Non-contact removal of blockages from metal jet printhead nozzles

Abstract

A method for printing 3D parts includes the step of lowering the temperature of the build material in the nozzle of a 3D printer to below the melting point of the build material, thereby transitioning the build material in the nozzle from a liquid state to a solid state. The method also includes the step of raising the temperature of the build material in the nozzle to above the melting point of the build material, thereby transitioning the build material in the nozzle from a solid state to a sludge state. The blockage and the sludge-state build material are then ejected from the nozzle.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the priority of U.S. Patent Application No. 18 / 307352, filed on April 26, 2023, which is hereby incorporated by reference herein.

[0002] This disclosure relates generally to three - dimensional (3D) printing, and more specifically to systems and methods for removing obstructions from a metal injection printhead nozzle without physically contacting the nozzle.

Background Art

[0003] When printing with a molten metal forming material using a 3D metal printer, there are many problems. One of those problems is maintaining the nozzle without obstructions. An obstruction refers to a deposit of material inside and / or around the holes of the nozzle. For example, an obstruction may be or may include a circular deposit of metal oxide on the inner surface of the nozzle that defines the nozzle holes, which reduces the effective diameter of the nozzle holes.

[0004] Improvements have been made to 3D metal printers to minimize obstructions, but obstructions are still formed to some extent around the nozzle holes. The deposited obstructions can cause many jetting problems, such as a decrease in droplet size and / or droplet mass, satellites (e.g., tiny droplets at multiple angles in many cases), excessive meniscus action of the molten metal in the nozzle holes, and overall jetting instability. Some mitigation measures have been used in attempts to remove obstructions from the nozzle, but all of the conventional mitigation measures involve mechanical contact / intervention (e.g., scraping, probe methods, etc.) to remove the obstructions. Since mechanical intervention can be difficult and operator - dependent, it may require an automated solution that adds cost and complexity to the 3D metal printer.

Summary of the Invention

[0005] The following is a brief overview to provide a basic understanding of some aspects of one or more embodiments of this teaching. This overview is neither a comprehensive overview nor identifies any important or definitive elements of this teaching, nor does it define the scope of this disclosure. On the contrary, its primary purpose is simply to present one or more concepts in a concise form as a prelude to the detailed explanations that follow.

[0006] A method for printing 3D parts is disclosed. The method includes the step of lowering the temperature of the build material in the nozzle of a 3D printer to below the melting point of the build material, thereby transitioning the build material in the nozzle from a liquid state to a solid state. The method also includes the step of raising the temperature of the build material in the nozzle to above the melting point of the build material, thereby transitioning the build material in the nozzle from a solid state to a sludge state. The blockage and the sludge-state build material are ejected from the nozzle.

[0007] A method for removing blockages from a 3D printer nozzle is also disclosed. The method includes the step of determining that blockages are present in the nozzle. The blockages are substantially annular rings containing metal oxides adhering to the inner surface of the nozzle, reducing the effective diameter of the hole through the nozzle. The method also includes the step of pausing the generation of jet pulses to stop droplets of the build material from being ejected from the nozzle. The build material includes metals. The method also includes the step of releasing the nozzle from the build plate. The method also includes the step of lowering the temperature of the build material in the 3D printer to cause a portion of the build material in the nozzle to transition from a liquid state to a solid state within the nozzle by bringing the build material below its melting point. The method also includes the step of resuming the generation of jet pulses to generate heat in the nozzle to at least partially melt the build material within the nozzle so that the build material transitions from a solid state to a sludge state within the nozzle. The jet pulses eject both the blockages and the sludge-state build material from the nozzle, thereby increasing the effective diameter of the hole through the nozzle. The method also includes the step of using a heating element to raise the temperature of the build material inside the 3D printer to a liquid state in the nozzle. The temperature is raised after blockages and sludge-like build material are ejected from the nozzle. The method also includes the step of realigning the nozzle and build plate after the build material has been heated. The method also includes the step of printing a 3D part on the build plate with the build material once the nozzle and build plate have been realigned.

[0008] A method for printing 3D parts is also disclosed. The method includes the step of using electromagnetic force to extrude a metal alloy from the nozzle of a 3D printer. The metal alloy cools and solidifies after extrusion to form a 3D part. The method also includes the step of determining that an obstruction is present in the nozzle. The method also includes the step of lowering the temperature of the metal alloy in the nozzle to below the melting point of the metal alloy, thereby transitioning the metal alloy in the nozzle from a liquid state to a solid state. The method also includes the step of raising the temperature of the metal alloy in the nozzle to above the melting point of the metal alloy, thereby transitioning the metal alloy in the nozzle from a solid state to a sludge state. The obstruction and the sludge-state metal alloy are extruded from the nozzle.

[0009] A 3D printer is also disclosed. The 3D printer includes a nozzle configured to eject multiple droplets of a build material. The 3D printer also includes a computing system configured to perform an operation. This operation includes lowering the temperature of the build material in the nozzle to below the melting point of the build material, thereby transitioning the build material in the nozzle from a liquid state to a solid state. The operation also includes raising the temperature of the build material in the nozzle above the melting point of the build material, thereby transitioning the build material in the nozzle from a solid state to a sludge state, resulting in the ejection of blockages and sludge-state build material from the nozzle.

[0010] A method for controlling the viscosity of an injector in an injection device is disclosed. The method includes the step of introducing the injector into the injection device. The injector flows through a channel in the injection device. The channel includes an upstream portion and a downstream portion. The method also includes the step of increasing the maximum viscosity of the injector in the downstream portion of the channel to at least 25% higher than the viscosity of the injector in the upstream portion of the channel.

[0011] In other embodiments, the method includes the step of introducing a printing material into a 3D printer. The printing material flows through a channel within the 3D printer. The channel includes an upstream portion and a downstream portion. The method also includes the step of increasing the viscosity of the printing material in the downstream portion of the channel, thereby increasing the solids content of the printing material in the downstream portion of the channel to more than about 1%.

[0012] In other embodiments, the method includes the step of introducing a material into a 3D printer. The material flows through a channel within the 3D printer. The channel includes an upstream portion and a downstream portion. The method also includes the step of lowering the temperature of the material in the downstream portion of the channel until the temperature of the downstream portion of the channel is above the solidus temperature of the material and below the liquidus temperature of the material. [Brief explanation of the drawing]

[0013] [Figure 1] A schematic cross-sectional side view of the 3D printer according to this embodiment is shown. [Figure 2A] An image showing a nozzle opening of a 3D printer with an obstruction, according to an embodiment, is shown. [Figure 2B] The image shows a nozzle opening without any obstruction (for example, after the obstruction has been removed) according to the embodiment. [Figure 3] The graphs shown illustrate (1) the diameter of the nozzle opening as a function of time during printing and (2) the mass of the droplet as a function of time during printing, according to the embodiment. [Figure 4] A flowchart illustrating a method for removing blockages from a 3D printer nozzle according to an embodiment is shown. [Figure 5] A schematic cross-sectional side view of another 3D printer according to this embodiment is shown. [Figure 6] A schematic cross-sectional side view of a portion of another (e.g., inkjet) printer according to another embodiment is shown. [Figure 7] A flowchart of a method for controlling the viscosity of the molding material in a 3D printer according to this embodiment is shown. [Modes for carrying out the invention]

[0014] The accompanying drawings incorporated into and constituting parts thereof in this specification illustrate embodiments of this teaching and, together with a detailed description, contribute to illustrating the principles of this disclosure.

[0015] Exemplary embodiments of this instruction are referenced herein in detail, examples of which are shown in the accompanying drawings. Where possible, the same reference numerals are used throughout the drawings to refer to identical, similar, or identical parts.

[0016] Prevention / removal of obstructions This disclosure includes a 3D printer and a method configured to remove blockages from within a 3D printer nozzle without physically contacting the nozzle (e.g., by scraping, probing, etc.). This method can be implemented with minimal interruption to the printing process and without additional hardware requirements.

[0017] Figure 1 shows a schematic cross-sectional side view of a 3D printer 100 according to an embodiment. The 3D printer 100 is or may include a magnetohydrodynamic (MHD) printer, a piezoelectric printer, etc. The 3D printer 100 may include an ejector (also called a pump) 110. As used herein, the ejector 110 is a structure that can be selectively operated to eject the molding material 120 from a nozzle 114 of the ejector 110. As used herein, the nozzle 114 is a physical structure from which the molding material 120 begins to be ejected.

[0018] The ejector 110 may define one or more reservoirs 112. One ejector reservoir is shown in Figure 1. In other embodiments, the ejector 110 may include two or more reservoirs, including at least a first (e.g., upper) reservoir and a second (e.g., lower) reservoir. In this embodiment, the portion of the ejector 110 defining the upper reservoir may be made of or contain a ceramic material, and the portion of the ejector 110 defining the lower reservoir may be made of or contain a graphite material.

[0019] The ejector reservoir 112 is configured to receive and / or store the shaping material 120 to be ejected from the nozzle 114. The shaping material 120 can be or include metals (e.g., pure metals or alloys), polymers, ceramics, inks, etc. In one embodiment, the shaping material 120 can be greater than about 50%, greater than 60%, greater than 70%, greater than 80%, greater than 90% or about 100% metal (e.g., by volume and / or mass). For example, the shaping material 120 can be or include a wound aluminum wire (e.g., 6061 aluminum). In other embodiments, the shaping material 120 can be or include copper or other metals.

[0020] The 3D printer 100 can also include one or more heating elements 130. The heating element 130 is configured to melt the shaping material 120 within the ejector reservoir 112, thereby converting the shaping material 120 from a solid state to a liquid (e.g., molten) state within the ejector reservoir 112.

[0021] The 3D printer 100 can also include a power source 132 and one or more metal coils 134. The metal coil 134 is at least partially wound around the ejector 110 and / or the heating element 130. The power source 132 can be configured to be coupled to and supply power to the coil 134. In one embodiment, the power source 132 can be configured to supply a step function direct current (DC) voltage profile (e.g., a voltage pulse or an ejection pulse) that generates an increasing magnetic field to the coil 134. The increasing magnetic field can create an electromagnetic force and / or an electromotive force within the ejector 110 and an induced current within the liquid shaping material 120. The magnetic field and the induced current within the liquid shaping material 120 can generate a radially inward force known as the Lorentz force on the liquid shaping material 120. The Lorentz force creates a pressure at the inlet of the nozzle 114 of the ejector 110. This pressure causes the liquid shaping material 120 to be ejected through and / or discharged from the nozzle 114 in the form of one or more droplets 122.

[0022] The 3D printer 100 may also include a modeling plate (also referred to as a substrate) 140 positioned below the nozzle 114. The droplets 122 are ejected from the nozzle 114 and may then land on the modeling plate 140 where they can cool and solidify to form a first (e.g., lower) layer. Additional droplets 122 may be ejected to form layers on top of the layer that will ultimately form the 3D part 124.

[0023] The 3D printer 100 may also include a clog detection device 150. In one embodiment, the clog detection device 150 may be or include a camera or (e.g., laser) scanner configured to capture a feed (e.g., video and / or image) of the nozzle 114, the droplets 122, the 3D part 124, or a combination thereof. In one example, the camera may be configured to capture a feed of the inner surface (e.g., inner diameter) of the nozzle 114 where a clog may be shown. The size and / or shape of the clog may be identified based on the feed. The effective diameter of the nozzle hole may also be identified based on the feed. In another example, the camera may be configured to capture a feed of the droplets 122 as they are falling. More specifically, the feed will show the droplets 122 after they are ejected from the nozzle 114 and before they land on the modeling plate 140. The size, shape, mass, and / or direction of the droplets 122 may be identified based on the feed.

[0024] In other embodiments, the clog detection device 150 may be or include a sensor configured to measure the height of the 3D part 124 along the Z-axis (i.e., z-height). The most recent height measurement may be compared to a previous height measurement. If the most recent height and / or change in height is less than a predetermined height threshold, it may be determined that the mass of the droplets 122 has decreased below a predetermined droplet mass threshold. This may indicate that a clog is present within the nozzle hole.

[0025] In yet another embodiment, the blockage detection device 150 may be configured to measure the amount and / or rate (i.e., input) of the build material (e.g., aluminum wire) 120 being supplied to the ejector 110 using a wire feed encoder. The wire diameter is known to be within tolerance. This, combined with the known density of the build material 120, can be used to determine the mass of build material 120 being supplied into the head per unit time. When averaged over a period (e.g., one minute), assuming that the reservoir level control maintains the reservoir height at a steady value, the input should be very close to the amount of build material 120 being ejected over that same period. Dividing this by the number of droplets ejected during that same period yields the average droplet mass. If this mass decreases significantly below a predetermined input / output threshold for a longer period (e.g., one minute), the blockage detection device 150 may determine that the mass of the droplet 122 has decreased below a predetermined droplet mass threshold. This indicates that an obstruction is present inside the nozzle opening.

[0026] In yet another embodiment, the blockage detection device 150 may be configured to pause printing and eject and weigh a known number of droplets 122 at predetermined intervals (e.g., every 10 minutes). This may be performed between print jobs, or alternatively. The measured weight may be compared to a previous measured weight. It may be determined that the mass of the droplet 122 has decreased to below a predetermined droplet mass threshold based on the comparison and / or the most recent weight (e.g., below a predetermined weight threshold). This would indicate that a blockage is present in the nozzle hole.

[0027] In yet another embodiment, the blockage detection device 150 may be configured to cause the 3D printer 100 to print a pillar (i.e., a thin, vertical 3D part) and measure the height of the pillar. The measured height may be compared to a previously measured height. Then, depending on the comparison and / or the latest height, it may be determined that the mass of the droplet 122 has decreased to below a predetermined droplet mass threshold (e.g., below a predetermined height threshold). This would indicate that a blockage is present in the nozzle hole.

[0028] In the embodiment, the obstruction detection device 150 and / or operator may determine that the droplet mass is below a predetermined droplet mass threshold by confirming and / or detecting the presence of a satellite that was not previously present, indicating that an obstruction is present in the nozzle 114. This may appear as dust on and / or around the 3D part 124. It may also appear as small droplets (e.g., less than 10% of the intended droplet size), which can be detected by the human eye, a camera, or a stroboscope.

[0029] The blockage may form on one side of the nozzle opening and interfere with the direction of the droplet 122 stream. In other embodiments, the blockage detection device 150 and / or operator may determine that the blockage is present in the nozzle 114 by determining that the stream of droplet 122 is ejected from the nozzle 114 at an angle greater than a predetermined angular threshold (e.g., 5 degrees) compared to the direct downward direction.

[0030] The blockage can also affect the print quality of the 3D part 124. Therefore, in other embodiments, the blockage detection device 150 and / or the operator may determine that a blockage is present in the nozzle 114 by confirming / determining that the spray quality and / or print quality has deteriorated and / or that the droplet velocity is inconsistent. This can be confirmed by a strobe and / or by the print quality of the 3D part 124 falling below a predetermined quality threshold.

[0031] The 3D printer 100 may also include a computing system 160. As described below, the computing system 160 may contribute to preventing blockages and / or removing blockages from the nozzle opening to increase its effective diameter by performing at least a portion of the methods described below.

[0032] Figure 2A shows an image captured by the blockage detection device 150 according to the embodiment, showing the nozzle hole containing the blockage. Figure 2A was taken before the sludge injection process was performed, as described below. Due to the presence of the blockage in the nozzle hole, the effective cross-sectional length (e.g., diameter) of the nozzle hole is 389 micrometers (μm).

[0033] Figure 2B shows an image captured by the blockage detection device 150 according to the embodiment, showing a nozzle hole free of blockages. Figure 2B is captured after the sludge injection process has been performed to remove the blockages. After the blockages are removed, the effective cross-sectional length (e.g., diameter) of the hole is 474 μm.

[0034] Figure 3 shows graphs illustrating (1) the diameter of the nozzle opening over time during printing and (2) the mass of the droplets 122 over time during printing according to an embodiment. As can be seen from the graphs, the diameter and mass may decrease over time due to the gradual accumulation of blockage material in the nozzle 114. In this particular example, during the first period of printing (e.g., from 0 minutes to about 140 minutes), the diameter decreases from about 480 μm to about 390 μm, and the droplet mass decreases from about 1.7 g per 10,000 droplets to about 1.35 g per 10,000 droplets. After the first period, a first sludge spraying treatment is performed to remove the blockage material. This increases the diameter again to about 480 μm and the droplet mass again to about 1.65 g per 10,000 droplets. Subsequently, during the second printing period (e.g., from 142 minutes to approximately 240 minutes), the diameter decreases from approximately 480 μm to 410 μm, and the droplet mass decreases from approximately 1.65 g per 10,000 droplets to approximately 1.45 g per 10,000 droplets. After the second period, a second sludge spraying treatment is performed to remove blockages. This increases the diameter again to approximately 470 μm and increases the droplet mass. This treatment can be repeated to help maintain the diameter above a predetermined diameter threshold and / or maintain the droplet mass above a predetermined droplet mass threshold.

[0035] Figure 4 shows a flowchart of a method 400 for removing blockages from the nozzle 114 of a 3D printer 100 according to an embodiment. One or more steps of method 400 may be performed by the 3D printer 100 (e.g., computing system 160). An order for describing method 400 is given below, but one or more steps of method 400 may be performed in a different order, repeated, combined, or omitted.

[0036] Method 400 may include the step in 410 of determining that an obstruction is present in the nozzle 114 of the 3D printer 100. In one embodiment, the step of determining the presence of an obstruction may include the step in 412 of taking in the feed using an obstruction detection device 150.

[0037] The step of determining the presence of an obstruction may also include, in 414, the step of determining the diameter of the nozzle 114 and / or the size of the droplet 122. The diameter and / or size may be determined by the computing system 160 based on the feed. The diameter is or may include the effective diameter. The effective diameter may mean the inner diameter of the annular obstruction in the nozzle 114. Alternatively, the effective diameter may mean the (e.g., minimum) diameter of the hole in the nozzle 114 through which the molding material 120 flows. The droplet size may mean mass, volume, shape, diameter / size, or a combination thereof.

[0038] The step of determining the presence of an obstruction may also include, in 416, the step of comparing the diameter and / or size to a predetermined threshold. The comparison may be performed using a computing system 160. In one example, the predetermined nozzle diameter threshold may be about 450 μm to about 470 μm, about 430 μm to about 450 μm, about 410 μm to about 430 μm, or about 390 μm to about 410 μm. In one example, the predetermined droplet size threshold may be about 1.6 g to about 1.7 g per 10,000 droplets, about 1.5 g to about 1.6 g per 10,000 droplets, about 1.4 g to about 1.5 g per 10,000 droplets, or about 1.3 g to about 1.4 g per 10,000 droplets.

[0039] Obstructions may be determined to be present based on comparison. In one example, an obstruction may be determined to be present (and / or of a specific size) depending on whether the measured / identified nozzle diameter is below a predetermined diameter threshold. In another example, an obstruction may be determined to be present (and / or of a specific size) depending on whether the measured / identified droplet size is below a predetermined droplet size threshold. In other embodiments, the step of determining the presence of an obstruction may be omitted from method 400, and the following steps may be performed as precautions.

[0040] Method 400 may also include a step in 420 of pausing the generation of injection pulses. In other words, the injection pulses generated by the power supply 132 and transmitted to the coil 134 may be stopped. This would prevent the droplets 122 from being ejected from the nozzle 114.

[0041] Method 400 may also include the step of disaligning the nozzle 114 and the build plate 140 in 430. The nozzle 114 and the build plate 140 may be disaligned in response to a determination that an obstruction is present inside the nozzle 114. The nozzle 114 and the build plate 140 may be disaligned while the injection pulse is paused so that droplets 122 are not ejected from the nozzle 114.

[0042] The nozzle 114 and build plate 140 can be de-aligned so as not to affect the 3D part 124 being printed, and so as not to allow subsequent droplets 122 ejected from the nozzle 114 (as described below) to land on the build plate 140 and / or the 3D part 124. In one example, the nozzle 114 may be moved vertically, and the build plate 140 may be moved horizontally (for example, simultaneously). In another example, the nozzle 114 may be moved so as not to be positioned on the build plate 140 and / or the 3D part 124 (and the build plate 140 may remain stationary). Conversely, the nozzle 114 may be positioned on a waste liquid tank configured to receive subsequent droplets 122. In another example, the build plate 140 may be moved so as not to be positioned on the nozzle 114 and / or the 3D part 124 (and the nozzle 114 may remain stationary). Subsequently, the waste liquid tank is positioned below the nozzle 114 to receive subsequent droplets 122. In yet another embodiment, the waste liquid tank may be positioned below the nozzle 114 and / or above the build plate 140, rather than disaligning the nozzle 114 and the build plate 140.

[0043] Method 400 may also include the step of lowering the temperature of the build material 120 in the 3D printer 100 in 440. The temperature of the build material 120 in the ejector reservoir 112 and / or nozzle 114 may initially be above the melting point of the build material (e.g., aluminum) 120 during printing so that the build material 120 is in a liquid (e.g., molten) state in the ejector reservoir 112 and nozzle 114. The melting point of aluminum is about 660°C. In one example, the temperature of the build material 120 in the ejector reservoir 112 may initially be about 825°C, and the temperature of the build material 120 in the nozzle 114 may initially be about 700°C. The temperature of the build material 120 in the nozzle 114 may be lower than that in the ejector reservoir 112 because the ejector reservoir 112 is further away from the heating element 130 (e.g., downstream).

[0044] Depending on whether an obstruction is detected (in 410), whether the nozzle 114 and / or build plate 140 moves (in 420), whether the alignment is released (in 430), or a combination thereof, the temperature of the build material 120 inside the 3D printer 100 will be reduced. The temperature may be reduced while no ejection pulses are being generated so that droplets 122 are not ejected from the nozzle 114. The step of reducing the temperature may be achieved by reducing the amount of heat introduced into the ejector 110, ejector reservoir 112 and / or build material 120 by the heating element 130. In other embodiments, the temperature may be reduced using a cooler.

[0045] The temperature may be reduced until the build material 120 in the nozzle 114 is below its melting point. Continuing the above example, the temperature of the build material 120 in the ejector reservoir 112 is reduced to approximately 700°C (e.g., above its melting point), and the temperature of the build material 120 in the nozzle 114 is reduced to approximately 600°C (e.g., below its melting point). This allows the build material 120 in the nozzle 114 to transition from a liquid state to a solid state (i.e., to solidify). The solidified build material 120 can adhere to the blockage in the nozzle 114, forming a single plug.

[0046] This step (i.e., the step of lowering the temperature) can be performed over a predetermined length of time. For example, the predetermined length of time could be about 1 second to about 10 seconds, about 10 seconds to about 30 seconds, about 30 seconds to about 1 minute, about 1 minute to about 2 minutes, or about 2 minutes to about 5 minutes. As should be understood, the predetermined length of time may depend on the amount of heat introduced into and / or removed from the material 120 in the 3D printer 100. The predetermined length of time may also depend on the temperature to which the material 120 is cooled. Therefore, the greater the temperature decrease, the faster the material 120 solidifies at least partially, and the faster this step can be performed / completed.

[0047] Method 400 may also include the step of generating (or resuming generating) an ejection pulse in 450. The ejection pulse may be generated when the nozzle 114 is not positioned on the build plate 140 and / or the 3D part 124. The ejection pulse may be generated while the temperature is being cooled (for example, when the build material 120 in the nozzle 114 is below its melting point and / or at least partially solidified therein). In one example, the ejection pulse may be generated when the build material 120 in the nozzle 114 is completely solid.

[0048] The power supply 132 generates an injection pulse and transmits it to the coil 134, which can generate a force that causes the droplet 122 to be ejected from the nozzle 114. As the build material 120 solidifies at least partially within the nozzle 114, the droplet 122 may or may not be ejected from the nozzle 114 over a predetermined period of time. Therefore, for a predetermined period of time after the injection pulse is restarted, neither the blockage nor the build material 120 may be ejected from the nozzle 114.

[0049] On the other hand, the injection pulse may generate heat within the nozzle 114. Therefore, even if nothing is ejected for a predetermined length of time after the injection pulse is restarted, the injection pulse can raise the temperature of the molding material 120 within the nozzle 114 until the molding material 120 rises above its melting point again. As a result, the molding material 120 within the nozzle 114 may at least partially melt and transition from a solid state to a sludge state (e.g., partially solid and partially liquid). Once the molding material 120 is in a sludge state (e.g., after a predetermined length of time), it can be ejected from the nozzle 114. The predetermined length of time may be about 1 second to about 10 seconds, about 10 seconds to about 30 seconds, about 30 seconds to about 1 minute, about 1 minute to about 3 minutes, or longer. When the sludge-state molding material 120 is ejected, it expels the blockage from the nozzle 114 along with it, thereby removing it from the nozzle 114. This is sometimes called sludge ejection. As a result, the obstruction can be removed without physical contact such as scraping or probe methods.

[0050] In one embodiment, the generation of injection pulses may not generate enough heat to initiate the melting of the solidified (e.g., condensed) 3D material 120 inside the nozzle 114. This can occur, for example, if the 3D printer 100 is driven by a piezoelectric device rather than an MHD device. In this embodiment, instead of, or in addition to, generating injection pulses to generate heat, other heaters may be positioned at least partially around the nozzle 114 and configured to heat and melt the 3D material 120 inside it. Then, as described above, as the 3D material 120 transitions to a sludge state, it can be ejected from the nozzle 114 and expel any blockages along with it.

[0051] Method 400 may also include, in 460, a step of raising the temperature of the build material 120 in the 3D printer 100. The temperature will be raised before (e.g., restarted) an ejection pulse is generated, at the same time, or afterward. For example, the temperature will be raised before (e.g., simultaneously with) the ejection of sludge-like build material 120 and / or blockages from the nozzle 114. The temperature may be raised using a heating element 130 (e.g., around the ejector 110). The temperature will be raised back to an initial level (e.g., about 825°C in the ejector reservoir 112 and about 700°C in the nozzle 114).

[0052] Method 400 may also include, in 470, the step of generating additional jet pulses (or continuing to generate jet pulses). Additional jet pulses may be generated after sludge-like material 120 and / or blockages have been ejected from the nozzle 114. Additional jet pulses may cause multiple droplets 122 to be ejected from the nozzle 114 and fall into the waste liquid tank. These droplets 122 may be analyzed (e.g., by a blockage detection device 150 and / or a computing system 160) to determine / confirm that the 3D printer 100 has fully re-established a steady state. In other words, the droplets 122 may be analyzed to determine / confirm that the droplets 122 have a predetermined shape, size, mass, ejection frequency, direction or combination thereof.

[0053] Method 400 may also include the step of repositioning the nozzle 114 and the build plate 140 in 480. The nozzle 114 and the build plate 140 may be repositioned in response to the determination / confirmation that sludge-like build material 120 and / or blockages have been ejected from the nozzle 114, the temperature of the build material 120 has risen, and the droplets 122 have a predetermined shape, size, mass, ejection frequency, direction, or combination thereof. The nozzle 114 and the build plate 140 may be repositioned so that subsequent droplets 122 ejected from the nozzle 114 land on the build plate 140 and / or the 3D part 124. In one example, the nozzle 114 may be moved so that the nozzle 114 is positioned on the build plate 140 and / or the 3D part 124 (while the build plate 140 remains stationary). In other examples, the build plate 140 may be moved so that the nozzle 114 is positioned on the build plate 140 and / or the 3D part 124 (and the nozzle 114 may remain stationary).

[0054] Method 400 may also include the step of printing a 3D part 124 in 490. The 3D part 124 may be printed after the sludge-like build material 120 and blockages have been ejected from the nozzle 114 (or printing may be resumed), and the nozzle 114 and build plate 140 are repositioned. The step of printing the 3D part 124 may include the step of generating additional pulses to eject a plurality of droplets 122 from the nozzle 114. The droplets 122 land on the build plate 140 and / or on a previously deposited layer of the 3D part 124, where they may cool and solidify to form a portion of the 3D part 124.

[0055] The method then loops back to step 410, where it can be determined whether or not an obstruction is present in the nozzle 114 of the 3D printer 100. This is shown in Figure 3. In one embodiment, this determination may be made after a predetermined length of time has elapsed since the sludge-like build material 120 and the obstruction were ejected from the nozzle 114, the nozzle 114 and the build plate 140 were repositioned, the 3D part 124 was printed, or a combination thereof. In another embodiment, this determination may be made after a predetermined amount of build material 120 has been used and / or after a predetermined number of droplets 122 have been ejected.

[0056] In the embodiment, a decrease in droplet mass may occur after sludge injection (for example, if the droplet mass had previously flowed abnormally high compared to the standard setting). The droplet mass may then stabilize after sludge injection, returning to a more normal range. Abnormally high droplet mass may be due to bubbles and / or non-wet surfaces within the nozzle 114. The condensation / melting cycle may contribute to the removal of bubbles and / or non-wet areas.

[0057] Method 400 may be used as a preventative measure. In one example, sludge spraying may be performed after the initial loading of the 3D printer 100. In another example, sludge spraying may be performed before the 3D part 124 is fabricated. In another embodiment, sludge spraying may be performed after a predetermined amount of fabrication material 120 has been ejected and / or after a predetermined length of printing time. For example, sludge spraying may be performed before printing the first 3D part, between smaller 3D parts / print jobs, and / or after a predetermined number of spray cycles for larger 3D parts.

[0058] Viscosity fluctuations Figure 5 shows a schematic cross-sectional side view of another 3D printer 500 according to the embodiment. The 3D printer 500 may be similar to printer 100 except for the differences described below. For example, the 3D printer 500 may include a cooling device 520. In one example, the cooling device 520 may be or include a cooling faceplate. For example, the cooling device 520 may include a piece of metal (e.g., copper) that contacts the nozzle 114 in the form of a faceplate. Other effective cooling devices 520 may include or include any liquid cooling by forcing a coolant to flow through an internal channel around the nozzle 114. Other devices / methods such as heat sinks, forced ventilation, etc., or combinations thereof may also be used.

[0059] The cooling device 520 may be positioned at least partially around a portion of the 3D printer 500 and configured to lower (i.e., cool) the temperature of the nozzle 114 and / or the build material 120. In the illustrated embodiment, the cooling device 520 may be positioned at least partially around the nozzle 114 and configured to lower the temperature of the build material 120 inside it. In another embodiment, the cooling device 520 may be positioned vertically between the nozzle 114 and the 3D part 124 or build plate 140 and configured to lower the temperature of falling droplets 122. In yet another embodiment, the cooling device 520 may be positioned at least partially around the 3D part 124 and configured to lower the temperature of the 3D part 124 (e.g., its most recently deposited upper layer). In yet another embodiment, the cooling device 520 may be positioned at least partially around or inside the build plate 140 and configured to lower the temperature of the build plate 140.

[0060] The printing material 120 can flow through a channel 510 within the 3D printer 500. For example, the printing material 120 will flow downstream through the channel 510 from the reservoir 512 to the feed channel 514, pressure chamber 516, and nozzle 114. The channel 510 may include a first (e.g., upstream) portion and a second (e.g., downstream) portion. The upstream portion may include the reservoir 512, feed channel 514, pressure chamber 516, or a combination thereof. The downstream portion may include the pressure chamber 516, nozzle 114, or both. The length and / or volume of the downstream portion of the channel 510 may be less than about 50%, less than about 40%, less than about 30%, less than about 20%, less than about 10%, less than about 5%, less than about 3%, or less than 1% compared to the length and / or volume of the upstream portion of the channel 510.

[0061] The 3D printer 500 (e.g., heating element 130) can maintain the build material 120 in the upstream portion of the flow channel 510 at a relatively low viscosity. The 3D printer 500 (e.g., cooling device 520) can make the build material 120 in the downstream portion of the flow channel 510 at a relatively high viscosity. In other words, the viscosity of the build material 120 in the upstream portion of the flow channel 510 may be below a predetermined viscosity threshold, while the viscosity of the build material 120 in the downstream portion of the flow channel 510 may be above a predetermined viscosity threshold. For example, in the case of an aluminum alloy, the viscosity is usually about 1 cps (mPa.s) in a low viscosity state. The predetermined viscosity threshold may be about 1.5 cps, about 2 cps, about 5 cps, about 10 cps, about 20 cps, about 50 cps, about 100 cps, or about 200 cps. In one example, the viscosity of the build material 120 in the downstream portion of the flow path 510 is initially about 0.5 cps to about 2 cps, or about 1 cps to about 1.4 cps, which may be increased by the cooling device 520 to about 5 cps to about 100 cps, or about 10 cps to about 50 cps. Since the high-viscosity build material 120 occupies only a small portion of the flow path 510, the excess resistance introduced by the high-viscosity build material 120 is proportionally small, and the ejection and / or discharge of the build material 120 and / or droplets 122 can be achieved with little excess force / pressure.

[0062] In one embodiment, the viscosity of the molding material 120 in the downstream portion of the flow channel 510 can be controlled (e.g., heated) by controlling (e.g., decreasing) the temperature of the molding material 120 in the downstream portion of the flow channel 510 using a cooling device 520. The temperature of the molding material 120 in the upstream portion of the flow channel 510 may be above a predetermined temperature threshold, and the temperature of the molding material 120 in the downstream portion of the flow channel 510 may be below a predetermined temperature threshold. The predetermined temperature threshold may be the melting point, liquidus temperature, and / or solidus temperature of the molding material 120. For example, aluminum alloy 6061 has a solidus temperature of 582°C and a liquidus temperature of 652°C, and the predetermined temperature may be approximately 630°C. In one example, the temperature of the material 120 in the downstream portion of the channel 510 is initially about 700°C to 900°C or about 800°C to 850°C, and may be cooled to about 500°C to 700°C or about 600°C to 630°C. The viscosity and / or temperature of the material 120 in the upstream portion of the channel 510 may be maintained by the cooling device 520 (for example, it may not be changed).

[0063] As described above, the molding material 120 may be a phase-change material (e.g., a metal and / or alloy) configured to change to different material states depending on the viscosity and / or temperature. More specifically, the phase-change material is capable of transitioning between a liquid state and a solid state within a narrow temperature range. For each simple (e.g., pure) metal, there is a single melting point, above which the metal is in a liquid state, and below which it is in a solid state. For alloys, there is a liquidus temperature, above which the alloy becomes a homogeneous liquid. There is also a solidus temperature (e.g., below the liquidus temperature), below which the alloy is 100% solid. At temperatures between the solidus and liquidus temperatures, the alloy is in a mixed state (e.g., sludge) where the solid and liquid fractions fluctuate. The viscosity of the molding material 120 will undergo a significant change in this transition region. For example, in the downstream portion of the flow path 510 (e.g., near or inside the nozzle 114), the temperature of the molding material 120 can be lowered by the cooling device 520 so that the molding material 120 transitions to a sludge state before being ejected from the nozzle 114.

[0064] The material undergoes a phase transition in response to thermal / temperature changes. As a result, the viscosity also undergoes a (e.g., rapid) change. The systems and methods described herein utilize the changes around this phase transition to enable the injection of the material into a higher viscosity state and / or a lower thermal energy state. For example, the viscosity in the downstream portion of the channel 510 may be 25% higher than the viscosity in the central or upstream portion of the channel 510. In other embodiments, this viscosity increase may be 50%, 2, 5, 10, 20, 50, or 100 times. In terms of phase transition, the solids content is approximately 0% in the upper portion of the channel 510, but higher than 1% in some portions of the lower channel 510. In some embodiments, this solids content may be higher than 2%, 5%, 10%, 20%, 30%, 40%, or 50%. In terms of temperature control, it may be above the liquidus temperature along the channel from the center to the upper portion. The temperature of the molding material 120 may be above the solidus temperature and below the liquidus temperature in the lower channel or at least along a portion of this lower channel. The solid content will increase as the temperature decreases toward the solidus temperature, reaching 100% when it falls below the solidus temperature. The exact rate of solidification in response to this temperature change is very specific to the actual composition of the molding material. Since the molding material 120 may still be in a transient state, the viscosity, solid content and / or temperature may not be uniform throughout the downstream portion of the channel 510. Therefore, the viscosity and / or solid content values ​​described above may indicate the maximum corresponding values ​​within the downstream portion of the channel 510, and the temperature values ​​may indicate the minimum temperature reached within the downstream portion of the channel 510.

[0065] The 3D printer 500 may also include a parameter detection device 530. The measurement parameters may be the viscosity of the build material 120 in the upstream portion of the flow path 510, the downstream portion of the flow path 510, the droplet 122, the 3D part 124, or a combination thereof. Alternatively, the measurement parameters may be the temperature of the build material 120 in the upstream portion of the flow path 510, the downstream portion of the flow path 510, the droplet 122, the 3D part 124, or a combination thereof. Alternatively, the measurement parameters may be the force and / or pressure required to eject the build material 120 through the 3D printer 500 and / or eject the droplet 122 from the nozzle 114. Alternatively, the measurement parameters may be the size, shape, and / or ejection frequency of the droplet 122. Alternatively, the measurement parameters may be the immersion and / or diffusion of the droplet 122 onto the 3D part 124 and / or the build plate 140.

[0066] Figure 6 shows a schematic cross-sectional side view of a part of another injection device 600 according to another embodiment. The injection device 600 is or may be an injection device for a 3D printer, a conventional inkjet printer, or various industrial applications. The injection device 600 may include a tank 612 configured to receive an injection material (modeling material) 120. In one example, the injection material 120 may be ink, and therefore the tank 612 may be called an ink tank. In another example, the injection material 120 may be the same as the modeling material (e.g., metal) described above. The injection device 600 may include one or more feed channels (three shown, 614A to 614C) flowing downstream from the tank 612. The injection device 600 may include one or more pressure chambers (three shown, 616A to 616C) flowing downstream from the channels 614A to 614C. The injection device 600 may include one or more piezoelectric elements (three are shown, 618A to 618C). In one example, the piezoelectric elements 618A to 618C are or may include piezoelectric devices. One piezoelectric element (e.g., 618A) may be connected to a corresponding pressure chamber (e.g., 616A) and configured to generate a pressure / injection pulse therein to inject the injection material 120. Each pressure chamber 616A to 616C may include nozzles 114A to 114C configured to discharge multiple droplets 122 of the injection material 120 in response to the pressure / injection pulse.

[0067] Figure 7 shows a flowchart of a method 700 for printing a 3D part 124 according to an embodiment. More specifically, the method 700 may be for controlling (e.g., increasing) the viscosity of the printing material 120 in the downstream portion of the flow path 510 in the 3D printer 500 (e.g., near the nozzle 114). An order for describing the method 700 is given below, but one or more steps of the method 700 may be performed in a different order, repeated, combined, or omitted.

[0068] Method 700 may include the step of introducing the build material 120 into the 3D printer 500 in 710. More specifically, this may include the step of introducing the build material 120 in a solid state into the ejector reservoir 112. A heating element 130 heats the build material 120 so that the build material 120 may transition to a liquid (e.g., molten) state in the ejector reservoir 112.

[0069] Method 700 may also include the step of generating multiple injection pulses in 720. This may include the step of the power supply 132 generating power pulses and transmitting them to the coil 134. The coil 134 may generate injection pulses (also called pressure pulses) in the ejector reservoir 112 that cause droplets 122 to be ejected from the nozzle 114 in response to the power pulses.

[0070] Method 700 may also include the step of measuring parameters in 730. The parameters may be measured using a parameter detection device 530. Alternatively, the parameters may be identified using a computing system 160 based on measurements made by the parameter detection device 530. As described above, the parameters may be the viscosity of the build material 120, the temperature of the build material 120, the force for ejecting the build material 120 through the 3D printer 500 or ejecting droplets 122 from the nozzle 114, the pressure for ejecting the build material 120 through the 3D printer 500 or ejecting droplets 122 from the nozzle 114, the size of the droplets 122, the shape of the droplets 122, the ejection frequency of the droplets 122, the immersion and / or diffusion of the droplets 122 onto the 3D part 124 or build plate 140, the diffusion of the droplets 122 onto the 3D part 124 or build plate 140, or a combination thereof. The parameters may be measured at one or more locations along the flow path 510 (for example, before the discharge of the droplet 122), within the droplet 122, on the 3D component 124, on the substrate 140, or a combination thereof.

[0071] Method 700 may also include a step in 740 of controlling the viscosity of the printing material 120. The viscosity may be controlled according to a measurement parameter. The 3D printer 500 (e.g., the computing system 160) may control (e.g., increase) the viscosity in the downstream portion of the channel 510. The 3D printer 500 (e.g., the computing system 160) may achieve this by varying (e.g., decreasing) the temperature of the printing material 120 in the downstream portion of the channel 510 through a cooling device 520. In one embodiment, the printing material 120 in the downstream portion of the channel 510 may be maintained in a liquid state in response to the decrease in temperature and / or the increase in viscosity. In another embodiment, the printing material 120 may transition from a liquid state to a sludge state in response to the decrease in temperature and / or the increase in viscosity. Method 700 may then loop back through steps 710, 720 and / or 730 and be repeated (i.e., Method 700 may be iterative).

[0072] In addition to viscosity changes associated with phase transitions, thermal / heat energy changes are also possible. During the phase transition between the liquid state and the sludge and / or solid state, there may be excess heat released, known as latent heat. The high viscosity state suggests that this latent heat has already been released. Therefore, little cooling is needed to solidify the extruded molding material 120 (i.e., the droplet 122 and / or 3D part 124) and enable rapid solidification of the droplet 122 and / or 3D part 124.

[0073] Increasing viscosity and / or decreasing thermal energy can be particularly beneficial in liquid metal jet 3D technology. For example, increasing viscosity and / or decreasing thermal energy can be beneficial when printing the leading edges of a 3D part 124. More specifically, at the extreme ends of the 3D part 124 (e.g., overhangs, sharp angles, thin walls), heat loss / dissipation due to conduction through the body of the 3D part 124 (usually the primary heat loss mechanism) is limited, making rapid cooling difficult. In another example, increasing viscosity and / or decreasing thermal energy can be beneficial during high-frequency jetting. As used here, high-frequency jetting refers to jetting droplets 122 at a jetting frequency higher than approximately 400 Hz for the example system. The rate of heat generation by the jetting mechanism of the 3D printer 500 may be proportional to the jetting frequency, droplet size / mass, heat capacity of the jetting material, etc. A high ejection frequency is defined as the rate at which the input thermal energy generated by the droplet 122 approaches or exceeds the cooling capacity of the system 160. As a result, it may be beneficial to remove excess heat during the ejection of the droplet 122. In yet another example, increasing viscosity and / or decreasing thermal energy may be beneficial when the 3D printer 500 includes multi-nozzle ejection and / or arrays, as shown in Figure 6. Multi-nozzle technology results in more heat being generated in a smaller area, increasing the need to extract heat during the ejection of the droplet 122.

[0074] The 3D printer 500 can utilize the ejection of a high-viscosity build material 120 and / or the ejection of the build material 120 in a high-viscosity state in at least two ways. Firstly, the high viscosity restricts the flow of droplets 122 in response to collisions with the 3D part 124 and / or build plate 140. This is directly related to the high viscosity. Secondly, rapid solidification is associated with the phase-change build material 120 in a high-viscosity state. This is particularly applicable to 3D printing related to liquid metal ejection.

[0075] Clause 1. A method for controlling the viscosity of an injectable material in an injection device, comprising the steps of: introducing the injectable material into the injection device, wherein the injectable material flows through a channel in the injection device, the channel comprising an upstream portion and a downstream portion; and increasing the maximum viscosity of the injectable material in the downstream portion of the channel to be at least 25% higher than the viscosity of the injectable material in the upstream portion of the channel.

[0076] 2. The method according to Clause 1, wherein the injection device comprises a 3D printer configured to print 3D parts.

[0077] 3. The method according to Clause 1, wherein the maximum viscosity of the injectable material in the downstream portion of the flow path is increased to be at least 50% higher than the viscosity of the injectable material in the upstream portion of the flow path.

[0078] 4. The method according to Clause 1, wherein the maximum viscosity of the injectable material in the downstream portion of the flow path is increased to be at least 200% higher than the viscosity of the injectable material in the upstream portion of the flow path.

[0079] 5. The method according to Clause 1, wherein the increase in the maximum viscosity of the propellant material in the downstream portion of the flow path causes the maximum solid content of the propellant material in the downstream portion of the flow path to be greater than about 1%.

[0080] 6. The method according to Clause 1, wherein the increase in the maximum viscosity of the injectable material in the downstream portion of the flow path results in the maximum solid content of the injectable material in the downstream portion of the flow path being greater than approximately 2%.

[0081] 7. The method according to Clause 1, wherein the increase in the maximum viscosity of the injectable material in the downstream portion of the flow path causes the maximum solid content of the injectable material in the downstream portion of the flow path to be greater than about 5%.

[0082] 8. The method according to Clause 1, wherein the maximum viscosity is increased by lowering the temperature of the injection material in the downstream portion of the flow path until the minimum temperature of the injection material in the downstream portion of the flow path is equal to or greater than the solidus temperature of the injection material and equal to or less than the liquidus temperature of the injection material.

[0083] 9. The method according to Clause 1, wherein the maximum viscosity is increased by lowering the temperature of the propellant in the downstream portion of the flow path until the minimum temperature of the propellant in the nozzle is equal to or greater than the solidus temperature of the propellant and equal to or less than the liquidus temperature of the propellant.

[0084] 10. The method according to Clause 1, wherein the maximum viscosity of the injection material in the downstream portion of the flow path is increased to about 2 cps to about 100 cps.

[0085] 11. The propellant material is the method according to Clause 1, wherein the propellant material includes a metal.

[0086] 12. The method according to Clause 1, wherein the upstream portion comprises an ejector reservoir of the injection device, and the downstream portion comprises a nozzle of the injection device.

[0087] 13. The method according to Clause 1, wherein the length, volume, or both of the downstream portion of the flow path is less than approximately 20% of the length, volume, or both of the upstream portion of the flow path.

[0088] 14. The method according to Clause 1, further comprising the step of measuring or identifying a parameter, wherein the maximum viscosity is increased according to the parameter.

[0089] 15. The method according to Clause 14, wherein the parameters include the maximum viscosity of the propellant, the temperature of the propellant, the force for propelling the propellant through the propellant device or for ejecting droplets of the propellant from the nozzle, the pressure for propelling the propellant through the propellant device or for ejecting droplets from the nozzle, the size of the droplets, the shape of the droplets, the frequency of droplet ejection, the immersion of the droplets into the 3D part or build plate, the diffusion of the droplets into the 3D part or build plate, or a combination thereof.

[0090] 16. The method according to Clause 14, wherein the parameter includes the maximum viscosity of the propellant material or the temperature of the propellant material, and the parameter is measured or specified in the downstream portion of the flow path or in droplets of the propellant material discharged from the nozzle of the propellant device.

[0091] 17. A method for controlling the viscosity of a molding material in a 3D printer, comprising the steps of: introducing the molding material into the 3D printer, wherein the molding material flows through a channel in the 3D printer, the channel comprising an upstream portion and a downstream portion; and increasing the viscosity of the molding material in the downstream portion of the channel to make the maximum solid content of the molding material in the downstream portion of the channel greater than about 1%.

[0092] 18. The method according to clause 17, wherein the viscosity is increased until the maximum solid content is greater than about 2%.

[0093] 19. The method according to clause 17, wherein the viscosity is increased until the maximum solid content is greater than about 5%.

[0094] 20. The method according to clause 17, wherein the viscosity is increased by lowering the temperature of the molding material in the downstream portion of the flow channel until the minimum temperature of the molding material in the downstream portion of the flow channel is equal to or greater than the solidus temperature of the molding material and equal to or less than the liquidus temperature of the molding material.

[0095] 21. The method according to clause 17, wherein the viscosity is increased by lowering the temperature of the molding material in the downstream portion of the flow path until the minimum temperature of the molding material in the nozzle is equal to or equal to the solidus temperature of the molding material and equal to or equal to the liquidus temperature of the molding material.

[0096] 22. The method according to clause 17, wherein the maximum viscosity of the molding material in the downstream portion of the flow path is increased to about 2 cps to about 100 cps.

[0097] 23. The method according to Clause 17, wherein the molding material includes metal.

[0098] 24. The method according to clause 17, wherein the upstream portion comprises the ejector reservoir of the 3D printer, and the downstream portion comprises the nozzle of the 3D printer.

[0099] 25. The method according to Clause 17, wherein the length, volume, or both of the downstream portion of the flow path is less than approximately 20% of the length, volume, or both of the upstream portion of the flow path.

[0100] 26. The method according to clause 17, further comprising the step of measuring or identifying a parameter, wherein the viscosity is increased in accordance with the parameter.

[0101] 27. The method according to Clause 26, wherein the parameters include the viscosity of the molding material, the temperature of the ejection material, the force for ejecting the ejection material through the 3D printer or ejecting droplets of the molding material from the nozzle, the pressure for ejecting the molding material through the 3D printer or ejecting droplets from the nozzle, the size of the droplets, the shape of the droplets, the frequency of droplet ejection, the immersion of the droplets into the 3D part or build plate, the diffusion of the droplets into the 3D part or build plate, or a combination thereof.

[0102] 28. The method according to Clause 26, wherein the parameter includes the viscosity of the molding material or the temperature of the molding material, and the parameter is measured or specified in the downstream portion of the flow path or in droplets of the ejected material ejected from the nozzle of the 3D printer.

[0103] 29. The method according to clause 17, wherein the viscosity is increased to above a predetermined viscosity threshold, and the viscosity of the molding material in the upstream portion of the flow path is maintained below the viscosity threshold.

[0104] 30. The method according to clause 29, wherein the predetermined viscosity threshold is approximately 10 cps.

[0105] 31. A method for controlling the temperature of a molding material in a 3D printer, comprising the steps of: introducing the molding material into the 3D printer, wherein the molding material flows through a channel in the 3D printer, the channel comprising an upstream portion and a downstream portion; and lowering the temperature of the molding material in the downstream portion of the channel until the minimum temperature in the downstream portion of the channel is equal to or greater than the solidus temperature of the molding material and equal to or less than the liquidus temperature of the molding material.

[0106] 32. The method according to clause 31, wherein the downstream portion of the flow path is equipped with the nozzle of the 3D printer.

[0107] 33. The method according to clause 31, wherein the step of lowering the temperature of the molding material in the downstream portion of the flow path is to increase the viscosity of the molding material in the downstream portion of the flow path.

[0108] 34. The method according to clause 31, wherein the temperature of the molding material in the upstream portion of the flow path is maintained above the liquidus temperature of the molding material.

[0109] 35. The method according to clause 31, wherein the temperature is reduced using a cooling device positioned at least partially around the nozzle of the 3D printer.

[0110] 36. The method according to clause 31, wherein the temperature is reduced until the viscosity of the molding material in the downstream portion of the flow path becomes approximately 2 cps to approximately 100 cps.

[0111] 37. The method according to clause 31, wherein the temperature is reduced until the viscosity of the molding material in the downstream portion of the flow path becomes approximately 5 cps to approximately 75 cps.

[0112] 38. The method according to Clause 31, wherein the molding material includes metal.

[0113] 39. The method according to clause 31, wherein the upstream portion comprises the ejector reservoir of the 3D printer, and the downstream portion comprises the nozzle of the 3D printer.

[0114] 40. The method according to Clause 31, wherein the length, volume, or both of the downstream portion of the flow path is less than approximately 20% of the length, volume, or both of the upstream portion of the flow path.

[0115] 41. The method according to clause 31, further comprising the step of measuring or identifying a parameter, wherein the temperature is reduced according to the parameter.

[0116] 42. The method according to Clause 41, wherein the parameters include the viscosity of the propellant, the temperature of the propellant, the force for propelling the propellant through the 3D printer or for ejecting droplets of the propellant from the nozzle, the pressure for propelling the propellant through the 3D printer or for ejecting droplets from the nozzle, the size of the droplets, the shape of the droplets, the frequency of droplet ejection, the immersion of the droplets into the 3D part or build plate, the diffusion of the droplets into the 3D part or build plate, or a combination thereof.

[0117] 43. The method according to Clause 41, wherein the parameter includes the viscosity of the molding material or the temperature of the molding material, and the parameter is measured or specified in the downstream portion of the flow path or in droplets of the ejected material ejected from the nozzle of the 3D printer.

[0118] 44. The method according to clause 31, wherein by lowering the temperature, the viscosity of the molding material in the downstream portion of the flow path increases to above a predetermined viscosity threshold, and the viscosity of the molding material in the upstream portion of the flow path is maintained below the predetermined viscosity threshold.

[0119] Although the numerical ranges and parameters defining the broad scope of these instructions are approximations, the numerical values ​​defined in the specific examples are reported as accurately as possible. However, each numerical value inherently contains a certain error that inevitably arises from the standard deviation observed in their respective test measurements. Furthermore, all ranges disclosed herein should be understood to encompass any and all subranges contained therein. For example, the range "less than 10" may include any and all subranges between (and including) the minimum value of zero and the maximum value of 10, i.e., any and all subranges having a minimum value greater than or equal to zero and a maximum value less than or equal to 10, e.g., 1 to 5.

[0120] While this instruction has been described with respect to one or more embodiments, substitutions and / or modifications may be made to the described examples without departing from the spirit and scope of the appended claims. For example, while a process is described as a series of actions or events, it should be understood that this instruction is not limited by the order of these actions or events. Some actions may be performed in a different order and / or simultaneously with other actions or events not described herein. Furthermore, not all processing steps are necessary to implement the methodology according to one or more aspects or embodiments of this instruction. Structural objects and / or processing steps may be added, or existing structural objects and / or processing steps may be excluded or modified. Also, one or more actions illustrated herein may be performed in one or more separate actions and / or steps. Furthermore, the terms “including,” “includes,” “having,” “has,” “with,” or their variations thereof, to the extent used in either the detailed description or the claims, are intended to be inclusive in a similar manner to the term “comprising.” The term “at least one of” is used to mean that one or more of the enumerated items may be selected. Also, in this description and the claims, the term “on” as used with respect to two materials one “on” the other means at least some contact between the materials, while “over” means that there is one or more additional intervening materials nearby, which may or may not be able to contact. Neither “on” nor “over” implies any directionality as used herein. The term “equal-angled” refers to a coating material preserved by a material whose angle is equal to that of the underlying material. The term "about" indicates that the listed values ​​may be modified to some extent, provided that the changes do not result in any discrepancies in processing or structure to the exemplary embodiments.The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” mean “being directly related” or “being related through one or more intermediate elements or components.” Finally, the terms “exemplary” or “illustrative” indicate that the description / statement is used as an example and not to suggest that it is ideal. Other embodiments of this teaching may become apparent to those skilled in the art from the examination of this specification and the practice of the disclosure herein. This specification and examples are for illustrative purposes only, and the true scope and spirit of this teaching are intended to be shown by the subsequent claims.

Claims

1. A method for printing 3D parts, A step of lowering the temperature of the material to be printed inside the nozzle of a 3D printer to below the melting point of the material, the step of transferring the material inside the nozzle from a liquid state to a solid state, A step of raising the temperature of the molding material inside the nozzle to above the melting point of the molding material, wherein the molding material inside the nozzle is transformed from a solid state to a sludge state, and the blockage and the molding material in the sludge state are discharged from the nozzle. A method for providing this.

2. The method according to claim 1, wherein the molding material includes a metal alloy.

3. The method according to claim 1, wherein the blockage comprises a substantially annular ring containing a metal oxide adhering to the inner surface of the nozzle, thereby reducing the effective diameter of the hole through the nozzle.

4. The method according to claim 1, further comprising the step of determining that the blockage is present inside the nozzle, wherein the temperature is reduced in accordance with the determination that the blockage is present.

5. A step of suspending the generation of injection pulses in response to the determination that the blockage is present, wherein droplets of the molding material are stopped from being ejected from the nozzle, The steps include restarting the generation of the injection pulse after the temperature has cooled down, The method according to claim 4, further comprising:

6. The steps include: after determining that the blockage is present, releasing the nozzle from the molding plate; The steps include: repositioning the nozzle relative to the molding plate after the temperature has risen; The method according to claim 4, further comprising:

7. The method according to claim 1, wherein the temperature rises by generating an injection pulse, causing heat to be generated within the nozzle.

8. The method according to claim 7, wherein, in addition to increasing the temperature, the injection pulse also causes both the blockage and the sludge-like molding material to be ejected from the nozzle, thereby increasing the effective diameter of the hole through the nozzle.

9. The method according to claim 1, wherein the temperature is raised by an external heater positioned at least partially around the nozzle.

10. The method according to claim 1, wherein the temperature is further increased by a heating element positioned upstream of the nozzle after the blockage and the molding material in a sludge state have been discharged from the nozzle.

11. The method according to claim 1, further comprising the step of printing a 3D part with the molding material after the blockage and the molding material in a sludge state have been discharged from the nozzle.

12. The method according to claim 1, wherein the temperature is cooled and then heated before or after the 3D part is printed.

13. The method according to claim 1, wherein the temperature is cooled down and then heated up after the first part of the 3D part has been printed and before the second part of the 3D part has been printed.

14. The method according to claim 1, wherein the temperature is lowered, and then raised after a predetermined amount of the molding material is extruded from the nozzle.

15. The method according to claim 1, wherein the temperature is lowered, and then raised after the molding material is extruded from the nozzle for a predetermined length of time.

16. A method for removing blockages from a 3D printer nozzle, A step of determining that the blockage is present inside the nozzle, wherein the blockage comprises a substantially annular ring containing a metal oxide adhering to the inner surface of the nozzle, and reduces the effective diameter of the hole through the nozzle; A step of pausing the generation of injection pulses, which involves stopping the ejection of droplets of the molding material containing metal from the nozzle, The steps include: releasing the nozzle from the build plate; A step of lowering the temperature of the molding material in the 3D printer, thereby causing a portion of the molding material in the nozzle to fall below its melting point, thereby transitioning from a liquid state to a solid state within the nozzle. A step of restarting the generation of the injection pulse, wherein heat is generated within the nozzle to at least partially melt the molding material within the nozzle so that the molding material transitions from a solid state to a sludge state within the nozzle, the injection pulse causes both the blockage and the molding material in the sludge state to be ejected from the nozzle, thereby increasing the effective diameter of the hole through the nozzle, A step of raising the temperature of the molding material in the 3D printer using a heating element to bring the molding material in the nozzle into a liquid state, wherein the temperature is raised after the blockage and the molding material in a sludge state have been ejected from the nozzle. The steps include: repositioning the nozzle and the molding plate after the temperature of the molding material has been raised; Once the nozzle and the build plate are realigned, the process involves printing a 3D part on the build plate using the build material. A method for providing this.

17. The step of determining the presence of the aforementioned blockage is: A step of taking in a feed using an obstruction detection device, wherein the obstruction detection device includes a camera, and the feed includes video or images of the inside of the nozzle, droplets discharged from the nozzle, or both; A step of determining the effective diameter of the hole based on the feed, A step of comparing the effective diameter with a predetermined nozzle diameter threshold, wherein it is determined that the blockage exists based on the comparison; The method according to claim 16, comprising:

18. The step of determining the presence of the aforementioned blockage is: A step of taking in a feed using an obstruction detection device, wherein the obstruction detection device includes a camera, and the feed includes video or images of the inside of the nozzle, droplets discharged from the nozzle, or both; A step of determining the size of the droplet based on the feed, A step of comparing the aforementioned size with a predetermined droplet size threshold, wherein it is determined that the blockage exists based on the comparison; The method according to claim 16, comprising:

19. The method according to claim 16, wherein, in response to the reduction in temperature, the other portion of the molding material upstream of the nozzle is maintained in the liquid state.

20. The method according to claim 16, wherein the injection pulse is restarted, but neither the blockage nor the molding material is ejected from the nozzle for a predetermined length of time, and the injection pulse causes the blockage and the molding material in a sludge state to be ejected from the nozzle after the predetermined length of time, the predetermined length of time being approximately 10 seconds to approximately 3 minutes.

21. A method for printing 3D parts, A step of using electromagnetic force to extrude a metal alloy from the nozzle of a 3D printer, wherein the metal alloy cools and solidifies after extrusion to form the 3D part, A step of determining that an obstruction is present inside the nozzle, A step of lowering the temperature of the metal alloy inside the nozzle to below the melting point of the metal alloy, the step of transitioning the metal alloy inside the nozzle from a liquid state to a solid state, A step of raising the temperature of the metal alloy inside the nozzle to above the melting point of the metal alloy, wherein the metal alloy inside the nozzle is transformed from a solid state to a sludge state, and the blockage and the metal alloy in the sludge state are discharged from the nozzle. A method for providing this.

22. The method according to claim 21, further comprising the step of transmitting a power pulse to one or more coils, wherein the one or more coils generate pulses of electromagnetic force in the nozzle in response to receiving the power pulses, and the temperature of the metal alloy in the nozzle rises in response to the pulses of electromagnetic force.

23. The method according to claim 22, wherein, in addition to the step of raising the temperature, the electromagnetic pulse also causes both the blockage and the sludge-like metal alloy to be discharged from the nozzle, thereby increasing the effective diameter of the hole through the nozzle.

24. The method according to claim 22, further comprising the step of using a heating element to raise the temperature of the metal alloy to transfer the metal alloy in the nozzle back to the liquid state, wherein the temperature is raised using the heating element after the blockage and the metal alloy in the sludge state have been discharged from the nozzle.

25. The step of determining whether the blockage is present inside the nozzle is: The steps include measuring the height of the 3D part, The steps include determining that the height is less than a predetermined height threshold, The method according to claim 21, comprising:

26. The method according to claim 21, wherein the step of determining that the blockage is present in the nozzle comprises comparing the amount or rate of the metal alloy introduced into the 3D printer with the amount or rate of the metal alloy extruded from the nozzle of the 3D printer.

27. The step of determining whether the blockage is present inside the nozzle is: The steps include: discharging a predetermined number of droplets of the metal alloy from the nozzle; A step of determining that the mass or volume of a predetermined number of droplets of the metal alloy is less than a predetermined threshold, The method according to claim 21, comprising:

28. The step of determining whether the blockage is present inside the nozzle is: A step of discharging a predetermined number of droplets of the metal alloy from the nozzle at a first time; A step of discharging a predetermined number of droplets of the metal alloy from the nozzle at a second time, wherein the first time and the second time are separated by one minute or more. The method according to claim 21, wherein the mass or volume of a predetermined number of droplets of the metal alloy discharged at the first time is greater than the mass or volume of a predetermined number of droplets of the metal alloy discharged at the second time by a predetermined threshold.

29. The method according to claim 21, wherein the step of determining that the blockage is present in the nozzle comprises measuring satellites of the metal alloy around the 3D part, wherein the mass of each satellite is less than 50% of the mass of the droplet of the metal alloy.

30. The step of determining whether the blockage is present inside the nozzle is: The steps include measuring the angle at which the metal alloy is discharged from the nozzle, A step of comparing the measured angle with a vertical line, wherein it is determined that the obstruction exists if the difference between the measured angle and the vertical line is greater than a predetermined angle threshold, The method according to claim 21, comprising:

31. The method according to claim 21, wherein the step of determining that the blockage is present in the nozzle comprises the step of determining that the speed at which droplets of the metal alloy are discharged from the nozzle is less than or equal to a predetermined speed threshold.

32. A nozzle configured to dispense multiple droplets of the molding material, A computing system configured to perform an operation, wherein the operation is The operation involves lowering the temperature of the molding material inside the nozzle to below the melting point of the molding material, thereby transitioning the molding material inside the nozzle from a liquid state to a solid state. The operation involves raising the temperature of the molding material inside the nozzle to above its melting point, causing the molding material inside the nozzle to transition from a solid state to a sludge state, and discharging the blockage and the molding material in the sludge state from the nozzle. A 3D printer equipped with [features / equipment].

33. The aforementioned operation is, An operation to determine that an obstruction is present inside the nozzle, The operation of pausing the generation of injection pulses and stopping the discharge of droplets from the nozzle in response to the determination that the aforementioned blockage is present, The operation of restarting the generation of the injection pulse after the temperature has cooled down, The 3D printer according to claim 32, further comprising the above.

34. A power supply configured to provide electricity, A metal coil configured to receive the aforementioned power and generate an injection pulse, wherein the injection pulse raises the temperature of the molding material in the nozzle above the melting point of the molding material, The 3D printer according to claim 32, further comprising:

35. In addition to increasing the temperature, the injection pulse also causes both the blockage and the sludge-like material to be ejected from the nozzle, thereby increasing the effective diameter of the hole through the nozzle, according to claim 34.

36. The 3D printer according to claim 32, further comprising a heating element positioned upstream of the nozzle, wherein the heating element begins to further increase the temperature after the blockage and the sludge-like material have been ejected from the nozzle.

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