, has solved the difficult problem of bimetal or many metals difficult processing simultaneously. Meanwhile, the bimetal component with a complex shape can be directly formed without subsequent machining and heat treatment, so that the utilization rate of the material is improved.

Next, each part of the above-described additive manufacturing apparatus in the present exemplary embodiment will be described in more detail with reference to fig. 1.

In one embodiment, the additive manufacturing apparatus is further provided with a powder suction unit 800, which is disposed on the movable powder feeding unit 400, and is used for sucking the powder in the preset selected area. Specifically, the powder suction unit 800 is arranged on the movable powder feeding unit 400, when the movable powder feeding unit 400 works, a layer of powder is firstly laid on the forming platform 120, then the powder suction unit 800 is used for sucking away the powder in the selected area needing accurate powder feeding, and then the movable powder feeding unit 400 is used for laying the required powder.

In one embodiment, as shown in fig. 1, the powder bin group includes three powder bins, including a first powder bin 310, a second powder bin 320 and a third powder bin 330, the first powder bin 310 is disposed at a first side of the forming bin 100 for disposing the first powder, the second powder bin 320 is disposed at a second side of the forming bin 100 for disposing the second powder, and the third powder bin 330 is disposed above the first powder bin 310 or the second powder bin 320 for disposing the third powder.

Specifically, a first filler bin 310 and a second filler bin 320 are respectively disposed at two sides of the forming bin 100, a third filler bin 330 is disposed above the first filler bin 310, and the first filler bin 310, the second filler bin 320 and the third filler bin 330 are respectively filled with a first powder, a second powder and a third powder.

In one embodiment, as shown in fig. 1, a vibration unit 331 is disposed in the third powder bin 330, and is used for discharging the powder from the third powder bin 330 by vibration. Specifically, the vibration unit 331 is disposed in the third powder bin 330, and after the vibration unit 331 vibrates, the third powder is vibrated out of the third powder bin 330, and meanwhile, the discharging amount of the third powder in the third powder bin 330 can be accurately controlled through the vibration unit 331.

In another embodiment, the powder discharge of the third powder bin 330 is controlled by a valve switch. Specifically, a valve is disposed at an outlet of the third powder bin 330, and the outlet of the third powder is controlled by controlling the valve to open and close.

In one embodiment, the movable powder feeding unit 400 is provided with three precise powder bins as shown in fig. 1, including a first precise powder bin 410, a second precise powder bin 420 and a third precise powder bin 430, and the first precise powder bin 410, the second precise powder bin 420 and the third precise powder bin 430 are respectively provided with the first powder, the second powder and the third powder.

In one embodiment, as shown in fig. 1, a forming substrate lifting unit 130 is disposed at the bottom of the forming substrate 110 for adjusting the horizontal height of the forming substrate 110 to adjust the powder spreading thickness, and the control unit 900 controls the forming substrate lifting unit 130, wherein the powder spreading thickness is 0.03mm to 0.1 mm.

Specifically, in the forming chamber 100, the forming substrate 110 is used for disposing the first powder, the second powder, and the third powder, a forming substrate lifting unit 130 is disposed at the bottom of the forming substrate 110 for adjusting the horizontal height of the forming substrate 110, and the disposed powder and the upper surface of the component being printed form a forming platform 120. The powder flowability is reduced by preheating with the electron beam heat source 200, the formed substrate lifting unit 130 descends again to ensure that the first scraper unit 510 and the second scraper unit 520 do not scrape the powder on the forming platform 120 away, then the first scraper unit 510 and the second scraper unit 520 scrape the first powder, the second powder and the third powder to the formed substrate 110, the powder in the selected area is melted and formed, the formed substrate lifting unit 130 adjusts one layer down with each formed layer of the part to lower the height of the formed substrate 110 by one layer until the printing is completed, the powder spreading thickness is 0.03mm to 0.1mm, for example, the powder spreading thickness is 0.1mm, and no specific limitation is made here.

In one embodiment, as shown in fig. 1, the additive manufacturing apparatus further comprises a first scraper unit 510 and a second scraper unit 520; the first doctor unit 510 is disposed between the first hopper 310 and the forming hopper 100, the second doctor unit 520 is disposed between the second hopper 320 and the forming hopper 100, and the control unit 900 controls the first doctor unit 510 and the second doctor unit 520.

Specifically, a first scraper unit 510 is arranged between the forming bin 100 and the first powder bin 310, and a second scraper unit 520 is arranged between the forming bin 100 and the second powder bin 320; when the first scraper unit 510 works, the first scraper unit 510 moves to the first powder bin 310, and scrapes and conveys the first powder in the first powder bin 310 to the forming substrate 110 for powder paving; when the second doctor unit 520 operates, the second doctor unit 520 moves to the second powder bin 320, and scrapes the second powder in the second powder bin 320 to the forming substrate 110 for powder spreading.

In one embodiment, as shown in fig. 1, the additive manufacturing apparatus further includes a first powder falling unit 610 and a second powder falling unit 620, the first powder falling unit 610 is disposed between the forming bin 100 and the first scraper unit 510, the second powder falling unit 620 is disposed between the forming bin 100 and the second scraper unit 520, and the control unit 900 controls the first powder falling unit 610 and the second powder falling unit 620.

Specifically, a first powder falling unit 610 is arranged between the forming bin 100 and the first scraper unit 510, and a second powder falling unit 620 is arranged between the forming bin 100 and the second scraper unit 520. When the first powder dropping unit 610 and the second powder dropping unit 620 are closed, the forming bin 100 and the first powder bin 310 are connected with the second powder bin 320, so that the powder can pass through the upper surfaces of the first powder dropping unit 610 and the second powder dropping unit 620. When the first scraper unit 510 moves, the first powder falling unit 610 is closed, the second powder falling unit 620 is opened, the first scraper unit 510 scrapes and sends the first powder or the third powder to the forming substrate 110, the powder is continuously scraped and sent to the second powder falling unit 620, and the redundant powder falls from the second powder falling unit 620, and meanwhile, the second scraper unit 520 does not move; similarly, when the second scraper unit 520 moves, the second powder falling unit 620 is closed, the first powder falling unit 610 is opened, the second scraper unit 520 scrapes and sends the second powder or the third powder to the forming substrate 110, and then the powder is continuously scraped and sent to the first powder falling unit 610, and the excessive powder falls from the first powder falling unit 610, and meanwhile, the first scraper unit 510 does not move.

In one embodiment, as shown in fig. 1, a first lifting unit 710 is disposed in the first hopper 310, a second lifting unit 720 is disposed in the second hopper 320, and the control unit 900 controls the first hopper 310.

Specifically, a first lifting unit 710 is disposed at the bottom 310 of the first powder bin for adjusting the height of the first powder bin 310, and a second lifting unit 720 is disposed at the bottom 320 of the second powder bin for adjusting the height of the second powder bin 320. The first lifting unit 710 adjusts the height of the first hopper 310, pushes the first powder out of the first hopper 310, and then scrapes the first powder to the forming table 120 by the first scraper unit 510; similarly, the second lifting unit 720 adjusts the height of the second powder bin 320, pushes the second powder out of the second powder bin 320, and then scrapes the second powder to the forming platform 120 by the second scraper unit 520.

In one embodiment, as shown in fig. 3, a powder sieving unit is disposed in each of the first powder falling unit 610 and the second powder falling unit 620, and is used for sieving powder mixed during printing and recycling the powder.

Specifically, as shown in fig. 3, for example, assuming that 7 layers of screens with corresponding diameter meshes are arranged according to different particle size intervals of the powder in the first powder falling unit 610, after the second scraper unit 520 scrapes the mixed powder to the first powder falling unit 610, when the powder in different particle size intervals passes through the screens 1 to 7, the powder with small particle size is sieved out first, and the powder with large particle size is sieved out later; the speed of the powder on the screen is uniform in the screen arranged in the first scheme, the speed of the powder on the screen is high firstly and then low in the screen arranged in the second scheme, and the speed of the powder on the screen is low firstly and then high in the screen arranged in the third scheme.

By the aid of the device, the electron beam is used as an energy source, the advantages of high energy density and high utilization rate of the electron beam are utilized, high density of forming of refractory metals and brittle materials is guaranteed, a forming substrate is preheated by means of the characteristic of rapid scanning of the electron beam, extremely high part forming temperature is guaranteed, the phenomenon that residual stress is too large due to cooling of different materials due to different thermal expansion coefficients is reduced, the number of defects of parts is increased, and deformation and cracking risks are greatly avoided. The clean environment of high vacuum has reduced the impurity content in the printing part, prevents that the fragility problem that leads to because of impurity concentration is too high worsens, has solved the difficult problem of bimetal or many metals difficult processing simultaneously. Meanwhile, the bimetal component with a complex shape can be directly formed, subsequent machining and heat treatment are not needed, the utilization rate of materials is improved, compared with the traditional machining process, the manufacturing period is greatly shortened, and the cost is saved.

The present exemplary embodiment further provides a bi-metal or multi-metal additive manufacturing method applied to the additive manufacturing apparatus according to the above invention, and referring to fig. 2, the method may include: step S101 to step S102

Step S101: acquiring slice data of each layer of a part model to be printed;

specifically, a three-dimensional model is constructed, then the model is sliced into a plurality of cutting layers, and cutting layer data are produced according to the powder proportion of each cutting layer.

Step S102: and according to the slicing data, paving powder by using the powder bin group, and paving powder in the preset selected area by using the movable powder feeding unit 400.

Specifically, when printing is started, the forming substrate 110 is preheated, powder spreading and melting scanning is performed according to the layer cutting data and the scanning path data, and powder spreading is performed using the powder bin group and the movable powder feeding unit 400.

In one embodiment, assuming that the first powder is laid first, when the first powder dropping unit 610 is turned off, the second powder dropping unit 620 is turned on, and the second scraper unit 520 does not move, the first scraper unit 510 scrapes the first powder in the first powder bin 310 to the forming substrate 110, and simultaneously the movable powder feeding unit 400 cooperates to feed the second powder to the selection area; when the second powder is deposited, the second powder dropping unit 620 is turned off, the first powder dropping unit 610 is turned on, and the first blade unit 510 is not moved, and the second blade unit 520 scrapes the second powder in the second powder bin 320 to the forming substrate 110.

In addition, as shown in fig. 4, assuming that the first powder is a1 and the second powder is a2, when the current sliced layer is printed, the ratio of the first powder a1 is greater than or equal to the ratio of the second powder a2, the first powder bin 310, the first scraper unit 510 and the second powder dropping unit 620 are activated to uniformly lay the first powder on the preheated forming substrate 110, and then the second powder is laid in a preset selection area by the movable powder feeding unit 400, and then the sliced layer is subjected to melting scanning; when the proportion of the first powder is smaller than that of the second powder, the second powder bin 320, the second scraper unit 520 and the first powder dropping unit 610 are started to uniformly lay the second powder on the preheated forming substrate 110, and then the movable powder feeding unit 400 is used to lay the first powder in a preset selection area and then to perform melting scanning on the sliced layer.

In one embodiment, as shown with reference to fig. 5, the method further comprises: and (3) performing particle size distribution on the mixed powder during printing according to different particle sizes of the powder.

Specifically, the shape of the metal powder is spherical, and the sphericity is>90% and a mass purity of not less than 99.9%, as shown in FIG. 5, assuming that the particle size of the metal powder is 30 to 180 μm, if necessaryThe granularity calculation interval can be divided into N (N = q (number of grades) × p (number of materials)) equal parts, p = 2-5, and each granularity interval is marked as

Wherein

=150 μm, interval of granularity interval

= 2-10 μm, and the particle diameter interval of A1 metal powder is

The range of the particle size of the A2 metal material powder is

The range of the particle size of the A3 metal material powder is

The bulk density of the powder after the grading is not less than 50% of the theoretical density, and the fluidity is not more than 25s/50g, and specific examples are as follows, for example, two kinds of powder A1 and A2 are available, and the spacing is selected

And =3 μm, before printing, the powder with the granularity of 30-52 μm, 80-102 μm and 130-152 μm of the screening A1 is used as the base powder for printing, the powder with the granularity of 55-77 μm, 105-127 μm and 155-180 μm of the screening A2 is used as the base powder for printing, after the powders are mixed, the two powders A1 and A2 can be distinguished according to a fixed granularity interval, meanwhile, the powder with the granularity of 55-77 μm, 105-127 μm and 155-180 μm of the powder A1 and the powder with the granularity of 30-52 μm, 80-102 μm and 130-152 μm of the powder A2 can also be used as other base powder for printing, and the method does not waste the powder, is beneficial to the recovery of different powders and does not reduce the printing quality of the powder.

In one embodiment, before the movable powder feeding unit 400 spreads the powder, the powder suction unit 800 is used to suck the powder in the preset powder selecting area, the size of the suction force can be controlled by the powder suction unit 800, and the precision of the powder suction selecting area can reach 0.02-0.05 mm.

Specifically, when printing is performed, after a layer of powder is laid, and when the powder needs to be fed by the movable powder feeding unit 400, the powder absorbing unit 800 is used for micro-cleaning the base powder in the area needing to be accurately spread, then the movable powder feeding unit 400 is used for laying the powder, the suction force of the powder absorbing unit 800 can be adjusted according to the actual condition of the sintered powder, wherein the precision of the powder absorbing and selecting area can reach 0.02-0.05 mm, for example, the precision of the powder absorbing and selecting area can reach 0.02mm, but no specific limitation is imposed.

In one embodiment, as shown in fig. 6, when the printing is performed on a transition layer surface, the included angle between two consecutive scans is 45 ° -90 ° in a 200-hour-hand-direction scanning mode, the transition layer surface is preset to be m layers, and each layer needs to be preset to be scanned n times, wherein m = 2-4, and n = 1-3.

Specifically, when the transition layer surface is printed, if the difference between the physical and chemical properties of the first powder and the second powder is large and the first powder and the second powder cannot be metallurgically bonded by an electron beam melting method, the third powder may be a transition element, a mixed powder of the first powder and the second powder, or an alloy powder of the first powder and the second powder. In the transition surface layer, if the proportion of the third powder is greater than or equal to that of the first powder and the second powder, the third powder bin 330, the first precise powder bin 410 and/or the second precise powder bin 420 in the movable powder feeding unit 400 are started to lay powder on the transition surface layer, the third powder is shaken off by the vibration unit 331, then the third powder is scraped to the forming substrate 110 by the first scraper unit 510 or the second scraper unit 520, and then the first powder and the second powder are sent to a designated area by the movable powder feeding unit 400 to be melted; if the third powder ratio is smaller than the first powder and the second powder, the third precise powder bin 430, the first powder bin 310 and/or the second powder bin 320 are activated to lay powder on the transition layer surface, the first scraper unit 510 or the second scraper unit 520 is used to scrape the first powder or the second powder to the forming substrate 110, and then the movable conveying unit is used to convey the first powder or the second powder to the forming substrate 110The powder unit 400 sends the third powder to a designated area. Meanwhile, it is assumed that the number of transition layer layers m =3, the number of scanning times of each layer n =3, and an included angle between two consecutive scanning times is 45 degrees, which is not specifically limited herein, and the scanning paths of n times are respectivelyl1、l2······ln is thatl1、l2、lAnd 3, scanning the electron beam heat source 200 clockwise and scanning twice at 45 degrees, wherein the number of layers and the scanning times are determined according to the solid solution diffusion rate among the materials, and the bonding strength of the bonding position is favorably increased.

By combining the method, the electron beam is used as an energy source, the advantages of high energy density and high utilization rate of the electron beam are utilized, the high density of the formed refractory metals and brittle materials is ensured, the formed substrate is preheated by utilizing the characteristic of fast scanning of the electron beam, the extremely high part forming temperature is ensured, the phenomenon that the residual stress generated by cooling different materials due to different thermal expansion coefficients is too large, the parts generate more defects is favorably reduced, and the risk of deformation and cracking is greatly avoided. The clean environment of high vacuum has reduced the impurity content in the printing part, prevents that the fragility problem that leads to because of impurity concentration is too high worsens, has solved the difficult problem of bimetal or many metals difficult processing simultaneously. The high vacuum clean environment reduces the impurity content in the printed parts, prevents the brittleness problem deterioration caused by the over-high impurity concentration, and also solves the difficult problem of difficult processing of double metals or multiple metals. Meanwhile, the bimetal component with a complex shape can be directly formed, subsequent machining and heat treatment are not needed, the utilization rate of materials is improved, compared with the traditional machining process, the manufacturing period is greatly shortened, and the cost is saved. And multiple multi-layer scanning is adopted at the fusion bonding interface, so that the bonding strength of the bonding position is increased. The invention adopts the optimized powder granularity distribution and recovery technology, and improves the powder additive manufacturing applicability and the printing quality.

It is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," and the like in the foregoing description are used for indicating or indicating the orientation or positional relationship illustrated in the drawings, merely for the convenience of describing the disclosed embodiments and for simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and therefore should not be considered limiting of the disclosed embodiments.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of the present disclosure, "a plurality" means two or more unless specifically limited otherwise.

In the embodiments of the present disclosure, unless otherwise specifically stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly, e.g., as meaning fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meaning of the above terms in the present disclosure can be understood by those of ordinary skill in the art as appropriate.

In the embodiments of the present disclosure, unless otherwise expressly specified or limited, the first feature "on" or "under" the second feature may comprise the first and second features being in direct contact, or may comprise the first and second features being in contact, not directly, but via another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

Claims

1. A method of additive manufacturing, comprising:

acquiring slice data of each layer of a part model to be printed;

according to the slicing data, powder is paved on a forming substrate by using a powder bin group, powder is paved on the forming substrate by using a movable powder feeding unit and is paved in a preset selection area, and the powder is preheated and melted by using an electron beam heat source;

during printing, the mixed powder falls into a powder falling unit, and the powder is distinguished according to a fixed particle size interval through a powder screening unit in the powder falling unit;

the powder is distributed according to different particle sizes before printing, and after printing, the powder with different particle size intervals is sieved out firstly when passing through a screen mesh, and is sieved out after the powder with large particle size;

the method employs an additive manufacturing apparatus comprising:

the forming substrate is arranged in a forming bin, and the inside of the forming bin is in a vacuum environment;

the electron beam heat source is arranged above the forming bin;

the powder bin group at least comprises a first powder bin and a second powder bin, the first powder bin is arranged on the first side of the forming bin and used for arranging first powder, and the second powder bin is arranged on the second side of the forming bin and used for arranging second powder;

the powder falling unit comprises a first powder falling unit and a second powder falling unit, the first powder falling unit is arranged between the forming bin and the first powder bin, and the second powder falling unit is arranged between the forming bin and the second powder bin;

the powder screening unit is arranged in the first powder falling unit and the second powder falling unit, comprises a screen, is provided with a screen with meshes with corresponding diameters according to different particle size intervals of the powder, is obliquely arranged, and is used for screening the mixed powder during printing and recycling the powder;

the powder feeding device also comprises a control unit for controlling the electron beam heat source, the powder bin group and the movable powder feeding unit.

2. The additive manufacturing method according to claim 1, wherein before the movable powder feeding unit spreads the powder, the powder in a preset selection area is sucked away by using a powder sucking unit, the size of the suction force can be controlled by the powder sucking unit, and the precision of the powder sucking selection area can reach 0.02-0.05 mm.

3. The additive manufacturing method according to claim 1, wherein when printing to the transition layer surface, the electron beam heat source turns clockwise to scan, and the included angle between two consecutive scans is 45 ° to 90 °, the transition layer surface is preset to m layers, and each layer needs to be preset n times, where m is 2 to 4, and n is 1 to 3.

4. The additive manufacturing method of claim 1, further comprising:

and laying third powder by using a third powder bin which is arranged above the first powder bin or the second powder bin.

5. The additive manufacturing method according to claim 4, wherein the third powder bin discharges powder by vibration, and a vibration unit is arranged in the third powder bin.

6. The additive manufacturing method according to claim 1, wherein a horizontal height of the forming substrate is adjusted to adjust a powder thickness, the powder thickness being 0.03mm to 0.1 mm.