strands

Abstract

The present invention provides a resin strand having excellent bendability, which enables smooth modeling of a 3D printer. The aforementioned strand is used as a modeling material for a 3D printer, is formed in a linear shape, is made of resin, and has a helical groove portion formed on an outer peripheral surface in an axial direction.

Description

TECHNICAL FIELD

[0001] The present application relates to a strand. BACKGROUND

[0002] As a device that forms an object having a three-dimensional shape, a 3D (three-dimensional) printer that adopts a thermal fusion layering method in which a resin that is plasticized by heat is accumulated layer by layer is known. The 3D printer can mold an object of a three-dimensional shape without a mold, a jig, or the like. Furthermore, it is also possible to mold an object of a three-dimensional shape that is difficult to form in injection molding technology.

[0003] As shown in Figure 12 As a 3D printer, there is a case in which a linear resin strand (filament) 203 wound around a bobbin 201 is continuously fed to a nozzle 207 through a tube 205, the strand 203 is made plasticized by heat of a heater, and is discharged from the nozzle 207 to be layered on a base 209 (for example, refer to Patent Literature 1).

[0004] Patent Literature 1: Japanese Patent Application Laid-Open No. 2019-123241

[0005] However, in the above-described 3D printer, in the case where a curved portion K is present in a supply path of the strand 203 fed from the bobbin 201 to the nozzle 207, there is a possibility that the strand 203 is broken or damaged by a bending force applied to the strand 203 at the curved portion K. SUMMARY

[0006] Therefore, an object of the present application is to provide a resin strand excellent in bendability that enables smooth molding of a 3D printer.

[0007] The present application is constituted by the following features.

[0008] A strand that is used as a molding material for a 3D printer, is formed in a linear shape, and is made of resin, characterized in that a helical groove portion is formed on an outer peripheral surface in an axial direction.

[0009] EFFECT OF THE INVENTION

[0010] According to the present application, it is possible to provide a resin strand excellent in bendability that enables smooth molding of a 3D printer. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1A is a perspective view of the strand of the present embodiment.

[0012] Figure 1B is a cross-sectional view of the strand of the present embodiment perpendicular to the length direction.

[0013] Figure 2is an overall configuration view of a manufacturing apparatus for manufacturing the strand of the present embodiment.

[0014] Figure 3 is a front view of a mold provided at a strand extraction portion of a resin bath portion constituting the manufacturing apparatus.

[0015] Figure 4 is a perspective view of a strand of another configuration.

[0016] Figure 5 is a perspective view of a strand of another configuration.

[0017] Figure 6 is a perspective view of a strand of another configuration.

[0018] Figure 7 is a perspective view of a strand of another configuration.

[0019] Figure 8 is a perspective view of a strand of another configuration.

[0020] Figure 9 is a perspective view of a strand of another configuration.

[0021] Figure 10 is an enlarged view of a part of the outer peripheral surface of the strand.

[0022] Figure 11 is a perspective view of a strand of another configuration.

[0023] Figure 12 is a schematic configuration view of a 3D printer using a resin strand. DETAILED DESCRIPTION

[0024] Hereinafter, the embodiment of the present application will be explained in detail with reference to the drawings.

[0025] (Strand)

[0026] Figure 1A is a perspective view of a strand of the present embodiment, Figure 1B is a sectional view of the strand of the present embodiment perpendicular to the length direction.

[0027] As Figure 1A and Figure 1BAs shown, the strand 1 of the present embodiment is a linear resin material used as a modeling material for a 3D printer. The strand 1 has a base material 3 in which a thermoplastic resin is a main component, and a plurality of fiber bundles 5 impregnated in the base material 3 and extending continuously in the axial direction. The fiber bundles 5 are bundled by a plurality of fibers 7 and are arranged in the center of the strand 1 in a twisted state with each other. In this example, there are three fiber bundles 5, and the three fiber bundles 5 are twisted with each other. Further, the outer periphery of the base material 3 or the outer peripheral surface of the strand 1 is formed in a substantially circular shape in a cross section perpendicular to the length direction (axial direction) of the strand 1, except for a portion of a groove 9 described later.

[0028] The strand 1 has a plurality of (three in this example) grooves 9 in the outer peripheral surface thereof. The grooves 9 are formed helically in the axial direction. Preferably, each groove 9 is formed at equal intervals in the circumferential direction in a cross section perpendicular to the axial direction, and the direction of the helix and the pitch P of the helix are the same. The pitch P of the helix of the groove 9 is preferably 0.001 mm to 500 mm. It is particularly preferable to be 0.005 mm to 100 mm. Further, the width dimension Wa of the groove 9 is preferably 0.001 mm to 10 mm, and particularly preferably 0.005 mm to 5 mm. The depth dimension H of the groove 9 is preferably 0.001 mm to 10 mm, and particularly preferably 0.005 mm to 1 mm.

[0029] The diameter d of the strand 1 is about 0.1 mm to 10 mm, and the ratio (P / d) of the diameter d to the pitch P is preferably 0.0001 to 5000, more preferably 0.001 to 500, and particularly preferably 0.01 to 50. Further, the ratio (P / Wa) of the pitch P to the width dimension Wa of the groove 9 is preferably 0.0001 to 500000, more preferably 0.01 to 50000, and particularly preferably 0.1 to 5000. By being in the above range, the flexibility of the strand 1 described later can be improved.

[0030] The 3D printer using the strand 1 adopts a so-called fused deposition modeling method, and the fused deposition modeling method forms a three-dimensional shaped molded article by gradually accumulating the strand 1 in which the thermoplastic resin component is fused by heat. In the fused deposition modeling method, regarding each layer, the previously formed layer and the next layer are bonded in a semi-solid (softened) state while being molded. The 3D printer is not particularly limited as long as it can form a molded article by gradually accumulating a resin in a plasticized state due to heat. For example, as the 3D printer, a 3D printer provided with a support plate that can freely move in the up-down, left-right, and front-back directions, and a supply portion that supplies the thermoplastic resin component of the strand 1 while plasticizing it to the support plate is exemplified.

[0031] As the fiber bundle 5 constituting the strand 1, organic fibers such as polyethylene fibers, aramid fibers, XYRON fibers, inorganic fibers such as boron fibers, glass fibers, carbon fibers, metal fibers, and rock fibers can be used. As the reinforcing fiber, a fiber subjected to surface treatment can be used in order to improve the adhesion strength of the resin and the fiber.

[0032] As the thermoplastic resin that is the main component of the base material 3, polypropylene, polyolefin-based resins such as polyethylene, acrylonitrile-butadiene-styrene resins, polystyrene resins, polyethylene terephthalate, polybutylene terephthalate, polyester-based resins such as polylactic acid, polyamide-based resins, aramid-based resins, polyetherimide, polyarylimide, polyarylate, polyether ether ketone, polyallyl ether ketone, polybenzimidazole, polyether sulfone, polysulfone, polyvinylidene fluoride resins, liquid crystal polymers, polycarbonate-based resins, polyformaldehyde, or polyphenylene sulfide, and the like can be used.

[0033] As for them, a single resin can be used, or a thermoplastic resin in which a plurality of resins are mixed can be used in order to improve the heat resistance, heat distortion temperature, heat aging, tensile properties, bending properties, creep properties, compression properties, fatigue properties, impact properties, and sliding properties of the thermoplastic resin portion. As an example, PEEK / PTFE, PEEK / PBI, and the like can be used. In addition, a resin to which short fibers such as carbon fibers and glass fibers, talc, and the like are added can be used.

[0034] By adding an antioxidant such as a phenol-based, thioether-based, or phosphite-based antioxidant, an ultraviolet absorber such as a benzotriazole-based or triazine-based ultraviolet absorber, a metal deactivator such as a hydrazide-based or amide-based metal deactivator, and the like to the thermoplastic resin, the durability of the molded article can be improved.

[0035] By adding a plasticizer such as a phthalic acid-based or polyester-based plasticizer, the softness of the thermoplastic resin can be improved, and the molding accuracy during molding and the softness of the molded article can be improved.

[0036] By adding a flame retardant such as a halogen-based, phosphate-based, inorganic-based, or intumescent-based flame retardant to the thermoplastic resin, the flame retardancy of the molded article can be improved.

[0037] By adding a nucleating agent such as a phosphate metal salt-based or sorbitol-based nucleating agent to the thermoplastic resin, the thermal expansion during molding can be controlled, and the molding accuracy can be improved.

[0038] By adding a permanent antistatic agent such as a nonionic-based, anionic-based, or cationic-based permanent antistatic agent to the thermoplastic resin, the antistatic properties of the molded article can be improved.

[0039] By adding a lubricant such as a hydrocarbon-based or metal soap-based lubricant to the thermoplastic resin, the lubricity of the continuous fiber-reinforced strand can be improved, and thus the feeding of the strand during molding can be facilitated.

[0040] In addition, in a 3D printer in which a molded article is molded using a linear resin-made strand, the strand is fed from a bobbin to a nozzle when the molded article is molded. At this time, if a curved portion exists on a strand feeding path, a bending force is applied to the strand at the curved portion, and there is a possibility that the strand is broken or damaged.

[0041] In addition, in recent years, in order to improve the mechanical strength of a molded article, a molding method of a fiber-reinforced resin (FRP: Fiber Reinforced Plastics) using a 3D printer of a fused deposition modeling (FDM) method in which a continuous fiber-reinforced strand is used has been proposed and is being widely used. However, when a molded article is molded using the existing continuous fiber-reinforced strand, at a portion where the curvature is large (the radius of curvature is small), there is a case where the bending property of the continuous fiber-reinforced strand is low and fiber peeling occurs, which is peeling of the fiber inside. As a result, there is a case where a difference occurs between a passage in design and a passage at the time of actual molding, and as a result, the molding accuracy of the molded article decreases, and in addition, a gap occurs in the molded article and the quality decreases. These decreases in molding accuracy and quality have a tendency to occur significantly when a strand having a large diameter is used.

[0042] In contrast to this, according to the strand 1 of the present embodiment, the spiral groove portion 9 is formed in the outer peripheral surface in the axial direction, so the surface area of the outer peripheral surface can be increased, and the bending property can be improved. Thus, when the strand 1 is fed from the bobbin to the nozzle in the 3D printer, even if a bending force is applied at a curved portion due to the curved portion existing on the feeding path, the strand can be fed along the curved feeding path without being broken or damaged. Therefore, the molding of the 3D printer can be smoothly performed. In addition, the strand can be easily wound around the bobbin without being broken or damaged.

[0043] Further, a plurality of spiral groove portions 9 are formed, so the bending property can be further improved. In addition, the plurality of groove portions 9 are formed at equal intervals in the circumferential direction in a cross section perpendicular to the axial direction of the strand 1, and the spirals of these groove portions 9 are in the same direction and have the same pitch, so the bending property can be improved well in balance with respect to all directions. Further, the breakage or damage of the strand at the curved portion can be avoided without considering the position of the groove portion 9 of the strand 1 and the bending direction of the curved portion of the feeding path.

[0044] Further, the strand 1 can greatly increase the strength by the fiber bundle 5 bundled by the fiber 7, but becomes difficult to bend due to the inclusion of the fiber bundle 5. However, the spiral groove 9 formed on the outer peripheral surface can ensure good bendability. Further, by providing such a spiral groove 9, as a side effect, when modeling the modeled article by a 3D printer of a thermal fusion lamination type, it is also possible to model while the strand 1 is well bent, it is possible to suppress the decrease in the modeling accuracy of the modeled article, the decrease in quality due to the gap in the modeled article, and it is possible to model a high-quality modeled article.

[0045] Further, the plurality of fiber bundles 5 bundled by the fiber 7 are twisted, so it is also possible to improve the bendability of the fiber bundle 5 itself, and it is possible to suppress the decrease in bendability due to the inclusion of the fiber bundle.

[0046] (MANUFACTURING APPARATUS)

[0047] Next, an example of a manufacturing apparatus for manufacturing the strand 1 of the present embodiment will be described.

[0048] Figure 2 is a whole structure view of the manufacturing apparatus 100 for manufacturing the strand 1 of the present embodiment.

[0049] As shown in Figure 2 , the manufacturing apparatus 100 is provided with a fiber material supply section 11, a resin bath section 13, a cooling section 15, and a twisting section 17. In the manufacturing apparatus 100, the fiber bundle 5 discharged from the fiber material supply section 11 is dipped in the thermoplastic resin R as the base material 3 by the resin bath section 13 and then extracted as the strand 1. Further, the strand 1 extracted from the resin bath section 13 is cooled by the cooling section 15 while being rotated around the axis center by the twisting section 17, and is wound around the twisting section 17.

[0050] The fiber material supply section 11 is provided with a plurality of (three in the present example) spools 21 and a plurality of guide rollers 23. The fiber bundles 5 are wound around the respective spools 21, and the fiber bundles 5 are fed out from the spools 21. The respective fiber bundles 5 fed out from the spools 21 are arranged at intervals from each other by the guide rollers 23, and are guided to the resin bath section 13.

[0051] The resin bath section 13 is provided with a cylindrical resin bath tank 25 extending upward and downward, and the thermoplastic resin R in a molten state is stored in the resin bath tank 25. The resin bath tank 25 is provided with a compounding extruder (not shown) that melts the raw material of the thermoplastic resin R to be added and extrudes it into the resin bath tank 25, and the molten thermoplastic resin R is supplied from the compounding extruder. The resin bath tank 25 has a fiber bundle guide inlet 27 at the upper portion thereof, and the fiber bundle 5 is fed into the fiber bundle guide inlet 27. Further, the resin bath tank 25 has a strand extraction section 29 at the side portion of the lower end thereof, and the strand 1 in which the fiber bundle 5 is dipped in the base material 3 is extracted to the side from the strand extraction section 29.

[0052] In the resin bath tank 25 of the resin bath section 13, an impregnation roller 41 and a guide roller 45 are provided inside. The impregnation roller 41 and the guide roller 45 are rotatably supported about a horizontal axis. Multiple impregnation rollers 41 are provided along the vertical direction inside the resin bath tank 25, and the guide roller 45 is provided at the lower end inside the resin bath tank 25.

[0053] Three fiber bundles 5, fed from the fiber bundle inlet 27 of the resin bath 25, are alternately hung on and in contact with the impregnation roller 41. Thus, each fiber bundle 5 travels meanderingly within the resin bath 25. Furthermore, the impregnation roller 41 is not necessarily capable of rotation. Additionally, the lower end of each fiber bundle 5 within the resin bath 25 is hung on the inlet roller 45, and its path changes from vertical to horizontal, guiding it towards the strand extraction section 29.

[0054] A mold 55 is provided at the strand extraction section 29 where the strand 1 is extracted, and the fiber bundle 5 of the aforementioned strand 1 is impregnated in the substrate 3. The mold 55 has a circular opening 57 that narrows in the extraction direction of the strand 1. Figure 3 As shown, the inner diameter of the opening 57 on the extraction direction side is formed to correspond to the outer diameter of the manufactured strand 1. Furthermore, the mold 55 has multiple (three in this example) inwardly projecting grooves forming protrusions 59 on the inner circumferential surface of the opening 57. These groove-forming protrusions 59 are preferably formed at equal intervals in the circumferential direction on a cross-section perpendicular to the extraction direction of the strand 1.

[0055] Figure 3 The diagram illustrates an example where groove-forming protrusions 59 of the die 55 are formed at equal intervals in the circumferential direction on a cross section perpendicular to the extraction direction of the strand 1. However, the groove-forming protrusions 59 do not necessarily need to be formed at equal intervals. When the groove-forming protrusions 59 are not formed at equal intervals, the pitch of the grooves 9 is not evenly spaced, but the bending flexibility of the strand 1 can be improved compared to the case where the grooves 9 are not formed.

[0056] Alternatively, as described later, a mold without the groove forming the protrusion 59 can also be used.

[0057] The cooling section 15 has a cooling groove 31 that is longer along the extraction direction of the strand 1 extracted from the strand extraction section 29 of the resin bath section 13. Cooling water W is stored inside the cooling groove 31 as a cooling medium. The strand 1 is pulled into the cooling groove 31 from the resin bath section 13 side. The strand 1 pulled into the cooling groove 31 cools and hardens the thermoplastic resin R, which is the substrate 3, due to the cooling water W stored in the cooling groove 31. The strand 1, which is cooled and hardened by the cooling water W, is extracted from the twisted section 17 side of the cooling groove 31.

[0058] The twisting section 17 has pull-in rollers 35, winding drums 37, and a housing 39. The pull-in rollers 35 are provided on the cooling section 15 side of the housing 39 and are arranged in two pairs of two pairs in a manner facing each other. These pull-in rollers 35 pull the strands 1 into the housing 39 from the cooling section 15. The winding drums 37 rotate about an axis orthogonal to the extending direction of the strands 1. Thus, the winding drums 37 wind the strands 1 pulled into the housing 39 by the pull-in rollers 35. The housing 39 rotates about an axis along the extending direction of the strands 1. Thus, the strands 1 wound on the winding drums 37 of the twisting section 17 by being pulled out from the resin bath section 13 and passing through the cooling section 15 are rotated about the axis, and twisting is performed. In addition, as a mechanism for performing twisting on the strands 1, various mechanisms can be employed, and, for example, a twisting mechanism in which the strands 1 are pulled by a pair of rollers rotating in different directions from each other and are sent to the downstream side, thereby performing twisting on the strands 1 can be used.

[0059] (Method of manufacturing)

[0060] Next, an example of a manufacturing method of the strands 1 by the manufacturing apparatus 100 will be described.

[0061] In the manufacturing apparatus 100, the strands 1 are manufactured by performing an impregnation process, a twisting process, a cooling process, and a winding process.

[0062] (1) Impregnation process

[0063] The impregnation process is a process in which the thermoplastic resin R is impregnated in the fiber bundles 5 by the resin bath section 13 of the manufacturing apparatus 100. In the impregnation process, the fiber bundles 5 discharged from the fiber material supply section 11 and introduced from the fiber bundle guide 27 of the resin bath section 13 pass through the resin bath section 13, and thus the thermoplastic resin R in a molten state stored in the inside of the resin bath 25 is impregnated in the fiber bundles 5.

[0064] Each of the fiber bundles 5 is alternately hung on the plurality of impregnation rollers 41 and travels while contacting the outer circumferential surfaces of these impregnation rollers 41, and thus the plurality of fibers 7 constituting each of the fiber bundles 5 are separated. Thus, with respect to the fiber bundles 5, the thermoplastic resin R is sufficiently impregnated between the fibers 7.

[0065] (2) Twisting process

[0066] The twisting process is a process in which the fiber bundles 5 impregnated with the thermoplastic resin R are twisted. The fiber bundles 5 are wound on the introduction rollers 45 in a state in which they are spaced apart from each other, the travel track is changed to the horizontal direction, and are guided to the strand extraction section 29. At this time, the strands 1 extracted to the downstream side of the resin bath section 13 are rotated about the axis by the twisting section 17. Thus, the fiber bundles 5 are twisted with each other from the state in which they are spaced apart from each other from the introduction rollers 45 toward the strand extraction section 29.

[0067] The fiber bundle 5 to be stranded is gathered at the center portion of the opening portion 57 of the mold 55, whereby the outer periphery of the fiber bundle 5 after stranding is in a state where it is covered with the thermoplastic resin R uniformly in the circumferential direction. Therefore, the strand 1 is drawn out from the opening portion 57 of the mold 55, the outer periphery of the fiber bundle 5 after stranding of the aforementioned strand 1 is covered with the base material 3 composed of the thermoplastic resin R uniformly, and the fibers 7 constituting the fiber bundle 5 do not protrude from the outer periphery (see FIG. 6). Figure 3

[0068] Further, at the time of drawing out the strand 1 from the opening portion 57 of the mold 55, the protrusion 59 is formed in the groove portion 9 on the outer peripheral surface of the strand 1 by the groove portion of the opening portion 57 of the mold 55. At this time, the strand 1 is rotated around the axis by the twisting portion 17, whereby the groove portion 9 of the outer peripheral surface is formed in a spiral shape, respectively. In addition, as described later, a mold without the protrusion 59 of the groove portion can also be used, in which case the groove portion 9 is formed on the base material 3 by the operation of twisting the strand 1 itself.

[0069] (3) Cooling step

[0070] The cooling step is a step of cooling the strand 1 by the cooling portion 15. In the cooling step, the strand 1 drawn out from the strand drawing-out portion 29 of the resin bath portion 13 is drawn into the cooling groove 31 of the cooling portion 15, and then drawn out. Thereby, the strand 1 is cooled and hardened by the thermoplastic resin R as the base material 3 due to the cooling water W stored in the cooling groove 31.

[0071] (4) Winding step

[0072] The winding step is a step of winding the strand 1 around the twisting portion 17. In the winding step, the strand 1 cooled by the cooling portion 15 is drawn into the shell 39 by the drawing-in roller 35 of the twisting portion 17, and wound around the winding bobbin 37 in the shell 39.

[0073] Thus, in the manufacturing device 100, by the above-described steps, the strand 1 in which the groove portion 9 in a spiral shape is formed on the outer peripheral surface and which is excellent in flexibility can be easily manufactured.

[0074] In addition, the configuration of the strand 1 is not limited to the above-described embodiment. For example, in the above-described embodiment, the strand 1 having three fiber bundles 5 is exemplified, but the number of the fiber bundles 5 is not limited to three. Further, it can also be that the strand 1 in which the cross section is circular is manufactured, and then the groove portion 9 in a spiral shape is formed on the outer peripheral surface of the strand 1 by cutting or the like.

[0075] Hereinafter, strands of other configurations will be described.

[0076] Figures 4 to 8 FIGS. 10 to 12 are perspective views of strands of other configurations, respectively.

[0077] Figure 4 ​The strand 1A shown has a fiber bundle 5 formed by binding together multiple fibers 7. This fiber bundle 5 is located at the center of the substrate 3 and extends axially while rotating along the groove 9. Furthermore, in a cross-section perpendicular to the axial direction, similar to the strand 1, except for the portion in the groove 9, the outer periphery of the substrate 3 and the outer peripheral surface of the strand 1A are formed to be approximately circular. That is, the fiber bundle 5 is located in a region within a circle that is concentric with respect to the outer peripheral surface of the strand 1A.

[0078] Figure 5 The line 1B shown will Figure 4 The circumferential width of the groove 9 in the strand 1A shown is reduced, thereby increasing the number of grooves 9. By narrowing the circumferential pitch of the groove 9, the flexibility of the strand 1B can be improved, and the bending resistance can be made uniform regardless of the direction of bending.

[0079] Figure 6 The line 1C shown will Figure 5 The fiber bundle 5 of the strand 1B shown is configured as three (or more) fiber bundles 5. The multiple fiber bundles 5 are respectively arranged at positions symmetrical about the center of the strand 1B. In this case, the uniformity of the bending properties and bending resistance of the strand 1C is also improved. In this case, due to the relatively hard substrate 3, even in the following description... Figure 7 Even when it is difficult to form a groove by twisting the 1D strand, a groove 9 can be reliably formed.

[0080] Figure 7 The strand 1D shown is a strand made from three (or more) fiber bundles 5. In this case, the strand 1D is manufactured using a mold without groove-forming protrusions 59. Therefore, in the case of strand 1D, grooves 9 are formed by twisting the strand 1D itself and even the three (or more) fiber bundles 5 themselves. Thus, in the case of strand 1D, the grooves 9 formed on the outer peripheral surface are not U-shaped, but rather V-shaped. These grooves 9 are also formed in a spiral shape, with their inner surfaces smoothly connected to the outer peripheral surface of the strand 1D. In this case, the grooves 9 are formed by twisting the fiber bundles 5 themselves, so there is no need for additional processing of the grooves 9, simplifying the manufacturing process.

[0081] As another example of forming grooves by twisting the strands themselves or even the fiber bundles themselves, using a mold without groove-forming protrusions 59, the following is shown Figure 8 Stock line 1E, Figure 9 The stock line 1F.

[0082] exist Figure 8 In the case of the strand 1E shown, a single fiber bundle 5 is contained within it. The strand 1E forms a groove 9 by twisting itself and the single fiber bundle 5 contained within it. In this case, the fiber bundle 5 is located at the center of the substrate 3 and extends axially while rotating along the groove 9.

[0083] Further, Figure 9 In the case of the strand 1F shown, a plurality of fiber bundles 5 are enclosed, and as the constituent strand, the same as the strand 1E shown is used. Figure 8 However, compared to the strand 1E, the strand 1F is twisted to a greater degree (the pitch of the spiral is narrower). Therefore, compared to the strand 1E, the depth of the groove portion 9 of the strand 1F is deeper. Due to this, the strand 1F is more difficult to bend than the strand 1E. Figure 7 The cross section of the strand 1D shown is a deformed shape in which three circles are combined, and the cross section of the strand 1F is formed into a shape closer to a circle.

[0084] Figure 10 In order to make the strand 1F shown more difficult to bend than the strand 1E, the strand 1F is twisted to a greater degree than the strand 1E. Figure 8 , Figure 9 A schematic cross-sectional view of the shape of the cross section of the strand 1E, 1F shown, perpendicular to the axial direction, is shown partially enlarged. In addition, Figure 10 The groove portion 9 is schematically shown, and the depth dimension H of the groove portion 9, the width dimension Wa of the groove portion 9, and the circumferential interval L of the groove portions 9 from each other are examples.

[0085] Figure 10 The outer peripheral surface of the strand shown (the outer peripheral surface 3a of the base material 3) is, except for the region between the circumferential end portions 9a, 9b of the same groove portion 9, formed into a substantially circular shape in the same way as the strand 1. The substantially circular shape referred to here means a circular shape or a shape close to a circle, and specifically refers to a shape in which the outer peripheral edge of the cross section of the strand 1, except for the region of the groove portion 9, is formed by a circular arc of the same circle, respectively. In addition, the circular arcs can not necessarily be circular arcs of the same circle, and each circular arc can be disposed so as to include a position at a certain radius from the center of the strand 1. Alternatively, the circle circumscribed by each circular arc can be concentric with the center of the strand 1. Regarding the shape of the outer peripheral surface of the strand other than the groove portion 9 described above, regarding the strand 1E shown, Figure 1A , Figure 1B , Figures 4 to 6 The same applies to the strands 1, 1A, 1B, 1C shown.

[0086] Figure 11 The strand 1G shown can also be constituted not by the fiber bundle 5 but by the base material 3 constituted by a thermoplastic resin alone. In this case, the outer periphery of the base material 3, and even the outer peripheral surface of the strand 1G, is formed into a substantially circular shape in the cross section perpendicular to the axial direction, as described above, except for the portion of the groove portion 9.

[0087] The spiral groove portion 9 of each of the strands 1A, 1B, 1C, 1D, 1E, 1F, 1G described above is formed in the outer peripheral surface along the axial direction, so the surface area of the outer peripheral surface can be increased, and the bendability can be improved. In addition, in order to also ensure sufficient strength of the molded article with respect to each strand, the proportion of the fiber with respect to the entire strand, that is, the fiber volume content ratio is preferably 5% or more and 85% or less.

[0088] Thus, the present application is not limited to the above-described embodiments, and the embodiments can be combined with each other, changed, and applied by those skilled in the art based on the description and known technology, and are intended to be included in the scope of the claims.

[0089] As described above, the following matters are disclosed in the present specification.

[0090] (1) A strand that is used as a modeling material for a 3D printer, is formed in a linear shape, and is made of resin, characterized in that a spiral groove portion is formed on an outer peripheral surface in an axial direction.

[0091] According to the strand, the spiral groove portion is formed on the outer peripheral surface in the axial direction, so the surface area of the outer peripheral surface can be increased, and the bendability can be improved.

[0092] Thus, when the strand is fed from a roll to a nozzle in the 3D printer, even if a bending force is applied at a bending site due to the presence of the bending site in the feeding path, the strand can be fed along the curved feeding path without breakage or damage. Therefore, the modeling of the 3D printer can be smoothly performed. In addition, the strand can be easily wound around the roll without breakage or damage.

[0093] (2) The strand according to (1), characterized in that a plurality of the aforementioned groove portions that are formed in a spiral shape in the same direction and with the same pitch are formed at equal intervals in a circumferential direction in a cross section perpendicular to the axial direction.

[0094] According to the strand, the plurality of spiral groove portions are formed, so the bendability can be further improved. In addition, the plurality of groove portions are formed at equal intervals in the circumferential direction in a cross section, and the spirals of these groove portions are in the same direction and have the same pitch, so the bendability can be improved in balance with respect to all directions.

[0095] (3) The strand according to (1) or (2), characterized in that a plurality of fibers or fiber bundles are included in the aforementioned axial direction.

[0096] According to the strand, the strength can be greatly improved by the fibers or fiber bundles. In addition, although it becomes difficult to bend due to the inclusion of the fibers or fiber bundles, good bendability can be ensured by the spiral groove portions formed on the outer peripheral surface. Thus, even when a modeled object is modeled by a 3D printer of a heat-fusion layering type, the strand can be bent well while the modeling is performed, the decrease in the modeling accuracy of the modeled object or the decrease in quality due to the generation of a gap in the modeled object can be suppressed, and a high-quality modeled object can be modeled.

[0097] (4) The strand according to (3), characterized in that the aforementioned fibers or fiber bundles are twisted.

[0098] According to this strand, the fibers or fiber bundles are twisted, so it is also possible to improve the bendability of the fibers or fiber bundles themselves, and it is possible to suppress a decrease in bendability due to the fibers or fiber bundles.

[0099] (5) The strand according to any one of (1) to (4), characterized in that the portions of the outer periphery in the cross section of the strand perpendicular to the axial direction, except for the regions of the groove portions, are each formed by an arc of a same circle.

[0100] According to this strand, the outer periphery of the cross section is formed by an arc of a same circle, and the outer peripheral surface is formed in a substantially circular shape as a whole, so it is possible to make the supply amount of the strand constant and stabilize the quality of the molded article when the molded article is molded, for example, with a 3D printer.

[0101] This application is based on Japanese Patent Application (Japanese Patent Application No. 2020-185914) filed on November 6, 2020, and Japanese Patent Application (Japanese Patent Application No. 2021-148158) filed on September 10, 2021, and the contents thereof are incorporated herein by reference.

[0102] Explanation of Reference Signs

[0103] 1, 1A, 1B, 1C strand

[0104] 5 fiber bundle

[0105] 7 fiber

[0106] 9 groove portion

Claims

1. A strand for use as a modeling material for a 3D printer, formed in a thread shape, characterized by, a base material containing a thermoplastic resin, a single fiber bundle provided at the center of the base material and bundled with a plurality of fibers and extending continuously in an axial direction, the fibers of the fiber bundle are twisted, and the thermoplastic resin is impregnated between the fibers, a periphery of the fiber bundle is covered with the thermoplastic resin in a circumferential direction, a spiral groove portion is formed in an axial direction on an outer circumferential surface of the base material.

2. The strand according to claim 1, wherein a plurality of the spiral groove portions formed in the same direction and with the same pitch are formed equidistantly in a circumferential direction in a cross section perpendicular to the axial direction.

3. The strand according to claim 1 or 2, wherein a part of an outer periphery in a cross section of the strand perpendicular to the axial direction other than a region of the groove portion is formed by an arc of a same circle, respectively.

4. A strand used as a modeling material for a 3D printer and formed in a linear shape, comprising: a base material containing a thermoplastic resin, a plurality of fiber bundles provided at the center of the base material and bundled with a plurality of fibers and extending continuously in an axial direction, the plurality of fiber bundles are such that the fibers of each fiber bundle are twisted, and the thermoplastic resin is impregnated between the fibers to be twisted with each other, and a periphery of the twisted fiber bundle is covered with the thermoplastic resin in a circumferential direction, a spiral groove portion is formed in an axial direction on an outer circumferential surface of the base material.

5. The strand according to claim 4, wherein a plurality of the spiral groove portions formed in the same direction and with the same pitch are formed equidistantly in a circumferential direction in a cross section perpendicular to the axial direction.

6. The strand according to claim 4 or 5, wherein a part of an outer periphery in a cross section of the strand perpendicular to the axial direction other than a region of the groove portion is formed by an arc of a same circle, respectively. ​

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