Strand and method for manufacturing strand

Abstract

To provide a resin strand with superior bendability, enabling smooth building by a three-dimensional printer.SOLUTION: A resin strand 1 is linearly formed and used as a build material for a three-dimensional printer. The strand has an outer peripheral face in which a spiral groove portion 9 is formed along an axial direction.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a strand and a method for manufacturing the strand Regarding. [Background technology]

[0002] As a device for forming objects with three-dimensional shapes, 3D (three-dimensional) printers that use fused deposition modeling, in which resin that has been plasticized by heat is stacked layer by layer, are known. This 3D printer can form three-dimensional objects without the need for molds or jigs. In addition, it can also form three-dimensional objects that are difficult to form using injection molding technology.

[0003] As shown in FIG. 12, there is a 3D printer in which a straight resin strand (filament) 203 wound around a spool 201 is continuously fed to a nozzle 207 through a tube 205, and the strand 203 is plasticized by the heat of a heater and then ejected from the nozzle 207 and layered on a base 209 (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-123241 A Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, in the above-mentioned 3D printer, if there is a bent point K in the supply path of the strand 203 fed from the spool 201 to the nozzle 207, a bending force is applied to the strand 203 at this bent point K, which may cause the strand 203 to be broken or damaged.

[0006] Therefore, the present invention is a resin strand with excellent bendability that can be smoothly modeled using a 3D printer. and a method for manufacturing the strandThe purpose is to provide. [Means for solving the problem]

[0007] The present invention comprises the following configurations. A linear resin strand used as a modeling material for a 3D printer, A spiral groove is formed on the outer circumferential surface along the axial direction. Strand. Effect of the Invention

[0008] According to the present invention, it is possible to provide a resin strand with excellent bendability that can be smoothly modeled using a 3D printer. [Brief description of the drawings]

[0009] [Figure 1A] FIG. 2 is a perspective view of a strand according to the present embodiment. [Figure 1B] FIG. 2 is a cross-sectional view perpendicular to the longitudinal direction of the strand according to the present embodiment. [Diagram 2] FIG. 1 is an overall configuration diagram of a manufacturing device for manufacturing a strand according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a front view of a die provided in a strand drawing section of a resin bath section constituting the manufacturing apparatus. [Figure 4] FIG. 13 is a perspective view of a strand of another construction. [Diagram 5] FIG. 13 is a perspective view of a strand of another construction. [Figure 6] FIG. 13 is a perspective view of a strand of another construction. [Figure 7] FIG. 13 is a perspective view of a strand of another construction. [Figure 8] FIG. 13 is a perspective view of a strand of another construction. [Figure 9] FIG. 13 is a perspective view of a strand of another construction. [Figure 10] FIG. 2 is a schematic cross-sectional view showing an enlarged view of a portion of the outer peripheral surface of the strand. [Figure 11]FIG. 13 is a perspective view of a strand of another construction. [Figure 12] FIG. 1 is a schematic diagram of a 3D printer using resin strands. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. (Strand) FIG. 1A is a perspective view of a strand according to this embodiment, and FIG. 1B is a cross-sectional view perpendicular to the longitudinal direction of the strand according to this embodiment.

[0011] As shown in FIG. 1A and FIG. 1B, the strand 1 according to this embodiment is a linear resin material used as a modeling material for a 3D printer. The strand 1 has a base material 3 mainly composed of a thermoplastic resin, and a plurality of fiber bundles 5 impregnated in the base material 3 and extending continuously in the axial direction. The fiber bundle 5 is a bundle of a plurality of fibers 7, which are arranged in the center of the strand 1 in a twisted state. In this example, there are three fiber bundles 5, which are twisted together. The outer periphery of the base material 3, and therefore the outer periphery of the strand 1, is formed in a substantially circular shape in a vertical cross section in the longitudinal direction (axial direction) of the strand 1, except for a groove portion 9 described later.

[0012] The strand 1 has a plurality of grooves 9 (three in this example) on its outer circumferential surface. These grooves 9 are formed in a spiral shape along the axial direction. The grooves 9 are formed at equal intervals in the circumferential direction in a cross section perpendicular to the axial direction, and it is preferable that the spiral direction and the spiral pitch P are the same. The spiral pitch P of the grooves 9 is preferably 0.001 mm to 500 mm, and particularly preferably 0.005 mm to 100 mm. The width dimension Wa of the grooves 9 is preferably 0.001 mm to 10 mm, and particularly preferably 0.005 mm to 5 mm. The depth dimension H of the grooves 9 is preferably 0.001 mm to 10 mm, and particularly preferably 0.005 mm to 1 mm.

[0013] 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. The ratio (P / Wa) of the pitch P to the width dimension Wa of the groove portion 9 is preferably 0.0001 to 500,000, more preferably 0.01 to 50,000, and particularly preferably 0.1 to 5000. By keeping it within the above range, the bendability of the strand 1, which will be described later, can be improved.

[0014] A 3D printer using the strand 1 employs a so-called fused deposition modeling method, which forms a three-dimensional object by gradually stacking strands 1 in which a thermoplastic resin component is melted by heat. In this fused deposition modeling method, a layer is formed one by one while adhering a previously formed layer to the next layer in a semi-solid (softened) state. There are no particular limitations on this 3D printer, so long as it can form an object by gradually stacking resin in a plasticized state by heat. For example, a 3D printer can be one that includes a support plate that can be freely moved in the up-down, left-right, and front-back directions, and a supply unit that supplies the thermoplastic resin component of the strand 1 to the support plate while plasticizing it.

[0015] Organic fibers such as polyethylene fibers, aramid fibers, and Zylon fibers, and inorganic fibers such as boron fibers, glass fibers, carbon fibers, metal fibers, and rock fibers can be used for the fiber bundles 5 constituting the strand 1. Surface-treated fibers can be used for the reinforcing fibers to improve the adhesive strength between the resin and the fibers.

[0016] The thermoplastic resin which is the main component of the substrate 3 can be a polyolefin resin such as polypropylene or polyethylene, a polyester resin such as acrylonitrile-butadiene-styrene resin, polystyrene resin, polyethylene terephthalate, polybutylene terephthalate or polylactic acid, a polyamide resin, an aromatic polyamide resin, polyetherimide, polyarylimide, polyarylate, polyether ether ketone, polyaryl ether ketone, polybenzimidazole, polyethersulfone, polysulfone, polyvinylidene fluoride resin, liquid crystal polymer, a polycarbonate resin, polyacetal, or polyphenylene sulfide.

[0017] These resins may be used alone, or a thermoplastic resin blend of multiple resins may be used 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 part. Examples include PEEK / PTFE, PEEK / PBI, etc. Also, resins to which short fibers such as carbon fiber and glass fiber, talc, etc. have been added can be used.

[0018] The durability of the molded object can be improved by adding antioxidants such as phenols, thioethers, and phosphites, UV absorbers such as benzotriazoles and triazines, and metal deactivators such as hydrazides and amides to the thermoplastic resin.

[0019] By adding a plasticizer such as a phthalic acid-based or polyester-based plasticizer, the flexibility of the thermoplastic resin can be improved, thereby improving the molding accuracy during molding and the flexibility of the molded object.

[0020] By adding halogen-based, phosphate-based, inorganic, or intumescent flame retardants to thermoplastic resins, the flame retardancy of the molded object can be improved.

[0021] By adding core materials such as phosphate metal salts and sorbitol to thermoplastic resins, thermal expansion during molding can be controlled, improving molding accuracy.

[0022] The antistatic properties of the molded object can be improved by adding a permanent antistatic agent such as a nonionic, anionic, or cationic agent to the thermoplastic resin.

[0023] By adding a hydrocarbon-based, metal soap-based or other lubricant to the thermoplastic resin to improve the lubrication of the continuous fiber reinforced strand, the strand can be more easily delivered during molding.

[0024] In a 3D printer that uses linear resin strands to create objects, the strands are fed from a spool toward a nozzle when creating an object. If there is a bent point in the supply path of the strands, bending force is applied to the strands at the bent point, which may cause the strands to break or become damaged.

[0025] In recent years, a method for fabricating fiber-reinforced plastics (FRP) using a fused deposition modeling (FDM) 3D printer with continuous fiber-reinforced strands reinforced by fibers has been proposed to improve the mechanical strength of the object, and its applications are expanding. However, when fabricating an object using existing continuous fiber-reinforced strands, the flexibility of the continuous fiber-reinforced strands is low in areas with large curvature (small radius of curvature), and fiber peeling, in which the internal fibers peel off, may occur. This causes a difference between the designed path and the path actually taken during fabrication, resulting in a decrease in the fabrication accuracy of the object, and also the occurrence of voids in the object, which may result in a decrease in quality. These decreases in fabrication accuracy and quality tend to occur more significantly when strands with a large diameter are used.

[0026] In contrast, according to the strand 1 of this embodiment, a spiral groove portion 9 is formed on the outer peripheral surface along the axial direction, so that the surface area on the outer peripheral surface can be increased and the bendability can be improved. As a result, when the strand 1 is fed from the spool to the nozzle in the 3D printer, even if a bending force is applied at the bent portion because the supply path has a bent portion, the strand 1 can be fed along the bent supply path without being broken or damaged. Therefore, modeling by the 3D printer can be performed smoothly. In addition, the strand can be easily wound around the spool without being broken or damaged.

[0027] Moreover, since a plurality of spiral grooves 9 are formed, the bendability can be further improved. Also, since a plurality of grooves 9 are formed at equal intervals in the circumferential direction in a vertical cross section in the axial direction of the strand 1, and the spirals of these grooves 9 are in the same direction and have the same pitch, the bendability can be improved in a well-balanced manner in all directions. Furthermore, breakage and damage to the strand at the bend can be avoided without considering the positions of the grooves 9 in the strand 1 and the bending direction of the bent portion of the supply path.

[0028] Furthermore, the strength of the strand 1 can be significantly increased by the fiber bundle 5 in which the fibers 7 are bundled, but the inclusion of the fiber bundle 5 makes the strand 1 less likely to bend. However, good bendability can be ensured by the spiral groove 9 formed on the outer circumferential surface. Furthermore, as a secondary effect of providing such a spiral groove 9, the strand 1 can be bent well while being molded even when a molded object is molded using a fused deposition modeling 3D printer, suppressing deterioration in the molding accuracy of the molded object and deterioration in quality due to the occurrence of voids in the molded object, and enabling the molding of a high-quality object.

[0029] Moreover, since a plurality of fiber bundles 5 each formed by bundling fibers 7 are twisted together, the bendability of the fiber bundles 5 themselves can be improved, and a decrease in bendability due to the inclusion of fiber bundles can be suppressed.

[0030] (manufacturing equipment) Next, an example of a manufacturing apparatus for manufacturing the strand 1 according to this embodiment will be described. FIG. 2 is a diagram showing the overall configuration of a manufacturing apparatus 100 for manufacturing the strand 1 according to this embodiment. 2, the manufacturing apparatus 100 includes a fiber material supplying 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 unwound from the fiber material supplying section 11 is impregnated with the thermoplastic resin R that becomes the substrate 3 by the resin bath section 13 to form the strand 1, which is then drawn out. The strand 1 drawn out from the resin bath section 13 is then cooled by the cooling section 15 while being rotated around its axis by the twisting section 17, and is then taken up by the twisting section 17.

[0031] The fiber material supply section 11 includes a plurality of spools 21 (three in this example) and a plurality of guide rollers 23. A fiber bundle 5 is wound around each of the spools 21, and the fiber bundles 5 are fed out from these spools 21. The fiber bundles 5 fed out from the spools 21 are aligned at intervals by the guide rollers 23 and guided to the resin bath section 13.

[0032] The resin bath section 13 is provided with a cylindrical resin bath 25 extending vertically, in which molten thermoplastic resin R is stored. The resin bath 25 is provided with a kneading extruder (not shown) that melts the thermoplastic resin R raw material introduced and extrudes it into the resin bath 25, and the molten thermoplastic resin R is supplied from the kneading extruder. The resin bath 25 has a fiber bundle inlet 27 at its upper part, and the fiber bundle 5 is fed through the fiber bundle inlet 27. The resin bath 25 also has a strand pull-out section 29 on the side at its lower end, and the strand 1 in which the base material 3 is impregnated with the fiber bundle 5 is pulled out laterally from the strand pull-out section 29.

[0033] Resin bath 25 of resin bath section 13 is provided therein with an impregnation roller 41 and an introduction roller 45, each of which is supported rotatably about a horizontal axis. A plurality of impregnation rollers 41 are provided along the vertical direction within resin bath 25, and introduction roller 45 is provided at the lower end within resin bath 25.

[0034] The three fiber bundles 5 fed from the fiber bundle inlet 27 of the resin bath 25 are alternately wrapped around and in contact with the impregnation roller 41. This causes each fiber bundle 5 to travel in a meandering manner within the resin bath 25. Note that the impregnation roller 41 does not necessarily have to be rotatable. The fiber bundle 5 is wrapped around an introduction roller 45 at the lower end of the resin bath 25, and its travel path is changed from the vertical direction to the horizontal direction and it is guided to the strand pull-out section 29.

[0035] A die 55 is provided in the strand drawing section 29 from which the strand 1 in which the base material 3 is impregnated with the fiber bundle 5 is drawn. The die 55 has a circular opening 57 that narrows in the drawing direction of the strand 1. As shown in FIG. 3, the inner diameter of the opening 57 on the drawing direction side is formed to a size corresponding to the outer diameter of the strand 1 to be produced. The die 55 also has a plurality of (three in this example) groove forming projections 59 that protrude inward on the inner peripheral surface of the opening 57. These groove forming projections 59 are preferably formed at equal intervals in the circumferential direction in a vertical cross section in the drawing direction of the strand 1.

[0036] 3 shows an example in which groove-forming protrusions 59 of die 55 are formed at equal intervals in the circumferential direction in a cross section perpendicular to the drawing direction of strand 1, but groove-forming protrusions 59 do not necessarily have to be formed at equal intervals. If groove-forming protrusions 59 are not formed at equal intervals, the pitch of grooves 9 will not be equal, but by forming grooves 9, it is possible to improve the flexibility of strand 1 compared to a case in which grooves 9 are not formed.

[0037] As described later, a die without groove forming projections 59 may be used.

[0038] The cooling section 15 has a long cooling tank 31 along the drawing direction of the strand 1 drawn from the strand drawing section 29 of the resin bath section 13. Cooling water W is stored inside this cooling tank 31 as a cooling medium. The strand 1 is drawn into the cooling tank 31 from the resin bath section 13 side. The strand 1 drawn into the cooling tank 31 has the thermoplastic resin R that becomes the base material 3 cooled and hardened by the cooling water W stored in the cooling tank 31. The strand 1, in which the thermoplastic resin R has been cooled and hardened by the cooling water W, is drawn out from the twisting section 17 side of the cooling tank 31.

[0039] The twisting section 17 has a pull-in roller 35, a winding bobbin 37, and a case 39. The pull-in rollers 35 are provided on the cooling section 15 side of the case 39, and are arranged in pairs so as to face each other. These pull-in rollers 35 pull the strand 1 from the cooling section 15 into the case 39. The winding bobbin 37 is rotated about an axis perpendicular to the extension direction of the strand 1. As a result, the winding bobbin 37 winds up the strand 1 pulled into the case 39 by the pull-in roller 35. The case 39 is rotated about an axis along the extension direction of the strand 1. As a result, the strand 1 pulled out from the resin bath section 13, passed through the cooling section 15, and wound around the winding bobbin 37 of the twisting section 17 is rotated around the axis to be twisted. Various mechanisms can be used as a means for twisting the strand 1. For example, the twisting means may be a pair of rollers that rotate in different directions, and take up the strand 1 and send it downstream, thereby twisting the strand 1.

[0040] (Manufacturing method) Next, an example of a method for producing the strand 1 by the production apparatus 100 will be described. In the manufacturing apparatus 100, the strand 1 is manufactured by carrying out an impregnation step, a twisting step, a cooling step, and a winding step.

[0041] (1) Impregnation process The impregnation process is a process in which the fiber bundle 5 is impregnated with the thermoplastic resin R by the resin bath section 13 of the manufacturing apparatus 100. In this impregnation process, the fiber bundle 5, which is unwound from the fiber material supply section 11 and introduced from the fiber bundle inlet 27 of the resin bath section 13, passes through the resin bath section 13, whereby the fiber bundle 5 is impregnated with the molten thermoplastic resin R stored inside the resin bath 25.

[0042] Each fiber bundle 5 is alternately hung on a plurality of impregnation rollers 41, and the fibers 7 constituting each fiber bundle 5 are opened by running while being in contact with the outer circumferential surfaces of these impregnation rollers 41. As a result, the fiber bundle 5 is sufficiently impregnated with the thermoplastic resin R between each fiber 7.

[0043] (2) Twisting process The twisting process is a process of twisting together fiber bundles 5 impregnated with thermoplastic resin R. The fiber bundles 5 are wound around the introduction roller 45 with a gap between them, and the running trajectory is changed to a horizontal direction and the fiber bundles are guided to the strand pull-out section 29. At this time, the strand 1 drawn out to the downstream side of the resin bath section 13 is rotated about its axis by the twisting section 17. As a result, the fiber bundles 5 are twisted together from a spaced-apart state as they move from the introduction roller 45 to the strand pull-out section 29.

[0044] The fiber bundles 5 to be twisted are gathered in the center of the opening 57 of the die 55, whereby the outer periphery of the twisted fiber bundles 5 is evenly covered in the circumferential direction with the thermoplastic resin R. Therefore, the strands 1 are pulled out from the opening 57 of the die 55 in such a way that the outer periphery of the twisted fiber bundles 5 is evenly covered with the base material 3 made of the thermoplastic resin R, and the fibers 7 constituting the fiber bundles 5 are not exposed from the outer periphery (see FIG. 3).

[0045] Furthermore, when the strand 1 is drawn out from the opening 57 of the die 55, grooves 9 are formed on the outer circumferential surface of the strand 1 by groove forming protrusions 59 of the opening 57 of the die 55. At this time, the strand 1 is rotated about its axis by the twisting section 17, so that the grooves 9 on the outer circumferential surface are each formed in a spiral shape. As will be described later, a die without groove forming protrusions 59 may be used, in which case grooves 9 are formed in the substrate 3 simply by twisting the strand 1.

[0046] (3) Cooling process The cooling step is a step of cooling the strand 1 by the cooling section 15. In this cooling step, the strand 1 drawn out from the strand drawing section 29 of the resin bath section 13 is drawn into the cooling tank 31 of the cooling section 15, and then drawn out. As a result, the thermoplastic resin R that becomes the base material 3 of the strand 1 is cooled and hardened by the cooling water W stored in the cooling tank 31.

[0047] (4) Winding process The winding process is a process in which the strand 1 is wound around the twisting unit 17. In this winding process, the strand 1 cooled in the cooling unit 15 is drawn into the case 39 by the drawing-in roller 35 of the twisting unit 17, and is wound around the winding bobbin 37 inside the case 39.

[0048] In this manner, in the manufacturing apparatus 100, the above-mentioned steps can easily produce a strand 1 having excellent flexibility with the spiral groove 9 formed on the outer circumferential surface.

[0049] The structure of the strand 1 is not limited to the above embodiment. For example, in the above embodiment, the strand 1 having three fiber bundles 5 is exemplified, but the number of fiber bundles 5 is not limited to three. After the strand 1 having a circular cross section is manufactured, the spiral groove portion 9 may be formed on the outer circumferential surface of the strand 1 by cutting or the like.

[0050] Strands of other structures will be described below. 4 to 8 are perspective views of strands having other structures.

[0051] The strand 1A shown in Fig. 4 has a fiber bundle 5 consisting of a plurality of fibers 7 bundled together. This fiber bundle 5 is provided at the center of the substrate 3 and extends along the axial direction while rotating along the groove 9. Note that the outer periphery of the substrate 3, and therefore the outer periphery surface of the strand 1A, is formed in a substantially circular shape in a cross section perpendicular to the axial direction, except for the groove 9, similar to the strand 1. In other words, the fiber bundle 5 is provided in a region within a concentric circle with respect to the outer periphery surface of the strand 1A.

[0052] The strand 1B shown in Fig. 5 has a reduced circumferential width dimension of the groove portions 9 of the strand 1A shown in Fig. 4, and an increased number of the groove portions 9. By narrowing the circumferential arrangement pitch of the groove portions 9, the bendability of the strand 1B is improved and the bending resistance can be made uniform regardless of the bending direction.

[0053] In the strand 1C shown in FIG. 6, the fiber bundles 5 of the strand 1B shown in FIG. 5 are replaced with three (multiple) fiber bundles 5. The multiple fiber bundles 5 are each arranged at positions that are point symmetrical with respect to the center of the strand 1B. In this case as well, the bendability and uniformity of the bending resistance of the strand 1C are improved. In this case, even if it is difficult to form grooves by twisting as in the case of the strand 1D in FIG. 7 described later due to reasons such as the relatively hard substrate 3, the grooves 9 can be reliably formed.

[0054] The strand 1D shown in FIG. 7 is a strand manufactured using three (multiple) fiber bundles 5. A die without groove-forming protrusions 59 is used to manufacture the strand 1D in this case. The strand 1D has grooves 9 formed by twisting the strand 1D itself, and in turn, the three (multiple) fiber bundles 5 themselves. Therefore, in the strand 1D, the grooves 9 formed on the outer circumferential surface are not concave, but V-shaped. These grooves 9 are also formed in a spiral shape, and the inner surface is formed so as to smoothly connect to the outer circumferential surface of the strand 1D. In this case, since the grooves 9 are formed by twisting the fiber bundles 5 themselves, there is no need to separately process the grooves 9, and the manufacturing process can be simplified.

[0055] As other examples in which grooves are formed by twisting the strands themselves, and in turn the fiber bundles themselves, using a die without groove forming projections 59, strand 1E in FIG. 8 and strand 1F in FIG.

[0056] 8 contains a single fiber bundle 5. The strand 1E has a groove 9 formed by twisting the strand 1E itself, and in turn the single fiber bundle 5 contained therein. The fiber bundle 5 in this case is provided at the center of the substrate 3, and extends in the axial direction while rotating along the groove 9.

[0057] Further, strand 1F shown in Fig. 9 contains multiple fiber bundles 5 and has the same configuration as strand 1E shown in Fig. 8. However, strand 1F has a greater degree of twist (narrower helical pitch) than strand 1E. As a result, the depth of groove portion 9 is deeper in strand 1F than in strand 1E. As a result, while the cross section of strand 1D shown in Fig. 7 has an irregular shape that is a combination of three circles, the cross section of strand 1F is formed into a shape that is closer to a circle.

[0058] Fig. 10 is a schematic cross-sectional view showing, in an enlarged scale, a cross-sectional shape perpendicular to the axial direction of the strands 1E and 1F shown in Fig. 8 and Fig. 9. Note that Fig. 10 shows the grooves 9 in a schematic manner, and the depth dimension H of the grooves 9, the width dimension Wa of the grooves 9, and the circumferential distance L between the grooves 9 are examples. The outer peripheral surface of the strand shown in FIG. 10 (outer peripheral surface 3a of the substrate 3) is formed in a substantially circular cross-sectional shape, similar to the strand 1, except for the region between the circumferential ends 9a, 9b of the same groove portion 9. The substantially circular shape here means a circular shape or a shape close to a circular shape, and specifically means a shape in which the outer peripheral edge in a vertical cross section in the axial direction of the strand 1, excluding the region of the groove portion 9, is formed by arcs of the same circle. In addition, each arc does not necessarily have to be an arc of the same circle, and each arc may be disposed including a specific radial position from the center of the strand 1. Alternatively, it is sufficient that the circle circumscribing each arc is concentric with the center of the strand 1. The shape of the outer peripheral surface of the strand other than the groove portion 9 is the same for the strands 1, 1A, 1B, and 1C shown in FIGS. 1A, 1B, and 4 to 6.

[0059] 11 does not include fiber bundles 5, and is composed only of a base material 3 made of a thermoplastic resin. In this case as well, the outer periphery of the base material 3, and therefore the outer periphery of the strand 1G, is formed in a substantially circular shape in a cross section perpendicular to the axial direction, except for the groove portion 9, as described above.

[0060] Each of the strands 1A, 1B, 1C, 1D, 1E, 1F, and 1G described above has a spiral groove 9 formed along the axial direction on the outer circumferential surface, which increases the surface area on the outer circumferential surface and improves bendability. In addition, for each strand, in order to ensure sufficient strength of the molded object, the fiber volume content, which is the ratio of fibers to the entire strand, is preferably 5% or more and 85% or less.

[0061] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates mutual combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known technologies, and these are included in the scope of protection sought.

[0062] As described above, the present specification discloses the following: (1) A linear resin strand used as a modeling material for a 3D printer, A strand having an axially extending spiral groove formed on its outer circumferential surface. According to this strand, a spiral groove is formed on the outer circumferential surface along the axial direction, so that the surface area of ​​the outer circumferential surface can be increased and bendability can be improved. As a result, when the strand is fed from the spool to the nozzle in the 3D printer, even if a bending force is applied at the bent point because the supply path has a bent portion, the strand can be fed along the bent supply path without being broken or damaged. Therefore, modeling can be performed smoothly using the 3D printer. In addition, the strand can be easily wound around the spool without being broken or damaged.

[0063] (2) The strand according to (1), wherein a plurality of the grooves formed in a spiral shape with the same direction and pitch are formed at equal intervals in the circumferential direction in a cross section perpendicular to the axial direction. According to this strand, since a plurality of helical grooves are formed, the bendability can be further improved. In addition, since the plurality of grooves are formed at equal intervals in the circumferential direction in a cross-sectional view and the helices of these grooves are in the same direction and have the same pitch, the bendability can be improved in a balanced manner in all directions.

[0064] (3) The strand according to (1) or (2), comprising a plurality of fibers or fiber bundles along the axial direction. With this strand, the strength can be significantly increased by the fibers or fiber bundles. In addition, the inclusion of fibers or fiber bundles makes the strand less likely to bend, but the spiral grooves formed on the outer circumferential surface ensure good bendability. This allows the strand to be bent well when molding an object using a fused deposition modeling 3D printer, suppressing deterioration in molding accuracy and quality degradation due to the occurrence of voids in the object, allowing the creation of high-quality objects.

[0065] (4) The strand according to (3), wherein the fibers or fiber bundles are twisted together. According to this strand, since the fibers or fiber bundles are twisted together, the bendability of the fibers or fiber bundles themselves can be increased, and a decrease in bendability due to the inclusion of the fibers or fiber bundles can be suppressed.

[0066] (5) The strand according to any one of (1) to (4), wherein the outer peripheral edge of the strand in a vertical cross section in the axial direction, excluding the groove region, is formed by arcs of the same circle. With this strand, the outer edge of the cross section is formed by an arc of the same circle, and the outer surface as a whole is formed in an approximately circular shape. Therefore, when creating an object using a 3D printer, for example, the supply amount of strand can be kept constant, and the quality of the object can be stabilized. [Explanation of symbols]

[0067] 1, 1A, 1B, 1C strands 5 Fiber bundle 7. Fiber 9 Groove

Claims

1. A linearly formed strand used as a modeling material for a 3D printer, A substrate including a thermoplastic resin; A single fiber bundle provided at the center of the substrate, in which a plurality of fibers are bundled and continuously extend in the axial direction; having The fibers of the fiber bundle are twisted, and the thermoplastic resin is impregnated between the fibers, The outer periphery of the fiber bundle is covered in the circumferential direction with the thermoplastic resin, and a spiral groove portion is formed in the outer circumferential surface of the thermoplastic resin along the axial direction. Strand.

2. A plurality of the grooves formed in a spiral shape having the same direction and the same pitch are formed at equal intervals in the circumferential direction in a cross section perpendicular to the axial direction. The strand of claim 1.

3. A linearly formed strand used as a modeling material for a 3D printer, A substrate including a thermoplastic resin; A plurality of fiber bundles are provided at the center of the base material, each bundle including a plurality of fibers bundled together and extending continuously in the axial direction; having The plurality of fiber bundles are twisted together with each other such that the fibers of each fiber bundle are twisted and the thermoplastic resin is impregnated between the fibers, and an outer periphery of the twisted fiber bundle is covered in a circumferential direction with the thermoplastic resin, A spiral groove is formed on the outer peripheral surface of the thermoplastic resin along the axial direction. Strand.

4. A plurality of the grooves formed in a spiral shape with the same direction and the same pitch are formed at equal intervals in the circumferential direction in a vertical cross section in the axial direction. The strand of claim 3.

5. The outer circumferential edge of the strand in a vertical cross section in the axial direction, except for the groove region, is formed by arcs of the same circle. A strand according to any one of claims 1 to 4.

6. A linearly formed strand used as a modeling material for a 3D printer, A substrate including a thermoplastic resin; A single fiber bundle provided at the center of the substrate, in which a plurality of fibers are bundled and continuously extend in the axial direction; A method for producing a strand having the following structure: The fiber bundle is passed through a resin bath section in which a molten thermoplastic resin is stored, so that the thermoplastic resin is impregnated between the fibers of the fiber bundle; a step of drawing out the fiber bundle impregnated with the thermoplastic resin from a die provided in the resin bath section while rotating the fiber bundle about an axis to impart a twist thereto, thereby forming a strand in which an outer periphery of the fiber bundle is covered with the thermoplastic resin, The die has an opening that narrows in a direction in which the strand is drawn out, and an inner circumferential surface of the opening is provided with a plurality of groove-shaped protrusions that protrude inward from the inner circumferential surface, When the fiber bundle covered with the thermoplastic resin passes through the groove-shaped protrusion, a plurality of spiral grooves are formed in the axial direction on the outer peripheral surface of the thermoplastic resin by the groove-shaped protrusion. A method for manufacturing strands.

7. A linearly formed strand used as a modeling material for a 3D printer, A substrate comprising a thermoplastic resin; A plurality of fiber bundles are provided at the center of the base material, each bundle including a plurality of fibers bundled together and extending continuously in the axial direction; A method for producing a strand having the following structure: The fiber bundles are passed through a resin bath in which a molten thermoplastic resin is stored, thereby impregnating the thermoplastic resin between the fibers of the fiber bundles; a step of drawing out the plurality of fiber bundles impregnated with the thermoplastic resin from a die provided in the resin bath section while rotating the plurality of fiber bundles about an axis to impart twist thereto, thereby forming a strand in which the outer periphery of the plurality of fiber bundles is covered with the thermoplastic resin, The die has an opening that narrows in a direction in which the strand is drawn out, and an inner circumferential surface of the opening is provided with a plurality of groove-shaped protrusions that protrude inward from the inner circumferential surface, A plurality of fiber bundles covered with the thermoplastic resin pass through the groove-shaped protrusions, thereby forming a plurality of spiral grooves along the axial direction on the outer peripheral surface of the thermoplastic resin by the groove-shaped protrusions. A method for manufacturing strands.

8. The grooves are formed in a spiral shape having the same direction and pitch, and are equally spaced in the circumferential direction in a vertical cross section in the axial direction. A method for producing the strand according to claim 6 or 7.

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