3D Additive Manufacturing Hot End

Abstract

To provide a hot end for three-dimensional laminate molding that can reduce nozzle clogging even when a material that easily burns, such as PVC, is used as a filament.SOLUTION: A hot end 20 for three-dimensional laminate molding according to the present invention includes: a guide 21 having a guide hole 41 through which a filament 80 is fed; and a nozzle 22 having a nozzle hole 61 communicating with the guide hole and a heater 56 attached thereto. The nozzle includes: a nozzle inner cylinder part 60 made of resin and having the nozzle hole; and a metallic nozzle outer cylinder 50 that surrounds an outer periphery of the nozzle inner cylinder part and to which the heater is attached. A tip of the nozzle inner cylinder part protrudes from the nozzle outer cylinder, and the nozzle hole opens at the tip of the nozzle inner cylinder.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a technology that enables the use of filaments made of materials such as PVC (polyvinyl chloride), which is considered unsuitable as a filament material because it tends to burn, when creating three-dimensional structures using a three-dimensional additive manufacturing device, also known as a three-dimensional printer, and relates to the hot end that extrudes the filament within that technology. [Background technology]

[0002] Fused Deposition Modeling (FDM) is a well-known additive manufacturing method for 3D printers. In FDM 3D additive manufacturing devices, a molten thermoplastic resin filament is sequentially deposited on a print bed from a hot end that can move in a plane to create a three-dimensional structure.

[0003] A hot end generally comprises a guide, a nozzle, and a heater. The guide has a guide hole that guides the filament, and the filament fed from the filament feeding device passes through the guide hole and enters the nozzle. The nozzle has a nozzle hole that communicates with the guide hole. There are two ways to install the heater: (1) inserting it into a hole in the nozzle, or (2) mounting it as an external heater block between the guide and nozzle. The following explanation focuses on the above (1), but the present invention is applicable to both (1) and (2).

[0004] The filament feeding device feeds the filament into the guide hole with a predetermined feeding force. The filament fed into the guide hole reaches the nozzle hole, where it is heated by a heater and melted. The molten filament is then extruded downward from the tip of the nozzle hole by the pushing force of the unmelted filament that is successively fed into the nozzle hole.

[0005] For example, in Patent Document 1, the nozzle is made of an aluminum alloy that has an excellent heat transfer coefficient.

[0006] ABS resin (acrylonitrile butadiene styrene copolymer) or PLA (poly(lactic acid)) is generally used for the filament. In addition, the applicant has proposed PVC as a material for the filament in Patent Document 2. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-107456 [Patent Document 2] Japanese Patent Application Publication No. 2020-104374 Summary of the Invention [Problem to be solved by the invention]

[0008] Among the above-mentioned filament materials, PVC in particular is prone to adhering to metal surfaces when melted. When the heated and melted filament adheres to the inner surface of the nozzle hole, frictional resistance increases, the flow rate of the filament decreases, and part of the filament becomes stagnant in the nozzle hole. The stagnant filament may then burn to the nozzle hole, causing nozzle clogging.

[0009] Furthermore, the boundary between the unmelted and molten portions of the filament is located within the nozzle hole, but if the heater heats the filament too much due to factors such as a high nozzle temperature or a slow build speed, this boundary can move upward and reach the guide. Because the nozzle and guide are connected by a screw, a gap exists at the connection, and some of the molten filament that reaches the guide becomes trapped in this gap. While most of the guide is not easily affected by heating from the heater and remains cold, the connection with the nozzle becomes hot, causing the filament trapped in the gap to scorch. Scorching that occurs in the gap can spread into the nozzle hole and cause nozzle clogging.

[0010] Furthermore, while the filament passes through the guide hole, as described above, the unmelted filament is subjected to the feeding force and the reaction force against the extrusion force for discharging the molten filament. If the compressive load caused by these forces exceeds the allowable buckling load of the filament, the filament will deform into a wavy shape and buckle.

[0011] To prevent filament buckling, it is necessary to keep the filament straight, but the diameter D of the guide hole is generally about 4 mm, which is larger than the diameter d (1.75 mm) of a typical filament. In other words, the clearance between the filament and the guide hole is large at 1.125 mm, making it difficult to keep the filament straight.

[0012] The object of the present invention is to provide a hot end for three-dimensional additive manufacturing that can reduce nozzle clogging even when a material that easily burns, such as PVC, is used as a filament. [Means for solving the problem]

[0013] The hot end for three-dimensional additive manufacturing of the present invention comprises: a guide having a guide hole through which the filament is fed; a nozzle having a nozzle hole communicating with the guide hole; A hot end for three-dimensional additive manufacturing, comprising a heater attached to the nozzle, The nozzle is a nozzle inner cylindrical portion made of resin and having the nozzle hole; a metallic nozzle outer cylinder portion that surrounds the outer periphery of the nozzle inner cylinder portion and to which the heater is attached; It has.

[0014] The nozzle inner cylindrical portion is preferably made of PTFE (polytetrafluoroethylene).

[0015] The nozzle holes preferably have a surface roughness Ra of 0.8 μm or less.

[0016] It is desirable that a height L0 of a molten filament portion where the filament is heated and melted in the nozzle hole be lower than a height L2 of the nozzle inner cylindrical portion.

[0017] The guide is a nozzle cap made of PTFE (polytetrafluoroethylene) having the guide hole; a guide outer cylinder portion that surrounds the outer periphery of the nozzle cap and is engaged with the nozzle outer cylinder portion; The configuration may have the following.

[0018] The diameter D of the nozzle hole of the nozzle inner cylindrical portion and the guide hole of the nozzle cap, and the diameter d of the filament are 0.225mm≧(Dd) / 2≧0.075mm It is desirable to do so.

[0019] The nozzle barrel and the nozzle cap may be formed as a single piece.

[0020] Furthermore, a three-dimensional additive manufacturing apparatus according to the present invention includes the above-described three-dimensional additive manufacturing hot end. [Effects of the Invention]

[0021] According to the hot end for three-dimensional additive manufacturing of the present invention, the nozzle is formed from a nozzle inner cylinder made of resin and a nozzle outer cylinder made of metal. By making the nozzle inner cylinder made of resin, adhesion of the molten filament to the nozzle hole can be reduced. Meanwhile, the nozzle outer cylinder, to which the heater is attached, is made of metal with good thermal conductivity, so heat conduction can be maintained favorably and the filament can be melted.

[0022] Furthermore, in the hot end for 3D additive manufacturing of the present invention, by setting the diameter D of the nozzle hole and the guide hole relative to the diameter d of the filament as described above, the clearance between them can be reduced, and the filament can be kept straight, thereby reducing buckling of the filament.

[0023] The three-dimensional additive manufacturing device of the present invention uses the above-mentioned three-dimensional additive manufacturing hot end, which reduces adhesion of molten filament to the nozzle hole and reduces buckling of the filament, making it possible to manufacture for long periods of time. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic diagram of a fused deposition modeling three-dimensional additive manufacturing apparatus according to one embodiment of the present invention. [Figure 2] FIG. 2 is a side view of a hot end according to one embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is an exploded cross-sectional view of the hot end components. [Figure 5] FIG. 5 is a cross-sectional view of the hot end in an operational state with the filament being fed and melted. DETAILED DESCRIPTION OF THE INVENTION

[0025] The hot end 20 of the present invention will now be described with reference to the drawings.

[0026] <3D additive manufacturing device 10> 1 shows one embodiment of an FDM-type three-dimensional additive manufacturing apparatus 10. The three-dimensional additive manufacturing apparatus 10 supplies a filament 80 to a hot end 20, and heats and melts the filament 81, which is then sequentially stacked on a print bed 11 in layers 71 and 72, thereby producing a three-dimensional structure 70.

[0027] Examples of the filament 80 include PVC (vinyl chloride), ABS resin, and PLA (polylactic acid). PVC is highly versatile, has excellent stability, and is cheaper than ABS resin and PLA, which is effective in reducing manufacturing costs. To obtain desired properties, additives such as fillers, stabilizers, plasticizers, and colorants can also be blended into the filament 80. Examples of additives include lead-based stabilizers and tin-based stabilizers.

[0028] The filament 80 is drawn from a filament supply device (not shown) through a guide tube 12 by a feed roller 13, and supplied to a hot end 20, which serves as an extrusion means. The hot end 20 is connected to a moving means (not shown) for the hot end 20 via a holder 14, and is movable in the horizontal direction. Note that the configuration of the 3D additive manufacturing device 10 is not limited to this.

[0029] The hot end 20 is equipped with a heater 56 (see FIG. 3) as heating means and a thermocouple as a temperature sensor (not shown), and wiring 15 and 16 for these are arranged as shown in FIG.

[0030] Then, the hot end 20 is moved in a plane parallel to the print bed 11 while supplying the filament 80. As a result, the molten filament 81 is ejected from the nozzle 22 at the tip, and the first layer 71 of the three-dimensional structure 70 is formed on the print bed 11. After the first layer 71 is formed, the print bed 11 is lowered and the second layer 72, third layer, and so on are formed in sequence to produce the three-dimensional structure 70.

[0031] <Overall configuration of Hot End 20> Fig. 2 is a side view of a hot end 20 according to an embodiment of the present invention, and Fig. 3 is a cross-sectional view. The hot end 20 is configured by attaching a nozzle 22 to the tip of a guide 21 as shown in Fig. 2.

[0032] Fig. 3 is a cross-sectional view taken along the axis of the hot end 20 in Fig. 2, and Fig. 4 is an exploded cross-sectional view. In the illustrated embodiment, the guide 21 and the nozzle 22 constituting the hot end 20 are made from two members 30 and 40 and 50 and 60, respectively.

[0033] The guide 21 includes a guide outer cylinder 30 to which the holder 14 (see FIG. 1) can be attached, and a nozzle cap 40 that fits onto the guide outer cylinder 30. The nozzle cap 40 is formed with a guide hole 41 through which the filament 80 passes.

[0034] The nozzle 22 also includes a nozzle outer cylinder 50 having a heater 56 and a temperature sensor (not shown) attached to the lower end thereof, and a nozzle inner cylinder 60 that fits into the nozzle outer cylinder 50. A nozzle hole 61 having a reduced diameter at the tip is formed in the nozzle inner cylinder 60. When the nozzle outer cylinder 50 is heated by the heater 56, the nozzle inner cylinder 60 is heated and melts the filament 80 within the nozzle hole 61, causing the molten filament 81 to be discharged from the reduced diameter portion at the tip.

[0035] The detailed structure and materials of each member will be described below.

[0036] <Guide 21: Guide outer cylinder portion 30> The guide outer cylinder portion 30 is cylindrical and has a filament introduction hole 32 at its upper end, a nozzle cap insertion hole 33 below it, and a nozzle attachment hole 35 at its lower end, which is the tip.

[0037] More specifically, a positioning step 34 protrudes inward at the boundary between the filament introduction hole 32 and the nozzle cap insertion hole 33. The nozzle attachment hole 35 is a hole with a larger diameter than the nozzle cap insertion hole 33, and has a nozzle attachment screw 36 cut into its inner surface, through which the nozzle 22 is attached.

[0038] The guide outer cylinder 30 is required to be heat resistant because it is in direct contact with the nozzle outer cylinder 50, which is heated by the heater 56. For this reason, it can be made from a heat resistant resin such as polyimide, or a metal with low thermal conductivity such as stainless steel.

[0039] <Guide 21: Nozzle cap 40> The nozzle cap 40 is a cylindrical member that is attached to the nozzle cap insertion hole 33 of the guide outer cylinder 30. The nozzle cap 40 has a guide hole 41 in its center, through which the filament 80 is inserted. The diameter D of the guide hole 41 can be set based on the diameter d of the filament 80 (see FIG. 5 ). To suppress buckling of the filament 80 and guide it in a straight line, the guide hole 41 is preferably set to satisfy 0.225 mm ≧ (Dd) / 2 ≧ 0.075 mm, preferably 0.175 mm ≧ (Dd) / 2 ≧ 0.125 mm. (Dd) / 2 represents the clearance between the guide hole 41 and the filament 80. By setting the upper and lower limits as described above, the filament 80 is guided in a straight line within the guide hole 41 without undulation, thereby suppressing buckling.

[0040] The nozzle cap 40 has a fitting recess 42 formed at its tip into which a nozzle inner cylindrical portion 60 (described later) fits.

[0041] The nozzle cap 40 is preferably made of a material with a low coefficient of friction so that it can guide the filament 80 to the nozzle 22 with low friction. However, if the temperature of the nozzle cap 40 rises, the filament 80 will melt inside the guide hole 41, causing the filament 80 to soften. For this reason, the nozzle cap 40 is preferably made of a material with a high thermal insulation effect. An example of this type of material is PTFE (polytetrafluoroethylene). PTFE is a material with an extremely low dynamic friction coefficient of 0.03 to 0.08 (measurement method: JIS K 6935) and a low heat transfer coefficient of 0.23 W / m K (measurement method: JIS A 1412), making it an ideal material for the nozzle cap 40.

[0042] As shown in FIG. 4, the nozzle cap 40 is configured to be inserted into the guide outer cylinder portion 30 from below, and the upper surface of the nozzle cap 40 abuts against the positioning step portion 34 to form the guide 21.

[0043] <Nozzle 22: nozzle outer cylinder portion 50> The nozzle 22 attached to the tip of the guide 21 has a double structure consisting of a nozzle outer cylindrical portion 50 and a nozzle inner cylindrical portion 60.

[0044] The nozzle outer cylinder 50 has a cylindrical body 51 whose tip is tapered into a conical shape, and a cylindrical shaft 52 protruding from the upper end of the body 51. The shape of the body 51 can be a hexagonal pillar or other shape that facilitates screw connection between the guide 21 and the nozzle 22.

[0045] The nozzle outer cylinder 50 has a nozzle inner cylinder insertion hole 53 formed in the center, which penetrates the body 51 and the shaft 52. The nozzle inner cylinder insertion hole 53 has a positioning hole 54 whose diameter is reduced by a step near the tip, and the nozzle inner cylinder 60 can be positioned by the step between the nozzle inner cylinder insertion hole 53 and the positioning hole 54.

[0046] A heater insertion hole is provided in the body 51 outside the nozzle inner cylinder insertion hole 53, and the heater 56 is inserted into the hole and a temperature sensor (not shown, for example, a thermocouple) is also disposed in the hole. Wiring 15, 16 (see FIG. 1) are connected to the heater 56 and the temperature sensor.

[0047] Although it is sufficient to install one heater 56, it is preferable to install two heaters 56, that is, to provide heater insertion holes in two locations on either side of the nozzle hole 61, and insert and install a heater 56 into each of them, so that the filament inside the nozzle hole 61 is heated uniformly.

[0048] The shaft portion 52 has a mounting screw 55 cut on the outer periphery thereof, which can be screwed onto the nozzle mounting screw 36 of the guide outer cylinder portion 30 .

[0049] The nozzle outer cylinder 50 is made of a material that is heat resistant and has good thermal conductivity, since it is heated by the heater 56. Examples of the material include aluminum alloy and brass.

[0050] <Nozzle 22: Nozzle inner cylindrical portion 60> The nozzle inner cylinder 60 attached to the nozzle outer cylinder 50 can be in a cylindrical shape as shown in Figures 3 and 4. The nozzle inner cylinder 60 has a nozzle hole 61 formed in the center, through which the filament 80 is inserted and through which the filament 80 is melted and discharged.

[0051] The nozzle hole 61 is a hole that communicates with the guide hole 41 of the nozzle cap 40 and receives the supply of the filament 80, and has a reduced diameter at its tip. The diameter of the nozzle hole 61 will be described later.

[0052] The nozzle inner cylinder 60 has an upper end formed with a fitting protrusion 62 that fits into the fitting recess 42 of the nozzle cap 40. The lower end of the nozzle inner cylinder 60 has a tapered outer surface and a tip reduced diameter portion 63 that fits into the positioning hole 54 of the nozzle outer cylinder 50.

[0053] Within the nozzle hole 61, there are an unmelted filament portion 64, which is a region where the unmelted filament 80 enters, and a molten filament portion 65, which is a region where the molten filament 81 accumulates. The unmelted filament portion 64 is an upper region of the nozzle hole 61, and the molten filament portion 65 is a lower region of the nozzle hole 61.

[0054] It is desirable that the filament 80 be introduced into the unmelted filament portion 64 without resistance and be smoothly guided in a straight line to the melted filament portion 65. In addition, in the melted filament portion 65, the molten filament 81 needs to be discharged from the tip of the nozzle hole 61 without adhering to or remaining on the inner surface of the guide hole 41. Therefore, the nozzle hole 61 and the nozzle inner cylinder portion 60 that constitutes it are specified as follows.

[0055] First, it is desirable to set the diameter of the nozzle hole 61 to a diameter D that is approximately the same as that of the guide hole 41. By making the diameters of the nozzle hole 61 and the guide hole 41 approximately the same, the nozzle hole 61 and the guide hole 41 can be connected without any steps, allowing the filament 80 to be inserted smoothly.

[0056] Furthermore, the nozzle hole 61 is desirably configured with an inner surface of the nozzle hole 61, i.e., the nozzle inner cylinder 60, made of a low-friction material in order to introduce the filament 80 without resistance into the filament unmelted portion 64 and to prevent adhesion or retention of the molten filament 81 in the filament melted portion 65. On the other hand, the nozzle inner cylinder 60 is heated by the heater 56 of the nozzle outer cylinder 50 to melt the filament 80 in the nozzle hole 61, and therefore is required to have heat resistance.

[0057] Therefore, it is necessary to use a resin material that has a low coefficient of friction and heat resistance for the nozzle inner cylinder 60. PTFE is an example of such a material. PTFE has an extremely low coefficient of dynamic friction of 0.03 to 0.08 and an extremely high melting point of 327°C, making it suitable as a material for the nozzle inner cylinder 60.

[0058] To promote low friction in the nozzle hole 61, it is desirable to smooth the inner surface of the guide hole 41 by polishing or the like so that the surface roughness Ra is 0.8 μm or less. Adjusting the surface roughness Ra of the nozzle hole 61 allows the filament 80 to be introduced without resistance into the unmelted filament portion 64 and also prevents the molten filament 81 from adhering to or remaining in the molten filament portion 65. Note that it is possible to manufacture a metal nozzle having a nozzle hole with a surface roughness Ra of 0.8 μm or less by drilling a nozzle hole and then polishing or coating the nozzle hole. However, even if such a metal nozzle is used as the nozzle inner cylinder 60, the molten filament 81 is more likely to adhering to or remaining in the metal than in a nozzle made of a resin such as PTFE, making it difficult to form the nozzle inner cylinder 60 out of metal.

[0059] Inside the nozzle hole 61, as described above, the filament 80 melts at the filament melting part 65. The guide hole 41 and the nozzle hole 61 are connected with almost no step as they have substantially the same diameter D, but actually, there is a step at the joint 66, although it is very small. If this step exists in the filament melting part 65, the molten filament 81 may stay at the joint 66, causing decomposition and charring. Therefore, the filament melting part 65 is set so that the filament melting part 65 can be accommodated within the nozzle hole 61. Specifically, as shown in FIG. 5, with respect to the length L0 from the tip of the nozzle inner cylinder part 60 to the upper end of the filament melting part 65, the length L2 of the nozzle hole 61 is set to satisfy L0 < L2.

[0060] Note that the height of the filament melting part 65 varies depending on the shaping conditions. When the heating amount of the heater 56 to the filament increases due to a high nozzle temperature or a slow shaping speed, etc., the filament melting part 65 may reach a position higher than the nozzle outer cylinder part 50. Therefore, when the height of the nozzle outer cylinder part 50 is L1 as shown in FIG. 5, it is necessary to set it so that L2 > L1. For example, when the heater temperature is 220 °C, the nozzle discharge diameter is 0.5 mm, and the average filament feeding speed is 20 - 40 mm / min, if L2 ≥ L1 + 5 mm, then L0 < L2 can be satisfied.

[0061] <Assembly of the hot end 20> Prepare the guide outer cylinder part 30, the nozzle cap 40, the nozzle outer cylinder part 50, and the nozzle inner cylinder part 60, and assemble the hot end 20.

[0062] Specifically, as shown in FIG. 4, first, insert the nozzle cap 40 through the nozzle mounting hole 35 of the guide outer cylinder part 30 and insert it into the nozzle cap insertion hole 33 to form the guide 21. Also, for the nozzle 22, insert the nozzle inner cylinder part 60 through the nozzle inner cylinder insertion hole 53 of the nozzle outer cylinder part 50 and fit the tip diameter-reduced part 63 into the positioning hole 54. Then, screw the mounting screw 55 of the nozzle outer cylinder part 50 onto the mounting screw 36 of the guide 21.

[0063] 3, the nozzle outer cylinder 50 is fixed to the guide outer cylinder 30. The nozzle inner cylinder 60 is positioned by fitting the reduced diameter tip portion 63 into the positioning hole 54 of the nozzle outer cylinder 50. The nozzle cap 40 has its upper end positioned by the positioning step 34 of the guide outer cylinder 30. The fitting protrusion 62 at the upper end of the nozzle inner cylinder 60 fits into the fitting recess 42 of the nozzle cap 40, and the guide hole 41 and the nozzle hole 61 communicate with each other.

[0064] The nozzle cap 40 and the nozzle inner cylinder 60 need to be tightly fitted together so that no gaps form at the seam 66 between the guide hole 41 and the nozzle hole 61. For this reason, the guide outer cylinder 30 and the nozzle outer cylinder 50 are desirably sized so that, when the mounting screws 55 are tightened, gaps S form between the upper end of the shaft 52 and the upper end of the nozzle mounting hole 35, and between the lower end of the guide outer cylinder 30 and the body 51 of the nozzle outer cylinder 50, as shown in FIG. 3. As a result, by tightening the mounting screws 55, the guide outer cylinder 30 and the nozzle outer cylinder 50 can press the nozzle cap 40 and the nozzle inner cylinder 60 together, tightly fitting the seam 66.

[0065] <Operation of the 3D additive manufacturing device 10> 1, the hot end 20 described above is connected to wires 15 and 16 and attached to the 3D additive manufacturing apparatus 10 via a holder 14. When the heater 56 of the hot end 20 is activated, the nozzle outer cylinder 50 is heated, and thereby the nozzle inner cylinder 60 is also heated.

[0066] In this state, the feed roller 13 is rotated to supply the filament 80 to the hot end 20.

[0067] The filament 80 fed into the hot end 20 reaches the nozzle hole 61 through the guide hole 41. By setting the diameter D of the guide hole 41 such that 0.225 mm ≥ (D - d) / 2 ≥ 0.075 mm with respect to the diameter d of the filament 80, the clearance between the filament 80 and the guide hole 41 can be reduced, and the filament 80 can be kept straight without being deformed into a wave shape. Therefore, even if the feeding force of the filament 80 and the reaction force from the unfused portion 64 of the filament act on the filament 80 in the guide hole 41, it is possible to prevent the filament 80 from buckling.

[0068] Both the guide hole 41 and the nozzle hole 61 have substantially the same diameter D. Therefore, almost no step occurs at the joint 66 between the guide hole 41 and the nozzle hole 61. Therefore, the filament 80 passing through the guide hole 41 is smoothly guided into the nozzle hole 61. As described above, since the filament melting portion 65 is located at a position lower (L0 < L2) than the joint 66, the molten filament 81 does not reach the joint 66.

[0069] The inner cylinder portion 60 of the nozzle is made of PTFE with a low coefficient of friction. Also, the surface roughness Ra of the nozzle hole 61 is adjusted to be 0.8 μm or less. Therefore, the filament 80 entering the nozzle hole 61 travels without substantially receiving frictional resistance in the unfused portion 64 of the filament. Also, in the filament melting portion 65, it is melted by the heating from the heater 56, and the molten filament 81 does not adhere to or stay on the inner surface of the nozzle hole 61. <​​​​​The molten filament 80 ejected from the tip of the nozzle hole 61 sequentially forms the first layer 71, second layer 72, third layer, etc. of the three-dimensional structure 70 on the print bed 11, as shown in Figure 1, thereby producing the three-dimensional structure 70. [Example]

[0072] A three-dimensional structure 70 was fabricated using a PVC filament 80 (diameter 1.75 mm) and a three-dimensional additive manufacturing device 10 equipped with a hot end 20 of the present invention.

[0073] The hot end 20 had a guide 21 with a guide outer cylinder 30 made of polyimide and a nozzle cap 40 made of PTFE. The nozzle 22 had a nozzle outer cylinder 50 made of aluminum alloy and a nozzle inner cylinder 60 made of PTFE. The diameters D of the guide hole 41 and the nozzle hole 61 were 2 mm, and the tip discharge diameter of the nozzle hole 61 was 0.5 mm. The surface roughness Ra of the nozzle hole 61 was finished to 0.8 or less. The nozzle outer cylinder 50 was heated to 220°C by a heater 56. The average feed speed of the filament 80 was 20 to 40 mm / min.

[0074] PVC is a material that tends to stick and burn when melted, making it unsuitable for 3D additive manufacturing, but when the hot end 20 of the present invention was used, it was possible to carry out modeling for a long period of time, more than 10 hours. This is because the use of the hot end 20 of the present invention reduced adhesion of the molten filament to the nozzle hole, reduced buckling of the filament, and prevented the filament 80 from burning.

[0075] For comparison, a hot end was used in which the nozzle outer and inner cylinders were made from a single metal part, but the nozzle holes were drilled and not polished.

[0076] As a result, with the metal hot end used in the comparative example, the molten PVC burned to the nozzle hole, and the model could only be created in less than an hour.

[0077] The above description of the embodiment is for the purpose of explaining the present invention, and should not be construed as limiting the invention described in the claims or narrowing its scope. Furthermore, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications are possible within the technical scope described in the claims.

[0078] For example, in the above embodiment, the nozzle cap 40 and the nozzle inner cylindrical portion 60 are configured as separate members, but they may be integrated into a single seamless component.

[0079] 5, it is desirable that the length L3 of the nozzle cap 40 and the nozzle inner cylinder 60 be long enough to reach the filament introduction hole 32 of the guide outer cylinder 30. By making L3 long, it is possible to suppress the wobbling of the filament 80 and to stably hold the filament 80 straight in the guide hole 41 at an early stage. [Explanation of symbols]

[0080] 10. Three-dimensional additive manufacturing equipment 20 Hotend 21 Guide 22 nozzles 30 Guide outer cylinder 40 Nozzle Cap 41 Guide hole 50 nozzle outer cylinder 60 Nozzle inner cylinder 61 Nozzle hole

Claims

1. a guide having a guide hole through which the filament is fed; a nozzle having a nozzle hole communicating with the guide hole; A hot end for three-dimensional additive manufacturing, comprising a heater attached to the nozzle, The nozzle is a nozzle inner cylindrical portion made of resin in which the nozzle hole is opened; a metallic nozzle outer cylinder portion that surrounds the outer periphery of the nozzle inner cylinder portion and to which the heater is attached; It has a tip of the nozzle inner cylindrical portion protruding from the nozzle outer cylindrical portion, and the nozzle hole opening at the tip of the nozzle inner cylindrical portion; Hot end for 3D additive manufacturing.

2. The nozzle hole does not expand in diameter but contracts in diameter toward the tip end. The hot end for three-dimensional additive manufacturing according to claim 1.

3. The nozzle inner cylinder is made of PTFE (polytetrafluoroethylene). The hot end for three-dimensional additive manufacturing according to claim 1 or 2.

4. The nozzle hole has a surface roughness Ra of 0.8 μm or less. The hot end for three-dimensional additive manufacturing according to any one of claims 1 to 3.

5. The guide is a nozzle cap made of PTFE (polytetrafluoroethylene) having the guide hole; a guide outer cylinder portion that surrounds the outer periphery of the nozzle cap and is engaged with the nozzle outer cylinder portion; having The hot end for three-dimensional additive manufacturing according to any one of claims 1 to 4.

6. The diameter D of the nozzle hole of the nozzle inner cylindrical portion and the guide hole of the nozzle cap, and the diameter d of the filament are 0.225mm≧(D-d) / 2≧0.075mm That is, The hot end for three-dimensional additive manufacturing according to claim 5.

7. a height L0 of a filament melting portion where the filament is heated and melted in the nozzle hole is lower than a height L2 of the nozzle inner cylindrical portion; The hot end for three-dimensional additive manufacturing according to any one of claims 1 to 6.

8. The nozzle inner cylinder and the nozzle cap are formed as a single component. The hot end for three-dimensional additive manufacturing according to claim 5 or 6.

9. A three-dimensional additive manufacturing device comprising the three-dimensional additive manufacturing hot end according to any one of claims 1 to 8.

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