JPH07137145A - Method and apparatus for optical formation - Google Patents

Abstract

PURPOSE:To prepare for a following layer in a short period, or obviate the necessity of flattening means and also render the structure simple by controlling the placement of a movable base plate and supply of photo-setting resin, and thus making the position of a free liquid level constant, and giving vibration to the movable base plate for conducting the perfect covering and flattening of resin. CONSTITUTION:A movable base plate 3 is maintained at the depth of, e.g. 0.1mm from the liquid level 11 of resin. Beam light 4 is scanned on the basis of slice-frigure data for exposure. In this manner, the first layer 5 of a thin plate solidified layer is fixed on the movable base plate 3. In the next place, photo-setting resin 2 is supplied from photo-setting resin supplying means 9 to such an extent that liquid level overflows from the resin bath 1, and then the movable base plate 3 is lowered for one layer of the thin plate solidified layer. Then, when the movable base plate 3 is given vibration by an actuator 8, the first layer 5 is completely covered with photo-setting resin 2, and further flattening of the photo-setting resin layer 2 can be achieved. After that, beam light 4 is exposed in the same manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stereolithography method, and more particularly to a stereolithography method by a free liquid surface method and an apparatus therefor.

[0002]

2. Description of the Related Art In recent years, industrial products have been required to have a design with many curved surfaces, and the mounting density of parts has become extremely high. For this reason, techniques for handling three-dimensional shapes by computers have been developed, and designs using three-dimensional CAD systems are becoming popular. Along with this, numerical control (NC) milling that directly uses CAD data is used for processing a three-dimensional object model. However, in reality, it is difficult to process a completely three-dimensional shape, and in practice, only a relief engraving can be produced. In particular, it is virtually impossible to accurately machine an internal structure with an NC machine tool.

As one of the methods for solving the above problems, there is a photoreactive molding method using a photocurable resin. This is described in detail in the article by Marutani, for example, in "Laser Research" (Vol. 18, No. 7, pp. 448 to 455). Following Marutani, a photoreactive molding method using a photocurable resin is referred to as a stereolithography method.

Formation of a three-dimensional object model by the stereolithography method is generally performed as follows. First, a numerical model (CAD data or three-dimensional measurement data) defined on a computer is cut along a horizontal plane at equal intervals in the height direction to create a slice graphic data group. Next, these data are taken out from the lower end, and the photocurable resin is irradiated and scanned with a light beam based on the shape. The irradiated portion undergoes a polycondensation reaction to solidify. The irradiation light is absorbed and attenuated in the resin, and solidification occurs only on the surface of the resin, so that a thin plate solidified layer is formed. After that, an uncured resin layer having a predetermined thickness is overlaid thereon, and the next slice graphic data is exposed and solidified. This process is gradually repeated until the upper end, and by laminating thin plate-like solidified layers, an arbitrary three-dimensional object model is formed. The upper and lower layers are firmly bonded to each other during the curing reaction, and as a result, the whole becomes a solid three-dimensional model of plastic.

As one of the methods for laminating an uncured resin layer having a predetermined thickness on a thin plate-like solidified layer, there is a free liquid level method in which the surface of a resin liquid to be irradiated with light is a free liquid surface by the action of gravity.
FIG. 2 is an explanatory diagram of the free liquid level method. Reference numeral 1 denotes a resin tank for storing a photocurable resin 2 which is, for example, a radical polymerization type acrylate resin. Reference numeral 3 denotes a movable base plate which moves in the vertical direction, on which a three-dimensional object model is formed. Reference numeral 4 denotes a beam light from, for example, a He-Cd laser device, which is scanned by an optical system using a galvanometer (not shown) controlled based on the above-mentioned slice figure data.

Lamination of the thin plate solidified layer by the free liquid level method is performed by the following procedure. First, the movable base plate 3 is immersed in a resin and moved up and down, and is held at a predetermined depth d of the thin plate-like solidified layer from the liquid surface 11 of the resin, for example, at a depth of about 0.1 mm. Then, the light beam 4 is exposed while scanning based on the slice graphic data. By this step, the first layer 5 of the thin plate solidified layer is formed, and the movable base plate 3
Stuck to.

Next, the distance from the upper surface of the first layer 5 of the thin plate-like solidified layer to the free liquid surface 11 of the photocurable resin 2 is set to be equal to the thickness of one layer of the thin plate-like solidified layer described above. The base plate 3 is moved downward and held. Thereby, the uncured resin layer 6 having a predetermined thickness is formed on the first layer of the thin plate solidified layer 5. The volume occupied by the photocurable resin 2 in the liquid of the support mechanism 31 of the movable base plate 3 changes each time the movable base plate 3 moves. Therefore, in consideration of this condition, it is necessary to control the movable base plate 3 to be in the above state. Then, the next slice graphic data is exposed and solidified. A desired three-dimensional object model is formed by repeating the above steps.

[0008]

As described above, the free liquid level method is a simple method, but before the exposure and solidification, the uncured resin layer 6 is completely and completely formed on the underlying solidified layer. It is necessary to cover flatly so as to have a constant layer thickness. However, since the photo-curable resin 2 has a constant surface tension, the photo-curable resin 2 is solidified by simply controlling the movable base plate 3 as described above and moving and holding the movable base plate 3 downward by a predetermined depth. It cannot be completely covered and the uncured resin layer 6 cannot be formed. Therefore, conventionally, after the movable base plate 3 is submerged to a predetermined depth or more and the photocurable resin 2 completely covers the solidified layer, the support mechanism 31 of the movable base plate 3 is occupied in the liquid by the liquid. The uncured resin layer 6 is formed by moving the movable base plate 3 upward to a predetermined position and holding it while sufficiently considering the volume.

Since the photocurable resin 2 has a certain viscosity depending on the type of resin, the uncured resin layer 6 does not become flat just by completely covering the solidified layer. Therefore, conventionally, after the movable base plate 3 is held as described above, the uncured resin layer 6 is swept and flattened by, for example, brush-shaped sweeping means before exposure and solidification. Or JP-A-5
As disclosed in -96632, the photocurable resin 2 is subjected to ultrasonic vibration to enhance the fluidity, and the time required for flattening the photocurable resin 2 is shortened. However, in the method of applying ultrasonic vibration to the photocurable resin 2, in the case of a multi-tube whose model to be formed is a structure composed of 100 and 101 as shown in FIG. 3, the ultrasonic vibration is transmitted to the inner tube portion 101. Since it is difficult, it takes time to flatten. As described above, in the conventional stereolithography by the free liquid level method, it takes time to prepare the thin plate solidified layer 5 for one layer after preparation, and a complicated control mechanism is required. Since it is necessary, it has a drawback that the device structure is complicated.

Therefore, the present invention has been made in view of the above circumstances, and an object thereof is to provide a movable base plate simply in a predetermined thin plate-like solidified layer having a thickness of one layer in a stereolithography method by the free liquid surface method and its apparatus. By only lowering the amount, an uncured resin layer 6 having a predetermined thickness is formed on the solidified layer,
An object of the present invention is to provide an optical modeling method and its apparatus that can realize the flattening without using the sweeping means or the means for applying ultrasonic vibration to the photocurable resin 2.

[0011]

In order to achieve the above object, the present invention provides a movable base plate which accommodates a photocurable resin in a resin tank and moves in the vertical direction from a free liquid surface of the photocurable resin. After moving a fixed distance downward, exposing and solidifying with the beam of light, repeating the step of sequentially moving the movable base plate downward by a fixed distance and exposing / fixing and fixing with the beam of light to finally obtain a desired three-dimensional object. In the stereolithography method for obtaining a model, the position of the free liquid surface is controlled by controlling the supply of the photocurable resin before the movement of the movable base plate, and the movable base plate is vibrated to completely cover and flatten the resin. Make up.

Further, the photocurable resin is housed in a resin tank, and the movable base plate which moves in the vertical direction is moved below the free liquid surface of the photocurable resin by a certain distance, and after exposure and solidification by beam light. In a stereolithography apparatus that sequentially obtains a desired three-dimensional object model by repeating a process of sequentially moving the movable base plate downward by a predetermined distance and exposing and solidifying and fixing with a light beam, the position of the movable base plate and photocuring Installed on the movable base plate for controlling the supply of the functional resin to keep the position of the free liquid surface constant and for vibrating the movable base plate to completely cover and flatten the resin. Vibration supply means.

[0013]

By vibrating the vibrating means installed on the movable base plate, the solidified layer formed on the movable base plate also vibrates. Therefore, by lowering the movable base plate by one thickness of a predetermined thin plate solidified layer and vibrating the vibrating means at a predetermined frequency, the photocurable resin is completely covered with a predetermined thickness on the solidified layer. Further, since the vibration of the solidified layer acts as a pressure on the photo-curable resin completely covering the solidified layer, the flattening is realized by controlling the frequency of the vibrating means. As described above, an uncured resin layer having a predetermined thickness is formed on the solidified layer. Since the position of the free liquid surface is constant, the movable base plate is simply the thickness of one predetermined thin plate solidified layer without considering the volume occupied by the supporting mechanism in the photocurable resin liquid. It is held in place simply by lowering it.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the embodiments shown in the drawings. FIG. 1 is a schematic explanatory diagram illustrating an optical modeling apparatus that is an embodiment of the present invention. Reference numeral 1 denotes a resin tank for storing a photocurable resin 2 which is, for example, a radical polymerization type acrylate resin. Reference numeral 3 denotes a movable base plate which moves in the vertical direction, on which a three-dimensional object model is formed. Reference numeral 4 denotes a beam light from, for example, a He-Cd laser device, which is scanned by an optical system using a galvanometer (not shown) controlled based on the above-mentioned slice figure data. An actuator 8 is attached to the movable base plate 3 to give vibration. Further, 9 is a photocurable resin supply means for keeping the liquid surface 11 of the photocurable resin 2 in the resin tank 1 at a position where it overflows at all times, and 10 is a supply resin tank.

The lamination of the thin plate solidified layers in this embodiment is carried out by the following procedure. First, the movable base plate 3 is dipped and penetrated in a resin and moved up and down, and is held at a predetermined depth of the thin plate solidified layer from the liquid surface 11 of the resin, for example, a position of about 0.1 mm. Then, the light beam 4 is exposed while scanning based on the slice graphic data. By this step, the first layer 5 of the thin plate solidified layer is formed, and the movable base plate 3
Stuck to. In the drawing, for the sake of explanation, the first thin solidified layer
After the layer 5 is formed, the movable base plate 3 is further moved downward by the distance d.

Next, the photocurable resin supplying means 9 supplies the photocurable resin 2 until the liquid surface of the photocurable resin 2 in the resin tank 1 overflows. Then, the movable base plate 3 is lowered by the thickness of one predetermined thin plate solidified layer. Since the liquid surface of the photocurable resin 2 is at a fixed position before the movable base plate 3 is lowered, the volume occupied by the photocurable resin 2 of the support mechanism 31 of the movable base plate 3 in the liquid is changed with the movement of the movable base plate 3 each time. Even if it changes, the movable base plate 3 is simply lowered by one thickness of a predetermined thin plate-like solidified layer to reach the free liquid surface 11 of the photocurable resin 2 from the upper surface of the first layer 5 of the thin plate-like solidified layer. The distance d is set to be equal to the thickness of one layer of the thin plate solidified layer described above.

After moving the movable base plate 3, the actuator 8 is operated to give vibration to the movable base plate 3. Since the first layer 5 of the thin plate-like solidified layer is fixed to the movable base plate 3, the first layer 5 of the thin plate-like solidified layer is inevitable.
Also vibrates at the same time. If the vibration amplitude is set to be approximately the same as the thickness of one layer of the thin plate solidified layer, the first layer 5 of the thin plate solidified layer is completely covered with the photocurable resin 2. Further, since the vibration of the solidified layer acts as a pressure on the photocurable resin 2 that completely covers the solidified layer, the flattening can be realized by controlling the frequency of the vibrating means. Then, the vibration is stopped and the beam light 4 is exposed while scanning based on the slice figure data. A desired three-dimensional object model is formed by repeating the above steps.

In the present invention, since the thin plate-like solidified layer serving as a three-dimensional object model is vibrated directly through the movable base plate 3, for example, even if the model to be formed is a multiple tube as shown in FIG. Vibration can be easily transmitted to 101,
The first layer 5 of the thin plate-like solidified layer forming the inner tube portion 101 is completely covered with the photocurable resin 2, and flattening can be achieved in a short time.

[0019]

As described above, according to the stereolithography apparatus of the present invention, the vibrating means installed on the movable base plate vibrates, so that the solidified layer formed on the movable base plate also vibrates. Therefore, by lowering the movable base plate by one layer of a predetermined thin plate solidified layer and vibrating the vibrating means at a predetermined frequency, the photocurable resin can be completely covered with a predetermined thickness on the solidified layer. it can. Further, since the vibration of the solidified layer acts as a pressure on the photocurable resin completely covering the solidified layer, it is possible to realize the flattening by controlling the frequency of the vibrating means. An uncured resin layer having a predetermined thickness is formed on the solidified layer. Therefore, after forming one thin plate-like solidified layer, the preparation process for the next layer can be realized in a short time, and a separate flattening means is not required, so that the device structure can be simplified. In addition, since the photocurable resin is supplied to the resin tank by the photocurable resin supply means so that the position of the free liquid surface is constant, the movable base plate has a volume occupied by the photocurable resin of the supporting mechanism in the liquid. It is possible to hold the film in a predetermined position by simply lowering the thickness of the predetermined thin plate solidified layer by one layer without considering the above.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram illustrating an optical modeling apparatus that is an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a free liquid level method.

FIG. 3 is an explanatory diagram of a stereolithography method in a three-dimensional object model of multiple tubes.

[Simple explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Resin tank 2 Photocurable resin 3 Movable base plate 31 Support mechanism of the movable base plate 3 4 Beam light 5 1st layer of plate-like solidified layer 6 Unhardened resin layer 8 Actuator 9 Photocurable resin supply means 10 Supplying resin tank 11 Free liquid level

Claims (2)

[Claims] 1. A resin tank containing a photocurable resin, and a movable base plate that moves in the vertical direction is moved downward by a certain distance from the free liquid surface of the photocurable resin, and after exposure and solidification by beam light. In the stereolithography method in which the step of sequentially moving the movable base plate downward by a predetermined distance and the exposure / solidification / fixation by the beam light are repeated to finally obtain a desired three-dimensional object model, the position of the movable base plate and the photocuring are set. Molding method, characterized in that the position of the free liquid surface is controlled by controlling the supply of the functional resin, and the movable base plate is vibrated to completely cover and flatten the resin. 2. A photocurable resin is housed in a resin tank, and a movable base plate which moves vertically is moved below a free liquid surface of the photocurable resin by a certain distance, and after exposure and solidification by beam light. In a stereolithography apparatus that sequentially obtains a desired three-dimensional object model by repeating a process of sequentially moving the movable base plate downward by a predetermined distance and exposing and solidifying and fixing with a light beam, the position of the movable base plate and photocuring Installed on the movable base plate for controlling the supply of the functional resin to keep the position of the free liquid surface constant and for vibrating the movable base plate to completely cover and flatten the resin. A stereolithography apparatus including a vibration supply unit.