JP2019136925A - Three dimensional modeling method and three dimensional modeling apparatus - Google Patents

Abstract

To minimize a use amount of an expensive core material while satisfying material characteristics and mechanical properties required for a three-dimensional modeled products.SOLUTION: According to a three-dimensional modeling method and a three-dimensional modeling apparatus of the present invention, a three-dimensional modeled product having a desired shape is obtained by the following process: a molded shell having a cavity inside and/or a recess on an outer surface is molded using a first molding material (shell material) and subsequently the cavity and/or the recess of the molded shell are filled using a second molding material (core material).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a three-dimensional modeling method and apparatus such as a so-called 3D printer whose performance has been remarkably improved in recent years, or a modeling apparatus using an optical modeling technique that has been put into practical use before that. It is related to the three-dimensional modeling technology of the composite material containing.

  A so-called 3D printer calculates the cross-sectional shape of a modeled object with a computer based on three-dimensional CAD data, divides the modeled object into thin, round-shaped cross-sectional components, and forms the cross-sectional components using various methods. Then, it is a three-dimensional modeling method for obtaining the desired shape by laminating them. In general, the name of the 3D printer is widely used. However, internationally, it is often referred to as additive manufacturing technology, or directly translated as additive manufacturing technology. In this specification, the term “3D printer” is mainly used, but expressions are appropriately used according to the intended use.

  The additive manufacturing technology is roughly classified into seven methods as shown in FIG. 2 depending on the type of modeling material and the lamination method.

(1) Vat photopolymerization
(2) Material extrusion method
(3) Powder bed fusion method
(4) Binder Jetting
(5) Sheet lamination method
(6) Material jetting method (Material Jetting)
(7) Directed Energy Deposition (Directed Energy Deposition)
(1) The liquid tank polymerization method was put into practical use at the earliest time among these, and has been used for rapid prototyping under the name of stereolithography before the name of 3D printers became common. . In many cases, an ultraviolet curable (polymerized) resin is used, and an ultraviolet curable resin 41 is held in the tank 3 as shown in FIG. 42 is formed (FIGS. 4A to 4C). The cured region 41 of the first layer is supported by a suitable support member 4. Next, the cured region 41 of the first layer together with the support member 4 is submerged in the liquid (FIG. 4D), or the cured region 41 of the first layer is fixed to a certain depth by raising the liquid level. Just submerge in the liquid. Next, the ultraviolet ray 7 is selectively irradiated again on the liquid surface to form a second layer cured region 42 continuous with the first layer cured region 41 above the first layer cured region 41. (FIG. 4). By repeating this, a three-dimensional model is obtained.

  In recent years, as a 3D printer marketed as a personal use, (2) material extrusion method and (6) material injection method are generally used.

  (2) In many cases, the material extrusion method is a method in which a modeling material made of a thermoplastic resin is heated to be in a melt-flow state and laminated while being extruded from a nozzle (see FIG. 10).

  (6) In the material injection method, the viscosity of the modeling material is often slightly lower than that of the (2) material extrusion method, so to speak, it is a method of modeling while discharging the modeling material instead of the ink of the ink jet printer It is.

  (3) The powder bed fusion bonding method and (4) the binder injection method are characterized by using powdery and granular materials as modeling materials.

  (3) What is the powder bed melt bonding method? As shown in FIG. 11, the modeling material powder 61 is placed in a suitable tank 60. This is often called the material bed 62. As a modeling material, it is a feature that a wide range of modeling materials can be selected as long as it can be melted by an energy ray, such as an inorganic material such as a metal, a resin, or a ceramic. In many cases, the surface of the material floor 62 is selectively irradiated with a laser beam 66 to melt and combine the modeling material powder 61 to form a first modeling layer 67. In FIG. 11, an infrared laser 63 is used as an energy beam source, and the surface of the material bed 82 can be arbitrarily scanned using galvano optical systems 64 and 65. Next, as shown in FIG. 11 (b), after a certain amount of modeling material powder 62 is added, the table 69 is lowered by a certain amount, and the squeegee 68 is moved in the direction of arrow A in the figure to equalize the modeling material content. And flatten. Thus, the material saving 62 is formed again. Next, a laser beam 66 is scanned to form a second modeling layer. By repeating this, a desired three-dimensional model is obtained.

  (4) The binding material injection method uses a material bed made of modeling material powder as in the case of (3) powder bed fusion bonding method, but it has a function of an adhesive that binds the modeling material powder to the material bed. This is a method in which modeling material powders are bound to each other by selectively ejecting a dressing material from an inkjet head or the like.

  (5) As the name suggests, the sheet lamination method is a method of three-dimensional modeling by cutting a sheet-like material such as paper or plastic film into a laminated cross-sectional shape, and sequentially laminating and bonding them.

  The last (7) directional energy deposition method has a typical configuration shown in FIG. 12, and is a method of laminating modeling materials while supplying modeling materials and selectively applying energy simultaneously. The inner nozzle 73 of the double rod nozzle 72 transmits laser light 71 therein, and the laser light 71 is condensed on the surface of the base 75 by a condenser lens 74. From the outer nozzle 76, a shielding gas and modeling material powder (indicated by an arrow 78 in the figure) are sprayed toward the condensing point of the laser beam 71. The sprayed modeling material powder 78 is heated and melted by the laser beam 71 at the condensing point of the laser beam 71, and a molten pool 77 in which the modeling material powder 78 is melted and aggregated is formed on the surface of the base 75. This is a method in which the modeling material is placed and stacked on the base while the relative position of the base 75 and the double rod nozzle 72 is moved and the molten pool 72 is swallowed on the base material. This method is a typical example of a 3D printer using a metal material. From a different point of view, it can be said that this method has been developed as a modeling method by refining and automating the arc welding method that has been known for a long time.

2013 Patent Application Technology Trend Survey Report (Outline) 3D Printer, March 2014, Japan Patent Office Masao Fukushima “Basics of Nonlinear Optimization” Asakura Publishing 2001.20 Gernard A. Holzaphel “Nonlinear Solid Mechanicals: A Continuous Approach for Engineering” Wiley, 2003.23.23.

  The inventors of the present application have previously filed a patent application for an invention related to a three-dimensional modeling method suitable for modeling using a composite material in Japanese Patent Application No. 2006-229964 (pre-publication application, hereinafter referred to as “prior application”). In the specification of the prior application, only the outer shell layer (skin layer) of the three-dimensional model is first modeled with the skin material, and then the inside (core part) of the modeled outer shell layer is modeled with the core material. The featured 3D modeling method is disclosed. In the present specification, the terms “shell layer” and “shell material” are used in place of the terms “skin layer” and “skin material” in the specification of the previous application, but these are substantially the same except for the expression.

  In the prior application, when three-dimensional modeling is performed by additive manufacturing technology, the amount of expensive modeling material used increases as the modeled product increases, and the resulting problem is that the cost of the modeled product increases. As a result, only the outer shell layer (skin layer or shell layer) of a three-dimensional model is modeled by additional manufacturing technology to suppress the amount of expensive modeling material used, and the interior (core part) is modeled by a relatively inexpensive conventional technology. By modeling with materials, the effect of reducing the total modeling cost is obtained.

  However, depending on the material characteristics and mechanical characteristics required for the three-dimensional modeled object, there are cases where the core material is required to have a material as high as or more expensive than the shell material. For example, there is a case where a composite material resin containing expensive carbon fiber, aramid fiber or the like is required as a core material in order to improve mechanical properties such as strength and rigidity. That is, in such a case, there arises a problem of reducing the amount of the core material used as much as possible while satisfying the material characteristics and mechanical characteristics required for the three-dimensional model.

  In order to solve the above-described problems, the present invention is a three-dimensional modeling method, in which a modeling shell having a cavity inside and / or a concave portion on the outer surface is modeled using a first modeling material (shell material). Then, using a second modeling material (core material), a three-dimensional modeling method is provided, in which a three-dimensional modeling object having a desired shape is obtained by filling the cavity and / or the concave portion of the modeling shell. Is done.

  In a preferred aspect of the present invention, there is provided a three-dimensional modeling method characterized in that an envelope surface shape of the modeling shell matches the desired shape.

  In a further preferred aspect of the present invention, there is provided a three-dimensional modeling method characterized in that the shape of the cavity and / or the recess is determined using a structure optimization method.

  In a further preferred aspect of the present invention, there is provided a three-dimensional modeling method characterized in that the modeling shell is modeled by a modeling apparatus using an additional manufacturing technique.

  In a further preferred aspect of the present invention, the core material is cured from a fluid state to a non-fluid state by irradiation of active energy rays or application of thermal energy, and the core material is in the fluid state in the cavity and There is provided a three-dimensional modeling method characterized by filling the recess and / or curing the core material filled in the cavity and / or the recess by irradiation of active energy rays or application of thermal energy. .

  In another aspect of the invention of the present application, the modeling shell is modeled by being divided into a plurality of times in the layered modeling direction of the modeling apparatus according to the additional manufacturing technique, and each modeling of the modeling shell is performed a plurality of times. A three-dimensional modeling method characterized in that the core material is filled in the cavity and / or the concave portion, and after the modeling of all the modeling shells and the filling of the core material is completed, the core material is cured collectively. Provided.

  In another preferred aspect of the present invention, at least one of the shell material and the core material includes a reinforcing material made of carbon fiber, glass fiber, aramid fiber, or a combination thereof. A modeling method is provided.

  In another preferable aspect of the present invention, a three-dimensional modeling apparatus according to any one of the three-dimensional modeling methods is provided.

  The gist of the invention of the present application is to optimize the core part shape to the optimum shape for realizing the characteristics and functions required for the three-dimensional model under various constraints, and to apply the core material to the core part of the optimum shape. The object is to provide a three-dimensional modeling method that achieves the characteristics and functions required for the three-dimensional model by filling and reduces the amount of core material used.

  When the properties and functions required for a 3D object are mechanical properties such as strength and rigidity, the required strength and rigidity are realized under the constraints such as the external shape, size, and dimensions of the 3D object. While calculating the core part shape that minimizes the amount of core material used, i.e., the total internal volume of the core part, using a structure optimization method, and filling the core part into the core part shape, The object is to provide a method of modeling.

  The structure optimization method is a design method and design optimization method widely used in actual design work, as there are many non-patent literature 1 and 2 specialized books, and there are multiple algorithms for the optimization calculation. Various commercial software is also sold as design support and design optimization software.

  Three types of methods are known for structural optimization.

  FIG. 1 conceptually shows the difference between the three methods. As shown in FIG. 1, it is assumed that the amount of bending of a beam when a predetermined load is applied to one end of the cantilever is minimized or within a predetermined critical value under various constraints. This problem is equivalent to the problem of maximizing the rigidity of the beam under the above-mentioned constraints, that is, minimizing (minimizing) compliance.

  At this time, as shown in FIG. 1 (a), the entire structure is defined, constraints such as the volume and weight of the entire beam (ie, the amount of material used) are given, and the dimensions of each part in the entire structure (in the figure) (L1, L2, t1, t2, etc.) are the design parameters, and the design parameter values for minimizing (minimizing) the aforementioned compliance are obtained, that is, optimized, is a dimension optimization method.

  On the other hand, the shape optimization shown in FIG. 1B is called shape optimization, and the overall structure is not defined. Under the same constraints, the optimization is performed using the outer shape (formula representing the outer boundary) as a design parameter. It is a technique to do. In this method, a free curve (curved surface) is often obtained as an optimized outer shape.

  Lastly, FIG. 1C shows a technique called topology optimization, in which a beam is divided into minute elements, and the material density in the minute elements is optimized as a design parameter. The material density is preferably a binary parameter of 1 (the microelements are filled with material) or 0 (the microelements are not filled with material). As shown in FIG. 1 (c), as a result of optimization, the outer shape becomes a free curve as shown in FIG. 1C, and a shape having a cavity inside is also obtained. It is characteristic that it is often obtained.

  Optimization of the core using shape optimization and topology optimization techniques often yields optimization results with free aspects, and the core with such free aspects (having a shell layer) It is particularly preferable to use an additive manufacturing technique, that is, a so-called 3D printer, to perform the modeling.

  ADVANTAGE OF THE INVENTION According to this invention, the effect of reducing the usage-amount of an expensive core material as much as possible can be acquired, satisfy | filling the material characteristic and mechanical characteristic which are requested | required of a three-dimensional molded item.

It is a figure showing each method of structure optimization. It is the schematic of a bending test. It is a perspective view of a test piece. It is a figure of the test piece which has a core part inside. It is a figure of the test piece which has a core part outside. It is a figure which shows the test piece in the middle process of optimization. It is a figure of the mount to which this invention is applied. It is a figure which shows the three-dimensional modeling apparatus by a liquid phase polymerization method. It is a figure which shows the three-dimensional modeling apparatus by a material extrusion method. It is a figure which shows the three-dimensional modeling apparatus by a powder bed fusion | bonding method. It is a principle diagram of the directional energy deposition method. It is a conceptual diagram at the time of applying a composite material to the 3D printer by a material extrusion method by a prior art. It is a conceptual diagram at the time of applying a composite material to the three-dimensional modeling apparatus by a liquid phase polymerization method by a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to FIG.

  An example of optimizing a so-called three-point bending test piece will be described in order to easily explain the modeling method and the modeling procedure using the additive manufacturing technology to which the present invention is applied.

  Three-point bending is a material testing method defined in JIS7171, etc., and as shown in FIG. 2, a load is applied to the center of a test piece 1 on a rectangular parallelepiped supported at both ends by a support 2 with a pressurizer 3. In this test method, the relationship between the load and the amount of deflection is obtained, and the rigidity and strength of the test piece are obtained.

  Consider reinforcing the test piece 1 with a core material which is a composite material. That is, a test piece made of a shell material having a relatively low rigidity is reinforced with a core material having a relatively high rigidity to increase the rigidity of the entire test piece.

  Here, it is assumed that the shape and arrangement of the core material that can keep the amount of deflection under a predetermined load within a predetermined range (critical value) and that minimizes the amount of core material used are obtained. This is equivalent to obtaining a core shape having a minimum core volume that can set the deflection amount at a predetermined load to the critical value. Of course, both the shell material and the core material have known mechanical characteristic values such as Young's modulus and Poisson's ratio.

  First, a method of shaping the outer shape of the test piece with a shell material, arranging a core portion therein, and filling with the core material is conceivable. An example in which the shape of the core portion in this case is optimized using the topology optimization method is shown in FIG. A test piece 5 having a complicated outer shape and having a core portion 4 divided into three is obtained. Note that the outer shape of the test piece 5, that is, the envelope shape, gives a constraint that the original rectangular parallelepiped shape of the test piece 1 shown in FIG. 3 is maintained.

  Optimization is also possible by the method of arranging the core part inside, but in this case the core material needs to be filled into the core part formed inside the shell layer. It is necessary to take measures such as filling or forming a small hole in the shell layer for filling the core material or removing air during filling.

  Therefore, conversely, optimization is also required in which a core material that bears rigidity is placed outside the test piece. This result is shown in FIG. As a derivation process of FIG. 5, first, as shown in FIG. 6, a shape that is appropriately shaped with the core portion 8 as a recess is formed on the entire upper and lower surfaces of the rectangular parallelepiped shape of the original test piece 1. The shape of the core portion 8 provided on the upper and lower surfaces is optimized by a topology optimization method. The result is the test piece 6 shown in FIG. The core portion 7 is divided into three portions as concave portions on both the upper and lower surfaces, and it can be seen that the total volume of the core portion 7, that is, the amount of core material used can be reduced. Even in this optimization, the core portion 7 is provided with a constraint that does not deviate from the original rectangular parallelepiped shape (envelope shape). As described above, the core portion referred to in the present specification can be arranged outside the outer shape of the three-dimensional structure to optimize the shape, and the core portion as a concave portion can be created. In this case, the effect of facilitating filling of the core material is also obtained, which is preferable.

  FIG. 7 shows an example in which the core portion having a more complicated shape is optimized. This is the result of optimizing the shape of the internal core portion by the topology optimization method when modeling the gantry-shaped three-dimensional model 11 as shown in FIG. It has a complex core (b) shape. For modeling of the shell layer having such a core part (b), modeling with a 3D printer is suitable, and the effect of the present invention is exhibited.

DESCRIPTION OF SYMBOLS 1 Test piece 2 Support 3 Pressurizer 4 Core part 5 Test piece 6 Test piece 7 Core part 8 Core part 9 Test piece 10 Core part 11 Base 60 Tank 61 Modeling material powder 62 Material floor 63 Infrared laser 64, 65 Galvano optical system 66 Laser beam 67 First modeling layer 68 Squeegee 69 Table 71 Laser beam 72 Double trap nozzle 73 Inner nozzle 74 Condensing lens 75 Base 76 Outer nozzle 77 Molten pool 90 Reinforcement material 91 Base material 92 Reinforcement material dispersion 93 Tank 94 Sleeping reinforcement

Claims (8)

  A three-dimensional modeling method, in which a first modeling material (shell material) is used to model a modeling shell having a cavity and / or a concave portion on the outer surface, and then a second modeling material (core material) is used. A three-dimensional modeling method characterized by obtaining a three-dimensional molded object having a desired shape by filling the cavity and / or the concave portion of the modeling shell.   2. The three-dimensional modeling method according to claim 1, wherein an envelope surface shape of the modeling shell coincides with the desired shape.   The three-dimensional modeling method according to claim 1, wherein the shape of the cavity and / or the concave portion is determined using a structure optimization method.   The three-dimensional modeling method according to any one of claims 1 to 3, wherein the modeling shell is modeled by a modeling apparatus using an additive manufacturing technique.   The core material is cured from a fluidized state to a non-fluidized state by irradiation with active energy rays or application of thermal energy, and the core material is filled in the cavity and / or the recess in the fluidized state, and thereafter 5. The three-dimensional modeling method according to claim 1, wherein the core material filled in the cavity and / or the concave portion is cured by irradiation with active energy rays or application of thermal energy.   The modeling shell is modeled by being divided into a plurality of times in the layered modeling direction of the modeling apparatus by the additive manufacturing technique, and the core material is formed by the cavity and / or for each modeling of the modeling shell for the plurality of times. 6. The three-dimensional modeling method according to claim 5, wherein the core material is hardened in a lump after filling of the concave portions and completion of modeling of all the modeling shells and filling of the core material.   6. At least one of the shell material and the core material includes a reinforcing material made of any one of carbon fiber, glass fiber, and aramid fiber, or a combination thereof. Solid modeling method.   The three-dimensional modeling apparatus by the three-dimensional modeling method in any one of Claims 1 thru | or 7.

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