JPH06297587A - Three-dimensional shaping method - Google Patents

Abstract

PURPOSE:To prevent the internal stress accompannied by the curing of a resin from deviating in a definite direction by changing the direction of the internal stress at every cross section layer to disperse the same as the whole of a molded product by scanning a photo-setting resin at a parallel equal interval by laser beam and relatively rotating a scanning direction at an arbitrary angle. CONSTITUTION:A desired three-dimensional shape is formed in a threedimensional CAD system 1 and converted to an STL format to be sent to an NWS 2. The EWS 2 cuts data on a Z-axis at an equal interval DELTAZ in parallel to an XY plane and the desired three-dimensional shape is displayed as the aggregate of the data of respective cross-sectional shapes. A forming stand 13 positioned in a photo-setting resin 7 so as to be set under the liquid level of the resin 7 by the interval DELTAZ of a cross section and covered with a liquid photo-setting resin layer with a thickness DELTAZ. The surface of the photo-setting resin is scanned in the shape corresponding to the cross-sectional shape of the lowermost part by the laser beam from a laser XY scanner 4 and the surface resin layer is cured to shape the lowermost cross-section layer on the forming stand 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional modeling method for molding a three-dimensional shape by irradiating a laser beam to cure a photocurable resin.

[0002]

2. Description of the Related Art Recently, as a method for forming various three-dimensional shapes, a liquid photocurable resin is scanned with a laser beam to form a cured layer of the resin, and a plurality of the cured layers are laminated to form a desired layer. A three-dimensional modeling method for modeling a three-dimensional shape has been widely used.

A conventional three-dimensional modeling method will be described below. FIG. 3 shows a schematic configuration of a conventional 3D modeling apparatus to which the principle of the 3D modeling method is applied.

The three-dimensional modeling apparatus comprises a part for processing three-dimensional shape data and a device for modeling the three-dimensional shape based on this data.

The data processing part is a three-dimensional CAD system 1 for creating a three-dimensional shape, and an EWS (engineering workstation) for calculating data for a modeling apparatus based on the three-dimensional shape created by the three-dimensional CAD system 1. ) 2.

On the other hand, the apparatus for forming a three-dimensional shape comprises a resin tank 10 containing a liquid photocurable resin 7, and a forming table 13 which can be moved up and down by an elevating device 6 is provided on the resin tank 10. There is. As the photo-curable resin,
Various resins that are cured by light irradiation can be used, for example, epoxy-based resins such as epoxy acrylate and modified polyurethane methacrylate.

Above the resin tank 10, a laser XY scanning device 4 for irradiating a laser beam generated by a laser generator 5 through an optical fiber 9 onto the liquid surface of the photocurable resin 7 while freely scanning in the XY directions. Is provided. In addition,
The laser generator 5, the laser XY scanning device 4, and the lifting device 6 are controlled by the NC controller 3 based on the data of the EWS 2.

Next, the operation of the above apparatus will be described. First, a desired three-dimensional shape is created by the three-dimensional CAD system 1, and the three-dimensional shape data is stored in STL (storage).
List) format and sent to EWS2. The EWS 2 cuts the STL-formatted data of the three-dimensional shape in parallel with the XY plane at equal intervals ΔZ along the Z-axis, and represents a desired three-dimensional shape as an aggregate of data of each cross-sectional shape. The value of ΔZ is determined by the type of photocurable resin and the power of laser light.

Next, the forming table 13 is positioned below the liquid surface of the photocurable resin 7 by the interval ΔZ of the cross section, and the forming table 13 is formed.
Is covered with a liquid photocurable resin layer having a thickness ΔZ. The laser XY scanning device 4 scans the surface of the photocurable resin 7 with a laser beam in a shape corresponding to the bottom cross-sectional shape of the three-dimensional shape to cure the surface resin layer and form the bottom cross-section layer on the forming table 13. To model.

At this time, as shown in FIG. 4, the laser beam is separated by an interval 2 in the X-axis direction with reference to the diameter of the laser beam.
Scanning is performed from one end of the cross-sectional shape 20 toward the other end parallel to the Y-axis while shifting by two, as indicated by arrow 21.

When the one cross-section layer is formed, the elevating device 6 further immerses the forming table 13 in the uncured photocurable resin by the interval ΔZ of the cross section, and the upper portion of the resin-cured layer previously formed again. It is covered with a liquid photocurable resin layer having a thickness ΔZ. Then, similarly to the above, the laser XY scanning device 4 scans the surface of the photocurable resin 7 with laser light in a shape corresponding to the second cross-sectional shape following the lowermost cross-sectional layer, and the laser light is scanned on the uppermost part of the lowermost cross-sectional layer. The second cross-section layer is cured and shaped.

By repeating this process up to the highest part of the three-dimensional shape, a plurality of cured layers of the photocurable resin are laminated to form a three-dimensional shape.

[0013]

The photocurable resin used in the three-dimensional modeling apparatus shrinks by about 2 to 5% in volume ratio when it is cured by being irradiated with laser light. Therefore, when the uncured photocurable resin is irradiated with the laser light, as shown in FIG. 5A, when the uncured photocurable resin 53 exists around the region 51 irradiated with the laser light, , The region 51 is irradiated with the laser beam and the resin is cured and contracts to become 52.
Since the uncured resin in the surroundings is supplied while being supplied as shown by the arrow 54 so as to compensate for this curing shrinkage amount, the curing progresses, so that stress due to shrinkage at the time of curing hardly occurs.

However, as shown in FIG. 5B, the resin 5 which has already been hardened around the region 57 irradiated with the laser beam.
When 5 is present, when the uncured photocurable resin is irradiated with laser light, the resin in the region 57 hardens and tries to shrink, but since the uncured resin is not supplied from the surroundings, The cured portion 55 is attracted to the resin being cured,
Tension 56 is generated. That is, internal stress is generated in the direction from the portion that is cured first to the portion that is cured later due to contraction accompanying the curing of the resin.

Further, the photo-curing resin is cured by about 98% of the irradiated portion when the laser beam is irradiated, and it takes a considerable time to be completely cured. Therefore, once cured, the curing further progresses, the resin shrinks inside the molded product, and further stress is generated.

Therefore, if the photocurable resin is scanned with a laser beam in a direction parallel to the X axis or the Y axis as in the conventional case, for example, the laser beam is linearly scanned in the direction of an arrow 69 as shown in FIG. , The irradiation area of laser light is 63, 64, 65, 6
6 and 67, the photocurable resin is also gradually and continuously cured in the same direction as the scanning direction of the laser light as the laser light is scanned. Therefore, the internal stress 68 is generated and accumulated such that the first cured portion 61 is pulled by the later cured portion 62 as shown by the arrow 68 due to the contraction accompanying the curing of the resin.

That is, in the conventional scanning method, the internal stress 68 is generally biased in the same direction, for example, in the direction parallel to the X axis or the Y axis, and as a result, the molded product may be deformed such as warped.

The present invention provides a method for eliminating unevenness of internal stress and preventing deformation of a molded product in three-dimensional shape molding.

[0019]

In order to achieve the above-mentioned object, the present invention is to form a cross-section layer by scanning a laser beam in parallel with a shape corresponding to the cross-section shape at equal intervals to cure the photocurable resin. The method of rotating the scanning direction of the laser beam relative to the photo-curable resin layer by an arbitrary angle is performed in each step or every several steps.

[0020]

According to the above-mentioned method of the present invention, the scanning direction of the laser beam is rotated relative to the photocurable resin layer by an arbitrary angle in every step or every several steps in forming the cross-section layer. As a result, the scanning direction of the laser beam shifts for each cross-section layer or every several cross-section layers, and the progress direction of the curing of the resin also shifts accordingly. Changes to. Therefore, the direction of stress is dispersed in the entire molded product.

[0021]

EXAMPLES An example of the present invention will be described below.
FIG. 2 shows a schematic configuration of a three-dimensional modeling apparatus to which the method of the present invention is applied, but it is basically the same as the conventional configuration of FIG.
It differs from the configuration of FIG. 3 in that a rotating device 14 for rotating the forming table 13 is provided. Therefore, parts having the same functions as those in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

The operation of the apparatus shown in FIG. 2 will be described. First, a desired three-dimensional shape is created in the three-dimensional CAD system 1, and the three-dimensional data is converted to the STL format and sent to the EWS 2. The EWS 2 cuts the STL-formatted data of the three-dimensional shape at equal intervals ΔZ in parallel with the XY plane along the Z-axis, and represents a desired three-dimensional shape as an aggregate of data of each cross-sectional shape.

Next, the forming table 13 is positioned below the liquid surface of the photocurable resin 7 by the interval ΔZ of the cross section, and the forming table 13 is formed.
Is covered with a liquid photocurable resin layer having a thickness ΔZ. The laser XY scanning device 4 scans the surface of the photocurable resin 7 with laser light in a shape corresponding to the bottom cross-sectional shape to cure the surface resin layer and form the bottom cross-section layer on the forming table 13.

At this time, as shown in FIG. 1 (a), the laser light is shifted in the X-axis direction by an interval 17 determined based on the diameter of the laser light while being parallel to the Y-axis as shown by an arrow 16. Scanning is performed from one end of the cross-sectional shape 15 toward the other end. The laser light may be scanned in parallel with the X-axis while being shifted in the Y-axis direction by an interval determined based on the diameter of the laser light.

When one cross-section layer is formed, the elevating device 6 further immerses the forming table 13 in the uncured photocurable resin by the interval ΔZ of the cross section, and the upper part of the resin-cured layer previously formed again is removed. It is covered with a liquid photocurable resin layer having a thickness ΔZ. At the same time, the forming table 13 is rotated by an arbitrary angle θ by the rotating device 14, and as shown in FIG. 1B, the data of the second cross-sectional shape following the lowermost cross-sectional layer on the EWS 2 also has the same angle θ.
Just rotate. After that, a laser beam is applied to the surface of the photocurable resin 7 by the laser XY scanning device 4 in the shape corresponding to the rotated sectional shape 18 in the same manner as described above, and the second sectional layer is formed above the lowermost sectional layer. Harden and model.

By repeating this process up to the highest part of the three-dimensional shape, a three-dimensional shape is formed by laminating a plurality of cured layers of the photocurable resin.

The operation of rotating the forming table 13 and the cross-sectional shape data may be carried out every several layers in the step of forming the hardened cross-sectional layer, and when the data is uniformly rotated along the Z axis of the desired three-dimensional shape, It is even more effective in preventing stress bias.

As described above, by changing the scanning direction of the laser beam for each cross-section layer or every several cross-section layers, the hardening direction of the resin changes for each cross-section layer or every several cross-section layers, and as a result, when the resin is hardened. Since the internal stress due to the shrinkage of the molded product is dispersed as a whole and is not biased in a certain direction, it is possible to prevent the molded product from being deformed such as warped.

[0029]

As described above, according to the present invention, the photo-curing resin is scanned with laser light at equal intervals in parallel, and the scanning direction is photo-cured in one step or every several steps of the step of forming the cured cross-section layer. By rotating it relative to the flexible resin layer by an arbitrary angle, the direction of internal stress due to the hardening of the resin may change for each cross-section layer or for several cross-section layers, and the molded product may be dispersed and biased in a certain direction. Since it disappears, deformation such as warping of the molded product can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing a laser beam scanning pattern in the method of the present invention.

FIG. 2 is a schematic configuration diagram of a three-dimensional modeling apparatus to which the method of the present invention is applied.

FIG. 3 is a schematic configuration diagram of a three-dimensional modeling apparatus to which a conventional method is applied.

FIG. 4 is a plan view showing a laser beam scanning pattern in a conventional method.

FIG. 5 is a plan view showing a curing pattern of a photocurable resin.

FIG. 6 is a conceptual diagram illustrating the principle of internal stress generation.

[Explanation of symbols]

 1 Three-dimensional CAD system 2 EWS 3 NC control device 4 Laser XY scanning device 5 Laser generation device 6 Elevating device 7 Photocurable resin 8 Modeling object 9 Optical fiber 10 Resin tank 13 Forming table 14 Rotating device 15 Cross-sectional shape before rotation 16 Rotation Previous laser scanning path 17 Laser beam scanning interval 18 Cross-sectional shape after rotation 19 Laser scanning path after rotation 20 Cross-sectional shape 21 Laser scanning path 22 Laser beam scanning interval

Claims (1)

[Claims] 1. A desired three-dimensional shape is expressed as a set of data relating to cross-sectional shapes cut at equal intervals, and based on this data, the steps (1) and (2) below are repeated to perform photocuring of a plurality of layers. In a three-dimensional modeling method of laminating a resinous resin layer to form a three-dimensional shape, a laser beam is scanned at equal intervals in parallel, and the scanning direction is (1), (2) for each set or a plurality of sets of steps. A three-dimensional modeling method comprising rotating the photocurable resin layer relative to an arbitrary angle. (1) A laser beam is scanned from above a water tank filled with an uncured liquid photocurable resin to cure a surface resin layer having a shape corresponding to the cross-sectional shape. (2) The cured resin layer is submerged in the uncured liquid photocurable resin by the distance of the cross section.