EP3946899A1

EP3946899A1 - Additive manufacturing

Info

Publication number: EP3946899A1
Application number: EP20716799.0A
Authority: EP
Inventors: Joseph Gwilliam CRABTREE; Konstantin RYBALCENKO; Viktor PAP-KOVÁCS
Original assignee: Additive Manufacturing Technologies Ltd
Current assignee: Additive Manufacturing Technologies Ltd
Priority date: 2019-04-05
Filing date: 2020-04-06
Publication date: 2022-02-09
Also published as: WO2020201581A1; GB202102615D0; GB2596175B; GB201904816D0; GB2596175A

Abstract

An apparatus (100) for additively manufacturing a part. The apparatus comprises a build bed (104) for supporting a powder material, a powder surface preparation device (106) for preparing a surface of the powder material and an energy emitting device (108) for energising the powder surface based on a desired part geometry. The build bed is controllably moveable along a closed loop transport path which extends around a horizontal axis. Advantageously, it has been found that the provision of a transport path which extends around a horizontal axis provides for more easy access to the parts located on said path. Subsequently, operational efficiency can be improved.

Description

ADDITIVE MANUFACTURING

The present invention relates to additive manufacturing (AM) and in particular, but not exclusively, to an improved method of manufacturing parts using a powder-based AM process.

Additive Manufacturing is a process where objects are manufactured from a polymer, metal, ceramic or other material in a layer-by-layer fashion by binding together the material. Powder bed sintering is an AM method where a polymer, metal, ceramic or other powder material is bound together using an energy source, e.g. an infra-red lamp or laser, which moves linearly back and forth across a print bed. High Speed Sintering (HSS) and Multi Jet Fusion (MJF) 3D printers are known powder bed sintering apparatus, where the powder is sintered/fused with detailing agent and thermal energy. These particular systems are also sometimes called inkjet or jet-on-powder methods.

Another powder-based AM method is Selective Laser Sintering (SLS) which uses a fixed laser or a number of lasers as the energy source to sinter powdered material, typically nylon/polyamide, by aiming the laser automatically at points in space defined by a 3D model to bind the material together and create a solid structure. The laser selectively fuses powdered material by scanning cross-sections generated from a 3D digital description of the part (for example from a CAD file or scan data) on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by one-layer thickness, a new layer of material is applied on top, and the process is repeated until the part is completed.

The process typically takes place in an inert gas environment to prevent the material, e.g. nylon, oxidising when heated by the laser beam. The temperature inside the build chamber is typically kept relatively high but below the melting point of the un-sintered powder, e.g. around 170°C for nylon, so that the temperature increase required by the laser to fuse the surface particles is relatively low.

Current powder bed sintering methods involve back and forth movement of the powder deposition and, in the case of inkjet type of methods, back and forth movement of a thermal energy source and a curing unit. This involves accelerating the units to one side of the powder bed, suddenly stopping them, and accelerating the units to the opposite side of the powder bed where they are again suddenly stopped. This process is repeated until the AM part is formed. Mechanically, this creates significant stress on the drive assembly, e.g. transport mechanism, gears, motors and the like, especially when the printing speed is increased. Furthermore, the back and forth movement of the energy source over the print bed undesirably leads to noise, vibration and harshness (NVH) problems, maintenance issues, and costly downtime of the printing apparatus.

It is an aim of certain embodiments of the present invention to improve the efficiency and speed of powder-based additive manufacturing.

It is an aim of certain embodiments of the present invention to provide a method and apparatus for moving at least one print bed with respect to at least one powder deposition unit and at least one energy emission unit, or vice versa, along a closed loop transport path to thereby minimise the mechanical stress on the drive assembly and reduce NVH problems, maintenance issues, and costly downtime of the printing apparatus.

According to a first aspect of the present invention there is provided an apparatus for additively manufacturing a part, the apparatus comprising:

a plurality of build beds, each build bed having a powder supporting platform for supporting a powder material;

at least one powder surface preparation device for preparing a surface of the powder material supported on at least one of said build beds; and

at least one energy emitting device for energising a powder surface prepared on at least one of said build beds based on a desired part geometry,

wherein the plurality of build beds are controllably moveable along a closed loop transport path.

In exemplary embodiments, the closed loop transport path extends around a horizontal axis. Advantageously, it has been found that the provision of a transport path which extends around a horizontal axis provides for more easy access to the parts located on said path, even when the apparatus is in use, which helps processes to be run continuously and subsequently operational efficiency can be improved.

Conversely, in the prior art, the transport path is much more difficult to access and hence requires periodic stopping to remove and replace parts, thereby reducing operational efficiency. In exemplary embodiments, the plurality of build beds are supported on a transporter which defines the closed loop transport path.

In exemplary embodiments, the plurality of build beds are separable from the transporter.

In exemplary embodiments, the plurality of build beds are separable from to the apparatus.

In exemplary embodiments, the plurality of build beds are moveable with respect to the transporter.

In exemplary embodiments, the plurality of build beds are releasably coupled to the transporter. In exemplary embodiments, the transporter is a conveyor.

In exemplary embodiments, the transporter is a conveyor belt or a conveyor belt assembly. In exemplary embodiments, the transporter is a chain conveyor.

In exemplary embodiments, the plurality of build beds are releasably coupled to and moveable with respect to the transporter. In exemplary embodiments, the plurality of build beds are a plurality of spaced apart build beds.

In exemplary embodiments, movement of the plurality of build beds along the closed loop transport path is controlled by a controller.

In exemplary embodiments, movement of the plurality of build beds along the closed loop transport path is controlled by a controller based on the desired part geometry and/or the powder material and/or the energy emitting device. In exemplary embodiments, the powder supporting platform of each of the plurality of build beds is controllably moveable between a first position and a second position for adjusting a height of each powder supporting platform respectively.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above the closed loop transport path.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above at least one of said build beds when preparing or energising the surface of the powder material supported by at least one of said build beds.

In exemplary embodiments, the powder supporting platform of each of the plurality of build beds is controllably moveable between a first position and a second position for adjusting a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above at least one of said build beds at a predetermined height relative to at least one of said build beds when preparing or energising the surface of the powder material.

In exemplary embodiments, the powder supporting platform of each of the plurality of build beds is controllably moveable between a first position and a second position for adjusting the relative height of the at least one powder surface preparation device and/or the energy emitting device relative to the powder material.

In exemplary embodiments, the powder supporting platform of each of the plurality of build beds are controllably moveable along a vertical axis.

In exemplary embodiments, the at least one powder surface preparation device and/or the energy emitting device is controllably moveable between a first position and a second position for adjusting a height of the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above the closed loop transport path when preparing or energising the surface of the powder material.

In exemplary embodiments the at least one powder surface preparation device and/or the energy emitting device is controllably moveable between a first position and a second position for adjusting a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above the closed loop transport path at a predetermined height relative to the powder material when preparing or energising the surface of the powder material supported by at least one of said build beds.

In exemplary embodiments the at least one powder surface preparation device and/or the energy emitting device is controllably moveable between a first position and a second position for adjusting the relative height between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the at least one powder surface preparation device and/or the energy emitting device is controllably moveable along a vertical axis.

In exemplary embodiments, the apparatus further comprises at least one curing device located on the closed loop transport path.

In exemplary embodiments, the apparatus further comprises at least one curing device located on the closed loop transport path upstream of the at least one energy emitting device for curing the powder material before the powder material has been energised.

In exemplary embodiments, the apparatus further comprises at least one curing device located on the closed loop transport path downstream of the at least one energy emitting device for curing the powder material after the powder material has been energised.

In exemplary embodiments, the at least one powder surface preparation device and the energy emitting device are controllably moveable along the closed loop transport path.

In exemplary embodiments, the plurality of build beds and the at least one powder surface preparation device and the energy emitting device are controllably moveable along the closed loop transport path. In exemplary embodiments, the plurality of build beds and the at least one powder surface preparation device are controllably moveable along the closed loop transport path. In exemplary embodiments, the plurality of build beds and the at least one energy emitting device are controllably moveable along the closed loop transport path.

In exemplary embodiments, the at least one energy emitting device comprises a laser or a heat lamp.

In exemplary embodiments, the at least one powder surface preparation device comprises a roller or scraper.

According to a second aspect of the present invention there is provided an additive manufacturing system comprising apparatus according to the first aspect of the present invention.

According to a third aspect of the present invention there is provided a method of additively manufacturing a part, comprising:

providing a plurality of build beds each build bed having a powder supporting platform, the powder supporting platform of at least one of said build beds supporting a powder material;

preparing a surface of the powder material supported on at least one of said build beds by at least one powder surface preparation device;

controllably moving the plurality of build beds along a closed loop transport path, the closed loop transport path extending around a horizontal axis, and

energising the powder surface prepared by the at least one powder surface preparation device based on a desired part geometry. In exemplary embodiments, the method comprises:

providing a plurality of build beds each build bed having a powder supporting platform supporting a powder material;

preparing a surface of the powder material supported on the plurality of build beds by at least one powder surface preparation device; controllably moving the plurality of build beds along a closed loop transport path, the closed loop transport path extending around a horizontal axis, and

energising the powder surface prepared by the at least one powder surface preparation device based on a desired part geometry.

In exemplary embodiments, the plurality of build beds are supported on a transporter defining the closed loop transport path.

In exemplary embodiments, the method further comprises removing at least one of the plurality of build beds from the transporter after the powder surface has been energised by the at least one energy emitting device.

In exemplary embodiments, the method further comprises replacing the at least one build bed on the transporter after the at least one build bed has been removed from the transporter.

In exemplary embodiments, the method further comprises placing an additional build bed onto the transporter.

In exemplary embodiments, the method further comprises moving the plurality of build beds along the closed loop transport path based on the desired part geometry.

In exemplary embodiments, the method further comprises moving the plurality of build beds along the closed loop transport path based on the powder material.

In exemplary embodiments, the method further comprises moving the plurality of build beds along the closed loop transport path based on the energy emitting device.

In exemplary embodiments, the method further comprises moving the plurality of build beds along the closed loop transport path based on the desired part geometry and/or the powder material and/or the energy emitting device. In exemplary embodiments, the method further comprises moving the powder supporting platform of the at least one of build bed between a first position and a second position so as to adjust a height of the powder supporting platform. In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path.

In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path whilst preparing or energising the surface of the powder material.

In exemplary embodiments, the method further comprises moving the powder supporting platform of the at least one of build bed between a first position and a second position so as to adjust a clearance between the powder material nd the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path at a predetermined height relative to the powder material whilst preparing or energising the surface of the powder material.

In exemplary embodiments, the method further comprises moving the powder supporting platform of the at least one of build bed between a first position and a second position so as to adjust the relative height between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the method further comprises moving at least one of the respective powder supporting platforms along a vertical axis.

In exemplary embodiments, the method further comprises moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to adjust a height of the at least one powder surface preparation device and/or the energy emitting device. In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path.

In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path whilst preparing or energising the surface of the powder material. In exemplary embodiments, the method further comprises moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to adjust a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the method further comprises moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to a adjust the relative height between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the method further comprises moving the at least one powder surface preparation device and/or the energy emitting device along a vertical axis.

In exemplary embodiments, the clearance between the powder material supported on the powder supporting platform of at least one of said build beds and the at least one powder surface preparation device and/or the energy emitting device is adjusted based on a thickness of a new powder layer providing the powder surface. In exemplary embodiments, the method further comprises curing the powder material by at least one curing device located on the closed loop transport path upstream and/or downstream of the at least one energy emitting device.

In exemplary embodiments, the method further comprises curing the powder material by at least one curing device located on the closed loop transport path upstream of the at least one energy emitting device.

In exemplary embodiments, the method further comprises curing the powder material by at least one curing device located on the closed loop transport path downstream of the at least one energy emitting device.

In exemplary embodiments, the method further comprises moving the plurality of build beds around the transport path a plurality of times until the desired part has been formed.

In exemplary embodiments, the at least one build bed and the at least one powder surface preparation device and the at least one energy emitting device are controllably moved along the closed loop transport path.

In exemplary embodiments, the method comprises:

moving the at least one powder surface preparation device and/or the at least energy emitting device around the closed loop transport path a plurality of times until the desired part has been formed.

In exemplary embodiments, energising comprises laser sintering/fusing.

In exemplary embodiments, the powder surface comprises Nylon™.

According to a fourth aspect of the present invention there is provided apparatus for additively manufacturing a part, comprising:

at least one build bed for supporting a powder material; at least one powder surface preparation device for preparing a surface of the powder material; and

at least one energy emitting device for energising the powder surface based on a desired part geometry,

wherein the at least one build bed and/or the at least one powder surface preparation device and the energy emitting device are controllably moveable around a closed loop transport path.

In exemplary embodiments, movement of the at least one build bed and/or the at least one powder surface preparation device and the energy emitting device along the transport path is controlled by a controller based on the desired part geometry and/or the powder material and/or the energy emitting device.

In exemplary embodiments, the at least one build bed comprises a powder supporting platform controllably moveable by a predetermined distance away from the at least one energy emitting device.

In exemplary embodiments, the at least one powder surface preparation device and/or the energy emitting device is controllably moveable by a predetermined distance away from the powder material.

In exemplary embodiments, the at least one build bed is supported on a transport element defining the closed loop transport path.

In exemplary embodiments, the at least one build bed is coupled to and moveable with respect to or with the transport element.

In exemplary embodiments, the at least one build bed comprises a plurality of spaced apart build beds.

In exemplary embodiments, the at least one build bed comprises a substantially circular/annular build bed around which the at least one energy emitting device is controllably rotatable about a rotation axis. In exemplary embodiments, the at least one energy emitting device extends radially outwardly from a drive shaft defining the rotation axis.

In exemplary embodiments, the at least one energy emitting device is controllably moveable in a direction parallel to the rotation axis.

In exemplary embodiments, the at least one powder surface preparation device is controllably rotatable about the rotation axis in advance of the at least one energy emitting device.

In exemplary embodiments, the apparatus further comprises at least one curing device located on the transport path and upstream and/or downstream of the at least one energy emitting device.

In exemplary embodiments, the energy emitting device comprises a laser or a heat lamp.

According to a fifth aspect of the present invention there is provided an additive manufacturing system comprising apparatus according to the first aspect of the present invention.

According to a sixth aspect of the present invention there is provided a method of additively manufacturing a part, comprising:

providing a powder surface on at least one build bed by at least one powder surface preparation device; and

energising the powder surface by at least one energy emitting device based on a desired part geometry,

wherein the at least one build bed and/or the at least one powder surface preparation device and the at least one energy emitting device are controllably moved around a closed loop transport path.

In exemplary embodiments, the method comprises:

moving the at least one build bed and/or the at least one powder surface preparation device and the at least one energy emitting device along the transport path based on the desired part geometry and/or the powder material and/or the energy emitting device.

In exemplary embodiments, the method comprises:

moving a powder supporting platform of the at least one build bed away from the at least one powder surface preparation device and the at least one energy emitting device by a predetermined distance.

In exemplary embodiments, the method comprises:

moving the at least one powder surface preparation device and/or the at least one energy emitting device by a predetermined distance away from the powder material.

In exemplary embodiments, the predetermined distance corresponds to a thickness of a new powder layer providing the powder surface.

In exemplary embodiments, the method comprises:

rotating the at least one powder surface preparation device and the at least one energy emitting device about a rotation axis and around a substantially circular/annular build bed.

In exemplary embodiments, the method comprises:

moving the at least one energy emitting device in a direction parallel to the rotation axis.

In exemplary embodiments, the method comprises:

curing the powder material by at least one curing device located on the transport path and upstream and/or downstream of the at least one energy emitting device.

In exemplary embodiments, the method comprises:

moving the at least one build bed and/or the at least one powder surface preparation device and the at least energy emitting device around the transport path a plurality of times until the desired part has been formed. In exemplary embodiments, energising comprises laser sintering/fusing.

In exemplary embodiments, the powder surface comprises Nylon™.

According to a seventh aspect of the present invention there is provided an apparatus for additively manufacturing a part, comprising:

at least one energy emitting device for energising the powder surface prepared on at least one of said build beds based on a desired part geometry,

wherein the plurality of build beds are controllably moveable along a closed loop transport path, and

wherein the at least one powder surface preparation device and the energy emitting device are controllably moveable along the closed loop transport path for accessing at least one of the plurality of build beds. In exemplary embodiments, the plurality of build beds are supported on a transporter which defines the closed loop transport path.

In exemplary embodiments, the plurality of build beds are releasably coupled to the transporter. In exemplary embodiments, the plurality of build beds are releasably coupled to and moveable with respect to the transporter.

In exemplary embodiments, the plurality of build beds are a plurality of spaced apart build beds.

In exemplary embodiments, movement of the plurality of build beds along the closed loop transport path is controlled by a controller. In exemplary embodiments, movement of the plurality of build beds along the closed loop transport path is controlled by a controller based on the desired part geometry and/or the powder material and/or the energy emitting device.

In exemplary embodiments, the powder supporting platform of each of the plurality of build beds is controllably moveable between a first position and a second position for adjusting a height of each powder supporting platform respectively.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above at least one of said build beds when preparing or energising the surface of the powder material.

In exemplary embodiments, the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above the closed loop transport path at a predetermined height relative to the powder material when preparing or energising the surface of the powder material. In exemplary embodiments the at least one powder surface preparation device and/or the energy emitting device is controllably moveable between a first position and a second position for adjusting the relative height between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the at least one powder surface preparation device and/or the energy emitting device is controllably moveable along a vertical axis. In exemplary embodiments, the apparatus further comprises at least one curing device located on the closed loop transport path.

In exemplary embodiments, the plurality of build beds and the at least one powder surface preparation device and the energy emitting device are controllably moveable along the closed loop transport path. In exemplary embodiments, the plurality of build beds and the at least one powder surface preparation device are controllably moveable along the closed loop transport path.

In exemplary embodiments, the plurality of build beds and the at least one energy emitting device are controllably moveable along the closed loop transport path.

In exemplary embodiments, the at least one powder surface preparation device comprises a roller or scraper. In exemplary embodiments, the plurality of build beds are substantially circular/annular build beds around which the at least one energy emitting device is controllably rotatable about a rotation axis.

In exemplary embodiments, the at least one energy emitting device extends radially outwardly from a drive shaft defining the rotation axis.

In exemplary embodiments, the at least one energy emitting device is controllably moveable in a direction parallel to the rotation axis. In exemplary embodiments, the at least one powder surface preparation device is controllably rotatable about the rotation axis in advance of the at least one energy emitting device.

According to an eighth aspect of the present invention there is provided a method of additively manufacturing a part, comprising:

providing a plurality of build beds each build bed having a powder supporting platform, the powder supporting platform of at least one of said build beds supporting a powder material; controllably moving the plurality of build beds along a closed loop transport path;

controllably moving at least one powder surface preparation device along the closed loop transport path so as to access the powder material supported by at least one of said build beds;

preparing a surface of the powder material supported by at least one of said build beds by the at least one powder surface preparation device;

controllably moving at least one energy emitting device along the closed loop transport path so as to access the powder material prepared by the at least one powder surface preparation device; and

energising the powder surface prepared by the at least one powder surface preparation device based on a desired part geometry..

In exemplary embodiments, the method comprises:

controllably moving the plurality of build beds along a closed loop transport path; controllably moving at least one powder surface preparation device along the closed loop transport path so as to access the powder material supported by the plurality of build beds;

preparing a surface of the powder material supported by the plurality of build beds by the at least one powder surface preparation device;

In exemplary embodiments, the method further comprises removing at least one of the plurality of build beds from the transporter after the powder surface has been energised by the at least one energy emitting device. In exemplary embodiments, the method further comprises replacing the at least one build bed on the transporter after the at least one build bed has been removed from the transporter.

In exemplary embodiments, the method further comprises moving the plurality of build beds along the closed loop transport path based on the desired part geometry and/or the powder material and/or the energy emitting device.

In exemplary embodiments, the method further comprises moving the powder supporting platform of the at least one of build bed between a first position and a second position so as to adjust a height of the powder supporting platform.

In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path.

In exemplary embodiments, the method further comprises moving the powder supporting platform of the at least one of build bed between a first position and a second position so as to adjust a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the method further comprises moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to adjust a height of the at least one powder surface preparation device and/or the energy emitting device.

In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path whilst preparing or energising the surface of the powder material. In exemplary embodiments, the method further comprises moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to adjust a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device. In exemplary embodiments, the method further comprises locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path at a predetermined height relative to the powder material whilst preparing or energising the surface of the powder material.

In exemplary embodiments, the clearance between the powder material supported on the powder supporting platform of at least one of said build beds and the at least one powder surface preparation device and/or the energy emitting device is adjusted based on a thickness of a new powder layer providing the powder surface.

In exemplary embodiments, the method further comprises curing the powder material by at least one curing device located on the closed loop transport path upstream and/or downstream of the at least one energy emitting device.

In exemplary embodiments, the method further comprises curing the powder material by at least one curing device located on the closed loop transport path downstream of the at least one energy emitting device. In exemplary embodiments, the method further comprises moving the plurality of build beds around the transport path a plurality of times until the desired part has been formed.

In exemplary embodiments, the method comprises:

In exemplary embodiments, energising comprises laser sintering/fusing.

In exemplary embodiments, the powder surface comprises Nylon™.

In exemplary embodiments, the method comprises:

Description of the Drawings

Certain embodiments of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 illustrates a schematic plan view of an apparatus according to certain embodiments of the present invention for continuous additive manufacturing;

Figure 2 illustrates a schematic representation of one of the build beds of the apparatus of Figure 1 ; Figure 3 illustrates the operational interaction between the sintering unit and each build bed of the apparatus of Figure 1 ;

Figure 4 illustrates a schematic plan view of a further apparatus according to certain embodiments of the present invention for continuous additive manufacturing;

Figure 5a illustrates a schematic side view of a further apparatus according to certain embodiments of the present invention for continuous additive manufacturing; Figure 5b illustrates a schematic plan view of the apparatus of Figure 5a;

Figure 5c illustrates a schematic plan view section of the apparatus of Figures 5a and 5b; and Figure 6 illustrates a process flow chart for printing parts in a continuous manner according to certain embodiments of the present invention.

Detailed Description As illustrated in Figure 1 , apparatus 100 according to certain embodiments of the present invention for continuous powder-based additive manufacturing of parts includes a transporter 102, such as a belt, chain, conveyor, platform, or the like, which defines a closed loop transport path. As illustrated in Figure 1 , the closed loop transport path extends around a horizontal axis. The transport path as illustrated in Figure 1 is substantially rectangular in plan profile having curved corner regions, however the transporter may define other continuous closed loop shapes, such as oval, circular, square, or the like.

The transporter 102 supports at least one build bed, preferably as illustrated a plurality of build-beds 104, and is controlled by the controller 1 12. Each build bed 104 is coupled to the transporter 102 which is driven by suitable means, such as an electric motor operably coupled to a controller 1 12, such that the build beds are moved along the continuous transport path in a carousel-type manner. In other words, the build beds are separable from the transporter, i.e. the build beds can be removed / replaced from the transporter.

For example, each build bed may be coupled to a driven belt or chain or other suitable conveyor element which defines the closed loop transport path. Alternatively, each build bed may be configured to drive itself with respect to the transporter along the transport path. For example, each build bed may comprise a drive assembly coupled to the transporter, wherein each drive assembly includes a driven gear coupled to a toothed rack of the transporter.

As illustrated in Figure 2, each build bed 104 is a substantially rectangular box-like container having an open top 105 and includes a rectangular-shaped building platform 107 therein for supporting powder for additively manufacturing at least one AM part 150. The building platform 107 may be located above a base of the container or may be the base itself. The platform is movable along the Z axis, i.e. up and down, by suitable means, e.g. a motor and scissor jack or piston arrangement, and such movement is controlled by the controller 1 12.

The apparatus 100 further includes a plurality of printing units, e.g. conventional printing units, arranged above the build beds 104 as they travel along the transport path.

In the illustrated embodiment, the plurality of printing units are fixed at a predetermined height relative to the build beds 104 when preparing or energising the surface of the powder material supported thereon.

The powder supporting platform of each build beds is controllably moveable between a first position and a second position for adjusting the height of the powder material supported on the powder supporting platform relative to the plurality of printing units.

In alternative embodiments, the plurality of printing units may also be controllably moveable between a first position and a second position for adjusting the height of the powder material supported on the powder supporting platform relative to the plurality of printing units. Typically, the plurality of printing units are controllably moveable along a vertical (Z) axis.

The printing units aptly include at least one powder surface preparation unit 106 for preparing a powder surface in the or each build bed 104, such as by dispensing, rolling, scraping, or the like. The printing units aptly include at least one energy emitting unit 108, e.g. an infra-red lamp or a laser system for powder sintering/fusing, and at least one curing unit 1 10 to cure an additively manufactured part/s by suitable means such as dispensing an agent/binder/solvent or the like.

The function of the curing unit may vary according to the type of sintering technology used and the functional requirement of the produced AM parts. A wide variety of chemicals may be used on the sintered polymer parts to provide them with various mechanical or aesthetical properties. For example, a chemical agent may be sprayed onto the sintered parts to strengthen them. In another example, an organic solvent that can dissolve the polymer material may be sprayed on the parts to slightly dissolve and smoothen the surface. The curing unit may spray a colour pigment on to the sintered material for aesthetic purposes. In exemplary embodiments, an additional curing unit may be included before the sintering/fusing unit 108 but after the powder dispensing unit 106. This additional curing unit may be used to dispense an infra-red light absorbing agent on to the powder bed to aid the sintering process. The agent is deposited on specific areas of the powder layer to define the geometry of the parts. Once the thermal energy source is emitted onto the powder under the sintering/fusing unit 108, the powder sinters in the places where the agent was deposited and remains un-sintered/un-processed where the agent is absent.

The printing units are controlled by the controller 1 12 which also controls the speed and direction of the build-beds 104 along the transport path. The controller 1 12, such as a programmable logic controller (PLC), may be connected to the Internet or another computer system to receive and store commands and information, and configured to control the printing units, build beds and transporter via a wired or wireless connection. As illustrated in Figure 3, the or each build bed 104 moves along the transport path in the direction of arrow A and under an energy emitting device 310 of the energy emitting unit 106, e.g. a laser, heat lamp or other thermal energy emitting device. The speed of movement of the build bed along the transport path with respect to the energy emitting device 310 is controlled by the controller 1 12. The speed of movement may correspond to the properties of the powder material being used in the build bed and/or the complexity of the part being printed and/or the type of energy emitting device, e.g. laser or infrared lamp. In exemplary embodiments, there may be additional units for dispensing powder, curing and/or emitting energy. In exemplary embodiments, multiple units may be positioned along the transport path to further increase the efficiency and speed of the printing process. For example, as illustrated in Figure 4, the energy emitting/powder fusing section of the apparatus may comprise a number of sintering units 408,409 arranged in parallel to thereby increase the efficiency and throughput of the apparatus. A build bed 402 is controllably moved along an input transport path on which a surface preparation unit 406 is located which prepares/dispenses powder on the print bed. The build bed 402 is then selectively moved to a first sintering unit 408 or a second sintering unit 409 before being moved along an output transport path on which a curing unit 410 is located. Such an arrangement may include two or more sintering paths each having a sintering unit located thereon to allow at least one layer of a plurality of AM parts in different build beds to be printed at the same/similar time.

In exemplary embodiments, the apparatus may be enclosed in a controlled environment, involving regulated pressure, temperature and/or an inert gas. An inert gas environment may be used to prevent the powder material, e.g. nylon, oxidising when heated by the laser beam. The temperature inside the build chamber/build bed may be kept relatively high but below the melting point of the un-sintered powder, e.g. around 170°C for nylon, so that the temperature increase required by the laser to fuse the powder surface particles is relatively low. In exemplary embodiments, there may be temperature, pressure and/or other sensors located in the build chambers/beds for monitoring and controlling the AM process. In exemplary embodiments, the apparatus may be integrated into a system comprising additional units/modules for positioning, removing and post-processing additively manufactured components.

An alternative apparatus 500 according to certain embodiments of the present invention is illustrated in Figures 5a and 5b. The apparatus 500 includes a substantially circular/annular build/print bed 504 which is fixed in terms of rotational movement about its central axis. The build bed is configured to contain powder for additively manufacturing at least one AM part therein. A vertically oriented shaft 502 extends upwardly from the centre of the build bed 504 and supports a powder surface preparation unit 506, an energy emitting unit 508 and a curing unit 510 each of which radially extend outwardly from the shaft 502 and are circumferentially spaced apart from each other by around 120 degrees. The angular spacing between adjacent units may be equal or different and may be greater or less than 120 degrees. The spacing will of course depend on the number of printing units present. The shaft 502 is rotatably driven about its axis by a motor operably controlled by a controller to thereby rotate each unit with respect to the rotationally fixed print bed in a desired rotational direction (anticlockwise in the illustrated example). Alternatively, the shaft may be rotationally fixed and the print bed may controllably rotate with respect to the printing units which radially extend from the shaft.

The powder surface preparation unit 506 may include a number of nozzles for dispensing/layering/depositing/rolling/scraping (or the like) powder across the width of the build-bed from R1 to R2 as shown in Figure 5c. In the curved arc shaped sections of the build-bed, the surface preparation rate, e.g. rate of dispensing/layering of the powder, may vary across the width of the build-bed to ensure uniform powder coverage. In the case powder is dispensed/layered using nozzles, the dispensing rate of each nozzle depends on its location along the circular shaped build-bed and follows equation (1 ) below incorporating the length of the circle and angle radius: rate = c [k2nR_x{6 + 360)]/360 (1 ) where k is the standard dispensing rate at 0° angle, Rx is the location of the particular nozzle along the line between R2 and R1 , which are the radii of the two imaginable circles composed out of each side of the build-bed wall as shown in Figure 5c, Q is the radius of the circular shaped build-bed at which the nozzle is located at the particular point in time, and c is the experimentally derived rate adjustment coefficient to help tune the dispensing rate. In the case powder is prepared on the surface in another way, including but not limited to rolling, scraping or depositing, similar circle length and angle radius-based equation is used to adjust for the uniformity of the powder layer.

The powder dispensing/layering rate is calculated by the controller 1 12, which tracks the location of every nozzle along the circular build-bed section. The same relationship may be used for the energy emitting unit 508 and the curing unit 510.

The energy emitting unit 508 comprises at least one energy source, e.g. a heat lamp, laser or other thermal energy emitting device, mounted on a boom coupled to the transport shaft 502. The energy source may be controllably movable along the boom to thereby energise predetermined locations of the powder bed responsive to a geometry of the part being created. Alternatively, a plurality of spaced apart energy sources may be mounted on the boom and selectively operated to energise predetermined locations of the powder bed under a respective one of the energy sources responsive to a geometry of the part being created. In a similar manner, the curing unit 510 may comprise at least one nozzle selectively movable along its respective boom for spraying an agent on the powder bed. Alternatively, a plurality of nozzles may be mounted on the boom to dispense a curing agent on predetermined locations on the powder bed responsive to a geometry of the part being created.

Aptly, each unit 504,506,508 is controllably moveable along the shaft, i.e. along the Z axis, to thereby adjust the height of the respective unit with respect to the print bed, e.g. to accommodate a new layer of powder provided by the powder surface preparation unit 506 during the printing process. Alternatively, the print bed 504 may include an annular shaped platform for supporting the powder and which is moveable in the Z-axis, e.g. it is lowered by a distance corresponding to the thickness of a new powder layer each time new powder is dispensed on the powder bed during printing. Aptly, a new powder layer is provided and a new layer of the AM part created for each revolution. The process is continued until the desired AM part is complete.

A method 600 of continuous powder-based additive manufacturing will now be described with reference to the flow diagram of Figure 6 and the apparatus of Figure 1 .

At step 602, powder is prepared/deposited in a first one of the build/print beds 104 by the surface preparation/powder dispensing unit 106. A variety of different powder materials can be used, including various polymers, metals and ceramics. The powder surface preparation unit 106 is configured to provide a new layer of powder across the width of the build platform within the build bed. As each build bed 104 is moved under the powder surface preparation unit, the powder is layered substantially across the build platform of the build bed. The speed of the build bed 104 with respect to the powder surface preparation unit 106, the rate of powder deposition on to the build bed, and the start/end time of the powder deposition are controlled by the controller 1 12. After a new layer of powder has been prepared, the first build bed then moves along the transport path and a trailing build bed takes its place for powder layer preparation. At the start of the printing process, the building platform within each build bed is positioned at the top or in an upper portion of the build bed. After the powder layer has been prepared in the build bed, the build platform is controllably lowered by a distance corresponding to a thickness of the new powder layer. After each successive layer preparation, the build platform moves down until the part being additively manufactured has been formed, as illustrated in Figure 2. The extent of movement in the Z direction depends on the required layer thickness of the part and is controlled by the controller.

At step 604, the first build bed 104 is moved to the energy emitting unit 108 where the powder layer deposited/prepared at step 602 is energised, e.g. sintered by a laser, heat lamp or other energy emitting unit. During sintering, just enough energy is emitted such that the powder fuses together to form a layer of the desired part. The emitted energy depends on the type of material to be sintered and the sintering technology. A number of sintering technologies may be used for the sintering process, both for polymer and metal, including but not limited to powder bed inkjet printing, selective laser sintering, binder jetting, direct metal laser sintering, multi jet fusion, high speed sintering, electron-beam melting, and material jetting, or the like. The AM parts may be made from polymers including but not limited to Nylons (Nylon™12 (PA220 Duraform™ PA), Nylon™1 1 (Duraform™ EX Natural, Duraform™ EX Black), Glass Filled Nylon™ (Duraform™ GF), Durable Nylon™ (Duraform™ EX), Fiber-filled Nylon™ (Duraform™ FIST) or the like), Thermoplastic Polyurethane (TPU), TPEelastomer materials, PMMA , ABS, EDPM, NBR, PC, PP, PPS, PVDF, ULTEM™ 9085, ULTEM™ 1010, PEEK or the like.

In the case of Selective Laser Sintering (SLS), the build bed 104 comes to a standstill and the laser of the sintering unit 108 selectively fuses a predefined area of the powder. In exemplary embodiments, the build bed 104 may continue moving while the laser sinters the powder and the laser is controllably adjusted to follow the build- bed. The energy, movement and speed of the laser is controlled by the controller 1 12.

In the case of inkjet printing (or powder bed sintering), there may be an additional curing/binding stage/s before the sintering stage 108. This is to spray an agent on the powder bed to aid the sintering process and define the geometry of the parts. The inkjet unit, for example as illustrated in Figure 3, is fixed and the build bed moves under it at a speed selected by the controller. In exemplary embodiments, there may be several inkjet spraying heads/units positioned over the build bed. At step 606, the first build bed 104 is moved to a curing unit 1 10 where the fused powder layer is cured. The specifics of this step depend on the type of powder being used and the desired objective. For the case of polymer printing, step 606 may also involve a solvent being sprayed on a formed AM part to dissolve and smooth the surface of the part. This step may also involve spraying a dye on to the fused layer or formed AM part to provide the same with a desired colour.

The movement of the build beds following one another is synchronized by the controller 112 to ensure optimum operation. At step 608, the platform of the build bed 104 is moved downwardly in the Z direction to accommodate the creation of the new powder layer. The thickness of the layer, and therefore the amount of movement in Z direction, depends on the specified part design requirements and is controlled by the controller 1 12. In the case of the alternative embodiment of the apparatus as illustrated for example in Figures 5a and 5b, the powder dispensing unit 106, the sintering/energy emitting unit 108, and the curing unit 1 10 would each independently be moved upwardly in a direction parallel to the shaft axis to accommodate a new powder layer. At step 610, the build bed 104 starts another cycle around the closed loop and continuous transport path with a new powder layer being deposited at and by the dispensing unit 106.

At step 612, the process is repeated until the desired AM part/s have been formed and/or finished.

Certain embodiments of the present invention therefore provide an improved apparatus and method for efficiently and continuously manufacturing AM parts using a powder-based additive manufacturing process. Unlike conventional AM sintering apparatus which rely on sintering units which move back and forth over a print bed and come to rest after each stroke (which undesirably limits printing output and increases wear on moving parts), the apparatus according to certain embodiments of the present invention is configured to provide a smooth, efficient and continuous AM process which increases printing output whilst reducing wear on moving parts, undesirable NVH effects, costly downtime for maintenance/repair, and also energy usage.

Claims

1. An apparatus for additively manufacturing a part, the apparatus comprising:

at least one powder surface preparation device for preparing a surface of powder material supported on at least one of said build beds; and

at least one energy emitting device for energising a powder surface prepared on at least one of said build beds based on a desired part geometry, wherein the plurality of build beds are controllably moveable along a closed loop transport path, and

wherein the closed loop transport path extends around a horizontal axis.

2. The apparatus according to claim 1 , wherein the plurality of build beds are supported on a transporter which defines the closed loop transport path.

3. The apparatus according to claim 2, wherein the plurality of build beds are separable from the transporter.

4. The apparatus according to any preceding claim, wherein movement of the plurality of build beds along the closed loop transport path is controlled by a controller based on the desired part geometry and/or the powder material and/or the energy emitting device.

5. The apparatus according to any preceding claim, wherein the powder supporting platform of each of the plurality of build beds is controllably moveable between a first position and a second position for adjusting a height of said powder supporting platform.

6. The apparatus according to claim 5, wherein the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above the powder support platform of at least one of said build beds when preparing or energising the surface of the powder material, and wherein the powder supporting platform of said build beds is controllably moveable between a first position and a second position for adjusting a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

7. The apparatus according to any preceding claim, wherein the at least one powder surface preparation device and/or the energy emitting device is controllably moveable between a first position and a second position for adjusting a height of the at least one powder surface preparation device and/or the energy emitting device.

8. The apparatus according to claim 7, wherein the apparatus is configured such that the at least one powder surface preparation device and/or the energy emitting device are located above the powder support platform of at least one of said build beds when preparing or energising the surface of the powder material supported by said build beds, and wherein the at least one powder surface preparation device and/or the energy emitting device is controllably moveable between a first position and a second position for adjusting a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

9. The apparatus according to any preceding claim, further comprising at least one curing device located on the closed loop transport path, upstream and/or downstream of the at least one energy emitting device for curing the powder material before or after the powder material has been energised.

10. An additive manufacturing system comprising the apparatus according to any preceding claim.

1 1. A method of additively manufacturing a part, comprising:

preparing a surface of the powder material supported on at least one of said build beds by at least one powder surface preparation device; controllably moving the plurality of build beds along a closed loop transport path, the closed loop transport path extending around a horizontal axis, and

12. The method according to claim 1 1 , wherein the plurality of build beds are supported on a transporter defining the closed loop transport path, and wherein the method further comprises removing at least one of the plurality of build beds from the transporter after the powder surface has been energised by the at least one energy emitting device.

13. The method according to claim 12, wherein the method further comprises replacing the at least one build bed on the transporter after the at least one build bed has been removed from the transporter.

14. The method according to claim 1 1 , 12 or 13, wherein the plurality of build beds are supported on a transporter defining the closed loop transport path, and wherein the method further comprises placing an additional build bed onto the transporter.

15. The method according to any of claims 1 1 to 14 comprising:

moving the plurality of build beds along the closed loop transport path based on the desired part geometry and/or the powder material and/or the energy emitting device.

16. The method according to any of claims 1 1 to 15, further comprising:

moving the powder supporting platform of at least one of said build beds between a first position and a second position so as to adjust a height of said powder supporting platform.

17. The method according to claim 16, further comprises: locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path whilst preparing or energising the surface of the powder material, and

moving the powder supporting platform of at least one of said build beds between a first position and a second position so as to adjust a clearance between the powder material and the at least one powder surface preparation device and/or the energy emitting device.

18. The method according to any of claims 1 1 to 17, further comprising:

moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to adjust a height of the at least one powder surface preparation device and/or the energy emitting device.

19. The method according to claim 18, further comprises:

locating the at least one powder surface preparation device and/or the energy emitting device above the closed loop transport path whilst preparing or energising the surface of the powder material, and

moving the at least one powder surface preparation device and/or the energy emitting device between a first position and a second position so as to adjust a clearance between the powder material supported and the at least one powder surface preparation device and/or the energy emitting device.

20. The method according to any of claims 1 1 to 19, comprising:

curing the powder material by at least one curing device located on the closed loop transport path upstream and/or downstream of the at least one energy emitting device.

21. The method according to any of claims 1 1 to 20, comprising:

moving the plurality of build beds around the transport path a plurality of times until the desired part has been formed.

22. The method according to any of claims 1 1 to 21 , wherein energising comprises laser sintering/fusing.

23. The method according to any of claims 1 1 to 22, wherein the powder material comprises Nylon.

24. An apparatus for additively manufacturing a part, comprising:

at least one energy emitting device for energising the powder surface prepared on at least one of said build beds based on a desired part geometry, wherein the plurality of build beds are controllably moveable along a closed loop transport path, and

wherein the at least one powder surface preparation device and the energy emitting device are controllably moveable along the closed loop transport path for accessing at least one of the plurality of build beds.

25. A method of additively manufacturing a part, comprising:

controllably moving the plurality of build beds along a closed loop transport path;