Hopper

Abstract

A hopper (1) for a binder jetting machine (2), comprising a housing wall (3) defining a containment compartment (4) therein for containing binder jetting powders (5), wherein the housing wall (3) forms at least one loading opening (6) for loading the powders (5) into the containment compartment (4) of the hopper (1), and at least one dispensing opening (7) for dispensing the powders (5) from the containment compartment (4) out of the hopper (1), wherein the hopper (1) comprises a partition wall (8) positioned inside the containment compartment (4) and configured to divide the containment compartment (4) into at least a first containment compartment (4') and a second containment compartment (4") separated from each other, and wherein the hopper (1) comprises a selective closing device (9) interposed between the containment compartment (4) and the dispensing opening (7), wherein the selective closing device (9) is configured to selectively close the first containment compartment (4') or the second containment compartment (4").

Description

“HOPPER”

[0001] Field of the invention

[0002] The present invention relates to a hopper, in particular a hopper installable in a binder jetting machine.

[0003] Background art

[0004] Binder jetting is an additive production technology that uses a bed of powders. It consists in depositing drops of liquid binder for selectively joining the powder particles to create mesh-shaped parts, which are then subjected to a sintering process. The process, repeated layer on layer, is used to create three-dimensional items.

[0005] Contrarily to many common additive production technologies using a heat source to melt together raw materials or light to selectively harden a liquid crosslinking, binder jetting glues the particles to form the geometry layer by layer so that heat is not required during the manufacturing. Moreover, the unbound powder temporarily supports disconnected portions of the component, allowing the formation of internal volumes.

[0006] Moreover, binder jetting technology can be adapted to almost all powders, with high production rates and little raw material waste, which makes it particularly promising for the luxury field, for example, for making jewelry.

[0007] Binder jetting technology is performed by means of binder jetting machines which generally comprise a printing plane on which a powder bed is deposited and distributed by means of a hopper. Binder jetting machines further comprise a printing head for releasing minuscule drops of binder onto the powder bed and a system for moving the printing plane configured to cyclically lower the printing plane in order to repeat the process of depositing the powders and dispensing the liquid binder.

[0008] Although it is promising and advantageous, binder jetting technology still has various drawbacks.

[0009] One drawback of binder jetting technology is due to the complexity or impossibility of printing three-dimensional items made with different materials or colors, which are particularly required for making jewelry and various items of the luxury field.

[0010] Therefore, the need is felt to provide an improved binder jetting machine compared to the machines of the prior art.

[0011] Solution

[0012] It is the object of the present invention to provide a binder jetting machine which solves the drawbacks of the prior art.

[0013] It is a particular object of the present invention to provide a binder jetting machine which allows easily and quickly printing three-dimensional items made with different materials or colors.

[0014] This and other objects are achieved by a hopper for a binder jetting machine, and by a binder jetting machine, according to the independent claims.

[0015] The dependent claims relate to preferred and advantageous embodiments of the present invention.

[0016] Figures

[0017] In order to better understand the invention and appreciate the advantages thereof, some non-limiting exemplary embodiments thereof will be described below with reference to the accompanying drawings, in which:

[0018] - Figure 1 is a diagrammatic perspective view of a binder jetting machine according to an embodiment of the invention;

[0019] - Figure 2 is a perspective view of a hopper for a binder jetting machine according to an embodiment of the invention;

[0020] - Figure 3 is a diagrammatic front view of a hopper for a binder jetting machine according to an embodiment of the invention;

[0021] - Figure 4 is a longitudinal-section side view of the hopper depicted in Figure 3;

[0022] - Figure 5 is a front view of the hopper depicted in Figure 3, in a first operating position;

[0023] - Figure 6 is a front view of the hopper depicted in Figure 3, in a second operating position.

[0024] Description of some preferred embodiments

[0025] With reference to the figures, a hopper is generally indicated by reference numeral 1 .

[0026] Hopper 1 is particularly adapted to be installed in a binder jetting machine 2, i.e., a machine or apparatus configured to perform 3D printing by means of binder jetting technology.

[0027] Hopper 1 comprises a housing wall 3.

[0028] The housing wall 3 defines a containment compartment 4 therein.

[0029] The containment compartment 4 is adapted to contain powders 5, in particular powders 5 adapted to perform binder jetting technology.

[0030] The housing wall 3 forms at least one loading opening 6. The loading opening 6 is configured to allow loading the powders 5 into the containment compartment 4 of hopper

[0031] Moreover, the housing wall 3 forms at least one dispensing opening 7. The dispensing opening 7 is configured to allow dispensing the powders 5 from the containment compartment 4 out of hopper 1 .

[0032] According to an aspect of the invention, hopper 1 comprises a partition wall 8.

[0033] The partition wall 8 is positioned inside the containment compartment 4.

[0034] Moreover, the partition wall 8 is configured to divide the containment compartment 4 into at least a first containment compartment 4’ and a second containment compartment 4”.

[0035] The first containment compartment 4’ and the second containment compartment 4” are separated from each other.

[0036] Moreover, hopper 1 comprises a selective closing device 9.

[0037] The selective closing device 9 is interposed between the containment compartment 4 and the dispensing opening 7.

[0038] Moreover, the selective closing device 9 is configured to selectively close the first containment compartment 4’ or the second containment compartment 4”.

[0039] Advantageously, the hopper 1 thus configured allows easily and quickly printing three-dimensional items with different materials or colors.

[0040] In fact, the hopper 1 thus configured allows storing binder jetting powder materials 5 with different materials or colors in the at least a first containment compartment 4’ and a second containment compartment 4” so that they are separated from each other, and selectively dispensing the powders 5 contained in the first containment compartment 4’ or the powders contained in the second containment compartment 4”, by means of the selective closing device 9 configured to selectively close one of the two containers and simultaneously leave the other of the two containers open, thus allowing them to be dispensed.

[0041] According to an embodiment, the first containment compartment 4’ and the second containment compartment 4” each define a discharging opening 10.

[0042] The discharging opening 10 is in fluid communication with the dispensing opening 7 of hopper 1 . Preferably, the discharging opening 10 of the first and second containment compartments 4’, 4” faces the dispensing opening 7 of hopper 1.

[0043] According to an embodiment, the selective closing device 9 is positioned at the discharging openings 10 of the first and second containment compartments 4’, 4” so as to selectively close the discharging opening 10 of the first containment compartment 4’ or the discharging opening 10 of the second containment compartment 4”.

[0044] According to an embodiment, the discharging opening 10 of the first containment compartment 4’ is separated from the discharging opening 10 of the second containment compartment 4” by the partition wall 8.

[0045] According to an embodiment, the selective closing device 9 comprises a shutter door 11.

[0046] The shutter door 11 is configured to selectively close the discharging opening 10 of the first containment compartment 4’ or the discharging opening 10 of the second containment compartment 4”. The shutter door 11 is thus capable of preventing the powders 5 contained in the respective closed containment compartment 4’, 4” from flowing through the dispensing opening 7.

[0047] According to an embodiment, the shutter door 11 is hinged to the partition wall 8 by means of a hinge 12.

[0048] The shutter door 11 is rotatable about the hinge 12 so as to close the discharging opening 10 of the first containment compartment 4’ and simultaneously leave the discharging opening 10 of the second containment compartment 4” open, or close the discharging opening 10 of the second containment compartment 4” and simultaneously leave the discharging opening 10 of the first containment compartment 4’ open.

[0049] Specifically, the shutter door 11 is rotatable between a first closing position, in which it closes the discharging opening 10 of the first containment compartment 4’ and simultaneously leaves the discharging opening 10 of the second containment compartment 4” open, and a second closing position, in which it closes the discharging opening 10 of the second containment compartment 4” and simultaneously leaves the discharging opening 10 of the first containment compartment 4’ open.

[0050] According to an embodiment, the shutter door 1 1 is configured to rotate between the first closing position and the second closing position by means of a rotation in an alternating direction. By way of example, the shutter door 11 is movable from the first to the second closing position by means of a counterclockwise rotation with respect to hinge 12, and vice versa, it is movable from the second to the first closing position by means of an opposite rotation in the clockwise direction with respect to hinge 12. Therefore, the selective closing device 9 is preferably not configured to rotate the shutter door 1 1 by 360° with respect to hinge 12, but rather to rotate the shutter door 11 by 180° with respect to hinge 12, with an alternating rotation direction.

[0051] According to an embodiment, the shutter door 11 is rotatable about a rotation axis 13 defined by hinge 12. The rotation axis 13 is substantially transverse to a dischargingdirection of the powders 5 from the first and second containment compartments 4’, 4”, and substantially parallel to the partition wall 8.

[0052] According to an embodiment, hopper 1 comprises at least two end-of-stroke walls 18 positioned at the hinge 12, preferably opposite to hinge 12. One of the two end-of- stroke walls 18 is positioned at the first containment compartment 4’ and the other of the two end-of-stroke walls 18 is positioned at the second containment compartment 4”.

[0053] The end-of-stroke walls 18 are configured to stop the rotation of the shutter door 11 about the hinge 12. The end-of-stroke walls 18 thus act as an end-of-stroke for the shutter door 11 so that the abutment between the shutter door 1 1 and the respective end- of-stroke wall 18 corresponds to a complete closing of the respective discharging opening 10 of the first or second containment compartment 4’, 4” by the shutter door 11.

[0054] According to an embodiment, the selective closing device 9 comprises an actuation system 14.

[0055] The actuation system 14 is configured to move the shutter door 11 , preferably rotationally about the hinge 12.

[0056] According to an embodiment, the actuation system 14 is connected to hopper 1 , preferably it is connected outside hopper 1 , at the housing wall 3.

[0057] According to an embodiment, the actuation system 14 comprises an electric motor 15 and a transmission 16.

[0058] The transmission 16 is mechanically connected to the electric motor 15 and the shutter door 11 .

[0059] Specifically, transmission 16 is configured to transmit a movement originating from the electric motor 15 to the shutter door 1 1 .

[0060] A rotation of a drive shaft of the electric motor 15 thus corresponds to a rotation of the shutter door 1 1 with respect to hinge 12.

[0061] According to an embodiment, the electric motor 15 is a stepper motor.

[0062] According to an embodiment, transmission 16 comprises a clutch 17.

[0063] Clutch 17 is interposed between the shutter door 1 1 and the electric motor 15.

[0064] Clutch 17 is configured to allow an uncoupling between the electric motor 15 and the shutter door 11 .

[0065] Advantageously, clutch 17 prevents the electric motor 15 from being damaged or broken. In fact, the rotation of the shutter door 1 1 required to completely close a discharging opening 10 may not correspond to an integer multiple of steps of the electric stepper motor 15. Such a non-correspondence can cause either an incomplete closing of the discharging opening 10 or an abutment between the shutter door 1 1 activated by theelectric motor 15 against the respective end-of-stroke wall 18, which could lead to the electric motor 15 being damaged or broken. The shutter door 1 1 abutting against a respective end-of-stroke wall 18 can be uncoupled from the electric motor 15 by means of clutch 17, preventing damage to the electric motor 15.

[0066] According to an embodiment, clutch 17 comprises two clutch wheels 19 facing and abutting each other, and kinematically coupled by friction, in particular static friction. One of the two clutch wheels 19 is kinematically directly connected to the electric motor 15 while the other of the two clutch wheels 19 is kinematically directly coupled to the shutter door 11 .

[0067] The two clutch wheels 19 are configured so that, upon exceeding a predetermined limit friction torque, in particular a limit static friction, the two clutch wheels 19 slide with respect to each other, uncoupling the shutter door 1 1 from the electric motor 15. In particular, the two clutch wheels 19 slide with respect to each other, generating dynamic friction.

[0068] Advantageously, such a predetermined limit friction torque corresponds to an abutment torque acting on the electric motor 15 that is lower than a critical torque value of the electric motor 15, which could damage the electric motor 15.

[0069] According to an embodiment, hopper 1 comprises a filter wall 20.

[0070] The filter wall 20 is positioned at the discharging opening 10 of the first and second containment compartments 4’, 4”.

[0071] The filter wall 20 is configured to prevent a discharge of the powders 5 from the first and second containment compartments 4’, 4” in the absence of a movement of hopper 1.

[0072] According to an embodiment, the filter wall 20 is positioned substantially coplanar to the discharging opening 10, transverse to the partition wall 8.

[0073] According to an embodiment, hopper 1 comprises an ultrasound shaker 21 .

[0074] The ultrasound shaker 21 is connected to hopper 1 . Preferably, the ultrasound shaker 21 is connected to the housing wall 3. The ultrasound shaker 21 is configured to shake hopper 1 by means of an ultrasound vibration.

[0075] Advantageously, powder 5 can cross the filter wall 20 and be dispensed through the dispensing opening 7 by means of the ultrasound vibration actuated by the ultrasound shaker 21 .

[0076] With added advantage, the hopper 1 thus configured allows dispensing the powders 5 in a controlled manner. In fact, during a rotation of the shutter door 1 1 from a first to a second closing position, both the discharging openings 10 of the first and secondcontainment compartments 4’, 4” remain open until the shutter door 11 reaches its end- of-stroke, completely closing a respective discharging opening 10. Advantageously, the filter wall 20 prevents powder 5 from passing through the respective discharging openings 20 during the period in which both discharging openings 10 are open so as to prevent an undesired discharge of powder 5.

[0077] With added advantage, when the shutter door 11 completely closes one of the two discharging openings 10 and the selective dispensing of the powders 5 contained in the individual open containment compartment 4’, 4” is required, such a dispensing is actuated by actuating the ultrasound shaker 21 , which shakes hopper 1 , in particular the housing wall 3, so as to bias the powders 5 contained in the open containment compartment 4’, 4” to come out so that the powders 5 pass through the filter wall 20.

[0078] According to an embodiment, the housing wall 3 of hopper 1 is made of a polymer material, preferably transparent polymer material.

[0079] According to an embodiment, the dispensing opening 7 is in the shape of a slit substantially parallel to the partition wall 8.

[0080] According to an embodiment, the loading opening 6 is formed facing the dispensing opening 7, and is formed opposite to the dispensing opening 7 with respect to the selective closing device 9.

[0081] According to an embodiment, the partition wall 8 extends between a first end, positioned at the loading opening 6, and an opposite second end, positioned at discharging openings 10. Hinge 12 is positioned at the second end of the partition wall 8 so that a shutter door 11 is rotatable about the second end of the partition wall 8.

[0082] According to an embodiment, transmission 16 is made of a polymer material.

[0083] According to an embodiment, hopper 1 comprises an electronic processing unit configured to control the selective closing device 9.

[0084] According to an embodiment, powder 5 contained in hopper 1 is powder of a gold alloy, preferably 18k, even more preferably of the “18K5N” type. According to an embodiment, powder 5 is suitable for the 3D printing of jewelry.

[0085] According to an embodiment, the hopper 1 described above is insertable into binder jetting machine hoppers. Advantageously, the hopper 1 described above allows retrofitting binder jetting machines, giving such machines the possibility to selectively dispense powders 5 with different materials or colors, and therefore making three- dimensional items with different materials or colors.

[0086] According to an embodiment, the housing wall 3 has a box-like shape.

[0087] According to an embodiment, the housing wall 3 comprises a tapered wall 22. The tapered wall 22 is tapered in the direction of the dispensing opening 7. Advantageously, the tapered wall 22 reduces the volumes of hopper 1 and simplifies the insertion of hopper 1 into further hoppers for retrofitting operations.

[0088] According to an embodiment, the selective closing device 9 is positioned inside the tapered wall 22.

[0089] According to an embodiment, the shutter door 11 is positioned inside the tapered wall 22.

[0090] According to a further aspect of the invention, a binder jetting machine 2 comprises a hopper 1 as described above. Hopper 1 is configured to cyclically deposit and distribute a bed of powders 5 on a printing plane 23 of machine 2.

[0091] Obviously, those skilled in the art will be able to make changes or adaptations to the present invention, without however departing from the scope of the following claims.REFERENCE NUMERALS1 . Hopper2. Machine3. Housing wall4. Containment compartment4’. First containment compartment4”. Second containment compartment5. Powders6. Loading opening7. Dispensing opening8. Partition wall9. Selective closing device10. Discharging opening11 . Shutter door12. Hinge13. Rotation axis14. Actuation system15. Electric motor16. Transmission17. Clutch18. End-of-stroke wall19. Clutch wheel20. Filter wall21 . Ultrasound shaker22. Tapered wall23. Printing plane

Claims

CLAIMS1. A hopper (1 ) for a binder jetting machine (2), comprising a housing wall (3) defining a containment compartment (4) therein for containing binder jetting powders (5), wherein the housing wall (3) forms at least one loading opening (6) for loading the powders (5) into the containment compartment (4) of the hopper (1 ), and at least one dispensing opening (7) for dispensing the powders (5) from the containment compartment (4) out of the hopper (1 ), wherein the hopper (1 ) comprises a partition wall (8) positioned inside the containment compartment (4) and configured to divide the containment compartment (4) into at least a first containment compartment (4’) and a second containment compartment (4”) separated from each other, and wherein the hopper (1 ) comprises a selective closing device (9) interposed between the containment compartment (4) and the dispensing opening (7), wherein the selective closing device (9) is configured to selectively close the first containment compartment (4’) or the second containment compartment (4”).

2. A hopper (1) according to claim 1 , wherein the first containment compartment (4’) and the second containment compartment (4”) each define a discharging opening (10) in fluid communication with the dispensing opening (7) of the hopper (1 ), and wherein the selective closing device (9) is positioned at the discharging openings (10) of the first and second containment compartments (4’, 4”) so as to selectively close the discharging opening (10) of the first containment compartment (4’) or the discharging opening (10) of the second containment compartment (4”), and wherein, preferably, the discharging opening (10) of the first containment compartment (4’) is separated from the discharging opening (10) of the second containment compartment (4”) by the partition wall (8).

3. A hopper (1 ) according to claim 2, wherein the selective closing device (9) comprises a shutter door (11 ) configured to selectively close the discharging opening (10) of the first containment compartment (4’) or the discharging opening (10) of the second containment compartment (4”) so as to prevent the powders (5) contained in the respective closed containment compartment (4’, 4”) from flowing through the dispensing opening (7).

4. A hopper (1 ) according to claim 3, wherein the shutter door (1 1 ) is hinged to the partition wall (8) by means of a hinge (12), wherein the shutter door (11 ) is rotatable about the hinge (12) so as to close the discharging opening (10) of the first containment compartment (4’) and simultaneously leave the discharging opening (10) of the second containment compartment (4”) open, or close the discharging opening (10) of the second containment compartment (4”) and simultaneously leave the discharging opening (10) of the first containment compartment (4’) open.

5. A hopper (1 ) according to claim 3, comprising at least two end-of-stroke walls (18) positioned at the hinge (12), wherein one of the two end-of-stroke walls (18) is positioned at the first containment compartment (4’) and the other of the two end-of-stroke walls(18) is positioned at the second containment compartment (4”), and wherein the end-of- stroke walls (18) are configured to stop the rotation of the shutter door (1 1 ) about the hinge (12) so that the abutment between the shutter door (1 1 ) and the respective end- of-stroke wall (18) corresponds to a complete closing of the respective discharging opening (10) of the first or second containment compartment (4’, 4”) by the shutter door (11 ).

6. A hopper (1 ) according to claim 3, wherein the selective closing device (9) comprises an actuation system (14) configured to move the shutter door (11 ), wherein the actuation system (14) comprises an electric motor (15) and a transmission(16) mechanically connected to the electric motor (15) and to the shutter door (1 1 ), wherein the transmission (16) is configured to transmit a movement originating from the electric motor (15) to the shutter door (11 ), and wherein the electric motor (15) is a stepper motor.

7. A hopper (1 ) according to claim 6, wherein the transmission (16) comprises a clutch(17) interposed between the shutter door (1 1 ) and the electric motor (15), wherein the clutch (17) is configured to allow an uncoupling between the electric motor (15) and the shutter door (1 1 ).

8. A hopper (1 ) according to claim 7, wherein the clutch (17) comprises two clutch wheels(19) facing and abutting each other, and kinematically coupled by friction, wherein one of the two clutch wheels (19) is kinematically directly connected to the electric motor (15) while the other of the two clutch wheels (19) is kinematically directly coupled to theshutter door (11 ), and wherein the two clutch wheels (19) are configured so that, upon exceeding a predetermined limit friction torque, the two clutch wheels (19) slide with respect to each other, uncoupling the shutter door (1 1 ) from the electric motor (15).

9. A hopper (1 ) according to claim 2, comprising a filter wall (20) positioned at the discharging opening (10) of the first and second containment compartments (4’, 4”), wherein the filter wall (20) is configured to prevent a discharge of the powders (5) from the first and second containment compartments (4’, 4”) in the absence of a movement of the hopper (1 ), wherein the hopper (1 ) further comprises an ultrasound shaker (21 ) configured to shake the hopper (1 ) by means of an ultrasound vibration.

10. A hopper (1 ) according to any one of the preceding claims, wherein the housing wall (3) is made of transparent polymer material, and / or wherein the dispensing opening (7) is in the shape of a slit substantially parallel to the partition wall (8), and / or wherein the loading opening (6) is formed facing the dispensing opening (7) and is formed opposite to the dispensing opening (7) with respect to the selective closing device (9), and / or wherein the partition wall (8) extends between a first end, positioned at the loading opening (6), and an opposite second end, positioned at discharging openings (10), wherein a hinge (12) is positioned at the second end of the partition wall (8) so that a shutter door (1 1 ) is rotatable about the second end of the partition wall (8), and / or wherein a transmission (16) is made of polymer material, and / or wherein the hopper (1 ) comprises an electronic processing unit configured to control the selective closing device (9), and / or wherein the housing wall (3) comprises a tapered wall (22) in the direction of the dispensing opening (7), and / or wherein the hopper (1 ) is insertable into binder jetting machine hoppers.

11. A binder jetting machine (2), comprising a printing plane (23) and a hopper (1 ) according to any one of the preceding claims, wherein the hopper (1 ) is configured to cyclically deposit and distribute a bed of powders (5) on the printing plane (23).

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