Patent Publication Number: US-2021162507-A1

Title: Inertable container for transporting an additive manufacturing powder

Description:
The invention is in the field of powder based additive manufacturing by fusing grains of this powder using one or more power sources, such as one or more laser beams and/or one or more electron beams. 
     More specifically, the invention is in the field of additive manufacturing by depositing a powder bed or by powder spraying. 
     The aim of the invention is to facilitate the transportation and the storage of several tens of litres of additive manufacturing powder, while preserving the qualities of the powder. The invention also aims to facilitate the supply of powder to various additive manufacturing machines or other devices that are useful for additive manufacturing, such as powder sieving or drying devices. The invention also aims to facilitate the recovery of powder from various additive manufacturing machines or from other devices that are useful for additive manufacturing, such as powder sieving or drying devices, or devices for cleaning manufactured parts and manufacturing platforms. Finally, the invention also aims to facilitate the packaging or repackaging of batches of new or recycled powder. 
     In the field of additive manufacturing by depositing a powder bed or by powder spraying, the quality of the manufactured parts is directly associated with the quality of the additive manufacturing powder that is used. Therefore, if the quality of the powder is degraded during its transportation, its storage or its transferral to an additive manufacturing machine or to another device, the parts manufactured with this powder will offer worse performance or could even have faults causing these parts to be scrapped. 
     For example, the chemical composition of an additive manufacturing powder can evolve by physicochemical reaction, such as, for example, by oxidation, by adsorption or by absorption, in contact with the water vapour, the oxygen and/or the nitrogen contained in the air present in the workshop where the powder is used, and this evolution can cause a reduction in the mechanical resistance of the manufactured parts or a reduction in the corrosion resistance of the manufactured parts. 
     At the same time, and due to some toxic chemical compounds that they can contain or due to risks of fire or explosion associated with their oxygen reactivity, some additive manufacturing powders can also have health, hygiene or safety risks in relation to the personnel present in the workshops where these powders are handled and used. 
     Therefore, both in order to maintain their quality and the health and safety of personnel, additive manufacturing powders generally need to be transported, stored and transferred in sealed containers or in closed circuits, while avoiding exposing these powders to the air present in the premises where these powders are used. 
     Currently, the additive manufacturing powders are supplied in pots that are sealed and only contain a few litres of powder in an inert gas. On the one hand, several pots are required to supply an additive manufacturing machine for a complete production cycle. Furthermore, these pots do not allow storage that is sufficiently hermetically sealed against the outside air and the water vapour contained in this outside air over time. Finally, once opened, these pots cannot be reused to re-store the powder in an inert atmosphere. 
     Therefore, a requirement exists for being able to transport several tens of litres of additive manufacturing powder with a single container, which can be reused and is able to contain the powder in a protected atmosphere and in a manner that is hermetically sealed against the outside air and the water vapour contained in this outside air over time. 
     Finally, the additive manufacturing powders are fluid and non-attaching products and a requirement exists for facilitating the handling of these powders, while maintaining the quality of the powders and the health and safety of personnel, for example, by limiting the risks of fire and explosion during the transportation or the transferral of oxygen reactive powders. 
     The aim of the present invention is to provide a solution to the aforementioned requirements. 
     To this end, the aim of the invention is an inertable container for transporting an additive manufacturing powder, the container comprising an inertable volume and a main opening granting access to the inside of this inertable volume, the inertable volume comprising an upper portion and a lower portion, the main opening being located in the lower portion of the inertable volume, and the section of the inertable volume increasing gradually over at least part of the height of this inertable volume and from the lower portion towards the upper portion of the inertable volume. 
     According to the invention, the main opening is equipped with a passive half-valve allowing this main opening to be closed in such a way as to be sealed in an airtight and humidity-proof manner, and the container comprises at least two inerting tappings, at least one first upper tapping granting access to the upper portion of the inertable volume and at least one second lower tapping granting access to the lower portion of the inertable volume. 
     By virtue of the passive half-valve, the container allows the powder to be contained in a protected atmosphere and so as to be hermetically sealed against the outside air and the water vapour contained in this outside air over time and, by virtue of the inerting tappings and of the half-valve, the container can be refilled with an inert gas with a view to being used again with a new batch of product. 
     Furthermore, when the inerting tappings are connected to an inert gas supply circuit, these tappings can be used to keep the pressure and the level of inert gas in the container at constant values, thus allowing any micro-leaks to be alleviated and the quality of the powder contained in this container to be guaranteed over time. 
    
    
     
       Further features and advantages of the invention will become apparent from the following description. This description, which is provided by way of a non-limiting example, refers to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a container according to the invention in a first embodiment; 
         FIG. 2  is a section view along a median transverse plane of a container according to the invention in a first embodiment; 
         FIG. 3  is a perspective view of a container according to the invention in a second embodiment; and 
         FIGS. 4A and 4B  are side views of a container according to the invention in a second embodiment. 
     
    
    
     The invention relates to an inertable container  10  for transporting an additive manufacturing powder as shown in  FIGS. 1 to 4B . 
     According to the invention, an additive manufacturing powder is understood to be a powder having grains with a largest grain size that is less than or equal to five hundred micrometres. 
     In an application that is particularly targeted by the present invention, the grains of this powder are likely to be altered through contact with the air present in the premises where this powder is used or through contact with the humidity of this air. 
     For example, the powders intended to be transported or stored with an inertable container according to the invention are metal powders comprising at least one or more metals that can oxidize in contact with the oxygen or the nitrogen contained in the air present in the premises where these powders are used. 
     With a view to transporting and storing such an additive manufacturing powder, the container  10  comprises an inertable volume  12  and a main opening  14  granting access to the inside of this inertable volume  12 . More specifically, the inertable volume  12  comprises an upper portion  16  and a lower portion  18 , and the main opening  14  is located in the lower portion  18  of the inertable volume. 
     In order to avoid having to replenish an additive manufacturing machine during production, the inertable volume  12  has a capacity of at least five litres and that can be up to two thousand litres, with the capacity of the inertable volume being adapted to the volume of the manufacturing zone or zones of the additive manufacturing machine, taking into account the amount of powder that can be excessively deposited by the means for layering or spraying powder. 
     In order to avoid the creation of powder retention zones in the container  10 , the section S 12  of the inertable volume  12  increases gradually over at least part of the height H 10  of this inertable volume  12  and from the lower portion  18  towards the upper portion  16  of this inertable volume  12 . Therefore, the section S 12  of the inertable volume  12  increases gradually above the main opening  14 , thus promoting the flow of powder towards this main opening. 
     In a first embodiment shown in  FIGS. 1 and 2 , the section S 12  of the inertable volume  12  increases gradually in the lower portion  18  of this inertable volume  12  and this section S 12  of the inertable volume  12  remains constant in the upper portion  16  of this inertable volume  12 . 
     In a second embodiment shown in  FIGS. 3 and 4A and 4B , the section S 12  of the inertable volume  12  increases gradually over the entire height H 10  of this inertable volume  12 . 
     The inertable volume  12  can assume a frustoconical or pyramid shape in the portion where its section S 12  increases gradually. 
     In the first and second embodiment of the container shown in the figures, the inertable volume  12  assumes the shape of a 4-sided pyramid with rounded edges between its different faces in the portion where its section S 12  increases gradually. 
     In order to avoid any exposure of the powder to the air present outside the inertable volume  12 , the main opening  14  is equipped with a passive half-valve  20  allowing this main opening  14  to be closed in an airtight and humidity-proof manner. 
     In combination with this passive half-valve  20 , and in order to be able to fill the inertable volume  12  with an inert gas, the container  10  comprises at least two inerting tappings, at least one first upper tapping  22  granting access to the upper portion  16  of the inertable volume and at least one second lower tapping  24  granting access to the lower portion  18  of the inertable volume. 
     Advantageously, the presence of at least two lower and upper tappings allows the inertable container to be completely filled with inert gas irrespective of the position in which the container is used. 
     According to the invention, an inert gas is a gas that does not cause a physicochemical reaction, such as, for example, oxidation, adsorption or absorption, likely to degrade the features and the quality of the additive manufacturing powder. For example, for some powders, an inert gas can be nitrogen, argon, helium or a mixture of two or three of these gases. 
     Thus, when the container is used to supply an additive manufacturing machine or another additive manufacturing device with powder, the container is used with its main opening towards the bottom, and the inert gas is introduced into the inertable volume through an upper tapping. However, in order to facilitate the flow of the powder towards the main opening, the inert gas also can be introduced into the inertable volume through a lower tapping. More specifically, by being introduced through a lower tapping, the inert gas circulates in the powder and allows a possible accumulation of powder to be broken that would have built up above the main opening. When the inert gas is thus introduced through a lower tapping, the upper tapping can be used to discharge the inert gas and thus limit the over-pressurization of inert gas in the inertable volume. 
     Conversely, when the container is used to receive powder from an additive manufacturing machine or from another additive manufacturing device, the container is used with its main opening towards the top, and the inert gas is introduced into the inertable volume through a lower tapping. 
     Finally, when the container has been opened, emptied and exposed to the outside air, the passive half-valve is closed, and two tappings granting access to the inertable volume are used to refill the inertable volume with an inert gas, with a first tapping being used to introduce the inert gas into the inertable volume and the other tapping allowing the non-inert gases to be discharged that are present inside the inertable volume and are driven out by the inert gas introduced via the first tapping. 
     As illustrated in the various figures, with the upper portion of the inertable volume being closed by an upper wall  27 , each lower tapping  24  is located in the immediate vicinity of the main opening  14 , and each upper tapping  22  is located in the immediate vicinity of the upper wall  27 . 
     With a view to hermetically sealing the inertable volume, the passive half-valve  20  comprises a body  25  supporting a butterfly valve  26  for closing the main opening  14  of the container  12  and means  28  for locking this butterfly valve in a closed position. 
     These locking means  28  are unlocked by coupling the passive half-valve with an active half-valve, with the locking means allowing the separation of the passive half-valve and of the active half-valve only when the butterfly valve  26  is in a closed position, and the locking means  28  keeping the butterfly valve  26  in a closed position as long as the passive half-valve is not coupled with an active half-valve. 
     An active half-valve  30  intended to be coupled with the passive half-valve  20  of the container  10  is shown in  FIG. 1 . This active half-valve  30  comprises a body  32  supporting a butterfly valve  34  intended to be contiguous with the butterfly valve  26  of the passive half-valve  20 . Furthermore, this active half-valve  30  also comprises an actuator  36 , for example, a pneumatic actuator, allowing the butterfly valve  34  of the active half-valve  30  to be rotated. 
     Furthermore, the means  28  for locking the butterfly valve in a closed position are unlocked by coupling the butterfly valve  26  of the passive half-valve with the butterfly valve  34  of the active half-valve, the active half-valve comprising means for unlocking the means  28  for locking the passive half-valve  20 . 
     For example, the butterfly valve  34  of the active half-valve forms or supports the means for unlocking the means  28  for locking the passive half-valve  20 . 
     With the means  28  for locking the passive half-valve  20  assuming, for example, the shape of at least one key or of at least one stud that are translationally movable, moving this key or this stud when the passive half-valve is coupled with an active half-valve allows the butterfly valve  26  and the butterfly valve  34  to be free to rotate about an axis passing through the main opening  14 . 
     In order to activate the unlocking of the means  28  for locking the passive half-valve  20 , the means for unlocking the active half-valve assume, for example, the shape of at least one pin, or of at least one cam, or more simply of at least one surface allowing the key or the stud of the means  28  for locking the passive half-valve  20  to be moved. The pin, the cam or the surface of the unlocking means are supported, for example, by the butterfly valve  34  of the active half-valve. 
     When the active half-valve is coupled to the passive half-valve, the means for unlocking the active half-valve unlock the means for locking the passive half-valve, the butterfly valve  34  of the active half-valve is contiguous with the butterfly valve  26  of the passive half-valve, and the rotation of the butterfly valve  34  under the effect of the actuator  36  of the active half-valve causes the butterfly valve  26  of the passive half-valve to rotate and therefore causes the main opening  14  to open. 
     In the second embodiment of the container shown in  FIGS. 3, 4A and 4B , with the inertable volume  12  comprising a right-hand side  38  and a left-hand side  40 , the container comprises a lower tapping  24  and an upper tapping  22  on the right-hand side of the inertable volume, and the container comprises a lower tapping  24  and an upper tapping  22  on the left-hand side of the inertable volume. 
     Still according to the second embodiment of the container shown in  FIGS. 3, 4A and 4B , with the container  10  comprising a lower portion  42  and an upper portion  44 , the container comprises at least two lower connectors  46  positioned in the lower portion  42  of the container and at least two upper connectors  48  positioned in the upper portion  44  of the container. A first upper connector  48  and a first lower connector  46  are connected by the same pipe  50  to a lower tapping  24  granting access to the lower portion  18  of the inertable volume, and a second upper connector  48  and a second lower connector  46  are connected by the same pipe  52  to an upper tapping  22  granting access to the upper portion  16  of the inertable volume. 
     Thus, in the second embodiment of the container, with the container comprising lower  24  and upper  22  tappings on the right-hand  38  and left-hand  40  sides of the inertable volume, the container comprises four connectors on each side of the inertable volume. On the right-hand side  38  of the inertable volume, a lower connector  46  and an upper connector  48  are connected by the same pipe  50  to a lower tapping  24 , and a lower connector  46  and an upper connector  48  are connected by the same pipe  52  to an upper tapping  22 . Furthermore, on the left-hand side  40  of the inertable volume, a lower connector  46  and an upper connector  48  are connected by the same pipe  50  to a lower tapping  24 , and a lower connector  46  and an upper connector  48  are connected by the same pipe  52  to an upper tapping  22 . 
     As illustrated in the various figures, the container  10  comprises a frame  54 , inside which the inertable volume  12  is placed. This frame is substantially parallelepipedic and it allows the handling of the inertable volume  12  and therefore of the container to be facilitated. 
     Advantageously, the lower  46  and upper  48  connectors are supported by the frame  54  of the container. 
     In the container according to the invention, the upper portion  16  of the inertable volume forms part of the upper portion  44  of the container and the lower portion  18  of the inertable volume forms part of the lower portion  42  of the container. Thus, the dimensions of the container  10  are substantially identical to the dimensions of the inertable volume  12 . 
     Still with a view to facilitating the handling of the inertable volume  12 , the container  10  comprises castors  56  in the lower portion  42  and in the upper portion  44 . These castors  56  are supported by the frame  54  of the container. 
     To the same end, the frame  54  of the container allows a retractable handle  58  to be accommodated in the upper portion  44  of the container or in the lower portion  42  of the container, as a function of the orientation in which the container is used (main opening towards the top or main opening towards the bottom). 
     Finally, to allow the inside of the inertable volume  12  to be fully cleaned, the container  10  comprises an additional opening  60  granting access to the inside of the inertable volume  12 , with this additional opening being equipped with a closure cover  62 . 
     Advantageously, the additional opening  60  is established in the upper portion  44  of the inertable volume  12 . More specifically, the additional opening  60  is established through the upper portion  27  of the inertable volume  12 . 
     This additional opening  60  is big enough to be able to allow the inside of the inertable volume  12  to be fully cleaned and the inside of the inertable volume  12  to be properly visually inspected, with this visual inspection being used to ensure that the inside of the inertable volume  12  is clean and free from any impurities before it is reclosed and refilled with inert gas and before a new batch of additive manufacturing product is introduced therein.