JP2012224907A - Method for manufacturing three-dimensionally shaped article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a three-dimensionally shaped article, for suitably coping with warp deformation of the shaped article.SOLUTION: The method for manufacturing a three-dimensionally shaped article includes repeating (i) a process for forming a solidified layer by irradiating the predetermined portion of a powder layer with a light beam so as to sinter or to melt and solidify the powder in the predetermined portion and (ii) a process for forming a new powder layer on the obtained solidified layer and irradiating the predetermined portion of the new powder layer with a light beam to form another solidified layer. The method is characterized by heat-treating a surface area constituting the outer surface of the three dimensionally shaped article in the surface area of a solidified layer by re-irradiating the surface area with a light beam.

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.

  In the powder sintering lamination method, generally, a three-dimensional shaped object is formed on a modeling plate. Specifically, a modeling plate is arranged on the modeling table and fixed with a bolt or the like, and a three-dimensional modeled object is formed on the modeling plate. 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 is formed in a state of being adhered to the modeling plate surface, the three-dimensional modeled object is obtained by being integrated with the modeling plate. Then, 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

  Here, since the three-dimensional shaped object is manufactured through irradiation with a light beam, the three-dimensional shaped object and the modeling plate that supports the three-dimensional shaped object are affected by the heat of the light beam. Specifically, the irradiated portion of the powder layer is once melted to be in a molten state and then solidified to form a solidified layer. However, a shrinkage phenomenon may occur during the solidification (see FIG. 2A). Although not bound by a specific theory, this shrinkage phenomenon is caused by the generation of stress when the molten powder cools and solidifies. On the other hand, the modeling plate that is integrated with the solidified layer (that is, the three-dimensional modeled object) is a rigid body made of steel or the like, and is fixed to the modeling table with bolts, etc. Stress may remain on the modeling plate. Therefore, if the bolt that fixes the modeling plate is removed, a phenomenon occurs in which the modeling object warps together with the plate due to the release of the residual stress (see FIG. 2B).

  The present invention has been made in view of such circumstances. That is, the subject of this invention is providing the manufacturing method of the three-dimensional shape molded article which coped with the warp deformation of a molded article suitably.

In order to solve the above problems, in the present invention,
(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,
Provided is a method for producing a three-dimensional shaped object, characterized by re-irradiating a light beam to a surface region constituting the outer surface of the three-dimensional shaped object among the surface areas of the solidified layer and heat-treating it. Is done.

  In a preferred embodiment, the light beam is re-irradiated after forming a solidified layer having an outer surface to be re-irradiated and before forming a new powder layer on the solidified layer. Do.

  In another preferable aspect, by re-irradiating the light beam, the “outer surface” (solidified layer surface region constituting the outer surface of the three-dimensional shaped object) and the solidified layer portion positioned below the “outer surface” are formed. Heat. Preferably, the solidified layer portion from the solidified layer having the “outer surface” to the solidified layer depth located on the lower layer side of the second to fourth layers is heated.

  In still another preferred embodiment, the residual stress of the solidified layer portion below the “outer surface” (solidified layer surface region constituting the outer surface of the three-dimensional shaped object) is reduced by heat treatment by re-irradiation with a light beam. Decrease.

  In still another preferred aspect, the light beam is re-irradiated except for an area to be surface-finished among “outer surface” (solidified layer surface area constituting the outer surface of the three-dimensional shaped object).

  The “outer surface” to be re-irradiated with the light beam is preferably obtained from the contour shape data of the three-dimensional shaped object. Specifically, when a solidified layer having an “outer surface” is an N layer and a solidified layer formed thereon is an N + 1 layer, a portion corresponding to the N layer from a contour shape of a portion corresponding to the N + 1 layer It is preferable to obtain an “outer surface” to be re-irradiated by subtracting the contour shape of the object.

  According to the manufacturing method of the present invention, it is possible to effectively reduce the residual stress that may occur when manufacturing the three-dimensional shaped object, and as a result, it is possible to reduce the warp deformation of the three-dimensional shaped object.

  In particular, in the present invention, the heat treatment performed to reduce the residual stress / warp deformation is performed through re-irradiation of the light beam. Therefore, such re-irradiation of the light beam can be performed accompanying the formation of the solidified layer. . Further, the region where the heat treatment is performed by re-irradiation is only “a surface region that becomes the outer surface of the three-dimensional shaped object”, and is limited to the last. Therefore, the time required for the heat treatment is short, and the entire manufacturing time is not unnecessarily long.

  If the residual stress / warp deformation can be suppressed, it becomes easy to obtain the shape accuracy of the three-dimensional shaped object. In this regard, in the prior art, in order to obtain the shape accuracy of the three-dimensional shaped object, it was necessary to design it after assuming a phenomenon such as “warping up” in advance. Shape accuracy can be obtained by re-irradiating a part of the surface region with a light beam. In other words, the present invention is very useful in that it is possible to omit such a design taking into account such a phenomenon that is difficult to predict by adding a simple process.

Sectional view schematically showing the operation of the stereolithography combined processing machine Sectional view schematically showing warpage deformation of a model FIG. 3A is a perspective view schematically showing an apparatus for performing stereolithography (powder sintering lamination method) (FIG. 3A: a composite apparatus provided with a cutting mechanism, FIG. 3B: no cutting mechanism is provided). apparatus) The perspective view which showed typically the aspect by which the powder sintering lamination method is performed The perspective view which showed typically the composition of the stereolithography compound processing machine which can carry out a powder sintering lamination method Flow chart of operation of stereolithography combined processing machine Schematic diagram showing the optical modeling complex processing process over time A diagram schematically showing the concept of the present invention The figure which showed typically the aspect which irradiates a light beam only to the solidification layer surface area | region used as an exposed surface (uppermost layer) in the three-dimensional shape molded article finally manufactured. A graph showing the residual stress that can be accumulated in a model Following the formation of the solidified layer of the third layer, a mode in which the light beam is re-irradiated to the “surface region a3 constituting the outer surface of the modeled object” existing in the solidified layer of the third layer is schematically shown. Cross section Following the formation of the solidified layer of the fourth layer, a mode in which the light beam is re-irradiated to the “surface region a4 constituting the outer surface of the modeled object” existing in the solidified layer of the fourth layer is schematically shown. Cross section Following the formation of the solidified layer of the fifth layer, a mode in which the light beam is re-irradiated to the “surface region a5 constituting the outer surface of the modeled object” existing in the solidified layer of the fifth layer is schematically shown. Cross section Explanatory drawing which showed the aspect which calculates | requires "outer surface" to which a light beam is re-irradiated from the outline shape data of a three-dimensional shape molded article Sectional drawing which showed the aspect which reirradiates a light beam except the part which surface-finishes. The perspective view which showed the aspect which surface-cuts with respect to the surface which forms cavity space at the time of metal mold | die use The perspective view which showed the aspect which surface-cuts with respect to a part of surface area which a core side and a cavity side will contact at the time of metal mold | die use Schematic diagram for explaining a mode in which the solidified layer portion shrinks and becomes lower than the surrounding powder layer

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  In the present specification, the “powder layer” substantially refers to, for example, a “metal powder layer made of metal 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. When the powder layer is a metal powder layer, “solidified layer” can correspond to “sintered layer” and “solidified density” can correspond to “sintered density”.

[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 the 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 material powder is leveled using a leveling plate to form a powder layer. Further, in the case of the powder sintering lamination method, a description will be given by taking as an example a mode of composite processing that also performs cutting of a molded article (that is, assuming the mode shown in FIG. 3A instead of FIG. 3B) And). 1, 4 and 5 show the function and configuration of a stereolithographic 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”. And the leveling plate 23 ". As shown in FIGS. 4 and 5, 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 a modeled object” and “an XY drive mechanism 41 (41a, 41b) that moves the milling head 40 to a cutting location” (FIGS. 4 and 4). 5).

  The operation of the optical modeling complex machine 1 will be described in detail with reference to FIG. 1, FIG. 6, and FIG. FIG. 6 shows a general operation flow of the optical modeling composite processing machine, and FIG. 7 schematically shows the optical modeling composite 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 leveling plate 23 is moved in the direction of arrow A, and the powder (for example, “average particle size 5 μm”) ˜iron powder of about 100 μm ”or“ powder of nylon, polypropylene, ABS, etc. having an average particle size of about 30 μm to 100 μm ”is transferred onto the modeling plate 21 (S12), and the powder layer is averaged to a predetermined thickness Δt1 22 is formed (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 such a lamination process, the newly-solidified solidified layer is integrated with the solidified layer forming the lower layer already formed during 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 shown in FIGS. 1 and 7, 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. 7).

  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 production method of the present invention has been devised in consideration of the stress that can be generated in a shaped article, with respect to the powder sintering lamination method described above. Specifically, in the present invention, as shown in FIG. 8, the light beam is re-irradiated to the surface region (“hatched portion” in the drawing) that constitutes the outer surface of the three-dimensional shaped object 24. Heat treatment is performed. That is, as shown in the drawing, the light beam is irradiated (heated) only to the uppermost layer of the three-dimensional shaped object 24.

  In the following description, an embodiment using “metal powder” as a powder (that is, an embodiment using a metal powder layer as a powder layer) will be described as an example. Incidentally, the metal powder used in the present invention is a powder mainly composed of an iron-based powder, and is optionally selected from the group consisting of nickel powder, nickel-based alloy powder, copper powder, copper-based alloy powder, graphite powder, and the like. (For example, the amount of the iron-based powder having an average particle size of about 20 μm is 60 to 90% by weight, either or both of the nickel powder and the nickel-based alloy powder. 5 to 35% by weight, copper powder and / or copper-based alloy powder or 5 to 15% by weight, and graphite powder is 0.2 to 0.8%. Examples thereof include metal powders having a weight%).

  In the present invention, the surface region of the formed solidified layer is irradiated again using the light beam used for forming the solidified layer. The surface area to which re-irradiation is performed is not necessarily the entire surface area of the solidified layer, but is merely a “surface area constituting the outer surface of the three-dimensional shaped object”. That is, the light beam is irradiated only to the solidified layer surface region that becomes the exposed surface in the finally manufactured three-dimensional shaped object. More specifically, as shown in FIG. 9, among the exposed surfaces of the three-dimensional shaped object, the solidified layer exposed surface that forms the upper side surface is irradiated with a light beam and heated.

  Such re-irradiation of the light beam relies on the graph result of FIG. 10 found in the creation process of the present invention. The inventors of the present application stated that “the residual stress that can be accumulated in the three-dimensional shaped object is concentrated near the uppermost surface of the object, that is, near the layer finally melted and solidified, and almost no stress is applied to the intermediate part. It tends to not remain ”(see graph of FIG. 10). Although not limited by a specific theory, this is because when the N layer in the middle part is melted and solidified (sintered), shrinkage stress is generated and remains, but the N + 1 layer, N + 2 layer, It is considered that the reason is that the Nth layer is subjected to thermal influence and stress relaxation when melt solidification (sintering) is repeated.

  Based on the graph of FIG. 10, even if the heat treatment for removing the residual stress is performed on the solidified layer corresponding to the intermediate layer, the intermediate layer has no meaning and only the processing time is increased. In the intermediate layer, the residual stress is inevitably reduced due to the influence of heat when the solidified layer is formed on the intermediate layer, and therefore, the meaning of actively performing the superimposed heat treatment is low. Therefore, it can be said that it is efficient to perform the heat treatment only on the surface of the uppermost layer where stress can remain, not the intermediate layer. Here, “the surface of the uppermost layer on which stress can remain” corresponds to “a surface region constituting the outer surface of the three-dimensional shaped object”. Therefore, in the present invention, only the “surface region constituting the outer surface of the three-dimensional shaped object” in the surface region of the solidified layer is subjected to heat treatment.

  Thus, in the present invention, the heat treatment by re-irradiation of the light beam is not performed on the entire layer / surface area, but only on the uppermost layer / surface area where residual stress is accumulated. Will be shortened as a whole, leading to a reduction in modeling time.

As the irradiation source of the light beam used for re-irradiation, the irradiation source used for forming the solidified layer can be used. Therefore, an apparatus for stereolithography (that is, a powder sintering lamination method) can be used as it is, which is not only advantageous in terms of equipment cost, but also because the same apparatus is used, the entire manufacturing process can be smooth. The irradiation condition of the light beam at the time of re-irradiation may be approximately the same as the irradiation condition of the light beam at the time of forming the solidified layer. For example, the irradiation energy density E of the light beam at the time of re-irradiation may be about 4 to 15 J / mm ² . Note that energy density E = laser output (W) / (scanning speed (mm / s) × scanning pitch (mm) (manufacturing conditions are, for example, powder lamination thickness: 0.05 mm, laser type: CO ₂ (Carbon dioxide gas) laser, spot diameter: 0.5 mm).

  In order to realize a suitable heat treatment, the irradiation condition of the light beam at the time of re-irradiation may be changed from the irradiation condition of the light beam at the time of forming the solidified layer. The irradiation conditions can be changed by (a) adjusting the irradiation energy (output energy) of the light beam, (b) adjusting the scanning speed of the light beam, (c) adjusting the scanning pitch of the light beam, ( d) It can also be carried out by adjusting the condensing diameter of the light beam. For example, in order to increase the heat treatment temperature during re-irradiation, in addition to (a) increasing the output energy of the light beam, (b) decreasing the scanning speed of the light beam, (c) reducing the scanning pitch of the light beam. (D) It can also be achieved by reducing the condensing diameter of the light beam. Conversely, in order to lower the heat treatment temperature at the time of re-irradiation, in addition to (a) reducing the irradiation energy (output energy) of the light beam, (b) increasing the scanning speed of the light beam, (c) light This can also be achieved by expanding the scanning pitch of the beam, or (d) increasing the condensing diameter of the light beam. These (a) to (d) may be performed independently, but may be performed in various combinations with each other.

  In view of the effect of reducing the residual stress due to annealing, it is preferable not to rapidly heat / cool the re-irradiated region. Therefore, if this matter is particularly emphasized, it is preferable to make the condensing diameter of the light beam at the time of re-irradiation larger than the condensing diameter at the time of forming the solidified layer.

  Of the surface area of the solidified layer, the portion corresponding to the “surface area constituting the outer surface of the three-dimensional shaped object” is irradiated with a light beam when the solidified layer is formed, and is also subjected to heat treatment after the solidified layer is formed. Is irradiated with a light beam. That is, the “surface region constituting the outer surface” is a region to which the light beam is irradiated twice during formation of the solidified layer and during heat treatment. In view of such aspects, this specification uses the term “re-irradiation”. In other words, the expression “re-irradiating the light beam” in this specification substantially refers to an aspect in which the light beam is irradiated not only during the solidified layer formation but also during the heat treatment after the solidified layer formation. ing.

  The re-irradiation of the light beam is preferably performed at the time when the target outer surface is formed. That is, it is preferable to perform re-irradiation after formation of a solidified layer having an outer surface to be re-irradiated and before formation of a new powder layer performed on the solidified layer. For example, assuming that a three-dimensional shaped article 24 as shown in FIG. 9 is manufactured, the “surface region a3 constituting the outer surface of the article” existing in the third solidified layer is shown in FIG. As shown, it is preferable to re-irradiate the light beam following the formation of the third solidified layer. Similarly, regarding the “surface region a4 constituting the outer surface of the modeled object” existing in the fourth solidified layer, as shown in FIG. 12, following the formation of the fourth solidified layer. It is preferable to perform re-irradiation with the light beam, and the “surface region a5 constituting the outer surface of the modeled object” existing in the fifth solidified layer is the fifth layer as shown in FIG. It is preferable to re-irradiate the light beam following the formation of the solidified layer of the eye. In this way, when the light beam is re-irradiated when the target outer surface of the target object appears, regardless of the shape of the three-dimensional target object, The light beam can be re-irradiated. For example, if the 3D model has a complicated shape and the light beam is re-irradiated after completion of the model, the path of the light beam is blocked by the model and the light beam reaches. There may be no areas. That is, it may not be possible to irradiate all of the “surface region constituting the outer surface of the model” with the light beam. For this reason, in the present invention, the irradiation of the light beam is performed at the time when the outer surface of the object to be modeled appears, that is, after the solidified layer having the outer surface of the model is formed, and Re-irradiation is preferably performed before a new powder layer is formed on the solidified layer.

  It is preferable to heat the outer surface of the object to be processed by re-irradiation with the light beam and to heat the solidified layer portion positioned below the outer surface (see FIG. 8). This is based on the graph result of FIG. That is, when the outer surface of the modeled object and the solidified layer portion below it are heated by re-irradiation with the light beam, the “residual stress in the portion A” in the graph of FIG. 10 can be reduced. The portion A in the graph of FIG. 10 corresponds to a portion from the uppermost layer of the model to the lower layer of about 2 to 7 layers. Therefore, when the solidified layer portion is heated by re-irradiation with the light beam from the outer surface layer to be processed to the solidified layer depth of 2 to 7 lower layers, preferably 2 to 4 lower layers, the remaining amount remains in that portion. Can be effectively reduced (the thickness of each solidified layer is, for example, about 0.02 mm to 0.08 mm). While not being bound by a specific theory, at the time of re-irradiation, the “solidified layer portion positioned below the outer surface” is suitably subjected to the annealing effect, whereby the residual stress of that portion is reduced. It is considered to be reduced.

  The “outer surface” to be re-irradiated with the light beam can be obtained from the contour shape data of the three-dimensional shaped object (see FIG. 14). Specifically, the re-irradiation region of the light beam can be obtained based on the contour shape data of each layer obtained by slicing the 3D model shape data used when laminating and sintering.

  Specifically, assuming that the solidified layer having the “outer surface” is an N layer and the solidified layer formed thereon is an N + 1 layer, the “N layer layer contour shape data corresponding to the N + 1 layer” is derived from the “N layer. The “outer surface” that is the object of re-irradiation can be obtained by subtracting the “contour shape data of the shaped part corresponding to“. For example, the re-irradiation region of the light beam performed in the second layer is a portion remaining by subtracting the contour shape of the third solidified layer from the contour shape of the second solidified layer (see FIG. 14). As shown in the drawing, such a portion is “painted” in the second layer, but becomes “not painted” in the third layer.

  Based on the re-irradiation area determination scheme as described above, the present invention extracts, in each layer, a portion where there is no filled area above the layer (the hatched portion in FIG. 8), and light is applied to the portion. It can be said that the residual stress is removed by re-irradiating the beam. A portion having no filled area above is extracted based on slice data (contour line data of each layer) used for modeling. On the other hand, the portion having the filled region above the target layer is annealed by the heat effect of the upper layer sintering, and the residual stress is removed.

  Even when heat treatment by re-irradiation of the light beam is performed over a plurality of layers, that is, when the “outer surface of the object” and the solidified layer portion located therebelow are heated by re-irradiation of the light beam, The re-irradiation area can be obtained from the “shape data”. For example, when heat treatment by re-irradiation of the light beam is performed over the K layer, the re-irradiation range of the N-th layer light beam is a portion obtained by subtracting the N + K-th layer contour shape from the N-th layer contour shape.

  In the manufacturing method of the present invention, the light beam is re-irradiated only to the region constituting the outer surface of the modeled object among the surface regions of the solidified layer, but there is a region where the surface finishing is finally performed. Then, it is preferable to perform re-irradiation except the part (refer FIG. 15). This is because although the residual stress is accumulated in the surface layer portion, when a surface finishing process such as a surface cutting process is performed, such a residual stress accumulation part is removed as a result. That is, since the region where the surface finishing process is to be performed does not require the residual stress removal process by the heat treatment, the light beam is not re-irradiated even if the surface area is the outer surface of the modeled object.

  Here, in the manufacture of a three-dimensional shaped object, surface cutting may be performed only on a necessary part in consideration of the use of the modeled object (particularly, surface cutting is performed on a surface area where force is applied when using the three-dimensional object). Preferably processed). For example, when a three-dimensional shaped object is used as a core-side or cavity-side mold, surface cutting may be performed on a surface that forms a cavity space when the mold is used (see FIG. 16). Further, a part of the surface region (particularly the annular surface region located just outside the cavity space forming surface) where the core side and the cavity side come into contact when the mold is used may be cut. (See FIG. 17). Therefore, in the present invention, it is preferable to re-irradiate the light beam except for such a surface cutting region. As a result, the re-irradiation range can be reduced, and the heat treatment time is shortened as a whole, so that more efficient modeling is realized.

  As described above, the preferred embodiment of the present invention has been described mainly. However, the present invention is not limited to this, and those skilled in the art can easily understand that various modifications can be made. For example, the following modifications can be considered.

In the above description, the aspect in which the re-irradiation of the light beam is performed mainly when the “outer surface” as the target appears, but the present invention is not necessarily limited to such an aspect. For example, the light beam may be irradiated to the “outer surface” in a lump after the manufacturing of the molded article is completed.

In the present invention, the light beam is re-irradiated after a solidified layer having an outer surface to be re-irradiated is formed, and a new powder layer is formed on the solidified layer. Although it is preferably performed before formation, the surrounding powder may be removed in advance prior to such re-irradiation. As shown in FIG. 18, this particularly takes into account that the solidified layer portion 24 may shrink and become lower than the surrounding powder layer 22 when the solidified layer is formed. That is, such a raised powder layer portion 22 is not convenient for re-irradiation of the solidified layer, and therefore it is preferable to remove it before re-irradiation.

Furthermore, in the above description, re-irradiation has mainly been described with respect to an embodiment in which a light beam irradiation source used for forming a solidified layer is used, but the present invention is not necessarily limited to such an embodiment. For example, as the re-irradiation source, a heat source different from the light beam irradiation source for optical modeling, such as an arc discharge power source or a thermal spray source, may be used.

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 Leveling plate 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 modeling tank 28 Powder material tank 29 Modeling tank 30 Light Beam oscillator 31 Galvano mirror 32 Reflection 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 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,
Of the surface region of the solidified layer, the surface region constituting the outer surface of the three-dimensional shaped object is re-irradiated with the light beam and subjected to heat treatment, thereby producing a three-dimensional shaped object Method.   The re-irradiation is performed after forming the solidified layer having the outer surface to be re-irradiated and before forming the new powder layer on the solidified layer, The manufacturing method of the three-dimensional shaped structure according to claim 1.   The three-dimensional shaped object according to claim 1 or 2, wherein the re-irradiation heats the surface region constituting the outer surface and the solidified layer portion positioned below the surface region. Production method.   The method for producing a three-dimensional shaped structure according to claim 3, wherein the solidified layer portion is heated from the solidified layer having the outer surface to a depth of the solidified layer located on the lower layer side of 2 to 4 layers.   The method for manufacturing a three-dimensional shaped article according to claim 3 or 4, wherein the heat treatment reduces stress remaining in a solidified layer portion below the surface region constituting the outer surface. .   6. The three-dimensional shaped article according to claim 1, wherein the re-irradiation is performed except for a region to be subjected to a surface finishing process among the surface regions constituting the outer surface. Method. The outer surface to be re-irradiated is obtained from the contour shape data of the three-dimensional shaped object,
When the solidified layer having the outer surface is an N layer and the solidified layer formed thereon is an N + 1 layer, a molded article of a portion corresponding to the N layer from a contour of a molded article corresponding to the N + 1 layer. The method for manufacturing a three-dimensional shaped object according to any one of claims 1 to 6, wherein the outer surface to be re-irradiated is obtained by subtracting a contour shape.