Manufacturing method of the object

Abstract

To provide a manufacturing method of a molded object, which can inspect presence or absence of an internal defect in the molded object without CT scanning.SOLUTION: There is provided a manufacturing method of a molded object, which comprises a lamination manufacturing step. In the lamination manufacturing step, a modeled object is modeled by laminating a single-layer structure body formed by moving a head while discharging a strand of resin in a fluid state from the head, and inspection of the molded object is performed based on data obtained during the modeling.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a shaped object.

[0002] Patent Document 1 discloses a method for forming a three-dimensional network structure object by laminating single-layer structures formed by scanning strands of molten resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-146988 Summary of the Invention [Problem to be solved by the invention]

[0004] In the method of Patent Document 1, the thickness of the strands may fluctuate during modeling, resulting in defects such as areas where the linear resin constituting the three-dimensional mesh structure inside the model is too thin or too thick. The occurrence of such defects leads to variations in the quality of the model.

[0005] It is possible to use CT scans to check for defects inside a molded object, but this has the problem of high implementation costs and low inspection efficiency.

[0006] The present invention has been made in view of the above circumstances, and provides a method for manufacturing a molded object that enables inspection of the presence or absence of internal defects in a molded object without using a CT scan. [Means for solving the problem]

[0007] According to the present invention, there is provided a method for manufacturing a molded object, which includes an additive manufacturing process, in which a molded object is manufactured by stacking single-layer structures formed by ejecting strands of resin in a fluid state from a head while moving the head, and inspecting the molded object based on data obtained during the manufacturing process.

[0008] In the method of the present invention, the object is inspected based on data obtained during the manufacturing process, making it possible to inspect the object for internal defects without using a CT scan.

[0009] Various embodiments of the present invention will be described below as examples, and the embodiments shown below can be combined with each other. Preferably, in the method described above, the data includes a weight of the object at a point in time during the fabrication. Preferably, the method described above, wherein the data includes thickness of the strands during the build. Preferably, in the method described above, the inspection is performed during the modeling, and if the result of the inspection is a failure, the modeling is stopped. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view showing an additive manufacturing process. [Figure 2] FIG. 2A is a perspective view showing a three-dimensional mesh structure 2, and FIG. 2B is a perspective view showing a single layer structure. [Figure 3] 10 is a graph showing the relationship between the printing time from the start of printing to the completion of printing and the weight reference value. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an independent invention.

[0012] 1. First embodiment A method for manufacturing a shaped object according to an embodiment of the present invention will now be described. This method includes an additive manufacturing process.

[0013] As shown in Figure 1, in the additive manufacturing process, a single-layer structure 7 is formed by ejecting strands 5 of fluid resin from a head 6 while moving the head 6, and then stacking these single-layer structures 7 to form a model 10.

[0014] Examples of the sculpted object 10 include breast bodies such as bra pads and artificial breasts, those used in the nursing field (such as supporters to prevent bedsores, supporters to prevent clubfoot, and children's splints), and sports applications (such as shoe insoles).

[0015] The resin constituting the strands 5 is not particularly limited, and examples thereof include ABS, polyolefin (for example, polypropylene), polyester, and thermoplastic elastomer.

[0016] The strand 5 is linear and has a diameter of, for example, 0.5 to 6.0 mm, preferably 1.0 to 4.0 mm. Specific examples of the diameter include 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0017] The head 6 is configured to melt the resin supplied to the head 6 and extrude the strand 5. The form of the resin supplied to the head 6 is not limited, and may be a filament or pellets. When the resin is in the form of a filament, a gear built into the head 6 is engaged with the filament, and the gear is rotated to move the filament downstream, thereby extruding the molten strand 5 from the head 6. When the resin is in the form of pellets, a screw-type extruder having a built-in screw can be used as the head 6, and the molten strand 5 can be extruded from the head 6 by rotating the screw. When the resin is very flexible, such as a thermoplastic elastomer, it may be difficult to move the filament downstream by rotating the gear, so in this case, the head 6 is preferably a screw-type extruder.

[0018] The strand 5 is discharged onto the building surface 8. The head 6 and the building surface 8 are configured to be capable of relative movement in three dimensions (i.e., in the X, Y, and Z directions). The single-layer structure 7 can be formed by moving the head 6 and the building surface 8 relative to each other within the plane while discharging the strand 5 from the head 6. The relative movement within the plane is preferably achieved, for example, by moving the head 6 within the plane while the building surface 8 remains stationary, but the building surface 8 may also move. The strand 5 is in a fluid state when discharged, and is cooled and solidified after discharge.

[0019] After forming the first monolayer structure 7, the head 6 and the printing surface 8 are moved relative to each other in the height direction so that the distance between them is increased by one pitch, and then the second monolayer structure 7 is formed on the first monolayer structure 7. By repeating this process of forming the next monolayer structure 7 on the lower monolayer structure 7, a molded object 1 is obtained in which monolayer structures 7 are stacked one upon another. The relative movement in the height direction may be performed by raising the head 6 by one pitch or by lowering the printing surface 8 by one pitch. The ratio of the height of one pitch to the diameter of the strand 5 is, for example, 0.3 to 1.0, preferably 0.4 to 0.9. Specific examples of this ratio include 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1.0, and may be within a range between any two of the values ​​exemplified here. The height of one pitch may be constant or may vary during molding.

[0020] The thus-formed object 10 has a three-dimensional network structure 2, as shown in Fig. 2A. The three-dimensional network structure 2 is a network-like structure formed by stacking single-layer structures 7 made of linear resin 2a formed by solidifying strands 5. When the object 10 has such a structure, the rigidity of the object 10 can be changed by changing the spacing between adjacent linear resin pieces 2a or by changing the thickness of the linear resin pieces 2a.

[0021] The diameter of the linear resin 2a is, for example, 0.5 to 6.0 mm, preferably 1.0 to 4.0 mm, and specifically, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0022] In one example, the three-dimensional network structure 2 is formed by repeatedly stacking single-layer structures 11, 12, and 13 shown in FIG. 2B in this order. The single-layer structure 11 has linear resin 11a composed of a plurality of parallel lines spaced apart from one another. The single-layer structure 12 has linear resin 12a composed of a plurality of parallel lines spaced apart from one another. The single-layer structure 13 has linear resin 13a composed of a plurality of parallel lines spaced apart from one another. The linear resins 11a, 12a, and 13a are arranged to extend in directions offset by 60 degrees from one another.

[0023] The resin discharge speed from the head 6 is easily affected by external environmental factors such as temperature and humidity, and the state of resin supply to the head 6. When the resin discharge speed decreases or increases, the strands 5 discharged from the head 6 become thinner or thicker, resulting in defects such as excessively thin or thick linear resin 2a constituting the three-dimensional network structure 2 inside the model 10. The occurrence of such defects leads to variations in the quality of the model 10.

[0024] After the formation of the object 10 is completed, it is not possible to determine whether a defect exists inside the object 10 by inspecting the appearance or measuring the weight of the object 10. In order to determine whether a defect exists inside the object 10, it is necessary to use a CT scan, but the introduction cost of the CT scan is high and the inspection efficiency is low.

[0025] In this embodiment, under such circumstances, the object 10 is inspected based on data obtained during the manufacturing process, making it possible to inspect the object 10 for internal defects without using a CT scan.

[0026] In this embodiment, this data is the weight of the molded object 10 at a point in time during molding. In this case, by comparing the measured weight of the molded object 10 at a point in time during molding with the reference weight value at that point in time, it can be determined whether molding has been performed appropriately up to that point in time. The comparison can be performed, for example, based on whether the difference between the measured value and the reference value is within an acceptable range, or whether the ratio of the measured value to the reference value is within an acceptable range. The reference value is, for example, the weight when molding has been performed appropriately. If the measured value is close to the reference value, it can be inferred that the amount of resin discharged up to that point in time was appropriate, and it can be determined that no defects exist in the part formed up to that point in time.

[0027] Data acquisition may be performed at only one point during modeling and inspection may be performed based on that data. However, in this case, if there are periods in which resin is excessively dispensed and periods in which resin is insufficiently dispensed up to the time of measurement, the excess and insufficiency may cancel each other out, resulting in a determination that the amount of resin dispensed was appropriate. Therefore, to improve inspection accuracy, data acquisition is preferably performed at multiple points during modeling or continuously. The shorter the interval between data acquisitions, the higher the inspection accuracy. This interval is preferably, for example, 100 minutes or less, more preferably 10 minutes or less, and even more preferably 1 minute or less. This interval may be, for example, 0 to 100 minutes, specifically, 0, 0.001, 0.01, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 50, or 100 minutes, and may be within a range between or less than any two of the values ​​exemplified here.

[0028] FIG. 3 is a graph showing the relationship between the printing time from the start of printing to the completion of printing and the weight reference value. This graph shows the reference value of the increase in weight of the printed object. From this graph, it can be seen that the weight reference values ​​at printing times t1 to t4 are rw1 to rw4, respectively. Note that, for convenience, an example is given here in which data is acquired at four time points, but as mentioned above, the shorter the interval between data acquisitions, the better.

[0029] During actual modeling, the weight of the object 10 during modeling is measured at modeling times t1 to t4, and the measured values ​​are mw1 to mw4. In this case, by comparing the measured value with a reference value for each of the modeling times t1 to t4, it is possible to determine whether modeling has been performed properly up to that point. For example, for the modeling time t1, the measured value mw1 is compared with the reference value rw1 to inspect the object 10 (pass / fail judgment) for the modeling up to that point. If the inspection passes, similar inspections are performed for the modeling times t2, t3, and t4. If pass judgment results are obtained at all of the time points, the object 10 can be determined to be a pass product (properly modeled). On the other hand, if the inspection at any of the modeling times t1 to t4 fails, the object 10 can be determined to be a fail product. This method makes it possible to determine whether a defect exists inside the object 10 without using a CT scan.

[0030] This inspection may be performed after the completion of the modeling of the object 10, or may be performed during the modeling of the object 10. When the inspection is performed during the modeling of the object 10, if the inspection result is unacceptable, the modeling can be stopped. For example, if the inspection result at modeling time t1 is unacceptable, the modeling can be stopped at that point. In this case, the remaining modeling is not performed, thereby saving time and materials. Furthermore, when the inspection is performed during modeling, there is no need to perform the inspection after modeling, so the inspection process after modeling can be omitted.

[0031] The printing surface 8 is preferably the measurement surface of the weighing scale 14. In this case, the weight of the object 10 being printed can be measured in real time without moving it. The weighing scale 14 may store the acquired data in a built-in memory, or may store the data in an external memory via wired or wireless communication. Inspection based on the acquired data may be performed by the weighing scale 14 itself, or by an external computer.

[0032] 2. Second embodiment This embodiment is similar to the first embodiment, and the main difference is the data acquired during modeling. The following mainly describes the differences.

[0033] In this embodiment, the data acquired during modeling is the thickness of the strands 5 during modeling. The thickness of the strands 5 increases or decreases depending on the amount of resin discharged from the head 6, so by checking whether the thickness of the strands 5 during modeling is appropriate, it is possible to determine whether a defective portion exists inside the model 10.

[0034] The explanation of data acquisition and inspection is the same as in the first embodiment, and the ideal value of the thickness of the strand 5 may be used as the reference value.

[0035] The thickness of the strand 5 can be obtained, for example, by image analysis of an image including the strand 5. Such an image can be obtained using an imaging element such as a CCD or CMOS. In one example, the imaging element is preferably attached to the head 6. In this case, since the imaging element moves together with the head 6, an image including the strand 5 can be obtained immediately after the strand 5 is discharged from the head 6.

[0036] 3. Other embodiments The data acquired during the modeling process may include both the weight of the model 10 during modeling and the thickness of the strands 5 during modeling, and may also include other data acquired during modeling that is useful for inspecting the modeling state. Then, it may be determined whether the modeling state during modeling is appropriate based on a comprehensive evaluation of the acquired data. [Explanation of symbols]

[0037] 1: Modeled object 2: Three-dimensional mesh structure 2a: Linear resin 5: Strand 6: Head 7: Single layer structure 8: Modeling surface 10: Modeled object 11: Single layer structure 11a: Linear resin 12: Single layer structure 12a: Linear resin 13: Single layer structure 13a: Linear resin 14: Weight scale

Claims

1. A method for manufacturing a shaped object, comprising: Equipped with an additive manufacturing process, In the additive manufacturing process, a single-layer structure is formed by discharging a strand of a fluidized resin from a head while moving the head, and then the single-layer structure is laminated to manufacture a shaped object; inspecting the object based on data obtained during the modeling of the object; the data includes a weight of the object at a point in time during the modeling; The inspection is performed by comparing the weight measurement with a reference weight value at the time to determine whether the build has been performed properly up to that point in time; The method, wherein the reference value is the weight of the shape if it were properly formed.

2. 10. The method of claim 1, The inspection is performed during the fabrication, If the result of the inspection is unsuccessful, the build is stopped.

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