Hot end for three-dimensional laminate molding

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 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 layered 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 feeder 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 attach the heater: (1) inserting it into a hole in the nozzle, or (2) mounting it as an exterior heater block between the guide and nozzle. The following explanation will be given for the above (1), but the present invention can be applied to either of the above (1) or (2).

[0004] The filament feed device feeds the filament into the guide hole with a predetermined feed 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 discharged 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 a high thermal conductivity.

[0006] Generally, ABS resin (acrylonitrile butadiene styrene copolymer) or PLA (poly(lactic acid)) is used for the filament. The applicant also proposes PVC as a material for the filament in Patent Document 2. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2016-107456 A [Patent Document 2] JP 2020-104374 A Summary of the Invention [Problem to be solved by the invention]

[0008] Among the above 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 a part of the filament becomes stagnant in the nozzle hole. The stagnant filament may then burn to the nozzle hole, causing nozzle clogging.

[0009] In addition, the boundary between the unmelted and molten parts of the filament is inside the nozzle hole, but if the amount of heat applied to the filament by the heater increases due to factors such as a high nozzle temperature or a slow modeling speed, this boundary may move upward and reach the guide. Since the nozzle and guide are screwed together, there is a gap at the connection, and part of the molten filament that reaches the guide remains in this gap. Most of the guide is not easily affected by heating by the heater and is therefore at a low temperature, but the connection with the nozzle becomes hot, so the filament that remains in the gap will burn. The burning that occurs in the gap may spread into the nozzle hole and cause the nozzle to become clogged.

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

[0011] To prevent the filament from 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 cylinder portion made of resin and having the nozzle hole; a metallic nozzle outer cylinder portion surrounding the outer periphery of the nozzle inner cylinder portion and to which the heater is attached; has.

[0014] The nozzle inner cylinder is desirably made of PTFE (polytetrafluoroethylene).

[0015] The nozzle hole desirably has a surface roughness Ra of 0.8 μm or less.

[0016] A height L0 of a filament melting portion where the filament is heated and melted in the nozzle hole is desirably set lower than a height L2 of the nozzle inner cylindrical portion.

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

[0018] The diameter D of the nozzle hole of the nozzle inner cylinder 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 bushing and the nozzle cap may be formed as a single piece.

[0020] Moreover, the three-dimensional additive manufacturing apparatus of the present invention includes the above-mentioned three-dimensional additive manufacturing hot end. Effect of the Invention

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

[0022] In addition, in the hot end for three-dimensional 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 the molten filament to the nozzle hole and reduces buckling of the filament, making it possible to carry out modeling for a long period of time. [Brief description 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. [Diagram 2] FIG. 2 is a side view of a hot end according to one embodiment of the present invention. [Diagram 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 components of the hot end. [Diagram 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 PREFERRED EMBODIMENTS

[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 laminated 71, 72 on a print bed 11 to produce a three-dimensional structure 70.

[0027] Examples of the filament 80 include PVC (polyvinyl chloride), ABS resin, and PLA (polylactic acid). PVC is versatile and has excellent stability, and is less expensive than ABS resin and PLA, which is effective in reducing manufacturing costs. To obtain desired characteristics, the filament 80 may also contain additives such as so-called fillers, stabilizers, plasticizers, and colorants. Examples of additives include lead-based stabilizers and tin-based stabilizers.

[0028] The filament 80 is pulled out by a feed roller 13 from a filament supply device (not shown) through a guide tube 12, and is supplied to a hot end 20 that 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 form of the three-dimensional additive manufacturing device 10 is not limited to this.

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

[0030] Then, the filament 80 is supplied while the hot end 20 is moved in a plane parallel to the print bed 11. As a result, a molten filament 81 is discharged from the nozzle 22 at the tip, and a 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 to sequentially form a second layer 72, a third layer, ..., and the three-dimensional structure 70 is produced.

[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 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 of two members 30, 40 and 50, 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 its 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 in the nozzle hole 61, causing the molten filament 81 to be discharged from the reduced diameter portion at the tip.

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

[0036] <Guide 21: Guide outer cylinder portion 30> The outer guide cylinder portion 30 is cylindrical and has a filament introduction hole 32 at its upper end, a nozzle cap insertion hole 33 below that, 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 since it is in direct contact with the nozzle outer cylinder 50 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 the center through which the filament 80 is inserted. The diameter D of the guide hole 41 can be set according to the diameter d of the filament 80 (see FIG. 5). In order 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 means the clearance between the guide hole 41 and the filament 80, and by setting the upper and lower limits as described above, the filament 80 is guided in a straight line without waving in the guide hole 41, and buckling can be suppressed.

[0040] The nozzle cap 40 has at its tip a fitting recess 42 into which a nozzle inner cylinder portion 60, which will be described later, fits.

[0041] It is desirable that the nozzle cap 40 be made of a material with a small coefficient of friction in order to guide the filament 80 to the nozzle 22 with low friction. On the other hand, when the temperature of the nozzle cap 40 rises, the filament 80 melts in the guide hole 41, leading to softening of the filament 80. For this reason, it is desirable that the nozzle cap 40 be made of a material with a high heat insulating effect. An example of this type of material is PTFE (polytetrafluoroethylene). PTFE is a material with an extremely small 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 suitable as a 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 cylinder portion 50 and a nozzle inner cylinder portion 60.

[0044] The nozzle outer cylinder 50 has a shape in which a cylindrical body 51 having a conically tapered tip and a cylindrical shaft 52 protrudes from the upper end of the body 51. The shape of the body 51 can be a hexagonal column or other shape that makes it easy to screw the guide 21 and the nozzle 22 together.

[0045] The nozzle outer cylinder part 50 has a nozzle inner cylinder insertion hole 53 opened in the center, which penetrates the body part 51 and the shaft part 52. The nozzle inner cylinder insertion hole 53 has a positioning hole 54 whose diameter is reduced with a step near the tip, and the nozzle inner cylinder part 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 provided. Wires 15 and 16 (see FIG. 1) are connected to the heater 56 and the temperature sensor.

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

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

[0049] The nozzle outer cylinder 50 is made of a material having heat resistance and good thermal conductivity because it is heated by the heater 56. For example, aluminum alloy or brass can be mentioned.

[0050] <Nozzle 22: Nozzle inner cylinder 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 therein 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 tapered 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 an outer surface with a reduced diameter, and has 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 desired that the filament 80 be introduced into the unmelted filament portion 64 without resistance and smoothly guided in a straight line to the molten filament portion 65. In addition, in the molten filament portion 65, it is necessary to discharge the molten filament 81 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 constituting the nozzle hole 61 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 a step, and the filament 80 can be inserted smoothly.

[0056] Moreover, in order for the nozzle hole 61 to introduce the filament 80 without resistance in the filament unmelted portion 64 and to suppress adhesion and retention of the molten filament 81 in the filament molten portion 65, it is desirable that the inner surface of the nozzle hole 61, i.e., the nozzle inner cylinder portion 60, be made of a low-friction material. On the other hand, the nozzle inner cylinder portion 60 is heated by the heater 56 of the nozzle outer cylinder portion 50 to melt the filament 80 in the nozzle hole 61, so heat resistance is required.

[0057] Therefore, it is required to use a resin material having a low coefficient of friction and heat resistance for the nozzle inner cylinder 60. One example of such a material is PTFE. PTFE has an extremely small 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] In order to promote low friction of the nozzle hole 61, it is desirable to smooth the surface of 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. By adjusting the surface roughness Ra of the nozzle hole 61, the filament 80 can be introduced without resistance in the filament unmelted part 64, and adhesion and retention of the molten filament 81 can be suppressed in the filament melted part 65. It is possible to manufacture a metallic nozzle having a nozzle hole with a surface roughness Ra of 0.8 μm or less by drilling a nozzle hole and polishing or coating the nozzle hole. However, even if such a metallic nozzle is used as the nozzle inner cylinder part 60, adhesion and retention of the molten filament 81 are more likely to occur than in a nozzle made of resin such as PTFE, so it is difficult to make the nozzle inner cylinder part 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 at 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 fits inside 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 amount of heat applied to the filament by the heater 56 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 reduced diameter 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 portion 50 is fixed to the guide outer cylinder portion 30. The nozzle inner cylinder portion 60 is positioned by fitting its tip reduced diameter portion 63 into the positioning hole 54 of the nozzle outer cylinder portion 50. The nozzle cap 40 has its upper end positioned by the positioning step portion 34 of the guide outer cylinder portion 30. The upper end of the nozzle inner cylinder portion 60 has a fitting protrusion 62 that fits into the fitting recess 42 of the nozzle cap 40, so that 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 gap is created at the seam 66 between the guide hole 41 and the nozzle hole 61. For this reason, it is desirable that the guide outer cylinder 30 and the nozzle outer cylinder 50 have dimensions such that, when the mounting screw 55 is tightened, a gap S is created 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 screw 55, the guide outer cylinder 30 and the nozzle outer cylinder 50 can push the nozzle cap 40 and the nozzle inner cylinder 60 together to tightly fit 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 three-dimensional additive manufacturing apparatus 10 via a holder 14. By operating the heater 56, the hot end 20 heats the nozzle outer cylinder 50, which in turn heats the nozzle inner cylinder 60.

[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 is formed at the joint 66 between the guide hole 41 and the nozzle hole 61. Therefore, the filament 80 that has passed 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 than the joint 66 (L0 < L2), the molten filament 81 does not reach the joint 66.

[0069] The inner nozzle cylinder portion 60 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 that has entered the nozzle hole 61 travels without substantially receiving frictional resistance at the unfused portion 64 of the filament. Also, at 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.

[0070] Then, the molten filament 81 in the filament melting portion 65 can be discharged downward from the tip of the nozzle hole 61 while suppressing a decrease in the flow velocity by the extrusion force of the unfused filament 80 sequentially fed into the nozzle hole 61. Therefore, the extrusion force for discharging the molten filament 81 can also be small, and it is possible to prevent the unfused filament 80 from buckling due to the reaction force.

[0071] The molten filament 80 extruded from the tip of the nozzle hole 61 is sequentially formed into a first layer 71, a second layer 72, a third layer ... of the three-dimensional structure 70 on the print bed 11, as shown in FIG. 1, thereby producing the three-dimensional structure 70. EXAMPLES

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

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

[0074] PVC is a material that is prone to sticking and burning when melted, making it unsuitable for three-dimensional additive manufacturing, but when the hot end 20 of the present invention was used, it was possible to perform modeling for a long period of time of more than 10 hours. This is because the use of the hot end 20 of the present invention reduced the adhesion of the molten filament to the nozzle hole, reduced buckling of the filament, and also suppressed burning of the filament 80.

[0075] For comparison, a hot end was used in which the nozzle outer cylinder and the nozzle inner cylinder were made from a single metal part, and molding was performed in the same manner. However, the nozzle hole was opened by drilling and was not polished.

[0076] As a result, with the comparative metal hot end, 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 interpreted 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 cylinder portion 60 are configured as separate members, but they may be integrated into a single seamless part.

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

[0080] 10. 3D additive manufacturing equipment 20 Hot End 21 Guide 22 Nozzle 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 cylinder portion made of resin in which the nozzle hole is formed; a metallic nozzle outer cylinder portion surrounding the outer periphery of the nozzle inner cylinder portion and to which the heater is attached; It has a tip of the nozzle inner cylinder portion protruding from the nozzle outer cylinder portion, and the nozzle hole opening at the tip of the nozzle inner cylinder portion; Hot end for 3D additive manufacturing.

2. The nozzle hole does not expand in diameter, and the diameter of the nozzle hole is reduced toward the tip side. 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 having the guide hole and made of PTFE (polytetrafluoroethylene); a guide outer cylinder portion surrounding an outer periphery of the nozzle cap and 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. A diameter D of the nozzle hole of the nozzle inner cylinder portion and the guide hole of the nozzle cap, and a 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 piece. The hot end for three-dimensional additive manufacturing according to claim 5 or 6.

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

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