JP2004142427A - Manufacturing process for three-dimensionally shaped product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the bonding strength at the transitional part from a high density sintering layer to a low density sintering layer. <P>SOLUTION: In manufacturing a three-dimensionally shaped product which has multiple sintering layers laminated and integrated therein by the repetition of forming a sintering layer by irradiating a light beam L on a specified part of the layer of a powder material and sintering the powder of the specified part, a high density sintering layer 11H formed under a high sintering condition and a low density sintering layer 11L formed under a low sintering condition are selectively formed and, in shifting from the high sintering condition to the low sintering condition, a medium density sintering layer 11M is formed on the high density sintering layer 11H by irradiating the light beam under a medium sintering condition between the both conditions, and on this medium density sintering layer 11M there is formed the low density sintering layer 11L. Interposing the medium density sintering layer between the high and low density sintering layers prevents the lowering of the bonding strength. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for producing a three-dimensional shaped article, which produces a three-dimensional shaped article by sintering and hardening a powder material with a light beam.

There is a method for producing a three-dimensional shaped object known as stereolithography. The manufacturing method disclosed in Japanese Patent No. 2620353 (Patent Document 1) sinters (fuses) the powder at a corresponding portion by irradiating a predetermined portion of the layer of the inorganic or organic powder material with a light beam. A sintered layer is formed by coating a new layer of the powder material on the sintered layer, and a predetermined portion of the powder layer is irradiated with a light beam to sinter the powder at the corresponding portion, thereby lowering the lower layer. By repeating the formation of a new sintered layer integrated with the sintered layer, a powder sintered part (three-dimensional shaped object) in which a plurality of sintered layers are laminated and integrated is created. There is a device such as a machining center because a light beam is irradiated based on cross-sectional shape data of each layer generated by slicing a model, which is design data (CAD data) of a three-dimensional shaped object, into a desired layer thickness. 3D shape modeling of any shape even without Addition can be produced, compared to the manufacturing method such as by cutting, it is possible to obtain a molded article rapidly desired shape.

At this time, considering problems such as warping and cracking due to modeling time and internal stress, the entire model is not finished with uniform density under uniform sintering conditions, but only necessary parts are subjected to high sintering conditions. It is preferable that the high density sintered layer is formed and the other part is formed as a low density sintered layer under low sintering conditions. For example, when the molded article to be manufactured is an injection mold, it is preferable to finish the surface layer portion and the cooling water piping portion to which the molded product is transferred at a high density and the other portions at a low density.

By the way, the high-density sintered layer formed under high sintering conditions has a very clean finished surface because the powder is almost completely melted and solidified. Although no leakage occurs, the density of the powder layer in which the powder is thinly spread is 50 to 60%, whereas the high-density sintered layer has a density of almost 100%. As described above, when the high-density sintered layer 11H is formed by irradiating the powder layer 10 formed with the thickness t0 with the light beam L under the high sintering condition, the high-density sintered layer is more than the surface of the powder layer 10. The surface of 11 will be lowered by δ.

In addition, as shown in FIG. 12, when the thickness of the powder layer 10 to be formed is determined by the constant descending amount of the stage 20, the thickness of the powder layer 10 formed on the high-density sintered layer 11H is a design value. When the powder layer 10 is sintered under high sintering conditions to form a high-density sintered layer 11H, the surface of the high-density sintered layer 11 is larger than the surface of the powder layer 10. Is lowered by the step δa (δa> δ).

Further, when the powder layer 10 is formed and this time the low-density sintered layer 11L is formed under low sintering conditions, the thickness of the powder layer 10 at this time is higher than the design value t by the step δa as shown in FIG. Only thicker.

Here, the light beam L irradiated under the low density sintering condition is determined on the premise of the powder layer 10 having a thickness t, so that the step δa is thicker than the design value t. For the powder layer 10 that is present, the bonding force (adhesion) with the high-density sintered layer 11H located in the lower layer is weak even if the powder layer 10 cannot be sintered to the lower part or can be sintered. Thus, only the low-density sintered layer 11L that easily peels off can be obtained.
Japanese Patent No. 2620353

The present invention has been made in view of the above points. The object of the present invention is to provide a three-dimensional shaped object that can increase the bonding force of the portion that moves from the high-density sintered layer to the low-density sintered layer. To provide a manufacturing method.

Therefore, the present invention irradiates a predetermined portion of the layer of the inorganic or organic powder material with a light beam to sinter the powder at the corresponding portion to form a sintered layer, and the powder material is formed on the sintered layer. A plurality of layers are formed by repeatedly forming a new sintered layer integrated with the lower sintered layer by coating a new layer and irradiating a predetermined part with a light beam to sinter the powder at the corresponding part. When manufacturing a three-dimensional shaped object in which sintered layers are laminated and integrated, a high-density sintered layer formed under high sintering conditions and a low-density sintered layer formed under low sintering conditions are selectively formed. In addition, during the transition from the high sintering condition for the high-density sintered layer to the low sintering condition for the low-density sintered layer, the medium-density sintering irradiated with the light beam under the intermediate sintering condition of both conditions The first step is to form a binder layer on the high-density sintered layer and to form a low-density sintered layer on the medium-density sintered layer. It has a feature of. By interposing a medium density sintered layer between the high density sintered layer and the low density sintered layer, a decrease in the bonding force is prevented.

At this time, a plurality of medium density sintered layers are laminated, and the sintering conditions for these medium density sintered layers are temporarily brought close to the low sintering conditions for the low density sintered layer, and the medium density sintered layer of the upper layer is sintered. The density of the sintered layer is reduced by increasing the density of the sintered layer, so that the characteristic difference between the high-density sintered layer and the low-density sintered layer is smoothed. The medium density sintered layer may be formed under appropriate sintering conditions.

The present invention also provides a method for irradiating a predetermined portion of a layer of an inorganic or organic powder material with a light beam to sinter the powder at the corresponding portion to form a sintered layer, and forming a new powder material on the sintered layer. A plurality of firings by repeatedly forming a new sintered layer that is integrated with the underlying sintered layer by irradiating a predetermined portion with a light beam and sintering the powder at that location to sinter the desired layer. When manufacturing a three-dimensional shaped object in which the layers are laminated and integrated, a high density sintered layer formed under high sintering conditions and a low density sintered layer formed under low sintering conditions are selectively formed. In addition, the thickness of the uppermost high-density sintered layer is smaller than a predetermined value when shifting from the high-sintered condition for the high-density sintered layer to the low-sintered condition for the low-density sintered layer. Another feature is to provide a powder layer and sinter this powder layer under low sintering conditions to form a low density sintered layer. It is. The thickness of the powder layer used as the low density sintered layer is controlled so as not to be too thick.

The present invention also provides a method for irradiating a predetermined portion of a layer of an inorganic or organic powder material with a light beam to sinter the powder at the corresponding portion to form a sintered layer, and forming a new powder material on the sintered layer. And repeatedly forming a new sintered layer that is integrated with the underlying sintered layer by irradiating a predetermined portion with a light beam to sinter the powder at that location and sintering the powder at that location. The process of removing the surface part and / or unnecessary part of the shaped object created so far after the formation of the layer is inserted into the process of creating the sintered layer multiple times, and the multiple sintered layers are laminated and integrated In producing a three-dimensional shaped article, a high-density sintered layer formed under high sintering conditions and a low-density sintered layer formed under low sintering conditions are selectively formed, and a high-density sintered layer is formed. In transition from high sintering conditions for low-sintering conditions for low-density sintered layers, A powder layer having a thickness smaller than a predetermined value is provided on the upper high-density sintered layer, and this powder layer is sintered under high sintering conditions to form an excessive high-density sintered layer, and then the excessive high-density sintered layer is formed. It is characterized by forming a low density sintered layer on the bonding layer. After the step is filled with the high-density sintered layer, the low-density sintered layer is formed.

When providing a powder layer with a thickness smaller than a predetermined value on the uppermost high-density sintered layer, the amount of descent that determines the thickness of the powder layer of the stage on which the molded object formed so far is set to zero The next powder layer may be formed. The time required for lowering the stage can be reduced.

In the transition from high sintering conditions for high-density sintered layers to low sintering conditions for low-density sintered layers, Determine the thickness of the powder layer and the sintering conditions for this powder layer, and determine the thickness of the next powder layer based on the measurement results of the driving load of the blade that smoothes the surface of the powder layer during the previous powder layer formation. You may determine the sintering conditions of this powder layer. It can be reliably prevented that the thickness of the powder layer as the low density sintered layer becomes too thick.

In addition, the present invention selectively forms a high-density sintered layer formed under high sintering conditions and a low-density sintered layer formed under low sintering conditions, and provides high sintering for high-density sintered layers. In the transition from the condition to the low sintering condition for the low density sintered layer, the high density sintered layer is formed to a height higher than the design value, and then the high density sintered layer is cut and removed to the design value. It is characterized by forming a low density sintered layer. By adding the high-density sintered layer to a height at which the low-density sintered layer originally starts, the thickness of the powder layer used as the low-density sintered layer is set to the original value.

As described above, in the present invention, the presence of the medium density sintered layer interposed between the high density sintered layer and the low density sintered layer, the control of the thickness of the powder layer, or the excessive high density sintered layer. Since the thickness of the powder layer used as the low-density sintered layer is not excessively increased due to the formation of the layer, separation may occur between the low-density sintered layer and the high-density sintered layer. There is nothing.

Hereinafter, the present invention will be described in detail based on an example of an embodiment. As an apparatus for producing a three-dimensional shaped object by stereolithography, any form may be used, but in the illustrated example, a modeling tank 25 is used. A stage 20 that moves up and down in the space surrounded by the outer periphery is arranged, and the powder layer 10 having a predetermined thickness is obtained by smoothing the inorganic or organic powder material supplied onto the stage 20 in the modeling tank 25 with a squeezing blade. And forming the sintered layer 11 by irradiating a predetermined portion of the powder layer 10 with a light beam (laser) L through a scanning optical system.

Further, as the light beam output means for outputting the light beam L, one that can change the scanning pitch and scanning speed of the light beam L is used, and the high sintering is achieved by reducing the scanning pitch or slowing the scanning speed. The high-density sintered layer 11H is formed at the time of irradiation under conditions, and the low-density sintered layer 11L can be formed at the time of irradiation under low-density conditions where the scanning pitch is roughened or the scanning speed is increased. The condition may be changed by changing the output itself of the light beam output means.

As shown in FIG. 1, two high-density sintered layers 11H and 11H are formed on the stage 20 under high sintering conditions (for example, laser output 200W, scanning pitch 0.2 mm, scanning speed 50 mm / sec). Thereafter, when the low density sintered layer 11L is formed under low sintering conditions (for example, laser output 200W, scanning pitch 0.5 mm, scanning speed 300 mm / sec), sintering conditions intermediate between the two conditions (for example, laser output 200W). The medium density sintered layer 11M irradiated with the light beam L at a scanning pitch of 0.3 mm and a scanning speed of 100 mm / sec is first formed, and then the low density sintered layer 11L is formed. Even in the case of the powder layer 10 having a thickness that cannot be applied sufficiently with the light beam L under the low sintering condition for forming the low density sintered layer 11L, the light beam L under the intermediate sintering condition has sufficient heat. Since it can be added, peeling does not occur between the high-density sintered layer 11H.

At this time, as shown in FIG. 2, a plurality of medium density sintered layers 11Ma, 11Mb, and 11Mc are formed, and the sintering conditions for these medium density sintered layers 11Ma, 11Mb, and 11Mc are temporarily low-density sintered. You may make it approach the low sintering conditions for layer 11L. For example, the medium density sintered layer 11Ma in contact with the high density sintered layer 11H has a laser output of 200 W, a scanning pitch of 0.3 mm, and a scanning speed of 100 mm / sec. The medium density sintered layer 11Mc that comes into contact with the low density sintered layer 11L under the sintering conditions of pitch 0.35 mm and scanning speed 150 mm / sec has a laser output of 200 W, a scanning pitch of 0.4 mm, and a scanning speed of 200 mm / sec. Sintering is performed under sintering conditions.

Further, after the formation of the high-density sintered layer 11H, as shown in FIG. 3, the height difference probe δa between the surface of the powder layer 10 and the surface of the high-density sintered layer 11H is set to a height measuring probe P or the like. To obtain the thickness (t + δa) of the next powder layer 10 and form the medium density sintered layer 11M under the medium sintering conditions corresponding to the value of the thickness (t + δa). . Note that the intermediate sintering conditions corresponding to the value of the thickness (t + δa) are determined in advance from experimental results and the like.

Figure 4 shows another example. In forming the low-density sintered layer 11L next to the high-density sintered layer 11H, the stage 20 is normally lowered by a predetermined amount t, but here the amount of lowering is smaller than the predetermined amount t (falling down). In this state, the low-density sintered layer 11L is formed under low sintering conditions by keeping the thickness of the next powder layer 10 from becoming too thick.

In addition, as shown in FIG. 5, the sintering of the high-density sintered layer 11 </ b> H is finished in order to eliminate the step of the height δa between the surface of the powder layer 10 and the upper surface of the high-density sintered layer 11 </ b> H. After that, the powder is supplied without lowering the stage 20 (or the lowering amount of the stage 20 is set to a value smaller than the design value t), and the powder is filled in the stepped portion. After the step is lowered by forming the high-density sintered layer 11H ′, the low-density sintered layer 11L may be manufactured under low sintering conditions. If the step is large, a plurality of high-density sintered layers 11H ′ may be formed by the same procedure as described above. In this case, the low-density sintered layer 11L is formed after the high-density sintered layer 11H 'whose thickness is gradually reduced is laminated. In the figure, reference numeral 21 denotes a squeegee blade.

Further, as shown in FIG. 6 (a), the height difference δa between the surface of the powder layer 10 and the surface of the high-density sintered layer 11H is measured using the above-described height measuring probe P or the like. In this case, the low density sintered layer 11L is formed after the high density sintered layer 11H ′ is formed according to the measurement result, or the low density sintered layer 11H ′ is not formed without forming the high density sintered layer 11H ′. You may make it determine whether formation of the layer 11L is performed. When the difference δa is large, as shown in FIG. 6B, the powder is supplied without lowering the stage 20 to form the high-density sintered layer 11H ′, thereby reducing the difference δa. When the difference δa is small from the beginning, the stage 20 is lowered and the powder is supplied to form the low density sintered layer 11L.

As shown in FIG. 7, the height difference δa is detected by detecting a force F (load applied to the blade 21) F required to drive the blade 21 when the blade 21 is moved to level the powder. May be. When the load F is small, the distance between the blade 21 and the high-density sintered layer 11H is large (FIG. 7A), so that the next layer also supplies the powder without lowering the stage 20. When the load F is large, the distance between the blade 21 and the high-density sintered layer 11H is very small (FIG. 7 (b)). To supply the powder.

Incidentally, when the load applied to the blade 21 is large, the current flowing through the drive motor increases in order to follow the movement command, and conversely, when the load is small, the current that moves the blade 21 is approached as much as possible. Here, when the blade 21 passes over the previously sintered surface, it is usually subjected to resistance due to the unevenness of the surface, and this becomes a load, and if the blade 21 is separated from the surface, The above resistance is not received. Therefore, as shown in FIG. 7 (c), the current value during constant-velocity movement in which the starting current flows is monitored, and the stage 20 is lowered depending on whether this current value is larger or smaller than a threshold value determined in advance based on experimental results. Judge whether to lower or not.

Further, as shown in FIG. 8, when switching from the high-density sintered layer 11H to the low-density sintered layer 11L, the amount of lowering of the stage 20 is set to a value ts (for example, 20 μm) smaller than the design value t (for example, 50 μm). The conditions may be changed, and the powder layer 10 may be formed in this state to form the low-density sintered layer 11L under low sintering conditions.

Fig. 9 shows another example. This is because the high-density sintered layer 11H is excessively formed in the transition from the high-sintered condition for the high-density sintered layer 11H to the low-sintered condition for the low-density sintered layer 11L. The height of the layer 11H is once higher than the designed height, and then the upper surface of the high-density sintered layer 11H is cut off to the design value, and then the low-density sintered layer 11L is formed.

In each of the above examples, one sintered layer is shown in the figure as being sintered only under either high sintering conditions, low sintering conditions, or medium sintering conditions. The present invention can also be applied to a case where a high density sintered portion and a low density sintered portion are mixed in the layer. That is, as shown in FIG. 10, it can be applied to a portion where a low density sintered portion L of another sintered layer is disposed on a high density sintered portion H in a certain sintered layer. it can. In the figure, M is a medium density sintered part.

As the inorganic powder material, iron-based powders disclosed in JP-A-2001-152204 can be preferably used, and as the organic powder material, a thermoplastic resin mainly composed of nylon, ABS or the like. Can be suitably used.

It is explanatory drawing of an example of embodiment of this invention. It is explanatory drawing of another example. It is explanatory drawing of an example of other embodiment. Furthermore, it is explanatory drawing of an example of other embodiment. It is explanatory drawing of an example of another embodiment. An example of another embodiment is shown, and (a) and (b) are explanatory diagrams respectively. Furthermore, an example of another embodiment is shown, and (a), (b), and (c) are explanatory diagrams respectively. It is explanatory drawing of an example of another embodiment. It is explanatory drawing of an example of another embodiment. It is sectional drawing of another example. It is explanatory drawing of a prior art example. It is another explanatory drawing same as the above. It is another explanatory drawing same as the above.

Explanation of symbols

L Light beam 11H High-density sintered layer 11L Low-density sintered layer 11M Medium-density sintered layer 20 Stage

Claims (9)

A light beam is irradiated to a predetermined portion of the layer of the inorganic or organic powder material to sinter the powder at the corresponding portion to form a sintered layer, and a new layer of the powder material is coated on the sintered layer. A plurality of sintered layers are laminated and integrated by repeating the formation of a new sintered layer that is integrated with the underlying sintered layer by irradiating a light beam to a predetermined location and sintering the powder at the corresponding location. In producing a three-dimensional shaped article, a high density sintered layer formed under high sintering conditions and a low density sintered layer formed under low sintering conditions are selectively formed and high density sintered During the transition from high sintering conditions for bonding to low sintering conditions for low density sintered layers, medium density sintered layers irradiated with a light beam under intermediate sintering conditions of both conditions are subjected to high density sintering. A three-dimensional shape characterized by forming a low-density sintered layer on this medium-density sintered layer. Method for producing a form product. Laminate multiple layers of medium density sintered layers, and bring the sintering conditions for these medium density sintered layers closer to the low sintering conditions for the low density sintered layers for some time. The method for producing a three-dimensional shaped article according to claim 1, wherein the density is lowered. The method for producing a three-dimensional shaped article according to claim 1 or 2, wherein the sintering conditions for the medium density sintered layer are determined according to the thickness of the powder layer. A light beam is irradiated to a predetermined portion of the layer of the inorganic or organic powder material to sinter the powder at the corresponding portion to form a sintered layer, and a new layer of the powder material is coated on the sintered layer. A plurality of sintered layers are laminated and integrated by repeating the formation of a new sintered layer that is integrated with the underlying sintered layer by irradiating a light beam to a predetermined location and sintering the powder at the corresponding location. In producing a three-dimensional shaped article, a high density sintered layer formed under high sintering conditions and a low density sintered layer formed under low sintering conditions are selectively formed and high density sintered In the transition from the high sintering condition for the binder layer to the low sintering condition for the low density sintered layer, a powder layer having a thickness smaller than a predetermined value is provided on the uppermost high density sintered layer, Three-dimensional shape molding characterized by sintering this powder layer under low sintering conditions to form a low density sintered layer The method of production. A light beam is irradiated to a predetermined portion of the layer of the inorganic or organic powder material to sinter the powder at the corresponding portion to form a sintered layer, and a new layer of the powder material is coated on the sintered layer. And repeatedly forming a new sintered layer integrated with the lower sintered layer by irradiating a predetermined part with a light beam to sinter the powder in the corresponding part, and after forming the sintered layer, The required three-dimensional shape modeling in which a plurality of sintered layers are laminated and integrated by inserting the process of removing the surface part and / or unnecessary part of the model created up to this point into the process of creating a plurality of sintered layers. In manufacturing a product, a high-density sintered layer formed under high sintering conditions and a low-density sintered layer formed under low sintering conditions are selectively formed, and In the transition from sintering conditions to low sintering conditions for low density sintered layers, the high density of the top layer A powder layer having a thickness smaller than a predetermined value is provided on the bonding layer, and the powder layer is sintered under a high sintering condition to form an excessive high-density sintered layer, and then the low-density sintered layer is formed on the excessive high-density sintered layer. A method for producing a three-dimensional shaped article, characterized by forming a density sintered layer. When a powder layer having a thickness smaller than a predetermined value is provided on the uppermost high-density sintered layer, the amount of descending that determines the thickness of the powder layer of the stage on which the modeled object formed so far is set to zero is as follows. A method for producing a three-dimensional shaped article according to claim 4 or 5, wherein a powder layer is formed. When shifting from high sintering conditions for high-density sintered layers to low sintering conditions for low-density sintered layers, the next powder layer is based on the measurement results of the height of the shaped object formed so far. The method for producing a three-dimensional shaped article according to any one of claims 4 to 6, wherein a thickness of the powder and a sintering condition of the powder layer are determined. When shifting from high sintering conditions for high-density sintered layers to low sintering conditions for low-density sintered layers, the drive load of the blade that leveles the powder layer surface during the previous powder layer formation The method for producing a three-dimensional shaped article according to any one of claims 4 to 6, wherein the thickness of the next powder layer and the sintering conditions of the powder layer are determined based on the measurement result. A light beam is irradiated to a predetermined portion of the layer of the inorganic or organic powder material to sinter the powder at the corresponding portion to form a sintered layer, and a new layer of the powder material is coated on the sintered layer. And repeatedly forming a new sintered layer integrated with the lower sintered layer by irradiating a predetermined part with a light beam to sinter the powder in the corresponding part, and after forming the sintered layer, The required three-dimensional shape modeling in which a plurality of sintered layers are laminated and integrated by inserting the process of removing the surface part and / or unnecessary part of the model created up to this point into the process of creating a plurality of sintered layers. In manufacturing a product, a high-density sintered layer formed under high sintering conditions and a low-density sintered layer formed under low sintering conditions are selectively formed, and During the transition from sintering conditions to low sintering conditions for low density sintered layers, Formed to a total value or more in height, then cutting and removing until design value dense sintered layer, then, the production method of three-dimensionally shaped object, and forming a low density sintered layer.

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