GB2550341A

GB2550341A - Build Material Distributor Cleaning Element

Info

Publication number: GB2550341A
Application number: GB1608370.1A
Authority: GB
Inventors: Gimenez Jordi; Gomez Francisco; Mosquera Gerard
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2016-05-12
Filing date: 2016-05-12
Publication date: 2017-11-22
Also published as: GB201608370D0

Abstract

An apparatus 100 for generating a three-dimensional object comprises a build material distributor 110 coupled to a scanning carriage 108; the build material distributor to distribute build material in the build area and movable to a cleaning location; and a cleaning subsystem 120 comprising at least one cleaning element 122 located in the cleaning location wherein the cleaning element engages the build material distributor to remove build material therefrom. Preferably, the build material distributor is rotatable, such as a roller. The cleaning element may be rotatable (156, fig 4) wherein the build material distributor rotates in a first rotational direction (158, fig 4) and the cleaning element rotates in a second counter rotational direction (160, fig 4) when engaged with the build material distributor. The cleaning element may comprise a wiping element, rotatable cleaning element, brush, air blower or any combination thereof. A controller may be provided to determine whether to clean the build material distributor and control the scanning carriage to the cleaning location.

Description

BUILD MATERIAL DISTRIBUTOR CLEANING ELEMENT

BACKGROUND

[0001 ] Additive manufacturing systems that generate three-dimensional objects on a layer-by-layer basis are convenient way for producing three-dimensional objects. Examples of additive manufacturing systems include three-dimensional printing systems. The quality of objects produced by additive manufacturing systems may vary widely based on the type of additive manufacturing technology used.

DRAWINGS

[0002] FIG. 1 provides a block diagram of some components of an example apparatus for generating three-dimensional objects.

[0003] FIG. 2 provides a block diagrams of some components of an example apparatus for generating three-dimensional objects.

[0004] FIG. 3 provides a block diagram of some components of an example apparatus for generating three-dimensional objects.

[0005] FIG. 4 provides a block diagram of some components of an example apparatus for generating three-dimensional objects.

[0006] FIG. 5 provides a block diagram of some components of an example apparatus for generating three-dimensional objects.

[0007] FIG. 6 provides a block diagram of some components of an example apparatus for generating three-dimensional objects.

[0008] FIG. 7 provides a flowchart that illustrates a sequence of operations that may be performed by an example apparatus.

[0009] FIG. 8 provides a flowchart that illustrates a sequence of operations that may be performed by an example apparatus.

[0010] FIG. 9 provides a flowchart that illustrates a sequence of operations that may be performed by an example apparatus.

[0011 ] FIG. 10 provides a flowchart that illustrates a sequence of operations that may be performed by an example apparatus.

[0012] FIG. 11 provides a flowchart that illustrates a sequence of operations that may be performed by an example apparatus.

[0013] FIG. 12 provides a flowchart that illustrates a sequence of operations that may be performed by an example apparatus.

[0014] Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.

DESCRIPTION

[0015] Examples provided herein include apparatuses, processes, and methods for generating three-dimensional objects. Apparatuses for generating three-dimensional objects may be referred to as additive manufacturing apparatuses. As will be appreciated, example apparatuses described herein may correspond to three-dimensional printing systems, which may also be referred to as three-dimensional printers. In an example additive manufacturing process, a layer of build material may be distributed in a build area, a fusing agent may be selectively distributed on the layer of build material, and fusing energy may be temporarily applied to the layer of build material. As used herein, a build layer may refer to a layer of build material distributed in a build area upon which agent may be distributed and/or energy may be applied.

[0016] The application of energy may cause portions of the layer of build material to which fusing agent has been applied to coalesce or fuse. In contrast, build material upon which agent was not distributed may not coalesce or fuse due to the application of energy. In some examples, energy may be applied to a build layer with at least one energy source of an example apparatus. Examples of energy sources may comprise a heating element, electromagnetic radiation emitter (e.g., light emitter, infrared emitter, ultraviolet emitter, laser emitter, etc.), and/or a lamp (e.g., a halogen lamp).

[0017] The temperature at which portions of the layer of build material may begin to coalesce or fuse may be referred to as a fusing temperature.

Upon cooling, portions of the build material layer that have coalesced become solid and form part of a three-dimensional object being generated. Accordingly, the portions of the build material layer upon which agent is selectively distributed (and which become solid) may be referred to as the “part area” of the build layer.

[0018] Additional layers may be formed and the operations described above may be performed for each layer to thereby generate a three-dimensional object. As will be appreciated, a part area of each layer may correspond to a cross-section of a three-dimensional object to be formed. Sequentially layering and fusing portions of layers of build material on top of previous layers may facilitate generation of the three-dimensional object. The layer-by-layer formation of a three-dimensional object may be referred to as a layer-wise additive manufacturing process. In some examples, a height of a build layer (which may also be referred to as thickness) may be in the micron scale. For example, some example build layer heights may be in the range of approximately 60 to approximately 150 microns. Furthermore, an overall build height of the cumulative layers of build material may be in the centimeter or meter scale depending on the apparatus and process implemented.

[0019] In examples described herein, a build material may include a powder-based build material, where powder-based build material may comprise wet and/or dry powder-based materials, particulate materials, and/or granular materials. In some examples, the build material may be a weak light absorbing polymer. In some examples, the build material may be a thermoplastic. Furthermore, as described herein, agent may comprise fluids that may facilitate fusing of build material when energy is applied. In some examples, agent may be referred to as coalescing or fusing agent. In some examples, agent may be a light absorbing liquid, an infrared or near infrared absorbing liquid, such as a pigment colorant.

[0020] As will be appreciated, various types of build materials may have differing material properties. Performance of various operations of a layer-wise additive manufacturing process as described herein may be based at least in part on material properties of a build material used in such process. Example material properties may include critical temperature (e.g., a temperature corresponding to a critical point that is an end point of a phase equilibrium), emissivity, absorbance, thermal conductivity, thermal diffusivity, thermal expansion, photosensitivity, reflectivity, melting point, coefficient of thermal expansion, plasticity, elasticity, permeability, reactivity, surface energy, electrical conductivity, permittivity, and/or other such material properties.

[0021] In some examples, an apparatus may comprise, or may receive, a build material support, where a surface of the build material support may correspond to a build area. Accordingly, a starting layer of build material may be distributed on the surface of the build material support in the build area. Subsequent layers of build material may be formed in the build area on previously formed and processed layers. Furthermore, apparatuses may comprise energy sources with which to temporarily apply energy to build material layers to heat the build material layers to thereby pre-fuse and/or fuse the build material layers. For example, an apparatus may comprise at least one energy source that may heat a build material layer such that portions of the build material layer where agent has been distributed may fuse. In some examples, apparatuses may further comprise additional energy sources with which to preheat build material layers.

[0022] In addition, example apparatus may comprise an agent distributor. In some examples, an agent distributor may comprise a printhead or printheads (e.g., a thermal ejection based printhead, a piezoelectric ejection based printhead, etc.). An agent distributor may be coupled to a scanning carriage, and the scanning carriage may move along a scanning axis over the build area. In one example, printheads suitable for implementation in commercially available inkjet printing devices may be implemented as an agent distributor. In other examples, an agent distributor may comprise other types of fluid ejection devices that selectively eject small volumes of fluid. In some examples, an agent distributor may comprise at least one printhead that comprises a plurality of fluid ejection dies arranged generally end-to-end along a width of the agent distributor. In some examples, the at least one printhead may comprise a plurality of printheads arranged generally end-to-end along a width of the agent distributor. In such examples, a width of the agent distributor may correspond to a dimension of a build area. For example, a width of the agent distributor may correspond to a width of a build area. As will be appreciated, an agent distributor may selectively distribute agent on a build layer in the build area concurrent with movement of the scanning carriage over the build area.

[0023] In some examples, apparatuses may comprise a build material distributor to distribute build material in the build area. A build material distributor may comprise, for example, a wiper blade, a roller, and/or a spray mechanism. In some examples, a build material distributor may be coupled to a scanning carriage. In these examples, the build material distributor may distribute build material in the build area as the scanning carriage moves over the build area along the scanning axis to thereby distribute a layer of build material in the build area.

[0024] In some example additive manufacturing processes, residual build material may remain on a build material distributor after formation of a build layer in a build area. For example, some apparatuses pre-heat build material prior to distribution, and pre-heating of the build material may cause some build material to stick or temporarily adhere to a surface of a build material distributor. As will be appreciated, as the build material temporarily adheres to the build material distributor, additional build material may accumulate on the build material distributor during use. In addition, as discussed previously, various types of build materials having various material properties may be used in apparatuses and processes described herein. Accordingly, due to material properties some example build materials may adhere to a build material distributor more than other example build materials. In such examples, residual build material attached/adhered to a build material distributor may reduce build material distribution uniformity in layers of build material in the build area. In turn, build material adherence to a build material distributor may reduce dimensional accuracy of an object generated by an example apparatus according to an example process.

[0025] Example apparatuses for generating a three-dimensional object described herein may comprise a cleaning element disposed at a cleaning location of the apparatus. In some examples, a cleaning subsystem that comprises at least one cleaning element may be disposed at a cleaning location of the apparatus that is spaced apart from a build area of the apparatus. In such examples, a build material distributor may be moved to the cleaning location, and at least one cleaning element disposed at the cleaning location may engage the build material distributor. In examples described herein, the at least one cleaning element may be used to remove build material from the build material distributor to thereby clean the build material distributor of residual build material that is temporarily adhered to the build material distributor.

[0026] In some examples, while positioned at the cleaning location, the build material distributor may be rotated while engaged with at least one cleaning element to remove build material from the build material distributor. In some examples, while positioned at the cleaning location and engaged with at least one cleaning element, the build material distributor may be rotated in a first rotational direction and the at least one cleaning element may be rotated in a second rotational direction that is opposite the first rotational direction to thereby remove build material from the build material distributor. In some examples, while positioned at the cleaning location and engaged with the at least one cleaning element, the at least one cleaning element may be rotated to thereby remove build material from the build material distributor.

[0027] A cleaning element, as used herein, may correspond to an at least partially deformable element. In such examples, when engaged with a build material distributor, a cleaning element may deform from a resting form. For example, the cleaning element may comprise a rubber-based wiping element, and engagement with the build material distributor may cause the rubber wiper to bend in a direction away from the build material distributor. As will be appreciated, the rubber wiping element may deform while maintaining contact with the build material distributor. As another example, a cleaning element may comprise a textile or fibrous material that may at deform and/or compress. Example types of cleaning elements may comprise a rotatable cleaning element, a deformable cleaning element, a wiping element (which may be referred to as a “wiper” or a “wiper blade”), a brush (e.g., a metal brush, a synthetic brush, etc.), a high-speed air blower, and/or other similar devices/components that may be used to remove particulate from a surface. In addition, example cleaning elements may comprise various types of materials, including for example, rubber/synthetic rubber based materials, textile based materials, fibrous based materials, metal based materials, and/or other types of materials that may be used in cleaning/removing devices.

[0028] Furthermore, in some examples described herein, a first build layer of build material and a second build layer of build material may be described. It will be appreciated that “first” and “second” are merely used for illustrative purposes. For consistency, some examples provided herein describe a topmost build layer of build material as a second build layer, and examples describe a build layer upon which a topmost layer of build material is distributed as a first build layer. Accordingly, it will be appreciated that in some examples first and second build layers may be sequential layers in a layer-wise additive manufacturing process. However, it will be noted that first and second do not necessarily describe an overall order of such build layers.

[0029] Turning now to the figures, and particularly to FIGS. 1 and 2, these figures provide block diagrams of some components example apparatuses 10, 50 for generating a three-dimensional object. In these examples, the apparatus 10, 50 may comprise a build material support 12, 52 having a surface that corresponds to a build area 14, 54. In the examples, the build material support 12, 52 is illustrated with dashed lines to reflect that a build material support may not be included in some examples. As will be appreciated, layers of build material may be distributed in the build area 14, 54 on the surface of the build material support 12, 52.

[0030] Furthermore, in the examples, the apparatus 10, 50 comprises a scanning carriage 16, 56 and a build material distributor 18, 58 coupled to the scanning carriage 16, 56. The scanning carriage 16, 56 may move bidirectionally along a scanning axis 20, 60 over the build area 14, 54. As will be appreciated, movement of the scanning carriage 16, 56 facilitates movement of the build material distributor 18, 58. The build material distributor 18, 58 may form build layers of build material in the build area 14, 54 during movement of the scanning carriage 16, 56 over the build area 14, 54.

[0031] Furthermore, the apparatus 10, 50 comprises a cleaning subsystem 22, 62 that is disposed at a cleaning location 24, 64. In this example, the cleaning subsystem 22, 62 comprises a cleaning element 26, 66 to remove build material from the build material distributor 18, 58. As shown, the cleaning location 24, 64 may be spaced apart from the build area 14, 54 such that build material removed with the cleaning element 26, 66 may not land in the build area 14, 54. In the examples, the scanning carriage 16, 56 and build material distributor 18, 58 may move along the scanning axis 20, 60 to the cleaning location 24, 54. When the build material distributor 18, 58 is positioned at the cleaning location 24, 64, the cleaning element 26, 66 may engage the build material distributor 18, 58.

[0032] As will be appreciated, as described herein, engagement of the cleaning element 26, 66 with the build material distributor 18, 58 may correspond to contact between at least one surface of the cleaning element 26, 66 and at least one surface of the build material distributor 18, 58. In some examples, the build material distributor 18, 58 and/or the cleaning element 26, 66 may move to remove build material from the build material distributor 18, 58.

[0033] Furthermore, referring particularly to FIG. 2, as shown, the scanning carriage 56 and build material distributor 58 may be moveable along the scanning axis 60 to a first position 68, a second position 70, and the cleaning location 64. In particular, during operation of the scanning carriage 56 and the build material distributor 56 to distribute a build layer of build material, the scanning carriage 56 and build material distributor 58 may move: along the scanning axis 60 from the first position 68 to the second position 70; or along the scanning axis 60 from the second position 70 to the first position 68.

[0034] During a cleaning operation of the apparatus 50, the scanning carriage 56 and the build material distributor 58 may move along the scanning axis 60 to the cleaning location 64. When the build material distributor 58 is positioned at the cleaning location 64, the cleaning element 66 may engage the build material distributor 58. In some examples, the build material distributor 58 and/or the cleaning element 66 may move to remove build material from the build material distributor 58.

[0035] FIG. 3 provides a block diagram that illustrates some components of an example apparatus 100 for generating a three-dimensional object. In this example, the apparatus 100 comprises a build material support 102 having a build surface 104 corresponding to a build area upon which build layers of build material may be distributed. In this example, the build material support 102 may move along a build axis 106. In particular, as build layers of build material are distributed on the build surface 104 of the build material support 102, the build material support may be moved along the build axis 106.

[0036] Furthermore, the example apparatus 100 comprises a scanning carriage 108 and a build material distributor 110 coupled to the scanning carriage 108. The scanning carriage 108 and build material distributor 110 may move bi-directionally along a scanning axis 112 over the build area. In this example, the build material distributor may rotate about an axis of rotation. In particular, the build material distributor 110 may rotate about the axis of rotation in a first rotational direction 114 (which is illustrated as a clockwise rotational direction) when the scanning carriage 108 and build material distributor 110 are moving in a first direction along the scanning axis 112, and the build material distributor may rotate about the axis of rotation in a second rotational direction 116 (which is illustrated as a counter clockwise rotational direction) when the scanning carriage 108 and build material distributor 110 are moving in a second direction along the scanning axis 112.

[0037] In addition, the apparatus 100 comprises a cleaning subsystem 120 that includes cleaning elements 122. In this example, the apparatus 100 comprises two cleaning elements; however, it will be appreciated that examples may include more or less cleaning elements (e.g., one cleaning element, three cleaning elements, etc.). The cleaning subsystem 120 further comprises a build material collection tray 124 disposed beneath the cleaning elements 122. The cleaning elements 122 may be coupled to an adjustable support member 126 such that the cleaning elements 122 may be movable along an adjustment axis 128. As discussed in other examples, the cleaning subsystem 120 may disposed at a cleaning location of the apparatus 100. In this example, when the build material distributor 110 is positioned at the cleaning location, the cleaning elements 122 may engage the build material distributor 110.

[0038] While positioned at the cleaning location and engaged with the cleaning elements 122, the build material distributor 110 may be rotated about the axis of rotation in the first rotational direction 114 or the second rotational direction 116. As will be appreciated, engagement of the build material distributor with the cleaning elements 122 during rotation of the build material distributor may remove build material temporarily adhered to a surface of the build material distributor 110. In this example, when build material is removed with the cleaning elements 122, the build material may be collected in the build material collection tray 124.

[0039] As shown in FIG. 3, the apparatus 100 may further comprise a build material supply subsystem 130. In this example, the build material supply subsystem 130 may have movable elements that have build material supply surfaces upon which build material may be conveyed from a build material supply to a location proximate the build area for distribution by the build material distributor 110. In some examples, the build material supply surfaces may be movable along axes parallel to the build axis 106. Furthermore, the apparatus 100 comprises excess build material collection trays 134. In this example, it will be noted that the cleaning substation 120 (and the cleaning location in which the cleaning station is disposed) is spaced apart from the build surface 104 such that a respective excess build material collection tray 134 is positioned between the cleaning subsystem 120 and the build surface 104.

[0040] To clean the build material distributor 110 of the apparatus 100, the build material distributor 110 may be positioned at the cleaning location such that the build material distributor 110 engages the cleaning elements 122. While engaged by the cleaning elements 122, the build material distributor 110 may be rotated in the first rotational direction 114 and/or the second rotational direction 116. In some examples, the build material distributor 110 may be rotated at a desired rotational speed. Due to engagement with the cleaning elements 122, build material temporarily adhered to the build material distributor may be removed during rotation of the build material distributor 110.

[0041] Furthermore, in this example, as previously discussed, the cleaning elements 122 may be movable along the adjustment axis 128. Accordingly, an engagement force between the build material distributor 110 and the cleaning elements 122 may be adjustable by movement of the cleaning elements 122 along the adjustment axis 128. In some examples, the build material distributor 110 may be moved to the cleaning location, and the cleaning elements 122 may be moved along the adjustment axis 128 to thereby engage the build material distributor 110. In some examples, the cleaning elements 122 may be moved along the adjustment axis 128 to engage the build material distributor 110 according to a desired engagement force.

[0042] As will be appreciated, an engagement force between the build material distributor 110 and the cleaning elements 122 (and therefore a relative position of the cleaning elements 122 on the adjustment axis) and a rotational speed of the build material distributor may be based at least in part at least one material property of the build material used in the apparatus 100 and/or at least one process parameter of the additive manufacturing process performed by the apparatus 100. Examples of the at least one material property of a build material may include critical temperature, melting point, etc. Examples of the at least one process parameter of the additive manufacturing process may comprise a build material distribution temperature, a build layer temperature profile (e.g., temperature values at various locations of a distributed build layer), a fusing temperature, system operating humidity, and/or other such environmental conditions that may be controlled in an additive manufacturing process.

[0043] While in the example of FIG. 3, the cleaning elements 122 may be adjustable along the adjustment axis 128, it will be appreciated that in other examples, cleaning elements may not be moveable/adjustable. In addition, in some examples, the cleaning elements may be removable. As a particular example, an apparatus may comprise a cleaning element in the form of a wiping element. The wiping element may be in a fixed position (i.e., not movable). In some examples, the cleaning element may be removable, such that the cleaning element may be replaceable. Therefore, in some examples, cleaning elements may be replaced based at least in part on material properties of the build material, process parameters, and/or material properties of the cleaning elements. For example, an apparatus may comprise a wiping element (such as a rubber wiper) that may be replaced after performing a predefined number of cleaning cycles.

[0044] In addition, it will be appreciated that the orientation and relative positioning of a cleaning element and the build material distributor (when positioned at the cleaning location) may vary from the examples provided herein. For example, a cleaning element may be adjustable along an adjustment axis having a different orientation relative to other components and axes of an apparatus. For example, a first cleaning element may have a first adjustment axis, and a second cleaning element may have a second adjustment axis, where a relative orientation of the first adjustment axis and the second adjustment axis may be parallel, perpendicular, or oblique. In addition, some examples may comprise cleaning elements disposed at different locations of the cleaning location. For example, an apparatus may comprise a first cleaning element in the form of a wiping element disposed such that the wiping element may engage a build material distributor at a first position. In this example, the apparatus may comprise a second cleaning element in the form of a rotatable cleaning element disposed such that the rotatable cleaning element may engage the build material distributor at a second position that is spaced apart from the first position. It will be appreciated that various other positions and configurations of cleaning elements may be implemented.

[0045] FIG. 4 provides a block diagram that illustrates some components of an example apparatus 150. As shown, the apparatus 150 comprises a build material distributor 152 that may be moved along a scanning axis 154 over a build area (not shown in FIG. 4) and to a cleaning location. Moreover, the build material distributor 152 may be rotatable. In this example, the build material distributor 152 is shown positioned at a cleaning location and engaged with a cleaning element 156. In this example, engagement of the cleaning element 156 and the build material distributor 152 may correspond to contact of a surface of the cleaning element 156 and a surface of the build material distributor 152. In this example, the cleaning element 156 may be rotatable. Accordingly, while the build material distributor 152 and the cleaning element 156 are engaged, the build material distributor 152 may rotate in a first rotational direction 158, and the cleaning element 156 may rotate in a second rotational direction 160. As shown in the example, the first rotational direction 158 and the second rotational direction 160 may be opposite (e.g., clockwise and counterclockwise).

[0046] Furthermore, in this example, the cleaning element 156 may be coupled to an adjustable support member 162 that may facilitate linear movement of the cleaning element along an adjustment axis 164. In this example the adjustable support member 162 is coupled to a build material collection tray 166 that is disposed under the cleaning element 156 to collect build material removed from the build material distributor 152.

[0047] While the example build material distributors of FIGS. 3 and 4 are illustrated as comprising a roller, it will be appreciated that other examples may implement other types of build material distributors. In some examples, a build material distributor may comprise a wiper blade and/or a spray mechanism. In such examples, it will be appreciated that example cleaning elements may correspond to the build material distributor, and the example cleaning elements may be implemented in a manner that corresponds to the build material distributor. For example, a rotatable cleaning element may be implemented to contact a surface of a wiper blade of a build material distributor.

[0048] FIG. 5 provides a block diagram that illustrates some components of an example apparatus 200. In this example, the apparatus 200 comprises a build material support 202 having a surface that corresponds to a build area 204 in which layers of build material may be deposited and fused in a layer-wise additive manufacturing process to form a three-dimensional object. In this example, the apparatus 200 comprises a scanning carriage 206 that may move bi-directionally along a scanning axis 208. In this example, the apparatus 200 includes a build material distributor 210 coupled to the scanning carriage 206. Accordingly, the build material distributor 210 may move over the build area 204 along the scanning axis 208 concurrent with movement of the scanning carriage 56. Furthermore, the apparatus 200 comprises an agent distributor 214 that may selectively distribute agent in the build area 204, and the apparatus 200 comprises at least one energy source 216 that may apply energy to build layers distributed in the build area 204.

[0049] As shown, a width of the build material distributor 210 may generally correspond to a width of the build area 54. Furthermore, the width of the build material distributor 210 may be approximately orthogonal to the scanning axis 208. Accordingly, as the scanning carriage 206 moves along the scanning axis 208 over the build area 204, the build material distributor 210 may distribute build material in a build layer.

[0050] In this example, the apparatus 200 further comprises a cleaning element 216 disposed at a cleaning location 217 of the apparatus 200. The scanning carriage 206 may be moved to the cleaning location 217 such that the build material distributor 210 is positioned at the cleaning location 217. Furthermore, when positioned at the cleaning location 217, the build material distributor 210 may be engaged with the cleaning element 216. When the build material distributor 210 is positioned at the cleaning location, build material may be removed from the build material distributor 210 with the cleaning element 216. In this example, it will be appreciated that a width of the cleaning element 216 may correspond to a width of the build material distributor 210.

[0051 ] Furthermore, the apparatus comprises a controller 218, where the controller 218 may be connected to the scanning carriage 206, build material distributor 210, agent distributor 214, energy source 216, and/or cleaning element 216. In such examples, the controller 218 may control connected components to thereby cause the performance of various operations described herein. A controller, such as the controller 218 of FIG. 5, may comprise a processing resource and/or a memory resource. A processing resource may comprise one or more general purpose data processors and/or one or more specialized data processors. For example, a processing resource may comprise a central processing unit (CPU), a graphics processing unit (GPU), an application-specific integrated circuit (ASIC), a controller, and/or other such configurations of logical components for data processing.

[0052] A memory resource may comprise random access memory (RAM) devices as well as other types of memory (e.g. cache memories, non-volatile memory devices, read-only memories, mass-storage resources, etc.). As will be appreciated, a memory resource may be a computer readable and/or machine-readable storage medium (e.g., RAM, ROM, erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory, flash memory or other solid state memory technology, portable compact disc memory, or other optical storage, or any other medium that may be used to store executable instructions and information).

[0053] Therefore, as described herein, a controller may be any combination of hardware and programming to implement the functionalities described with respect to a controller and/or a method. In some examples described herein, the combinations of hardware and programming may be implemented in a number of different ways. For example, the programming for the controller may be processor executable instructions stored on a non-transitory machine-readable storage medium and the hardware for the controller may include a processing resource to execute those instructions. In these examples, an apparatus implementing such controller may include the machine-readable storage medium storing the instructions and the processing resource to execute the instructions, or the machine-readable storage medium may be separately stored and accessible by the apparatus and the controller. In some examples, a controller may be implemented in circuitry.

[0054] In the example apparatus 200 of FIG. 5, the controller 218 may control: the scanning carriage 206 to move along the scanning axis 208; the build material distributor 210 to distribute build material in the build area 204; the agent distributor 214 to selectively distribute agent in the build area 204; the at least one energy source to apply energy to a build layer in the build area 204; and/or the build material distributor 210 and/or the cleaning element 216 to remove build material from the build material distributor 210.

[0055] FIG. 6 provides a block diagram that illustrates some components of an example apparatus 250 for generating a three-dimensional object. In this example, the apparatus 250 may comprise a build material support 252. In some examples, the build material support 252 may not be included in the apparatus 252; hence, the build material support 252 is illustrated in dashed line. As discussed previously, the build material support 252 may have a build surface that corresponds to a build area 254 in which layers of build material may be sequentially distributed and fused.

[0056] The example apparatus 250 comprises a first scanning carriage 256 and a second scanning carriage 258. In this example, the first scanning carriage 256 may move bi-directionally over the build area 254 along a first scanning axis 260, and the second scanning carriage 258 may move bidirectionally over the build area 254 along a second scanning axis 262. As will be appreciated, the first scanning axis 260 is approximately orthogonal to the second scanning axis 262. Furthermore, the first scanning axis 260 and the second scanning axis 262 are approximately parallel to a plane of the build surface of the build material support 252.

[0057] The apparatus 250 comprises energy sources 264 and a build material distributor 266 coupled to the first scanning carriage 256. Accordingly, as the first scanning carriage 256 moves along the first scanning axis 260, the apparatus 250 may distribute a layer of build material in the build area 254 with the build material distributor 266. Similarly, as the first scanning carriage 256 moves bi-directionally along the first scanning axis 260, the apparatus 250 may emit energy via the energy sources 264 to apply energy to a build layer in the build area 254.

[0058] The apparatus 250 comprises an agent distributor 268 coupled to the second scanning carriage 258. Accordingly, as the second scanning carriage 258 moves along the second scanning axis 262, the apparatus 250 may selectively distribute agent on a build layer in the build area 254 with the agent distributor 268. As will be appreciated, the example arrangement of the agent distributor 268, energy sources 264, and/or build material distributor 266 may be different in other examples. In another example, a build material distributor and an agent distributor may be coupled to a common scanning carriage. Other examples may comprise other arrangements. Similarly other example apparatuses may include more or less energy sources, more agent distributors, and/or more build material distributors.

[0059] In addition, the apparatus 250 comprises a cleaning subsystem 270 that includes cleaning elements 272. In this example, the apparatus comprises two cleaning elements; however, it will be appreciated that other examples may comprise more or less cleaning elements. The cleaning subsystem 270 is disposed at a cleaning location 274. The scanning carriage 256 and build material distributor 266 are moveable to the cleaning location 274. When the build material distributor 266 is positioned at the cleaning location 274, the build material distributor 266 may engage with the cleaning elements 272. As discussed previously, movement of the build material distributor 266 and/or cleaning elements 272 while engaged therewith may cause removal of build material from the build material distributor 266. As illustrated in other examples, the cleaning elements 272 of the apparatus 250 may comprise at least one wiper (such as the wiper elements 122 of FIG. 3), at least one rotatable element (such as the rotatable cleaning element 156 of FIG. 4), at least one brush, at least one air blower, or any combination thereof.

[0060] As shown, the apparatus 250 further comprises a controller 280, where the controller is connected to the first scanning carriage 256, the second scanning carriage 258, the energy sources 264, the build material distributor 266, the agent distributor 268, and/or the cleaning subsystem 270. Therefore, the controller 280 may control operation of the first scanning carriage 256, the second scanning carriage 258, the energy sources 264, the build material distributor 266, the agent distributor 268, and/or the cleaning subsystem 270. [0061 ] As shown, the controller 280 comprises at least one processing resource 282 and a memory resource 284. As discussed previously, the processing resource 282 may comprise a data processor, CPU, ASIC, or other such arrangements of logical components for processing data. Furthermore, the memory resource 284 may comprise a machine-readable storage medium. The memory resource 284 comprises instructions 286, where the instructions 286 are executable by the processing resource 282. Execution of the instructions 286 may cause the processing resource 282 and/or apparatus 250 to perform the functionalities, processes, and/or sequences of operations described herein.

[0062] For example, execution of the instructions 286 by the processing resource 282 may control movement of the scanning carriages 256, 258. In some examples, execution of the instructions 286 may cause the controller 280 to control the build material distributor 266 to distribute a build layer of build material in the build area. In addition, execution of the instructions 286 may cause the controller 280 to determine whether to clean the build material distributor. As will be appreciated, in some examples, the determining whether to clean the build material distributor may be based at least in part on at least one material property of a build material used by the apparatus and/or at least one process parameter of the additive manufacturing process performed by the apparatus.

[0063] FIGS. 7-12 provide flowcharts that provide example sequences of operations that may be performed by an example apparatus and/or a controller thereof to perform example processes and methods as described herein. In some examples, some operations included in the flowcharts may be embodied in a memory (such as the memory resource 284 of FIG. 6) in the form of instructions that may be executable by a processing resource to cause an apparatus and/or controller to perform the operations corresponding to the instructions. Additionally, the examples provided in FIGS. 7-12 may be embodied in computing devices, machine-readable storage mediums, processes, and/or methods. In some examples, the example processes and/or methods disclosed in the flowcharts of FIGS. 7-12 may be performed by a controller implemented in an apparatus.

[0064] FIG. 7 is a flowchart 300 that illustrates an example sequence of operations that may be performed by an example apparatus for generating a three-dimensional object. In this example, the apparatus may distribute at least one build layer of build material in a build area of the apparatus with a build material distributor (block 302). After distribution of the at least one build layer, the apparatus may move the build material distributor along a scanning axis to position the build material distributor at a cleaning location of the apparatus (block 304). While the build material distributor is positioned at the cleaning location, build material may be removed from the build material distributor with at least one cleaning element disposed at the cleaning location (block 306).

[0065] As discussed previously, in some examples, removing build material from the build material distributor with the at least one cleaning element may comprise moving at least one of the build material distributor or the at least one cleaning element while the build material distributor and the at least one cleaning element are engaged. In some examples removing build material from the build material distributor with the at least one cleaning element may comprise rotating the build material distributor while the build material distributor is engaged with the at least one cleaning element. In some examples, removing build material from the build material distributor may comprise rotating the build material distributor and the at least one cleaning element while the build material distributor is engaged with the at least one cleaning element. In some examples, removing build material from the build material distributor with the at least one cleaning element may comprise wiping the build material distributor with the at least one cleaning element by moving the at least one cleaning element in at least one direction while the build material distributor is engaged with the at least one cleaning element.

[0066] FIG. 8 provides a flowchart 350 that illustrates a sequence of operations that may be performed by an example apparatus. In this example, a build material distributor of the apparatus may be moved to a cleaning location of the apparatus such that the build material distributor engages at least one cleaning element that is disposed at the cleaning location (block 352). After the build material distributor is engaged with the at least one cleaning element, the build material distributor may be rotated in a first rotational direction (block 354), and the at least one cleaning element may be rotated in a second rotational direction that is opposite the first rotational direction (block 356). For example. the build material distributor may be rotated in a counterclockwise rotational direction, and the at least one cleaning element may be rotated in a clockwise rotational direction.

[0067] FIG. 9 provides a flowchart 370 that illustrates a sequence of operations that may be performed by an example apparatus. In this example, a build layer of build material may be distributed in a build area of the apparatus with a build material distributor (block 372). Agent may be selectively distributed on the build layer in the build area with an agent distributor of the apparatus (block 374). Energy may be applied to the build layer in the build area with at least one energy source of the apparatus (block 376). The build material distributor may be moved to a cleaning location of the apparatus (block 378), and build material may be removed from the build material distributor with at least one cleaning element disposed at the cleaning location (block 380).

[0068] FIG. 10 provides a flowchart 400 that illustrates a sequence of operations that may be performed by an example apparatus and/or an example controller thereof. As shown, the controller may control a scanning carriage of the apparatus to move along a scanning axis over a build area of the apparatus (block 402). The controller may control a build material distributor coupled to the scanning carriage to distribute at least one build layer in the build area (block 404). After distribution of the at least one build layer, the controller may determine whether to clean the build material distributor (block 406).

[0069] In some examples, determining whether to clean the build material distributor may be based at least in part on at least one material property of the build material used by the apparatus. In some examples, determining whether to clean the build material distributor may be based at least in part on at least one process parameter of the additive manufacturing process performed by the apparatus. For example, a material property of the build material used in performing operations described herein may have a melting point of a particular temperature. Based at least in part on the melting point, the controller may determine that the build material distributor is to be cleaned after distribution of three respective build layers. In this example, after distribution of three respective build layers with the build material distributor, the controller may determine to clean the build material distributor. As another example, a process parameter of the additive manufacturing process performed by the apparatus may be a build material distribution temperature. Based at least in part on the build material distribution temperature, the controller may determine that the build material distributor is to be cleaned after distribution of each respective build layer. In this example, after distribution of each respective build layer, the controller may determine to clean the build material distributor.

[0070] As will be appreciated, in some examples the controller may determine whether to clean the build material distributor based at least in part on at least one material property of the build material and at least one process parameter. Furthermore, while the examples described herein discuss cleaning of the build material after distribution of a particular number of build layers, it will be appreciated that other examples may determine to clean the build material distributor after distribution of other numbers of build layers (e.g., two layers, four layers, five layers to ten layers, etc.).

[0071 ] In some examples, determining whether to clean a build material distributor may be dynamic such that the controller may not determine to clean the build material distributor after a determined number of distributed build layers. In such examples, the controller may determine whether to clean the build material distributor based at least in part on at least one material property and/or at least one process parameter after distribution of each respective layer of build material. For example, the controller may determine whether to clean the build material distributor based at least in part on a build layer temperature of the topmost build layer of build material distributed in the build area. In this example, a build layer temperature comprises temperatures for locations of the build area (where the build layer temperature may be referred to as a build layer temperature profile).

[0072] In response to a determination to not clean the build material distributor (“N” branch of block 406), the controller may continue controlling the scanning carriage and controlling the build material distributor as described in blocks 402-404. In response to a determination to clean the build material distributor (“Y” branch of block 406), the controller may control the scanning carriage to move to a cleaning location of the apparatus such that the build material distributor is engaged with at least one cleaning element (block 408). When the build material distributor is positioned at the cleaning location and engaged with the at least one cleaning element, the controller may control the build material distributor to rotate (block 410). Accordingly, concurrent engagement with the at least one cleaning element and rotation of the build material distributor may cause build material temporarily adhered to the build material distributor to be removed. In some examples, concurrent with rotation of the build material distributor, the controller may control the at least one cleaning element to rotate (block 412). In such examples, concurrent rotation of the build material distributor and the at least one cleaning element may facilitate removal of build material from the build material distributor.

[0073] After removal of build material from the build material distributor by rotation of the build material distributor (block 410) or by rotation of the build material distributor and the at least one cleaning element (block 412), the controller may continue controlling the scanning carriage and the build material distributor as described with regard to blocks 402-404.

[0074] FIG. 11 provides a flowchart 450 that illustrates a sequence of operations that may be performed by an example apparatus or an example controller thereof. In this example, the controller may determine to clean a build material distributor of the apparatus based at least in part on at least one material property of build material used and/or at least one process parameter (block 452). In response to determining to clean the build material distributor, the controller may control a scanning carriage to move the build material distributor to a cleaning location of the apparatus (block 454). After the build material distributor is positioned at the cleaning location, the controller may control at least one cleaning element to engage the build material distributor (block 456). As discussed, in some examples, a cleaning element may be movable along an adjustment axis. Therefore, in some examples, the controller may control movement of the at least one cleaning element along the adjustment axis to thereby cause the at least one cleaning element to engage the build material distributor. After the at least one cleaning element engages the build material distributor, the controller may control the build material distributor to rotate (block 458).

[0075] FIG. 12 is a flowchart 500 that illustrates an example sequence of operations that may be performed by an example apparatus and/or an example controller thereof. The controller may control a scanning carriage to move along a scanning axis over a build area of the apparatus between a first position and a second position (block 502). The controller may control a build material distributor coupled to the scanning carriage to distribute at least one build layer of build material in the build area concurrent with movement of the scanning carriage over the build area (block 504). The controller may control an agent distributor of the apparatus to selectively distribute agent in the build area on each build layer (block 506). The controller may control at least one energy source to apply energy to each build layer (block 508). The controller may control the scanning carriage to move to a cleaning location of the apparatus to thereby engage the build material distributor with at least one cleaning element disposed at the cleaning location (block 510). The controller may control the build material distributor to rotate when positioned at the cleaning location and engaged with the at least one cleaning element (block 512).

[0076] Therefore, example apparatuses and processes described herein facilitate removal of build material from a build material distributor. In particular, examples facilitate removal of residual build material temporarily adhered to the build material distributor after distribution of a build layer of build material. Removal of such residual build material may improve build material distribution in subsequent build layers. For example, removal of residual build material may facilitate improved build layer uniformity in subsequently distributed build layers. In turn, examples described herein may facilitate improved dimensional accuracy in generating three-dimensional objects.

[0077] While various examples are described herein, elements and/or combinations of elements may be combined and/or removed for various examples contemplated hereby. For example, the example operations provided herein in the flowcharts of FIGS. 7-12 may be performed sequentially, concurrently, or in a different order. Moreover, some example operations of the flowcharts may be added to other flowcharts, and/or some example operations may be removed from flowcharts. Furthermore, in some examples, various components of the example apparatuses of FIGS. 1-6 may be removed, and/or other components may be added. Similarly, in some examples various instructions of stored in memory resources and/or machine-readable storage mediums (such as the memory resource of FIG. 6) may correspond to the example operations of FIGS. 7-12.

[0078] The preceding description has been presented to illustrate and describe examples of the principles described. This description is not intended to be exhaustive or to limit these principles to any precise form disclosed. Many modifications and variations are possible in light of the above disclosure.

Claims

CLAIMS:

1. An apparatus for generating a three-dimensional object, the apparatus comprising: a scanning carriage to move along a scanning axis over a build area, the scanning carriage to move along the scanning axis to a cleaning location; a build material distributor coupled to the scanning carriage, the build material distributor to distribute build material in the build area during movement of the scanning carriage over the build area, and the build material distributor to move to the cleaning location when the scanning carriage moves to the cleaning position; and a cleaning subsystem comprising at least one cleaning element, the cleaning subsystem disposed in the cleaning location, the cleaning element to engage the build material distributor and to remove build material from the build material distributor when the build material distributor is positioned at the cleaning location.

2. The apparatus of claim 1, wherein the build material distributor is rotatable, and the build material distributor is to rotate when the at least one cleaning element is engaged with the build material distributor to remove build material from the build material distributor.

3. The apparatus of claim 1, wherein the build material distributor is rotatable, and the at least one cleaning element is a rotatable cleaning element, and wherein the build material distributor is to rotate in a first rotational direction and the rotatable cleaning element is to concurrently rotate in a second rotational direction that is opposite the first rotational direction when the rotatable cleaning element is engaged with the build material distributor to remove build material from the build material distributor.

4. The apparatus of claim 1, wherein the at least one cleaning element is moveable along an adjustment axis, the at least one cleaning element to move along the adjustment axis to engage the build material distributor when the build material distributor is positioned at the cleaning location.

5. The apparatus of claim 1, wherein the at least one cleaning element comprises a wiping element, a rotatable cleaning element, a brush, an air blower, or any combination thereof.

6. The apparatus of claim 1, wherein the build material distributor is rotatable, the apparatus further comprising: a controller to: determine whether to clean the build material distributor; and in response to determining to clean the build material distributor, control the scanning carriage to move the scanning carriage to the cleaning location such that the build material distributor is positioned at the cleaning location and engaged with the at least one cleaning element; and after the build material distributor is positioned at the cleaning location, control the build material distributor to rotate.

7. The apparatus of claim 6, wherein the controller controls the build material distributor to rotate in a first rotational direction, the at least one cleaning element is a rotatable cleaning element, and the controller is further to: control the rotatable cleaning element to rotate in a second rotational direction that is opposite the first rotational direction.

8. The apparatus of claim 1, further comprising: a controller to: control the build material distributor to distribute at least one build layer of build material in the build area; after distribution of the at least one build layer of build material in the build area, determine whether to clean the build material distributor based at least in part on at least one material property of the build material; in response to a determination to clean the build material distributor, control the scanning carriage to move the scanning carriage to the cleaning location such that the at least one cleaning element is engaged with the build material distributor; and control the build material distributor to rotate while engaged with the at least one cleaning element to thereby cause removal of build material from the build material distributor.

9. The apparatus of claim 1, further comprising: an agent distributor to selectively distribute agent in the build layer; and at least one energy source, wherein the cleaning subsystem comprises a build material collection tray disposed beneath the at least one cleaning element.

10. A method for an apparatus for generating a three-dimensional object, the method comprising: distributing at least one build layer of build material in a build area with a build material distributor of the apparatus; moving the build material distributor along a scanning axis to thereby position the build material distributor at a cleaning location; when the build material distributor is positioned at the cleaning location, removing build material from the build material distributor with at least one cleaning element disposed at the cleaning location.

11. The method of claim 10, wherein the at least one cleaning element engages the build material distributor when the build material distributor is positioned at the cleaning location, and removing build material from the build material distributor with the at least one cleaning element of the cleaning subsystem positioned at the cleaning subsystem comprises: rotating the build material distributor such that engagement of the cleaning element and rotation of the build material distributor removes build material from the build material distributor.

12. The method of claim 11, wherein the build material distributor is rotated in a first rotational direction, and removing build material from the build material distributor with the at least one cleaning element of the cleaning subsystem positioned at the cleaning subsystem comprises: concurrent with rotating the build material distributor in the first rotational direction, rotating the at least one cleaning element in a second rotational direction that is opposite the first rotational direction.

13. An apparatus for generating a three-dimensional object, the apparatus comprising: an agent distributor to selectively distribute agent in a build area; at least one energy source; a scanning carriage to move along a scanning axis over the build area, the scanning carriage to move to a first position, a second position on an opposite side of the build area from the first position, and a cleaning location that is spaced apart from the build area; a build material distributor coupled to the scanning carriage such that the build material distributor moves along the scanning axis over the build area concurrent with movement of the scanning carriage, the build material distributor to distribute build material in the build area; and at least one cleaning element disposed at a cleaning location of the apparatus, the at least one cleaning element to engage with the build material distributor when the build material distributor is positioned at the cleaning location, the at least one cleaning element to remove build material from the build material distributor.

14. The apparatus of claim 13, further comprising: a controller to: control the scanning carriage to move along the scanning axis over the build area between the first position and the second position; control the build material distributor to distribute build layers of build material in the build area concurrent with movement of the scanning carriage over the build area; control the agent distributor to selectively distribute agent in the build area on build layers distributed in the build area; control the at least one energy source to apply energy to build layers distributed in the build area; control the scanning carriage to move to the cleaning location to thereby engage the build material distributor and the at least one cleaning element; and control the build material distributor to rotate when positioned at the cleaning location and engaged with the at least one cleaning element to thereby remove build material from the build material distributor.

15. The apparatus of claim 14, wherein the controller is further to: determine whether to clean the build material distributor based at least in part on at least one material property of the build material or at least one process parameter, wherein the controller controls the scanning carriage to move to the cleaning location and controls the build material distributor to rotate in response to a determination to clean the build material distributor.