Method for producing a part using a deposition technique

Abstract

The invention relates to a method for producing a part using a deposition technique. A layered composite is built up in layers, the individual layers each containing particulate material and binding material as well as optionally, a treatment agent. The layers maintain a predetermined porosity. The layer composite is built up in the absence of hardening agent. Once construction is complete, the layer composite is hardened.

Claims

1. A method for producing a part using a deposition technique in layers by building a layered composite containing the part from particulate matter comprised of particles of a prescribed particle size, the method comprising steps of: depositing the particulate matter layer-by-layer to form successive layers of a porous bulk in a build location, and selectively apportioning a treatment agent in a predefined subarea of the layer prior to deposition of a subsequent layer, wherein the treatment agent is apportioned in a free-flowing state for setting up a bonding process, in which the particles in the predefined subarea bond firmly to one another, through a binder contained either in the particulate matter or deposited thereon, in the presence of an initiator, moving the layered composite to a different location; and bonding the particulate matter in the different location; whereby the building of the layered composite is done in the absence of an initiator, and the bonding process is executed only after completion of the layered composite, through addition of such initiator.

2. The method of claim 1, wherein the layered composite is in a same container during the building of the layered composite and during the bonding of the particulate matter.

3. The method of claim 1, wherein the predefined subarea of the layer is different from a predefined subarea of the subsequent layer.

4. The method of claim 1, wherein bonding of the particulate matter is in a single step at the different location.

5. The method of claim 1, wherein the binder is in the particulate material.

6. The method of claim 1, wherein the binder is in the treatment agent.

7. The method of claim 1, wherein the initiator is added in the different location.

8. The method of claim 1, wherein during the bonding of the layered composite, an additional layered composite is built in the build location.

9. The method of claim 1, wherein the particulate material is deposited with a deposition device having a coating blade.

10. The method of claim 9, wherein each layer of particulate material is deposited in a single pass of the deposition device over a building platform.

11. The method of claim 1, wherein the treatment agent is dispensed using an inkjet printer.

12. The method of claim 1, wherein loose particulate material is removed after the step of bonding.

13. The method of claim 1, wherein the subareas of adjacent layers at least partially overlap and the layers are firmly bound to each other in the regions of overlap.

14. The method of claim 13, wherein the layered composite is in a same container during the building of the layered composite and during the bonding of the particulate matter.

15. The method of claim 1, wherein bonding of the particulate matter is in a single step at the different location; the initiator is added in the different location; the particulate material is deposited with a deposition device having a coating blade; each layer of particulate material is deposited in a single pass of the deposition device over a building platform; the treatment agent is dispensed using an inkjet printer; loose particulate material is removed after the step of bonding; and the subareas of adjacent layers at least partially overlap and the layers are firmly bound to each other in the regions of overlap.

16. The method of claim 15, wherein the layered composite is in a same container during the building of the layered composite and during the bonding of the particulate matter.

17. The method of claim 16, wherein the predefined subarea of the layer is different from a predefined subarea of the subsequent layer.

18. The method of claim 17, wherein during the bonding of the layered composite, an additional layered composite is built in the build location.

19. The method of claim 18, wherein the binder is in the particulate material.

20. The method of claim 19, wherein the binder is in the treatment agent.

Description

(1) The preferred embodiment of the invention will now be explained in more detail with reference to the accompanying drawings, in which:

(2) FIG. 1a is a schematic sectional representation of a part produced according to a preferred embodiment of the invention through the application of a binder and/or treatment agent;

(3) FIG. 1b illustrates the fully completed part of FIG. 1a, and

(4) FIG. 2 shows a device for implementing the method according to the invention during operation of the dispensing head.

(5) FIG. 1a depicts a schematic sectional view of a part produced according to a preferred embodiment of the invention, such as a casting mould or core, through deposition of the binder, thereby illustrating the principle of the method. According to the method for building the part, a series of n layers are produced sequentially from s1 through sn. Accordingly, the first step involves depositing the first building layer s1 over the entire surface. In the next step, the binder and/or treatment agent are applied on a selected subarea t1 (hatched) of the first layer s1. These two steps are then repeated in sequence for the remaining layers s2 through sn. The subareas ti, tj for the different layers si, sj are generally different, but they at least overlap each other partially such that they are firmly bound to each other.

(6) Once the binder and/or treatment agent have been applied on the last layer, the entire part is flooded with the curing agent and thereby hardened. As a helpful measure, the layered composite can be evacuated prior to application of the curing agent. Finally, the loose building material lying outside of the areas t1 to tn is removed, resulting in the finished part shown in FIG. 1b.

(7) To produce a pattern with the method according to the invention, the building material is deposited as described above. Conversely, the binder and/or treatment agent are applied outside of the subareas ti, i=1 . . . n respectively. These areas outside ti are accordingly consolidated through final curing. Once the part has hardened, the loose particulate matter in the subareas ti, i=1 . . . n is removed, with the result that the remaining part reflects a hollow space in the shape of the body of FIG. 1b.

(8) A device for producing parts according to a preferred embodiment of the invention is shown in FIG. 2. Such a device is comprised of the following components:

(9) A vertically movable building platform 1, A control mechanism, A horizontally movable deposition device 2 steerable with the control mechanism, with which a packable building material can be deposited in layers on building platform 1 or on to a previous layer up to a prescribed layer thickness, and a horizontally movable dispensing head 3 arranged on a slide 42, which is steerable with the control mechanism and with which a liquid or particulate binder and/or treatment agent can be applied to a selected area of the layer.

(10) The building material deposition device 2 is arranged with a long box 21, open above and below, designed for receiving and depositing the building material on to building platform 1 and on to the last deposited layer. In the vicinity of the lower open edge of box 21 facing building platform 1 is an outlet device 22 with an opening that can be adjustably opened or closed and which is arranged with coating blades. Deposition device 2 is movable at a settable velocity perpendicularly to the long direction of box 21, as depicted by axis y in FIG. 2, from one end of building platform 2 and back.

(11) Slide 42 with dispensing head 3 for applying the binder is movable in a manner similar to the building material deposition device 2. Dispensing head 3 is movable perpendicularly, as depicted by axis x in FIG. 2, to the movement direction of slide 42, such that dispensing head 3 can be moved throughout the entire level above building platform 1.

(12) This method is implemented with the device according to a preferred embodiment of the invention, as follows.

(13) Deposition of Building Material Layers:

(14) On commencement of the procedure, deposition device 2 with box 21 filled with the building material, as shown in FIG. 2, is positioned at the initial edge of building platform 1. The outlet device 22 of box 21 is opened to deposit a strip of the building material. At the same time deposition device 2 is driven to the opposing edge of building platform 1 at a constant velocity, such that all of building platform 1 is covered with a uniform layer of the building material. Box 21 is thereby moved over building platform 1 in such a manner as to use its lower edge to smooth out the building material layer already deposited. The vertical position of building platform 1 with respect to box 21 is set such that the building material layer attains a predefined desired thickness, following smoothing out of the layer by the blade located on the lower edge of box 21. The velocity and/or the degree of opening of the deposition device 22 is accordingly preferably selected and set by the control mechanism such that precisely the amount of building material necessary to obtain the predefined layer thickness lands on building platform 1. As soon as deposition device 2 reaches the opposing edge of building platform 1, the material feeding process is interrupted.

(15) Application of the Binder and/or Treatment Agent:

(16) Dispensing head 3, preferably a Drop-On-Demand dispensing head known from inkjet printers, is moved along a prescribed path over building platform 1, through movement of slide 42 relative to building platform 1 and through movement of dispensing head 3 relative to slide 42. Simultaneously, dispensing head 3 ejects the binder and/or treatment agent. This leads to creation of a pattern with the binder and/or treatment agent in the building material layer, which reflects the part's cross-section through the layer level.

(17) The first layer is now complete and a second layer is to be deposited. Accordingly building platform 1 is moved a given distance downwards from the deposition device 2. A second layer of building material is then deposited and imparted a pattern with the binder and/or treatment agent.

(18) Additional layers are made in the same way until a layered composite is fully built.

(19) The layered composite is finally cured, preferably analogous to a conventional gas curing technique.

(20) For example, following deposition of the last layer and application of the binder on to this layer, the layered composite is removed from the deposition device. The building platform can be removed along with the layered composite to provide support thereto. The layered composite is then transferred, possibly with the building platform, to a processing chamber. The processing chamber is then flooded with an appropriate gas to cure the layered composite.

(21) Alternatively, the device for producing a part is integrated into a processing chamber, such that the layered composite can be cured directly therein.

(22) The layers of the layered composite exhibit sufficient reciprocal cohesion, such that the uncured layered composite can be removed from the deposition device without problems.

(23) However, the device can also have a building box in which the layers of the layered composite are produced such that the building box is filled up with the layers. The building box serves as a support means for the layered composite and reduces the danger of damage to the uncured layered composite, for instance during transport into a processing chamber for curing.