JP2018127651A - Lamination forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lamination forming method capable of satisfactorily removing residual powder remaining in a path formed inside a formed object.SOLUTION: Three-dimensional data for forming an object 50 is acquired (S10). Prior to actually forming an object 50, removability of a residual powder in a path 60 after formation of the object 50 using the three-dimensional data is determined based on the roughness of the internal surface of the path (S20). On the basis of the removability determined in the S20 process, the three-dimensional data acquired in the process of S10 is corrected (S30). Using the three-dimensional data corrected in the S30 process, the object 50 is formed by lamination forming (S40).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an additive manufacturing method, and more particularly, to an additive manufacturing method for manufacturing a formed object by repeating powder lamination and fusion bonding.

  In recent years, a layered manufacturing apparatus that produces a three-dimensional layered object by irradiating a powder made of an inorganic material or an organic material with a light beam, and sintering or melting and solidifying has attracted attention. Specifically, a process of forming a powder layer by spreading powder on a surface plate, and a process of forming a hardened layer by irradiating a predetermined region of the powder layer with a light beam and sintering or melting and solidifying it. And repeat. Thus, a three-dimensional shaped object can be manufactured by laminating and integrating a large number of hardened layers.

  When using a modeled object as, for example, a molding die, a path through which a fluid can flow is formed in the modeled object in order to provide functions such as cooling and heating. Patent document 1 discloses the manufacturing method of a photomolding thing. In the method according to Patent Document 1, when a powder layer is irradiated with a light beam to form a bonded layer, unbonded powder is continuously formed by leaving the powder unbonded without partially irradiating the light beam. A fluid path is formed in the powder binder. Then, uncompressed powder in the fluid path is removed by blowing or sucking compressed air from one of the plurality of openings in the fluid path that opens to the surface of the powder combined body.

JP 2003-225948 A

  In the method according to the cited document 1, the fluidity of air for removing the residual powder may be deteriorated in a portion where the inner wall surface is rough in the fluid path. Therefore, in the method according to the cited document 1, there is a possibility that unbonded residual powder cannot be removed satisfactorily.

  The present invention provides an additive manufacturing method capable of satisfactorily removing residual powder remaining in a path formed inside a molded article.

According to the present invention, when manufacturing a three-dimensional shaped object by repeating the lamination and fusion bonding of the powder, the powder remains partially unbonded so that the powder is not partially melt-bonded. It is a layered manufacturing method for manufacturing the modeled object in which a hollow path through which a first fluid is circulated is formed by allowing powder to remain, and obtaining three-dimensional data related to the modeled object, Before manufacturing the modeled object based on the roughness of the inner wall surface of the path in the path model simulating the path using three-dimensional data, after the modeled object is manufactured using the three-dimensional data Using the step of determining the removability of the residual powder of the path, the step of correcting the three-dimensional data so as to improve the determined removability, and using the corrected three-dimensional data, Layered manufacturing method and a step of producing a serial shaped object is provided. According to the above method, it is comprised so that the three-dimensional data concerning a modeling thing may be corrected so that it may become the arrangement | positioning of a path | route which the removability of residual powder is improved. Therefore, the additive manufacturing method according to the present invention can satisfactorily remove the residual powder remaining in the path formed inside the modeled article.
Preferably, in the step of determining the removability, it is determined that the removability is better as the laminated thickness of the inner wall surface of the path is thinner. According to the above method, determination of the appropriate removability according to the lamination thickness of the inner wall surface of the path is realized.
Preferably, in the step of determining the removability, the removability is determined to be poorer as the inner wall surface of the route is downward. According to the above method, determination of appropriate removability according to the direction of the inner wall surface of the route is realized.
Preferably, in the step of determining the removability, the removability is better as the lamination thickness of the inner wall surface of the path is thinner, and the removability is determined to be worse as the inner wall surface of the path is downward. In the step of determining the removability, the orientation of the inner wall surface of the path affects the quality of the removability rather than the laminated thickness of the inner wall surface of the path than the laminated thickness of the inner wall surface of the path. The removability is determined by preferentially considering the direction of the inner wall surface of the route. According to the above method, the removability can be determined based on the weight of the influence on the removability.
Preferably, the location of the route that is the target of the removability determination is determined according to the shape of the route. According to the above method, since the determination is made only for the portion where the removability is estimated to be not good, the removability can be determined efficiently.

  According to the invention of the present application, it is possible to satisfactorily remove residual powder remaining in a path formed inside a molded article.

1 is a schematic cross-sectional view showing an overview of an additive manufacturing apparatus according to a first embodiment. 1 is a block diagram illustrating a configuration of a control device according to a first embodiment; 3 is a flowchart illustrating an additive manufacturing method according to the first exemplary embodiment. It is a figure which illustrates the modeling thing manufactured with the additive manufacturing method concerning Embodiment 1. FIG. 3 is a partially enlarged view of a modeled object according to Embodiment 1. FIG. It is a flowchart which shows the detail of the process of S20 in the flowchart shown in FIG. It is a figure for demonstrating the pressure loss in a path | route. It is an enlarged view of the inner wall surface of a path | route. It is a table | surface which shows the correction coefficient according to lamination | stacking thickness. It is a cross-sectional view of a path. It is a cross-sectional schematic diagram of a path | route. It is a table | surface which shows the correction coefficient according to the direction of the inner wall face of a path | route. It is a table | surface which shows the correction coefficient in the case of considering simultaneously lamination | stacking thickness and the direction of the inner wall face of a path | route.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

(Embodiment 1)
First, the layered manufacturing apparatus according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an overview of an additive manufacturing apparatus 1 according to the first embodiment. As shown in FIG. 1, the layered manufacturing apparatus 1 according to the first embodiment includes a base 30, a surface plate 2, a modeling tank 3, a modeling tank support unit 4, a modeling tank drive unit 5, a column 6, a support unit 7, and a laser. A scanner 8, an optical fiber 9, a laser oscillator 10, a squeegee 11, a basket 12, a powder distributor 13, a powder supply unit 14, and a control device 100 are provided.

  The base 30 is a table for fixing the surface plate 2 and the column 6. The base 30 is installed on the floor so that the upper surface on which the surface plate 2 is placed is horizontal. The surface plate 2 is placed and fixed on the horizontal upper surface of the base 30. The upper surface of the surface plate 2 is also horizontal, and powder is spread on the upper surface of the surface plate 2, and a three-dimensional shaped object 50 is formed. In the example of FIG. 1, the surface plate 2 is a quadrangular columnar member. As shown in FIG. 1, a flange-like convex portion 2 a that protrudes in the horizontal direction is formed on the entire periphery of the upper surface of the surface plate 2. Since the outer peripheral surface of the convex portion 2 a is in contact with the inner surface of the modeling tank 3 throughout, the laminated powder 51 can be held in the space surrounded by the upper surface of the surface plate 2 and the inner surface of the modeling tank 3. it can. Here, the holding force of the laminated powder 51 can be increased by providing a seal member (not shown) made of felt, for example, on the outer peripheral surface of the convex portion 2 a that is in contact with the inner surface of the modeling tank 3.

  The modeling tank 3 is a cylindrical member that holds the powder spread on the upper surface of the surface plate 2 from the side surface. In the example of FIG. 1, since the surface plate 2 has a quadrangular prism shape, the modeling tank 3 is a square pipe having a flange portion 3a at the upper end. The modeling tank 3 is made of, for example, a stainless steel plate having a thickness of about 1 to 6 mm (preferably about 3 to 5 mm) and is lightweight. A powder layer is formed on the upper opening end 3b of the modeling tank 3, and a hardened layer is formed by irradiating the powder layer with a laser beam LB. The shape of the upper opening end 3b is, for example, 600 mm × 600 mm.

  The modeling tank 3 is installed so as to be movable in the vertical direction (z-axis direction). Then, each time a hardened layer is formed, the modeling tank 3 is raised by a certain amount with respect to the surface plate 2 to form a modeled object 50. Here, in the additive manufacturing apparatus 1 according to the first embodiment, only the constant-weight and lightweight modeling tank 3 may be raised. Therefore, the powder layer can be formed with high accuracy every time. As a result, the molded article 50 can be formed with high accuracy.

  The modeling tank support part 4 is a support member that supports the lower surface of the flange part 3a at three points so that the upper surface of the flange part 3a of the modeling tank 3 is horizontal. The modeling tank support part 4 is connected to a connecting part 5c of a modeling tank drive unit 5 that moves the modeling tank 3 in the vertical direction (z-axis direction).

  The modeling tank drive unit 5 is a drive mechanism for moving the modeling tank 3 in the vertical direction (z-axis direction). The modeling tank driving unit 5 includes a motor 5a, a ball screw 5b, and a connecting portion 5c. When the motor 5a is driven, the ball screw 5b extending in the z-axis direction rotates. When the ball screw 5b rotates, the connecting portion 5c moves in the vertical direction (z-axis direction) along the ball screw 5b. Since the modeling tank support part 4 which supports the modeling tank 3 is connected with the connection part 5c as above-mentioned, the modeling tank 3 becomes movable by the modeling tank drive part 5 to an up-down direction (z-axis direction). The driving source of the modeling tank driving unit 5 is not limited to a motor, and a hydraulic cylinder or the like may be used.

  Here, the modeling tank driving unit 5 is fixed to the upper part of the support column 6 erected substantially vertically (that is, in the vertical direction) from the base 30. As described above, in the additive manufacturing apparatus 1 according to the present embodiment, the modeling tank driving unit 5 is installed outside the modeling tank 3, so that it is excellent in maintainability.

  The laser scanner 8 irradiates the powder layer formed on the upper opening end 3 b of the modeling tank 3 with the laser beam LB. The laser scanner 8 has a lens and a mirror (not shown). Therefore, as shown in FIG. 1, the laser scanner 8 can focus the laser beam LB on the powder layer regardless of the position on the horizontal plane (xy plane) in the powder layer. Here, the laser beam LB is generated in the laser oscillator 10 and introduced into the laser scanner 8 via the optical fiber 9.

  The laser scanner 8 is fixed to the flange portion 3 a of the modeling tank 3 through the support portion 7. Therefore, the distance between the laser scanner 8 and the powder layer that is the irradiation target of the laser beam LB can be kept constant. Therefore, the layered manufacturing apparatus 1 according to the first embodiment can manufacture the modeled object 50 with high accuracy.

  The squeegee 11 includes a first squeegee 11a and a second squeegee 11b. Both the first squeegee 11a and the second squeegee 11b extend in the y-axis direction. Further, the squeegee 11 can slide in the x-axis direction from the one flange portion 3 a to the opposite flange portion 3 a via the upper opening end 3 b of the modeling tank 3.

  As shown in FIG. 1, the powder is supplied between the first squeegee 11a and the second squeegee 11b on the flange 3a on the negative side of the x-axis. Here, the powder for forming the powder layer for 2 times is supplied. That is, the squeegee 11 slides from the x-axis minus side flange portion 3 a to the x-axis plus side flange portion 3 a, so that one powder layer is formed at the upper opening end 3 b of the modeling tank 3. As indicated by a broken line in FIG. 1, while the powder layer is irradiated with the laser beam LB and the hardened layer is formed, the squeegee 11 stands by on the flange 3a on the x-axis plus side. Then, the squeegee 11 slides from the x-axis plus side flange portion 3 a to the x-axis minus side flange portion 3 a, whereby another powder layer is formed on the upper opening end 3 b of the modeling tank 3.

  For example, when the formation region of the hardened layer is narrow, the hardened layer formation region is covered without sliding the squeegee 11 from the x-axis minus side flange portion 3a to the x-axis plus side flange portion 3a as much as possible. Above, you may stop the slide in the middle. The amount of powder for forming the powder layer can be saved and the time can be shortened.

  The basket 12 and the powder distributor 13 are for uniformly distributing the powder dropped from the powder supply unit 14 in the longitudinal direction of the squeegee 11. An opening having a length (y-axis direction) that is narrower than the distance (x-axis direction) between the first squeegee 11 a and the second squeegee 11 b (x-axis direction) and is approximately the same as the powder injection region of the squeegee 11 is formed on the lower surface of the flange 12. Is formed.

  The powder distributor 13 is a plate-like member having the same shape as the cross-sectional shape of the groove of the ridge 12. The powder distributor 13 can be slid in the y-axis direction by a drive mechanism (not shown). Here, in FIG. 1, the powder distributor 13 is drawn away from the basket 12 for easy understanding. However, in practice, the powder distributor 13 slides in contact with both sides of the groove of the ridge 12 without any gap. The powder distributor 13 is slid from one end to the other end where the powder is dropped in the reed 12 so that the powder is uniformly distributed in the longitudinal direction (y-axis direction) of the squeegee 11 through the opening of the reed 12. The

  For example, when the formation area of the hardened layer is narrow, the powder distributor 13 is not slid from one end to the other end of the basket 12 as much as possible. May be. The amount of powder for forming the powder layer can be saved and the time can be shortened.

  The powder supply unit 14 is a small tank in which powder is stored. Details of the powder supply unit 14 will be described later. The powder is made of an inorganic material (metal or ceramic) or an organic material (plastic). Preferably, iron powder having an average particle size of about 20 μm is used.

  As described above, the additive manufacturing apparatus 1 manufactures the three-dimensional object 50 by repeating powder lamination and fusion bonding. In addition, a hollow path through which a fluid for performing a predetermined function is circulated is formed inside the modeled object 50 according to the first embodiment. The additive manufacturing apparatus 1 prevents the powder from being partially melt-bonded and leaves the powder unbonded in the portion, thereby forming a hollow path.

  The control device 100 controls the operation of the additive manufacturing apparatus 1. Specifically, the control device 100 is connected to the modeling tank driving unit 5, the laser scanner 8, the laser oscillator 10, the squeegee 11, and the like by wire or wirelessly. The control device 100 stores three-dimensional data for manufacturing the modeled object 50. The control apparatus 100 controls these components using this three-dimensional data. Thereby, the layered manufacturing apparatus 1 forms the modeled object 50.

  FIG. 2 is a block diagram of a configuration of the control device 100 according to the first embodiment. The control device 100 is a computer, for example. The control device 100 includes a CPU (Central Processing Unit) 102, a ROM (Read Only Memory) 104, a RAM (Random Access Memory) 106, and an interface unit 108 (IF; Interface) as main hardware configurations. . The CPU 102, ROM 104, RAM 106, and interface unit 108 are connected to each other via a data bus or the like.

  The CPU 102 has a function as an arithmetic device that performs control processing, arithmetic processing, and the like. The ROM 104 has a function for storing a control program and an arithmetic program executed by the CPU 102. The RAM 106 has a function for temporarily storing processing data and the like. The interface unit 108 inputs / outputs signals to / from the outside via wired or wireless. The interface unit 108 may include a communication port.

  In addition, the control device 100 includes a three-dimensional data acquisition unit 112, an internal structure review unit 114, a three-dimensional data correction unit 116, and an additive manufacturing control unit 118. The three-dimensional data acquisition unit 112, the internal structure review unit 114, the three-dimensional data correction unit 116, and the additive manufacturing control unit 118 can be realized, for example, when the CPU 102 executes a program stored in the ROM 104. In addition, the necessary program is recorded in an arbitrary non-volatile recording medium and installed as necessary, so that the three-dimensional data acquisition unit 112, the internal structure review unit 114, the three-dimensional data correction unit 116, and the additive manufacturing control are performed. The unit 118 may be realized.

  In addition, the program can be stored using various types of non-transitory computer readable media and supplied to a computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media are magnetic recording media (eg flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg magneto-optical disks), CD-ROM, CD-R, CD-R / W. Semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  Note that the three-dimensional data acquisition unit 112, the internal structure review unit 114, the three-dimensional data correction unit 116, and the additive manufacturing control unit 118 are not limited to being realized by software as described above, and may be hardware such as some circuit elements. It may be realized by wear. Furthermore, the three-dimensional data acquisition unit 112, the internal structure review unit 114, the three-dimensional data correction unit 116, and the additive manufacturing control unit 118 do not need to be physically provided in one apparatus, but as separate hardware. It may be configured. In that case, each of the three-dimensional data acquisition unit 112, the internal structure examination unit 114, the three-dimensional data correction unit 116, and the additive manufacturing control unit 118 may function as a computer.

  Further, the processing performed by the internal structure review unit 114 need not be performed by a device such as a computer, but may be performed by the operator himself. Further, the control device 100 may not be integrated with the additive manufacturing apparatus 1, and may not be a dedicated device of the additive manufacturing apparatus 1. The control device 100 may be a general-purpose information terminal.

  FIG. 3 is a flowchart illustrating the additive manufacturing method according to the first embodiment. Note that the additive manufacturing method according to the first embodiment may be performed using, for example, a prototype manufactured based on three-dimensional data, or may be performed by computer simulation using CAE (Computer Aided Engineering). Good.

<Three-dimensional data acquisition unit 112>
The three-dimensional data acquisition unit 112 acquires three-dimensional data for modeling the modeled object 50 (step S10). Specifically, the three-dimensional data acquisition unit 112 generates three-dimensional data (3D data) using CAD / CAM (Computer Aided Design / Computer Aided Manufacturing) data. Thereby, the three-dimensional data acquisition unit 112 acquires three-dimensional data. Note that the three-dimensional data acquisition unit 112 may acquire the three-dimensional data by receiving the three-dimensional data generated by another device.

  FIG. 4 is a diagram illustrating a modeled object 50 manufactured by the additive manufacturing method according to the first embodiment. FIG. 4 is a cross-sectional view of the modeled object 50. The model 50 illustrated in FIG. 4 can be manufactured using the three-dimensional data acquired by the three-dimensional data acquisition unit 112. The modeled object 50 according to the first embodiment is, for example, a mold. And the molded article 50 concerning Embodiment 1 has the hollow path | route 60 which distribute | circulates a fluid inside. That is, the three-dimensional data can be generated so as to include information on the path 60 inside the shaped article 50 and exclude a structure (a melt-bonded powder layer) in a portion corresponding to the path 60.

  The channel 60 circulates a fluid for achieving a predetermined function. For example, the path 60 may circulate a fluid that cools a mold part formed on the model 50. Further, for example, the path 60 may circulate a fluid for heating or insulating the shaped object 50. Further, for example, the path 60 may circulate a fluid for soundproofing or vibration isolation. Specifically, the amplitude and phase of the wave propagating through the model 50 may be changed by the fluid flowing through the path 60. Further, for example, the path 60 may be an air shooter that circulates a gas that conveys an object.

  In the following description, it is assumed that the modeled object 50 is a mold, and the path 60 circulates a fluid (first fluid) for cooling the mold. That is, the modeled object 50 according to the first embodiment is a mold having a cooling circuit. The model 50 may be simply a cooling circuit, or a mold may be connected to the model 50. Further, although the path 60 illustrated in FIG. 4 has a relatively simple shape for the description of the embodiment, the actual path may have a complicated shape having a large number of bent portions, branches, and the like. .

  The fluid flowing through the path 60 is, for example, cooling water. The fluid flows into the path 60 from the inlet 60a of the path 60, and the fluid flows out from the outlet 60b. In FIG. 4, the left side is the upstream side and the right side is the downstream side. Moreover, the area | region enclosed with the broken line located in the upper side of the molded article 50 in FIG. 4 is the high temperature area | region 92 and the high temperature area | region 94 which require cooling. The high temperature region 92 is upstream of the high temperature region 94. The path 60 is disposed so as to approach the high temperature region 92 and the high temperature region 94.

  Specifically, a partial path 62 extending in the horizontal direction is arranged on the downstream side of the partial path 61 extending upward (in the vertical direction) from the inlet 60 a so as to approach the high temperature region 92. Further, in order to cool the cooling water heated by the high temperature region 92, a partial path 63 extending downward on the downstream side of the partial path 62 and a downstream side of the partial path 63 so as to be away from the high temperature area. A partial path 64 extending in the horizontal direction is arranged. Also, a partial path 65 extending upward on the downstream side of the partial path 64 and a partial path 66 extending in the horizontal direction on the downstream side of the partial path 65 are arranged so as to approach the high temperature region 94. Yes. And the partial path | route 67 extended below toward the exit 60b is arrange | positioned in the downstream of the partial path | route 66. FIG. Therefore, the bent portion 71 and the bent portion 72 are formed on both sides of the partial path 62, the bent portion 73 and the bent portion 74 are formed on both sides of the partial path 64, and the bent portion 75 and the bent portion 76 are formed on both sides of the partial path 66. Is formed.

  FIG. 5 is a partially enlarged view of the modeled object 50 according to the first embodiment. FIG. 5 is a cross-sectional view of the modeled object 50 on a plane cut substantially perpendicular to the flow direction of the fluid flowing through a portion (for example, the partial path 62) extending in the horizontal direction in the path 60. As described above, the additive manufacturing apparatus 1 prevents the powder from being melt-bonded at a position corresponding to the path 60. Specifically, in the powder layer 52A below the path 60, the powder is entirely irradiated with the laser beam LB, and the powder is melt-bonded. On the other hand, in the powder layers 52 </ b> B to 52 </ b> K, which are the upper layers, the powder is not melt-bonded by partially irradiating the laser beam LB, and the powder remains in the path 60. In the powder layer 52L above the path 60, the powder is totally melt-bonded. Thus, the path | route 60 is formed because the part in which the powder is not melt-bonded is continuously formed by the powder layers 52B to 52K. In addition, in the upper layer of the path 60 (for example, the powder layers 52H to 52L), the stacking pitch may be changed so that the melt-bonded powder does not fall due to gravity. In this case, the upper surface (ceiling) of the horizontal path 60 can be rough.

  In addition, as described above, after the model 50 is manufactured, residual powder that remains without being melt-bonded exists in the path 60. Therefore, it is necessary to remove this residual powder. In the first embodiment, a residual powder remaining in the path 60 by injecting fluid such as compressed air, water, or oil from the inlet 60a into the path 60, or sucking air in the path 60 from the outlet 60b, for example. Remove. That is, in Embodiment 1, the residual powder remaining in the path 60 is removed using the fluid (second fluid).

<Internal structure review section 114>
Next, the internal structure examining unit 114 examines the internal structure of the modeled object 50 (step S20). Specifically, the internal structure reviewing unit 114 uses the path model simulating the path 60 using the three-dimensional data before actually manufacturing the modeled object 50 to use the internal structure (path 60) of the modeled object 50. Determines whether or not the predetermined performance is satisfied. The “route model” may be a prototype manufactured (prototype) using the three-dimensional data acquired in step S10. Further, the “route model” may be a route reproduced by simulation in the CAE analysis using the three-dimensional data acquired in the step S10.

  There are various “predetermined performance” to be examined. In the first embodiment, the internal structure examining unit 114 examines “function establishment”, “structure establishment”, and “residual powder removal”. “Function establishment” indicates whether or not the function to be exhibited by the first fluid (cooling function in the present embodiment) can be sufficiently exhibited. “Structure establishment” indicates whether or not the molded article 50 can ensure the required rigidity even when the molded article 50 has a hollow path 60 therein. “Removability of residual powder” indicates whether or not the residual powder existing in the path 60 of the shaped article 50 can be sufficiently removed. Here, in the additive manufacturing method according to the first embodiment, at least “removability of residual powder” is studied. Therefore, in the present embodiment, it is not always necessary to examine “function establishment” and “structure establishment”.

  That is, in the layered manufacturing method according to the first embodiment, at least each location in the path 60 (partial paths 61 to 67 and the bent portion 71 without being melt-bonded after the model 50 is manufactured using the three-dimensional data. ˜76 etc.) and the removability of the residual powder remaining is determined. Furthermore, in other words, in the process of S20, the internal structure reviewing unit 114, before actually manufacturing the modeled object 50, the residual powder in each part of the path 60 after the modeled object 50 is manufactured using the three-dimensional data. Determine removability. At this time, as will be described later, the internal structure examining unit 114 determines the removability of the residual powder based on the roughness of the inner wall surface of the path 60 in the path model. Further, the internal structure examining unit 114 may modify the path 60 so that the removability is improved after the determination of the removability of the residual powder.

<Three-dimensional data correction unit 116>
Next, the three-dimensional data correction unit 116 corrects the three-dimensional data acquired in the step S10 based on the removability determined in the step S20 (step S30). Specifically, the three-dimensional data correction unit 116 corrects the three-dimensional data acquired in the step S10 so that the removability determined in the step S20 is improved. More specifically, the three-dimensional data correction unit 116 corrects the three-dimensional data so as to improve the removability of the portion determined to have poor removability in the step S20. That is, in the three-dimensional data corrected by the three-dimensional data correction unit 116, the powder stack thickness (or the thickness of the hardened layer, the same applies hereinafter) and the arrangement of the path 60 are corrected so that the removability is improved. ing. Here, the “arrangement” includes the length, diameter, bending state (curvature), position (including distance from the outer surface of the modeled object 50, branching, etc.), and the like. In addition, when “function establishment” and “structure establishment” are examined in the process of S20, the three-dimensional data correction unit 116 further improves “function establishment” and “structure establishment”. You may correct the three-dimensional data acquired at the process of S10. Note that the correction of the arrangement of the path 60 itself may be performed by the three-dimensional data correction unit 116 or the internal structure review unit 114.

<Laminated modeling control unit 118>
The additive manufacturing control unit 118 uses the three-dimensional data corrected in step S30 to manufacture the object 50 by additive manufacturing as described above (step S40). And residual powder is removed using the 2nd fluid from the path | route 60 formed in the inside of the molded article 50 actually manufactured at the process of S40 (step S50).

  As described above, in the additive manufacturing method according to the first embodiment, the three-dimensional data related to the modeled object 50 is corrected so that the removability of the residual powder in the path 60 is improved. Therefore, the additive manufacturing method according to the first embodiment can satisfactorily remove the residual powder remaining in the path 60 formed in the actually manufactured object 50.

<Details of internal structure review unit 114>
FIG. 6 is a flowchart showing details of the step S20 in the flowchart shown in FIG. First, the internal structure review unit 114 arranges a route model using the three-dimensional data acquired in the process of S10 (step S210). For example, when the additive manufacturing method (step S20) is performed using a prototype, a prototype is manufactured using the additive manufacturing apparatus 1 using the three-dimensional data in step S10. Thereby, a path | route model is formed in the prototype of the molded article 50. FIG. For example, when the additive manufacturing method (step S20) is performed using CAE analysis, the route model is reproduced by computer simulation using three-dimensional data in step S10.

  Next, the internal structure examination unit 114 examines function feasibility (step S220). Then, the internal structure review unit 114 determines whether or not the function condition is satisfied (step S222). If the function condition is not satisfied (NO in S222), the process returns to S210. On the other hand, when the function condition is satisfied (YES in S222), the process proceeds to S230.

  When the function exhibited by the path 60 is a cooling function, the internal structure examining unit 114 causes the temperatures of the high temperature regions 92 and 94 (FIG. 4) when the cooling water is circulated through the path model and molding is performed using a mold. Is acquired and it is determined whether or not the temperature falls below a predetermined temperature (S222). Then, when the temperature is equal to or lower than the predetermined temperature, it is determined that the function condition is satisfied (YES in S222).

  When the process of S20 is performed using a prototype, in S220, cooling water is circulated through the path model formed in the prototype, and molding is performed with a mold related to the prototype. And the internal structure examination part 114 acquires the temperature of the location corresponding to the high temperature area | regions 92 and 94 in a prototype at that time. The temperature can be measured by, for example, thermography. In addition, when using a prototype, you may determine whether the conditions of a function are satisfied by detecting the presence or absence of the malfunction of a molded article or a metal mold | die.

  In addition, when the process of S20 is performed using CAE analysis, in S220, the internal structure examining unit 114 reproduces that the mold is formed in a state in which cooling water is circulated through the path model by computer simulation using CAE. To do. And the internal structure examination part 114 calculates the temperature of the high temperature area | regions 92 and 94 by the temperature analysis (cooling analysis) by CAE.

  If the conditions for the cooling function are not satisfied (NO in S222), the internal structure examining unit 114 changes the arrangement of the path model so as to satisfy the conditions for the cooling function in the process of S210. For example, the internal structure review unit 114 may increase the diameter of the path 60 (partial paths 62 and 66) close to the high temperature regions 92 and 94. Further, the internal structure reviewing unit 114 may bring the path 60 (partial paths 62 and 66) closer to the high temperature regions 92 and 94, or branch so as to newly arrange a partial path closer to the high temperature regions 92 and 94. It may be provided.

  When the function exhibited by the path 60 is soundproofing or vibration isolation, the internal structure reviewing unit 114 determines that the volume or vibration magnitude when the first fluid is circulated through the path model is a predetermined value or less. It may be determined whether or not (S222). Further, when the function exhibited by the path 60 is transport, the internal structure reviewing unit 114 determines whether or not the speed when transporting an object by circulating the first fluid through the path model is equal to or higher than a predetermined speed. May be determined (S222).

  Next, the internal structure review unit 114 examines structure feasibility (step S230). Then, the internal structure examining unit 114 determines whether or not the rigidity condition is satisfied (step S232). When the rigidity condition is not satisfied (NO in S232), the process returns to S210. On the other hand, when the rigidity condition is satisfied (YES in S232), the process proceeds to S240.

  Specifically, the internal structure review unit 114 acquires the distortion or deformation amount in the mold model when a load is applied to the model (mold model) of the model 50 having the path model therein, It is determined whether the amount of distortion or deformation is equal to or less than a predetermined allowable value (S222). Then, when the strain or deformation amount is equal to or less than a predetermined allowable value, it is determined that the rigidity condition is satisfied (YES in S222). In S230, strength evaluation may be performed instead of stiffness evaluation. In this case, determination of the strength condition may be performed using a stress value instead of the strain or deformation amount in the mold model.

  When the process of S20 is performed using a prototype, in S230, a rigidity test is performed on the prototype in which the path model is formed. And the internal structure examination part 114 acquires the distortion or deformation | transformation amount in the predetermined location at that time. The strain can be measured by attaching a strain gauge at a predetermined location. In addition, when using a prototype, you may determine the feasibility of a structure by detecting the malfunction of the molded article or metal mold | die by insufficient rigidity of a prototype.

  When the process of S20 is performed using CAE analysis, the internal structure review unit 114 performs structural analysis using FEM (Finite Element Method) in S230. Then, the internal structure review unit 114 calculates the strain or deformation amount at a predetermined location. Note that the internal structure review unit 114 may determine whether or not the stress value indicated by the stress distribution obtained by the structural analysis is equal to or less than an allowable value. Further, thermal stress may be taken into consideration in the structural analysis.

  If the condition is not satisfied (NO in S232), the internal structure examining unit 114 changes the arrangement of the route model so as to satisfy the rigidity condition in the process of S210. For example, the internal structure examining unit 114 may change the arrangement of the path 60 so that the path 60 is separated from the outer surface of the model 50.

  Next, the internal structure examining unit 114 examines the removability of the residual powder remaining in the path 60 (step S240). Then, the internal structure review unit 114 determines whether or not the removability condition is satisfied (step S242). If the removability condition is not satisfied (NO in S242), the process returns to S210. On the other hand, when the removability condition is satisfied (YES in S242), the process of S20 ends.

As described above, the internal structure review unit 114 determines the three-dimensional data before manufacturing the model 50 based on the roughness of the inner wall surface of the path 60 in the path model that simulates the path 60 using the three-dimensional data. The removability of the powder remaining in the path 60 after the shaped article 50 is manufactured is determined using (S242). Specifically, the internal structure review unit 114 circulates the second fluid in the route model, acquires at least one of the flow rate and the flow velocity at each location of the route model, and at least one of the flow rate and the flow velocity is predetermined. It is determined whether or not it is equal to or greater than a reference value (S242). Then, when at least one of the flow rate and the flow velocity is equal to or higher than a predetermined reference value, it is determined that the removability of the residual powder is good, that is, the removability condition is satisfied (YES in S242). That is, if the flow rate and flow velocity of the second fluid are large, the energy of the second fluid is increased, so that the removability of the residual powder can be improved. The “predetermined reference value” may be different at each location of the route 60 (partial routes 61 to 67 and bent portions 71 to 76 in FIG. 4). And the pressure loss by flow resistance has big influence on the flow volume and flow velocity in each location. As shown in FIG. 7, the pressure loss ΔP due to the flow resistance assumes that the path 60 is a cylinder, the inner diameter of the path 60 is D, the length of the path 60 is L, and the flow velocity of the fluid flowing through the path 60 is Assuming V, it is expressed by the following formula 1.
(Formula 1) ΔP = ρλLV ² / 2D
Here, ρ represents the density of the fluid, and λ represents the friction coefficient of the inner wall surface of the path 60. In the first embodiment, particular attention is paid to the friction coefficient of the path 60, and the correction coefficient determined based on the roughness of the inner wall surface of the path 60 is set to improve the accuracy of determination of the removability. By multiplying the friction coefficient of the inner wall surface, the friction coefficient of the inner wall surface of the path 60 is corrected.

(Relationship between powder thickness and friction coefficient)
In FIG. 8, the photograph which expanded the inner wall face of the path | route 60 is shown. As shown in FIG. 8, the inner wall surface of the path 60 formed by the additive manufacturing apparatus 1 has a regular wavy shape. Moreover, the unevenness | corrugation by this wavy shape has a positive correlation with the lamination thickness of powder. Accordingly, the thinner the laminated thickness of the powder, the more the roughness of the inner wall surface of the path 60 can be suppressed. However, if the laminated thickness of the powder is reduced, the modeling time is prolonged. On the other hand, when the powder lamination thickness is increased for the purpose of shortening the modeling time, the roughness of the inner wall surface of the path 60 is deteriorated. Therefore, when the process of S20 is performed using CAE analysis, the internal structure examining unit 114 multiplies the correction coefficient shown in FIG. 9 by the friction coefficient of the inner wall surface of the path 60 in the computer simulation by CAE. . That is, when the powder lamination thickness is standard, the correction coefficient is x1.0, and when the powder lamination thickness is a predetermined amount thicker than the standard thickness, the correction coefficient is x1.5. When the laminated thickness of the powder is a predetermined amount smaller than the standard thickness, the correction coefficient is set to smaller x0.5. Here, the standard lamination thickness of the powder is determined by the powder material characteristics, facility capacity, modeling time, and the like. According to the above correction, the flow resistance is appropriately increased / decreased according to the thickness of the stack relative to the standard stack thickness of the powder, and the determination of removability in consideration of the stack thickness is realized. .

(Relationship between direction of inner wall surface of path 60 and friction coefficient)
FIG. 10 shows an enlarged photograph of the cross section of the path 60. As shown in FIG. 10, the substantially downward ceiling surface of the inner wall surface of the path 60 is rougher than the other surfaces. This is because the powder is pulled downward by gravity in the process of melting and solidifying the powder on the ceiling surface. Since this phenomenon is closely related to the direction in which gravity acts, the roughness of the inner wall surface of the path 60 is closely related to the direction of the inner wall surface of the path 60. Specifically, as shown in FIG. 11, the ceiling surface 90 that is substantially downward of the inner wall surface of the path 60 can be evaluated as relatively rough, and the side wall surface 91 that is substantially laterally of the inner wall surface of the path 60 is It can be evaluated that it is not as rough as the ceiling surface 90. In short, it can be said that the inner wall surface of the path 60 becomes rougher as it goes downward. Therefore, when the process of S20 is performed using CAE analysis, the internal structure examining unit 114 multiplies the correction coefficient shown in FIG. 12 by the friction coefficient of the inner wall surface of the path 60 in the computer simulation by CAE. That is, the correction coefficient is set to x2.00 for the substantially downward ceiling surface 90 of the inner wall surface of the path 60, and the correction coefficient is set to x1.25 for the substantially lateral wall surface 91 of the inner wall surface of the path 60. . Moreover, what is necessary is just to set it as * 1.00 as a standard correction coefficient about the substantially upward part among the inner wall surfaces of the path | route 60. FIG. In addition, as shown in FIG. 11, it is good to set a correction coefficient to 1.50 as shown in FIG. According to the above correction, the friction coefficient of the inner wall surface of the path 60 can be corrected by appropriately taking into consideration the influence of gravity, and the determination of removability in consideration of the influence of gravity is realized.

  Each correction coefficient described above may be obtained as a theoretical value based on the three-dimensional data or the layer thickness of the powder, or may be determined statistically through repeated experiments and measurements.

  As described above, there are two methods for correcting the friction coefficient of the inner wall surface of the path 60, one that considers the laminated thickness of the powder and the other that considers the direction of the inner wall surface of the path 60. However, only one of these two methods may be adopted or at the same time. That is, in the step of determining removability, the thinner the inner wall surface of the path 60 is, the better the removability is. In addition, the lower the inner wall surface of the path 60 is, the better the removability is determined. . However, as can be seen by comparing FIG. 8 and FIG. 10, the direction of the inner wall surface of the path 60 has a greater influence on the roughness of the inner wall surface of the path 60 than the laminated thickness of the powder. That is, when the inner wall surface of the path 60 is facing downward, the inner wall surface of the path 60 is randomly roughened. Therefore, when these two methods are adopted at the same time, it is assumed that the orientation of the inner wall surface of the path 60 has a greater influence on the quality of the removal than the laminated thickness of the inner wall surface of the path 60. It is preferable to determine the removability by correcting the friction coefficient of the inner wall surface of the path 60 in consideration of the direction of the inner wall surface of the path 60 with priority over the stacking thickness. FIG. 13 shows a correction coefficient when the laminated thickness of the inner wall surface of the path 60 and the orientation of the inner wall surface of the path 60 are considered simultaneously. As shown in FIG. 13, the increase / decrease width of the correction coefficient due to the difference in the laminated thickness of the inner wall surface of the path 60 is 0.5 at the maximum, whereas the correction coefficient due to the difference in the direction of the inner wall surface of the path 60 The maximum increase / decrease width is 0.75. According to the correction coefficient described above, the removability can be appropriately determined based on the weight of the influence on the removability.

  In addition, when the process of S20 is performed using a prototype, in S240, determination of removability is performed with respect to the prototype in which the path model is formed. Specifically, in a prototype, the cross-sectional shape of a complicated shape part such as a branch part or a bent part of a route is converted into a limit sample or evaluation value, and converted into an index value, and an actual measurement value of flow rate or flow velocity and a laminated thickness are obtained. In association with each other, when producing a mold to be actually used, the removability is examined based on the above association, and correction work is performed to improve the removability as necessary.

  Moreover, preferably, the internal structure examining unit 114 determines the removability of the residual powder for a portion having a shape with a large pressure loss. As a result, the removability is determined after correcting the flow resistance in accordance with the roughness of the inner wall surface of the path 60 at a place where the removability may be poor, so that the entire path 60 is removed. There is no need to perform sex determination. Accordingly, it is possible to efficiently determine the removability.

  When the removability condition is not satisfied (NO in S242), in step S210, the internal structure examining unit 114 changes the powder stack thickness or the path model so as to satisfy the removability condition. Change the placement of. For example, the internal structure examining unit 114 may reduce the thickness of the laminated powder or place the path 60 slightly inclined with respect to the horizontal at a location determined to have poor removability.

(Modification)
Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, in the flowchart shown in FIG. 6, the order of steps S220, S230, and S240 can be changed as appropriate. Further, at least one of the steps S220 (S222) and S230 (S232) may not be performed.

  In the embodiment described above, the process of S20 in FIG. 3 (each process of FIG. 6) is performed by the control device 100, but is not limited to such a configuration. Each step of FIG. 6 may be performed by an operator if possible.

  In the above-described embodiment, the three-dimensional data acquired in step S10 of FIG. 3 includes the information on the route 60. However, the configuration is not limited to this. The three-dimensional data acquired in S10 includes only information on the outer shape of the model 50, and may not include information on the path 60 (information on the internal structure). In this case, a route model corresponding to the route 60 may be generated using the three-dimensional data in the step of S210. In this case, in the process of S30, the information on the route 60 corresponding to the route model generated in S20 may be added (reflected) to the three-dimensional data indicating the outer shape of the model 50 acquired in S10.

  In addition, as described above, after the model 50 is manufactured, residual powder that remains without being melt-bonded exists in the path 60. When removing this residual powder, for example, compressed air, high-temperature air, dry air, inert gas and other liquids, water, oil, cleaning agents, liquid abrasives, pipe brushes, and the like from the inlet 60a to the path 60 The device is injected and inserted, or the air in the passage 60 is sucked from the outlet 60b, for example.

  In the first embodiment described above, the flow rate and the flow velocity flowing through the path 60 are observed as one index of removability. However, the flow rate and the flow velocity are just indicators, and there are other alternatives. It may be adopted.

DESCRIPTION OF SYMBOLS 1 ... Laminate shaping apparatus, 50 ... Modeling thing, 51 ... Laminated powder, 52A-52L ... Powder layer, 60 ... Path | route, 61-67 ... Partial path | route, 71-76 * ..Bending part, 100 ... control device, 112 ... three-dimensional data acquisition part, 114 ... internal structure examination part, 116 ... three-dimensional data correction part, 118 ... layered manufacturing control part

Claims (5)

When manufacturing a three-dimensional shaped object by repeatedly laminating and melt-bonding powder, the powder is left unbonded in that part so that the powder is not partially melt-bonded. The additive manufacturing method for manufacturing the modeled object in which a hollow path through which the first fluid flows is formed,
Obtaining three-dimensional data related to the shaped object;
Based on the roughness of the inner wall surface of the route in the route model simulating the route using the three-dimensional data, the shaped object was manufactured using the three-dimensional data before the shaped object was manufactured. Determining the removability of the remaining powder in the later path;
Modifying the three-dimensional data so that the determined removability is improved;
And a step of manufacturing the model using the corrected three-dimensional data. In the step of determining the removability, it is determined that the removability is better as the lamination thickness of the inner wall surface of the path is smaller.
The additive manufacturing method according to claim 1. In the step of determining the removability, it is determined that the removability is poorer as the inner wall surface of the path is downward.
The additive manufacturing method according to claim 1 or 2. In the step of determining the removability, the removability is better as the lamination thickness of the inner wall surface of the path is thinner, and the removability is determined to be worse as the inner wall surface of the path is downward,
In the step of determining the removability, the direction of the inner wall surface of the path affects the quality of the removability rather than the stack thickness of the inner wall surface of the path. Determining the removability in consideration of the direction of the inner wall surface of the
The additive manufacturing method according to claim 1. The location of the route that is the target of the removability determination is determined according to the shape of the route.
The additive manufacturing method according to any one of claims 1 to 4.