Method for producing a three-dimensional shaped object by means of layer-by-layer material application

Abstract

In a method for producing a three-dimensional mold and a three-dimensional shaped object (1) by means of layer-by-layer material application, geometry data for the shaped object (1), a support part (2) having a base surface (3) for holding the three-dimensional shaped object (1), and a first and a second material (4, 5) that can be solidified are made available. In the solidified state, the second material (5) has a greater strength than the solidified first material (4). The solidified first material (4) can dissolve in the solvent. To form a negative-shape layer (12), material portions of the flowable first material (4) are applied to the base surface (3) and/or to a solidified material layer of the three-dimensional shaped object (1) situated on this surface, in accordance with the geometry data, in such a manner that the negative-shape layer (12) has at least one cavity (13) that has a negative shape of a material layer of the shaped object (1) to be produced. The negative-shape layer (12) is solidified. To form a shaped-object layer (16), the cavity (13) is filled with the second material (5), and afterward the second material (5) is solidified. Regions of the solidified negative-shape layer (12) and/or shaped-object layer (16) that project beyond a plane arranged at a predetermined distance from the base surface (3) are removed by means of machining material removal. The steps mentioned above are repeated at least once. The negative-shape layers (12) are brought into contact with the solvent in such a manner that the solidified first material (4) dissolves in a solvent.

Claims

1. A method for producing a three-dimensional shaped object by layer material application, the method comprising: a) providing geometry data for the three-dimensional shaped object, a support part having a base surface for holding the three-dimensional shaped object, a liquid or flowable first material that can be solidified, a liquid, flowable, paste-like or powder-form second material that can be solidified, and a solvent, wherein the second material, in a solidified state, has a greater strength than the first material in a solidified state, and the first material in the solidified state can be dissolved in the solvent; b) forming a negative-shape layer, by applying material portions of the flowable first material to the base surface and/or to a solidified material layer of the three-dimensional shaped object situated on the base surface, in accordance with the geometry data, wherein the negative-shape layer has at least one cavity on a surface facing away from the base surface, which cavity has a negative shape of a material layer of the three-dimensional shaped object to be produced; c) solidifying the negative-shape layer to form a mold; d) filling the mold with the second material to form a shaped-object layer, wherein the negative shape is transferred to the shaped-object layer as a positive shape; e) solidifying the second material filled into the mold; f) removing regions of the solidified negative-shape layer and/or of a solidified shaped-object layer projecting beyond a plane arranged at a predetermined distance from the base surface by machining material removal; g) repeating steps a) to f) at least once; and h) bringing the negative-shape layers into contact with the solvent in such a manner that the solidified first material dissolves in the solvent.

2. The method according to claim 1, wherein the material portions of the first material are applied to the base surface and/or to the solidified negative-shape layer situated on the base surface and/or to a solidified shaped-object layer, the first material is a material that can be solidified by applying energy, and solidifying the negative-shape layer comprises applying energy to the negative-shape layer.

3. The method according to claim 2, wherein a gas pressure is applied to the second material, and the second material put under pressure is passed to at least one jet by way of at least one valve, an exit opening of the at least one jet is positioned along the base surface relative to the support part, the at least one valve is controlled as a function of the geometry data made available for the three-dimensional shaped object to be produced and as a function of a relative position between the at least one jet and the support part, the material flow is released when the exit opening is positioned at the at least one cavity, and the material flow is blocked when the exit opening is not positioned at the at least one cavity.

4. The method according to claim 1, wherein a viscosity of the second material in a non-solidified state is greater than the viscosity of the first material in a non-solidified state and/or the flowable first material and the flowable, paste-like or powder-form second material have a solids proportion and the solids proportion of the second material in the non-solidified state is greater than the solids proportion of the first material in-its the non-solidified state.

5. The method according to claim 4, wherein the viscosity of the second material in the non-solidified state is at least 10 times greater than the viscosity of the first material in the non-solidified state and/or the solids proportion of the second material in the non-solidified state is at least 10 times greater than the solids proportion of the first material in the non-solidified state.

6. The method according to claim 1, wherein the first material has a working viscosity suitable for jetting, which is less than 1000 mPa.Math.s, and is applied to the base surface and/or to the solidified material layer of the three-dimensional shaped object situated on the base surface, in the form of droplets of liquid, at a resolution of at least 360 dpi.

7. The method according to claim 1, wherein the second material is applied to the negative-shape layer by a selective coating method, as a function of the geometry data, at least one material portion of the flowable, paste-like or powder-form second material is dispensed into the at least one cavity, and at least one location of the negative-shape layer situated outside of the at least one cavity is not brought into contact with the second material.

8. The method according to claim 7, wherein the second material has a greater viscosity and/or a greater solids proportion than the first material, both the first material and the second material are applied to the base surface and/or to a solidified negative-shape layer situated on the base surface and/or a shaped-object layer by an inkjet printing method, in the inkjet printing method, the first material is ejected from at least one first jet and the second material is ejected from at least one second jet, and an exit opening of the at least one second jet has a greater cross-section than an exit opening of the at least one first jet and/or a higher working pressure applied to the at least one second jet than is applied to the at least one first jet.

9. The method according to claim 8, wherein the exit opening of the at least one second jet is moved along a continuous line that runs within the at least one cavity, relative to the support part and the liquid, flowable or paste-like second material is continuously dispensed along this line, from the exit opening into the at least one cavity.

10. The method according to claim 8, wherein a diameter of the exit opening of the at least one second jet is greater than a diameter of the exit opening of the at least one first jet.

11. The method according to claim 7, wherein a support film is provided, on which the second material is arranged, the second material has a greater viscosity than the first material and/or contains a greater solids proportion than the first material, the support film is positioned at the at least one cavity during filling of_the at least one cavity with the second material the second material situated on the support film faces the at least one cavity, and an energy beam for which the support film is permeable is directed at the support film in such a manner that the second material is heated and liquefied on a side of the support film facing the at least one cavity and is dispensed into the at least one cavity.

12. The method according to claim 1, wherein the second material is a composite comprising a fluid and at least one additive, the fluid has a viscosity of at least 50 mPa.Math.s at room temperature, and the additive contains solid particles that are arranged in the fluid.

13. The method according to claim 1, wherein the second material is filled into the at least one cavity using a flexographic printing method, a gravure printing method, an offset printing method, a screen printing method, a laser transfer method, a micro-metering method, and/or using a doctor blade or a chamber doctor blade.

14. The method according to claim 1, wherein the second material is a thermoplastic that liquefies by being heated, is filled into the at least one cavity after being liquefied, and is solidified by cooling.

15. The method according to claim 1, wherein an uppermost solidified negative-shape layer and/or an uppermost solidified shaped-object layer is/are cleaned to remove chips that occur during machining material removal.

16. The method according to claim 1, wherein the support part having the base surface is rotated about an axis of rotation during material application and, optionally, during solidification of the first and/or second materials.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, exemplary embodiments of the invention are explained in greater detail, using the drawings. These show:

(2) FIG. 1 a preferred apparatus in a polar embodiment, for producing a three-dimensional shaped object by means of layer-by-layer material application, wherein the apparatus has different dispensing devices for dispensing different liquid materials that can be solidified,

(3) FIG. 2 a side view of an apparatus for producing a three-dimensional shaped object, wherein the apparatus has a first dispensing device, which has jets for layer-by-layer application of a liquid first material and a second material application station configured as a flexographic printing apparatus or a gravure printing apparatus for application of a liquid second material,

(4) FIG. 3A to 3F a cross-section through a shaped object during different method steps of its production,

(5) FIGS. 4 and 4A a side view of a thickness milling tool during milling removal of a material layer,

(6) FIG. 5 a cross-section through a first exemplary embodiment of a shaped object after application of all the material layers,

(7) FIG. 6 a schematic representation of the solidified material layers of the shaped object consisting of the first and second material, wherein the layers are shown in transparent form,

(8) FIG. 7 a three-dimensional view of a layer stack consisting of the material layers of the first and second material,

(9) FIG. 8 a three-dimensional view of the shaped object after removal of the material layer of the first material, using a solvent,

(10) FIG. 9 a cross-section through a second exemplary embodiment of a shaped object after application of all the material layers,

(11) FIG. 10 a cross-section through the second exemplary embodiment of the shaped object after removal of the material layers of the first material,

(12) FIG. 11 a side view of an apparatus similar to FIG. 2, wherein, however, a rotation screen printing apparatus is provided in place of the flexographic printing apparatus,

(13) FIG. 12 a side view of an apparatus similar to FIG. 2, wherein, however, a chamber doctor blade coating apparatus is provided in place of the flexographic printing apparatus,

(14) FIG. 13 a cylindrical coating roll,

(15) FIG. 14 a coating roll in the form of a truncated cone,

(16) FIG. 15 a side view of an apparatus similar to FIG. 2, wherein, however, an inkjet printing apparatus for higher viscosities is provided in place of the flexographic printing apparatus,

(17) FIG. 16 a side view of an apparatus similar to FIG. 2, wherein, however, a hot-melt apparatus or a micro-metering/micro-coating apparatus is provided in place of the flexographic printing apparatus,

(18) FIG. 17 an enlarged detail from FIG. 16, which shows a jet during filling of a cavity with the second material,

(19) FIG. 18 a schematic representation of a print head module for applying the second material,

(20) FIG. 19 a cavity that was filled with the second material,

(21) FIG. 20 a micro-metering unit having a jet that has a circular exit opening, and

(22) FIG. 21 a micro-metering unit having a jet that has a rectangular exit opening.

DESCRIPTION OF THE INVENTION

(23) In a method for producing a three-dimensional mold and a three-dimensional shaped object 1 by means of layer-by-layer material application, geometry data for the shaped object 1 are made available by a control unit that communicates with a computer on which software is running. Furthermore, a plate-shaped support part 2 having a base surface 3 arranged in a horizontal plane, for holding the shaped object 1, is made available. As can be seen in FIG. 1, the base surface 3 essentially has the shape of a circular ring disk. However, other embodiments are also conceivable, in which the base surface 4 particularly can have the shape of a full circular disk or can be configured to be rectangular.

(24) Furthermore, in the method a liquid first material 4 that can be solidified, a liquid second material 5 that can be solidified, different from the first, and water as a solvent for the solidified first material 4 are made available. The solidified second material 5 cannot dissolve in the solvent. The second material 5 is selected in such a manner that it has a greater strength in the solidified state than the solidified first material 4. For this reason, the second material 5 has a greater viscosity than the first material 4. In this exemplary embodiment, the first material 4 is a polymer that contains a photo-initiator and can be cross-linked by means of irradiation with ultraviolet radiation.

(25) The liquid first material 4 is arranged in a first reservoir 6, and the liquid second material 5 is arranged in a second reservoir 7. The first reservoir 6 is connected with a first dispensing device 8 for the first material 4 by way of a line. As can be seen in FIG. 2, the first reservoir 5 is configured as an essentially closed container, and the second reservoir 7 is configured as a vat.

(26) The first dispensing device 8 has a first inkjet printing head having a plurality of jets arranged in a row, which are not shown in any detail in the drawing, and are set up for dispensing material portions of the first material 4 onto the base surface 3 or onto a solidified material layer of the first and/or second material 4, 5 situated on this surface. The row of jets is arranged parallel to the plane of the base surface 4 and extends transverse to the circumference direction of the base surface 3, preferably essentially radially towards its center.

(27) The support part 2 and the first dispensing device 8 can be rotated relative to one another using a first positioning device 9, in and opposite to the direction of the arrow 10, and can be displaced parallel to the axis of rotation 11. During this process, points that lie in the base surface 3 and are at a distance from the axis of rotation 11 move along a path curve shaped like a helical line or screw line.

(28) The first dispensing device 8 and the first positioning device 9 are connected with a control device, not shown in any detail in the drawing, which has a data memory for storage of the geometry data of the shaped object 1 to be produced. Dispensing of the material portions of the first material 4 as well as the first positioning device 9 can be controlled by means of the control device, as a function of the geometry data, in such a manner that negative-shape layers 12 consisting of the flowable first material 4 can be applied to the base surface or to a solidified material layer of the first and/or second material 4, 5 that was previously applied to this surface (FIG. 3A). In this regard, the negative-shape layers 12 each have at least one cavity 13, which has a negative shape of a material layer of the shaped object 1 to be produced. The cavities 13 extend, in each instance, over the entire layer thickness of the negative-shape layer 12 in question, all the way to the base surface 3 or to the solidified material layer situated under the negative-shape layer 12.

(29) A first solidification device 14 is arranged behind the first dispensing device 8 in the direction of the arrow 10, by means of which device the liquid first material 4 applied to the base surface 3 or to a solidified material layer situated on this surface can be solidified. For this purpose, the first solidification device 14 has a first UV radiation source, not shown in any detail in the drawing, by means of which the ultraviolet radiation can be dispensed to the material layer of the first material to be solidified, in such a manner that a photo-cross-linking agent contained in the first material is activated and the polymers contained in the first material 4 are cross-linked.

(30) A second dispensing device 15 is arranged behind the first solidification device 14 in the direction of the arrow 10, by means of which device the cavity/cavities 13 of the corresponding negative-shape layer 12 that was previously solidified are filled with the second material 5, so as to form a shaped-object layer 16 (FIG. 3B). In the exemplary embodiment shown in FIG. 2, the second dispensing device 15 is configured as a flexographic printing apparatus.

(31) This apparatus has a transfer body 17 configured as a flexographic printing roll, and a coating device 18 that stands in contact with the second reservoir 7, by means of which device the at least one surface region of the transfer body 17 can be coated with a layer 19 of the second material 5. Using a second positioning device, the conical transfer body 17 can be rotated about an imaginary axis of rotation, in such a manner that the layer 19 of the second material 5 situated on the mantle surface of the transfer body 17 comes into contact with the bottom and the inner wall of the cavity/cavities 13, in such a manner that the flowable second material 5 is filled into the cavity/cavities and then forms the shaped-object layer 16. This layer has the positive shape of a layer of the shaped object 1 to be produced, which shape is inverse to the negative shape of the layer 12.

(32) Afterward, the shaped-object layer 16 obtained in this manner is solidified using a second solidification device 21. As can be seen in FIG. 1, the second solidification device 21 is arranged behind the second dispensing device 14 in the direction of the arrow 10. The second solidification device 21 contains a second UV radiation source, by means of which ultraviolet radiation can be dispensed onto the shaped-object layer 15, so as to solidify the second material by means of cross-linking the polymers contained in it.

(33) Afterward, in a further method step, regions of the solidified negative-shape layer 12 and/or of the solidified shaped-object layer 16 and/or of the solidified second material 5 that is arranged on the negative-shape layer are removed by means of a thickness milling tool 22 (FIG. 3C, 4, 4A). During this process, regions of the solidified first and/or second material 4, 5 that project beyond a plane arranged at a predetermined distance from the base surface, parallel to it, are completely removed by means of machining material removal, and subsequently vacuumed away by means of a suction nozzle 23. If necessary, a surface cleaning device 20 can be arranged behind the suction nozzle 23.

(34) Now, in a corresponding manner, a further negative-shape layer 12 (FIG. 3D) and a further shaped-object layer 16 are applied to the surface of the solidified negative-shape layer 12 and the shaped-object layer 16 (FIG. 3E, 3F). These steps are repeated until all the shaped-object layers 16 of the shaped object to be produced have been produced (FIG. 5 to 8).

(35) In a further method step, the negative-shape layers 12 are brought into contact with the solvent in such a manner that the solidified first material 4 completely dissolves in the solvent. This result can be achieved, for example, in that the layer stack consisting of the negative-shape layers 12 and the shaped-object layers 16 is immersed in the solvent for a predetermined period of time. Afterward, the finished shaped object (FIG. 8) is removed from the solvent and dried.

(36) As can be seen in FIGS. 9 and 10, it is also possible to produce shaped objects having overhangs 25 and cavities 26, using the method according to the invention.

(37) The second material 5 can also be filled into the cavity/cavities 13 using a screen-printing method. As can be seen in FIG. 11, in this process the transfer body 18 is configured as a rotation screen-printing roll. This roll has a perforated, screen-like mantle surface. The second reservoir 6 is arranged in the inner cavity of the rotation screen-printing roll.

(38) The perforated holes provided in the mantle surface are coordinated with the viscosity of the second material 5, with regard to their dimensions, in such a manner that the second material 5 can be pressed through the perforated holes by means of a doctor blade 24 that lies against the inner mantle surface of the cylinder wall of the rotation screen-printing roll in line shape. Outside of the region of effect of the doctor blade 24, the second material 5 does not pass through the perforated holes. A cleaning apparatus placed behind the dispensing location removes the material not taken off from the rotation screen-printing roll, and passes it back into the circuit for re-use. For the remainder, the apparatus shown in FIG. 11 corresponds to that shown in FIG. 2, so the description of FIG. 2 applies analogously to FIG. 11.

(39) The second material 5 can also be filled into the cavity/cavities 13 using the chamber doctor blade method. As can be seen in FIG. 12, in this regard the transfer body 18 is structured as a raster roll, on the outer mantle surface of which a chamber doctor blade 32 is arranged. The raster roll has a correspondingly engraved mantle surface, prepared to hold the material. For the remainder, the apparatus shown in FIG. 12 corresponds to that shown in FIG. 2, so that the description of FIG. 2 applies analogously to FIG. 12.

(40) While the roll of the coating device 18 has a cylindrical shape in the case of the Cartesian method (FIG. 13), in the case of the polar method the roll has a conical shape (FIG. 14).

(41) The second material 5 can also be filled into the cavity/cavities 13 using the inkjet printing method (FIG. 15). For this purpose, the second dispensing device 15 has a second inkjet printing head having a plurality of jets arranged in a row, which are set up for dispensing material portions of the second material 5 onto the base surface 3 or onto a solidified material layer of the first and/or second material 4, 5 situated on this surface. The row of jets is arranged parallel to the plane of the base surface 4 and extends transverse to the circumference direction of the base surface 3, preferably essentially radially towards its center. Since the second material 5 has a greater viscosity than the first material 4, the jets of the second inkjet printing head have a greater cross-section than those of the first inkjet printing head. Instead of working with a greater jet cross-section or in addition to that, it is also possible to work with a higher jet pressure than that of the first jets in the case of the jets of the second inkjet printing head. Positioning of the support part 2 relative to the inkjet printing head takes place in accordance with FIG. 1, using a positioning device. Ejection of the second material 5 is controlled as a function of the relative position between the inkjet printing head and the support part 2 and as a function of the geometry data made available for the shaped object 1 to be produced.

(42) In the case of the exemplary embodiment shown in FIG. 16, the second material 5 is filled into the cavity/cavities 13 using the jet method or hot-melt method. In the case of the jet method, a high-viscosity second material 5 is conveyed through a jet exit at room temperature or in a state in which it is heated as compared with room temperature, by means of gas pressure. In the case of the hot-melt method, the second material 5 is a thermoplastic plastic that is solid at room temperature and can be liquefied by means of heating it. During the printing process, the second material is heated in such a manner that it becomes liquid, and then it is dispensed onto the base surface 3 or onto a solidified material layer of the first and/or second material 4, 5 situated on this surface, by means of a metering pump, a conveying screw or gas pressure, through a jet 27 directed at the cavity 13 to be filled (FIG. 17). Positioning of the support part 2 relative to the jet 27 takes place in accordance with FIG. 1, using a positioning device 9. Ejecting the second material 5 from the jet 27 is controlled as a function of the relative position between the jet 27 and the support part 2 and as a function of the geometry data made available for the shaped object 1 to be produced. After the second material has been filled into the cavity/cavities 13, it is solidified by means of cooling.

(43) Furthermore, the possibility exists of filling the second material 5 into the cavity/cavities 13 by means of a micro-metering method. As can be seen in FIG. 18, in this regard the second reservoir 7 is connected with a gas pressure source 28, which can be a compressed-air source, for example, so as to put pressure on the second material 5. The reservoir 7 is connected with a jet 27 for dispensing material, by way of lines 29 in which a valve 30 that can be adjusted between an open position and a closed position, in each instance, is arranged. The exit opening of the jet 27 is arranged with its exit opening at a slight distance from the base surface 3 [sic-duplication of exit opening in the German], and then positioned in such a manner along the base surface 3, relative to the support part 2. The individual valves 30 are controlled, in each instance, as a function of the geometry data made available for the shaped object 1 to be produced, and as a function of the relative position between the jet 27 and the support part 2, in such a manner that the material flow of the second material 5 is released when the exit opening of the jet 27 is positioned at the cavity 13. The material flow is blocked when the exit opening of the jet 27 is not positioned at the cavity 13.

(44) As can be seen in FIG. 18, multiple micro-metering units 31 can be provided, the valve 30 of which is connected with the second reservoir 7 with its inlet, in each instance, by way of a line 29. Each micro-metering unit 31 has a jet 27, in each instance, which is connected with the outlet of the valve 30 in question. The jets 27 are arranged in matrix shape, in multiple rows and/or multiple columns. The valves 30 are controlled in such a manner that the second material 5 is applied to the cavity 13 in planar manner (FIG. 19). The jet 27 can have a round (FIG. 20) or a polygonal, preferably a rectangular (FIG. 21) exit opening.