JP4983768B2 - Modeling method by stereolithography - Google Patents

Description

The present invention relates to manufacturing method of granulated form thereof you produce shaped object in the optical shaping apparatus for producing a molded article in the powder body by sintering the irradiated with a laser.

  The present invention relates to a modeling method of a modeled object using a three-dimensional model necessary for manufacturing a modeled object with an optical modeling apparatus that irradiates a powder body with a laser and sinters the powdered body to manufacture a modeled object. .

  As a technique for manufacturing a mold or the like, there is a technique using a modeling apparatus that manufactures a model by sintering a metal powder by irradiating a laser.

FIG. 9 is an explanatory diagram illustrating an example of a modeling apparatus.
In this modeling apparatus, slice data of a cross section for each stacking thickness is created based on the three-dimensional data of the model to be modeled, and first, a base plate 2 in which a steel plate is coated with metal powder is placed on a platform 1 on the modeling side that can be moved up and down. Then, this is used as a base of the model 3, and the metal powder 4 is supplied on the base plate 2 with a thickness of one layer from the supply-side platform 5 by the recoater 6, and the laser 7 is applied to the metal powder 4 using the created slice data. , The metal powder 4 is sintered, the first metal powder layer is cured into a shape specified by the slice data, and the first layer and the base plate 2 are combined. Next, the platform 1 is lowered, the metal powder 4 is newly supplied in a thickness of one layer, and the metal powder is sintered by irradiating the metal powder layer with the laser 7 using the created slice data. The metal powder layer is cured into a shape specified by the slice data, and the first layer and the second layer are combined. This process is repeated to produce the model 3.

  In this device, if the laser irradiation rate is lowered, the metal powder is strongly sintered to increase the density of the shaped object, and if the laser irradiation rate is increased, the metal powder is less sintered and the density of the shaped object is increased. Is low.

As described above, when forming the insert of the molding die by sintering the metal powder by laser, the internal stress due to shrinkage caused by cooling generated heat on the surface of the molded object due to laser irradiation during modeling, the first A force in the peeling direction is generated with respect to the base plate in the layers after the layer, and the corner portion of the model is peeled off from the base plate, which may cause warpage.
FIG. 10 is an explanatory diagram showing the principle of the occurrence of peeling. First, heat is generated on the surface of the modeled object 3 by laser irradiation during modeling. And the force which is going to bend the whole modeling object generate | occur | produces by the shrinkage | contraction produced by this heat cooling, Thereby, the force of a peeling direction generate | occur | produces with respect to the base plate 2, and the corner part of the modeling object 3 becomes the base plate 2 And will peel off.

  This tendency is conspicuous because the peeling load increases as the thickness of the shaped object increases as in the shape of a mold. When using a molded object as a mold, the base plate is used as a part of the insert, so if peeling occurs, the required strength cannot be obtained, the adhesion with the base plate will deteriorate, and the entire surface will eventually peel off. Since there is a possibility that the dimensional accuracy deteriorates due to deformation due to warpage, re-modeling was necessary when peeling occurred.

  Further, when the mold has a nest on the surface, the nest is transferred to the surface of the molded product, and the surface quality of the molded product is deteriorated and the strength of the mold surface is also lowered. For this reason, the surface of the mold must be made dense. Therefore, when modeling the mold, when modeling the surface, the laser irradiation rate is low, and when modeling the inside, the laser irradiation rate is increased, the surface is high density, and the inside is dense. By creating a rough mold, the molding time is kept from becoming long.

  However, when modeling is performed so as to have such a double structure, the density difference between the surface and the interior increases, and cracking due to stress may occur during the modeling. In addition, in order to shorten the modeling time during internal modeling, a technique of irradiating the two layers once is also considered. When cracking occurs, the sintered metal has a property of shrinking, and therefore, it may be peeled off at a portion where the connection is weak.

  Further, when the mold has a double structure, strong shrinkage occurs on the high-density bottom surface side, so that the corner portion is easily peeled off from the base plate.

In order to solve the above-described problems, the invention of claim 1 is to supply a powder body on a base plate, irradiate the powder body with a laser to sinter the powder body and combine it with the base plate. In a modeling method by optical modeling using a modeling apparatus that supplies and sinters a body to produce a modeled object, a predetermined region on the inside of the modeled object is irradiated with laser at the lowest speed, and the inside from the inside to the outside headed to split into a plurality of areas, it characterized by fast stepwise laser irradiation speed toward the outside to the inside with respect to the respective regions.

The invention according to claim 2 is characterized in that the pillars that are in a lattice shape when viewed from above and penetrate the inner region surrounded by the base plate and the predetermined region are formed by laser irradiation at the same speed as the surface region. It shall be the.

In the first aspect of the present invention, since the bottom of the modeled object is modeled by performing laser irradiation at a speed next to a predetermined area inside from the surface of the modeled object, the shrinkage is suppressed while maintaining the strength. Since the force that pulls up the corner of the molded article when the bottom portion contracts is alleviated, an effect that peeling from the base plate can be prevented is obtained.
In addition, since the laser irradiation speed is gradually reduced from the innermost side of the modeled object toward the predetermined area to increase the density, the density difference does not become extremely large between the areas, and stress is increased. It is possible to prevent the molded object from being cracked due to the influence of. As a result, it is possible to increase the density of a predetermined region on the inner side from the surface of the modeled object, thereby reducing the nest of the surface and improving the quality of the surface of the molded product.

Furthermore, the connection between each area | region is strengthened by irradiating each area | region with a laser.
In addition, according to the invention of claim 2, since a lattice-like column having a high density is formed, the vertical connection is further strengthened, the internal peeling is eliminated, and the strength against the vertical pressure is also increased. The effect of doing is obtained.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a perspective view showing an example of a three-dimensional model structure showing a first embodiment of the present invention, FIG. 2 is a flowchart showing a flow of stereolithography of the present embodiment, and FIG. 3 is a first embodiment. It is explanatory drawing which shows an example of the molded article in FIG., And the three-dimensional model shown in FIG. 1 and the molded article shown in FIG. 3 are demonstrated according to the flow of FIG.
First, a three-dimensional model of a model is created (SA1). Next, a support shape for preventing separation from the base plate is added to the three-dimensional model (SA2). In the first embodiment, as shown in FIG. 3, the modeled object is provided with a taper-shaped peeling prevention support shape 8 at the boundary between the base plate 2 and the modeled object 3. As shown in FIG. 1, the anti-separation support shape 8 is added to the three-dimensional model 3 a of the model 3 so that the anti-separation support shape 8 is formed at the boundary of the modeled object 3. The peeling prevention support shape 8 is desirably a shape that gradually increases in thickness from the outermost portion, and when the shape of the molded article 3 is rectangular, the peeling prevention support shape 8 is formed at each corner. In the design stage of the molded article 3 itself, the anti-separation support shape is not considered, and the anti-separation support shape 8 is added according to the shape and size of the molded article 3 when creating the three-dimensional model 3a. .

Next, slice data is created from the three-dimensional model 3a to which the peeling prevention support shape 8 is added (SA3).
When the slice data is created, modeling conditions such as laser irradiation speed are set (SA4). And modeling is performed with a modeling apparatus using the created data (SA5).
Thereby, the molded article 3 provided with the peeling prevention support shape 8 as shown in FIG. 3 is manufactured.

FIG. 4 is an explanatory view showing the distribution of peeling load. FIG. 4 (a) shows the distribution of peeling load when there is a peeling prevention support shape. FIG. 4 (b) shows a conventional structure without a peeling prevention support shape for comparison. The distribution of peel load in the case of.
When the peeling prevention support shape 8 is provided, as shown in FIG. 4A, since the outermost portion of the peeling prevention support shape 8 is sufficiently thin at the start of modeling, the peeling load is small and the base plate 2 is sufficiently fixed. ing. As the lamination progresses, the peeling load gradually increases as the thickness of the peeling prevention support shape 8 increases. However, since the outermost part of the peeling prevention support shape 8 is sufficiently fixed, the peeling load does not peel off. When the stacking further proceeds and the part without the anti-peeling support shape 8 is formed, the molded article 3 is formed integrally with the anti-peeling support shape 8 and is therefore supported by the anti-peeling support shape 8 that is sufficiently fixed to the base plate 2. The peel load is weakened.

  When there is no peeling prevention support shape 8, as shown in FIG. 4B, as lamination progresses, the peeling load increases as it goes to the surface of the shaped article 3, and the shaped article 3 is easily peeled from the base plate 2. In particular, the corner portion is more easily peeled because the peeling load is larger. Therefore, as shown in FIG. 3, if the peeling prevention support shape 8 is formed at each corner, peeling can be prevented.

  FIG. 5 is an explanatory view showing an example of a modeled object according to the second embodiment of the present invention. FIG. 5 (a) is a plan sectional view and FIG. 5 (b) is a side sectional view. FIG. 6 is an external perspective view of a modeled object. As an example of the modeled object 3 according to the second embodiment, the surface has a rectangular parallelepiped recess, and two holes 3b are provided from the recess. FIG. 5A is a plan cross-sectional view of the shaped article 3 of FIG. 6 cut along the A line, and FIG. 5B is a plan cross-sectional view of the shaped article 3 of FIG. 6 cut along the B line. In the second embodiment, in the setting of the modeling conditions of the flow SA4 shown in FIG. 2, a setting in which the laser irradiation speed is gradually decreased from the inside toward the outside, and a grid-like column is provided inside the modeled object. At the same time, the setting for modeling is added. Note that. In the second embodiment, the anti-separation support shape may not be added.

In 2nd Embodiment, the inside of the molded article 3 is divided | segmented into a core 9a, the core 9b, the core 9c, and several area | regions toward inner side from the inner side, and the skin 10 used as the surface of the molded article 3 on the outer side of the core 9c. Is to shape. Further, the pillars 11 are arranged in a lattice shape when viewed from above and through the base plate 2 through the skin 10.
FIG. 7 and FIG. 8 are explanatory diagrams showing irradiation regions according to laser speeds, and details of modeling condition setting in the second embodiment will be described below. 7 is a cross-sectional plan view of each region of the shaped article shown in FIG. 5, and FIG. 8 is a side sectional view of each region of the shaped article shown in FIG.

  First, the skin 10 modeling data in which the region of the skin 10 shown in FIGS. 7A and 8A is specified and the bottom region specification is deleted is created. Next, the area of the core 9c shown in FIG. 7B and FIG. 8B is designated on the inner side of the skin 10 and the laser irradiation is performed for each layer, and the bottom area is deleted from the skin 10 below. The modeling data for the core 9c extended to is created. Next, the core 9b shown in FIGS. 7 (c) and 8 (c) is designated on the inner side of the core 9c, and each layer laser is designated to create modeling data for the core 9b. Next, the area designation of the core 9a shown in FIGS. 7D and 8D and the designation of irradiating each layer laser are performed on the inner part from the core 9b, and the modeling data for the core 4a is created.

Then, the slowest laser irradiation speed is set in the modeling data for the skin 10, and the laser irradiation speed higher than that of the skin 10 is set in the order of the cores 9c, 9b, and 9a.
Although not shown in FIGS. 7 and 8, the grid-shaped column 11 shown in FIG. 5 is also set to be modeled at the same slowest laser irradiation speed as that of the skin 10. When a model is manufactured with this setting, a model illustrated in FIG. 5 is obtained.

  In the modeled object shown in FIG. 5, the laser irradiation speed is gradually decreased from the core 9a toward the skin 10 to increase the density, so that the density difference does not become extremely large between the regions, and stress is increased. It is possible to prevent the molded object from being cracked due to the influence of. Thereby, the density of the skin 10 can be further increased, the nest of the surface can be reduced, and the quality of the surface of the molded product can be improved.

In addition, by modeling the bottom of the model 3 under the condition of the core 9c, the shrinkage is suppressed while maintaining the strength, and the force to pull up the corner of the model 3 when the bottom contracts is alleviated. Separation can be prevented.
Further, the cores 9a to 9c are reinforced by irradiating the lasers of each layer, and the connection between the upper and lower layers is strengthened. Furthermore, since the dense lattice-like pillars 11 are put up and down, the connection in the vertical direction is further strengthened. As a result, there is no internal peeling, and the strength against the pressure in the vertical direction increases.

In the second embodiment, the three-dimensional object 3 has a quadruple structure, but is not limited to this, and is changed in consideration of the size of the three-dimensional object. The present invention described above has been described as one in which a metal powder is sintered to produce a modeled object, but the present invention can also be applied to an optical modeling technique for modeling by curing other resins.
As described above, the present invention is a three-dimensional structure formed by stereolithography, and the taper-shaped anti-separation support shape is integrally formed at the boundary between the three-dimensional object and the base plate. It is possible to suppress the peeling from the base plate and the warping of the modeled object.

  In addition, the present invention divides the shaped object into a plurality of regions from the inside to the outside, and integrally forms the density so that the density increases stepwise from the inside to the outside, and the density is high from the bottom layer to the surface. Since the lattice-like columns are formed integrally, the surface density can be increased while suppressing the generation of internal stress, and deformation due to the molding pressure can be suppressed.

The perspective view which shows an example of the three-dimensional model structure which shows the 1st Embodiment of this invention Flow chart showing the flow of stereolithography of the present embodiment Explanatory drawing which shows an example of the molded article in 1st Embodiment Explanatory drawing showing distribution of peel load Explanatory drawing which shows an example of the molded article in the 2nd Embodiment of this invention External perspective view of the model Explanatory drawing showing irradiation area according to laser speed Explanatory drawing showing irradiation area according to laser speed Explanatory drawing showing an example of modeling equipment Explanatory drawing showing the principle of peeling

Explanation of symbols

2 Base plate 3 Model 3a Model 3D model 8 Anti-peeling support shape

Claims (2)

A powder body is supplied onto the base plate, the powder body is irradiated with a laser to sinter the powder body and bonded to the base plate, and thereafter, the powder body is sequentially supplied and sintered to produce a shaped object. In the modeling method by optical modeling using the device,
The predetermined area inside the surface of the modeled object is irradiated with the laser at the slowest speed, the inside is divided into multiple areas from the inside to the outside, and the laser irradiation speed is directed from the outside to the inside for each area. A modeling method by stereolithography characterized by speeding up . In the modeling method by the optical modeling of Claim 1 ,
A modeling method by optical modeling , wherein a pillar that is lattice-shaped when viewed from above and penetrates an inner region surrounded by the base plate and the predetermined region is formed by laser irradiation at the same speed as the surface region. .

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