JP2017164928A - Molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding method applicable to a general purpose 3D printer without deteriorating molding precision when using molding material consisting of a fiber bundle.SOLUTION: A three-dimensional molded article is obtained by using a material extrusion type molding device and a linear molding material. As the molding material, a long-sized fiber bundle constituted by gathering a plurality of synthetic fibers is used. In a molding device, molding is conducted at a second discharge rate obtained by multiplying a first discharge rate defined for using a monofilament molding material by a discharge factor K calculated by the following formula (i). K=2500×π×ρ×R×cosθ÷(A×F) (i), where ρ is a specific gravity of a resin constituting the synthetic fiber, π is circular constant, A is total fineness of the synthetic fiber used for the fiber bundle (dtex), θ is an angle formed by a fiber axis of the synthetic fiber to a longer direction of the fiber bundle (degree), F is over feed rate when the fiber bundle is heat treated and R is cross section diameter of the molding material (mm).SELECTED DRAWING: None

Description

  The present invention relates to a modeling method, and more particularly to a material extrusion molding apparatus and a modeling method for obtaining a three-dimensional model using a linear modeling material.

  A 3D printer that creates a three-dimensional object based on a blueprint on a computer can easily produce parts, jigs, and products without using a mold or a large-scale melting device. It is rapidly spreading. In particular, a hot melt lamination type 3D printer using a thermoplastic resin as a modeling material is sold as a low-priced version and is beginning to spread to individuals.

  As a modeling material used for such a hot melt lamination type 3D printer, a linear resin molded product (monofilament-like product) in which a thermoplastic resin is continuous in the longitudinal direction with a diameter of several mm is commercially available and used. Yes. For example, in Patent Document 1, as a highly accurate modeling material, the average diameter is 0.069 to 0.074 inch (about 1.75 to 1.90 mm), the length is 20 feet (about 6.1 m) or more, A modeling material (feed material) having a standard deviation in diameter of 0.0004 inches (0.01 mm) or less is disclosed. As a thermoplastic resin constituting such a modeling material, a thermoplastic resin such as ABS resin, polycarbonate, polyamide, polylactic acid is used.

  The design drawing on the computer is converted into an operation program for the 3D printer by dedicated software called slicer software. With the slicer software, you can set the 3D printer nozzle head movement speed, material discharge speed, material melting temperature, stacking thickness, filling rate, etc. at the time of modeling. Is possible to get

  For example, for commercial desktop 3D printers, the discharge speed is often calculated automatically by slicer software, and the specific values for the discharge speed calculated from the diameter and material information of the modeling material are used depending on the software. Some people cannot read.

JP 2005-523391 A

  The modeling material composed of the above-mentioned continuous linear resin molding (monofilament) is hard and cannot be said to be easy to handle. Among them, the polylactic acid modeling material is particularly hard, such a hard material. As soon as the winding material is slightly loosened from the state of being wound around the bobbin or the like, the modeling material is released from the bobbin and becomes scattered and scattered. Such a state is also called “crash occurrence”. Further, among the polylactic acid modeling materials sold in the market, those that have not been crystallized have a problem that they are easily broken during use.

  In view of such a situation, the present inventor has studied to provide a modeling material for a hot melt lamination method 3D printer with good handleability. In the past, it was common sense to use a so-called monofilament-like material for the material for the hot melt lamination method 3D printer. However, other forms could be applied without being caught by the common sense. Among them, a plurality of synthetic fibers were converged to invent a single continuous thread-shaped modeling material. In various studies using this invention, when modeling using a modeling material made of a fiber bundle, a 3D printer is used under the same conditions as when using a commercially available monofilament modeling material having the same diameter. It has been found that the balance between the discharge speed of the extruder and the movement speed of the nozzle head does not match, and the modeling accuracy may be impaired. Then, as a result of examining improvement in modeling accuracy when using a modeling material composed of a fiber bundling body with a general-purpose 3D printer, the present invention has been reached.

  An object of the present invention is to provide a modeling method that can be applied to a general-purpose 3D printer, and that does not impair modeling accuracy when a modeling material made of a fiber bundle is used.

In order to solve the above-mentioned problem, the first modeling method for a three-dimensional modeled object using a material extrusion molding apparatus and a linear modeling material according to the present invention includes a plurality of synthetic fibers as the modeling material. A discharge coefficient K obtained by the following equation (i) is used as a first discharge speed defined in order to use a monofilament modeling material in the modeling apparatus, using a long-sized fiber bundling body configured by focusing. Modeling is performed at a second discharge speed obtained by multiplication.
K = 2500 × π × ρ × R ² × cos θ ÷ (A × F) (i)
here,
ρ: Specific gravity of resin constituting the synthetic fiber π: Circumferential ratio A: Total fineness (dtex) of the synthetic fiber used for the fiber bundle
θ: Angle (degrees) formed by the fiber axis of the synthetic fiber with respect to the longitudinal direction of the fiber bundle
F: Overfeed rate when the fiber bundle is heat-treated R: Cross-sectional diameter of the modeling material (mm)
It is.

The 2nd modeling method of the three-dimensional molded item using the material extrusion type | mold shaping | molding apparatus and linear modeling material of this invention is the elongate shape comprised by combining a plurality of synthetic fibers as said modeling material. Using a modeling material composed of a plurality of types of fiber bundling bodies or a modeling material composed of a plurality of types of synthetic fibers, the first discharge speed specified for using a monofilament modeling material in the modeling apparatus is as follows: The molding is performed at the second ejection speed obtained by multiplying the ejection coefficient K obtained by the equation (ii).
K = 2500 × π × R ² ÷ F ÷ {(A ₁ ÷ ρ ₁ ÷ cos θ ₁ ) + (A ₂ ÷ ρ ₂ ÷ cos θ ₂ ) +... + (A _n ÷ ρ _n ÷ cos θ _n )} .. (ii)
here,
ρ _n : Specific gravity of the resin constituting the synthetic fiber n π: Circumferential ratio _An : Total fineness (dtex) of the synthetic fiber n used in the fiber bundle
θ _n : angle (degree) formed by the fiber axis of the synthetic fiber n with respect to the longitudinal direction of the fiber bundle
F: Overfeed rate when the fiber bundle is heat-treated R: Cross-sectional diameter of the modeling material (mm)
The subscript 1-n means the number of the synthetic fiber.

  The three-dimensional structure of the present invention is obtained by only the first modeling method or the second modeling method.

  According to the modeling method of the present invention, in a modeling apparatus set to be suitable for using a commercially available monofilament modeling material having the same diameter, even when a modeling material constituted by a fiber bundling body is used, The discharge speed in the extruder and the moving speed of the nozzle head can be balanced, and the required modeling accuracy can be maintained.

  The modeling material used for the hot melt laminating method 3D printer is a material for supplying the hot melt laminating method 3D printer to obtain a three-dimensional modeled object, and is made of a thermoplastic resin. Using this modeling material, the thermoplastic resin constituting the modeling material is melted by heating with the modeling head of the 3D printer based on the design drawing on the computer, and injected and laminated from the nozzle to obtain the tertiary of the desired shape Create the original model.

  This modeling material is composed of thermoplastic synthetic fibers. As the thermoplastic resin constituting the synthetic fiber, any thermoplastic resin that can be melted at the melting temperature of the modeling head in the hot melt lamination method 3D printer can be used. Among them, those having a melting point of 180 ° C. or less are preferable, for example, aliphatic polyester resins, aromatic polyester resins, polyamide resins, polyolefin resins, acrylic resins, polycarbonate resins, acrylonitrile-butadiene-styrene co-polymers. Polymer based resins and fluororesin based resins may be mentioned. A mixture of these resins may be used. Among them, polylactic acid is preferable because warpage hardly occurs, and poly-L lactic acid having a low D-form content is more preferable because it is difficult to be yellowish. By adjusting the D-form content, the melting point of polylactic acid can be adjusted according to the temperature control of the printer, but in order to make it less yellowish, the D-form content is less than 1.5 mol% Good thing. The method for producing a synthetic fiber using the above-described resin is not particularly limited. When manufacturing a fiber using the thermoplastic resin which has crystallinity, it is good to apply an extending process and the relaxation process for controlling a heat shrink in a manufacturing process.

  The modeling material has a single continuous thread-like shape in which a plurality of thermoplastic synthetic fibers are bundled. Examples of the method of bundling a plurality of synthetic fibers include a method of twisting, a method of making a string, a method of heat bonding by heat treatment, and the like. More specifically, a method of twisting and converging a plurality of synthetic fibers, and a method of converging as a braid by using two or more bundles obtained by aligning or twisting a plurality of synthetic fibers , A method of bundling by heat-treating a plurality of synthetic fibers, melting or softening a part of the thermoplastic resin constituting the synthetic fibers, and thermally bonding the fibers, or these A method that combines twisting, string making, and thermal bonding.

  As a specific method for bundling a plurality of synthetic fibers, the method described in Japanese Patent Application No. 2015-24247 by the present applicant may be applied.

  The discharge speed of the 3D printer, which is a modeling apparatus, refers to the amount of resin that is extruded per unit time from the extruder of the hot melt laminated 3D printer. Depending on the three-dimensional model used, the discharge of the extruder during modeling may become discontinuous or increase or decrease. These discharge adjustments are automatically calculated by the above slicer software. In general 3D printers and slicer software, the user may not be able to know or change the discharge speed at each stage in the process, but the overall discharge speed can be changed by changing the conditions of the slicer software. There are many things that can be adjusted with a factor.

In the present invention, a coefficient K by which the discharge speed is multiplied is obtained as follows.
K = 2500 × π × ρ × R ² × cos θ ÷ (A × F) (i)
here,
ρ: Specific gravity of resin constituting the synthetic fiber π: Circumferential ratio A: Total fineness (dtex) of the synthetic fiber used for the fiber bundle
θ: Angle (degrees) formed by the fiber axis of the synthetic fiber with respect to the longitudinal direction of the fiber bundle
F: Overfeed rate when the fiber bundle is heat-treated R: Cross-sectional diameter of the modeling material (mm)
It is.

  The angle θ formed by the fiber axis of the synthetic fiber with respect to the longitudinal direction of the modeling material may mean, for example, the twist angle when the synthetic fiber is twisted. In the formula (i), the synthetic fiber means a synthetic fiber used when the fiber bundle is finally formed. When this synthetic fiber is a single piece of the original synthetic fiber, or a plurality of the original synthetic fibers are bundled and aligned, combined by means such as twisting and entanglement In this case, the angle formed by the fiber axis of the synthetic fiber with respect to the longitudinal direction of the fiber bundle is defined as θ. For example, the fiber bundling body is a braid composed of a plurality of synthetic fibers (a braid angle of 20 degrees), and a plurality of synthetic fibers based on the synthetic fiber are twisted together (a twist angle of 10 degrees). When the angle θ used in the equation (i) is 20 degrees.

When heat treating synthetic fibers, it may be necessary to overfeed to deal with heat shrinkage. The overfeed rate F takes this into consideration. For this reason, the overfeed rate F is usually a value larger than 1. On the other hand, when the fiber is stretched during the heat treatment, underfeed may occur. In this case, the overfeed rate F is a value smaller than 1.

When the modeling material is composed of n types of synthetic fibers (synthetic fiber 1, synthetic fiber 2,..., Synthetic fiber n) in which either θ or ρ in the above formula is different, the discharge coefficient K is as follows: Ask for it.
K = 2500 × π × R ² ÷ F ÷ {(A ₁ ÷ ρ ₁ ÷ cos θ ₁ ) + (A ₂ ÷ ρ ₂ ÷ cos θ ₂ ) +... + (A _n ÷ ρ _n ÷ cos θ _n )} ... (ii)
here,
ρ _n : Specific gravity of the resin constituting the synthetic fiber n π: Circumferential ratio _An : Total fineness (dtex) of the synthetic fiber n used in the fiber bundle
θ _n : angle (degree) formed by the fiber axis of the synthetic fiber n with respect to the longitudinal direction of the fiber bundle
F: Overfeed rate when the fiber bundle is heat-treated R: Cross-sectional diameter of the modeling material (mm)
The subscript 1-n means the number of the synthetic fiber.

  Here, as a modeling material constituted by n types of synthetic fibers, a modeling material constituted by a plurality of long-sized fiber bundling bodies formed by bundling a plurality of synthetic fibers or a plurality of types of synthetic fibers The modeling material comprised by is mentioned.

  When the modeling material is a fiber bundling body constituted by a plurality of types of synthetic fibers having different materials or different single fiber finenesses, the case where the modeling material is a fiber bundling body constituted by monofilament yarns and multifilament yarns, Apply equation (ii).

When modeling using a monofilament-shaped modeling material having a predetermined wire diameter, assuming that the discharge speed for the modeling apparatus (3D printer) is S0, the modeling material having the same wire diameter constituted by the fiber bundling body is used. The modeling speed S when modeling using can be calculated | required by following Formula.
S = K × S0

  In this way, by changing the discharge speed, a long fiber formed by concentrating a plurality of synthetic fibers according to the present invention on a 3D printer that uses a known monofilament as a modeling material. The modeling material currently formed with the converging body can be used appropriately.

  In the following examples and comparative examples, in the evaluation test of the formability by the 3D printer, a SCOOVO C170 type 3D printer manufactured by Abee Corporation was used, and the modeling temperature was 230 ° C., the stacking pitch was 0.1 mm, and the density was 100%. A cube having a side of 3 cm was prepared, and the appearance was visually confirmed.

Reference example 1
Using a polylactic acid monofilament (melting point: 170 ° C.) having a diameter of 1.75 mm as a modeling material, modeling was performed with a 3D printer at the aforementioned discharge coefficient K = 1. When the formability evaluation was performed, it was a shaped article without conspicuous unevenness on the surface.

Comparative Example 1
The plied yarns using a total of 35 560 dtex 96 filament polylactic acid multifilaments (melting point: 170 ° C.) were heat-treated at 165 ° C. for 1 minute. Thereby, a modeling material having a wire diameter of 1.75 mm was obtained.

  Using the obtained modeling material, modeling was performed by a 3D printer with a discharge coefficient K = 1 that does not match Formula (i). When the formability was evaluated, it was a poor shaped article with many irregularities on the surface.

Comparative Example 2
The modeling material used in Comparative Example 1 was modeled by a 3D printer with a discharge coefficient K = 2 that does not match Formula (i). When the formability was evaluated, it was a poor shaped article with irregularities on the surface.

Example 1
The variables for the modeling material used in Comparative Example 1 were as follows. Using this variable, the discharge coefficient K was obtained from the above-described equation (i), and was 1.34. Using this modeling material, modeling was performed by a 3D printer with a discharge coefficient K = 1.34. When the formability was evaluated, it was a shaped article without conspicuous irregularities on the surface.
ρ = 1.24
A = 19,600 dtex
θ = 15 degrees, cos θ = 0.97
F = 1.1
R = 1.75mm

Example 2
A fiber bundle in which 20 polylactic acid multifilaments used in Comparative Example 1 were aligned was placed on the core yarn, and the same multifilament was placed one by one on the side yarn to obtain 16 round braided braids. The braid was heat-treated at 165 ° C. for 1 minute to obtain a modeling material having a wire diameter of 1.75 mm. The variables of this modeling material were as follows. In the following, subscript 1 corresponds to the core yarn, and subscript 2 corresponds to the side yarn. The discharge coefficient K of this modeling material was determined from the above-described formula (ii) and was 1.21. Using this modeling material, modeling was performed by a 3D printer with a discharge coefficient K = 1.21. When the formability was evaluated, it was a shaped article without conspicuous irregularities on the surface.
ρ ₁ = 1.24
A ₁ = 11,200 dtex
θ ₁ = 0 degree, cos θ ₁ = 1.00
ρ ₂ = 1.24
A ₂ = 8,960 dtex
θ ₂ = 15 degrees, cos θ ₂ = 0.97
F = 1.2
R = 1.75mm

Example 3
Various twisted yarns using a total of 18 polylactic acid multifilaments used in Comparative Example 1 were placed in the core yarn, and the same multifilaments were placed one by one in the side yarn to obtain 16 round braided braids. The braid was heat-treated at 165 ° C. for 1 minute to obtain a modeling material having a wire diameter of 1.75 mm. The variables of this modeling material were as follows. In the following, subscript 1 corresponds to the core yarn, and subscript 2 corresponds to the side yarn. The discharge coefficient K of this modeling material was determined from the formula (ii) to be 1.24. Using this modeling material, modeling was performed with a discharge coefficient K = 1.24 using a 3D printer. When the formability was evaluated, it was a shaped article without conspicuous irregularities on the surface.
ρ ₁ = 1.24
A ₁ = 10,080 dtex
θ ₁ = 15 degrees, cos θ ₁ = 0.97
ρ ₂ = 1.24
A ₂ = 8,960 dtex
θ ₂ = 20 degrees, cos θ ₂ = 0.94
F = 1.2
R = 1.75mm

Example 4
Various twisted yarns using a total of 18 polylactic acid multifilaments used in Comparative Example 1 and 9 560 dtex 96 filament isophthalic acid copolyester multifilaments (melting point 160 ° C.) as core yarns. And 16 round punched braids were obtained in which the polylactic acid multifilaments were arranged one by one on the side threads. The braid was heat-treated at 165 ° C. for 1 minute to obtain a modeling material having a wire diameter of 1.75 mm. The variables of this modeling material were as follows. In the following, subscript 1 corresponds to the polyfilament made of polylactic acid as the core yarn, subscript 2 corresponds to the multifilament made of isophthalic acid copolymer polyester as the core yarn, and subscript 3 corresponds to the side yarn. The discharge coefficient K of this modeling material was determined from the formula (ii) and was 1.28. When this modeling material was modeled by a 3D printer with a discharge coefficient K = 1.28 and the modeling property was evaluated, it was a modeled object without conspicuous irregularities on the surface.
ρ ₁ = 1.24
A ₁ = 5,040 dtex
θ ₁ = 15 degrees, cos θ ₁ = 0.97
ρ ₂ = 1.38
A ₂ = 5,040 dtex
θ ₂ = 15 degrees, cos θ ₂ = 0.97
ρ ₃ = 1.24
A ₃ = 8,960 dtex
θ ₃ = 20 degrees, cos θ ₂ = 0.94
F = 1.2
R = 1.75mm

Claims (3)

A method for modeling a three-dimensional model using a material extrusion molding apparatus and a linear modeling material, wherein a long-sized fiber bundling body configured by bundling a plurality of synthetic fibers is used as the modeling material. The modeling is performed at the second discharge speed obtained by multiplying the first discharge speed defined for using the monofilament modeling material in the modeling apparatus by the discharge coefficient K obtained by the following equation (i). A characteristic modeling method.
K = 2500 × π × ρ × R ² × cos θ ÷ (A × F) (i)
here,
ρ: Specific gravity of resin constituting the synthetic fiber π: Circumferential ratio A: Total fineness (dtex) of the synthetic fiber used for the fiber bundle
θ: Angle (degrees) formed by the fiber axis of the synthetic fiber with respect to the longitudinal direction of the fiber bundle
F: Overfeed rate when the fiber bundle is heat-treated R: Cross-sectional diameter of the modeling material (mm)
It is. A method for modeling a three-dimensional model using a material extrusion molding apparatus and a linear modeling material, and a plurality of long-sized fiber bundling configured by bundling a plurality of synthetic fibers as the modeling material Using a modeling material constituted by a body or a modeling material constituted by a plurality of types of synthetic fibers, the following equation (ii) is applied to a first discharge speed defined for using a monofilament modeling material in the modeling apparatus: A modeling method characterized in that modeling is performed at a second ejection speed obtained by multiplying the ejection coefficient K obtained by the above.
K = 2500 × π × R ² ÷ F ÷ {(A ₁ ÷ ρ ₁ ÷ cos θ ₁ ) + (A ₂ ÷ ρ ₂ ÷ cos θ ₂ ) +... + (A _n ÷ ρ _n ÷ cos θ _n )} .. (ii)
here,
ρ _n : Specific gravity of the resin constituting the synthetic fiber n π: Circumferential ratio _An : Total fineness (dtex) of the synthetic fiber n used in the fiber bundle
θ _n : angle (degree) formed by the fiber axis of the synthetic fiber n with respect to the longitudinal direction of the fiber bundle
F: Overfeed rate when the fiber bundle is heat-treated R: Cross-sectional diameter of the modeling material (mm)
The subscript 1-n means the number of the synthetic fiber.   A three-dimensional modeled object obtained only by the modeling method according to claim 1 or 2.