Additive manufacturing apparatus and method

Abstract

To form a molded object by appropriately addressing a thinned portion that occurs in the molded object, thereby obtaining a product that conforms to the designed dimensions.SOLUTION: An additive manufacturing device includes: forming means 11 for forming a molded object 1 containing layers by sequentially laminating layers 3 to be formed by irradiating a material N with laser light L to melt and solidify the material, based on a design model that conforms to the design dimensions; measuring means 12 for measuring a surface shape and a forming thickness of the molded object from a surface of the molded object during the forming process by the forming means; thinning detection means 13 that detects a thinned portion in the molded object based on measurement data from the measurement means; and control means 14 that controls the forming means to perform molding corresponding to the thinned portion when the thinned portion is detected in the molded object by the thinning detection means.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to an additive manufacturing apparatus and an additive manufacturing method. [Background technology]

[0002] For example, additive manufacturing (AM) using the powder bed method involves spreading material powder on a table and using laser light with high focusing properties to produce fine, highly accurate and complex shapes compared to castings, etc., and in recent years it has been increasingly used not only for prototyping but also in a wide range of fields such as aviation and medicine. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5905060 [Patent Document 2] Patent Publication No. 2021-85662 [Patent Document 3] JP 2019-73766 A Summary of the Invention [Problem to be solved by the invention]

[0004] Additive manufacturing using metal materials is affected by the output and driving accuracy of the laser oscillator installed in the device, the type of metal material used, and also by the shape of the object, so the versatility of construction conditions is low, and defects occur inside the molten metal, which require repair. For example, Public Document 1 proposes a method of detecting internal defects by measurement using elastic waves during manufacturing, removing the detected defective parts by machining, and measuring the model after backfilling the removed parts.

[0005] However, even if internal defects are detected and removed, there are cases where the shape (design dimensions) of the design model cannot be reproduced after printing due to thinning or shape abnormalities caused by thermal deformation during printing, etc., which poses the time-consuming challenge of having to review the design model and reprint it.

[0006] The embodiments of the present invention have been made in consideration of the above-mentioned circumstances, and aim to provide an additive manufacturing device and method that can produce a product that fits the design dimensions by manufacturing an object in a way that appropriately responds to thinning areas that occur in the object. [Means for solving the problem]

[0007] An additive manufacturing apparatus in an embodiment of the present invention is characterized in that it is configured with a manufacturing means that irradiates a material with an energy beam to melt and solidify the material, sequentially stacking layers to form a molded object including the layers, based on a design model that conforms to design dimensions, a measuring means that measures the surface shape and molding thickness of the object from the surface of the object during molding by the molding means, a thinning detection means that detects a thinning portion that has occurred in the object from measurement data by the measuring means, and a control means that, when the thinning portion of the object is detected by the thinning detection means, controls molding by the molding means in response to the thinning portion.

[0008] An additive manufacturing method in an embodiment of the present invention is characterized in that it includes the steps of: a modeling means irradiating a material with an energy beam to melt and solidify the material, sequentially stacking layers to form a model including the layers, based on a design model that conforms to design dimensions; a measurement means measuring the surface shape and modeling thickness of the object from the surface of the object during modeling by the modeling means; a wall-thinning detection means detecting a wall-thinning portion that has occurred in the object from measurement data by the measurement means; and, when the wall-thinning detection means detects the wall-thinning portion in the object, a control means controlling modeling by the modeling means in accordance with the wall-thinning portion. Effect of the Invention

[0009] According to an embodiment of the present invention, a product that meets the design dimensions can be obtained by manufacturing a shaped object in a way that appropriately addresses a thinning portion that occurs in the shaped object. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a configuration of an additive manufacturing apparatus according to an embodiment. [Diagram 2] FIG. 2 is a schematic side view showing a camera as a surface shape measuring device and a laser ultrasonic measuring device as a model thickness measuring device in the measuring means of FIG. 1, together with a model. [Diagram 3] FIG. 3 is a schematic side view showing the camera and the laser ultrasonic measurement device in FIG. 2 together with a molded object in which a thinning portion has occurred. [Figure 4] 4 is a graph showing an example of a measurement result obtained by the laser ultrasonic measurement device in FIG. 2 and FIG. 3. [Diagram 5] 5 is a graph illustrating the state of determining whether or not there is a thinning portion based on the measurement results in FIG. 4, in which (A) shows a case where there is no thinning portion, and (B) shows a case where there is thinning portion. [Figure 6] FIG. 4 is a schematic side view of a molded object showing an example in which the thinned portion in FIG. 3 is repaired by forming a reinforcement portion through re-molding. [Figure 7] 7 is a flowchart showing a procedure for forming a shaped object, including the formation of the excess reinforcement portion in FIG. 6. [Figure 8] FIG. 4 illustrates the reconstruction of the design model in response to the occurrence of the thinning portion in FIG. 3, where (A) is a schematic side view showing the original design model and the molded object, and (B) is a schematic side view showing the reconstructed design model and the product obtained by machining the molded object. [Figure 9] 9 is a flowchart showing a procedure for forming an object when the design model in FIG. 8 is reconstructed. [Figure 10] FIG. 2 is a schematic side view showing an eddy current flaw detection measuring device as a model thickness measuring device, together with a model. [Figure 11] FIG. 2 is a block diagram showing the configuration of an additive manufacturing apparatus including a modified embodiment of the modeling means in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of an additive manufacturing apparatus according to an embodiment. When a thinned portion 2 (Fig. 3) occurs in an object 1 (Fig. 2) due to thermal deformation during a modeling process of additive manufacturing (AM modeling), the additive manufacturing apparatus 10 shown in Fig. 1 appropriately deals with the thinned portion 2, and includes a modeling means 11, a measuring means 12, a thinned portion detection means 13, and a control means 14.

[0012] The modeling means 11 sequentially stacks layers 3 formed by irradiating, for example, a powdered material N with laser light L as energy rays to melt and solidify it, and models a model 1 including these layers 3 based on a design model 4 (FIGS. 3 and 8(A)) that conforms to design dimensions. The modeling means 11 is of a laser deposition type and is configured with a nozzle device 15, a material supply device 16, an optical device 17, and a moving device 18, and the material supply device 16, the optical device 17, and the moving device 18 are controlled by a control means 14.

[0013] The material supplying device 16 supplies a predetermined amount of the stored material N to the nozzle device 15. Here, the material N is, for example, a powdered metal material or a resin material. The optical device 17 generates a laser beam and emits it to the nozzle device 15. The moving device 18 moves the base 20 via a stage 19 in three mutually perpendicular axial directions. The nozzle device 15 supplies the material N from the material supplying device 16 onto the base 20, and also focuses and irradiates the supplied material N with laser beam L. As a result, the material N is melted and solidified on the base 20 to form a layer 3, and the layers 3 are sequentially stacked to form a shaped object 1 including the layer 3.

[0014] The measuring means 12 has a surface shape measuring device 21 and a modeling thickness measuring device 22 shown in Fig. 2. The surface shape measuring device 21 measures the shape (e.g., uneven shape) of the surface 1A (3A) of the object 1 (layer 3) from the surface 1A (3A) during modeling of the object 1 (layer 3) by the modeling means 11. The surface shape measuring device 21 is two or more cameras 23, a laser sensor, etc., and measures the shape of the surface 1A (3A) of the object 1 (layer 3) by, for example, triangulation. When unevenness is present on the surface 1A (3A) of the object 1 (layer 3) measured by the surface shape measuring device 21, the modeling thickness (described later) of the object 1 (layer 3) measured by the modeling thickness measuring device 22 is corrected based on the shape of the surface 1A (3A).

[0015] The object thickness measuring device 22 continuously measures the object thickness of the object 1 (layer 3) from the surface 1A (3A) of the object 1 (layer 3) along the surface 1A (3A) during the object 1 (layer 3) being formed by the modeling means 11, and is, for example, a laser ultrasonic measuring device 24. The laser ultrasonic measuring device 24 irradiates laser light and measures the object thickness of the object 1 (layer 3) from the received waves.

[0016] Specifically, the laser ultrasonic measurement device 24 irradiates the surface 1A (3A) of the object 1 (layer 3) with the laser light La for transmission waves and the laser light Lb for reception waves, and measures the thickness of the object 1 (layer 3) from the received wave of the reflected laser light Lb for reception waves. That is, the waveform of the received wave is periodically repeated as shown in Fig. 4, and the period Δt of this repeated waveform depends on the thickness of the object 1 (layer 3), so the thickness of the object 1 (layer 3) is measured based on the period Δt. The laser ultrasonic measurement device 24 continuously measures the thickness of the object 1 (layer 3) by continuously irradiating the laser light La for transmission waves and the laser light Lb for reception waves along the surface 1A (3A) of the object 1 (layer 3).

[0017] The wall-thinning detection means 13 shown in Fig. 1 detects wall-thinning parts 2 (Fig. 3) that have occurred due to thermal deformation or the like during the molding of the object 1 (layer 3) from measurement data of a laser ultrasonic measurement device 24, which is an object thickness measurement device 22. That is, the wall-thinning detection means 13 first models the molding thickness based on the measurement data of the molding thickness of the object 1 (layer 3) continuously measured by the laser ultrasonic measurement device 24, and obtains a molding model. Next, the wall-thinning detection means 13 detects wall-thinning parts 2 that have occurred in the object 1 (layer 3) by comparing the thickness data of this molding model with the design model.

[0018] Specifically, as shown in Fig. 5, for a design model 4 in which no thinning portion 2 exists, the waveform of the measurement data measured by the laser ultrasonic measurement device 24 is assumed to have a period Δt0 (Fig. 5(A)). Also, for a molding model of the object 1 (layer 3) actually molded by the molding means 11, the waveform of the measurement data measured by the laser ultrasonic measurement device 24 is assumed to have a period Δt1 (Fig. 5(B)). At this time, the thinning detection means 13 compares the period Δt0 with the period Δt1 to calculate the difference, and if Δt1<Δt0, determines that the thinning portion 2 has occurred in the object 1 (layer 3) that was actually molded.

[0019] 2 and 3, the object thickness measuring device 22 is the laser ultrasonic measuring device 24, but it may be an eddy current flaw measuring device 25 as shown in Fig. 10. That is, this eddy current flaw measuring device 25 has an eddy current flaw detector 26 mounted on a scanning axis unit 27, and uses this scanning axis unit 27 to cause the eddy current flaw detector 26 to scan along the surface 1A (3A) of the object 1 (layer 3), thereby continuously measuring the object thickness of the object 1 (layer 3).

[0020] As described above, the control means 14 shown in FIG. 1 controls the material supply device 16, the optical device 17 and the moving device 18 to form an object 1 (layer 3) on the base 20 using the material N and laser light L from the nozzle device 15. When a thin-walled portion 2 is detected in the object 1 (layer 3) by the thin-walled detection means 13, the control means 14 controls the formation of the above-mentioned object 1 (layer 3) using the following two control patterns in accordance with the detected thin-walled portion 2.

[0021] In the first pattern, as shown in Figures 3 and 6, when the thinning detection means 13 detects a thinning portion 2 in the object 1 (layer 3), the control means 14 controls the shaping means 11 (nozzle device 15, material supply device 16, optical device 17, and moving device 18) to perform re-shaping by re-melting the area of ​​the thinning portion 2 to form an excess portion 28.

[0022] 7, in the first control pattern, the control means 14 controls the material supplying device 16, the optical device 17, and the moving device 18 based on the pre-stored design model 4 to eject the material N from the nozzle device 15 and irradiate the laser light L, thereby forming the layer 3 of the model 1 in a predetermined area of ​​the base 20 (S11). Next, the control means 14 controls the surface shape measuring device 21 (e.g., the camera 23) of the measuring means 12 to measure the surface 3A of the layer 3, and controls the modeling thickness measuring device 22 (e.g., the laser ultrasonic measuring device 24) to measure the modeling thickness of the layer 3 (S12).

[0023] Next, the control means 14 detects whether or not a thin portion 2 has occurred in the shaped layer 3 based on the measurement data in step S12 (S13). When the control means 14 detects the thin portion 2 in the shaped layer 3 in step S13, the control means 14 controls the shaping means 11 to perform re-shaping to remelt the area of ​​the thin portion 2 and form the excess portion 28 (S14).

[0024] After re-modeling in step S14, or when no thinning portion 2 is detected in the layer 3 in step S13, the control means 14 judges whether or not all layers 3 have been formed based on the design model 4 (S15), and ends the process if all layers have been formed. If it is determined in step S15 that all layers 3 have not been formed, the control means 14 sequentially executes steps S11 to S15 to form new layers 3 on the layers 3 that have already been formed, thereby modeling the object 1.

[0025] In the above-mentioned first control pattern, every time a thinned portion 2 is detected in layer 3 of the object 1, re-modeling is performed to form an excess portion 28 in the range of this thinned portion 2, and then a new layer 3 is formed on the layer 3 on which this excess portion 28 was formed. Then, when all layers 3 have been modeled, the excess portion 28 is removed by machining (cutting) so as to fit the design model 4 (design dimensions). In this way, modeling proceeds while allowing the occurrence of thinned portions 2 in layer 3 of the object 1, so that the modeling time required to complete the object 1 can be shortened.

[0026] In the second control pattern, as shown in Fig. 8(A), when the thinning portion 2 is detected in the object 1 (layer 3) by the thinning detection means 13, the control means 14 temporarily stops the modeling and discards the object 1 that has been modeled up to that point, and further, as shown in Fig. 8(B), the control means 14 corrects and reconstructs the design nozzle 4 taking into account the thinning portion 2 so that the design dimensions are achieved by machining after the completion of modeling of the object 1, and causes the modeling means 11 (nozzle device 15, material supply device 16, optical device 17, and moving device 18) to perform modeling again based on this reconstructed design model (reconstructed design model 5). When the thinning portion 2 occurs in the object 1 (layer 3) modeled based on the reconstructed design model 5, the area 6 (hatched area in Fig. 8(B)) including the thinning portion 2 is removed by machining after the completion of modeling of the object 1, so that the object 1 becomes a product 7 that satisfies the original design model 4 (design dimensions).

[0027] That is, in this second control pattern, as shown in Fig. 9, the control means 14 controls the material supplying device 16, the optical device 17, and the moving device 18 based on the pre-stored design model 4 (Fig. 8(A)), to eject the material N from the nozzle device 15 and irradiate the laser light L, thereby forming the layer 3 of the model 1 in a predetermined area of ​​the base 20 (S21). Next, the control means 14 controls the surface shape measuring device 21 (e.g., the camera 23) of the measuring means 12 to measure the surface 3A of the layer 3, and controls the modeling thickness measuring device 22 (e.g., the laser ultrasonic measuring device 24) to measure the modeling thickness of the layer 3 (S22).

[0028] Next, the control means 14 detects whether or not a reduced-wall portion 2 has occurred in the modeled layer 3 based on the measurement data in step S22 (S23). When no reduced-wall portion 2 is detected in the layer 3 in step S23, the control means 14 determines whether or not all layers 3 have been formed based on the design model 4 (S24), and ends modeling when all layers 3 have been formed.

[0029] When a reduced-wall portion 2 is detected in the layer 3 formed in step S23, the control means 14 temporarily terminates the forming, and discards the layer 3 (modeled object 1) formed up to that point (S25). Then, the control means 14 corrects and reconstructs the design model 4 taking into consideration the reduced-wall portion 2 so that the designed dimensions are achieved by machining after the completion of forming, and causes the forming means 11 to form the modeled object 1 (layer 3) again based on this reconstructed design model 5 (FIG. 8(B)), and executes steps S21 to S25.

[0030] If it is determined in step S24 that all layers 3 have not been formed, the control means 14 sequentially executes steps S21 to S25. In this case, when a thinned portion 2 occurring in another location is detected in step S23, the control means 14 temporarily ends the modeling, discards the layer 3 (modeled object 1) that has been modeled up to that point, constructs a new reconstructed design model 5 again, and causes the modeling means 11 to model the layer 3 (modeled object 1) using this new reconstructed design model 5.

[0031] In the second control pattern described above, modeling is temporarily terminated when a thin portion 2 is detected in layer 3 of the object 1. Then, a reconstructed design model 5 is constructed by modifying the original design model 4 (FIG. 8(A)) so that the design dimensions are achieved by removing the area 6 (FIG. 8(B)) including the thin portion 2 through machining after modeling is completed, and modeling of the object 1 (layer 3) is reconstructed by the modeling means 11 based on this reconstructed design model 5. For this reason, it is possible to obtain a product 7 that satisfies the design dimensions by the reconstructed modeling described above and machining of the object 1 after modeling is completed.

[0032] As configured as above, this embodiment provides the following advantages. During modeling by the modeling means 11 (nozzle device 15, material supply device 16, optical device 17, moving device 18), when the thinning detection means 13 detects a thinned portion 2 that has occurred in the modeled object 1 (layer 3) from the measurement data of the surface shape and modeling thickness of the modeled object 1 (layer 3) measured by the measurement means 12 (surface shape measurement device 21, modeling thickness measurement device 22), the control means 14 controls the modeling means 11 to execute modeling of the first or second control pattern corresponding to this thinned portion 2. As a result, a product 7 that matches the design dimensions can be obtained by modeling by the modeling means 11 and machining (cutting) after modeling.

[0033] In the above description of the layered modeling apparatus 10, the modeling means 11 is of the laser deposition type, but the modeling means 31 may be of the powder bed type as shown in Fig. 11. This modeling means 31 includes a material supply storage area 32 and a squeegee 33 instead of the material supply device 16, and a nozzle device 34 irradiates only laser light L without spraying material N. Also, instead of the moving device 18, stage 19, and base 20, a modeling area 36 includes a base plate 35 that can be raised and lowered by a drive system 35M. The squeegee 33 scrapes out the material N pushed up by a lift plate 37 raised by a drive system 37M in the material supply storage area 32 toward the base plate 35.

[0034] In the modeling area 36, ​​a plurality of layers 3 are stacked to form the model 1. In the modeling of the model 1, the control means 14 controls the drive system 35M to lower the base plate 35 by the thickness of one layer 3, and controls the drive system 37M to raise the lift plate 37 to lift the material N in the material supply storage area 32. Next, the control means 14 moves the squeegee 33 toward the base plate 35 to scrape the material N on the lift plate 37 toward the base plate 35, and deposits the material N on the stacked layers 3 in the modeling area 36. Thereafter, the control means 14 controls the optical device 17 to irradiate the laser light L from the nozzle device 34 onto the stacked material N to form a new layer 3. The modeling means 31 repeats the above-mentioned operation to stack the layers 3 to form the model 1. The layered modeling device 10 may have the above-mentioned powder bed type modeling means 31.

[0035] Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, substitutions, changes, and combinations can be made without departing from the gist of the invention, and these substitutions, changes, and combinations are included in the scope and gist of the invention, as well as in the scope of the invention and its equivalents described in the claims.

[0036] For example, as shown in Fig. 3, it has been confirmed that thinning portion 2 caused by thermal deformation during molding is likely to occur in a range where the overbank angle θ is small. For this reason, the measurement of the molding thickness by the molding thickness measuring device 22 (laser ultrasonic measuring device 24, eddy current flaw measuring device 25) does not necessarily need to be performed over the entire range of the molded object 1 (layer 3), but may be performed only in a range where the overbank angle θ is small. This makes it possible to shorten the time required to detect thinning portion 2 by the measuring means 12 and thinning detection means 13, the time required for re-molding to form excess portion 28, and the time required to modify design model 4 and construct reconstructed design model 5. [Explanation of symbols]

[0037] Reference Signs List 1... object, 1A... surface, 2... thinning portion, 3... layer, 3A... surface, 4... design model, 5... reconstructed design model, 10... additive manufacturing device, 11... molding means, 12... measuring means, 13... thinning detection means, 14... control means, 21... surface shape measuring device, 22... molding thickness measuring device, 23... camera, 24... laser ultrasonic measuring device, 28... excess portion, L... laser light (energy beam), N... material

Claims

1. a modeling means for sequentially laminating layers formed by irradiating a material with an energy beam to melt and solidify the material, and modeling a structure including the layers based on a design model that conforms to design dimensions; a measuring means for measuring a surface shape and a modeling thickness of the object from a surface of the object during modeling by the modeling means; a wall-thinning detection means for detecting a wall-thinning portion generated in the object from measurement data obtained by the measurement means; and a control means for controlling modeling by the modeling means in response to the thinning portion when the thinning portion is detected in the modeled object by the thinning detection means.

2. The additive manufacturing apparatus according to claim 1, characterized in that the wall-thinning detection means is configured to detect a wall-thinning portion that has occurred in the object by modeling the molding thickness of the object based on measurement data obtained by the measurement means to obtain a molding model, and comparing thickness data between this molding model and a design model.

3. The additive manufacturing device according to claim 1 or 2, wherein the control means controls the manufacturing means to perform re-modeling by re-melting the area of ​​the reduced metal part to form an excess part when the reduced metal part is detected in the molded object by the reduced metal part detection means.

4. 3. The additive manufacturing device according to claim 1 or 2, wherein when the thinning detection means detects a thinning portion in the object, the control means modifies and reconstructs the design model taking into account the thinning portion so that the object will have designed dimensions through post-modeling processing, and controls the modeling means to perform modeling based on this reconstructed design model.

5. The layered manufacturing apparatus according to claim 1 , wherein the measuring means includes a surface shape measuring device that measures a surface shape of the object from the surface of the object.

6. The additive manufacturing apparatus according to claim 1 , wherein the measuring means includes an object thickness measuring device that measures the object thickness from a surface of the object.

7. 7. The additive manufacturing apparatus according to claim 6, wherein the object thickness measuring device is a laser ultrasonic measuring device that irradiates laser light and measures the object thickness from a received wave.

8. The additive manufacturing apparatus according to claim 6, wherein the object thickness measuring device is an eddy current flaw detector that measures the object thickness by scanning an eddy current flaw detector over a surface of the object.

9. a step in which a modeling means irradiates a material with an energy beam to melt and solidify the material, sequentially stacking layers to form a model, and modeling an object including the layers based on a design model that conforms to design dimensions; a measuring means for measuring a surface shape and a modeling thickness of the object from a surface of the object during modeling by the modeling means; a step in which a wall-thinning detection means detects a wall-thinning portion occurring in the object from measurement data obtained by the measurement means; and when the thinning detection means detects a thinning portion in the object, a control means controls the molding by the molding means in response to the thinning portion.

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