JPH091674A - Photo-setting molding method - Google Patents

Abstract

PURPOSE: To provide a photo-setting molding method wherein optimal curing diameter and curing depth at each part in each layer of a product can be obtained. CONSTITUTION: Both an intensity and a spot diameter of ultraviolet laser beam to be applied to a photo-setting resin are controlled. When a convex lens which forms a beam expander is moved in a direction of optical axis so as to enlarge the spot diameter of the ultraviolet laser beam, a peak intensity lowers from Pi to P3 by the enlarged portion of the spot diameter so as to be a light intensity distribution shown by a two-dot chain line. At the same time, the intensity of the ultraviolet laser beam is lowered by an AOM module so as to lower the peak intensity from P3 to P2, so that a light intensity distribution having the peak strength P2 and a beam diameter W1 at a threshold Pth as shown by a solid line can be obtained. By irradiating a liquid resin with the ultraviolet laser beam having such a light intensity distribution, a curing diameter can be kept in the fixed size W1 by changing a curing depth of the liquid resin to D2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photo-curing molding method for selectively irradiating a liquid photo-curable resin with a light beam to form a three-dimensional shape.

[0002]

2. Description of the Related Art A liquid photo-curable resin (hereinafter, also referred to as "liquid resin") is irradiated with a strong light beam such as a laser beam to cure a part of the light beam to form an arbitrary three-dimensional shape. A photo-curing modeling device has been developed and put into practical use. This photo-curing modeling device is used for CA machine parts designed by CAD system.
It can be easily materialized using D data, and design confirmation and direct evaluation can be performed. In addition, it is an extremely useful device that meets the recent demand for high-mix low-volume production. A procedure of photo-curing modeling using this photo-curing modeling apparatus will be described with reference to FIG. As shown in FIG. 4, in the photo-curing modeling apparatus 102, an elevating table 112 that can move up and down is provided in a container 108 filled with a liquid resin 110. To model the product 120 as shown,
First, the lifting table 112 is set to the liquid level 1 of the liquid resin 110.
It is positioned at a height lowered from 10a by the thickness of the lowermost layer 120a. In this state, the galvano mirror 104 is rotated to scan the laser beam 106 within a required range, and the lowermost layer 120a is photo-cured. Next, the elevating table 112 is lowered from the lowermost layer by the thickness of the second layer 120b, and the second layer 120b is similarly photo-cured. Thereafter, in the same manner, the product 120 as shown in FIG. 4 is formed by sequentially photo-curing one layer from the bottom.

Here, the product 120 has a shape such that the radius of curvature becomes smaller toward the lower layer portion. Therefore, in order to form such a shape with high accuracy, it is necessary to stack the layers such that the lower layers have a smaller thickness as shown in FIG. At this time, when the thin layer and the thick layer are cured with the same light intensity, in the case of the thin layer, the already photo-cured layer below the thin layer is again irradiated with light. As a result,
The underlying layer is excessively hardened, resulting in discontinuity of the layer-to-layer connection surface and deformation of the product. In order to prevent this, it is necessary to change the magnitude of energy of the laser light with which the liquid resin is irradiated according to the thickness to be photocured. Conventionally, in such a case, the scanning speed of the laser beam 106 by the galvanometer mirror 104 has been changed. That is, in the case of a thick layer, the scanning speed of the laser beam 106 is decreased to increase the amount of light irradiated to the liquid resin 110 per hour, and in the case of a thin layer, the scanning speed of the laser beam 106 is increased. Reduce the amount of light emitted per hour. In this way,
The magnitude of the energy of the laser light to be irradiated was changed according to the thickness of the layer to be cured.

[0004]

However, in the method of changing the scanning speed of the laser beam 106 as described above,
Since the operation accuracy of the mechanical structure portion such as the galvano mirror 104 depends on the scanning speed, there is a problem that the accuracy of the manufactured product deteriorates when the scanning speed is increased. That is, since blurring and rattling when the galvanometer mirror 104 rotates increases as the scanning speed increases, the precision of the surface formed by photocuring also deteriorates accordingly, and the product with rough surface roughness is obtained. There was a problem that became. On the other hand, a method is conceivable in which the scanning speed is kept constant and the intensity of the laser light is changed by a variable light transmittance filter, an optical modulator or the like depending on the thickness of the layer to be cured. However, in this method, as the thickness of the cured layer changes, the diameter of the cured layer also changes. That is, when the intensity of the laser beam is reduced in order to reduce the thickness of the layer to be cured, the diameter of the laser beam that exceeds the threshold of the light intensity at which photocuring occurs is also reduced accordingly.
The diameter of the hardened part becomes smaller. For this reason, there is a problem that the cured dimension is displaced in the outer peripheral portion of the product, and the dimensional accuracy of the product is deteriorated. Furthermore, in order to form a photocured product with higher accuracy, it is required to obtain an optimum cured diameter and a cured depth by setting the light intensity distribution of the laser light to be the optimum shape in each part of each layer of the product. It was

Therefore, in the invention according to claims 1 to 3 of the present application, it is possible to provide a photo-curing molding method capable of obtaining an optimum curing diameter and curing depth in each part of each layer of a product. To aim. Moreover, it is an object of the invention according to claim 2 of the present application to provide a photo-curing modeling method capable of changing the curing depth without changing the curing diameter of the photo-curing resin by light rays. Moreover, it is an object of the invention according to claim 3 of the present application to provide a photo-curing molding method capable of easily and surely achieving the above objects.

[0006]

Therefore, in order to solve the above-mentioned problems, in the invention according to claim 1, the photocurable resin is selectively irradiated with a light beam to selectively select the photocurable resin. A photo-curing molding method for molding a three-dimensional shape by curing the light-curing resin, wherein the beam diameter of the light beam applied to the photo-curable resin is changed, or the beam diameter of the light beam is changed together with the light beam. By changing the intensity of the light rays, the light intensity distribution on the surface of the photocurable resin of the light rays is changed.

In order to solve the above-mentioned problems, in the invention according to claim 2, the photocurable resin is selectively irradiated with light rays to selectively cure the photocurable resin, thereby three-dimensionally curing the photocurable resin. Is a photo-curing molding method for molding the shape of, while changing the intensity of the light beam when irradiated to the photo-curable resin, the change of the curing diameter of the photo-curable resin due to the intensity change of the light beam. A photo-curing modeling method has been created, which is characterized by changing the beam diameter of the light beam applied to the photo-curable resin so as to cancel it.

Further, in the invention according to claim 3, there is provided the photo-curing molding method according to claim 1 or 2, wherein the change of the beam diameter of the light beam is caused by a lens forming a beam expander. We have created a photo-curing modeling method that is characterized in that it is performed by moving along a direction.

[0009]

The photo-curing molding method according to the first aspect of the present invention is a photo-curing method for molding a three-dimensional shape by selectively irradiating a photo-curable resin with a light beam to selectively cure the photo-curable resin. It is a curing and shaping method. In such a photo-curing molding method, by changing the beam diameter of the light beam irradiated on the photo-curable resin, or by changing the beam diameter of the light beam and the intensity of the light beam, The light intensity distribution on the surface is changed. As a result, the light intensity distribution of the laser light can be made into an optimum shape in each part of each layer of the product during the photocuring process, and the ratio of the cure diameter and the cure depth of the photocurable resin due to the irradiation of the light beam can be changed. By doing so, the optimum cure diameter and cure depth can be obtained. In this way, the photo-curing modeling method can obtain the optimum cure diameter and cure depth in each part of each layer of the product.

In the photo-curing molding method according to the second aspect of the present invention, in the photo-curing molding method, the intensity of the light beam when being irradiated on the photo-curable resin is changed, and the photo-curing property is changed by the change of the light intensity. The beam diameter of the light beam applied to the photocurable resin is changed so as to cancel the change in the cured diameter of the resin. As a result, the cured diameter of the photocurable resin does not change even if the intensity of light rays when irradiated changes,
Therefore, the curing depth can be changed while keeping the cured diameter of the photocurable resin constant. In this way, a photo-curing modeling method can be achieved in which the curing depth can be changed without changing the curing diameter of the photo-curing resin by light rays.

Further, the photo-curing molding method according to claim 3 is
In the photo-curing modeling method according to claim 1 or 2, the beam diameter of the light beam is changed by moving a lens constituting the beam expander along the optical axis direction. If the lens that constitutes the beam expander is moved along the optical axis direction, the focal point of the light beam will shift vertically from the surface of the photocurable resin, and as a result, the beam of the light beam on the surface of the photocurable resin will be displaced. The diameter will change. The movement of the lens forming the beam expander can be performed extremely easily and precisely by using an optical stage or the like. Further, since the beam expander is usually incorporated in the apparatus for performing the photo-curing modeling method, it is possible to realize the change in the beam diameter of the light beam without adding a new optical element. In this way, the photo-curing modeling method can easily and surely achieve the purpose of changing the curing depth without changing the curing diameter of the photo-curing resin by light rays.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment embodying the present invention will be described with reference to FIGS. First, the configuration of the photo-curing modeling apparatus used in the photo-curing modeling method of the present embodiment and the function of each part will be described with reference to FIGS. 1 and 2. FIG. 1 is a plan view showing the configuration of a photo-curing modeling apparatus used in the photo-curing modeling method of this embodiment, and FIG. 2 is a front view thereof. 1 and 2 show only the configuration of the optical system that is the center of the photo-curing modeling apparatus, and the supporting mechanism such as the mirror and the lens and the driving mechanism are omitted. As shown in FIG. 1, the photo-curing modeling apparatus 2 used in this embodiment has a He-Cd laser 4 as a laser light source. The ultraviolet laser light 6 emitted from the He-Cd laser 4 is reflected by the total reflection mirror 8, and the acousto-optical light modulator (Acoust
An o-Optic Modulator (hereinafter abbreviated as “AOM”) is incident on the module 10. The ultraviolet laser light 6 modulated in the AOM module 10 is emitted as a straight-advancing 0th-order light or slightly deflected primary light, and is directed downward (in a direction perpendicular to the paper surface of FIG. 1) by a total reflection mirror 12. It is reflected and further reflected in the horizontal direction by the total reflection mirror 14.

The AOM module 10 also has a function of changing the intensity of the ultraviolet laser light 6 applied to the liquid resin 40 described later. That is, AOM module 1
By changing the power of the ultrasonic wave applied to 0, the intensity ratio of the 0th-order light and the 1st-order light changes. As will be described later, since only the primary light of the ultraviolet laser light 6 is finally irradiated to the liquid resin 40, the liquid resin 40 is changed by changing the intensity ratio of the 0th order light and the 1st order light. The intensity of the ultraviolet laser beam 6 to be applied changes.

Subsequently, the ultraviolet laser light 6 passes through the mechanical shutter 16 and the iris diaphragm 18 and enters the convex lens 20 which constitutes the beam expander. This convex lens 2
0 and the convex lens 24 constitute a beam expander for expanding the beam diameter of the ultraviolet laser light 6. A spatial filter 22 is provided between the convex lens 20 and the convex lens 24. This spatial filter 2
2 is located at the focal point of the convex lens 20, and a slit is used as the spatial filter 22 in this embodiment. The 0th-order light of the laser light emitted from the AOM module 10 is blocked by the spatial filter 22, and only the 1st-order light passes through the spatial filter 22. Therefore, AO
By switching the ultraviolet laser light 6 between the 0th-order light and the 1st-order light at high speed by the M module 10, it is possible to perform shuttering of the ultraviolet laser light 6 at a high speed corresponding to the scanning speed of the galvano mirrors 28 and 30 described later. Become. This makes it possible to irradiate only the necessary portion of the liquid resin 40 while scanning the ultraviolet laser light 6 at high speed.

The convex lens 24 is connected to the ultraviolet laser beam 6
It is movable along the optical axis direction. The moving mechanism of the convex lens 24 is configured by attaching the lens holder of the convex lens 24 to a slide stage (not shown) using a pulse motor. By moving the convex lens 24 with such a moving mechanism,
The minimum focus point of the ultraviolet laser light 6 shifts vertically from the liquid surface of the liquid resin 40, and as a result, the spot diameter of the ultraviolet laser light 6 on the liquid surface of the liquid resin 40 changes. Thereby, as described later with reference to FIG. 3, the curing depth of the liquid resin 40 can be changed without changing the curing diameter of the liquid resin 40 by the ultraviolet laser light 6.

The ultraviolet laser light 6 emitted from the convex lens 24 and having the expanded beam diameter passes through the second iris diaphragm 26 and is reflected by the Galvano mirrors 28 and 30. The galvano mirror 28 rotates about a rotation axis perpendicular to the paper surface of FIG. 1, and the galvano mirror 30 rotates about a rotation axis in the paper surface of FIG. As a result, as shown by the broken line in FIG.
Is a resin container 3 provided below the galvanometer mirror 30.
8 is scanned over the entire surface. Further, as shown in FIG. 2, between the galvano mirror 30 and the resin container 38,
An fθ lens 32 is provided. This fθ lens 32
Is composed of a combination of several lenses, and collects the ultraviolet laser light 6 on the entire surface of the liquid resin 40 in the resin container 38 with a uniform spot diameter. The two iris diaphragms 18 and 26 are used only for aligning the optical axis of the ultraviolet laser light 6 when assembling the photo-curing modeling apparatus 2, and are fully opened after the optical axis alignment is completed. It The mechanical shutter 16 is closed for the safety of the operator when working around the resin container 38, and is fully opened when the photocuring modeling apparatus 2 is used.

Further, two two-dimensional optical sensors 34A and 34B are provided outside the resin container 38. These two-dimensional photosensors 34A and 34B have a square light receiving surface, and can detect which position of the square light receiving surface is hit when the light beam hits.
When the scanning of the ultraviolet laser light 6 by the galvanometer mirror 28 in the left-right direction in FIG. 1 is started, the ultraviolet laser light 6 is first irradiated to the two-dimensional optical sensor 34B as the original position.
If the deflection angle of the galvanometer mirror 28 is normal, the ultraviolet laser light 6 strikes the center of the light receiving surface of the two-dimensional optical sensor 34B. However, if the deflection angle of the galvano mirror 28 shifts due to a temperature change during use of the photo-curing modeling apparatus 2, the position where the ultraviolet laser beam 6 hits in the original position also shifts from the center of the light receiving surface of the two-dimensional optical sensor 34B. . Therefore, the displacement amount is measured by the two-dimensional optical sensor 34B, and the deflection angle of the galvanometer mirror 28 is corrected by a control unit (not shown). In this way, the scanning position by the galvano mirror 28 is always kept accurate even when used for a long time. Similarly, the deflection angle of the galvanometer mirror 30 is corrected using the two-dimensional optical sensor 34A.

The specific contents of how to obtain the amount of deviation for this correction will be described. When the deflection angle of the galvanometer mirror 28 is normal, the position on the surface of the two-dimensional optical sensor 34B that the ultraviolet laser light 6 impinges is E1, and its X-direction (left-right direction in FIG. 1) coordinates are x1 and Y-direction ( The coordinates (up and down direction in FIG. 1) are defined as y1. Also, galvano mirror 30
The position on the surface of the two-dimensional optical sensor 34A that the ultraviolet laser light 6 impinges when the deflection angle of is normal is E2, and X
The coordinate in the direction is x2, and the coordinate in the Y direction is y2. Furthermore, the coordinates of the position (including the shift amount) that the ultraviolet laser beam 6 actually hits while using the photo-curing modeling apparatus 2 are E3 (x3, y3) for the two-dimensional optical sensor 34B and E4 for the two-dimensional optical sensor 34A. (X4, y4). Of the shift amounts (offsets) of the Galvano mirrors 28 and 30, if the zero offsets are Δx and Δy and the gain offsets are ΔGx and ΔGy, the following equations (1) and (2) are established. x3 = ΔGx · x1 + Δx (1) x4 = ΔGx · x2 + Δx (2) Therefore, the values of ΔGx and Δx are given by the following expressions (3) and (4). ΔGx = (x3−x4) / (x1−x2) (3) Δx = x3−ΔGx · x1 (4) The values of ΔGy and Δy are similarly y1, y2, y3, y.
Required from 4.

Now, a method of adjusting the curing depth and the curing diameter in the photo-curing modeling apparatus 2 of the present embodiment having such a configuration will be described with reference to FIGS. FIG. 3 shows a light intensity distribution of the ultraviolet laser light 6 on the surface of the liquid resin 40. The vertical axis of FIG. 3 represents the light intensity of the ultraviolet laser light 6, and the light intensity increases toward the bottom. The light intensity threshold value Pth is a threshold value that causes photocuring when the liquid resin 40 is irradiated with light intensity higher than this. The horizontal axis of FIG. 3 indicates the beam spot diameter. As shown in FIG. 3, when the liquid laser 40 is irradiated with the ultraviolet laser light 6 with the light intensity distribution of the peak intensity P1 shown by the alternate long and short dash line, the portion D1 that exceeds the threshold Pth is photo-cured. That is, the curing depth is D1. On the other hand, the AOM module 10 shown in FIGS.
When the intensity of the ultraviolet laser light 6 is weakened by the irradiation with the light intensity distribution of the peak intensity P2 indicated by the broken line, the curing depth of the liquid resin 40 becomes D2. In this way, the curing depth of the liquid resin 40 can be adjusted by adjusting the intensity of the ultraviolet laser light 6 to be applied. However, along with this, as shown in FIG. 3, the hardening diameter of the liquid resin 40 also changes from W1 to W2, and the hardening diameter becomes smaller, so that the dimensional accuracy of the product deteriorates as described above. It will be.

Therefore, in the photo-curing molding method of this embodiment, the curing diameter is made constant by adjusting the intensity of the ultraviolet laser light 6 and the spot diameter of the laser beam. That is, first, the convex lens 24 of FIGS. 1 and 2 is moved in the optical axis direction to increase the spot diameter of the ultraviolet laser light 6. As a result, the peak intensity decreases to P3 as the spot diameter increases,
The light intensity distribution is shown by the chain double-dashed line. At the same time, AOM
The module 10 reduces the intensity of the ultraviolet laser light 6 to reduce the peak intensity from P3 to P2. by this,
As shown by the solid line in FIG. 3, a light intensity distribution with a peak intensity P2 and a beam diameter W1 at the threshold Pth is obtained. By irradiating the liquid resin 40 with the ultraviolet laser light 6 having such a light intensity distribution, the hardening diameter of the liquid resin 40 can be changed to D2 and the hardening diameter can be maintained at a constant size W1. Thus, in the photo-curing modeling method of this embodiment, the ultraviolet laser light 6
The hardening depth of the liquid resin 40 can be changed without changing the hardening diameter of the liquid resin 40.

Further, in the photo-curing modeling method of this embodiment, the light-intensity distribution of the ultraviolet laser light 6 is arbitrarily changed to obtain the optimum curing diameter and curing in each part of each layer of the product during the photo-curing process. You can get the depth. That is, as described above, when the spot diameter of the ultraviolet laser light 6 is increased by the movement of the convex lens 24, the light intensity distribution changes from the one shown by the one-dot chain line to the one shown by the two-dot chain line. As shown in FIG. 3, the hardening diameter in this case changes from W1 to W3, and the hardening depth changes from D1 to D3. In this way, the light intensity distribution can be changed only by changing the spot diameter. In addition to this, by weakening the intensity of the ultraviolet laser light 6 in the AOM module 10, as described above, the light intensity distribution can be changed from the one indicated by the chain double-dashed line to the one indicated by the solid line. As described above, the light intensity distribution of the ultraviolet laser light 6 can be arbitrarily changed by changing the spot diameter, or by changing the spot diameter and the light intensity. Therefore, the curing diameter and the curing depth by the ultraviolet laser light 6 can be adjusted to the optimal ratio and the optimal size, and the curing diameter and the curing depth in each part of each layer of the product at the time of photocuring modeling can be optimized. Can be converted. As a result, more accurate photo-curing modeling can be performed.

In this embodiment, the ultraviolet laser beam 6 emitted from the He-Cd laser 4 is used as a light beam for curing the photocurable resin (liquid resin) 40.
Ultraviolet laser light from another ultraviolet laser light source such as a laser may be used. Further, depending on the type of the photo-curable resin, it is possible to use laser light of other wavelengths or light rays other than laser light. Further, in the present embodiment, as a method of adjusting the intensity of the ultraviolet laser light 6, the change of the intensity ratio of the 0th order light and the 1st order light by the AOM module is used, but a variable light transmittance filter is used. Other methods are also possible. An EOM (Electro-Optic Modulator) module may be used instead of the AOM module for intensity adjustment and light deflection.

Further, in this embodiment, the ultraviolet laser light 6 is used.
A method of moving the convex lens 24 constituting the beam expander along the optical axis direction is used as a method of adjusting the spot diameter of the beam. However, by moving (up and down) the fθ lens 32 along the optical axis direction. Can also adjust the spot diameter. Other methods such as adding a lens dedicated to adjusting the spot diameter other than the beam expander lenses 20 and 24 and the fθ lens 32 and moving the dedicated lens along the optical axis direction may be used. . Further, in this embodiment, the slit is used as the spatial filter 22, but a mask pattern drawn on a glass plate or the like may be used as the spatial filter. Structure, function, number, etc. of other parts of the photo-curing method
The size, connection relationship, etc. are not limited to those in this embodiment.

[0024]

According to the first aspect of the present invention, a photo-curing molding method is created in which the light intensity distribution is changed by changing the beam diameter of a light beam, or by changing the beam diameter and the light intensity. In addition, the light intensity distribution of the laser light can be optimized in each part of each layer of the product during the photocuring process, and the ratio of the cure diameter and the cure depth of the photocurable resin due to the irradiation of the light beam can be changed. Thus, the optimum hardening diameter and hardening depth can be obtained. As a result, it becomes a practical photo-curing molding method capable of optimizing the cured diameter and the cured depth in each part of each layer of the product to form a more accurate product.

According to the second aspect of the present invention, the light for changing the beam diameter of the light beam so as to change the intensity of the light beam applied to the photocurable resin and cancel the change in the cure diameter of the photocurable resin. Due to the creation of a curing modeling method, the cured diameter of the photocurable resin does not change even if the intensity of the light beam when irradiated changes, and the curing depth is maintained while keeping the cured diameter of the photocurable resin constant. Can be changed. As a result, it becomes a practical photo-curing modeling method capable of maintaining the dimensional accuracy of the product to be molded with high accuracy while changing the thickness of the layer to be photo-cured.

Further, in the invention according to claim 3, since a photo-curing modeling method for changing the beam diameter of the light beam by moving the lens constituting the beam expander along the optical axis direction is newly created. The beam diameter can be changed easily and precisely without adding a special optical element. In this way, a practical photo-curing modeling method can easily and surely achieve the purpose of changing the cure depth without changing the cure diameter of the photo-curable resin by light rays.

[Brief description of the drawings]

FIG. 1 is a plan view showing a configuration of a photo-curing modeling apparatus used in an embodiment of a photo-curing modeling method according to the present invention.

FIG. 2 is a front view showing the configuration of a photo-curing modeling apparatus used in an embodiment of the photo-curing modeling method.

FIG. 3 is an explanatory diagram showing a method of adjusting a photo-curing depth and a curing diameter in an example of the photo-curing modeling method.

FIG. 4 is an explanatory diagram showing a conventional photo-curing modeling method.

[Explanation of symbols]

 2 photo-curing modeling device 6 rays 40 photo-curing resin

Claims (3)

[Claims] 1. A photocurable molding method for modeling a three-dimensional shape by selectively irradiating a photocurable resin with a light beam to selectively cure the photocurable resin, wherein the photocurable resin By changing the beam diameter of the light beam applied to the resin, or by changing the beam diameter of the light beam and the intensity of the light beam, the light intensity distribution of the light beam on the surface of the photocurable resin is changed. A photo-curing modeling method comprising: 2. A photocurable molding method for molding a three-dimensional shape by selectively irradiating a photocurable resin with a light beam to selectively cure the photocurable resin, wherein the photocurable resin A beam of the light beam irradiated to the photocurable resin so as to change the intensity of the light beam when irradiated on the resin and cancel the change in the curing diameter of the photocurable resin due to the change in the intensity of the light beam. A photo-curing modeling method characterized by changing a diameter. 3. The photo-curing modeling method according to claim 1, wherein the beam diameter of the light beam is changed by moving a lens constituting a beam expander along an optical axis direction. A photo-curing molding method characterized by the above.