Patent Publication Number: US-11654626-B2

Title: Additive manufacturing

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This is a divisional of U.S. application Ser. No. 16/075,430, filed Aug. 3, 2018, which itself is a U.S. national stage under 35 U.S.C. § 371 of international application no. PCT/US2016/057730, filed Oct. 19, 2016, each of which is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Additive manufacturing machines produce 3D 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  and  2    are elevation and plan views, respectively, illustrating one example of a fusing system for an additive manufacturing machine. 
         FIGS.  3 - 26    present a sequence of views showing one example of a four pass fusing cycle using the fusing system of  FIGS.  1  and  2   . 
         FIG.  27    is a flow diagram illustrating one example of a process for additive manufacturing, such as might be implemented with the fusing system of  FIGS.  1  and  2   . 
         FIG.  28    is a block diagram illustrating one example of a processor readable medium with instructions thereon to help form an object slice during additive manufacturing a 3D object. 
         FIG.  29    is a block diagram illustrating one example of an additive manufacturing machine implementing a controller with instructions to help form an object slice during additive manufacturing a 3D object. 
     
    
    
     The same part numbers designate the same or similar parts throughout the figures. The figures are not to scale. 
     DESCRIPTION 
     In some additive manufacturing processes, heat is used to fuse together the particles in a powdered build material to form a solid object. Heat to fuse the build material may be generated, for example, by applying a liquid fusing agent to a thin layer of powdered build material in a pattern based on the object slice and then exposing the patterned area to fusing light. Light absorbing components in the fusing agent absorb light energy to help sinter, melt or otherwise fuse the build material. The process is repeated layer by layer and slice by slice to complete the object. 
     A new fusing system has been developed for additive manufacturing to help speed the formation of each object slice, and thus reduce overall manufacturing times, while lowering powder temperatures for faster cooling and less caking. In one example, the fusing system includes two carriages that move back and forth over the work area along the same line of motion so that one carriage can follow the other carriage across the work area. A “fuser” carriage carries a layering device to layer build material over the work area, a heating lamp to heat layered build material, and a fusing lamp to irradiate build material with fusing light. The heating lamp is positioned on the fuser carriage downstream from the layering device (in the layering direction). The fusing lamp is positioned downstream from the heating lamp. A “dispenser” carriage carries the agent dispenser to dispense a fusing agent on to each layer of build material. 
     A dual carriage fusing system in which the carriages move along the same line of motion helps enable faster slew speeds and overlapping functions in each pass. For example, in a first pass, as the fuser carriage moves over the work area, the heating lamp is on to heat the underlying layer/slice in front of the layering device as the layering device forms the next layer of build material. In a second pass, as the fuser carriage moves back over the work area, the heating lamp is on to heat the new layer of build material in advance of the dispenser carriage, which follows the fuser carriage over the work area to dispense fusing and/or detailing agents on to the heated build material in a pattern based on the next object slice. In a third pass, the dispenser carriage moves back over the work area to dispense fusing and/or detailing agents on to the build material, followed by the fuser carriage with the fusing lamp on to expose patterned build material to fusing light. In a fourth pass, as the fuser carriage moves back over the work area, the fusing light is on to expose patterned build material to fusing light. The four pass process may be repeated for successive layers of build material as the object is manufactured layer by layer and slice by slice. 
     These and other examples described below 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; a “fusing agent” means a substance that causes or helps cause a build material to sinter, melt or otherwise fuse; a “detailing agent” means a substance that inhibits or prevents or enhances fusing a build material, for example by modifying the effect of a fusing agent; “light” means electromagnetic radiation of any wavelength; a “lamp” means any device that emits light; and “work area” means any suitable structure to support or contain build material for fusing, including underlying layers of build material and in-process slice and other object structures. 
       FIGS.  1  and  2    are elevation and plan views, respectively, illustrating one example of a fusing system  10  for an additive manufacturing machine.  FIGS.  3 - 26    present a sequence of views showing one example of a four pass fusing cycle using system  10 . Referring first to  FIGS.  1  and  2   , fusing system  10  includes a first, “fuser” carriage  12  and a second, “dispenser” carriage  14 . Carriages  12  and  14  move back and forth, for example on rails  16 , over a work area  18  along a line of motion  20 . Fuser carriage  12  carries a layering device  22 , a heater  24 , and a fusing lamp  26 . Dispenser carriage  14  carries an inkjet printhead assembly or other suitable fluid dispensing assembly  28  to dispense a fluid fusing agent. In the example shown, dispensing assembly  28  includes a first dispenser  30  to dispense a fusing agent and a second dispenser  32  to dispense a detailing agent. 
     In the example shown in  FIGS.  1  and  2   , layering device  22  is implemented as a roller  22  that moves between a deployed position (shown in  FIG.  3   ) to layer build material as carriage  12  moves over work area  18  and a retracted position (shown in  FIG.  1   ) to not layer build material as carriage  12  moves over work area  18 . Layering roller  22  may rotate freely as it is moved over work area  18 , freewheeling clockwise or counter-clockwise depending on the direction of travel, or roller  22  may be driven rotationally in either direction (co-rotated or counter-rotated). Other implementations for a layering device  22  are possible including, for example, a blade or a device that dispenses build material directly over the work area in a layer. 
     Heater  24  may be implemented as a heating lamp  24 , for example. Although a single heating lamp  24  is depicted, multiple heating lamps may be used, for example to enable more versatile heating. Similarly, although a single fusing lamp  26  is depicted, multiple fusing lamps may be used, for example to enable a greater range of fusing light. While the characteristics of heating lamp  24  and fusing lamp  26  may vary depending on characteristics of the build material and fusing agent (and other process parameters), it is expected that a lower color temperature heating lamp  24  and a higher color temperature fusing lamp  26  usually will be desirable to better match the spectral absorption of the untreated and treated build material, respectively. For example, for a white polyamide powdered build material  38  and a black liquid fusing agent, an 1800° K heating lamp  24  may be used to pre-heat the untreated build material powder and a 2750° K fusing lamp used for greater power transfer to build material treated with fusing agent and less to the untreated powder. 
     As noted above, work area  18  represents any suitable structure to support or contain build material for fusing, including underlying layers of build material and in-process slice and other object structures. For a first layer of build material, for example, work area  18  may be formed on the surface of a platform  34  that moves up and down to accommodate the layering process. For succeeding layers of build material, for example as shown in  FIG.  1   , work area  18  may be formed on an underlying object structure  36 , which may include unfused build material  38  and build material that has been fused into an object slice  40 . 
     In  FIGS.  1  and  2   , fuser carriage  12  is parked on one side  42  of work area  18  (the left side in  FIGS.  1  and  2   ) and dispenser carriage  14  is parked on the other side  44  of work area  18  (the right side in  FIGS.  1  and  2   ). In this example, a ribbon  46  of build material powder  38  has been deposited along a left side deck  48  adjacent to work area  18 . In  FIGS.  3  and  4   , layering roller  22  is deployed, heating lamp  24  is turned on to heat the powder in ribbon  46  and fuser carriage  12  is moving to the right in a first pass, as indicated by motion arrows  50 . In  FIGS.  5  and  6   , as fuser carriage  12  continues moving to the right in the first pass, heating lamp  24  heats underlying object structure  36  while roller  22  layers build material  38  in a layer  52  over underlying structure  36 . Although a powdered build material  38  is depicted by stippling in the figures, any suitable build material may be used. 
     In  FIGS.  7  and  8   , fuser carriage  12  has reached the right side of work area  18  after covering underlying structure  36  with layer  52 . In the example shown in  FIGS.  7  and  8   , layering roller  22  has been retracted to jump over a strip  54  of excess build material  38  on right deck  55  in preparation for re-layering the excess build material in a second pass. In  FIGS.  9 - 10  and  11 - 12   , as fuser carriage  12  moves to the left in a second pass, indicated by motion arrows  56 , layering roller  22  is deployed to re-layer excess build material in layer  52  and heating lamp  24  is turned on to heat build material  38  in layer  52 . Also in the second pass, dispenser  30  on dispenser carriage  14  following fuser carriage  12  dispenses a fusing agent  58  on to build material  38  in layer  52  in a pattern  60  corresponding to the desired object slice. 
     In  FIGS.  13  and  14   , fuser carriage  12  and dispenser carriage  14  have reached the left side of work area  18  after patterning build material  38  in layer  52  with fusing agent  58 . In  FIGS.  15 - 16  and  17 - 18   , as dispenser carriage  14  moves to the right in a third pass, indicated by motion arrows  62 , dispenser  32  dispenses a detailing agent  64  on to build material  38  in layer  52 . Also in the third pass, fusing lamp  26  is turned on to irradiate patterned build material  60  with fusing light to fuse or begin to fuse patterned build material into an object slice  66 . 
     In  FIGS.  19  and  20   , fuser carriage  12  and dispenser carriage  14  have reached the right side of work area  18  after forming slice  66  in build material layer  52 . In  FIGS.  21  and  22   , dispenser carriage  14  remains parked while fuser carriage  12  moves to the left in a fourth pass, indicated by motion arrows  68 , with fusing lamp  26  turned on to irradiate patterned build material  60  including slice  66 . Depending on the degree of fusing in the third pass (shown in  FIGS.  17    and  18 ), the fusing light applied in the fourth pass may complete slice  66  as depicted in  FIGS.  19  and  20    or further fuse patterned build material  60  toward completion of slice  66 , for example in advance of the first (next) pass with fusing lamp  26  turned on to irradiate slice  66  with more fusing light as shown in  FIG.  25   . 
     In  FIGS.  23  and  24   , fuser carriage  12  is parked on the left side of work area  18  after the fourth pass, dispenser carriage  14  is still parked on the right side of work area  18 , and a ribbon  46  of build material has been dispensed to deck  48  in preparation for forming the next layer of build material over work area  18 . In  FIGS.  25  and  26   , as fuser carriage  12  is moving to the right, fusing lamp  26  is turned on to irradiate slice  66  with fusing light, heating lamp  24  is turned on to heat the new underlying object structure  72  while roller  22  layers build material  38  in the next layer  74  over underlying structure  72 . 
     The sequence of operations may continue for each succeeding layer of build material, slice by slice, to complete the object. 
     Other processing and system configurations are possible. For example, where an UV (ultraviolet) fusing lamp  26  is used with a UV curable fusing agent  58  to fuse build material  38 , a heating lamp  24  may be omitted. For another example, layering roller  22  could be retracted throughout the second pass ( FIGS.  9  and  10   ), such as when re-layering build material is not desired and/or to help protect dispensers  30 ,  32  against contamination by airborne dust from a powdered build material. More or fewer agent dispensers are possible to dispense more or fewer agents. Also, the sequence of dispensing fusing and detailing agents may vary from that shown. 
       FIG.  27    illustrates one example of a process  100  for additive manufacturing, such as might be implemented with a fusing system  10  shown in  FIGS.  1  and  2   . Referring to  FIG.  27   , in a first carriage pass, an in-process object structure is irradiated and then a layer of build material is formed over the object structure (block  102 ), for example as described above with reference to  FIGS.  3 - 6   . In a second carriage pass, build material in the layer is irradiated and then a fusing agent and/or a detailing agent is dispensed on to build material in the layer (block  104 ), for example as described above with reference to  FIGS.  9 - 12   . In a third carriage pass, a fusing agent and/or a detailing agent is dispensed on to build material in the layer and then build material in the layer is irradiated (block  106 ), for example as described above with reference to  FIGS.  15 - 18   . In a fourth carriage pass, build material in the layer is irradiated (block  108 ), for example as described above with reference to  FIGS.  21  and  22   . 
       FIG.  28    is a block diagram illustrating a processor readable medium  76  with instructions  78  to help form an object slice during the manufacture of a 3D object. 
     In one example, slice forming instructions  78  include instructions to: 
     in a first pass over a work area, apply fusing energy to build material in a first layer of build material treated with a fusing agent, then heat untreated build material in the first layer of build material, and then cover the first layer of build material with a second layer of build material, for example as described above with reference to  FIGS.  25  and  26   ; 
     in a second pass over the work area, heat build material in the second layer and then treat heated build material in the second layer with a fusing agent and/or a detailing agent, for example as described above with reference to  FIGS.  9 - 12   ; 
     in a third pass over the work area, treat build material in the second layer with a fusing agent and/or a detailing agent and then apply fusing energy to treated build material in the second layer, for example as described above with reference to  FIGS.  15 - 18   ; and then in a fourth pass over the work area, apply fusing energy to treated build material in the second layer, for example as described above with reference to  FIGS.  21  and  22   . 
     In another example, slice forming instructions  78  in  FIG.  28    includes instructions to execute the process illustrated in  FIG.  27   . 
     Processor readable medium  76  with slice forming instructions  78  may be implemented, for example, in a CAD computer program product, in an object model processor, or in a controller for an additive manufacturing machine. Control data to form a slice in a four pass sequence such as that shown in  FIGS.  1 - 26    may be generated, for example, by processor readable instructions on the source application, usually a CAD computer program product, in an object model processor, or by processor readable instructions on the additive manufacturing machine. 
       FIG.  29    is a block diagram illustrating one example of an additive manufacturing machine  80  implementing a controller  82  with slice forming instructions  78 . Referring to  FIG.  29   , machine  80  includes controller  82 , a work area  18 , a build material layering device  84 , a fusing agent dispenser  30 , a detailing agent dispenser  32 , a heater  24  and a fusing lamp  26 . Build material layering device  84  layers build material over work area  18  and may include, for example, a device to dispense the build material and a blade or roller  22  to spread the build material for each layer. Fusing agent dispenser  30  and detailing agent dispenser  32  dispense their respective agents selectively at the direction of controller  82 , for example as described above with reference to  FIGS.  11 - 12  and  15 - 16   . While any suitable dispensers  30 ,  32  may be used, inkjet printheads are sometimes used in additive manufacturing machines because of the precision with which they can dispense agents and their flexibility to dispense different types and formulations of agents. 
     Controller  82  represents the processor (or multiple processors), the associated memory (or multiple memories) and instructions, and the electronic circuitry and components needed to control the operative elements of machine  80 . In particular, controller  82  includes a processor readable medium  76  with slice forming instructions  78  and a processor  86  to read and execute instructions  78 . 
     The examples shown in the figures and described above illustrate but do not limit the patent, which is defined in the following Claims. 
     “A”, “an” and “the” used in the claims means at least one. For example, “a fusing lamp” means one or more fusing lamps and subsequent reference to “the fusing lamp” means the one or more fusing lamps.