Method for manufacturing functionally gradient structure

Abstract

To provide a method for manufacturing a functionally gradient shaped article capable of obtaining desired mechanical characteristics with a single material.SOLUTION: In a method for manufacturing a functionally gradient shaped article, a first partial model including a first region shaped at a first filling factor and a second partial model including a second region shaped at a second filling factor different from the first filling factor and in contact with the first region are produced. A shaping program of a three dimensional printer is created as an entire model including the coupled first partial model and second partial model, and the entire model is shaped using the created shaping program.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a functionally gradient object, and more particularly to a method for manufacturing a functionally gradient object using a three-dimensional printer. [Background technology]

[0002] Conventionally, parts and the like using functionally gradient materials have been developed, in which the composition or properties of the material are gradually changed to give different properties to specific parts. For example, Patent Document 1 discloses a method for producing a three-dimensional object in which the composition is changed by adjusting the mixing ratio of a first liquid composition and a second liquid composition that react when mixed and then injecting the mixture. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-64069 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a three-dimensional object having a functionally gradient function is produced using a three-dimensional printer capable of ejecting the first liquid composition and the second liquid composition from different nozzles. Therefore, producing such a three-dimensional object requires a three-dimensional printer capable of ejecting materials from different nozzles. Furthermore, it is difficult to design the mixing ratio of the compositions to achieve desired properties. For example, it is difficult to adjust mechanical properties such as strength and mass by adjusting the mixing ratio.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a method for manufacturing a functionally gradient object that can obtain desired mechanical properties using a single material. [Means for solving the problem]

[0006] In order to achieve the above object, the manufacturing method of a functionally gradient structure according to the present invention comprises the steps of: Creating a first partial model including a first region formed at a first filling rate, and a second partial model including a second region formed at a second filling rate different from the first filling rate and in contact with the first region; creating a modeling program for a three-dimensional printer as an overall model including the combined first partial model and the second partial model; The entire model is created using the creation program.

[0007] Moreover, the first partial model and the second partial model are In a state in which the first partial model and the second partial model are combined, the first partial model and the second partial model have an overlapping region in which they overlap with each other. This may also be the case.

[0008] Moreover, the first partial model and the second partial model are a reference portion indicating a reference position in a state in which the first partial model and the second partial model are combined; This may also be the case.

[0009] Moreover, the first partial model and the second partial model are having a plurality of the reference portions; This may also be the case.

[0010] Further, the reference portion is Located outside the printing area of ​​the overall model, The first partial model and the second partial model are arranged so that their centroid coordinates coincide with each other. This may also be the case.

[0011] The bottom surface of the reference portion is It coincides with the reference bottom surface which is the bottom surface of the entire model. This may also be the case. [Effects of the Invention]

[0012] According to the method for manufacturing a functionally gradient object of the present invention, it is possible to form a composite of regions with different filling rates using a single material, and therefore it is possible to easily form a functionally gradient object having desired mechanical properties. [Brief explanation of the drawings]

[0013] [Figure 1] 3 is a flowchart showing a flow of a forming process according to the embodiment of the present invention. [Figure 2] FIG. 2 is a conceptual diagram showing an example of a partial model An and an entire model A. [Figure 3] FIG. 1A is a diagram showing a key-fastening component according to Example 1, and FIG. 1B is a diagram showing the configuration of a strength measuring device. [Figure 4] (A) is a diagram of a key fastening part with a uniform filling rate, and (B) is a diagram of a key fastening part made by the divided molding method. [Figure 5] FIG. 10 is a diagram showing the strength measurement results of the key fastening component. [Figure 6] 10(A) is a diagram showing a beam with uniform strength according to Example 2, and FIG. 10(B) is an x-sectional view of FIG. [Figure 7] FIG. 10 is a diagram showing the shape of a theoretically calculated partial model An. [Figure 8] FIG. 10 is a diagram of a beam with uniform strength according to Example 2, shaped for strength measurement. [Figure 9] FIG. 1 is a diagram of a tension-compression testing machine used in a strength test. [Figure 10] 10 is a graph showing the relationship between displacement and load as a result of a strength test according to Example 2. [Figure 11] 10 is a graph showing the withstand load for each test piece as a result of a strength test according to Example 2. [Figure 12] 10A is a diagram showing a beam with uniform strength according to Example 3, and FIG. 10B is a perspective view and a front view of the Sx cross section of FIG. [Figure 13] 12. (A) is a diagram of the uniform strength beam of FIG. 12 rotated with the side surface as the upper surface, and (B) is a perspective view and a front view of the Sx cross section of (A). [Figure 14]10A and 10B are diagrams showing theoretically calculated shapes of a partial model An in the y and z directions. [Figure 15] FIG. 10 is a diagram of a beam with uniform strength according to Example 3, which was shaped for strength measurement. [Figure 16] 10A and 10B are graphs showing the results of a strength test for Example 3, in which (A) is a graph showing the relationship between displacement and load when force is applied to surface A, (B) is a graph showing the relationship between displacement and load when force is applied to surface B, and (C) is a graph showing the specific strength. [Figure 17] (A) is a diagram showing an example of the centroid of a conventional partial model, (B) is a diagram showing an example of the centroid when conventional partial models are combined, (C) is a diagram showing an example of a partial model including a reference part related to variant example 2, and (D) is a diagram showing an example of the centroid when partial models related to variant example 2 are combined. [Figure 18] FIG. 11 is a diagram showing an example of a partial model including a reference part according to Modification 3. DETAILED DESCRIPTION OF THE INVENTION

[0014] Generally, when modeling is performed using a 3D printer, the filling rate and filling shape (shape of the material filled inside the model) of the model to be integrally modeled are set to a single type, and the model is printed with a uniform filling rate and filling shape. In this embodiment, a functionally gradient object is modeled by changing filling conditions such as the filling rate and filling shape for each predetermined region of the integrally modeled object. The 3D printer according to this embodiment is a commonly used, well-known fused deposition modeling method 3D printer.

[0015] Hereinafter, a method for manufacturing a functionally gradient object according to an embodiment of the present invention will be described with reference to the flowchart of FIG.

[0016] First, in the design process, a model to be printed in the usual manner (hereinafter referred to as overall model A) is designed using 3D CAD or the like (Step S1). Next, as shown in FIG. 2, one overall model A is divided into a plurality of partial models A1, A2, . . . , Ak (hereinafter also referred to as partial models An) (Step S2). The number of divisions k of partial model An is not particularly limited as long as it is 2 or more. Specifically, partial model An includes at least partial model A1, which is a first partial model including a first region printed with a first filling rate, and partial model A2, which is a second partial model printed with a second filling rate different from the first filling rate and including a second region adjacent to the first region.

[0017] Next, as a modeling condition setting step, the user creates a modeling program for 3D modeling of the overall model A. Specifically, the user loads the shape data of the partial model An into a slicer (slicing software). A general slicer such as one provided as standard software for the 3D printer to be used may be used. Then, the user sets filling conditions such as the filling rate and filling shape of each partial model An based on the strength, mass, etc. required for each part of the overall model A (step S3).

[0018] Next, the user adjusts the positions of the partial models An and combines them in the slicing software to form the shape of the overall model A (step S4). As shown in Figure 2, the partial models An are arranged on the printing surface (print bed) of the 3D printer so that their divided surfaces come into contact with each other. This makes it possible to create an overall model A consisting of multiple regions with different filling rates, filling shapes, etc.

[0019] The user uses the functions of the slicing software to create a modeling program (modeling tool path data) for the entire model A created in step S4 (step S5).

[0020] Subsequently, in the modeling process, the user inputs the modeling program created in step S5 into a three-dimensional printer to model the whole model A (step S6). Through the above procedure, a functionally gradient object is modeled.

[0021] Example 1 In this example, a keyed fastening part that is a functionally gradient object in which the filling rate is changed between the periphery of the key groove and the other portion will be described.

[0022] As shown in Figure 3(A), the key fastening component of this example has a hole with a key groove in the center to allow key fastening. The hole diameter is 22 mm, and the key width is 8 mm. The key fastening component has mounting holes on the left and right sides to allow a lever to be attached for applying torque. Since accurate torsional rigidity cannot be determined if the hole is deformed, a metal cylindrical member is inserted into the lever mounting hole. As shown in Figure 3(B), the lever has a hook for hanging a weight, and a 5 kg weight was hung from the hook to apply torque to the key fastening component. The displacement of the lever caused by applying torque was measured, and the torsional rigidity of the key fastening component was calculated.

[0023] In this example, strength measurements were performed when the key fastening component was molded with a filling rate of 55% (case 1, FIG. 4(A)) and when it was molded with a filling rate of 100% (case 2). As an example of the molding method according to the present invention (hereinafter also referred to as the divided molding method), strength measurements were performed when the part was molded by dividing the part around the central hole including the key groove and the other parts (case 3, FIG. 4(B)). In the divided molding method, the filling rate was 100% for the part around the central hole and 37% for the other parts.

[0024] The strength measurement results of the above three key fastening components are shown in Table 1 and Figure 5 below. [Table 1]

[0025] As shown in Table 1 and Figure 5, between case 1 and case 2, case 2, which has a higher filling rate, has a higher torsional rigidity. Furthermore, case 3 is able to achieve a torsional rigidity equal to or greater than that of case 2. Therefore, it can be seen that the segmented manufacturing method according to the present invention makes it possible to reduce the amount of manufacturing material used and to manufacture lightweight, high-strength functionally gradient objects.

[0026] Example 2 In this example, we will explain the case where a beam with uniform strength is created by changing the moment of inertia. A beam with uniform strength is a beam in which the magnitude of the maximum stress acting on all cross sections along the axis is equal. As shown in Figures 6(A) and 6(B), the beam in this example is composed of partial models A1 and A2 with the same shape and high filling rate, which are placed above and below, and a partial model A3 with a low filling rate, which is placed between partial models A1 and A2.

[0027] The beam in this example has a height H of 10 mm, a width (depth) B of 7 mm, and a length L of 50 mm. The filling rate of partial models A1 and A2 is 100%, the filling rate of partial model A3 is 5%, and the filling rate of the cross section of the base of the beam is set to 100%. The setting values ​​for each partial model A1 to A3 are as shown in Table 2 below. [Table 2]

[0028] The relationship between the distance x from the tip of the beam and the height Kx of the cross section of the partial models A1 and A2 with a filling rate of 100% is expressed by the following formula (1).

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[0029] The shapes shown by solid lines in Figure 7 are the shapes of partial models A1 and A2 calculated using equation (1). As shown in Figure 7, the boundary surface between partial models A1 and A2 and partial model A3 derived from the calculation results is a curved surface. In this example, to facilitate modeling using a 3D printer, the boundary surface between partial models A1 and A2 and partial model A3 was modeled as a flat surface, as shown by dotted lines in Figure 7. Furthermore, in this example, to facilitate strength verification, the above-mentioned beams designed as cantilevers were connected in a symmetrical shape to form a beam with the shape shown in Figure 8.

[0030] As shown in Figure 9, the test specimen, the beam shown in Figure 8, was placed on two supports of a tension-compression testing machine, and a force was applied in the vertical direction (z-axis direction) to the center of the test specimen. The magnitude of the applied force and the displacement of the center of the test specimen in the z-axis direction were then measured. In this example, a beam (case 4) manufactured with a uniform filling rate of 100%, a uniform strength beam (case 5) which is the functionally graded object described above, and a beam (case 6) manufactured with a uniform filling rate of 38% were manufactured and their strengths were compared.

[0031] The masses of the test pieces for cases 4 to 6 are as shown in Table 3 below. [Table 3]

[0032] The strength measurement results for the above three beams are shown in Figures 10 and 11. As shown in Figures 10 and 11, when the change in force with respect to displacement is evaluated as rigidity, it can be seen that the rigidity of the uniform strength beam in Case 5 is almost equivalent to that of the solid beam in Case 4. It can also be seen that the mass of the uniform strength beam in Case 5 is approximately the same as that of the low-filling-ratio beam in Case 6, where the rigidity is significantly reduced. Therefore, it can be seen that the uniform strength beam, which is a functionally graded structure according to the present invention, is lightweight yet has high strength.

[0033] Example 3 This example describes the case where a beam with uniform strength was produced that was made up of partial models An with a different shape from that of Example 2. As shown in Fig. 12(A), the beam in this example was made up of high-filling-ratio partial models A1 and A2 of the same shape arranged above and below, high-filling-ratio partial models A3 and A4 of the same shape arranged on the left and right, and low-filling-ratio partial models A5 and A6 arranged between the partial models A1 to A4.

[0034] 12(A) and (B), x is the distance from the fulcrum, L is the distance from the fulcrum to the midpoint o of the beam, H is the height of the cross section of the beam, B is the width of the cross section of the beam, k is the width of the high-filling-ratio part which are the partial models A1 to A4, d is the height of the high-filling-ratio part, w is the shell height of the low-filling-ratio part which are the partial models A5 and A6, and t is the shell width.

[0035] The second moment of area of ​​the high filling ratio region consisting of partial models A1 to A4 is I hy , the second moment of area of ​​the low filling ratio region consisting of partial models A5 and A6 is I ly The second moment of area I with respect to the y-axis at the cross section Sx, which is the yz cross section at a distance x from the fulcrum sxy I sxy =I hy +I ly As a result, the following equation (2) is obtained.

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[0036] When the values ​​of the height d and width k of the high filling ratio portion satisfy equation (2), the dimension setting of the high filling ratio portion can be obtained such that the maximum stress on each cross section of the beam is the same when stress is applied to the top surface of the beam (surface A in Figure 12(A)).

[0037] Figures 13(A) and (B) show the case where force N is applied to the side of the beam (surface B in Figure 13(A)). As in the case where force is applied to the top surface (surface A) described above, the moment of inertia I with respect to the Z axis is sxz is expressed as the following equation (3).

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[0038] The parameters relating to the beams in this example are as shown in the table below. The filling rate of the partial models A1 to A4 was set to 100%, and the filling rate of the partial models A5 and A6 was set to 5%. [Table 4]

[0039] Figure 14 shows the change curves of width k and height d with respect to distance x calculated based on equations (2) and (3). Because the beam is symmetrical, only the change curve from the midpoint o of the beam to the fulcrum is shown. As shown in Figure 14, the boundary surface between the high and low fill rate areas derived from the calculation results is a curved surface. In this example, to facilitate modeling using a 3D printer, the boundary surface between the high and low fill rate areas is made flat, as shown by the dotted line in Figure 14.

[0040] As in Example 2, a test specimen, a beam as shown in Figure 15, was placed on two supports of a tension-compression testing machine, and a force was applied in the vertical direction (z-axis direction) to the center of the test specimen. The magnitude of the applied force and the displacement of the center of the test specimen in the z-axis direction were then measured. In this example, measurements were performed on both the A-plane direction and the B-plane direction of the beam. Furthermore, in this example, a beam (case 7) manufactured with a uniform filling rate of 100%, a uniform strength beam (case 8) which is the functionally graded object described above, and a beam (case 9) manufactured with a uniform filling rate of 42% were manufactured, and their strengths were compared.

[0041] The masses of the test specimens for cases 7 to 9 are as shown in Table 5 below. [Table 5]

[0042] The strength measurement results for the above three beams are shown in Figures 16(A) to 16(C). As shown in Figures 16(A) to 16(C), when evaluating the change in force with respect to displacement as rigidity, it can be seen that the rigidity of the uniform strength beam in case 8 is almost equivalent to that of the solid beam in case 7 on both sides A and B. It can also be seen that the mass of the uniform strength beam in case 7 is approximately the same as that of the low-filling-ratio beam in case 9, where the rigidity is significantly reduced. Therefore, it can be seen that the uniform strength beam, which is a functionally gradient structure according to the present invention, is lightweight yet has high strength on both the top and side surfaces.

[0043] As described above, according to the manufacturing method of the present invention for a functionally gradient object, it is possible to combine a variety of filling shapes and filling rates using a single material, and therefore it is possible to easily manufacture a functionally gradient object having desired mechanical properties.

[0044] (Variation 1) In the above embodiment, the partial models An are arranged to contact each other to form the overall model A, but this is not limited to this. When the partial models An, for example, the first partial model A1 and the second partial model A2, are combined, the partial models A1 and A2 may have overlapping regions where they overlap each other. This reduces the risk of gaps occurring at the contact surfaces between the partial models An when the overall model A is created by arranging the partial models An. In this case, the size of the overlapping regions between the partial models An may be set based on the printing conditions. For example, when the size of the overlapping region is set based on the nozzle diameter of a three-dimensional printer, the distance between the contact surfaces of the partial models An may be set to approximately 1 to 5% of the nozzle diameter. Furthermore, the partial models An do not need to have overlapping regions in all contacting portions.

[0045] (Variation 2) Furthermore, each partial model An may include a reference portion indicating a reference position at which the partial model An is to be placed for combination. Generally, in slicing software, each partial model An is placed by specifying the centroid position of each partial model An shown in FIG. 17(A) using coordinates on the printing surface (FIG. 17(B)). However, if the shape of the partial model An is complex, it is difficult to grasp the position of the centroid relative to the overall model A, and therefore, placing the partial model An requires time and effort. In this example, as shown in FIG. 17(C), each partial model An is created to include multiple reference portions P outside the printing area of ​​the overall model A. In this case, the reference portions P are created to be located outside the printing area of ​​the overall model A in the +x direction, +y direction, -x direction, and -y direction, respectively. Furthermore, the centroid coordinates of each partial model An, determined by the multiple reference portions P of each partial model An, are determined by a predetermined reference point (g A ) As a result, by arranging each partial model An so that the coordinates of its centroid coincide with the reference point, the partial models An can be easily arranged and connected to form the overall model A (FIG. 17(D)).

[0046] (Variation 3) If a partial model An does not include the bottom surface of the overall model A, when the partial model An is combined as part of the overall model A, it will be placed in a floating position. However, when placing a partial model An in slicing software, each partial model An cannot be placed in the air and must be placed so that it is in contact with the printing surface. In this example, as shown in FIG. 18, the reference portion P of each partial model An is configured so that its bottom surface coincides with the reference bottom surface, which is the bottom surface of the overall model A. As a result, even if the original partial model An was separated from the overall model A as a floating area in the air, the bottom surface of the reference portion P included in the partial model An is configured to coincide with the reference bottom surface, making it possible to place the partial model An on the printing surface. Therefore, the partial models An can be easily placed and combined to form the overall model A. [Industrial Applicability]

[0047] The present invention is suitable for fabricating a functionally gradient object using a three-dimensional printer, and is particularly suitable for fabricating a functionally gradient object that achieves desired mechanical properties using a single material. [Explanation of symbols]

[0048] A is the overall model, An is the partial model, P is the reference part

Claims

1. creating a first partial model including a first region formed at a first filling rate, and a second partial model including a second region formed at a second filling rate different from the first filling rate and in contact with the first region; creating a modeling program for a three-dimensional printer as an overall model including the combined first partial model and the second partial model; forming the overall model using the modeling program; A method for manufacturing a functionally gradient object, comprising:

2. The first partial model and the second partial model are In a state in which the first partial model and the second partial model are combined, the first partial model and the second partial model have an overlapping region in which they overlap with each other. The method for manufacturing a functionally gradient object according to claim 1 .

3. The first partial model and the second partial model are a reference portion indicating a reference position in a state in which the first partial model and the second partial model are combined; The method for manufacturing a functionally gradient object according to claim 1 .

4. The first partial model and the second partial model are having a plurality of the reference portions; The method for manufacturing a functionally gradient object according to claim 3 .

5. The reference portion is Located outside the printing area of ​​the overall model, The first partial model and the second partial model are arranged so that their centroid coordinates coincide with each other. The method for manufacturing a functionally gradient object according to claim 4 .

6. The bottom surface of the reference portion is It coincides with the reference bottom surface which is the bottom surface of the entire model. The method for manufacturing a functionally gradient object according to claim 3 .

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