Additive manufacturing apparatus and method for manufacturing three-dimensional structures

Abstract

The present invention provides an additive manufacturing apparatus and a method for manufacturing three-dimensional structures that can produce higher quality three-dimensional structures. [Solution] The additive manufacturing apparatus according to the present disclosure comprises a nozzle section 10 having a resin discharge port 11 for discharging molten resin F, and a cylindrical cooling section 20 provided so as to surround the nozzle section 10, wherein the cooling section 20 comprises a gas injection port 21 for injecting gas AR into the resin F discharged from the resin discharge port 11, and a gas flow path 22 for guiding the gas AR to the gas injection port 21, wherein a plurality of gas injection ports 21 are arranged near the resin discharge port 11 so as to surround the resin discharge port 11, and the gas flow path 22 comprises a main flow path 221 concentric with the resin discharge port 11, and branch flow paths 222 that branch the gas AR flowing through the main flow path 221 into a plurality of branches and guide the gas AR diagonally downward toward the gas injection port 21.

Description

Technical Field

[0001] The present disclosure relates to a laminated manufacturing apparatus and a three-dimensional structure manufacturing method.

Background Art

[0002] There has been proposed a laminated manufacturing apparatus, that is, a 3D printer, which manufactures a three-dimensional structure by stacking layers of melted resin. The stacked resin solidifies due to a temperature drop, and a three-dimensional structure is completed. However, due to variations in the shrinkage rate of the resin accompanying the temperature drop during solidification, warping or defects may occur in the three-dimensional structure. For example, in Patent Document 1, gas is injected from an air duct into the resin, and the resin is cooled and solidified to suppress the occurrence of warping or defects in the three-dimensional structure.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Regarding the laminated manufacturing apparatus disclosed in Patent Document 1, the inventor has found the following problems. Cooling of the resin by a cooling unit such as a commercially available air duct or fan as shown in Patent Document 1 cools the resin other than the resin immediately after ejection globally for cooling the three-dimensional structure, which may cause overcooling and lead to a decrease in tensile strength. In addition, due to space constraints around the laminated manufacturing apparatus, many cooling units cannot be arranged, and there may be a location where gas does not hit depending on the direction of the resin, resulting in a portion that cannot be sufficiently cooled, and there is a risk of shape collapse of the three-dimensional structure.

[0005] The present invention has been made to solve such problems, and an object thereof is to provide a laminated manufacturing apparatus and a three-dimensional structure manufacturing method capable of manufacturing a higher-quality three-dimensional structure. [Means for solving the problem]

[0006] The additive manufacturing apparatus according to the present disclosure comprises a nozzle section having a resin discharge port for discharging molten resin, and a cylindrical cooling section provided so as to surround the nozzle section, wherein the cooling section comprises a gas injection port for injecting gas into the resin discharged from the resin discharge port, and a gas flow path for guiding the gas to the gas injection port, wherein a plurality of gas injection ports are arranged near the resin discharge port so as to surround the resin discharge port, and the gas flow path comprises a main flow path concentric with the resin discharge port, and branch flow paths that branch the gas flowing through the main flow path into a plurality of branches and guide the gas diagonally downward toward the gas injection port.

[0007] As a result, the resin discharged from the nozzle is subjected to gas injection from multiple angles. Therefore, deformation of the three-dimensional structure due to insufficient cooling of the resin can be suppressed.

[0008] The resin discharge port, when discharging the resin, may be located above the resin with respect to the position of the gas injection port.

[0009] The cooling unit may inject the gas into the resin so as to cool the resin discharged from the resin discharge port to a temperature below the glass transition temperature.

[0010] The cooling unit further comprises a refrigerant channel through which a refrigerant flows for temperature adjustment of the cooling unit, and after the resin is discharged, the cooling unit may be pressed against the laminated resin in the lamination direction by the discharge operation of the nozzle unit.

[0011] The method for manufacturing a three-dimensional structure according to the present disclosure is a method for manufacturing a desired three-dimensional structure by sequentially stacking a number of layers using a fused deposition modeling method, comprising the steps of: discharging molten resin from a nozzle to form a non-overhang structure without an overhang; and discharging the resin from the nozzle to form an overhang structure having an overhang on the non-overhang structure, wherein in at least the step of forming the overhang structure, the resin discharged from the nozzle is cooled by injecting gas from multiple angles.

[0012] This allows the resin to cool and solidify before its shape deforms under its own weight, making it possible to manufacture a three-dimensional structure with an overhang without providing a support member to support the overhang from below. [Effects of the Invention]

[0013] The present invention provides an additive manufacturing apparatus and a method for manufacturing three-dimensional structures that can produce higher quality three-dimensional structures. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a cross-sectional view showing the configuration of an additive manufacturing apparatus according to Embodiment 1. [Figure 2] Figure 2 is a plan view showing the configuration of the cooling section of the additive manufacturing apparatus according to Embodiment 1. [Figure 3] Figure 3 is a flowchart of the three-dimensional structure manufacturing method according to Embodiment 1. [Figure 4] Figure 4 shows comparative examples and embodiments of three-dimensional structures. [Figure 5] Figure 5 is a cross-sectional view showing the configuration of the additive manufacturing apparatus according to Embodiment 2. [Figure 6] Figure 6 is a plan view showing the configuration of the cooling section of the additive manufacturing apparatus according to Embodiment 2. [Modes for carrying out the invention]

[0015] The following describes specific embodiments of this disclosure in detail with reference to the drawings. However, this disclosure is not limited to the following embodiments. Also, for clarity, the following descriptions and drawings have been simplified as appropriate.

[0016] (Embodiment 1) <Configuration of an additive manufacturing system> First, the configuration of the additive manufacturing apparatus according to this embodiment 1 will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing the configuration of the additive manufacturing apparatus according to embodiment 1. Figure 2 is a plan view showing the configuration of the cooling section of the additive manufacturing apparatus according to embodiment 1. The additive manufacturing apparatus 1 is a so-called 3D printer. The additive manufacturing apparatus 1 forms a desired three-dimensional structure L by sequentially stacking a number of layers on a stage S using fused deposition modeling with thermoplastic resin. As shown in Figure 1, the additive manufacturing apparatus 1 includes a nozzle section 10 and a cooling section 20.

[0017] In the following explanation, the xyz 3D Cartesian coordinate system will be used as appropriate. In this embodiment 1, the z direction is defined as the stacking direction of the three-dimensional structure L. The +z direction is defined as upward, and the -z direction is defined as downward.

[0018] The nozzle unit 10 extrudes molten resin F, for example, from a filament or pellet, toward the stage S. The nozzle unit 10 moves in the xy plane while extruding resin F from the resin discharge port 11, which has a circular opening. When the nozzle unit 10 has extruded a predetermined amount of resin F and formed the first layer L1 on the stage S, it moves in the +z direction. Then, the nozzle unit 10 moves again in the xy plane while extruding resin F from the resin discharge port 11, forming the second layer L2 on top of the first layer L1. Figure 1 shows the state in which the first layer L1 has been formed on the stage S, and the second layer L2, third layer L3, and fourth layer L4 are being stacked on top of it, and the fifth layer L5 is being stacked. In this way, the nozzle unit 10 stacks multiple layers Ln (where n is an integer of 2 or more) to form a three-dimensional structure L. In this embodiment, the nozzle unit 10 moves upward (+z direction) to form the next layer, but the stage S may also move downward (-z direction).

[0019] Resin F is a thermoplastic resin. For example, poly lactic acid (PLA), acrylonitrile butadiene styrene (ABS), polyamide (PA), polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polystyrene (PS), acrylic, polymethyl methacrylate (PMMA), polyphenylene ether (PPE), polyacetal (POM), polycarbonate (PC), polybutylene terephthalate (PBT) resin, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), liquid crystal polymer (LCP), fluororesin, urethane resin, elastomer, etc. can be used.

[0020] The cooling unit 20 is a cylindrical integrally formed member provided so as to surround the nozzle unit 10. The cooling unit 20 according to the present embodiment is provided with a cylindrical cavity for accommodating the nozzle unit 10 inside at the central portion, but it may not be cylindrical, for example, it may be a polygonal shape such as a quadrilateral or a hexagon. Further, the outer surface of the cooling unit 20 is circular as shown in FIG. 2, but it may be a polygonal shape such as a quadrilateral or a hexagon. Furthermore, the upper surface and the lower surface of the cooling unit 20 are planes parallel to each other. The material of the cooling unit is, for example, metal, resin, etc., and is not particularly limited. The cooling unit 20 cools the resin F by injecting the gas AR onto the resin F discharged from the resin discharge port 11. Note that the gas AR is not limited to air, and other gases such as nitrogen may be used. As shown in FIGS. 1 and 2, the cooling unit 20 includes a gas injection port 21 and a gas flow path 22.

[0021] The gas injection port 21 is provided for injecting the gas AR against the resin F discharged from the resin discharge port 11. As shown in FIG. 1, a plurality of gas injection ports 21 are arranged on the lower side (-z direction side) surface of the cooling unit 20 so as to surround the resin discharge port 11 in the vicinity of the resin discharge port 11.

[0022] When the nozzle unit 10 moves in the xy plane direction while discharging the resin F, the cooling unit 20 also moves in the xy plane direction together with the nozzle unit 10. Therefore, if the surface of the cooling unit 20 where the gas injection port 21 is provided is at the same position as the resin discharge port 11 or is located below the resin discharge port 11 (-z direction side), the resin F discharged from the resin discharge port 11 will be dragged onto the surface where the gas injection port 21 is provided. Therefore, in order to suppress this dragging, the surface where the gas injection port 21 is provided is preferably located above the resin discharge port 11 (+z direction side).

[0023] Inside the integrally formed cooling unit 20, a gas flow path 22, which is a cavity through which the gas AR can flow, is provided. The gas flow path 22 is a flow path that guides the gas AR introduced into the cooling unit 20 from a gas supply unit (not shown) through the gas inlet 23 to the gas injection port 21. The gas flow path 22 includes a main flow path 221 and a plurality of branch flow paths 222.

[0024] The main flow path 221 is a flow path concentric with the resin discharge port 11. As shown in FIG. 2, in the present embodiment, the main flow path 221 is in a C-shaped form, but is not limited thereto. For example, it may be in a circular form in which both ends of the main flow path 221 shown in FIG. 2 are continuously connected. In the present embodiment, the inner diameter of the main flow path 221 is the same from one end to the other end, but may be made different in order to control the flow rate of the gas AR injected from the plurality of gas injection ports 21.

[0025] The branch channels 222 connect the main channel 221 and the gas injection port 21. More specifically, the branch channels 222 are channels that branch off from the main channel 221 and extend diagonally downward toward the gas injection port 21. The number of branch channels 222 corresponds to the number of gas injection ports 21. There is no particular limit to the number of gas injection ports 21, but four or more is preferred. Typical branch channels 222 branch off from the inner surface of the main channel 221 at substantially equal intervals and extend toward the axial center of the resin outlet 111. That is, each of the multiple branch channels 222 has substantially the same angle with the branch channels 222 that are radially adjacent to the axial center of the resin outlet 111. This arrangement makes it possible to make the flow rate of gas AR injected from the gas injection port 21 substantially uniform. However, the angles may be changed in order to make the flow rates of gas AR injected from each of the multiple gas injection ports 21 different from each other. Furthermore, the inner diameters of each of the multiple branch channels 222 may be the same or different.

[0026] The gas AR introduced into the cooling section 20 via the gas inlet 23 flows through the main channel 221, spreading almost all around the cooling section 20. The gas AR is then branched into multiple streams by the branch channels 222 and guided diagonally downward toward the gas injection port 21. As a result, the resin F discharged from the resin discharge port 11 is sprayed with gas AR from multiple angles. Therefore, the additive manufacturing apparatus 1 can suppress deformation of the three-dimensional structure L due to insufficient cooling of the resin F, and can manufacture a higher quality three-dimensional structure L.

[0027] Here, it is preferable that the resin F discharged from the resin discharge port 11 is cooled to below the glass transition temperature by the cooling unit 20. Therefore, the additive manufacturing apparatus 1 may set the temperature and flow rate of the gas AR so as to cool the resin F discharged from the resin discharge port 11 to below the glass transition temperature.

[0028] <Method for manufacturing three-dimensional structures> Next, a method for manufacturing a three-dimensional structure using the additive manufacturing apparatus 1 according to this embodiment 1 will be described.

[0029] First, the three-dimensional structure L will be described with reference to Figure 1. The three-dimensional structure L is manufactured by laminating a large number of layers Ln of resin F. In this embodiment, the three-dimensional structure L comprises an overhang structure having an overhang portion T and a non-overhang structure not having an overhang portion T.

[0030] The overhang portion T referred to here is the portion formed by protruding from the non-overhang structure composed of the first layer L1 to the fourth layer L4 in the xy plane direction, as shown in the fifth layer L5 in Figure 1. Note that the non-overhang structure does not necessarily have to be a four-layer structure as described above. Because there is space below (-z direction side) the overhang portion T, if the resin F temperature is higher than the glass transition temperature, there is a risk that the shape may deform due to the weight of the resin F. Therefore, in fused deposition modeling, for example, a support member may be provided to support the overhang portion T from below. When fabrication is performed with a support member, it is necessary to remove the support member from the three-dimensional structure L after fabrication. In this case, burrs may be generated on the three-dimensional structure L, or traces of the support member may remain, which may lead to a decrease in the quality of the three-dimensional structure L. However, in the manufacturing method of the three-dimensional structure L according to this embodiment, the installation of a support member is unnecessary. The manufacturing method of the three-dimensional structure L according to this embodiment will be described below.

[0031] The method for manufacturing the three-dimensional structure L according to Embodiment 1 will be described with reference to Figure 3. Figure 3 is a flowchart of the method for manufacturing the three-dimensional structure according to Embodiment 1. Note that the order of the steps is not limited to this and may be rearranged as appropriate.

[0032] First, the additive manufacturing apparatus 1 extrudes molten resin F from the nozzle section 10 to form a non-overhang structure without an overhang section T (step S101). As shown in Figure 1, the additive manufacturing apparatus 1 stacks the first layer L1 to the fourth layer L4 to form a non-overhang structure.

[0033] Next, the additive manufacturing apparatus 1 extrudes molten resin F from the nozzle section 10 to form an overhang structure having an overhang section T on a non-overhang structure (step S102). In step S102, the resin F extruded from the nozzle section 10 is cooled by spraying gas AR from multiple angles. Therefore, since the resin F solidifies due to cooling before its own weight can deform its shape, there is no need to provide a support member to support the overhang section T from below.

[0034] If the layering process is not terminated (step S103: NO), the additive manufacturing apparatus 1 executes step S101 again. If the layering process is terminated (step S103: YES), the three-dimensional structure L is removed from the stage S.

[0035] Furthermore, the cooling of the resin F by injecting gas AR from the cooling unit 20 may be performed not only in the step of forming the overhang structure (step S102), but also in the step of forming the non-overhang structure (step S101).

[0036] <Examples> The following describes an example of a method for manufacturing a three-dimensional structure using the additive manufacturing apparatus 1 according to Embodiment 1. Figure 4 shows a comparative example and an example of a three-dimensional structure. The upper figure of Figure 4 is a comparative example of a three-dimensional structure fabricated by an additive manufacturing apparatus without a cooling unit 20. The lower figure of Figure 4 is an example of a three-dimensional structure L fabricated by an additive manufacturing apparatus 1 equipped with a cooling unit 20 according to Embodiment 1.

[0037] In both the comparative example and the example, a mixture of polylactic acid and a masterbatch was used as the resin F. Furthermore, the discharge conditions for the resin F from the nozzle 10 were set as follows for both the comparative example and the example: the resin discharge port 11 had a diameter of 3 mm, the width of each layer Ln was 4 mm, and the thickness of each layer Ln was 2 mm. In the example, the pressure of the gas AR supplied to the cooling unit 20 was 0.4 MPa.

[0038] In the comparative example shown in the upper part of Figure 4, the overhang portion T sags due to the weight of the resin F because it is not cooled by the injection of gas AR. On the other hand, in the embodiment shown in the lower part of Figure 4, the overhang portion T solidifies before it sags due to the cooling by the injection of gas AR.

[0039] As described above, the additive manufacturing apparatus 1 in Embodiment 1 cools the resin F discharged from the resin discharge port 11 by injecting gas AR from multiple angles. This suppresses the decrease in tensile strength due to insufficient cooling of the resin F, and enables the manufacture of a higher quality three-dimensional structure L. Furthermore, the additive manufacturing apparatus 1 in Embodiment 1 can manufacture a three-dimensional structure L having an overhang portion T without providing a support member to support the overhang portion T from below. Therefore, there is no risk of a decrease in the quality of the three-dimensional structure L due to the removal of the support member.

[0040] (Embodiment 2) The configuration of the additive manufacturing apparatus according to this second embodiment will be described with reference to Figures 5 and 6. Figure 5 is a cross-sectional view showing the configuration of the additive manufacturing apparatus according to this second embodiment. Figure 6 is a plan view showing the configuration of the cooling section of the additive manufacturing apparatus according to this second embodiment. The additive manufacturing apparatus 1 according to this second embodiment has the same configuration as the additive manufacturing apparatus 1 according to this first embodiment, except for the cooling section 20. Therefore, the configuration of the cooling section 20 according to this second embodiment will be described here.

[0041] <Cooling Unit Configuration> As shown in Figures 5 and 6, the cooling unit 20 includes a gas injection port 21, a gas flow path 22, and a refrigerant flow path 24. Note that the gas injection port 21 and gas flow path 22 have the same configuration as those in Embodiment 1, so their description is omitted.

[0042] The refrigerant flow path 24 is a concentric flow path with the resin outlet 11. Refrigerant flows through the refrigerant flow path 24 to regulate the temperature of the cooling unit 20. Refrigerant introduced into the cooling unit 20 from the refrigerant inlet 24a flows through the refrigerant flow path 24 and flows out of the cooling unit 20 from the refrigerant outlet 24b. Refrigerant continues to flow through the refrigerant flow path 24 while the cooling unit 20 is being cooled.

[0043] After the nozzle 10 dispenses a predetermined amount of resin F, the cooled cooling unit 20 descends, as shown in Figure 5. The three-dimensional structure L, composed of layers L1 to L4 laminated by the dispensing action of the nozzle 10, is then pressed against the cooling unit 20. This cools the three-dimensional structure L by contact with the cooling unit 20, suppressing deformation due to heat accumulation. Furthermore, the compression of the three-dimensional structure L along the lamination direction (z-direction) by being pressed against the cooling unit 20 improves the tensile strength of the three-dimensional structure L.

[0044] Furthermore, in order to allow the cooling unit 20 to move smoothly downward or upward relative to the nozzle unit 10, it is preferable that the outer diameter Φ10 of the nozzle unit 10 is larger than the inner diameter Φ20 of the cooling unit 20, as shown in Figure 5.

[0045] Furthermore, the cooling of the cooling unit 20 with the refrigerant may also be for the purpose of cooling the gas AR injected from the gas injection port 21. This allows the additive manufacturing apparatus 1 to cool the gas AR without, for example, providing an air cooler between a gas supply unit (not shown) and the gas inlet 23.

[0046] As described above, according to the additive manufacturing apparatus 1 of this second embodiment, the three-dimensional structure L can be cooled and compressed by pressing the cooling unit 20, which is cooled by a refrigerant, against the three-dimensional structure L. As a result, the additive manufacturing apparatus 1 can suppress deformation of the three-dimensional structure L due to heat accumulation, and furthermore, improve the tensile strength of the three-dimensional structure L.

[0047] It should be noted that the present invention is not limited to the embodiments described above, and can be modified as appropriate without departing from the spirit of the invention. [Explanation of symbols]

[0048] 1. Additive manufacturing device 10 Nozzle section 11 Resin discharge port 20 Cooling section 21 Gas nozzles 22 Gas flow path 23 Gas Inlet 24 Refrigerant flow path 24a Refrigerant inlet 24b Refrigerant outlet 221 Main channel 222 Tributary channel AR gas F Resin L Three-dimensional structure Ln, L1-L5 layer S Stage T Overhang section Outer diameter of nozzle section Φ10 Φ20 Inner diameter of the cooling section

Claims

1. A nozzle section having a resin discharge port for dispensing molten resin, A build-up apparatus comprising a cylindrical cooling section provided so as to surround the nozzle section, The cooling unit comprises a gas injection port for injecting gas into the resin discharged from the resin discharge port, and a gas flow path for guiding the gas to the gas injection port. Multiple gas injection ports are arranged near the resin discharge port, surrounding the resin discharge port. The gas flow path comprises a main flow path concentric with the resin discharge port, and branch flow paths that branch the gas flowing through the main flow path into multiple branches and guide the gas diagonally downward toward the gas injection port. Additive manufacturing equipment.

2. When the resin is discharged, the resin discharge port is located above the resin with respect to the position of the gas injection port. The additive manufacturing apparatus according to claim 1.

3. The cooling unit injects the gas into the resin so as to cool the resin discharged from the resin discharge port to a temperature below the glass transition temperature. The additive manufacturing apparatus according to claim 1 or 2.

4. The cooling unit further comprises a refrigerant channel through which a refrigerant for temperature control of the cooling unit flows. After the resin is discharged, the cooling unit is pressed against the laminated resin along the lamination direction by the discharge operation of the nozzle unit. The additive manufacturing apparatus according to claim 1 or 2.

5. A method for manufacturing a three-dimensional structure, which involves sequentially stacking multiple layers using fused deposition modeling to produce a desired three-dimensional structure, A process of discharging molten resin from a nozzle to form a non-overhang structure without an overhang, The process includes the step of discharging the resin from the nozzle portion to form an overhang structure having an overhang portion on the non-overhang structure, In at least the step of forming the overhang structure, the resin discharged from the nozzle is cooled by spraying gas from multiple angles. Three-dimensional structure manufacturing method.

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