WO2021154223A1

WO2021154223A1 - Moveable vibration unit

Info

Publication number: WO2021154223A1
Application number: PCT/US2020/015530
Authority: WO
Inventors: Pablo Antonio MURCIEGO RODRIGUEZ; Wojciech Jerzy KRASOWSKI; Arturo GARCIA GOMEZ
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-01-29
Filing date: 2020-01-29
Publication date: 2021-08-05

Abstract

A station (2) is provided to receive one or more parts printed by an additive manufacturing system. The station (2) has a vibration unit (4) with an element (6) to receive the one or more parts and to vibrate the one or more parts received, a base (8) on which the element is mounted, and at least one elastically resilient member (10) with which the element is mounted to the base to allow relative movement between the base (8) and element (6). A drive arrangement (12) is coupled to the base (8) to move the vibration unit (4).

Description

MOVEABLE VIBRATION UNIT

BACKGROUND

[0001] Additive manufacturing machines produce 3D objects by building up layers of material. Some additive manufacturing machines are commonly referred to as "3D printers". 3D printers and other additive manufacturing machines make it possible to convert a CAD (computer aided design) model or other digital representation of an object into the physical object. The model data may be processed into slices each defining that part of a layer or layers of build material to be formed into the object. Build material may comprise any suitable form of build material, for example fibres, granules or powders. The build material can include thermoplastic materials, ceramic material and metallic materials.

BRIEF DESCRIPTION OF THE DRAWINGS

[0002] Some non-limiting examples of the present disclosure will be described in the following with reference to the appended drawings in which:

[0003] Figure 1 is a schematic cross-sectional view of a station according to a first example wherein an element is located in a first position;

[0004] Figure 2 is a schematic cross-sectional view of the station of Figure 1 wherein the element is located in a second position;

[0005] Figure 3 is a perspective view of a station according to a second example;

[0006] Figure 4 is a perspective cross-sectional view of the station of Figure 3 wherein a vibratory element is located in a first position;

[0007] Figure 5 is a front cross-sectional view of the station of Figure 3 wherein the vibratory element is located in the first position;

[0008] Figure 6 is a front cross-sectional view of the station of Figure 3 wherein the vibratory element is located in a second position;

[0009] Figure 7 is a perspective cross-sectional view of the vibratory element of the station of Figure 3; and

[0010] Figure 8 is a front cross-sectional view of a vibration drive arrangement of the station of Figure 3. DETAILED DESCRIPTION

[0011] In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific examples in which the disclosure may be practiced. It is to be understood that other examples may be utilised and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims. It is to be understood that features of the various examples described herein may be combined, in part or whole, with each other, unless specifically noted otherwise.

[0012] In some additive manufacturing processes, a binder or fusing agent is used to bind or fuse together particles of a powdered build material to form a solid object. The printing begins with a process of spreading the powdered build material on to the surface of a build platform. Binder or fusing agent is then jetted at precise locations on to each formed layer of powder to define the geometry of the single or multiple parts to be printed. This process is repeated to form the part or parts layer by layer. Energy, such as heat or light may be applied to each powder layer to cause solidification of a binder agent, or to cause thermal fusion of powder on which a fusing agent is applied.

[0013] Build material may comprise any suitable form of build material, for example short fibres, granules or powders. A powder may include short fibres that may, for example, have been cut into short lengths from long strands or threads of material. The build material can include thermoplastic materials, ceramic material and metallic materials. In examples, fusing agent is used. In other examples, binding agent is used. Binding agents may include chemical binder systems, such as in binder jet or metal binder jet type 3D printing. The present disclosure is applicable to any suitable build materials. The present disclosure is applicable when fusing or binding agent is used, as mentioned above. [0014] After the printing process, the single or multiple parts which have been printed are subjected to post-processing, which includes a process of removing coalesced build material (non-fused/non-bound or partially fused/bound build material) from the part or parts. This process is known as “de-caking”. The examples shown in the accompanying drawings are used in a de-caking process in respect of single or multiple parts produced by any type of additive manufacturing system.

[0015] With reference to the accompanying drawings, Figures 1 and 2 show a station 2 to receive one or more parts (not shown) printed by an additive manufacturing system. The station 2 has a vibration unit 4 having an element 6 to receive the one or more parts and to vibrate the one or more parts received, a base 8 on which the element 6 is mounted, and at least one elastically resilient member 10 with which the element 6 is mounted to the base 8 to allow relative movement between the base 8 and element 6. The station 2 also has a drive arrangement 12 coupled to the base 8 to move the vibration unit 4.

[0016] In the example of Figure 1 , the or each elastically resilient member is provided as a helical spring. More specifically, one elastically resilient member 10 is provided and is provided as a helical spring. In another example, four helical springs are provided, with each helical spring being located on the element 6 at a different corner of a square or rectangle. The use of the or each elastically resilient member allows the element 6 to be subjected to vibration without a potentially negative impact of this vibration being transmitted to the base 8 and the drive arrangement 12 coupled to the base 8. The element 6 can be vibrated at many different frequencies and amplitudes in order to assist in dislodging and removing non-fused/non-bounnd or partially fused/bound build material from the part or parts located on the element 6. Simultaneously, the vibration unit 4 can be moved by the drive arrangement 12. The or each elastically resilient member 10 ensures that the effect of varying frequencies and amplitudes of vibration on the base 8 and the drive arrangement 12 is considerably reduced from that which would be the case if the element 6 was mounted directly to the base 8 without the or each elastically resilient member and without the possibility of relative movement between the base 8 and element 6. The resilient nature of the or each elastically resilient member 10 allows the member 10 to deform from a resting position without being damaged, and to do so many times. The elastic nature of the or each elastically resilient member 10 allows the member 10 to be restored back to the resting position by a restoring force inherent in the material of the member 10 and arising from the deformation of the material. The use of the or each elastically resilient member 10 has little or no adverse effect of the ability to vibrate the element 6 at different frequencies and amplitudes, and allows movement of the base 8 with the drive arrangement 12 without significant vibration being transmitted to the drive arrangement 12.

[0017] The vibration unit 4 has a vibration drive arrangement 14 mounted to the element 6 of the vibration unit 4. In an example, the vibration drive arrangement has two unbalanced rotors and a motor to rotate each rotor. A control arrangement is provided to coordinate rotation of the rotors to produce a net vibratory movement vertically back and forth along one linear axis within a chamber of the station. The unbalanced nature of each rotor produces a vibration when each rotor is rotated and, by coordinating the rotation of the two rotors, the vibratory movement of the one rotor can cancel the vibratory movement of the other rotor in all but two opposite directions (for example, up and down). The rotation of the rotors can be coordinated so that the rotors rotate as a mirror image of one another i.e. they contra rotate with their unbalanced masses opposite one another. A net vertical vibration in the station 2 is thereby generated. A horizontal or sideways vibratory movement is minimised or avoided in this way, which avoids repeated impact of the element 6 on components to the side of the element 6, for example, the sides of the station 2.

[0018] The element 6 of the vibration unit 4 is a platform having a plurality of apertures 16,18 extending therethrough to provide fluid communication with a fluid extraction system 20. In an example, the vibration drive arrangement provides a net vibratory force acting through, or approximately through, the centre of gravity of the component or group of components it is to vibrate (for example, the platform). This ensures the vibratory force generates a linear movement of the component or group of components without, or with minimal, also generating a rotatory movement of the component or group of components. [0019] The fluid extraction system 20 has a reservoir 22 for receiving build material, and wherein the vibration unit 4 further has a fluid passageway 24 located between the element 6 and the base 8 to direct fluid and build material from the plurality of apertures 16,18 to the reservoir 22 of the fluid extraction system 20. The element 6 and the base 8 are spaced from one another by the or each elastically resilient member 10 and the fluid passageway 24 is located in this space between the element 6 and the base 8. The relative movement between the element 6 and the base 8 may be restricted so as to avoid movement of the element 6 and base 8 towards each other tending to reduce the space between the element 6 and the base 8, and damaging or interfering with the fluid passageway 24. Movement between the element 6 and the base 8 may be restricted using abutting stop elements (not shown) mounted on one or both of the element 6 and base 8.

[0020] The drive arrangement 12 is configured to move the vibration unit 4 vertically within a chamber 26 of the station (as indicated by arrow 28). In the example of Figures 1 and 2, the drive arrangement has one linear actuator 30 to selectively move the vibration unit 4 up and down between an upper position and a lower position. The vibration unit 4 is shown in the upper position in Figure 1 and in the lower position in Figure 2.

[0021] In another example, the drive arrangement 12 has three linear actuators operable independently of one another to selectively move the vibration unit up and down between upper and lower positions. The drive arrangement 12 also operates to tilt the vibration unit. This may be achieved by extending the linear actuators by different extents so that the platform is rotated from the plane in which it is originally located.

[0022] The station 2 also has a cleaning device 32 to clean build material from the one or more parts received by the vibration unit 4. In one example the cleaning device 32 has one or more air knives.

[0023] The drive arrangement 12 is configured to move the vibration unit 4 between a first position (see Figure 1), in which a cleaning zone of the cleaning device is collocated with the element of the vibration unit to clean one or more parts received by the element, and a second position (see Figure 2), in which the element is spaced from the cleaning zone of the cleaning device.

[0024] Also shown in Figures 1 and 2 is a non-transitory computer-readable storage medium 34 having computer executable instructions which, when executed by a processor 36, cause a station 2 of an additive manufacturing system to perform a method. The method vibrates an element 6 of a vibration unit 4 in the station 2, the element 6 receives one or more parts; and moves a base 8 of the vibration unit 4 in the station 2, wherein the vibration unit 4 has at least one elastically resilient member 10 with which the element 6 is mounted to the base 8 to allow relative movement between the base 8 and element 6.

[0025] A controller 50 is provided to control the station 2. The non-transitory computer- readable storage medium 34 and processor 36 are provided by the controller 50. The controller 50 includes the control arrangement provided to coordinate rotation of the rotors. In an example, the control arrangement is provided by a mechanical connection which weds rotation of the rotors to one another.

[0026] In use of the station 2, one or more parts printed by an additive manufacturing system are transferred to the chamber 26 of the station 2. The one or more parts are located within a bed of non-fused/non-bound or partial fused/bound build material and the purpose of transferring them to the station 2 is to allow this build material to be removed from the or each part in a controlled way which contains and recycles the non-fused/non-bound build material. The bed of non-fused/non- bound build material, with the one or more parts located therein, is located on element 6. The vibration drive arrangement 14 is then operated to vibrate the element 6. The vibration of the element 6 is transferred to the bed of non- fused/non-bound build material which, as a result, is loosened from the one or more parts.

[0027] As non-fused/non-bound build material falls from the one or more parts, it is sucked through the plurality of apertures 16,18 extending through element 6 and extracted from the chamber 26 through the fluid passageway 24 for recycling. The fluid passageway 24 provides fluid communication between the apertures 16,18 and the fluid extraction system 20, which applies a pressure drop at the apertures 16,18 and pumps fluid from chamber 26. Build material received by the fluid extraction system 20 is held in a reservoir 22 of the fluid extraction system 20. This recycles build material may then be stored for subsequent reuse.

[0028] The drive arrangement 12 coupled to the base 8 is operated to move the vibration unit 4 vertically up and down within the chamber 26. The drive arrangement 12 is electrically, pneumatically or hydraulically operated. In the example of Figures 1 and 2, the drive arrangement 12 has a telescopic ram which is coupled to the base 8. The movement of the vibration unit 4 can occur simultaneously with the vibration of the element 6, or without the vibration of the element 6. The movement can assist in loosening non-fused/non-bound or partially fused/bound build material from the part or parts. The at least one elastically resilient member 10 substantially avoids or reduces the vibration of the element 6 being transmitted to the base 8 and the drive arrangement 12, and reduces the likelihood of damage to the drive arrangement 12 as a result of element 6 being vibrated. The vibration unit 4 is, therefore, a unit which has a vibrating element but which has a base 8 for connection with a component or components external to the vibration unit 4 which is isolated or at least partly isolated from the vibration generated by the vibration drive arrangement 14 mounted to the element 6.

[0029] The drive arrangement 12 moves the element 6 between first and second positions. In the first position, as shown in Figure 1 , the element 6 is adjacent the cleaning device 32 of the station 2 and thereby collocated in a cleaning zone of the cleaning device 32. In this way, the or each part on the element 6 is further cleaned of non-fused/non-bound or partially fused/bound build material which is then extracted to the reservoir 22. In the second position, as shown in Figure 2, the element 6 is spaced from the cleaning device 32 and from the cleaning zone.

[0030] The vibration unit 4 may be repeatedly moved up and down in the chamber 26 by the drive arrangement 12, and the element 6 and the parts located thereon may be repeatedly moved to the cleaning device 32. The or each part located on the element 6 can be repeated moved through the cleaning device (air knife) to promote a loosening of non-fused/non-bound or partially fused/bound build material.

[0031 ] The drive arrangement 12 may also be configured to tilt the vibration unit 4, and hence the element 6, within the chamber 26. This movement may be made while the element 6 is being vibrated and can assist in removing further non-fused/non- bound or partially fused/bound build material from the or each part. The tilting of the vibration unit 4 can result in the or each part rolling on the element 6 and this can itself assist with removal of build material form the or each part, for example, by exposing different aspects of the or each part to the cleaning device 32.

[0032] Once the part or parts have been cleaned satisfactorily, they are removed from the chamber 26. This may be done with the vibration unit 4 located in a lower position within the chamber 26.

[0033] A station 2’ of an additive manufacturing system in accordance with aspects of the present disclosure is shown in Figure 3. Components of this station 2’ and the operation thereof is described below with reference to Figures 3 to 7. The station 2’ has features corresponding to those of the schematic station shown in Figures 1 and 2, and corresponding features are denoted with like reference numerals in the accompanying drawings. By way of example, the schematic station of Figures 1 and 2 has a fluid extraction system 20, and the system of Figures 3 to 7 has a fluid extraction system 20’.

[0034] In Figures 3 to 7, apparatus 100 is shown as having a station 2’ of an additive manufacturing system and a controller 50’ to control the station 2’. A non-transitory computer-readable storage medium and processor are provided by the controller 50.

[0035] The station 2’ has a drive arrangement 12’ and a vibration unit 4’ having a base 8’, an element 6’ and at least one elastically resilient member 10’ with which the element 6’ is mounted to the base 8’ to allow relative movement between the base 8’ and element 6’. [0036] The controller 50' operates the station 2’ to actuate the vibration unit 4’ of the station 2’ to vibrate the element 6’ of the vibration unit 4’, and actuate the drive arrangement 12’ of the station 2’ to move the base 8’ of the vibration unit 4’ in the station 2’.

[0037] The controller 50’ operates the station 2’ to move the base 8’ between a first position (see Figure 5), in which a cleaning zone of a cleaning device 32’ of the station 2’ is collocated with one or more parts (not shown) received by the element 6’ to clean the one or more parts, and a second position (see Figure 6) in the station 2’, in which the one or more parts are spaced from the cleaning zone of the cleaning device 32’.

[0038] The controller 50’ selectively operates the station 2’ to vibrate the element 6’ while in the first position to remove loose build material located on and around one or more parts received by the element 6’, and to vibrate the element 6’ while in the second position to remove loose build material located on and around one or more parts received by the element 6’.

[0039] Furthermore, the controller 50’ actuates the drive arrangement 12’ to tilt the base 8’ and change the orientation of one or more parts received by the element 6’ relative to the station 2’.

[0040] The controller 50’ operates the station 2’ to extract fluid and loose build material from around one or more parts received by the element 6’. The fluid and loose build material is extracted through a passageway 24’ extending between the base 8’ and element 6’.

[0041] The vibration unit 4’ has a vibration drive arrangement 14’ which is located below a central region of the element 6’. This allows a net vibratory force generated by the vibration drive arrangement 14’ to be conveniently directed through, or approximately through, the centre of gravity of the component or group of components it is to vibrate (i.e. the element 6’). This ensures the vibratory force generates a linear up and down movement of the element 6’ within the chamber 26’ without, or with minimal, rotatory movement of the element 6’.

[0042] The vibration drive arrangement 14’ has two vibramotors 60,62 (see Figure 8). Each vibramotor has an unbalanced rotor (not shown) and a motor (not shown) to rotate each rotor. Each rotor is rotated in a coordinated manner producing a net vibratory movement back and forth along one linear axis 68. This linear axis 68 is oriented in line with the longitudinal axis of a chamber 26’ of the station 2’. In use, the linear axis 68 is vertically oriented and so the vibration drive arrangement 14’ generates a vertical vibratory movement.

[0043] The unbalanced nature of each rotor produces a vibration when each rotor is rotated. As indicated above, by coordinating the rotation of the two rotors, the vibratory movement of one rotor cancels the vibratory movement of the other rotor in all but two opposite directions (for example, up and down). The rotation of the rotors is coordinated so that the rotors rotate as a mirror image of one another i.e. they contra rotate with their unbalanced masses remaining opposite one another. A net vertical vibration in the station 2 is thereby generated in use, and vibratory movements in other directions (for example, a horizontal or sideways vibratory movement) are minimised or avoided. This avoids repeated impact of the element 6’ on the sides of the chamber 26’.

[0044] The vibration drive arrangement 14’ is mounted to the central region of the element 6’. The base 8’ has an opening through which the vibration drive arrangement 14’ extends. The fluid passageway 24’ extends from the element 6’ either side of the vibration drive arrangement 14’.

[0045] In use of the apparatus 100, one or more parts printed by an additive manufacturing system are transferred to the chamber 26’ of the station 2’. The one or more parts are located within a bed of non-fused/non-bound or partially fused/bound build material which is itself transferred to the station 2’ in an enclosed box 102. The bottom of the box is removable by sliding. When the box 102 is position on the station 2’ above the chamber 26’, the bottom of the box is slid to one side allowing the one or more parts and surrounding cake of non-fused/non- bound or partially fused/bound build material to fall on to the element 6’ below.

[0046] A user/control interface screen 104 allows a user to enter control instructions to the controller 50’ and to also receive information from the controller 50’.

[0047] The element 6’ of the station 2’ is provided as a planar platform which is provided with a first plurality 16’ of apertures extending therethrough and a second plurality 18’ of apertures extending therethrough (see Figure 7). The fluid extraction system 20’ has a reservoir 106 for receiving build material which has been extracted through the pluralities 16’, 18’ of apertures and fluid passageway 24’, and also has two centrifugal separators located on top of the reservoir 106 to separate build material from the mixture of air and build material flowing through the fluid passageway 24’.

[0048] The platform 6’ is moved up and down in the chamber 26’ by the extension and retraction of three linear actuators 30’ in the form of electrically operated rams. In another example, the drive arrangement 12’ has hydraulically or pneumatically operated rams. In the first position (see Figure 5), the one or more parts on the platform 6’ are subjected to the cleaning effect of the cleaning device 32’. The cleaning device 32’ has four air knives, each on an opposing wall of the chamber 26’. The three linear actuators 30’ may be operated independently of one another and differentially to tilt the platform 6’ and thereby assist with removal of the non- fused/non-bound or partially fused/bound build material from the one or more parts.

[0049] In the second position (see Figure 6), the one or more parts on the platform 6’ are not subjected to the cleaning effect of the cleaning device 32’.

[0050] The element 6’ is vibrated to impart a vibration to the one or more parts. This vibration promotes a loosening of the non-fused/non-bound or partially fused/bound build material from the one or more parts and encourages the build material to fall from the one or more parts. The element 6’ may be vibrated at different frequencies and amplitudes. [0051] The at least one elastically resilient member 10’ is provided as four separate helical springs extending between the element 6’ and the base 8’. The springs allow the element 6’ to vibrate, moving predominantly up and down relative to the base 8’. The stiffness of the springs and the vibration frequency and excitation force applied to the element 6’ is selected to ensure vibratory movements transferred to the base 8’ and then to the linear actuators 30’ are minimal or within acceptable limits for the linear actuators 30’, preserving the operational condition and life of the actuators 30’.

[0052] Although specific examples have been illustrated and described herein, a variety of alternate and/or equivalent implementations may be substituted for the specific examples shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific examples discussed herein. Therefore, it is intended that this disclosure be limited by the claims and the equivalents thereof.

Claims

1. A station to receive one or more parts printed by an additive manufacturing system, the station comprising: a vibration unit comprising an element to receive the one or more parts and to vibrate the one or more parts received, a base on which the element is mounted, and at least one elastically resilient member with which the element is mounted to the base to allow relative movement between the base and element; and a drive arrangement coupled to the base to move the vibration unit.

2. The station of claim 1, wherein the or each elastically resilient member is a helical spring.

3. The station of claim 2, wherein the vibration unit comprises a vibration drive arrangement mounted to vibrate the element of the vibration unit.

4. The station of claim 3, wherein the vibration drive arrangement comprises two unbalanced rotors, a motor to rotate each rotor, and a control arrangement to coordinate rotation of the rotors to produce a net vibratory movement vertically back and forth along one linear axis within a chamber of the station.

5. The station of claim 1 , wherein the element of the vibration unit is a platform comprising a plurality of apertures extending therethrough to provide fluid communication with a fluid extraction system.

6. The station of claim 5, further comprising a fluid extraction system having a reservoir for receiving build material, and wherein the vibration unit further comprises a fluid passageway located between the element and the base to direct fluid and build material from the plurality of apertures to the reservoir of the fluid extraction system.

7. The station of claim 1 , wherein drive arrangement is configured to move the vibration unit vertically within a chamber of the station.

8. The station of claim 1 , wherein the drive arrangement comprises three linear actuators operable independently of one another to selectively move the vibration unit up and down between upper and lower positions and to tilt the vibration unit.

9. The station of claim 1 , further comprising a cleaning device to clean build material from the one or more parts received by the vibration unit, wherein the cleaning device comprises one or more air knives, and wherein drive arrangement is configured to move the vibration unit between a first position, in which a cleaning zone of the cleaning device is collocated with the element of the vibration unit to clean one or more parts received by the element, and a second position, in which the element is spaced from the cleaning zone of the cleaning device.

10. Apparatus comprising a station of an additive manufacturing system and a controller to control the station, the station comprising a drive arrangement and a vibration unit comprising a base, an element and at least one elastically resilient member with which the element is mounted to the base to allow relative movement between the base and element, the controller operating the station to: actuate the vibration unit of the station to vibrate the element of the vibration unit, and actuate the drive arrangement of the station to move the base of the vibration unit in the station.

11 .The apparatus of claim 10, wherein the controller operates the station to move the base between a first position, in which a cleaning zone of the cleaning device of the station is collocated with one or more parts received by the element to clean the one or more parts, and a second position in the station, in which the one or more parts are spaced from the cleaning zone of the cleaning device.

12. The apparatus of claim 11 , wherein the controller selectively operates the station to vibrate the element while in the first position to remove loose build material located on and around one or more parts received by the element, and to vibrate the element while in the second position to remove loose build material located on and around one or more parts received by the element.

13. The apparatus of claim 10, wherein the controller actuates the drive arrangement to tilt the base and change the orientation of one or more parts received by the element relative to the station.

14. The apparatus of claim 10, wherein the controller operates the station to extract fluid and loose build material from around one or more parts received by the element, the fluid and loose build material being extracted through a passageway extending between the base and element.

15. A non-transitory computer-readable storage medium comprising computer executable instructions which, when executed by a processor, cause a station of an additive manufacturing system to perform a method, the method comprising: vibrating an element of a vibration unit in the station, the element to receive one or more parts, moving a base of the vibration unit in the station, wherein the vibration unit comprises at least one elastically resilient member with which the element is mounted to the base to allow relative movement between the base and element.