Fluid system and method for supplying fluid to a print head in a 3D printer

Abstract

The fundamental problem of the present invention relating to a fluid system (12) and method for supplying fluid (7) to a print head (1) in a 3D printer is to provide a solution that ensures reliable supply of fluid to multiple metering units (2) within one or more print heads (1), reduces fluctuations in fluid pressure, and improves the printed image when fabricating layered 3D structures. This problem is solved with respect to the apparatus by having a distributor block (17) positioned between the storage tank (16) and the print head tank (14), the distributor block (17) having an inlet (18) connected to the storage tank (16) via a fluid supply line (19) and an outlet (20) connected to the storage tank (16) via a fluid return line (21), the distributor block (17) having at least two other connection parts (22), each of which is connected to a print head tank (14) via a fluid line (15), a pump (23) positioned in the fluid supply line (19), and a control valve (34) positioned in the fluid return line (21).

Description

Technical Field

[0001] The present invention relates to a fluid system for supplying fluid to a print head in a 3D printer, wherein the print head has a plurality of metering units and is connected to a print head tank, and the print head tank is at least indirectly connected via a fluid line to a storage tank for storing the fluid.

Background Art

[0002] The present invention also relates to a method for supplying fluid to a print head in a 3D printer, in which method the fluid is pumped at least indirectly from a storage tank into the print head tank of the print head, and the print head tank is provided connected to the print head for supplying fluid to the print head.

[0003] In particular, the present invention relates to a fluid system and method for supplying fluid to a print head in a 3D printer, in which a fluid such as a binder is applied by means of nozzles of metering units arranged in the print head onto a layer of particulate shaping material formed on the build field of the 3D printer, thereby achieving selective curing during the production of a 3D structure in the 3D printer.

[0004] It is known to use so-called 3D printing or so-called 3D printing methods for manufacturing individual or mass-produced components, workpieces or molds. In such printing methods, three-dimensional components or workpieces are manufactured by stacking them in layers.

[0005] This stacking is carried out in a computer-controlled manner from one or more liquid or solid materials according to pre-defined dimensions and shapes. The settings for the component or workpiece to be printed can be provided, for example, by a computer-aided design system (CAD).

[0006] During the printing of 3D structures or components, a physical or chemical curing or melting process is carried out in the particulate shaping material, also known as the molding material. Materials used for such 3D printing methods include shaping materials or molding materials, such as plastics, synthetic resins, ceramics, minerals, or non-curing deposits like sand, as well as metals.

[0007] When implementing 3D printing, various manufacturing processes are known.

[0008] However, several of these manufacturing processes are described in the following exemplary method steps, namely, - A step of partially or entirely stacking particulate material, also called particulate material or powdered laminate material, on a so-called build field, thereby forming a layer consisting of uncured particulate material, wherein the partial or entire stacking of particulate material includes stacking and smoothing of the particulate material; - A step of selectively curing an adhered layer consisting of uncured particulate material in a predetermined subregion, for example by selective compression, by printing or adhesion of a processing agent such as a fluid or binder using a print head, or by using a laser or electron beam. - A step of repeating a preceding method step at a different layer level in order to stack components or workpieces in layers, wherein for this purpose the components or workpieces to be stacked or printed in layers on a build field are lowered together with the build field by one layer level or layer thickness, or the 3D printing apparatus is raised relative to the build field by one layer level or layer thickness, and then the new layer is stacked partially or entirely. - The step of subsequently removing loose, uncured particulate molding material surrounding the manufactured component or workpiece. It includes.

[0009] Particulate shaping materials are generally understood to be a collection of individual particles of a substance or mixture of substances, each particle having a three-dimensional extended length. These particles can be considered primarily circular, elliptical, or elongated, and it is possible to provide an average diameter for such particles, usually in the range of 0.01 mm to 0.4 mm. Such particulate shaping materials may possess fluid properties.

[0010] Based on prior art, various methods are known for fabricating 3D structures, or for extruding and accumulating particulate material onto a build field to fabricate 3D structures. Similarly, various fluid systems and methods for supplying fluid to the print head in a 3D printer are known.

[0011] For example, it is known that a print head can be used to print or deposit a processing agent, such as a fluid or binder, and the print head contains multiple so-called metering units, each equipped with a corresponding nozzle. In one example, the nozzles of the metering units are arranged in the print head in a matrix with multiple columns and multiple rows. Each metering unit in the print head can be driven and controlled independently, and the metering unit releases a predetermined amount (droplet) of fluid or binder through its nozzle onto particulate material piled up on the build field of the layer to be manufactured.

[0012] Based on Patent Document 1, print heads, the use of print heads, and 3D printing methods are known. The problem to be solved is to provide a print head that avoids the reported drawbacks of the prior art.

[0013] To address the challenges, a print head is provided, particularly suitable for selectively applying a printing fluid onto a particulate material during the manufacturing of three-dimensional models using additive manufacturing technology. A print head tank containing the printing fluid is connected to a print head module, which guides the printing fluid into a pump chamber and to the nozzles of the print head. To fill the print head tank, it is connected to an intermediate tank via a tube. The intermediate tank can be connected via a valve block to one of several storage containers for the printing fluid.

[0014] Furthermore, a metallic support is provided to which the print head module is mounted. Additionally, a plastic fluid guide is provided to allow the printing fluid to pass through the metallic support, and this plastic fluid guide is positioned by the metallic support. Therefore, the metallic portion is cut out to allow the plastic portion, which does not directly affect the positioning of the print head, to be used for the fluid guide.

[0015] Based on Patent Document 2, a method for manufacturing three-dimensional objects by additive manufacturing from mixed resins is known. The problem to be solved is to provide a method for additive manufacturing that enables the production of objects having diverse or finely tuned mechanical properties.

[0016] To solve this problem, a method is provided for manufacturing a three-dimensional object from a mixed resin by additive manufacturing, wherein the mixed resin comprises at least one photopolymerizable first component and optionally, preferably, at least one or more curable second components different from the first component.

[0017] In this method, after providing a first resin and a second resin, the first resin and the second resin are mixed to produce a mixed resin, from which a three-dimensional object having mechanical properties can be manufactured.

[0018] In an additive manufacturing apparatus, a three-dimensional object is produced from a mixed resin after the mixed resin is selectively discharged into the build area of ​​the additive manufacturing apparatus. Various resins are stored in separate tanks and supplied to the mixing apparatus via valves and pumps, and metered through corresponding nozzles.

[0019] A common problem with known prior art is that the fluid system supplying fluid to the printhead and its nozzles has areas, such as a pipeline, where the fluid to be pumped to the printhead either has no flow velocity, at least temporarily, or remains stationary within the tank or pipeline. This situation occurs, for example, when the printhead or an intervening tank does not need to pump or refill fluid. If a tank or intermediate tank in the fluid supply system has a correspondingly high fill level, it is likely that it will no longer be necessary to continue filling or refilling this tank or intermediate tank for a certain period of time. Only when a corresponding sensor in this tank or intermediate tank detects a decrease in the fill level is fluid refilled.

[0020] Fluids in tanks, intermediate tanks, and especially in pipelines can form so-called aggregates or lumps. This can occur with organic fluids, inorganic fluids, or binders that bind particulate materials. The formation of such aggregates or lumps can lead to clogging and / or pressure fluctuations in the fluid system, and / or an increase in the viscosity of the binder. Furthermore, clogging of pipelines, valves, or nozzles can lead to inaccuracies or errors in the fabrication of 3D structures in a 3D printer, for example, because too little fluid is being pumped to the print head. Fluctuations or drops in fluid pressure can lead to degradation of the print image from one or more print heads, and consequently, inaccuracies or errors in the fabrication of 3D structures.

[0021] Furthermore, in known fluid systems, varying fluid pressures can occur within the printhead conduits and metering units, depending on the complexity and number of printheads or metering units to which the fluid should be supplied. These pressure losses within the conduits are particularly caused by varying conduit lengths, bends with varying radii of curvature, or conduit materials with varying surface properties or roughness. These varying fluid pressures lead to varying volumes of fluid droplets discharged from the metering unit nozzles, and consequently, inaccuracies or errors in the fabrication of 3D structures.

[0022] In a system where fluid is supplied from a single tank to multiple print heads, a temporary high demand for fluid within a print head can cause a pressure drop in the inflow pipeline. Furthermore, this can lead to a relatively rapid decrease in the fill level of the corresponding tank. In this case as well, pressure fluctuations or pressure losses can result in degradation of the printed image, which has corresponding consequences for the quality of the 3D structure to be produced.

[0023] Patent Document 3 discloses a liquid discharge device that includes a circulation passage through which liquid circulates, a liquid discharge head disposed in the circulation passage for discharging liquid, a bypass passage connecting an upstream section and a downstream section of the liquid discharge head, a switch for switching between a first path in which the bypass passage is part of the circulation passage and a second path in which the bypass passage is not part of the circulation passage, a pressure generator for generating pressure to circulate liquid in the circulation passage, a degassing device for degassing the liquid in the circulation passage, and a control circuit for performing a degassing process in which the liquid is degassed by circulating the liquid in the circulation passage.

[0024] From Patent Document 4, a metering unit in a print head of a 3D printer and a method for metering a fluid in a 3D printer are known. The problem to be solved is to improve the metering unit in the print head of the 3D printer and the method for metering the fluid in the 3D printer to achieve improved quality and reliability during metering of the fluid by the metering unit.

[0025] To solve the problem, a metering unit having a supply pipe passage and a discharge pipe passage is provided. Thereby, the fluid is kept in a state of moving within the metering unit and can flow through the metering unit. This flow-through also includes the fluid outlet region formed at the nozzle. Therefore, the fluid is kept in a flowing and moving state even in the fluid outlet region within the metering unit, and changes in the properties of the fluid known from the prior art, such as moisture loss, density change, viscosity change, change in the surface tension of the fluid, oxidation phenomenon, etc. are avoided. Because the fluid is always renewed or replaced.

[0026] Therefore, partial solutions for preventing aggregation, agglomeration or clogging are known, at least in the region of the metering unit and thus in the region of the print head. Solutions for the fluid in the tank, intermediate tank and especially in the pipeline are not provided.

[0027] Therefore, there is a need for an improved fluid system and an improved method for supplying fluid to a print head in a 3D printer that prevents the aggregation or agglomeration of the fluid within the fluid system.

Prior Art Documents

Patent Documents

[0028]

Patent Document 1

Patent Document 2

Patent Document 3

[0029] The object of the present invention is to improve the fluid system and method for supplying fluid to a print head in a 3D printer, ensuring reliable fluid supply to multiple metering units within one or more print heads, reducing fluid pressure fluctuations, and improving the printed image when fabricating layered 3D structures. [Means for solving the problem]

[0030] The problem of the present invention is solved by a fluid system having the features described in claim 1, which is an independent claim. An improved version is described in a dependent claim.

[0031] According to prior art, a fluid system that supplies fluid to a print head has at least one print head having multiple metering units. This print head is connected to a print head tank via a corresponding supply line, and this print head tank is connected to a storage tank via a fluid line. The fluid for the 3D printer is stored in this storage tank.

[0032] Such storage tanks may be located inside or outside the 3D printer. If the storage tanks are located outside the 3D printer, they may be positioned, for example, next to or on top of the 3D printer.

[0033] According to the present invention, each print head is positioned within the print head unit and connected to a corresponding print head tank via a supply conduit, or alternatively, via a supply conduit passage and an outlet conduit passage.

[0034] In the so-called print head unit of the fluid system of the 3D printer according to the present invention, a print head tank and at least one print head having a plurality of metering units are arranged. The print head is connected to the print head tank via a supply conduit that supplies a binder-like fluid from the print head tank to the metering units of the print head. Alternatively, the print head is connected to the print head tank via a supply conduit that supplies a binder-like fluid from the print head tank to the metering units of the print head, and an outlet conduit that leads the fluid back from the metering units of the print head into the print head tank. In both variations, the fluid is moved from the print head tank to the print head by corresponding means, such as a pump.

[0035] When multiple print heads are arranged within a print head unit, fluid is supplied in parallel from a single print head tank to the connected print heads, each equipped with a metering unit. The fluid moves through all the print heads, each in a separate circuit via supply and outlet passages. Such a print head unit may contain, for example, six print heads, each connected to a corresponding print head tank via supply and outlet passages.

[0036] In the fluid system, a distributor block is positioned between the storage tank and the print head tank, the distributor block having an inlet connected to the storage tank via a fluid supply line and an outlet connected to the storage tank via a fluid return line, the distributor block having at least two other connection points, each of which is connected via a single fluid line to a single print head tank located within the print head unit, a pump is positioned in the fluid supply line and a control valve is positioned in the fluid return line.

[0037] The distributor block according to the present invention is connected to the storage tank via a fluid supply pipeline to supply fluid from the storage tank. To prevent aggregation or condensation, the distributor block is also specified to be connected to the storage tank via a fluid return pipeline. The fluid is pumped from the storage tank into the distributor block via the inlet by means of pumping the fluid, such as a pump located in the fluid supply pipeline. Furthermore, the fluid is pumped back into the storage tank from the distributor block via the outlet, i.e., it moves in a circular or fluid-circulating manner. Such continuous circulation of the fluid in a fluid-circulating manner prevents the formation of aggregates or condensation, or only minor aggregates or condensation. Such continuous motion of the fluid causes any aggregates or condensation that may have formed to break down again.

[0038] The distributor block is specified to have an inlet or inlet for introducing fluid supplied from a storage tank via a fluid supply pipeline into the hollow chamber of the distributor block. Furthermore, the distributor block has a first outlet or outlet for leading fluid from the hollow chamber of the distributor block to the storage tank via a fluid return pipeline. In addition, the distributor block has a number of other outlets from the hollow chamber, each of which is connected to one fluid pipeline for supplying to the corresponding printhead tank. The number of additional outlets provided corresponds to the number of printhead tanks to which fluid is connected or to which fluid should be supplied. In one example, there may be 2 to 6 additional outlets.

[0039] Furthermore, it is specified that the fluid supply and return pipelines have appropriate means to enable control of fluid circulation between the storage tank and the distributor block without fluid flowing out of the system or pipeline. This allows fluid circulation between the storage tank and the distributor block to be initiated, its mass flow rate to be controlled, or interrupted.

[0040] This allows for a continuous supply of fluid from the storage tank to the distributor block in the first variation, provided that fluid circulation is activated or continuously initiated by appropriate means. This also allows for a second variation, where fluid is supplied to the distributor block from the storage tank only for a specified period. Such appropriate means affecting fluid circulation include, for example, pumps and / or control valves.

[0041] The specified period is, for example, the time between two printing processes or print jobs in a 3D printer. During these times, the distributor block is filled with fluid by fluid circulation activated so that there is enough fluid in the distributor block to allow the subsequent printing process to run completely.

[0042] It is also specified that a distributor block and at least one print head unit, which includes a print head tank and at least one print head connected to the print head tank, are located within a print unit that can move on the build field of the 3D printer.

[0043] Similarly, the distributor block is specified to have a substantially rectangular hollow chamber, the cross-section of which is at least partially V-shaped, and the distributor block is specified to have an outlet that is spaced apart from the inlet by a difference in height and is positioned higher than the inlet.

[0044] The distributor block according to the present invention is configured such that the outlet, which returns the fluid in the hollow chamber of the distributor block to a storage tank via a fluid return pipeline, is located in the distributor block above the inlet, which supplies fluid from the storage tank to the hollow chamber of the distributor block. Therefore, the level of the fluid in the hollow chamber of the distributor block must reach a height or elevation difference that exceeds the inlet before the fluid is discharged from the distributor block through the outlet. This elevation difference between the outlet and the inlet is, for example, 10 mm to 80 mm.

[0045] It is also specified that positive pressure be generated in the fluid-filled hollow chamber of the distributor block by adjusting the pressure in the fluid supply pipeline to be higher than the pressure in the fluid return pipeline. To this end, corresponding sensors and pressure forming means are provided so that these pressure conditions in the pipeline can be monitored and adjusted. This positive pressure ensures, on the one hand, that fluid circulation occurs from the lower inlet to the higher outlet, and on the other hand, that the same pressure is maintained at another connection point in the lower region, i.e., the deepest region of the hollow chamber, despite the circulation between the inlet and outlet.

[0046] According to the present invention, as a means of pressure formation, a pump is provided in the fluid supply pipeline and a control valve is provided in the fluid return pipeline. For example, an appropriate control signal starts the operation of the pump and opens the control valve at least partially. This pressurizes the fluid from the storage tank through the fluid supply pipeline to the distributor block. When the fluid filling level in the distributor block reaches the outlet located higher up in the distributor block, the fluid flows from the distributor block through the fluid return pipeline and the control valve back to the storage tank in the fluid circulation. Now, if a constant mass flow of fluid is induced in the fluid supply pipeline by the pump, and the cross-sectional area of ​​the control valve in the fluid return pipeline is reduced, the pressure acting on the fluid in the region between the pump and the control valve increases, and in this case, according to the present invention, positive pressure is also generated in the hollow chamber of the distributor block.

[0047] Furthermore, the distributor block is specified to have a hollow chamber, which, in addition to its substantially rectangular parallelepiped shape, has at least a partially V-shaped cross-section, and this V-shaped cross-section tapers downwards. Thus, the hollow chamber, for example, is substantially rectangular in its first part, while in its second part, which together with the first part forms the entire hollow chamber, it has at least a partially V-shaped cross-section.

[0048] It is also specified that another connection point is located in the deepest part of the hollow chamber, on the distributor block, at least in the narrowest part of its partially V-shaped cross-section.

[0049] The inlet and outlet are located in the upper region of the distributor block with a difference in elevation. Multiple other outlets are located in the distributor block in the deepest region within the hollow chamber of the distributor block. In this region, the V-shaped cross-section has the smallest width. In the longitudinal direction of the hollow chamber of the distributor block, in the extended portion of this deepest region, two or more other connections are located along a virtual horizontal line.

[0050] The configuration of the hollow chamber in the distributor block, such that the hollow chamber is approximately 2 to 5 times taller than its width, and the V-shape of the hollow chamber tapering downwards, ensures a uniform pressure condition at all points in the deepest region for the other outlets connected to the distributor block. As a result, fluid is supplied uniformly at the same pressure to all printhead tanks connected to the other outlets, thereby improving the print image quality of the printheads.

[0051] Exemplary dimensions for the hollow chamber of the distributor block are 20 mm to, for example, 220 mm in length, and this length depends on the number of other connections in the distributor block. The width of the hollow chamber at its widest point is, for example, in the range of 40 mm to 100 mm, while the width of the hollow chamber at its narrowest point may be in the range of approximately 10 mm to 20 mm. The height of the hollow chamber is, for example, in the range of 60 mm to 200 mm. The width of the vertical passage located in the deepest part of the hollow chamber and the diameter of the hole for another connection in the deepest part of the hollow chamber are in the range of approximately 4 mm to 10 mm.

[0052] Furthermore, the distributor block is specified to be positioned at a small distance from the print head tank of the print head unit within the print unit moving on the build field. In addition, the fluid lines from the other outlet of the distributor block to the individual print head tanks are as equal in length as possible. This configuration results in equivalent fluid pressure in all connected print head tanks and print heads of all print head units, and therefore results in high-quality printed images.

[0053] The storage tank is also specified to have means for controlled motion of the fluid contained within it, such as a rotor. This controlled motion of the fluid within the storage tank prevents the formation of collations or aggregates. Such a storage tank may have a capacity of 10 to 100 liters.

[0054] In such a fluid system described herein for supplying fluid to a print head, multiple valves, throttles, sensors, filters, and pumps are required to move the fluid in a corresponding manner and supply it to individual groups of structures, but it will be apparent to those skilled in the art that such elements are not fully described herein.

[0055] The problem of the present invention can also be solved by a method having the features described in the independent claim 6. Another improved version is described in the dependent claim.

[0056] In the first step, fluid is pumped from the storage tank into the distributor block, and the distributor block is provided connected to the storage tank via fluid supply and fluid return lines to generate continuous fluid circulation between the storage tank and the distributor block. In the second step, fluid is pumped from the distributor block to multiple printhead tanks via a plurality of other connections provided to the distributor block, and a pump is provided in the fluid supply line to generate a mass flow of fluid for fluid circulation, and a control valve is provided in the fluid return line to throttle the circulating mass flow of fluid generated by the pump, thereby generating positive pressure in the region between the pump and the control valve, and simultaneously generating positive pressure in the hollow chamber of the distributor block.

[0057] Unlike conventional technology in which fluid is pumped from a storage tank to a printhead tank of a printhead, and the printhead tank is connected via a single pipeline to supply fluid to the printhead, the present invention, in the first step, pumps the fluid from the storage tank to a distributor block. Since this distributor block is connected to the storage tank either via a fluid supply pipeline or a fluid return pipeline, the fluid is moved or circulated in a fluid circulation, starting from the storage tank, passing through the distributor block, and returning to the storage tank. This circulation prevents aggregation or condensation in the distributor block of the fluid system, as well as in the fluid supply and return pipelines.

[0058] In the second step, the fluid is to be pumped from the distributor block to multiple printhead tanks via multiple other connections provided within the distributor block. This supplies fluid from the distributor block to the multiple printhead tanks, each of which supplies fluid to at least one printhead equipped with a metering unit. Such printhead tanks may be connected, for example, to the corresponding printheads via supply lines to supply fluid to those printheads. Alternatively, such printhead tanks may be connected to 2 to 6 printheads to supply fluid to each printhead.

[0059] In particular, according to the present invention, a pump is provided in the fluid supply pipeline to generate a mass flow of fluid for fluid circulation, and a control valve is provided in the fluid return pipeline to restrict the mass flow of the fluid circulating from the pump. By adjusting the restriction of the mass flow of fluid, positive pressure is generated and regulated in the region between the pump and the control valve, and at the same time, positive pressure is also generated in the hollow chamber of the distributor block.

[0060] Similarly, a distributor block is provided having a hollow chamber having at least a partially V-shaped cross-section, with another connection provided located in the deepest region of the hollow chamber, thereby generating the same fluid pressure for the fluid supplied to all printhead tanks from which the distributor block is supplied.

[0061] The distributor block according to the present invention has a substantially rectangular hollow chamber, the hollow chamber having at least a partially V-shaped cross-section. Preferably, the distributor block has a V-shaped cross-section in its lower region. In the deepest region of the distributor block, where the V-shaped cross-section has the smallest width, a vertical passage and another connection are arranged in the longitudinal extension of the deepest region. Through these other connections, the printhead tank supplies fluid to a plurality of printhead units via their respective fluid lines. Due to the configuration of the distributor block having a V-shaped cross-section in at least the lower region, and the arrangement of the horizontal connection in the deepest region of the hollow chamber, all the other connections provide the same fluid pressure for supplying to the connected printhead tanks. A vertical passage is provided in the other connection located in the deepest region of the hollow chamber of the distributor block to ensure that a sufficient amount of fluid is supplied in the narrowest region of the V-shaped cross-section of the hollow chamber. One vertical passage is provided for each of the other connections.

[0062] Furthermore, within the print head unit, fluid is supplied from the print head tank to each of the multiple metering units of each print head via a single fluid supply line, and the circulating fluid is returned from each of the multiple metering units of each print head to the print head tank via a single fluid return line.

[0063] The print head tank and the print heads connected to the print head tank are provided within a so-called print head unit. Such a print head unit may have a print head tank and a plurality of print heads connected to this print head tank.

[0064] In such a printhead unit, the printhead tank is connected via a fluid supply line to one or more printheads to supply fluid from the printhead tank to the metering unit of one or more printheads. Furthermore, the printhead tank is connected via a fluid return line to one or more printheads to return fluid from the metering unit of one or more printheads back into the printhead tank. This creates a circulation that starts from the printhead tank, passes through the metering unit of one or more printheads, and returns to the printhead tank. This circulation prevents aggregation or condensation within the printhead unit, or allows for the decomposition of aggregation or condensation after it has formed.

[0065] The present invention provides the same fluid pressure for supplying connected print head tanks and circulates it to supply all print heads within the 3D printer's printing unit similarly, thereby achieving uniform, high-quality printed images when fabricating 3D structures in a 3D printer.

[0066] Furthermore, it is specified that the print head unit and distributor block be provided within a print unit that can move on the build field of the 3D printer.

[0067] A distributor block and multiple print head units are arranged within a print unit that can move on the build field of a 3D printer, with each print head unit having one print head tank and one or more print heads supplied in circulation from this print head tank.

[0068] In this printing unit, the distributor block is positioned such that the fluid conduits leading from the distributor block to the printhead tank are of as equal a length as possible, thereby ensuring consistent pressure conditions from the distributor block through the printhead tank to the printhead, in order to achieve accurate print images without errors from the printhead of the printing unit.

[0069] Furthermore, the distributor block is positioned such that the fluid conduits leading from the distributor block to the print head tank can be laid with the smallest possible radius of curvature, or a constant radius of curvature. This is done in such a way that equal pressure conditions are maintained within the group of structures.

[0070] Fluid is supplied from a storage tank to a distributor block within the printing unit, either continuously or simply for a specified period, in which case the specified period is also specified as a time when the printing process by the 3D printer's print head is not taking place.

[0071] This allows, through defined drive control of the pump and control valve, that in the first variation, fluid can be supplied to the distributor block from the storage tank for a specified period of time. For example, during the period between two printing processes or print jobs in a 3D printer, the distributor block is filled with fluid from the storage tank, ensuring that there is enough fluid in the distributor block to allow the subsequent printing process or print job to run completely.

[0072] This allows for the deliberate adjustment of pressure in the region between the pump and the control valve, and even within the distributor block, through defined drive control of the pump and control valve in the second variation.

[0073] The above-mentioned features and advantages of the present invention will be better understood and recognized by carefully examining the subsequent detailed description of preferred but non-limiting exemplary configurations of the present invention together with the accompanying drawings. [Brief explanation of the drawing]

[0074] [Figure 1] This diagram shows a print head equipped with multiple metering units, based on conventional technology. [Figure 2] This figure shows a conventional fluid system. [Figure 3] This diagram shows the arrangement of multiple print heads within a print head unit using conventional technology. [Figure 4] This is a diagram showing the fluid system according to the present invention. [Figure 5a] This figure shows a distributor block according to the present invention. [Figure 5b] This diagram shows the distributor block according to the present invention from a different perspective. [Figure 5c] This figure shows the distributor block according to the present invention from yet another perspective. [Modes for carrying out the invention]

[0075] Figure 1 shows a cross-sectional view of a print head 1 equipped with multiple metering units 2 in a conventional 3D printer, as well as an example where three metering units 2 are installed within a single print head 1. Such an arrangement of metering units 2 can be carried out in the print head 2, for example, in the form of a matrix with multiple rows and multiple columns.

[0076] Each metering unit 2 of the print head 1 has a nozzle 3 directed toward the build field 4. The metering units 2 are at least partially separated from each other, for example by corresponding chamber walls, without impairing the supply of fluid 7. On this build field 4, particulate material (not shown in Figure 1) is piled up, smoothed, and cured for the layered lamination of a 3D structure. For this purpose, methods known in the prior art for piling up, smoothing, and curing particulate material are used.

[0077] The illustrated print head 1 has a supply pipe passage 5 and an outlet pipe passage 6. A fluid 7, such as a binder, is supplied to the print head 1 through the supply pipe passage 5 and discharged back from the print head 1 through the outlet pipe passage 6. Thus, the print head 1 and its metering unit 2 are also circulated by the fluid 7. This circulation 8 of the fluid 7 through the print head 1 is illustrated by several small arrows. Although a print head 1 with circulation 8 is illustrated exemplary in Figure 1, the present invention also allows for the use of a print head without circulation 8, i.e., one with only a supply pipe for supplying the fluid 7, which is not shown in Figure 1.

[0078] The two large arrows on the supply pipe passage 5 and outlet pipe passage 6 shown in Figure 1 indicate the flow direction of the circulating fluid 7. The fluid 7 inside the metering unit 2 of the print head 1 is prevented from flowing out through the nozzle 3 by negative pressure.

[0079] Each metering unit 2 is provided with a means 9 for generating a mechanical force to meter a fluid 7 onto particulate material on the build field 4 via the nozzle 3 of the metering unit 2. This means 9 generates a mechanical force such as a pressure wave. This pressure wave, starting from the means 9 itself, propagates in the direction of the corresponding nozzle 3 by the fluid 7 in the corresponding metering unit 2, thereby working to meter droplets 10 through the corresponding nozzle 3. Such means 9 may be, for example, a piezoelectric element that operates according to the piezoelectric effect.

[0080] The droplet 10 reaches the surface of the particulate material on the build field 4, causing selective hardening of the material at the point of impact, thereby creating a sub-region of the 3D structure to be fabricated.

[0081] The illustrated print head 1, equipped with a metering unit 2 divided into multiple chambers, moves over the build field 4 as usual. This allows for precise metering of the fluid where necessary for forming the 3D structure or 3D components.

[0082] In the example shown in Figure 1, filter elements 11 are further provided in the supply pipe passage 5 and the outlet pipe passage 6. Alternatively, only the filter elements 11 in the supply pipe passage 5 or the filter elements 11 in the outlet pipe passage 6 may be provided. These filter elements 11 help prevent clogging or contamination. This can prevent clogging of, for example, the nozzle 3.

[0083] This print head 1, known from prior art, keeps the fluid 7 in motion within the metering unit 2 of the print head 1, allowing it to circulate 8 through the print head 1. This prevents moisture loss, changes in the viscosity of the fluid 7, oxidation, and narrowing of the nozzle 3 due to drying, and consequently, errors during metering and errors in the printed image.

[0084] Figure 2 shows a conventional fluid system 12'. This fluid system 12' works to supply a fluid 7, such as a binder, to a print head 1 of a 3D printer (not shown in Figure 2). Inside the print head unit 13 are a print head tank 14 and at least one print head 1 having a plurality of metering units 2. The print head 1 is connected to the print head tank 14 via a supply pipe passage 5 that supplies a fluid 7, such as a binder, from the print head tank 14 to the metering units 2 of the print head 1, and an outlet pipe passage 6 that leads the fluid 7 from the metering units 2 of the print head 1 back into the print head tank 14. The fluid 7 is moved from the print head tank 14 to the print head 1 and circulated 8 back again by corresponding means, such as a pump (not shown).

[0085] The print head tank 14 is connected via a fluid conduit 15 to a storage tank 16 that stores fluid 7. Thus, the fluid 7 can be guided from the storage tank 16 through the fluid conduit 15 to the print head tank 14 of the print head unit 13 shown in Figure 2. Typically, such a storage unit 16 is connected to another print head tank 14 of another print head unit 13 via another fluid conduit 15. This is illustrated in Figure 2 by three additional fluid conduits 15.

[0086] Figure 3 shows the arrangement of multiple print heads 1 within a print head unit 13 according to the prior art. When multiple print heads 1, each equipped with multiple metering units 2, are arranged in this manner within a single print head unit 13, a single print head tank 14 supplies fluid to all connected print heads 1, each equipped with a metering unit 2, in parallel. In this case, the fluid 7 is circulated through all print heads 1 via a supply pipe passage 5 and an outlet pipe passage 6 in a single circulation path 8. In the print head unit 13 illustrated in Figure 3 as an example, three print heads 3 are arranged and connected to the corresponding print head tank 14. The fluid pipeline 15 that supplies the fluid 7, located in the print head tank 14, is not shown in Figure 3.

[0087] Figure 4 shows a fluid system 12 according to the present invention. Within the print head unit 13 of the fluid system 12 according to the present invention are a print head tank 14 and at least one print head 1 having a plurality of metering units 2. The print head 1 is connected to the print head tank 14 via a supply pipe passage 5 that supplies a fluid 7, such as a binder, from the print head tank 14 to the metering units 2 of the print head 1, and an outlet pipe passage 6 that leads the fluid 7 from the metering units 2 of the print head 1 back into the print head tank 14. The fluid is moved from the print head tank 14 to the print head 1 and back again in a circulation path 8 by a corresponding means (not shown), such as a pump. It is also possible to arrange a plurality of print heads 2 within the print head unit 13, although this is not shown in Figure 4.

[0088] According to the present invention, a distributor block 17 is positioned between a storage tank 16 and a print head tank 14. The distributor block 17 has an inlet 18 connected to the storage tank 16 via a fluid supply line 19 and an outlet 20 connected to the storage tank 16 via a fluid return line 21. The distributor block 17 has at least two other connection points 22. Each of these other connection points 22 is connected to each of the print head tanks 14 in the corresponding print head unit 13 via a fluid line 15. In the example shown in Figure 4, the distributor block 17 has four other connection points 22. The connection between one other connection point 22 and the corresponding print head tank 14 via the corresponding fluid line 15 is illustrated in Figure 4. Another connection is indicated by a plurality of fluid lines 15, only partially shown, illustrated in another connection point 22.

[0089] The distributor block 17 is connected to the storage tank 16 via a fluid supply pipeline 19 to supply fluid 7 from the storage tank 16. To prevent aggregation and condensation, the distributor block 17 is also specified to be connected to the storage tank 16 via a fluid return pipeline 21. The fluid 7 is pumped from the storage tank 16 into the distributor block 17 via the inlet 18 by means of pumping the fluid 7, such as a pump 23 located in the fluid supply pipeline 19. The fluid 7 is then pumped back from the distributor block 17 to the storage tank 16 via the outlet 20, i.e., circulated within the fluid circuit, by another pump, for example (not shown). This continuous circulation of the fluid prevents the formation of aggregates or condensation, or causes any aggregates or condensation that may have formed to break down again.

[0090] According to the present invention, a pump 23 is located in the fluid supply pipeline 19 to generate a mass flow of fluid 7 for fluid circulation, and a control valve 34 is located in the fluid return pipeline 21 to restrict the mass flow of fluid 7 generated by the pump 23. By adjusting the restriction of the mass flow of fluid 7, pressure or positive pressure is generated in the region between the pump 23 and the control valve 34 according to the present invention, and at the same time, positive pressure is also generated in the hollow chamber 26 of the distributor block 17.

[0091] The distributor block 17 and at least one print head unit 13, which comprises a print head tank 14 and at least one print head 1 connected to the print head tank 14, are located within a print unit 24 of the 3D printer, which is mobile on a build field (not shown). In Figure 4, three print head units 13 are arranged within the print unit 24, as an example.

[0092] It is also specified that the storage tank 16 has means 25 for the controlled motion of the fluid 7 contained within the storage tank 16, such as a rotor. This controlled motion of the fluid 7 within the storage tank 16 prevents the formation of assemblies or aggregates.

[0093] Figures 5a, 5b, and 5c show the distributor block 17 according to the present invention from three different perspectives. Figure 5a shows the distributor block 17 according to the present invention in a perspective view. Figure 5b shows the interior of the distributor block 17 in a longitudinal section. Figure 5c shows the distribution block 17 in a cross-sectional view.

[0094] In Figure 5a, the distributor block 17 is illustrated with six additional connections as an example. Fluid lines 15 leading to their respective printhead tanks 14 are connected to these additional connections 22. The number of additional connections 22 provided corresponds to the number of printhead tanks 14 (not shown) to which the fluid 7 is connected or supplied from the distributor block 17. The inlet 18 and outlet 20 are located on the opposite side of the distributor block 17 in Figure 5a and are therefore not visible.

[0095] In the vertical cross-sectional view shown in Figure 5b, a substantially rectangular hollow chamber 26 of the distributor block 17 can be seen. An inlet 18 can be seen in the upper right region of the hollow chamber 26, and through this inlet 18, the fluid 7 reaches the hollow chamber 26 of the distributor block 17 from the storage tank 16 and via the fluid supply pipeline 19. The storage tank 16 and the fluid supply pipeline 19 are not shown in Figure 5b.

[0096] An outlet 20 can be seen in the upper left region of the hollow chamber 26, and through this outlet 20, the fluid 7 reaches the storage tank 16 from the hollow chamber 26 of the distributor block 17 via the fluid return pipeline 21. The storage tank 16 and the fluid return pipeline 21 are not shown in Figure 5b.

[0097] The distributor block 17 according to the present invention is configured such that the outlet 20 is located above the inlet 18 within the hollow chamber 26. Therefore, the level of the fluid 7 in the hollow chamber 26 of the distributor block 17 must reach a height or elevation difference 28 that exceeds the inlet 18 before the fluid 7 is discharged from the hollow chamber 26 of the distributor block 17 via the outlet 20. This elevation difference 28 between the outlet 20 and the inlet 18 is, for example, 10 mm to 80 mm.

[0098] Furthermore, it is specified that the distributor block 17 has a hollow chamber 26 having a cross-section 29 that tapers downwards and is at least partially V-shaped. In this example, the hollow chamber 26 is substantially rectangular in shape in the upper part and has a cross-section 29 that is at least partially V-shaped in the lower part.

[0099] In the lower region of the hollow chamber 26 of the distributor block 17, there is at least one region 27 located at the deepest point. In this region 27, the V-shaped cross-section 29 has the smallest width.

[0100] Two or more additional connection points 22 are arranged along a virtual horizontal line in the extended portion of the deepest region 27 in the longitudinal direction of the distributor block 17 or the hollow chamber 26. The example shown in Figure 5b shows six additional connection points 22 arranged horizontally in this manner.

[0101] The configuration of the hollow chamber 26 of the distributor block 17, such that the hollow chamber 26 has a height 30 that is approximately 2 to 5 times the width 31 of the hollow chamber 26, and the configuration of the hollow chamber 26, which tapers downwards in a V-shape 29, ensures that a uniform pressure condition in the form of uniform positive pressure is achieved at all points in the deepest region 26 for another outlet 22 connected to the distributor block 17. Thus, fluid 7 with the same pressure is uniformly supplied to all print head tanks 14 connected to the other outlets 22, which are not shown in Figures 5a, 5b, and 5c, thereby improving the print image quality of the print head 1, which is also not shown. The hollow chamber 26 of the distributor block 17 has a length 32 as shown in Figure 5b. In the hollow chamber configuration shown in Figure 5b, a short vertical passage 33 is provided in the lowest region, where the width of the V-shaped cross section 29 is smallest, thereby ensuring that a sufficient amount of fluid 7 is supplied to the other connection.

[0102] Regarding the method, in the first step, fluid 7 is pumped from the storage tank 16 into the distributor block 17, and the distributor block 17 is provided connected to the storage tank 16 via a fluid supply line 19 and a fluid return line 21 in order to generate continuous fluid circulation between the storage tank 16 and the distributor block 17. In the second step, the pressurized fluid 7 in the distributor block 17 is pumped from the distributor block 17 to a plurality of print head tanks 14 via a plurality of other connections 22 provided in the deepest region 27 of the distributor block 17, through their respective fluid lines 15.

[0103] The distributor block 17 is connected to the storage tank 16 via both the fluid supply pipeline 19 and the fluid return pipeline 21. Through these fluid supply pipelines 19 and 21, the fluid 7 is moved or circulated so that it originates in the storage tank 16, passes through the distributor block 17, and returns to the storage tank 16 in the fluid circulation. As a result, aggregation or condensation is prevented both within the distributor block and within the pipelines 19 and 21 of the fluid system 12.

[0104] It is stipulated that a positive pressure is generated in the hollow chamber 26 of the distributor block 17, which is filled with fluid 7, by adjusting the pressure in the fluid supply pipeline 19 to be higher than the pressure in the fluid return pipeline 21. To achieve this, corresponding sensors and means for forming the pressure are provided so that this pressure condition of the fluid 7 in the pipeline can be monitored and adjusted.

[0105] In the second step, the fluid 7 from the distributor block 17 to the multiple print head tanks 14 is supplied to the print head tanks 14 under the same fluid pressure within all connected fluid lines 15.

[0106] The fluid supply pipeline 19 and the fluid return pipeline 21 between the storage tank 16 and the distributor block 17 have an interface 23, which allows for the temporary interruption of fluid circulation between the storage tank 16 and the distributor block 17 without the fluid 7 flowing out of the system or pipelines 19 and 21.

[0107] Therefore, the distributor block 17 can be permanently supplied with fluid 7 from the storage tank 16 only when the interface 23 is engaged or during a specified period when the interface 23 is not open.

[0108] The specified period is, for example, the time between two printing processes or print jobs in a 3D printer. During this time, fluid from the storage tank 16 is filled into the distributor block 17 via the connected interface 23, so that a sufficient amount of fluid 7 is contained within the distributor block 17, thereby allowing the subsequent printing process to be fully carried out with the interface 23 open. [Explanation of symbols]

[0109] 1. Print head 2 Measuring Units 3 nozzles 4 Build Field 5 Supply pipe passage 6 Outlet pipe passage 7 fluid 8 circulation 9. Means of forming a force 10 droplets 11 filter elements 12,12' Fluid System 13. Printhead Unit 14 Printhead Tank 15 Fluid line 16 storage tanks 17. Distributor Block 18 Inlet 19 Fluid supply pipeline 20 Outlet 21 Fluid return pipeline 22 Another connection point 23 pumps 24 Printing Units 25 Means for controlled movement 26 Hollow chamber 27 The deepest region 28 Altitude difference 29 V-shaped cross-section 30 Height 31 width 32 Length 33 aisles 34. Adjustment valve

Claims

1. A fluid system (12) for supplying fluid (7) to a print head (1) in a 3D printer, wherein the print head (1) has a plurality of metering units (2) and is connected to a print head tank (14), the print head tank (14) is at least indirectly connected to a storage tank (16) for storing fluid (7) via a fluid pipeline (15), a distributor block (17) is positioned between the storage tank (16) and the print head tank (14), and the distributor block (17) is connected via a fluid supply pipeline (19) A fluid system (12) having an inlet (18) connected to a storage tank (16) and an outlet (20) connected to the storage tank (16) via a fluid return line (21), wherein the distributor block (17) has at least two other connection parts (22), each of which is connected to a print head tank (14) via a fluid line (15), a pump (23) located in the fluid supply line (19), and a control valve (34) located in the fluid return line (21).

2. The fluid system (12) according to claim 1, characterized in that the distributor block (17) and at least one print head unit (13) including a print head tank (14) and at least one print head (1) connected to the print head tank (14) are arranged in a print unit (24) that can move on the build field of the 3D printer.

3. The fluid system (12) according to claim 1 or 2, characterized in that the distributor block (17) has a hollow chamber (26), the hollow chamber (26) is configured to have at least a partially V-shaped cross section (29), and within the distributor block (17), the outflow section (20) is spaced apart from the inflow section (18) by a height difference (28) and is positioned higher than the inflow section (18).

4. The fluid system (12) according to any one of claims 1 to 3, characterized in that the other connection portion (22) is located in the region (27) at the deepest position of the hollow chamber (26) on the distributor block (17) in the narrowest region of the at least partially V-shaped cross section (29).

5. A fluid system (12) according to any one of claims 1 to 4, characterized in that each print head (1) is arranged within a print head unit (13) and connected to a corresponding print head tank (14) via a supply pipe passage (5) and an outlet pipe passage (6).

6. A method for supplying fluid (7) to a print head (1) in a 3D printer, wherein the fluid (7) is pumped from a storage tank (16) at least indirectly into at least one print head tank (14) of the print head (1), and the print head tank (14) is connected to the print head (1) to supply the fluid (7) to the print head (1), In the first step, the fluid (7) is pumped from the storage tank (16) into the distributor block (17), and the distributor block (17) is connected to the storage tank (16) via a fluid supply line (19) and a fluid return line (21) to generate continuous fluid circulation between the storage tank (16) and the distributor block (17), and in the second step, the fluid (7) is pumped from the distributor block (17) to a plurality of print head tanks (14) via a plurality of other connections (22) provided within the distributor block (17). A method characterized by pumping fluid (7) into the fluid supply pipeline (19) and providing a pump (23) that causes a mass flow of fluid (7) for fluid circulation into the fluid supply pipeline (19), providing a control valve (34) in the fluid return pipeline (21) that restricts the mass flow of fluid (7) that is circulating due to the pump (23), and by adjusting the mass flow of fluid (7) with the control valve (34), generating positive pressure in the region between the pump (23) and the control valve (34), and simultaneously generating positive pressure in the hollow chamber (26) of the distributor block (17).

7. The method according to claim 6, characterized in that the distributor block (17) is provided having a hollow chamber (26) having at least a partially V-shaped cross-section, and the other connection portion (22) is provided located in the deepest region (27) of the hollow chamber (26), thereby generating the same fluid pressure of the fluid (7) supplied to all print head tanks (14) supplied from the distributor block (17) via the corresponding fluid conduit (15).

8. The method according to claim 6 or 7, characterized in that, within the print head unit (13), fluid (7) is supplied from the print head tank (14) to the metering unit (2) of each print head (1) via a single supply pipe passage (5), and the circulating fluid (7) is returned from the metering unit (2) of each print head (1) to the print head tank (14) via a single outlet pipe passage (6).

9. The method according to any one of claims 6 to 8, characterized in that the print head unit (13) and the distributor block (17) are provided within a print unit (24) that can move on the build field of a 3D printer.

10. The method according to any one of claims 6 to 9, characterized in that continuous fluid circulation between the storage tank (16) and the distributor block (17) is generated using a pump (23) provided in the fluid supply pipeline (19) or the fluid return pipeline (21).

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