JP5991574B2 - Manufacturing method of three-dimensional shaped object - Google Patents

Description

  The present invention relates to a method for manufacturing a three-dimensional shaped object. More specifically, the present invention manufactures a three-dimensional shaped object in which a plurality of solidified layers are laminated and integrated by repeatedly performing formation of a solidified layer by irradiating a predetermined portion of the powder layer with a light beam. Regarding the method.

  Conventionally, a method of manufacturing a three-dimensional shaped object by irradiating a powder material with a light beam (generally referred to as “powder sintering lamination method”) is known. In such a method, “(i) by irradiating a predetermined portion of the powder layer with a light beam, the powder at the predetermined portion is sintered or melt-solidified to form a solidified layer, and (ii) of the obtained solidified layer A three-dimensional shaped article is manufactured by repeating the process of “laying a new powder layer on the top and irradiating the same with a light beam to form a solidified layer” (see Patent Document 1 or Patent Document 2). When inorganic powder materials such as metal powder and ceramic powder are used as the powder material, the obtained three-dimensional shaped object can be used as a mold, and organic powder materials such as resin powder and plastic powder can be used. In such a case, the obtained three-dimensional shaped object can be used as a model. According to such a manufacturing technique, it is possible to manufacture a complicated three-dimensional shaped object in a short time.

  Taking a case where a metal powder is used as a powder material and the obtained three-dimensional shaped object is used as a mold, as shown in FIG. 1, first, a powder layer 22 having a predetermined thickness t1 is placed on a modeling plate 21, as shown in FIG. After the formation (see FIG. 1A), the solidified layer 24 is formed on the modeling plate 21 by irradiating a predetermined portion of the powder layer 22 with a light beam. Then, a new powder layer 22 is laid on the formed solidified layer 24 and irradiated again with a light beam to form a new solidified layer. When the solidified layer is repeatedly formed in this way, a three-dimensional shaped object in which a plurality of solidified layers 24 are laminated and integrated can be obtained (see FIG. 1B). Since the solidified layer corresponding to the lowermost layer can be formed in a state of being adhered to the modeling plate surface, the three-dimensional modeled object and the modeling plate are integrated with each other. The integrated three-dimensional shaped object and the modeling plate can be used as a mold as they are.

JP-T-1-502890 JP 2000-73108 A

  The inventors of the present application have found that a problem peculiar to the above-described powder sintering lamination method (that is, the additive manufacturing method using a light beam) can occur. Specifically, it has been found that the following problems occur.

  One of the features of the powder sintering lamination method is that a fluid path having an arbitrary shape (arbitrary overall shape and cross-sectional shape) can be arranged inside the three-dimensional shaped object (the shaped object is used as a plastic mold). In this case, the fluid path can be used as a water pipe for temperature adjustment). For example, assuming a case where a water pipe having a circular cross-sectional shape is arranged inside a modeled object, a portion corresponding to the circular portion may not be irradiated with a light beam. Since the powder remains in a local portion where the light beam is not irradiated, a cavity is formed when the powder is removed after shaping, and it can be used as a fluid path, that is, as a water pipe. However, in such a powder sinter lamination method, unmelted powder adheres around the melting point, so even if a fluid path is produced, the path inner diameter and path cross-sectional area become smaller than intended. (See FIGS. 19 and 20). As a result, it has been found that there is a problem that the amount of water that can be flowed into the fluid path of the modeled object is reduced and the temperature controllability is lowered. In addition, a mold-molded article having attached powder on the wall surface (fluid path forming surface) of the temperature adjusting water pipe is stored after removing water from the water pipe after use. It was found that there was also a problem that corrosion inside the water pipe progressed due to this residual moisture.

  Although it is desirable to remove the adhering powder, it is not easy to remove the powder adhering to the fluid path inside the molded article. Although straight pipes can be implemented by machining or electrical machining, it is difficult to carry out “arbitrary three-dimensionally arranged water pipes” that are characteristic of the powder sintering lamination method. Furthermore, if the water tube has a circular cross-sectional shape, the attached powder can be removed by cutting the “lower half surface that is not overhanging” in the middle of modeling. It is difficult to cut and remove the upper half surface "due to a steric hindrance (see FIG. 21).

  The present invention has been made in view of such circumstances. That is, an object of the present invention is to provide a technique for suitably removing the adhered powder from the “fluid path arbitrarily arranged in three dimensions” obtained by the powder sintering lamination method.

In order to solve the above problems, in the present invention,
(I) a step of irradiating a predetermined portion of the powder layer with a light beam to sinter or melt-solidify the powder at the predetermined portion to form a solidified layer; and (ii) a new powder on the obtained solidified layer Forming a layer, irradiating a predetermined portion of the new powder layer with a light beam to form a further solidified layer, and repeating the step of forming a three-dimensional shaped object,
In the steps (i) and (ii), by leaving a local region corresponding to a part of the internal region of the three-dimensional shaped object as a powder state portion, and finally removing the powder in the powder state portion, Form a fluid path inside the 3D shaped object,
Provided is a method for manufacturing a three-dimensional shaped object, in which after the three-dimensional shaped object is obtained, the fluid path is polished by flowing a “fluid containing an abrasive” as a swirling flow in the fluid path. .

  As a preferred aspect, in steps (i) and (ii), a protrusion is formed on the path forming surface of the fluid path, and in the polishing process, a swirl flow is generated in the fluid path due to the protrusion. You can do it. In such a case, the “projection” is preferably formed in a spiral shape.

  In another preferred embodiment, a swirl flow may be generated in advance in the fluid prior to introducing the fluid containing the abrasive into the fluid path.

  In yet another preferred embodiment, an internal member may be used for the polishing process. For example, an internal member that can generate a swirling flow in accordance with the flow of a fluid containing an abrasive may be provided in the fluid path. Further, an internal member may be rotatably provided in the fluid path, and the swirling flow may be generated by the rotation of the internal member.

  As an abrasive | polishing agent used for a grinding | polishing process, it is preferable to use the granular material whose particle size is 150 micrometers-300 micrometers, for example. Moreover, it is preferable that the abrasive | polishing agent density | concentration of the fluid used for a grinding | polishing process is 3 vol%-20 vol%. Note that the fluid itself of the medium containing the abrasive may be water, for example.

  In the present invention, even if the fluid path is arbitrarily three-dimensionally arranged inside the modeled object, the path surface (path forming surface) can be polished finely. Particularly in the present invention, even if the fluid path is three-dimensionally curved, the path surface can be polished substantially uniformly. Here, as a result of intensive studies by the inventors of the present application, it has been found that, by simply flowing an abrasive fluid, a portion that can be cleanly polished and a portion that is not cleanly appear due to a difference in fluid velocity (see FIG. 22). Therefore, in the present invention, the swirl flow is preferably used, thereby reducing the polishing unevenness and polishing the inner surface of the fluid path substantially uniformly. In other words, according to the present invention, even in the case of a “large or complicated curved fluid path”, it is possible to eliminate a difference between a portion that can be cleaned finely and a portion that does not.

  Since the present invention can polish the path surface of the fluid path substantially uniformly, even if the fluid path has a narrow shape (even if it corresponds to a water pipe diameter with a small channel diameter) When using an object as a mold, a large amount of temperature-controlled water can be secured. Also, being able to uniformly polish means that there is substantially no residual powder on the path surface and therefore remains after the fluid path is used as a water pipe (eg, a mold cooling water pipe). Residual moisture will be reduced. That is, in the present invention, it is possible to preferably avoid the inconvenience such as “water remains in the adhered powder portion after the mold is used and corrosion proceeds”.

  Furthermore, in the case where the polishing process is performed by mechanical processing or electrical processing, it is necessary to divide the modeled object in advance by cutting or the like, but in the present invention, the polishing process is performed by a simple operation such as flowing the abrasive fluid in a swirl flow. Can be implemented. In addition, “projections (for example, spiral projections)” that contribute to the generation of swirling flow can be easily and arbitrarily formed in the powder sintering lamination method, so they are uniform without significantly increasing production time and production costs. Thus, it can be said that efficient polishing treatment can be carried out efficiently.

Sectional view schematically showing the operation of the stereolithography combined processing machine FIG. 2A is a perspective view schematically showing a mode in which the powder sintering lamination method is performed (FIG. 2A: a composite apparatus including a cutting mechanism, FIG. 2B: an apparatus not including a cutting mechanism). The perspective view which showed typically the structure of the optical shaping complex processing machine by which a powder sintering lamination method is implemented The perspective view which showed typically the aspect by which the powder sintering lamination method is performed Flow chart of operation of stereolithography combined processing machine Schematic representation of the optical modeling complex processing process over time Schematic diagram showing the aspect of "polishing process using swirl flow" in the present invention The schematic diagram showing the aspect which forms a swirl flow only in the curved part of a fluid path / downstream part of a corner part Schematic diagram showing a mode of generating a swirling flow by forming protrusions (for example, spiral protrusions) on the path forming surface of the fluid path (FIG. 9A: sectional view, FIG. 9B: perspective section) (Figure) FIG. 10A is a schematic diagram showing an aspect in which the spiral protrusion is provided only on either the half-divided surface A or the half-divided surface B of the path forming surface (FIG. 10A: an aspect provided only on the half-divided surface A, FIG. b): Mode provided only on the half-divided surface B) Schematic diagram showing an aspect in which a swirling flow is generated by providing an internal member (FIG. 11 (a): an aspect in which an internal member contributing to the generation of swirling flow is provided in a fixed state, FIG. 11 (b): a fixed state A mode in which a swirling flow is generated with the fluid flow due to the presence of the internal member) Schematic diagram showing a mode in which a swirling flow is generated by providing an internal member (FIG. 12A: FIG. 12B when the swirling flow is generated by the rotation of the internal member with the fluid flow: When the swirling flow is generated by forcibly rotating the internal member, FIG. 12C: A mode in which swirling flow is generated due to the rotation of the internal member) Prior to the introduction of the abrasive fluid into the fluid path, a schematic diagram showing a mode in which a swirling flow is generated in advance in the fluid (a mode in which a swirling flow is generated at the path entrance). Schematic diagram showing an overview of the test equipment used in the examples Schematic showing the half-divided form of the work tube used in the example The graph which shows the test result in an Example (graph which shows the relationship between polishing time t and surface roughness Ra about a straight pipe | tube and a spiral pipe | tube). Photograph inside the spiral tube taken in the example Schematic diagram of the inside of the spiral tube in the example Schematic cross-sectional view and photograph showing an aspect where the adhering powder is present in the fluid path and the path diameter and cross-sectional area are reduced Schematic diagram showing a mode in which the adhering powder exists on the path forming surface of the fluid path Schematic showing that it is difficult to remove the overhang part by cutting Schematic diagram showing a mode in which "clean spots" and "other spots" occur due to the difference in fluid velocity when only abrasive fluid is flowed

  Hereinafter, the present invention will be described in more detail with reference to the drawings (the dimensional relationships in the drawings are merely examples and do not reflect actual dimensional relationships).

  In this specification, “powder layer” refers to, for example, “a metal powder layer made of metal powder” or “a resin powder layer made of resin powder”. The “predetermined portion of the powder layer” substantially means a region of the three-dimensional shaped article to be manufactured. Therefore, by irradiating the powder existing at the predetermined location with a light beam, the powder is sintered or melted and solidified to form the shape of the three-dimensional shaped object. Further, the “solidified layer” substantially means “sintered layer” when the powder layer is a metal powder layer, and substantially means “cured layer” when the powder layer is a resin powder layer. Meaning. The “local region (which is not irradiated with the light beam)” substantially refers to the “powder layer region corresponding to the fluid path” of the manufactured three-dimensional shaped object.

  The metal powder that can be used in the present invention is merely a powder mainly composed of iron-based powder, and may be nickel powder, nickel-based alloy powder, copper powder, copper-based alloy powder, and graphite. It may be a powder further comprising at least one selected from the group consisting of powder and the like. As an example, the amount of iron-based powder having an average particle size of about 20 μm is 60 to 90% by weight, the amount of nickel powder and / or nickel-based alloy powder is 5 to 35% by weight, copper powder and / or Examples thereof include metal powders in which the blending amount of both or any one of the copper-based alloy powders is 5 to 15% by weight and the blending amount of the graphite powder is 0.2 to 0.8% by weight.

[Powder sintering lamination method]
First, the powder sintering lamination method as a premise of the production method of the present invention will be described. For convenience of explanation, the powder sintering lamination method will be described on the premise that the material powder is supplied from the material powder tank and the powder material is formed by leveling the material powder using a squeezing blade. Further, in the case of the powder sinter lamination method, a description will be given by taking as an example a mode of composite processing in which cutting of a molded article is also performed (that is, assuming the mode shown in FIG. 2A instead of FIG. 2B) And). 1, 3 and 4 show the function and configuration of an optical modeling composite processing machine capable of performing the powder sintering lamination method and cutting. The optical modeling composite processing machine 1 includes “a powder layer forming means 2 for forming a powder layer by spreading a powder such as a metal powder and a resin powder with a predetermined thickness” and “in a modeling tank 29 whose outer periphery is surrounded by a wall 27. In FIG. 2, “a modeling table 20 that moves up and down”, “a modeling plate 21 that is arranged on the modeling table 20 and serves as a foundation of the modeling object”, “a light beam irradiation means 3 that irradiates a light beam L to an arbitrary position”, and “a modeling object” Cutting means 4 ”for cutting the periphery of the main body. As shown in FIG. 1, the powder layer forming means 2 includes “a powder table 25 that moves up and down in a material powder tank 28 whose outer periphery is surrounded by a wall 26” and “to form a powder layer 22 on a modeling plate”. The squeezing blade 23 ". As shown in FIGS. 3 and 4, the light beam irradiation means 3 includes a “light beam oscillator 30 that emits a light beam L” and a “galvanomirror 31 that scans (scans) the light beam L onto the powder layer 22 (scanning). Optical system) ”. If necessary, the light beam irradiation means 3 has beam shape correction means (for example, a pair of cylindrical lenses and a rotation drive mechanism for rotating the lenses around the axis of the light beam) for correcting the shape of the light beam spot. And an fθ lens. The cutting means 4 mainly includes “a milling head 40 that cuts the periphery of the modeled object” and “an XY drive mechanism 41 (41a, 41b) that moves the milling head 40 to a cutting position” (FIGS. 3 and 3). 4).

  The operation of the optical modeling complex machine 1 will be described in detail with reference to FIGS. 1, 5, and 6. FIG. 5 shows a general operation flow of the stereolithography combined processing machine, and FIG. 6 schematically shows the stereolithography combined processing process schematically.

  The operation of the optical modeling composite processing machine includes a powder layer forming step (S1) for forming the powder layer 22, a solidified layer forming step (S2) for forming the solidified layer 24 by irradiating the powder layer 22 with the light beam L, It is mainly composed of a cutting step (S3) for cutting the surface of the modeled object. In the powder layer forming step (S1), the modeling table 20 is first lowered by Δt1 (S11). Next, after raising the powder table 25 by Δt1, as shown in FIG. 1A, the squeezing blade 23 is moved in the direction of arrow A, and the powder disposed on the powder table 25 is moved onto the modeling plate 21. (S12), the powder layer 22 is formed to be equal to the predetermined thickness Δt1 (S13). Next, the process proceeds to the solidified layer forming step (S2), and the light beam L (for example, carbon dioxide laser (about 500 W), Nd: YAG laser (about 500 W), fiber laser (about 500 W), ultraviolet light, etc.) from the light beam oscillator 30) (S21), the light beam L is scanned to an arbitrary position on the powder layer 22 by the galvanometer mirror 31 (S22), and the powder is melted and solidified to form the solidified layer 24 integrated with the modeling plate 21. (S23). The light beam is not limited to being transmitted in the air, but may be transmitted by an optical fiber or the like.

  The powder layer forming step (S1) and the solidified layer forming step (S2) are repeated until the thickness of the solidified layer 24 reaches a predetermined thickness obtained from the tool length of the milling head 40, and the solidified layer 24 is laminated (FIG. 1). (See (b)). In addition, the solidified layer newly laminated | stacked will be integrated with the solidified layer which comprises the already formed lower layer in the case of sintering or melt-solidification.

  When the thickness of the laminated solidified layer 24 reaches a predetermined thickness, the process proceeds to the cutting step (S3). In the embodiment as shown in FIG. 1 and FIG. 6, the cutting step is started by driving the milling head 40 (S31). For example, when the tool (ball end mill) of the milling head 40 has a diameter of 1 mm and an effective blade length of 3 mm, a cutting process with a depth of 3 mm can be performed. Therefore, if Δt1 is 0.05 mm, 60 solidified layers are formed. At that time, the milling head 40 is driven. The milling head 40 is moved in the directions of the arrow X and the arrow Y by the XY drive mechanism 41 (41a, 41b), and the surface of the shaped object composed of the laminated solidified layer 24 is cut (S32). And when manufacture of a three-dimensional shape molded article has not ended yet, it will return to a powder layer formation step (S1). Thereafter, the three-dimensional shaped object is manufactured by repeating S1 to S3 and laminating a further solidified layer 24 (see FIG. 6).

  The irradiation path of the light beam L in the solidified layer forming step (S2) and the cutting path in the cutting step (S3) are previously created from three-dimensional CAD data. At this time, a machining path is determined by applying contour line machining. For example, in the solidified layer forming step (S2), contour shape data of each cross section obtained by slicing STL data generated from a three-dimensional CAD model at an equal pitch (for example, 0.05 mm pitch when Δt1 is 0.05 mm) is used. .

[Production method of the present invention]
The present invention is characterized in the processing mode of a shaped article obtained by the above-described powder sintering lamination method. Specifically, as shown in FIG. 7, the fluid path polishing process is performed by causing “fluid containing an abrasive” to flow as a swirl flow with respect to the fluid path formed inside the three-dimensional shaped object. I do.

  The fluid path (which may correspond to a “water pipe” in the case of using a modeled object for the mold) is formed in the process of the layered modeling of the three-dimensional modeled object. Specifically, a local region corresponding to a part of the internal region of the three-dimensional shaped object is left as a “powder state portion that is not irradiated with a light beam”, and the powder in the powder state portion is formed after molding or a solidified layer. By removing after formation, the fluid path can be formed. Since the fluid path is formed by a powder sintering lamination method, the overall shape and cross-sectional shape can be obtained arbitrarily, but the "fluid path forming surface (surface that forms the fluid path)" has a shaped object. The powder that did not contribute to the formation is adhered (that is, the “unsintered powder” is adhered to the fluid path surface). Therefore, in the present invention, in order to remove such adhering powder, a polishing process is performed by flowing a fluid containing an abrasive as a swirling flow in the fluid path (hereinafter, “comprising an abrasive”. "Fluid" is also referred to as "abrasive fluid" or simply "fluid").

  The “swirl flow” as used in the present specification substantially means a fluid flow that rotates in a circle. More specifically, for example, it refers to a flow that flows while rotating about the moving direction of the fluid in the fluid path (see the lower detailed view of FIG. 7). That is, in the present invention, the abrasive fluid is not simply caused to flow in the fluid path, but is caused to flow in a rotating flow.

  “Swirl flow” need not occur in the entire region of the fluid path. It is sufficient that a swirl flow is generated at least with respect to a region where a portion where the abrasive fluid can be simply polished and a portion where the abrasive fluid cannot be polished is generated. For example, when the fluid path is curved, as shown in FIG. 8, it is sufficient that a swirl flow is formed at least in the curved region and / or the vicinity thereof, particularly the downstream region of the channel corner portion.

  The swirl can be generated in the abrasive fluid in various ways. For example, as shown in FIG. 9, a protrusion 85 may be formed on the path forming surface of the fluid path 80, and a swirl flow may be generated in the abrasive fluid by the protrusion 85. In other words, when the abrasive fluid flows through the fluid path 80, a swirl flow may be generated in the abrasive fluid due to the interaction between the flow and the protrusions 85. In other words, the abrasive fluid may flow while interfering with the protrusions 85, and a swirl flow may be generated in the abrasive fluid with the interference.

  Such protrusions 85 can be formed during the powder sintering lamination method. That is, the projection 85 is formed by irradiating a part of the powder layer with a light beam and sintering or melting and solidifying the irradiated part. This means that the protrusion 85 is integrally obtained from the same material as the modeled object. The cross-sectional shape of the protrusion 85 is not particularly limited, and may be, for example, a semicircular shape (see FIG. 9), a rectangular shape, a square shape, or a triangular shape.

  The protrusions 85 do not necessarily have to be formed in the entire region of the flow path forming surface, but are formed in “regions where portions that can be polished cleanly by simply flowing the abrasive fluid through the fluid path, and regions that do not.” It is preferable to keep it. For example, when the fluid path is curved, the protrusion 85 may be provided only in the curved region and / or in the vicinity thereof (particularly, the “downstream region of the channel corner portion”) (see FIG. 8).

  As shown in FIG. 9, the protrusion 85 preferably has a spiral shape (spiral shape). That is, it is preferable that the protrusion 85 is formed so as to have a spiral shape, a spiral shape, a helical shape, or the like.

  The protrusion height H of the spiral protrusion 85 is preferably about D / 10 to 3D / 10, where D is the path diameter (see FIG. 9B). Similarly, for the spiral projection 85, the projection pitch P is preferably about 1D to 5D, for example (see FIG. 9A). Note that the spiral protrusion 85 may have a semicircular cross section as shown in FIG.

  As described above, the spiral protrusion 85 does not necessarily have to be provided on the entire flow path formation surface. When the fluid path is curved, the flow path formation surface (for example, the curved portion and / or its vicinity) (for example, You may provide only in "the downstream area of a flow-path corner part" (refer Fig.9 (a)). Further, the spiral-shaped protrusions 85 need not be formed entirely in the circumferential direction of the cross section of the fluid path, and may be formed only on a part thereof. For example, assuming a half-divided surface A and a half-divided surface B that are half-divided along the longitudinal axis of the channel, the spiral protrusion 85 is formed by the half-divided surface A or the half-divided surface B. It may be provided only in either of them (see FIG. 10). Even in such a case, the abrasive fluid flows while interfering with the projections 85 provided on the half-divided surface, so that a swirl flow is generated in the abrasive fluid.

  The swirling flow may be generated by using the internal member 86. That is, a member that generates a swirling flow in the fluid when the abrasive fluid flows may be inserted into the fluid path. As shown in FIG. 11, when the abrasive fluid passes through the internal member 86, the flow of the abrasive fluid is affected due to the three-dimensional form of the internal member 86. As a result, the polishing fluid is polished. A swirling flow is generated in the agent fluid. That is, the abrasive fluid flows while interfering with the internal member 86 installed in the fluid path, thereby generating a swirling flow in the abrasive fluid.

  As shown in FIG. 11, the internal member 86 preferably has, for example, a spiral shape (spiral shape). In other words, the internal member is preferably a helical member like a spring. That is, a preferable form of the internal member 86 is a spiral form, a spiral form, a helical form, or the like. However, the form of the internal member is not particularly limited as long as the swirling flow is generated, and various forms may be adopted.

  The internal member may be provided not only in a fixed state but also in a rotatable state. In such a case, the swirl flow is generated as the internal member rotates. That is, when the fluid containing the abrasive is flowed, the insertion member may be rotated so that a swirling flow is generated. For example, as shown in FIG. 12 (a), the internal member 87 may be rotated by receiving the flow of the abrasive fluid, thereby generating a swirling flow (see FIG. 12 (c)). ). Alternatively, as shown in FIG. 12 (b), an external force may be applied to the internal member 87 to forcibly rotate it, and a swirling flow is generated by such forced rotation of the internal member 87. You may make it do (refer FIG.12 (c)).

  Similar to the above-described embodiment, the internal member 87 does not necessarily have to be provided in the entire region of the fluid path. At least, “the point where the abrasive fluid can be polished cleanly by simply flowing the abrasive fluid in the fluid path, It is only necessary to be provided in the “region from which” appears. For example, when the fluid path is curved, the internal member 87 may be provided only in the curved region and / or the vicinity thereof, for example, the “downstream region of the channel corner” (see FIG. 8). . The internal member 87 can be provided by appropriately removing the “local powder state portion not irradiated with the light beam” in the lamination process of the solidified layer and disposing the internal member in the removed portion.

  In the present invention, the swirl flow is generated in at least a part of the fluid path, but the generation location is not limited to the inside of the fluid path but may be the outside thereof. That is, for example, as shown in FIG. 13, prior to introducing the abrasive fluid into the fluid path, a swirling flow may be generated in the fluid in advance. The means for generating the swirl flow in advance is not particularly limited, and the above-described “helical projection 85”, “internal members 86 and 87”, and the like may be used. In this aspect, since a swirling flow can be generated simply by providing an attached means after manufacturing the modeled object, the polishing process can be performed without affecting the manufacturing of the modeled product itself.

  Here, the abrasive fluid is not particularly limited as long as abrasive grains that function as an abrasive are contained in the liquid. In such an abrasive fluid, the abrasive grains are present in a dispersed / free state in the liquid. In view of this point, it can be said that the present invention performs the polishing process of the fluid path by supplying loose abrasive grains as a swirling flow into the fluid path.

  The abrasive itself is, for example, a granular material having a particle size (particularly an average particle size) of preferably 150 μm to 300 μm, more preferably 200 μm to 250 μm. Use of an abrasive having such a particle size is particularly desirable for removal of adhered powder (i.e., removal by the abrasive action of the abrasive fluid). The “average particle size” as used in the present specification was calculated as the number average of, for example, the particle size of 300 particles based on an electron micrograph or an optical micrograph of a granular material (ie, particles). (The "particle size" substantially refers to the maximum length among all the lengths of the particles in all directions).

  The material of the abrasive is preferably ceramic or metal. For example, the abrasive may be made of at least one material selected from the group consisting of alumina, diamond, boron nitride, zirconia, and silicon carbide.

  The medium liquid for dispersing and releasing the abrasive may be water, for example. Use of water is not only advantageous in terms of cost but also has an appropriate fluidity at room temperature, so that the abrasive can be suitably dispersed and released.

  The abrasive concentration of the fluid used for the polishing treatment is preferably about 3 vol% to 20 vol%, more preferably about 4 vol% to 15 vol%, still more preferably about 5 vol% to 10 vol% (abrasive fluid) Of total volume).

  As mentioned above, although embodiment of this invention has been described, it has only illustrated the typical example of the application scope of this invention. Therefore, those skilled in the art will readily understand that the present invention is not limited thereto and various modifications can be made.

  For example, the “helical protrusions 85”, “internal members 86 and 87”, and “means for generating a swirl flow beforehand” are not limited to being used alone, but may be used in an appropriate combination. It doesn't matter.

  In order to confirm the polishing treatment effect of the present invention, the following tests were conducted.

Test method (test equipment)
An overview of the test apparatus is shown in FIG. The test apparatus includes a hydraulic pump, a piston, a cylinder, a cartridge, and the like. The cartridges II and III are filled with water and abrasive grains, and a work tube (cooling tube) is installed between them. The cartridges I and IV are filled only with water, and serve as a buffer portion for preventing the filled abrasive grains from flowing into the cylinder. By pushing out the water filled in the cylinder, the filled abrasive grains pass through the work tube as a suspension and settle on the cartridge on the opposite side. At this time, the inner surface of the tube to be processed is polished by the abrasive grains in the suspension. When the moving direction of the piston is switched using the electromagnetic valve, the suspension can be continuously poured into the work tube.

(Processed pipe)
The powder used for the manufacture of the three-dimensional shaped object was a mixed powder containing iron-based powder, copper-based powder, nickel-based powder, and the like. The surface hardness of the shaped article obtained thereby was Vickers hardness of Hv = 330.

  In order to evaluate the inner surface of the tube to be processed, the tube to be processed was divided in parallel with the base plate by electric discharge machining after forming. A model diagram of the pipe to be processed after the division is shown in FIG. Those with no protrusions on the lower half were called “straight pipes”, and those with helical protrusions were called “spiral pipes”. FIG. 15A shows the upper half of them, FIG. 15B shows the lower half of the straight tube, and FIG. 15C shows the lower half of the spiral tube. The shape of the upper half is common to the street tube and the spiral tube. Therefore, the straight tube is a combination of FIG. 15 (a) and FIG. 15 (b), and the spiral tube is the figure. Polishing was performed using a combination of 15 (a) and FIG. 15 (c).

  The experimental conditions and dimensions of the pipe to be processed are shown in Table 1 below. As the abrasive grains, white alumina abrasive grains having a grain size of # 60 were used, and the cartridges II and III were filled with the abrasive grains so that the actual suspension concentration was 7.2 vol%. The diameter of the tube to be processed was 5 mm and the length was 80 mm. A semicircular protrusion having a diameter of 2 mm was formed on the spiral tube only on the lower half surface with a pitch of 10 mm. The surface roughness of these processed pipes was measured with a three-dimensional roughness meter.

(Test results)
FIG. 16 shows the relationship between the polishing time t and the surface roughness Ra for the “straight tube” and the “spiral tube”. The surface roughness of both the processed pipes decreased with the lapse of the polishing time, and in particular, the surface roughness rapidly decreased by 200 seconds. After 200 seconds, the decreasing change is moderate. Focusing on the surface roughness of 2000 seconds at the end of the test, the surface roughness of the “spiral tube” is smaller than that of the “straight tube”.

  From such a test result, it was found that if a swirl flow was generated using a spiral tube, the polishing property could be improved.

  17 and 18 show a photograph and a schematic diagram of the inside of a spiral tube obtained from the same test. As can be seen from the photograph and the like, it has also been found that the “swirl-flow polishing process” can reduce polishing unevenness and achieve a substantially uniform polishing.

DESCRIPTION OF SYMBOLS 1 Optical modeling combined processing machine 2 Powder layer formation means 3 Light beam irradiation means 4 Cutting means 19 Powder / powder layer (For example, metal powder / metal powder layer or resin powder / resin powder layer)
20 modeling table 21 modeling plate 22 powder layer (for example, metal powder layer or resin powder layer)
23 Squeezing blade (leveling plate / leveling blade)
24 Solidified layer (for example, sintered layer or hardened layer) or three-dimensional shaped object 25 obtained therefrom Powder table 26 Wall part 27 of powder material tank Wall part 28 of tank for forming material 28 Powder material tank 29 Modeling tank 30 Light beam oscillator 31 Galvano Mirror 32 Reflecting mirror 33 Condensing lens 40 Milling head 41 XY drive mechanism 41a X-axis drive unit 41b Y-axis drive unit 42 Tool magazine 50 Chamber 52 Light transmission window 80 Fluid path (flow path)
85 Protrusion 86 Internal member (path internal insert)
87 Internal member that can be rotated (insert inside the path)
100 Three-dimensional shaped objects (especially three-dimensional shaped objects with fluid paths)
L Light beam

Claims (7)

(I) irradiating a predetermined portion of the powder layer with a light beam to sinter or melt-solidify the powder at the predetermined portion to form a solidified layer; and (ii) a new powder on the obtained solidified layer. Forming a layer, irradiating a predetermined portion of the new powder layer with a light beam to form a further solidified layer, a method for producing a three-dimensional shaped object,
In the steps (i) and (ii), a local region corresponding to a part of the internal region of the shaped article is left as a powder state portion, and the powder in the powder state portion is finally removed, thereby Form a fluid path inside the model,
After the shaped object is obtained, a fluid containing an abrasive is flowed as a swirling flow into the fluid path to polish the fluid path ,
In the steps (i) and (ii), a protrusion is formed on the path forming surface of the fluid path, and the swirling flow is generated due to the protrusion in the polishing process . Production method. The method for producing a three-dimensional shaped article according to claim 1 , wherein the protrusion is formed in a spiral shape.   In the said grinding | polishing process, prior to introduce | transducing the said fluid into the said fluid path | route, the said swirl | flow is previously generated in this fluid, The three-dimensional shaped molded article of Claim 1 characterized by the above-mentioned. Method.   The method for producing a three-dimensional shaped object according to claim 1, wherein an internal member that generates the swirling flow in accordance with the flow of the fluid is provided in the fluid path in the polishing process. .   In the said grinding | polishing process, an internal member is rotatably provided in the said fluid path | route, The said swirl | vortex flow is generated by rotation of this internal member, The three-dimensional shaped molded article of Claim 1 characterized by the above-mentioned. Production method. The method for producing a three-dimensional shaped article according to any one of claims 1 to 5 , wherein a granular material having a particle size of 150 µm to 300 µm is used as the abrasive used in the polishing treatment. The method for producing a three-dimensional shaped object according to any one of claims 1 to 6 , wherein the fluid used in the polishing treatment has an abrasive concentration of 3 vol% to 20 vol%.