JP3721477B2 - Stereolithography - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-precision optical modeling method by shape correction for curing a photo-curing resin to produce a resin model.
[0002]
[Background Art and Problems to be Solved by the Invention]
Conventionally, in order to correct the unit hardening shape, the cross-sectional contour of the solid figure input to the computer is calculated, and a pseudo three-dimensional offset is performed from the inclination of the surface forming the solid figure. However, it was troublesome and it was difficult to perform complete correction.
[0003]
In addition, in the conventional method, there is a lifting platform on which a cured product is placed in a resin liquid layer, and since this was submerged while being laminated, the resin extruded by the lifting platform flowed onto the lifting platform, and the modeled object fluctuated. It may end up.
[0004]
Furthermore, in the conventional method, since it is necessary to pour overflowing resin into the auxiliary tank, a dedicated auxiliary tank is required.
[0005]
In the conventional method, the center of the light beam is fixed in the direction perpendicular to the resin liquid surface or in the direction perpendicular to the resin liquid surface, and along the surface forming the solid to irradiate in a circular arc. Can not be stacked.
[0006]
In conventional methods, it is possible to add a single color by mixing pigments into the resin, but in order to partially change the color of the resin that forms the model, it is necessary to replace the resin. And not practical.
[0007]
When uncured resin remains in the modeled object, the shape may change when irradiated with light. This has traditionally been considered malicious and unavailable.
[0008]
A model is generally modeled with a liquid resin color. For this reason, it is difficult to confirm the shape in the middle of modeling.
[0009]
There are cases where pigments, dyes, powders, etc. are mixed into liquid resin, causing absorption and scattering of light to generate a cured shape, but only a limited shape is generated. I can't.
[0010]
[Means for Solving the Problems]
Therefore, the high-precision optical modeling method by shape correction according to the present invention is characterized in that a correction is performed from an original solid figure input to a computer, a cross section is calculated from the obtained solid figure, and modeling is performed. .
[0011]
The three-dimensional modeling apparatus described in the present invention includes a cylinder with a piston built in a resin container, and a resin fixing base is attached to the piston so that the piston can be moved up and down freely. So that it does not flow back into the resin container and flow back onto the resin fixing table, and the photo-curing resin liquid in the resin container is discharged from the resin jet nozzle provided on the resin fixing table, and then the resin fixing table is photo-cured. Form the resin film for one layer by smoothing the resin liquid with a smooth plate, and irradiate the resin film with the light beam from the light source to obtain a one-layer shaped object, and repeat this to form a model while stacking the shaped objects It is what I did.
[0012]
Further, the uncured resin is left in the internal local part of the modeled object to model. Later, light is applied to change the shape of the modeled object (or obtain the force to be changed) using the force that cures and shrinks the uncured resin.
[0013]
A photochromic agent is mixed in the resin in advance to obtain a stable cured shape, and the color of the cured resin is changed to facilitate discrimination from the uncured resin.
[0014]
Since the high-accuracy stereolithography method by shape correction according to the present invention is configured as described above, it is possible to correct the spread of the cured resin and the deformation due to the shrinkage of the resin, thereby enabling precise processing.
[0015]
Since the original solid figure input to the computer is corrected, the cross section is calculated and the modeling is performed, so that the necessary diagnosis of the support is automatically diagnosed, so that there is no processing failure due to lack of support.
[0016]
In addition, the portion where the filling scan with the light beam is performed is not subjected to three-dimensional distortion due to the progress of post-curing by performing irradiation processing at a scanning speed faster than the contour scanning in a range where uncured resin does not remain inside.
[0017]
Modeling with precise thickness control based on surface data and solid data becomes possible.
[0018]
By changing the scanning speed, the size of the unit curing shape by the light beam is changed, and continuous control of the laser output is not required, so that the apparatus can be realized easily.
[0019]
The machining accuracy can be controlled by partially changing the stacking interval.
[0020]
By changing the irradiation direction and light distribution of the light beam with a small light control device consisting of a lens or hologram, the processing accuracy is improved by creating and processing a hardened shape that fits the surface of the solid figure smoothly. be able to.
[0021]
By disposing the cylinder in the resin liquid layer and lowering the resin liquid with the piston so that the resin liquid does not overflow, it is possible to prevent the molded article from shaking and improve the processing accuracy.
[0022]
The resin discharged by the piston is moved to the upper part of the resin container outside the cylinder provided in the resin container, and this is discharged onto the resin fixing table and laminated, thereby eliminating the need for an auxiliary tank and making the processing device compact. Can be.
[0023]
Photo-curing resin with photo-reactivity has a large change in characteristics due to temperature, but when supplying resin partially taken out from the resin container due to piston pressure or the like, the light beam can be controlled by controlling the temperature of the resin to be supplied. Since the liquid surface can be kept at a constant temperature from the surface where the irradiation is performed, there is an energy saving effect, the apparatus becomes simple, temperature control can be performed quickly, and the life of the resin can be extended.
[0024]
Irradiation with a multi-wavelength light beam using a wavelength-dependent color former can selectively change the color of a cured product that partially or entirely creates.
[0025]
The modeled object that is formed by leaving the uncured resin remaining in the internal local area is used to change the shape of the modeled object (or the force to be changed) by using the force that the uncured resin cures and shrinks later. Can get).
[0026]
By previously mixing a photochromic agent in the resin, a cured shape that cannot be obtained by mixing pigments, dyes, powders, or the like can be obtained. Moreover, it can identify easily as what changed the modeling thing during modeling processing.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0028]
1 to 3 show an example of a three-dimensional modeling apparatus that obtains a three-dimensional model by laminating a photo-curing resin that embodies the present invention.
[0029]
Reference numeral 1 denotes a resin container. A cylinder 2 is provided in the resin container 1, and the cylinder 2 is immersed in the resin liquid. A piston 9 is incorporated in the cylinder 2 through a rubber packing 10 so as to be movable up and down, and is lifted and lowered by a piston lift 7 attached to the resin container 1. The piston 9 is normally lowered while pushing out the resin liquid in the cylinder 2 from below.
[0030]
The piston 9 is provided with a resin fixing table 4. The piston 9 is lowered while being attached to the resin fixing table 4 while the object fixed by the laser beam irradiation is attached to the resin fixing table 4. The resin in the cylinder 2 is pushed out. Since the extruded resin liquid moves into the resin container 1 outside the cylinder 2, the water level of the resin liquid rises, and the resin liquid is pumped up by the resin pumping pump 11.
[0031]
A smooth plate 3 is provided on the upper end surface of the cylinder 2 and is driven by a motor 5. Accordingly, the resin pumped up by the resin pumping pump 11 is discharged and supplied from the resin jet 8 provided on the cylinder 2, and the motor 5 is driven to operate the smoothing plate 3. It moves along the upper end surface to form a thin resin film for one layer. Reference numeral 6 denotes a guide for the smooth plate 3 attached to the upper end surface of the cylinder 2, and 12 denotes a solid matter prevention network provided at the upper part in the resin container.
[0032]
A light source for irradiating the resin film with a light beam made of laser light or the like is installed on the top of the resin container 1 (not shown). By changing the irradiation direction of the light beam emitted from this light source using a lens or hologram, it is possible to create a hardened shape that smoothly fits the surface of a three-dimensional figure and to improve the processing accuracy. Can be made.
[0033]
Since photo-curing resin having photoreactivity has a large change in characteristics due to temperature, the temperature of a heater or the like near the piping system for supplying resin partially taken out from the resin container by the pressure of the piston or the like, or the resin outlet 8 It is desirable to provide a control means. By controlling the temperature of the resin supplied by this temperature control means, it is possible to keep the temperature constant from the surface where the light beam is irradiated, so there is an energy saving effect, the device is simplified, and temperature control can be performed quickly. In addition, the service life of the resin will be extended.
[0034]
In addition, by mixing a wavelength-dependent color former in the resin liquid and irradiating with a multi-wavelength light beam, the color of the cured product that creates a part or the whole can be selectively changed. Convenient to.
[0035]
Next, a shape correction method will be described with reference to FIGS.
[0036]
For example, when performing cylindrical modeling as shown in FIG. 4, in order to perform modeling with high accuracy along the cylinder 21, a beam center graphic 22 that is shifted from the shape of the cylinder 21 by the correction amount of the unit cured shape is created in advance. If the beam center position is aligned with this cross section, the cured product does not jump out of the cylinder 21 and high accuracy modeling can be performed.
[0037]
For that purpose, first, a unit cured shape 23 is defined as a cross section of one cured product that is generated when a light beam such as a laser beam is scanned once on a surface of an ultraviolet curable photocuring resin without a cured product. An example of the unit cured shape 23 is shown in FIG.
[0038]
In order to correct the original solid figure inputted by the computer using the unit cured shape 23, first, the unit cured shape 23 is copied using an electron microscope or the like, or the shape is obtained by computer simulation. The correction amount in the case of stacking on a plane with the irradiation position of the beam for generating this shape as the center O is obtained by the distance between the end surface of the unit cured shape 23 and the center O. The correction amount 24 thus obtained can be illustrated as shown in FIG. This correction amount 24 is stored in a computer so that it can be referred to. The unit cured shape 23 varies depending on the scanning speed and the intensity of the light beam, for example, the laser beam intensity. Therefore, several samples are taken, and the correction amount 24 actually used is the one stored in advance as described above.
[0039]
Since the three-dimensional shape to be obtained is composed of a large number of surfaces, if the surface of the unit cured shape 23 is shifted by the correction amount 24 as shown in FIG. 6, a beam center position graphic can be created on the computer. it can. Thereafter, a cross-section of the beam center position figure is calculated, and based on this, a light beam is scanned while irradiating, whereby a highly accurate three-dimensional figure can be created.
[0040]
FIG. 7 is a diagram for explaining a method of filling and scanning a thickness portion of a solid figure having a hollow portion.
[0041]
In this case, first, the original solid figure 31 having a predetermined thickness input to the computer is subjected to correction of the unit hardening shape 23 on both sides in the thickness direction so as to be separated from the original solid figure 31 by a certain distance. Figures 32 and 33 are created. Next, a cross-section is calculated based on the figures 32 and 33, and a fill scan is performed between the pair of figures 32 and 33 with a light beam at a scanning speed faster than the contour scan in a range where no uncured resin remains inside. Therefore, it is possible to process at a constant thickness at a higher speed. If the uncured resin remains, curing proceeds and the shape changes when strong light is applied after the molded solid is taken out. On the other hand, excessively applying light energy slows the processing speed and is not practical. Therefore, it is optimal to proceed the lamination at a high speed within a range where no uncured resin remains in the lamination interval.
[0042]
FIG. 8 is for explaining an apparatus for obtaining a unit cured shape that smoothly fits a three-dimensional figure.
[0043]
FIG. 8 illustrates the case where the lens 13 is used. According to this, it is possible to obtain a unit cured shape 23 ′ in which the normal unit cured shape 23 is inclined at a predetermined angle with respect to the optical axis of the light beam 25. In this way, by irradiating a beam obliquely with respect to the liquid surface to change the unit curing shape, it is possible to perform stacking that fits in a three-dimensional shape.
[0044]
FIG. 9 is a flowchart showing the processing steps of the high-precision optical modeling method by shape correction according to the present invention.
[0045]
[Example] Visible light initiator (BTTB / ketocoumarin {4 to 1 mixture) in a resin (trimethylolpropane triacrylate, 1,6-hexanediol diacrylate {mainly a mixture of 1: 1)} in advance }), A small amount of UV initiator light (2-hydroxy-2-methyl-1-phenylpropan-1-one), a photochromic agent (4, 4 ′, 4 ″ -trisdimethylamino itriphenylmethane) A small amount is mixed, and a two-dimensional solid shape is formed by selectively irradiating with two wavelengths of an argon laser wavelength of 514.5 nm and a helium-cadmium laser wavelength of 325 nm.
[0046]
FIG. 10 is a modeled object that is formed by intentionally leaving uncured resin. Later, these are irradiated with a lamp or the like, and a is used as a material for bundling lines and the like. b is used for a connector or the like. c is an example used for an integrated exposure meter.
[0047]
Photochromic agent (4, 4 ′, 4 ″ -trisdimethylamino itriphenylmethane in advance in resin (trimethylolpropane triacrylate, 1,6-hexanediol diacrylate {mainly a 1: 1 mixture)}) ) Is mixed in a small amount, and the resin curing reaction is suppressed, high-precision processing is possible, and the shape in the middle of modeling can be easily confirmed with a discolored color.
[0048]
【The invention's effect】
Since the high-accuracy stereolithography method by shape correction according to the present invention is configured as described above, complete three-dimensional shape correction can be performed, and precise processing becomes possible.
[0049]
Since the cross-section is calculated after the unit solid shape is corrected to the original solid figure input to the computer, and modeling is performed, the failure of processing due to lack of support is prevented by automatically diagnosing the necessary part of the support.
[0050]
In addition, the portion where the filling scan with the light beam is performed is not subjected to three-dimensional distortion due to the progress of post-curing by performing irradiation processing at a scanning speed faster than the contour scanning in a range where uncured resin does not remain inside.
[0051]
Modeling with precise thickness control based on surface data and solid data becomes possible.
[0052]
By changing the scanning speed, the size of the unit curing shape by the light beam is changed, and continuous control of the laser output is not required, so that the apparatus can be realized easily.
[0053]
The machining accuracy can be controlled by partially changing the stacking interval.
[0054]
By changing the irradiation direction of the light beam using a lens or a hologram, it is possible to improve the processing accuracy by creating and processing a hardened shape that smoothly fits the surface of the three-dimensional figure.
[0055]
By disposing the cylinder in the resin liquid layer and lowering the resin liquid with the piston so that the resin liquid does not overflow, it is possible to prevent the molded article from shaking and improve the processing accuracy.
[0056]
The resin discharged by the piston is moved to the upper part of the resin container outside the cylinder provided in the resin container, and this is discharged onto the resin fixing base and laminated, thereby eliminating the need for an auxiliary tank and making the processing device compact. Can be.
[0057]
Photo-curing resin with photo-reactivity has a large change in characteristics due to temperature, but when supplying resin partially taken out from the resin container due to piston pressure or the like, the light beam can be controlled by controlling the temperature of the resin to be supplied. Since the liquid surface can be kept at a constant temperature from the surface where the irradiation is performed, there is an energy saving effect, the apparatus becomes simple, temperature control can be performed quickly, and the life of the resin can be extended.
[0058]
Irradiation with a multi-wavelength light beam using a wavelength-dependent color former can selectively change the color of a cured product that partially or entirely creates.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of a three-dimensional modeling apparatus for performing a high-precision optical modeling method by shape correction according to the present invention.
FIG. 2 is a side view of FIG.
3 is a plan view of FIG. 1. FIG.
FIG. 4 is a schematic view showing scanning of a light beam when performing cylindrical shaping.
FIG. 5 is a schematic diagram showing a unit cured shape and a correction amount.
FIG. 6 is a perspective view showing a beam center position graphic when a rectangular parallelepiped shape is formed.
FIG. 7 is a schematic diagram for explaining a method of filling and scanning a thickness portion of a three-dimensional figure provided with a hollow portion.
FIG. 8 is a cross-sectional view of an essential part showing an apparatus for obtaining a unit cured shape that smoothly fits a three-dimensional figure.
FIG. 9 is a flowchart showing processing steps of a high-precision optical modeling method by shape correction according to the present invention.
FIGS. 10A, 10B, and 10C are schematic views showing a modeled object formed by intentionally leaving an uncured resin, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Resin container 2 Cylinder 3 Smooth plate 4 Resin adhering stand 5 Motor 6 Guide 7 Piston lift stand 8 Resin jet 9 Piston 10 Rubber packing 11 Resin pumping pump 12 Solid matter mixing prevention net 13 Lens 21 Cylinder 22 Beam center figure 23, 23 'Unit curing shape 24 Correction amount 25 Light beam 31 Original solid figure 32, 33 figure

Claims (2)

In the stereolithography method of manufacturing a resin model by irradiating a horizontal surface of a photocurable resin with a laser beam,
In order to correct the shape deformation due to the hardening spread of the resin,
Vertex of the original solid figure formed by a number of faces (or control point) coordinates to move (or newly added), to create a beam center position figure,
Stereolithography, wherein the resulting calculated cross section from the beam center position figure to stereolithography. The laser beam is irradiated at a speed faster than the contour scanning within a range in which the uncured resin does not remain when irradiating the laser beam. 1 Stereolithography described in 1.

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