JP3170832B2 - Optical molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical shaping method, and more particularly to an optical shaping method suitable for use in an optical shaping apparatus for forming a three-dimensional shape by irradiating a photocurable resin with a beam.

[0002]

2. Description of the Related Art FIG. 2 is a perspective view showing an example of an optical shaping apparatus 1 according to the prior art. The optical shaping apparatus 1 includes an elevator apparatus 10, a resin storage tank apparatus 30, and a beam generation apparatus 40, each of which has a general reference number, and further includes a control apparatus 70 electrically connected to these apparatuses. Has. The elevator device 10 includes an upper end portion 12 and a stage portion 1.
6 and a connecting portion 14 connecting the upper end portion 12 and the stage portion 16, and the stage portion 16 can be arranged in the resin 34.

The elevator apparatus 10 further includes an upper end 12
And a feed screw 20 screwed to the nut 18. The feed screw 20 is connected to a drive unit of a stepping motor 22. When the stepping motor 22 is actuated, the feed screw 20 rotates and generates an axial biasing force that drives the nut 18 upward or downward.

When the nut 18 moves up and down, the stage 16 moves up and down correspondingly. The stepping motor 22 may be operated so that the stage 16 moves stepwise at a predetermined pitch. An elevator position detector 78 for detecting the position of the stage 16 is arranged adjacent to the elevator device 10.

[0005] The resin storage device 30 has a storage container 32 in which a liquid photocurable resin such as an ultraviolet curable resin is stored. The stage unit 16 of the elevator device 10 is disposed in a storage container 32,
It is configured to be able to move up and down while immersed in resin.

The beam generator 40 includes a laser beam oscillator 42 and an acousto-optic modulator (A / O modulator) 44.
And the focus controller 46, and the acousto-optic modulator 4
A first total reflection mirror 52 and a second total reflection mirror 54 are disposed in front of and behind 4, respectively. The laser beam oscillator 42 may be configured to generate an exposure beam laser such as an argon ion laser having a wavelength of 360 nm or a helium cadmium laser having a wavelength of 325 nm.

The acousto-optic modulator 44 is configured to control the progress of the exposure beam, and has a switching function of permitting the passage of the exposure beam or blocking the passage of the exposure beam. The focus controller 46 may include a focusing lens 56 for narrowing the luminous flux of the exposure beam. With the focusing lens 56, the exposure beam forms a beam spot 62 having a predetermined diameter on the liquid surface 36 of the resin 34 stored in the storage container 32. Squeezed to provide.

A first galvano scanner 48 and a second galvano scanner 50 are arranged adjacent to the resin storage device 30. The first galvano scanner 48 includes a first galvanometer mirror 48a and the galvanometer mirror 48a. And a drive unit 48c for rotating the galvanomirror 48a around the rotation axis 48b.
Similarly, the second galvano scanner 50 includes a second galvanometer mirror 50a, a rotation shaft 50b, and a driving unit 50c.

[0009] Beam oscillator 42, first total reflection mirror 5
2, acousto-optic modulator 44, second total reflection mirror 54,
Focus controller 46 and focusing lens 56
Is the exposure beam 6 generated by the beam oscillator 42
0 is reflected by the first total reflection mirror 52 and reaches the second total reflection mirror 54 via the acousto-optic modulator 44,
The second galvano mirror 50 a is reflected by the second total reflection mirror 54 and passes through the focusing lens 56.
Are aligned so that they reach

The first galvanomirror 48a and the second galvanomirror 50a are arranged such that the exposure beam 60 reflected by the second galvanomirror 50a is reflected by the first galvanomirror 48a, and changes its direction so that the liquid level of the resin is reduced. 36 and is arranged to form a beam spot 62 thereon.

The first galvanomirror 48a has a rotating shaft 48
When rotated about b, the angle of incidence on the reflecting surface 48d changes, and the path of the exposure beam 60 reflected on the reflecting surface 48d changes. Similarly, when the second galvanometer mirror 50a is rotated around the rotation axis 50b, the incident angle with respect to the reflection surface 50d changes, and the path of the exposure beam 60 reflected by the reflection surface 50d changes. Thus galvanometer mirror 48
When a and 50a are respectively rotated around their rotation axes 48b and 50b, the path of the exposure beam changes, and the beam spot 62 moves two-dimensionally on the liquid surface 36 of the resin.

Here, on the resin surface 36, a direction approaching or remote from the elevator apparatus 10 is called a first scanning direction, and a direction parallel to the connecting portion 14 of the elevator apparatus 10, that is, a first scanning direction. The direction perpendicular to the scanning direction is called a second scanning direction.

The arrangement of the galvanomirrors 48a and 50a is as follows.
Preferably, the first galvanomirror 48a is
When rotated about b, the path of the exposure beam 60 reflected by the reflection surface 48d changes on a plane perpendicular to the rotation axis 48b, whereby the beam spot 62 moves along the first scanning direction. When the second galvanomirror 50a is rotated about the rotation axis 50b, the path of the exposure beam 60 reflected by the reflection surface 50d changes on a plane perpendicular to the rotation axis 50b, whereby the beam spot 62 is It is selected to move along two scanning directions.

The control device 70 includes an A / O modulator controller 72 for controlling the switching operation of the acousto-optic modulator 44 and an elevator control for controlling the operation of the stepping motor 22 based on the position signal from the elevator position detector 78. And a galvo controller 74 for controlling the A / O modulator controller 72, the focus controller 46, the first galvano scanner 48, the second galvano scanner 50, and the elevator controller 76.

FIG. 3 shows the optical shaping apparatus 1 shown in FIG.
FIG. The stage section 16 of the elevator apparatus 10 is arranged in parallel with the liquid surface 36 of the resin, and can move downward in the liquid resin when the stepping motor 22 is operated. When the stepping motor 22 is operated by a signal from the elevator controller 76, the stage 16 is moved downward step by step at a predetermined pitch. When a three-dimensional object is formed by the optical shaping apparatus 1, first, the stage 16 of the elevator apparatus 10 is used.
Is located at the start position indicated by the solid line in FIG.

In this starting position, the upper surface of the stage section 16 is located one pitch below the liquid surface 36 of the resin, and therefore, a liquid layer of the resin having a depth of one pitch exists on the upper surface. Becomes When the exposure beam 60 is irradiated on the liquid surface 36 of the resin, the resin is cured at a predetermined depth to a portion corresponding to the beam spot 62 on the liquid surface 36.

The downward movement pitch of the stage 16 is as follows:
The size is set to almost half the curing depth by the exposure beam. For example, when the curing depth of the resin is 0.5 to 0.7 m
m, the moving pitch of the stage section 16 is 0.2 to 0.1.
It may be set to 3 mm. With the stage section 16 at the start position, the exposure beam 60 is placed on the stage section 16.
Is scanned, a cured strip of resin is formed along the locus of the beam spot 62. A large number of cured strips assemble to form a cured resin layer.

When a cured resin layer is formed on the stage 16, the stage 16 is moved downward by one pitch. When the stage section 16 is moved downward by one pitch, the cured layer formed thereon is also moved downward together with the stage section 16 and the resin flowing from the surroundings onto the cured layer has a resin pitch of one pitch. A liquid layer is formed.

An exposure beam is again irradiated on the liquid surface of the resin on the stage section 16 to form a cured resin layer in a laminated state. In this way, the three-dimensional object 80 having a predetermined shape is formed by laminating many cured layers. The shape of each cured layer of the resin corresponds to each of the cross-sectional shapes at one pitch of the three-dimensional object 80.

The photo-curing resin 34 easily adheres the newly formed cured strip to the adjacent cured strip that has already been formed, and the newly formed cured layer easily contacts the adjacent cured layer that has already been formed. When the stage 16 is moved one pitch downward, the resin flows more easily from the surroundings and a resin liquid layer having a depth of one pitch is formed on the hardened layer when the stage 16 is moved one pitch downward. It is desirable to have a sufficiently low viscosity so as to be, for example, a UV-curable modified acrylate.

FIG. 4 is a block diagram of a control device 70 used in the optical shaping device 1 according to the prior art shown in FIG. The control device 70 includes the storage device 102 and the modulation circuit 1
04 and a beam irradiation position control circuit 100 including the same.
The storage device 102 is a so-called CA via an input terminal 120.
It is connected to a three-dimensional shape programming device such as D, and is configured to store pixel signals decomposed in the X direction and the Y direction of the three-dimensional shape designed by the programming device. The modulation circuit 104
It is configured to convert a pixel signal from the storage device 102 into a coordinate signal indicating a position in a scanning region on the liquid surface of the resin.

The control device 70 includes a scan mode switching circuit 1
10, whereby the scanning method of the exposure beam is switched to one of the raster scanning method and the vector scanning method. In the case of the raster scanning method, the first raster scanning method and the second scanning method are used. The mode is switched to one of the raster scan modes.

The raster scan method uses a beam spot 6
The first raster scan method has a main scan direction in the first scan direction or the X direction, and the second raster scan method has a main scan direction in the X direction. It has a main scanning direction in the second scanning direction or the Y direction. The vector scan method is configured such that the scanning direction changes every time without having a constant main scanning direction.

Of the coordinate signals sent from the modulation circuit 104, the signal in the first scanning direction or the X direction is the first D / A
The signal is converted into an analog signal by the converter 106a, and is transmitted from the output terminal 122 to the drive unit 48c of the first galvano scanner 48 via the first gate circuit 108a.
Among the coordinate signals sent from the modulation circuit 104, the signal in the second scanning direction or the Y direction is the second D / A converter 106
b to the second gate circuit 1
The signal is transmitted from the output terminal 124 to the drive unit 50c of the second galvano scanner 50 via 08b.

The coordinate signal generated by the modulation circuit 104 is sent to the focus control circuit 112 and sent to the focus controller 46 via the output terminal 126, whereby the focus of the focusing lens 56 is controlled and the liquid level of the resin is adjusted. A beam spot 62 having a predetermined diameter is obtained above.

A stepping motor drive circuit 114 and an A / O modulator drive circuit 116 are connected to the beam irradiation position control circuit 100. The signal from the stepping motor drive circuit 114 is sent to the stepping motor 22 via the output terminal 128.

The operation of the stepping motor 22 is such that the stage 16 of the elevator apparatus 10 is arranged at the starting position at the start of work, and when a cured resin layer is formed by irradiation with a beam, the stage 16 is moved downward by one pitch. It is controlled to be moved. The signal from the A / O modulator driving circuit 116 is sent to the A / O modulator 44 via the output terminal 130, and thereby the exposure beam 6
Zero progression is allowed or blocked.

[0028]

FIG. 5 shows a process of manufacturing a three-dimensional object by an optical shaping method according to the prior art. On the stage section 16 of the elevator apparatus 10, a plurality of resin cured strips 144 and 142 formed by scanning an exposure beam by a raster scan method.
Is arranged. The hardened stripes are formed by scanning the beam spot 62 on the liquid surface along the first scanning direction, and the hardened stripes are gathered to form a hardened layer 140 having a hole 142.

The scanning of the beam spot 62 is performed by the hardened layer 140.
Scans the next beam spot 62 adjacent to the first hardening strip formed thereby. In this manner, cured strips adjacent in the second scanning direction are formed one after another. Before or after forming the hardened layer by the beam spot scanning by the raster scan method, though not shown, an outline around the hardened layer is formed by the beam spot scan by the vector scan method.

When the cured layer is formed, the elevator device 1
The stage section 16 of 0 is moved one pitch downward, the resin flows from the periphery onto the hardened layer, and a resin liquid layer having a depth corresponding to one pitch is generated on the hardened layer. The beam spot 62 is scanned on the liquid surface of the resin, and a new cured layer is formed on the already formed cured layer. In this case, the main scanning direction of the beam spot 62 may be the same as or different from the main scanning direction of the beam spot 62 in the case of an already formed cured layer.

The resin is agglomerated by the irradiation of the exposure beam 60, but generates heat at the same time. Since the newly formed hardened layer has a higher temperature than the existing layer,
It shrinks more than the existing layer and the shape is distorted. Therefore, manufacturing a three-dimensional object with high accuracy is prevented.

In view of the above, an object of the present invention is to make it possible to manufacture a three-dimensional object with high accuracy.

[0033]

According to the present invention, a liquid photo-curable resin is irradiated with a beam 60 to form a cured layer 2 of a resin having a shape corresponding to a predetermined three-dimensional cross section. A cured resin layer 2 is further formed on the cured resin layer 2, and the cured resin layer 2 is sequentially formed to form a three-dimensional object. In the process of forming the cured layer 2 of the resin having the shape as described above, the vicinity of the contour portions 6a and 6b is irradiated with the beam 60 at high density to increase the rigidity of the generating portion, and the inside 7a performs sparse scanning to reduce the contraction force. Good beam 6
In this case, the 0 route is selected. Further, in the optical shaping method according to the present invention, in the scanning path, the contour portion includes a path along the outer periphery of a shape corresponding to the cross section of the three-dimensional shape.

[0034]

According to the present invention, as shown in FIG.
Since each hardened layer 2 has a higher rigidity in the high-density portions of the beam 60 of the cross-sectional contours 6a and 6b than when the hardened layer 2 is formed with a uniform irradiation density of the beam 60, the rigidity of the generated workpiece is efficiently increased. Can be enhanced. On the other hand, the contraction force is
The area ratio is determined by the area ratio between the high-density portion 6b and the low-density portion in the interior 7a. Since the distortion is smaller as the contraction force of the created layer is smaller than that of the existing generation unit, the distortion can be reduced by the present invention.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An optical molding method according to the present invention will be described below with reference to FIG. FIG. 1 shows a process of manufacturing a three-dimensional object by the optical shaping method according to the present invention. The optical shaping method according to the present invention is implemented using the same optical shaping apparatus 1 according to the prior art shown in FIGS. 2 to 4 as shown in FIG.

Also in this embodiment, a cured resin layer 2 having holes 4 is formed on the stage 16 of the elevator apparatus 10. The cured layer 2 of the resin according to this embodiment scans the beam 60 at a high density in the outer peripheral portion 6a and the inner peripheral portion 6b to form a dense cured strip 6. In the interior 7a, the beam 60 is scanned at a low density so as to form a sparse hardened strip 7.

The dense hardened strip 6 of resin preferably has an outer peripheral strip having a start 8 around it and extending along the contour of a shape corresponding to the cross section of the completed three-dimensional article. An inner circumferential strip connected to the outer circumferential strip at an adjacent position and extending inside and adjacent to the outer circumferential strip. The generation of the inner circumferential strip is continued until the width of the outer circumferential portion 6a reaches a predetermined dimension 6C.

The sparse hardened strips 7 of the resin are drawn in a relatively sparse pattern on the surface surrounded by the dense hardened strips 6. Others are the same as the conventional one.

The scanning path of the beam spot 62 is preferably configured as a continuous path, but may be configured as a discontinuous path when the cross section has a complicated shape.

The optical shaping method according to the present embodiment is performed using the raster scan method for the inside 7a, but may be performed using the vector scan method or a combination of the vector scan method and the raster scan method.

The scanning path of the beam spot 62 is selected according to the shape of each section of the three-dimensional object 80, and the selection is made by a programming device connected to the storage device 102 and stored in the storage device 102.

According to the present embodiment, as shown in FIG. 1, since the outside of the cross section has higher rigidity than when formed at a uniform density, the rigidity of the work after generation can be efficiently increased. . On the other hand, the contraction force is determined by the area ratio between the high-density portion and the low-density portion. In this case, since the low-density portion is wider, the contraction force can be reduced. Since the distortion is smaller as the contraction force of the created layer is smaller than that of the existing generator, according to the present embodiment, the distortion can be reduced. While the embodiments of the present invention have been described above, it will be understood that various changes and modifications can be made without departing from the spirit of the present invention.

[0043]

According to the present invention, since the rigidity of the product can be increased in spite of the heat shrinkage force, there is an advantage that a three-dimensional article with high precision is manufactured.

[Brief description of the drawings]

FIG. 1 is a view showing a cured strip of a resin formed by an optical shaping method according to the present invention.

FIG. 2 is a perspective view of an optical shaping apparatus according to the related art.

FIG. 3 is a partially detailed view of the optical shaping apparatus shown in FIG. 2;

FIG. 4 is a block diagram of a control device of the optical shaping device shown in FIG.

FIG. 5 is a view showing a cured strip of a resin formed by an optical shaping method according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical shaping apparatus 2 Hardened layer 4 Hole 6 Dense hardened strip 6a Outer part 6b Inner circumferential part 7 Sparse hardened strip 7a Inside 60 Exposure beam 8 Start part

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 67/00

Claims (2)

(57) [Claims] 1. A liquid photocurable resin is irradiated with a beam to form a cured resin layer having a shape corresponding to a predetermined three-dimensional cross section, and further irradiated with a beam to further cure the resin on the cured resin layer. An optical shaping method for forming a layer and forming a three-dimensional object by sequentially forming a cured layer of resin in this way, wherein in the process of forming each cured layer of resin having a shape corresponding to the cross section of the three-dimensional shape, An optical shaping method characterized by irradiating a beam at a high density near a contour portion to increase the rigidity of a generating portion, and performing sparse scanning inside to irradiate a beam so as to reduce a contraction force. 2. The optical shaping method according to claim 1, wherein in the beam scanning path, the outline includes a path along an outer periphery of a shape corresponding to a cross section of the three-dimensional shape. Modeling method.