Patent Publication Number: US-11040400-B2

Title: Additive manufacturing facility with successive nested confinement chambers

Description:
BACKGROUND 
     The invention relates to the field of powder-based additive manufacturing by sintering or melting the grains of said powder using an energy beam with electromagnetic radiation, such as a laser beam, and/or a particle beam, such as an electron beam. 
     More specifically, the invention relates to the containment of an additive manufacturing facility comprising a plurality of additive manufacturing machines and the contained transport of the additive manufacturing trays within such a facility. 
     During the implementation of an additive manufacturing process inside the manufacturing chamber of an additive manufacturing machine, a first layer of powder is deposited on an additive manufacturing tray mounted slidingly inside a manufacturing sleeve held in position inside the manufacturing chamber. Then, this first layer of powder is consolidated in a predetermined pattern using one of the abovementioned energy beams. Next, the manufacturing tray is lowered inside the manufacturing sleeve so as to allow the deposition and consolidation of a second layer of powder. Finally, the steps of lowering the tray and then depositing and consolidating the layers of powder follow one another until the deposition and consolidation of the last layer of powder required for the manufacture of the parts to be produced. 
     On completion of the additive manufacturing cycle, the manufactured parts are connected to the additive manufacturing tray by their base, and the manufactured parts are buried in a large amount of unconsolidated powder. 
     To retrieve the manufactured parts, it is necessary to extract the additive manufacturing tray from the manufacturing chamber of the machine. Preferably, the additive manufacturing tray and the manufactured parts are extracted from the manufacturing chamber with the aid of a container which is positioned under the manufacturing sleeve. Advantageously, said container may also be used to recover and transport the unconsolidated powder which surrounds the manufactured parts. 
     In order to implement a new additive manufacturing cycle, a new, clean tray must be inserted and put in place in the manufacturing chamber of the additive manufacturing machine. 
     When using a plurality of additive manufacturing machines for the production of parts on an industrial scale, the operations of extraction and insertion of additive manufacturing trays cannot be carried out manually by operators. 
     First, the operators would be repeatedly exposed to the toxicity of certain components of the additive manufacturing powders. Second, when performed manually, these operations would take too much time. 
     Thus, as disclosed for example in U.S. Pat. No. 6,824,714, chain conveyor means may be used to convey, in an automated manner, empty container/tray assemblies to the manufacturing chamber of an additive manufacturing machine and to extract from said chamber the container/tray assemblies used with the manufactured parts and the unconsolidated powder surrounding them. 
     According to a first disadvantage of the solution described in document U.S. Pat. No. 6,824,714, the container/tray assemblies filled with unconsolidated powder are extracted from the machine and conveyed without protection or means to prevent unconsolidated powder grains from spreading in the facility. 
     Given the toxicity of certain components of additive manufacturing powders used industrially, especially for the manufacture of metal parts, the solution disclosed in U.S. Pat. No. 6,824,714 presents environmental hazards and health and safety risks for people moving around in the facility, even if they wear the appropriate protective equipment, such as overalls, goggles and masks. 
     Lastly, according to another disadvantage of the solution described in U.S. Pat. No. 6,824,714, the automated means for inserting and extracting the additive manufacturing container/tray assemblies do not make it possible to preserve the inert or controlled atmosphere required for the additive manufacturing process implemented inside the manufacturing chamber of the additive manufacturing machine. 
     Therefore, with the automated solution disclosed in U.S. Pat. No. 6,824,714, it is necessary to provide a step of inerting or conditioning the air present inside the manufacturing chamber after each step of extraction of an additive manufacturing container/tray assembly. From an industrial point of view, this air conditioning or inerting step reduces the amount of time the additive manufacturing machines are effectively in use and therefore the production capacities. 
     Lastly, to comply with certain rules for protection of the environment and the health of persons working in additive manufacturing facilities, there is also a need to improve the sanitary conditions of use of additive manufacturing machines. 
     SUMMARY 
     Thus, the present invention aims to overcome at least one of the disadvantages identified in the prior art and to meet the abovementioned industrial needs. 
     To this end, the subject matter of the invention is an additive manufacturing facility operating in an automated and contained manner. 
     According to the invention, said facility comprises a containment chamber inside which a plurality of additive manufacturing machines is installed, each machine comprising a manufacturing chamber and making it possible to manufacture parts in an automated and contained manner inside said chamber. 
     Furthermore, said facility comprises, inside the containment chamber, a supply device and a supply circuit for supplying, in an automated and contained manner, the various machines of the facility with an additive manufacturing powder ready to be used in additive manufacturing. 
     Then, inside the containment chamber, said facility comprises a conveying device for conveying additive manufacturing container/tray assemblies, comprising at least one conveying chamber circulating between the various machines in order to supply, in an automated and contained manner, the various machines of the facility with clean trays and to retrieve, in an automated and contained manner, the trays that have been used by these machines. 
     Lastly, inside the containment chamber, said facility further comprises a cleaning device comprising at least one cleaning chamber, for cleaning, in an automated and contained manner, the additive manufacturing trays in said cleaning chamber. 
     By virtue of the complete automation of the facility according to the invention, it is possible to control the operation of the facility from outside the containment chamber, and thus limit the human presence in the facility to maintenance and repair procedures only. 
     Advantageously, by transporting, in a contained manner, the additive manufacturing container/tray assemblies between the various additive manufacturing machines and the cleaning device, contamination of the facility and its surroundings with particles that may be toxic to humans is prevented. 
     According to one significant advantage, the contained transport of the additive manufacturing container/tray assemblies makes it possible to envisage transport under a controlled or inert atmosphere in order to avoid re-conditioning of the air inside the manufacturing chamber of an additive manufacturing machine after each step of extraction and insertion of an additive manufacturing container/tray assembly from/into said chamber. 
     The invention also provides a method for the containment of an additive manufacturing facility according to the invention. 
     According to this method, the air inside the containment chamber is kept at a pressure below the air outside the containment chamber. Thus, the containment provided by the leaktightness of the containment chamber is improved by the differences in pressure between the inside and the outside of the chamber. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the invention will become apparent from the description which follows. This description, provided by way of non-limiting example, refers to the attached drawings, in which: 
         FIG. 1  is a schematic aerial view of an additive manufacturing facility according to the invention, 
         FIG. 2  is a schematic side view of an additive manufacturing facility according to the invention, 
         FIG. 3  is a schematic perspective view of a conveying device for conveying additive manufacturing container/tray assemblies according to the invention, 
         FIG. 4  is a view in detail of  FIG. 1 , 
         FIG. 5  is a schematic sectional view of a conveying device for conveying additive manufacturing container/tray assemblies according to the invention, and 
         FIG. 6  is a schematic sectional view showing the extraction or insertion of an additive manufacturing container/tray assembly from/into the manufacturing chamber of an additive manufacturing machine with a conveying device according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIG. 1 , the invention relates to an additive manufacturing facility comprising a plurality of additive manufacturing machines M 1 , M 2 , M 3 , M 4  installed inside a containment chamber  10  of the facility. 
     Containment chamber  10  means a sealed chamber that prevents the circulation of air present inside the chamber to the outside of the chamber. 
     As can be seen in  FIG. 6 , each machine M 1 , M 2 , M 3 , M 4  comprises a manufacturing chamber  12  and is used to manufacture parts in an automated and contained manner inside said chamber  12 . The manufacture is said to be contained because the manufacturing chamber  12  may be closed in a sealed manner, in such a way as to prevent the circulation of air from inside said manufacturing chamber  12  to the outside of said chamber, i.e. to the containment chamber  10  of the facility. 
     Advantageously, each machine M 1 , M 2 , M 3 , M 4  may comprise several, and preferably two, work zones inside its manufacturing chamber  12 . Thus, each machine makes it possible to manufacture parts on several additive manufacturing trays simultaneously. 
     As shown in  FIG. 4 , the chamber  12  of each machine M 1 , M 2 , M 3 , M 4  may comprise as many entry/exit airlocks  14  for additive manufacturing container/tray assemblies as there are work zones  16 , the container/tray assemblies entering and exiting each work zone  16  via an entry/exit airlock  14  dedicated to said work zone. 
     In order to supply, in an automated and contained manner, the various machines M 1 , M 2 , M 3 , M 4  of the facility with an additive manufacturing powder that is ready for use in additive manufacturing, the facility includes, inside the containment chamber  10 , a powder supply device  18  and supply circuit  20 . Said supply circuit  20  connects the supply device  18  to the various machines M 1 , M 2 , M 3 , M 4  of the facility. Advantageously, the supply device  18  is also used to prepare the powder before dispensing it to the machines, said preparation comprising, for example, steps of drying and sieving the powder. 
     Since the supply device  18  comprises numerous conduits connecting processing, metering and powder flow control devices, said supply device  18  comprises numerous junctions through which grains of powder can escape. Since some additive manufacturing powders may include toxic compounds, the invention provides for isolation of the supply device  18  from the rest of the facility. To this end, the supply device  18  is contained within a protective chamber  22  provided inside the containment chamber  10  of the facility, the conduit or conduits  24  of the supply circuit  20  passing through a wall  26  of said protective chamber  22  in a sealed manner. In order to allow the conduit  24  to pass through the wall  26  in a sealed manner, an opening is for example made in said wall  26  and sealing means are provided at said opening between said wall  26  and said conduit  24 . 
     Again with a view to limiting powder leakage in the containment chamber  10  of the facility, the supply circuit  20  conveys the powder, by suction from the supply device  18 , to the machines M 1 , M 2 , M 3 , M 4  of the facility. 
     In order to avoid operators having to enter the containment chamber  10  or the protective chamber  22  of the supply device  18  to replenish it with powder, provision is made to replenish said supply device  18  from outside the protective chamber  22  and from outside the containment chamber  10  of the facility. To this end, a replenishment room  28  is provided outside the containment chamber  10 , a replenishment circuit  30  serving to connect a replenishment container  32  located in said replenishment room  28  to the supply device  18 . Like the conduit or conduits  24  of the supply circuit  20 , the conduit or conduits  36  of said replenishment circuit  30  pass through the wall or walls  34  of the containment chamber  10  and the protective chamber  22  in a sealed manner. 
     Advantageously, a powder recovery circuit  38  connects each machine M 1 , M 2 , M 3 , M 4  of the facility to the supply device  18  so as to recycle and reuse the excess additive manufacturing powder deposited in each machine of the facility. Said recovery circuit  38  conveys the powder, by suction from the machines M 1 , M 2 , M 3 , M 4 , to the supply device  18 , and the conduit or conduits  40  of the recovery circuit  38  pass through the wall  26  of the protective chamber  22  in a sealed manner. 
     Again in the containment chamber  10 , and for complete automation of the facility, said facility also includes a conveying device  42  for conveying additive manufacturing container/tray assemblies C. 
     Additive manufacturing container/tray assembly C means the assembly made up of an additive manufacturing tray and an additive manufacturing container. The container takes the form of a wall surrounding the tray and it serves to transport the tray with the manufactured parts and the unconsolidated powder surrounding them. 
     In order to convey these additive manufacturing container/tray assemblies C, the conveying device  42  comprises at least one conveying chamber  44  circulating between the various machines M 1 , M 2 , M 3 , M 4 . Said conveying device  42  makes it possible to supply, in an automated and contained manner, the various machines M 1 , M 2 , M 3 , M 4  of the facility with clean trays P and to retrieve, in an automated and contained manner, the trays P that have been used by these machines M 1 , M 2 , M 3 , M 4 , as well as the manufactured parts. 
     As a variant or where specifically required, the conveying device  42  also makes it possible to transport, in a contained manner, trays P alone, that is to say without containers, but with or without the manufactured parts. In the case where the conveying device  42  is used to transport trays without containers but with the manufactured parts, the machines M 1 , M 2 , M 3 , M 4  are preferably equipped with means for recovering the unconsolidated powder surrounding the manufactured parts at the end of an additive manufacturing cycle. 
     In more detail, the conveying device  42  takes the form of a circulation path  46  extending within the containment chamber  10  of the facility and on the floor  47  of said chamber  10 , the conveying chamber or chambers  44  being mounted on a trolley  48  designed to run on said path  46 , as shown in  FIGS. 2 to 6 . 
     Preferably, the circulation path  46  is rectilinear and the various machines M 1 , M 2 , M 3 , M 4  of the facility are distributed on either side of a first section T 1  of said circulation path  46 . Again preferably, said first section T 1  is located at a first end E 1  of the circulation path  46  of the conveying device  42 . 
     Again in the containment chamber  10 , and for complete automation of the facility, the facility includes a cleaning device  50  comprising at least one cleaning chamber  52  for cleaning, in an automated and contained manner, the additive manufacturing trays P, and also the manufactured parts, in said cleaning chamber  52 . Advantageously, only the trays P and the manufactured parts require cleaning because they are to be extracted from the containment chamber  10 , unlike the containers, which remain inside the containment chamber  10 . 
     In a preferred variant, the cleaning device  50  comprises a first dry cleaning chamber  52  and a second wet cleaning chamber  54 , and a conveyor  56  for transporting the trays P from one chamber to another. Advantageously, the wet cleaning chamber  54  is located near an entry/exit airlock  58  for inserting the additive manufacturing trays P into the containment chamber  10  and extracting the trays P from the containment chamber  10 , a second conveyor  60  for conveying trays P being provided between said wet cleaning chamber  54  and said airlock  58 . 
     In a preferred embodiment of the facility, the cleaning device  50  and the entry/exit airlock  58  for the trays P are located at the second end E 2  of the rectilinear circulation path  46  of the conveying device  42 . 
     In order to optimize the containment of the container/tray assemblies C in the various chambers of the various machines and devices of the facility, the facility includes a device  62  for controlling the air pressure inside the containment chamber  10  of the facility, devices  64  for controlling the air pressure inside the manufacturing chambers  12  of the additive manufacturing machines M 1 , M 2 , M 3 , M 4 , a device  66  for controlling the air pressure inside each conveying chamber  44  of the conveying device  42 , and a device  68  for controlling the air pressure inside at least one cleaning chamber  52 ,  54  of the cleaning device  50 . With these various devices  62 ,  64 ,  66  and  68 , it is possible to keep the air in the chambers  12 ,  44 ,  52  and  54  at pressures below or equal to the air pressure in the containment chamber  10 . Any leakage of toxic powder grains from these chambers  12 ,  44 ,  52  and  54  to the containment chamber  10  is thus limited. 
     Advantageously, the device  62  also makes it possible to treat the air before introducing it inside the containment chamber  10  of the facility. For example, the device  62  makes it possible to filter and control the temperature and humidity of the air taken from outside the containment chamber  10  before introducing it into said chamber. 
     In order to be able to manage the inerting of the manufacturing chambers  12  and conveying chambers  44 , the devices  64  may also be used to control the gaseous composition of the air introduced into the manufacturing chambers  12  of the additive manufacturing machines M 1 , M 2 , M 3 , M 4 , and the device  66  may also be used to control the gaseous composition of the air introduced into each conveying chamber  44  of the conveying device  42 . More specifically, the devices  64  and  66  may be used to control the level of oxygen in the air introduced into the chambers to which these devices are connected. Providing for inerting of each conveying chamber  44  dispenses with the need for the machines M 1 , M 2 , M 3 , M 4  to be equipped with an inerting airlock and avoids re-inerting the air present in each manufacturing chamber after each entry/exit of a container/tray assembly C. Advantageously, the devices  64  and  66  may also be used to manage, from outside of the containment chamber  10 , the de-inerting of the chambers to which they are connected. 
     Preferably, all of these various devices  62 ,  64 ,  66  and  68  are located outside the containment chamber  10  of the facility. Therefore, these devices do not clutter the working volume of the containment chamber  10  and it is possible to intervene on these devices without having to enter the containment chamber  10  with the required protective equipment. In addition, because they are located outside the containment chamber  10  of the facility, these various devices  62 ,  64 ,  66  and  68  do not require regular decontamination. 
     In order to promote the evacuation of grains or particles of high density additive manufacturing powder, a downward air flow is provided in the containment chamber  10  of the facility. To this end, the ceiling  70  of the containment chamber  10  is equipped with at least one ventilator  72  through which air is introduced into the containment chamber, and at least one air extractor  74  through which air is extracted from the containment chamber  10  is provided level with the floor  47  of the containment chamber. In more detail, the ventilator  72 , for example taking the form of a ventilation rail, is connected to the device  62  for controlling the pressure and the composition of the air inside the containment chamber  10  of the facility, and each air extractor  74  is connected to a filtration device  76  for filtering the air before discharging it out of the containment chamber  10 . 
     In order to control their operation from outside the containment chamber  10  of the facility, each additive manufacturing machine M 1 , M 2 , M 3 , M 4 , along with the cleaning device  50  and the conveying device  42 , comprise a management interface  78  located outside the containment chamber  10  of the facility. Preferably, a single management interface  78  is shared by the various machines and the various devices mentioned above. As shown in  FIG. 1 , said shared management interface  78  may be installed in a supervision booth  80  located outside the containment chamber  10 . 
     In order to limit the surfaces on which grains of unconsolidated powder may be deposited above the floor  47  of the containment chamber  10 , and as the management interface  78  and the means for supplying air, such as the devices  64 ,  66  and  68 , and/or electrical power and/or pneumatic power to the additive manufacturing machines M 1 , M 2 , M 3 , M 4 , the cleaning device  50  and the conveying device  42 , are located outside the containment chamber  10  of the facility, the computer links, for example wiring, connecting the additive manufacturing machines M 1 , M 2 , M 3 , M 4 , the cleaning device  50  and the conveying device  42  to their management interface  78 , and their connections, for example conduits and cables  81 , to their means for supplying air and/or electrical power and/or pneumatic power, extend between the top of these machines and these devices and the ceiling  70  of the containment chamber. As the conveying device  42  is mobile, it is connected to its management interface  78  and to its supply means via a drag chain  82 . 
     In order to regulate the flows of container/tray assemblies C between the machines M 1 , M 2 , M 3 , M 4  and the cleaning device  50 , two devices  84  and  86  for storing container/tray assemblies C are provided. The chambers of said storage devices are designed to be placed in communication with the conveying chamber or chambers  44  of the conveying device  42 . In order to avoid contamination of the clean trays P, one of these devices  84  is dedicated to the storage of container/tray assemblies C containing clean trays P, and the other device  86  is dedicated to the storage of container/tray assemblies C containing trays P to be cleaned. Advantageously, it may also be envisaged inerting the storage chambers of these devices  84 ,  86  and controlling the air pressure inside these chambers. Preferably, these two storage devices  84  and  86  are located towards the centre of the circulation path  46  of the conveying device  42 , between the machines M 1 , M 2 , M 3 , M 4  and the cleaning device  50 . 
     In order to allow manual extraction of a damaged or defective tray P or container/tray assembly C, a maintenance airlock  88  is provided along the circulation path  46  of the conveying device  42 . The chamber of said maintenance airlock  88  is designed to be placed in communication with the conveying chamber or chambers  44  of the conveying device  42 . Preferably, said maintenance airlock  88  is located at the second end E 2  of the circulation path  46  of the conveying device  42 . 
     Again at the second end E 2  of the circulation path  46  of the conveying device  42 , and at the end of said path  46 , a maintenance zone  90  is provided for carrying out various maintenance procedures on the trolley  48  of the conveying device  42 , such as the replacement of a conveying chamber  44 , for example. 
     In addition to the various containment chambers and the various air flow and treatment devices that have just been described, the invention also provides a method for improving the containment of the container/tray assemblies C, and hence of the trays P, transported and used in the various chambers of the various devices and machines of the facility. 
     Firstly, and in order to protect the environment outside the facility, such as the other facilities of a plant, according to the containment method, the air inside the containment chamber  10  is kept at a pressure below the air outside the containment chamber. Any leakage of additive manufacturing powder grains to the outside of the facility is thus prevented. 
     Then, as each conveying chamber  44  is designed to be placed in communication with the manufacturing chambers  12  of the various machines M 1 , M 2 , M 3 , M 4 , according to the containment method, the air pressure inside each conveying chamber  44  is substantially equal to the air pressure inside the manufacturing chamber  12  of each additive manufacturing machine M 1 , M 2 , M 3 , M 4 . 
     In order to avoid re-inerting of the manufacturing chamber  12  of an additive manufacturing machine M 1 , M 2 , M 3 , M 4  after each extraction and insertion of an additive manufacturing container/tray assembly C, also according to the containment method, the composition of the air inside each conveying chamber  44  is kept substantially identical to the composition of the air inside the manufacturing chamber  12  of each additive manufacturing machine M 1 , M 2 , M 3 , M 4 , particularly with regard to the proportion of oxygen and inert gas, such as nitrogen, in said air. 
     In order to optimize the containment of the dry cleaning chamber  52  of the cleaning device  50 , according to the containment method, the air pressure inside the dry cleaning chamber  52  is kept below the air pressure maintained inside the containment chamber  10  of the facility. 
     Lastly, and in order to optimize the containment of the supply device  18  in its protective chamber  22  provided inside the containment chamber  10  of the facility, according to the containment method, the air pressure inside the protective chamber  22  is kept below the air pressure maintained inside the containment chamber  10 . 
     In parallel with the complete automation of the additive manufacturing facility and the containment of the container/tray assemblies C in various chambers, the invention also relates to a conveying device  42  for conveying said additive manufacturing container/tray assemblies C. 
     As shown in  FIGS. 3 to 6 , the conveying device  42  comprises at least two conveying chambers  44  for conveying an additive manufacturing container/tray assembly C. Each conveying chamber  44  comprises at least one opening  92  for the entry/exit of an additive manufacturing container/tray assembly C, and each opening  92  is provided with a door  94  for closing the conveying chamber  44  in a sealed manner. 
     As they are associated with the trolley  48  and with the circulation path  46  of the conveying device  42 , the two conveying chambers  44  may be used to transport additive manufacturing container/tray assemblies C, and hence additive manufacturing trays P, in a contained and automated manner between the various machines M 1 , M 2 , M 3 , M 4  and the various devices  50 ,  84 ,  86 ,  88  of the facility. Moreover, by transporting the clean trays P separately from those to be cleaned, the two conveying chambers  44  make it possible to preserve the cleanliness of the clean trays P until they are put in place and used within the manufacturing chamber  12  of an additive manufacturing machine. 
     To ensure optimum sealing between a conveying chamber  44  and the manufacturing chamber  12  of a machine M 1 , M 2 , M 3 , M 4  during the transfer of a container/tray assembly C between these two chambers, each wall  96  of a conveying chamber provided with an opening  92  for the entry/exit of an additive manufacturing container/tray assembly C takes the form of a double wall comprising an inner wall  98  and an outer wall  100 , each traversed by an opening  92 ,  102  for the entry/exit of an additive manufacturing container/tray assembly C, the opening  92  in the inner wall  98  being equipped with a door  94  for closing said inner wall  98 , and hence the conveying chamber  44 , in a sealed manner, while the opening  102  in the outer wall  100  is equipped with a peripheral seal  104 . Preferably, a peripheral seal  105  is also provided between the door  94  and the inner wall  98 . In order to achieve sealing between a conveying chamber  44  and the manufacturing chamber  12  of an additive manufacturing machine M 1 , M 2 , M 3 , M 4 , the opening  102  preferably extends over the entire surface of the outer wall  100 . 
     Ideally, and as shown in  FIG. 6 , the wall  106  of a manufacturing chamber  12  designed to be placed in contact with the wall  96  of a conveying chamber  44  also takes the form of a double wall with an inner wall  108  and an outer wall  112 . The inner wall  108  comprises an opening  109  closed by a door  110 , a peripheral seal  115  being provided between the door  110  and the inner wall  108 , and an outer wall  112  with an opening  113  equipped with a peripheral seal  114 . 
     Advantageously, each conveying chamber  44  of the conveying device  42  is equipped with an actuator  116 , such as a rack system, for moving said conveying chamber  44  laterally relative to the trolley  48 . Thus, during the transfer of a container/tray assembly C between a conveying chamber  44  and a manufacturing chamber  12 , the wall  96  of the conveying chamber  44  is pressed against the wall  106  of the manufacturing chamber  12 , and the seals  104 ,  114  of the outer walls  100 ,  112  are compressed against one another so as to seal the communication between these two chambers. 
     To save space and to facilitate bringing the conveying chambers  44  alongside the manufacturing chambers  12 , the doors  94  of the conveying chambers  44  and the doors  110  of the manufacturing chambers  12  are sliding. 
     In one embodiment of the conveying device  42  optimized vis-à-vis the rectilinear circulation path  46  and the linear arrangement of the facility, each conveying chamber  44  comprises at least two opposite side walls  96 D,  96 G, and each of these opposite side walls  96 D,  96 G comprises an opening  92  for the entry/exit of an additive manufacturing container/tray assembly C, provided with a door  94  for closing the conveying chamber  44  in a sealed manner. Thus, the conveying chambers  44  make it possible to bring container/tray assemblies C to machines M 1 , M 2 , M 3 , M 4  and to various devices  50 ,  84 ,  86 ,  88  arranged on either side of the circulation path  46 . 
     Again according to an embodiment of the conveying device  42  optimized vis-à-vis the rectilinear circulation path  46  and the linear arrangement of the facility, as the conveying device  42  comprises a trolley  48  on which the conveying chambers  44  are mounted, the conveying chambers  44  are juxtaposed on the trolley  48  in such a way that each opening  92  in a conveying chamber  44  is juxtaposed with the opening  92  in another conveying chamber. 
     As the trolley  48  extends in a longitudinal direction D 48  parallel to the direction D 46  of the circulation path  46  on which it travels, the conveying chambers  44  are open in a transverse direction DT perpendicular to the longitudinal direction D 48  of the trolley  48 , and preferably on either side of said longitudinal direction D 48 . Moreover, when an actuator  116  moves a conveying chamber  44  laterally relative to the trolley  48 , it moves it in said transverse direction DT. 
     In addition to the actuator  116  for moving a conveying chamber  44  transversely, each conveying chamber  44  comprises an internal conveyor  118  for moving an additive manufacturing container/tray assembly C or tray P in translation through each opening  92  in said chamber. More precisely, said internal conveyor  118  makes it possible to move a container/tray assembly C or tray P in the transverse direction DT perpendicular to the longitudinal direction D 48  of the trolley  48 . 
     For autonomous movements of the trolley  48  along the circulation path  46 , at least one axle  120  of said trolley  48  is motorized. 
     Advantageously, the conveying device  42  and its conveying chambers  44  may be used to transport trays P alone or with the manufactured parts. 
     From a more general point of view, the invention also relates to a method for conveying an additive manufacturing container/tray assembly C or trays P within an additive manufacturing facility comprising a plurality of additive manufacturing machines M 1 , M 2 , M 3 , M 4 . 
     In accordance with the invention, according to said conveying method, the additive manufacturing container/tray assemblies C or trays P are transported in an automated and contained manner within said facility, i.e. within the containment chamber  10  of said facility, between the various machines M 1 , M 2 , M 3 , M 4  and the various devices  50 ,  84 ,  86 ,  88  present within said chamber. 
     Advantageously, also according to said conveying method, the additive manufacturing container/tray assemblies C or trays P are transported in an automated and contained manner in a controlled atmosphere within said facility, in particular by controlling the proportion of oxygen and inert gas, such as nitrogen, in the air present inside the conveying chambers  44 , for example by means of the device  66  and the connections  81 ,  82 . 
     Lastly, and in particular by virtue of the presence of two conveying chambers  44 , according to the method, the clean trays P are conveyed in a conveying chamber other than the conveying chamber used to convey the trays P that have been used by the additive manufacturing machines M 1 , M 2 , M 3 , M 4 . Preferably, one conveying chamber  44  is used for transporting the clean trays P, and the other chamber  44  of the conveying device  42  is used for transporting the trays P that have been used in additive manufacturing. 
     By completely automating the transport of the additive manufacturing container/tray assemblies C or trays P within the facility and by virtue of the presence of the storage devices  84  and  86 , the time for which the additive manufacturing machines M 1 , M 2 , M 3 , M 4  are effectively in use is maximized. Likewise, because the cleaning of the trays P and the supplying with powder are done externally and mutually, the time for which the additive manufacturing machines M 1 , M 2 , M 3 , M 4  are effectively in use is maximized, in particular in comparison with prior art machines incorporating internal means for cleaning the trays and recycling powder.