Equipment for additive manufacturing of parts

Abstract

This invention discloses an apparatus (100) for additive manufacturing of components, which facilitates the replacement of components worn during the additive manufacturing process and / or facilitates the use of components made of different materials. To this end, a cartridge (112) having multiple nozzles (110) is provided, which facilitates the automatic switching of one nozzle to another during the manufacturing process. By using a suitable actuator, either only the nozzles (110) can be switched, or the reservoir (108) to which the nozzles (110) are attached can be replaced. When the reservoir (108) is replaced, the piston housed therein can be switched simultaneously.

Description

Technical Field

[0001] The present invention relates to an apparatus for additive manufacturing of components, specifically to additive manufacturing of components by applying liquid material dropwise using a printhead. Background Technology

[0002] Additive manufacturing processes are characterized by high design freedom and tool-free production. Therefore, they are particularly suitable for highly complex individual parts and components that cannot be manufactured using conventional manufacturing processes, or would be prohibitively expensive to produce. In these additive manufacturing processes, workpieces are built in layers or components based on digital models.

[0003] A typical process used to build metal parts is the so-called "material jetting" (MJT) process, in which molten material is printed directly onto a stacking platform by a printhead through one or more individually controlled nozzles.

[0004] In the aforementioned additive manufacturing process, also known as "liquid metal printing" (LMP), nozzles are typically used to generate droplets from a liquid melt, with the nozzle opening being an integral part of the printhead. In the apparatus shown in WO 2020 / 120568 A1, a special nozzle plate is inserted into the printhead and secured to a crucible containing the melt by a friction fit using clamping nuts. Summary of the Invention

[0005] The object of this invention is to provide a method for improving known systems, particularly in terms of increasing the efficiency of manufacturing parts from molten material.

[0006] The nozzles of the aforementioned printhead are typically subject to wear. Therefore, if these components fail during manufacturing, it usually leads to a process interruption, especially if the nozzles are not cleaned online. Following such a process interruption, the nozzle plate or other parts of the printhead containing the nozzle plate must then be replaced. This can be achieved, for example, by using a clamping nut that frictionally and removably connects the nozzle plate to the crucible.

[0007] For manufacturing reasons, the nozzle clamping nut is preferably made of a metallic material. On the other hand, most other components of a commonly used printhead are preferably engineering ceramics, which exhibit low thermal expansion. Since ceramics lack the deformation properties associated with fluid use, a challenge arises regarding the sealing of, for example, the nozzle plate relative to the crucible or a guide sleeve disposed within the crucible, to prevent leakage of the molten melt. This is particularly important because the crucible is subjected to overpressure during startup and the manufacturing process, which promotes droplet formation. Therefore, according to the invention, an elastic portion of the component is provided, such that sufficient clamping force is obtained, for example, of the clamping nut against the ceramic guide sleeve. Furthermore, it is advantageous that the metallic material of the component has a substantially the same coefficient of thermal expansion as the ceramic component. In the present invention, it has been particularly recognized that plastic deformation of the heat-resistant sealing ring can prevent melt leakage at the nozzle plate.

[0008] The nozzle plate itself is a core component for droplet generation and places high demands on the materials used. Further challenges arise from the aforementioned process-related nozzle plate wear. Specifically, for process times of several days, this necessitates in-line cleaning or multiple nozzle plate replacements during the printing process to ensure consistent droplet quality. Therefore, it has been found that in-line cleaning is particularly ineffective in eliminating adhesion within the nozzle orifice, such as adhesion occurring in processes involving magnesium alloys. Furthermore, the nozzle orifice can become contaminated due to mechanical impacts on the nozzle, or may cause damage to the nozzle and droplet separation edges. Therefore, to reduce process downtime, the nozzle plate should be replaced during the process (i.e., when it is hot). The solution according to the invention makes it possible to replace the nozzle plate during the printing process, particularly when the crucible is filled and heated.

[0009] Another understanding that forms the basis of this invention is that, in addition to the aforementioned methods for changing nozzle plates during the manufacturing process, crucible replacement may also be necessary during the deposition process. For example, even with a new nozzle installed, if reproducible droplet quality is not achieved, this may be due to, for example, impurities in the piston guide or excessive slag in the crucible. Furthermore, there is a technical possibility in LMP processes to handle different materials during the deposition process. To avoid using two separate printheads in parallel and to keep the crucible of a single type, a separate crucible should be used for each material or alloy. Moreover, if different printheads with nozzle orifices of different diameters are used, the application rate can be increased, and thus cost-effectiveness or the level of detail in the part can be improved. Therefore, a smaller diameter can be used for a higher level of detail, while a larger diameter can be used to increase the application rate.

[0010] Therefore, it is advantageous to use a separate crucible for each material or alloy. However, this requires changing the crucible during the ongoing process, and also, if necessary, changing the actuator. According to the invention, a crucible changer is provided for this purpose, by means of which a crucible with a nozzle plate can be changed during the ongoing process, and the actuator can also be changed if necessary.

[0011] The nozzle plate described in this article enables a reliable seal relative to the ceramic components of the printhead, and thus prevents melt leakage despite overpressure in the crucible.

[0012] Furthermore, the nozzle plate replacement method of this invention reduces crucible costs and cleaning expenses by using an interchangeable nozzle plate and changing the nozzle orifice diameter during the process. Additionally, replacing the nozzle plate can improve droplet quality.

[0013] Furthermore, the present invention provides a method for performing crucible replacement during the printing process and removing the piston in a simple and automated manner when necessary. Attached Figure Description

[0014] Embodiments and further developments of the present invention will now be described with reference to the accompanying drawings.

[0015] Figure 1 A partial cross-sectional perspective view of the printhead according to the present invention is shown;

[0016] Figure 2 It shows the use of Figure 1 A perspective view of an exemplary nozzle of the printhead shown;

[0017] Figure 3 A top view and two cross-sectional views of a cartridge having multiple nozzles according to the present invention are shown;

[0018] Figure 4 A view of an exemplary apparatus for performing crucible replacement during the process is shown; and

[0019] Figure 5 A schematic diagram of a portion of the printhead and two associated cross-sectional views are shown. Detailed Implementation

[0020] Figure 1 An apparatus 100 for additive manufacturing of parts is shown (see Figure 4An exemplary printhead 102 is described. The printhead 102 includes a base 106 to which a reservoir 108 containing a liquid melt of liquid material 16 is secured. Here, the term "base" should be interpreted and represented broadly, and essentially refers to a portion of the printhead attached to a particular reservoir 108. Specifically, it will be understood by those skilled in the art that an actuator 132 is typically disposed in the base 106, which moves a piston 130 also attached to the base 106, causing the base to eject liquid material 16 from an outlet opening 109 disposed in the reservoir 108. A controller 200 is configured to control the actuator 132. The controller 200 is configured to control the printhead 102 (specifically the actuator 132) to apply liquid material 16 in a known manner.

[0021] For example, piston 130 can be driven and moved axially by actuator 132 in the form of a piezoelectric actuator to discharge liquid melt from outlet opening 109. It is thus understood that, in some embodiments, a guide sleeve (not shown) guiding piston 130 may be provided in outlet opening 109.

[0022] The nozzle 110 is attached to the reservoir 108 at the lower end of the outlet opening 109. As will be explained in more detail below, for example, a component having the nozzle 110 (e.g., a nozzle plate, etc.) can be fastened to the reservoir 108 by a fastening element 119 (such as a clamping nut).

[0023] Figure 2 An exemplary nozzle 110 is shown, which can be fastened to or via the reservoir 108 to the printhead 102. Figure 2 As shown, the nozzle 110 has a nozzle opening 111 formed in the shape of a through hole through the nozzle plate 115. The nozzle plate can be made of, for example, graphite. It should be understood that other materials, such as various metals or alloys thereof, can also be used. In the example shown, the nozzle plate 115 is configured in a substantially circular shape, but it should be understood that the shape of the nozzle plate 115 is not limited to this, and it can have any other shape.

[0024] The nozzle opening 111 is surrounded by a malleable sealing material 117 for sealing against the reservoir 108. Specifically, the sealing material 117 is, for example, a malleable seal branded SIGRAFLEX®. The sealing material 117 is heat-resistant and, in some embodiments, can protrude from the nozzle plate 115 by a predetermined amount, such as 100 to 200 micrometers. In some embodiments, the sealing material 117 may be composed of multiple layers, for example, multiple layers of graphite.

[0025] During operation, the nozzle 110 is detachably secured to the printhead 102 in a first mounting position relative to the base 106. In this respect, as... Figure 1 As shown, fastening to the printhead 102 at the first mounting position specifically means fastening the nozzle 110 to the base 106 of the printhead 102 via the reservoir 108. Thus, the nozzle 110 has a predetermined positional relationship relative to the base 106 corresponding to the first mounting position. Therefore, it should be understood that the relative positional relationship between the base 106 and the nozzle 110 can be appropriately defined using, for example, a suitable reference point on the base 106. For example, the first mounting position can be defined by a distance from the lower side of the base 106 along the longitudinal axis of the piston 130 and a predetermined position in a plane perpendicular to said lower side (e.g., on the longitudinal axis).

[0026] When the nozzle 110 is attached using a fastening element 119 (e.g., a clamping nut), the sealing material 117 plastically deforms, thereby ensuring a desired seal relative to the reservoir 108 or its guide sleeve (not shown). Specifically, in the case where the sealing material 117 is constructed of multiple thin deposits, the melt can diffuse into the material in the transition region, thus forming a barrier. This prevents leakage of the liquid melt, especially even when overpressure is applied. In this respect, the same sealing material 117 can be additionally disposed on the other side of the reservoir 108, relative to... Figure 1 The isolation plate 121 shown seals the reservoir 108.

[0027] During the manufacturing process, it may now be necessary to change the nozzles 110. Therefore, in addition to the printhead 102, the apparatus disclosed herein for additive manufacturing of parts includes a cartridge 112 having a plurality of nozzles 110, each of which can be detachably fastened to the printhead 102 in a first mounting position relative to the base 106. Figure 3 An example of this material box 112 is shown in the figure.

[0028] like Figure 3 As shown, the material box 112 includes a carrier having the plurality of nozzles 110, the carrier being displaceably mounted in the fastening element 119. Figure 3 In the illustrated embodiment, the carrier is formed as an integrated nozzle plate 115, which forms the corresponding nozzle openings 111 of the plurality of nozzles 110. In other words, the carrier, repositionably mounted in the fastening element 119, is formed as a substantially rectangular nozzle plate 115 shape, wherein the plurality of nozzle openings 111 are formed as through holes arranged in a row. Preferably, a sealing material 117 surrounding the corresponding nozzle opening 111 is provided as a single, integral sealing element on the nozzle plate 115, such as... Figure 3 As shown. From Figure 3 It is also evident that when the carrier or nozzle plate 115 is along the fastening element 119 Figure 3When the displacement is made in the direction indicated by the middle arrow, the first nozzle opening or nozzle in nozzle opening 111 or associated nozzle 110 can be moved from the center position of fastening element 119, and the proximal nozzle opening 111 or proximal nozzle 110 can be moved to that position. Therefore, it should be understood that for fastening element 119 fastened to reservoir 108, the first nozzle can be moved from the first mounting position in this manner, and a new nozzle housed in hopper 112 can be moved to the first mounting position. For this purpose, at least one actuator 114, 124 (see...) is provided. Figure 4 At least one actuator is configured to be controlled by controller 200 to move printhead 102 and / or cartridge 112 relative to each other, such that one of the plurality of nozzles 110 moves to a first mounting position.

[0029] For example, at least one actuator 114, 124 can be used to... Figure 3 The right end of the carrier or nozzle plate 115 shown is shifted a predetermined amount to the left, such that a new nozzle 110 is positioned in the first mounting position. Alternatively, the at least one actuator 114, 124 can also be controlled to move the printhead 102, on which a fastening element 119 is attached, such that the right end of the carrier 115 moves against a stop provided thereto, and as the printhead moves further in the direction of the stop, the new nozzle 110 is moved to the first mounting position. However, in both cases, automatic displacement of the carrier 115, and therefore automatic replacement of the nozzle 110, is possible without prolonged process interruptions. Thus, the nozzle can be replaced even when the nozzle plate is at crucible temperature and in an inert gas atmosphere (if applicable). It should be understood that the resistance to displacement of the carrier must be set sufficiently large to eliminate as much undesirable displacement as possible during manufacturing.

[0030] For example, in some embodiments, the fastening element 119 may be slightly loosened before the carrier is displaced to facilitate the displacement. Then, after the displacement, the fastening element 119 is tightened again.

[0031] In the above example, even though the cartridge 112 includes an integral nozzle plate 115 with an integral sealing material 117, it should be understood that the invention is not limited thereto. Therefore, for example, a suitable carrier can be used that can accommodate individual nozzles 110 in a corresponding container (e.g., a recess), each nozzle as... Figure 2 As shown. In this respect, the carrier does not need to be made of the same material as the nozzle plate 115. Furthermore, it should be understood that the substantially rectangular shape of the carrier 115 is not limited to this, and suitable shapes, such as arc segments, can be used, as long as the carrier can be shifted or offset in the correspondingly formed fastening element 119 in the manner described above.

[0032] As mentioned above, during the manufacturing process, it is necessary or expected that the reservoir 108 with nozzle 110 will need to be replaced. This will be referred to below. Figure 4 To explain in more detail.

[0033] like Figure 4 As shown, in some embodiments, the cartridge 112 may include a plurality of receptacles 122, each receptacle configured to accommodate a reservoir 108, the reservoir 108 being removably secured to the base 106 in a second mounting position relative to the base 106 of the printhead 102. Figure 4 In the example shown, the corresponding receptacle 122 is formed as a hollow cylinder, in which a reservoir 108 can be accommodated from above. It should also be understood that the term "second mounting position" should be interpreted broadly and simply indicates a predetermined positional relationship between the reservoir 108 attached to the base 106 and the base 106, which can be suitably defined, for example, by a reference point on the base 106. It should also be understood that when the reservoir 108 is attached to the base in the second mounting position, the nozzle 110 attached to the reservoir 108 is therefore preferably also in the first mounting position. This means that the reservoirs 108 accommodated in the respective receptacles 122 preferably each have a nozzle 110 attached to the respective reservoir such that one of its nozzle openings is in fluid communication with the reservoir's outlet opening 109. Therefore, Figure 4 The illustrated cartridge 112 can also be interpreted as a cartridge having a plurality of nozzles 110, each of which is detachably secured to the printhead in a first mounting position relative to the base 106 (i.e., via the reservoir 108). Therefore, at least one actuator is also controlled to move one of the plurality of nozzles (along with the associated reservoir 108) to the first mounting position. Thus, in addition to facilitating the replacement of the reservoir 108, Figure 4 The illustrated embodiment also features a reference interchange. Figure 3 The effect of nozzle 110 is described.

[0034] The replacement of memory 108 will be discussed in more detail below. Specifically, Figure 4 The controller 200 of the illustrated device 100 is configured to control the at least one actuator 114, 124 such that the empty first reservoir is positioned adjacent to and at a predetermined distance from the first storage container fastened to the base 106. For example, for Figure 4 The device shown has multiple receptacles 122 disposed on multiple arms that extend radially and are pivotable about a pivot axis Z, and can be rotated about the pivot axis Z by an actuator 124 such that the empty receptacle 122 is located below the reservoir 108 attached to the printhead 102.

[0035] Then, at least one actuator 114, 124 is controlled to cause relative movement in the Z direction between the secured reservoir 108 and its housing 122, such that the secured first reservoir is positioned in the first housing. For example, actuator 114 can lower the printhead 102 in the Z direction (and, if applicable, the attached cartridge 112) until the reservoir is positioned in the housing 122. The securing of the first reservoir can then be released in a suitable manner, and the released first reservoir, contained in the first housing, can be moved from the second mounting position to a different position. It should be understood that typically piston 130 (see...) Figure 1 The reservoir protrudes from the base 106. This means that the released reservoir, along with its housing, typically needs to be moved away from the base 106 to allow for a new pivot about the pivot axis Z. Subsequently, the second housing, in which the (new) second reservoir is received, can be moved so that the second reservoir is moved to a second mounting position. It should be understood that, in addition to the pivoting movement, movement in the Z direction toward the base 106 may also be required. Finally, the second reservoir can then be secured to the base 106 in a suitable manner. As described above, since the reservoir 108 is typically provided with a nozzle 110, or in some cases, with... Figure 3 The nozzle box shown can also be interpreted as a nozzle replacement.

[0036] It should be understood that in order to perform the aforementioned replacement of the reservoir 108 in the previous steps, other components surrounding the printhead 102 must first be removed from the reservoir 108. For example, Figure 4 The end tank 126 shown, which has a heater, an inert gas guide, etc., must be moved downwards to expose the reservoir 108.

[0037] Using the system described above, the entire replacement process can be carried out without the need for lengthy cooling phases for individual sub-components. After cooling, the used reservoir can be removed from the crucible changer and cleaned during or at the end of the ongoing printing process.

[0038] When different materials are handled during the manufacturing process, in addition to replacing the reservoir 108 as described above, the piston 130 usually also needs to be replaced. This is especially true when a piezoelectric actuator is used as the actuator 132 (see...). Figure 1 In the case of piston 130, since piston 130 must be preloaded with a limited force relative to the piezoelectric actuator to generate droplets, the system must first depressurize to release piston 130, which will be explained in more detail below.

[0039] Figure 5A schematic diagram of the upper end of piston 130 is shown on the left, which is supported on base 106. Specifically, the upper end of piston 130 is held by a retaining member 137, which is biased against base 106 by piston 130. Thus, a suitable biasing element (e.g., spring 135) is supported on base 106 and biases the retaining member 137, which houses the upper end of piston 130, toward base 106 (upward), for example, against a sleeve (not shown) of actuator 132, which is detachably connected to base 106. Actuator 132 (e.g., piezoelectric actuator) is disposed in base 106 such that its lower end substantially abuts the upper end of piston 130, such that upon actuation, piston 130, together with retaining member 137, moves downward toward outlet opening 109.

[0040] In order to remove the piston by means of a piston engagement device 138 appropriately disposed around or at the piston 130, the piston 130 must first be separated from the actuator 132. For this purpose, a separation device 133 in the form of, for example, an insertion opening is provided in the base 106, by means of which the retaining member 137 can be moved away from the base 106 against bias by inserting a suitable tool. For automatic removal and reinsertion of the piston 130, the controller 200 can be configured to control the piston engagement device 138 (e.g., a conventional gripping element, etc.) to grip the gripped piston 130 and remove it from the retaining member 137 as it moves away from the base 106.

[0041] In one embodiment, the upper end of the piston 130 has at least one radially projecting overhang 140, which is received in a corresponding guide groove 142 of the retaining member 137 and restricts the movement of the piston 130 in its longitudinal and circumferential directions. Therefore, the guide groove 142 is discontinuous in the Z-direction, with its lower end forming a stop. This is in Figure 5 The right side is shown in two sectional views along line AA. Figure 5 In the example shown, three overhangs 140 are provided. Therefore, the upper right side of the figure shows the state in which the overhangs 140 are accommodated in the corresponding guide grooves 142, preventing the piston from moving in the circumferential direction or downward.

[0042] However, after the retaining member and piston 130 have been released using the separation device 133, the piston can be moved in the direction of the base 106 using the piston engagement device 138, and the piston can be rotated about its longitudinal axis by a predetermined angle, for example, 60°, whereby the radially protruding overhang 140 aligns with the corresponding extraction groove 144 in the retaining member 137. Thus, unlike the guide groove 142, the extraction groove 144 is formed through the entire retaining member 137, allowing the properly positioned piston 130 to be removed downward from the retaining member 137 and the base 106.

[0043] It should be understood that Figure 5 The separation device 133 shown in the form of an insertion opening is merely exemplary, and any other mechanism may be used to overcome bias and facilitate the movement of piston 130 in the direction of actuator 132 to facilitate automatic piston replacement.

[0044] It should also be understood that when implementing the combination Figure 4 When replacing the described reservoir 108, the piston replacement described above is particularly advantageous.

[0045] Overall, in the aforementioned equipment and / or methods, all components of the printhead 102 are replaced during the process, as these components are subject to wear and tear, and the use of different materials facilitates more flexible production. Therefore, since parts can be replaced without stopping manufacturing or cooling all components of the printhead 102, the overall efficiency of manufacturing or the manufacturing process can be improved.

[0046] It is explicitly emphasized that, for the purposes of the original invention and for the purpose of limiting the claimed invention, all features disclosed in the specification and / or claims are considered separate and independent of each other, regardless of the combination of features in the embodiments and / or claims. It is explicitly stated that, for the purposes of the original invention and for the purpose of limiting the claimed invention, and particularly as a limitation on the scope indications, all scope indications or unit group indications disclose any possible intermediate values ​​or unit subgroups.

Claims

1. An apparatus for additive manufacturing of parts, comprising: A printhead configured to apply liquid material, wherein the printhead includes a base; A controller configured to control the printhead to apply the liquid material; A cartridge having multiple nozzles, each nozzle being detachably secured to the printhead in a first mounting position relative to the base; and A first reservoir, configured to contain the liquid material, and capable of being detachably fastened to the base in a second mounting position relative to the base; A piston, attached to the base and configured to eject the liquid material from an outlet opening defined in the first reservoir; A retaining member that holds the upper end of the piston is movably mounted on the base, wherein the retaining member is biased against the base by the piston; A separation device configured to move the holding member against the bias voltage; and A piston engagement device configured to engage with the piston when the first reservoir is released; At least one actuator, the at least one actuator being configured to be controlled by the controller to move the printhead and / or the cartridge relative to each other, such that one of the plurality of nozzles moves to the first mounting position; The controller is configured to control the piston engagement device to remove the gripped piston from the retaining member as the retaining member moves away from the base.

2. The device according to claim 1, in, Each nozzle is removably fastened to the first reservoir in the first mounting position such that the nozzle opening of the nozzle is in fluid communication with an outlet opening formed in the reservoir, and includes a nozzle plate forming the nozzle opening and a malleable sealing material surrounding the nozzle opening for sealing against the first reservoir.

3. The device according to claim 2, wherein, The sealing material is constructed of multiple layers and / or protrudes a predetermined amount from the nozzle plate.

4. The device according to claim 2 or 3, further comprising a fastening element configured to fasten the cartridge to the first reservoir. in, The material box includes a carrier having the plurality of nozzles, the carrier being repositionably mounted in the fastening element.

5. The device according to claim 4, wherein, The carrier is formed as a one-piece nozzle plate, and the one-piece nozzle plate forms the corresponding nozzle openings of the plurality of nozzles. The sealing material is disposed on the nozzle plate as a single, integral sealing element surrounding the corresponding nozzle opening.

6. The device according to claim 5, wherein, The controller is configured to control the at least one actuator such that the at least one actuator directly or indirectly displaces the carrier in the fastening element, causing a first nozzle of the plurality of nozzles to move from the first mounting position, and a second nozzle of the plurality of nozzles to move to the first mounting position.

7. The device according to claim 1, in, The hopper includes multiple receptacles, each configured to accommodate a second reservoir. Each of the plurality of nozzles is disposed on a second reservoir housed in one of the reservoirs, such that the nozzle opening of the nozzle is in fluid communication with an outlet opening formed in the reservoir.

8. The device according to claim 7, wherein, The controller is configured to control the at least one actuator to perform the following operations: Move the empty first container to a position adjacent to and at a predetermined distance from the first reservoir fastened to the base. The fastened first reservoir and the first housing are moved relative to each other so that the fastened first reservoir is located in the first housing. Release the fastener of the first reservoir. The first reservoir, housed in the first container, is moved to a position different from the second mounting position. Move the second housing containing the second reservoir so that the second reservoir is positioned at the second mounting position; and Secure the second reservoir to the base.

9. The device according to claim 7, wherein, The plurality of receptacles are configured to pivot about a pivot axis, and a first actuator is configured to cause the plurality of receptacles to pivot about the pivot axis.

10. The device of claim 8, further comprising a cover capable of being fastened to the base for covering and heating the first reservoir fastened at the second mounting position. in, The third actuator is configured to move the released cover away from the base to expose the first reservoir.

11. The device according to claim 8, wherein, The first reservoir and the second reservoir differ in at least one aspect: the diameter of the liquid material contained therein or the nozzle opening of the associated nozzle.

12. The device according to any one of claims 1 to 3, wherein, The upper end of the piston includes at least one radially projecting overhang, which is received in a corresponding guide groove of the retaining member and restricts the movement of the piston in its longitudinal direction. The controller is configured to control the piston engagement device to rotate the piston about its longitudinal axis by a predetermined angle, and after the piston moves toward the base, it is configured to move the rotated piston away from the base to remove it from the retaining member.

13. The device according to any one of claims 1 to 3, wherein, The separation device includes at least one insertion opening formed in the base, through which the separation device can be inserted between the base and the retaining member to separate them from each other.

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