Device and method for constructing a layer body

Abstract

The invention relates to a device for constructing a laminar body from a plurality of superimposed layers of free-flowing material, in particular particulate material, and a build platform within a working area. The layers are solidified in locally predetermined regions by the action of binders and are joined together so that at least one moulded body is formed by the solidified and joined regions of the layers. The device comprises a discharging device movable back and forth over the working area in at least one discharge direction and having at least one discharge opening from which the free-flowing material can be discharged in individual superimposed layers during the movement of the discharging device.

Claims

1. A method for constructing a layered body comprising: i. applying individual layers of a free-flowing material on a first portion of a build platform; ii. selectively printing a binder for forming the layered body and one or more printed walls at least partially surrounding the layered body; wherein a second portion of the build platform does not receive the free-flowing material; wherein excess free-flowing material is discharged or conducted outside the printed wall.

2. The method of claim 1, wherein the layered body is constructed without a build container.

3. The method of claim 1, wherein an action of the binder solidifies and joins together the free-flowing material in predetermined areas, optionally wherein the binder is selectively applied by a print head.

4. The method of claim 1, wherein the build platform is stationary, the free-flowing material is applied by a discharge device, and the method includes increasing the height of the discharge device by one layer thickness after applying one of the individual layers for applying another one of the individual layers.

5. The method of claim 4, wherein the discharge device applies the free-flowing material while moving in a forward direction and while moving in a reverse direction.

6. The method of claim 1, wherein the one or more printed walls surround the layered body.

7. The method of claim 4, wherein the discharge device has an elongated opening for applying each layer of the free-flowing material in one pass.

8. A method for constructing a layered body comprising: i. applying individual layers of a free-flowing material on a first portion of a build platform; ii. selectively fusing the free-flowing material for forming the layered body and one or more walls at least partially surrounding the layered body; wherein a second portion of the build platform does not receive the free-flowing material; wherein excess free-flowing material is discharged or conducted outside the printed wall.

9. The method of claim 8, wherein the layered body is constructed without a build container.

10. The method of claim 8, wherein the method includes a step of irradiating the free-flowing material to solidify and join together the layers of the free-flowing material in predetermined areas.

11. The method of claim 8, wherein the build platform is stationary, the free-flowing material is applied by a discharge device and the method includes increasing the height of the discharge device by one layer thickness after applying one of the individual layers for applying another one of the individual layers.

12. The method of claim 11, wherein the discharge device applies the free-flowing material while moving in a forward direction and while moving in a reverse direction.

13. The method of claim 8, wherein the one or more printed walls surround the layered body.

14. The method of claim 11, wherein the discharge device has an elongated opening for applying each layer of the free-flowing material in one pass.

15. A device for forming a layered-body comprising: i) a build platform upon which the layered body is constructed; ii) a discharge device having an elongated slot, for layer-wise applying a free-flowing material on the build platform in a build space; and iii) a print head or a radiation source for selectively joining the free-flowing material for forming the layered-body; wherein a length of the elongated slot is changed for varying a size of the build space.

16. The device of claim 15, wherein the discharge device applies the free-flowing material while moving in a forward direction and while moving in a reverse direction.

17. The device of claim 15, wherein the discharge device applies each layer of the free-flowing material in one pass.

18. The device of claim 15, wherein the device is free of a build container.

19. A method comprising the steps of: i) forming a layered body using the device of claim 15, by repeatedly discharging layers of the free-flowing from the discharge device on a portion of the build platform, and selectively joining the free-flowing material using the print head or the radiation source; and ii) removing loose particle material.

20. The method of claim 19, wherein the method includes changing a length of the discharge slot for forming a different layered body.

21. A method for constructing a layered body comprising: i. applying individual layers of a free-flowing material on a first portion of a build platform; ii. selectively printing a binder for forming the layered body and one or more printed walls at least partially surrounding the layered body; wherein a second portion of the build platform does not receive the free-flowing material.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) Exemplary embodiments of the invention are illustrated below in the drawing and explained in greater detail in the following description. In the drawing,

(2) FIG. 1 shows a top view of a device for producing moldings with different build space sizes on a build platform.

(3) FIGS. 2a through 2d show a schematic cross-sectional view of a device for producing moldings according to one preferred embodiment of the invention.

(4) FIGS. 3a through 3g show a schematic cross-sectional view of another embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a preferred embodiment of a device 13 for constructing a layer body 5 from a plurality of superimposed layers of, for example, powdered, initially loose, particulate material on a build platform 6 within a build space 11a through 11d.

(6) Build spaces 11a through 11d of different sizes illustrated in FIG. 1 extend over a wide area in FIG. 1 parallel to build platform 6 in the horizontal X and Y directions, layer body 5 being constructed in the vertical Z direction, which is perpendicular to the drawing plane in FIG. 1.

(7) Device 13 comprises a discharging device 1 which is movable back and forth over build space 11a through 11d in at least one discharge direction, in this case, for example, in the X direction and/or the Y direction, discharging device 1 having at least one discharge opening 14, which is not visible in this view and from which the particulate material may be discharged in individual superimposed layers during the movement of discharging device 1.

(8) Discharging device 1 is preferably a non-switchable discharging device, i.e., without the option of turning the material flow through discharge opening 14 on and off, so that free-flowing material or particulate material may or may not flow out. Instead, particulate material continuously flows through discharge opening 14 in discharging device 1 unless discharge opening 14 is closed by means belonging to discharging device 1 or if no (more) particulate material is present in a reservoir of discharging device 1.

(9) Device 13 furthermore comprises a print head 2 which is moveable back and forth over build space 11, for example, in the X and Y directions for the selective application of binder onto at least one discharged layer in order to solidify and join together discharged layers in locally predetermined areas of build space 11a through 11d by the action of binders, so that at least one molding 4 is formed by the solidified and joined areas of the layers of layer body 5 in a known manner.

(10) Alternatively, print head 2 could be replaced with a radiation source if the discharged, free-flowing material already contains a binder which is then hardened by selective irradiation with the radiation source for the purpose of creating molding 4. Or the free-flowing material itself is fused or slightly melted by the irradiation and joined thereby.

(11) The extension of build space 11a through 11d in the X and Y directions is predefined by the application of material to build platform 6, different sizes of build spaces 11a through 11d being illustrated in FIG. 1. If build space 11a through 11d is described in the illustrated orthogonal coordinate system 9, each extension or size of build spaces 11a through 11d may be displayed as a rectangle, starting from origin 10. The dimensions of build platform 6 in the X and Y directions then correspond to a maximum displayable size of one build space 11a.

(12) One rectangular side of a build space 11 of this type is generally determined, for example, by the discharge route or discharge travel of discharging device 1 in discharge direction X, so that, in the present case, the size of the build space is dependent on the length of this discharge route. Based on the example in FIG. 1, the discharge route of discharging device 1 thus increases from 11d to 11a in the X direction.

(13) The other rectangular side of a build space 11a through 11d is determined, for example, by the width of discharge opening 14 of discharging device 1 in the Y direction, which may be formed, in particular, by an elongated slot. In the present case, different lengths of discharge openings 14 of discharging device 1 are provided to obtain the variable-length rectangular side of build spaces 11a through 11d in the Y direction. In the present case, therefore, one layer of layer body 5 may, on the whole, be completely produced in one pass of the discharge route in the X direction.

(14) Only one rectangular side of a build field 11 is visible in the cross-sectional side representation in FIGS. 2a through 2d and 3a through 3g. In these illustrations, the edges of build space 11 are preferably formed by printed walls 3 in the X and Y directions, i.e., the particulate material is selectively solidified here by print head 2 so that loose particulate material of layer body 5 located within the edges of build space 11 is not able to flow off in areas outside build space 11. For this purpose, print head 2 suitably prints the edge areas of each discharged layer. Alternatively, however, a separate build container or separate build walls could be used to delimit build space 11.

(15) In the embodiments illustrated herein, build platform 6 is preferably lowered as the height of layer body 5 increases in the Z direction, in particular using drives and guides which are not illustrated. Discharging device 1 therefore remains on its initial level for each new layer to be discharged and is therefore movable relative to build platform 6, for example only in the X direction and/or the Y direction. Alternatively, build platform 6 could be designed to be stationary, and at least discharging device 1 could be designed to be movable relative to stationary build platform 6 in both the X and Y directions as well as the Z direction.

(16) In the specific embodiments in FIGS. 2a through 2d and 3a through 3g, build platform 6 is vertically adjustable relative to, for example, two bodies 8, 8a delimiting the build space in discharge direction X of the discharging device according to the particular progression of construction, in such a way that surfaces of bodies 8, 8a facing discharge opening 14 of discharging device 1 are aligned flush with a topmost layer of layer body 5 yet to be produced or already produced.

(17) The purpose of the two bodies 8, 8a is to close discharge opening 14 of discharging device 1 and to prevent discharging device 1 from discharging free-flowing material (body 8) or to discharge free-flowing material that is not used for layering into a collecting container 7 (body 8a) when discharge opening 14 of discharging device 1 is located above particular body 8, 8a.

(18) At least one of bodies 8, 8a, in this case preferably body 8, is designed to be adjustable within a horizontal plane parallel to build platform 6 and, in particular, in the X direction, for the purpose of variably delimiting build space 11. The areal extension of build space 11 is then delimited by body 8 at least in the X direction, in particular when the position of body 8 is designed to be movable in discharge direction X of discharging device 1.

(19) Build platform 6 is therefore particularly preferably designed to be adjustable relative to bodies 8, 8a, discharging device 1 and print head 2 in the vertical Z direction, and body 8, discharging device 1 and print head 2 are designed to be movable relative to build platform 6 in the horizontal X direction. The position of body 8 is adjusted in the X direction in order to flexibly adapt build space 11 to the particular requirements and, in particular, to the one or more moldings 4 to be constructed, while minimizing losses of free-flowing material.

(20) The two bodies 8, 8a are consequently always on the same level in the Z direction, in particular through attachment to or guidance on a stationary frame of device 13, which is not illustrated herein, while build platform 6 is being lowered as the construction of layer body 5 continues to progress.

(21) Bodies 8, 8a are preferably flat, plate-shaped bodies, for example metal plates with and without through-openings 12, depending on whether the particular body 8 or 8a is to prevent material from being discharged from discharge opening 14 of discharging device 1 or to permit or cause material to be discharged into collecting container 7. Body 8a is therefore preferably formed by a perforated plate having at least one through-opening 12. Body 8a may furthermore also comprise means for conducting particulate material into collecting container 7. Not least, at least one through-opening 12 of body 8a may be controllable, i.e., the at least one through-opening 12 may be opened or closed as a function of external electrical, pneumatic and/or mechanical control signals in order to discharge or conduct free-flowing material not used for layering from discharge opening 14 into collecting container 7 for the purpose of returning it to the layering process.

(22) As indicated above, discharging device 1 is displacement-controlled, for example, by an electronic control unit, which is not illustrated here, with regard to a predefined discharge route in the X direction, extending from an initial, starting or idle position 14 at one edge of build space 11 to a reversing position 16 at the opposite edge of build space 11; i.e., in response to a starting command, it first moves from its starting or idle position 14 in the X direction to reversing position 16, at which the direction of movement is automatically reversed, if necessary upon expiry of a certain dwell time at reversing position 16.

(23) During the movement of discharging device 1 along the discharge route, which simultaneously forms the length of the rectangular side of build space 11 visible herein, particulate material is preferably continuously applied to build platform 6 or to a previously layered part of layer body 5 via discharge opening 14.

(24) Prior to this, discharging device 1, which in this case is, for example, a discharging hopper of a filling device which is not illustrated herein but is easy to picture, is preferably filled with a quantity of particulate material corresponding to a multiple of layers to be applied.

(25) According to the embodiment in FIGS. 2a through 2d, starting position 15 is predefined by the position of body 8 adjustable in the X direction, while reversing position 16, at which body 8a is located, is stationary. In this case, the coating operation is started from the particular set position of body 8, body 8 closing discharge opening 14 of discharging device 1 precisely at starting position 15 and preventing particulate material from being discharged, as is easily pictured on the basis of FIG. 2a. Only after discharging device 1 has moved a distance from body 8 is free space the height or thickness of one layer provided below discharge opening 14, into which particulate material may be discharged to form a single layer. Specifically, the following method steps are carried out in the embodiment in FIGS. 2a through 2d:

(26) Build platform 6 is first positioned in the vertical direction relative to bodies 8 and 8a, to discharging device 1 and to print head 2, in such a way that the surfaces of body 8, 8a facing discharge opening 14, discharge opening 14 of discharging device 1 and print head 2 are disposed higher than the current topmost layer of layer body 5 by a distance of one layer thickness.

(27) When discharging device 1 is located in its starting position right above body 8, its discharge opening 14 is closed by body 8, as is easily pictured on the basis of FIG. 2a. Print head 2 is then preferably located on the far side of opposite reversing position 16 of discharging device 1, i.e., outside build space 11, in order to avoid colliding later on with discharging device 1 once it has reached reversing position 16.

(28) At the same time or thereafter, discharging device 1 is filled with free-flowing material at starting position 15 in a quantity sufficient to produce, for example, a single layer of layer body 5. The filling device, which is not illustrated herein, is then positioned, for example, above discharging device 1.

(29) The control unit then activates discharging device 1 so that it moves from starting position 15 to reversing position 16 while discharging particulate material to construct one layer. This situation is illustrated in FIG. 2a.

(30) When discharging device 1 has reached body 8a at reversing position 16, discharge opening 14 is located right above opened through-opening 12 in body 8a, so that any excess particulate material still remaining in discharging device 1 for producing a layer is able to flow into collecting container 7, which is disposed, for example, below through-opening 12 in body 8a. The control unit then returns emptied discharging device 1 to its starting position 15, whereby it is followed by print head 2 in order to provide or print binder onto a locally predetermined area of the discharged layer. Since discharging device 1 is empty during this movement, i.e., it is moved without particulate material, an unwanted application of particulate material to layer body 5 is avoided. This operation is illustrated in FIG. 2c.

(31) Once discharging device 1 has reached starting position 15, it is refilled with particulate material for one layer, and the described cycle begins all over again (FIG. 2d). The cycle according to FIGS. 2a through 2d are repeated until the entire layer body 5 is created. Print head 2 also prints the areas that represent walls 3 of layer body 5.

(32) In the specific embodiment illustrated in FIGS. 3a through 3g, in contrast to the specific embodiment in FIGS. 2a through 2d, reversing position 16 is determined by the position of body 8 set in the X direction, and starting position 15, where body 8a is located, is stationary. In this case, the coating operation is started at a stationary starting position 15, and reversing position 16 is defined depending on the position of body 8 in the X direction.

(33) Specifically, the following method steps are carried out in the embodiment in FIGS. 3a through 3g:

(34) Build platform 6 is first positioned vertically (in the Z direction) relative to bodies 8, 8a, to discharging device 1 and to print head 2, in such a way that, on the one hand, the surfaces of body 8, 8a facing discharge opening 14 and, on the other hand, discharge opening 14 are disposed higher than the current topmost layer of layer body 5 by a distance of one layer thickness. Body 8a, which has the at least one through-opening 12, and collecting container 7 located thereunder are positioned at starting position 15, and body 8, which does not have a through-opening 12 of this type, is positioned at reversing position 16.

(35) To prevent particulate material from flowing through through-opening 12 in body 8a into collecting container 7 in starting position 15, discharging device 1 is filled by a filling device, which is not illustrated herein, for example in a position located a short distance from starting position 15 in the X direction, in which a part of body 8a facing build space 11 is able to close discharge opening 14 in discharging device 1, as shown in FIG. 3g. Discharging device 1 is filled with particulate material for producing, for example, two layers of layer body 5.

(36) Print head 2 is located in the starting position, preferable on the near side of body 8a, so that it does not collide with discharging device 1. Discharging device 1 is then activated by the control unit in order to move from starting position 15 to reversing position 16 for the purpose of discharging particulate material in this matter to construct a layer (FIG. 3a). Once reversing position 16 at the edge of build space 11 has been reached, body 8 closes discharge opening 14 in discharging device 1. Print head 2 is subsequently activated by the control unit in order to print binder onto a locally determined area of the discharged layer as well as the areas that form walls 3 of layer body 5 (FIG. 3b). Afterwards, print head 2 returns to its starting position.

(37) Once a layer has been discharged and selectively printed, build platform 6 is lowered by a distance of one layer height or one layer thickness so that the surfaces of bodies 8 and 8a facing discharge opening 14, discharge opening 14 of discharging device 1 and print head 2 are again disposed higher than the current topmost layer of layer body 5 by a distance of one layer thickness.

(38) Discharging device 1 is then activated by the control unit in order to move from reversing position 16 back to starting position 15 while discharging particulate material for constructing another layer, as illustrated in FIG. 3c.

(39) After starting position 15 is reached, any particulate material that is not used for the two discharged layers may flow through the at least one through-opening 12 of body 8a into collecting container 7 (FIG. 3d).

(40) Print head 2 is subsequently activated so that it prints binder onto the areas of molding 4 and walls 3 of the additional discharged layer. Emptied discharging device 1 may then move in front of print head 2, as shown in FIG. 3e.

(41) According to FIG. 3f, discharging device 1 and print head 2 are moved back to their starting position 15 after the printing operation, build platform 6 preferably being simultaneously lowered by a distance of one layer height or one layer thickness for the purpose of making space in the vertical direction for a subsequent layering operation.

(42) After discharging device 1 has been refilled with particulate material in the position according to FIG. 3g, the described cycle begins all over again and is repeated until complete layer body 5 is created. Finally, loose particulate material is removed from the layer body in the unprinted areas, leaving molding 4 behind.

(43) Instead of lowering build platform 6 vertically relative to bodies 8, 8a, to discharging device 1 and to print head 2 as the construction continues to progress, bodies 8, 8a, discharging device 1 and the print head could, of course, also be designed to be movable relative to a stationary build platform 6 in the vertical Z direction, according to another embodiment.

LIST OF REFERENCE NUMERALS

(44) 1 Discharging device

(45) 2 Print head

(46) 3 Printed wall

(47) 4 Molding

(48) 5 Loose particulate material

(49) 6 Build platform

(50) 7 Collecting container

(51) 8 Body

(52) 8a Body

(53) 9 Coordinate system

(54) 10 Coordinate origin

(55) 11 Build space

(56) 12 Through-opening

(57) 13 Device

(58) 14 Discharge opening

(59) 15 Starting position

(60) 16 Reversing position