A 3D printer comprising a detaching mechanism

Abstract

A 3D printer (1) for printing an object (OBJ), the 3D printer comprising a carrier platform (2) configured to be heated to a printing temperature for printing the object (OBJ), the carrier platform (2) comprising a set of one or more magnets (3); a flexible sheet (4) configured to support the object (OBJ), the flexible sheet comprising a protruding portion (5); a detaching mechanism (6); and an actuation mechanism (7) being movable between a printing position and a lifting position, the actuation mechanism (7) being coupled to one of the carrier platform (2) and the detaching mechanism (6) in such a way that the one of the carrier platform (2) and the detaching mechanism (6) is moved with the actuation mechanism (7) when the actuation mechanism (7) is moved between the printing position and the lifting position. In the printing position of the actuation mechanism (7), the flexible sheet (4) is attached to the carrier platform (2) as a result of a magnetic force applied by the set of magnets (3) on the flexible sheet (4); the protruding portion (5) protrudes from the carrier platform (2); and the detaching mechanism (6) is decoupled from the protruding portion (5). In the lifting position of the actuation mechanism (7), the detaching mechanism (6) is abutting or in engagement with the protruding portion (5); and the flexible sheet (4) is detached, at least partially, from the carrier platform (2) as a result of a force applied by the detaching mechanism (6) on the protruding portion (5) and counteracting the magnetic force.

Description

[0001] A 3D PRINTER COMPRISING A DETACHING MECHANISM

[0002] FIELD OF THE INVENTION

[0003] The present invention relates generally to a 3D printer, and more specifically to a 3D printer comprising a detaching mechanism. The present invention further relates to a 3D printing method.

[0004] BACKGROUND OF THE INVENTION

[0005] Three dimensional (3D) printing, also known as additive manufacturing, has revolutionized various industries by enabling the rapid prototyping and production of complex objects with unprecedented precision and customization.

[0006] 3D printers typically comprise a substrate upon which layers of a printing material are sequentially deposited in order to print an object. During a printing cycle, the substrate needs to be at an elevated printing temperature in order to prevent undesired effects, such as poor adhesion of the first layer to the substrate or warping of the layers. After the object has been printed, it has to cool down sufficiently to be removed from the substrate. However, to let the printed object cool down, the substrate is usually cooled down as well. As a result, after removal of the printed object from the substrate, the substrate needs to heat up again before a new printing cycle may commence, which leads to undesirably long and energy-consuming printing cycles.

[0007] US 2015 / 145174 Al discloses a platen assembly for use in an additive manufacturing system, which includes a platen plate that is preferably secured to a gantry mechanism of the additive manufacturing system. The platen gantry is configured to magnetically couple interchangeable and replaceable build sheets to the top surface of the platen plate. The magnetically coupled build sheets are configured to receive the printed layers from the printing mechanism. US 2015 / 145174 Al further discloses a method for using the platen assembly in an additive manufacturing system. According to the method, the first build sheet with the printed three-dimensional part is removed from the top surface of the platen plate and the first build sheet is subsequently flexed to delaminate the three- dimensional part from the first build sheet. The removal and subsequent replacement of the build sheets lengthen the printing times, besides making the system disadvantageously complex. Ultimately, the long printing times increase the energy consumption of the system as well. Furthermore, removing the first build sheet before the printed three-dimensional part has cooled down sufficiently may lead to warping or cracking of the printed three-dimensional part.

[0008] SUMMARY OF THE INVENTION

[0009] Therefore, it is desirable to provide a 3D printer and a 3D printing method which reduce the time and energy required for one or more printing cycles.

[0010] Furthermore, it is desirable to provide a 3D printer configured to measure whether the printed object has cooled down sufficiently, thereby preventing a premature removal of the object from the substrate.

[0011] According to a first aspect of the invention, a 3D printer for printing an object is provided. The 3D printer comprises a carrier platform, a flexible sheet, a detaching mechanism, and an actuation mechanism. The carrier platform is configured to be heated to a printing temperature for printing the object and comprises a set of one or more magnets. The flexible sheet is configured to support the object and comprises a protruding portion. The actuation mechanism is movable between a printing position and a lifting position.

[0012] The actuation mechanism is coupled to one of the carrier platform and the detaching mechanism in such a way that the actuation mechanism is configured to move the detaching mechanism with respect to the carrier platform and the flexible sheet, or the actuation mechanism is configured to move the carrier platform and the flexible sheet with respect to the detaching mechanism. Consequently, the one of the carrier platform and the detaching mechanism that the actuation mechanism is coupled to is moved with the actuation mechanism when the actuation mechanism is moved between the printing position and the lifting position.

[0013] In the printing position of the actuation mechanism, the flexible sheet is attached to the carrier platform as a result of a magnetic force applied by the set of magnets on the flexible sheet. The protruding portion protrudes from the carrier platform and the detaching mechanism is decoupled from the protruding portion so that any force applied by the detaching mechanism on the protruding portion is insufficient for counteracting the magnetic force.

[0014] In the lifting position of the actuation mechanism, the detaching mechanism is abutting or in engagement with the protruding portion so that a force applied by the detaching mechanism on the protruding portion is sufficient for counteracting the magnetic force, and for detaching, at least partially, the flexible sheet from the carrier platform.

[0015] It will be appreciated that the actuation mechanism is configured to function in synergy with the detaching mechanism. This synergy provides a simple and effective way to detach the flexible sheet, at least partially, from the carrier platform, and attach it back to the carrier platform when the actuation mechanism moves back from the lifting position to the printing position. As a result, after an object has been printed and removed from the flexible sheet, there is no need to change or replace the flexible sheet, and the printing of a new object may commence right afterwards. Therefore, not only is the complexity of a 3D printer reduced, the printing of one or more objects is also speeded up. As a result of the reduced printing time, the energy consumption of the 3D printer is also reduced.

[0016] Since, in the lifting position of the actuation mechanism, the flexible sheet is detached, at least partially, from the carrier platform, the flexible sheet may cool down, thereby making the printed object cool down as well. On the other hand, the carrier platform may remain heated up at the printing temperature. After the printed object has cooled down sufficiently, it may be removed from the flexible sheet, and the printing of another object may commence. It will be appreciated that the heat capacity of the flexible sheet may be smaller than the heat capacity of the carrier platform. As a result, the heat exchange required to induce a given variation in the temperature of the flexible sheet is smaller than the heat exchange required to induce the same variation in the temperature of the carrier platform. Therefore, the time required for the object to be printed and to cool down sufficiently before being removed is reduced as compared to the case wherein the flexible sheet were not to detach, at least partially, from the carrier platform, and the carrier platform were to heat up and, subsequently, cool down.

[0017] The detaching mechanism may comprise a temperature sensor configured to measure a temperature of the flexible sheet in the lifting position of the actuation mechanism.

[0018] By measuring the temperature of the flexible sheet, it may be assessed whether the object has cooled down enough to be removed from the flexible sheet. As a result, unnecessarily long waiting times before the removal of the object are avoided. Furthermore, a premature removal of the object from the flexible sheet is prevented. Such a premature removal is undesirable, because it may result in warping or cracking of the object and, generally, jeopardize the quality of the printed object. The flexible sheet comprises at least a first edge, a second edge, and a third edge. The flexible sheet may be connected to the carrier platform by at least one hinge connection arranged on the first edge of the flexible sheet.

[0019] The hinge connection ensures that the flexible sheet is reattached to the carrier platform when the actuation mechanism is moved back from the lifting position to the printing position, particularly that the flexible sheet is reattached to the carrier platform in the correct position. Furthermore, the hinge connection contributes to prevent the formation of folds on the flexible sheet in the printing position of the actuation mechanism. These folds are undesirable, as they may jeopardize the quality of the printed object.

[0020] The detaching mechanism comprises a first rod-shaped element and a second rod-shaped element, the first rod-shaped element and the second rod-shaped element being arranged extending perpendicularly to the carrier platform.

[0021] The protruding portion comprises a first protruding section arranged at the second edge of the flexible sheet, and a second protruding section arranged at the third edge of the flexible sheet.

[0022] In the printing position of the actuation mechanism, the first rod-shaped element is at a distance from the first protruding section, and the second rod-shaped element is at a distance from the second protruding section. Alternatively, in the printing position of the actuation mechanism, the first rod-shaped element touches the first protruding section, and the second rod-shaped element touches the second protruding section. Any of these alternatives is suitable, as long as in the printing position of the actuation mechanism any force applied by the detaching mechanism on the protruding portion is insufficient for counteracting the magnetic force by which the flexible sheet is attached to the carrier platform.

[0023] In the lifting position of the actuation mechanism, the first rod-shaped element is abutting or in engagement with the first protruding section, the second rod-shaped element is abutting or in engagement with the second protruding section, and each of the first rodshaped element and the second rod-shaped element apply a force in a direction perpendicular to the carrier platform.

[0024] The first rod-shaped element and second rod-shaped element as described above provide a simple detaching mechanism. Not only do they automate the at least partial detaching of the flexible sheet, thereby streamlining the printing process, they also do it without any unnecessary complexity. Moreover, the orientation of the first rod-shaped element and second rod-shaped element with respect to the carrier platform, and the interaction of the first rod-shaped element and second rod-shaped element with the first protruding section and second protruding section, respectively, is advantageous for applying a force which effectively decouples the flexible sheet from the carrier platform in the lifting position of the actuation mechanism.

[0025] The first rod-shaped element may comprise a first temperature sensor, and the second rod-shaped element may comprise a second temperature sensor. The first temperature sensor and the second temperature sensor are configured to measure a temperature of the flexible sheet in the lifting position of the actuation mechanism.

[0026] The use of a first temperature sensor and a second temperature sensor, measuring a temperature of the flexible sheet from the first protruding section and second protruding section, respectively, may improve the accuracy of the measurement as compared to the use of a single temperature sensor.

[0027] In the printing position of the actuation mechanism the flexible sheet lies flat on the carrier platform. In the lifting position of the actuation mechanism, the flexible sheet may be curved.

[0028] The flexible sheet lying flat on the carrier platform in the printing position of the actuation mechanism is advantageous because the presence of folds in the flexible sheet while the object is being printed may jeopardize the quality of the printed object. The flexible sheet being curved in the lifting position of the actuation mechanism facilitates the removal the object from the flexible sheet after the printing of the object is completed. It will be appreciated that the flexible sheet is curved automatically when the actuation mechanism moves to the lifting position, which eliminates the need of curving the flexible sheet manually. Therefore, the automatic curving is advantageous for reducing the printing time and the energy consumption of a 3D printer.

[0029] The actuation mechanism may be configured to move the detaching mechanism with respect to the carrier platform and the flexible sheet. Alternatively, the actuation mechanism may be configured to move the carrier platform and the flexible sheet with respect to the detaching mechanism.

[0030] Moving the detaching mechanism with respect to the carrier platform and the flexible sheet, instead of moving the carrier platform and the flexible sheet with respect to the detaching mechanism, may reduce the energy consumption and complexity of a 3D printer if the weigh of the detaching mechanism is less than the total weight of the carrier platform and the flexible sheet. The 3D printer further comprises a printer floor. The first rod-shaped element and the second rod-shaped element may be attached to the printer floor and arranged extending perpendicularly to the printer floor. The carrier platform may be arranged extending parallelly to the printer floor. In the printing position of the actuation mechanism, the carrier platform is spaced apart from the printer floor by a first separation distance. In the lifting position of the actuation mechanism, the carrier platform is spaced apart from the printer floor by a second separation distance which may be smaller than the first separation distance.

[0031] The printer floor as described above supports the first rod-shaped element and the second rod-shaped element, thereby improving the mechanical robustness and durability of a 3D printer.

[0032] In the printing position of the actuation mechanism each of the first rodshaped element and the second rod-shaped element has a respective first length. In the lifting position of the actuation mechanism, each of the first rod-shaped element and the second rodshaped element has a respective second length which may be larger than the respective first length.

[0033] Since the first rod-shaped element and second rod-shaped element as described above are telescopic, a light and simple detaching mechanism is provided which may be moved with respect to the carrier platform and the flexible sheet.

[0034] The flexible sheet may comprise a ferromagnetic material.

[0035] A ferromagnetic material is advantageous in that it provides a simple way of magnetically attaching the flexible sheet to the carrier platform in the printing position of the actuation mechanism.

[0036] The flexible sheet may have a thickness in a range of 0.1 mm to 1 mm.

[0037] The thickness range disclosed above improves the flexibility of the flexible sheet, thereby reducing the risk that the flexible sheet may break or be damaged while being curved in the lifting position of the actuation mechanism. Furthermore, the thickness range disclosed above increases the speed at which the flexible sheet may heat up in the printing position of the actuation mechanism and cool down in the lifting position of the actuation mechanism. As a result, the printing time and the energy consumption of a 3D printer are reduced.

[0038] The set of magnets may be arranged in a regular pattern such that, in the printing position of the actuation mechanism, the flexible sheet is flat. The regular patern of the set of magnets as described above is conducive to prevent the formation of folds on the flexible sheet in the printing position of the actuation mechanism. These folds are undesirable, as they may jeopardize the quality of the printed object.

[0039] At least one of the one or more magnets of the set of magnets may be a neodymium magnet.

[0040] As compared to other types of magnets, neodymium magnets can operate at larger temperatures, thereby extending the operating temperature and durability of a 3D printer.

[0041] The invention further relates to a 3D printing method comprising the steps of: a. heating the carrier platform to a printing temperature for printing the object; b. bringing the actuation mechanism into the printing position, in which the flexible sheet is attached to the carrier platform as a result of a magnetic force applied by the set of magnets on the flexible sheet, and the protruding portion is decoupled from the detaching mechanism; c. printing the object by depositing a printing material on the flexible sheet; d. bringing the actuation mechanism into the lifting position, in which the detaching mechanism abuts or engages with the protruding portion and the flexible sheet is detached, at least partially, from the carrier platform due to a force applied by the detaching mechanism on the protruding portion and counteracting the magnetic force; e. letting the flexible sheet and the printed object cool to a predetermined temperature; and f. removing the object from the flexible sheet.

[0042] The method may further comprise repeating steps b. to f. an integer number of times equal to or larger than one.

[0043] It is noted that the invention relates to all possible combinations of features recited in the claims.

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0045] This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention. Fig. la shows a side view of a 3D printer according to the invention. The 3D printer comprises an actuation mechanism and a carrier platform. The actuation mechanism is coupled to the carrier platform, and the actuation mechanism is in a printing position.

[0046] Fig. lb shows a side view of the 3D printer in Fig. lb when the actuation mechanism is in a lifting position.

[0047] Fig. 2 shows a top view of the flexible sheet of the 3D printer according to an embodiment of the invention.

[0048] Fig. 3 shows a perspective view of the 3D printer in Fig. lb.

[0049] Fig. 4a shows a side view of another 3D printer according to the invention.

[0050] The 3D printer comprises an actuation mechanism and a detaching mechanism. The actuation mechanism is coupled to the detaching mechanism, and the actuation mechanism is in a printing position.

[0051] Fig. 4b shows a side view of the 3D printer in Fig. 4a when the actuation mechanism is in a lifting position.

[0052] Fig. 5 shows a perspective view of another 3D printer according to the invention.

[0053] Fig. 6 shows a block diagram illustrating a 3D printing method according to the invention.

[0054] As illustrated in the figures, the sizes of layers and regions are exaggerated for illustrative purposes and, thus, are provided to illustrate the general structures of embodiments of the present invention. Like reference numerals refer to like elements throughout.

[0055] DETAILED DESCRIPTION OF THE DRAWINGS

[0056] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0057] Fig. la and Fig. lb illustrate side views of a 3D printer 1 for printing an object OBJ according to the invention. Fig. 3 shows a perspective view of the 3D printer 1. The 3D printer 1 comprises a carrier platform 2, a flexible sheet 4, a detaching mechanism 6 and an actuation mechanism 7. The carrier platform 2 is configured to be heated to a printing temperature for printing the object OBJ. The carrier platform 2 comprises a set of one or more magnets 3. The flexible sheet 4 is configured to support the object OBJ. The flexible sheet 4 comprises a protruding portion 5. The actuation mechanism 7 is movable between a printing position (Fig. la) and a lifting position (Fig. lb). The actuation mechanism 7 is coupled to the carrier platform 2 in such a way that the carrier platform 2 is moved with the actuation mechanism 7 when the actuation mechanism 7 is moved between the printing position and the lifting position. Fig. la and Fig. lb show a side view of the 3D printer 1 when the actuation mechanism 7 is in the printing position and lifting position, respectively. Fig. 3 shows a perspective view of the 3D printer 1 when the actuation mechanism 7 is the lifting position. As the actuation mechanism 7 is moved from the printing position to the lifting position, the distance between the detaching mechanism 6 and the flexible sheet 4 is reduced.

[0058] As shown in Fig. la, in the printing position of the actuation mechanism 7 the flexible sheet 4 is attached to the carrier platform 2 as a result of a magnetic force applied by the set of magnets 3 on the flexible sheet 4. The protruding portion 5 protrudes from the carrier platform 2 and the detaching mechanism 6 is decoupled from the protruding portion 5. The set of magnets 3 is strong enough for the flexible sheet 4 to lie flat on the carrier platform 2. This is advantageous because the presence of folds in the flexible sheet 4 while the object OBJ is being printed may jeopardize the quality of the object OBJ.

[0059] As shown in Fig. lb, in the lifting position of the actuation mechanism 7 the detaching mechanism 6 abuts the protruding portion 5. The flexible sheet 4 is partially detached from the carrier platform 2 as a result of a force applied by the detaching mechanism 6 on the protruding portion 5 and counteracting the magnetic force applied by the set of magnets 3. Therefore, the flexible sheet 4 is curved. As further explained later, this is advantageous for removing the object OBJ from the flexible sheet 4 after the printing of the object OBJ is completed.

[0060] As shown in Fig. la and Fig. lb, the actuation mechanism 7 comprises pneumatic actuators. However, other forms of the actuation mechanism 7 are conceivable, such as hydraulic actuators, lead screws, or belts engaging with a system of pulleys.

[0061] The detaching mechanism 6 comprises a first rod-shaped element 13 and a second rod-shaped element 14, the first rod-shaped element 13 and the second rod-shaped element 14 being arranged extending perpendicularly to the carrier platform 2. The 3D printer 1 further comprises a printer floor 17. The carrier platform 2 is arranged extending parallelly to the printer floor 17. The first rod-shaped element 13 and the second rod-shaped element 14 are attached to the printer floor 17 and arranged extending perpendicularly to the printer floor 17. As shown, the detaching mechanism 6 comprises a detachment element in the form of an end or surface configured for abutting the protruding portion 5 in the lifting position of the actuation mechanism 7. As shown, two detachment elements are provided. However, other detaching elements are conceivable, such as hooks, levers, or gripping stands, configured to abut or engage with the protruding portion 5 in the lifting position of the actuation mechanism 7. Furthermore, in order to facilitate the at least partial detaching of the flexible sheet 4 from the carrier platform 2 in the lifting position of the actuation mechanism 7, it is conceivable that the detaching mechanism 6 may comprise more than two detaching elements or even only one detaching element.

[0062] As shown in Fig. la, in the printing position of the actuation mechanism 7 the carrier platform 2 is spaced apart from the printer floor 17 by a first separation distance 18a. As shown in Fig. lb, in the lifting position of the actuation mechanism 7, the carrier platform 2 is spaced apart from the printer floor 17 by a second separation distance 18b being smaller than the first separation distance 18a.

[0063] As illustrated by Fig. 2, showing a top view of the flexible sheet 4, the flexible sheet 4 comprises at least a first edge 9, a second edge 11 and a third edge 12. The protruding portion 5 comprises a first protruding section 15 arranged at the second edge 11 of the flexible sheet 4, and a second protruding section 16 arranged at the third edge 12 of the flexible sheet 4. In the printing position of the actuation mechanism 7 (cf. Fig. la), the first rod-shaped element 13 is at a distance from the first protruding section 15. The second rodshaped element 14 is at a distance from the second section 16.

[0064] In an alternative configuration for the printing position of the actuation mechanism, not shown in the aforementioned figures, the first rod-shaped element 13 touches the first protruding section 15, and the second rod-shaped element 14 touches the second protruding section 16.

[0065] In bot configurations for the printing position of the actuation mechanism, the detaching mechanism 6 is decoupled from the protruding portion 5 so that any force applied by the detaching mechanism 6 on the protruding portion 5 is insufficient for counteracting the magnetic force.

[0066] In the lifting position of the actuation mechanism 7 (cf. Fig. lb), the first rodshaped element 13 abuts the first protruding section 15. The second rod-shaped element 14 abuts the second protruding section 16. In the lifting position of the actuation mechanism 7, each of the first rod-shaped element 13 and the second rod-shaped element 14 applies a force in a direction perpendicular to the carrier platform 2. The orientation of this force is advantageous to effectively counteract the magnetic force applied by the set of magnets 3.

[0067] As further illustrated by Fig. 2, the third edge 12 extends perpendicularly to the second edge 11, and the second edge 11 extends parallelly to the first edge 9. The second edge 11 is spaced apart from the first edge 9 in a direction parallel to the third edge 12. The arrangement of the first edge 9, second edge 11 and third edge 12 in relation to each other, as well as in relation to the first protruding section 15 and second protruding section 16, is such that the curving of the flexible sheet 4 in the lifting position of the actuation mechanism 7 is facilitated. Furthermore, this arrangement contributes to prevent the formation of folds on the flexible sheet 4 in the printing position of the actuation mechanism 7.

[0068] Fig. 6 shows a block diagram illustrating steps of a 3D printing method according to the invention. The 3D printing method employs a 3D printer 1 according to any embodiment of the invention. Irrespective of the embodiment, the 3D printing method comprises the following steps.

[0069] In step a., the carrier platform 2 is heated to the printing temperature for printing the object OBJ.

[0070] In step b., the actuation mechanism 7 is brought into the printing position, in which the flexible sheet 4 is attached to the carrier platform 2 as a result of the magnetic force applied by the set of magnets 3 on the flexible sheet 4. The protruding portion 5 is decoupled from the detaching mechanism 6. As a result of the physical contact with the carrier platform 2, the flexible sheet 4 is heated to a first temperature, from now on referred to as sheet printing temperature. The sheet printing temperature is high enough to print the object OBJ. The sheet printing temperature is substantially similar to or the same as the printing temperature of the carrier platform 2.

[0071] In step c., the object OBJ is printed by depositing a printing material on the flexible sheet 4.

[0072] In step d., the actuation mechanism 7 is brought into the lifting position, in which the detaching mechanism 6 abuts or engages with the protruding portion 5 and the flexible sheet 4 is detached, at least partially, from the carrier platform 2 due to the force applied by the detaching mechanism 6 on the protruding portion 5 and counteracting the magnetic force.

[0073] In step e., the flexible sheet 4 and the printed object OBJ are cooled to a predetermined temperature, as a result of the at least partial detaching of the flexible sheet 4 from the carrier platform 2. In particular, the flexible sheet 4 is cooled to a predetermined second temperature, from now on referred to as sheet lifting temperature. The sheet lifting temperature may be the ambient temperature. It will be appreciated that, instead, there is no need to cool the carrier platform 2, which may remain heated at the printing temperature of the carrier platform 2.

[0074] In step f., the object OBJ is removed from the flexible sheet 4. In this step, the flexible sheet 4 is at a temperature not larger than the sheet lifting temperature, and the object OBJ has cooled enough to be removed from the flexible sheet 4. It is also conceivable that the object OBJ detaches itself from the flexible sheet 4 as a result of the reduced temperature and the curving of the flexible sheet 4.

[0075] A printing cycle is considered to comprise steps from b. to f. The 3D printing method may comprise more than one printing cycle. In such a case, the method further comprises repeating steps b. to f. an integer number of times equal to or larger than one, the integer number being the number of printing cycles.

[0076] As already mentioned, the 3D printer and the 3D printing method according to the invention are such that, as a result of the at least partial detaching of the flexible sheet 4 from the carrier platform 2, the carrier platform 2 may remain heated at the printing temperature after printing the object OBJ. In such a case, it is only the flexible sheet 4 that, during a printing cycle, undergoes heating and, subsequently, cooling. The advantageous effects of this feature are illustrated in the following.

[0077] The flexible sheet 4 is thinner than carrier platform 2. The flexible sheet 4 typically has a thickness in a range of 0.1 mm to 1 mm. The mass and specific heat capacity of the flexible sheet 4 and carrier platform 2 are typically such that the heat capacity of the flexible sheet 4 is smaller than the heat capacity of the carrier platform 2. As a result, the time required, during a printing cycle, for the flexible sheet 4 to heat up to the sheet printing temperature and, subsequently, cool down to the sheet lifting temperature, is reduced as compared to the case wherein, during a printing cycle, the flexible sheet 4 were not to detach from the carrier platform 2 and the carrier platform 2 were to heat up and, subsequently, cool down. For example, the carrier platform 2 and the flexible sheet 4 may have substantially similar specific heat capacities, but different masses, the mass of the flexible sheet 4 being smaller than the mass of the carrier platform 2.

[0078] Moreover, the time required to start a new printing cycle, after a previous printing cycle has been completed, is also reduced, because the carrier platform 2 is already at the printing temperature at the end of the previous printing cycle. Likewise, the energy required for one or more printing cycles is also reduced, because of the reduced time required for a printing cycle to be completed. Furthermore, during a printing cycle, continuous heating of the carrier platform 2 may consume less energy compared to heating and subsequent cooling of the carrier platform 2, thereby further contributing to the energy saving.

[0079] Furthermore, the at least partial detaching of the flexible sheet 4 from the carrier platform 2 as result of the actuation mechanism 7 being moved from the printing position to the lifting position reduces the time required for a printing cycle to be completed as compared to the case wherein the at least partial detaching of the flexible sheet 4 from the carrier platform 2 were to be performed manually. Thus, the synergy between the actuation mechanism 7 and the detaching mechanism 6 streamlines a printing cycle.

[0080] It will be also appreciated that the material and thickness of the flexible sheet 4 are such that the flexible sheet is curved in the lifting position of the actuation mechanism 7, thereby enabling the at least partial detaching of the flexible sheet 4 from the carrier platform 2. Furthermore, the removal of the object OBJ from the flexible sheet 4 when the flexible sheet 4 is at a temperature not larger than the sheet lifting temperature is facilitated by the flexible sheet 4 being curved.

[0081] Referring back to Fig. la and Fig. lb, it is seen that the first rod-shaped element 13 comprises a first temperature sensor 8a, and the second rod-shaped element 14 comprise a second temperature sensor 8b. The first temperature sensor 8a and the second temperature sensor 8b are configured to measure a temperature of the flexible sheet 4 in the lifting position of the actuation mechanism 7, wherein the first rod-shaped element 13 and second rod-shaped element 14 abuts the first protruding section 15 and second protruding section 16, respectively. Based on the feedback received from the first temperature sensor 8a and second temperature sensor 8b, it may be assessed whether the flexible sheet 4 has cooled down to the sheet lifting temperature and, therefore, whether the object OBJ has cooled down enough to be removed from the flexible sheet 4. For this assessment, in principle, a single temperature sensor 8a, 8b suffices. However, since the two protruding sections 15, 16 are spaced apart from each other, the use of two temperature sensors, measuring the temperature from the two respective protruding sections 15, 16, may improve the accuracy of the measurement of the sheet lifting temperature as compared to the use of a single temperature sensor. To further improve the accuracy, it is also conceivable that the detaching mechanism 6 comprises more than two detaching elements, configured to measure, in the lifting position of the actuation mechanism 7, a temperature of the flexible sheet 4 from more than two respective protruding sections of the protruding portion 5, the protruding sections being spaced apart from each other.

[0082] It will be also appreciated that measuring the temperature of the flexible sheet 4 and assessing accordingly whether the object OBJ has cooled down enough to be removed from the flexible sheet 4 avoid unnecessarily long waiting times before the removal of the object OBJ. Thus, the time required for one or more printing cycles is further reduced. Furthermore, assessing whether the object OBJ has cooled down enough prevents a premature removal of the object OBJ from the flexible sheet 4, which may result in warping or cracking and, generally, jeopardize the quality of the object OBJ.

[0083] As shown in Fig. la and Fig. lb, the flexible sheet 4 is connected to the carrier platform 2 by a hinge connection 10 arranged on the first edge 9 of the flexible sheet 4. The hinge connection 10 secures the flexible sheet 4 to the carrier platform 2. As a result, the hinge connection 10 ensures that the flexible sheet 4 is reattached to the carrier platform 2 when the actuation mechanism 7 is moved back from the lifting position to the printing position. Furthermore, the hinge connection 10 contributes to prevent the formation of folds on the flexible sheet 4 in the printing position of the actuation mechanism 7.

[0084] The set of magnets 3 is arranged in a regular pattern (cf. Figs, la, lb and 3) such that, in the printing position of the actuation mechanism 7, the flexible sheet 4 is flat. A regular pattern is a periodic pattern with a given unit cell, such as a square unit cell, as shown in Figs, la, lb and 3, a rectangular unit cell, or a triangular unit cell. The regular pattern of the set of magnets 3 is conducive to prevent the formation of folds on the flexible sheet 4 in the printing position of the actuation mechanism 7. However, other patterns are also conceivable.

[0085] In the embodiment shown in Figs, la, lb, 2 and 3, the flexible sheet 4 comprises a ferromagnetic material. As a result, the flexible sheet 4 is attached to the carrier platform 2 in the printing position of the actuation mechanism 7 due to the magnetic force applied by the set of magnets 3. Alternatively, the flexible sheet 4 may not comprise ferromagnetic material, and it may instead comprise a second set of one or more magnets arranged such that the flexible sheet 4 lies flat on the carrier platform 2 in the printing position of the actuation mechanism 7.

[0086] In the embodiment shown in Figs, la, lb, 2 and 3, each magnet of the set of magnets 3 is a neodymium magnet. Neodymium magnets can operate at temperatures up to 230 degrees Celsius, whereas other types of magnets commonly employed in 3D printers cannot operate at temperatures larger than 120 degrees Celsius. Therefore, neodymium magnets extend the operating temperature and durability of the 3D printer 1 as compared to the case wherein other types of magnets were employed. Alternatively, other types of magnets may be utilized for one or more of the magnets of the set of magnets 3 provided that at least one magnet is a neodymium magnet. Alternatively, none of the magnets of the set of magnets 3 may be a neodymium magnet.

[0087] Fig. 4a and Fig. 4b illustrate a side view of an embodiment similar to that in Figs, la, lb, 2 and 3. In Fig. 4a and Fig. 4b, the actuation mechanism 7 is in the printing position and lifting position, respectively. As compared to the embodiment in Figs, la, lb, 2 and 3, the difference is that in the embodiment in Figs. 4a-4b the actuation mechanism 7 is coupled to the detaching mechanism 6 in such a way that the detaching mechanism 6 is moved with the actuation mechanism 7 when the actuation mechanism 7 is moved between the printing position and the lifting position. The carrier platform 2 is supported by supporting members 21, which keep the carrier platform 2 at a fixed distance from the printer floor 17.

[0088] As shown in Fig. 4a, in the printing position of the actuation mechanism 7 the first rod-shaped element 13 and second rod-shaped element 14 have a length 19a and a length 20a, respectively. As shown in Fig. 4b, in the lifting position of the actuation mechanism 7 the first rod-shaped element 13 and second rod-shaped element 14 have a length 19b and a length 20b, respectively. The length 19b and length 20b are larger, respectively, than the length 19a and length 20a. The first rod-shaped element 13 and second rod-shaped element 14 are telescopic. However, alternative detaching elements are conceivable, such as hooks, levers, or gripping stands, configured to abut or engage with the protruding portion 5 in the lifting position of the actuation mechanism 7.

[0089] In any of the embodiments herein disclosed, including any respective variation, the 3D printer 1 may further comprise a processor. In such a case, a computer program product may be executed by the processor. The computer program product comprises instructions which, when the computer program product is executed by the processor, cause the 3D printer to carry out the 3D printing method according to the invention.

[0090] The person skilled in the art realizes that the present invention by no means is limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0091] For example, as a variation of the embodiment in Figs. 4a and 4b, it is feasible that the supporting members 21 are configured to move the carrier platform 21 in relation to the printer floor 17. In such a case, the distance between the detaching mechanism 6 and the flexible sheet 4 is adjustable not only by virtue of the actuation mechanism 7, but also using the supporting members 21, thereby offering an additional degree of freedom. The supporting members 21 may be pneumatic actuators, hydraulic actuators, lead screws, or belts engaging with a system of pulleys.

[0092] As another example, Fig. 5 illustrates a perspective view of an embodiment similar to that disclosed in Figs, la, lb, 2 and 3. In the embodiment shown in Fig. 5, the carrier platform 2 comprises holes 22 through which the first rod-shaped element 13 and second rod-shaped element 14 are configured to pass when the actuation mechanism 7 is in the lifting position. The holes 22 are not part of the carrier platform 2. Therefore, the protruding portion 5 comprises the sections of the flexible sheet 4 which cover the holes 22 when the actuation mechanism 7 is the printing position. The first protruding section 15 and second protruding section 16 are the sections of the protruding portion 5 which, in the lifting position of the actuation mechanism 7, abut the first rod-shaped element 13 and second rodshaped element 14, respectively.

[0093] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS1. A 3D printer (1) for printing an object (OBJ), the 3D printer comprising: a carrier platform (2) configured to be heated to a printing temperature for printing the object (OBJ), the carrier platform (2) comprising a set of one or more magnets (3); a flexible sheet (4) configured to support the object (OBJ), the flexible sheet comprising a protruding portion (5); a detaching mechanism (6); and an actuation mechanism (7) being movable between a printing position and a lifting position, the actuation mechanism (7) being coupled to one of the carrier platform (2) and the detaching mechanism (6) in such a way that the actuation mechanism (7) is configured to move the detaching mechanism (6) with respect to the carrier platform (2) and the flexible sheet (4), or the actuation mechanism (7) is configured to move the carrier platform (2) and the flexible sheet (4) with respect to the detaching mechanism (6) when the actuation mechanism (7) is moved between the printing position and the lifting position; wherein in the printing position of the actuation mechanism (7): the flexible sheet (4) is attached to the carrier platform (2) as a result of a magnetic force applied by the set of magnets (3) on the flexible sheet (4); the protruding portion (5) protrudes from the carrier platform (2); and the detaching mechanism (6) is decoupled from the protruding portion (5) so that any force applied by the detaching mechanism (6) on the protruding portion (5) is insufficient for counteracting the magnetic force; wherein in the lifting position of the actuation mechanism (7): the detaching mechanism (6) is abutting or in engagement with the protruding portion (5) so that a force applied by the detaching mechanism (6) on the protruding portion (5) is sufficient for counteracting the magnetic force and for detaching, at least partially, the flexible sheet (4) from the carrier platform (2), wherein the flexible sheet (4) comprises at least a first edge (9), a second edge (11) and a third edge (12), and the detaching mechanism (6) comprises a first rod-shaped element (13) and a second rod-shaped element (14), the first rod-shaped element (13) and thesecond rod-shaped element (14) being arranged extending perpendicularly to the carrier platform (2), wherein the protruding portion (5) comprises a first protruding section (15) arranged at the second edge (11) of the flexible sheet (4), and a second protruding section (16) arranged at the third edge (12) of the flexible sheet (4), wherein, in the printing position of the actuation mechanism (7), the first rodshaped element is at a distance from, or touches, the first protruding section (15), and the second rod-shaped element (14) is at a distance from, or touches, the second protruding section (16), and wherein, in the lifting position of the actuation mechanism (7), the first rodshaped element (13) is abutting or in engagement with the first protruding section (15), the second rod-shaped element (14) is abutting or in engagement with the second protruding section (16), and each of the first rod-shaped element (13) and the second rod-shaped element (14) apply a force in a direction perpendicular to the carrier platform (2).

2. A 3D printer (1) according to claim 1, wherein the detaching mechanism (6) comprises a temperature sensor (8a, 8b) configured to measure a temperature of the flexible sheet (4) in the lifting position of the actuation mechanism (7).

3. A 3D printer (1) according to any one of claim 1 and 2, wherein the flexible sheet (4) comprises at least a first edge (9), and wherein the flexible sheet (4) is connected to the carrier platform (2) by at least one hinge connection (10) arranged on the first edge (9) of the flexible sheet (4).

4. A 3D printer (1) according to any one of the preceding claims, wherein the first rod-shaped element (13) comprises a first temperature sensor (8a), and the second rodshaped element (14) comprise a second temperature sensor (8b), and wherein the first temperature sensor (8a) and the second temperature sensor (8b) are configured to measure a temperature of the flexible sheet (4) in the lifting position of the actuation mechanism (7).

5. A 3D printer (1) according to any one of the preceding claims, wherein, in the printing position of the actuation mechanism (7), the flexible sheet (4) lies flat on the carrierplatform (2), and wherein, in the lifting position of the actuation mechanism (7), the flexible sheet (4) is curved.

6. A 3D printer (1) according to any one of the above claims, wherein: the 3D printer (1) further comprises a printer floor (17); the first rod-shaped element (13) and the second rod-shaped element(14) are attached to the printer floor (17) and arranged extending perpendicularly to the printer floor (17); and the carrier platform (2) is arranged extending parallelly to the printer floor (17); wherein, in the printing position of the actuation mechanism (7): the carrier platform (2) is spaced apart from the printer floor (17) by a first separation distance (18a); and wherein, in the lifting position of the actuation mechanism (7): the carrier platform (2) is spaced apart from the printer floor (17) by a second separation distance (18b) being smaller than the first separation distance (18a).

7. A 3D printer (1) according to any one of the preceding claims, wherein, in the printing position of the actuation mechanism (7), each of the first rod-shaped element (13) and the second rod-shaped element (14) has a respective first length (19a, 20a); and wherein, in the lifting position of the actuation mechanism (7), each of the first rod-shaped element (13) and the second rod-shaped element (14) has a respective second length (19b, 20b) being larger than the respective first length (19a, 20a).

8. A 3D printer (1) according to any one of the preceding claims, wherein the flexible sheet (4) comprises a ferromagnetic material.

9. A 3D printer (1) according to any one of the preceding claims, wherein the flexible sheet (4) has a thickness in a range of 0.1 mm to 1 mm.

10. A 3D printer (1) according to any one of the preceding claims, wherein the set of magnets (3) is arranged in a regular pattern such that, in the printing position of the actuation mechanism (7), the flexible sheet (4) is flat.

11. A 3D printer (1) according to any one of the preceding claims, wherein at least one of the one or more magnets (3) of the set of magnets (3) is a neodymium magnet.

12. A method for printing an object (OBJ) using the 3D printer (1) according to any one of claims 1 to 11, wherein the method comprises the steps of: a. heating the carrier platform (2) to a printing temperature for printing the object (OBJ); b. bringing the actuation mechanism (7) into the printing position, in which the flexible sheet (4) is attached to the carrier platform (2) as a result of a magnetic force applied by the set of magnets (3) on the flexible sheet (4), and the protruding portion (5) is decoupled from the detaching mechanism (6) so that any force applied by the detaching mechanism (6) on the protruding portion (5) is insufficient for counteracting the magnetic force; c. printing the object (OBJ) by depositing a printing material on the flexible sheet (4); d. bringing the actuation mechanism (7) into the lifting position, in which the detaching mechanism (6) abuts or engages with the protruding portion (5) so that a force applied by the detaching mechanism (6) on the protruding portion (5) is sufficient for counteracting the magnetic force, and for detaching, at least partially, the flexible sheet (4) from the carrier platform (2); e. letting the flexible sheet (4) and the printed object (OBJ) cool to a predetermined temperature; and f. removing the object (OBJ) from the flexible sheet (4).

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