JP4833673B2 - Stereolithography equipment - Google Patents

Description

  The present invention relates to an optical modeling apparatus that models a three-dimensional shape using a photocurable liquid resin and light.

  The optical modeling apparatus includes a liquid tank that stores a photocurable liquid resin, an exposure apparatus that can select whether exposure is performed or not according to a position in the liquid surface, and the liquid modeling apparatus moves up and down in the liquid tank. It has an elevator and a recoater that runs along the liquid level.

The exposure apparatus includes, for example, a light beam emitting device and an irradiation position control device that reflects the light beam toward an arbitrary position within the liquid surface. Alternatively, a light source that emits parallel light through a transmissive liquid crystal panel is provided. In either case, it is possible to select whether or not to expose the position corresponding to the position in the liquid surface.
When the liquid surface of the photocurable liquid resin is exposed, the liquid surface is cured and a cured layer is formed. The first hardened layer is shaped so as to adhere to a lifting platform that moves up and down in the liquid tank. When the lifting platform is submerged by one layer, the hardened layer fixed to the lifting platform also sinks and moves below the liquid level.
The modeling accuracy of the optical modeling apparatus is improved, and the thickness of one layer is extremely thin. Even if the cured layer is submerged by one layer, the photocurable liquid resin does not flow into the surface of the submerged cured layer due to the surface tension of the photocurable liquid resin. That is, even if the cured layer is submerged by one layer, the surface of the cured layer is not covered with the photocurable liquid resin. In the optical modeling apparatus, it is necessary to cover the surface of the cured layer with a photocurable liquid resin in preparation for the exposure of the next layer.
For this purpose, a recoater that travels along the liquid surface is prepared. When the recoater runs along the liquid surface, the surface of the cured layer that has been cured and submerged can be covered with the photocurable liquid resin.
In the optical modeling apparatus, by repeating the operations of exposing the liquid surface, settling the lifting platform, and running the recoater as one cycle, modeling an optical modeling object in which a plurality of hardened layers are stacked and integrated on the lifting platform. To do. An arbitrary three-dimensional shape can be formed by controlling the exposure area of each layer.

When the hardened layer has a large surface area, the photocurable liquid resin that should be on the front surface of the recoater may be depleted while the recoater runs along the liquid surface, and an uncoated portion may remain on the surface of the hardened layer. . Therefore, Patent Document 1 discloses a recoater in which the front surface of the recoater is inclined toward the center in the width direction with respect to the traveling direction. Inclining toward the center in the width direction with respect to the running direction means that the front of the recoater is retracted from the running direction in the vicinity of the center in the width direction relative to the vicinity of both ends in the width direction of the recoater It means that it has a V shape that opens in the direction of travel.
If the front surface of the recoater has a V shape that opens in the direction of travel, the amount of light-curable liquid resin that flows out from the side end of the recoater can be reduced, so the photocurability that should be on the front surface of the recoater. Liquid resin is hard to be depleted.

JP 2002-103458 A

In recent years, the transparency of optically shaped objects has been improved by improving the photocurable liquid resin. If the transparency of the optical model is improved, not only the three-dimensional shape exposed on the surface of the model but also the three-dimensional shape formed inside the model can be observed. It is desired.
With the improvement of transparency, the presence of bubbles has started to be observed, and in order to further improve the transparency, it has been found that it is necessary to model a model that does not contain bubbles or a model that contains less foam.
In this invention, the optical modeling apparatus which can model | mold a modeling thing with few mixing of foam is provided.

The present invention relates to a liquid tank that stores a photocurable liquid resin, an exposure apparatus that can select whether exposure is performed or not according to a position in the liquid surface, and elevation that moves up and down in the liquid tank. The present invention relates to a stereolithography apparatus including a table and a recoater that travels along a liquid surface.
In the optical modeling apparatus of the present invention, the recoater is inclined toward the side of the liquid tank with respect to the traveling direction.
Here, being inclined toward the side of the liquid tank with respect to the traveling direction means that the vicinity of the end in the width direction of the recoater is retreated from the traveling direction, contrary to the conventional recoater described above. Say. It may be uniformly retracted from one end in the width direction to the other end, or it may have advanced at the center in the width direction and retreated near both ends (closed in the running direction) (Corresponding to V-shaped). That is, the recoater is inclined from the vicinity of the center toward the end so that the vicinity of at least one end in the width direction is located behind the center in the running direction.

  If the front surface of the recoater is inclined toward the side of the liquid tank with respect to the traveling direction, if bubbles or foreign substances are mixed in the photocurable liquid resin introduced to the surface of the cured layer, the bubbles or The foreign matter is pushed to the side of the liquid tank and pushed out of the modeling area. It is possible to form an optically shaped article that is less contaminated with bubbles and foreign matter and has excellent transparency.

  The recoater may be of a type having one recoater blade, but may be of a type in which a photocurable liquid resin is stored between two recoater blades. A recoater has been developed in which the photocurable liquid resin introduced into the surface of the large-area cured layer is not depleted by running with the photocurable liquid resin stored between two recoater blades. Yes. Not only the type with one recoater blade, but also the type of recoater that stores photocurable liquid resin between two recoater blades, If it is inclined toward the direction, it is possible to form a modeled object with less transparency of bubbles and foreign matters and excellent transparency.

In the case of a recoater of a type in which a photocurable liquid resin is stored between two recoater blades, it is preferable that the two recoater blades extend in parallel in an inclined state.
It is possible to model an optically shaped object with excellent transparency.

The recoater is preferably trapezoidal when viewed from the direction orthogonal to the liquid level. Or it is preferable that the center vicinity of the width direction has advanced in the running direction with respect to the vicinity of both ends of the width direction.
In this case, even if the traveling direction of the recoater is reversed left and right, the direction in which bubbles and foreign matter are pushed is the same, and the bubbles and foreign matter are always pushed in the same direction. Foam and foreign matter pushed sideways are not returned to the modeling area.

It is also preferable that the recoater changes the inclination angle with respect to the traveling direction. That is, it is also preferable to change the inclination angle of the recoater with respect to the traveling direction as time elapses while the recoater is traveling. While traveling while traveling in an inclined state, if the inclination angle is changed to reach an angle orthogonal to the traveling direction when reaching the end of the traveling stroke, the wasteful liquid level is minimized.

When the recoater travels for the first time after settling of the hardened layer, it is also effective to travel at a low speed and then the recoater travels at a high speed in the opposite direction.
When the recoater runs for the first time after settling, if it is run at a low speed, bubbles are less likely to be mixed into the photocurable liquid resin introduced to the surface of the cured layer. However, although there are few bubbles to mix, it is not perfect. The bubbles rise above the liquid level. When the recoater travels in the opposite direction at high speed, the bubbles floating on the liquid surface are driven to the side. At this time, in order to travel at high speed, the mixed bubbles are efficiently pushed to the side. In addition, since the recoater travels at a high speed, the degree of lengthening the modeling time is also reduced.

Hereinafter, preferred embodiments of the present invention will be described.
FIG. 1 includes an overall configuration of an optical modeling apparatus 10 according to the present embodiment. The optical modeling apparatus 10 has a liquid tank 12 containing a photocurable liquid resin 11, a light source 14 for emitting laser light 13, and a spot of the laser light 13 emitted from the light source 14 accommodated in the liquid tank 12. An optical system 15 that directs the photocurable liquid resin 11 to an arbitrary position within the liquid surface 11a, an elevator 16 that moves up and down in the liquid tank 12, a drive mechanism 17 for the elevator 16, and a liquid surface 11a. Are provided with a recoater 18 that smoothes the liquid surface by moving along, a drive mechanism 19 of the recoater 18, and a control device 20. The control device 20 is connected to a three-dimensional CAD system, and inputs data describing a three-dimensional shape to be modeled from the three-dimensional CAD system. Based on the data describing the three-dimensional shape, the control device 20 controls the light source 14, the optical system 15, the elevator drive mechanism 17, and the recoater drive mechanism 19, and describes the three-dimensional shape input from the three-dimensional CAD system. A cured product (modeled product) having a three-dimensional shape described by the data is modeled.

The control device 20 processes data describing a three-dimensional shape input from the three-dimensional CAD system, and calculates a contour line for each cross section. Hereinafter, the first and nth cross sections are formed from the bottom to the top of the modeled object. The control device 20 controls the light source 14, the optical system 15, the elevator drive mechanism 17 and the recoater drive mechanism 19 as follows.
(1) The elevator 16 is submerged to a depth of one hardened layer from the liquid surface 11a.
(2) The light source 14 and the optical system 15 are controlled on the basis of the contour line data of the i-th cross section, the liquid surface within the contour is exposed, and the liquid surface outside the contour is not exposed.
(3) The elevator 16 is further submerged by a depth corresponding to one hardened layer.
(4) The recoater 18 is run along the liquid level.
(5) The above controls (2) to (4) are repeatedly executed. When (2) is executed for the first time, i = 1 is set, and each time (2) is repeated, i is increased by 1. When i = n−1 and (2) to (4) are performed, i = (2) is executed as n.
When the above processing is performed, a modeled object having a three-dimensional shape specified by the three-dimensional CAD system is formed in the liquid tank 12.

(First embodiment)
FIG. 2 is a plan view of the recoater 18 and the liquid tank 12, and the recoater 18 includes one thin recoater blade 21. The recoater blade 21 extends perpendicularly to the liquid surface 11 a and is inclined with respect to the traveling direction R toward the side 12 a of the liquid tank 12. When the recoater blade 21 travels in the R direction, bubbles and foreign substances are pushed toward the side 12a of the liquid tank 12 on the front surface thereof as indicated by an arrow 22a. There is a slight gap between one end 21a in the width direction of the recoater blade 21 and the side 12a of the liquid tank 12, and bubbles and foreign substances pushed to the side 12a remain in the gap. Even if the recoater blade 21 travels in the L direction, bubbles and foreign matter pushed to the side 12a are not returned to the central modeling area.
At the same time, the recoater blade 21 is inclined toward the side 12 b of the liquid tank 12 with respect to the traveling direction L. When the recoater blade 21 travels in the L direction, bubbles and foreign substances are pushed toward the side 12b of the liquid tank 12 on the front surface thereof as indicated by an arrow 22b. There is a slight gap between one end 21b in the width direction of the recoater blade 21 and the side 12b of the liquid tank 12, and bubbles and foreign substances pushed to the side 12b remain in the gap. Even if the recoater blade 21 travels in the R direction, bubbles and foreign matter pushed to the side 12b are not returned to the central modeling area.
Using a recoater that is inclined toward the side of the liquid tank with respect to the traveling direction, foam and foreign substances are removed from the photocurable liquid resin introduced to the surface of the cured layer, and a model with excellent transparency is formed. can do.

  In the case of this recoater 18, it is preferable that the recoater reciprocates once between exposures. For example, when traveling for the first time after settling of the hardened layer, it travels in the R direction, and then travels in the L direction for the next exposure. In this case, when traveling in the R direction for the first time, a photocurable liquid resin is introduced into the surface of the cured layer, and when traveling in the L direction, bubbles and foreign substances are pushed laterally from the exposure area. In this case, when traveling first in the R direction and introducing the photocurable liquid resin to the surface of the cured layer, it travels at a low speed, and then when traveling in the L direction and pushes bubbles and foreign matter to the side, the speed is high. It is preferable to run on. By doing so, it is possible to form a model with few bubbles and foreign matters and excellent transparency.

(Second embodiment)
3 and 4 show a second embodiment of the recoater 18. The recoater 18 of the second embodiment includes two recoater blades 24 and 26, stores a photocurable liquid resin in the gap between the two, and a cured layer in a state where a large amount of the photocurable liquid resin is stored. Drive over the road. Even when the photocurable liquid resin is introduced into the surface of the cured layer having a large area, the photocurable liquid resin is not exhausted.
As shown in FIG. 4, a horizontal blade 28 that moves up and down is installed between the two recoater blades 24 and 26, and the lower surface of the horizontal blade 28 is hydrophilic to the photocurable liquid resin. is there. When the horizontal blade 28 is lowered until it comes into contact with the liquid surface 11a, and then raised, the photocurable liquid resin is stored in the gap between the two recoater blades 24 and 26.
Each of the recoater blades 24 and 26 extends perpendicularly to the liquid surface 11 a and is inclined toward the side 12 a of the liquid tank 12 with respect to the traveling direction R. When the recoater blades 24 and 26 travel in the R direction, bubbles and foreign substances are pushed toward the side 12a of the liquid tank 12 on the front surface thereof as indicated by arrows 28a and 30a. There is a slight gap between one end of the recoater blades 24 and 26 in the width direction and the side 12a of the liquid tank 12, and bubbles and foreign substances pushed to the side 12a remain in the gap. Even if the recoater blades 24 and 26 travel in the L direction, bubbles and foreign substances pushed to the side 12a are not returned to the central modeling area.
At the same time, the recoater blades 24, 26 are inclined toward the side 12 b of the liquid tank 12 with respect to the traveling direction L. When the recoater blades 24 and 26 travel in the L direction, bubbles and foreign substances are pushed toward the side 12b of the liquid tank 12 on the front surface thereof as indicated by arrows 28b and 30b. There is a slight gap between one end of the recoater blades 24 and 26 in the width direction and the side 12b of the liquid tank 12, and bubbles and foreign substances pushed to the side 12b remain in the gap. Even if the recoater blades 24 and 26 travel in the R direction, bubbles and foreign matters pushed to the side 12b are not returned to the central modeling area.
Since this recoater is also inclined toward the side of the liquid tank relative to the running direction, bubbles and foreign substances are removed from the photocurable liquid resin introduced to the surface of the cured layer, and a model with excellent transparency Can be shaped.

When the two recoater blades 24 and 26 are provided, the functions of the recoater blades 24 and 26 are different. When the recoater blades 24 and 26 travel in the R direction, mainly the front surface of the recoater blade 26 introduces a photocurable liquid resin into the surface of the cured layer, and the recoater blade 24 introduces the introduced photocurable liquid. Smooth the liquid surface of the resin. When the recoater blades 24 and 26 travel in the L direction, the photocurable liquid resin in which the front surface of the recoater blade 24 mainly introduces a photocurable liquid resin into the surface of the cured layer and the recoater blade 26 is introduced. Smooth the liquid surface of the resin.
In any case, since the recoater blades 24 and 26 are inclined toward the side of the liquid tank with respect to the traveling direction, bubbles and foreign substances are removed from the photocurable liquid resin introduced to the surface of the cured layer. Therefore, it is possible to model a model with excellent transparency.

  The recoater blades 24 and 26 were tilted by 2 degrees (θ = 2 ° in FIG. 3) with respect to the traveling direction to form a model having a horizontal plane of 50 × 50 mm and a thickness of 5 mm. The thickness of one layer was 0.1 mm, and 50 lamination cycles were repeated. For comparison, an experiment was performed under the same conditions using a recoater with θ = 0 °. In the comparative example, many bubbles were observed in a portion close to a square side, but when formed using a recoater with θ = 2 °, bubbles that could be observed with the naked eye could be eliminated.

  FIG. 5 shows another embodiment with two recoater blades. In this case, the space surrounded by the two recoater blades and the liquid level is reduced by a pump. Then, the liquid level rises at the interval between the two recoater blades, and the photocurable liquid resin can be stored at the interval between the two recoater blades. Even with this type of recoater, it is possible to prevent bubbles and foreign matters from being mixed into the modeled object by inclining with respect to the traveling direction.

FIG. 6 shows an example of a recoater having a trapezoidal shape when observed from a direction perpendicular to the liquid surface. In this case, even if the vehicle travels in the L direction or the R direction, bubbles and foreign matter are pushed to the side 12a. Pressed bubbles and foreign objects are not returned to the modeling area.
7 and 8 show a recoater in which the vicinity of the center in the width direction advances in the traveling direction with respect to the vicinity of both ends in the width direction of the recoater. In this case, even if the traveling direction of the recoater is reversed left and right, the bubbles and foreign matter present in the region above the broken line are pushed to the side 12a, and the bubbles present in the region below the broken line. Or foreign matter is pushed to the side 12b. Pressed bubbles and foreign objects are not returned to the modeling area.
As shown in FIGS. 6 to 8, a recoater having a relatively wide surface in contact with the liquid surface may be used. On the other hand, as shown in FIGS. 9 to 11, two recoater blades that store a photocurable liquid resin between them may be used. Even if it does in this way, a modeling thing with few mixing of a bubble can be modeled.

  FIG. 12 shows a recoater that changes the inclination angle with respect to the traveling direction. FIG. 12 shows changes in the inclination angle when traveling in the R direction, and the inclination angle θ is zero as shown at t1 before the start of traveling. When traveling is started, only the lower end side travels until time t2, and the recoater tilts to θ. When tilted to θ at time t2, the entire recoater thereafter translates and travels in a state tilted by θ. When the lower end of the recoater arrives at the stroke end at time t4, the lower end stops, but the upper end continues to move further, and stops at θ = 0 ° at time t5. In this case, the liquid level in the area shown by the hatch becomes unnecessary, and the liquid tank can be miniaturized.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

The figure which shows the whole structure of the optical modeling apparatus of an Example. The top view of the recoater of 1st Example is shown. The top view of the recoater of 2nd Example is shown. The partial perspective view of the recoater of 2nd Example is shown. The partial perspective view of the recoater of the modification of 2nd Example is shown. The top view of the recoater of another example is shown. Furthermore, the top view of the recoater of another example is shown. Furthermore, the top view of the recoater of another example is shown. The top view of the recoater of the modification of FIG. 7 is shown. The top view of the recoater of the modification of FIG. 8 is shown. The top view of the recoater of the modification of FIG. 9 is shown. The operation of the recoater that changes the tilt angle is shown over time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Stereolithography apparatus 11: Photocurable liquid resin 12: Liquid tank 12a: One side 12b: The other side 13: Laser beam 14: Light source 15: Optical system 16: Lifting table 17: Lifting table drive device 18 : Recoater 19: Recoater drive device 20: Control device 21: Recoater blade 24: Recoater blade 26: Recoater blade L, R: Travel direction θ: Inclination angle

Claims (7)

A liquid tank for storing a photocurable liquid resin;
An exposure apparatus capable of selecting whether to perform exposure or not according to a position in the liquid surface;
A lifting platform that moves up and down in the liquid tank;
It has a recoater that runs along the liquid surface,
The stereolithography apparatus, wherein the recoater is inclined from the vicinity of the center toward the end so that the vicinity of at least one end in the width direction is located behind the center in the running direction .   2. The stereolithography apparatus according to claim 1, wherein the recoater includes two recoater blades for storing a photocurable liquid resin therebetween.   The stereolithography apparatus according to claim 2, wherein the two recoater blades are parallel to each other.   The stereolithography apparatus according to claim 1, wherein the recoater is trapezoidal when viewed from a direction perpendicular to the liquid surface.   The stereolithography apparatus according to claim 1, wherein the recoater has advanced in the running direction in the vicinity of the center in the width direction with respect to the vicinity of both ends in the width direction. The stereolithography apparatus according to claim 1, wherein an inclination angle of the recoater itself with respect to a traveling direction is changed as time elapses while the recoater is traveling .   The stereolithography apparatus according to claim 1, wherein the recoater travels at a low speed when traveling for the first time after settling of the hardened layer, and then travels at a high speed in the opposite direction.

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