METHOD AND DEVICE FOR BUILDING UP A COMPONENT IN LAYERS FROM PHOTOPOLYMERIZABLE MATERIAL

Abstract

In a method of building up a component in layers from photopolymerizable material, in particular a resin with ceramic or metallic filler, in which component layers are successively formed one above the other by forming a layer of the highly viscous photopolymerizable material between a building platform or the component and a material carrier, which is cured in a location-selective manner to form the desired shape of the component layer, a cleaning step takes place after the component layer has been formed, in which uncured photopolymerizable material adhering to the component layer is removed by means of a cleaning unit after the component has been lifted.

Claims

1-18. (canceled)

19. A method of building up a component layer by layer from a photopolymerizable material, comprising successively forming component layers one on top of the other comprising the steps of: forming a material layer of the photopolymerizable material on a material carrier, lowering a building platform or the component at least partially built up on the building platform into the material layer, so that a layer of the photopolymerizable material is formed between the building platform or the component and the material carrier, curing the layer of the photopolymerizable material in a location-selective manner by irradiation through the material carrier to form the desired geometry of the component layer, lifting the component with the component layer, wherein the method further comprises carrying out a material removal step after the formation of the component layer, which comprises at least partially removing photopolymerizable material adhering to the component that is not or not fully cured after the component has been lifted by means of a material removal unit.

20. The method according to claim 19, wherein the material removal step comprises bringing the adhering photopolymerizable material into contact with an absorbent contacting element.

21. The method according to claim 19, wherein the material removal unit for the material removal step is brought between the lifted component and the material carrier.

22. The method according to claim 19, wherein the component is rotated to the side for the material removal step after having been lifted.

23. The method according to claim 20, wherein the contacting element is designed as a movable belt, the belt being moved after a material removal step in order to convey away a belt section with photopolymerizable material on it and provide a new belt section for a further material removal step.

24. The method according to claim 19, wherein the material removal step is carried out in at least two steps, with a partial amount of the adhering photopolymerizable material being removed in a first step and a remaining amount of the adhering photopolymerizable material being removed in a second step.

25. The method according to claim 20, comprising impregnating the absorbent contacting element with a solvent before it is brought into contact.

26. The method according to claim 20, wherein after the material removal step, applying particles to the component layer, the particles being transported with the contacting element to the component layer and being applied to the component layer by bringing the contacting element into contact with the component layer.

27. The method according claim 19, wherein, after the material removal step, subjecting the component layer to an optical inspection by means of an image recording device or a 3D scanner.

28. The method according to claim 19, wherein a first component layer is formed from a first photopolymerizable material and, after the material removal step to remove the first photopolymerizable material adhering to the first component layer, a second component layer is formed from a second photopolymerizable material, which is different from the first photopolymerizable material.

29. The method according to claim 19, wherein a component layer with a first geometry is formed from a first photopolymerizable material, wherein the first geometry leaves uncovered at least a sub-area of the component layer formed last, wherein first photopolymerizable material adhering to the component layer and to the at least one uncovered sub-area is removed by means of the material removal step and wherein a building step is then carried out with a second photopolymerizable material that differs from the first photopolymerizable material, the building step comprising curing material in the sub-area.

30. The method according to claim 19, wherein the material removal step comprises creating a fluid flow in the area of the adhering, uncured photopolymerizable material which carries the material along with it.

31. A device for building up a component layer by layer from a photopolymerizable material by means of a method according to claim 19, comprising a material carrier for photopolymerizable material, which is at least partially translucent, a building platform which is held at an adjustable height above the material carrier, an irradiation unit which can be controlled for the location-selective irradiation of a material layer formed between the underside of the building platform and the material carrier, whereby a component layer can be generated, a material removal unit for at least partial removal of uncured photopolymerizable material adhering to the component after it has been lifted.

32. The device according to claim 31, wherein the material removal unit comprises an absorbent contacting element, which is arranged to be brought into contact with the adhering photopolymerizable material.

33. The device according to claim 31, wherein the material removal unit is displaceably arranged to be brought between the lifted component and the material carrier for the material removal step.

34. The device according to claim 31, wherein the building platform is rotatably supported in order to rotate the component to the side for the material removal step after the lifting.

35. The device according to claim 33, characterized in that the contacting element is designed as a movable belt.

36. The device according to claim 34, characterized in that the contacting element is designed as a movable belt.

37. The device according to claim 32, wherein the material removal unit comprises an applicator for applying a solvent or particles to the contacting element.

Description

[0046] The invention is explained in more detail below with reference to exemplary embodiments shown schematically in the drawing. In the drawings

[0047] FIGS. 1 to 3 show a sectional view of a device for building up a component in layers in successive phases of the process sequence,

[0048] FIGS. 4 to 11 show the process of a material removal according to the invention,

[0049] FIGS. 12 to 16 show the process of a modified embodiment of the material removal according to the invention,

[0050] FIGS. 17 to 21 show the process of particle application according to the invention,

[0051] FIGS. 22 to 31 show the process of a modified embodiment of the material removal according to the invention,

[0052] FIG. 32 shows an embodiment of a belt-shaped material removal unit, and FIG. 33 shows an alternative embodiment of a material removal unit.

[0053] A method and a device for building up a component in layers from photopolymerizable material will first be described with reference to FIGS. 1 to 3, this being a device already known in principle from EP 2505341 A1. The device located in air or another gas atmosphere has a trough 1, the trough bottom of which forms a material carrier 2 which is transparent or translucent in at least a partial area 3. This partial area 3 of the material carrier covers at least the extent of the area that can be irradiated by the exposure unit 4, the exposure unit 4 being arranged below the material carrier 2. The exposure unit 4 has a light source (not shown) and a light modulator with which the intensity can be controlled by a control unit and set in a location-selective manner in order to generate an exposure field on the material carrier 2 with the geometry desired for the layer currently to be formed. Alternatively, a laser can also be used in the exposure unit, the light beam of which successively scans the exposure field with the desired intensity pattern via a movable mirror which is controlled by a control unit.

[0054] Opposite the exposure unit 4, a building platform 5 is provided above the material carrier 2, which is carried by a lifting mechanism (not shown) so that it is held in a height-adjustable manner above the material carrier 2 in the area above the exposure unit 4. The building platform 5 can also be transparent or translucent.

[0055] A bath of highly viscous photopolymerizable material 6 is located on the material carrier 2. The material level 7 of the bath is defined by a suitable element, such as a doctor blade, which applies the material uniformly to the material carrier 2 in a certain material layer thickness a. The trough 1 can, for example, be assigned a guide rail on which a carriage is guided displaceably in the direction of the double arrow 8. A drive ensures the back and forth movement of the carriage, which has a holder for a doctor blade. The holder has, for example, a guide and an adjusting device in order to adjust the doctor blade in the direction of the double arrow 9 in the vertical direction. The distance between the lower edge of the doctor blade and the material carrier 2 can thus be adjusted. The doctor blade is used when the building platform is in the lifted state as shown in FIG. 1, and serves to distribute the material 6 evenly while setting a predetermined layer thickness. The layer thickness of the material 6 resulting from the material distribution process is defined by the distance between the lower edge of the doctor blade and the material carrier 2.

[0056] The resulting material layer thickness a is greater than the component layer thickness b (FIG. 2). The following procedure is used to define a layer of photopolymerizable material. The building platform 5, on which component layers 10′, 10″ and 10′″ have already been formed, is lowered in a controlled manner by the lifting mechanism, as shown in FIG. 2, so that the underside of the lowermost component layer 10′″ first touches the surface of the material 6 having height a, then dips and approaches the material carrier 2 so far that exactly the desired component layer thickness b remains between the underside of the lowermost component layer 10′″ and the material carrier 2. During this immersion process, photopolymerizable material is displaced from the space between the underside of the lowermost component layer 10′″ and the material carrier 2. As soon as the component layer thickness b has been established, the location-selective exposure specific for this component layer takes place in order to cure the component layer 10″″ in the desired shape. After the component layer 10″″ has been formed, the building platform 5 is raised again by means of the lifting mechanism, which brings about the state shown in FIG. 3. The photopolymerizable material 6 is no longer present in the exposed area.

[0057] These steps are then repeated several times in order to obtain further component layers made of photopolymerizable material. The material no longer present in the exposed area is replaced by restoring the material level 7 or the material layer thickness a. The distance between the underside of the component layer 10″″ last formed and the material carrier 2 is set to the desired component layer thickness b and the photopolymerizable material is then cured in the desired manner in a location-selective manner.

[0058] When the building platform is raised, a quantity 13 of an uncured photopolymerizable material 6 remains adhering to the component, in particular to the component layer 10″″ built up last. According to the invention, the device therefore comprises a material removal unit 12, as shown in FIGS. 4 to 11. FIG. 4 shows the device before the component layer 10″″ is formed. The material removal unit 12 is positioned in its starting position next to the trough 1 and can be moved in the horizontal direction in the direction of the arrow 14 (FIG. 5). Adhering material 13 is now at least partially removed after the component layer 10″″ has been formed, in that the material removal unit 12 is initially brought between component 11 and trough 1 with the building platform 5 being lifted. Then the component layer 10″″ last produced and the material removal unit 12 are brought into contact by a relative movement in the direction of the arrow 15, so that the uncured material 13 adhering to the bottom and possibly the side surface of the lowermost component layer 10″″ is at least partially transferred to the material removal unit 12, so that the amount of material 13′ gets onto the material removal unit 12, as shown in FIG. 6. The amount of material 13′ is transferred to the material removal unit 12, for example, by the capillary action of an absorbent material in the material removal unit 12. A relative movement then takes place in order to separate the component from the material removal unit.

[0059] After this material removal step, a surface section of the material removal unit 12 is moved a little further in order to convey the removed amount of material away from the component layer 10″″ and to provide a new surface section of the material removal unit 12 for a further material removal step, as shown in FIG. 7. The material removal unit 12 is then brought back to its starting position (FIG. 8) so that a further component layer 10′″″ can be formed, to which in turn a quantity of material 13″ adheres (FIG. 9). The material removal unit 12 is moved between component 11 and trough 1 for the next material removal step and the amount of material 13′″ is transferred to the material removal unit 12 as described above (FIG. 10). Finally, the material removal unit 12 is brought into its starting position (FIG. 11) and the next component layer can be produced.

[0060] In the modified procedure according to FIGS. 12 to 16, the material removal unit 12 has an applicator 16 for a liquid, such as a solvent. Before the material removal unit 12 is moved between component 11 and trough 1, the liquid is applied to the surface of the material removal unit 12, so that a soaked layer 17 is formed (FIG. 13). The adhering amount of material 13 is then at least partially transferred from the component layer with the aid of the layer 17 (FIG. 15), so that the amount of material 13′ gests on the material removal unit 12.

[0061] In the embodiment according to FIGS. 17 to 21, the material removal unit 12 or a separate unit is used to apply particles 19 to the cleaned component layer 10′″″ before the next component layer is produced. As shown in FIG. 17, an applicator 18 is provided for this purpose, which applies particles 19 to the material removal unit 12 (FIG. 18). The applicator 16 preferably also applies a liquid, so that an impregnated layer 17 is formed. After the material removal unit 12 has been brought between the component 11 and the trough 1 (FIG. 20), by bringing the material removal unit 12 and the component layer 10″″ into contact perpendicularly, the particles 19 transfer to the component layer 10″″, such as shown in FIG. 21.

[0062] FIGS. 22 to 31 show an example of a method with which a component layer can be produced from two different photopolymerizable materials. For this purpose, a modified device is used which, compared to the preceding examples, has a second material trough 20 with a material carrier 21, in which a second material 22 is received.

[0063] First, a first component layer 10′″ is produced by dipping the component into the material 6 located in the trough 1 and curing the material 6 (FIG. 23). After the component 11 has been lifted (FIG. 24), a quantity of material 13 adheres again to the component layer 10″″ built up last, and as already described, the quantity of material 13′ is transferred to the material removal unit 12 (FIGS. 25 and 26). In FIG. 26 it can be seen that the component layer 10″″ leaves a partial area 23 of the component layer 10′″ uncovered. A layer of the second material 22 is now produced in this sub-area 23 by first moving the first trough 1 horizontally and instead arranging the second trough 20 between the component 11 and the exposure unit 4 (FIG. 27). The component 11 is then dipped into the second material 22 until the component layer 10 produced previously touches the material carrier 2, so that a material layer is formed in the sub-area 23 which is cured (FIG. 28). Since the adhering amount of material 13 of the first material 6 is previously at least partially transferred to the material removal unit 12 so that the material amount 13′ gets on the material removal unit 12, it is avoided that the material 6 mixes with the material 22 when it is immersed in the trough 20. Furthermore, it is avoided that the previously adhering amount of material 13 is also hardened by the last-mentioned layer building process and falsifies the geometry to be formed.

[0064] The partial layer 24 produced from the second material 22 can be seen in FIG. 29. The amount of material 13″ adhering to the last component layer is again at least partially transferred to the material removal unit 12 so that the material amount 13′″ gets on the material removal unit 12 (FIGS. 30 and 31).

[0065] FIG. 32 shows a preferred embodiment of the material removal unit 12. The material removal unit 12 comprises a displaceable belt 25 which is unrolled from a supply roll 26 and rolled onto the receiver roll 27. In between, the movable belt 25 is guided around several deflection and pressure rollers, with a section of the belt 25 located between the rollers 28 and 29 forming the contact section which is brought into contact with the component layer in order to at least partially transfer the adhering amount of material 13 onto the material removal unit 12, so that the amount of material 13′ gets on the material removal unit 12. The movable belt 25 can consist of an absorbent material, in particular based on cellulose.

[0066] FIG. 33 shows an alternative embodiment of the material removal unit 12, with which the adhering amount of material 13 is at least partially removed or sucked off pneumatically. For this purpose, the material removal unit 12 comprises a first channel 30 for a gas which, using the Venturi effect, generates a negative pressure at the confluence of the channel 32. Another channel 31 opens out on the surface of the material removal unit 12 and generates a gas jet directed against the adhering amount of material 13. In order to prevent the adhering amount of material 13 from being pressed into the component 11, an overpressure is also generated on the underside of the component by generating a gas pressure via bores 33 (or other cavities) formed in the component 11 and the building platform 5, which leads adhering amount of material 13 in the direction of the channel 32.