Three-dimensional modeling device

Abstract

To provide a three-dimensional shaping device excellent in ejection stability of a binder.SOLUTION: A three-dimensional shaping device comprises: an ejection head including a nozzle configured to eject a binder containing water, a water-soluble resin and a wetting agent, an individual liquid chamber communicating with the nozzle, an inflow path configured to make the binder flow into the individual liquid chamber, and an outflow path configured to make the binder flow out of the individual liquid chamber; and a circulation flow path configured to circulate the binder flowing out of the outflow path to the inflow path.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a three-dimensional modeling apparatus. [Background technology]

[0002] For example, a three-dimensional modeling apparatus is known that manufactures a three-dimensional object by a binder method in which a binder is discharged onto a powder bed, as shown in Patent Document 1. In the three-dimensional modeling apparatus described in Patent Document 1, the polyvinyl alcohol contained in the binder is set to 3% by mass to 7% by mass with respect to the binder, so that a model with a reduced carbon content can be obtained while maintaining the binding properties of the modeling material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US 2020 / 0017699 Specification Summary of the Invention [Problem to be solved by the invention]

[0004] However, the binder used in the three-dimensional modeling apparatus described in Patent Document 1 contains glycol ether, a wetting agent, in an amount of 3% by mass to 7% by mass relative to the binder. Therefore, the carbon content of the model cannot be sufficiently reduced by simply reducing the ratio of the binder. On the other hand, reducing the content of the wetting agent in the binder may result in a decrease in the binder and ejection stability. [Means for solving the problem]

[0005] The three-dimensional modeling apparatus of the present invention includes a discharge head having a nozzle that discharges a binder containing water, a water-soluble resin, and a wetting agent, an individual liquid chamber that communicates with the nozzle, an inflow flow path that causes the binder to flow into the individual liquid chamber, and an outflow flow path that causes the binder to flow out of the individual liquid chamber; and a circulation flow path that circulates the binder that has flowed out from the outlet flow path to the inlet flow path. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic diagram of a three-dimensional modeling apparatus according to the present invention. [Diagram 2] FIG. 2 is a plan view of the ejection head shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view of the ejection head shown in FIG. [Figure 4] FIG. 4 is a schematic diagram of a carriage that supports the ejection head shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] <Embodiment> Fig. 1 is a schematic diagram of a three-dimensional modeling apparatus of the present invention. Fig. 2 is a plan view of the discharge head shown in Fig. 1. Fig. 3 is a cross-sectional view of the discharge head shown in Fig. 1. Fig. 4 is a schematic diagram of a carriage supporting the discharge head shown in Fig. 1.

[0008] The three-dimensional modeling apparatus will be described in detail below based on preferred embodiments shown in the accompanying drawings. In addition, in Fig. 2 and Fig. 3, mutually orthogonal X-axis, Y-axis, and Z-axis are illustrated, and the tip side of the arrow of each axis is the "+" side, and the base end side of the arrow of each axis is the "-" side.

[0009] The three-dimensional modeling apparatus 1 includes a plurality of ejection heads 100 that eject binder onto a powder bed (not shown), a main tank 201 that stores the binder ejected from the ejection heads 100, a reduced pressure sub-tank 210, a pressurized sub-tank 220, a first liquid delivery pump 202, a second liquid delivery pump 203, a first manifold 230 and a second manifold 240, a head tank 251, a head tank 252, and a degassing device 260.

[0010] The first liquid supply pump 202 supplies the binder from the decompression sub-tank 210 to the pressurization sub-tank 220 via the binder path 284. A degassing device 260 and a filter 261 are arranged in the binder path 284. The degassing device 260 is for removing dissolved gas in the binder. The filter 261 is for capturing and removing foreign matter in the binder.

[0011] Further, the second liquid feed pump 203 feeds the binder from the main tank 201 to the reduced pressure sub-tank 210 via a binder path 289. A filter is disposed in the binder path 289 to capture and remove foreign matter in the binder.

[0012] The decompression sub-tank 210 has a gas chamber 210a in which the binder and gas coexist. The decompression sub-tank 210 is provided with a liquid level detection means 211 for detecting the liquid level, and an electromagnetic valve 212 for opening the gas chamber 210a to the atmosphere.

[0013] A second adjustment device 207 that reduces the pressure inside the decompression sub-tank 210 is connected to the decompression sub-tank 210. The second adjustment device 207 has a regulator 213, a decompression buffer tank 214, and a vacuum pump 215 that is a gas pump. An electromagnetic valve 216 is provided between the regulator 213 and the decompression buffer tank 214. An electromagnetic valve 217 is provided in the decompression buffer tank 214.

[0014] The pressurizing sub-tank 220 has a gas chamber 220a in which the binder and gas coexist. The pressurizing sub-tank 220 is provided with a liquid level detection means 221 for detecting the liquid level, and an electromagnetic valve 222 serving as an atmosphere opening mechanism for opening the inside of the tank to the atmosphere.

[0015] A first adjustment device 206 that pressurizes the inside of the pressurization sub-tank 220 is connected to the pressurization sub-tank 220. The first adjustment device 206 has a regulator 223, a pressurization buffer tank 224, and a compressor 225. In addition, a solenoid valve 226 is provided between the regulator 223 and the pressurization buffer tank 224. In addition, a solenoid valve 227 is provided in the pressurization buffer tank 224.

[0016] The pressurized sub-tank 220 is connected to the first manifold 230 via a binder path 281 .

[0017] The first manifold 230 is connected to the supply port side of the ejection head 100 via a supply flow path 231. The supply flow path 231 is connected to the supply port of the ejection head 100 via a head tank 251. A solenoid valve 232 that opens and closes the path is provided in the supply flow path 231 upstream of the head tank 251. In addition, the first manifold 230 is provided with a pressure sensor 233.

[0018] The reduced pressure sub-tank 210 is connected to the second manifold 240 via a binder path 282 .

[0019] The second manifold 240 is connected to a discharge port of the discharge head 100 via a discharge flow path 241. The discharge flow path 241 is connected to a discharge port of the discharge head 100 via a head tank 252. A solenoid valve 242 that opens and closes the path is provided in the discharge flow path 241 downstream of the head tank 252. In addition, the second manifold 240 is provided with a pressure sensor 243.

[0020] Here, the path that passes through the reduced pressure sub-tank 210, the binder path 284, the degassing device 260, the pressurized sub-tank 220, the binder path 281, the first manifold 230, the ejection head 100, the second manifold 240, the reduced pressure sub-tank 210, and returns to the pressurized sub-tank 220 constitutes a circulation path 301. When the amount of circulating liquid in the circulation path 301 falls below a predetermined amount, the binder is replenished from the main tank 201 to the reduced pressure sub-tank 210.

[0021] In this embodiment, the first manifold 230 is disposed at a higher position than the second manifold 240.

[0022] In addition, the pressurized sub-tank 220 is disposed at a position higher than the position at which the supply port, which is the supply opening of the ejection head 100, is disposed. Specifically, the pressurized sub-tank 220 is disposed so that its inner bottom surface is disposed at a position higher than the supply port of the ejection head 100.

[0023] On the other hand, the reduced pressure sub-tank 210 is disposed at a position lower than the position of the discharge port, which is the discharge outlet of the discharge head 100. Specifically, the reduced pressure sub-tank 210 is disposed so that the liquid level of the binder contained in the reduced pressure sub-tank 210 is lower than the discharge port of the discharge head 100.

[0024] Next, a method for circulating the binder in the three-dimensional modeling apparatus 1 will be described.

[0025] (1) Binder flow from the main tank 201 to the decompression sub-tank 210 When the liquid level detection means 211 detects a shortage of binder in the reduced pressure sub-tank 210, the second liquid supply pump 203 is driven to supply binder from the main tank 201 to the reduced pressure sub-tank 210 via the binder path 289 until the liquid level is detected as full by the liquid level detection means 211.

[0026] (2) Binder flow from the decompression subtank 210 to the pressurization subtank 220 By driving the first liquid supply pump 202 , the binder can be supplied from the reduced pressure sub-tank 210 to the pressurized sub-tank 220 via the binder path 284 .

[0027] (3) Binder flow from the pressurized sub-tank 220 to the ejection head 100 to the decompressed sub-tank 210 The first regulator 206 adjusts the pressure in the pressurized sub-tank 220 to a target pressure (for example, a pressure that results in pressurization), while the second regulator 207 adjusts the pressure in the depressurized sub-tank 210 to a target pressure (for example, a pressure that results in negative pressure).

[0028] This generates a pressure difference between the pressurized sub-tank 220 and the reduced pressure sub-tank 210. In response to this pressure difference, the binder can be circulated from the pressurized sub-tank 220 through the binder path 281, the first manifold 230, the plurality of supply flow paths 231, the plurality of head tanks 251, the plurality of ejection heads 100, the plurality of head tanks 252, the plurality of discharge flow paths 241, the second manifold 240, and the binder path 282 to the reduced pressure sub-tank 210.

[0029] The liquid level detection means 211, 221 can use a float type binder detection method, a method that detects the presence or absence of a binder based on the voltage output detected using at least two or more electrode pins, or other liquid level detection methods using a laser.

[0030] Moreover, by driving the solenoid valves 222 and 212, the insides of the pressurized sub-tank 220 and the depressurized sub-tank 210 can be made to communicate with the atmosphere.

[0031] Next, a detailed description will be given of the configuration of the ejection head 100. Note that since the ejection heads 100 have the same configuration, one ejection head 100 will be representatively described.

[0032] As shown in FIG. 3, the ejection head 100 includes a plurality of members, such as a flow path forming substrate 10 as a flow path substrate, a communication plate 15, a nozzle plate 20, a protective substrate 30, a case member 40, and a compliance substrate 49.

[0033] The flow passage forming substrate 10 is made of a silicon single crystal substrate, and a vibration plate is formed on one surface of the substrate 10. The vibration plate is made of a single layer or a multilayer selected from a silicon dioxide layer and a zirconium oxide layer.

[0034] The flow path forming substrate 10 is provided with a plurality of pressure chambers 12, which are individual liquid chambers, partitioned by a plurality of partition walls. The pressure chambers 12 are arranged at a predetermined pitch along the X-axis direction in which a plurality of nozzles 21 for ejecting a binder are arranged. In the present embodiment, one row of pressure chambers 12 arranged in the X-axis direction is provided. The flow path forming substrate 10 is arranged such that the in-plane direction includes the X-axis direction and the Y-axis direction. In the present embodiment, the portion between the pressure chambers 12 arranged in the X-axis direction of the flow path forming substrate 10 is called a partition wall. This partition wall is formed along the Y-axis direction. In other words, the partition wall refers to the portion of the flow path forming substrate 10 that overlaps with the pressure chambers 12 in the Y-axis direction.

[0035] In this embodiment, only the pressure chamber 12 is provided on the flow path forming substrate 10, but a flow path resistance imparting section having a narrower cross-sectional area across the flow path than the pressure chamber 12 may be provided so as to impart flow path resistance to the binder supplied to the pressure chamber 12.

[0036] A vibration plate is formed on one surface side in the -Z-axis direction of such a flow path forming substrate 10, and a first electrode 60, a piezoelectric layer 70, and a second electrode 80 are laminated on the vibration plate by film formation and lithography to form a piezoelectric actuator 300. In this embodiment, the piezoelectric actuator 300 is an energy generating element that generates a pressure change in the binder in the pressure chamber 12. Here, the piezoelectric actuator 300 is also called a piezoelectric element, and refers to a portion including the first electrode 60, the piezoelectric layer 70, and the second electrode 80. In general, one of the electrodes of the piezoelectric actuator 300 is a common electrode, and the other electrode and the piezoelectric layer 70 are patterned for each pressure chamber 12. In this embodiment, the first electrode 60 is a common electrode of the piezoelectric actuator 300, and the second electrode 80 is an individual electrode of the piezoelectric actuator 300, but there is no problem even if this is reversed due to convenience of the drive circuit and wiring. In the above example, the diaphragm and the first electrode 60 act as a diaphragm, but of course the present invention is not limited to this, and for example, the diaphragm may not be provided and only the first electrode 60 may act as a diaphragm. Also, the piezoelectric actuator 300 itself may essentially function as a diaphragm.

[0037] Moreover, a lead electrode 90 is connected to the second electrode 80 of each of the piezoelectric actuators 300, and a voltage is selectively applied to each of the piezoelectric actuators 300 via the lead electrode 90. Moreover, a protection substrate 30 is bonded to the surface of the flow path forming substrate 10 in the -Z axis direction.

[0038] A piezoelectric actuator holding section 31 having a space that does not hinder the movement of the piezoelectric actuator 300 is provided in a region of the protective substrate 30 facing the piezoelectric actuator 300. The piezoelectric actuator holding section 31 only needs to have a space that does not hinder the movement of the piezoelectric actuator 300, and the space may be sealed or not. The piezoelectric actuator holding section 31 is formed to a size that covers the row of the piezoelectric actuators 300 arranged side by side in the X-axis direction as a whole. Of course, the piezoelectric actuator holding section 31 is not particularly limited to this, and may cover the piezoelectric actuators 300 individually, or may cover each group consisting of two or more piezoelectric actuators 300 arranged side by side in the X-axis direction.

[0039] It is preferable to use a material having a thermal expansion coefficient substantially the same as that of the flow path forming substrate 10, such as glass or a ceramic material, for such a protective substrate 30. In this embodiment, the protective substrate 30 is formed using a silicon single crystal substrate made of the same material as the flow path forming substrate 10.

[0040] The protective substrate 30 is provided with a through hole 32 penetrating the protective substrate 30 in the Z-axis direction. The vicinity of the end of the lead electrode 90 drawn out from each piezoelectric actuator 300 is extended so as to be exposed in the through hole 32, and is electrically connected to the flexible cable 120 in the through hole 32. The flexible cable 120 is a flexible wiring board, and in this embodiment, a driving circuit 121, which is a semiconductor element, is mounted on it. Note that the lead electrode 90 and the driving circuit 121 may be electrically connected without the flexible cable 120. A flow path may be provided in the protective substrate 30.

[0041] In addition, a case member 40 is fixed onto the protective substrate 30. The case member 40 defines, together with the protective substrate 30, supply flow paths communicating with the multiple pressure chambers 12. The case member 40 is joined to the surface of the protective substrate 30 opposite to the flow path forming substrate 10, and is also joined to a communication plate 15, which will be described later.

[0042] The case member 40 is provided with a first liquid chamber portion 41 that constitutes a part of the first common liquid chamber 101, and a second liquid chamber portion 42 that constitutes a part of the second common liquid chamber 102. The first liquid chamber portion 41 and the second liquid chamber portion 42 are located on both sides of a row of pressure chambers 12 in the Y-axis direction, respectively. It has been established.

[0043] Each of the first liquid chamber 41 and the second liquid chamber 42 has a concave shape that opens to the -Z side surface of the case member 40, and is provided continuously across the multiple pressure chambers 12 arranged side by side in the X-axis direction.

[0044] In addition, the case member 40 is provided with a supply port 43 that communicates with the first liquid chamber portion 41 and supplies binder to the first liquid chamber portion 41, and a discharge port 44 that communicates with the second liquid chamber portion 42 and discharges the binder from the second liquid chamber portion 42.

[0045] Furthermore, the case member 40 is provided with a connection port 45 that communicates with the through hole 32 of the protection board 30 and through which the flexible cable 120 is inserted.

[0046] On the other hand, on the +Z side of the flow path forming substrate 10 opposite the protective substrate 30, a communication plate 15, a nozzle plate 20, and a compliance substrate 49 are provided.

[0047] A plurality of nozzles 21 that eject binder in the +Z-axis direction are formed in the nozzle plate 20. In this embodiment, as shown in Fig. 2, the plurality of nozzles 21 are arranged on a straight line along the X-axis direction to form a single nozzle row 22.

[0048] The nozzle 21 has a first nozzle 21a and a second nozzle 21b with different inner diameters arranged side by side in the Z-axis direction, which is the plate thickness direction of the nozzle plate 20. The first nozzle 21a has a smaller inner diameter than the second nozzle 21b. The first nozzle 21a is arranged on the outer side of the nozzle plate 20, i.e., on the +Z side, and the binder is ejected from the first nozzle 21a in the +Z-axis direction to the outside as binder droplets. That is, the second axis direction in which the binder is ejected in this embodiment is the Z-axis direction in this embodiment.

[0049] The second nozzle 21b is disposed on the -Z side of the nozzle plate 20 and communicates with the first flow path 201A extending in the Y-axis direction. That is, the first axis direction, which is the extension direction of the first flow path 201A, is the Y-axis direction in this embodiment. The Y-axis direction, which is the first axis direction, and the Z-axis direction, which is the second axis direction, are perpendicular to each other.

[0050] In this way, by providing the nozzle 21 with the first nozzle 21a having a relatively small inner diameter, the flow rate of the binder can be improved, and the flying speed of the binder droplets ejected from the nozzle 21 can be improved. Also, by providing the nozzle 21 with the second nozzle 21b having a relatively large inner diameter, when the binder in the individual flow passage 200A is circulated from the first common liquid chamber 101 to the second common liquid chamber 102, which will be described in detail later, the portion of the nozzle 21 that is not affected by the circulating flow can be reduced. That is, a flow of the binder can be generated in the second nozzle 21b during circulation, and the velocity gradient in the nozzle 21 can be increased, so that the binder in the nozzle 21 can be replaced with new binder supplied from upstream. However, if the inner diameter of the second nozzle 21b is made too large compared to the first nozzle 21a, the ratio of the inertance between the second nozzle 21b and the first nozzle 21a becomes large, and the position of the meniscus of the binder in the nozzle 21 when the binder droplets are continuously ejected becomes unstable. In other words, when the inertance ratio between the second nozzle 21b and the first nozzle 21a becomes large, the meniscus of the binder does not remain within the first nozzle 21a but moves into the second nozzle 21b, making it impossible to continuously eject binder droplets stably.

[0051] Moreover, if the inner diameter of the second nozzle 21b is made too small, the flow of the binder in the second nozzle 21b during circulation becomes difficult. Moreover, if the inner diameter of the second nozzle 21b is made too small, the flow resistance from the pressure chamber 12 to the nozzle 21 increases, and the pressure loss increases, so that the weight of the binder droplets discharged from the nozzle 21 becomes small. Therefore, the piezoelectric actuator 300 must be driven with a higher driving voltage, and the discharge efficiency decreases. Therefore, the size of the first nozzle 21a and the second nozzle 21b is appropriately determined in consideration of the replacement performance of the binder during circulation, the discharge stability, the discharge efficiency, the flying speed of the binder, and the like.

[0052] The first nozzle 21a and the second nozzle 21b are provided so that the opening shapes are substantially the same along the Z-axis direction. As a result, a step is formed between the first nozzle 21a and the second nozzle 21b. Of course, the shapes of the first nozzle 21a and the second nozzle 21b are not limited to this, and for example, the inner surface of the second nozzle 21b may be an inclined surface inclined with respect to the Z-axis direction. That is, the inner diameter of the second nozzle 21b may be provided so as to gradually decrease toward the first nozzle 21a. As a result, for example, no step is formed between the first nozzle 21a and the second nozzle 21b, and the inner surface may be continuous. In this way, when the inner surfaces of the first nozzle 21a and the second nozzle 21b are continuous, the first nozzle 21a refers to a portion whose opening shape is substantially the same along the Z-axis direction.

[0053] Furthermore, the shape of the nozzle 21 when viewed in a plan view from the Z-axis direction is not particularly limited, and may be circular, elliptical, rectangular, polygonal, potbellied, or the like.

[0054] Such a nozzle plate 20 can be formed of, for example, a metal such as stainless steel (SUS), an organic material such as polyimide resin, or a flat plate-like member such as silicon. The thickness of the nozzle plate 20 is preferably 60 μm or more and 100 μm or less. By using a nozzle plate 20 with such a thickness, the handleability of the nozzle plate 20 can be improved, and the assemblyability of the discharge head 100 can be improved. Incidentally, by shortening the length of the nozzle 21 in the Z-axis direction, when the binder is circulated, the part in the nozzle 21 that is not affected by the circulation flow can be made smaller, but in order to shorten the length of the nozzle 21 in the Z-axis direction, it is necessary to reduce the thickness of the nozzle plate 20 in the Z-axis direction. If the thickness of the nozzle plate 20 is reduced in this way, the rigidity of the nozzle plate 20 decreases, and the nozzle plate 20 is likely to deform to cause variations in the discharge direction of the binder droplets, or the nozzle plate 20 is likely to be less easy to assemble due to its poor handleability. In other words, by using a nozzle plate 20 having a certain degree of thickness as described above, it is possible to suppress a decrease in the rigidity of the nozzle plate 20, thereby suppressing variations in the ejection direction caused by deformation of the nozzle plate 20 and a decrease in assembly ease caused by reduced handleability.

[0055] In this embodiment, the communicating plate 15 has a first communicating plate 151 and a second communicating plate 152. The first communicating plate 151 and the second communicating plate 152 are stacked in the Z axis direction such that the first communicating plate 151 is on the -Z side and the second communicating plate 152 is on the +Z side.

[0056] The first communication plate 151 and the second communication plate 152 constituting the communication plate 15 can be manufactured from a metal such as stainless steel, glass, a ceramic material, etc. The communication plate 15 is preferably made of a material having substantially the same thermal expansion coefficient as the flow path forming substrate 10, and in this embodiment, the communication plate 15 is formed using a silicon single crystal substrate which is the same material as the flow path forming substrate 10.

[0057] The communicating plate 15 is provided with a first communicating portion 16 that communicates with the first liquid chamber portion 41 of the case member 40 and constitutes a part of the first common liquid chamber 101, and a second communicating portion 17 and a third communicating portion 18 that communicate with the second liquid chamber portion 42 of the case member 40 and constitute a part of the second common liquid chamber 102. The communicating plate 15 is further provided with a flow path that communicates the first common liquid chamber 101 with the pressure chamber 12, a flow path that communicates the pressure chamber 12 with the nozzle 21, and a flow path that communicates the nozzle 21 with the second common liquid chamber 102, which will be described in detail later. These flow paths provided in the communicating plate 15 constitute a part of the individual flow paths 200A.

[0058] The first communication portion 16 is provided at a position overlapping the first liquid chamber portion 41 of the case member 40 in the Z-axis direction, and is provided penetrating the communication plate 15 in the Z-axis direction so as to open to both the +Z side surface and the Z side surface of the communication plate 15. The first communication portion 16 is connected to the first liquid chamber portion 41 on the -Z side to form a first common liquid chamber 101. That is, the first common liquid chamber 101 is formed by the first liquid chamber portion 41 of the case member 40 and the first communication portion 16 of the communication plate 15. The first communication portion 16 is also extended in the -Y-axis direction to a position overlapping the pressure chamber 12 in the Z-axis direction on the +Z side. The first communication portion 16 may not be provided in the communication plate 15, and the first common liquid chamber 101 may be formed by the first liquid chamber portion 41 of the case member 40.

[0059] The second communication portion 17 is provided at a position overlapping with the second liquid chamber portion 42 of the case member 40 in the Z-axis direction, and is provided to open on the -Z side surface of the first communication plate 151. In addition, the second communication portion 17 is provided on the +Z side with a wider width toward the nozzle 21 in the +Y-axis direction.

[0060] The third communication portion 18 is provided penetrating the second communication plate 152 in the Z-axis direction so that one end communicates with a portion of the second communication portion 17 that is widened toward the +Y-axis direction. The opening on the +Z side of the third communication portion 18 is covered by the nozzle plate 20. That is, by providing the second communication portion 17 on the first communication plate 151, only the opening on the +Z side of the third communication portion 18 can be covered by the nozzle plate 20, so that the nozzle plate 20 can be provided in a relatively small area, and costs can be reduced.

[0061] The second common liquid chamber 102 is formed by the second communicating portion 17 and the third communicating portion 18 provided in the communicating plate 15 and the second liquid chamber portion 42 provided in the case member 40. The second common liquid chamber 102 may be formed by the second liquid chamber portion 42 of the case member 40 without providing the second communicating portion 17 and the third communicating portion 18 in the communicating plate 15.

[0062] A compliance substrate 49 having a compliance portion 494 is provided on the +Z side surface of the communication plate 15 where the first communication portion 16 opens. This compliance substrate 49 seals the opening of the first common liquid chamber 101 on the nozzle surface 20a side.

[0063] In this embodiment, the compliance substrate 49 includes a sealing film 491 made of a flexible thin film, and a fixed substrate 492 made of a hard material such as metal. The region of the fixed substrate 492 facing the first common liquid chamber 101 is an opening 493 that is completely removed in the thickness direction, and therefore a part of the wall surface of the first common liquid chamber 101 is a compliance section 494 that is a flexible section sealed only by the flexible sealing film 491. By providing the compliance section 494 on a part of the wall surface of the first common liquid chamber 101 in this manner, pressure fluctuations of the binder in the first common liquid chamber 101 can be absorbed by deformation of the compliance section 494.

[0064] Furthermore, a pressure sensor 400 that detects the pressure inside the first common liquid chamber 101 is provided on the -Z axis side of the compliance portion 494. This pressure sensor 400 is electrically connected to the control unit 700, and information regarding the pressure inside the first common liquid chamber 101 detected by the pressure sensor 400 is transmitted to the control unit 700.

[0065] Further, the flow path forming substrate 10, the communication plate 15, the nozzle plate 20, the compliance substrate 49, etc., which constitute the flow path substrate, are provided with a plurality of individual flow paths 200A which communicate with the first common liquid chamber 101 and the second common liquid chamber 102 and send the binder in the first common liquid chamber 101 to the second common liquid chamber 102. Here, in this embodiment, each individual flow path 200A communicates with the first common liquid chamber 101 and the second common liquid chamber 102 and is provided for each nozzle 21, and includes the nozzle 21. Such a plurality of individual flow paths 200A are arranged in parallel along the X-axis direction, which is the direction in which the nozzles 21 are arranged in parallel. Two individual flow paths 200A adjacent to each other in the X-axis direction, which is the direction in which the nozzles 21 are arranged in parallel, are arranged in communication with the first common liquid chamber 101 and the second common liquid chamber 102, respectively. That is, the multiple individual flow paths 200A provided for each nozzle 21 are provided so as to communicate only with each other via the first common liquid chamber 101 and the second common liquid chamber 102, and the multiple individual flow paths 200A do not communicate with each other except through the first common liquid chamber 101 and the second common liquid chamber 102. That is, in this embodiment, a flow path in which one nozzle 21 and one pressure chamber 12 are provided is referred to as an individual flow path 200A, and the individual flow paths 200A are provided so as to communicate with each other only via the first common liquid chamber 101 and the second common liquid chamber 102.

[0066] As shown in FIG. 3, the individual flow path 200A is composed of the nozzle 21, the pressure chamber 12, a first flow path 201A, a second flow path 202A, and a supply path 203A.

[0067] As described above, the pressure chamber 12 is provided between the recess provided in the flow path forming substrate 10 and the communication plate 15, and extends in the Y-axis direction. That is, the supply channel 203A is connected to one end of the pressure chamber 12 in the Y-axis direction, and the second channel 202A is connected to the other end of the pressure chamber 12 in the Y-axis direction, and the binder flows in the Y-axis direction inside the pressure chamber 12. In other words, the extension direction of the pressure chamber 12 is the direction in which the binder flows inside the pressure chamber 12.

[0068] In this embodiment, only the pressure chamber 12 is formed in the flow path forming substrate 10, but this is not limited to this, and a flow path resistance imparting portion having a smaller cross-sectional area than the pressure chamber 12 may be provided at the upstream end of the pressure chamber 12, i.e., the end in the +Y axis direction, so as to impart flow path resistance.

[0069] The supply path 203A connects the pressure chamber 12 and the first common liquid chamber 101, and is provided penetrating the first communication plate 151 in the Z-axis direction. The supply path 203A communicates with the first common liquid chamber 101 at its end on the +Z side, and communicates with the pressure chamber 12 at its end on the -Z side. In other words, the supply path 203A extends in the Z-axis direction. Here, the extension direction of the supply path 203A refers to the direction in which the binder flows inside the supply path 203A.

[0070] The first flow path 201A is provided between the supply port 43 and the discharge port 44, extending in the Y-axis direction. The direction in which the first flow path 201A extends is the direction in which the binder flows through the first flow path 201A. That is, the first axis direction in which the first flow path 201A extends is the Y-axis direction in this embodiment. The first flow path 201A communicates with the second flow path 202A at an end in the +Y-axis direction, and communicates with the third communication part 18 of the second common liquid chamber 102 at an end in the -Y-axis direction.

[0071] The first flow path 201A in this embodiment is provided between the second communication plate 152 and the nozzle plate 20, extending along the Y-axis direction. Specifically, the first flow path 201A is formed by providing a recess in the second communication plate 152 and covering the opening of this recess with the nozzle plate 20. Note that the first flow path 201A is not particularly limited to this, and a recess may be provided in the nozzle plate 20 and the recess of the nozzle plate 20 may be covered by the second communication plate 152, or recesses may be provided in both the second communication plate 152 and the nozzle plate 20.

[0072] In this embodiment, the first flow path 201A is provided so that the cross-sectional area crossing the binder flowing through the flow path, i.e., the cross-sectional area in the planar direction including the X-axis direction and the Z-axis direction, is the same area along the Y-axis direction. The first flow path 201A may be provided so that the cross-sectional area varies along the Y-axis direction. The difference in the area crossing the first flow path 201A includes the case where the height in the Z-axis direction is different, the case where the width in the X-axis direction is different, or the case where both are different.

[0073] The cross-sectional shape of first flow path 201A across the flow path, i.e., the cross-sectional shape in a plane direction including the X-axis direction and the Z-axis direction, is rectangular. The cross-sectional shape of first flow path 201A across the flow path is not particularly limited, and may be a trapezoid, a semicircle, a semiellipse, or the like.

[0074] The second flow path 202A is provided between the pressure chamber 12 and the first flow path 201A, extending in the Z-axis direction. The direction in which the second flow path 202A extends is the direction in which the binder flows through the second flow path 202A. That is, in this embodiment, the direction in which the second flow path 202A extends is the Z-axis direction, which is the same as the second axis direction. In this embodiment, the second flow path 202A is provided penetrating the communication plate 15 in the Z-axis direction, and communicates with the pressure chamber 12 at the end in the -Z-axis direction and with the first flow path 201A at the end in the +Z-axis direction.

[0075] The second flow path 202A refers to a portion formed in the communication plate 15. That is, the second flow path 202A extends from the bottom surface of the pressure chamber 12 in the +Z-axis direction to the portion that is covered by the nozzle plate 20.

[0076] The nozzle 21 is disposed at a position communicating with the first flow path 201A. That is, the nozzle 21 is provided branching off from the first flow path 201A extending in the Y-axis direction in the +Z-axis direction. This allows the nozzle 21 to jet binder droplets in the +Z-axis direction. That is, the nozzle 21 is provided penetrating the nozzle plate 20 in the Z-axis direction so that the end in the -Z-axis direction is communicating with the first flow path 201A and the end in the +Z-axis direction is open to the nozzle surface 20a of the nozzle plate 20. Therefore, the second axis direction in which the nozzle 21 jets binder droplets is the Z-axis direction.

[0077] Here, the nozzle 21 being branched off from the first flow path 201A means that the nozzle 21 is connected to the middle of the first flow path 201A. And the nozzle 21 being connected to the middle of the first flow path 201A means that the nozzle 21 is arranged at a position overlapping the first flow path 201A when viewed in a plan view from the Z axis direction. Incidentally, the nozzle 21 being arranged at a position overlapping the second flow path 202A when viewed in a plan view from the Z axis direction is not said to be arranged to be connected to the middle of the first flow path 201A. In other words, the first flow path 201A of this embodiment is a portion that does not overlap the second flow path 202A when viewed in a plan view from the Z axis direction.

[0078] In addition, the cross-sectional area of ​​the binder flowing through the first flow path 201A to which the nozzle 21 is connected is preferably smaller than the cross-sectional area of ​​the binder flowing through the second flow path 202A. In addition, the cross-sectional area of ​​the first flow path 201A is the area of ​​the cross section in the planar direction including the X-axis direction and the Z-axis direction. In addition, the cross-sectional area of ​​the second flow path 202A is the area of ​​the cross section in the planar direction including the Y-axis direction and the Z-axis direction. By making the cross-sectional area of ​​the first flow path 201A relatively small in this way, the individual flow paths 200A can be densely arranged in the X-axis direction, and the nozzles 21 can be densely arranged in the X-axis direction, and the ejection head 100 can be prevented from becoming large in the Z-axis direction. In addition, by making the cross-sectional area of ​​the second flow path 202A relatively large, the flow path resistance from the pressure chamber 12 to the nozzle 21 can be prevented from becoming small, and the ejection characteristics of the binder, particularly the weight of the ejected droplets, can be prevented from decreasing. In particular, by widening the second flow path 202A in the Y-axis direction and increasing the cross-sectional area of ​​the second flow path 202A, the flow path resistance of the second flow path 202A can be reduced and the individual flow paths 200A can be prevented from being arranged at a low density, thereby enabling the individual flow paths 200A to be arranged at a high density.

[0079] In such an individual flow path 200A, the binder flows from the first common liquid chamber 101 through the individual flow path 200A to the second common liquid chamber 102. In addition, by driving the piezoelectric actuator 300, a pressure change is generated in the binder in the pressure chamber 12, and the pressure of the binder in the nozzle 21 is increased, so that a binder droplet is ejected from the nozzle 21 to the outside in the +Z axis direction. The piezoelectric actuator 300 may be driven when the binder flows from the first common liquid chamber 101 through the individual flow path 200A to the second common liquid chamber 102, or the piezoelectric actuator 300 may be driven when the binder does not flow from the first common liquid chamber 101 through the individual flow path 200A to the second common liquid chamber 102. In addition, a pressure change caused by driving the piezoelectric actuator 300 may temporarily cause the binder to flow from the second common liquid chamber 102 to the first common liquid chamber 101.

[0080] Each component of the 3D modeling apparatus 1 is electrically connected to a control unit 700 (described later), which controls the operation of each component.

[0081] As described above, the inflow channel 300A is formed by the first common liquid chamber 101 and the supply channel 203A, and the outflow channel 300B is formed by the first channel 201A, the second channel 202A, and the second common liquid chamber 102. The three-dimensional modeling apparatus 1 includes a circulation channel 300C that circulates the binder flowing out from the outflow channel 300B to 300A. In the configuration shown in FIG. 1, the circulation channel 300C includes the discharge channel 241, the binder path 282, the binder path 284, the binder path 281, and the supply channel 231. By including such a circulation channel 300C, the binder not discharged from the nozzle 21 is configured to circulate from the pressure chamber 12 through the outflow channel 300B, the circulation channel 300C, and the inflow channel 300A in this order, and return to the pressure chamber 12 again. This configuration provides the following advantages.

[0082] In the binder jet method, the density of the molded object tends to be relatively low compared to other methods. For this reason, it is preferable to reduce the amount of water-soluble resin and wetting agent contained in the binder. However, simply reducing the amount of wetting agent reduces the ejection stability. Therefore, as described above, by circulating the binder, ejection stability can be improved even if the content of the wetting agent is reduced, and the density of the molded object can be increased.

[0083] In the above, the circulation flow path 300C has been described as including the discharge flow path 241, the binder path 282, the binder path 284, the binder path 281, and the supply flow path 231. However, the present invention is not limited to this configuration. For example, when the first manifold 230 and the second manifold 240 are connected, the discharge flow path 241, the supply flow path 231, and the flow paths connecting the first manifold 230 and the second manifold 240 constitute the circulation flow path 300C.

[0084] Furthermore, the ratio R1 / R2 of the flow rate R1 per unit time of the binder discharged from the nozzle 21 to the flow rate R2 per unit time of the binder circulating without being discharged from the nozzle 21, i.e., flowing out to the outflow channel 300B, is preferably 0.05 to 20, more preferably 0.1 to 1. This can further improve the discharge stability of the binder.

[0085] As shown in FIG. 4, a plurality of such discharge heads 100 are provided, and each discharge head 100 is collectively supported by a carriage 500. The carriage 500 may be configured to be movable in the X-axis direction or the Y-axis direction. In addition, a heater 600 is provided for each discharge head 100 on the carriage 500. The heater 600 has a function of drying the binder. The heater 600 is electrically connected to a control unit 700, and the operation is controlled by controlling the energization conditions by the control unit 700. For example, by repeating the operation of discharging the binder onto a table (not shown) and drying it, a plurality of layers can be stacked to obtain a three-dimensional object.

[0086] In this manner, the three-dimensional modeling apparatus 1 includes the discharge head 100, the heater 600 for drying the binder, and the carriage 500 for supporting it. This allows the binder discharged by the discharge head 100 to be dried satisfactorily. This improves the moldability of the modeled object and simplifies the device configuration. In addition, since only the necessary parts of the discharged binder can be dried, the undried binder can be recycled.

[0087] The configuration is not limited to the above, and the heater 600 may be provided on the table side.

[0088] The control unit 700 has a function of controlling each part of the three-dimensional printing apparatus 1. The control unit 700 is composed of, for example, a computer, and has at least one processor (e.g., CPU) that processes information, a memory (e.g., ROM, RAM) communicatively connected to the processor, and an external interface that connects to an external device. Various programs executable by the processor are stored in the memory, and the processor can read and execute the various programs stored in the memory. Some or all of the components of the control unit 700 may be disposed outside the housing of the three-dimensional printing apparatus 1.

[0089] In addition, a pressure threshold value is stored in the memory of the control unit 700. During modeling, the processor acquires information on the pressure in the first common liquid chamber 101 based on the detection result detected by the pressure sensor 400, and determines whether the pressure exceeds the threshold value. If the processor determines that the pressure in the first common liquid chamber 101 exceeds the threshold value, it adjusts the operation of the vacuum pump 215 shown in FIG. 1 to adjust the pressure in the first common liquid chamber 101.

[0090] Specifically, the processor normally operates the vacuum pump 215 under predetermined conditions, and when the pressure inside the first common liquid chamber 101 is lower than a threshold value, changes the energization conditions for the vacuum pump 215 so as to reduce the liquid sending speed, i.e., the circulation speed, compared to normal times. Note that the energization conditions when the pressure inside the first common liquid chamber 101 exceeds the threshold value are also stored in advance in the memory.

[0091] In this embodiment, the pressure sensor 400 is described as being arranged in the inlet flow path 300A, but the present invention is not limited to this, and the pressure sensor 400 may be arranged in any of the pressure chamber 12, the outlet flow path 300B, and the circulation flow path 300C.

[0092] Thus, the three-dimensional modeling apparatus 1 includes a pressure sensor 400 that detects the pressure in at least one of the pressure chamber 12, which is an individual liquid chamber, the inflow path 300A, the outflow path 300B, and the circulation path 300C, and a control unit 700 that adjusts the circulation speed of the binder based on the detection result of the pressure sensor 400. This makes it possible, for example, to keep the circulation speed of the binder as constant as possible, and further improve the ejection stability of the binder.

[0093] Furthermore, when the pressure is lower than the threshold value, the control unit 700 controls the operation of the vacuum pump 215 to increase the circulation speed of the binder. This makes it possible to keep the pressure as constant as possible by increasing the circulation speed even if the pressure drops. As a result, it is possible to further improve the ejection stability of the binder.

[0094] Next, the binder discharged from the nozzle 21 will be described. As previously mentioned, the binder includes water, a water-soluble resin, and a wetting agent.

[0095] By including a water-soluble resin in the binder, it is possible to prevent or suppress deformation of a shaped object obtained by discharging the binder when the shaped object is sintered.

[0096] Examples of the water-soluble resin include polyvinyl alcohol resin, polyacrylic acid resin, cellulose resin, starch, gelatin, vinyl resin, amide resin, imide resin, acrylic resin, polyethylene glycol, etc. As long as they are water-soluble, they may be homopolymers or heteropolymers, may be modified, may have known functional groups introduced therein, or may be in the form of a salt. By using such a water-soluble resin, it is possible to effectively prevent or suppress the deformation of the resulting shaped object.

[0097] Examples of the polyvinyl alcohol resin include polyvinyl alcohol, acetoacetyl group, acetyl group, polyvinyl alcohol modified with silicone or the like, and butanediol-vinyl alcohol copolymer.

[0098] The polyacrylic acid resin may be, for example, polyacrylic acid or a salt such as sodium polyacrylate.

[0099] The cellulose resin may be, for example, cellulose or carboxymethyl cellulose.

[0100] Examples of the acrylic resin include polyacrylic acid, acrylic acid-maleic anhydride copolymer, and the like.

[0101] Next, the wetting agent will be described. The wetting agent has a function of suppressing drying inside the nozzle 21. The wetting agent is preferably an organic solvent having a bp of 200 degrees or more.

[0102] The wetting agent is not particularly limited as long as it has the above-mentioned function, and examples thereof include alcohols such as ethanol, propanol, and butanol, ethers, and ketones.Specific examples thereof include 2-butoxyethanol, 1,2,6-hexanetriol, 1,2-butanediol, 1,2-hexanediol, 2-pentanediol, 1,3-dimethyl-2-imidazolidinone, 1,3-butanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 2,3-butanediol, 2,4-Pentanediol, 2,5-Hexanediol, 2-Ethyl-1,3-Hexanediol, 2-Pyrrolidone, 2-Methyl-1,3-Propanediol, 2-Methyl-2,4-Pentanediol, 3-Methyl-1,3-Butanediol, 3-Methyl-1,3-Hexanediol, N-Methyl-2-Pyrrolidone, N-Methylpyrrolidinone, β-Butoxy-N,N-Dimethylpropionamide, β-Methoxy-N,N-Dimethylpropionamide, γ-butyrolactone, ε-caprolactam, ethylene glycol, ethylene glycol-n-butyl ether, ethylene glycol-n-propyl ether, ethylene glycol phenyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monoethyl ether, glycerin, diethylene glycol, diethylene glycol-n-hexyl ether, diethylene glycol methyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diglycerin, dipropylene glycol, dipropylene glycol n-propyl ether, dipropylene glycol monomethyl ether, dimethyl sulfoxide, sulfolane, thiodiglycol, tetraethylene glycol Examples of the propylene glycol include propylene glycol, triethylene glycol ethyl ether, triethylene glycol dimethyl ether, triethylene glycol monobutyl ether, triethylene glycol methyl ether, tripropylene glycol, tripropylene glycol-n-propyl ether, tripropylene glycol methyl ether, trimethylolethane, trimethylolpropane, propyl propylene diglycol, propylene glycol, propylene glycol-n-butyl ether, propylene glycol-t-butyl ether, propylene glycol phenyl ether, propylene glycol monoethyl ether, hexylene glycol, polyethylene glycol, and polypropylene glycol. These may be used alone or in combination of two or more.

[0103] Among these, the wetting agent is preferably an aliphatic diol such as ethylene glycol, 1,4-butanediol, 1,3-propanediol, 2-butoxyethanol, propylene glycol, triethylene glycol, 2-pyrrolidone, etc. This makes it possible to more reliably prevent the inside of the nozzle 21 from drying out, and also makes it possible to achieve the above-mentioned effect with a relatively small amount.

[0104] The content of the wetting agent in the binder is preferably 5% by weight or less, and more preferably 4% by weight or less, based on the weight of the binder, which can reliably increase the discharge stability of the binder and sufficiently increase the density of the molded object.

[0105] As described above, the three-dimensional modeling apparatus 1 includes a nozzle 21 that ejects a binder containing water, a water-soluble resin, and a wetting agent, a pressure chamber 12 that is an individual liquid chamber that communicates with the nozzle 21, an ejection head 100 having an inflow channel 300A that allows the binder to flow into the pressure chamber 12, and an outflow channel 300B that allows the binder to flow out from the pressure chamber 12, and a circulation channel 300C that circulates the binder that has flowed out from the outflow channel 300B to the inflow channel 300A. The binder that has not been ejected from the nozzle 21 can be circulated from the pressure chamber 12 through the outflow channel 300B, the circulation channel 300C, and the inflow channel 300A in this order, and returned to the pressure chamber 12 again. In the binder jet method, the density of the modeled object tends to be relatively low compared to other methods. For this reason, it is preferable to reduce the amount of water-soluble resin and wetting agent contained in the binder. However, simply reducing the amount of wetting agent reduces ejection stability. Therefore, as described above, by circulating the binder, it is possible to improve the discharge stability even if the content of the wetting agent in the binder is reduced, and it is possible to increase the density of the shaped object. EXAMPLES

[0106] Next, specific examples of the present invention will be described. 。

[0107] Example 2 A binder was loaded into the three-dimensional modeling apparatus shown in Figures 1 to 4, and the binder was discharged to obtain a model. The binder used contained water, a water-soluble resin, and a wetting agent. The water-soluble resin was polyvinyl alcohol. (PVA)The binder contained 98.7% by mass of water, 0.8% by mass of water-soluble resin, and 0.5% by mass of wetting agent.

[0108] (Example 3- Example 6, Example 8 Example 18) The binder was discharged in the same manner as in Example 2, except that the contents of water, water-soluble resin, and wetting agent were as shown in Table 1.

[0109] Comparative Example 1 A binder was loaded into a conventional three-dimensional modeling device that does not have a circulation flow path, and the binder was discharged to obtain a model. The binder used contained water and a water-soluble resin, and the water-soluble resin was polyvinyl alcohol. The water content in the binder was 99.2% by mass, and the water-soluble resin content in the binder was 0.8% by mass.

[0110] Comparative Example 2 A binder was loaded into a conventional three-dimensional modeling device that does not have a circulation flow path, and the binder was discharged to obtain a model. The binder used contained water, a water-soluble resin, and a wetting agent, and the water-soluble resin was polyvinyl alcohol, and the wetting agent was 2-butoxyethanol. The water content in the binder was 98.7% by mass, the water-soluble resin content in the binder was 0.8% by mass, and the wetting agent content in the binder was 0.5% by mass.

[0111] (Comparative Example 3 to Comparative Example 18) The binder was discharged in the same manner as in Comparative Example 2, except that the contents of water, water-soluble resin and wetting agent were as shown in Table 2.

[0112] (Example 19) As shown in Table 3, a binder was loaded into the three-dimensional modeling apparatus shown in Figures 1 to 4, and the binder was discharged to obtain a modeled object. The binder used contained water, a water-soluble resin, and a wetting agent, and the water-soluble resin was polyvinylpyrrolidone, and the wetting agent was 2-butoxyethanol. The water content in the binder was 97.8% by mass, the water-soluble resin content in the binder was 0.2% by mass, and the wetting agent content in the binder was 2.0% by mass.

[0113] (Examples 20 to 24) The binder was discharged in the same manner as in Example 2, except that the contents of water, water-soluble resin, and wetting agent were as shown in Table 3.

[0114] Comparative Example 19 A binder was loaded into a conventional three-dimensional modeling device that does not have a circulation flow path, and the binder was discharged to obtain a model. The binder used contained water, a water-soluble resin, and a wetting agent, and the water-soluble resin was polyvinylpyrrolidone, and the wetting agent was 2-butoxyethanol. The water content in the binder was 97.8% by mass, the water-soluble resin content in the binder was 0.2% by mass, and the wetting agent content in the binder was 2.0% by mass.

[0115] (Comparative Examples 20 to 24) The binder was discharged in the same manner as in Comparative Example 19, except that the contents of water, water-soluble resin and wetting agent were as shown in Table 4.

[0116] <Evaluation> 1.Discharge stability The amount of binder discharged from the discharge nozzle per unit time was measured, and the results were evaluated as follows. A: The discharge weight is 98% or more of the target value. B: The discharge weight is 95% or more but less than 98% of the target value. C: The discharge weight is 90% or more but less than 95% of the target value. D: The discharge weight is less than 90% of the target value. E: Visually check that no binder is being discharged from the discharge nozzle.

[0117] 2. Density of the object A: The weight of the sintered object is 60% or more of the weight of the object before sintering. B: The weight of the sintered object is 55% or more and less than 60% of the weight of the object before sintering. C: The weight of the sintered object is 50% or more and less than 55% of the weight of the object before sintering. D: The weight of the sintered object is 45% or more and less than 50% of the weight of the object before sintering. E: The weight of the sintered object is less than 45% of the weight of the object before sintering.

[0118] The configurations and evaluation results of the objects obtained in each of the Examples and Comparative Examples are shown in Tables 1 to 4. In the tables, "-" indicates that the object collapsed and could not be produced.

[0119] [Table 1]

[0120] [Table 2]

[0121] [Table 3]

[0122] [Table 4]

[0123] As is clear from Tables 1 to 4, the three-dimensional printing apparatus (each Comparative Example) not equipped with the circulation flow path 300C had poor binder discharge stability. In addition, the objects produced by the three-dimensional printing apparatus (each Comparative Example) not equipped with the circulation flow path 300C had low density or the objects collapsed, making it impossible to measure the density. In contrast, the three-dimensional printing apparatus (each Example) equipped with the circulation flow path 300C had excellent binder discharge stability. In addition, the densities of the objects produced were also high, resulting in satisfactory results.

[0124] Although the three-dimensional printing apparatus of the present invention has been described above with reference to the illustrated embodiment, the present invention is not limited thereto. Furthermore, each component constituting the three-dimensional printing apparatus can be replaced with any component capable of performing the same function. Furthermore, any component may be added. [Explanation of symbols]

[0125] Reference Signs List 1...three-dimensional modeling device, 10...flow path forming substrate, 12...pressure chamber, 15...communicating plate, 16...first communicating portion, 17...second communicating portion, 18...third communicating portion, 20...nozzle plate, 20a...nozzle surface, 21...nozzle, 21a...first nozzle, 21b...second nozzle, 22...nozzle row, 30...protective substrate, 31...piezoelectric actuator holding portion, 32...through hole, 40...case member, 41...first liquid chamber portion, 42...second liquid chamber portion, 43...supply port, 44...exhaust port, 45...connection port, 60...first electrode, 70...piezoelectric layer, 80...second electrode, 90 ...lead electrode, 100...ejection head, 101...first common liquid chamber, 102...second common liquid chamber, 120...flexible cable, 121...drive circuit, 151...first communication plate, 152...second communication plate, 200A...individual flow path, 201...main tank, 201A...first flow path, 202...first liquid feed pump, 202A...second flow path, 203...second liquid feed pump, 203A...supply path, 206...first adjustment device, 207...second adjustment device, 210...pressure reducing sub-tank, 210a...gas chamber, 211...liquid level detection means, 212...solenoid valve, 213... Regulator, 214...decompression buffer tank, 215...vacuum pump, 216...solenoid valve, 217...solenoid valve, 220...pressurized sub-tank, 220a...gas chamber, 221...liquid level detection means, 222...solenoid valve, 223...regulator, 224...pressurized buffer tank, 225...compressor, 226...solenoid valve, 227...solenoid valve, 230...first manifold, 231...supply flow path, 232...solenoid valve, 233...pressure sensor, 240...second manifold, 241...discharge flow path, 242...solenoid valve, 243...pressure sensor, 251...head tank, 252...head tank, 260...deaerator, 261...filter, 281...binder path, 282...binder path, 284...binder path, 289...binder path, 300...piezoelectric actuator, 300A...inlet flow path, 300B...outlet flow path, 300C...circulation flow path, 301...circulation path, 400...pressure sensor, 491...sealing film, 492...fixed substrate, 493...opening, 494(49)...compliance section, 500...carriage, 600...heater, 700...control section

Claims

1. a discharge head including: a nozzle for discharging a binder containing water, a water-soluble resin, and a wetting agent; an individual liquid chamber communicating with the nozzle; an inflow flow path for causing the binder to flow into the individual liquid chamber; and an outflow flow path for causing the binder to flow out of the individual liquid chamber; a circulation flow path that circulates the binder that has flowed out from the outlet flow path to the inlet flow path, a decompression sub-tank for reducing the pressure, a degassing device for removing gas from the binder, and a pressurization sub-tank for increasing the pressure are disposed in the circulation flow path in the following order along a flow direction of the circulation flow path: the decompression sub-tank, the degassing device, and the pressurization sub-tank; a main tank that stores the binder and supplies the binder to the reduced pressure sub-tank; a ratio R1 / R2 of a flow rate per unit time R1 of the binder ejected from the nozzle to a flow rate per unit time R2 of the binder that is not ejected from the nozzle but flows out from the individual liquid chamber to the outflow flow path and circulates, is 0.1 or more and 1 or less.

2. The three-dimensional modeling apparatus according to claim 1 , wherein the content of the wetting agent in the binder is 5% by weight or less with respect to the weight of the binder.

3. The three-dimensional modeling apparatus according to claim 1 , wherein the wetting agent includes an aliphatic diol.

4. 4. The three-dimensional modeling apparatus according to claim 1, wherein the water-soluble resin is at least one selected from the group consisting of polyvinyl alcohol resin, polyacrylic acid resin, cellulose resin, starch, gelatin, vinyl resin, amide resin, imide resin, acrylic resin, and polyethylene glycol.

5. The three-dimensional modeling apparatus according to claim 1 , further comprising a carriage supporting the discharge head and a heater for drying the binder.

6. a pressure sensor for detecting a pressure in at least one of the individual liquid chambers, the inflow passage, the outflow passage, and the circulation passage; The three-dimensional modeling apparatus according to claim 1 , further comprising: a control unit that adjusts a circulation speed of the binder based on a detection result of the pressure sensor.

7. The three-dimensional modeling apparatus according to claim 6 , wherein the control unit increases a circulation speed of the binder when the pressure is lower than a threshold value.

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