WO2022231600A1

WO2022231600A1 - Positioning separators in build beds

Info

Publication number: WO2022231600A1
Application number: PCT/US2021/029974
Authority: WO
Inventors: Jorge DIOSDADO BORREGO; Marc GARCIA GRAU
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2021-04-29
Filing date: 2021-04-29
Publication date: 2022-11-03

Abstract

A 3D printer is disclosed herein. The 3D printer comprises a platform feeder to supply a set of build bed separators to a build bed of a build unit, a build material distributor to generate build material layers on a vertically moveable build platform of the build unit, a layer treatment mechanism to selectively treat portions of a build material layer; and a controller. The controller to obtain print job data defining a spatial relationship within the build bed of two vertically separated 3D objects, to determine, based on the print job data, a vertical position within the build bed at which the two 3D objects can be separated into respective vertically independent sub-volumes of the build bed, to control the build material distributor to generate successive build material layers, to control the layer treatment mechanism to selectively treat each of the generated build material layers based on the obtained print job data; and to control the platform feeder to position a separator on the uppermost layer of build material at the determined vertical position.

Description

POSITIONING SEPARATORS IN BUILD BEDS

BACKGROUND

[0001] Some additive manufacturing or three-dimensional printing systems generate 3D objects by selectively solidifying portions of successively formed layers of build material on a layer-by-layer basis. After object generation the build material which has not been solidified is separated from the 3D objects.

BRIEF DESCRIPTION OF THE DRAWINGS [0002] The present application may be more fully appreciated in connection with the following detailed description of non-limiting examples taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout and in which:

[0003] Figure 1 is a schematic front-view diagram showing an example of a 3D printer with a platform feeder;

[0004] Figure 2 is a flowchart of an example method of controlling a platform feeder of a 3D printer;

[0005] Figure 3A is a schematic side view diagram of an example virtual representation of a build bed;

[0006] Figure 3B is a schematic side view diagram of an example build bed with a separator;

[0007] Figure 4 is a flowchart of an example method of controlling functional elements of a 3D printer; and

[0008] Figure 5 is a block diagram showing a processor-based system example to control a platform feeder of a 3D printer.

DETAILED DESCRIPTION

[0009] The following description is directed to various examples of additive manufacturing, or three-dimensional printing, apparatus and processes involved in the generation of 3D objects. Throughout the present disclosure, the terms “a” and “an” are intended to denote at least one of a particular element. In addition, as used herein, the term “includes” means includes but not limited to, the term “including” means including but not limited to. The term “based on” means based at least in part on. [0010] For simplicity, it is to be understood that in the present disclosure, elements with the same reference numerals in different figures may be structurally the same and may perform the same functionality.

[0011] 3D printers generate 3D objects based on data from a 3D object model of an object or objects to be generated, for example, using a CAD computer program product. 3D printers may generate 3D objects by selectively processing layers of build material. For example, a powder-based 3D printer may selectively treat portions of a layer of build material, e.g., a powder, corresponding to a layer of a 3D object to be generated, thereby leaving the portions of the layer un-treated in the areas where no 3D object is to be generated. The combination of the generated 3D objects and the un-treated build material may also be referred to as a build bed.

[0012] Suitable powder-based build materials for use in additive manufacturing include polymer powder, metal powder or ceramic powder. In some examples, non-powdered build materials may be used such as gels, pastes, and slurries. [0013] 3D printers may selectively treat portions of a layer of build material by, for example, ejecting a printing liquid or print agent in a pattern corresponding to cross-sectional slices of the 3D object. Examples of printing liquids may include fusing agents, detailing agents, binder agents or any printing liquid suitable for the generation of a 3D object. Additionally, the chemical composition of some printing liquids may include, for example, a liquid vehicle and/or solvent to be at least partially evaporated once the printing liquid has been applied to the build material layer. For simplicity, the liquid vehicle and/or solvents may be referred hereinafter as solvents. Other 3D printers however, may selectively treat portions of the layer of build material by controlling a focused energy source (e.g., a laser or an array of lasers) to emit energy to the areas of the build material layer which are intended to be solidified. Such printers may include selective laser sintering (SLS) printers and stereolithography printers (SLA).

[0014] Some three-dimensional printing systems use fusing agents to treat the portions of the layer of build material. The portions in which the fusing agent is applied are further heated so that the fusing agent absorbs such energy to heat up and melt, coalesce and solidify upon cooling the portions of build material on which the fusing agent was ejected thereto. The three-dimensional printing system may heat the build material by applying energy from an energy source to each layer of build material.

[0015] Some three-dimensional printing systems use a thermally curable binder agent which has to be heated to a predetermined temperature to cause components of the liquid binder agent to bind together particles of build material on which it is applied. Such a liquid binder agent may comprise latex particles and curing of the binder may occur, for example, at a temperature above 40 degrees Celsius, above 70 degrees Celsius, above 100 degrees Celsius, or above 120 degrees Celsius, or above 150 degrees Celsius.

[0016] Such binder agents may be applied to successive layers of powdered build material, such as powdered stainless steel (e.g., SS316L) build material, and the curing of the binder agent leads to the generation of so-called “green parts.” Green parts are generally relatively low-density objects formed by a matrix of cured binder and metal build material particles. Green parts are transformed into highly dense final objects by heating them in a sintering furnace to a temperature close to the melting point of the build material used.

[0017] After the completion of the green part generation process, the build volume comprises a set of weakly bound green parts surrounded by generally unbound build material. Before green parts are transferred to the sintering oven, the unbound build material has to be separated from the green parts. In some examples, vibration and air-blowing techniques may be used to remove unbound build material. The application of vibration and air blowing techniques cause the green parts to move and/or collide with each other and thereby potentially cause some damage on them.

[0018] To increase efficiency of 3D printers, it is desirable to effectively use as much of the build chamber height as possible. As such it is wanted to generate a plurality of 3D objects stacked vertically on top of each other within the build bed. However, when the 3D objects (or green parts) which are located in the higher layers of objects are separated from the non-treated build material during the decaking process, these 3D objects (or green parts) may fall by to the lower sections of the build bed and get damaged, or damage other 3D printed objects (or green parts) located thereunder. These damaged parts are likely to be discarded. The examples described herein provide a system to allow printing 3D objects on top of each other minimizing the damage of the 3D objects during decaking.

[0019] Figure 1 is a schematic front-view diagram showing an example of a 3D printer 100 with a platform feeder 160.

[0020] The 3D printer 100 comprises a build unit 130 which defines an internal volume in which a build bed 170 is generated. In the examples herein, the build bed 140 comprises the generated 3D printed objects and non-treated build material surrounding them. In some examples, the build unit 130 is an integral element of the 3D printer 110. In other examples, however, the build unit 130 is removable build unit that is removably inserted in the 3D printer 300.

[0021] In some examples, the build unit 130 includes a platform 140. In some examples, the platform 140 is movable vertically within the build unit 130, e.g., downwardly for a distance corresponding to the thickness of each successive build material layer to be generated. Some examples of build material layer thicknesses are 80 microns, 60 microns, 50 microns, 30 microns and 20 microns. Successive layers of build material in which the 3D objects are generated are formed on the build platform 140. In some examples, the 3D printed objects to be generated are green parts. In other examples, the 3D printed objects are not bound green parts but may be, for example, thermally fused polymer-based parts which may be fragile, for example, due to their geometry, thickness, position within the build bed 170, etc.

[0022] The 3D printer 100 comprises a build material distributor 120 to generate build material layers on the vertically moveable build platform 140 or on the uppermost generated build material layer. The build material distributor 120 may comprise a recoating roller, a doctor blade, or an overhead build material dispensing hopper, for instance. In an example, the build material distributor is to move along direction 125.

[0023] The 3D printer 100 further comprises a layer treatment mechanism 110 to treat portions of the generated build material layers. [0024] In one example, the layer treatment mechanism 110 may be implemented as an agent distributor mounted on a carriage to scan over the width and/or the length of the platform 140. The agent distributor 110 may be a printhead, such as a thermal inkjet or piezoelectric printhead, which is controlled to selectively deliver print agent to portions of the uppermost build material layer based on the print job data corresponding to the 3D objects to be printed. Some examples of print agents may comprise, fusing agent, detailing agent, binder agent, colored agents or a combination thereof. In an example, the agent distributor spans the full width of the platform 140 and may scan along the length of the platform 140.

[0025] In another example, the layer treatment mechanism 110 may be a focused energy source or an array of focused energy sources. Some examples may include lasers, laser diodes, VECSELS, or any other suitable energy source capable of selectively treat a portion of a layer of build material based on print job data.

[0026] The 3D printer 100 further comprises a platform feeder 160 to supply a set of build bed separators 165 to the build bed 170 of the build unit 130. The platform feeder 160 may be supplied with a plurality of separators 165 that may be supplied to the build bed 170. In some examples, the separators 165 may be vertically stacked within the platform feeder 160. A separator 165 should be understood as an element comprising a substantially horizontal profile spanning substantially the same surface as the platform 140. The separator 165 is to be placed within a build bed 170 parallel to the build platform 140 to split the build bed into two sub-volumes, a first upper sub-volume located above the separator and a second lower sub-volume located below the separator 165. The platform feeder 160 may supply a separator 165 to the build bed 170 along the direction indicated by arrow 167.

[0027] In some examples, the platform feeder 160 may supply a plurality of separators 165 to a build bed 170. For example, the platform feeder 160 may supply an initial separator directly on the build platform 140. Additionally, or alternatively, the platform feeder 160 may supply a set of separators 165 within the build bed to divide the build bed 170 into multiple sub-volumes. Additionally, in some examples, the separators 165 may comprise apertures of a predetermined size. In one example, these apertures are large enough such that the non-treated build material particles may flow therethrough in a decaking station and small enough such that the 3D generated objects or small geometrical features from the 3D generated objects do not flow or clog the apertures. In yet additional examples, the apertures of the separators 165 that are first introduced to the build bed 170 are larger in size than the apertures of the separators 165 that are later introduced to the build bed 170. This is to allow non-treated build material particles from the upper sub-volumes to flow through the separators into the lower sub-volume of the build bed 170 in a continuous manner.

[0028] The 3D printer 100 further comprises a controller 150. The controller comprises a processor 155 and a memory 157 with specific control instructions stored therein to be executed by the processor. The controller is coupled to the build material distributor 120, the layer treatment mechanism 110, the platform 140 and/or the platform feeder 160. The controller controls at least some of the operations of the elements that it is coupled to. The functionality of the controller is described further below with reference to Figures 2 and 4.

[0029] Figure 2 is a flowchart of a method 200 of controlling a platform feeder 160 of a 3D printer, such as the 3D printer 100 from Figure 1. The method 200 may involve previously disclosed elements from Figure 1 referred to with the same reference numerals. In some examples, parts of method 200 may be executed by a controller, such as controller 150 from the 3D printer 100.

[0030] At block 221 , the controller 150 obtains print job data defining a spatial relationship within the build bed 170 of two 3D objects to be printed vertically separated (i.e. , at non-coinciding vertical positions). In the examples herein, the non-coinciding vertical positions may be understood as meaning objects that do not coincide in any horizontal plane; in other words, a set of vertical positions (i.e., a position along the vertical axis), in which no part of any the 3D objects is to be printed. It is to be understood that in additional examples, the spatial relationship may comprise any number of 3D objects.

[0031] Figure 3A shows a schematic side view diagram 300A of an example virtual representation 330A of a build bed obtained by the controller 150. The virtual representation 330A represents substantially the same build volume as the build bed to be generated, for example build bed 170. The virtual representation 330A comprises a first 3D object 340A and a second 3D object 350B. In some examples, the first and second 3D objects 340A-350A may comprise the same geometry. In other examples, however, the first and second objects 340A-350A may comprise different geometries.

[0032] The first and second 3D objects 340A-350A are spatially arranged within the build volume such that they are separated by a non-zero vertical distance In some examples, the non-zero vertical distance (i.e. , vertical separation region 320A) is at least the thickness of the separator 165, such that the separator 165 can be inserted into the build bed 170. In other examples, the obtained data already takes into account the thickness of the separator 165 at the vertical separation region 320A by removing the number of empty layers that correspond to the thickness of the separator 165.

[0033] In the virtual representation 330A, two 3D objects 340A-350A have been illustrated. However, in other examples, the virtual representation 330A may comprise additional 3D objects. In these examples, a first subset of the plurality of 3D objects may be located above the vertical separation region 320A and a second subset of the plurality of 3D objects may be located below the vertical separation region 320A. Additionally, other examples of virtual representations 330A may comprise the plurality of 3D objects in a set of additional layers of objects, for example 2, 3, 5, 7 or 10 layers of vertically stacked objects separated by respective vertical separation regions.

[0034] Turning back to block 221 of Figure 2 in an example, the controller 150 may receive a plurality of 3D object models (e.g., 350A-B) corresponding to the two 3D objects to be printed and the controller 150 may then determine the spatial relationship within the build bed of the two 3D object models such that the two 3D objects are vertically separated. In another example, however, the controller 150 is to receive print job data defining the spatial relationship within the build bed of the two vertically separated 3D objects.

[0035] At block 222, the controller 150 is to determine, based on the print job data (e.g., virtual representation 330A from Figure 3A), a vertical position within the build bed 170 at which the two 3D objects can be separated into two vertically independent sub-volumes. In some examples, the vertical position may correspond to the vertical separation region 320A from Figure 3A. In other examples, the vertical position may correspond to any position within the vertical separation region between the two 3D objects.

[0036] At block 223, the controller 150 controls the build material distributor 120 to generate successive build material layers. The controller 150 controls the platform 140 to lower by a distance corresponding to the thickness of each build material layer before controlling the build material distributor 120 to generate each build material layer. In some examples, the number and/or the thickness of the build material layers to be generated within a print job may be based on the print job data.

[0037] At block 224, the controller 150 controls the layer treatment mechanism 110 to selectively treat each of the generated build material layers based on the obtained print job data. In the examples herein, the term “selectively treat” may be understood as including selectively ejecting a printing agent to a build material layer, selectively irradiating a portion of a build material layer. In some examples, the layer treatment mechanism 110 may selectively eject a fusing agent and/or a detailing agent based on the obtained print job data print job data. The combination of the generated and treated build material layers (i.e. , blocks 223 and 224) conforms the build bed 170.

[0038] At block 225, the controller 150 is to control the platform feeder 160 to position a separator 165 on the uppermost layer of build material based on the vertical position determined in block 222. In some examples, the controller 150 controls an actuator (e.g., piston, pneumatic cylinder) to move the separator 165 from the platform feeder 160 to the uppermost layer of build material within the print bed 170.

[0039] In some examples, the controller 150 may control the platform feeder 160 to supply an initial separator 165 to the build unit before executing blocks 223 and 224, thereby positioning the initial separator 165 before controlling the build material generator 120 to generate any build material layer. Additionally, in some examples, the platform feeder 160 is to supply the initial separator directly on the build platform 140. As such, the initial separator and the build platform may have similar dimensions, for example, spanning substantially the same surface with respect to the horizontal plane.

[0040] Additionally, the controller 150 is to control the platform feeder 160 to supply the initial separator comprising apertures of a first size and an additional separator 165 comprising apertures of a second different size. In some examples, the apertures of the separators 165 that are first introduced to the build bed 170 (e.g., the initial separator) are larger in size than the apertures of the separators 165 that are later introduced to the build bed 170 (e.g., the additional separator 165) to allow non-treated build material particles from the upper sub-volume to flow through the separators into the lower sub-volume of the build bed 170 in a continuous manner.

[0041] Figure 3B is a schematic side-view diagram 300B of a build unit 330B showing a build bed 370B with a separator 365B. In an example, the build unit 330B may be the build unit 130 from Figure 1 , the build bed 370B may be the build bed 170 from Figure 1 , and the separator 365B may be the separator 165 from Figure 1. In some examples, the build bed 370B may correspond to the generated virtual representation 330A of Figure 3A.

[0042] The schematic diagram 300B shows the separator 365B which has been introduced into the build bed 370B by the platform feeder 160, for example in block 225 from Figure 2. The separator 365B separates the build bed 370B in an upper sub-volume above the separator 365B and a lower sub-volume below the separator 365B. A first 3D printed object 340B is generated in the lower sub volume as defined in the first virtual object model 340A of the virtual representation 330A from Figure 3A, and a second 3D printed object 350B is generated in the upper sub-volume as defined in the second virtual object model 350A of the virtual representation 330A from Figure 3A. The first and second 3D printed objects 340B-350B have been generated by generating build material layers (e.g., block 223) and selectively treating the build material layers based on the virtual representation model 340A (e.g., block 224).

[0043] Figure 4 is a flowchart of an example method 400 of controlling functional elements of a 3D printer, such as 3D printer 100 from Figure 1. The method 400 may involve previously disclosed elements from Figure 1 referred to with the same reference numerals. Method 400 may start after the separator 165 has been positioned (i.e., block 225) at the determined vertical position (i.e. , block 222). In some examples, method 400 may be executed by a controller, such as controller 150 from the 3D printer 100, after the executing of block 225 of method 200 of Figure 2.

[0044] At block 423, the controller 150 controls the build material distributor 120 to generate additional successive build material layers. The controller 150 may execute block 423 in a similar manner as block 223 from method 200 but above the separator 165.

[0045] At block 424, the controller 150 controls the layer treatment mechanism 110 to selectively treat each of the generated successive build material layers (i.e., block 423) based on the obtained print job data (i.e., block 221 ). In some examples, blocks 423 and 424 may be executed sequentially and in an iterative manner until the completion of the print job or upon the positioning of an additional separator (e.g., block 225). The combination of block 423 and 424 may generate the second upper sub-volume as defined in the examples above with respect to Figure 3B.

[0046] Figure 5 is a block diagram showing a processor-based system 500 example to control a platform feeder within a 3D printer, for example the platform feeder 160 of 3D printer 100. In the examples herein, the instructions of system 500 may involve previously disclosed elements from Figure 1 referred to with the same reference numerals.

[0047] In some implementations, the system 500 is a processor-based system and may include a processor 510 coupled to a machine-readable medium 520. [0048] The machine-readable medium 520 may be any medium suitable for storing executable instructions, such as a random-access memory (RAM), electrically erasable programmable read-only memory (EEPROM), flash memory, hard disk drives, optical disks, and the like. In some example implementations, the machine-readable medium 520 may be a tangible, non-transitory medium, where the term “non-transitory” does not encompass transitory propagating signals. The machine-readable medium 520 may be disposed within the processor-based system 500, as shown in Figure 5, in which case the executable instructions may be deemed “installed” on the system 500. Alternatively, the machine-readable medium 520 may be a portable (e.g., external) storage medium, for example, that allows system 500 to remotely execute the instructions or download the instructions from the storage medium. In this case, the executable instructions may be part of an “installation package.” As described further herein below, the machine-readable medium may be encoded with a set of executable instructions 521-525.

[0049] Instructions 521 , when executed by the processor 510, may cause the processor 510 to obtain a print job defining a spatial relationship of a plurality of 3D objects to be printed vertically separated within a build bed 130 of a 3D printer 100. The vertical position is defined such that a first subset of the plurality of 3D objects are printed above the vertical position and a second subset of the plurality of 3D objects are printed below the vertical position.

[0050] Instructions 522, when executed by the processor 510, cause the processor 510 to determine, based on the print job, the vertical position within the build bed 130 according to the examples set out above.

[0051] Instructions 523, when executed by the processor 510, cause the processor 510 to generate build material layers up to the vertical positions; and instructions 524, when executed by the processor 510, cause the processor 510 to selectively deliver print agent as the build material layers are generated based on the print job data.

[0052] Instructions 525, when executed by the processor 510, cause the processor 510 to position, using the platform feeder 160, a separator 165 on the uppermost layer of build material based on the determined vertical position, as described above.

[0053] The above examples may be implemented by hardware, or software in combination with hardware. For example, the various methods, processes and functional modules described herein may be implemented by a physical processor (the term processor is to be implemented broadly to include CPU, SoC, processing module, ASIC, logic module, or programmable gate array, etc.). The processes, methods and functional modules may all be performed by a single processor or split between several processors; reference in this disclosure or the claims to a “processor” should thus be interpreted to mean “at least one processor.” The processes, method and functional modules are implemented as machine-readable instructions executable by at least one processor, hardware logic circuitry of the at least one processor, or a combination thereof.

[0054] The drawings in the examples of the present disclosure are some examples. It should be noted that some units and functions of the procedure may be combined into one unit or further divided into multiple sub-units. What has been described and illustrated herein is an example of the disclosure along with some of its variations. The terms, descriptions and figures used herein are set forth by way of illustration. Many variations are possible within the scope of the disclosure, which is intended to be defined by the following claims and their equivalents.

[0055] There have been described example implementations with the following sets of features:

[0056] Feature set 1 : A 3D printer comprising: a platform feeder to supply a set of build bed separators to a build bed of a build unit; a build material distributor to generate build material layers on a vertically moveable build platform of the build unit; a layer treatment mechanism to selectively treat portions of a build material layer; and a controller to: obtain print job data defining a spatial relationship within the build bed of two vertically separated 3D objects; determine, based on the print job data, a vertical position within the build bed at which the two 3D objects can be separated into two vertically independent sub-volumes; control the build material distributor to generate successive build material layers; control the layer treatment mechanism to selectively treat each of the generated build material layers based on the obtained print job data; and control the platform feeder to position a separator on the uppermost layer of build material based on the determined vertical position. [0057] Feature set 2: A 3D printer with feature set 1 , wherein the controller is to control the platform feeder to supply an initial separator to the build unit before controlling the build material distributor to generate any build material layer. [0058] Feature set 3: A 3D printer with any preceding feature set 1 to 2, wherein the controller is to control the platform feeder to supply the initial separator directly on the build platform.

[0059] Feature set 4: A 3D printer with any preceding feature set 1 to 3, wherein the controller is to determine that the vertical position at which the separator is to be positioned corresponds to a vertical gap between the two 3D objects.

[0060] Feature set 5: A 3D printer with any preceding feature set 1 to 4, wherein upon positioning the separator on the determined vertical position, the controller is further to: control the build material distributor to generate additional successive build material layers; and control the layer treatment mechanism to selectively treat each of the generated additional successive build material layers based on the obtained print job data.

[0061] Feature set 6: A 3D printer with any preceding feature set 1 to 5, wherein the platform feeder is to supply an initial separator comprising apertures of a first size and an additional separator comprising apertures of a second different size. [0062] Feature set 7: A 3D printer with any preceding feature set 1 to 6, wherein the first size is larger than the second size.

[0063] Feature set 8: A 3D printer with any preceding feature set 1 to 7, wherein the layer treatment mechanism is an agent delivery mechanism to selectively deliver a print agent to portions of the uppermost build material layer, and the controller to: control the agent delivery mechanism to selectively deliver the print agent to each of the generated build material layers based on the obtained print job data.

[0064] Feature set 9: A 3D printer with any preceding feature set 1 to 8, wherein the controller is to: receive a plurality of 3D object models corresponding to the two 3D objects to be printed; and determining a spatial relationship within the build bed of the two 3D object models such that the two 3D objects are vertically separated.

[0065] Feature set 10: A 3D printer with any preceding feature set 1 to 9, wherein the controller is to receive the print job data defining a spatial relationship within the build bed of two 3D objects to be printed vertically separated.

[0066] Feature set 11 : A method comprising: obtaining a print job defining a spatial relationship of a plurality of 3D objects to be printed at a non-coinciding vertical position to be generated within a build bed of a 3D printer, the vertical position being defined such that a first subset of the plurality of 3D objects are printed above the vertical position and a second subset of the plurality of 3D objects are printed below the vertical position; determining, based on the print job, the vertical position within the build bed; generating build material layers up to the vertical position; selectively treating the build material layers based on the print job, as the layers are generated; and positioning, through a platform feeder, a separator on the uppermost layer of build material based on the determined vertical position.

[0067] Feature set 12: A method with preceding feature set 11 , wherein upon positioning the separator on the determined vertical position, the method further comprising: generating additional successive build material layers; and selectively treating each of the generated additional successive build material layers based on the print job.

[0068] Feature set 13: A method with any preceding feature set 11 to 12, wherein treating the build material layers comprises delivering a print agent to each of the generated build material layers based on the obtained print job data. [0069] Feature set 14: A method with any preceding feature set 11 to 13, further comprising: receiving a plurality of 3D object models corresponding to the plurality of 3D objects to be printed; and determining a spatial relationship within the build bed of the plurality 3D object models such that the plurality of 3D objects are located above and below the non-coinciding vertical position. [0070] Feature set 15: A non-transitory machine-readable medium storing instructions executable by a processor, the non-transitory machine-readable medium comprising: instructions to obtain a print job defining a spatial relationship of a plurality of 3D objects to be printed vertically separated within a build bed of a 3D printer, the vertical position being defined such that a first subset of the plurality of 3D objects are printed above the vertical position and a second subset of the plurality of 3D objects are printed below the vertical position; instructions to determine, based on the print job, the vertical position within the build bed; instructions to generate build material layers up to the vertical position; instructions to selectively deliver print agent as the build material layers are generated based on the print job data; and instructions to position, through a platform feeder, a separator on the uppermost layer of build material based on the determined vertical position.

Claims

CLAIMS WHAT IT IS CLAIMED IS:

1. A 3D printer comprising: a platform feeder to supply a set of build bed separators to a build bed of a build unit; a build material distributor to generate build material layers on a vertically moveable build platform of the build unit; a layer treatment mechanism to selectively treat portions of a build material layer; and a controller to: obtain print job data defining a spatial relationship within the build bed of two vertically separated 3D objects; determine, based on the print job data, a vertical position within the build bed at which the two 3D objects can be separated into respective vertically independent sub-volumes of the build bed; control the build material distributor to generate successive build material layers; control the layer treatment mechanism to selectively treat each of the generated build material layers based on the obtained print job data; and control the platform feeder to position a separator on the uppermost layer of build material at the determined vertical position.

2. The 3D printer of claim 1 , wherein the controller is to control the platform feeder to supply an initial separator to the build unit before controlling the build material distributor to generate any build material layer.

3. The 3D printer of claim 2, wherein the controller is to control the platform feeder to supply the initial separator directly on the build platform.

4. The 3D printer of claim 1, wherein the controller is to determine that the vertical position at which the separator is to be positioned corresponds to a vertical separation region between the two 3D objects.

5. The 3D printer of claim 1 , wherein upon positioning the separator on the determined vertical position, the controller is further to: control the build material distributor to generate additional successive build material layers; and control the layer treatment mechanism to selectively treat each of the generated additional successive build material layers based on the obtained print job data.

6. The 3D printer of claim 1 , wherein the platform feeder is to supply an initial separator comprising apertures of a first size and an additional separator comprising apertures of a second different size.

7. The 3D printer of claim 6, wherein the first size is larger than the second size.

8. The 3D printer of claim 1 , wherein the layer treatment mechanism is an agent delivery mechanism to selectively deliver a print agent to portions of the uppermost build material layer, and the controller to: control the agent delivery mechanism to selectively deliver the print agent to each of the generated build material layers based on the obtained print job data.

9. The 3D printer of claim 1 , wherein the controller is to: receive a plurality of 3D object models corresponding to the two 3D objects to be printed; and determining a spatial relationship within the build bed of the two 3D object models such that the two 3D objects are vertically separated.

10. The 3D printer of claim 1 , wherein the controller is to receive the print job data defining a spatial relationship within the build bed of two 3D objects to be printed vertically separated.

11. A method comprising: obtaining a print job defining a spatial relationship of a plurality of 3D objects to be printed at a non-coinciding vertical position to be generated within a build bed of a 3D printer, the vertical position being defined such that a first subset of the plurality of 3D objects are printed above the vertical position and a second subset of the plurality of 3D objects are printed below the vertical position; determining, based on the print job, the vertical position within the build bed; generating build material layers up to the vertical position; selectively treating the build material layers based on the print job, as the layers are generated; and positioning, through a platform feeder, a separator on the uppermost layer of build material based on the determined vertical position.

12. The method of claim 11, wherein upon positioning the separator on the determined vertical position, the method further comprising: generating additional successive build material layers; and selectively treating each of the generated additional successive build material layers based on the print job.

13. The method of claim 11, wherein treating the build material layers comprises delivering a print agent to each of the generated build material layers based on the obtained print job data.

14. The method of claim 11 , further comprising: receiving a plurality of 3D object models corresponding to the plurality of 3D objects to be printed; and determining a spatial relationship within the build bed of the plurality 3D object models such that the plurality of 3D objects are located above and below the non-coinciding vertical position.

15. A non-transitory machine-readable medium storing instructions executable by a processor, the non-transitory machine-readable medium comprising: instructions to obtain a print job defining a spatial relationship of a plurality of 3D objects to be printed vertically separated within a build bed of a 3D printer, the vertical position being defined such that a first subset of the plurality of 3D objects are printed above the vertical position and a second subset of the plurality of 3D objects are printed below the vertical position; instructions to determine, based on the print job, the vertical position within the build bed; instructions to generate build material layers up to the vertical position; instructions to selectively deliver print agent as the build material layers are generated based on the print job data; and instructions to position, through a platform feeder, a separator on the uppermost layer of build material based on the determined vertical position.