Patent Publication Number: US-2020282648-A1

Title: A container to hold build material for additive manufacturing

Description:
BACKGROUND 
     Additive manufacturing machines produce 3D (three-dimensional) objects by building up layers of material. Some additive manufacturing machines are commonly referred to as “3D printers.” 3D printers and other additive manufacturing machines make it possible to convert a CAD (computer aided design) model or other digital representation of an object into the physical object. The model data may be processed into slices each defining that part of a layer or layers of build material to be formed into the object. 
    
    
     
       DRAWINGS 
         FIGS. 1-4  illustrate one example of a build material supply cartridge for an additive manufacturing machine.  FIG. 1  is an isometric showing the exterior of the example cartridge.  FIG. 2  is an exploded view of the example cartridge.  FIGS. 3 and 4  are partial sections viewed along the line  3 - 3  in  FIG. 1 . 
         FIGS. 5-7  illustrate another example of a build material supply cartridge for an additive manufacturing machine.  FIG. 5  is an isometric showing the exterior of the example cartridge.  FIG. 6  is a partial section viewed along the line  6 - 6  in  FIG. 5 .  FIG. 7  is a partially exploded view of the example cartridge. 
         FIG. 8  illustrates one example of a group of build material containers for additive manufacturing. 
     
    
    
     The same part numbers designate the same or similar parts throughout the figures. The figures are not necessarily to scale. 
     DESCRIPTION 
     In some additive manufacturing processes, powdered build materials are used to form a solid object. Particles in each of many successive layers of build material powder are thermally, chemically or otherwise fused in a desired pattern to form the object. HP Inc. has developed a new build material supply system for additive manufacturing in which replaceable build material powder supply cartridges are integrated into the additive manufacturing machine. The cartridges are oriented horizontally and rotated in the machine to move the powder to inhibit agglomeration and to dispense powder from the cartridges. Examples of the new supply system are disclosed in international patent application nos. PCT/US2017/055269 titled CHAMBER FOR STORING BUILD MATERIAL and PCT/US2017/055309 titled SUPPLY STATION FOR DISPENSING BUILD MATERIAL, both filed Oct. 5, 2017. When a cartridge is rotated the build material inside the cartridge slides along the interior surfaces of the cartridge. Friction between the build material powder and the surfaces of the cartridge may generate static electricity. A buildup of static electricity in the material in a supply cartridge creates a risk of damage due to uncontrolled discharge of the static electricity and may adversely affect the flowability of the powder. 
     Accordingly, new structures have been developed to inhibit static electricity forming in the build material in a supply cartridge. In one example, a supply cartridge is made of the same material as the build material contained in the cartridge or a material with a charge affinity similar to the charge affinity of the build material. Friction between the same materials or materials with a similar charge affinity is significantly less likely to generate static electricity than friction between dissimilar materials. In another example, a supply cartridge includes an anti-static interior to partially or fully contain the build material. The anti-static interior may be implemented, for example, as a liner made of the same or similar material as the build material contained in the cartridge. An anti-static liner enables the use of a less expensive exterior shell material while still inhibiting static electricity forming in the build material. 
     Examples are not limited to powdered build materials or build material supply cartridges. Examples may be used to help inhibit static electricity in other containers and in other forms of build materials for additive manufacturing. The examples described herein 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; “anti-static” means to inhibit static electricity forming in a material; and a “similar” charge affinity means±30 nC/J (nano Coloumbs per Joule). 
       FIGS. 1-4  illustrate one example of a build material supply cartridge  10  for an additive manufacturing machine. Cartridge  10  in  FIGS. 1-4  is structured to hold a powdered or other form of unfused build material  12  ( FIG. 3 ) in a horizontal orientation so that the cartridge may be rotated in the machine to move the build material to inhibit agglomeration and to dispense build material from the cartridge. Build material  12  is depicted by stippling in the figures. Cartridge  10  includes a rigid cylindrical container  14  made of the same material, or a material with a similar charge affinity, as build material  12  contained in the cartridge. While a container  14  made of the same material as build material  12  may be used to achieve a higher degree of protection against the buildup of static electricity in a build material  12 , a container  14  made of a material with a similar charge affinity to build material  12  may deliver an acceptable degree of protection against static buildup at a lower cost and/or to deliver more desirable manufacturing characteristics. Polyamide powder is a commonly used build material for additive manufacturing. Thus, for one example, container  14  is made of a polyamide for a cartridge  14  that is to contain a polyamide build material powder  12 . 
     Friction between build material  12  and a container  14  made from the same or a similar material is significantly less likely to create static electricity than friction between build material  12  and a container made of a different material. Thus, for a supply cartridge  10  that is rotated inside the additive manufacturing machine as part of the supply process, container  14  made of the same or a similar material as build material  12  provides an anti-static interior that inhibits static electricity forming in build material  12  moving against the interior of the container. 
     The structural configuration and function of a build material supply cartridge like cartridge  10  shown in  FIGS. 1-4  is disclosed in more detail in PCT/US2017/055269 titled CHAMBER FOR STORING BUILD MATERIAL and PCT/US2017/055309 titled SUPPLY STATION FOR DISPENSING BUILD MATERIAL, both filed Oct. 5, 2017 and incorporated herein by reference in their entirety. 
     Referring to  FIGS. 1-4 , cartridge  10  includes container  14  and a base  16  that together enclose an interior chamber  18  to hold build material  12 . Container  14  may include a handle  20 . Build material  12  may flow out of and/or into chamber  18  through an opening  22  in base  16 . A valve  24  controls the flow of build material  12  through opening  22 . The interior surface  26  of a cylindrical or barrel shaped container  14  is structured to move build material  12  axially toward or away from base  16  as cartridge  10  is rotated, depending on the direction of rotation, for example with helical raised portions  28 , commonly referred as “flighting”, that auger build material  12  along the container when cartridge  10  is rotated. Base  16  is structured to move build material  12  radially toward or away from opening  22  as cartridge  10  is rotated, depending on the direction of rotation, for example with an Archimedes screw  30 . 
     In this example, valve  24  includes an auger  32  to move build material  12  axially through opening  22 . Auger  32  may include a helical blade  34  that matches the spiral of base  16  to complete Archimedes screw  30 . Auger  32  is keyed to base  16  or otherwise operatively linked to container  14  so that auger  32  rotates with base  16  and container  14 . As best seen in the section detail of  FIG. 4 , valve  24  includes an actuator pin  36  that is pulled out to open valve  24 , as indicated by arrow  38 , and pushed in to close valve  24 , as indicated by arrow  40 . Valve  24  is closed in  FIG. 4 . An o-ring or other suitable seal  42  may be used to seal opening  22  when valve  24  is closed. In a dispensing operation, valve  24  is opened and cartridge  10  rotated in a dispensing direction so that container flighting  28 , base screw  30 , and valve auger  32  move build material  12  toward and through opening  22 . 
     Also in this example, the exterior surface  44  of container  14  includes a flat part  46 . A flat part  46  may be used to orient cartridge  10  in and align it to a receiving station in an additive manufacturing machine, as well help cartridge  10  to remain stable resting on or against a flat surface. 
       FIGS. 5-7  illustrate another example of a build material supply cartridge  10  for an additive manufacturing machine. Referring to  FIGS. 5-7 , cartridge  10  includes a container  14  with a shell  48  and an anti-static liner  50  that forms an interior surface  26  of container  14  along the barrel  52  of shell  48  between base  16  and handle  20 . Liner  50  may be implemented, for example, as a coating on the inside of shell  48  or as an insert into shell  48 . In one example, liner  50  is made of the same material as build material  12  or a material with a charge affinity similar to build material  12 . A replaceable liner  50  insert may be desirable, for example, to enable the use of a single shell with multiple interchangeable liners to accommodate different types of build material and/or to replace worn or damaged liners. 
     Build material  12  may pass out of and/or into an interior chamber  18  through an opening  22  in base  16 . A valve  24  controls the passing of build material  12  through opening  22 . The interior surface  26  of liner  50  is structured to move build material  12  axially toward or away from base  16  as cartridge  10  is rotated, depending on the direction of rotation, for example with helical flighting  28 . Base  16  is structured to move build material  12  radially toward or away from opening  22  as cartridge  10  is rotated, depending on the direction of rotation, for example with an Archimedes screw  30 . In this example, valve  24  includes an auger  32  to move build material  12  axially through opening  22 . Auger  32  may include flighting  34  that matches the spiral feature  30  of base  16  to complete an Archimedes screw  30 . 
     Auger  32  is keyed to base  16  or otherwise operatively linked to container  14  so that auger  32  rotates with base  16  and container  14 . As best seen in the section detail of  FIG. 4 , valve  24  includes an actuator pin  36  that is pulled out to open valve  24 , as indicated by arrow  38 , and pushed in to close valve  24 , as indicated by arrow  40 . Valve  24  is closed in  FIG. 4 . An o-ring or other suitable seal  42  may be used to seal opening  22  when valve  24  is closed. In a dispensing operation, valve  24  is opened and cartridge  10  rotated in a dispensing direction so that container flighting  28 , base screw  30 , and valve auger  32  move build material  12  toward and through opening  22 . Also in this example, the exterior surface  44  of container  14  includes a flat part  46 . A flat part  46  may also be used to orient cartridge  10  in and align it to a receiving station in an additive manufacturing machine, as well help cartridge  10  to remain stable resting on or against a flat surface. 
       FIG. 8  illustrates a group  54  of containers  14  made up of a single shell  48  and multiple interchangeable anti-static liners  50 A- 50 D each liner structured to inhibit static electricity forming in a corresponding different build material to be held in the container. For example, a shell  48  may be made of high density polyethylene (HDPE) and a liner  50 A may be made of a polyamide for a container  14  to hold a polyamide build material, liner  50 B may be made of a ceramic material for a container  14  to hold a ceramic build material, liner  50 C may be made of a metal for a container  14  to hold a metal build material, and liner  50 D may be made of a composite material for a container  14  to hold a composite build material. Other suitable liner materials may include polypropylene and polyoxymethylene. 
     As noted at the beginning of this Description, the examples shown in the figures and described above illustrate but do not limit the scope of the patent. Other examples are possible. Therefore, the foregoing description should not be construed to limit the scope of the patent, which is defined in the following Claims. 
     “A” and “an” as used in the Claims means one or more.