JPH0224123A - Optical shaping method - Google Patents

Abstract

PURPOSE:To mitigate shrinkage stress at the time of cure by dividing a curing process into two stages. CONSTITUTION:Photosetting resin is cured by irradiation with light by intermitting scanning light flux 27 or imparting variety to strength so that uncured resin is left behind partly, in the first curing process. With this construction, shrinkage stress due to cure is dispersed, absorbed by an uncured part and becomes a cured solid where the shrinkage stress hardly occurs as a whole. In the second curing process, the photosetting resin remaining uncured is cured by applying light further to a primary cured body obtained in the first curing process. Even in the second curing process, the shrinkage stress hardly occurs so long as the uncured resin exists on the circumference at the time of spreading of cure in a sphere where the cure progresses. The shrinkage stress is generated in an extremely short period of time at the last stage of the cure and shrinkage stress itself becomes extremely little.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical modeling method for producing a cured product in a desired shape by irradiating a photocurable resin with light, and in particular, it relates to an optical modeling method that produces a cured product in a desired shape by irradiating a photocurable resin with light. This invention relates to an optical modeling method in which shrinkage stress during curing is alleviated by separating the parts.

[Prior art] A light beam is irradiated onto a photocurable fluid material such as a photocurable resin,
The irradiated part is cured, and this cured part is made to continue in the horizontal direction, and a photocurable fluid material is further supplied above it and cured in the same manner, thereby making the cured body continuous in the vertical direction. An optical modeling method for manufacturing a cured body of a desired shape by repeating the process is disclosed in Japanese Patent Application Laid-Open No. 60-2475.
No. 15, No. 62-35966, No. 62-101408, etc. In addition, light is irradiated through a modeling mask having a slit corresponding to one cross section of the cured product in the desired shape to cure the material, and then an uncured photocurable fluid material is placed on the cured layer and the material is used for modeling. There is also an optical modeling method in which a cured product of the desired shape is manufactured by replacing the mask with one that has a slit corresponding to one cross section adjacent to the height direction of the cured product of the desired shape, and repeating the process of irradiating light again. publicly known (for example, the above-mentioned Japanese Patent Application Laid-Open No. 62-3596)
No. 6).

[Problems to be Solved by the Invention] Since the photocurable resin undergoes contraction during its curing, it is important to reduce this shrinkage stress in order to improve the precision of the shaped object and prevent cracks.

[Means for solving the problem] The optical modeling method of the present invention irradiates a photocurable resin with light,
A first curing step in which the portion irradiated with light is cured so that uncured photocurable resin remains partially, and the cured product is stacked to form a three-dimensional object approximately in the desired shape; and a second curing step of curing the remaining uncured photocurable resin.

[Function] In the present invention, the three-dimensional object obtained in the first curing step is obtained by curing the photocurable resin by irradiating light so that uncured resin remains partially. By curing the resin so that some uncured photocurable resin remains in this way, the shrinkage stress caused by curing is dispersed, and
Since the absorption occurs in the uncured parts, in the first curing process, almost no shrinkage stress occurs as a whole (hereinafter sometimes referred to as "primary cured product").
becomes.

In the second curing step, the primary cured product obtained in the first curing step is further irradiated with light to harden the remaining uncured photocurable resin. By going through this second curing step, a hardened solid with high strength can be obtained. Also in this second curing step, as long as there is uncured photocurable resin around the curing process, almost no shrinkage stress is generated in the curing area. According to this method, shrinkage stress occurs during an extremely short period at the end of the curing process, and the shrinkage stress itself has an extremely small value.

[Example] FIGS. 1 to 4 are cross-sectional views showing an example of an apparatus for carrying out the first curing step of the present invention.

In the apparatus shown in FIG. 1, a photocurable resin 12 is housed in a container 11. A light transmitting window 13 made of a light transmitting plate such as glass is provided on the bottom of the container 11, and a light emitting part I5 with a built-in lens and an optical fiber 16. An optical system including an X-Y moving device 17 for moving the light emitting section 15 in the X-Y direction (X and Y are two orthogonal directions) in a horizontal plane, a light source 20, etc. is provided.

A base 21 is installed inside the container 11, and the base 21 can be raised and lowered by an elevator 22. These x
-Y6 moving device 17, elevator 22 is computer 23
controlled by

When producing a cured body using the above device, first the base 21
is positioned slightly above the transparent window 13, and the light beam 14 is scanned along the horizontal cross section of the target object. This scanning is performed by a computer controlled x-y B motion device 17.

After irradiating the entire horizontal cross section of the target shape (in this case, the part corresponding to the bottom or top surface), the base 2
1 is slightly raised to cause uncured photocurable resin to flow between the cured product 24 and the base 21, the same light irradiation as above is performed. By repeating this procedure, a primary cured body having a hollow shape can be obtained as a multi-N laminate.

In the above embodiment, a transparent window is provided on the bottom of the container so that light is irradiated from below the container, but in the present invention, a transparent window is provided on the side of the container 11, and light is emitted from the side of the container 11. It is also possible to irradiate. In this case, the base may be gradually moved laterally during the molding process.

In the above embodiment, the light is scanned by moving the optical fiber in the X-Y direction, but as shown in Figure 3 below, the light from the light source is reflected by a mirror and then converged by a lens. An optical system that irradiates the photocurable resin may be employed; in this case, the light beam can be scanned by rotating a mirror.

Further, the present invention may be applied to a known mask method, and a mask 26 having a slit 25 corresponding to the cross section of the target shape may be used, for example, as shown in FIG. Reference numeral 27 indicates a parallel light beam. Other symbols in FIG. 2 indicate the same members as in FIG. 1.

Although the apparatus shown in FIGS. 1 and 2 is configured to irradiate light from below the container, in the present invention, light may be irradiated from the upper opening of the container. Third
The apparatus shown in the figures and FIG. 4 is of a type that irradiates light from above the container.

In the apparatus shown in FIG. 3, the liquid level 12 of the photocurable resin 12 is
An optical system including a lens 28, a mirror 29, a mirror rotation drive device 29a, a light source 20, etc. is provided so as to irradiate the light beam 14 toward the direction a. The base 21 is inside the container 11.
is installed, and the base 21 can be raised and lowered by an elevator 22. These drive device 29a and elevator 22 are controlled by a computer 23.

When producing a primary cured body using the above-mentioned apparatus, first, the substrate 21a on the base 21 is positioned slightly below the liquid level 12a, and the light beam 14 is scanned along the horizontal cross section of the target shape. This scanning is performed using a computer-controlled mirror 29.
This is done by rotating the

After irradiating the entire horizontal cross section of the target shape (in this case, the part corresponding to the bottom surface), the base 21 is lowered slightly and uncured photocurable resin is poured onto the cured material 24. After that, by repeating this procedure of performing light irradiation in the same manner as above, a primary cured body having a desired shape can be obtained.

In the above embodiment, the base 21 is gradually lowered, but the liquid level 12a may be gradually raised by pouring more curable resin.

The apparatus shown in FIG. 4 uses a mask 26 having a slit 25 corresponding to the cross section of the object. Reference numeral 27 indicates a parallel light beam. Other symbols in FIG. 4 indicate the same members as in FIG. 3.

In the present invention, in such a first curing step, curing is performed by irradiation with light, and when a primary cured product having the desired shape is produced, a partially uncured photocurable resin remains. Let it harden.

The state in which the partially uncured photocurable resin remains is preferably such that the uncured portions are uniformly dispersed so that the shrinkage stress due to curing is dispersed as uniformly as possible.

In the present invention, it is preferable to cure the resin to the following cured states, for example, to obtain a primary cured product in which the uncured photocurable resin remains uniformly dispersed.

■ A semi-cured state in which the entire three-dimensional structure is uniform (that is, a state in which the polymerization of the photocurable resin is not completed).

■ A partially cured state in which the cured area (the area where the polymerization of the photocurable resin has been completed) and the uncured area (the area where almost no polymerization of the photocurable resin has occurred) are uniformly dispersed in three dimensions.

■ Partially cured state where semi-cured parts and hardened parts are evenly distributed in three dimensions.

■ Partially cured state in which cured, semi-cured and uncured areas are uniformly dispersed in three dimensions.

The partially cured states of ■ to ■ above may be, for example, a so-called unevenly cured state in which uncured parts are scattered among the cured parts, or a lattice-like or striped state between the cured parts. It is also possible to have an uncured portion in the surface.

The cured states shown in (1) to (2) can be formed by intermittent scanning of the light beam or by varying the intensity. The composition can also be formed by scanning the light beam so as to form an unirradiated area or a weakly irradiated area between the irradiated areas of the light beam. Furthermore, it can also be formed by using a mask having slits or small holes to irradiate only the necessary areas with the required amount of light.

In addition, in any of the forms of ■ to ■, the primary cured product obtained must be in a cured state that can maintain its shape, so the physical properties of the photocurable resin, the three-dimensional shape, The degree of hardening, the ratio of hardened parts to unhardened parts, etc. are determined as appropriate, taking into consideration the size and the like.

After obtaining the primary cured product having almost the desired shape in the first curing step in this way, it is taken out of the device and the second cured product is removed.
In the curing step, the entire primary cured body is irradiated with light to cure the remaining uncured photocurable resin.

FIG. 5 is a cross-sectional view showing an example of the second curing step,
The solid body 31 obtained in the first curing step is placed on a transparent plate 30 made of quartz glass or the like, and light 32 is irradiated simultaneously from above, below, and from the sides. Of course, the second curing step is not limited to the method of irradiating the entire three-dimensional object with light at the same time, but may also be a method of irradiating the entire object with light using a single moving light source. Alternatively, light may be irradiated from only one direction or two directions, and the posture of the three-dimensional object may be changed midway through.

As a result of the second curing step, the cured three-dimensional solid has a small curing shrinkage stress, and the shrinkage stress is evenly distributed throughout the solid, and has excellent dimensional stability and shape stability.

In the present invention, various substances that are cured by light irradiation can be used as the photocurable resin, such as modified polyurethane methacrylate, oligoester acrylate, urethane acrylate, epoxy acrylate, photosensitive polyimide, and amino alkyd. be able to.

As the light, various types of light such as visible light and ultraviolet light can be used depending on the photocurable resin used. The illumination may be regular light, but laser light has the advantage of increasing the energy level, shortening the molding time, and improving the molding accuracy by utilizing good light focusing. . Note that the light for the first curing step and the light for the second curing step may be the same or different.

[Effects of the Invention] As described above, according to the present invention, it is possible to reduce the shrinkage stress generated in the cured body in the optical modeling method and to uniformly disperse the shrinkage stress throughout the cured body. Therefore, it is possible to produce a highly accurate model without cracks and with almost no dimensional errors due to shrinkage.

[Brief explanation of the drawing]

1 to 5 are longitudinal cross-sectional views of the apparatus employed in the embodiment method, respectively. 12... Photocurable resin, 14... Luminous flux, 16
...Optical fiber 20...Light source, 21...
Base, 22...Elevator. Agent Patent Attorney Tsuyoshi Shigeno Figure 3 Figure 4 Figure 7

Claims (1)

[Claims] (1) The photocurable resin is irradiated with light, and the irradiated area is cured so that some uncured photocurable resin remains, and the cured resin is stacked to create approximately the desired shape. An optical modeling method comprising: a first curing step for forming a three-dimensional object; and a second curing step for irradiating the three-dimensional object with light to harden the remaining uncured photocurable resin.