SYSTEM FOR ADDITIVE MANUFACTURING OF AN OBJECT

Abstract

The invention provides a system (100) for additive manufacturing of an object, with a plasticizer (200) comprising a feeder (210) for feeding a material, a horizontal barrel (250) for liquefying the fed material, a conditioner (220) for heating the barrel (250), a nozzle (230) for outputting the liquid material in a continuous flow, and a conveyor (240) for transporting the material through the plasticizer (200). The nozzle (230) comprises a vertical main body (232), and, at a bottom end, a head (233) having the output opening (231). The main body (232) comprises an expansion space (260) for accommodating the liquid material. The first conditioner (220) is arranged for heating the nozzle (230). The system (100) is configured so that the output opening (231) is positioned at a fixed position during additive manufacturing. The system (100) comprises a printing bed (300) for applying the liquid material thereon, and a first support device (400) for moving the printing bed (300) according to 6 degrees of freedom.

Claims

1. A system for additive manufacturing of an object, wherein the system comprises: at least one plasticizer, wherein the at least one plasticizer comprises a feeder for feeding a material for additive manufacturing of the object, a first conditioner at least arranged for heating the at least one plasticizer for liquefying the fed material in such a way as to allow additive manufacturing of the object using the liquid material, a nozzle having an output opening for outputting the liquid material in a continuous flow, and a conveyor for transporting the fed material and the liquid material through the at least one plasticizer (200) from the feeder to the nozzle, wherein the system is configured in such a way that the output opening of the nozzle, at least during additive manufacturing of the object, is located in a predetermined fixed position in the system; a printing bed arranged for applying the liquid material from the at least one plasticizer thereon for additive manufacturing of the object; and a first support device for supporting the printing bed and moving the printing bed according to 6 degrees of freedom, wherein the at least one plasticizer comprises a barrel for liquefying the fed material therein, wherein the barrel is connected to the feeder, wherein the first conditioner is arranged for heating the barrel for liquefying the fed material, wherein the barrel extends along a horizontal direction, wherein the conveyor is arranged for transporting the fed material and the liquid material through the barrel along the horizontal direction, wherein the nozzle comprises a main body that is connected to the barrel and that extends downward along a vertical direction, wherein the nozzle, at a bottom end of the main body, is provided with a head having the output opening, wherein the main body comprises an expansion space for accommodating the liquid material, wherein the first conditioner is arranged for heating the nozzle independently of the barrel, for maintaining the liquid material in a liquid state.

2. The system according to claim 1, wherein the volume of the expansion space is adjustable.

3. The system according to claim 1, wherein a wall of the expansion space is provided with at least one slidable wall section for adjusting the volume of the expansion space, wherein the at least one slidable wall section comprises a bimetal.

4. (canceled)

5. The system according to claim 2, wherein the at least one plasticizer comprises a controller for controlling the adjustment of the volume of the expansion space, wherein the controller comprises at least one pressure sensor in at least one of the barrel, the expansion space and the head of the nozzle for measuring the pressure in the liquid material, and wherein the controller is configured to adjust the volume of the expansion space, based on the pressure measured by the at least one pressure sensor, in such a way that a predetermined pressure in the liquid material is established at the output opening of the nozzle.

6. The system according to claim 1, wherein the expansion space extends through the main body of the nozzle along the vertical direction as a conduit for the liquid material from a passage duct for the liquid material from the barrel to an output duct for the liquid material in the head of the nozzle (230), wherein the expansion space has a larger diameter than the passage duct and the output duct.

7. (canceled)

8. The system according to claim 1, wherein the first conditioner is arranged for heating the main body and the head of the nozzle independently of each other.

9. The system according to claim 1, wherein the feeder is arranged for feeding a plastic as the material.

10. (canceled)

11. The system according to claim 9, wherein the feeder is arranged for feeding the plastic as at least one of a granulated material, a regranulated material, a ground material and/or a densified material.

12. The system according to claim 11, wherein the feeder is provided with an agitator to agitate the fed plastic.

13. The system according to claim 1, wherein the conveyor is also arranged for transporting the fed material and the liquid material through the at least one plasticizer from the nozzle to the feeder.

14. The system according to claim 1, wherein the nozzle is provided with a closing element for opening and closing the output opening.

15. The system according to claim 1, wherein the conveyor comprises at least one screw for transporting the fed material and the liquid material through the barrel, and wherein the at least one screw comprises a central shaft that is provided with protruding elements.

16. (canceled)

17. The system according to claim 15, wherein the at least one screw is divided into a plurality of screw zones, wherein each screw zone is adapted for a different phase in the process of transporting and liquefying the fed material.

18-19. (canceled)

20. The system according to claim 15, wherein the at least one screw is driven by at least one motor.

21. (canceled)

22. The system according to claim 1, wherein the first support device is arranged for simultaneously moving the printing bed according to at least 3 degrees of freedom.

23. The system according to claim 1, wherein the first support device comprises a robotic arm for supporting and moving the printing bed.

24. The system according to claim 1, wherein the system comprises at least one second support device for supporting the at least one plasticizer, wherein the at least one second support device is arranged for tilting the at least one plasticizer so that the output opening remains positioned at the predetermined fixed position in the system.

25. The system according to claim 1, wherein the nozzle of the at least one plasticizer is tiltable relative to the at least one plasticizer.

26. The system according to claim 1, wherein the system further comprises a preparation device that is arranged for making the material to be fed to the at least one plasticizer suitable for use in the at least one plasticizer.

27. Use of the system according to claim 1 for additive manufacturing of an object.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0116] The invention will hereafter be elucidated in further detail by means of the following description and the appended figures.

[0117] FIG. 1 shows a perspective view of a system for additive manufacturing of an object according to a first embodiment of the present invention.

[0118] FIG. 2 shows a side view of the system of FIG. 1.

[0119] FIG. 3 shows a perspective view of a system for additive manufacturing of an object according to a second embodiment of the present invention.

[0120] FIG. 4 shows a side view of the system of FIG. 3.

[0121] FIG. 5 shows a top view of the system of FIG. 3.

[0122] FIG. 6 shows a perspective view of a plasticizer of a system for additive manufacturing of an object according to an embodiment of the present invention.

[0123] FIG. 7 shows a cross section through the plasticizer of FIG. 6.

[0124] FIG. 8 shows a cross section through the nozzle of the FIG. 6.

[0125] FIGS. 9A and 9B show a cross-sectional schematic depiction of a head of a nozzle according to an embodiment of the present invention while smearing expelled liquid material.

[0126] FIG. 10 shows a screw of a plasticizer of a system for additive manufacturing of an object according to an embodiment of the present invention.

MODES FOR CARRYING OUT THE INVENTION

[0127] The present invention will hereafter be described with respect to particular embodiments and with reference to certain drawings, but the invention is not limited thereto and is defined only by the claims. The drawings shown here are merely schematic depictions and are non-limiting. In the drawings, the dimensions of certain parts may be exaggerated, meaning that the parts in question are not drawn to scale, for illustrative purposes only. The dimensions and the relative dimensions do not necessarily correspond to the actual reductions to practice of the invention.

[0128] Furthermore, terms such as “first”, “second”, “third” and the like are used in the description and in the claims for distinguishing between similar elements, and not necessarily for describing a sequential or chronological order. The terms in question are interchangeable under the appropriate circumstances and the embodiments of the invention can operate in other sequences than described or illustrated here.

[0129] Moreover, terms such as “top”, “bottom”, “over”, “under” and the like are used in the description and the claims for descriptive purposes and not necessarily for indicating relative positions. The terms so used are interchangeable under the appropriate circumstances, and the embodiments of the invention can operate in other orientations than those described or illustrated herein.

[0130] The term “comprising” and derivative terms, as used in the claims, should not be interpreted as being restricted to the means listed respectively thereafter; the term does not exclude other elements or steps. It should be interpreted as specifying the stated features, integers, steps or components as referred to, without, however, precluding the presence or addition of one or more additional features, integers, steps or components, or groups thereof. Thus, the scope of an expression such as “a device comprising means A and B” is not limited to devices consisting only of components A and B. What is meant, on the contrary, is that with respect to the present invention, the only relevant components of the device are A and B.

[0131] FIGS. 1 and 2 show a system 100 according to a first embodiment of the present invention for additive manufacturing of an object, in a perspective view and a side view, respectively. FIGS. 3-5 show a system 100 according to a second embodiment of the present invention for additive manufacturing of an object, in a perspective view, a side view and a top view, respectively.

[0132] The systems 100 according to both embodiments comprise three plasticizers 200 that are each arranged for outputting a different type of molten plastic material for use during additive manufacturing of the object. This offers the advantage that objects consisting of different plastic materials or different objects from different plastic materials can be manufactured using the same system 100. It should be noted that although in the embodiments discussed, plastic material is used as a material for additive manufacturing of the object, in alternative embodiments, any other materials known to the person skilled in the art that are suitable for the additive manufacturing of objects may also be used, such as for example a fiber wax, a mineral or a gel. It should also be noted that in alternative embodiments, the system 100 may be provided with a different number of plasticizers 200.

[0133] Each plasticizer 200 is housed in a different station 150 of the system 100. Preferably, the plasticizers 200 are housed interchangeably in the stations 150, so that the system 100 is adjustable for the use of other plastic materials for additive manufacturing of objects. If so desired, finishers (not shown) can also be housed in the stations 150, which are arranged for finishing an object that was additively manufactured using the system 100. The finishing of the object may for example entail removing excess plastic material, cleaning or coating the object.

[0134] The plasticizers 100 are housed in a first compartment 110 of the system 100. The first compartment 110 is preferably reserved for housing parts of the system 100 that generate heat, which heat could have a negative impact on the process of additive manufacturing of the object, which mainly takes place in a dedicated second compartment 120 of the system 100. For the same reason, the first compartment 110 is preferably located above the second compartment 120, so that the heat generated by the parts of the system 100 housed in the first compartment 110 does not pass through the second compartment 120 as it rises.

[0135] To provide the first compartment 110 and the second compartment 120, containers 160 can be used, as in the embodiments shown, but this can also be accomplished in any other suitable way known to the person skilled in the art. Containers 160 offer the advantage that they provide simple building blocks for the modular construction of the first compartment 110, the second compartment 120 and any additional compartments of the system 100.

[0136] The plasticizer 200, as shown in more detail in the FIGS. 6 and 7, comprises a feeder 210 that is arranged for feeding a plastic in a solid state in the plasticizer 200. In the embodiment shown, a hopper 210 is used for the feeder 210, but in other embodiments, other suitable feeders known to the person skilled in the art may also be used. The fed plastic material is preferably a thermoplastic material. Preferably, the plastic is also supplied in the form of a granulated material, a regranulated material, a ground material, a densified material or a combination thereof.

[0137] The feeder 210 is provided with an agitator 215 for agitating fed plastic material, in the form of a granulated material, a regranulated material, a ground material, a densified material or the like, for example by making it vibrate. This is because, when using a fed plastic material in such a form, “bridges” may form in the fed plastic material at the level of a feed opening 211 to the further parts of the plasticizer 200, which “bridges” form an obstruction to a smooth feeding of the plastic. By agitating the fed plastic material, the agitator 215 ensures that the “bridges” are broken, so that the plastic feed can again run smoothly. The agitator 215 may be a vibrating actuator for making the hopper 210 itself vibrate, and with it the fed plastic material present in the hopper. However, other embodiments of the agitator are also possible, such as for example a device for creating air currents in the fed plastic material.

[0138] The plastic is fed from the feeder 210 through the feed opening 211 to a barrel 250 of the plasticizer 200, which barrel 250 is arranged for melting the fed plastic material therein. The molten plastic material is then further transported by a conveyor 240 of the plasticizer 200 to a nozzle 230 of the plasticizer 200. Finally, the molten plastic material is ejected from the plasticizer 200 through an output opening 231 of the nozzle 230, to be used for additive manufacturing of an object. The diameter d4 of the output opening 231 is preferably in the range of 2.5-10 mm, in order to output a sufficient amount of the molten plastic material for additive manufacturing of large objects.

[0139] In order to melt the fed plastic material, the plasticizer 200 is provided with a first conditioner 220 around the barrel 250. The first conditioner 220 is arranged for heating the barrel 250 and the plastic material present therein, and thus to melt the fed plastic material. The barrel 250 extends along a horizontal direction H, so that the excess heat generated by the first conditioner 220 can quickly rise out of the plasticizer 200 without impacting or disrupting any other processes in the barrel 250 and the plasticizer 200. In the embodiment shown, the first conditioner 220 is also arranged for heating the nozzle 230, so as to ensure that the molten plastic material remains in a liquid state while passing through the nozzle 230, and for maintaining the molten plastic material in the nozzle 230 under controlled conditions, and to thus allow an even flow of the molten plastic material to be expelled at the output opening 231 of the nozzle 230, preferably at a predetermined pressure, preferably at a predetermined pressure in the range of 20-200 bar. Here, the heating of the nozzle 230 and the heating of the barrel 250 by the first conditioner 220 may be carried out independently of each other, so that the heating of the barrel 250 can be specifically attuned to melting the fed plastic material, and so that the heating of the nozzle 230 can be specifically attuned to keeping the molten plastic material in a liquid state and under controlled conditions.

[0140] In the barrel 250, different zones 251, 252, 253 can be distinguished. In a first zone 251, the plastic material fed from the feeder 210, still in solid state, is pulled into the barrel 250. In a second zone 252, the retracted plastic material is then melted by means of the first conditioner 220. Thus, in the second zone 252, the transition is made from the plastic in a solid state to the molten plastic material in a liquid state. In a third zone 253, the molten plastic material is then further pumped to the nozzle 230.

[0141] The fed plastic material and the molten plastic material is transported through the barrel 250 along the horizontal direction H by means of the conveyor 240. In the embodiment shown, the conveyor 240 comprises a screw 241 driven by a motor 249. The screw 241 extends in its length direction through the entire barrel in the horizontal direction H. The outer diameter d1 of the screw 241 is substantially equal to the inner diameter of the barrel 250, causing the plastic material fed into the barrel by means of the thread 244 of the screw 241 to be transported through the barrel 250 when rotating the screw 241 by means of the motor 249. The outer diameter d1 of the screw 241 is preferably in the range of 15-25 mm. Such dimensions of the screw 241 and, accordingly, of the barrel 250 allow larger amounts of the fed plastic material and the molten plastic material to be processed in view of manufacturing large objects.

[0142] The screw 241, which is shown in more detail in FIG. 10, is made up of a central shaft 243 provided with protruding elements 244. In the embodiment shown, these protruding elements 244 are a thread 244, but in other embodiments, if so desired, other suitable protruding elements known to the person skilled in the art may be used that fulfill the function of transporting and mixing the fed plastic material and the molten plastic material.

[0143] The screw 241 is divided into different screw zones 245, 246, 247 that are adapted for different phases in the process of transporting and melting the fed plastic material, which phases take place in the different zones 251, 252, 253 of the barrel 250. Thus, the first screw zone 245 is adapted for retracting the fed plastic material in the first zone 251 of the barrel 250, the second screw zone 246 is adapted for the process of melting the retracted plastic material in the second zone 252 of the barrel 250, and the third screw zone 247 is adapted for pumping the molten plastic material along to the nozzle 230. In alternative embodiments, the screw may also be provided with fewer screw zones or with additional screw zones that are adapted for possible additional phases of transporting and melting the fed plastic material.

[0144] To this end, in the embodiment shown, the diameter of the central shaft 243 increases and the width of the thread 244 increases from the first screw zone 245 toward the third screw zone 247. As a result, per each screw zone 245, 246, 247, there is less available space between the screw 241 and the wall of the barrel 250. This is because in the first screw zone 245, this space needs to be of sufficient size to allow enough of the fed plastic material to be pulled into the barrel 250 as a granulated material, a regranulated material, a ground material and/or a densified material, taking into account the open space between the fed pieces of plastic material, in order to obtain a continuous flow of the molten plastic material further at the output opening 231 of the nozzle 230. At the level of the second screw zone 246, the available space becomes smaller in order to press the retracted plastic material, which is already starting to melt, closer together. At the level of the third screw zone 247, the available space becomes even smaller, in order to bring the molten plastic material properly together and thus allow a continuous flow of molten plastic material to be pumped to the nozzle 230. In alternative embodiments of the screw, other properties than the diameter of the central shaft and the width of the thread may also be adapted to the different phases in the process of melting and transporting the plastic, such as for example the type of protruding elements, the shape and/or dimensions of the protruding elements, the shape and/or dimensions of the central shaft, the diameter of the screw, and/or the material of the screw.

[0145] In the embodiment shown, the screw 241 is made up of a single piece, but in alternative embodiments, the screw may also be constructed in a modular fashion from interchangeable elements that each provide a different screw zone. This allows the screw to be repaired or modified for use in different circumstances in a simple way.

[0146] In the embodiment shown, the conveyor 240 comprises a single screw 241. In alternative embodiments, however, the conveyor 240 may be provided with multiple screws. One possibility is, for example, the use of two screws arranged parallel and adjacent to each other, wherein the two screws rotate in the same direction of rotation or in opposite directions of rotation.

[0147] The motor 249 is arranged to rotate the screw 241 at least in a first direction of rotation, wherein the fed plastic material and the molten plastic material are transported through the barrel 250 in a direction from the feeder 210 to the nozzle 230, and in particular the output opening 231 of the nozzle. The motor 249 may also be arranged to rotate the screw in a second direction of rotation, opposite to the first direction of rotation, wherein the fed plastic material and the molten plastic material are transported through the barrel 250 in a reverse direction from the nozzle 230 to the feeder 210. The latter may be useful for temporarily stopping the flow of molten plastic material from the nozzle 230 to allow the object to be moved during its additive manufacturing. This prevents unwanted molten plastic material from continuing to flow from the nozzle 230 in the meantime. If so desired, for the same reason, the nozzle 230 may also be provided with a closing element (not shown) for opening and closing the output opening 231. Preferably, the motor 249 is provided with positioning, and the motor 249 is arranged for driving the screw 241 with an adjustable torque that can be kept constant while driving the screw 241. This allows the flow of molten plastic material from the output opening 231 of the nozzle 230 to be controlled and adjusted precisely. To this end, a servomotor is preferably used as the motor 249. The motor 249 is directly connected to the screw 241 and the axis of rotation of the motor 249 is located as an extension of the screw 241 for optimal transmission from the motor 249 to the screw 241.

[0148] The nozzle 230 of the plasticizer 200, shown in more detail in FIG. 8, comprises a main body 232 that is connected to the barrel 250 and from there extends downward along the vertical direction V, and at a bottom end of the main body 232, the nozzle 230 is provided with a head 233 having the output opening 231. The nozzle 230 extends from the first compartment 110 of the system 100 to the second compartment 120 of the system 100. The nozzle 230 is tiltably attached to the barrel 250 by means of a ball joint 270. The ball joint 270 allows the nozzle 230 to be tilted relative to the further plasticizer 200 at times when the system 100 is not currently involved in the additive manufacturing of an object. During additive manufacturing of an object, on the other hand, the nozzle 230 remains in the same position relative to the further plasticizer 200. This allows the nozzle 230 to be placed, prior to starting the additive manufacturing of a certain type of object, into a desired position that is beneficial for additive manufacturing of that specific type of object.

[0149] The nozzle 230 is provided with an expansion space 260 in the main body 233. The expansion space 260 extends along the vertical direction V through the main body 232 as a conduit for the molten plastic material. The expansion space 260 thereby extends from a passage duct 255 for the molten plastic material out of the barrel 250 to an output duct 235 for the molten plastic material in the head 233 of the nozzle 230. The expansion space 260 has a diameter d3 that is larger than the diameter d2 of the upstream passage duct 255 and the diameter d4 of the downstream output duct 235. Thus, the expansion space 260 forms a buffer for accommodating changes in the flow of the molten plastic material from the barrel 250, so that at the output opening 231 of the nozzle 230, an even flow of the molten plastic material can be expelled. Preferably, the expansion space 260 is dimensioned so that it provides a buffer for the ejection of molten plastic material out of the barrel 250 as a result of multiple revolutions of the screw 241 in the barrel 250, preferably at least two revolutions, preferably at least three revolutions.

[0150] If so desired, the expansion space 260 may be arranged so that its volume is adjustable, which allows responding to larger fluctuations in the flow of the molten plastic material from the barrel 250, so that even in these circumstances, an even flow of the molten plastic material can be obtained at the output opening 231 of the nozzle 230. An expansion space 260 provided in such a way makes it possible to respond to a large increase in the flow of the molten plastic material by increasing the volume of the expansion space 260, and to respond to a large decrease in the flow of the molten plastic material by decreasing the volume of the expansion space. Preferably, the volume of the expansion space is adjusted in such a way that a predetermined pressure can be maintained at the output opening 230 of the nozzle 230.

[0151] The adjustable volume of the expansion space 260 also, if so required by the application, allows the pressure of the molten plastic material at the output opening 231 of the nozzle 230 to be adjusted temporarily, for example to make it possible to temporarily eject a larger or smaller amount of the molten plastic material from the nozzle 230. This may for example be useful if, during additive manufacturing of the object, more or less of the molten plastic material is to be applied at certain positions in the object. This can also be used as a fine tuning of the amount of ejected molten plastic material, combined with a coarse tuning by adjusting the rotation speed of the screw 421 of the plasticizer 200.

[0152] Adjusting the volume of the expansion space 260 can for example be carried out by providing the walls of the expansion space 260 with one or more slidable wall sections that can be slid into the expansion space 260 to decrease the volume of the expansion space 260, and that can be slid out of the expansion space 260 to increase the volume of the expansion space 260. Such slidable wall sections may for example be bimetal elements in the wall of the expansion space 260, which, as it were, form “muscles” that can contract and relax the wall of the expansion space for respectively decreasing and increasing the volume of the expansion space 260. However, the slidable wall sections can also be provided in other ways, for example in the form of a membrane or of a piston or any other variable actuator in an opening in the wall.

[0153] The plasticizer 200 comprises a controller for controlling the adjustment of the volume of the expansion space 260 in such a way that a predetermined pressure is maintained in the molten plastic material at the output opening 231 of the nozzle 230. To allow the volume of the expansion space 260 to be adjusted, the controller is operationally connected to the slidable wall sections or any other mechanism for adjusting the volume of the expansion space 260. To allow the adjustment of the volume of the expansion space 260 to be controlled so as to achieve a predetermined pressure in the molten plastic material at the output opening 231 of the nozzle 230, the controller is provided with pressure sensors in the barrel 250, the expansion space 260 and the head 233 of the nozzle 230. The pressure in the molten plastic material measured by these pressure sensors offers an indication of the pressure in the molten plastic material at the output opening 231 of the nozzle 230, based on which the controller can adjust the volume of the expansion space 260 if this indication deviates from the predetermined pressure. The pressure sensor in the head 233 of the nozzle 230 offers a direct indication of the pressure in the molten plastic material at the output opening 231 of the nozzle 230, as this pressure sensor is located directly at the output opening 231. The pressure sensors in the barrel 250 and the expansion space 260 do not offer a direct indication of the pressure in the molten plastic material at the output opening 231 of the nozzle 230, but make it possible to predict an expected pressure in the molten plastic material, based on which the volume of the expansion space 260 can then be adjusted to allow an early response to pressure changes before they even occur at the output opening 231 of the nozzle 230.

[0154] The pressure measured by the pressure sensor in the barrel 250 offers an indication of pressure changes to be expected in the expansion space 260, which allows the controller to adjust the volume of the expansion space 260 in a timely manner to compensate for these pressure changes. The pressure measured by the pressure sensor in the expansion space 260 offers a direct indication of pressure changes in the expansion space 260, which allows the controller to directly adjust the volume of the expansion space 260 to prevent these pressure changes from propagating to the output opening 231 of the nozzle 230. These pressure sensors can be used separately for the specified purpose, but the combination of the pressure sensors offers the advantage that along het trajectory of the flow of the molten plastic material, different checks may be carried out to verify whether the adjustments of the volume of the expansion space 260 have the desired effect. Thus, the pressure sensor in the expansion space 260 can be used to check if volume adjustments of the expansion space 260 based on the pressure measured by the pressure sensor in the barrel 250 have the desired effect, and the pressure sensor in the head 233 of the nozzle 230 can be used to check if volume adjustments of the expansion space 260 based on the pressure measured by the pressure sensor in the barrel 250 and/or the expansion space 260 have the desired effect.

[0155] As already mentioned above, the actual process of additive manufacturing of the object mainly takes place in the second compartment 120. To this end, in the second compartment 120, the system 100 is provided with a printing bed 300 having a printing plate 310 arranged for applying the molten plastic material from the nozzle 230 of the plasticizers 200 thereon for additive manufacturing of the object. The printing plate 310 has a diameter of approximately 1.5 m. The shown embodiment of the system 100 is arranged for additively manufacturing an object on the printing plate 310 up to a height of approximately 0.75 m, such that the object can occupy a volume of approximately 1.3 m.sup.3.

[0156] The plasticizer 200 is arranged, when applying the molten plastic material 800 onto the printing plate 310 or onto a layer of plastic material of the object to be additively manufactured that was previously applied onto the printing plate 310, to smear the ejected molten plastic material 800 onto the printing plate 310 or the layer of plastic material that was already applied. To this end, the head 233 of the nozzle 230, as shown in the FIGS. 9A and 9B, is provided at a bottom end with a smearing surface 234 extending around the output opening 231. The smearing surface 234 preferably has a diameter d5 in the range of 16-30 mm, preferably, but not necessarily depending on the diameter d4 of the output opening 231 of the nozzle 230. The smearing surface 234 may for example be a flat surface having rounded corners that extends in the plane of the output opening 231, as shown in FIG. 9A, or a curved convex surface, as shown in FIG. 9B, but other shapes are also possible.

[0157] For the smearing, the printing plate 310 or the layer of plastic material that was already applied is brought close to the head 233 of the nozzle 230, and the molten plastic material 800 is expelled from the output opening 231 at a relatively high predetermined pressure, causing the molten plastic material 800 to not only flow directly downward from the output opening 231, but also laterally between the smearing surface 234 and the printing plate 310 or the layer of plastic material that was already applied. Here, the predetermined pressure of the molten plastic material at the output opening 231 and the distance between the head 233 of the nozzle 230 and the printing plate 310 or the layer of plastic material that was already applied are mutually attuned in such a way that the ejected molten plastic material 800 does not flow beyond the edges of the smearing surface 234. When compared to a nozzle in which the molten plastic material only flows directly downward from the output opening, this allows a wider, yet uniform layer of the molten plastic material 800 to be applied onto the printing plate 310 or the layer of plastic material that was already applied.

[0158] For smearing the ejected molten plastic material 800 onto the printing plate 310 or the layer of plastic material that was already applied, the first conditioner 220, as shown in FIGS. 7 and 8, is preferably arranged for heating the head 233 of the nozzle 230 independently of the main body 232. This allows the heating of the main body 232 to be specifically attuned for keeping the molten plastic material in the expansion space 260 in the main body 232 of the nozzle 232 under controlled conditions, and for attuning the heating of the head 233 of the nozzle 230 specifically to the use of the head 233 when smearing the ejected molten plastic material onto the printing plate 310 or the layer of plastic material that was already applied. Thus, the heated head 233 of the nozzle 230 ensures that the ejected molten plastic material 800 remains liquid when smearing the ejected molten plastic material 800 onto the printing plate 310 or the layer of plastic material that was already applied, so that the smearing can occur smoothly without any hitches. The heated head 233 of the nozzle 230 also ensures that no solidified residues of the ejected molten plastic material 800 can remain on the head 233 of the nozzle 230 that would interfere with the proper application of the ejected molten plastic material 800 onto the printing plate 310 or the layer of plastic material that was already applied.

[0159] In the second embodiment of the system 100, shown in the FIGS. 3-6, the printing plate 310 is an interchangeable printing plate 310. The use of an interchangeable printing plate 310 makes it possible, after additively manufacturing an object, to lay aside the printing plate 310 together with the object on a depositing device 700 of the system 100 provided for that purpose, after which a new printing plate 310 can then quickly be placed onto the printing bed 300, so that additive manufacturing of a next object can immediately be started. This does not require waiting for the previously manufactured object to be fully hardened and removing it from the printing plate 310. The hardening can take place undisturbed on the printing plate 310 that was set aside, while the next object is already being manufactured on the new printing plate 310. To allow a new printing plate 310 to be quickly put in position, storages 600 are provided in the second compartment 120 in which a supply of the interchangeable printing plates 310 can be stored.

[0160] In the embodiments shown, the printing bed 300 is divided into a number of control zones 311, as can for example be seen in the unused printing bed 300 in FIG. 4. The control zones 311 can be heated and cooled independently of each other by means of a second conditioner (not shown) of the system 100. The second conditioner allows the different parts of the object to be kept at a constant temperature during additive manufacturing thereof, so that no excessive differences in temperature can occur between the different parts of the object, which could lead to defects.

[0161] In the second compartment 120, a third conditioner (not shown) may also be provided outside of the nozzle 230 at the output opening 231. This third conditioner is arranged for conditioning the flow of molten plastic material being expelled from the nozzle 230. This is to bring the flow of molten plastic material in the optimal condition for additive manufacturing of the object. The conditioning of the flow may for example be carried out by adjusting the temperature, adjusting the atmospheric humidity or adjusting the composition of the air near the output opening 231 of the nozzle 230.

[0162] In the second compartment 120, a fourth conditioner (not shown) may also be provided. This fourth conditioner is arranged for conditioning the environmental conditions in the second compartment 120. This is to bring the environment in the second compartment 120 in the optimal condition for additive manufacturing of the object. The conditioning of the environmental conditions in the second compartment 120 may for example be carried out by adjusting environmental parameters, such as temperature or atmospheric humidity.

[0163] The printing bed 300 is supported by a first support device 400 of the system 100, which is arranged for moving the printing bed 300 according to 6 independent degrees of freedom, being 3 translational degrees of freedom and 3 rotational degrees of freedom. The support device 400 arranged in this way allows the printing bed 300 to always be positioned relative to the nozzle 230 of the plasticizer 200 during additive manufacturing of the object that the parts of the object still to be manufactured are always optimally supported while applying them onto the printing bed 300 or onto the already manufactured parts of the object. Preferably, the first support device 400 is further arranged for simultaneously moving the printing bed 300 according to at least 3 degrees of freedom, so that the printing bed 300 and the object arranged thereon can be moved smoothly during additive manufacturing of the object. In the embodiment shown, a robotic arm 410 is used for the first support device 400, but in alternative embodiments, other suitable support devices known to the person skilled in the art may also be used for supporting and moving the printing bed 300.

[0164] The system 100 is configured such that the output opening 231 of the nozzle 230 of each plasticizer 200, at least during additive manufacturing of the object, is located in a predetermined fixed position in the system 100. Here, at least one point of the output opening 231 is located in a predetermined fixed position in the system 100. The at least one point is preferably a central point or any other predetermined point of the output opening 231. In the case of a circular output opening 231, the at least one point may for example be the center of the circular opening.

[0165] In this configuration of system 100, the movements of the plasticizer 200 and the printing bed 300 relative to each other that are required for additive manufacturing of the object are mainly carried out by moving the printing bed 300. The plasticizer 200 remains positioned in a fixed position or is optionally tiltable to a limited degree, thus avoiding disruptions in the flow of the molten plastic material from the nozzle 230 which could be caused by unnecessary movements of the plasticizer 200.

[0166] To this end, the plasticizer 200 may be mounted in a fixed position in the system 100, so that the output opening 231 of the nozzle 230 as a whole is not movable. In an alternative embodiment, the plasticizer 200 may be mounted onto a second support device (not shown) that is arranged for tilting the plasticizer 200, but controlled by a control unit (not shown) of the system 100 in such a way that the output opening 231 remains at the predetermined position during additive manufacturing of an object. In this embodiment, the output opening 231 is tiltable but not translatable. Tilting the output opening 231 may be advantageous to avoid the need to position the printing bed 300, during additive manufacturing of the object, at all too difficult angles to be able to properly support the object.

[0167] The control unit, which may also be arranged for controlling other parts of the system 100, can be housed, if so desired, in a separate third compartment (not shown) of the system 100. The third compartment is then accessible to users of the system 100 for operating the system 100 by means of the control unit, and the third compartment thereby shields the user from the different parts of the system 100 housed the other compartments 110, 120, which may pose a safety risk for the user. Thus, the user is for example shielded from the robotic arm 410, of which the movements could injure the user, and from the heat and possibly noxious fumes of the plasticizers 200.

[0168] In further embodiments, if so desired, the system 100 may also be provided with a preparation device (not shown) that is arranged for making the plastic to be fed to one or more of the plasticizers 200 suitable for use in the respective plasticizers 200. If so desired, the preparation device can be housed in a fourth compartment (not shown) of the system.

TABLE-US-00001 References 100 system 253 third zone 200 plasticizer 255 passage duct 210 feeder 260 expansion space 211 feed opening 270 ball joint 215 agitator 300 printing bed 220 first conditioner 310 printing plate 230 nozzle 311 control zones 231 output opening 400 first support device 232 main body 410 robotic arm 233 head 600 storage 234 smearing surface 700 depositing device 235 output duct 800 molten plastic material 240 conveyor 110 first compartment 241 screw 120 second compartment 243 central shaft 150 station 244 protruding elements 160 container 245 first screw zone H horizontal direction 246 second screw zone V vertical direction 247 third screw zone d1 outer diameter screw 249 motor d2 diameter passage duct 250 barrel d3 diameter expansion space 251 first zone d4 diameter output opening 252 second zone d5 diameter smearing surface