JP4820181B2 - 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.

  The photocurable liquid resin has viscosity, and it takes time to smooth the liquid surface. Therefore, a technique for promoting smoothing of the liquid surface by applying ultrasonic vibration to the photocurable liquid resin has been developed, and is disclosed in Patent Document 1. In the technique of Patent Document 1, an ultrasonic generator is attached to the outer surface of the liquid tank.

JP-A-5-278122

In recent years, the transparency of optically shaped objects has been improved by improving the photocurable liquid resin. When the transparency of the optically shaped object is improved, not only the three-dimensional shape exposed on the surface of the shaped object but also the three-dimensional shape formed inside the object can be observed, and further transparency is desired. ing.
It has been found that in order to improve the transparency, it is necessary to form a model that does not contain bubbles or a model that contains less bubbles in order to improve the transparency. As described in JP-A-5-278122, even if an ultrasonic generator is attached to the outer surface of the liquid tank and ultrasonic vibration is applied to the photocurable liquid resin, the bubbles do not disappear.
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 stereolithography apparatus of the present invention, the recoater includes defoaming means for sucking and removing the bubbles that have floated on the liquid surface .

  When the recoater travels along the liquid surface, the uncured photocurable liquid resin is introduced into the surface of the cured layer that has been cured and submerged first. At this time, bubbles are mixed in the uncured photocurable liquid resin introduced on the surface of the cured layer. The recoater of the present invention is provided with a defoaming means, and erases bubbles mixed in the uncured photocurable liquid resin introduced on the surface of the cured layer. It is possible to form a modeled object with less bubbles and excellent transparency.

Various antifoaming means may be used in combination with the antifoaming means for sucking and removing the bubbles floating on the liquid surface . For example, a member that vibrates itself can be used in combination . When the bubble contacts the vibrating member, the bubble disappears. Or you may utilize together and use the member which heats the bubble which floated on the liquid level. When heat is applied to the foam, the foam disappears. Alternatively, a member that contacts the bubbles and mechanically breaks the bubbles, for example, a member such as a needle may be used in combination .

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 shows the vicinity of the recoater 18 in an enlarged manner, and FIG. 3 shows a cross section taken along line III-III. In FIG. 2, for the sake of clarity of illustration, a part is broken and shown.
The recoater 18 includes a main body 34 and wheels 32 and 32, and travels along a rail 30 fixed to the outside of the liquid tank 12. The rail 30 extends horizontally.
A pair of recoater blades 36 and 38 (see also FIG. 3) are fixed to both sides of the main body 34 in the traveling direction. The lower ends of the recoater blades 36 and 38 are set to a height that makes contact with the liquid surface 11a. When the recoater 18 travels along the rail 30, the lower ends of the recoater blades 36 and 38 sweep the liquid surface 11a. A horizontal plate 40 is installed in a range between the pair of recoater blades 36 and 38 below the main body 34. A portion 42 of the horizontal plate 40 passes through the main body 34 and reaches the upper portion of the main body 34, and is connected to the vertical movement mechanism 44. The horizontal plate 40 moves up and down while being kept horizontal by the vertical movement mechanism 44. The lower surface of the horizontal plate 40 is hydrophilic to the photocurable liquid resin. When the horizontal plate 40 is lowered until it comes into contact with the liquid surface 11 a and then lifted, the photocurable liquid resin is stored in the gap between the two recoater blades 36 and 38. The recoater 18 travels above the cured layer in a state where a large amount of the photocurable liquid resin is stored, so that the photocurable liquid resin is introduced even when the photocurable liquid resin is introduced into the surface of the large area cured layer. The resin will not be depleted.
A diaphragm 48 is disposed so as to cover the recoater body 34. The diaphragm 48 is connected to the recoater main body 34 by a connecting tool (not shown), and travels on the liquid surface together with the recoater main body 34. As well shown in FIG. 3, the diaphragm 48 includes a horizontal portion and a pair of vertical portions extending downward from both left and right ends thereof, and the height of the lower ends of the pair of vertical portions is a pair of recoaters. It is equal to the height of the lower end of the blades 36 and 38. An ultrasonic transducer 46 is attached to the diaphragm 48, and the diaphragm 48 vibrates ultrasonically. The coupling for connecting the diaphragm 48 to the recoater body 34 is provided with a structure for cutting off the vibration, and the recoater body 34, the recoater blades 36 and 38, and the horizontal plate 40 do not vibrate.

  FIG. 3 shows a state in which the uncured photocurable liquid tree 11 is introduced to the surface of the submerged cured layer 50 by the recoater 18. FIG. 3 shows a case where the recoater blade 36 is running in the front direction and the recoater blade 38 is running in the rear direction. When the recoater 18 travels, the uncured photocurable liquid resin 11 is introduced to the surface of the cured layer 50 at a position immediately after the front surface of the recoater blade 36. At this time, some bubbles are involved. The bubbles eventually rise above the liquid level. Some bubbles are captured by the rear-side recoater blade 38 and trapped at the boundary between the recoater blade 38 and the horizontal plate 40. It is possible to prevent bubbles from entering the uncured photocurable liquid resin 11 introduced on the surface of the cured layer 50. Bubbles not captured by the recoater blade 38 come into contact with the lower end of the vertical portion on the rear side of the diaphragm 48. The lower end of the vertical part on the rear side of the vibration plate 48 vibrates, and the foam that touches it repels and disappears. In this way, bubbles are removed from the uncured photocurable liquid tree 11 introduced on the surface of the cured layer 50.

  As a result of modeling with this recoater, no bubbles were present in the modeled object as long as it was observed with the naked eye. On the other hand, when the operation of the ultrasonic transducer 46 was stopped and modeling was performed, bubbles were observed in the modeled object. In particular, many bubbles were observed near the contour of the model. It was confirmed that the defoaming means by the ultrasonic vibrator 46 and the diaphragm 48 functioned effectively, and by defoaming, it was possible to form a model with less foam mixing and excellent transparency.

FIG. 4 shows a recoater provided with another defoaming means, which includes hot wires 54 and 56. The hot wires 54 and 56 are symmetrically arranged in the front and rear directions of the recoater, and the height thereof is slightly higher than the height of the lower ends of the pair of recoater blades 36 and 38. That is, the hot wires 54 and 56 move slightly above the liquid level. The bubbles that rise and rise on the liquid surface come into contact with the heat rays 54 and 56.
When this recoater is used, the bubbles not captured by the recoater blade on the rear side in the traveling direction come into contact with the heat rays on the rear side in the traveling direction, as described with reference to FIG. Bubbles in contact with the heat rays are heated and repelled, and the bubbles disappear. In this way, bubbles are removed from the uncured photocurable liquid tree 11 introduced to the surface of the cured layer 50.
You may make it transmit the vibration of an ultrasonic transducer | vibrator to the heat wires 54 and 56. FIG. Bubbles are reliably removed by vibration and heat.

FIG. 5 shows a recoater provided with another defoaming means, and includes needle groups 58 and 60. The needle groups 58 and 60 are arranged symmetrically in the front and rear directions in the traveling direction of the recoater, and the height thereof is slightly higher than the height of the lower ends of the pair of recoater blades 36 and 38. That is, the needle groups 58 and 60 move slightly above the liquid level. The bubbles that rise and rise on the liquid surface come into contact with the needle groups 58 and 60.
When this recoater is used, as described with reference to FIG. 3, bubbles not captured by the recoater blade on the rear side in the traveling direction come into contact with the needle group on the rear side in the traveling direction. The foam that contacts the needle group is mechanically destroyed and the foam disappears. In this way, bubbles are removed from the uncured photocurable liquid tree 11 introduced to the surface of the cured layer 50.

FIG. 6 shows a recoater provided with another defoaming means, which includes suction nozzles 70 and 72. The suction nozzles 70 and 72 are symmetrically arranged in the front and rear directions of the recoater, and the height of the suction port is slightly higher than the height of the lower ends of the pair of recoater blades 36 and 38. That is, the suction ports of the suction nozzles 70 and 72 move slightly above the liquid level. Bubbles that rise and rise on the liquid surface are sucked into the suction port and removed from the liquid surface. The suction nozzles 70 and 72 are connected to a pump that generates a negative pressure, and the sucked liquid resin is returned to the liquid tank 11.
When this recoater is used, as described with reference to FIG. 3, bubbles not captured by the recoater blade on the rear side in the running direction are sucked by the suction nozzle on the rear side in the running direction and removed from the liquid level. The In this way, bubbles are removed from the uncured photocurable liquid tree 11 introduced to the surface of the cured layer 50.

  Since any of the above recoaters is provided with a defoaming means, the foam is removed from the photocurable liquid resin introduced to the surface of the cured layer, and a model with excellent transparency can be formed.

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 perspective view of the recoater of 1st Example is shown. Sectional drawing of the recoater of 1st Example is shown. The perspective view of the recoater of 2nd Example is shown. The perspective view of the recoater of 3rd Example is shown. The perspective view of the recoater of 3rd Example is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10: Stereolithography apparatus 11: Photocurable liquid resin 12: Liquid tank 13: Laser beam 14: Light source 15: Optical system 16: Lifting stand 17: Lifting stand drive device 18: Recoater 19: Recoater drive device 20: Control device 36 , 38: Recoater blade 46: Ultrasonic vibrator 48: Diaphragm 54, 56: Hot wire 58, 60: Needle group 70, 72: Suction nozzle

Claims (1)

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,
An optical modeling apparatus, wherein the recoater includes defoaming means that sucks and removes the bubbles floating on the liquid surface .

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