Patent Publication Number: US-2021187848-A1

Title: Powder container

Description:
BACKGROUND 
     Additive manufacturing machines, sometimes called 3D printers, produce objects by building up layers of material. Digital data may be processed into slices each defining that part of a layer or layers of build material to be formed into the object. In some additive manufacturing machines, the object slices are formed in a powdered build material spread in layers over the work area. Powder in each of the successive layers may be fused in the desired pattern to form a solid object. 
    
    
     
       DRAWINGS 
         FIGS. 1 and 2  are isometric views illustrating one example of a powder container. 
         FIG. 3  is a section view taken along the line  3 - 3  in  FIG. 2 . 
         FIG. 4  is an isometric and partial section view of the example container shown in  FIGS. 1-3 . 
         FIGS. 5-8  present a sequence of side section views illustrating a supply operation in the example container shown in  FIGS. 1-4 . 
         FIG. 9  is a front section view detail illustrating the example container shown in  FIGS. 1-4  during a supply operation. 
         FIGS. 10-15  are side and front elevation views illustrating examples of a vane configuration for the lift in a powder container such as that shown in  FIGS. 1-4 . 
         FIGS. 16 and 17  are side section views illustrating a supply operation in a powder container using the example vane configuration shown in  FIGS. 14 and 15 . 
         FIGS. 18-23  are side and front elevation views illustrating other examples of a vane configuration for the lift in a powder container such as that shown in  FIGS. 1-4 . 
         FIG. 24  is a section view illustrating another example of a powder container. 
     
    
    
     The same part numbers designate the same or similar parts throughout the figures. The figures are not necessarily to scale. 
     DESCRIPTION 
     It may be desirable to minimize the height of some additive manufacturing machines. In machines that use gravity to deliver the powdered build material to the manufacturing zone, powder supply containers are located above the manufacturing zone. The height of the machine, therefore, can be effected by the height of the powder supplies. A new, compact powder supply container has been developed to help reduce the effect of the powder supply on the height of an additive manufacturing machine. In one example, a powder supply container includes forward and rearward troughs in plane with one another along the bottom of the supply chamber. An auger in the forward trough conveys powder to the outlet while a sweep in the rearward trough sweeps powder from the rearward trough into the forward trough. 
     A swept trough configuration enables powder to be stored in the container at a lower level than is possible if gravity alone is used to feed powder to the auger, allowing an equal supply capacity in a shorter container or an increased supply capacity in the same height container. The reduced height (or increased capacity) can be significant. For example, a PA12 build material powder may require a slope of 32° or more along the bottom of the container to reliably feed powder toward the outlet. A swept trough container with the same horizontal footprint, by comparison, could be 20% shorter and still achieve the same supply capacity. Conversely, a swept trough container the same height as a gravity feed container could hold 20% more powder within the same horizontal footprint. 
     While examples of the new container were developed to supply powdered build materials for additive manufacturing, examples are not limited to additive manufacturing. The examples described herein and shown in the figures illustrate but do not limit the scope of the patent, which is defined in the Claims following this Description. 
     As used in this document, “and/or” means one or more of the connected things. 
       FIGS. 1 and 2  are isometric views illustrating one example of a powder container  10 , such as might be used to supply powdered build material in an additive manufacturing machine.  FIG. 3  is a section view taken along the line  3 - 3  in  FIG. 2 .  FIG. 4  is an isometric and partial section view of container  10  shown in  FIGS. 1-3 . Referring to  FIGS. 1-4 , container  10  includes a housing  12  that defines an interior chamber  14  to hold a powder, an inlet  16  to chamber  14 , and an outlet  18  from chamber  14 . A cap  20  caps inlet  16  in  FIG. 1 . A portable container  10  may include a handle  21 , shown in  FIG. 1 . 
     A first basin  22  and a second basin  24  are formed at the bottom part  26  of interior chamber  14 . Basins  22  and  24  are separated by a spillway  28 . In this example, first basin  22  is located forward of second basin  24  in the direction powder is moved toward outlet  18  (from basin  24  into basin  22  to outlet  18 ). For an elongated powder supply chamber  14  shown in  FIGS. 1-4 , each basin  22 ,  24  is configured as a trough that extends the full width of the bottom part  26  of chamber  14 . In this example, outlet  18  is a point outlet located at one end of forward trough  22 . In other examples, outlet  18  may be configured as a line outlet extending along the bottom of trough  22 . 
     As shown in  FIGS. 3 and 4 , container  10  includes a lift  30  mounted to housing  12  to lift powder out of rearward trough  24  into forward trough  22 . As described in detail below with reference to  FIGS. 5-8 , in this example lift  30  is configured as a sweep that rotates through trough  24  to sweep powder up and over spillway  28  into forward trough  22 . Also in this example, an auger  32  is mounted to housing  12  in forward trough  22  to convey powder along trough  22  to outlet  18 . 
     Sweep  30  is mounted to a shaft  34  operatively connected to a drive mechanism  36  to rotate shaft  34 . Drive mechanism  36  includes a motor  38  and a drive train  40  connecting motor  38  to sweep shaft  34 . In this example, as shown in  FIG. 2 , a single motor  38  drives sweep  30  and auger  32 . Sweep drive train  40  includes a torque limiter  42  to keep the drive torque applied to sweep shaft  34  predictably below a desired threshold, thus allowing sweep  30  to stall when the powder inside chamber  14  is deep enough to gravity feed into forward trough  22  while still allowing auger  32  to auger powder toward outlet  18 . The stall threshold may be set, for example, based on the characteristics of the powder to be supplied from chamber  14 , the surface area of sweep  30 , and the depth of the rearward trough  24 . 
     Drive train  40  also includes drive gears  44 ,  46  connected through a series of idler gears  48 . Idler gears  48  are omitted from drive train  40  in  FIG. 4  to more clearly show sweep  30  in trough  24 . Other configurations for drive mechanism  36  are possible. For example, sweep  30  and auger  32  could be driven independently of one another and more or fewer drive gears and/or idler gears could be used. 
       FIGS. 5-8  present a sequence of side section views illustrating a supply operation using a container  10  shown in  FIGS. 1-4 .  FIG. 9  is a front section view detail illustrating the example container  10  during a supply operation. In  FIG. 5 , the level of powder  50  in chamber  14  is high enough to gravity feed into forward trough  22 . Thus, sweep  30  is stalled and auger  32  is turning, as indicated by rotation arrow  49  in  FIG. 5 , to auger powder  50  to an open outlet  18  (shown in  FIG. 9 ). In  FIG. 6 , the level of powder  50  in chamber  14  has dropped to a level that allows sweep  30  to turn, as indicated by rotation arrow  51 , to sweep powder  50  over spillway  28  into forward trough  22 . Auger  32  continues to turn, augering powder  50  to outlet  18  as shown in  FIG. 9 . Sweep  30  may be rotated continuously or intermittently to sweep powder  50  out of rearward trough  24  into forward trough  22  as shown in  FIGS. 7 and 8  until the supply of powder  50  is exhausted. 
     As best seen in the section views of  FIGS. 3 and 5-8 , in this example the bottom of troughs  22 ,  24  lie in the same plane (and sink to the same depths) to help maximize the powder supply capacity within the 3D space occupied by container  10  and enabling higher volumetric efficiencies compared to a gravity feed supply. 
       FIGS. 10-15  are side and front elevation views illustrating examples of the vane configuration for a sweep or other lift  30  in a powder container  10 . In the example shown in  FIGS. 10 and 11 , lift  30  is configured as a straight rectangular solid vane  52 . In the example shown in  FIGS. 12 and 13 , lift  30  is configured as a straight rectangular apertured vane  52  with a single opening  54 . An apertured vane  52  may be desirable in some implementations, for example, to help tune the stall threshold, lift capacity and/or agitating function of lift  30 . 
     In the example shown in  FIGS. 14 and 15 , lift  30  is configured as a curved rectangular solid vane  52 . As shown in  FIGS. 16 and 17 , a “scooped” lift  30  with a curved vane  52  such as that shown in  FIGS. 14 and 15  may be rotated counter-clockwise through rearward trough  24  in chamber  14  to scoop up powder  50  and dump it into forward trough  22 . 
       FIGS. 18-23  are side and front elevation views illustrating other examples of a vane configuration for the lift in a powder container  10 . In the example shown in  FIGS. 18 and 19 , lift  30  is configured as a curved rectangular apertured vane  52  with a single opening  54 . In the examples shown in  FIGS. 20-23 , lift  30  is configured as a straight ( FIGS. 20 and 21 ) or curved ( FIGS. 22 and 23 ) rectangular apertured vane  52  with multiple openings  54 . For an apertured vane  52 , the size, shape and number of openings  54  may be varied to achieve the desired degree of stall, lift and/or agitation. Also, while a lift  30  with a single vane  52  is shown, lift  30  may include multiple vanes  52 , for example to increase the sweep frequency for a more continuous supply of powder to the auger as the supply of powder is depleted. 
       FIG. 24  illustrates another example of a powder supply container  10 , in which multiple troughs  24  and multiple sweeps  30  are arranged in series so that powder  50  in one trough  24  is swept into the next trough  24  and so on until the last trough  24  in the series, from which powder  50  is swept into the forward, discharge trough  22 . Although not shown in  FIG. 24 , single motor may be used to drive multiple sweeps through individual torque limiters to keep the drive torque applied to each sweep predictably below a desired threshold (as described above for a single sweep  30  in  FIGS. 2 and 4 ). 
     As noted above, the examples shown in the figures and described herein illustrate but do not limit the patent, which is defined in the following Claims. 
     “A”, “an” and “the” used in the claims means one or more. For example, “a flap” means one or more flaps and “the flap” means the one or more flaps.