Patent Publication Number: US-11642847-B2

Title: 3D build platform refill opening and cap

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/084,141, filed on Sep. 11, 2018, which is a 371(c) National Phase Application of International Application No. PCT/2016/032133, filed May 12, 2016, both of which are herein incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Three dimensional (3D) printers, also referred to as additive manufacturing machines, commonly operate by using a material to generate a 3D object layer-by-layer. In some 3D printing systems, powder is delivered to a build platform from a powder storage unit. A layer of the powder is leveled and excess powder can be recycled. Portions of the layer of powder can be printed and fused using an energy source. The 3D printing system can operate at high temperatures to melt and fuse the portions of powder that are printed when building a part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram of a side view of an example of a 3D printing system of the present disclosure; 
         FIG.  2    is a block diagram of an example build unit of the 3D printing system; 
         FIG.  3    is a cross-sectional diagram of an example build unit; 
         FIG.  4    is isometric view of an example of a cap; 
         FIG.  5    is a side view of an example handle on the cap; 
         FIG.  6    is an isometric view of an example of the cap in an opening in a top surface of a build platform; 
         FIG.  7    is a cross-sectional diagram of an example of the opening in the top surface of the build platform; 
         FIG.  8    is a cross-sectional diagram of an example of a supply hose connected to the opening; and 
         FIG.  9    is a flow diagram of an example method for supplying build material through an opening in a top surface of a build platform. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure discloses examples of a build platform on a build unit that includes an opening in a top surface of the build platform and a cap. The build unit has an opening in a top surface of a build platform of the build unit. The opening may provide access to an enclosed build material storage unit within the build unit and below the build platform. As a result, the build material storage unit may be refilled with build material via a gravity fill as quickly as possible. Any clouds of dust are contained within the build material storage unit and do not form in the print zone over the build platform. 
     The opening in the top surface of the build platform provides easy access to the powder storage unit. For example, the opening allows an operator to easily view a powder level remaining in the powder storage unit. In addition, the powder may be periodically changed or the powder storage unit may be periodically cleaned. As a result, the opening allows for easy access to the powder storage unit. 
     In addition, when the opening is plugged with a cap, the top surface and the cap may be designed to have uniform thermal conductivity to ensure that the entire top surface has an even temperature profile. For example, integrity of the part being printed can be compromised if a cool spot forms over the cap, or there are large temperature differences between the cap and the top surface of the build platform. 
       FIG.  1    illustrates an example of a 3D printing system  100 . The 3D printing system may include a build unit  102 , a printer or 3D printer  104  and a build material supply/post-processing component  106 . In one implementation, the build unit  102  may store a build material that is used to build a part using additive printing/processing layer by layer. The build material may be a powder (e.g., a metallic powder, a ceramic powder, and the like). In addition, the build unit  102  may provide a vertically movable build platform upon which the part is built. The build material may be delivered up from the sides of the build unit  102  onto the build platform. The build platform may move lower after each layer is printed. 
     In one example, the build unit  102  may be connected to the build material supply/post-processing component  106  to receive the build material. For example,  FIG.  1    shows the build material supply/post-processing component  106  with the build unit  102  connected. 
     After the build unit  102  receives the build material, the build unit  102  may be disconnected from the build material supply/post-processing component  106  and connected to the printer  104 .  FIG.  1    shows the printer  104  with the build unit  102  connected. 
     In some implementations, the printer  104  may have a first print head for applying a fusing agent to areas of the build material that will be fused to print a layer of the part that is being printed. The first print head may also apply a detailing agent on some areas of the build material to help prevent the build material from fusing in the areas that will not be fused. Then the printer  104  may have a second print head that applies energy to fuse the areas of the build material with the fusing agent. The build platform of the build unit  102  may be lowered and a new layer of build material may be added on top of the layer of build material that was printed. The process may be repeated until the part is completed. 
     The build unit  102  may be removed from the printer  104  after printing of the part has completed. The build unit  102  can then be connected to the build material supply/post-processing component  106  again to extract the part. In addition, the build material supply/post-processing component  106  may also recover and recycle the unfused build material. 
     Although the build unit  102  is shown as being a separate component from the printer  104 , it should be noted that the build unit  102  may be part of the printer  104 . For example, the build material may be supplied in the printer  104  and the build platform may be part of the printer  104  rather than being deployed as part of a removable build unit such as the build unit  102 . 
       FIG.  2    illustrates an example block diagram of the build unit  102  that includes an opening  206  on a top surface  212  of a build platform  210 . In one example, feed trays  204  may be located on each side of the build platform  210 . 
     In one implementation, the build platform  210  may be vertically movable within the build unit  102 . For example, as build material is placed on the build platform  210 , printed and fused, the build platform  210  may be lowered to receive another layer of build material. Then the process may be repeated until the 3D part is completely printed. 
     In some implementations, the opening  206  may be easily accessible by a user or a technician. In other words, a user does not need to climb a ladder or a contraption above the build unit  102  to access the opening  206 . In one example, the opening  206  may be located at a height of less than six feet high. For example, the opening  206  may be located at a counter height of approximately four feet to five feet high. 
       FIG.  3    illustrates a cross-sectional diagram of the build unit  102 . A build material storage unit  208  may be located below the opening  206  and the top surface  212  of the build platform. The build material storage unit  208  may be enclosed and store a build material used to print a part via the additive process of the 3D printing system  100 . 
     In one implementation, the build material may be fed up the sides of the build material storage unit  208  via an auger that dispenses the build material through the feed trays  204 . The build material may be dispensed into a print zone  302 . 
     As discussed above, the build material storage unit  208  may be enclosed and located below the build platform  210 . As a result, the build material storage unit  208  may be quickly filled with build material via a gravity fill system. In addition, no hazardous dust clouds of build material may form in the print zone  302  from quickly pouring the build material into the build material storage unit  208 . 
     In one embodiment, the opening  206  may also provide easy access to the build material storage unit  208 . For example, an operator may quickly view the build material level by looking into the opening  206 . In addition, the opening  206  may provide easy access to change the build material or clean the inside of the build material storage unit  208 . 
     In one example, the opening  206  may be a circular shape and located in a center of the top surface  212  of the build platform  210 . However, it should be noted that the opening  206  may be any shape and located anywhere on the top surface  212  of the build platform  210 . 
       FIG.  4    illustrates an isometric view of an example of a cap  400  that may be inserted into the opening  206  to plug or seal the opening  206 . In one example, the cap  400  may include a top portion  402 , a body portion  404  and a handle  406 . The top portion  402  may be coupled to the body portion  404  (or molded as a single integral piece) and may have a shape that corresponds to the opening  206 . For example, if the opening  206  is circular, the top portion  402  and the body portion  404  may also have a corresponding circular shape of similar dimensions (e.g., length, width, diameter, and the like) as the opening  206 . 
     In one implementation, the top portion  402  and the body portion  404  may be fabricated from a conductive material that has a conductivity similar to the top surface  212  of the build platform  210 . In other words, the cap  400  may be a conductive cap. In one example, the top portion  402  and the body portion  404  may be fabricated from a same metal as the top surface  212  of the build platform  210 . In other words, if the top surface  212  of the build platform  210  is made from aluminum, a metal alloy, and the like, then the top portion  402  and the body portion  404  may be fabricated from the same aluminum, metal alloy, and the like. As a result, the entire top surface  212 , including a top surface of the top portion  402  of cap  400 , may have the same thermal conductivity and no differences in temperature gradients may be formed on the top surface  212  of the build platform  210 . In other words, the top portion  402  of the cap  400  and the top surface  212  of the build platform  210  may have a uniform thermal conductivity. 
     In one implementation, the body portion  404  may include a mating mechanism  410  to mate with a corresponding mechanism in the opening  206 . For example, the mating mechanism  410  may be a mechanical connection such as a twist and lock mechanism, or threads to allow the cap  400  to be screwed in, a lock with springs and ball plungers, magnets, and the like. 
     In some implementations, the mating mechanism  410  may be oriented such that the handle  406  is positioned to fall in a direction of movement of a spreader of the printer  104  when the cap  400  is inserted into the opening  206 . In other words, the mating mechanism  410  may ensure that the handle  406  is in a position such that as a build material spreader moves over the build platform  210 , the spreader may knock down the handle  406  without interfering with the movement of the spreader. 
     In one example, the handle  406  may be coupled to the top portion  402 . The top portion  402  may also include a cavity  408 . The cavity  408  may have a similar shape (e.g., the shape of the outer perimeter and thickness) as the handle  406 . The handle  406  may rest in the cavity  408  such that the top surface  212 , the top portion  402  and the handle  406  are all co-planar during operation of the printer  104 . In other words, the top surface  212 , the top portion  402  and the handle  406  lie on a single plane or the same plane. Said another way, the top surface of the handle  406  when resting in the cavity  408  is not lower than the top surface of the top portion  402  of the cap  400 . As a result, the top portion  402  and the handle  406  may not interfere with operation of the rollers and printer carriage of the printer  104 . In addition, the top portion  402  and the handle  406  may not cause changes in elevation in the layers of build material that are spread across the top of the build platform. 
       FIG.  5    illustrates a side view of an example of the handle  406 . In one implementation, the handle  406  may be designed to have a range of motion of less than 90 degrees relative to the top surface  212  of the build platform to 0 degrees when resting in the cavity  408 . 
     For example,  FIG.  5    illustrates an angle  502  measured between a dashed line  504  and the top surface  212 . The dashed line  504  is illustrated as being at an angle of 90 degrees relative to the top surface  212 . The handle  406  may be designed to have a range of motion that does not reach the dashed line  504  to a resting position flush in the cavity  408 . 
     The design of the range of motion of the handle  406  ensures that the handle  406  will fall via gravity. The range of motion of the handle  406 , the design of the mating mechanism  410  that ensures that the handle  406  falls in a direction of movement of the spreader into the cavity  408 , and the cap  400  may be designed to ensure no component interferes with the movement of the spreader or other mechanical portions of the printer  102  during processing of the build material. 
     For example,  FIG.  6    illustrates an example of the cap  400  that is inserted into the opening  206  in the top surface  212  of the build platform  210 . The handle  406  may reset in the cavity  408  such that the top portion  402  of the cap  400  is flush, co-planar, or on the same plane, with the top surface  212  of the build platform  210 . In other words, when build material is laid on top of the build platform  210  and flattened by the spreader, no changes of elevation would exist in the build material. 
       FIG.  7    illustrates a cross-sectional diagram of an example of the opening  206  in the top surface  212  of the build platform  210 . In one embodiment, the opening  206  may include a corresponding mating mechanism  708 . For example, the mating mechanism  410  of the cap  400  may align and mate with the corresponding mating mechanism  708  of the opening  206 . As described above, in some implementations, the corresponding mating mechanism  708  may be aligned such that when the cap  400  is inserted into the opening, the handle  406  will fall in a direction of movement of the spreader. 
     In one example, the opening may include a bottom ring  706 . The surface of the bottom ring  706  may include a hose valve opening mechanism  702  and a magnet  704 .  FIG.  8    illustrates an example of a supply hose  802  that is inserted into the opening  206  to fill the build material storage unit  208  with build material. The hose  802  may include a valve  804  to prevent loose build material from spilling out of the hose  802 . The hose  802  may also include a sensor  806  to detect the magnet  704 . 
     In one example, the sensor  806  may detect the magnet  704  indicating that the hose  802  has been inserted into the opening  206  properly. In one example, the hose valve opening mechanism  702  may comprise a hook that protrudes perpendicular to a surface of the bottom ring  706 . The hook may turn and lock the valve  804  into an open position. As a result, when the hose  802  is properly inserted into the opening  206  (e.g., as indicated by the sensor  806  detecting the magnet  704 ) the valve  804  may be opened and ready for filling the build material storage unit  208 . 
       FIG.  9    illustrates a flow diagram of an example method  900  for supplying build material through an opening in a top surface of a build platform. In one example, the blocks of the method  900  may be performed the build unit  102  or the 3D print system  100 . 
     At block  902 , the method  900  begins. At block  904 , the method  900  provides for a conductive cap to be removed from an opening in a top surface of a 3D build platform. For example, the conductive cap may be removed to allow for access to the opening. The 3D build platform may be located on top of a movable build unit. The build unit may be moved into a build material supply/post-processing component of a 3D printing system after the conductive cap is removed. 
     In one example, the conductive cap may be removed with a handle that is coupled to a top surface of the conductive cap. The handle may rest in a cavity in the top surface of the conductive cap and be designed to automatically fall into the cavity even if the handle is accidently left up. 
     At block  906 , the method  900  provides for a supply hose to be inserted into the opening. In one example, the supply hose may be part of the build material supply/post-processing component of a 3D printing system. The supply hose may be used to fill the build material storage unit in the build unit with build material that is used to print a 3D part. 
     At block  908 , a presence sensor is triggered to determine that the supply hose is connected. In one example, the build unit may not contain any sensors due to the high operating temperatures used in 3D printing. Rather, the sensors may be contained in the supply hose. The opening in the build unit may contain a magnet that is detected by the presence sensor on the supply hose to indicate that the supply hose has been properly inserted into the opening. 
     In addition, the opening may contain a hose valve opening mechanism that opens a valve at an end of the supply hose. For example, an end of the supply hose may have a valve to prevent loose or excess build material from spilling out of the supply hose. The hose valve opening mechanism may cause the mechanical valve on the end of the supply hose to open and remain open. 
     At block  910 , build material is supplied into an enclosed build material storage unit below the 3D build platform. In one example, the build material may be supplied via a gravity fill. In other words, the build material may be poured from a source that is located above the opening in the build unit. 
     In addition, the build material may be poured at a maximum speed or without any pouring speed control. Since the build material storage unit is enclosed below the top surface of the build platform, any clouds of build material will remain inside the build material storage unit. The build material may be supplied into the build material storage unit as quickly as possible without fear of forming potentially dangerous clouds of build material. 
     At block  912 , the conductive cap is replaced into the opening in the top surface of the 3D build platform. For example, the supply hose may be disconnected and the build unit may be removed from the build material supply/post-processing component. The conductive cap may be placed into the opening and the build unit may be moved to the printer to build the 3D part. For example, the handle may be used to align a mating mechanism on the conductive cap with a corresponding mating mechanism in the opening. After the conductive cap is inserted, the handle may be lowered into the cavity in the top surface of the conductive cap. When the handle is lowered, the handle, the top surface of the conductive cap and the top surface of the build platform of the build unit may be co-planar. At block  914 , the method  900  ends. 
     It will be appreciated that variants of the above-disclosed and other features and functions, or alternatives thereof, may be combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.